Design of a 2DOF vibrational energy harvesting device
机械外文翻译中英文
翻译：英文原文Definitions and Terminology of VibrationvibrationAll matter-solid, liquid and gaseous-is capable of vibration, e.g. vibration of gases occurs in tail ducts of jet engines causing troublesome noise and sometimes fatigue cracks in the metal. Vibration in liquids is almost always longitudinal and can cause large forces because of the low compressibility of liquids, e.g. popes conveying water can be subjected to high inertia forces (or “water hammer”) when a valve or tap is suddenly closed. Excitation forces caused, say by changes in flow of fluids orout-of-balance rotating or reciprocating parts, can often be reduced by attention to design and manufacturing details. Atypical machine has many moving parts, each of which is a potential source of vibration or shock-excitation. Designers face the problem of compromising between an acceptable amount of vibration and noise, and costs involved in reducing excitation.The mechanical vibrations dealt with are either excited by steady harmonic forces ( i. e. obeying sine and cosine laws in cases of forced vibrations ) or, after an initial disturbance, by no external force apart from gravitational force called weight ( i.e. in cases of natural or free vibrations). Harmonic vibrations are said to be “simple” if there is only one frequency as represented diagrammatically by a sine or cosine wave of displacement against time.Vibration of a body or material is periodic change in position or displacement from a static equilibrium position. Associated with vibration are the interrelated physical quantities of acceleration, velocity and displacement-e. g. an unbalanced force causes acceleration (a = F/m ) in a system which, by resisting, induces vibration as a response. We shall see that vibratory or oscillatory motion may be classified broadly as (a) transient; (b) continuing or steady-state; and (c) random.Transient Vibrations die away and are usually associated with irregulardisturbances, e. g. shock or impact forces, rolling loads over bridges, cars driven over pot holes-i. e. forces which do not repeat at regular intervals. Although transients are temporary components of vibrational motion, they can cause large amplitudes initially and consequent high stress but, in many cases, they are of short duration and can be ignored leaving only steady-state vibrations to be considered.Steady-State Vibrations are often associated with the continuous operation of machinery and, although periodic, are not necessarily harmonic or sinusoidal. Since vibrations require energy to produce them, they reduce the efficiency of machines and mechanisms because of dissipation of energy, e. g. by friction and consequentheat-transfer to surroundings, sound waves and noise, stress waves through frames and foundations, etc. Thus, steady-state vibrations always require a continuous energy input to maintain them.Random Vibration is the term used for vibration which is not periodic, i. e. has no made clear-several of which are probably known to science students already.Period, Cycle, Frequency and Amplitude A steady-state mechanical vibration is the motion of a system repeated after an interval of time known as the period. The motion completed in any one period of time is called a cycle. The number of cycles per unit of time is called the frequency. The maximum displacement of any part of the system from its static-equilibrium position is the amplitude of the vibration of that part-the total travel being twice the amplitude. Thus, “amplitude” is not synonymous with “displacement” but is the maximum value of the displacement from the static-equilibrium position.Natural and Forced Vibration A natural vibration occurs without any external force except gravity, and normally arises when an elastic system is displaced from a position of stable equilibrium and released, i. e. natural vibration occurs under the action of restoring forces inherent in an elastic system, and natural frequency is a property of he system.A forced vibration takes place under the excitation of an external force (or externally applied oscillatory disturbance) which is usually a function of time, e. g.in unbalanced rotating parts, imperfections in manufacture of gears and drives. The frequency of forced vibration is that of the exciting or impressed force, i. e. the forcing frequency is an arbitrary quantity independent of the natural frequency of the system.Resonance Resonance describes the condition of maximum amplitude. It occurs when the frequency of an impressed force coincides with, or is near to a natural frequency of the system. In this critical condition, dangerously large amplitudes and stresses may occur in mechanical systems but, electrically, radio and television receivers are designed to respond to resonant frequencies. The calculation or estimation of natural frequencies is, therefore, of great importance in all types of vibrating and oscillating systems. When resonance occurs in rotating shafts and spindles, the speed of rotation is known as the critical speed. Hence, the prediction and correction or avoidance3 of a resonant condition in mechanisms is of vital importance since, in the absence of damping or other amplitude-limiting devices, resonance is the condition at which a system gives an infinite response to a finite excitation.Damping Damping is the dissipation of energy from a vibrating system, and thus prevents excessive response. It is observed that a natural vibration diminishes in amplitude with time and, hence, eventually ceases owing to some restraining or damping influence. Thus if a vibration is to be sustained, the energy dissipated by damping must be replaced from an external source.The dissipation is related in some way to the relative motion between the components or elements of the system, and is caused by frictional resistance of some sort, e.g. in structures, internal friction in material, and external friction caused by air or fluid resistance called “viscous” damping if the drag force is assumed proportional to the relative velocity between moving parts. One device assumed to give viscous damping is the “dashpot” which is a loosely fitting piston in a cylinder so that fluid can flow from one side of the piston to the other through the annular clearance space.A dashpot cannot store energy but can only dissipate it.Basic Machining Operations and Machine ToolsBasic Machining OperationsMachine tools have evolved from the early foot-powered lathes of the Egyptians and John Wilkinson’s boring mill. They are designed to provide rigid support for both the workpiece and the cutting tool and can precisely control their relative positions and the velocity of the tool with respect to the workpiece. Basically, in metal cutting, a sharpened wedge-shaped tool removes a rather narrow strip of metal from the surface of a ductile workpiece in the form of a severely deformed chip. The chip is a waste product that is comsiderably shorter than the workpiece from which it came but woth a corresponding increase in thickness of the uncut chip. The geometrical shape of the machine surface depedns on the shape of the tool and its path during the machinig operation.Most machining operations produce parts of differing geometry. If a rough cylindrical workpiece revolves about a central axis and the tool penetrates beneath its surface and travels parallel to the center of rotation, a surface of revolution is producedand the operation is called turning. If a hollow tube is machined on the inside in a similar manner, the operation is called boring. Producing an external conical surface of uniformly varying diameter is called taper turning. If the tool point travels in a path of varying radius,a contoured surface like that of a bowling pin a can be produced; or, if the piece is short enough and the support is sufficiently rigid, a contoured surface could be produced by feeding a shaped tool normal to the axis of rotation. Short tapered or cylindrical surfaces could also be contour formed.Flat or plane surfaces are frequently required. The can be generated by adial turning or facing, in which the tool point moves normal to the axis of rotation. In other cases, it is more convenient to hold the workpiece steady and reciprocate the tool across it in a series of straight-line cuts with a crosswise feed increment before each cutting stroke. This operation is called planing and is carried out on a shaper. For larger pieces it is easier to keep the tool stationary and draw the workpiece under it as inplaning. The tool is fed at each reciprocation. Contoured surfaces can be produced by using shaped tools.Multiple-edged tools can also be used. Drilling uses a twin-edged fluted tool for holes with depths up to 5 10times the drill diameter. Whether the dril turns or the workpiece rotates, relative motion between the cutting edge and the workpiece is the important factor. In milling operations a rotary cutter with a number of cutting edges engages the workpiecem which moves slowly with respect to the cutter. Plane or contoured surfaces may be produced, depending on the geometry of the cutter and the type of feed. Horizontal or vertical axes of rotation ma be used, and the feed of the workpiece may be in any of the three coordinate directions.Basic Machine ToolsMachine tools are used to produce a part of a specified geometrical shape and precise size by removing metal from a ductile materila in the form of chips. The latter are a waste product and vary from long continuous ribbons of a ductile material such as steel, which are undesirable from a disposal point of view, to easily handled well-broken chips resulting from cast iron. Machine tools perform five basic metal-removal processes: turning, planing, drilling, milling, and frinding. All other metal-removal processes are modifications of these five basic processes. For example, boring is internal turning;reaming,tapping, and counterboring modify drilled holes and are related to drilling; hobbing and gear cutting are fundamentally milling operations; hack sawong and broaching are a form of planing and honing; lapping, superfinishing, polishing, and buffing are avariants of grinding or abrasive removal operations. Therefore, there are only four types of basic machine tools, which use cutting tools of specific controllable feometry: thes, 2.planers, 3.drilling machines, and ling machines. The frinding process forms chips, but the geometry of the barasive grain is uncontrollable.The amount and rate of material removed by the various machining processes may be large, as in heavy truning operations, or extremely small, as in lapping or superfinishing operations where only the high spots of a surface are removed.A machine tool performs three major functions: 1.it rigidly supports the workpiece orits holder and the cutting tool; 2. it provedes relative motion between the workpiece and the cutting tools; 3. it provides a range of feeds and speeds usually ranging from 4 to 32 choices in each case.Speed and Feeds in MachiningSpeeds feeds, and depth of cut are the three major variables for economical machining. Other variables are the work and tool materials, coolant and geometry of the cutting tool. The rate of metal removal and power required for machining depend upon these variables.The depth of cut, feed, and cutting speed are machine settings that must be established in any metal-cutting operation. They all affect the forces, the power, and the rate of metal removal. They can be defined by comparing them to the needle and record of a phonograph. The cutting speed is represented by the velocity of the record surface relative to the needle in the tone arm at any instant. Feed is represented by the advance the needle radially inward per revolution, or is the difference in position between two adjacent grooves.Turning on Lathe CentersThe basic operations performed on an engine lathe are illustrated in Fig. Those operations performed on extemal surfaces with a single point cutting tool are called turning. Except for drilling, reaming, and tapping, the operations on intermal surfaces are also performed by a single point cutting tool.All machining operations, including turning and boring, can be classified as roughing, finishing, or semi-finishing. The objective of a roughing ooperation is to remove the bulk of the material sa repidly and as efficiently as possible, while leaving a small amount of material on the work-piece for the finishing operation. Finishing operations are performed to btain the final size, shape, and surface finish on the workpiece. Sometimes a semi-finishing operation will precede the