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Discussion on data-security of space-earth integrated network and analysis ofspace communications protocol standards

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Journal of Systems Engineering and Electronics 2005年第2期16卷 290-294页

作者： LiZehui liuyong SunJin DepartmentofArmamentEngineering NavalAeronauticalEngineeringAcademyYantai264001P.R.China ShandongInstituteofAerospaceElectronicTechnology Yantai264000P.R.China

The architecture and protocols of Internet can't work well in space environments. To form a reliable and safe space network, characteristics of space communication network one discusse, brief synthesis is performed for consultative committee for space data system (CCSDS) space communications protocol standards (SCPS), and a model accounting for data security problem of space-earth integrated network is provided.

关键词： space network protocol security.

Kinetics and Mechanism of Dechlorination of o-Chlorophenol by Nanoscale Pd/Fe

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Chemical Research in Chinese Universities 2004年第1期20卷 73-76页

作者： WEIJian-jun XUXin-hua liuyong DepartmentofEnvironmentalEngineering ZhejiangUniversityHangzhou310027P.R.China

Nanoscale Pd/Fe bimetallic particles were synthesized with an efficient method to dechlorinate o-chlorophenol. The nanoscale Pd/Fe particles were determined by transmission electron microscopy and BET specific surface area analysis. Most of the particles are in the size range of 20—100 nm. The BET specific surface area of synthesized nanoscale Pd/Fe particles is 12.4 m 2/g. In contrast, a commercially available fine iron powder(<100 mesh) has a specific surface area of 0.49 m 2/g. Batch studies demonstrated that the nanoscale particles can effectively dechlorinate o-chlorophenol. The dechlorination reaction takes place on the surface of synthesized nanoscale Pd/Fe bimetallic particles in a pseudo-first order reaction. The surface-area-normalized rate coefficients(k_ SA) are comparable to those reported in the literature for chlorinated ethenes. The observed reaction rate constants(k_ obs) are dominated by the mass fraction of Pd and the mass concentration of the nanoscale Pd/Fe particles.

关键词： Nanoscale Pd/Fe Dechlorination o-Chlorophenol Kinetics Mechanism

A New Low-Impedance High Power Microwave Source

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Chinese Physics Letters 2004年第6期21卷 1111-1113页

作者： HEJun-Tao ZHONGHui-Huang liuyong-Gui CollegeofScience NationalUniversityofDefenseTechnologyChangsha410073

We propose a new low-impedance high power microwave source based on the axial transit time effect, i.e.a low-impedance axial transit-time oscillator. The analysis and simulation are carried out to investigate the characteristics of this new configuration. In the numerical simulation, the microwave output peak power of 6GW is obtained with an electron beam in the electron energy 580keV and in the beam current 20kA. The diode impedance is 29Ω. The power of the input electron beam is 11.6GW. The beam-to-microwave power conversion efficiency is 51.7%. The frequency is 3.9GHz by numerical simulation.

关键词： Electron beams

A New Method for Increasing Output Power of a Three-Cavity Transit-Time Oscillator

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Chinese Physics Letters 2004年第7期21卷 1302-1305页

作者： HEJun-Tao ZHONGHui-Huang QIANBao-Liang liuyong-Gui CollegeofScience NationalUniversityofDefenseTechnologyChangsha410073

We propose a new method to increase the output power of a three-cavity transit-time oscillator (TC-TTO). Conventional transit-time effect oscillators, such as the split-cavity oscillator (SCO), super-Reltron, and TC-TTO (or double-foil SCO), etc., have a common feature that the span of any modulating cavity is uniform. The new method is to vary the three-cavity spans from uniform to nonuniform. Its configuration is called the nonuniform three-cavity transit-time oscillator (NTC-TTO). Numerical simulations show that the electron-beam is modulated more deeply in certain NTC-TTOs than that in the TC-TTO with the same whole modulating length, and the output microwave power in certain NTC-TTOs is higher than that in the TC-TTO. The experimental results are in agreement with those of the numerical simulations. The results show that the new method can increase the output power of a microwave tube based on the TC-TTO.

