Fundamentals of Mechanical Working

Author(s):  
Amit Bhaduri
Keyword(s):  
1971 ◽  
Vol 10 (1) ◽  
pp. 21-27 ◽  
Author(s):  
M. A. M. A. Younes ◽  
P. S. Walker ◽  
P. C. Seller ◽  
D. Dowson ◽  
V. Wright

2017 ◽  
Vol 62 (3) ◽  
pp. 1443-1447 ◽  
Author(s):  
T. Maciąg ◽  
J. Wieczorek ◽  
B. Węcki

AbstractElectropolishing is electrochemical method used in metal working that has a vital role in production of medical apparatus, in food or electric industry. The purpose of this paper is to determine optimal current parameters and time required for conducting electropolishing process from the perspective of changes of surface microgeometry. Furthermore, effect of different types of mechanical working used before electropolishing on final surface state was evaluated by observation in changes of topography. Research was conducted on electrolytic copper and brass. Analysis of surface geometry and its parameters (Ra, Sa) was used as criterion describing efficiency of chemical electropolishing. Results of the experiment allow for current parameter optimization of electrochemical polishing process for selected non-ferrous alloys with preliminary mechanical preparation of the surface.


2021 ◽  
Vol 53 (6) ◽  
pp. 139-174
Author(s):  
Laetitia Lenel

The article investigates the methods and conceptions of statistical inference used in business forecasting in the United States and in Europe in the 1920s. After presenting the methods and arguments used by the members of the Harvard Committee on Economic Research in the first years after its establishment in 1919, the article explores the far-reaching changes in method and conviction from 1922 on. The members’ realization that the future evolved differently than predicted prompted them to give up their hope for mechanical means of forecasting and to revoke their calls for the employment of the mathematical theory of probability in economics. Instead, they established an extensive correspondence with economic and political decision-makers that allowed them to base their forecasts on “inside information.” Subsequently, the article traces European attempts to adopt the Harvard Index of General Business Conditions in the early 1920s. Impressed by the seemingly mechanical working of the Harvard index, European economists and statisticians sought to establish similar indices for their countries. However, numerous revisions of the Harvard index in the mid-1920s cast doubt on the universality of the index and the existence of stable patterns and led European researchers to pursue different paths of investigation. The article complicates the larger history of statistical inference in economics in two meaningful ways. First, it argues that statistical inference with probability was not the long-sought solution for the problem of objectivity but a long-contested, and repeatedly discarded, approach. Second, it shows that these contestations were often triggered by deviations between forecasts and the conditions actually observed and by this means argues for the importance of the historical context in the history of economics.


1989 ◽  
Vol 32 (8) ◽  
pp. 774-776
Author(s):  
A. S. Mironenko ◽  
Yu. V. Slobodyanik ◽  
L. A. Zhivova

2021 ◽  
Author(s):  
ANSHUL SINGHAL ◽  
AMY LANGHORST ◽  
ANKUSH BANSAL ◽  
MIHAELA BANU ◽  
ALAN TAUB

Natural plant fibers compared to glass fibers can provide a cost effective, lightweight and carbon negative reinforcement for polymer composites. However, the current commercial fiber extraction process induces defects including middle lamellae weakening during retting and kink bands during mechanical working. This leads to high variability in mechanical properties, making these fibers less favorable for structural applications at industrial scale. The aim of current research is to reduce this variability by studying the underlying mechanisms of natural fiber extraction to minimize fiber damage occurring at various steps in the process. In this study, flax stems were retted using the conventional dew/field and lab scale controlled enzymatic retting. The hand decorticated fibers from both methods were compared and enzymatic retting showed promising results in producing fine and uniform fibers as compared to fibers extracted by dew retting. To establish the constitutive parameters of the fibers for Finite Element Modeling (FEM), single retted flax stems were compression tested using a Texture Analyzer. This data can serve as the basis for modeling the mechanical deformation of plant stems passing through breaking rollers which is the first step in extraction after retting. The goal is to optimize the roller design and process conditions required to extract fibers with minimal damage and variability.


2011 ◽  
Vol 65 ◽  
pp. 88-91
Author(s):  
Miao Li ◽  
Hui Bin Gao

To meet requirement of swiftness and minimization for the tracking system as well as realize horizontal high accuracy tracking measurement, the automatic servo tracking measurement system has been designed. The two closed loop control, bisection method and compound control have been applied into the system. Experimental results show that the maximum tracking error can be limited to less than 0.5°and the regulator time can be 0.04s. The control project resonance frequency should be more than 200Hz and the sample frequency should be more than 400Hz to meet the control accuracy requirement. And these specific mechanical properties indexes are useful to mechanical working to make sure the design can be realization. So the research in this paper has important value to the engineering practice.


Author(s):  
E Toshmatov ◽  
A Akhmedov ◽  
Z Ibragimova
Keyword(s):  

2007 ◽  
Vol 30 (7) ◽  
pp. 604-610 ◽  
Author(s):  
G. Arpesella ◽  
E. Mikus ◽  
M. Arabia ◽  
A. Loforte ◽  
P. M. Mikus

Mechanical circulatory support is an essential issue in the management of patients with end-stage cardiac failure. The aim of this study is to evaluate the efficacy of temporary support with a centrifugal blood pump as bridge to heart function recovery or bridge to transplantation. Heart recovery is achieved by improving ventricular mechanical working conditions with proper modifications of preload and afterload. This article assesses the advantages of a novel “cardiac chambers” cannulation setting versus the traditional one, in the case of biventricular or isolated right ventricular failure. The study was conducted using a numerical computer model based on the work by Guyton, Sagawa, Westerhof, and Noordergraaf. Simulation of the planned trials was achieved by changing the model parameters, the pump angular velocity, and the inflow and outflow settings. (Int J Artif Organs 2007; 30: 604–10)


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