最新成果rss-机构知识库http:www.notefist.com科研成功最新成果rssExperimental research of the gas-dynamic efficiency of the high pressure-differential HPT bladinghttp://ir.nwpu.edu.cn/AchivementDetails/Index/195793Zheng Guanghua,2019/12/17 8:42:04The results of the experimental investigation of gas-dynamic characteristics of two blade systems of high pressure-differential HPT with high reactivity are presented. The coefficients of the profile losses and secondary losses on the profile as a functioRussian Aeronautics201154143-48Russian Aeronautics,2011,54(1):43-48Robust adaptive control based on wavelet neural network for a hypersonic vehiclehttp://ir.nwpu.edu.cn/AchivementDetails/Index/220706Wang, Shou-Bin, Wang, Xin-Min, Yao, Cong-Chao, et al. 2019/9/30 15:40:11In order to enhance robustness of dynamic inversion controller for a general hypersonic vehicle, a stable robust adaptive control strategy based on wavelet neural network is proposed. An adaptive term implements by the wavelet neural network output to approximately cancel uncertainties, and also a robust term is designed to attenuate the approximation error with guaranteed performance and stability. The system asymptotically tracks the desired output by means of on-line studying uncertainties via wavelet neural network. Theoretical analysis is done to validate Lyapunov stability of the system. The simulation results show that the developed method can provide sufficient robustness and adaptability. This method is effective and deals with the problem of uncertain parameters preferably. ? 2011 IEEE.IEEE 2nd International Conference on Computing, Control and Industrial Engineering, CCIE 201120112332-336IEEE 2nd International Conference on Computing, Control and Industrial Engineering, CCIE 2011,2011,2:332-336Integrative tactical decision-making of information-based Cooperative Air Combat with ameliorative Lanchester equationshttp://ir.nwpu.edu.cn/AchivementDetails/Index/220723Wan, Kaifang, Gao, Xiaoguang,2019/9/30 15:40:11Present a characteristic of systematic rivalry, modern combat under conditions of information presents a low applicability of the traditional Lanchester theory. In the light of this, a reformative Lanchester attrition model of information-based Cooperative Air Combat considering the factors of both collaborative combat and electronic warfare is developed in this paper. On the basis of the definition of four dominant functions, a tactical decision-making model called 'the combination and classification of superiority interval' is proposed. The results of numerical examples indicate that the improved Lanchester model can simulate the process of modern air combat commendably and can make a great exaltation of Integrative operational efficiency combining with the tactical decision-making model. ? 2011 IEEE.2011 IEEE International Conference on Computer Science and Automation Engineering, CSAE 20112011128-322011 IEEE International Conference on Computer Science and Automation Engineering, CSAE 2011,2011,1:28-32Modeling of C3I communication network based on real-time queuing theoryhttp://ir.nwpu.edu.cn/AchivementDetails/Index/220724Liu, Yu, Wu, Yong, Zhang, Jiangdong,2019/9/30 15:40:11With a characteristic of low utilization of queue space and network resources, the C3I Communication Network model based on the traditional Queuing Theory gets a poor real-time capability of information transmitting. In the light of this, a new model based on the Real-time Queuing Theory is proposed for managing and scheduling the transmitting of information which reduces the messages occupying the queue resources without servicing on time and improves the network transmission efficiency. Then, a new index named message schedule service rate is presented to evaluate the performance of the network. Simulation results show that the C3I communication network model based on Real-time Queuing Theory obtained a higher average service rate and a better real-time capability which means the rationality of the model has been verified ? 2011 IEEE.2011 IEEE International Conference on Computer Science and Automation Engineering, CSAE 201120111109-1122011 IEEE International Conference on Computer Science and Automation Engineering, CSAE 2011,2011,1:109-112Evaluation on the efficiency of financial governance of listed companies under split share structure reformhttp://ir.nwpu.edu.cn/AchivementDetails/Index/220726Zheng, Shaofeng, Huang, Qinghua,2019/9/30 15:40:11The split share structure reform is a major institutional change of China's capital market, which has a long and great influence on China's capital markets and listed companies. In order to measure the impact of financial governance on share reform of listed companies, by the use of DEA, calculation and evaluation of the efficiency of financial governance, the paper clearly indicated the main factors that affect the financial governance: Institutional ownership, the largest shareholders, creditors, executive compensation, independent directors, which influence the efficiency of financial governance from the financial governance structure and mechanisms, therefore, they should be the starting point to improve financial governance efficiency. ? 