ppxscal/embedding_network huggingface dataset:
Parallelizing query optimization
Authors: Wook-Shin Han, Wooseong Kwak, Jinsoo Lee, Guy M. Lohman, Volker Markl
Venue: Proceedings of the VLDB Endowment (2008)

Many commercial RDBMSs employ cost-based query optimization exploiting dynamic programming (DP) to efficiently generate the optimal query execution plan. However, optimization time increases rapidly for queries joining more than 10 tables. Randomized or heuristic search algorithms reduce query optimization time for large join queries by considering fewer plans, sacrificing plan optimality. Though commercial systems executing query plans in parallel have existed for over a decade, the optimization of such plans still occurs serially. While modern microprocessors employ multiple cores to accelerate computations, parallelizing query optimization to exploit multi-core parallelism is not as straightforward as it may seem. The DP used in join enumeration belongs to the challenging nonserial polyadic DP class because of its non-uniform data dependencies. In this paper, we propose a comprehensive and practical solution for parallelizing query optimization in the multi-core processor architecture, including a parallel join enumeration algorithm and several alternative ways to allocate work to threads to balance their load. We also introduce a novel data structure called skip vector array to significantly reduce the generation of join partitions that are infeasible. This solution has been prototyped in PostgreSQL. Extensive experiments using various query graph topologies confirm that our algorithms allocate the work evenly, thereby achieving almost linear speed-up. Our parallel join enumeration algorithm enhanced with our skip vector array outperforms the conventional generate-and-filter DP algorithm by up to two orders of magnitude for star queries-linear speedup due to parallelism and an order of magnitude performance improvement due to the skip vector array.
GADA 2008 PC Co-chairs' Message
Authors: Pilar Herrero, Daniel Katz, María S. Pérez, Dennis Gannon
Venue: Proceedings of the OTM 2008 Confederated International Conferences, CoopIS, DOA, GADA, IS, and ODBASE 2008. Part I on On the Move to Meaningful Internet Systems: (2008)

This volume contains the papers presented at GADA 2008, the International Symposium on Grid Computing,High-Performance and Distributed Applications. The purpose of the GADA series of conferences, held within the framework of the OnTheMove Federated Conferences (OTM), is to bring together researchers, developers, professionals and students in order to advance research and development in the areas of grid computing and distributed systems and applications. This year's conference was held in Monterrey, Mexico, November 13-14, 2008.
On the space---time of optimal, approximate and streaming algorithms for synopsis construction problems
Authors: Sudipto Guha
Venue: The VLDB Journal &mdash; The International Journal on Very Large Data Bases (2008)

Synopses construction algorithms have been found to be of interest in query optimization, approximate query answering and mining, and over the last few years several good synopsis construction algorithms have been proposed. These algorithms have mostly focused on the running time of the synopsis construction vis-a-vis the synopsis quality. However the space complexity of synopsis construction algorithms has not been investigated as thoroughly. Many of the optimum synopsis construction algorithms are expensive in space. For some of these algorithms the space required to construct the synopsis is significantly larger than the space required to store the input. These algorithms rely on the fact that they require a smaller "working space" and most of the data can be resident on disc. The large space complexity of synopsis construction algorithms is a handicap in several scenarios. In the case of streaming algorithms, space is a fundamental constraint. In case of offline optimal or approximate algorithms, a better space complexity often makes these algorithms much more attractive by allowing them to run in main memory and not use disc, or alternately allows us to scale to significantly larger problems without running out of space. In this paper, we propose a simple and general technique that reduces space complexity of synopsis construction algorithms. As a consequence we show that the notion of "working space" proposed in these contexts is redundant. This technique can be easily applied to many existing algorithms for synopsis construction problems. We demonstrate the performance benefits of our proposal through experiments on real-life and synthetic data. We believe that our algorithm also generalizes to a broader range of dynamic programs beyond synopsis construction.
Maximum principle for optimal control of two-directionally continuous linear repetitive processes
Authors: Dariusz Idczak
Venue: Multidimensional Systems and Signal Processing (2008)

In the paper, maximum principle for a two-directionally continuous variant of a linear autonomous repetitive process with cost functional depending on a fixed "end-function" is obtained. Maximum condition has a pointwise form, a conjugate system has a Fornasini-Marchesini form. The result is derived from the extremum principle for smooth-convex problems, due to Ioffe and Tikhomirov.
Terrestrial laser scanner and retro-reflective targets: an experiment for anomalous effects investigation
Authors: A. Pesci, G. Teza
Venue: International Journal of Remote Sensing (2008)

