Helical deep hole drilling is a process frequently used in industrial applications to produce bores with a large length to diameter ratio. For better cooling and lubrication, the deep drilling oil is fed directly into the bore hole via two internal cooling channels. Due to the inaccessibility of the cutting area, experimental investigations that provide information on the actual machining and cooling behavior are difficult to carry out. In this paper, the distribution of the deep drilling oil is investigated both experimentally and simulatively and the results are evaluated. For the Computational Fluid Dynamics (CFD) simulation, two different turbulence models, i.e. the RANS k-ω-SST and hybrid SAS-SST model, are used and compared. Thereby, the actual used deep drilling oil is modelled instead of using fluid dynamic parameters of water, as is often the case. With the hybrid SAS-SST model, the flow could be analyzed much better than with the RANS k-ω-SST model and thus the processes that take place during helical deep drilling could be simulated with realistic details. Both the experimental and the simulative results show that the deep drilling oil movement is almost exclusively generated by the tool rotation. At the tool’s cutting edges and in the flute, the flow velocity drops to zero for the most part, so that no efficient cooling and lubrication could take place there. In addition, cavitation bubbles form and implode, concluding in the assumption that the process heat is not adequately dissipated and the removal of chips is adversely affected, which in turn can affect the service life of the tool and the bore quality. The carried out investigations show that the application of CFD simulation is an important research instrument in machining technology and that there is still great potential in the area of tool and process optimization.
This article describes a classification tool to cluster SARAL/AltiKa waveforms. The tool was made using Python scripts. Radar altimetry systems (e.g., SARAL/AltiKa) measures the distance from the satellite centre to a target surface by calculating the satellite-to-surface round-trip time of a radar pulse. An altimeter waveform represents the energy reflected by the earth’s surface to the satellite antenna with respect to time. The tool clusters the altimetric waveforms data into desired groups. For the clustering, we used evolutionary minimize indexing function (EMIF) with k-means cluster mechanism. The idea was to develop a simple interface which takes the altimetry waveforms data from a folder as inputs and provides single value (using EMIF algorithm) for each waveform. These values are further used for clustering. This is a simple light weighted tool and user can easily interact with it.
This paper attempts to shed light on the current role of academia in the context of rural areas of low population density, which are regional interaction models. In this study, we follow a qualitative research methodology of a case study. We found that through the case study applied to a hotel unit, that the Academia can through its third mission, and in the context of regional triple helix dynamics (Academia-Business-government interaction), play an important role in terms of knowledge dissemination, wealth creation and employability. The limitations, which our study presents, are principally related to the measurement of the variables. Some of the characteristics of education should be studied more deeply. In the instance of a case study applied to the hospitality industry, it is important to take as limitations of the study to its direct application to any economic context. This study allowed however, contribute to the enrichment of literature through case studies presented in the hospitality industry.
Simple mathematical expressions are given for the betweenness centrality of nodes in trees, forests and cycles. As application, a centrality test is given for when a network might be a forest.
The present article reports the applications of Caputo-Fabrizio time-fractional derivatives. This article generalizes the idea of unsteady MHD free convective flow in a Walters.-B fluid with heat and mass transfer study over an exponential isothermal vertical plate embedded in a porous medium. The governing equations are converted into dimensionless form and extended to fractional model. The generalized Walters-B fluid model has been solved analytically using the Laplace transform technique. From the general solutions we reduce limiting solutions when to the similar motion for Newtonian fluid. The corresponding expressions for and Nusselt and Sherwood numbers are also assessed. Numerical results for velocity, temperature and concentration are demonstrated graphically for various factors of interest and discussed. As a result, we have plotted the influence of fractional parameter on fluid flow and drawn comparison between fractional Walters’-B and fractional Newtonian fluid and found that fractional Newtonian fluid is faster than fractional Walters’-B fluids.
The cambucizeiro (Campomanesia phaea), belonging to the Myrtaceae family, is a native plant of the Brazilian Atlantic Forest. The description of the characteristics of the cambucizeiro fruits is important to support new genetic improvement works and its commercial exploitation, especially regarding the processing of the fruit. The present work aimed to perform the morphological and chemical characterization of the cambucizeiro fruits. Fifty-eight accessions, from different locations in the Atlantic Forest and Serra do Mar in the state of São Paulo, were collected, propagated by seeds and one specimen of each accessory is at the Seedling Production Center in São Bento do Sapucaí (SP). Forty fruits from each access were collected in May and submitted to the following analyses: longitudinal and transversal diameter, total fruit fresh mass, number and mass of seeds, total soluble solids, % citric acid, ratio, firmness, vitamin C and coloration. Fruit conformation varies intensely among accessions. The number of seeds is not a good indicator for the relation with the fruit mass, but the mass of one thousand seeds. Some accessions have high soluble solids content, but, on the other hand, the vast majority have fruits with high acidity. Cambuci is an excellent source of vitamin C. The fruits of the accessions are green in color, persisting an opaque shade when ripe.
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