检索结果-南通市图书馆

维普期刊数据库博看期刊

Support vector classification algorithm based on variable parameter linear programming

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2007年第2期18卷 355-359页

作者： xiao jianhua Lin Jian Systems Science and Technology Inst. Wuyi Univ. Jiangmen 529020 P. R. China School of Economy and Management Beijing Univ. of Aeronautics and Astronautics Beijing 100083 P. R. China

To solve the problems of SVM in dealing with large sample size and asymmetric distributed samples, a support vector classification algorithm based on variable parameter linear programming is proposed. In the proposed algorithm, linear programming is employed to solve the optimization problem of classification to decrease the computation time and to reduce its complexity when compared with the original model. The adjusted punishment parameter greatly reduced the classification error resulting from asymmetric distributed samples and the detailed procedure of the proposed algorithm is given. An experiment is conducted to verify whether the proposed algorithm is suitable for asymmetric distributed samples.

关键词： Support vector machine Linear programming Classification Variable parameter.

Time-Free Solution to 3-Coloring Problem Using Tissue P Systems

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2016年第3期25卷 407-412页

作者： NIU Yunyun xiao jianhua JIANG Yun School of Information Engineering China University of Geosciences in Beijing The Research Center of Logistics Nankai University School of Computer Science and Information Engineering Chongqing Technology and Business University

In most of traditional P systems, each rule has the same execution time. That way of using the rules is not quite realistic from a biological point of view, because external conditions always change in an unpredicted manner such that different reaction may take different time to execute. In this work, we investigate the computation efficiency of tissue P systems by removing the restriction that each rule should complete in one time unit. The timed tissue P system is constructed by adding a time mapping to the rules to specify the execution time for each rule.A uniform and time-free solution to 3-coloring problem is proposed, where the execution time of the computational processes involved can vary arbitrarily and the output produced is always the same.

关键词： Membrane computing Tissue P system Time-free solution 3-Coloring problem

Influence of Golmud-Lhasa Section of Qinghai-Tibet Railway on Blown Sand Transport

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Geographical Science 2015年第1期25卷 39-50页

作者： xiao jianhua YAO Zhengyi QU Jianjun Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Dunhuang Gobi and Desert Ecology and Environment Research Station Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Gansu Center for Sand Hazard Reduction Engineering and Technology

The Qinghai-Tibet Railway(QTR) passes through 281 km of sandy land, 11.07 km of which causes serious sand damage to the railway and thus, the control of blown sand is important for the safe operation of the railway. Construction of the railway and sand prevention system greatly changed the blown sand transport of the primary surface. Effective and feasible sand-control measures include stone checkerboard barriers(SCBs), sand fences(SFs), and gravel coverings. This study simulated the embankments, SCBs and SFs of the QTR in a wind tunnel, and analyzed their respective wind profile, sand deposition, and sand-blocking rate(SBR) in conjunction with field data, aiming at studying the influence of Golmud-Lhasa section of the QTR and sand prevention system on blown sand transport. The results of wind tunnel experiments showed that wind speed increased by 67.7%–77.3% at the upwind shoulder of the embankment and decreased by 50.0%–83.3% at upwind foot of embankment. Wind speed decreased by 50.0%–100.0% after passing through the first SF, and 72.2%–100.0% after the first row of stones within the first SCB grid. In the experiment of sand deposition, the higher the wind speed, the lower the SBR of SCB and SF. From field investigation, the amount of sand blocked by the four SFs decreased exponentially and its SBR was about 50.0%. By contrast, SCB could only block lower amounts of sand, but had a higher SBR(96.7%) than SF. Although, results show that SFs and SCBs along the Golmud-Lhasa section of the QTR provide an obvious sand blocking effect, they lead to the deposition of a large amount of sand, which forms artificial dunes and becomes a new source of sand damage.

关键词： Qinghai-Tibet Railway(QTR) wind profile blown sand transport sand damage wind tunnel

Characteristics of daily extreme wind gusts on the Qinghai-Tibet Plateau, China

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2018年第5期10卷 673-685页

作者： YAO Zhengyi LI xiaoying xiao jianhua Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou 730000 China Gansu Center for Sand Hazard Reduction Engineering and Technology Lanzhou 730000 China

