Self-ignition and mechanisms of interaction of coal with oxygen at low temperatures. 1. Changes in the composition of coal heated at constant rate to 250 °C in air

The changes in weight, in elementary composition, in content of oxygen functional groups and in spin concentration of lignite, brown and black coal samples heated in a stream of humid air at a rate of 1 °C/min to various temperatures have been determined I.r. spectra of oxidized and non-oxidized brown coal are recorded and the yields of CO, CO₂ and H₂O were measured. The mixtures of low-molecular-weight hydrocarbons evolved before self-ignition were analysed by gas chromatography, and the temperatures of self-ignition were determined in an oxygen stream using a Leitz microscope. A region of coal oxidation was identified where the hydrogen content remained invariable or increased, indicating an interaction of coal with water in the presence of oxygen. For the next region the atomic ratio H/C of the overall gaseous product was found to be high (6 to 10). Self-ignition was found to occur in this region. The results permit coal oxidation to be considered as a redox process. The aromatic part of coal is believed to act as an oxidizing agent in the region where hydrogen is less affected by molecular oxygen.     

Adaptive neighborhood selection in peer-to-peer networks based on content similarity and reputation

To address the two most critical issues in P2P file-sharing systems: efficient information discovery and authentic data acquisition, we propose a Gnutella-like file-sharing protocol termed Adaptive Gnutella Protocol (AGP) that not only improves the querying efficiency in a P2P network but also enhances the quality of search results at the same time. The reputation scheme in the proposed AGP evaluates the credibility of peers based on their contributions to P2P services and subsequently clusters nodes together according to their reputation and shared content, essentially transforming the P2P overlay network into a topology with collaborative and reputed nodes as its core. By detecting malicious peers as well as free-riders and eventually pushing them to the edge of the overlay network, our AGP propagates search queries mainly within the core of the topology, accelerating the information discovery process. Furthermore, the clustering of nodes based on authentic and similar content in our AGP also improves the quality of search results. We have implemented the AGP with the PeerSim simulation engine and conducted thorough experiments on diverse network topologies and various mixtures of honest/dishonest nodes to demonstrate improvements in topology transformation, query efficiency, and search quality by our AGP.

Managing cohort movement of mobile sensors via GPS-free and compass-free node localization

A critical problem in mobile ad hoc wireless sensor networks is each node’s awareness of its position relative to the network. This problem is known as localization. In this paper, we introduce a variant of this problem, directional localization, where each node must be aware of both its position and orientation relative to its neighbors. Directional localization is relevant for applications that require uniform area coverage and coherent movement. Using global positioning systems for localization in large scale sensor networks may be impractical in enclosed spaces, and might not be cost effective. In addition, a set of pre-existing anchors with globally known positions may not always be available. In this context, we propose two distributed algorithms based on directional localization that facilitate the collaborative movement of nodes in a sensor network without the need for global positioning systems, seed nodes or a pre-existing infrastructure such as anchors with known positions. Our first algorithm, GPS-free Directed Localization (GDL) assumes the availability of a simple digital compass on each sensor node. We relax this requirement in our second algorithm termed GPS- and Compass-free Directed Localization (GCDL). Through experimentation, we demonstrate that our algorithms scale well for large numbers of nodes and provide convergent localization over time, despite errors introduced by motion actuators and distance measurements. In addition, we introduce mechanisms to preserve swarm formation during directed sensor network mobility. Our simulations confirm that, in a number of realistic scenarios, our algorithms provide for a mobile sensor network that preserves its formation over time, irrespective of speed and distance traveled. We also present our method to organize the sensor nodes in a polygonal geometric shape of our choice even in noisy environments, and investigate the possible uses of this approach in search-and-rescue type of missions.     

Validation of LAI and assessment of winter wheat status using spectral data and vegetation indices from SPOT VEGETATION and simulated PROBA-V images

Due to the information gap between the VEGETATION sensors and Sentinel-3 mission, the Belgian state decided to build a small satellite, Project for Onboard Autonomy-Vegetation (PROBA-V), to ensure the continuity of the data record for vegetation studies. In this study, simulated PROBA-V data generated by the Landsat Thematic Mapper (TM) were used to evaluate the potential of this mission to assess winter wheat status. The root mean square error (RMSE) of PROBA-V's leaf area index (LAI), which was generated using the exponential method and the interpolation method, is 0.33 and 0.96 for March 2011 and 1.40 and 3.33 for May 2011, respectively. Système Pour l'Observation de la Terre (SPOT) VEGETATION's LAI does not show a significant relationship with the reference LAI values except for the LAI values during the stem elongation 100% phenological stage generated using the exponential method (correlation coefficient, r = 0.91; p = 0.01). For the tillering and stem elongation 100% phenological stages, linear regression models for the fraction of absorbed photosynthetically active radiation (FAPAR) with PROBA-V's normalized difference vegetation index (NDVI) were developed (coefficient of determination, R ², of 0.94 and 0.88). Exponential models for LAI (R ² of 0.91 and 0.93) and fresh weight of above-ground biomass (AGBf) (R ² of 0.90 and 0.93) with PROBA-V's near-infrared (NIR) and visible and near-infrared bands (VNIR B2) were developed accordingly. The assessment of winter wheat status showed that the highest and the lowest values of PROBA-V's simulated data (SD), i.e. NDVI, normalized difference water index (NDWI), and LAI of Field 2 and Field 4, correspond to the ground-measured biometric parameters.     

