热-力-电耦合下天线罩电性能仿真及分析

在实际飞行工况下,热力载荷会改变高速飞行器天线罩原有的电磁特性,从而影响制导性能。提出了一种基于六面体网格划分的热-力-电耦合模型及仿真方法,可准确表征高速飞行工况下天线罩介电温漂和结构变形对电性能的影响。基于天线罩热-力-电共享网格模型,首先通过瞬态热仿真得到天线罩响应温度场,通过静力分析得到天线罩结构变形场。然后,将天线罩介电温漂和结构变形准确传递到其电磁仿真模型中,并采用三维射线跟踪法计算其电性能。最后通过一个典型算例对高速飞行工况下天线罩电性能的变化进行仿真和分析,结果表明电性能变化非常明显,也进一步说明了所提方法的可行性和研究的必要性。

压力传感器零漂对陶瓷液压自动压砖机的影响

本文介绍了压力传感器零漂对陶瓷液压自动压砖机压制的影响,论述了压力传感器零漂的原因和防护措施。在陶瓷砖成型压制过程中,要求压力传感器能够真实、客观、快速准确地反应主油缸内的压力情况,以提高砖坯生产的优等品率。

SPICE model of trench-gate MOSFET device

A novel simulation program with an integrated circuit emphasis（SPICE） model developed for trench-gate metal-oxide-semiconductor field-effect transistor（M OSFET）devices is proposed. The drift region resistance was modeled according to the physical characteristics and the specific structure of the trench-gate MOSFET device. For the accurate simulation of dynamic characteristics, three important capacitances, gate-to-drain capacitance Cgd, gate-to-source capacitance Cgsand drain-to-source capacitance Cds, were modeled, respectively, in the proposed model. Furthermore,the self-heating effect, temperature effect and breakdown characteristic were taken into account; the self-heating model and breakdown model were built in the proposed model; and the temperature parameters of the model were revised. The proposed model is verified by experimental results, and the errors between measured data and simulation results of the novel model are less than 5%. Therefore, the model can give an accurate description for both the static and dynamic characteristics of the trench-gate MOSFET device.

The study and analysis of floating datum selection for rugged terrain

We analyze the characteristics of different floating datums for static corrections and discuss the methods for determining them. The effect of different floating datum corrections was studied using theoretical model experiments, resulting in the conclusion that the velocity obtained after the floating datum correction with the minimum static correction errors depends on the velocity of the layer below the low velocity layer （LVL） lower boundary and is not related to topographic relief and LVL structure. For the real data processing case, wave equation numerical model experiments were conducted which resulted in a new method for calculating objective functions based on the waveform and modifications to the calculation equation for minimum static correction errors to make the method suitable for real data static correction processing using inhomogeneous velocity models with lower velocity boundary relief. Real data processing results demonstrate the method＇s superiority.

NAND flash service lifetime estimate with recovery effect and retention time relaxation

A service life model of NAND flash and threshold voltage shift process is proposed to calculate the service life and endurance.The relationships among achievable program/erase(P/E) cycles,recovery time,bad block rate and storage time are analyzed.The achievable endurance and service life of a NAND flash are evaluated based on a flash cell degradation and recovery model by varying recovery time,badblock rate,and storage time.It is proposed to improve the service lifetime of solid state disk by both relaxing the bad block rate limitation and retention time while extending the recovery time.The results indicate that endurance can be improved by 17 times if the storage time guarantee is reduced from 10 a to 1 a with 105 s recovery time inserted between cycles.

Process and anodic reaction mechanism of cadmium electrically enhanced cementation on zinc plate under an ultrasonic field in ammoniacal system

Cadmium was replaced by zinc in ammoniacal system using an electrically enhanced method under ultrasonic waves.Five main influencing factors were investigated by a single-factor experiment to determine the optimum parameters.Cyclic voltammetry and linear sweep voltammetry were applied to investigating the reaction mechanism of electrically enhanced cementation of cadmium on a zinc plate.The optimum parameters were a temperature of 35℃,a cathode-to-anode area ratio of 1:2,an anode current density of 15 A/m2,an ultrasonic frequency of 40 kHz a reaction time of 6 h and an ultrasonic power of 100 W.The extraction rate was 99.21%,and the production of byproduct“floating sponge cadmium”was inhibited.The analysis of the cyclic voltammetry and linear sweep voltammetry diagrams showed that ultrasonic waves can promote and accelerate the replacement reaction,decrease the voltage requirement of the electrically enhanced replacement reaction,and change the reaction steps.In addition,increasing the temperature and ultrasonic power can promote and accelerate electrically enhanced replacement reactions and decrease the electric potential requirement.

