Experimental investigation of abrasive waterjet machining of Nickel based superalloys (Inconel 625)

This work explores abrasive waterjet machining (AWJM) process to improve the machining capabilities of conventional water jet machine by adding abrasive particles to the water jet. The addition of abrasive particles can turn the water jet into a modern machining tool for all materials. The experimental data of cutting parameters for hard-to-machine metal Inconel 625 is obtained. Inconel 625 is machined using an abrasive water jet and the effect of water pressure, abrasive flow rate, stand-off distance, surface quality has been studied and the response parameters are investigated. Experiments were conducted, based on Taguchi's L18 orthogonal array and the process parameters were optimized using Grey relational analysis. Further, the morphological study is made using scanning electron microscope (SEM) on the samples that were machined at optimized parameters. It is observed from the experiment that Stand-off distance is the most influencing parameter among the input parameters

Lifting Code Generation of Cardiac Physiology Simulation to Novel Compiler Technology

International audienceThe study of numerical models for the human body has become a major focus of the research community in biology and medicine. For instance, numerical ionic models of a complex organ, such as the heart, must be able to represent individual cells and their interconnections through ionic channels, forming a system with billions of cells, and requiring efficient code to handle such a large system. The modeling of the electrical system of the heart combines a compute-intensive kernel that calculates the intensity of current flowing through cell membranes, and feeds a linear solver for computing the electrical potential of each cell. Considering this context, we propose limpetMLIR, a code generator and compiler transformer to accelerate the kernel phase of ionic models and bridge the gap between compiler technology and electrophysiology simulation. LimpetMLIR makes use of the MLIR infrastructure, its dialects, and transformations to drive forward the study of ionic models, and accelerate the execution of multi-cell systems. Experiments conducted in 43 ionic models show that our limpetMLIR based code generation greatly outperforms current state-ofthe-art simulation systems by an average of 2.9×, reaching peak speedups of more than 15× in some cases. To our knowledge, this is the first work that deeply connects an optimizing compiler infrastructure to electrophysiology models of the human body, showing the potential benefits of using compiler technology in the simulation of human cell interactions

Congenital Middle Mesocolic Hernia: A Case Report

Internal hernia is herniation of a viscus, usually in the small bowel, through a normal or abnormal aperture within the peritoneal cavity. Its incidence has been reported to be 1–2 per cent. Internal hernias are classified based on location, and the hernial orifice can be either congenital or acquired. Paraduodenal hernias are the most common type (53 per cent). Paraduodenal hernia is often a misnomer and is referred to as a mesocolic hernia. Left and right mesocolic hernias are common, while middle and transverse types are rare. We are reporting a rare congenital middle mesocolic hernia presenting as a complete transection of the small intestine due to blunt injury to the abdomen

The design of an all-digital VCO-based ADC in a 65nm CMOS technology

This thesis explores the study and design of an all-digital VCO-based ADC in a 65 nm CMOS technology. As the CMOS process enters the deep submicron region, the voltage-domain-based ADCs begins to suffer in improving their performance due to the use of complex analog components. A promising solution to improve the performance of an ADC is to employ as many as possible digital components in a time-domain-based ADC, where it uses the time resolution of an analog signal rather than the voltage resolution. In comparison, as the CMOS process scales down, the time resolution of an analog signal has found superior than the voltage resolution of an analog signal. In recent years, such time-domain-based ADCs have been taken an immense interest due to its inherent features and their design reasons. In this thesis work, the VCO-based ADC design, falls under the category of time-based ADCs which consists of a VCO and an appropriate digital processing circuitry. The employed VCO is used to convert a voltage-based signal into a time signal and thereby it also acts as a time-based quantizer. Then the resulting quantized-time signal is converted into a digital signal by an appropriate digital technique. After different architecture exploration, a conventional VCO-based ADC architecture is implemented in a high-level model to understand the characteristic behaviour of this time-based ADC and then a comprehensive functional schematic-level is designed in reference with the implemented behavioural model using cadence design environment. The performance has been verified using the mixed-levels, of transistor and behavioural-levels due to the greater simulation time of the implemented design. ADC’s dynamic performance has been evaluated using various experiments and simulations. Overall, the simulation experiments showed that the design was found to reach an ENOB of 4.9-bit at 572 MHz speed of sample per second, when a 120 MHz analog signal is applied. The achieved peak performance of the design was a SNR of 40 dB, SFDR of 34 dB and an SNDR of 31 dB over a 120 MHz BW at a 1 V supply voltage. Without any complex building blocks, this VCO-based all-digital ADC design provided a key feature of inherent noise shaping property and also found to be well compatible at the deep submicron region

