一种三维平板式图书扫描仪

分析了对低成本非破坏性扫描仪的需求,比较了现有图书扫描仪的应用现状,提出以书本表面形态曲线作为扫描路径的三维平板扫描仪,为各图书馆特色资源数字化工作提供了一种低成本无破坏的扫描设备。     

民勤连古城国家级自然保护区管理存在的问题与对策

概述了民勤连古城国家级自然保护区特殊的生态区位的重要性,总结了该保护区在建设初级阶段的生态环境和动植物资源现状,从法律体系、执法体系、管理体系、科研体系、基础建设、产业开发等方面分析了保护区管理存在的问题,着重在以法治区、宣传教育、自然保护、社区共管和资金投入等方面提出了对策与建议。     

基于主题词权重和句子特征的自动文摘

为获得高质量的自动文摘,在组合词识别算法的基础上,充分考虑词的频率、词性、词的位置、词长等因素,构建了一个词语权重计算公式,该公式能使表达主题的词和短语具有较高的权重.对句子权重的计算,则考虑了句子的内容、位置以及线索词的作用和用户偏好等.摘要的生成充分考虑了候选文摘句的相似性,避免了冗余信息的加入.对摘要的评估进行了从句子粒度到词语粒度的改进,提出了一种基于词语粒度的准确率和召回率计算方法.实验证明,该算法生成的自动文摘有着较高的质量,平均准确率达到77.1%.     

山水林田湖草生命共同体研究的知识图谱透视分析

中国的环境问题依然严峻,同时对生态文明建设日益重视,因此有必要对有关山水林田湖草生命共同体研究的变化特征进行分析,为未来的相关研究提供参考借鉴。本文运用知识图谱软件对中国知网（CNKI）收录的有关山水林田湖草生命共同体研究的文献的作者、发文机构、关键词等内容进行可视化分析。结果表明,山水林田湖草生命共同体研究成果逐渐增多,形成了少数核心作者群、核心研究机构和核心发文期刊,研究主题先后聚焦于生态文明建设、系统治理、流域治理等,而研究前沿主要聚焦于相关制度建设。     

Wigner-Ville distribution and cross Wigner-Ville distribution of noisy signals

The Wigner-Ville distribution （WVD） and the cross Wigner-Ville distribution （XWVD） have been shown to be efficient in the estimation of instantaneous frequency （IF）. But the statistical result of the IF estimation from XWVD peak is much better than using WVD peak. The reason is given from a statistical point of view. Theoretical studies show that XWVD of the analyzed signal can be estimated from XWVD of the noise-contaminated signal. The estimation is unbiased, and the variance is equal to that of noise. In this case, WVD cannot be estimated from W-VD of the noise-contaminated signal. Therefore, higher SNR is required when WVD is used to analyze signals.     

Algorithms for degree-constrained Euclidean Steiner minimal tree

A new problem of degree-constrained Euclidean Steiner minimal tree is discussed, which is quite useful in several fields. Although it is slightly different from the traditional degree-constrained minimal spanning tree, it is also NP-hard. Two intelligent algorithms are proposed in an attempt to solve this difficult problem. Series of numerical examples are tested, which demonstrate that the algorithms also work well in practice.     

Random testing for system-level functional verification of system-on-chip

In order to deal with the limitations during the register transfer level verification, a new functional verification method based on the random testing for the system-level of system-on-chip is proposed. The validity of this method is proven theoretically. Specifically, testcases are generated according to many approaches of randomization. Moreover, the testbench for the system-level verification according to the proposed method is designed by using advanced modeling language. Therefore, under the circumstances that the testbench generates testcases quickly, the hardware/software co-simulation and co-verification can be implemented and the hardware/software partitioning planning can be evaluated easily. The comparison method is put to use in the evaluation approach of the testing validity. The evaluation result indicates that the efficiency of the partition testing is better than that of the random testing only when one or more subdomains are covered over with the area of errors, although the efficiency of the random testing is generally better than that of the partition testing. The experimental result indicates that this method has a good performance in the functional coverage and the cost of testing and can discover the functional errors as soon as possible.     

Robust H2 control for uncertain sampled-data systems

A new approach is proposed for robust H2 problem of uncertain sampled-data systems. Through introducing a free variable, a new Lyapunov asymptotical stability criterion with less conservativeness is established. Based on this criterion, some sufficient conditions on two classes of robust H2 problems for uncertain sampled-data control systems are presented through a set of coupled linear matrix inequalities, Finally, the less conservatism and potential of the developed results are illustrated via a numerical example.     

Adaptive broadband beamformer for nonuniform linear array based on second order cone programming

Adaptive broadband beamforming is a key issue in array applications. The adaptive broadband beamformer with tapped delay line (TDL) structure for nonuniform linear array (NLA) is designed according to the rule of minimizing the beamformer's output power while keeping the distortionless response (DR) in the direction of desired signal and keeping the constant beamwidth (CB) with the prescribed sidelobe level over the whole operating band. This kind of beamforming problem can be solved with the interior-point method after being converted to the form of standard second order cone programming (SOCP). The computer simulations are presented which illustrate the effectiveness of our bearaformer.     

下一代密集WLAN网络干扰管理机制

在密集高效无线局域网部署场景中,针对传统802.11协议造成用户公平性差和吞吐量低的问题,提出一种以用户为中心的资源配置方法。该方法通过对用户进行识别分类,以用户为中心配置信道和功率,在保证用户公平性的前提下,最大化网络吞吐量。提出的功率控制机制和用户识别方法可以很简单的应用于现有无线局域网系统中。仿真结果表明,提出的资源配置方法平均提升单位基本服务集吞吐量47.3%,干扰最严重的基本服务集的吞吐量提升190%,每个基本服务集的边缘用户的吞吐量平均提升约74.3%。