WorldWideScience

Sample records for class packing problem

  1. Heuristics for Multidimensional Packing Problems

    DEFF Research Database (Denmark)

    Egeblad, Jens

    In this thesis we consider solution methods for packing problems. Packing problems occur in many different situations both directly in the industry and as sub-problems of other problems. High-quality solutions for problems in the industrial sector may be able to reduce transportation and production......) and may be defined in any number of dimensions. Solution methods are based on theory from both computational geometry and operations research. The scientific contributions of this thesis are presented in the form of six papers and a section which introduces the many problem types and recent solution...... of items. The heuristic was developed in collaboration with an industrial partner and is now being used to solve hundreds of problems every day as part of their planning process. A simple heuristic for optimizing a placement of items with respect to balance and moment of inertia is presented in the fifth...

  2. The Maximum Resource Bin Packing Problem

    DEFF Research Database (Denmark)

    Boyar, J.; Epstein, L.; Favrholdt, L.M.;

    2006-01-01

    Usually, for bin packing problems, we try to minimize the number of bins used or in the case of the dual bin packing problem, maximize the number or total size of accepted items. This paper presents results for the opposite problems, where we would like to maximize the number of bins used or...... algorithms, First-Fit-Increasing and First-Fit-Decreasing for the maximum resource variant of classical bin packing. For the on-line variant, we define maximum resource variants of classical and dual bin packing. For dual bin packing, no on-line algorithm is competitive. For classical bin packing, we find...

  3. Partial Degree Bounded Edge Packing Problem

    CERN Document Server

    Zhang, Peng

    2012-01-01

    In [1], whether a target binary string s can be represented from a boolean formula with operands chosen from a set of binary strings W was studied. In this paper, we first examine selecting a maximum subset X from W, so that for any string t in X, t is not representable by X\\{t}. We rephrase this problem as graph, and surprisingly find it give rise to a broad model of edge packing problem, which itself falls into the model of forbidden subgraph problem. Specifically, given a graph G(V;E) and a constant c, the problem asks to choose as many as edges to form a subgraph G'. So that in G', for each edge, at least one of its endpoints has degree no more than c. We call such G' partial c degree bounded. When c = 1, it turns out to be the complement of dominating set. We present several results about hardness, approximation for the general graph and efficient exact algorithm on trees. This edge packing problem model also has a direct interpretation in resource allocation. There are n types of resources and m jobs. E...

  4. Comparing Online Algorithms for Bin Packing Problems

    DEFF Research Database (Denmark)

    Epstein, Leah; Favrholdt, Lene Monrad; Kohrt, Jens Svalgaard

    2012-01-01

    The relative worst-order ratio is a measure of the quality of online algorithms. In contrast to the competitive ratio, this measure compares two online algorithms directly instead of using an intermediate comparison with an optimal offline algorithm. In this paper, we apply the relative worst......-order ratio to online algorithms for several common variants of the bin packing problem. We mainly consider pairs of algorithms that are not distinguished by the competitive ratio and show that the relative worst-order ratio prefers the intuitively better algorithm of each pair....

  5. Integrating packing and distribution problems and optimization through mathematical programming

    OpenAIRE

    Fabio Miguel; Mariano Frutos; Fernando Tohmé; Máximo Méndez

    2016-01-01

    This paper analyzes the integration of two combinatorial problems that frequently arise in production and distribution systems. One is the Bin Packing Problem (BPP) problem, which involves finding an ordering of some objects of different volumes to be packed into the minimal number of containers of the same or different size. An optimal solution to this NP-Hard problem can be approximated by means of meta-heuristic methods. On the other hand, we consider the Capacitated Vehicle Routing Proble...

  6. A SAT Encoding for Multi-dimensional Packing Problems

    Science.gov (United States)

    Grandcolas, Stéphane; Pinto, Cédric

    The Orthogonal Packing Problem (OPP) consists in determining if a set of items can be packed into a given container. This decision problem is NP-complete. Fekete et al. modelled the problem in which the overlaps between the objects in each dimension are represented by interval graphs. In this paper we propose a SAT encoding of Fekete et al. characterization. Some results are presented, and the efficiency of this approach is compared with other SAT encodings.

  7. Multi-dimensional Bin Packing Problems with Guillotine Constraints

    DEFF Research Database (Denmark)

    Amossen, Rasmus Resen; Pisinger, David

    2010-01-01

    The problem addressed in this paper is the decision problem of determining if a set of multi-dimensional rectangular boxes can be orthogonally packed into a rectangular bin while satisfying the requirement that the packing should be guillotine cuttable. That is, there should exist a series of face...... parallel straight cuts that can recursively cut the bin into pieces so that each piece contains a box and no box has been intersected by a cut. The unrestricted problem is known to be NP-hard. In this paper we present a generalization of a constructive algorithm for the multi-dimensional bin packing...

  8. The load-balanced multi-dimensional bin-packing problem

    DEFF Research Database (Denmark)

    Trivella, Alessio; Pisinger, David

    2016-01-01

    The bin-packing problem is one of the most investigated and applicable combinatorial optimization problems. In this paper we consider its multi-dimensional version with the practical extension of load balancing, i.e. to find the packing requiring the minimum number of bins while ensuring...... that the average center of mass of the loaded bins falls as close as possible to an ideal point, for instance, the center of the bin. We formally describe the problem using mixed-integer linear programming models, from the simple case where we want to optimally balance a set of items already assigned to a single...... bin, to the general balanced bin-packing problem. Given the difficulty for standard solvers to deal even with small size instances, a multi-level local search heuristic is presented. The algorithm takes advantage of the Fekete-Schepers representation of feasible packings in terms of particular classes...

  9. Heuristic Placement Routines for Two-Dimensional Bin Packing Problem

    Directory of Open Access Journals (Sweden)

    L. Wong

    2009-01-01

    Full Text Available Problem statement: Cutting and packing (C and P problems are optimization problems that are concerned in finding a good arrangement of multiple small items into one or more larger objects. Bin packing problem is a type of C AND P problems. Bin packing problem is an important industrial problem where the general objective is to reduce the production costs by maximizing the utilization of the larger objects and minimizing the material used. Approach: In this study, we considered both oriented and non-oriented cases of Two-Dimensional Bin Packing Problem (2DBPP where a given set of small rectangles (items, was packed without overlaps into a minimum number of identical large rectangles (bins. We proposed heuristic placement routines called the Improved Lowest Gap Fill, LGFi and LGFiOF for solving non-oriented and oriented cases of 2DBPP respectively. Extensive computational experiments using benchmark data sets collected from the literature were conducted to assess the effectiveness of the proposed routines. Results: The computational results were compared with some well known heuristic placement routines. The results showed that the LGFi and LGFiOF are competitive when compared with other heuristic placement routines. Conclusion: Both LGFi and LGFiOF produced better packing quality compared to other heuristic placement routines.

  10. Bin Completion Algorithms for Multicontainer Packing, Knapsack, and Covering Problems

    CERN Document Server

    Fukunaga, A S; 10.1613/jair.2106

    2011-01-01

    Many combinatorial optimization problems such as the bin packing and multiple knapsack problems involve assigning a set of discrete objects to multiple containers. These problems can be used to model task and resource allocation problems in multi-agent systems and distributed systms, and can also be found as subproblems of scheduling problems. We propose bin completion, a branch-and-bound strategy for one-dimensional, multicontainer packing problems. Bin completion combines a bin-oriented search space with a powerful dominance criterion that enables us to prune much of the space. The performance of the basic bin completion framework can be enhanced by using a number of extensions, including nogood-based pruning techniques that allow further exploitation of the dominance criterion. Bin completion is applied to four problems: multiple knapsack, bin covering, min-cost covering, and bin packing. We show that our bin completion algorithms yield new, state-of-the-art results for the multiple knapsack, bin covering,...

  11. A Personified Annealing Algorithm for Circles Packing Problem

    Institute of Scientific and Technical Information of China (English)

    ZHANGDe-Fu; LIXin

    2005-01-01

    Circles packing problem is an NP-hard problem and is difficult to solve. In this paper, a hybrid search strategy for circles packing problem is discussed. A way of generating new configuration is presented by simulating the moving of elastic objects, which can avoid the blindness of simulated annealing search and make iteration process converge fast. Inspired by the life experiences of people,an effective personified strategy to jump out of local minima is given. Based on the simulated annealing idea and personification strategy, an effective personified annealing algorithm for circles packing problem is developed. Numerical experiments on benchmark problem instances show that the proposed algorithm outperforms the best algorithm in the literature.

  12. An effective evolutionary algorithm for the multiple container packing problem

    Institute of Scientific and Technical Information of China (English)

    Sang-Moon Soak; Sang-Wook Lee; Gi-Tae Yeo; Moon-Gu Jeon

    2008-01-01

    This paper focuses on a new optimization problem, which is called "The Multiple Container Packing Problem (MCPP)" and proposes a new evolutionary approach for it. The proposed evolutionary approach uses "Adaptive Link Adjustment Evolutionary Algorithm (ALA-EA)" as a basic framework and it incorporates a heuristic local improvement approach into ALA-EA. The first step of the local search algorithm is to raise empty space through the exchange among the packed items and then to improve the fitness value through packing unpacked items into the raised empty space. The second step is to exchange the packed items and the unpacked items one another toward improving the fitness value. The proposed algorithm is compared to the previous evolutionary approaches at the benchmark instances (with the same container capacity) and the modified benchmark instances (with different container capacity) and that the algorithm is proved to be superior to the previous evolutionary approaches in the solution quality.

  13. Integrating packing and distribution problems and optimization through mathematical programming

    Directory of Open Access Journals (Sweden)

    Fabio Miguel

    2016-06-01

    Full Text Available This paper analyzes the integration of two combinatorial problems that frequently arise in production and distribution systems. One is the Bin Packing Problem (BPP problem, which involves finding an ordering of some objects of different volumes to be packed into the minimal number of containers of the same or different size. An optimal solution to this NP-Hard problem can be approximated by means of meta-heuristic methods. On the other hand, we consider the Capacitated Vehicle Routing Problem with Time Windows (CVRPTW, which is a variant of the Travelling Salesman Problem (again a NP-Hard problem with extra constraints. Here we model those two problems in a single framework and use an evolutionary meta-heuristics to solve them jointly. Furthermore, we use data from a real world company as a test-bed for the method introduced here.

  14. A Heuristic Algorithm for Solving Triangle Packing Problem

    Directory of Open Access Journals (Sweden)

    Ruimin Wang

    2013-01-01

    Full Text Available The research on the triangle packing problem has important theoretic significance, which has broad application prospects in material processing, network resource optimization, and so forth. Generally speaking, the orientation of the triangle should be limited in advance, since the triangle packing problem is NP-hard and has continuous properties. For example, the polygon is not allowed to rotate; then, the approximate solution can be obtained by optimization method. This paper studies the triangle packing problem by a new kind of method. Such concepts as angle region, corner-occupying action, corner-occupying strategy, and edge-conjoining strategy are presented in this paper. In addition, an edge-conjoining and corner-occupying algorithm is designed, which is to obtain an approximate solution. It is demonstrated that the proposed algorithm is highly efficient, and by the time complexity analysis and the analogue experiment result is found.

  15. A heuristic method for solving triangle packing problem

    Institute of Scientific and Technical Information of China (English)

    CHEN Chuan-bo; HE Da-hua

    2005-01-01

    Given a set of triangles and a rectangle container, the triangle packing problem is to determine ifthese triangles can be placed into the container without overlapping. Triangle packing problem is a special case of polygon packing problem and also NP-hard, so it is unlikely that an efficient and exact algorithm can be developed to solve this problem. In this paper, a new concept of rigid placement is proposed, based on which a discrete solution space called rigid solution space is constructed. Each solution in the rigid solution space can be built by continuously applying legal rigid placements one by one until all the triangles are placed into the rectangle container without overlapping. The proposed Least-Destruction-First (LDF) strategy determines which rigid placement has the privilege to go into the rectangle container. Based on this, a heuristic algorithm is proposed to solve the problem.Combining Least-Destruction-First strategy with backtracking, the corresponding backtracking algorithm is proposed. Computational results show that our proposed algorithms are efficient and robust. With slight modification, these techniques can be conveniently used for solving polygon packing problem.

  16. Solving non-standard packing problems by global optimization and heuristics

    CERN Document Server

    Fasano, Giorgio

    2014-01-01

    This book results from a long-term research effort aimed at tackling complex non-standard packing issues which arise in space engineering. The main research objective is to optimize cargo loading and arrangement, in compliance with a set of stringent rules. Complicated geometrical aspects are also taken into account, in addition to balancing conditions based on attitude control specifications. Chapter 1 introduces the class of non-standard packing problems studied. Chapter 2 gives a detailed explanation of a general model for the orthogonal packing of tetris-like items in a convex domain. A number of additional conditions are looked at in depth, including the prefixed orientation of subsets of items, the presence of unusable holes, separation planes and structural elements, relative distance bounds as well as static and dynamic balancing requirements. The relative feasibility sub-problem which is a special case that does not have an optimization criterion is discussed in Chapter 3. This setting can be exploit...

  17. Two personification strategies for solving circles packing problem

    Institute of Scientific and Technical Information of China (English)

    黄文奇[1; 许如初[2

    1999-01-01

    Two personification strategies are presented, which yield a highly efficient and practical algorithm for solving one of the NP hard problems——circles packing problem on the basis of the quasi-physical algorithm. A very clever polynomial time complexity degree approximate algorithm for solving this problem has been reported by Dorit S.Hochbaum and Wolfgang Maass in J. ACM. Their algorithm is extremely thorough-going and of great theoretical significance. But, just as they pointed out, their algorithm is feasible only in conception and even for examples frequently encountered in everyday life and of small scale, it is the case more often than not that up to a million years would be needed to perform calculations with this algorithm. It is suggested toward the end of their paper that a heuristic algorithm of higher practical effectiveness should be sought out. A direct response to their suggestion is intented to provide.

  18. Performance Analysis of Selective Breeding Algorithm on One Dimensional Bin Packing Problems

    Science.gov (United States)

    Sriramya, P.; Parvathavarthini, B.

    2012-12-01

    The bin packing optimization problem packs a set of objects into a set of bins so that the amount of wasted space is minimized. The bin packing problem has many important applications. The objective is to find a feasible assignment of all weights to bins that minimizes the total number of bins used. The bin packing problem models several practical problems in such diverse areas as industrial control, computer systems, machine scheduling, VLSI chip layout and etc. Selective breeding algorithm (SBA) is an iterative procedure which borrows the ideas of artificial selection and breeding process. By simulating artificial evolution in this way SBA algorithm can easily solve complex problems. One dimensional bin packing benchmark problems are taken for evaluating the performance of the SBA. The computational results of SBA algorithm show optimal solution for the tested benchmark problems. The proposed SBA algorithm is a good problem-solving technique for one dimensional bin packing problems.

  19. Class and Home Problems: Optimization Problems

    Science.gov (United States)

    Anderson, Brian J.; Hissam, Robin S.; Shaeiwitz, Joseph A.; Turton, Richard

    2011-01-01

    Optimization problems suitable for all levels of chemical engineering students are available. These problems do not require advanced mathematical techniques, since they can be solved using typical software used by students and practitioners. The method used to solve these problems forces students to understand the trends for the different terms…

  20. A Novel Quantum Inspired Cuckoo Search Algorithm for Bin Packing Problem

    Directory of Open Access Journals (Sweden)

    Abdesslem Layeb

    2012-05-01

    Full Text Available The Bin Packing Problem (BPP is one of the most known combinatorial optimization problems. This problem consists to pack a set of items into a minimum number of bins. There are several variants of this problem; the most basic problem is the one-dimensional bin packing problem (1-BPP. In this paper, we present a new approach based on the quantum inspired cuckoo search algorithm to deal with the 1-BPP problem. The contribution consists in defining an appropriate quantum representation based on qubit representation to represent bin packing solutions. The second contribution is proposition of a new hybrid quantum measure operation which uses first fit heuristic to pack no filled objects by the standard measure operation. The obtained results are very encouraging and show the feasibility and effectiveness of the proposed approach.

  1. Nonconvex continuous models for combinatorial optimization problems with application to satisfiability and node packing problems

    NARCIS (Netherlands)

    Warners, J.P.

    1997-01-01

    We show how a large class of combinatorial optimization problems can be reformulated as a nonconvex minimization problem over the unit hyper cube with continuous variables. No additional constraints are required; all constraints are incorporated in the n onconvex objective function, which is a polyn

  2. Hybrid next-fit algorithm for the two-dimensional rectangle bin-packing problem

    NARCIS (Netherlands)

    J.B.G. Frenk (Hans); G. Galambos

    1987-01-01

    textabstractWe present a new approximation algorithm for the two-dimensional bin-packing problem. The algorithm is based on two one-dimensional bin-packing algorithms. Since the algorithm is of next-fit type it can also be used for those cases where the output is required to be on-line (e. g. if we

  3. Solving the non-oriented three-dimensional bin packing problem with stability and load bearing constraints

    DEFF Research Database (Denmark)

    Hansen, Jesper

    2003-01-01

    The three-dimensional bin packing problem is concerned with packing a given set of rectangular items into rectangular bins. We are interested in solving real-life problems where rotations of items are allowed and the packings must be packable and stable. Load bearing of items is taken into account...

  4. Packing, Scheduling and Covering Problems in a Game-Theoretic Perspective

    CERN Document Server

    Kleiman, Elena

    2011-01-01

    Many packing, scheduling and covering problems that were previously considered by computer science literature in the context of various transportation and production problems, appear also suitable for describing and modeling various fundamental aspects in networks optimization such as routing, resource allocation, congestion control, etc. Various combinatorial problems were already studied from the game theoretic standpoint, and we attempt to complement to this body of research. Specifically, we consider the bin packing problem both in the classic and parametric versions, the job scheduling problem and the machine covering problem in various machine models. We suggest new interpretations of such problems in the context of modern networks and study these problems from a game theoretic perspective by modeling them as games, and then concerning various game theoretic concepts in these games by combining tools from game theory and the traditional combinatorial optimization. In the framework of this research we in...

  5. A CLASS OF GENERALIZED MULTIPROCESSOR SCHEDULING PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    YANG Xiaoguang

    2000-01-01

    The paper discusses a class of generalized multiprocessor scheduling problems which is to arrange some independent jobs on almost identical processors. Different from the classical multiprocessor scheduling, each job may only be processed by some processors,not all. In this paper, we first prove that the problems of minimization makespan and minimization total weighted completion time can be solved by the polynomial algorithms if all processing time are unit time. Then for arbitrary processing time, we try to analyze the worst performance of list schedule (LS) method and longest processing time(LPT) method when there are only two machines involved. We show that the bounds for LS and LPT are exactly two.

  6. Model and algorithm for container ship stowage planning based on bin-packing problem

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In a general case, container ship serves many different ports on each voyage. A stowage planning for container ship made at one port must take account of the influence on subsequent ports. So the complexity of stowage planning problem increases due to its multi-ports nature. This problem is NP-hard problem. In order to reduce the computational complexity, the problem is decomposed into two sub-problems in this paper. First, container ship stowage problem (CSSP) is regarded as "packing problem", ship-bays on the board of vessel are regarded as bins, the number of slots at each bay are taken as capacities of bins, and containers with different characteristics (homogeneous containers group) are treated as items packed. At this stage, there are two objective functions, one is to minimize the number of bays packed by containers and the other is to minimize the number of overstows. Secondly, containers assigned to each bays at first stage are allocate to special slot, the objective functions are to minimize the metacentric height, heel and overstows.The taboo search heuristics algorithm are used to solve the subproblem. The main focus of this paper is on the first subproblem. A case certifies the feasibility of the model and algorithm.

  7. A branch-and-cut algorithm for the bandwidth packing problem

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.; Park, K.; Kang, S.

    1994-12-31

    We consider the bandwidth packing problem, that arises in the telecommunication network. The problem is to determine the set of calls and the assignment of them to the paths in an arc capacitated network to maximize profit. The problem is formulated by using path variables. To solve LP relaxation, an efficient column generation technique is proposed. Moreover, modified cover inequality is used to strengthen the formulation. The algorithm incorporates the column generation technique and the strong cutting plane approach into the branch-and-bound scheme. We test the proposed algorithm on several problem instances. The results show that the algorithm can be used to solve the problems to optimality within reasonably small time limits.

  8. A pure quasi-human algorithm for solving the cuboid packing problem

    Institute of Scientific and Technical Information of China (English)

    HUANG WenQi; HE Kun

    2009-01-01

    We excavate the wisdom from an old Chinese proverb "gold corner, silver side and strawy void", and further Improve it into "maximum value in diamond cave" for solving the NP-hard cuboid packing problem. We extract, Integrate and formalize the idea by west modern mathematical tools, and propose a pure quasi-human algorithm. The performance of the algorithm is evaluated on two sets of public benchmarks. For 100 strongly heterogeneous difficult benchmarks, experiments show an average packing utilization of 87.31%, which surpasses current best record reported in the literature by 1.83%. For 47 difficult benchmarks without orientation constraint, experiments show an average volume utilization of 92.05%, which improves current best record reported in the literature by 1.05%.

  9. A Modified Partially Mapped MultiCrossover Genetic Algorithm for Two-Dimensional Bin Packing Problem

    Directory of Open Access Journals (Sweden)

    M. Sarabian

    2010-01-01

    Full Text Available Problem statement: Non-oriented case of Two-Dimensional Rectangular Bin Packing Problem (2DRBPP was studied in this study. The objective of this problem was to pack a given set of small rectangles, which may be rotated by 90°, without overlaps into a minimum numbers of identical large rectangles. Our aim was to improve the performance of the MultiCrossover Genetic Algorithm (MXGA proposed from the literature for solving the problem. Approach: Four major components of the MXGA consisted of selection, crossover, mutation and replacement are considered in this study. Initial computational investigations were conducted independently on the named components using some benchmark problem instances. The new MXGA was constructed by combining the rank selection, modified Partially Mapped Crossover (PMXm, mutation with two mutation operators and elitism replacement scheme with filtration. Results: Extensive computational experiments of the new proposed algorithm, MXGA, Standard GA (SGA, Unified Tabu Search (UTS and Randomized Descent Method (RDM were performed using benchmark data sets. Conclusion: The computational results indicated that the new proposed algorithm was able to outperform MXGA, SGA, UTS and RDM.

  10. A new class of variational equation problems

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Applying an analysis method to a group of multivariable equations, a new class of variational equations are proved. This method is more concise and more direct than the others. This result can be applied to some stochastic control models.

  11. MNP:A Class of NP Optimization Problems

    Institute of Scientific and Technical Information of China (English)

    程歧; 朱洪

    1997-01-01

    A large class of NP optimization problems called MNP are studied.It is shown that Rmax(2)is in this class and some problems which are not likely in Rmax(2) are in this class.A new kind of reductions,SL-reductions,is defined to preserve approximability and nonapproximability,so it is a more general version of L-reductions and A-reductions.Then some complete problems of this class under SL-reductions are shown and it is proved that the max-clique problem is one of them.So all complete problems in this class are as difficult to approximate as the max-clique problem.

  12. An analysis of shift class design problems

    NARCIS (Netherlands)

    L.G. Kroon (Leo); A.W.J. Kolen

    1994-01-01

    textabstractIn this paper we consider a generalization of the Fixed Job Schedule Problem (FJSP) which appears in the aircraft maintenance process at an airport. A number of jobs must be carried out where each job requires processing from a fixed time to a fixed finish time. These jobs must be carrie

  13. A non-classical class of variational problems

    CERN Document Server

    Cruz, Pedro A F; Zinober, Alan S I

    2009-01-01

    We study a new non-classical class of variational problems that is motivated by some recent research on the non-linear revenue problem in the field of economics. This class of problem can be set up as a maximising problem in the Calculus of Variations (CoV) or Optimal Control. However, the state value at the final fixed time, y(T), is a priori unknown and the integrand is a function of the unknown y(T). This is a non-standard CoV problem. In this paper we apply the new costate boundary conditions p(T) in the formulation of the CoV problem. We solve some sample examples in this problem class using the numerical shooting method to solve the resulting TPBVP, and incorporate the free y(T) as an additional unknown. Essentially the same results are obtained using symbolic algebra software.

  14. Dynamic Multi-class Network Loading Problem

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The dynamic network loading problem (DNLP) consists in determining on a congested network, timedependent arc volumes, together with arc and path travel times, given the time varying path flow departure rates over a finite time horizon. The objective of this paper is to present the formulation of an analytical dynamic multiclass network loading model. The model does not require the assumption of the FIFO condition. The existence of a solution to the model is shown.

  15. SPECTRUM OF DIRECTED KIRKMAN PACKING DESIGNS

    Institute of Scientific and Technical Information of China (English)

    ZhangYan; DuBeiliang

    2003-01-01

    The problem studied in this article is the directed Kirkman packing, the resolvable directed packing which requires all blocks to be of size three except that ,each resolution class should contain either one block of size two(when v=2(mod 3)) or one block of size four (when v=l (mod 3)). A directed Kirkman packing design DKPD(v) is a resolvable directed packing of a v-set by the maximum possible number of resolution classes of this type. This article investigates the spectrum of DKPD(v) and it is found that it contains all positive integers v≥3 and v≠5,6.

  16. SUBSPACE SEARCH METHOD FOR A CLASS OF LEAST SQUARES PROBLEM

    Institute of Scientific and Technical Information of China (English)

    Zi-Luan Wei

    2000-01-01

    A subspace search method for solving a class of least squares problem is pre sented in the paper. The original problem is divided into many independent sub problems, and a search direction is obtained by solving each of the subproblems, as well as a new iterative point is determined by choosing a suitable steplength such that the value of residual norm is decreasing. The convergence result is also given. The numerical test is also shown for a special problem,

  17. A dichotomous search-based heuristic for the three-dimensional sphere packing problem

    Directory of Open Access Journals (Sweden)

    Mhand Hifi

    2015-12-01

    Full Text Available In this paper, the three-dimensional sphere packing problem is solved by using a dichotomous search-based heuristic. An instance of the problem is defined by a set of $ n $ unequal spheres and an object of fixed width and height and, unlimited length. Each sphere is characterized by its radius and the aim of the problem is to optimize the length of the object containing all spheres without overlapping. The proposed method is based upon beam search, in which three complementary phases are combined: (i a greedy selection phase which determines a series of eligible search subspace, (ii a truncated tree search, using a width-beam search, that explores some promising paths, and (iii a dichotomous search that diversifies the search. The performance of the proposed method is evaluated on benchmark instances taken from the literature where its obtained results are compared to those reached by some recent methods of the literature. The proposed method is competitive and it yields promising results.

  18. A CLASS OF STRONGLY NONLINEAR SINGULARLY PERTURBED INTERIOR LAYER PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    唐荣荣

    2004-01-01

    In this paper, a class of strongly nonlinear singularly perturbed interior layer problems are considered by the theory of differential inequalities and the corrective theory of interior layer. The existence of solution is proved and the asymptotic behavior of solution for the boundary value problems are studied. And the satisfying result is obtained.

  19. Pre-Service Class Teacher' Ability in Solving Mathematical Problems and Skills in Solving Daily Problems

    Science.gov (United States)

    Aljaberi, Nahil M.; Gheith, Eman

    2016-01-01

    This study aims to investigate the ability of pre-service class teacher at University of Petrain solving mathematical problems using Polya's Techniques, their level of problem solving skills in daily-life issues. The study also investigates the correlation between their ability to solve mathematical problems and their level of problem solving…

  20. Minimax theory for a class of nonlinear statistical inverse problems

    Science.gov (United States)

    Ray, Kolyan; Schmidt-Hieber, Johannes

    2016-06-01

    We study a class of statistical inverse problems with nonlinear pointwise operators motivated by concrete statistical applications. A two-step procedure is proposed, where the first step smoothes the data and inverts the nonlinearity. This reduces the initial nonlinear problem to a linear inverse problem with deterministic noise, which is then solved in a second step. The noise reduction step is based on wavelet thresholding and is shown to be minimax optimal (up to logarithmic factors) in a pointwise function-dependent sense. Our analysis is based on a modified notion of Hölder smoothness scales that are natural in this setting.

  1. The Monty Hall Problem as a Class Activity Using Clickers

    Science.gov (United States)

    Irons, Stephen H.

    2012-01-01

    Demonstrating probabilistic outcomes using real-time data is especially well-suited to larger lecture classes where one can generate large data sets easily. The difficulty comes in quickly collecting, analyzing, and displaying the information. With the advent of wireless polling technology (clickers), this difficulty is removed. In this paper we describe an activity developed in one of our physics classes to test one of the classic cases of probability in popular culture, The Monty Hall Problem. Using clickers, a paper handout, and stickers, one can easily probe the class opinion on the outcome and then vividly and definitively test it. At the end of the activity, the students have confronted through direct experience the often counterintuitive nature of probability.

  2. An Evaluable Theory for a Class of Migration Problems

    OpenAIRE

    G Haag; Weidlich, W.

    1983-01-01

    A master equation formulation for a class of migration problems describing the spatio-temporal dynamics of a system of regions is introduced. The transition probabilities are functions of trend parameters, which characterize preferences, growth pool and saturation effects. The trend parameters can be determined by regression analysis from the empirical migration matrix. The solution of meanvalue equations yields a nonlinear migration prognosis. The relation between trend parameters and motiva...

  3. Solving a Class of Generalized Nash Equilibrium Problems

    Institute of Scientific and Technical Information of China (English)

    Peiyu LI; Guihua LIN

    2013-01-01

    Generalized Nash equilibrium problem (GNEP) is an important model that has many applications in practice.However,a GNEP usually has multiple or even infinitely many Nash equilibrium points and it is not easy to choose a favorable solution from those equilibria.This paper considers a class of GNEP with some kind of separability.We first extend the so-called normalized equilibrium concept to the stationarity sense and then,we propose an approach to solve the normalized stationary points by reformulating the GNEP as a single optimization problem.We further demonstrate the proposed approach on a GNEP model in similar product markets.

  4. Role-playing in the problem-based learning class.

    Science.gov (United States)

    Chan, Zenobia C Y

    2012-01-01

    Learning and teaching have been conceptualized and executed in many styles, such as self-learning, peer learning, and interaction between the learner and mentor. Today, openness to alternative ideas and embracing innovative approaches in nursing education are encouraged in order to meet students' learning interests and needs, and to address ever-changing healthcare requests. Problem-based learning has been widely adopted in nursing education, with various positive effects on students' learning, such as motivated learning, team work, problem-solving skills and critical thinking. Role-plays have been demonstrated as an effective learning strategy that includes an active and experiential feature that facilitates students' autonomy in their health-related learning. However, there is a lack of discussion of whether and how role-play can be used in problem-based learning (PBL). This paper shows the development of a classroom-based innovation using role-play in the PBL class for higher diploma year-one nurse students (a total of 20 students, five per group). This paper consists of five sections: a) the literature on PBL and nurse education, and role-plays as the innovation; b) the PBL case scenario with the illustration of the two role-play scripts, c) student evaluation on role-play in the PBL class; d) discussions on both achievements and limitations of this innovation, and e) the conclusion. It is hoped that this paper will be an example to other nurse educators who are keen on exploring interactive and student-driven learning and teaching strategies in the PBL class.

  5. A class of self-similar hydrodynamics test problems

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, Scott D [Los Alamos National Laboratory; Brown, Lowell S [Los Alamos National Laboratory; Nelson, Eric M [Los Alamos National Laboratory; Alme, Marv L [Los Alamos National Laboratory

    2010-12-08

    We consider self-similar solutions to the gas dynamics equations. One such solution - a spherical geometry Gaussian density profile - has been analyzed in the existing literature, and a connection between it, a linear velocity profile, and a uniform specific internal energy profile has been identified. In this work, we assume the linear velocity profile to construct an entire class of self-similar sol utions in both cylindrical and spherical geometry, of which the Gaussian form is one possible member. After completing the derivation, we present some results in the context of a test problem for compressible flow codes.

  6. The Problems and Solutions of Learning English Effectively in class

    Institute of Scientific and Technical Information of China (English)

    钟丽君

    2016-01-01

    English, as an international language, is becoming more and more important in our society. Its proficiency has become a major requirement for attaining the highest level of professional and economic success around the world. We, English learners mainly learn English in Classroom, so classroom is regarded as the most important place where we learn English language. This paper gives out an analysis of the problems which lead to the ineffective English learning and discusses the solutions of an effective English learning in class according to the author' s own experience in English teaching in secondary schools and colleges.

  7. Polynomial approximations of a class of stochastic multiscale elasticity problems

    Science.gov (United States)

    Hoang, Viet Ha; Nguyen, Thanh Chung; Xia, Bingxing

    2016-06-01

    We consider a class of elasticity equations in {mathbb{R}^d} whose elastic moduli depend on n separated microscopic scales. The moduli are random and expressed as a linear expansion of a countable sequence of random variables which are independently and identically uniformly distributed in a compact interval. The multiscale Hellinger-Reissner mixed problem that allows for computing the stress directly and the multiscale mixed problem with a penalty term for nearly incompressible isotropic materials are considered. The stochastic problems are studied via deterministic problems that depend on a countable number of real parameters which represent the probabilistic law of the stochastic equations. We study the multiscale homogenized problems that contain all the macroscopic and microscopic information. The solutions of these multiscale homogenized problems are written as generalized polynomial chaos (gpc) expansions. We approximate these solutions by semidiscrete Galerkin approximating problems that project into the spaces of functions with only a finite number of N gpc modes. Assuming summability properties for the coefficients of the elastic moduli's expansion, we deduce bounds and summability properties for the solutions' gpc expansion coefficients. These bounds imply explicit rates of convergence in terms of N when the gpc modes used for the Galerkin approximation are chosen to correspond to the best N terms in the gpc expansion. For the mixed problem with a penalty term for nearly incompressible materials, we show that the rate of convergence for the best N term approximation is independent of the Lamé constants' ratio when it goes to {infty}. Correctors for the homogenization problem are deduced. From these we establish correctors for the solutions of the parametric multiscale problems in terms of the semidiscrete Galerkin approximations. For two-scale problems, an explicit homogenization error which is uniform with respect to the parameters is deduced. Together

  8. An Improved Heuristic Recursive Strategy Based on Genetic Algorithm for the Strip Rectangular Packing Problem%求解矩形Packing问题的基于遗传算法的启发式速归策略

    Institute of Scientific and Technical Information of China (English)

    张德福; 陈胜达; 刘艳娟

    2007-01-01

    An improved heuristic recursive strategy combining with genetic algorithm is presented in this paper. Firstly, this method searches some rectangles, which have the same length or width, to form some layers without waste space, then it uses the heuristic recur sive strategies to calculate the height of the remaining packing order and uses the evolutionary capability of genetic algorithm to reduce the height. The computational results on several classes of benchmark problems have shown that the presented algorithm can compete with known evolutionary heuristics. It performs better especially for large test problems.

  9. Stability of Solutions to Classes of Traveling Salesman Problems.

    Science.gov (United States)

    Niendorf, Moritz; Kabamba, Pierre T; Girard, Anouck R

    2016-04-01

    By performing stability analysis on an optimal tour for problems belonging to classes of the traveling salesman problem (TSP), this paper derives margins of optimality for a solution with respect to disturbances in the problem data. Specifically, we consider the asymmetric sequence-dependent TSP, where the sequence dependence is driven by the dynamics of a stack. This is a generalization of the symmetric non sequence-dependent version of the TSP. Furthermore, we also consider the symmetric sequence-dependent variant and the asymmetric non sequence-dependent variant. Amongst others these problems have applications in logistics and unmanned aircraft mission planning. Changing external conditions such as traffic or weather may alter task costs, which can render an initially optimal itinerary suboptimal. Instead of optimizing the itinerary every time task costs change, stability criteria allow for fast evaluation of whether itineraries remain optimal. This paper develops a method to compute stability regions for the best tour in a set of tours for the symmetric TSP and extends the results to the asymmetric problem as well as their sequence-dependent counterparts. As the TSP is NP-hard, heuristic methods are frequently used to solve it. The presented approach is also applicable to analyze stability regions for a tour obtained through application of the k -opt heuristic with respect to the k -neighborhood. A dimensionless criticality metric for edges is proposed, such that a high criticality of an edge indicates that the optimal tour is more susceptible to cost changes in that edge. Multiple examples demonstrate the application of the developed stability computation method as well as the edge criticality measure that facilitates an intuitive assessment of instances of the TSP.

  10. Avian photoreceptor patterns represent a disordered hyperuniform solution to a multiscale packing problem.

    Science.gov (United States)

    Jiao, Yang; Lau, Timothy; Hatzikirou, Haralampos; Meyer-Hermann, Michael; Joseph C Corbo; Torquato, Salvatore

    2014-02-01

    Optimal spatial sampling of light rigorously requires that identical photoreceptors be arranged in perfectly regular arrays in two dimensions. Examples of such perfect arrays in nature include the compound eyes of insects and the nearly crystalline photoreceptor patterns of some fish and reptiles. Birds are highly visual animals with five different cone photoreceptor subtypes, yet their photoreceptor patterns are not perfectly regular. By analyzing the chicken cone photoreceptor system consisting of five different cell types using a variety of sensitive microstructural descriptors, we find that the disordered photoreceptor patterns are "hyperuniform" (exhibiting vanishing infinite-wavelength density fluctuations), a property that had heretofore been identified in a unique subset of physical systems, but had never been observed in any living organism. Remarkably, the patterns of both the total population and the individual cell types are simultaneously hyperuniform. We term such patterns "multihyperuniform" because multiple distinct subsets of the overall point pattern are themselves hyperuniform. We have devised a unique multiscale cell packing model in two dimensions that suggests that photoreceptor types interact with both short- and long-ranged repulsive forces and that the resultant competition between the types gives rise to the aforementioned singular spatial features characterizing the system, including multihyperuniformity. These findings suggest that a disordered hyperuniform pattern may represent the most uniform sampling arrangement attainable in the avian system, given intrinsic packing constraints within the photoreceptor epithelium. In addition, they show how fundamental physical constraints can change the course of a biological optimization process. Our results suggest that multihyperuniform disordered structures have implications for the design of materials with novel physical properties and therefore may represent a fruitful area for future

  11. Avian photoreceptor patterns represent a disordered hyperuniform solution to a multiscale packing problem

    Science.gov (United States)

    Jiao, Yang; Lau, Timothy; Hatzikirou, Haralampos; Meyer-Hermann, Michael; Corbo, Joseph C.; Torquato, Salvatore

    2014-02-01

    Optimal spatial sampling of light rigorously requires that identical photoreceptors be arranged in perfectly regular arrays in two dimensions. Examples of such perfect arrays in nature include the compound eyes of insects and the nearly crystalline photoreceptor patterns of some fish and reptiles. Birds are highly visual animals with five different cone photoreceptor subtypes, yet their photoreceptor patterns are not perfectly regular. By analyzing the chicken cone photoreceptor system consisting of five different cell types using a variety of sensitive microstructural descriptors, we find that the disordered photoreceptor patterns are "hyperuniform" (exhibiting vanishing infinite-wavelength density fluctuations), a property that had heretofore been identified in a unique subset of physical systems, but had never been observed in any living organism. Remarkably, the patterns of both the total population and the individual cell types are simultaneously hyperuniform. We term such patterns "multihyperuniform" because multiple distinct subsets of the overall point pattern are themselves hyperuniform. We have devised a unique multiscale cell packing model in two dimensions that suggests that photoreceptor types interact with both short- and long-ranged repulsive forces and that the resultant competition between the types gives rise to the aforementioned singular spatial features characterizing the system, including multihyperuniformity. These findings suggest that a disordered hyperuniform pattern may represent the most uniform sampling arrangement attainable in the avian system, given intrinsic packing constraints within the photoreceptor epithelium. In addition, they show how fundamental physical constraints can change the course of a biological optimization process. Our results suggest that multihyperuniform disordered structures have implications for the design of materials with novel physical properties and therefore may represent a fruitful area for future

  12. A Personified Annealing Algorithm for Circles Packing Problem%求解圆形packing问题的拟人退火算法

    Institute of Scientific and Technical Information of China (English)

    张德富; 李新

    2005-01-01

    Circles packing problem is an NP-hard problem and is difficult to solve. In this paper, a hybrid search strategy for circles packing problem is discussed. A way of generating new configuration is presented by simulating the moving of elastic objects, which can avoid the blindness of simulated annealing search and make iteration process converge fast. Inspired by the life experiences of people,an effective personified strategy to jump out of local minima is given. Based on the simulated annealing idea and personification strategy, an effective personified annealing algorithm for circles packing problem is developed. Numerical experiments on benchmark problem instances show that the proposed algorithm outperforms the best algorithm in the literature.

  13. [The immuno-endocrine system. A new endocrine theory: the problem of the packed transport].

    Science.gov (United States)

    Csaba, György

    2011-05-15

    Since the eighties of the last century hormone content was justified in immune cells (lymphocytes, granulocytes, monocytes, macrophages and mast cells), which produce, store and secrete these hormones. Although the amount of these materials in immune cells is relatively small, the mass of the producers (immune cells) is so large, that the phenomenon must be considered from endocrinological point of view, underlying the important differences between the "classical" and immuno-endocrine systems. Cells of the classic (built-in) endocrine system are mono-producers, while immune cells can synthesize many types of hormones (polyproducers). In addition, these cells can transport the whole hormone-producing machinery to the site of need, producing a local effect. This can be observed, for example, in the case of endorphin producing immune cells during inflammation and during early pregnancy around the chorionic villi. Hormone producing immune cells also have receptors for many hormones, so that they are poly-receivers. Via hormone producing and receiving capacity there is a bidirectional connection between the neuro-endocrine and immuno-endocrine systems. In addition, there is a network inside the immuno-endocrine system. The packed transport theory attempts to explain the mechanism and importance of the immuno-endocrine system.

  14. An off-line dual maximum resource bin packing model for solving the maintenance problem in the aviation industry

    Directory of Open Access Journals (Sweden)

    George Cristian Gruia

    2013-05-01

    Full Text Available In the aviation industry, propeller motor engines have a lifecycle of several thousand hours of flight and the maintenance is an important part of their lifecycle. The present article considers a multi-resource, priority-based case scheduling problem, which is applied in a Romanian manufacturing company, that repairs and maintains helicopter and airplane engines at a certain quality level imposed by the aviation standards. Given a reduced budget constraint, the management’s goal is to maximize the utilization of their resources (financial, material, space, workers, by maintaining a prior known priority rule. An Off-Line Dual Maximum Resource Bin Packing model, based on a Mixed Integer Programming model is thus presented. The obtained results show an increase with approx. 25% of the Just in Time shipping of the engines to the customers and approx. 12,5% increase in the utilization of the working area.

  15. Emotional Psychological and Related Problems among Truant Youths: An Exploratory Latent Class Analysis

    Science.gov (United States)

    Dembo, Richard; Briones-Robinson, Rhissa; Ungaro, Rocio Aracelis; Gulledge, Laura M.; Karas, Lora M.; Winters, Ken C.; Belenko, Steven; Greenbaum, Paul E.

    2012-01-01

    Intervention Project. Results identified two classes of youths: Class 1(n=9) - youths with low levels of delinquency, mental health and substance abuse issues; and Class 2(n=37) - youths with high levels of these problems. Comparison of these two classes on their urine analysis test results and parent/guardian reports of traumatic events found…

  16. QUANTUM COMPLEXITY OF THE INTEGRATION PROBLEM FOR ANISOTROPIC CLASSES

    Institute of Scientific and Technical Information of China (English)

    Xiao-fei Hu; Pei-xin Ye

    2005-01-01

    We obtain the optimal order of high-dimensional integration complexity in the quantum computation model in anisotropic Sobolev classes Wr∞ ([0, 1]d) and Holder Nikolskii classes Hr∞([0, 1]d). It is proved that for these classes of functions there is a speed-up of quantum algorithms over deterministic classical algorithms due to factor n-1 and over randomized classical methods due to factor n-1/2. Moreover, we give an estimation for optimal query complexity in the class H∧∞ (D) whose smoothness index is the boundary of some complete set in Zd+.

  17. Rack 'em, pack 'em and stack 'em: challenges and opportunities in teaching large classes in higher education.

    Science.gov (United States)

    Kumar, Saravana

    2013-01-01

    The higher education sector is undergoing tremendous change, driven by complex driving forces including financial, administrative, and organisational and stakeholder expectations. It is in this challenging environment, educators are required to maintain and improve the quality of teaching and learning outcomes while contending with increasing class sizes. Despite mixed evidence on the effectiveness of large classes on student outcomes, large classes continue to play an important part in higher education. While large classes pose numerous challenges, they also provide opportunities for innovative solutions. This paper provides an overview of these challenges and highlights opportunities for innovative solutions. PMID:24358851

  18. Existence for a class of discrete hyperbolic problems

    Directory of Open Access Journals (Sweden)

    Luca Rodica

    2006-01-01

    Full Text Available We investigate the existence and uniqueness of solutions to a class of discrete hyperbolic systems with some nonlinear extreme conditions and initial data, in a real Hilbert space.

  19. A Class of Nonlinear Singularly Perturbed Problems for Reaction Diffusion Equations with Boundary Perturbation

    Institute of Scientific and Technical Information of China (English)

    Jia-qi Mo; Wan-tao Lin

    2006-01-01

    A class of nonlinear singularly perturbed problems for reaction diffusion equations with boundary perturbation are considered. Under suitable conditions, the asymptotic behavior of solution for the initial boundary value problems is studied using the theory of differential inequalities.

  20. Minimizers of a Class of Constrained Vectorial Variational Problems: Part I

    KAUST Repository

    Hajaiej, Hichem

    2014-04-18

    In this paper, we prove the existence of minimizers of a class of multiconstrained variational problems. We consider systems involving a nonlinearity that does not satisfy compactness, monotonicity, neither symmetry properties. Our approach hinges on the concentration-compactness approach. In the second part, we will treat orthogonal constrained problems for another class of integrands using density matrices method. © 2014 Springer Basel.

  1. Multisplitting Iteration Schemes for Solving a Class of Nonlinear Complementarity Problems

    Institute of Scientific and Technical Information of China (English)

    Chen-liang Li; Jin-ping Zeng

    2007-01-01

    We consider several synchronous and asynchronous multisplitting iteration schemes for solving a class of nonlinear complementarity problems with the system matrix being an H-matrix. We establish the convergence theorems for the schemes. The numerical experiments show that the schemes are efficient for solving the class of nonlinear complementarity problems.

  2. SPECTRUM OF DIRECTED KIRKMAN PACKING DESIGNS%有向Kirkman填充设计的谱

    Institute of Scientific and Technical Information of China (English)

    张彦; 杜北梁

    2003-01-01

    The problem studied in this article is the directed Kirkman packing,the resolvable directed packing which requires all blocks to be of size three except that,each resolution class should contain either one block of size two(when v≡2(mod 3)) or one block of size four (when v≡1 (mod 3)). A directed Kirkman packing design DKPD(v) is a resolvable directed packing of a v-set by the maximum possible number of resolution classes of this type. This article investigates the spectrum of DKPD(v) and it is found that it contains all positive integers v≥3 and v≠ 5,6.

  3. On a class of inverse electrostatic and elasticity problems

    OpenAIRE

    Artemev, Andrei; Parnovski, Leonid; Polterovich, Iosif

    2012-01-01

    We study the inverse electrostatic and elasticity problems associated with Poisson and Navier equations. The uniqueness of solutions of these problems is proved for piecewise constant electric charge and internal stress distributions having a checkered structure: they are constant on rectangular blocks. Such distributions appear naturally in practical applications. We also discuss computational challenges arising in the numerical implementation of our method.

  4. On stochastic approximation algorithms for classes of PAC learning problems

    Energy Technology Data Exchange (ETDEWEB)

    Rao, N.S.V.; Uppuluri, V.R.R.; Oblow, E.M.

    1994-03-01

    The classical stochastic approximation methods are shown to yield algorithms to solve several formulations of the PAC learning problem defined on the domain [o,1]{sup d}. Under some assumptions on different ability of the probability measure functions, simple algorithms to solve some PAC learning problems are proposed based on networks of non-polynomial units (e.g. artificial neural networks). Conditions on the sizes of these samples required to ensure the error bounds are derived using martingale inequalities.