2011 Springer-Verlag Berlin Heidelberg.2011 International Symposium on Applied Economics, Business and Development, ISAEBD 20112011210 CCISPART 3372-3772011 International Symposium on Applied Economics, Business and Development, ISAEBD 2011,2011,210 CCIS(PART 3):372-377A study on the net greenhouse gas emissions under intensive high-yielding cropland in North China-a case study of winter wheat-summer maize rotation system in Huantai Countyhttp://ir.nwpu.edu.cn/AchivementDetails/Index/220729Bai, Shaojun, Lian, Long, Ma, Xun,2019/9/30 15:40:11Utilizing the LCA matrix, we preliminarily analyzed whether wheat-maize rotation system was a carbon sink or a source based on long-term and large-scale straw return in Huantai county. The results indicated that the mode was a carbon source if we comprehensively considered agricultural materials production subsystem and farming subsystem together, with the quantity of net GHGs being -1075.71kgCO2e when producing 1 ton of wheat and maize. But if only farming system was considered, the averaged quantity of cropland carbon sequestration was +262.31 kgCO2e, which could offset the -222.99 kgCO2e carbon emission caused by fertilizes and agricultural machine. Therefore, through straw return and tillage system improvement, farming system might become the carbon sink in the future. ? 2011 Published by Elsevier Ltd.2010 International Conference on Energy, Environment and Development, ICEED 201020115785-7922010 International Conference on Energy, Environment and Development, ICEED 2010,2011,5:785-792The sustainable development evaluation of energy and chemical engineering base of Northern Shaanxi regionhttp://ir.nwpu.edu.cn/AchivementDetails/Index/220735Xie, Wei, Zhao, Songzheng, Li, Jianzhong,2019/9/30 15:40:11The purpose of this article is to provide a systematic evaluation method to the sustainable development of energy and chemical engineering base of Northern Shaanxi region. As one of the abundant region which has minerals such as coal, oil, gas and halite in China, the growth of energy and chemical engineering base of Northern Shaanxi region is crucial to the economy development and society stability of the northwest and even the nation. The author makes use of AHP and fuzzy comprehensive evaluation, takes Northern Shaanxi region as an example, builds evaluation model from five aspects which are economic, social, resources, environmental and intelligence, and conducts systemic evaluation. The conclusion demonstrates that the sustainable development level of the base of Northern Shaanxi region has greatly improved in nearly five years, but still needs further efforts. ? 2011 IEEE.2nd International Conference on E-Business and E-Government, ICEE 201120112835-28392nd International Conference on E-Business and E-Government, ICEE 2011,2011,2835-2839An automatic surface extraction for volume visualizationhttp://ir.nwpu.edu.cn/AchivementDetails/Index/220753Ma, Yu, Zhang, Yanning, Wang, Xiyuan, et al. 2019/9/30 15:40:11This paper describes a novel automatic 3D surface extraction method for biomedical volume images. In this technique, the region of interesting (ROI) in 2D slice images is selected interactively, 3D ROI edge surface is determined by using Laplace operator based tracking method. According to coplanar principle of the voxel, the edge surface in ROI is then automatically extracted by region growing approach. Finally, the 3D edge surface of high accuracy (sub-voxel) is formed by reconstruction of the edge surface selected in 2D ROI. Experiments on biomedical images show that the new method is successful in interactive selection and automatic extraction of edge surfaces in 3D images.3rd International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 201120111387-3903rd International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2011,2011,1:387-390The effect of campus network culture on ideological and political educationhttp://ir.nwpu.edu.cn/AchivementDetails/Index/220767Wu, Yuncai,2019/9/30 15:40:1121st century is a networked and digitized high-technology age ,the information revolution cored by Network has entered university campus ,whose popularization and widely-use has broaden the horizon of the students and brought convenience to their daily life and study. In spite of that, its harmful