Quartz resonator assembling with TSV interposer using polymer sealing or metal bonding

This paper presents one wafer level packaging approach of quartz resonator based on through-silicon via (TSV) interposer with metal or polymer bonding sealing of frequency components. The proposed silicon-based package of quartz resonator adopts several three-dimensional (3D) core technologies, such as Cu TSVs, sealing bonding, and wafer thinning. It is different from conventional quartz resonator using ceramic-based package. With evaluation of mechanical structure design and package performances, this quartz resonator with advanced silicon-based package shows great manufacturability and excellent performance to replace traditional metal lid with ceramic-based interposer fabrication approach.     

Fermentative hydrogen production using a real-time fuzzy controller

This work builds a real-time monitoring and control system for bio-hydrogen production fermentation plants using LabVIEW software. The best fermentation environment factors pH and temperature are successfully estimated with stable control ability to create the best hydrogen production environment. The concentrate molasses fermentation waste is as nutrients to hold biomass hydrogen production by dark fermentation in a continuous stirred anaerobic bioreactor, CSABR. In order to verify the applicability of this system, this study compares the proposed anaerobic bioreactor system which's maximum hydrogen production was 3.12 (L/Day) and the system with the fuzzy controller which's hydrogen production rose to 13.44 (L/Day). The result shows that the proposed fuzzy control can not only control feeding pump and heater operations, but also successfully reduce the energy required for hydrogen production, making sure the growth of micro-organisms is in the best environmental conditions for the best growth rate and raise of the maximum hydrogen production.     

Experimental and CFD study on the mass flow-rate characteristic of gas through orifice-type restrictor in aerostatic bearings

This paper describes the experimental and CFD study on the mass flow-rate characteristic through an orifice-type restrictor in aerostatic bearings. In the conventional design of gas-lubricated aerostatic bearings, the mass flow-rate of gas through an orifice-type restrictor is generally derived from a well-known mathematical model, which is originally developed to describe the mass flow-rate property through an ideal nozzle. It is reasonable to doubt if there is any difference between the property of mass flow-rate through an orifice and that through a nozzle. In this paper, therefore, a series of simulations and experiments are carried out and the results show that the mass flow-rate characteristic through an orifice is different from that through a nozzle. Consequently, the conventional model to determine the mass flow-rate through an orifice-type restrictor in aerostatic bearings may have to be updated to the proposed new model for more precise design and modelling of the gas-lubricated aerostatic bearings.     

Heavy metal capture and accumulation in bioretention media

Heavy metal capture and accumulation in bioretention media were investigated through the use of a one-dimensional filtration equation for particulate metals, advection/dispersion/adsorption transport equations for dissolved metals, and sequential extractions. Predicted spatial profiles and partitioning patterns of captured metals were compared to data derived from a bioretention cell in the District of Columbia. Zinc, lead, and copper profiles showed a high surface accumulation, significantly decreasing with the media depth. Surface street particle-enriched areas had the highest heavy metal levels, demonstrating a close relationship between capture of metals and runoff particles. Sequential extractions suggested that most captured metals were of anthropogenic origin. Soluble-exchangeable bound metals from the sequential extraction correlated well with predicted aqueous dissolved metals; the more strongly associated metal fractions correlated with modeled runoff and media particulate metals. A simple risk evaluation indicated thatlead isthe limiting metal in bioretention accumulation. On the basis of information collected in this study, a shallow bioretention cell design is suggested for systems with a focus on metal capture.     

Dynamically optimum lookup-table spacing for power amplifier predistortion linearization

The lookup-table-based digital adaptive predistortion (DAPD-LUT) approaches are low cost and effective for power amplifier (PA) linearization in wireless applications. However, most existing DAPD-LUT schemes are sub-optimum because they adopt uniformly spaced LUTs regardless of the system state information (SSI), i.e., the PA characteristics and the input signal statistics. Other existing DAPD-LUT schemes assume either full or partial knowledge of the SSI to optimize and then to freeze the LUT spacing. Without prior knowledge of the SSI, we propose an SSI-learning low-complexity procedure to optimize the LUT spacing for a DAPD-LUT scheme. The proposed procedure is capable of online adapting the LUT spacing for PAs with various nonlinear characteristics, for input signals with various statistics, and for wireless environments with various time-varying properties.     

