China Defense Science and Technology Information Center

Beijing, China

China Defense Science and Technology Information Center

Beijing, China

Time filter

Source Type

Xing B.,Academy of Armored force Engineering | Cao J.,Academy of Armored force Engineering | Song T.,China Defense Science and Technology Information Center | Chen S.,Academy of Armored force Engineering
Xitong Fangzhen Xuebao / Journal of System Simulation | Year: 2017

The agent based modeling and simulation method is an effective method in the field of complex systems and system of systems (SoS), which is deficient in the connection relationship between the agent and the complex network method. According to the actual situation of the army equipment support, a simulation model of the maintenance support system for the equipment support system of systems based on the ABMS and complex network was established, which mainly included the overhaul maintenance, the medium maintenance, the minor repair and the examined and repaired as the special equipment support activity processes. On the basis of the combination for the ABMS and complex network method, it is beneficial to grasp the operating rules of the equipment support and improve the equipment support capability. © 2017, The Editorial Board of Journal of System Simulation. All right reserved.


Hu X.,Chinese Academy of Sciences | Zhong H.,China Defense Science and Technology Information Center | Tang C.,Chinese Academy of Sciences
Advances in Space Research | Year: 2013

As important products of GNSS navigation message, ionospheric delay model parameters are broadcasted for single-frequency users to improve their positioning accuracy. GPS provides daily Klobuchar ionospheric model parameters based on geomagnetic reference frame, while the regional satellite navigation system of China's COMPASS broadcasts an eight-parameter ionospheric model, COMPASS Ionospheric Model(CIM), which was generated by processing data from continuous monitoring stations, with updating the parameters every 2 h. To evaluate its performance, CIM predictions are compared to ionospheric delay measurements, along with GPS positioning accuracy comparisons. Real observed data analysis indicates that CIM provides higher correction precision in middle-latitude regions, but relatively lower correction precision for low-latitude regions where the ionosphere has much higher variability. CIM errors for some users show a common bias for in-coming COMPASS signals from different satellites, and hence ionospheric model errors are somehow translated into the receivers' clock error estimation. In addition, the CIM from the China regional monitoring network are further evaluated for global ionospheric corrections. Results show that in the Northern Hemisphere areas including Asia, Europe and North America, the three-dimensional positioning accuracy using the CIM for ionospheric delay corrections is improved by 7.8%-35.3% when compared to GPS single-frequency positioning ionospheric delay corrections using the Klobuchar model. However, the positioning accuracy in the Southern Hemisphere is degraded due apparently to the lack of monitoring stations there.


Wang X.,Xi'an Jiaotong University | Wang C.,China Defense Science and Technology Information Center | Shen J.,Xi'an Jiaotong University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

Semi-supervised clustering uses a small amount of labeled data to aid and bias the clustering of unlabeled data. This paper explores the usage of labeled data to generate and optimize initial cluster centers for k-means algorithm. It proposes a max-distance search approach in order to find some optimal initial cluster centers from unlabeled data, especially when labeled data can't provide enough initial cluster centers. Experimental results demonstrate the advantages of this method over standard random selection and partial random selection, in which some initial cluster centers come from labeled data while the other come from unlabeled data by random selection. © 2011 Springer-Verlag.


Cai J.,Shijiazhuang Mechanical Engineering College | Shen X.,Shijiazhuang Mechanical Engineering College | Lei M.,China Defense Science and Technology Information Center | Lin C.,Shijiazhuang Mechanical Engineering College | Dou S.,Shijiazhuang Mechanical Engineering College
Optics Letters | Year: 2015

A novel asymmetric cryptosystem based on coherent superposition, which is free from silhouette problem, is proposed. Being different from the phase-truncated Fourier transform-based cryptosystem, the encryption process uses equal modulus decomposition (EMD) to create an effective trapdoor one-way function. As a result, the proposed method achieves high robustness against the special attack based on iterative Fourier transform. Simulation results are presented to prove the validity of the proposed system. © 2015 Optical Society of America.


Zhang Y.,Hospital of Beijing PAPF | Hu Z.J.,Hospital of Beijing PAPF | Niu H.B.,China Defense Science and Technology Information Center
Control Engineering and Information Systems - Proceedings of the International Conference on Control Engineering and Information System, ICCEIS 2014 | Year: 2015

With the growing scale of high performance computing platforms and the increasing scientific computing demands, fault tolerance in MPI programs has become a major issue. This paper proposed an analytical performance model to help checkpointing mechanisms to get better performance. In this paper, after the introduction of different fault tolerant mechanisms, we focus on the segment-level and variable-level checkpointing approaches and analyze how the fault tolerant mechanisms affect the performance of current MPI systems, then we introduced the analytical performance model we proposed. Last we evaluated and analyzed the performance of two classic fault tolerant approaches and propose what should be done to advance variable-level checkpointing mechanisms. © 2015 Taylor & Francis Group, London.


