CUD@SAT: SAT solving on GPUs

The parallel computing power offered by graphic processing units (GPUs) has been recently exploited to support general purpose applications – by exploiting the availability of general API and the single-instruction multiple-thread-style parallelism present in several classes of problems (e.g. numerical simulations and matrix manipulations) – where relatively simple computations need to be applied to all items in large sets of data. This paper investigates the use of GPUs in parallelising a class of search problems, where the combinatorial nature leads to large parallel tasks and relatively less natural symmetries. Specifically, the investigation focuses on the well-known satisfiability testing (SAT) problem and on the use of the NVIDIA compute unified device architecture, one of the most popular platforms for GPU computing. The paper explores ways to identify strong sources of GPU-style parallelism from SAT solving. The paper describes experiments with different design choices and evaluates the results. The outcomes demonstrate the potential for this approach, leading to one order of magnitude of speedup using a simple NVIDIA platform.     

Interpretation of strokes in radial menus: The case of the KeyScretch text entry method

Most of the recently proposed text entry methods for touch screen devices are stroke-based: the traditional tapping interaction is being replaced with a more natural gesture, performed through a pointer (pen or finger) on a soft keyboard. These methods need an effective technique to interpret user strokes, in order to correctly obtain the text the user intends to enter. KeyScretch is a recent text entry method based on menu-augmented soft keyboards. The method introduces a new way of interacting with radial menus through compound strokes. In this paper we present the technology used for recognizing these strokes. In particular, the design of different recognizers is presented and their performances are compared. The evaluation shows that geometric stroke recognition techniques, associated to other calibrations, can significantly improve the accuracy achievable using a simple target-based method.     

PIGA (N,N-Di-n-butyl-5-chloro-2-(4-chlorophenyl)indol-3-ylglyoxylamide), a new mitochondrial benzodiazepine-receptor ligand, induces apoptosis in C6 glioma cells

Mitochondrial benzodiazepine-receptor (mBzR) ligands constitute a heterogeneous class of compounds that show a pleiotropic spectrum of effects within the cells, including the modulation of apoptosis. In this paper, a novel synthetic 2-phenylindol-3-ylglyoxylamide derivative, N,N-di-n-butyl-5-chloro-2-(4-chlorophenyl)indol-3-ylglyoxylamide (PIGA), which shows high affinity and selectivity for the mBzR, is demonstrated to induce apoptosis in rat C6 glioma cells. PIGA was able to dissipate mitochondrial transmembrane potential (DeltaPsim) and to cause a significant cytosolic accumulation of cytochrome c. Moreover, typical features of apoptotic cell death, such as caspase-3 activation and DNA fragmentation, were also detected in PIGA-treated cells. Our data expand the knowledge on mBzR ligand-mediated apoptosis and suggest PIGA as a novel proapoptotic compound with therapeutic potential against glial tumours, in which apoptosis resistance has been reported to be involved in carcinogenesis.     

The influence of construction errors in the law of motion of cam mechanismsEinfluss von konstruktiven fehlern auf die abtriebsbewegung von kurvengetrieben

In this study we illustrate the results of a systematic investigation to determine the influence which construction and assembly errors have on the law of motion obtained by means of cam mechanism, with particular regard to the law of acceleration.This investigation is based on the use of a kinematic analysis program described in a previous paper. In addition, the influence caused by simplifications on calculation sometimes adopted by the designers without adequate justifications is examined.Finally, the effect introduced by the angular velocity of the driver with a periodic irregularity is studied. The analysis carried out showed that the law of acceleration is not notably altered by the construction errors falling within usual tolerances. However, notable differences in the theoretical behaviour for both the case of insufficiently accurate design and the presence of periodic irregularities similar to those verified in mechanisms of this type are obtained.     

Heat Treatment Effect on Lignin and Carbohydrates in Corsican Pine Earlywood and Latewood Studied by PY–GC–MS Technique

Lignin-derived degradation products from non-treated (NT) and heat-treated (T) Corsican pine (Pinus nigra subsp. laricio) obtained by pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) were investigated, whereby the earlywood (EW) and latewood (LW) parts of the annual ring were considered separately. The data evaluation was done by principal component analysis (PCA) and the Kruskal–Wallis test. There are no differences in the pyrolysis products composition between EW and LW, but NT and T samples were discernible by PCA applied to Py–GC–MS data. Less phenols with longer chains (4-vinylguaiacol, and trans-isoeugenol) than those with shorter chains (guaiacol, 4-methylguaiacol) and an increase of anhydrosugar (AHS) were found among the pyrolysis products after heat treatment. These signs for autocondensation and side chain cleavages in the lignin during heat treatment were more evident in the EW than in the LW and for the crystallization of cellulose. A slight decrease of the carbohydrate/lignin ratio (C/L) after heat treatment indicates a greater degradation of carbohydrates compared to lignin. The relation of pyrolysis products of lignin and mechanical properties of wood was evaluated by regression analysis. An inverse correlation between short-chain phenols and MOE and a direct correlation between long-chain phenols and compression strength was found in case of NT wood, while a weak positive correlation could be observed between short-chain phenols and the density in T wood.     

