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61.
Ultraviolet (UV) light can be used in versatile applications ranging from photoelectronic devices to biomedical imaging. In the development of new UV light sources, in this study, stable UV emission at ≈350 nm is unprecedentedly obtained from carbon nanospheres (CNSs). The origin of the UV fluorescence is comprehensively investigated via various characterization methods, including Raman and Fourier transform infrared analyses, with comparison to the visible emission of carbon nanodots. Based on the density functional calculations, the UV fluorescence is assigned to the carbon nanostructures bonded to bridging O atoms and dangling –OH groups. Moreover, a twofold enhancement in the UV emission is acquired for Au‐carbon core‐shell nanospheres (Au‐CNSs). This remarkable modification of the UV emission is primarily ascribed to charge transfer between the CNSs and the Au surface.  相似文献   
62.
考虑了剪滞翘曲应力自平衡条件、剪切变形和剪力滞后效应等因素的影响,本文提出了一种对宽翼薄壁T形梁动力学特性的分析方法.分析中为了准确反应T形梁翼板的动位移变化,三个广义动位移被引入,且以能量变分原理为基础建立了T形梁动力反应的控制微分方程和自然边界条件,据此对T形梁的动力反应特性进行了分析,揭示了T形梁桥动力反应的规律.算例中,对比了考虑和不考虑剪滞翘曲应力自平衡条件对T形梁动力反应的影响,结果显示考虑剪滞翘曲应力自平衡条件的计算方法与有限元数值解吻合更好.  相似文献   
63.
With the rapid development of web service technology in these years, traditional standards have been matured during the process of service registry and discovery. However, it is difficult for service requesters to discover satisfactory web services. The reason for this phenomenon is that the traditional service organization mode lacks semantic understanding ability for service function interface. This paper proposes a novel approach to annotating web services. We first adopt domain ontology as a semantic context, and give our general framework of service semantic annotation. Then, interface concept mapping algorithm and service interface expansion algorithm are respectively presented in detail. Finally, the generation process of semantic web service repository is presented based on preceding algorithms. Simulation experiment results demonstrate that annotated web services by the proposed method can more satisfy requirements for service requesters than traditional ones by service matchmaking engine. It can get better service discovery effectiveness.  相似文献   
64.
主要从软件自动化测试在工作中的实际经验出发,探讨如何合理应用"软件自动化测试"这一测试手段.同时也简单介绍了软件自动化测试的定义、目的等概念,以及常见的一些自动化测试工具软件.另外从对软件自动化测试的一些认识误区的分析中,让大家意识到软件自动化测试的合理应用是软件开发过程中降本增效的关键.  相似文献   
65.
This paper presents an efficient planning and execution algorithm for the navigation of an autonomous rotary wing UAV (RUAV) manoeuvering in an unknown and cluttered environment. A Rapidly-exploring Random Tree (RRT) variant is used for the generation of a collision free path and linear Model Predictive Control(MPC) is applied to follow this path. The guidance errors are mapped to the states of the linear MPC structure by using the nonlinear kinematic equations. The proposed path planning algorithm considers the run time of the planning stage explicitly and generates a continuous curvature path whenever replanning occurs. Simulation results show that the RUAV with the proposed methodology successfully achieves autonomous navigation regardless of its lack of prior information about the environment.  相似文献   
66.
目的:了解医学生的上网情况。方法:采用"医学生上网调查问卷",在七个不同专业500名学生中进行问卷调查。结果:有95.16%学生上网,上网学生中30.25%每次上网3h以上;上网目的以聊天、多媒体娱乐和玩游戏为主。结论:青年群体是网上的主力军,应警惕大学生网上迷路,鼓励上网学生要以理智态度控制上网时间,老师和学校应给予学生上网以恰当的引导和教育。  相似文献   
67.
We present a type of single-hidden layer feed-forward wavelet neural networks. First, we give a new and quantitative proof of the fact that a single-hidden layer wavelet neural network with n + 1 hidden neurons can interpolate + 1 distinct samples with zero error. Then, without training, we constructed a wavelet neural network X a (x, A), which can approximately interpolate, with arbitrary precision, any set of distinct data in one or several dimensions. The given wavelet neural network can uniformly approximate any continuous function of one variable.  相似文献   
68.
69.
This paper identifies a property of delay-robustness in distributed supervisory control of discrete-event systems (DES) with communication delays. In previous work a distributed supervisory control problem has been investigated on the assumption that inter-agent communications take place with negligible delay. From an applications viewpoint it is desirable to relax this constraint and identify communicating distributed controllers which are delay-robust, namely logically equivalent to their delay-free counterparts. For this we introduce inter-agent channels modeled as 2-state automata, compute the overall system behavior, and present an effective computational test for delay-robustness. From the test it typically results that the given delay-free distributed control is delay-robust with respect to certain communicated events, but not for all, thus distinguishing events which are not delay-critical from those that are. The approach is illustrated by a workcell model with three communicating agents.  相似文献   
70.
Copy move forgery detection (CMFD) is one of the most active subtopic in forgery scheme. The methods of CMFD are divided into to block-based method and keypoint-based method in general. Compared with keypoint-based method, block-based method can detect undetectable detail without morphology segmentation. But many block-based methods detect the plain copy-move forgeries only. They have been incompetent to detect the post-processing operations such as various geometrical distortions, and then fail to detect the forgery regions accurately. Therefore, this paper presents an improved block-based efficient method for CMFD. Firstly, after pre-processing, an auxiliary overlapped circular block is presented to divide the forged image into overlapped circular blocks. The local and inner image feature is extracted by the Discrete Radial Harmonic Fourier Moments (DRHFMs) with the overlapped circular block from the suspicious image. Then, the similar feature vectors of blocks are searched by 2 Nearest Neighbors (2NN) test. Euclidean distance and correlation coefficient is employed to filter these features and then remove the false matches. Morphologic operation is employed to delete the isolated pixels. A series of experiments are done to analyze the performance for CMFD. Experimental results show that the new DRHFMs can obtain outstanding performance even under image geometrical distortions.  相似文献   
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