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Search Results: 1 - 10 of 77598 matches for " Wenquan Che;Edward Kai-Ning Yung;Ke Wu;Xiaodong Nie "
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Design Investigation on Millimeter-Wave Ferrite Phase Shifter in Substrate Integrated Waveguide
Wenquan Che;Edward Kai-Ning Yung;Ke Wu;Xiaodong Nie
PIER , 2004, DOI: 10.2528/PIER03082801
Abstract: In this paper,the design idea and technique of the ferrite phase shifter in substrate integrated waveguide (SIW) has been reported. The characteristics of the millimeter-wave ferrite phase shifter have been firstly calculated analytically,and the relative parameters of the device have been decided on the basis of optimization. At the same time,the design procedure of transition from ferrite phase shifter in SIW to CPW has been introduced; the agreement between the simulation results of the final integrated structure and the experimental results of an equivalent model has shown the good performance of this integrated structure.
Scattering characteristics of conducting cylinder coated with nonuniform magnetized ferrite
Hu Bin-Jie,Edward Yung Kai-Ning,Zhang Jun,Serge Toutain,
胡斌杰
,容启宁,张军,ToutainSerge

中国物理 B , 2005,
Abstract: An analytical technique, referred to as the scattering matrix method (SMM), is developed to analyse the scattering of a planar wave from a conducting cylinder coated with nonuniform magnetized ferrite. The SMM solution for the nonuniform ferrite coating can be reduced to the expressions for the scattering and penetrated coefficients in four particular cases: nonuniform magnetized ferrite cylinder, uniform magnetized ferrite-coated conducting cylinder, uniform ferrite cylinder as well as homogeneous dielectric-coated conducting cylinder. The resonant condition for the nonuniform ferrite coating is obtained. The distinctive differences in scattering between the nonuniform ferrite coating and the nonuniform dielectric coating are demonstrated. The effects of applied magnetic fields and wave frequencies on the scattering characteristics for two types of the linear profiles are revealed.
A Zero-watermarking Algorithm Based on Chaotic Modulation
一种基于混沌调制的零水印算法

XIANG Hu,CAO Han-qiang,WU Kai-ning,WEI Fang,
向华
,曹汉强,伍凯宁,魏访

中国图象图形学报 , 2006,
Abstract: In this paper, a chaotic modulation digital image zero-watermarking method is proposed. Select some low frequency wavelet coefficients of original or tested image and compute the character of the selected coefficients to create watermarking. The wavelet coefficients is randomly selected by the chaotic method. The experimental results show that the watermarking method is invisible and robust against some image processing such as median filtering, JPEG compression, additive Gaussian noise, cropping and rotation attacks and so on. This method changes the traditional doings that watermarking is embedded into images, and make the watermarked image distortion-free. If the initial value of chaos is unknown, the characteristic watermarking can not be extracted correctly.
A Survey of Attacks and Remedies on Digital Watermarking
数字水印攻击技术及对策研究

WU Kai-ning,CAO Han-qiang,ZHU Yao-ting,WANG Cheng,
伍凯宁
,曹汉强,朱耀庭,王程

计算机应用研究 , 2004,
Abstract: This paper analyses and classifies current attacks on digital watermarking.This paper also discusses relevant remedies against those attacks.It is helpful to research new digital watermarking techniques.
AN APPROACH TO EXPLOITATION OF FISHERY RESOURCES OF LUOMA LAKE
骆马湖渔业资源利用探讨

Wu Qing-long,CHEN Kai-ning,BIAN Wen-ji,
吴庆龙
,陈开宁,边文冀

资源科学 , 1999,
Abstract: Luoma Lake is a typical artificially controlled lake in north Jiangsu province.This paper elaborates the functions and the features of the lake's fishery resources and eco environment.Detailed analysis to the existing problems resulting from resources exploitation is given.Based upon which,suggestions and measures for rational fishery resources exploitation and protection are raised.
STUDIES ON REPRODUCTION DIVERSITY IN POTAMOGETON PECTINATUS
蓖齿眼子菜繁殖多样性研究

