Heat Transfer And Deformation Of Flexible Printed Circuit Board With Multi Ball Grid Array Packages

The rapid development of electronic and microelectronic technology increases the demands for electronics device with flexible and light weight capability. Flexible printed circuit board (FPCB) which can be used to replace rigid printed circuit board (RPCB) is well equipped with those features. However, the soft feature of FPCB poses unwanted deflection (δ) and stress from the flow and heat generated by the operating components. In present research, thermal and flow effects on FPCB with attached ball grid array (BGA) packages have been investigated where the numerical simulation with coupled of flow and thermal effects concurrently has been successfully developed in the simulation. The effects of flow are studied at the initial stage of the research, followed by the addition of heat source to the BGA packages. The experimental work with actual attached ball grid array (BGA) packages was carried out to verify and validate the results. Findings show that better heat transfer performance on FPCB with an average 24 % higher than RPCB. Several parametric factors are explored including flow velocities (v) (1 – 5 m/s), 1 - 4 number of BGA packages attached, power supplied to the BGA packages (0 – 0.213 W), size of FPCB (80mm2 – 140mm2) and distance between BGA packages (15 mm – 45 mm). The heat transfer coefficient (h) has been added into the responses to study the heat transfer in the cases that involved heat source. Later on, v, δ and h had been normalized into dimensionless Reynolds number (Re), δ/length of FPCB (L) and Nusselt number

Numerical simulation analysis on water jet pressure distribution at various nozzle aperture

The low velocity water jet is required by small scale Unmanned Underwater Vehicle (UUV) to control its position, either to remain statics in its position or to perform a slow and steady locomotion. However, the water jet performance is influenced by the size of nozzle aperture. By studying the pressure distribution around the nozzle area, the water jet velocity could be determined and characterized. In this studies, the ejection pressure was fixed at 23.37 Pa according to the constant actuation. Studies were conducted using ANSYS Fluent software. The results show that the water jet velocity and dynamic pressure are higher for larger nozzle aperture size at constant pressure. The total pressure and dynamic pressure had the lowest pressure drop at certain nozzle aperture size but became constant when the nozzle size was wider. This finding is useful in designing the UUV that powered by contractile water jet thruster

Gelsolin induces colorectal tumor cell invasion via modulation of the urokinase-type plasminogen activator cascade

Gelsolin is a cytoskeletal protein which participates in actin filament dynamics and promotes cell motility and plasticity. Although initially regarded as a tumor suppressor, gelsolin expression in certain tumors correlates with poor prognosis and therapy-resistance. In vitro, gelsolin has anti-apoptotic and pro-migratory functions and is critical for invasion of some types of tumor cells. We found that gelsolin was highly expressed at tumor borders infiltrating into adjacent liver tissues, as examined by immunohistochemistry. Although gelsolin contributes to lamellipodia formation in migrating cells, the mechanisms by which it induces tumor invasion are unclear. Gelsolin’s influence on the invasive activity of colorectal cancer cells was investigated using overexpression and small interfering RNA knockdown. We show that gelsolin is required for invasion of colorectal cancer cells through matrigel. Microarray analysis and quantitative PCR indicate that gelsolin overexpression induces the upregulation of invasion-promoting genes in colorectal cancer cells, including the matrix-degrading urokinase-type plasminogen activator (uPA). Conversely, gelsolin knockdown reduces uPA levels, as well as uPA secretion. The enhanced invasiveness of gelsolin-overexpressing cells was attenuated by treatment with function-blocking antibodies to either uPA or its receptor uPAR, indicating that uPA/uPAR activity is crucial for gelsolin-dependent invasion. In summary, our data reveals novel functions of gelsolin in colorectal tumor cell invasion through its modulation of the uPA/uPAR cascade, with potentially important roles in colorectal tumor dissemination to metastatic sites

Design of floating water wheel for power generation

Floating water wheel could harvest energy from shallow flowing river to increase the potential of hydropower. Various types of water wheels have been studied by other researchers. However, the details of the design such as ridge/blade profile, number of ridges and submerged depth of floating water wheel have not been clearly established. In this research, experiments were carried out in an aquarium to study the optimum number of ridges, submerged depth and four different ridge profiles for a laboratory-scale floating water wheel. The results showed different ridge profiles and pitches and submerged depths contribute significant effects to the rotation of floating water wheel. The result of the experiment was used as reference for prototype design and fabrication. The prototype was tested in a river and successfully produced voltage from the flowing river. The experiment shows that the optimum number of ridges is 13, the best profile is thin flat ridge and maintaining the floating water wheel at certain submerged depth is important to its performance. The prototype concept is suitable for low head flow and varying water level. It is also portable, easily assembled and maintained and able to convert the kinetic energy of the water current into electrical energy

Localized anneal

US8268733Granted Paten

Initial design of automated latex cup robot collector on rough terrain

Despite the growing demand in rubber products, the world rubber production has declined in recent years. In this paper, a prototype of an automated latex cups collecting robot is constructed to assist the workers in the latex collection process. This robot is constructed on a mobile platform with a rear-wheel drive, double wishbone suspension, Ackermann’s steer transmission, motor-driven Four Degree of Freedom (DoF) manipulator arm and a latex storage tank. Ultrasonic sensors and camera are employed to locate the position of rubber trees and latex cups. The developed prototype robot has undergone the functional test to verify the control system, in which the robot can collecting the latex cup located at the height of 105 cm and 160 cm. In the mobility test, the robot can overcome obstacles of 15 mm height. While in the static test, the platform and the robotic arm can withstand the stress in the range of 107 N/m2. In the balance test, the topple angle is more than 40°, guaranteeing the stability of the robot platform. Those results showed that the prototype design is feasible to perform basic tasks automatically in the unstructured terrain of rubber plantation

A Novel Lattice Structure for Enhanced Crush Energy Absorption

Lightweight and stiff lattice structures are good energy absorbers. This study evaluates the energy absorption capacity of a few common lattice structures printed out of PLA using fused deposition modeling and proposes an improved lattice structure. Simple cubic (SC), honeycomb (HC), body-centered cubic (BCC), and novel PeckGy80 (PG80) lattice structures were subjected to compressive tests. The quasi-static load-displacement behavior of lattice specimens was characterized in terms of specific energy absorption and crush load efficiency. The damage mechanisms were then related to energy absorption. Cracks and brittle fractures occurred in all lattice structures during the crush test. Different lattice structures induced different damage mechanisms, significantly affecting their energy absorption. SC lattice structure showed structural separation at a small displacement, rendering it an ineffective energy absorber. BCC and HC lattice structures demonstrated almost identical shear band failure modes. The PG80 lattice structure, although made of brittle PLA, displayed progressive failure from the bottom layer to the upper layers, exhibiting both a high peak load and stable post-yield behaviour. This damage mode enabled the PG80 lattice to be far superior in terms of specific energy absorption to HC, SC, and BCC lattice structures

The microbial composition and functional roles of different kombucha products in Singapore

10.1080/19476337.2023.2190794CyTA - Journal of Food211269-27

Gelsolin immunohistochemistry in human colorectal carcinoma tissues.

<p>Gelsolin is heterogeneously expressed in a number of primary tumors (A) and liver metastases (B), with islands of low (<i>arrowed in blue</i>) and high (<i>arrowed in red</i>) expression observed within a tumor. Gelsolin expression is mainly cytoplasmic but occasionally, nuclear (C) and perinuclear (D) staining are detected (<i>arrowed</i>). Gelsolin is strongly expressed in a mucinous adenocarcinoma (E) and in stroma (A, B).</p