aspects have hugely influenced the students on their thought, values and behaviors which add much more difficulty to the ideological and political education. ?2010 IEEE.2010 3rd International Conference on Artificial Intelligence and Education, ICAIE 20102010687-6902010 3rd International Conference on Artificial Intelligence and Education, ICAIE 2010,2010,687-690The influence of dielectric constant on bandwidth of U-notch microstrip patch antennahttp://ir.nwpu.edu.cn/AchivementDetails/Index/220770Zhang, Linxi, Zhang, Qi, Hu, Chufeng,2019/9/30 15:40:11A rectangle patch antenna with U-notch is a practical method to improve the bandwidth of microstrip antennas bandwidth. If special material substrate and add matching network are combined, which not only reduce the quality factor of antenna, but also produce maximum output power for little reflection of load. When the dielectric constant �� of special material substrate changes, the bandwidth of U-notch microstrip patch antennas is different. The impact of dielectric constant is discussed in detail. The S11 parameter of the antenna has been simulated by HFSS. The simulation results show that the lower dielectric constant can gain wider band of antenna. ? 2010 IEEE.2010 IEEE International Conference on Ultra-Wideband, ICUWB201020101135-1382010 IEEE International Conference on Ultra-Wideband, ICUWB2010,2010,1:135-138Reliability analysis of two kinds take-back models in reverse logisticshttp://ir.nwpu.edu.cn/AchivementDetails/Index/220771Zhang, Jing, Liang, Gongqian, Li, Hui,2019/9/30 15:40:11The complexity and high uncertainty of reverse logistics have brought great difficulties to the reasonable operation and decision-makings of each supply chain node. Under the profits and costs analysis in the research of reverse logistics structure, there have been contradictions in the choice of sales take-back models. Through discussion of the after recall process - the nodes of processing plants, remanufacturers and renewable suppliers, and the path reliability between them, structure reliability of two take-back models have been analyzed. In different time of reverse logistics life cycle, there are different choices in decision making. ? 2010 ASCE.2010 International Conference of Logistics Engineering and Management: Logistics for Sustained Economic Development - Infrastructure, Information, Integration, ICLEM 20102010387758-7642010 International Conference of Logistics Engineering and Management: Logistics for Sustained Economic Development - Infrastructure, Information, Integration, ICLEM 2010,2010,387:758-764A learning algorithm for one-class data stream classification based on ensemble classifierhttp://ir.nwpu.edu.cn/AchivementDetails/Index/220778Zhang, Dong, Wang, Yong, Cai, Lijun, et al. 2019/9/30 15:40:11Current research on data stream classification mainly focuses on supervised learning, in which a fully labeled data stream is needed for training. However, fully labeled data streams are expensive to obtain, which makes the supervised learning approach difficult to be applied to real-life applications. In this paper, we consider the problem of one-class classification on data stream with respect to concept drift where a large volume of data arrives at a high speed and with change of concept. In this case, only a small number of positively labeled examples is available for training. We propose our OcEC(One-class Ensemble Classifiers)algorithm and have it compared with WEC[1] algorithm and SEA[2] algorithm. Experimental study on both Moving Hyperplane dataset and SEA dataset shows that the OcEC algorithm has excellent classification performance and can quickly adapt to concept drift. ? 2010 IEEE.2010 International Conference on Computer Application and System Modeling, ICCASM 201020102V2596-V26002010 International Conference on Computer Application and System Modeling, ICCASM 2010,2010,2:V2596-V2600Classifying skewed data streams based on reusing datahttp://ir.nwpu.edu.cn/AchivementDetails/Index/220780Liu, Peng, Cai, Lijun, Wang, Yong, et al. 2019/9/30 15:40:11Current research community on data streams mining focuses on mining balanced data streams. However, the skewed class distribution appears in many data streams applications. In this paper, we introduce the method of discovering concept drifting on skewed data streams and propose an algorithm for c1assitying skewed data streams based on reusing data, RDFCSDS (Reuse Data for Classitying Skewed Data Streams). We evaluate RDFCSDS algorithm on Moving Hyperplane data set. The experiment results show that the sampling method based on reusing data works better than the simple sampling method and cluster sampling method on skewed data streams with concept drifting.2010 International