Heuristics for Multidimensional Packing Problems
DEFF Research Database (Denmark)
Egeblad, Jens
minimum height container required for the items. The main contributions of the thesis are three new heuristics for strip-packing and knapsack packing problems where items are both rectangular and irregular. In the two first papers we describe a heuristic for the multidimensional strip-packing problem that...... results of this heuristic are among the best published in the literature both for two- and three-dimensional strip-packing problems for irregular shapes. In the third paper, we introduce a heuristic for two- and three-dimensional rectangular knapsack packing problems. The two-dimensional heuristic uses...... promising. A heuristic for a three-dimensional knapsack packing problem involving furniture is presented in the fourth paper. The heuristic is based on a variety of techniques including tree-search, wall-building, and sequential placement. The solution process includes considerations regarding stability and...
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...
Modified strip packing heuristics for the rectangular variable-sized bin packing problem
Directory of Open Access Journals (Sweden)
FG Ortmann
2010-06-01
Full Text Available Two packing problems are considered in this paper, namely the well-known strip packing problem (SPP and the variable-sized bin packing problem (VSBPP. A total of 252 strip packing heuristics (and variations thereof from the literature, as well as novel heuristics proposed by the authors, are compared statistically by means of 1170 SPP benchmark instances in order to identify the best heuristics in various classes. A combination of new heuristics with a new sorting method yields the best results. These heuristics are combined with a previous heuristic for the VSBPP by the authors to find good feasible solutions to 1357 VSBPP benchmark instances. This is the largest statistical comparison of algorithms for the SPP and the VSBPP to the best knowledge of the authors.
On Approximating Four Covering and Packing Problems
Ashley, Mary; Berman, Piotr; Chaovalitwongse, Wanpracha; DasGupta, Bhaskar; Kao, Ming-Yang; 10.1016/j.jcss.2009.01.002
2011-01-01
In this paper, we consider approximability issues of the following four problems: triangle packing, full sibling reconstruction, maximum profit coverage and 2-coverage. All of them are generalized or specialized versions of set-cover and have applications in biology ranging from full-sibling reconstructions in wild populations to biomolecular clusterings; however, as this paper shows, their approximability properties differ considerably. Our inapproximability constant for the triangle packing problem improves upon the previous results; this is done by directly transforming the inapproximability gap of Haastad for the problem of maximizing the number of satisfied equations for a set of equations over GF(2) and is interesting in its own right. Our approximability results on the full siblings reconstruction problems answers questions originally posed by Berger-Wolf et al. and our results on the maximum profit coverage problem provides almost matching upper and lower bounds on the approximation ratio, answering a...
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....
The load-balanced multi-dimensional bin-packing problem
DEFF Research Database (Denmark)
Trivella, Alessio; Pisinger, David
2016-01-01
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...
Improved Absolute Approximation Ratios for Two-Dimensional Packing Problems
Harren, Rolf; van Stee, Rob
We consider the two-dimensional bin packing and strip packing problem, where a list of rectangles has to be packed into a minimal number of rectangular bins or a strip of minimal height, respectively. All packings have to be non-overlapping and orthogonal, i.e., axis-parallel. Our algorithm for strip packing has an absolute approximation ratio of 1.9396 and is the first algorithm to break the approximation ratio of 2 which was established more than a decade ago. Moreover, we present a polynomial time approximation scheme (mathcal{PTAS}) for strip packing where rotations by 90 degrees are permitted and an algorithm for two-dimensional bin packing with an absolute worst-case ratio of 2, which is optimal provided mathcal{P} not= mathcal{NP}.
Integrating packing and distribution problems and optimization through mathematical programming
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...
A SAT Encoding for Multi-dimensional Packing Problems
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.
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...
A Novel GRASP Algorithm for Solving the Bin Packing Problem
Directory of Open Access Journals (Sweden)
Abdesslem Layeb
2012-04-01
Full Text Available The Bin Packing Problem (BPP is one of the most known combinatorial optimization problems. This problem consists in packing 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 GRASP procedure to deal with the1-BPP problem. The first GRASP phase is based on a new random heuristics based on hybridization between First Fit and Best Fit heuristics. The second GRASP phase is based on Tabu search algorithm used for the enhancement of the solutions found in the first phase. The obtained results are very encouraging and show the feasibility and effectiveness of the proposed approach
Bin Completion Algorithms for Multicontainer Packing, Knapsack, and Covering Problems
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,...
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.
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.
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.
Solving non-standard packing problems by global optimization and heuristics
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...
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.
Performance Analysis of Selective Breeding Algorithm on One Dimensional Bin Packing Problems
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.
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.
Hybrid next-fit algorithm for the two-dimensional rectangle bin-packing problem
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
Model and algorithm for container ship stowage planning based on bin-packing problem
Institute of Scientific and Technical Information of China (English)
无
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.
Spatial Cluster Analysis by the Bin-Packing Problem and DNA Computing Technique
Xiyu Liu; Jie Xue
2013-01-01
Spatial cluster analysis is an important data mining task. Typical techniques include CLARANS, density- and gravity-based clustering, and other algorithms based on traditional von Neumann's computing architecture. The purpose of this paper is to propose a technique for spatial cluster analysis based on sticker systems of DNA computing. We will adopt the Bin-Packing Problem idea and then design algorithms of sticker programming. The proposed technique has a better time complexity. In the case ...
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.
A new class of variational equation problems
Institute of Scientific and Technical Information of China (English)
无
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.
Protein side-chain packing problem: a maximum edge-weight clique algorithmic approach.
Dukka Bahadur, K C; Tomita, Etsuji; Suzuki, Jun'ichi; Akutsu, Tatsuya
2005-02-01
"Protein Side-chain Packing" has an ever-increasing application in the field of bio-informatics, dating from the early methods of homology modeling to protein design and to the protein docking. However, this problem is computationally known to be NP-hard. In this regard, we have developed a novel approach to solve this problem using the notion of a maximum edge-weight clique. Our approach is based on efficient reduction of protein side-chain packing problem to a graph and then solving the reduced graph to find the maximum clique by applying an efficient clique finding algorithm developed by our co-authors. Since our approach is based on deterministic algorithms in contrast to the various existing algorithms based on heuristic approaches, our algorithm guarantees of finding an optimal solution. We have tested this approach to predict the side-chain conformations of a set of proteins and have compared the results with other existing methods. We have found that our results are favorably comparable or better than the results produced by the existing methods. As our test set contains a protein of 494 residues, we have obtained considerable improvement in terms of size of the proteins and in terms of the efficiency and the accuracy of prediction. PMID:15751115
Bin packing approach for solving VLSI circuit partitioning problem using Genetic algorithm
Directory of Open Access Journals (Sweden)
Prof. Sharadindu Roy
2012-12-01
Full Text Available In this paper,the circuit partitioning using genetic algorithm with bin packing concept has been attempted. In this practical paper solution is easy and we can easily apply genetic operator in this type of problem. The bin packing problem is to find the minimum number of bins needed to pack a given set of objects of known sizes so they do not exceed the capacity of each bin. Complexity is both time in space, provided size of problem an as integer (count is infinite.This problem is known NP-hard. The technique of our approach is to be design module trick. We can be realizing with self standard IC chip. Obviously we have taken into account minimum power conjunction. The solution of a circuit partitioning problem is global optimum. Like circuit partitioning is the more critical step in the physical design of various circuit in VLSI.In the partitioning main objective is to minimize the number of cuts.This chapter addresses the problem of partitioning and particular the use of the genetic algorithms for circuit partitioning.The object to be partitioned in VLSI design are typically logic gates or instances of standard cell. Circuit partitioning is one of the important parts in chip designing. We let, the number of bins will be needed equal to be number of genes divided by number of bins. At first the genes will be insert in first bin until the bin is not full, when bin is full then insert second bin and so on. Our method calculates the fitness value and discards solution with low fitness value. The increase in number of crossover point does not necessarily increase the fitness, as the fitness achieved depends on crossover as well as mutation probability. Especially in the paper find minimum cut size. If we get, cut size is same on generation than change the crossover boundary. This paper shows bin packing approach for the circuit partitioning using genetic algorithm . Genetic algorithm is an evolutionary optimization technique based on Darwinian
The CLASS system and the scheduling problem
International Nuclear Information System (INIS)
The need to process large quantities of data on the machine equipment of nuclear power plants and the high level of occurrence of recurrent technological procedures applied in maintenance will create the preconditions for the introduction of automated processing of this data and the subsequent automated control of units of centralized maintenance in nuclear power plants. For the said purposes the Research Institute for Nuclear Power Plants at Jaslovske Bohunice has selected activities suitable for automated processing and has experimentally applied to these activities the CLASS decision-making system operating with the CPM method. It is stated that the automated system for the operative control of repairs of nuclear power plants requires detailed information on conditions from which ensue the inter-relations between repairs. The choice of the most suitable sequence of operations should be left to the program which uses elements of artificial intelligence. Some aspects are discussed of the mathematical model of such a decision-making system in CLASS-AI operative control. (Z.M.)
Solving a Class of Non-Smooth Optimal Control Problems
Directory of Open Access Journals (Sweden)
M. H. Noori Skandari
2013-06-01
Full Text Available In this paper, we first propose a new generalized derivative for non-smooth functions and then we utilize this generalized derivative to convert a class of non-smooth optimal control problem to the corresponding smooth form. In the next step, we apply the discretization method to approximate the obtained smooth problem to the nonlinear programming problem. Finally, by solving the last problem, we obtain an approximate optimal solution for main problem.
Dynamic Multi-class Network Loading Problem
Institute of Scientific and Technical Information of China (English)
无
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.
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.
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.
Numerical Algorithm for a Class of Linear Fractional Programming Problem
Hongwei Jiao; Kun Li; Jianping Wang
2013-01-01
In this study, a branch and bound algorithm is presented for globally solving a class of linear fractional programming problems. In the algorithm, a linear relaxation method is introduced to generate the linear relaxation programming problem of the investigated linear fractional programming problems. In this study, we pay more attention to the numerical experiments. Several test problems are used to verify the feasibility and computational efficiency of the proposed branch and bound algorithm.
Study on the Uneven cells Problem of the Power Battery Pack in the Automotive Application by ECM
Jiayuan, Wang; Zechang, Sun; Xuezhe, Wei; Haifeng, Dai
Uneven cells problem is a universal phenomenon in the cell grouping application. It will cause performance and safety problems if the uneven is not considered during pack design and application, especially for the automotive application. The ECM model is used for the study of the uneven cells phenomenon of the power battery pack in the automotive application. An EV model and a FCV model are used for simulating the current profiles for two representative powertrain systems. The links of the ECM are set in five conditions for separate study on the impact. The results show different impact on the SOC and voltage with the same sets of links for the two powertrain model. The cell grouping design and the balance algorithm should be adjusted according to the different application background when the uneven cells problems are considered.
Minimax theory for a class of nonlinear statistical inverse problems
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.
An Evaluable Theory for a Class of Migration Problems
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...
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.
Polynomial approximations of a class of stochastic multiscale elasticity problems
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
Pelayo, Alvaro
2007-01-01
We define and solve the toric version of the symplectic ball packing problem, in the sense of listing all 2n-dimensional symplectic-toric manifolds which admit a perfect packing by balls embedded in a symplectic and torus equivariant fashion. In order to do this we first describe a problem in geometric-combinatorics which is equivalent to the toric symplectic ball packing problem. Then we solve this problem using arguments from Convex Geometry and Delzant theory. Applications to symplectic bl...
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.
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
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
Positive solutions for classes of multiparameter elliptic semipositone problems
Directory of Open Access Journals (Sweden)
Sumalee Unsurangsie
2007-06-01
Full Text Available We study positive solutions to multiparameter boundary-value problems of the form egin{gather*} - Delta u =lambda g(u+mu f(uquad ext{in } Omega \\ u =0 quad ext{on } partial Omega , end{gather*} where $lambda >0$, $mu >0$, $Omega subseteq R^{n}$; $ngeq 2$ is a smooth bounded domain with $partial Omega $ in class $C^{2}$ and $Delta $ is the Laplacian operator. In particular, we assume $g(0>0$ and superlinear while $f(0<0$, sublinear, and eventually strictly positive. For fixed $mu$, we establish existence and multiplicity for $lambda $ small, and nonexistence for $lambda $ large. Our proofs are based on variational methods, the Mountain Pass Lemma, and sub-super solutions.
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.
An evolutionary approach to the problem of three-dimensional geometric objects packing
Крижанівський, В'ячеслав Борисович; Шавурська, Ганна Павлівна
2014-01-01
A problem of optimal placement of three-dimensional geometric objects is considered. The position of geometric objects is determined by solving linear programming problems. A search in linear programming problems set is implemented using a genetic algorithm. Designed and implemented a software product that allows you to examine the behavior of genetic algorithms depending on the population size, selection operators of pair of "parents", the type of crossover, selection operator of individuals...
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.
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
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.
Minimizers of a Class of Constrained Vectorial Variational Problems: Part I
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.
Online Stochastic Packing Applied to Display Ad Allocation
Feldman, Jon; Henzinger, Monika; Korula, Nitish; Mirrokni, Vahab S.; Stein, Cliff
2010-01-01
Inspired by online ad allocation, we study online stochastic packing linear programs from theoretical and practical standpoints. We first present a near-optimal online algorithm for a general class of packing linear programs which model various online resource allocation problems including online variants of routing, ad allocations, generalized assignment, and combinatorial auctions. As our main theoretical result, we prove that a simple primal-dual training-based algorithm achieves a (1 - o(...
Optimized packings with applications
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...
Quasiperiodic packing densities
International Nuclear Information System (INIS)
The problem of the packing density on quasiperiodic lattices is discussed in a systematic way using projection techniques. For compact domains a direct construction is presented using a Voronoi construction on a quasilattice in perpendicular space defined by the forbidden volume of the packed objects. A generalized inflation law, valid for arbitrary shapes of the acceptance domain using the properties of linear mappings of the hyperlattice on itself which commute with the symmetry group, is used to show that the packing densities and the whole structure of the projected quasilattice are periodic under scale transformations. We find the optimal compact acceptance domains and packing densities for several icosahedral problems. For the packing of spheres on the primitive lattice, an icosahedron and the truncated triacontahedron give equal densities but different quasilattices. For the packing of icosahedra one finds only the second lattice and a very high density. For the fcc and bcc lattices the maximum density acceptance domain is a triacontahedron and the densities are considerably lower. The results of Henley for including correlations to increase the density are reformulated in terms of a graph problem in perpendicular space. Including only the graphs equivalent to his, we find the same packing density for the two primitive and for the fcc lattice. It is shown that a generalization leads to an interesting and very complex problem in graph theory which we are unable to solve
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
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
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)
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
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.
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.
Local solution for a class of mixed boundary value problems
International Nuclear Information System (INIS)
A local method is developed for solving locally partial differential equations with mixed boundary conditions. The method is based on a heuristic idea, properties of diffusion processes, stopping times and the Ito formula for semimartingales. According to the heuristic idea, the diffusion process used for solving locally a partial differential with mixed boundary conditions is stopped when it reaches a Neumann boundary and then restarted inside the domain of definition of this equation at a point depending on the Neumann conditions. The proposed method is illustrated and its accuracy assessed by two simple numerical examples solving locally mixed boundary value problems in one and two space dimensions
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.
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.
ADOPTING THE PROBLEM BASED LEARNING APPROACH IN A GIS PROJECT MANAGEMENT CLASS
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...
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.
Does the non-identity problem block a class of arguments against cloning?
Green, Richard
2004-01-01
One class of argument against cloning human beings in the contemporary literature focuses on the bad consequences that will befall the clone or "later-twin." In this paper I consider whether this line of argumentation can be blocked by invoking Parfit's non-identity problem. I canvass two general strategies for solving the non-identity problem: a consequentialist strategy and non-consequentialist, rights based strategy. I argue that while each general strategy offers a plausible solution to the non-identity problem as applied to the cases most frequently discussed in the non-identity problem literature, neither provides a reason for putting aside the non-identity problem when applied to cloning. I conclude (roughly) that the non-identity problem does serve to block this class of argument against cloning. PMID:15468498
Problem-Based Inquiry on World Water Problems in Large Undergraduate Classes
Halvorson, Sarah J.; Wescoat, James L., Jr.
2002-01-01
This paper reports on the design and implementation of a project-based course--World Water Problems--that was introduced within the framework of introductory undergraduate geography education. The aims of the course were twofold: (1) to cultivate in students a world geographic perspective on water problems; and (2) to conduct an original research…
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.
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...
Online Mixed Packing and Covering
Bhaskar, Umang
2012-01-01
In many problems, the inputs arrive over time, and must be dealt with irrevocably when they arrive. Such problems are online problems. A common method of solving online problems is to first solve the corresponding linear program, and then round the fractional solution online to obtain an integral solution. We give algorithms for solving linear programs with mixed packing and covering constraints online. We first consider mixed packing and covering linear programs, where packing constraints are given offline and covering constraints are received online. The objective is to minimize the maximum multiplicative factor by which any packing constraint is violated, while satisfying the covering constraints. No prior sublinear competitive algorithms are known for this problem. We give the first such --- a polylogarithmic-competitive algorithm for solving mixed packing and covering linear programs online. We also show a nearly tight lower bound. Our techniques for the upper bound use an exponential penalty function in...
Random sequential packing of cubes
Sikiric, Mathieu Dutour
2011-01-01
In this volume very simplified models are introduced to understand the random sequential packing models mathematically. The 1-dimensional model is sometimes called the Parking Problem, which is known by the pioneering works by Flory (1939), Renyi (1958), Dvoretzky and Robbins (1962). To obtain a 1-dimensional packing density, distribution of the minimum of gaps, etc., the classical analysis has to be studied. The packing density of the general multi-dimensional random sequential packing of cubes (hypercubes) makes a well-known unsolved problem. The experimental analysis is usually applied to t
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.
Class and Home Problems: Humidification, a True "Home" Problem for p. Chemical Engineer
Condoret, Jean-Stephane
2012-01-01
The problem of maintaining hygrothermal comfort in a house is addressed using the chemical engineer's toolbox. A simple dynamic modelling proved to give a good description of the humidification of the house in winter, using a domestic humidifier. Parameters of the model were identified from a simple experiment. Surprising results, especially…
Regular Totally Separable Sphere Packings
Reid, Samuel
2015-01-01
The topic of totally separable sphere packings is surveyed with a focus on regular constructions, uniform tilings, and contact number problems. An enumeration of all regular totally separable sphere packings in $\\mathbb{R}^2$, $\\mathbb{R}^3$, and $\\mathbb{R}^4$ which are based on convex uniform tessellations, honeycombs, and tetracombs, respectively, is presented, as well as a construction of a family of regular totally separable sphere packings in $\\mathbb{R}^d$ that is not based on a convex...
A class of neutral functional differential equations and the abstract Cauchy problem
International Nuclear Information System (INIS)
In this paper we establish the basic equivalence between the generalized solutions of a certain class of Neutral Functional Differential Equations and the trajectories of the associated abstract Cauchy problem. These results have applications in several fields including Mathematical Biology, Ecology and Control Theory. (author)
Hydrostatic Pressure Project: Linked-Class Problem-Based Learning in Engineering
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…
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.
On a class of non-self-adjoint periodic boundary value problems with discrete real spectrum
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.
Global solutions to a class of CEC benchmark constrained optimization problems
Zhou, Xiaojun
2012-01-01
This paper aims to solve a class of CEC benchmark constrained optimization problems that have been widely studied by nature-inspired optimization algorithms. Global optimality condition based on canonical duality theory is derived. Integrating the dual solutions with the KKT conditions, we are able to obtain the approximate solutions or global solutions easily.
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…
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.
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.
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...
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. .
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.
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.
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.
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
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.
Improving classification of mature microRNA by solving class imbalance problem
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.