Exploration of efficiency underestimation of CCR model: Based on medical sectors with DEA-R model

Data Envelopment Analysis (DEA) is one of the best-known efficiency evaluation methods due to its advantages in selection of weights. Many research papers have extensively discussed the issue of weight restrictions, rather than those implied in the model itself. However, this often leads to a failure to represent the relations of certain weights, as well as underestimation of the efficiency of Decision Making Units (DMUs). When analyzing the medical sectors of Taiwan with the developed models and CCR, it is found that efficiency underestimation by efficient DMUs is more serious than that of inefficient DMUs. In addition, underestimation occurs when weights are concentrated in the same output, however, every output of referenced DMU is the same times of corresponding output of targeted DMU.     

Proton-exchanged wet etching of recessed-structure SAW filter

An improved method for fabricating recessed-structure surface acoustic wave (SAW) filters is reported. The relation between proton-exchanged duration and etched depth are studied, as well as the relation between internal reflection, etched depth, and thickness of the aluminum electrode. Experimental results show that the devices have superior performance, and ideas for further improvement of the fabricated SAW device are discussed.     

Contact and frictional behavior of rough surfaces using molecular dynamics combined with fractal theory

The microcontact behavior of a copper asperity on a diamond plate was carried out using a molecular dynamics (MD) simulation with the parallel algorithms atom decomposition method. The results show that the dynamic frictional force had an oscillated behavior when the flat diamond plane slipped through the copper asperity. The contact load, contact area, dynamic frictional force, and dynamic frictional coefficient increased as the contact interference increased at a constant loading velocity. The dynamic frictional force and dynamic frictional coefficient increased as the sliding velocity increased. Furthermore, the microcontact behavior can be evaluated between a rigid smooth flat plane and a rigid smooth hemisphere to a deformable rough flat plane by combining the deformed behavior of the asperity obtained from MD results and the fractal and statistic parameters.     

Tribological process induced conformational transformation of protein may change the friction of cartilage

In-vitro testing procedures have been successfully developed to investigate the effects of tribological process induced transformation of protein-based lubricant on the friction change of articular cartilages. Serum and albumin solutions were the biological lubricants used in this study. The results indicated that the lubricating ability for cartilages deteriorates after the biological lubricants were articulated between polyethylene and stainless steel materials. In addition, the secondary structure change of the albumin molecule has been characterized after the molecules were articulated by the artificial joint materials. We have provided evidence that the conformational change of protein lubricants leads to the friction increase of articular cartilage.     

Synthesis of high temperature cholesteric copolysiloxanes and their use as stationary phases for high resolution gas chromatography

Summary The synthesis of side-chain liquid crystalline copolysiloxanes containing-cholestery14-(10-undecen-1-yloxy)biphenyl-4'-carboxylate and 4-biphenyl 4-allyloxybenzoate mesogenic side groups is present. Differential scanning calorimetry, optical polarizing microscopy measurements reveal wide temperature range of cholesteric phase for all copolysiloxanes. The cholesteric temperature range depends upon the monomer feeding ratio. The copolysiloxanes containing higher percentage of cholesteryl 4-(10-undecen-1-yloxy)biphenyl-4'-carboxylate side group reveal wider temperature range of cholesteric phase. The synthesized copolysiloxanes were used as stationary phase in gas chromatography capillary columns. They show very unique chiral resolution properties for various kinds of enantiomers, i.e., linalool, menthol and menthone. Received: 25 April 2000/Revised version: 9 June 2000/Accepted: 20 June 2000