ppxscal/embedding_network huggingface dataset:
Competitive prefetching for concurrent sequential I/O
Authors: Chuanpeng Li, Kai Shen, Athanasios E. Papathanasiou
Venue: Proceedings of the 2nd ACM SIGOPS/EuroSys European Conference on Computer Systems 2007 (2007)

During concurrent I/O workloads, sequential access to one I/O stream can be interrupted by accesses to other streams in the system. Frequent switching between multiple sequential I/O streams may severely affect I/O efficiency due to long disk seek and rotational delays of disk-based storage devices. Aggressive prefetching can improve the granularity of sequential data access in such cases, but it comes with a higher risk of retrieving unneeded data. This paper proposes a competitive prefetching strategy that controls the prefetching depth so that the overhead of disk I/O switch and unnecessary prefetching are balanced. The proposed strategy does not require a-priori information on the data access pattern, and achieves at least half the performance (in terms of I/O throughput) of the optimal offline policy. We also provide analysis on the optimality of our competitiveness result and extend the competitiveness result to capture prefetching in the case of random-access workloads. We have implemented the proposed competitive prefetching policy in Linux 2.6.10 and evaluated its performance on both standalone disks and a disk array using a variety of workloads (including two common file utilities, Linux kernel compilation, the TPC-H benchmark, the Apache web server, and index searching). Compared to the original Linux kernel, our competitive prefetching system improves performance by up to 53%. At the same time, it trails the performance of an oracle prefetching strategy by no more than 42%.
Applying a Flexible Mining Architecture to Intrusion Detection
Authors: Marcello Castellano, Giuseppe Mastronardi, Angela Aprile, Giuliano Bellone de Grecis, Flaviano Fiorino
Venue: Proceedings of the The Second International Conference on Availability, Reliability and Security (2007)

Data mining is becoming a pervasive technology in several activities as using historical data to predict the success of a marketing campaign, looking for patterns in financial transactions to discover illegal activities or analyzing genome sequences. In this paper we adopt a reference flexible mining architecture able to discover knowledge in a distributed and heterogeneous environment. In the context of security, the information we are seeking is the knowledge of whether a security breach has been experienced, and if the answer is yes, who is the perpetrator. To this purpose, the guide lines of the Service Oriented Architecture, SOA, and the Orchestration model have been considered as a way to realize a our proposal of Knowledge Discovery Process to Intrusion Detection.
Second-Order Cone Programming Relaxation of Sensor Network Localization
Authors: Paul Tseng
Venue: SIAM Journal on Optimization (2007)

The sensor network localization problem has been much studied. Recently Biswas and Ye proposed a semidefinite programming (SDP) relaxation of this problem which has various nice properties and for which a number of solution methods have been proposed. Here, we study a second-order cone programming (SOCP) relaxation of this problem, motivated by its simpler structure and its potential to be solved faster than SDP. We show that the SOCP relaxation, though weaker than the SDP relaxation, has nice properties that make it useful as a problem preprocessor. In particular, sensors that are uniquely positioned among interior solutions of the SOCP relaxation are accurate up to the square root of the distance error. Thus, these sensors, which are easily identified, are accurately positioned. In our numerical simulation, the interior solution found can accurately position up to 80-90&percent; of the sensors. We also propose a smoothing coordinate gradient descent method for finding an interior solution that is faster than an interior-point method.
Digitally Evolving Models for Dynamically Adaptive Systems
Authors: Heather J. Goldsby, David B. Knoester, Betty H. C. Cheng, Philip K. McKinley, Charles A. Ofria
Venue: Proceedings of the 2007 International Workshop on Software Engineering for Adaptive and Self-Managing Systems (2007)

Developing a Dynamically Adaptive System (DAS) requires a developer to identify viable target systems that can be adopted by the DAS at runtime in response to specific environmental conditions, while satisfying critical properties. This paper describes a preliminary investigation into using digital evolution to automatically generate models of viable target systems. In digital evolution, a population of selfreplicating computer programs exists in a user-defined computational environment and is subject to instruction-level mutations and natural selection. These "digital organisms" have no built-in ability to generate a model - each population begins with a single organism that only has the ability to self-replicate. In a case study, we demonstrate that digital evolution can be used to evolve known state diagrams and to further evolve these diagrams to satisfy system critical properties. This result shows that digital evolution can be used to aid in the discovery of the viable target systems of a DAS.
Architectural Analysis of Multicast Routing Protocols for Wireless Ad Hoc Networks
Authors: Dewan Tanvir Ahmed, Shervin Shirmohammadi
Venue: Proceedings of the Sixth International Conference on Networking (2007)

