Noncommutative massive Thirring model in three-dimensional spacetime

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Non-manifold Models

Chapter6Non-Manifold ModelsThe normal objects that you meet in everyday life are called‘‘manifold’’objects. Which means,putting it glibly,that at every point on the surface the neighbour-hood around the point is homeomorphic to a disc.You may,or may not want to know that.Figure6.1,shows an alternative way of understanding this,from Braid, that,at every point on the outside of the object,a small enough sphere will be cut into two pieces,one inside the object and one outside.The following potted history is what I believe to be true,but if someone ever writes a deﬁnitive history of CAD then there may be other factors of which I am not aware.In the original Boundary Representation modelling systems only valid solids were considered.In the BUILD research system,as an intermediate step,it was possible to representﬂat objects,but these were usually only shapes which were to be swept.Towards the end of the1970s an internordic project,GPM,was set up to develop methods for‘‘Geometric Product Modelling’’was set up incorporating a number of modelling methods.In Denmark the user system was developed.In Norway an‘‘Assembled Plate Construction’’(APC)module(SINTEF)and a surface module were developed(SI).In Sweden and Finland the volumetric modelling module was developed.The APC module was a specialised,advanced module for modelling constructions made from thin plates.As part of the volume module it was intended to be able to interface with both this module and the surface module,so thin plate models were introduced as part of the volumetric modelling system[1].One of the Swedish ideas was that,by mixing different representations in the same modelling framework,you could represent different stages and levels of models.In the beginning you might have a simple sketch.This might then beﬂeshed out into partial models,idealisations of the volumetric shape.For production needs these might need to be expanded into full volumetric models.As the lifetime of a product develops it may prove useful to go back to idealisations and maybe even sketches. This is described by Kjellberg[2],who,as far as I know,pioneered this method,but his dissertation is in Swedish so is not so accessible.One of the examples he used is illustrated in Fig.6.2,a simpliﬁed model of an excavator.315 I.Stroud and H.Nagy,Solid Modelling and CAD Systems,DOI:10.1007/978-0-85729-259-9_6,ÓSpringer-Verlag London Limited2011The whole excavator is an assembly of models with different characteristics.The body of the excavator and the tracks are solid models,the arm is a wireframe model and the scoop is a compound sheet model.So,for non-manifold models in CAD,it is necessary to distinguish between three types of special and non-manifold model:1.Wireframe models.2.Sheet models.3.Non-manifold solid models.These can be integrated into the same datastructure for easy transition between applications.For wireframe models the loop and face information is ‘‘ignored’’,that is,set to NULL.Sheet models are like degenerate solid models,with the limit edges corresponding to thin faces.Non-manifold solids have coinciding portions.Some systems keep solids apart from sheet models and wireframe models,others integrate them.This is a strategic question which,of course,affects theuser Fig.6.1Manifold object deﬁnition3166Non-Manifold Modelsbut is up to the CAD developer.Neither strategy is particularly bad,they both have advantages and disadvantages.Integrating them means that the user has aﬂuent design environment and that common functionality is shared.Keeping them apart means that there is less chance of error,in creating sheet models instead of solids. One thing that should never be done,though,is to have solids with sheet and/or wireframe elements integrated into the same model,such as the one shown in Fig.6.3.This is possible,but sheet and wireframe models are idealisations of something,where a solid model is a full solid.Integrating them would mean that you have a model which has to be interpreted differently in different places,which is not particularly a good idea.Nobody does this,as far as I know,so it should not be a problem.6.1Datastructure NeedsA common method for implementing non-manifold modelling is to use the so-called‘‘STAR’’representation.The development that allowed this was to intro-duce the loop-edge links so that edges could refer to more than two loops(loops are face boundaries).In the original Boundary Representation(Brep)datastructure, in BUILD,there was aﬁxed restriction that there were two loops at every edge. They could be the same loop,but there were never more,because such objects were unrealisable.The addition of loop-edge links to the datastructure,which appeared in the GPM Volume Module,allowed rings of links around the edge and, hence,any number.Figure6.4shows this.A requirement for this method of representation is that the links are ordered around the edge.Figure6.5illustrates this.On the left of theﬁgure you see a normal case.The large black dot represents the edge,seen in cross-section.The lines represent faces and the small dots are just to indicate where there is material. Turning around the edge counter-clockwise,as indicated by the arrow,the linksbetween the edge and the faces are classiﬁed as‘‘enters’’or‘‘leaves’’depending onwhether you enter the material or leave it.There is a sequence of alternating pairs in a correct ﬁgure.On the right of Fig.6.5is an incorrect case.The sequence is ‘‘enters–leaves–enters–leaves–enters–enters–leaves–leaves’’.The double ‘‘enters’’and ‘‘leaves’’indicate that there is material within material,i.e.that there is a self-intersecting object.Note that this ordering procedure can be done for volume objects,but for sheet objects the enters–leaves classiﬁcations with coincide,and ordering is difﬁcult.The star representation is not necessary to implement non-manifold models,the non-manifold condition is a geometric condition,not a topological one.In the GPM project edges were allowed to refer to only two faces,even though loop-edge links were part of the datastructure.It was felt that it was more natural to duplicate edges.Edge duplication also has an advantage in that the meaning ofthe enters leaves enters leaves entersleaves entersleaves entersleavesenters enters leaves leavesFig.6.5Ordering edge links around the edge3186Non-Manifold Modelsdatastructure entity connections is unambiguous.With the star representation it is not clear whether the object parts are just connected at the non-manifold edge,or whether they just miss each other.It is important to know this because performing an operation on a non-manifold edge should entail a conversion before the oper-ation.This conversion involves pairing up the loop-edge links and duplicating edges.A visual comparison is shown in Fig.6.6.For a non-manifold edge,as shown at the top of theﬁgure,the star version is shown at the bottom left and the degenerate version on the bottom right.For the star version an advantage is that the links are associated,it is clear that the edge is a special case.Unless there is a link between the duplicated elements this connection is not explicit.The ambiguity problem is illustrated graphically in Fig.6.7.The star arrangement is shown at the top of theﬁgure.If you group edge link1with edge link2and links3and4then you get the double edge joined case at the bottom left. If you group link2with link3and4with1then you get the arrangement on the bottom right,where the objects are separate,only being joined at the vertices of the edges.The problem is that there is no way for the CAD system to know which one you mean.This means that operations,such as chamfering,could have two interpre-tations,as illustrated in Fig.6.8,as already mentioned in Sect.4.7.Of course, what you would like is the CAD system to ask you which you mean,but at themoment the trend is to ignore these edges.The point of explaining this is two-fold.The ﬁrst is to explain why,sometimes,you get discrimination between model elements to which you would like to apply an operation.Secondly,to explain the notion of edge duplication and edge-link pairing,which is how to interpret the multi-link edges.6.2Wireframe ModelsWireframe models are another example of partial models which can be useful for special purposes,such as sketching the centre-lines of pipework.At one time CAD systems used wireframe models exclusively.6.2.1Wireframe DatastructureThe datastructure of wireframe models is very simple,consisting of‘‘nodes’’and ‘‘links’’,as shown in Fig.6.9.The nodes are represented by vertices and the links by edges to use the same elements as for sheet objects and solids.While these are enough for simple shapes,the lack of surface information is a handicap for many functions,from drawing to manufacturing.A wireframe graphics view of an object is shown in Fig.6.10to emphasis this.6.2.2Impossible WireframesIt is also possible to make objects which are not realisable,as in Fig.6.11.Sheet objects and volume objects are Eulerian objects,which means that they follow the formula described in Sect.2.7.3.This means that there are restrictions on how you build models,which precludes models such as that in theﬁgure.Other models, such as Möbius strips,or Klein bottles can also be created using