finishing operation to leave a small predetermined and uniform amount of stoxd on the work-piece to be removed by the finishing operation.Generally, longer workpieces are turned while supported on one or two lathe centers. Cone shaped holes, called center holes, which fit the lathe centers are drilled in the ends of the workpiece-usually along the axis of the cylindrical part. The end of the workpiece adjacent to the tailstock is always supported by a tailstock center, while the end near the headstock may be supported by a headstock cener or held in a chuck. The headstock end of the workpiece may be held in a four-jar chuck, or in a collet type chuck. This method holds the workpiece firmly and transfers the power to the workpiece smoothly; the additional support to the workpiece priovided by the chuck lessens the tendency for chatter to occur when cutting. Precise results can be obtained with this method if care is taken to hold the workpiece accurately in the chuck.Very precise results can be obtained by supporting the workpiece between two centers.A lathe dog is clamped to the workpiece; together they are driven by a driver p;ate mounted on the spindle nose. One end of the workpiece is machined; then the workpiece can be turned around in the lathe to machine the other end. The center holes in the workpiece serve as precise locating surfaces as well as bearing surfaces to carry the weight of the workpiece and to resist the xutting forces. After the workpiece has been removed from the lathe for any reason, the center holes will accurately align the workpiece back in the lathe or in another lathe,or in a cylindrical grinding machine. The workpiece must never be held at the headstock end by both a chuck and a lathe center. While at first thought this seems like a quick method of aligning the workpiece in the chuck, this must not be done because it is not possible to press evenly with the jaws against the workpiece while it is also supported by the center. The alignment provided by the center will not be maintained and the pressure of the jaws may damage the center hole, the lathe center,and prehaps even the lathe spindle. Compensatng or floating jaw chucks used almost exclusively on high production work provice an exception to the statements made above. These chucks are really work drivers and cannot be used for the same purpose as ordinary three or four=jaw chucks. While very large diameter workpieces are sometimes mounted on two centers, they are preferably held at the headstock end by faceplate jaes to obtain the smooth power transmission; moreover, large lathe dogs that are adequate to transmit the power notgenerally available, although they can be maed as a special. Faceplate jaws are like chuck jaws except that thet are mounted on a faceplate, which has less overhang from the spindle bearings than a large chuck would have.BoringThe boring operation is generally performed in two steps; namely, rough boring and finish boring. The objective of the rough-boring operation is to remove the excess metal rapidly and efficiently, and the objective of the finish-boring operation is to obtain the desired size, surface finish, and location of the hole. The size of the hole is obtained by using the trial-cut procedure. The diameter of the hole can be measured with inside calipers and outside micrometer calipers. Basic Measuring Insteruments, or inside micrometer calipers can be used to measure the diameter directly.Cored holes and drilled holes are sometimes eccentric wwith respect to the rotation of the lathe. When the boring tool enters the work, the boring bar will take a deeper cut on one side of the hole than on the other, and will deflect more when taking this deeper cut,with the result that the bored hole will not be concentric with the rotation of the work. This effect is corrected by taking several cuts through the hole using a shallow depth of cut. Each succeeding shallow cut causes the resulting hole to be more concentric than it was with the previous cut. Before the final, finish cut is taken, the hole should be concentric with the rotation of the work in order to make certain that the finished hole will be accurately located.Shoulders, grooves, contours, tapers, and threads are bored inside of holes. Internal grooves are cut using a tool that is similar to an external grooving tool. The procedure for boring internal shoulders is very similar to the procedure for turning rge shoulders are faced with the boring tool positioned with the nose leading, and using the cross slide to feed the tool. Internal contours can be machined using a tracing attachment on a lathe. The tracing attachment is mounted on the cross slide and the stylus follows the outline of the master profile plate. This causes the cutting tool to move in a path corresponding to the profile of the master profile plate.Thus, the profile on the master profile plate is reproduced inside the bore. The master profile plate is accurately mounted on a special slide which can be precisely adjusted in two dirctions, in two directionsm, in order to align the cutting tool in the correct relationship to the work. This lathe has a cam-lick type of spindle nose which permits it to take a cut when rotating in either direction. Normal turning cuts are taken with the spindle rotating counterclockwise. Thie boring cut is taken with the spindle revolving in a clockwise direction, or “backwards”. This permits the boring cut to be taken on the “back side” of the bore which is easier to see from the operator’sposition in front of the lathe. This should not be done on lathes having a threaded spindle nose because the cutting force will tend to unscrew the chuck.中文翻译振动的定义和术语振动所有的物质---固体，液体和气体-----都能够振动，例如，在喷气发动机尾部导管中产生的气体振动会发出令人讨厌的噪声，而且有时还会使金属产生疲劳裂缝。
Extracting the Maxwell charge from the Wheeler-DeWitt equation
ˆΣ Ψ d3 xQ Ψ|Ψ
Ψ =−
Σ
d3 x
3 gT
αβ u
α β
u
Ψ . (13)
2 Ψ|Ψ
Eq.(13) has been obtained by multiplying Eq.(11) by Ψ∗ [gij ] and by functionally integrating over the three spatial metric gij . To fix the ideas, let us consider the electric case. Thus, if we substitute the expression (8) into Eq.(13), we get Ψ
Extracting the Maxwell charge from the Wheeler-DeWitt equation
Remo Garattini∗
Universit` a degli Studi di Bergamo, Facolt` a di Ingegneria, Viale Marconi 5, 24044 Dalmine (Bergamo) Italy and and I.N.F.N. - sezione di Milano, Milan, Italy. We consider the Wheeler-De Witt equation as a device for finding eigenvalues of a Sturm-Liouville problem. In particular, we will focus our attention on the electric (magnetic) Maxwell charge. In this context, we interpret the Maxwell charge as an eigenvalue of the Wheeler-De Witt equation generated by the gravitational field fluctuations. A variational approach with Gaussian trial wave functionals is used as a method to study the existence of such an eigenvalue. We restrict the analysis to the graviton sector of the perturbation. We approximate the equation to one loop in a Schwarzschild background and a zeta function regularization is involved to handle with divergences. The regularization is closely related to the subtraction procedure appearing in the computation of Casimir energy in a curved background. A renormalization procedure is introduced to remove the infinities together with a renormalization group equation.
Energy Harvesting
Harvester technologies
The most promising micro-harvesting technologies extract energy from vibration, temperature differentials and light. A fourth possibility – scavenging energy from RF emissions – is interesting, but the energy availability is at least an order of magnitude less than that of the first three. Estimates vary, but Figure 2 shows the approximate amount of energy per unit available from four micro-harvesting sources.
Executive summary
Macro-scale energy harvesting technologies in the form of windmills, watermills and passive solar power systems have been around for centuries. Now, as designers seek to cut the cords, they turn to microenergy harvesting systems that can scavenge milliwatts from solar, vibrational, thermal and biological sources. However, understanding ultra-low power from the sourcing side brings challenges as harvested power derived from ambient sources tends to be unregulated, intermittent and small.
叶片边柱锁原理
叶片边柱锁原理The principle of blade edge pillar lock is an essential component in the design and functionality of various mechanical systems. 叶片边柱锁原理在各种机械系统的设计和功能中起着至关重要的作用。
It is a mechanism that ensures the secure attachment of blades to a central hub or structure, allowing for efficient and reliable operation. 它是一种机制，确保叶片安全地连接到中心轴或结构，从而实现高效可靠的运行。
One perspective to consider when discussing the blade edge pillar lock principle is its role in promoting safety and stability. 当讨论叶片边柱锁原理时，需要考虑的一个视角是它在促进安全和稳定性方面的作用。
The proper functioning of this mechanism is crucial in preventing potential accidents and ensuring the smooth operation of equipment such as wind turbines, aircraft propellers, and industrial fans. 这种机制的正常运行对于防止潜在事故，并确保风力涡轮机、飞机螺旋桨和工业风扇等设备的平稳运行至关重要。
From a technical standpoint, the blade edge pillar lock principle involves the use of specialized fastening devices and mechanisms that are designed to withstand high levels of stress and ensure atight and secure connection. 从技术角度来看，叶片边柱锁原理涉及使用专门的紧固装置和机制，旨在承受高水平的应力，并确保紧密牢固的连接。
激发三重态（Excitedthreestates）
激发三重态（Excited three states）At most temperatures, most molecules are at the lowest vibrational level of the ground state. Molecules absorbed in the ground state absorb energy (electric energy, thermal energy, chemical energy, or light energy, etc.) and are excited to be excited. The excited state is very unstable,It will release energy quickly and re jump back to the ground state. When the molecules return to the ground state, the energy is emitted in the form of emission of electromagnetic radiation (light), known as luminescence". If the molecules of matter absorb light energy, they are stimulatedThe electromagnetic radiation emitted by the transition back to the ground state, known as fluorescence and phosphorescence. The mechanism of fluorescence and phosphorescence is discussed in terms of molecular structure theory.Each molecule has a series of strictly separated energy levels, called electron energy poles, and each electron energy level contains a series of vibrational energy levels and rotational energy levels. The state of motion of electrons in moleculesIn addition to the energy levels, the electrons contain multiple states of electrons. In M=2S+1, S is the sum of the quantum numbers of each electron spin quantum, with a value of 0 or 1. According to the principle of Pauli incompatibility, the same orbital in the moleculeThe two electrons occupied must have opposite spin directions, namely spin pairing. If all electrons in the molecule are spinpaired, then S=0, M=1, the molecule is in a singlet state (or a single line), expressed in symbolic S.The ground states of most organic compounds are in the singlet state. When the ground state molecules absorb energy, if the electron does not change in the direction of spin during the transition, it is still M=1, and the molecules are excited at a single weightIf the electron is accompanied by a change in the spin direction during the transition, then the molecule has two spin unpaired electrons, S=1, M=3, and the molecule is in the excited three state, expressed in symbolic T.Fig. 14.1 is a schematic diagram of electronic states.Fig. 14.1 sketch of excitation of three heavy states in a singlet stateThe unpaired electrons in discrete orbits are more stable than spin pairs (especially the rules), so in the same excited state, the energy levels of the three states are always slightly lower than those of the singlet state.Fig. 14.2 is a diagram of energy levels and transitions, in which S0, S1 and S2 represent the ground states of the molecules, the first and second electron excited singlet states, respectively, and T1 and T2 represent the three and second electron excited states of the molecule respectively. V=0, 1, 2, 3,... Represents the vibrational level of theground state and excited state.Fig. 14.2 energy level diagram of fluorescence and phosphorescence systemThe molecules in the excited state are very unstable, which may be activated by means of radiative transitions and nonradiative transitions (de excitation), releasing excess energy and returning to the ground state.Radiation transitions are mainly related to fluorescence, delayed fluorescence or phosphorescence emission; nonradiative transition is the release of excess energy in the form of heat, including vibrational relaxation, internal transfer, intersystem crossing and external transferCheng. Fig. 14.2 represents the energy transfer process of molecular excitation and deactivation:(1) vibrational relaxation (Vibration, relaxation, abbreviated as VR) - the transition from the lowest vibrational energy level (V=0) of the ground state to the excited singlet state may be possible when the molecules absorb the radiation of light (as shown in lambda 1, lambda 2 in Fig. 14.2)Higher vibrational levels of Sn (as shown in S1 and S2). Then，In the gas phase where the liquid phase or the pressure is high enough, the collision probability between molecules is large, and the molecules may pass excess vibrational energy to the surrounding region in the form of heatEnvironment, and its transition from the high vibrational energy level of the excited state to the lowest vibrational level of the electron energy level, this process is called vibrational relaxation. The vibrational relaxation time is 10 - 12s orders of magnitude.