A Tour of nonlinear anlysis

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生态足迹概念及在国外的应用

生态足迹概念及其在国外的应用黄宁郭玥锋（奥克兰大学建筑与规划学院, 新西兰奥克兰1004）摘要本文分为两部分，第一部分详细介绍了生态足迹概念的产生、发展和计算方法；第二部分从地域规模（宏观）和具体学科分类（微观）两种情形下介绍了生态足迹在国外的应用。

该文目的在于使读者能够对生态足迹概念有一个较清晰的了解，并且知道其广泛的适用性，同时也为国内生态足迹概念研究人员提供相应的国外在此领域的研究和文献线索。

关键词生态足迹概念国外应用The Conception and Overseas Application of Ecological FootprintHUANG Ning GUO Yue-fengSchool of Architecture and Planning, University of Auckland１Auckland City, New Zealand, 1004AbstractThis paper includes two sections. The first section introduces the origination, the development, and the counting method of Ecological Footprint in detail. The second section articulates the comprehensive application of Ecological Footprint overseas according to the group categorized by different geographic levels and the group categorized by various concrete disciplines. The paper aims to transmit some unambiguous information about Ecological Footprint to readers as well as leading them to understand both the conception of Ecological Footprint and its general availability in practice. Moreover, the paper can provide １黄宁（1971-），男，河南开封人，高级工程师，新西兰奥克兰大学博士研究生；主要研究方向为城市建筑和交通的可持续发展性。

