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[ToG13]Poisson Surface Reconstruction

Screened Poisson Surface ReconstructionMICHAEL KAZHDANJohns Hopkins UniversityandHUGUES HOPPEMicrosoft ResearchPoisson surface reconstruction creates watertight surfaces from oriented point sets.In this work we extend the technique to explicitly incorporate the points as interpolation constraints.The extension can be interpreted as a generalization of the underlying mathematical framework to a screened Poisson equation.In contrast to other image and geometry processing techniques,the screening term is deﬁned over a sparse set of points rather than over the full domain.We show that these sparse constraints can nonetheless be integrated efﬁciently.Because the modiﬁed linear system retains the sameﬁnite-element discretization,the sparsity structure is unchanged,and the system can still be solved using a multigrid approach. Moreover we present several algorithmic improvements that together reduce the time complexity of the solver to linear in the number of points, thereby enabling faster,higher-quality surface reconstructions.Categories and Subject Descriptors:I.3.5[Computer Graphics]:Compu-tational Geometry and Object ModelingAdditional Key Words and Phrases:screened Poisson equation,adaptive octree,ﬁnite elements,surfaceﬁttingACM Reference Format:Kazhdan,M.,and Hoppe,H.Screened Poisson surface reconstruction. ACM Trans.Graph.NN,N,Article NN(Month YYYY),PP pages.DOI=10.1145/XXXXXXX.YYYYYYY/10.1145/XXXXXXX.YYYYYYY1.INTRODUCTIONPoisson surface reconstruction[Kazhdan et al.2006]is a well known technique for creating watertight surfaces from oriented point samples acquired with3D range scanners.The technique is resilient to noisy data and misregistration artifacts.However, as noted by several researchers,it suffers from a tendency to over-smooth the data[Alliez et al.2007;Manson et al.2008; Calakli and Taubin2011;Berger et al.2011;Digne et al.2011].In this work,we explore modifying the Poisson reconstruc-tion algorithm to incorporate positional constraints.This mod-iﬁcation is inspired by the recent reconstruction technique of Calakli and Taubin[2011].It also relates to recent work in im-age and geometry processing[Nehab et al.2005;Bhat et al.2008; Chuang and Kazhdan2011],in which a dataﬁdelity term is used to“screen”the associated Poisson equation.In our surface recon-struction context,this screening term corresponds to a soft con-straint that encourages the reconstructed isosurface to pass through the input points.The approach we propose differs from the traditional screened Poisson formulation in that the position and gradient constraints are deﬁned over different domain types.Whereas gradients are constrained over the full3D space,positional constraints are introduced only over the input points,which lie near a2D manifold. We show how these two types of constraints can be efﬁciently integrated,so that we can leverage the original multigrid structure to solve the linear system without incurring a signiﬁcant overhead in space or time.To demonstrate the beneﬁts of screening,Figure1compares results of the traditional Poisson surface reconstruction and the screened Poisson formulation on a subset of11.4M points from the scan of Michelangelo’s David[Levoy et al.2000].Both reconstructions are computed over a spatial octree of depth10,corresponding to an effective voxel resolution of10243.Screening generates a model that better captures the input data(as visualized by the surface cross-sections overlaid with the projection of nearby samples), even though both reconstructions have similar complexity(6.8M and6.9M triangles respectively)and required similar processing time(230and272seconds respectively,without parallelization).1 Another contribution of our work is to modify both the octree structure and the multigrid implementation to reduce the time complexity of solving the Poisson system from log-linear to linear in the number of input points.Moreover we show that hierarchical point clustering enables screened Poisson reconstruction to attain this same linear complexity.2.RELA TED WORKReconstructing surfaces from scanned points is an important and extensively studied problem in computer graphics.The numerous approaches can be broadly categorized as follows. Combinatorial Algorithms.Many schemes form a triangula-tion using a subset of the input points[Cazals and Giesen2006]. Space is often discretized using a tetrahedralization or a voxel grid,and the resulting elements are partitioned into inside and outside regions using an analysis of cells[Amenta et al.2001; Boissonnat and Oudot2005;Podolak and Rusinkiewicz2005], eigenvector computation[Kolluri et al.2004],or graph cut [Labatut et al.2009;Hornung and Kobbelt2006].Implicit Functions.In the presence of sampling noise,a common approach is toﬁt the points using the zero set of an implicit func-tion,such as a sum of radial bases[Carr et al.2001]or piecewise polynomial functions[Ohtake et al.2005;Nagai et al.2009].Many techniques estimate a signed-distance function[Hoppe et al.1992; 1The performance of the unscreened solver is measured using our imple-mentation with screening weight set to zero.The implementation of the original Poisson reconstruction runs in412seconds.ACM Transactions on Graphics,V ol.VV,No.N,Article XXX,Publication date:Month YYYY.2•M.Kazhdan and H.HoppeFig.1:Reconstruction of the David head ‡,comparing traditional Poisson surface reconstruction (left)and screened Poisson surface reconstruction which incorporates point constraints (center).The rightmost diagram plots pixel depth (z )values along the colored segments together with the positions of nearby samples.The introduction of point constraints signiﬁcantly improves ﬁt accuracy,sharpening the reconstruction without amplifying noise.Bajaj et al.1995;Curless and Levoy 1996].If the input points are unoriented,an important step is to correctly infer the sign of the resulting distance ﬁeld [Mullen et al.2010].Our work extends Poisson surface reconstruction [Kazhdan et al.2006],in which the implicit function corresponds to the model’s indicator function χ.The function χis often deﬁned to have value 1inside and value 0outside the model.To simplify the derivations,inthis paper we deﬁne χto be 12inside and −12outside,so that its zero isosurface passes near the points.The function χis solved using a Laplacian system discretized over a multiresolution B-spline basis,as reviewed in Section 3.Alliez et al.[2007]form a Laplacian system over a tetrahedral-ization,and constrain the solution’s biharmonic energy;the de-sired function is obtained as the solution to an eigenvector prob-lem.Manson et al.[2008]represent the indicator function χusing a wavelet basis,and efﬁciently compute the basis coefﬁcients using simple local sums over an adapted octree.Calakli and Taubin [2011]optimize a signed-distance function to have value zero at the points,have derivatives that agree with the point normals,and minimize a Hessian smoothness norm.The resulting optimization involves a bilaplacian operator,which requires estimating derivatives of higher order than in the Laplacian.The reconstructed surfaces are shown to have good accuracy,strongly suggesting the importance of explicitly ﬁtting the points within the optimization.This motivated us to explore whether a Laplacian system could be extended in this respect,and also be compatible with a multigrid solver.Screened Poisson Surface Fitting.The method of Nehab et al.[2005],which simultaneously ﬁts position and normal constraints,may also be viewed as the solution of a screened Poisson equation.The ﬁtting algorithm assumes that a 2D parametric domain (i.e.,a plane or triangle mesh)is already established.The position and derivative constraints are both deﬁned over this 2D domain.In contrast,in Poisson surface reconstruction the 2D domain manifold is initially unknown,and therefore the goal is to infer an indicator function χrather than a parametric function.This leads to a hybrid problem with derivative (Laplacian)constraints deﬁned densely over 3D and position constraints deﬁned sparsely on the set of points sampled near the unknown 2D manifold.3.REVIEW OF POISSON SURFACE RECONSTRUCTIONThe approach of Poisson surface reconstruction is based on the observation that the (inward pointing)normal ﬁeld of the boundary of a solid can be interpreted as the gradient of the solid’s indicator function.Thus,given a set of oriented points sampling the boundary,a watertight mesh can be obtained by (1)transforming the oriented point samples into a continuous vector ﬁeld in 3D,(2)ﬁnding a scalar function whose gradients best match the vector ﬁeld,and (3)extracting the appropriate isosurface.Because our work focuses primarily on the second step,we review it here in more detail.Scalar Function Fitting.Given a vector ﬁeld V :R 3→R 3,thegoal is to solve for the scalar function χ:R 3→R minimizing:E (χ)=∇χ(p )− V (p ) 2d p .(1)Using the Euler-Lagrange formulation,the minimum is obtainedby solving the Poisson equation:∆χ=∇· V .System Discretization.The Galerkin formulation is used totransform this into a ﬁnite-dimensional system [Fletcher 1984].First,a basis {B 1,...,B N }:R 3→R is chosen,namely a collection of trivariate (usually triquadratic)B-spline functions.With respect to this basis,the discretization becomes:∆χ,B i [0,1]3= ∇· V ,B i [0,1]31≤i ≤Nwhere ·,· [0,1]3is the standard inner-product on the space of(scalar-and vector-valued)functions deﬁned on the unit cube:F ,G [0,1]3=[0,1]3F (p )·G (p )d p , U , V [0,1]3=[0,1]3U (p ), V (p ) d p .Since the solution is itself expressed in terms of the basis functions:χ(p )=N∑i =1x i B i (p ),ACM Transactions on Graphics,V ol.VV ,No.N,Article XXX,Publication date:Month YYYY .Screened Poisson Surface Reconstruction•3ﬁnding the coefﬁcients{x i}of the solution reduces to solving the linear system Ax=b where:A i j= ∇B i,∇B j [0,1]3and b i= V,∇B i [0,1]3.(2) The basis functions{B1,...,B N}are chosen to be compactly supported,so most pairs of functions do not have overlapping support,and thus the matrix A is sparse.Because the solution is expected to be smooth away from the input samples,the linear system is discretized byﬁrst adapting an octree to the input samples and then associating an(appropriately scaled and translated)trivariate B-spline function to each octree node. This provides high-resolution detail in the vicinity of the surface while reducing the overall dimensionality of the system.System Solution.Given the hierarchy deﬁned by an octree of depth D,a multigrid approach is used to solve the linear system. The basis functions are partitioned according to the depths of their associated nodes and,for each depth d,a linear system A d x d=b d is deﬁned using the corresponding B-splines{B d1,...,B d Nd},such thatχ(p)=∑D d=0∑i x d i B d i(p).Because the octree-selected B-spline functions do not form a complete grid at each depth,it is generally not possible to prolong the solution x d at depth d into the solution x d+1at depth d+1. (The B-spline associated with a given node is a sum of B-spline functions associated not only with its own child nodes,but also with child nodes of its neighbors.)Instead,the constraints at depth d+1are adjusted to account for the part of the solution already realized at coarser depths.Pseudocode for a cascadic solver,where the solution is only relaxed on the up-stroke of the V-cycle,is given in Algorithm1.Algorithm1:Cascadic Poisson Solver1For d∈{0,...,D}Iterate from coarse toﬁne2For d ∈{0,...,d−1}Remove the constraints3b d=b d−A dd x d met at coarser depths4Relax A d x d=b d Adjust the system at depth dHere,A dd is the N d×N d matrix used to transform solution coefﬁcients at depth d into constraints at depth d:A dd i j= ∇B d i,∇B d j [0,1]3.Note that,by deﬁnition,A d=A dd.Isosurface Extraction.Solving the Poisson equation,one obtains a functionχthat approximates the indicator function.Ideally,the function’s zero level-set should therefore correspond to the desired surface.In practice however,the functionχcan differ from the true indicator function due to several sources of error:—The point sampling may be noisy,possibly containing outliers.—The Galerkin discretization is only an approximation of the continuous problem.—The point sampling density is approximated during octree construction.To mitigate these errors,in[Kazhdan et al.2006]the implicit function is adjusted by globally subtracting the average value of the function at the input samples.4.INCORPORA TING POINT CONSTRAINTSThe original Poisson surface reconstruction algorithm adjusts the implicit function using a single global offset such that its average value at all points is zero.However,the presence of errors can cause the implicit function to drift so that no global offset is satisfactory. Instead,we seek to explicitly interpolate the points.Given the set of input points P with weights w:P→R≥0,we add to the energy of Equation1a term that penalizes the function’s deviation from zero at the samples:E(χ)=V(p)−∇χ(p) 2d p+α·Area(P)∑p∈P∑p∈Pw(p)χ2(p)(3)whereαis a weight that trades off the importance ofﬁtting the gradients andﬁtting the values,and Area(P)is the area of the reconstructed surface,estimated by computing the local sampling density as in[Kazhdan et al.2006].In our implementation,we set the per-sample weights w(p)=1,although one can also use conﬁdence values if these are available.The energy can be expressed concisely asE(χ)= V−∇χ, V−∇χ [0,1]3+α χ,χ (w,P)(4)where ·,· (w,P)is the bilinear,symmetric,positive,semi-deﬁnite form on the space of functions in the unit-cube,obtained by taking the weighted sum of function values:F,G (w,P)=Area(P)∑p∈P w(p)∑p∈Pw(p)·F(p)·G(p).4.1Interpretation as a Screened Poisson EquationThe energy in Equation4combines a gradient constraint integrated over the spatial domain with a value constraint summed at discrete points.As shown in the appendix,its minimization can be interpreted as a screened Poisson equation(∆−α˜I)χ=∇· V with an appropriately deﬁned operator˜I.4.2DiscretizationWe apply a discretization similar to that in Section3to the minimization of the energy in Equation4.The coefﬁcients of the solutionχwith respect to the basis{B1,...,B N}are again obtained by solving a linear system of the form Ax=b.The right-hand-side b is unchanged because the constrained value at the sample points is zero.Matrix A now includes the point constraints:A i j= ∇B i,∇B j [0,1]3+α B i,B j (w,P).