ppxscal/embedding_network huggingface dataset:
Finite-element analysis of a PBGA assembly under isothermal/mechanical twisting loading
Authors: Q. J. Yang, X. Q. Shi, Z. P. Wang, Z. F. Shi
Venue: Finite Elements in Analysis and Design (2003)

In order to reduce the reliability testing time for new electronic products, a new highly accelerated mechanical-thermal (HAMT) test system has been developed. In this system, a cyclic out-of-plane deformation is imposed on a printed circuit board (PCB) assembly by twisting the PCB mechanically inside a thermal chamber. The combined effects of the mechanical deformation and the coefficient of thermal expansion (CTE) mismatch of different materials accelerate the failure of solder joints, so as to reduce the reliability testing time of the PCB assembly. To verify the test method, HAMT tests of plastic ball grid array (PBGA) assemblies were carried out in an isothermal environment. Finite-element (FE) simulations were conducted to predict the reliability of the PBGA assemblies under the isothermal/mechanical twisting (ITMT) loading condition. In this paper, the simulation results are presented. The failure locations in the PBGA solder joints under the ITMT loading condition are investigated, and the fatigue life of the interconnections is predicted using Darveaux's crack initiation and growth model. The simulation results exhibit a good correlation with the test results.
Ambiguity-Directed Sampling for Qualitative Analysis of Sparse Data from Spatially-Distributed Physical Systems
Authors: Chris Bailey-Kellogg, Naren Ramakrishnan
Venue:  (2001)

A number of important scientific and engineering applications, such as fluid dynamics simulation and aircraft design, require analysis of spatially-distributed data from expensive experiments and complex simulations. In such data-scarce applications, it is advantageous to use models of given sparse data to identify promising regions for additional data collection. This paper presents a principled mechanism for applying domain-specific knowledge to design focused sampling strategies. In particular, our approach uses ambiguities identified in a multi-level qualitative analysis of sparse data to guide iterative data collection. Two case studies demonstrate that this approach leads to highly effective sampling decisions that are also explainable in terms of problem structures and domain knowledge.
Finding Correspondences of Patches by Means of Affine Transformations
Authors: R. Berthilsson
Venue: Proceedings of the International Conference on Computer Vision-Volume 2 - Volume 2 (1999)

In this paper we present a novel method for finding the optimal affine transformation for matching of images. The method requires no feature points, does not rely on normalization of images and can be tuned to highlight interesting parts in the images. Furthermore, the method does not need any derivatives for obtaining the affine transformation and it has a computational cost proportional to n2 logn for n×n images.The problem of finding the optimal affine transformation is solved by an iterative algorithm. In each step a global optimization is performed by the use of FFT. This global characteristic helps the algorithm from getting trapped in a local optimum. Novel theoretical results are presented that show under what restrictions the algorithm can be expected to work properly.Its intended primary use is for reconstruction problems in computer vision. These rely heavily on the establishment of point correspondences in the images. Since the method makes no assumptions on the images it can be used when feature points are difficult to detect. Experiments on real images are included and it is shown that the algorithm is robust and performs well even in difficult situations, with occlusions. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
On Scheduling Meetings
Authors: Robert A. Wagner
Venue:  (1970)

We commment on the problem of assigning papers to time-slots to minimize the time needed for a technical meeting. We claim that this problem is, in abstract, the problem of discovering a minimal coloring of a conflict graph. This approach contrasts with that of Joseph E. Grimes in [1]. Key words and phrases: allocation, conflict matrix, connected component, scheduling, spanning tree, undirected linear graph, graph node coloring, graph vertex coloring.
DENSITY ESTIMATION TECHNIQUES FOR GLOBAL ILLUMINATION
Authors: Bruce Walter
Venue:  (1998)