Generalized network design problems

Generalized Network Design ProblemsbyCorinne Feremans1,2Martine Labb´e1Gilbert Laporte3March20021Institut de Statistique et de Recherche Op´e rationnelle,Service d’Optimisation,CP210/01, Universit´e Libre de Bruxelles,boulevard du Triomphe,B-1050Bruxelles,Belgium,e-mail: mlabbe@smg.ulb.ac.be2Universiteit Maastricht,Faculty of Economics and Business Administration Depart-ment,Quantitative Economics,P.O.Box616,6200MD Maastricht,The Netherlands,e-mail:C.Feremans@KE.unimaas.nl3Canada Research Chair in Distribution Management,´Ecole des Hautes´Etudes Com-merciales,3000,chemin de la Cˆo te-Sainte-Catherine,Montr´e al,Canada H3T2A7,e-mail: gilbert@crt.umontreal.ca1AbstractNetwork design problems consist of identifying an optimal subgraph ofa graph,subject to side constraints.In generalized network design prob-lems,the vertex set is partitioned into clusters and the feasibility conditionsare expressed in terms of the clusters.Several applications of generalizednetwork design problems arise in theﬁelds of telecommunications,trans-portation and biology.The aim of this review article is to formally deﬁnegeneralized network design problems,to study their properties and to pro-vide some applications.1IntroductionSeveral classical combinatorial optimization problems can be cast as Network Design Problems(NDP).Broadly speaking,an NDP consists of identifying an optimal subgraph F of an undirected graph G subject to feasibility conditions. Well known NDPs are the Minimum Spanning Tree Problem(MSTP),the Trav-eling Salesman Problem(TSP)and the Shortest Path Problem(SPP).We are interested here in Generalized NDPs,i.e.,in problems where the vertex set of G is partitioned into clusters and the feasibility conditions are expressed in terms of the clusters.For example,one may wish to determine a minimum length tree spanning all the clusters,a Hamiltonian cycle through all the clusters,etc.Generalized NDPs are important combinatorial optimization problems in their own right,not all of which have received the same degree of attention by operational researchers.In order to solve them,it is useful to understand their structure and to exploit the relationships that link them.These problems also underlie several important applications areas,namely in theﬁelds of telecommu-nications,transportation and biology.Our aim is to formally deﬁne generalized NDPs,to study their properties and to provide examples of their applications.We willﬁrst deﬁne an uniﬁed notational framework for these problems.This will be followed by complexity results and by the study of seven generalized NDPs.2Deﬁnitions and notationsAn undirected graph G=(V,E)consists of aﬁnite non-empty vertex set V= {1,...,n}and an edge set E⊆{{i,j}:i,j∈V}.Costs c i and c ij are assigned to vertices and edges respectively.Unless otherwise speciﬁed,c i=0for i∈V and c ij≥0for{i,j}∈E.We denote by E(S)={{i,j}∈E:i,j∈S},the subset of edges having their two end vertices in S⊆V.A subgraph F of G is denoted2by F=(V F,E F),V F⊆V,E F⊆E(V F),and its cost c(F)is the sum of its vertex and edge costs.It is convenient to deﬁne an NDP as a problem P associated with a subset of terminal vertices T⊆V.A feasible solution to P is a subgraph F=(V F,E F),where T⊆V F,satisfying some side constraints.If T=V,then the NDP is spanning;if T⊂V,it is non-spanning.Let G(T)=(T,E(T))and denote by F P(T)the subset of feasible solutions to the spanning problem P de-ﬁned on the graph G(T).Let S⊆V be such that S∩T=∅,and denote by F P(T,S)the set of feasible solutions of the non-spanning problem P on graph G(S∪T)that spans T,and possibly some vertices from S.In this framework,feasible NDP solutions correspond to a subset of edges satisfying some constraints.Natural spanning NDPs are the following.1.The Minimum Spanning Tree Problem(MSTP)(see e.g.,Magnanti andWolsey[45]).The MSTP is to determine a minimum cost tree on G that includes all the vertices of V.This problem is polynomially solvable.2.The Traveling Salesman Problem(TSP)(see e.g.,Lawler,Lenstra,RinnooyKan and Shmoys[42]).The TSP consists ofﬁnding a minimum cost cycle that passes through each vertex exactly once.This problem is N P-hard.3.The Minimum Perfect Matching Problem(MPMP)(see e.g.,Cook,Cun-ningham,Pulleyblank and Schrijver[8]).A matching M⊆E is a subset of edges such that each vertex of M is adjacent to at most one edge of M.A perfect matching is a matching that contains all the vertices of G.The problem consists ofﬁnding a perfect matching of minimum cost.This problem is polynomial.4.The Minimum2-Edge-Connected Spanning Network(M2ECN)(see e.g.,Gr¨o tschel,Monma and Stoer[26]and Mahjoub[46].The M2ECN consists ofﬁnding a subgraph with minimal total cost for which there exists two edge-disjoint paths between every pair of vertices.5.The Minimum Clique Problem(MCP).The MCP consists of determining aminimum total cost clique spanning all the vertices.This problem is trivial since the whole graph corresponds to an optimal solution.We also consider the following two non-spanning NDPs.1.The Steiner Tree Problem(STP)(see Winter[61]for an overview).TheSTP is to determine a tree on G that spans a set T of terminal vertices at minimum cost.A Steiner tree may contain vertices other than those of T.These vertices are called the Steiner vertices.This problem is N P-hard.32.The Shortest Path Problem(SPP)(see e.g.,Ahuja,Magnanti and Orlin[1]).Given an origin o and a destination d,o,d∈V,the SPP consists of deter-mining a path of minimum cost from o to d.This problem is polynomially solvable.It can be seen as a particular case of the STP where T={o,d}.In generalized NDPs,V is partitioned into clusters V k,k∈K.We now formally deﬁne spanning and non-spanning generalized NDPs.Deﬁnition1(“Exactly”generalization of spanning problem).Let G= (V,E)be a graph partitioned into clusters V k,k∈K.The“exactly”generaliza-tion of a spanning NDP P on G consists of identifying a subgraph F=(V F,E F) of G yieldingmin{c(F):|V F∩V k|=1,F∈F P( k∈K(V F∩V k))}.In other words,F must contain exactly one vertex per cluster.Two diﬀer-ent generalizations are considered for non-spanning NDPs.Deﬁnition2(“Exactly”generalizations of non-spanning problem).Let G=(V,E)be a graph partitioned into clusters V k,k∈K,and let{K T,K S}be a partition of K.The“exactly”T-generalization of a non-spanning problem NDP P on G consists of identifying a subgraph F=(V F,E F)of G yielding min{c(F):|V F∩V k|=1,k∈K T,F∈F P( k∈K T(V F∩V k), k∈K S V k)}.The“exactly”S-generalization of a non-spanning problem NDP P on G consists of identifying a subgraph F=(V F,E F)of G yieldingmin{c(F):|V F∩V k|=1,k∈K S,F∈F P( k∈K T V k, k∈K S(V F∩V k))}.In other words,in the“exactly”T-generalization,F must contain exactly one vertex per cluster V k with k∈K T,and possibly other vertices in k∈K S V k.In the“exactly”S-generalization,F must contain exactly one vertex per cluster V k with k∈K S,and all vertices of k∈K T V k.We can replace|V F∩V k|=1in the above deﬁnitions by|V F∩V k|≥1 or|V F∩V k|≤1,leading to the“at least”version or“at most”version of the generalization.The“exactly”,“at least”and“at most”versions of a generalized NDP P are denoted by E-P,L-P and M-P,respectively.In the“at most”and in the“exactly”versions,intra-cluster edges are neglected.In this case,we call the graph G,|K|-partite complete.In the“at least”version the intra-cluster edges are taken into account.43Complexity resultsWe provide in Tables1and2the complexity of the generalized versions in their three respective forms(“exactly”,“at least”and“at most”)for the seven NDPs considered.Some of these combinations lead to trivial problems.Obviously,if a classical NDP is N P-hard,its generalization is also N P-hard.The indication“∅is opt”means that the empty set is feasible and is optimal for the correspond-ing problem.References about complexity results for the classical version of the seven problems considered can be found in Garey and Johnson[20].As can be seen from Table2,two cases of the generalized SPP are N P-hard by reduction from the Hamiltonian Path Problem(see Garey and Johnson[20]). Li,Tsao and Ulular[43]show that the“at most”S-generalization is polynomial if the shrunk graph is series-parallel but provide no complexity result for the gen-eral case.A shrunk graph G S=(V S,E S)derived from a graph G partitioned into clusters is deﬁned as follows:V S contains one vertex for each cluster of G, and there exists an edge in E S whenever an edge between the two corresponding clusters exists in G.An undirected graph is series-parallel if it is not contractible to K4,the complete graph on four vertices.A graph G is contractible to an-other graph H if H can be obtained from G by deleting and contracting edges. Contracting an edge means that its two end vertices are shrunk and the edge is deleted.We now provide a short literature review and applications for each of the seven generalized NDPs considered.Table1:Complexity of classical and generalized spanning NDPs Problem MSTP TSP MPMP M2ECN MCP Classical Polynomial N P-hard Polynomial N P-hard Trivial,polynomial Exactly N P-hard[47]N P-hard Polynomial N P-hard N P-hard(with vertexcost)[35]At least N P-hard[31]N P-hard Polynomial N P-hard Equivalent toexactlyAt most∅is opt∅is opt∅is opt∅is opt∅is opt5Table2:Complexity of classical and generalized non-spanning NDPsProblem STP SPPClassical N P-hard PolynomialExactly T-generalization N P-hard PolynomialExactly S-generalization N P-hard N P-hardAt least T-generalization N P-hard PolynomialAt least S-generalization N P-hard N P-hardAt most T-generalization∅is opt∅is optAt most S-generalization N P-hard Polynomial if shrunk graphis series-parallel[43]4The generalized minimum spanning tree prob-lemThe Generalized Minimum Spanning Tree Problem(E-GMSTP)is the problemofﬁnding a minimum cost tree including exactly one vertex from each vertexset from the partition(see Figure1a for a feasible E-GMSTP solution).Thisproblem was introduced by Myung,Lee and Tcha[47].Several formulations areavailable for the E-GMSTP(see Feremans,Labb´e and Laporte[17]).The Generalized Minimum Spanning Tree Problem in its“at least”version(L-GMSTP)is the problem ofﬁnding a minimum cost tree including at least onevertex from each vertex set from the partition(see Figure1b for a feasible solu-tion of L-GMSTP).This problem was introduced by Ihler,Reich and Widmayer[31]as a particular case of the Generalized Steiner Tree Problem(see Section9)under the name“Class Tree Problem”.Dror,Haouari and Chaouachi[11]showthat if the family of clusters covers V without being pairwise disjoint,then theL-GMSTP deﬁned on this family can be transformed into the original L-GMSTPon a graph G′obtained by substituting each vertex v∈ ℓ∈L Vℓ,L⊆K by|L| copies vℓ∈Vℓ,ℓ∈L,and adding edges of weight zero between each pair of thesenew vertices(clique of weight zero between vℓforℓ∈L).This can be done aslong as there is noﬁxed cost on the vertices,and this transformation does nothold for the“exactly”version of the problem.Applications modeled by the E-GMSTP are encountered in telecommuni-cations,where metropolitan and regional networks must be interconnected by atree containing a gateway from each network.For this internetworking,a vertexhas to be chosen in each local network as a hub and the hub vertices must be con-nected via transmission links such as opticalﬁber(see Myung,Lee and Tcha[47]).6Figure 1a: E−GMSTP Figure 1b: L−GMSTPFigure1:Feasible GMSTP solutionsThe L-GMSTP has been used to model and solve an important irrigation network design problem arising in desert environments,where a set of|K|poly-gon shaped parcels share a common source of water.Each parcel is represented by a cluster made up of the polygon vertices.Another cluster corresponds to the water source vertex.The problem consists of designing a minimal length irriga-tion network connecting at least one vertex from each parcel to the water source. This irrigation problem can be modeled as an L-GMSTP as follows.Edges corre-spond to the boundary lines of the parcel.The aim is to construct a minimal cost tree such that each parcel has at least one irrigation source(see Dror,Haouari and Chaouachi[11]).Myung,Lee and Tcha[47]show that the E-GMSTP is strongly N P-hard, using a reduction from the Node Cover Problem(see Garey and Johnson[20]). These authors also provide four integer linear programming formulations.A branch-and-bound method is developed and tested on instances involving up to 100vertices.For instances containing between120and200vertices,the method is stopped before theﬁrst branching.The lower bounding procedure is a heuris-tic method which approximates the linear relaxation associated with the dual of a multicommodityﬂow formulation for the E-GMSTP.A heuristic algorithm ﬁnds a primal feasible solution for the E-GMSTP using the lower bound.The branching strategy performed in this method is described in Noon and Bean[48].A cluster isﬁrst selected and branching is performed on each vertex of this cluster.In Faigle,Kern,Pop and Still[14],another mixed integer formulation for the E-GMSTP is given.The linear relaxation of this formulation is computed for a set of12instances containing up to120vertices.This seems to yield an7optimal E-GMSTP solution for all but one instance.The authors also use the subpacking formulation from Myung,Lee and Tcha[47]in which the integrality constraints are kept and the subtour constraints are added dynamically.Three instances containing up to75vertices are tested.A branch-and-cut algorithm for the same problem is described in Feremans[15].Several families of valid inequalities for the E-GMSTP are introduced and some of these are proved to be facet deﬁputational results show that instances involving up to200vertices can be solved to optimality using this method.A comparison with the computational results obtained in Myung,Lee and Tcha[47]shows that the gap between the lower bound and the upper bound obtained before branching is reduced by10%to20%.Pop,Kern and Still[51]provide a polynomial approximation algorithm for the E-GMSTP.Its worst-case ratio is bounded by2ρif the cluster size is bounded byρ.This algorithm is derived from the method described in Magnanti and Wolsey[45]for the Vertex Weighted Steiner Tree Problem(see Section9).Ihler,Reich,Widmayer[31]show that the decision version of the L-GMSTP is N P-complete even if G is a tree.They also prove