(5) Note that incorporating the point constraints does not change the sparsity of matrix A because B i(p)·B j(p)is nonzero only if the supports of the two functions overlap,in which case the Poisson equation has already introduced a nonzero entry in the matrix.As in Section3,we solve this linear system using a cascadic multigrid algorithm–iterating over the octree depths from coarsest toﬁnest,adjusting the constraints,and relaxing the system.Similar to Equation5,the matrix used to transform a solution at depth d to a constraint at depth d is expressed as:A dd i j= ∇B d i,∇B d j [0,1]3+α B d i,B d j (w,P).ACM Transactions on Graphics,V ol.VV,No.N,Article XXX,Publication date:Month YYYY.4•M.Kazhdan and H.HoppeFig.2:Visualizations of the reconstructed implicit function along a planar slice through the cow ‡(shown in blue on the left),for the original Poisson solver,and for the screened Poisson solver without and with scale-independent screening.This operator adjusts the constraint b d (line 3of Algorithm 1)not only by removing the Poisson constraints met at coarser resolutions,but also by modifying the constrained values at points where the coarser solution does not evaluate to zero.4.3Scale-Independent ScreeningTo balance the two energy terms in Equation 3,it is desirable to adjust the screening parameter αsuch that (1)the reconstructed surface shape is invariant under scaling of the input points with respect to the solver domain,and (2)the prolongation of a solution at a coarse depth is an accurate estimate of the solution at a ﬁner depth in the cascadic multigrid approach.We achieve both these goals by adjusting the relative weighting of position and gradient constraints across the different octree depths.Noting that the magnitude of the gradient constraint scales with resolution,we double the weight of the interpolation constraint with each depth:A ddi j = ∇B d i ,∇B dj [0,1]3+2d α B d i ,B dj (w ,P ).The adaptive weight of 2d is chosen to keep the Laplacian and screening constraints around the surface in balance.To see this,assume that the points are locally planar,and consider the row of the system matrix corresponding to an octree node overlapping the points.The coefﬁcients of the system in that row are the sum of Laplacian and screening terms.If we consider the rows corresponding to the child nodes that overlap the surface,we ﬁnd that the contribution from the Laplacian constraints scales by a factor of 1/2while the contribution from the screening term scales by a factor of 1/4.2Thus,scaling the screening weights by a factor of two with each resolution keeps the two terms in balance.Figure 2shows the beneﬁt of scale-independent screening in reconstructing a cow model.The leftmost image shows a plane passing through the bounding cube of the cow,and the images to the right show the values of the computed indicator function along that plane,for different implementations of the solver.As the ﬁgure shows,the unscreened Poisson solver provides a good approximation of the indicator functions,with values inside (resp.outside)the surface approximately 1/2(resp.-1/2).However,applying the same solver to the screened Poisson equation (second from right)provides a solution that is only correct near the input samples and returns to zero near the faces of the bounding cube,2Forthe Laplacian term,the Laplacian scales by a factor of 4with reﬁnement,and volumetric integrals scale by a factor of 1/8.For the screening term,area integrals scale by a factor of 1/4.potentially resulting in spurious surface sheets away from the surface.It is only with scale-independent screening (right)that we obtain a high-quality solution to the screened Poisson ing this resolution adaptive weighting,our system has the property that the reconstruction obtained by solving at depth D is identical to the reconstruction that would be obtained by scaling the point set by 1/2and solving at depth D +1.To see this,we consider the two energies that guide the reconstruc-tion,E V (χ)measuring the extent to which the gradients of the so-lution match the prescribed vector ﬁeld,and E (w ,P )(χ)measuring the extent to which the solution meets the screening constraint:E V (χ)=V (p )−∇χ(p )2d p E (w ,P )(χ)=Area (P )∑p ∈P w (p )∑p ∈Pw (p )χ2(p ).Scaling by 1/2,we obtain a new point set (˜w ,˜P)with positions scaled by 1/2,unchanged weights,˜w (p )=w (2p ),and scaled area,Area (˜P )=Area (P )/4;a new scalar ﬁeld,˜χ(p )=χ(2p );and a new vector ﬁeld,˜ V (p )=2 V (2p ).Computing the correspondingenergies,we get:E ˜ V (˜χ)=1E V(χ)and E (˜w ,˜P )(˜χ)=1E (w ,P )(χ).Thus,scaling the screening weight by a factor of two with eachsuccessive depth ensures that the sum of energies is unchanged (up to multiplication by a constant)so the minimizer remains the same.4.4Boundary ConditionsIn order to deﬁne the linear system,it is necessary to deﬁne the behavior of the function space along the boundary of the integration domain.In the original Poisson reconstruction the authors imposed Dirichlet boundary conditions,forcing the implicit function to havea value of −12along the boundary.In the present work we extend the implementation to support Neumann boundary conditions as well,forcing the normal derivative to be zero along the boundary.In principle these two boundary conditions are equivalent for watertight surfaces,since the indicator function has a constant negative value outside the model.However,in the presence of missing data we ﬁnd Neumann constraints to be less restrictive because they only require that the implicit function have zero derivative across the boundary of the integration domain,a property that is compatible with the gradient constraint since the guiding vector ﬁeld V is set to zero away from the samples.(Note that when the surface does cross the boundary of the domain,the Neumann boundary constraints create a bias to crossing the domain boundary orthogonally.)Figure 3shows the practical implications of this choice when reconstructing the Angel model,which was only scanned from the front.The left image shows the original point set and the reconstructions using Dirichlet and Neumann boundary conditions are shown to the right.As the ﬁgure shows,imposing Dirichlet constraints creates a water-tight surface that closes off before reaching the boundary while using Neumann constraints allows the surface to extend out to the boundary of the domain.ACM Transactions on Graphics,V ol.VV ,No.N,Article XXX,Publication date:Month YYYY .Screened Poisson Surface Reconstruction•5Fig.3:Reconstructions of the Angel point set‡(left)using Dirichlet(center) and Neumann(right)boundary conditions.Similar results can be seen at the bases of the models in Figures1 and4a,with the original Poisson reconstructions obtained using Dirichlet constraints and the screened reconstructions obtained using Neumann constraints.5.IMPROVED ALGORITHMIC COMPLEXITYIn this section we discuss the efﬁciency of our reconstruction al-gorithm.We begin by analyzing the complexity of the algorithm described above.Then,we present two algorithmic improvements. Theﬁrst describes how hierarchical clustering can be used to re-duce the screening overhead at coarser resolutions.The second ap-plies to both the unscreened and screened solver implementations, showing that the asymptotic time complexity in both cases can be reduced to be linear in the number of input points.5.1Efﬁciency of basic solverLet us begin by analyzing the computational complexity of the unscreened and screened solvers.We assume that the points P are evenly distributed over a surface,so that the depth of the adapted octree is D=O(log|P|)and the number of octree nodes at depth d is O(4d).We also note that the number of nonzero entries in matrix A dd is O(4d),since the matrix has O(4d)rows and each row has at most53nonzero entries.(Since we use second-order B-splines, basis functions are supported within their one-ring neighborhoods and the support of two functions will overlap only if one is within the two-ring neighborhood of the other.)Assuming that the matrices A dd have already been computed,the computational complexity for the different steps in Algorithm1is: Step3:O(4d)–since A dd has O(4d)nonzero entries.Step4:O(4d)–since A d has O(4d)nonzero entries and the number of relaxation steps performed is constant.Steps2-3:∑d−1d =0O(4d)=O(4d·d).Steps2-4:O(4d·d+4d)=O(4d·d).Steps1-4:∑D d=0O(4d·d)=O(4D·D)=O(|P|·log|P|). There still remains the computation of matrices A dd .For the unscreened solver,the complexity of computing A dd is O(4d),since each entry can be computed in constant time.Thus, the overall time complexity remains O(|P|·log|P|).For the screened solver,the complexity of computing A dd is O(|P|)since deﬁning the coefﬁcients requires accumulating the screening contribution from each of the points,and each point contributes to a constant number of rows.Thus,the overall time complexity is dominated by the cost of evaluating the coefﬁcients of A dd which is:D∑d=0d−1∑d =0O(|P|)=O(|P|·D2)=O(|P|·log2|P|).5.2Hierarchical Clustering of Point ConstraintsOurﬁrst modiﬁcation is based on the observation that since the basis functions at coarser resolutions are smooth,it is unnecessary to constrain them at the precise sample locations.Instead,we cluster the weighted points as in[Rusinkiewicz and Levoy2000]. Speciﬁcally,for each depth d,we deﬁne(w d,P d)where p i∈P d is the weighted average position of the points falling into octree node i at depth d,and w d(p i)is the sum of the associated weights.3 If all input points have weight w(p)=1,then w d(p i)is simply the number of points falling into node i.This alters the computation of the system matrix coefﬁcients:A dd i j= ∇B d i,∇B d j [0,1]3+2dα B d i,B d j (w d,P d).Note that since d>d ,the value B d i,B d j (w d,P d)is obtained by summing over points stored with theﬁner resolution.In particular,the complexity of computing A dd for the screened solver becomes O(|P d|)=O(4d),which is the same as that of the unscreened solver,and both implementations now have an overall time complexity of O(|P|·log|P|).On typical examples,hierarchical clustering reduces execution time by a factor of almost two,and the reconstructed surface is visually indistinguishable.5.3Conforming OctreesTo account for the adaptivity of the octree,Algorithm1subtracts off the constraints met at all coarser resolutions before relaxing at a given depth(steps2-3),resulting in an algorithm with log-linear time complexity.We obtain an implementation with linear complexity by forcing the octree to be conforming.Speciﬁcally, we deﬁne two octree cells to be mutually visible if the supports of their associated B-splines overlap,and we require that if a cell at depth d is in the octree,then all visible cells at depth d−1must also be in the tree.Making the tree conforming requires the addition of new nodes at coarser depths,but this still results in O(4d)nodes at depth d.While the conforming octree does not satisfy the condition that a coarser solution can be prolonged into aﬁner one,it has the property that the solution obtained at depths{0,...,d−1}that is visible to a node at depth d can be expressed entirely in terms of the coefﬁcients at depth d−ing an accumulation vector to store the visible part of the solution,we obtain the linear-time implementation in Algorithm2.3Note that the weight w d(p)is unrelated to the screening weight2d introduced in Section4.3for scale-independent screening.ACM Transactions on Graphics,V ol.VV,No.N,Article XXX,Publication date:Month YYYY.6•M.Kazhdan and H.HoppeHere,P d d−1is the B-spline prolongation operator,expressing a solution at depth d−1in terms of coefﬁcients at depth d.The number of nonzero entries in P d d−1is O(4d),since each column has at most43nonzero entries,so steps2-5of Algorithm2all have complexity O(4d).Thus,the overall complexity of both the unscreened and screened solvers becomes O(|P|).Algorithm2:Conforming Cascadic Poisson Solver1For d∈{0,...,D}Iterate from coarse toﬁne.2ˆx d−1=P d−1d−2ˆx d−2Upsample coarseraccumulation vector.3ˆx d−1=ˆx d−1+x d−1Add in coarser solution.4b d=b d−A d d−1ˆx d−1Remove constraintsmet at coarser depths.5Relax A d x d=b d Adjust the system at depth d.5.4Implementation DetailsThe algorithm is implemented in C++,using OpenMP for multi-threaded parallelization.We use a conjugate-gradient solver to re-lax the system at each multigrid level.With the exception of the octree construction,most of the operations involved in the Poisson reconstruction can be categorized as operations that either“accu-mulate”or“distribute”information[Bolitho et al.2007,2009].The former do not introduce write-on-write conﬂicts and are trivial to parallelize.The latter only involve linear operations,and are par-allelized using a standard map-reduce approach:in the map phase we create a duplicate copy of the data for each thread to distribute values into,and in the reduce phase we merge the copies by taking their sum.6.RESULTSWe evaluate the algorithm(Screened)by comparing its accuracy and computational efﬁciency with several prior methods:the original Poisson reconstruction of Kazhdan et al.[2006](Poisson), the Wavelet reconstruction of Manson et al.[2008](Wavelet),and the Smooth Signed Distance reconstruction of Calakli and Taubin [2011](SSD).For the new algorithm,we set the screening weight toα=4and use Neumann boundary conditions in all experiments.(Numerical results obtained using Dirichlet boundaries were indistinguishable.) For the prior methods,we set algorithmic parameters to values recommended by the authors,using Haar Wavelets in the Wavelet reconstruction and setting the value/normal/Hessian weights to 1/1/0.25in the SSD reconstruction.For Poisson,SSD,and Screened we set the“samples-per-node”parameter to1and the “bounding-box-scale”parameter to1.1.(For Wavelet the bounding box scale is hard-coded at1and there is no parameter to adjust the sampling density.)6.1AccuracyWe run three different types of experiments.Real Scanner Data.To evaluate the accuracy of the different reconstruction algorithms on real-world data,we gathered several scanned datasets:the Awakening(10M points),the Stanford Bunny (0.2M points),the David(11M points),the Lucy(1.0M points), and the Neptune(2.4M points).For each dataset,we randomly partitioned the points into two equal-sized subsets:input points for the reconstruction algorithms,and validation points to measure point-to-reconstruction distances.Figure4a shows reconstructions results for the Neptune and David models at depth10.It also shows surface cross-sections overlaid with the validation points in their vicinity.These images reveal that the Poisson reconstruction(far left),and to a lesser extent the SSD reconstruction(center left),over-smooth the data,while the Wavelet reconstruction(center left)has apparent derivative discontinuities.In contrast,our screened Poisson approach(far right)provides a reconstruction that faithfullyﬁts the samples without introducing noise.Figure4b shows quantitative results across all datasets,in the form of RMS errors,measured using the distances from the validation points to the reconstructed surface.(We also computed the maximum error,but found that its sensitivity to individual outlier points made it an unreliable and unindicative statistic.)As theﬁgure indicates,the Screened Poisson reconstruction(blue)is always more accurate than both the original Poisson reconstruction algorithm(red)and the Wavelet reconstruction(purple),and generates reconstruction whose RMS errors are comparable to or smaller than those of the SSD reconstruction(green).Clean Uniformly Sampled Data.To evaluate reconstruction accuracy on clean data,we used the approach of Osada et al.[2001] to generate oriented point sets by uniformly sampling the surfaces of the Fandisk,Armadillo Man,Dragon,and Raptor models.For each model,we generated datasets of100K and1M points and reconstructed surfaces from each point set using the four different reconstruction algorithms.As an example,Figure5a shows the reconstructions of the fandisk and raptor models using1M point samples at depth10.Despite the lack of noise in the input data,the Wavelet reconstruction has spurious high-frequency detail.Focusing on the sharp edges in the model,we also observe that the screened Poisson reconstruction introduces less smoothing,providing a reconstruction that is truer to the original data than either the original Poisson or the SSD reconstructions.Figure5b plots RMS errors across all models,measured bidirec-tionally between the original surface and the reconstructed surface using the Metro tool[Cignoni and Scopigno1998].As in the case of real scanner data,screened Poisson reconstruction always out-performs the original Poisson and Wavelet reconstructions,and is comparable to or better than the SSD reconstruction. Reconstruction Benchmark.We use the benchmark of Berger et al.[2011]to evaluate the accuracy of the algorithms under different simulations of scanner error,including nonuniform sampling,noise,and misalignment.The dataset consists of mul-tiple virtual scans of implicit surfaces representing the Anchor, Dancing Children,Daratech,Gargoyle,and Quasimodo models. As an example,Figure6a visualizes the error in the reconstructions of the anchor model from a virtual scan consisting of210K points (demarked with a dashed rectangle in Figure6b)at depth9.The error is visualized using a red-green-blue scale,with red signifyingACM Transactions on Graphics,V ol.VV,No.N,Article XXX,Publication date:Month YYYY.。

