Behavioural notions for elementary net systems

We study the relationships between a number of behavioural notions that have arisen in the theory of distributed computing. In order to sharpen the under-standing of these relationships we apply the chosen behavioural notions to a basic net-theoretic model of distributed systems called elementary net systems. The behavioural notions that are considered here are trace languages, non-sequential processes, unfoldings and event structures. The relationships between these notions are brought out in the process of establishing that for each elementary net system, the trace language representation of its behaviour agrees in a strong way with the event structure representation of its behaviour. M. Nielsen received a Master of Science degree in mathematics and computer science in 1973, and a Ph.D. degree in computer science in 1976 both from Aarhus University, Denmark. He has held academic positions at Department of Computer Science, Aarhus University, Denmark since 1976, and was visiting researcher at Computer Science Department, University of Edinburgh, U.K., 1977–79, and Computer Laboratory, Cambridge University, U.K., 1986. His research interest is in the theory of distributed computing. Grzegorz Rozenberg received a master of engineering degree from the Department of Electronics (section computers) of the Technical University of Warsaw in 1964 and a Ph.D. in mathematics from the Institute of Mathematics of the Polish Academy of Science in 1968. He has held acdeemic positions at the Institute of Mathematics of the Polish Academy of Science, the Department of Mathematics of Utrecht University, the Department of Computer Science at SUNY at Buffalo, and the Department of Mathematics of the University of Antwerp. He is currently Professor at the Department of Computer Science of Leiden University and Adjoint Professor at the Department of Computer Science of the University of Colorado at Boulder. His research interests include formal languages and automata theory, theory of graph transformations, and theory of concurrent systems. He is currently President of the European Association for Theoretical Computer Science (EATCS). P.S. Thiagarajan received the Bachelor of Technology degree from the Indian Institute of Technology, Madras, India in 1970. He was awarded the Ph.D. degree by Rice University, Houston Texas, U.S.A, in 1973. He has been a Research Associate at the Massachusetts Institute of Technology, Cambridge a Staff Scientist at the Geosellschaft für Mathematik und Datenverarbeitung, St. Augustin, a Lektor at Århus University, Århus and an Associate Professor at the Institute of Mathematical Sciences, Madras. He is currently a Professor at the School of Mathematics, SPIC Science Foundation, Madras. He research intest is in the theory of distributed computing.     

Cue exposure in moderation drinking: A comparison with cognitive–behavior therapy.

To date, the published controlled trials on exposure to alcohol cues have had an abstinence treatment goal. A modification of cue exposure (CE) for moderation drinking, which incorporated priming doses of alcohol, could train participants to stop drinking after 2 to 3 drinks. This study examined the effects of modified CE within sessions, combined with directed homework practice. Nondependent problem drinkers who requested a moderation drinking goal were randomly allocated to modified CE or standard cognitive-behavior therapy (CBT) for alcohol abuse. Both interventions were delivered in 6 90-min group sessions. Eighty-one percent of eligible participants completed treatment and follow-up assessment. Over 6 months, CE produced significantly greater reductions than CBT in participants' reports of drinking frequency and consumption on each occasion. No pretreatment variables significantly predicted outcome. The modified CE procedure appears viable for nondependent drinkers who want to adopt a moderate drinking goal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A modified ant-colony optimisation algorithm to minimise the completion time variance of jobs in flowshops

In this work, the flowshop scheduling problem is considered with the objective of minimising the completion-time variance (CTV) of jobs, and an Ant Colony Optimisation (ACO) algorithm is presented. Two implementations of the Modified Ant Colony Optimisation algorithm (MACO-I and MACO-II) are proposed to solve the permutation flowshop scheduling problem. The proposed ant-colony-algorithm implementations have been tested on 90 benchmark flowshop scheduling problems. The solutions yielded by the proposed MACO implementations are compared with various algorithms and with the best CTV of jobs reported in the literature. The proposed MACO implementations are found to perform very well in minimising the chosen performance measure.     

Effect of Nanoclay on the Impact Properties of Glass Fiber-Reinforced Polymer Composites

This paper presents the influence of nanoclay and E-glass fibre reinforcement on impact response in polymer composite laminates under low velocity impact loading conditions. Glass fibre reinforced epoxy/nanoclay composites were prepared by hand lay-up techniques. Morphological studies using SEM and XRD revealed that fully intercalation of nanoclay in epoxy system. The result showed that the energy absorption became more efficient and also increased by 21% for CSM fibre composites at the velocity of 4.42 m/s, when 3% nanoclay was added. The fracture surface of the nanocomposites was analyzed using the Scanning electron microscopy (SEM) to characterize the damage progression.     

