半导体激光器干扰CCD光电探测器的实验研究

激光干扰是对抗精确制导武器,保卫自己目标的重要方式,通过饱和可见光CCD相机的整幅图像,使之无法对目标进行侦察.文章探讨了用半导体激光器致眩CCD相机的实验方案,分析实验现象,可以得出随着CCD积分时间的增加,CCD更容易达到饱和;每次达到软损伤的驱动电流都在7.2A左右     

采用图像特征的激光干扰跟踪效果评估

对于广泛应用于图像识别和跟踪的激光主动成像系统,激光干扰是影响该类系统性能的一个重要因素。激光干扰使系统中的光电成像元件达到饱和或损伤,在探测视场中出现光斑,从而使跟踪算法无法准确分辨目标和光斑。因此,分析并评估激光对主动成像系统的干扰效果是避免干扰的前提,同样也是重要的环节。提出一种基于图像特征的边缘相似度(ESIM)评价算法,该算法通过模板匹配确定图像的目标区域,并比较原始图像和干扰图像目标区域的亮度、对比度和边缘清晰度差异,得到归一化的评价指标,作为对激光干扰效果的评估标准。实验中分别采集了不同干扰功率和不同光斑位置的激光干扰图像,并利用相关跟踪和形心跟踪方法对目标进行跟踪,运用本文提出的ESIM算法从图像特征角度对干扰跟踪效果进行评估,结果证明ESIM能够合理评估干扰图像的失真程度,并可以较好地反映激光对主动成像系统跟踪性能的影响。     

基于图像特征相关度的激光干扰卫星效果评估

针对激光干扰光学成像卫星效果难以评估的问题,借鉴图像处理相关理论,将干扰前后卫星图像特征相关度作为评估指标,并采用HVS(人眼视觉系统)对指标进行修正,利用基于一致相邻度熵权的综合赋权方法,建立激光干扰效果综合评估模型。运用模型对受激光干扰条件下的卫星图像进行评估,得到的结论既能客观地反映激光干扰的实际效果,又能与人的主观感受保持较好的一致性,验证了模型在激光干扰光学成像卫星效果评估方面的适用性和科学性。     

Arbitrary real-order cost functions for signals and systems

This work focuses on a new type of cost function based on fractional operators. To do so, the concept of definite integral is extended to arbitrary real-order. Some properties of this new fractional-order definite integral are studied and a fractional-order Barrow's rule is proposed. It is illustrated by an example (the design of an IIR filter) how this new kind of cost function can be a valuable tool in problems where optimal design methods are involved.     

高次数弹性函数的构造

给出了一种直接构造弹性函数的方法, 得到了次数大于m的n个输入m个输出弹性度为t的函数,并且在相同次数下得到了目前非线性度最高的函数,而且满足扩散准则同时给出了它的计数。用这种方法构造的弹性函数易于计算机实现。     

CDMA2000网络升级期待平滑过渡

CDMA2000技术衍生于窄频CDMA One标准,可从原有的CDMA One结构直接升级到3G,也称为CDMA Multi-Carrier,由美国高通北美公司为主导提出,是全球部署范围最广泛的3G技术之一.据CDMA发展集团(CDG)统计,全球已有分布在105个国家和地区的251家运营商选择CDMA2000提供未来的3G服务.     

Exact correlation functions for non-Markovian laser phasefluctuations

A new model describing laser noise in terms of non-Markovian stochastic phase jumps has been introduced by A.G. Kofman et al. (1988, 1990). An exact expression for the correlation function for the electric field is obtained. This expression, valid for all possible values of the parameters of the stochastic process, reduces to approximations reported by B.R. Mollow (1969). A procedure is described for the inverse problem of determining the stochastic parameters from measured data for real lasers     

激光作业危害评价

本文报道了三种激光作业的危害评价方法和结果,并提出需要采取的防护措施。     

Convex cost functions in blind equalization

Existing blind adaptive equalizers that use nonconvex cost functions and stochastic gradient descent suffer from lack of global convergence to an equalizer setup that removes sufficient ISI when an FIR equalizer is used. The authors impose convexity on the cost function and anchoring of the equalizer away from the all-zero setup. They establish that there exists a globally convergent blind equalization strategy for 1D pulse amplitude modulation (PAM) systems with bounded input data (discrete or continuous) even when the equalizer is truncated. The resulting cost function is a constrained l₁ norm of the joint impulse response of the channel and the equalizer. The results apply to arbitrary linear channels (provided there are no unit circle zeros) and apply regardless of the initial ISI (that is whether the eye is initially open or closed). They also show a globally convergent stochastic gradient scheme based on an implementable approximation of the l₁ cost function     

On the degree of completeness of cryptographic functions

This paper discusses the degree of completeness of cryptographic functions, which is one of the cryptographic criteria should be considered in the design of stream ciphers. We establish the re- lationships between the degree of completeness and other cryptographic criteria. For resilient Boolean functions, a method to enhance the degree of completeness is proposed, while the nonlinearity and the algebraic degree do not decrease. Moreover, two constructions of resilient functions are provided, which have optimal degree of completeness, high nonlinearity, and high algebraic degree.     