Ding W.,China Defense Science and Technology Information Center | Liu Y.,China Defense Science and Technology Information Center | Zhang J.,National University of Defense Technology
IC3K 2015 - Proceedings of the 7th International Joint Conference on Knowledge Discovery, Knowledge Engineering and Knowledge Management | Year: 2015

Cloud storage for information sharing is likely indispensable to the future national defence library in China e.g., for searching national defence patent documents, while security risks need to be maximally avoided using data encryption. Patent keywords are the high-level summary of the patent document, and it is significant in practice to efficiently extract and search the key words in the patent documents. Due to the particularity of Chinese keywords, most existing algorithms in English language environment become ineffective in Chinese scenarios. For extracting the keywords from patent documents, the manual keyword extraction is inappropriate when the amount of files is large. An improved method based on the term frequency-inverse document frequency (TF-IDF) is proposed to auto-extract the keywords in the patent literature. The extracted keyword sets also help to accelerate the keyword search by linking finite keywords with a large amount of documents. Fuzzy keyword search is introduced to further increase the search efficiency in the cloud computing scenarios compared to exact keyword search methods. Based on the Chinese Pinyin similarity, a Pinyin-Gram-based algorithm is proposed for fuzzy search in encrypted Chinese environment, and a keyword trapdoor search index structure based on the n-ary tree is designed. Both the search efficiency and accuracy of the proposed scheme are verified through computer experiments. © 2015 by SCITEPRESS - Science and Technology Publications, Lda.


Ding W.,China Defense Science and Technology Information Center | Liu Y.,China Defense Science and Technology Information Center | Zhang J.,National University of Defense Technology
IC3K 2015 - Proceedings of the 7th International Joint Conference on Knowledge Discovery, Knowledge Engineering and Knowledge Management | Year: 2015

The introduction of the ontology-driven mechanism brings new opportunities for the knowledge management. In this paper, we describe the results of our continuing work, by researching on the structure design of the ontology-driven knowledge management system, and propose three stages in the system model, i.e., the knowledge acquisition, the knowledge organization and knowledge application. Based on the proposed model, we choose the technology novelty consulting system in our patent library as the platform to perform the patent knowledge management and the experiment results validate the feasibility and validation of our system model. © 2015 by SCITEPRESS - Science and Technology Publications, Lda. All rights reserved.


Liu S.,Dalian Naval Academy | Shen T.,China Defense Science and Technology Information Center | Dai Y.,Dalian Naval Academy
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

In order to segment the target well and suppress background noises effectively, an infrared image segmentation method based on spatial coherence histogram and maximum entropy is proposed. First, spatial coherence histogram is presented by weighting the importance of the different position of these pixels with the same gray-level, which is obtained by computing their local density. Then, after enhancing the image by spatial coherence histogram, 1D maximum entropy method is used to segment the image. The novel method can not only get better segmentation results, but also have a faster computation time than traditional 2D histogram-based segmentation methods. © 2014 SPIE.


Shi G.,University of Science and Technology of China | Bao S.,University of Science and Technology of China | Lai W.,University of Science and Technology of China | Rao Z.,University of Science and Technology of China | And 2 more authors.
Scanning | Year: 2013

An electron beam inducing method for sprouting large quantities of silver nanoparticles on the surface of silver chloride particles is reported. The electron beam driven process was characterized by time-dependent scanning electron microscope (SEM) and energy dispersive spectrum (EDS), allowing for observing several key intermediates in and characteristics of the growth process. Theoretical calculation coupled with experimental observation demonstrated that the growth of silver nanoparticles was mostly related to the current density of electron beam. Decomposition of the silver chloride on the surface of sample was under electron beam irradiation resulted in silver nanoparticles and chlorine. This phenomenon could be useful in developing a novel mechanism for preparation of nanostructures and proposing a reference to avoid image distortion during the characterization of silver compounds under SEM. SCANNING 35: 69-74, 2013. © 2012 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.


Wang Y.,China Defense Science and Technology Information Center | Luo Z.,China Defense Science and Technology Information Center | Yu Y.,China Defense Science and Technology Information Center
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

Diversifying the results retieved is an effective approach to tackling users’ information needs in Twitter, which typically described by query phrase are often ambiguous and have more than one interpretation. Due to tweets being often very short and lacking in reliable grammatical sytle, it reduces the effectiveness of traditional IR and NLP techniques. However, Twitter, as a social media, also presents interesting opportunies for this task (for example the author information such as the number of statuses). In this paper, we firstly address diversitication of the search results in Twitter with a learning method and explore a series of diversity features describing the relationship between tweets which include tweet content, sub-topic of tweet and the Twitter specific social information such as hashtags. The experimental results on the Tweets2013 datasets demonstrate the effectiveness of the learning approach. Additionally, the Twitter retrieval task achieves improvement by taking into account the diversity features. Finally, we find the sub-topic and Twitter specific social features can help solve the diversity task, especially the post time, hashtags of tweet and the location of author. © Springer International Publishing Switzerland 2016.

Loading China Defense Science and Technology Information Center collaborators
Loading China Defense Science and Technology Information Center collaborators