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One of the techniques for improving the performance of distributed systems is data replication, wherein new replicas are created to provide more accessibility, fault tolerance and lower access cost of the data. In this paper, the authors propose a community-based solution for the management of data replication, based on the graph model of communication latency between computing and storage nodes. Communities are the clusters of nodes that the communication latency between the nodes are minimum values. The purpose of this study if to, by using this method, minimize the latency and access cost of the data.

This paper used the Louvain algorithm for finding the best communities. In the proposed algorithm, by requesting a file according to the nodes of each community, the cost of accessing the file located out of the applicant’s community was calculated and the results were accumulated. On exceeding the accumulated costs from a specified threshold, a new replica of the file was created in the applicant’s community. Besides, the number of replicas of each file should be limited to prevent the system from creating useless and redundant data.

To evaluate the method, four metrics were introduced and measured, including communication latency, response time, data access cost and data redundancy. The results indicated acceptable improvement in all of them.

So far, this is the first research that aims at managing the replicas via community detection algorithms. It opens many opportunities for further studies in this area.

This paper aims to provide a method for media resource allocation in Cloud systems for supporting green computing policies, as well as attempting to improve the overall performance of system by optimizing the communication latencies.

A common method for resource allocation is using resource agent that takes the budgets/prices of applicants/resources and creates a probability matrix of allocation according to the policies of system. Two general policies for optimization are latency optimization and green computing. Presented heuristic for latencies is so that the average latencies of communication between applicant and resource are measured, and they will affect the next decision. For gaining green computing, it is attempted to consolidate the allocated resources on smaller number of physical machines. So calculation formula of the price of each resource is modified to decrease the probability of allocating the resources on the machine with least allocated resources.

Results of proposed method indicates its success in both green computing and improving the performance. Experiments show decreasing 21.4 per cent of response time simultaneously with increasing tasks in the tested range. The maximum and minimum of saved energy is acceptable and reported as 79.2 and 16.8 per cent.

Like other centralized solutions, the proposed method suffers from the limitations of centralized resource agent, like bottle neck. But the implementation of distributed resource agent is postponed to future work.

Proposed method presents heuristics for improving the performance and gaining green computing. The key feature is formulating all the details and considering pitch variables for controlling the policies of system.

The success of e-commerce websites depends on their effective communication and influence on their users. At first glance, the users are impressed by the website design and, if inspired, they would continue their operations on the website. This paper aims to evaluate the effects of visual aesthetic of the Web pages on users’ behavior in online shopping environment. In particular, the paper aims to evaluate the elements of visual aesthetic on the organism variables (i.e. “satisfaction,” “arousal,” “perceived on-line service quality” and “trust”) and measure them on the users’ response (i.e. purchase, comparison and re-visit).

Using the stimulus–organism–response (S-O-R) framework, the authors first assessed direct and indirect effects of visual aesthetics of e-commerce websites on customer responses. Then, the Visual Aesthetics of Websites Inventory (VisAWI) method was used to examine the effects of four dimensions (i.e. craftsmanship, simplicity, diversity and colorfulness) on users’ perceived website aesthetics. To do so, DigiKala.com, a famous Iranian e-commerce website was selected and the questionnaires were distributed among its users.

The study results revealed that the website aesthetics in the S-O-R evaluation had the greatest direct impact on “perceived quality of online services,” “trust,” “satisfaction” and “arousal,” respectively. These variables also indirectly affected “shopping,” “revisit” and “comparison to similar products on other websites.” Regarding the evaluations based on the VisAWI, the component “craftsmanship” played the most central role in expressing the website aesthetics, followed by the variables “simplicity,” “diversity” and “colorfulness,” respectively.

Although the considerable effect of Web aesthetics on customers’ purchase behavior has been identified in previous research, it has not been accurately measured. Furthermore, studies on Web aesthetics are mostly limited to information systems’ users and do not concern consumers. Therefore, considering the increasing growth in online shopping and the significance of Web aesthetics to online consumers, investigating how consumers respond to Web aesthetics is of vital importance.