Artificial targets are generally used in terrestrial laser scanner (TLS) practice for data georeferencing. This is because they are well recognized and modelled from the point cloud and their positions can be contemporarily measured by topographical techniques. The accuracy of target identification directly influences the georeferencing quality. In particular, retro-reflective materials can cause anomalies in range measurement due to the too high amplitude of the returned pulse. If the received pulse intensity exceeds the limits of the sensor dynamic range, the receiver saturates, producing a truncated pulse preventing the correct time-of-flight computation. A series of experiments was performed in order to test the performances of a specific instrument (Optech ILRIS 3D) for the acquisition of artificial targets made of retro-reflective material, resulting in very high reflectance. Dealing with ranges lower than about 300 m, two cases were clearly observed: the wrong distance measurement of points over high reflecting surfaces and the presence of haloes around these surfaces. Neglecting these phenomena has serious implications and can lead to wrong georeferencing. Experiments were executed and data was analysed, providing a qualitative and semi-quantitative phenomenon description. Finally, the design of a target that can be easily recognized and correctly modelled was proposed.
Motion estimation, segmentation and separation, using hypercomplex phase correlation, clustering techniques and graph-based optimization
Authors: Dimitrios S. Alexiadis, George D. Sergiadis
Venue: Computer Vision and Image Understanding (2009)

The problem of estimating the motions in image sequences has been extensively studied. However, most of the proposed motion estimation approaches deal only with the luminance component of the images, although the color information is also important. The usual way to apply these techniques in color image sequences is to process each color channel separately. As proposed by Ell, Sangwine and Moxey, a more sophisticated approach is to handle the color channels in a ''holistic'' manner, using quaternions. We present a motion estimation approach which is based on the Hypercomplex (quaternionic) Phase Correlation of Moxey et al. We show that the quaternionic approach is computationally more efficient and more robust to sensor noise, compared with the corresponding three-channels-separately approach. With the assumption of smoothly time-varying velocities we propose the application of a weighted fuzzy c-means clustering procedure to the obtained velocity estimates. This renders the estimation more robust. A methodology in the hypercomplex Fourier transform domain for separating the moving objects/layers is also presented. An energy-minimization-based approach for the spatial assignment of the velocities and the creation of segmentation maps, is given. We furthermore show how to apply the motion estimation approach locally in space for the extraction of dense motion fields. Our experimental results and comparisons with state-of-the-art methodologies verify the effectiveness of the proposed approach.
Real-time evaluation of radio access technology selection policies in heterogeneous wireless systems: the AROMA testbed approach
Authors: Miguel López-Benítez, Nemanja Vučević, Francisco Bernardo, Anna Umbert
Venue: Proceedings of the 11th international symposium on Modeling, analysis and simulation of wireless and mobile systems (2008)

This paper presents and describes the real-time testbed for all-IP Beyond 3G heterogeneous wireless networks that has been developed in the framework of the European IST AROMA project. The main objective of the AROMA testbed is to provide an advanced and realistic framework where the benefits of the algorithms developed within the AROMA project for both the radio access network and core network parts, as well as for the management of the end-to-edge quality of service, can be demonstrated. In particular, this paper focuses on the radio access part of the testbed, providing an in-depth description of its implementation and showing performance results with numerous supporting data that demonstrate the potentials and capabilities of the developed tool for the real-time evaluation of Radio Access Technology (RAT) selection policies under realistic scenarios. To this end, the behavior of two innovative RAT selection algorithms recently proposed in the literature has been assessed, analyzed, and compared in order to demonstrate the applicability of the tool.
A coordination framework for Cooperative Information Gathering
Authors: Issam Bouslimi, Chihab Hanachi, Hassan Tout, Khaled Ghedira
Venue: International Journal of Advanced Intelligence Paradigms (2008)

Cooperative Information Gathering Systems (CIGS) require the coordination of multiple agents executing tasks in a distributed, open and heterogeneous setting. In this complex and highly interactive context, it is essential to include explicit coordination models to ensure the coherent and efficient behaviour of cooperative agents. The paper identifies the three main issues which are essential for addressing this problem and expresses them in three interrelated models. The information model is implemented in Protege as a combination of an OWL ontology and SWRL rules. The task and organisational models are represented by High Level Petri Nets and extended And/Or graphs.
Designing and evaluating multimodal interaction for mobile contexts
Authors: Saija Lemmelä, Akos Vetek, Kaj Mäkelä, Dari Trendafilov
Venue: Proceedings of the 10th international conference on Multimodal interfaces (2008)

