Dissipative Behavior of Some Fully Non-Linear

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corrupt representation

Corrupt RepresentationIntroductionCorrupt representation refers to the act of individuals in positions of power or authority engaging in unethical practices, such as bribery, fraud, or embezzlement, to serve their personal interests instead of fulfilling their responsibilities to the public. This phenomenon is prevalent in many countries and has serious consequences for society, including undermining trust in institutions, distorting democratic processes, and hindering economic development. In this article, we will delve into the causes, effects, and potential solutions to corrupt representation.Causes of Corrupt Representationck of transparency and accountability: When there is a lack oftransparency in government and public institutions, it becomeseasier for corrupt practices to thrive. Insufficientaccountability mechanisms allow individuals to engage in corruptactivities without fear of being caught or facing consequences. 2.Weak legal frameworks: Inadequate laws and regulations pertainingto corruption provide loopholes for individuals to exploit. Whenlaws are not stringent or enforced effectively, it becomes easier for corrupt practices to go unpunished.3.Low salaries and inadequate resources: In some cases, individualsin positions of power may resort to corruption due to low salaries or inadequate resources. When public servants struggle to makeends meet or lack the necessary tools to perform their dutieseffectively, they may be more susceptible to engaging in corruptpractices.4.Cultural and societal factors: Cultural norms and societalexpectations can influence the prevalence of corruptrepresentation. In societies where corruption is more accepted or even seen as a necessary means to get ahead, individuals may bemore inclined to engage in corrupt practices.ck of education and awareness: Limited access to education andlack of awareness about the negative consequences of corruptioncan contribute to its perpetuation. When individuals are noteducated about the detrimental effects of corruption, they may not fully understand the importance of ethical behavior in positionsof power.Effects of Corrupt Representation1.Undermining trust in institutions: Corrupt representation erodespublic trust in government and public institutions. Whenindividuals in positions of power are perceived as corrupt,citizens lose faith in the ability of these institutions to serve their interests and uphold the rule of law.2.Distorting democratic processes: Corruption in representation candistort democratic processes by influencing elections,manipulating public opinion, and impeding the fair and equalrepresentation of citizens’ interests. This undermines theprinciples of democracy and erodes the legitimacy of electedofficials.3.Hindering economic development: Corruption diverts public fundsaway from essential services and infrastructure projects,hindering economic development. When resources that should beallocated for public welfare are siphoned off through corruptpractices, it leads to a lack of investment in critical sectors,perpetuating poverty and inequality.4.Encouraging a culture of corruption: Corrupt representation canperpetuate a culture of corruption, where unethical behaviorbecomes normalized and expected. This makes it increasinglydifficult to break the cycle of corruption and establish a culture of integrity and transparency.Solutions to Corrupt Representation1.Strengthening legal frameworks: Governments should enact andenforce comprehensive anti-corruption laws that address thevarious forms of corrupt representation. These laws should include provisions for the investigation, prosecution, and punishment ofcorrupt individuals, as well as protection for whistleblowers.2.Enhancing transparency and accountability: Governments and publicinstitutions should prioritize transparency and accountability in their operations. This can be achieved through measures such asthe disclosure of financial information, the establishment ofindependent oversight bodies, and the implementation of effective monitoring mechanisms.3.Promoting education and awareness: Investing in education andraising awareness about the consequences of corruption are crucial in combating corrupt representation. By promoting ethical valuesand integrity from an early age, societies can foster a culturethat rejects corruption and values honesty and accountability.4.Strengthening international cooperation: Corruption is a globalissue that requires international cooperation. Governments should collaborate with international organizations and other countriesto share best practices, exchange information, and coordinateefforts in combating corrupt representation.5.Encouraging citizen participation: Engaging citizens in decision-making processes and encouraging their active participation canhelp prevent corrupt representation. By promoting transparency,citizen oversight, and public engagement, governments can ensurethat the interests of the public are represented and thatcorruption is less likely to occur.ConclusionCorrupt representation poses significant challenges to societies around the world. By understanding the causes and effects of corruption, as well as implementing effective solutions, governments and citizens can work together to combat this pervasive issue. Strengthening legal frameworks, promoting transparency and accountability, investing in education, fostering international cooperation, and encouraging citizen participation are all crucial steps in creating a society that values integrity and rejects corrupt representation.。

Guidelines for ALE Modeling in LS-DYNA

DRAFT July 2009Guidelines for ALE Modeling in LS-DYNAJim Day, LSTCReviewersIan Do, LSTC;Jerry Farstad, BoeingIn modeling fluid or fluid-like behavior, a Lagrangian approach, wherein the deformation of the finite element mesh exactly follows the deformation of the material, is often not suitable owing to the very large deformation of the material. Mesh distortion can become severe, leading to a progressively smaller explicit time step and eventual instability.In contrast, an Eulerian or ALE (Arbitrary Lagrangian Eulerian) solution method, wherein the materials flow (or advect) through the Eulerian/ALE mesh which itself is either fixed in space (Eulerian) or else moving according to some user-issued directives (ALE), is much better suited to modeling of fluid or fluid-like behavior.In LS-DYNA, Lagrangian and Eulerian/ALE solution methods can be combined in the same model and the fluid-structure interaction (FSI) may be handled by a coupling algorithm. Thus parts that deform a moderate amount, such as structural components of metals, composites, or polymers, can be modeled with Lagrangian elements whereas fluids, such as air and water, and fluid-like parts, such as birds or ice impacting at high velocity, can be modeled withEulerian/ALE elements. Bear in mind that at very high pressure, temperature, and/or strain rate, even structural materials (metal, concrete, soil, etc.) may behave in a fluid-like manner and thus may be more suitably modeled with Eulerian/ALE elements in such cases.This article gives an introduction to and general guidelines for modeling with Eulerian/ALE elements. Modeling of airbags is a special and complex subtopic that is not addressed in this document.Introduction – Lagrangian vs. Eulerian vs. ALE FormulationsThe figure below shows a 3-frame sequence of a water projectile striking a metal plate. Each row in this figure represents a different modeling approach and helps to illustrate the fundamental differences in Lagrangian (1st row), Eulerian (2nd row), and ALE formulations (3rd row). The solid blue portion represents the water projectile. The red outline is for reference only and marks the initial, undeformed location of the parts. The LS-DYNA input deck for the model that produced this figure is available at/anonymous/outgoing/jday/aero/3in1_impacting_plate.k.LAGRANGIANIn an all-Lagrangian approach (3-frame sequence shown in the top row), the nodes move directly along with the material and thus elements and materials translate, rotate, and deform together. Material does not cross element boundaries and thus the mass of material within each Lagrangian element never changes.EULERIANIn the sequence shown in the middle row of the figure, the metal target plate is Lagrangian, however the mesh of the water and surrounding void is Eulerian and thus their mesh remains fixed in space. The water (shown in solid blue) can move and deform within the fixed mesh. As the simulation progresses, the materials (water and void) cross element boundaries, i.e., with each time step some small amount of each material may flow or advect out of one cell (or element) and into an adjacent cell. At any given point in time, each Eulerian element may contain a mixture of water and void, hence the term “multi-material” is used in describing the element formulation. The process by which history variables, e.g., stresses, are calculated within a mixed element is beyond the scope of this modeling document.ALEThe third approach, shown in the bottom row of the figure, employs an ALE formulation in modeling the water projectile and surrounding void. Again, the metal target is Lagrangian. Unlike the Eulerian case in which the water and void mesh remain fixed, the ALE mesh is directed to move in some prescribed manner as the solution progresses. Thus Eulerian is a special case of ALE wherein the prescribed reference mesh velocity is zero. Subsequently we may refer to this general Eulerian/ALE class of methods as simply “ALE”. Unlike the wholly Lagrangian case in which the mesh and material move exactly together, the ALE mesh and the material do not move exactly together. Thus material advection across element boundaries isstill required but the amount of material advected each time step is generally less as compared to the Eulerian approach since the mesh is also moving. Generally the less material that is advected per time step, the more accurate the simulation. An additional advantage of ALE is that because the mesh can be directed to approximately follow along with the fluid material(s), generally fewer elements are needed as compared to the Eulerian approach. In other words, the entire spatial domain covered over the course of the simulation need not be meshed at the outset. MESH SMOOTHINGThere is a subclass of ALE modeling referred to as mesh smoothing in which the mesh conforms to the exterior boundary of the ALE material and the elements are reshaped using any of several smoothing algorithms. After the elements are smoothed, material advection occurs. Although this smoothing approach is available in LS-DYNA, it is less general and less robust than the case in which the ALE mesh need not conform to the material boundaries. Thus the ALE smoothing approach in LS-DYNA is not discussed any further in these modeling guidelines. Instead, when ALE is discussed, focus will be on the general ALE approach.FSIWhen Euler or ALE parts are required to interact with Lagrangian parts, some form of coupling (or fluid-structure interaction, FSI) feature must be defined. (The exception is if nodes are shared between the ALE mesh and the Lagrangian mesh at their juncture – a practice which is generally not recommended.) ALE-to-Lagrange coupling can be constraint-based but is more commonly penalty-based. The coupling commands in LS-DYNA are discussed in detail later in this article.LIMITATIONSThere are some limitations to the ALE approach to consider.The ALE solver in LS-DYNA is predominantly applicable to laminar flow. Also, the ALE solver is not a full Navier-Stokes solver and thus does not account for fluid boundary layer effects such as drag. Effects of fluid viscosity derive solely via the material model, e.g., via MU in *mat_null. The ALE solver (ALE compressible flow solver) has been developed with the intent of simulating short duration problems with high pressure and velocity gradients. The solver is not well suited to problems driven by low pressure gradients such as in acoustic problems nor is it suited to long duration problems (on the order of seconds or longer). The limitation in time duration is a result of the explicit time integration wherein the time step is limited based on element size and material soundspeed. In the case of ALE, time step may be further limited by the penalty stiffness of the ALE-Lagrange coupling.ALE is relatively expensive as compared to Lagrangian owing to the additional advection, interface reconstruction, and coupling computations.Advection associated with the ALE solver is inherently dissipative to some extent, e.g., pressure amplitude eminating from detonation of explosive tends to be underpredicted, especially when first order accurate advection is employed (METH = 1 in *control_ale). Nonphysical energy dissipation is generally reduced when second order accurate advection is employed (METH = 2)but there is some additional computational cost. Refining the mesh will also help to reduce energy loss but again there is additional computational cost.Results from the ALE solver may exhibit some slight to moderate mesh biasing effects. For example, a pressure wave originating from a point source in a fluid may become less and less spherical as the distance from the point source increases. This mesh biasing effect is reduced or eliminated when the mesh lines are parallel and perpendicular to the direction of wave propogation.ALE Element FormulationWhen two or more fluids or fluid-like materials (empty space counts as one material) are to be modeled using the ALE approach in LS-DYNA, the recommended element formulation for those materials is the multi-material ALE formulation (ELFORM = 11 in *section_solid). Although there are other ALE element formulations (ELFORM 5, 6, and 12), those are of interest perhaps only in an academic sense and will not be discussed here.To review, as the ALE materials flow through the ALE mesh, the material boundaries or interfaces in general do not coincide with the mesh lines. These material interfaces are internally reconstructed each time step based on the volume fractions of the materials within the elements. Each material which the user wants to track individually must be assigned a unique ALE multi-material group (AMMG) ID via the command *ale_multi-material_group. Parts sharing the same material properties may be included in the same AMMG ID or, at the user’s discretion, can be distributed into separate AMMG IDs to allow for independent tracking of each group. Materials which do not share the same material properties cannot be part of the same AMMG. Generally some portion of the ALE mesh is initially devoid of material or else is initially filled with a gas at STP condition (standard temperature and pressure). This void or pseudo-void provides space into which other, higher density materials may be transported as the simulation progresses. In our earlier example, water moved with time into elements initially devoid of material. Space initially devoid of material (and thus having zero mass, zero pressure, etc.) is modeled with *mat_vacuum. If the space is occupied by air or some other ideal gas with nonzero density, with or without nonzero pressure, a material model and an equation-of-state appropriate for such a gas, e.g., *mat_null and *eos_ideal_gas, should be assigned to that space. Motion of the ALE mesh is controlled by the family of command(s)*ale_reference_system_option. Without such a command, the ALE mesh will remain stationary thus becoming the special case of Eulerian. Using these commands, one can prescribe the motion of the ALE mesh in a very specific and/or predetermined manner, or the mesh motion can be made to approximately follow the mass-weighted average velocity of the ALE materials. The latter option is perhaps the most common and useful choice and is invoked by setting PRTYPE=4 in *ale_reference_system_group.Since the ALE method allows for materials to flow between elements and the user has direct control over the ALE mesh motion, ALE element distortion is generally of no concern. Itfollows that hourglass deformation is less of an issue in the case of ALE than in the case of Lagrangian, and the need for hourglass forces to restrict hourglass deformation is much reduced or eliminated. For materials modeled as ALE, hourglass formulation 1 and a much reduced hourglass coefficient, e.g., 1.0E-6 or less, are recommended to prevent application of inappropriate hourglass forces. This recommendation is especially true in the case of modeling gases and liquids. Starting in version 971 R3.1, the default hourglass coefficient for all parts with ELFORM=11 is set to 1.E-06. The default hourglass control can always be overridden by the user using *hourglass and HGID in *part. Such an override may be appropriate in the case of solid (non-fluid) ALE materials.MeshingHexahedral elements with reasonable aspect ratios should be used for the initial ALE mesh. Degenerate element shapes such as tetrahedrons and pentahedrons should be avoided as they may lead to reduced accuracy at best and perhaps numerical instability during the advection. Bear in mind that use of *ale_reference_system may affect the element shapes as the solution progresses. If element shapes become unreasonable, controls in the*ale_reference_system_option command(s) may need to be adjusted to maintain reasonable element shapes.An initial ALE mesh may be constructed using one of the following two approaches:•The initial mesh of the ALE domain may be constructed to conform to the materials, i.e., there are no mixed (or partially filled) cells in the initial configuration. Mesh lines follow the outer contour of each AMMG.• A regular, orthogonal mesh of the ALE domain may constructed with no restriction that mesh lines follow the outer contour of each AMMG. In this case, there will likely beelements containing more than one AMMG. For these mixed elements, the initialvolume fractions of AMMGs must be prescribed via*initial_volume_fraction(_geometry). This command has a "geometry" option thatautomates the assignment of initial volume fractions to ALE elements. At the conclusion of the automatic assignment of initial volume fractions, LS-DYNA writes a filecontaining the *initial_volume_fraction data for each ALE element before continuingwith the simulation. This file can be utilized in subsequent runs in lieu of the*initial_volume_fraction_geometry command, thereby speeding up initialization.What constitutes an appropriate degree of refinement for the ALE mesh is at least partially dictated by the geometric characteristics of the Lagrangian parts. Though not a requirement, a reasonable goal is to have the ALE elements be nearly the same size as the Lagrangian elements where coupling is to take place.If ALE material is to flow through any passages in the Lagrangian mesh, use at least 5 to 10 elements across the passage width in order to adequately resolve the flow. Consider as aguideline using a number of elements across the passage equal to the points necessary to resolve a parabolic shape such that the area of the parabola is preserved to the user’s required accuracy.As stated under the limitations section above, results may exhibit some mesh bias. If these effects appears to be significant, reconstruction of the initial mesh and controls on mesh movement (*ale_reference_system_option) may be warranted.Coupling Lagrangian Surfaces to ALE MaterialsMost often, in Fluid-Structure Interaction (FSI) problems modeled with LS-DYNA, the fluids (and sometimes other materials that behave in a fluid-like manner) are modeled with ALE hexahedrons and the structure is modeled with Lagrangian shells or solids. In such a model, the Lagrangian mesh usually does not share nodes with the ALE mesh. Rather, the two meshes interact via a coupling algorithm defined with the command *constrained_lagrange_in_solid. This coupling serves to generate forces that resist penetration of the ALE material through the Lagrangian parts. Coupling is a key and sometimes complex aspect of ALE modeling. Some recommendations for using *constrained_lagrange_in_solid for coupling are provided below. Let us consider some of the more critical parameters of the *constrained_lagrange_in_solid card. $-------------------------------------------------------------------------------*CONSTRAINED_LAGRANGE_IN_SOLID$ slave master sstyp mstyp nquad ctype direc mcoup1 200 1 02 4 2 -1$ start end pfac fric frcmin norm normtyp DAMPFRAC0.0 0.0 0.100000 0.0 0.300000$ cq hmin hmax ileak pleak lcidpor0.0 0.0 0.0 0 0.10000$4A IBOXID IPENCHK INTFORC IALESOFT LAGMUL PFACMM THKF0 0 1 0 0 0 0.0$-------------------------------------------------------------------------------The slave side parameters SLAVE and SSTYP identify the Lagrangian part(s) or segment sets to be considered in the coupling. The master side parameters MASTER and MSTYP identify, by part or part set ID, the ALE mesh that will interact with the slave side. Again, the master side identifies mesh but not material. Together, SLAVE, SSTYP, MASTER, MSTYP define the overlapping computation domains (Lagrangian and ALE) that the code will search for interaction. This does not yet specify which ALE material(s) flowing through the ALE domain are to be coupled to the Lagrangian structure.A separate parameter MCOUP identifies the specific ALE materials, or more precisely, the AMMGs that will interact with the slave side.To summarize coupling thus far, for coupling forces to be developed on a Lagrangian surface, that surface must (1) reside on the slave side of a *constrained_lagrange_in_solid, (2) that surface must be spatially overlapping a portion of the ALE mesh identified by the master side, and (3) that surface must be penetrating at least one of the AMMGs identified by the parameter MCOUP. See below for more discussion of MCOUP.The parameter NQUAD determines the number of coupling points distributed over each Lagrangian slave segment. If NQUAD=2 (default), then there are 2x2 = 4 coupling points on each Lagrangian slave segment. The coupling algorithm looks for penetration of any ALE material meeting the conditions of MASTER, MSTYP, and MCOUP across each of the coupling points. If penetration at a coupling point is found, coupling forces are applied to counteract penetration. The larger the value of NQUAD, the more expensive the coupling and the more likely the coupling forces will be excessive. If the Lagrangian slave segments are approximately the same size as or smaller than the Eulerian/ALE element faces, NQUAD=2 will generally suffice. If the Lagrangian slave segments are coarser/larger than the ALE element faces, NQUAD may need to be raised to 3 or higher to provide proper coupling.The parameter CTYPE identifies the coupling algorithm employed. In most applications, penalty-based coupling is more robust and is therefore preferred over constraint-based coupling. Thus CTYPE should generally be set to 4, or in the case where the Lagrangian slave side is comprised of solids which may be eroded due to material failure criteria, CTYPE should be set to 5. There are other CTYPEs that allow for physical porosity of the Lagrangian surfaces, e.g., as in the case of an airbag or parachute, but a discussion of modeling porosity effects is outside the scope of this document. For the special case of coupling Lagrangian beam elements within a Lagrangian solid mesh, e.g., as used in coupling rebar to concrete, the constraint-based coupling algorithm should be used (CTYPE=2).The parameter DIREC should generally be set to 2 as this most often best represents the physical nature of the interaction. Furthermore, it is also the most reliable and robust option. With DIREC=2, normal direction coupling occurs only in compression. Tangential coupling, associated with friction between materials, is controlled separately via the parameter FRIC.The parameter MCOUP defines the AMMG(s) to which the Lagrangian slave side is coupled. In cases where one AMMG dominates the forces imparted to the Lagrangian structure and the forces from any other AMMGs can be neglected, MCOUP should be set to 1. This might be thecase where the density of one AMMG is far greater than the density of the other AMMGs. In cases where the effects of two or more AMMGs need to be considered in the coupling, MCOUP can be set to a negative number. In this case, |MCOUP| identifies a set of one or more AMMGs to be considered in the coupling. That set is defined using the command *set_multi-material_group_list.When the slave side of the coupling is comprised of Lagrangian shells or of a segment set comprised of Lagrangian element faces, an additional requirement of successful coupling is that the slave shell/segment normals must point toward the AMMGs to which coupling is desired. If the slave side normals happen to point away from the AMMGs, these normals can be automatically reversed and the situation remedied by setting the parameter NORM=1. Note that setting NORM to 1 reverses all the normals of the Lagrangian slave segments. Thus it is imperative that the slave segment normals are at least consistently oriented either pointing toward (NORM=0) or away from (NORM=1) the ALE material.Leakage is an undesireable condition whereby coupling does not prevent unreasonable penetration of ALE material through Lagrangian surfaces. Problems of leakage can be identified visually when postprocessing as described in a later section. A small amount of leakage is to be expected for penalty-based coupling and can be tolerated, just as in the case of small penetrations seen for penalty-based contact. The following modifications to the coupling input are presented as possible remedies to excessive leakage.•Increase the value of NQUAD if it is suspected that there are too few coupling points on the Lagrangian segments. Be judicious here because increasing NQUAD drives up thecpu time.•When coupling to a shell surface, assign one AMMG ID to the ALE material on one side of the shell surface and a different AMMG ID to the ALE material on the opposite side.Of course, this practice is a requirement if there are two physically different materials to either side. The point is that this guideline applies even when the same physical fluidexists on both sides of the shell surface.•Use a separate *constrained_lagrange_in_solid command for each AMMG. This will require the use of a negative MCOUP value and a *set_multi-material_group_listcommand for each *constrained_lagrange_in_solid command.•An appropriate coupling stiffness is key to good coupling behavior when CTYPE=4 or 5.In most cases, the default penalty stiffness (PFAC=0.1) works fine and this should beyour starting point. If it becomes clear that the default coupling stiffness is inadequate,simply increasing PFAC (by 5 or 10 times) might resolve the problem. A more logicalapproach is to set PFAC to a negative integer which tells LS-DYNA that the couplingstiffness comes from curve |PFAC| wherein the abscissa is penetration distance and theordinate is coupling pressure. *Define_curve should be used to define curve |PFAC|.(Let’s say PFAC=-20. Then curve 20 defines coupling pressure vs. penetration distance.)A rule-of-thumb in defining the curve is to define two points: (0,0) and (1/10th the ALEelement dimension, maximum pressure observed in the ALE mesh near the leakage site).Be aware that an increase in coupling stiffness may result in a smaller time step size. Just as far too small a coupling stiffness has detrimental effects, so does far too great acoupling stiffness.•For coupling of ALE gases to Lagrangian parts (low-density-to-high-density materials), it may help to set the parameters ILEAK=2 and PFACMM=3.As a final word in modeling coupling between ALE and Lagrangian parts, there is a coupling method that may serve as a preferred alternative to constrained_lagrange_in_solid in some cases. *Ale_fsi_projection uses a constraint-based approach, projecting the nearest ALE nodes onto the Lagrangian surface. Coupling can be in all directions, in tension and compression only, or in compression only. Energy is not conserved in this approach but it has been shown to be effective in coupling fluid to tank walls in a sloshing tank simulation. An example in which only gravity is applied to develop hydrostatic pressure in a tank of water is provided in/anonymous/outgoing/jday/aero/init_water_coupled_to_tank_fsi_projection.k . The figure below shows the hydrostatic state at the end of the simulation.In the next two examples, the container moves horizontally to introduce sloshing of the water. /anonymous/outgoing/jday/aero/init_water_coupled_to_tank_fsi_projection_wi th_sloshing_2couplings.k uses *ale_fsi_projection to couple the water to the tank./anonymous/outgoing/jday/aero/init_water_coupled_to_tank_ with_sloshing.k uses penalty-based *constrained_lagrange_in_solid to couple the water to the tank. The two figures below show similar results from the two simulations.Modeling Inflow and Outflow ConditionsIn addition to setting ELFORM to 11, setting AET to 4 in *section_solid invokes a reservoir (or ambient) type element option in the ALE formulation. The user may dictate pressure to such elements by prescribing the thermodynamic condition of the element, either as unvarying with time by simply defining E0 and V0 in the *eos (equation-of-state) input or as a function of time via *boundary_ambient_eos. Thus to model a prescribed inflow or prescribed outflow of material, one or two layers of ALE elements on the exterior of the mesh at the inflow (outflow) region is assigned a unique PART ID so that AET may be set to 4 for that layer. If the inflow or outflow conditions include a known flow velocity into or out of the ALE mesh, that velocity is prescribed by applying *boundary_prescribed_motion_node to the exterior nodes at theinflow/outflow region.To model unprescribed (unknown) outflow, AET may be left as 0 (default) in which case outflow is calculated by LS-DYNA.Do not attempt to assign values other than 0 or 4 to the parameter AET.An example illustrating prescribed inflow is found at/anonymous/outgoing/jday/aero/purge.ambient.mod.k . The following three figures show snapshots of the simulation. In this example, inflow of water into an empty container is diverted by a rubber flap modeled with Lagrangian solids. The rigid “container” is simulated via nodal constraints, i.e., the container is not represented by elements. An egress hole in the container is included by leaving some of the exterior nodes in the lower righthand corner unconstrained in the horizontal direction. By virtue of their ambient inflow designation(AET=4), the pressure is prescribed in the top layer of elements and that, together with gravity loading, serves to drive the simulation. Because *boundary_ambient_eos is not used in this example, the prescribed pressure in the ambient elements is a constant value, determined from the initial condition parameters in the equation-of-state.Initializing Pressure in ALE MaterialsIn many situations, an initial pressure field in one or more of the ALE materials in known, e.g., atmospheric pressure in air or hydrostatic pressure in water. If the pressure field is uniform as in air at atmospheric pressure, EO and V0 in the *eos input is sufficient to initialize the pressure. In such a case, as mentioned earlier, exterior segments must also have an applied pressure to equilibrate the internal pressure, either via *load_segment or via PREF in *control_ale.In the more complex case where pressure varies with depth as in the case of water, the command *initial_hydrostatic_ale can be used as an aid to greatly reduce the time it takes to initialize the hydrostatic pressure and reach a steady state condition in the fluid./anonymous/outgoing/jday/aero/f_damp300_bub.k is an example of a pool-like condition without inflow or outflow conditions. Here, a gas bubble initially resides below the surface of the water as shown in the figure below.*Initial_hydrostatic_ale, in conjunction with *load_body, which applies gravity loading, and*boundary_spc, which applies the normal direction constraints to the pool walls and pool bottom, serves to quickly initialize the hydrostatic state of the fluids. In addition, this exampleemploys mass damping (*damping_part_mass) to remove the oscillations in pressure time histories that are otherwise seen when no damping is employed. The damping is specified as a function of time and is set to zero after achieving a steady state condition (t = 0.08 in this example) soas not to inhibit physical motion thereafter. If the termination time in the example is extended from 0.2 to 2.0, such motion is clearly evident in the form of the gas bubble rising and changing shape. Note that when mass damping is used, the value should be derived from the period of oscillation T, recognizing that critical damping is equal to 4*pi/T. Figures showing the early time results of the example are provided below. For more details of the example and of*initial_hydrostatic_ale command syntax, see pp. 14-25 of/anonymous/outgoing/jday/aero/21_hydro_p_initialization_34p.pdf.。

