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Optimal MAC based cooperative spectrum sensing in cognitive radio networks

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science china(Information sciences) 2012年第6期55卷 1388-1396页

作者： CHEN Zhong 1,ZHANG XianDa 1 & YANG LanJuan 2.1 State Key laboratory of Intelligent technology and Systems,{2. national laboratory for Information science and technology,Department of Automation,{2. University,beijing 100084,china 2.Institute of Command Automation,PLA University of science and technology,Nanjing 2.0007,china 1. State Key laboratory of Intelligent technology and Systems Tsinghua National Laboratory for Information Science and Technology Department of Automation Tsinghua University Beijing 100084 China2. Institute of Command Automation PLA University of Science and Technology Nanjing 210007 China

This paper considers a cognitive radio (CR) system in non-ideal fading wireless channels and pro-poses cooperative spectrum sensing schemes based on coherent multiple access channels (MAC),serving as an alternative way to improve the cooperative spectrum sensing performance and provide space diversity for spec-trum *** statistics are transmitted using a common channel from the secondary users (SUs) to a fusion center (FC) where the global decision is *** optimal scaling factors of the proposed schemes are obtained by maximizing the detection probability under a target false alarm probability and a transmit power *** the proposed optimal MAC scheme has high computational complexity,a sub-optimal solu-tion based on maximization of the deflection coefficient (DC) is also *** results show that the proposed algorithms can significantly improve the spectrum sensing performance and approach the detection baseline.

关键词： cognitive radio (CR) spectrum sensing multiple access channel (MAC) deflection coefficient optimization

Eavesdropping in a quantum secret sharing protocol based on Grover algorithm and its solution

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science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 491-495页

作者： HAO Liang1, LI JunLin1 & LONG GuiLu1,2.1Key laboratory for Atomic and Molecular Nanosciences and Department of Physics, {2. University, beijing 100084, china 2.2. national laboratory for Information science and technology, beijing 100084, china 1. Key laboratory for Atomic and Molecular Nanosciences and Department of Physics Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

A detailed analysis has showed that the quantum secret sharing protocol based on the Grover algorithm (Phys Rev A, 2.03, 68: 02.306) is insecure. A dishonest receiver may obtain the full information without being detected. A quantum secret-sharing protocol is presents here, which mends the security loophole of the original secret-sharing protocol, and doubles the information capacity.

关键词： quantum secret sharing Grover algorithm quantum cryptography quantum search algorithm

Biological networks to the analysis of microarray data

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Progress in Natural science:Materials International 2006年第12期16卷 1242-1251页

作者： FANG Zhuo~1, LUO Qingming~1**, ZHANG Guoqing~1 and LI Yixue~2.*(1. Hubei Bioinformatics and Molecular Imaging Key laboratory,Huazhong University of science and {2., Wuhan 430074, china 2. Shanghai center for Bioinformation and {2., Shanghai 2.02.5, china) [a]Hubei Bioinformatics and Molecular Imaging Key laboratory Huazhong University of Science and Technology Wuhan China [b]Shanghai center for Bioinformation and technology Shanghai China

Microarray technology, which permits rapid and large-scale screening for patterns of gene expressions, usually generates a large amount of data. How to mine the biological meanings under these data is one of the main challenges in bioinformatics. Compared to the pure mathematical techniques, those methods incorporated with some prior biological knowledge generally bring better interpretations. Recently, a new analysis, in which the knowledge of biological networks such as metabolic network and protein interaction network is introduced, is widely applied to microarray data analysis. The microarray data analysis based on biological networks contains two main research aspects: identification of active components in biological networks and assessment of gene sets significance. In this paper, we briefly review the progress of these two categories of analyses, especially some representative methods.

关键词： biological networks microarray data analysis subnetwork gene set.