Merit of hybrid EDFA/Raman amplification in fixed‐grid all‐optical network exploiting multirate transponders

The constant need to improve network capacity and reduce power consumption in current fixed‐grid WDM networks motivates researchers to find alternative solutions other than replacing the deployed equipment. One of the possible solutions is the use of hybrid EDFA/Raman amplifier, which improves signal‐to‐noise‐ratio in a point‐to‐point link. This work aims at quantifying, by means of a detailed power model, the effect of these novel ideas on the power consumption of the network, which is key to build a future green Internet. In particular, we consider the use of a randomly generated topology of 20 nodes to study the effect of hybrid amplification, fiber type, fiber span length, and sensitivity to average link length and average traffic per node. Results show that hybrid amplification in moderate pumping regime minimizes total network power consumption for networks made up of all 3 fiber types in particular for nonzero dispersion‐shifted fiber.     

On Nash equilibria for multicast transmissions in ad-hoc wireless networks

We study a multicast game in ad-hoc wireless networks in which a source sends the same message or service to a set of receiving stations via multi-hop communications and the overall transmission cost is divided among the receivers according to given cost sharing methods. We assume that each receiver gets a certain utility from the transmission and enjoys a benefit equal to the difference between his utility and the shared cost he is asked to pay. Assuming a selfish and rational behavior, each user is willing to receive the transmission if and only if his shared cost does not exceed his utility. Moreover, given the strategies of the other users, he wants to select a strategy of minimum shared cost. A Nash equilibrium is a solution in which no user can increase his benefit by choosing to adopt a different strategy. We consider the following reasonable cost sharing methods: egalitarian, semi-egalitarian next-hop-proportional, path-proportional, egalitarian-path-proportional and Shapley value. We prove that, while the first five cost sharing methods in general do not admit a Nash equilibrium, the Shapley value yields games always converging to a Nash equilibrium. We then turn our attention to the special case in which the receivers’ set R is part of the input (that is only the stations belonging to R have a positive utility which is set equal to infinity) and show that in such a case also the egalitarian and the egalitarian-path-proportional methods yield convergent games. In such a framework, we show that the price of anarchy is unbounded for the game yielded by the egalitarian method and provide matching upper and lower bounds for the price of anarchy of the other two convergent games with respect to two different global cost functions, that is the overall cost of the power assignment, that coincides with the sum of all the shared costs, and the maximum shared cost paid by the receivers. Finally, in all cases we show that finding the best Nash equilibrium is computationally intractable, that is NP-hard. Vittorio Bilò received the degree in Computer Science and the Ph.D. degree in Computer Science at the University of L’Aquila in 2001 and 2005 respectively. He is currently an assistant professor at the Department of Mathematics “Ennio De Giorgi” of the University of Lecce. His research interests include algorithms and computational complexity, communication problems in interconnection networks and game theoretical issues in non-cooperative networks. Michele Flammini received the degree in Computer Science at the University of L’Aquila in 1990 and the Ph.D. degree in Computer Science at the University of Rome “La Sapienza” in 1995. He is full professor at the Computer Science Department of the University of L’Aquila since March 2005. His research interests include algorithms and computational complexity, game theory, communication problems in interconnection networks and routing. He has authored and co-authored more than 70 papers in his fields of interest published in the most reputed international conferences and journals. Giovanna Melideo received the Laurea degree in computer science in 1997 from the University of L’Aquila (Italy) and the Ph.D. degree in computer engineering in 2001 from the University of Rome “La Sapienza”. From November 1999 to February 2000 she was visitor at IRISA/INRIA, University of Rennes 1, Rennes (France) in the ADP group. She was research fellow from June to October 2001 at the University of L’Aquila, where she is currently an assistant professor in the Computer Science Department. Her research interests include algorithms and complexity, algorithmic game theory, wireless networks, models for information integration and cooperative information systems, certification and security in e-service, distributed protocols and dependability. She has been a member of the scientific and organizing committee of the IFIP international workshop on Certification and Security in E-Services (CSES 2002), Montreal, Canada. Luca Moscardelli received the degree in Computer Science at the University of L’Aquila in 2004. He is currently a Ph.D. student in Computer Science at the University of L’Aquila. His current research interests include optimization problems in social and communication networks, and the analysis of the interaction between selfish agents in non-cooperative networks.     

Solid oxide fuel cell systems for distributed power generation and cogeneration

Solid oxide fuel cell (SOFC) is a promising technology for decentralized power generation and cogeneration. This technology has several advantages: the high electric efficiency, which can be theoretically improved through integration in power cycles; the low emissions; and the possibility of using a large variety of gaseous fuels.     

Reciprocal and variational principles in micropolar thermoelasticity of type II

In the present paper, in the context of thermoelasticity of type II (or thermoelasticity without energy dissipation), we establish reciprocal and variational principles of convolutional type for inhomogeneous and anisotropic micropolar thermoelastic materials with a center of symmetry. The results obtained in this work tend to generalize other variational principles (previously proved by the authors) not completely characterizing the initial-boundary value problem in concern.