wireframe techniques,but are excluded using volumetric techniques.More usual than these recreational objects,though,is that it is possible to create erroneous objects.6.2.3Wireframes and ModellingAn old research topic was the automatic conversion of wireframe models to solids. It is not possible to guarantee a conversion and some counter-examples exist of objects which cannot be converted.A feasible use for wireframe models is as a support for sketching or they can be used as idealisations and then converted,as with the operation described in Sect.4.13.One current use for wireframes is for deﬁning two-dimensional shapes to be set into surfaces,as has already been described in Sect.3.7.They can also be used for modelling curves in a geometric package and,for example,swept to create sur-faces,as will be described in Sect.6.3.1.6.2.4Wireframe Experiments6.2.4.1Creating PipeworkMake a shape like that on the left of Fig.6.12.Extrude a circle along this path to create a simple pipe.You canﬁnish the pipe using the shelling operation to create the interior.If you have a shape like that on the right of theﬁgure you cannot create it in onepiece with the extrusion along path operation.You can create the basic shape aswith theﬁgure on left and then add the additional shape with a second extrusion along a path.The questions concern how to perform the various parts of the operation.If, after theﬁrst extrusion,the basic shape is turned into a extruded shape then the second operation will create interior elements rather than the desired shape. The second shape should be added before the shelling operation to create the interior.However,this creates theﬁnal object in one piece,but it would normally be created in several shaped pieces which would be welded together. This can be done by creating the outer shape as a solid model,separating it into elementary parts,and then creating the individual shelled pieces to be made.The purpose of this long explanation is to say that,while the facilities may exist to create simple models,real applications need to be based around correct inter-pretations rather than using standard tools.6.3Sheet ModelsSheet models are a useful tool for representing idealisations of thin-plate models or for representing surfaces,as described in Sect.5.8.1.Sheet models are non-manifold because they are inﬁnitely thin,but in some applications it is quite natural to use them rather than volumetric models.The GPM APC module was mentioned at the beginning of this chapter,and there was a successful oil rig platform design application based on it.Other applications,such as layouts,for modelling shapes to be cut from cloth or shapes to be cut from thin metal sheets, do not need volumetric models.It is more efﬁcient and more natural to use sheet models.An important part of the use of sheet models is their interpretation as ideali-sations of thin-plate models.In this respect,the duplication of edges is more natural than using a star representation for coincident edges.The duplicated edges lie on different sides of the sheet objects and would be slightly apart if the sheet object were expanded to produce a volumetric model.This was one of the reasonsthat this method was used in the GPM volume module.6.3.1Extruding Wireframe ModelsA common operation is to extrude curves to produce surface models.This means that edges go from being non-Eulerian to being Eulerian as part of the extrusion process.The edges go from being linked through vertices to being linked into chains as borders of faces.This was also discussed brieﬂy in Sect.4.2.It is important to know how wire extrusion is integrated into the CAD system,whether sheet models are separate from volumetric models or coexist.Branching wire objects have already been mentioned in Sect.4.11.These are usually excluded from extrusion operations by CAD systems,so will not be dealt with further here.Figure6.13shows an object that was used for comparison of solid modelling systems for a seminar organised by the CAM-I organisation in1983.It is an object, reportedly of a gun-platform,which is composed of thin-walled parts.As part of the GPM Volume module demonstration,this part was shown both as a sheet model and as a set ofﬂattened shapes to be cut from plate material,shown in Fig.6.14.The method for doing this is described in Stroud[3].The operation has not appeared in commercial CAD systems,as far as I know,but it shows what could be done as part of a special application.6.3.2Joining Sheet ObjectsJoining sheet objects representing surface portions has already been described in Sect.5.8.1.The procedure is shown in Fig.6.15.Each edge has two loop-edge links,linked in a chain.The edge-link pairs are regrouped to form two chains,intheﬁgure,or one if the edges are merged.Figure6.16shows how the loop-edge links are rearranged.The case where the edges are in the same direction is shown in the left hand column of theﬁgure.The case where the edges are in the opposite direction is shown in the right-hand column.The original arrangement is shown at the top.Edge e1has left link L1and right link R1.The edge to which it is to be joined is e2,with left link L2and right link R2.If the edges are in the same direction and both are kept,middle left,then link L1 is paired with link R2and link L2is paired with link R1.If the edges are merged, bottom left,then the links are arranged in the circular sequence L1;R2;L2;R1.If the edges are in opposite directions,and both are kept,middle right,then L1is paired with L2,which becomes a right link,and link R1is paired with R2,which becomes a left link.If the edges are merged,bottom right,then the links are merged into the sequence:L1,L2(which becomes a right link),R2(which becomes a left link),R1.6.3.3Volume Models to Sheet ModelsSection4.9describes the simple way of converting volume models to sheet modelsas one step in the shelling process.An operation that youﬁnd in CAD systems is to unfold,orﬂatten,volume models.This was described in Sect.4.10.These methods allow a designer to create a part as a solid and then convert it to a sheet model to be made from thin material.Converting a volume model to a sheet models is aﬁrst step in at least oneﬂattening algorithm.This conversion allows the concave edges along which the object is to be bent to be marked as grooved forﬁnishing operations after cutting.6.3.4Sheet Model Experiments6.3.4.1Extruding WiresFirst of all,create an open shape as a sketch in the volume modelling part and extrude it in a straight line or circular arc,as in Fig.6.17.This is the same experiment as for extrusion and is intended to show whether or not sheet models and volume models are integrated or separate.The question is not whether the CAD system can do it or not,these are simple shapes,but whether they are allowed to coexist or not.Another extrusion experiment to try on simple shapes involves wires with one edge in the extrusion direction,as shown in Fig.6.18.The shape on the top left of theﬁgure should probably cause an error,as the extruded shape,bottom left,would have a dangling edge,which is not a good idea.The shape shown top middle,though,is more debatable.The result of an extrusion would be a valid shape,bottom middle,though the internal edges,shown dotted,would have to be handled properly.The third shape,top right,would cause problems,because the extrusion would leave a single wire edge in the middle,or the shape would have degenerate parts.Test these three shapes to see if the CAD system allows them or not.For the shape on the right,make sure that the middle edge is longer than the extrusion distance.6.3.4.2Extruding Branching WiresThis is another experiment that has been suggested before,in the section on extrusion.Extruding branching edges should not be a problem,except for critical cases where one or more edges are in the extrusion direction or there are coin-cident edges.The reason for not implementing this is a strategic decision by CAD implementers about the complexity allowed.The problem is to work out the connections at the complex branch-points.If there are at most two edges at every vertex then there is no problem.If there are more then a geometric test is needed to sort out pairings.One of the edges is taken as a base edge,the zero degree edge and the other edges are ordered using their tangent vectors,projected onto the plane deﬁned by the common vertex and the extrusion direction(Fig.6.19).This method wasdeveloped by Müller[4].Note that edges3and4have the same tangent direction,but this is sorted out in Müller’s method by using the curvature.The method will not work,though,if there are coincident edges or edges parallel to the extrusion direction.An alternative is to slice the edges to create a degenerate face,which is then extruded.See Fig.6.20.This can then be extruded using a normal face extrusion and then the edges collapsed back as a ﬁnishing process.The actual details of how this is done in a particular CAD system are not really important,the question is whether or not the system allows you to extrude branching wires.6.3.4.3Joining Three or More Sheet ObjectsDedicated CAD systems for thin plate modelling should be able to handle this case,though as part of a general CAD system this may not be allowed.A simple test is shown in Fig.6.21.Create a line on the Z =0plane,say from ðÀ50;0Þto ð0;0Þand extrude it 60.Create a second line,from