ppxscal/embedding_network huggingface dataset:
TIMESTAMPING SCHEMES FOR MPEG-2 SYSTEMS LAYER AND THEIR EFFECT ON RECEIVER CLOCK RECOVERY
Authors: Christos Tryfonas, Anujan Varma
Venue:  (1998)

We propose and analyze several strategies for performing timestamping of an MPEG-2 Transport Stream transmitted over a packet-switched network using the PCR-unaware encapsulation scheme, and analyze their effect on the quality of the recovered clock at the MPEG-2 Systems decoder. When the timestamping scheme is based on a timer with a fixed period, the PCR values in the packet stream may switch polarity deterministically, at a frequency determined by the timer period and the transport rate of the MPEG signal. This, in turn, can degrade the quality of the recovered clock at the receiver beyond acceptable limits. We consider three timestamping schemes for solving this problem: (i) selecting the deterministic timer period to avoid the phase difference in PCR values altogether, (ii) fine-tuning the deterministic timer period to maximize the frequency of PCR polarity changes, and (iii) selecting the timer period randomly to eliminate the deterministic PCR polarity changes. For the case of deterministic timer period, we derive the frequency of the PCR polarity changes as a function of the timer period and the transport rate, and use it to find ranges of the timer period for acceptable quality of the recovered clock. We also analyze a random timestamping procedure based on a random telegraph process and obtain lower bounds on the rate of PCR polarity changes such that the recovered clock does not violate the PAL/NTSC clock specifications. The analytical results are verified by simulations with both synthetic and actual MPEG-2 Transport Streams sent to an MPEG-2 Systems decoder.
Making Cassandra Parallel and Distributed
Authors: I. D. Craig
Venue:  (1991)

This brief set of notes outline ways in which the author''s cassandra architecture can be implemented as a parallel or distributed system.
Efficient Load Balancing Techniques for Image Analysis on an M-SIMD Machine
Authors: Y. Zheng, Darren J. Kerbyson, Graham R. Nudd
Venue:  (1992)

The computational requirements for the real time processing of image sequences is sufficiently high that some form of parallel hardware is essential. In the analysis of a sequence of images the areas of interest are moving objects which usually occupy only small distinct areas within the full field of view. A single instruction multiple data (SIMD) machine has considerable advantages for these types of operations where there is a high requirement for data parallel processing. However, on conventional SIMD machines, only the processors to which the moving objects are mapped onto have significant work-load. The remaining processors are idle during most of the processing period resulting in significant load imbalance and poor utilisation. We describe here load balancing techniques for a Multiple-SIMD (M-SIMD) machine, consisting of a number of small conventional SIMD arrays (patches) connected together to form a larger M-SIMD array. Each SIMD patch can perform independent computations. Using the M-SIMD configuration idle processors can be re-allocated to process active regions of other images from an image sequence or from multiple sensors, significantly increasing the throughput and flexibility of the system. A TvotingU algorithm is presented for the calculation of the minimum number of patches the object is mapped onto along with a heuristic (near optimum) patch allocation process. Key words: Load balancing, Image analysis, Multiple-SIMD architecture
A Geometric Problem in Simplicial Cones with Applications to Linear Complementarity Problems
Authors: Katta G. Murty, Layne T. Watson, Leroy M. Kelly
Venue:  (1986)

We consider the following geometric question: suppose we are given a simplicial cone K in R^n. Can we find a point @) in the interior of K satisfying the property that the orthogonal projection of @) onto the linear hull of every face of K is in the relative interior of that fence? This question plays an important role in determining whether a certain class of linear complementarity problems (LCP ''s) can be solved efficiently by a pivotal algorithm. The answer to this question is always in the affirmative if n=2, but not so for n=3. We establish some conditions for the answer to this question to be yes, and relate them to other well known properties of square matrices. e.g., world: simplicial cones, orthogonal projections, faces, linear complementarity problem, LCP, pivotal algorithms, P-matrices, symmetric positive definite matrices, 2-matrices, M-matrices.
Using Implicit Context to Ease Software Evolution and Reuse
Authors: Robert J. Walker, Gail C. Murphy
Venue:  (1999)

