ppxscal/embedding_network huggingface dataset:
MAC protocols using directional antennas in IEEE 802.11 based ad hoc networks
Authors: Young-Bae Ko, Jong-Mu Choi, Nitin H. Vaidya
Venue: Wireless Communications Mobile Computing (2008)

Using directional antennas can be beneficial for wireless ad hoc networks consisting of a collection of wireless hosts. The most important benefit includes a reduction of the radio interference. Thus, it can significantly increase the spatial reuse, thereby improving the network throughput. To best utilize directional antennas, a suitable Medium Access Control (MAC) protocol must be designed. Current MAC protocols, such as the IEEE 802.11 standard, do not benefit when using directional antennas, because these protocols have been designed for omnidirectional antennas. In this paper, we present modified MAC protocols suitable for 802.11 based ad hoc networks using directional antennas. Our comprehensive simulation results demonstrate the performance improvement obtained with the proposed protocols. Copyright &copy; 2007 John Wiley & Sons, Ltd.
An efficient runtime instruction block verification for secure embedded systems
Authors: Aleksandar Milenkovic, Milena Milenkovic, Emil Jovanov
Venue: Journal of Embedded Computing (2006)

Embedded system designers face a unique set of challenges in making their systems more secure, as these systems often have stringent resource constraints or must operate in harsh or physically insecure environments. One of the security issues that have recently drawn attention is software integrity, which ensures that the programs in the system have not been changed either by an accident or an attack. In this paper we propose an efficient hardware mechanism for runtime verification of software integrity using encrypted instruction block signatures. We introduce several variations of the basic mechanism, and give details of three techniques that are most suitable for embedded systems. Performance evaluation using selected MiBench, Mediabench, and Basicrypt benchmarks indicates that the considered techniques impose a relatively small performance overhead. The best overall technique has performance overhead in the range 0-8%, when protecting 128-byte instruction blocks with 16-byte signatures. With 64-byte instruction blocks, the overhead is in the range 0-15%; the average overhead with 8~KB cache is 1%. With additional investment in a signature cache, this overhead can be almost completely eliminated.
Communication solution for GPS based airport service vehicles navigation
Authors: Tomas Zelinka, Miroslav Svitek
Venue: Proceedings of the 2007 Euro American conference on Telematics and information systems (2007)

Communications solution represents one of the key parts of the Intelligent Transport system (ITS). Methodology of the communication system identification and configuration was studied within projects CaMNA1 and SRAUTVU2. Goal of project CaMNA is to improve airport over-ground traffic efficiency and security for all moving aircrafts as well as service vehicles. Requirements on the communications environment are quantified indirectly by telematic sub-system performance indicators, which are usually applied in the ITS area. Right selection and configuration of the appropriate communication solution are achievable, if "transformation matrix" between vectors of communications and telematic performance indicators is correctly identified. Basic principles of method are introduced. Application of the proposed methodology is demonstrated on the CaMNA communications system identification and its parameters settings. CaMNA vehicle unit is designed for special navigation services operated in specific lively airport area conditions. Positional data are obtained from all service vehicles equipped with GNSS (Global Navigation Satellite System) as well as from non-GNSS A-SMGCS (Advanced Surface Movement Guidance and Control System). These data are centrally processed and together with dispatcher's decisions are delivered to every active service vehicle. Results of the communication solution parameters tests processed within CaMNA pilot installation and relevant recommendations are presented as the last part of this paper.
Effective characterizations of tree logics
Authors: Mikolaj Bojanńzyk
Venue: Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2008)

A survey of effective characterizations of tree logics. If L is a logic, then an effective characterization for L is an algorithm, which inputs a tree automaton and replies if the recognized language can be defined by a formula in L. The logics L considered include path testable languages, frontier testable languages, fragments of Core XPath, and fragments of monadic second-order logic.
Verification Framework for Detecting Safety Violations in UML Statecharts
Authors: Chikmagalur Manjappa Prashanth, K. Chandrashekar Shet, Janees Elamkulam
Venue: Proceedings of the 2008 Second Asia International Conference on Modelling & Simulation (AMS) (2008)

The model based development is a widely accepted phenomenon to build dependable software. This has lead to development of tools which can generate deployable code from the model. Hence, ensuring the correctness of such models becomes extremely important. Model checking technique can be applied to detect specification violations in such models at the early stage of development life cycle. In practice, such validations are done using off-the-shelf model checkers. This technique though popular has a drawback that, model should be described in the native language of the model checker. In this paper, we propose a framework for the verification of the dynamic behavior of reactive systems modeled using UML (Unified Modeling Language) statechart diagrams. The model is translated to an intermediate representation by parsing the information embedded behind the UML statecharts, this intermediate representation is used for checking the safety violations. Verification framework proposed is scalable to complex systems.
Frequency domain based adaptive phase-lead controllers for single-phase inverters
Authors: Mohammadreza Rafiei
Venue: Proceedings of the 6th WSEAS International Conference on Systems Theory & Scientific Computation (2006)

