基于BP算法神经网络的物理实验曲线拟合

介绍了人工神经元网络的基本原理和BP算法神经网络。将BP算法神经网络应用于物理实验中的幅频特性曲线拟合，在MATLAB下通过训练和仿真验证了应用BP算法神经网络拟合实验曲线的优越性。     

Evidence for a kaon-bound state K(-)pp produced in K(-) absorption reactions at rest

We have searched for a deeply bound kaonic state by using the FINUDA spectrometer installed at the e(+)e(-) collider DAPhiNE. Almost monochromatic K(-)'s produced through the decay of phi(1020) mesons are used to observe K(-) absorption reactions stopped on very thin nuclear targets. Taking this unique advantage, we have succeeded to detect a kaon-bound state K(-)pp through its two-body decay into a Lambda hyperon and a proton. The binding energy and the decay width are determined from the invariant-mass distribution as 115(+6)(-5)(stat)(+3)(-4)(syst) MeV and 67(+14)(-11)(stat)(+2)(-3)(syst) MeV, respectively.     

一种新的测定一维同核全相关的NMR技术

提出一种新的基于MDY混合脉冲的可测定一维同核全相关的核磁共振技术.称为一维自旋回波MDY相干转移(lD-SEMDY)实验.结果表明.它具有下列突出优点:一是不用Z-滤波技术就可以得到纯吸收型的一维全相关谱(lD-TOCSY).与同类技术相比,操作简便.可节省测定时间.应用范围较广;二是所测定亚谱中的信号归属通过改变混合时间和延迟时间可以得到确定;三是相干转移非常有效.远程磁化转移信号的灵敏度比较高,对弱偶合的自旋体系也可进行测定.以甙类化合物为例讨论了它在谱峰高度重叠的有机结构测定中的应用.     

Langendorff灌流心脏的31P NMR谱测定

测定了Langendorff灌流大鼠和兔心脏的³¹P NMR谱.观测到PCr、ATP、SP、P_i以及PME和GPC等含磷代谢物的共振峰,各谱峰之间实现了很好的分辨.在3~5min的累加时间内测得的图谱具有较好的S/N,可用于以上含磷代谢物的定量测定,以高能含磷化合物ATP和PCr相对峰强度以及冠脉流量的变化对灌流大鼠心脏代谢的稳定性进行了考察,结果表明,在本实验条件下大鼠心脏的能量储存至少可稳定2h,用所建方法以3min的时间间隔对同一大鼠心脏缺血21min及再灌注12min过程中心脏的³¹P NMR谱进行了连续跟踪测定,并初步观测了缺血及再灌注过程中心肌细胞内ATP、PCr与P_i之间的消长关系.     

大气弱湍流下星地光链路衰落特性影响因素分析

研究了弱湍流条件下星地光通信链路的衰落概率、平均衰落次数以及平均衰落时间3个重要参数的统计特性,并通过数值仿真分析了链路天顶角、光波长以及接收机海拔高度对链路衰落特性的影响。结果表明:减小天顶角和提高接收机探测灵敏度可以改善链路的衰落特性;1.55 m激光较0.85 m、1.06 m激光更适合于星地光通信;地面接收机应尽量建在2 000 m以上的高海拔地区。     

超薄前投激光显示系统研制

为了解决光学系统投影厚度过大问题,采用自由曲反射面结合非球面设计方法设计出超短距离、超广角投影显示系统,其屏幕投影距离小于20 cm。为解决激光色域系统转换,建立了激光三基色与荧光粉三基色色域变换与扩展的理论模型并搭建了基于DSP高速图像处理芯片为核心的颜色变化实时硬件处理试验开发系统。通过该系统可以调试不同颜色系统转换算法,验证转换模型的正确性,并为实现专用颜色转模块提供了开发平台。     

基于MSP430单片机的自动灌溉演示装置

介绍了基于MSP430F149单片机的自动灌溉演示系统的软硬件设计.该系统通过单片机控制温湿度传感器和光强传感器,实现对环境相对湿度、温度、光强实时采集与处理,演示自动灌溉植物.     

A 2-dimensional gradual period photonic heterostructure possessing omnidirectional band gap in visible range made by holography

A 2-dimensional gradual period photonic heterostructure was made with holography by use of non-uniform swelling effect of dichromated gelatin during processing. In this structure, the symmetric point group of triangle lattice was debased to C_2V from C_6V. Theoretical analysis and experimental results show that omnidirectional band gap in visible range can be achieved with this kind of heterostructure made by low refractive index materials.     

The study on neural contrast sensitivity function at temporal frequencies

The neural contrast sensitivity function (NCSF) of human eye at temporal frequencies is acquired with a new method in this paper. Firstly the human eye's contrast sensitivity function (CSF) at temporal frequencies is measured by means of travelling-wave stimuli, and the modulation transfer function (MTF) of the eye's optics is obtained by constructing the eye model of the subject. Then the NCSF at temporal frequencies is calculated with the two functions. It is shown that the overall value of the NCSF decreases as the temporal frequency increases. As the temporal frequency increases from 0 cycles per second (c/s) to 1 c/s, 16 c/s and 30 c/s, the NCSF curve changes from the band-pass shape to the low-pass, and then to almost monotonic variation. The attenuation factor of the NCSF, which represents the sensitivity of visual neural system to the temporal frequency, varies little as spatial frequency increases, while that of the CSF declines dramatically in the region of high spatial frequencies. Because it is the NCSF, rather than the CSF, that reflects the characteristics of visual neural system, the investigation of the NCSF at temporal frequency is more essentially.     

基于特征投影图的小麦近红外光谱变量选择方法研究

为了简化模型,提高模型预测精度,利用特征投影图(LPG)进行变量选择。对原始光谱进行连续小波变换(CWT),利用主成分分析(PCA)得到LPG,假定LPG中共线性光谱变量对建模作用相同,选出少数特征光谱变量建立预测模型,所得模型预测均方根误差(RMSEP)为0.345 4,优于其他建模方法,研究结果表明,LPG变量选择可有效简化近红外光谱模型,提高模型预测精度。