基于图像内容及底层特征的敏感图像检测方法

内容安全是信息安全领域中的一个新兴且重要的研究方向.敏感图像分析与监控是该方向的一个重要研究分支,近年来愈来愈受到关注.然而,由于其研究起步较晚且图像本身所具有的复杂多样性,相对来说,目前已有的研究成果还比较少且性能上也有待于进一步提升,为此,本文提出了一种新的敏感图像分析检测方法.该方法从基于图像内容分析和基于图像底层特征分析两个方面进行综合分析检测,在基于内容分析方面,通过分析图像是否含有大量的皮肤区域来初步检测敏感图像;在基于图像底层特征分析方面,通过颜色直方图矢量和颜色聚合矢量提取图像的颜色及空间信息,并在此基础上利用SVM进行分类,从而实现敏感图像的初步检测;最后,对上述两方面的初步检测结果进行综合判决,实现敏感图像的最终检测.仿真实验结果出示了该新方法的有效性.     

Design of Distributed Beamforming for Dual‐Hop Multiple‐Access Relay Networks

This paper studies a dual‐hop multiple‐access relay network where two independent source nodes transmit information to a common destination node with the aid of multiple single‐antenna amplify‐and‐forward relays. Each relay node is subject to an individual power constraint. We focus on the design of distributed beamforming schemes for the relays to support the transmission rate requirements of the two sources. To this end, we first characterize the achievable rate region for this network via solving a sequence of corner point optimization problems proposed in this paper. We also develop several low‐complexity suboptimal schemes in closed form. Two inner bounds of the achievable rate region are theoretically shown to be approximately optimal in two special scenarios. Finally, numerical results demonstrate the effectiveness of our proposed approaches.     

High‐Performance Dual‐Circularly Polarized Reflector Antenna Feed

This paper presents a high‐performance dual‐circularly polarized feed employing a dielectric‐filled circular waveguide. Novel features are incorporated in the proposed feed, such as a dielectric rod radiator for high gain and good impedance matching; dual quarter‐wave chokes for low axial ratio over wide angles and for low back radiation; an integrated septum polarizer; and two end‐launch‐type coaxial‐to‐waveguide transitions. The proposed feed shows excellent performance at 5.0 GHz to 5.2 GHz.     

Decision Support for DCs Location and Distribute Range Planning: Case Study in Asia-Pacific Region

A major concern is to locate manufacturing plants and/or distribution centers to serve the needs of consumers widely and rapidly with reasonably distributive cost and flexible delivery time. The purpose of this research is to help enhance a decision support for three distribution center locations with different ranges of area in order that the distributors are able to serve appropriately the retailers in twelve large cities or capitals of the nine countries in Asia-Pacific region. The researcher applies the theory of supply chain and logistics management systems with Excel, Visual Basic and Genetic Algorithms programs to find the research results. The research results revealed that the interfaces of Excel, Visual Basic, and Genetic Algorithms programs helped decision support in distribution range selection for 3 distribution center locations. Each of which had different ranges of area for distribution with a rapidly, flexibly distributed time. However, variables resulting in a decision-making should be adjusted under certain circumstances for more reliable, specific needs.     

“数字信号处理”中重叠保留法的证明

重叠保留法是计算一个短序列与一个无限长序列线性卷积的有效方法。就我们所知,多数《数字信号处理》教材详细叙述了重叠保留法的步骤,有些教材还从线性卷积与循环卷积的关系出发给出了重叠保留法的原理,笔者认为这种解释不够清楚、也不够严谨。本文给出了一个较为严谨而准确的证明。     

基于均匀圆阵的近场源三维参数估计

基于均匀圆阵,提出一种近场源距离-方位角-俯仰角联合估计算法。利用阵元观测数据,构造一组高阶累积量矩阵,通过矩阵联合对角化技术得到阵列流形矩阵的估计。根据阵列流形矩阵的估计以及近场和远场条件下方位角相同的结论,获得方位角的估计。利用阵列流形矩阵和方位角的估计,得到距离和俯仰角的估计。该方法无需二维频域峰值搜索或参数配对。计算机仿真验证了算法的有效性。     

反常衍射近似在测量圆柱形粒子粒径分布中的应用

在光全散射法颗粒粒径测量中,基于米氏(Mie)理论的计算方法只能求出均匀球形粒子的消光系数,而且计算复杂。通过反常衍射近似(ADA)代替米消光系数,可以简化粒径分布的反演过程。对使用反常衍射近似方法计算圆柱形粒子消光系数的可行性以及限制条件进行深入的研究,并在非独立模式算法下,采用遗传算法反演粒径分布。仿真结果表明,当粒子的相对折射率在一定范围内时,利用反常衍射近似反演圆柱形粒子的粒径分布是完全可行的,反演结果稳定、可靠。对消光值测量结果加入3％相对误差时,反演误差为5．7％。该方法具有简单、直观、计算速度快等优点,适合颗粒粒径的在线测量。     

TD-LTE网络结构评估方法研究及预规划分析

TD-LTE作为同频组网系统,网络结构对其无线网络质量有着重要的影响。而在基于TD-SCDMA或GSM现网基础上进行TD-LTE建设时,会由于传统网络结构无法达到TD-LTE同频组网结构要求而造成网络质量下降。对此,本文提出了一种TD-LTE网络结构评估方法,通过对TD-SCDMA及GSM现网数据进行分析预测得到TD-LTE网络性能及其弱覆盖、重叠覆盖、干扰小区等网络结构指标。该方法可以对TD-LTE网络性能进行准确的评估,从而提升网络结构评估的准确性和实用性。     

基于特征区域分割的立体视频视觉舒适度评价方法

为准确反映人眼在观看立体视频过程中的视觉舒适程度,提出了一种基于特征区域分割的立体视频视觉舒适度评价方法。首先自适应地分割提取出立体视频序列中的人眼的感兴趣区域,以及相邻帧间的运动区域,然后结合深度感知理论和空间合并技术,对视觉舒适度这一特征量进行建模,最后实现对立体视频视觉舒适度的评定。实验结果表明,使用本文的方法对立体视频视觉舒适度进行评价,可以很好的模拟人眼直接观测的视觉感受,对于视觉舒适度的研究具有重要的参考价值。     

Necessary and Sufficient Stability Criterion and New Forbidden Region for Load Impedance Specification

A necessary and sufficient impedance stability criterion for the DC Distributed power system （DPS） is proposed in small-signal sense, which has no conservativeness when compared with other stability criteria. This paper discusses the stability margin and gives it a definition for the round forbidden region. The reasons why the stability margin varies at different interfaces are also discussed in this paper. With the impedance stability criterion and stability margins considered, the sector forbidden region, which is a new forbidden region and can be easily calculated in the Bode diagram, is proposed to solve the calculation problem of the round forbidden region in engineering application. This paper also provides examples and simulations to verify the necessary and sufficient impedance stability criterion and the proposed sector forbidden region for the load impedance specification.