ppxscal/embedding_network huggingface dataset:
Stochastic Navier-Stokes equations: Analysis of the noise to have a unique invariant measure
Authors: Benedetta Ferrario
Venue:  (1997)

The aim of the paper is to provide a complete analysis of sufficient conditions for the existence of a unique invariant measure for the 2D Navier--Stokes equations perturbed by a white noise term. An invariant measure is, roughly speaking, a ``statistical stationary solution'''' and is a good candidate to represent the asymptotic behavior of the system. If this invariant measure is unique, there are chances that the law of the process solution will converge to it. Therefore, when this holds true, this unique invariant measure describes the (statistical) equilibrium to which the system tends. In this paper we prove that a unique invariant measure exists and the convergence takes place when the 2D Navier-Stokes equations are perturbed by a time--white noise, not degenerate in space, but with no limitations on the way it affects the modes of the phase space. From the technical point of view, this means to check irreducible and strongly Feller properties; such properties characterize the asymptotic behavior of general semilinear stochastic evolution equations and moreover are sufficient conditions for the uniqueness of the invariant measure. In general, without constraints on the Reynolds number, the deterministic Navier-Stokes equations have many stationary solutions. No information about the long time behavior is directly related to them. But they can be understood as invariant measures for the Navier-Stokes equations without the noise. Hence, our result means that, when a sufficiently distributed random perturbation is added, just one invariant measure exists. The effect of the noise is to mix up the dynamics of the system, allowing a unique asymptotic behavior. EMAIL:: ian@microian.ian.pv.cnr.it 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
Efficient Protocols for Permutation Routing on All-Optical Multistage Interconnection Networks
Authors: Qian-Pin Gu, Shietung Peng
Venue: Proceedings of the Proceedings of the 2000 International Conference on Parallel Processing (2000)

To realize a routing request R on a WDM (wavelength division multiplexing) all-optical network, one needs to set up routing paths in the network for every input-output pair in R and to assign a wavelength to each path so that the paths with the same wavelength are edge-disjoint. The optical bandwidth of the WDM all-optical network is the number of wavelengths supported by each link of the network. If the number of wavelengths for realizing R is at most the bandwidth of the network then R can be routed in one round of routing. However, when the number of wavelengths needed is beyond the bandwidth, multiple rounds of routing are required. In this case, it is important to minimize the number of rounds of routing. We give two deterministic algorithms for permutation routings on the parallel computing systems connected by all-optical multistage inter-connection networks (MINs). F or the parallel computing systems with practical size, the first algorithm realizes any permutation in two rounds of routing. The second algorithm realizes any bit-permute-complement (BPC) permutation on the n-dimensional MINs in two rounds of routing.
Constructing Levels in Arrangements and Higher Order Voronoi Diagrams
Authors: K P Agarwal, de M Berg, Ji Matou{\v s}ek.,  r}{\''\i}, Otfried Schwarzkopf
Venue:  (1995)

We give simple randomized incremental algorithms for computing the ${\leq}k$-level in an arrangement of $n$ hyperplanes in two- and three-dimensional space. The expected running time of our algorithms is $O(nk+n\alpha(n)\log n)$ for the planar case, and $O(nk^2+n\log^3 n)$ for the three-dimensional case. Both bounds are optimal unless $k$ is very small. The algorithm generalizes to computing the ${\leq}k$-level in an arrangement of discs or $x$-monotone Jordan curves in the plane. Our approach can also be used to compute the $k$-level; this yields a randomized algorithm for computing the order-$k$ Voronoi diagram of $n$ points in the plane in expected time $O(k(n-k)\log n +n\log^3 n)$.
A Method for Studying Spatial Patterns: The Net-Function Interpolation
Authors: Jianguo Wu
Venue:  (1993)

Interpolation is essential to most studies of spatial patterns in ecology. However, there has been a lack of quantitative techniques for interpolation of spatial data. This paper introduces a new method for studying spatial patterns, the two-dimensional net-function interpolation. The method can be used to interpolate unmeasured sample locations based on known values at nearby grid points. Specific examples from ecological studies in the Inner Mongolia grassland, China are discussed to illustrate the use of the method. A brief comparison between the net-function interpolation and kriging is also made. The method may provide a useful tool assisting collection of field data of spatial patterning of physical and biological entities, and would allow ecologists to obtain vegetation, soil and other ecological maps based on field observations with greatly reduced effort and over relatively large extent. Beyond that, the net-function technique seems to have potential for other fields (e.g., mining, forestry, meteorology, and structural geology) in which spatial interpolation plays a crucial role. 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
Constant Ratio Approximations of Feedback Vertex Sets inWeighted Undirected Graphs
Authors: Vineet Bafna, Piotr Berman, Toshihiro Fujito
Venue:  (1996)

