No abstract

Electro-discharge machining (EDM) process is one of the most successful non-conventional machining processes for the last three to four decades in machining very hard materials which are tough to machine by conventional machining process. In the EDM process, besides the erosion of workpiece material, the inherent nature of the process leads to some tool material removal also. This nature of EDM process has been exploited by the researchers which led to the invention of Electro-discharge coating (EDC). EDC is a surface modification technique where tool material gets deposited on the substrate surface due to the sparking effect. It works on reverse polarity to that of EDM. A literature review based on the phenomenon of surface improvement by EDC process and also the future drifts of its application are shown in this paper.

In this study, the performance of impellers with the same outlet diameter having different blade numbers for centrifugal pumps is thoroughly evaluated The impeller outlet diameter, the blade angle and the blade uumbers are the most critical parameters which affect the performance of centrifugal pumps.. The model pump has a design rotation speed of 4000 rpm and an impeller with 4

This paper introduces the surface modi¯cation of Al-6351 alloy by green compact SiC-Cu electrode using electro-discharge coating (EDC) process. A Taguchi L-16 orthogonal array is employed to investigate the process by varying tool parameters like composition and compaction load and electro-discharge machining (EDM) parameters like pulse-on time and peak current. Material deposition rate (MDR), tool wear rate (TWR) and surface roughness (SR) are measured on the coated specimens. An optimum condition is achieved by formulating overall evaluation criteria (OEC), which combines multi-objective task into a single index. The signal-to-noise (S/N) ratio, and the analysis of variance (ANOVA) is employed to investigate the e®ect of relevant process parameters. A con¯rmation test is conducted based on optimal process parameters and experimental results are provided to illustrate the e®ectiveness of this approach. The modi¯ed surface is characterized by optical microscope and X-ray di®raction (XRD) analysis. XRD analysis of the deposited layer con¯rmed the transfer of tool materials to the work surface and formation of inter-metallic phases. The micro-hardness of the resulting composite layer is also measured which is 1.5-3 times more than work material's one and highest layer thickness (LT) of 83.644 m has been successfully achieved.

We analyze a class of first significant digit (FSD) histogram restoration techniques designed to cover up traces of previous JPEG compressions under a minimum cost constraint. We argue that such minimal distortion mappings introduce strong artifacts to the distribution of DCT coefficients, which become particularly prevalent in the domain of second significant digits (SSDs). Empirical findings from large image databases give insight into SSD distributions of DCT coefficients of natural images and demonstrate how images that underwent FSD histogram restoration deviate from natural images.