In this paper novel adaptive control approaches for control of single-phase Current Regulated PWM (CRPWM) inverters are proposed. The optimal tracking feature that is tracking the reference signal with low phase and amplitude errors is one of the main goals in inverter systems. Conventional controllers such as Proportional-Integral (PI) controllers cannot guaranty satisfactory tracking capability for many applications. This paper presents frequency domain based adaptive mechanisms to mitigate the phase and gain errors while the inverter system is treated as a multivariable system. One strategy uses Band Pass Filters (BPF) with adjustable center frequencies tuned by a Neural Network system, and the other employs a fixed BPF plus an adjustable time delay. In the first, the filters are adjusted by a neural network based adaptive system for perfect tracking, whereas in the second strategy, the simpler one, a simple adjustable digital time delay removes the phase error of the overall system. The simulation results obtained through MATLAB/SIMULINK software show the successful operation of the proposed systems.
Splitting methods for non-autonomous linear systems
Authors: Sergio Blanes, Fernando Casas, Ander Murua
Venue: International Journal of Computer Mathematics (2007)

We present splitting methods for numerically solving a certain class of explicitly time-dependent linear differential equations. Starting from an efficient method for the autonomous case and making use of the formal solution obtained with the Magnus expansion, we show how to get the order conditions for the non-autonomous case. We also build a family of sixth-order integrators whose performance is clearly superior to previous splitting methods on several numerical examples.
Sensory and association cortex in time perception
Authors: Domenica Bueti, Bahador Bahrami, Vincent Walsh
Venue: Journal of Cognitive Neuroscience (2008)

The recent upsurge of interest in brain mechanisms of time perception is beginning to converge on some new starting points for investigating this long under studied aspect of our experience. In four experiments, we asked whether disruption of normal activity in human MT/V5 would interfere with temporal discrimination. Although clearly associated with both spatial and motion processing, MT/V5 has not yet been implicated in temporal processes. Following predictions from brain imaging studies that have shown the parietal cortex to be important in human time perception, we also asked whether disruption of either the left or right parietal cortex would interfere with time perception preferentially in the auditory or visual domain. The results show that the right posterior parietal cortex is important for timing of auditory and visual stimuli and that MT/V5 is necessary for timing only of visual events.
Fabrication and electrical characteristics of Schottky diode based on organic material
Authors: Ö. Güllü, Ş. Aydoğan, A. Türüt
Venue: Microelectronic Engineering (2008)

The current-voltage (I-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristics of Al/Orange G/n-Si/AuSb structure were investigated at room temperature. A modified Norde's function combined with conventional forward I-V method was used to extract the parameters including barrier height (BH) and the series resistance. The barrier height and series resistance obtained from Norde's function was compared with those from Cheung functions, and it was seen that there was a good agreement between series resistances from both methods. The C-V characteristics were performed at 10kHz and 500kHz frequencies, and C-f characteristics were performed 0.0V, +0.4V and -0.4V.
Sparse Bayesian nonparametric regression
Authors: François Caron, Arnaud Doucet
Venue: Proceedings of the 25th international conference on Machine learning (2008)

One of the most common problems in machine learning and statistics consists of estimating the mean response X&beta; from a vector of observations y assuming y = X&beta; + &epsilon; where X is known, &beta; is a vector of parameters of interest and &epsilon; a vector of stochastic errors. We are particularly interested here in the case where the dimension K of &beta; is much higher than the dimension of y. We propose some flexible Bayesian models which can yield sparse estimates of &beta;. We show that as K &rarr; &infin; these models are closely related to a class of L&eacute;vy processes. Simulations demonstrate that our models outperform significantly a range of popular alternatives.
Two stages of case-based reasoning - Integrating genetic algorithm with data mining mechanism
Authors: Heng-Li Yang, Cheng-Shu Wang
Venue: Expert Systems with Applications: An International Journal (2008)

Case-based reasoning (CBR) is a paradigm, concept and instinctive mechanism for problem solving. Recently, CBR has been widely integrated with some AI algorithms and applied to various kinds of problems. The ill-defined and unstructured problems are suitably solved by CBR. This research proposes a hybrid CBR mechanism including two stages. In stage I, the genetic algorithm is adopted to improve efficiency of case retrieving process. Compared to traditional CBR, the proposed mechanism could reduce about 14% case evaluations, but still achieved 90% satisfactory results. In stage II, the knowledge discovering and data mining (KDD) processes are implemented to produce the refined information from the retrieved cases. Because these retrieved cases and target problem satisfy similar or even same conditions, the outcome of KDD would be more valuable for reference. In addition to retrieved cases of stage I, the proposed mechanism provides direction and relevant knowledge for decision makers in their decision supporting and revising processes in stage II. The proposed CBR mechanism also deals with efficiency and outcome quality issues of traditional CBR.
Evaluation of linear spectral unmixing and ΔNBR for predicting post-fire recovery in a North American ponderosa pine forest
Authors: A. M. S. Smith, L. B. Lentile, A. T. Hudak, P. Morgan
Venue: International Journal of Remote Sensing (2007)

