ppxscal/embedding_network huggingface dataset:
Mechanized metatheory model-checking
Authors: James Cheney, Alberto Momigliano
Venue: Proceedings of the 9th ACM SIGPLAN international conference on Principles and practice of declarative programming (2007)

The problem of mechanically formalizing and proving metatheoretic properties of programming language calculi, type systems, operational semantics, and related formal systems has received considerable attention recently. However, the dual problem of searching for errors in such formalizations has received comparatively little attention. In this paper, we consider the problem of bounded model-checking for metatheoretic properties of formal systems specified using nominal logic. In contrast to the current state of the art for metatheory verification, our approach is fully automatic, does not require expertise in theorem proving on the part of the user, and produces counterexamples in the case that a flaw is detected. We present two implementations of this technique, one based on negation-as-failure and one based on negation elimination, along with experimental results showing that these techniques are fast enough to be used interactively to debug systems as they are developed.
Digital oscillators over finite fields
Authors: A. Orailoglu
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1996. on Conference Proceedings., 1996 IEEE International Conference - Volume 06 (1996)

This paper shows how the error-free computation properties of finite fields can be used to eliminate aperiodicity and SNR degradation problems in digital oscillators. Galois fields are used to eliminate representation and truncation errors in the values of sinusoid samples. Theorems are presented that characterize the fields which admit all operands necessary for a given phase resolution. Two oscillator architectures (exponential feedback and direct form) are presented and various design issues associated with each are discussed. It is also shown how field arithmetic can be replaced by arithmetic in the direct product ring associated with a set of specially chosen small fields. This is important in high-speed applications where the loop delay must be minimized. We also present analytical estimates of clocking frequency, latency, phase and frequency resolution, along with an example design in an Altera 7256 CPLD.
Working Set Based Scheduling in Time Warp Simulations
Authors: Malolan Chetlur, Philip A. Wilsey
Venue: Proceedings of the 40th Annual Simulation Symposium (2007)

This paper presents a new scheduling mechanism to choose and process the next input event from the event-set of simulation objects in a Logical Process (LP). Events are prioritized based on a simulation object's working set. Working set of a simulation object is analogous to working set defined in virtual memory, and consists of input and output events referenced in the recent past (without time-faults). The simulation kernel exploits the causality framework to determine the working set size of a simulation object. In addition, the scheduler favors events that are within the estimated working set size. This working set based scheduling mechanism shows a performance improvement in the order or 10%-15%. This technique also improves the overall efficiency and memory utilization.
Clustering and sharing incentives in BitTorrent systems
Authors: Arnaud Legout, Nikitas Liogkas, Eddie Kohler, Lixia Zhang
Venue: Proceedings of the 2007 ACM SIGMETRICS international conference on Measurement and modeling of computer systems (2007)

Peer-to-peer protocols play an increasingly instrumental role in Internet content distribution. It is therefore important to gain a complete understanding of how these protocols behave in practice and how their operating parameters affect overall system performance. This paper presents the first detailed experimental investigation of the peer selection strategy in the popular BitTorrent protocol. By observing more than 40 nodes in instrumented private torrents, we validate three protocol properties that, though believed to hold, have not been previously demonstrated experimentally: the clustering of similar-bandwidth peers, the effectiveness of BitTorrent's sharing incentives, and the peers' high uplink utilization. In addition, we observe that BitTorrent's modified choking algorithmin seed state provides uniform service to all peers, and that an underprovisioned initial seed leads to absence of peer clustering and less effective sharing incentives. Based on our results, we provide guidelines for seed provisioning by content providers, and discuss a tracker protocol extension that addresses an identified limitation of the protocol.
The Application of Users' Collective Experience for Crafting Suitable Search Engine Query Recommendations
Authors: Faezeh Ensan, Ebrahim Bagheri, Mohsen Kahani
Venue: Proceedings of the Fifth Annual Conference on Communication Networks and Services Research (2007)

Search engines have turned into one of the most important services of the Web that are frequently visited by any user. They assist their users in finding appropriate information. Among the many challenging issues in the design of Web search engines that is mostly related to the design of an adaptive interface is recommending suitable query phrases to the end-users. This has two major benefits: firstly the users can more easily interact with the Web search engine and secondly get hints on what is more apt to look for in cases where they may not have any clue. In this paper, we propose a graph based query recommendation algorithm that sequentially recommends query terms to its users. The most important notion behind the design of the algorithm is that the past behavior of previous users of a search engine is mined and a multi-segmented graph is built. Recommendation is made based on the relative similarity of query terms, their frequency and conceptual closeness in the graph.
Gyrokinetic simulation of micro-turbulence in magnetically confined plasmas
Authors: Nathan Joiner, Akira Hirose, William Dorland
Venue: Proceedings of the 21st International Symposium on High Performance Computing Systems and Applications (2007)