Developing a country specific method for estimating nitrous oxide emissions from agricultural soils in Canada

Accurate estimates of nitrous oxide (N₂O) emissions from agricultural soils and management factors that influence emissions are necessary to capture the impact of mitigation measures and carry out life cycle analyses aimed at identifying best practices to reduce greenhouse gas emissions. We propose improvements to a country specific method for estimating N₂O emissions from agricultural soils in Canada based on a compilation of soil N₂O flux data from recent published literature. We provide a framework for the development of empirical models that could be applied in regions where similar data and information on N₂O emissions are available. The method considers spatial elements such as soil texture, topography and climate based on a quantitative empirical relationship between synthetic N-induced soil N₂O emission factor (EF) and growing season precipitation (P) {N₂OEF?=?e^{(0.00558P?7.7)}}. Emission factors vary from less than 0.0025 kg N₂O-N kg N^?1 in semi-arid regions of Canada to greater than 0.025 kg N₂O-N kg N^?1 in humid regions. This approach differentiates soil N₂O EFs based on management factors. Specifically, empirical ratio factors are applied for sources of N of 1.0, 0.84, and 0.28 for synthetic N, animal manure N and crop residue N, respectively. Crop type ratio factors where soil N₂O EFs from applied manure- and synthetic-N on perennial crops are approximately 19% of those on annual crops. This proposed approach improves the accuracy of the dominant factors that modulate N₂O emissions from N application to soils.

     

Reconfigurable Transceivers for Wireless Broadband Access Schemes

Though code division multiple access (CDMA) and orthogonal frequency division multiple access (OFDMA) are potential candidates for future broadband wireless access schemes, the requirements of the users may not be completely supported by a single communication system. Therefore, for easy connectivity and compatibility with the existing communication systems and to support various quality-of-service (QoS) requirements, systems with dynamic reconfigurability are inevitable. This article gives an overview of CDMA, OFDMA, and other block-based transmissions, and proposes a reconfigurable transceiver whose blocks can be configured in order to support any of the above air interfaces. The reconfigurable transceiver allows low-cost implementation of multiple air interfaces in a single terminal and achieves optimal QoS based on the available wireless networks.     

Elementary transition systems and refinement

Elementary transition systems are-in a strong categorical sense-the transition system version of a basic system model of net theory called elementary net systems. The structural notion of a region associated with elementary transition systems captures the intuitive idea of a local state as modelled by the conditions of an elementary net system. In this paper we equip elementary transition systems with a refinement operation over the local states (regions). We then show our operation satisfies a number of interesting properties. In particular, this operation supports compositional reasoning. It is very hard if not impossible to define a corresponding operation at the level of nets which enjoys similar properties. This is due to the concrete choice of conditions used to enforce intended behaviour. Thus our results show that the more abstract-but essentially equivalent-model of elementary transition systems is the appropriate framework for theoretical studies concerning refinement operations for elementary net systems.     

Computation and scaling of inductance gradients in electromagnetic launch systems

When a pulsed electric potential is applied to the terminals of a sliding electrical contact system, the armature translates under the influence of Lorentz forces caused by diffusing currents. The inductance gradient is conventionally used as a parameter to quantify the total Lorentz force acting on the armature and size the systems. The determination of the variation of the inductance gradient with system parameters such as the dimensions of the rails and armature, and the ramp rate of the applied potential is of interest in the design of sliding electrical contact systems with specified objectives. It is also useful in scaling results from laboratory to fieldable systems. The inductance gradient can be calculated with finite-element analyses using codes such as EMAP3D; this will be a time-consuming process. Semi-analytical formulations are possible for systems with simple and regular geometries such as rectangular sections. Solutions of the field diffusion equation can be expressed as a weighted sum of eigen functions characteristic of the geometry with imposed boundary conditions. A semi-analytical formulation based on eigen functions is presented here for computing and scaling inductance gradients of a sliding electrical contact system with rectangular rails and armatures. The effects of the dimensions of the rails and armatures, and the effect of the external ramp rate of the applied current on the inductance gradients are studied. The results are compared with available computational and experimental data.