ppxscal/embedding_network huggingface dataset:
HQ replication: a hybrid quorum protocol for byzantine fault tolerance
Authors: James Cowling, Daniel Myers, Barbara Liskov, Rodrigo Rodrigues, Liuba Shrira
Venue: Proceedings of the 7th USENIX Symposium on Operating Systems Design and Implementation - Volume 7 (2006)

There are currently two approaches to providing Byzantine-fault-tolerant state machine replication: a replica-based approach, e.g., BFT, that uses communication between replicas to agree on a proposed ordering of requests, and a quorum-based approach, such as Q/U, in which clients contact replicas directly to optimistically execute operations. Both approaches have shortcomings: the quadratic cost of inter-replica communication is unnecessary when there is no contention, and Q/U requires a large number of replicas and performs poorly under contention. We present HQ, a hybrid Byzantine-fault-tolerant state machine replication protocol that overcomes these problems. HQ employs a lightweight quorum-based protocol when there is no contention, but uses BFT to resolve contention when it arises. Furthermore, HQ uses only 3f+1 replicas to tolerate f faults, providing optimal resilience to node failures. We implemented a prototype of HQ, and we compare its performance to BFT and Q/U analytically and experimentally. Additionally, in this work we use a new implementation of BFT designed to scale as the number of faults increases. Our results show that both HQ and our new implementation of BFT scale as f increases; additionally our hybrid approach of using BFT to handle contention works well.
Engagement in supporting new teachers: a role for computer-mediated communication in teacher learning within informal professional communities
Authors: James V. Wertsch
Venue:  (2006)

This study examines some reasons why computer-mediated communication (CMC) has not lived up to public expectations and outlines a conceptual and methodological framework for characterizing interaction of experienced and novice teachers in informal network-based professional learning electronic- or e-communities. The study addresses three key research questions: (1) What properties characterize CMC engagement in professional learning e-comrnunities? (2) Why are some CMC groups more engaging than others? (3) How might the communicative structures of network-based CMC enhance or constrain the development of e-communities, and in turn, be relevant for CMC engagement? I argue that integrating dialogic voices/utterances (Bakhtin, 1986) and using texts as "thinking device[s]" for generating new meanings (Lotman, 1990; Wertsch, 1991) are essential for effectively engaging practitioners. Using both qualitative and quantitative methods, longitudinal discourse data, questionnaires, and interview responses were collected from public school teachers' email communications and subjected to analyses from discourse analytic and ethnographic perspectives, resulting in a characterization of CMC engagement and a taxonomy of e-communities. Results suggest that CMC engagement plays an important role in evaluating the effectiveness of learning with larger e-communities. E-communities can be defined by CMC engagement in terms of discourse and structural aspects of interaction. Despite the infrequent high level CMC engagement, it proved to be a productive means for explaining the professional life of practitioners within informal professional e-communities. The culture established within the "High Engagement Communities" gives rise to dialogicality, using others' utterances as thinking devices, and reflective thinking from multiple perspectives. This, in turn, can help maintain sustained threads. Differences in engagement among participants based on experience level were also noted. These findings suggest that sustainable models of online professional development should be associated with deeper levels of collaborative learning through higher levels of engagement and reflection on pedagogy. Although a necessary variable, CMC engagement by itself is not sufficient to make generalizations about professional development. Additional attributes, namely the commitment of the participants, their high-quality participation, and social relationships must also be taken in consideration. Implications and recommendations were provided. Future research will be needed to determine the impact of teachers' online participation both on their own practices and students' achievement.
Particle swarm optimization for integer programming
Authors: E. C. Laskari, K. E. Parsopoulos, M. N. Vrahatis
Venue: Proceedings of the Evolutionary Computation on 2002. CEC '02. Proceedings of the 2002 Congress - Volume 02 (2002)

The investigation of the performance of the particle swarm optimization (PSO) method in integer programming problems, is the main theme of the present paper. Three variants of PSO are compared with the widely used branch and bound technique, on several integer programming test problems. Results indicate that PSO handles efficiently such problems, and in most cases it outperforms the branch and bound technique.
Floating-point L^2 -approximations to functions
Authors: Nicolas Brisebarre, Guillaume Hanrot
Venue: Proceedings of the 18th IEEE Symposium on Computer Arithmetic (2007)