关键词： Microwave tubes

Aging Behavior of Cu-Cr-Zr-Ce Alloy

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材料热处理学报 2004年第5期25卷 612-614页

作者： liuyong LIUPing SUJuan-hua TIANBao-hong LIWei SchoolofMaterialScience＆Engineering HenanUniversityofScience＆TechnologyLuoyangChina SchoolofMaterialScience＆Engineering Xi＇anUniversityofTechnologyXi＇anChina／SchoolofMaterialScience＆EngineeringHenanUniversityofScience＆TechnologyLuoyangChina

The aging properties of Cu-0.35Cr-0.038Zr-0.055Ce alloy are studied. The results show that can obtain higher electrical conductivity and microhardness after solutioned at 920°Cfor Ih, and aged at 500°C. The process of precipitation of the secondary phase can be accelerated with cold deformation before aging, so properties of the alloy are improved. Upon aging at 500°C for 30 minutes after 60% cold deformation, the values of electrical conductivity and microhardness are 69.0%IACS and 152HV respectively, but they are only 66.2%IACS and 136HV upon directly aging after solution. With the addition of a trace of rare earth element Ce, the value of microhardness of Cu-0.35Cr-0.038Zr alloy increases 18-25HV, while the value of electrical conductivity drops a little.

关键词： Cu-Cr-Zr-Ce合金稀土冷变形电导率显微硬度

Enhancement of the hydrogen evolution performance by finely tuning the morphology of Co-based catalyst without changing chemical composition

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Nano Research 2019年第1期12卷 191-196页

作者： Wenling Gu liuyong Hu Changshuai Shang Jing Li Erkang Wang State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Chinese Academy of Sciences Beijing 100049China

Transition-metal phosphides, as the promising alternatives to noble metal catalysts, have been widely used as efficient electrocatalysts for hydrogen evolution reaction (HER). In this work, three kinds of cobalt-8-hydroxyquinoline (Coqx) with different size and nanostructures are synthesized by varying the hydrothermal conditions, which was named as Coqx-L, Coqx-M and Coqx-S according to the decreased size. Accordingly, the CoxP/NC with three different size nanostructures (CoxP/NC-L, CoxP/NC-M and CoxP/NC-S) are obtained by the sequential carbonization and phosphidation of Coqx. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results imply the identical chemical composition in these catalysts with different morphologies. Thus, systematic study is carried out to reveal the relationship between catalytic performance and morphologies of materials with the same chemical composition. The experimental result indicates that the morphology of Cc)xP/NC plays a crucial role on the surface area and electron transfer. Finally, the catalyst of CoxP/NC-S with the smallest size nanostructrue exhibits the best HER performance with a low overpotential at current density of 10 mA/cm^2 (n = 56.9 and 115.6 mV) and a small Tafel slope (52.3 and 69.3 mV/dec) in both 0.1 M HCIO4 and 1.0M KOH as well as long-term stability.

关键词： electrocatalyst hydrogen evolution reaction transition-metal phosphides

Global Trends in Dam Removal and Related Research: A Systematic Review Based on Associated Datasets and Bibliometric Analysis

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Chinese Geographical Science 2019年第1期29卷 1-12页

作者： DING liuyong CHEN Liqiang DING Chengzhi TAO Juan Yunnan Key Laboratory of International Rivers and Transboundary Eco-security Yunnan University Institute of International Rivers and Eco-security Yunnan University