A feedback vertex set of a graph is a subset of vertices that contains at least one vertex from every cycle in the graph. We show that a feedback vertex set approximating a minimum one within a constant factor can be efficiently found in undirected graphs. In fact the derived approximation ratio matches the best constant ratio known today for the vertex cover problem, improving the previous best results for both weighted and unweighted cases. The existence of an approximation preserving reduction of the vertex cover problem to the feedback vertex set problem suggests that further improvement of the obtained ratio will require entirely new ideas. We extend our approach to handle graphs of bounded vertex degree, and show an improved performance ratio for this case. These approximation bounds are obtained by using a non--trivial generalization of the classical local ratio principle of Bar--Yehuda and Even.
Managing outage time of telecommunication services
Authors: H. Watanabe, H. Miyashita, H. Miyata, T. Abe
Venue: Proceedings of the IEEE Symposium on Computers and Communications (ISCC'95) (1995)

Customers of telecommunication services are strongly interested in the service outage time. In order to respond to these requirements, the following measures are now being investigated. The first is to keep the frequency of outages of which the duration time exceeds a certain length under a certain level, and the second is to inform the customers of the residual outages time when a service outage occurs. The evaluation and design method of the frequency of long outages has been developed in order to achieve the first objective. The prediction method of the residual outage time has also been developed for the second objective. Moreover, the software tool for assisting one to carry out those measures are also being developed. The outline of those evaluation and prediction methods and the software tool is described.
A Generic Arc Consistency Algorithm and Its Specializations
Authors: Pascal Van Hentenryck, Yves Deville, Choh Teng
Venue:  (1991)

Consistency techniques have been studied extensively in the past as a way of tackling constraint satisfaction problems (CSP). In particular, various arc-consistency algorithms have been proposed, originating from Waltz''s filtering algorithm and culminating in the optimal algorithm AC-4 of Mohr and Henderson. AC-4 runs in $O(ed^2)$ in the worst case where $e$ is the number of arcs (or constraints) and $d$ is the size of the largest domain. Being applicable to the whole class of (binary) CSP, these algorithms do not take into account the semantics of constraints. In this paper we present a new generic arc-consistency algorithm AC-5. The algorithm is parameterized on two specified procedures and can be instantiated to reduce to AC-3 and AC-4. More important, AC-5 can be instantiated to produce an $O(ed^2)$ algorithm for a number of important classes of constraints: functional, anti-functional, monotonic and their generalization to (functional, anti-functional, and monotonic) piecewise constraints. We also show that AC-5 has an important application in constraint logic programming over finite domains. The kernel of the constraint-solver for such a programming language is an arc-consistency algorithm for a set of basic constraints. We prove that AC-5, in conjuction with node consistency, provides a decision procedure for these constraints running in time $O(ed)$.
A Bayesian Framework for Model Based Tracking
Authors: Yuri Boykov, Daniel Huttenlocher
Venue:  (1999)

We present a Bayesian framework for tracking an object in a sequence of image frames. A maximum a posteriori (MAP) recognition method is used to detect the object in each image frame, and a Kalman filter is used to estimate the true location from these observed locations. There is a natural feedback loop between the recognition method and the Kalman filter. The recognition method requires a prior on object location which is provided by the Kalman filter, and the Kalman filter requires an observed location which is provided by the recognition method. This framework has two desirable properties. First, the threshold for recognition in each frame depends on the system noise of the Kalman filter. This allows the system to identify partially occluded or distorted objects as long as the predicted locations are accurate. But requires a very good match if there is uncertainty as to the object location. Second, the search area for the recognition method is adaptively pruned using the current level of noise in the system, yielding an efficient overall method. Promising experimental results are demonstrated.
Integrated E-Learning: Pedagogy, Technology and Organization
Authors: Wim Jochems, Jeroen van Merrienboer, Rob Koper
Venue:  (2003)

:This book recognizes that online and e-learning are no longer of exclusive concern of distance education and that they can no longer be considered in isolation from traditional education programs. The authors view e-learning as part of a continuum of learning environments  that include classroom teaching, self-study, on-the-job training and active practice of skills  and offer a framework and practical guidance for optimizing the use of each to achieve learning objectives. By offering a coherent approach to instructional design they show how e-learning can be designed to support other forms of learning, rather than being a matter of simply "digitizing" traditional materials. They propose the integration of pedagogical, technological and organizational factors. This is a hands-on book reflects the contributors' considerable teaching experience and demonstrates how to design, develop, implement and evaluate integrated courses. "Integrated E-Learning" is essential reading for anyone wanting to implement, design develop or deliver e-learning or training courses.
A Generic Distributed Broadcast Scheme in Ad Hoc Wireless Networks
Authors: Jie Wu, Fei Dai
Venue: Proceedings of the 23rd International Conference on Distributed Computing Systems (2003)