A simple lattice Boltzmann scheme for low Mach number reactive flows

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science china(Technological sciences) 2006年第6期49卷 714-726页

作者： CHEN Sheng1,2. LIU Zhaohui2. ZHANG Chao2. HE Zhu2. TIAN Zhiwei2. SHI Baochang 2.& ZHENG Chuguang2.1. technology center of Wuhan Iron and Steel (Group) Company, Wuhan 430080,{2. 2. State Key laboratory of Coal Combustion, Hua Zhong University of science and technology, Wuhan 430074,{2. technology center of Wuhan Iron Steel [Group] Company Wuhan 430080 China State Key laboratory of Coal Combustion Hua Zhong University of Science technology Wuhan 430074 China

For simulating low Mach number reactive flows, a simple and coupled lattice Boltzmann (CLB) scheme is proposed, by which the fluid density can bear significant changes. Different from the existing hybrid lattice Boltzmann (HLB) scheme and non-coupled lattice Boltzmann (NCLB) scheme, this scheme is strictly lattice Boltzmann style and the fluid density couples directly with the temperature. Because it has got rid of the constraint of traditional thought in lattice Boltzmann scheme,on the basis of the equality among the particle speed c, the time step △t and the lattice grid spacing △x held, both c and △t can be adjusted in this scheme according to a "characteristic temperature" instead of the local temperature. The whole algorithm becomes more stable and efficient besides inheriting the intrinsically outstanding strong points of conventional lattice Boltz-mann scheme. In this scheme, we also take into account different molecular weights of species, so it is more suitable for simulating actual low Mach number reactive flows than previous work. In this paper, we simulated a so-called "counter-flow" premixed propane-air flame, and the results got by our scheme are much better than that obtained by NCLB. And the more important thing is that the exploration in this work has offered a kind of brand-new train of thought for building other novel lattice Boltzmann scheme in the future.

关键词： lattice Boltzmann, low Mach number flows, reactive flows, simulation.

Nonlinear interactions between gravity waves and background winds

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Progress in Natural science:Materials International 2007年第6期17卷 639-644页

作者： Liu Xiao1,2.and Xu Jiyao1(1. State Key laboratory for Space Weather, center for Space {2. and Applied Research, Chinese Academy of {2.s, beijing 100080, china 2. Graduate University of Chinese Academy of {2.s, beijing 100039, china) [a]State Key laboratory for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China [b]Graduate University of Chinese Academy of sciences Beijing China

Using the nonlinear propagating gravity waves (GW) model in the two-dimensional compressible atmosphere and the linear GW theory, the process of GW propagation in different background winds, e.g. the direction of the background wind is opposite to (dead wind) or the same as (tail wind) the direction of the horizontal phase velocity of GW, is studied. The results show that the dead wind prolongs the vertical wavelength and accelerates GW propagation. Therefore, GW propagates up to a higher height becomes instable in a short time and eventually induces an inverse jet flow. Then, the vertical wavelength is becoming short due to the nonlinear interactions between GW and the inverse jet flow. The vertical wavelength and group velocity decrease after GW propagates into the tail wind. The initial instable time is delayed. Although most of GW is trapped in the instable region, some of GW propagates above the instable region. Compared with GW propagation in the tail wind, the nonlinear interactions between GW and the dead wind are also strong. In contrast, the linear GW theory predicts that GW can propagate freely in the dead wind. The vertical wavelength simulated by the nonlinear numerical model is different from that predicted by the linear theory greatly after GW propagates into the dead wind.

关键词： gravity waves background winds vertical group velocity vertical wavelength nonlinear interactions.