Critical temperatures and pressures and high temperature vapour pressures of seven alcohols

Critical temperatures and pressures have been determined experimentally for the four lowest n-alcohols, 2-propanol, 2-butanol, and 2-methyl-1-propanol, and are given in the penultimate line of Table 3. The last line of Table 3 lists the weighted mean critical pressures, with the corresponding critical temperatures obtained from he vapour pressure equation. Comparison with the corresponding data from standard reference books reveals deviations from the experimental data in some [2, 4] and incorrect critical pressure for ethanol in all five reference books quoted in Table 3. In addition, vapour pressure data were obtained for the same alcohols in the temperature range approaching the critical point. The measurements are reproduced by the simplified Clausius-Clapeyron equation with the constants and standard deviation given in Table 2.     

Algebraic integer architecture with minimum adder count for the 2-D Daubechies 4-tap filters banks

A multiplierless architecture based on algebraic integer representation for computing the Daubechies 4-tap wavelet transform for 1-D/2-D signal processing is proposed. This architecture improves on previous designs in a sense that it minimizes the number of parallel 2-input adder circuits. The algorithm was achieved using numerical optimization based o exhaustive search over the algebraic integer representation. The proposed architecture furnishes exact computation up to the final reconstruction step, which is the operation that maps the exactly computed filtered results from algebraic integer representation to fixed-point. Compared to Madishetty et al. (IEEE Trans Circuits Syst I (Accepted, In Press), 2012a), this architecture shows a reduction of \(10\cdot n-3\) adder circuits, where \(n\) is the number of wavelet decomposition levels. Standard \(512\times 512\) images Mandrill, Lena, and Cameraman were submitted to digital realizations of both proposed algebraic integer based as well as fixed-point schemes, leading to quantifiable comparisons. The design is physically implemented for a 4-level 2-D decomposition using a Xilinx Virtex-6 vcx240t-1ff1156 FPGA device operating at up to a maximum clock frequency of 263.15 MHz. The FPGA implementation is tested using hardware co-simulation using an ML605 board with clock of 100 MHz. A 45 nm CMOS synthesis shows improved clock frequency of better than 500 MHz for a supply voltage of 1.1 V.     

