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Search Results: 1 - 10 of 78533 matches for " ZhiGuo Chen "
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A remark on “an approximation condition and extremal quasiconformal extension”
Jixiu Chen,Zhiguo Chen
Chinese Science Bulletin , 1997, DOI: 10.1007/BF02882637
Boundary Behavior of μ(z)-homeomorphisms
μ(z) -同胚的边界性质

Chen Zhiguo,

数学物理学报(A辑) , 2007,
Abstract: 该文讨论μ(z)-同胚的边界性质.给出了一个充分条件,使得上半平面的μ(z)-自同胚可以拓扑地向边界延拓.用μ(z)-同胚的伸张函数估计了ρ-函数.
Complete Tunneling of Light Through Mu-Negative Media
Wei Tan;Zhiguo Wang;Hong Chen
PIER M , 2009, DOI: 10.2528/PIERM09060201
Abstract: We demonstrate complete tunneling of light through large-scale mu-negative media, which has negative permeability but positive permittivity, by constructing a quasi-one-dimensional structure with side branches. For the structure with a single side branch, there always exists a transmission peak which can be easily tuned by varying the parameters of the side branch. For the structure with periodic array of side branches, the transmission peak is enlarged to a band, which exhibits left-handedness, and can be tuned by changing the distance between two neighboring side branches and the length of the side branch.
Optimization of Fermentation Medium for Producing α-Hydroxyphenylacetic Acid by Using Plackett-Burman Design and Response Surface Methodology  [PDF]
Zhiguo Hou, Bingmei Chen, Jing Lan, Yueman Liu, Xiaoping Xu, James Yu Gu, Junjie Gu
American Journal of Analytical Chemistry (AJAC) , 2013, DOI: 10.4236/ajac.2013.410070

Plackett-Burman design and response surface methodology were applied in order to optimize the fermentation medium of (R)-α-hydroxyphenylacetic acid ((R)-HPA) producing Bacillus sp. HZG-19. The factors playing important roles in the production of (R)-HPA were selected based on Plackett-Burman design. The path of steepest ascent was undertaken to optimize said fermentation medium. Finally, the optimal levels of the factors with the greatest change in regard to product yield were further optimized using Box-Behnken and response surface analysis. The optimal conditions were found to be as follows: casein peptone 30.49 (g × L-1), glycerol 14.09 (g × L-1), KH2PO4 0.1345 (g × L-1), K2HPO4 0.01