In the present paper, we investigate the approximation of a function by a polynomial with floating-point coefficients; we are looking for the best approximation in the L2 sense. Finding a best polynomial L2-approximation with real coefficients is an easy exercise about orthogonal projections. However, truncating the coefficients to floating-point numbers, which is needed for further computations, makes the approximation way worse. Hence, we study the problem of computing best approximations under the constraint that coefficients are floating-point numbers. We show that the corresponding problem is NP-hard, by reduction to the CVP problem. We investigate the practical behaviour of exact and approximate algorithms for this problem. The conclusion is that it is possible in a short amount of time to obtain a relative or absolute best L^2 -approximation. The main applications are for large dimension, as a preliminary step of finding L-approximations and for functions with large variations, for which relative best approximation is by far more interesting than absolute.
Acoustic model and pronunciation adaptation in automatic speech recognition
Authors: Michael Scordilis
Venue:  (2006)

The general goal of this thesis is to improve the performance of state-of-the-art statistical automatic speech recognition (ASR) operating in real time conditions. Such operating environment dictates that the system adapts to acoustic and linguistic mismatch between the development and deployment conditions. In order for this to be practically possible the system will need to cope with sparse available new training data, and perform in real time with modest computational and memory usage. Towards this goal, this investigation proceeded within the framework of statistical speech recognition and focuses on two aspects of ASR: (a) statistical model adaptation and its extension to acoustic model adaptation and (b) pronunciation adaptation. The basic strategy is to adjust the parameters of the pre-trained system, based on the information from new data, to fit characteristics of the new environment. We explore the actually observed acoustic mismatch, pronunciation variations and changes in background/channel condition, and investigate their essential effects on real-time statistical speech recognition. Then, we propose new methods of online acoustic model adaptation and online pronunciation adaptation. Also we generalize the state-level joint pronunciation variation modeling together with acoustic adaptation. We propose a new online EM alternative for adaptive (GMM) training together with a new unsupervised adaptation algorithm, which can dramatically reduce both computation and memory needs at the expense of only slight performance degradation when compared to its supervised counterpart. The proposed online EM alternative can have more general applicability in statistical adaptive training and it is not restricted to GMM. The investigation continues into the modeling of pronunciation variations, in which we propose an adaptive method to model pronunciation variations by introducing an incremental decision tree. By coupling each pronunciation rewriting rule with an associated occurrence probability and the underlying acoustical model, the partial change and new pronunciation can both be modeled with greater flexibility and enhanced accurately. The analyzed results demonstrate the effectiveness of the proposed method.
Making Radio Frequency Identification Visible--A Watchdog Tag
Authors: Christian Metzger, Christian Florkemeier, Philippe Bourquin, Elgar Fleisch
Venue: Proceedings of the Fifth IEEE International Conference on Pervasive Computing and Communications Workshops (2007)

To address the privacy concerns associated with RFID, previous work proposed an approach, where RFID readers do not only broadcast commands to inventory tag populations, but also transmit meta-information that describe the ongoing data collection. It was argued that RFID readers should explicitly declare the scope and purpose of their tag data collection by making this meta-information available to consumers and regulators through a watchdog tag. In this paper, we present the prototype of such a watchdog tag that is capable of decoding and displaying the meta-information broadcasted over the RFID communication channel for the visual inspection by the user. The paper details the design and implementation with discrete components, but also discusses limitations and future improvements. Our watchdog tag operates reliably and therefore, it suggests potential to enhance one's control over the data collected by RFID readers.
Efficient static analysis of XML paths and types
Authors: Pierre Genevès, Nabil Layaïda, Alan Schmitt
Venue: ACM SIGPLAN Notices (2007)

We present an algorithm to solve XPath decision problems under regular tree type constraints and show its use to statically type-check XPath queries. To this end, we prove the decidability of a logic with converse for finite ordered trees whose time complexity is a simple exponential of the size of a formula. The logic corresponds to the alternation free modal μ-calculus without greatest fixpoint, restricted to finite trees, and where formulas are cycle-free. Our proof method is based on two auxiliary results. First, XML regular tree types and XPath expressions have a linear translation to cycle-free formulas. Second, the least and greatest fixpoints are equivalent for finite trees, hence the logic is closed under negation. Building on these results, we describe a practical, effective system for solving the satisfiability of a formula. The system has been experimented with some decision problems such as XPath emptiness, containment, overlap, and coverage, with or without type constraints. The benefit of the approach is that our system can be effectively used in static analyzers for programming languages manipulating both XPath expressions and XML type annotations (as input and output types).
Instrumentness for creativity mediation, materiality & metonymy
Authors: Olav W. Bertelsen, Morten Breinbjerg, Søren Pold
Venue: Proceedings of the 6th ACM SIGCHI conference on Creativity cognition (2007)