Small scale turbulence in toroidal magnetic fusion experiments (Tokamaks) causes the rapid loss of heat from the plasma. This is of great importance since it limits the fusion performance of proposed reactor concepts. Electron Temperature Gradient driven (ETG) modes have been proposed as a source of anomalous electron thermal loses in tokamaks. It is widely acknowledged that the electrostatic potential in ETG turbulence can develop into radially elongated structures known as streamers. Understanding the conditions that permit streamers to produce experimentally significant transport is a topic of great interest. Analysis of the ETG mode at long wavelengths where both the ions and electrons are adiabatic (have a Boltzmann response) show that the ETG mode is inherently electromagnetic. Mixing length estimates of the thermal transport coefficient in this regime peak at collisionless skin-depth scales, providing a possible â (the ratio of plasma pressure to magnetic pressure) dependence of the resulting transport. Preliminary nonlinear flux-tube simulations of the electromagnetic ETG mode produce large transport from the magnetic nonlinearity, while streamers in the electrostatic potential are still formed.
High performance explicit force control for finger interaction haptic interface
Authors: S. Marcheschi, F. Salsedo, M. Fontana, F. Tarri, O. Portillo-Rodriguez, M. Bergamasco
Venue: Proceedings of the Second Joint EuroHaptics Conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems (2007)

The requirements for a high performance Haptic Interface (HI) can arise from demanding VR applications such as the marketing on line of novel textiles or garments. Aiming at the improvement of the performance of the device, the integration of an explicit force control (i.e. a control making use of force measurement) on a HI, originally conceived for open loop control, may prove to be very challenging from the system stability point of view. This paper proposes a methodology for the dimensioning of a motion based explicit force control on the basis of the dynamic parameters of the plant (HI + human). The methodology highlights how the design solutions generally adopted for HIs intended for open loop force control can hinder the stability of the system when integrated with a closed loop force control.
Blind ISI cancellation by anchoring an arbitrary impulse response coefficient of channels
Authors: Jie Zhu
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 2000. on IEEE International Conference - Volume 05 (2000)

An algorithm for blind ISI cancellation in multi-user systems is developed in this paper. By minimizing the distance between the output of a filter and a reference signal with different time delay for two filters, the output of one filter turns out to be exactly equal to the ISI component of the output of the other filter. The difference between the output of these filters is the ISI-free estimate of the signal. With an appropriate selection of the time delay introduced for the reference signal, any coefficient of the channel impulse response which determines the scale of ISI-free estimate, can be anchored accordingly. Computer simulation has been conducted to illustrate the performance of this new method.
Case-based instruction on the web for teaching software project management
Authors: Pantelis M. Papadopoulos, Stavros N. Demetriadis, Ioannis G. Stamelos
Venue: Proceedings of the 12th annual SIGCSE conference on Innovation and technology in computer science education (2007)

Software project management (SPM) is an ill-structured domain, where past experiences of project management can become valuable learning resources for novices. To support instruction in the domain, we have developed the eCASE-SPM Web environment, for engaging students in case-based instruction and help them develop SPM related problem solving skills. This work presents major design issues of the environment and initial research results regarding (a) a student-based evaluation, connecting also students' attitudes to their learning styles, and (b) the learning effectiveness of the environment, investigating the use of embedded question prompts as students' cognitive scaffolds. Results so far reveal interesting interactions between students' learning styles and their attitudes towards learning in the eCASE-SPM environment. Furthermore, there is strong indication that using question prompts may have beneficial effect on students' learning and problem solving abilities, although fading out of the scaffolding should be implemented to moderate students' workload.
Migrating SIP-Based Conversational Services to IPv6: Complications and Interworking with IPv4
Authors: Mohamed Boucadair, Yoann Noisette
Venue: Proceedings of the Second International Conference on Digital Telecommunications (2007)

This paper focuses on complications related to the introduction of IPv6 into Conversational Services architectures. This paper identifies, first, complications encountered when enabling such critical services upon IPv6 infrastructures; second, it sketches a set of migration scenarios that take into account operational Service Providers requirements and elaborates on some enhancements to be supported. Experimentation results are also provided to illustrate how call routing may be optimized so as to minimize the invocation of ALG and NAT-PT functions.
Laboratory for telecommunications software technologies at the faculty of electrical engineering and computing at Zagreb
Authors: M. Kunstic
Venue: Proceedings of the 28th Annual Frontiers in Education - Volume 03 (1998)

