ppxscal/embedding_network huggingface dataset:
Modelling of the effect of an impulse on a ground anchorage system
Authors: R. D. Neilson, A. Ivanovic, A. Starkey, A. A. Rodger
Venue: Proceedings of the eighth international conference on The application of artificial intelligence to civil and structural engineering computing (2001)

This paper presents the results of an investigation into the response of a ground anchorage system to an applied impulse as part of the ongoing development process for a ground anchorage integrity testing technique, GRANIT®. The paper describes the GRANIT® system and the numerical model used to simulate the anchorage in some detail and presents results from a number of simulations showing the ability of the model to accurately represent real anchorage systems. This is related to test results obtained from real anchorage systems. Good correlation is shown. Thereafter the effect of impact duration and shape on the response of an anchorage is examined with particular reference to the properties of the grout and the possibility of detection of voids or cavities in the grout. The final aim of the work is to indicate in advance the most suitable form of impulse load for a particular anchorage system dependent on the particular part of the anchorage system to be examined and some recommendations are given for the development of the system.
Investigating Advanced Transaction Models for Federated Database Systems.
Authors: K. Schwarz, C. Turker
Venue:  (1997)

Transaction management in federated database systems is a very difficult problem. In the literature, there are a lot of proposals for transaction models in federated database systems. However, all these models base on different assumptions or are restricted to certain application scenarios. In this paper, we analyze the underlying basic transaction types in order to have a foundation for comparing these models and for investigating their applicability in federated database system environments.
Towards a Theory of Recursive Structures
Authors: D. Harel
Venue:  (1994)

In computer science, one is interested mainly in finite objects. Insofar as infinite objects are of interest, they must be computable, i.e., recursive, thus admitting an effective finite representation. This leads to the notion of a recursive graph, or, more generally, a recursive structure or data base. In this paper we summarize our recent work on recursive structures and data bases, including (1) the high undecidability of many problems on recursive graphs, (ii) somewhat surprising ways of deducting results on the classification of NP optimization problems from results on the degree of undecidability of their infinitary analogues, and (iii) completeness results for query languages on recursive data bases. 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
Optimal Rectilinear Steiner Tree Routing in the Presence of Obstacles (supercedes CS-92-39, CS-93-15, and CS-93-19)
Authors: J. L. Ganley, J. P. Cohoon
Venue:  (1994)

This paper presents a new model for VLSI routing in the presence of obstacles, that transforms any routing instance from a geometric problem into a graph problem. It is the first model that allows computation of optimal obstacle-avoiding rectilinear Steiner trees in time corresponding to the instance size (the number of terminals and obstacle border segments) rather than the size of the routing area. For the most common multi-terminal critical nets---those with three or four terminals---we observe that optimal trees can be computed as efficiently as good heuristic trees, and present algorithms that do so. For nets with five or more terminals, we present algorithms that heuristically compute obstacle-avoiding Steiner trees. Analysis and experimental results demonstrate that the model and algorithms work well in both theory and practice. Also presented are several theoretical results: a derivation of the Steiner ratio for obstacle-avoiding rectilinear Steiner trees, and complexity results for two special cases of the problem.
Fitting Parameterized 3-D Models to Images
Authors: David G. Lowe
Venue:  (1989)

Model-based recognition and tracking from 2-D images depends upon the ability to solve for projection and model parameters that will best fit a 3-D model to matching image features. This paper extends current methods of parameter solving to handle objects with arbitrary curved surfaces and with any number of internal parameters representing articulations, variable dimensions, or surface deformations. Numerical stabilization methods are developed that take account of inherent inaccuracies in the image measurements and allow useful solutions to be determined even when there are fewer matches than unknown parameters. A standardized modeling language has been developed that can be used to define models and their internal parameters for efficient application to model-based vision. These new techniques allow model- based vision to be used for a much wider class of problems than was possible with earlier methods.
PARALLELIZING SUBGRAPH ISOMORPHISM REFINEMENT FOR CLASSIFICATION AND RETRIEVAL OF CONCEPTUAL STRUCTURES
Authors: James D. Roberts
Venue:  (1994)

Major applications of graph-based knowledge representations will require quick response times on extremely large knowledge bases. Although algorithmic developments have provided tremendous improvements in speed, we believe implementation on parallel processors will be needed to meet long-term needs. This paper presents a new parallelization of a subgraph isomorphism refinement algorithm for performing projection tests and retrieving conceptual structures. The improved algorithm is faster, requires fewer processors, and is compatible with recent relation-based representations of conceptual structures. The new parallelization takes advantage of the features of contemporary data-parallel parallel machines by exploiting bit-parallelism in wide data words. Processing numerous graphs on a single parallel array, it combines the strengths of prior parallel subgraph isomorphism implementations with multi-level indexed search. It incorporates lattice codes of the concept-type hierarchy to avoid a bottleneck in our prior parallelization and forms all node candidate binding lists in parallel. Simulation results of the behavior of the refinement algorithm with parameterized synthetic data sets are presented as are implications for hardware tailored to processing conceptual structures. 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
Improved Circuits and Formulae for Multiple Addition, Multiplication and Symmetric Boolean Functions
Authors: M. S. Paterson, U. Zwick
Venue:  (1990)