A new family of windows——convolution windows and their applications

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science china(Technological sciences) 2005年第4期48卷 468-480页

作者： ZHANG Jieqiu1,2. LIANG Changhong1 & CHEN Yanpu3 1. Department of Applied Math. & Phys., College of science, Airforce Engineering University, Xi’an 710051, china 2. {2. Key laboratory of Antennas and Microwave technology, Xidian University, Xi’an 710071, china 3. Computer center, Xi’an Communication College, Xi’an 710106, china 1. Department of Applied Math. & Phys. College of Science Airforce Engineering University 710051 Xi’an China 2. national Key laboratory of Antennas and Microwave {2. Xidian University 710071 Xi’an China 3. Computer center Xi’an Communication College 710106 Xi’an China

A new family of windows is constructed by convolutions via a few rectangular windows with same time width and is thus referred to as convolution windows. The expressions of the second-order up to the eighth-order convolution windows in both the time and frequency domains are derived. Their applications in high accuracy harmonic analysis of periodic signals are investigated. Comparisons between the proposed windows and some known windows with the same width shows that, when the synchronous deviation of data sampling is slight, the proposed ones have the least effect of spectral leakage. Therefore, the new windows are well suited for high accuracy harmonic analysis and parameter estimation for periodic signals. The error analysis and computer simulations show that the estimation errors, corresponding to frequency, amplitude and phase of every harmonic component of a signal, are proportional to the pth power of the relative frequency deviation in case of the pth-order convolution window is applied to windowing signal of approximately p cycles. By introducing real time adjustment in sampling interval, the proposed algorithm can adaptively trace signal frequency and lead to less sampling synchronous deviation. The proposed approach has the advantages of easy implementation and high measure precision and can be used in harmonic analysis of quasi-periodic signals whose fundamental frequency drifts slowly with time.

关键词： signal processing harmonic analysis window function convolution window synchronous error spoctral leakage

Possible mechanism of the effect of convection over Asian-Australian “land bridge” on the East Asian summer monsoon onset

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science china Earth sciences 2006年第11期49卷 1223-1232页

作者： HE Jinhai1, WEN Min2. DING Yihui3 & ZHANG Renhe2.1. Jiangsu Key laboratory of Meteorological Disaster (KLME), Nanjing Institute of Meteorology, Nanjing University of Informa- tion science and {2., Nanjing 2.0044, china 2. State Key laboratory of Severe Weather (LaSW), Chinese Academy of Meteorological sciences, beijing 100081, china 3. national Climate center, Chinese Meteorological Administration, beijing 100081, china 1. Jiangsu Key laboratory of Meteorological Disaster (KLME) Nanjing Institute of Meteorology Nanjing University of Information Science and Technology Nanjing 210044 China 2. State Key laboratory of Severe Weather (LaSW) Chinese Academy of Meteorological Sciences Beijing 100081 China 3. national Climate center Chinese Meteorological Administration Beijing 100081 China

The Asian-Australian “land bridge” is an area with the most vigorous convection in Asian monsoon region in boreal spring, where the onset and march of convection are well associated with the onset of East Asian summer monsoon. The convection occurs over Indo-china Peninsula as early as mid-April, which exerts critical impact on the evolution of monsoon circulation. Before mid-April there are primarily sensible heatings to the atmosphere over Indo-china Peninsula and Indian Peninsula, so the apparent heating ratios over them decrease with height. However, after mid-April it changes into latent heating over Indo-china Peninsula due to the onset of convection, and the apparent heating ratio increases with height in mid- and lower troposphere. The vertical distribution of heating ratio and its differences between Indo-china Peninsula and Indian Peninsula are the key factors leading to the splitting of boreal subtropical high belt over the Bay of Bengal. Such mechanism is strongly supported by the fact that the evolution of the vertical heating ratio gradient above Indo-china Peninsula leads that of 850 hPa vorticity over the Bay of Bengal. Convections over Indo-china Peninsula and its surrounding areas further increase after the splitting. Since then, there is a positive feedback lying among the convective heating, the eastward retreat of the subtropical high and the march of monsoon, which is a possible mechanism of the advance of summer monsoon and convection from Indo-china Peninsula to South china Sea.

关键词： Asian-Australian 'land bridge', tropical convection, Indo-china Peninsula, the splitting of boreal subtropical high belt, East Asian summer monsoon onset.