that no constant worst-case ratio polynomial-time algorithm for the L-GMSTP exists unless P=N P,even if G is a tree on V with edge lengths1and0.They also develop two polynomial-time heuristics,tested on instances up to250vertices.Finally,Dror,Haouari and Chaouachi[11]provide three integer linear programming formulations for the L-GMSTP,two of which are not valid(see Feremans,Labb´e and Laporte[16]). The authors also describeﬁve heuristics including a genetic algorithm.These heuristics are tested on20instances up to500vertices.The genetic algorithm performs better than the other four heuristics.An exact method is described in Feremans[15]and compared to the genetic algorithm in Dror,Haouari and Chaouachi[11].These results show that the genetic algorithm is time consuming compared to the exact approach of Feremans[15].Moreover the gap between the upper bound obtained by the genetic algorithm and the optimum value increases as the size of the problem becomes larger.5The generalized traveling salesman problem The Generalized Traveling Salesman Problem,denoted by E-GTSP,consists of ﬁnding a least cost cycle passing through each cluster exactly once.The sym-metric E-GTSP was introduced by Henry-Labordere[28],Saskena[56]and Sri-vastava,Kumar,Garg and Sen[60]who proposed dynamic programming formu-lations.Theﬁrst integer linear programming formulation is due to Laporte and Nobert[40]and was later enhanced by Fischetti,Salazar and Toth[18]who in-8troduced a number of facet deﬁning valid inequalities for both the E-GTSP and the L-GTSP.In Fischetti,Salazar and Toth[19],a branch-and-cut algorithm is developed,based on polyhedral results developed in Fischetti,Salazar and Toth [18].This method is tested on instances whose edge costs satisfy the triangular inequality(for which E-GTSP and L-GTSP are equivalent).Moreover heuristics producing feasible E-GTSP solutions are provided.Noon[50]has proposed several heuristics for the GTSP.The most sophis-ticated heuristic published to date is due to Renaud and Boctor[53].It is a generalization of the heuristic proposed in Renaud,Boctor and Laporte[54]for the classical TSP.Snyder and Daskin[59]have developed a genetic algorithm which is compared to the branch-and-cut algorithm of Fischetti,Salazar and Toth[19]and to the heuristics of Noon[50]and of Renaud and Boctor[53].This genetic algorithm is slightly slower than other heuristics,but competitive with the CPU times obtained in Fischetti,Salazar and Toth[19]on small instances, and noticeably faster on the larger instances(containing up to442vertices).Approximation algorithms for the GTSP with cost function satisfying the triangle inequality are described in Slav´ık[58]and in Garg,Konjevod and Ravi [21].A non-polynomial-time approximation heuristic derived from Christoﬁdes heuristic for the TSP[7]is presented in Dror and Haouari[10];it has a worst-case ratio of2.Transformations of the GTSP instances into TSP instances are studied in Dimitrijevi´c and Saric[9],Laporte and Semet[41],Lien,Ma and Wah[44],Noon and Bean[49].According to Laporte and Semet[41],they do not provide any signiﬁcant advantage over a direct approach since the TSP resulting from the transformation is highly degenerate.The GTSP arises in several application contexts,several of which are de-scribed in Laporte,Asef-Vaziri and Sriskandarajah[38].These are encountered in post box location(Labb´e and Laporte[36])and in the design of postal deliv-ery routes(Laporte,Chapleau,Landry,and Mercure[39]).In theﬁrst problem the aim is to select a post box location in each zone of a territory in order to achieve a compromise between user convenience and mail collection costs.In the second application,collection routes must be designed through several post boxes at known locations.Asef-Vaziri,Laporte,and Sriskandarajah[3]study the problem of optimally designing a loop-shaped system for material transportation in a factory.The factory is partitioned into|K|rectilinear zones and the loop must be adjacent to at least one side of each zone,which can be formulated as a GTSP.The GTSP can also be used to model a simple case of the stochastic vehicle routing problem with recourse(Dror,Laporte and Louveaux[12])and some families of arc routing problems(Laporte[37]).In the latter application,a9symmetric arc routing problem is transformed into an equivalent vertex routing problem by replacing edges by vertices.Since the distance from edge e1to edge e2depends on the traversal direction,each edge is represented by two vertices, only one of which is used in the solution.This gives rise to a GTSP.6The generalized minimum perfect matching problemThe E-GMPMP and L-GMPMP are polynomial.Indeed,the E-GMPMP remains a classical MPMP on the shrunk graph,where c kℓ:=min{c ij:i∈V k,j∈Vℓ}for {k,ℓ}∈E S.Moreover the L-GMPMP can be reduced to the E-GMPMP.7The generalized minimum2-edge-connected network problemThe Generalized Minimum Cost2-Edge-Connected Network Problem(E-G2ECN) consists ofﬁnding a minimum cost2-edge-connected subgraph that contains ex-actly one vertex from each cluster(Figure2).Figure2:A feasible E-G2ECN solutionThis problem arises in the context of telecommunications when copper wire is replaced with high capacity opticﬁber.Because of its high capacity,this new technology allows for tree-like networks.However,this new network becomes failure-sensitive:if one edge breaks,all the network is disconnected.To avoid this situation,the network has to be reliable and must fulﬁll survivability condi-tions.Since two failures are not likely to occur simultaneously,it seems reasonable to ask for a2-connected network.10This problem is a generalization of the GMSTP.Local networks have to be interconnected by a global network;in every local network,possible locations for a gate(location where the global network and local networks can be intercon-nected)of the global network are given.This global network has to be connected, survivable and of minimum cost.The E-G2ECNP and the L-G2ECNP are studied in Huygens[29].Even when the edge costs satisfy the triangle inequality,the E-G2ECNP and the L-G2ECNP are not equivalent.These problems are N P-hard.There cannot exist a polynomial-time heuristic with bounded worst-case ratio for E-G2ECNP.In Huy-gens[29],new families of facet-deﬁning inequalities for the polytope associated with L-G2ECNP are provided and heuristic methods are described.8The generalized minimum clique problemIn the Generalized Minimum Clique Problem(GMCP)non-negative costs are associated with vertices and edges and the graph is|K|-partite complete.The GMCP consists ofﬁnding a subset of vertices containing exactly one vertex from each cluster such that the cost of the induced subgraph(the cost of the selected vertices plus the cost of the edges in the induced subgraph)is minimized(see Figure3).Figure3:A feasible GMSCP solutionThe GMCP appears in the formulation of particular Frequency Assignment Problems(FAP)(see Koster[34]).Assume that“...we have to assign a frequency to each transceiver in a mobile telephone network,a vertex corresponds to a transceiver.The domain of a vertex is the set of frequencies that can be assigned to that transceiver.An edge indicates that communication from one transceiver may interfere with communication from the other transceiver.The penalty of an11edge reﬂects the priority with which the interference should be avoided,whereas the penalty of a vertex can be seen as the level of preference for the frequen-cies.”(Koster,Van Hoesel and Kolen[35]).The GMCP can also be used to model the conformations occurring in pro-teins(see Althaus,Kohlbacher,Lenhof and M¨u ller[2]).These conformations can be adequately described by a rather small set of so-called rotamers for each amino-acid.The problem of the prediction of protein complex from the structures of its single components can then be reduced to the search of the set of rotamers, one for each side chain of the protein,with minimum energy.This problem is called the Global Minimum Energy Conformation(GMEC).The GMEC can be formulated as follows.Each residue side chain of the protein can take a number of possible rotameric states.To each side chain is associated a cluster.The vertices of this cluster represent the possible rotameric states for this chain.The weight on the vertices is the energy associated with the chain in this rotameric state. The weight on the edges is the energy coming from the combination of rotameric states for diﬀerent side chains.The GMCP is N P-hard(Koster,Van Hoesel and Kolen[35]).Results of polyhedral study for the GCP were embedded in a cutting plane approach by these authors to solve diﬃcult instances of frequency assignment problems. The structure of the graph in the frequency assignment application is exploited using tree decomposition approach.This method gives good lower bounds for diﬃcult instances.Local search algorithms to solve FAP are also investigated. Two techniques are presented in Althaus,Kohlbacher,Lenhof and M¨u ller[2]to solve the GMEC:a“multi-greedy”heuristic and a branch-and-cut algorithm. Both methods are able to predict the correct complex structure on the instances tested.9The generalized Steiner tree problemThe standard generalization of the STP is the T-Generalized Steiner Tree Prob-lem in its“at least”version(L-GSTP).Let T⊆V be partitioned into clusters. The L-GSTP consists ofﬁnding a minimum cost tree of G containing at least one vertex from each cluster.This problem is also known as the Group Steiner Tree Problem or the Class Steiner Tree Problem.Figure4depicts a feasible L-GSTP solution.The L-GSTP is a generalization of the L-GMSTP since the L-GSTP deﬁned on a family of clusters describing a partition of V is a L-GMSTP.This problem was introduced by Reich and Widmayer[52].The L-GSTP arises in wire-routing with multi-port terminals in physical Very Large Scale Integration(VLSI)design.The traditional model assuming sin-12Figure4:A feasible L-GSTP solutiongle ports for each of the terminals to be connected in a net of minimum length is a case of the classical STP.When the terminal is a collection of diﬀerent pos-sible ports,so that the net can be connected to any one of them,we have an L-GSTP:each terminal is a collection of ports and we seek a minimum length net containing at least one port from each terminal group.The multiple port locations for a single terminal may also model diﬀerent choices of placing a single port by rotating or mirroring the module containing the port in the placement (see Garg,Konjevod and Ravi[21]).More detailed applications of the L-GSTP in VLSI design can be found in Reich and Widmayer[52].The L-GSTP is N P-hard because it is a generalization of an N P-hard problem.When there are no Steiner vertices,the L-GSTP remains N P-hard even if G is a tree(see Section4).This is a major diﬀerence from the classical STP(if we assume that either there is no Steiner vertices or that G is a tree,the complexity of STP becomes polynomial).Ihler,Reich and Widmayer[31]show that the graph G can be transformed(in linear time)into a graph G′(without clusters)such that an optimal Steiner tree on G′can be transformed back into an optimal generalized Steiner tree in G.Therefore,any algorithm for the STP yields an algorithm for the L-GSTP.Even if there exist several contributions on polyhedral aspects(see among others Goemans[24],Goemans and Myung[23],Chopra and Rao[5],[6])and exact methods(see for instance Koch and Martin[33])for the classical problem, only a few are known,as far as we are aware,for the L-GSTP.Polyhedral aspects are studied in Salazar[55]and a lower bounding procedure is described in Gillard and Yang[22].13A number of heuristics for the L-GSTP have been proposed.Early heuris-tics for the L-GSTP are developed in Ihler[30]with an approximation ratio of |K|−1.Two polynomial-time heuristics are tested on instances up to250vertices in Ihler,Reich and Widmayer[31],while a randomized algorithm with polylog-arithmic approximation guarantee is provided in Garg,Konjevod,Ravi[21].A series of polynomial-time heuristics are described in Helvig,Robins,Zelikovsky [27]with worst-case ratio of O(|K|ǫ)forǫ>0.These are proved to empirically outperform one of the heuristic developed in Ihler,Reich and Widmayer[31].In the Vertex Weighted Steiner Tree Problem(VSTP)introduced by Segev [57],weights are associated with the vertices in V.These weights can be negative, in which case they represent proﬁt gained by selecting the vertex.The problem consists ofﬁnding a minimum cost Steiner tree(the sum of the weights of the selected vertices plus the sum of the weights of the selected edges).This problem is a special case of the Directed Steiner Tree Problem(DSP)(see Segev[57]). Given a directed graph G=(V,A)with arc weights,aﬁxed vertex and a subset T⊆V,the DSP requires the identiﬁcation of a minimum weighted directed tree rooted at theﬁxed vertex and spanning T.The VSTP has been extensively studied(see Duin and Volgenant[13],Gorres[25],Goemans and Myung[23], Klein and Ravi[32]).As far as we know,no Generalized Vertex Weighted Steiner Tree Problem has been addressed.An even more general problem would be the Vertex Weighted Directed Steiner Tree Problem.10The generalized shortest path problemLi,Tsao and Ulular[43]describe an S-generalization of the SPP in its“at most”version(M-GSPP).Let o and d be two vertices of G and assume that V\{o,d}is partitioned into clusters.The M-GSPP consists of determining a shortest path from o to d that contains at most one vertex from each cluster.Note that the T-generalization is of no interest since it reduces to computing the shortest paths between all the pairs of vertices belonging to the two diﬀerent clusters.In the problem considered by Li,Tsao and Ulular[43],each vertex is as-signed a non-negative weight.The problem consists ofﬁnding a minimum cost path from o to d such that the total vertex weight on the path in each traversed cluster does not exceed a non-negative integerℓ(see Figure5).This problem with ℓ=1and vertex weights equal to one for each vertex coincides with the M-GSPP.The problem arises in optimizing the layout of private networks embedded in a larger telecommunication network.A vertex in V\{o,d}represents a digital cross connect center(DCS)that treats the information and insures the transmis-sion.A cluster corresponds to a collection of DCS located at the same location14。