Conference on Computer Application and System Modeling, ICCASM 201020104V490-V4932010 International Conference on Computer Application and System Modeling, ICCASM 2010,2010,4:V490-V493Application of particle swarm optimization for the design of a broadband microstrip antennahttp://ir.nwpu.edu.cn/AchivementDetails/Index/220781Zhao, Ya-Min, Xu, Jia-Dong,2019/9/30 15:40:11The discrete binary particle swarm optimization (PSO) is an extension of standard PSO on binary system. As a time-domain method, finite different time domain (FDTD) can obtain the required broadband frequency information through once time-domain calculation. Therefore, PSO's fitness function can choose multi-point in frequency, that is, the design of fitness function is more flexible when PSO is combining with FDTD. In this paper, discrete binary PSO combined with FDTD method is applied to design a broadband microstrip antenna. Test results show the bandwidth of the optimized antenna at -10dB is expanded significantly compared with the original antenna. ? 2010 IEEE.2010 International Conference on Computer Application and System Modeling, ICCASM 2010201015v15406-v154082010 International Conference on Computer Application and System Modeling, ICCASM 2010,2010,15:v15406-v15408A ciphertext retrieval model for encrypted XML database with bucket management algorithmhttp://ir.nwpu.edu.cn/AchivementDetails/Index/220785Lu, Xuan-Min, You, Jun, Zhou, Ya-Jian,2019/9/30 15:40:11To resolve the problems of security and ciphertext query efficiency for the XML database, a ciphertext retrieval model is presented in this paper. In this model, the value index and structure index in the encrypted XML database are established and the entrance addresses are recorded with the bucket management algorithm to realize the rapid retrieval for encrypted XML data. Experiments results show that this model not only has high security and improved ciphertext retrieval efficiency, but also supports the range query and easy to update. ? 2010 IEEE.2010 International Conference on Management and Service Science, MASS 201020102010 International Conference on Management and Service Science, MASS 2010,2010The relationship research between governance structure and company performance of energy listed companyhttp://ir.nwpu.edu.cn/AchivementDetails/Index/220800Chai, Huaqi, Song, Deqiang,2019/9/30 15:40:11Corporate governance structure is the most important structure in a modern enterprise system, whether reasonable or not is the most important decision factor for the business performance improving. By utilizing the sample data from 100 energy listed companies in Chinese stock market in 2008, combined with the particularity of the energy companies, using SPSS17.0 the relationship between governance structure and company performance of Chinese energy listed companies were studied. It's concluded that the relationship between governance structure and company performance of Chinese energy listed companies was not significant, and discuss its causes and countermeasures. ? 2010 IEEE.3rd International Conference on Information Management, Innovation Management and Industrial Engineering, ICIII 201020104168-1713rd International Conference on Information Management, Innovation Management and Industrial Engineering, ICIII 2010,2010,4:168-171RW-MAC: An asynchronous receiver-initiated ultra lowpower MAC protocol for wireless sensor networkshttp://ir.nwpu.edu.cn/AchivementDetails/Index/220801Yang, Dongyu, Qiu, Ying, Li, Shining, et al. 2019/9/30 15:40:11In this paper, we present an asynchronous energy-efficient MAC protocol called RW-MAC for wireless sensor networks. RW-MAC is a receiver-initiated MAC which significantly reduces energy consumption by precisely predicting the receiver's wakeup time while still achieves high concurrent performance. To minimize collision, we present an algorithm to stagger the wakeup time of each node in the same collision domain. RW-MAC also tries to optimize the send sequence to maximize the throughput. We have implemented RW-MAC on TinyOS and evaluated its performance on testbeds. The result shows RW-MAC achieves higher concurrent performance and lower energy consumption compared to RI-MAC and X-MAC.IET International Conference on Wireless Sensor Network 2010, IET-WSN 201020102010575 CP393-398IET International Conference on Wireless Sensor Network 2010, IET-WSN 2010,2010,2010(575 CP):393-398H�� state feedback control for UAV maneuver trajectory trackinghttp://ir.nwpu.edu.cn/AchivementDetails/Index/220806Jiao, Yusong, Du, Juan, Wang, Xinmin, et al. 2019/11/29 15:40:44In this paper a trajectory tracking system for UAV is studied. The system consists of a flight control system and a guidance law. In inner loop, robust H�� control theory is used to design the flight control system. In outer loop, the navigation control commands are produced by the deviation of the real position data of UAV and the preset flight path. The attitude commands are calculated from navigation control commands and are fed into the inner loop as input signals. Simulation results are presented to illustrate the performance of the trajectory tracking control system. The results show the effectiveness and practicability of the control method. ? 