Severe wind is a major natural hazard and a main driver of deserdficadon on the Qinghai-Tibet Plateau. Generally, studies of Qinghai-Tibet Plateau＇s wind climatology focus on mean wind speeds and its gust speeds have been seldom investigated. Here, we used observed daily maximum gust speeds from a 95- station network over a 5-year period （2008-2012） to analyze the characteristics of extreme wind speeds and directions by fitting Weibull and Gumbel distributions. The results indicated the spatial distribution of extreme wind speeds and their direction on the Qinghai-Tibet Plateau is highly variable, with its western portion prone to greater mean speeds of extreme wind gusts than its eastern portion. Maximum extreme wind speeds of 30.9, 33.0, and 32.2 m/s were recorded at three stations along the Qinghai Tibet Railway. Severe winds occurred mostly from November to April, caused primarily by the westerly jet stream. Terrain greatly enhances the wind speeds. Our spatial analysis of wind speed data showed that the wind speeds increased exponentially with an increasing altitude. We also assessed the local wind hazard by calculating the return periods of maximum wind gusts from the observational data based on the statistical extreme value distributions of these wind speeds. Further attention should be given to those stations where the yearly maximum daily extreme wind speed increased at a rate greater than that of mean value of daily extreme wind speeds. Severe extreme wind events in these regions of the plateau are likely to become more frequent. Consequently, building structural designers working in these areas should use updated extreme wind data rather than relying on past data alone.

关键词： extreme wind gusts wind direction wind hazard wind speeds Qinghai-Tibet Plateau

Parallel Solution for Maximum Independent Set Problem by Programmable Tile Assembly

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2016年第2期25卷 203-208页

作者： HUANG Yufang xiao jianhua JIANG Keqin CHEN Zhihua School of Mathematics Southwest Jiaotong University School of Automation Huazhong University of Science and Technology Research Center of Logistics Nankai University School of Computer and Information Anqing Normal University

Parallelism in the theoretical computation mainly depends on the particular paradigm or computational environment considered, and its importance has been confirmed with the emergence of each novel computing technique. Programmable tile assembly is a novel computing technique to tackle computationally difficult problems, in which computing time grows exponentially corresponding to problematic size. The Maximum independent set(MIS) problem is a typical nondeterministic polynomial problem, which is often associated with strategy applications. In this paper, a novel approach dealing with the MIS problem is proposed based on the abstract tile assembly model, which is believed to be better than the conventional silicon-based computing in solving the same problem. The method can get the solutions of the MIS problem in θ(m + n) time complexity based on θ(mn) distinct tile types.

关键词： Molecular computing Tile assembly model Maximum independent set(MIS) Self-assembly Parallel computing

A membrane evolutionary algorithm for DNA sequence design in DNA computing

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2012年第6期57卷 698-706页

作者： xiao jianhua ZHANG XingYi XU Jin The Research Center of Logistics Nankai UniversityTianjin 300071China Key Laboratory of Intelligent Computing and Signal Processing of Ministry of Education School of Computer Science and TechnologyAnhui UniversityHefei 230039China School of Electronics Engineering and Computer Science Peking UniversityBeijing 100871China

DNA sequence design has a crucial role in successful DNA computation,which has been proved to be an NP-hard(non-deterministic polynomial-time hard) *** this paper,a membrane evolutionary algorithm is proposed for the DNA sequence design *** results of computer experiments are reported,in which the new algorithm is validated and out-performs certain known evolutionary algorithms for the DNA sequence design problem.

关键词： DNA计算进化算法序列设计 DNA序列膜设计问题多项式时间计算机实验

A non-nucleophilic gel polymer magnesium electrolyte compatible with sulfur cathode

在线全文

学校读者我要写书评

暂无评论

Nano Research 2020年第10期13卷 2749-2754页

作者： Haiyan Fan Yuxing Zhao jianhua xiao Jifang Zhang Min Wang Yuegang Zhang School of Nano-Tech and Nano Bionics University of Science and Technology of ChinaHefei 230026China i-Lab Suzhou Institute of Nano-Tech and Nano BionicsChinese Academy of SciencesSuzhou 215123China Department of Physics Tsinghua UniversityBejing 100084China

Magnesium/sulfur battery(Mg/S)has recently received wide attention due to its high theoretical energy density(3,260 Wh/L)and low *** further improve its safety and flexibility,developing a polymer electrolyte that can be compatible with both electrophilic S and Mg is ***,we report a magnesium chloride-(fluorinated tetraethylene glycolic)borate(MgCl-FTGB)based non-nucleophilic,gel-type polymer electrolyte for Mg/S battery via a facile synthetic method through commercially available *** electrolyte coupled with glass fiber allows reversible Mg deposition/dissolution(100%coulombic efficiency)with low polarization(500μA/cm^2,300/300 mV),and shows a wide electrochemical window of 4.8 V(***/Mg^2+).Mg/S battery assembled with this electrolyte can cycle over 50 times with a high specific discharge capacity retention of over 1,100 mAh/g.