非线性偏微分方程

FINITE DIMENSIONAL REDUCTION OF NONAUTONOMOUS DISSIPATIVESYSTEMSAlain MiranvilleUniversit´e de Poitiers Collaborators:Long time behavior of equations of the formy′=F(t,y)For autonomous systems:y′=F(y)In many situations,the evolution of the sys-tem is described by a system of ODEs:y=(y1,...,y N)∈R N,F=(F1,...,F N)Assuming that the Cauchy problemy′=F(y),y(0)=y0,is well-posed,we can deﬁne the family of solv-ing operators S(t),t≥0,acting on a subset φ⊂R N:S(t):φ→φy0→y(t)This family of operators satisﬁesS(0)=Id,S(t+s)=S(t)◦S(s),t,s≥0We say that it forms a semigroup onφQualitative study of such systems:goes back to Poincar´eMuch is known nowadays,at least in low di-mensionsEven relatively simple systems can generate very complicated chaotic behaviorsThese systems are sensitive to perturbations: trajectories with close initial data may diverge exponentially→Temporal evolution unpredictable on ti-me scales larger than some critical value→Show typical stochastic behaviorsExample:Lorenz systemx′=σ(y−x)y′=−xy+rx−yz′=xy−bzObtained by truncature of the Navier-Stokes equationsGives an approximate description of a layer of ﬂuid heated from belowSimilar to what is observed in the atmosphereFor a suﬃciently intense heating:sensitive dependence on the initial conditions,repre-sents a very irregular convection→Butterﬂy eﬀectVery often,the trajectories are localized in some subset of the phase space having a very complicated geometric structure(e.g.,locally homeomorphic to the product of R m and a Cantor set)→Strange attractor(Ruelle and Takens)Main feature of a strange attractor:dimen-sionSensitivity to initial conditions:>2(dimen-sion of the phase space≥3,say,3)Contraction of volumes:its volume is equal to0→noninteger,strictly between2and3→Fractal dimensionExample:Lorenz system:dim F A=2.05...Distributed systems:systems of PDEsφis a subset of an inﬁnite dimensional func-tion space(e.g.,L2(Ω)or L∞(Ω))Solution:y:R+→φt→y(t)x→y(t,x)If the problem is well-posed,we can deﬁne the semigroup S(t):S(t):φ→φy0→y(t)The analytic structure of a PDE is much more complicated than that of an ODE:the global well-posedness can be a very diﬃcult problemSuch results are known for a large class of PDEs→it is natural to investigate whether the notion of a strange attractor extends to PDEsSuch chaotic behaviors can be observed in dissipative PDEsChaotic behaviors arise from the interaction of•Energy dissipation in the higher part of the Fourier spectrum•External energy income in the lower part•Energyﬂux from the lower to the higher modesThe trajectories are localized in a”thin”in-variant region of the phase space having a very complicated geometric structure→the global attractor1.The global attractor.S(t)semigroup acting on E:S(t):E→E,t≥0S(0)=Id,S(t+s)=S(t)◦S(s),t,s≥0 Continuity:x→S(t)x is continuous on E,∀t≥0A set A⊂E is the global attractor for S(t)if(i)it is compact(ii)it is invariant:S(t)A=A,t≥0(iii)∀B⊂A,lim t→+∞dist(S(t)B,A)=0dist(A,B)=supa∈A infb∈Ba−b EEquivalently:∀B⊂φbounded,∀ǫ>0,∃t0= t0(B,ǫ)s.t.t≥t0implies S(t)B⊂UǫThe global attractor is uniqueIt is the smallest closed set enjoying(iii)It is the maximal bounded invariant setTheorem:(Babin-Vishik)We assume that S(t)possesses a compact attracting set K, i.e.,∀B⊂E bounded,lim t→+∞dist(S(t)B,K)=0Then S(t)possesses the global attractor A.The global attractor is oftenﬁnite dimen-sional:the dynamics,restricted to A isﬁnite dimensionalFractal dimension:Let X be a compact setdim F X=lim supǫ→0+ln Nǫ(X)ǫNǫ(X):minimum number of balls of radius ǫnecessary to cover XIf Nǫ(X)≤c(1Theorem:(H¨o lder-Ma˜n´e theorem)Let X⊂E compact satisfy dim F X=d and N>2d be an integer.Then almost every bounded linear projector P:E→R N is one-to-one on X and has a H¨o lder continuous inverse.This result is not valid for other dimensions (e.g.,the Hausdorﬀdimension)If A hasﬁnite fractal dimension,then,ﬁxing a projector P satisfying the assumptions of the theorem,we obtain a reduced dynamical system(S),S= P(A),which isﬁnite dimensional(in R N)and H¨o lder continuousDrawbacks:(S)cannot be realized as a system of ODEs which is well-posedReasonable assumptions on A which would ensure that the Ma˜n´e projectors are Lipschitz are not knownComplicated geometric structure of A and AThe lower semicontinuitydist(A0,Aǫ)→0asǫ→0is more diﬃcult to prove and may not hold It may be unobservable:∂y∂x2+y3−y=0,x∈[0,1],ν>0y(0,t)=y(1,t)=−1,t≥0A={−1}There are many metastable”almost station-ary”equilibria which live up to t⋆≡eν−12.Inertial manifolds.A Lipschitzﬁnite dimensional manifold M⊂E is an inertial manifold for S(t)if(i)S(t)M⊂M,∀t≥0(ii)∀u0∈E,∃v0∈M s.t.S(t)u0−S(t)v0 E≤Q( u0 E)e−αt,α>0,Q monotonicM contains A and attracts the trajectories exponentiallyConﬁrms in a perfect way theﬁnite dimen-sional reduction principle:The dynamics reduced to M can be realized as a Lipschitz system of ODEs(inertial form)Perfect equivalence between the initial sys-tem and the inertial formDrawback:all the known constructions are based on a restrictive condition,the spectral gap condition→The existence of an inertial manifold is not known for several important equations, nonexistence results for damped Sine-Gordon equations3.Exponential attractors.A compact set M⊂E is an exponential at-tractor for S(t)if(i)It hasﬁnite fractal dimension(ii)S(t)M⊂M,∀t≥0(iii)∀B⊂E bounded,dist(S(t)B,M)≤Q( B E)e−αt,α>0,Q monotonicM contains AIt is stillﬁnite dimensional and one has a uni-form exponential control on the rate of at-traction of trajectoriesIt is no longer smoothDrawback:it is not unique→One looks for a simple algorithm S→M(S)Initial construction:non-constructible and valid in Hilbert spaces onlyConstruction in Banach spaces:Efendiev, Miranville,Zelik→Exponential attractors are as general as global attractorsMain tool:Compact smoothing property on the diﬀerence of2solutionsLet S:E→E.We consider the discrete dynamical system generated by the iterations of S:S n=S◦...◦S(n times)Theorem:(Efendiev,Miranville,Zelik)We consider2Banach spaces E and E1s.t.E1⊂E is compact.We assume that•S maps theδ-neighborhood Oδ(B)of a bounded subset B of E into B•∀x1,x2∈Oδ(B),≤K x1−x2 ESx1−Sx2 E1Then the discrete dynamical system gener-ated by the iterations of S possesses an ex-ponential attractor M(S)s.t.(i)M(S)⊂B,is compact in E anddim F M(S)≤c1(ii)S M(S)⊂M(S)(iii)dist(S k B,M(S))≤c2e−c3k,k∈N,c3>0 (iv)The map S→M(S)is H¨o lder continu-ous:∀S1,S2,dist sym(M(S1),M(S2))≤c4 S1−S2 c5,c5>0, wheredist sym(A,B)=max(dist(A,B),dist(B,A))S =supSh Eh∈Oδ(B)Furthermore all the constants only depend on B,E,E1,δand K and can be computed explicitly.Remarks:1)We have a mapping S→M(S)and,due to the H¨o lder continuity,we can construct continuous families of exponential attractors2)Exponential attractors for a continuous semigroup S(t):Prove that∃t⋆>0s.t.S⋆=S(t⋆)satisﬁes the assumptions of the theorem→M⋆for S⋆If(x,t)→S(t)x is Lipschitz(or H¨o lder)on B×[0,t⋆],setS(t)M⋆M=∪t∈[0,t⋆]We again have a mapping S(t)→M(S)which is H¨o lder continuous3)For damped hyperbolic equations:asymp-totically smoothing property4.Finite dimensional reduction of nonau-tonomous systems.Systems of the form∂yDrawback:the uniform attractor has inﬁnite dimension in general.Example:∂yThe family{A(t),t∈R}is a pullback attrac-tor for U(t,τ)if(i)A(t)is compact in E,∀t∈R(ii)U(t,τ)A(τ)=A(t),∀t≥τ(iii)∀B⊂E bounded,dist(U(t,t−s)B,A(t))=0lims→+∞Remarks:1)The pullback attractor is unique2)If the system is autonomous,we recover the global attractor3)In general,A(t)hasﬁnite fractal dimen-sion,∀t∈RDrawback:The forward convergence does not hold in generalExample:y′=f(t,y),where f(t,y)=−y if y≤0,(−1+2t)y−ty2 if t∈[0,1],and y−y2if t≥1Then A(t)={0},∀t∈R,but every trajectory starting from a neighborhood of0leaves this neighborhood never to enter it againThe forward convergence does not hold be-cause the rate of attraction is not uniform in t→This can be solved by constructing ex-ponential attractorsWe can construct a family{M(t),t∈R}, called nonautonomous exponential attractor, s.t.(i)dim F M(t)≤c1,∀t∈R,c1independent of t(ii)U(t,τ)M(τ)⊂M(t),∀t≥τ,(iii)∀B⊂E bounded,dist(U(t,τ)B,M(t+τ))≤Q( B E)e−αt,t∈R,t≥τ,α>0,Q monotonic(iii)implies the pullback attraction,but also the forward attraction→(i)and(iii)yield a satisfactoryﬁnite di-mensional reduction principle for nonautono-mous systemsRemarks:1)The time dependence is arbitrary2)The map U(t,τ)→{M(t),t∈R}is also H¨o lder continuous。