The Differenced Normalized Burn Ratio (ΔNBR) is widely used to map post-fire effects in North America from multispectral satellite imagery, but has not been rigorously validated across the great diversity in vegetation types. The importance of these maps to fire rehabilitation crews highlights the need for continued assessment of alternative remote sensing approaches. To meet this need, this study presents a first preliminary comparison of immediate post-fire char (black ash) fraction, as measured by linear spectral unmixing, and ΔNBR, with two quantitative one-year post-fire field measures indicative of canopy and sub-canopy conditions: % live tree and dry organic litter weight (gm-2). Image analysis was applied to Landsat 7 Enhanced Thematic Mapper (ETM+) imagery acquired both before and immediately following the 2000 Jasper Fire, South Dakota. Post-fire field analysis was conducted one-year post-fire. Although the immediate post-fire char fraction (r 2 = 0.56, SE = 28.03) and ΔNBR (r 2 = 0.55, SE = 29.69) measures produced similarly good predictions of the % live tree, the standard error in the prediction of litter weight with the char fraction method (r 2 = 0.55, SE = 4.78) was considerably lower than with ΔNBR (r 2 = 0.52, SE = 8.01). Although further research is clearly warranted to evaluate more field measures, in more fires, and across more fire regimes, the char fraction may be a viable approach to predict longer-term indicators of ecosystem recovery and may potentially act as a surrogate retrospective measure of the fire intensity.
Digital Wall: A Power-efficient Solution for Location-based Data Sharing
Authors: Jeffrey Junfeng Pan, Sinno Jialin Pan, Vincent Wenchen Zheng, Qiang Yang
Venue: Proceedings of the 2008 Sixth Annual IEEE International Conference on Pervasive Computing and Communications (2008)

With the proliferation of wireless and sensor techniques, data can be shared conveniently through the air. However, wireless communication is vulnerable since unauthorized machine may try to intrude a server without being physically connected. In this paper, we wish to control the communication between a wireless client and the infrastructure based on the client location. Our idea is toimplement a digital wall, which is a user-defined boundary so that access is allowed within the boundary and denied outside the boundary. To do this, we need to do accurate location estimation since the decision around the boundary line is critical. Furthermore, computational efficiency is also important since we need to reduce computation cost so as to save power energy. In this paper, we propose k-nearest-neighbor (KNN) based method to determine the location of a mobile client based on received signal strength (RSS) values. We further use information gain as a feature selection criterion to reduce the estimation time. We study how the performance may be affected when the controlled area is confined by physical or virtual walls. Experimental results show that we can well distinguish whether a client device is located within anexpected digital wall.
Approximations of Nash equilibria
Authors: G&#x00fc;l G&#x00fc;rkan, Jong-Shi Pang
Venue: Mathematical Programming: Series A and B (2008)

Inspired by previous works on approximations of optimization problems and recent papers on the approximation of Walrasian and Nash equilibria and on stochastic variational inequalities, the present paper investigates the approximation of Nash equilibria and clarifies the conditions required for the convergence of the approximate equilibria via a direct approach, a variational approach, and an optimization approach. Besides directly addressing the issue of convergence of Nash equilibria via approximation, our investigation leads to a deeper understanding of various notions of functional convergence and their interconnections; more importantly, the investigation yields improved conditions for convergence of the approximate Nash equilibria via the variational approach. An illustrative application of our results to the approximation of a Nash equilibrium in a competitive capacity expansion model under uncertainty is presented.
Application of logistic regression model in Rasch measurement to establish a performance index: a case study in audits on Malaysian institutions of higher learning
Authors: Razimah Abdullah, Rosmawati Abd Halim, Azami Zaharim, Rozeha A. Rashid, Mohd Saidfudin Masodi
Venue: Proceedings of the 12th WSEAS International Conference on Applied Mathematics (2007)

