ppxscal/embedding_network huggingface dataset:
Why Not Semijoins for Streams, When Distributed?
Authors: Tri Tran, Byung Suk Lee, Matthew W. Bovee
Venue: Proceedings of the Second International Conference on Digital Telecommunications (2007)

This paper addresses the semijoin-based window join algorithm over distributed data streams. In distributed stream query processing, data streams arriving at remote sites need to be shipped to the processing site for query execution. This typically introduces high communication overhead over the network. Our observation is that semijoin, effective to reduce communication overhead in distributed database query processing, can be also effective in distributed stream query processing. The challenge, of course, lies in the streaming nature of tuples, the processing of which is fundamentally different from processing a set of tuples. We address this challenge by first adapting the window-based stream join to a distributed environment. The resulting join algorithm (called simple join) uses the idea of exporting a window to the query processing site. We then adopt the semijoin to reduce the communication overhead (in return for a marginal increase of the processing overhead). The resulting semijoin-based join algorithm uses the ideas of a mirror window and a partial tuple. That is, it creates a copy of a remote window at the processing site and sends a partial tuple to probe for matching tuples before sending a full tuple. Finally, we analyze the two join algorithms using our proposed cost models and verify the analysis results through a set of experiments.
Active Shape Models with Invariant Optimal Features: Application to Facial Analysis
Authors: Federico M. Sukno Sebastian Ordas Constantine Butakoff Santiago Cruz Alejandro F. Frangi
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2007)

This work is framed in the field of statistical face analysis. In particular, the problem of accurate segmentation of prominent features of the face in frontal view images is addressed. We propose a method that generalizes linear Active Shape Models (ASMs), which have already been used for this task. The technique is built upon the development of a nonlinear intensity model, incorporating a reduced set of differential invariant features as local image descriptors. These features are invariant to rigid transformations, and a subset of them is chosen by Sequential Feature Selection for each landmark and resolution level. The new approach overcomes the unimodality and Gaussianity assumptions of classical ASMs regarding the distribution of the intensity values across the training set. Our methodology has demonstrated a significant improvement in segmentation precision as compared to the linear ASM and Optimal Features ASM (a nonlinear extension of the pioneer algorithm) in the tests performed on AR, XM2VTS, and EQUINOX databases.
Network flow optimizations and distributed control algorithms
Authors: John S. Baras
Venue:  (2006)

This thesis concerns the problem of designing distributed algorithms for achieving efficient and fair bandwidth allocations in a resource constrained network. This problem is fundamental to the design of transmission protocols for communication networks, since the fluid models of popular protocols such as TCP and Proportional Fair Controller can be viewed as distributed algorithms which solve the network flow optimization problems corresponding to some fairness criteria. Because of the convexity of the optimization problem as well as its decoupling structure, there exist classical dual algorithm and primal/dual algorithm which are both distributed. However, the main difficulty is the possible instability of the dynamics of these algorithms caused by transmission delays. We use customized Lyapunov-Krasovskii functionals to obtain the stability conditions for these algorithms in networks with heterogeneous time-varying delays. There are two main features of our results. The first is that these stability conditions can be enforced by a small amount of information exchange among relevant users and links. The second is that these stability conditions only depend on the upper bound of delays, not on the rate of delay variations. We further our discussion on scalable algorithms with minimum information to maintain stability. We present a design methodology for such algorithms and prove the global stability of our scalable controllers by the use of Zames-Falb multipliers. Next we extend this method to design the first scalable and globally stable algorithm for the joint multipath routing and flow optimization problem. We achieve this by adding additional delays to different paths for all users. Lastly we discuss the joint single path routing and flow optimization problem, which is a NP hard problem. We show bounded price of anarchy for combined flow and routing game for simple networks and show for many-user networks, simple Nash algorithm leads to approximate optimum of the problem.
An Interactive Multimedia Diary for the Home
Authors: Gamhewage C. de Silva, Toshihiko Yamasaki, Kiyoharu Aizawa
Venue: Computer (2007)

A system for retrieval and summarization of multimedia data from a home-like environment continuously captures video and audio sequences as the inhabitants are moving inside the house. An interactive user interface based on hierarchical media segmentation incorporates user memory and intelligence data.
A Service-Oriented Approach to Security--Concepts and Issues
Authors: Elisa Bertino, Lorenzo D. Martino
Venue: Proceedings of the 11th IEEE International Workshop on Future Trends of Distributed Computing Systems (2007)