Circuits and formulae over several bases, with improved depth and size respectively, are given for the carry save addition of n binary numbers (i.e., obtaining two numbers whose sum is equal to the sum of the n numbers). As a consequence improved circuits and formulae for multiple addition, multiplication and for most symmetric Boolean functions are obtained.
Fault Coverage Evaluation of Protocol Test Sequences
Authors: Jinsong Zhu, Samuel T. Chanson
Venue:  (1993)

In this paper, we investigate the quality of a given protocol test sequence in detecting faulty implementations of the specification. The underlying model is a deterministic finite state machine (FSM). The basic idea is to construct all FSMs having n + i states (where n is the number of states in the specification and i a small integer) that will accept the test sequence but do not conform to the specification. It differs from the conventional simulation method in that it is not necessary to consider various forms of fault combinations and is guaranteed to identify any faulty machines. Preprocessing and backjumping techniques are used to reduce the computational complexity. We have constructed a tool based on the model and used it in assessing several UIO-based optimization techniques. We observed that the use of multiple UIO sequences and overlaps can sometimes weaken the fault coverage of the test sequence. The choice of the transfer sequences and order of the test subsequences during optimization may also affect fault coverage. Other observations and analysis on the properties of test sequences are also made.
DEBUGGING PARALLEL PROGRAMS BY TRACE ANALYSIS (M.S. Thesis)
Authors: Jian Wang
Venue:  (1990)

One of the fundamental problems encountered when debugging a parallel program is determining the race conditions in the program. A race condition may exist when two or more tasks access shared data in an unspecified order and at least one of them is executing a write operation. This paper discusses this problem and presents a tool for automatically detecting race conditions in parallel programs by analyzing program traces. In a parallel system, events can occur concurrently. However, programmers are often forced to rely on misleading sequential traces for information about their program''s behavior. We view a program execution as a partial ordering of events, and define which executions are consistent with a given trace. Although it is generally not possible to determine which of the executions occurred, we define the notion of ``safe orderings'''' which are guaranteed to occur in every execution that is consistent with the trace. We present a series of algorithms which extract many of the ``safe orderings'''' from a sequential trace with anonymous semaphore-style synchronization. The initialization algorithm starts from a sequential trace and creates a partially ordered canonical execution. The rewinding algorithm strips away the ordering relationships particular to the canonical execution, so that the resulting partial order is safe. The expanding algorithm increases the amount of ordering information while maintaining a safe partial order. An algorithm is also presented to detect critical regions, to distinguish unordered sequential events from concurrent events. We have focused on event style communication and counting semaphore models because they are one of the most frequently used parallel models, especially in various parallel Fortran versions. The ideas and the algorithms should be applicable to other parallel systems. A trace analyzer has been implemented, and some experiments have been performed. The current implementation is used to analyze traces generated by IBM Parallel Fortran. The trace analyzer can report various data race conditions in parallel programs by finding unordered/concurrent events and variable access conflicts.
Semantics of Reactive Components in Event-Driven Workflow Execution
Authors: Dimitrios Tombros, Andreas Geppert, Klaus R. Dittrich
Venue:  (1996)

The exact semantics of workflows and involved processing entities is an open yet urgent problem. This paper considers the semantics and correctness of event-driven workflow execution. The basis for the formalization in our approach is provided by an event history which records all events that have occurred during the execution of workflows. Workflows are executed by reactive components which operate on top of that history. Based on the history it is possible to determine the semantics of these reactive components (and consequently, the semantics of workflows) as well as to check whether their observable behavior is correct.
Intrusion detection and response for real-time distributed naval systems
Authors: B. L. Chappell, G. A. Fink, D. T. Marlow, K. F. O'Donoghue
Venue: Real-time system security (2003)

