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Search Results: 1 - 10 of 23769 matches for " Zheng Xiaojing "
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Characteristics of near-surface turbulence during a dust storm passing Minqin on March 19, 2010
XiaoJing Zheng,JingHong Zhang
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-010-4091-6
Abstract: Twelve-hour real-time and synchronous measurements of the three-dimensional components of the near-surface turbulence at four heights (8, 16, 32 and 47 m) during a dust storm are obtained by sonic anemometers for the first time. The experimental results show that (1) the mean vertical velocities at all four heights have considerably positive values during the dust storm, illustrating a strong upward flow near the surface; (2) during the dust storm, the mean vertical velocity is higher at 8 m than at 16 and 32 m, implying that the convection is stronger at 8 m than at the other two heights; and (3) when the longitudinal velocity is a maximum, the mean of the vertical components of wind velocities at 8 m is a minimum and the standard deviation is a maximum, which reveals weaker vertical convection during the period of greatest dust storm intensity, while the turbulence intensity contrarily increases, which may result in more entrainment of surface dust. The analysis results also show that the standard deviations of the longitudinal and vertical velocities increase as the mean inflow velocity increases, but the standard deviation of the lateral velocity is hardly affected by the mean inflow velocity. Based on the calculated skewness and kurtosis of the longitudinal, vertical and lateral velocities every 20 min at different heights, it is seen that all three components obviously fluctuate with height, which further indicates the importance of performing real-time and synchronous measurements at different heights near the surface during a dust storm so as to reveal the three-dimensional turbulence structure accurately.
A laboratory test of the electrification phenomenon in wind-blown sand flux
Ning Huang,Xiaojing Zheng
Chinese Science Bulletin , 2001, DOI: 10.1007/BF03183279
Abstract: The measured data in the wind-tunnel tests show that the wind-blown sand particles acquired a negative charge when their diameters are smaller than 250 μm and positive charge when their diameters are larger than 500 μm, which confirms Latham’s assumption that the large particles in wind-blown sand flux acquired positive charge while negative charge developed on small ones. In the meanwhile, the measured data also show that the average charge-to-mass ratio for wind-blown sand particles decreases with the increase of the particle diameter and the wind velocity, and increases with the rise of height. The electric field in wind-blown sand flux is mainly formed by the moving charged sand particles. Its direction is vertical to the Earth’s surface and upward, which is opposite to that of the fair-weather field. The electric field increases with wind velocity and height increasing. These experimental results will lay the foundation for developing the theoretical analysis of the electrification phenomenon in wind-blown sand flux.
A laboratory test of the electrification phenomenon in wind-blown sand flux

HUANG Ning,ZHENG Xiaojing,

科学通报(英文版) , 2001,
Abstract: The measured data in the wind-tunnel tests show that the wind-blown sand particles acquired a negative charge when their diameters are smaller than 250 ?m and positive charge when their diameters are larger than 500 ?m, which confirms Latham’s assumption that the large particles in wind-blown sand flux acquired positive charge while negative charge developed on small ones. In the meanwhile, the measured data also show that the average charge-to-mass ratio for wind-blown sand particles decreases with the increase of the particle diameter and the wind velocity, and increases with the rise of height. The electric field in wind-blown sand flux is mainly formed by the moving charged sand particles. Its direction is vertical to the Earth’s surface and upward, which is opposite to that of the fair-weather field. The electric field increases with wind velocity and height increasing. These experimental results will lay the foundation for developing the theoretical analysis of the electrification phenomenon in wind-blown sand flux.
The feature of stratification in the blowing sand cloud
Xiaojing Zheng,Lihong He,Jianjun Wu
Chinese Science Bulletin , 2003, DOI: 10.1360/02wd0252
Abstract: The profiles of particle concentration in saltation layer versus height are calculated, by the motion equations for a saltating grain in conjunction with different probability distribution functions of the vertical liftoff velocities of grains and an empirical expression of wind velocity. The numerical results demonstrated that the stratification phenomenon exists in the particle concentration profiles and showed increasing, saturating and decreasing features, respectively, when the probability distribution functions of liftoff velocities adopted in the calculation are similar to a normal distribution or a two-parameter gamma distribution. When the distribution function of liftoff velocities is taken as an exponential form, the profile of particle concentration decreases monotonically. A numerical simulation of mass flux of grains, performed by the model suggested in this paper, is in reasonable accordance with the measured data.
Application of Capture and Recapture Method for Estimating the Population Size of Men Who Have Sex with Men in Chiang Mai, Thailand  [PDF]
Phrutthinun Surit, Ning Zheng, He Yi, Xiaojing Yu, Watcharee Srithong, Saisiri Mirasena, Wutthichai Jariya
World Journal of AIDS (WJA) , 2016, DOI: 10.4236/wja.2016.64022
Abstract: Background: Men who have sex with men (MSM) are highly vulnerable to HIV infection, but this population can be particularly difficult to reach in Thailand. This study aimed to estimate the number of MSM in Chiang Mai Thailand, in order to plan HIV control and prevention. Methods: The total of 348 potential MSM were identified at eight contact locations, including two public parks, two bars, two massage parlors and two pubs in Chiang Mai. Trained 16 research enumerators and 16 enumerators were trained to extend a recruitment of brooches to MSM. The MSMs were captured one week apart. A record was kept of when, where and by whom the invitation was extended and received, and of refusals. The total estimate of MSM was derived from capture-recapture calculation. Results: The total MSM in Chiang Mai Thailand estimated by capture and recapture method was 733 (95%CI = 480 - 948) or the estimate was 7.3% (95%CI = 7.1% - 14.1%). Conclusions: Capture and recapture method can be used to enumerate and provide accurate and reliable estimates of the MSM population in any area, provided that certain conditions are controlled. MSM who are engaged in personal community represent a sizeable population who urgently need to be targeted by HIV and STDs prevention strategies.
Risk Factors Affecting Condom Use among Royal Thai Army Conscripts in Thailand  [PDF]
Phrutthinun Surit, Wutthichai Jariya, Ning Zheng, He Yi, Xiaojing Yu, Watcharee Srithong, Saisiri Mirasena
World Journal of AIDS (WJA) , 2017, DOI: 10.4236/wja.2017.72009
Abstract: The study was conducted to explore factors associated with condom use of young Thai men conscripts. Methods: A cross-sectional study was conducted. Participants were 159 conscripts in second year who served in the Royal Thai Army by lottery method. Demographic data, sexual history including condom use, HIV and STDs and knowledge were collected using a self-administered questionnaire. Logistic regression was used to analyze the data. Results: Condom use at the last sex was 41.18% of the conscripts aged 20 - 27 years and secondary school education completed of 74.2%. 25.78% had experience with drugs used but injection was rare (6.9%). Age at the first sex was reported lowest at 11 years, 9.4% reported first sex with men and 21.38% were married. The participants have sexual history (last six months) with female only of 83.2%, male only of 4.1% and both of 14.6%. Among these only 12.6% reported every time of condom use and 19.5% never used condom. Older age, higher education, drinking alcohol, drugs use and higher knowledge were associated with condom use with statistical significance. Conclusions: Condom use among male Thai conscripts was low. Education and a condom use program are urgently needed to prevent future spread of HIV and STDs.
Microfinance in Fisheries in China  [PDF]
Xiaojing Wang
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.35001
Abstract:

Because of lack of collateral and formal financial information, family aquacultures and small boat owners find it difficult to get loans from formal financial institutions. Fishery microfinance can partly solve the information asymmetry and incomplete contract problems in rural financial market, and it is an effective complement to formal fishery finance. The service object of fishery microfinance is mainly micro-enterprises in fisheries, including family aquacultures and small fishing boats. Fishery microfinance providers include formal financial institutions and many kinds of micro-financial institutions, among which China Fishery Mutual Insurance Association (FMIA) is the most famous one. Although micro-finance has a 20-year-history in China, there are still some problems that block its advance. The market is huge, but the existing providers are not providing good services and most are not sustainable. There is still a long way towards commercial operation and financial sustainability.

Research on the Innovation of Employment Guidance in Universities under the Integrate Innovation & Entrepreneurship Education Background
—Based on the Survey of Universities in North Henan
 [PDF]

Xiaojing Liu
Creative Education (CE) , 2017, DOI: 10.4236/ce.2017.815170
Abstract: The background of “Innovation and Entrepreneurship” education puts forward higher requirements for employment guidance in colleges and universities. This paper investigates the current status of employment guidance in Local Universities in North Henan by questionnaire and interview. It indicates that several problems exist in the content and method, ideas and team of university employment guidance. Therefore, on the base of investigation, practice and rethink, this article summarizes?and drawson the experiences of employment guide, and puts?forward the innovational suggestions and strategies of employment guide in domestic colleges and universities. Employment guidance will be better by constructing a diversified employment guidance platform, enriching the contents and methods of employment guidance, building high-quality of instructors and establishing employment guidance ideas form government, enterprises and colleges.
First Principles Calculations of Hydrogen Storage on Calcium-Decorated, Boron-Doped Bilayer Graphene  [PDF]
Xiaojing Zhu
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.611001
Abstract: In this paper, the adsorption and storage of hydrogen on calcium-decorated, boron-doped bilayer graphene was investigated using first principles calculation. The calcium-decorated bilayer graphene was investigated and it was shown that the binding energy of H2 molecule adsorbed on the calcium-decorated bilayer graphene is 0.02 eV and the energy does not belong to reversible usage range of 0.2 - 0.6 eV. Substitutional boron doping can improve the adsorption energy of Ca to bilayer graphene with the empty pz orbital of boron atoms. Our calculations show that calcium atoms can be solidly adsorbed on the interlayer (Ca/B/Graphene) and outerlayer (2Ca/B/Graphene and 3Ca/B/Graphene) of B-doped bilayer graphene. Hydrogen molecule binds with Ca/B/Graphene, 2Ca/B/Graphene and 3Ca/B/Graphene system with an energy that belongs to reversible usage range of 0.2 - 0.6 eV. The overlap between Ca 3d and H2σ orbitals just below the Fermi energy demonstrates the charge transfer between the Ca atom and the H atom and the role of hybridization of the 3d orbita of Ca with the σ orbitals of H2 in efficient adsorption of hydrogen molecules. The charge from hydrogen bonding orbital transfers to empty 3d orbitals of the Ca atom, and then from the 3d orbitals of the Ca atom donated to H2σ* antibonding orbital. Hydrogen moleculars can be adsorbed on the interlayer and outerlayer of Ca-decorated B-doped bilayer graphene.
EFFECT OF CHANGING TEMPERATURE ON ACTIVE CONTROL OF VIBRATING FREQUENCY OF PIEZOELECTRIC CIRCULAR PLATES 1)
变温环境对压电圆板频率主动控制的影响

Zhou Youhe,Zheng Xiaojing,
周又和
,郑晓静

力学学报 , 1998,
Abstract: This paper is to quantitatively study the characteristics of active control of vibrating frequency of a piezothermoelectric circular plate with nonlinear deformation, and the effect of changing temperature of environment and the large amplitude of vibration on the characteristics.The results show that the changing temperature of environment of the plate has influence on the controlled frequency of vibration of the plate by means of piezoelectric voltage. When the controlled voltage is high enough, the effect of vibrating amplitude on the characteristic of voltage-vibrating frequency is not notable.
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