Improving classification of mature microRNA by solving class imbalance problem.
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
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...
Analysis and formulation of a class of complex dynamic optimization problems
Kameswaran, Shivakumar
The Direct Transcription approach, also known as the direct simultaneous approach, is a widely used solution strategy for the solution of dynamic optimization problems involving differential-algebraic equations (DAEs). Direct transcription refers to the procedure of approximating the infinite dimensional problem by a finite dimensional one, which is then solved using a nonlinear programming (NLP) solver tailored to large-scale problems. Systems governed by partial differential equations (PDEs) can also be handled by spatially discretizing the PDEs to convert them to a system of DAEs. The objective of this thesis is firstly to ensure that direct transcription using Radau collocation is provably correct, and secondly to widen the applicability of the direct simultaneous approach to a larger class of dynamic optimization and optimal control problems (OCPs). This thesis aims at addressing these issues using rigorous theoretical tools and/or characteristic examples, and at the same time use the results for solving large-scale industrial applications to realize the benefits. The first part of this work deals with the analysis of convergence rates for direct transcription of unconstrained and final-time equality constrained optimal control problems. The problems are discretized using collocation at Radau points. Convergence is analyzed from an NLP/matrix-algebra perspective, which enables the prediction of the conditioning of the direct transcription NLP as the mesh size becomes finer. Several convergence results are presented along with tests on numerous example problems. These convergence results lead to an adjoint estimation procedure given the Lagrange multipliers for the large-scale NLP. The work also reveals the role of process control concepts such as controllability on the convergence analysis, and provides a very important link between control and optimization inside the framework of dynamic optimization. As an effort to extend the applicability of the direct
On the efficient solvability of a simple class of nonlinear knapsack problems
Directory of Open Access Journals (Sweden)
SE Visagie
2008-06-01
Full Text Available In this paper the efficient solvability of a class of nonlinear knapsack problems are investigated by means of the problem's necessary and sufficient conditions. It is shown that, from the general theory, it is impossible to determine sufficient conditions for a solution to be globally optimal. Furthermore, it is shown that even for the smallest possible instance of this problem it is, in general, possible to have an arbitrary large number of solutions for which the necessary conditions hold. These results are then generalised to larger instances of the problem. A possible solution approach is applied to sets of randomly generated problems that utilises the necessary conditions together with the branch-and-bound technique in an attempt to limit the search space. This approach solves mixed 0/1 knapsack problems in order to find all possible solutions satisfying the necessary conditions. Due to the large number of solutions satisfying the necessary conditions the proposed solution approach takes substantially longer than existing branch-and-bound algorithms together with linear enveloping when applied to the same set of problems. This result renders the proposed approach not very efficient.
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.
Finite element formulation and solution of a class of contact-impact problems in contimuum mechanics
International Nuclear Information System (INIS)
Contact-impact phenomena are of importance in many areas of science and technlology, e.g. in nuclear reactor technology where the solution of structural problems involving contact-impact effects is crucial to the design of safe reactor systems. In recent years large-scale computational capabilities have been developed for many areas of structural analysis, the primary technique being the finite element method. At the same time, very few developments have occurred which address themselves to complicated structural problems involving contact-impact effects, and those developments which have been made are of limited generality. The reasons for this lack of development are simple: contact-impact phenomena are inherently nonlinear and the resulting problems are difficult. In this paper the results are described of a research program to develop a finite element formulation and solution procedure for contact-impact problems of a particular class which are termed Hertzian problems. Briefly, Hertzian problems are characterized by the conditions that the contact surface is approximately planar and that the contacting structures have undergone 'small' straining in the neighborhood of the contact surface. (Auth.)
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...
Class attendance and cardiology examination performance: a study in problem-based medical curriculum
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...
A Class of Singular Control Problems and the Smooth Fit Principle
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...
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.
Mond Weir Dual and Wolf Dual in a Class of Nonsmooth Programming Problems
Directory of Open Access Journals (Sweden)
TANG Li-ping
2010-01-01
Full Text Available In this paper duality in a class of nonsmooth programming problem with equality and inequality constraints is considered. Weak duality, strong duality, converse duality and strict converse duality are researched in Mond Weir dual under strict invexity of . Weak duality and strong duality are researched in Wolf dual under invexity of and restricted converse duality and strict converse duality are researched under strict invexity. Some corresponding duality theorems are proved without any constraints. Our results generalize and improve some known results.
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.
Error estimates for a certain class of elliptic optimal control problems
Mali, Olli
2014-01-01
In this paper, error estimates are presented for a certain class of optimal control problems with elliptic PDE-constraints. It is assumed that in the cost functional the state is measured in terms of the energy norm generated by the state equation. The functional a posteriori error estimates developed by Repin in late 90's are applied to estimate the cost function value from both sides without requiring the exact solution of the state equation. Moreover, a lower bound for the minimal cost fun...
International Nuclear Information System (INIS)
The pack contains teaching material to supply factual information about nuclear energy for those teaching physics or chemistry or general science for GCE examinations. It is intended for use either in class teaching or in some forms of resource-based learning systems. The material comprises: illustrated booklets and accompanying filmstrips on (1) energy from atoms, (2) ionising radiation and its detection, (3) nuclear reactors, and (4) the uses of radioisotopes; wallcharts on (1) nuclear fuel cycle, (2) radioactivity at work, and (3) nuclear reactors for producing electricity; glossary of atomic terms; and teachers' guide. (U.K.)
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 ARnxn and qRn, the linear complementarity problem LCP(A, q is to determine if there is xRn 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.
International Nuclear Information System (INIS)
We develop two classes of quasi-classical dynamics that are shown to conserve the initial quantum ensemble when used in combination with the Feynman-Kleinert approximation of the density operator. These dynamics are used to improve the Feynman-Kleinert implementation of the classical Wigner approximation for the evaluation of quantum time correlation functions known as Feynman-Kleinert linearized path-integral. As shown, both classes of dynamics are able to recover the exact classical and high temperature limits of the quantum time correlation function, while a subset is able to recover the exact harmonic limit. A comparison of the approximate quantum time correlation functions obtained from both classes of dynamics is made with the exact results for the challenging model problems of the quartic and double-well potentials. It is found that these dynamics provide a great improvement over the classical Wigner approximation, in which purely classical dynamics are used. In a special case, our first method becomes identical to centroid molecular dynamics
The pursuit of perfect packing
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...
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.
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
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.
The pursuit of perfect packing
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.
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.
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.
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.
Ng, Albert H; Snow, Christopher D
2011-05-01
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. PMID:21264879
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
Multi-class Fork-Join queues & The stochastic knapsack problem
Ding, Sihan
2011-01-01
Multi-class Fork-Join queues are extension of single-class Fork-Join queues. In a multi-class Fork-Join queuing system, different types of jobs arrive, and then split into several sub-jobs. Those sub-jobs go to parallel processing queues. Then, the synchronization is required before the departure of a job. We found very few scientific efforts in analyzing the multi-class Fork-Join queues. In this thesis, we analyzed the expected sojourn time and the expected synchronization time. Since it is ...
Ge, Xun; Thomas, Michael K.; Greene, Barbara A.
2006-01-01
This study utilized elements of technology-rich ethnography to create a rich description of a multi-user virtual environment in a high school computer programming class. Of particular interest was the transition that took place in classroom culture from one characterized by a well-defined problem solving approach to one more indicative of open…
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…
"Hoffman v. Monsanto": Courts, Class Actions, and Perceptions of the Problem of GM Drift
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…
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…
Packing, coding, and ground states
Cohn, Henry
2016-01-01
These are the lecture notes from my 2014 PCMI graduate summer school lectures. In these lectures, we'll study simple models of materials from several different perspectives: geometry (packing problems), information theory (error-correcting codes), and physics (ground states of interacting particle systems). These perspectives each shed light on some of the same problems and phenomena, while highlighting different techniques and connections. One noteworthy phenomenon is the exceptional symmetr...
Towards optimal packed string matching
DEFF Research Database (Denmark)
Ben-Kiki, Oren; Bille, Philip; Breslauer, Dany;
2014-01-01
-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-size...... string-matching instruction wssm is available in contemporary commodity processors. The other word-size maximum-suffix instruction wslm is only required during the pattern pre-processing. Benchmarks show that our solution can be efficiently implemented, unlike some prior theoretical packed string...... 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...
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
International Nuclear Information System (INIS)
A simplified implementation of the analytical discrete ordinates (ADO) method in radiative transfer with polarization is presented in this work. The class of problems that can be solved with the simplified ADO approach consists of problems defined in plane-parallel geometry and driven by external illumination in the form of obliquely incident parallel rays. Numerical results of benchmark quality are tabulated for the albedo problem with polarization and Lambert reflection. The new results improve on a tabulation made available in a previous work by the authors that was based on the (less accurate) spherical harmonics method.
Hard sphere packings within cylinders.
Fu, Lin; Steinhardt, William; Zhao, Hao; Socolar, Joshua E S; Charbonneau, Patrick
2016-02-23
Arrangements of identical hard spheres confined to a cylinder with hard walls have been used to model experimental systems, such as fullerenes in nanotubes and colloidal wire assembly. Finding the densest configurations, called close packings, of hard spheres of diameter σ in a cylinder of diameter D is a purely geometric problem that grows increasingly complex as D/σ increases, and little is thus known about the regime for D > 2.873σ. In this work, we extend the identification of close packings up to D = 4.00σ by adapting Torquato-Jiao's adaptive-shrinking-cell formulation and sequential-linear-programming (SLP) technique. We identify 17 new structures, almost all of them chiral. Beyond D ≈ 2.85σ, most of the structures consist of an outer shell and an inner core that compete for being close packed. In some cases, the shell adopts its own maximum density configuration, and the stacking of core spheres within it is quasiperiodic. In other cases, an interplay between the two components is observed, which may result in simple periodic structures. In yet other cases, the very distinction between the core and shell vanishes, resulting in more exotic packing geometries, including some that are three-dimensional extensions of structures obtained from packing hard disks in a circle. PMID:26843132
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
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。
A Class of Single Machine Scheduling Problems with Variable Processing Time
Institute of Scientific and Technical Information of China (English)
无
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.
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.
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 0
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
Nodal Solutions for a Class of Fourth-Order Two-Point Boundary Value Problems
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.
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.
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)
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.
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.
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.)
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.
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.
Second-order cone programming formulations for a class of problems in structural optimization
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...
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.
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...
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…
Oberhofer, Margret; Colpaert, Jozef
2015-01-01
TLC Pack stands for Teaching Languages to Caregivers and is a course designed to support migrants working or hoping to work in the caregiving sector. The TLC Pack resources range from A2 to B2 level of the Common European Framework of Reference for Languages (CEFR), and will be made available online in the six project languages: Dutch, English,…
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).
On perfect packings in dense graphs
Balogh, József; Treglown, Andrew
2011-01-01
We say that a graph G has a perfect H-packing if there exists a set of vertex-disjoint copies of H which cover all the vertices in G. We consider various problems concerning perfect H-packings: Given positive intergers n, r, D, we characterise the edge density threshold that ensures a perfect K_r-packing in any graph G on n vertices and with minimum degree at least D. We also give two conjectures concerning degree sequence conditions which force a graph to contain a perfect H-packing. Other related embedding problems are also considered. Indeed, we give a degree sequence condition which forces a graph to contain a copy of K_r, thereby strengthening the minimum degree version of Turan's theorem. We also characterise the edge density threshold that ensures a graph G contains k vertex-disjoint cycles.
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...
Positive Solutions for a Class of Coupled System of Singular Three-Point Boundary Value Problems
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.
Design problems and resolvent for class 1E battery of nuclear power plant
International Nuclear Information System (INIS)
The quantity and capacity of DC and 220 V AC uninterrupted systems have been added since the control systems use DCS. It is very difficulty for design on calculation capacity and bear time during short circuit of battery and mechanics calculation of battery bracket. These problems have been solved by tests and calculations. These are good experiments for new project on battery design. (author)
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…
The Problem of Coherence in English for Business and Technology (EBT) Writing Classes.
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…
On second- order symmetric duality for a class of multiobjective fractional programming problem
Directory of Open Access Journals (Sweden)
Deo Brat Ojha
2012-06-01
Full Text Available This article is concerned with a pair of second-order symmetric duals in the context of non-differentiable multiobjective fractional programming problems. We establish the weak and strong duality theorems for the new pair of dual models. Discussion on some special cases shows that results in this paper extend previous work in this area.
Bouchaud, Jean-Philippe; Didier SORNETTE
1994-01-01
The ability to price risks and devise optimal investment strategies in thé présence of an uncertain "random" market is thé cornerstone of modern finance theory. We first consider thé simplest such problem of a so-called "European call option" initially solved by Black and Scholes using Ito stochastic calculus for markets modelled by a log-Brownien stochastic process. A simple and powerful formalism is presented which allows us to generalize thé analysis to a large class of stochastic processe...
Problem-Based Learning in 9th Grade Chemistry Class: `Intermolecular Forces'
Tarhan, Leman; Ayar-Kayali, Hulya; Urek, Raziye Ozturk; Acar, Burcin
2008-05-01
This research study aims to examine the effectiveness of a problem-based learning (PBL) on 9th grade students’ understanding of intermolecular forces (dipole-dipole forces, London dispersion forces and hydrogen bonding). The student’s alternate conceptions about intermolecular bonding and their beliefs about PBL were also measured. Seventy-eight 9th grade students were stratified by cognitive levels and then randomly assigned to experimental (PBL, 40 students) and control (lecture-style teaching, 38 students) groups. Following a preparatory lesson where activation and remediation of existing knowledge occur, a pre-test was given, and no significant difference was found between the two groups of students ( p > .05). After the instruction was completed, a post-test and also a questionnaire related to the quality of the problem, the teacher’s role and group functioning were administered. Results from the post-test of both groups ( p achievement, remedying formation of alternate conceptions and also social skills.
Enhancing Higher Order Thinking Skills In A Marine Biology Class Through Problem-Based Learning
Richard M. Magsino
2014-01-01
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 ...
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.
Yan Sun
2015-01-01
Under some conditions concerning the first eigenvalues corresponding to the relevant linear operator, we obtain sharp optimal criteria for the existence of positive solutions for p-Laplacian problems with integral boundary conditions. The main methods in the paper are constructing an available integral operator and combining fixed point index theory. The interesting point of the results is that the nonlinear term contains all lower-order derivatives explicitly. Finally, we give some examples ...
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.
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.
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.
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 .
Strohfeldt, Katja; Khutoryanskaya, Olga
2015-11-25
Objective. To introduce a new approach to problem-based learning (PBL) used in a medicinal chemistry practical class for pharmacy students. Design. The chemistry practical class was based on independent studies by small groups of undergraduate students (4-5), who designed their own practical work, taking relevant professional standards into account. Students were guided by feedback and acquired a set of skills important for health-care professionals. The model was tailored to the application of PBL in a chemistry practical class setting for a large student cohort (150 students). The achievement of learning outcomes was based on the submission of relevant documentation, including a certificate of analysis, in addition to peer assessment. Some of the learning outcomes also were assessed in the final written examination. Assessment. The practical was assessed at several time points using detailed marking schemes in order to provide the students with feedback. Students were required to engage with the feedback to succeed in the practical. Conclusion. A novel PBL chemistry laboratory course for pharmacy students was successful in that self-reflective learning and engagement with feedback were encouraged, and students enjoyed the challenging learning experience. Essential skills for health-care professionals were also promoted. PMID:26839430
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)
Packing configuration performance for small stem diameters
International Nuclear Information System (INIS)
The extensive use of graphite packing and its excellent track record for large isolating valves in CANDU, Primary Heat Transfer (PHT) systems has resulted in an increased application of graphite packing on the conventional side. Many of these applications are in air operated valves (AOVs) where the packing sets are used on small stem diameters (<1 inch) with frequent short-cycling strokes (± 10% of full stroke). The direct application of the proven packing configurations for large isolated valves to control valve application has generated problems such as stiction, packing wear and, in isolated cases, stem stall. To address this issue, a test program was conducted at AECL, CRL by MED branch. The testing showed that by reconfiguring the packing sets and using PTFE wafers reductions in stem friction of 50% at ambient conditions, a 3 fold at hot conditions are achievable. The test program also demonstrated benefits gained in packing wear with different stem roughness finishes and the potential need to exercise small stems valves that see less than full stroke cycling. The paper describes the tests results and provides field support experience. (author)
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.
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
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.
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.
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 that they...
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.
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.
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...
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...
Xu, Jiuping; Li, Jun
2002-09-01
In this paper a class of stochastic multiple-objective programming problems with one quadratic, several linear objective functions and linear constraints has been introduced. The former model is transformed into a deterministic multiple-objective nonlinear programming model by means of the introduction of random variables' expectation. The reference direction approach is used to deal with linear objectives and results in a linear parametric optimization formula with a single linear objective function. This objective function is combined with the quadratic function using the weighted sums. The quadratic problem is transformed into a linear (parametric) complementary problem, the basic formula for the proposed approach. The sufficient and necessary conditions for (properly, weakly) efficient solutions and some construction characteristics of (weakly) efficient solution sets are obtained. An interactive algorithm is proposed based on reference direction and weighted sums. Varying the parameter vector on the right-hand side of the model, the DM can freely search the efficient frontier with the model. An extended portfolio selection model is formed when liquidity is considered as another objective to be optimized besides expectation and risk. The interactive approach is illustrated with a practical example.
Muu, Lê D.; Oettli, Werner
1988-01-01
A unifled approach to branch-and-bound and cutting plane methods for solving a certain class of nonconvex optimization problems is proposed. Based on this approach an implementable algorithm is obtained for programming problems with a bilinear objective function and jointly convex constraints.
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.
International Nuclear Information System (INIS)
Biological species have produced many simple but efficient rules in their complex and critical survival activities such as hunting and mating. A common feature observed in several biological motion strategies is that the predator only moves along paths in a carefully selected or iteratively refined subspace (or manifold), which might be able to explain why these motion strategies are effective. In this paper, a unified linear algebraic formulation representing such a predator–prey relationship is developed to simplify the construction and refinement process of the subspace (or manifold). Specifically, the following three motion strategies are studied and modified: motion camouflage, constant absolute target direction and local pursuit. The framework constructed based on this varying subspace concept could significantly reduce the computational cost in solving a class of nonlinear constrained optimal trajectory planning problems, particularly for the case with severe constraints. Two non-trivial examples, a ground robot and a hypersonic aircraft trajectory optimization problem, are used to show the capabilities of the algorithms in this new computational framework. (paper)
Liu, Quan; Chen, Lin
2011-01-01
In this paper,we consider the restless bandit problem, which is one of the most well-studied generalizations of the celebrated stochastic multi-armed bandit problem in decision theory. However, it is known be PSPACE-Hard to approximate to any non-trivial factor. Thus the optimality is very difficult to obtain due to its high complexity. A natural method is to obtain the greedy policy considering its stability and simplicity. However, the greedy policy will result in the optimality loss for its intrinsic myopic behavior generally. In this paper, by analyzing one class of so-called standard reward function, we establish the closed-form condition about the discounted factor \\beta such that the optimality of the greedy policy is guaranteed under the discounted expected reward criterion, especially, the condition \\beta = 1 indicating the optimality of the greedy policy under the average accumulative reward criterion. Thus, the standard form of reward function can easily be used to judge the optimality of the greed...
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)
Optimal online bounded space multidimensional packing
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
Teaching Large Evening Classes
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…
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.
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
Damped Arrow-Hurwicz algorithm for sphere packing
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 ...
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.
Effect of packing method on the randomness of disc packings
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.
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 predictab....... Not all customers can and should grow – thus a firm needs to classify its customers in order to implement the right customer strategy.......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...
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
Separable subgroups have bounded packing
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.
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)
Dense Packings of Polyhedra: Platonic and Archimedean Solids
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...