  5. An object oriented C++ class library for solving electromagnetic time domain problems

    International Nuclear Information System (INIS)

    The author has developed a C++ class library to solve three dimensional electromagnetic transient problems. All the data and method for solving field are defined as classes and users can build their specific application using these classes of the library. In the first part of this paper, the algorithms and class structure of the library are described. Three application examples are shown in the rest part. Showing these examples the ease of merging with the advanced computer environment and the enhancability of the library to a specific problem are shown

  6. An object oriented C++ class library for solving electromagnetic time domain problems

    International Nuclear Information System (INIS)

    The author has developed a C++ class library to solve three dimensional electromagnetic transient problems. All the data and method for solving field are defined as classes and users can build their specific application using these classes of the library. In the first part of this paper, the algorithms and class structure of the library are described. Three application examples are shown in the rest part. Showing these examples the ease of merging with the advanced computer environment and the enhancability of the library to a specific problem are shown. copyright 1997 American Institute of Physics

  7. Renormalization problem in a class of nonrenormalizable theories

    International Nuclear Information System (INIS)

    A possible way to approach the simplest nonrenormalizable theory - phi4 theory in more than four space-time dimensions - is described. The problems of extension to other nonrenormalizable theories are discussed and the conclusions reached so far are compared with the corresponding ones for renormalizable theories. For more details, Comm. Math. Phys. or DESY 75/12 should be consulted. (BJ)

  8. Optimized packings with applications

    CERN Document Server

    Pintér, János

    2015-01-01

    This volume presents a selection of case studies that address a substantial range of optimized object packings (OOP) and their applications. The contributing authors are well-recognized researchers and practitioners. The mathematical modelling and numerical solution aspects of each application case study are presented in sufficient detail. A broad range of OOP problems are discussed: these include various specific and non-standard container loading and object packing problems, as well as the stowing of hazardous and other materials on container ships, data centre resource management, automotive engineering design, space station logistic support, cutting and packing problems with placement constraints, the optimal design of LED street lighting, robust sensor deployment strategies, spatial scheduling problems, and graph coloring models and metaheuristics for packing applications. Novel points of view related to model development and to computational nonlinear, global, mixed integer optimization and heuristic st...

  9. An active learning based classification strategy for the minority class problem: application to histopathology annotation

    Directory of Open Access Journals (Sweden)

    Doyle Scott

    2011-10-01

    Full Text Available Abstract Background Supervised classifiers for digital pathology can improve the ability of physicians to detect and diagnose diseases such as cancer. Generating training data for classifiers is problematic, since only domain experts (e.g. pathologists can correctly label ground truth data. Additionally, digital pathology datasets suffer from the "minority class problem", an issue where the number of exemplars from the non-target class outnumber target class exemplars which can bias the classifier and reduce accuracy. In this paper, we develop a training strategy combining active learning (AL with class-balancing. AL identifies unlabeled samples that are "informative" (i.e. likely to increase classifier performance for annotation, avoiding non-informative samples. This yields high accuracy with a smaller training set size compared with random learning (RL. Previous AL methods have not explicitly accounted for the minority class problem in biomedical images. Pre-specifying a target class ratio mitigates the problem of training bias. Finally, we develop a mathematical model to predict the number of annotations (cost required to achieve balanced training classes. In addition to predicting training cost, the model reveals the theoretical properties of AL in the context of the minority class problem. Results Using this class-balanced AL training strategy (CBAL, we build a classifier to distinguish cancer from non-cancer regions on digitized prostate histopathology. Our dataset consists of 12,000 image regions sampled from 100 biopsies (58 prostate cancer patients. We compare CBAL against: (1 unbalanced AL (UBAL, which uses AL but ignores class ratio; (2 class-balanced RL (CBRL, which uses RL with a specific class ratio; and (3 unbalanced RL (UBRL. The CBAL-trained classifier yields 2% greater accuracy and 3% higher area under the receiver operating characteristic curve (AUC than alternatively-trained classifiers. Our cost model accurately predicts

  10. A Class of Singularly Perturbed Problems for Nonlinear Two-Species Competitive Reaction-Diffusion System

    Institute of Scientific and Technical Information of China (English)

    Wang Geng

    2006-01-01

    A class of nonlinear two-species competitive singularly perturbed initial-boundary-value problems for reaction-diffusion systems are studied. Under suitable assumptions, by using the stretched variable, the formal asymptotic expansion for the problems is constructed. The uniform validity of the solution for initial-boundary-value problems is obtained by using the theory of differential inequalities.

  11. A CLASS OF NONLINEAR SINGULARLY PERTURBED PROBLEMS FOR REACTION DIFFUSION EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    莫嘉琪

    2003-01-01

    A class of nonlinear singularly perturbed problems for reaction diffusion equations are considered.Under suitable conditions,by using the theory of differential inequalities,the asymptotic behavior of solutions for the initial boundary value problems are studied,reduced problems of which possess two intersecting solutions.

  12. A CLASS OF SINGULARLY PERTURBED INITIAL BOUNDARY PROBLEM FOR REACTION DIFFUSION EQUATION

    Institute of Scientific and Technical Information of China (English)

    Xie Feng

    2003-01-01

    The singularly perturbed initial boundary value problem for a class of reaction diffusion equation isconsidered. Under appropriate conditions, the existence-uniqueness and the asymptotic behavior of the solu-tion are showed by using the fixed-point theorem.

  13. Limit Cycles of a Class of Hilbert's Sixteenth Problem Presented by Fractional Differential Equations

    Directory of Open Access Journals (Sweden)

    Zangeneh HRZ

    2010-01-01

    Full Text Available The second part of Hilbert's sixteenth problem concerned with the existence and number of the limit cycles for planer polynomial differential equations of degree n. In this article after a brief review on previous studies of a particular class of Hilbert's sixteenth problem, we will discuss the existence and the stability of limit cycles of this class in the form of fractional differential equations.

  14. 条形装箱问题的优化模型和增广Lagrange算法%An Optimization Model for the Strip-packing Problem and Its Augmented Lagrangian Method

    Institute of Scientific and Technical Information of China (English)

    于洪霞; 张宏伟; 张立卫

    2006-01-01

    This paper formulates a two-dimensional strip packing problem as a nonlinear programming (NLP) problem and establishes the first-order optimality conditions for the NLP problem. A numerical algorithm for solving this NLP problem is given to find exact solutions to strip-packing problems involving up to 10 items.Approximate solutions can be found for big-sized problems by decomposing the set of items into small-sized blocks of which each block adopts the proposed numerical algorithm. Numerical results show that the approximate solutions to big-sized problems obtained by this method are superior to those by NFDH, FFDH and BFDH approaches.

  15. Lossless Convexification of Control Constraints for a Class of Nonlinear Optimal Control Problems

    Science.gov (United States)

    Blackmore, Lars; Acikmese, Behcet; Carson, John M.,III

    2012-01-01

    In this paper we consider a class of optimal control problems that have continuous-time nonlinear dynamics and nonconvex control constraints. We propose a convex relaxation of the nonconvex control constraints, and prove that the optimal solution to the relaxed problem is the globally optimal solution to the original problem with nonconvex control constraints. This lossless convexification enables a computationally simpler problem to be solved instead of the original problem. We demonstrate the approach in simulation with a planetary soft landing problem involving a nonlinear gravity field.

  16. Optimal Packed String Matching

    DEFF Research Database (Denmark)

    Ben-Kiki, Oren; Bille, Philip; Breslauer, Dany;

    2011-01-01

    In the packed string matching problem, each machine word accommodates – characters, thus an n-character text occupies n/– memory words. We extend the Crochemore-Perrin constantspace O(n)-time string matching algorithm to run in optimal O(n/–) time and even in real-time, achieving a factor – speedup...... over traditional algorithms that examine each character individually. Our solution can be efficiently implemented, unlike prior theoretical packed string matching work. We adapt the standard RAM model and only use its AC0 instructions (i.e., no multiplication) plus two specialized AC0 packed string...

  17. An Analysis on the Problem of Students’ Engagement in English Class

    Institute of Scientific and Technical Information of China (English)

    陈瑜

    2015-01-01

    Students’ engagement in English class is a common problem facing by English teachers.This study analyzes the factors which influence students’ classroom engagement, tries to find out possible solutions to solve this problem from the perspective of SLA theory and teaching approaches and gives implications for future teaching.

  18. Solutions for a Class of Singular Nonlinear Boundary Value Problem Involving Critical Exponent

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, we consider the existence of multiple solutions for a class of singular nonlinear boundary value problem involving critical exponent in Weighted Sobolev Spaces. The existence of two solutions is established by using the Ekeland Variational Principle. Meanwhile, the uniqueness of positive solution for the same problem is also obtained under different assumptions.

  19. POSITIVE SOLUTION TO A CLASS OF SINGULAR FRACTIONAL BOUNDARY VALUE PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In this paper,we investigate the existence and uniqueness of positive solutions to a class of singular fractional boundary value problem.The existence of positive solutions to the problem is based on a fixed point theorem in partially ordered sets.

  20. Dynamic and stochastic planning problems with online decision making : a novel class of models

    NARCIS (Netherlands)

    Cremers, M.L.A.G.

    2009-01-01

    In this thesis we study planning problems in the area of routing and scheduling by means of mathematical models and (numerical) optimization. Characteristic for this class of problems is that here-and-now decisions have to be made while only probabilistic information is available on the relevant pla

  1. ADOPTING THE PROBLEM BASED LEARNING APPROACH IN A GIS PROJECT MANAGEMENT CLASS

    Science.gov (United States)

    Problem Based Learning (PBL) is a process that emphasizes the need for developing problem solving skills through hands-on project formulation and management. A class adopting the PBL method provides students with an environment to acquire necessary knowledge to encounter, unders...

  2. Free boundary value problems for a class of generalized diffusion equation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The transport behavior of free boundary value problems for a class of generalized diffusion equations was studied. Suitable similarity transformations were used to convert the problems into a class of singular nonlinear two-point boundary value problems and similarity solutions were numerical presented for different representations of heat conduction function, convection function, heat flux function, and power law parameters by utilizing the shooting technique. The results revealed the flux transfer mechanism and the character as well as the effects of parameters on the solutions.

  3. Epistemological effects of a problem solving approach in nonquantitative introductory science classes

    Science.gov (United States)

    McCoy, Bradley

    2011-04-01

    General studies science classes at many universities, such as physical science, earth science, or astronomy, stress memorization and repetition of concepts. This approach leaves students with little appreciation for how science is used to explain phenomena from general principles. We present a novel instructional technique for an earth science class in which the students are instructed in the use of a general problem solving strategy, adapted from well-known quantitative problem solving strategies, in order to train the students in how to apply physical principles. Using the Epistemological Beliefs Assessment for Physical Science, we have found that explicit training in problem solving significantly improves students' epistemology.

  4. Some Problems and Solutions of Applying TBLT in a Chinese Large-sized Class

    Institute of Scientific and Technical Information of China (English)

    周尧

    2014-01-01

    This paper mainly looks into the problems of applying Task-based Language Teaching(TBLT) and possible solutions to them.TBLT is now also widely used in Chinese classrooms.It can also be called as "the Age of Task"(Johnson,2001: P.194).However,there are still some problems when TBLT is applied in China.Most of the problems are caused by the large class size and examination-oriented education in China.

  5. Prediction-correction alternating direction method for a class of constrained rain-max problems

    Institute of Scientific and Technical Information of China (English)

    LI Min; HE Bingsheng

    2007-01-01

    The problems concerned in this paper are a class of constrained min-max problems. By introducing the Lagrange multipliers to the linearconstraints, such problems can be solved by some projection type prediction-correction methods. However, to obtain components of the predictor one by one, we use an alternating direction method. And then the new iterate is generated by a minor correction. Global convergence of the proposed method is proved. Finally, numerical results for a constrained single-facility location problem are provided to verify that the new method is effective for some practical problems.

  6. Packing Products: Polystyrene vs. Cornstarch

    Science.gov (United States)

    Starr, Suzanne

    2009-01-01

    Packing materials such as polystyrene take thousands of years to decompose, whereas packing peanuts made from cornstarch, which some companies are now using, can serve the same purpose, but dissolve in water. The author illustrates this point to her class one rainy day using the sculptures students made from polystyrene and with the cornstarch…

  7. Problems that Class Teachers Faced in the Classroom Related to Undesired Behaviors and Their Solutions

    Directory of Open Access Journals (Sweden)

    Barış ÇETİN

    2013-04-01

    Full Text Available The aim this study is to determine the undesired behaviors of students that class teachers faced in the classroom and their solutions. The sample of the study consists of 37 class teachers working in the provinces of Gumushane, Canakkale, Erzurum, Istanbul, Tekirdag, Kocaeli, Kutahya, Bursa, Samsun, Eskisehir, and Mus in Turkey in the fall term of 2011-2012 academic year. As a result, the undesired behaviors of students that teachers faced in the classroom have been determined as not obeying the class rules, swearing, talking without permission, shyness, hyperactivity and lack of attention, and problems caused by watching violent TV programs (such as threatening. Solutions to these problems have been stated as: punishments and awards, warning, ignoring, behaving more sincerely towards students, including students by means of activities, guidance service, giving assignment, making students sit in front of the class, and playing games.

  8. Effect of Problem Based Learning Scenario on Knowledge of Third Class Students About Childhood Poisoning

    OpenAIRE

    Nazan Karaoğlu; Sevgi Pekcan; Burak Cem Soner; Muzaffer Şeker; Rahmi Örs

    2011-01-01

    Introduction: It is stated that students cannot carry their knowledge on basic medical sciences that they gained with classical education to clinical classes and clinical practice and problem based learning (PBL) can compensate this drawback. It was aimed to evaluate the effect of PBL scenario written on this topic on level of knowledge about childhood poisoning of third class students who completed the most of theoretical pharmacology education.Materials and Method: A questionnaire form prep...

  9. A CLASS OF NONLINEAR NONLOCAL SINGULARLY PERTURBED PROBLEMS FOR REACTION DIFFUSION EQUATIONS WITH BOUNDARY PERTURBATION

    Institute of Scientific and Technical Information of China (English)

    MO Jia-qi; WANG Hui; LIN Wan-tao

    2005-01-01

    A class of nonlinear nonlocal for singularly perturbed Robin initial boundary value problems for reaction diffusion equations with boundary perturbation is considered. Under suitable conditions, first, the outer solution of the original problem was obtained. Secondly, using the stretched variable, the composing expansion method and the expanding theory of power series the initial layer was constructed. Finally, using the theory of differential inequalities the asymptotic behavior of solution for the initial boundary value problems was studied, and educing some relational inequalities the existence and uniqueness of solution for the original problem and the uniformly valid asymptotic estimation were discussed.

  10. A recurrent neural network for solving a class of generalized convex optimization problems.

    Science.gov (United States)

    Hosseini, Alireza; Wang, Jun; Hosseini, S Mohammad

    2013-08-01

    In this paper, we propose a penalty-based recurrent neural network for solving a class of constrained optimization problems with generalized convex objective functions. The model has a simple structure described by using a differential inclusion. It is also applicable for any nonsmooth optimization problem with affine equality and convex inequality constraints, provided that the objective function is regular and pseudoconvex on feasible region of the problem. It is proven herein that the state vector of the proposed neural network globally converges to and stays thereafter in the feasible region in finite time, and converges to the optimal solution set of the problem.

  11. A rectangle bin packing optimization approach to the signal scheduling problem in the FlexRay static segment

    Institute of Scientific and Technical Information of China (English)

    Rui ZHAO; Gui-he QIN; Jia-qiao LIU

    2016-01-01

    As FlexRay communication protocol is extensively used in distributed real-time applications on vehicles, signal scheduling in FlexRay network becomes a critical issue to ensure the safe and efficient operation of time-critical applications. In this study, we propose a rectangle bin packing optimization approach to schedule communication signals with timing constraints into the FlexRay static segment at minimum bandwidth cost. The proposed approach, which is based on integer linear program-ming (ILP), supports both the slot assignment mechanisms provided by the latest version of the FlexRay specification, namely, the single sender slot multiplexing, and multiple sender slot multiplexing mechanisms. Extensive experiments on a synthetic and an automotive X-by-wire system case study demonstrate that the proposed approach has a well optimized performance.

  12. A first passage problem and its applications to the analysis of a class of stochastic models

    Directory of Open Access Journals (Sweden)

    Lev Abolnikov

    1992-01-01

    Full Text Available A problem of the first passage of a cumulative random process with generally distributed discrete or continuous increments over a fixed level is considered in the article as an essential part of the analysis of a class of stochastic models (bulk queueing systems, inventory control and dam models.

  13. Initial-boundary value problems for a class of nonlinear thermoelastic plate equations

    Institute of Scientific and Technical Information of China (English)

    Zhang Jian-Wen; Rong Xiao-Liang; Wu Run-Heng

    2009-01-01

    This paper studies initial-boundary value problems for a class of nonlinear thermoelastic plate equations. Under some certain initial data and boundary conditions,it obtains an existence and uniqueness theorem of global weak solutions of the nonlinear thermoelstic plate equations,by means of the Galerkin method. Moreover,it also proves the existence of strong and classical solutions.

  14. On a class of non-self-adjoint periodic boundary value problems with discrete real spectrum

    OpenAIRE

    Boulton, Lyonell; Levitin, Michael; Marletta, Marco

    2010-01-01

    In [arXiv:0801.0172] we examined a family of periodic Sturm-Liouville problems with boundary and interior singularities which are highly non-self-adjoint but have only real eigenvalues. We now establish Schatten class properties of the associated resolvent operator.

  15. SHIFT OF SHOCK POSITION FOR A CLASS OF NONLINEAR SINGULARLY PERTURBED PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    莫嘉琪; 王辉

    2005-01-01

    The shift of shock position for a class of nonlinear singularly perturbed problems is considered using a special and simple method. The location of the shock wave will be larger moved, even from interior layer to the boundary layer when the boundary conditions change smaller.

  16. Hydrostatic Pressure Project: Linked-Class Problem-Based Learning in Engineering

    Science.gov (United States)

    Davis, Freddie J.; Lockwood-Cooke, Pamela; Hunt, Emily M.

    2011-01-01

    Over the last few years, WTAMU Mathematics, Engineering and Science faculty has used interdisciplinary projects as the basis for implementation of a linked-class approach to Problem-Based Learning (PBL). A project that has significant relevance to engineering statics, fluid mechanics, and calculus is the Hydrostatic Pressure Project. This project…

  17. A Comparison of Traditional Teaching Methods and Problem-Based Learning in an Addiction Studies Class.

    Science.gov (United States)

    Sevening, Diane; Baron, Mark

    2002-01-01

    Study compared students' achievement gains and attitudes using traditional (lecture-based) teaching methods and problem-based learning (PBL) techniques in an addiction studies class. Results showed students did not respond well to PBL and preferred a lecture-based format. Pretest mean scores indicated the PBL group entered the course at a higher…

  18. SOLVING A CLASS OF INVERSE QP PROBLEMS BY A SMOOTHING NEWTON METHOD

    Institute of Scientific and Technical Information of China (English)

    Xiantao Xiao; Liwei Zhang

    2009-01-01

    We consider an inverse quadratic programming (IQP) problem in which the parameters in the objective function of a given quadratic programming (QP) problem are adjusted as little as possible so that a known feasible solution becomes the optimal one. This problem can be formulated as a minimization problem with a positive semidefinite cone constraint and its dual (denoted IQD(A, b)) is a semismoothly differentiable (SC~1) convex program-ming problem with fewer variables than the original one. In this paper a smoothing New-ton method is used for getting a Karush-Kuhn-Tucker point of IQD(A, b). The proposed method needs to solve only one linear system per iteration and achieves quadratic conver-gence. Numerical experiments are reported to show that the smoothing Newton method is effective for solving this class of inverse quadratic programming problems.

  19. Asymptotic solution for a class of weakly nonlinear singularly perturbed reaction diffusion problem

    Institute of Scientific and Technical Information of China (English)

    TANG Rong-rong

    2009-01-01

    Under appropriate conditions, with the perturbation method and the theory of differential inequalities, a class of weakly nonlinear singularly perturbed reaction diffusion problem is considered. The existence of solution of the original problem is proved by constructing the auxiliary functions. The uniformly valid asymptotic expansions of the solution for arbitrary mth order approximation are obtained through constructing the formal solutions of the original problem, expanding the nonlinear terms to the power in small parameter e and comparing the coefficient for the same powers of ε. Finally, an example is provided, resulting in the error of O(ε2).

  20. Formulation space search approach for the teacher/class timetabling problem

    Directory of Open Access Journals (Sweden)

    Kochetov Yuri

    2008-01-01

    Full Text Available We consider the well known NP-hard teacher/class timetabling problem. Variable neighborhood search and tabu search heuristics are developed based on idea of the Formulation Space Search approach. Two types of solution representation are used in the heuristics. For each representation we consider two families of neighborhoods. The first family uses swapping of time periods for teacher (class timetable. The second family bases on the idea of large Kernighan-Lin neighborhoods. Computation results for difficult random test instances show high efficiency of the proposed approach. .

  1. Hybrid Method for a Class of Stochastic Bi-criteria Optimization Problems

    Directory of Open Access Journals (Sweden)

    Wan Zhong

    2010-01-01

    Full Text Available We study a class of stochastic bi-criteria optimization problems with one quadratic and one linear objective functions and some linear inequality constraints. A hybrid method of chance-constrained programming (CCP combined with variance expectation (VE is proposed to find the optimal solution of the original problem. By introducing the expectation level, the bi-criteria problem is converted into a single-objective problem. By introducing the confidence level and the preference level of decision maker, we obtain a relaxed robust deterministic formulation of the stochastic problem. Then, an interactive algorithm is developed to solve the obtained deterministic model with three parameters, reflecting the preferences of decision maker. Numerical experiments show that the proposed method is superior to the existing methods. The optimal solution obtained by our method has less violation of the constraints and reflects the satisfaction degree of decision-maker.

  2. Power Packing

    Centers for Disease Control (CDC) Podcasts

    2011-08-16

    In this podcast for kids, the Kidtastics talk about how to pack a lunch safely, to help keep you from getting sick.  Created: 8/16/2011 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/16/2011.

  3. Packing Smart

    Centers for Disease Control (CDC) Podcasts

    2011-08-22

    In this podcast for kids, the Kidtastics talk about packing a lunch that's not boring and is full of the power and energy kids need to make it through the day.  Created: 8/22/2011 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/22/2011.

  4. A CLASS OF NONLINEAR SINGULARLY PERTURBED INITIAL BOUNDARY VALUE PROBLEMS FOR REACTION DIFFUSION EQUATIONS WITH BOUNDARY PERTURBATION

    Institute of Scientific and Technical Information of China (English)

    Mo Jiaqi

    2007-01-01

    A class of nonlinear initial boundary value problems for reaction diffusion equations with boundary perturbation is considered. Under suitable conditions and using the theory of differential inequalities the asymptotic solution of the initial boundary value problems is studied.

  5. Scaffolded problem-solving, learning approaches and understanding of concepts in an introductory college physics class

    Science.gov (United States)

    Haack, Constance

    This study was an exploration of students' use of scaffolded problems as part of their homework in an introductory calculus-based physics class. The study included consideration of the possible relationship of students' meaningful and rote learning approaches. The sample was comprised of 48 students who had completed all study instruments. Of this number, 23 did homework assignments that included scaffolded problems that had been divided into multiple steps that simplify, highlight, and organize the knowledge associated with the problem solving process. The other 25 students did non-scaffolded homework assignments. The Mechanics Baseline Test, given at the beginning of the study, measured students' prior knowledge of physics concepts. The Learning Approach Questionnaire, also given at the beginning of the study, measured students' meaningful and rote approaches to learning. Student responses to 6 qualitative physics problems and their selection of concepts associated with 4 quantitative physics problems was a gauge of their understanding of physics concepts. These 10 problems were distributed between 2 classroom examinations given during the study. At the end of the study 4 students who had done scaffolded homework problems and 4 students who had done non-scaffolded homework problems participated in think aloud protocols. They verbalized their thoughts as they attempted to solve 2 physics problems. Characterizations of individual problem solving approaches emerged from the think aloud protocols. An analysis of statistical data showed that students who did scaffolded problems attained significantly greater understanding of physics concepts than students who did non-scaffolded assignments. There were no significant differences by learning approaches, and no significant interactions. This indicates that scaffolded homework problems may benefit students regardless of learning orientation. Think aloud protocols revealed patterns of difference between students who had

  6. L1-norm packings from function fields

    Institute of Scientific and Technical Information of China (English)

    LI; Hongli

    2005-01-01

    In this paper, we study some packings in a cube, namely, how to pack n points in a cube so as to maximize the minimal distance. The distance is induced by the L1-norm which is analogous to the Hamming distance in coding theory. Two constructions with reasonable parameters are obtained, by using some results from a function field including divisor class group, narrow ray class group, and so on. We also present some asymptotic results of the two packings.

  7. A new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We show that there exists a new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem. In such a solution, the infinitesimal body is confined to the vicinity of a primary and moves on a nearly circular orbit. This orbit is almost perpendicular to the orbital plane of the primaries, where the line of symmetry of the orbit lies. The existence is shown by applying a corollary of Arenstorf’s fixed point theorem to a periodicity equation system of the problem. And this existence doesn’t require any restriction on the mass ratio of the primaries, nor on the eccentricity of their relative elliptic orbit. Potential relevance of this new class of periodic solutions to real celestial body systems and the follow-up studies in this respect are also discussed.

  8. A new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem

    Institute of Scientific and Technical Information of China (English)

    XU XingBo; FU YanNing

    2009-01-01

    We show that there exists a new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem.In such a solution,the infinitesimal body is confined to the vicinity of a primary and moves on a nearly circular orbit.This orbit is almost perpendicular to the orbital plane of the pri-maries,where the line of symmetry of the orbit lies.The existence is shown by applying a corollary of Arenstorf's fixed point theorem to s periodicity equation system of the problem.And this existence doesn't require any restriction on the mass ratio of the primaries,nor on the eccentricity of their rela-tive elliptic orbit.Potential relevance of this new class of periodic solutions to real celestial body sys-tems and the follow-up studies in this respect are also discussed.

  9. A New Class of Complementarity Function and the Boundedness of Its Merit Function for Symmetric Cone Complementarity Problem

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yun-sheng

    2014-01-01

    In this paper, we introduce a new class of two-parametric penalized function, which includes the penalized minimum function and the penalized Fischer-Burmeister func-tion over symmetric cone complementarity problems. We propose that this class of function is a class of complementarity functions(C-function). Moreover, its merit function has bounded level set under a weak condition.

  10. Solving the Linear Programming Relaxation of Cutting and Packing Problems: A Hybrid Simplex Method/Subgradient Optimization Procedure

    OpenAIRE

    Degraeve, Zeger; Peeters, Marc

    2000-01-01

    In this paper we present a new method for solving the linear programming relaxation of the Cutting Stock Problem. The method is based on the relationship between column generation and Lagrange relaxation. We have called our method the Hybrid Simplex Method/Subgradient Optimization Procedure. We test our procedure on generated data sets and compare it with the classical column generation approach.

  11. Optimality and second order duality for a class of quasi-differentiable multiobjective optimization problem

    Directory of Open Access Journals (Sweden)

    Sahay Rishi R.

    2013-01-01

    Full Text Available A second order Mond-Weir type dual is presented for a non-differentiable multiobjective optimization problem with square root terms in the objective as well as in the constraints. Optimality and duality results are presented. Classes of generalized higher order η - bonvex and related functions are introduced to study the optimality and duality results. A fractional case is presented at the end.

  12. A New Global Optimization Algorithm for Solving a Class of Nonconvex Programming Problems

    Directory of Open Access Journals (Sweden)

    Xue-Gang Zhou

    2014-01-01

    Full Text Available A new two-part parametric linearization technique is proposed globally to a class of nonconvex programming problems (NPP. Firstly, a two-part parametric linearization method is adopted to construct the underestimator of objective and constraint functions, by utilizing a transformation and a parametric linear upper bounding function (LUBF and a linear lower bounding function (LLBF of a natural logarithm function and an exponential function with e as the base, respectively. Then, a sequence of relaxation lower linear programming problems, which are embedded in a branch-and-bound algorithm, are derived in an initial nonconvex programming problem. The proposed algorithm is converged to global optimal solution by means of a subsequent solution to a series of linear programming problems. Finally, some examples are given to illustrate the feasibility of the presented algorithm.

  13. Symmetry Reduction and Cauchy Problems for a Class of Fourth-Order Evolution Equations

    Institute of Scientific and Technical Information of China (English)

    LI Ji-Na; ZHANG Shun-Li

    2008-01-01

    We exploit higher-order conditional symmetry to reduce initial-value problems for evolution equations to Cauehy problems for systems of ordinary differential equations (ODEs).We classify a class of fourth-order evolution equations which admit certain higher-order generalized conditional symmetries (GCSs) and give some examples to show the main reduction procedure.These reductions cannot be derived within the framework of the standard Lie approach,which hints that the technique presented here is something essential for the dimensional reduction of evolution equations.

  14. Improving classification of mature microRNA by solving class imbalance problem

    Science.gov (United States)

    Wang, Ying; Li, Xiaoye; Tao, Bairui

    2016-05-01

    MicroRNAs (miRNAs) are ~20–25 nucleotides non-coding RNAs, which regulated gene expression in the post-transcriptional level. The accurate rate of identifying the start sit of mature miRNA from a given pre-miRNA remains lower. It is noting that the mature miRNA prediction is a class-imbalanced problem which also leads to the unsatisfactory performance of these methods. We improved the prediction accuracy of classifier using balanced datasets and presented MatFind which is used for identifying 5‧ mature miRNAs candidates from their pre-miRNA based on ensemble SVM classifiers with idea of adaboost. Firstly, the balanced-dataset was extract based on K-nearest neighbor algorithm. Secondly, the multiple SVM classifiers were trained in orderly using the balance datasets base on represented features. At last, all SVM classifiers were combined together to form the ensemble classifier. Our results on independent testing dataset show that the proposed method is more efficient than one without treating class imbalance problem. Moreover, MatFind achieves much higher classification accuracy than other three approaches. The ensemble SVM classifiers and balanced-datasets can solve the class-imbalanced problem, as well as improve performance of classifier for mature miRNA identification. MatFind is an accurate and fast method for 5‧ mature miRNA identification.

  15. Strongly polynomial algorithm for a class of minimum-cost flow problems with separable convex objectives

    CERN Document Server

    Vegh, Laszlo A

    2011-01-01

    A well-studied nonlinear extension of the minimum-cost flow problem is to minimize the objective \\sum_{ij\\in E} C_{ij}(f_{ij}) over feasible flows f, where on each arc ij of the network, C_{ij} is a convex function. We give a strongly polynomial algorithm for finding an exact optimal solution for a broad class of such problems. The key characteristic of this class is that an optimal solution can be computed exactly provided its support. The class includes convex quadratic objectives and also certain market equilibria problems, such as Fisher's market with linear or with spending constraint utilities. Thereby we give the first strongly polynomial algorithms for separable quadratic minimum-cost flows and for Fisher's market with spending constraint utilities, settling open questions posed e.g. in [Hochbaum,94] and in [Vazirani,10], respectively. The running time is O(m^4\\log m) for quadratic costs, O(n^2(m+n\\log n)\\log n+n^4) for Fisher's markets with linear utilities and O(m^2(m+n\\log n)\\log m+m(n^3+m)) for sp...

  16. Improving classification of mature microRNA by solving class imbalance problem.

    Science.gov (United States)

    Wang, Ying; Li, Xiaoye; Tao, Bairui

    2016-01-01

    MicroRNAs (miRNAs) are ~20-25 nucleotides non-coding RNAs, which regulated gene expression in the post-transcriptional level. The accurate rate of identifying the start sit of mature miRNA from a given pre-miRNA remains lower. It is noting that the mature miRNA prediction is a class-imbalanced problem which also leads to the unsatisfactory performance of these methods. We improved the prediction accuracy of classifier using balanced datasets and presented MatFind which is used for identifying 5' mature miRNAs candidates from their pre-miRNA based on ensemble SVM classifiers with idea of adaboost. Firstly, the balanced-dataset was extract based on K-nearest neighbor algorithm. Secondly, the multiple SVM classifiers were trained in orderly using the balance datasets base on represented features. At last, all SVM classifiers were combined together to form the ensemble classifier. Our results on independent testing dataset show that the proposed method is more efficient than one without treating class imbalance problem. Moreover, MatFind achieves much higher classification accuracy than other three approaches. The ensemble SVM classifiers and balanced-datasets can solve the class-imbalanced problem, as well as improve performance of classifier for mature miRNA identification. MatFind is an accurate and fast method for 5' mature miRNA identification. PMID:27181057

  17. Enhancing Higher Order Thinking Skills In A Marine Biology Class Through Problem-Based Learning

    Directory of Open Access Journals (Sweden)

    Richard M. Magsino

    2014-10-01

    Full Text Available The purpose of this research was to examine students' perspectives of their learning in marine biology in the collaborative group context of Problem-based Learning (PBL. Students’ higher order thinking skills (HOTS using PBL involves the development of their logical thinking and reasoning abilities which stimulates their curiosity and associative thinking. This study aimed to investigate how critical thinking skills, particularly analysis, synthesis and evaluation were enhanced in a marine biology class through PBL. Qualitative research approach was used to examine student responses in a questionnaire involving 10 open-ended questions that target students’ HOTS on a problem presented in a marine biology class for BS Biology students. Using axial coding as a qualitative data analysis technique by which grounded theory can be performed, the study was able to determine how students manifest their higher reasoning abilities when confronted with a marine biology situation. Results show student responses yielding affirmative remarks on the 10 questions intended to know their level of analysis (e.g., analyzing, classifying, inferring, discriminating and relating or connecting, synthesis (e.g., synthesizing and collaborating, and evaluation (e.g., comparing, criticizing, and convincing of information from the presented marine biology problem. Consequently, students were able to effectively design experiments to address the presented issue through problem-based learning. Results of the study show that PBL is an efficient instructional strategy embedded within a conventional curriculum used to develop or enhance critical thinking in marine biology.

  18. Class attendance and cardiology examination performance: a study in problem-based medical curriculum

    OpenAIRE

    Bamuhair SS; Al Farhan AI; Althubaiti A; ur Rahman S; Al-Kadri HM

    2016-01-01

    Samira S Bamuhair,1 Ali I Al Farhan,1,2 Alaa Althubaiti,1 Saeed ur Rahman,1,2 Hanan M Al-Kadri1,3 1College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, 2Department of Family Medicine and Primary Health Care, 3Department of Obstetrics and Gynecology, King Abdulaziz Medical City, Riyadh, Saudi Arabia Background and aims: Information on the effect of students' class attendance on examination performance in a problem-based learning medical curriculum is limited. T...

  19. A Class of Singular Control Problems and the Smooth Fit Principle

    OpenAIRE

    Guo, Xin; Tomecek, Pascal

    2007-01-01

    This paper analyzes a class of singular control problems for which value functions are not necessarily smooth. Necessary and su±cient conditions for the well-known smooth ¯t principle, along with the regularity of the value functions, are given. Explicit solutions for the optimal policy and for the value functions are provided. In particular, when payo® functions satisfy the usual Inada conditions, the boundaries between action and no-action regions are smooth and strictly monotonic as postul...

  20. Optimality conditions and duality for a class of nondifferentiable multiobjective generalized fractional programming problems

    Institute of Scientific and Technical Information of China (English)

    GAO Ying; RONG Wei-dong

    2008-01-01

    This paper studies a class of multiobjective generalized fractional programming problems, where the numerators of objective functions are the sum of differentiable function and convex function, while the denominators are the difference of differentiable function and convex function. Under the assumption of Calmness Constraint Qualification the Kuhn-Tucker type necessary conditions for efficient solution are given, and the Kuhn-Tucker type sufficient conditions for efficient solution are presented under the assumptions of (F, α, ρ, d)-V-convexity.Subsequently, the optimality conditions for two kinds of duality models are formulated and duality theorems are proved.

  1. A multiplicity result for a class of quasilinear elliptic and parabolic problems

    Directory of Open Access Journals (Sweden)

    M. R. Grossinho

    1997-04-01

    Full Text Available We prove the existence of infinitely many solutions for a class of quasilinear elliptic and parabolic equations, subject respectively to Dirichlet and Dirichlet-periodic boundary conditions. We assume that the primitive of the nonlinearity at the right-hand side oscillates at infinity. The proof is based on the construction of upper and lower solutions, which are obtained as solutions of suitable comparison equations. This method allows the introduction of conditions on the potential for the study of parabolic problems, as well as to treat simultaneously the singular and the degenerate case.

  2. Research on the Optimal Parallel Algorithms of Broadcast—Class Problems

    Institute of Scientific and Technical Information of China (English)

    李晓峰; 寿标; 等

    1998-01-01

    Speedup is considered as the criterion of determining whether a parallel algorithm is optimal.But broadcast-class problems,existing only on parallel computer system,have no sequential algorithms at all.Speedup standard becomes invalid here.Through this research on broadcast algorithms under several typical prallel computation models,a model-independent evaluation standard min C2 is developed,which can be not only used to determine an optimal broadcasting algorithm,but also normalized to apply to any parallel algorithm.As a new idea,min C2 will lead to a new way in this field.

  3. Rack ‘em, pack 'em and stack ‘em: challenges and opportunities in teaching large classes in higher education

    OpenAIRE

    Saravana Kumar

    2013-01-01

    The higher education sector is undergoing tremendous change, driven by complex driving forces including financial, administrative, and organisational and stakeholder expectations. It is in this challenging environment, educators are required to maintain and improve the quality of teaching and learning outcomes while contending with increasing class sizes. Despite mixed evidence on the effectiveness of large classes on student outcomes, large classes continue to play an important part in highe...

  4. A class of singular Ro-matrices and extensions to semidefinite linear complementarity problems

    Directory of Open Access Journals (Sweden)

    Sivakumar K.C.

    2013-01-01

    Full Text Available For ARnxn and qRn, the linear complementarity problem LCP(A, q is to determine if there is xRn such that x ≥ 0; y = Ax + q ≥ 0 and xT y = 0. Such an x is called a solution of LCP(A,q. A is called an Ro-matrix if LCP(A,0 has zero as the only solution. In this article, the class of R0-matrices is extended to include typically singular matrices, by requiring in addition that the solution x above belongs to a subspace of Rn. This idea is then extended to semidefinite linear complementarity problems, where a characterization is presented for the multplicative transformation.

  5. Reflective discourse techniques: From in-class discussions to out-of-classroom problem solving

    Science.gov (United States)

    Wampler, Wendi; Demaree, Dedra; Gilbert, Dennis

    2013-01-01

    Instructors often give prompts that encourage students to articulate their beliefs and conceptions, as well as encourage students to understand the thoughts of their peers. This reflective discourse is used in a calculus-based introductory physics class at Lane Community College, where the instructor explicitly has discourse goals integrated into his course structure. We investigate whether students utilize this discourse when solving problems outside of the classroom context. We interviewed groups of students after the end of spring term, 2012. The students were asked to solve open-ended problems, with analysis focused on whether students applied this reflective discourse. Students were asked a series of follow-up questions to reflect upon their experiences in the course.

  6. A Selective Dynamic Sampling Back-Propagation Approach for Handling the Two-Class Imbalance Problem

    Directory of Open Access Journals (Sweden)

    Roberto Alejo

    2016-07-01

    Full Text Available In this work, we developed a Selective Dynamic Sampling Approach (SDSA to deal with the class imbalance problem. It is based on the idea of using only the most appropriate samples during the neural network training stage. The “average samples”are the best to train the neural network, they are neither hard, nor easy to learn, and they could improve the classifier performance. The experimental results show that the proposed method is a successful method to deal with the two-class imbalance problem. It is very competitive with respect to well-known over-sampling approaches and dynamic sampling approaches, even often outperforming the under-sampling and standard back-propagation methods. SDSA is a very simple method for automatically selecting the most appropriate samples (average samples during the training of the back-propagation, and it is very efficient. In the training stage, SDSA uses significantly fewer samples than the popular over-sampling approaches and even than the standard back-propagation trained with the original dataset.

  7. An Efficient Cost-Sensitive Feature Selection Using Chaos Genetic Algorithm for Class Imbalance Problem

    Directory of Open Access Journals (Sweden)

    Jing Bian

    2016-01-01

    Full Text Available In the era of big data, feature selection is an essential process in machine learning. Although the class imbalance problem has recently attracted a great deal of attention, little effort has been undertaken to develop feature selection techniques. In addition, most applications involving feature selection focus on classification accuracy but not cost, although costs are important. To cope with imbalance problems, we developed a cost-sensitive feature selection algorithm that adds the cost-based evaluation function of a filter feature selection using a chaos genetic algorithm, referred to as CSFSG. The evaluation function considers both feature-acquiring costs (test costs and misclassification costs in the field of network security, thereby weakening the influence of many instances from the majority of classes in large-scale datasets. The CSFSG algorithm reduces the total cost of feature selection and trades off both factors. The behavior of the CSFSG algorithm is tested on a large-scale dataset of network security, using two kinds of classifiers: C4.5 and k-nearest neighbor (KNN. The results of the experimental research show that the approach is efficient and able to effectively improve classification accuracy and to decrease classification time. In addition, the results of our method are more promising than the results of other cost-sensitive feature selection algorithms.

  8. Infeasible-interior-point algorithm for a class of nonmonotone complementarity problems and its computational complexity

    Institute of Scientific and Technical Information of China (English)

    HE; Shanglu

    2001-01-01

    [1]Andersen, E. D., Ye, Y., On homogeneous algorithm for the monotone complementarity problem, Mathematical Programming, 1999, 84(2): 375.[2]Wright, S., Ralph, D., A supperlinear infeasible-interior-point algorithm for monotone complementarity problems, Mathematics of Operations Research, 1996, 24(4): 815.[3]Kojima, M., Noma, T., Yoshise, A., Global convergence in infeasible-interior-point algorithms, Mathematical Programming, 1994, 65(1): 43.[4]Kojima, M., Megiddo, N., Noma, T., A new continuation method for complementarity problems with uniform p-functions, Mathematical Programming, 1989, 43(1): 107.[5]Kojima, M., Megiddo, N., Mizuno, S., A general framework of continuation method for complementarity problems, Mathematics of Operations Research, 1993, 18(4): 945.[6]More, J., Rheinboldt, W., On P- and S-functions and related classes of n-dimensional nonlinear mappings, Linear Algebra and Its Applications, 1973, 6(1): 45.

  9. Existence of Minimizers of a class of multi-constrained variationnal problems in the absence of compactness, symmetry and monotonicity

    CERN Document Server

    Hajaiej, Hichem

    2011-01-01

    We prove the existence of minimizers of a class of multi-constrained variational problems in which the non linearity involved does not sat- isfy compactness, monotonicity, neither symmetry properties.

  10. Class attendance and cardiology examination performance: a study in problem-based medical curriculum

    Directory of Open Access Journals (Sweden)

    Bamuhair SS

    2016-02-01

    Full Text Available Samira S Bamuhair,1 Ali I Al Farhan,1,2 Alaa Althubaiti,1 Saeed ur Rahman,1,2 Hanan M Al-Kadri1,3 1College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, 2Department of Family Medicine and Primary Health Care, 3Department of Obstetrics and Gynecology, King Abdulaziz Medical City, Riyadh, Saudi Arabia Background and aims: Information on the effect of students' class attendance on examination performance in a problem-based learning medical curriculum is limited. This study investigates the impact of different educational activities on students' academic performance in a problem-based learning curriculum. Methods: This is a retrospective cohort study conducted on the cardiology block at the College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia. All students who undertook the cardiology block during the academic year 2011–2012 were included. The students' attendance was measured using their overall attendance percentage. This percentage is a product of their attendance of many activities throughout the block. The students' performance was assessed by the final mark obtained, which is a product of many assessment elements. Statistical correlation between students' attendance and performance was established. Results: A total of 127 students were included. The average lecture attendance rate for the medical students in this study was found to be 86%. A significant positive correlation was noted between the overall attendance and the accumulated students' block mark (r=0.52; P<0.001. Students' attendance to different education activities was correlated to their final mark. Lecture attendance was the most significant predictor (P<0.001, that is, 1.0% increase in lecture attendance has predicted a 0.27 increase in students' final block mark. Conclusion: Class attendance has a positive effect on students' academic performance with stronger effect for lecture attendance compared to

  11. The pursuit of perfect packing

    CERN Document Server

    Weaire, Denis

    2008-01-01

    Coauthored by one of the creators of the most efficient space packing solution, the Weaire-Phelan structure, The Pursuit of Perfect Packing, Second Edition explores a problem of importance in physics, mathematics, chemistry, biology, and engineering: the packing of structures. Maintaining its mathematical core, this edition continues and revises some of the stories from its predecessor while adding several new examples and applications. The book focuses on both scientific and everyday problems ranging from atoms to honeycombs. It describes packing models, such as the Kepler conjecture, Voronoï decomposition, and Delaunay decomposition, as well as actual structure models, such as the Kelvin cell and the Weaire-Phelan structure. The authors discuss numerous historical aspects and provide biographical details on influential contributors to the field, including emails from Thomas Hales and Ken Brakke. With examples from physics, crystallography, engineering, and biology, this accessible and whimsical bo...

  12. 求解0-1背包问题的二进制狼群算法%A binary wolf pack algorithm for solving 0-1 knapsack problem

    Institute of Scientific and Technical Information of China (English)

    吴虎胜; 张凤鸣; 战仁军; 汪送; 张超

    2014-01-01

    狼群算法(wolf pack algorithm,WPA)源于狼群在捕食及其猎物分配中所体现的群体智能,已被成功应用于复杂函数求解。在此基础上,通过定义运动算子,对人工狼位置、步长和智能行为重新进行二进制编码设计,提出了一种解决离散空间组合优化问题的二进制狼群算法(binary wolf pack algorithm,BWPA)。该算法保留了狼群算法基于职责分工的协作式搜索特性,选取离散空间的经典问题---0-1背包问题进行仿真实验,具体通过10组经典的背包问题算例和 BWPA 算法与经典的二进制粒子群算法、贪婪遗传算法、量子遗传算法在求解3组高维背包问题时的对比计算,例证了算法具有相对更好的稳定性和全局寻优能力。%The wolf pack algorithm (WPA),inspired by swarm intelligence of wolf pack in their prey hun-ting behaviors and distribution mode,has been proposed and successfully applied in complex function optimiza-tion problems.Based on the designing of the move operator,the artificial wolves’position,step-length and in-telligent behaviors are redesigned by binary coding,and a binary wolf pack algorithm (BWPA)is proposed to solve combinatorial optimization problems in discrete spaces.BWPA preserves the feature of cooperative search-ing based on job distribution of the wolf pack and is applied to 10 classic 0-1 knapsack problems.Moreover,the 3 high-dimensional 0-1 knapsack problems are tested.All results show that BWPA has better global convergence and computational robustness and outperforms the binary particle swarm optimization algorithm,the greedy genetic al-gorithm and the quantum genetic algorithm,especially for high-dimensional knapsack problems.

  13. The pursuit of perfect packing

    CERN Document Server

    Weaire, Denis

    2000-01-01

    In 1998 Thomas Hales dramatically announced the solution of a problem that has long teased eminent mathematicians: what is the densest possible arrangement of identical spheres? The Pursuit of Perfect Packing recounts the story of this problem and many others that have to do with packing things together. The examples are taken from mathematics, physics, biology, and engineering, including the arrangement of soap bubbles in foam, atoms in a crystal, the architecture of the bee''s honeycomb, and the structure of the Giant''s Causeway. Using an informal style and with key references, the book also includes brief accounts of the lives of many of the scientists who devoted themselves to problems of packing over many centuries, together with wry comments on their efforts. It is an entertaining introduction to the field for both specialists and the more general public.

  14. Treatment engagement in adolescents with severe psychiatric problems: a latent class analysis.

    Science.gov (United States)

    Roedelof, A J M; Bongers, Ilja L; van Nieuwenhuizen, Chijs

    2013-08-01

    Motivation is considered a pivotal factor in treatment, but a better understanding of this topic is needed. Drieschner et al. (Clin Psychol Rev 23:1115-1137, 2004) proposed to distinguish treatment motivation and treatment engagement. This study aimed to discover whether it is possible to identify classes of adolescents with severe psychiatric problems having comparable profiles of treatment engagement. To this end, professionals filled out the Treatment Engagement Rating Scale 5 times for 49 adolescents (mean age 18.3 years; SD = 1.6) during the first year of case management treatment. Using a longitudinal latent class analysis, the number of profiles of treatment engagement was investigated and described. Results identified three profiles: high (19 clients, 39%), medium (20 clients, 41%) and low (10 clients, 20%). Adolescents with a high engagement profile were at first equally, and later on more engaged in treatment than clients with a medium engagement profile. Adolescents with a low engagement profile made the least effort to engage, except after 30 weeks. Adolescents with a low engagement profile were often substance-dependent males with the lowest scores on the Global Assessment of Functioning Scale after a year. Only adolescents with a high engagement profile improved on global functioning. In conclusion, it is possible to identify different treatment engagement profiles by asking one question about level of global treatment engagement. Frequent assessment of engagement of the individual client as well as including a behavioural component into assessment and treatment may help to improve case management treatment for adolescents with medium and low engagement profiles.

