ppxscal/embedding_network huggingface dataset:
ESTIMATION OF DISTRIBUTED PARAMETERS BY MULTIRESOLUTION OPTIMIZATION (Ph.D. Thesis)
Authors: Koji Amakawa
Venue:  (1994)

This dissertation proposes, develops and evaluates multiresolution optimization methods for estimation of distributed parameters of mathematical models. The methods are based on the assumption that the distributed parameters are continuous almost everywhere in the defined field. The main idea in employing multiresolution optimization is to give priority to large-scale characteristics of the parameter distribution over smaller-scale ones in the estimation process. This allows the overall structure of the distribution to be found more quickly, which results in rapid approach of the estimation to the true distribution. This in turn allows more reliable search for the details. The multiresolution optimization method consists of a local search method and a multiresolution scheme that controls the resolution of the search. This dissertation employs the conjugate gradient method as a local search method, and the discrete Fourier transform and the Haar wavelet transform as a multiresolution scheme. Since the coefficients of these transforms are inherently sorted in frequency or scale, multiresolution estimation can be realized by estimating the transform coefficients with some controlled weights and inversely transforming the coefficients back to the parameter distribution. Two methods of controlling the resolution are devised. One is the "step scheme" in which the threshold frequency for a low-pass filter steps up every time the search converges. The other method is the "weight scheme" in which fixed weights are assigned so that the coefficients of low frequencies get larger weights than the coefficients of higher frequencies. This dissertation gives a proof that estimating the transform coefficients in either scheme is equivalent to directly estimating the desired parameter distribution by using the gradient that is filtered by the transform. In other words, we can realize a multiresolution optimization by simply filtering the gradient in a multiresolution manner to control the resolution of the search direction. The developed methods are evaluated in simulation of the so-called electrical impedance tomography, which is one of many potential applications. It is shown that the multiresolution optimization yields better estimates more rapidly than the conventional single-resolution method.
Information management in a decision support system for pavement management
Authors: A. P. Chassiakos, D. D. Theodorakopoulos, I. D. Manariotis
Venue: Proceedings of the eighth international conference on The application of artificial intelligence to civil and structural engineering computing (2001)

The aim of this paper is to present the structure and the information management process of a decision support system for highway pavement management. The system consists of a database, a user interface module, and analysis tools for pavement condition prediction, allocation of maintenance funds according to needs and priorities, and management of maintenance projects. Data used by the system refer to road network characteristics, existing pavement distresses, alternative maintenance actions, and management objectives. The system provides output in tabular and graphical form (through GIS application) regarding pavement condition over time, proposed maintenance activities and cost distribution, project organisation and management.
An Implementation of a Parallel Object Oriented Database System
Authors: Russell F. Haddleton
Venue:  (1995)

In the following document we describe the current implementation of ADAMS, a parallel object oriented database system developed at the University of Virginia. The parallel data structures employed by ADAMS are discussed, as is the client/server architecture. We list a number of sources of parallel speed-up found in typical ADAMS programs, and explain how these opportunities are exploited. Several potential future research projects related to this work are given.
Dense Edge-Disjoint Embedding of Complete Binary Trees in Interconnection Networks
Authors: S. Ravindran, A. M. Gibbons, M. S. Paterson
Venue:  (1995)

We describe dense edge-disjoint embeddings of the complete binary tree with n leaves in the following n-node communication networks: the hypercube, the de Bruijn and shuffle-exchange networks and the two-dimensional mesh. For the mesh and the shuffle-exchange graphs each edge is regarded as two parallel (or anti-parallel) edges. The embeddings have the following properties: paths of the tree are mapped onto edge-disjoint paths of the host graph and at most two tree nodes (just one of which is a leaf) are mapped onto each host node. We prove that the maximum distance from a leaf to the root of the tree is asymptotically as short as possible in all host graphs except in the case of the shuffle-exchange, in which case we conjecture that it is as short as possible. The embeddings facilitate efficient implementation of many P-RAM algorithms on these networks.
ELIMINATION OF UNDETECTABLE SHORTS DURING CHANNEL ROUTING
Authors: Richard McGowen, F. J Ferguson
Venue:  (1993)