An Efficient Architecture for a Lifted 2D Biorthogonal DWT

This paper presents a new algorithm for a 2D non-separable lifted bi-orthogonal wavelet transform. The algorithm is derived by factoring complementary pairs of wavelet transform 2D filters. The results are efficient architectures for real time signal processing, which do not require transpose memory for the 2D processing of data. The proposed architecture exploits in place implementation, inherit from the algorithm, and can take advantage of both vertical and horizontal parallelism in the direct implementation. The processing in our architecture is scheduled by carefully pipelining the lifted steps, which allows for up to four times faster processing than the direct implementation. The proposed architecture operates at high speed, consumes low power and has reduced computational complexity as compared to previously published filter and lifted based bi-orthogonal wavelet architectures.M. Alam (Student) is currently M.Sc. student in the Department of Electrical and Computer Engineering at University of Calgary. His research interest includes VLSI signal processing. He is recipient of iCORE International Graduate Scholarship.Wael Badawy (Ph.D. 00, M.Sc 98, 97; B.Sc. 94) is an associate professor in the Department of Electrical and Computer Engineering. He holds an adjunct professor in the Department of Mechanical Engineering, University of Alberta.Dr. Badawys research interests are in the areas of: Microelectronics, VLSI architectures for video applications with low-bit rate applications, digital video processing, low power design methodologies, and VLSI prototyping. His research involves designing new models, techniques, algorithms, architectures and low power prototype for novel system and consumer products. Dr. Badawy authored and co-authored more than 100 peer reviewed Journal and Conference papers and about 30 technical reports. He is the Guest Editor for the special issue on System on Chip for Real-Time Applications in the Canadian Journal on Electrical and Computer Engineering, the Technical Chair for the 2002 International Workshop on SoC for real-time applications, and a technical reviewer in several IEEE journals and conferences. He is currently a member of the IEEE-CAS Technical Committee on Communication. Dr. Badawy was honored with the 2002 Petro Canada Young Innovator Award, 2001 Micralyne Microsystems Design Award and the 1998 Upsilon Pi Epsilon Honor Society and IEEE Computer Society Award for Academic Excellence in Computer Disciplines. He is currently the Chairman of the Canadian Advisor Committee (CAC) and Head of the Canadian Delegation on ISO/IEC/JTC1/SC6 Telecommunications and Information Exchange Between Systems. Member, The Canadian Advisory Committee for the Standards Council of Canada-Subcommittee 29: Coding of Audio, Picture Multimedia and Hypermedia Information, and Canadian Delegate, The ISO/IEC MPEG standard committee. He is a voting Member on the VSI Alliance. He is also the Chair of the IEEE-Southern Alberta Society-Computer Chapter.Vassil S. Dimitrov was born in Plovdiv, Bulgaria, in 1964. He received his Ph.D. degree in mathematics in 1995 from the Mathematical Institute of the Bulgarian Academy of Sciences. Since then, he has spent two years as a postdocral fellow at the VLSI Research Group, University of Windsor, Canada, one year as a research scientist at the Reliable Software Technology Corporation, Virginia, USA, one year as a chief research scientist at the Signal Processing and Computer Technology Laboratory, Helsinki University of Technology, Finland, and one year as an Associate Professor at the University of Windsor, Canada. Since July 2001 he has held the position of Associate Professor at the Department of Electrical and Computer Engineering, University of Calgary, Canada. His main interests are in the area of number theoretic algorithms, computational complexity, cryptography, optimization theory, fast algorithms for digital signal processing and related topics. Dr. Dimitrov is a member of the New York Academy of Sciences.Graham Jullien (Fellow IEEE) was educated in the United Kingdom, receiving degrees, in Electrical Engineering, from the Universities of Loughborough, Birmingham and Aston (Ph.D., 1969). He was a student engineer and data processing engineer at English Electric Computers, UK, from 1961 to 1966, and a visiting senior research engineer at the Central Research Laboratories of EMI Ltd., UK, from 1975 to 1976. From 1969 until 2000 he was with the Department of Electrical and Computer Engineering at the University of Windsor, Ontario, Canada, where he held the rank of University Professor and was the Director of the VLSI Research Group. Since January 2001, he has been with the Department of Electrical and Computer Engineering at the University of Calgary, where he holds the iCORE Research Chair in Advanced Technology Information Processing Systems. He is a member of the Board of Directors of the Canadian Microelectronics Corporation (CMC) and is a member of the Steering Committee and Board of Directors of the Micronet Network of Centres of Excellence. He has published widely in the fields of Digital Signal Processing, Computer Arithmetic, Neural Networks and VLSI Systems, and teaches courses in related areas. He has served on the technical committees of many international conferences; he currently serves on the Editorial Board of the Journal of VLSI Signal Processing; and is a past Associate Editor of the IEEE Transactions on Computers. He hosted and was program co-chair of the 11th IEEE Symposium on Computer Arithmetic, was program chair for the 8th Great Lakes Symposium on VLSI, and was the technical program chair for the 1999 Asilomar Conference on Signals, Systems and Computers. He is general chair for the 2003 Asilomar Conference and general co-chair of the International Workshop on System-on-Chip for Real-Time Systems, Calgary, Alberta 2003.     

An energy conservation approach to adsorbate-induced surface stress and the extraction of binding energy using nanomechanics

Surface stress induced by molecular adsorption in three different binding processes has been studied experimentally using a microcantilever sensor. A comprehensive free-energy analysis based on an energy conservation approach is proposed to explain the experimental observations. We show that when guest molecules bind to atoms/molecules on a microcantilever surface, the released binding energy is retained in the host surface, leading to a metastable state where the excess energy on the surface is manifested as an increase in surface stress leading to the bending of the microcantilever. The released binding energy appears to be almost exclusively channeled to the surface energy, and energy distribution to other channels, including heat, appears to be inactive for this micromechanical system. When this excess surface energy is released, the microcantilever relaxes back to the original state, and the relaxation time depends on the particular binding process involved. Such vapor phase experiments were conducted for three binding processes: physisorption, hydrogen bonding, and chemisorption. Binding energies for these three processes were also estimated.     

Rigorous modeling of high-speed semiconductor devices

We present a review of industrial heterostructure devices based on SiGe/Si and III–V compound semiconductors analyzed by means of numerical simulation. A comparison of device simulators and current transport models is given and critical modeling issues are addressed. Results from two-dimensional hydrodynamic analyses of heterojunction bipolar transistors (HBTs) are presented in good agreement with measured data. The examples are chosen to demonstrate technologically relevant issues which can be addressed by device simulation.