CHEN Kai-Ning QIANG Sheng LI Wen-Chao WU Qing-Long,HU Yao-Hui,
陈开宁
,强胜,李文朝,吴庆龙,胡耀辉

植物生态学报 , 2003,
Abstract: Potamogeton pectinatus is a perennial submerged aquatic macrophyte with a parvopotamid growth form. It inhabits many different environments from the south to the north in China. According to observation in Dianchi Lake, P. pectinatus is a tolerant species with wide ecological amplitude and can survive in heavy polluted waters. Presently, Dianchi Lake has been seriously polluted. Cyanobacteria blooms were serious, which led to a low transparency. While the other submerged aquatic macrophytes have disappeared, this species still occurs in Dianchi Lake. This suggests that P. pectinatus must possess various survival strategies being worthy of further research. Reproduction is a key factor influencing survival, distribution and dynamic variation of community structure. In this paper, reproduction diversity of P. pectinatus was studied through experiment and observation in situ. The results showed that pollination of P. pectinatus is by way of bubble enveloping for flowers that are underwater and pollen floating when flowers are at the water surface in sexual reproduction. The fruit-set efficiency in P. pectinatus that are underwater was low, being only 6.41% , compared to 24. 38% of flowers reaching the surface. Seed number of P. pectinatus in exposed, and sheltered or pond sites is 794, 1 627 and 2 140 per square meter, respectively. Seed germination rate of P. pectinatus was under 6% in Dianchi Lake. As a result, sexual reproduction is not important to regenerate populations of P. pectinatus . This species also possesses an extensive and effective system of asexual reproduction, through shoot fragments , rhizomes, stem tubers, root tubers and axillary shoot regeneration. The populations of this species are mainly produced from the root tubers and rhizomes. Asexual reproduction has a large contribution to population restoration during the next growth season. The main function of the seeds appears to be dispersal and long-term survival of the species. In addition, some suggestions for aquatic vegetation restoration by this species were put forward according to the results of experiment and observation.
Ammonia-Oxidizing Bacteria Community Composition at the Root Zones of Aquatic Plants after Ecological Restoration
生态修复水生植物根际氨氧化细菌的研究

XING Peng,KONG Fan-xiang,CHEN Kai-ning,CHEN Mei-jun,WU Xiao-dong,
邢鹏
,孔繁翔,陈开宁,陈美军,吴晓东

环境科学 , 2008,
Abstract: Abstract: To investigate the effects of aquatic plants on ammonia-oxidizing bacteria (AOB) at their root zones, four species of aquatic plants were selected, Phragmites communis, Typha angustifolia L., Potamogeton crispus L., and Limnanthemun nymphoides, which were widely used in ecological restorations. AOB in the samples were enumerated by most-probable-number (MPN) method. Nested polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) procedures were performed with ammonia oxidizer-selective primers. Main DGGE bands were excised from the gel and sequenced for phylogenetic affliation. Results indicate that AOB densities are always higher at the root zones of emergent plants (Phragmites communis 2.8×105cells/g and Typha angustifolia L.4.3×105 cells/g) than those of submerged and floating-leaved plant (Potamogeton crispus L. 9.3×104 cells/g and Limnanthemun nymphoides 7.7×104 cells/g). At the root zones, the oxidation-reduction potential is above zero and NH4+concentration is lower than it in the bare surface sediment. Fourteen major bands were recovered from the DGGE gel, re-amplified and sequenced. Although the identified bands have their respective similar sequences in GenBank, most of them are related to Nitrosomonas-like. This type of bacteria would play an important role of nitrogen cycle in lake sediment after ecological restoration.
The Impact of Urbanization on Groundwater Recharge: a Case Study of Shijiazhuang City
城市化对地下水补给的影响——以石家庄市为例

