共查询到20条相似文献，搜索用时 250 毫秒
1.
Design patterns are micro architectures that have proved to be reliable,robust and easy to implement.Detecting design pattern from source code of object-oriented system can help a designer,a developer or a maintainer to understand the software system.In this paper,a new method is provided which can detect design patterns from source code combining both static and dynamic analysis.To acquire the run-time dynamic information of software systems,a code instrumentation method is adopted.At the same time,all static and dynamic information is presented in UML diagrams format.The pattern detection process and its detection results are visual and interactive.This method is tested on a call center and a traffic simulation system.Experimental results prove that the method is effective in design patterns detection. 相似文献
2.
The cumulative sum （CUSUM） algorithm is proposed to detect the selfish behavior of a node in a wireless ad hoc network. By tracing the statistics characteristic of the backoff time between successful transmissions, a wireless node can distinguish if there is a selfish behavior in the wireless network. The detection efficiency is validated using a Qualnet simulator. An IEEE 802.11 wireless ad hoc network with 20 senders and 20 receivers spreading out randomly in a given area is evaluated. The well-behaved senders use minimum contention window size of 32 and maximum con- tention window size of I 024, and the selfish nodes are assumed not to use the binary exponential strategy for which the contention window sizes are both fixed as 16. The transmission radius of all nodes is 250 m. Two scenarios are investigated： a single-hop network with nodes spreading out in 100 m~100 m, and all the nodes are in the range of each other; and a multi-hop network with nodes spreading out in 1 000 m~ 1 000 m. The node can monitor the backoff time from all the other nodes and run the detection algorithms over those samples. It is noted that the threshold can significantly affect the detection time and the detection accuracy. For a given threshold of 0.3 s, the false alarm rates and the missed alarm rates are less than 5%. The detection delay is less than 1.0 s. The simulation results show that the algorithm has short detection time and high detection accuracy. 相似文献
3.
To improve the sensitivity of protein microarray, a prism surface replaces the surface of the common microscope slide. The protein targets arrayed on the surface are hybridized and labelled by fluorescent probes. Evanescent excitation occurs when the convergent laser reaches the surface, and a photomultiplier tube detects the emitted fluorescent signal. A two-dimensional actuator scans the whole surface to achieve planar laser excitation and fluorescence collection. The penetration depth of the evanescent field into the protein targets is only some hundred nanometers and can be controlled by different incident angle of the laser beam, so the undesired background signals are reduced dramatically and the detection sensitivity is improved by a factor of 50 to 100 comparing to confocal excitation. This approach can detect low abundance analytes without signal amplification. 相似文献
4.
Intrusion detection using rough set classification 总被引：2，自引：0，他引：2
Recently machine learning-based intrusion detection approaches have been subjected to extensive researches because they can detect both misuse and anomaly. In this paper, rough set classification (RSC), a modern learning algorithm, is used to rank the features extracted for detecting intrusions and generate intrusion detection models. Feature ranking is a very critical step when building the model. RSC performs feature ranking before generating rules, and converts the feature ranking to minimal hitting set problem addressed by using genetic algorithm (GA). This is done in classical approaches using Support Vector Machine (SVM) by executing many iterations, each of which removes one useless feature. Compared with those methods, our method can avoid many iterations. In addition, a hybrid genetic algorithm is proposed to increase the convergence speed and decrease the training time of RSC. The models generated by RSC take the form of "IF-THEN" rules, which have the advantage of explication. Tests and compa 相似文献
5.
Aimed at attaining to an integrated and effective pattern to guide the port design process, this paper pats forward a new conception of feature solution, which is based on the parameterized feature modeling. With this solution, the overall port pre-design process can be conducted in a virtual pattern. Moreover, to evaluate the advantages of the new design pattern, an application of port system has been involved in this paper; and in the process of application a computational fluid dynamic analysis is concerned. An ideal effect of cleanness, high efficiency and high precision has been achieved. 相似文献
6.
