ppxscal/embedding_network huggingface dataset:
A Simple, Robust Leadtime-Quoting Policy
Authors: Wallace J. Hopp, Melanie Roof Sturgis
Venue: Manufacturing Service Operations Management (2001)

We examine leadtime-quoting polices for minimizing average lead time subject to customer service constraints on fill rate, tardiness, or relative tardiness in simple systems with exponential and normal processing times. By studying the resulting safety leadtimes implied by each policy we gain insight into why some policies perform more robustly with respect to different measures of customer service than do others. This analysis suggests that a simple constant safety leadtime policy should work reasonably well under most conditions. A series of simulation experiments of more complex production environments indicates that the constant safety leadtime policy does indeed exhibit robust performance. This, plus the fact that it is extremely simple to adapt to a wide range of production environments, makes it an attractive basis for real-world leadtime-quoting systems.
Teaching parametric cubic curves with applets
Authors: James Gary, Robert Crawford
Venue: Journal of Computing Sciences in Colleges (2003)

We are investigating the use of Java applets as an instructional aid in a Computer Graphics course. The properties and behaviors of parametric cubic curves are difficult to explain using static media and the mathematics involved often results in student anxiety and disinterest. In an attempt to help the students gain a meaningful understanding of these important concepts, we are developing a series of applets illustrating key concepts. We hope to find the applets effective in a variety of ways; as a demonstration tool during lecture, as an interactive hand-on experimentation tool for the individual student, as well as a key component in a web-based learning environment.Currently we are illustrating various aspects of Bezier Curves, but plan to extend the set of applets to include other parametric curves and perhaps surfaces. Interactive applets allow students to observe curve behavior as control points are moved and to observe the bounding convex hull property. Such applets are easy to write and commonly found on the web. We are attempting a more intensive learning experience by illustrating the relationship between blending functions (the Bernstein Polynomials) and the curve shape. The de Castlejau approach to finding a point on the curve and general curve subdivision are also illustrated. We furthermore attempt to explain different types of continuity at the juncture of two curves by allowing the student to experiment with curves under various continuity constraints.
Modeling and Analysis of Discrete-Time Multiserver Queues with Batch Arrivals: GIX/Geom/m
Authors: M. L. Chaudhry, U. C. Gupta, V. Goswami
Venue: INFORMS Journal on Computing (2001)

Multiserver queues are often encountered in telecommunication systems and have special importance in the design of ATM networks. This paper analyzes a discrete-time multiserver queueing system with batch arrivals in which the interbatch and service times are, respectively, arbitrarily and geometrically distributed. Using supplementary-variable and embedded-Markov-chain techniques, the queue is analyzed only for the early arrival system. Since the late arrival system can be discussed similarly, it is not considered here. In addition to developing relations among state probabilities at prearrival, arbitrary, and outside observer's observation epochs, the numerical evaluation of state probabilities is also discussed. It is also shown that, in the limiting case, the relations developed here tend to continuous-time counterparts. Further, the waiting-time distribution of a random customer of a batch is obtained. Finally, in some cases simulation experiments have been performed to validate our results.
Weyl transforms associated with Laguerre functions
Authors: Azza Dachraoui
Venue: Journal of Computational and Applied Mathematics (2003)

We consider two partial differential operators D1 and D2 having eigenfunctions defined with Laguerre functions. We give the harmonic analysis associated with D1 and D2. We define and study the Wigner transform associated with D1 and D2, and we prove for this transform an inversion formula. Next we consider classes of symbols which allows us to define the Weyl transform associated with D1 and D2. An integral relation between the precedent Weyl and Wigner transforms is given. At last, we study criterions in term of symbols for the boundedness and compactness of this Weyl transform.
Computing the Optimal Replenishment Policy for Inventory Systems with Random Discount Opportunities
Authors: Y. Feng, J. Sun
Venue: Operations Research (2001)

The paper considers the optimal control of a single-item continuous-review inventory system with random demand and discount opportunities. Items can always be purchased with the regular order setup and variable costs. However, when a discount opportunity occurs, they can also be purchased with a different setup cost and a lower variable cost. Demands for individual items and discount opportunities occur according to independent Poisson processes. The paper proposes an algorithm to compute the parameters of the optimal replenishment policy, which has been shown to be an ( r, R, d, D) policy wherer
Efficient topology-aware overlay network
Authors: Marcel Waldvogel, Roberto Rinaldi
Venue: ACM SIGCOMM Computer Communication Review (2003)