Software systems should consist of simple, conceptually clean components interacting along narrow, well-defined paths. All too often, this is not reality: complex components end up interacting for reasons unrelated to the functionality they provide. We refer to knowledge within a component that is not conceptually required for the individual behaviour of that component as extraneous embedded knowledge (EEK). EEK creeps in to a system in many forms, including dependences upon particular names and the passing of extraneous parameters. This paper proposes implicit context as a means for reducing EEK in systems. Implicit context combines a mechanism to reflect upon what has happened in a system through queries on the call history with a mechanism for altering calls to and from a component. We demonstrate the benefits of implicit context by describing its use to reduce EEK in the Java Swing library.
Paper chase revisited: a real world game meets hypermedia
Authors: Susanne Boll, Jens Krösche, Christian Wegener
Venue: Proceedings of the fourteenth ACM conference on Hypertext and hypermedia (2003)

In this short paper, we present a location aware mobile game which lets users play a paper chase game on a mobile device. By using their physical movement and location in the real world's space the players navigate in the virtual paper chase game and solve riddles on their way. The game is realized as a hypermedia document in which geo-referenced hyperlinks on a map lead to the hypermedia documents that form the riddles that are to be solved at the different physical checkpoints. Traversal of the document is carried out by physical movement/approaching of the GPS-located player achieving a spatial navigation to the checkpoints of the game. The current state of the players is tracked and monitored by the game server. The game is realized with wireless handheld devices together with GPS receivers in a wireless communication net utilising Web infrastructure.
Optimistic Virtual Synchrony
Authors: Jeremy Sussman, Idit Keidar, Keith Marzullo
Venue:  (1999)

Group communication systems are powerful building blocks that facilitate the development of fault-tolerant distributed applications. Such systems generally run in an asynchronous fault-prone environment, and provide semantics (called Virtual Synchrony) that mask the asynchrony and unreliability of the environment. In order to implement Virtual Synchrony semantics, group communication systems typically impose blocking periods during which applications are not allowed to send messages. This paper presents a novel form of group communication, Optimistic Virtual Synchrony (OVS). OVS allows applications to send messages during periods in which existing group communication services block, by making optimistic assumptions on the network connectivity. Optimistic Virtual Synchrony allows applications to determine the policy as to when messages sent optimistically should be delivered and when they should be discarded. Thus, OVS gives applications fine-grain control over the specific semantics they require, and does not impose costs for enforcing any semantics that they do not require. At the same time, OVS provides a single easy-to-use interface for all applications. The paper presents several examples of applications that may exploit OVS and empirical results that show the performance benefits of using OVS.
Simple Algorithms for the On-Line Multidimensional Dictionary and Related Problems
Authors: Teofilo F. Gonzalez
Venue:  (1998)

The on-line multidimensional dictionary problem consists of executing \mbox{on-line} any sequence of the following operations: INSERT($p$), DELETE($p$) and MEMBERSHIP($p$), where $p$ is any (ordered) $d$-tuple (or string with $d$ elements, or points in $d$-space where the dimensions have been ordered). We introduce a clean structure based on balanced binary search trees, which we call multidimensional balanced binary search trees, to represent the set of $d$-tuples. We present algorithms for each of the above operations that take $O(d + \log n)$ time, where $n$ is the current number of $d$-tuples in the set, and each INSERT and DELETE operation requires no more than a constant number of rotations. Our structure requires $dn$ words to represent the input, plus $O(n)$ pointers and data indicating the first component where pairs of $d$-tuples differ. This information, which can be easily updated, enables us to test for MEMBERSHIP efficiently. Other operations that can be performed efficiently in our multidimensional balanced binary search trees are: print in lexicographic order ($O(dn)$ time), find the (lexicographically) smallest or largest $d$-tuple ($O(\log n)$ time), and concatenation ($O(d + \log n)$ time). Finding the (lexicographically) $k^{th}$ smallest or largest $d$-tuple can also be implemented efficiently ($O(\log n)$ time), at the expense of adding an integer value at each node.
Architecture-Level Compact Thermal R-C Modeling
Authors: M. Barcella, W. Huang, K. Skadron, M. R. Stan
Venue:  (2002)