ð30;À50Þto ð0;0Þand extrude this 60,as well.Finally,create a third line,from ð30;50Þto ð0;0Þand extrude this 60,the same distance for all three sheet objects.Now try joining them.In the same way that branching wires can be handled,sheet merging can be handled if the CAD system developer is prepared to invest the effort.6.3.4.4Joining Sheet Models Without Matching EdgesThis experiment is to test how much effort has been put into sheet modelling in the CAD system.This is equivalent to a Boolean operation on sheet models and is not impossible,technically,just requires some effort from the CAD system implementer.On the Z =0plane,draw a semicircle,or,if you wish,a full circle,radius 25,say.Extrude this 50to create the ﬁrst sheet.Now make a line just touching the middle of the semicircle,from (25,0)to (50,0),say,as illustrated in Fig.6.22.Try to join them and check whether or not the system allows this.6.4Partial ModelsPartial models are a special type of sheet model which are useful as mechanisms for applications.They have faces and surfaces on one side but nothing,or maybe one unsurfaced face,on the other side,as was done in the BUILD system.If there is nothing on the back of the partial model,as is normal,then the boundary edges are only partially deﬁned,with only one loop-edge link.You would not expect to see these as part of the CAD system,they are tools for applications or intermediate results,perhaps.Partial models act as though they have unlimited material behind them.Provided any operation does not go beyond the boundaries of the partial model they act as normal volumes.An application using partial models will be described in Sect.10.3.2.A simple illustration of the differences between sheet objects and partial objects is shown in Fig.6.23.If you were to add a cylinder to a square shape,shown in Fig.6.23a you would get the result in Fig.6.23b if the square shape were a sheet object and the result in Fig.6.23c if the square shape were a partial object.The reason is that the sheet object would have two intersections and both top and bottom of the cylinder would be classiﬁed as outside the sheet.On the other hand, with a partial object,there would be only one intersection,with the deﬁned face, and only the top of the cylinder would be classiﬁed as outside the object.In addition,the addition of the cylinder to the sheet object should really be classiﬁed as invalid,since this would create a mixed object with volumetric and sheet parts.6.5Non-Manifold Volume ModelsBeware of non-manifold portions in volumetric models.Although creating such model parts is technically correct,integration in alloperations seems patchy,at least at the time of writing.The problem of handling3326Non-Manifold Models star representations and pairing loop-edge links has already been mentioned.As with sheet models,this comes back to having a clear method of interpretation of what the non-manifold edge means:is it where there is material or is it where objects touch without being joined?Similar considerations exist for objects just touching at vertices.Note,also,that there are two kinds of non-manifoldness that you might create. Theﬁrst kind is where there are edges with more than two faces or vertices with multiple edge sets,the second is where two elements touch without having common topological elements.An example of the second type is shown in Fig.6.24.The object was created using an extrusion along a path,described in Sect.4.2.8.The sort of object shown in theﬁgure is hard for a modelling system to resolve because the normal point-set considerations cannot be used to sort out the object. Points have neighbourhoods which are not homeomorphic to discs,if you prefer to have it that way.An attempt to subtract the object in Fig.6.24from a block failed because,the system said,it could not sort out the tangential relationships.Sorting out this type of non-manifold object would require a special type of Boolean operation,for evaluating self-intersecting objects,which,instead of taking two objects and comparing their faces,compares the faces of a single object with each other.It is not impossible to implement,but I have not yet seen such an operation in a CAD system.Such an operation is linked with another topic,called ‘‘model checking’’or‘‘model healing’’,which will be described brieﬂy in Sect.14.3.6.5Non-Manifold Volume Models333 6.5.1Datastructure ImprovementsThe inherent ambiguity of the star representation as commonly implemented is a drawback,but there are ways of improving it.The best work I know in this area was by Luo and Lukacs[5,6].They introduced elements called‘‘bundles’’for handling non-manifold vertices and‘‘wedges’’for non-manifold edges.Bundles and wedges can be thought of as being equivalent to loops for faces in that they allow multiple associations between datastructure elements.A full treatment of this,though,lies outside the scope of this chapter,which is intended to deal with practical aspects of the use of non-manifold solids.The reason for mentioning this is that the current structure might change to avoid this ambiguity.If it does,in the future,you may be prompted to tell the system whether you mean objects to‘‘touch-and-join’’or‘‘touch-but-miss’’.If you are asked,then it means that the system can distinguish between the cases and operations such as chamfer or blend on non-manifold edges and vertices may work.If you get this kind of message,check what happens by blending the non-manifold model part.6.5.2Non-Manifold Volume ApplicationsTo some extent,non-manifold modelling is a solution in search of a problem. The use of sheet-and wireframe-models as idealisations is a clear and useful facility that has proved its usefulness.The uses for non-manifold solid models is less clear.One suggestion has been to use them forﬁnite-element mod-elling.However,ﬁnite element models tend to have a large number of ele-ments and the overheads associated with a volume would make these difﬁcult to handle.One more appropriate application area is that described by Luo and Lukacs and involves the use of non-manifold volume models for process planning.This is a development building on an idea proposed by Malcolm Sabin,one of the most inﬂuentialﬁgures in CAD/CAM.At a conference in1983Sabin suggested building back a CAD model to its stock as a way of manufacturing planning. Lukacs and Luo’s idea was to keep the built-back volumes separate and to link them with the CAD model to create a compound,non-manifold model.The sep-arate parts could then be easily identiﬁed for manufacturing planning,I know of no CAD systems using such methods,though.6.5.3Volumetric ExperimentsTheﬁrst three of these come from previous exercises.They are simple ways of creating non-manifold solids.6.5.3.1Touching Edges by ExtrusionThis exercise was described in Sect.4.2.Make a square shape100Â100.Extrude it 100units.On the top face,create a new square,100Â100,which touches one of the edges of the top face and extrude this100units to create the object.See Fig.6.25.6.5.3.2Touching Vertices by ExtrusionAnother exercise from Sect.4.2.This is a similar exercise to the previous one, except that the shapes touch only at a vertex.Make a square shape100Â100. Extrude it100units.On the top face,create a new square,100Â100,which touches one of the edges of the top face and extrude this100units to create the object.See Fig.6.26.6.5.3.3Extruding Touching ShapesYet another exercise from Sect.4.2.Make a pair of triangles touching at a vertex, as shown in Fig.6.27.The order of deﬁnition shown be p1-p2-p3-p1and p4-p5-p2-p5.You should not try making this as p1-p5-p4-p3-p1,which will not create the important vertex in the middle.The actual size of the triangles is not important,just that they touch at one vertex. Extrude the touching triangles about the length of the side to give a reasonable thickness.The question is what happens with the common vertex,is it one edge or two?6.5.3.4Touching FacesThis creates the shape shown in Fig.6.24.In the YZ plane,Y=0,create theshape shown in Fig.6.28.On the XY plane,Z=0,create a25Â25square shapecentred about one of the end vertices of the shape shown,marked A and B in the ﬁgure,and extrude it along the path to create the shape.This method of creating touching faces may not work in some systems which use Boolean operations to join sub-extrusion elements.6.5.3.5Chamfering to Create Touching ElementsCreate a thin shape such as that shown in Fig.6.29a.The arms might be75units long and10units wide.Extrude the shape75to give a volumetric model like that shown in Fig.6.29c.Now chamfer the convex edge as shown in two dimensions inFig6.29b,and in three dimensions in Fig.6.29d.If the depth of the chamfer is correct,armthicknessÂﬃﬃﬃ2p,then you get a non-manifold edge,shown dotted in Fig.6.29d.If Boolean operations are used to create the chamfer then the edge might be a star non-manifold edge.If a simple local operation is used then the edge may touch the face,but not be associated with it.You can test this by attempting to blend the edge.6.6Chapter SummaryThis chapter deals with the subject of non-manifold and idealised models.While idealised models have a clear use as design sketches,non-manifold volume models have a less clear role in modelling.Being able to work with idealisations as part of the design process addsﬂuency to CAD use and may also help by providing clearer design intent.。

