Stretches of Fluid Materials for Stokes Flow in Circular Cavity

Stretching for fluid materials slowly flowing within a circular cavity is investigated in the present study. Two belts, which are performed in periodic rotations on the boundary, are used to drive the flow motions. It is shown that the stretching values of fluid filaments are very sensitive to the boundary conditions for which different periods and different angle-phase-shifts are used. Flows generated by the rotations with longer periods and∕or flows generated by the two belts rotating out-phase will create greater stretchings, and possibly better stirrings. Furthermore, under these situations the stretching values associated to fluid filaments are much uniformly distributed.     

Intelligent tuning of commutation for maximum torque capability of a switched reluctance motor

Since the winding current and inductance profiles of a switched reluctance motor (SRM) are far from ideal, its torque generating characteristics are quite ambiguous and difficult to optimize quantitatively. In this paper, the intelligent commutation tuning control to improve the torque generating performance of an SRM is presented. First, the effect of the commutation instant on the torque characteristics of a singly excited SRM is observed. Then accordingly, an intelligent method of commutation tuning is developed to improve the torque generating capability. In making the tuning, the minimization of the motor drawn line current is employed as a performance index to equivalently yield maximum torque per ampere (TPA). Finally, the circuit implementation of the developed tuning scheme is carried out. The appropriate commutation makes the motor draw minimum current under any load condition. It follows that the motor conversion efficiency is also improved. In addition, owing to the increased torque generating capability, the tracking and regulation speed control performances are also improved. Some experimental results are provided to demonstrate the effectiveness of the proposed control scheme.     

Profile-assisted instruction scheduling

Instruction schedulers for superscalar and VLIW processors must expose sufficient instruction-level parallelism to the hardware in order to achieve high performance. Traditional compiler instruction scheduling techniques typically take into account the constraints imposed by all execution scenarios in the program. However, there are additional opportunities to increase instruction-level parallelism for the frequent execution scenarios at the expense of the less freuent ones. Profile information identifies these important execution scenarios in a program. In this paper, two major categories of profile information are studied: control-flow and memory-dependence. Profile-assisted code scheduling techniques have been incorporated into the IMPACT-I compiler. These techniques are acyclic global scheduling and software pipelining. This paper describes the scheduling algorithms, highlights the modifications required to use profile information, and explains the hardware and compiler support for dealing with hazards that arise from aggressive use of profile information. The effectiveness of these profile-based scheduling techniques is evaluated for a range of superscalar and VLIW processors.     

Improvement of hot-carrier and radiation hardnesses inmetal-oxide-nitride-oxide semiconductor devices byirradiation-then-anneal treatments

The hardnesses of hot-carrier and radiation of metal-oxide nitride-oxide semiconductor (MONOS) devices can be improved by the irradiation-then-anneal (ITA) treatments. Each treatment includes an irradiation of Co-60 with a total dose of 1M rads(SiO₂) and an anneal in N₂ at 400°C for 10 min successively. This improvement can be explained by the release of SiO₂/Si interfacial strain     

Aerosol-induced lung injuries observed by synchrotron radiation X-ray phase-contrast imaging technique

Adverse health effects are associated with the inhalation of a variety of atmospheric particles. To study the lung injuries caused by aerosol PM_2.5, synchrotron radiation (SR) X-ray phase-contrast imaging technique was used. Nude mice were inoculated with PM_2.5 samples collected from suburban area (JD), industrial area (BS) and traffic tunnel (DPQ) of Shanghai. From X-ray phase-contrast images of lung tissues, apart from blood vessels and structures of alveoli, even hemorrhage spots of several microns caused by the inflammation were clearly observed. The studies showed that the PM_2.5 samples collected from the traffic tunnel (DPQ) produced higher level of lung injury, followed by the aerosol samples collected from industrial area (BS) and suburban area (JD). Our studies also helped us to understand the process of lung injuries caused by aerosol particles.     

A systematic study of the initial electrical and radiation hardnessproperties of reoxidized nitrided oxides by rapid thermalprocessing

The initial electrical and radiation hardness properties of MOS capacitors with reoxidized nitrided oxides (RNO) structures are systematically investigated by changing the pressure, temperature, and times of nitridation and reoxidation in rapid thermal processes. It was found that the initial flat-band voltage (V_fb) and midgap interface trap density (D_itm) are strongly dependent on the growth conditions and show concave or convex “turnaround” dependency on some process parameters. This may be explained by the hydrogen evaporation and oxygen passivation mechanisms. The radiation induced flat-band voltage shift (ΔV_fb) and midgap interface trap density shift (ΔD_itm) are also growth-condition dependent and show different “turnaround” dependencies on some process parameters from those observed in initial properties. This may be explained by the variations of the amount of hydrogen-related species such as Si-NH, Si-H, or Si-OH, and nitrogen-related species, such as Si-N, in the oxide bulk and at the Si/SiO₂ interface. Finally, the sample with a reoxidation pressure of 250 torr, a reoxidation temperature of 1050°C, and a reoxidation time of 100 s is suggested to be the most radiation-hard together with good initial properties for RNO devices     

17.3% efficiency metal-oxide-semiconductor (MOS) solar cells withliquid-phase-deposited silicon dioxide

Simple and high efficiency silicon metal-oxide semiconductor (MOS) solar cells, with silicon dioxide prepared by a room-temperature liquid phase deposition (LPD) method, are proposed. The thickness of LPD oxide is about 5 nm. After adding a 2~5 nm semi-transparent thin Al film between the 200 nm patterned Al cathode, all the solar cells' performance parameters are improved. For a cell exposed under 15 mW/cm ², short-circuit current density J_SC up to 10.7 mA/cm², open-circuit voltage V_OC up to 412 mV, fill factor FF up to 59, and record effective conversion efficiency η up to 17.3% are obtained for this structure. Photo-conductivity properties of LPD oxide are found and the mechanism is discussed