Prediction of performance parameters in Wire EDM of HcHcr steel using Artificial Neural Network

Electrical discharge machining has been extensively used for cutting intricate contours or delicate cavities that would be difficult to produce with a conventional machining methods or tools. Wire EDM is in use for a long time for cutting punches and dies, shaped pockets and other complex shaped parts. Performance of the process is mainly depends on many parameters used during process. Machining input parameters provided by the machine tool builder cannot always meet the operator’s requirements. So, artificial neural network is introduced as an efficient approach to predict the values of performance parameters. In the present research, experimental investigations have been conducted to develop predictive models for the effect of input parameters on the responses such as Material Removal Rate, surface finish and kerf width. Material tested was HcHcr steel material. Molybdenum wires of diameters 0.18 mm were used for the WEDM machine. A feed forward back propagation artificial neural network (ANN) is used to model the influence of current, pulse-ON and pulse-OFF time on material removal rate, kerf width & surface roughness. Multilayer perception model has been constructed with feed forward back propagation algorithm using peak current, pulse-ON and pulse-OFF time as input parameters and MRR and surface roughness and kerf width as the output parameters. The predicted results based on the ANN model are found to be in very close agreement with the unexposed experimental data set. The modeling results confirm the feasibility of the ANN and its good correlation with the experimental results

Process Parameters Optimization of Resistance Spot Welding of Galvanized Steel Using Taguchi Method

Spot welding is a resistance welding process for joining metal sheets by directly applying opposite forces with pointed tips. The current and the heat generation are localized by the form of electrode. The amount of heat produced is a function of current, time and resistance between the work pieces. The present work attempts experimental investigations to study influence of important process parameters of resistance spot welding on weld strength, current and cycle time are varied at three different levels for different thickness and manufactured specimens are tested for weld strength.. Experiment have been conducted as per Taguchi method and fixed the levels for the parameters Analysis of variance (ANOVA) and F-test has been used for determining most significant parameters affecting the spot weld parameters

Using principal component analysis to develop performance indicators in professional rugby league

Previous research on performance indicators in rugby league has suggested that dimension reduction techniques should be utilised when analysing sporting data sets with a large number of variables. Forty-five rugby league team performance indicators, from all 27 rounds of the 2012, 2013 and 2014 European Super League seasons, collected by Opta, were reduced to 10 orthogonal principal components with standardised team scores produced for each component. Forced-entry logistic (match outcome) and linear (point’s difference) regression models were used alongside exhaustive chi-square automatic interaction detection decision trees to determine how well each principle component predicted success. The 10 principal components explained 81.8% of the variance in point’s difference and classified match outcome correctly ~90% of the time. Results suggested that if a team increased “amount of possession” and “making quick ground” component scores, they were more likely to win (β = 15.6, OR = 10.1 and β = 7.8, OR = 13.3) respectively. Decision trees revealed that “making quick ground” was an important predictor of match outcome followed by “quick play” and “amount of possession”. The use of PCA provided a useful guide on how teams can increase their chances of success by improving performances on a collection of variables, instead of analysing variables in isolation

Assessing group-based changes in high-performance sport. Part 1: null hypothesis significance testing and the utility of p values

The role of a strength and conditioning coach (SCC) has evolved over the last 10 years to accommodate the large influx of data now available. As such, today’s SCC must extend their skill set to include data analysis, understanding the validity and utility of p values, effect sizes, confidence intervals, and terms such as the smallest worthwhile change, and minimal difference. The aim of part one of this two-part review is to define and discuss the utility of null hypothesis significance testing (NHST), p values, and error rates. In part two, we introduce effect sizes, measures of variability, and confidence intervals, culminating in recommendations as to which may be the most viable options within the context of performance-based sport, and thus potential methods to report group-based changes

Assessing group-based changes in high-performance sport. Part 2: effect sizes and embracing uncertainty through confidence intervals

Today’s strength and conditioning coach must extend their skill set to include data analysis, understating the validity and utility of p values, effect sizes, confidence intervals, and terms such as the smallest worthwhile change, and minimal difference. The aim of part two of this two-part review is to now build on our discussion of null hypothesis significance testing (covered in part one), and introduce effect sizes, measures of variability, and confidence intervals, culminating in recommendations as to which may be the most viable options within the context of performance-based sport, and thus potential methods to report group-based changes. This paper has a series of worked examples to aid the reader

Determining unstable game states to aid the identification of perturbations in football

Alternative approaches to the reductionist method for analysing football are needed to better understand factors typically not considered, for example off the ball runs by teammates. The dynamical systems approach, where the complex relationships between players is emphasised, predicts that goal scoring opportunities are preceded by instability in the balance between the two teams’ behaviours. The aim was to create operational definitions for determining unstable game states to facilitate the identification of perturbations, that is the causes of instability. Validity tests involving four English Premier League (EPL) football coaches and two performance analysts and subsequent reliability tests established five unstable game states; penalty box possession, counter attack, ratio of attacking to defending players, successful cross and successful shot. Eighteen EPL matches were analysed to present exemplar statistics for three teams of different standard (based on final league position) suggesting that teams create unstable situations differently, likely due to individual player characteristics, with home advantage and opposition strength effects, suggesting this may be a component of what constitutes a performance indicator for a team. Future studies need to consider individual player actions that create instability as well as provide objective measures that substantiate findings

Team performance indicators that predict match outcome and points difference in professional rugby league

Performance indicators allow for the objective quantification of performance, however, limited PI research for professional rugby league exists. Therefore, this paper assessed 24 relative PIs (home value minus away) from all 27 rounds of the 2012, 2013 and 2014 European Super League seasons, collected by Opta, amounting to 567 matches. Backwards logistic (match outcome) and linear (points difference) regression models were used alongside exhaustive Chi-Square Automatic Interaction Detection decision trees to identify performance indicators (PIs) and key performance indicators. Teams had a higher chance of winning and would gain more points when they scored first (OR = 1.6, β = 2.4) and increased completed sets (OR = 1.2, β = 1.2) by one unit. Conversely, teams had a lower chance of winning when they increased scoots (OR = 0.9, β = −0.2). However, some PIs which were thought to be important (as identified by previous literature) were removed from the analysis thus calling into question the appropriateness of stepwise methods. Future research may consider utilising dimension reduction techniques when analysing large data-sets that encompass multiple variables

The attacking process in football: a taxonomy for classifying how teams create goal scoring opportunities using a case study of Crystal Palace FC

Purpose: Whilst some studies have comprehensively described the different features associated with the attacking process in football they have not produced a methodology of practical use for performance enhancement. This study presents a framework of comprehensive and meaningful metrics to objectively describe the attacking process so that useful performance profiles can be produced. Methods: The attacking process was categorized into three independent situations, no advantage (stable), advantage, and unstable (potential goal scoring opportunity) situations. Operational definitions for each situation enhanced their reliability and validity. English Premier League football matches (n = 38) played by Crystal Palace Football Club in the 2017/2018 season were analyzed as an exemplar. Results: Crystal Palace FC created a median of 53.5 advantage situations (IQR = 16.8) and 23 unstable situations (IQR = 8.8) per match. They frequently utilized wide areas (Median = 21.5, IQR = 9.8) to progress, but only 26.6% resulted in unstable situations (Median = 6.0, IQR = 3.8), the lowest rate compared to the other advantage situations. Conclusion: This classification framework, when used with contextual factors in a multi-factorial manner, including individual player contributions, will provide practically useful information for applied practice. This approach will help close the so called theory-practice gap and enable academic rigor to inform practical problems