  15. Packing ellipsoids with overlap

    CERN Document Server

    Uhler, Caroline

    2012-01-01

    The problem of packing ellipsoids of different sizes and shapes into an ellipsoidal container so as to minimize a measure of overlap between ellipsoids is considered. A bilevel optimization formulation is given, together with an algorithm for the general case and a simpler algorithm for the special case in which all ellipsoids are in fact spheres. Convergence results are proved and computational experience is described and illustrated. The motivating application - chromosome organization in the human cell nucleus - is discussed briefly, and some illustrative results are presented.

  16. ExactPack Documentation

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, Jr., Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Israel, Daniel M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Doebling, Scott William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Woods, Charles Nathan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kaul, Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Walter, Jr., John William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rogers, Michael Lloyd [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-09

    For code verification, one compares the code output against known exact solutions. There are many standard test problems used in this capacity, such as the Noh and Sedov problems. ExactPack is a utility that integrates many of these exact solution codes into a common API (application program interface), and can be used as a stand-alone code or as a python package. ExactPack consists of python driver scripts that access a library of exact solutions written in Fortran or Python. The spatial profiles of the relevant physical quantities, such as the density, fluid velocity, sound speed, or internal energy, are returned at a time specified by the user. The solution profiles can be viewed and examined by a command line interface or a graphical user interface, and a number of analysis tools and unit tests are also provided. We have documented the physics of each problem in the solution library, and provided complete documentation on how to extend the library to include additional exact solutions. ExactPack’s code architecture makes it easy to extend the solution-code library to include additional exact solutions in a robust, reliable, and maintainable manner.

  17. Accuracy and cut-off point selection in three-class classification problems using a generalization of the Youden index.

    Science.gov (United States)

    Nakas, Christos T; Alonzo, Todd A; Yiannoutsos, Constantin T

    2010-12-10

    We study properties of the index J(3), defined as the accuracy, or the maximum correct classification, for a given three-class classification problem. Specifically, using J(3) one can assess the discrimination between the three distributions and obtain an optimal pair of cut-off points c(1)sum of the correct classification proportions will be maximized. It also serves as the generalization of the Youden index in three-class problems. Parametric and non-parametric approaches for estimation and testing are considered and methods are applied to data from an MRS study on human immunodeficiency virus (HIV) patients.

  18. Effect of Problem Based Learning Scenario on Knowledge of Third Class Students About Childhood Poisoning

    Directory of Open Access Journals (Sweden)

    Nazan Karaoğlu

    2011-08-01

    Full Text Available Introduction: It is stated that students cannot carry their knowledge on basic medical sciences that they gained with classical education to clinical classes and clinical practice and problem based learning (PBL can compensate this drawback. It was aimed to evaluate the effect of PBL scenario written on this topic on level of knowledge about childhood poisoning of third class students who completed the most of theoretical pharmacology education.Materials and Method: A questionnaire form prepared by researchers was applied to randomly chosen PBL groups without writing names and on the basis of voluntariness before and after a case of childhood poisoning which was applied as the second PBL scenario in the second midterm of 2009-2010 academic years. Numbers, percentages, chi-square and student’s t-test were used for evaluation of the questionnaire form comprised of demographic data, open-closed ended questions for measuring attitudes and level of knowledge against case of poisoning and statements as making a priority ranking.Results: In the study group, 89 students took part in pre-test and 96 students took part in post-test. In the answers to the list including the substances that are the most common causes of admission according to data of Refik Saydam National Poison Center (e.g. lotion, bath foam, cosmetics, water color and calamine lotions, the substances that the students stated to be toxic in pre-test were answered correctly in the post-test (p<0.05. Number of correct answers increased significantly for knowledge about commonly used drugs in clinical practice like anti-depressants, calcium canal blockers, oral antidiabetics that were marked as non-toxic by the students although they are toxic (p<0.05. While mean knowledge score for these 40 items was 17.52±5.82 in pre-test, it increased to 27.89±8.79 in post-test (p<0.001.Conclusion: Results of this study indicate that PBL scenario applied to the students who learned pharmacology

  19. SOLUTION WITH SHOCK-BOUNDARY LAYER AND SHOCK-INTERIOR LAYER TO A CLASS OF NONLINEAR PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In this paper,the shock behaviors of solution to a class of nonlinear singularly perturbed problems are considered.Under some appropriate conditions,the outer and interior solutions to the original problem are constructed.Using the special limit and matching theory,the expressions of solutions with the shock behavior near the boundary and some interior points are given and the domain for boundary values is obtained.

  20. Polarizable protein packing

    KAUST Repository

    Ng, Albert H.

    2011-01-24

    To incorporate protein polarization effects within a protein combinatorial optimization framework, we decompose the polarizable force field AMOEBA into low order terms. Including terms up to the third-order provides a fair approximation to the full energy while maintaining tractability. We represent the polarizable packing problem for protein G as a hypergraph and solve for optimal rotamers with the FASTER combinatorial optimization algorithm. These approximate energy models can be improved to high accuracy [root mean square deviation (rmsd) < 1 kJ mol -1] via ridge regression. The resulting trained approximations are used to efficiently identify new, low-energy solutions. The approach is general and should allow combinatorial optimization of other many-body problems. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011 Copyright © 2011 Wiley Periodicals, Inc.

  1. PROBLEM PROFILES OF AT-RISK YOUTH IN TWO SERVICE PROGRAMS: A MULTI-GROUP, EXPLORATORY LATENT CLASS ANALYSIS.

    Science.gov (United States)

    Dembo, Richard; Briones-Robinson, Rhissa; Ungaro, Rocio; Karas, Lora; Gulledge, Laura; Greenbaum, Paul E; Schmeidler, James; Winters, Ken C; Belenko, Steven

    2011-10-01

    Baseline data collected in two brief intervention projects (BI-Court and Truancy Project) were used to assess similarities and differences in subgroups of at-risk youth. Classifications of these subgroups were based on their psychosocial characteristics (e.g., substance use). Multi-group latent class analysis (LCA) identified two BI-Court subgroups of youth, and three Truant subgroups. These classes can be viewed as differing along two dimensions, substance use involvement and emotional/behavioral issues. Equality tests of means across the latent classes for BI-Court and Truancy Project youths found significant differences that were consistent with their problem group classification. These findings highlight the importance of quality assessments and allocating appropriate services based on problem profiles of at-risk youth. PMID:21966055

  2. POSITIVE SOLUTIONS TO A CLASS OF SECOND-ORDER SINGULAR SEMIPOSITIVE NEUMANN BOUNDARY VALUE PROBLEM WITH GENERAL FORM

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    By constructing an explicit Green function and using the fixed point index theory on a cone, we present some existence results of positive solutions to a class of second-order singular semipositive Neumann boundary value problem, where the nonlinear term is allowed to be nonnegative and unbounded.

  3. Challenges of Conducting Problem-Based Learning in a Large Class: A Study at Shantou University Medical College in China

    Science.gov (United States)

    Long, Ting; Qin, Danian

    2014-01-01

    One major challenge of developing problem-based learning (PBL) curricula in medical schools in China is to meet the requirements of sufficient qualified PBL tutors. Since 2011, we have developed a modified group teaching approach where an experienced faculty tutor facilitates several small PBL student groups in a large class. Although our study…

  4. Psychosocial Functioning Problems over Time among High-Risk Youths: A Latent Class Transition Analysis

    Science.gov (United States)

    Dembo, Richard; Wareham, Jennifer; Poythress, Norman; Meyers, Kathleen; Schmeidler, James

    2008-01-01

    The authors report the results of latent class analyses and latent class transition analyses of antisocial behavior risk factors among 137 youths participating in a juvenile diversion program. The study examined the youths' latent classifications using baseline and 1-year follow-up measures of family, peer, education, and mental health risk…

  5. "Hoffman v. Monsanto": Courts, Class Actions, and Perceptions of the Problem of GM Drift

    Science.gov (United States)

    McLeod-Kilmurray, Heather

    2007-01-01

    "Hoffman v. Monsanto" raises questions about the civil litigation system. Are courts appropriate institutions, and are class actions the appropriate procedure, for resolving disputes about genetically modified organisms (GMOs)? After addressing the institutional question, this article focuses on procedure. Although class actions are designed to…

  6. Poly-cross-linked PEI through aromatically conjugated imine linkages as a new class of pH-responsive nucleic acids packing cationic polymers

    Directory of Open Access Journals (Sweden)

    Shun eChen

    2016-02-01

    Full Text Available Cationic polyimines polymerized through aromatically conjugated bis-imine linkages and intra-molecular cross-linking were found to be a new class of effective transfection materials for their flexibility in structural optimization, responsiveness to intracellular environment, the ability to facilitate endosome escape and cytosol release of the nucleic acids, as well as self-metabolism. When three phthalaldehydes of different substitution positions were used to polymerize highly branched low molecular weight polyethylenimine (PEI-1.8K, the product through ortho-phthalimines (named PPOP showed significantly higher transfection activity than its two tere- and iso-analogues (named PPTP and PPIP. Physicochemical characterization confirmed the similarity of three polyimines in pH-responded degradability, buffer capacity, as well as the size and Zeta potential of the polyplexes formed from the polymers. A mechanistic speculation may be that the ortho-positioned bis-imine linkage of PPOP may only lead to the straight trans-configuration due to steric hindrance, resulting in larger loops of intra-polymer cross-linking and more flexible backbone.

  7. Maximum principles for a class of nonlinear second-order elliptic boundary value problems in divergence form

    Directory of Open Access Journals (Sweden)

    Cristian Enache

    2006-06-01

    Full Text Available For a class of nonlinear elliptic boundary value problems in divergence form, we construct some general elliptic inequalities for appropriate combinations of u(x and |∇u|2, where u(x are the solutions of our problems. From these inequalities, we derive, using Hopf's maximum principles, some maximum principles for the appropriate combinations of u(x and |∇u|2, and we list a few examples of problems to which these maximum principles may be applied.

  8. Priority classes and weighted constrained equal awards rules for the claims problem

    DEFF Research Database (Denmark)

    Szwagrzak, Karol

    2015-01-01

    . They are priority-augmented versions of the standard weighted constrained equal awards rules, also known as weighted gains methods (Moulin, 2000): individuals are sorted into priority classes; the resource is distributed among the individuals in the first priority class using a weighted constrained equal awards...... rule; if some of the resource is left over, then it is distributed among the individuals in the second priority class, again using a weighted constrained equal awards rule; the distribution carries on in this way until the resource is exhausted. Our characterization extends to a generalized version...

  9. The advantages of hydraulic packing extraction

    International Nuclear Information System (INIS)

    Today's competitive environment, coupled with industry's desire to improve the efficiency of plant maintenance and operations, has management continually seeking ways to save time, money, and, at nuclear plants, radiation exposure. One area where a tremendous improvement in efficiency can be realized is valve packing removal. For example, industry experience indicates that up to 70% of the time it takes to repack a valve can be spent just removing the old packing. In some case, the bonnets of small valves are removed to facilitate packing removal and prevent stem and stuffing box damage that can occur when using packing removal picks. In other cases, small valves are simply removed and discarded because it costs less to replace the valves than to remove the packing using conventional methods. Hydraulic packing extraction greatly reduces packing removal time and will not damage the stem nor stuffing box, thus eliminating the need for bonnet removal or valve replacement. This paper will review some of the more common problems associated with manual packing extraction techniques. It will explain how hydraulic packing extraction eliminates or greatly reduces the impact of each of the problem areas. A discussion will be provided of some actual industry operating experiences related to success stories using hydraulic packing extraction. The paper will also briefly describe the operating parameters associated with hydraulic packing extraction tools. Throughout the paper, actual operating experiences from the nuclear power, fossil power, petrochemical, and refinery industries will be used to support the conclusion that hydraulic packing extraction is an alternative that can save time, money, and exposure

  10. Right-angled Artin groups and a generalized isomorphism problem for finitely generated subgroups of mapping class groups

    CERN Document Server

    Koberda, Thomas

    2010-01-01

    Consider the mapping class group $\\Mod_{g,n}$ of a surface of finite type and a finite collection $F$ of mapping classes. In this paper we prove that there are positive exponents such that after replacing the elements of $F$ by the corresponding powers, they generate a right-angled Artin group. Under some further suitable hypotheses, these mapping classes are the vertex generators of the underlying graph, or form a right-angled Artin system in the terminology which we shall develop. We prove an analogous result for a finite volume real and complex hyperbolic $n$-manifolds, thus establishing the primary result as a rank one type phenomenon for the mapping class group. We also show the unsolvability of the isomorphism problem for finitely generated subgroups of $\\Mod_{g,n}$, and prove a homological rigidity result for right-angled Artin groups which implies a solution to the isomorphism problem for right-angled Artin groups. We thus solve a generalized isomorphism problem for finitely generated subgroups of $\\M...

  11. Study of the stability of solutions of some classes of initial boundary value problems of aerohydroelasticity

    International Nuclear Information System (INIS)

    The stability of several classes of constructions containing elastic elements has been studied. A nonlinear mathematical model of a vibration equipment device intended for the intensification of technological processes, for example, the stirring process, has been considered as an example

  12. Class and Home Problems. The Lambert W Function in Ultrafiltration and Diafiltration

    Science.gov (United States)

    Foley, Greg

    2016-01-01

    Novel analytical solutions based on the Lambert W function for two problems in ultrafiltration and diafiltration are described. Example problems, suitable for incorporation into an introductory module in unit operations, membrane processing, or numerical methods are provided in each case.

  13. A CLASS OF NONLOCAL SINGULARLY PERTURBED PROBLEMS FOR NONLINEAR HYPERBOLIC DIFFERENTIAL EQUATION

    Institute of Scientific and Technical Information of China (English)

    莫嘉琪

    2001-01-01

    The nonlocal singularly perturbed problems for the hyperbolic differential equation are considered. Under suitable conditions, using the fixed point theorem, the asymptotic behavior of solution for the initial boundary value problems is studied.

  14. Exploring Improved Artificial Bee Colony Algorithm for Solving Circle Packing Problem with Equilibrium Constraints%求解带平衡约束圆形packing问题的改进人工蜂群算法

    Institute of Scientific and Technical Information of China (English)

    王鹏; 黄帅; 朱舟全

    2014-01-01

    As is well-known, it is difficult to solve a circle packing problem with equilibrium constraints. Therefore we aim to find a new algorithm that can further enhance search capability, efficiency and success rate. To solve the circle packing problem, we propose an improved artificial bee colony ( IABC) algorithm by introducing the trend extrapolation and a fine-tuning operator into the artificial bee colony so as to reduce its randomness in the search process and improve its search efficiency. The IABC algorithm uses different adaptability degrees of food sources at different places to produce the direction of trend extrapolation and direct the search, thus reducing its randomness. To verify the effectiveness of the IABC algorithm, we apply it to solving the circle packing problem with equilibrium constraints and simulate it with the MATLAB software. The simulation results, given in Figs. 4, 5 and 6 and Tables 3 and 4, and their analysis show preliminarily that our IABC algorithm has better search capability and efficiency than both the genetic algorithm and the particle swarm optimization ( PSO) algorithm. The IABC algorithm can find optimal solutions quickly without taking much computing time, indicating its efficiency in solving a circle packing problem with equilibrium constraints.%圆形packing问题是一个著名的NP难题,求解该问题具有很高的理论与实用价值。首先将趋势外推原理和微调算子引入人工蜂群算法,对其搜索的随机性进行有效的引导优化,然后将改进后的人工蜂群算法应用于带平衡约束的圆形布局的参数优化,并在文后采用3个典型实例进行了数值实验。结果表明新算法解决带平衡约束的圆形packing问题具有较强的寻优能力和较高的寻优效率,是一种实用的方法。

  15. The Structure of Experience Acquired While Learning to Solve a Class of Problems.

    Science.gov (United States)

    Egan, Dennis Edmund

    In this study three issues related to "expert" problem solving were studied; the problems considered were based on Tower of Hanoi puzzles. A computer simulation was proposed and tested, effects of cues on subjects' performance were studied, and inter-problem transfer was analyzed. Four predictions were posed for the simulation study. Two of these…

  16. A Class of Single Machine Scheduling Problems with Variable Processing Time

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, single machine scheduling problems with variableprocessing time are raised. The criterions of the problem considered are minimizing scheduling length of all jobs, flow time and number of tardy jobs and so on. The complexity of the problem is determined.

  17. On the coupled NBEM and FEM for a class of nonlinear exterior Dirichlet problem in R2

    Institute of Scientific and Technical Information of China (English)

    WU; Zhengpeng; KANG; Tong; YU; Dehao

    2004-01-01

    In this paper, based on the natural boundary reduction advanced by Feng and Yu, we couple the finite elementapproach with the natural boundary element method to study theweak solvability and Galerkin approximation of a class ofnonlinear exterior boundary value problems. The analysis is mainlybased on the variational formulation with constraints.We provethe error estimate of the finite element solution and obtain theasymptotic rate of convergence. Finally, we also give anumerical example.

  18. Solving Two-Dimensional Rectangular Boards Packing and Stacking Problems with Discrete Differential Evolution Algorithm%二维板材组包排样问题的离散差分进化算法求解

    Institute of Scientific and Technical Information of China (English)

    姚芳; 罗家祥; 胡跃明

    2012-01-01

    为了提高包装箱的空间利用率,提出一种基于离散差分进化算法的方法,以求解二维板材组包排样问题.采用带符号的序列代表一个排样方案,提出了基于最低水平线的空隙可再利用启发式算法,对单个包的子序列进行解码,获得对单包的排样子问题的自动排样方案,使板材充分填充产生的空隙;为了改进排样结果,提出邻近策略以进一步提高空间利用率.实验结果表明,对仿真实验数据,该算法获得了比遗传算法更好的结果;对实际生产数据,该算法所得结果比原有排样方案的空间利用率更高.%To improve space utilization of packages, a new approach based on discrete differential evolution algorithm is proposed to solve the two-dimensional rectangular board packing and stacking problem. In the algorithm, a signed sequence is used to denote a solution to the problem and in order to make the best use of gaps, a new lowest horizontal line-gap reuse heuristic is proposed to decode the sub-sequence for a single package, which results in a packing solution to the sub-problem for this package. In order to improve the packing results, an adjacent strategy is also proposed to improve the overall space utilization of each solution. The experimental results show that the algorithm performs better than genetic algorithms when tested by the simulation data and it obtains better space utilization than that of the original packing solutions when tested by the real production data.

  19. Does Post Septoplasty Nasal Packing Reduce Complications?

    Directory of Open Access Journals (Sweden)

    Bijan Naghibzadeh

    2011-01-01

    Full Text Available The main issues in nasal surgery are to stabilize the nose in the good position after surgery and preserve the cartilages and bones in the favorable situation and reduce the risk of deviation recurrence. Also it is necessary to avoid the synechia formation, nasal valve narrowing, hematoma and bleeding. Due to the above mentioned problems and in order to solve and minimize them nasal packing, nasal splint and nasal mold have been advised. Patients for whom the nasal packing used may faced to some problems like naso-pulmonary reflex, intractable pain, sleep disorder, post operation infection and very dangerous complication like toxic shock syndrome. We have two groups of patients and three surgeons (one of the surgeons used post operative nasal packing in his patients and the two others surgeons did not.Complications and morbidities were compared in these two groups. Comparing the two groups showed that the rate of complication and morbidities between these two groups were same and the differences were not valuable, except the pain and discomfort post operatively and at the time of its removal. Nasal packing has several risks for the patients while its effects are not studied. Septoplasty can be safely performed without postoperative nasal packing. Nasal packing had no main findings that compensated its usage. Septal suture is one of the procedures that can be used as alternative method to nasal packing. Therefore the nasal packing after septoplasty should be reserved for the patients with increased risk of bleeding.

  20. Stabilized quasi-reversibility method for a class of nonlinear ill-posed problems

    Directory of Open Access Journals (Sweden)

    Nguyen Huy Tuan

    2008-06-01

    Full Text Available In this paper, we study a final value problem for the nonlinear parabolic equation $$displaylines{ u_t+Au =h(u(t,t,quad 0problem. We show that the approximate problems are well-posed under certain conditions and that their solutions converges if and only if the original problem has a classical solution. We also obtain estimates for the solutions of the approximate problems, and show a convergence result. This paper extends the work by Hetrick and Hughes [11] to nonlinear ill-posed problems.

  1. A Greedy Algorithm for a Special Class of Geometric Set Covering Problems

    DEFF Research Database (Denmark)

    Stolpe, Mathias; Bechmann, Andreas

    We consider the problem of covering a set of given points in the plane by the smallest number of axis aligned squares of a given fixed size. This problem is of importance for computational fluid dynamics simulations of both onshore and offshore wind turbine parks. For this special case...... of a geometric set covering problem we propose a greedy type algorithm. We also propose a linear mixed 0 – 1 formulation of the problem. For each problem instance this formulation is solved by a commercial branch-andcut solver and the results are used to validate the quality of the solution from the greedy...... algorithm. The greedy algorithm finds the minimum number of squares for all but one problem instances from a set of 26 representative real-world examples....

  2. A Class of Shock Solutions for the Semilinear Singularly Perturbed Boundary Value Problem

    Institute of Scientific and Technical Information of China (English)

    王庚

    2004-01-01

    The shock solution for the semilinear singularly perturbed two-point boundary value problem was studied. Under suitable conditions and using the theory of differential inequalities, the existence and asymptotic behavior of the solution for the original boundary value problems are discussed. The uniformly effective asymptotic expansion and estimation of solution u(x,ε) were obtained.

  3. Nodal Solutions for a Class of Fourth-Order Two-Point Boundary Value Problems

    OpenAIRE

    Xu Jia; Han XiaoLing

    2010-01-01

    We consider the fourth-order two-point boundary value problem , , , where is a parameter, is given constant, with on any subinterval of , satisfies for all , and , , for some . By using disconjugate operator theory and bifurcation techniques, we establish existence and multiplicity results of nodal solutions for the above problem.

  4. 一类半无穷优化问题的求解方法%THE METHOD FOR SOLVING A CLASS OF SEMI-INFINITE PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    孟香惠; 李木桂; 胡新生; 周济; 施保昌

    2001-01-01

    In this paper we present a class of nondifferentiable optimization problems:seim-infinite minimax problems which arise from engineering design. Two algorithms for solving the problems are constructed by combining the idea of discretion with the method for solving minimax problems, and the convergence of the algorithms is proved under weaker conditions. Numerical tests show that the algorithms are practical and effective.

  5. The class actions in italy: problems and perspectives in comparative analysis Le class actions in italia: problemi e prospettive in chiave comparata

    Directory of Open Access Journals (Sweden)

    Gianluca Sgueo

    2008-01-01

    Full Text Available The Italian financial laws for 2008 introduce, in Article 2, item 445, the first organic discipline of class actions in the Italian order. The decision made by the Italian legislator is, therefore, meaningful in relation not only to the effects produced in the legal system but also to the possible repercussions in contractual relations between citizens, companies and local and national public authorities. The article, ideally structured in three parts, puts together a historical reconstruction of the facts before the approval of the law with a detailed analysis of its contents in the light of the most relevant jurisprudential cases. The core of this brief research consists of the analysis of the perspectives as well as their problems, since the analysis of the concrete data tries to discover (possible solutions for such problems.La legge finanziaria italiana per il 2008 introduce, all’articolo 2, comma 445, la prima disciplina organica dell’azione di classe nell’ordinamento italiano. La scelta compiuta dal Legislatore italiano è comunque significativa, sia quanto agli effetti prodotti sul sistema giuridico, sia quanto alle possibili ripercussioni nei rapporti contrattuali tra cittadini, imprese e autorità pubbliche, locali e nazionali. L’articolo, idealmente strutturato in tre parti, combina una ricostruzione storica degli avvenimenti antecedenti all’approvazione della norma di legge in commento con un’analisi più approfondita di quella, alla luce della casistica giurisprudenziale più significativa. È proprio l’analisi delle prospettive e dei problemi Che costituisce il cardine di questa breve ricerca, poiché dall’analisi dei dati concreti tenta di rinvenir e le (possibili soluzioni agli stessi.

  6. Tunable random packings

    International Nuclear Information System (INIS)

    We present an experimental protocol that allows one to tune the packing fraction η of a random pile of ferromagnetic spheres from a value close to the lower limit of random loose packing ηRLP≅0.56 to the upper limit of random close packing ηRCP≅0.64. This broad range of packing fraction values is obtained under normal gravity in air, by adjusting a magnetic cohesion between the grains during the formation of the pile. Attractive and repulsive magnetic interactions are found to affect stongly the internal structure and the stability of sphere packing. After the formation of the pile, the induced cohesion is decreased continuously along a linear decreasing ramp. The controlled collapse of the pile is found to generate various and reproducible values of the random packing fraction η

  7. Diagnosis of class using swarm intelligence applied to problem of identification of nuclear transient

    Energy Technology Data Exchange (ETDEWEB)

    Villas Boas Junior, Manoel; Strauss, Edilberto, E-mail: junior@lmp.ufrj.b [Instituto Federal de Educacao, Ciencia e Tecnologia do Ceara/ Universidade do Estado do Ceara, Itaperi, CE (Brazil). Mestrado Integrado em Computacao Aplicada; Nicolau, Andressa dos Santos; Schirru, Roberto, E-mail: andressa@lmp.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Mello, Flavio Luis de [Universidade Federal do Rio de Janeiro (POLI/UFRJ), RJ (Brazil). Escola Politecnica. Dept. de Engenharia Eletronica e Computacao

    2011-07-01

    This article presents a computational model of the diagnostic system of transient. The model makes use of segmentation techniques applied to support decision making, based on identification of classes and optimized by Particle Swarm Optimization algorithm (PSO). The method proposed aims to classify an anomalous event in the signatures of three classes of the design basis transients postulated for the Angra 2 nuclear plant, where the PSO algorithm is used as a method of separation of classes, being responsible for finding the best centroid prototype vector of each accident/transient, ie equivalent to Voronoi vector that maximizes the number of correct classifications. To make the calculation of similarity between the set of the variables anomalous event in a given time t, and the prototype vector of variables of accident/transients, the metrics of Manhattan, Euclidean and Minkowski were used. The results obtained by the method proposed were compatible with others methods reported in the literature, allowing a solution that approximates the ideal solution, ie the Voronoi vectors. (author)

  8. Development of Generic Field Classes for Finite Element and Finite Difference Problems

    Directory of Open Access Journals (Sweden)

    Diane A. Verner

    1993-01-01

    Full Text Available This article considers the development of a reusable object-oriented array library, as well as the use of this library in the construction of finite difference and finite element codes. The classes in this array library are also generic enough to be used to construct other classes specific to finite difference and finite element methods. We demonstrate the usefulness of this library by inserting it into two existing object-oriented scientific codes developed at Sandia National Laboratories. One of these codes is based on finite difference methods, whereas the other is based on finite element methods. Previously, these codes were separately maintained across a variety of sequential and parallel computing platforms. The use of object-oriented programming allows both codes to make use of common base classes. This offers a number of advantages related to optimization and portability. Optimization efforts, particularly important in large scientific codes, can be focused on a single library. Furthermore, by encapsulating machine dependencies within this library, the optimization of both codes on different architec-tures will only involve modification to a single library.

  9. An Optimal Algorithm for a Class of Parallel Machines Scheduling Problem

    Institute of Scientific and Technical Information of China (English)

    常俊林; 邵惠鹤

    2004-01-01

    This paper considers the parallel machines scheduling problem where jobs are subject to different release times. A constructive heuristic is first proposed to solve the problem in a modest amount of computer time. In general, the quality of the solutions provided by heuristics degrades with the increase of the probiem's scale. Combined the global search ability of genetic algorithm, this paper proposed a hybrid heuristic to improve the quality of solutions further. The computational results show that the hybrid heuristic combines the advantages of heuristic and genetic algorithm effectively and can provide very good solutions to some large problems in a reasonable amount of computer time.

  10. On the Inclusion of Difference Equation Problems and Z Transform Methods in Sophomore Differential Equation Classes

    Science.gov (United States)

    Savoye, Philippe

    2009-01-01

    In recent years, I started covering difference equations and z transform methods in my introductory differential equations course. This allowed my students to extend the "classical" methods for (ordinary differential equation) ODE's to discrete time problems arising in many applications.

  11. Infeasible-interior-point algorithm for a class of nonmonotone complementarity problems and its computational complexity

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents an infeasible-interior-point algorithm for aclass of nonmonotone complementarity problems, and analyses its convergence and computational complexity. The results indicate that the proposed algorithm is a polynomial-time one.

  12. The Expansion of Dynamic Solving Process About a Class of Non-linear Programming Problems

    Institute of Scientific and Technical Information of China (English)

    ZANG Zhen-chun

    2001-01-01

    In this paper, we research non-linear programming problems which have a given specialstructure, some simple forms of this kind structure have been solved in some papers, here we focus on othercomplex ones.

  13. Solvability of a class of second-order quasilinear boundary value problems

    Institute of Scientific and Technical Information of China (English)

    Qing-liu YAO

    2009-01-01

    The second-order quasilinear boundary value problems are considered when the nonlinear term is singular and the limit growth function at the infinite exists. With the introduction of the height function of the nonlinear term on a bounded set and the consideration of the integration of the height function, the existence of the solution is proven. The existence theorem shows that the problem has a solution ff the integration of the limit growth function has an appropriate value.

  14. WEAK REGULARIZATION FOR A CLASS OF ILL-POSED CAUCHY PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This article is concerned with the ill-posed Cauchy problem associated with a densely defined linear operator A in a Banach space. A family of weak regularizing operators is introduced. If the spectrum of A is contained in a sector of right-half complex plane and its resolvent is polynomially bounded, the weak regularization for such ill-posed Cauchy problem can be shown by using the quasi-reversibility method and regularized semigroups. Finally, an example is given.

  15. Mathematical programming based approaches for classes of complex network problems : economical and sociological applications

    OpenAIRE

    Nasini, Stefano

    2015-01-01

    The thesis deals with the theoretical and practical study of mathematical programming methodologies to the analysis complex networks and their application in economic and social problems. More specifically, it applies models and methods for solving linear and integer programming problems to network models exploiting the matrix structure of such models, resulting in efficient computational procedures and small processing time. As a consequence, it allows the study of larger and more complex n...

  16. Second-order cone programming formulations for a class of problems in structural optimization

    OpenAIRE

    Makrodimopoulos, A.; A. Bhaskar; Keane, A.J.

    2010-01-01

    This paper provides efficient and easy to implement formulations for two problems in structural optimization as second-order cone programming (SOCP) problems based on the minimum compliance method and derived using the principle of complementary energy. In truss optimization both single and multiple loads (where we optimize the worst-case compliance) are considered. By using a heuristic which is based on the SOCP duality we can consider a simple ground structure and...

  17. A Special Class of Univalent Functions in Hele-Shaw Flow Problems

    Directory of Open Access Journals (Sweden)

    Paula Curt

    2011-01-01

    Full Text Available We study the time evolution of the free boundary of a viscous fluid for planar flows in Hele-Shaw cells under injection. Applying methods from the theory of univalent functions, we prove the invariance in time of Φ-likeness property (a geometric property which includes starlikeness and spiral-likeness for two basic cases: the inner problem and the outer problem. We study both zero and nonzero surface tension models. Certain particular cases are also presented.

  18. Replacement of the cooling tower packing at the Goesgen-Daeniken AG nuclear power plant

    International Nuclear Information System (INIS)

    In 2005 the asbestos cement cooling tower packing was replaced by plastic material. Two years later, the packing showed strong deformations, deposits of solids and weight gain. At the end of 2007 parts of the packing collapsed into the cooling tower basin. Investigations were made, revealing that the thickness of the packing foil was too low and that packing geometry and biofilms on the surface of the packing favoured deposition of solids. Successful measures were taken to solve the problems. (orig.)

  19. Development of an effective valve packing program

    Energy Technology Data Exchange (ETDEWEB)

    Hart, K.A.

    1996-12-01

    Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

  20. Some Results Connected with the Class Number Problem in Real Quadratic Fields

    Institute of Scientific and Technical Information of China (English)

    Aleksander GRYTCZUK; Jaroslaw GRYTCZUK

    2005-01-01

    We investigate arithmetic properties of certain subsets of square-free positive integers and obtain in this way some results concerning the class number h(d) of the real quadratic field Q(√d). In particular, we give a new proof of the result of Hasse, asserting that in this case h(d) = 1 is possible only if d is of the form p, 2q or qr, where p, q, r are primes and q ≡ r ≡ 3(mod4).

  1. An inverse problem for a class of conditional probability measure-dependent evolution equations

    Science.gov (United States)

    Mirzaev, Inom; Byrne, Erin C.; Bortz, David M.

    2016-09-01

    We investigate the inverse problem of identifying a conditional probability measure in measure-dependent evolution equations arising in size-structured population modeling. We formulate the inverse problem as a least squares problem for the probability measure estimation. Using the Prohorov metric framework, we prove existence and consistency of the least squares estimates and outline a discretization scheme for approximating a conditional probability measure. For this scheme, we prove general method stability. The work is motivated by partial differential equation models of flocculation for which the shape of the post-fragmentation conditional probability measure greatly impacts the solution dynamics. To illustrate our methodology, we apply the theory to a particular PDE model that arises in the study of population dynamics for flocculating bacterial aggregates in suspension, and provide numerical evidence for the utility of the approach.

  2. A non-penalty recurrent neural network for solving a class of constrained optimization problems.

    Science.gov (United States)

    Hosseini, Alireza

    2016-01-01

    In this paper, we explain a methodology to analyze convergence of some differential inclusion-based neural networks for solving nonsmooth optimization problems. For a general differential inclusion, we show that if its right hand-side set valued map satisfies some conditions, then solution trajectory of the differential inclusion converges to optimal solution set of its corresponding in optimization problem. Based on the obtained methodology, we introduce a new recurrent neural network for solving nonsmooth optimization problems. Objective function does not need to be convex on R(n) nor does the new neural network model require any penalty parameter. We compare our new method with some penalty-based and non-penalty based models. Moreover for differentiable cases, we implement circuit diagram of the new neural network.

  3. Interpreting Students' and Teachers' Discourse in Science Classes: An Underestimated Problem?

    Science.gov (United States)

    Klaassen, C. W. J. M.; Lijnse, P. L.

    1996-01-01

    Deals with the problem of the proper interpretation of discourse between students and teachers in classrooms. Presents several interpretations of a concrete classroom protocol in terms of misconceptions. Draws on Davidson's principle of charity and distinguishes between belief and meaning to present an analysis that interprets the discourse…

  4. A TWO-STEP EXPLICIT METHOD FOR A CLASS OF LINEAR PERIODIC INITIAL VALUE PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    李庆宏; 罗亮生; 吴新元

    2003-01-01

    This paper presents a two-step explicit method of order four for solving aclass of linear periodic initial value problems. At each computational step, only tworight function evaluations and one derivative evaluation are employed. Basing on aspecial vector operation, the method can be extended to the vector-applicable in multi-dimensional space.

  5. Problem-Based Learning in an Eleventh Grade Chemistry Class: "Factors Affecting Cell Potential"

    Science.gov (United States)

    Tarhan, Leman; Acar, Burcin

    2007-01-01

    The purpose of this research study was to examine the effectiveness of problem-based learning (PBL) on eleventh grade students' understanding of "The effects of temperature, concentration and pressure on cell potential" and also their social skills. Stratified randomly selected control and experimental groups with 20 students each were used in…

  6. New Class of Solutions for Water Infiltration Problems in Unsaturated Soils

    DEFF Research Database (Denmark)

    Barari, Amin; Omidvar, M; Momeni, M;

    2010-01-01

    This paper presents the results of approximate analytical solutions to Richards’ equation, which governs the problem of unsaturated flow in porous media. The existing methods generally fall within the category of numerical and analytical methods, often having many restrictions for practical situa...

  7. Positive Solutions for a Class of Coupled System of Singular Three-Point Boundary Value Problems

    OpenAIRE

    Naseer Ahmad Asif; Rahmat Ali Khan

    2009-01-01

    Existence of positive solutions for a coupled system of nonlinear three-point boundary value problems of the type , , , , , , , is established. The nonlinearities , are continuous and may be singular at , and/or , while the parameters , satisfy . An example is also included to show the applicability of our result.

  8. Singular Initial Value Problem for Certain Classes of Systems of Ordinary Differential Equations

    Directory of Open Access Journals (Sweden)

    Josef Diblík

    2013-01-01

    dimension of the set of initial data generating such solutions is estimated. An asymptotic behavior of solutions is determined as well and relevant asymptotic formulas are derived. The method of functions defined implicitly and the topological method (Ważewski's method are used in the proofs. The results generalize some previous ones on singular initial value problems for differential equations.

  9. A Class of Constrained Inverse Eigenproblem and Associated Approximation Problem for Symmetric Reflexive Matrices

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Pan; Xiyan Hu; Lei Zhang

    2006-01-01

    Let S ∈ Rn×n be a symmetric and nontrival involution matrix. We say that A ∈ Rn×n is a symmetric reflexive matrix if AT = A and SAS = A. Let SRrn×n(S)={A|A =AT, A = SAS, A ∈ Rn×n}. This paper discusses the following two problems. The first one is as follows.Given Z∈Rn×m (m<n),∧=diag(λ1…,λm)∈Rm×m,and α,β∈R with α<β. Find a subset ψ(Z,A,α,β) of SRrn×n(S) such that AZ = ZA holds for any A∈ ψ(Z,∧,α, β)and the remaining eigenvalues λm+1,…λn of A are located in the interval [α, β]. Moreover, for a given B ∈ Rn×n, the second problem is to find AB ∈ψ(Z, A, α,β)such that ||B-AB||= min A∈ψ(A,∧,α,β) ||B - A||,where ||.|| is the Frobenius norm. Using the properties of symmetric reflexive matrices,the two problems are essentially decomposed into the samekind of subproblems for two real symmetric matrices with smaller dimensions, and then the expressions of the general solution for the two problems are derived.

  10. The Problem of Coherence in English for Business and Technology (EBT) Writing Classes.

    Science.gov (United States)

    Chandrasegaran, Antonia

    1993-01-01

    In business correspondence and technical communications, lack of coherence can cause serious misunderstanding. This paper examines how the problem of generating coherence is addressed in English for Business and Technology textbooks. It proposes a cognitive approach to skill building and presents a teaching procedure for doing so. (Contains two…

  11. Interdisciplinary Explorations: Promoting Critical Thinking via Problem-Based Learning in an Advanced Biochemistry Class

    Science.gov (United States)

    Cowden, Chapel D.; Santiago, Manuel F.

    2016-01-01

    Interdisciplinary approaches to research in the sciences have become increasingly important in solving a wide range of pressing problems at both global and local levels. It is imperative then that science majors in higher education understand the need for exploring information from a wide array of disciplines. With this in mind, interdisciplinary…

  12. Flat Pack Toy Design

    Science.gov (United States)

    Hutcheson, Brian

    2007-01-01

    In this article, the author introduces the concept of flat pack toys. Flat pack toys are designed using a template on a single sheet of letter-sized card stock paper. Before being cut out and built into a three-dimensional toy, they are scanned into the computer and uploaded to a website. With the template accessible from the website, anyone with…

  13. Dynamics of a Dirac oscillator coupled to an external field: a new class of solvable problems

    Energy Technology Data Exchange (ETDEWEB)

    SadurnI, E; Torres, J M; Seligman, T H, E-mail: sadurni@fis.unam.m, E-mail: mau@fis.unam.m, E-mail: seligman@fis.unam.m [Instituto de Ciencias FIsicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico)

    2010-07-16

    The Dirac oscillator coupled to an external two-component field can retain its solvability, if couplings are appropriately chosen. This provides a new class of integrable systems. A simplified way of a solution is given by recasting the known solution of the Dirac oscillator into matrix form; there one notes that a block-diagonal form arises in a Hamiltonian formulation. The blocks are two dimensional. Choosing couplings that do not affect the block structure, these blow up the 2 x 2 matrices to 4 x 4 matrices, thus conserving solvability. The result can be cast again in covariant form. By way of an example we apply this exact solution to calculate the evolution of entanglement.

  14. Dynamics of a Dirac oscillator coupled to an external field: a new class of solvable problems

    Science.gov (United States)

    Sadurní, E.; Torres, J. M.; Seligman, T. H.

    2010-07-01

    The Dirac oscillator coupled to an external two-component field can retain its solvability, if couplings are appropriately chosen. This provides a new class of integrable systems. A simplified way of a solution is given by recasting the known solution of the Dirac oscillator into matrix form; there one notes that a block-diagonal form arises in a Hamiltonian formulation. The blocks are two dimensional. Choosing couplings that do not affect the block structure, these blow up the 2 × 2 matrices to 4 × 4 matrices, thus conserving solvability. The result can be cast again in covariant form. By way of an example we apply this exact solution to calculate the evolution of entanglement.

  15. SIMPLY OPTIMAL - BEYOND EOQ FOR A POPULAR CLASS OF INVENTORY PROBLEMS

    Directory of Open Access Journals (Sweden)

    W. Van Wijck

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: True optimal solution s to real life problems are normally only achievable at the expense of great complexity. Every now and then however, one is almost stunned by the simplicity of a good solution to a practical problem. This paper discusses a relatively simple method for determining the joint optimum order quantity and reorder point for the case where service level is specified as a desired fraction of demand to be satisfied directly from stock. Separate solutions were derived for complete backorders and lost sales, and the method is equally applicable to fixed order quantity and periodic review inventory problems . Demand during the lead time is assumed to be normally distributed . The intent of the paper is to focus on the findings and the application of the method, rather than the mathematical derivation of the formulae itself.

    AFRIKAANSE OPSOMMING: Ware optimale oplossings vir werklike praktiese probleme is gewoonlik net bereikbaar ten koste van groot kompleksiteit. Elke nou en dan staan 'n mens egter bykans verstom omtrerit die eenvoud van 'n voortreflike oplossing vir 'n bepaalde probleem. Hierdie artikel bespreek 'n relatief eenvoudige metode om die gesamentlike optimale bestel-grootte en veiligheidsvoorraad te bepaal, vir die geval waar dienspeil uitgedruk word as die proporsie van voorraad-items wat op eerste aanvraag direk uit voorraad op hande voorsien word. Aparte oplossings is gevind vir die gevalle van volledige agterstallige bestellings en volledige verlore verkope , en die metode is ewe toepaslik vir vaste bestel-hoeveelheid- en periodieke hersiening-voorraad-stelsels. Die normaal-verdeling is as die statistiese verdeling van aanvraag gedurende die leityd aanvaar, Die artikel fokus op toepassing en bevindings eerder as op die wiskundige afleiding van die formules.

  16. Obstacle problem for a class of parabolic equations of generalized p-Laplacian type

    Science.gov (United States)

    Lindfors, Casimir

    2016-11-01

    We study nonlinear parabolic PDEs with Orlicz-type growth conditions. The main result gives the existence of a unique solution to the obstacle problem related to these equations. To achieve this we show the boundedness of weak solutions and that a uniformly bounded sequence of weak supersolutions converges to a weak supersolution. Moreover, we prove that if the obstacle is continuous, so is the solution.

  17. Towards optimal packed string matching

    DEFF Research Database (Denmark)

    Ben-Kiki, Oren; Bille, Philip; Breslauer, Dany;

    2014-01-01

    In the packed string matching problem, it is assumed that each machine word can accommodate up to α characters, thus an n-character string occupies n/α memory words.(a) We extend the Crochemore–Perrin constant-space O(n)-time string-matching algorithm to run in optimal O(n/α) time and even in real......-time, achieving a factor α speedup over traditional algorithms that examine each character individually. Our macro-level algorithm only uses the standard AC0 instructions of the word-RAM model (i.e. no integer multiplication) plus two specialized micro-level AC0 word-size packed-string instructions. The main word...... matching work.(b) We also consider the complexity of the packed string matching problem in the classical word-RAM model in the absence of the specialized micro-level instructions wssm and wslm. We propose micro-level algorithms for the theoretically efficient emulation using parallel algorithms techniques...

  18. On a Boundary-Value Problem for One Class of Differential Equations of the Fourth Order with Operator Coefficients

    CERN Document Server

    Aliev, A R

    2011-01-01

    The boundary-value problem on semi-axis for one class operator-differential equations of the fourth order, the main part of which has the multiple characteristic is investigated in this paper in Sobolev type weighted space. Correctness and unique solvability of the boundary-value problem is proved, and the solvability conditions are expressed in terms of the operator coefficients of the equation. Estimations of the norms of the operators of intermediate derivatives, closely connected with the solvability conditions, have been carried out. The connection between the exponent of the weight and the lower border of the spectrum of the main operator, participating in the equation, is determined in the results of the paper.

  19. An effective numerical method to solve a class of nonlinear singular boundary value problems using improved differential transform method.

    Science.gov (United States)

    Xie, Lie-Jun; Zhou, Cai-Lian; Xu, Song

    2016-01-01

    In this work, an effective numerical method is developed to solve a class of singular boundary value problems arising in various physical models by using the improved differential transform method (IDTM). The IDTM applies the Adomian polynomials to handle the differential transforms of the nonlinearities arising in the given differential equation. The relation between the Adomian polynomials of those nonlinear functions and the coefficients of unknown truncated series solution is given by a simple formula, through which one can easily deduce the approximate solution which takes the form of a convergent series. An upper bound for the estimation of approximate error is presented. Several physical problems are discussed as illustrative examples to testify the validity and applicability of the proposed method. Comparisons are made between the present method and the other existing methods. PMID:27462514

  20. A programme for a problem-free cosmology within the framework of a rich class of scalar-tensor theories

    CERN Document Server

    Lohiya, D; Lohiya, Daksh; Sethi, Meetu

    1999-01-01

    A search for a problem free cosmology within the framework of a finite range theory of gravitation is suggested. We profile a toy model that uses a multicomponent non-minimally coupled scalar tensor theory to achieve this objective. In an SO(2) invariant theory for example, we outline a program that can accommodate a coasting Milne universe with a distribution of non - topological soliton solutions [NTS's]. The interior of these solutions would be domains where effective gravitational effects would be indistinguishable from those expected in standard Einstein theory. For a large class of non - minimal coupling terms and the scalar effective potential, the effective cosmological constant identically vanishes in the region exterior to the NTS's and dynamically approaches a small value in the interior region. We describe features of a problem free cosmology that follows.

  1. Linear one-dimensional cutting-packing problems: numerical experiments with the sequential value correction method (SVC and a modified branch-and-bound method (MBB

    Directory of Open Access Journals (Sweden)

    Mukhacheva E.A.

    2000-01-01

    Full Text Available Two algorithms for the one-dimensional cutting problem, namely, a modified branch-and-bound method (exact method and a heuristic sequential value correction method are suggested. In order to obtain a reliable assessment of the efficiency of the algorithms, hard instances of the problem were considered and from the computational experiment it seems that the efficiency of the heuristic method appears to be superior to that of the exact one, taking into account the computing time of the latter. A detailed description of the two methods is given along with suggestions for their improvements.

  2. 基于图着色模型的冲突装箱问题启发式算法%Heuristic Algorithm for Bin Packing Problem with Conflicts Based on Graph Coloring Model

    Institute of Scientific and Technical Information of China (English)

    元野; 李一军; 王延青; 王晓博

    2013-01-01

    带有冲突关系装箱问题的优化目标是在满足货物冲突关系的前提下,使用数量最少的货箱完成货物装箱的目的。本文分析了冲突装箱问题的数学模型,提出了基于图着色模型的启发式算法进行求解。首先,使用冲突图来描述货物之间的冲突关系;其次,基于冲突图,采取图着色的方式将货物进行分组,并且组内的货物之间不存在冲突关系;最后,采取改进FFD算法对每组的货物进行装箱操作。实验表明,本文提出的启发式算法能够快速有效地找到问题的可行解,为此类装箱问题的求解提供了新思路。%The objection of bin packing problem with conflicts (BPPC)is to minimize the number of bins used to accommodate all the items , and also has to satisfy the conflict constraints among the items .This paper summaries the mathematical model of BPPC , and proposes a heuristic algorithm based on graph coloring model to solve it . Firstly, a conflict graph structure is used to represent the conflict relationship among the items , and then, based on the conflict graph , the algorithm will finish a coloring procedure to group all the items and ensure that there is no items with conflict relationship in each group , and lastly , an improved FFD algorithm is used to complete the packing operation for the items in each group .The experiments show that the algorithm of this paper could find a feasible solution of BPPC quickly and efficiently , and provide a new approach for this kind of bin packing problems .