Various mechanisms for authentication and access control have been developed over time. Operating systems and DBMS implement such mechanisms and support quite rich access control models. A major limitation, however, of such mechanisms is that they are not extensible; thus whenever an application domain requires more sophisticated access controls or authentication, the applications must include logics for such controls. Such an approach leads to increased costs in application development and maintenance. For these reasons, models and mechanisms apt to separate those functions have emerged, also fostered by XML and Web services. At the same time, the need to drive the behaviour of security through clearly stated and machine-processable policies has fostered the development of various policy models and policy management mechanisms. A policy-based approach enhances flexibility, and reduces the application development costs. Changes to the access control or authentication requirements simply entail modifying the policies, without requiring changes to the applications. It is thus clear that an important approach to the problem of security is represented by the development of policy-based security services providing all functions for security management relevant to applications. Such an approach is particularly promising for applications organized according to the Service Oriented (SOA) paradigm. In this paper we discuss basic concepts of such an approach to security and we present a reference architectural framework. We discuss three relevant classes of security services, namely digital identity management services, authentication services, access control services, and outline research directions for each such class.
3D optical flow computation using a parallel variational multigrid scheme with application to cardiac C-arm CT motion
Authors: El Mostafa Kalmoun, Harald Köstler, Ulrich Rüde
Venue: Image and Vision Computing (2007)

Motivated by recent applications to 3D medical motion estimation, we consider the problem of 3D optical flow computation in real time. The 3D optical flow model is derived from a straightforward extension of the 2D Horn-Schunck model and discretized using standard finite differences. We compare memory costs and convergence rates of four numerical schemes: Gauss-Seidel and multigrid with three different strategies of coarse grid operators discretization: direct coarsening, lumping and Galerkin approaches. Experimental results to compute 3D motion from cardiac C-arm CT images demonstrate that our variational multi-grid based on Galerkin discretization outperforms significantly the Gauss-Seidel method. The parallel implementation of the proposed scheme using domain partitioning shows that the algorithm scales well up to 32 processors on a cluster of AMD Opteron CPUs which consists of four-way nodes connected by an Infiniband network.
Twisted in Knots
Authors: Minor Gordon
Venue: IEEE Distributed Systems Online (2007)

A review of "Twisted Network Programming Essentials" by Abe Fettig
Architecting the Lumeta firewall analyzer
Authors: Avishai Wool
Venue: Proceedings of the 10th conference on USENIX Security Symposium - Volume 10 (2001)

Practically every corporation that is connected to the Internet has at least one firewall, and often many more. However, the protection that these firewalls provide is only as good as the policy they are configured to implement. Therefore, testing, auditing, or reverse-engineering existing firewall configurations should be important components of every corporation's network security practice. Unfortunately, this is easier said than done. Firewall configuration files are written in notoriously hard to read languages, using vendor-specific GUIs. A tool that is sorely missing in the arsenal of firewall administrators and auditors is one that will allow them to analyze the policy on a firewall. The first passive, analytical, firewall analysis system was the Fang prototype system [MWZ00]. This was the starting point for the new Lumeta Firewall Analyzer (LFA) system. LFA improves upon Fang in many ways. The most significant improvements are that human interaction is limited to providing the firewall configuration, and that LFA automatically issues the "interesting" queries and displays the outputs of all of them, in a way that highlights the risks without cluttering the high-level view. This solves a major usability problem we found with Fang, namely, that users do not know which queries to issue. The input to the LFA consists of the firewall's routing table, and the firewall's configuration files. The LFA parses these various low-level, vendor-specific, files, and simulates the firewall's behavior against all the packets it could possibly receive. The simulation is done completely offline, without sending any packets. The administrator gets a comprehensive report showingwhich types of traffic the firewall allows to enter from the Internet into the customer's intranet and which types of traffic are allowed out of the intranet. The LFA's report is presented as a set of explicit web pages, which are rich with links and cross references to further detail (allowing for easy drill-down). This paper describes the design and architecture of the LFA.
Cachier: A Tool for Automatically Inserting CICO Annotations
Authors: Trishul M. Chilimbi, James R. Larus
Venue: Proceedings of the 1994 International Conference on Parallel Processing - Volume 02 (1994)

Shared memory in a parallel computer provides programmers with the valuable abstraction of a shared address space--through which any part of a computation can access any datum Although uniform access simplifies programming, it also hides communication, which can lead to inefficient programs The check-in, check-out (CICO) performance model for cache-coherent, shared-memory parallel computers helps a programmer identify the communication underlying memory references and account for its cost CICO consists of annotations that a programmer can use to elucidate communication and a model that attributes costs to these annotations The annotations can also serve as directives to a memory system to improve program performance Inserting CICO annotations requires reasoning about the dynamic cache behavior of a program, which is not always easy This paper describes Cachier, a tool that automatically inserts CICO annotations into shared-memory programs A novel feature of this tool is its use of both dynamic information, obtained from a program execution trace, as well as static information, obtained from program analysis We measured several benchmarks annotated by Cachier by running them on a simulation of the DiriSW cache coherence protocol [10], which supports these directives The results show that programs annotated by Cachier perform significantly better than both programs without CICO annotations and programs that were annotated by hand
Feature selection using general regression neural networks for the automatic detection of clustered microcalcifications
Authors: Songyang Yu
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1999. on 1999 IEEE International Conference - Volume 02 (1999)