(2) internal transfer (Internal, conversion, abbreviated as IC) - when the low vibrational energy levels in the high electron levels overlap with the high vibrational energy levels in the lower electron levels, electrons frequently occur from the high electron energy levelsThe transition from nonradiative to low electron levels. As shown in Fig. 14. and 2, the low vibrational kinetic energy levels in S2 and T2 overlap with the high vibrational kinetic energy levels in S1 and T1, and electrons can transition from S2 to S1 through the superposition of vibrational levels, or fromT2 transition to T1. This process is called internal transfer. Time transfer for 1011s ~ 1013s magnitude. The rate of vibrational relaxation and internal transfer is much faster than the direct emission of photons by a highly excited state,Therefore, no matter which excited singlet state excited by the radiation energy, the molecules can jump to the lowest vibrational level via vibrational relaxation and internal transfer to the lowest (first) excited singlet state.(3) fluorescence emission (Fluorescence, emission, FE) - afterthe vibrational relaxation and internal transfer of electrons in the excited singlet state, reach the lowest vibrational level (V=0) of the first excited singlet (S1),The vibrational levels of the ground state (S0) transition in the form of radiation. The process is fluorescence emission with a fluorescence wavelength of. The energy loss due to vibrational relaxation and internal transfer, and hence the fluorescence emission energyThe energy is smaller than the molecular absorption, and the wavelength of fluorescence emission is longer than the wavelength of molecular absorption. The average lifetime of the lowest vibrational level in the first excited singlet state is about 10-9 - 10 - 4S, so the fluorescence lifetime is also in the rangeThis order of magnitude.(4) department (Intersystem Crossing, ISC Kuayue) - between leap refers to the non radiative transition process between different multiplets, it relates to the electronic excited spin state change.Such as the transition from the first excited singlet state S1 to the first excited three heavy state T1, so that the two spin pairs of electrons are no longer paired. This transition is prohibited (not in conformity with the spectral selection rule),But if the two energy layers have a large overlap, the minimumvibrational level of S1 in Figure 14.2 overlaps with the higher vibrational levels of T1, and it is possible to achieve this transition by spin orbit coupling.Between leap slower and experience a long time.(5) (Phosphorescence emission, PE luminescence emission) - the electronic excited state by the Department after three leap reach the excited state, after the rapid relaxation of vibrational relaxation and the transition to the first excited state threeThe lowest vibrational energy levels are then converted in the form of radiation back to the vibrational levels of the ground state, which are emitted by phosphorescence. The transition of the phosphorescence emission is still the spin forbidden, so the light speed is very slow.The life of 10-4 ~ 100s phosphor. Therefore, after the external light source is stopped, phosphorescence remains a short time. After the system vibration leap and T1 lost a part of the energy relaxation,So the phosphorescence wavelength is longer than the fluorescence wavelength, that is, the wavelength is longer than the wavelength of the phosphor.It must be pointed out that T1 may also be re excited by thermal excitation back to S1, i.e., T1S1, and then converted back to S0 by radiation from S1, S1S0, which emits fluorescence, which is called delayed fluorescence,Its lifetime is similar to that of phosphorescence, but its wavelength is shorter than phosphorescence.(6) external transfer (External, convertion, EC) - excited state molecules collide with solvent molecules or other solute molecules, and the process of energy transfer is called external transfer.External transfer can weaken or even weaken the intensity of fluorescence or phosphorescence. This phenomenon is called quenching or quenching.。
The power of the wave Wave energy storage
The power of the wave Wave energystorageWave energy has long been recognized as a potential source of renewable energy. The power of the ocean's waves has the capacity to generate large amounts of electricity, making it an attractive option for countries looking to reduce their reliance on fossil fuels. However, one of the major challenges with wave energy is the issue of storage. Unlike traditional sources of energy such as coal or natural gas, wave energy is not consistently available, making it difficult to harness and store for later use. In this response, we will explore the potential solutions for wave energy storage and the implications for the future of renewable energy. One potential solution for wave energy storage is the use of hydroelectric pumped storage. This method involves using excess wave energy to pump water from a lower reservoir to a higher reservoir, where it can be stored until needed. When electricity demand is high, the water is released from the higher reservoir, flowing through turbines to generate electricity. This method has beensuccessfully used with other forms of renewable energy, such as solar and wind power, and could potentially be adapted for wave energy storage as well. However, the feasibility of this method for wave energy storage depends on the availability of suitable locations for reservoirs and the environmental impact of constructing and operating such facilities. Another potential solution for wave energy storage is the use of large-scale batteries. Advances in battery technology have made it increasingly feasible to store large amounts of energy for later use. By capturing excess wave energy and storing it in batteries, it could be released when demandis high, providing a more consistent and reliable source of electricity. However, the cost and environmental impact of manufacturing and disposing of large-scale batteries are significant considerations that must be taken into account. In addition to these technical solutions, it is also important to consider the social and economic implications of wave energy storage. The development and implementation of wave energy storage technologies have the potential to create new jobs and stimulate economic growth in the renewable energy sector. However, it is also important to consider the potential impact on local communities and theenvironment. The construction and operation of wave energy storage facilities could have significant environmental impacts, such as changes to marine ecosystems and coastal landscapes. It is essential to carefully consider these potential impacts and involve local communities in the decision-making process to ensurethat wave energy storage is implemented in a sustainable and responsible manner. Furthermore, the development of wave energy storage technologies has the potential to contribute to global efforts to combat climate change. By harnessing the power of the ocean's waves and storing it for later use, we can reduce our reliance on fossil fuels and decrease greenhouse gas emissions. This has the potential to mitigate the impacts of climate change and create a more sustainable future for generations to come. However, it is important to recognize that wave energy storage is just one piece of the puzzle in transitioning to a more sustainable energy system. It must be integrated with other forms of renewable energy and energy efficiency measures to truly make a meaningful impact on reducing carbon emissions. In conclusion, wave energy storage presents both opportunities and challenges for the future of renewable energy. While there are potential technical solutions, such as hydroelectric pumped storage and large-scale batteries, it is important to consider the broader social, economic, and environmental implications of implementing these technologies. By carefully considering these factors and involving local communities in the decision-making process, we can work towards a more sustainable and responsible approach to wave energy storage. Ultimately, the development of wave energy storage technologies has the potential to contribute to a more sustainable and resilient energy system, reducing our reliance on fossil fuels and mitigating the impacts of climate change.。
Optimal values of rovibronic energy levels for triplet electronic states of molecular deute
∗
Electronic address: lavrov@pobox.spbu.ru
2
I. INTRODUCTION
The present work is devoted to the studies of the wavenumbers of the triplet-triplet radiative electronic-vibro-rotational (rovibronic) transitions and empirical determination of the optimal set of the triplet rovibronic energy levels of the D2 molecule. Studies of spectra and structure of molecular deuterium represent not only understandable general interest (an isotopomer of simplest neutral diatomic molecule), but have also direct practical value in connection with wide use of D2 in physical experiments and in various technical applications: from gas-discharge sources of ultraviolet radiation [1] up to tokamak-reactors [2]. The spectrum of the D2 molecule is caused by both singlet-singlet and triplet-triplet rovibronic transitions. The intercombination lines were not observed yet. The most interesting resonance singlet band systems are located in vacuum ultraviolet (VUV), while the triplet transitions are responsible for major part of light emission of ionized gases and plasma in near infrared, visible and near ultraviolet. They are often used for spectroscopic diagnostics of non-equilibrium plasmas [1, 2, 3, 4, 5, 6]. Therefore, the triplet rovibronic levels and optical transitions between them were chosen as the object of the present research. The energy level values evaluated from experimental wavenumbers are often called observed energy levels irrespective of a method used for the data processing. Such rather disputable terminology implicitly assumes that all spurious experimental results and systematic errors are absent, and random errors are negligibly small (Otherwise, several different sets of the observed energy level values may be obtained from the same set of experimental wavenumbers by applying different methods of the data processing.). Therefore, we prefer to use the term empirical level values
绝热电离能英文
绝热电离能英文What is adiabatic ionization energy?Adiabatic ionization energy refers to the minimum amount of energy needed to remove an electron from a neutral atom or molecule in its ground state, resulting in the formation of a positively charged ion. This process is also known as ionization or ionization potential.What are the factors that affect adiabatic ionization energy?Several factors affect the adiabatic ionization energyof an atom or molecule, including:1. Nuclear charge: The greater the nuclear charge, the stronger the attraction between the electrons and the nucleus, making it more difficult to remove an electron and increasing the ionization energy.2. Atomic or molecular size: The larger the size of the atom or molecule, the farther the outermost electron is from the nucleus, making it easier to remove, resulting in a lower ionization energy.3. Electron shielding: The more electrons there are between the outermost electron and the nucleus, the weaker the attraction between them, resulting in a lowerionization energy.4. Electron configuration: The arrangement of electrons in the atom or molecule can affect the ionization energy, as removing an electron from a filled shell is moredifficult than removing one from a partially filled shell.What is the difference between adiabatic and vertical ionization energy?Adiabatic and vertical ionization energy are two typesof ionization energy. Adiabatic ionization energy refers to the energy required to remove an electron from a neutral atom or molecule in its ground state, while vertical ionization energy refers to the energy required to remove an electron from an excited state of the atom or molecule.The main difference between the two is that adiabatic ionization energy takes into account the energy released or absorbed by the system during the ionization process, while vertical ionization energy does not.What is the significance of adiabatic ionization energy?Adiabatic ionization energy is a fundamental property of atoms and molecules and is useful in understanding their chemical and physical properties. It can be used to predict the reactivity of atoms and molecules in chemical reactions, as well as their electronic structure and bonding behavior.In addition, adiabatic ionization energy is an important tool in analytical chemistry, as it can be used to identify and quantify the presence of certain elements or moleculesin a sample.绝热电离能是什么？绝热电离能是指从一个处于基态的中性原子或分子中去除一个电子所需要的最小能量，从而形成带正电的离子。