In this thesis we present the density estimation framework for computing view-independent global illumination solutions. The framework consists of three phases: particle tracing, density estimation, and decimation. Monte Carlo particle tracing is used to accurately simulate the light transport under a general spectral geometric-optics based physical model. Next kernel density estimation is used to reconstruct perceptual illumination functions. Finally decimation is used to optimize the resulting mesh for compactness and rapid interactive display as Gouraud-shaded triangles. The three principal contributions of this work are the framework''s separation of transport and function reconstruction computations, its ability to produce accurate solutions with precisely known error characteristics, and the techniques that we introduce to improve its efficiency and accuracy. Particle tracing''s generality allows us to eliminate or delay many common simplifying assumptions and improves our accuracy and error analysis. Delaying the density estimation until particle tracing is complete allows us to make better use of the expensive particle data. The separation of global transport and local representation computations also reduces the computational complexity of each phase, enhances the framework''s scalability, and exposes abundant opportunities for parallelism. Another advantage is that we can solve directly for the radiant exitance without needing to estimate the more complicated spectral radiance function. Despite its advantages, if naively implemented the framework would be prohibitively expensive. Thus we also introduce several techniques that significantly improve its accuracy and efficiency. These include the separation of luminance and chromaticity bandwidths, perceptually-motivated noise visibility predictors, statistical bias detection techniques to automatically enhance underresolved illumination features, a local polynomial density estimation method to eliminate boundary bias, and wavelength importance sampling to reduce the spectral noise. Results of the framework are shown for some complex environments and compared against measured data for a simple scene. The strength of our framework is that it can simulate a wider variety of lighting effects, with fewer simplifying assumptions, and more precise error analysis that current view-independent methods. Furthermore, because of its accuracy, our density estimation framework solutions are used as reference solutions for judging the quality and effectiveness of more approximate but faster rendering methods.
On the Limit Values of Probabilities for the First Order Properties of Graphs
Authors: Joel Spencer, Lubos Thoma
Venue:  (1997)

Consider the random graph ${\cal G}(n,p),$ where $p=p(n)$ is any threshold function satisfying $p(n) = \Theta(\ln n / n).$ We give a full characterization of the limit values of probabilities of ${\cal G}(n,p)$ having a property $\psi,$ where $\psi$ is any sentence of the first order theory of graphs.
Automated Tool Support for an Emerging International Software Process Assessment Standard
Authors: R. Lok, A. Walker
Venue: Proceedings of the 3rd International Software Engineering Standards Symposium (ISESS '97) (1997)

The Software Process Assessment and Capability Determination (SPICE) Project was established by ISO/IEC JTCI/SC7/WG10 to assist in the development of the emerging ISO standard for Software Process Assessment (ISO/IEC 15504) and to undertake user trials to provide early feedback for revision of the Standard. This paper describes the development of an automated tool to support the conduct of assessments in Phase 2 of the trialling period using the embedded model described in Part 5 of ISO/IEC 15504. The development process and product quality objectives and their validation are described. The impact of user feedback on the evolution of the tool is reviewed. Early experience in the application of the tool for conducting assessments is presented.
k-tuple domination in graphs
Authors: Chung-Shou Liao, Gerard J. Chang
Venue: Information Processing Letters (2003)

In a graph G, a vertex is said to dominate itself and all of its neighbors. For a fixed positive integer k, the k-tuple domination problem is to find a minimum sized vertex subset in a graph such that every vertex in the graph is dominated by at least k vertices in this set. The current paper studies k-tuple domination in graphs from an algorithmic point of view. In particular, we give a linear-time algorithm for the k-tuple domination problem in strongly chordal graphs, which is a subclass of chordal graphs and includes trees, block graphs, interval graphs and directed path graphs. We also prove that the k-tuple domination problem is NP-complete for split graphs (a subclass of chordal graphs) and for bipartite graphs.
Impact of Traffic Shaping in ATM Networks on Video Quality
Authors: Yongdong Wang, Michael Jurczyk
Venue: Proceedings of the 2000 International Workshop on Parallel Processing (2000)