General regression neural networks (GRNNs) are proposed for selecting the most discriminating features for the automatic detection of clustered microcalcifications in digital mammograms. Previously, We have designed an image processing system for detecting clustered microcalcifications. The system uses wavelet coefficients and feed forward neural networks to identify possible microcalcification pixels and a set of structure features to locate individual microcalcifications. In this work, more features are extracted, and the most discriminating features are selected through the analysis of the GRNNs. The selected features are incorporated into our image processing system and applied to a database of 40 mammograms (Nijmegen database) containing 105 clusters of microcalcifications. Free response operating characteristics (FROG) curves are used to evaluate the performance. Results show that, by incorporating the proposed feature selection scheme, the performance of our system is improved significantly.
A Flexible Hybrid Architecture for Management of Distributed Web Service Registries
Authors: Afiya Kassim, Babak Esfandiari, Shikharesh Majumdar, Laura Serghi
Venue: Proceedings of the Fifth Annual Conference on Communication Networks and Services Research (2007)

This paper proposes an adaptive architecture for Web service registries that changes topology based on system state and user requirements. Three distributed registry topologies are presented and analysed based on their delay and network traffic. An adaptive registry deployment architecture is proposed that uses a communication overlay layer. The interconnection topology is changed based on the state of the system.
Task-based Hardware Reconfiguration in Mobile Robots Using FPGAs
Authors: Sesh Commuri, V. Tadigotla, L. Sliger
Venue: Journal of Intelligent and Robotic Systems (2007)

This paper presents a methodology for the realization of intelligent, task-based reconfiguration of the computational hardware for mobile robot applications. Task requirements are first partitioned into requirements on the system hardware and software. Architecture is proposed that enables these requirements to be addressed through appropriate hardware and software components. Hardware---software co-design and hardware reconfiguration are utilized to design robotic systems that are fault-tolerant and have improved reliability. It is shown that this design enables the implementation of efficient controllers for each task of the robot thereby permitting better operational efficiency using fixed computational resources. The approach is validated through case studies where a team of robots is configured and the behavior of the robots is dynamically modified at run-time. It is demonstrated through this implementation that the design procedure results in increased flexibility in configuration at run-time. The ability to reconfigure the resources also aids collaboration between robots, and results in improved performance and fault tolerance.
Generating Referring Expressions: Making Referents Easy to Identify
Authors: Ivandré Paraboni, Kees van Deemter, Judith Masthoff
Venue: Computational Linguistics (2007)

It is often desirable that referring expressions be chosen in such a way that their referents are easy to identify. This article focuses on referring expressions in hierarchically structured domains, exploring the hypothesis that referring expressions can be improved by including logically redundant information in them if this leads to a significant reduction in the amount of search that is needed to identify the referent. Generation algorithms are presented that implement this idea by including logically redundant information into the generated expression, in certain well-circumscribed situations. To test our hypotheses, and to assess the performance of our algorithms, two controlled experiments with human subjects were conducted. The first experiment confirms that human judges have a preference for logically redundant expressions in the cases where our model predicts this to be the case. The second experiment suggests that readers benefit from the kind of logical redundancy that our algorithms produce, as measured in terms of the effort needed to identify the referent of the expression.
Overview of the TREC 2006 ciQA task
Authors: Diane Kelly, Jimmy Lin
Venue: ACM SIGIR Forum (2007)

Growing interest in interactive systems for answering complex questions lead to the development of the complex, interactive QA (ciQA) task, introduced for the first time at TREC 2006. This paper describes the rationale and design of the ciQA task and the evaluation results. Thirty complex relationship questions based on five question templates were investigated using the AQUAINT collection of newswire text. Interaction forms were the primary vehicle for defining and capturing user-system interactions. In total, six groups participated in the ciQA task and contributed ten different sets of interaction forms. There were two main findings: baseline IR techniques are competitive for complex QA and interaction, at least as defined and implemented in this evaluation, did not appear to improve performance by much.
Action-based slant perception in real and virtual environments
Authors: Nicholaos Mourkoussis, Fiona Rivera, Tom Troscianko, Katerina Mania, Rycharde Hawkes
Venue: Proceedings of the 4th symposium on Applied perception in graphics and visualization (2007)