Ishkhanyan, A M
2014-01-01
We derive 15 classes of time-dependent two-state models solvable in terms of the confluent Heun functions. These classes extend over all the known families of 3- and 2-parametric models solvable in terms of the Gauss hypergeometric and the Kummer confluent hypergeometric functions to more general four-parametric classes involving three-parametric detuning modulation functions. The classes suggest a variety of families of field configurations possessing useful properties not covered by the previously known analytic models. In the case of constant detuning the field configurations defined by the derived classes describe excitations of two-state quantum systems by symmetric or asymmetric pulses of controllable width and edge-steepness. The particular classes out of the derived fifteen that provide constant detuning pulses of finite area are identified and the factors controlling the corresponding pulse shapes are discussed in detail. The positions of the pulse edges for the case of step-wise edges are determined...
Reference book for design of valve packings, sealing high temperature water
International Nuclear Information System (INIS)
Mockups of stuffing boxes for valves in the 1/4 to 1 in. (0.6-2.54cm) pipe size range and ASA 900 and up pressure class were tested to determine how temperature, stuffing box dimensions, packing compressive stress and stem surface finish affect water leak rate, packing friction torque and packing volume loss (creep). One brand of wire-reinforced asbestos braid on graphite-and-asbestos core packing was used in all tests. The theory of leakage through porous media was reviewed with emphasis on application to packed stuffing boxes, and a mathematical framework for relating leakage and packing friction to stuffing box dimensions and compressive stress was developed. The tests gave empirical relationships (1) for leak rate vs temperature, packing compressive stress, stem diameter and packing size, (2) for packing friction torque vs the above variables and (3) for packing creep vs temperature and stress. Packing stress affected leakage far more than any other variable, the leak rate being inversely proportional to stress to the 7.3 power at a packing temperature of 350 deg F (175 deg C). Factors which increase packing compression (density) have a strong reducing effect on leakage and a moderate to zero effect on packing friction torque. Surface finish had no visible effect on leakage, torque or creep. Empirical results and theory have been combined to show how stuffing boxes can be designed for a given leakage rate. Suggestions for decreasing leakage from existing high temperature stuffing boxes are included. (author)
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.
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…
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.
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.
Li, Shuai; Li, Yangming; Wang, Zheng
2013-03-01
This paper presents a class of recurrent neural networks to solve quadratic programming problems. Different from most existing recurrent neural networks for solving quadratic programming problems, the proposed neural network model converges in finite time and the activation function is not required to be a hard-limiting function for finite convergence time. The stability, finite-time convergence property and the optimality of the proposed neural network for solving the original quadratic programming problem are proven in theory. Extensive simulations are performed to evaluate the performance of the neural network with different parameters. In addition, the proposed neural network is applied to solving the k-winner-take-all (k-WTA) problem. Both theoretical analysis and numerical simulations validate the effectiveness of our method for solving the k-WTA problem. PMID:23334164
Dense packing on uniform lattices
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.
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.
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)
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
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)
Narrow sieves for parameterized paths and packings
Björklund, Andreas; Kaski, Petteri; Koivisto, Mikko
2010-01-01
We present randomized algorithms for some well-studied, hard combinatorial problems: the k-path problem, the p-packing of q-sets problem, and the q-dimensional p-matching problem. Our algorithms solve these problems with high probability in time exponential only in the parameter (k, p, q) and using polynomial space; the constant bases of the exponentials are significantly smaller than in previous works. For example, for the k-path problem the improvement is from 2 to 1.66. We also show how to detect if a d-regular graph admits an edge coloring with $d$ colors in time within a polynomial factor of O(2^{(d-1)n/2}). Our techniques build upon and generalize some recently published ideas by I. Koutis (ICALP 2009), R. Williams (IPL 2009), and A. Bj\\"orklund (STACS 2010, FOCS 2010).
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.)
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.
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...
Automating the packing heuristic design process with genetic programming.
Burke, Edmund K; Hyde, Matthew R; Kendall, Graham; Woodward, John
2012-01-01
The literature shows that one-, two-, and three-dimensional bin packing and knapsack packing are difficult problems in operational research. Many techniques, including exact, heuristic, and metaheuristic approaches, have been investigated to solve these problems and it is often not clear which method to use when presented with a new instance. This paper presents an approach which is motivated by the goal of building computer systems which can design heuristic methods. The overall aim is to explore the possibilities for automating the heuristic design process. We present a genetic programming system to automatically generate a good quality heuristic for each instance. It is not necessary to change the methodology depending on the problem type (one-, two-, or three-dimensional knapsack and bin packing problems), and it therefore has a level of generality unmatched by other systems in the literature. We carry out an extensive suite of experiments and compare with the best human designed heuristics in the literature. Note that our heuristic design methodology uses the same parameters for all the experiments. The contribution of this paper is to present a more general packing methodology than those currently available, and to show that, by using this methodology, it is possible for a computer system to design heuristics which are competitive with the human designed heuristics from the literature. This represents the first packing algorithm in the literature able to claim human competitive results in such a wide variety of packing domains. PMID:21609273
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
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,…
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…
Random packing of digitized particles
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
Fast searching in packed strings
DEFF Research Database (Denmark)
Bille, Philip
2011-01-01
the time. However, most strings are stored in a computer in a packed representation with several characters in a single word, giving us the opportunity to read multiple characters simultaneously. In this paper we study the worst-case complexity of string matching on strings given in packed...
Fast Searching in Packed Strings
DEFF Research Database (Denmark)
Bille, Philip
2009-01-01
. However, most strings are stored in a computer in a packed representation with several characters in a single word, giving us the opportunity to read multiple characters simultaneously. In this paper we study the worst-case complexity of string matching on strings given in packed representation. Let m...
UNIFORM PACKING DIMENSION RESULTS FOR MULTIPARAMETER STABLE PROCESSES
Institute of Scientific and Technical Information of China (English)
无
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.
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
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.
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…
Random close packing fractions of lognormal distributions of hard spheres
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...
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.
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....
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...
International Nuclear Information System (INIS)
An abstract class of bifurcation problems is investigated from the essential spectrum of the associated Frechet derivative. This class is a very general framework for the theory of one-dimensional, steady-profile traveling- shock-wave solutions to a wide family of kinetic integro-differential equations from nonequilibrium statistical mechanics. Such integro-differential equations usually admit the Navier--Stokes system of compressible gas dynamics or the MHD systems in plasma dynamics as a singular limit, and exhibit similar viscous shock layer solutions. The mathematical methods associated with systems of partial differential equations must, however, be replaced by the considerably more complex Bifurcation Theory setting. A hierarchy of bifurcation problems is considered, starting with a simple bifurcation problem from a simple eigenvalue. Sections are entitled as follows: introduction and background from mechanics; the mathematical problem: principal results; a generalized operational calculus, and the derivation of the generalized Lyapunov--Schmidt equations; and methods of solution for the Lyapunov--Schmidt and the functional differential equations. 1 figure
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.
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....
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...
Rakkapao, S.; Pengpan, T.; Srikeaw, S.; Prasitpong, S.
2014-01-01
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.
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)
On Packing Densities of Set Partitions
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\\}\\}$.
Liu, Quan; Wang, Kehao; Chen, Lin
2011-01-01
In this paper,we consider the restless bandit problem, which is one of the most well-studied generalizations of the celebrated stochastic multi-armed bandit problem in decision theory. However, it is known be PSPACE-Hard to approximate to any non-trivial factor. Thus the optimality is very difficult to obtain due to its high complexity. A natural method is to obtain the greedy policy considering its stability and simplicity. However, the greedy policy will result in the optimality loss for it...
On the tree packing conjecture
Balogh, József; Palmer, Cory
2012-01-01
The Gy\\'arf\\'as tree packing conjecture states that any set of $n-1$ trees $T_{1},T_{2},..., T_{n-1}$ such that $T_i$ has $n-i+1$ vertices pack into $K_n$. We show that $t=1/10n^{1/4}$ trees $T_1,T_2,..., T_t$ such that $T_i$ has $n-i+1$ vertices pack into $K_{n+1}$ (for $n$ large enough). We also prove that any set of $t=1/10n^{1/4}$ trees $T_1,T_2,..., T_t$ such that no tree is a star and $T_i$ has $n-i+1$ vertices pack into $K_{n}$ (for $n$ large enough). Finally, we prove that $t=1/4n^{1/...
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…
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
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…
Lower bounds for 1-, 2- and 3-dimensional on-line bin packing algorithms
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
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.
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。
Zhang, Can
2011-01-01
This paper studies a time optimal control problem with control constraints of the rectangular type for the linear multi-input time-varying ordinary di?erential equations. The aims of this study are to establish certain necessary and sufficient conditions for the optimal time and time optimal control, and to build up an al- gorithm for the optimal time and time optimal control.
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.
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
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
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...
Sleeping distance in wild wolf packs
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.
Planet Packing in Circumbinary Systems
Kratter, Kaitlin M
2013-01-01
The recent discovery of planets orbiting main sequence binaries will provide crucial constraints for theories of binary and planet formation. The formation pathway for these planets is complicated by uncertainties in the formation mechanism of the host stars. In this paper, we compare the dynamical states of single and binary star planetary systems. Specifically, we pose two questions: (1) What does it mean for a circumbinary system to be dynamically packed? (2) How many systems are required to differentiate between a population of packed or sparse planets? We determine when circumbinary systems become dynamically unstable as a function of the separation between the host-stars and the inner planet, and the first and second planets. We show that these represent unique stability constraints compared to single-star systems. We find that although the existing Kepler data is insufficient to distinguish between a population of packed or sparse circumbinary systems, a more thorough study of circumbinary TTVs combine...
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
Energy Technology Data Exchange (ETDEWEB)
Safin, V.A.
1982-01-01
The packing element of a packer is proposed which consists of an elastic core and outer layer made of plastic sealing material. It is distinguished by the fact that in order to facilitate removal of the packing element from the site of installation, the outer layer has a sublayer made of polymer material which is chemically inactive in relationship to the material of the core, for example polytetrafluoroethylene. The element is also distinguished by the fact that the outer layer together with the sublayer is attached to the core through a nonhardening and nondrying glue composition, for example, based on rubber, rosin, lanolin, vaseline oil and zinc oxide.
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.
A Geometric-Structure Theory for Maximally Random Jammed Packings
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.
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.
Nearly-Linear Time Packing and Covering LP Solvers
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...
Valve packing manual. A maintenance application guide
International Nuclear Information System (INIS)
Since 1970, AECL Chalk River Mechanical Equipment Development (MED) branch has invested over 175 person years in testing related to improving valve packing performance. Successful developments, including, 'live-loading', reduced packing heights, and performance-based packing qualification testing have been implemented. Since 1986, MED and the Integrated Valve Actuator Program Task Force - Valve Packing Steering Committee (IVAP-VPSC) have been involved in the development of combination die-formed graphite packing for use in CANDU plants. Many reports, articles, and specifications have been issued. Due to the large amount of test data and reports, a more user-friendly document has been prepared for everyday use. The Valve Packing Manual is based on many years of MED research and testing, as well as operating experience from CANDU nuclear generating stations (NGS). Since 1986, packing research and testing has been funded by the CANDU Owners Group (COG), the Electric Power Research Institute (EPRI), and participating valve packing manufacturers. The Valve Packing Manual (VPM) provides topical summaries of all work related to valve packing done since 1985. It includes advances in configuration design, stem packing friction, materials specifications, and installation procedures. This paper provides an overview on the application of the VPM with a focus on qualification testing, packing configuration, and stem packing friction. (author)
Directory of Open Access Journals (Sweden)
GÃƒÂ³Ã…ÂºdÃ…Âº A.
2000-03-01
Full Text Available This paper is a continuation of the work on the new approach to the packing problems of randomly embedded granular material proposed by GÃƒÂ³Ã…ÂºdÃ…Âº and Pietrow. In previous paper a quantum mechanical approach (QMA to packing was introduced and 2and 3-dimensional packing experiments for circles (spheres were generated on this basis. Packing fractions were calculated to test the ability to build 2 and 3-dimensional beds with correct properties. In this paper we continue testing the QMA model.
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 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...
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.
Caciotta, Giulio
2011-01-01
The main goal of this work consists in showing that the analytic solutions for a class of characteristic problems for the Einstein vacuum equations have an existence region larger than the one provided by the Cauchy-Kowalevski theorem due to the intrinsic hyperbolicity of the Einstein equations. To prove this result we first describe a geometric way of writing the vacuum Einstein equations for the characteristic problems we are considering, in a gauge characterized by the introduction of a double null cone foliation of the spacetime. Then we prove that the existence region for the analytic solutions can be extended to a larger region which depends only on the validity of the apriori estimates for the Weyl equations, associated to the "Bel-Robinson norms". In particular if the initial data are sufficiently small we show that the analytic solution is global. Before showing how to extend the existence region we describe the same result in the case of the Burger equation, which, even if much simpler, nevertheless...
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.
A genetic programming hyper-heuristic approach to automated packing
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...
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。
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
Packing, tiling, orthogonality and completeness
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...
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 ...
Maintaining Virtual Areas on FPGAs using Strip Packing with Delays
Angermeier, Josef; Kamphans, Tom; Schweer, Nils; Teich, Juergen
2010-01-01
Every year, the computing resources available on dynamically partially reconfigurable devices increase enormously. In the near future, we expect many applications to run on a single reconfigurable device. In this paper, we present a concept for multitasking on dynamically partially reconfigurable systems called virtual area management. We explain its advantages, show its challenges, and discuss possible solutions. Furthermore, we investigate one problem in more detail: Packing modules with time-varying resource requests. This problem from the reconfigurable computing field results in a completely new optimization problem not tackled before. ILP-based and heuristic approaches are compared in an experimental study and the drawbacks and benefits discussed.
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.
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)
Wolf Pack Algorithm for Unconstrained Global Optimization
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...
Call packing bounds for overflow queues
van Dijk; Sluis, van der, B.
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 product form expression is available. It is proven that call packing leads to a guaranteed upper bound for the loss probability. In addition, an analytic error bound for the accuracy is derived which ...
Three techniques for obtaining algebraic circle packings
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 ...
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…
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.
Learning from drivers and conflicts around bedded pack barns
Galama, P.J.; Dooren, van, H.J.C.; Eilers, C.H.A.M.
2012-01-01
Due to problems with the freestall a network of dairy farmers in the Netherlands started looking for alternative housing systems for dairy cattle. Therefore researchers and dairy farmers shared ideas and looked abroad in America and Israel for housing systems without cubicles. This gave inspiration for deep bedded pack systems like in these countries. The drivers (motivations) for these housing systems were animal welfare and manure quality. However, they had to be made suitable for the Dutch...
Matroid intersection, base packing and base covering for infinite matroids
Bowler, Nathan; Carmesin, Johannes
2012-01-01
As part of the recent developments in infinite matroid theory, there have been a number of conjectures about how standard theorems of finite matroid theory might extend to the infinite setting. These include base packing, base covering, and matroid intersection and union. We show that several of these conjectures are equivalent, so that each gives a perspective on the same central problem of infinite matroid theory. For finite matroids, these equivalences give new and simpler proofs for the f...
Pebble bed packing in prismatic containers
International Nuclear Information System (INIS)
Highlights: • The essential part of ceramic breeder blankets is pebble beds. • The packing factor for blanket relevant cavities must be known. • Tomography experiments revealed details of packing arrangements. • Packing experiments confirm that reference packing factors will be achieved. -- Abstract: New analyses of previous tomography investigations show in detail void fraction fluctuations close to walls generated by regular pebble arrangements. Local packing factors within the pebble bed were determined for characteristic zones. These results are very helpful for the interpretation of the packing experiments performed with spherical pebbles in different kinds of Plexiglas containers dominated by flat walls. The packing factors for single-size pebbles in the containers with a piston on top are fairly independent of bed height unless the height to diameter ratio becomes less than 10. For the closed rectangular containers, the development of structured packings is rendered more difficult. However, for blanket relevant bed heights, both for orthosilicate and beryllium pebbles, the packing factors obtained which agree well with previously obtained reference values
Imaging of body packing: errors and medico-legal issues.
Reginelli, Alfonso; Russo, Anna; Urraro, Fabrizio; Maresca, Duilia; Martiniello, Ciro; D'Andrea, Alfredo; Brunese, Luca; Pinto, Antonio
2015-10-01
Body packing is the ingestion or insertion in the human body of packed illicit substances. Over the last 20 years, drug smuggling has increased global and new means of transport of narcotics have emerged. Among these, the most frequent one is the gastrointestinal tract: from mouth to anus, vagina, and ears. Cocaine is one of the most traded drugs, followed by heroin. Condoms, latex gloves, and balloons are typically used as drug packets for retention in the body. There are different radiologic modalities to detect illicit drugs in body packing: Plain radiography, computed tomography (CT), ultrasound, and magnetic resonance. Current protocols recommend the use of radiography to confirm packet retention and, in case of doubt, the use of abdominal CT scan with reduced mAs. In case of packet rupture, catastrophic effects can occur. Management of patients carrying packets of drugs is a recurrent medico-legal problem. To improve diagnostic accuracy and prevent hazardous complications, radiologists and emergency physicians should be familiar with radiologic features of body packing. The radiologist plays both a social and a medico-legal role in their assessment, and it should not be limited only to the identification of the packages but must also provide accurate information about their number and their exact location. In this review, we focus on diagnostic errors and medico-legal issues related to the radiological assessment of body packers. PMID:26063072
ÇETİNKAYA, Tufan
2001-01-01
One of the most disturbing problems to the patient after septal surgery is the presence of nasal packing. Postoperative nasal packing use has some advantages and disadvantages. This study was performed to determine whether there's a relation between the duration of postoperative nasal packing and patient complaints. A total of 66 patients undergoing septoplasty or septorhinoplasty were included into the study. The patients were divided into two groups according to the duration of nasal packin...
Minimally packed phases in holography
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.
Minimally packed phases in holography
Donos, Aristomenis; Gauntlett, Jerome P.
2016-03-01
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 at finite chemical potential and in a constant magnetic field, which 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, for a specific value of the magnetic field, that the free energy is minimised by the triangular lattice, associated with minimal packing of circles in the plane. We show that the average stress tensor for the thermodynamically preferred phase is that of a perfect fluid and that this result applies more generally to spontaneously generated periodic phases. The triangular structure persists at low temperatures indicating the existence of novel crystalline ground states.
Chain packing in polycarbonate glasses
Stueber, Dirk; Yu, Tsyr-Yan; Hess, Berk; Kremer, Kurt; O'Connor, Robert D.; Schaefer, Jacob
2010-03-01
Chain packing in homogeneous blends of carbonate C13-labeled bisphenol A polycarbonate with either (i) CF3-labeled bisphenol A polycarbonate or (ii) ring-F-labeled bisphenol A polycarbonate has been characterized using C13{F19} rotational-echo double-resonance (REDOR) nuclear magnetic resonance. In both blends, the C13 observed spin was at high concentration, and the F19 dephasing or probe spin was at low concentration. In this situation, an analysis in terms of a distribution of isolated heteronuclear pairs of spins is valid. Nearest-neighbor separation of C13 and F19 labels was determined by accurately mapping the initial dipolar evolution using a shifted-pulse version of REDOR. Based on the results of this experiment, the average distance from a ring-fluorine to the nearest C13O is more than 1.2 Å greater than the corresponding CF3C13O distance. Next-nearest and more-distant-neighbor separations of labels were measured in a 416-rotor-cycle constant-time version of REDOR for both blends. Statistically significant local order was established for the nearest-neighbor labels in the methyl-labeled blend. These interchain packing results are in qualitative agreement with predictions based on coarse-grained simulations of a specially adapted model for bisphenol A polycarbonate. The model itself has been previously used to determine static and dynamic properties of polycarbonate with results in good agreement with those from rheological and neutron scattering experiments.