  3. Storage and treatment of SNF of Alfa class nuclear submarines: current status and problems

    International Nuclear Information System (INIS)

    Available in abstract form only. Full text of publication follows: The current status and main problems associated with storage, defueling and following treatment of spent nuclear fuel (SNF) of Nuclear Submarines (NS) with heavy liquid metal cooled reactors are considered. In the final analysis these solutions could be realized in the form of separate projects to be funded through national and bi- and multilateral funding in the framework of the international collaboration of the Russian Federation on complex utilization of NS and rehabilitation of contaminated objects allocated in the North-West region of Russia. (authors)

  4. On existence of weak solutions to a Cauchy problem for one class of conservation laws

    Directory of Open Access Journals (Sweden)

    P. I. Kogut

    2015-02-01

    Full Text Available We discuss the existence of weak solutions to the Cauchy problem for one classof hyperbolic conservation laws that models a highly re-entrant production system.The output of the factory is described as a function of the work in progress and theposition of the so-called push-pull point (PPP where we separate the beginning ofthe factory employing a push policy from the end of the factory, which uses a pullpolicy. The main question we discuss in this paper is about the optimal choice ofthe input in-ux, push and pull constituents, and the position of PPP.

  5. Reliability and decomposition techniques to solve certain class of stochastic programming problems

    Energy Technology Data Exchange (ETDEWEB)

    Minguez, R., E-mail: Roberto.Minguez@unican.e [Environmental Hydraulics Institute ' IH Cantabria' , Universidad de Cantabria, Cantabria (Spain); Conejo, A.J.; Garcia-Bertrand, R. [Department of Electrical Engineering, University of Castilla-La Mancha, Ciudad Real (Spain)

    2011-02-15

    Reliability based techniques has been an area of active research in structural design during the last decade, and different methods have been developed. The same has occurred with stochastic programming, which is a framework for modeling optimization problems involving uncertainty. The discipline of stochastic programming has grown and broadened to cover a wide range of applications, such as agriculture, capacity planning, energy, finance, fisheries management, production control, scheduling, transportation, water management, etc., and because of this, techniques for solving stochastic programming models are of great interest for the scientific community. This paper presents a new approach for solving a certain type of stochastic programming problems presenting the following characteristics: (i) the joint probability distributions of random variables are given, (ii) these do not depend on the decisions made, and (iii) random variables only affect the objective function. The method is based on mathematical programming decomposition procedures and first-order reliability methods, and constitutes an efficient method for optimizing quantiles in high-dimensional settings. The solution provided by the method allows us to make informed decisions accounting for uncertainty.

  6. Student Perceptions about Group Based Problem Solving Process in Online and In-Class Settings

    Directory of Open Access Journals (Sweden)

    Salih Birişçi

    2013-12-01

    Full Text Available The aim of this study, through qualitative measures, was to systematically examine the perspectives and meanings formed by the teachers about teaching and learning. This study took place in the spring semester of the 2010-2011 academic year of Artvin Çoruh University. The sample size was 27. The participants were divided in two groups – Group 1 with group work taking place in an online test (D1, N=12; Group 2 with group work taking place in a classroom experiment (D2, N=12. After six weeks implementation, semi-structured interviews were conducted in order to determine students’ thoughts on problem solving and group work with success on attitudes towards mathematics. Positive change in students’ attitudes towards mathematics occurred in both the D1 and D2 groups. According to the application, the students stated that they developed increased interest towards mathematics and it turned into enjoyable.Key Words:    Problem solving, group study, online learning, student views

  7. An interactive approach based on a discrete differential evolution algorithm for a class of integer bilevel programming problems

    Science.gov (United States)

    Li, Hong; Zhang, Li; Jiao, Yong-Chang

    2016-07-01

    This paper presents an interactive approach based on a discrete differential evolution algorithm to solve a class of integer bilevel programming problems, in which integer decision variables are controlled by an upper-level decision maker and real-value or continuous decision variables are controlled by a lower-level decision maker. Using the Karush--Kuhn-Tucker optimality conditions in the lower-level programming, the original discrete bilevel formulation can be converted into a discrete single-level nonlinear programming problem with the complementarity constraints, and then the smoothing technique is applied to deal with the complementarity constraints. Finally, a discrete single-level nonlinear programming problem is obtained, and solved by an interactive approach. In each iteration, for each given upper-level discrete variable, a system of nonlinear equations including the lower-level variables and Lagrange multipliers is solved first, and then a discrete nonlinear programming problem only with inequality constraints is handled by using a discrete differential evolution algorithm. Simulation results show the effectiveness of the proposed approach.

  8. Problems and Countermeasures of Colloquial English Large Size Class Teach-ing of Higher Vocational Public English under the Constructivism Theory

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-ping

    2014-01-01

    Based on the theory of constructivism, this article analyzes the open problems colloquial English large size class teach-ing of higher vocational public English and points out the countermeasures of colloquial English large-scale class teaching of high-er vocational public English.

  9. Improved lower bound for online strip packing

    NARCIS (Netherlands)

    Harren, Rolf; Kern, Walter

    2015-01-01

    We study the online strip packing problem and derive an improved lower bound of ρ ≥ 2.589... for the competitive ratio of this problem. The construction is based on modified “Brown-Baker-Katseff sequences” (Brown et al. in Acta Inform. 18:207–225, 1982) using only two types of rectangles. In additio

  10. Extended Kalman Filter with a Fuzzy Method for Accurate Battery Pack State of Charge Estimation

    Directory of Open Access Journals (Sweden)

    Saeed Sepasi

    2015-06-01

    Full Text Available As the world moves toward greenhouse gas reduction, there is increasingly active work around Li-ion chemistry-based batteries as an energy source for electric vehicles (EVs, hybrid electric vehicles (HEVs and smart grids. In these applications, the battery management system (BMS requires an accurate online estimation of the state of charge (SOC in a battery pack. This estimation is difficult, especially after substantial battery aging. In order to address this problem, this paper utilizes SOC estimation of Li-ion battery packs using a fuzzy-improved extended Kalman filter (fuzzy-IEKF for Li-ion cells, regardless of their age. The proposed approach introduces a fuzzy method with a new class and associated membership function that determines an approximate initial value applied to SOC estimation. Subsequently, the EKF method is used by considering the single unit model for the battery pack to estimate the SOC for following periods of battery use. This approach uses an adaptive model algorithm to update the model for each single cell in the battery pack. To verify the accuracy of the estimation method, tests are done on a LiFePO4 aged battery pack consisting of 120 cells connected in series with a nominal voltage of 432 V.

  11. Online Variable-Sized Bin Packing with Conflicts

    DEFF Research Database (Denmark)

    Epstein, Leah; Favrholdt, Lene Monrad; Levin, Asaf

    2011-01-01

    We study a new kind of on-line bin packing with conflicts, motivated by a problem arising when scheduling jobs on the Grid. In this bin packing problem, the set of items is given at the beginning, together with a set of conflicts on pairs of items. A conflict on a pair of items implies...

  12. Nasal packing and stenting

    Directory of Open Access Journals (Sweden)

    Weber, Rainer K.

    2009-01-01

    Full Text Available Nasal packs are indispensable in ENT practice. This study reviews current indications, effectiveness and risks of nasal packs and stents. In endoscopic surgery, nasal packs should always have smooth surfaces to minimize mucosal damage, improve wound healing and increase patient comfort. Functional endoscopic endonasal sinus surgery allows the use of modern nasal packs, since pressure is no longer required. So called hemostatic/resorbable materials are a first step in this direction. However, they may lead to adhesions and foreign body reactions in mucosal membranes. Simple occlusion is an effective method for creating a moist milieu for improved wound healing and avoiding dryness. Stenting of the frontal sinus is recommended if surgery fails to produce a wide, physiologically shaped drainage path that is sufficiently covered by intact tissue.

  13. A class where qualitative discussions, coming weeks before computationally complicated practice, helps students' problem solving abilities

    CERN Document Server

    Webb, D J

    2012-01-01

    Psychologists have long known that an expert in a field not only knows significantly more individual facts/skills than a novice but also has these facts/skills organized into a mental hierarchy that links the individual facts (at the bottom of the hierarchy) together with larger more-encompassing ideas (at the top of the hierarchy). In the Spring quarter of 2012, UC Davis offered 4 sections (about 180 students each) of the first quarter of introductory physics, Physics 9A, covering Newtonian mechanics. One of these sections is a "treatment" group and had the entire 10-week quarter's set of ideas introduced, largely qualitatively, in the first 6 weeks followed by the 4 weeks where students learn to use those ideas to solve the algebraically complicated problems that physicists prize. The other three sections were organized as usual. The treatment group and one of the other sections were taught by the author and were identical (same homework, discussion, lecture, and lab) except for the organization of the cont...

  14. Layered circle packings

    Directory of Open Access Journals (Sweden)

    David Dennis

    2005-01-01

    Full Text Available Given a bounded sequence of integers {d0,d1,d2,…}, 6≤dn≤M, there is an associated abstract triangulation created by building up layers of vertices so that vertices on the nth layer have degree dn. This triangulation can be realized via a circle packing which fills either the Euclidean or the hyperbolic plane. We give necessary and sufficient conditions to determine the type of the packing given the defining sequence {dn}.

  15. Statistical inference for disordered sphere packings

    Directory of Open Access Journals (Sweden)

    Jeffrey Picka

    2012-01-01

    Full Text Available This paper gives an overview of statistical inference for disordered sphere packing processes. These processes are used extensively in physics and engineering in order to represent the internal structure of composite materials, packed bed reactors, and powders at rest, and are used as initial arrangements of grains in the study of avalanches and other problems involving powders in motion. Packing processes are spatial processes which are neither stationary nor ergodic. Classical spatial statistical models and procedures cannot be applied to these processes, but alternative models and procedures can be developed based on ideas from statistical physics.Most of the development of models and statistics for sphere packings has been undertaken by scientists and engineers. This review summarizes their results from an inferential perspective.

  16. Close the Gaps: A Learning-while-Doing Algorithm for a Class of Single-Product Revenue Management Problems

    CERN Document Server

    Wang, Zizhuo; Ye, Yinyu

    2011-01-01

    We present a dynamic learning algorithm for a class of single-product revenue management problems. In these problems, a retailer sells a single product with limited on-hand inventory over a finite selling season. Customer demand arrives according to a Poisson process, the rate of which is influenced by a single action taken by the retailer (such as price adjustment, sales commission, advertisement intensity, etc.). The relation between the action and the demand rate is not known in advance. The retailer will learn the optimal action policy "on the fly" as she maximizes her total expected revenue based on observed demand reactions. Using the pricing problem as an example, we propose a dynamic "learning-while-doing" algorithm to achieve a near optimal performance. Furthermore, we prove that the convergence rate of our algorithm is almost the fastest among all possible algorithms in terms of asymptotic "regret" (the relative loss comparing to the full information optimal solution). Our result closes the performa...

  17. Numerical Simulation of Random Close Packing with Tetrahedra

    Institute of Scientific and Technical Information of China (English)

    LI Shui-Xiang; ZHAO Jian; ZHOU Xuan

    2008-01-01

    The densest packing of tetrahedra is still an unsolved problem.Numerical simulations of random close packing of tetrahedra are carried out with a sphere assembly model and improved relaxation algorithm. The packing density and average contact number obtained for random close packing of regular tetrahedra is 0.6817 and 7.21respectively,while the values of spheres are 0.6435 and 5.95.The simulation demonstrates that tetrahedra can be randomly packed denser than spheres.Random close packings of tetrahedra with a range of height are simulated as well.We find that the regular tetrahedron might be the optimal shape which gives the highest packing density of tetrahedra.

  18. Efficient Algorithm Based on Action Space for Solving the 2D Rectangular Packing Problem%基于动作空间求解二维矩形Packing问题的高效算法∗

    Institute of Scientific and Technical Information of China (English)

    何琨; 黄文奇; 金燕

    2013-01-01

    This paper addresses a typical NP-hard problem, the two-dimensional (2D) rectangular packing problem. The study makes improvements on a quasi-human approach, a caving degree algorithm proposed by Huang Wen-Qi, et al., by defining the conception of action space such that the calculation of the caving degree is simplified. Therefore, the evaluation on different placements is reduced considerably, and good layouts could be obtained quickly. The experiments tested 21 famous instances of the 2D rectangular packing problem provided by Hopper and Turton. The improved algorithm achieved optimal layout with a space utilization of 100% for each instance, and the average computing time on a personal computer was within seven minutes. Computational results show that the improvement strategies on the quasi-human caving degree approach are evident and effective.%  对于二维矩形Packing这一典型的NP难度问题,在黄文奇等人提出的拟人型穴度算法的基础上,通过定义动作空间来简化对不同放入动作的评价,使穴度的计算时间明显缩短,从而使算法能够快速地得到空间利用率较高的布局图案。实验测试了Hopper和Turton提出的21个著名的二维矩形Packing问题的实例。改进的算法对其中的每一个实例都得到了空间利用率为100%的最优布局,且在普通PC机上的平均计算时间未超过7分钟。实验结果表明,基于动作空间对拟人型穴度算法所进行的改进是明显而有效的。

  19. Efficient Algorithm Based on Action Space for Solving the 2D Rectangular Packing Problem%基于动作空间求解二维矩形Packing问题的高效算法

    Institute of Scientific and Technical Information of China (English)

    何琨; 黄文奇; 金燕

    2012-01-01

    对于二维矩形Packing这一典型的NP难度问题,在黄文奇等人提出的拟人型穴度算法的基础上,通过定义动作空间来简化对不同放入动作的评价,使穴度的计算时间明显缩短,从而使算法能够快速地得到空间利用率较高的布局图案.实验测试了Hopper和Turton提出的21个著名的二维矩形Packing问题的实例.改进的算法对其中的每一个实例都得到了空间利用率为100%的最优布局,且在普通PC机上的平均计算时间未超过7分钟.实验结果表明,基于动作空间对拟人型穴度算法所进行的改进是明显而有效的.%This paper addresses a typical NP-hard problem, the two-dimensional (2D) rectangular packing problem. The study makes improvements on a quasi-human approach, a caving degree algorithm proposed by Huang Wen-Qi, et al., by defining the conception of action space such that the calculation of the caving degree is simplified. Therefore, the evaluation on different placements is reduced considerably, and good layouts could be obtained quickly. The experiments tested 21 famous instances of the 2D rectangular packing problem provided by Hopper and Turton. The improved algorithm achieved optimal layout with a space utilization of 100% for each instance, and the average computing time on a personal computer was within seven minutes. Computational results show that the improvement strategies on the quasi-human caving degree approach are evident and effective.

  20. Numerical optimization method for packing regular convex polygons

    Science.gov (United States)

    Galiev, Sh. I.; Lisafina, M. S.

    2016-08-01

    An algorithm is presented for the approximate solution of the problem of packing regular convex polygons in a given closed bounded domain G so as to maximize the total area of the packed figures. On G a grid is constructed whose nodes generate a finite set W on G, and the centers of the figures to be packed can be placed only at some points of W. The problem of packing these figures with centers in W is reduced to a 0-1 linear programming problem. A two-stage algorithm for solving the resulting problems is proposed. The algorithm finds packings of the indicated figures in an arbitrary closed bounded domain on the plane. Numerical results are presented that demonstrate the effectiveness of the method.

  1. Packing of elastic wires in flexible shells

    Science.gov (United States)

    Vetter, R.; Wittel, F. K.; Herrmann, H. J.

    2015-11-01

    The packing problem of long thin filaments that are injected into confined spaces is of fundamental interest for physicists and biologists alike. How linear threads pack and coil is well known only for the ideal case of rigid containers, though. Here, we force long elastic rods into flexible spatial confinement borne by an elastic shell to examine under which conditions recently acquired knowledge on wire packing in rigid spheres breaks down. We find that unlike in rigid cavities, friction plays a key role by giving rise to the emergence of two distinct packing patterns. At low friction, the wire densely coils into an ordered toroidal bundle with semi-ellipsoidal cross-section, while at high friction, it packs into a highly disordered, hierarchic structure. These two morphologies are shown to be separated by a continuous phase transition. Our findings demonstrate the dramatic impact of friction and confinement elasticity on filamentous packing and might drive future research on such systems in physics, biology and even medical technology toward including these mutually interacting effects.

  2. Battery Pack Thermal Design

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, Ahmad

    2016-06-14

    This presentation describes the thermal design of battery packs at the National Renewable Energy Laboratory. A battery thermal management system essential for xEVs for both normal operation during daily driving (achieving life and performance) and off-normal operation during abuse conditions (achieving safety). The battery thermal management system needs to be optimized with the right tools for the lowest cost. Experimental tools such as NREL's isothermal battery calorimeter, thermal imaging, and heat transfer setups are needed. Thermal models and computer-aided engineering tools are useful for robust designs. During abuse conditions, designs should prevent cell-to-cell propagation in a module/pack (i.e., keep the fire small and manageable). NREL's battery ISC device can be used for evaluating the robustness of a module/pack to cell-to-cell propagation.

  3. Some analytical properties of dissolving operators related with the Cauchy problem for a class of nonautonomous partial differential equations. Part 1

    Directory of Open Access Journals (Sweden)

    Marzena Pytel-Kudela

    2006-01-01

    Full Text Available The analytical properties of dissolving operators related with the Cauchy problem for a class of nonautonomous partial differential equations in Hilbert spaces are studied using theory of bi-linear forms in respectively rigged Hilbert spaces triples. Theorems specifying the existence of a dissolving operator for a class of adiabatically perturbed nonautonomous partial differential equations are stated. Some applications of the results obtained are discussed.

  4. Discovery of dominant and dormant genes from expression data using a novel generalization of SNR for multi-class problems

    Directory of Open Access Journals (Sweden)

    Chung I-Fang

    2008-10-01

    Full Text Available Abstract Background The Signal-to-Noise-Ratio (SNR is often used for identification of biomarkers for two-class problems and no formal and useful generalization of SNR is available for multiclass problems. We propose innovative generalizations of SNR for multiclass cancer discrimination through introduction of two indices, Gene Dominant Index and Gene Dormant Index (GDIs. These two indices lead to the concepts of dominant and dormant genes with biological significance. We use these indices to develop methodologies for discovery of dominant and dormant biomarkers with interesting biological significance. The dominancy and dormancy of the identified biomarkers and their excellent discriminating power are also demonstrated pictorially using the scatterplot of individual gene and 2-D Sammon's projection of the selected set of genes. Using information from the literature we have shown that the GDI based method can identify dominant and dormant genes that play significant roles in cancer biology. These biomarkers are also used to design diagnostic prediction systems. Results and discussion To evaluate the effectiveness of the GDIs, we have used four multiclass cancer data sets (Small Round Blue Cell Tumors, Leukemia, Central Nervous System Tumors, and Lung Cancer. For each data set we demonstrate that the new indices can find biologically meaningful genes that can act as biomarkers. We then use six machine learning tools, Nearest Neighbor Classifier (NNC, Nearest Mean Classifier (NMC, Support Vector Machine (SVM classifier with linear kernel, and SVM classifier with Gaussian kernel, where both SVMs are used in conjunction with one-vs-all (OVA and one-vs-one (OVO strategies. We found GDIs to be very effective in identifying biomarkers with strong class specific signatures. With all six tools and for all data sets we could achieve better or comparable prediction accuracies usually with fewer marker genes than results reported in the literature using the

  5. Teaching Large Evening Classes

    Science.gov (United States)

    Wambuguh, Oscar

    2008-01-01

    High enrollments, conflicting student work schedules, and the sheer convenience of once-a-week classes are pushing many colleges to schedule evening courses. Held from 6 to 9 pm or 7 to 10 pm, these classes are typically packed, sometimes with more than 150 students in a large lecture theater. How can faculty effectively teach, control, or even…

  6. Generalization of Youden index for multiple-class classification problems applied to the assessment of externally validated cognition in Parkinson disease screening.

    Science.gov (United States)

    Nakas, Christos T; Dalrymple-Alford, John C; Anderson, Tim J; Alonzo, Todd A

    2013-03-15

    Routine cognitive screening in Parkinson disease (PD) has become essential for management, to track progression and to assess clinical status in therapeutic trials. Patients with mild cognitive impairment (PD-MCI) are more likely to progress to dementia and therefore need to be distinguished from patients with normal cognition and those with dementia. A three-class Youden index has been recently proposed to select cut-off points in three-class classification problems. In this article, we examine properties of a modification of the three-class Youden index and propose a generalization to k-class classification problems. Geometric and theoretical properties of the modified index J(k) are examined. It is shown that J(k) is equivalent to the sum of the k - 1 two-class Youden indices for the adjacent classes of the ordered alternative problem given that the ordering holds. Methods are applied in the assessment of the Montreal Cognitive Assessment test when screening cognition in PD.

  7. DIY Fraction Pack.

    Science.gov (United States)

    Graham, Alan; Graham, Louise

    2003-01-01

    Describes a very successful attempt to teach fractions to year 5 pupils based on pupils making their own fraction pack. Children decided for themselves how to make the fractional slices used in the activity using colored cardboard sheets and templates of a paper circle consisting of 24 equal slices. (Author/NB)

  8. The Six Pack Model

    DEFF Research Database (Denmark)

    Andersen, Henrik; Ritter, Thomas

    Ever seen a growth strategies fail because it was not connect ed to the firm’s customer base? Or a customer relationship strategy falters just because it was the wrong thing to do with that given customer? This article presents the six pack model, a tool that makes growth profitable and predictable...

  9. Optimal online bounded space multidimensional packing

    NARCIS (Netherlands)

    Epstein, L.; Stee, R. van

    2003-01-01

    We solve an open problem in the literature by providing an online algorithm for multidimensional bin packing that uses only bounded space. We show that it is optimal among bounded space algorithms for any dimension $d>1$. Its asymptotic performance ratio is $(Pi_{infty})^d$, where $Pi_{infty}approx1

  10. Damped Arrow-Hurwicz algorithm for sphere packing

    OpenAIRE

    Degond, Pierre; Ferreira, Marina A.; Motsch, Sébastien

    2016-01-01

    We consider algorithms that, from an arbitrarily sampling of $N$ spheres (possibly overlapping), find a close packed configuration without overlapping. These problems can be formulated as minimization problems with non-convex constraints. For such packing problems, we observe that the classical iterative Arrow-Hurwicz algorithm does not converge. We derive a novel algorithm from a multi-step variant of the Arrow-Hurwicz scheme with damping. We compare this algorithm with classical algorithms ...

  11. Rack ‘em, pack 'em and stack ‘em: challenges and opportunities in teaching large classes in higher education [v1; ref status: indexed, http://f1000r.es/nq

    Directory of Open Access Journals (Sweden)

    Saravana Kumar

    2013-02-01

    Full Text Available The higher education sector is undergoing tremendous change, driven by complex driving forces including financial, administrative, and organisational and stakeholder expectations. It is in this challenging environment, educators are required to maintain and improve the quality of teaching and learning outcomes while contending with increasing class sizes. Despite mixed evidence on the effectiveness of large classes on student outcomes, large classes continue to play an important part in higher education. While large classes pose numerous challenges, they also provide opportunities for innovative solutions. This paper provides an overview of these challenges and highlights opportunities for innovative solutions.

  12. Effect of packing method on the randomness of disc packings

    Science.gov (United States)

    Zhang, Z. P.; Yu, A. B.; Oakeshott, R. B. S.

    1996-06-01

    The randomness of disc packings, generated by random sequential adsorption (RSA), random packing under gravity (RPG) and Mason packing (MP) which gives a packing density close to that of the RSA packing, has been analysed, based on the Delaunay tessellation, and is evaluated at two levels, i.e. the randomness at individual subunit level which relates to the construction of a triangle from a given edge length distribution and the randomness at network level which relates to the connection between triangles from a given triangle frequency distribution. The Delaunay tessellation itself is also analysed and its almost perfect randomness at the two levels is demonstrated, which verifies the proposed approach and provides a random reference system for the present analysis. It is found that (i) the construction of a triangle subunit is not random for the RSA, MP and RPG packings, with the degree of randomness decreasing from the RSA to MP and then to RPG packing; (ii) the connection of triangular subunits in the network is almost perfectly random for the RSA packing, acceptable for the MP packing and not good for the RPG packing. Packing method is an important factor governing the randomness of disc packings.

  13. Direct contact condensation in packed beds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yi; Klausner, James F.; Mei, Renwei; Knight, Jessica [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2006-12-15

    A diffusion driven desalination process was recently described where a very effective direct contact condenser with a packed bed is used to condense water vapor out of an air/vapor mixture. A laboratory scale direct contact condenser has been fabricated as a twin tower structure with two stages, co-current and countercurrent. Experiments have been operated in each stage with respective saturated air inlet temperatures of 36, 40 and 43{sup o}C. The temperature and humidity data have been collected at the inlet and exit of the packed bed for different water to air mass flow ratios that vary between 0 and 2.5. A one-dimensional model based on conservation principles has been developed, which predicts the variation of temperature, humidity, and condensation rate through the condenser stages. Agreement between the model and experiments is very good. It is observed that the countercurrent flow stage condensation effectiveness is significantly higher than that for the co-current stage. The condensation heat and mass transfer rates were found to decrease when water blockages occur within the packed bed. Using high-speed digital cinematography, it was observed that this problem can occur at any operating condition, and is dependent on the packing surface wetting characteristics. This observation is used to explain the requirement for two different empirical constants, depending on packing diameter, suggested by Onda for the air side mass transfer coefficient correlation. (author)

  14. Argo packing friction research update

    International Nuclear Information System (INIS)

    This paper focuses on the issue of valve packing friction and its affect on the operability of motor- and air-operated valves (MOVs and AOVs). At this time, most nuclear power plants are required to perform postmaintenance testing following a packing adjustment or replacement. In many cases, the friction generated by the packing does not impact the operability window of a valve. However, to date there has not been a concerted effort to substantiate this claim. To quantify the effects of packing friction, it has become necessary to develop a formula to predict the friction effects accurately. This formula provides a much more accurate method of predicting packing friction than previously used factors based strictly on stem diameter. Over the past 5 years, Argo Packing Company has been developing and testing improved graphite packing systems at research facilities, such as AECL Chalk River and Wyle Laboratories. Much of this testing has centered around reducing and predicting friction that is related to packing. In addition, diagnostic testing for Generic Letter 89-10 MOVs and AOVs has created a significant data base. In July 1992 Argo asked several utilities to provide running load data that could be used to quantify packing friction repeatability and predictability. This technical paper provides the basis to predict packing friction, which will improve calculations for thrust requirements for Generic Leter 89-10 and future AOV programs. In addition, having an accurate packing friction formula will improve packing performance when low running loads are identified that would indicate insufficient sealing force

  15. Separable subgroups have bounded packing

    CERN Document Server

    Yang, Wen-yuan

    2010-01-01

    In this note, we prove that separable subgroups have bounded packing in ambient groups. The notion bounded packing was introduced by Hruska-Wise \\cite{HrWi} and in particular, our result confirms a conjecture in \\cite{HrWi} which states each subgroup of a virtually polycyclic group has the bounded packing property.

  16. Ceramic cooling tower packings

    Energy Technology Data Exchange (ETDEWEB)

    Honekamp, H.; Katzmann, A.

    1986-05-01

    No material for cooling tower packings demonstrates all the characteristics desired by the designer. The choice of a specific material must therefore always be oriented towards the limiting conditions of a specific project. Resistance to frost, combustibility and resistance to ageing may, for example, be determining requirements. Ceramic stones will find further possibilities of application in the near future due to their almost unlimited durability.

  17. Dense Packings of Polyhedra: Platonic and Archimedean Solids

    CERN Document Server

    Torquato, S

    2009-01-01

    We formulate the problem of generating dense packings of nonoverlapping, non-tiling polyhedra within an adaptive fundamental cell subject to periodic boundary conditions as an optimization problem, which we call the Adaptive Shrinking Cell (ASC) scheme. This novel optimization problem is solved here (using a variety of multi-particle initial configurations) to find the dense packings of each of the Platonic solids in three-dimensional Euclidean space R3 , except for the cube, which is the only Platonic solid that tiles space. We find the densest known packings of tetrahedra, icosahedra, dodecahedra, and octahedra with densities 0:823:::, 0:836:::, 0:904:::, and 0:947:::, respectively. It is noteworthy that the densest tetrahedral packing possesses no long-range order. Unlike the densest tetrahedral packing, which must not be a Bravais lattice packing, the densest packings of the other non-tiling Platonic solids that we obtain are their previously known optimal (Bravais) lattice packings. We also derive a simp...

  18. The Problem Is Not Learning: Facilitated Acquisition of Stimulus Equivalence Classes among Low-Achieving College Students

    Science.gov (United States)

    Adcock, Amanda C.; Merwin, Rhonda M.; Wilson, Kelly G.; Drake, Chad E.; Tucker, Christina I.; Elliott, Camden

    2010-01-01

    The present study examines whether facilitated acquisition occurs in contexts when 1 stimulus in a class is emotionally evocative and the other stimuli are arbitrary or neutral. Undergraduates with high and low grade-point averages (GPA) completed a matching-to-sample task that resulted in the formation of 3 stimulus equivalence classes. Each…

  19. Overcoming the Meter Barrier and The Formation of Systems with Tightly-packed Inner Planets (STIPs)

    CERN Document Server

    Boley, Aaron C; Ford, Eric B

    2014-01-01

    We present a solution to the long outstanding meter barrier problem in planet formation theory. As solids spiral inward due to aerodynamic drag, they will enter disk regions that are characterized by high temperatures, densities, and pressures. High partial pressures of rock vapor can suppress solid evaporation, and promote collisions between partially molten solids, allowing rapid growth. This process should be ubiquitous in planet-forming disks, which may be evidenced by the abundant class of Systems with Tightly-packed Inner Planets (STIPs) discovered by the NASA Kepler mission.

  20. OVERCOMING THE METER BARRIER AND THE FORMATION OF SYSTEMS WITH TIGHTLY PACKED INNER PLANETS (STIPs)

    Energy Technology Data Exchange (ETDEWEB)

    Boley, A. C. [Department of Physics and Astronomy, The University of British Columbia, 6224 Agricultural Road, Vancouver, B.C. V6T 1Z1 (Canada); Morris, M. A. [Center for Meteorite Studies, Arizona State University, P.O. Box 876004, Tempe, AZ 88287-6004 (United States); Ford, E. B. [Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

    2014-09-10

    We present a solution to the long outstanding meter barrier problem in planet formation theory. As solids spiral inward due to aerodynamic drag, they will enter disk regions that are characterized by high temperatures, densities, and pressures. High partial pressures of rock vapor can suppress solid evaporation, and promote collisions between partially molten solids, allowing rapid growth. This process should be ubiquitous in planet-forming disks, which may be evidenced by the abundant class of Systems with Tightly packed Inner Planets discovered by the NASA Kepler Mission.

  1. The Holographic study for the high T_c superconductor YBCO and recent development of studies of a class of inverse problems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A dream or interesting problem is to obtain more information based on one measurement,for example to obtain all the thermodynamic functions based on specific heat only. We call it"holographic"study.After more than 10 year's efforts,we suggest one possibility(or only one)is to solve an inverse problem(specific heat-phonon spectrum inversion,SPI).In this talk we will review recent development of studies of a class of inverse problems,including Dai's exact solution and Chen's formula and their unification.T...

  2. Bin Packing via Discrepancy of Permutations

    CERN Document Server

    Eisenbrand, Friedrich; Rothvoß, Thomas

    2010-01-01

    A well studied special case of bin packing is the 3-partition problem, where n items of size >1/4 have to be packed in a minimum number of bins of capacity one. The famous Karmarkar-Karp algorithm transforms a fractional solution of a suitable LP relaxation for this problem into an integral solution that requires at most O(log n) additional bins. The three-permutations-conjecture of Beck is the following. Given any 3 permutations on n symbols, one can color the symbols red and blue, such that in any interval of any of those permutations, the number of red and blue symbols differs only by a constant. Beck's conjecture is well known in the field of discrepancy theory. We establish a surprising connection between bin packing and Beck's conjecture: If the latter holds true, then the additive integrality gap of the 3-partition linear programming relaxation is bounded by a constant. This result indicates that improving approximability results for bin packing requires a better understanding of discrepancy theory.

  3. A Fast Heuristic Parallel Ant Colony Algorithm for Circles Packing Problem with the Equilibrium Constraints%求解平衡约束圆形Packing问题的快速启发式并行蚁群算法

    Institute of Scientific and Technical Information of China (English)

    黎自强; 田茁君; 王奕首; 岳本贤

    2012-01-01

    带平衡约束圆形Packing问题属于NP-hard问题,求解困难.提出一种求解该问题的快速启发式并行蚁群算法.首先提出一种启发式方法:在轮盘赌选择定序的概率公式中增加质量因子和外围逆时针排列定位待布圆,并用它构造出多样性种群个体(相交圆数不超过3的布局方案).然后将蚁群优化与并行搜索相结合,使种群个体快速收敛到最优解或迭代出存在少量干涉的近似最优解(1~3个相交圆).若为后者,则基于物理模型用最速下降法将其快速调整成最优解.所采用的启发式方法、并行蚁群搜索机制和快速调整策略有机结合提高了算法的搜索精度和效率.数值实验表明该算法在性能指标上优于已存在的算法.%Circles packing problem with equilibrium constraints is difficult to solve due to its NP-hard nature. A fast heuristic parallel ant colony algorithm is proposed for this problem. Both circular radius and mass are taken as the probability factors of the roulette selection and the circles are located by arranging round existing circles in peripheral with counter-clockwise movement. Its diverse population individuals (no more than 3 circles are overlapped in each one) are constructed through the proposed heuristic method. The ant colony optimization combined with parallel search mechanism is adopted to obtain an optimal solution or an approximate optimal solution with 1-3 overlapping circles. The steepest descent method based on physical model is used to adjust the approximate optimal solution into the optimal one without overlapping. The combination of heuristic strategy, ant colony search mechanism in parallel, and fast adjustment strategy can improve the computational precision and efficiency of the proposed algorithm. The experiment results show that the proposed algorithm is superior to the existing algorithms in performance.

  4. 合班教学问题与策略探讨%Discussion on Problems and Strategies of Mixed Classes Teaching

    Institute of Scientific and Technical Information of China (English)

    李国红

    2011-01-01

    This paper briefly analyzes and discusses the problems existed in mixed classes teaching, and sums up and puts forward the strategies of mixed classes teaching. It thinks that mixed classes teaching is a kind of universal phenomenon, of which the most outstanding problem is that the teaching effect may be unsatisfied, and the teacher of mixed classes should exert every effort to control classroom order, stir up student's potential, speak fascinating lesson, seek own reason and try to make instructors and monitors of each class to play roles in supervision and management.%文章简要分析与探讨了合班教学存在的问题,归纳和提出了合班教学的策略。认为合班教学是一种普遍现象,其最突出的问题在于教学效果可能不尽如人意,任课教师应从控制课堂秩序、激发学生潜能、把。课讲好、从自身找原因、设法使辅导员和班长发挥其监管作用等方面下功夫。

  5. A modified quasi-boundary value method for a class of abstract parabolic ill-posed problems

    Directory of Open Access Journals (Sweden)

    S. Djezzar

    2006-02-01

    Full Text Available We study a final value problem for first-order abstract differential equation with positive self-adjoint unbounded operator coefficient. This problem is ill-posed. Perturbing the final condition, we obtain an approximate nonlocal problem depending on a small parameter. We show that the approximate problems are well posed and that their solutions converge if and only if the original problem has a classical solution. We also obtain estimates of the solutions of the approximate problems and a convergence result of these solutions. Finally, we give explicit convergence rates.

  6. Using In-class Group Exercises to Enhance Lectures and Provide Introductory Physics Students an Opportunity to Perfect Problem Solving Skills through Interactions with Fellow Students

    Science.gov (United States)

    Trout, Joseph; Bland, Jared

    2013-03-01

    In this pilot project, one hour of lecture time was replaced with one hour of in-class assignments, which groups of students collaborated on. These in-class assignments consisted of problems or projects selected for the calculus-based introductory physics students The first problem was at a level of difficulty that the majority of the students could complete with a small to moderate amount of difficulty. Each successive problem was increasingly more difficult, the last problem being having a level of difficulty that was beyond the capabilities of the majority of the students and required some instructor intervention. The students were free to choose their own groups. Students were encouraged to interact and help each other understand. The success of the in-class exercises were measured using pre-tests and post-tests. The pre-test and post-test were completed by each student independently. Statistics were also compiled on each student's attendance record and the amount of time spent reading and studying, as reported by the student. Statistics were also completed on the student responses when asked if they had sufficient time to complete the pre-test and post-test and if they would have completed the test with the correct answers if they had more time. The pre-tests and post-tests were not used in the computation of the grades of the students.

  7. Cell packing structures

    KAUST Repository

    Pottmann, Helmut

    2015-03-03

    This paper is an overview of architectural structures which are either composed of polyhedral cells or closely related to them. We introduce the concept of a support structure of such a polyhedral cell packing. It is formed by planar quads and obtained by connecting corresponding vertices in two combinatorially equivalent meshes whose corresponding edges are coplanar and thus determine planar quads. Since corresponding triangle meshes only yield trivial structures, we focus on support structures associated with quad meshes or hex-dominant meshes. For the quadrilateral case, we provide a short survey of recent research which reveals beautiful relations to discrete differential geometry. Those are essential for successfully initializing numerical optimization schemes for the computation of quad-based support structures. Hex-dominant structures may be designed via Voronoi tessellations, power diagrams, sphere packings and various extensions of these concepts. Apart from the obvious application as load-bearing structures, we illustrate here a new application to shading and indirect lighting. On a higher level, our work emphasizes the interplay between geometry, optimization, statics, and manufacturing, with the overall aim of combining form, function and fabrication into novel integrated design tools.

  8. Dense packing on uniform lattices

    CERN Document Server

    Eloranta, Kari

    2009-01-01

    We study the Hard Core Model on the graphs ${\\rm {\\bf \\scriptstyle G}}$ obtained from Archimedean tilings i.e. configurations in $\\scriptstyle \\{0,1\\}^{{\\rm {\\bf G}}}$ with the nearest neighbor 1's forbidden. Our particular aim in choosing these graphs is to obtain insight to the geometry of the densest packings in a uniform discrete set-up. We establish density bounds, optimal configurations reaching them in all cases, and introduce a probabilistic cellular automaton that generates the legal configurations. Its rule involves a parameter which can be naturally characterized as packing pressure. It can have a critical value but from packing point of view just as interesting are the noncritical cases. These phenomena are related to the exponential size of the set of densest packings and more specifically whether these packings are maximally symmetric, simple laminated or essentially random packings.

  9. Dimer packings with gaps and electrostatics

    OpenAIRE

    Ciucu, Mihai

    2008-01-01

    Fisher and Stephenson conjectured in 1963 that the correlation function (defined by dimer packings) of two unit holes on the square lattice is rotationally invariant in the limit of large separation between the holes. We consider the same problem on the hexagonal lattice, extend it to an arbitrary finite collection of holes, and present an explicit conjectural answer. In recent work we managed to prove this conjecture in two fairly general cases. The quantity giving the answer can be regarded...

  10. Packing solutions for power plants

    International Nuclear Information System (INIS)

    Asbestos packings are being replaced in more and more countries with alternative products. This paper discusses modern packing solutions for valves and pumps in power plants. Die-moulded packing rings made of expanded graphite foil are described m detail, with recommendations for correct installation. Application examples for spring-loaded valves and cover lid seals are given. As an alternative for repair and service use, a braided expanded graphite packing reinforced with Inconel wire is described. Proposals for sealing various pump applications in power plants are also made. (Author)

  11. Multiple spreading phenomena for a free boundary problem of a reaction-diffusion equation with a certain class of bistable nonlinearity

    Science.gov (United States)

    Kawai, Yusuke; Yamada, Yoshio

    2016-07-01

    This paper deals with a free boundary problem for diffusion equation with a certain class of bistable nonlinearity which allows two positive stable equilibrium states as an ODE model. This problem models the invasion of a biological species and the free boundary represents the spreading front of its habitat. Our main interest is to study large-time behaviors of solutions for the free boundary problem. We will completely classify asymptotic behaviors of solutions and, in particular, observe two different types of spreading phenomena corresponding to two positive stable equilibrium states. Moreover, it will be proved that, if the free boundary expands to infinity, an asymptotic speed of the moving free boundary for large time can be uniquely determined from the related semi-wave problem.

  12. Replacement of the cooling tower packing at the Goesgen-Daeniken AG nuclear power plant; Ersatz der Kuehlturmeinbauten im Kernkraftwerk Goesgen-Daeniken

    Energy Technology Data Exchange (ETDEWEB)

    Rich, Hans Walter [Kernkraftwerk Goesgen-Daeniken AG, Daeniken (Switzerland)

    2012-07-01

    In 2005 the asbestos cement cooling tower packing was replaced by plastic material. Two years later, the packing showed strong deformations, deposits of solids and weight gain. At the end of 2007 parts of the packing collapsed into the cooling tower basin. Investigations were made, revealing that the thickness of the packing foil was too low and that packing geometry and biofilms on the surface of the packing favoured deposition of solids. Successful measures were taken to solve the problems. (orig.)

  13. Random very loose packings.

    Science.gov (United States)

    Ciamarra, Massimo Pica; Coniglio, Antonio

    2008-09-19

    We measure the number Omega(phi) of mechanically stable states of volume fraction phi of a granular assembly under gravity. The granular entropy S(phi)=logOmega(phi) vanishes both at high density, at phi approximately equal to phi_rcp, and a low density, at phi approximately equal to phi_rvlp, where phi_rvlp is a new lower bound we call random very loose pack. phi_rlp is the volume fraction where the entropy is maximal. These findings allow for a clear explanation of compaction experiments and provide the first first-principle definition of the random loose volume fraction. In the context of the statistical mechanics approach to static granular materials, states with phi

  14. Packing for food irradiation

    International Nuclear Information System (INIS)

    Joint FAO/IAEA/WHO Expert Committee approved the use of radiation treatment of foods. Nowadays food packaging are mostly made of plastics, natural or synthetic, therefore effect of irradiation on these materials is crucial for packing engineering for food irradiation technology. By selecting the right polymer materials for food packaging it can be ensured that the critical elements of material and product performance are not compromised. When packaging materials are in contact with food at the time of irradiation that regulatory approvals sometimes apply. The review of the R-and-D and technical papers regarding material selection, testing and approval is presented in the report. The most information come from the USA where this subject is well elaborated, the International Atomic Energy Agency (IAEA) reports are reviewed as well. The report can be useful for scientists and food irradiation plants operators. (author)

  15. Developing and Evaluating Medical Humanities Problem-Based Learning Classes Facilitated by the Teaching Assistants Majored in the Liberal Arts: A Longitudinal Crossover Study.

    Science.gov (United States)

    Tseng, Fen-Yu; Shieh, Jeng-Yi; Kao, Tze-Wah; Wu, Chau-Chung; Chu, Tzong-Shinn; Chen, Yen-Yuan

    2016-02-01

    Although medical humanities courses taught by teachers from nonmedical backgrounds are not unusual now, few studies have compared the outcome of medical humanities courses facilitated by physicians to that by teaching assistants majored in the liberal arts. The objectives of this study were to (1) analyze the satisfaction of medical students with medical humanities problem-based learning (PBL) classes facilitated by nonmedical teaching assistants (TAF) majored in the liberal arts, and those facilitated by the attending physicians (APF) and (2) examine the satisfaction of medical students with clinical medicine-related and clinical medicine-unrelated medical humanities PBL classes.A total of 123 medical students, randomly assigned to 16 groups, participated in this study. There were 16 classes in the course: 8 of them were TAF classes; and the others were APF classes. Each week, each group rotated from 1 subject of the 16 subjects of PBL to another subject. All of the 16 groups went through all the 16 subjects in the 2013 spring semester. We examined the medical students' satisfaction with each class, based on a rating score collected after each class was completed, using a scale from 0 (the lowest satisfaction) to 100 (the highest satisfaction). We also conducted multivariate linear regression analysis to examine the association between the independent variables and the students' satisfaction.Medical students were more satisfied with the TAF (91.35 ± 7.75) medical humanities PBL classes than APF (90.40 ± 8.42) medical humanities PBL classes (P = 0.01). Moreover, medical students were more satisfied with the clinical medicine-unrelated topics (92.00 ± 7.10) than the clinical medicine-related topics (90.36 ± 7.99) in the medical humanities PBL course (P = 0.01).This medical humanities PBL course, including nonmedical subjects and topics, and nonmedical teaching assistants from the liberal arts as class facilitators, was satisfactory. This

  16. Supporting Collaborative Learning and Problem-Solving in a Constraint-Based CSCL Environment for UML Class Diagrams

    Science.gov (United States)

    Baghaei, Nilufar; Mitrovic, Antonija; Irwin, Warwick

    2007-01-01

    We present COLLECT-UML, a constraint-based intelligent tutoring system (ITS) that teaches object-oriented analysis and design using Unified Modelling Language (UML). UML is easily the most popular object-oriented modelling technology in current practice. While teaching how to design UML class diagrams, COLLECT-UML also provides feedback on…

  17. The Local Minima Problem in Hierarchical Classes Analysis: An Evaluation of a Simulated Annealing Algorithm and Various Multistart Procedures

    Science.gov (United States)

    Ceulemans, Eva; Van Mechelen, Iven; Leenen, Iwin

    2007-01-01

    Hierarchical classes models are quasi-order retaining Boolean decomposition models for N-way N-mode binary data. To fit these models to data, rationally started alternating least squares (or, equivalently, alternating least absolute deviations) algorithms have been proposed. Extensive simulation studies showed that these algorithms succeed quite…

  18. Stress, Mental Health, and Substance Abuse Problems in a Sample of Diversion Program Youths: An Exploratory Latent Class Analysis

    Science.gov (United States)

    Dembo, Richard; Briones, Rhissa; Gulledge, Laura; Karas, Lora; Winters, Ken C.; Belenko, Steven; Greenbaum, Paul E.

    2012-01-01

    Reflective of interest in mental health and substance abuse issues among youths involved with the justice system, we performed a latent class analysis on baseline information collected on 100 youths involved in two diversion programs. Results identified two groups of youths: Group 1: a majority of the youths, who had high levels of delinquency,…

  19. The Use of Open-Ended Problem-Based Learning Scenarios in an Interdisciplinary Biotechnology Class: Evaluation of a Problem-Based Learning Course Across Three Years

    Directory of Open Access Journals (Sweden)

    Todd R. Steck

    2012-02-01

    Full Text Available Use of open-ended Problem-Based Learning (PBL in biology classrooms has been limited by the difficulty in designing problem scenarios such that the content learned in a course can be predicted and controlled, the lack of familiarity of this method of instruction by faculty, and the difficulty in assessment. Here we present the results of a study in which we developed a team-based interdisciplinary course that combined the fields of biology and civil engineering across three years. We used PBL scenarios as the only learning tool, wrote the problem scenarios, and developed the means to assess these courses and the results of that assessment. Our data indicates that PBL changed students’ perception of their learning in content knowledge and promoted a change in students’ learning styles. Although no  statistically significant improvement in problem-solving skills and critical thinking skills was observed, students reported substantial changes in their problem-based learning strategies and critical thinking skills.

  20. The use of open-ended problem-based learning scenarios in an interdisciplinary biotechnology class: evaluation of a problem-based learning course across three years.