Re-Os(ICP-MS)dating of the massive sulfide ores from the Jinchuan Ni-Cu-PGE deposit

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science china Earth sciences 2005年第10期48卷 1672-1677页

作者： YANG Gang1,2. DU Andao1, LU Jiren3, QU Wenjun1 & CHEN Jiangfeng2.1. national Research center of Geoanalysis, {2. 100037, china 2. laboratory for Earth Material Cycling, School of Earth and Space sciences, University of science and technology of china, Hefei 2.002., china 3. Institute of Mineral Resource, Chinese Academy of Geological sciences, {2. 100037, china national Research center of Geoanalysis {2. china laboratory for Earth Material Cycling School of Earth and Space Sciences University of Science and Technology of China Hefei China Institute of Mineral Resource Chinese Academy of Geological sciences beijing{2.

Massive sulfide ore from the Jinchuan Ni-Cu-PGE deposit was dated by Re-Os technique using Carius Tube digestion, Os distillation, Re extraction by acetone and ICP-MS measurement. An isochron giving an age of 833 ± 35 Ma, initial 187Os/188Os ratio of 0.2.9 ± 0.018 (MSWD = 1.7) and γOs = 130 ± 15 is obtained. The Re-Os age obtained agrees, within analytical uncertainties, with previous SHRIMP zircon U-Pb age of 82. ± 8 Ma (n=5, MSWD = 4.3). The result suggests that the deposit was formed at Neoproterozoic and that the formation of the Jinchuan Ni-Cu-PGE sulfide deposit may be closely related to the plume activity, which were attributed to the breakup of the Rodinia supercontinent. The high γOs of the massive ores sug-gests that crustal material was involved in the formation of the Jinchuan deposit, however, the quantity of the added crustal material is less than 10%.

关键词： Jinchuan Ni-Cu-PGE deposit, Re-Os dating, ICP-MS.

Prediction method for October 2.03 solar storm

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science china(Technological sciences) 2006年第5期49卷 629-640页

作者： XIE Yanqiong1, 2. 3, WEI Fengsi1, FENG Xueshang1 & ZHONG Dingkun1, 2.1. State Key laboratory of Space Weather, center for Space {2. and Applied Research, Chinese Academy of {2.s, beijing 100080, china 2. Graduate School, Chinese Academy of {2.s, beijing 100039, china 3. Institute of Meteorology, PLA University of {2. and technology, Nanjing 2.1101, china State Key laboratory of Space Weather Center for Space Science Applied Research Chinese Academy of Sciences Beijing 100080 China Graduate School Chinese Academy of Sciences Beijing 100039 China Institute of Meteorology PLA University of Science technology Nanjing 211101 China

Aiming at two intense shock events on October 2. and 2., 2.03, this paper presents a two-step method, which combines synoptic analysis of space weather ——“observing” and quantitative prediction ——“palpating”, and then uses it to test predictions. In the first step of “observing”, on the basis of observations of the solar source surface magnetic field, interplanetary scintillation (IPS) and ACE spacecraft, we find that the propagation of the shocks is asymmetric relative to the normal direction of their solar sources, and the Earth is located near the direction of the fastest speed and the greatest energy of the shocks. As the two fast ejection shock events, the fast explosion of coronal mass of the extremely high temperature, the strong magnetic field, and the high speed background solar wind are also helpful to their rapid propagation. In the second step of “palpating”, we adopt a new membership function of the fast shock events for the ISF method. The predicted results show that for the onset time of the geomagnetic disturbance, the relative errors between the observational and the predicted results are 1.8% and 6.7%; and for the magnetic disturbance magnitude, the relative errors are 4.1% and 3.1%, re- spectively. Furthermore, the comparison among the predicted results of our two-step method with those of five other prevailing methods shows that the two-step method is advantageous. The results tell us that understanding the physical features of shock propagation thoroughly is of great importance in improving the prediction precision.

关键词： solar storm, interplanetary shock, interplanetary scintillation, two-step method, ISF method.