On the negative effective mass density in acoustic metamaterials

There is no actual negative mass/mass density in real materials indeed. The negative effective mass/mass density is the result of inaccurate modeling of acoustic metamaterials. In the present study, we consider a one-dimensional lattice consisting of lattice masses each of which contains an internal mass. This simple lattice system is employed to illustrate how the
On the negative effective mass density in acoustic metamaterials
H.H. Huang a, C.T. Sun a,*,G.L. Huang b
a School of Aeronautics and Astronautics, Purdue University, W. Lafayette, IN 47907, USA b Department of Systems Engineering, University of Arkansas at Little Rock, Little Rock, AR, 72204, USA
* Corresponding author. Tel.: +1 765 494 5130; fax: +1 765 494 0307. E-mail address: sun@ (C.T. Sun).

Noncommutative KKLMMT Model

a r X i v :a s t r o -p h /0605442v 2 24 M a y 2006Noncommutative KKLMMT ModelQing-Guo Huang School of physics,Korea Institute for Advanced Study,207-43,Cheongryangri-Dong,Dongdaemun-Gu,Seoul 130-722,Korea Institute of Theoretical Physics,Academia Sinica P.O.Box 2735,Beijing 100080The interdisciplinary center of theoretical Studies,Academia Sinica P.O.Box 2735,Beijing 100080huangqg@kias.re.kr In the noncommutative space-time the ﬁne tuning in KKLMMT model can be signif-icantly released and a nice running of spectral index ﬁtting the WMAP three year data can be achieved.The ﬁtting results show that the noncommutative mass scale is roughly 5×1014Gev.The string mass scale is higher than the noncommutative scale unless thestring coupling is smaller than 10−10.May,2006Inﬂation[1]economically solves the horizon problem,ﬂatness problem and so on in the hot big bang model.It also predicts a nearly scale-invariant spectra of primordial scalar and tensor perturbations.A wide range of astronomical data sets are consistent with the predictions of theΛCDM model[2].The results of WMAP three data are given in[2].ForΛCDM model,WMAP three year data only shows that the index of the power spectrum satisﬁesn s=0.951+0.015−0.019.(1) A red power spectrum is favored at least at the level of2standard deviations.If there is running of the spectral index,the constraints on the spectral index and its running aren s=1.21+0.13−0.16,αs=dn sNoncommutative geometry can naturally emerge in string theory.In[16]the com-mutator between space and time coordinates is not zero if there is an electricﬁeld on the brane,which says[t,x]=iθ=iM−2nc,(4)whereθ=11−˜E2,˜E=E/E cr and E cr=1/(2πα′)is the critical electricﬁeld.Beyond that value strings can materialize out of the vacuum,stretch to inﬁnity and destabilize the vacuum[16,17].This noncommutativity leads to an uncertainty relation between time and space,which was advocated as a generic property of string theory even when no electric ﬁeld is present[18].In a quantum theory,time coordinate labels the evolution of the system.We don’t know how the time could fail to commute.Here we adopt the strategy proposed in[19] to explore how the space-time noncommutative eﬀects quantitatively modify the evolution of the quantumﬂuctuations during the period of inﬂation.There are many discussions about the parameter space of the KKLMMT model,see for example[11,13,14].In this short note,we parameterize KKLMMT model with potentialV=1φ4 ,(5)hereM4=27(2π)3g s,(7) where h is the warped factor in the throat and M obs=M s h is the eﬀective string scale on the brane[12].The warped factor makes D3-brane lighter.Theβterm comes from the Kahler potential,D-term and also interactions in the superpotential,and H is the Hubble constant.Generallyβis of order unity[10],but to achieve slow roll,it has to beﬁne-tuned to be much less than one[11,12,15]and it seems quite unnaturally.On the other hand,in [20-22],the authorsﬁnd the space-time noncommutative eﬀects can accommodate a large enough running.See[23,24]for the recent progresses.This model was later extensively studied in[25].Other models with a large running are discussed in[26,27].The spacetime noncommutative eﬀects are encoded in a new product among func-tions,namely the star product,replacing the usual algebra product.The evolution of thebackground is homogeneous and the standard cosmological equations of the inﬂation will not change.The value ofφ,namely,φN at the number of e-folds equals N before the end of inﬂation isφ6N=24NM2p M4m(β),(8)wherem(β)=(1+2β)e2βN−(1+β/3)18 φN2Nm(β) 2,ηv=β613Nm(β) β+124π2ǫv(1+µ)−4= 25M4p 23f−42,(12)µ=H2k2/(a2M4nc)is the noncommutative parameter,H and V take the values when the ﬂuctuation mode k crosses the Hubble radius,k is the comoving Fourier mode and M nc is the noncommutative mass scale.The factor(1+µ)−4in eq(11)comes from the space-time noncommutative eﬀects.Substituting eq.(6)and(8)into(11),we haveφN8 16(β)f14 ∆2R 14√2m13(β) β+1The spectral index and its running aren s =1−6ǫv +2ηv +16ǫv µ,αs =−24ǫ2v +16ǫv ηv −2ξv −32ǫv ηv µ,(15)with the tensor-scalar ratior =16ǫv .(16)The noncommutative eﬀects encode in the parameter µand these eﬀects are negligible if ǫv is too small.For β[15]and thenoncommutative eﬀects When βbecomes large,ǫv becomes also for β=0.25are showed in ﬁg.1.Figure 1.The range by WMAP three year data at the We also take β=0.respectively.The ﬁtting results for eq.N =47.7+1.6−3.7,0.25,N =38.4+1.4−2.8,0.3,(17)at the level of one stand of e-folds N is showed in ﬁg.2whereFigure2.Here the range ofβis0.22≤β≤0.31.The range between the twored lines is allowed by the WMAP three year data at the level of1σ.The blue line cor-responds to n s=1.21andαs=−0.102.The space-time noncommutative eﬀects can improve KKLMMT model to nicely ac-commodate the spectral index and its running.Requiring N≥47yieldsβ≤0.25.Before the end of this note,we also want to work out the noncommutative mass scale. 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田纳西伊斯曼不同模态对应的参数