    Science.gov (United States)

    Steck, Todd R; Dibiase, Warren; Wang, Chuang; Boukhtiarov, Anatoli

    2012-01-01

    Use of open-ended Problem-Based Learning (PBL) in biology classrooms has been limited by the difficulty in designing problem scenarios such that the content learned in a course can be predicted and controlled, the lack of familiarity of this method of instruction by faculty, and the difficulty in assessment. Here we present the results of a study in which we developed a team-based interdisciplinary course that combined the fields of biology and civil engineering across three years. We used PBL scenarios as the only learning tool, wrote the problem scenarios, and developed the means to assess these courses and the results of that assessment. Our data indicates that PBL changed students' perception of their learning in content knowledge and promoted a change in students' learning styles. Although no statistically significant improvement in problem-solving skills and critical thinking skills was observed, students reported substantial changes in their problem-based learning strategies and critical thinking skills. PMID:23653774

  1. Class and Homework Problems: The Break-Even Radius of Insulation Computed Using Excel Solver and WolframAlpha

    Science.gov (United States)

    Foley, Greg

    2014-01-01

    A problem that illustrates two ways of computing the break-even radius of insulation is outlined. The problem is suitable for students who are taking an introductory module in heat transfer or transport phenomena and who have some previous knowledge of the numerical solution of non- linear algebraic equations. The potential for computer algebra,…

  2. The Effects of Authentic Tasks on Preservice Teachers' Attitudes towards Classes and Problem Solving Skills

    Science.gov (United States)

    Kocyigit, Sinan; Zembat, Rengin

    2013-01-01

    This study aimed to investigate the effects of authentic tasks on preschool preservice teachers' attitudes towards the course and problem solving skills. The study was designed in accordance with the pretest-posttest control group model. The data were collected by using the "Problem Solving Skills Inventory", the "Course…

  3. Practical use of SPRINT and a moving grid interface for a class of 1D non-linear transport problems

    NARCIS (Netherlands)

    van Eijkeren JCH; Zegeling PA; Hassanizadeh SM

    1991-01-01

    Environmental problems tend to become of still greater complexity. The mathematical formulation of these problems often results in a set of differential equations, which urges the need for robust differential equation solvers. Moreover, these solvers should be implemented within a user-friendly an

  4. UNIFORM PACKING DIMENSION RESULTS FOR MULTIPARAMETER STABLE PROCESSES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this article, authors discuss the problem of uniform packing dimension of the image set of multiparameter stochastic processes without random uniform H(o)lder condition, and obtain the uniform packing dimension of multiparameter stable processes.If Z is a stable (N, d, α)-process and αN ≤ d, then the following holds with probability 1 Dim Z(E) = α DimE for any Borel setE ∈ B(R+N),where Z(E) = {x: (E) t ∈ E, Z(t) = x}. Dim(E) denotes the packing dimension of E.

  5. Random packing of digitized particles

    NARCIS (Netherlands)

    Korte, de A.C.J.; Brouwers, H.J.H.

    2012-01-01

    The random packing of regularly and irregularly shaped particles has been studied extensively. Within this paper, packing is studied from the perspective of digitized particles. These digitized particles are developed for and used in cellular automata systems, which are employed for the simple mathe

  6. A Hybrid Estimation of Distribution Algorithm and Nelder-Mead Simplex Method for Solving a Class of Nonlinear Bilevel Programming Problems

    Directory of Open Access Journals (Sweden)

    Aihong Ren

    2013-01-01

    Full Text Available We propose a hybrid algorithm based on estimation of distribution algorithm (EDA and Nelder-Mead simplex method (NM to solve a class of nonlinear bilevel programming problems where the follower’s problem is linear with respect to the lower level variable. The bilevel programming is an NP-hard optimization problem, for which EDA-NM is applied as a new tool aiming at obtaining global optimal solutions of such a problem. In fact, EDA-NM is very easy to be implementedsince it does not require gradients information. Moreover, the hybrid algorithm intends to produce faster and more accurate convergence. In the proposed approach, for fixed upper level variable, we make use of the optimality conditions of linear programming to deal with the follower’s problem and obtain its optimal solution. Further, the leader’s objective function is taken as the fitness function. Based on these schemes, the hybrid algorithm is designed by combining EDA with NM. To verify the performance of EDA-NM, simulations on some test problems are made, and the results demonstrate that the proposed algorithm has a better performance than the compared algorithms. Finally, the proposed approach is used to solve a practical example about pollution charges problem.

  7. Sum-Rate Maximization in Two-Way AF MIMO Relaying: Polynomial Time Solutions to a Class of DC Programming Problems

    CERN Document Server

    Khabbazibasmenj, Arash; Vorobyov, Sergiy A; Haardt, Martin

    2012-01-01

    Sum-rate maximization in two-way amplify-and-forward (AF) multiple-input multiple-output (MIMO) relaying belongs to the class of difference-of-convex functions (DC) programming problems. DC programming problems occur as well in other signal processing applications and are typically solved using different modifications of the branch-and-bound method. This method, however, does not have any polynomial time complexity guarantees. In this paper, we show that a class of DC programming problems, to which the sum-rate maximization in two-way MIMO relaying belongs, can be solved very efficiently in polynomial time, and develop two algorithms. The objective function of the problem is represented as a product of quadratic ratios and parameterized so that its convex part (versus the concave part) contains only one (or two) optimization variables. One of the algorithms is called POlynomial-Time DC (POTDC) and is based on semi-definite programming (SDP) relaxation, linearization, and an iterative search over a single para...

  8. A Class of Nonlocal Variational Problems on a Vector Bundle for Color Image Local Contrast Reduction/Enhancement.

    OpenAIRE

    Batard, Thomas; Bertalmío, Marcelo

    2016-01-01

    We extend two existing variational models from the Euclidean space to a vector bundle over a Riemannian manifold. The Euclidean models , dedicated to regularize or enhance some color image features, are based on the concept of nonlocal gradient operator acting on a function of the Euclidean space. We then extend these models by generalizing this operator to a vector bundle over a Riemannian manifold with the help of the parallel transport map associated to some class of covariant derivatives....

  9. A Class of Optimization Method for Bilevel Multi-objective Decision Making Problem with the Help of Satisfactoriness

    Institute of Scientific and Technical Information of China (English)

    LI Tong; TENG Chun-xian; LI Hao-bai

    2002-01-01

    In the paper, it is discussed that the method on how to transform the multi-person bilevel multi-objective decision making problem into the equivalent generalized multi-objective decision making problem by using Kuhn-Tucker sufficient and necessary condition. In order to embody the decision maker's hope and transform it into single-objective decision making problem with the help of e-constraint method.Then we can obtain the global optimal solution by means of simulated annealing algorithm.

  10. Random close packing fractions of lognormal distributions of hard spheres

    OpenAIRE

    Farr, Robert S.

    2013-01-01

    We apply a recent one-dimensional algorithm for predicting random close packing fractions of polydisperse hard spheres [Farr and Groot, J. Chem. Phys. 133, 244104 (2009)] to the case of lognormal distributions of sphere sizes and mixtures of such populations. We show that the results compare well to two much slower algorithms for directly simulating spheres in three dimensions, and show that the algorithm is fast enough to tackle inverse problems in particle packing: designing size distributi...

  11. Evaluation of POE and instructor-led problem-solving approaches integrated into force and motion lecture classes using a model analysis technique

    International Nuclear Information System (INIS)

    This study aims to investigate the use of the predict–observe–explain (POE) approach integrated into large lecture classes on forces and motion. It is compared to the instructor-led problem-solving method using model analysis. The samples are science (SC, N = 420) and engineering (EN, N = 434) freshmen, from Prince of Songkla University, Thailand. Research findings from the force and motion conceptual evaluation indicate that the multimedia-supported POE method promotes students’ learning better than the problem-solving method, in particular for the velocity and acceleration concepts. There is a small shift of the students’ model states after the problem-solving instruction. Moreover, by using model analysis instructors are able to investigate students’ misconceptions and evaluate teaching methods. It benefits instructors in organizing subsequent instructional materials. (paper)

  12. Exact Multiplicity of Positive Solutions for a Class of Second-Order Two-Point Boundary Problems with Weight Function

    OpenAIRE

    Luo Hua; An Yulian

    2010-01-01

    An exact multiplicity result of positive solutions for the boundary value problems , , , is achieved, where is a positive parameter. Here the function is and satisfies , for for some . Moreover, is asymptotically linear and can change sign only once. The weight function is and satisfies , for . Using bifurcation techniques, we obtain the exact number of positive solutions of the problem under consideration for lying in various intervals in . Moreover, we indic...

  13. Packing of protein structures in clusters with magic numbers

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Bohr, Henrik

    1997-01-01

    Recently we have proposed a model for folding proteins into packed `clusters'. We have constructed a local homology measure for protein fold classes by projecting consecutively secondary structures onto a lattice. Taking into account hydrophobic forces we have found a mechanism for formation of...... abundances. In this paper we demonstrate that the results are robust to variations in the coordination number of the model....

  14. Hemiequilibrium problems

    Directory of Open Access Journals (Sweden)

    Muhammad Aslam Noor

    2004-01-01

    Full Text Available We consider a new class of equilibrium problems, known as hemiequilibrium problems. Using the auxiliary principle technique, we suggest and analyze a class of iterative algorithms for solving hemiequilibrium problems, the convergence of which requires either pseudomonotonicity or partially relaxed strong monotonicity. As a special case, we obtain a new method for hemivariational inequalities. Since hemiequilibrium problems include hemivariational inequalities and equilibrium problems as special cases, the results proved in this paper still hold for these problems.

  15. On Packing Densities of Set Partitions

    OpenAIRE

    Goyt, Adam M.; Pudwell, Lara K.

    2013-01-01

    We study packing densities for set partitions, which is a generalization of packing words. We use results from the literature about packing densities for permutations and words to provide packing densities for set partitions. These results give us most of the packing densities for partitions of the set $\\{1,2,3\\}$. In the final section we determine the packing density of the set partition $\\{\\{1,3\\},\\{2\\}\\}$.

  16. Assessing the Social Skills and Problem Behaviors of Adolescents with Severe Disabilities Enrolled in General Education Classes

    Science.gov (United States)

    Lyons, Gregory L.; Huber, Heartley B.; Carter, Erik W.; Chen, Rui; Asmus, Jennifer M.

    2016-01-01

    Although enhancing the social competence of students with severe disabilities has long remained a prominent focus of school-based intervention efforts, relatively little attention has focused on identifying the most critical social and behavioral needs of students during high school. We examined the social skills and problem behaviors of 137…

  17. Assessing the Social Skills and Problem Behaviors of Adolescents With Severe Disabilities Enrolled in General Education Classes.

    Science.gov (United States)

    Lyons, Gregory L; Huber, Heartley B; Carter, Erik W; Chen, Rui; Asmus, Jennifer M

    2016-07-01

    Although enhancing the social competence of students with severe disabilities has long remained a prominent focus of school-based intervention efforts, relatively little attention has focused on identifying the most critical social and behavioral needs of students during high school. We examined the social skills and problem behaviors of 137 adolescents with severe disabilities from the vantage point of both special educators and parents. We sought to identify areas of potential intervention need, explore factors associated with social skill and problem behavior ratings, and examine the extent to which teachers and parents converged in their assessments of these needs. Our findings indicate teachers and parents of high school students with severe disabilities rated social skills as considerably below average and problem behaviors as above average. In addition, lower social skills ratings were evident for students with greater support needs, lower levels of overall adaptive behavior, and a special education label of autism. We found moderate consistency in the degree to which teachers and parents aligned in their assessments of both social skills and problem behavior. We offer recommendations for assessment and intervention focused on strengthening the social competence of adolescents with severe disabilities within secondary school classrooms, as well as promising avenues for future research. PMID:27351700

  18. Perceiving the Problem of Poverty and Schooling: Deconstructing the Class Stereotypes that Mis-Shape Education Practice and Policy

    Science.gov (United States)

    Gorski, Paul C.

    2012-01-01

    A rich history of scholarship has demonstrated the ways in which popular stereotypes of disenfranchised communities, including people living in poverty, affect individual biases and preconceptions. Less attention has been paid to the ways in which such stereotypes help frame policy and practice responses regarding social problems, such as the…

  19. A minimax inequality for a class of functionals and applications to the existence of solutions for two-point boundary-value problems

    Directory of Open Access Journals (Sweden)

    Ghasem Alizadeh Afrouzi

    2006-10-01

    Full Text Available In this paper, we establish an equivalent statement to minimax inequality for a special class of functionals. As an application, we prove the existence of three solutions to the Dirichlet problem $$displaylines{ -u''(x+m(xu(x =lambda f(x,u(x,quad xin (a,b,cr u(a=u(b=0, }$$ where $lambda>0$, $f:[a,b]imes mathbb{R}o mathbb{R}$ is a continuous function which changes sign on $[a,b]imes mathbb{R}$ and $m(xin C([a,b]$ is a positive function.

  20. Problems and Countermeasures in Development of University Class Organization%大学班级组织发展面临的问题及对策

    Institute of Scientific and Technical Information of China (English)

    夏敏

    2012-01-01

    University class is the common teaching organization and management form of university. The development of university class organization is helpful to create the favorable organization atmosphere for the growth of college stfidents, and the realization of the educational objective and higher educational functions. At present, under the influence of university enrolment expansion, educational reform development, and educational concept changes, the form, scope, system and contents of university class organization have been continuously challenged by external development so that the class functions have been weakened, and the management efficiency has been lowered. To change the concept of Class organizational development, to innovate the form of class organization, to broaden the scope of organizational management, and to strengthen the organizational system construction and information construction are the necessary countermeasures for solving the problems of Chinese university class organizational development currently.%大学班级是高校普遍的教学组织和管理形式。大学班级组织的发展有助于创建大学生成长的良好组织氛围,促进教育目标和高等教育功能的实现。当前,大学班级组织在高校扩招、教育改革发展、教育理念变革的影响下,班级组织形式、范围、制度、内容不断受到外部发展的挑战,班级功能弱化,管理效率降低。转变班级组织发展观念,创新班级组织形式,拓宽组织管理范围,加强组织制度建设和信息化建设是应对当前中国大学班级组织发展问题的必要对策。

  1. Lower bounds for 1-, 2- and 3-dimensional on-line bin packing algorithms

    NARCIS (Netherlands)

    G. Galambos; A. van Vliet (André)

    1994-01-01

    textabstractIn this paper we discuss lower bounds for the asymptotic worst case ratio of on-line algorithms for different kind of bin packing problems. Recently, Galambos and Frenk gave a simple proof of the 1.536 ... lower bound for the 1-dimensional bin packing problem. Following their ideas, we p

  2. A New Algorithm Based on the Homotopy Perturbation Method For a Class of Singularly Perturbed Boundary Value Problems

    Directory of Open Access Journals (Sweden)

    A New Algorithm Based on the Homotopy Perturbation Method For a Class of Singularly Perturbed Boundary Value Problems

    2013-12-01

    Full Text Available . In this paper, a new algorithm is presented to approximate the solution of a singularly perturbed boundary value problem with leftlayer based on the homotopy perturbation technique and applying the Laplace transformation. The convergence theorem and the error bound of the proposed method are proved. The method is examined by solving two examples. The results demonstrate the reliability and efficiency of the proposed method.

  3. On the theory of generalized entropy solutions of the Cauchy problem for a class of non-strictly hyperbolic systems of conservation laws

    International Nuclear Information System (INIS)

    Many-dimensional non-strictly hyperbolic systems of conservation laws with a radially degenerate flux function are considered. For such systems the set of entropies is defined and described, the concept of generalized entropy solution of the Cauchy problem is introduced, and the properties of generalized entropy solutions are studied. The class of strong generalized entropy solutions is distinguished, in which the Cauchy problem in question is uniquely soluble. A condition on the initial data is described that ensures that the generalized entropy solution is strong and therefore unique. Under this condition the convergence of the 'vanishing viscosity' method is established. An example presented in the paper shows that a generalized entropy solution is not necessarily unique in the general case

  4. Improving student's problem-solving ability as well as conceptual understanding without sacrificing the physics content of a class

    CERN Document Server

    Webb, D J

    2012-01-01

    Four sections of introductory physics for physical scientists and engineers (about 180 students each) are compared. One section, treatment group, was organized so that students worked to learn the classical ideas connecting forces and motion over the first 6 weeks of the 10 week quarter and then used the final 4 weeks to apply those principles to algebraically complicated problems. The other sections learned ideas at essentially the same time as calculations over the entire 10 weeks of the quarter. The treatment group and one of the control sections were taught by the same instructor, had identical curricular materials and this instructor was blind to the comparison measure, the final exam. After controlling for GPA as well as for incoming conceptual understanding, the treatment group was found (with greater than 99% confidence) to perform better on the final exam than the control group taught by the same instructor and, by a similar measure, the treatment group performed significantly better than any other s...

  5. An Optimizing Space Data-Communications Scheduling Method and Algorithm with Interference Mitigation, Generalized for a Broad Class of Optimization Problems

    Science.gov (United States)

    Rash, James

    2014-01-01

    NASA's space data-communications infrastructure-the Space Network and the Ground Network-provide scheduled (as well as some limited types of unscheduled) data-communications services to user spacecraft. The Space Network operates several orbiting geostationary platforms (the Tracking and Data Relay Satellite System (TDRSS)), each with its own servicedelivery antennas onboard. The Ground Network operates service-delivery antennas at ground stations located around the world. Together, these networks enable data transfer between user spacecraft and their mission control centers on Earth. Scheduling data-communications events for spacecraft that use the NASA communications infrastructure-the relay satellites and the ground stations-can be accomplished today with software having an operational heritage dating from the 1980s or earlier. An implementation of the scheduling methods and algorithms disclosed and formally specified herein will produce globally optimized schedules with not only optimized service delivery by the space data-communications infrastructure but also optimized satisfaction of all user requirements and prescribed constraints, including radio frequency interference (RFI) constraints. Evolutionary algorithms, a class of probabilistic strategies for searching large solution spaces, is the essential technology invoked and exploited in this disclosure. Also disclosed are secondary methods and algorithms for optimizing the execution efficiency of the schedule-generation algorithms themselves. The scheduling methods and algorithms as presented are adaptable to accommodate the complexity of scheduling the civilian and/or military data-communications infrastructure within the expected range of future users and space- or ground-based service-delivery assets. Finally, the problem itself, and the methods and algorithms, are generalized and specified formally. The generalized methods and algorithms are applicable to a very broad class of combinatorial

  6. Nature of packs used in propellant modeling.

    Science.gov (United States)

    Maggi, F; Stafford, S; Jackson, T L; Buckmaster, J

    2008-04-01

    In recent years we have constructed closely packed spheres using the Lubachevsky-Stillinger algorithm to generate morphological models of heterogeneous solid propellants. Improvements to the algorithm now allow us to create large polydisperse packs on a laptop computer, and to create monodisperse packs with packing fractions greater than 70% which display significant crystal order. The use of these models in the physical context motivates efforts to examine in some detail the nature of the packs, including certain statistical properties. We compare packing fractions for binary packs with long-known experimental data. Also, we discuss the near-neighbor number and the radial distribution function (RDF) for monodisperse packs and make comparisons with experimental data. We also briefly discuss the RDF for bidisperse packs. We also consider bounded monodisperse packs, and pay particular attention to the near-wall structure where we identify significant order.

  7. Dosimetry effects of film packing

    International Nuclear Information System (INIS)

    Full text: Dosimetric artefacts in film based dosimetry have been addressed by a number of authors. We have investigated the influence on film dose results, of a number of materials that are commonly packed against the film including, solid water, paper, air and plastic. The results indicate that variations in optical density occur due to the character and relative quantity of the packing material as well as the film itself. Kodak X-omat V and GAFChromic film samples were placed in a solid water cassette with packing sheets of various materials placed in contact with the film. Photon and electron exposures were carried out with various film orientation and beam qualities. Results have been obtained for solid water, paper and air. An example of the relative change in film density as a function of depth due to four paper sheets packed adjacent to a film aligned with the central axis of a 6MV photon beam is shown. Other results indicate dose variation can be attributed to Cerenkov radiation. Packing materials in contact or in close proximity with dosimetric film, contribute to optical density variations of the order of several percent. Careful consideration of these effects is necessary when using film in high accuracy dosimetry. Copyright (2001) Australasian College of Physical Scientists and Engineers in Medicine

  8. Sleeping distance in wild wolf packs

    Science.gov (United States)

    Knick, S.T.; Mech, L.D.

    1980-01-01

    Sleeping distances were observed among members of 13 wild wolf (Canis lupus) packs and 11 pairs in northeastern Minnesota to determine if the distances correlated with pack size and composition. The study utilized aerial radio-tracking and observation during winter. Pack size and number of adults per pack were inversely related to pack average sleeping distance and variability. No correlation between sleeping distance and microclimate was observed. Possible relationships between social bonding and our results are discussed.

  9. A Problem on the Addition of Residue Classes by Sark?zy%Sark?zy的一个加法剩余类问题

    Institute of Scientific and Technical Information of China (English)

    杨仕椿; 汤建钢

    2013-01-01

    The characteristic of the A+B and A+^B,is a difficult topic in number theory and combinatorics,and plays an important and profound role. In this paper,we first noted that under normal circumstances,the answer of a problem on the addition of residue classes by Sark?zy is negative. Secondly,for the mode even number m of irreducible residue system, using Cauchy-Davenport theorem,we give the problem in two preliminary results when m=2 p,2k p(k≥2),where p is a prime number. Finally,we presented some problems and conjectures to be studied.%关于A+B以及A+^B的性质问题,一直是数论与组合数学中的困难课题和重要问题。本文首先指出,在一般情况下,关于Sark?zy的一个加法剩余类猜想的答案是否定的。其次,对于模偶数 m的既约剩余系,利用Cauchy-Davenport定理,给出当m=2p,2kp(k≥2)时该问题的两个初步的结果,这里p为素数。最后,提出一些待研究的问题和猜想。

  10. Cylinder valve packing nut studies

    Energy Technology Data Exchange (ETDEWEB)

    Blue, S.C. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    The design, manufacture, and use of cylinder valve packing nuts have been studied to improve their resistance to failure from stress corrosion cracking. Stress frozen photoelastic models have been analyzed to measure the stress concentrations at observed points of failure. The load effects induced by assembly torque and thermal expansion of stem packing were observed by strain gaging nuts. The effects of finishing operations and heat treatment were studied by the strain gage hole boring and X-ray methods. Modifications of manufacturing and operation practices are reducing the frequency of stress corrosion failures.

  11. School meal sociality or lunch pack individualism?

    DEFF Research Database (Denmark)

    Andersen, Sidse Schoubye; Holm, Lotte; Baarts, Charlotte

    2015-01-01

    the social life of a school class, and how these arrangements involve strategies of both inclusion and exclusion. Two types of school meals are compared in the intervention study: a hot meal based on Nordic ingredients and the normal Danish school meal arrangement in which children bring lunch packs...... to school. The study discusses commensality by examining and comparing lunchtime interactions within the same group of children in the two contrasting meal situations. The results fail to confirm the conventional view that shared meals have greater social impacts and benefits than eating individualized......The present article specifies and broadens our understanding of the concept of commensality by investigating what it means to ‘share a meal’. The study utilizes a school meal intervention carried out in Denmark in 2011/2012. It shows how different types of school meal arrangement influence...

  12. A Geometric-Structure Theory for Maximally Random Jammed Packings

    Science.gov (United States)

    Tian, Jianxiang; Xu, Yaopengxiao; Jiao, Yang; Torquato, Salvatore

    2015-11-01

    Maximally random jammed (MRJ) particle packings can be viewed as prototypical glasses in that they are maximally disordered while simultaneously being mechanically rigid. The prediction of the MRJ packing density ϕMRJ, among other packing properties of frictionless particles, still poses many theoretical challenges, even for congruent spheres or disks. Using the geometric-structure approach, we derive for the first time a highly accurate formula for MRJ densities for a very wide class of two-dimensional frictionless packings, namely, binary convex superdisks, with shapes that continuously interpolate between circles and squares. By incorporating specific attributes of MRJ states and a novel organizing principle, our formula yields predictions of ϕMRJ that are in excellent agreement with corresponding computer-simulation estimates in almost the entire α-x plane with semi-axis ratio α and small-particle relative number concentration x. Importantly, in the monodisperse circle limit, the predicted ϕMRJ = 0.834 agrees very well with the very recently numerically discovered MRJ density of 0.827, which distinguishes it from high-density “random-close packing” polycrystalline states and hence provides a stringent test on the theory. Similarly, for non-circular monodisperse superdisks, we predict MRJ states with densities that are appreciably smaller than is conventionally thought to be achievable by standard packing protocols.

  13. Pack cementation coatings for alloys

    Energy Technology Data Exchange (ETDEWEB)

    He, Yi-Rong; Zheng, Minhui; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States)

    1996-08-01

    The halide-activated pack cementation process was modified to produce a Ge-doped silicide diffusion coating on a Cr-Cr{sub 2}Nb alloy in a single processing step. The morphology and composition of the coating depended both on the composition of the pack and on the composition and microstructure of the substrate. Higher Ge content in the pack suppressed the formation of CrSi{sub 2} and reduced the growth kinetics of the coating. Ge was not homogeneously distributed in the coatings. In cyclic and isothermal oxidation in air at 700 and 1050{degrees}C, the Ge-doped silicide coating protected the Cr-Nb alloys from significant oxidation by the formation of a Ge-doped silica film. The codeposition and diffusion of aluminum and chromium into low alloy steel have been achieved using elemental Al and Cr powders and a two-step pack cementation process. Sequential process treatments at 925{degrees}C and 1150{degrees}C yield dense and uniform ferrite coatings, whose compositions are close to either Fe{sub 3}Al or else FeAl plus a lower Cr content, when processed under different conditions. The higher content of Al in the coatings was predicted by thermodynamic calculations of equilibrium in the gas phase. The effect of the particle size of the metal powders on the surface composition of the coating has been studied for various combinations of Al and Cr powders.

  14. Nearly-Linear Time Packing and Covering LP Solvers

    OpenAIRE

    Allen-Zhu, Zeyuan; Orecchia, Lorenzo

    2014-01-01

    Packing and covering linear programs (PC-LPs) form an important class of linear programs (LPs) across computer science, operations research, and optimization. In 1993, Luby and Nisan constructed an iterative first-order algorithm for approximately solving PC-LPs in $\\textit{nearly-linear time}$, independently of the program's $\\textit{width}$, i.e., the largest value in the program's description. Unfortunately, all existing nearly-linear-time algorithms for solving PC-LPs require time at leas...

  15. The close-packed triple helix as a possible new structural motif for collagen

    DEFF Research Database (Denmark)

    Bohr, Jakob; Olsen, Kasper

    2010-01-01

    The one-dimensional problem of selecting the triple helix with the highest volume fraction is solved and hence the condition for a helix to be close-packed is obtained. The close-packed triple helix is shown to have a pitch angle of v CP = 43.3°. Contrary to the conventional notion, we suggest th...

  16. Packing Different Cuboids with Rotations and Spheres into a Cuboid

    Directory of Open Access Journals (Sweden)

    Y. G. Stoyan

    2014-01-01

    Full Text Available The paper considers a packing optimization problem of different spheres and cuboids into a cuboid of the minimal height. Translations and continuous rotations of cuboids are allowed. In the paper, we offer a way of construction of special functions (Φ-functions describing how rotations can be dealt with. These functions permit us to construct the mathematical model of the problem as a classical mathematical programming problem. Basic characteristics of the mathematical model are investigated. When solving the problem, the characteristics allow us to apply a number of original and state-of-the-art efficient methods of local and global optimization. Numerical examples of packing from 20 to 300 geometric objects are given.

  17. Measured black carbon deposition on the Sierra Nevada snow pack and implication for snow pack retreat

    Directory of Open Access Journals (Sweden)

    O. L. Hadley

    2010-08-01

    Full Text Available Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.

  18. Measured black carbon deposition on the Sierra Nevada snow pack and implication for snow pack retreat

    Directory of Open Access Journals (Sweden)

    O. L. Hadley

    2010-04-01

    Full Text Available Modeling studies show that the darkening of snow and ice by black carbon (BC deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition on the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.

  19. Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

    Energy Technology Data Exchange (ETDEWEB)

    Hadley, O.L.; Corrigan, C.E.; Kirchstetter, T.W.; Cliff, S.S.; Ramanathan, V.

    2010-01-12

    Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.

  20. A genetic programming hyper-heuristic approach to automated packing

    OpenAIRE

    Hyde, Matthew

    2010-01-01

    This thesis presents a programme of research which investigated a genetic programming hyper-heuristic methodology to automate the heuristic design process for one, two and three dimensional packing problems. Traditionally, heuristic search methodologies operate on a space of potential solutions to a problem. In contrast, a hyper-heuristic is a heuristic which searches a space of heuristics, rather than a solution space directly. The majority of hyper-heuristic research papers, so far, hav...

  1. Performance characteristics of a new structured packing

    OpenAIRE

    Bessou, Vincent; Rouzineau, David; Prevost, Michel; Abbé, François; Dumont, Charles; Maumus, Jean-Pierre; Meyer, Michel

    2010-01-01

    A new structured packing using carbon fibres, called Sepcarb® 4D, is presented. This packing has several attractive properties, such as high voidage (ε=94%) and high effective area (a=420 m2 m−3). These properties are advantageous for packing used as a gas–liquid contactor for separation units. To determine the internal characteristics of this packing, we performed several experiments using a 150-mm-internal-diameter column. Firstly, hydrodynamics experiments were conducted using an air–water...

  2. Packing Superballs from Codes and Algebraic Curves

    Institute of Scientific and Technical Information of China (English)

    Li LIU; Chao Ping XING

    2008-01-01

    In the present paper, we make use of codes with good parameters and algebraic curves over finite fields with many rational points to construct dense packings of superballs. It turns out that our packing density is quite reasonable. In particular, we improve some values for the best-known lower bounds on packing density.

  3. 7 CFR 51.1527 - Standard pack.

    Science.gov (United States)

    2010-01-01

    ... package. The number of plums or prunes in California peach boxes or lug boxes shall not vary more than 4... Standards for Grades of Fresh Plums and Prunes Standard Pack § 51.1527 Standard pack. (a) Packing. (1) All... plums or prunes in the top layer of any package shall be reasonably representative in quality and...

  4. Random packing of colloids and granular matter

    NARCIS (Netherlands)

    Wouterse, A.

    2008-01-01

    This thesis deals with the random packing of colloids and granular matter. A random packing is a stable disordered collection of touching particles, without long-range positional and orientational order. Experimental random packings of particles with the same shape but made of different materials sh

  5. 7 CFR 51.310 - Packing requirements.

    Science.gov (United States)

    2010-01-01

    ... MARKETING ACT OF 1946 FRESH FRUITS, VEGETABLES AND OTHER PRODUCTS 1,2 (INSPECTION, CERTIFICATION, AND.... (a) Apples tray packed or cell packed in cartons shall be arranged according to approved and... that apples are of the proper size for molds or cell compartments in which they are packed, and...

  6. Diffusion in Jammed Particle Packs.

    Science.gov (United States)

    Bolintineanu, Dan S; Grest, Gary S; Lechman, Jeremy B; Silbert, Leonardo E

    2015-08-21

    Using random walk simulations we explore diffusive transport through monodisperse sphere packings over a range of packing fractions ϕ in the vicinity of the jamming transition at ϕ(c). Various diffusion properties are computed over several orders of magnitude in both time and packing pressure. Two well-separated regimes of normal "Fickian" diffusion, where the mean squared displacement is linear in time, are observed. The first corresponds to diffusion inside individual spheres, while the latter is the long-time bulk diffusion. The intermediate anomalous diffusion regime and the long-time value of the diffusion coefficient are both shown to be controlled by particle contacts, which in turn depend on proximity to ϕ(c). The time required to recover normal diffusion t* scales as (ϕ-ϕ(c))(-0.5) and the long-time diffusivity D(∞)∼(ϕ-ϕ(c))0.5, or D(∞)∼1/t*. It is shown that the distribution of mean first passage times associated with the escape of random walkers between neighboring particles controls both t* and D(∞) in the limit ϕ→ϕ(c).

  7. “90后”大学生班级管理中的问题及对策研究%Research on the Problems and Countermeasures of Class Management for College Students after 90s

    Institute of Scientific and Technical Information of China (English)

    解滨羽

    2012-01-01

    By the work of class teachers, to collect information and student-depth interviews, study on "90" college students' class, found the problems that: the lack of a culture of learning classes, in class time, students' serious mobile Internet; class lack of cohesion, the students do not positive participate in class activities; students' low self-discipline, morning exercises and study up attendance is poor; the class poverty gap. And put forward corresponding countermeasures for the above problems.%通过班主任工作,收集资料和学生深度访谈,文章就"90后"大学生班级进行了研究,发现存在的问题有:班级学习风气不足,上课时间学生手机上网现象严重;班级缺乏凝聚力,学生参加班级活动不积极;学生自我约束力低,早操和晚自习出勤较差;班级贫富差距较大。并针对以上问题提出了相应的对策。

  8. Latent Class Analysis of Gambling Activities in a Sample of Young Swiss Men: Association with Gambling Problems, Substance Use Outcomes, Personality Traits and Coping Strategies.

    Science.gov (United States)

    Studer, Joseph; Baggio, Stéphanie; Mohler-Kuo, Meichun; Simon, Olivier; Daeppen, Jean-Bernard; Gmel, Gerhard

    2016-06-01

    The study aimed to identify different patterns of gambling activities (PGAs) and to investigate how PGAs differed in gambling problems, substance use outcomes, personality traits and coping strategies. A representative sample of 4989 young Swiss males completed a questionnaire assessing seven distinct gambling activities, gambling problems, substance use outcomes, personality traits and coping strategies. PGAs were identified using latent class analysis (LCA). Differences between PGAs in gambling and substance use outcomes, personality traits and coping strategies were tested. LCA identified six different PGAs. With regard to gambling and substance use outcomes, the three most problematic PGAs were extensive gamblers, followed by private gamblers, and electronic lottery and casino gamblers, respectively. By contrast, the three least detrimental PGAs were rare or non-gamblers, lottery only gamblers and casino gamblers. With regard to personality traits, compared with rare or non-gamblers, private and casino gamblers reported higher levels of sensation seeking. Electronic lottery and casino gamblers, private gamblers and extensive gamblers had higher levels of aggression-hostility. Extensive and casino gamblers reported higher levels of sociability, whereas casino gamblers reported lower levels of anxiety-neuroticism. Extensive gamblers used more maladaptive and less adaptive coping strategies than other groups. Results suggest that gambling is not a homogeneous activity since different types of gamblers exist according to the PGA they are engaged in. Extensive gamblers, electronic and casino gamblers and private gamblers may have the most problematic PGAs. Personality traits and coping skills may predispose individuals to PGAs associated with more or less negative outcomes. PMID:25929440

  9. Packing of charged chains on toroidal geometries

    Science.gov (United States)

    Yao, Zhenwei; de la Cruz, Monica Olvera

    2013-01-01

    We study a strongly adsorbed flexible polyelectrolyte chain on tori. In this generalized Thomson problem, the patterns of the adsorbed chain are analyzed in the space of the toroidal coordinates and in terms of the orientation of each chain segment. Various patterns are found, including double spirals, disclination-like structures, Janus tori, and uniform wrappings, arising from the long-range electrostatic interaction and the toroidal geometry. Their broken mirror symmetry is quantitatively characterized by introducing an order parameter, an integral of the torsion. The uniform packing, which breaks the mirror symmetry the least, has the lowest value of the order parameter. In addition, it is found that the electrostatic energy of confined chains on tori conforms to a power law regardless of the screening effect in some typical cases studied. Furthermore, we study random walks on tori that generate chain configurations in the large screening limit or at large thermal fluctuation; some features associated with the toroidal geometry are discussed.

  10. Solving a Class of Brouwer Fixed-point Problems via a Modified Aggregate Constraint Homotopy Method%用改进的凝聚约束同伦方法求解一类Brouwer不动点问题

    Institute of Scientific and Technical Information of China (English)

    苏孟龙; 吕显瑞

    2007-01-01

    In this paper, we provide an aggregate function homotopy interior point method to solve a class of Brouwer fixed-point problems. Compared with the homotopy method (proposed by Yu and Lin, Appl. Math. Comput., 74(1996), 65), the main adavantages of this method are as follows: on the one hand, it can solve the Brouwer fixed-point problems in a broader class of nonconvex subsets Ω in Rn (in this paper, we let Ω = [x ∈ Rn: gi(x) ≤ 0, i = 1,… ,m]); on the other hand, it can also deal with the subsets Ω with larger amount of constraints more effectively.

  11. On a class of functional equations of the Wiener-Hopf type and their applications in n-part scattering problems

    Science.gov (United States)

    Idemen, Mithat; Alkumru, Ali

    2003-12-01

    An asymptotic theory for the functional equation K{phi} = f, where K : X [->] Y stands for a matrix-valued linear operator of the form K = K1P1 + K2P2 + ... + KnPn, is developed. Here X and Y refer to certain Hilbert spaces, {P{alpha}} denotes a partition of the unit operator in X while K{alpha} are certain operators from X to Y. One assumes that the partition {P{alpha}} as well as the operators K{alpha} depend on a complex parameter {nu} such that all K{alpha} are multi-valued around certain branch points at {nu} = k+ and {nu} = k- while the inverse operators K-1{alpha} exist and are bounded in the appropriately cut {nu}-plane except for certain poles. Then, for a class of {P{alpha}} having certain analytical properties, an asymptotic solution valid for |k{+/-}| [->] {infty} is given. The basic idea is the decomposition of {phi} into a sum of projections on n mutually orthogonal subspaces of X. The results can be extended in a straightforward manner to the cases of no or more branch points. If there is no branch point or n = 2, then the results are all exact. The theory may have effective applications in solving some direct and inverse multi-part boundary-value problems connected with high-frequency waves. An illustrative example shows the applicability as well as the effectiveness of the method.

  12. A Quasi-physical Algorithm Based on Coarse and Fine Adjustment for Solving Circles Packing Problem with Constraints of Equilibrium%基于粗精调技术的求解带平衡约束圆形Packing问题的拟物算法

    Institute of Scientific and Technical Information of China (English)

    何琨; 莫旦增; 许如初; 黄文奇

    2013-01-01

    The circles packing problem with constraints of equilibrium,as a two-dimensional packing problem with the background of satellite module layout design,is an NP hard layout optimization problem.A mathematical model and two new physical models are established for this problem.And inspired by the process of coarse and fine adjustment in the industry,a QuasiPhysical algorithm based on Coarse and Fine Adjustment (QPCFA) is proposed.Not only can QPCFA keep the diversity of the searching space to facilitate the global search,but also it can do fine search in promising local areas to find the corresponding local optimal solutions.Moreover,the taboo method and the jump pit strategy are combined to improve the performance of this algorithm.Experiments on 11 representative instances show that QPCFA achieve new and better results on seven ones and matched the current best records on the other four.In addition,the calculation accuracy is improved considerably.%带平衡约束的圆形Packing问题是以卫星舱布局为背景的具有NP难度的布局优化问题.文中建立了此问题相应的数学模型,同时提出了两个新的物理模型,并受工艺加工过程中“粗精加工”现象的启发,提出了基于粗精调技术的拟物算法QPCFA.该算法既兼顾了搜索空间的多样性以利于全局搜索,又能对有前途的局部区域进行精细搜索以找到相应的局部最优解.同时,在计算过程中引入禁忌技术和跳坑策略,以提高算法的求解质量.对国际上11个代表性的算例进行了计算,QPCFA更新了其中7个算例的最好记录,其余4个与目前的最好记录基本持平,且与目前的最好结果相比在计算精度上均有较大的提高.

  13. Adhesive loose packings of small dry particles

    Science.gov (United States)

    Liu, Wenwei; Li, Shuiqing; Baule, Adrian; Makse, Hernán A.

    We explore adhesive loose packings of dry small spherical particles of micrometer size using 3D discrete-element simulations with adhesive contact mechanics. A dimensionless adhesion parameter ($Ad$) successfully combines the effects of particle velocities, sizes and the work of adhesion, identifying a universal regime of adhesive packings for $Ad>1$. The structural properties of the packings in this regime are well described by an ensemble approach based on a coarse-grained volume function that includes correlations between bulk and contact spheres. Our theoretical and numerical results predict: (i) An equation of state for adhesive loose packings that appears as a continuation from the frictionless random close packing (RCP) point in the jamming phase diagram; (ii) The existence of a maximal loose packing point at the coordination number $Z=2$ and packing fraction $\\phi=1/2^{3}$. Our results highlight that adhesion leads to a universal packing regime at packing fractions much smaller than the random loose packing, which can be described within a statistical mechanical framework. We present a general phase diagram of jammed matter comprising frictionless, frictional, adhesive as well as non-spherical particles, providing a classification of packings in terms of their continuation from the spherical frictionless RCP.

  14. Covering and packing pumpkin models

    OpenAIRE

    Chatzidimitriou, Dimitris; Raymond, Jean-Florent; Sau, Ignasi; Thilikos, Dimitrios M.

    2014-01-01

    International audience Let θr (the r-pumpkin) be the multi-graph containing two vertices and r parallel edges between them. We say that a graph is a a θr-model if it can be transformed into θr after a (possibly empty) sequence of contractions. We prove that there is a function g : N → N such that, for every two positive integers k and q, if G is a Kq-minor-free graph, then either G contains a set of k vertex-disjoint subgraphs (a θr-model-vertex-packing) each isomorphic to a θr-model or a ...

  15. Packing, tiling, orthogonality and completeness

    OpenAIRE

    Kolountzakis, Mihail N.

    1999-01-01

    Let $\\Omega \\subseteq {\\bf R}^d$ be an open set of measure 1. An open set $D \\subseteq {\\bf R}^d$ is called a ``tight orthogonal packing region'' for $\\Omega$ if $D-D$ does not intersect the zeros of the Fourier Transform of the indicator function of $\\Omega$ and $D$ has measure 1. Suppose that $\\Lambda$ is a discrete subset of ${\\bf R}^d$. The main contribution of this paper is a new way of proving the following result (proved by different methods by Lagarias, Reeds and Wang and, in the case...

  16. Method of immersion of a problem of comparison financial conditions of the enterprises in an expert cover in a class algorithms of artificial intelligence

    Directory of Open Access Journals (Sweden)

    S. V. Bukharin

    2016-01-01

    Full Text Available The financial condition of the enterprise can be estimated by a set of characteristics (solvency and liquidity, structure of the capital, profitability, etc.. The part of financial coefficients is low-informative, and other part contains the interconnected sizes. Therefore for elimination of ambiguity we will pass to the generalized indicators – rating numbers, and as the main means of research it is offered to use the theory of expert systems. As characteristic of the modern theory of expert systems it is necessary to consider application of intellectual ways of data processing of data mining, or simply data mining. The method of immersion of a problem of comparison of a financial condition of economic objects in an expert cover in a class of systems of artificial intelligence is offered (algorithms of a method of the analysis of hierarchies, contiguity leaning of a neural network, algorithm of training with function of activation softmax. The generalized indicator of structure of the capital in the form of rating number is entered and the sign (factorial space for seven concrete enterprises is created. Quantitative signs (financial coefficients of structure of the capital are allocated and their normalization by rules of the theory of expert systems is carried out. To the received set of the generalized indicators the method of the analysis of hierarchies is applied: on the basis of a linguistic scale of T. Saaty the ranks of signs reflecting the relative importance of various financial coefficients are defined and the matrix of pair comparisons is constructed. The vector of priority signs on the basis of the solution of the equation for own numbers and own vectors of the mentioned matrix is calculated. As a result the visualization of the received results which has allowed to eliminate difficulties of interpretation of small and negative values of the generalized indicator is carried out. The neural network with contiguity leaning and

  17. The “Theoreticals” Pack

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    The Particle Zoo is a colourful set of hand-made soft toys representing the particles in the Standard Model and beyond. It includes a “theoreticals” pack where you can find yet undiscovered particles: the best-selling Higgs boson, the graviton, the tachyon, and dark matter. Supersymmetric particle soft toys are also available on demand. But what would happen to the zoo if Nature had prepared some unexpected surprises? Julie Peasley, the zookeeper, is ready to sew new smiling faces…   The "Theoreticals" pack in the Particle Zoo. There is only one place in the world where you can buy a smiling Higgs boson and it’s not at CERN, although this is where scientists hope to observe it. The blue star-shaped particle is the best seller of Julie Peasley’s Particle Zoo – a collection of tens of soft toys representing all sorts of particles, including composite and decaying particles.  Over the years Julie’s zoo ...

  18. An Extended, Problem-Based Learning Laboratory Exercise on the Diagnosis of Infectious Diseases Suitable for Large Level 1 Undergraduate Biology Classes

    Science.gov (United States)

    Tatner, Mary; Tierney, Anne

    2016-01-01

    The development and evaluation of a two-week laboratory class, based on the diagnosis of human infectious diseases, is described. It can be easily scaled up or down, to suit class sizes from 50 to 600 and completed in a shorter time scale, and to different audiences as desired. Students employ a range of techniques to solve a real-life and…

  19. Simulated Annealing Algorithm and Its Application in Irregular Polygons Packing

    Institute of Scientific and Technical Information of China (English)

    段国林; 王彩红; 张健楠

    2003-01-01

    Two-dimensional irregular polygons packing problem is very difficult to be solved in traditional optimal way.Simulated annealing(SA)algorithm is a stochastic optimization technique that can be used to solve packing problems.The whole process of SA is introduced firstly in this paper. An extended neighborhood searching method in SA is mainly analyzed. A general module of SA algorithm is given and used to lay out the irregular polygons. The judgment of intersection and other constrains of irregular polygons are analyzed. Then an example that was used in the paper of Stefan Jakobs is listed.Results show that this SA algorithm shortens the computation time and improves the solution.

  20. Refurbishment of packed tubesheets utilizing plastic ferrules embedded in epoxy cladding

    Energy Technology Data Exchange (ETDEWEB)

    Spires, G.V. [Advanced Corrosion Engineering, Inc., Kingwood, TX (United States); Price, K.L. [Tampa Electric Company, Tampa, FL (United States)

    1996-08-01

    Retubing a Type 316 Stainless tubesheet of the packed tube joint design with more noble super austenitic stainless steel tubes prompted galvanic corrosion of the lead elements comprising the packing. Preventing such attack in a warm seawater cooled condenser was crucial to condensate quality. The fact that the tubes move with respect to the tubesheet greatly complicated the general plan to use an epoxy coating to isolate the tube/tubesheet joints from the cooling water. This paper describes the unique solution that was used to correct the packing deterioration problem. An epoxy tubesheet overlay was applied in a manner that accommodated tube translation. This was achieved by replacing the packing with high density polyethylene (HDPE) plastic ferrules molded with integral crevical knurls which formed a seal with the tube ODs. A single new fiber packing ring behind the plastic ferrule proved critical to the success of this concept. 5 refs., 6 figs.

  1. Structured packing: an opportunity for energy savings

    International Nuclear Information System (INIS)

    This work emphasizes the advantages about the use of structured packing. This type of packings allows by its geometry to reduce the processing time giving energy savings and throw down the production costs in several industries such as heavy water production plants, petrochemical industry and all industries involved with separation processes. There is a comparative results of energy consumption utilizing the structured vs. Raschig packings. (Author)

  2. Wolf Pack Algorithm for Unconstrained Global Optimization

    OpenAIRE

    Hu-Sheng Wu; Feng-Ming Zhang

    2014-01-01

    The wolf pack unites and cooperates closely to hunt for the prey in the Tibetan Plateau, which shows wonderful skills and amazing strategies. Inspired by their prey hunting behaviors and distribution mode, we abstracted three intelligent behaviors, scouting, calling, and besieging, and two intelligent rules, winner-take-all generation rule of lead wolf and stronger-survive renewing rule of wolf pack. Then we proposed a new heuristic swarm intelligent method, named wolf pack algorithm (WPA). E...

  3. Three techniques for obtaining algebraic circle packings

    OpenAIRE

    Louder, Larsen; Mishchenko, Andrey M.; Souto, Juan

    2014-01-01

    The main purpose of this article is to demonstrate three techniques for proving algebraicity statements about circle packings. We give proofs of three related theorems: (1) that every finite simple planar graph is the contact graph of a circle packing on the Riemann sphere, equivalently in the complex plane, all of whose tangency points, centers, and radii are algebraic, (2) that every flat conformal torus which admits a circle packing whose contact graph triangulates the torus has algebraic ...

  4. Designing Drill-in Fluids by Using Ideal Packing Technique

    Institute of Scientific and Technical Information of China (English)

    Feng Wenqiang; Yan Jienian

    2007-01-01

    Selecting bridging agents properly is a critical factor in designing non-damaging or low-damaging drill-in fluids.Historically,Abrams' rule has been used for this purpose.However,Abrams' rule only addresses the size of particle required to initiate a bridge.The rule does not give an optimum size nor an ideal packing sequence for minimizing fluid invasion and optimizing sealing.This paper elaborates an ideal packing approach to solving the sealing problem by sealing pores with different sizes,especially those large pores which usually make dominant contribution to permeability and thereby effectively preventing the solids and filtrate of drill-in fluids from invading into formations,compared with the conventionally used techniques.Practical software has been developed to optimize the blending proportion of several bridging agents,so as to achieve ideal packing effectiveness.The method and its use in selecting the best blending proportion of several bridging agents are also discussed in this paper.A carefully designed drill-in fluid by using the ideal packing technique (named the IPT fluid) for offshore drilling operations at the Weizhou Oilfield,Nanhai West Company,CNOOC is presented.The near 100% return permeabilities from the dynamic damage tests using reservoir cores demonstrated the excellent bridging effect provided by this drill-in fluid.

