FEDSM2006-98347 FIXED VALVE PIEZOELECTRIC MICROPUMP FOR MINIATURE THERMAL MANAGEMENT MODULE

ABSTRACT In this paper, we discuss implementation of a micropump with fixed-geometry Tesla-type valves in a closed-loop forced convection thermal management system. The micropump was integrated with a heat sink in a stacked array and fabricated using a photochemical etching process. Two different micropump cavity diameters of 10-mm and 15-mm were fabricated and tested. For each cavity diameter, there were three valve sizes ranging from 140-µm to 340-µm in width. For the best-performing micropump we also evaluated the impact of varying the aspect ratio by adding and removing layers within the micropump. Our results indicated that as the diameter or cavity depth increased the performance of the pump in terms of block load pressure and flow rate degraded. Also, decreasing the valve width for each cavity diameter and height tended to increase the block load pressure and the resulting flow rate. For a pump with 140-µm valve width and an optimal cavity height of 550-µm (11-layers), the maximum flow and pressures obtained for a single pump subassembly were nearly 1.1-mL/min and 0.8-psi. A stack of 4 micropump subassemblies provided more than 5.5 mL/min flow rate and 0.5-psi pressure. The micropump power consumption was less than 50-mW per subassembly, and including the driving electronics power conversion, it consumed less than 0.5-W of power under these conditions. The thermal performance of an integrated liquid cooling module on standard Pentium P4 microprocessor running at up to 40-W was comparable to an off-the-shelf heatsink, but in a package less than 1/10 the size. This unit is currently being considered for blade server applications

A system study on the production of the E-Jeepney of the M.D. Juan Enterprises

The E-jeepney production system of MD Enterprises has been in existence since 2008, initially producing two units of e-jeepneys for its first client. This system study on the Production of E-jeepney of M.D Juan Enterprise covered all its production processes from the shearing process until the trimming process for the one-year period of July 2009 to June 2010. The main problem being addressed after a thorough situation appraisal is that The E-jeepney production of MD Juan Enterprise experienced a total of 31 cases of warranty returns which generated an additional expense of Php 174,334.61 for the company. The cause and effect analysis conducted surfaced the following true causes: that 81.90% of the cost returns are due to workers lack of electrical wiring connection and part installation skills, quality control is not fully implemented, 17.63% of the costs from returns are low quality part such as: the battery connector, cable, cut off switch, and transmission which are all coming from the suppliers and parts are not properly stored in the inventory. Recommended solutions were generated to solve these root causes with their corresponding proposed systems: proper screening and monitoring of workers by having a systematic hiring procedure changing the layout of the inventory storage and managing how the materials are handled proposing a training program for the workers and implementing a standardize quality control and pre-delivery inspection for the production. It was shown through the cost-benefit that the solutions are feasible because of the positive net present value of PHP 313,456.64 with a payback period of 7.08 months. The alternative solutions could be implemented within a span of 10 weeks or 2.5 months

Antimicrobial properties of ethanolic crude extract of mangosteen pericarp (garcinia mangostana) against gram-positive bacteria (staphylococcus aureus and streptococcus pyogenes) and gram-negative bacteria (escherichia coli and salmonella enterica serovar typhi)

This study aimed to determine the antimicrobial properties of mangosteen (Garcinia mangostana L.) ethanolic crude extract against gram positive (Staphylococcus aureus and Streptococcus pyogenes) and gram negative bacteria (Escherichia coli and Salmonella enterica serovar typhi). An analytic-experimental study wherein the research design used was randomized control trial (RCT). This was to assess the antimicrobial effect of Garcinia mangostana on gram-positive (Escherichia coli and Salmonella enterica serovar typhi). The effect of the different concentrations of the mangosteen pericarp crude extract had been determined through measurement of the zone inhibition and determination of the minimum inhibitory concentration. Mangosteen pericarp ethanolic crude extract inhibitory and bactericidal effects on gram positive species with a minimum inhibitory and bactericidal concentration of 1500 microgram/mL, on the other hand, it was not inhibitory or bactericidal against the gram-negative representative species