Finite element modelling and simulation of metal flow in bulge forming

The research and application of finite element methods in the area of material processing has increased rapidly in recent years. Application of FEM is reported in the processing of most engineering materials including new materials like metal matrix composites. In metal forming, FEM is mostly applied to conventional forming situations like forging and upsetting, extrusion, drawing, rolling, sheet metal forming, casting and moulding and machining Most of these forming operations are also well analysed by theories of plastic deformation like limit theorems, slip-line field theory etc. In contrast, new and unconventional metal forming cases, which are often very complex, are relatively under-analysed either by the theoretical methods mentioned above or by numerical methods like finite element. This work is mainly devoted to computer simulation and study of one of the unconventional metal forming process called bulge forming. There are various type of industrial products made by bulge forming process. In some processes the main forming load is the hydrostaic pressure on the surface of the blank plate or shell. While in others, an in-plane compressive load is also applied simultaneously with the pressure load. Depending on the initial blank shape and final product shape, the simultaneous loading case becomes a complex forming situation. This project has simulated the later category of bulge forming by finite element method. Number of such cases were simulated to cover initial blank shape viz flat circular plate, flat rectangular plate and initially curved shell In the latter category axisymmetric expansion of tubes, T-branch forming from straight cylindrical tubes and forming of box-sectioned elbow from cylindrical tubes were simulated. In each case different loading and friction conditions were tried Distribution of stress and strain were studied for all the cases Companson were made between comparable forming conditions. Response of certain parameter with respect to the changes of different forming variables of the process were also studied for most of the simulated cases. In case of the bulging of flat circular plate, optimum forming condition were identified for different objective criteria Taguchi parameter design method was applied to transform the above optimum values to practicable engineering values. All the simulations were carried out using well known commercial finite element packages. Both static frontal solvers and explicit dynamic solvers were used for the simulations

Historical trends and future projection of climate at Dhaka city of Bangladesh

Dhaka, the capital city of Bangladesh is considered as one of the most vulnerable cities of the world to climate change. A study has been carried out to assess the historical changes as well as future changes in the climate of Dhaka city in order to propose necessary mitigation and adaptation measures. Statistical downscaling model (SDSM) was used for the projection of future changes in daily rainfall and temperature and non-parametric trend analysis was used to assess the changes in rainfall, temperature and related extremes. The impacts of projected changes in climate on urban infrastructure and livelihood in Dhaka city was finally assessed to propose necessary adaptation measures. The study revealed that night time temperature in Dhaka city has increased significantly at a rate of 0.22ºC/decade in last fifty year, which is support to increase continually in the future. Different temperature related extreme events are also found to increase significantly in Dhaka. On the other hand, no significant change in rainfall or rainfall related extremes are observed. Therefore, it can be remarked that imminent impacts of climate change will be due to the increase in temperature and temperature related extremes. The public health and the water and energy supply are likely to be imminent affected sector in the city due to climate change

Selection of cemented carbide turning tools using EMF and optimization criteria

Tool life and quality of surface finish of the workpiece influence production rate and production cost. Cemented carbide tools have found wide application in the production arena of Bangladesh. In the absence of any testing facility in the country for the selection of cost-effective tools, poor quality carbide tools are frequently imported. A testing method and a selection criteria were developed for testing carbide tools of different shapes and sizes and for selecting the most cost-effective tool. For each tool cutting tests were performed to generate tool life data under different cutting conditions. Mild steel served as the work material. The relationship between tool life and cutting speed was developed using a curve-fitting software on a PC. From these relationships the values of the constants of the Taylor’s equation were determined. The cost equation was then derived for each tool for a given amount of work in a cutting speed range. Finally, the most cost-effective tool was selected on the basis of the relative location of the cost curves of the tools tested

Meditation as a Potential Therapy for Autism: A Review

Autism is a chronic neurodevelopmental disorder of unknown cause that affects approximately 1–3 percent of children and four times more boys than girls. Its prevalence is global and its social impact is devastating. In autism, the brain is unable to process sensory information normally. Instead, simple stimuli from the outside world are experienced as overwhelmingly intense and strain the emotional centers of the brain. A stress response to the incoming information is initiated that destabilizes cognitive networks and short-circuits adequate behavioral output. As a result, the child is unable to respond adequately to stimulation and initiate social behavior towards family, friends, and peers. In addition, these children typically face immune-digestive disorders that heighten social fears, anxieties, and internal conflicts. While it is critical to treat the physical symptoms, it is equally vital to offer an evidence-based holistic solution that harmonizes both their emotional and physical well-being as they move from childhood into adult life. Here, we summarize evidence from clinical studies and neuroscience research that suggests that an approach built on yogic principles and meditative tools is worth pursuing. Desired outcomes include relief of clinical symptoms of the disease, greater relaxation, and facilitated expression of feelings and skills, as well as improved family and social quality of life