Reliability evaluation for Blu-Ray laser diodes

With this paper we describe an extensive analysis of the reliability of InGaN-based laser diodes, emitting at 405 nm. These devices have excellent characteristics for application in the next-generation optical data storage systems. The analysis aims at describing the degradation process, as well as at investigating the role of current in determining the degradation rate. The results obtained within this paper suggest that the degradation of the laser diodes is correlated to the increase in the non-radiative recombination rate, with subsequent worsening of the optical properties of the devices. Furthermore, our findings support the hypothesis that current is the main driving force for degradation, while temperature and optical power play only a limited role in determining the degradation kinetics.     

Technique for direct evaluation of parameter sensitivity functions

A method is presented for the determination of parameter sensitivity functions of a simple feedback system from measured response data obtained during a step test. Results of simulation studies and a practical implementation involving a synchronous-generator-excitation system are presented.     

Minimal cost one-dimensional linear hybrid cellular automata of degree through 500

This letter is a supplement of the table of the minimal cost one-dimensional linear hybrid cellular automata with the maximum length cycle by Zhang, Miller, and Muzio [IEE Electronics Letters, 27(18):1625–1627, August 1991].This work was supported in part by Research Grants and Postgraduate Scholarships from the Natural Sciences and Engineering Research Council of Canada and by an equipment loan from the Canadian Microelectronics Corporation.     

Contact angle evaluation for laser cleaning efficiency

A laser cleaning technique using an excimer laser is introduced to remove the photoresist on a Si wafer surface and its cleaning characteristics have been investigated. To analyse the cleaning efficiency quantitatively, a scanning electronic microscope, energy dispersive spectroscope, surface scanner and contact angle measurement were employed. Among these methods, it was confirmed experimentally that the contact angle measurement could be applicable to analyse the laser cleaning efficiency effectively owing to its speed of measurement and low measurement cost.     

Effective method for evaluation of semiconductor laser quality

The measurements of one hundred 1.3 μm planar buried crescent (PBC) structure InGaAsP/InP lasers demonstrate that parameters given by the electrical derivative of varied temperature and the variation of the parameters with temperature can be used to appraise the quality and reliability of semiconductor lasers effectual. By measurement of electrical derivative curves one can evaluate the quality of epitaxial wafer and chip, find the problems in the material and the technology, offer the useful information on increasing the quality and improving the technology of devices.     

Optimal partition of QoS requirements with discrete cost functions

The future Internet is expected to support applications with quality of service (QoS) requirements. To this end, several mechanisms are suggested in the IETF; the most promising among them is DiffServ. An important problem in this framework is how to partition the QoS requirements of an application along a selected path. The problem which is, in general, NP-complete, was solved for continuous convex cost functions by Lorenz and Orda (see IEEE/ACM Trans. Networking. vol.6, p.768-78, 1998 and Proc. IEEE INFOCOM'99, p.246-53, 1999). This paper concentrates on discrete cost functions, which better model the existing and upcoming mechanisms in the Internet. We present efficient exact and approximated solutions for various conditions of the problem. We also show that although the more complex problem of QoS sensitive routing with discrete cost functions is hard, it has a fully polynomial approximation scheme     

Single-quantum-well laser with 11.2 degree transverse beam divergence

The authors report the operation of a single-quantum-well laser vertically integrated with four passive waveguides to achieve a record low beam divergence of 11.2 degrees . While the beam divergence is reduced by a factor of four when compared with a single-quantum-well laser, the threshold current increases by a factor of three. Analysis shows that it is possible to reduce the threshold current further while maintaining the same low beam divergence.<>     

CO2激光的偏振度与模式

本文用一种简便方法,使CO2激光通过一个可绕光轴旋转的布氏窗口,测定布氏窗口在不同转角下的激光反射及透射强度,从而可知该激光的偏振度.同时定性地研究了在不同放电电流下的输出激光模式与偏振度的关系.     

对一种手持激光测距仪的安全测试与评价

本文报导了用辐照量测试及动物实验的方法,对一种手持激光测距仪的安全指标进行了测试与评价.给出了可能致伤边界与安全距离.     

Spectral characterization of Boolean functions satisfying k degree propagation criteria

This paper discusses spectral characterization of Boolean functions satisfying k degree propagation criteria and satisfying k order strict avalanche criterion respectively. Meanwhile, introduces the generalized e–k degree propagation criteria and gives its spectral characterization.