Effect of wave-induced Stokes drift on the dynamics of ocean mixed layer

The wave-forcing 'Coriolis-Stokes forcing' and 'Stokes-vortex force' induced by Stokes drift affect the upper ocean jointly.To study the effect of the wave-induced Stokes drift on the dynamics of the ocean mixed layer,a new three-dimensional(3D) numerical model is derived using the primitive basic equations and Eulerian wave averaging.The Princeton Ocean Model(POM),a 3D primitive equation ocean model is used with the upper wave-averaged basic equations.The global ocean circulation is simulated using the POM model,and the Stokes drift is evaluated based on the wave data generated by WAVEWATCH III.We compared simulations with and without the Stokes drift.The results show that the magnitude of the Stokes drift is comparable with the Eulerian mean current.Including the Stokes drift in the ocean model affects both the Eulerian current and the Lagranian drift and causes the vertical mixing coefficients to increase.

Correlating Photovoltaic Performance of Dye-Sensitized Solar Cell to the Film Thickness of Titania via Numerical Drift-Diffusion Simulations

The thickness of TiO2 film is vital to realize the optimization on photovoltaic performance of dye sensitized solar cells （DSSCs）. Herein, the process of charge separation in DSSCs was simulated by using a drift-diffusion model. This model allows multiple-trapping diffu- sion of photo-generated electrons, as well as the back reaction with the electron acceptors in electrolyte, to be mimicked in both steady and non-steady states. Numerical results on current-voltage characteristics allow power conversion efficiency to be maximized by varying the thickness of TiO2 film. Charge collection efficiency is shown to decrease with film thick- ness, whereas the flux of electron injection benefits from the film thickening. The output of photocurrent is actually impacted by the two factors. Furthermore, recombination rate constant is found to affect the optimized film thickness remarkably. Thicker TiO2 film is suitable to the DSSCs in which back reaction is suppressed sufficiently. On the contrary, the DSSCs with the redox couple showing fast electron interception require thinner film to alleviate the charge loss via recombination. At open circuit, electron density is found to decrease with film thickness, which engenders not only the reduction of photovoltage but also the increase of electron lifetime.

Theoretical Study on Drift of Ca^(2+)Spiral Waves Controlled by Electric Field

Based on the Tang-Othmer Ca^2＋ model, the drift behavior of intracellular Ca^2＋ spiral waves under the influence of weak electric field is investigated. Numerical results show that the dependence of drift velocity of the spiral tip on dc electric field is similar to experimental observations in BZ system. When an ac electric field is applied, interesting resonant-drift phenomenon is observed with ω=2ω0. All results can be explained analytically using a proximate method.

Development of Electron Temperature Measuring System by Silicon Drift Detector

The soft X-ray spectroscopy, laser Thomson scattering and electron cyclotron emission （ ECE ） are usually adopted for electron temperature measurement in fusion research of magnetic confinement. The particular soft X-ray spectroscopy has the very good spatial-temporal resolution and smaller measuring error than laser Thomson scattering, a close spatial-temporal resolution to ECE, absolute measurement ability, and smaller influence by suprathermal and runaway electrons than ECE.

A New High Voltage SOI Device with a Nonuniform Thickness Drift Region and Its Optimization

A new SO1 high-voltage device structure with nonuniform thickness drift region （n-uni SOl） and its optimiza- tion design method are proposed. Owing to the nonuniform thickness drift region, the electric field in the SOl layer is modulated and the electric field in the buried layer is enhanced, resulting in an enhancement of breakdown voltage. An analytical model taking the modulation effect into account is presented to optimize the device structure. Based on the analytical model, the dependencies of the electric field distribution and breakdown voltage on the device parameters are investigated. Numerical simulations support the analytical model. The breakdown voltage of the n-uni SOl LDMOS with n = 3 is twice as high as that of a conventional SO1 while its on-resistance maintains low.