Dam removal has been increasingly reported globally and is becoming an important approach for river management, restoration and environmental conservation in damming rivers. However, current limited knowledge of global trends in dam removal and related research may be potentially biased in terms of the geographic distribution and organisms studied. Such bias could mislead dam removal planning and management in different areas and ecological conservation for different taxa. In this study, we quantitatively and qualitatively analyzed datasets of dam removal and publications of dam removal research using bibliometric methods. A total of 1449 dam removal documents were published from 1953 to 2016. Trends, current hotspots and future directions of dam removal research were identified. The results from this study reveal that dam removal largely occurred in the North America and Europe, and most of the removed dams were small and old dams. With respect to the topic analysis, more dam removal studies should focus on the responses of a wide range of organisms, not only fish, as well as the interspecies relationships, food webs and ecosystem structures and functions. Based on our findings, we also provide some suggestions for future dam removal planning and analysis.

关键词： dam demolition literature research topics weir

Cloning and Characterization of the fecC Gene Necessary for Optimal Growth under Iron-Deficiency Conditions in the Cyanobacterium Anabaena sp. PCC7120

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Wuhan University Journal of Natural Sciences 2004年第4期9卷 498-502页

作者： xuwen-liang liuyong-ding ZHANGCheng-cai LIJuan CollegeofLifeSciences CentralChinaNormalUniversityWuhan430079HubeiChina InstituteofHydrobiology ChineseAcademyofSciencesWuhan430072HubeiChina CollegeofLifeSciencesandTechnology HuazhongAgriculturalUniversityWuhan430070HubeiChina CollegeofLifeSciences CentralChinaNormalUniversityWuhan430079HubeiChina

ThefecC gene encoding a putative iron (III) dicitrate transporter was cloned from nitrogen-fixing cyanobacteriumAnabaena sp. PCC 7120, and inactivated. The mutant grows normally in medium with NO 3 ? , NH 4 + or without combined nitrogen. But in iron-deficient medium, the mutant grows slowly. Photosynthetic properties were compared between the mutant and the wildtype strain, the content of photosynthetic pigments in the mutant is lower than that of the wild-type. The results of RT-PCR experiments show that thefecC gene is expressed under iron-deficient conditions, but is not expressed under iron-replete conditions. These results revealed thatfecC gene product is required for optimal growth under iron-deficient conditions inAnabaena sp. PCC 7120. Key words Anabaena sp. PCC 7120 - fecC - iron deficiency - photosynthetic properties - expression CLC number Q 933 Foundation item: Supported by the National Natural Sciences Foundation of China (30070154), the Frontier Science Projects Program of the Institute of Hydrobiology, the Chinese Academy of Sciences (220316), State Key Project on Cyanobacterial Bloom Control in Lake Dianchi (K99-05-35-01)Biography: XU Wen-liang (1974-), male, Ph. D, research direction: molecular genetics of cyanobacteria.

关键词： Anabaena sp. PCC 7120 fecC iron deficiency photosynthetic properties expression

Asymptotic stability in a mosquito population suppression model with time delay

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International Journal of Biomathematics 2023年第4期16卷 1-19页

作者： Yuanxian Hui Zhong Zhao Qiuying Li liuyong Pang School of Mathematics and Statistics Huanghuai University ZhumadianHenan 463003P.R.China

In this paper,a delayed mosquito population suppression model,where the number of sexually active sterile mosquitoes released is regarded as a given nonnegative function,and the birth process is density dependent by considering larvae progression and the intra-specific competition within the larvae,is developed and studied.A threshold value r^(*)for the releases of sterile mosquitoes is determined,and it is proved that the origin is globally asymptotically stable if the number of sterile mosquitoes released is above the threshold value r^(*).Besides,the case when the number of sterile mosquitoes released stays at a constant level r is also *** the special case,it is also proved that the origin is globally asymptotically stable if and only if r>r^(*)and that the model exhibits other complicated dynamics such as bi-stability and semi-stability when r≤r^(*).Numerical examples are also provided to illustrate our main theoretical results.

关键词： Global asymptotic stability delay differential equation mosquito population suppression sterile mosquitoes mosquito-borne diseases