GPU Code Generation of Cardiac Electrophysiology Simulation with MLIR

International audienceWe show the benefits of the novel MLIR compiler technology to the generation of code from a DSL, namely EasyML used in openCARP, a widely used simulator in the cardiac electrophysiology community. Building on an existing work that deeply modified open-CARP's native DSL code generator to enable efficient vectorized CPU code, we extend the code generation for GPUs (Nvidia CUDA and AMD ROCm). Generating optimized code for different accelerators requires specific optimizations and we review how MLIR has been used to enable multi-target code generation from an integrated generator. Experiments conducted on the 48 ionic models provided by openCARP show that the GPU code executes 3.17× faster and delivers more than 7× FLOPS per watt than the vectorized CPU code, on an Nvidia A100 GPU versus a 36-cores AVX-512 Intel CPU

Parametric optimization of abrasive water jet machining of beryllium copper using Taguchi grey relational analysis

Abrasive water jet machining is a non-conventional machining process to machine complicated intricate shapes, abrasive water jet machine is most suited as it can cut both conducting and nonconductive material with better finish. Beryllium copper grade C25 is used as a material for machining considering its applications in petroleum nozzle washer used in petroleum products and also in marine, aerospace industries. In this work, the predominant process parameters like pressure, abrasive flow, and standoff distance are varied to obtain optimum values of response parameters like (MRR) material removal rate and surface roughness. Since the multi-response optimisation cannot be performed by conventional Taguchi method, Grey-Taguchi methodology is used. Abrasive flow rate and standoff distance are the most influenced process parameters to obtain higher MRR and also for better surface-roughness. After obtaining the optimised values for machining parameters using Grey-Taguchi Methodology. A confirmatory test is performed to test the integrity of the obtained results

Experimental investigation of electrochemical micro-machining process parameters on stainless steel 316 using sodium chloride electrolyte

In this paper, the experimental investigation of electrochemical micro-machining (ECMM) process on stainless steel 316 by varying the effect of applied voltage, electrolyte concentration, micro-tool feed rate and duty cycle. The machining performance such as material removal rate (MRR) and overcut (OC). Taguchi design of experiment has been used to carry out the design of input process parameters and their levels. Microscopic image has been used to study the surface topography of the electrochemical micro-machined work piece surface. The experimental results attain that the effect of electrolyte concentration and duty cycle has most significant factors for the machining of stainless steel 316 by electrochemical micro-machining (ECMM) process. The optimize process parameters for higher material removal rate and lower overcut are found out using grey relational approach, and finally, the confirmation tests were carried out in the electrochemical micro-machining process

Nekara: Generalized Concurrency Testing

Testing concurrent systems remains an uncomfortable problem for developers. The common industrial practice is to stress-test a system against large workloads, with the hope of triggering enough corner-case interleavings that reveal bugs. However, stress testing is often inefficient and its ability to get coverage of interleavings is unclear. In reaction, the research community has proposed the idea of systematic testing, where a tool takes over the scheduling of concurrent actions so that it can perform an algorithmic search over the space of interleavings.We present an experience paper on the application of systematic testing to several case studies. We separate the algorithmic advancements in prior work (on searching the large space of interleavings) from the engineering of their tools. The latter was unsatisfactory; often the tools were limited to a small domain, hard to maintain, and hard to extend to other domains. We designed Nekara, an open-source cross-platform library for easily building custom systematic testing solutions.We show that (1) Nekara can effectively encapsulate state-of-the-art exploration algorithms by evaluating on prior bench-marks, and (2) Nekara can be applied to a wide variety of scenarios, including existing open-source systems as well as production distributed services of Microsoft Azure. Nekara was easy to use, improved testing, and found multiple new bugs. © 2021 IEEE