基于FPGA的TDM over IP的设计

设计一种TDM over IP的技术系统。该系统用FPGA将E1数据包通过串并转换到千兆以太网数据包,经IP网传输到终端设备,再通过并串转换将以太网数据包转换成E1数据包完成传输。经过软件和硬件测试验证了此系统在千兆以太网上传输的可行性,系统没有出现误码,固有输出抖动是0.55UI,最大峰值抖动指标均满足ITU-G.823标准要求。     

医用钴基合金的组织结构及耐腐蚀性能

以锻造CoNiCrMo，CoCrMo和CoCrMoC台会为研究对象，通过金相观察，XRD分析和耐腐蚀试验，研究了3组合金在不同热处理条件下的显微结构，相成分及在Hi同溶液中的耐腐蚀性能。结果表明：2组锻造合金的再结晶温度都是1000℃，且晶粒尺寸随着固溶温度升高和时效时间延长而逐渐变大。3组试样在NaCl溶液中为钴基合金典型的阳极极化曲线；在Hanks’溶液中均有一个二次钝化行为，且锻造CoNiCrMo合金的二次钝化区域较窄，而其他2组合金则较宽；在含柠檬酸三钠的溶液中过钝化电位降低，柠檬酸盐的存在降低了含金的耐腐蚀性能。热处理对合金的耐腐蚀性能影响不大。     

稀土添加剂在镀硬铬中的应用

介绍了标准镀铬液中加入稀土添加剂进行低铬酸镀硬铬工艺及应用生产情况,以及取得的经济效益。     

论现金流量下的企业财务风险防范和控制

1 引言 对于企业来说,现金流量一般是以收付实现制为基础的,它集中反映的信息一般是企业真实的财务现金收入与现金支出,避免在权责发生制下,由于企业资产和负债的确认存在多种不同的方法,最终使得对同一会计事项产生出很多种不同会计信息的可能性,便于该企业进行与本企业各个时期的、各个企业的现金流量信息进行综合的比较和分析,为企业合理组织财务现金调度、风险控制、预测、决策提供比较可靠的依据.     

TAPI软电话通信系统的模块化设计

首先分析了TAPI协议的结构、通信编程原理和编程应用环境,重点介绍了TAPI协议的层次化模型结构及其模块化设计方法,该方法可以对进一步研究和开发TAPI软电话应用产品提供借鉴。     

Locally linear discriminant embedding: An efficient method for face recognition

In this paper an efficient feature extraction method named as locally linear discriminant embedding (LLDE) is proposed for face recognition. It is well known that a point can be linearly reconstructed by its neighbors and the reconstruction weights are under the sum-to-one constraint in the classical locally linear embedding (LLE). So the constrained weights obey an important symmetry: for any particular data point, they are invariant to rotations, rescalings and translations. The latter two are introduced to the proposed method to strengthen the classification ability of the original LLE. The data with different class labels are translated by the corresponding vectors and those belonging to the same class are translated by the same vector. In order to cluster the data with the same label closer, they are also rescaled to some extent. So after translation and rescaling, the discriminability of the data will be improved significantly. The proposed method is compared with some related feature extraction methods such as maximum margin criterion (MMC), as well as other supervised manifold learning-based approaches, for example ensemble unified LLE and linear discriminant analysis (En-ULLELDA), locally linear discriminant analysis (LLDA). Experimental results on Yale and CMU PIE face databases convince us that the proposed method provides a better representation of the class information and obtains much higher recognition accuracies.     

Web proxy cache replacement scheme based on back-propagation neural network

Web proxy caches are used to reduce the strain of contemporary web traffic on web servers and network bandwidth providers. In this research, a novel approach to web proxy cache replacement which utilizes neural networks for replacement decisions is developed and analyzed. Neural networks are trained to classify cacheable objects from real world data sets using information known to be important in web proxy caching, such as frequency and recency. Correct classification ratios between 0.85 and 0.88 are obtained both for data used for training and data not used for training. Our approach is compared with Least Recently Used (LRU), Least Frequently Used (LFU) and the optimal case which always rates an object with the number of future requests. Performance is evaluated in simulation for various neural network structures and cache conditions. The final neural networks achieve hit rates that are 86.60% of the optimal in the worst case and 100% of the optimal in the best case. Byte-hit rates are 93.36% of the optimal in the worst case and 99.92% of the optimal in the best case. We examine the input-to-output mappings of individual neural networks and analyze the resulting caching strategy with respect to specific cache conditions.     

张家界机场气象预报指标诊断系统

张家界荷花机场气象预报室从业务需要出发,编制了一套指标诊断系统,应用于实际业务中,对提高预报的准确性、做好日常航空飞行的气象保障工作具有较好的指导意义。系统采用可视化编程,引进气象学诊断分析相关原理方法,使系统本身具有自动性、适用性和可再开发性等特点。     

Controller design for flexible structure vibration suppression with robustness to contacts

Model-based feedback control of vibration in flexible structures can be complicated by the possibility that interaction with an external body occurs. If not accounted for, instability or poor performance may result. In this paper, a method is proposed for achieving robust vibration control of flexible structures under contact. The method uses robust linear state feedback, coupled with a state estimation scheme utilizing contact force measurement. Uncertain contact characteristics are modelled by a sector-bounded non-linear function, such that state feedback gains can be synthesized using a matrix inequality formulation of the Popov stability criterion. A separation theorem is used to establish a robust H₂ cost bound for the closed loop system. Experimental results from a multi-mode flexible structure testbed confirm that vibration attenuation and stability can be maintained over a broad range of contact characteristics, in terms of compliance and clearance.     

Optimal experimental design and some related control problems

This paper traces the strong relations between experimental design and control, such as the use of optimal inputs to obtain precise parameter estimation in dynamical systems and the introduction of suitably designed perturbations in adaptive control. The mathematical background of optimal experimental design is briefly presented, and the role of experimental design in the asymptotic properties of estimators is emphasized. Although most of the paper concerns parametric models, some results are also presented for statistical learning and prediction with nonparametric models.