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Abstract-General-purpose computing domain has experienced strategy transfer from scale-up to scale-out in the past decade. In this paper, we take a step further to analyze ARMprocessor based cluster against Intel X86 workstation, from both energy-efficiency and cost-efficiency perspectives. Three applications are selected and evaluated to represent diversified applications, including Web server throughput, in-memory database, and video transcoding. Through detailed measurements, we make the observations that the energy-efficiency ratio of the ARM cluster against the Intel workstation varies from 2.6-9.5 in in-memory database, to approximately 1.3 in Web server application, and 1.21 in video transcoding. We also find out that for the Intel processor that adopts dynamic voltage and frequency scaling (DVFS) techniques, the power consumption is not linear with the CPU utilization level. The maximum energy saving achievable from DVFS is 20%. Finally, by utilizing a monthly cost model of data centers, we conclude that ARM cluster based data centers are feasible, and are advantageous in computationally lightweight applications, e.g. in-memory database and network-bounded Web applications. The cost advantage of ARM cluster diminishes progressively for computation-intensive applications, i.e. dynamic Web server application and video transcoding, because the number of ARM processors needed to provide comparable performance increases.

An enhanced time-domain simulation method of cutter/workpiece dynamic engagement during milling process is proposed in this article, which comprehensively considers the effect of multi-order modal characteristics of cutter system and cutter runout including offset and inclination. Based on the cutter dynamic displacement response, this article further presents the machined surface reconstruction algorithm and evaluation method for the form error. This research systematically studies and compares the calculation accuracy between the proposed method and other previous three kinds of methods. The effectiveness of the proposed method has been verified by a series of milling experiments successfully. By comparing with the other three methods, the proposed method shows a high calculation performance, especially under the milling condition with a large axial depth of cut and low damping or stiffness of cutter system. Besides, the results indicate that the form error has a strong dependence characteristic on the milling parameters, particularly on spindle speed. Additionally, cutter runout would easily cause over cut phenomenon on the machined surface and seriously deteriorate the surface roughness.