Molecular alterations in tumorigenic human bronchial and breast epithelial cells induced by high LET radiation.

Carcinogenesis is a multi-stage process with sequence of genetic events governing the phenotypic expression of a series of transformation steps leading to the development of metastatic cancer. In the present study, immortalized human bronchial (BEP2D) and breast (MCF-10F) cells were irradiated with graded doses of either 150 keV/micrometer alpha particles or 1 GeV/nucleon 56Fe ions. Transformed cells developed through a series of successive steps before becoming tumorigenic in nude mice. Cell fusion studies indicated that radiation-induced tumorigenic phenotype in BEP2D cells could be completely suppressed by fusion with non-tumorigenic BEP2D cells. The differential expressions of known genes between tumorigenic bronchial and breast cells induced by alpha particles and their respective control cultures were compared using cDNA expression array. Among the 11 genes identified to be differentially expressed in BEP2D cells, three (DCC, DNA-PK and p21(CIP1)) were shown to be consistently down-regulated by 2 to 4 fold in all the 5 tumor cell lines examined. In contrast, their expressions in the fusion cell lines were comparable to control BEP2D cells. Similarly, expression levels of a series of genes were found to be altered in a step-wise manner among tumorigenic MCF-10F cells. The results are highly suggestive that functional alterations of these genes may be causally related to the carcinogenic process.     

激光外差干涉仪光电信号处理方法及特点

叙述和分析了外差激光干涉光电信号处理主其特点，指出了它们各自的应用范围，同时介绍了一处新型的光电信号处理方法，它不仅使外差干涉仪用于动态测量，而且可以同时实现高分辩率测量 。     

改进的次时间最优控制

本文在[1][2]基础上进一步探讨了次时间最优控制的改进问题,深入地阐明了次时间最优控制的某些特性后,提出了一个新的改进的设计方法。按照这种方法设计控制系统,不但实用而且可以大幅度提高次时间最优控制的最优性。并用实例比较了各种方法,证明了本文提出的方法的优越性。本文提出的方法应用于工程设计,对于提高系统的最优性是非常有效的。     

Flutter analysis of an airfoil with bounded random parameters in incompressible flow via Gegenbauer polynomial approximation

The effects of parameter uncertainty on the flutter characteristics of a two-dimensional airfoil in an incompressible flow were investigated through Gegenbauer polynomial approximation. The uncertain parameters, such as the linear and cubic pitch stiffness coefficients are modeled as bounded random variables with λ-PDFs (probability density functions). With the aid of Gegenbauer polynomial approximation, the two-dimensional stochastic airfoil system is transformed at first into its equivalent deterministic one. Then the Hopf-bifurcation point is determined through the equivalent deterministic system, and the onset of the flutter, together with the flutter frequency against the probability density distribution parameter and the intensity of the random variable is explored. In addition, the ranges of the peak pitch and plunge responses against the flight speed and the PDFs of the peak pitch response are obtained. Numerical results show how the probability density distribution parameters and the intensities of random parameters affect the flutter onset speed, flutter angular frequency, the upper and lower boundaries of peak responses, and the PDFs of peak responses.     

滚珠丝杠螺距误差补偿法提高数控机床定位精度的研究

在详细论述、对比了实现数控机床滚珠丝杠螺距误差补偿的硬件、软件方法的原理基础上,对滚珠丝杠螺距误差软件补偿法可有效提高数控机床的定位精度进行了试验验证。     

1/spl phi/ 3W grid-connection PV power inverter with partial active power filter

This paper presents a single-phase three-wire (1/spl phi/ 3W) grid-connection photovoltaic (PV) power inverter with a of partial active power filter (PAPF) feature, which can not only deal with PV power but filter current harmonics and improve power factor. Once the processed power exceeds the switch ratings, the inverter can reduce its output reactive power and harmonic power, while still supplying the maximum real power generated by the PV arrays. In the derivation of control laws, a limit circle is defined to confine the output power of the inverter. To determine the power that the inverter can process, the instantaneous reactive power of a 1/spl phi/ 3W system is defined and used to calculate reactive power, which can avoid complex detections of phase angle and magnitude of the fundamental component of a nonlinear load current. Simulation results and experimental measurements have verified the proposed algorithm and the feasibility of the inverter.     

Aperture error mitigation via local-state estimation for frequency-based emitter location

This paper considers the problem of locating a stationary coherent emitter via a single moving platform making frequency measurements in the presence of aperture state uncertainty. It is shown that the estimated emitter location is most sensitive to the receiving aperture velocity uncertainty. The required aperture velocity accuracy is determined through a noninfinitesimal perturbation analysis. A solution to location accuracy enhancement with a minimal hardware addition is attempted. It is shown that this can be achieved by mounting a high-resolution tri-axis microelectromechanical systems (MEMS) accelerometer at the aperture to measure its velocity, which can deviate significantly from that estimated by the on-board navigation system. The Doppler shifts of the GPS signal carrier frequency, whenever it can be acquired through the aperture, are also considered as a way to aid the aperture velocity measurement. A decentralized, federated processing method for the aperture velocity estimate referenced at the aperture, integrating all measurement data, is presented. An upper bound for the error of aperture velocity estimate is derived. The potential for significant accuracy enhancement for emitter location is demonstrated.     

空间材料质量损失和易挥发可凝物长期预测方法

文章从基本理论及相应试验两方面详细介绍了欧洲 ESA 空间研究技术中心(ESTEC)材料部建立的空间材料质量损失和易挥发可凝物长期预测的方法,并确认此种预测方法具有极高准确度。     

毕棚沟 一路走过

梦是对无限、永远的可能的相信，而现实并不……黑、白棋总是在棋盘上腾转挪移，而黑、白并不……[编者按]     

四维下降飞行技术的研究与仿真：定常航迹角法下降剖面解算

本文研究的是四维飞行性能管理系统的核心环节－飞机在终端区域内的四维下降技术，首先探讨了基于常值航迹角的定常Ｍ数／指示空速下降飞行技术，论述了其高度剖面的构成与特点，通过尤拉积分方法求解飞机运动方程，实现了高度冲面的解算。其次开发了对速度剖面的迭代过程，选取原则及方法。本文在进行理论分析的同时，还开发了满意的仿真软件，一了其应用价值。