Stress analysis and fatigue life prediction of a wobble-plate

A five-stage compressor for compressing natural gas is being designed and evaluated. The compressor operates at 1500 rpm with natural gas pressure of 50 psi. This study examines deformation behavior, stress and strain distribution of the wobble plate component of the compressor. Fatigue loading on the wobble plate is computed from the reaction of compressed gas in each of the five cylinders. The highest pressure in the 5th cylinder is 3000 psi. The calculated stress evolution per revolution of the wobble plate is utilized to predict the fatigue lives of the wobble plate. The fatigue life prediction is performed using Brown-Miller algorithm with Morrow mean stress correction method. Results show that the stress is concentrated in the vicinity of the contact region between the guide plate and the polymer guide ball. The highest stress in the wobble plate and the polymer guide ball is 160.4 MPa and 127.8 MPa respectively. The corresponding predicted fatigue life of the wobble plate is 8x108 cycles. A higher stress gradient in the guide ball (max von Mises stress is 3.3 GPa) is predicted when a harder steel ball is employed. This is due to high stiffness of the mating plate/ball surfaces

Book Review: Tiger Economies under Threat: A Comparative Analysis of Malaysia’s Industrial Prospects and Policy Options, by Shahid Yusuf and Kaoru Nabeshima, Washington D.C.: The World Bank, 2009, 281 pp.

- book review

Poverty and Student Performance in Malaysia

The objectives of this study are to identify the costs of schooling borne by parents, to assess the extent to which these costs place a financial burden on poor and rural parents and to examine the impact of parental income on student performance. The study surveyed both the rural and urban children in Malaysian secondary schools. The evidence underscores the importance of schooling expenditure and the distribution of the availability of schooling facilities to all. Providing sufficient financial assistance such as subsidies and scholarships for poor students should continue to be very high on policy agenda.- schooling expenditure, secondary schools, student performance, Malaysia

Modelling of liquid-liquid dispersions in batch stirred vessels

Imperial Users onl

Multi-Robot Auction Based Coordination

This dissertation studied the coordination problem for a Task Initiator (TI) with multiple ground stations (GSs). Each GS has a team of unmanned aerial vehicles (UAVs) that frequently collected data from a set of unattended ground sensors (UGSs) and delivered it to the source ground station (GS)

Use Of Mushroom Extract To Enhance Quality And Health Benefits Of Dairy Products

The overall goal of this project is to develop a new technique that could be applied in the food industry to ensure food-grade probiotics that extend the viability longer, express α-galactosidase/ β-galactosidase, and overall to enhance the quality of dairy products. Specific objectives to be accomplished are as follows: 1) to investigate the effect of mushroom extract on growth of 3 bifidobacteria and lactobacillus in vitro; 2) to determine the effect of shiitake mushroom extract on the pH, titratable acidity, viability and α-galactosidase/ β-galactosidase of probiotics in milk during refrigerated storage; 3) to study the impact of mushroom extract on viability and α-galactosidase/β-galactosidase activities of probiotics in yogurt products during refrigerated storage

LmeA, a Conserved Cell-Envelope Protein in Mycobacteria, is Important for Antibiotic Resistance and Cell Envelope Permeability

The cell envelope of mycobacteria is critical for the survival and virulence of pathogenic species during infection, and its biosynthesis has been a proven drug target. Therefore, finding new targets in the biosynthetic pathway of cell envelope components is of great interest. Mycobacterium smegmatis is a model organism for the study of the devastating pathogen Mycobacterium tuberculosis. Previously, lipomannan elongation factor A (LmeA) has been identified as a cell envelope protein that is critical for the control of mannan chain length of lipomannan (LM) and lipoarabinomannan (LAM), lipoglycan components of the cell envelope. The deletion mutant, ∆lmeA, accumulates abnormal LM/LAM with fewer mannan residues. To understand the importance of this protein, the antibiotic sensitivity of ∆lmeA was tested using a resazurin-based viability assay. We found that the lmeA deletion leads to increased sensitivities to antibiotics such as vancomycin and erythromycin, and lmeA overexpression leads to increased antibiotic resistance. To directly test if the increased antibiotic sensitivity is due to the defective permeability barrier, we used an ethidium bromide uptake assay and found that ∆lmeA is more efficient in taking up ethidium bromide in the cell. We have also found that LmeA is important for protein stabilization under stress conditions. MptA is an α1,6-mannosyltransferase involved in elongation of LM and LAM mannan chain. During stress conditions in the ΔlmeA mutant, levels of MptA decrease significantly relative to wild-type. This also results in delayed doubling time after stress, a phenotype not seen in this mutant under normal growth conditions. In addition, the ΔlmeA mutant has differential protein expression during stress conditions relative to ΔlmeA in log phase, or to wild-type in either condition. To help elucidate the role of LmeA at the molecular level, binding behavior of this protein to membrane fractions was determined. In a subcellular fractionation analysis, LmeA localizes to fractions containing plasma membrane, which is tightly bound to cell wall layers. To test the binding of LmeA to membrane further, LmeA was heterologously expressed in Escherichia coli, purified, and mixed M. smegmatis cell lysate. LmeA localized to intracellular domain fractions (IMD), indicating that LmeA is capable of localizing to fractions containing only plasma membrane. Consistent with this finding, LmeA is capable of binding to spheroplasts in both an ELISA setting as well as in a sucrose gradient fractionation setting. It has also been determined that ΔlmeA has a defective capsular layer with a unique phenotype relative to other strains. We have concluded that LmeA is important for antibiotic resistance, cell envelope permeability, capsule formation, stress response, and have also determined its binding properties