In this paper we present a procedure for reducing the probability of undetectable shorts occurring in routing channels. This procedure is implemented by modifying a channel router to predict many of the shorts that are undetectable and place the associated signal wires in non-adjacent tracks. For the designs we routed, we found that the probability of an undetectable non-feedback short between horizontal lines in the routing channels was reduced by 32.4% with no increase in the number of routing tracks required and little increase in routing computation cost.
Certificate Revocation and Certificate Update
Authors: M. Naor, K. Nissim
Venue:  (1999)

We present a solution for the problem of certificate revocation. This solution represents Certificate Revocation Lists by authenticated dictionaries that support (i) efficient verification whether a certificate is in the list or not, and (ii) efficient updates (adding/removing certificates from the list). The suggested solution gains in scalability, communication costs, robustness to parameter changes and update rate. Comparisons to the following solutions (and variants) are included: `traditional'' CRLs (Certificate Revocation Lists), Micali''s Certificate Revocation System (CRS) and Kocher''s Certificate Revocation Trees (CRT). We also consider a scenario in which certificates are not revoked, but frequently issued for short-term periods. Based on the authenticated dictionary scheme, a certificate update scheme is presented in which all certificates are updated by a common message. The suggested solutions for certificate revocation and certificate update problems is better than current solutions with respect to communication costs, update rate, and robustness to changes in parameters and is compatible e.g. with X.500 certificates.
In Search of an Optimal Machine Architecture for BCPL
Authors: R. Agarwal, Samuel T. Chanson
Venue:  (1979)

This paper investigates the problem of generating optimal space-efficient code for the language BCPL. Designing such a code was seen to be a two-phase process. The first phase was to describe an internal representation scheme for BCPL programs which preserved those program features which are salient to translation and at the same time minimize the number of instructions generated. The second phase consisted of the realization of the internal representation as an actual machine taking into account the usage frequencies of instructions and other real world constraints such as word size and addressing space. The \underline{i}ntermediate \underline{c}od\underline{e}, called ICE and an encoding scheme (known as ESO, standing for \underline{e}ncoding \underline{s}cheme \underline{0}) are described. ICE/ESO is seen to reduce code size by an average of about 32% compared to BCODE which is a realization of OCODE, the intermediate language currently used in BCPL program translation.
ACCESSING REPLICATED DATA IN A LARGE-SCALED DISTRIBUTEDSYSTEM
Authors: Richard Golding, Darrell D. E. Long
Venue:  (1991)

Replicating a data object improves the availability of the data, and can improve access latency by locating copies of the object near to their use. When accessing replicated objects across an internetwork, the time to access different replicas is non-uniform. Further, the probability that a particular replica is inaccessible is much higher in an internetwork than in a local-area network (LAN) because of partitions and the many intermediate hosts and networks that can fail. We report three replica-accessing algorithms which can be tuned to minimize either access latency or the number of messages sent. These algorithms assume only an unreliable datagram mechanism for communicating with replicas. Our work extends previous investigations into the performance of replication algorithms by assuming unreliable communication. We have investigated the performance of these algorithms by measuring the communication behavior of the Internet, and by building discrete-event simulations based on our measurements. We find that almost all message failues are either transient or due to long-term host failure, so that retrying messages a few times adds only a small amount to the overall message traffic while improving both access latency as long as the probability of message failure is small. Moreover, the algorithms which retry messages on failure provide significantly improved availability over those which do not.
Experiences with Legion on the Centurion Cluster
Authors: Greg Lindahl, Steve J. Chapin, Norman Beekwilder, Andrew Grimshaw
Venue:  (1998)

