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In this paper, the separation of variables method is applied to investigate the effects of solution pH, background salt concentration and AC electric field frequency on time periodic electroosmotic flow in a pH-regulated parallel-plate nanochannel. The surface charge is generated by the protonation and deprotonation of the functional group SiOH. The background salt is KCl. The pH value of the solution is adjusted by HCl and KOH. Analytical and semi-analytical solutions for electric potential and velocity distributions are obtained. The results show that the electric potential caused by the electric double layer depends greatly on the solution pH and background salt concentration. The amplitudes of the velocity and flow rate of the time periodic electroosmotic flow decrease with the background salt concentration and increase with the deviation of the solution pH from the isoelectric point. In a nanochannel having a height less than 100 nm, the electroosmotic velocity amplitude is not affected by the AC electric field frequency because the oscillating Reynolds number is much less than unity.

The double-circle grinding traces has 0% velocity deviation percentage (Vdp =0%), which is the optimum polishing trace. This paper focuses on the invention of cam-linkage grinding devices with double-circle grinding traces. First, based on the modified Yan’s creative design methodology, 1st cam-linkage grinding device is synthesized. Then, according to Osborn’s Checklist Method, 2nd cam-linkage grinding device is synthesized. These two cam-linkage grinding devices can be designed to have optimum polishing traces and 0% velocity deviation percentage (Vdp =0%). This paper provides a new creative design methodology for creating some or all possible design concepts that have the different topological characteristics as existing designs, e.g. with the different degrees of freedom. It can be said to create some or all possible design concepts from nothing (no existing design). The results of this paper can be used as the teaching material of innovative design course.

Aluminum alloy is widely used in aerospace and shipbuilding fields, but it is microstructural and mechanical properties of weld bead are not satisfactory. In this paper, GMAW experiments under the magnetic field were carried out. The effect of magnetic field frequency on GMAW process was analyzed through taking the arc images by high-speed camera, detecting spatter rate, observing metallographic microstructural, testing tensile property and observing fracture SEM appearance. The arc shape and arc movement changed with the variation of external magnetic field frequency, which had a crucial influence on arc temperature gradient and undercooling degree and finally took effect on weld appearance and mechanical properties. The experimental results shown that the arc shape was expanded, arc temperature gradient and undercooling degree decrease, weld bead grain becomes coarse, weld appearance and mechanical properties gets worse below the magnetic field frequency of 60 Hz. The arc shape compressed, arc temperature gradient and undercooling degree increase, weld bead grain becomes refined, weld appearance and mechanical properties gets better over 60 Hz compared with conventional GMAW, the spatter rate reduced by 1.8%, the microstructural grain refined obviously and the tensile strength increased by 31.5 MPa.

In this paper we analytically investigate the electroviscous effect and electrokinetic energy conversion in the time periodic pressure-driven flow of an incompressible viscous Newtonian liquid through a parallel-plate nanochannel with surface charge-dependent slip. Analytical and semi-analytical solutions for electric potential, velocity and streaming electric field are obtained and are utilized to compute electrokinetic energy conversion efficiency. The results show that velocity amplitude and energy conversion efficiency are reduced when the effect of surface charge on slip length is considered. The surface charge effect increases with zeta potential and ionic concentration. In addition, the energy conversion efficiency is large when the ratio of channel half-height to the electric double layer thickness is small. The boundary slip results in a large increase in energy conversion. Higher values of the frequency of pressure pulsation lead to higher values of the energy conversion efficiency. We also obtain the energy conversion efficiency in constant pressure-driven flow and find that the energy conversion efficiency in periodical pressure-driven flow becomes larger than that in constant pressure-driven flow when the frequency is large enough.

This paper presents a numerical analysis of the flow and heat transfer characteristics of mixed convection in a micropolar fluid flowing along a vertical flat plate with conduction effects. The governing non-linear equations and their associated boundary conditions are first cast into dimensionless forms by a local non-similar transformation. The resulting equations are then solved using the cubic spline collocation method and the finite difference scheme. This study examines the effects of the buoyancy parameter, the conjugate heat transfer parameter, the micropolar parameter and the Prandtl number on the flow and the thermal fields. The results show that the conjugate heat transfer parameter has a significant influence on the fluid flow and heat transfer characteristics. The buoyancy parameter reduces the solid–liquid interfacial temperature but increases the skin friction factor and the local heat transfer rate. The effect of wall conduction on the local heat transfer rate, interfacial temperature and skin friction factor is found to be more pronounced in a system with a greater buoyancy effect. Finally, compared with the case of pure forced convection, a reduction in the interfacial temperature, an increase in the skin friction factor and an increase in the local heat transfer rate are obtained in the current mixed convection case.