2010 IEEE.2010 International Conference on Intelligent Control and Information Processing, ICICIP 20102010PART 1253-2572010 International Conference on Intelligent Control and Information Processing, ICICIP 2010,2010,PART 1,253-257A parallel algorithm for constrained and nonlinear optimization problemshttp://ir.nwpu.edu.cn/AchivementDetails/Index/221170Wang, Bao, Qin, Sun,2019/11/29 15:41:45To improve Parallel Variable Transformation method (PVT) for unconstrained optimization problem, different research direction is constructed in every processor. The every research direction is proved to a descent direction. Every minimizer is researched along every descent direction in every processor. A starting vector is updated by selecting the minimizer in every processor in next iteration. In theory, Convergence and rates of convergence of the method is proved. Some numerical results on HP rx 2600 cluster show that experimental results are consistent with the theory, and the efficiency of the algorithm is very high. ?2010 IEEE.Proceedings - 2010 IEEE International Conference on Intelligent Computing and Intelligent Systems, ICIS 201020101666-669Proceedings - 2010 IEEE International Conference on Intelligent Computing and Intelligent Systems, ICIS 2010,2010,1:666-669Analytical energy model of coding-based reprogramming protocols in wireless sensor networkshttp://ir.nwpu.edu.cn/AchivementDetails/Index/346777Zhang, Yan, Zhang, Yu, Li, Jun-Wei, et al. 2019/10/1 15:39:54As application requirements evolve, the software on sensor nodes needs to be updated, or patched to fix errors to all the nodes of the entire networks. Recently, coding-based reprogramming protocols are proposed to provide efficient code dissemination in environments with high packet loss rate. Methods in analyzing the performance of these protocols, however, need further study. This paper presents an analytical model for energy cost based on time of dissemination and network topology. In this model, page pipelining and communication range between nodes are taken into accounts. Results from extensive simulations of a representative coding-based reprogramming protocol called Rateless Deluge coincide with the performance predicted by this model (the average relative error of single-node energy consumption is about 0.23%), thus validating the approach. These analytical results show that network density, network size and the number of packets per page all have significant impact on energy cost of the whole network. Particularly, a decrease in density of the network harms the energy performance (the energy consumption and network density is synthesized to be quadratic function). The energy cost of reprogramming the network is linear with the size of network (for the N��N grid network, the average growth rate is 50% when n change from 3 to 10) while the energy consumption of single node increases (the average growth rate is 6.9%). The energy cost is inverse with the page size of code image (the average rate of reduce is 11.2%). ? 2013 ISCAS.Ruan Jian Xue Bao/Journal of Software201324SUPPL.1125-133Ruan Jian Xue Bao/Journal of Software,2013,24(SUPPL.1):125-133一种基于CPS-ADL模型向混合程序转换的CPS建模与验证方法http://ir.nwpu.edu.cn/AchivementDetails/Index/542633周兴社, 拓明福, 张凡, 等. 2019/12/2 1:59:52本发明公开了一种基于CPS-ADL模型向混合程序转换的CPS建模与验证方法,主要用于处理CPS建模与属性验证问题,其特征在于:在CPS-ADL平台上采用扩展的混成系统描述语言E-HYSDEL对CPS进行建模;给出HP模型的形式化定义HPM,并在满足模型转换一致性的前提下建立CPS-ADL模型元素与HP模型元素之间的转换规则;基于这些转换规则,将具体CPS的模型描述代码自动转换为混合程序;按照定理证明器KeYmaera的输入格式,由混合程序和以动态微分逻辑描述的系统属性公式生成KeYmaera的输入文件;在KeYmaera中打开输入文件,进行推理验证。本发明细化了基于CPS-ADL模型向HP转换...20142014Experimental rocket motor applied in evaluate the ablation performance of ablation resistance materialshttp://ir.nwpu.edu.cn/AchivementDetails/Index/766051Wei, Xiang-Geng, He, Guo-Qiang, Li, Jiang, et al. 2019/11/28 15:51:00In order to evaluate the ablative performance of ablation resistance material and to validate the effect of cooling structure exactly, the experimental system based on rocket motor is developed, then the experimental researches on how the ablative performance of the C/SiC ceramic matrix composite material and penetration C/C composite material is influenced by ablation temperature, particle, ablation time, and the cooling effect of the composite cooling structure with C/SiC ceramic matrix composite material are done. It is indicated that experimental rocket motor can be widely used to examine the ablative performance of related materials, so as to provide strong research basis for ablation resistance materials. ? 