Almost Periodic Solutions of One Dimensional Schrödinger Equation with the External Parameters

A whitney family of almost periodic solutions for one dimensional Schrödinger equations with the external parameters are proved. It’s based on a detailed analysis to the shift of frequency and an improved infinite dimension KAM theory.     

Incident particle range dependence of radiation damage in a power bipolar junction transistor

The characteristic degradations in silicon NPN bipolar junction transistors(BJTs) of type 3DD155 are examined under the irradiations of 25-MeV carbon(C),40-MeV silicon(Si),and 40-MeV chlorine(Cl) ions respectively.Different electrical parameters are measured in-situ during the exposure of heavy ions.The experimental data shows that the changes in the reciprocal of the gain variation((1/β)) of 3DD155 transistors irradiated respectively by 25-MeV C,40-MeV Si,and 40-MeV Cl ions each present a nonlinear behaviour at a low fluence and a linear response at a high fluence.The(1/β) of 3DD155 BJT irradiated by 25-MeV C ions is greatest at a given fluence,a little smaller when the device is irradiated by 40-MeV Si ions,and smallest in the case of the 40-MeV Cl ions irradiation.The measured and calculated results clearly show that the range of heavy ions in the base region of BJT affects the level of radiation damage.     

Use of pH-Zone Refining Countercurrent Chromatography for Preparative Separation of Fangchinoline and Tetrandrine from Stephania tetrandra

pH-Zone-refining countercurrent chromatography with a multilayer coil planet centrifuge has been successfully used for separation of fangchinoline and tetrandrine from crude extracts of Stephania tetrandra. The two target compounds were completely resolved by use of the two-phase solvent system petroleum ether (60–90 °C)–ethyl acetate–methanol–water 5:5:1:9 (v/v), with 10 mm triethylamine in the organic stationary phase and 5 mm hydrochloric acid in the aqueous mobile phase. Separation of 3.5 g sample yielded 126 mg fangchinoline (LC purity >93%) and 249 mg tetrandrine (LC purity >95%). The structures of the compounds were confirmed by use of electrospray ionization mass spectrometry and ¹H NMR.     

Stochastic programming based capacity planning for semiconductor wafer fab with uncertain demand and capacity

Capacity planning is a challenging problem in semiconductor manufacturing industry due to high uncertainties both in market and manufacturing systems, short product life cycle, and expensive capital invest. To tackle this problem, this paper proposes a scenario-based stochastic programming model which considers demand and capacity uncertainties via scenarios, where the overall equipment efficiency is employed to describe the uncertain capacity for the first time. Based on the decentralized structure of tool procurement, production, stockout, and inventory decision-making processes, recourse approximation strategies are presented with varying degree of information share. The computational experiments show that the resulting tool set is robust enough to cope with the changes in capacity with the expected profits being maximized for different scenarios, and the scheme can generate pretty good solutions in reasonable computational time.     

A Frictional Heat Model of Planetary Roller Screw Mechanism Considering Load Distribution

Planetary roller screw (PRS), with higher thrust, higher load capacity, and higher speed, is the best choice of the transmission component of the servo system. However, spinning sliding of rollers and support bearings can cause frictional moments and frictional heat, which is an undesirable phenomenon. Besides, frictional heat will further result in high temperature that causes deterioration of lubrication and eventually lead to destruction of the mechanism. Therefore, it is important to predict frictional moments which result in frictional heat. In order to predict the magnitude of frictional heat of PRS mechanism and study the influence of structural parameters of thread and operating conditions on frictional heat, first, a frictional moment model of bearings is built, and frictional moments models of PRS considering the elastic hysteresis of material, the spinning sliding of the rollers, the viscosity of lubricating oil and the differential sliding of thread raceways are established in this paper, respectively. Second, heat generation models of bearing and PRS are presented, respectively. Finally, relationships between frictional heat in terms of operating conditions of PRS, contact angle, and helix angle of roller thread are investigated. The achievements of this project will provide theoretical basis for the design of PRS with lower frictional moments and higher transmission efficiency.     

目标激光脉冲一维距离成像研究

根据激光雷达方程及粗糙面脉冲波束散射理论,提出了目标激光脉冲后向散射回波功率即激光一维距离像的计算表达式,并获得斜板、球和圆锥一维距离像的具体形式.数值计算结果与粗糙平板和圆锥激光脉冲回波强度实验数据比较,两者符合良好.数据分析表明,激光一维距离像曲线能够较好反映目标的纵向几何外形信息.我们着重讨论了入射激光脉冲宽度与目标径向尺寸对距离像的影响.上述研究可为激光波段的目标特征提取和识别提供理论依据.     

Compact beam collimator for laser diode bar

A compact beam collimator for a laser diode (LD) bar fabricated by a simple method is presented. It consists of a single set of microlenses and a cylindrical lens, which are fabricated from SiO₂ rods using a fiber-drawing tower. The principle and parameter optimization of this device are investigated numerically using ZEMAX software and illustrated experimentally for a specific LD bar. It is shown that the output beam is well collimated in both the fast-axis and slow-axis directions; the beam quality is greatly enhanced via the redistribution of intensity in the two directions and by eliminating the fill factor for the LD bar.     

Nonuniformity correction algorithm with nonlinear model for infrared focal plane arrays

For the detector in infrared focal plane arrays (IRFPA) with a large dynamic range of response, a nonlinear model of response curve of the detector in IRFPA is introduced in this paper. With the model, the Kalman-filter nonuniformity correction (NUC) algorithm with linear model, developed by Torres and Hayat, is extended. In the extended algorithm, the raw image is translated into a linearized one firstly by directly employing a logarithm-based transformation. Then the linearized image is corrected by the Kalman-filter NUC algorithm with linear model, and the corrected linearized image is obtained. Finally the uniformity image of the original one is achieved by fulfilling an exponent transformation to the corrected linearized image. The presented algorithm not only inherits the advantage of the original algorithm that resolves the problem of the temporal drift in the gain and the bias in each detector by updating NUC parameters with information of the current scene, but also reduce the influence of the detector nonlinear response to the NUC performance, so it is suitable for IRFPA under large response-range. The NUC ability of the presented algorithm is demonstrated by experiments with real infrared image sequences.     

Slowing polar molecules using a wire Stark decelerator

We have designed and implemented a new Stark decelerator based on wire electrodes, which is suitable for ultrahigh vacuum applications. The 100 deceleration stages are fashioned out of 0.6 mm diameter tantalum and the array's total length is 110 mm, approximately 10 times smaller than a conventional Stark decelerator with the same number of electrode pairs. Using the wire decelerator, we have removed more than 90% of the kinetic energy from metastable CO molecules in a beam.     

Dispersion characteristics of nanometer-scaled silicon rib waveguides

<正>We investigate the dispersion properties of nanometer-scaled silicon waveguides with channel and rib cross section around the optical fiber communication wavelength and systematically study their relationship with the key structural parameters of the waveguide.The simulation results show that the introduction of an extra degree of freedom in the rib depth enables the rib waveguide more flexible in engineering the group velocity dispersion(GVD) compared with the channel waveguide.Besides,we get the structural parameters of the waveguides that can realize zero-GVD at 1550 nm.