专八翻译真题1995-2013(18年真题)

1995年英语专业八级考试--翻译部分参考译文C-E原文：简.奥斯丁的小说都是三五户人家居家度日，婚恋嫁娶的小事。

因此不少中国读者不理解她何以在西方享有那么高的声誉。

但一部小说开掘得深不深，艺术和思想是否有过人之处，的确不在题材大小。

有人把奥斯丁的作品比作越咀嚼越有味道的橄榄。

这不仅因为她的语言精彩，并曾对小说艺术的发展有创造性的贡献，也因为她的轻快活泼的叙述实际上并不那么浅白，那么透明。

史密斯夫人说过，女作家常常试图修正现存的价值秩序，改变人们对“重要”和“不重要”的看法。

也许奥斯丁的小说能教我们学会转换眼光和角度，明察到“小事”的叙述所涉及的那些不小的问题。

参考译文：However, subject matter is indeed not the decisive factor by which we judge a novel of its depth as well as (of ) its artistic appeal and ideological content (or: as to whether a novel digs deep or not or whether it exc els in artistic appeal and ideological content). Some people compare Austen’s works to olives: the more you chew them, the more tasty (the tastier) they become. This comparison is based not only on (This is not only because of ) her expressive language and her creative contribution to the development of novel writing as an art, but also on (because of ) the fact that what hides behind her light and lively narrative is something implicit and opaque (not so explicit and transparent). Mrs. Smith once observed, women writers often sought (made attempts) to rectify the existing value concepts (orders) by changing people’s opinions on what is “important” and what is not.E-C原文I, by comparison, living in my overpriced city apartment, walking to work past putrid sacks of street garbage, paying usurious taxes to local and state governments I generally abhor, I am rated middle class. This causes me to wonder, do the measurement make sense? Are we measuring only that which is easily measured--- the numbers on the money chart --- and ignoring values more central to the good life?For my sons there is of course the rural bounty of fresh-grown vegetables, line-caught fish and the shared riches of neighbours’ orchards and gardens. There is the unpaid baby-sitter for whose children my daughter-in-law baby-sits in return, and neighbours who barter their skills and labour. But more than that, how do you measure serenity? Sense if self?I don’t want to idealize life in small places. There are times when the outside world intru des brutally, as when the cost of gasoline goes up or developers cast their eyes on untouched farmland. There are cruelties, there is intolerance, there are all the many vices and meannesses in small places that exist in large cities. Furthermore, it is harder to ignore them when they cannot be banished psychologically to another part of town or excused as the whims of alien groups --- when they have to be acknowledged as “part of us.”Nor do I want to belittle the opportunities for small decencies in cities --- the eruptions of one-stranger-to-another caring that always surprise and delight. But these are,sadly,more exceptions than rules and are often overwhelmed by the awful corruptions and dangers that surround us.参考译文：对我的几个儿子来说，乡村当然有充足的新鲜蔬菜，垂钓来的鱼，邻里菜园和果园里可供分享的丰盛瓜果。