Wireless ad hoc network is a dynamic network with the commitment of cooperative nodes. Multicasting is intended for group communication that supports the dissemination of information from a sender to all the receivers in a group. The difficulties of ad hoc networks are the scarcity of bandwidth, short lifetime due to power constraint, dynamic topology caused by nodes' mobility, etc. These problems put in force to design simple, robust and energy efficient multicast routing protocols for this environment. In this paper, we discuss the architecture of different multicast routing protocols, address their deployment issues and provide a guideline for the researchers in this field.
Analysis of two structures for combined acoustic echo cancellation and noise reduction
Authors: Y. Guelou
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1996. on Conference Proceedings., 1996 IEEE International Conference - Volume 02 (1996)

We address the problem of speech enhancement in the context of GSM hands-free radiotelephony where the signal to be transmitted is corrupted by background noise and echo signals. We propose possible schemes for combined acoustic echo cancellation (AEC) and noise reduction (NR) devices. Considering two AEC algorithms and one NR device, we show that the overall performance obtained by these schemes are greatly dependent on the intrinsic behaviour of the considered AEC algorithms. These results are confirmed by the informal listening tests presented.
Design of the optimal separating hyperplane for the decision feedback equalizer using support vector machines
Authors: S. Chen
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 2000. on IEEE International Conference - Volume 05 (2000)

The conventional decision feedback equalizer (DFE) separates the different signal classes using a single hyperplane. It is well known that the popular minimum mean square error (MMSE) design is generally not the optimal minimum bit error rate (MBER) solution. We propose a method of designing the separating hyperplane for the conventional DFE based on support vector machines (SVMs). The SVM design achieves asymptotically the MBER solution and can be computed efficiently.
Using portfolios in the classroom
Authors: J. E. Sharp
Venue: Proceedings of the Frontiers in Education Conference,1997. on 27th Annual Conference. Teaching and Learning in an Era of Change. - Volume 01 (1997)

This paper presents a review of the literature (including World Wide Web sources) and a discussion of using student portfolios in the college classroom. Topics discussed are the definition of portfolios, contents, uses, evaluation methods, effectiveness and suggested sources for further research. Specifics from various college courses, including engineering, writing, mathematics, and science courses, illustrate the concepts. Three engineering courses are showcased to give an overview of differences in portfolio types, contents and evaluation. 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
Time-shared TMR for fault-tolerant CORDIC processors
Authors: Jae-Hyuck Kwak
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 200. on IEEE International Conference - Volume 02 (2001)

Presents a low-cost approach to concurrent error correction in high-performance CORDIC processors by using time-shared triple modular redundancy. Operands are partitioned into three sets of disjoint digits and operations are performed three times on different hardware components to correct possible errors by majority voting. The approach has limited latency increase and throughput reduction. Pipelining can be used to maintain the same throughput as a conventional design.
Time-Compression of Speech in Information Talks Using Spectral Entropy
Authors: Mohammed Ajmal, Azadeh Kushki, Konstantinos N. Plataniotis
Venue: Proceedings of the Eight International Workshop on Image Analysis for Multimedia Interactive Services (2007)

Speech is one of the richest sources of information in human communication. In several situations, for example, classroom lectures, speech data alone conveys the majority of pertinent information [1]. Large speech archives of lecture material are increasingly available on the Internet, but the lack of effective audio skimming tools complicates the interaction between users and audio material. In this paper, we describe a novel method for time-compression of speech based on the information theoretic measure of entropy. We demonstrate the applicability of spectral entropy in identifying important segments in speech, enabling time-compression of speech for skimming. We present results from a user study which confirms the viability of our approach.
Safe at any speed: fast, safe parallelism in servers
Authors: John Jannotti, Kiran Pamnany
Venue: Proceedings of the 2nd conference on Hot Topics in System Dependability - Volume 2 (2006)

Many applications take advantage of parallelism to increase performance. Servers are a particularly common case as they must multiplex resources across many simultaneous users. Unfortunately, writing concurrent applications is difficult and prone to subtle and non-deterministic bugs that are difficult to reproduce. We advocate an approach to developing concurrent programs that is safe by default. Conservative static analysis determines when two code segments may safely run in parallel, and a runtime scheduler respects these constraints. We have built an analyzer for event-driven servers that discovers data sharing to find safe parallelism among event handlers. As a prototype, the analysis currently considers only global data, assuming that request-specific data structures passed to event handlers are completely independent. We have also begun work on a runtime system that schedules event handler execution within the constraints determined by the analyzer. For performance reasons, the scheduler makes additional conservative assumptions about contention. We have analyzed thttpd, an event-driven web server. We show how our system can be used to increase performance without complex synchronization schemes.
Terrain Modelling for Planetary Exploration
Authors: Ioannis Rekleitis, Jean-Luc Bedwani, Sebastien Gemme, Tom Lamarche, Erick Dupuis
Venue: Proceedings of the Fourth Canadian Conference on Computer and Robot Vision (2007)