We introduce the concept instrumentness as a quality of human-computer interfaces. Instrumentness points to the way musical instruments are controlled and conceptualized through values such as virtuosity and playability, which are important for computer-mediated creative work supporting development in use beyond what is initially designed for. The paper performs a conceptual investigation into qualities in software interfaces that support creativity, supported by analysis of, and interviews with, musical composers. Instrumentness is explained through discussions of materiality and metonymy as central strategies for computer mediated creativity. The paper is contributing to an investigation of the aesthetics of use in relation to software, pointing to alternative values, differing from traditional usability, which are also relevant in creative work outside art and music composition.
CPLD-oriented design projects for the first course in digital systems
Authors: D. J. Ahlgren
Venue: Proceedings of the 28th Annual Frontiers in Education - Volume 03 (1998)

This paper reports on enhanced educational outcomes that have been achieved at Trinity College by introducing complex programmable logic devices (CPLDs) and the hardware description language VHDL in the first course in digital design. Using Altera's Max+Plus II package and concurrent engineering practices, a team of eight students implemented a fully operational four-bit "tiny" CPU as a three-week final design project. Such successes demonstrate that modern CAD tools and use of CPLDs encourage creativity and system-level thinking in a first course.
Applicability of Energy Efficient Coding Methodology to Address Signal Integrity in 3D NoC Fabrics
Authors: Partha Pratim Pande, Amlan Gangul, Brett Feero, Cristian Grecu
Venue: Proceedings of the 13th IEEE International On-Line Testing Symposium (2007)

Three dimensional (3D) Network on Chip (NoC) has attracted researchers' attention recently. 3D NoCs are capable of achieving better system throughput and lower latency compared to the corresponding 2D implementations. To fully exploit the performance benefits of 3D architectures, it is imperative to address signal integrity issues in the design phase and its implications on energy dissipation. In this work we show that by incorporating joint crosstalk avoidance and multiple error correction schemes it is possible to enhance the robustness and reduce the energy dissipation simultaneously for both the 3D and more conventional planar NoC architectures. The achievable energy savings in 3D NoCs is significantly more than that in 2D structures.
Investigating sampling and quantization using a digital storage oscilloscope
Authors: J. W. Pierre
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 2001. on IEEE International Conference - Volume 05 (2001)

The objective of this paper is to reinforce students' understanding of sampling through experimentation. The scope of this paper is very narrow, focusing on a single laboratory exercise for learning about sampling, which is a critically important topic for students to comprehend. The digital oscilloscope makes an ideal platform for studying sampling, aliasing, and quantization, because not only does the digital oscilloscope have a built in A/D converter and all the supporting electronics, but it has display capabilities in both the time and frequency domains. Additionally, students obtain a better understanding of test and measurement equipment such as the digital oscilloscope.
Aspectual Support for Specifying Requirements in Software Product Lines
Authors: Harvey Siy, Prasanna Aryal, Victor Winter, Mansour Zand
Venue: Proceedings of the Early Aspects at ICSE: Workshops in Aspect-Oriented Requirements Engineering and Architecture Design (2007)

We present an aspect-oriented requirements specification system for software product lines. We encapsulate non-functional concerns as a set of advices for transforming parameterized requirements to product-specific requirements. We apply our system to the Health Watcher case study to demonstrate our approach. We sort out system requirements, exception handling requirements (alternate flows) and non-functional requirements and represent them as aspects in our framework. We have implemented a prototype transformation tool which takes these aspects along with the basic functional requirements as input and produces a requirements document with all applicable aspects woven in.
A posteriori compliance control
Authors: Sandro Etalle, William H. Winsborough
Venue: Proceedings of the 12th ACM symposium on Access control models and technologies (2007)

While preventative policy enforcement mechanisms can provide theoretical guarantees that policy is correctly enforced, they have limitations in practice. They are inflexible when unanticipated circumstances arise, and most are either inflexible with respect to the policies they can enforce or incapable of continuing to enforce policies on data objects as they move from one system to another. In this paper we propose an approach to enforcing policies not by preventing unauthorized use, but rather by deterring it. We believe this approach is complementary to preventative policy enforcement. We call our approach APPLE for A-Posteriori PoLicy Enforcement. We introduce APPLE Core, a logical framework for using logs to verify that actions taken by the system were authorized. A trust management system is used to ensure that data objects are provided only to users operating on auditable systems who are subject to penalty should they be found in violation. This combination of audit and accountability provides a deterence that strongly encourages trustworthy behavior, thereby allowing a high level of assurance of end-to-end policy enforcement.
Improving wordspotting performance with artificially generated data
Authors: E. I. Chang, R. P. Lippmann
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1996. on Conference Proceedings., 1996 IEEE International Conference - Volume 01 (1996)