非厄米算符对易关系

非厄米算符对易关系Quantum mechanics plays a fundamental role in understanding the behavior of particles at the tiny scales of atoms and subatomic particles. One of the key concepts in quantum mechanics is the notion of operators, which are mathematical objects that represent physical observables in the theory. In particular, the notion of a Hermitian operator, which corresponds to observable quantities in the physical world, is crucial to the theory. However, not all operators are Hermitian, and non-Hermitian operators can also play a role in quantum mechanics.量子力学在理解原子和亚原子粒子微观尺度行为方面起着基础性作用。

量子力学的一个关键概念是算符的概念，算符是代表理论中物理可观测量的数学对象。

特别是，埃尔米特算符的概念，它对应着物理世界中的可观测量，对于理论起着至关重要的作用。

然而，并非所有算符都是埃尔米特的，非埃尔米特算符也可以在量子力学中发挥作用。

In quantum mechanics, the observables are represented by Hermitian operators, which are essential for the statistical interpretation of the theory. Hermitian operators have realeigenvalues, which correspond to the possible measurement outcomes of physical quantities. However, non-Hermitian operators can also be used to describe certain physical systems, especially those involving open quantum systems or interactions with the environment. Although non-Hermitian operators do not correspond to observables in the same way as Hermitian operators, they can still provide important insights into the behavior of quantum systems.在量子力学中，可观测量由埃尔米特算符表示，这对于理论的统计解释至关重要。

Knowledge Engineering-Principles And Methods

Knowledge Engineering:Principles and MethodsRudi Studer1, V. Richard Benjamins2, and Dieter Fensel11Institute AIFB, University of Karlsruhe, 76128 Karlsruhe, Germany{studer, fensel}@aifb.uni-karlsruhe.dehttp://www.aifb.uni-karlsruhe.de2Artificial Intelligence Research Institute (IIIA),Spanish Council for Scientific Research (CSIC), Campus UAB,08193 Bellaterra, Barcelona, Spainrichard@iiia.csic.es, http://www.iiia.csic.es/~richard2Dept. of Social Science Informatics (SWI),richard@swi.psy.uva.nl, http://www.swi.psy.uva.nl/usr/richard/home.htmlAbstractThis paper gives an overview about the development of the field of Knowledge Engineering over the last 15 years. We discuss the paradigm shift from a transfer view to a modeling view and describe two approaches which considerably shaped research in Knowledge Engineering: Role-limiting Methods and Generic Tasks. To illustrate various concepts and methods which evolved in the last years we describe three modeling frameworks: CommonKADS, MIKE, and PROTÉGÉ-II. This description is supplemented by discussing some important methodological developments in more detail: specification languages for knowledge-based systems, problem-solving methods, and ontologies. We conclude with outlining the relationship of Knowledge Engineering to Software Engineering, Information Integration and Knowledge Management.Key WordsKnowledge Engineering, Knowledge Acquisition, Problem-Solving Method, Ontology, Information Integration1IntroductionIn earlier days research in Artificial Intelligence (AI) was focused on the development offormalisms, inference mechanisms and tools to operationalize Knowledge-based Systems (KBS). Typically, the development efforts were restricted to the realization of small KBSs in order to study the feasibility of the different approaches.Though these studies offered rather promising results, the transfer of this technology into commercial use in order to build large KBSs failed in many cases. The situation was directly comparable to a similar situation in the construction of traditional software systems, called …software crisis“ in the late sixties: the means to develop small academic prototypes did not scale up to the design and maintenance of large, long living commercial systems. In the same way as the software crisis resulted in the establishment of the discipline Software Engineering the unsatisfactory situation in constructing KBSs made clear the need for more methodological approaches.So the goal of the new discipline Knowledge Engineering (KE) is similar to that of Software Engineering: turning the process of constructing KBSs from an art into an engineering discipline. This requires the analysis of the building and maintenance process itself and the development of appropriate methods, languages, and tools specialized for developing KBSs. Subsequently, we will first give an overview of some important historical developments in KE: special emphasis will be put on the paradigm shift from the so-called transfer approach to the so-called modeling approach. This paradigm shift is sometimes also considered as the transfer from first generation expert systems to second generation expert systems [43]. Based on this discussion Section 2 will be concluded by describing two prominent developments in the late eighties:Role-limiting Methods [99] and Generic Tasks [36]. In Section 3 we will present some modeling frameworks which have been developed in recent years: CommonKADS [129], MIKE [6], and PROTÈGÈ-II [123]. Section 4 gives a short overview of specification languages for KBSs. Problem-solving methods have been a major research topic in KE for the last decade. Basic characteristics of (libraries of) problem-solving methods are described in Section 5. Ontologies, which gained a lot of importance during the last years are discussed in Section 6. The paper concludes with a discussion of current developments in KE and their relationships to other disciplines.In KE much effort has also been put in developing methods and supporting tools for knowledge elicitation (compare [48]). E.g. in the VITAL approach [130] a collection of elicitation tools, like e.g. repertory grids (see [65], [83]), are offered for supporting the elicitation of domain knowledge (compare also [49]). However, a discussion of the various elicitation methods is beyond the scope of this paper.2Historical Roots2.1Basic NotionsIn this section we will first discuss some main principles which characterize the development of KE from the very beginning.Knowledge Engineering as a Transfer Process…This transfer and transformation of problem-solving expertise from a knowledge source to a program is the heart of the expert-system development process.” [81]In the early eighties the development of a KBS has been seen as a transfer process of humanknowledge into an implemented knowledge base. This transfer was based on the assumption that the knowledge which is required by the KBS already exists and just has to be collected and implemented. Most often, the required knowledge was obtained by interviewing experts on how they solve speciﬁc tasks [108]. Typically, this knowledge was implemented in some kind of production rules which were executed by an associated rule interpreter. However, a careful analysis of the various rule knowledge bases showed that the rather simple representation formalism of production rules did not support an adequate representation of different types of knowledge [38]: e.g. in the MYCIN knowledge base [44] strategic knowledge about the order in which goals should be achieved (e.g. “consider common causes of a disease first“) is mixed up with domain specific knowledge about for example causes for a specific disease. This mixture of knowledge types, together with the lack of adequate justifications of the different rules, makes the maintenance of such knowledge bases very difficult and time consuming. Therefore, this transfer approach was only feasible for the development of small prototypical systems, but it failed to produce large, reliable and maintainable knowledge bases.Furthermore, it was recognized that the assumption of the transfer approach, that is that knowledge acquisition is the collection of already existing knowledge elements, was wrong due to the important role of tacit knowledge for an expert’s problem-solving capabilities. These deficiencies resulted in a paradigm shift from the transfer approach to the modeling approach.Knowledge Engineering as a Modeling ProcessNowadays there exists an overall consensus that the process of building a KBS may be seen as a modeling activity. Building a KBS means building a computer model with the aim of realizing problem-solving capabilities comparable to a domain expert. It is not intended to create a cognitive adequate model, i.e. to simulate the cognitive processes of an expert in general, but to create a model which offers similar results in problem-solving for problems in the area of concern. While the expert may consciously articulate some parts of his or her knowledge, he or she will not be aware of a significant part of this knowledge since it is hidden in his or her skills. This knowledge is not directly accessible, but has to be built up and structured during the knowledge acquisition phase. Therefore this knowledge acquisition process is no longer seen as a transfer of knowledge into an appropriate computer representation, but as a model construction process ([41], [106]).This modeling view of the building process of a KBS has the following consequences:•Like every model, such a model is only an approximation of the reality. In principle, the modeling process is inﬁnite, because it is an incessant activity with the aim of approximating the intended behaviour.•The modeling process is a cyclic process. New observations may lead to a reﬁnement, modiﬁcation, or completion of the already built-up model. On the other side, the model may guide the further acquisition of knowledge.•The modeling process is dependent on the subjective interpretations of the knowledge engineer. Therefore this process is typically faulty and an evaluation of the model with respect to reality is indispensable for the creation of an adequate model. According to this feedback loop, the model must therefore be revisable in every stage of the modeling process.Problem Solving MethodsIn [39] Clancey reported on the analysis of a set of first generation expert systems developed to solve different tasks. Though they were realized using different representation formalisms (e.g. production rules, frames, LISP), he discovered a common problem solving behaviour.Clancey was able to abstract this common behaviour to a generic inference pattern called Heuristic Classification , which describes the problem-solving behaviour of these systems on an abstract level, the so called Knowledge Level [113]. This knowledge level allows to describe reasoning in terms of goals to be achieved, actions necessary to achieve these goals and knowledge needed to perform these actions. A knowledge-level description of a problem-solving process abstracts from details concerned with the implementation of the reasoning process and results in the notion of a Problem-Solving Method (PSM).A PSM may be characterized as follows (compare [20]):• A PSM speciﬁes which inference actions have to be carried out for solving a given task.• A PSM determines the sequence in which these actions have to be activated.•In addition, so-called knowledge roles determine which role the domain knowledge plays in each inference action. These knowledge roles deﬁne a domain independent generic terminology.When considering the PSM Heuristic Classification in some more detail (Figure 1) we can identify the three basic inference actions abstract ,heuristic match , and refine . Furthermore,four knowledge roles are defined:observables ,abstract observables ,solution abstractions ,and solutions . It is important to see that such a description of a PSM is given in a generic way.Thus the reuse of such a PSM in different domains is made possible. When considering a medical domain, an observable like …410 C“ may be abstracted to …high temperature“ by the inference action abstract . This abstracted observable may be matched to a solution abstraction, e.g. …infection“, and finally the solution abstraction may be hierarchically refined to a solution, e.g. the disease …influenca“.In the meantime various PSMs have been identified, like e.g.Cover-and-Differentiate for solving diagnostic tasks [99] or Propose-and-Revise [100] for parametric design tasks.PSMs may be exploited in the knowledge engineering process in different ways:Fig. 1 The Problem-Solving Method Heuristic Classiﬁcationroleinference action•PSMs contain inference actions which need speciﬁc knowledge in order to perform their task. For instance,Heuristic Classiﬁcation needs a hierarchically structured model of observables and solutions for the inference actions abstract and reﬁne, respectively.So a PSM may be used as a guideline to acquire static domain knowledge.• A PSM allows to describe the main rationale of the reasoning process of a KBS which supports the validation of the KBS, because the expert is able to understand the problem solving process. In addition, this abstract description may be used during the problem-solving process itself for explanation facilities.•Since PSMs may be reused for developing different KBSs, a library of PSMs can be exploited for constructing KBSs from reusable components.The concept of PSMs has strongly stimulated research in KE and thus has influenced many approaches in this area. A more detailed discussion of PSMs is given in Section 5.2.2Speciﬁc ApproachesDuring the eighties two main approaches evolved which had significant influence on the development of modeling approaches in KE: Role-Limiting Methods and Generic Tasks. Role-Limiting MethodsRole-Limiting Methods (RLM) ([99], [102]) have been one of the first attempts to support the development of KBSs by exploiting the notion of a reusable problem-solving method. The RLM approach may be characterized as a shell approach. Such a shell comes with an implementation of a specific PSM and thus can only be used to solve a type of tasks for which the PSM is appropriate. The given PSM also defines the generic roles that knowledge can play during the problem-solving process and it completely fixes the knowledge representation for the roles such that the expert only has to instantiate the generic concepts and relationships, which are defined by these roles.Let us consider as an example the PSM Heuristic Classification (see Figure 1). A RLM based on Heuristic Classification offers a role observables to the expert. Using that role the expert (i) has to specify which domain specific concept corresponds to that role, e.g. …patient data”(see Figure 4), and (ii) has to provide domain instances for that concept, e.g. concrete facts about patients. It is important to see that the kind of knowledge, which is used by the RLM, is predefined. Therefore, the acquisition of the required domain specific instances may be supported by (graphical) interfaces which are custom-tailored for the given PSM.In the following we will discuss one RLM in some more detail: SALT ([100], [102]) which is used for solving constructive tasks.Then we will outline a generalization of RLMs to so-called Configurable RLMs.SALT is a RLM for building KBSs which use the PSM Propose-and-Revise. Thus KBSs may be constructed for solving specific types of design tasks, e.g. parametric design tasks. The basic inference actions that Propose-and-Revise is composed of, may be characterized as follows:•extend a partial design by proposing a value for a design parameter not yet computed,•determine whether all computed parameters fulﬁl the relevant constraints, and•apply ﬁxes to remove constraint violations.In essence three generic roles may be identified for Propose-and-Revise ([100]):•…design-extensions” refer to knowledge for proposing a new value for a design parameter,•…constraints” provide knowledge restricting the admissible values for parameters, and •…ﬁxes” make potential remedies available for speciﬁc constraint violations.From this characterization of the PSM Propose-and-Revise, one can easily see that the PSM is described in generic, domain-independent terms. Thus the PSM may be used for solving design tasks in different domains by specifying the required domain knowledge for the different predefined generic knowledge roles.E.g. when SALT was used for building the VT-system [101], a KBS for configuring elevators, the domain expert used the form-oriented user interface of SALT for entering domain specific design extensions (see Figure 2). That is, the generic terminology of the knowledge roles, which is defined by object and relation types, is instantiated with VT specific instances.1Name:CAR-JAMB-RETURN2Precondition:DOOR-OPENING = CENTER3Procedure:CALCULATION4Formula:[PLATFORM-WIDTH -OPENING-WIDTH] / 25Justiﬁcation:CENTER-OPENING DOORS LOOKBEST WHEN CENTERED ONPLATFORM.(the value of the design parameter CAR-JUMB-RETURN iscalculated according to the formula - in case the preconditionis fulﬁlled; the justiﬁcation gives a description why thisparameter value is preferred over other values (example takenfrom [100]))Fig. 2 Design Extension Knowledge for VTOn the one hand, the predefined knowledge roles and thus the predefined structure of the knowledge base may be used as a guideline for the knowledge acquisition process: it is clearly specified what kind of knowledge has to be provided by the domain expert. On the other hand, in most real-life situations the problem arises of how to determine whether a specific task may be solved by a given RLM. Such task analysis is still a crucial problem, since up to now there does not exist a well-defined collection of features for characterizing a domain task in a way which would allow a straightforward mapping to appropriate RLMs. Moreover, RLMs have a fixed structure and do not provide a good basis when a particular task can only be solved by a combination of several PSMs.In order to overcome this inflexibility of RLMs, the concept of configurable RLMs has been proposed.Configurable Role-Limiting Methods (CRLMs) as discussed in [121] exploit the idea that a complex PSM may be decomposed into several subtasks where each of these subtasks may be solved by different methods (see Section 5). In [121], various PSMs for solving classification tasks, like Heuristic Classification or Set-covering Classification, have been analysed with respect to common subtasks. This analysis resulted in the identification ofshared subtasks like …data abstraction” or …hypothesis generation and test”. Within the CRLM framework a predefined set of different methods are offered for solving each of these subtasks. Thus a PSM may be configured by selecting a method for each of the identified subtasks. In that way the CRLM approach provides means for configuring the shell for different types of tasks. It should be noted that each method offered for solving a specific subtask, has to meet the knowledge role specifications that are predetermined for the CRLM shell, i.e. the CRLM shell comes with a fixed scheme of knowledge types. As a consequence, the introduction of a new method into the shell typically involves the modification and/or extension of the current scheme of knowledge types [121]. Having a fixed scheme of knowledge types and predefined communication paths between the various components is an important restriction distinguishing the CRLM framework from more flexible configuration approaches such as CommonKADS (see Section 3).It should be clear that the introduction of such flexibility into the RLM approach removes one of its disadvantages while still exploiting the advantage of having a fixed scheme of knowledge types, which build the basis for generating effective knowledge-acquisition tools. On the other hand, configuring a CRLM shell increases the burden for the system developer since he has to have the knowledge and the ability to configure the system in the right way. Generic Task and Task StructuresIn the early eighties the analysis and construction of various KBSs for diagnostic and design tasks evolved gradually into the notion of a Generic Task (GT) [36]. GTs like Hierarchical Classification or State Abstraction are building blocks which can be reused for the construction of different KBSs.The basic idea of GTs may be characterized as follows (see [36]):• A GT is associated with a generic description of its input and output.• A GT comes with a ﬁxed scheme of knowledge types specifying the structure of domain knowledge needed to solve a task.• A GT includes a ﬁxed problem-solving strategy specifying the inference steps the strategy is composed of and the sequence in which these steps have to be carried out. The GT approach is based on the strong interaction problem hypothesis which states that the structure and representation of domain knowledge is completely determined by its use [33]. Therefore, a GT comes with both, a fixed problem-solving strategy and a fixed collection of knowledge structures.Since a GT fixes the type of knowledge which is needed to solve the associated task, a GT provides a task specific vocabulary which can be exploited to guide the knowledge acquisition process. Furthermore, by offering an executable shell for a GT, called a task specific architecture, the implementation of a specific KBS could be considered as the instantiation of the predefined knowledge types by domain specific terms (compare [34]). On a rather pragmatic basis several GTs have been identified including Hierarchical Classification,Abductive Assembly and Hypothesis Matching. This initial collection of GTs was considered as a starting point for building up an extended collection covering a wide range of relevant tasks.However, when analyzed in more detail two main disadvantages of the GT approach have been identified (see [37]):•The notion of task is conﬂated with the notion of the PSM used to solve the task, sinceeach GT included a predetermined problem-solving strategy.•The complexity of the proposed GTs was very different, i.e. it remained open what the appropriate level of granularity for the building blocks should be.Based on this insight into the disadvantages of the notion of a GT, the so-called Task Structure approach was proposed [37]. The Task Structure approach makes a clear distinction between a task, which is used to refer to a type of problem, and a method, which is a way to accomplish a task. In that way a task structure may be defined as follows (see Figure 3): a task is associated with a set of alternative methods suitable for solving the task. Each method may be decomposed into several subtasks. The decomposition structure is refined to a level where elementary subtasks are introduced which can directly be solved by using available knowledge.As we will see in the following sections, the basic notion of task and (problem-solving)method, and their embedding into a task-method-decomposition structure are concepts which are nowadays shared among most of the knowledge engineering methodologies.3Modeling FrameworksIn this section we will describe three modeling frameworks which address various aspects of model-based KE approaches: CommonKADS [129] is prominent for having defined the structure of the Expertise Model, MIKE [6] puts emphasis on a formal and executable specification of the Expertise Model as the result of the knowledge acquisition phase, and PROTÉGÉ-II [51] exploits the notion of ontologies.It should be clear that there exist further approaches which are well known in the KE community, like e.g VITAL [130], Commet [136], and EXPECT [72]. However, a discussion of all these approaches is beyond the scope of this paper.Fig. 3 Sample Task Structure for DiagnosisTaskProblem-Solving MethodSubtasksProblem-Solving MethodTask / Subtasks3.1The CommonKADS ApproachA prominent knowledge engineering approach is KADS[128] and its further development to CommonKADS [129]. A basic characteristic of KADS is the construction of a collection of models, where each model captures specific aspects of the KBS to be developed as well as of its environment. In CommonKADS the Organization Model, the Task Model, the Agent Model, the Communication Model, the Expertise Model and the Design Model are distinguished. Whereas the first four models aim at modeling the organizational environment the KBS will operate in, as well as the tasks that are performed in the organization, the expertise and design model describe (non-)functional aspects of the KBS under development. Subsequently, we will briefly discuss each of these models and then provide a detailed description of the Expertise Model:•Within the Organization Model the organizational structure is described together with a speciﬁcation of the functions which are performed by each organizational unit.Furthermore, the deﬁciencies of the current business processes, as well as opportunities to improve these processes by introducing KBSs, are identiﬁed.•The Task Model provides a hierarchical description of the tasks which are performed in the organizational unit in which the KBS will be installed. This includes a speciﬁcation of which agents are assigned to the different tasks.•The Agent Model speciﬁes the capabilities of each agent involved in the execution of the tasks at hand. In general, an agent can be a human or some kind of software system, e.g.a KBS.•Within the Communication Model the various interactions between the different agents are speciﬁed. Among others, it speciﬁes which type of information is exchanged between the agents and which agent is initiating the interaction.A major contribution of the KADS approach is its proposal for structuring the Expertise Model, which distinguishes three different types of knowledge required to solve a particular task. Basically, the three different types correspond to a static view, a functional view and a dynamic view of the KBS to be built (see in Figure 4 respectively “domain layer“, “inference layer“ and “task layer“):•Domain layer : At the domain layer all the domain speciﬁc knowledge is modeled which is needed to solve the task at hand. This includes a conceptualization of the domain in a domain ontology (see Section 6), and a declarative theory of the required domain knowledge. One objective for structuring the domain layer is to model it as reusable as possible for solving different tasks.•Inference layer : At the inference layer the reasoning process of the KBS is speciﬁed by exploiting the notion of a PSM. The inference layer describes the inference actions the generic PSM is composed of as well as the roles , which are played by the domain knowledge within the PSM. The dependencies between inference actions and roles are speciﬁed in what is called an inference structure. Furthermore, the notion of roles provides a domain independent view on the domain knowledge. In Figure 4 (middle part) we see the inference structure for the PSM Heuristic Classiﬁcation . Among others we can see that …patient data” plays the role of …observables” within the inference structure of Heuristic Classiﬁcation .•Task layer : The task layer provides a decomposition of tasks into subtasks and inference actions including a goal speciﬁcation for each task, and a speciﬁcation of how theseFig. 4 Expertise Model for medical diagnosis (simpliﬁed CML notation)goals are achieved. The task layer also provides means for specifying the control over the subtasks and inference actions, which are deﬁned at the inference layer.Two types of languages are offered to describe an Expertise Model: CML (Conceptual Modeling Language) [127], which is a semi-formal language with a graphical notation, and (ML)2 [79], which is a formal specification language based on first order predicate logic, meta-logic and dynamic logic (see Section 4). Whereas CML is oriented towards providing a communication basis between the knowledge engineer and the domain expert, (ML)2 is oriented towards formalizing the Expertise Model.The clear separation of the domain specific knowledge from the generic description of the PSM at the inference and task layer enables in principle two kinds of reuse: on the one hand, a domain layer description may be reused for solving different tasks by different PSMs, on the other hand, a given PSM may be reused in a different domain by defining a new view to another domain layer. This reuse approach is a weakening of the strong interaction problem hypothesis [33] which was addressed in the GT approach (see Section 2). In [129] the notion of a relative interaction hypothesis is defined to indicate that some kind of dependency exists between the structure of the domain knowledge and the type of task which should be solved. To achieve a flexible adaptation of the domain layer to a new task environment, the notion of layered ontologies is proposed:Task and PSM ontologies may be defined as viewpoints on an underlying domain ontology.Within CommonKADS a library of reusable and configurable components, which can be used to build up an Expertise Model, has been defined [29]. A more detailed discussion of PSM libraries is given in Section 5.In essence, the Expertise Model and the Communication Model capture the functional requirements for the target system. Based on these requirements the Design Model is developed, which specifies among others the system architecture and the computational mechanisms for realizing the inference actions. KADS aims at achieving a structure-preserving design, i.e. the structure of the Design Model should reflect the structure of the Expertise Model as much as possible [129].All the development activities, which result in a stepwise construction of the different models, are embedded in a cyclic and risk-driven life cycle model similar to Boehm’s spiral model [21].The basic structure of the expertise model has some similarities with the data, functional, and control view of a system as known from software engineering. However, a major difference may be seen between an inference layer and a typical data-flow diagram (compare [155]): Whereas an inference layer is specified in generic terms and provides - via roles and domain views - a flexible connection to the data described at the domain layer, a data-flow diagram is completely specified in domain specific terms. Moreover, the data dictionary does not correspond to the domain layer, since the domain layer may provide a complete model of the domain at hand which is only partially used by the inference layer, whereas the data dictionary is describing exactly those data which are used to specify the data flow within the data flow diagram (see also [54]).3.2The MIKE ApproachThe MIKE approach (Model-based and Incremental Knowledge Engineering) (cf. [6], [7])。