Peer-to-peer (P2P) networking has become a household word in the past few years, being marketed as a work-around for server scalability problems and "wonder drug" to achieve resilience. Current widely-used P2P networks rely on central directory servers or massive message flooding, clearly not scalable solutions. Distributed Hash Tables (DHT) are expected to eliminate flooding and central servers, but can require many long-haul message deliveries. We introduce Mithos, an content-addressable overlay network that only uses minimal routing information and is directly suitable as an underlay network for P2P systems, both using traditional and DHT addressing. Unlike other schemes, it also efficiently provides locality-aware connectivity, thereby ensuring that a message reaches its destination with minimal overhead. Mithos provides for highly efficient forwarding, making it suitable for use in high-throughput applications. Paired with its ability to have addresses directly mapped into a subspace of the IPv6 address space, it provides a potential candidate for native deployment. Additionally, Mithos can be used to support third-party triangulation to quickly select a close-by replica of data or services.
Production planning problems in printed circuit board assembly
Authors: Yves Crama, Joris van de Klundert, Frits C. R. Spieksma
Venue: Discrete Applied Mathematics (2002)

This survey describes some of the main optimization problems arising in the context of production planning for the assembly of printed circuit boards. The discussion is structured around a hierarchical decomposition of the planning process into distinct optimization subproblems, addressing issues such as the assignment of board types to machine groups, the allocation of component feeders to individual machines, the determination of optimal production sequences, etc. The paper reviews the literature on this topic with an emphasis on the most recent developments, on the fundamental structure of the mathematical models and on the relation between these models and some 'environmental' variables such as the layout of the shop or the product mix.
Product language in electronic media design
Authors: Steffen Klein
Venue: Ubiquity (2001)

Communication follows function: How products communicate to users and why designers should care.
MIMD-SIMD hybrid system: towards a new low cost parallel system
Authors: Leo Chin Sim, Heiko Schroder, Graham Leedham
Venue: Parallel Computing (2003)

This paper describes a new parallel architectural system which we have called an MIMD-SIMD hybrid system. As the name implies, MIMD-SIMD hybrid system (also denoted as hybrid system in this paper) is a combination of both SIMD and MIMD systems working concurrently to produce an optimal architecture. This new parallel architecture has the capability of achieving speedup rates more than its corresponding MIMD architecture can achieve alone. We introduce our new SIMD concept and also show the contribution of the SIMD on this hybrid system. We have also developed a general formula for determining the speedup of the hybrid system so that accurate predictions can be made on the performance of the hybrid system. A MIMD-SIMD hybrid system was constructed and was used to implement on a visualization algorithm.
Concise descriptions of subsets of structured sets
Authors: Alberto O. Mendelzon, Ken Q. Pu
Venue: Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2003)

We study the problem of economical representation of subsets of structured sets, that is, sets equipped with a set cover. Given a structured set U, and a language L whose expressions define subsets of U, the problem of Minimum Description Length in L (L-MDL) is: "given a subset V of U, find a shortest string in L that defines V".We show that the simple set cover is enough to model a number of realistic database structures. We focus on two important families: hierarchical and multidimensional organizations. The former is found in the context of semistructured data such as XML, the latter in the context of statistical and OLAP databases. In the case of general OLAP databases, data organization is a mixture of multidimensionality and hierarchy, which can also be viewed naturally as a structured set. We study the complexity of the L-MDL problem in several settings, and provide an efficient algorithm for the hierarchical case.Finally, we illustrate the application of the theory to summarization of large result sets, (multi) query optimization for ROLAP queries, and XML queries.
Mobile information re-finding as a continuing dialogue
Authors: Robert G. Capra,  III
Venue: CHI '03 extended abstracts on Human factors in computing systems (2003)

Mobile users have many needs to re-find information across a variety of computing devices, locations, and situations. My research explores two areas to support mobile information re-finding. First, I am investigating how users re-find information first found on the web: how people approach re-finding, what information they recall when trying to re-find, and how they converse about re-finding. Second, I am examining how shared context can be established and utilized between a user and a computer system to improve future re-finding interactions. In this paper, I present two efforts to explore these areas. I briefly describe a prototype system to support mobile information re-finding through a telephone-based voice interface, and then present preliminary results from a study of how people converse when engaging in collaborative information refinding tasks with another person. The results of this study suggest that context plays an important role in re-finding.
The Evolution of a Performance Measurement Project at Rtz
Authors: Graeme S. Pauley, Richard J. Ormerod
Venue: Interfaces (1998)

In 1994, RTZ Corporation plc, the world's largest mining company, tried to reconcile (a) the desire of central management to compare performance across mine sites with (b) the desire of local management to judge performance in their own terms. The company began a project to establish a method of measuring open-pit productive capacity, to spread best practice, and to motivate higher performance. Initially we saw the solution as a simple model of equipment availability using hard OR derived using a participative process based on soft OR. Trials in Australia, Southern Africa, and North America showed that we needed to combine various hard and soft OR methods and to move the emphasis to achieving breakthroughs in performance. The latest trial resulted in an increase in production of over 25 percent in the first year. The results indicate that soft and hard OR methods can be combined to good effect to produce tangible results.
Mixed finite element methods for unilateral problems: convergence analysis and numerical studies
Authors: Patrice Coorevits, Patrick Hild, Khalid Lhalouani, Taoufik Sassi
Venue: Mathematics of Computation (2002)

