Additive Manufacturing Of Al 4047 And Al 7050 Alloys Using Direct Laser Metal Deposition Process

Additive manufacturing (AM) of metals is finding numerous applications in automotive and aerospace industry. In 21st century, aluminum is second to steel in automotive sector, because of its high strength to weight ratio. In current era, casted components of Al-Si alloy and high strength Al 7xxx series alloys are being used from low load to high load components. The primary study of this research was to achieve the defect free deposition of Al-Si and Al 7050 alloy. Al-Si alloys samples have been manufactured at lab scale using various additive manufacturing processes, but so far there is no literature available to investigate the feasibility of fabricating Al-Si alloy component for automotive component applications using Direct Laser Metal Deposition (LMD) technique. This research deals with the practical challenges of building single wall and block deposition (cuboid shapes) of eutectic Al-Si alloy using direct laser metal deposition process for automotive applications. Microstructural investigation using optical and scanning electron microscopy confirms greater than 99% component density of as-deposited Al-11.2Si and Al 7050 sample. Tensile test sample extracted from Al-11.2Si deposit showed an impressive elongation of 9% with an ultimate tensile strength of 225 MPa. This investigation revealed that direct laser metal deposition could successfully print the eutectic Al-Si alloy bracket on shock tower hood without any distortion or bending. For Al 7050, parameter optimization (laser power, powder flow rate, and scanning speed) gets difficult with the presence of various low melting and boiling point alloying elements such as Zn, Mg etc. Microstructural characterization and microhardness test were performed and results showed microhardness of 100 HV of as-deposited sample and 128 HV after heat treatment. To cope with the issue of vaporization of second phase elements Mg and Zn, laser metal deposition of Al 7050 alloy powder coated with nickel was conducted using optimized parameters. Microstructural investigation using optical and electron microscopy revealed that the deposits are free from relevant defects such as porosity or lack of fusion. However, the added nickel was partially segregated in the inter-dendritic boundaries and formed brittle Al3Ni intermetallics. As a result, as-deposited Ni coated Al 7050 alloy showed almost no tensile ductility. Laser deposited samples were friction stir processed to refine and uniformly distribute Al3Ni particles in the α-Al matrix. Tensile test results revealed a good combination of yield strength (178 MPa), UTS (302 MPa), and 6% elongation of friction stir processed (FSP) samples. Post FSP heat treatment additionally improved both strength and elongation about 10%. Microstructural investigation revealed a systematic change of columnar to equiaxed dendrites from bottom to top of each deposited layer. Laser metal deposited Al 7050 alloy exhibits different composition with reduced Mg and Zn quantity than it was present in Al 7050 powder due to evaporation of Mg and Zn. This research also presents the technique to study ten different Al 7050 compositions in one coupon of 20 mm ×20 mm. Final compositions were measured using EDS to establish correlation between Mg content in feed powder and in laser deposited material. Microhardness showed linear increment trend with linear addition of Mg by weight percent. Formation of strengthening precipitates Al3Mg2 and MgZn2 were escalated with the linear addition of Mg from bottom to the top of the Al 7050 gradient sample. Vaporization curve showed that with the addition of more Mg, respective loss also increases as compared to loss of Mg happened in previous layer. Microhardness test revealed that with addition of Mg, microhardness increased from 94 HV to 154 of as-deposited and 110 HV to 190 of heat-treated Al 7050 gradient sample. This technique is very useful to develop new alloys by studying various compositions in one sample saving time and effort

Falsifiable Network Models. A Network-based Approach to Predict Treatment Efficacy in Ulcerative Colitis

This work is focused on understanding the treatment efficacy of patients with ulcerative colitis (UC) using a network-based approach. UC is one of two forms of inflammatory bowel disease (IBD) along with Crohn’s disease. UC is a debilitating condition characterized by chronic inflammation and ulceration of the colon and rectum. UC symptoms occur gradually rather than abruptly, and the degree of symptoms differs across UC patients. Only around 20% of all UC cases can be explained by known genetic variations, implying a more ambiguous aetiology that is yet not fully understood but is thought to involve a complex interplay between genetic and environmental factors. The available therapy for UC substantially reduces symptoms and achieves long-term remission. However, about one-third of UC patients fail to respond to anti-TNFα therapy and consequently develop long-term side effects due to medication. Non-response to existing antibody-based therapies in subgroups of UC patients is a major challenge and incurs a healthcare burden. Therefore, the disease markers for predicting therapy response to assist individualized therapy decisions are needed. To date, no quantitative computational framework is available to predict treatment response in UC. We developed a quantitative framework that uses gene expression data and existing biological background information on signalling pathways to quantify network connectivity from receptors to transcription factors (TF) that are involved in UC pathogenesis. Variations in network connectivity in UC patients can be used to identify responders and non-responders to anti-TNFα and anti-Integrin treatment. Our findings allow us to summarize the effect of small gene expression changes on the overall connectivity of a signalling network and estimate the effect this will have on the individual patients' responses. Estimating the network connectivity associated with varied drug responses may provide an understanding of individualized treatment outcomes. Our model could be used to generate testable hypotheses about how individual genes act together in networks to cause inflammation in UC as well as other immune-inflammatory diseases such as psoriasis, asthma, and rheumatoid arthritis