繁花读后感英文

"Blossoms," a literary masterpiece by the esteemed author ________, is an intricate tapestry of human emotions, societal complexities, and philosophical contemplations, all woven together through the vivid portrayal of life amidst a profusion of flowers. This profound narrative not only captures the essence of its characters but also offers a panoramic view of their milieu, thereby inviting readers to delve into a multi-layered exploration of the human condition. In this essay, I will embark on a comprehensive and nuanced analysis of "Blossoms," examining its themes, characterizations, symbolism, and literary techniques, with the aim of unraveling the rich tapestry of meaning that lies within.I. Themes: An Ode to Life's Contrasts and ComplexitiesAt the heart of "Blossoms" lies a profound meditation on the dualities and paradoxes that define human existence. The novel presents a vivid portrayal of the simultaneous beauty and brutality, joy and sorrow, hope and despair that coexist in our lives, much like the delicate yet resilient flowers that grace its pages. The ebb and flow of relationships, the struggle for identity, the confrontation with mortality, and the quest for meaning are recurrent motifs that underscore the book's central theme: life is an intricate blend of light and shadow, a symphony of contradictions that we must learn to embrace and navigate.One of the most striking aspects of "Blossoms" is its examination of the human capacity for resilience in the face of adversity. Through the lives of its characters, the novel illustrates how individuals can bloom even in the harshest of conditions, much like flowers that stubbornly push through concrete. This theme is poignantly captured in the character arcs of _______, who, despite being battered by life's storms, find the strength to rise, heal, and flourish anew. Their journeys serve as a testament to the indomitable human spirit and the transformative power of hope, forgiveness, and self-discovery.II. Characterizations: A Kaleidoscope of Humanityfacets of the human experience. They are neither entirely virtuous nor irredeemably flawed, reflecting the intricate shades of gray that constitute real-life personas. The author masterfully employs a technique of gradual revelation, peeling back the layers of their psyches layer by layer, allowing readers to empathize with their struggles, celebrate their triumphs, and ponder their choices.________, the protagonist, is a particularly compelling character whose journey serves as a microcosm of the novel's overarching themes. Their transformation from a timid, uncertain individual to a self-assured, resilient one mirrors the blossoming process that the book so eloquently explores. Their encounters with various supporting characters, each representing different life perspectives and challenges, further enrich the narrative, demonstrating the interconnectedness of human lives and the profound impact we have on one another.III. Symbolism: Flowers as Metaphors for LifeFlowers, as the titular motif, are employed throughout the novel as powerful symbols that resonate on multiple levels. They serve not only as visual anchors that evoke the sensory richness of the story's setting but also as profound metaphors for the human experience. Each flower species, with its distinct characteristics and life cycle, represents a particular aspect of life or a stage in a character's journey.For instance, the fragility and fleeting beauty of cherry blossoms symbolize the ephemeral nature of life and the importance of cherishing every moment. The tenacious wildflowers pushing through concrete embody the human capacity for resilience and the potential for growth even in the most adverse circumstances. The cycle of blooming, wilting, and rebirth in flowers mirrors the cycles of life, death, and renewal that the characters undergo, emphasizing the universality of these experiences.IV. Literary Techniques: Crafting a Lyrical Narrative"Blossoms" is a triumph of literary craftsmanship, showcasing the author'smoving and intellectually stimulating. The poetic prose, replete with vivid imagery and evocative metaphors, immerses readers in the story's world, allowing them to viscerally experience the characters' emotions and the ambiance of their surroundings.The nonlinear narrative structure, with its seamless interweaving of past and present, memory and reality, adds depth and complexity to the story, mirroring the labyrinthine nature of human memory and the indelible influence of the past on the present. The use of foreshadowing, metaphorical dream sequences, and recurring motifs further enhances the novel's thematic coherence and imbues it with a sense of inevitability and purpose.V. Conclusion: A Profound Meditation on the Human ConditionIn conclusion, "Blossoms" is a literary tour de force that transcends mere storytelling, offering a profound and nuanced meditation on the complexities, contrasts, and inherent beauty of the human experience. Through its richly drawn characters, symbolic use of flowers, and masterful literary techniques, the novel invites readers on a deeply introspective journey, encouraging them to contemplate their own lives and the world around them with renewed empathy, wisdom, and wonder.By embracing life's contradictions and celebrating the resilience of the human spirit, "Blossoms" ultimately affirms the inherent value and dignity of every life, regardless of the challenges it may face. It is a testament to the transformative power of literature, serving as a reminder that even in the darkest of times, there exists the potential for growth, healing, and the blossoming of new beginnings.This essay, while extensive, has merely scratched the surface of the profound depths and intricate layers that "Blossoms" offers. It is a novel that rewards repeated readings, each time revealing new insights, connections, and nuances that attest to its status as a truly remarkable work of literature.。