莫西侧链的检测方法

盐酸莫西沙星侧链1. 质量指标：1、外观无色至淡红、浅棕色的油状液体到半固体2、鉴别在含量测定(GC)条件下, 样品主峰的保留时间应与对照品主峰的保留时间一致。

3、纯度（by GC），% ≥99.04、滴定含量，% ≥98.04 、水分，（by KF），% ≤0.56、比旋光度，（20℃）-2.5°~ -3.5 °2. 检测方法2.1 性状2.1.外观：无色至浅棕色的油状液体到半固体2.2 鉴别在适当的气相色谱条件下，供试品主峰的保留时间应与对照品主峰的保留时间一致2.3 气相含量2.3.1 仪器与用具：气相色谱仪色谱工作站微量进样器2.3.2 原理：以AT-5 为固定液的毛细管柱分离样品中各组分，用FID检测器检测，以面积归一法计算各组分的含量。

2.3.3 色谱条件：气相色谱仪：气相色谱仪及相应的色谱工作站色谱柱：SPB-5 30m×0.53mm×1.5μm 或相似色谱柱检测器：FID 空气流速：300～400ml/min载气：高纯氮气氢气流速：30～40ml/min进样方式：分流进样气化室温度：250℃进样量：0.1μl 检测器温度：270℃检测灵敏度：101 柱前压：0.04Mpa柱箱温度：初始温度：80℃，初始时间5min，升温速率8℃/min，终止时间200℃，终止时间15min。

计算方法：面积归一法操作时的色谱条件也可由使用者灵活选择，应得到合适的分离度22.3.4 测定方法：气相色谱启动后，进行一次程序空升以确定没有残留的外来杂质，取样品与乙醇体积比为1：1 配成的待测液0.1μl进入色谱系统同时启动程序升温采集图谱，待采样结束以面积归一法(扣除乙醇峰面积)计算各峰的峰面积，以百分含量表示。

2.4 含量测定2.4.1 试剂与试液：酚酞指示液：取酚酞1g，加乙醇100ml使溶解，即得。

盐酸滴定液（0.1mol/L）2.4.2 仪器与用具：锥形瓶（150ml）量筒（100ml）电子天平（万分之一）滴定管（50ml）2.4.3 测定方法：精密称取本品0.3g，加水100ml 使溶解，加酚酞指示液2~3 滴，用盐酸滴定液（0.1mol/L）滴定至无色，并将滴定的结果用空白试验校正，每1ml 盐酸滴定液（0.1mol/L）相当于12.6mg的C7N2H9。

迈克尔逊莫雷实验英语版

迈克尔逊莫雷实验英语版摘要：I.实验背景与目的- 迈克尔逊莫雷实验的起源- 实验的目的：验证以太是否存在II.实验装置与过程- 迈克尔逊干涉仪的构成- 实验的具体操作过程III.实验结果与分析- 实验观察到的干涉条纹- 基于干涉条纹的分析：以太风的假设- 洛伦兹等人的相对论解释IV.实验的意义与影响- 实验对以太理论的质疑- 实验对物理学发展的贡献：狭义相对论的提出正文：迈克尔逊莫雷实验是一个著名的物理学实验，始于19 世纪末，由迈克尔逊和莫雷两位科学家合作完成。

该实验旨在验证以太是否存在，以太是当时科学界普遍认为存在的一种物质，它是一种无所不在的、绝对静止的介质。

实验的装置由迈克尔逊干涉仪构成，它包括一个光源、一个分光镜、一个半反射镜和一个接收屏。

实验过程如下：首先，将光源发出的光经过分光镜分成两束，一束光照射到半反射镜上，另一束光照射到接收屏上。

然后，将接收屏上的光再次经过半反射镜反射，与照射到半反射镜上的光合并。

最后，在接收屏上观察到的干涉条纹进行分析。

实验结果表明，无论光源与接收屏如何移动，干涉条纹都没有发生变化。

这个结果让科学家们非常惊讶，因为按照当时的以太理论，当光源与接收屏移动时，干涉条纹应该发生变化。

为了解释这个现象，科学家们提出了以太风的假设，即以太在真空中流动，其流动速度与光源和接收屏的速度无关。

然而，这个假设并没有得到证实。

后来，洛伦兹等科学家提出了狭义相对论，认为光速是恒定的，与光源和接收屏的速度无关。

这个理论解释了迈克尔逊莫雷实验的结果，并成为了现代物理学的基础。

总之，迈克尔逊莫雷实验对以太理论提出了质疑，促使科学家们重新思考光的传播机制。

Celestron EdgeHD 1100 0.7x Reducer Lens Instructio

Figure 1 – Optimum Spacing for EdgeHD 9.25/11/14Instruction Manual – Model #94241.7x Reducer Lens – EdgeHD 1100Your .7x reducer lens makes your EdgeHD 1100 telescope onefull F-Stop faster than at f/10. Photographically this will enable youto reduce your exposure times by one-half and still capture thesame amount of light, while providing a 43% wider ﬁ eld of view.Celestron LLC • 2835 Columbia Street • Torrance, CA 90503Phone: 310.328.9560 • Fax: 310.212.5835©2012 Celestron • All rights reserved. #94241-INST 08-12Warranty: Two year limited warranty.For complete warranty details contact Celestron or visit: Attaching the Reducer 1. Remove the visual back and adapter plate from the rear of the telescope.2. The focal reducer threads directly onto the rear bafﬂ e locknut (see Figure 1) of your EdgeHD telescope.3. Attach your T-Adapter (#93646, sold separately) onto the rear threads of the focal reducer.Camera SpacingSince the optimal photographic back focus of 146 mm is thesame with or without the focal reducer attached, the optional #93646 T-Adapter can be used to attach the Nightscape CCD Camera, DSLR body or any other camera with 55 mm of back focus.For best performance, it is highly recommended that you position your camera as close to the recommended optimalspacing as possible. It is best to maintain optimal spacingto within 1-3 mm depending on the size of your imagingsensor. As your imaging chip gets larger (farther off-axis), maintaining optimal spacing becomes more critical. Being inside of focus (too short) tends to affect the outermost edgeof the ﬁ eld of view when using a relatively large sensor(17 mm or greater). Being outside of focus (too long) tendsto produce elongated star images towards the edge and could run the risk of running out of focus travel on yourEdgeHD optical tube. In general it is better to be slightly inside of focus than outside of focus.Focal lengths for the EdgeHD 1100 in its native format (f/10), with the .7x Reducer Lens and with optional f/2lens assembly.。

代数英语

(0,2) 插值||(0,2) interpolation0#||zero-sharp; 读作零井或零开。

0+||zero-dagger; 读作零正。

1-因子||1-factor3-流形||3-manifold; 又称“三维流形”。

AIC准则||AIC criterion, Akaike information criterionAp 权||Ap-weightA稳定性||A-stability, absolute stabilityA最优设计||A-optimal designBCH 码||BCH code, Bose-Chaudhuri-Hocquenghem codeBIC准则||BIC criterion, Bayesian modification of the AICBMOA函数||analytic function of bounded mean oscillation; 全称“有界平均振动解析函数”。

BMO鞅||BMO martingaleBSD猜想||Birch and Swinnerton-Dyer conjecture; 全称“伯奇与斯温纳顿－戴尔猜想”。

B样条||B-splineC*代数||C*-algebra; 读作“C星代数”。

C0 类函数||function of class C0; 又称“连续函数类”。

CA T准则||CAT criterion, criterion for autoregressiveCM域||CM fieldCN 群||CN-groupCW 复形的同调||homology of CW complexCW复形||CW complexCW复形的同伦群||homotopy group of CW complexesCW剖分||CW decompositionCn 类函数||function of class Cn; 又称“n次连续可微函数类”。

Cp统计量||Cp-statisticC。

基于边缘检测的抗遮挡相关滤波跟踪算法

基于边缘检测的抗遮挡相关滤波跟踪算法唐艺北方工业大学北京 100144摘要：无人机跟踪目标因其便利性得到越来越多的关注。

基于相关滤波算法利用边缘检测优化样本质量，并在边缘检测打分环节加入平滑约束项，增加了候选框包含目标的准确度，达到降低计算复杂度、提高跟踪鲁棒性的效果。

利用自适应多特征融合增强特征表达能力，提高目标跟踪精准度。

引入遮挡判断机制和自适应更新学习率，减少遮挡对滤波模板的影响，提高目标跟踪成功率。

通过在OTB-2015和UAV123数据集上的实验进行定性定量的评估，论证了所研究算法相较于其他跟踪算法具有一定的优越性。

关键词：无人机目标追踪相关滤波多特征融合边缘检测中图分类号：TN713;TP391.41;TG441.7文献标识码：A 文章编号：1672-3791(2024)05-0057-04 The Anti-Occlusion Correlation Filtering Tracking AlgorithmBased on Edge DetectionTANG YiNorth China University of Technology, Beijing, 100144 ChinaAbstract: For its convenience, tracking targets with unmanned aerial vehicles is getting more and more attention. Based on the correlation filtering algorithm, the quality of samples is optimized by edge detection, and smoothing constraints are added to the edge detection scoring link, which increases the accuracy of targets included in candi⁃date boxes, and achieves the effects of reducing computational complexity and improving tracking robustness. Adap⁃tive multi-feature fusion is used to enhance the feature expression capability, which improves the accuracy of target tracking. The occlusion detection mechanism and the adaptive updating learning rate are introduced to reduce the impact of occlusion on filtering templates, which improves the success rate of target tracking. Qualitative evaluation and quantitative evaluation are conducted through experiments on OTB-2015 and UAV123 datasets, which dem⁃onstrates the superiority of the studied algorithm over other tracking algorithms.Key Words: Unmanned aerial vehicle; Target tracking; Correlation filtering; Multi-feature fusion; Edge detection近年来，无人机成为热点话题，具有不同用途的无人机频繁出现在大众视野。

