A Finite Element Approach to Conduct Machinability Studies on Age-Hardened AA6061 Matrix Hybrid Composites

AA6061, a popular structural material, has found widespread usage in the automotive and aerospace domains. The current work explored the effect of the improvement of mechanical properties on the machinability of AA6061 through finite element analysis. Three compositions of AA6061 containing 2 wt.% graphite and 0, 2, 4 wt.% granite dust were fabricated by stir casting.  In the current work, a finite element model of a slab milling cutter with eight teeth was designed with high-speed steel (HSS) as the tool material. The LS-DYNA module of ANSYS was used for simulation of the milling operation, selecting two peripheral speeds for the cutter during the machining of the workpiece. Surface milling was carried out on the cast slabs of the three compositions to study chip formation. At higher cutting speeds, there was an increase in the von Mises stress as well as material deformation. An increase in the weight fraction of the ceramic fillers led to a corresponding increase in the von Mises stress and material deformation. The experimental results from face milling of the three compositions showed that the surface roughness increased with an increase in the content of ceramic fillers and a decrease in chip size

Analysis on Factors Causing Project Delays in Road and Highways Sector in India Using Relative Ranking Index Technique

On-time completion of road infrastructure projects is a critical goal. Whenprojects were not completed on schedule and real construction progress isslower than expected, the inconvenience and disruption to business accessincreases. On time completion is linked to economic and social welfare,as well as safety. Construction delays continue to be a typical occurrence,despite the need of prompt completion.A literature study is conducted in this context in order to learn more aboutthe causes and factors that contribute to delays. Following a thoroughreview of the literature, it was determined that a questionnaire survey isthe most effective and trustworthy way for gathering information about thecauses and quantifying delays caused by emergent factors. The RelativeImportance Index (RII) method was used to analyze the data, and thereasons for the delay were prioritized according to their importance. Thisstudy focuses on the emergent concerns/causes and reasons of concernin road infrastructure projects, as well as how to priorities these issuessequentially during the planning stage. This study survey can assistconstruction companies doing business in India in understanding theessential or sensitive issues that require special attention in order to conducttheir businesses smoothly in this country while employing appropriateproject management practices

A Finite Element Approach to Conduct Machinability Studies on Age-Hardened AA6061 Matrix Hybrid Composites

AA6061, a popular structural material, has found widespread usage in the automotive and aerospace domains. The current work explored the effect of the improvement of mechanical properties on the machinability of AA6061 through finite element analysis. Three compositions of AA6061 containing 2 wt.% graphite and 0, 2, 4 wt.% granite dust were fabricated by stir casting.  In the current work, a finite element model of a slab milling cutter with eight teeth was designed with high-speed steel (HSS) as the tool material. The LS-DYNA module of ANSYS was used for simulation of the milling operation, selecting two peripheral speeds for the cutter during the machining of the workpiece. Surface milling was carried out on the cast slabs of the three compositions to study chip formation. At higher cutting speeds, there was an increase in the von Mises stress as well as material deformation. An increase in the weight fraction of the ceramic fillers led to a corresponding increase in the von Mises stress and material deformation. The experimental results from face milling of the three compositions showed that the surface roughness increased with an increase in the content of ceramic fillers and a decrease in chip size

Migrating Ingested Foreign Body of the Upper Aerodigestive Tract with Resultant Septic Shock : Case report and literature review

Complications due to foreign body ingestion are rare; however, if present, these can cause significant morbidity to the patient. An overlooked ingested foreign body could present as an emergency and may prove fatal. We present a case of an accidentally ingested foreign body with delayed presentation, which migrated to the neck and produced a cervical abscess presenting as septic shock. The patient required prompt stabilisation followed by surgical intervention. The patient’s vital signs returned to normal on the second post-operative day, and he was discharged the following day

Performance Evaluation of Homogeneous Charge Compression Ignition Combustion Engine â A Review

The development of HCCI combustion technology has been drawing a great deal of attention from researchers. This survey explains ongoing research methodologies and results. HCCI combustion, other than conventional combustion, is purely based on chemical kinetics. At present the automobile sector faces the problem of emissions and needs to develop clean technologies. However, HCCI operation still has issues such as ignition control, combustion phasing control, operating range control, cold start, and UHC (unburned hydrocarbon) and CO (carbon monoxide) emissions. The challenge is to overcome these problems without compromising other engine parameters and performance. For HCCI, the mixture preparation is especially important, while the compression ratio, IVC (inlet valve closure) timing, inlet pressure, inlet temperature and EGR play a very prominent role in controlling it. This paper will go through a detailed discussion of all the above conditions

