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21.
A simple mutual exclusion algorithm is presented that only uses nonatomic shared variables of bounded size, and that satisfies
bounded overtaking. When the shared variables behave atomically, it has the first-come-first-served property (FCFS). Nonatomic
access makes information vulnerable. The effects of this can be mitigated by minimizing the information and by spreading it
over more variables. The design approach adopted here begins with such mitigating efforts. These resulted in an algorithm
with a proof of correctness, first for atomic variables. This proof is then used as a blueprint for the simultaneous development
of the algorithm for nonatomic variables and its proof. Mutual exclusion is proved by means of invariants. Bounded overtaking
and liveness under weak fairness are proved with invariants and variant functions. Liveness under weak fairness is formalized
and proved in a set-theoretic version of temporal logic. All these assertions are verified with the proof assistant PVS. We
heavily rely on the possibility offered by a proof assistant like PVS to reuse proofs developed for one context in a different
context. 相似文献
22.
Cole JN Henningham A Gillen CM Ramachandran V Walker MJ 《Proteomics. Clinical applications》2008,2(3):387-410
Gram-positive streptococci are non-motile, chain-forming bacteria commonly found in the normal oral and bowel flora of warm-blooded animals. Over the past decade, a proteomic approach combining 2-DE and MS has been used to systematically map the cellular, surface-associated and secreted proteins of human pathogenic streptococcal species. The public availability of complete streptococcal genomic sequences and the amalgamation of proteomic, genomic and bioinformatic technologies have recently facilitated the identification of novel streptococcal vaccine candidate antigens and therapeutic agents. The objective of this review is to examine the constituents of the streptococcal cell wall and secreted proteome, the mechanisms of transport of surface and secreted proteins, and describe the current methodologies employed for the identification of novel surface-displayed proteins and potential vaccine antigens. 相似文献
23.
We review the literature on long memory ARFIMA and GARMA models andintroduce a new efficient estimator for GARMA models, which we show to berobust. Next we conduct a Monte Carlo study to demonstate the power of theDickie–Fuller test when the data are generated from a stationary GARMAprocess. We conclude with a brief discussion of cointegration in the contextof GARMA models with an application to international interest rates. 相似文献
24.
Probabilistic belief contraction has been a much neglected topic in the field of probabilistic reasoning. This is due to the difficulty in establishing a reasonable reversal of the effect of Bayesian conditionalization on a probabilistic distribution. We show that indifferent contraction, a solution proposed by Ramer to this problem through a judicious use of the principle of maximum entropy, is a probabilistic version of a full meet contraction. We then propose variations of indifferent contraction, using both the Shannon entropy measure as well as the Hartley entropy measure, with an aim to avoid excessive loss of beliefs that full meet contraction entails. 相似文献
25.
Ravi Gummadi Anupam Khulbe Aravind Kalavagattu Sanil Salvi Subbarao Kambhampati 《Journal of Intelligent Information Systems》2012,38(3):575-599
Many web databases can be seen as providing partial and overlapping information about entities in the world. To answer queries effectively, we need to integrate the information about the individual entities that are fragmented over multiple sources. At first blush this is just the inverse of traditional database normalization problem—rather than go from a universal relation to normalized tables, we want to reconstruct the universal relation given the tables (sources). The standard way of reconstructing the entities will involve joining the tables. Unfortunately, because of the autonomous and decentralized way in which the sources are populated, they often do not have Primary Key–Foreign Key relations. While tables may share attributes, naive joins over these shared attributes can result in reconstruction of many spurious entities thus seriously compromising precision. Our system, SmartInt is aimed at addressing the problem of data integration in such scenarios. Given a query, our system uses the Approximate Functional Dependencies (AFDs) to piece together a tree of relevant tables to answer it. The result tuples produced by our system are able to strike a favorable balance between precision and recall. 相似文献
26.