Proving Correctness for Pointer Programs in a Verifying Compiler

This research describes a component-based approach to proving the correctness of programs involving pointer behavior. The approach supports modular reasoning and is designed to be used within the larger context of a verifying compiler. The approach consists of two parts. When a system component requires the direct manipulation of pointer operations in its implementation, we implement it using a built-in component specifically designed to capture the functional and performance behavior of pointers. When a system component requires pointer behavior via a linked data structure, we ensure that the complexities of the pointer operations are encapsulated within the data structure and are hidden to the client component. In this way, programs that rely on pointers can be verified modularly, without requiring special rules for pointers. The ultimate objective of a verifying compiler is to prove-with as little human intervention as possible-that proposed program code is correct with respect to a full behavioral specification. Full verification for software is especially important for an agency like NASA that is routinely involved in the development of mission critical systems

Effect of plyometric training on sand versus grass on muscle soreness and selected sport-specific performance variables in hockey players

The purpose of this study was to compare the effects of a 4-week plyometric training on two different surfaces, sand and grass on muscle soreness and selected sport-specific performance variables in national level hockey players. Subjects were randomly divided into two groups- grass training group (N=20) and sand training group (N=20). After the baseline measurements of strength, endurance, balance, and agility, plyometric training was given for 4-weeks,three sessions per week. Muscle soreness was assessed at the end of each training session on a 7-point likert scale.Post-readings of strength, endurance, balance and agility were taken after the 4-week training programme. Data when compared after plyometric training revealed no significant changes between two groups (p>0.05), however players in the sand group experienced less muscle soreness (p<0.05) than grass group. There was significant improvement (p<0.05) seen in the tested variables in both groups after the training but no significant interaction was found between the two surfaces after the training. These findings suggest that short-term plyometric training on sand/non-rigid surface induces similar improvements in strength, endurance, balance and agility as on firm surface but induces significantly less muscle soreness. Hence, plyometric training on sand is viable option for coaches to enhance performance in athletes, while reducing risk of muscle soreness and damage

EFFECT OF A 6 WEEK AGILITY TRAINING PROGRAM ON LOWER BODY MUSCLE ELECTROMYOGRAPHY CHANGES OF INDIAN TAEKWONDO PLAYERS

Purpose: Taekwondo requires high level of agility, lower limb strength as it helps to improve performance in activities that require you to change direction quickly while keeping balance, strength, speed and body control. The purpose of the study was to determine the effect of a 6 week agility training program on lower body muscle electromyography changes. Methodology: 30 elite national level taekwondo players volunteered and were randomly assigned into two groups, group 1 (G1; n = 15) agility training group (mean age 19.60 ± 2.06 years; mean height 1.72 ± 0.08 m; mean mass 57. 94 ± 10. 27 kg) and group 2 (G2; n = 15) control group (mean age 20.13 ± 1.55; mean height 1.71 ± 0.07 m; mean mass 65.19 ± 16.87). Both agility training group and control group were assessed for electromyography of lower limb muscles by Noraxon Telemyo U.S.A., Inc.v3.1.10. Control group had followed their routine training schedule, and agility training group had performed agility training for 6 weeks. After 6 weeks of training post measures were taken. Result: Significant changes (p &lt; 0.05) were observed in average mean amplitude and maximum of the left biceps femoris muscle as well as some specific findings were observed. Conclusion: This program can be incorporated to improve overall performance in the athletes and can beneficial for athletes who require quick movements while performing their sport such as taekwondo.  Article visualizations