This paper employs linear and nonlinear stability theories to conduct a numerical characterization of thin micropolar film flows travelling down a vertical moving plate. Having applied the long-wave perturbation method to derive the generalized kinematic equations for a free film surface condition, the multiple scales method is used to solve the micropolar film flow in the cases of a stationary vertical plate, a vertical plate moving in the downward direction and a vertical plate moving in the upward direction. The numerical results indicate that both subcritical instability and supercritical stability conditions may occur in the micropolar film flow system. No obvious change in the supercritical stability condition is observed when the plate moves vertically in the upward or downward direction. The numerical results indicate that a downward motion of the vertical plate tends to enhance the stability of the film flow.

Superjunction devices are reported to provide better high-voltage operation characteristics than conventional abrupt junction devices in silicon power applications. In this study, the superjunction reduced surface field (SJ-RESURF) lateral double diffused metal oxide semiconductor field effect transistor (LDMOSFET) is fabricated on a bulk silicon wafer to improve the operating characteristics of high-voltage devices. By introducing the p-type strips in the drift region, higher doping concentration of the drift region can be adopted to reduce the conduction resistance. The SJ-RESURF LDMOSFET with a specific on-resistance of 3.53 Ωmm2, a breakdown voltage of 335 V and a drift length of 30 µm, is demonstrated; its turn on-resistance is 25% better than that of the conventional structure. The turn-on resistance, breakdown behavior, device geometry, temperature, and charge balance mechanics of the SJ-RESURF LDMOSFET are examined herein.

Power devices with a high switching speed and a low conduction resistance are crucially important in power conversion circuits. In this study, a trench-gate power metal–oxide–semiconductor field effect transistor (MOSFET) with a high-density cell design 20.6 Mcell/cm2 was implemented for the first time using multilayer dielectrics with an oxide–nitride–oxide (ONO) structure at the bottom of the trench. The thick ONO dielectric layers at the bottom of the trench compensate for the increase in Miller capacitance per unit area as the cell density increases. The resulting device exhibits excellent characteristics of gate charge, switching power loss, gate oxide quality and practical process stability, superior to those of the conventional structure. An n-channel 25.8 V trench gate MOSFET with a specific on-resistance of 0.15 mΩm2, and RON×QGD figure-of-merit 41 mΩnC is presented.

As a new passive sensor, fiber Bragg grating (FBG) sensors have provided a new idea for the SRM shell damage detection, which is to integrate the FBG sensor network in the material interior or to the surface to monitor the shell structure. However, it is difficult to embed the FBG sensor in filament wound composite material structure for the reason of large tension and high temperature in process of manufacture. Therefore we propose a new method that embed FBG sensor network between the composite shell surface and the thermal protective coating. The calibration of sensor is presented by tensile test and the strain transfer coefficient is gotten. It is certified by the hydrostatic test that the FBG sensors could precisely describe the strain variation and distribution of the composite shell and effectively improve the survival rate by embedding the FBG sensors between the composite shell surface and the thermal protective coating.

A high performance 3 inch 0.5 μ m InP DHBT technology with three interconnecting layers has been developed. The epitaxial layer structure and geometry parameters of the device were carefully studied to get the required performances. The 0.5×5 μ m 2 InP DHBTs demonstrated f t =350 GHz, f max =532 GHz and BV CEO =4.8 V, which were modeled using Agilent-HBT large signal model. As a benchmark circuit, a dynamic frequency divider operating from 110 to 220 GHz has been designed, fabricated and measured with this technology. The ultra-high-speed 0.5 μ m InP DHBT technology offers a combination of ultra-high-speed and high breakdown voltage, which makes it an ideal candidate for next generation 100 GHz+ mixed signal integrated circuits.

A common base four-finger InGaAs/InP double heterojunction bipolar transistor with 535 GHz fmax by using the 0.5 μm emitter technology is fabricated. Multi-finger design is used to increase the input current. Common base configuration is compared with common emitter configuration, and shows a smaller K factor at high frequency span, indicating a larger breakpoint frequency of maximum stable gain/maximum available gain (MSG/MAG) and thus a higher gain near the cut-off frequency, which is useful in THz amplifier design.