George W. Bush, September 11th and the rise of the Freedom Agenda in US-Middle East relations: a Constructivist Institutionalist approach

This thesis generates a greater understanding of the George W. Bush administration’s Freedom Agenda for the Middle East and North Africa. It is motivated by two central research questions: How and why was the Freedom Agenda developed? And, how was the Freedom Agenda constituted? To address these questions, a constructivist institutionalist methodology is developed. The value of this undertaking, is that it theorises the relationship between the events of September 11, 2001, and the rise of the Freedom Agenda. Consequently, this research focuses on the narrative constructed in the aftermath of the “crisis”, and how this laid discursive tracks for the evolution of the Freedom Agenda. Furthermore, it is demonstrated that the Bush administration appropriated and articulated multiple discourses into a distinctive ideological-discursive formation, which in turn, sedimented particular definitions of concepts such as ‘democracy’ and ‘freedom’. This created a new policy paradigm, which failed to address the ‘conflict of interests’ problem central to US-Middle East relations. As a result, the Freedom Agenda demonstrated a commitment to regional stability and the gradual reform of ally regimes, whilst seeking to challenge regimes hostile to the US. It was a policy caught between promoting democracy and domination

Effect of Working Capital Management on Firm’ Financial Performance: A Survey of Water Processing Firms in Puntland

The study aimed to establish the effect of working capital management on financial performance of water processing firms in Puntland state of Somalia. The study period of 2011 to 2015 was divided into financial quarters with working capital and financial performance variables determined for each of these quarters. There were four specific objectives for the study relating to the effect of firstly cash management, secondly inventory management, thirdly receivables management and lastly payables management on financial performance of the water processing firms. Three theories used in the study are the agency theory, transactional cost theory and working capital management cycle theory. The study used descriptive survey to accomplish the objectives. The study focused on a convenient sample of four companies located in Garowe. It used multiple linear regression of return on assets (ROA) on the four independent variables of cash conversion cycle ratio (CCR), stock turnover ratio (STR), receivables turnover ratio (RTR) and payables turnover ratio (PTR). The findings from descriptive statistics indicated that all the variables are very volatile given the high values of coefficient of variation for each of the variables. From inferential statistics, the study found out that CCR and STR have a positive effect on return on assets of the water companies in Garowe. Receivables turnover, the indicator of receivables management had however a negative effect of ROA. The last working capital variable, payables turnover ratio had no effect on financial performance of water companies as indicated by ROA. The study concludes that the findings which in some cases are not similar to findings from elsewhere could be because of the unstable nature of the business environment in Puntland state of Somalia and Somalia in general. Because of the study limitations, the study makes two recommendations for further study that is there should be studies to cover a wider population of water companies in Somalia to check the effect of working capital on financial performance will remain the same after adjusting for the increased population. A similar study could be done for other types of companies outside of the water processing firms in Puntland. Keywords: Cash management, Inventory management, Receivables management, Payables management & financial performance.

Somali Higher Education: Current State, Challenges and Opportunities as a Case Study of Somali National University

The main objectives of the study were to find out the challenges and opportunities of higher education in post conflict societies for the time being as a case of Somali National University in Mogadishu, Somalia. A descriptive research design was used and the study population were Bachelor, Master, and PhD holders at Somali National University. A sample size of 25 respondents was taken. Self administered questionnaires were used to collect the data from the respondents and evaluated by utilizing descriptive statistics with the aid of SPSS. The findings discovered that higher education for the time being contributes peace building as well as good governance in post-conflict societies. Keywords: Somali higher education: current state, challenges and opportunities and Somali National Universit