yale--chemistry
Dates and DeadlinesPlease note that all deadlines are subject to change at any time. Summer-Fall 2010.Applicants should take respective GRE, GRE Subject,TOEFL, and IELTS exams no later than November (required exams) in order to guarantee that official scores reach the Graduate School by the application deadline for the department to which you are applying.Mid-August 2010. Application becomes available online for Fall 2011 admission.December 3, 2010 .Deadline for Biological and Biomedical Sciences (BBS). All supplemental materials and official standardized test scores must be received by this date to be considered by Yale for Fall 2011 admission.December 15, 2010. Deadline for Ecology and Evolutionary Biology, Economics, Epidemiology and Public Health, History, Political Science, Psychology and Urban Education. All supplemental materials and official standardized test scores must be received by this date to be considered by Yale for Fall 2011 admission.January 2, 2011.Deadline for all other departments. All supplemental materials and official standardized test scores should be received to be considered by Yale for Fall 2011 admission. Applications cannot be submitted after this date.January-March 2011. Applications for fall 2011 reviewed by departments and programs.February-March 2011. Official admissions decisions for fall 2011 communicated to applicants.April 15, 2011.Deadline for applicant responses to most offers of admission for fall 2011.ChemistryPh.D.Please see the Graduate School’s Programs and Policies bulletin for a listing of administrators, faculty, fields of study, admissions requirements, degree requirements, combined and joint degree opportunities, and course offerings in this program.The program’s web pages provide contact information and fields of specialty for the Director of Graduate Studies, faculty and current graduate students.CHEMISTRYSterling Chemistry Laboratory, 203.432.3913M.S., Ph.D.ChairScott Miller (1 SCL, 203.432.3912, chemistry.chair@)Director of Graduate StudiesJ. Patrick Loria (1 SCL, 203.432.3913, chemistry.dgs@)Professors Sidney Altman (Molecular, Cellular & Developmental Biology), Victor Batista, Jerome Berson (Emeritus), Gary Brudvig, Robert Crabtree, Craig Crews (Molecular, Cellular & Developmental Biology), R. James Cross, Jr., Donald Crothers (Emeritus), John Faller, Gary Haller (Engineering & Applied Science), Francesco Iachello (Physics), Mark Johnson, William Jorgensen, J. Patrick Loria, J. Michael McBride, Scott Miller, Peter Moore, Lynne Regan (Molecular Biophysics & Biochemistry), James Rothman (Cell Biology), Martin Saunders, Alanna Schepartz, Charles Schmuttenmaer, Dieter Söll (Molecular Biophysics & Biochemistry), Thomas Steitz (Molecular Biophysics & Biochemistry), Scott Strobel (Molecular Biophysics & Biochemistry), John Tully, Patrick Vaccaro, Harry Wasserman (Emeritus), Kenneth Wiberg (Emeritus), Frederick Ziegler (Emeritus), Kurt ZilmAssociate Professor Ann ValentineAssistant Professors Nilay Hazari, Seth Herzon, David Spiegel, Elsa YanFields of StudyFields include bio-inorganic chemistry, bio-organic chemistry, biophysical chemistry, chemical physics, inorganic chemistry, organic chemistry, physical chemistry, physical-organic chemistry, synthetic-organic chemistry, and theoretical chemistry.Special Admissions RequirementsApplicants are expected to have completed or be completing a standard undergraduate chemistry major including a year of elementary organic chemistry, with laboratory, and a year of elementary physical chemistry. Other majors are acceptable if the above requirements are met. The GRE General Test andthe Subject Test in Chemistry are required. Students whose native language is not English are required to take the Test of English as a Foreign Language (TOEFL) and the Test of Spoken English (TSE) if the TOEFL Internet-based test is not taken.Special Requirements for the Ph.D. DegreeA foreign language is not required. Three term courses are required in each of the first two terms of residence, and participation in additional courses is encouraged in subsequent terms. Courses are chosen according to the student’s background and research area. To be admitted to candidacy a student must (1) receive at least two term grades of Honors, exclusive of those for research; (2) pass either three cumulative examinations and one oral examination (organic students) or two oral examinations (nonorganic students) by the end of the second year of study; and (3) submit a thesis prospectus no later than the end of the third year of study. Remaining degree requirements include completing eight cumulative examinations (organic students), a written thesis describing the research, and an oral defense of the thesis. The ability to communicate scientific knowledge to others outside the specialized area is crucial to any career in chemistry. Therefore, all students are required to teach a minimum of two terms at the level of Teaching Fellow 3 or higher.Master’s DegreeM.S. (en route to the Ph.D.)A student must pass at least five graduate-level term courses in the Chemistry department exclusive of seminars and research. In addition, an overall average (exclusive of seminars and research) of High Pass must be maintained in all courses. One full year of residence is required.Program materials are available upon request to the Director of Graduate Studies, Department of Chemistry, Yale University, PO Box 208107, New Haven CT 06520-8107.CoursesCHEM 505a, Alternative Energy Robert Crabtree, Gary Brudvig, Charles Schmuttenmaer, Victor BatistaTeam-taught. Design principles for molecular components of alternative energy devices. Light energy conversion, energy transfer and charge separation in photosynthesis. Dioxygen evolution in photosystem II. Biofuels. Bioethanol, biodiesel, hydrogenase. Interaction of light with semiconductors. Fast spectroscopy to probe interfacial electron transfer. Computational design and characterization. Solar cells for electricity, photocatalysis, biomimetic water oxidation. Hydrogen economy. No final exam—paper instead. TTH 10:30–11:45CHEM 518a u, Advanced Organic Chemistry William JorgensenConcise overview of structure, properties, thermodynamics, kinetics, reactions, and intermolecular interactions for organic molecular systems. MW 11:35–12:50CHEM 519b, Advanced Organic Chemistry II Scott MillerContinuation of CHEM 518a. Concise overview of structure, properties, thermodynamics, kinetics, reactions, and intermolecular interactions for organic molecular systems. Particular emphasis on stereochemical aspects of chemical reactions of interest to synthetic settings as well as in biomolecules. MW 11:35–12:50CHEM 521b u, Chemical Biology Alanna SchepartzA one-term introduction to the origins and emerging frontiers of chemical biology. Discussion of the key molecular building blocks of biological systems and the history of macromolecular research in chemistry. TTH 9–10:15CHEM 523a u, Synthetic Methods in Organic Chemistry Seth HerzonA discussion of modern methods. Functional group manipulation, synthesis and functionalization of stereodefined double bonds, carbonyl addition chemistry, and synthetic designs. Normally taken only by students with a special interest in organic synthesis; for others, CHEM 518a is more appropriate. MWF 10:30–11:20CHEM 524b, Advanced Synthetic Methods in Chemistry Seth HerzonSelected topics in organic synthesis. Strategies for the synthesis of complex, biologically active molecules, including retrosynthetic analysis. Considerable emphasis is placed on strategy-level reactions, asymmetric catalysis, and applications to targets. Reaction mechanisms are emphasized throughout the course. MWF 8:20–9:10[CHEM 525b u, Spectroscopic Methods of Structure Determination][CHEM 526b u, Computational Chemistry and Biochemistry][CHEM 528a, Natural Product Synthesis]CHEM 530b u, Statistical Methods and Thermodynamics Victor BatistaThe fundamentals of statistical mechanics developed and used to elucidate gas phase and condensed phase behavior, as well as to establish a microscopic derivation of the postulates of thermodynamics. Topics include ensembles; Fermi, Bose, and Boltzmann statistics; density matrices; mean field theories; phase transitions; chemical reaction dynamics; time-correlation functions; Monte Carlo and molecular dynamics simulations. MWF 9:25–10:15[CHEM 535a, Chemical Dynamics]CHEM 540a u, Molecules and Radiation I Kurt ZilmAn integrated treatment of quantum mechanics and modern spectroscopy. Basic wave and matrixmechanics, perturbation theory, angular momentum, group theory, time-dependent quantum mechanics, selection rules, coherent evolution in two-level systems, line shapes, and NMR spectroscopy. MWF 8:20–9:10CHEM 542b u, Molecules and Radiation II Charles SchmuttenmaerAn extension of the material covered in CHEM 540a to atomic and molecular spectroscopy, including rotational, vibrational, and electronic spectroscopy, as well as an introduction to laser spectroscopy. MW 11:35–12:50CHEM 547b, Electron Paramagnetic Resonance Gary BrudvigA quantum mechanical treatment of magnetic resonance aimed at providing an understanding of the fundamentals of EPR spectroscopy. Topics include solutions and solid-state measurements of radicals and spin labels, triplet states, transition metals, pulsed and double-resonance methods, and applications to biological systems. MWF 10:30–11:20[CHEM 548b, Nuclear Magnetic Resonance in Liquids][CHEM 549b u, Biophysical Chemistry]CHEM 550b u, Theoretical and Inorganic Chemistry Nilay HazariElementary group theory, molecular orbitals, states arising from molecular orbitals containing several electrons, ligand field theory, and electronic structure of metal complexes. Introduction to physical methods used in the determination of molecular structure and the bonding of polyatomic molecules. TTH 9–10:15CHEM 552a u, Organometallic Chemistry Nilay HazariA survey of the organometallic chemistry of the transition elements and of homogeneous catalysis. TTH 9–10:15CHEM 554b, Bio-Inorganic Chemistry Ann ValentineAn advanced introduction to biological inorganic chemistry. Important topics in metalloprotein chemistry are illustrated. Objective is to define and understand function in terms of structure. Topics include catalysis with and without electron transfer, and carbon, oxygen, and nitrogen metabolism. MWF 8:20–9:10[CHEM 555b, Inorganic Mechanisms]CHEM 556a, Biochemical Rates and Mechanisms J. Patrick LoriaAn advanced treatment of enzymology. Topics include transition state theory and derivation of steady-state and pre-steady-state rate equations. The role of entropy and enthalpy in acceleratingchemical reactions is considered, along with modern methods for the study of enzyme chemistry. These topics are supplemented with in-depth analysis of the primary literature. MWF 9:25–10:15CHEM 557a u, Modern Coordination Chemistry John FallerThe principles of modern inorganic chemistry. Main group and transition element chemistry: reactions, bonding, structure, and spectra. TTH 11:35–12:50[CHEM 558b, Biophysical Spectroscopy]CHEM 560La, Advanced Physical Methods in Molecular Science I Patrick VaccaroA laboratory course introducing physical chemistry tools used in the experimental and theoretical investigation of large and small molecules. Modules include electronics, vacuum technology, optical spectroscopy and lasers, and computer programming. F 3–4CHEM 560Lb, Advanced Physical Methods in Molecular Science II R. James Cross, Jr.A laboratory