Information security in naval environments is becoming increasingly important with the move towards distributed engineering and computing, increased automation, and systems based upon non-developmental items (NDI). Naval applications have a broad range of communication timing requirements, from tens of seconds to sub-seconds For example, the communication between geographically dispersed operational sites may require responses in the seconds or tens of seconds range, while the communication between applications in a shipboard combat system that are responsible for targeting weapons have much more constrained timing requirements. Additionally, there are mission critical applications that have hard real-time requirements in which the reception of data outside of specific timing limits results in system failure, as well as mission critical applications with near real-time requirements that can tolerate a wider boundary of communication response times. The integration of information securivy services in such an environment invariably conflicts with the timing requirements of these applications. However, security services are arguably needed most in environments with the tightest communication requirements (e.g., while engaging hostile targets). NSWC-DD has begun evaluating the applicability of Intrusion Detection Systems (IDS) in naval environments. This paper describes current security architectures of naval platforms, potential future architectures, and desirable features of an IDS that may be integrated into these architectures.
A Taxonomy of Fairness and Temporal Logic Problems for Petri Nets
Authors: Rodney R. Howell, Louis E. Rosier, Hsu Yen
Venue:  (1988)

In this paper, we define a temporal logic for reasoning about Petri nets. We show the model checking problem for this logic to be PTIME equivalent to the Petri net reachability problem. Using this logic and two refinements, we show the fair nontermination problem to be PTIME equivalent to reachability for several definitions of fairness. For other versions of fairness, this problem is shown to be either PTIME equivalent to the boundedness problem or highly undecidable. In all, 24 versions of fairness are examined.
Performance Comparison of Three Parallel Implementations of a SchwarzSplitting Algorithm
Authors: Jim Gamble, Calvin J. Ribbens
Venue:  (1989)

We describe three implementations of a Schwarz splitting algorithm for the numerical solution of two dimensional, second-order, linear elliptical partial differential equations. One implementation makes use of the SCHEDULE package. A second uses the language extensions available in SEQUENT Fortran for creating and controlling parallel processes. The third implementation is a hybrid of the first two -- using explicit (non-portable) calls to create a control parallel processes, but using data structures and overhead similar to the implementation that uses SCHEDULE. We report from several experiments with typical test problems on a Sequent Symmetry S81 shared-memory multiprocessor. We measure the overhead involved in using SCHEDULE, and discuss advantages and disadvantages of this approach.
The impact of missing data on data mining
Authors: Marvin L. Brown, John F. Kros
Venue: Data mining: opportunities and challenges (2003)

Data mining is based upon searching the concatenation of multiple databases that usually contain some amount of missing data along with a variable percentage of inaccurate data, pollution, outliers, and noise. The actual data-mining process deals significantly with prediction, estimation, classification, pattern recognition, and the development of association rules. Therefore, the significance of the analysis depends heavily on the accuracy of the database and on the chosen sample data to be used for model training and testing. The issue of missing data must be addressed since ignoring this problem can introduce bias into the models being evaluated and lead to inaccurate data mining conclusions.
Isoperimetric Number of the Cartesian Product of Graphs and Paths
Authors: M. C Azizoglu, Omer Egecioglu
Venue:  (1998)

We prove that the isoperimetric number of P_k x G_k, the Cartesian product of the path P_k and a connected graph with k vertices, is equal to the isoperimetric number of P_k itself. At the same time we construct an infinite family of graphs that shows that this is not true for P_k x G where G has more than k vertices, even if G is a tree.
A Framework for Interoperability Testing of Network Protocols
Authors: Jadranka Alilovic-Curgus, Son T. Vuong
Venue:  (1993)

In this report, we extend the testing theory based on formal specifications by formalizing testing for interoperability with a new relation {\em intop}. Intuitively, $P$ $intop_{S}$ $ Q$ if, for every event offered by either $P$ or $Q$, the concurrent execution of $P$ and $Q$ will be able to proceed with the traces in $ S$, where $S$ is their (common) specification. This theory is applicable to formal description methods that allow a semantic interpretation of specifications in terms of labelled transition systems. Existing notions of implementation preorders and equivalences in protocol testing theory are placed in this framework and their discriminating power for identifying processes which will interoperate is examined. As an example, a subset of the ST-II protocol is formally specified and its possible implementations are shown to interoperate if each implementation satisfies the $ intop$ relation with respect to $S$, the specification of the ST-II protocol (subset).
Ore Size Distribution Measurement From 2-D Monochrome Images - Part I.
Authors: Anthony Zaknich
Venue:  (1991)

Abstract unavailable.
GROUP MEMBERSHIP IN THE EPIDEMIC STYLE
Authors: Richard A. Golding, Kim Taylor
Venue:  (1992)

Existing group membership mechanisms provide consistent views of membership changes. However, they require heavyweight synchronous multicast protocols. We present a new lightweight group membership mechanism that allows temporary inconsistencies in membership views. This mechanism uses *epidemic communication* techniques to ensure that all group members eventually converge to a consistent view of membership. Members can join or leave groups, and we show that the mechanism is resilient to k >= n - 2 members failing by crashing, where n is the number of members in the group. (supersedes UCSC-CRL-91-32)
Proxy Caching with Hash Functions
Authors: Florin Baboescu
Venue:  (2001)