A comparative study of adhesion test methods for hard coatings

Surface and Coatings Technology 113(1999)86–102A comparative study of adhesion test methods for hard coatingsH.Ollendorf 1,D.Schneider *Fraunhofer Institut fu ¨r Werksto ﬀ-und Strahltechnik,Winterbergstraße 28,01277Dresden,GermanyReceived 17July 1998;accepted 25November 1998AbstractThe feasibility of seven techniques for testing and evaluating the adhesion of thin ﬁlms was investigated:scratch test,four-pointbending test,Rockwell test,cavitation test,impact test,laser-acoustics and acoustic microscopy.The studies were performed with TiN ﬁlms (thickness 1.2–2.45m m)deposited on the annealed steel 42CrMo4.The adhesion of the TiN ﬁlms was varied by varying the time of pre-sputtering the steel substrate with argon ions before the ﬁlm deposition.Argon pre-sputtering for 15min is recommended to guarantee an optimal adhesion.The pre-sputtering time,t S,was reduced down to 0.5min to reduce the adhesion.The following test parameters were used to evaluate the adhesion:the friction work,acoustic emission activity and critical load of the scratch test,the critical strain and the defect density of the four-point bending test,the proportional damage area of cavitation test,the critical number of loading cycles of the impact test,and Young’s modulus of the ﬁlm measured with the laser-acoustic method.These test parameters were examined for any correlation with the pre-sputtering time,t S.The results aresummarized in a table that shows which test methods and test parameters yield corresponding and contradictory evaluations of the ﬁlm quality.The e ﬀect of defect density and residual stresses is ser-acoustics and acoustic microscopy are non-destructive methods.Young’s modulus,as measured by laser-acoustics,is sensitive to the density of micro-defects.This is expected to indicate their e ﬀect on the adhesion.©1999Elsevier Science S.A.All rights reserved.Keywords:Adhesion;Bending test;Cavitation test;Impact test;Laser-acoustics;Scratch test;TiN ﬁlms1.Introductionthe nature of the bonds between the atoms of both materials.The ‘‘practical adhesion’’does not only Testing the adhesion of thin ﬁlms is one of the most depend on the ‘‘basic adhesion’’.This refers to the important and di ﬃcult tasks of surface engineering.It failure of hard coatings for wear protection,which is already di ﬃcult to ﬁnd a generally acceptable deﬁni-depends on a complex combination of the elastic proper-tion of adhesion between ﬁlm and substrate that takes ties and fracture toughness of the ﬁlm and substrate,the complexity of the e ﬀects of the material microstruc-the size distribution of ﬂaws,pores and other lattice ture,the external loading and the environmental aspects defects,the loading conditions and the friction behavior into account.The terms ‘‘basic adhesion’’and ‘‘practical against impacting or scraping particles and components adhesion’’were introduced to distinguish between study-[3].Therefore,surface engineering is interested in evalu-ing the fundamental physical aspects of the adhesion ating the ‘‘practical adhesion’’.Several methods are phenomenon and developing practically relevant test used,such as the scratch test,bending test,impact test,procedures for classifying the quality of a coating [1,2].cavitation test,and Rockwell imprint test.However,‘‘Basic adhesion’’is understood to be the summation of sometimes they provide contradictory results.all interatomic interactions at the interface of the ﬁlm An extensive test program was performed with TiN and substrate.This can be quantiﬁed as the work ﬁlms on steel to study the feasibility of these test necessary for completely separating the ﬁlm and sub-methods.TiN ﬁlms with di ﬀerent levels of adhesion to strate along the interface,excluding all e ﬀects other thanthe steel surface were prepared by ion plating.The adhesion was varied by varying the pre-sputtering time with argon ions.It is known that pre-sputtering a steel *Corresponding author.Tel:+493512583451;Fax:+493512583310;surface for 15min guarantees a good adhesion of TiN e-mail:schneider@iws.fhg.de[4].Seven test series with a total of 130samples were 1Present address:White Oak Semiconductor,6000Technology Blvd.,Sandston,VA 23150,USA.prepared with pre-sputtering times from t S=0.5to0257-8972/99/$–see front matter ©1999Elsevier Science S.A.All rights reserved.PII S0257-8972(98)00827-587H.Ollendorf,D.Schneider /Surface and Coatings Technology 113(1999)86–10215min.The test parameters of the adhesion tests were 2.2.Varying the ﬁlm adhesionexamined for any correlation with the pre-sputtering time,t S.The parameters are plotted versus the logarithmTiN ﬁlms with a thickness of 1.2–2.4m m were depos-ited by ion plating on the surface of the 42CrMo4of t Ssince the e ﬀect of the pre-sputter process on theadhesion reduces with increasing time,t S.samples by ion plating.The adhesion was varied by using di ﬀerent pre-sput-The ﬁlm quality was additionally characterized by Auger spectroscopy,hardness measurements and X-ray tering times,t S,(with plasma gas:argon).A series ofsamples series with pre-sputtering times of t S=0.5,1,2,texture investigations.It is desirable to evaluate the ﬁlm adhesion non-3,5and 15min was prepared.The best ﬁlm adhesion was expected for t S=15min and the worst adhesion fordestructively.Acoustic microscopy has shown to be able to detect interface imperfections and microscopic ﬂaws t S=0.5min.Since the improvement in adhesion is known to saturate with pre-sputtering time,the [5]and was involved in the test program.Surface acoustic waves are a promising non-destruc-increment of t Swas increased.The greatest improvementin adhesion is expected for shorter pre-sputtering times,tive method for characterizing thin ﬁlms and near-surface regions.High-frequency elastic vibrations propa-t S,but the pre-sputtering e ﬀect reduces with increasing t S .A maximum time of t S =15min is recommended for gate along the surface and allow Young’s moduli of the thin ﬁlms and substrates to be measured.Young’s modu-the ion-plating process used.The technology for depositing TiN ﬁlms with di ﬀerent lus represents the sti ﬀness of the material,which in turn depends on the average bonding strength in the tested adhesion is shown schematically in Fig.1.Two reference specimens with t S=15min have been additionally pre-material volume.It is also inﬂuenced by the defect density.A certain amount of microscopic pores and pared in each deposition run to identify the variations in stoichiometry of the ﬁlm which could accompany the micro-cracks can drastically reduce the modulus [6].Surface acoustic waves of a suitable frequency range adhesion e ﬀect.This was done by covering the samples intended for poorer adhesion with an aluminum foil in penetrate through the ﬁlm and interface into the sub-strate and,therefore,can be expected to detect a reduced the ﬁrst-phase t Pof the pre-sputtering process.Therefore,only the surfaces of the two reference samples strength of the interface caused by defects and lattice imperfections [7].Defects in both the brittle ﬁlm and were cleaned by argon etching during t P.Afterwards,the aluminum foils were removed from the protected the interface can be origins of the failure of the ﬁlm–-substrate composite.The Young modulus of the TiN samples,and both the reference samples and the test samples were argon-sputtered.The pre-sputtering timeﬁlms was measured with a laser-acoustic technique that enables variations in ﬁlm modulus of less than ±2.5%to be detected [8].Empirical correlations of the ﬁlm modulus with the results of the adhesion tests wereinvestigated.These correlations enable the ﬁlms to be non-destructively tested and improve the interpretation of the adhesion tests.The results of all tests are summarized in Table 1to evaluate the feasibility of the methods and to show agreements and contrasts.A discussion of the e ﬀects of di ﬀerent aspects of the adhesion behavior on the test results closes the article.2.Test material,preparation and characterization 2.1.Substrate preparationThe steel 42CrMo4steel was used as a substrate material.The samples had dimensions of 6×8×60mm,which were determined by the requirements of the four-point bending test.Before the ﬁlm deposition,the steel samples were quenched and tempered to a hardness of 350HV.The surface was polished to a roughness,R a,Fig.1.Simultaneous deposition of TiN ﬁlms with poor and good adhe-of 0.05m m.Afterwards,the samples were annealed at sion (reference samples)with di ﬀerent times,t S,of pre-sputtering withargon ions.560°C in vacuum so as to become stress-free.88H.Ollendorf,D.Schneider /Surface and Coatings Technology 113(1999)86–102of the test samples is determined by t S =15min −t P.After ﬁnishing the pre-sputtering process,the TiN ﬁlms coating was deposited on all samples with the same process parameters.In this way,ﬁlms with a good and poor adhesion could be deposited simultaneously.The quality of the test series was checked by measuring the Young modulus of the reference sample coatings.2.3.Controlling the ﬁlm qualityIt is known that the Young modulus of TiN sensitively depends on the stoichiometry [9].Therefore,the laser-acoustic method was used to check the ﬁlm quality of the reference samples of each test series.This could not Fig.3.Data record of the Scratch test showing the friction force,F F,be carried out on test samples with a lower pre-sputtering and acoustic emission events with increasing load,L N,for a ﬁlm withtime,t S,since the reduced adhesion is expected tot S=1min.inﬂuence the Young modulus.An introductory test series prepared with t S=15mincontents have been found within the interface region of showed an elastic modulus of E =435±5GPa for samples with t S=0.5min,which did not occur in thesamples with a good adhesion and stoichiometric com-reference samples with t S=15min.This result impliesposition.Higher ﬁlm moduli were not measured.that the sputtering treatment has the expected inﬂuence Therefore,this value was used as the threshold.on adhesion.This procedure should ensure that no e ﬀects other The hardness of the ﬁlm material was measured by than varying the ﬁlm adhesion inﬂuenced the results of the micro-indentation method (Shimadzu DUH 202)the mechanical tests.with a load of 1g.The values of 2100±300DHV are in agreement with those given in the literature.2.4.Characterizing the ﬁlmsThe micro-indentation tests were not su ﬃciently sensi-tive to determine the quality of the di ﬀerent test series.The textures of 12TiN ﬁlms were investigated by The ﬁlm thickness was determined by the X-ray X-ray di ﬀraction.A weak [111]texture was found ﬂuorescence technique (Fischerscope X-Ray 1020).A (already known for TiN ﬁlms deposited with moderate measuring uncertainty of D d /d ≤±0.02was achieved by ion PVD processes like ion plating [10]).careful calibration and a counting time of 5min.Eleven samples with pre-sputtering times of t S=0.5,2,5and 15min were investigated by Auger spectroscopy.Examples of Auger depth proﬁles are shown in Fig.2 3.Results for two pre-sputtered samples (t S=0.5and 15min).They reveal that the TiN ﬁlms have a stoichiometric 3.1.Scratch testcomposition.Slightly enhanced carbon and oxygenThe tests were performed with a Rockwell-shaped diamond indentor continuously loaded with a normal force,FN,from 0to 70N [11].The transverse velocityof the sample to the diamond was 10mm min −1,and the loading rate,d F N/d x =10N mm −1.The scratcheswere 7mm long.The friction force,F F,and the acousticemission signals were recorded.A typical data record is shown in Fig.3.The following test parameters were deduced from the scratch test:$critical load deduced from microscopic evaluation of the crack pattern around the scratch;$friction work along the scratch;$total number of acoustic emission signals in the scratch test;$critical load deduced from the Weibull statistical distribution of the ﬁrst acoustic emission signals in a Fig.2.Auger depth proﬁles for two samples pre-sputtered for t S=0.5and 15min,respectively.series of 20scratch tests;89H.Ollendorf,D.Schneider /Surface and Coatings Technology 113(1999)86–102$critical load deduced from the Weibull statistical su ﬃciently sensitive to distinguish between the other adhesion states.No signiﬁcant correlation between criti-distribution of the acoustic emission signals in one scratch test.cal load and pre-sputtering time was found.3.1.1.E v aluating the crack pattern3.1.2.Friction workFig.4shows two micrographs of scratches on samples The friction of the Rockwell diamond against the with a pre-sputtering time of t S=0.5and 15min.Thesample increased during the scratch test when the dia-sample pre-sputtered for 0.5min shows typical cracks mond removed the TiN ﬁlm from the steel substrate.and detachments in the form of chipping [12,13].The Fig.5shows the friction force,F F,versus the normalcoating material was not chipped away for samples pre-load on the stylus,F N,for two samples under di ﬀerentsputtered for 15min.Here,cracks are visible on either pre-sputtering times,t S.As long as the Rockwell dia-side of the scratch trace.Detailed experiments showed mond scratches the TiN ﬁlm,the friction force F Fisthat these cracks occurred coincidentally with the acous-identical for both samples with t S=2and 15min.In thetic signals [14].range of the breakthrough of the ﬁlm,F Fincreases moreRaster electron microscopic investigations conﬁrmed for the sample with t S=2min.This suggests that thethat light microscopic observations allowed a reliable area under the curve should be used as a test parameter detection of the ﬁrst ﬁlm detachments around the scratch for the adhesion.It is deﬁned as the friction work:trace.The test criteria proposed by Burnett and Rickerby [15]were used to determine the critical load of the ﬁlm detachment.The method revealed the lower W F=P F F d x =PF F /d FN d x d F N .