Current Issue : April - June Volume : 2016 Issue Number : 2 Articles : 6 Articles
A fault tolerance is an important property in order to achieve performance levels for important attributes\nfor a system�s dependability, reliability, availability and Quality of Service (QoS). In this survey a comprehensive\nreview of representative works on fault tolerance in cloud computing is presented, in which general readers will be\nprovided an overview of the concepts and practices of a fault-tolerance computing. Cloud computing service\nproviders will rise and fall based on their ability to execute and deliver a satisfactory QoS in primary areas such as\ndependability. Many enterprise users are wary of the public clouds' dependability limitations, but also curious about\nthe possibility of adopting the technologies, designs and best practices of clouds for their own data centers such as\nprivate clouds. The situation is evolving rapidly with public, private and hybrid clouds, as vendors and users are\nstruggling to keep up with new developments....
Model Output Statistics (MOS) is a well-known technique that allows improving outputs from numerical\natmospheric models. In this contribution, we present the development of a MOS algorithm\nto improve air quality forecasts in Catalonia, a region in the northeast of Spain. These forecasts are\nobtained from an Eulerian coupled air quality modelling system developed by Meteosim. Nitrogen\nDioxide (NO2), Particulate Matter (PM10) and Ozone (03) have been the pollutants considered and\nthe methodology has been applied on statistical values of these pollutants according to regulatory\nlevels. Four MOS algorithms have been developed, characterized by different approaches in relation\nwith seasonal stratification and stratification according to the measurement stations considered.\nAlgorithms have been compared among them in order to obtain a MOS that reduces the\nforecast uncertainties. Results obtained show that the best MOS designed increases the accuracy\nof NO2 maximum 1-h daily value forecast from 71% to 75%, from 68% to 81% in the case of daily\nvalues of PM10, and finally, the accuracy of O3 maximum 1-h daily value from 79% to 87%....
Matrix method is being proposed for qualitative evaluation of the reliability of technical systems\non a finite set of structural elements. We are introducing the criteria for qualitative assessment of\nthe reliability in the form of structural reliability of the system as the probability of the trouble proof\nstate of this system and the significancy of the individual elements in ensuring the structural\nreliability of the system as a general aggregate of conditional probabilities, which compose two (2\nÃ?â?? 2) matrices of significancy for each element. We are using chain diagrams for solving the combinat ronic\nproblems and matrices for algorithmization of calculating procedures....
Scan statistics are mostly used to detect spatial areas or time intervals in which the mean level of a given variable is more important.\nSometimes, when this variable is continuous, there is an interest in looking for clusters in which its variability is more important. In\nthis paper, two scan statistics are introduced for identifying clusters of values exhibiting higher variance. Like many classical scan\nstatistics, the first one relies on a generalized likelihood ratio test whereas the second one is based on ratios of empirical variances.\nThese methods are useful to identify spatial areas or time intervals in which the variability of a given variable is more important.\nIn an application of the new methods, I look for geographical clusters of high-variability income in France and then for residuals\nexhibiting higher variance in a linear regression context....
The renewal process define as a counting process where the times between the count renewals is a random variables and their distribution\nis identical. In the electricity generation machines there are spare parts replaced due to damage or expired and replacement process occur\nrepeatedly and the renewal process of here assume that times between replacements are independent random variables and it has identical\nprobability distribution. In this paper, renewal process model has applied on the time of fault for machine in Bahri Thermal Station for\nelectricity generation, which is belong to the National Electricity Authority in Sudan during the period (2011-2015). Through the renewal\nprocess model estimation is clear that, the failure time (renewal) for the machines follow Weibull distribution with 2-parameters and\nwhen the time trend has been tested it is clear that no trend exist which mean that the renewal process represent Homogeneous Poisson\nProcess (HPP), and the repair rate (renewal) is occurred constantly. In addition, the findings approve that whenever the repair rate (renewal)\nincrease the mean time between failures (MTBF) increases too and this clear in machine no (6)....
This paper introduces a new four-parameter lifetime model, which extends the Marshall-Olkin Fr�´echet distribution\nintroduced by Krishna et al. (2013), called the transmuted Marshall-Olkin Fr�´echet distribution. Various structural\nproperties including ordinary and incomplete moments, quantile and generating function, R�´enyi and q-entropies\nand order statistics are derived. The maximum likelihood method is used to estimate the model parameters. We\nillustrate the superiority of the proposed distribution over other existing distributions in the literature in modeling\ntwo real life data sets....
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