Performance measurement has traditionally been determined using historical data to establish the 'best fit line'. Measuring performance in an appropriate way is vital to ensure valid quality information can be generated for meaningful use. A matter of prime concern in organisational excellence is internal audit, a control mechanism against systems failures. This paper promulgate the attempt of a new approach in establishing a performance measurement based on the Plan-Execute-Report-Monitor (PERM) Model, in this case the Audit Performance index; APi. A perception survey was conducted on auditors from selected Malaysian Institution of Higher Learning (IHL). Data obtained is used to calculate the performance indicators; Dk and index which are closely connected with various emotional, cognitive and intentional components. Instead of the common use of simple means over several ordinal variables, Rasch Measurement 'logit unit' enable the construction of a linear scale, based on a set of survey items where the mean, xi is the probability of a successful audit hence; the APi index. Using Logistic Regression Model, it was found that the probabilistic model can help establish a theoretical basis for measuring such service performance and help IHL top management in improving their judgemental decision making. Rather than deterministic linear regression, the performance index established based on probabilistic model is more appropriate since the process outcome is a dependant variable; θ which is predictable within the limit of 0.0 to 1.0. Since the index is modelled using dimensions and attributes related to the audit process, the APi enables a more holistic and reliable evaluation of an audit process effectiveness, Ae; hence, the level of service effectiveness rendered.
Optimized reversible binary-coded decimal adders
Authors: Michael Kirkedal Thomsen, Robert Glück
Venue: Journal of Systems Architecture: the EUROMICRO Journal (2008)

Babu and Chowdhury [H.M.H. Babu, A.R. Chowdhury, Design of a compact reversible binary coded decimal adder circuit, Journal of Systems Architecture 52 (5) (2006) 272-282] recently proposed, in this journal, a reversible adder for binary-coded decimals. This paper corrects and optimizes their design. The optimized 1-decimal BCD full-adder, a 13x13 reversible logic circuit, is faster, and has lower circuit cost and less garbage bits. It can be used to build a fast reversible m-decimal BCD full-adder that has a delay of only m+17 low-power reversible CMOS gates. For a 32-decimal (128-bit) BCD addition, the circuit delay of 49 gates is significantly lower than is the number of bits used for the BCD representation. A complete set of reversible half- and full-adders for n-bit binary numbers and m-decimal BCD numbers is presented. The results show that special-purpose design pays off in reversible logic design by drastically reducing the number of garbage bits. Specialized designs benefit from support by reversible logic synthesis. All circuit components required for optimizing the original design could also be synthesized successfully by an implementation of an existing synthesis algorithm.
Disjoint clique cutsets in graphs without long holes
Authors: Elaine M. Eschen, Chính T. Hoàng, Mark D. T. Petrick, R. Sritharan
Venue: Journal of Graph Theory (2005)

A biclique cutset is a cutset that induces the disjoint union of two cliques. A hole is an induced cycle with at least five vertices. A graph is biclique separable if it has no holes and each induced subgraph that is not a clique contains a clique cutset or a biclique cutset. The class of biclique separable graphs contains several well-studied graph classes, including triangulated graphs. We prove that for the class of biclique separable graphs, the recognition problem, the vertex coloring problem, and the clique problem can be solved efficiently. Our algorithms also yield a proof that biclique separable graphs are perfect. Our coloring algorithm is actually more general and can be applied to graphs that can be decomposed via a special type of biclique cutset. Our algorithms are based on structural results on biclique separable graphs developed in this paper. &copy; 2005 Wiley Periodicals, Inc. J Graph Theory 48: 277&ndash;298, 2005
Dynamic multiagent probabilistic inference
Authors: Xiangdong An, Yang Xiang, Nick Cercone
Venue: International Journal of Approximate Reasoning (2008)

Cooperative multiagent probabilistic inference can be applied in areas such as building surveillance and complex system diagnosis to reason about the states of the distributed uncertain domains. In the static cases, multiply sectioned Bayesian networks (MSBNs) have provided a solution when interactions within each agent are structured and those among agents are limited. However, in the dynamic cases, the agents' inference will not guarantee exact posterior probabilities if each agent evolves separately using a single agent dynamic Bayesian network (DBN). Nevertheless, due to the discount of the past, we may not have to use the whole history of a domain to reason about its current state. In this paper, we propose to reason about the state of a distributed dynamic domain period by period using an MSBN. To reduce the influence of the ignored history on the posterior probabilities to a minimum, we propose to observe as many observable variables as possible in the modeled history. Due to the limitations of the problem domains, it could be very costly to observe all observable variables. We present a distributed algorithm to compute all observable variables that are relevant to our concerns. Experimental results on the relationship between the computational complexity and the length of the represented history, and effectiveness of the approach are presented.
An Early (1844) Key-Driven Adding Machine
Authors: Denis Roegel
Venue: IEEE Annals of the History of Computing (2008)

This article presents Jean-Baptiste Schwilguć's 1844 adding machine, which was equipped with a number of unique features, in particular with what was apparently the first numerical keyboard.
Long John Software and the Digital Jolly Roger
Authors: David Alan Grier
Venue: Computer (2008)

In unleashing our treasure ships of software bits and bytes upon the world, we have also opened it up to a new generation of pirates.