1,721,096 research outputs found
Micro drilling of hard-to-cut materials: An experimental analysis
Full text linkThe introduction of machine tools specifically designed and industrialised for micro cutting processes, the development of high performance micro tools, and the possibility of easily realising complex shaped surfaces have increased the competitiveness and the industrial interest on these processes. Consequently, many researchers are studying the phenomena involved in the mechanics of micro cutting processes. This paper is focused on the micro drilling process for difficult to cut materials. An experimental analysis, consisting tool life tests, was performed with the aim of highlighting limits and advantages of this cutting process. Three hard-to-cut alloys, namely AISI 310H stainless steel, Hastelloy C22 and Inconel 625 nickel based alloys, were tested. By using standard micro drills, holes 500 μm diameter with two different depths were realised by utilising peck drilling strategy. The final results showed that, differently from macro scale cutting, the workability of hard-to-cut materials at micro scale is mainly affected by the material ductility rather than its hardness
Evidence of recent causal decoupling between solar radiation and global temperature
No full textThe Sun has surely been a major external forcing to the climate system throughout the
Holocene. Nevertheless, opposite trends in solar radiation and temperatures have been
empirically identified in the last few decades. Here, by means of an inferential method—the
Granger causality analysis—we analyze this situation and, for the first time, show that an
evident causal decoupling between total solar irradiance and global temperature has appeared
since the 1960s
Container-Based Orchestration in Cloud: State of the Art and Challenges
No full textHow to effectively manage increasingly complex enterprise computing environments is one of the hardest challenges that most organizations have to face in the era of cloud computing, big data and IoT. Advanced automation and orchestration systems are the most valuable solutions helping IT staff to handle large-scale cloud data centers. Containers are the new revolution in the cloud computing world, they are more lightweight than VMs, and can radically decrease both the start up time of instances and the processing and storage overhead with respect to traditional VMs. The aim of this paper is to provide a comprehensive description of cloud orchestration approaches with containers, analyzing current research efforts, existing solutions and presenting issues and challenges facing this topic
Finite element simulation of tool wear in machining of nickel-chromiumbased superalloy
Full text linkThe phenomenon of tool wear strongly affects the efficiency of machining and the quality of machined products. The experimental approach to investigate tool wear requires several time consuming tests. Finite Element Methods (FEM) can be utilized to predict tool wear and tool life as function of process parameters and tool geometry. The commercial software for Finite Element Analysis (FEA) are limited by the impossibility to update the geometry of the worn tool. This research utilizes a self-released subroutine in order to modify the tool geometry in DEFORM 3D simulations by considering the volume reduction of the tool. The model was validated with experimental data obtained by drilling tests on Inconel 718 using conventional metal working fluids (MWF). The correct profile of the simulated worn tool was individuated by comparing the prediction of the simulation with the real tool geometry. The FEM simulation allowed to predict how torque changes during the tool life. In a predictive maintenance perspective, the model can be implemented to optimize the tools replacement
Anthropogenic global warming hypothesis: testing its robustness by Granger causality analysis
No full textExamining Granger causality between atmospheric parameters and radon
No full textIn this paper, we study the relationship between atmospheric parameters (i.e.,
temperature and humidity) and radon data. We use the linear Granger causality in order to
observe possible connections, on short and mid time scale periods, between radon time
series and meteorological parameters that strongly influence radon emissions. The analysis
suggests radon emission is not affected by these atmospheric parameters on short periods,
while there is an evidence of Granger causality on mid periods
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