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

Timing and spectral changes of the Be X-ray transient EXO 0531-6609.2 through high and low state

We report on spectral and timing analysis of BeppoSAX data of the 13.6 s period transient X-ray pulsar EXO 0531-6609.2. Observations were carried out in March 1997 and October 1998, catching the source during a high and a low emission state, respectively. Correspondingly, the X-ray luminosity is found at a level of 4.2x10^37 erg/s and 1.5x10^36 erg/s in the two states. In the high state the X-ray emission in the energy range 1-100 keV is well fitted by an absorbed power-law with photon index Gamma ~1.7 plus a blackbody component with a characteristic temperature of ~3.5 keV. Moreover, we find an evidence of an iron emission at ~6.8 keV, typical feature in this class of sources but never revealed before in the EXO 0531-6609.2 spectrum. In the low state an absorbed power-law with Gamma ~0.4 is sufficient to fit the 1-10 keV data. During BeppoSAX observations EXO 0531-6609.2 display variations of the pulse profile with the X-ray flux: it showed single peaked and double peaked profiles in the low and high state, respectively. Based on these two observations we infer a spin-up period derivative of -(1.14+/-0.08)x10^-10 s/s. By comparing these with other period measurements reported in literature we find an alternating spin-up and spin-down behaviour that correlates well with the X-ray luminosity.Comment: 6 pages, 8 figures, A&

1H0419-577: a two-state Seyfert Galaxy?

The preliminary results of the BeppoSAX observation of the radio-quiet AGN 1H0419-577 are presented. Despite its broad line optical spectrum, the intermediate X-ray spectrum (i.e. 2--10 keV) is flatter than typically observed in Seyfert 1s and no iron line is significantly detected. Even more intriguingly, a 1992 ROSAT pointed observation suggests a dramatic (~ 1) change in the spectral shape for E < 2 keV. Such behavior is briefly discussed in the framework of our current understanding of Comptonization scenarios in the nuclear regions of radio-quiet AGN.Comment: 4 pages, Latex, 4 Postscript figures, `espcrc2.sty included, to appear in the Proceedigns of the Workshop "The active X-ray sky: results from Beppo-SAX and RXTE

Treatment of Tuberculosis in Complex Emergencies in Developing Countries: A Scoping Review

Almost 172 million people live in complex emergencies globally resulting from political and/or economic instability. The provision and continuity of health care in complex emergencies remain a significant challenge. Health agencies are often hesitant to implement tuberculosis programmes in particular because its treatment requires a longer commitment than most acute diseases. However, not treating tuberculosis promptly increases mortality and untreated tuberculosis further increases the incidence of tuberculosis. Given that complex emergencies are increasing globally, there is an urgent need to analyse the available evidence to improve our understanding of how best to deliver tuberculosis programmes in such settings. Using a scoping review method, we selected and analysed fifteen studies on tuberculosis programmes in complex emergencies. We found that despite the challenges, tuberculosis programmes have been successful in complex emergencies. We identified seven cross-cutting factors that were found to be important: service providers and treatment regime, training and supervision, donor support, adherence, leadership and coordination, monitoring, and government and community support. In general, programmes showed greater creativity and flexibility to adapt to the local conditions and at times, it also meant diverting from the WHO guidelines. We identify areas of further research including the need to study the effectiveness of programmes that divert from the WHO guidelines and their implication on drug resistance

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

Polarization Independent Optical Coherence Tomography

Optical coherence tomography (OCT) is a well established imaging modality for high-resolution three-dimensional imaging in clinical settings. While imaging, care must be taken to minimize the imaging artifacts related to the polarization differences between the sample and the reference signals. Current OCT systems adopt complicated mechanisms, such as the use of multiple detectors, polarization-maintaining fibers, polarization controllers to achieve polarization artifacts free sample images. Often the polarization controllers need readjustment which is not suitable for clinical settings. In this work, we demonstrate a simple approach that can minimize the polarization-related artifacts in the OCT systems. Polarization artifact-free images are acquired using two orthogonally polarized reference signals where the orthogonal polarization is achieved using a Faraday mirror. In the current approach, only a single detector is required which makes the current approach compatiblewith swept-source or camera-basedOCT systems. Furthermore, no polarization controllers are used in the system which increases the system stability while minimizing the artifacts related to the sample birefringence, polarization change due to the sample scattering, and polarization change due to the optical fiber movements present in the system