Transient behavior of subthreshold characteristics of fullydepleted SOI MOSFETs

It has been found that the subthreshold currents of fully depleted silicon-on-insulator (SOI) MOSFETs show a transient behavior under certain front-gate and back-gate voltage conditions. The cause of this anomaly is explained, and applications for the phenomenon are pointed out. Particularly, a simple way to measure the silicon film thickness is suggested     

Design of a product quality control system based on the use of data mining techniques

In recent years industries have increasingly used customer relationship labor in management as a tool to improve their position in the marketplace. This research involves using a data warehouse, decision-tree-based data mining, and neural network pattern classification analysis to isolate the causes of non-conformity in IC packaging. The correctness of the classification analysis produced using the two methods is compared. Our objective is to establish an information analysis system, that is able to quickly identify the causes of problems thereby reducing the time taken to solve quality-related problems. It is shown that predictions made about the target group using decision tree analysis are more accurate than those made by neural network classification, indicating that decision tree analysis is an effective means of classification analysis of a company's quality problems.     

CW high power single-lobed far-field operation of long-cavityAlGaAs-GaAs single-quantum-well laser diodes grown by MOCVD

Data on long-cavity 100-μm-wide broad-stripe laser diodes that lase with a barrow single-lobed far-field pattern in continuous room-temperature operation are presented. Diodes with a cavity length of 1250 μm emit a power of 200 mW per facet into a 2.5° lobe (full width at half maximum). Short-cavity devices (cavity length of 350 μm) lase with a continuously increasing number of lateral modes right from threshold, and exhibit a far-field divergence that is over three times greater than that of 1250-μm diodes. Explanations for the effect of increasing cavity length on the field patterns of these devices are proposed, based on the measured increase in injected carrier diffusion length in long-cavity diodes and the influence of thermal waveguiding and mirror losses on intermodel discrimination     

Probing acid sites in MAPO-36 by solid state NMR

An ordering of magnesium is observed in the as-synthesized MAPO-36 molecular sieve. Upon calcination, part of the magnesium is removed from the sample and part occupies extraframework positions thus rendering a random distribution of magnesium in the lattice. The shoulder observed in the³¹P spectrum of the calcined sample is assigned to P(3Al, 1Mg) sites in conflict with the earlier assignment to P-OH groups. The bridging hydroxyl groups located at these sites are detected in the¹H MAS spectrum at 3.6 ppm. Further, MAPO-36 catalyzed acetone conversion to mesityloxide that cracked at elevated temperature to yield acetic acid and aliphatics.     

The effect of dietary polyunsaturated fatty acids (PUFA) on acute rejection and cardiac allograft blood flow in rats

For six weeks, recipient (Lewis RT11) and donor rats (LBNF11/n) were fed three diets that varied only in their lipid content. Diet A (MO) contained 19.5% menhaden oil and 0.5% safflower oil and was rich in omega 3 PUFA; diet B (SO) was 20% safflower oil rich in omega 6 PUFA; and diet C (BT) was 20% beef tallow rich in omega 9 monounsaturated fatty acids and saturated fat. In the first set of graft survival studies a group fed laboratory chow was included (CHOW). Heterotopic cardiac transplantation from donor to recipient animals was performed after the six-week feeding period. The effect of these diets on cardiac allograft survival, mixed lymphocyte response, and blood flow in the rejecting grafts was investigated. The median graft survival in days was significantly prolonged in the rats maintained on either MO (12 days) or SO (14.5 days) compared with the BT (8 days)-or lab chow (7.5 days)-fed animals (P < 0.05). Cyclosporine (CsA) administered at subtherapeutic levels further increased the differences between the PUFA-fed animals and the BT-fed group. The myocardial blood flow of the rejecting allografts was measured using an 85Sr-labeled microsphere technique on the fifth posttransplant day. Flow was greatest in the MO-fed group, and both MO and SO groups had significantly higher myocardial blood flow than BT-fed rats (P < 0.05) or those bearing isografts. The allogenic mixed lymphocyte responses of peripheral blood mononuclear cells (PBMC) and splenic lymphocytes were suppressed in MO- and SO-fed groups compared with BT-fed animals. The immunosuppressive effect of dietary PUFA warrants further investigation, and their use as a possible adjunctive treatment in organ transplantation should be considered.     

The modeling and implementation of tri-rotor flying robot

The objective of this study is to develop a tri-rotor flying robot, which adopts the Y-shaped three-rotor structure. In order to balance the yaw torque produced by the three rotors, the RC servomotor and linkage is installed on the tail axis in order to improve the angle of the rolling axis of the tail motor. Moreover, through the torque generated by the horizontal component of the lift from the inclined motor on the tail axis, it balances the yaw torque of the three rotors. The dynamic equations of the tri-rotor flying robot are determined in this paper. The relationship between motor thrust, angular acceleration, and voltage input was also studied in this research. In order to study the effect of control parameters on the flight stability completely, this study develops a universal stability experimental platform to help tuning the control parameters safely. Based on this, the tri-rotor flying robot can rapidly change flying gesture and avoid oscillation. Finally, we conducted some indoor and outdoor flight tests. From the experimental results, the tri-rotor flying robot can fly and hover stably in the sky.     