《天津大学学报(英文版)》2010,(2)
The cumulative sum (CUSUM) algorithm is proposed to detect the selfish behavior of a node in a wireless ad hoc network. By tracing the statistics characteristic of the backoff time between successful transmissions, a wireless node can distinguish if there is a selfish behavior in the wireless network. The detection efficiency is validated using a Qualnet simulator. An IEEE 802.11 wireless ad hoc network with 20 senders and 20 receivers spreading out randomly in a given area is evaluated. The well-behaved senders use minimum contention window size of 32 and maximum contention window size of 1 024, and the selfish nodes are assumed not to use the binary exponential strategy for which the contention window sizes are both fixed as 16. The transmission radius of all nodes is 250 m. Two scenarios are investigated: a single-hop network with nodes spreading out in 100 m×100 m, and all the nodes are in the range of each other; and a multi-hop network with nodes spreading out in 1 000 m×1 000 m . The node can monitor the backoff time from all the other nodes and run the detection algorithms over those samples. It is noted that the threshold can significantly affect the detection time and the detection accuracy. For a given threshold of 0.3 s, the false alarm rates and the missed alarm rates are less than 5%. The detection delay is less than 1.0 s. The simulation results show that the algorithm has short detection time and high detection accuracy. 相似文献
7.
Traffic monitoring is of major importance for enforcing traffic management policies. To accomplish this task, the detection of vehicle can be achieved by exploiting image analysis techniques. In this paper, a solution is presented to obtain various traffic parameters through vehicular video detection system( VVDS). VVDS exploits the algorithm based on virtual loops to detect moving vehicle in real time. This algorithm uses the background differencing method, and vehicles can be detected through luminance difference of pixels between background image and current image. Furthermore a novel technology named as spatio-temporal image sequences analysis is applied to background differencing to improve detection accuracy. Then a hardware implementation of a digital signal processing (DSP) based board is described in detail and the board can simultaneously process fourchannel video from different cameras. The benefit of usage of DSP is that images of a roadway can be processed at frame rate due to DSP‘s high performance. In the end, VVDS is tested on realworld scenes and experiment results show that the system is both fast and robust to the surveillance of transportation. 相似文献
8.
According to the structural characteristics of hazardous waste landfill,a new model based on the finite element method(FEM)is developed.The detection layer is considered as a sealed space and it is assumed that total current flows through the leak for the high resistivity of geomembrane liner.The leak current is regarded as a positive point current I and the other current source is-I.Electrical potential of an arbitrary point in detection layer satisfies Poisson equation. Experiments for detecting leaks in liner were carried out.Excellent agreement between experimental data and simulated model data validates the new model.Parametric curves for a single leak show that with optimum selection of field survey parameters leaks can be detected effectively.For multiple leaks,the simulated results indicate that they are detectable when leak separation is larger than measurement spacing. 相似文献
9.
For the typical color detects of polysilicon wafers, i.e., edge discoloration, color inaccuracy and color non-uniformity, a new integrated machine vision detection method is proposed based on an HSV color model. By transforming RGB image into three-channel HSV images, the HSV model can efficiently reduce the disturbances of complex wafer textures. A fuzzy color clustering method is used to detect edge discoloration by defining membership function for each channel image. The mean-value classi- fying method and region growing method are used to identify the other two defects, respectively. A vision detection system is developed and applied in the produc- tion of polysilicon wafers. 相似文献
10.
1IntroductionIntrusion detection systems(IDS)can be catego-rizedinto two types bytheir detection algorithms:mis-use detection and anomaly detection.Misuse detectiondefines known attack signatures(using expert know-ledge),and tries to find the ones that ma… 相似文献
11.
徐阳 《温州职业技术学院学报》2012,12(1):56-59
大部份TCP拥塞控制机制是依赖分组丢失来触发的,容易产生拥塞。为减少拥塞的产生,提出TCPMlc拥塞控制机制,即借助路由器辅助把网络内部信息传递给发送端,不需要依赖分组丢失,在发生拥塞前就可进行适度的传输控制,以减少因分组丢失而造成传输速度的剧烈下降,并可快速达到最佳传输速度。实验表明,该方法能有效避免拥塞的产生,降低丢包率,提高整体吞吐量。 相似文献
12.