通过看《热辣滚烫》观后感做法英文作文

通过看《热辣滚烫》观后感做法英文作文全文共6篇示例，供读者参考篇1My Scorching Hot Takeaways from "Hot, Hot, Hot"As a high school student, I don't often get the chance to watch foreign films. My friends and I usually stick to the latest Hollywood blockbusters or mindless comedies. However, when my English teacher assigned us to watch the Thai romantic comedy "Hot, Hot, Hot" and write a critical analysis, I was intrigued. I had never experienced cinema from Southeast Asia before. Little did I know just how impactful this movie would be."Hot, Hot, Hot" follows the story of seven friends living in Bangkok trying to navigate the complexities of modern relationships. The members of the friend group could not be more different - from suave ladykillers to awkward nerds, party girls to career-driven women. Yet they all share one burning thread that ties their stories together: the scalding pursuit of romance in a fast-paced city that seemingly wants them to remain single.From the very first scene, I was hooked by the crackling chemistry between the actors portraying the various friends. The dialogue was rapid-fire, filled with witty banter and brutal honesty about topics like one-night stands, open relationships, and other unorthodox dating situations. As someone who has only experienced high school romance, it was a fascinating peek into the adult world of dating that awaits after graduation.What I loved most about the movie was how it portrayed relationships in a candid, unvarnished way. The characters didn't hold back in expressing their desires, frustrations, and insecurities when it came to matters of the heart. There were no sugar-coated fairytales or idealized romantic narratives. Just real people making plenty of mistakes, feeling confused and conflicted, and trying to find genuine connection in a sea of potential partners.I could easily see reflections of people I know - friends who play the field, others who struggle with vulnerability, and plenty who fall head over heels too quickly only to get burned. The character arcs rang so true because the writers tapped into the universal struggles we all face in searching for "the one" while determining who we are and what we truly want from life partners.Speaking of wanting, one of the core themes that blazed from beginning to end was the role of physical desire in modern relationships. The characters didn't shy away from engaging in casual flings or openly discussing their bodily cravings. While some found this emphasis on sex to be too explicit, I appreciated the frank depiction of how hormones and lust influence the dating decisions of young adults.At its core, "Hot, Hot, Hot" made the case that love and lust are deeply intertwined, whether we like to admit it or not. The steamy romantic storylines showed just how combustible that chemistry can be, for better or worse. I respected that the movie didn't try to separate the physical and emotional aspects of intimacy, but rather portrayed the messy reality of how they mingle in the real world.Yet the true genius was how the different storylines converged to make profound statements about the human conditions like loneliness, self-worth, and the need to be loved for our authentic selves. Several characters had to confront the harsh truth that the endless cycle of casual hookups left them feeling empty and longing for a deeper emotional connection. Others had to overcome crippling insecurities and feelings ofunworthiness before they could open themselves up to committed relationships.By the end, each friend had sacrificed, grown, and arrived at critical junctures in their respective romantic journeys. Not every storyline had a tidy fairytale resolution, which I appreciated as a realistic portrayal of how complicated and nonlinear the quest for love can be. The final scenes felt earned, raw, and rich with wisdom about what it actually takes to find fulfillment with a partner.Overall, I came away from "Hot, Hot, Hot" appreciating how the movie captured the frenetic, thrilling, and sometimes scalding reality of dating. The overlapping storylines paid homage to just how feverishly intense the pursuit of romantic and sexual desire can be, especially for young people in a bustling urban environment.At the same time, the friendship between the core group served as an anchor and source of relatability. No matter how wild their individual romantic sagas became, they always had each other's backs and provided much-needed humor, support, and voice of reason. It reminded me of just how crucial close friends are during those chaotic years of figuring out our needs and boundaries in relationships.I'm grateful my English teacher introduced me to this refreshingly honest romantic dramedy from Thailand. "Hot, Hot, Hot" opened my eyes to different cultural perspectives while affirming many of the universal truths about dating, mating, and the scalding hot hunger for finding "the one." I may still prefer superhero movies or mindless romcoms, but I have a newfound appreciation for edgier, more grounded takes on modern love lives. Who knew getting burned by a little Thai romantic fire could leave such a lasting lesson?篇2Spicy Gourmet: A Delightful Journey of Culinary Passion and Self-DiscoveryAs a student, my life often revolves around a whirlwind of assignments, exams, and extracurricular activities, leaving little room for leisure pursuits. However, when the opportunity arose to watch the critically acclaimed film "Spicy Gourmet," I found myself unexpectedly captivated by its charming storytelling and thought-provoking themes.The movie follows the journey of Hyo-ri, a young woman who, disillusioned with her corporate job, embarks on a quest to rediscover her true passion – cooking. From the very first frames,the film immersed me in a vibrant world of tantalizing aromas, sizzling pans, and a kaleidoscope of colors that emanated from the meticulously prepared dishes.Hyo-ri's initial struggles resonated deeply with me as a student grappling with the pressures of societal expectations and the constant search for purpose. Her decision to leave the safety of her desk job and pursue her culinary dreams was both daring and inspiring, reminding me that sometimes, we must take leaps of faith to truly find fulfillment.As Hyo-ri delved deeper into the world of cooking, her dedication and unwavering commitment were trulyawe-inspiring. I found myself drawn into her journey, eagerly anticipating each new dish she would create and the lessons she would learn along the way. The film masterfully wove together the art of cooking with profound insights into personal growth, perseverance, and the pursuit of one's passions.One aspect of the film that particularly resonated with me was the emphasis on embracing cultural traditions and celebrating the rich tapestry of flavors that span across different cuisines. Hyo-ri's exploration of diverse culinary techniques and her willingness to learn from esteemed chefs of variousbackgrounds reminded me of the importance of embracing diversity and seeking knowledge from diverse sources.The film's portrayal of the culinary world was not merely a celebration of food but also a poignant exploration of human connections and relationships篇3A Sizzling Serving of Life Lessons: Reflections on "As Hot as It Gets"The silver screen has a knack for transporting us to extraordinary realms, igniting our emotions, and leaving an indelible mark on our psyches. "As Hot as It Gets," a cinematic tour de force, accomplishes precisely that, offering a tantalizing blend of humor, heartache, and hard-earned wisdom. As a student navigating the complexities of life, this film resonated with me on multiple levels, serving as a poignant reminder of the invaluable lessons that often lie beneath the surface of our everyday experiences.At the heart of the narrative is the tempestuous relationship between Jack Russo, a renowned chef wit篇4Some Like It Scorching Hot: Lessons from a Cross-Dressing ClassicAs a student constantly juggling assignments, social life, and the endless pursuit of self-discovery, I often find solace in the escapism of classic cinema. Recently, I stumbled upon the 1959 comedy "Some Like It Hot," directed by the legendary Billy Wilder, and it left an indelible mark on my psyche. This film, a masterpiece of its time, transcends the boundaries of mere entertainment and becomes a profound exploration of identity, societal norms, and the indomitable human spirit.At its core, "Some Like It Hot" revolves around the misadventures of Joe (Tony Curtis) and Jerry (Jack Lemmon), two struggling musicians who inadvertently witness the St. Valentine's Day Massacre. Forced to flee from the clutches of the mob, they devise an ingenious plan: to disguise themselves as women and join an all-female jazz band heading to Florida. What ensues is a hilarious and thought-provoking journey that challenges the very notion of gender roles and societal expectations.One of the most striking aspects of the film is its fearless commentary on gender stereotypes. Joe and Jerry, initially reluctant to embrace their feminine alter egos, gradually adaptto their new personas, shattering preconceived notions of masculinity and femininity. Their transformations are not mere physical disguises but profound explorations of the fluidity of gender expression. Through their experiences, the film subtly challenges the rigid confines of societal expectations, inviting viewers to question the very fabric of gender norms.Moreover, "Some Like It Hot" serves as a poignant reminder of the universality of human desires and emotions. Beneath the layers of comedic hijinks and mistaken identities lies a profound exploration of love, longing, and the pursuit of happiness. Joe's pursuit of Sugar Kane (Marilyn Monroe), a vivacious and alluring singer, transcends the boundaries of his assumed identity, highlighting the timeless yearning for connection and intimacy that resonates across all genders and societal constructs.Yet, the film's true brilliance lies in its ability to seamlessly blend biting social commentary with uproarious humor. Wilder's deft touch as a director ensures that the film never becomes preachy or heavy-handed, instead allowing the audience to simultaneously laugh and ponder the deeper implications of the narrative. The chemistry between Curtis, Lemmon, and Monroe is electric, with their impeccable comedic timing and charismatic performances elevating the material to new heights.As a student navigating the complexities of identity and self-discovery, "Some Like It Hot" resonates with me on a profound level. It serves as a poignant reminder that societal norms and expectations are often arbitrary constructs, and true fulfillment lies in embracing one's authentic self, regardless of societal labels or boundaries. The film's enduring popularity and cultural significance are a testament to its ability to strike a chord with audiences across generations, transcending the confines of its era and speaking to the universal human experience.Furthermore, "Some Like It Hot" has inspired me to approach my studies and personal growth with a renewed sense of open-mindedness and curiosity. Just as Joe and Jerry challenged societal norms through their daring charade, I am encouraged to question preconceived notions and embrace diverse perspectives. Whether it's exploring new fields of study, engaging in thought-provoking discussions, or simply allowing myself to be challenged by alternative viewpoints, the film has instilled in me a desire to break free from the shackles of complacency and embrace the richness of human experience.In conclusion, "Some Like It Hot" is more than just a classic comedy; it is a cultural touchstone that resonates with audiences across generations. Through its deft blend of humor and socialcommentary, the film challenges gender norms, celebrates the universality of human emotions, and invites viewers to embrace authenticity and open-mindedness. As a student on a journey of self-discovery, this film has left an indelible mark on my psyche, encouraging me to approach life with a spirit of curiosity, empathy, and a willingness to challenge societal conventions. In the words of Joe, "Nobody's perfect," and it is in embracing our imperfections and celebrating our authentic selves that we truly find fulfillment.篇5Wet Dreams: A Spicy Reflection on Youth, Desire, and Finding Your PathAs a high school student, I was first drawn to the Korean film "Haewaa" (translated as "Wet Dreams") by its provocative title and subject matter. A movie centered on the raging hormones and sexual curiosity of adolescents? Sign me up! However, what I initially expected to be a raunchy teen comedy actually turned out to be a surprisingly insightful and nuanced exploration of youth, relationships, and the turbulence of that transformative time in life.The film follows a trio of best friends - Sung-ok, Cho-ri, and Ki-ok - as they navigate the final year of high school while being constantly distracted and consumed by their newly discovered sexual urges. From obsessing over porn magazines to trying to catch glimpses of the opposite sex undressing, their hormones are raging out of control. While the characters' fixation on sex provides much of the comedic relief, the heart of the story lies in their eventually maturing perspectives on love, intimacy, and finding purpose beyond just physical desires.One of the most refreshing aspects of the film is its frank depiction of female sexuality from a decidedly female lens. Too often in media, the sexual awakening experience is depicted through the male gaze. But "Wet Dreams" puts the journey of Sung-ok, Cho-ri and Ki-ok front and center, showing the equally confusing mix of excitement and shame篇6Spicing Up Life: A Retrospective on "Hot and Spicy"As a student, I've always been drawn to films that challenge societal norms and provide a fresh perspective on the complexities of human existence. "Hot and Spicy," the latest offering from acclaimed director Alejandro Castillo, did just that– and more. This cinematic masterpiece not only sizzled with its bold exploration of themes like passion, desire, and cultural identity, but it also left me craving for a deeper understanding of life's many flavors.The story follows the intertwined lives of three generations of a Mexican-American family residing in Los Angeles. At the heart of the narrative is Abuela Rosa, a feisty matriarch whose love for traditional Mexican cuisine is matched only by her fierce determination to keep her family's heritage alive. Her daughter, Carmen, a successful businesswoman, finds herself torn between her mother's expectations and her own aspirations, while her daughter, Sophia, grapples with the complexities of navigating her bicultural identity.From the very first frame, "Hot and Spicy" immerses the viewer in a vibrant tapestry of sights, sounds, and aromas that transport us directly to the heart of East LA's bustling streets. The film's attention to detail is remarkable, with each scene meticulously crafted to capture the essence of the Latino community's rich cultural fabric. Whether it's the lively mariachi music that permeates the air or the mouthwatering close-ups of sizzling fajitas and steaming tamales, the film leaves no stoneunturned in its quest to authentically depict the lived experiences of its characters.But "Hot and Spicy" is far more than just a colorful celebration of culinary traditions; it's a poignant exploration of the generational divides that often plague immigrant families. Castillo's deft hand as a storyteller shines through in the nuanced portrayal of the tensions that arise between Abuela Rosa's unwavering commitment to her roots and Carmen's desire for assimilation. The film skillfully navigates the delicate balance between honoring one's heritage and embracing the opportunities of a new homeland, a struggle that resonates deeply with many first- and second-generation Americans.What truly sets "Hot and Spicy" apart, however, is its fearless examination of the complex themes of desire and passion. Through the character of Sophia, the film boldly tackles issues of sexual exploration, identity, and the pursuit of personal fulfillment. Castillo's unflinching lens captures the raw intensity of Sophia's journey, inviting viewers to confront their own preconceptions and biases head-on.Perhaps one of the film's greatest strengths lies in its ability to seamlessly weave together these seemingly disparate threads into a cohesive and deeply moving narrative. Just as the flavorsof a well-crafted dish meld together to create a harmonious whole, "Hot and Spicy" masterfully blends themes of cultural heritage, generational conflict, and personal growth into a rich tapestry that leaves a lasting impression.As a student, I found myself profoundly moved by the film's exploration of these universal themes. Castillo's masterful storytelling not only entertained but also challenged me to confront my own biases and preconceptions. The film's nuanced portrayal of the complexities of identity and belonging resonated deeply with my own experiences as a young person navigating the often-turbulent waters of self-discovery.But beyond its thematic richness, "Hot and Spicy" is a visual feast that left me in awe. Castillo's skilled use of vibrant colors, dynamic camerawork, and evocative lighting created a truly immersive cinematic experience. From the sun-drenched streets of East LA to the intimate confines of Abuela Rosa's kitchen, each frame was a masterclass in visual storytelling, drawing me deeper into the lives of these complex and multifaceted characters.Moreover, the film's performances were nothing short of exceptional. The ensemble cast, led by the incomparable Adriana Barraza as Abuela Rosa, delivered tour-de-force performances that breathed life into their characters' struggles and triumphs.Barraza's portrayal of the indomitable Rosa was a particular standout, imbuing the character with a depth and nuance that transcended stereotypes and clichés.As I reflect on my experience watching "Hot and Spicy," I'm struck by the power of cinema to challenge our perceptions, broaden our horizons, and ignite our imaginations. This film is a testament to the transformative potential of storytelling, reminding us that even the most familiar narratives can be imbued with new layers of meaning and significance when approached with sensitivity, creativity, and a willingness to push boundaries.In the end, "Hot and Spicy" is more than just a film; it's a celebration of life's rich tapestry, a reminder that our stories – no matter how diverse or complex – are woven together by the common threads of human experience. As a student, this film has left an indelible mark on me, inspiring me to embrace the multifaceted nature of my own identity and to approach the world with an open mind and a willingness to learn from the stories of others.Whether you're a seasoned cinephile or a casual moviegoer, "Hot and Spicy" is a cinematic experience that demands to be savored. It's a film that will linger in your mind long after thecredits roll, leaving you with a newfound appreciation for the complexities of life and a renewed hunger for the stories that have yet to be told.。