田纳西伊斯曼模型是一种用于描述物质的多种性质和相互作用的理论模型。

它涉及了多种参数和模态，包括了电子结构、声子振动、磁性、电子输运等多个方面。

在这篇文章中，我将深入探讨田纳西伊斯曼模型中不同模态对应的参数，以帮助您全面地理解这一复杂而重要的理论模型。

1. 电子结构参数在田纳西伊斯曼模型中，电子结构参数是非常重要的一部分。

它涉及了能带结构、费米面形状、赝势和杂质等多个方面。

这些参数对于描述材料的电子行为以及其宏观性质起着关键作用。

通过对电子结构参数的深入理解，我们可以更好地理解材料的导电性、光学性质以及各种相变行为。

2. 声子振动参数声子振动在固体物理中是一个非常重要的概念，它涉及了晶格动力学、热传导、介电性质等多个方面。

在田纳西伊斯曼模型中，声子振动参数对应着晶格势能、声子色散关系、声子-声子相互作用等。

这些参数影响着材料的热力学性质、热导率、热膨胀系数等重要性质。

3. 磁性参数磁性是固体物理中的一个重要研究领域，而在田纳西伊斯曼模型中，磁性参数对应着费米面拓扑、交换相互作用、铁磁共振、磁化率等多个方面。

这些参数直接影响着材料的磁性行为，包括铁磁性、反铁磁性、自旋玻璃等。

4. 电子输运参数在实际应用中，我们经常关心材料的电子输运性质，比如电导率、霍尔系数、电子迁移率等。

田纳西伊斯曼模型也能描述这些电子输运参数，它涉及了载流子散射、电子-声子相互作用、能带结构等多个方面。

总结回顾通过对田纳西伊斯曼模型中不同模态对应的参数的综合讨论，我们可以看到这一理论模型的深度和广度。

从电子结构到声子振动、磁性以及电子输运，田纳西伊斯曼模型提供了一个全面描述物质性质的框架。

它也提醒我们，物质的多种性质是相互关联、相互作用的，需要综合考虑才能全面理解。

个人观点和理解在我看来，田纳西伊斯曼模型是一个非常重要的理论框架，它为我们理解和描述物质的多种性质提供了重要的工具。

通过深入研究不同模态对应的参数，我们可以更好地理解材料的性质，并且为材料设计和应用提供理论指导。

非线性动力学外语词

非线性动力学外语词非线性动力学非线性动力学 nonlinear dynamics @M动态系统 dynamical system SG=]@原象 preimage u@p控制参量 control parameter -"_h7>霍普夫分岔 Hopf bifurcation 6.k4倒倍周期分岔 inverse period- doubling bifurca-tion5-;>ZO全局分岔 global bifurcation Ms6魔[鬼楼]梯 devil's staircase @h[非线性振动 nonlinear vibration B}up<侵入物 invader -s锁相 phase- locking I`![!猎食模型 predator- prey model :y[状]态空间 state space w5O[状]态变量 state variable xg7JU吕埃勒-塔肯斯道路Ruelle- Takens route 0{斯梅尔马蹄 Smale horseshoe Cn/rpJ混沌 chaos CA!WI|李-约克定理 Li-Yorke theorem >>李-约克混沌 Li-Yorke chaos '2;洛伦茨吸引子 Lorenz attractor ]/9混沌吸引子 chaotic attractor zKAM环面 KAM torus "I/费根鲍姆数 Feigenbaum number {.费根鲍姆标度律 Feigenbaum scaling !6KAM定理Kolmogorov-Arnol'd Moser theorem, KAM theorem q3`勒斯勒尔方程 Rossler equation ?C_R9混沌运动 chaotic motion z&q|w费根鲍姆函数方程 Feigenbaum functional equation xS+l1蝴蝶效应 butterfly effect ;cA同宿点 homoclinic point bcx异宿点 heteroclinic point [MH$同宿轨道 homoclinic orbit J(y6异宿轨道 heteroclinic orbit M)PL_排斥子 repellor-XI超混沌 hyperchaos zg阵发混沌 intermittency chaos }.内禀随机性 intrinsic stochasticity l含混吸引子 vague attractor [of Kolmogorov]V AK hBkc奇怪吸引子 strange attractor :SFPU问题 Fermi-Pasta- Ulam problem, FPU problem #0x初态敏感性 sensitivity to initial state @反应扩散方程 reaction-diffusion equation -}CKy非线性薛定谔方程 nonlinear Schrodinger equation r,CP}w逆散射法 inverse scattering method K z/A孤[立]波 solitary wave u~i("[奇异摄动 singular perturbation /正弦戈登方程 sine-Gorden equation FU1{AN科赫岛 Koch island #Py豪斯多夫维数 Hausdorff dimension uKS[动态]熵 Kolmogorov-Sinai entropy, KS entropy 4ZU3卡普兰-约克猜想 Kaplan -Yorke conjecture #eX6康托尔集[合] Cantor set x8)c$;欧几里得维数 Euclidian dimension p+茹利亚集[合] Julia set "科赫曲线 Koch curve t谢尔平斯基海绵 Sierpinski sponge G李雅普诺夫指数 Lyapunov exponent r?M7芒德布罗集[合] Mandelbrot set 9l李雅普诺夫维数 Lyapunov dimension 0谢尔平斯基镂垫 Sierpinski gasket .d雷尼熵 Renyi entropy V'(s雷尼信息 Renyi information Ynv分形 fractal @Fv\7w分形维数 fractal dimension Z分形体 fractal s&f胖分形 fat fractal L退守物 defender cu Xx覆盖维数 covering dimension 8!nR.信息维数 information dimension WT度规熵 metric entropy ['R!j多重分形 multi-fractal (关联维数 correlation dimension 'QD*o拓扑熵 topological entropy (ZUa:拓扑维数 topological dimension Bv?J拉格朗日湍流 Lagrange turbulence 8.\N3布鲁塞尔模型 Brusselator^贝纳尔对流 Benard convection iE瑞利-贝纳尔不稳定性 Rayleigh-Benard instability i'LW0闭锁键blocked bond ep5%cl元胞自动机 cellular automaton Os2浸渐消去法 adiabatic elimination ^zS连通键 connected bond, unblocked bond自旋玻璃 spin glass %0h窘组 frustration +M窘组嵌板 frustration plaquette"窘组函数 frustration function P-zio窘组网络 frustration network 0n;@窘组位形 frustrating configuration 6)逾渗通路 percolation path d!,m逾渗阈[值] percolation threshold h入侵逾渗 invasion percolation hF!K1扩程逾渗 extend range percolation 6XH"z 多色逾渗 polychromatic percolation U3F 快变量 fast variable %/5A'f慢变量 slow variable >k卷筒图型 roll pattern SyN六角[形]图形 hexagon pattern d1)jx主[宰]方程 master equation r[vdYS役使原理 slaving principle \RG>]~耗散结构 dissipation structure )离散流体[模型] discrete fluid !UMP(自相似解 self-similar solution /{,a%协同学 synergetics|`sX自组织 self-organization uz跨越集团 spanning cluster DdZ~k奇点 singularity \y"Z多重奇点 multiple singularity ?C多重定态 multiple steady state Kr不动点 fixed point Sm吸引子 attractor g48p自治系统 autonomous system #:J结点 node dx'焦点 focus Z O简单奇点 simple singularity =7?h单切结点 one-tangent node NFxld3极限环 limit cycle yeIty\中心点 center k鞍点 saddle [point] jgwd4映射 map[ping] a1O:h<逻辑斯谛映射 logistic map[ping] !pXB5~沙尔科夫斯基序列Sharkovskii sequence O#~面包师变换baker's transformation F1Xx8Z吸引盆 basin of attraction L生灭过程 birth-and death process ufz台球问题 biliard ball problem 3i<f^y< p="">庞加莱映射 Poincar'e map tpz[C:庞加莱截面 Poincar'e section $pN猫脸映射 cat map[of Arnosov] $\[映]象 image L^}uD揉面变换 kneading transformation 3JQo$9倍周期分岔period doubling bifurcation e_)}单峰映射single hump map[ping] \Bl4圆[周]映射 circle map[ping] 2R]埃农吸引子 Henon attractor CN=O分岔 bifurcation ]分岔集 bifurcation set IB(ps)余维[数] co-dimension 55:叉式分岔 pitchfork bifurcation /N4<h)< p="">鞍结分岔 saddle-node bifurcation ,EYe9次级分岔 secondary bifurcation 9.[7?Y跨临界分岔 transcritical bifurcation 2$~GQ开折 unfolding c切分岔 tangent bifurcation D普适性 universality #g1`jL突变 catastrophe (db*G突变论 catastrophe theory $U=yTF折叠[型突变] fold [catastrophe] K"{ J尖拐[型突变] cusp [catastrophe] G+=\燕尾[型突变] swallow tail T}z:"e抛物脐[型突变] parabolic umbilic92t>1T双曲脐[型突变] hyperbolic umbilic o2sO椭圆脐[型突变] elliptic umbilic5e蝴蝶[型突变] butterfly .D阿诺德舌[头] Arnol'd tongue $$BZ反应 Belousov-Zhabotinski, reaction, BZ reaction Mp 法里序列 Farey sequence .cok法里树 Farey tree mE"洛特卡-沃尔泰拉方程 Lotka-V olterra equation +Pt梅利尼科夫积分 Mel'nikov integral S%锁频 frequency-locking TE{滞后[效应] hysteresis f"wm;突跳 jump &准周期振动 quasi-oscillation M=关闭窗口回首页</h)<></f^y<>。

基于肢体和微表情的多模态特征的抑郁倾向识别方法[发明专利]

(19)中华人民共和国国家知识产权局(12)发明专利申请(10)申请公布号 (43)申请公布日 (21)申请号 202010763656.4(22)申请日 2020.07.31(71)申请人华南理工大学地址 510640 广东省广州市天河区五山路381号(72)发明人杜广龙　(74)专利代理机构广州粤高专利商标代理有限公司 44102代理人何淑珍　江裕强(51)Int.Cl.G06K 9/00(2006.01)G06K 9/32(2006.01)G06K 9/62(2006.01)G06N 3/04(2006.01)G06N 3/08(2006.01)(54)发明名称基于肢体和微表情的多模态特征的抑郁倾向识别方法(57)摘要本发明公开了一种基于肢体和微表情的多模态特征的抑郁倾向识别方法。

所述方法包括以下步骤：借助非接触式测量传感器Kinect检测人体运动，生成运动文本描述；采用非接触式测量传感器Kinect捕捉人脸图像帧，对人脸感兴趣区域进行Gabor小波和线性判别分析，进行特征提取和降维，然后采用三层神经网络实现人脸表情分类，生成表情文本描述；通过一个具有自组织映射层的融合神经网络提取的文本描述进行融合并生成带有情感特征的信息；使用Softmax分类器将S3中生成的特征信息在情感类别中进行分类，分类结果用于评估该患者是否具有抑郁倾向。

本发明考虑到静态身体运动和动态身体运动，达到了更高的效率。

身体运动有助于识别抑郁症患者的情绪。

权利要求书3页说明书6页附图1页CN 111967354 A 2020.11.20C N 111967354A1.基于肢体和微表情的多模态特征的抑郁倾向识别方法，其特征在于，包括以下步骤：S1、借助非接触式测量传感器Kinect检测人体运动，分别采用卷积神经网络(CNN)和双向长短时记忆条件随机场(Bi-LSTM-CRF)对人体静态运动和动态运动进行分析，生成运动文本描述；S2、采用非接触式测量传感器Kinect捕捉人脸图像帧，对人脸感兴趣区域(ROI)进行Gabor小波和线性判别分析(LDA)，进行特征提取和降维，然后采用三层神经网络实现人脸表情分类，生成表情文本描述；S3、通过一个具有自组织映射层的融合神经网络对步骤S1和步骤S2中提取的文本描述进行融合并生成带有情感特征的信息；S4、使用Softmax分类器将S3中生成的特征信息在情感类别中进行分类，分类结果用于评估该患者是否具有抑郁倾向。