为了降低TCP流的处理开销,可以从TCP/IP报文中选取某些位串来作为流的标识.从位熵和随机性的角度分析了TCP流首报文的顺序号(SN)和确认号(AN)的分布,提出了一种从重尾的IP或TCP流里获得随机均匀的流标识的新方法(FIDSAN).实验结果表明,在可以接受的冲突概率下,TCP流首报文的顺序号和确认号的部分高位比特可以用来作为流标签.给定冲突概率时,该流标识的比特长度可以根据一个由观察窗口和流ID值域导出的关系式求出.与TCP五元组,CRC,Checksum等比较发现,FIDSAN具有更低的计算开销. 相似文献
13.
传统有线网络TCP拥塞控制机制建立在拥塞是网络丢包原因的基础上,所以该机制不能适应无线网络中高误码率造成的无线链路丢包的情况.因此,我们提出一种基于移动算法的DSTCP解决方案,该机制和算法能有效地降低无线网络中的丢包率,提高信道的利用率和性能. 相似文献
14.
刘俊 《深圳信息职业技术学院学报》2014,(3):8-11
针对无线环境下FTCP性能恶化的问题,在研究分析一种自适应拥塞避免算法的基础上,提出一种基于该算法的无线TCP改进机制。该机制引入拥塞丢包与误码丢包的判决因子,能针对无线误码的判断采取更为准确的发送速率调整机制,很大程度上实现了拥塞控制与差错控制的分离,从而提升了无线TCP6的性能改善。仿真结果表明,基于自适应拥塞避免算法的TCP改进机制性能得到显著优化。 相似文献
15.
针对计算机网络规模大、网络流量大、结构复杂等特点,使得检测代理负载过大导致丢包率较高而准确率较低,提出了基于神经网络的协同入侵检测,该方法根据网络协议构建多个检测代理(TCP检测代理、UDP检测代理和ICMP检测代理),多个检测代理协同工作减少检测代理的负载,从而提高检测准确率。最后用KDDCUP99进行仿真实验,结果表明该方法可以有效提高训练时间和检测时间,同时提高准确率。 相似文献
16.
利用WinPcap提供的编程功能,设计了网络数据包捕获系统,实现了数据包的循环捕获以及对包内Ethernet、ARP、IP、TCP、UDP、ICMP等协议的分析.运行结果表明,该系统能够完成数据包的捕获和分析工作,提高网络的安全可靠性. 相似文献
17.
针对IPv6与IPv4协议不完全兼容,为了保证TCP包在IPv4／IPv6网络互通时的传输正确性,通过对TCP滑动窗口机制的分析,设计了一套新的会话控制列表结构来记录TCP包在进行转换时候序号发生的变化,并且在转换网关处理程序中加入对该表的控制,保证了转换中的数据包序号的正确性,同时也解决了重传包的检测和处理问题． 相似文献
18.
在移动Ad Hoc网络环境中，链路失效和路由改变的事件经常发生．TCP应用在这样的环境中性能是低下的，因为它总是认为数据包的丢失是由于网络拥塞造成的．提出一种改进的AODV路由协议（E-AODV），此协议在选路时会选择一条稳定的路径，进而提高TCP的吞吐量．仿真结果表明E-AODV协议是有效的． 相似文献
19.
於晓兰 《武汉职业技术学院学报》2009,8(5):54-56,59
在研究网络扫描技术的基础上,提出了基于TCP/IP的网络扫描策略,集成了多种高效的扫描方式,其中重点给出了基于套接字的半开放式扫描和ICMP网络主机扫描的实现过程。 相似文献
20.
INTRODUCTION The Transport Control Protocol (TCP) pro-vides end-to-end reliable connection-oriented ser-vice over heterogeneous networks. After the fa-mous 1986 network collapse due to network con-gestion, TCP congestion control mechanisms wereintroduced in TCP protocol. The congestion controlmechanisms in early TCP, known as TCP-Tahoe,are discussed in Congestion Avoidance and Control(Jacobson, 1988). Tahoe introduces two basicmechanisms: slow start and congestion avoidance… 相似文献