Internet traffic doubles every three months, with web traffic accounting for more than 75% of the total traffic between major ISP providers. Web caching at proxies can reduce this traffic as well as web user latencies. One way to increase the hit rate of caches is to have caches cooperate using the Internet Cache Protocol or using hash functions. This paper provides an experimental and theoretical analysis of two well known hash based caching schemes. Our paper also proposes a new allocation scheme which improves the performance of one of the analyzed techniques. It reduces the standard deviation of the URLs distribution on caches by a factor greater than two without any increase on the scheme complexity.
Infinite Cyclic Impartial Games
Authors: A. S. Fraenkel, O. Rahat
Venue:  (1998)

We define the family of locally path-bounded digraphs, which is a class of infinite digraphs, and show that on this class it is relatively easy to compute an optimal strategy (winning or nonlosing); and realize a win, when possible, in a finite number of moves. This is done by proving that the Generalized Sprague-Grundy function exists uniquely and has finite values on this class.
Mathematical Chats Between Two Physicists
Authors: Aviezri S. Fraenkel
Venue:  (2000)

A family of two-player games on cellular automata is suggested. Its winning strategy, which depends on certain homomorphisms in vector spaces over GF(2), is sketched briefly. The strategy subsumes and unifies that of games which appeared previously in the literature.
The Composability of ASTRAL Realtime Specifications
Authors: Alberto Coen-Porisini, Richard A. Kemmerer
Venue:  (1993)

ASTRAL is a formal specification language for realtime systems. It is intended to support formal software development, and therefore has been formally defined. In ASTRAL a realtime system is modeled by a collection of state machine specifications and a single global specification. This paper focuses on extending the ASTRAL methodology to allow the composition of ASTRAL system specifications into specifications of larger and more complex systems. The ASTRAL language includes structuring mechanisms that allow one to build modularized specifications of complex systems with layering. In this paper we concentrate on how to combine these complex system specifications into specifications for even more complex realtime systems. This is accomplished by adding a COMPOSE section to the language that provides the needed information to combine two or more ASTRAL specifications into a single new one. In this paper we also introduce the necessary proof obligations to assure that the assumptions of each of the components of the larger system are satisfied by the other components of the system, which replace the previous external environment. We also discuss how some exported transitions become internal transitions of the new system. A telephony example with local central controls that interface to long distance units is used to motivate the extensions.
Forward Dynamics, Elimination Methods, and Formulation Stiffness in Robot Simulation
Authors: Dinesh P Uri Ascher, Cloutier Benoit
Venue:  (1995)

The numerical simulation problem of tree-structured multibody systems, such as robot manipulators, is usually treated as two separate problems: (i) the forward dynamics problem for computing system accelerations, and (ii) the numerical integration problem for advancing the state in time. The interaction of these two problems can be important and has led to new conclusions about the overall efficiency of multibody simulation algorithms [ClPaAs95]. In particular, the fastest forward dynamics methods are not necessarily the most numerically stable, and in ill-conditioned cases may slow down popular adaptive step-size integration methods. This phenomenon is called "formulation stiffness". In this paper, we first unify the derivation of both the composite rigid body method [WalkerOrin82] and the articulated-body method [Featherstone83,Featherstone87] as two elimination methods to solve the same linear system, with the articulated body method taking advantage of sparsity. Then the numerical instability phenomenon for the composite rigid body method is explained as a cancellation error that can be avoided, or at least minimized, when using an appropriate version of the articulated body method. Specifically, we show that the articulated-body method is better suited to deal with certain types of ill-conditioning than the composite rigid body method. The unified derivation also clarifies the underlying linear algebra of forward dynamics algorithms and is therefore of interest in its own accord.
FACE: A Flexible Approach for Constraint Enforcement and Compensation of Constraint
Authors: M. Spiliopoulou, S. Conrad
Venue:  (1997)

The autonomy of the particpants in a database federation makes the maintenance of consistency on the shared data a hard problem. A constraint mechanism at the federation level is often proposed as an elegant and effective solution. The introduction of active components is a powerful and natural way to enforce constraints over a federation, but is often not applicable due to the autonomy of the participants. We propose a model which supports constraint enforcement by a suite of autonomy-preserving mechanisms. Those mechanisms exploit the functionality of triggers and active components, if provided by the participants. For participants without such functionality, violations are detected by transaction supervision or by querying dubious data. A compensator module undertakes the re-establishment of consistency. Inconsistencies that cannot be resolved due to the autonomy of the participants are hidden from the federation users by a view mechanism.