永磁同步电机鲁棒预测电流控制器设计

第55卷第2期2021年2月电力电子技术Power ElectronicsVol.55,No.2February2021永磁同步电机鲁棒预测电流控制器设计林茂李颖晖1,徐浩军1,查翔2(1.空军工程大学，陕西西安710038； 2.93802部队，陕西西安712200)摘要：预测控制器充分考虑了电力电子器件的非线性离散特性在有限范围内控制开关元器件工作，近年来成为应用到功率变换器和传动装置的热门控制方案。

预测控制器主要基于系统的数学模型进行预测，因此算法对系统参数精度要求较高，然而，实际交流传动系统中存在电感、电容等元器件参数随着系统的运行条件变化(如温度、磁路的饱和等因素)而发生改变，容易对算法造成负面影响。

此处考虑在许多模型参数存在不确定因素时，设计一种改进预测控制算法，对电流误差项进行补偿设计，降低参数不确定性对算法的影响，最后通过仿真实验对该控制方案的可行性进行验证。

关键词：永磁同步电机；预测控制；电流误差项中图分类号:TM351文献标识码：A文章编号:1000-100X(2021)02-0060-05Research on Robust Predictive Current Controller forPermanent Magnet Synchronous MotorsLIN Mao L2,LI Ying-hui1,XU Hao-Jun1,ZHA Xiang2(l.Air Force Engineering University,Xi*an710038,China)Abstract:In recent years,predictive controller becomes a hot control strategy appling to the power converter and transmission scheme,for it fully considering the nonlinear discrete characteristics of the power electronic devices and limited switch components within the scope of operation, predictive controller control method is mainly based on the mathematical model to control system,so the requirements of algorithm to the system parameters accuracy is higher. However,during the actual AC drive system, the parameters of the elements such as inductor, capacitor,resistance,as the system operating condition changes(such as temperature,magnetic circuit saturation,etc.)and change,it easy to lead a negative impact to the predictive controller algorithm.When model parameters are uncertain,an improved predictive control algorithm is designed to compensate current error term and reduce the influence of parameter uncertainty on the algorithm.Finally,the feasibility of the control scheme is verified through simulation experiment. Keywords:permanent magnet synchronous motors；predictive control；current error term1引言永磁同步电机(PMSM)调速系统中存在干扰及不确定因素，如随温度非线性变化的磁链、定子电阻和电感参数"等均会引起电机转矩脉动干扰和转动惯量变化。

非特异性描述讲课PPT课件

课件特点
非特异性：适用于多种场合和主题内容丰富：涵盖多个领域和知识点互动性强：鼓励学生参与和讨论易于理解：语言通俗易懂，便于学生理解
02
课件内容
课件结构
开场白：介绍课程内容、目的和预期效果主题介绍：详细讲解非特异性描述的概念、特点和应用案例分析：通过实际案例分析非特异性描述的应用和效果互动环节：提问、讨论和答疑，增强学员参与感和理解度总结回顾：总结课程要点，强调非特异性描述的重要性和实际应用结束语：感谢学员的参与，鼓励学员在实际工作中应用所学知识
内容概述
讲课目的：帮助学生理解非特异性描述的特点和应用
非特异性描述：一种描述方式，不具体到特定的事物或概念
讲课内容：包括非特异性描述的定义、特点、应用和实
例
讲课方法：采用案例分析、讨论和练习等方式进行讲解
重点难点
非特异性描述：理解非特异性描述的概念和特点
讲课技巧：掌握如何有效地进行非特异性描述讲课
制作流程
确定主题：明确课件的主题和目标
收集资料：搜集与主题相关的资料和素材
设计课件：设计课件的框架和结构，包括标题、内容、图片、动画等
制作课件：使用PPT或其他软件制作课件，注意排版、配色、字体等细节
测试课件：在正式使用前，进行多次测试，确保课件的稳定性和流畅性
修改完善：根据测试结果，对课件进行修改和完善，直至达到满意的效果
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课件使用
使用方法
打开PPT课件，点击“开始”按钮
选择“幻灯片放映” 选项，选择“从头开始”或“从当前幻灯片开始”
使用鼠标或键盘控制幻灯片切换，如点击鼠标左键或按空格键
使用鼠标或键盘控制幻灯片内容，如点击鼠标左键或按 Enter键

曲率无关方向扩散及改进型Chan-Vese主动轮廓模型

曲率无关方向扩散及改进型Chan-Vese主动轮廓模型一、引言1.1 研究背景和意义1.2 相关研究综述1.3 研究内容和方法二、曲率无关方向扩散2.1 常规方向扩散模型2.2 曲率无关方向扩散模型的原理和优点2.3 数值实现及实验结果分析三、Chan-Vese主动轮廓模型3.1 Chan-Vese模型的基本原理3.2 模型的优缺点分析3.3 修改型Chan-Vese主动轮廓模型提出及原理四、改进型Chan-Vese主动轮廓模型实验4.1 实验数据集及方法4.2 结果分析与对比4.3 模型评价及应用前景展望五、结论5.1 研究成果总结5.2 存在问题及未来工作展望5.3 对相关领域的启示和贡献注：上述提纲是一般模式的论文提纲，实际情况根据所选材料确定第一章：引言1.1 研究背景和意义图像处理技术在医学成像、工业检测、交通监控等领域应用广泛。

主动轮廓模型是图像处理中常用的技术之一，能够对图像中感兴趣的区域进行分割。

常规的主动轮廓模型使用曲率流方法对轮廓进行演化，但是这种方法容易出现边缘模糊或者断裂的问题，同时处理高曲率区域的精度较低。

曲率无关方向扩散模型是一种新的主动轮廓模型，它不仅可以保持边缘的清晰度，而且对高曲率区域的处理效果也很好。

因此，优化主动轮廓模型的方法成为图像处理研究的热点之一。

1.2 相关研究综述主动轮廓模型和曲率流方法已经被广泛研究和应用。

为了解决曲率流方法的问题，相继提出了很多曲率无关的方法，如全变分模型(Variational model)、水平集方法(Level-set method)和区域竞争模型(Region competition model)等。

这些方法在实际应用中有较好的效果，但是也存在一些问题，如计算量大、收敛速度慢等。

近年来，针对主动轮廓模型的不足之处，采用改进型的方法进行研究。

例如，针对区域竞争模型的计算量大的问题，提出了基于快速多分辨率分析的算法；针对全变分模型的边缘细化不明显，提出了可以减少计算量的全变分-动态正则化模型等。

Thermodynamic Validity of Noise Models for Nonlinear Resistive Devices

John L. Wyatt and Geo rey J. Coram
shot-noise amplitude for a class of nonlinear resistances. The noise behavior for equilibrium and nonequilibrium bias conditions is uniquely speci ed by the voltage-current relation and thermodynamic constraints. Secondly, we show that the Gaussian model cannot be applied to any nonlinear device. While the Gaussian model can be a useful approximation, it cannot be physically correct.
0
Poisson Device Models
where Nf and Nr are the homogeneous forward and reverse counting processes, and fT (v) and rT (v) the temperature-dependent forward and reverse rates, respectively. The average current is then ? ? i(t) = e fT v(t) ? rT v(t) ; which gives the constitutive relation for the device (i.e., the v ? i curve). Under dc bias conditions with constant v, the current random process i(t) becomes stationary and hence has a power spectral density. The spectrum is white 1] with magnitude Sii (!) = e2 fT (v) + rT (v)] ; 8!: (3) The analytical simplicity of this model comes from the three very strong assumptions that 1) the electron arrival is instantaneous and can therefore be modeled as a -function, 2) the system is memoryless, and 3) the expected rate changes instantaneously with v. Since the noise statistics are determined by the sum of the average currents while the constitutive relation is determined by the di erence, the development so far does not imply any unique relation between the constitutive relation and the noise. We will show that with the thermodynamic constraints a unique noise amplitude does exist for each operating voltage v.