The Legion Project spends most of its time building metacomputing environments and applications, but we are also actively building a clustered system, which we have named Centurion. Centurion is currently a cluster of 64 Alpha PCs, networked with low-latency gigabit networking hardware from Myricom, joined by a dozen x86-architecture PCs. We plan on doubling the size of the cluster in the near future. This shared-nothing, heterogeneous environment is an ideal fit for the Legion metacomputing system, which provides services such as naming, scheduling, heterogeneous communications, and parallel I/O. Centurion is roughly the size of "small" HPC systems in use today at supercomputing centers, giving us the opportunity to compare price and performance with traditional systems, and investigate the hardware and software challenges of building large clusters with commodity hardware. This paper will cover our experiences with Centurion and Legion. We begin with an overview of the Legion metacomputing system. We will then discuss the costs and hidden costs of assembling a cluster. We then describe the performance of Centurion, using microbenchmarks of the communications system, standard parallel application benchmarks, and user applications. User applications running on the system come from a variety of scientific disciplines, and range from traditional MPI codes taken straight from supercomputers to more novel applications using "bag of tasks" and macro-dataflow formalisms. Within this range of applications, we will discuss our successes and failures with hiding network latency, load balancing, and most importantly, usability of the system by researchers without extensive training in parallel computing.
Automated Delegation is a Viable Alternative to Multiple Inheritance in Class Based Languages
Authors: John Viega, Bill Tutt, Reimer Behrends
Venue:  (1998)

Multiple inheritance is still a controversial feature in traditional object-oriented languages, as evidenced by its omission from such notable languages as Modula-3, Objective C and Java . Nonetheless, users of such languages often complain about having to work around the absence of multiple inheritance. Automating delegation, in combination with a multiple subtyping mechanism, provides many of the same benefits as multiple inheritance, yet sidesteps most of the associated problems. This simple feature could satisfy both the designers and the users of class based object oriented languages. In this paper, we discuss why automated delegation is desirable. We also present Jamie, a freeware preprocessor-based extension to Java that offers such an alternative.
Das Transputer-Lehrsystem
Authors: Jurgen W. Meyer, Volkhard Klinger
Venue:  (1992)

Fur die Ausbildung im Bereich der Parallelverarbeitung wurde das Transputer-Lehrsystem konzipiert. Seine Verwendbarkeit reicht vom einfachen Einstieg in die Parallelverarbeitung bis hin zu anspruchsvollen Aufgaben. In diesem Artikel sollen die Konzepte sowie die Charakteristika dargestellt werden.
Parallel Construction of Subdivision Hierarchies
Authors: Norm Dadoun, David G. Kirkpatrick
Venue:  (1987)

A direct, simple and general parallel algorithm is described for the preprocessing of a planar subdivision for fast (sequential) search. In essence, the hierarchical subdivision search structure described by Kirkpatrick [K] is constructed in parallel. The method relies on an efficient parallel algorithm for constructing large independent sets in planar graphs. This is accomplished by a simple reduction to the same problem for lists. Applications to the manipulation of convex polyhedra are described including an \( O(\log^{2}n \log^{*}n) \) parallel time algorithm for constructing the convex hull of $n$ points in $R^{3}$ and an \( O( \log n \log^{*}n) \) parallel time algorithm for detecting the separation of convex polyhedra.
An Optimal Boundary to Quadtree Conversion Algorithm
Authors: Mark Lattanzi, Clifford A. Shaffer
Venue:  (1989)

