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Search Results: 1 - 10 of 28038 matches for " Guoqing Hu "
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Discussion of Direct Numerical Simulation Method for Supercritical Carbon Dioxide Jet Flow  [PDF]
Hui Gao, Guoqing Hu
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.410171

A kind of direct numerical simulation method suitable for supercritical carbon dioxide jet flow has been discussed in this paper. The form of dimensionless nonconservative compressible Navier-Stokes equations in a two-dimensional cartesian coordinate system is derived in detail. High accurate finite difference compact schemes based on non-uniform grid system are introduced to solve the equations. The simulation results of the three vortex pairing phenomenon of plane mixing layer and a compressible axisymmetric jet flow field show that the discussed numerical simulation method is feasible to calculate the supercritical carbon dioxide jet fluid. And it is found that the difficulties of splitting the convective terms in conservation Navier-Stokes equations, which are brought by the supercritical carbon dioxide fluid pressure state equation, can be avoided by solving the nonconservative compressible Navier-Stokes equations.

Modeling, Simulation and Design of a Laser-type Pressure Sensor
YanQing Hu,GuoQing Hu
Journal of Computers , 2011, DOI: 10.4304/jcp.6.12.2726-2733
Abstract: In the field of photoelectric sensing and measurement, laser triangulation is a superior and widely used technology due to its advantages of high accuracy, rapidity, and non-contact. This paper first applied it to the measurement of pressure, and proposed and designed a laser-type pressure sensor. The sensor measured the center deflection of the circular pressure-sensitive diaphragm using the laser triangulation, then determined the pressure on the diaphragm according to the small-deflection theory. In the aspect of optical system, the sensor used the principle of lens imaging of magnification and constant focus combining with high-resolution photodetector, which further improved the system accuracy effectively. First the paper created the mathematical model of the laser triangulation in view of the high accuracy, small size requirements. Afterward determined the parameters of the diaphragm in light of the linear range and measurement accuracy of the pressure, and did the finite element analysis of the diaphragm using ANSYS. The analysis demonstrates that within the pressure range, meeting the small-deflection theory, the relationship between the pressure and the deflection is nearly linear. The minimum pressure of the sensors designed is 50Pa, the pressure range is 1.4614MPa, and the maximum relative nonlinearity error of the diaphragm is 1.273%. This simulation design provides a forceful and important basis for the realization of the sensor.
A step forward for understanding the morbidity burden in Guinea: a national descriptive study
Keita Mamady, Guoqing Hu
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-436
Abstract: A retrospective descriptive study was designed to present the morbidity burden of Guinea. Morbidity data were extracted from the National Health Statistics Report of Guinea of 2008. The data are collected based on a pyramid of facilities which includes two national hospitals (teaching hospitals), seven regional hospitals, 26 prefectural hospitals, 8 communal medical centers, 390 health centers, and 628 health posts. Morbidity rates were calculated to measure the burden of non-fatal diseases. The contributions of the 10 leading diseases were presented by sex and age group.In 2008, a total of 3,936,599 cases occurred. The morbidity rate for males was higher than for females, 461 versus 332 per 1,000 population. Malaria, respiratory infections, diarrheal diseases, helminthiases, and malnutrition ranked in the first 5 places and accounted for 74% of the total burden, respectively having a rate of 148, 64, 33, 32, and 14 per 1,000 population. The elderly aged 65+ had the highest morbidity rate (611 per 1,000 population) followed by working-age population (458 per 1,000 population) and children (396 per 1,000 population) while the working-age population aged 25-64 contributed the largest part (39%) to total cases. The sex- and age-specific spectrum of morbidity burden showed a similar profile except for small variations.Guinea has its unique morbidity burden. The ten leading causes of morbidity burden, especially for malaria, respiratory infections, diarrheal diseases, helminthiases, and malnutrition, need to be prioritized in Guinea.A consistent description of the burden of diseases and injuries, and the risk factors associated with them, is an important input to health decision-making and planning processes [1]. The Global Burden of Disease (GBD) Study that was initiated in the early 1990s [2-4] provides a comprehensive assessment of the disease burden for all regions of the world, and yields important evidence for priority setting in health policy and research, and for
Comparing road traffic mortality rates from police-reported data and death registration data in China
Hu,Guoqing; Baker,Timothy; Baker,Susan P;
Bulletin of the World Health Organization , 2011, DOI: 10.2471/BLT.10.080317
Abstract: objective: to compare death rates from road traffic injuries in china in 2002-2007 when derived from police-reported data versus death registration data. methods: in china, police-recorded data are obtained from police records by means of a standardized, closed-ended data collection form; these data are published in the china statistical yearbook of communication and transportation. official death registration data, on the other hand, are obtained from death certificates completed by physicians and are published in the china health statistics yearbook. we searched both sources for data on road traffic deaths in 2002-2007, used the χ2 test to compare the mortality rates obtained, and performed linear regression to look for statistically significant trends in road traffic mortality over the period. findings: for 2002-2007, the rate of death from road traffic injuries based on death registration data was about twice as high as the rate reported by the police. linear regression showed a significant decrease of 27% (95% confidence interval, ci: 35-19) in the death rate over the period according to police sources but no significant change according to death registration data. conclusion: the widely-cited recent drop in road traffic mortality in china, based on police-reported data, may not reflect a genuine decrease. the quality of the data obtained from police reports, which drives decision-making by the government of china and international organizations, needs to be investigated, monitored and improved.