Architectural thermal modeling of high performance VLSI systems is of special importance in order to achieve reliable and power-saving system designs. In this paper, we present a novel, computation-efficient methodology for architectural level compact thermal modeling. The RC thermal models derived from this methodology are based on the layout of micro-architectural level functional blocks such as caches, execution units, and register files, etc. We utilize the duality between thermal and electrical circuit to perform electro-thermal simulations of both steady state and transient thermal responses of different blocks that dissipate different amounts of power. Temperature profiles derived from this modeling technique are compared with those derived from computation-intensive FEM/FDM tools. The model is both extremely fast and accurate, less than 4% error. This modeling methodology can then be adopted for architectural level VLSI design tools to perform fast electro-thermal simulations.
Unsupervised Image Segmentation
Authors: Alison A. Dingle, Mark W. Morrison
Venue:  (1996)

Abstract unavailable.
Non-linear analysis of steel I-girders curved in-plane under a uniformly distributed load
Authors: M. A. Bradford, B. Uy, Y. L. Pi
Venue: Proceedings of the eighth international conference on The application of artificial intelligence to civil and structural engineering computing (2001)

This paper presents a finite element model for undertaking a nonlinear elastic and inelastic analysis of beams curved in-plan, and uses it to investigate the elastic and inelastic behaviour of unpropped composite steel and concrete I-section girders curved in-plan during construction. The finite element model is effective, efficient and accurate. Only a few curved beam elements are sufficient to predict the structural behaviour of curved I-girders accurately. It is found that the traditional linear elastic and plastic analyses are not adequate in predicting the deformations and load carrying capacity of composite steel and concrete I-section curved girders during construction. "Flexural-torsional buckling analysis" only predicts a hypothetical condition of neutral equilibrium, and nonlinear elastic and inelastic-plastic analyses are needed to predict the structural behaviour of curved girders. It is also found that excessive deformations and/or failure may occur during construction, and some measures may need to be taken to prevent the attainment of these limit states in composite curved girders during construction.
Spatial and Spectral Description of Stationary Gaussian Fractals
Authors: R. Rensink
Venue:  (1988)

A general treatment of stationary Gaussian fractals is presented. Relations are established between the fractal properties of an $n$-dimensional random field and the form of its correlation function and power spectrum. These relations are used to show that the second-order parameter $H$ commonly used to describe fractal texture (e.g., in [4][5]) is insufficient to characterize all fractal aspects of the field. A larger set of measures --- based on the power spectrum --- is shown to provide a more complete description of fractal texture. \n Several interesting types of ``non-fractal'''' self-similarity are also developed. These include a generalization of the fractional Gaussian noises of Mandelbrot and van Ness [6], as well as a form of ``locally'''' self-similar behaviour. It is shown that these have close relations to the Gaussian fractals, and consequently, that textures containing these types of self-similarity can be described by the same set of measures as used for fractal texture. 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 Simple Primal Algorithm for Intersecting 3-Polyhedra in Linear Time
Authors: Andrew K. Martin
Venue:  (1991)