An algorithm is presented for converting a boundary representation for an image to its region quad-tree representation. Our algorithm is designed for operation on the linear quadtree representation, although it can easily be modified for the traditional pointer-based quadtree representation. The algorithm is a two phase process that first creates linear quadtree node records for each of the border pixels. This list of pixels is then sorted by locational code. The second processing phase fills in the nodes interior to the polygons by simulating a traversal of the corresponding pointer-based quadtree. Three previous algorithms [Same80, Mark85a, Atki86] have described similar conversion routines requiring time complexity of O(n.B)for at least one of the two phases, where B is the number of boundary pixels and n is the depth of the final tree for a 2" x 2" image. A fourth algorithm [Webb84] can perform the border construction of this conversion in time O(n+B) with the restriction that the polygon must be positioned at constrained locations in the image space. Our algorithm requires time O(n + B) for the second phase, which is optimal. The first phase can be performed using the algorithm of [Webb84] for total conversion time of O(n + B) with constrained location, or in time O(B log B) using a simple sort to order the border pixels with no restriction in polygon location.
Market-Based Workflow Management
Authors: Andreas Geppert, Markus Kradolfer, Dimitrios Tombros
Venue:  (1997)

This paper presents market-based workflow management, a novel approach to workflow specification and execution which regards activities contained in a workflow as goods traded on an electronic market. Information about expected cost and execution time is considered for activity specifications, and is used at runtime to execute workflows such that actual cost and execution times are balanced and optimized. To that end, task assignment uses a bidding protocol, in which each eligible processing entity specifies at which price and in which time interval he/she can execute the activity. The winner of a specific bidding process is requested execute the activity, and earns the amount specified in the corresponding bid. Market-based workflow management thus not only allows to optimize workflow executions with respect to execution time and overall cost; but the trading of activities represents an incentive for processing entities to engage in a workflow.
ACT++ 2.0: A Class Library for Concurrent Programming in C++ Using Actors
Authors: Dennis G. Kafura, Manibrata Mukherji, Gregory R. Lavender
Venue:  (1992)

ACT++ 2.0 is the most recent version of a class library for concurrent programming in C++. The underlying model of concurrent computation is the Actor model. Programs in ACT++ consist of a collection of active objects called actors. Actors execute concurrently and cooperate by sending request and reply messages. An agent, termed the behavior of an actor, is responsible for processing a single request message and for specifying a replacement behavior which processes the next available request message. One of the salient features of ACT++ is its ability to handle the Inheritance Anomaly---the interference between the inheritance mechanism of object-oriented languages and the specification of synchronization constraints in the methods of a class---using the notion of behavior sets. ACT++ has been implemented on the Sequent Symmetry multiprocessor using the PRESTO threads package.
The Interpretation of States: a New Foundation for Computation?
Authors: W. M. Beynon, S. B. Russ
Venue:  (1992)

Computation is a central concept in computer science. The mathematical theory of computation, with its historical origins that predate the computer, has been most influential in the development of programming languages, tools and methodologies. The study of psychological aspects of computation is by comparison a new concern that has developed largely as a post hoc investigation of contemporary methods of programming; it has yet to make a serious impact upon computer science theory. In this paper , we shall argue that concerns about perception and interpretation that are significant in psychology should be a primary source of insight into the new models of computation that will shape future developments in computer programming. To this end, we reconsider fundamental issues concerning the nature of computation and its relationship to mathematics and cognition. In particular, we shall explain how computation has to be understood with reference to * physical processes that are perceived to undergo changes of state * conceptual methods for interpreting state changes in computational terms. Brief references to our work on agent-oriented programming using definition-based representations of state will be used to explain our thesis.
Lower Bound on the Number of Rounds for Consensus with Dependent Process Failures
Authors: Flavio Junqueira, Keith Marzullo
Venue:  (2003)

In this paper, we generalize the lower bound on the number of rounds for Consensus algorithms assuming that processes fail dependently. This lower bound is general in the sense that it is independent of the failure assumptions for processes. In order to instantiate it, one needs to provide a necessary condition on process replication for a given failure model in terms of our abstractions to represent dependent failures. A surprising corollary of our generalization is that the lower bound on the number of rounds, in general, differs between the crash and the arbitrary failure models.
A Fast Multi-Scale Method for Drawing Large Graphs
Authors: D. Harel, Y. Koren
Venue:  (1999)