2023-2024学年浙江省杭州市新东方高二上期末考英语试题03

2023-2024学年浙江省杭州市新东方高二上期末考英语试题03Best Alternatives of Top Travel Booking SitesAfter losing two precious years to COVID, everybody is desperate to travel and explore the world. However, planning a dream trip is not easy as it demands carefully spending your money on flights and accommodation. Let’s see what best travel booking sites in the UK has to offer and what alternatives we have:TravelhouseukIt has been dedicated to serving its important clients for more than two decades now by using the expertise of travel agents. It is an element of human interaction with your travel agent that allows you to discuss your requirements in depth for personalization and look for customer support even after the booking is made.SkyscannerIt is a user-friendly interface that compares flight prices from all over the globe and brings out the best deals on flights. Not only flights but you can use this metasearch engine for hotels and car rentals too. It is a great tool for everyone, but some alternatives may help you even better in finding the cheapest trip to your destination.Cheap FlightsWhen Skyscanner considers known carriers to maintain the quality, Cheapflights takes the lead with the cheapest flight options worldwide. The online site serves up the cheapest time to fly, reasonable hotel rates, low-cost car rentals and vacation packages. The aim is to promote and simplify your travel experience by offering it all in one place.Google FlightsIt is a renowned name that facilitates online sales of air ticket through third-party suppliers. The best feature of using Google Flights is based on no predetermined time limits. You can look for the cheapest flying dates within the next two months of search dates.1. What makes Travelhouseuk special?A．Its price. B．Its convenience.C．Its booking time. D．Its personalized service.2. Which travel agency can you choose if you want to drive?A．Travelhouseuk and Google Flights. B．Google Flights and Cheap Flights.C．Skyscanner and Cheap Flights. D．Cheap Flights and Travelhouseuk.3. In which part of the web can you read this article?A．Travel. B．Culture. C．Lifestyle. D．Business.Several security guards of residential compounds in Beijing and workers were seen shoveling snow and some parked vehicles were covered by thick overnight snow. The first snowfall of winter arrived in Beijing early Monday, covering the Chinese capital with a mantle (披风) of white overnight and plunging (使……下降) the city into freezing temperatures, with even colder weather coming this week in northern China.Snowfall reached 5.8 mm on average by early Monday, with the highest snowfall of 10.2 mm recorded in Fangshan district, Beijing Meteorological (气象的) Service data showed. Beijing typically sees its first snow of the season between late November and February, or even none at all. More snowfall is expected this week, with temperatures seen further sliding to as low as -20°Celsius. The Chinese capital last saw such similarly extremely cold weather on Jan. 7, 2021, when the temperature dropped to -19.6℃.The cold snap (寒潮) in Beijing this week, compared with the autumn-like conditions a week ago, mirrored the sharp swings in temperatures recently. In October, Beijing experienced one of its warmest Octobers in decades in a year of weather extremes.On Monday, the government warned of road icing in large parts of the city of nearly 22 million, with authorities shutting some expressways or partially closing sections. By 10 a. m. local time, 62 out of a few hundred flights had been cancelled at the Beijing Capital Airport. Railway authorities enforced speed limits on lines connecting Beijing and Guangzhou in southern China, causing delays in some passenger trains. By 7 a. m. Monday, more than 180 bus routes in Beijing had been suspended. The official Beijing Daily reported that vegetable stocks were enough, hitting this year’s hig hest daily market volume of 23,800 tons, as merchants stocked up (备货) ahead of time. Huang, a Beijing resident working in the internet sector, said the snow in Beijing came early. “Normally, it doesn’t snow until the Spring Festival,” Huang said, referring to the start of the Lunar New Year, which typically falls in January or February.4. Which of the following is not used to show the seriousness of the snowfall in paragraph?A．By listing out numbers. B．By illustrating a viewpoint.C．By citing data from the authority. D．By making comparisons.5. What contrast in weather conditions did Beijing experience as mentioned in the article?A．From hot summers to mild winters.B．From dry conditions to heavy rainfall.C．From autumn-like conditions to a sudden coldness.D．From constant snow to unexpectedly warm temperatures.6. Which of the following word is close to the meaning of “enforced” in paragraph 4?A．introduced B．obeyed C．happened D．improved7. What positive measure did merchants in Beijing take in anticipation of the snowfall?A．Organized community support groups. B．Increased storage of essential supplies.C．Created emergency shelters for the homeless. D．Offered discounts and sales to boost business.Fictional, computer-generated human faces are so convincing they can fool even trained observers. They can be easily downloaded online and used for Internet scams(诈骗)and fake social media profiles.Al programs called generative adversarial networks (生成对抗网络), or GANs, can learn to create fake images that are less and less distinguishable from real images, by competing two neural networks against each other.Nightingale and her colleague Hany Farid at the University of California, Berkeley, asked 315 participants, recruited on a crowdsourcing website, to say whether they could distinguish a selection of 400 fake photos from 400 photographs of real people. Each set consisted of 100 people from each of four ethnic groups: white, Black, East Asian and South Asian.This group had an accuracy rate of 48.2 percent—slightly worse than chance. A second group of 219 participants were given training to recognize computer-generated faces. This group had an accuracy rate of 59 percent, but this difference is negligible (可忽略的), says Nightingale.The researchers also asked a separate group of 223 participants to rate a selection of the same faces on their level of trustworthiness, on a scale of 1 to 7. They rated the fake faces as 8 percent more trustworthy, on average, than the real faces—a small yet significant difference, according to Nightingale. That might be because artificial faces look more like “average” human faces, and people are more likely to trust typical-looking faces, she says.Looking at the extremes, the four faces rated most untrustworthy were real, whereas the three most trustworthy faces were fake.“We need stricter ethical guidelines and more legal frameworks in place because, inevitably, there are going to be people out there who want to use these images to do harm, and that’s worrying,” says Nightingale.To reduce these risks, developers could add watermarks to their images to flag them as fake. she says. “In my opinion, this is bad enough. It’s just going to get worse if we don’t do something to stop it.”8. What can we know about GANs?A．GANs can cheat trained observers.B．GANs should be used under strict legal frameworks.C．GANs can generate artificial pictures close to real ones.D．GANs-generated Images can not be distinguished from real ones.9. Why did Nightingale and Farid carry out the research?A．To warn people the risk of online fraud.B．To train people to discover fake photos online.C．To see if people can distinguish fake faces from real ones.D．To test whether GANs can create fake faces to fool people.10. What does Nightingale mean in the last paragraph?A．Stricter laws and regulations should be imposed.B．Effective ways are needed but not found yet.C．Watermarks are an effective way against fake images.D．Responsibility should be taken by developers to prevent misuse of fake images.11. Which of the following is the best title for this passage?A．Development of Internet scams. B．Development of AI technologyC．Will fake faces look more trustworthy? D．Legal frameworks for GANsObese people experience discrimination (歧视) in many parts of their lives, and the workplace is no exception. Studies have long shown that obese workers, defined as those with a body-mass index (BMI) of 30 or more, earn significantly less than their slimmer co-workers.Yet the costs of we ight discrimination may be even greater than previously thought. “The overwhelming evidence,” wrote the Institute for employment Studies, “is that it is only women living with obesity who experience the obesity wage penalty (薪资损失).” They were expressing a view that is widely aired in academic papers. To test it, The Economist has analyzed data concerning 23,000 workers from the American Time Use Survey, conducted by the Bureau of Labour Statistics. Our number-processing suggests that, in fact, being obese hurts the earnings of both women and men.The data we analyzed cover men and women aged between 25 and 54 and in full-time employment. At a general level, it is true that men’s BMIs are unrelated to their wages. But that changes for men with university degrees. For them, obesity is associated with a wage penalty of nearly 8%, even after accounting for the separate effects of age, race, graduate education and marital status.The conclusion — that well-educated workers in particular are penalized for their weight — holds for both sexes. Moreover, the higher your level of education, the greater the penalty. We found that obese men with a Bachelor’s degree (学士学位) earn 5% less than their thinner colleagues, while those with a Master’s degree earn 14% less. Obese women, it is true, still have it worse: for them, the equivalent figures are 12% and 19%, respectively (分别地).Your line of work makes a difference, too. When we dealt with the numbers for individual occupations and industries, we found the greatest differences in high-skilled jobs. Obese workers in health care, for example, make 11% less than their slimmer colleagues; those in management roles make roughly 9% less, on average. In sectors such as construction and agriculture, meanwhile, obesity is actually associated with higher wages.These results suggest that the total costs of wage discrimination borne by overweight workers in America are greater than expected. Now, it’s time for our governments to take it seriously.12. What does the underlined word “it” refer to in paragraph 2?A．Obese men earn less salary.B．Only obese women earn less salary.C．Both obese men and women earn less salary.D．Weight discrimination may be greater than previously thought.13. Who may experience more discrimination compared to their colleagues according to the data?A．A fat woman office director.B．An obese construction worker.C．An obese man with a bachelor’s degree.D．A heavier female doctor with a Doctor’s degree.14. What is the writer’s attitude of overweight discrimination?A．Supportive B．Objective C．Subjective D．indifferent 15. What might the author continue talking about?A．Overweight discrimination in other countries.B．The reason of discriminating obese people in their lives.C．American people’s attitude towards overweight discrimination.D．Actions taken against overweight discrimination in workplaces.Emotional energy is a relatively new term to describe our vitality (活力). 16 If we feel that some situations drain (耗尽) us, then it’s because they take away all our vitality in matters that are insignificant, but ones that do require effort. They’re situations that only distract us from what’ s truly important, and from the things that enrich us. Let’s learn to identify them and avoid th em.Arguments about insignificant issuesA debate is a great opportunity to present your own points of view and learn from other’s opinions. However, something very different happens when two people get into a pointless argument. 17 Gossip18 This sort of curiosity is no more than a sign of a lack of identity. Whoever gossips about others looks for themselves in other people. The thing is, they just can’t find themselves.Worrying over and over againOne of the situations that drain our emotional energy is unstoppable doubt. This is when we think and think but only come up with “ifs” and “buts”. We try to find the right answer or make the right decision just by reflection. 19Need for approvalWe’re constantly trying to get other people’s approval. 20 Instead of investing time to explore who we are, whether others like us or not, we just spend our time doing things that other people want us to do. Generally, people either accept you or they don’t, and sometimes for reasons that are completely beyond your control.My fiancé (未婚夫) and I were excited about shopping for our first home. But our funds were_______, and none of the houses in our price range seemed satisfactory.One agent recommended a house in particular. Although her description sounded wonderful, the price was _______ our range, so we declined. But she kept urging us to have a look _______.We finally did and it was _______ at first sight. It was Our Home, small and charming, overlooking a quiet lake. Walking through the rooms and talking with the owners, a nice elderly couple, we felt the warmth and _______ of the marriage within that home. As perfect as it was, the price remained too high for us. But every day, we would sit by the lake, looking at the house and dreaming of what it would be like to live there.Days later, we made a(n) _______ far below the asking price. Surprisingly, they didn’t _______ us. They renewed their offer instead. It was also much more than we could afford, but far _______ than the original asking price.The next day, we got a _______ message that another buyer had offered a much higher price. Even so, we decided to talk with the ________ directly. We made our final offer, which ________ was thousands of do llars less than the other buyer’s bid. We knew it, ________ we had to try.“Sold!” said the owner. Then he explained: He’d seen us sitting by the lake all those times; he knew how much we loved the place and that we’d ________ the years of work they had p ut into their home; he realized he would take a loss by selling it to us, but it was worthwhile; we were the people they wanted to live there. He told us to consider the ________ in the price “an early wedding present”.That’s how we found our home and how I learned that when people are ________, they are not strangers, only friends we haven’t yet met.21.A．needed B．limited C．enough D．large22.A．below B．within C．beyond D．between 23.A．at least B．at most C．at times D．at hand 24.A．relief B．concern C．love D．curiosity 25.A．pride B．happiness C．challenge D．desire 26.A．effort B．offer C．promise D．profit27.A．come across B．look after C．depend on D．laugh at 28.A．worse B．better C．less D．higher 29.A．relaxing B．disappointing C．pleasant D．regular 30.A．agents B．buyers C．managers D．owners 31.A．already B．still C．generally D．ever32.A．so B．or C．for D．but33.A．check B．analyze C．appreciate D．ignore 34.A．increase B．difference C．interest D．average35.A．kind B．polite C．smart D．energetic阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

Non verbal communication 非语

The relation between verbal and nonverbal communication
• The relative importance of verbal and nonverbal communication was investigated by Albert Mehrabian and reported in two papers that concluded: "It is suggested that the combined effect of simultaneous verbal, vocal, and facial attitude communications is a weighted sum of their independent effects - with coefficients of .07, .38, and .55, respectively." • This "rule" that clues from spoken words, from the voice tone, and from the facial expression, contribute 7 %, 38 %, and 55 % respectively to the total meaning, is widely cited. • Since then, other studies have tion of verbal and nonverbal signals under more naturalistic situations. Argyle found that non-verbal cues had 4.3 times the effect of verbal cues. • The most important effect was that body posture communicated superior status in a very efficient way.