course introducing physical chemistry tools used in the experimental and theoretical investigation of large and small molecules. Modules include machining materials, magnetic resonance, optical spectroscopy and lasers, and computational tools. F 3–4CHEM 562L, Laboratory in Instrument Design and the Mechanical Arts Kurt Zilm, David JohnsonFamiliarization with modern machine shop practices and techniques. Use of basic metalworking machinery and instruction in techniques of precision measurement and properties of commonly used metals, alloys, and plastics.CHEM 564L, Advanced Mechanical Instrumentation Kurt Zilm, David JohnsonA course geared for both the arts and sciences that goes beyond the basic introductory shop courses, offering an in-depth foundation study utilizing hands-on instructional techniques that must be learned from experience. Prerequisite: CHEM 562L.CHEM 565L, Introduction to Glass Blowing Patrick Vaccaro, Daryl SmithThe course provides a basic introduction to the fabrication of scientific apparatus from glass. Topics covered include laboratory setup, the fundamental skills and techniques of glass blowing, the operation of glass fabrication equipment, and requisite safety procedures.CHEM 570a u, Introductory Quantum Chemistry Victor BatistaThe elements of quantum mechanics developed and illustrated with applications to chemical problems. Suitable for first-year graduate students in chemistry who have had some exposure to quantum mechanics as part of an undergraduate chemistry course. TTH 9–10:15CHEM 572a, Advanced Quantum Mechanics John TullyTopics in quantum mechanics that are essential for understanding modern chemistry, physics, and biophysics. Topics include the interaction of radiation with matter and using quantized radiation fields, and may include time-dependent quantum theory, scattering, semiclassical methods, angular momentum, density matrices, and electronic structure methods. Prerequisite: CHEM 570a or equivalent. TTH 9–10:15CHEM 590a,b, Ethical Conduct and Scientific Research Jonathan ParrA survey of ethical questions relevant to the conduct of research in the sciences with particular emphasis on chemistry. A variety of issues, including plagiarism, the falsification of data, and financial malfeasance, will be discussed, using as examples recent cases of misconduct by scientists. Enrollment is restricted to graduate students in chemistry. HTBACHEM 600–670, Research Seminars FacultyPresentation of a student’s research results to his/her adviser and fellow research group members. Extensive discussion and literature review are normally a part of the series.CHEM 700, Laboratory Rotation for First-Year Biophysical and Chemical Biology Graduate Students Gary Brudvig, Craig CrewsCHEM 720, Current Topics in Organic Chemistry FacultyA seminar series based on invited speakers in the general area of organic chemistry.CHEM 730, Molecular Science Seminar FacultyA seminar series based on invited speakers in the areas of physical, inorganic, and biological chemistry.CHEM 990, Research FacultyIndividual research for Ph.D. degree candidates in the Department of Chemistry, under the direct supervision of one or more faculty members.Return to TopThe GRE subject test is required. Applications lacking a GRE test score will not be evaluated.。
振动力英语
振动力英语Vibration is a fundamental concept in physics that describes the oscillatory motion of an object around an equilibrium point. It is a common phenomenon in the natural world, from the humming of a bee's wings to the rumbling ofan earthquake. In the context of engineering and technology, understanding and controlling vibration is crucial for the performance and longevity of machinery and structures.Vibration can be categorized into two main types: freeand forced. Free vibration occurs when an object oscillates without any external force, driven by its own internal energy. An example of this is a weight on a spring that oscillates back and forth until its energy is dissipated through damping. On the other hand, forced vibration happens when an external force continuously applies energy to the system, causing itto oscillate at a frequency that matches the frequency of the external force.The study of vibration is essential in various industries. In automotive engineering, for instance, engineers mustdesign suspension systems that minimize vibrations to ensurea smooth ride and to protect the vehicle's components from damage. In aerospace, the vibrations of aircraft wings mustbe carefully managed to prevent structural fatigue andfailure.Controlling vibration can be achieved through severalmethods. One common approach is to use damping materials that absorb the energy of the vibrations, reducing their amplitude. Another method is to employ active or passive vibration isolation systems that separate the source of the vibration from the structure that needs to be protected.Moreover, vibration analysis is a powerful diagnostic tool. By monitoring the vibrations in machinery, engineerscan detect signs of wear or malfunction before they lead to failure. This predictive maintenance approach can save significant time and resources by preventing unexpected breakdowns.In conclusion, the study and control of vibration arevital in many areas of science and engineering. From ensuring the stability of bridges to improving the efficiency of engines, understanding the principles of vibration allows usto create safer, more reliable, and more durable systems.。
外文翻译----降低汽车噪声的方法
Ways to reduce vehicle noiseWith the rapid development of automobile industry, there is comfort and vehicle vibration and noise control of more and more stringent requirements. According to relevant data shows that 70 percent of the city noise from the traffic noise, and traffic noise is mainly car noise. It is seriously polluting the urban environment, affecting people's life, work and health. So noise control is not only related to comfort, but also related to environmental protection. However, all also from the vibration noise, vibration can cause certain parts of the early fatigue damage, thereby reducing the service life of motor vehicles; excessive noise can damage hearing the driver will enable the rapid driver fatigue, thus driving security constitutes a grave threat. So noise control, is also related to motor vehicle durability and safety. Thus vibration, noise and comfort are the three closely related, it is necessary to reduce vibration, reduce noise, but also improve ride comfort, and ensure the product economy, vehicle noise control in the standard range.One type of noise arising from car noise are the main factors of air power, mechanical drive, the electromagnetic three parts. From the structure can be divided into the engine (ie, combustion noise), the chassis noise (ie, power train noise, all components connected with the noise), electrical equipment, noise (cooling fan noise, car noise generator), body noise (such as body structure, shape and attachment installation unreasonable noise). One of the engine noise accounted for more than half of motor vehicle noise, including noise and body intake noise (such as engine vibration, the rotational axis Valve, Jin, door switches, such as exhaust noise). Therefore the engine vibration, noise reduction has become a key automotive noise control.noise requirements of regulations in Europe, from October 1996 onwards, the external bus 77dBA noise must be reduced to 74dBA, noise was reduced by half energy, the end of the century further reduced to 71dBA. Japan's laws and regulations, small car in the next decade to control noise standards at the following 76dBA. A number of domestic cities are also planning to traffic trunk lines in 2010 to control noise at the average of less than 70dBA. According to the domestic current data indicate that the domestic value of bus noise permit shall not exceed 82dBA, light trucks for 83.5dBA. This shows that our country in the vehicle noise control will have to make do.noise assessment noise evaluation mainly refers to the car, outside noise and vibration adaptive value. Evaluation methods can be divided into subjective evaluation and objective evaluation. Subjective assessment of the impact of vehicle noise is a major factor in comfort, loudness and uncertainties, such as semantic differential method can be used for subjectiveevaluation. At an objective evaluation, can be used PCNM noise measuring device for measuring test analysis; addition simulation technology in the finite element method (FEM) and boundary element method (BEM) has been widely applied.noise control noise generation and dissemination in accordance with the mechanism of noise control technology can be put into the following three categories: First, the control of noise sources, are two routes of transmission of noise control, noise three recipients are protected. One of the control of noise sources are the most fundamental, the most direct measures, including noise reduction to reduce the exciting force and the engine parts of the exciting force response, which means transformation of acoustic source local oscillator. However, it is difficult to control noise sources when necessary in the route of transmission of noise to take measures, such as sound absorption, sound insulation, noise reduction, vibration and vibration isolation measures. Motor vehicles and vehicle vibration and noise reduction level of power, economy, reliability and strength, stiffness, quality, manufacturing costs and use are closely related.engine to reduce vibration and noise of the engine noise is the focus of automotive noise control. Engine vibration and noise are generated at source. Engine noise is from fuel combustion, valve bodies, gears and piston timing noise percussion synthesis.(1) ontology engine noiseLower engine noise will be ontological transformation of local oscillator sound sources, including methods such as finite element method analysis and design engines, selection of soft combustion process, improve the structure of the body stiffness, with the use of tight space, reduce noise cylinder cover. In addition, give the engine Tu damping material is an effective approach. Damping materials can kinetic energy into thermal energy. To deal with the principle of damping is a damping materials and components into its vibrational energy to consume. It has the following structure: Freedom damping layer structure, and spacing of freely damping layer structure, and constrained damping layer structure and spacing of constrained damping layer. It is clear that the adoption of a decrease of resonance amplitude and accelerated the decay of free vibration, reducing the various parts of the Chuan-Zhen capacity, an increase of parts at or above the critical frequency of vibration isolation capacity. At present, some countries have designed an engine experts active vibration isolation system to reduce engine vibration, in order to achieve the purpose of noise reduction.(2) intake noiseEngine intake noise is one of the main noise source, the Department of the engine noise ofair power, with the engine speed increases to strengthen. Non-supercharged engine intake noise major components, including the cyclical pressure fluctuation noise, vortex noise, the cylinder of the Helmholtz resonance noise. Diesel engine supercharger intake noise mainly from the turbocharger compressor. Two stroke engine noise from the Roots pump. In this regard, the most effective method is the use of intake muffler. There is a resistive type muffler (absorption type), resistant muffler (expansion type, resonance type, interference-type and porous decentralized) and the composite muffler. To combine with the air filter (that is in the air filter on an additional resonance chamber and sound-absorbing material, for example, type R3238) has become the most effective intake muffler, muffler volume of more than 20dBA.Chassis Noise(1) Department of exhaust noiseDepartment of the chassis exhaust noise is the main noise sources, mainly from the exhaust pressure pulsation noise, air flow through the valve seat when issued by eddy current noise, because of boundary layer airflow disturbance caused by noise and exhaust Office jet noise composition.(2) power train noisePowertrain noise from the vibration caused by change gear meshing and rotating shaft vibration. General measures taken are: First, choose low-noise transmission, engine and gearbox are two and the main reducer, such as rear axle and chassis components for flexible rubber pad connections, so as to achieve the purpose of isolation; are three-axis rotational control balance degrees, to reduce torsional vibration.Electric equipment noise(1) cooling fan noiseCooling fan noise happened devices are subject to wind retaining ring, water pump, radiator and transmission, but the noise generated depends primarily on the chassis.