In this paper, we propose and study different mixed variational methods in order to approximate with finite elements the unilateral problems arising in contact mechanics. The discretized unilateral conditions at the candidate contact interface are expressed by using either continuous piecewise linear or piecewise constant Lagrange multipliers in the saddle-point formulation. A priori error estimates are established and several numerical studies corresponding to the different choices of the discretized unilateral conditions are achieved.
Active Proxy-G: optimizing the query execution process in the grid
Authors: Henrique Andrade, Tahsin Kurc, Alan Sussman, Joel Saltz
Venue: Proceedings of the 2002 ACM/IEEE conference on Supercomputing (2002)

The Grid environment facilitates collaborative work and allows many users to query and process data over geographically dispersed data repositories. Over the past several years, there has been a growing interest in developing applications that interactively analyze datasets, potentially in a collaborative setting. We describe the Active Proxy-G service that is able to cache query results, use those results for answering new incoming queries, generate subqueries for the parts of a query that cannot be produced from the cache, and submit the subqueries for final processing at application servers that store the raw datasets. We present an experimental evaluation to illustrate the effects of various design tradeoffs. We also show the benefits that two real applications gain from using the middleware.
Persuasive technology: using computers to change what we think and do
Authors: B. J. Fogg
Venue: Ubiquity (2002)

Mother Nature knows best--How engineered organizations of the future will resemble natural-born systems.
An analytical method for single level-constrained resourses production problem with constant set-up cost
Authors: S. M. T. Fatemi Ghomi, S. S. Hashemin
Venue: Iranian Journal of Science and Technology (2001)

This paper studies the problem of single level-constrained resources production planning for single item and N-period planning horizon. The considered costs are set-up cost, variable production cost, and holding inventory cost. Optimal solution of the problem can be obtained only through mathematical programming methods. The efficiency of these methods is decreased as the number of periods of planning horizon is increased. Therefore, they are not applicable for practical problems with actual sizes.This paper first improves the heuristic method of Ramsay and Rardin. Then the improvement is led to the development of an efficient method. Under reasonable assumptions, this method is capable to present optimal solution of the problems with actual sizes.
Intelligent next generation WDM optical networks
Authors: Lubo Tancevski
Venue: Information Sciences&mdash;Informatics and Computer Science: An International Journal (2003)

We address issues and parameters related to providing increased interoperability between the IP and the optical layer such that next generation intelligent optical platforms for wavelength switched cross-connected topologies are enabled.
A note on fuzzy Hv-submodules
Authors: B. Davvaz
Venue: The Korean Journal of Computational Applied Mathematics (2003)

The purpose of this paper is to present certain results arising from product between fuzzy Hυ-submodules. In particular, we consider the fundamental relation ε* defined on an Hυ-module and give a property of the fundamental relations and fundamental modules with respect to the fuzzy product of Hυ-modules.
Pattern formation below criticality forced by noise
Authors: Dirk Blömker, Stanislaus Maier-Paape
Venue: Zeitschrift f&uuml;r Angewandte Mathematik und Physik (ZAMP) (2003)

We address the question of pattern formation for equations perturbed by additive noise. To be more precise, we consider an equation of Swift-Hohenberg type, which is a simplified model describing fluids at the convective instability. These equations are considered below criticality, and are therefore stable in the absence of noise. Nevertheless, the stochastic perturbation is strong enough to drive the solution with high probability into regions where pattern of a characteristic wavelength are observed.
The Changeover Scheduling Problem with Time and Cost Considerations: Analytical Results and a Forward Algorithm
Authors: James D. Blocher, Suresh Chand, Kaushik Sengupta
Venue: Operations Research (1999)

In a multiproduct, discrete-item manufacturing environment, it is often more economical to have one "flexible" machine to produce several products rather than to have a dedicated machine for the production of each product. We consider the problem of scheduling multiple products on a single-finite-capacity resource when faced with product-dependent, but sequence-independent, changeover costs and times. The problem horizon is assumed finite and the demand time-varying and known over this horizon. The objective is to find a feasible schedule that meets all demand on time and minimizes the total changeover cost. With the "delivery-on-time-or-else" mentality and the trend toward shorter order-to-delivery lead times, scheduling and managing changeovers has become just that much more important. We first present analytical results to reduce the feasible solution space and then develop a branch-and-bound algorithm to solve this NP-complete problem. Computational results are presented that show that the algorithm can solve realistic size problems in a reasonable amount of time.
First computer languages
Authors: Kris Howell
Venue: Journal of Computing Sciences in Colleges (2003)