(1)adhesion of the test series with t S=0.5min,but was not(a)(b)Fig.4.Light microscopic micrographs of scratches on samples with di ﬀerent pre-sputtering:(a)t S =15min;(b)t S=0.5min.90H.Ollendorf,D.Schneider /Surface and Coatings Technology 113(1999)86–1023.1.3.Acoustic emission acti v ityThe acoustic emission signals detected during the scratch test were ascribed to brittle micro-fractures in the TiN ﬁlm or the interface.The frequency of these events seems to be related to the defect density.Therefore,the number of acoustic emission events,N AE,is used as a test parameter for the adhesion.Fig.7shows the correlations of N AEwith the pre-sputteringtime,t S,for the three di ﬀerent classes of ﬁlm thickness.The acoustic emission activity,N AE,reduces withincreasing pre-sputtering time,t S,and shows the samebehavior as the friction work,W F,in Fig.6.Thiscorresponds to the assumption that the defect density is lower in samples produced under a longer pre-sputtering time.Signiﬁcant correlation coe ﬃcients from R =−0.56to −0.62weredetermined.Fig.5.Friction force,F F ,versus normal load,L N,in the scratch test3.1.4.Statistical e v aluation of acoustic emissionfor samples with di ﬀerent pre-sputtering time,t S.The Weibull statistical distribution function is applied for evaluating the fracture strength of hard and brittle Fig.6shows the correlations of friction work,W F,withceramics and was also proposed for the scratch test of pre-sputtering time,t S,for three ranges of ﬁlm thickness:hard coatings [16].The fracture tests of a series of 1.2–1.6m m,1.6–2.0m m,2.0–2.4m m.W Fdecreases withsamples yield a distribution of strength values that can increasing pre-sputtering time,t S.The ﬁlms werebe described by the Weibull distribution ing detached at higher loads,and the diamond scratched this distribution function,F (L ),it is possible to deter-the ﬁlm more than the substrate along the scratch trace mine the critical load,L C,for the fracture with a givenof 7mm.The correlation coe ﬃcients of R =−0.57and probability and the parameter m depending on the shape −0.88are signiﬁcant.of the distribution [17]:It is emphasized that signiﬁcant correlations could only be found for limited ranges of ﬁlm thickness.This F (L )=1−exp C −A L L CB mD.(2)proved to be true for all other test parameters of the present studies and conﬁrms the well-known ﬁnding that the results of adhesion tests can be compared only for The statistical evaluation was applied to the acoustic emission detected during the scratch.To study the typessimilar ﬁlmthicknesses.Fig.6.Friction work,W F ,versus pre-sputtering time,t S,for three ranges of ﬁlm thickness,d .R is the correlation coe ﬃcient.91H.Ollendorf,D.Schneider /Surface and Coatings Technology 113(1999)86–102Fig.7.Total number of acoustic emission signals,N AE ,during the scratch test versus pre-sputtering time,t S,for three classes of ﬁlm thickness,d .R is the correlation coe ﬃcient.of failure indicated by the signals,some tests were Weibull statistical distribution function in the form:stopped after the ﬁrst acoustic emission event.Microscopic investigations revealed that these acoustic ln ln {1/[1−F (L )]} =m ln L −m ln L C.(3)emission signals were always correlated with detach-ments of the ﬁlm.Therefore,the Weibull statistical F (L )was deduced from the normalized number of the scratch tests having shown an acoustic emission at the distribution was applied to the ﬁrst acoustic emission event detected in the scratch test.Twenty scratch tests load L .The critical load,L C,can be determined fromEq.(3)for ln ln{1/[1−F (L )]} =0,which is illustrated were performed for one distribution,ﬁve tests on each one of four samples of a test series.The results were in Fig.8.This is the load,L ,where 63.2%of all scratch tests released an acoustic emission signal.The parameter,plotted in a double-logarithmic diagram as shown in Fig.8for two sample series with a pre-sputtering time m ,can be deduced from the slope of ln ln{1/[1−F (L )]} versus ln(L )in Eq.(3).From the almost linear depen-of t S=2and 15min,respectively.This represents theFig.8.Double-logarithmic Weibull diagram for the probability,F ,of the ﬁrst acoustic emission event in the scratch test at the load,L N,for twosample series with di ﬀerent pre-sputtering times,t S .The deduction of the critical load,L C1,is shown.92H.Ollendorf,D.Schneider /Surface and Coatings Technology 113(1999)86–102Fig.9.Correlations of the critical load,L C1,with the pre-sputtering time,t S,for three classes of ﬁlm thickness d .R is the correlation coe ﬃcient.dence in Fig.8,it can be concluded that the ﬁrst signalssignals emit the ﬁrst signal at higher loads than samples showing only few signals.This could be explained by of the acoustic emission are Weibull-distributed.The correlations between critical load,L C1,with pre-lower residual stresses in the ﬁlms with more defects.A high defect density could prevent high residual stresses sputtering time,t S,are shown for the three classes ofﬁlm thicknesses in Fig.9.Correlation coe ﬃcients from occurring in the ﬁlm.Higher external loads must be applied to trigger the ﬁrst micro-fracture.However,by R =−0.5344to −0.762were determined.This suggests that the pre-sputtering time,t S,inﬂuences the acousticusing X-ray di ﬀraction,signiﬁcant di ﬀerences in residual stresses could not be detected by X-ray di ﬀraction.emission.However,it is emphasized that L C1decreaseswith increasing t S.This means that ﬁlms with a better-Further investigations were carried out to determine whether the Weibull distribution could also be applied than-expected adhesion show their ﬁrst brittle micro-fracture at lower loads.Obviously,L C1does not reﬂectto the acoustic emission of a single scratch test.This seems doubtful for tests with a high frequency of acoustic the e ﬀect of the pre-sputtering process in the expected manner.emission signals,since the fracture events cannot be assumed to be independent from each other,required Taking into account the activity of the acoustic emis-sion characterized by N AE(Fig.7)reveals the surprisingfor a statistical evaluation.However,the acoustic emis-sion usually starts with single isolated events whoseresult that samples showing many acoustic emissionFig.10.Double-logarithmic Weibull diagram of the acoustic emission in a single scratch test.93H.Ollendorf,D.Schneider /Surface and Coatings Technology 113(1999)86–1023.2.Four-point bending testThe four-point bending test is shown schematically in Fig.13.The sample was ﬁxed in the jig in such a way that the TiN ﬁlm was loaded by compressive stress to make the results comparable to those of the scratch test.The end of the sample was connected to an acoustic emission transducer to detect micro-fractures during the bending test.The samples were not coated within the area near the loading stamps so as to avoid the detection of acoustic signals other than those generated by the homogenous bending of the ﬁlm.Further details of the test procedure are described elsewhere [18,19].The data record of the bending test (Fig.14)shows the stress,s ,versus the strain,e ,in the upper layer of the sample and Fig.11.Double-logarithmic Weibull diagram of the acoustic emissionthe cumulative number of acoustic emission signals.in the ﬁrst stage of scratch test for three samples with di ﬀerent pre-Two test parameters were determined.The critical sputtering times,t S.strain,e C,was determined as the strain where 10%ofthe total number of the acoustic emission signals had origins can be assumed not to interact.Fig.10shows a been detected.The crack density,D C,was obtained fromWeibull diagram for the acoustic emission of a single an optical micrograph of the coated area after the scratch test.It can be seen that in the ﬁrst stage,the bending test.The stress–strain diagram did not yield acoustic emission events show a linear realtionship of any information about the ﬁlm since the e ﬀect of the the Weibull distribution in the double-logarithmic repre-2-m m-thick ﬁlm is too small compared to the 8-mm-sentation.This section of the diagram can be statistically thick steel substrate.analyzed,as shown in Fig.11.The e ﬀect of the pre-The micrographs in Fig.15a and b show the ﬁlms of sputtering time,t S,on the Weibull plot can be seen.two samples of di ﬀerent pre-sputtering time,t S.The ﬁlmIncreasing t Sshifts the distribution function to loweron the sample with a lower pre-sputtering time loads.A critical load,denoted L C2,was derived and(t S=2min,Fig.15b)shows more and longer cracks in plotted against t S in Fig.12.This shows that L C2dependsthe ﬁlm.The visible cracks are perpendicular to the on t S as well as L C1(Fig.9),and decreases with increas-surface.No detachments of the ﬁlms were observed.ing pre-sputtering time,t S.This suggests that bothThe crack density,D C,is plotted versus the sputteringparameters L C1and L C2reveal the same mechanicaltime,t S ,in Fig.16a.D Cis signiﬁcantly lower forproperty of the TiN ﬁlms.However,they both yield results contrary to the expected adhesion behavior.t S =15min than for t S=2min.This behavior is inFig.12.Correlations of the critical load,L C2,with the pre-sputtering time,t S,for three classes of ﬁlm thickness,d .R is the correlation coe ﬃcient.94H.Ollendorf,D.Schneider /Surface and Coatings Technology 113(1999)86–102Fig.13.Schematic representation of the four-point bending test.Fig.14.Data record of a four-point bending test of a TiN-coated sample with t S=2min,showing the cumulative number of acoustic emissionevents,C AE ,and the stress,s ,versus strain,e .The deduction of the critical strain,e C,is shown.agreement with that observed for the friction work,dimension,the blisters collapse,accompanied by the formation of a microscopic water jet that hits the surface W F ,and the acoustic emission activity,N AE,of the scratch test (Figs.6and 7).However,the critical strain,with a high pressure,generating a mechanical pulse.Since many blisters develop and collapse permanently,e C,shows an unexpected behavior.It indicates a thresh-old of the micro-fractures.Fig.16b reveals that eCthis test acts like many local impact tests on a large area and with a high repetition rate.Fig.18a–c show the decreases with increasing t S.One-tenth of all micro-fractures occurred at a lower strain in ﬁlms whose REM micrographs of three samples with di ﬀerent pre-sputtering times.In the cavitation test,the surface is adhesion was expected to be better.This corresponds to the results obtained for the critical loads L C1and LC2attacked in many parts,and destruction and detachment of the ﬁlm material can result.The ﬁlm with of the scratch test (Figs.9and 12).It seems that the acoustic emission signals detected in bending and scratch t S=15min shows the least damage (Fig.18a).The damage increases with decreasing t S.Image processingtests reveal the same fracture mechanism.was applied to determine the proportional area of the damage,A D .Fig.19shows A Dversus the pre-sputter3.3.Ca v itation testtime t S .The damaged area,A D,reduces with increasingpre-sputtering time,t S.This is an expected result.TheThe cavitation test is performed in a water tank in which the sample surface is exposed to high-power cavitation test yields the same evaluation behavior of the adhesion of the TiN ﬁlms as the friction work,W F,ultrasound (Fig.17)[20].An ultrasonic transducer with a diameter of 16mm is arranged about 0.5mm above and the acoustic emission activity,N AE,of the scratchtest and the crack density,D F,of the four-point bend-the sample.The high-power ultrasound generates blisters on the surface of the sample.Having reached a critical ing test.95H.Ollendorf,D.Schneider /Surface and Coatings Technology 113(1999)86–102Fig.17.Schematic representation of the cavitation test.3.4.Impact testThe impact test allows the local fatigue strength of the ﬁlm–substrate compound to be tested [21].A sche-matic representation of the test apparatus is shown in Fig.20.The sample is cyclically loaded by a ball of cemented carbide that is repetitively pushed on the sample surface.The cyclical loading is applied by a device that consists of a spring and a magnetic coil.The impact frequency can be varied from 0to 50Hz,and the force of the impact can be varied from 0to 1500N.The impact force is controlled by a strain gauge.The damage of the sample is evaluated by an optical micro-scope.The test parameter is the critical number of loading cycles,N C,up to the point at which the surfaceshows no further damage.The result has the form of a Woehler diagram (Fig.21a).N C versus t Sispresented(a)(b)Fig.15.Micrographs of TiN ﬁlms with di ﬀerent pre-sputtering time,in Fig.21b,which shows that the critical number of t S ,after the four-point bending test:(a)t S =15min;(b)t S=2min.cycles,N C,decreases with increasing pre-sputtering time,t S.The impact test indicated that pre-sputtering makes the ﬁlm adhesion worse.This corresponds to the results of the critical loads,L C1and L C2,of the scratch test(Figs.9and 12)and the critical strain,e C,of the four-point bending test (Fig.16b).3.5.Rockwell testThe advantage of this method is that it is easy to use,even in an industrial environment.A conventional hard-ness Rockwell test is performed and the damage pattern of the hard coating around the imprint is evaluated microscopically at a magniﬁcation of 100×.Standard damage pictures serve to classify the adhesion into six classes HF1–HF6[13,22].The Rockwell test was not su ﬃciently sensitive to distinguish between TiN ﬁlms with di ﬀerentpre-sputter-ing times.Even for test samples with a pre-sputtering Fig.16.Results of four-point bending test.(a)Crack density,D C,intime of only t S=1min,the test indicated that thethe ﬁlm after the test versus the sputtering time,t S.(b)Critical strain,e C ,versus sputtering time,t S.adhesion was of a good quality.。