季佩玉、范烨学术英语答案

季佩玉、范烨学术英语答案2. And yet, isn't there something wonderous, — something almost inexplicable in the way your Thanksgiving weekend is made possible by the skill and labor of vast numbers of total strangers? (Line 1, Para. 4)3. ...Thanksgiving Turkey, there would be one, — or more likely, a few dozen— waiting. (Line 3, Para.6)Task 3/Formal English1. very many2. buying or selling3. a large group of4. more huge5. understand6. troubledUnit 2Language buildingTask 1:Part 1:1)无形之手；2）自由企业制度3）股东4）经济体制5）开发产品和服务6）市场力量；市场调节作用7）金融机构8）严重衰退9）破产10）mission11）stock price12）corporate motto14）maximize profits 15）financial system Part 2：1)market forces2）financial institutions 3）free enterprise system 4）deep institutions5）invisible hand6）stockholder7）profit maximization 8）economic system Task 2：1.and；2.Another；3. also；4. Not only；but；5. otherTask 31. understanding；2. agree with；3. forces… to be accepted;4. bad5. purpose7. given;8.famous.Unit 3Language buildingTask 1: collocationPart 1:1) 充满敬畏与感激；2）与外部世界隔离3）陷入绝境4）易感抑郁5）恢复体能6）界定性特征7）暂时的挫败8）不因挫败而心烦意乱9）竞选权位10）吹着欢快的曲调Part 2：1)bout 2）validated 3）squabble 4）aptitude5）platitude 6）debilitate7）reassuring 8）undermine 9）ruminate 10）martial Task 2：1.contrasting；2.in contrast；3. However；4. different；5. on the other hand6. in the opposite way7.howeverTask 31. full of；2. becomes alert and energetic3. keeping thinking about4. been left in hopelessness5. likely to suffer from6. not disturbed7. saying something that people are quite familiar with8. officially approvedUnit 4Language buildingTask 1: collocationPart 1:1. green movement2. protected areas3. extinction of animals and plants4. wild fish stocks5. make clean power6. save resources7. 培育生物多样性8. 控制污染9. 阻止对生态体系的破坏10. 扩大清洁产业11. 集体世界观12. 生态经济Part 2：1. Embedding a narrative that moves us on from protecting nature from people to protecting nature for people is an essential part of this reframing. (Para.6)If such a narrative is to gain practical effect, then looking after nature must urgently be seen as not only an environmental challenge, but also an economic one. (Para.7)The author manages to bring in a new topic and maintain coherence by repeating keys words such as narrative, nature.2. So long as we continue to travel in two directions at once, promoting environmental goals on the one hand while on the other directly contradicting that with measures to achieve more economic growth, the longer we will fail to make real progress. (Para.7)When it comes to economics and ecology there is plenty of good thinking already done. (Para.8) The author manages to bring in a new topic and maintain coherence by repeating key words such as economic, economics.Task 3 Formal language1. unchangeable; increasing2. control3. effort; charitable4. pleasant detail5. complicated6. change7. Changing8. importantUnit 5Language buildingTask 1: collocationPart 1:1. having a mind2.behave as if you understand3.what and how we know4.inside;reflects Mentalist Dbehaviorist BEpistemologist Aphenomenologist CPart 21. psychological2.spiritual3.behaviour4.phenomenologist5.perplexity6.mentallyTask 2：…,classified…This class of…The class of……a less severe label…The huge classTask 31. what we imagine about computers today2.we have broken the distinction between the first type of response3.for the sake of convenience so that it is easier to refer to the first type of response4. you have the same reason for thinking that M had a mind.5. (The reason you believe your mother has a mind is based) not on your prejudice6. as groundless as believing that computers have mindUnit 6Task 1: Specialized vocabularyPart 11. 数学化，数字处理2. 计算机辅助设计3. 统计4. 基因组学5. 运筹学6. 优化组合7. 概率8. 数据库Part 2：1. database2. CAD3. statistics4. probability5. optimization6. genomics7. mathematization8. Operations researchTask 2：1. Here are a few simple examples of prescriptive mathematics that extended from single numbers to exceedingly complex systems:…(Line1,para.8,Text A)2. Admittedly this is rather vague, but it will clarify a bit as I go on and mention a few of the manyexamples that Baker gives:…(Line 8, para.10, Text A)Task 3 Formal language1. exists2. included3. explained4. model5. get6. environment7. knowledgeable person; in which8. until now9. fix ideas of (caution) in one’s mindUnit 7Task 1: Specialized vocabularyPart 11. -h2.-f3.-a4.-j5.-i6.-b7.-d8.-g9.-c10.-ePart 2：1. To achieve professional development isimportant as a means to the end of becoming an expert and gaining more flexibility and independence2. Numerous studies over the last 30 years have suggested that personality is a powerful predictor of a person's life satisfaction3. An employee's work orientation is shaped in the first instance by their understanding of “what work is about”4. The government is trying to introduce new measures to create a better social safety net and encourage better worker pay5. Money has been used as the incentive of many intelligence contests in TV program Task 2：1. The present perfect tense（现在完成时）emphasizes that people’s conception about what money can bring them has changed greatly2. The tense switches from the present to the past to manifest that an example is given3.The tense switches between the present and the past to produce a comparison of different interpretations of a “calling”in different times Task 3 Formal language1. pour heart and soul into :spare no efforts,try one's bestwhat will stimulate\encourage a worker to try his best in making good products?2. lure：temptationgrueling：working exhaustedlyPeople are no longer so tempted by the dream of becoming rich by working exhaustedly 80 hours a week for several years in a humble position3. lowly job：humble jobrecrafted：turnedHe might be doing a humble job，but he would turn it into a great mission4. entails：requiresA career requires more devotion to work5. contributing to：being beneficial toconnotation：implicationPeople who regard their work as a calling\great mission think that what they do helps serve the public and brings benefits to our society，and therefore it's quite proper to say that a mission\calling implies something similar to religious beliefsUnit8Task 1 Specialized vocabulare1. cultural tradition 文化传统2. social stability 社会稳定3. distinct identity 鲜明特色4. edge effect 边缘效应5. organic evolution 有机界进化6. mutual respect 相互尊重7.political correctness 政治正确性anic evolution2. mutual respect3. Edge effect4. social stability5. political correctness6. cultural tradition7. distinct identityTask 2 Signpost language1. Through; through; through2. not just; but3. first4. second5. next6. final7.not only; but alsoTask 3 Formal English1. develop2. combined3. skillful performers4. obvious5. friendly6. getting rid of7. combine8. changed9. imagine10. a large number ofUnit 9Task 1 Specialized vocabulary1 D 医疗2 J 基因分型3 F 内窥镜检查4 A 生物技术5 H 诊断6 C 分子的7 I 治疗方案8 E 医生9 G 外科医生的；手术的10 B 胶囊1 diagnosis2 surgical3 Biotechnology4 healthcare5 protocols6 molecularTask 2 Signpost language1 known as2 referred to as3 call4 describe5 meanTask 3 Formal English1 increases2 marked3 arrival/ coming4 replaced5 move away6 filledUnit 10Task 1 Specialized vocabulary1 b2 k3 f4 j5 g6 i7 e8 c9 h10 a11 d1 syntactic patterns2 Language faculty3 neural system4 underlying logic5 evolutionary adaptation6 formal instruction7 mental organ8 natural selectionTask 2 Signpost language1 for2 led to3 because4 Therefore5 Therefore6 because; because7 SoTask 3 Formal English1 explanation/interpretation; impacts2 is present all over; analyze/explain/interpret亚当斯密称它为“看不见的手”导致无数人的神秘力量，各为自己的利益工作，推动结束，受益多。