The first computer language that a student learns will set the tone for every computer class that follows. The real issue is not what language to teach first, but how to approach the teaching of the language. The ideal class has the following five elements: 1) A special introduction lab to expose the student to the language interface without regard for solving the problem. 2) Structured labs take place throughout the semester. These labs compliment the lecture and clarify current homework assignments. 3) Comprehensive grade sheets that reinforce the required programming skills and concepts of programming. 4) In-class grading exercises that strengthen the student's understanding of all programming requirements. And 5) a constant and timely feedback loop from the instructor to the student. This first computer language course must be designed to develop an appreciation for learning that the students will carry with them throughout their careers. (Denning et. al., 1988)
Adaptive Mesh Methods for One- and Two-Dimensional Hyperbolic Conservation Laws
Authors: Huazhong Tang, Tao Tang
Venue: SIAM Journal on Numerical Analysis (2003)

We develop efficient moving mesh algorithms for one- and two-dimensional hyperbolic systems of conservation laws. The algorithms are formed by two independent parts: PDE evolution and mesh-redistribution. The first part can be any appropriate high-resolution scheme, and the second part is based on an iterative procedure. In each iteration, meshes are first redistributed by an equidistribution principle, and then on the resulting new grids the underlying numerical solutions are updated by a conservative-interpolation formula proposed in this work. The iteration for the mesh-redistribution at a given time step is complete when the meshes governed by a nonlinear equation reach the equilibrium state. The main idea of the proposed method is to keep the mass-conservation of the underlying numerical solution at each redistribution step. In one dimension, we can show that the underlying numerical approximation obtained in the mesh-redistribution part satisfies the desired TVD property, which guarantees that the numerical solution at any time level is TVD, provided that the PDE solver in the first part satisfies such a property. Several test problems in one and two dimensions are computed using the proposed moving mesh algorithm. The computations demonstrate that our methods are efficient for solving problems with shock discontinuities, obtaining the same resolution with a much smaller number of grid points than the uniform mesh approach.
Computing unrooted maximum subtrees in sub-quartic time
Authors: T. W. Lam, W. K. Sung, H. F. Ting
Venue: Nordic Journal of Computing (1996)

This paper presents an O(n1.75+o(1)) time algorithm for the Unrooted Maximum Agreement Subtree (UMAST) problem: Given a set A of n items (e.g. species) and two unrooted trees T and T', each with n leaves uniquely labeled by the items of A, we want to compute the largest subset B of A such that the subtrees of T and T' induced by B are isomorphic. The UMAST problem is closely related to some problems in biology, in particular, the one of finding the consensus between evolutionary trees (or phylogenies) of a set of species.
Directional Newton methods in n variables
Authors: Yuri Levin, Adi Ben-Israel
Venue: Mathematics of Computation (2002)

Directional Newton methods for functions f of n variables are shown to converge, under standard assumptions, to a solution of f(x) = 0. The rate of convergence is quadratic, for near-gradient directions, and directions along components of the gradient of f with maximal modulus. These methods are applied to solving systems of equations without reversion of the Jacobian matrix.
Probabilistic Analysis and Practical Algorithms for the Flow Shop Weighted Completion Time Problem
Authors: Philip Kaminsky, David Simchi-Levi
Venue: Operations Research (1998)

In the flow shop weighted completion time problem, a set of jobs has to be processed on m machines. Every machine has to process each one of the jobs, and every job has the same routing through the machines. The objective is to determine a sequence of the jobs on the machines so as to minimize the sum of the weighted completion times of all jobs on the final machine. In this paper, we present a characterization of the asymptotic optimal solution value for general distributions of the job processing times and weights. In particular, we show that the optimal objective value of this problem is asymptotically equivalent to certain single and parallel machine scheduling problems. This characterization leads to a better understanding of the effectiveness of the celebrated weighted shortest processing time algorithm, as well as to the development of an effective algorithm closely related to the profile fitting heuristic, which was previously utilized for flow shop makespan problems. Computational results show the effectiveness of WSPT and this modified profile fitting heuristic on a set of random test problems.
Parallel components for PDEs and optimization: some issues and experiences
Authors: Boyana Norris, Satish Balay, Steven Benson, Lori Freitag, Paul Hovland, Lois McInnes, Barry Smith
Venue: Parallel Computing (2002)

High-performance simulations in computational science often involve the combined software contributions of multidisciplinary teams of scientists, engineers, mathematicians, and computer scientists. One goal of component-based software engineering in large-scale scientific simulations is to help manage such complexity by enabling better interoperability among codes developed by different groups. This paper discusses recent work on building component interfaces and implementations in parallel numerical toolkits for mesh manipulations, discretization, linear algebra, and optimization. We consider several motivating applications involving partial differential equations and unconstrained minimization to demonstrate this approach and evaluate performance.