Directory of Open Access Journals (Sweden)
Sherry Fukuzawa
2016-06-01
Full Text Available Large first year undergraduate courses have unique challenges in the promotion of student engagement and self-directed learning due to resource constraints that prohibit small group discussions with instructors. The Monthly Virtual Mystery was developed to increase student engagement in a large (N = 725 first year undergraduate class in anthropology at the University of Toronto Mississauga. The teaching challenge was to develop a participation component (worth 6% of the final grade that would increase student engagement without incurring any additional resource costs. The goal of the virtual mystery was to incorporate the principles of problem-based learning to engage students in self-directed learning through an online medium. Groups of approximately 50 students collaborated on a series of “virtual” case studies in a discussion board. Students submitted comments or questions each week to identify the information they needed to solve the mystery. A facilitator oversaw the discussion board to guide students in collaboration and resource acquisition. The final grades of students who participated in the virtual mystery (N=297 were compared to students who participated in a passive online learning exercise that involved watching weekly online videos and answering questions in a course reader (N = 347. Student self-selection determined group participation. Participation completion for both the virtual mystery and the course reader were high (78.8% and 91.6% respectively. There were no significant differences in the distribution of final grades between the participation options. The high completion rate of the virtual mystery demonstrated that an active learning project can be implemented using problem-based learning principles through an online discussion board; however, the large online group collaborations were problematic. Students were frustrated with repetition and inequitable participation in such large groups; however, students evaluated
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.
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.
Design of a lithium-ion battery pack for PHEV using a hybrid optimization method
International Nuclear Information System (INIS)
Highlights: • We propose an optimization method for hybrid vehicle battery pack design. • A hybrid gradient-free and gradient-based optimization method is used. • Balance between active material and electrolyte determines battery optimality. • Optimized battery pack satisfies energy and power requirements exactly. • Optimized batteries show 14–18% improvement in properties over initial designs. - Abstract: This paper outlines a method for optimizing the design of a lithium-ion battery pack for hybrid vehicle applications using a hybrid numerical optimization method that combines multiple individual optimizers. A gradient-free optimizer (ALPSO) is coupled with a gradient-based optimizer (SNOPT) to solve a mixed-integer nonlinear battery pack design problem. This method enables maximizing the properties of a battery pack subjected to multiple safety and performance constraints. The optimization framework is applied to minimize the mass, volume and material costs. The optimized pack design satisfies the energy and power constraints exactly and shows 13.9–18% improvement in battery pack properties over initial designs. The optimal pack designs also performed better in driving cycle tests, resulting in 23.1–32.8% increase in distance covered per unit of battery performance metric, where the metric is either mass, volume or material cost
Confined disordered strictly jammed binary sphere packings
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
Particle-size distribution and packing fraction of geometric random packings
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
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.
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)
Call packing bound for overflow loss systems
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
Call packing bounds for overflow queues
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
Pack Density Limitations of Hybrid Parachutes
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.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cold pack. 890.5700 Section 890.5700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5700 Cold pack. (a) Identification....
On maximum cycle packings in polyhedral graphs
Directory of Open Access Journals (Sweden)
Peter Recht
2014-04-01
Full Text Available This paper addresses upper and lower bounds for the cardinality of a maximum vertex-/edge-disjoint cycle packing in a polyhedral graph G. Bounds on the cardinality of such packings are provided, that depend on the size, the order or the number of faces of G, respectively. Polyhedral graphs are constructed, that attain these bounds.
On maximum cycle packings in polyhedral graphs
Peter Recht; Stefan Stehling
2014-01-01
This paper addresses upper and lower bounds for the cardinality of a maximum vertex-/edge-disjoint cycle packing in a polyhedral graph G. Bounds on the cardinality of such packings are provided, that depend on the size, the order or the number of faces of G, respectively. Polyhedral graphs are constructed, that attain these bounds.
Protein Packing Quality Using Delaunay Complexes
DEFF Research Database (Denmark)
Fonseca, Rasmus; Winter, Pawel; Karplus, Kevin
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...
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.
Difference packing arrays and systematic authentication codes
Institute of Scientific and Technical Information of China (English)
无
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.
A two-stage packing procedure for a Portuguese trading company
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...
Prevalence of Salmonella spp. in Packed and Unpacked Red Meat and Chicken in South of Tehran
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 ...
Hawking Colloquium Packed CERN Auditoriums
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 ...
Packing defects into ordered structures
DEFF Research Database (Denmark)
Bechstein, R.; Kristoffersen, Henrik Høgh; Vilhelmsen, L.B.; Rieboldt, F.; Stausholm-Møller, Jess; Wendt, S.; Hammer, B.; Besenbacher, F.
2012-01-01
We have studied vicinal TiO2(110) surfaces by high-resolution scanning tunneling microscopy and density functional theory calculations. On TiO2 surfaces characterized by a high density of ⟨11̅ 1⟩ steps, scanning tunneling microscopy reveals a high density of oxygen-deficient strandlike adstructur...... surfaces because building material is available at step sites. The strands on TiO2(110) represent point defects that are densely packed into ordered adstructures.......We have studied vicinal TiO2(110) surfaces by high-resolution scanning tunneling microscopy and density functional theory calculations. On TiO2 surfaces characterized by a high density of ⟨11̅ 1⟩ steps, scanning tunneling microscopy reveals a high density of oxygen-deficient strandlike adstructures....... With the help of density functional theory calculations we develop a complete structural model for the entire strand and demonstrate these adstructures to be more stable than an equivalent amount of bulk defects such as Ti interstitials. We argue that strands can form particularly easy on stepped...
Models and algorithms for solving packing problems in logistics
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...
The fine triangle intersections for maximum kite packings
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...
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.
About Casting 2D-Bin Packing into Network Flow Theory
Quilliot, Alain; Toussaint, Hélène
2010-01-01
In this paper, we aim at making appear the way Flow and Multicommodity Flow Theory may be used in order to deal with combinatorial geometry problems like the 2D-Bin Packing problem. In order to do it, we introduce a notion of no circuit double flow, we state a Reformulation Theorem which ties some multicommodity flow model with a given bin-packing problem, and we provide an algorithm whose purpose is to study the way one may deal with the no circuit constraint which is at the core of our mult...
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)
[Review: pathophysiology and methodology of nasal packing].
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
Improved Taxation Rate for Bin Packing Games
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.
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.
An amino acid code to define a protein's tertiary packing surface.
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. PMID:26575337
Packing circles and spheres on surfaces
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.
Packing circles and spheres on surfaces
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.
Think Safety When Picking, Packing School Backpacks
... 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 ...
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
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.
Sherry Fukuzawa; Cleo Boyd
2016-01-01
Large first year undergraduate courses have unique challenges in the promotion of student engagement and self-directed learning due to resource constraints that prohibit small group discussions with instructors. The Monthly Virtual Mystery was developed to increase student engagement in a large (N = 725) first year undergraduate class in anthropology at the University of Toronto Mississauga. The teaching challenge was to develop a participation component (worth 6% of the final grade) that wou...
iTreePack: Protein Complex Side-Chain Packing by Dual Decomposition
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...
Multi objective optimization of line pack management of gas pipeline system
International Nuclear Information System (INIS)
This paper addresses the Line Pack Management of the ''GZ1 Hassi R'mell-Arzew'' gas pipeline. For a gas pipeline system, the decision-making on the gas line pack management scenarios usually involves a delicate balance between minimization of the fuel consumption in the compression stations and maximizing gas line pack. In order to select an acceptable Line Pack Management of Gas Pipeline scenario from these two angles for ''GZ1 Hassi R'mell- Arzew'' gas pipeline, the idea of multi-objective decision-making has been introduced. The first step in developing this approach is the derivation of a numerical method to analyze the flow through the pipeline under transient isothermal conditions. In this paper, the solver NSGA-II of the modeFRONTIER, coupled with a matlab program was used for solving the multi-objective problem
Guo, Lin
In recent years, Lithium chemistry based batteries have gained popularity with all automotive manufacturers. Thousands of battery cells are put into a battery pack to satisfy the need of power consumption of vehicles using electric traction. Managing the battery pack for hybrid and electric vehicles is a challenging problem. Despite the advantage of power density and charge retaining capabilities, Lithium ion batteries do not handle over-charge and over-discharge very well compared to other battery chemistries. Therefore, creating an accurate model to predict the battery pack behavior is essential in research and development for battery management systems. This work presents a general technique to extend accepted modeling methodologies for single cells to models for large packs. The theoretical framework is accompanied by parameter identification process based on the circuit model, and experimental verification procedures supporting the validity of this approach.
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....
International Nuclear Information System (INIS)
A generalization of Dirac’s canonical quantization scheme for a system with second-class constraints is proposed, in which the fundamental commutation relations are constituted by all commutators between positions, momenta and Hamiltonian, so they are simultaneously quantized in a self-consistent manner, rather than by those between merely positions and momenta which leads to ambiguous forms of the Hamiltonian and the momenta. The application of the generalized scheme to the quantum motion on a torus leads to a remarkable result: the quantum theory is inconsistent if built up in an intrinsic geometric manner, whereas it becomes consistent within an extrinsic examination of the torus as a submanifold in three dimensional flat space with the use of the Cartesian coordinate system. The geometric momentum and potential are then reasonably reproduced. -- Highlights: •A generalization of Dirac’s canonical quantization is proposed for a system with second-class constraints. •Quantum motion on torus surface is explicitly treated to show how Schrödinger formalism is complementary to the Dirac one. •The embedding effect in quantum mechanics is originated from the quantization
Using distributed genetic algorithms in three-dimensional bin packing for rapid prototyping machines
Lewis, James E.; Ragade, Rammohan K.; Kumar, Anup; Biles, William E.; Ikonen, Ilkka T.
1998-10-01
Genetic algorithms (GAs) are excellent approaches to solving complex problems in optimization with difficult constraints, and in high state space dimensionality problems. The classic bin-packing optimization problem has been shown to be a NP- complete problem. There are GA applications to variations of the bin-packing problem for stock cutting, vehicle loading, air container loading, scheduling, and the knapsack problem. Mostly, these are based on a 1D or 2D considerations. Ikonen et. al. have developed a GA for rapid prototyping called GARP, which utilizes a 3D chromosome structure for the bin- packing of the Sinterstation 2000's build cylinder. GARP allows the Sinterstation to be used more productively. The GARP application was developed for a single CPU machine. Anticipating greater use of time compression technologies, this paper examines the framework necessary to reduce GARP's execution time. This framework is necessary to speed-up the bin-packing evaluation, by the use of distributed or parallel GAs. In this paper, a framework for distribution techniques to improve the efficiency of GARP, and to improve the quality of GARPis solutions is proposed.
Quasistatic packings of droplets in flat microfluidic channels
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.
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.
Coalescence preference in dense packing of bubbles
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).
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…
Packing of ganglioside-phospholipid monolayers
DEFF Research Database (Denmark)
Majewski, J.; Kuhl, T.L.; Kjær, K.; Smith, G.S.
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...... DPPE monolayer and does not distort the hexagonal in-plane unit cell or out-of-plane two-dimensional (2-D) packing compared with a pure DPPE monolayer. The oligosaccharide headgroups were found to extend normally from the monolayer surface, and the incorporation of these glycolipids into DPPE...... 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...
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
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.
On the Multiple Packing Densities of Triangles
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 $\\delta_T^k(T)=\\delta_L^k(T)$.
Testing of packings for stuffing boxes
International Nuclear Information System (INIS)
The stuffing box packings function when they are sealed tight and do not obstruct the movement of the spindle. Characteristic values are necessary to characterise the materials properties of stuffing box packings. Essentially, the definitions of the characteristic values are known and can be calculated in experimental setups. It is absolutely necessary to standardise the characteristic values as well as the testing procedures in order to be able to provide comparable and reproduceable characteristic values. Depending upon the importance of the fittings, it is necessary to guarantee sufficiently exact and reliable assembly for defined operating conditions. (orig.)
Imaging of drug smuggling by body packing.
Sica, Giacomo; Guida, Franco; Bocchini, Giorgio; Iaselli, Francesco; Iadevito, Isabella; Scaglione, Mariano
2015-02-01
Body packing, pushing, and stuffing are hazardous practices with complex medicolegal and social implications. A radiologist plays both a social and a medicolegal role in their assessment, and it should not be limited only to the identification of the packages but must also provide accurate information about their number and their exact location so as to prevent any package remains in the body packer. Radiologists must also be able to recognize the complications associated with these risky practices. Imaging assessment of body packing is performed essentially through plain abdominal X-ray and computed tomography scans. Ultrasound and magnetic resonance imaging, although with some advantages, actually have a limited use. PMID:25639176
Correlation between Voronoi volumes in disc packings
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...
International Nuclear Information System (INIS)
Algorithms to search for crystal structures that optimize some extensive property (energy, volume, etc) typically make use of random particle reorganizations in the context of one or more numerical techniques such as simulated annealing, genetic algorithms or biased random walks, applied to the coordinates of every particle in the unit cell, together with the cell angles and lengths. In this paper we describe the restriction of such searches to predefined isopointal sets, breaking the problem into countable sub-problems which exploit crystal symmetries to reduce the dimensionality of the search space. Applying this method to the search for maximally packed mixtures of hard spheres of two sizes, we demonstrate that the densest packed structures can be identified by searches within a couple of isopointal sets. For the A2B system, the densest known packings over the entire tested range 0.2 A/rB A/rB < 5.0.
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.
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.
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。
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.
Mwanga, Gasper G; Haario, Heikki; Capasso, Vicenzo
2015-03-01
The main scope of this paper is to study the optimal control practices of malaria, by discussing the implementation of a catalog of optimal control strategies in presence of parameter uncertainties, which is typical of infectious diseases data. In this study we focus on a deterministic mathematical model for the transmission of malaria, including in particular asymptomatic carriers and two age classes in the human population. A partial qualitative analysis of the relevant ODE system has been carried out, leading to a realistic threshold parameter. For the deterministic model under consideration, four possible control strategies have been analyzed: the use of Long-lasting treated mosquito nets, indoor residual spraying, screening and treatment of symptomatic and asymptomatic individuals. The numerical results show that using optimal control the disease can be brought to a stable disease free equilibrium when all four controls are used. The Incremental Cost-Effectiveness Ratio (ICER) for all possible combinations of the disease-control measures is determined. The numerical simulations of the optimal control in the presence of parameter uncertainty demonstrate the robustness of the optimal control: the main conclusions of the optimal control remain unchanged, even if inevitable variability remains in the control profiles. The results provide a promising framework for the designing of cost-effective strategies for disease controls with multiple interventions, even under considerable uncertainty of model parameters. PMID:25481226
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.
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
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.
Close packing of rods on spherical surfaces
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.
Random close packing in protein cores
Gaines, Jennifer C.; Smith, W. Wendell; Regan, Lynne; O'Hern, Corey S.
2016-03-01
Shortly after the determination of the first protein x-ray crystal structures, researchers analyzed their cores and reported packing fractions ϕ ≈0.75 , a value that is similar to close packing of equal-sized spheres. A limitation of these analyses was the use of extended atom models, rather than the more physically accurate explicit hydrogen model. The validity of the explicit hydrogen model was proved in our previous studies by its ability to predict the side chain dihedral angle distributions observed in proteins. In contrast, the extended atom model is not able to recapitulate the side chain dihedral angle distributions, and gives rise to large atomic clashes at side chain dihedral angle combinations that are highly probable in protein crystal structures. Here, we employ the explicit hydrogen model to calculate the packing fraction of the cores of over 200 high-resolution protein structures. We find that these protein cores have ϕ ≈0.56 , which is similar to results obtained from simulations of random packings of individual amino acids. This result provides a deeper understanding of the physical basis of protein structure that will enable predictions of the effects of amino acid mutations to protein cores and interfaces of known structure.
Porous bead packings for gas chromatography
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.
Radiological and practical aspects of body packing.
Pinto, A; Reginelli, A; Pinto, F; Sica, G; Scaglione, M; Berger, F H; Romano, L; Brunese, L
2014-04-01
Body packing represents the concealment of illegal substances in a person's body with the aim of smuggling. "Body packers" either swallow drug-filled packets or introduce drug-filled packets into their bodies rectally or vaginally with the purpose of concealing them. The three main smuggled drugs are cocaine, heroin and cannabis products. Body packing represents a serious risk of acute narcotic toxicity from drug exposure, intestinal obstruction owing to pellet impaction and bowel perforation with consequent abdominal sepsis. A suspected body packer is generally admitted to hospital to perform imaging investigations and confirm the presence of drugs in his/her body. Radiological imaging methods are essential to diagnose body packing and to detect potential complications. Increasing sophistication of traffickers and improvements in packaging add to the detection difficulty. Radiologists should be aware of the appearance of drug packets in a range of imaging modalities. This article informs physicians about the challenging aspects of body packing, its background and medicolegal issues, what imaging methods can be used and what criteria are necessary to perform a correct diagnosis. PMID:24472727
Simple Cloud Chambers Using Gel Ice Packs
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…
Close packing of rods on spherical surfaces.
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
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.
The Constrained Bottleneck Transportation Problem
Peerayuth Charnsethikul; Saeree Svetasreni
2007-01-01
Two classes of the bottleneck transportation problem with an additional budget constraint are introduced. An exact approach was proposed to solve both problem classes with proofs of correctness and complexity. Moreover, the approach was extended to solve a class of multi-commodity transportation network with a special case of the multi-period constrained bottleneck assignment problem.
The P.E.A.C.E. Pack: A Computerized Online Assessment of School Bullying
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…
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...
Dimensions of a class of high-dimensional homogeneous Moran sets and Moran classes
Institute of Scientific and Technical Information of China (English)
无
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.
DEFF Research Database (Denmark)
Rijkhoff, Jan
2007-01-01
This article provides an overview of recent literature and research on word classes, focusing in particular on typological approaches to word classification. The cross-linguistic classification of word class systems (or parts-of-speech systems) presented in this article is based on statements found...... in grammatical descriptions of some 50 languages, which together constitute a representative sample of the world’s languages (Hengeveld et al. 2004: 529). It appears that there are both quantitative and qualitative differences between word class systems of individual languages. Whereas some languages...... employ 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...
Experimental studies on the coolability of packed beds. Flooding of hot dry packed beds
International Nuclear Information System (INIS)
In case of a severe accident in a nuclear power plant meltdown of the reactor core can occur and form a packed bed in the lower plenum of the reactor pressure vessel (RPV) after solidification due to contact with water. The removal of after-heat and the long-term coolability is of essential interest. The efficient injection of cooling water into the packed bed has to be assured without endangering the structural integrity of the reactor pressure vessel. The experiments performed aimed to study the dry-out and the quenching (flooding) of hot dry packed beds. Two different inflow variants, bottom- and top-flooding including the variation of the starting temperature of the packed bed and the injection rate were studied. In case of bottom flooding the quenching time increases with increasing packed bed temperature and decreasing injection rate. In case of top flooding the flow pattern is more complex, in a first phase the water flows preferentially toward the RPV wall, the flow paths conduct the water downwards. The flow resistance of the packed bed increases with increasing bed temperatures. The quenching temperatures increase significantly above average.
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.
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.
Self-similar space-filling packings in three dimensions
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.
Alternative conductor arrangements for ITER TF coil winding pack
International Nuclear Information System (INIS)
Different arrangements of round and rectangular conductors and shear plates for the ITER TF coil winding pack have been investigated. Detailed stress analysis for each configuration have been performed for different loading conditions : in-plane force and out-of-plane forces. This analysis includes parametric studies taking into account different mechanical properties of the materials used in the winding pack. With rectangular conductor the peak shear stress remains high and the manufacture of the jacket of the conductor with variable wall thickness raises problems also this solution has not been considered any longer. With round conductors the shear stress generated in the insulation by the out-of-plane force is small compared to the shear stress produced by the in-plane force. - Maximum Von Mises stress in the steel 483 MPa. - Maximum compressive stress in the insulation - 164 MPa. - Maximum interlaminar shear stress in the insulation 38 MPa. Simplification of the manufacturing process including : shear plate machining, transfer of the winding after heat treatment and final assembly of the shear plates and layers have been investigated. (orig.)