2025年研究生考试考研英语(一201)试卷及答案指导

2025年研究生考试考研英语(一201)自测试卷及答案指导一、完型填空（10分）Section I: Cloze TestDirections: Read the following text carefully and choose the best answer from the four choices marked A, B, C, and D for each blank.Passage:In today’s rapidly evolving digital landscape, the role of social media has become increasingly significant. Social media platforms are not just tools for personal interaction; they also serve as powerful channels for business promotion and customer engagement. Companies are now leveraging these platforms to reach out to their target audience more effectively than ever before. However, the effectiveness of social media marketing (1)_on how well the company understands its audience and the specific platform being used. For instance, while Facebook may be suitable for reaching older demographics, Instagram is more popular among younger users. Therefore, it is crucial for businesses to tailor their content to fit the preferences and behaviors of the (2)_demographic they wish to target.Moreover, the rise of mobile devices has further transformed the way peopleconsume content online. The majority of social media users now access these platforms via smartphones, which means that companies must ensure that their content is optimized for mobile viewing. In addition, the speed at which information spreads on social media can be both a boon and a bane. On one hand, positive news about a brand can quickly go viral, leading to increased visibility and potentially higher sales. On the other hand, negative publicity can spread just as fast, potentially causing serious damage to a brand’s reputation. As such, it is imperative for companies to have a well-thought-out strategy for managing their online presence and responding to feedback in a timely and professional manner.In conclusion, social media offers unparalleled opportunities for businesses to connect with customers, but it requires careful planning and execution to (3)___the maximum benefits. By staying attuned to trends and continuously adapting their strategies, companies can harness the power of social media to foster growth and build strong relationships with their audiences.1.[A] relies [B] bases [C] stands [D] depends2.[A] particular [B] peculiar [C] special [D] unique3.[A] obtain [B] gain [C] achieve [D] accomplishAnswers:1.D - depends2.A - particular3.C - achieveThis cloze test is designed to assess comprehension and vocabulary skills, as well as the ability to infer the correct usage of words within the context of the passage. Each question is crafted to require understanding of the sentence structure and meaning to select the best option.二、传统阅读理解（本部分有4大题，每大题10分，共40分）第一题Passage:In the 1950s, the United States experienced a significant shift in the way people viewed education. This shift was largely due to the Cold War, which created a demand for a highly educated workforce. As a result, the number of students pursuing higher education in the U.S. began to grow rapidly.One of the most important developments during this period was the creation of the Master’s degree program. The Master’s degree was designed to provide students with advanced knowledge and skills in a specific field. This program became increasingly popular as more and more people realized the value of a higher education.The growth of the Master’s degree program had a profound impact on American society. It helped to create a more educated and skilled workforce, which in turn contributed to the nation’s economic growth. It also helped to improve the quality of life for many Americans by providing them with opportunities for career advancement and personal development.Today, the Master’s degree is still an important part of the American educational system. However, there are some challenges that need to be addressed. One of the biggest challenges is the rising cost of education. As the cost of tuition continues to rise, many students are unable to afford the cost of a Master’s degree. This is a problem that needs to be addressed if we are to continue to provide high-quality education to all Americans.1、What was the main reason for the shift in the way people viewed education in the 1950s?A. The demand for a highly educated workforce due to the Cold War.B. The desire to improve the quality of life for all Americans.C. The increasing cost of education.D. The creation of the Master’s degree program.2、What is the purpose of the Master’s degree program?A. To provide students with basic knowledge and skills in a specific field.B. To provide students with advanced knowledge and skills in a specific field.C. To provide students with job training.D. To provide students with a general education.3、How did the growth of the Master’s degree program impact American society?A. It helped to create a more educated and skilled workforce.B. It helped to improve the quality of life for many Americans.C. It caused the economy to decline.D. It increased the cost of education.4、What is one of the biggest challenges facing the Master’s deg ree program today?A. The demand for a highly educated workforce.B. The rising cost of education.C. The desire to improve the quality of life for all Americans.D. The creation of new educational programs.5、What is the author’s main point in the last pa ragraph?A. The Master’s degree program is still an important part of the American educational system.B. The cost of education needs to be addressed.C. The Master’s degree program is no longer relevant.D. The author is unsure about the future of the Master’s degree program.第二题Reading Comprehension (Traditional)Passage:The digital revolution has transformed the way we live, work, and communicate. With the advent of the internet and the proliferation of smart devices, information is more accessible than ever before. This transformation has had a profound impact on education, with online learning platforms providing unprecedented access to knowledge. However, this shift towards digital learningalso poses challenges, particularly in terms of ensuring equitable access and maintaining educational quality.While the benefits of digital learning are numerous, including flexibility, cost-effectiveness, and the ability to reach a wider audience, there are concerns about the potential for increased social isolation and the difficulty in replicating the dynamic, interactive environment of a traditional classroom. Moreover, not all students have equal access to the technology required for online learning, which can exacerbate existing inequalities. It’s crucial that as we embrace the opportunities presented by digital technologies, we also address these challenges to ensure that no student is left behind.Educators must adapt their teaching methods to take advantage of new tools while also being mindful of the need to foster a sense of community and support among students. By integrating both digital and traditional approaches, it’s possible to create a learning environment that leverages the strengths of each, ultimately enhancing the educational experience for all students.Questions:1、What is one of the main impacts of the digital revolution mentioned in the passage?•A) The reduction of social interactions•B) The increase in physical book sales•C) The transformation of communication methods•D) The decline of online learning platformsAnswer: C) The transformation of communication methods2、According to the passage, what is a challenge associated with digital learning?•A) The inability to provide any form of interaction•B) The potential to widen the gap between different socioeconomic groups •C) The lack of available content for online courses•D) The complete replacement of traditional classroomsAnswer: B) The potential to widen the gap between different socioeconomic groups3、Which of the following is NOT listed as a benefit of digital learning in the passage?•A) Cost-effectiveness•B) Flexibility•C) Increased social isolation•D) Wider reachAnswer: C) Increased social isolation4、The passage suggests that educators should do which of the following in response to the digital revolution?•A) Abandon all traditional teaching methods•B) Focus solely on improving students’ technical skills•C) Integrate digital and traditional teaching methods•D) Avoid using any digital tools in the classroomAnswer: C) Integrate digital and traditional teaching methods5、What is the author’s stance on the role of digital technologies ineducation?•A) They are unnecessary and should be avoided•B) They offer opportunities that should be embraced, but with caution •C) They are the only solution to current educational challenges•D) They have no real impact on the quality of educationAnswer: B) They offer opportunities that should be embraced, but with cautionThis reading comprehension exercise is designed to test your understanding of the text and your ability to identify key points and arguments within the passage.第三题Reading PassageWhen the French sociologist and philosopher Henri Lefebvre died in 1991, he left behind a body of work that has had a profound influence on the fields of sociology, philosophy, and cultural studies. Lefebvre’s theories focused on the relationship between space and society, particularly how space is produced, represented, and experienced. His work has been widely discussed and debated, with scholars and critics alike finding value in his insights.Lefebvre’s most famous work, “The Production of Space,” published in 1974, laid the foundation for his theoretical framework. In this book, he argues that space is not simply a container for human activities but rather an active agent in shaping social relationships and structures. Lefebvre introduces the concept of “three spaces” to describe the production of space: the perceived space,the lived space, and the representative space.1、According to Lefebvre, what is the primary focus of his theories?A. The development of urban planningB. The relationship between space and societyC. The history of architectural designD. The evolution of cultural practices2、What is the main argument presented in “The Production of Space”?A. Space is a passive entity that reflects social structures.B. Space is a fundamental building block of society.C. Space is an object that can be easily manipulated by humans.D. Space is irrelevant to the functioning of society.3、Lefebvre identifies three distinct spaces. Which of the following is NOT one of these spaces?A. Perceived spaceB. Lived spaceC. Representative spaceD. Economic space4、How does Lefebvre define the concept of “three spaces”?A. They are different types of architectural designs.B. They represent different stages of the production of space.C. They are different ways of perceiving and experiencing space.D. They are different social classes that occupy space.5、What is the significance of Lefebvre’s work in the fields of sociology and philosophy?A. It provides a new perspective on the role of space in social relationships.B. It offers a comprehensive guide to urban planning and development.C. It promotes the idea that space is an unimportant aspect of society.D. It focuses solely on the history of architectural movements.Answers:1、B2、B3、D4、C5、A第四题Reading Comprehension (Traditional)Read the following passage and answer the questions that follow. Choose the best answer from the options provided.Passage:In recent years, there has been a growing interest in the concept of “smart cities,” which are urban areas that u se different types of electronic data collection sensors to supply information which is used to manage assets and resources efficiently. This includes data collected from citizens, devices, andassets that is processed and analyzed to monitor and manage traffic and transportation systems, power plants, water supply networks, waste management, law enforcement, information systems, schools, libraries, hospitals, and other community services. The goal of building a smart city is to improve quality of life by using technology to enhance the performance and interactivity of urban services, to reduce costs and resource consumption, and to increase contact between citizens and government. Smart city applications are developed to address urban challenges such as environmental sustainability, mobility, and economic development.Critics argue, however, that while the idea of a smart city is appealing, it raises significant concerns about privacy and security. As more and more aspects of daily life become digitized, the amount of personal data being collected also increases, leading to potential misuse or unauthorized access. Moreover, the reliance on technology for critical infrastructure can create vulnerabilities if not properly secured against cyber-attacks. There is also a risk of widening the digital divide, as those without access to the necessary technologies may be left behind, further exacerbating social inequalities.Despite these concerns, many governments around the world are moving forward with plans to develop smart cities, seeing them as a key component of their future strategies. They believe that the benefits of improved efficiency and service delivery will outweigh the potential risks, provided that adequate safeguards are put in place to protect citizen s’ data and ensure the resilience of thecity’s technological framework.Questions:1、What is the primary purpose of developing a smart city?•A) To collect as much data as possible•B) To improve the quality of life through efficient use of technology •C) To replace all traditional forms of communication•D) To eliminate the need for human interaction in urban services2、According to the passage, what is one of the main concerns raised by critics regarding smart cities?•A) The lack of available technology•B) The high cost of implementing smart city solutions•C) Privacy and security issues related to data collection•D) The inability to provide essential services3、Which of the following is NOT mentioned as an area where smart city technology could be applied?•A) Traffic and transportation systems•B) Waste management•C) Educational institutions•D) Agricultural production4、How do some governments view the development of smart cities despite the criticisms?•A) As a risky endeavor that should be avoided•B) As a temporary trend that will soon pass•C) As a strategic move with long-term benefits•D) As an unnecessary investment in technology5、What does the term “digital divide” refer to in the context of smart cities?•A) The gap between the amount of data collected and the amount of data analyzed•B) The difference in technological advancement between urban and rural areas•C) The disparity in access to technology and its impact on social inequality•D) The separation of digital and non-digital methods of service delivery Answers:1、B) To improve the quality of life through efficient use of technology2、C) Privacy and security issues related to data collection3、D) Agricultural production4、C) As a strategic move with long-term benefits5、C) The disparity in access to technology and its impact on social inequality三、阅读理解新题型（10分）Reading Comprehension (New Type)Passage:The rise of e-commerce has transformed the way people shop and has had aprofound impact on traditional brick-and-mortar retailers. Online shopping offers convenience, a wide range of products, and competitive prices. However, it has also raised concerns about the future of physical stores. This passage examines the challenges and opportunities facing traditional retailers in the age of e-commerce.In recent years, the popularity of e-commerce has soared, thanks to advancements in technology and changing consumer behavior. According to a report by Statista, global e-commerce sales reached nearly$4.2 trillion in 2020. This upward trend is expected to continue, with projections showing that online sales will account for 25% of total retail sales by 2025. As a result, traditional retailers are facing fierce competition and must adapt to the digital landscape.One of the main challenges for brick-and-mortar retailers is the shift in consumer preferences. Many shoppers now prefer the convenience of online shopping, which allows them to compare prices, read reviews, and purchase products from the comfort of their homes. This has led to a decrease in foot traffic in physical stores, causing many retailers to struggle to attract customers. Additionally, the ability to offer a wide range of products at competitive prices has become a hallmark of e-commerce, making it difficult for traditional retailers to compete.Despite these challenges, there are opportunities for traditional retailers to thrive in the age of e-commerce. One approach is to leverage the unique strengths of physical stores, such as the ability to provide an immersiveshopping experience and personalized customer service. Retailers can also use technology to enhance the in-store experience, such as implementing augmented reality (AR) to allow customers to visualize products in their own homes before purchasing.Another strategy is to embrace the digital world and create a seamless shopping experience that integrates online and offline channels. For example, retailers can offer online returns to brick-and-mortar stores, allowing customers to shop online and return items in person. This not only provides convenience but also encourages customers to make additional purchases while they are in the store.Furthermore, traditional retailers can leverage their established brand loyalty and customer base to create a competitive advantage. By focusing on niche markets and offering unique products or services, retailers can differentiate themselves from e-commerce giants. Additionally, retailers can invest in marketing and promotions to drive traffic to their physical stores, even as more consumers turn to online shopping.In conclusion, the rise of e-commerce has presented traditional retailers with significant challenges. However, by embracing the digital landscape, leveraging their unique strengths, and focusing on customer satisfaction, traditional retailers can adapt and thrive in the age of e-commerce.Questions:1.What is the main concern raised about traditional retailers in the age of e-commerce?2.According to the passage, what is one of the main reasons for the decline in foot traffic in physical stores?3.How can traditional retailers leverage technology to enhance the in-store experience?4.What strategy is mentioned in the passage that involves integrating online and offline channels?5.How can traditional retailers create a competitive advantage in the age of e-commerce?Answers:1.The main concern is the fierce competition from e-commerce and the shift in consumer preferences towards online shopping.2.The main reason is the convenience and competitive prices offered by e-commerce, which make it difficult for traditional retailers to compete.3.Traditional retailers can leverage technology by implementing augmented reality (AR) and offering online returns to brick-and-mortar stores.4.The strategy mentioned is to create a seamless shopping experience that integrates online and offline channels, such as offering online returns to brick-and-mortar stores.5.Traditional retailers can create a competitive advantage by focusing on niche markets, offering unique products or services, and investing in marketing and promotions to drive traffic to their physical stores.四、翻译（本大题有5小题，每小题2分，共10分）First QuestionTranslate the following sentence into Chinese. Write your translation on the ANSWER SHEET.Original Sentence:“Although technology has brought about nume rous conveniences in our daily lives, it is also true that it has led to significant privacy concerns, especially with the rapid development of digital communication tools.”Answer:尽管技术在我们的日常生活中带来了诸多便利，但也不可否认它导致了重大的隐私问题，尤其是在数字通信工具快速发展的情况下。

A dynamical system with a strange attractor and invariant tori.