Lack of training data is a major problem that limits the performance of speech recognizers. Performance can often only be improved by expensive collection of data from many different talkers. This paper demonstrates that artificially transformed speech can increase the variability of training data and increase the performance of a wordspotter without additional expensive data collection. This approach was shown to be effective on a high-performance whole-word wordspotter on the Switchboard Credit Card database. The proposed approach used in combination with a discriminative training approach increased the figure of merit of the wordspotting system by 9.4% percentage points (62.5% to 71.9%). The increase in performance provided by artificially transforming speech was roughly equivalent to the increase that would have been provided by doubling the amount of training data. The performance of the wordspotter was also compared to that of human listeners who were able to achieve lower error rates because of improved consonant recognition.
Residual noise compensation for robust speech recognition in nonstationary noise
Authors: Kaisheng Yao
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 2000. on IEEE International Conference - Volume 02 (2000)

We present a model-based noise compensation algorithm for robust speech recognition in nonstationary noisy environments. The effect of noise is split into a stationary part, compensated by parallel model combination, and a time varying residual. The evolution of residual noise parameters is represented by a set of state space models. The state space models are updated by Kalman prediction and the sequential maximum likelihood algorithm. Prediction of residual noise parameters from different mixtures are fused, and the fused noise parameters are used to modify the linearized likelihood score of each mixture. Noise compensation proceeds in parallel with recognition. Experimental results demonstrate that the proposed algorithm improves recognition performance in highly nonstationary environments, compared with parallel model combination alone.
Designing for collaborative creative problem solving
Authors: Otmar Hilliges, Lucia Terrenghi, Sebastian Boring, David Kim, Hendrik Richter, Andreas Butz
Venue: Proceedings of the 6th ACM SIGCHI conference on Creativity cognition (2007)

Collaborative creativity is traditionally supported by formal techniques, such as brainstorming. These techniques improve the idea-generation process by creating group synergies, but also suffer from a number of negative effects. Current electronic tools to support collaborative creativity overcome some of these problems, but introduce new ones, by either losing the benefits of face-to-face communication or the immediacy of simultaneous contribution. Using an interactive environment as a test bed, we are investigating how collaborative creativity can be supported electronically while maintaining face-to-face communication. What are the design-factors influencing such a system? We have designed a brainstorming application that uses an interactive table and a large wall display, and compared the results of using it to traditional paper-based brainstorming in a user study with 30 participants. From the considerations that went into the design and the observations during the study we derive a number of design guidelines for collaborative systems in interactive environments.
Fault location via precise dynamic slicing
Authors: Rajiv Gupta
Venue:  (2006)

Developing automated techniques for identifying a fault candidate set (i.e., subset of executed statements that contains the faulty code responsible for the failure during a program run), can greatly reduce the effort of debugging. Over 15 years ago precise dynamic slicing was proposed to identify a fault candidate set as consisting of all executed statements that influence the computation of an incorrect value through a chain of data and/or control dependences. However, the challenge of making precise dynamic slicing practical has not been addressed. This dissertation addresses this challenge and makes precise dynamic slicing useful for debugging realistic applications. First, the cost of computing precise dynamic slices is greatly reduced. Second, innovative ways of using precise dynamic slicing are identified to produce small failure candidate sets. The key cause of high space and time cost of precise dynamic slicing is the very large size of dynamic dependence graphs that are constructed and traversed for computing dynamic slices. By developing a novel series of optimizations the size of the dynamic dependence graph is greatly reduced leading to a compact representation that can be rapidly traversed. Average space needed is reduced from 2 Gigabytes to 94 Megabytes for dynamic dependence graphs corresponding to executions with average lengths of 130 Million instructions. The precise dynamic slicing time is reduced from up to 20 minutes for a demand-driven algorithm to 16 seconds. A compression algorithm is developed to further reduce dependence graph sizes. The resulting representation achieves the space efficiency such that the dynamic execution history of executing a couple of billion instructions can be held in a Gigabyte of memory. To further scale precise dynamic slicing to longer program runs, a novel approach is proposed that uses checkpointing/logging to enable collection of dynamic history of only the relevant window of execution.Classical backward dynamic slicing can often produce fault candidate sets that contain thousands of statements making the task of identifying faulty code very time consuming for the programmer. Novel techniques are proposed to improve effectiveness of dynamic slicing for fault location. The merit of these techniques lies in identifying multiple forms of dynamic slices in a failed run and then intersecting them to produce smaller fault candidate sets. Using these techniques, the fault candidate set size corresponding to the backward dynamic slice is reduced by nearly a factor of 3. A fine-grained statistical pruning technique based on value profiles is also developed and this technique reduces the sizes of backward dynamic slices by a factor of 2.5. In conclusion, this dissertation greatly reduces the cost of precise dynamic slicing and presents techniques to improve its effectiveness for fault location.