This thesis presents, in full, a simple linear time algorithm for intersecting two convex 3-polyhedra P and Q. This differs from the first such algorithm -- due to Chazelle -- in that it operates entirely in primal space, whereas Chazelle''s algorithm relies heavily on duality transforms. We use the hierarchical representations of polyhedra due to Dobkin and Kirkpatrick to induce a cell complexes between coarse approximations, P^k and P_k of P satisfying P_k subset-of P subset-of P^k, and similar approximations Q^k and Q_k of Q satisfying Q_k subset-of Q subset-of Q^k. We show that the structure of such complexes allows intersection queries to be answered efficiently. In particular, the sequence of cells intersected by a ray can be identified in time proportional to the length of the sequence. The algorithm operates by recursively computing the intersections: P^k intersect Q_k and P_k intersect Q^k . Then edges of the union of approximations P intersect Q^k and Q intersect P^k are traversed by tracing their intersection with the two cell complexes. We show that each such edge can be traversed in constant time. In the process, most of the edges of P intersect Q which lie simultaneously on the boundary of P and Q will be traced. We show that the total time needed to construct those which remain is linear in the size of P and Q . Though based on the same general principles, the algorithm presented here is somewhat simpler than that described by Chazelle, which uses only the cell complexes induced by the inner hierarchical representations of P and Q . By extending Chazelle''s search structure to the space exterior to the given polyhedra, we avoid having to operate simultaneously in primal and dual spaces. This permits us to conceptualise the algorithm as traversing the edges of the boundary of (P intersect Q^k) union (Q intersect P^k). As a side effect, we avoid one half of Chazelle''s recursive calls, which leads to a modest improvement in the asymptotic constants.
Randomized Distributed Computing on Rings
Authors: Lisa Higham
Venue:  (1989)

The communication complexity of fundamental problems in distributed computing on an asynchronous ring are examined from both the algorithmic and lower bound perspective. A detailed study is made of the effect on complexity of a number of assumptions about the algorithms. Randomization is shown to influence both the computability and complexity of several problems. Communication complexity is also shown to exhibit varying degrees of sensitivity to additional parameters including admissibility of error, kind of error, knowledge of ring size, termination requirements, and the existence of identifiers. \n A unified collection of formal models of distributed computation on asynchronous rings is developed which captures the essential characteristics of a spectrum of distributed algorithms --- those that are error free (deterministic, Las Vegas, and nondeterministic) and those that err with small probability (Monte Carlo and nondeterministic/probabilistic). The nondeterministic and nondeterministic/probabilistic models are introduced as natural generalizations of the Las Vegas and Monte Carlo models respectively, and prove useful in deriving lower bounds. The unification helps to clarify the essential differences between the progressively more general notions of a distributed algorithm. In addition, the models reveal the sensitivity of various problems to the parameters listed above. \n Complexity bounds derived using these models typically vary depending on the type of algorithm being investigated. The lower bounds are complemented by algorithms with matching complexity while frequently the lower bounds hold on even more powerful models than those required by the algorithms. \n Among the algorithms and lower bounds presented are two specific results which stand out because of their relative significance. \n\begin{enumerate} \item If $g$ is any nonconstant cyclic function of n variables. then any nondeterministic algorithm for computing $g$ on an anonymous ring of size $n$ has complexity $\Omega (n \sqrt{\log n})$ bits of communication; and. there is a is nonconstant cyclic boolean function $f$, such that f can be computed by a Las Vegas algorithm in $O (n \sqrt{\log n})$ expected bits of communication on a ring of size $n$. \n\item The expected complexity of computing AND (and a number of other natural functions) on a ring of fixed size n in the Monte Carlo model is \( \Theta (n \min \{ \log n, \log \log ( 1 / \epsilon ) \} ) \) messages and bits where $\epsilon $ is the allowable probability of error. \end{enumerate}
Image Segmentation Using Multiresolution Fourier Transform
Authors: C. Li, R. G. Wilson
Venue:  (1995)

In this report, the Multiresolution Fourier Transform (MFT) is utilised as an approach to the segmentation of images based on the analysis of local properties in the spatial frequency domain. Five major steps are adopted to implement the segmentation of images in this work.
ACCURATE AND EFFICIENT FAULT SIMULATION OF REALISTIC CMOS NETWORK BREAKS
Authors: Haluk Konuk, F. J Ferguson
Venue:  (1994)