ELECTROMYOGRAPHIC CHANGES FOLLOWING SPRINT SPECIFIC PLYOMETRIC PROGRAM IN SPRINTERS

Purpose: The ability to reach a high running velocity over a short period of time is essential for sprinters. Sprinting requires appropriate muscle recruitment for an athlete to perform. The purpose of this study was to determine the effect of the sprint specific plyometric training on electromyographic (EMG) changes in sprinters. Methodology: 40 university sprinters volunteered and were randomly assigned into two groups, group 1 (G1; n=20) sprint specific plyometric training group(mean age 18.65±0.875; mean height 164.10±11.30 cm; mean mass 59.20±10.74 kg) and group 2 (G2; n= 20) control group (mean age 18.95±1.19; mean height 166.60±9.80 cm; mean mass 61.60±9.24 kg ). Both sprint specific plyometric training group and control group were assessed for neuromuscular activity of lower limb muscles by telemetric Noraxon TELEMYO U.S.A., Inc.v3.1.10 machine. Subjects in training group performed six weeks sprint specific plyometric protocol thrice a week. The EMG activities in the tibialis anterior (TA), vastus lateralis (VL), rectus femoris (RF), medial gastrocnemius (MG) and semitendinosis muscle (ST) were assessed pre and post training. Results: The results showed significant changes (p&lt;0.05) in the EMG activities for the mean amplitude of RF(rt), MG(lt), ST(rt) muscles and maximum periods of TA(rt), VL(rt), MG(lt) and ST(rt) muscles. Conclusion: The study demonstrates that the neuromuscular training program can increase the muscle recruitment to perform high intensity activities hence, can be recommended to coaches for athletes or individual.   Article visualizations

Case Studies on Variation Tolerant and Low Power Design Using Planar Asymmetric Double Gate Transistor

In nanometer technologies, process variation control and low power have emerged as the first order design goal after high performance. Process variations cause high variability in performance and power consumption of an IC, which affects the overall yield. Short channel effects (SCEs) deteriorate the MOSFET performance and lead to higher leakage power. Double gate devices suppress SCEs and are potential candidates for replacing Bulk technology in nanometer nodes. Threshold voltage control in planar asymmetric double gate transistor (IGFET) using a fourth terminal provides an effective means of combating process variations and low power design. In this thesis, using various case studies, we analyzed the suitability of IGFET for variation control and low power design. We also performed an extensive comparison between IGFET and Bulk for reducing variability, improving yield and leakage power reduction using power gating. We also proposed a new circuit topology for IGFET, which on average shows 33.8 percent lower leakage and 34.9 percent lower area at the cost of 2.8 percent increase in total active mode power, for basic logic gates. Finally, we showed a technique for reducing leakage of minimum sized devices designed using new circuit topology for IGFET

Assessment of Suspending Properties of Katira Gum: Formulation and Evaluation of Nimesulide Suspension

There are several hydrophilic polymers that have been employed as suspending agents in pharmaceutical suspensions due to their ability to form colloidal gel in aqueous medium. In the present study, katira gum obtained from the bark of Cochlospermum religiosum has been evaluated as suspending agent in nimesulide suspension and compared with acacia gum at concentration of 1-5%. Sedimentation volume, rheology, particle size, degree of flocculation and in-vitro drug release were employed as assessment parameters. The result showed that at all concentrations, katira gum higher suspending capability compared acacia gum. The sedimentation volume was found to increase from 0.36 to 1 (A1-A3) and 0.26 to 0.56 (B1-B3). The viscosity of suspensions (A1 and A2) containing gum katira as suspending agent was found to be 1.35 and 2.4 centipoise and 0.63- 1.05 centipoise (B1- B3). Plots between shear stress and rate of shear were plotted using different concentrations indicates the obedience to newtonian behaviour. Degree of flocculation of gum katira and gum acacia suspension was established to be 1.69 and 1.05 respectively

A Meta Analysis on Cardiac Vascular Disease with Obesity

Increasing evidence suggests that inflammatory and immunological factors present in the general population play a role in the pathogenesis of cardiovascular disease in RA. More than that, RA is treated with a wide range of drugs, many of which have the potential to alter cardiovascular function. Non-steroidal anti-inflammatory medicines (NSAIDs) have been linked to an increased risk, whereas some treatments, like methotrexate and TNF inhibitors, have been linked to a reduced risk. Cardiac catheterization is just one of several possible procedures that can be done on the heart. More than a million people in the United States get cardiac catheterization each year. [1] Any time a surgeon makes incisions into a patient, they must be ready for the possibility of complications, whether they arise from the patient or the surgery itself. Fortunately, the prevalence of these issues has decreased considerably in recent years thanks to developments in cardiac catheterization equipment, advances in the experience of the operators, and the introduction of novel methods. The term "cardiac catheterization" can refer to either a right heart or a left heart catheterization, or both. Depending on the patient\u27s condition, interventional cardiologists can do either diagnostic or therapeutic operations. The dangers and difficulties that can arise during a diagnostic cardiac catheterization are briefly discussed in this article