多个神经振子群网络的相位动力学编码

利用随机相变动力学理论研究运动认知的神经网络动力学模型．给出了感觉神经元集群、中间神经元集群和运动皮层神经元集群在耦合条件下相互作用、相位编码和数密度随时间的演化．探讨了神经网络在自发运动条件下以及在刺激条件下的神经网络动力学响应．通过数值模拟证实了（1）Walter J．Freeman提出的皮层动力学响应不能够编码外刺激信息的猜想;（2）串行的神经网络系统的神经编码具有节律编码的性质;（3）在中枢神经系统的调控中,神经抑制有其重要的作用．     

基于重要目标区的三维地形快速渲染方法

三维地形的显示需要绘制大量的三角形网格,为了提高地形显示速度目前广泛采取了三角形网格简化技术。针对弹道导弹作战区域地形的特殊性,提出了一种基于重要目标区的网格简化方法。从BMP位图读取地形高度信息,以四叉树保存网格数据,按照区域重要性静态确定地形网格疏密程度。并采用DirectX平台,实现了导弹战区三维地形显示,提高了渲染效率。     

Neuro-fuzzy speed control of traveling-wave type ultrasonic motor drive using frequency and phase modulation

This paper presents a Fuzzy Neural Network (FNN) control system for a traveling-wave ultrasonic motor (TWUSM) driven by a dual mode modulation non-resonant driving circuit. First, the motor configuration and the proposed driving circuit of a TWUSM are introduced. To drive a TWUSM effectively, a novel driving circuit, that simultaneously employs both the driving frequency and phase modulation control scheme, is proposed to provide two-phase balance voltage for a TWUSM. Since the dynamic characteristics and motor parameters of the TWUSM are highly nonlinear and time-varying, a FNN control system is therefore investigated to achieve high-precision speed control. The proposed FNN control system incorporates neuro-fuzzy control and the driving frequency and phase modulation to solve the problem of nonlinearities and variations. The proposed control system is digitally implemented by a low-cost digital signal processor based microcontroller, hence reducing the system hardware size and cost. The effectiveness of the proposed driving circuit and control system is verified with hardware experiments under the occurrence of uncertainties. In addition, the advantages of the proposed control scheme are indicated in comparison with a conventional proportional-integral control system.     

High resolution X-ray phase contrast synchrotron imaging of normal and ligation damaged rat sciatic nerves

This study was performed to apply synchrotron radiation (SR) imaging to a neuropathologic evaluation technique after treatment of peripheral nerve blocks. A phase contrast synchrotron images of normal and ligation damaged rat sciatic nerve were obtained with an 8 KeV monochromatic beam and 20-mum thick CsI(TI) scintillation crystal. The visual image was magnified using a 20x microscope objective and captured using an analog CCD camera. Obtained images were compared with conventional light microscopic findings from the same nerve samples. By using an edge enhancement effect of phase const with SR, we could easily discriminate each nerve fiber and identify the arrangement of nerve fibers within a whole thickness (about 1 mm in diameter) of peripheral nerve without sectioning and fixation. The composite SR image of a ligation damaged rat sciatic nerve sample showed that the response to nerve injury was different on each side of the site of injury. The SR image of damaged distal lesion showed destruction of neural microarchitecture and typical extensive Wallerian degeneration of nerve fibers as clearly as histologic image. We could get very detailed morphologic data for Wallerian degeneration of nerve fibers by using the SR imaging technique. We believe that the phase contrast synchrotron imaging has great potential as an imaging tool in the bioscience and medical science.     

基于正负理想点的导弹武器系统作战效能评估

讨论了目前导弹武器系统作战效能评估中的几点不足,提出用正负理想点法来评估导弹武器系统的作战效能.首先给出评估模型.其次,通过对具有典型意义的5种空舰导弹武器系统作战效能进行分析,给出应用示例,并对评估效果进行分析,得出结论.     

基于相空间重构的汇率预测研究

汇率在宏观经济政策、商业经营和个人决策制定上的作用越来越重要,使其成为了研究的热点。根据混沌动力系统的相空间延迟坐标重构理论,基于支持向量机的强大的非线性映射能力,提出了一种基于支持向量机回归的超短期汇率预测方法,并建立了模型,对美元港币的即时汇率进行了实证计算,且与BP神经网络模型进行了比较。结果表明,所建立的模型能很好地跟踪即时汇率的变化趋势,预测精度比较高且算法运行速度比BP神经网络模型快得多。     

基于FPGA硬件实现的谐波检测方法

针对现有系统对谐波检测实时性差和精度低的问题,介绍一种基于傅立叶变换和FPGA硬件实现的谐波检测方法.分析了谐波检测中影响测量精度的关键因素,采用数字锁相环来同步被测信号,以减小由非同步采样所产生的误差.基-4FFT 处理器的硬件设计采用全并行的乘法运算单元结构和并行的存储分配方法,最大限度地提高谐波检测的速度.数字锁相环和基-4 FFT 算法用VHDL语言设计实现,并用MAX plus Ⅱ软件进行仿真,仿真结果表明,所设计的数字锁相环可以很好地跟踪被测信号,在180ms时,误差仅为0.01Hz,很好地消除了非同步采样所引起的测量误差;采用所设计的基-4FFT运算器对给定的谐波数据进行运算,得到的谐波幅值和相位误差小于0.05%,运算时间仅为8μs.     

Structural instabilities and superconductivity in La-214 compounds

In La_2–x Ba _x CuO₄ (LBCO) the transition to a low-temperature tetragonal phase and the suppression of superconductivity occur at the carrier concentration p 1/8 per copper. We will discuss the roles of various material parameters that control this instability. An unusual lattice softening has been found by ultrasonic measurement on La_2–x Sr _x CuO₄ (LSCO). This softening is present only in an in-plane shearing mode and is ascribed to the growth of structural fluctuations in the normal state.These phenomena are closely related because both the structural change in LBCO and the applied strain in LSCO lift the degeneracy of in-plane oxygen sites. They clarify the importance of strong coupling between the normal-state electronic system and the lattice by a Peierls-type mechanism.     

拦截高速再入体的间歇控制弹道研究

针对测量角度和寻的过程的几何关系造成的观测力下降,以及精确制导与滤波器发散的矛盾,采用一种“间歇机动”制导与“修正增益伪测量滤波器“方案,并优选出了实现间歇机动的开关函数,使拦截高速再入体的命中精度大大提高。     

远洋追踪记

本文记述１９８０年５月,我国首次试验向南太平洋发射洲际运载火箭,远望１号、２号等１８艘舰船开赴落区进行弹道测量及打捞数据舱的经过,并论述了这次试验及激光测距取得成功的重要意义。