关键词： magnesium/sulfur battery polymer electrolyte non-nucleophilic electrolyte safety

Wind tunnel test on the effect of metal net fences on sand flux in a Gobi Desert, China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Arid Land 2017年第6期9卷 888-899页

作者： WANG Tao QU Jianjun LING Yuquan XIE Shengbo xiao jianhua Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and Resources Chinese Academy of. Sciences Lanzhou 730000 China Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China Ningxia. University Yinchuan 750021 China Dunhuang" Gobi and Desert" Ecology and Environment Research Station Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Dunhuang 736200 China University of Chinese Academy of Sciences Beijing 100049 China

The Lanzhou-Xinjiang High-speed Railway runs through an expansive windy area in a Gobi Desert, and sand-blocking fences were built to protect the railway from destruction by wind-blown sand. However, the shielding effect of the sand-blocking fence is below the expectation. In this study, effects of metal net fences with porosities of 0.5 and 0.7 were tested in a wind tunnel to determine the effectiveness of the employed two kinds of fences in reducing wind velocity and restraining wind-blown sand. Specifically, the horizontal wind velocities and sediment flux densities above the gravel surface were measured under different free-stream wind velocities for the following conditions： no fence at all, single fence with a porosity of 0.5, single fence with a porosity of 0.7, double fences with a porosity of 0.5, and double fences with a porosity of 0.7. Experimental results showed that the horizontal wind velocity was more significantly decreased by the fence with a porosity of 0.5, especially for the double fences. The horizontal wind velocity decreased approximately 65% at a distance of 3.25 m（i.e., 13 H, where H denotes the fence height） downwind the double fences, and no reverse flow or vortex was observed on the leeward side. The sediment flux density decreased exponentially with height above the gravel surface downwind in all tested fences. The reduction percentage of total sediment flux density was higher for the fence with a porosity of 0.5 than for the fence with a porosity of 0.7, especially for the double fences. Furthermore, the decreasing percentage of total sediment flux density decreased with increasing free-stream wind velocity. The results suggest that compared with metal net fence with a porosity of 0.7, the metal net fence with a porosity of 0.5 is more effective for controlling wind-blown sand in the expansive windy area where the Lanzhou-Xinjiang High-speed Railway runs through.

关键词： wind-blown sand wind tunnel experiment porous fence flow field sediment flux density Lanzhou-Xinjiang High-speed Railway Gobi Desert

Morphology and formation mechanism of sand shadow dunes on the Qinghai-Tibet Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2015年第1期7卷 10-26页

作者： jianhua xiao JianJun QU ZhengYi YAO YingJun PANG KeCun ZHANG Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences Dunhuang Gobi and Desert Ecology and Environment Research Station Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Gansu Center for Sand Hazard Reduction Engineering and Technology

The formation and development of dunes depend on wind-blown sand movement which is affected by the characteristics of sand material, topography, wind regimes and other factors. In this paper, we investigated two sand shadow dune groups in Shigatse and Za＇gya Zangbo of Tibet and an individual dune in Da Qaidam of Qinghai, and analyzed their topographies and morphologies, and the physical characteristics of the sand, wind regime and sand transport. Formed under harsh conditions behind hills, these mature sand shadow dunes are hundreds of meters long, have significant ridges and crescent dunes downwind, and have a hill pass on one or both sides. Wind tunnel experiments revealed that the hill gap and wind velocity are important factors in the formation of these dunes Sand shadow dunes formed only when the gap spacing is two-thirds of the hill height. When wind velocities are 20 m/s, the sand body is divided into two parts. The hill pass allows the transport of sand by wind, creating a ＂nar- row-pipe effect＂, which causes the transported material to gradually accumulate in the center of the shadow zone. We observed that the following are needed for sand shadow dunes to form：（1） strong winds, sufficient sand, suitable obstacles and a dry climate; （2） one or both sides of the obstacle forming the shadow zone must have a hill pass; and （3） the windward side of the obstacle must have a wide, flat area, providing adequate spacing for wind flow and transport of material and the leeward side must have a sufficiently broad, flat area to allow the release of the transported material. Research results on these newly discovered dunes on the Qinghai-Tibet Plateau could contribute to the understanding of dune geomorphology.

关键词： sand shadow dune morphology aeolian landform wind tunnel Qinghai-Tibet Plateau