Physics Letters A 378(2014)1361–1363Contents lists available at ScienceDirectPhysics Letters A/locate/plaA dynamical system with a strange attractor and invariant toriJ.C.SprottDepartment of Physics,University of Wisconsin-Madison,Madison,WI 53706,USAa r t i c l e i n f o ab s t r ac tArticle history:Received 15January 2014Received in revised form 13March 2014Accepted 17March 2014Available online 21March 2014Communicated by C.R.Doering Keywords:Dynamical system Strange attractor Invariant torusThis paper describes a simple three-dimensional time-reversible system of ODEs with quadratic nonlinearities and the unusual property that it is exhibits conservative behavior for some initial conditions and dissipative behavior for others.The conservative regime has quasi-periodic orbits whose amplitude depend on the initial conditions,while the dissipative regime is chaotic.Thus a strange attractor coexists with an inﬁnite set of nested invariant tori in the state space.©2014Elsevier B.V.All rights reserved.1.IntroductionContinuous-time dynamical systems governed by a set of ﬁrst-order ordinary differential equations are usually categorized as be-ing either conservative or dissipative.Conservative systems main-tain the state space volume when time-averaged along the tra-jectory and are usually characterized by some conserved quantity such as a Hamiltonian function.Depending on the initial condi-tions,they typically have orbits that are quasi-periodic and lie on surfaces of nested tori surrounded by a chaotic sea whose dimen-sion is equal to the dimension of the state space.Dissipative systems have a state space volume that decreases on average along the trajectory so that the orbit approaches an at-tractor of measure zero in the state space.If the dissipative system is chaotic,the attractor is strange with a non-integer dimension and fractal structure.Furthermore,it is possible for the same dissi-pative system to have coexisting stable equilibria,limit cycles,and strange attractors each with its own dimension and basin of at-traction [1,2].However,if the dissipation is nonlinear and thus dependent on the position in state space,systems can be dissipative for some ini-tial conditions,while other initial conditions lead to solutions for which the dissipation averages exactly to zero along the orbit [3].The next section describes a simple example of such a system in which a strange attractor with chaotic orbits coexists with an inﬁ-nite set of nested invariant tori containing quasi-periodic orbits.E-mail address:sprott@ .URL: .2.ExampleIn a numerical search for chaotic systems that have no equilib-rium points and only bounded orbits for all initial conditions,the following unusual system was discovered:˙x=y +2xy +xz ˙y=1−2x 2+yz ˙z=x −x 2−y 2(1)The numerical evidence of boundedness is that the ﬂow vec-tor is everywhere inward on a sphere of radius R centered on the point (1,0,−1)except for small holes at (0,0,±R )that occupy a vanishingly small fraction of the sphere as R →∞.Furthermore,orbits with initial conditions within these holes loop back to the interior of the sphere for R suﬃciently large.Since the system is bounded with no equilibrium points (stable or unstable),the only possible solutions are (quasi)-periodic or chaotic.Because the system is invariant under the transformation (x ,y ,z ,t )→(x ,−y ,−z ,−t ),two types of solutions can occur.The ﬁrst type is symmetric under a 180◦rotation about the x -axis and is time-reversal invariant.Thus it exhibits conservative behav-ior.The second type has an attractor in forward time and another attractor in reversed time that are symmetric with one another through a 180◦rotation about the x -axis.This reversed time at-tractor is a repellor in forward time.Since the same points in state space cannot be both an attractor and a repellor,any symmet-ric solutions necessarily conserve state space volume on average (non-attracting).In fact,it turns out that the system displays both behaviors depending on the initial conditions./10.1016/j.physleta.2014.03.0280375-9601/©2014Elsevier B.V.All rights reserved.1362J.C.Sprott/Physics Letters A378(2014)1361–1363Fig.1.A strange attractor(red)interlinked with a coexisting invariant torus(green) for System(1).(For interpretation of the references to color in thisﬁgure legend, the reader is referred to the web version of this article.)The dissipation is given by the trace of the Jacobian matrix, Tr(J)=2(y+z)whose value depends on y and z and thus should be time-averaged along the orbit,and whose average value is the sum of the Lyapunov exponents.The surprise was that the time average of y+z is negative for some initial conditions such as (x0,y0,z0)=(2,0,0)and zero for others such as(1,0,0).The boundedness of the system ensures that y+z cannot be positive, and the absence of equilibrium points ensures that all orbits are time-dependent.Theﬁrst initial condition gives a strange attrac-tor with Lyapunov exponents(0.0540,0,−0.1575)and a Kaplan–Yorke dimension of2.3429,and the second initial condition gives a torus with Lyapunov exponents(0,0,0)and a dimension of2.0.The strange attractor is strongly multifractal with a capacity di-mension of about2.92and a correlation dimension of about1.49. Since there are no equilibrium points,the strange attractor is“hid-den”in the sense described by Leonov and Kuznetsov[4,5],mean-ing that its basin does not intersect with small neighborhoods of any equilibrium points,and thus it cannot be found by standard computational methods.However,because the system is bounded, any initial condition suﬃciently far from the origin will go to the attractor(R=5is suﬃcient).The two solutions are shown in Fig.1projected onto the xy-plane.The strange attractor and torus are interlinked,with the attractor resembling the“cord”attractor described by Letellier and Aguirre[6].A different projection edge-on to the torus and also showing the intertwined repellor is in Fig.2.The attractor and re-pellor are tightly twisted like the strands of a rope where they pass through the hole in the torus.The repellor is identiﬁed by simply reversing the sign of time in the equations and showing a portion of the resulting orbit after discarding the initial transient.Addi-tional conﬁrmation that the torus is non-attracting comes from a very long calculation(to a time of t=1×1010)using a fourth-order Runge–Kutta integrator with adaptive step size,which gives an upper bound of| y+z |<1×10−10.Like all strange attractors,this one is dense in unstable periodic orbits.The orbit with the shortest period lies close to the surface of the outermost torus and makesﬁve loops projected onto the xy-plane while linking the torus once.It has a period of approxi-mately12.58,a net dissipation of2 y+z −0.0121,and can be observed by using the initial conditions(0.5002,0.0023,−0.0791).Fig.3shows a cross section of theﬂow in the z=0plane for80 initial conditions uniformly distributed over the range−2<x0<3Fig.2.A different view of the strange attractor(red)intertwined with a symmetric repellor(black)and both interlinked with a coexisting invariant torus(green)for System(1).(For interpretation of the references to color in thisﬁgure legend,the reader is referred to the web version of thisarticle.)Fig.3.Cross section in the z=0plane showing nested invariant tori surrounded by a multifractal strange attractor for System(1).Initial conditions in the conservative region are shown in blue,and initial conditions in the basin of attraction of the strange attractor are shown in yellow.(For interpretation of the references to color in thisﬁgure legend,the reader is referred to the web version of this article.)with y0=z0=0.This plot is called a“cross section”rather than a“Poincarésection”because the crossings of the z=0plane are plotted in both directions rather than a single direction.The nested invariant tori are surrounded by a strange attractor.The basin boundary of the strange attractor appears to be coincident with the outermost toroidal surface,and its basin extends to inﬁnity in all directions.The background colors in theﬁgure show the regions of conservative and dissipative behavior,respectively.The boundary between the conservative and dissipative region in the z=0plane is near a circle given by(x−1/√2)2+y2=1,a result that begs for an explanation.Initial conditions near that boundary such as(0,0.707,0)or near one of the separatrices within the toroidal region such as(0.4999,0.01,0)can appear to be conservative and chaotic,but either the largest Lyapunov expo-nent eventually converges to zero or the orbit eventually reachesJ.C.Sprott/Physics Letters A378(2014)1361–13631363the strongly dissipative strange attractor.There is no convincing evidence for a conservative chaotic sea.3.ConclusionsThis paper describes an unusual example of a chaotic dynamical system that exhibits conservative behavior for some initial condi-tions and dissipative behavior for others so that an inﬁnite set of nested invariant tori coexist with and are linked by a strange at-tractor.For initial conditions suﬃciently close to the origin,the quasi-periodic orbits are such that the time average of y+z is identically zero to within numerical precision,while orbits start-ing farther from the origin have a strongly negative value of that quantity with a sharp,nearly circular toroidal boundary separating the two regions.It would be good to have a better understanding of this phenomenon,a theory for when it will occur,a prediction for the location of the boundary,and details of the bifurcations that occur in theﬁve-dimensional parameter space,but those chal-lenges will be left for the future.Shortly after discovering this system,another similar example was found in a nonlinearly dissipative Nosé–Hoover oscillator with a hyperbolic tangent nonlinearity and four equilibrium points[7]. In that case,an attracting limit cycle coexists with two sets of in-variant tori for some values of the parameters,while a space-ﬁlling multifractal strange attractor with a Kaplan–Yorke dimension of 2.945coexists with the tori for other values of the parameters. This result suggests that the behavior described here may be com-mon in time-reversible dynamical systems with nonlinear damping but apparently not widely known or appreciated.AcknowledgementsI am grateful to Zeraoulia Elhadj for suggesting the search that uncovered this example and to Bill Hoover for extensive discus-sions.References[1]J.C.Sprott,X.Wang,G.Chen,Int.J.Bifurc.Chaos Appl.Sci.Eng.23(2013)1350093.[2]C.Li,J.C.Sprott,Int.J.Bifurc.Chaos Appl.Sci.Eng.23(2013)1350199.[3]A.Politi,G.L.Oppo,R.Badii,Phys.Rev.A(1986)4055.[4]G.A.Leonov,N.V.Kuznetsov,V.I.Vagaitsev,Phys.Lett.A375(2011)2230.[5]G.A.Leonov,N.V.Kuznetsov,Int.J.Bifurc.Chaos Appl.Sci.Eng.23(2013)12330002.[6]C.Letellier,L.A.Aguirre,Phys.Rev.E85(2012)036204.[7]J.C.Sprott,W.G.Hoover,C.G.Hoover,arXiv:1401.1762[cond-mat.stat-mech].。

与朋友们交谈的英语作文

When engaging in conversations with friends,there are several key elements to consider to ensure the interaction is enjoyable and meaningful.Here are some points to keep in mind when writing an English composition about conversing with friends:1.Choosing the Right Topic:Start by selecting a topic that is interesting and relevant to all participants.This could be a shared experience,a current event,or a common interest.2.Active Listening:Emphasize the importance of active listening in a conversation.This means not only hearing what is being said but also understanding and responding thoughtfully.3.Respecting Different Opinions:Highlight the value of respecting differing viewpoints. Friends may not always agree,but its crucial to maintain a respectful dialogue.ing Appropriate Language:The language used in conversations should be appropriate for the setting and the people involved.Slang and colloquialisms may be suitable among close friends but might not be appropriate in more formal settings.5.Sharing Personal Anecdotes:Personal stories can add depth to a conversation and help to build connections.Sharing experiences can lead to empathy and understanding among friends.6.Asking OpenEnded Questions:Encourage the use of openended questions to promote deeper discussions.These types of questions cannot be answered with a simple yes or no and invite more elaborate responses.7.Being Supportive and Empathetic:Show support and empathy when friends are sharing their feelings or concerns.This can strengthen the bond between friends and create a safe space for open communication.ing Humor Appropriately:Humor can lighten the mood and make conversations more enjoyable.However,its important to use humor that is inclusive and considerate of everyones feelings.9.Being Aware of NonVerbal Cues:Nonverbal communication,such as body language and facial expressions,plays a significant role in conversations.Being aware of these cues can help in understanding the unspoken aspects of a discussion.10.Ending the Conversation Gracefully:Know when its time to wrap up the conversation. Ending on a positive note can leave a lasting impression and set the stage for futureinteractions.11.Reflecting on the Conversation:After the conversation,it can be beneficial to reflect on what was discussed,what was learned,and how the interaction can be improved in the future.12.Cultural Sensitivity:In a diverse group of friends,its important to be aware of cultural differences that may affect communication styles and topics of conversation.By incorporating these elements into your English composition,you can create a comprehensive and insightful piece on the art of conversing with friends.Remember to use descriptive language and provide specific examples to make your writing more engaging and relatable.。

大学垃圾分类英语作文

大学垃圾分类英语作文Waste sorting has become an increasingly important issue in our society and universities are no exception. In this essay I will discuss the importance of waste sorting in universities and suggest some practical measures to promote it.Firstly waste sorting is crucial for environmental protection. By separating recyclable materials from nonrecyclable ones we can reduce the amount of waste that ends up in landfills which helps to conserve natural resources and prevent pollution. Universities as educational institutions should take the lead in promoting environmental awareness and sustainable practices.To encourage waste sorting on campus universities can implement the following measures1. Education and Awareness Organize seminars and workshops to educate students about the benefits of waste sorting and how to do it properly. This can be done through interactive sessions where students can learn about different types of waste and their respective disposal methods.2. Infrastructure Development Install waste sorting bins in strategic locations across the campus. These bins should be clearly labeled to indicate which type of waste they are meant for such as paper plastic organic waste and hazardous waste.3. Incentive Programs Introduce incentive programs to motivate students and staff to sort their waste. This could include rewards for those who consistently sort their waste or penalties for those who do not.4. Regular Audits Conduct regular audits of waste sorting practices to ensure compliance and identify areas for improvement. Feedback from these audits can be used to refine waste sorting policies and procedures.5. Collaboration with Local Authorities Work closely with local waste management authorities to ensure that sorted waste is properly collected and processed. This collaboration can also help in setting up recycling programs and facilities on campus.6. Integration into Curriculum Incorporate waste sorting and environmental stewardship into the academic curriculum. This can help students understand the importance of wastemanagement from a scientific and practical perspective.7. Use of Technology Utilize apps or digital platforms to track waste sorting activities and provide realtime feedback to the community. This can make the process more engaging and transparent.8. Community Involvement Encourage student organizations and clubs to take part in waste sorting initiatives. This can foster a sense of community responsibility and peertopeer learning.In conclusion waste sorting in universities is not just about following regulations it is about cultivating a culture of sustainability and environmental responsibility. By implementing these measures universities can play a significant role in shaping the attitudes and behaviors of future generations towards waste management.。