We present a new fault simulation algorithm for realistic break faults in the p-networks and n-networks of static CMOS cells. We show that Miller effects can invalidate a test just as charge sharing can, and we present a new charge-based approach that efficiently and accurately predicts the worst case effects of Miller capacitances and charge sharing together. Results on running our fault simulator on ISCAS85 benchmark circuits are provided.
Faster Solutions for Exact Hitting and Exact SAT
Authors: L. Drori, D. Peleg
Venue:  (1999)

This paper considers a number of NP-complete problems, and provides faster algorithms for solving them. The solutions are based on a recursive partitioning of the problem domain, and careful elimination of some of the branches along the search without actually checking them. The time complexity of the proposed algorithm is of the form O(2en) for constant 0 > e > 1, where n is the output size of the problem. In particular, such algorithms are presented for the Exact SAT and Exact Hitting Set problems with e = 0.2985. Both algorithms improve on previous ones proposed in the literature.
Multidisciplinary Optimization of a Supersonic Transport Using Design of Experiments Theory and Response Surface Modeling
Authors: Giunta Anthony A., Balabanov Vladimir, Haim Dan, Grossman Bernard, Mason William H., Watson Layne T., Haftka Raphael T.
Venue:  (1997)

The presence of numerical noise in engineering design optimization problems inhibits the use of many gradient-based optimization methods. This numerical noise may result in the inaccurate calculation of gradients which in turn slows or prevents convergence during optimization, or it may promote convergence to spurious local optima. The problems created by numerical noise are particularly acute in aircraft design applications where a single aerodynamic or structural analysis of a realistic aircraft configuration may require tens of CPU hours on a supercomputer. The computational expenses of the analyses coupled with the convergence difficulties created by numerical noise are significant obstacles to performing aircraft multidisciplinary design optimization. To address these issues, a procedure has been developed to create noise-free algebraic models of subsonic and supersonic aerodynamic performance qualities for use in the optimization of high-speed civil transport (HSCT) aircraft configurations. This procedure employs methods from statistical design of experiments theory and response surface modeling to create the noise-free algebraic models. Results from a sample HSCT design problem involving ten variables are presented to demonstrate the utility of this method.
A Distributed Kernel for Reliable Group Communication
Authors: Samuel T. Chanson, Ravindran K.
Venue:  (1986)

Multicasting provides a convenient and efficient way to perform one-to-many process communication. This paper presents a kernel model which supports reliable group communication in a distributed computing environment. We introduce new semantic tools which capture the nondeterminism of the underlying low level events concisely and describe a process alias-based structuring technique for the kernel to handle the reliability problems that may arise during group communication. The scheme works by maintaining a close association between group messages and their corresponding reply messages. We also introduce a dynamic binding scheme which maps group id''s to multicast addresses. The scheme allows the detection and subsequent recovery from inconsistencies in the binding information. Sample programs illustrating how the semantic tools may be used are also included.
A semi-universal e-commerce agent: domain-dependant information gathering
Authors: Aleksander Pivk, Matjaz Gams
Venue: Enterprise information systems IV (2003)

A universal e-commerce agent should provide commerce functions through the Internet by accessing arbitrary e-commerce sites and on this basis offer intelligent information services on its own. Our system ShinA (SHoppINg Assistant) is a semi-automatic e-commerce agent. It can enter an arbitrary e-commerce site by observing a human user performing the first query. By understanding key concepts of the first query, ShinA performs following queries by other users. In a consequence, a user enters ShinA by asking for a particular item, and ShinA provides all relevant e-commerce options from various providers. The major advantage of ShinA is a semi-automatic creation of a wrapper around a particular e-commerce site demanding minimal human interaction/corrections. ShinA is a successor of the EMA (EMployment Agent) prototype, which performs similar functions in job queries over the Internet.