  5. Non standard pallet series designing problem in ammunition supply system

    Institute of Scientific and Technical Information of China (English)

    Li Liangchun; Guo Min; Wang Hongwei

    2005-01-01

    According to the compound packing problem in ammunition supply system in our army, the non-standard pallet series design model is proposed, and the original problem that can be solved as a set cover problem with a nested bin-packing problem, is analyzed, then two heuristic algorithms are applied to solve the problem.

  6. Minimally packed phases in holography

    CERN Document Server

    Donos, Aristomenis

    2015-01-01

    We numerically construct asymptotically AdS black brane solutions of $D=4$ Einstein-Maxwell theory coupled to a pseudoscalar. The solutions are holographically dual to $d=3$ CFTs held at constant chemical potential and magnetic field that spontaneously break translation invariance leading to the spontaneous formation of abelian and momentum magnetisation currents flowing around the plaquettes of a periodic Bravais lattice. We analyse the three-dimensional moduli space of lattice solutions, which are generically oblique, and show that the free energy is minimised by the triangular lattice, associated with minimal packing of circles in the plane. The triangular structure persists at low temperatures indicating the existence of novel crystalline ground states.

  7. Research on Models and Algorithms of Two-stage Combinatorial Bin Packing Problem of Vehicle Outbound Logistics%面向汽车整车出厂物流的两阶段组合装箱调度优化模型与算法研究

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    The paper studies a two-stage optimization of vehicle outbound logistics in consideration of orders,trucks,dock resources,customer requirements,and distribution costs.Firstly,the problem is divided into two stages.One is bin packing problem with constraints of loading,directions and combo transportation.The other is dock assignment problem with variant arrival time of trucks and unavailable periods of docks.Secondly,an integer linear programming is built.Thirdly,a branch and bound and a heuristic algorithm are further designed.Finally,the paper verifies the validity of the models and algorithms through computational experiments and comparison of practical cases with artificial scheduling results.It is proved that the models and algorithms are effective and efficient.%研究组合装箱与道位分配的两阶段出厂物流的调度模型与算法,问题将考虑订单、驳运车、仓库道位资源、客户需求、配送成本等多种因素.首先将所研究问题划分为带装箱约束、方向约束和拼车约束的组合装箱子问题,和带驳运车到达时间及道位不可用时间段的道位分配问题.针对两个子问题建混合线性整数模型并分别设计了分支定界和启发式算法,实现两阶段整合求解.最后,通过数值实验和与人工调度结果的对比模型,表明了模型和算法的有效性.

  8. A honeycomb-tube packing medium and its application to column flotation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Min; SHI Chang-sheng; LIU Jiong-tian; ZHAI Ai-feng

    2009-01-01

    We address problems in the development of large-scale flotation columns that use short cylinders. As a starting point, we investigated the packing medium to identify a highly efficient internal packing for the flotation column. The chosen packing was a honeycomb structure with an aperture diameter of 80 mm, a web thickness of 0.80 mm, a film height of 1000 mm, packed into a 400 mm diameter space, which completely filled the vessel at optimal cost. The column consisted of a modular ring of single-hole hexagonal honeycomb tube packing made from atactic polyproplene (PP-R). The packing was tested in a cyclonic, static mi-cro-bubble flotation column. Computational fluid dynamic modeling was used to analyze the flotation fluid in a honeycomb tube packed flotation column. Our results show that the fluid axial movement was maximized and that the transverse fluid velocities were zero in the vicinity of axial flow. Using the honeycomb tube packing for copper sulfide flotation we observed that the average concentration in the product was increased to 25.41%, from an average feed concentration of 0.729%, with an average recovery of 92.92%. The demands of on-site industrial production were met.

  9. Confined disordered strictly jammed binary sphere packings

    Science.gov (United States)

    Chen, D.; Torquato, S.

    2015-12-01

    Disordered jammed packings under confinement have received considerably less attention than their bulk counterparts and yet arise in a variety of practical situations. In this work, we study binary sphere packings that are confined between two parallel hard planes and generalize the Torquato-Jiao (TJ) sequential linear programming algorithm [Phys. Rev. E 82, 061302 (2010), 10.1103/PhysRevE.82.061302] to obtain putative maximally random jammed (MRJ) packings that are exactly isostatic with high fidelity over a large range of plane separation distances H , small to large sphere radius ratio α , and small sphere relative concentration x . We find that packing characteristics can be substantially different from their bulk analogs, which is due to what we term "confinement frustration." Rattlers in confined packings are generally more prevalent than those in their bulk counterparts. We observe that packing fraction, rattler fraction, and degree of disorder of MRJ packings generally increase with H , though exceptions exist. Discontinuities in the packing characteristics as H varies in the vicinity of certain values of H are due to associated discontinuous transitions between different jammed states. When the plane separation distance is on the order of two large-sphere diameters or less, the packings exhibit salient two-dimensional features; when the plane separation distance exceeds about 30 large-sphere diameters, the packings approach three-dimensional bulk packings. As the size contrast increases (as α decreases), the rattler fraction dramatically increases due to what we call "size-disparity" frustration. We find that at intermediate α and when x is about 0.5 (50-50 mixture), the disorder of packings is maximized, as measured by an order metric ψ that is based on the number density fluctuations in the direction perpendicular to the hard walls. We also apply the local volume-fraction variance στ2(R ) to characterize confined packings and find that these

  10. Dense packing of spheres around rods in supramolecular aggregates

    International Nuclear Information System (INIS)

    We consider a system of identically-sized spheres that coat a rod in a dense monolayer. We derive relationships that show how the number of spheres needed to cover a unit length of rod depends on the sphere and rod radii. The analysis could provide a stimulating exercise for students who have been introduced to the conventional examples of dense packing that are taught in many introductory physical science courses. The new class of liquid crystalline system which prompted this analysis may have applications in displays that can maintain stable liquid crystalline order over a broad range of temperatures. (author)

  11. Particle-size distribution and packing fraction of geometric random packings

    NARCIS (Netherlands)

    Brouwers, H.J.H.

    2006-01-01

    This paper addresses the geometric random packing and void fraction of polydisperse particles. It is demonstrated that the bimodal packing can be transformed into a continuous particle-size distribution of the power law type. It follows that a maximum packing fraction of particles is obtained when t

  12. Estimating the richness of a population when the maximum number of classes is fixed: a nonparametric solution to an archaeological problem.

    Directory of Open Access Journals (Sweden)

    Metin I Eren

    Full Text Available BACKGROUND: Estimating assemblage species or class richness from samples remains a challenging, but essential, goal. Though a variety of statistical tools for estimating species or class richness have been developed, they are all singly-bounded: assuming only a lower bound of species or classes. Nevertheless there are numerous situations, particularly in the cultural realm, where the maximum number of classes is fixed. For this reason, a new method is needed to estimate richness when both upper and lower bounds are known. METHODOLOGY/PRINCIPAL FINDINGS: Here, we introduce a new method for estimating class richness: doubly-bounded confidence intervals (both lower and upper bounds are known. We specifically illustrate our new method using the Chao1 estimator, rarefaction, and extrapolation, although any estimator of asymptotic richness can be used in our method. Using a case study of Clovis stone tools from the North American Lower Great Lakes region, we demonstrate that singly-bounded richness estimators can yield confidence intervals with upper bound estimates larger than the possible maximum number of classes, while our new method provides estimates that make empirical sense. CONCLUSIONS/SIGNIFICANCE: Application of the new method for constructing doubly-bound richness estimates of Clovis stone tools permitted conclusions to be drawn that were not otherwise possible with singly-bounded richness estimates, namely, that Lower Great Lakes Clovis Paleoindians utilized a settlement pattern that was probably more logistical in nature than residential. However, our new method is not limited to archaeological applications. It can be applied to any set of data for which there is a fixed maximum number of classes, whether that be site occupancy models, commercial products (e.g. athletic shoes, or census information (e.g. nationality, religion, age, race.

  13. A two-stage packing procedure for a Portuguese trading company

    OpenAIRE

    Moura, Ana; Bortfeldt, Andreas

    2010-01-01

    This case study deals with a two-stage packing problem that has to be solved in the daily distribution process of a Portuguese trading company. At the first stage boxes including goods are to be packed on pallets while at the second stage these pallets are loaded into one or more trucks. The boxes have to be transported to different customers and the actual goal is to guarantee a sufficient utilization of the truck loading spaces. A two-stage packing procedure is proposed to co...

  14. BIPP (BISMUTH IODINE PARAFFINE PASTE PACK REVISITED

    Directory of Open Access Journals (Sweden)

    Balasubramanian Thiagarajan

    2011-09-01

    Full Text Available This review article takes a new look at the use of BIPP pack following nasal and ear surgeries. It lists the advantages and pitfalls of using this packing material. Pubmed search revealed very little material on this topic hence I compiled existing data to bring out an article.

  15. Call packing bound for overflow loss systems

    NARCIS (Netherlands)

    N.M. van Dijk; E. van der Sluis

    2009-01-01

    Finite loss queues with overflow naturally arise in a variety of communications structures. For these systems, there is no simple analytic expression for the loss probability. This paper proves and promotes easily computable bounds based on the so-called call packing principle. Under call packing, a

  16. Call packing bounds for overflow queues

    NARCIS (Netherlands)

    N.M. van Dijk; E. van der Sluis

    2004-01-01

    Finite queueing loss systems are studied with overflow. For these systems there is no simple analytic expression for the loss probability or throughput. This paper aims to prove and promote easily computable bounds as based upon the so-called call packing principle. Under call packing a standard pro

  17. Difference packing arrays and systematic authentication codes

    Institute of Scientific and Technical Information of China (English)

    YIN Jianxing

    2004-01-01

    In this paper, a type of combinatorial design (called difference packing array)is proposed and used to give a construction of systematic authentication codes. Taking advantage of this construction, some new series of systematic authentication codes are obtainable in terms of existing difference packing arrays.

  18. Monitoring three-dimensional packings in microgravity.

    NARCIS (Netherlands)

    Yu, Peidong; Frank-Richter, Stefan; Börngen, Alexander; Sperl, Matthias

    2014-01-01

    We present results from experiments with granular packings in three dimensions in microgravity as realized on parabolic flights. Two different techniques are employed to monitor the inside of the packings during compaction: (1) X-ray radiography is used to measure in transmission the integrated fluc

  19. Pack Density Limitations of Hybrid Parachutes

    Science.gov (United States)

    Zwicker, Matthew L.; Sinclair, Robert J.

    2013-01-01

    The development and testing of the Orion crew capsule parachute system has provided a unique opportunity to study dense parachute packing techniques and limits, in order to establish a new baseline for future programs. The density of parachute packs has a significant influence on vibration loads, retention system stresses, and parachute mortar performance. Material compositions and pack densities of existing designs for space capsule recovery were compared, using the pack density of the Apollo main parachutes as the current baseline. The composition of parachutes has changed since Apollo, incorporating new materials such as Kevlar , Vectran , Teflon and Spectra . These materials have different specific densities than Nylon, so the densities of hybrid parachute packs cannot be directly compared to Nylon parachutes for determination of feasibility or volume allocation. Six parachute packs were evaluated in terms of weighted average solid density in order to achieve a non-dimensional comparison of packing density. Means of mitigating damage due to packing pressure and mortar firing were examined in light of the Capsule Parachute Assembly System (CPAS) and Apollo experience. Parachute design improvements including incorporation of modern materials and manufacturing processes serves to make CPAS the new knowledge base on which future spacecraft parachute systems will be built.

  20. Cluster and constraint analysis in tetrahedron packings.

    Science.gov (United States)

    Jin, Weiwei; Lu, Peng; Liu, Lufeng; Li, Shuixiang

    2015-04-01

    The disordered packings of tetrahedra often show no obvious macroscopic orientational or positional order for a wide range of packing densities, and it has been found that the local order in particle clusters is the main order form of tetrahedron packings. Therefore, a cluster analysis is carried out to investigate the local structures and properties of tetrahedron packings in this work. We obtain a cluster distribution of differently sized clusters, and peaks are observed at two special clusters, i.e., dimer and wagon wheel. We then calculate the amounts of dimers and wagon wheels, which are observed to have linear or approximate linear correlations with packing density. Following our previous work, the amount of particles participating in dimers is used as an order metric to evaluate the order degree of the hierarchical packing structure of tetrahedra, and an order map is consequently depicted. Furthermore, a constraint analysis is performed to determine the isostatic or hyperstatic region in the order map. We employ a Monte Carlo algorithm to test jamming and then suggest a new maximally random jammed packing of hard tetrahedra from the order map with a packing density of 0.6337.

  1. 7 CFR 51.1217 - Standard pack.

    Science.gov (United States)

    2010-01-01

    ... be ring faced and tightly packed with sufficient bulge to prevent any appreciable movement of the... the box. (d) Peaches packed in other type boxes such as wire-bound boxes and fiber-board boxes may be... than 10 percent of the packages in any lot may not meet these requirements. (i) “Well filled”...

  2. Prevalence of Salmonella spp. in Packed and Unpacked Red Meat and Chicken in South of Tehran

    OpenAIRE

    Soltan Dallal, Mohammad Mehdi; Sharifi Yazdi, Mohammad kazem; Nima MIRZAEI; kalantar, enayat

    2014-01-01

    Background: Despite of the advances in infectious diseases prevention and food technology, food-borne diseases are considered major problems in developed and developing countries. Meat plays a key role in transferring zoonotic diseases to human. Objectives: This study was conducted in south of Tehran, Iran, to investigate the prevalence rate of Salmonella spp. in packed and unpacked red meat and chicken. Materials and Methods: A total of 379 packed and unpacked samples including 189 red meat ...

  3. 高校班级管理工作存在的问题及对策%Problems and Countermeasures in Class Management in Colleges and Universities

    Institute of Scientific and Technical Information of China (English)

    陈悦; 刘畅; 佟明光

    2012-01-01

    班级管理是对班级所拥有的资源进行有效计划、组织、领导和控制的过程,是高校管理工作的辅助,是实现培养目标的重要手段和保证。班级管理工作的好坏直接反映了一个学校的管理水平和办学水平。%Class management is the process of effective planning, organization, leading and control of class resources, assistance to the college management and important means & guarantee for realization of student cultivation goal. The performance of class management reflects directly the management and education levels of a college.

  4. Models and algorithms for solving packing problems in logistics

    OpenAIRE

    Alonso Martínez, María Teresa

    2015-01-01

    El propósito de la tesis es contribuir a una solución eficiente a varios problemas de empaquetado que tienen las empresas de logística, en el proceso de enviar productos desde los centros de distribución hasta el cliente final. Las soluciones a estos problemas se alcanzan mediante modelos y algoritmos exactos cuando es posible o mediante metaheuristicos, los cuales no garantizan la optimalidad pero producen soluciones de calidad en un breve periodo de tiempo. Para ser más precisos los prob...

  5. An Improved Mond-Wier Type Dual for a Class of Multiobjective Control Problems with Generalized Invexity%一类广义凸多目标优化控制问题的改进的Mond-Weir型对偶

    Institute of Scientific and Technical Information of China (English)

    刘海军; 陈国庆

    2006-01-01

    利用向量泛函的不变凸性,改进了Mond-Weir型对偶,给出并证明了弱对偶定理和强对偶定理.%An improved Mond-Weir type dual for a class of multiobjective optimal control problems is constructed. Under vector functional invexity assumption, a number of weak and strong duality theorems are given and proved.

  6. Condensation in Nanoporous Packed Beds.

    Science.gov (United States)

    Ally, Javed; Molla, Shahnawaz; Mostowfi, Farshid

    2016-05-10

    In materials with tiny, nanometer-scale pores, liquid condensation is shifted from the bulk saturation pressure observed at larger scales. This effect is called capillary condensation and can block pores, which has major consequences in hydrocarbon production, as well as in fuel cells, catalysis, and powder adhesion. In this study, high pressure nanofluidic condensation studies are performed using propane and carbon dioxide in a colloidal crystal packed bed. Direct visualization allows the extent of condensation to be observed, as well as inference of the pore geometry from Bragg diffraction. We show experimentally that capillary condensation depends on pore geometry and wettability because these factors determine the shape of the menisci that coalesce when pore filling occurs, contrary to the typical assumption that all pore structures can be modeled as cylindrical and perfectly wetting. We also observe capillary condensation at higher pressures than has been done previously, which is important because many applications involving this phenomenon occur well above atmospheric pressure, and there is little, if any, experimental validation of capillary condensation at such pressures, particularly with direct visualization. PMID:27115446

  7. Hawking Colloquium Packed CERN Auditoriums

    CERN Multimedia

    2006-01-01

    Stephen Hawking's week long visit to CERN included an 'exceptional CERN colloquium' which filled six auditoriums. Stephen Hawking during his visit to the ATLAS experiment. Stephen Hawking, Lucasian Professor of Cambridge University, visited the Theory Unit of the Physics Department from 24 September to 1 October 2006. As part of his visit, he gave two lectures in the main auditorium - a theoretical seminar on 'The Semi-Classical Birth of The Universe', attended by about 120 specialists; and a colloquium titled 'The Origin of The Universe'. As a key public figure in theoretical physics, his presence was eagerly awaited on both occasions. Those who wanted to attend the colloquium had to arrive early and be equipped with plenty of patience. An hour before it was due to begin, the 400 capacity of the main auditorium was already full. The lecture, simultaneously broadcast to five other fully packed CERN auditoriums, was attended by an estimated total of 850. Stephen Hawking attracted a large CERN crowd, filling ...

  8. The fine triangle intersections for maximum kite packings

    OpenAIRE

    Zhang, Guizhi; Chang, Yanxun; Feng, Tao

    2012-01-01

    In this paper the fine triangle intersection problem for a pair of maximum kite packings is investigated. Let $Fin(v)={(s,t):$ $\\exists$ a pair of maximum kite packings of order $v$ intersecting in $s$ blocks and $s+t$ triangles$}$. Let $Adm(v)={(s,t): s+t\\leq b_v, s,t$ are non-negative integers$}$, where $b_v=\\lfloor v(v-1)/8\\rfloor$. It is established that $Fin(v)= Adm(v)\\setminus {(b_v-1,0),(b_v-1,1)}$ for any integer $v\\equiv 0,1 ({\\rm mod} 8)$ and $v\\geq 8$; $Fin(v)=Adm(v)$ for any integ...

  9. On the weak solution of a three-point boundary value problem for a class of parabolic equations with energy specification

    Directory of Open Access Journals (Sweden)

    Abdelfatah Bouziani

    2003-01-01

    Full Text Available This paper deals with weak solution in weighted Sobolev spaces, of three-point boundary value problems which combine Dirichlet and integral conditions, for linear and quasilinear parabolic equations in a domain with curved lateral boundaries. We, firstly, prove the existence, uniqueness, and continuous dependence of the solution for the linear equation. Next, analogous results are established for the quasilinear problem, using an iterative process based on results obtained for the linear problem.

  10. [Review: pathophysiology and methodology of nasal packing].

    Science.gov (United States)

    Beule, A G; Weber, R K; Kaftan, H; Hosemann, W

    2004-08-01

    Nasal packing is a frequent procedure to control spontaneous nasal bleeding or postoperative oozing following different types of nasal surgery. It strives for internal stabilization of the nasal framework and for optimizing wound healing by prevention of stenosis or synechia. A lot of different materials is used and there is no accepted standard concerning the type and application. A review on pathophysiology of the packed nose is given together with a survey on customary packing materials focussing on the specific merits, demerits and side-effects including economical aspects. PMID:15316896

  11. Improved Taxation Rate for Bin Packing Games

    Science.gov (United States)

    Kern, Walter; Qiu, Xian

    A cooperative bin packing game is a N-person game, where the player set N consists of k bins of capacity 1 each and n items of sizes a 1, ⋯ ,a n . The value of a coalition of players is defined to be the maximum total size of items in the coalition that can be packed into the bins of the coalition. We present an alternative proof for the non-emptiness of the 1/3-core for all bin packing games and show how to improve this bound ɛ= 1/3 (slightly). We conjecture that the true best possible value is ɛ= 1/7.

  12. Packing a Box with Bricks.

    Science.gov (United States)

    Jepsen, Charles H.

    1991-01-01

    Presented are solutions to variations of a combinatorics problem from a recent International Mathematics Olympiad. In particular, the matrix algebra solution illustrates an interaction among the undergraduate areas of geometry, combinatorics, linear algebra, and group theory. (JJK)

  13. An amino acid code to define a protein's tertiary packing surface.

    Science.gov (United States)

    Fraga, Keith J; Joo, Hyun; Tsai, Jerry

    2016-02-01

    One difficult aspect of the protein-folding problem is characterizing the nonspecific interactions that define packing in protein tertiary structure. To better understand tertiary structure, this work extends the knob-socket model by classifying the interactions of a single knob residue packed into a set of contiguous sockets, or a pocket made up of 4 or more residues. The knob-socket construct allows for a symbolic two-dimensional mapping of pockets. The two-dimensional mapping of pockets provides a simple method to investigate the variety of pocket shapes to understand the geometry of protein tertiary surfaces. The diversity of pocket geometries can be organized into groups of pockets that share a common core, which suggests that some interactions in pockets are ancillary to packing. Further analysis of pocket geometries displays a preferred configuration that is right-handed in α-helices and left-handed in β-sheets. The amino acid composition of pockets illustrates the importance of nonpolar amino acids in packing as well as position specificity. As expected, all pocket shapes prefer to pack with hydrophobic knobs; however, knobs are not selective for the pockets they pack. Investigating side-chain rotamer preferences for certain pocket shapes uncovers no strong correlations. These findings allow a simple vocabulary based on knobs and sockets to describe protein tertiary packing that supports improved analysis, design, and prediction of protein structure.

  14. Thirty five classes of solutions of the quantum time-dependent two-state problem in terms of the general Heun functions

    Science.gov (United States)

    Ishkhanyan, Artur M.; Shahverdyan, Tigran A.; Ishkhanyan, Tigran A.

    2015-01-01

    We derive 35 five-parametric classes of the quantum time-dependent two-state models solvable in terms of the general Heun functions. Each of the classes is defined by a pair of generating functions the first of which is referred to as the amplitude- and the second one as the detuning-modulation function. The classes suggest numerous families of specific field configurations with different physical properties generated by appropriate choices of the transformation of the independent variable, real or complex. There are many families of models with constant detuning or constant amplitude, numerous classes of chirped pulses of controllable amplitude and/or detuning, families of models with double or multiple (periodic) crossings, periodic amplitude modulation field configurations, etc. The detuning modulation function is the same for all the derived classes. This function involves four arbitrary parameters, that is, two more than the previously known hypergeometric classes. These parameters in general are complex and should be chosen so that the resultant detuning is real for the applied (arbitrary) complex-valued transformation of the independent variable. The generalization of the detuning modulation function to the four-parametric case is the most notable extension since many useful properties of the two-state models described by the Heun equation are due to namely the additional parameters involved in this function. Many of the derived amplitude modulation functions present different generalizations of the known hypergeometric models. In several cases the generalization is achieved by multiplying the amplitude modulation function of the corresponding prototype hypergeometric class by an extra factor including an additional parameter. Finally, many classes suggest amplitude modulation functions having forms not discussed before. We present several families of constant-detuning field configurations generated by a real transformation of the independent variable. The

  15. Discipline Problems in The EFL Class: Is There a Cure? Problemas con la disciplina en el aula de inglés: ¿Existe una cura?

    Directory of Open Access Journals (Sweden)

    Doris de Almeida Soares

    2007-12-01

    Full Text Available This article discusses the findings of an action research project carried out to minimize the negative class participation of 10 EFL pre-intermediate students, aged-11-14, in a language school in Rio de Janeiro, Brazil. First, some theoretical issues concerning discipline in the language class will be discussed. Second, the original project I developed in 1995 to minimize the negative class participation of 14 EFL beginner students, aged 1 -15, will be reviewed. Next, the experiment with the 003 group will be described. The results seem to confirm that, although some adaptations to the original project were necessary, when students reflect upon their importance in the lessons, they tend to behave better in class and to show a more positive attitude towards learning.Este artículo discute los resultados de una investigación acción realizada para minimizar los problemas de disciplina en una clase de 10 alumnos de inglés, de nivel pre-intermedio, con edades entre 11-14 años, en un instituto de Rio de Janeiro, Brasil. En primer lugar, se discuten algunos presupuestos teóricos; en segundo lugar, presento el proyecto original que desarrollé en 1995 para trabajar con la indisciplina en mi clase de 14 alumnos principiantes en inglés, con edad entre 1 -15 años. A continuación, se describe el experimento realizado con el grupo de 003. Los resultados parecen confirmar que, aunque fueron necesarias algunas adaptaciones al proyecto inicial, cuando los alumnos reflexionan sobre su importancia para las clases, tienden a portarse mejor y demuestran una actitud más positiva hacia el aprendizaje.

  16. Electroosmotic Driving Liquid Using Nanosilica Packed Column

    Institute of Scientific and Technical Information of China (English)

    Ling Xin CHEN; Guo An LUO; Tao WEN

    2005-01-01

    The electroosmotic pump (EOP) using nanosilica particles packed-bed column was experimentally studied. The relationship between flowrate, pressure and applied voltage of the pump, and pressure-flowrate (P-Q) characteristic were investigated.

  17. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander

    2009-01-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry. © 2009 ACM.

  18. Think Safety When Picking, Packing School Backpacks

    Science.gov (United States)

    ... 160523.html Think Safety When Picking, Packing School Backpacks Heavy, unbalanced loads can cause injury that is ... Aug. 19, 2016 (HealthDay News) -- Many students use backpacks to carry their school books and supplies, but ...

  19. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander

    2009-12-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry.

  20. Protein Packing Quality Using Delaunay Complexes

    DEFF Research Database (Denmark)

    Fonseca, Rasmus; Winter, Pawel; Karplus, Kevin

    2011-01-01

    A new method for estimating the packing quality of protein structures is presented. Atoms in high quality protein crystal structures are very uniformly distributed which is difficult to reproduce using structure prediction methods. Packing quality measures can therefore be used to assess structur...... respectively. Our results show that the developed method is correlated to the well-established RosettaHoles2 but three times faster....

  1. Patchy particle packing under electric fields.

    Science.gov (United States)

    Song, Pengcheng; Wang, Yufeng; Wang, Yu; Hollingsworth, Andrew D; Weck, Marcus; Pine, David J; Ward, Michael D

    2015-03-01

    Colloidal particles equipped with two, three, or four negatively charged patches, which endow the particles with 2-fold, 3-fold, or tetrahedral symmetries, form 1D chains, 2D layers, and 3D packings when polarized by an AC electric field. Two-patch particles, with two patches on opposite sides of the particle (2-fold symmetry) pack into the cmm plane group and 3D packings with I4mm space group symmetry, in contrast to uncharged spherical or ellipsoidal colloids that typically crystallize into a face-centered ABC layer packing. Three-patch particles (3-fold symmetry) form chains having a 21 screw axis symmetry, but these chains pair in a manner such that each individual chain has one-fold symmetry but the pair has 21 screw axis symmetry, in an arrangement that aligns the patches that would favor Coulombic interactions along the chain. Surprisingly, some chain pairs form unanticipated double-helix regions that result from mutual twisting of the chains about each other, illustrating a kind of polymorphism that may be associated with nucleation from short chain pairs. Larger 2D domains of the three-patch particles crystallize in the p6m plane group with alignment (with respect to the field) and packing densities that suggest random disorder in the domains, whereas four-patch particles form 2D domains in which close-packed rows are aligned with the field.

  2. iTreePack: Protein Complex Side-Chain Packing by Dual Decomposition

    OpenAIRE

    Peng, Jian; Hosur, Raghavendra; Berger, Bonnie; Xu, Jinbo

    2015-01-01

    Protein side-chain packing is a critical component in obtaining the 3D coordinates of a structure and drug discovery. Single-domain protein side-chain packing has been thoroughly studied. A major challenge in generalizing these methods to protein complexes is that they, unlike monomers, often have very large treewidth, and thus algorithms such as TreePack cannot be directly applied. To address this issue, SCWRL4 treats the complex effectively as a monomer, heuristically excluding weak interac...

  3. Genetic algorithm for short-term scheduling of make-and-pack batch production process

    Institute of Scientific and Technical Information of China (English)

    Wuthichai Wongthatsanekorn; Busaba Phruksaphanrat

    2015-01-01

    This paper considers a scheduling problem in industrial make-and-pack batch production process. This process equips with sequence-dependent changeover time, multipurpose storage units with limited capacity, storage time, batch splitting, partial equipment connectivity and transfer time. The objective is to make a production plan to satisfy al constraints while meeting demand requirement of packed products from various product fam-ilies. This problem is NP-hard and the problem size is exponentially large for a realistic-sized problem. Therefore, we propose a genetic algorithm to handle this problem. Solutions to the problems are represented by chromo-somes of product family sequences. These sequences are decoded to assign the resource for producing packed products according to forward assignment strategy and resource selection rules. These techniques greatly reduce unnecessary search space and improve search speed. In addition, design of experiment is carefully utilized to de-termine appropriate parameter settings. Ant colony optimization and Tabu search are also implemented for com-parison. At the end of each heuristics, local search is applied for the packed product sequence to improve makespan. In an experimental analysis, al heuristics show the capability to solve large instances within reason-able computational time. In al problem instances, genetic algorithm averagely outperforms ant colony optimiza-tion and Tabu search with slightly longer computational time.

  4. Snow Pack and Lake Ice Pack Remote Sensing using Wideband Autocorrelation Radiometry

    Science.gov (United States)

    Mousavi, S.; De Roo, R. D.; Sarabandi, K.; England, A. W.

    2015-12-01

    A novel microwave radiometric technique, wideband autocorrelation radiometry (WiBAR), offers a deterministic method of remotely sensing the propagation time τdelay of microwaves through low loss layers at the bottom of the atmosphere. Terrestrial examples are the snow and lake ice packs. This technique is based on the Planck radiation from the surface beneath the pack which travels upwards through the pack towards the radiometer; such a signal we call a direct signal. On the other hand, part of this radiation reflects back from the pack's upper interface then from its lower interface, before traveling towards the radiometer's antenna. Thus, there are two signals received by the radiometer, the direct signal and a delayed copy of it. The microwave propagation time τdelay through the pack yields a measure of its vertical extent. We report a time series of measurements of the ice pack on Lake Superior from February to April 2014 to demonstrate this technique. The observations are done at frequencies from 7 to 10 GHz. At these frequencies, the volume and surface scattering are small in the ice pack. This technique is inherently low-power since there is no transmitter as opposed to active remote sensing techniques. The results of this paper is to present the WiBAR technique and show that the microwave travel time within a dry snow pack and lake ice pack can be deterministically measured for different thicknesses using this technique.

  5. Tile-Packing Tomography Is NP-hard

    DEFF Research Database (Denmark)

    Chrobak, Marek; Dürr, Christoph; Guíñez, Flavio;

    2010-01-01

    Discrete tomography deals with reconstructing finite spatial objects from their projections. The objects we study in this paper are called tilings or tile-packings, and they consist of a number of disjoint copies of a fixed tile, where a tile is defined as a connected set of grid points. A row...... (its width or height is 1), while for some other types of tiles \\mathbbNPNP -hardness results have been shown in the literature. In this paper we present a complete solution to this question by showing that the problem remains \\mathbbNPNP -hard for all tiles other than bars....

  6. Effects of Problem-Based Learning Model versus Expository Model and Motivation to Achieve for Student's Physic Learning Result of Senior High School at Class XI

    Science.gov (United States)

    Prayekti

    2016-01-01

    "Problem-based learning" (PBL) is one of an innovative learning model which can provide an active learning to student, include the motivation to achieve showed by student when the learning is in progress. This research is aimed to know: (1) differences of physic learning result for student group which taught by PBL versus expository…

  7. 27 CFR 24.308 - Bottled or packed wine record.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottled or packed wine... BUREAU, DEPARTMENT OF THE TREASURY LIQUORS WINE Records and Reports § 24.308 Bottled or packed wine record. A proprietor who bottles, packs, or receives bottled or packed beverage wine in bond...

  8. Efficient linear programming algorithm to generate the densest lattice sphere packings.

    Science.gov (United States)

    Marcotte, Étienne; Torquato, Salvatore

    2013-06-01

    Finding the densest sphere packing in d-dimensional Euclidean space R(d) is an outstanding fundamental problem with relevance in many fields, including the ground states of molecular systems, colloidal crystal structures, coding theory, discrete geometry, number theory, and biological systems. Numerically generating the densest sphere packings becomes very challenging in high dimensions due to an exponentially increasing number of possible sphere contacts and sphere configurations, even for the restricted problem of finding the densest lattice sphere packings. In this paper we apply the Torquato-Jiao packing algorithm, which is a method based on solving a sequence of linear programs, to robustly reproduce the densest known lattice sphere packings for dimensions 2 through 19. We show that the TJ algorithm is appreciably more efficient at solving these problems than previously published methods. Indeed, in some dimensions, the former procedure can be as much as three orders of magnitude faster at finding the optimal solutions than earlier ones. We also study the suboptimal local density-maxima solutions (inherent structures or "extreme" lattices) to gain insight about the nature of the topography of the "density" landscape.

  9. Quasistatic packings of droplets in flat microfluidic channels

    Science.gov (United States)

    Kadivar, Erfan

    2016-02-01

    As observed in recent experiments, monodisperse droplets self-assemble spontaneously in different ordered packings. In this work, we present a numerical study of the droplet packings in the flat rectangular microfluidic channels. Employing the boundary element method, we numerically solve the Stokes equation in two-dimension and investigate the appearance of droplet packing and transition between one and two-row packings of monodisperse emulsion droplets. By calculating packing force applied on the droplet interface, we investigate the effect of flow rate, droplet size, and surface tension on the packing configurations of droplets and transition between different topological packings.

  10. A review on packed bed solar energy storage systems

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Harmeet; Saini, R.P. [Alternate Hydro Energy Centre, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Saini, J.S. [Mechanical and Industrial Engineering Department, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2010-04-15

    Because of intermittent nature of solar energy, storage is required for uninterrupted supply in order to match the needs. Packed beds are generally used for storage of thermal energy from solar air heaters. A packed bed is a volume of porus media obtained by packing particles of selected material into a container. A number of studies carried out on packed beds for their performance analysis were reported in the literature. These studies included the design of packed beds, materials used for storage, heat transfer enhancement, flow phenomenon and pressure drop through packed beds. This paper presents an extensive review on the research carried out on packed beds. Based on the literature review, it is concluded that most of the studies carried out are on rocks and pebbles as packing material. A very few studies were conducted on large sized packing materials. Further no study has been reported so far on medium sized storage elements in packed beds. (author)

  11. [Research progress on the management of no packing after septoplasty].

    Science.gov (United States)

    Lu, Sheng; Zhang, Longcheng; Li, Jieen

    2016-01-01

    Packing the nose after septoplasty is common practice. The use of postoperative packing has been proposed to reduce the dead space between the subperichondrial flaps and minimize postoperative complications such as hemorrhage, septal hematoma, and formation of synechiae. Additionally, postoperative packing is thought to stabilize the remaining cartilaginous septum and minimize persistence or recurrence of septal deviation. Despite these theoretic advantages, evidence to support the use of postoperative packing is lacking. Additionally, nasal packing is not an innocuous procedure. The use of nasal packing actually cause these complications such as postop- erative pain, mucosal injury, bleeding, worsening of breathing due to sleep disorders, and postoperative infections. Routine use of anterior nasal packing after septoplasty should be challenged for not presenting proven benefit. As alternatives to traditional packing, septal suturing, septal stapler and fibrin glue have been used recently. The purpose of this article is to summarize the progress of traditional packing to no packing after septoplasty. PMID:27197467

  12. Packing mode and optimization of flotation column

    Energy Technology Data Exchange (ETDEWEB)

    Li Yan-feng; Zhang Min; Liu Jiong-tian [University of Mining and Technology, Xuzhou (China). School of Chemical Engineering and Technology

    2008-04-15

    The effects of the two usual packing types, namely filling material and sieve plates, on flotation environment were analyzed and it was pointed out that sieve plate filling could be integrated with the fluid regime and mineralization environment with the results of stabilizing bubbles and enhancing the efficiencies of flotation and mineralization. The tests show that the ash gradient of the flotation column increases from 1.62%/m to 6.80%/m as a result of sieve plate filling. Material filling can clean the froth, reduce the ash of clean coal and make the froth steady. To form the two non-linear-change separation environments suitable for mineral separation, the mixed filling mode of packing sieve plates in the middle and lower parts of the column and packing material in the foam area was proposed. By optimizing the packing mode, the mixed packing mode of the sieve plates and honeycomb tubes were introduced. The simulation results show that obligatory suppression of the honeycomb tubes make the radial distribution of the fluid at the second sieve plate completely disappear and the axial velocity stable. It makes the flow regime transfers from turbulent flow to plug flow in a short distance come true. 7 refs., 5 figs., 2 tabs.

  13. Coalescence preference in dense packing of bubbles

    Science.gov (United States)

    Kim, Yeseul; Gim, Bopil; Gim, Bopil; Weon, Byung Mook

    2015-11-01

    Coalescence preference is the tendency that a merged bubble from the contact of two original bubbles (parent) tends to be near to the bigger parent. Here, we show that the coalescence preference can be blocked by densely packing of neighbor bubbles. We use high-speed high-resolution X-ray microscopy to clearly visualize individual coalescence phenomenon which occurs in micro scale seconds and inside dense packing of microbubbles with a local packing fraction of ~40%. Previous theory and experimental evidence predict a power of -5 between the relative coalescence position and the parent size. However, our new observation for coalescence preference in densely packed microbubbles shows a different power of -2. We believe that this result may be important to understand coalescence dynamics in dense packing of soft matter. This work (NRF-2013R1A22A04008115) was supported by Mid-career Researcher Program through NRF grant funded by the MEST and also was supported by Ministry of Science, ICT and Future Planning (2009-0082580) and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry and Education, Science and Technology (NRF-2012R1A6A3A04039257).

  14. A Class of Bridges of Iterated Integrals of Brownian Motion Related to Various Boundary Value Problems Involving the One-Dimensional Polyharmonic Operator

    Directory of Open Access Journals (Sweden)

    Aimé Lachal

    2011-01-01

    Full Text Available Let ((∈[0,1] be the linear Brownian motion and ((∈[0,1] the (−1-fold integral of Brownian motion, with being a positive integer: ∫(=0((−−1/(−1!d( for any ∈[0,1]. In this paper we construct several bridges between times 0 and 1 of the process ((∈[0,1] involving conditions on the successive derivatives of at times 0 and 1. For this family of bridges, we make a correspondence with certain boundary value problems related to the one-dimensional polyharmonic operator. We also study the classical problem of prediction. Our results involve various Hermite interpolation polynomials.

  15. Nasal packing aspiration in a patient with Alzheimer’s disease: a rare complication

    Directory of Open Access Journals (Sweden)

    Papadakis I

    2012-07-01

    Full Text Available Eleftherios Koudounarakis, Nikolaos Chatzakis, Ioannis Papadakis, Irene Panagiotaki, George VelegrakisDepartment of Otorhinolaryngology, University Hospital of Heraklion, Crete, GreeceAbstract: Nasal bleeding is a frequent problem for patients receiving anticoagulant agents. Most cases are successfully managed with anterior or posterior nasal packing. However, the complications of nasal packing should be always considered. We report the case of a 78-year-old man with Alzheimer’s disease who was treated for anterior epistaxis with anterior nasal packing using three pieces of antibiotic-soaked gauze. Two days later, the patient was admitted to the emergency department in respiratory distress. A chest x-ray demonstrated atelectasis of the right lung. During an examination of the nasal cavities, the nasal packing was removed, and one of the gauze pieces was missing. The patient underwent rigid bronchoscopy, and the missing gauze was found to be obstructing the right main bronchus. The patient’s respiratory function improved considerably after removal of the foreign body. It is assumed that gauze packs should be used with caution in patients with an impaired level of consciousness and neurodegenerative diseases.Keywords: epistaxis, nasal packing, aspiration, Alzheimer’s disease, cough reflex

  16. Substituted Septithiophenes with End Groups of Different Size: Packing and Frustration in Bulk and Thin Films.

    Science.gov (United States)

    de Jeu, Wim H; Rahimi, Khosrow; Ziener, Ulrich; Vill, Roman; Herzig, Eva M; Müller-Buschbaum, Peter; Möller, Martin; Mourran, Ahmed

    2016-02-16

    We report on three different liquid crystalline compounds with a central septithiophene core and alkylated end groups of strongly increasing bulkiness. In principle, the thiophene cores prefer to pack parallel to optimize their π-π interactions, which becomes sterically impossible for the bulkier end groups. Using X-ray diffraction, we find that the way out of this packing dilemma is toward liquid-crystal phases of higher dimensionality in the order smectic → columnar ↔ bicontinuous cubic. For the smectic phase, packing in a monolayer is no problem; for the other ones packing considerations become more stringent in films due to the boundaries. Surface X-ray techniques and atomic force microscopy indicate an appreciable difference between monolayer and three-layer films, in which the monolayers appear to escape from packing frustration by generating superstructures. We propose a basic structure of columns parallel to the substrate that provides a compromise between preserving some π-π interactions and packing the bulky alkyl groups. PMID:26807677

  17. 求解一类 Riccati - Bessel 方程边值问题的新方法%A New Method of Solving the Boundary Value Problem of a Class of Riccati - Bessel Equation

    Institute of Scientific and Technical Information of China (English)

    王强; 李顺初; 蒲俊

    2015-01-01

    This paper solved a boundary value problem of Riccati - Bessel equation;and the similar kernel function and similar structure of the solution were obtained. By further analysis and solving this class of boundary value problem,the guiding functions were firstly constructed by using two linearly independent solutions of Riccati- Bessel equation,and then the similar kernel function was assembled by the guiding functions and coefficient of right boundary value condition. The solution to the boundary value problem was assembled by similar kernel func-tion and coefficient of left boundary value condition. Therefore a new idea is put forward for solving this class of boundary value problem of Riccati - Bessel equation:similar structure.%针对 Riccati - Bessel 方程一类边值问题进行求解,获得了解式的相似核函数和相似结构,通过进一步分析,发现求解该类边值问题可先利用 Riccati - Bessel 方程的两个线性无关解构造引解函数,再结合右边值条件的系数组装得到相似核函数;通过相似核函数和左边值条件的系数组装就可以得到 Riccati - Bessel 方程边值问题的解,由此提出了解决该类 Riccati - Bessel 方程边值问题的一种新思路———相似构造。

  18. Overview about the Problems and Strategies of Large Class Teaching in American Universities%美国高校大班教学的常见问题与对策综述

    Institute of Scientific and Technical Information of China (English)

    周磊

    2014-01-01

    高校大班教学学生人数的大幅增加为教师教学工作的开展提出了难题。美国高校教师从以学生为中心的教学理念出发,在实践中探索出了一系列针对大班教学的教学策略。本文将从学生考勤、作业的布置与检查、教学方法与学生意见反馈等方面加以综述。%The increasing scale of students in large class teaching causes some serious problems for teachers. Based on the "stu-dent-centered"concept, college teachers in America have found a series of strategies targeting on large class teaching by practice. The paper makes a summary about how to deal with large class including attendance-checking, assignment, teaching methods and feedback,etc.

  19. 普通高校体育课堂管理学生问题行为研究%Research on the Management of Student Problems Behavior in PE Class of Ordinary Universities

    Institute of Scientific and Technical Information of China (English)

    臧彤

    2012-01-01

    Using paper documents, questionnaire survey, expert interviews, statistics, logical analysis and so on methods to understand the class Management situation of ordinary universities, the results showed that: student problem behavior could be divided into antagonistic behavior, disruptive behavior, inconspicuous behavior, blindly rebellious behavior, resist the behavior, etc. Main classroom Management strategies remained in class direct criticism, mildly criticized in class and after- school education.%采用文献资料法、问卷调查法、专家访谈法、数理统计法等研究方法了解山东省普通高校教师课堂管理现状,研究结果显示:学生问题行为主要可分为对抗性行为、扰乱秩序行为、惹人注意行为、盲目逆反行为、抗拒行为等。大部分的课堂管理策略基本保持在课上直接批评、课上婉转批评和课后教育方面。

  20. Packing of ganglioside-phospholipid monolayers

    DEFF Research Database (Denmark)

    Majewski, J.; Kuhl, T.L.; Kjær, K.;

    2001-01-01

    Using synchrotron grazing-incidence x-ray diffraction (GIXD) and reflectivity, the in-plane and out-of-plane structure of mixed ganglioside-phospholipid monolayers was investigated at the air-water interface. Mixed monolayers of 0, 5, 10, 20, and 100 mol% ganglioside GM, and the phospholipid dipa...... polymer groups. Indeed, the lack of packing disruptions by the oligosaccharide groups indicates that protein-GM, interactions, including binding, insertion, chain fluidization, and domain formation (lipid rafts), can be studied in 2-D monolayers using scattering techniques....... monolayers did not affect hydrocarbon tail packing (fluidization or condensation of the hydrocarbon region). This is in contrast to previous investigations of lipopolymer-lipid mixtures, where the packing structure of phospholipid monolayers was greatly altered by the inclusion of lipids bearing hydrophilic...

  1. Simulating the pervasive fracture and fragmentation of materials and structures using randomly close-packed Voronoi tessellations.

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, Joseph E.

    2008-09-01

    Under extreme loading conditions most often the extent of material and structural fracture is pervasive in the sense that a multitude of cracks are nucleating, propagating in arbitrary directions, coalescing, and branching. Pervasive fracture is a highly nonlinear process involving complex material constitutive behavior, material softening, localization, surface generation, and ubiquitous contact. Two primary applications in which pervasive fracture is encountered are (1) weapons effects on structures and (2) geomechanics of highly jointed and faulted reservoirs. A pure Lagrangian computational method based on randomly close-packed Voronoi tessellations is proposed as a rational approach for simulating the pervasive fracture of materials and structures. Each Voronoi cell is formulated as a finite element using the reproducing kernel method. Fracture surfaces are allowed to nucleate only at the intercell faces. The randomly seeded Voronoi cells provide an unbiased network for representing cracks. In this initial study two approaches for allowing the new surfaces to initiate are studied: (1) dynamic mesh connectivity and the instantaneous insertion of a cohesive traction when localization is detected, and (2) a discontinuous Galerkin approach in which the interelement tractions are an integral part of the variational formulation, but only become active once localization is detected. Pervasive fracture problems are extremely sensitive to initial conditions and system parameters. Dynamic problems exhibit a form of transient chaos. The primary numerical challenge for this class of problems is the demonstration of model objectivity and, in particular, the identification and demonstration of a measure of convergence for engineering quantities of interest.