The success of NASA's Mars Exploration Rovers has demonstrated the important benefits that mobility adds to planetary exploration. Very soon, mission requirements will impose that planetary exploration rovers drive autonomously in unknown terrain. This will require an evolution of the methods and technologies currently used. This paper presents our approach to 3D terrain reconstruction from large sparse range data sets, and the data reduction achieved through decimation. The outdoor experimental results demonstrate the effectiveness of the reconstructed terrain model for different types of terrain. We also present a first attempt to classify the terrain based on the scans properties.
Architecture of a Predictive Maintenance Framework
Authors: Christin Groba, Sebastian Cech, Frank Rosenthal, Andreas Gossling
Venue: Proceedings of the 6th International Conference on Computer Information Systems and Industrial Management Applications (2007)

Predictive Maintenance is a promising maintenance strategy. However, existing solutions are isolated from enterprise systems and limited to specific applications. A predictive maintenance framework that integrates the diversity of existing techniques for equipment failure predictions and that incorporates data both from machine level and the upper enterprise level is still missing. We envision the development of a predictive maintenance framework that is characterized by a high degree of automation and the possibility to use state-of-the-art prediction methods. We attempt to create an open architecture that enables third-party suppliers to integrate their specialized prediction components into our framework. In this paper we analyze the requirements and introduce the initial architecture associated with such a predictive maintenance framework, which is being realized in a joint project with SAP Research.
On the performance of blind equalization using the second-order statistics
Authors: Yingbo Hua
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1996. on Conference Proceedings., 1996 IEEE International Conference - Volume 05 (1996)

Equalization based on blind channel estimation using the second-order statistics has a rapid convergence rate and is potentially attractive in digital wireless communications. The asymptotic behavior of this type of approach is investigated. In particular, the achievable lower bounds of the asymptotic mean-square error (MSE) are derived to serve as benchmarks for a class of blind equalization algorithms using second-order statistics. It is shown that the convergence rate of these equalizers suffers when channels are ill-conditioned. Applying this analysis to systems using antenna arrays, the performance gain of multiple receivers over single receiver is evaluated analytically.
Incorporating Clusters into Hybrid P2P Network
Authors: Ertao Lv, Zhenhua Duan, Jian-Jun Qi, Yang Cao, Zhuo Peng
Venue: Proceedings of the First International Conference on the Digital Society (2007)

Structured P2P network is popular nowadays. However, the network needs reorganized when the peers are joining or leaving. To reduce the performance degradation caused by the reorganizations, we proposed a two-layer hybrid P2P network (HP2P). The upper layer is Chord network and the lower layer is cluster in HP2P. In this paper, the cluster is described in detail. Peers are organized into clusters, and the network reorganizations are restricted within the clusters where a peer can join or leave. Besides, each cluster is also enhanced through some specific mechanisms such as Supernode, metadata redundancy and gossip flooding. Consequently, the two layers P2P become more robust. Further, the high efficiency of Distributed Hash Tables(DHTs) can be retained, and the churn caused by excessive node joining and leaving can be reduced.
Rethink the sync
Authors: Edmund B. Nightingale, Kaushik Veeraraghavan, Peter M. Chen, Jason Flinn
Venue: Proceedings of the 7th USENIX Symposium on Operating Systems Design and Implementation - Volume 7 (2006)

We introduce external synchrony, a new model for local file I/O that provides the reliability and simplicity of synchronous I/O, yet also closely approximates the performance of asynchronous I/O. An external observer cannot distinguish the output of a computer with an externally synchronous file system from the output of a computer with a synchronous file system. No application modification is required to use an externally synchronous file system: in fact, application developers can program to the simpler synchronous I/O abstraction and still receive excellent performance. We have implemented an externally synchronous file system for Linux, called xsyncfs. Xsyncfs provides the same durability and ordering guarantees as those provided by a synchronously mounted ext3 file system. Yet, even for I/O-intensive benchmarks, xsyncfs performance is within 7% of ext3 mounted asynchronously. Compared to ext3 mounted synchronously, xsyncfs is up to two orders of magnitude faster.
Ocean acoustic tomography structured covariance estimation
Authors: S. Bausson
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 2001. on IEEE International Conference - Volume 05 (2001)