ShannonandWeaverx27sCommunicationModel

Shannon and Weaver's Communication ModelVery well-known model of communication developed by Shannon and Weaver (1949), as the prototypical example of a transmissive model of communication: a model which reduces communication to a process of 'transmitting information*. The underlying metaphor of communication as transmission underlies 'commonsense' everyday usage but is in many ways misleading and repays critical attention.Shannon and Weaver's model is one which is，in John Fiske*s words, Xvidely accepted as one of the main seeds out of which Communication Studies has grown* (Fiske 1982: 6). Claude Shannon and Warren Weaver were not social scientists but engineers working for Bell Telephone Labs in the United States・ Their goal was to ensure the maximum efficiency of telephone cables and radio waves・ They developed a model of communication which was intended to assist in developing a mathematical theory of communication・Shannon and Weaver's work proved valuable for communication engineers in dealing with such issues as the capacity of various communication channels in 'bits per second*. It contributed to computer science・ It led to very useful work on redundancy in language・ And in making Information1 「measurable' it gave birth to the mathematical study of 'information theory*. However, these directions are not our concern here・ The problem is that some commentators have claimed that Shannon and Weavers model has a much wider application to human communication than a purely technical one・message messageC & W s original model consisted of five elements:1 ・ An information source, which produces a message.2. A transmitter, which encodes the message into signals3. A channel, to which signals are adapted for transmission4. A receiver, which 'decodes* (reconstructs) the message from the signal.5. A destination, where the message arrives・A sixth element, noise is a dysfunctional factor: any interference with the message travelling along the channel (such as 'static' on the telephone or radio) which may lead to the signal received being different from that sent.For the telephone the channel is a wire, the signal is an electrical current in it, and the transmitter and receiver are the telephone handsets・ Noise would include crackling from the wire・ In conversation, my mouth is the transmitter, the signal is the sound waves, and your ear is the receiver. Noise would include any distraction you might experience as I speak.Although in Shannon and Weaver's model a speaker and a listener would strictly be the source and the destination rather than the transmitter and the receiver, in discussions of the model the participants are commonly humanised as the sender and the receiver. My critical comments will refer less specifically to Shannon and Weaver's model than to the general transmission model which it reflects, where communication consists of a Sender passing a Message to a Receiver. So when I am discussing transmission models in general I too will refer to the participants as the Sender and the Receiver.Shannon and Weaver's transmission model is the best-known example of the 'informational' approach to communication. Although no serious communication theorist would still accept it, it has also been the most influential model of communication which has yet been developed, and it reflects a commonsense (if misleading) understanding of what communication is. Lasswcll's verbal version of this model: 'Who says what in which channel to whom with what effect ?* was reflected in subsequent research in human communication which was closely allied to behaviouristic approaches.Levels of problems in the analysis of coinmunicationShannon and Weaver argued that there were three levels of problems of communication:◊ A The technical problem: how accurately can the message be transmitted?◊ B The semantic problem: how precisely is the meaning Conveyed?◊ C The effectiveness problem: how effectively does the received meaning affect behaviour?Shannon and Weaver somewhat naively assumed that sorting out Level A problems would lead to improvements at the other levels・Although the concept of hoisc' does make some allowance for the way in which messages may be 'distorted*, this frames the issue in terms of incidental interference* with the sender's intentions rather than in terms of a central and purposive process of interpretation. The concept reflects Shannon and Weaver's concern with accuracy and efficiency.Advantages of Shannon and Weaver's modelParticular models are useful for some purposes and less useful for others. Like any process of mediation a model foregrounds some features and backgrounds others・ The strengths of Shannon and Weaver's model are its◊simplicity,◊generality, and◊quantifiabilit y.Such advantages made this model attractive to several academic disciplines .It also drew serious academic attention to human communication and information theory1, leading to further theory and research・Weaknesses of the transmission model of coininunicationThe transmission model is not merely a gross over-simplification but a dangerously misleading misrepresentation of the nature of human communication. This is particularly important since it underlies the 'commonsense' understanding of what communication is. Whilst such usage may be adequate for many everyday purposes, in the context of the study of media and communication the concept needs critical reframing.MetaphorsShannon and Weaver's highly mechanistic model of comnnmication can be seen as being based on a transport metaphor. James Carey (1989: 15) notes that in the nineteenth century the movement of information was seen as basically the same as the transport of goods or people, both being described as Communication*. Carey argues that *it is a view of communication that derives from one of the most ancient of human dreams: the desire to increase the speed and effect of messages as they travel in space' (ibid.) Writing always had to be transported to the reader, so in written communication the transport of letters, books and newspapers supported the notion of the transport of meaning from writer to readers. As Carey notes, The telegraph ended the identity but did not destroy the metaphof (ibid.).Within the broad scope of transport I tend to see the model primarily as employing a postal metaphor. It is as if communication consists of a sender sending a packet of information to a receiver, whereas I would insist that communication is about meaning rather than information. One appalling consequence of the postal metaphor for communication is the current reference to delivering the curriculum1in schools, as a consequence of which teachers are treated as postal workers・ But the influence of the transmission model is widespread in our daily speech when we talk of Conveying meaning1, getting the idea across1, transferring information*, and so on. We have to be very alert indeed to avoid falling into the clutches of such transmissive metaphors.Michael Reddy (1979) has noted our extensive use in English of 'the conduit metaphor in describing communicative acts・ In this metaphor, The speaker puts ideas (objects) into words (containers) and sends them (along a conduit) to a hearer who takes the idea/objects out of the word/containers1 (Lakoff & Johnson 1980: 10). The assumptions the metaphor involves are that:◊Language functions like a conduit, transferring thoughts bodily from one person to another;◊in writing and speaking, people insert their thoughts or feelings into the words;◊words accomplish the transfer by containing the thoughts or feelings and conveying them to others;◊in listening or reading, people extract the thoughts and feelings once again from the words. (Reddy 1979: 290)As Reddy notes, if this view of language were correct, learning would be effortless and accurate. The problem with this view of language is that learning is seen as passive, with the learner simply 'taking in* information (Bowers 1988: 42). I prefer to suggest that there is no information in language, in books or in any medium per se. If language and books do Contain* something, this is only words rather than information. In formation and meaning arises only in the process of listeners, readers or viewers actively making sense of what they hear or see・ Meaning is not Extracted*, but constmctecLIn relation to mass communication rather than interpersonal communication, key metaphors associated with a transmission model are those of the hypodermic needle and of the bullet. In the context of mass comnumication such metaphors are now largely used only as the targets of criticism by researchers in the field.LinearityThe transmission model fixes and separates the roles of 'sender* and 'receiver'・ But communication between two people involves simultaneous 'sending' and 'receiving' (not only talking, but also *body language1 and so on). In Shannon and Weaver's model the source is seen as the active decision-maker who determines the meaning of the message; the destination is the passive target.It is a linear, one-way model, ascribing a seconckuy role to the 'receiver； who is seen as absorbing infonnation・ However, communication is not a one-way street. Even when we are simply listening to the radio, reading a book or watching TV we are far more interpretively active than we nonnally realize・There was no provision in the original model for feedback (reaction from the receiver)・ Feedback enables speakers to adjust their performance to the needs and responses of their audience・ A Teedback loop* was added by later theorists, but the model remains linear・Content and meaningIn this model, even the nature of the content seems irrelevant, whereas the subject, or the way in which the participants feel about it, can shape the process of conimunication. Insofar as content has any place (typically framed as 'the message*), transmission models tend to equate content and meaning, whereas there may be varying degrees of divergence between the 'intended meaning* and the meanings generated by interpreters.According to Erik Meeuwissen (e-mail 26/2/98) Shannon himself was well aware of the fact that his theory did not address meaning・ He offers these supportive quotations from Shannon and Weaver:The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point. Frequently the messages have meaning that is they refer to or are correlated according to some system with certain physical or conceptual entities・ These semantic aspects of communication are irrelevant to the engineering problem (Shannon 1948).The word information, in this theory, is used in a special sense that must not be confused with its ordinary usage・ In particular, information must not be confused with meaning・ In fact, two messages, one of which is heavily loaded with meaning and the other of which is pure nonsense, can be exactly equivalent, from thepresent viewpoint, as regards information. It is this, undoubtedly, that Shannon means when he says that 'the semantic aspects of communication are irrelevant to the engineering aspects. (Weaver 1949)Weaver also noted that the theory...has so penetratingly cleared the air that one is now, perhaps for the first time, ready for a real theory of meaning・ An engineering communication theory is just like a very proper and discreet girl accepting your telegram・ She pays no attention to the meaning whether it be sad, or joyous, or embarrassing・ But she must be prepared to deal with all that come to her desk (Weaver 1949).However, the important point here is that meaning-making is not central in transmission models. It is widely assumed that meaning is contained in the 'message' rather than in its interpretation. But there is no single, fixed meaning in any message・We bring varying attitudes, expectations and understandings to communicative situations・ Even if the receiver sees or hears exactly the same message which the sender sent, the sense which the receiver makes of it may be quite different from the sender's intention・ The same 'message' may represent multiple meanings・ The word 'message1 is a sort of microcosm of the whole postal metaphor, so I'm not happy with even using that label.Transmission models treat decoding as a mirror image of encoding・ allowing no room for the receiver's inteipretative frames of reference・ Where the message is recorded in some form lenders* may well have little idea of who the Receivers' may be (particularly, of course, in relation to mass communication). The receiver need not simply accept, but may alternatively ignore or oppose a message・ We don't all necessarily have to accept messages which suggest that a particular political programme is good for us.InstrunientalismThe transmission model is an instrumental model in that it treats communication as a means to a predetermined end. Perhaps this is the way in which some people experience communication. However, not all communication is intentional: people unintentionally communicate a great deal about their attitudes simply through body language・ And, although this idea will sound daft to those who,ve never experienced it, when some of us write something, we sometimes find out what we want to say only after wc'vc finished writing about it.Some critics argue that this model is geared towards improving a communicators ability to manipulate a receiver. Carey notes that 'the centre of this idea of communication is the transmission of signals or messages over distance for the purposes of control... of distance and people* (Carey 1989: 15).In an instnimental framework the process involved is intended to be transparent1 to the participants (nothing is intended to distract from the sender's communicative goal)・ Such a conception is as fundamental to the rhetoric of science as it is alien to that of art. Perfectly transparent communication* is impossible・ContextNor is there any mention in the transmission model of the importance of context: situational, social, institutional, political, cultural, historical. Meaning cannot be independent of such contexts. Whilst recorded texts (such as letters in relation to interpersonal communication and newspapers, films, radio and television programmes in relation to mass communication) allow texts to be physically separated from their contextsof production. this is not to say that meaning can be Context-free*. Whilst it is true that meaning is not wholly 'determined* by contexts of production1 or deception' (texts do not mean simply what either their producers or their interpreters choose for them to mean), meanings may nevertheless be radically inflected by particular contexts of 'writing* and 'reading' in space and time・ The f same* text can be interpreted quite differently within different contexts.Social contexts have a key influence on what arc perceived as appropriate forms, styles and contents. Regarding situational context, it makes a lot of difference if the sender is an opinionated taxi-driver who drives aggressively, and the receiver is a passenger in the back seat whose primary concern is to arrive at the destination in one piece・Relationships and purposesIn the transmission model the participants are treated as isolated individuals. Contemporary communication theorists treat communication as a shared social system. We arc all social beings, and our communicative acts cannot be said to represent the expression of purely individual thoughts and feelings・ Such thoughts and feelings are socio-culturally patterned・ Even what we call ^ur* language isn*t our own: we are born into it; we can't change the rules・ Words have connotations which we don*t choose for them・ An emphasis on creative individuality is itself a culturally-shaped myth which had a historically 'modcnV origin in Western Europe・Transmission models of communication reduce human communication to the transmission of messages, whereas, as the linguists tell us, there is more to communication than this・ They refer, for instance, to phatic communication, which is a way of maintaining relationships• In Britain, talking about the weather is far more a matter of phatic communication than of transmitting information1・No allowance is made in the transmission model for differing purposes・ The same TV images of a football match would have very different meanings for the fans of opposing sides・In models such as Shannon and Weaver's no allowance is made for relationships between people as communicators (c.g. differences in power). We frame what is said differently according to the roles in which we communicate .If a friend asks you later what you thought of this lecture you are likely to answer in a somewhat different way from the way you might answer the same question from the undergraduate course director in his office・The interview is a very good example of the unequal power relationship in a communicative situation.People in society do not all have the same social roles or the same rights・ And not all meanings are accorded equal value.1( makes a difference whether the participants are of the same social class, gender, broad age group or profession. We need only think of whose meanings prevail in the doctor's surgery. And. more broadly; we all know that certain voices *carr}r more authority* than others, and that in some contexts, Children are to be seen and not heard*. The dominant directionality involved in communication cannot be fixed in a model but must be related to the situational distribution of power.TimeFurthermore, Shannon and Weaver's model makes no allowance for dynamic change over time. People don'tremain frozen in the same roles and relationships, with the same purposes・ Even within the course of a single conversation, such relationships may continuously shift・ Also, adopting a more 'historical' perspective, however stable the text may seem to be. the ways in which a recorded text may be interpreted depends also on circumstances at that time of its interpretation.MediumFinally, the model is indifferent to the nature of the medium. And yet whether you speak directly to, write to, or phone a lover, for instance, can have major implications for the meaning of your comnmnication. There are widespread social conventions about the use of one medium rather than another for specific purposes ・ People also differ in their personal attitudes to the use of particular media (e.g・ word processed Christmas circulars from friends!)・Furthermore, each medium has technological features which make it easier to use for some purposes than for others・ Some media lend themselves to direct feedback more than others. The medium can affect both the form and the content of a message・The medium is therefore not simply 'neutral' in the process of conimunication.ConclusionIn short .the transmissive model is of little direct value to social science research into human communication ・ and its endurance in popular discussion is a real liability. Its reductive influence has implications not only for the commonsense understanding of communication in general, but also for specific forms of communication such as speaking and listening, writing and reading, watching television and so on. In education, it represents a similarly transmissive model of teaching and learning・And in perception in general, it reflects the naive Yealist* notion that meanings exist in the world awaiting only decoding by the passive spectator. In all these contexts, such a model underestimates the creativity of the act of interpretation ・Alternatives to transmissive models of communication are normally described as constructivist: such perspectives acknowledge that meanings are actively constructed by both initiators and interpreters rather than simply 'transmitted*. However, you will find no single, widely-accepted constructivist model of communication in a form like that of Shannon and Weaver's block diagram. This is partly because those who approach communication from the constructivist perspective often reject the very idea of attempting to produce a formal model of communication. Where such models are offered・ they stress the centrality of the act of making meaning and the importance of the socio-cultural context.。