This paper presents the impact of traffic shaping on enhancing the interactive video quality over ATM networks. The effects of the leaky bucket traffic shaper on the video quality are studied under different token buffer rates and token buffer sizes, and the tradeoffs involved are discussed. An enhanced traffic shaper using the early drop mechanism is then introduced. Simulation results show that for delay sensitive applications like interactive video, the combination of traffic shaping and the early drop mechanism improves the video quality significantly compared to VBR video and regular traffic shaping. The influence of different traffic shapers on the cell loss and the cell loss distribution is studied and it is further explored how the cell loss distribution affects the video performance. The comprehensive study shows that the increase in video quality when using traffic shaping with the early drop mechanism comes both from reducing the cell loss and changing the cell loss distribution.
Solvability of multi-point boundary value problem at resonance-part IV
Authors: Bing Liu
Venue: Applied Mathematics and Computation (2003)

In this paper, we consider the following second order ordinary differential equation x'' = f(t, x(t), x'(t)) + e(t), t ∈ (0, 1), (1.1) subject to one of the following boundary value conditions: x(0) = Σi=1m-2 αix(ξi), x(1) = Σj=1n-2 βjx(ηj), (1.2) x(0) = Σi=1m-2 αix(ξi, x'(1) = Σj=1n-2 βjx'(ηj), (1.3) x'(0) = Σi=1m-2 αix'(ξi, x(1) = Σj=1n-2 βjx(ηj), (1.4) where αi (1 ≤ i ≤ m - 2), βj (1 ≤ j ≤ n - 2) ∈ R, 0 < ξ1 < ξ2 < ... < ξm-2 < 1, 0 < η1 < η2 < ... < ηn-2 < 1. When all the αis have no the same sign and all the βjs have no the same sign, some existence results are given for (1.1) with boundary conditions (1.2)-(1.4) at resonance case. We also give some examples to demonstrate our results.
Simulation based design methodology of steel structure members
Authors: F. Papp
Venue: Proceedings of the sixth conference on Computational structures technology (2002)

Design of steel structures is specified by structural codes. The European steel building code prEN Eurocode 3 is under final vote by CEN. From computational technology point of view the so-called interaction design equations are the most important phase of the codes. These equations govern the design of members as well as the bracing system of the structure. The final draft of the basic code was prepared by extended developments carried out by the so-called ECCS/TC8 working group. This expert group has improved the older formula and created a 'new' one. They suggested a new 'three-level' specification. Level 1 formula has the priority on user-friendliness, simplicity and comprehensiveness. Level 2 formula puts the priority to accuracy, consistency and continuity with other standard checks. Level 3 is the most sophisticated technique using efficient software as well as sufficient theoretical knowledge. This approach is used extensively in the calibration of the two other levels. This paper is related to the Level 2 and 3 formulas and proposes simulation based design methodology, which keeps the principal design and safety philosophy of Eurocode 3, but uses modern computational architectures.
Rigorous Testing Using SnapShot
Authors: Michael Factor, Eitan Farchi, Shmuel Ur
Venue: Proceedings of the 8th Israeli Conference on Computer-Based Systems and Software Engineering (1997)

In this paper we introduce a new testing concept called SnapShot. SnapShot is a testing mechanism which is comprised of two components. The first component instruments the program with SnapShot statements which are used to produce a special trace during the program execution. The second component implements post processing on the trace. SnapShot implicitly defines a user defined coverage criterion and supports its implementation. We have applied SnapShot to a variety of areas including serial, parallel and object oriented programs, and VHDL designs.
A High Performance Communication Subsystem for PODOS
Authors: Sudharshan Vazhkudai, Tobin Maginnis
Venue: Proceedings of the 1st IEEE Computer Society International Workshop on Cluster Computing (1999)