Time Drift Stabilizer Unit in BEPCⅡ Injection Kicker System

High time-stability performance of the injection kicker system is important for the Beijing Electron Positron Collider Upgrade Project (BEPCⅡ),with jitter and drift less than±5ns.In order to compensate the delay time drift of thyratron on the kicker pulsed power supply,a drift stabilizer is developed.The test results meet the demand of design by regulation resolution=1ns,jitter+drift<2ns in 8 hours.The detailed design of the time-drift stabilizer will be described in this paper.

Modulating the threshold voltage of oxide nanowire field-effect transistors by a Ga^＋ ion beam

In this paper, we report a method to change the threshold voltage of SnO2 and In2O3 nanowire transistors by Ga^＋ ion irradiation. Unlike the results in earlier reports, the threshold voltages of SnO2 and In2O3 nanowire field-effect transistors （FETs） shift in the negative gate voltage direction after Ga^＋ ion irradiation. Smaller threshold voltages, achieved by Ga^＋ ion irradiation, are required for high-performance and low-voltage operation. The threshold voltage shift can be attributed to the degradation of surface defects caused by Ga＋ ion irradiation. After irradiation, the current on/off ratio declines slightly, but is still close to -106. The results indicate that Ga^＋ ion beam irradiation plays a vital role in improving the performance of oxide nanowire FETs.

Effect of temporal variation rate of cross polar cap potential on the equatorial ionospheric vertical drift: A statistical study

Based on the equatorial vertical ion drift measured by DMSP and cross polar cap potential （Фcpc） from AMIE output during 2001 to 2003, this paper investigates the relationship of Фcpc and its temporal variation rate （△Фcpc） with the disturbed ion velocity （△Vx） which is the difference between the disturbed days （Kp〉4） and quiet days （Kp〈2）. The statistical analysis shows： （1） The △Vx correlates better with AФcpc than with Фcpc, indicating that the electric field penetration is more easily to occur when solar wind input rapidly varies with time. （2） The optimal delay time of electric field penetration from the high-latitude magnetosphere to equatorial ionosphere has local time dependence which is longer on the nightside than on the dayside. It may be due to more complicated electrodynamic process on the nightside. （3） With the linear relationship between △Фcpc and △Vx, it is obtained that the penetration efficiency is about 4.5%-13.9% at day and 31%-42% at night, coinciding well with former studies.

Determining wind field and electric field by a barium release experiment in the ionosphere

Barium release experiment is an effective way to study the near-earth environment, in which artificial plasma cloud is created via ionization of neutral gases released from a rocket or a satellite. The first barium release experiment in China was success- fully carried out by a sounding rocket at a height of about 190 km on April 5, 2013. The observed barium cloud images show that the neutral cloud follows a damping motion, whose velocity decreases exponentially and finally tends towards the wind velocity of the background. But for the ion cloud, the motion is controlled mainly by the Lorentz force and a ExB drift happens This work is devoted to calculating the wind and electric field of the background by analyzing the observed images from dif- ferent stations. It turns out that the wind has a magnitude of 51.28 m/s, which is mainly in the northeast direction but also has an appreciable vertical component; the ion cloud has a drift velocity of 71.38 m/s, with a large vertical velocity component be- sides the horizontal components, then the electric field is obtained from the drift velocity as 2.49 mV/m. It is interesting that the wind field shows a better agreement with GITM model than the other empirical or theoretical models, and the GITM model can also give a good prediction for the ion velocity observed by us, which is consistent with the ISR observation at Jicamarca as well.

Characteristics of low altitude ionospheric electric field over Hainan Island,China

A sounding rocket experiment undertaken by the Chinese Meridian Project from a low latitude station on Hainan Island(19.5°N,109.1°E),China,measured the DC electric field during 05:45-05:52 LT on April 5,2013.The data observed using a set of electric field double probes,as part of the rocket's scientific payload,revealed the special profile of how the vectors of the DC electric field vary with altitude between 130 and 190 km.During the experiment,the vertical electric field was downward,and the maximum vertical electric field was nearly 5.1 mV/m near the altitude of 176 km.The zonal electric field was eastward and slightly less than 0.6 mV/m.The plasma drift velocity was estimated from the E×B motion,and the zonal drift velocity was eastward and of the order of 100 m/s.The zonal wind velocity was also estimated using the drift velocity near the maximum density height in the F1-region,and it was found to be nearly 120 m/s.This work constituted the first in situ measurement of the DC electric field conducted within the Fl-region(between 130 and 190 km) in the East Asian Sector.