Power Cycle Testing of Press-Pack IGBT Chips
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...
Packing and Disorder in Substituted Fullerenes
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.
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.
Liquid fluidization of particles in packed beds
Energy Technology Data Exchange (ETDEWEB)
Glasserman, P. (Dept. de Industrias, Universidad de Buenos Aires (Argentina)); Videla, D. (Dept. de Industrias, Universidad de Buenos Aires (Argentina)); Boehm, U. (Dept. de Industrias, Universidad de Buenos Aires (Argentina))
1994-06-01
The expansion behavior of solid particles fluidized by liquid within fixed packings was studied by the conductimetric method. The electrodes conforming the conductivity cell were embedded in the container walls with their center at half the height of the fluidized bed. The axial solids distribution was also measured by this technique by placing ten conductivity cells along the column. The study is limited to intermediate and turbulent flow regimes, due to the density and size of the particles used. Depending on the geometry of the packed bed, the operating range in terms of superficial velocity and the homogeneity of the fluidized bed differ from those obtained for fluidization in an empty column. Taking into account geometric aspects of the systems, a method of estimating the fluidization parameters is derived. (orig.)
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.
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
Body packing: from seizures to laparotomy.
Janczak, Joanna M; Beutner, Ulrich; Hasler, Karin
2015-01-01
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. PMID:25883813
Is incest common in gray wolf packs?
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.
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.
Multi-objective optimal design of lithium-ion battery packs based on evolutionary algorithms
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.
A packed bed dehumidifier/regenerator for solar air conditioning with liquid desiccants
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.
Optimal analysis of best fit bin packing
Czech Academy of Sciences Publication Activity Database
Dósa, G.; Sgall, Jiří
Berlin: Springer, 2014 - (Esparza, J.; Fraigniaud, P.; Husfeldt, T.; Koutsoupias, E.), s. 429-441. (Lecture Notes in Computer Science. 8572). ISBN 978-3-662-43947-0. [41st International Colloquium, ICALP 2014. Copenhagen (DK), 08.07.2014-11.07.2014] R&D Projects: GA ČR GBP202/12/G061 Keywords : approximation * packing Subject RIV: BA - General Mathematics http://link.springer.com/chapter/10.1007%2F978-3-662-43948-7_36
Energy Efficient, Electric-Hydraulic Power Pack
Nyman, Johan; Rankka, Amy
2015-01-01
Along with increased oil prices and rising environmental issues, a demand for alternatives to combustion engine driven hydraulic applications has risen. In the field of mobile hydraulics, the hydraulic applications have traditionally been driven by the combustion engine of the vehicle on which they are mounted. By instead using a battery driven power pack the hydraulic application is able to operate without the engine running, saving fuel costs and reducing sound levels. In this thesis, the c...
Force Dynamics in Weakly Vibrated Granular Packings
Umbanhowar, Paul; Van Hecke, Martin
2004-01-01
The oscillatory force F_b^ac on the bottom of a rigid, vertically vibrated, grain filled column, reveals rich granular dynamics, even when the peak acceleration of the vibrations is signicantly less than the gravitational acceleration at the earth's surface. For loose packings or high frequencies, F_b^ac 's dynamics are dominated by grain motion. For moderate driving conditions in more compact samples, grain motion is virtually absent, but F_b^ac nevertheless exhibits strongly nonlinear and h...
Leaflet of the Rose4Pack project
Silva, A. Sanches; Costa, H. S.; F. Ramos; Castilho, M.C.; Machado, A. V.; Nóbrega, J. M.; Carneiro, O.S.; Albuquerque, T.G.; Cunha, E. (Emília)
2013-01-01
Projeto “Rose4Pack – Embalagem biodegradável ativa com extracto de alecrim (Rosmarinus officinalis L.) para incrementar a vida útil dos alimentos”, financiado por Fundos FEDER através do Programa Operacional Fatores de Competitividade – COMPETE (FCOMP-01-0124-FEDER-028015) e por Fundos nacionais da FCT – Fundação para a Ciência e a Tecnologia (PTDC/AGR-TEC/3366/2012).
36 CFR 34.10 - Saddle and pack animals.
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....
21 CFR 133.124 - Cold-pack cheese food.
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...
27 CFR 24.308 - Bottled or packed wine record.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottled or packed wine record. 24.308 Section 24.308 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS WINE Records and Reports § 24.308 Bottled or packed wine record. A proprietor who bottles, packs,...
36 CFR 2.16 - Horses and pack animals.
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... equipment. (b) The use of horses or pack animals outside of trails, routes or areas designated for their...
36 CFR 1002.16 - Horses and pack animals.
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... horses or pack animals outside of trails, routes or areas designated for their use. (c) The use of...
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...
48 CFR 211.272 - Alternate preservation, packaging, and packing.
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...
The close-packed triple helix as a possible new structural motif for collagen
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...
The Paradox of Paperless Classes.
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)
HETP evaluation of structured packing distillation column
Directory of Open Access Journals (Sweden)
A. E. Orlando Jr.
2009-09-01
Full Text Available Several tests with a hydrocarbon mixture of known composition (C8-C14, obtained from DETEN Chemistry S.A., have been performed in a laboratory distillation column, having 40mm of nominal diameter and 2.2m high, with internals of Sulzer DX gauze stainless steel structured packing. The main purpose of this work was to evaluate HETP of a structured packing laboratory scale distillation column, operating continuously. Six HETP correlations available in the literature were compared in order to find out which is the most appropriate for structured packing columns working with medium distillates. Prior to the experimental tests, simulation studies using commercial software PRO/II® were performed in order to establish the optimum operational conditions for the distillation, especially concerning operating pressure, top and bottom temperatures, feed location and reflux ratio. The results of PRO/II® were very similar to the analysis of the products obtained during continuous operation, therefore permitting the use of the properties calculated by that software on the theoretical models investigated. The theoretical models chosen for HETP evaluation were: Bravo, Rocha and Fair (1985; Rocha, Bravo and Fair (1993, 1996; Brunazzi and Pagliant (1997; Carlo, Olujić and Pagliant (2006; Olujić et al., (2004. Modifications concerning calculation of specific areas were performed on the correlations in order to fit them for gauze packing HETP evaluation. As the laboratory distillation column was operated continuously, different HETP values were found by the models investigated for each section of the column. The low liquid flow rates in the top section of the column are a source of error for HETP evaluation by the models; therefore, more reliable HETP values were found in the bottom section, in which liquid flow rates were much greater. Among the theoretical models, Olujić et al. (2004 has shown good results relative to the experimental tests. In addition, the
The mechanical behaviour of packed particulates
International Nuclear Information System (INIS)
Within the Canadian Nuclear Fuel Waste Management program, the central concept is to package used fuel in containers that would be deposited in an underground vault in a plutonic rock formation. To provide internal mechanical support for the container, the reference design specifies it to be filled with a matrix of compacted particulate material (called 'packed particulate'), such as quartz sand granules. The focus of this report is on the mechanical properties of the packed-particulate material, based on information drawn from the extant literature. We first consider the packing density of particulate matrices to minimize the remnant porosity and maximize mechanical stability under conditions of external pressure. Practical methods, involving vibratory packing, are reviewed and recommendations made to select techniques to achieve optimum packing density. The behaviour of particulates under compressive loading has been of interest to the powder metallurgy industry (i.e., the manufacture of products from pressed/sintered metal and ceramic powders) since the early decades of this century. We review the evidence showing that in short timescales, stress induced compaction occurs by particle shuffling and rearrangement, elastic distortion, plastic yielding and microfracturing. Analytical expressions are available to describe these processes in a semiquantitative fashion. Time-dependent compaction, mainly via creep mechanisms, is more complex. Much of the theoretical and experimental information is confined to higher temperatures (> 500 degrees C), where deformation rates are more rapid. Thus, for the relatively low ambient temperatures of the waste container (∼100 degrees C), we require analytical techniques to extrapolate the collective particulate creep behaviour. This is largely accomplished by employing current theories of creep deformation, particularly in the form of Deformation Mechanism Maps, which allow estimation of creep rates over a wide range of stress
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.
Lattice Dynamics of the Hexagonal Close-Packed Structure
International Nuclear Information System (INIS)
Lattice dynamics of hexagonal close-packed (hcp) structures, using the Born-von Kármán approach and assuming interactions with any number of interacting neighbours, were calculated. The general properties of a dynamical matrix, coming from the symmetry of hcp structure, have been established. Using the operations of a point group of the symmetry group of hcp structure, the families of equivalent, equidistant lattice points and their force matrices have been evaluated. This permitted the calculation of the elements of the Fourier transform of the dynamical matrix. Using the long waves procedure, the general formulas for elastic constants expressed by elements of a dynamical matrix have been obtained. The phonon dispersion relations have also been evaluated, by a factorization of a secular equation of a problem. In the course of the work a nomenclature convenient for further analysis of formulas obtained has been used. (author)
Spherical Cap Packing Asymptotics and Rank-Extreme Detection
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...
Perturbing the hexagonal circle packing: a percolation perspective
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.
Eating less from bigger packs: Preventing the pack size effect with diet primes.
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
International Nuclear Information System (INIS)
Direct computer simulations of electromagnetic scattering by discrete random media have become an active area of research. In this progress review, we summarize and analyze our main results obtained by means of numerically exact computer solutions of the macroscopic Maxwell equations. We consider finite scattering volumes with size parameters in the range , composed of varying numbers of randomly distributed particles with different refractive indices. The main objective of our analysis is to examine whether all backscattering effects predicted by the low-density theory of coherent backscattering (CB) also take place in the case of densely packed media. Based on our extensive numerical data we arrive at the following conclusions: (i) all backscattering effects predicted by the asymptotic theory of CB can also take place in the case of densely packed media; (ii) in the case of very large particle packing density, scattering characteristics of discrete random media can exhibit behavior not predicted by the low-density theories of CB and radiative transfer; (iii) increasing the absorptivity of the constituent particles can either enhance or suppress typical manifestations of CB depending on the particle packing density and the real part of the refractive index. Our numerical data strongly suggest that spectacular backscattering effects identified in laboratory experiments and observed for a class of high-albedo Solar System objects are caused by CB.
Dlugach, Janna M.; Mishchenko, Michael I.; Liu, Li; Mackowski, Daniel W.
2011-01-01
Direct computer simulations of electromagnetic scattering by discrete random media have become an active area of research. In this progress review, we summarize and analyze our main results obtained by means of numerically exact computer solutions of the macroscopic Maxwell equations. We consider finite scattering volumes with size parameters in the range, composed of varying numbers of randomly distributed particles with different refractive indices. The main objective of our analysis is to examine whether all backscattering effects predicted by the low-density theory of coherent backscattering (CB) also take place in the case of densely packed media. Based on our extensive numerical data we arrive at the following conclusions: (i) all backscattering effects predicted by the asymptotic theory of CB can also take place in the case of densely packed media; (ii) in the case of very large particle packing density, scattering characteristics of discrete random media can exhibit behavior not predicted by the low-density theories of CB and radiative transfer; (iii) increasing the absorptivity of the constituent particles can either enhance or suppress typical manifestations of CB depending on the particle packing density and the real part of the refractive index. Our numerical data strongly suggest that spectacular backscattering effects identified in laboratory experiments and observed for a class of high-albedo Solar System objects are caused by CB.
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.
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.
Hudson, Toby S.; Harrowell, Peter
2011-05-01
Algorithms to search for crystal structures that optimize some extensive property (energy, volume, etc) typically make use of random particle reorganizations in the context of one or more numerical techniques such as simulated annealing, genetic algorithms or biased random walks, applied to the coordinates of every particle in the unit cell, together with the cell angles and lengths. In this paper we describe the restriction of such searches to predefined isopointal sets, breaking the problem into countable sub-problems which exploit crystal symmetries to reduce the dimensionality of the search space. Applying this method to the search for maximally packed mixtures of hard spheres of two sizes, we demonstrate that the densest packed structures can be identified by searches within a couple of isopointal sets. For the A2B system, the densest known packings over the entire tested range 0.2 < rA/rB < 2.5, including some improvements on previous optima, can all be identified by searches within a single isopointal set. In the case of the AB composition, searches of two isopointal sets generate the densest packed structures over the radius ratio range 0.2 < rA/rB < 5.0.
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.
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.
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.
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)
Defects in crystalline packings of twisted filament bundles. II. Dislocations and grain boundaries.
Azadi, Amir; Grason, Gregory M
2012-03-01
Twisted and ropelike assemblies of filamentous molecules are common and vital structural elements in cells and tissues of living organisms. We study the intrinsic frustration occurring in these materials between the two-dimensional organization of filaments in cross section and out-of-plane interfilament twist in bundles. Using nonlinear continuum elasticity theory of columnar materials, we study the favorable coupling of twist-induced stresses to the presence of edge dislocations in the lattice packing of bundles, which leads to a restructuring of the ground-state order of these materials at intermediate twist. The stability of dislocations increases as both the degree of twist and lateral bundle size grow. We show that in ground states of large bundles, multiple dislocations pile up into linear arrays, radial grain boundaries, whose number and length grows with bundle twist, giving rise to a rich class of "polycrystalline" packings. PMID:22587105
Optimal packing of a rotating packed bed for H(2)S removal.
Guo, Kai; Wen, Jiawu; Zhao, Ying; Wang, Yu; Zhang, Zhenzhen; Li, Zongxiang; Qian, Zhi
2014-06-17
The existence of H2S in a system could lead to catalyst deactivation, pipeline corrosion, and environmental pollution. A rotating packed bed (RPB), a novel reactor with high mass transfer efficiency and small dimension, is employed in this study to remove H2S. For RPB, the most significant section for mass transfer is the end-effect zone of packing. A mathematical model for liquid flow in the packing is established to quantify the length of the end-effect zone. A simple and effective visual experimental method is then proposed to investigate the end-effect zone in the RPB. A gas-liquid mass transfer experiment is finally employed to confirm the validity of the proposed mathematical model. With the aid of this model, the length of packing of a RPB used for pilot-scale H2S removal is optimized. The optimized RPB removes 99.8% of H2S (15 vol % to 0.03 vol %) from the system. The proposed model can help optimize the design of a RPB reactor. PMID:24798198
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.
Wolves adapt territory size, not pack size to local habitat quality.
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
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.
Transport apparatus for location of shear pack in shear machine
International Nuclear Information System (INIS)
An apparatus for moving a shear pack of a shear machine between operative and inoperative position is described. It comprises a trolley to support the shear pack, the trolley being mounted on a bogie movable on rails between the inoperative position, at which the shear pack is loaded on to the trolley, and the operative position at which the shear pack is located at the shear machine. The trolley is mounted on inclined runners on the bogie and is releasably connected to the bogie by latching means. This permits the displacement of the trolley relative to the bogie to effect vertical displacement of the shear pack when the shear pack is at the shear machine. (author)
DEFF Research Database (Denmark)
Borges, Pedro Manuel F. C.; Vidal, Rene Victor Valqui
2000-01-01
This paper addresses the problem of fixed channel assignment in cellular communication systems with nonuniform traffic distribution. The objective of the channel assignment is to minimise the average blocking probability. Methods for finding a good allocation can be based on first building a number...... of sets of cochannel cells or allocation patterns and then assigning them to channels. This usually implies that only a subset of the feasible region is attainable. The approach suggested in this paper uses the concept of packed pattern, since all patterns in an optimal solution will be of that kind....... With a constructive method, the entire set of packed patterns is built and used in the optimisation process. The complexity (large-scale and nonlinearity) of the resulting problem suggested the use of general search procedures (local search, tabu search, simulated annealing, etc.), which have the...
Statistical theory of correlations in random packings of hard particles
Jin, Yuliang; Puckett, James G.; Makse, Hernan A.
2014-01-01
A random packing of hard particles represents a fundamental model for granular matter. Despite its importance, analytical modeling of random packings remains difficult due to the existence of strong correlations which preclude the development of a simple theory. Here, we take inspiration from liquid theories for the $n$-particle angular correlation function to develop a formalism of random packings of hard particles from the bottom-up. A progressive expansion into a shell of particles converg...
Contact nonlinearities and linear response in jammed particulate packings
Goodrich, Carl P.; Liu, Andrea J.; Nagel, Sidney R.
2014-01-01
Packings of frictionless athermal particles that interact only when they overlap experience a jamming transition as a function of packing density. Such packings provide the foundation for the theory of jamming. This theory rests on the observation that, despite the multitude of disordered configurations, the mechanical response to linear order depends only on the distance to the transition. We investigate the validity and utility of such measurements that invoke the harmonic approximation and...
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.
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.
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.
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.
Extended Kalman Filter with a Fuzzy Method for Accurate Battery Pack State of Charge Estimation
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...
Prospects and needs for radiation disinfestation of packed fruits and vegetables
International Nuclear Information System (INIS)
In countries with adequate precipitation or irrigation water and high average yearly temperatures the growth of particular crops is favoured. The suitable climatic conditions, however, favour the multiplication of many pests in the stores. The problem of pests of packed fruits and vegetables, although cosmopolitan, presents a particular concern to the developing countries. The pests that are likely to be affected by irradiation and are less susceptible to the conventional methods of control are discussed, and recommendations made. (author). 4 refs, 5 tabs
Heated Debates: Hot-Water Immersion or Ice Packs as First Aid for Cnidarian Envenomations?
Christie L. Wilcox; Yanagihara, Angel A.
2016-01-01
Cnidarian envenomations are an important public health problem, responsible for more deaths than shark attacks annually. For this reason, optimization of first-aid care is essential. According to the published literature, cnidarian venoms and toxins are heat labile at temperatures safe for human application, which supports the use of hot-water immersion of the sting area(s). However, ice packs are often recommended and used by emergency personnel. After conducting a systematic review of the e...
APPLICATION OF PACKING THEORY ON GRADING DESIGN FOR POROUS ASPHALT MIXTURES
Hardiman Hardiman
2004-01-01
The design life of porous asphalt is shorter than dense mix as a consequence of permeability loss due to clogging and poor resistance to disintegration. To mitigate problems associated with clogging, double layer porous asphalt has been constructed in the Netherlands. This paper investigated a development of a new grading design for porous asphalt by varying percentage of aggregate with maximum sizes of 20, 14 and 10mm; a theory of packing was used. The most common method used for grading des...
Human Error in Throat Pack Management: Report of Two Cases.
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
Voronoi tessellation of the packing of fine uniform spheres
Yang, R. Y.; Zou, R. P.; Yu, A. B.
2002-04-01
The packing of uniform fine spherical particles ranging from 1 to 1000 μm has been simulated by means of discrete particle simulation. The packing structure is analyzed, facilitated by the well established Voronoi tessellation. The topological and metric properties of Voronoi polyhedra are quantified as a function of particle size and packing density. The results show that as particle size or packing density decreases, (i) the average face number of Voronoi polyhedra decreases, and the distributions of face number and edge number become broader and more asymmetric; (ii) the average perimeter and area of polyhedra increase, and the distributions of polyhedron surface area and volume become more flat and can be described by the log-normal distribution. The topological and metric properties depicted for the packing of fine particles differ either quantitatively or qualitatively from those reported in the literature although they all can be related to packing density. In particular, our results show that the average sphericity coefficient of Voronoi polyhedra varies with packing density, and although Aboav-Weaire's law is generally applicable, Lewis's law is not valid when packing density is low, which are contrary to the previous findings for other packing systems.