2008 by the American Institute of Aeronautics and Astronautics, Inc.44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit200844th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit,2008The analysis on the rising section of experimental pressure in variable thrust pintle solid rocket motorhttp://ir.nwpu.edu.cn/AchivementDetails/Index/766054Wei, Xiang-Geng, He, Guo-Qiang, Li, Jiang, et al. 2019/11/28 15:51:00The experimental system of non-coaxial pintle solid rocket motor was designed, and through this system, the experiments that validate variable thrust principle were carried out. A series of experiments were done, so as to find out how motor free volume, pintle movement state, cylinder sending pintle to some position by one time or not, equivalent throat structure, and propellant influence the response of pressure during the change of thrust. And by analyzing the results, it is concluded that the response time of propellant is the primary factor which effects the response of pressure. ? 2008 by the American Institute of Aeronautics and Astronautics, Inc.44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit200844th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit,2008Partially linear mixed-effects joint models for skewed and missing longitudinal competing risks outcomeshttp://ir.nwpu.edu.cn/AchivementDetails/Index/1027653Lu Tao, Lu Minggen, Wang Min, et al. 2020/2/17 11:11:50Longitudinal competing risks data frequently arise in clinical studies. Skewness and missingness are commonly observed for these data in practice. However, most joint models do not account for these data features. In this article, we propose partially linear mixed-effects joint models to analyze skew longitudinal competing risks data with missingness. In particular, to account for skewness, we replace the commonly assumed symmetric distributions by asymmetric distribution for model errors. To deal with missingness, we employ an informative missing data model. The joint models that couple the partially linear mixed-effects model for the longitudinal process, the cause-specific proportional hazard model for competing risks process and missing data process are developed. To estimate the parameters in the joint models, we propose a fully Bayesian approach based on the joint likelihood. To illustrate the proposed model and method, we implement them to an AIDS clinical study. Some interesting findings are reported. We also conduct simulation studies to validate the proposed method.Journal of biopharmaceutical statistics2019296971-989Journal of biopharmaceutical statistics,2019,29(6):971-989一种基于改进warping变换的宽带目标检测方法http://ir.nwpu.edu.cn/AchivementDetails/Index/1027853姚远, 孙超, 刘雄厚, et al. 2019/11/6 15:39:03结合波导声传播规律进行水声信号处理是目前研究的热点,warping变换就是其中之一.warping变换是基于波导简正波频散特征的信号处理方法.它将浅海波导中的混叠信号变换为多个具有特定频率的单频分量(每个分量对应某一号特定的简正波),借助常规带通滤波器实现简正波分离,从而有效降低水声信号处理和分析难度.现有的使用warping变换对宽带目标进行检测的方法中,warping算子是在理想波导条件(压力释放海面和绝对硬海底)下推导得到的.中国声学学会2017年全国声学学术会议2017Vol.36299-300中国声学学会2017年全国声学学术会议,2017,Vol.36:299-300中型客车车内声场预测与控制http://ir.nwpu.edu.cn/AchivementDetails/Index/1027854雷烨, 曾向阳, 杜博凯, et al. 2019/11/6 15:39:03利用AutoSEA2软件建立了客车声振环境预测的简化模型,开展了车内声场预测,并与实验结果进行对比,验证了模型的可利用性。通过仿真分析,得到了有效的减振降噪方案,建议车身蒙皮喷涂沥青型阻尼材料并敷设4cm厚的塑料泡沫。最终为工程师们如何改善车内NVH性能提供指导。中国声学学会2017年全国声学学术会议2017Vol.36587-588中国声学学会2017年全国声学学术会议,2017,Vol.36:587-588缝翼位置对翼型气动性能与噪声特性的影响http://ir.nwpu.edu.cn/AchivementDetails/Index/1027855王红建, 张锐, 罗望,2019/11/6 15:39:03本文主要针对缝翼位置参数(缝道宽度、层叠长度和缝翼偏角)的改变来研究该类参数对翼型的气动特性和缝翼噪声的影响规律。研究得出在缝道宽度或层叠长度单独增大时,翼型气动性能下降,噪声增大,最大变化量分别为0.23和12.6dB;在缝翼偏转角为2°时,在Cl增大0.01情况下,缝翼远场噪声OASLPA下降了2.15dB,减噪效果显著;优化缝翼位置参数是提高翼型气动性能,控制缝翼噪声的一种有效途径。中国声学学会2017年全国声学学术会议2017Vol.36681-682中国声学学会2017年全国声学学术会议,2017,Vol.36:681-682基于CEEMDAN的水声信号降噪方法http://ir.nwpu.edu.cn/AchivementDetails/Index/1027856周士贞, 曾向阳,2019/11/6 15:39:02水下目标识别是水声领域的关键技术,而声信号在海水中传播时,由于受到其他目标以及复杂多变的海洋环境和仪器的影响,接收系统采集到的往往是信噪比非常低的非平稳信号.如果能有效降低噪声的影响,便有望提高水下目标识别系统的准确度和稳定性.本文提出了一种基于互补自适应噪声集总经验模态分解(CEEMDAN)的水声信号降噪方法,实验证明该方法能够有效提高输入信号信噪比。此外,在面对其他色噪声环境时,可根据相关先验信息,通过噪声能量对某一模态的阈值进行修正,提高降噪效果。中国声学学会2017年全国声学学术会议2017Vol.36263-264中国声学学会2017年全国声学学术会议,2017,Vol.36:263-264主动声呐距离维波束形成http://ir.nwpu.edu.cn/AchivementDetails/Index/1027857刘雄厚, 孙超, 杨益新, et al. 2019/11/6 15:39:02波束形成是声呐信号处理的重要方式之一.传统波束形成使用多个换能器在空间按照一定几何结构排列,获得期望的空间指向性和噪声抑制能力.迄今为止,所研究的声呐波束形成器都是在角度维进行滤波处理,即通过对阵列(对应多个空间采样点)信号进行延迟求和,使得某感兴趣角度上的信号通过,同时抑制其它方向的干扰并压低噪声.但是,当干扰和目标位于同一角度上时,仅使用传统的波束形成器无法对干扰进行有效滤除.利用从目标回波中提取一组多频分量,提出了距离维波束形成方法。所提方法将波束形成从角度维扩展到了距离维,获得了距离维扫描处理能力,可有效提高主动声呐在距离维的干扰抑制能力。