Grid computing is a term referring to the combination of computer resources from multiple administrative domains to reach a common computational platform. Mobile Computing is a Generic word that introduces using of movable, handheld devices with wireless communication, for processing data. Mobile Computing focused on providing access to data, information, services and communications anywhere and anytime with all significances. Mobile grids simultaneously are related with traditional grids and mobile computing technologies. This kind of grids inherits all bequests of traditional grid computing and has the trait that supports mobile users and devices in a wireless, Transparent, secure and efficient way. In this paper we suggest a job replica count determiner based on fuzzy inference system to improve mobile grid performance. Simulation results shows that our approach improve parameters like system throughput and network traffic, though job failure rate remains in same condition and mean response time become worse.

A data-intensive computing platform, encountered in some grid and cloud computing applications, includes numerous tasks that process, transfer or analysis large data  les. In such environments, there are large and geographically distributed users that need these huge data. Data management is one of the main challenges of distributed computing environment since data plays on devoted role. Dynamic data replication techniques have been widely applied to improve data access and availability. In order to introduce an appropriate data replication algorithm, there are four important problems that must be solved. 1) Which  le should be replicated; 2) How many suitable new replicas should be stored; 3) Where the new replicas should be placed; 4) Which replica should be deleted to make room for new copies. In this paper, we focus particularly on replica replace-ment issue which makes a signi cant di erence in the e ciency of replication algorithm. We survey

Background: This study compared the amount of residual cement at the margin of implant-supported crowns cemented using the polytetrafluoroethylene (PTFE) tape, replica technique, and conventional cementation technique. Methods: In this in vitro experimental study, a mandibular model underwent full-arch scanning. The right first molar tooth was eliminated on the scan using Exocad software, and a regular implant analog was modelled using the Exocad model creator. The designed abutment was then printed. The implant analog was fixed in place with acrylic resin and scanned using a scan body. A full-zirconia custom abutment was then designed by Exocad. Abutments were fabricated using zirconia and sintered. Twenty-seven resin crowns were fabricated for the abutments, and their fit was assessed. Nine crowns were conventionally cemented by filling half of the crown space with cement, 9 crowns were cemented using PTFE tape, and the remaining 9 were first placed on a resin replica and then cemented on the abutments. The residual cement was weighed using a digital scale, and the groups were compared by one-way ANOVA and LSD test (α=0.05). Results: The amount of residual cement was significantly different among the three groups, indicating that the amount of residual cement was the highest in conventional cementation, and the lowest in the replica group (P < 0.05). Pairwise comparisons showed significant differences between all groups (P < 0.05). Conclusions: The replica technique followed by the PTFE tape resulted in the minimum amount of residual cement at the margin of implant-supported cement-retained crowns and are preferred for use in the clinical setting.

Background: This study compared the amount of residual cement at the margin of implant-supported crowns cemented using the polytetrafluoroethylene (PTFE) tape, replica technique, and conventional cementation technique. Methods: In this in vitro experimental study, a mandibular model underwent full-arch scanning. The right first molar tooth was eliminated on the scan using Exocad software, and a regular implant analog was modelled using the Exocad model creator. The designed abutment was then printed. The implant analog was fixed in place with acrylic resin and scanned using a scan body. A full-zirconia custom abutment was then designed by Exocad. Abutments were fabricated using zirconia and sintered. Twenty-seven resin crowns were fabricated for the abutments, and their fit was assessed. Nine crowns were conventionally cemented by filling half of the crown space with cement, 9 crowns were cemented using PTFE tape, and the remaining 9 were first placed on a resin replica and then cemented on the abutments. The residual cement was weighed using a digital scale, and the groups were compared by one-way ANOVA and LSD test (α,= 0. 05). Results: The amount of residual cement was significantly different among the three groups, indicating that the amount of residual cement was the highest in conventional cementation, and the lowest in the replica group (P < 0. 05). Pairwise comparisons showed significant differences between all groups (P < 0. 05). Conclusions: The replica technique followed by the PTFE tape resulted in the minimum amount of residual cement at the margin of implant-supported cement-retained crowns and are preferred for use in the clinical setting.

Data grids support access to widely distributed storage for large numbers of users accessing potentially many files. To enhance access time, replication at nearby sites may be used. Data replication, a technique much investigated by data grid researchers in past years creates multiple replicas of file and places them in conventional locations to shorten file access times. One of the problems in data replication is creation of replicas, replica placement and replica selection. Dynamic creation of replicas in an appropriate site by data replication strategy can increase the systems performance. In this paper, we propose a data replication algorithm, called the Utility-base Data replication (UDR) algorithm that improves file access time. Each grid site has its own capabilities and characteristics; therefore, choosing one specific site from many sites that have the needed data is a key and significant decision. The replica selection problem has been studied by many researchers who only considered response time as a criterion for the selection process. Therefore, in this study, we addressed the problem of how to select the best replica for the users' jobs. Our approach is simulated using a data grid simulator, OptorSim, developed by European Data Grid projects. Comparing to the previous work the experimentation shows the improvement in the overall performance.

As grow as the data-intensive applications in cloud computing day after day, data popularity in this environment becomes critical and important. Hence to improve data availability and efficient accesses to popular data, replication algorithms are now widely used in distributed systems. However, most of them only replicate the static number of replicas on some requested chosen sites and it is obviously not enough for more reasonable performance. In addition, the failure of request is one of the most common issue within the data centers. To compensate these problems, we, propose a new data replication strategy to provide cost-effective availability, minimize the response time of applications and make load balancing for cloud storage. The proposed replication strategy has three different steps which are the identification of data file to replicate, placing new replicas, and replacing replicas. In the first step, it finds the most requested files for replication. In the second step, it selects the best site by consideration of the frequency of requests for replica, the last time the replica was requested, failure probability, centrality factor and storage usage) for storing new replica to reduce access time. In the third step, the replacement decision is made in order to provide better resource usage. The proposed strategy can ascertain the importance of valuable replicas based on the number of accesses in future, the availability of the file, the last time the replica was requested, and size of replica. Our proposed algorithm evaluated by CloudSim simulator and results confirmed the better performance of hybrid replication strategy in terms of mean response time, effective network usages, replication frequency, degree of imbalance, and number of communications.