Context Fear Conditioning in Down Syndrome Mouse Models: Effects of Trisomic Gene Content, Age, Sex and Genetic Background

Down syndrome (DS), trisomy of the long arm of human chromosome 21 (Hsa21), is the most common genetic cause of intellectual disability (ID). Currently, there are no effective pharmacotherapies. The success of clinical trials to improve cognition depends in part on the design of preclinical evaluations in mouse models. To broaden understanding of the common limitations of experiments in learning and memory, we report performance in context fear conditioning (CFC) in three mouse models of DS, the Dp(16)1Yey, Dp(17)1Yey and Dp(10)1Yey (abbreviated Dp16, Dp17 and Dp10), separately trisomic for the human Hsa21 orthologs mapping to mouse chromosomes 16, 17 and 10, respectively. We examined female and male mice of the three lines on the standard C57BL/6J background at 3 months of age and Dp17 and Dp10 at 18 months of age. We also examined female and male mice of Dp17 and Dp10 at 3 months of age as F1 hybrids obtained from a cross with the DBA/2J background. Results indicate that genotype, sex, age and genetic background affect CFC performance. These data support the need to use both female and male mice, trisomy of sets of all Hsa21 orthologs, and additional ages and genetic backgrounds to improve the reliability of preclinical evaluations of drugs for ID in DS

Bivariate flood frequency analysis using gumbel copula

A copula based methodology is presented in this study for bivariate flood frequency analysis over a station over a Kelantan river basin located in Northeast Malaysia. The joint dependence structures of three flood characteristics, namely, peak flow, flood volume and flood duration were modelled using Gumble Copula. Various univariate distribution functions of flood variables were fitted with observed flood variables to find the best distributions (eg. generalized pareto, log-normal, exponential, gamma distribution, weibull, gumbel, cauchy). The results of study revealed that different variable fits with different distributions and the correlation analysis among variables showed a strong association. Cumulative joint distribution functions (CDF) of peakflow and volume, peakflow and duration and volume and duration revealed that return period of joint return periods are much higher

Loss of correlations among proteins in brains of the Ts65Dn mouse model of down syndrome.

The Ts65Dn mouse model of Down syndrome (DS) is trisomic for orthologs of 88 of 161 classical protein coding genes present on human chromosome 21 (HSA21). Ts65Dn mice display learning and memory impairments and neuroanatomical, electrophysiological, and cellular abnormalities that are relevant to phenotypic features seen in DS; however, little is known about the molecular perturbations underlying the abnormalities. Here we have used reverse phase protein arrays to profile 64 proteins in the cortex, hippocampus, and cerebellum of Ts65Dn mice and littermate controls. Proteins were chosen to sample a variety of pathways and processes and include orthologs of HSA21 proteins and phosphorylation-dependent and -independent forms of non-HSA21 proteins. Protein profiles overall show remarkable stability to the effects of trisomy, with fewer than 30% of proteins altered in any brain region. However, phospho-proteins are less resistant to trisomy than their phospho-independent forms, and Ts65Dn display abnormalities in some key proteins. Importantly, we demonstrate that Ts65Dn mice have lost correlations seen in control mice among levels of functionally related proteins, including components of the MAP kinase pathway and subunits of the NMDA receptor. Loss of normal patterns of correlations may compromise molecular responses to stimulation and underlie deficits in learning and memory

Age exacerbates abnormal protein expression in a mouse model of Down syndrome.

The Ts65Dn is a popular mouse model of Down syndrome (DS). It displays DS-relevant features of learning/memory deficits and age-related loss of functional markers in basal forebrain cholinergic neurons. Here we describe protein expression abnormalities in brain regions of 12-month-old male Ts65Dn mice. We show that the magnitudes of abnormalities of human chromosome 21 and non-human chromosome 21 orthologous proteins are greater at 12 months than at ∼6 months. Age-related exacerbations involve the number of components affected in the mechanistic target of rapamycin pathway, the levels of components of the mitogen-activated protein kinase pathway, and proteins associated with Alzheimer\u27s disease. Among brain regions, the number of abnormalities in cerebellum decreased while the number in cortex greatly increased with age. The Ts65Dn is being used in preclinical evaluations of drugs for cognition in DS. Most commonly, drug evaluations are tested in ∼4- to 6-month-old mice. Data on age-related changes in magnitude and specificity of protein perturbations can be used to understand the molecular basis of changes in cognitive ability and to predict potential age-related specificities in drug efficacies. Neurobiol Aging 2017 May 10; 57:120-132