(2) automobile generator noiseAutomotive generator noise depends on the effects of a variety of sources, these sources have magnet source, mechanical and air power source. Noise level depends on the generator magnetic structure and ventilation systems, as well as generators precision manufacturing and assembly.Body NoiseAs the speed increased, the body will be more and more noise, and air power are the main causes of noise. Therefore, the following programs to improve the body noise: First, to streamline the design of the body, achieve a smooth transition;second are in between the body and frame components to adopt a flexible connection; third，interior is softened, such as Inner Mongolia at the roof and body skin the use of sound-absorbing material.In addition, the car at high speed when the tire is also a source of noise. Tire Tread greater, then the greater the noise. In addition, the tire tread with the noise generated also have a great relationship, there is a reasonable choice of the pattern of steel cord for radial tires to reduce tire noise are an effective way. Materials for the tire, the use of more flexible and soft rubber with high, you can create a low-noise tires.Other measuresAutomobile noise control, except in the design on the use of optimization methods and optimization of selected components, it can also carry out active control of noise. This is based on sound muffler technology, the principle is: the use of electronic muffler system with the opposite phase of the acoustic noise, vibration so that the two cancel each other out in order to reduce the noise. This muffler device used extremely advanced electronic components, has excellent noise reduction effect can be used to reduce vehicle noise, engine noise, the engine could also be used to proactively support systems, to offset the engine vibration and noise.降低汽车噪声的方法随着汽车工业的迅猛发展，对车辆的舒适性,缓震性和噪声有了越来越严格的要求。
柔性联轴器(盖茨)
- High vibration damping. Damping increases with load, which will prevent resonance. - Low noise levels and quiet in operation. - Zero backlash and, consequently, high positioning accuracy. - Easy to install and to replace. Can be inspected without stopping the drive. - Built-in safety measure: the driven machine will stop when the coupling fails. - High tolerance of combinations of radial and angular misalignment. - Durable. - Low inertia. - Compact design. - Light weight.
(1) Patent applied for
2
EUROGRIP® COUPLINGS FEATURES & BENEFITS AT A GLANCE
Gates EuroGrip® flexible couplings were tested by the Institut für Maschinenelemente der RWTH-Aachen. The following table highlights the features and design opportunities of Gates EuroGrip® flexible couplings.
gruneisen参数算弛豫时间 -回复
gruneisen参数算弛豫时间-回复Gruneisen parameter is a fundamental parameter used to describe the thermal properties of materials. In this article, we will explore the concept of the Gruneisen parameter and its relation to relaxation time.Firstly, let's start by understanding the Gruneisen parameter. Named after the German physicist Eduard Grüneisen, this parameter is defined as the derivative of the thermal expansion coefficient with respect to volume or the negative derivative of the bulk modulus with respect to pressure at constant temperature. In simpler terms, it represents the relationship between the volume change and the temperature change for a material.The Gruneisen parameter is often denoted as γor γ(T), where T represents temperature. It quantifies the anharmonicity in the lattice vibrations of a material and provides valuable insights into the thermal properties of solids, such as phonon behavior and thermal transport. It is an important factor in understanding materials' response to thermal expansion and contraction.Now, let's move on to the concept of relaxation time. Relaxationtime is a measure of how long it takes for a system to return to its equilibrium state after being perturbed. In terms of thermal properties, relaxation time refers to the time it takes for the lattice vibrations to reach thermal equilibrium after the application of a temperature change.The relation between the Gruneisen parameter and relaxation time can be understood through the Debye model of lattice vibrations. According to the Debye model, lattice vibrations in solids can be treated as phonons, which are quantized units of vibrational energy. These phonons can be thought of as waves propagating through the lattice.In the Debye model, the relationship between the Gruneisen parameter, γ, and the relaxation time, τ, can be expressed as follows:γ(T) = (V/V0) * (dT/dV) * (V0/CV) * τIn this equation, V represents volume, V0 represents the equilibrium volume, dT/dV represents the pressure derivative of the temperature change, CV represents the heat capacity atconstant volume, and τrepresents the relaxation time.From this equation, we can see that the Gruneisen parameter and relaxation time are related through the factors involving volume, temperature change, pressure derivative, and heat capacity. The relaxation time is inversely proportional to the Gruneisen parameter, indicating that a larger Gruneisen parameter corresponds to a shorter relaxation time.The Gruneisen parameter itself is influenced by various factors, including interatomic interactions, lattice structure, and vibrational modes. It varies with temperature and can exhibit different values for different materials. In materials with higher thermal conductivity, the Gruneisen parameter tends to be smaller, indicating a longer relaxation time. Conversely, in materials with lower thermal conductivity, the Gruneisen parameter tends to be larger, indicating a shorter relaxation time.In conclusion, the Gruneisen parameter provides valuable information about the thermal properties of materials, particularly their response to temperature changes. It is related to therelaxation time, which measures how long it takes for a material to return to thermal equilibrium. By understanding the relationship between the Gruneisen parameter and relaxation time, researchers can gain insights into the thermal behavior of materials and make informed decisions regarding their applications in various industries.。
纸和尺子的小实验英语作文
纸和尺子的小实验英语作文Paper and Ruler: A Tale of Physics and Imagination.In the annals of scientific exploration, simple tools often yield profound insights into the intricate workings of the universe. A paper and a ruler, seemingly mundane objects, serve as a testament to this fact, unlocking a realm of captivating experiments that reveal fundamental principles of physics and ignite the spark of scientific curiosity.The Art of Bending: Exploring Elasticity and Stress.A simple paper strip, held taut between two fixed points, portrays the remarkable property of elasticity. Gently pulling on the strip causes it to elongate, aligning its molecules and storing energy within its structure. Upon release, the stored energy propels the strip back to its original length, showcasing the material's ability toresist deformation.By varying the applied force, one can investigate the relationship between stress and strain—key concepts in the study of solid mechanics. As the force increases, so does the elongation of the strip, demonstrating the direct proportionality between stress (force per unit area) and strain (deformation). This experiment provides a tangible representation of the elastic modulus, a material property quantifying its resistance to deformation.The Riddle of the Hanging Chain: Unraveling Catenary Curves.A paper suspended by two points forms a graceful curve known as a catenary. This shape, governed by the principles of equilibrium and gravity, has captivated scientists and artists for centuries. By tracing the catenary curve formed by a hanging paper strip, one can visualize and understand the mathematical relationship between the weight of the paper, the distance between the suspension points, and the curvature of the curve.This experiment not only unveils the beauty of mathematical functions but also sheds light on the forces that govern the shape of physical structures. The catenary curve finds practical applications in architecture and engineering, where it is used to design bridges, archways, and other weight-bearing structures that exhibit both strength and aesthetic appeal.The Mystery of the Balancing Rod: Center of Gravity and Equilibrium.A ruler, balanced on the edge of a table or a finger, exhibits the elusive nature of equilibrium. By adjusting the position of the ruler's center of gravity relative to the pivot point, one can explore the delicate balance between opposing forces.When the center of gravity lies directly above thepivot point, the ruler remains motionless, demonstrating the principle of stable equilibrium. However, any deviation from this ideal position results in a rotation of the ruler until a new equilibrium is reached. This experimentillustrates the fundamental role of the center of gravity in maintaining stability and preventing objects from toppling over.The Dance of Resonance: Vibrational Patterns and Standing Waves.A paper strip, clamped at one end and set into motion by a vibrating source, becomes a canvas for studying resonant vibrations. As the frequency of the vibrations matches the natural resonant frequency of the strip, it undergoes large-amplitude oscillations, forming distinct patterns known as standing waves.By varying the length of the strip or the frequency of the vibrations, one can explore the relationship between these parameters and the observed resonant patterns. This experiment provides a practical demonstration of the fundamental principles of resonance and standing waves, which find applications in music, acoustics, and other fields.The World of Possibility: Imagination and Scientific Inquiry.Paper and ruler experiments, while seemingly simple, offer a boundless world of discovery. They nurture curiosity, cultivate observational skills, and foster an understanding of scientific principles. By engaging with these experiments, one not only explores the physical world but also embarks on a journey of intellectual adventure.As scientists and budding scientists alike, let us embrace the spirit of wonder and continue to delve into the mysteries of our universe, using simple tools as our guideposts on this captivating path of scientific inquiry.。
The power of the wave Wave energy for electricity
The power of the wave Wave energy forelectricityWave energy has long been recognized as a potential source of renewable energy, with the power of the ocean's waves offering a promising solution to the world's increasing demand for electricity. The concept of harnessing wave energy to generate electricity has gained traction in recent years, as researchers and engineers explore ways to capture the immense power of the ocean and convert itinto a clean, sustainable energy source. However, there are still numerous challenges and considerations that must be addressed in order to fully realize the potential of wave energy for electricity generation. One of the key advantages of wave energy is its abundance and predictability. Unlike other forms of renewable energy, such as solar or wind power, the energy potential of ocean waves is constant and reliable. This means that wave energy has the potential to provide a stable and consistent source of electricity, without being as dependent on weather conditions or geographic location. In addition, the energy density of waves is significantly higher than that of wind or solar energy, making it a potentially more efficient and powerful source of electricity. Furthermore, wave energy has the potential to significantly reduce greenhouse gas emissions and mitigate the impacts of climate change. By harnessing the power of the ocean's waves, we can decrease our reliance on fossil fuels and transition towards a more sustainableand environmentally friendly energy system. This has the potential to not only reduce our carbon footprint, but also to protect and preserve marine ecosystemsthat are threatened by pollution and global warming. Despite these promising advantages, there are still numerous technical and economic challenges that mustbe overcome in order to fully realize the potential of wave energy for electricity generation. The development and deployment of wave energy technologies require significant investment and research, as well as the establishment of supportive policies and regulations. Additionally, the harsh and corrosive marine environment presents unique engineering challenges, as wave energy devices must be durable and resilient enough to withstand the forces of the ocean. Moreover, there are also concerns about the potential environmental impacts of wave energy technologies.The installation and operation of wave energy devices have the potential todisrupt marine ecosystems and wildlife, and it is essential to carefully consider and mitigate these impacts in the development of wave energy projects. Furthermore, there are also concerns about the visual and aesthetic impacts of wave energy devices on coastal landscapes and communities, which must be carefully addressedin the planning and implementation of wave energy projects. In conclusion, while wave energy holds great promise as a clean, renewable, and abundant source of electricity, there are still numerous challenges and considerations that must be addressed in order to fully realize its potential. From technical and economic hurdles to environmental and social impacts, the development of wave energy for electricity generation requires careful planning, research, and investment. However, with the right support and innovation, wave energy has the potential to play a significant role in the transition towards a more sustainable and resilient energy future.。