TPO听力27-30

TPO-27Conversation 11. Why does the woman go to the information desk?●She does not know where the library computers are located.●She does not know how to use a computer to locate the information she needs.●She does not have time to wait until a library computer becomes available.●The book she is looking for was missing from the library shelf.2. Why does the man assume that the woman is in Professor Simpson’s class?●The man recently saw the woman talking with Professor Simpson.●The woman mentioned Profe ssor Simpson’s name.●The woman is carrying the textbook used in Professor Simpson’s class.●The woman is researching a subject that Professor Simpson specialized in.3. What can be inferred about the geology course the woman is taking?●It has led the woman to choose geology as her major course of study.●It is difficult to follow without a background in chemistry and physics.●The woman thinks it is easier than other science courses.●The woman thinks the course is boring.4. What topic does the woman need information on?●The recent activity of a volcano in New Zealand●Various types of volcanoes found in New Zealand●All volcanoes in New Zealand that are still active●How people in New Zealand have prepared for volcanic eruptions5. What does the man imply about the article when he says this:●It may not contain enough background material.●It is part of a series of articles.●It might be too old to be useful.●It is the most recent article published on the subject.Lecture 16. What is the lecture mainly about?●The transplantation of young coral to new reef sites●Efforts to improve the chances of survival of coral reefs●The effects of water temperature change on coral reefs●Confirming the reasons behind the decline of coral reefs7. According to the professor, how might researchers predict the onset of coral bleaching in the future?●By monitoring populations of coral predators●By monitoring bleach-resistant coral species●By monitoring sea surface temperatures●By monitoring degraded reefs that have recovered8. Wh at is the professor’s opinion about coral transplantation?●It is cost-effective.●It is a long-term solution.●It is producing encouraging results.●It does not solve the underlying problems.9. Why does the professor discuss refugia? [Choose two answers]●To explain that the location of coral within a reef affects the coral’s ability to survive●To point out why some coral species are more susceptible to bleaching than others●To suggest that bleaching is not as detrimental to coral health as first thought●To illustrate the importance of studying coral that has a low vulnerability to bleaching10. What does the professor imply about the impact of mangrove forests on coral-reef ecosystems?●Mangrove forests provide habitat for wildlife that feed on coral predators.●Mangrove forests improve the water quality of nearby reefs.●Mangrove forests can produce sediments that pollute coral habitats.●Mangrove forests compete with nearby coral reefs for certain nutrients.11. According to the professor, what effect do lobsters and sea urchins have on a coral reef?●They protect a reef by feeding on destructive organisms.●They hard a reef by taking away important nutrients.●They filter pollutants from water around a reef.●They prevent a reef from growing by preying on young corals.Lecture 212. What does the professor mainly discuss?●Some special techniques used by the makers of vintage Cremonese violins●How the acoustical quality of the violin was improved over time●Factors that may be responsible for the beautiful tone of Cremonese violins●Some criteria that professional violinists use when selecting their instruments13. What does the professor imply about the best modern violin makers?●They are unable to recreate the high quality varnish used by Cremonese violin makers.●Their craftsmanship is comparable to that of the Cremonese violin makers.●They use wood from the same trees that were used to make the Cremonese violins.●Many of them also compose music for the violin.14. Why does the professor discuss the growth cycle of trees?●To clarify how modern violin makers select wood●To highlight a similarity between vintage and modern violins●To explain why tropical wood cannot be used to make violins●To explain what causes variations in density in a piece of wood15. What factor accounts for the particular density differential of the wood used in the Cremonese violins?●The trees that produced the wood were harvested in the spring●The trees that produced the wood grew in an unusually cool climate●The wood was allowed to partially decay before being made into violins●.The wood was coated with a local varnish before it was crafted into violins16. The professor describes and experiment in which wood was exposed to a fungus before being made into a violin. What point does the professor make about the fungus?●It decomposes only certain parts of the wood.●It is found only in the forests of northern Italy.●It was recently discovered in a vintage Cremonese violin.●It decomposes only certain species of trees.17. Why does the professor say this:●To find out how much exposure students have had to live classical music●To use student experiences to support his point about audience members●To indicate that instruments are harder to master than audience members realize●To make a point about the beauty of violin musicConversation 21. Why has the student come to see the professor?●To find out her reaction to a paper he recently submitted●To point out a factual error in an article the class was assigned to read●To ask about the suitability of a topic he wants to write about●To ask about the difference between chinampas and hydroponics2. What does the professor imply about hydroponics?●It was probably invented by the Aztecs.●It is a relatively modern development in agriculture.●It requires soil that is rich in nutrients.●It is most successful when extremely pure water is used.3. Why does the professor describe how chinampas were made?●To emphasize that the topic selected for a paper needs to be more specific●To encourage the student to do more research●To point out how much labor was required to build chinampas●To explain why crops grown on chinampas should not be considered hydroponic4. What does the professor think about the article the student mentions?●She is convinced that it is not completely accurate.●She believes it was written for readers with scientific backgrounds.●She thinks it is probably too short to be useful to the student.●She has no opinion about it, because she has not read it.5. What additional information does the professor suggest that the student include in his paper?● A comparison of traditional and modern farming technologies●Changes in the designs of chinampas over time●Differences in how various historians have described chinampas●Reasons why chinampas are often overlooked in history booksLecture 36. What does the professor mainly discuss?●Comparisons between land animals and ocean-going animals of the Mesozoic era●Comparisons between sauropods and modern animals●Possible reasons why sauropods became extinct●New theories about the climate of the Mesozoic era7. What point does the professor make when she compares blue whales to large land animals?●Like large land animals, blue whales have many offspring.●Like large land animals, blue whales have proportionally small stomachs.●The land environment provides a wider variety of food sources than the ocean.●The ocean environment reduces some of the problems faced by large animals.8. According to the professor, what recent finding about the Mesozoic era challenges an earlier belief?●Sauropod populations in the Mesozoic era were smaller than previously believed.●Oxygen levels in the Mesozoic era were higher than previously believed.●Ocean levels in the Mesozoic era fluctuated more than previously believed.●Plant life in the Mesozoic era was less abundant than previously believed.9. Compared to small animals, what disadvantages do large animals typically have? [Choose two answers]●Large animals require more food.●Large animals have fewer offspring.●Large animals use relatively more energy in digesting their food.●Large animals have greater difficulty staying warm.10. Why does the professor discuss gastroliths that have been found with sauropod fossils?●To show that much research about extinct animals has relied on flawed methods●To show that even an incorrect guess can lead to useful research●To give an example of how fossil discoveries have cast doubt on beliefs about modern animals ●To give an example of a discovery made possible by recent advances in technology11. What did researchers conclude from their study of sauropods and gastroliths?●That gastroliths probably helped sauropods to store large quantities of plant material in theirstomachs●That sauropods probably used gastroliths to conserve energy●That sauropods may not have used gastroliths to aid in their digestion●That sauropods probably did not ingest any stonesLecture 412. What is the lecture mainly about?●Various ways color theory is used in different fields●Various ways artists can use primary colors●Aspects of color theory that are the subject of current research●The development of the first theory of primary colors13. What does the professor imply about the usefulness of the theory of primary colors?●It is not very useful to artists.●It has been very useful to scientists.●It is more useful to artists than to psychologists.●It is more useful to modern-day artists than to artists in the past.14. Why does the professor mention Isaac Newton?●To show the similarities between early ideas in art and early ideas in science●To explain why mixing primary colors does not produce satisfactory secondary colors●To provide background information for the theory of primary colors●To point out the first person to propose a theory of primary colors15. According to the pro fessor, what were the results of Goethe’s experiments with color? [Choose two answers]●The experiments failed to find a connection between colors and emotions.●The experiments showed useful connections between color and light.●The experiments provided valuable information about the relationships between colors.●The experiments were not useful until modern psychologists reinterpreted them.16. According to the professor, why did Runge choose the colors red, yellow and blue as the three primary colors?●He felt they represented natural light at different times of the day.●He noticed that they were the favorite colors of Romantic painters.●He performed several scientific experiments that suggested those colors.●He read a book by Goethe and agreed with Goethe’s choices of colors.17. What does the professor imply when he says this?●Many people have proposed theories about primary colors.●Goethe discovered the primary colors by accident.●Goethe probably developed the primary color theory before reading Runge’s le tter.●Goethe may have been influenced by Runge’s ideas about primary colors.TPO-28Conversation 11. What is the conversation mainly about?●Criticisms of Dewey’s political philosophy●Methods for leading a discussion group●Recent changes made to a reference document●Problems with the organization of a paper2. Why is the student late for his meeting?●Seeing the doctor took longer than expected.●No nearby parking spaces were available.●His soccer practice lasted longer than usual.●He had problems printing his paper.3. What revisions does the student need to make to his paper? [Choose three answers]●Describe the influences on Dewey in more detail●Expand the introductory biographical sketch●Remove unnecessary content throughout the paper●Use consistent references throughout the paper●Add an explanation of Dewey’s view on individuality4. Why does the professor mention the political science club?●To encourage the student to run for club president●To point out that John Dewey was a member of a similar club●To suggest an activity that might interest the student●To indicate where the student can get help with his paper5. Why does the professor say this:●To find out how many drafts the student wrote●To encourage the student to review his own work●To emphasize the need for the student to follow the guidelines●To propose a different solution to the problemLecture 16. What is the lecture mainly about?●The importance of Locke’s views to modern philosophical thought●How Descartes’ view of knowledge influenced tre nds in Western philosophy●How two philosophers viewed foundational knowledge claims●The difference between foundationalism and methodological doubt7. Why does the professor mention a house?●To explain an idea about the organization of human knowledge●To illustrate the unreliability of our perception of physical objects●To clarify the difference between two points of view about the basis of human knowledge●To remind students of a point he made about Descartes in a previous lecture8. What did Locke believe to the most basic type of human knowledge?●Knowledge of one’s own existence●Knowledge acquired through the senses●Knowledge humans are born with●Knowledge passed down from previous generations9. According to the professor, what was Descartes’ purpose f or using methodological doubt?●To discover what can be considered foundational knowledge claims●To challenge the philosophical concept of foundationalism●To show that one’s existence cannot be proven●To demonstrate that Locke’s views were essentially corre ct10. For Descartes what was the significance of dreaming?●He believed that his best ideas came to him in dreams●He regarded dreaming as the strongest proof that humans exist.●Dreaming supports his contention that reality has many aspects.●Dreaming illustrates why human experience of reality cannot always be trusted.11. According to Descartes, what type of belief should serve as a foundation for all other knowledge claims?● A belief that is consistent with what one sees and hears● A belief that most other people share● A belief that one has held since childhood● A belief that cannot be falseLecture 212. What is the main purpose of the lecture?●To show that some birds have cognitive skills similar to those of primates●To explain how the brains of certain primates and birds evolved●To compare different tests that measure the cognitive abilities of animals●To describe a study of the relationship between brain size and cognitive abilities13. When giving magpies the mirror mark test, why did researchers place the mark on magpies’ throats?●Throat markings trigger aggressive behavior in other magpies.●Throat markings are extremely rare in magpies.●Magpies cannot see their own throats without looking in a mirror.●Magpies cannot easily remove a mark from their throats.14. According to the professor, some corvettes are known to hide their food. What possible reasonsdoes she provide for this behavior? [Choose two answers]●They are ensuring that they will have food to eat at a later point in time.●They want to keep their food in a single location that they can easily defend.●They have been conditioned to exhibit this type of behavior.●They may be projecting their own behavioral tendencies onto other corvids.15. What is the professor’s attitude toward the study on p igeons and mirror self-recognition?●She is surprised that the studies have not been replicated.●She believes the study’s findings are not very meaningful.●She expects that further studies will show similar results.●She thinks that it confirms what is known about magpies and jays.16. What does the professor imply about animals that exhibit mirror self-recognition?●They acquired this ability through recent evolutionary changes.●They are not necessarily more intelligent than other animals.●Their brains all have an identical structure that governs this ability.●They may be able to understand another animal’s perspective.17. According to the professor, what conclusion can be drawn from what is now known about corvettes’ brains?●The area in corvids’ brains tha t governs cognitive functions governs other functions as well.●Corvids’ brains have evolved in the same way as other birds’ brains, only more rapidly.●Corvids’ and primates’ brains have evolved differently but have some similar cognitive abilities.●The cognitive abilities of different types of corvids vary greatly.Conversation 21. Why does the man go to see the professor?●To learn more about his student teaching assignment●To discuss the best time to complete his senior thesis●To discuss the possibility of changing the topic of his senior thesis●To find out whether the professor will be his advisor for his senior thesis2. What is the man’s concern about the second half of the academic year?●He will not have time to do the necessary research for his senior thesis.●He will not be allowed to write his senior thesis on his topic choice.●His senior thesis advisor will not be on campus.●His student teaching requirement will not be complete before the thesis is due.3. What does the man imply about Professor Johnson?●His sabbatical may last longer than expected.●His research is highly respected throughout the world.●He is the English department’s specialist on Chaucer.●He is probably familiar with the literature of the Renaissance.4. Why does the man want to write his senior thesis on The Canterbury Tales? [Choose two answers]●He studied it during his favorite course in high school.●He has already received approval for the paper from his professor.●He thinks that the knowledge might help him in graduate school.●He has great admiration for Chaucer.5. Why does the professor say this:●She is uncertain whether the man will be able to finish his paper before the end of the summer.●She thinks the man will need to do a lot of preparation to write on a new topic.●She wants to encourage the man to choose a new advisor for his paper.●She wants the man to select a new topic for his paper during the summer.Lecture 36. What is the lecture mainly about?●The differences in how humans and plants sense light●An explanation of an experiment on color and wavelength●How plants sense and respond to different wavelengths of light●The process by which photoreceptors distinguish wavelengths of light7. According to the professor, what is one way that a plant reacts to changes in the number of hours of sunlight?●The plant absorbs different wavelengths of light.●The plant begins to flower or stops flowering.●The number of photoreceptors in the plant increases.●The plant’s rate of photosynthesis increases.8. Why does the professor think that it is inappropriate for certain wavelength of light to be named “far-red”?●Far-red wavelengths appear identical to red wavelengths to the human eye.●Far-red wavelengths have the same effects on plants as red wavelengths do.●Far-red wavelengths travel shorter distances than red wavelengths do.●Far-red wavelengths are not perceived as red by the human eye.9. What point does the professor make when she discusses the red light and far-red light that reaches plants?●All of the far-red light that reaches plants is used for photosynthesis.●Plants flower more rapidly in response to far-red light than to red light.●Plants absorb more of the red light that reaches them than of the far-red light.●Red light is absorbed more slowly by plants than far-red light is.10. According to the professor, how does a plant typically react when it senses a high ratio of far-red light to red light?●It slows down its growth.●It begins photosynthesis.●It produces more photoreceptors.●It starts to release its seeds.11. In the Pampas experiment, what was the function of the LEDs?●To stimulate photosynthesis●To simulate red light●To add to the intensity of the sunlight●To provide additional far-red lightLecture 412. What does the professor mainly discuss?●Evidence of an ancient civilization in central Asia●Archaeological techniques used to uncover ancient settlements●The controversy concerning an archaeological find in central Asia●Methods used to preserve archaeological sites in arid areas13. What point does the professor make about mound sites?●They are easier to excavate than other types of archaeological sites.●They often provide information about several generations of people.●They often contain evidence of trade.●Most have been found in what are now desert areas.14. Why does the professor compare Gonur-depe to ancient Egypt?●To point out that Gonur-depe existed earlier than other ancient civilizations●To emphasize that the findings at Gonur-depe are evidence of an advanced civilization●To demonstrate that the findings at these locations have little in common●To suggest that the discovery of Gonur-depe will lead to more research in Egypt15. What does the professor imply about the people of Gonur-depe?●They avoided contact with people from other areas.●They inhabited Gonur-depe before resettling in Egypt.●They were skilled in jewelry making.●They modeled their city after cities in China.16. Settlements existed at the Gonur-depe site for only a few hundred years. What does the professor say might explain this fact? [Choose two answers]●Wars with neighboring settlements●Destruction caused by an earthquake●Changes in the course of the Murgab River●Frequent flooding of the Murgab River17. What is the professor’s opinion about the future of the Gonur-depe site?●She believes it would be a mistake to alter its original form.●She doubts the ruins will deteriorate further.●She thinks other sites are more deserving of researchers’ attention.●She is not convinced it will be restored.TPO-29Conversation 11. What is the conversation mainly about?●What the deadline to register for a Japanese class is●Why a class the woman chose may not be suitable for her●How the woman can fix an unexpected problem with her class schedule●How first-year students can get permission to take an extra class2. Why does the man tell the woman that Japanese classes are popular?●To imply that a Japanese class is unlikely to be canceled●To explain why the woman should have registered for the class sooner●To encourage the woman to consider taking Japanese●To convince the woman to wait until next semester to take a Japanese class3. Why does the man ask the woman if she registered for classes online?●To explain that she should have registered at the registrar’s office●To find out if there is a record of her registration in the computer●To suggest a more efficient way to register for classes●To determine if she received confirmation of her registration4. What does the man suggest the woman do? [Choose two answers]●Put her name on a waiting list●Get the professor to sign a form granting her permission to take the class●Identify a course she could take instead of Japanese●Speak to the head of the Japanese department5. What does the man imply when he points out that the woman is a first-year student?●The woman has registered for too many classes.●The woman should not be concerned if she cannot get into the Japanese class●The woman should not register for advanced-level Japanese classes yet●The woman should only take required courses at this timeLecture 16. What does the professor mainly discuss?●Causes of soil diversity in old-growth forests●The results of a recent research study in a Michigan forest●The impact of pedodiversity on forest growth●How forest management affects soil diversity7. According to the professor, in what way is the soil in forested areas generally different from soil in other areas?●In forested areas, the soil tends to be warmer and moister.●In forested areas, the chemistry of the soil changes more rapidly.●In forested areas, there is usually more variability in soil types.●In forested areas, there is generally more acid in the soil.8. What does the professor suggest are the three main causes of pedodiversity in the old-growth hardwood forests she discusses? [Choose three answers]●The uprooting of trees●The existence of gaps●Current forest-management practices●Diversity of tree species●Changes in climatic conditions9. Why does the professor mention radiation from the Sun?●To point out why pits and mounds have soil with unusual properties●To indicate the reason some tree species thrive in Michigan while others do not●To give an example of a factor that cannot be reproduced in forest management●To help explain the effects of forest gaps on soil10. Why does the professor consider pedodiversity an important field of research?●It has challenged fundamental ideas about plant ecology.●It has led to significant discoveries in other fields.●It has implications for forest management.●It is an area of study that is often misunderstood.11. Why does the professor give the students an article to read?●To help them understand the relationship between forest dynamics and pedodiversity●To help them understand how to approach an assignment●To provide them with more information on pits and mounds●To provide them with more exposure to a controversial aspect of pedodiversityLecture 212. What is the main purpose of the lecture?●To explain how musicians can perform successfully in theaters and concert halls with pooracoustics●To explain how the design of theaters and concert halls has changed over time●To discuss design factors that affect sound in a room●To discuss a method to measure the reverberation time of a room13. According to the lecture, what were Sabine’s contr ibutions to architectural acoustics? [Choose two answers]●He founded the field of architectural acoustics.●He developed an important formula for measuring a room’s reverberation time.●He renewed architects’ interest in ancient theaters.●He provided support for using established architectural principles in the design of concert halls.14. According to the professor, what is likely to happen if a room has a very long reverberation time?●Performers will have to make an effort to be louder.●Sound will not be scattered in all directions.●Older sounds will interfere with the perception of new sounds.●Only people in the center of the room will be able to hear clearly.15. Why does the professor mention a piano recital? [Choose two answers]●To illustrate that different kinds of performances require rooms with different reverberationtimes●To demonstrate that the size of the instrument can affect its acoustic properties●To cite a type of performance suitable for a rectangular concert hall●To exemplify that the reverberation time of a room is related to its size16. According to the professor, what purpose do wall decorations in older concert halls serve?●They make sound in the hall reverberate longer.●They distribute the sound more evenly in the hall.●They make large halls look smaller and more intimate.●They disguise structural changes made to improve sound quality.17. Why does the professor say this:●To find out if students have understood his point●To indicate that he will conclude the lecture soon●To introduce a factor contradicting his previous statement●To add emphasis to his previous statementConversation 21. Why does the student go to see the professor?●To explain why he may need to hand in an assignment late●To get instruction on how to complete an assignment●To discuss a type of music his class is studying●To ask if he can choose the music to write about in a listening journal2. What does the student describe as challenging?●Comparing contemporary music to earlier musical forms●Understanding the meaning of songs that are not written in English●Finding the time to listen to music outside of class●Writing critically about musical works3. Why does the student mention hip-hop music?●To contrast the ways he responds to familiar and unfamiliar music。