PODOS is a performance oriented distributed operating system being developed to harness the performance capabilities of a cluster computing environment. In order to address the growing demand for performance, we are designing a Distributed Operating System (DOS) that can utilize the computing potential of a number of systems. Earlier clustering approaches have traditionally stressed more on resource sharing or reliability and have given lesser priority to performance.PODOS adds just four new components to the existing Linux operating system to make it distributed. These components are a Communication Manager (CM), a Network Manager (NM), a Resource Manager (RM), and Global Interprocess Communication (GIPC). This paper addresses the communication mechanism in PODOS.In any distributed environment, communication appears to be the performance bottleneck. Thus, in PODOS, we have implemented a high-speed communication subsystem that short circuits the network protocol stack, and further performs packet multiplexing (Transmission-Groups) across multiple network interfaces thereby achieving a two-fold performance gain.In this paper we discuss the high-performance communication subsystem in PODOS and further analyze the performance gain achieved by comparing the variants of the PODOSprotocol with traditional networking protocol.
THE RADIATED NOISE FROM ISOTROPIC TURBULENCE REVISITED
Authors: Geoffrey M. Lilley
Venue:  (1993)

The noise radiated from isotropic turbulence at low Mach numbers and high Reynolds numbers, as derived by Proudman (1952), was the first application of Lighthill''s Theory of Aerodynamic Noise to a complete flow field. The theory presented by Proudman involves the assumption of the neglect of retarded time differences and so replaces the second-order retarded-time and space covariance of Lighthill''s stress tensor, T_, and in particular its second time derivative, by the equivalent simultaneous covariance. This assumption is a valid approximation in the derivation of the ^ T_ / t^$ covariance at low Mach numbers, but is not justified when that covariance is reduced to the sum of products of the time derivatives of equivalent second-order velocity covariances as required when Gaussian statistics are assumed. The present paper removes these assumptions and finds that although the changes in the analysis are substantial, the change in the numerical result for the total acoustic power is small. The present paper also considers an alternative analysis which does not neglect retarded times. It makes use of the Lighthill relationship, whereby the fourth-order T_ retarded-time covariance is evaluated from the square of similar second-order covariance, which is assumed known. In this derivation no statistical assumptions are involved. This result, using distributions for the second-order space-time velocity squared covariance based on the Direct Numerical Simulation(DNS) results of both Sarkar and Hussaini(1993) and Dubois(1993), is compared with the re-evaluation of Proudman''s original model. These results are then compared with the sound power derived from a phenomenological model based on simple approximations to the retarded-time/space covariance of T_. Finally the recent numerical solutions of Sarkar and Hussaini(1993) for the acoustic power are compared with the results obtained from the analytic solutions. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
A family of hybrid conjugate gradient methods for unconstrained optimization
Authors: Yu-Hong Dai
Venue: Mathematics of Computation (2003)

Conjugate gradient methods are an important class of methods for unconstrained optimization, especially for large-scale problems. Recently, they have been much studied. This paper proposes a three-parameter family of hybrid conjugate gradient methods. Two important features of the family are that (i) it can avoid the propensity of small steps, namely, if a small step is generated away from the solution point, the next search direction will be close to the negative gradient direction; and (ii) its descent property and global convergence are likely to be achieved provided that the line search satisfies the Wolfe conditions. Some numerical results with the family are also presented.
Fault Tolerance Evaluation Using Two Software Based Fault Injection Methods
Authors: Astrit Ademaj, Petr Grillinger, Pavel Herout, Jan Hlavicka
Venue: Proceedings of the Proceedings of The Eighth IEEE International On-Line Testing Workshop (IOLTW'02) (2002)