The power of the wave Wave energy harnessing
The power of the wave Wave energyharnessingWave energy harnessing has become a topic of growing interest and importancein the field of renewable energy. The power of the ocean's waves has the potential to provide a significant source of clean and sustainable energy. However, thereare various challenges and considerations that need to be addressed in order to effectively harness this power. In this response, we will explore the potential of wave energy harnessing, the current state of the technology, the environmental and social impacts, the challenges and opportunities, and the future prospects of this promising renewable energy source. The potential of wave energy harnessing is immense. The ocean is a vast and powerful resource, and waves are a constant and predictable source of energy. It is estimated that the potential wave energy resource along the coasts of the United States alone is about 2,100 terawatt-hours per year, which is equivalent to about half of the total U.S. electricity consumption. This demonstrates the significant potential for wave energy to contribute to the global energy mix and reduce our reliance on fossil fuels. Currently, the state of wave energy technology is still in the early stages of development. There are various designs and technologies being explored and tested, including point absorbers, oscillating water columns, and attenuators. These technologies aim to capture the energy of the waves and convert it intoelectricity, which can then be integrated into the existing power grid. Whilethere has been progress in the development of wave energy converters, there arestill technical and economic challenges that need to be overcome in order to make wave energy a commercially viable option. One of the key considerations in the development of wave energy is the potential environmental and social impacts. The installation of wave energy devices and infrastructure could have implications for marine ecosystems, including impacts on marine life and habitats. It is important to conduct thorough environmental assessments and engage with local communities to ensure that wave energy projects are developed in a responsible and sustainable manner. Additionally, there may be social and cultural considerations,particularly for coastal communities that rely on the ocean for their livelihoods.Despite the challenges, there are also significant opportunities for wave energy harnessing. The development of wave energy technology has the potential to create new jobs and economic opportunities, particularly in coastal regions. Furthermore, wave energy has the advantage of being a predictable and reliable source of energy, unlike other renewable sources such as solar and wind, which are dependent on weather conditions. This reliability could make wave energy a valuable addition to the energy mix, providing a stable source of power. Looking to the future, thereis a need for continued research and investment in wave energy technology. This includes improving the efficiency and cost-effectiveness of wave energy converters, as well as addressing the technical and logistical challenges of deploying and maintaining these devices in the harsh marine environment. Additionally, there isa need for supportive policies and incentives to encourage the development of wave energy projects and facilitate their integration into the energy market. In conclusion, wave energy harnessing holds great promise as a clean and sustainable source of power. The potential of the ocean's waves to provide a significant amount of energy is undeniable, and there are ongoing efforts to develop and commercialize wave energy technology. However, there are various challenges and considerations that need to be addressed, including technical, environmental, and social factors. Despite these challenges, the opportunities for wave energy are significant, and with continued research and investment, wave energy has the potential to play a valuable role in the transition to a more sustainable energy future.。
The power of the wave Wave energy conversion
The power of the wave Wave energyconversionWave energy conversion is a promising renewable energy source that has the potential to play a significant role in our transition to a more sustainable and environmentally friendly energy system. The power of the wave is immense, and harnessing this energy has the potential to provide a reliable and consistent source of power. However, there are a number of challenges and considerations that need to be addressed in order to fully realize the potential of wave energy conversion. One of the key challenges in wave energy conversion is the technical complexity of capturing and converting the energy from ocean waves into a usable form of electricity. The harsh marine environment presents significant engineering challenges, and developing technologies that can withstand the forces of the ocean while efficiently converting wave energy into electricity is no small feat. This requires significant investment in research and development, as well as ongoing maintenance and monitoring of wave energy devices. Another consideration in wave energy conversion is the potential impact on marine ecosystems. The installation and operation of wave energy devices can have environmental consequences,including the potential for disrupting marine habitats and ecosystems. It is important to carefully consider the location and design of wave energy projects in order to minimize their impact on the surrounding environment. Additionally, there is a need to carefully monitor the effects of wave energy conversion on marinelife and ecosystems in order to ensure that these technologies are truly sustainable. From an economic perspective, wave energy conversion also faces challenges in terms of cost and competitiveness. The upfront capital costs of developing wave energy projects can be significant, and there is a need for supportive policies and incentives in order to attract investment and drive down the cost of wave energy technologies. Additionally, the intermittent nature of wave energy means that it may not always be able to compete with more established forms of renewable energy, such as wind and solar power. However, with continued innovation and investment, there is potential for wave energy to become more cost-competitive in the future. Despite these challenges, there are also numerousbenefits and opportunities associated with wave energy conversion. The power of the wave is immense and consistent, offering the potential for a reliable and predictable source of renewable energy. Unlike solar and wind power, wave energy is not dependent on specific weather conditions, and can provide a more consistent source of electricity. This makes wave energy an attractive option for meeting base load energy demand, and has the potential to play a key role in ourtransition to a low-carbon energy system. Furthermore, wave energy conversion has the potential to create new economic opportunities and jobs, particularly in coastal regions where wave energy projects are likely to be situated. The development and deployment of wave energy technologies can create newopportunities for skilled jobs in engineering, manufacturing, and maintenance, as well as supporting industries such as research and development, consulting, and project management. This can help to stimulate economic growth and investment in coastal communities, while also contributing to the overall growth of the renewable energy sector. In conclusion, the power of the wave offers immense potential for renewable energy generation, but also presents a number of challenges and considerations that need to be addressed. From technical and environmental considerations to economic and competitive challenges, there are numerous factors that need to be carefully considered in order to fully realize the potential of wave energy conversion. However, with ongoing innovation, investment, and supportive policies, there is significant potential for wave energy to play a key role in our transition to a more sustainable and low-carbon energy system.。
The power of the wave Wave energy harvesting
The power of the wave Wave energyharvestingWave energy harvesting is a promising technology that has the potential to provide a sustainable and renewable source of power. The power of the wave is immense, and if harnessed effectively, it could contribute significantly to the global energy mix. However, there are several challenges and considerations that need to be addressed in order to fully realize the potential of wave energy harvesting. One of the key challenges of wave energy harvesting is the unpredictability of the waves. Unlike solar or wind energy, which can berelatively predictable, waves are much more variable and can be influenced by a wide range of factors such as weather patterns, tides, and ocean currents. This unpredictability makes it difficult to design and implement wave energy harvesting systems that can consistently generate power. Another challenge is the harsh marine environment in which wave energy harvesting systems must operate. The corrosive effects of saltwater, the potential for damage from storms and rough seas, and the need for regular maintenance and inspection all pose significant challenges for the long-term viability of wave energy harvesting systems. Additionally, the high cost of deploying and maintaining wave energy harvesting systems in the marine environment is a significant barrier to widespread adoption. Despite these challenges, there are several reasons to be optimistic about the potential of wave energy harvesting. For one, waves are a consistent and abundant source of energy, with the potential to generate power 24/7. This makes waveenergy a highly attractive option for providing baseload power, which is essential for meeting the energy needs of modern society. Furthermore, wave energy is a clean and renewable source of power, with minimal environmental impact compared to traditional fossil fuel-based energy sources. By harnessing the power of the waves, we can reduce our reliance on polluting and finite sources of energy, and move towards a more sustainable and environmentally friendly energy future. In addition, advancements in technology and engineering are helping to overcome some of the technical challenges associated with wave energy harvesting. Innovations in materials, design, and control systems are making wave energy harvesting systemsmore efficient, reliable, and cost-effective. As these technologies continue to mature, we can expect to see greater deployment of wave energy harvesting systems around the world. From a social and economic perspective, wave energy harvesting has the potential to create new opportunities for job creation and economic development. The development and deployment of wave energy technologies can create new industries and supply chains, providing employment and economic growth in coastal communities and regions with abundant wave resources. In conclusion, the power of the wave offers immense potential for sustainable and renewable energy generation. While there are certainly challenges and considerations that need to be addressed, the promise of wave energy harvesting is too great to ignore. By continuing to invest in research, development, and deployment of wave energy technologies, we can unlock the power of the waves and contribute to a more sustainable and resilient energy future for generations to come.。