Using Social Class in Counseling Psychology Research
Liu, William Ming; Ali, Saba Rasheed; Soleck, Geoff; Hopps, Joshua; Dunston, Kwesi; Pickett, Theodore
2004-01-01
Social class is an important cultural construct, but it is poorly used in research. Problems in using social class may be associated with its poor definition in previous studies; conflating between social class and socioeconomic status; using objective indices such as income, education, and occupation rather than subjective measures; regarding…
APPLICATION OF PACKING THEORY ON GRADING DESIGN FOR POROUS ASPHALT MIXTURES
Directory of Open Access Journals (Sweden)
Hardiman Hardiman
2004-01-01
Full Text Available The design life of porous asphalt is shorter than dense mix as a consequence of permeability loss due to clogging and poor resistance to disintegration. To mitigate problems associated with clogging, double layer porous asphalt has been constructed in the Netherlands. This paper investigated a development of a new grading design for porous asphalt by varying percentage of aggregate with maximum sizes of 20, 14 and 10mm; a theory of packing was used. The most common method used for grading design is based on empirical, which does not relate the packing behaviour of the aggregate mass. The packing theory used in this study was facilitated by a vibratory compactor. It was found that mixtures containing aggregate sizes 14 and 10mm have a good permeability and stability, when vibrated for 65 second with a frequency of 40Hz, while for aggregates containing 20mm, to achieve the requirement for Marshall stability, the gradation needs to be modified. Properties of porous asphalt based on packing theory are better from the empirical grading from Spain (P-12.
Bucking the pack ice to Prudhoe Bay
Energy Technology Data Exchange (ETDEWEB)
Kizzia, T.
1976-05-01
Forty-seven giant barges with a billion dollars worth of freight for the Alaska pipeline had been waiting since July 4, 1975 to proceed on through the ice to make the 300-mile run to Prudhoe Bay. Normally, easterly summer winds blow the pack ice into the Chukchi Sea where wave action breaks it up, leaving a broad highway of open water along Alaska's north coast, but the winds in 1975 failed to materialize. Ten of the barges had gone through during August and then a violent westerly storm swept in. When the storm was over, 22 barge skippers returned to Seward, and in mid-September 15 mammouth barges were ice bound. The Coast Guard was called out and with success the icebreakers and tugs began arriving with the cargo in Prudhoe Bay on September 30. The unloading of the cargo also brought difficulties, but before the cargo became frozen in, much of it was unloaded. (MCW)
Meromorphic Vector Fields and Circle Packings
DEFF Research Database (Denmark)
Dias, Kealey
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 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 as...... singularities) functions. There already exists a well-developed theory for iterative holomorphic dynamical systems, and successful relations found between iteration theory and flows of vector fields have been one of the main motivations for the recent interest in holomorphic vector fields. Restricting to...
Lehman, N.; Clarkson, P.; Mech, L.D.; Meier, T.J.; Wayne, R.K.
1992-01-01
DNA fingerprinting and mitochondrial DNA analyses have not been used in combination to study relatedness in natural populations. We present an approach that involves defining the mean fingerprint similarities among individuals thought to be unrelated because they have different mtDNA genotypes. Two classes of related individuals are identified by their distance in standard errors above this mean value. The number of standard errors is determined by analysis of the association between fingerprint similarity and relatedness in a population with a known genealogy. We apply this approach to gray wolf packs from Minnesota, Alaska, and the Northwest Territories. Our results show that: (1) wolf packs consist primarily of individuals that are closely related genetically, but some packs contain unrelated, non-reproducing individuals; (2) dispersal among packs within the same area is common; and (3) short-range dispersal appears more common for female than male wolves. The first two of these genetically-based observations are consistent with behavioral data on pack structure and dispersal in wolves, while the apparent sex bias in dispersal was not expected.
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.)
Algorithms and Models For Combinatorial Optimization Problems
Fernandes Muritiba, Albert Einstein
2010-01-01
In this thesis we present some combinatorial optimization problems, suggest models and algorithms for their effective solution. For each problem,we give its description, followed by a short literature review, provide methods to solve it and, finally, present computational results and comparisons with previous works to show the effectiveness of the proposed approaches. The considered problems are: the Generalized Traveling Salesman Problem (GTSP), the Bin Packing Problem with Conflicts(BPPC) a...
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.
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.
Agnolin, Ivana; Massaad, Pascal; Jia, Xiaoping; Mills, Pierre
2009-01-01
Numerical simulations are used to investigate the origins of the different wave velocities measured in dense granular samples assembled with different methods. Glass bead packings are prepared in the lab either by pouring and vibrating the dry material in a container, or by mixing with a very small amount of a viscous lubricant. Lubricated samples, although less dense, exhibit significantly higher wave velocities for confining pressures in the 100 kPa range. Numerical predictions for elastic moduli agree much better with experimental results when the computational preparation of the samples mimics the laboratory one, albeit in a simplified manner. A plausible explanation to the laboratory observations is that the coordination number, which influences the material stiffness more than its density, is notably higher in lubricated packings.
Python Classes for Numerical Solution of PDE's
Asif Mushtaq; Trond Kvamsdal; Kare Olaussen
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).
Variational Lie derivative and cohomology classes
Palese, Marcella; Winterroth, Ekkehart
2011-07-01
We relate cohomology defined by a system of local Lagrangian with the cohomology class of the system of local variational Lie derivative, which is in turn a local variational problem; we show that the latter cohomology class is zero, since the variational Lie derivative `trivializes' cohomology classes defined by variational forms. As a consequence, conservation laws associated with symmetries of the second variational derivative of a local variational problem are globally defined.
The Performance of Structured Packings in Trickle-Bed Reactors
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
The performance of structured packings in trickle-bed reactors.
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
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...
76 FR 251 - Country of Origin Labeling of Packed Honey
2011-01-04
... 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 USDA... service for honey if country of origin labeling requirements are not met for packages of honey...
A selection-quotient process for packed word Hopf algebra
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.
Hydrodynamics of multi-phase packed bed micro-reactors
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
21 CFR 890.5730 - Moist heat pack.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Moist heat pack. 890.5730 Section 890.5730 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5730 Moist heat pack....
27 CFR 24.255 - Bottling or packing wine.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottling or packing wine. 24.255 Section 24.255 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS WINE Storage, Treatment and Finishing of Wine Bottling, Packing, and Labeling of Wine § 24.255 Bottling...
On spanning tree packings of highly edge connected graphs
Lehner, Florian
2011-01-01
We prove a refinement of the tree packing theorem by Tutte/Nash-Williams for finite graphs. This result is used to obtain a similar result for end faithful spanning tree packings in certain infinite graphs and consequently to establish a sufficient Hamiltonicity condition for the line graphs of such graphs.
48 CFR 852.214-73 - Alternate packaging and packing.
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...
48 CFR 552.211-75 - Preservation, Packaging and Packing.
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...
The effect of nanoparticle packing on capacitive electrode performance
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
Statistical theory of correlations in random packings of hard particles.
Jin, Yuliang; Puckett, James G; Makse, Hernán A
2014-05-01
A random packing of hard particles represents a fundamental model for granular matter. Despite its importance, analytical modeling of random packings remains difficult due to the existence of strong correlations which preclude the development of a simple theory. Here, we take inspiration from liquid theories for the n-particle angular correlation function to develop a formalism of random packings of hard particles from the bottom up. A progressive expansion into a shell of particles converges in the large layer limit under a Kirkwood-like approximation of higher-order correlations. We apply the formalism to hard disks and predict the density of two-dimensional random close packing (RCP), ϕ(rcp) = 0.85 ± 0.01, and random loose packing (RLP), ϕ(rlp) = 0.67 ± 0.01. Our theory also predicts a phase diagram and angular correlation functions that are in good agreement with experimental and numerical data. PMID:25353787
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.
Packing regularities in biological structures relate to their dynamics.
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
Geometry of Online Packing Linear Programs
Molinaro, Marco
2012-01-01
We consider packing LP's with $m$ rows where all constraint coefficients are normalized to be in the unit interval. The n columns arrive in random order and the goal is to set the corresponding decision variables irrevocably when they arrive so as to obtain a feasible solution maximizing the expected reward. Previous (1 - \\epsilon)-competitive algorithms require the right-hand side of the LP to be Omega((m/\\epsilon^2) log (n/\\epsilon)), a bound that worsens with the number of columns and rows. However, the dependence on the number of columns is not required in the single-row case and known lower bounds for the general case are also independent of n. Our goal is to understand whether the dependence on n is required in the multi-row case, making it fundamentally harder than the single-row version. We refute this by exhibiting an algorithm which is (1 - \\epsilon)-competitive as long as the right-hand sides are Omega((m^2/\\epsilon^2) log (m/\\epsilon)). Our techniques refine previous PAC-learning based approaches ...
Evaluation of ceramic packed-rod regenerator matrices
Lawless, W. N.; Arenz, R. W.
1981-01-01
An extensive evaluation of a modified cryocooler with various regenerator matrices is reported. The matrices examined are 0.015 in. diam. Pb spheres and 0.008, 0.015, and 0.030 in. diam. rods of a 0.2% SnCl2 doped ceramic labelled LS-8A. Specific heat and thermal conductivity data on these rod materials are also reported. The chronic pulverization/dusting problem common to Pb spheres was investigated. During a 1000 hr life test with 0.0008 in. diam. rods there was no degradation of the refrigerator performance, and a subsequent examination of the rods themselves revealed no evidence of breakage or pulverization. The load temperature characteristics for the rod packed regenerators were inferior to that for the Pb spheres, the effect being to shift the Pb spheres load curve up in temperature. This temperature shift was 5.0, 7.4, and 11.6K for the 0.0008, 0.015, and 0.030 in. diam. rods, respectively.
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.
Do gray wolves (Canis lupus) support pack mates during aggressive inter-pack interactions?
Cassidy, Kira A; McIntyre, Richard T
2016-09-01
For group-living mammals, social coordination increases success in everything from hunting and foraging (Crofoot and Wrangham in Mind the Gap, Springer, Berlin, 2010; Bailey et al. in Behav Ecol Sociobiol 67:1-17, 2013) to agonism (Mosser and Packer in Anim Behav 78:359-370, 2009; Wilson et al. in Anim Behav 83:277-291, 2012; Cassidy et al. in Behav Ecol 26:1352-1360, 2015). Cooperation is found in many species and, due to its low costs, likely is a determining factor in the evolution of living in social groups (Smith in Anim Behav 92:291-304, 2014). Beyond cooperation, many mammals perform costly behaviors for the benefit of group mates (e.g., parental care, food sharing, grooming). Altruism is considered the most extreme case of cooperation where the altruist increases the fitness of the recipient while decreasing its own fitness (Bell in Selection: the mechanism of evolution. Oxford University Press, Oxford 2008). Gray wolf life history requires intra-pack familiarity, communication, and cooperation in order to succeed in hunting (MacNulty et al. in Behav Ecol doi: 10.1093/beheco/arr159 2011) and protecting group resources (Stahler et al. in J Anim Ecol 82: 222-234, 2013; Cassidy et al. in Behav Ecol 26:1352-1360, 2015). Here, we report 121 territorial aggressive inter-pack interactions in Yellowstone National Park between 1 April 1995 and 1 April 2011 (>5300 days of observation) and examine each interaction where one wolf interferes when its pack mate is being attacked by a rival group. This behavior was recorded six times (17.6 % of interactions involving an attack) and often occurred between dyads of closely related individuals. We discuss this behavior as it relates to the evolution of cooperation, sociality, and altruism. PMID:27193460
Effect of structured packing density on performance of air dehumidifier
International Nuclear Information System (INIS)
An experimental study has been conducted to investigate the performance of a liquid desiccant air dehumidifier equipped with a structured packing made of wood for three different densities using triethylene glycol (TEG) as the liquid desiccant. The structured packing densities used were 77, 100 and 200 m2/m3. The performance of the dehumidifier was expressed in terms of the moisture removal rate and the dehumidifier effectiveness under different air and desiccant parameters, i.e. the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. In general, the trend in the dehumidifier performance was similar to that reported by other investigators using random packing. The effect of packing density on moisture removal rate and dehumidifier effectiveness is assessed. The differences in the effectiveness of different packing densities are attributed to the wetting condition. Lower effectiveness of the column is shown with the packing density of 200 m2/m3 compared to the other two packing densities when the air flow rate, inlet concentration and desiccant flow rate are increased. However, higher effectiveness is shown when either the inlet temperature of the air or desiccant is increased
Effect of structured packing density on performance of air dehumidifier
Energy Technology Data Exchange (ETDEWEB)
Abdul-Wahab, S.A. E-mail: sabah1@squ.edu.om; Abu-Arabi, M.K.; Zurigat, Y.H
2004-09-01
An experimental study has been conducted to investigate the performance of a liquid desiccant air dehumidifier equipped with a structured packing made of wood for three different densities using triethylene glycol (TEG) as the liquid desiccant. The structured packing densities used were 77, 100 and 200 m{sup 2}/m{sup 3}. The performance of the dehumidifier was expressed in terms of the moisture removal rate and the dehumidifier effectiveness under different air and desiccant parameters, i.e. the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. In general, the trend in the dehumidifier performance was similar to that reported by other investigators using random packing. The effect of packing density on moisture removal rate and dehumidifier effectiveness is assessed. The differences in the effectiveness of different packing densities are attributed to the wetting condition. Lower effectiveness of the column is shown with the packing density of 200 m{sup 2}/m{sup 3} compared to the other two packing densities when the air flow rate, inlet concentration and desiccant flow rate are increased. However, higher effectiveness is shown when either the inlet temperature of the air or desiccant is increased.
Air dehumidification by triethylene glycol desiccant in a packed column
International Nuclear Information System (INIS)
The performance of an air dehumidifier using triethylene glycol (TEG) as desiccant under hot and humid conditions was investigated. The performance of the dehumidifier was evaluated and expressed in terms of the moisture removal rate and the dehumidifier effectiveness. A packed bed column (dehumidifier) was employed, with low packing density (77 m2/m3), to provide direct contact between the air and the TEG. Two different structured packings were used, wood and aluminum. The experiments covered a wide range of parameter space that included the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. The liquid flow rate investigated is much less than that covered in previous studies (2 s). The trend of the dehumidifier performance was similar to that reported in the literature using high density and random packing. The results were compared to the Chung and Luo correlation, which over predicted the effectiveness. The Martin and Goswami correlation failed to predict the effectiveness under the conditions of this study. In the present study, it was found that the moisture removal rate increased with increasing inlet TEG concentration, TEG flow rate and air flow rate. This was seen for both the wood and the aluminum packings. In addition, the moisture removal rate is increased with increasing the inlet air temperature for the aluminum packing only. The effectiveness of the column was increased by increasing the TEG flow rate and inlet TEG temperature for the two packings
Air dehumidification by triethylene glycol desiccant in a packed column
Energy Technology Data Exchange (ETDEWEB)
Zurigat, Y.H.; Abu-Arabi, M.K.; Abdul-Wahab, S.A. E-mail: sabah1@squ.edu.om
2004-01-01
The performance of an air dehumidifier using triethylene glycol (TEG) as desiccant under hot and humid conditions was investigated. The performance of the dehumidifier was evaluated and expressed in terms of the moisture removal rate and the dehumidifier effectiveness. A packed bed column (dehumidifier) was employed, with low packing density (77 m{sup 2}/m{sup 3}), to provide direct contact between the air and the TEG. Two different structured packings were used, wood and aluminum. The experiments covered a wide range of parameter space that included the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. The liquid flow rate investigated is much less than that covered in previous studies (<1 kg/m{sup 2} s). The trend of the dehumidifier performance was similar to that reported in the literature using high density and random packing. The results were compared to the Chung and Luo correlation, which over predicted the effectiveness. The Martin and Goswami correlation failed to predict the effectiveness under the conditions of this study. In the present study, it was found that the moisture removal rate increased with increasing inlet TEG concentration, TEG flow rate and air flow rate. This was seen for both the wood and the aluminum packings. In addition, the moisture removal rate is increased with increasing the inlet air temperature for the aluminum packing only. The effectiveness of the column was increased by increasing the TEG flow rate and inlet TEG temperature for the two packings.
PackBot: a versatile platform for military robotics
Yamauchi, Brian M.
2004-09-01
The iRobot PackBot is a combat-tested, man-portable UGV that has been deployed in Afghanistan and Iraq. The PackBot is also a versatile platform for mobile robotics research and development that supports a wide range of payloads suitable for many different mission types. In this paper, we describe four R&D projects that developed experimental payloads and software using the PackBot platform. CHARS was a rapid development project to develop a chemical/radiation sensor for the PackBot. We developed the CHARS payload in six weeks and deployed it to Iraq to search for chemical and nuclear weapons. Griffon was a research project to develop a flying PackBot that combined the capabilities of a UGV and a UAV. We developed a Griffon prototype equipped with a steerable parafoil and gasoline-powered motor, and we completed successful flight tests including remote-controlled launch, ascent, cruising, descent, and landing. Valkyrie is an ongoing research and development project to develop a PackBot payload that will assist medics in retrieving casualties from the battlefield. Wayfarer is an applied research project to develop autonomous urban navigation capabilities for the PackBot using laser, stereo vision, GPS, and INS sensors.
Differential equations problem solver
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
Enabling Microliquid Chromatography by Microbead Packing of Microchannels
Balvin, Manuel; Zheng, Yun
2014-01-01
The microbead packing is the critical element required in the success of on-chip microfabrication of critical microfluidic components for in-situ analysis and detection of chiral amino acids. In order for microliquid chromatography to occur, there must be a stationary phase medium within the microchannel that interacts with the analytes present within flowing fluid. The stationary phase media are the microbeads packed by the process discussed in this work. The purpose of the microliquid chromatography is to provide a lightweight, low-volume, and low-power element to separate amino acids and their chiral partners efficiently to understand better the origin of life. In order to densely pack microbeads into the microchannels, a liquid slurry of microbeads was created. Microbeads were extracted from a commercially available high-performance liquid chromatography column. The silica beads extracted were 5 microns in diameter, and had surface coating of phenyl-hexyl. These microbeads were mixed with a 200- proof ethanol solution to create a microbead slurry with the right viscosity for packing. A microfilter is placed at the outlet via of the microchannel and the slurry is injected, then withdrawn across a filter using modified syringes. After each injection, the channel is flushed with ethanol to enhance packing. This cycle is repeated numerous times to allow for a tightly packed channel of microbeads. Typical microbead packing occurs in the macroscale into tubes or channels by using highly pressurized systems. Moreover, these channels are typically long and straight without any turns or curves. On the other hand, this method of microbead packing is completed within a microchannel 75 micrometers in diameter. Moreover, the microbead packing is completed into a serpentine type microchannel, such that it maximizes microchannel length within a microchip. Doing so enhances the interactions of the analytes with the microbeads to separate efficiently amino acids and amino acid
Identification of Sec14-like 3 as a novel lipid-packing sensor in the lung.
Hishikawa, Daisuke; Shindou, Hideo; Harayama, Takeshi; Ogasawara, Rie; Suwabe, Akira; Shimizu, Takao
2013-12-01
Pulmonary surfactant, a complex composed primarily of lipids and associated proteins, is synthesized in alveolar type II (ATII) cells and secreted into alveoli to prevent collapse during respiration. Although numerous studies have clarified the fundamental roles of pulmonary surfactant, the molecular mechanisms of transport and secretion of pulmonary surfactant remain totally unknown. Thus, we screened candidate genes by comparing genes with the expressed sequence tag (EST) libraries of embryonic and adult lungs by using the digital differential display method in the National Center for Biotechnology Information (NCBI) database. We identified Sec14-like 3 (Sec14L3) as a new class of lipid-associated proteins highly expressed in ATII cells. We found that Sec14L3 expression is >100-fold increased during the perinatal period in the lung. Furthermore, Sec14L3 bound to small-sized liposomes (30 nm in diameter), but not to large-sized liposomes (100 nm diameter), through its Sec14 domain. Because of the increased curvature, lipid-packing defects are more likely to occur in small-sized liposomes than in large-sized liposomes. Based on these results, we conclude that Sec14L3 is a new class of lipid-packing sensor. Sec14L3 may play important roles in the lung, such as intracellular lipid transport, surfactant maturation, and endo/exocytosis. PMID:24018064
The Use of Inorganic Packing Materials during Methane Biofiltration
Josiane Nikiema; Michèle Heitz
2010-01-01
The objective behind this study is to select a suitable inorganic packing material for methane biofiltration. Three packing materials are to be compared: two rock materials (average particles' sizes: 2 and 5 mm) and one porous clay particles (average particle size of 7 mm). The main parameter used to assess the efficiency of the packing material is the methane elimination capacity. The study reveals that the rock material having an average particle size around 2 mm is to be preferred. This re...