An innovative action-based motoric measure of slant is proposed, based on gait. This measure is ecologically-valid derived from the angle that the foot makes in relation to the horizontal ground plane immediately before impact (Figure 1). This work explores whether the proposed measure is affected by factors such as material of the walking surface and inclination of the walking ramps. Moreover, experimental studies were conducted in a real environment set-up and in its virtual counterpart. Comparisons between real-world spatial judgments and simulation equivalents provide performance benchmarks as well as tools to assess whether a technological set-up would be of similar functional fidelity to a real-world task situation.
A Parallel Scheduling Method for Efficient Query Processing
Authors: A. Hameurlain, F. Morvan
Venue: Proceedings of the 1993 International Conference on Parallel Processing - Volume 03 (1993)

In this paper, we propose a method to determine parallel scheduling for SQL query operations. The parallelization strategy consists in determining a parallel scheduling based on serial methods. The criteria for operations scheduling is based on deadlines and consideration of the number of processors. Performance evaluation shows the efficiency of each type of parallelism (intra-operation and inter-operation) as a function of the number of processors.
Ontimemeasure: a scalable framework for scheduling active measurements
Authors: P. Calyam, Chang-Gun Lee, D. Krymskiy, D. Lee
Venue: Proceedings of the End-to-End Monitoring Techniques and Services on 2005. Workshop (2005)

In order to satisfy and maintain service level agreements (SLAs), which demand high network availability and good network health, ISPs have started instrumenting their networks with network measurement infrastructures (NMIs) that are composed of dedicated measurement servers. Active measurements are frequently used in NMIs to regularly monitor network health and analyze the experience of end-user application traffic traversing the network. However, active measurements initiated by measurement servers need to be regulated. Unregulated active measurement traffic can cause an unpredictable negative impact on the actual application traffic. Also, running simultaneous conflicting active measurements on measurement servers could result in misleading reports of network performance. In this paper, we describe our active measurements scheduling framework called "OnTimeMeasure" that allows ISPs to regulate the amount of active measurement traffic injected into the network and also prevents conflicts in ongoing active measurements between measurement servers. OnTimeMeasure provides a simple scripting language interface to specify various measurement requirements such as physical topology of measurement server clusters, periodicity of the measurements, and properties of measurement tools. For a given measurement requirements script, OnTimeMeasure uses an efficient heuristic bin-packing algorithm to generate measurement timetables for orchestrating active measurements for a network involving multiple measurement servers, each hosting multiple measurement tools.
Minimization of axiom sets on fuzzy approximation operators
Authors: Xiao-Ping Yang
Venue: Information Sciences: an International Journal (2007)

Axiomatic characterization of approximation operators is an important aspect in the study of rough set theory. In this paper, we examine the independence of axioms and present the minimal axiom sets characterizing fuzzy rough approximation operators and rough fuzzy approximation operators.
Scalable Clustering with smoka
Authors: Jacob Kogan
Venue: Proceedings of the International Conference on Computing: Theory and Applications (2007)

The paper reports a multi-step clustering procedure equipped with a divergence (a distance like function derived from a convex function). The first step of the procedure is a BIRCH like algorithm capable to convert very large datasets to "summaries" that require much less computer memory. The second step is the Principal Direction Divisive Partitioning algorithm (PDDP) that partitions the set of "summaries" into k clusters. This partition is the input for a smoothed k-means based clustering algorithm (smoka). The final partition of "summaries" generated by smoka induces a partition of the original dataset. Preliminary numerical experiments with text collections reported in the paper demonstrate smoka's remarkable accuracy and speed of convergence.
pClock: an arrival curve based approach for QoS guarantees in shared storage systems
Authors: Ajay Gulati, Arif Merchant, Peter J. Varman
Venue: ACM SIGMETRICS Performance Evaluation Review (2007)

Storage consolidation is becoming an attractive paradigm for data organization because of the economies of sharing and the ease of centralized management. However, sharing of resources is viable only if applications can be isolated from each other. This work targets the problem of providing performance guarantees to an application irrespective of the behavior of other workloads. Application requirements are represented in terms of the average throughput, latency and maximum burst size. Most earlier schemes only do weighted bandwidth allocation; schemes that provide control of latency either cannot handle bursts or penalize applications for their own prior behavior, such as using spare capacity. Our algorithm pClock is based on arrival curves that intuitively capture the bandwidth and burst requirements of applications. We show analytically that an application following its arrival curve never misses its deadline. We have implemented pClock both in DiskSim and as a module in the Linux kernel 2.6. Our evaluation shows three important features of pClock: (1) benefits over existing algorithms; (2) efficient performance isolation and burst handling; and (3) the ability to allocate spare capacity to either speed up some applications or to a background utility, such as backup. pClock can be efficiently implemented in a system without much overhead.