We present a multi-scale layout algorithm for the aesthetic drawing of undirected graphs with straight-line edges. The algorithm is extremely fast, and is capable of drawing graphs of substantially larger size than any other algorithm we are aware of. For example, the algorithm achieves optimal drawings of 1000 vertex graphs in less than 5 seconds. The paper contains several graphs with over 3000 nodes. The proposed algorithm embodies a new multi-scale scheme for drawing graphs, which was motivated by the recently published multi-scale algorithm of Hadany and Harel. It can significantly improve the speed of essentially any force-directed method (regardless of that method''s ability of drawing weighted graphs or the continuity of its cost-function). In passing, we also discuss simple modifications of the known Kamada and Kawai force-directed method, which greatly improve its ability to deal with large graphs.
Multi-level software validation for NOC
Authors: Sungjoo Yoo, Gabriela Nicolescu, Iuliana Bacivarov, Wassim Youssef, Aimen Bouchhima, Ahmed A. Jerraya
Venue: Networks on chip (2003)

This chapter presents a problem in conventional methods of validating software design for NoC: software validation at different abstraction levels. As a solution to resolve the problem, a method of multi-level software validation is explained.
Managing Contention and Timing Constraints in a Real-Time Database System
Authors: Matthew R. Lehr, Sang H. Son
Venue:  (1994)

This technical report discusses how current real-time technology has been applied to a database management system to support firm real-time transactions. The report reviews priority-based CPU- and resource scheduling concepts and shows how they are used to avoid the problem of priority inversion in transaction service order, transaction progress, and memory allocation. Next, the appropriateness of optimistic concurrency control to real-time data management is examined, and the implementation of previously proposed methods WAIT-X(S) and Precise Serialization is detailed. Finally, the enforcement of firm deadlines using asynchronous aborts is discussed.
ON THE WORST-CASE ANALYSIS OF TEMPORAL-DIFFERENCE LEARNING ALGORITHMS
Authors: Robert E. Schapire, Manfred K. Warmuth
Venue:  (1994)

We study the worst-case behavior of a family of learning algorithms based on Sutton''s method of temporal differences. In our on-line learning framework, learning takes place in a sequence of trials, and the goal of the learning algorithm is to estimate a discounted sum of all the reinforcements that will be received in the future. In this setting, we are able to prove general upper bounds on the performance of a slightly modified version of Sutton''s so-called TD(lambda) algorithm. These bounds are stated in terms of the performance of the best linear predictor on the given training sequence, and are proved without making any statistical assumptions of any kind about the process producing the learner''s observed training sequence. We also prove lower bounds on the performance of any algorithm for this learning problem, and give a similar analysis of the closely related problem of learning to predict in a model in which the learner must produce predictions for a whole batch of observations before receiving reinforcement.
A microstructural computation simulation model of loess soils
Authors: S. C. Dibben, I. F. Jefferson, I. J. Smalley
Venue: Proceedings of the eighth international conference on The application of artificial intelligence to civil and structural engineering computing (2001)

A major geotechnical problem encountered with loess deposits is structural collapse upon saturation under load, a process known as hydrocollapse. To elucidate this problem at a microstructural level a computer simulation of the soil has been developed using Monte Carlo random number theory. This enables models to be produced encompassing a variety of microstructural fabrics observed with loess, from the initial formation to the development of a metastable structure and ultimately the hydrocollapsed structure. The influence of particle shape and size on the structure, and the void ratio, are analysed. A physical model has been created in parallel to the computer simulation in order to validate this work. The results from the two types of model correspond well, with void ratios of between 1.2 and 1.6 being obtained for the initial structure; 0.9 to 1.1 for the metastable structure; and 0.5 to 0.7 for the hydrocollapsed structure. The resulting reduction in volume, occurring suddenly, constitutes a serious geohazard.