Properties of modified polyacrylonitrile membranes prepared by copolymerization with hydrophilic monomers for water–ethanol mixture separation

A new kind of terpolymer membrane was employed to separate a permselective water–alcohol mixture. This membrane was prepared via the copolymerization of acrylonitrile, sodium salt styrene sulfonic acid (SStSA), and hydroxyethyl methacrylate in dimethylsulfoxide with azobisisobutyronitrile as an initiator. The reaction mechanism, resultant structure, and polymer composition were confirmed by IR and elemental analysis. The effects of the feed composition on the polymer composition, mechanical properties, thermal properties, and degree of swelling were investigated. It was found that water permeated through the membrane preferentially in a water/alcohol system. The flux increased with the increase of SStSA, but the separation factor decreased drastically with higher SStSA. For a 50 wt % water–ethanol mixture, a flux of 0.65 kg/m² h and a separation factor of 212 were obtained at 30°C when the membrane containing the highest SStSA content was used. The capacities of the metal ions absorbed by the membranes were investigated in the study. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 244–250, 2003     

New method for determination of the pose of the grinding wheel for thinning drill points

Traditionally, twist drills are reconditioned by thinning the web so the correct chisel edge length is restored. Recently, thinning has been included in the original design of drills so as to reduce torque and tool force. Because the International Standards Organization (ISO) has a system which can comprehensively model conventional twist drills but cannot model thinning specifications, this paper presents a system for precise mathematical modeling and CNC control of a 6-axis grinding workstation for drill thinning. The presented method determines the position and orientation of the grinding wheel based on the evaluated rake and clearance angles of ISO standards for 2-flute twist drills. The mathematical model and background are discussed. For verification and demonstration, two experimental drills are produced to the identical ISO standard except that one is thinned. The modeling herein is of value to industry and research if incorporated into computer software for drill design and manufacture. It is suitable for linear notch-type cutting with controlled variable rake angle along the secondary cutting edge for purposes of thinning, notching, dubbing and advanced drill research.     

Interaction of calcium channel antagonists with calcium: spectroscopic and modeling studies on diltiazem and its Ca2+ complex

Using spectral techniques, the solution conformation of diltiazem was studied in acetonitrile with special reference to the effect of Ca2+ on the drug structure. Complete assignment of the proton resonances in the 1H-NMR spectrum of the drug was made using one-and two-dimensional spectral analyses. A two-dimensional 1H-NOESY spectrum (in the phase-sensitive mode) was obtained to identify the interproton connectivities in the drug molecule. A molecular modeling program involving Monte Carlo simulation and energy minimization was employed to arrive at the structure of the drug. The program was run with and without the input of the interproton distances derived from the NOESY cross peaks. Both the protocols led to a structure of the drug which was generally similar to that reported from X-ray diffraction data on crystalline diltiazem hydrochloride (Kojic-Prodic, et al. Helv. Chim. Acta 1984, 67, 916-926). However, significant differences between the two structures were seen in the orientations of the substituent groups attached to the benzothiazepine ring. Substantial changes in the circular dichroic (CD) and 1H-NMR spectra of diltiazem were observed on addition of Ca2+ up to a mole ratio of 0.5 Ca2+ per drug. Relatively large changes were seen in 1H resonances of the N-methyl protons and the methylene protons attached to the heterocyclic nitrogen. Analysis of the binding isotherms from CD data at 22 +/- 1 degrees C indicated a 2:1 drug:Ca2+ "sandwich" complex with an estimated dissociation constant of 140 microM. One-dimensional difference NOE and two-dimensional NOESY spectra revealed interproton connectivities between two drug molecules that were compatible with the sandwich complex formation. The interproton distances derived from the volume integrals of the NOESY cross peaks were used as geometrical constraints in modeling the Ca(2+)-bound conformation of diltiazem. The minimum-energy conformation corresponded to the sandwich complex where Ca2+ was coordinated to three oxygens in each of the two drug molecules. Combined with our earlier data on the ability of diltiazem to translocate Ca2+ across the lipid bilayer in synthetic liposomes (Ananthanarayanan, V.S.; Taylor, L.; Pirritano, S.Biochem. Cell Biol. 1992, 70, 608-612), the structural data presented here point to a role for Ca2+ in the interaction of diltiazem with its membrane-bound receptor.     

Design and analysis of power‐CMOS‐gate‐based switched‐capacitor DC–DC converter with step‐down and step‐up modes

A unified multi‐stage power‐CMOS‐transmission‐gate‐based quasi‐switched‐capacitor (QSC) DC–DC converter is proposed to integrate both step‐down and step‐up modes all in one circuit configuration for low‐power applications. In this paper, by using power‐CMOS‐transmission‐gate as a bi‐directional switch, the various topologies for step‐down and step‐up modes can be integrated in the same circuit configuration, and the configuration does not require any inductive elements, so the IC fabrication is promising for realization. In addition, both large‐signal state‐space equation and small‐signal transfer function are derived by state‐space averaging technique, and expressed all in one unified formulation for both modes. Based on the unified model, it is all presented for control design and theoretical analysis, including steady‐state output and power, power efficiency, maximum voltage conversion ratio, maximum power efficiency, maximum output power, output voltage ripple percentage, capacitance selection, closed‐loop control and stability, etc. Finally, a multi‐stage QSC DC–DC converter with step‐down and step‐up modes is made in circuit layout by PSPICE tool, and some topics are discussed, including (1) voltage conversion, output ripple percentage, and power efficiency, (2) output robustness against source noises and (3) regulation capability of converter with loading variation. The simulated results are illustrated to show the efficacy of the unified configuration proposed. Copyright © 2003 John Wiley & Sons, Ltd.