We propose a generic framework for distributed broadcastingin ad hoc wireless networks. The approach is basedon selecting a small subset of hosts (also called nodes) toform a forward node set to carry out a broadcast process.The status of each node, forwarding or non-forwarding, isdetermined either by itself (self-pruning) or by other nodes(neighbor-designating). Node status can be determinedat different snapshots of network state along time (calledviews) without causing problems in broadcast coverage. Asufficient condition, called coverage condition, is given fora node to take the non-forward status. Such a condition canbe easily checked locally around the node. Several existingbroadcast algorithms can be viewed as special cases of thegeneric framework with k-hop neighborhood information.A comprehensive comparison among existing algorithms isconducted. Simulation results show that new algorithms,which are more efficient than existing ones, can be derivedfrom the generic framework. This work is an extension toan early work in which only self-pruning methods are discussed[16].
CARRYING THE MASS FLUX TERMS EXACTLY IN THE FIRST AND SECOND MOMENT EQUATIONS OF COMPRESSIBLE TURBULENCE
Authors: J. R. Ristorcelli
Venue:  (1993)

In compressible turbulence models it is assumed that the Favre-mean velocities are suitable approximations to the Reynolds-mean velocities in order to close unknown terms. This neglects, in the mean momentum and energy equations, the contribution to the stress and work terms by the mean of the fluctuating Favre velocity, a quantity proportional to the turbulent mass flux. As the stress and work terms do not introduce any new unknown correlations requiring closure in either k-varepsilon or Reynolds stress closures and because the exact form of the terms can, with little additional work, be carried there is no need to make any modeling assumptions. In the Reynolds stress equations the viscous terms appear naturally in Reynolds variables while the problem is posed in Favre variables. In the process of splitting the viscous terms into the viscous transport terms, carried in Favre variables, and the dissipation terms, carried in Reynolds variables, important contributions from the mass flux appear. The accurate accounting of these terms is important for any consistent near wall modeling and the retention of the mass flux terms is important in complex compressible turbulent flows.
A Scalable and Small Forwarding Table for Fast IP Address Lookups
Authors: Sungkee Jean, Sang-Hung Chung, Jung-Wan Cho, Hyunsoo Yoon
Venue: Proceedings of the 2001 International Conference on Computer Networks and Mobile Computing (ICCNMC'01) (2001)

IP address lookup is an important design issue for the high performance Internet routers. The most important function of routers is to determine the output port of an incoming IP packet according to its destination address. In this paper, we propose a scalable and simple forwarding table structure for fast hardware-based IP address lookup which reduces memory requirements and memory access times. Proposed scheme requires maximum two memory access times in the worst case to finish an IP address lookup. And it consumes about 0.6 ¢ 1.1MBytes memory for large routing tables with 16,000 ¢ 43,000 routing prefixes whenany compression method is not used.
Studying the Evolution and Enhancement of Software Features
Authors: Idris His, Colin Potts
Venue: Proceedings of the International Conference on Software Maintenance (ICSM'00) (2000)

The evolution and enhancement of features during system evolution can have significant effects on its coherence as well as its internal architecture. Studying the evolution of system features and concepts across a product line from an external or problem domain perspective can inform the process of identifying and designing future features. We show how we derive three primary views, morphological, functional, and an object view, from the user-level structures and operations of a system, using a case study of Microsoft Word's evolution. We show how these views illustrate feature evolution over three versions of Word. Lastly, we discuss the lessons learned from our study of feature evolution.
EFFICIENT ACCESS TO KNOWLEDGE VIA FORWARD CHAINING TACTICS
Authors: Ze Chen
Venue:  (1995)