是什么导致非理性行为的英语作文

是什么导致非理性行为的英语作文1. Non-rational behavior is often caused by a lack ofself-awareness.2. Peer pressure can lead to non-rational behavior in individuals.3. Impulsiveness and lack of self-control can be factors in non-rational behavior.4. Emotional distress or trauma can lead to non-rational behavior.5. Addiction to substances or behaviors can cause non-rational behavior.6. Cognitive biases and distorted thinking can contribute to non-rational behavior.7. Ignorance or lack of knowledge about a situation can lead to non-rational behavior.8. Insecurity and low self-esteem can be underlying causes of non-rational behavior.9. Cultural or societal influences can contribute to non-rational behavior in individuals.10. Environmental stressors can lead to non-rational behavior.11. Mental health disorders can cause non-rational behavior in individuals.12. Fear or anxiety can lead to non-rational behavior.13. Poor decision-making skills can contribute to non-rational behavior.14. Misinformation or propaganda can lead to non-rational behavior in individuals.15. Lack of critical thinking skills can be a cause of non-rational behavior.16. Lust or desire for material possessions can lead to non-rational behavior.17. Manipulation or coercion by others can cause non-rational behavior.18. Overconfidence in one's abilities can lead to non-rational behavior.19. The need for instant gratification can contribute to non-rational behavior.20. Biologically-based factors such as genetics or brain chemistry can cause non-rational behavior.21. Background stress can lead to non-rational behavior.22. Anger or frustration can cause non-rational behavior.23. Mental exhaustion can lead to non-rational behavior.24. Limited perspective or narrow-mindedness can contribute to non-rational behavior.25. Peer influence can lead to non-rational behavior.26. Financial stress can cause non-rational behavior.27. Lack of empathy can contribute to non-rational behavior.28. Unresolved past traumas can lead to non-rational behavior.29. Impatience can be a cause of non-rational behavior.30. Underdeveloped coping strategies can lead to non-rational behavior.31. Excessive pride or ego can contribute to non-rational behavior.32. Social or economic inequality can cause non-rational behavior.33. External pressures can lead to non-rational behavior.34. Fatigue or exhaustion can be a cause of non-rational behavior.35. Overwhelmed by emotions can lead to non-rational behavior.36. Insecurity or self-doubt can cause non-rational behavior.37. An unhealthy environment can lead to non-rational behavior.38. Exposure to violence or abuse can cause non-rational behavior.39. Pressure to conform can lead to non-rational behavior.40. Fear of failure can contribute to non-rational behavior.41. Loneliness or isolation can cause non-rational behavior.42. Lack of support systems can lead to non-rational behavior.43. Lack of moral compass can contribute to non-rational behavior.44. Unmet psychological needs can lead to non-rational behavior.45. Power struggles and conflict can cause non-rational behavior.46. Provocation by others can lead to non-rational behavior.47. Avoidance of responsibility can contribute to non-rational behavior.48. Escapism can cause non-rational behavior.49. Unrealistic expectations can lead to non-rational behavior.50. Competitive or hostile environments can contribute to non-rational behavior.51. Discrimination or prejudice can cause non-rational behavior.52. Influence of negative role models can lead to non-rational behavior.53. Psychological defense mechanisms can contribute to non-rational behavior.54. Lack of emotional intelligence can cause non-rational behavior.55. Addiction to technology can lead to non-rational behavior.56. Adverse childhood experiences can contribute to non-rational behavior.57. Imposter syndrome can cause non-rational behavior.58. Social comparison and envy can lead to non-rational behavior.59. Overwhelmed by responsibilities can contribute to non-rational behavior.60. Political or ideological indoctrination can cause non-rational behavior.61. Bullying or harassment can lead to non-rational behavior.62. Lack of positive coping mechanisms can contribute to non-rational behavior.63. Unrealistic societal ideals can cause non-rational behavior.64. Victim mentality can lead to non-rational behavior.65. Lack of resilience can contribute to non-rational behavior.66. Trauma responses can cause non-rational behavior.67. Influence of mass media and advertising can lead to non-rational behavior.68. Limited access to mental health resources can contribute to non-rational behavior.69. Influence of extremist ideologies can cause non-rational behavior.70. Unrealistic beauty standards can lead to non-rational behavior.71. Entitlement can contribute to non-rational behavior.72. Pressure to achieve perfection can lead to non-rational behavior.73. Social media influence can cause non-rational behavior.74. Disconnection from nature can contribute to non-rational behavior.75. Instability in personal relationships can lead to non-rational behavior.76. Limited exposure to diverse perspectives can cause non-rational behavior.77. Fear of rejection or abandonment can contribute to non-rational behavior.78. Limiting beliefs and self-sabotage can lead to non-rational behavior.79. Lack of passion or purpose can cause non-rational behavior.80. Peer shaming and ostracism can lead to non-rational behavior.81. Power imbalances can contribute to non-rational behavior.82. Environmental degradation can cause non-rational behavior.83. Lack of spiritual connection can contribute to non-rational behavior.84. Perceived threats to one's identity can lead to non-rational behavior.85. Lack of appreciation for diversity can cause non-rational behavior.86. Economic instability can contribute to non-rational behavior.87. Political polarization can lead to non-rational behavior.88. Unresolved conflicts can cause non-rational behavior.89. Loss of meaning or existential crises can contribute to non-rational behavior.90. Exposure to negative news and information can leadto non-rational behavior.91. Disproportionate focus on superficial values can cause non-rational behavior.92. Lack of access to education and information can contribute to non-rational behavior.93. Stagnation or lack of personal growth can lead to non-rational behavior.94. Escalation of minor conflicts can cause non-rational behavior.95. Lack of sense of belonging or community can contribute to non-rational behavior.96. Overwhelmed by societal expectations can lead tonon-rational behavior.97. Unrealistic portrayals in media and entertainment can cause non-rational behavior.98. Environmental pollution can contribute to non-rational behavior.99. Lack of connection to cultural heritage can lead to non-rational behavior.100. Pressure to conform to traditional gender roles can cause non-rational behavior.101. Disconnection from one's own emotions can lead to non-rational behavior.102. Limitation of personal freedoms can contribute to non-rational behavior.103. Influence of extremist groups can cause non-rational behavior.104. Hypercompetitive nature of society can lead to non-rational behavior.105. Lack of access to healthcare and mental health services can contribute to non-rational behavior.106. False sense of entitlement can cause non-rational behavior.107. Pressure from external expectations can lead to non-rational behavior.。

2022年考研考博-考博英语-西南交通大学考试全真模拟易错、难点剖析AB卷(带答案)试题号：60

2022年考研考博-考博英语-西南交通大学考试全真模拟易错、难点剖析AB卷（带答案）一.综合题(共15题)1.单选题Women have significant advantages over men in space because they need less food and less oxygen and they（）radiation better.问题1选项A.stand in withB.stand in forC.stand up forD.stand up to【答案】D【解析】句意:在太空中，女性比男性有着显著的优势，因为她们需要的食物和氧气更少，而且她们更能抵抗辐射。

考查短语辨析。

stand in with 与……联合，合谋;stand in for 代替; stand up for 支持，坚持，stand up to 经得起，抵抗。

空格处的宾语是“辐射”，因此D项正确。

2.单选题It was obvious that she and her husband were（）and she wished she'd never married him.问题1选项A.insolvableB.insensibleC.inseparableD.incompatible【答案】D【解析】句意:很明显她和她丈夫是水火不相容的，她希望自己从来没有嫁给他。

考查形容词辨析。

insolvable不能解决（答）的;insensible 昏迷的，无知觉的；inseparable 不可分离的；incompatible 不相容的，矛盾的。

根据后半句“她希望自己从来没有嫁给他”可知D符合句意。

3.单选题They （） so tired if they （）for a whole day.问题1选项A.wouldn’t feel, didn’t walkB.wouldn't feel, weren’t walking.C.wouldn't be feeling, weren’t walkingD.wouldn't be feeling, hadn’t been walking【答案】D【解析】考查虚拟语气。

2022年考研考博-考博英语-浙江大学考试全真模拟易错、难点剖析B卷(带答案)第50期

2022年考研考博-考博英语-浙江大学考试全真模拟易错、难点剖析B卷（带答案）一.综合题(共15题)1.单选题While Apple was coming under increasing pressure from lower cost PC clones, the company's initial response was to develop even more ( ) high-end computers.问题1选项A.sophisticatedB.luxuriousC.philosophicalD.sensitive【答案】A【解析】sophisticated复杂的，精致的；luxurious奢侈的，丰富的；philosophical哲学的；sensitive 敏感的。

句意：尽管苹果正面临来自低成本电脑复制品的越来越大压力，但该公司最初的反应是开发更复杂的高端电脑。

选项A符合句意。

2.单选题Whoever has skills and knowledge in this country, I believe, should be properly treated and rewarded（） his educational background and family origin.问题1选项A.despite ofB.regardless ofC.let aloneD.because of【答案】B【解析】despite of尽管；regardless of不管，不顾； let alone更不用说，听任；because of因为，由于。

句意：我认为，在这个国家无论谁拥有技术和知识，无论他的教育背景和家庭出身如何，都应该得到适当的对待和奖励。

选项B符合句意。

3.单选题Only in recent years（）begun to realize that wild dogs, kept within bounds, often do more good than harm.问题1选项A.people haveB.since people haveC.have peopleD.people who have【答案】C【解析】倒装结构。

2022年考研考博-考博英语-中国社会科学院考试全真模拟易错、难点剖析AB卷(带答案)试题号：68

2022年考研考博-考博英语-中国社会科学院考试全真模拟易错、难点剖析AB卷（带答案）一.综合题(共15题)1.单选题The founders, as was the case of almost all their successors, were long on exhortation and rhetoric regarding the value of civic education, but they left it to the textbook writers to distill the essence of those values for school children.问题1选项A.infuseB.disseminateC.extractD.demonstrate【答案】C【解析】划线词的宾语是the essence of those values for school children，从那些价值观中……本质。

A选项infuse“灌输；浸渍”；B选项disseminate“宣传；散步”；C选项extract“提取；提炼”；D选项demonstrate“证明；展示”。

联系句意可知“从那些价值观中提取本质”逻辑通顺，因此C选项符合题意。

2.单选题Gender-based violence encompasses a wide range of human rights violations, including sexual abuse of children, rape, domestic violence, sexual assault and harassment, trafficking of women and girls and several harmful traditional practices.问题1选项A.batteringB.tradingC.veneratingD.craving【答案】B【解析】句意：基于性别的暴力包括广泛的侵犯人权行为，包括对儿童的性虐待、强奸、家庭暴力、性侵犯和骚扰、……妇女和女童以及若干有害的传统做法。

Differencesbetwe...

Differencesbetwe...Language can be considered the major characteristic which separates man from other living creatures. The presence of a language in a non-human species would clearly be inconceivable a philosopher such as Descartes. Whilst it cannot be argued that the human languages are very complex systems with many rules and infinite possibilities of utterances, there are some methods of communication of animals that are comparable to human language, which thus casts some degree of doubt on this supposed human-specificity of language. Semanticity is a suggested test for the language ability of any species. It is the use of symbols to 'mean' or refer to objects and actions. Some writers have claimed that semanticity is exclusively human. Whilst it is possible that animals may only be able to communicate about a total situation, it is difficult to be certain; as is shown by the calls of the velvet monkey. I am therefore going to consider several examples of non-human animal communications, both vocalizations and other methods, and test them for semanticity.Gibbons are several species of our closest surviving non-human kin. Like humans, they communicate in various ways, including posturing and gesturing, but the most language-like of their communication is their system of calls. Investigations of the gibbons of northern Thailand have shown that these gibbons have a stock of at least nine different calls. One of these is emitted typically when the group is surprised by a possible enemy and takes the form of a high pitched shout; it is often repeated by those who hear it and all act accordingly in order to avoid the danger of the enemy. An entirely different sort of call occurs in connection with friendly approaches among young gibbons, and reinforces the notion of play.A third call seems to serve to keep the members of a group close enough together as they move through the woods in search of food. The most important property of this system of communication is its lack of flexibility. Whatever the exact number of calls Mbt Shoes Sale is, it is finite and small. Whilst any one of the calls can be varied in loudness or in the number of repetitions, no matter what situation a gibbon may encounter, its vocal reaction is constrained to be one of this small finite number: a gibbon does not react to a new situation by producing a new call or putting together two or more of the calls already available.It has been suggested that language grew out of a primate call system, like the ones used by apes today and the one I have described that is used by gibbons. It is assumed that humans started out with a simple set of cries in which each one meant something different, such as, "Danger!" or "Follow me!". These cries gradually became more elaborate and eventually evolved into language. A possible intermediate stage is seen in the cries of the vervet monkey. This monkey has several alarm calls which distinguish between different types of danger. According to some, it is a very short step froman alarm call warning of a poisonous snake to using the chutter as a 'word' signifying a poisonous snake. However, another interpretation of these signals is possible; a distinguishing between the intensity of different types of danger. However an experiment in which a concealed loudspeaker plated recordingsof the alarm calls showed that when each sound was heard, a specific response was seen.For example, when they heard the chutter, the vervets stood on their hind legs and looked around for a snake. This implies that the monkeys clearly have a special signal for each type of enemy; each signal has semantic properties.It is perhaps unfair to concentrate on primates. Compared with these, bees and dolphins have extremely sophisticated communication systems. Whilst the majority of bee communication is achieved through dance rather a system of sound signals, I feel that there is some evidence in this example Mbt Shoes that casts some degree of doubt on the supposed human-specificity of language. When a worker bee finds a source of nectar, it returns to the hive and performs a dance. It has been shown that certain features of the dance transmit information about the location of the source of nectar: one feature specifies the direction of the source from the hive in relation to the position of the sun, another specifies its distance.It has been decided that these dances are performed and understood on the basis of instinct: the semantic conventions of the system are innate, and do not have to be learned or taught. Using this system, a worker can report on a source of nectar at a location to which none of the colony has ever previously been. To a certain extent, therefore, the system is flexible. Whilst it appears that bees cannot communicate about anything except nectar - or, if they do, it is via other equally specialised small systems, the claim that bee dancing possesses creativity does not appear to be exaggerated since, at least in theory, an infinite amount of unpredictable and appropriate information relating to the parameters of direction and distance can be transmitted. However, the idea of verticality, for instance, expressed by the English word 'up' cannot be expressed, nor can complex thoughts and feelings present in human philosophy, literature and science. The difference in the creativity of the'language' of the bee and human language is an important one, yet despite his claim for the exclusiveness of language creativity to humans, Chomsky explicitly recognizes the possibility that certain ideas, concepts and feeling may well be inexpressible in human language. This situation mirrors the fact that there are many things which cannot be expressed in the 'language' of the bee.Like bees, dolphins do not have a 'creative' communication system in the human sense - even though they make underwater 'clicks' which are surprisingly sophisticated. These clicks are intermittent bursts of sound, each of which lasts less than athousandth of a second, in frequencies beyond the range of human hearing. By listening for their echoes, a dolphin can find a tiny eel in a bed of mud or a tiny fish seventy meters away. The dolphin first sends out a very general click, and then progressively modifies it as it gets echoes back, so allowing it to get more and more accurate information. As far as we know, a dolphin's communication is restricted to the size and location of shapes, though a possibility is that a progressively modifiedclick might end up being the 'name' for the object finally pinpointed; semantic properties for dolphin communication may evolve.Human language is a signaling system which uses sounds and this is a characteristic shared by a large number of animal systems. Animals that use vocal signals have a stock of basic sounds which vary according to their species. A cow has fewer than ten, a chicken has around twenty, dolphins and apes have between twenty and thirty and the impressive vervet monkey has thirty-six. In animal communication, there is frequently a connection, arguably semantic, between the signal and the message sent. Whilst most animals can use each basic sound only once or in very few simple combinations, human language works differently. Each language has a stock of phonemes which are similar in number to the basic sounds possessed by animals; usually between thirty and forty. The difference is that normally these phonemes are meaningless in isolation and only gain meaning when they are combined with other phonemes.So, whilst Chomsky's concept of creativity, the ability to produce novel utterances, seems not to be present in any natural communication system possessed by animals, all systems of communication, human or otherwise, appear to be innately guided. That is, a frog will inevitably croak, cows will inevitably moo and humans will inevitably talk. The important thing to realize is that, whilst there are many species for which vocalizations seem to have no solid semantic properties - a cat will purr to express happiness, there are some animal systems of communication, such as that of vervet monkeys, which arguably share with human the arbitrary nature of the connection between the signified and the signifier, developed by Saussure, and thus can be argued to have semantic properties.Mary Anne Winslow is a member of Essay Writing Service counselling department team and a dissertation writing consultant. Contact her to get free counselling o n custom essay writing.。

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ut + f (u)x ? uxx = 0;
(1.2)
A completely di erent behavior is observed if (1.1) is approximated by the KdV equation
ut + f (u)x ? uxxx = 0; > 0;
as > 0 tends to zero 7]. Entropy solutions can be also characterized as the weak solutions of (1.1) which satisfy the Oleinik one-sided Lipschitz condition (OSLC) 1: ux(t; x) (1.3) t (1.4)
2 4
4 5
3 Properties of the Model Equation
6
6 6 8
பைடு நூலகம்
4 Strong Convergence? 5 Study of the Spurious Numerical Oscillations
y
8 12
Universite Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France; Email: brenier@dmi.ens.fr z Departement de Mathematiques et d'Informatique, Ecole Normale Superieure, 45 rue d'Ulm, 75230 Paris Cedex 05, France; Email: dlevy@dmi.ens.fr
E COLE NORMALE SUPERIEURE
________________________
Dissipative behavior of some fully non-linear KdV-type equations Yann BRENIER Doron LEVY
LMENS - 98 - 19
1
1 Introduction
Let us consider the rst-order non-linear evolution PDE
ut + f (u)x = 0;
(1.1)
with a strictly convex non-linearity f 00(u) > 0, typically f (u) = u2 =2 which corresponds to the usual inviscid Burgers equation 8]. This equation generally produces shock waves in a nite time and solutions must be understood in a suitable weak sense. A good framework enforcing existence, uniqueness, L1 stability, ( 7], 5], 6],...) is provided by the so-called entropy solutions, obtained through the vanishing viscosity method by passing to the limit in the viscous approximation
term proportional to x, which enables us to hold a xed while eliminating the RHS at the limit ! 0. The analytical tools available to study fully non-liner evolution PDEs such as (0.1){ (1.5) seem to be limited and a rigorous theory is, in our opinion, a very challenging task that deserves to be further addressed. Our main results are based on numerical evidences. The simple non-linear switch in the third-order term juxxjx based on the sign of the second derivative uxx, has a major impact. The same holds true for other nonlinear third-order operators such as (u2 )x. Instead of the usual dispersive wave-train xx that develops in the KdV equation, here we still observe the appearance of a single ripple, which indeed can be still considered as a dispersive phenomenon. This ripple, however, is of a totally di erent character than what we are familiar with in the KdV equation. Instead of developing into a full wave-train which propagates in time, this ripple remains single during the evolution of the solution. It does not increase above a certain size which is related to the value of the parameter in (0.1). The striking numerical discovery is that not only this ripple is single, but it also disappears in the limit ! 0. It turns that (0.1) is much closer in its behavior to the dissipative, viscous approximations of the form
Contents
1 Introduction 2 Motivation
2.1 The Model Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 The Numerical Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Scalings, Invariance and Similarity Solutions . . . . . . . . . . . . . . . . 3.2 Traveling Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 The One-Sided Lipschitz Condition . . . . . . . . . . . . . . . . . . . . .
as investigated by many authors, in particular 4]. When the formal limit has shocks, the corresponding solution of the KdV equation becomes highly oscillatory and does not converge at all to the entropy solution (even in a weak sense). An alternative approach of approximating equations such as (1.1) is to design a numerical scheme. In 1] Brenier and Osher presented a second-order accurate version of the Roe scheme ( 7], 5]) and an OSLC consistent method of lines for approximating solutions of scalar conservation laws, (1.1). As was already pointed out in 1], the \modi ed equation" of this scheme (that is to say the asymptotic PDE of the discrete equation) is of interest since (as it is second-order) it must involve, just like the KdV equation, a third-order term, but unlike the KdV equation, due to the enforced OSLC this third-order term must enforce restrictions on the possible creation of wiggles. Our present work presents an extended numerical study of these \non-classical dispersive" e ects, as well as an extended study of the numerics involved. The model equations we consider are (0.1) where g is concave and even, typically g (s) = ?jsj and the smoother g (s) = ?s2 . The numerical tools taken from 1] enable us to approximate the solutions of (0.1) with a numerical method in which its modi ed equation takes the desired form of