The laboratory for telecommunications software technologies is part of the Department of Telecommunications at the Faculty of Electrical Engineering and Computing at Zagreb. The basic purpose of this laboratory is education of undergraduate and postgraduate students at the authors' Department (especially within the course "Information, logic and languages") and investigation within the project COST 247-"Verification/Validation Of Communication Software By Formal Methods" in which their Department has been involved since 1995. The laboratory is equipped with the help of the Ericsson Nikola Tesla company, and it enables research of specification, verification, simulation and implementation problems, related to telecommunication software. The authors are especially focused on the problems of concurrency, parallelism, distributed control and processing, which are of great importance in the telecommunications area.
Attacking Recommender Systems: A Cost-Benefit Analysis
Authors: Neil J. Hurley, Michael P. O'Mahony, Guenole C. M. Silvestre
Venue: IEEE Intelligent Systems (2007)

Collaborative recommender systems are vulnerable to attacks that seek to manipulate recommendations made for target items. The authors examine such attacks from a cost perspective, focusing on the effect that attack size—in terms of the number of ratings inserted during an attack—has on attack success. They present a cost-benefit analysis that shows that attackers can realize profits, even when financial costs are imposed on the insertion of ratings.
Student orientation program: a guide for higher education in Lebanon
Authors: A. Feghali, M. F. Abi-Aad, M. E. Abou Jaoudeh, N. A. Aouad, E. N. Hobeika
Venue: Proceedings of the Frontiers in Education Conference, on 1995. Proceedings., 1995 - Volume 02 (1995)

The country of Lebanon lacks career orientation and student counseling at the high school and college freshman levels. In response to that need, we are developing in the Multimedia Center of the Faculty of Engineering and Architecture at the American University of Beirut (AUB) a multimedia software package that offers help to students seeking university education. We conducted a needs analysis using questionnaires on a stratified random sample of high school and freshman university students. The results were used to tailor the content and design of the program to student needs and their computer literacy level. The student orientation program (SOP) is trilingual-English, French and Arabic-package developed using Asymetrix Multimedia Toolbook to be shipped on a CD-ROM. Users will find information about all universities in Lebanon and the respective majors offered as well as brief descriptions of professional fields of study, and scholarships available in Lebanon. Moreover potential university students have the choice to solve typical real life problems related to the field of study under investigation. Among other options, they can view video clip interviews with professionals and academicians that could answer typical questions. Finally, SOP provides self-assessment to help students identify potential career paths and domains of study to make a better choice for their future. We intend to distribute this CD-ROM to high schools in Lebanon and the Middle East in an attempt to improve career guidance in the region.
Overriding of Access Control in XACML
Authors: Ja'far Alqatawna, Erik Rissanen, Babak Sadighi
Venue: Proceedings of the Eighth IEEE International Workshop on Policies for Distributed Systems and Networks (2007)

Most access control mechanisms focus on how to define the rights of users in a precise way to prevent any violation of the access control policy of an organization. However, in many cases it is hard to predefine all access needs, or even to express them in machine readable form. One example of such a situation is an emergency case which may not be predictable and would be hard to express as a machine readable condition. Discretionary overriding of access control is one way for handling such hard to define and unanticipated situations where availability is critical. The override mechanism gives the subject of the access control policy the possibility to override a denied decision, and if the subject should confirm the override, the access will be logged for special auditing. XACML, the eXtensible Access Control Markup Language, provides a standardized access control policy language for expressing access control policies. This paper introduces a discretionary overriding mechanism in XACML. We do so by means of XACML obligations and also define a general obligation combining mechanism.
Unconditional maximum likelihood approach for blind estimation of digital signals
Authors: B. Halder
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1996. on Conference Proceedings., 1996 IEEE International Conference - Volume 02 (1996)

In contrast to conventional array processing, in many applications, such as mobile communications, the concept of a parametric array manifold is ill defined. In mobile communications the loss of a well defined array manifold can be attributed to the complex propagation environment consisting of multiple local scatterers near the mobile and remote dominant scatterers, as well as other co-channel signals. In such applications, estimation methods developed in the conventional setting of array processing are of little use and blind estimation of the transmitted signals is of real importance. We present an unconditional maximum likelihood (UML) approach for blind estimation of multiple co-channel digital BPSK signals received by an antenna array, along with the array response matrix A. Based on the idea of fixed point iteration, an efficient algorithm is derived to obtain the UML estimate of A and the maximum a posteriori (MAP) estimates of the digital signals. Simulation results are presented to demonstrate the improved performance of the proposed UML method over the conventional conditional ML (CML) methods. An upper bound on the bit error rate is also presented.
Seismic Propagation from Activity in Tunnels
Authors: Stephen A. Ketcham, Jason R. McKenna, Roy J. Greenfield, Thomas S. Anderson
Venue: Proceedings of the HPCMP Users Group Conference (2006)

