Effect of Die and Punch Radius on Springback of Stainless Steel Sheet Metal in the Air V-Die Bending Process

This paper focuses on the effect of the die and punch radii on the springback in the air V-die free bending process of stainless steel sheet metal. The experiment was performed on sheet metal using various die and punch radius values while their springback behavior was observed. The design of experiment approach was used in these experiments using the full factorial and analysis of variance methods to identify whether or not the die and punch radii are significant input parameters in predicting springback. From the statistical analysis, it shows that the die and punch radius parameters are significant factors contributing to the springback effect in the V-die bending of stainless steel sheet metal at the significance level of 0.05 because their p-value is less than 0.05. The results from the experiments showed that springback is affected by the die and punch radius values in the air V-bending experiments. From this analysis, it can be concluded that the springback values can be decreased by decreasing the values of the die and punch radii. In the air V-die bending process, the punch radius is the most important factor to be considered. The experimental method agreed well with the design of experiment results

ABCD² risk score does not predict the presence of cerebral microemboli in patients with hyper-acute symptomatic critical carotid artery stenosis

ABCD² risk score and cerebral microemboli detected by transcranial Doppler (TCD) have been separately shown to the predict risk of recurrent acute stroke. We studied whether ABCD² risk score predicts cerebral microemboli in patients with hyper-acute symptomatic carotid artery stenosis. We studied 206 patients presenting within 2 weeks of transient ischaemic attack or minor stroke and found to have critical carotid artery stenosis (≥50%). 86 patients (age 70±1 (SEM: years), 58 men, 83 Caucasian) had evidence of microemboli; 72 (84%) of these underwent carotid endarterectomy (CEA). 120 patients (age 72±1 years, 91 men, 113 Caucasian) did not have microemboli detected; 102 (85%) of these underwent CEA. Data were analysed using X2 and Mann-Whitney U tests and receiver operating characteristic (ROC) curves. 140/206 (68%: 95% CI 61.63 to 74.37) patients with hyper-acute symptomatic critical carotid stenosis had an ABCD2 risk score ≥4. There was no significant difference in the NICE red flag criterion for early assessment (ABCD² risk score ≥4) for patients with cerebral microemboli versus those without microemboli (59/86 vs 81/120 patients: OR 1.05 ABCD² risk score ≥4 (95% CI 0.58 to 1.90, p=0.867)). The ABCD² risk score was <4 in 27 of 86 (31%: 95% CI 21 to 41) embolising patients and in 39 of 120 (31%: 95% CI 23 to 39) without cerebral microemboli. After adjusting for pre-neurological event antiplatelet treatment (APT), area under the curve (AUC) of ROC for ABCD2 risk score showed no prediction of cerebral microemboli (no pre-event APT, n=57: AUC 0.45 (95% CI 0.29 to 0.60, p=0.531); pre-event APT, n=147: AUC 0.51 (95% CI 0.42 to 0.60, p=0.804)). The ABCD² score did not predict the presence of cerebral microemboli or carotid disease in over one-quarter of patients with symptomatic critical carotid artery stenosis. On the basis of NICE guidelines (refer early if ABCD² ≥4), assessment of high stroke risk based on ABCD² scoring may lead to inappropriate delay in urgent treatment in many patients

THE DEVELOPMENT OF COMPUTATIONAL MODEL THROUGH

Reverse engineering is a process of capturing the geometry by existing physical objects and used the data obtained as a foundation for re-designing or designing something new. Laser scanners are commonly used since they can be a sample of threedimensional range images fast and very accurately relative to other technologies.The complexity of the process to re-modelling the objects is very obvious since there-shaping of the object is more to surface consideration and not solid modelling.This paper employs and compares two methods of reverse engineering. First, conventional method is used where the parts of a car side mirror are drawn from direct measurement. Second, the detail drawings of the same parts are generated through three-dimensional scanning software. For the conventional method, direct measurements are obtained using a vernier calliper, ruler and micrometer. For the later approach, three-dimensional scanning software is used, where the side mirror and its components are scanned to obtain the initial feature, which later on is refined to achieve an accurate computational model. Based on the final computational model, both methods are compared and analysed. This paper is aimed to exhibit a computer aided reverse engineering approach in modelling a product through both methods. Acomprehensive methodology is presented through a case study approach

Parameter optimization of debinding injection moulded Ti-6Al-4V mix with palm stearin and polyethylene

Debinding process of injection moulded Ti-6Al-4V feedstock was divided into two parts: solvent debinding process to eliminate palm stearin (PS) and thermal pyrolysis to eliminate polyethylene (PE). Solvent debinding process used heptane at optimum temperature, 60°C to remove PS binder completely as temperature is the only parameter that can be optimized. Thermal pyrolysis parameters for removal of PE binder from the injected 65vol% Ti-6Al-4V feedstock have been optimized by using Taguchi method. Heating rate, temperature and time were the selected factors during experiment to be applied in the L9(34) Taguchi orthogonal array (OA) to find the best set of parameters to produce highest density of brown part. Thermal pyrolysis process was done at optimum parameters: heating rate: 5°C/min; temperature: 510°C; and time: 90 minutes. Analysis of Variance (ANOVA) was employed to find the best signal to noise ratio (S/N) to express the contribution of the factors towards quality characteristic. Based on the results, heating rate has the greatest contribution (54.63%), followed by duration time of thermal pyrolysis (24.40%) and temperature (19.25%)