Progress of auxetic and semi-auxetic materials

Auxetic materials with negative Poisson\u27s ratios, display the unique behavior owing to their micro-structure or geometrical build. Auxetic materials resist deformities when subjected to uniaxial, biaxial, and shearing stresses. Cellular based materials are known for their excellent impact and shock energy absorption. When foams are incorporated with auxetic geometry, their impact energy absorption increases. Combination of auxetic materials with conventional materials yield semi-auxetic materials. Ideally, layered structures where facing materials are metallic sheets sandwiching polymeric foam cores are popular. The auxetic materials can be combined with conventional materials to obtain P-N-P and N-P-N semi-auxetic sandwiched structures with diverse potential in several applications like automotive, aerospace, sports equipment, and protective armors

Programmed Allee Effect in Bacteria Causes a Tradeoff Between Population Spread and Survival

Dispersal is necessary for spread into new habitats, but it has also been shown to inhibit spread. Theoretical studies have suggested that the presence of a strong Allee effect may account for these counterintuitive observations. Experimental demonstration of this notion is lacking due to the difficulty in quantitative analysis of such phenomena in a natural setting. We engineered Escherichia coli to exhibit a strong Allee effect and examined how the Allee effect would affect the spread of the engineered bacteria. We showed that the Allee effect led to a biphasic dependence of bacterial spread on the dispersal rate: spread is promoted for intermediate dispersal rates but inhibited at low or high dispersal rates. The shape of this dependence is contingent upon the initial density of the source population. Moreover, the Allee effect led to a tradeoff between effectiveness of population spread and survival: increasing the number of target patches during dispersal allows more effective spread, but it simultaneously increases the risk of failing to invade or of going extinct. We also observed that total population growth is transiently maximized at an intermediate number of target patches. Finally, we demonstrate that fluctuations in cell growth may contribute to the paradoxical relationship between dispersal and spread. Our results provide direct experimental evidence that the Allee effect can explain the apparently paradoxical effects of dispersal on spread and have implications for guiding the spread of cooperative organisms

Gambaran Pelaksanaan Problem-Based Learning Pada Mahasiswa Program Studi Pendidikan Dokter Fakultas Kedokteran Dan Ilmu Kesehatan Universitas Jambi

Background: Problem-Based Learning (PBL) is a new learning strategy that is focused on students, where they learn based on problems. Faculty of Medicine and Health Sciences UNJA (FKIK UNJA) have implemented PBL as a learning strategy in the Competence based Curriculum since 2007, however, there are no studies that measure the implementation of PBL based on its four theories in FKIK UNJA. Methods: This descriptive cross-sectional study design was conducted in April-May 2014 in FKIK UNJA. The number of respondents are 184 students from the class of 2010, 2011 and 2012. This research employed a questionnaire developed by Romauli et al. Then the average analysis is utilized to obtain the level of implementation of PBL based on the four theories. Results: The implementation level of PBL in FKIK UNJA that based on learning constructive, independent, collaborative and contextual was moderate (1,94). The implementation level of constructive learning process based on class of 2010, 2012 was high (2,02 and 2,13) and the class of 2011 was moderate (1,98). The implementation level of self-learning process based on the class of 2010, 2011 and 2012 was moderate (1,89; 1,87; 1,96). The implementation level of collaborative learning based on the class of 2010, 2011 was high (2,16 and 2,09) and the class of 2011 was moderate (1,97). The implementation level of contextual learning based on the class of 2010, 2011, and 2012 was moderate (1,78; 1,80; 1,82). Conclusions: The implementation of PBL on students of Medical Education FKIK UNJA in each class and all students, have stimulated students to develop their knowledge, stimulate control of the learning process in the student itself, stimulate the interaction between students and stimulate the learning process which reflects the situation and environment, where the knowledge will be used

Needle(s) in the Haystack – Synchronous Multifocal Tumor Induced Osteomalacia

This is the author accepted manuscript. The final version is available from Endocrine Society via http://dx.doi.org/10.1210/jc.2015-3854MG is supported by the NIHR Cambridge Biomedical Research Centre