In this paper a perturbation method is introduced to study the electromagnetohydrodynamic (EMHD) flow in a microparallel channel with slightly corrugated walls. The corrugations of the two walls are periodic sinusoidal waves of small amplitude either in phase or half-period out of phase, and the perturbation solutions of velocity and volume flow rate are obtained. Using numerical computation the effects of the corrugations on the flow are graphically analysed. The results show that the influence of corrugation on the flow decreases with Hartmann number. The phase difference of wall corrugations becomes unimportant when the wavenumber is greater than 3 or when the Hartmann number is greater than 4. With the increase in wavenumber, the decreasing effects of corrugations on the flow increase. When the wavenumber is smaller than the threshold wavenumber (it is a function of Hartmann number) and the wall corrugations are half-period out of phase, the corrugations can enhance the mean velocity of EMHD flow. However, the mean velocity is always decreased when the corrugations are in phase.

We report on the development of a PDMS-SMA composite whose surface micro wrinkles can be dynamically programmed by an electrical current supplied to the SMA wire. It is advantageous over other techniques for surface topographical modulation, including portability, real-time programmability, no requirement for specific surface chemistry, operability under ambient conditions, and relative ease of control. A simplified mechanical model is also developed to describe the force-deflection balance of the PDMS-SMA composite. The wavelengths and amplitudes of the wrinkles when different currents applied to the SMA are characterized, and the experimental results agree with the theoretical model. The developed composite device can be applied to programmable modulations of surface adhesion, friction, wettability, etc.

A bit patterned magnetic array based on Co/Pd magnetic multilayers with a binary perpendicular magnetic anisotropy distribution was fabricated. The binary anisotropy distribution was attained through angled helium ion irradiation of a bit edge using hydrogen silsesquioxane (HSQ) resist as an ion stopping layer to protect the rest of the bit. The viability of this technique was explored numerically and evaluated through magnetic measurements of the prepared bit patterned magnetic array. The resulting graded bit patterned magnetic array showed a 35% reduction in coercivity and a 9% narrowing of the standard deviation of the switching field.

Low-temperature polycrystalline silicon (poly-Si) thin-film transistor lateral double-diffusion metal–oxide–semiconductor field-effect transistors (LTPS TFT LDMOSFETs) and lateral insulated-gate bipolar transistors (LIGBTs) were fabricated by combining a thin-film transistor with a power structure, three-step drift doping, and excimer laser annealing. The maximum breakdown voltage of the three-step drift-doped LTPS-LDMOS after excimer laser annealing is 286 V with a 35 µm drift region length (Ldrift). The specific on-resistance is low (approximately 9 Ω cm2) and the ON/OFF current ratio is about 1.28 ×106 with Ldrift = 15 µm. The subthreshold swing (SS) is about 1 V/decade. Comparing the three-step drift-doped LDMOS with the three-step drift-doped LIGBT under the same processing conditions clearly indicates that the breakdown voltage and current capacity of LIGBT exceeds those of LDMOS.

We demonstrate for the first time that, by using a visible femtosecond laser, it is effective to inactivate viruses such as bacteriophage M13 through impulsive stimulated Raman scattering. By using a very low power visible femtosecond laser having a wavelength of 425 nm and a pulse width of 100 fs, we show that M13 phages were inactivated when the laser power density was greater than or equal to 50 MW cm−2. The inactivation of M13 phages was determined by plaque counts and depended on the pulse width as well as power density of the excitation laser.

In this study, traditional bipolar-complementary metal oxide semiconductor (CMOS)-double diffused metal oxide semiconductor (DMOS) (BCD) technology, which is designed for only lateral bipolar (Bipolar, 12 V BVCEO and 25 V BVCBO), complementary metal oxide semiconductor (CMOS, 1.2 V threshold voltage) and double diffused metal oxide semiconductor (DMOS, 40 V breakdown voltage) transistors on the bulk silicon wafer, has been successfully utilized directly in silicon on insulator lateral double diffused metal oxide semiconductor (SOI LDMOS) for the first time without changing any trial parameters. To simultaneously display the characteristics of high-power, high-speed and high-frequency, the results of output characteristics, switch and microwave performance must be moderate instead of optimum. In addition, according to the experimental results, it is proved that Bulk-BCD technology simultaneously enables high-speed, high-frequency and high-blocking-voltage applications–such as those in high-voltage integrated circuit switches (ns-range) and RF power amplifiers (MHz range to GHz range)–using a SOI wafer.