Data Grid provides sharing services for very large data around the world. Data replication is one of the most effective approaches to reduce access latency and response time. In addition to the benefits, replication has costs such as storage and bandwidth consumption, especially when storage space is low and limited. Therefore,  the data replacement should be done wisely. In this p...

Large-scale data management is a critical problem in a distributed system such as cloud,P2P system, World Wide Web (WWW), and Data Grid. One of the effective solutions is data replicationtechnique, which efficiently reduces the cost of communication and improves the data reliability andresponse time. Various replication methods can be proposed depending on when, where, and howreplicas are gener...

Data Envelopment Analysis (DEA) is a mathematical programming technique for evaluatingthe relative efficiency of a set of Decision Making Units (DMUs) and can also be utilized forsetting target. Target setting is one of the important subjects since according to its resultsefficiency can be increased. An important issue to be currently discussed, is to set targetwhile considering share data. The...

the present study is an attempt toward evaluating the performance of portfolios using mean-variance-skewness model with negative data. mean-variance non-linear framework and mean-variance-skewness non- linear framework had been proposed based on data envelopment analysis, which the variance of the assets had been used as an input to the dea and expected return and skewness were the output. conv...

background policy makers need models to be able to detect groups at high risk of hiv infection. incomplete records and dirty data are frequently seen in national data sets. presence of missing data challenges the practice of model development. several studies suggested that performance of imputation methods is acceptable when missing rate is moderate. one of the issues which was of less concern...

recently, farzipoor saen [journal of the operational research society, 60(11), 1575–1582 (2009)] proposed a method based on data envelopment analysis to identify optimistic efficient suppliers in the presence of nondiscretionary factors-imprecise data. this short communication aims at showing a computational error in computing the value of preference intensity parameter in farzipoor saen’s [1] ...

one of the new topics in dea is the data with integer values. in dea classic models, it is assumed that input and output variables have real values. however, in many cases, some inputs or outputs can have integer values. measuring cost efficiency is another method to evaluate the performance and assess the capabilities of a single decision-making unit for manufacturing current products at a min...

Exploration geochemistry continues to be a major contributor to mineral exploration programs at all scales. The decade has spanned a complete economic cycle in the minerals industry, during which there has been a change in exploration emphasis from the dominance of Au and diamonds to the addition of a range of base metals and the recent revival of U exploration. Increasing metal prices and the ...

fuzzy rule-based classification system (frbcs) is a popular machine learning technique for classification purposes. one of the major issues when applying it on imbalanced data sets is its biased to the majority class, such that, it performs poorly in respect to the minority class. however many cases the minority classes are more important than the majority ones. in this paper, we have extended ...

the diagnostic accuracy of single photon emission computed tomography (spect) is profoundly influenced by attenuation phenomenon. soft tissue attenuation degrades cardiac spect image quality, thereby decreasing the possibility of the detection of the lesions. a variety of correction techniques based on different assumptions have been used to reduce the impact of attenuation. several types of sy...