A silicon independent C-Based model of the TTP/C protocol was implemented within the EU-founded project FIT. The C-based model is integrated in the C-Sim simulation environment. The main objective of this work is to verify whether the simulation model of the TTP/C protocol behaves in the presence of faults in the same way as the existing hardware prototype implementation. Thus, the experimental results of the software implemented fault injection applied in the simulation model and in the hardware implementation of the TTP/C network have been compared. Fault injection experiments in both the hardware and the simulation model are performed using the same configuration setup, and the same fault injection input parameters (fault injection location, fault type and the fault injection time). The end result comparison has shown a complete conformance of 96.30%, while the cause of the different results was due to hardware specific implementation of the Built-In-Self-Test error detectionmechanisms.
Forward-Tracking: A Technique for Searching Beyond Failure
Authors: Elena Marchiori, Massimo Marchiori, Joost N. Kok
Venue: Proceedings of the 8th International Conference on Tools with Artificial Intelligence (1996)

In many applications, such as decision support, negotiation, planning, scheduling, etc., one needs to express requirements that can only be partially satisfied. In order to express such requirements, we propose a technique called forward-tracking. Intuitively, forward-tracking is a kind of dual of chronological back-tracking: if a program globally fails to find a solution, then a new execution is started from a program point and a state `forward' in the computation tree. This search technique is applied to constraint logic programming, obtaining a powerful extension that preserves all the useful properties of the original scheme. We report on the successful practical application of forward-tracking to the evolutionary training of (constrained) neural networks.
Group communication support for distributed collaboration systems
Authors: Injong Rhee, Shun Yan Cheung, P. W. Hutto, V. S. Sunderam
Venue: Proceedings of the 17th International Conference on Distributed Computing Systems (ICDCS '97) (1997)

The Collaborative Computing Transport Layer (CCTL) is a communication substrate consisting of a suite of multiparty protocols, providing varying service qualities among process groups. CCTL explicitly supports distributed collaborative and multimedia applications. CCTL is based on a two-level group hierarchy. Logical interconnections among entities, called channels, define an efficient and light-weight group mechanism. Channels support a variety of service qualities such as reliability and message ordering. Related channels can also be combined to form sessions, heavy-weight groups which provide a default atomic multicast service. CCTL supports membership protocols tailored to the quality of service offered by a channel, including a relaxed form of virtual synchrony. In this paper, we present three membership protocols and compare and relate our implementations to alternatives. Our two-level architecture allows simple and efficient implementation of the membership protocols.
2D Topological and Direction Relations in the World of Minimum Bounding Circles
Authors: Maytham Safar, Cyrus Shahabi
Venue: Proceedings of the 1999 International Symposium on Database Engineering & Applications (1999)

The representation and processing of spatial queries is important in numerous application domains in the areas of computer-aided design, multimedia databases, spatial and geographic applications. A sample query type in these applications is to find objects that satisfy a specific direction or topological relation with respect to a given object. Due to the large size of these databases and the complexity of geometric algorithms, appropriate indexing techniques and object approximations are crucial. The problem is that the relationships between object approximations are usually a superset of the actual relationships between their corresponding objects, resulting in a number of false hits. A challenge, hence, is to reduce the number of false hits in order to decrease the number of times we invoke the complex geometric algorithms on the actual representations of the objects. In this paper, we describe the support of topological and direction queries using spatial data structures based on the minimum bounding circle approximation {MBC}. By identifying special cases in MBC relations, we propose extra filtering steps to reduce the number of false hits.
A Bibliography of Parallel Debuggers, 1990 Edition
Authors: Cherri M. Pancake, Sue Utter
Venue:  (1990)

A bibliography of over three hundred technical reports, journal and conference papers, and Ph.D. dissertations dealing with parallel and distributed debuggers. Treatments of programming environments, debugging methodology, and techniques for program analysis are included when a significant portion of the publication is devoted to factors influencing the design or implementation of debugging tools.
Epic 1.0 (unconditional) an equational programming language
Authors: H. R. Walters, Jasper F.T Kamperman
Venue:  (1996)

We present EPIC, an equational programming language: its abstract syntax, static and operational semantics, and one of many possible concrete grammars of unconditional EPIC.