YU Kai-ning,
于开宁

地球学报 , 2001,
Abstract: With the rapid urbanization, groundwater has been playing a more and more important role. The study on the impact of urbanization upon groundwater recharge is of great significance not only in studying the hydrologic cycle, supply-demand balance and groundwater overexploitation but also in preventing and controlling the deterioration of groundwater quality and in revealing the relationship between overexploitation and water quality deterioration, the two main problems in groundwater environment. The study on the interaction mechanism between urbanization and groundwater constitutes a typical example. In this paper, based on the analysis of the importance of groundwater in water supply of the city as well as the exploitation and utilization of groundwater, the author studied the change of groundwater recharge under the impact of urbanization, and then discussed the impact mechanism of urbanization on groundwater recharge. On such a basis, a frame-figure on the mechanism inducing the increment of groundwater recharge was constructed. The results show:① urbanization results in the increase of groundwater recharge;②the inducing of groundwater from the well-field around the city and surface water by exploitation of groundwater and the importing of new recharge sources that results from the leakage of water-supply and water-discharge systems of the city seem to be the important mechanism that induces the recharge increase of groundwater by urbanization.
Mechanism of Groundwater Recharge Increment Induced by Urbanization
城市化诱发地下水补给增量的机理分析

YU Kai-ning~,
于开宁
,娄华君,郭振中,李涛

资源科学 , 2004,
Abstract: The study on impact of urbanization on groundwater recharge has a very important significance, not only for studying the hydrologic cycle, supply-demand balance, groundwater overexploitation, but also for preventing and controlling the deterioration of groundwater quality, and for revealing the organic relation between overexploitation and water quality deterioration, the two main problems of groundwater environment. However, up to now, it has not been determined weather the urbanization development would result in the increase or decrease of groundwater recharge, and the impact mechanism of urbanization on groundwater recharge also has not been illustrated. The study on the interaction mechanism of urbanization and groundwater in Shijiazhuang City is a typical example. In this paper, based on the analysis of the importance of groundwater in water supply of the city, and the exploitation and utilization of groundwater, the authors studied the change of groundwater recharge under the impact of urbanization, and further discussed the impact mechanism of urbanization on groundwater recharge. Finally, a frame-figure on the mechanism inducing the increment of groundwater recharge was constructed. The results show: 1) urbanization results in the increase of groundwater recharge; 2) the inducing of groundwater from the well-field around city and surface water by exploitation of groundwater, and the importing of new recharge sources resulting from the leakage of water-supply and water-discharge systems of city, is the important mechanism inducing the recharge increase of groundwater by urbanization; 3) the new recharge sources resulting from the leakage of water-supply and water-discharge systems are one of the important components which should be considered fully in the calculation of groundwater recharge in the urban districts. This study supplies a kind of theory and new approach to study hydrological cycle and water resources in the urban districts.
A first principle study on the geometry and the electronic structures of VC(001) relaxed surface
VC(001)弛豫表面构型与电子结构第一性原理研究

Zhang Yong-Fan,Ding Kai-Ning,Lin Wei,Li Jun-Qian,
章永凡
,丁开宁,林 伟,李俊篯

物理学报 , 2005,
Abstract: By using the first principle method, the geometry and electronic structures of the clean VC(001) surface are investigated. Similar to the TiC(001) surface, the relaxation of the VC(001) surface leads to the C and V atoms on the top layer move outward and inward, respectively. Results of band structure calculation show that the band structures of transition metal (001) surfaces can be well described by the rigid band model. For the VC(001) surface, the surface states are mainly located around 3 0eV below the Fermi level, and mainly originate from the 2p z orbital of C atom in the top layer. In addition, the surface states derived from the top layer V 3d orbitals are also observed near the Fermi level. Since these states contain significant contributions of those 3d orbitals vertical to the surface (3d 2 z and 3d xz /d yz ), which will play important roles in the surface reactions, it could be expected that the VC(001) surface exhibits different surface reactivity compared with the TiC(001) surface.
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