汽车消声器的声学性能分析与结构优化

48机械设计与制造Machinery Design&Manufacture第4期2021年4月汽车消声器的声学性能分析与结构优化顾倩霞，左言言，赵海卫，宋文兵(江苏大学振动噪声研究所，江苏镇江212013)摘要：针对某三缸发动机排气嗓声超出目标限值，将声学性能作为评价指标，利用b声学有限元樸块对排气消声器的声学性能进行仿真分析，对比传递损失试验结果对该声学软件的仿真精度作出评价:b软件在整个频段与试验值较为接近，能准确的反映消声器的声学性能。

根据原排气消声器的传递损失分析结果,提出亥姆霍兹共振腔结构及阻抗复合型结构等参数设计的前后端消声器优化方案。

最终对优化后的排气消声器进行尾管嗓声试验，确认排气噪声达标。

关键词:排气消声器;仿真分析;传递损失;尾管噪声中图分类号:TH16;TB535.2文献标识码:A文章编号：1001-3997(2021 )04-0048-05Acoustic Performance Analysis and Optimized Design of Vehicle MufflerGU Qian-xia, ZUO Yan-yan, ZHAO Hai-wei, SONG Wen-bing(Institute of Noise and Vibration of Jiangsu University,Jiangsu Zhenjiang212013, China)Abstract：Base on a three-cylinder engine exhaust noise exceeding target limit y according to the evaluation index of acoustic performance y the analysis of acoustic performance was conducted in acoustic FEM module o f software VirtuaL Comparing the transmission loss test results to evaluate the simulation accuracy of the acoustic software：the simulation results〇/*b software were close to the experimental value on entire frequency band and accurately reflection on the acoustic performanceof the muffler.The simulalion results are compared with the test results to confirm the simulation accuracy.According to the analysis results of the transmission loss of the original exhaust muffler^optimization solutions for front and rear mufflers designed with parameters such as Helmholtz resonator and impedance compound structure was proposed for the frequencyband with poor muffling effect.Finally，the tail pipe noise test was performed on the optimized exhaust muffler to confirm thatthe exhaust noise reached the standard.Key Words：Exhaust Muffler；Simulation Analysis；Transmission Loss；Tailpipe Noisel引言2原排气消声器测试数据分析据国外有关资料统计，交通噪声占整个环境噪声比例达到75%,是目前影响城市环境和人体健康的主要噪声来源。

OS O.S. ENGINE 说明书

engine, to read the general 'SAFETY INSTRUCTIONS AND WARNINGS' in the following section and to strictly adhere to the advice contained therein.Also, please study the entire contents of this instruction manual, so as to familiarize yourself with The advice which follows is grouped under two headings according to the degree of damage or obvious sources of danger, but which, under certainhighly efficient internal-combustion machine whose power is capable of harming you, or others, if it is misused or abused. As owner, you, alone, are responsible for the safe operation of your engine, so act with discretion and care at all times. If at some future date, your O.S. engine is acquired by another person, we would respectfully request that theseinstructions are also passed on to its new owner.Model engine fuel is poisonous. Do not allow it to come into contact with the eyes or mouth. Always store it in a clearly marked container and out of the reach of children.Model engine fuel is also highly flammable. Keep it away from open flame, excessive heat, sources of sparks, or anything else which might ignite it. Do not smoke or allow anyone else to smoke, near to it.Model engines generate considerable heat. Do not touch any part of your engine until it has cooled. Contact with the muffler (silencer), cylinder head or exhaust header pipe, in particular, may result in a serious burn.Never operate your engine in an enclosed space. Model engines, like automobile engines, exhaust deadly carbon-monoxide. Run your engine only in an open area.exposure to a noisy exhaust (especially in the case of the more powerful highspeed engines) may eventually impair your hearing and such noise is also likely to cause annoyance to others over a wide area.The wearing of safety glasses is also strongly recommended.Take care that the glowplug clip or battery leads do not come into contact with rotating parts. Also check that the linkage to the throttle arm is secure.For their safety, keep all onlookers (especially small children) well back (at least 20 feet or 6 meters) when preparing your model for running.attempt to use it for any other purpose.Mount the engine in your model securely, following the manufacturers' recommendations, using appropriate screws and locknuts.To stop the engine, fully retard the throttle stick and trim lever on the trans-mitter, or, in an emergency, cut off the fuel supply by pinching the fuel delivery line from the tank.Warning! Immediately after a glowplug-ignition engine has been run and is still warm, conditions sometimes exist whereby it is just possible for the engine to abruptly restart if it is rotated over compression WITHOUT the glowplug battery being reconnected.Before starting the engine, always check the tightness of all the screws and nuts especially those of joint and movable parts such as throttle arm. Missing retightening the loose screws and nuts often causes the parts breakage that is capable of harming you.The Needle-Valve:Four adjustable controls are provided on this carburetor.For adjusting the mixture strength when the throttle is fully open.The Throttle Stop Screw:For setting the minimum idle speed:For adjusting the mixture strength at part-throttle and idle speed, to obtain steady idling and smooth acceleration to mid speed.The Metering Needle:NOTE: Readjustment may be necessary, occasionally to allow for changes in fuel formula, gear ratio or clutch engagement point.ENGINE INSTALLATIONSTARTING THE ENGINE & RUNNING-IN ('Breaking-in)Attention:It is vitally important to set the throttle at the correct position (i.e. with the driving wheels not in contact with the ground) it will rapidly over-heat and may be seriously damaged.The Mixture Control Valve:For changing the mixture strength at mid speed and acceleration. (Do not rotate the screw more than one turn.)21TM-R First, remove the original engine, from the engine mount.Install the engine on the engine mount with ground wire.Install the flywheel and clutch.T-MaxxRevo Install the electric starter taken from the original engine.Install the manifold supplied with the engine.Adjust the plastic ball end so that the throttle linkage may be connected correctly.T-MaxxRevoAdjust the stopper end so that the throttle linkage may be made correctly.Finally, connect the wire for glow plug heating to the glow plug.T-MaxxFinally, insert the wire for heating the glow plug.For long life and high performance, every engine needs to be 'run-in' or 'broken-in'. With care, running-in of the MAX-21TM can be carried out with the engine installed in the vehicle.Be sure to install the air-cleaner on the carburetor and use a muffler-pressurized fuel system.The somewhat violent changes of vehicle attitude that occur in off-road running, combined with the fact that, in buggy type cars, the fuel tank is often located some distance from the carburetor, means that fuel 'head' at the carburetor can vary and upset running.Therefore,it is recommended that a muffler pressurized fuel feed system be used.Never run your vehicle without installing the air cleaner. Dust and dirt that may otherwise be drawn into the engine will rapidly shorten its life.Fill the tank completely with fuel.Temporarily remove the glowplug to check that it glows bright red when energized.The carburetor on this engine has been set at the starting setting when the engine leaves the factory.Switch on the transmitter, and check that all the linkage moves correctly.When the engine starts, first allow it to operate in short runs on its very rich starting settings, with the glowplug battery still connected and with its driving wheels clear of the ground. The rich mixture will, under these conditions, provide adequate lubrication and cooling, indicated by profuse smoke from the exhaust.Next, disconnect the glowplug battery and try running the car on the track. If the engine stalls, open the throttle fractionally, but try to keep the engine running as rich as possible: if it stops because of being excessively over-rich, close the Needle-Valve 30˚ and try again.Run the car on the track until one tank of fuel has been consumed, then close the Needle-Valve 30˚. Repeat this procedure again until five tanks of fuel have been consumed, during which time the throttle may be opened for brief bursts of increased power. If the engine stops at medium speeds, close the Mixture Control Valve 30˚.30˚Needle30˚30˚The position of the needle-valve when starting the Close the needle-valve approx. 30˚ after running the vehicle for every one full tanks of fuel. Repeat this procedure around five times.Note:If the engine should need to be disassembled (e.g. for cleaning or minor parts replacement), it is advisable to return the needle-valve to the original rich, starting setting and check whether further running-in time is required before the car is raced again. In the event of any major working parts (e.g. piston/cylinder liner assembly) being replaced or the fuel being changed, especially to high nitro fuel, the complete running-in should be repeated.Warning!Do not touch rotating parts, engine and silencer when stopping the engine as they become very hot, and contact with them may result in a serious burn.on the transmitter.carburetor.FINAL ADJUSTMENTFinal adjustment should be carried out only after the running-in has been completed.Run the vehicle (with throttle fully open) over the longest available straight course, in order to observe the model's speed. Next return the car to the starting point, close the Needle-Valve 30˚ and repeat the run, taking note of the improvement in performance.Continue with further runs, gradually reducing the Needle-Valve setting and aiming to achieve the highest straight-line speed. Remember, however, that, if the Needle-Valve is shut down too far, the engine will overheat and, accompanied by visibly diminished exhaust smoke, the model will lose speed. At this point, throttle down immediately, stop the vehicle and reopen the Needle-Valve 30˚.With the engine running, close the throttle and allow it to idle for about five seconds, then reopen the throttle fully. If, at this point, the engine puffs out an excessive amount of smoke and the vehicle does not accelerate smoothly and rapidly, it is probable that the idle mixture is too rich. In this case, turn the Metering Needle clockwise 30˚. If, on the other hand, the engine tends to speed up momentarily and then cut out abruptly when the throttle is opened, the idle mixture is too lean. Correct this by turning the Metering Needle counter-clockwise 30˚.NOTE:Metering Needle adjustment should be made in steps of not more than 30˚, carefully checking the effect,on throttle response, of each small adjustment.Carry out adjustments patiently, under actual running conditions, until the engine responds quickly and positively to the throttle control.Warning!Mixture adjustments (whether via the Metering Needle, or the Needle-Valve) cannot be made accurately under 'no-load' conditions, which, in any case, are not advised, since such operation carries the risk of seriously damaging the engine through over-revving and overheating.With the optimum mixture control position, light smoke is visible during high speed running,and the engine rpm increases smoothly during acceleration.Remember that, if the engine is operated with the fuel/air mixture slightly too lean, it will overheat and run unevenly.As with all engines, it is advisable to set both the needle-valve and metering needle slightly on the rich side of the best rpm setting, as a safety measure.If the engine runs too fast with the throttle closed, the throttle stop screw should be turned counter-clockwise to allow the throttle opening to be reduced.Finally, beyond the nominal break-in period, a slight readjustment toward a leaner needle setting may be required to maintain maximum performance.CARE AND MAINTENANCE2.3.any fuel may, by accumulating and partially obstructing fuel flow, cause engine performance to become erratic and unreliable.O.S. 'Super-Filters' (large and small) are available, as optional extras, to deal with this problem.One of these filters installed to the pickup tube inside your refueling container, will prevent the entry of foreign material into the fuel tank. It is also recommended that a good in-line filter be installed between the tank and carburetor.Do not forget to clean the filters regularly to remove dirt and lint that accumulate on the filter screens. Also, clean the carburetor itself occasionally.At the end of each operating session, drain out any fuel that may remain in the fuel tank. Afterwards,energize the glow-plug and try to restart the engine, to burn off any fuel that may remain inside the engine. Repeat this procedure until the engine fails to fire. Do this while the engine is still warm. 4.Then, inject some after-run oil into the engine, and rotate the engine with an electric starter for 4 to 5 seconds to distribute the oil to all the working parts.Note:5.Finally, when cleaning the exterior of the engine, use methanol or a household cleaning agent.Do not use gasoline, kerosene, or any petroleum based chemical which can damage silicone fuel tubing.CHECKING THE ENGINElong time running due to wearing of parts. It is suggested to replace necessary parts when the following symptoms are detected.Engine sound changes and easily overheats.Power has dropped extremely.Idle is unstable and/or engine tends to stop at idle.In most cases, ball bearings, cylinder & piston assembly, connecting rod and/or crankcase have become worn. Check the parts carefully and replace them if necessary.O.S. GENUINE PARTS & ACCESSORIES 71410150714102007141025071410300714112007141125071412300714135507141360071413700O.S. SPEED HEX WRENCH DRIVER 1.5O.S. SPEED HEX WRENCH DRIVER 2.0O.S. SPEED HEX WRENCH DRIVER 2.5O.S. SPEED HEX WRENCH DRIVER 3.0O.S. SPEED HEX BALL WRENCH DRIVER 2.0O.S. SPEED HEX BALL WRENCH DRIVER 2.5O.S. SPEED FLAT HEAD SCREWDRIVER 3.0O.S. SPEED NUT DRIVER 5.5O.S. SPEED NUT DRIVER 6.0O.S. SPEED NUT DRIVER 7.0O.S. SPEED DRIVER TOOLSCode No.Description71414015714140207141402571414030714141207141412571414230714143557141436071414370O.S. SPEED HEX WRENCH TIP ONLY 1.5O.S. SPEED HEX WRENCH TIP ONLY 2.0O.S. SPEED HEX WRENCH TIP ONLY 2.5O.S. SPEED HEX WRENCH TIP ONLY 3.0O.S. SPEED HEX BALL WRENCH TIP ONLY 2.0O.S. SPEED HEX BALL WRENCH TIP ONLY 2.5O.S. SPEED FLAT HEAD SCREWDRIVER TIP 3.0O.S. SPEED NUT DRIVER TIP ONLY 5.5O.S. SPEED NUT DRIVER TIP ONLY 6.0O.S. SPEED NUT DRIVER TIP ONLY 7.0Code No.DescriptionThe specifications are subject to alteration for improvement without notice.O.S. GLOW PLUG(71520100)(71415100)(71415200)(71415300)O.S. SPEED CLUTCH WRENCH & ADJUSTER O.S. SPEED FLYWHEEL KEY O.S. SPEED FLYWHEEL PULLER O.S. SPEED PLUG WRENCH http://www.os-engines.co.jp6-15 3-Chome Imagawa Higashisumiyoshi-ku Osaka 546-0003, Japan TEL. (06)6702-0225FAX. (06)6704-2722Dimensions (mm)THREE VIEW DRAWINGDo not inject after-run oil into the carburetor as this can cause the O rings inside the carburetor to deteriorate.Add the oil through the glowplug hole and turn the engine over several times by hand.(72106172)(71653000) (22884254)(72506100)MANIFOLD SPRING (2pcs.)2.5mm x 1000mmO.S. SPEED CILICONE TUBE O.S. SPEED DUST CAP SET FOR 12-30 CLASS 3mm(2pcs.) / 16mm(2pcs.) / 18mm(1pc.)(71417100)No.1(71417200)No.2(71415500)(71415400)O.S. SPEED BODY REAMERO.S. SPEED SPRING REMOVER O.S. SPEED PHILLIPS SCREW DRIVER O.S. SPEED PHILLIPS SCREW DRIVER The correct functioning of the carburetor depends on its small fuel orifices remaining clear.REALIGNMENT OF METERING NEEDLE AND MIXTURE CONTROL VALVEIn the course of making carburetor adjustments, it is just possible that the Metering Needle and the Mixture Control Valve may be inadvertently screwed in or out too far and thereby moved beyond its effective adjustment range.The basic positions can be found by rotating the Metering Needle until its slotted head is flush with theball link body or throttle lever body.When storing the engine, install the cap on the exhaust port, carburetor, etc. to prevent dust from entering the engine.Caution:The rear crankshaft bearing of this engine uses a special plastic retainer. If the front housing needs to be heated to remove or replace the bearing, do not allow the bearing to exceed 120˚C (248˚F), otherwise it may be damaged and rendered unserviceable.(Optional extra)INSTALLING DUST CAPS Type of screwC…Cap Screw M…Oval Fillister-Head Screw21TM (T-Maxx) ENGINE EXPLODED VIEW & ENGINE PARTS LIST1231712321TM (Revo) ENGINE EXPLODED VIEW & ENGINE PARTS LISTType of screwC…Cap Screw M…Oval Fillister-Head Screw11K / 11K-R CARBURETOR EXPLODED VIEW &ENGINE PARTS LIST(21TM-T & 21TM-R)60091890 122002。