Classic ocean acoustic tomography by Wiener inversion needs good estimates of the noise power affecting the errors between the in situ measurements of the travel times and their estimates obtained by reliable simulations. We investigate the maximum likelihood estimation of a structured covariance matrix, whose subspaces of interest are known, but whose associated powers are unknown. Using the ocean acoustic tomography constraints, we assume that the covariance is the sum of a full rank known matrix and an unknown component. We derive the maximum likelihood estimates for these noise powers and compute the Fisher information matrix to get insight into the geometric properties of the estimators. We verify with a realistic classic ocean acoustic tomography simulation the good quality of our noise power estimates.
Keeping a global technology working: a study into the social and technical dimensions of broadcast engineering in the Pacific Islands
Authors: W. Tibben
Venue: Proceedings of the Frontiers in Education Conference, 2001. on 31st Annual - Volume 01 (2001)

This paper is primarily concerned with exploring the technical and social dimensions of problem solving undertaken by technical staff in a Pacific Island radio station. Essentially, the paper addresses the question "what influence do physical and social contexts have on engineering knowledge development?". The paper notes that the concept of context is not given significant attention when looking to dominant philosophies of engineering. This stands in contrast to the importance accorded to context in development literature, particularly in. relation to technological knowledge. Using Macdonald's research into the role of information in innovation, the paper identifies a number of factors besides isolation that constrain access to problem solving information; namely, organisation size, poor commercial relationships, absence of interpersonal contacts with experts and unrealistic expectations of newly qualified engineers. This analysis points to a broader set of challenges than is often accepted in the training of engineers in small island economies: that is firstly of the sufficiency of theoretical knowledge and secondly, information being widely available and easy to transport by communication technologies. 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
Training peer-mentors to manage on-line class participation
Authors: A. D. Fontenot
Venue: Proceedings of the Frontiers in Education Conference, 2001. 31st Annual - Volume 02 (2001)

Although classes in all disciplines are being offered from almost every university and college on-line, the College of Engineering at Texas Tech University, feels that first year engineering courses offered on-line need more than just technology in order to keep them engaged in course content; they need support from faculty and from peers. This paper discusses the process of training peer-mentors to act as managers for on-line student support in the Introduction to Electrical Engineering and Computer Engineering course; how the selection process for peer-mentors plays a significant part in student, mentor, and faculty expectations; and how web technology allows the peer-mentors to develop skills beyond those found in traditional face-to-face peer-mentoring programs.
Towards System-level Optimization for High Performance Unified Threat Management
Authors: Yaxuan Qi, Baohua Yang, Bo Xu, Jun Li
Venue: Proceedings of the Third International Conference on Networking and Services (2007)

To build holistic protection against complex and blended network threats, multiple security features need to be integrated into unified security architecture, which requires in a Unified Threat Management (UTM). However, most existing UTMs operate by simply stringing together a number of security applications working independently without system level optimization that streamlines processing flow and leverages shared information and resources to reach high performance. In this paper, a generic framework is proposed to optimize the performance of UTMs at both algorithmic and architectural aspects by exploring the idea of Integrated Protocol Processing (IPP). The algorithm proposed in this paper improves overall protocol processing complexity of ACL and IDS from È(log(M)+log(N)) to È(log(M+N)) . Experiments on Intel IXP2850 network processor show that our scheme outperforms existing solutions with 30% increase of throughput.
Weighted myriad filters: a robust filtering framework derived from alpha-stable distributions
Authors: J. G. Gonzalez
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1996. on Conference Proceedings., 1996 IEEE International Conference - Volume 05 (1996)

We introduce a robust and nonlinear filtering framework: weighted myriad filtering. Much like the Gaussian assumption has motivated the development of linear filtering theory, the formulation of myriad filters is motivated by the statistical properties of /spl alpha/-stable processes. Weighted myriad filters have a solid theoretical basis, are inherently more powerful than weighted median filters, and are very general subsuming traditional linear FIR filters. The foundation of the proposed filtering algorithms lies in the definition of the sample myriad as the location estimate for a class of /spl alpha/-stable distributions. In turn, the myriad has been discovered as the location parameter estimated by the sample myriad. This paper addresses some theoretical properties of myriad filters. The superior performance of myriad filters in impulsive environments is illustrated in the problem of robust synchronization by means of a "myriad phase lock loop".
Some fallacies in the circuit analysis course
Authors: A. M. Davis
Venue: Proceedings of the 30th Annual Frontiers in Education - Volume 02 (2000)

This paper examines a number of common fallacies in the typical introductory circuit analysis text and offers a more logical, rigorous, and pedagogical approach for each. The majority of these fall within that segment of introductory circuit analysis dealing with active circuits and sub-circuits; more, however, can be found in each of the other major areas covered by such texts. It is hoped that this critique will spur a reexamination of the topics covered in introductory circuit analysis texts. 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