Intelligent charging and control of portable battery packs
Kjellberg, Olof
2008-01-01
This report describes thesis work performed at SAAB Aerotech in Link oping, Sweden. The task was to nd a way to have portable electronics' battery packs supervise their own charg- ing i.e. designing a charger that would t inside the battery pack itself. The work was started by identifying the demands that SAAB Aerotech and their customer have on portable bat- tery packs. A survey was done, forming the basis of a design specication that species what an implementation should aim at fullling. Th...
Multilayer DNA Origami Packed on Hexagonal and Hybrid Lattices
DEFF Research Database (Denmark)
Ke, Yonggang; Voigt, Niels Vinther; Shih, William M.; Gothelf, Kurt Vesterager
2012-01-01
“Scaffolded DNA origami” has been proven to be a powerful and efficient approach to construct two-dimensional or three-dimensional objects with great complexity. Multilayer DNA origami has been demonstrated with helices packing along either honeycomb-lattice geometry or square-lattice geometry....... 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...
Packing parameters effect on injection molding of polypropylene nanostructured surfaces
DEFF Research Database (Denmark)
Calaon, Matteo; Tosello, Guido; Hansen, Hans Nørgaard;
2012-01-01
In today´s industry, applications involving surface patterning of sub-μm to nanometer scale structures have shown a high growth potential. To investigate the injection molding capability of replicating sub-μm surface texture on a large scale area, a 30x80 mm2 tool insert with surface structures...... having a diameter of 500 nm was employed. The tool insert surface was produced using chemical-based-batch techniques such aluminum anodization and nickel electroplating. During the injection molding process, polypropylene (PP) was employed as material and packing phase parameters (packing time, packing...
Contact nonlinearities and linear response in jammed particulate packings.
Goodrich, Carl P; Liu, Andrea J; Nagel, Sidney R
2014-08-01
Packings of frictionless athermal particles that interact only when they overlap experience a jamming transition as a function of packing density. Such packings provide the foundation for the theory of jamming. This theory rests on the observation that, despite the multitude of disordered configurations, the mechanical response to linear order depends only on the distance to the transition. We investigate the validity and utility of such measurements that invoke the harmonic approximation and show that, despite particles coming in and out of contact, there is a well-defined linear regime in the thermodynamic limit. PMID:25215727
Ruin problems and tail asymptotics
DEFF Research Database (Denmark)
Rønn-Nielsen, Anders
The thesis Ruin Problems and Tail Asymptotics provides results on ruin problems for several classes of Markov processes. For a class of diffusion processes with jumps an explicit expression for the joint Laplace transform of the first passage time and the corresponding undershoot is derived. An...
Effect of Packing Cost on The Sales Price and Contribution Margin
Gülşah ATAĞAN; Yükçü, Süleyman
2013-01-01
The basic characteristic of packing is to protect the product from external factors while the product is delivering to consumers. However, recently packing has become an indispensable aspect of marketing. Because, packing is considered as a silent dealer which directly reaches consumers. Packing is one of the most important factor of product sales. Consumers assess a product with its packing and make up a purchasing decision accordingly. In addition to its protective function, packing also p...
Preparation and characterization of hexagonal close-packed Ni nanoparticles
Institute of Scientific and Technical Information of China (English)
2008-01-01
Hexagonal close-packed Ni nanoparticles were synthesized using a heat-treating technique with the precursors prepared by the sol-gel method.The synthesis condition,structure,and morphology of the samples were characterized and analysed by thermogravimetric analysis (TG),differential thermal analysis (DTA),X-ray diffraction (XRD) and transmission electron microscopy (TEM).Results indicate that the hexagonal close packed Ni nanoparticles were synthesized at a heat-treating temperature of 300℃.The cell constants are calculated at a=0.2652 nm and c=0.4334 nm.The average grain size of the hexagonal close-packed Ni particles evaluated by Scherrer equation is about 12 nm.The phase transformation from a hexagonal close-packed Ni to a face-centered cubic Ni structure occurred when the heat-treating temperature was increased.
Radiation sterilization of plastic packing materials and aseptic packaging
International Nuclear Information System (INIS)
In the present day of 'satiation', quality, not quantity, is emphasized for foods, the consumers being oriented toward raw and healthy foodstuff. Aseptic Packaging is excellent means of conservation. While conventionally chemicals have been used for sterilization of packing materials for aseptic packaging, the sterilization by radiation is used in part recently. The following are described : history of aseptic packaging and its features, sterilization by radiation, γ-ray sterilization of large-sized containers, the development of an aseptic packaging system using electron rays, the occurrence of offensive odors from packing materials (comparison of odors from various materials, volatile substances occurring in irradiated polyethylene, influence of film grade upon the formation of carboxylic acid, influence of the irradiation conditions upon the occurrences of volatile substances, volatile substances occurring in the irradiation of bag-in-box packing materials), changes in properties of the packing materials. (Mori, K.)
Estimation of maximum coated particle fuel compact packing fraction
International Nuclear Information System (INIS)
This work develops an analytic fuel fraction packing model for a high temperature gas cooled reactor fuel compact fabricated from overcoated particles of a single size. The model includes the effects of one dimensional compression and finite matrix grain size. One dimensional compression limits the maximum fuel packing fraction to about 48% for the pressed compact in this single sized particle system. This limit is due to two effects. The first is that the process of die loading limits the pre-compression packing configuration to one that is stable under gravity, which is not the most space efficient one. The second effect is due to the one dimensional compression which reduces only the axial dimension of the particle lattice rather than uniformly compressing the lattice. The die wall can also limit the maximum packing fraction by preventing the nearby particles from moving into a more space efficient configuration
Structural Evolution of a Granular Pack under Manual Tapping
Iikawa, Naoki; Bandi, Mahesh M.; Katsuragi, Hiroaki
2015-09-01
We experimentally study a two-dimensional (2D) granular pack of photoelastic disks subject to vertical manual tapping. Using bright- and dark-field images, we employ gradient-based image analysis methods to analyze various structural quantities. These include the packing fraction (ϕ), force per disk (Fd), and force chain segment length (l) as functions of the tapping number (τ). The increase in the packing fraction with the tapping number is found to exponentially approach an asymptotic value. An exponential distribution is observed for the cumulative numbers of both the force per disk Fd:Ncum(Fd) = AFexp ( - Fd/F0), and the force chain segment length l:Ncum(l) = Alexp ( - l/l0). Whereas the coefficient AF varies with τ for Fd, l shows no dependence on τ. The τ dependences of Fd and ϕ allow us to posit a linear relationship between the total force of the granular pack Ftot*(τ ) and ϕ(τ).
Excise Tax Rates On Packs Of Cigarettes PDF Slides
U.S. Department of Health & Human Services — Download the current excise tax rates on packs of cigarettes slides. These slides are available in PDF and PowerPoint formats. The PowerPoint version can be found...
Class Vectors: Embedding representation of Document Classes
Sachan, Devendra Singh; Kumar, Shailesh
2015-01-01
Distributed representations of words and paragraphs as semantic embeddings in high dimensional data are used across a number of Natural Language Understanding tasks such as retrieval, translation, and classification. In this work, we propose "Class Vectors" - a framework for learning a vector per class in the same embedding space as the word and paragraph embeddings. Similarity between these class vectors and word vectors are used as features to classify a document to a class. In experiment o...
Computational Fluid Dynamics Simulation of Multiphase Flow in Structured Packings
Saeed Shojaee; Seyyed Hossein Hosseini; Behzad Saeedi Razavi
2012-01-01
A volume of fluid multiphase flow model was used to investigate the effective area and the created liquid film in the structured packings. The computational results revealed that the gas and liquid flow rates play significant roles in the effective interfacial area of the packing. In particular, the effective area increases as the flow rates of both phases increase. Numerical results were compared with the Brunazzi and SRP models, and a good agreement between them was found. Attention was gi...
Preparation of Zirconia Based Packing Material and Its Evaluation
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A new reversed-phase packing (C18-PBD-ZrO2) was prepared by depositing and cross-linking 1-octadecene (ODE or C18) and polybutadiene (PBD) onto the surface of porous zirconia microspheres (5～10 mm in diameter) which were synthesized by a sol-gel process. These novel column packings possess high mechanical and chemical stability,wider usable pH range and can be used to separate basic compounds with no observable peak tailing.
Shock-Induced Flows through Packed Beds: Transient Regimes
Shtemler, Yuri M; Britan, Alex
2006-01-01
The early stage of the transient regimes in the shock-induced flows within solid-packed beds are investigated in the linear longwave and high-frequency approximation. The transient resistance law is refined as the Duhameltime integral that follows from the general concept of dynamic tortuosity and compressibility of the packed beds. A closed-form solution is expected to describe accurately the early stage of the transient regime flow and is in qualitative agreement with available experimental data.
Van Galen, Jane
2008-01-01
In this article, I argue for a closer read of the daily "class work" of teachers, as posited by Reay, 1998. In developing exploratory class portraits of four teachers who occupy distinctive social positions (two from working-class homes now teaching upper-middle-class children and two from upper-middle-class homes now teaching poor children), I…
Energy Technology Data Exchange (ETDEWEB)
Magalhaes, Joao Vicente Martins de; Leal, Rafael Amorim Ferreira; Martins, Andre Leibsohn; Calderon, Agostinho; Ferreira, Marcus Vinicius Duarte [Petrobras S.A., Rio de Janeiro, RJ (Brazil)], E-mails: ivmm@petrobras.com.br, rafaelleal@petrobras.com.br, aleibsohn@petrobras.com.br, agoscal@petrobras.com.br, mvdferreira@petrobras.com.br; Simoes, Bruno; Barbosa, Diego [Halliburton, Novo Cavaleiros, Macae, RJ (Brazil)], E-mails: bruno.simoes@halliburton.com.br, diego.barbosa@halliburton.com.br
2010-07-01
In the petroleum exploitation and production in deep water, at the fields operated by PETROBRAS, Brazil, one of the problems frequently found is the need of elimination of sand production, having in mind that the most of those fields produce from the non consolidated sandstones. The opened well Gravel Packing is the technique most used for that task. Due to the fact of Gravel Packing operations occurs at thousand of meters below the surface, it is necessary the computational simulation for forecasting how particle deposition (Gravel) in the well occurs. So, it was used the commercial pack of fluid dynamics FLUENT 12, which calculates the fluid velocity field, coupled to another commercial pack, the EDEM, based on discrete elements that treat of particle mechanics. The coupling of the two software has shown adequate the comparison of the computational results with the experimental data shows a good adjustment. Besides, it was possible to simulate problems of well early clogging, showing that the computational simulation is strong and capable of captivating such a phenomena.
Spectral action models of gravity on packed swiss cheese cosmology
Ball, Adam; Marcolli, Matilde
2016-06-01
We present a model of (modified) gravity on spacetimes with fractal structure based on packing of spheres, which are (Euclidean) variants of the packed swiss cheese cosmology models. As the action functional for gravity we consider the spectral action of noncommutative geometry, and we compute its expansion on a space obtained as an Apollonian packing of three-dimensional spheres inside a four-dimensional ball. Using information from the zeta function of the Dirac operator of the spectral triple, we compute the leading terms in the asymptotic expansion of the spectral action. They consist of a zeta regularization of the divergent sum of the leading terms of the spectral actions of the individual spheres in the packing. This accounts for the contribution of points 1 and 3 in the dimension spectrum (as in the case of a 3-sphere). There is an additional term coming from the residue at the additional point in the real dimension spectrum that corresponds to the packing constant, as well as a series of fluctuations coming from log-periodic oscillations, created by the points of the dimension spectrum that are off the real line. These terms detect the fractality of the residue set of the sphere packing. We show that the presence of fractality influences the shape of the slow-roll potential for inflation, obtained from the spectral action. We also discuss the effect of truncating the fractal structure at a certain scale related to the energy scale in the spectral action.
Flow boiling heat transfer in volumetrically heated packed bed
International Nuclear Information System (INIS)
Highlights: • The onset of nucleate boiling in the volumetrically heated packed bed is researched. • A correlation for predicting qONB is developed. • The effects on boiling heat transfer coefficient are investigated. - Abstract: The volumetrically heated packed bed has been widely utilized in modern industry. However, due to the variability and randomness of packed bed channels, flow boiling heat transfer characteristics becomes complex, and there are no published research regarding this topic. To study flow boiling heat transfer characteristics of volumetrically heated packed beds, electromagnetic induction heating method is used to heat oxidized carbon steel balls adopted to stack the packed bed, with water as coolant in the experiment. The experimental results indicate that heat flux at onset of nucleate boiling (ONB) increases as mass flux and inlet subcooling are increased. A new correlation is developed to predict the ONB heat flux qONB in volumetrically heated packed bed, the predictions by which agree well with the experimental data, and the deviation remains less than 15%. Subcooled flow boiling heat transfer coefficient (hsub) increases with increasing mass flux, and equilibrium quality is slightly affected by heat flux. The saturated flow boiling heat transfer coefficient (hsat) increases with mass flux and equilibrium quality when equilibrium quality is lower than about 0.05, while the nucleate boiling is suppressed when the equilibrium quality exceeds a certain value
Context-sensitive intra-class clustering
Yu, Yingwei
2014-02-01
This paper describes a new semi-supervised learning algorithm for intra-class clustering (ICC). ICC partitions each class into sub-classes in order to minimize overlap across clusters from different classes. This is achieved by allowing partitioning of a certain class to be assisted by data points from other classes in a context-dependent fashion. The result is that overlap across sub-classes (both within- and across class) is greatly reduced. ICC is particularly useful when combined with algorithms that assume that each class has a unimodal Gaussian distribution (e.g., Linear Discriminant Analysis (LDA), quadratic classifiers), an assumption that is not always true in many real-world situations. ICC can help partition non-Gaussian, multimodal distributions to overcome such a problem. In this sense, ICC works as a preprocessor. Experiments with our ICC algorithm on synthetic data sets and real-world data sets indicated that it can significantly improve the performance of LDA and quadratic classifiers. We expect our approach to be applicable to a broader class of pattern recognition problems where class-conditional densities are significantly non-Gaussian or multi-modal. © 2013 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Authors have been developing a cryogenic pressure swing adsorption system for hydrogen isotope separation. In the problem of its design and operation, it is necessary to predict the concentration profiles developing in packed beds of adsorbent pellets. The profiling is affected by the longitudinal dispersion of gas flowing in packed beds, in addition to the mass transfer resistance in porous media of adsorbent pellets. In this work, an equation is derived for estimating the packed-bed dispersion coefficient of hydrogen isotopes, by analyzing the breakthrough curves of trace D2 or HD replacing H2 adsorbed in synthetic zeolite particles packed columns at the liquefied nitrogen temperature 77.4 K. Since specialized for hydrogen isotopes, this equation can be considered to estimate the dispersion coefficients more reliable for the cryogenic hydrogen isotope adsorption process, than the existing equations. (authors)
DEFF Research Database (Denmark)
Hem, Caroline Piper; Makovicky, Emil; Balic Zunic, Tonci
2010-01-01
] 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 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 of...
Ehrenberg, Ronald G.; Brewer, Dominic J.; Gamoran, Adam; Willms, J. Douglas
2001-01-01
Reports on the significance of class size to student learning. Includes an overview of class size in various countries, the importance of teacher adaptability, and the Asian paradox of large classes allied to high test scores. (MM)
Generation of Random Particle Packings for Discrete Element Models
Abe, S.; Weatherley, D.; Ayton, T.
2012-04-01
An important step in the setup process of Discrete Element Model (DEM) simulations is the generation of a suitable particle packing. There are quite a number of properties such a granular material specimen should ideally have, such as high coordination number, isotropy, the ability to fill arbitrary bounding volumes and the absence of locked-in stresses. An algorithm which is able to produce specimens fulfilling these requirements is the insertion based sphere packing algorithm originally proposed by Place and Mora, 2001 [2] and extended in this work. The algorithm works in two stages. First a number of "seed" spheres are inserted into the bounding volume. In the second stage the gaps between the "seed" spheres are filled by inserting new spheres in a way so they have D+1 (i.e. 3 in 2D, 4 in 3D) touching contacts with either other spheres or the boundaries of the enclosing volume. Here we present an implementation of the algorithm and a systematic statistical analysis of the generated sphere packings. The analysis of the particle radius distribution shows that they follow a power-law with an exponent ≈ D (i.e. ≈3 for a 3D packing and ≈2 for 2D). Although the algorithm intrinsically guarantees coordination numbers of at least 4 in 3D and 3 in 2D, the coordination numbers realized in the generated packings can be significantly higher, reaching beyond 50 if the range of particle radii is sufficiently large. Even for relatively small ranges of particle sizes (e.g. Rmin = 0.5Rmax) the maximum coordination number may exceed 10. The degree of isotropy of the generated sphere packing is also analysed in both 2D and 3D, by measuring the distribution of orientations of vectors joining the centres of adjacent particles. If the range of particle sizes is small, the packing algorithm yields moderate anisotropy approaching that expected for a face-centred cubic packing of equal-sized particles. However, once Rmin < 0.3Rmax a very high degree of isotropy is demonstrated in
Solid-fluid response of packed-bed regenerators by Crump's numerical inversion of Laplace transforms
International Nuclear Information System (INIS)
The temperature histories in the fluid and the solid phases of a fixed-matrix (packed-bed) thermal storage unit in the regenerative mode of operation, with complete reversals of the flow direction, are traced. The heat conduction and energy storage are considered in the solid, but neglected in the fluid. The problem is solved numerically by the technique of Laplace transforms, with the inversion effected by a fast and robust scheme due to Crump. Sample results are plotted and discussed in physical terms
Study on new-type packing for scram valve of hydraulic control unit
International Nuclear Information System (INIS)
The scram valve, which works at the emergency shutdown of BWR plant, is subjected to change in water pressure depending on plant operational status. The purpose of this study is to reduce the probability of water dripping from the shaft seal part of the valve due to the water pressure drop arising from the shutdown. We have produced a new-type packing, which have higher seal performance under the change in water pressure. We have confirmed that the gasket can be introduced to existing plants without problems from the test results for seal performance. (author)
Using Mobile Phone Technology in EFL Classes
Sad, Süleyman Nihat
2008-01-01
Teachers of English as a foreign language (EFL) who want to develop successful lessons face numerous challenges, including large class sizes and inadequate instructional materials and technological support. Another problem is unmotivated students who refuse to participate in class activities. According to Harmer (2007), uncooperative and…
Directory of Open Access Journals (Sweden)
Ali Karbasfrushan
2014-10-01
Full Text Available Introduction: Nausea and vomiting after ear, nose and throat (ENT surgery is one of the most common and notable problems facing anesthesiologists in this area. This study was conducted to determine the effect of a pharyngeal pack on the severity of nausea, vomiting, and sore throat among patients after ear, pharynx, and throat surgeries. Materials and Methods: This randomized clinical study was performed in 140 patients (61 men and 79 women; age range, 20–40 years who had undergone nasal surgery in 2010. Patients were divided into two groups: the first group were treated using a pharyngeal pack (case group and the second group were managed without a pharyngeal pack (control group. Statistical analysis was performed using the Chi-square test and the Mann-Whitney U test. SPSS software was used for data analysis. Results: The mean severity of nausea and vomiting in the two groups was 2.057, 1.371 and 1.100, respectively, with no significant differences between groups. However, the mean severity of sore throat was 1.714 in the group with the pharyngeal pack and 1.385 in the group without pharyngeal pack (P=0.010. Conclusion: Not only does a pharyngeal pack in ENT surgery not reduce the extent and severity of nausea and vomiting, but it also increases the severity of sore throat in patients when leaving the recovery room and discharging hospital.