In this paper we report on our experience on the design and evaluation of multimodal user interfaces in various contexts. We introduce a novel combination of existing design and evaluation methods in the form of a 5-step iterative process and show the feasibility of this method and some of the lessons learned through the design of a messaging application for two contexts (in car, walking). The iterative design process we employed included the following five basic steps: 1) identification of the limitations affecting the usage of different modalities in various contexts (contextual observations and context analysis) 2) identifying and selecting suitable interaction concepts and creating a general design for the multimodal application (storyboarding, use cases, interaction concepts, task breakdown, application UI and interaction design), 3) creating modality-specific UI designs, 4) rapid prototyping and 5) evaluating the prototype in naturalistic situations to find key issues to be taken into account in the next iteration. We have not only found clear indications that context affects users' preferences in the usage of modalities and interaction strategies but also identified some of these. For instance, while speech interaction was preferred in the car environment users did not consider it useful when they were walking. 2D (finger strokes) and especially 3D (tilt) gestures were preferred by walking users.
Design of a modified Bi-directional SOVA
Authors: Kingsley Oteng-Amoako, Saeid Nooshabadi
Venue: WSEAS TRANSACTIONS on COMMUNICATIONS (2007)

In this paper, a directional bi-directional Soft-Output Viterbi algorithm (SOVA) based Turbo decoder architecture is proposed. By performing an extra pass through the decoder trellis, effectively bi-directional decoding, decoder performance can be improved. The bi-directional decoding results in a 60% increase in operations over the conventional SOVA decoder, while incurring no significant increase in architecture size. The paper also proposes the use of extrinsic information in selecting the SOVA algorithm, resulting in improved decoding performance. The use of the extrinsic information as a reliability measure does not introduce any inherent latency and requires a negligible increase in hardware. Following both architecture proposals, the paper discusses practical implementation using finite precise arithmetic. Simulation results show that by combining both proposed techniques, an extra coding gain of 0.4dB can be obtained over the conventional SOVA decoder in an Additive White Gaussian Noise (AWGN) channel.
ProCope—protein complex prediction and evaluation
Authors: Jan Krumsiek, Caroline C. Friedel, Ralf Zimmer
Venue: Bioinformatics (2008)

Summary: Recent advances in high-throughput technology have increased the quantity of available data on protein complexes and stimulated the development of many new prediction methods. In this article, we present ProCope, a Java software suite for the prediction and evaluation of protein complexes from affinity purification experiments which integrates the major methods for calculating interaction scores and predicting protein complexes published over the last years. Methods can be accessed via a graphical user interface, command line tools and a Java API. Using ProCope, existing algorithms can be applied quickly and reproducibly on new experimental results, individual steps of the different algorithms can be combined in new and innovative ways and new methods can be implemented and integrated in the existing prediction framework. Availability: Source code and executables are available at http://www.bio.ifi.lmu.de/Complexes/ProCope/ Contact: Caroline.Friedel@bio.ifi.lmu.de
Customizable pattern-oriented verifiers for web applications
Authors: Nhor Sok Lang, Takao Shimomura, Quan Liang Chen, Kenji Ikeda
Venue: WSEAS Transactions on Information Science and Applications (2007)

This paper presents a method that enables programmers to easily define and customize verification items for Web applications. In this method, we first specify verification conditions using regular expressions to indicate a part of code of interest, and if it is against a verification item, this method provides a mechanism to automatically correct that code using another expression. In addition, to make it possible to easily define complicated verification items that check a sequence of the pieces of program code that appear at multiple locations of the programs, the method provides several program interfaces with which we can check the part of the program code of interest in more detail.
EufDpll - A Tool to Check Satisfiability of Equality Logic Formulas
Authors: Olga Tveretina, Wieger Wesselink
Venue: Electronic Notes in Theoretical Computer Science (ENTCS) (2009)

Decision procedures for subsets of First-Order Logic form the core of many verification tools. Applications include hardware and software verification. The logic of Equality with Uninterpreted Functions (EUF) is a decidable subset of First-Order Logic. The EUF logic and its extensions have been applied for proving equivalence between systems. We present a branch and bound decision procedure for EUF logic based on the generalisation of the Davis-Putnam-Loveland-Logemann procedure (EUF-DPLL). EufDpll is a tool to check satisfiability of EUF formulas based on this procedure.
Multi-Processor SoC-Based Design Methodologies Using Configurable and Extensible Processors
Authors: Grant Martin
Venue: Journal of Signal Processing Systems (2008)

The growing interest in multiprocessor system-on-chip (MPSoC) design, or `multicore' processors, has resulted in some confusion between the various types of multiprocessor architectures and their suitability in different application spaces. In particular, there are clear differences between the general-purpose, symmetric multiprocessor (SMP) approaches, and the application-specific, asymmetric multiprocessor (AMP) architectures. Configurable and extensible processors are especially suited for the AMP approach, yet their flexibility means that new design methodologies and tools must be developed to allow effective utilisation of multiple instruction-set processors in a complex design. Configurable and extensible processors are especially well suited for data-intensive computational tasks, such as are found in many signal and image processing applications, including audio, video, and wireless and wired networking. A design methodology for such applications must pay careful attention to the right programming models, and dataflow styles of processing seem a natural fit to the application space. In this paper, we describe a design methodology, flow and tools for MPSoC design using configurable and extensible processors that is especially interesting for data-intensive dataflow style applications. Some of the issues involved in this design approach are used to highlight opportunities for ongoing research.
Dev 2.0: model driven development in the cloud
Authors: Gautam Shroff
Venue: Proceedings of the 16th ACM SIGSOFT International Symposium on Foundations of software engineering (2008)