ChatGPT模型的无监督预训练方法

ChatGPT模型的无监督预训练方法在人工智能领域，自然语言处理一直是一个热门的研究方向。

最近，OpenAI发布的ChatGPT模型引起了广泛的关注。

ChatGPT模型是一种用于对话生成的预训练模型，它基于GPT-3模型的基础上进行了改进和优化。

本文将探讨ChatGPT模型的无监督预训练方法及其应用。

ChatGPT模型的无监督预训练方法是通过大规模的语料库进行训练。

与传统的监督学习不同，无监督学习不需要人工标注的训练数据，而是通过学习数据之间的内在结构和模式来提取信息。

ChatGPT模型利用了无监督学习的思想，通过阅读和理解大量的对话数据，学习到了语言的语法、语义和上下文依赖关系等信息。

ChatGPT模型的预训练分为两个阶段：自回归预训练和对话独立预训练。

首先，模型使用自回归的方式进行预训练。

自回归预训练是指让模型在给定一句话的情况下预测下一句话的内容。

通过这个过程，模型能够学习到语言的连贯性和生成对话的能力。

然后，在自回归预训练的基础上，模型进行对话独立预训练。

对话独立预训练是指让模型从一组对话中随机选择一条对话，并通过预测对话中的下一句话来学习对话的上下文依赖关系。

通过这两个阶段的预训练，ChatGPT模型能够更好地理解和生成自然语言对话。

ChatGPT模型在无监督预训练的基础上，还通过强化学习进行微调。

强化学习主要用于优化模型的生成能力和交互能力。

模型通过与人工智能代理进行对话来获取实时反馈，并根据反馈调整生成的对话内容。

这样，模型能够不断改进自身的生成能力，使对话更加符合人类的需求和习惯。

ChatGPT模型的无监督预训练方法不仅可以用于对话生成，还可以应用于其他自然语言处理任务。

比如，可以利用ChatGPT模型进行文本摘要、机器翻译、情感分析等任务。

通过微调的方式，模型可以在特定的任务上取得良好的效果。

然而，尽管ChatGPT模型的无监督预训练方法在自然语言处理领域取得了重要的突破，但仍然存在一些挑战和限制。

运动性肌肉疲劳

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