  2. Characterization of maximally random jammed sphere packings. II. Correlation functions and density fluctuations

    Science.gov (United States)

    Klatt, Michael A.; Torquato, Salvatore

    2016-08-01

    In the first paper of this series, we introduced Voronoi correlation functions to characterize the structure of maximally random jammed (MRJ) sphere packings across length scales. In the present paper, we determine a variety of different correlation functions that arise in rigorous expressions for the effective physical properties of MRJ sphere packings and compare them to the corresponding statistical descriptors for overlapping spheres and equilibrium hard-sphere systems. Such structural descriptors arise in rigorous bounds and formulas for effective transport properties, diffusion and reactions constants, elastic moduli, and electromagnetic characteristics. First, we calculate the two-point, surface-void, and surface-surface correlation functions, for which we derive explicit analytical formulas for finite hard-sphere packings. We show analytically how the contact Dirac delta function contribution to the pair correlation function g2(r ) for MRJ packings translates into distinct functional behaviors of these two-point correlation functions that do not arise in the other two models examined here. Then we show how the spectral density distinguishes the MRJ packings from the other disordered systems in that the spectral density vanishes in the limit of infinite wavelengths; i.e., these packings are hyperuniform, which means that density fluctuations on large length scales are anomalously suppressed. Moreover, for all model systems, we study and compute exclusion probabilities and pore size distributions, as well as local density fluctuations. We conjecture that for general disordered hard-sphere packings, a central limit theorem holds for the number of points within an spherical observation window. Our analysis links problems of interest in material science, chemistry, physics, and mathematics. In the third paper of this series, we will evaluate bounds and estimates of a host of different physical properties of the MRJ sphere packings that are based on the

  3. Characterization of maximally random jammed sphere packings. II. Correlation functions and density fluctuations.

    Science.gov (United States)

    Klatt, Michael A; Torquato, Salvatore

    2016-08-01

    In the first paper of this series, we introduced Voronoi correlation functions to characterize the structure of maximally random jammed (MRJ) sphere packings across length scales. In the present paper, we determine a variety of different correlation functions that arise in rigorous expressions for the effective physical properties of MRJ sphere packings and compare them to the corresponding statistical descriptors for overlapping spheres and equilibrium hard-sphere systems. Such structural descriptors arise in rigorous bounds and formulas for effective transport properties, diffusion and reactions constants, elastic moduli, and electromagnetic characteristics. First, we calculate the two-point, surface-void, and surface-surface correlation functions, for which we derive explicit analytical formulas for finite hard-sphere packings. We show analytically how the contact Dirac delta function contribution to the pair correlation function g_{2}(r) for MRJ packings translates into distinct functional behaviors of these two-point correlation functions that do not arise in the other two models examined here. Then we show how the spectral density distinguishes the MRJ packings from the other disordered systems in that the spectral density vanishes in the limit of infinite wavelengths; i.e., these packings are hyperuniform, which means that density fluctuations on large length scales are anomalously suppressed. Moreover, for all model systems, we study and compute exclusion probabilities and pore size distributions, as well as local density fluctuations. We conjecture that for general disordered hard-sphere packings, a central limit theorem holds for the number of points within an spherical observation window. Our analysis links problems of interest in material science, chemistry, physics, and mathematics. In the third paper of this series, we will evaluate bounds and estimates of a host of different physical properties of the MRJ sphere packings that are based on the

  4. On generalized entropy solutions of the Cauchy problem for a first-order quasilinear equation in the class of locally summable functions

    Energy Technology Data Exchange (ETDEWEB)

    Panov, E Yu [Novgorod State University, Novgorod (Russian Federation)

    2002-12-31

    We construct a theory of locally summable generalized entropy solutions (g.e. solutions) of the Cauchy problem for a first-order non-homogeneous quasilinear equation with continuous flux vector satisfying a linear restriction on its growth. We prove the existence of greatest and least g.e. solutions, suggest sufficient conditions for uniqueness of g.e. solutions, prove several versions of the comparison principle, and obtain estimates for the L{sup p}-norms of solution with respect to the space variables. We establish the uniqueness of g.e. solutions in the case when the input data are periodic functions of the space variables.

  5. 大学英语听说课自主学习的现状与对策%The Problems and Suggestions of the Autonomy Learning in the Listening and Speaking Class of College English

    Institute of Scientific and Technical Information of China (English)

    向云

    2015-01-01

    近年来,大学英语听说课在网络环境下进行了全新的教学模式变革,其信息化、个性化、自主化的学习平台得到了广大师生的赞评,但在教学实践过程中也凸显出不少问题。本文在分析和探讨相关问题的基础上提出关于大学英语听说课教学的几点建议。%Nowadays, the listening and speaking class of college English has been reformed in the teaching mode based on Internet circumstances. This total new mode with its large amounts of information, individual and autonomous feature is popular among teachers and students. But there exists several problems in teaching practice. Therefore, the author makes suggestions on the teach⁃ing practice of listening and speaking class by analyzing and discussing their problems.

  6. On the Multiple Packing Densities of Triangles

    OpenAIRE

    Sriamorn, Kirati

    2014-01-01

    Given a convex disk $K$ and a positive integer $k$, let $\\delta_T^k(K)$ and $\\delta_L^k(K)$ denote the $k$-fold translative packing density and the $k$-fold lattice packing density of $K$, respectively. Let $T$ be a triangle. In a very recent paper, K. Sriamorn proved that $\\delta_L^k(T)=\\frac{2k^2}{2k+1}$. In this paper, I will show that $\\delta_T^k(T)=\\delta_L^k(T)$.

  7. Lattice approaches to packed column simulations

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This work presents a review of the findings into the ability of a digitally based particle packing algorithm, called DigiPac, to predict bed structure in a variety of packed columns, for a range of generic pellet shapes frequently used in the chemical and process engineering industries.Resulting macroscopic properties are compared with experimental data derived from both invasive and non-destructive measurement techniques.Additionally, fluid velocity distributions, through samples of the resulting bed structures, are analysed using lattice Boltzmann method (LBM) simulations and are compared against experimental data from the literature.

  8. Correlation between Voronoi volumes in disc packings

    OpenAIRE

    Zhao, Song-Chuan; Sidle, Stacy; Swinney, Harry L.; Schröter, Matthias

    2011-01-01

    We measure the two-point correlation of free Voronoi volumes in binary disc packings, where the packing fraction $\\phi_{\\rm avg}$ ranges from 0.8175 to 0.8380. We observe short-ranged correlations over the whole range of $\\phi_{\\rm avg}$ and anti-correlations for $\\phi_{\\rm avg}>0.8277$. The spatial extent of the anti-correlation increases with $\\phi_{\\rm avg}$ while the position of the maximum of the anti-correlation and the extent of the positive correlation shrink with $\\phi_{\\rm avg}$. We...

  9. Submaximal Riemann-Roch expected curves and symplectic packing.

    Directory of Open Access Journals (Sweden)

    Wioletta Syzdek

    2007-06-01

    Full Text Available We study Riemann-Roch expected curves on $mathbb{P}^1 imes mathbb{P}^1$ in the context of the Nagata-Biran conjecture. This conjecture predicts that for sufficiently large number of points multiple points Seshadri constants of an ample line bundle on algebraic surface are maximal. Biran gives an effective lower bound $N_0$. We construct examples verifying to the effect that the assertions of the Nagata-Biran conjecture can not hold for small number of points. We discuss cases where our construction fails. We observe also that there exists a strong relation between Riemann-Roch expected curves on $mathbb{P}^1 imes mathbb{P}^1$ and the symplectic packing problem. Biran relates the packing problem to the existence of solutions of certain Diophantine equations. We construct such solutions for any ample line bundle on $mathbb{P}^1 imes mathbb{P}^1$ and a relatively smallnumber of points. The solutions geometrically correspond to Riemann-Roch expected curves. Finally we discuss in how far the Biran number $N_0$ is optimal in the case of mathbb{P}^1 imes mathbb{P}^1. In fact we conjecture that it can be replaced by a lower number and we provide evidence justifying this conjecture.

  10. 四元数分析中λ-正则函数向量的带位移边值问题%A class of boundary value problem with shift for λ-regular function vectors in quaternion analysis

    Institute of Scientific and Technical Information of China (English)

    鄢盛勇

    2013-01-01

    A class of boundary value problem with a kind of shit for A- regular function vectors in quaternion analysis is considered. The integral representation of A- regular function vectors, and some integral operators are given. The boundary value problem is transformed into an integral equation problem. Applying integral equation method and the fixed-point theorem, the existence of solution to the problem is proved,and the integral representation of solution is obtained.%研究了四元数分析中λ-正则函数向量的一类带位移的边值问题.首先给出了λ-正则函数向量的积分表示,通过设计积分算子,将此边值问题转化为积分方程问题,借助积分方程理论和不动点原理证明了边值问题解的存在性,并给出了解的积分表达式.

  11. Problemas e limites da utilização do conceito de classe social em investigações epidemiológicas: uma revisão crítica da literatura Problems and limits in the utilization of the concept of social class in epidemiologic research: a critical review of the literature

    Directory of Open Access Journals (Sweden)

    Jorge José Santos Pereira Solla

    1996-06-01

    Full Text Available As limitações evidenciadas no emprego de variáveis empírico-indutivas nas alternativas hegemônicas da Epidemiologia para o tratamento das variações sócio-econômicas em coletivos humanos levaram à necessidade de novas propostas. Assim, foi introduzido o emprego da categoria classe social, operacionalizada de acordo com a inserção produtiva dos indivíduos estudados, apresentando potencialidades já evidenciadas em alguns estudos. O presente trabalho buscou identificar problemas e limites existentes na utilização do conceito de classe social na investigação epidemiológica. São abordados neste artigo alguns aspectos, entre eles: o tratamento das classes sociais enquanto agregados articulados no processo de investigação, a necessidade de adequar o esquema de operacionalização às particularidades de cada formação sócio-econômica, a simplificação efetivada no processo de redução do conceito de classe a uma série de variáveis articuladas empregadas, a necessidade de amostra relativamente grande, a existência de controvérsias na definição da inserção de classe de segmentos afastados da produção e de indivíduos com duas ou mais inserções produtivas distintas.The application of inductive empirical variables in hegemonic alternatives of Epidemiology in order to treat socioeconomic variations in human groups has displayed certain limitations raising the need for new proposals. The use of social class was thus introduced as an analytical category operated according to place in the productive process for the subjects under study. This choice has already shown potentialities in several studies. This paper was intended to identify some limits and problems occurring when using the social class concept in epidemiological research. Besides the need for an adequate theoretical framework, construction of categories consistent with both their theories and the levels of abstraction employed, and the concern for more

  12. Cylinder packing by simulated annealing

    Directory of Open Access Journals (Sweden)

    M. Helena Correia

    2000-12-01

    Full Text Available This paper is motivated by the problem of loading identical items of circular base (tubes, rolls, ... into a rectangular base (the pallet. For practical reasons, all the loaded items are considered to have the same height. The resolution of this problem consists in determining the positioning pattern of the circular bases of the items on the rectangular pallet, while maximizing the number of items. This pattern will be repeated for each layer stacked on the pallet. Two algorithms based on the meta-heuristic Simulated Annealing have been developed and implemented. The tuning of these algorithms parameters implied running intensive tests in order to improve its efficiency. The algorithms developed were easily extended to the case of non-identical circles.Este artigo aborda o problema de posicionamento de objetos de base circular (tubos, rolos, ... sobre uma base retangular de maiores dimensões. Por razões práticas, considera-se que todos os objetos a carregar apresentam a mesma altura. A resolução do problema consiste na determinação do padrão de posicionamento das bases circulares dos referidos objetos sobre a base de forma retangular, tendo como objetivo a maximização do número de objetos estritamente posicionados no interior dessa base. Este padrão de posicionamento será repetido em cada uma das camadas a carregar sobre a base retangular. Apresentam-se dois algoritmos para a resolução do problema. Estes algoritmos baseiam-se numa meta-heurística, Simulated Annealling, cuja afinação de parâmetros requereu a execução de testes intensivos com o objetivo de atingir um elevado grau de eficiência no seu desempenho. As características dos algoritmos implementados permitiram que a sua extensão à consideração de círculos com raios diferentes fosse facilmente conseguida.

  13. Multi-Objective Predictive Balancing Control of Battery Packs Based on Predictive Current

    Directory of Open Access Journals (Sweden)

    Wenbiao Li

    2016-04-01

    Full Text Available Various balancing topology and control methods have been proposed for the inconsistency problem of battery packs. However, these strategies only focus on a single objective, ignore the mutual interaction among various factors and are only based on the external performance of the battery pack inconsistency, such as voltage balancing and state of charge (SOC balancing. To solve these problems, multi-objective predictive balancing control (MOPBC based on predictive current is proposed in this paper, namely, in the driving process of an electric vehicle, using predictive control to predict the battery pack output current the next time. Based on this information, the impact of the battery pack temperature caused by the output current can be obtained. Then, the influence is added to the battery pack balancing control, which makes the present degradation, temperature, and SOC imbalance achieve balance automatically due to the change of the output current the next moment. According to MOPBC, the simulation model of the balancing circuit is built with four cells in Matlab/Simulink. The simulation results show that MOPBC is not only better than the other traditional balancing control strategies but also reduces the energy loss in the balancing process.

  14. Dimensions of a class of high-dimensional homogeneous Moran sets and Moran classes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A class of high-dimensional homogeneous Moran sets and Moran classes are introduced and some dimensional properties are studied. The Hausdorff dimension, modified lower box-counting dimension, lower and upper box-counting dimension, and packing dimension of high-dimensional homogeneous and partial homogeneous Cantor sets are determined. Moreover, a kind of fractal E is obtained, which is not regular but with the property Dimw(Ed)=dDimw(E), where w denotes any of the dimensions mentioned above.

  15. Close packing of rods on spherical surfaces

    Science.gov (United States)

    Smallenburg, Frank; Löwen, Hartmut

    2016-04-01

    We study the optimal packing of short, hard spherocylinders confined to lie tangential to a spherical surface, using simulated annealing and molecular dynamics simulations. For clusters of up to twelve particles, we map out the changes in the geometry of the closest-packed configuration as a function of the aspect ratio L/D, where L is the cylinder length and D the diameter of the rods. We find a rich variety of cluster structures. For larger clusters, we find that the best-packed configurations up to around 100 particles are highly dependent on the exact number of particles and aspect ratio. For even larger clusters, we find largely disordered clusters for very short rods (L/D = 0.25), while slightly longer rods (L/D = 0.5 or 1) prefer a global baseball-like geometry of smectic-like domains, similar to the behavior of large-scale nematic shells. Intriguingly, we observe that when compared to their optimal flat-plane packing, short rods adapt to the spherical geometry more efficiently than both spheres and longer rods. Our results provide predictions for experimentally realizable systems of colloidal rods trapped at the interface of emulsion droplets.

  16. Close packing of rods on spherical surfaces.

    Science.gov (United States)

    Smallenburg, Frank; Löwen, Hartmut

    2016-04-28

    We study the optimal packing of short, hard spherocylinders confined to lie tangential to a spherical surface, using simulated annealing and molecular dynamics simulations. For clusters of up to twelve particles, we map out the changes in the geometry of the closest-packed configuration as a function of the aspect ratio L/D, where L is the cylinder length and D the diameter of the rods. We find a rich variety of cluster structures. For larger clusters, we find that the best-packed configurations up to around 100 particles are highly dependent on the exact number of particles and aspect ratio. For even larger clusters, we find largely disordered clusters for very short rods (L/D = 0.25), while slightly longer rods (L/D = 0.5 or 1) prefer a global baseball-like geometry of smectic-like domains, similar to the behavior of large-scale nematic shells. Intriguingly, we observe that when compared to their optimal flat-plane packing, short rods adapt to the spherical geometry more efficiently than both spheres and longer rods. Our results provide predictions for experimentally realizable systems of colloidal rods trapped at the interface of emulsion droplets. PMID:27131565

  17. Bacteriological Survey of AFD (Meat Packing Plant

    Directory of Open Access Journals (Sweden)

    T. N. Rawal

    1974-04-01

    Full Text Available The paper describes the manufacturing process of freeze dried mutton from slaughtering to packing and makes an assessment of microbial build-up on equipment, hands of workers and environment in which the mutton comes in contact during processing.

  18. Simple Cloud Chambers Using Gel Ice Packs

    Science.gov (United States)

    Kamata, Masahiro; Kubota, Miki

    2012-01-01

    Although cloud chambers are highly regarded as teaching aids for radiation education, school teachers have difficulty in using cloud chambers because they have to prepare dry ice or liquid nitrogen before the experiment. We developed a very simple and inexpensive cloud chamber that uses the contents of gel ice packs which can substitute for dry…

  19. Computational Modelling of Particle Packing in Concrete

    NARCIS (Netherlands)

    He, H.

    2010-01-01

    Physical particle packing is becoming a hot topic in concrete technology as more and more types of granular materials are used in concrete either for ecological or for engineering purposes. Although various analytical methods have been developed for optimum mixture design, comprehensive information

  20. The benefits of using customized procedure packs.

    Science.gov (United States)

    Baines, R; Colquhoun, G; Jones, N; Bateman, R

    2001-01-01

    Discrete item purchasing is the traditional approach for hospitals to obtain consumable supplies for theatre procedures. Although most items are relatively low cost, the management and co-ordination of the supply chain, raising orders, controlling stock, picking and delivering to each operating theatre can be complex and costly. Customized procedure packs provide a solution. PMID:11892113

  1. Porous bead packings for gas chromatography

    Science.gov (United States)

    Pollock, G. E.; Woeller, F. H.

    1979-01-01

    Porous polyaromatic packing beads have low polarity, high efficiency, short retention time, and may be synthesized in size range of 50 to 150 micrometers (100 to 270 mesh). Mechanically strong beads may be produced using various materials depending on elements and compounds to be identified.

  2. The P.E.A.C.E. Pack: A Computerized Online Assessment of School Bullying

    Science.gov (United States)

    Slee, Phillip T.; Mohyla, Jury

    2014-01-01

    School bullying is an international problem with harmful outcomes for those involved. This study describes the design and field testing of an innovative computer-based social learning tool for assessing student perceptions of bullying developed for an Australian intervention program called the P.E.A.C.E. Pack. Students rate their peer group…

  3. 大学生出勤率问题中学生与教师的博弈分析%The Game Theory Aanalysis of The Students and The Teacher in The Problem of College Students Class Attendance Rate

    Institute of Scientific and Technical Information of China (English)

    徐伟斌; 夏云龙

    2011-01-01

    博弈论的创新应用是解决各种现实问题的有力工具。在校大学生上课出勤率低是高等教育中的一个普遍存在的问题,长期以来没有得到应有的重视而一直无法有效地解决。已有的文献对在校大学生上课出勤率低的问题有很多研究,但多数从高等教育管理等教育学角度出发,运用信息经济学和博弈论工具来分析这一问题的很少。本文通过对教师与学生在出勤行为上的总结、分析和归纳,建立了教师与学生的各自收益函数,然后建立模型进行分析。通过寻找博弈矩阵的纯策略纳什均衡和混合策略纳什均衡,得到均衡状态下教师点名及"懒惰学生"旷课的概率。并在此基础上对如何提高学生出勤率给出建议。%The innovative application of game theory can help solve many practical problems.The low class attendance rate is a widelyspread problem in universities and colleges,and it has not received due attention and been effectively addressed now.Existing literature on the problem of low class attendance in universities and colleges mainly did their research from the aspect of the higher educational system.Those analyzing this issue with the tools of information economics and game theory were very little.This article is based on the analysis of the behavior of teachers and the students.We set up teachers and students' profit functions and then find out a pure strategy Nash equilibrium and the mixed strategy Nash equilibrium,getting the probability of absenteeism of the "lazy students" and the rollcall,hoping to give some suggestions on how to increase the class attendance rate based on our findings.

  4. The Effect of Using Problem-Based Learning in Middle School Gifted Science Classes on Student Achievement and Students' Perceptions of Classroom Quality

    Science.gov (United States)

    Horak, Anne Karen

    The purpose of this study was to explore the impact of the Problem Based Learning (PBL) units developed by a large suburban school district in the mid-Atlantic for the middle school gifted science curriculum on: a) students' performance on standardized tests in middle school Science, as measured by a sample of relevant test questions from a district-managed test bank; and b) students' perceptions of classroom quality according to the constructs of: meaningfulness, challenge, choice, self-efficacy, and appeal as measured by the Student Perceptions of Classroom Quality scale (SPOCQ) (Gentry & Owens, 2004). A group of students taught using PBL and a comparison group of students taught using traditional instruction were studied. Between the two groups, a total of 457 students participated in the study. Pre and post student achievement data were collected using a 25 item multiple choice test that aligned with state and local objectives. It was hypothesized there would be no significant differences in gain scores or perceptions between a group of students taught using PBL in comparison to the group taught using traditional methods. Data analysis indicated statistically significant gain scores in both of the groups with a higher gain score in the PBL group. Data analysis also revealed statistically significant differences in the total score on the SPOCQ in favor of the PBL group. This study found positive effects for well-implemented PBL instruction with these students. However, much more remains to be known. Future research should include longitudinal studies expanded to different subjects, grade levels and populations of students.

  5. Mass transfer characteristics in a rotating packed bed with split packing

    Institute of Scientific and Technical Information of China (English)

    Youzhi Liu; Deyin Gu; Chengcheng Xu; Guisheng Qi; Weizhou Jiao

    2015-01-01

    The rotating packed bed (RPB) with split packing is a novel gas–liquid contactor, which intensifies the mass transfer processes controlled by gas-side resistance. To assess its efficacy, the mass transfer characteristics with adjacent rings in counter-rotation and co-rotation modes in a split packing RPB were studied experimentally. The physical absorption system NH3–H2O was used for characterizing the gas volumetric mass transfer coeffi-cient (kyae) and the effective interfacial area (ae) was determined by chemical absorption in the CO2–NaOH sys-tem. The variation in kyae and ae with the operating conditions is also investigated. The experimental results indicated that kyae and ae for counter-rotation of the adjacent packing rings in the split packing RPB were higher than those for co-rotation, and both counter-rotation and co-rotation of the split packing RPB were superior over conventional RPBs under the similar operating conditions.

  6. The statistical character of packed-bed heat transport properties

    OpenAIRE

    Wijngaarden, R.J.; Westerterp, K. R.

    1992-01-01

    Packed beds are essentially heterogeneous on a pellet scale. For random packed beds this heterogeneity causes a statistical character both on a pellet and bed scale. We discuss experimental results which deal with bed-scale statistics.

  7. Self-similar space-filling packings in three dimensions

    OpenAIRE

    Baram, Reza Mahmoodi; Herrmann, Hans J.

    2003-01-01

    We develop an algorithm to construct new self-similar space-filling packings of spheres. Each topologically different configuration is characterized by its own fractal dimension. We also find the first bi-cromatic packing known up to now.

  8. Power Cycle Testing of Press-Pack IGBT Chips

    OpenAIRE

    Frank, Øyvind Bjerke

    2014-01-01

    In this thesis the power cycling capability of individual press-pack IGBT chips is investigated. Press-pack is a packaging technology used for power semiconductors. For press-packs, both thermal and electrical contact to the semiconductor chip is obtained by the application of force on the package. Press-pack IGBTs is claimed by the manufacturers to be especially suitable for high-power applications with large variations in power output. Power cycle testing is an accelerated lifetime stress t...

  9. Third-order thermo-mechanical properties for packs of Platonic solids using statistical micromechanics

    Science.gov (United States)

    Gillman, A.; Amadio, G.; Matouš, K.; Jackson, T. L.

    2015-01-01

    Obtaining an accurate higher order statistical description of heterogeneous materials and using this information to predict effective material behaviour with high fidelity has remained an outstanding problem for many years. In a recent letter, Gillman & Matouš (2014 Phys. Lett. A 378, 3070–3073. ()) accurately evaluated the three-point microstructural parameter that arises in third-order theories and predicted with high accuracy the effective thermal conductivity of highly packed material systems. Expanding this work here, we predict for the first time effective thermo-mechanical properties of granular Platonic solid packs using third-order statistical micromechanics. Systems of impenetrable and penetrable spheres are considered to verify adaptive methods for computing n-point probability functions directly from three-dimensional microstructures, and excellent agreement is shown with simulation. Moreover, a significant shape effect is discovered for the effective thermal conductivity of highly packed composites, whereas a moderate shape effect is exhibited for the elastic constants.

  10. Fluid modelling of a packed bed dielectric barrier discharge plasma reactor

    Science.gov (United States)

    Van Laer, Koen; Bogaerts, Annemie

    2016-02-01

    A packed bed dielectric barrier discharge plasma reactor is computationally studied with a fluid model. Two different complementary axisymmetric 2D geometries are used to mimic the intrinsic 3D problem. It is found that a packing enhances the electric field strength and electron temperature at the contact points of the dielectric material due to polarization of the beads by the applied potential. As a result, these contact points prove to be of direct importance to initiate the plasma. At low applied potential, the discharge stays at the contact points, and shows the properties of a Townsend discharge. When a high enough potential is applied, the plasma will be able to travel through the gaps in between the beads from wall to wall, forming a kind of glow discharge. Therefore, the inclusion of a so-called ‘channel of voids’ is indispensable in any type of packed bed modelling.

  11. A packed bed dehumidifier/regenerator for solar air conditioning with liquid desiccants

    Science.gov (United States)

    Factor, H. M.; Grossman, G.

    1980-01-01

    A packed column air-liquid contactor has been studied in application to air dehumidification and regeneration in solar air conditioning with liquid desiccants. A theoretical model has been developed to predict the performance of the device under various operating conditions. Computer simulations based on the model are presented which indicate the practical range of air to liquid flux ratios and associated changes in air humidity and desiccant concentration. An experimental apparatus has been constructed and experiments performed with Monoethylene Glycol (MEG) and Lithium Bromide as desiccants. MEG experiments have yielded inaccurate results and have pointed out some practical problems associated with the use of Glycols. LiBr experiments show very good agreement with the theoretical model. Preheating of the air is shown to greatly enhance desiccant regeneration. The packed column yields good results as a dehumidifier/regenerator, provided pressure drop can be reduced with the use of suitable packing.

  12. Multi-objective optimal design of lithium-ion battery packs based on evolutionary algorithms

    Science.gov (United States)

    Severino, Bernardo; Gana, Felipe; Palma-Behnke, Rodrigo; Estévez, Pablo A.; Calderón-Muñoz, Williams R.; Orchard, Marcos E.; Reyes, Jorge; Cortés, Marcelo

    2014-12-01

    Lithium-battery energy storage systems (LiBESS) are increasingly being used on electric mobility and stationary applications. Despite its increasing use and improvements of the technology there are still challenges associated with cost reduction, increasing lifetime and capacity, and higher safety. A correct battery thermal management system (BTMS) design is critical to achieve these goals. In this paper, a general framework for obtaining optimal BTMS designs is proposed. Due to the trade-off between the BTMS's design goals and the complex modeling of thermal response inside the battery pack, this paper proposes to solve this problem using a novel Multi-Objective Particle Swarm Optimization (MOPSO) approach. A theoretical case of a module with 6 cells and a real case of a pack used in a Solar Race Car are presented. The results show the capabilities of the proposal methodology, in which improved designs for battery packs are obtained.

  13. Two Bandwidth Packing Algorithms for the Centralized Wireless Network and Their Average-case Analysis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents a detail analysis of two bandwidth packing algorithms, used for processing connection requests in the centralized wireless network. Each call comes with a specific bandwidth request. A request can be satisfied only if there is sufficient bandwidth available during resource scheduling and allocation. Unsatisfied requests were held in a queue. The metric of bandwidth utilization ratio was used to quantify the performance of our algorithms. By theoretical analysis, our algorithms can improve the average bandwidth usage ratio significantly,about 8%~ 10% without adding much computation complexity. Moreover, our algorithms outperform next fit with fragmentation (NFF) algorithm when the bandwidth resource is scarce. In this paper, the contributions follows: Introducing bandwidth packing problem into wireless network; Proposing two new bandwidth packing algorithms for wireless network where the complicate scheduling algorithms are prohibited; Studying the average performance of our algorithms mathematically, which agree well with the simulation results.

  14. Pattern Generation by Bubble Packing Method

    Directory of Open Access Journals (Sweden)

    Goel V.K.

    2013-06-01

    Full Text Available This paper presents a new computational method forornamental Pattern design. The work is a concerted effort ofevaluation of various methods and the comparatively betterprocess is used for designing keeping in mind the accuracyrequirement for such Indian traditional ethnic designs. The firststep in the process to apply the CAD tools to design the patterns.Small semantics (profile are made using the mathematicalmodelling to make different pattern. Geometric constraints suchas scaling, rotation, transformation etc. are applied to make andmodify the profiles. To create patterns, obtains node locationsthrough a physically based particle simulation, which we call'bubble packing. Bubbles are closely packed on the corners,edges and on the surface domain, and nodes are placed at thecenters of the bubbles. Experimental results show that ourmethod can create high quality ornamental patterns. Thefabrication of the ornaments is on rapid prototype machine.

  15. Is incest common in gray wolf packs?

    Science.gov (United States)

    Smith, D.; Meier, T.; Geffen, E.; Mech, L.D.; Burch, J.W.; Adams, L.G.; Wayne, R.K.

    1997-01-01

    Wolf packs generally consist of a breeding pair and their maturing offspring that help provision and protect pack young. Because the reproductive tenure in wolves often is short, reproductively mature offspring might replace their parents, resulting in sibling or parent-offspring matings. To determine the extent of incestuous pairings, we measure relatedness based on variability in 20 microsatellite loci of mated pairs, parent-offspring pairs and siblings in two populations of gray wolves. Our 16 sampled mated pairs had values of relatedness not overlapping those of known parent-offspring or sibling dyads, which is consistent with their being unrelated or distantly related. These results suggest that full siblings or a parent and their offspring rarely mate and that incest avoidance is an important constraint on gray wolf behavioral ecology.

  16. Helix-packing motifs in membrane proteins.

    Science.gov (United States)

    Walters, R F S; DeGrado, W F

    2006-09-12

    The fold of a helical membrane protein is largely determined by interactions between membrane-imbedded helices. To elucidate recurring helix-helix interaction motifs, we dissected the crystallographic structures of membrane proteins into a library of interacting helical pairs. The pairs were clustered according to their three-dimensional similarity (rmsd universe of common transmembrane helix-pairing motifs is relatively simple. The largest cluster, which comprises 29% of the library members, consists of an antiparallel motif with left-handed packing angles, and it is frequently stabilized by packing of small side chains occurring every seven residues in the sequence. Right-handed parallel and antiparallel structures show a similar tendency to segregate small residues to the helix-helix interface but spaced at four-residue intervals. Position-specific sequence propensities were derived for the most populated motifs. These structural and sequential motifs should be quite useful for the design and structural prediction of membrane proteins.

  17. TIBER-II TF winding pack design

    International Nuclear Information System (INIS)

    The superconducting, toroidal-field (TF) coils in the Tokamak Ignition/Burn Engineering Reactor (TIBER II) are designed with cable-in-conduit conductor (CICC) using NB3Sn composite strands. To design the CICC winding pack, the authors used an optimization technique that maximizes the conductor stability without violating the constraints imposed by the structure, electrical insulation, quench protection, and fabrication technique. Detailed helium-properties codes calculate the heat removal along a flow path, and detailed field calculations determine the temperature, current, and stability margins. The conductor sheath is designed as distributed structure to partially support the combined in-plane and out-of-plane loads generated within the winding pack. Pancakes of the coil are wound, reacted, and insulated before being potted in the case. This design is aggressive but fully consistent with good engineering practice

  18. Body Packing: From Seizures to Laparotomy

    Directory of Open Access Journals (Sweden)

    Joanna M. Janczak

    2015-01-01

    Full Text Available Body packing is a common method for illegal drug trafficking. Complications associated with body packing can be severe and even lead to rapid death. Thus, a timely diagnosis is warranted. As most body packers initially do not show any symptoms, making a correct diagnosis can be rather challenging. We describe a case of a 41-year-old male, who was admitted with an epileptic seizure and who turned out to be a cocaine intoxicated body packer. Due to neurological and cardiovascular deterioration an emergency surgery was performed. Four bags of cocaine could be removed. We discuss the current management regimen in symptomatic and asymptomatic body packers and highlight pearls and pitfalls with diagnosis and treatment.

  19. Packing and Disorder in Substituted Fullerenes

    KAUST Repository

    Tummala, Naga Rajesh

    2016-07-15

    Fullerenes are ubiquitous as electron-acceptor and electron-transport materials in organic solar cells. Recent synthetic strategies to improve the solubility and electronic characteristics of these molecules have translated into a tremendous increase in the variety of derivatives employed in these applications. Here, we use molecular dynamics (MD) simulations to examine the impact of going from mono-adducts to bis- and tris-adducts on the structural, cohesive, and packing characteristics of [6,6]-phenyl-C60-butyric acid methyl ester (PCBM) and indene-C60. The packing configurations obtained at the MD level then serve as input for density functional theory calculations that examine the solid-state energetic disorder (distribution of site energies) as a function of chemical substitution. The variations in structural and site-energy disorders reflect the fundamental materials differences among the derivatives and impact the performance of these materials in thin-film electronic devices.

  20. Meromorphic Vector Fields and Circle Packings

    DEFF Research Database (Denmark)

    Dias, Kealey

    of dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions or meromorphic (allowing poles...... to the development of a theory of discrete analytic functions, which is a new tool in conformal geometry that can be used to implement many of the classical tools from complex analysis. Circle packing is a relatively new subject that has a great potential for technological applications, specifically for imaging......The objective of the Ph.D. project is to initiate a classification of bifurcations of meromorphic vector fields and to clarify their relation to circle packings. Technological applications are to image analysis and to effective grid generation using discrete conformal mappings. The two branches...

  1. The Existence of Three Positive Solutions for a Class of Nonlinear Three-Point Boundary Value Problem with ρ-Laplacian%一类具p-Laplace非线性三点边值问题三个正解的存在性

    Institute of Scientific and Technical Information of China (English)

    李相锋; 徐宏武

    2009-01-01

    This paper deals with the existence of three positive solutions for a class of nonlinear singular three-point boundary value problem with p-Laplacian. By means of a fixed point theo- rem duo to Leggett and Williams, sufficient condition for the existence of at least three positive solutions to the nonlinear singular three-point boundary value problem is established.

  2. The Paradox of Paperless Classes.

    Science.gov (United States)

    Lackie, Paula

    1998-01-01

    Describes paperless classes developed at Carleton College that augment traditional classes by giving students and faculty the ability to share digital course-related materials via the campus computer network. Presents a case study of a managerial economics course, and includes problems with various aspects of the course and solutions. (LRW)

  3. The close-packed triple helix as a possible new structural motif for collagen

    CERN Document Server

    Bohr, Jakob

    2010-01-01

    The one-dimensional problem of selecting the triple helix with the highest volume fraction is solved and hence the condition for a helix to be close-packed is obtained. The close-packed triple helix is shown to have a pitch angle of $v_{CP} =43.3 ^\\circ$. Contrary to the conventional notion, we suggest that close packing form the underlying principle behind the structure of collagen, and the implications of this suggestion are considered. Further, it is shown that the unique zero-twist structure with no strain-twist coupling is practically identical to the close-packed triple helix. Some of the difficulties for the current understanding of the structure of collagen are reviewed: The ambiguity in assigning crystal structures for collagen-like peptides, and the failure to satisfactorily calculate circular dichroism spectra. Further, the proposed new geometrical structure for collagen is better packed than both the 10/3 and the 7/2 structure. A feature of the suggested collagen structure is the existence of a ce...

  4. 48 CFR 211.272 - Alternate preservation, packaging, and packing.

    Science.gov (United States)

    2010-10-01

    ..., packaging, and packing. 211.272 Section 211.272 Federal Acquisition Regulations System DEFENSE ACQUISITION... Requirements Documents 211.272 Alternate preservation, packaging, and packing. Use the provision at 252.211-7004, Alternate Preservation, Packaging, and Packing, in solicitations which include...

  5. 48 CFR 552.211-87 - Export packing.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Export packing. 552.211-87... FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Text of Provisions and Clauses 552.211-87 Export packing. As prescribed in 511.204(b)(7), insert the following clause: Export Packing (JAN 2010)...

  6. 21 CFR 133.124 - Cold-pack cheese food.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Cold-pack cheese food. 133.124 Section 133.124 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Cheese and Related Products § 133.124 Cold-pack cheese food. (a)(1) Cold-pack cheese food is the...

  7. CoolPack – Simulation tools for refrigeration systems

    DEFF Research Database (Denmark)

    Jakobsen, Arne; Rasmussen, Bjarne D.; Andersen, Simon Engedal

    1999-01-01

    CoolPack is a collection of programs used for energy analysis and optimisation of refrigeration systems. CoolPack is developed at the Department of Energy Engineering at the Technical University of Denmark. The Danish Energy Agency finances the project. CoolPack is freeware and can be downloaded ...

  8. 27 CFR 24.255 - Bottling or packing wine.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottling or packing wine..., DEPARTMENT OF THE TREASURY LIQUORS WINE Storage, Treatment and Finishing of Wine Bottling, Packing, and Labeling of Wine § 24.255 Bottling or packing wine. (a) General. Proprietors of a bonded wine premises...

  9. 36 CFR 1002.16 - Horses and pack animals.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Horses and pack animals. 1002... AND RECREATION § 1002.16 Horses and pack animals. The following are prohibited: (a) The use of animals other than those designated as “pack animals” for purposes of transporting equipment. (b) The use...

  10. 36 CFR 2.16 - Horses and pack animals.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Horses and pack animals. 2.16... RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.16 Horses and pack animals. The following are prohibited: (a) The use of animals other than those designated as “pack animals” for purposes of...

  11. 36 CFR 34.10 - Saddle and pack animals.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Saddle and pack animals. 34... INTERIOR EL PORTAL ADMINISTRATIVE SITE REGULATIONS § 34.10 Saddle and pack animals. The use of saddle and pack animals is prohibited without a permit from the Superintendent....

  12. Breakup of Pack Ice, Antarctic Ice Shelf

    Science.gov (United States)

    1991-01-01

    Breakup of Pack Ice along the periphery of the Antarctic Ice Shelf (53.5S, 3.0E) produced this mosaic of ice floes off the Antarctic Ice Shelf. Strong offshore winds, probably associated with strong katabatic downdrafts from the interior of the continent, are seen peeling off the edges of the ice shelf into long filamets of sea ice, icebergs, bergy bits and growlers to flow northward into the South Atlantic Ocean. 53.5S, 3.0E

  13. A Controlled New Process of Pack Aluminization

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhi-rong; MA Liu-bao; LI Pei-ning; XU Hong

    2004-01-01

    Aluminum diffusion coatings are often prepared by a pack aluminization technique, which is a specific variety of chemical vapor deposition (CVD) method. The coating process takes place in a bed containing a mixed powder that serves as a source of the coatings forming element. The phase composition of the diffusion layer obtained depends on the activity of the Al during the pack aluminization processing. In this work, the proportion of Al to special additive powder in the pack and the treatment temperature are adjusted to achieve the desired surface composition of aluminized layer. The aluminized 20 plain carbon steel and HK40 austenitic steel were investigated by optical microscopy (OM) , X-ray diffraction (XRD)and microsclerometer. The results showed that the desired FeAl, Fe3Al and NiAl were respectively formed on the 20 plain carbon steel and HK40 austenitic steel, and the aluminides FeAl3, Fe2Al5 or Ni2Al3, NiAl3 could be inhibited.

  14. A Controlled New Process of Pack Aluminization

    Institute of Scientific and Technical Information of China (English)

    HUANGZhi-rong; MALiu-bao; LIPei-ning; XUHong

    2004-01-01

    Aluminum diffusion coatings are often prepared by a pack aluminization technique, which is a specific variety of chemical vapor deposition (CVD) method. The coating process takes place in a bed containing a mixed powder that serves as a source of the coatings forming element. The phase composition of the diffusion layer obtained depends on the activity of the Al during the pack aluminization processing. In this work, the proportion of Al to special additive powder in the pack and the treatment temperature are adjusted to achieve the desired surface composition of aluminized layer. The aluminized 20 plain carbon steel and HK40 austenitic steel were investigated by optical microscopy (OM) , X-ray diffraction (XRD) and microsclerometer. The results showed that the desired FeAl, Fe3Al and NiAl were respectively formed on the 20 plain carbon steel and HK40 austenitic steel, and the aluminides FeAl3, Fe2Al5 or Ni2Al3, NiAl3 could be inhibited.

  15. The Initial Boundary Value Problem of a Class of Diffusion Equations and Its Application%一类扩散方程的初边值问题及其应用

    Institute of Scientific and Technical Information of China (English)

    谈骏渝

    2012-01-01

    对一类扩散方程的初边值问题给出了以球贝塞尔函数表示的级数解,由此得到了裂变产物在燃料芯块中扩散问题的解以及裂变产物扩散的释放速度,为有效开展对裂变产物的扩散过程及反应堆燃料元件破损探测信号的定量分析提供了条件.%A series solution expressed by the Bessel function is given to the initial boundary value problems of a class of diffusion equations.Hence,the solutions to the proliferation problems of fission products in the fuel pellets and their release rates are obtained,thus providing necessary conditions for the quantitative analysis of the diffusion process of fission products and the detection of the signals of the reactor fuel element's damage.

  16. My Class

    Institute of Scientific and Technical Information of China (English)

    赵传怡

    2006-01-01

    My name is Zhao Chuanyi.I am in Class Ten Grade seven.There are 61 students in our class.And 26 are girls and 35 are boys.One is from America.Boys like football and basketball.Girls like singing and dancing.We are all

  17. Word classes

    DEFF Research Database (Denmark)

    Rijkhoff, Jan

    2007-01-01

    a parts-of-speech system that includes the categories Verb, Noun, Adjective and Adverb, other languages may use only a subset of these four lexical categories. Furthermore, quite a few languages have a major word class whose members cannot be classified in terms of the categories Verb – Noun – Adjective...

  18. Spherical Cap Packing Asymptotics and Rank-Extreme Detection

    CERN Document Server

    Zhang, Kai

    2015-01-01

    We study the spherical cap packing problem with a probabilistic approach. Such probabilistic considerations result in an asymptotic sharp universal uniform bound on the maximal inner product between any set of unit vectors and a stochastically independent uniformly distributed unit vector. When the set of unit vectors are themselves independently uniformly distributed, we further develop the extreme value distribution limit of the maximal inner product, which characterizes its uncertainty around the bound. As applications of the above asymptotic results, we derive (1) an asymptotic sharp universal uniform bound on the maximal spurious correlation, as well as its uniform convergence in distribution when the explanatory variables are independently Gaussian distributed; and (2) an asymptotic sharp universal bound on the maximum norm of a low-rank elliptically distributed vector, as well as related limiting distributions. With these results, we develop a fast detection method for a low-rank structure in high-dime...

  19. Perturbing the hexagonal circle packing: a percolation perspective

    CERN Document Server

    Benjamini, Itai

    2011-01-01

    We consider the hexagonal circle packing with radius 1/2 and perturb it by letting the circles move as independent Brownian motions for time t. It is shown that, for small enough t, the union of the circles will contain an infinite connected component (module a Monte Carlo estimate for a fixed high dimensional integral). On the other hand, if \\Pi_t is the point process induced by the center of the circles at time t, then, as t goes to infinity, the critical radius for circles centered at \\Pi_t to contain an infinite component converges to that of continuum percolation (which was shown---module a Monte Carlo estimate---by Balister, Bollobas and Walters to be strictly bigger than 1/2). We conjecture the existence of a deterministic critical time marking a phase transition for the existence of an infinite component of the union of the circles. Further open problems are discussed.

  20. Highly efficient capillary columns packed with superficially porous particles via sequential column packing.

    Science.gov (United States)

    Treadway, James W; Wyndham, Kevin D; Jorgenson, James W

    2015-11-27

    Highly efficient capillary columns packed with superficially porous particles were created for use in ultrahigh pressure liquid chromatography. Superficially porous particles around 1.5μm in diameter were packed into fused silica capillary columns with 30, 50, and 75μm internal diameters. To create the columns, several capillary columns were serially packed from the same slurry, with packing progress plots being generated to follow the packing of each column. Characterization of these columns using hydroquinone yielded calculated minimum reduced plate heights as low as 1.24 for the most efficient 30μm internal diameter column, corresponding to over 500,000plates/m. At least one highly efficient column (minimum reduced plate height less than 2) was created for all three of the investigated column inner diameters, with the smallest diameter columns having the highest efficiency. This study proves that highly efficient capillary columns can be created using superficially porous particles and shows the efficiency potential of these particles.

  1. Eating less from bigger packs: Preventing the pack size effect with diet primes.

    Science.gov (United States)

    Versluis, Iris; Papies, Esther K

    2016-05-01

    An increase in the package size of food has been shown to lead to an increase in energy intake from this food, the so-called pack size effect. Previous research has shown that providing diet-concerned individuals with a reminder, or prime, of their dieting goal can help them control their consumption. Here, we investigated if providing such a prime is also effective for reducing the magnitude of the pack size effect. We conducted two experiments in which the cover of a dieting magazine (Experiment 1) and diet-related commercials (Experiment 2) served as diet goal primes. Both experiments had a 2 (pack size: small vs. large) × 2 (prime: diet vs. control) × 2 (dietary restraint: high vs. low) between participants design. We measured expected consumption of four snack foods in Experiment 1 (N = 477), and actual consumption of M&M's in Experiment 2 (N = 224). Results showed that the diet prime reduced the pack size effect for both restrained and unrestrained eaters in Experiment 1 and for restrained eaters only in Experiment 2. Although effect sizes were small, these findings suggest that a diet prime motivates restrained eaters to limit their consumption, and as a result the pack size has less influence on the amount consumed. We discuss limitations of this research as well as potential avenues for further research and theoretical and practical implications. PMID:26876911

  2. Class size versus class composition

    DEFF Research Database (Denmark)

    Jones, Sam

    Raising schooling quality in low-income countries is a pressing challenge. Substantial research has considered the impact of cutting class sizes on skills acquisition. Considerably less attention has been given to the extent to which peer effects, which refer to class composition, also may affect...... outcomes. This study uses new microdata from East Africa, incorporating test score data for over 250,000 children, to compare the likely efficacy of these two types of interventions. Endogeneity bias is addressed via fixed effects and instrumental variables techniques. Although these may not fully mitigate...

  3. 以问题为基础的教学法在护理学基础实验课教学中的应用%Application of problem-based learning in experimental classes of fundamental nursing

    Institute of Scientific and Technical Information of China (English)

    颜文贞; 王萍; 王芳

    2009-01-01

    Objective To investigate the role of problem-based learning (PBL) in the improve-ment of students' comprehensive ability in experimental classes of fundamental nursing. Methods A total of 172 nursing students were randomly divided into the experimental group (n=76) and the control group (n=96), they received PBL and traditional education, respectively.The teaching effect was compared using X2 tesL Results The experimental group was better than the control group in comprehensive a-bility such as communication skills, operant skills, coping skills, health education, appearance and at-titude. Conclusions PBL can promote the nursing students to understand the comprehensive information of special problems, and improve their skills of resolving practical problems and autonomic learning.%目的 探讨以问题为基础的教学法在护理学基础实验课教学中对提高学生综合能力的作用.方法 将172名学生随机分为实验组76名和对照组96名,分别采用以问题为基础的教学法和传统教学法,比较2组的教学效果,进行X2检验.结果 实验组在沟通技巧、操作技能、应变能力、健康教育、仪表态度等方面的综合能力显著优于对照组.结论 以问题为基础的教学法可促进学生学习有关问题的全面知识,并提高学生解决实际问题和自主学习的能力.

  4. Problem analysis of 58 reviews from Specialty Nurse Certification Class%58篇专科护士认证班学员综述中存在的问题分析

    Institute of Scientific and Technical Information of China (English)

    周霞; 张岚; 高振辉; 刘美满

    2012-01-01

    Objective: To analyze the problems of 58 students' reviews from one Specialty Nurse (SN) Certification Class in Beijing, and provide reference for better training on SN's review writing. Methods: Some nurse experts reviewed 58 SN's manuscripts by using a self-designed questionnaire. Then we summarized and analyzed the problems. Results: The main problem of the 58 reviews existed in topic selection, manuscript framework, references citing, written language, etc. It may be related to SN's poor research ability, low writing level and lack of literature search skill. Conclusion: We should strengthen review writing training for SN to improve their research ability.%目的:通过对北京市某专科护士认证班58名学员所撰写的综述存在的问题进行分析,以期为专科护士综述写作能力的培养提供建议.方法:采用自设的一般资料调查表,收集护理专家对北京市某专科护士认证班58名学员综述的审稿意见,将其存在的问题进行归纳总结并对问题进行分析.结果:58篇综述中主要在选题、结构、参考文献、文字表达等方面存在问题,与专科护士科研意识薄弱,写作水平较低,文献检索知识不足等有关.结论:平时应重视提升专科护士的科研意识,加强对专科护士进行综述写作能力的培训.

  5. Translation in ESL Classes

    Directory of Open Access Journals (Sweden)

    Nagy Imola Katalin

    2015-12-01

    Full Text Available The problem of translation in foreign language classes cannot be dealt with unless we attempt to make an overview of what translation meant for language teaching in different periods of language pedagogy. From the translation-oriented grammar-translation method through the complete ban on translation and mother tongue during the times of the audio-lingual approaches, we have come today to reconsider the role and status of translation in ESL classes. This article attempts to advocate for translation as a useful ESL class activity, which can completely fulfil the requirements of communicativeness. We also attempt to identify some activities and games, which rely on translation in some books published in the 1990s and the 2000s.