In recent years the term Web 2.0 has been used to describe the transformation of the internet from a world of publishers and readers to one of collaborators where everyone is a creator of content, and 'communities' bind participants in an ecosystem. We have also seen the success of some software as a service (SaaS) applications, such as Salesforce.com, to the extent that application development is itself available as a hosted service (Salesforce's AppExchange, Coghead, etc.). We call this 'Dev 2.0', where the line between users and developers is blurred, and an application is available to all stakeholders through the life-cycle as it evolves.
Can people collaborate to improve the relevance of search results?
Authors: Arun Kumar Agrahri, Divya Anand Thattandi Manickam, John Riedl
Venue: Proceedings of the 2008 ACM conference on Recommender systems (2008)

Search engines are among the most-used resources on the internet. However, even today's most successful search engines struggle to provide high quality search results. According to recent studies as many as 50 percent of web search sessions fail to find any relevant results for the searcher. Researchers have proposed social search techniques, in which early searchers provide feedback that is used to improve relevance for later searchers. In this paper we investigate foundational questions of social search. In particular, we directly assess the degree of agreement among users about the relevance ranking of search results. We developed a simulated search engine interface that systematically randomizes Google's normal relevance ordering of the items presented to users. Our results show that (a) people are biased toward items in the top of the search lists, even if the list is randomized; (b) people explicit feedback is not biased and (c) people's shared preferences do not always agree with Google's result order. These results suggest that social search techniques might improve the effectiveness of web search engines.
Adaptive and Probabilistic Power Control Algorithms for RFID Reader Networks
Authors: Kainan Cha, Anil Ramachandran, Sarangapani Jagannathan
Venue: International Journal of Distributed Sensor Networks (2008)

In radio frequency identification (RFID) systems, the detection range and read rates will suffer from interference among high power reading devices. This problem grows severely and degrades system performance in dense RFID networks. Consequently, medium access protocols (MAC) protocols are needed for such networks to assess and provide access to the channel so that tags can be read accurately. In this paper, we investigate a suite of feasible power control schemes to ensure overall coverage area of the system while maintaining a desired read rate. The power control scheme and MAC protocol dynamically adjusts the RFID reader power output in response to the interference level seen during tag reading and acceptable signal-to-noise ratio (SNR). We present novel distributed adaptive power control (DAPC) and probabilistic power control (PPC) as two possible solutions. A suitable back off scheme is also added with DAPC to improve coverage. Both the methodology and implementation of the schemes are presented, simulated, compared, and discussed for further work.
Simulation research of fuzzy-PID synthesis yaw vector control system of wind turbine
Authors: Piao Haiguo, Wang Zhixin
Venue: WSEAS Transactions on Systems and Control (2007)

Enhancing the stability and robust of yawing system effectively, carrying out the simulation research of fuzzy-PID synthesis control. Designing the yawing vector control system with the synthesis controller of fuzzy-PID, modeling the system with Matlab simulation software, and taking simulation test. Comparing the simulation curves with common PID control and fuzzy PID subsection control, the result indicate that the fuzzy-PID synthesis control system has better performances in the stability and robust of yawing system, which increase the safety factor of system.
Finding relevant patterns in bursty sequences
Authors: Alexander Lachmann, Mirek Riedewald
Venue: Proceedings of the VLDB Endowment (2008)

Sequence data is ubiquitous and finding frequent sequences in a large database is one of the most common problems when analyzing sequence data. Unfortunately many sources of sequence data, e.g., sensor networks for data-driven science, RFID-based supply chain monitoring, and computing system monitoring infrastructure, produce a challenging workload for sequence mining. It is common to find bursts of events of the same type. Such bursts result in high mining cost, because input sequences are longer. An even greater challenge is that these bursts tend to produce an overwhelming number of irrelevant repetitive sequence patterns with high support. Simply raising the support threshold is not a solution, because at some point interesting sequences will get eliminated. As an alternative we propose a novel transformation of the input sequences. We show that this transformation has several desirable properties. First, the transformed data can still be mined with existing sequence mining algorithms. Second, for a given support threshold the mining result can often be obtained much faster and it is usually much smaller and easier to interpret. Third, and most importantly, we show that the result sequences retain the important characteristics of the sequences that would have been found in the original (not transformed) data. We validate our technique with an experimental study using synthetic and real data.