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Search Results: 1 - 10 of 78252 matches for " Lifu Chen "
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The impact of academic stress on medical students attending college in the Inner Mongolia Area of China  [PDF]
Jie Chen, Yanyan Wu, He Yi, Zhijun Li, Yuki Eshita, Peng Qin, Lifu Chen, Juan Sun
Open Journal of Preventive Medicine (OJPM) , 2013, DOI: 10.4236/ojpm.2013.32019

The aim of this study was to examine whether student characteristics affect the risk of health conditions, and explore whether the degree of academic stress affects the level of distress. We surveyed medical students in the Inner Mongolia Medical College China using a questionnaire. A logistic regression analysis was used to ascertain factors associated with distress. The Wilcoxon Mann-Whitney test was used to determine the relationship between distress and different academic stress levels. Of the 6044 students completing questionnaires, 47.5% self-reported distressing body symptoms induced by academic stress. Chi square tests showed statistically significant associations between distress and gender, academic stress, and residence; feeling academic stress caused a more than 1.5 times risk of distress. Gender and academic stress were significantly associated with distress in non-conditional binary logistic regression models. Compared with male students, female students was more likely to feel distress. The Wilcoxon Mann-Whitney test also showed that the distress rate increased with academic stress and a dose-response relationship between the distress rate and stress level was found. The present study indicates that it is important to reduce academic stress and manage it in order that better outcomes be achieved in regard to distress, especially in females.

Preparation and Electromechanical Properties of PVDF Matrix Piezoelectric Composites Containing Highly Oriented BaTiO3 Whiskers
Preparation and Electromechanical Properties of PVDF Matrix Piezoelectric Composites Containing Highly Oriented BaTiO_3 Whiskers

Xuetao LUO,Lifu CHEN,Xiaojun CHEN,Qianjun HUANG,
Xuetao LUO
,Lifu CHEN,Xiaojun CHEN and Qianjun HUANG

材料科学技术学报 , 2004,
Abstract: The piezoelectric composites containing highly oriented BaTiO3 whiskers as active phase and PVDF as matrix have been prepared by micro-hole extrusion and orientation in carried fibers. The morphology of oriented BaTiO3 whiskers and microstructure of the composites were observed by SEM. As for its electromechanical properties, it is found that the dielectric constant, piezoelectric constant and remnant of polarization in the BaTiO3 whisker-PVDF composite are considerably higher than that in the BaTiO3 powders-PVDF composite, while the loss factors follow the opposite trend. For the BaTiO3 whisker-PVDF composite, the values of ε, d33 and Pr parallel to the whisker orientation (normal specimen) are much higher than that perpendicular to the whisker orientation (parallel specimen). The significant effects of the connective passages of active phase on electromechanical properties of the piezoelectric composites has also been investigated.
Research on Visual model Method of Image Information Resources Management

Zhou Ning Chen Lifu Huang Zhiyi,

现代图书情报技术 , 2005,
Abstract: The management and effective utilization of digital information resources is one of the frontier subjects today, and the visualization model methods of the image management are the most important parts of it. This paper discussed how to extract, store, and transform image features, and then to build a visualized model.
Study on Machine Learning Based Automatic Text Categorization Model

Chen Lifu Zhou Ning Li Dan,

现代图书情报技术 , 2005,
Abstract: This article develops a theoretical model of machine learning based automatic text categorization, which is widely used in text categorization tasks. First, definition and architecture model of text categorization are given. Then, we choose SVM classifier as a typical example for detail analysis. Finally, a performance result is reported by the author through a Chinese text categorization experiment.
Indef inite OCSVM method for object detection in hyperspectral imagery
采用非正定OCSVM 的高光谱影像地物检测