数学专业词汇及翻译

一、字母顺序表 (1)二、常用的数学英语表述 (7)三、代数英语（高端） (13)一、字母顺序表1、数学专业词汇Aabsolute value 绝对值 accept 接受 acceptable region 接受域additivity 可加性 adjusted 调整的 alternative hypothesis 对立假设analysis 分析 analysis of covariance 协方差分析 analysis of variance 方差分析 arithmetic mean 算术平均值 association 相关性 assumption 假设 assumption checking 假设检验availability 有效度average 均值Bbalanced 平衡的 band 带宽 bar chart 条形图beta-distribution 贝塔分布 between groups 组间的 bias 偏倚 binomial distribution 二项分布 binomial test 二项检验Ccalculate 计算 case 个案 category 类别 center of gravity 重心 central tendency 中心趋势 chi-square distribution 卡方分布 chi-square test 卡方检验 classify 分类cluster analysis 聚类分析 coefficient 系数 coefficient of correlation 相关系数collinearity 共线性 column 列 compare 比较 comparison 对照 components 构成，分量compound 复合的 confidence interval 置信区间 consistency 一致性 constant 常数continuous variable 连续变量 control charts 控制图 correlation 相关 covariance 协方差 covariance matrix 协方差矩阵 critical point 临界点critical value 临界值crosstab 列联表cubic 三次的，立方的 cubic term 三次项 cumulative distribution function 累加分布函数 curve estimation 曲线估计Ddata 数据default 默认的definition 定义deleted residual 剔除残差density function 密度函数dependent variable 因变量description 描述design of experiment 试验设计 deviations 差异 df.(degree of freedom) 自由度 diagnostic 诊断dimension 维discrete variable 离散变量discriminant function 判别函数discriminatory analysis 判别分析distance 距离distribution 分布D-optimal design D-优化设计Eeaqual 相等 effects of interaction 交互效应 efficiency 有效性eigenvalue 特征值equal size 等含量equation 方程error 误差estimate 估计estimation of parameters 参数估计estimations 估计量evaluate 衡量exact value 精确值expectation 期望expected value 期望值exponential 指数的exponential distributon 指数分布 extreme value 极值F factor 因素，因子 factor analysis 因子分析 factor score 因子得分 factorial designs 析因设计factorial experiment 析因试验fit 拟合fitted line 拟合线fitted value 拟合值 fixed model 固定模型 fixed variable 固定变量 fractional factorial design 部分析因设计 frequency 频数 F-test F检验 full factorial design 完全析因设计function 函数Ggamma distribution 伽玛分布 geometric mean 几何均值 group 组Hharmomic mean 调和均值 heterogeneity 不齐性histogram 直方图 homogeneity 齐性homogeneity of variance 方差齐性 hypothesis 假设 hypothesis test 假设检验Iindependence 独立 independent variable 自变量independent-samples 独立样本 index 指数 index of correlation 相关指数 interaction 交互作用 interclass correlation 组内相关 interval estimate 区间估计 intraclass correlation 组间相关 inverse 倒数的iterate 迭代Kkernal 核 Kolmogorov-Smirnov test柯尔莫哥洛夫-斯米诺夫检验 kurtosis 峰度Llarge sample problem 大样本问题 layer 层least-significant difference 最小显著差数 least-square estimation 最小二乘估计 least-square method 最小二乘法 level 水平 level of significance 显著性水平 leverage value 中心化杠杆值 life 寿命 life test 寿命试验 likelihood function 似然函数 likelihood ratio test 似然比检验linear 线性的 linear estimator 线性估计linear model 线性模型 linear regression 线性回归linear relation 线性关系linear term 线性项logarithmic 对数的logarithms 对数 logistic 逻辑的 lost function 损失函数Mmain effect 主效应 matrix 矩阵 maximum 最大值 maximum likelihood estimation 极大似然估计 mean squared deviation(MSD) 均方差 mean sum of square 均方和 measure 衡量 media 中位数 M-estimator M估计minimum 最小值 missing values 缺失值 mixed model 混合模型 mode 众数model 模型Monte Carle method 蒙特卡罗法 moving average 移动平均值multicollinearity 多元共线性multiple comparison 多重比较 multiple correlation 多重相关multiple correlation coefficient 复相关系数multiple correlation coefficient 多元相关系数 multiple regression analysis 多元回归分析multiple regression equation 多元回归方程 multiple response 多响应 multivariate analysis 多元分析Nnegative relationship 负相关 nonadditively 不可加性 nonlinear 非线性 nonlinear regression 非线性回归 noparametric tests 非参数检验 normal distribution 正态分布null hypothesis 零假设 number of cases 个案数Oone-sample 单样本 one-tailed test 单侧检验 one-way ANOVA 单向方差分析 one-way classification 单向分类 optimal 优化的optimum allocation 最优配制 order 排序order statistics 次序统计量 origin 原点orthogonal 正交的 outliers 异常值Ppaired observations 成对观测数据paired-sample 成对样本parameter 参数parameter estimation 参数估计 partial correlation 偏相关partial correlation coefficient 偏相关系数 partial regression coefficient 偏回归系数 percent 百分数percentiles 百分位数 pie chart 饼图 point estimate 点估计 poisson distribution 泊松分布polynomial curve 多项式曲线polynomial regression 多项式回归polynomials 多项式positive relationship 正相关 power 幂P-P plot P-P概率图predict 预测predicted value 预测值prediction intervals 预测区间principal component analysis 主成分分析 proability 概率 probability density function 概率密度函数 probit analysis 概率分析 proportion 比例Qqadratic 二次的 Q-Q plot Q-Q概率图 quadratic term 二次项 quality control 质量控制 quantitative 数量的，度量的 quartiles 四分位数Rrandom 随机的 random number 随机数 random number 随机数 random sampling 随机取样random seed 随机数种子 random variable 随机变量 randomization 随机化 range 极差rank 秩 rank correlation 秩相关 rank statistic 秩统计量 regression analysis 回归分析regression coefficient 回归系数regression line 回归线reject 拒绝rejection region 拒绝域 relationship 关系 reliability 可*性 repeated 重复的report 报告，报表 residual 残差 residual sum of squares 剩余平方和 response 响应risk function 风险函数 robustness 稳健性 root mean square 标准差 row 行 run 游程run test 游程检验Sample 样本 sample size 样本容量 sample space 样本空间 sampling 取样 sampling inspection 抽样检验 scatter chart 散点图 S-curve S形曲线 separately 单独地 sets 集合sign test 符号检验significance 显著性significance level 显著性水平significance testing 显著性检验 significant 显著的，有效的 significant digits 有效数字 skewed distribution 偏态分布 skewness 偏度 small sample problem 小样本问题 smooth 平滑 sort 排序 soruces of variation 方差来源 space 空间 spread 扩展square 平方 standard deviation 标准离差 standard error of mean 均值的标准误差standardization 标准化 standardize 标准化 statistic 统计量 statistical quality control 统计质量控制 std. residual 标准残差 stepwise regression analysis 逐步回归 stimulus 刺激 strong assumption 强假设 stud. deleted residual 学生化剔除残差stud. residual 学生化残差 subsamples 次级样本 sufficient statistic 充分统计量sum 和 sum of squares 平方和 summary 概括，综述Ttable 表t-distribution t分布test 检验test criterion 检验判据test for linearity 线性检验 test of goodness of fit 拟合优度检验 test of homogeneity 齐性检验 test of independence 独立性检验 test rules 检验法则 test statistics 检验统计量 testing function 检验函数 time series 时间序列 tolerance limits 容许限total 总共，和 transformation 转换 treatment 处理 trimmed mean 截尾均值 true value 真值 t-test t检验 two-tailed test 双侧检验Uunbalanced 不平衡的 unbiased estimation 无偏估计 unbiasedness 无偏性 uniform distribution 均匀分布Vvalue of estimator 估计值 variable 变量 variance 方差 variance components 方差分量 variance ratio 方差比 various 不同的 vector 向量Wweight 加权，权重 weighted average 加权平均值 within groups 组内的ZZ score Z分数2. 最优化方法词汇英汉对照表Aactive constraint 活动约束 active set method 活动集法 analytic gradient 解析梯度approximate 近似 arbitrary 强制性的 argument 变量 attainment factor 达到因子Bbandwidth 带宽 be equivalent to 等价于 best-fit 最佳拟合 bound 边界Ccoefficient 系数 complex-value 复数值 component 分量 constant 常数 constrained 有约束的constraint 约束constraint function 约束函数continuous 连续的converge 收敛 cubic polynomial interpolation method三次多项式插值法 curve-fitting 曲线拟合Ddata-fitting 数据拟合 default 默认的，默认的 define 定义 diagonal 对角的 direct search method 直接搜索法 direction of search 搜索方向 discontinuous 不连续Eeigenvalue 特征值 empty matrix 空矩阵 equality 等式 exceeded 溢出的Ffeasible 可行的 feasible solution 可行解 finite-difference 有限差分 first-order 一阶GGauss-Newton method 高斯-牛顿法 goal attainment problem 目标达到问题 gradient 梯度 gradient method 梯度法Hhandle 句柄 Hessian matrix 海色矩阵Independent variables 独立变量inequality 不等式infeasibility 不可行性infeasible 不可行的initial feasible solution 初始可行解initialize 初始化inverse 逆 invoke 激活 iteration 迭代 iteration 迭代JJacobian 雅可比矩阵LLagrange multiplier 拉格朗日乘子 large-scale 大型的 least square 最小二乘 least squares sense 最小二乘意义上的 Levenberg-Marquardt method 列文伯格-马夸尔特法line search 一维搜索 linear 线性的 linear equality constraints 线性等式约束linear programming problem 线性规划问题 local solution 局部解M medium-scale 中型的 minimize 最小化 mixed quadratic and cubic polynomialinterpolation and extrapolation method 混合二次、三次多项式内插、外插法multiobjective 多目标的Nnonlinear 非线性的 norm 范数Oobjective function 目标函数 observed data 测量数据 optimization routine 优化过程optimize 优化 optimizer 求解器 over-determined system 超定系统Pparameter 参数 partial derivatives 偏导数 polynomial interpolation method 多项式插值法Qquadratic 二次的 quadratic interpolation method 二次内插法 quadratic programming 二次规划Rreal-value 实数值 residuals 残差 robust 稳健的 robustness 稳健性，鲁棒性S scalar 标量 semi-infinitely problem 半无限问题 Sequential Quadratic Programming method 序列二次规划法 simplex search method 单纯形法 solution 解 sparse matrix 稀疏矩阵 sparsity pattern 稀疏模式 sparsity structure 稀疏结构 starting point 初始点 step length 步长 subspace trust region method 子空间置信域法 sum-of-squares 平方和 symmetric matrix 对称矩阵Ttermination message 终止信息 termination tolerance 终止容限 the exit condition 退出条件 the method of steepest descent 最速下降法 transpose 转置Uunconstrained 无约束的 under-determined system 负定系统Vvariable 变量 vector 矢量Wweighting matrix 加权矩阵3 样条词汇英汉对照表Aapproximation 逼近 array 数组 a spline in b-form/b-spline b样条 a spline of polynomial piece /ppform spline 分段多项式样条Bbivariate spline function 二元样条函数 break/breaks 断点Ccoefficient/coefficients 系数cubic interpolation 三次插值/三次内插cubic polynomial 三次多项式 cubic smoothing spline 三次平滑样条 cubic spline 三次样条cubic spline interpolation 三次样条插值/三次样条内插 curve 曲线Ddegree of freedom 自由度 dimension 维数Eend conditions 约束条件 input argument 输入参数 interpolation 插值/内插 interval取值区间Kknot/knots 节点Lleast-squares approximation 最小二乘拟合Mmultiplicity 重次 multivariate function 多元函数Ooptional argument 可选参数 order 阶次 output argument 输出参数P point/points 数据点Rrational spline 有理样条 rounding error 舍入误差（相对误差）Sscalar 标量 sequence 数列（数组） spline 样条 spline approximation 样条逼近/样条拟合spline function 样条函数 spline curve 样条曲线 spline interpolation 样条插值/样条内插 spline surface 样条曲面 smoothing spline 平滑样条Ttolerance 允许精度Uunivariate function 一元函数Vvector 向量Wweight/weights 权重4 偏微分方程数值解词汇英汉对照表Aabsolute error 绝对误差 absolute tolerance 绝对容限 adaptive mesh 适应性网格Bboundary condition 边界条件Ccontour plot 等值线图 converge 收敛 coordinate 坐标系Ddecomposed 分解的 decomposed geometry matrix 分解几何矩阵 diagonal matrix 对角矩阵 Dirichlet boundary conditions Dirichlet边界条件Eeigenvalue 特征值 elliptic 椭圆形的 error estimate 误差估计 exact solution 精确解Ggeneralized Neumann boundary condition 推广的Neumann边界条件 geometry 几何形状geometry description matrix 几何描述矩阵 geometry matrix 几何矩阵 graphical user interface（GUI）图形用户界面Hhyperbolic 双曲线的Iinitial mesh 初始网格Jjiggle 微调LLagrange multipliers 拉格朗日乘子Laplace equation 拉普拉斯方程linear interpolation 线性插值 loop 循环Mmachine precision 机器精度 mixed boundary condition 混合边界条件NNeuman boundary condition Neuman边界条件 node point 节点 nonlinear solver 非线性求解器 normal vector 法向量PParabolic 抛物线型的 partial differential equation 偏微分方程 plane strain 平面应变 plane stress 平面应力 Poisson's equation 泊松方程 polygon 多边形 positive definite 正定Qquality 质量Rrefined triangular mesh 加密的三角形网格 relative tolerance 相对容限 relative tolerance 相对容限 residual 残差 residual norm 残差范数Ssingular 奇异的二、常用的数学英语表述1.Logic∃there exist∀for allp⇒q p implies q / if p, then qp⇔q p if and only if q /p is equivalent to q / p and q are equivalent2.Setsx∈A x belongs to A / x is an element (or a member) of Ax∉A x does not belong to A / x is not an element (or a member) of AA⊂B A is contained in B / A is a subset of BA⊃B A contains B / B is a subset of AA∩B A cap B / A meet B / A intersection BA∪B A cup B / A join B / A union BA\B A minus B / the diference between A and BA×B A cross B / the cartesian product of A and B3. Real numbersx+1 x plus onex-1 x minus onex±1 x plus or minus onexy xy / x multiplied by y(x - y)(x + y) x minus y, x plus yx y x over y= the equals signx = 5 x equals 5 / x is equal to 5x≠5x (is) not equal to 5x≡y x is equivalent to (or identical with) yx ≡ y x is not equivalent to (or identical with) yx > y x is greater than yx≥y x is greater than or equal to yx < y x is less than yx≤y x is less than or equal to y0 < x < 1 zero is less than x is less than 10≤x≤1zero is less than or equal to x is less than or equal to 1| x | mod x / modulus xx 2 x squared / x (raised) to the power 2x 3 x cubedx 4 x to the fourth / x to the power fourx n x to the nth / x to the power nx −n x to the (power) minus nx (square) root x / the square root of xx 3 cube root (of) xx 4 fourth root (of) xx n nth root (of) x( x+y ) 2 x plus y all squared( x y ) 2 x over y all squaredn! n factorialx ^ x hatx ¯ x barx ˜x tildex i xi / x subscript i / x suffix i / x sub i∑ i=1 n a i the sum from i equals one to n a i / the sum as i runs from 1 to n of the a i4. Linear algebra‖ x ‖the norm (or modulus) of xOA →OA / vector OAOA ¯ OA / the length of the segment OAA T A transpose / the transpose of AA −1 A inverse / the inverse of A5. Functionsf( x ) fx / f of x / the function f of xf:S→T a function f from S to Tx→y x maps to y / x is sent (or mapped) to yf'( x ) f prime x / f dash x / the (first) derivative of f with respect to xf''( x ) f double-prime x / f double-dash x / the second derivative of f with r espect to xf'''( x ) triple-prime x / f triple-dash x / the third derivative of f with respect to xf (4) ( x ) f four x / the fourth derivative of f with respect to x∂f ∂ x 1the partial (derivative) of f with respect to x1∂ 2 f ∂ x 1 2the second partial (derivative) of f with respect to x1∫ 0 ∞the integral from zero to infinitylim⁡x→0 the limit as x approaches zerolim⁡x→0 + the limit as x approaches zero from abovelim⁡x→0 −the limit as x approaches zero from belowlog e y log y to the base e / log to the base e of y / natural log (of) yln⁡y log y to the base e / log to the base e of y / natural log (of) y一般词汇数学mathematics, maths(BrE), math(AmE)公理axiom定理theorem计算calculation运算operation证明prove假设hypothesis, hypotheses(pl.)命题proposition算术arithmetic加plus(prep.), add(v.), addition(n.)被加数augend, summand加数addend和sum减minus(prep.), subtract(v.), subtraction(n.)被减数minuend减数subtrahend差remainder乘times(prep.), multiply(v.), multiplication(n.)被乘数multiplicand, faciend乘数multiplicator积product除divided by(prep.), divide(v.), division(n.)被除数dividend除数divisor商quotient等于equals, is equal to, is equivalent to 大于is greater than小于is lesser than大于等于is equal or greater than小于等于is equal or lesser than运算符operator数字digit数number自然数natural number整数integer小数decimal小数点decimal point分数fraction分子numerator分母denominator比ratio正positive负negative零null, zero, nought, nil十进制decimal system二进制binary system十六进制hexadecimal system权weight, significance进位carry截尾truncation四舍五入round下舍入round down上舍入round up有效数字significant digit无效数字insignificant digit代数algebra公式formula, formulae(pl.)单项式monomial多项式polynomial, multinomial系数coefficient未知数unknown, x-factor, y-factor, z-factor 等式，方程式equation一次方程simple equation二次方程quadratic equation三次方程cubic equation四次方程quartic equation不等式inequation阶乘factorial对数logarithm指数，幂exponent乘方power二次方，平方square三次方，立方cube四次方the power of four, the fourth power n次方the power of n, the nth power开方evolution, extraction二次方根，平方根square root三次方根，立方根cube root四次方根the root of four, the fourth root n次方根the root of n, the nth root集合aggregate元素element空集void子集subset交集intersection并集union补集complement映射mapping函数function定义域domain, field of definition值域range常量constant变量variable单调性monotonicity奇偶性parity周期性periodicity图象image数列，级数series微积分calculus微分differential导数derivative极限limit无穷大infinite(a.) infinity(n.)无穷小infinitesimal积分integral定积分definite integral不定积分indefinite integral有理数rational number无理数irrational number实数real number虚数imaginary number复数complex number矩阵matrix行列式determinant几何geometry点point线line面plane体solid线段segment射线radial平行parallel相交intersect角angle角度degree弧度radian锐角acute angle直角right angle钝角obtuse angle平角straight angle周角perigon底base边side高height三角形triangle锐角三角形acute triangle直角三角形right triangle直角边leg斜边hypotenuse勾股定理Pythagorean theorem钝角三角形obtuse triangle不等边三角形scalene triangle等腰三角形isosceles triangle等边三角形equilateral triangle四边形quadrilateral平行四边形parallelogram矩形rectangle长length宽width附：在一个分数里，分子或分母或两者均含有分数。

Volvo RET-TH 刹车器说明书

RET-TH is a compact, gearbox-mounted, hydraulic retarder that effectively supplements the vehicle’s ord inary brake system. It is suited to a number of manual gearboxes as well as to I-Shift.The retarder is coordinated with the engine’s exhaust brake, which results in high overall braking power. Volvo’s most power-ful engine brakes can be used, and a special function ensures that the rear axle is not overloaded.Using the additional brake as primary brake limits wear on the truck’s ordinary brakes, which reduces total operating costs. The compact retarder is very suitable for regional and long-haul transports in hilly areas. Retaining a safe driving, the aver-age speed can be increased as the retarder makes it possible to maintain higher speeds when driving on long downgrades. This results in a considerable increase in vehicle productivity. The retarder is fitted with a cruise control function that makes it easier for the driver to maintain a constant speed when driving downhill. Since the retarder is connected to the propeller shaft, braking power is also utilised when changing gears. Engaging and regulating the retarder is carried out conveniently with a lever next to the steering wheel.The retarder should be regarded as an integrated part of the brake system, and it must be factory mounted as it cannot be retrofitted Test 8″.FEATURES AND BENEFITSDesignation ...................................................................................RET-TH Manufacturer .....................................................................................Voith Max. brake torque on propeller shaft ......................................3250 Nm Max. brake torque at 750 r/min .............................................3000 Nm Max. brake torque at 500 r/min ..............................................1800 Nm Installation weight including oil ....................................................105 kg Oil change volume .............................................................................5.4 l SPECIFICATION• Compact and durable design with few moving parts re-sults in a long service life and high vehicle productivity.• Coordinated with the engine’s exhaust brake.• High braking torque that increases driving safety and reduces wear on the vehicle’s ordinary brake system.• Easy-to-access manual control provides exactly the right amount of braking power in every situation.• Cruise control function provides automatic cruise control on downgrades.•Approved for ADR transport.* In the case of continuous operation, effect is reduced when water and oil temperature increase. ** Also for EBR-EPGC.Simple design provides high vehicle reliabilityThe RET-TH is a compact, closed unit with few moving parts, which results in minimal wear and high vehicle reliability.The retarder consists primarily of two impellers; a fixed one (stator) and a rotating one (rotor) which counteract each other with the help of oil. Due to the fact that the blades on the stator and rotor are angled towards each other, the flow of oil between them is counteracted.When the rotor (1), which is fitted to the gearboxes’ output shaft, rotates, oil (2) is forced toward the stator (3), which is fixed in the retarder housing.When oil reaches the stator’s blades, a braking effect is cre-ated against the movement of the rotor, which means that the rotation of the propeller shaft is braked.The retarder’s control module regulates the oil volume and the oil pressure in the retarder. The amount of brake force is dependent on the pressure and the amount of oil pressed in between the rotor and the stator.FACT SHEETRetarder RET-THMultifunction control stalkThe control stalk for auxiliary brakes has three or five positions,depending on the type of gearbox that the truck is equipped with.A Automatic mode.Brake Blending is active if Cruise Control is inactive. When the brake pedal is depressed, the braking force is blended between the ordinary brakes and the auxiliary brakes.O All auxiliary brakes are off.1-3 Brake level settings.Provides settings between 20 and 100%. The total brake torque depends on which auxiliary brakes that arefitted on the vehicle, load condition and retarder temperature. The auxiliary brake is activated when the accelerator pedal is released.On control stalk with setting 1 only gives full braking effect from the Exhaust Pressure Governor.B Brake program mode.On vehicles with I-Shift or Powertronic, there is also a “B-button” that is used to activate the “brake program”. This functionprovides faster down-changes during braking.Trailer brake symbol. When the truck is equipped with trailer brake this function is also controlled with the auxiliary brake control stalk.Auxiliary brake symbol.Reduced operating costs increase profitabilityThanks to the retarder’s high braking torque, it can handle the majority of all braking situations. This results in reduced wear on the ordinary brakes, which means lower maintenance and repair costs.The retarder is coordinated with the engine’s exhaust brake, which provides high total braking power. A special function also ensures that the rear axle is not overloaded at high simultane-ous braking torque. The retarder installation is integrated in the transmission.The retarder weighs approximately 105 kg and the gearboxes’ total length is increased by only approximately 100 mm. Gear-boxdriven power take-offs can be used with no limitations.The compact retarder normally does not require any serviceor maintenance in addition to one oil change per year.。