Prediction of Cutting Force in End Milling of Inconel 718

This paper presents the effect of cutting parameters on the cutting force when machining Inconel 718. Response surface methodology (RSM) was used in the experiment, and a Box–Behnken design was employed to identify the cause and effect of the relationship between the four cutting parameters (cutting speed, feed rate, depth of cut and width of cut) and cutting force. The ball-nose type of end mill with donwmill approach was maitained througout the experiment. The forces were measured using Kistler dynamometer during straight line machining strategy. The result shows that the radial depth of cut was the dominating factor controlling cutting force, it was followed by axial depth of cut and feed rate. The prediction cutting force model was developed with the average error between the predicted and actual cutting force was less than 3

The analysis of grid independence study in continuous disperse of MQL delivery system

A sustainable cutting method of Minimum Quantity Lubricant (MQL) was introduced to promote lubrication effect and improve machinability. However, its performances are very dependent on the effectiveness of its mist to penetrate deep into the cutting zone. Optimizing the MQL system requires massive experimental work that increases cost and time. Therefore, this study conducts Computational Fluid Dynamic (CFD) analysis using ANSYS Fluent and focuses on the grid independence study in dispersed-continuous phase of MQL delivery system. The main aim is to identify the best mesh model that influences the accuracy of the CFD model. The analysis proposed two different unstructured grid cell elements of quadrilateral and triangular that were only applicable for 2-dimensional fluid flow in CFD. The unstructured grid was controlled with three different mesh quality factors such as Relevance Center, Smoothing, and Span Angle Center at coarse /low, medium, and fine /high. The results showed that the best mesh quality for quadrilateral was at 60,000 nodes number and coarse mesh, whereas the triangular was at 90,000 nodes number and coarse mesh. Both combinations resulted the most consistent and reliable result when compared with past studies. However, this study decided to choose quadrilateral cell element with 60,000 nodes number and coarse mesh as it is considered to be sufficient to provide accurate and reliable result as well as practical in terms of computational time for the MQL model in CFD analysis

Giant Merkel cell carcinoma of the eyelid: a case report and review of the literature

Merkel cell carcinoma (MCC) is a rare cutaneous tumor and cases located in the eyelid have been described, but still its rarity may lead to difficulty in diagnosis and delay in treatment. A 51-year-old female patient that presented with large lesions in the eyelid underwent surgery after the diagnosis of acute chalazion. Following respiratory distress secondary to pulmonary metastasis, the patient's condition deteriorated and was not fit for complete excision treatment. Histopathological investigation of the biopsies, taken from the tumor, revealed that it was undifferentiated small cell carcinoma. Our aim with this paper is to point out that more cases should be reported for more effective diagnosis, histopathological study, clinical investigation, treatment and prognosis of this specific neoplasm

The national portfolio for postgraduate family medicine training in South Africa : a descriptive study of acceptability, educational impact, and usefulness for assessment

Background: Since 2007 a portfolio of learning has become a requirement for assessment of postgraduate family medicine training by the Colleges of Medicine of South Africa. A uniform portfolio of learning has been developed and content validity established among the eight postgraduate programmes. The aim of this study was to investigate the portfolio's acceptability, educational impact, and perceived usefulness for assessment of competence. Methods: Two structured questionnaires of 35 closed and open-ended questions were delivered to 53 family physician supervisors and 48 registrars who had used the portfolio. Categorical and nominal/ordinal data were analysed using simple descriptive statistics. The open-ended questions were analysed with ATLAS.ti software. Results: Half of registrars did not find the portfolio clear, practical or feasible. Workshops on portfolio use, learning, and supervision were supported, and brief dedicated time daily for reflection and writing. Most supervisors felt the portfolio reflected an accurate picture of learning, but just over half of registrars agreed. While the portfolio helped with reflection on learning, participants were less convinced about how it helped them plan further learning. Supervisors graded most rotations, suggesting understanding the summative aspect, while only 61% of registrars reflected on rotations, suggesting the formative aspects are not yet optimally utilised. Poor feedback, the need for protected academic time, and pressure of service delivery impacting negatively on learning. Conclusion: This first introduction of a national portfolio for postgraduate training in family medicine in South Africa faces challenges similar to those in other countries. Acceptability of the portfolio relates to a clear purpose and guide, flexible format with tools available in the workplace, and appreciating the changing educational environment from university-based to national assessments. The role of the supervisor in direct observations of the registrar and dedicated educational meetings, giving feedback and support, cannot be overemphasized

Orthostatic hypotension: clinical review and case study

Transient loss of consciousness (TLOC) accounts for 3% of all attendance in emergency departments within the UK. More than 90% of TLOC presentations are due to epileptic seizures, psychogenic seizures or syncope. However, in England and Wales in 2002, it was estimated that 92000 patients were incorrectly diagnosed with epilepsy, at an additional annual cost to the NHS of up to £189 million. This article will reflect on the case study of a 54-year-old female patient who presented with a possible TLOC, and had a background of long-term depression. Differential diagnoses will be discussed, but the article will focus on orthostatic hypotension. Being diagnosed with this condition is independently associated with an increased risk of all-cause mortality. Causes of orthostatic hypotension and the pathophysiology behind the condition will be discussed, highlighting the importance of obtaining an accurate clinical history. This is extremely pertinent if a patient collapses in an NHS setting and this is witnessed by nurses because they can contribute to the history of the type of collapse, to aid diagnosis and correct treatment. In addition, nurses have a valuable role to play in highlighting polypharmacy to doctors, and non-medical prescribers, as a contributing factor to orthostatic hypotension is polypharmacy. It is therefore important to accurately distinguish TLOC aetiology, not only to provide appropriate management, but to also identify patients at risk of morbidity/mortality related to underlying disease.N/