中国声学学会2017年全国声学学术会议2017Vol.36369-370中国声学学会2017年全国声学学术会议,2017,Vol.36:369-370利用频响函数相关性分析的动力学边界识别方法http://ir.nwpu.edu.cn/AchivementDetails/Index/1040810刘伟, 杨智春, 王乐, et al. 2019/11/6 15:39:03针对结构动力学边界参数识别问题,提出了一种利用频响函数相关性分析的识别方法.通过推导频响函数相关系数与边界参数之间的关系,构建了相关系数关于边界参数的灵敏度方程,进而采用正则化方法建立了边界参数识别的迭代公式.最后,通过仿真算例验证了方法的有效性和可行性,结果表明:该方法能够有效识别结构的边界参数,识别后频响函数的相关系数明显提高,尤其是在共振与反共振区域.第十二届全国振动理论及应用学术会议20171-9第十二届全国振动理论及应用学术会议,2017,1-9考虑温度效应的薄板结构动力学拓扑优化http://ir.nwpu.edu.cn/AchivementDetails/Index/1040811徐斌, 李文玉, 赵磊,2019/11/6 15:39:03本文以经受温度载荷与简谐载荷的复合材料板为研究对象,提出了一种新的基于动柔顺度的多相材料热结构两尺度并行优化设计方法.分别以宏观结构和微观材料相体积为约束,结构动柔顺度为优化目标建立两尺度并行优化模型.基于BESO方法和SIMP插值模型,建立两尺度宏观结构和微观材料并行优化算法并进行灵敏度分析.通过均匀化方法,复合材料性能可以使用由结构离散的周期性代表单元来求解.数值算例表明本文所提的方法能够有效地求解热力耦合结构的多尺度并行优化设计问题.第十二届全国振动理论及应用学术会议20171-8第十二届全国振动理论及应用学术会议,2017,1-8Lamb波混叠波处理方法及在损伤识别中的应用http://ir.nwpu.edu.cn/AchivementDetails/Index/1040812潘家楠, 秦卫阳, 尚世杰,2019/11/6 15:39:03基于主动Lamb波的结构健康监测的关键在确定损伤的位置、程度以及类型.然而,即便是单一模式的直达波,边界反射波与损伤反射波也会发生混叠.混叠波是获得损伤信息的一个主要障碍.针对混叠的Lamb波,通常所采用的基准信号代数相减法容易受到结构自身及环境因素的干扰,产生较大的误差.本文基于回声隐藏以及语音识别处理方法,提出一种新的混叠波处理方法.首先通过系数比例自适应算法(Proportional Normalized Least Mean Square,PNLMS)计算得到混叠波形成路径的冲激响应,然后应用动态时间规整算法(Dynamic Time Warping,DTW)进行相似性检验筛选得到最佳的时延值,最后对损伤进行定位.为了验证方法,对于一块带损伤的铝板进行了验证实验,结果证明该方法且能够从混叠波中准确地提取损伤信息.第十二届全国振动理论及应用学术会议20171-10第十二届全国振动理论及应用学术会议,2017,1-10空间输液管道系统支承动力优化设计http://ir.nwpu.edu.cn/AchivementDetails/Index/1040813李正浩, 王栋,2019/11/6 15:39:03研究在液固耦合效应作用下,空间输液管道系统支承位置的优化设计.应用有限元数值分析,建立输液管道系统的振动方程.通过移动现有的支承位置,可有效提高输液管道系统的固有振动频率,抑制由于液固耦合效应而引发的管道结构振动及噪声水平.本文将空间管道结构的支承等效为二个方向相互关联的约束线弹簧,可分别定义各方向的约束刚度.以管道系统的基频最大化为优化目标,通过计算管道中可移动支承位置的灵敏度,实现对管道系统支承位置的优化设计.典型算例的优化结果表明,输液管道支承位置的优化设计将显著改善系统的振动特性.第十二届全国振动理论及应用学术会议20171-5第十二届全国振动理论及应用学术会议,2017,1-5含内部裂纹的空心轴转子系统动力学分析http://ir.nwpu.edu.cn/AchivementDetails/Index/1040814王彦霖, 杨永锋, 冯海波,2019/11/6 15:39:03对含有内部裂纹的空心轴转子系统进行动力学建模,研究内部裂纹对转子系统的动力学行为的影响规律.基于空心轴Timoshenko梁-轴模型和中性轴理论,建立以截面惯性矩为变量的裂纹单元刚度矩阵,采用转子动力学有限元方法建立裂纹转子系统的动力学方程.使用谐波平衡法求解动力学方程得到各点的稳态响应,表明裂纹的出现不仅降低了转子系统的临界转速,还使转子在临界转速和亚临界转速附近均出现振动的峰值;分析了裂纹的深度、裂纹的位置对转子系统的影响,表明裂纹位于转轴中部时对转子系统的影响较大,而且随着裂纹的扩展,振动峰值会增大,同时在亚临界转速附近转子系统会发生超谐波共振.研究结论可以为空心轴裂纹的检测和识别提供一定的指导.第十二届全国振动理论及应用学术会议20171-8第十二届全国振动理论及应用学术会议,2017,1-8铝合金振动疲劳红外监测技术研究http://ir.nwpu.edu.cn/AchivementDetails/Index/1040815吕胜利, 李斌, 马君峰,2019/11/6 15:39:03由于材料中不可避免地存在各种各样的微缺陷,包括点缺陷(空洞、夹杂物)、线缺陷(位错)及面缺陷(晶界、堆垛层错).各种晶体缺陷又都有一定的能量,尤其对于位错,其能量很大,所以在疲劳过程中,当外界对物体做功时,由于这些微缺陷不断的演化,各形变区的内能和动能将发生相应的改变,使一部分能量以热、声发射等形式耗散掉,同时在材料中产生温度场和熵增.本文提出通过分析铝合金振动疲劳过程中的热耗散来进行振动疲劳红外监测技术,并对不同加速度下的铝合金振动疲劳试样的热耗值进行分析计算,得到了有益于工程的结论.第十二届全国振动理论及应用学术会议20171-5第十二届全国振动理论及应用学术会议,2017,1-5连接界面微滑行为对叶肩阻尼器力传递特性的影响http://ir.nwpu.edu.cn/AchivementDetails/Index/1040816李东武, 徐超, 刘通,2019/11/6 15:39:03涡轮发动机工作时,由于受到高速气流周期性的作用,叶片会发生强烈振动,这些振动给发动机的正常使用引入了安全隐患.为了减少叶片因局部高幅振动造成的事故,提高其使用寿命,工程中常采用干摩擦阻尼器来耗散叶片间的振动能量,以达到减振的效果.本文将考虑法向载荷变化的微滑摩擦接触模型应用于涡轮发动机叶肩凸缘阻尼器振动系统的动力学分析,建立了相应的数学模型;采用数值积分方法求解了两种振动模态下振动系统的稳态响应,分析了各接触对的力学行为;并将微滑模型与宏滑模型在不同量级激励下的结果进行了对比.结果显示,数值仿真结果与实验结果能够很好地吻合;考虑界面微滑行为与否对叶片阻尼器力传递特性有重要影响.第十二届全国振动理论及应用学术会议20171-9第十二届全国振动理论及应用学术会议,2017,1-9基于气动肌腱的悬臂结构振动主动控制研究http://ir.nwpu.edu.cn/AchivementDetails/Index/1040817高鹏, 李斌, 邹成哲,2019/11/6 15:39:03大型柔性可展开结构是未来变体自适应结构和空间大型结构的热点研究方向之一,近年来在航空航天领域,民用和机械工程领域得到广泛研究.可展开结构由于追求初始阶段的可折叠存储包裹性,因此在展开驱动设计及展开后的结构振动控制等方面提出一些特殊的要求.传统刚性作动器很难适用于需要折叠的可展开结构,本文探索应用具备柔性可折叠特征的新型气动肌腱来进行这类结构的振动主动控制.本文以一己展开的悬臂结构为参考,设计制作了一个等效的两基板悬臂模型作为控制对象,运用经典动力学理论,建立悬臂板降阶数学模型.并将气动肌腱动力学模型与该降阶结构模型相耦合,基于正位置反馈(positive position feedback,以下简称PPF)控制算法,开展了主动控制系统的仿真研究.在控制仿真模型的基础上,本文基于半实物实时仿真系统dSPACE,搭建了振动主动控制实验平台,应用2根FESTO气动肌腱作为作动器开展了悬臂板的振动控制实验研究.实验结果表明基于气动肌腱的主动控制系统对悬臂结构的低频段振动具有良好的控制效果,验证本文建模分析方法及振动主动控制方法的有效性.第十二届全国振动理论及应用学术会议20171-9第十二届全国振动理论及应用学术会议,2017,1-9基于经验模态分解和独立成分分析的液体火箭发动机故障分析与诊断http://ir.nwpu.edu.cn/AchivementDetails/Index/1040818马引刚, 任兴民, 王元生,2019/11/6 15:39:03本文采用现代信号处理领域中的经验模态分解和独立成分分析对火箭发动机多模式组合故障下产生的复杂机械振动信号进行分离.先利用经验模态分解方法将一维测量信号分解为具有不同尺度特征的本征模态函数以实现对观测信号的升维,再结合独立成分分析对各个振源信号的独立响应进行分离,以获得源信号的相关先验信息,为进一步研究其结构振动传递特性奠定基础.研究结论对火箭发动机由于振动信号耦合而导致的振源不明、传递关系不清问题的分析具有理论意义和实际意义.第十二届全国振动理论及应用学术会议20171-7第十二届全国振动理论及应用学术会议,2017,1-7热环境下的壁板振动特性研究http://ir.nwpu.edu.cn/AchivementDetails/Index/1040819程响, 徐敏, 谢丹, et al. 2019/11/6 15:39:03随着飞行速度的提高,飞行器在飞行过程中将经历严酷的热环境。热环境下,飞行器结构的固有振动特性会发生变化,结构的稳定性会因此受到影响。本文对不同温度下底端固支的壁板进行振动特性分析.基于热模态理论,采用NASTRAN建立有限元分析模型,分别研究了均匀温度场、非均匀温度场两种情况对壁板振动模态的影响.结果表明,热环境下,弹性模量的降低使壁板的固有频率减小,热应力的产生对壁板固有频率和固有振型均有不同程度的影响.在两种不同温度场下,壁板固有频率变化趋势基本相同,固有振型变化存在差别.第十二届全国振动理论及应用学术会议20171-5第十二届全国振动理论及应用学术会议,2017,1-5基于Gibbs抽样与K-out-of-N系统的可靠性分析http://ir.nwpu.edu.cn/AchivementDetails/Index/1040820卢娜, 任兴民, 刘骁骁, et al. 2019/11/6 15:39:03本文以1994年北岭地震加州桥梁结构为研究对象,采用加州桥梁经验损伤数据作为地震响应,基于Gibbs抽样的MCMC算法,分别识别出不考虑统计相关性的模型参数及考虑统计相关性的模型参数,获得预测易损性曲线.假设桥梁系统为K-out-of-N系统,讨论了统计相关性对系统易损性的影响.