  6. A STUDY OF THE COMPLICATIONS OF RIBBON GAUZE IMPREGNATED WITH SOFRAMYCIN NASAL PACKING AND MEROCEL PACKING IN POST SEPTOPLASTY PATIENTS

    Directory of Open Access Journals (Sweden)

    Swaroop Dev

    2015-03-01

    Full Text Available OBJECTIVE: To compare the complications of Ribbon Gauze Impregnated with soframycin nasal packing and Merocel Packing in Post Septoplasty patients. MATERIALS AND METHODS : A randomized trial was conducted in the department of Otorhinolaryngology and Head and Neck Sur gery of Sri Siddhartha Medical College, Tumkur, Karnataka from July 2011 - September 2014. In our study 100 patients who underwent septoplasty were divided into two groups. Group A and Group B consisting of 50 patients each. The Patients were alternately ass igned into the two groups. In patients of Group A Merocel packing (size 8cm impregnated with soframycin ointement was done. In patients of Group B Ribbon Gauze Impregnated with Soframycin packing was done. Cottle’s maxillary - premaxillary septoplasty appr oach was employed in all the 100 patients under local anaesthesia. The complications of nasal packing like Bleeding during pack in situ, Bleeding during pack removal, Pain score during pack in - situ, Pain score during pack removal, Septal Hematoma, nasal sy nechia and Septal perforation were compared between the two groups. Both the groups were followed up for 8 weeks. RESULTS: In our study group A patients show statistically significant less pain score while pack was in situ and during pack removal compared with group B patients. Bleeding during pack removal and development of synechia in group A patients were statistically les s compared to group B patients. None of the patients developed septal hematoma and septal perforation in both the groups. CONCLUSION: The use of Merocel nasal packing in post septoplasty patients have better compliance with respect to pain compared with co nventional ribbon gauze. Although bleeding is well controlled with both Merocel and Ribbon gauze when the pack is in situ, Merocel cause less bleeding during pack removal and less nasal synechia compared to conventional ribbon gauze.

  7. Effects of Airlfow Field on Droplets Diameter inside the Corrugated Packing of a Rotating Packed Bed

    Institute of Scientific and Technical Information of China (English)

    Xu Chengcheng; Jiao Weizhou; Liu Youzhi; Guo Liang; Yuan Zhiguo; Zhang Qiaoling

    2014-01-01

    Rotating packing bed (RPB) has a better mixing performance than traditional mixers and shows potential applica-tion in the petroleum industry. However, acquisition of information about the mixing process directly through experiments is dififcult because of the compact structure and complex multiphase lfow pattern in RPB. To study the mixing character-istic, Fluent, the computational lfuid dynamics (CFD) software, was used to explore the effect of airlfow ifeld on droplet diameter. For conducting calculations, the gas-liquid two-phase lfow inside the packing was simulated with the RNG k-εturbulence model and the Lagrange Discrete Phase Model (DPM), respectively. The numerical calculation results showed that coalescence and breakup of droplets can take place in the gas phase lfow inside the packing and can be strengthened with increased rotating speed, thereby leading to the enlargement of the average diameter.

  8. Sugar exported: sugar packed in containers

    Directory of Open Access Journals (Sweden)

    José Alberto Yemal

    2010-04-01

    Full Text Available This paper presents a study in the port sector specialized in handling of bagged sugar. Sugar has always been exported in bags of 50 kg, placed directly in the holds of ships for general cargo. It appears that this form of transport has become obsolete now, the market for the direct form of transport of sugar packed in containers. Companies involved in this type of port handling need understand the reasons that are influencing this new mode of transportation as a way to fit and remain active and competitive in the industry.

  9. Importance of packing in spiral defect chaos

    Indian Academy of Sciences (India)

    Kapilanjan Krishna

    2008-04-01

    We develop two measures to characterize the geometry of patterns exhibited by the state of spiral defect chaos, a weakly turbulent regime of Rayleigh-Bénard convection. These describe the packing of contiguous stripes within the pattern by quantifying their length and nearest-neighbor distributions. The distributions evolve towards unique distribution with increasing Rayleigh number that suggests power-law scaling for the dynamics in the limit of infinite system size. The techniques are generally applicable to patterns that are reducible to a binary representation.

  10. Cooperative Language learning in English Classes:Theory, Problems and Solutions%英语合作性学习的理论、存在的问题及对策

    Institute of Scientific and Technical Information of China (English)

    傅瑞屏; 冼绮霞

    2014-01-01

    和大多数的语言教学理论一样,合作性语言学习理论既有语言理论的支撑,也有学习理论的支持。合作性语言学习在英语课堂教学中的具体体现是小组学习活动,成功的英语小组合作学习的实施能够促进学生语言能力和认知的发展以及自主学习能力的提高。然而在实践中英语小组合作学习常常出现一些导致活动低效的问题,例如教师指令语不清晰、班额大导致小组活动难以实施及监控、话霸及角色僵化、学生在活动时使用母语等。为了提高合作性语言学习的成效,教师需要提高任务设计的能力、提高指令语的素养以及课堂管理和掌控的能力,等等,使学生能够切实运用英语完成语言学习任务。%Cooperative language learning theory is prevailing in China′ English language classroom at present and the heat will continue for a long time. Cooperative language learning is often carried out in form of group work. Effective cooperative learning can enhance students′ communicative ability, cognition and autonomous learning ability while unsuccessful implementation of cooperative learning will diminish the effect of classroom teaching and learning. A series of problems are found in cooperative learning in groups in China such as ineffective teacher instruction, too large a class, turn domination and role fossilization, too much Chinese in carrying out tasks, etc, which should be reflected and dealt with. Some solutions are proposed to solve the problems on the part of the teachers. Also suggestions such as raising the teachers′ability of designing task, enhancing the quality of teachers′instruction, promoting teachers′ classroom management ability are offered as help to improve teachers′ ability to implement cooperative learning in English classes.

  11. An efficient block-discriminant identification of packed malware

    Indian Academy of Sciences (India)

    Smita Naval; Vijay Laxmi; Manoj Singh Gaur; P Vinod

    2015-08-01

    Advanced persistent attacks, incorporated by sophisticated malware, are on the rise against hosts, user applications and utility software. Modern malware hide their malicious payload by applying packing mechanism. Packing tools instigate code encryption to protect the original malicious payload. Packing is employed in tandem with code obfuscation/encryption/compression to create malware variants. Despite being just a variant of known malware, the packed malware invalidates the traditional signature based malware detection as packing tools create an envelope of packer code around the original base malware. Therefore, unpacking becomes a mandatory phase prior to anti-virus scanning for identifying the known malware hidden behind packing layers. Existing techniques of unpacking solutions increase execution overhead of AV scanners in terms of time. This paper illustrates an easy to use approach which works in two phases to reduce this overhead. The first phase (ESCAPE) discriminates the packed code from the native code (non-packed) by using random block entropy. The second phase (PEAL) validates inferences of ESCAPE by employing bi-classification (packed vs native) model using relevant hex byte features extracted blockwise. The proposed approach is able to shrink the overall execution time of AV scanners by filtering out native samples and avoiding excessive unpacking overhead. Our method has been evaluated against a set consisting of real packed instances of malware and benign programs.

  12. Study of vibration packing characteristics with simulated fuel particles

    International Nuclear Information System (INIS)

    This report presents the results of vibration packing experiments and computational simulations of particle compaction behavior. Both sphere and shard particles were evaluated in these works. Experiments with simulated fuel particles were conducted to investigate the factors affecting packing behavior. The factors are classified into geometrical and dynamics factors. With regard to the geometrical factors for sphere packing, the experimental results proved that the achievable packing fraction can be predicted by the equation derived by Ayer, which is relationship of inner diameter of cladding and diameters of particles. As for the dynamics factors, less vibration displacement is preferable, because it produces faster packing with less segregation. Similar experiments were conducted for the shard particles. The results indicate the packing characteristics of the shard particles are different from those of the sphere particles. Optimum weight ratio between particle sizes is different from the ratio given by Ayer's equation. As for the dynamics factors, the sweeping frequencies while packing were sufficient to obtain high packing fraction. Computational simulations were performed to investigate the particle behavior during packing. The movement of infiltrating and bed particles during packing was well understood. (author)

  13. Wolves adapt territory size, not pack size to local habitat quality.

    Science.gov (United States)

    Kittle, Andrew M; Anderson, Morgan; Avgar, Tal; Baker, James A; Brown, Glen S; Hagens, Jevon; Iwachewski, Ed; Moffatt, Scott; Mosser, Anna; Patterson, Brent R; Reid, Douglas E B; Rodgers, Arthur R; Shuter, Jen; Street, Garrett M; Thompson, Ian D; Vander Vennen, Lucas M; Fryxell, John M

    2015-09-01

    1. Although local variation in territorial predator density is often correlated with habitat quality, the causal mechanism underlying this frequently observed association is poorly understood and could stem from facultative adjustment in either group size or territory size. 2. To test between these alternative hypotheses, we used a novel statistical framework to construct a winter population-level utilization distribution for wolves (Canis lupus) in northern Ontario, which we then linked to a suite of environmental variables to determine factors influencing wolf space use. Next, we compared habitat quality metrics emerging from this analysis as well as an independent measure of prey abundance, with pack size and territory size to investigate which hypothesis was most supported by the data. 3. We show that wolf space use patterns were concentrated near deciduous, mixed deciduous/coniferous and disturbed forest stands favoured by moose (Alces alces), the predominant prey species in the diet of wolves in northern Ontario, and in proximity to linear corridors, including shorelines and road networks remaining from commercial forestry activities. 4. We then demonstrate that landscape metrics of wolf habitat quality - projected wolf use, probability of moose occupancy and proportion of preferred land cover classes - were inversely related to territory size but unrelated to pack size. 5. These results suggest that wolves in boreal ecosystems alter territory size, but not pack size, in response to local variation in habitat quality. This could be an adaptive strategy to balance trade-offs between territorial defence costs and energetic gains due to resource acquisition. That pack size was not responsive to habitat quality suggests that variation in group size is influenced by other factors such as intraspecific competition between wolf packs. PMID:25757794

  14. Effective Thermal Conductivity of Adsorbent Packed Beds

    Science.gov (United States)

    Mori, Hideo; Hamamoto, Yoshinori; Yoshida, Suguru

    The effective thermal conductivity of adsorbent packed beds of granular zeolite 13X and granular silica gel A in the presence of stagnant steam or air was measured under different conditions of the adsorbent bed temperature, particle size and filler-gas pressure. The measured effective thermal conductivity showed to become smaller with decreasing particle size or decreasing pressure, but it was nearly independent of the bed temperature. When steam was the filler-gas, the rise in the thermal conductivity of the adsorbent particles due to steam adsorption led to the increase in the effective thermal conductivity of the bed, and this effect was not negligible at high steam pressure for the bed of large particle size. It was found that both the predictions of the effective thermal conductivity by the Hayashi et al.'s model and the Bauer-Schlünder model generally agreed well with the measurements, by considering the particle thermal conductivity rise due to steam adsorption. The thermal conductivity of a consolidated bed of granular zeolite 13X was also measured, and it was found to be much larger than that of the packed bed especially at lower pressure. The above prediction models underestimated the effective thermal conductivity of the consolidated bed.

  15. Class distinction

    Science.gov (United States)

    White, M. Catherine

    Typical 101 courses discourage many students from pursuing higher level science and math courses. Introductory classes in science and math serve largely as a filter, screening out all but the most promising students, and leaving the majority of college graduates—including most prospective teachers—with little understanding of how science works, according to a study conducted for the National Science Foundation. Because few teachers, particularly at the elementary level, experience any collegiate science teaching that stresses skills of inquiry and investigation, they simply never learn to use those methods in their teaching, the report states.

  16. A new approach to: (a) grid generation for numerical optimization, and (b) interconnect networks for beowulf clusters, leveraging n-dimensional sphere-packings

    Science.gov (United States)

    Bewley, Thomas; Cessna, Joseph; Belitz, Paul

    2008-11-01

    The abstract field of n-dimensional sphere packing theory is well developed (for a comprehensive review, see Sphere Packings, Lattices and Groups by Conway and Sloane). This theory forms the theoretical underpinning of the error-correcting codes used in both deep space communications and in computer memory. The present work extends this elegant theory to two important and immensely practical problems in computational fluid dynamics: (a) the generation of efficient grids for the coordination of grid-based derivative-free optimization algorithms in n dimensions, and (b) the effective n-dimensional interconnection of massively-parallel clusters of computational nodes. As we will illustrate and quantify, the first problem benefits tremendously from dense sphere packings with large kissing numbers >> 2n, whereas the latter problem benefits tremendously from rare sphere packings with kissing number = n+1.

  17. 五年制英语课堂纪律和管理问题的行动研究%An action research project on discipline and management problems of English class in five-year college

    Institute of Scientific and Technical Information of China (English)

    杨文新

    2016-01-01

    Five-year college students’misconducts on discipline often influence the atmosphere and quality of classroom, the teaching schedule and the emotions of teacher and student. How to carry out the discipline intervention and management ef-fectively has become a key and difficult point in the normal teaching,the harmonious classroom or win- win classroom. To solve the problem,the essay starts an action research in English class for more than a year with barrier strategy,trying to find out the effective ways.%五年制学生的不良纪律问题常常影响课堂风气、课堂质量、教学进度和师生之间的情感。对这些学生如何实施纪律干预以及有效管理成为正常教学、和谐课堂亦或双赢课堂的一个重点和难点。针对这个问题,采用边界策略在英语课堂上开展了为期一年多的行动研究,试图寻求有效地解决方案。

  18. A SEQUENTIAL DELIMITATIVE AND COMBINATORIAL ALGORITHM FOR A CLASS OF INTEGER PROGRAMMING PROBLEMS%求解一类整数规划问题的序列定界组合算法

    Institute of Scientific and Technical Information of China (English)

    石连拴; 柴山

    2000-01-01

    文首先提出了二维组合的定义及其生成算法,并将定界组合算法推广到 设计变量可以取任意多个整数值的情形,采用多级字典序的生成算法,按目标函数 的一定排列顺序有规律地生成所有组合,在生成组合的过程中,采用序列定界组合 算法有效地删除绝大多数非可行组合和非最优组合,大大地减少了搜索组合的个 数,具有比较高的计算效率.%In this paper,an algorithm is given for solving a class of integer programming problems. This algorithm generates all combinations of objective functions in a certain magnitude order,using a multi-level generating method of preceding for high place. In the course of combination generation ,the algorithm eliminates a iarge number of infeasible and non-optimal combinations by use of the sequen tial delimitative and combinatorial method. As a result,a higher computational efficiency is achieved.

  19. Problems in the Merged Class of University Ideological and Political Theory Course and the Countermeasures%高校思政课合班上课存在的问题和解决对策

    Institute of Scientific and Technical Information of China (English)

    卢粉艳; 赵雪红

    2012-01-01

    高校思想政治理论课合班上课存在着学生到课率低,内容入脑少,教师教学组织困难,多种教学方法无法开展,教学效果不理想等问题.为此,必须采取必要措施,加强学生管理,提高教师理论水平,加强师生双向交流,同时适当增加实践性教学环节.%There are many problems in the merged class of university ideological and political theory course, I.e. The attendance rate of students is low, the contents students grasp are little, teachers' organizational teaching is difficulty, a variety of teaching methods are unable to carry out, and teaching effect is not satisfactory. Based on this, we must strengthen students' management, improve teachers' theoretical level, strengthen two-way communication between teachers and students and increase the practical teaching links properly.

  20. Simulation of abuse tolerance of lithium-ion battery packs

    Science.gov (United States)

    Spotnitz, Robert M.; Weaver, James; Yeduvaka, Gowri; Doughty, D. H.; Roth, E. P.

    A simple approach for using accelerating rate calorimetry data to simulate the thermal abuse resistance of battery packs is described. The thermal abuse tolerance of battery packs is estimated based on the exothermic behavior of a single cell and an energy balance than accounts for radiative, conductive, and convective heat transfer modes of the pack. For the specific example of a notebook computer pack containing eight 18650-size cells, the effects of cell position, heat of reaction, and heat-transfer coefficient are explored. Thermal runaway of the pack is more likely to be induced by thermal runaway of a single cell when that cell is in good contact with other cells and is close to the pack wall.

  1. Physics based modeling of a series parallel battery pack for asymmetry analysis, predictive control and life extension

    Science.gov (United States)

    Ganesan, Nandhini; Basu, Suman; Hariharan, Krishnan S.; Kolake, Subramanya Mayya; Song, Taewon; Yeo, Taejung; Sohn, Dong Kee; Doo, Seokgwang

    2016-08-01

    Lithium-Ion batteries used for electric vehicle applications are subject to large currents and various operation conditions, making battery pack design and life extension a challenging problem. With increase in complexity, modeling and simulation can lead to insights that ensure optimal performance and life extension. In this manuscript, an electrochemical-thermal (ECT) coupled model for a 6 series × 5 parallel pack is developed for Li ion cells with NCA/C electrodes and validated against experimental data. Contribution of the cathode to overall degradation at various operating conditions is assessed. Pack asymmetry is analyzed from a design and an operational perspective. Design based asymmetry leads to a new approach of obtaining the individual cell responses of the pack from an average ECT output. Operational asymmetry is demonstrated in terms of effects of thermal gradients on cycle life, and an efficient model predictive control technique is developed. Concept of reconfigurable battery pack is studied using detailed simulations that can be used for effective monitoring and extension of battery pack life.

  2. A Comparative Study of Septoplasty With or Without Nasal Packing

    OpenAIRE

    Walikar, Basavaraj N.; Rashinkar, S. M.; Watwe, M. V.; Fathima, Anees; Kakkeri, Ashfak

    2011-01-01

    This study was conducted to compare the outcome of septoplasty with or without Nasal packing. The study subjects were randomly allocated into two groups. There was significant reduction in frequency of post operative pain, headache, discomfort and duration of hospital stay in patients who have undergone septoplasty without nasal packing. However there was no difference in post operative bleeding and septal perforation between two groups. Therefore after Septoplasty without nasal packing is pr...

  3. Low density gravel substitute gravel pack in Marlim

    Energy Technology Data Exchange (ETDEWEB)

    Albino, E.

    1996-12-31

    Successful gravel pack completion means optimization of production. This has been PETROBRAS` task regarding completion of the giant Marlim field. Significant improvement have been noticed recently with the introduction of techniques such as horizontal drilling, frac pack and low density gravel substitute gravel pack. This paper discusses the introduction and results of the system, its advantages and trends since this technique can become an excellent alternative when a more aggressive technique is no economical. (author). 5 refs., 4 figs.

  4. Extended Kalman Filter with a Fuzzy Method for Accurate Battery Pack State of Charge Estimation

    OpenAIRE

    Saeed Sepasi; Leon R. Roose; Marc M. Matsuura

    2015-01-01

    As the world moves toward greenhouse gas reduction, there is increasingly active work around Li-ion chemistry-based batteries as an energy source for electric vehicles (EVs), hybrid electric vehicles (HEVs) and smart grids. In these applications, the battery management system (BMS) requires an accurate online estimation of the state of charge (SOC) in a battery pack. This estimation is difficult, especially after substantial battery aging. In order to address this problem, this paper utilizes...

  5. Optimal Partitioned Cyclic Difference Packings for Frequency Hopping and Code Synchronization

    CERN Document Server

    Chee, Yeow Meng; Yin, Jianxing

    2010-01-01

    Optimal partitioned cyclic difference packings (PCDPs) are shown to give rise to optimal frequency-hopping sequences and optimal comma-free codes. New constructions for PCDPs, based on almost difference sets and cyclic difference matrices, are given. These produce new infinite families of optimal PCDPs (and hence optimal frequency-hopping sequences and optimal comma-free codes). The existence problem for optimal PCDPs in ${\\mathbb Z}_{3m}$, with $m$ base blocks of size three, is also solved for all $m\

  6. Human Error in Throat Pack Management: Report of Two Cases.

    Science.gov (United States)

    Baranger, Violaine; Bon Mardion, Nicolas; Dureuil, Bertrand; Compère, Vincent

    2016-06-15

    Throat packs are frequently used after tracheal intubation during ear, nose, and throat surgery. We report 2 cases of complications related to throat packs retained at the end of surgery. Miscommunication between anesthesiology and surgery teams on throat pack management led to an upper gastrointestinal endoscopy examination under general anesthesia in the first case and to severe respiratory distress requiring tracheal reintubation in the second case. Our 2 case reports highlight the importance of good communication between anesthesiology and surgery teams and of standardized procedures and checklists for the management of throat packs to ensure patient safety. PMID:27301056

  7. Multilayer DNA Origami Packed on Hexagonal and Hybrid Lattices

    DEFF Research Database (Denmark)

    Ke, Yonggang; Voigt, Niels Vinther; Shih, William M.;

    2012-01-01

    . Here we report successful folding of multilayer DNA origami with helices arranged on a close-packed hexagonal lattice. This arrangement yields a higher density of helical packing and therefore higher resolution of spatial addressing than has been shown previously. We also demonstrate hybrid multilayer...... DNA origami with honeycomb-lattice, square-lattice, and hexagonal-lattice packing of helices all in one design. The availability of hexagonal close-packing of helices extends our ability to build complex structures using DNA nanotechnology....

  8. Packed bed carburization of tantalum and tantalum alloy

    Science.gov (United States)

    Lopez, Peter C.; Rodriguez, Patrick J.; Pereyra, Ramiro A.

    1999-01-01

    Packed bed carburization of a tantalum or tantalum alloy object. A method for producing corrosion-resistant tantalum or tantalum alloy objects is described. The method includes the steps of placing the object in contact with a carburizing pack, heating the packed object in vacuum furnace to a temperature whereby carbon from the pack diffuses into the object forming grains with tantalum carbide along the grain boundaries, and etching the surface of the carburized object. This latter step removes tantalum carbides from the surface of the carburized tantalum object while leaving the tantalum carbide along the grain boundaries.

  9. Pressure-flow relationships for packed beds of compressible chromatography media at laboratory and production scale.

    Science.gov (United States)

    Stickel, J J; Fotopoulos, A

    2001-01-01

    Pressure drop across chromatography beds employing soft or semirigid media can be a significant problem in the operation of large-scale preparative chromatography columns. The shape or aspect ratio (length/diameter) of a packed bed has a significant effect on column pressure drop due to wall effects, which can result in unexpectedly high pressures in manufacturing. Two types of agarose-based media were packed in chromatography columns at various column aspect ratios, during which pressure drop, bed height, and flow rate were carefully monitored. Compression of the packed beds with increasing flow velocities was observed. An empirical model was developed to correlate pressure drop with the aspect ratio of the packed beds and the superficial velocity. Modeling employed the Blake-Kozeny equation in which empirical relationships were used to predict bed porosity as a function of aspect ratio and flow velocity. Model predictions were in good agreement with observed pressure drops of industrial scale chromatography columns. A protocol was developed to predict compression in industrial chromatography applications by a few laboratory experiments. The protocol is shown to be useful in the development of chromatographic methods and sizing of preparative columns.

  10. Generating Functionals of Random Packing Point Processes: From Hard-Core to Carrier Sensing

    CERN Document Server

    Viet, Nguyen Tien

    2012-01-01

    In this paper we study the generating functionals of several models of random packing processes: the classical Mat\\'ern hard-core model; its extensions, the $k$-Mat\\'ern models and the $\\infty$-Mat\\'ern model, which is an example of random sequential packing process. The main new results are: 1) a sufficient condition for the $\\infty$-Mat\\'ern model to be well-defined (unlike the other two, the $\\infty$-Mat\\'ern model may not be well-defined on unbounded spaces); 2) the generating functional of the resulting point process which is given for each of the three models as the solution of a differential equation; 3) series representations and bounds on the generating functional of the packing models; 4) moment measures and other useful properties of the considered packing models which are derived from their generating functionals. These results are applied to various stochastic geometry problems and in particular to the modeling and the analysis of a wireless Carrier Sensing Multiple Access network.

  11. Dynamic Lot Sizing Problem of Production and Outsourcing under the Environment of Different Customer Classes%不同顾客环境下生产及外包的动态批量问题

    Institute of Scientific and Technical Information of China (English)

    徐娟; 汪小京; 刘志学

    2014-01-01

    This paper considers a dynamic lot sizing problem of production and outsourcing with different kinds of customer class (e.g.,high valuable and low valuable one) demand in a finite time horizon.The firm can produce in house or outsourcing from outside in order to satisfy different customer demand,and then five service policies are obtained.The optimal outsourcing policy does not necessarily satisfy the Zero-Inventory-Outsourcing rule,and the optimal production policy does not necessarily satisfy the Zero-Inventory-Production rule.However,the set of production periods for high valuable customer must include the set for low valuable one.Based on this lemma,a polynomial algorithm is proposed to search out the optimal production and outsourcing policy,with time complexity O(N3),and a numeric example is given to illustrate the five service policies.At last,when the number of customer classes is larger,two heuristics are designed according to the special production and outsourcing rule.%在有限计划期内,考虑不同顾客(例如:高端和低端顾客)具有不同的缺货等待成本,企业可以采用生产或者外包的方式满足不同顾客需求.在生产和外包两种策略下,企业有五种不同的服务方式,而最优外包期不一定满足“零库存外包”规则,最优生产期不一定满足“零库存生产”规则,但满足高端顾客需求的生产期必须包含满足低端顾客需求的生产期.基于此性质,提出了一个多项式算法得到最优的生产及外包策略,并为每类顾客制定相应的服务策略,计算复杂度为O(N3),并通过算例分析了五种不同的服务策略.最后,拓展到多类顾客的需求环境,根据特殊的生产法则和顾客分类方法,分别设计了一种启发式算法,得到企业的生产及外包策略.

  12. Python Classes for Numerical Solution of PDE's

    CERN Document Server

    Mushtaq, Asif; Olaussen, Kåre

    2015-01-01

    We announce some Python classes for numerical solution of partial differential equations, or boundary value problems of ordinary differential equations. These classes are built on routines in \\texttt{numpy} and \\texttt{scipy.sparse.linalg} (or \\texttt{scipy.linalg} for smaller problems).

  13. Hyperstaticity and loops in frictional granular packings

    Science.gov (United States)

    Tordesillas, Antoinette; Lam, Edward; Metzger, Philip T.

    2009-06-01

    The hyperstatic nature of granular packings of perfectly rigid disks is analyzed algebraically and through numerical simulation. The elementary loops of grains emerge as a fundamental element in addressing hyperstaticity. Loops consisting of an odd number of grains behave differently than those with an even number. For odd loops, the latent stresses are exterior and are characterized by the sum of frictional forces around each loop. For even loops, the latent stresses are interior and are characterized by the alternating sum of frictional forces around each loop. The statistics of these two types of loop sums are found to be Gibbsian with a "temperature" that is linear with the friction coefficient μ when μ<1.

  14. Regulation relative to the packing and packing wastes; Reglementation relative aux emballages et dechets d'emballages

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-08-01

    The objectives of the european directive 94/62/CE of the 20 december 1994, relative to the packing and the packing wastes, are the harmonization between the States members, the environment protection and a management of the internal market in agreement with the Treaty. This text recalls the regulations in the french domain. Industrial and municipal packings wastes are concerned. (A.L.B.)

  15. Volatile compounds and odor preferences of ground beef added with garlic and red wine, and irradiated with charcoal pack

    International Nuclear Information System (INIS)

    Irradiation is the most efficient non-thermal technology for improving hygienic quality and extending the shelf-life of food products. One of the adverse effects of food irradiation, however, is off-flavor production, which significantly affects the sensory preferences for certain foods. In this study, garlic (5%, w/w) and red wine (1:1, w/w) were added to ground beef to increase the radiation sensitivity of pathogens and improve meat odor/flavor. Samples were irradiated at 0 or 5 kGy in the presence of charcoal pack. SPME-GC–MS analysis was performed to measure the changes in the volatile compounds and sensory characteristics of the samples. The amount of total volatile compounds produced from ground beef was greater when the sample was irradiated. When garlic and red wine were added to the ground beef, the amount of volatile compounds significantly increased, and the amount of volatile compounds increased even further after irradiation. However, when the samples were irradiated with charcoal pack, the amount of volatile compounds decreased significantly. Sensory evaluation indicated that charcoal pack significantly increased the odor preferences for both irradiated and non-irradiated ground beef added with garlic. These results indicated that addition of charcoal pack to ground beef could reduce off-odor problems induced by irradiation, and this effect was consistent even when certain additives such as garlic and red wine were added. - Highlights: ► Garlic and red wine were added to ground beef and irradiated at 5 kGy in the presence of charcoal pack. ► When the samples were irradiated with charcoal pack, the amount of volatile compounds decreased significantly and it affected sensory score. ► Thus, addition of charcoal pack to ground beef could reduce off-odor problems induced by irradiation. ► This effect was consistent when additives, such as garlic and red wine, were added into ground beef.

  16. Optical anisotropy in packed isotropic spherical particles: indication of nanometer scale anisotropy in packing structure.

    Science.gov (United States)

    Yamaguchi, Kohei; Inasawa, Susumu; Yamaguchi, Yukio

    2013-02-28

    We investigated the origin of birefringence in colloidal films of spherical silica particles. Although each particle is optically isotropic in shape, colloidal films formed by drop drying demonstrated birefringence. While periodic particle structures were observed in silica colloidal films, no regular pattern was found in blended films of silica and latex particles. However, since both films showed birefringence, regular film structure patterns were not required to exhibit birefringence. Instead, we propose that nanometer-scale film structure anisotropy causes birefringence. Due to capillary flow from the center to the edge of a cast suspension, particles are more tightly packed in the radial direction. Directional packing results in nanometer-scale anisotropy. The difference in the interparticle distance between radial and circumferential axes was estimated to be 10 nm at most. Nanometer-scale anisotropy in colloidal films and the subsequent optical properties are discussed.

  17. New series of paper pack vending machines; Paper pack jido hanbaiki no shin series

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, M. [Fuji Denki Reiki Co. Ltd., Tokyo (Japan); Umino, S. [Fuji Electric Co. Ltd., Tokyo (Japan)

    1996-07-10

    This paper presents series of paper pack vending machines. These machines may be broadly classified into those of cold drinks and of hot and cold drinks depending on the storage temperature of products. The former is the machine for cooling dairy products at 10{degree}C with a combined stacking by direct-stacked racks and chain-multiracks. The latter is provided with divided storing chambers with each chamber selectively cooled or heated. Products in the hot chamber are canned coffee and the like set at 55{degree}C. The temperature control is performed by a microcomputer. The chain-multiracks are provided with advantages such as capability of handling various kinds of container shapes, storing drinks and foods vertically, replacing products by the change of a shelf attachment with one operation, and storing one liter packs by setting pair columns. The direct-stacked racks are provided with advantages such as versatility of handling various kinds of containers and miniaturization of the mechanism other than the storage part. The installation space was reduced by devising the opening and closing of the door. The control part is capable of setting temperatures differently for cans and paper packs. 7 figs., 1 tab.

  18. The Performance of Structured Packings in Trickle-Bed Reactors

    NARCIS (Netherlands)

    Frank, M.J.W.; Kuipers, J.A.M.; Versteeg, G.F.; Swaaij, W.P.M. van

    1999-01-01

    An experimental study was carried out to investigate whether the use of structured packings might improve the mass transfer characteristics and the catalyst effectiveness of a trickle-bed reactor. Therefore, the performances of a structured packing, consisting of KATAPAK elements, and a dumped packi

  19. The performance of structured packings in trickle-bed reactors.

    NARCIS (Netherlands)

    Frank, M.J.W.; Kuipers, J.A.M.; Versteeg, G.F.; Swaaij, van W.P.M.

    1999-01-01

    An experimental study was carried out to investigate whether the use of structured packings might improve the mass transfer characteristics and the catalyst effectiveness of a trickle-bed reactor. Therefore, the performances of a structured packing, consisting of KATAPAK elements, and a dumped packi

  20. Hydrodynamics of multi-phase packed bed micro-reactors

    NARCIS (Netherlands)

    Márquez Luzardo, N.M.

    2010-01-01

    Why to use packed bed micro-reactors for catalyst testing? Miniaturized packed bed reactors have a large surface-to-volume ratio at the reactor and particle level that favors the heat- and mass-transfer processes at all scales (intra-particle, inter-phase and inter-particle or reactor level). If the

  1. 48 CFR 552.211-75 - Preservation, Packaging and Packing.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Preservation, Packaging....211-75 Preservation, Packaging and Packing. As prescribed in 511.204(b)(2), insert the following clause: Preservation, Packaging, and Packing (FEB 1996) Unless otherwise specified, all items shall...

  2. Experimental validation of packed bed chemical-looping combustion

    NARCIS (Netherlands)

    Noorman, S.; Sint Annaland, van M.; Kuipers, J.A.M.

    2010-01-01

    Chemical-looping combustion has emerged as a promising alternative technology, intrinsically integrating CO2 capture in power production. A novel reactor concept based on dynamically operated packed beds has been proposed [Noorman, S., van Sint Annaland, M., Kuipers, J.A.M., 2007. Packed bed reactor

  3. Predicting the Liquid Phase Mass Transfer Resistance of Structured Packings

    NARCIS (Netherlands)

    Olujic, Z.; Seibert, A.F.

    2014-01-01

    Published correlations for estimating the liquid phase mass transfer coefficients of structured packings are compared using experimental evidence on the efficiency of Montz-Pak B1–250MN and B1–500MN structured packings as measured in total reflux distillation tests using the chlorobenzene/ethylbenze

  4. 48 CFR 852.214-73 - Alternate packaging and packing.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Alternate packaging and....214-73 Alternate packaging and packing. As prescribed in 814.201-6(b)(3), insert the following provision: Alternate Packaging and Packing (JAN 2008) The bidder's offer must clearly indicate the...

  5. A relationship between maximum packing of particles and particle size

    Science.gov (United States)

    Fedors, R. F.

    1979-01-01

    Experimental data indicate that the volume fraction of particles in a packed bed (i.e. maximum packing) depends on particle size. One explanation for this is based on the idea that particle adhesion is the primary factor. In this paper, however, it is shown that entrainment and immobilization of liquid by the particles can also account for the facts.

  6. A selection-quotient process for packed word Hopf algebra

    CERN Document Server

    Duchamp, G H E; Tanasa, A

    2013-01-01

    In this paper, we define a Hopf algebra structure on the vector space spanned by packed words using a selection-quotient coproduct. We show that this algebra is free on its irreducible packed words. Finally, we give some brief explanations on the Maple codes we have used.

  7. 76 FR 251 - Country of Origin Labeling of Packed Honey

    Science.gov (United States)

    2011-01-04

    ... final rule published in the Federal Register on July 8, 2009 (74 FR 32389) to include provisions for... Service 7 CFR Part 52 RIN 0581-AC89 Country of Origin Labeling of Packed Honey AGENCY: Agricultural..., establishing new regulations addressing country of origin labeling for packed honey bearing any official...

  8. Does the fluid elasticity influence the dispersion in packed beds?

    NARCIS (Netherlands)

    Westerterp, K. Roel; Wijngaarden, Ruud J.; Nijhuis, Niek B.G.

    1996-01-01

    Reasons are given why the axial dispersion in a gas flowing through a packed bed may be influenced by the elasticity - or compressibility - of the fluid. To support this hypothesis, experiments have been done in a packed column at pressures from 0.13 to 2.0 MPa. The elasticity E of a gas is proporti

  9. Growth of Vanadium Carbide by Halide-Activated Pack Diffusion

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Dahl, Kristian Vinter;

    The present work investigates growth of vanadium carbide (VC) layers by the pack diffusion method on a Vanadis 6 tool steel. The VC layers were produced by pack diffusion at 1000°C for 1, 4 and 16 hours. The VC layers were characterized with optical and electron microscopy, Vickers hardness tests...

  10. The effect of nanoparticle packing on capacitive electrode performance

    Science.gov (United States)

    Lee, Younghee; Noh, Seonmyeong; Kim, Min-Sik; Kong, Hye Jeong; Im, Kyungun; Kwon, Oh Seok; Kim, Sungmin; Yoon, Hyeonseok

    2016-06-01

    Nanoparticles pack together to form macro-scale electrodes in various types of devices, and thus, optimization of the nanoparticle packing is a prerequisite for the realization of a desirable device performance. In this work, we provide in-depth insight into the effect of nanoparticle packing on the performance of nanoparticle-based electrodes by combining experimental and computational findings. As a model system, polypyrrole nanospheres of three different diameters were used to construct pseudocapacitive electrodes, and the performance of the electrodes was examined at various nanosphere diameter ratios and mixed weight fractions. Two numerical algorithms are proposed to simulate the random packing of the nanospheres on the electrode. The binary nanospheres exhibited diverse, complicated packing behaviors compared with the monophasic packing of each nanosphere species. The packing of the two nanosphere species with lower diameter ratios at an optimized composition could lead to more dense packing of the nanospheres, which in turn could contribute to better device performance. The dense packing of the nanospheres would provide more efficient transport pathways for ions because of the reduced inter-nanosphere pore size and enlarged surface area for charge storage. Ultimately, it is anticipated that our approach can be widely used to define the concept of ``the best nanoparticle packing'' for desirable device performance.Nanoparticles pack together to form macro-scale electrodes in various types of devices, and thus, optimization of the nanoparticle packing is a prerequisite for the realization of a desirable device performance. In this work, we provide in-depth insight into the effect of nanoparticle packing on the performance of nanoparticle-based electrodes by combining experimental and computational findings. As a model system, polypyrrole nanospheres of three different diameters were used to construct pseudocapacitive electrodes, and the performance of the

  11. Packing fraction of particles with lognormal size distribution.

    Science.gov (United States)

    Brouwers, H J H

    2014-05-01

    This paper addresses the packing and void fraction of polydisperse particles with a lognormal size distribution. It is demonstrated that a binomial particle size distribution can be transformed into a continuous particle-size distribution of the lognormal type. Furthermore, an original and exact expression is derived that predicts the packing fraction of mixtures of particles with a lognormal distribution, which is governed by the standard deviation, mode of packing, and particle shape only. For a number of particle shapes and their packing modes (close, loose) the applicable values are given. This closed-form analytical expression governing the packing fraction is thoroughly compared with empirical and computational data reported in the literature, and good agreement is found.

  12. A COMPARATIVE STUDY OF SEPTOPLASTY WITH OR WITHOUT NASAL PACKING: OUR EXPERIENCE IN TERTIARY CARE HOSPITAL

    Directory of Open Access Journals (Sweden)

    Mylanahalli Doddarangaiah

    2016-05-01

    Full Text Available BACKGROUND Deflected nasal septum (DNS is the commonest septal problem in ENT practice. The most painful and unpleasant part of this procedure is during removal of nasal pack. AIM Our study aims to compare the results of septoplasty with and without post-operative nasal packing and thereby assess the necessity of nasal packing after septoplasty in terms of patient’s comfort, effectiveness at controlling the haemorrhage. METHODOLOGY In our study, 80 patients who underwent septoplasty in our institution during the period July 2014 till April 2015 were simply randomised into two groups, 1 group received post-operative packing and for the other group of 40 patients, nasal packing was not done and their symptoms assessed and compared on post-operative day 1, after 1 week and 1 month and results were analysed. The following symptoms nasal obstruction, headache, bleeding, irritation of eyes, mouth breathing, running nose, ear ache, fullness, disturbed sleep, loss of smell or taste and crusting were assessed. Patients who underwent septoplasty with turbinectomy or MMA or FESS were excluded from the study. RESULTS Among the 80 patients who participated in the study, predominant were males (67.5% and the predominant age group was 11-20 years. On comparing the nasal symptoms on post-operative day 1, there was significant difference between the study and control groups in the symptoms, headache, nasal obstruction, irritation/watering of eyes, mouth breathing, earache, ear fullness, disturbed sleep, loss of smell/taste, crusting, showed statistically significant difference among both the groups whereas bleeding, nasal discharge were not significant. On comparing the symptoms after one week, nasal obstruction, mouth breathing, crusting and loss of smell had statistically significant values and bleeding and irritation of eyes were not present in both the groups. After one month when the symptoms were compared, none of them were statistically significant

  13. On fully packed loop configurations with four sets of nested arches

    Science.gov (United States)

    Di Francesco, P.; Zuber, J.-B.

    2004-06-01

    The problem of counting the number of fully packed loop (FPL) configurations with four sets of a, b, c, d nested arches is addressed. It is shown that it may be expressed as the problem of enumeration of tilings of a domain of the triangular lattice with a conic singularity. After re-expression in terms of non-intersecting lines, the Lindström-Gessel-Viennot theorem leads to a formula as a sum of determinants. This is made quite explicit when min(a, b, c, d) = 1 or 2. We also find a compact determinant formula which generates the numbers of configurations with b = d.

  14. Packing regularities in biological structures relate to their dynamics.

    Science.gov (United States)

    Jernigan, Robert L; Kloczkowski, Andrzej

    2007-01-01

    The high packing density inside proteins leads to certain geometric regularities and also is one of the most important contributors to the high extent of cooperativity manifested by proteins in their cohesive domain motions. The orientations between neighboring nonbonded residues in proteins substantially follow the similar geometric regularities, regardless of whether the residues are on the surface or buried, a direct result of hydrophobicity forces. These orientations are relatively fixed and correspond closely to small deformations from those of the face-centered cubic lattice, which is the way in which identical spheres pack at the highest density. Packing density also is related to the extent of conservation of residues, and we show this relationship for residue packing densities by averaging over a large sample or residue packings. There are three regimes: (1) over a broad range of packing densities the relationship between sequence entropy and inverse packing density is nearly linear, (2) over a limited range of low packing densities the sequence entropy is nearly constant, and (3) at extremely low packing densities the sequence entropy is highly variable. These packing results provide important justification for the simple elastic network models that have been shown for a large number of proteins to represent protein dynamics so successfully, even when the models are extremely coarse grained. Elastic network models for polymeric chains are simple and could be combined with these protein elastic networks to represent partially denatured parts of proteins. Finally, we show results of applications of the elastic network model to study the functional motions of the ribosome, based on its known structure. These results indicate expected correlations among its components for the step-wise processing steps in protein synthesis, and suggest ways to use these elastic network models to develop more detailed mechanisms, an important possibility because most

  15. SEPTOPLASTY WITH AND WITHOUT NASAL PACKING: A COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Mitta

    2016-05-01

    Full Text Available Septoplasty is one of the most commonly performed surgeries in rhinology to relieve nasal obstruction of patients with distortion in the midline cartilage or septum of the nose to relieve nasal obstruction of patient and findings consistent with nasal endoscopy. The anterior nasal packing routinely done following septoplasty is usually conventional and not evidence based. The purpose of nasal packing is to obtain haemostasis, enhance opposition of septal flaps, avoid septal haematoma formation, close the dead space, avoid synechiae formation, provide support to septal cartilage and prevent its displacement. OBJECTIVE This study intends to evaluate the effects of nasal packing on surgical success and related complications in septoplasty. MATERIALS AND METHODS The present clinical prospective and randomised study was carried out on patients attending Otorhinolaryngology Department of Santhiram Medical College & General Hospital between March 2012 and March 2015. Patients undergoing septoplasty were randomised either to receive anterior nasal packing or to not receive nasal packing postoperatively. RESULTS Levels of pain experienced by patients with nasal packing postoperatively during the initial 24 hours postoperatively and during the removal of the pack were significantly more. Post-operative headache, epiphora, swallowing discomfort and sleep disturbance were more in patients with nasal packing and statistically (p.05. Septal haematoma, adhesions and local infections in both groups were statistically insignificant (p>.05. CONCLUSION Septoplasty enhances the standard of living of patients with septal deviation and nasal obstruction. Our study results suggest that nasal packing after septoplasty is not obligatory. Nasal packing causes considerably more pain and complications, and it should be reserved only for those who have bleeding predisposition.

  16. Differential equations problem solver

    CERN Document Server

    Arterburn, David R

    2012-01-01

    REA's Problem Solvers is a series of useful, practical, and informative study guides. Each title in the series is complete step-by-step solution guide. The Differential Equations Problem Solver enables students to solve difficult problems by showing them step-by-step solutions to Differential Equations problems. The Problem Solvers cover material ranging from the elementary to the advanced and make excellent review books and textbook companions. They're perfect for undergraduate and graduate studies.The Differential Equations Problem Solver is the perfect resource for any class, any exam, and

  17. Too packed to change: side-chain packing and site-specific substitution rates in protein evolution

    Directory of Open Access Journals (Sweden)

    María Laura Marcos

    2015-04-01

    Full Text Available In protein evolution, due to functional and biophysical constraints, the rates of amino acid substitution differ from site to site. Among the best predictors of site-specific rates are solvent accessibility and packing density. The packing density measure that best correlates with rates is the weighted contact number (WCN, the sum of inverse square distances between a site’s Cα and the Cα of the other sites. According to a mechanistic stress model proposed recently, rates are determined by packing because mutating packed sites stresses and destabilizes the protein’s active conformation. While WCN is a measure of Cα packing, mutations replace side chains. Here, we consider whether a site’s evolutionary divergence is constrained by main-chain packing or side-chain packing. To address this issue, we extended the stress theory to model side chains explicitly. The theory predicts that rates should depend solely on side-chain contact density. We tested this prediction on a data set of structurally and functionally diverse monomeric enzymes. We compared side-chain contact density with main-chain contact density measures and with relative solvent accessibility (RSA. We found that side-chain contact density is the best predictor of rate variation among sites (it explains 39.2% of the variation. Moreover, the independent contribution of main-chain contact density measures and RSA are negligible. Thus, as predicted by the stress theory, site-specific evolutionary rates are determined by side-chain packing.

  18. Too packed to change: side-chain packing and site-specific substitution rates in protein evolution.

    Science.gov (United States)

    Marcos, María Laura; Echave, Julian

    2015-01-01

    In protein evolution, due to functional and biophysical constraints, the rates of amino acid substitution differ from site to site. Among the best predictors of site-specific rates are solvent accessibility and packing density. The packing density measure that best correlates with rates is the weighted contact number (WCN), the sum of inverse square distances between a site's C α and the C α of the other sites. According to a mechanistic stress model proposed recently, rates are determined by packing because mutating packed sites stresses and destabilizes the protein's active conformation. While WCN is a measure of C α packing, mutations replace side chains. Here, we consider whether a site's evolutionary divergence is constrained by main-chain packing or side-chain packing. To address this issue, we extended the stress theory to model side chains explicitly. The theory predicts that rates should depend solely on side-chain contact density. We tested this prediction on a data set of structurally and functionally diverse monomeric enzymes. We compared side-chain contact density with main-chain contact density measures and with relative solvent accessibility (RSA). We found that side-chain contact density is the best predictor of rate variation among sites (it explains 39.2% of the variation). Moreover, the independent contribution of main-chain contact density measures and RSA are negligible. Thus, as predicted by the stress theory, site-specific evolutionary rates are determined by side-chain packing.

  19. Packing schemes of cavities in selected clathrasils and zeolites and the analogous packings of atoms in crystal structures

    DEFF Research Database (Denmark)

    Hem, Caroline Piper; Makovicky, Emil; Balic Zunic, Tonci

    2010-01-01

    of kagome nets and its cavity packing is an analog to the packing scheme of atoms in the cubic Laves phase MgCu2. Dodecasil 1H has an arrangement of [512] cavities in an AA stacking of kagome nets and is analogous to the alloy structure type CaZn5. Edingtonite and natrolite are built from two types......, and interpreted by comparison with analogous packings of atoms in inorganic compounds and alloys. The topology is described qualitatively as “negative” structures formed by the cavities. Melanophlogite and dodecasils 3C and 1H are all clathrasils with isolated cavities. They all have pentagonal dodecahedral [512......] cages, associated with other cavity types. The packing of cavities in melanophlogite is analogous to the packing of atoms in the structure of Cr3Si, where the Cr atoms form icosahedra around the Si sites. Dodecasil 3C has a cubic arrangement of [512] cavities, which is described as ABC stacking...

  20. Generation of homogeneous granular packings: Contact dynamics method with coupling to an external pressure bath

    CERN Document Server

    Shaebani, M Reza; Kertesz, Janos

    2008-01-01

    The contact dynamics method (CD) is an efficient simulation technique of dense granular media where unilateral and frictional contact problems for a large number of rigid bodies have to be solved. In this paper we present a modified version of the contact dynamics to generate homogeneous random packings of rigid grains. CD is coupled to an external pressure bath, which allows the variation of the size of a periodically repeated cell. We follow the concept of the Andersen dynamics and show how it can be applied within the framework of the contact dynamics method. The main challenge here is to handle the interparticle interactions properly, which are based on constraint forces in CD. We implement the proposed algorithm, perform test simulations and investigate the properties of the final packings.