除雪铲分段式避障结构设计与铲刃分析

.树械研究与应用.2020年第6期（第33卷，总第170期)研究与试验doi ： 10.16576/ki. 1007-4414.2020.06.007除雪铲分段式避障结构设计与铲刃分析屈文涛、吕瞾、王泽威\薛亚刚2,李志栋3(丨.西安石油大学机械工程学院，陕西西安710065; 2.陕西汽车控股集团有限公司，陕西西安710200;3.陕西重型汽车有限公司，陕西西安710200)摘要：为有效地避免清洗/除雪一体化车在遇到小型障碍物时出现的遗雪量增多的问题，提高除雪效率，设计了一种除雪铲分段式避障模块结构,.，利用Pro/E完成除雪铲铲刃的参数化建模，并结合A N SY S有限元分析除雪铲工作时除雪铲铲刃的应力应变情况，仿真结果显示其最大应力为3.82x l〇5P a,在其许用应力范围内，验证了该清洗/除雪一体化车除雪铲避障结构设计的合理性，为除雪铲避障结构的设计提供理论参考关键词：分段式避障模块；结构设计；除雪铲铲刃；有限元分析中图分类号：U4I8 文献标志码:A文章编号：1007-44丨4(2020)06-002丨-03Design for Segmented Obstacle Avoidance Structure of Snow Shovel and Analysis on the Shovel Blade QU W en-tao', LV Zhao1, WANG Ze-wei' , XUE Ya-gang2, LI Zhi-dong3(1. School of Mechanical Engineering y Xi'an Shiyou University y Xi'an Shaanxi 710065, China；2.Shaanxi Automobile Holding Group Co., Ltdy Xi'an Shaanxi 710200，China;3.Shaanxi Heavy Duty Truck Co., Ltd, Xi'an Shaanxi 710200, China)A bstract：In order to effectively avoid the problem of amount increasing of snow left in the cleaning /snow removal integratedvehicles when they encounter small obstacles and to improve the snow removal efficiency, a type of segmented obstacle avoidance module structure for the snow removal shovel is designed in this paper. The parametric modeling of the snowplow blade is completed by using P ro/E；the stress and strain of the snowplow blade during working process are analyzed with ANSYS finite element method. The simulation results show that the maximum stress is 3.82? 105 Pa, within the allowable stress range of snow removal shovel ；thus the rationality of the design for the obstacle avoidance structure of snow removal shovel in the clean-ing/snow removal integrated vehicle is verified. It would provide a theoretical reference for the design of snow removal shovel obstacle avoidance structure.Key words：segmented obstacle avoidance module；structural design；snow removal blade；finite element analysis0引言我国的北方许多地区，每年都存在较长的降雪期，积雪与结冰现象容易诱发交通事故，影响正常交通[1]。

迈尼霍尔小型压力调节器ARJ1020F说明书

O u t l e t p r e s s u r e (M P a )O u t l e t p r e s s u r e (M P a )Flow rate (l /min (ANR))Inlet pressure (MPa)Initial set pointMiniature RegulatorSeries ARJ1020FModelFluidOUT side (Applicable tubing O.D.)IN sidePort size Ambient and fluid temperature Construction Weight (kg)Cracking pressure (Valve)Applicable tubing materialProof pressureMaximum operating pressure Regulating pressure range ARJ1020F DescriptionManifold basePart no.ARJM10-4, -6, -10M5ARJ 2010Port sizeOptionM5M5 x 0.804Applicable tubing O.D.04 4 mm 066 mm20Elbow type10.2 MPa settingBody sizeMiniature regulator Piping10M5How to OrderAccessory (Option)/Part No.Max. effective area (OUT Ǟ IN)ø6ø40.0160.015M5 (Male thread)Air 1.2 MPa 0.02 MPa 1.8 mm 20.8 MPa 0.1 to 0.7 MPa0.2 MPa setting 0.05 to 0.2 MPa–5 to 60°C (No freezing)Relieving typeNylon, Soft nylon, Polyurethane1With One-touch fittingFNote)Note) Be sure to note the maximum operating pressure for soft nylon and polyurethane. (Refer to Best Pneumatics Vol. 15.)Inlet pressure: 0.7 MPaPressure Characteristics FlowCharacteristicsConditions (Initial setting)Inlet pressure: 0.7 MPaOutlet pressure: 0.2 MPa Flow rate: 10 l /min (ANR)ARJ1020F-M5-06ARJ1020F-M5-04ARJM10-6Note 1)Compared with standardspecifications, its adjusting spring has only been changed. It is not the product which does not allow the pressure more than 0.2 MPa. Adjusting spring is not replaceable.íCompact and lightweight (16 g)íLow cracking pressure 0.02 MPaStandard model equipped with backflow function14-4-4C o u r t e s y o f C M A /F l o d y n e /H y d r a d y n e ▪ M o t i o n C o n t r o l ▪ H y d r a u l i c ▪ P n e u m a t i c ▪ E l e c t r i c a l ▪ M e c h a n i c a l ▪ (800) 426-5480 ▪ w w w .c m a f h .c o mB dimensionARJM10-4ARJM10-6ARJM10-10A dimension 90130210Stations Manifold base part no. 4 610Construction/Dimensions1.Set up the regulator while verifying thepressure that is indicated on the inlet and the outlet pressure gauges. Turning the handle excessively could damage the internal parts.1.Release the lock to adjust the pressure. After the adjustment, engage the lock. Failure to observe this procedure could damage the handle or cause the outlet pressure to fluctuate.<Lock operating method>Loosen the lock nut to unlock it, and tighten it to lock it.2.check regulator by installing it between solenoid valve and actuator.Be sure to read before handling.Refer to pages 14-21-3 to 14-21-4 for Safety Instructions and Common Precautions.Lock nut M8 X 0.75Panel screwMAX. 2.5tApplicable tubing O.D. CPanel mounting hole31 (A R J 1020F -M 5-04)32 (A R J 1020F -M 5-06)(Mounting hole)IN (Common)Applicable tubing O.D. ø4, ø61.T o connect the IN side, hold the valve guide at its wrench flats (opposite side 10) and tighten it at the recommended torque of 1.5 to 2 N·m.Excessive torque or holding it at an area other than the specified portion may result in a malfunction.2.While piping to products or operating bending moment should not be applied to a product, because it may result in damage.PrecautionsWarningCaution2-ø3.5(Mounting hole)14-4-5Miniature RegulatorSeries ARJ1020FC o u r t e s y o f C M A /F l o d y n e /H y d r a d y n e ▪ M o t i o n C o n t r o l ▪ H y d r a u l i c ▪ P n e u m a t i c ▪ E l e c t r i c a l ▪ M e c h a n i c a l ▪ (800) 426-5480 ▪ w w w .c m a f h .c o m。

科学实验用品：Archimedes原理实验仪器说明书

3B SCIENTIFIC ® PHYSICS1Bedienungsanleitung04/18 ALF1 Bügel2 Hohlzylinder 3VollzylinderDas Gerät zum Archimedischen Prinzip dient zum Nachweis des Archimedischen Prinzips des Auftriebs in Flüssigkeiten. Des Weiteren ermöglicht es die Bestimmung der Dichte einer unbekannten Flüssigkeit.Das Gerät besteht aus einem Hohlzylinder mit Bügel und Haken sowie exakteingepasstem Vollzylinder mit Öse. Das Archimedische Prinzip lautet:Die Auftriebskraft F A eines Körpers in einem Medium ist genau so groß wie die Gewichts-kraft F G des vom Körper verdrängten Medi-ums; F A = F G .Das Archimedische Prinzip gilt in Flüssigkeiten und Gasen.Da das Volumen V F der durch einen Körper verdrängten Flüssigkeit gleich dem Volumendes Körpers V K ist, gilt für die Masse m F der Flüssigkeit mit der Dichte ρ: m F = ρ V K(1)Das Gewicht F G der verdrängten Flüssigkeit entspricht dem Produkt aus deren Masse m F und der Fallbeschleunigung g : F G = g m F (2) Für die Auftriebskraft F A gilt deshalb:F A = ρ g V K(3)Die Dichte ρ einer unbekannten Flüssigkeit ergibt sich dann aus:VF A=ρ(4)Vollzylinder: Abmessungen: ca. 44 mm x 38 mm Ø Volumen: ca. 50 cm 3Gesamtabmessungen: ca. 54 x 191 mm 23B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Deutschland • Technische Änderungen vorbehalten © Copyright 2018 3B Scientific GmbH4.1 Bestätigung des Archimedischen Prin-zipsZusätzlich benötigte Geräte: 1 Kraftmesser 250 g / 2,5 N 1003370 1 Überlaufgefäß 1003518 1 Becherglas aus 1002872 1 Stativfuß1001044 1 Stativstange, 750 mm 1002935 1 Muffe mit Haken 1002828∙Stativ aufbauen und Kraftmesser an den Haken hängen.∙ Vollzylinder an den Hohlzylinder und beidean den Kraftmesser hängen. ∙ Gewicht ablesen und notieren.∙ Überlaufgefäß darunter stellen und so weitmit Wasser befüllen, dass gerade kein Wasser mehr überläuft.∙ Becherglas neben das Überlaufgefäß plat-zieren, so dass das überlaufende Wasser aufgefangen werden kann.∙ Kraftmesser soweit absenken, dass derVollzylinder vollständig im Wasser einge-taucht ist. Dabei das überlaufende Wasser im Becherglas auffangen.∙ Neuen Wert am Kraftmesser ablesen.Die Differenz zwischen beiden Ablesungen entspricht der Auftriebskraft F A auf den Vollzy-linder.∙ Das aufgefangene Wasser aus dem Be-cherglas in den Hohlzylinder gießen. Dabei sicherstellen, dass kein Wasser im Be-cherglas verbleibt.Der Kraftmesser zeigt wieder den ursprüngli-chen Wert an. Das Archimedische Prinzip ist damit bestätigt.4.2 Bestimmung der Dichte einer unbe-kannten Flüssigkeit Zusätzlich benötigte Geräte: 1 Lineal∙Mit dem Lineal Durchmesser d und Höhe h des Vollzylinders messen und sein Volu-men V berechnen (V = π r 2 h ).∙ Auftriebskraft F A bestimmen mit der unbe-kannten Flüssigkeit an Stelle des Wassers. ∙Dichte ρ der unbekannten Flüssigkeit mit-tels Formel 4 errechnen.Fig. 1 Experimentieraufbau。

双Mach-Zehnder光纤干涉传感系统中的偏振衰落控制

双Mach-Zehnder光纤干涉传感系统中的偏振衰落控制曾周末;张溪默;封皓;靳世久;安阳【摘要】In a dual Mach-Zehnder fiber interferometric sensing system, the high locating accuracy is hardly obtained due to the discrepancy of two detection signals resulting from polarization fading. To keep the stability of the detection signals, a method to control the polarization fading was proposed in this paper. A optical polarization model was established to analyze the origin of polarization fading in the system. It points out that the basic reason for the discrepancy of the detection signal correlation is from that the inconsistency of the polarization characteristics between two sensing fibers results in the effect of the input polarization on detection signals. Based on the analysis, the solutions of controlling the input polarization and searching for the working points of polarization state were put forward to e-liminate the polarization fading. Furthermore, the requirements of polarization control were further determined by analyzing the relation between signal correlation coefficients and two parameters of input polarization, and simulated annealing was applied to the verification of this theory. Field test results show that the algorithm can make a fast search for the working points of polarization state, and can maintain a steady signal correlation. It is proved that the polarization fading control method is feasible and effective.%针对偏振衰落现象导致信号关联的二义性使分布式双Mach-Zehnder光纤干涉传感系统难以实现高精度定位的问题,提出了一种控制偏振衰落的方法来保持系统检测信号的稳定性.利用系统的偏振模型分析了偏振衰落的来源,指出传感光纤偏振特性的不一致使系统检测信号对输入偏振态敏感是造成信号相关性恶化的根本原因,据此提出控制输入偏振态、搜索偏振态工作点的抗偏振衰落思想.在此基础上通过分析输入偏振态的两个参量对信号相关系数的作用进一步明确了偏振控制对算法的要求,并利用模拟退火算法进行了验证.现场实验表明,该算法可快速搜索偏振态工作点,持续稳定系统检测信号的相关性；结果证实了提出的偏振衰落控制方法可行且有效.【期刊名称】《光学精密工程》【年(卷),期】2012(020)003【总页数】9页(P468-476)【关键词】相干光学;Mach-Zehnder干涉仪;干涉传感;偏振衰落;偏振控制;相关系数;模拟退火算法【作者】曾周末;张溪默;封皓;靳世久;安阳【作者单位】天津大学精密测试技术及仪器国家重点实验室,天津300072;天津大学精密测试技术及仪器国家重点实验室,天津300072;天津大学精密测试技术及仪器国家重点实验室,天津300072;天津大学精密测试技术及仪器国家重点实验室,天津300072;天津大学精密测试技术及仪器国家重点实验室,天津300072【正文语种】中文【中图分类】TH744.3;O436.31 引言在油气管道安全监测系统和现代安全防范系统中，入侵行为的实时检测及其精确定位具有重要的现实意义。

高速平板边界层中定常条带的前缘感受性

高速平板边界层中定常条带的前缘感受性
刘洋;赵磊
【期刊名称】《空气动力学学报》
【年(卷),期】2024(42)4
【摘要】来流湍流度较高时,自由流涡波可在边界层内激发流向条带结构,并引起边界层的旁路(bypass)转捩。

本文采用调和线性化Navier-Stokes方程(harmonic linearized Navier-Stokes,HLNS)方法模拟平板边界层条带对自由流涡波的前缘感受性,并通过直接数值模拟验证了HLNS方法的可靠性。

针对马赫数4.8的高速平
板边界层,分析了零频涡波激发定常条带的前缘感受性过程及定常条带的演化规律。

研究结果表明,边界层外的自由流涡扰动对边界层条带的发展存在持续的激励作用;
对于固定展向波数的自由流涡波,法向波数为0时激发的条带幅值最大;自由流涡波的法向波数在小于临界角度时仅影响条带的幅值,而不影响条带扰动的形函数剖面。

随着当地雷诺数的增加,条带的幅值演化和形函数剖面呈现出很好的相似性;当地无
量纲展向波数β=0.18时,归一化幅值最大。

【总页数】14页(P14-26)
【作者】刘洋;赵磊
【作者单位】天津大学力学系;天津市现代工程力学重点实验室
【正文语种】中文
【中图分类】V211;V411;O357.4
【相关文献】
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2.前缘曲率变化对平板边界层感受性问题的影响
3.无限薄平板边界层前缘感受性过程的数值研究∗
4.前缘曲率对三维边界层内被激发出非定常横流模态的影响研究
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