Algebraic Structures using Natural Class of Intervals
Kandasamy, W B Vasantha
2011-01-01
This book has eleven chapters. Chapter one describes all types of natural class of intervals and the arithmetic operations on them. Chapter two introduces the semigroup of natural class of intervals using R or Zn and study the properties associated with them. Chapter three studies the notion of rings constructed using the natural class of intervals. Matrix theory using the special class of intervals is analyzed in chapter four of this book. Chapter five deals with polynomials using interval coefficients. New types of rings of natural intervals are introduced and studied in chapter six. The notion of vector space using natural class of intervals is built in chapter seven. In chapter eight fuzzy natural class of intervals are introduced and algebraic structures on them is built and described. Algebraic structures using natural class of neutrosophic intervals are developed in chapter nine.Chapter ten suggests some possible applications. The final chapter proposes over 200 problems of which some are at research l...
关于一类Bush型分形曲面的维数分析%DIMENSION ANALYSIS ON A CLASS OF BUSH TYPE FRACTAL SURFACES
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
In this paper,the authors construct a class of fractal surfaces,Bush type surfaces,based on the Bush type functions.The Box dimension,Packing dimension and Hausdorff dimension of such surfaces are investigated.
Improving the Bin Packing Heuristic through Grammatical Evolution Based on Swarm Intelligence
Directory of Open Access Journals (Sweden)
Marco Aurelio Sotelo-Figueroa
2014-01-01
Full Text Available In recent years Grammatical Evolution (GE has been used as a representation of Genetic Programming (GP which has been applied to many optimization problems such as symbolic regression, classification, Boolean functions, constructed problems, and algorithmic problems. GE can use a diversity of searching strategies including Swarm Intelligence (SI. Particle Swarm Optimisation (PSO is an algorithm of SI that has two main problems: premature convergence and poor diversity. Particle Evolutionary Swarm Optimization (PESO is a recent and novel algorithm which is also part of SI. PESO uses two perturbations to avoid PSO’s problems. In this paper we propose using PESO and PSO in the frame of GE as strategies to generate heuristics that solve the Bin Packing Problem (BPP; it is possible however to apply this methodology to other kinds of problems using another Grammar designed for that problem. A comparison between PESO, PSO, and BPP’s heuristics is performed through the nonparametric Friedman test. The main contribution of this paper is proposing a Grammar to generate online and offline heuristics depending on the test instance trying to improve the heuristics generated by other grammars and humans; it also proposes a way to implement different algorithms as search strategies in GE like PESO to obtain better results than those obtained by PSO.
Performance of high-rate gravel-packed oil wells
Energy Technology Data Exchange (ETDEWEB)
Unneland, Trond
2001-05-01
Improved methods for the prediction, evaluation, and monitoring of performance in high-rate cased-hole gravel-packed oil wells are presented in this thesis. The ability to predict well performance prior to the gravel-pack operations, evaluate the results after the operation, and monitor well performance over time has been improved. This lifetime approach to performance analysis of gravel-packed oil wells contributes to increase oil production and field profitability. First, analytical models available for prediction of performance in gravel-packed oil wells are reviewed, with particular emphasis on high-velocity flow effects. From the analysis of field data from three North Sea oil fields, improved and calibrated cased-hole gravel-pack performance prediction models are presented. The recommended model is based on serial flow through formation sand and gravel in the perforation tunnels. In addition, new correlations for high-velocity flow in high-rate gravel-packed oil wells are introduced. Combined, this improves the performance prediction for gravel-packed oil wells, and specific areas can be targeted for optimized well design. Next, limitations in the current methods and alternative methods for evaluation and comparison of well performance are presented. The most widely used parameter, the skin factor, remains a convenient and important parameter. However, using the skin concept in direct comparisons between wells with different reservoir properties may result in misleading or even invalid conclusions. A discussion of the parameters affecting the skin value, with a clarification of limitations, is included. A methodology for evaluation and comparison of gravel-packed well performance is presented, and this includes the use of results from production logs and the use of effective perforation tunnel permeability as a parameter. This contributes to optimized operational procedures from well to well and from field to field. Finally, the data sources available for
Nonequilibrium hard-disk packings with controlled orientational order
International Nuclear Information System (INIS)
This paper addresses one of the fundamental questions in the theory of hard-disk packings--how order within a system relates to packing density. The algorithm presented is a seed-based, growth protocol in which new disks are added sequentially to the surface of a growing cluster. The angular position of the new disk is chosen based on the minimization of an objective function designed to control order, as measured by the global bond-orientational order parameter ψ6, which varies between 0 and 1 (with 1 indicating perfect hexagonal close-packed order). Modifying the objective function allows the final packing fraction to be biased while maintaining tight control over ψ6. Inside of the range 0≤ψ6≤0.70, the targeted order parameter ψ6 is achieved to within two decimal places of accuracy. Furthermore, it is found that random structures (ψ6∼0.01) can be generated with packing fractions in the range 0.40≤η≤0.77. Interestingly, the algorithm can produce nonequilibrium hard-disk configurations that are considerably more disordered than those typical of the equilibrium fluid. (c) 2000 American Institute of Physics
The progress in the study of Arctic pack ice ecology
Institute of Scientific and Technical Information of China (English)
何剑锋; 王桂忠; 蔡明红; 李少菁
2004-01-01
The sea ice community plays an important role in the Arctic marine ecosystem. Because of the predicted environmental changes in the Arctic environment and specifically related to sea ice, the Arctic pack ice biota has received more attention in recent years using modern ice-breaking research vessels. Studies show that the Arctic pack ice contains a diverse biota and besides ice algae, the bacterial and protozoan biomasses can be high. Surprisingly high primary production values were observed in the pack ice of the central Arctic Ocean. Occasionally biomass maximum were discovered in the interior of the ice floes, a habitat that had been ignored in most Arctic studies. Many scientific questions, which deserve special attention, remained unsolved due to logistic limitations and the sea ice characteristics. Little is know about the pack ice community in the central Arctic Ocean. Almost no data exists from the pack ice zone for the winter season. Concerning the abundance of bacteria and protozoa, more studies are needed to understand the microbial network within the ice and its role in material and energy flows. The response of the sea ice biota to global change will impact the entire Arctic marine ecosystem and a long-term monitoring program is needed. The techniques, that are applied to study the sea ice biota and the sea ice ecology, should be improved.
Test apparatus for ITER blanket pebble packing behavior
International Nuclear Information System (INIS)
Current Japanese design for ITER Driver Blanket consists of three breeder layers, nine multiplier layers and five cooling panels. The breeder layers and the multiplier layers contain 1 mm diameter spheres of Li2O and Be, respectively. The heat transfer in such 'Pebble Layered Blanket' is largely affected by the packing fraction of the pebbles which can be easily changed by the vibration during the operation. The packing fraction of the pebbles are expected to be as high as possible on the view point of nuclear heat design to maintain the optimum temperature of the breeder layer. Thus, it is necessary to establish the stable packed bed of the breeder and multiplier. The present experimental apparatus was fabricated for the engineering tests with the partial model of Japanese blanket. Test apparatus consists of stainless steel test panels, transparent plastic test panels, vibrators and measurement instruments. The apparatus can examine various parameters of sphere packed beds such as packing fraction, panels deformation, loading weight at the bottom of the panels and so on under various vibrating conditions. (author)
Important notice for Windows 2000 Service Pack 3 computers
The NICE Team
2005-01-01
Microsoft is ending support for Windows 2000 Service Pack 3, which was introduced in 2002. As a consequence, computers running Windows 2000 Service Pack 3 (or older versions1)) must be updated. It is recommended that Windows 2000 computers be re-installed with Windows XP Service Pack 2 (see http://cern.ch/Win/Services/Installation/Diane). If this is not possible for compatibility reasons, Windows 2000 Service Pack 4 must be installed to ensure the computers continue to receive security patches (see http://cern.ch/Win/Docs/2000SP4). In the next few days, NICE 2000 computers requiring an update will receive a pop-up window with instructions. Users requiring help with the update can contact Helpdesk@cern.ch or call 78888. If your computer needs to be updated you are recommended to read the additional information available at http://cern.ch/Win/Docs/2000SP3. The NICE Team 1) To determine your Windows service pack version, use the Start' button and select Run'. In the new window that open...
Important notice for Windows 2000 Service Pack 3 computers
The NICE Team
2005-01-01
Microsoft is ending support for Windows 2000 Service Pack 3, which was introduced in 2002. As a consequence, computers running Windows 2000 Service Pack 3 (or older versions1) ) must be updated. It is recommended that Windows 2000 computers be re-installed with Windows XP Service Pack 2 (see http://cern.ch/Win/Services/Installation/Diane). If this is not possible for compatibility reasons, Windows 2000 Service Pack 4 must be installed to ensure the computers continue to receive security patches (see http://cern.ch/Win/Docs/2000SP4). In the next few days, NICE 2000 computers requiring an update will receive a pop-up window with instructions. Users requiring help with the update can contact Helpdesk@cern.ch or call 78888. If your computer needs to be updated you are recommended to read the additional information available at http://cern.ch/Win/Docs/2000SP3. The NICE Team 1) To determine your Windows service pack version, use the ‘Start' button and select ‘Run'. In the new window that opens, type ‘wi...
Bernal's road to random packing and the structure of liquids
Finney, John L.
2013-11-01
Until the 1960s, liquids were generally regarded as either dense gases or disordered solids, and theoretical attempts at understanding their structures and properties were largely based on those concepts. Bernal, himself a crystallographer, was unhappy with either approach, preferring to regard simple liquids as 'homogeneous, coherent and essentially irregular assemblages of molecules containing no crystalline regions'. He set about realizing this conceptual model through a detailed examination of the structures and properties of random packings of spheres. In order to test the relevance of the model to real liquids, ways had to be found to realize and characterize random packings. This was at a time when computing was slow and in its infancy, so he and his collaborators set about building models in the laboratory, and examining aspects of their structures in order to characterize them in ways which would enable comparison with the properties of real liquids. Some of the imaginative - often time consuming and frustrating - routes followed are described, as well the comparisons made with the properties of simple liquids. With the increase of the power of computers in the 1960s, computational approaches became increasingly exploited in random packing studies. This enabled the use of packing concepts, and the tools developed to characterize them, in understanding systems as diverse as metallic glasses, crystal-liquid interfaces, protein structures, enzyme-substrate interactions and the distribution of galaxies, as well as their exploitation in, for example, oil extraction, understanding chromatographic separation columns, and packed beds in industrial processes.
Studies of Particle Packings in Mixtures of Pharmaceutical Excipients
Bentham, Craig; Dutt, Meenakshi; Hancock, Bruno; Elliott, James
2005-03-01
Pharmaceutical powder blends used to generate tablets are complex multicomponent mixtures of the drug powder and excipients which facilitate the delivery of the required drug. The individual constituents of these blends can be noncohesive and cohesive powders. We study the geometric and mechanical characteristics of idealized mixtures of excipient particle packings, for a small but representative number of dry noncohesive particles, generated via gravitational compaction followed by uniaxial compaction. We discuss particle packings in 2- and 3- component mixtures of microcrystalline cellulose (MCC) & lactose and MCC, starch & lactose, respectively. We have computed the evolution of the force and stress distributions in monodisperse and polydisperse mixtures comprised of equal parts of each excipient; comparisons are made with results for particles packings of pure blends of MCC and lactose. We also compute the stress-strain relations for these mixtures. In order to obtain insight into details of the particle packings, we calculate the coordination number, packing fraction, radial distribution functions and contact angle distributions for the various mixtures. The numerical experiments have been performed on spheroidal idealizations of the excipient grains using Discrete Element Method simulations (Dutt et al., 2004 to be published).
Spectral Action Models of Gravity on Packed Swiss Cheese Cosmology
Ball, Adam
2015-01-01
We present a model of (modified) gravity on spacetimes with fractal structure based on packing of spheres, which are (Euclidean) variants of the Packed Swiss Cheese Cosmology models. As the action functional for gravity we consider the spectral action of noncommutative geometry, and we compute its asymptotic expansion on a space obtained as an Apollonian packing of 3-dimensional spheres inside a 4-dimensional ball. Using information from the zeta function of the Dirac operator of the spectral triple, we show that the leading terms in the asymptotic expansion of the spectral action consist of a zeta regularization of the divergent sum of the leading terms of the spectral actions of the individual spheres in the packing, which accounts for the contribution of the points 1 and 3 in the dimension spectrum (as in the case of a 3-sphere). There is also an additional term coming from the residue at the additional point in the dimension spectrum that corresponds to the packing constant. It detects the fractality of t...
Aheuristic Algorithm for Berth Scheduling Problem in Container Ports
Institute of Scientific and Technical Information of China (English)
张海滨
2011-01-01
In this paper,the berth scheduling problem is transformed into a special two-dimensional packing problem with some constraints.A nonlinear programming model for the problem is established,and a heuristic algorithm is proposed to solve the model.Simulation
Ruiz, Victor G.; Liu, Wei; Tkatchenko, Alexandre
2016-01-01
Modeling the adsorption of atoms and molecules on surfaces requires efficient electronic-structure methods that are able to capture both covalent and noncovalent interactions in a reliable manner. In order to tackle this problem, we have developed a method within density-functional theory (DFT) to model screened van der Waals interactions (vdW) for atoms and molecules on surfaces (the so-called DFT+vdWsurf method). The relatively high accuracy of the DFT+vdWsurf method in the calculation of both adsorption distances and energies, as well as the high degree of its reliability across a wide range of adsorbates, indicates the importance of the collective electronic effects within the extended substrate for the calculation of the vdW energy tail. We examine in detail the theoretical background of the method and assess its performance for adsorption phenomena including the physisorption of Xe on selected close-packed transition metal surfaces and 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) on Au(111). We also address the performance of DFT+vdWsurf in the case of non-close-packed surfaces by studying the adsorption of Xe on Cu(110) and the interfaces formed by the adsorption of a PTCDA monolayer on the Ag(111), Ag(100), and Ag(110) surfaces. We conclude by discussing outstanding challenges in the modeling of vdW interactions for studying atomic and molecular adsorbates on inorganic substrates.
Classes and Theories of Trees Associated with a Class Of Linear Orders
DEFF Research Database (Denmark)
Goranko, Valentin; Kellerman, Ruaan
2011-01-01
classes of trees and between their corresponding first-order theories. We then obtain some general results about the axiomatization of the first-order theories of some of these classes of trees in terms of the first-order theory of the generating class C, and indicate the problems obstructing such general...... results for the other classes. These problems arise from the possible existence of nondefinable paths in trees, that need not satisfy the first-order theory of C, so we have started analysing first order definable and undefinable paths in trees....
Problems over Information Systems
Chikalov, Igor
2011-01-01
The problems of estimation of the minimum average time complexity of decision trees and design of efficient algorithms are complex in general case. The upper bounds described in Chap. 2.4.3 can not be applied directly due to large computational complexity of the parameter M(z). Under reasonable assumptions about the relation of P and NP, there are no polynomial time algorithms with good approximation ratio [12, 32]. One of the possible solutions is to consider particular classes of problems and improve the existing results using characteristics of the considered classes. © Springer-Verlag Berlin Heidelberg 2011.
International Nuclear Information System (INIS)
The demand for hydrogen energy has increased tremendously in recent years essentially because of the increase in the word energy consumption as well as recent developments in fuel cell technologies. The energy information administration has projected that world energy consumption will increase by 59% over the next two decades, from 1999 to 2020, in which the largest share is still dominated by fossil fuels (oil, natural gas and coal). Carbon dioxide (CO2) emissions resulting from the combustion of these fossil fuels currently are estimated to account for three-fourth of human-caused CO2 emissions worldwide. Greenhouse gas emission, including CO2, should be limited, as recommended at the Kyoto Conference, Japan, in December 1997. In this regard, hydrogen (H2) has a significant future potential as an alternative fuel that can solve the problems of CO2 emissions as well as the emissions of other air contaminants. One of the techniques to produce hydrogen is by reforming of hydrocarbons or biomass. Crude ethanol (a form of biomass, which essentially is fermentation broth) is easy to produce, is free of sulphur, has low toxicity, and is also safe to handle, transport and store. In addition, crude ethanol consists of oxygenated hydrocarbons, such as ethanol, lactic acid, glycerol, and maltose. These oxygenated hydrocarbons can be reformed completely to H2 and CO2, the latter of which could be separated from H2 by membrane technology. This provides for CO2 capture for eventual storage or destruction. In the case of using crude ethanol, this will result in negative CO2, emissions. In this paper, we conducted experimental work on production of hydrogen by the catalytic reforming of crude ethanol over a commercial promoted Ni-based catalyst in a packed bed tubular reactor as well as a packed bed membrane reactor. As well, a rigorous numerical model was developed to simulate this process in both the catalytic packed bed tubular reactor and packed bed membrane reactor. The
International Nuclear Information System (INIS)
Purpose: To discuss the juridical basis for CT examinations of cocaine body packers and to evaluate the clinical implementation of a tube current reduction-based low-dose CT protocol. Materials and Methods: A literature search was performed to discuss the legal basis regarding the problem, the procedures, the potential harm and the proportionality. Retrospective evaluation of 8 patients who had undergone a low-dose CT scan (body mass index 2 30 mAs; > 25 kg/m2 60 mAs) during the time period from February until October 2009 in order to exclude or to assess remaining cocaine body packs was approved by the institutional review board. The detectability and condition of the body packs were analyzed. Effective doses were calculated. Results: German jurisdiction does not distinguish between plain film X-ray and CT examinations. Both plain film X-ray and CT examination require a judicial warrant. However, examination results might still remain valid if a warrant was not requested. In 8 examinations (30 mAs n = 3, 60 mAs n = 5, mean BMI 25.9 ± 3.2.) a total of 34 body packs were correctly identified. The mean density of the body packs was 74.4 ± 31.9 HU (range 17 - 154 HU) with a cocaine content between 22.5 % and 72.8 %. The mean estimated radiation dose was 2.23 ± 0.72 mSv. Conclusion: Although medical legal aspects do not specify the diagnostic procedure to be performed, the high diagnostic accuracy and applied radiation dose reduction could establish low-dose CT as the method of choice for detecting cocaine body packs, thereby potentially avoiding future legal problems. (orig.)
FY-87 packing fabrication techniques (commercial waste form) results
Energy Technology Data Exchange (ETDEWEB)
Werry, E.V.; Gates, T.E.; Cabbage, K.S.; Eklund, J.D.
1988-04-01
This report covers the investigation of fabrication techniques associated with the development of suitable materials and methods to provide a prefabricated packing for waste packages for the Basalt Waste Isolation Project (BWIP). The principal functions of the packing are to minimize container corrosion during the 300 to 1000 years following repository closure and provide long-term control of the release of radionuclides from the waste package. The investigative work, discussed in this report, was specifically conceived to develop the design criteria for production of full-scale prototypical packing rings. The investigative work included the preparation of procedures, the preparation of fabrication materials, physical properties, and the determination of the engineering properties. The principal activities were the preparation of the materials and the determination of the physical properties. 21 refs., 20 figs., 14 tabs.