无人机英语试题及答案

无人机英语试题及答案一、选择题（每题2分，共20分）1. The term "drone" in English refers to:A. 无人机B. 机器人C. 直升机D. 飞机答案：A2. Which of the following is not a common application of drones?A. 农业监测B. 物流配送C. 交通管制D. 军事侦察答案：C3. The abbreviation "UAV" stands for:A. Unmanned Aerial VehicleB. Unmanned Autonomous VehicleC. Unmanned Airborne VehicleD. Universal Aerial Vessel答案：A4. What is the basic function of a drone's GPS system?A. 导航定位B. 通讯联络C. 飞行控制D. 载荷释放答案：A5. The term "quadcopter" refers to a drone with:A. 2 propellersB. 3 propellersC. 4 propellersD. 6 propellers答案：C6. What does "FPV" stand for in drone terminology?A. First Person ViewB. Full Power ViewC. Flight Path ViewD. Forward Position View答案：A7. Which of the following is a safety feature for drones?A. 避障系统B. 增强现实C. 虚拟现实D. 人脸识别答案：A8. The term "payload" in the context of drones refers to:A. 无人机的重量B. 无人机的载重能力C. 无人机的飞行速度D. 无人机的飞行高度答案：B9. What is the main advantage of using drones for aerial photography?A. 灵活性B. 速度C. 成本D. 载重答案：A10. The "3D mapping" technology is used in drones for:A. 地形测量B. 人脸识别C. 空中表演D. 天气预报答案：A二、填空题（每题2分，共20分）1. The acronym for Unmanned Aerial Vehicle is _______.答案：UAV2. A drone that can fly autonomously without human intervention is called a _______.答案：autonomous drone3. The _______ is a device used to control a drone remotely.答案：remote controller4. The main component of a drone's propulsion system is the _______.答案：propeller5. Drones are equipped with _______ to ensure they can fly in various weather conditions.答案：stabilization system6. The _______ is the maximum distance a drone can fly from its controller.答案：range7. A drone's _______ is the maximum altitude it can reach.答案：ceiling8. The _______ is the process of programming a drone's flight path in advance.答案：waypoint planning9. The _______ is a type of camera used on drones to capture images from a high altitude.答案：aerial camera10. The _______ is the process of charging a drone's battery.答案：recharging三、简答题（每题10分，共40分）1. 请简述无人机在农业领域的应用。

高三英语学术研究方法单选题30题

高三英语学术研究方法单选题30题1. In a literature review, which of the following is the most important step?A. Collecting a large number of sourcesB. Selecting relevant and reliable sourcesC. Reading the sources quicklyD. Copying the content of the sources directly答案：B。

本题考查文献综述中最重要的步骤。

选项A 收集大量来源固然重要，但质量更关键；选项C 快速阅读来源可能会忽略重要信息；选项 D 直接复制来源内容是学术不端行为。

选项 B 选择相关可靠的来源是确保文献综述质量的关键步骤。

2. When conducting a literature review, how should you handle contradictory information from different sources?A. Ignore it and focus on the consistent informationB. Choose the information that supports your hypothesisC. Analyze and try to reconcile the differencesD. Just randomly pick one of the pieces of information答案：C。

在进行文献综述时，面对不同来源的矛盾信息，选项A 忽略它只关注一致信息可能会导致研究不全面；选项B 只选择支持假设的信息会使研究有偏差；选项 D 随机挑选信息是不科学的。

选项C 分析并尝试调和差异是正确的处理方式。

3. What is the purpose of citing sources in a literature review?A. To show off your knowledgeB. To increase the word count of your reviewC. To give credit to the original authors and support your argumentsD. To make the review look more complicated答案：C。

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0.006 u Del u 0.0300000000 0.0352941176 15.00000000% 0.0364285714 3.11418685% 0.0366812227 0.68877551% 0.0367379679 0.15445930% 0.0367507370 0.03474506% 0.0367536116 0.00782121% 0.0367542587 0.00176085% 0.0367544045 0.00039645% 0.0367544373 0.00008926% 0.0367544447 0.00002010% 0.0367544463 0.00000452% 0.0367544467 0.00000102% 0.0367544468 0.00000023% 0.0367544468 0.00000005%

Phformations upon load removal. Gross changes in geometry. Cracking, necking, thinning. Distortions in open section beams, web crippling, buckling, local yielding. Stresses in excess of the elastic limit of a material. Presence of shear bands (strain localization). Temperatures in excess of approximately 30% of the melting temperature of a material

Material nonlinearity only: Since only the constitutive relation is nonlinear, infinitesimal displacements, displacement gradients and strains are appropriate.
P
Hardening kN > 0 Slope k0
(kN = 0)
Softening kN < 0
u
Direct Substitution Method
1. 2. 3. 4.
5.
6.
Let load PA be applied to a softening spring (kN<0) Assume kN = 0 for the first iteration. Compute first approximation to displacement: u1 = PA/k0 Use u1 to compute new stiffness: k = k0 +f(u1) Compute next approximation to displacement: u2 = PA/k Generate sequence of approximations.
Sources of Nonlinearity
Material Nonlinearities: nonlinear elastic, plastic, viscoelastic, viscoplastic, etc. material characterizations. Geometric Nonlinearities: large (finite) displacements; large (finite) rotations; large (finite) strains. Other Nonlinearities: contact problems, opening/closing of gaps, sliding surfaces, “follower” forces, crack propagation.
Sequence of Operations
u1 k P u2 k ui 1 k
1 0 1 0
1 0 A
PA k N 1u1 1 u3 k0 PA k N 2u2 PA k Niui
P
PA k0
a
1
u1
u
P
PA
kN1u1
kN2u2

Linear Problem
Ku R K K (u) R R (u)
Stiffness and Forces are not functions of displacements.
Nonlinear Problem
Ku R K K (u) R R (u)
Stiffness and Forces are functions of displacements.
Nonlinear Effects
1.
2. 3.
4.
5.
Nonlinear stress-strain behavior Gaps opening or closing Mating parts 1. Stick 2. Slip Phase changes Buckling
Difficulty!

An additional nonlinearity that can be encountered in any of the above problem classes is that associated with a change, during the analysis, in nodal constraint.
3.2 1 DOF Nonlinear Problem
k u P
k k0 k N k0 kN constant function of u
Problem Statement
k0 kN u P
k f (u)
Given P find u. Assume f(u) is a known function.
a
b
1
2
u1 u2
u
P
PA
a 1
b c
2
3
u1 u2 u3
u
P
PA
a 1
b c
2
3
u1 u2 u3
uA
u
Example:
P= k 0.2000000000 0.1700000000 0.1647058824 0.1635714286 0.1633187773 0.1632620321 0.1632492630 0.1632463884 0.1632457413 0.1632455955 0.1632455627 0.1632455553 0.1632455537 0.1632455533 0.1632455532
Some Solution Methods
1. 2. 3. 4. 5.
6.
Direct Substitution Direct Substitution with Relaxation Newton-Raphson (N-R) Modified Newton-Raphson Incremental Methods Quasi-Newton Methods
Sequence of Operations
u1 k P
1 0 A
u2 k0 k N1 u3
0
k
k N2

1
PA PA PA
1
ui 1 k0 k N i

1
P
PA k0
a
1
u1
u
P
Essentially a secant method
PA k0 k0+kN1
Nonlinear problems can cost as much as 10 to 100 times as much to solve as corresponding linear problems! We often try to approximate nonlinear solutions by linear solutions
a
1 2
k0
u1 u2 u3
u
Example
i u
0.0000000000 0.0300000000 0.0345000000 0.0359512500 0.0364624619 0.0366475556 0.0367152167 0.0367400357 0.0367491511 0.0367525005 0.0367537315

Large displacements, large rotations but small strains: Displacements and displacement gradients (rotations of fibers) are large, but fiber extensions and angle changes between fibers are small; the constitutive relation can be either linear or nonlinear.
k 0.2 u P 0.006
Load - Deflection
0.020
0.018
0.015
0.013
0.010
P
0.008
0.005
0.003
0.000 0 0.01 0.02 0.03 0.04 u 0.05 0.06 0.07 0.08 0.09
Direct Substitution Alternative
计算力学 (力学系研究生)
Chapter 3
A Tour of Nonlinear Analysis
Carlos A. Felippa