Aravind Dasari Zhong-Zhen Yu Mingshu Yang Qing-Xin Zhang Xiao-Lin Xie Yiu-Wing Mai 《Composites Science and Technology》2006,66(16):3097-3114
The primary aim of this paper is to provide an insight on the effect of the location of organoclay on the micro- and nano-scale deformation processes in melt-compounded nylon 66/organoclay/SEBS-g-MA ternary nanocomposites prepared by different blending sequences. In addition, the deformation processes of the ternary nanocomposites were compared to the binary nanocomposites (nylon 66/organoclay and nylon 66/SEBS-g-MA) and neat nylon 66. The incorporation of SEBS-g-MA particles toughened nylon 66 markedly; but the flexural modulus and strength were both reduced. Conversely, the use of organoclay increased the modulus but decreased the fracture toughness of nylon 66. Nylon 66/SEBS-g-MA/organoclay ternary nanocomposites exhibited balanced elastic stiffness and toughness. Stress-whitening studies of the fracture surfaces in terms of gray level were also performed and an attempt was made to correlate the optical reflectivity characteristics with fracture toughness. It was concluded that the capability of SEBS-g-MA particles to cavitate was decreased by the presence of organoclay in the SEBS-g-MA phase, resulting in reduced toughening efficiency. The best micro-structure for toughness and other mechanical properties is thus to maximize the amount of exfoliated organoclay in the nylon 66 matrix rather than to have it embedded in the finely dispersed SEBS-g-MA particles. 相似文献
27.
Using photo acoustic technique, the thermal properties of CdS thin films grown by spray pyrolysis are measured. Thermal diffusivity
and conductivity in these films decrease at least two orders compared with bulk. These results are compared with our study
on nano CdS and the other available literature. The comparison is good. The dependence of thermal diffusivity on the thickness
of the layer or the size of the particles on the glass substrate are analysed from the present measurement and discussed.
The dependence of thermal diffusivity on the thickness of the layer on the glass substrate is discussed. 相似文献
28.
Ligon W.B. III Ramachandran U. 《Parallel and Distributed Systems, IEEE Transactions on》1997,8(7):681-694
lnterconnection network design plays a central role in the design of parallel systems. Most of the previous research has evaluated the performance of interconnection networks in isolation. In this study, we investigate the relationship between application program characteristics and interconnection network performance using an execution driven simulation test bed: the Reconfigurable Architecture Workbench (RAW). We simulate five topological configurations of a k-ary n-cube interconnect and four different network link models for a 4,096 node SIMD machine, and quantify the impact of the network on two application programs. We provide experimental evidence that such “in-context” simulation provides a better view of the impact of network design variables on system performance. We show that recent results, indicating that low-dimensional designs provide better ICN performance, ignore application requirements that may favor high-dimensional designs. Furthermore, applications that would appear to favor low dimensional designs may not, in fact, be significantly impacted by the network's dimensionality. We experimentally test the results of published performance models comparing the use of a synthetic load to that of a load generated by a typical application program 相似文献
29.
M. Sivabarathy S. Natarajan S. K. Ramakrishnan K. Ramachandran 《Bulletin of Materials Science》2004,27(5):403-407
Phase transition in L-alaninium oxalate is studied by using TG, DTA and photoacoustic spectroscopy. A sharp transition at
378 K by photoacoustics is observed whereas at the same temperature the endothermic energy change observed by TG and DTA is
not very sharp. This is discussed in detail with reference to the other known data for the organic crystals. 相似文献
30.
The rapid growth of the robotic industry has made it imperative to consider more seriously the safety aspects of robotic installations. Some work has been initiated recently in this area; a standard proposed by the Robotic Industries Association is a step in the right direction. This paper is based on an investigation of the state of the art in robotic safety, and contains an analysis of the sources of accidents, and the accident-prone operational phases of robotic installations. It forms the groundwork (literature survey) of a research project at the University of Windsor to develop a hardware/software-based safety system. It is suggested that both the robot manufacturer and the user should regard robotic safety as an important consideration. 相似文献