CHEN Wei,YU Xuchu,ZHANG Lifu,ZHANG Pengqiang,

遥感学报 , 2012,
Abstract: 高斯径向基核函数是基于光谱向量间欧氏距离的度量,对于因光照强度变化而引起的地物光谱变异敏感,当同类地物光谱发生变异时,基于高斯径向基核的高光谱影像地物检测算法的性能下降.为了解决该问题,基于光谱曲线形状相似性描述提出了光谱角度余弦核测度这一非正定核函数,并应用于一种非正定OCSVM 方法的高光谱影像地物检测.最后利用两幅高光谱影像进行了实验分析,实验结果证明了本文算法的有效性.
An Analysis of the Effect of Product Packaging on Consumers’ Buying Choice in Calabar Municipality, Cross River State, Nigeria
F.L. Lifu
Asian Journal of Business Management , 2012,
Abstract: Good packaging and quality product that matches the price often calls for repeated patronage from consumers which enable the firm to stay in business. Good and attractive packaging of products creates readily available market for the firm and may help to cut down on advertising cost. The study examines the effect of good packaging of products on consumers’ buying choice as well as on impulse buying. Data were obtained from the administration of 400 copies of a structured questionnaire to consumers who come for shopping at market places, supermarkets and high traffic points across the metropolis using accidental sampling technique. The bivariate regression results revealed that 79 and 81% of consumers’ decision to buy a particular product as well as impulse buying was accounted for by the packaging style of the product, while the ANOVA results indicated that attractive packaging influenced consumers’ buying choice and impulse buying (p<0.05). In order to be sustainable and stay in business in the present day competitive and computerized market, the study advised organizations to balance both packaging and the quality of their products to meet the level cost they want as well as to build consumers’ confidence and loyalty, as consumers take product quality foremost and would not compromise quality for anythingelse.
棉花学报 , 2008,
Numerical Study on Internal Flow of Small Axial Flow Fan with Splitter Blades  [PDF]
Lifu Zhu, Yingzi Jin, Yanping Wang, Li Zhang, Yuzhen Jin
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.32A012
Abstract: The splitter blades are widely used in axial compressors and play an active role in the improvement of the overall performance of compressors. However, little research on the application of splitter blades to small axial flow fans is conducted. This paper designs a splitter blade small axial flow fan (model B) with a small axial flow fan as the prototype fan (model A) by adding short blades at the second half part of the passageway among long blades of model A. The steady simulation for the two models was conducted with the help of RNG k-ε turbulence model provided by software Fluent, and static characteristics and internal flow characteristics of the two models were compared and analyzed. Results show that splitter blades can improve the unsteady flow in the small flow rate region and also have a positive role to increase static pressure rise and efficiency in the higher flow rate region. The variation of static pressure gradient on the meridian plane in model B is well-distributed. The static pressure on the blade surface of model B distributes more uniformly. Splitter blades can suppress the secondary flow from pressure side to suction side in the leading edge because the pressure difference between suction side and pressure side in model B is generally lower than that of model A. And it also can restrain the vortex shedding and flow separation, and further it may be able to get the aerodynamic noise lower because static pressure gradient on the blade surface is well-distributed and the vortex shedding is not developed. Therefore, the performance of the fan with splitter blades is better than that of the prototype fan. The findings of this paper can be a basis for the design of high performance small axial flow fans.
陈立福, 庞科臣, 李银伟, 粟毅, 袁志辉, 王静
, PANG Kechen, LI Yinwei, SU Yi, YUAN Zhihui, WANG Jing

- , 2017, DOI: 10.11887/j.cn.201701025
Abstract: 为解决无控制点场景参考相位的快速估计问题,对影响参考相位的因素进行理论分析,给出参考相位与影响因素的解析关系式。结合系统参数进行仿真分析,分析参考相位对高程误差的影响。根据分析结果,结合外部粗精度高程数据、滤波后的干涉相位及相干系数,提出高精度参考相位快速估计算法,并给出算法详细实现流程。对实际机载双天线干涉合成孔径雷达系统获取的数据进行处理,结果表明:算法在文中的系统参数下可以达到优于2 m的相对高程精度,处理4096×6560像素的数据块时,参考相位估计速度至少增大20倍。
In dual-antenna interferometric synthetic aperture radar system, the reference phase was usually estimated by joint calibration with transferring corresponding points for the scene without ground control points, which is too time-consuming. To solve the problem, the factors influencing the reference phase were analyzed. The analytic formula was given, and simulation was done according to the system parameters. The height error caused by reference phase was analyzed. According to the analysis results, the high precision real time reference phase estimating algorithm was presented, combined with the extern coarse precision elevation, the filtered interferometric phase and coherence. The detailed flow of the algorithm was given. The processing results of the real data from airborne dual-antenna interferometric synthetic aperture radar system validate that a 2 m relative elevation precision can be achieved with the system in the paper by the algorithm presented, and the estimated speed can reach more than 20 times faster when processing the data of 4096×6560pixel.
Simulation of EO-1 Hyperion Data from ALI Multispectral Data Based on the Spectral Reconstruction Approach
Bo Liu,Lifu Zhang,Xia Zhang,Bing Zhang,Qingxi Tong
Sensors , 2009, DOI: 10.3390/s90403090
Abstract: Data simulation is widely used in remote sensing to produce imagery for a new sensor in the design stage, for scale issues of some special applications, or for testing of novel algorithms. Hyperspectral data could provide more abundant information than traditional multispectral data and thus greatly extend the range of remote sensing applications. Unfortunately, hyperspectral data are much more difficult and expensive to acquire and were not available prior to the development of operational hyperspectral instruments, while large amounts of accumulated multispectral data have been collected around the world over the past several decades. Therefore, it is reasonable to examine means of using these multispectral data to simulate or construct hyperspectral data, especially in situations where hyperspectral data are necessary but hard to acquire. Here, a method based on spectral reconstruction is proposed to simulate hyperspectral data (Hyperion data) from multispectral Advanced Land Imager data (ALI data). This method involves extraction of the inherent information of source data and reassignment to newly simulated data. A total of 106 bands of Hyperion data were simulated from ALI data covering the same area. To evaluate this method, we compare the simulated and original Hyperion data by visual interpretation, statistical comparison, and classification. The results generally showed good performance of this method and indicated that most bands were well simulated, and the information both preserved and presented well. This makes it possible to simulate hyperspectral data from multispectral data for testing the performance of algorithms, extend the use of multispectral data and help the design of a virtual sensor.
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