第十二届全国振动理论及应用学术会议20171-8第十二届全国振动理论及应用学术会议,2017,1-8基于Cricket技术的航天器舱内超声波定位方案http://ir.nwpu.edu.cn/AchivementDetails/Index/1042612辛弄潮, 李伟,2019/11/6 15:39:02  针对航天器内部多障碍物阻隔,复杂无线电干扰的定位环境,以及精确定位的需求,以Cricket技术为基础设计一套结构简洁、测量精度高、信息保密性好、以及抗干扰力强的超声波定位方案。本定位方案在航天器内部放置空间位置已知的参考点与空间位置未知的待定点构成参考平面,在参考平面的基础上建立相应的三维空间坐标系,驱动参考点同时向待定点发出红外和超声波定位信号,采取时间差(TDOA)算法测量待定点与参考点的相对距离,在获取足够多的相对距离后结合已知参考点的位置信息来计算确定待定点的空间位置,最后利用组合算法处理数据从而克服由于外界干扰而引起的数据突变并减小数据扰动,进一步提高定位精度。理论上,利用三个参考点就可以获得待定点的空间位置,并且定位精度会随着参考点布局的密度增加以及参考平面的分层布局合理化而提高。通过气浮卫星实验平台在地面模拟航天器内部定位环境,并对方案进行实验验证。实验验证结果表明本方案定位精度为5cm,适合开展航天器内部的定位。第九届中国卫星导航学术年会20181-5第九届中国卫星导航学术年会,2018,1-5应急条件下INS辅助的单星导航定位算法http://ir.nwpu.edu.cn/AchivementDetails/Index/1042613刘东昊, 张怡, 唐成凯,2019/11/6 15:39:02  现今的GNSS系统已经能够提供高精度的定位服务,然而在战争、小行星探测等星座型导航系统拒止条件下,可以临时快速部署单星定位系统对GNSS进行定位补充。针对应急响应导航定位需求,本文提出一种结合惯性导航系统(INS)与多普勒积分伪距差的单星定位方法,利用INS组件对动态条件下目标的单星定位结果进行解算,并利用定位目标位置的连续性,结合卡尔曼滤波理论,经过定位位置迭代和融合滤波后得到目标的定位结果,能有效提高动态环境下的单星导航的定位精度。在综合误差条件下对基于多普勒单星定位系统和伪距率辅助的单星定位系统进行对比,该算法的定位误差仅为上述两种算法的10%,能够在GNSS拒止环境下为动态目标提供的导航定位服务。第九届中国卫星导航学术年会20181-7第九届中国卫星导航学术年会,2018,1-7基于因子图的北斗导航系统协同定位方法http://ir.nwpu.edu.cn/AchivementDetails/Index/1042614翟瑞鑫, 唐成凯, 张怡,2019/11/6 15:39:02  随着北斗导航系统的逐步完善以及导航定位服务对定位精度需求的不断提高,而北斗卫星导航由于卫星轨道误差等固有误差的影响,定位精度已经达到瓶颈。本文根据北斗导航系统的特点,提出基于因子图辅助的协同定位方法。利用多个协同节点之间的测量距离值,结合因子图理论,建立置信度信息,并构建全局因子图模型及各个节点的内部因子图框架。通过和积算法实现全局函数的局部因子分解,通过迭代求解可以有效提高节点的定位目标。将本文方法与现有的定位方法进行比较,仿真结果表明本文所提出的方法在测距误差和协同节点定位误差下可以有效提高定位目标精度。第九届中国卫星导航学术年会20181-4第九届中国卫星导航学术年会,2018,1-4一种基于改进无监督学习的北斗多参考一致性监测算法http://ir.nwpu.edu.cn/AchivementDetails/Index/1042615梁宸宇, 张世铎, 王佳雄, et al. 2019/11/6 15:39:02  在GNSS完好性监测中,多参考接收机一致性监测(MRCC)的B值算法一直处于核心地位。传统GPS中的B值监测算法仅适用于地球中轨卫星,而北斗导航系统是混合星座系统,这就使得现有算法不能完全适用于北斗导航系统。为此,本文在深入分析GPS中B值监测算法的基础上,重点对北斗混合星座的多参考一致性监测方法展开讨论,提出了一种利用聚类分析方法的北斗导航系统B值监测算法,为获取更好监测性能,进一步提出了一种适用于北斗的C值辅助的B值监测算法,给出了适用于北斗导航系统的B值及C值的计算公式以及阈值的计算公式,实验结果表明,本文所提算法可以解决传统GPS的B值算法不适用于北斗卫星混合星座的问题,对建立北斗卫星导航地基增强系统的多参一致性监测体系具有很好的理论和实践意义。第九届中国卫星导航学术年会20181-6第九届中国卫星导航学术年会,2018,1-6北斗增强系统中伪卫星布局及协作定位算法研究http://ir.nwpu.edu.cn/AchivementDetails/Index/1042616王喜成, 廉保旺,2019/11/6 15:39:02  地基增强辅助系统可以增强全球导航卫星系统的定位精度以及可靠性.因而本文针对在机场复杂的地理环境,北斗系统无法全天候满足精密机场进近的要求的情况下,通过计算机模拟仿真引入单颗伪卫星与北斗卫星导航系统进行协作定位后,对定位结果的影响,并通过寻找使几何精度因子尽量小处确定伪卫星放置的最优放置几何位置.同时,研究了北斗定位系统与伪卫星构成北斗地基增强系统的协作定位算法.将其放在使系统几何精度因子尽量小的最佳几何位置,且准确测定,接收机同时接收北斗卫星的信号和伪卫星的信号,完成快速精确定位.通过实验测定,当将伪卫星放置在最佳几何位置后,可以将系统几何精度因子最大降低52.4%.系统采用的协作的定位算法可以提高定位精度,全天候满足I类精密机场进近的要求.其中水平方向定位准确度能够提升约50%,垂直方向定位准确度能够提升约80%.第九届中国卫星导航学术年会20181-6第九届中国卫星导航学术年会,2018,1-6基于主动时反的浅海目标DOA 估计优化算法http://ir.nwpu.edu.cn/AchivementDetails/Index/1042836Jing, Haixia, Wang, Haiyan, Liu, Zhengguo, 等. 2019/11/30 9:30:22将时反技术应用到浅海目标DOA 估计中,提出基于主动时间反转( active time reversal,ATR)的浅海目标DOA 估计优化方法,可有效解决多径、低信噪比条件下的目标DOA 估计问题。采用经典射线模型,结合阵列信号处理理论,建立了基于均匀线列阵的常规多径DOA 估计模型和主动时反多径DOA 估计模型,利用Capon 算法对所建模型进行了仿真验证,并做了对比分析。仿真结果表明: 在低信噪比情况下,主动时反方法可以更好地估计出目标的角度,其分辨率更高,抑制旁瓣的能力更强。西北工业大学学报2018362270-275西北工业大学学报,2018,36(2):270-275粗糙表面之间接触热阻反问题研究http://ir.nwpu.edu.cn/AchivementDetails/Index/1042941余远锋, 李泽卫, 郑晓亚,2019/12/2 10:57:31当两个固体表面相互接触时,由于接触面粗糙度的影响,界面间就形成了非一致接触,这种接触导致热流收缩,进而产生接触热阻.目前的理论研究主要集中在正问题研究,对反问题的研究相对较少.接触热阻反问题研究是通过研究部分边界温度、热流和部分测量点的温度来反演得到界面上的接触热阻.反问题研究在很多工程领域都有应用,如航空航天、机械制造、微电子等,是工程中确定接触热阻一种快速有效的方法.本文采用边界元法和共轭梯度法研究了二维空间随坐标变化的接触热阻反问题.为了验证方法的准确性和可行性,假定在已知部分测量点温度和真实接触热力学学报2018503479-486力学学报,2018,50(3):479-486Performance-improved Li-O-2 batteries by tailoring the phases of MoxC porous nanorods as an efficient cathodehttp://ir.nwpu.edu.cn/AchivementDetails/Index/1044121Yu, Hong, Khang Ngoc Dinh, Sun, Yuanmiao, et al. 2019/11/26 10:30:37Novel nitrogen-doped porous molybdenum carbide (alpha-MoC1-x and beta-Mo2C) architectures were prepared using Mo-based metal-organic frameworks (MOFs) as the precursor. The synthesized molybdenum carbides consist of numerous nanocrystals organized into micro-sized rods with interpenetrating mesoporous-channels and macroporous-tunnels along the axial direction. When employed as the cathode catalyst for Li-O-2 batteries, this dual pore configuration offers abundant active sites for the electrochemical reaction and many nucleation sites for the discharge product of Li2O2; hence, decent performances were obtained. Among the two synthesized molybdenum carbides, the alpha-MoC1-x electrode stands out as being better due to its lower charge transfer resistance (395.8 Omega compared to 627.9 Omega) and better O-2 adsorption (binding energy of -1.87 eV of alpha-(111)-Mo compared to -0.72 eV of beta-(101)-Mo). It delivered a high full discharge of 20 212 mA h g(-1) with a discharge voltage of 2.62 V at 200 mA g(-1). A good cycling stability was also obtained: i.e. 100 stable cycles with a fixed capacity of 1000 mA h g(-1) (at a current density of 200 mA g(-1)) with a charging voltage of 4.24 V and maintaining a respectable round-trip efficiency of similar to 70%.NANOSCALE2018103114877-14884NANOSCALE,2018,10(31):14877-14884