Dynamic mechanical activity in a tunnel can be measured as ground vibrations at offset distances. These signals can be processed in sensing algorithms for detection, location, and discrimination of the activity. The objective of this work is to demonstrate that seismic simulations can reveal the effect of the environment on seismic energy as it propagates from tunnels. Using massively parallel high-performance computers, the work applies a finite-difference solution to the equations of motion and isotropic stress-velocity for viscoelastic seismic propagation. Results from simulations in open, urban, and mountainous terrain reveal the nature of seismic waves as they propagate from tunnel-digging pulses and harmonic sources. Measures of relative energy and signal cross correlation provide maps that reveal locations of optimal sensing. We demonstrate applications of beam forming to monitor tunnel activity, and conclude that the simulation method produces realistic wave-field data for virtual trials of sensing algorithms.
Rapid Prototyping of Intrusion Detection Systems
Authors: Fabrice Kordon, Jean-Baptiste Voron, Liviu Iftode
Venue: Proceedings of the 18th IEEE/IFIP International Workshop on Rapid System Prototyping (2007)

Designing security softwares that evolve as quickly as threats is a truthful challenge. In addition, current software becomes increasingly more complex and difficult to handle even for security experts. Intrusion Detection Softwares (IDS) represent a solution that can alleviate these concerns. This paper proposes a framework to automatically build an effective online IDS which can check if the program's expected behavior is respected during the execution. The proposed framework extracts relevant information from the program's source code to build a dedicated IDS. We use the GCC compiler to produce the structure of our behavior's model and ensure the IDS is correct. Thanks to Petri nets, our framework allows program offline monitoring and simplifies the online monitoring development.
Tool Support for Architectural Decisions
Authors: Anton Jansen, Jan van der Ven, Paris Avgeriou, Dieter K. Hammer
Venue: Proceedings of the Sixth Working IEEE/IFIP Conference on Software Architecture (2007)

In contrast to software architecture models, architectural decisions are often not explicitly documented, and therefore eventually lost. This contributes to major problems such as high-cost system evolution, stakeholders miscommunication, and limited reusability of core system assets. An approach is outlined that systematically and semi-automatically documents architectural decisions and allows them to be effectively shared by the stakeholders. A first attempt is presented that partially implements the approach by binding architectural decisions, models and the system implementation. The approach is demonstrated with an example demonstrating its usefulness with regards to some industrial use cases.
GSM speech coding and speaker recognition
Authors: L. Besacier
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 2000. on IEEE International Conference - Volume 02 (2000)

This paper investigates the influence of GSM speech coding on text independent speaker recognition performance. The three existing GSM speech coder standards were considered. The whole TIMIT database was passed through these coders, obtaining three transcoded databases. In a first experiment, it was found that the use of GSM coding degrades significantly the identification and verification performance (performance in correspondence with the perceptual speech quality of each coder). In a second experiment, the features for the speaker recognition system were calculated directly from the information available in the encoded bit stream. It was found that a low LPC order in GSM coding is responsible for most performance degradations. By extracting the features directly from the encoded bit-stream, we also managed to obtain a speaker recognition system equivalent in performance to the original one which decodes and reanalyzes speech before performing recognition.
Cellular mobile: the generation game
Authors: D. Wisely
Venue: BT Technology Journal (2007)

Cellular mobile is at an important crossroads -- with the industry still in the process of attempting a transition from the dominant second generation services of voice and messaging, to data-based services such as music download and gaming. Third generation technology has rolled out slowly in Europe and has yet to make much of an impact on the market. Against this backdrop, the cellular industry is now moving towards defining fourth generation mobile for introduction in 2012---2015. The emergence of new, non-cellular systems, such as WiMAX and WLAN are confusing the timeline and evolution of cellular systems with a heated debate about what constitutes a `4G system'. In addition, some people view convergence as the next generation of mobile with less emphasis on raw connection speed and more on access to the same services over a range of access technologies and devices. In this paper we critically examine these and other views of fourth generation mobile (4G) and identify the key technological, standards-related and commercial issues that will drive the evolution of 4G over the next few years.
A Semi-open Queueing Network Approach to the Analysis of Patient Flow in Healthcare Systems
Authors: Haifeng Xie, Theirry Chaussalet, Mike Rees
Venue: Proceedings of the Twentieth IEEE International Symposium on Computer-Based Medical Systems (2007)

In this paper, we present a modelling framework for patient flow in a healthcare system using semi-open queueing network models, which introduces a total bed constraint, above which new patients will be refused admission. Hence this model provides a realistic representation of a real system. This approach enables us to have access to a range of established methods that deals with queueing network models. We demonstrate the usefulness of the model in the context of a geriatric department and show that hospital managers can use this model to gain better understanding of the dynamics of patient flow and to study potential long-term impacts of policy changes.