Biblio

In electronic warfare, communication may not counter reconnaissance and jamming without the help of network-station selection of frequency hopping. The competition in the field of electromagnetic spectrum is becoming more and more fierce with the increasingly complex electromagnetic environment of modern battlefield. The research on detection, identification, parameter estimation and network station selection of frequency hopping communication network has aroused the interest of scholars both at home and abroad, which has been summarized in this paper. Firstly, the working mode and characteristics of two kinds of FH communication networking modes synchronous orthogonal network and asynchronous non orthogonal network are introduced. Then, through the analysis of FH signals time hopping, frequency hopping, bandwidth, frequency, direction of arrival, bad time-frequency analysis, clustering analysis and machine learning method, the feature-based method is adopted Parameter selection technology is used to sort FH network stations. Finally, the key and difficult points of current research on FH communication network separation technology and the research status of blind source separation technology are introduced in details in this paper.

A THz image edge detection approach based on wavelet and neural network is proposed in this paper. First, the source image is decomposed by wavelet, the edges in the low-frequency sub-image are detected using neural network method and the edges in the high-frequency sub-images are detected using wavelet transform method on the coarsest level of the wavelet decomposition, the two edge images are fused according to some fusion rules to obtain the edge image of this level, it then is projected to the next level. Afterwards the final edge image of L-1 level is got according to some fusion rule. This process is repeated until reaching the 0 level thus to get the final integrated and clear edge image. The experimental results show that our approach based on fusion technique is superior to Canny operator method and wavelet transform method alone.

Distributed Denial of Services (DDoS) attacks continue to be one of the most challenging threats to the Internet. The intensity and frequency of these attacks are increasing at an alarming rate. Numerous schemes have been proposed to mitigate the impact of DDoS attacks. This paper presents a comprehensive empirical evaluation of Machine Learning (ML)based DDoS detection techniques, to gain better understanding of their performance in different types of environments. To this end, a framework is developed, focusing on different attack scenarios, to investigate the performance of a class of ML-based techniques. The evaluation uses different performance metrics, including the impact of the “Class Imbalance Problem” on ML-based DDoS detection. The results of the comparative analysis show that no one technique outperforms all others in all test cases. Furthermore, the results underscore the need for a method oriented feature selection model to enhance the capabilities of ML-based detection techniques. Finally, the results show that the class imbalance problem significantly impacts performance, underscoring the need to address this problem in order to enhance ML-based DDoS detection capabilities.

Embodied conversational agents are changing the way humans interact with technology. In order to develop humanlike ECAs they need to be able to perform natural gestures that are used in day-to-day conversation. Gestures can give insight into an ECAs personality trait of extraversion, but what factors into it is still being explored. Our study focuses on two aspects of gesture: amplitude and frequency. Our goal is to find out whether agents should use specific gestures more frequently than others depending on the personality type they have been designed with. We also look to quantify gesture amplitude and compare it to a previous study on the perception of an agent's naturalness of its gestures. Our results showed some indication that introverts and extraverts judge the agent's naturalness similarly. The larger the amplitude our agent used, the more natural its gestures were perceived. The frequency of gestures between extraverts and introverts seem to contain hardly any difference, even in terms of types of gesture used.