The goal of this work is to explore efficient ways to use knowledge in interactive development of formal arguments. The challenge in automatically applying knowledge from a large knowledge base is in defining useful and tractable approximations to the deductive closure of the knowledge base. For an approximation to be useful, it must be deep in some directions. For it to be tractable, it must not be deep in all directions. Further, it must be easy to control this directedness. Thus, we need to make selective inferences from a large knowledge base that are sensitive both to its internal structure and to the query under consideration. To do this, most interactive systems employ a combination of heuristics and explicit user commands. The interaction of these two is intricate: to efficiently give hints to a heuristic prover requires developing a model of reasoning that is both efficiently implementable and easy to understand and use, i.e., fast, having a concise command language and predictable results. Rule-based specifications of approximations is the starting point for the contribution of this thesis in solving the problem described above. In this thesis, we analyze the use of rule-based forward chaining inference procedures and develop several extensions to the basic approach. We propose a new language for forward chaining tactics that can be used to specify goal-directed inference from large knowledge bases. This provides a modular approach to programming the heuristics for theorem proving. The tactic language has clean theoretical properties that make it appropriate for automated analysis and optimization. From the software engineering perspective, this thesis contains an assessment of the new software engineering approach of the theorem prover Ontic: specifying high performance theorem provers in a bottom-up logic programming framework. This perspective provides a much needed link between the Ontic project and other established research paradigms. The analysis tools developed for evaluating the forward chaining approach to obvious reasoning should have broad applications in evaluating other semi-automated approaches and systems. We also develop a language for declarative specification of control for forward chaining reasoning that is analogous to the role of LCF tacticals for specifying control in refinement-style reasoning, as embodied in Nuprl. We arrived at promising conclusions about the potential for combining these two styles of tactic programming in such problems as the integration of decision procedures and rewriting into interactive theorem provers. 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 Distributed Solution for Resources Allocation to Overlapping Groups
Authors: Zixue Cheng, Yutaka Wada, Shoichi Noguchi, Yao Xue Zhang
Venue: Proceedings of the Seventh International Conference on Parallel and Distributed Systems (2000)

The distributed resource allocation problem is a well known fundamental problem in distributed systems. Many solutions which avoid the deadlock and starvation have been developed. With the progress of computer networks, however, distributed cooperative group activities in a network environment have been increasing, so that several groups may compete for some resources in the network environment and deadlock among groups and starvation of a group may happen. Since previous allocation models are mainly for representation of competition for resources among processes, they cannot reflect clearly the competition for resources among groups of processes. Moreover, though the previous solutions to the distributed resource allocation problem can avoid the deadlock and starvation, they cannot deal with the deadlock among groups and starvation of a group.In this paper, we present a new model which described explicitly the competition for resources among process groups which may share common processes, and a definition of ¿Distributed Allocation of Resources to process Group¿ (DARG) under the model. A solution to DARG is also proposed by extending an acyclic graph approach to the dining philosopher problem. Our solution allocates resources to groups of processes with deadlock among groups and starvation of a group never happening. In addition, our solution guarantees that more than one group work mutual exclusively, if a common process belongs to these groups.
A User''s Guide to PMT A computer System Performance Modeling Tool
Authors: Richard W. Conway
Venue:  (1984)

NOT SUPPLIED
Bi-Level Optimisation Using Genetic Algorithm
Authors: V. Oduguwa, R. Roy
Venue: Proceedings of the 2002 IEEE International Conference on Artificial Intelligence Systems (ICAIS'02) (2002)

In most real-life problems such as rolling system design decision-making can be hierarchical and the search space is unknown. Bilevel optimisation problem (BLP) is an operation research technique for solving real life hierarchical decision-making problems. There are a number of different algorithms developed based on classical optimisation methods to solve different classes of the BLP problems where the search space is known. There also exist a number of problems in the BLP which current algorithms are not sufficiently robust to solve. In this paper, Bi-level Genetic Algorithm (BiGA) is a new proposed to solve different classes of the BLP problems within a single framework. BiGA is an elitist optimisation algorithm developed to encourage limited asymmetric cooperation between the two players. The performance of the algorithm is illustrated using test functions. The results suggest that BiGA algorithm is robust to solve different classes of the BLP problems and demonstrates potential for real life problems.
Data Modeler's Workbench: Tools and Techniques for Analysis and Design
Authors: Steve Hoberman
Venue:  (2002)

:A goldmine of valuable tools for data modelers!Data modelers render raw data-names, addresses, and sales totals, for instance-into information such as customer profiles and seasonal buying patterns that can be used for making critical business decisions. This book brings together thirty of the most effective tools for solving common modeling problems. The author provides an example of each tool and describes what it is, why it is needed, and how it is generally used to model data for both databases and data warehouses, along with tips and warnings. Blank sample copies of all worksheets and checklists described are provided in an appendix.Companion Web site features updates on the latest tools and techniques, plus links to related sites offering automated tools. 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
Measuring and evaluating maintenance process using reliability, risk, and test metrics
Authors: N. F. Schneidewind
Venue: Proceedings of the International Conference on Software Maintenance (1997)

In analyzing the stability of a maintenance process, it is important that it not be treated in isolation from the reliability and risk of deploying the software that result from applying the process. Furthermore, we need to consider the efficiency of the test effort that is a part of the process and a determinate of reliability and risk of deployment. Therefore, we integrated these factors into a unified approach. Our contribution to maintenance is the integration and measurement of these factors so that the influence of maintenance actions and test effort on the reliability of the software and the risk of deploying it can be assessed. We use a safety critical application of national visibility-the NASA Space Shuttle-as an example application of the unified approach.