The power of the wave Tidal energy
The power of the wave Tidal energy Tidal energy, also known as tidal power, is a form of renewable energy that harnesses the power of the ocean's tides to generate electricity. This form of energy has the potential to provide a consistent and reliable source of power, making it an attractive option for countries looking to reduce their reliance on fossil fuels and decrease their carbon emissions. However, there are also challenges and drawbacks associated with tidal energy, which must be carefully considered before widespread adoption. One of the main advantages of tidal energy is its predictability. Unlike other forms of renewable energy, such as wind or solar power, which are dependent on weather conditions, tides are predictable and occur twice a day without fail. This means that tidal power plants can generate electricity consistently, providing a reliable source of energy for the grid. Additionally, tides are abundant and occur in coastal areas all over the world, making tidal energy a widely available resource. Another benefit of tidal energy is its high energy density. The density of water is much greater than that of air, which means that tidal turbines can generate significant amounts of power even at low tidal speeds. This high energy density makes tidal energy a potentially efficient and cost-effective form of renewable energy, especially in areas with strong tidal currents. In addition to its predictability and high energy density, tidal energy also has the advantage of being a relatively low-impact form of renewable energy. Tidal power plants do not produce greenhouse gas emissions orair pollution, and they have a relatively small physical footprint compared to other forms of power generation. This means that tidal energy can help to mitigate the environmental impact of electricity production and contribute to efforts to combat climate change. Despite these advantages, there are also significant challenges associated with tidal energy. One of the main drawbacks is the high initial cost of building tidal power plants. The technology required to harness tidal energy is still relatively new and expensive, making it a less economically viable option compared to other forms of renewable energy, such as wind or solar power. Additionally, the harsh marine environment presents technical challengesfor the design and maintenance of tidal turbines, adding to the overall cost of tidal energy projects. Another challenge is the potential impact of tidal powerplants on marine ecosystems. The installation of tidal turbines and the alteration of tidal currents could disrupt marine habitats and affect the behavior of marine species. It is important to carefully assess and mitigate these potential environmental impacts to ensure that the development of tidal energy does not harm marine ecosystems. Furthermore, tidal energy generation is limited to coastal areas with strong tidal currents, which restricts its widespread applicability. This means that not all countries have access to tidal energy resources, and those that do may face challenges in integrating tidal power into their existing energy infrastructure. As a result, the potential for tidal energy to contribute significantly to global electricity generation is somewhat limited. In conclusion, tidal energy has the potential to provide a reliable, low-impact source of renewable energy. Its predictability, high energy density, and minimal environmental impact make it an attractive option for countries looking todiversify their energy mix and reduce their carbon emissions. However, the high initial cost, technical challenges, and limited geographic applicability of tidal energy pose significant barriers to its widespread adoption. As technology continues to advance and the environmental and economic benefits of tidal energy become more apparent, it is possible that tidal power could play a larger role in the global energy landscape in the future. However, careful consideration of its drawbacks and challenges is necessary to ensure that tidal energy development is conducted in a sustainable and responsible manner.。
The power of the wave Wave energy for irrigation
The power of the wave Wave energy forirrigationWave energy has long been recognized as a potential renewable energy source that could be harnessed for various purposes, including irrigation. The power of the ocean waves can be utilized to drive turbines and generate electricity, which can then be used to pump water for irrigation purposes. This innovative approach to irrigation has the potential to revolutionize agriculture in coastal regions, where access to freshwater for irrigation is often limited. One of the key advantages of using wave energy for irrigation is its renewable nature. Unlike fossil fuels, which are finite and contribute to climate change, wave energy is abundant and clean. By harnessing the power of the ocean waves, farmers can reduce their dependence on non-renewable energy sources and lower their carbon footprint. This not only benefits the environment but also helps to ensure a more sustainable future for agriculture. In addition to being renewable and clean, wave energy is also highly predictable. Unlike solar and wind energy, which can be intermittent and unpredictable, the tides and waves are constant and reliable. This means that farmers can rely on wave energy to power their irrigation systems consistently, regardless of the weather conditions. This predictability is essential for ensuring a stable and reliable water supply for crops, especially in regions prone to droughts and water scarcity. Furthermore, wave energy has the potential to reduce the cost of irrigation for farmers. Traditional irrigation methods, such as diesel pumps and electric motors, can be expensive to operate and maintain. By switching to wave energy, farmers can significantly reduce their energy costs and increase their overall profitability. This cost-saving benefit is particularly important for small-scale farmers who may struggle to afford conventionalirrigation systems. Another advantage of using wave energy for irrigation is its scalability. Wave energy projects can be designed to meet the specific needs of individual farmers, from small-scale operations to large commercial farms. This flexibility allows farmers to tailor their irrigation systems to their unique requirements, whether they are growing crops, raising livestock, or cultivating aquaculture. By customizing their wave energy systems, farmers can optimize theirwater usage and maximize their agricultural productivity. Despite the numerous benefits of using wave energy for irrigation, there are also challenges and limitations to consider. One of the main challenges is the initial cost ofinstalling wave energy systems. While wave energy technology has advanced inrecent years, the upfront investment required to set up wave energy infrastructure can be prohibitive for many farmers, especially those in developing countries. Additionally, the maintenance and operation of wave energy systems can be complex and require specialized skills and knowledge. In conclusion, the power of the wave energy for irrigation is a promising and innovative solution to thechallenges of water scarcity and energy sustainability in agriculture. By harnessing the renewable and predictable energy of the ocean waves, farmers can reduce their reliance on non-renewable energy sources, lower their operating costs, and increase their agricultural productivity. While there are challenges to overcome, the potential benefits of using wave energy for irrigation aresignificant and can help to create a more sustainable and resilient food systemfor future generations.。
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Design of a 2DOF Vibrational Energy Harvesting Device
S.-J. Jang, E. Rustighi, M.J. Brennan, Y.P. Lee and H.-J. Jung Journal of Intelligent Material Systems and Structures 2011 22: 443 originally published online 29 December 2010 DOI: 10.1177/1045389X10393766 The online version of this article can be found at: /content/22/5/443
INTRODUCTION
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and Yates (1996) first proposed the single-degree-of-freedom (SDOF) mechanical model of an energy harvesting device which consists of mass, spring, damper, and electromagnetic generator. Prototype devices were developed by El-Hami et al. (2001) and Williams et al. (2001). The SDOF vibration-based energy scavenging device generates the maximum power when its natural frequency matches the ambient frequency. However, this condition is difficult to guarantee when the excitation is not controllable or intrinsically frequency-variant over a broad bandwidth. The damping of the device may be increased to widen its response bandwidth at the cost of its efficiency (the peak output level reduces); that is, with conventional SDOF devices, a trade-off between the bandwidth and the power that can be harvested exists. Mechanical approaches to solve this problem have been presented by many researchers. Roundy et al. (2005) conceived a multi-degree-of-freedom (MDOF) bimorph power harvester. The power harvester is composed by multiple masses connected to each other by power absorbing elements, modeled as springs. The device may be thought as a serial connection of multiple SDOF devices. Such system, if properly designed, exhibits multiple natural frequencies, which may increase the bandwidth of the
1
Energy Mechanics Centre, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791, Republic of Korea
2 3
Institute of Sound and Vibration Research, University of Southampton, Hampshire SO17 1BJ, UK来自Published by:
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Design of a 2DOF Vibrational Energy Harvesting Device
S.-J. JANG,1 E. RUSTIGHI,2 M. J. BRENNAN,2 Y. P. LEE1 AND H.-J. JUNG3,*
harvesting device. Shahruz (2006) and Ferrari et al. (2008) instead used multiple SDOF harvesters tuned at slightly different resonant frequencies and connected in parallel at the main vibrating structure. They also widened the bandwidth by adjusting the natural frequencies of each harvester. Capitalizing on the fact that a single beam inherently has multiple modes, Tadesse et al. (2009) and Yang et al. (2009) devised a multi-modal energy harvesting system based on a single beam. They attached several magnets and piezoelectric elements in different positions on a beam, in order to gather energy from multiple modes. Nowadays, non-linearly oscillating energy harvesting devices are also actively investigated (Cottone et al., 2009; Mann and Sims, 2009; Triplett and Quinn, 2009; Barton et al., 2010; Ramlan et al., 2010). The bandwidth of the energy harvesting device also can be enhanced by sophisticated electronics. Renno et al. (2009) applied shunt load inductance to a piezoelectric energy harvester and demonstrated an increased bandwidth of power generation. Lesieutre et al. (2004) and Guyomar and Badel (2006) considered active loads presented to an energy harvester by power electronics. Cammarano et al. (2010) altered the generalized electrical load for adaptive tuning of the device and obtained the increased bandwidth. The electrical conditionings to maximize power are proposed by Nakano et al. (2007) for single transducer and by MacCurdy et al. (2008) and Scruggs (2009) for multitransducers. A single mass can have as many as three DOFs in translation and three in rotation. Hence multiple natural
ILLIAMS
*Author to whom correspondence should be addressed. E-mail: hjung@kaist.ac.kr Figures 1, 2, 5 and 6 appear in color online:
Department of Civil and Environmental Eng., Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea ABSTRACT: A novel design method for a 2DOF energy harvesting device is studied. The energy harvesting device is modeled as a rigid body supported by two parallel sets of springs and dampers. The impedance expression for the model has been developed by utilizing the concept of the inerter. The proposed design method deals with tuning two resonant peaks and equalizing the harvested power at those frequencies. As a result, the proposed energy harvesting device is particularly effective at two frequencies and has increased bandwidth as well as reduced size and weight in comparison with previous SDOF devices. A numerical design example is provided to show effectiveness of the proposed method. Key Words: vibrational energy harvesting device, 2DOF system, impedance method.