A New High-Speed Foreign Fiber Detection System with Machine Vision
Zhiguo Chen,Wenbo Xu,Wenhao Leng,Yi Fu
Mathematical Problems in Engineering , 2010, DOI: 10.1155/2010/398364
Abstract: A new high-speed foreign fiber detection system with machine vision is proposed for removing foreign fibers from raw cotton using optimal hardware components and appropriate algorithms designing. Starting from a specialized lens of 3-charged couple device (CCD) camera, the system applied digital signal processor (DSP) and field-programmable gate array (FPGA) on image acquisition and processing illuminated by ultraviolet light, so as to identify transparent objects such as polyethylene and polypropylene fabric from cotton tuft flow by virtue of the fluorescent effect, until all foreign fibers that have been blown away safely by compressed air quality can be achieved. An image segmentation algorithm based on fast wavelet transform is proposed to identify block-like foreign fibers, and an improved canny detector is also developed to segment wire-like foreign fibers from raw cotton. The procedure naturally provides color image segmentation method with region growing algorithm for better adaptability. Experiments on a variety of images show that the proposed algorithms can effectively segment foreign fibers from test images under various circumstances.
Pollution characteristics and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the southern part of the Haihe River system in China
Feng Liu,JingLing Liu,QiuYing Chen,BinBin Wang,ZhiGuo Cao
Chinese Science Bulletin , 2013, DOI: 10.1007/s11434-013-5677-6
Abstract: The southern part of the Haihe River system, the largest river system in the Haihe River Basin, is important to maintain a healthy ecosystem and safe drinking water as well as for the economic development of China. To assess the effect of rapid industrialization and urbanization on the pattern of polycyclic aromatic hydrocarbon (PAH) contamination, the PAH pollution characteristics of the southern part of the Haihe River system was investigated. Sixteen PAHs in surface sediments samples collected from 24 sites covering the southern part of the Haihe River system from the upstream to the estuaries were detected and analyzed. The total PAH concentration ranged from 258.77 to 11296.66 ng/g dry weight. On average, 2-, 3-, 4-, 5- and 6-ring PAHs comprised 25.32%, 27.22%, 22.62%, 14.89% and 9.96% of the total PAHs, respectively. Sites with high concentrations were concentrated in the Fuhe River, Fuyang River and Wei River, which are located near cities. A risk quotient (RQ) was used to assess the ecological risk of PAHs. The mean values of the RQ(MPCs) of individual PAHs were lower than 1.00, except for those of naphthalene (2.00) and pyrene (1.67). The RQΣPAHs calculated for the samples indicated that the Xidayang reservoir and the estuary of the Ziya River were determined to be at a low risk level, while Baoding City, Handan City and Aixinzhuang were determined to be at a high risk level.
Variations of organic carbon isotopic composition and its environmental significance during the last glacial on western Chinese Loess Plateau
Fahu Chen,Zhiguo Rao,Zhang Jiawu,Jin Ming,Ma Jianying
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-006-2003-6
Abstract: A high-resolution loess section in the western Chinese Loess Plateau, Yuanbao Section, was sampled for organic carbon isotopic analyses. The soil organic carbon isotope (δ 13Corg) varied between 22.6‰ and 27.5‰ during the last glacial at the section. During the last interstadial, the δ 13Corg values were more negative than those in both early and late periods of the last glacial by 4‰ The isotopic composition indicates a coupled response of the pure C3 plants to the temperature, precipitation and the concentration of atmospheric CO2. Decrease in temperature and the atmospheric CO2 concentration from the last interstadial to Last Glaicial Maximum (LGM) caused the organic carbon isotopes to become positive by 1.5‰–2.0‰ The amplitude of 4‰ in the δ 13Corg variation during the last glacial should be mainly caused by the precipitation change. Therefore, the δ 13Corg variations of the Yuanbao Section during the last glacial period documented the large-amplitude fluctuation of the monsoon precipitation, which is estimated to be 250–310 mm more during the last interstadial than that in the LGM, and 100 mm more than that during early last glacial. The rapid changes of the monsoon precipitation on millennial scale during the last glacial have also been recorded in the isotopic variations in Yuanbao loess section. As the isotopic composition varies complicatedly as shown in the loess-paleosol sequence, it cannot be simply attributed to the abundances of C3 and C4 plants or be used as an indicator of the summer monsoon variations.
Multiple Logistic Regression Analysis of Risk Factors Associated with Denture Plaque and Staining in Chinese Removable Denture Wearers over 40 Years Old in Xi’an – a Cross-Sectional Study
Yanwei Yang, Hongchen Zhang, Zhiguo Chai, Jihua Chen, Shaofeng Zhang
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0087749
Abstract: Background Removable dentures are subject to plaque and/or staining problems. Denture hygiene habits and risk factors differ among countries and regions. The aims of this study were to assess hygiene habits and denture plaque and staining risk factors in Chinese removable denture wearers aged >40 years in Xi’an through multiple logistic regression analysis (MLRA). Methods Questionnaires were administered to 222 patients whose removable dentures were examined clinically to assess wear status and levels of plaque and staining. Univariate analyses were performed to identify potential risk factors for denture plaque/staining. MLRA was performed to identify significant risk factors. Results Brushing (77.93%) was the most prevalent cleaning method in the present study. Only 16.4% of patients regularly used commercial cleansers. Most (81.08%) patients removed their dentures overnight. MLRA indicated that potential risk factors for denture plaque were the duration of denture use (reference, ≤0.5 years; 2.1–5 years: OR = 4.155, P = 0.001; >5 years: OR = 7.238, P<0.001) and cleaning method (reference, chemical cleanser; running water: OR = 7.081, P = 0.010; brushing: OR = 3.567, P = 0.005). Potential risk factors for denture staining were female gender (OR = 0.377, P = 0.013), smoking (OR = 5.471, P = 0.031), tea consumption (OR = 3.957, P = 0.002), denture scratching (OR = 4.557, P = 0.036), duration of denture use (reference, ≤0.5 years; 2.1–5 years: OR = 7.899, P = 0.001; >5 years: OR = 27.226, P<0.001), and cleaning method (reference, chemical cleanser; running water: OR = 29.184, P<0.001; brushing: OR = 4.236, P = 0.007). Conclusion Denture hygiene habits need further improvement. An understanding of the risk factors for denture plaque and staining may provide the basis for preventive efforts.
Deep Attributes from Context-Aware Regional Neural Codes
Jianwei Luo,Jianguo Li,Jun Wang,Zhiguo Jiang,Yurong Chen
Computer Science , 2015,
Abstract: Recently, many researches employ middle-layer output of convolutional neural network models (CNN) as features for different visual recognition tasks. Although promising results have been achieved in some empirical studies, such type of representations still suffer from the well-known issue of semantic gap. This paper proposes so-called deep attribute framework to alleviate this issue from three aspects. First, we introduce object region proposals as intermedia to represent target images, and extract features from region proposals. Second, we study aggregating features from different CNN layers for all region proposals. The aggregation yields a holistic yet compact representation of input images. Results show that cross-region max-pooling of soft-max layer output outperform all other layers. As soft-max layer directly corresponds to semantic concepts, this representation is named "deep attributes". Third, we observe that only a small portion of generated regions by object proposals algorithm are correlated to classification target. Therefore, we introduce context-aware region refining algorithm to pick out contextual regions and build context-aware classifiers. We apply the proposed deep attributes framework for various vision tasks. Extensive experiments are conducted on standard benchmarks for three visual recognition tasks, i.e., image classification, fine-grained recognition and visual instance retrieval. Results show that deep attribute approaches achieve state-of-the-art results, and outperforms existing peer methods with a significant margin, even though some benchmarks have little overlap of concepts with the pre-trained CNN models.
Study on the Inventory Routing Problem of Refined Oil Distribution Based on Working Time Equilibrium  [PDF]
Zhenping Li, Zhiguo Wu
American Journal of Operations Research (AJOR) , 2016, DOI: 10.4236/ajor.2016.61003

Taking the distribution route optimization of refined oil as background, this paper studies the inventory routing problem of refined oil distribution based on working time equilibrium. In consideration of the constraints of vehicle capacity, time window for unloading oil, service time and demand of each gas station, we take the working time equilibrium of each vehicle as goal and establish an integer programming model for the vehicle routing problem of refined oil distribution, the objective function of the model is to minimize the maximum working time of vehicles. To solve this model, a Lingo program was written and a heuristic algorithm was designed. We further use the random generation method to produce an example with 10 gas stations. The local optimal solution and approximate optimal solution are obtained by using Lingo software and heuristic algorithm respectively. By comparing the approximate optimal solution obtained by heuristic algorithm with the local optimal solution obtained by Lingo software, the feasibility of the model and the effectiveness of the heuristic algorithm are verified. The results of this paper provide a theoretical basis for the scheduling department to formulate the oil distribution plan.

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