A SiC high-temperature Pressure Sensor Operating in Severe Condition
Haojie Lv,Huiyong Yu,Guoqing Hu
TELKOMNIKA : Indonesian Journal of Electrical Engineering , 2012, DOI: 10.11591/telkomnika.v10i8.1692
Abstract: The tranditional MEMS pressure sensor based on Silicon (Si) material has not been suitable for operating in severe condition such as high-temperature (>500°C). However, as an alternative material, Silicon Carbide (SiC) can be used in hash environment due to its unique properties. Hence this paper presents a touch mode capacitive pressure sensor with double-notches structure, which employs a special SiC-AlN-SiC sandwich structure to achieve high-accuracy pressure measurement in high-temperature environment. In order to get the relation of capacitance and external pressure, the large deflection theory is applied in simulation analysis of the diaphragm deformation. At the same time, the sandwich structure and technical process of the sensor are studied in the paper. The results showed that the sensor has excellent high-temperature performance due to application of SiC and AlN materials, and the sensor has higher sensitivity and longer linear range than traditional single-cavity structure. Consequently, the sensor can be applied to accuracy pressure measuremet in high-temperature and harsh environment.
Fatality from Road Traffic Accident in Guinea: A Retrospective Descriptive Analysis  [PDF]
Keita Mamady, Bin Zou, Sylla Mafoule, Jiabi Qin, Keita Hawa, Keita Fodé Lamine, Guoqing Hu
Open Journal of Preventive Medicine (OJPM) , 2014, DOI: 10.4236/ojpm.2014.411091
Abstract: Objectives: Causes and risk factors that result in fatal road traffic accident have not been described at the national level in Guinea yet. The goal of this study is to explore the causes and risk factors related to fatal road traffic accident, identified most vulnerable road users, and inform the road traffic prevention policy in Guinea. Methods: We made a retrospective descriptive analysis based on national fatal road traffic accident data from the Department of Health Information at the Guinean Ministry of Health for year 2011. Results: In 2011, road traffic accident was responsible for an aggregate number of 1655 deaths with an overall death rate of 15.3 per 100,000 population. Male experienced more than twice the risk of death from road traffic accidents (21.9 deaths per 100,000 population) compared with female (9.0 deaths per 100,000 population). While taking the population as a whole, the highest death rate was found among the middle aged in 35 - 49 age group accounting for (29.7 deaths per 100,000 population), followed successively by young adults age group 25 - 34 years (24.6 deaths per 100,000 population), and the middle aged in 50 - 64 age group (22.9 deaths per 100,000 population). Principally, occupants, motorcyclists and pedestrians sustained considerable burden of deaths respectively (9.2; 2.9; 2.2 per 100,000 population). In re-gional setting, the highest death rate was found in Upper Guinea (19.5 per 100,000 population), followed by Forest Guinea (18.7 per 100,000 population) and Middle Guinea (16.8 per 100,000 population). A large proportion of male was killed as motorcyclist than female while high per-centage of female died as occupant than male for all age group. The regional distribution showed that when a remarkable number of occupant death were observed in Upper and Forest Guinea, more people died as pedestrian and pedal cyclist in Conakry. Conclusions: This study demonstrated that most of the deaths were among occupants, motorcyclists and pedestrians, and the productive workforce aged 25 - 49 years. It was found that majority of the deaths happened in Upper Guinea followed by Forest Guinea. Improvement of roads design, strict enforcement of road safety laws and raising the awareness of general public about the causes and risks factors of road traffic accident through various channels are highly required which will promote economic growth in the local communities and then help people escape the poverty trap.
Effects of Magnetic Fluid Hyperthermia Induced by An Alternative Magnetic Field on Human Carcinoma A549 Cell in vitro
Guoqing WANG,Hu LI,Runlei HU,Xianfu KE
Chinese Journal of Lung Cancer , 2011,
Abstract: Background and objective Magnetic fluid hyperthermia (MFH) is a method of heat therapy using nanometer techniques and hyperthermia. It has the advantage of high specificity of targeting. The aim of this study is to detect the effects of MFH induced by an alternating magnetic field on human being carcinoma A549 cells in vitro. Methods A human adenocarcinoma cell line A549 was cultured with various concentrations of ferroferric oxide (Fe3O4) magnetic fluid (1.5-6.0) mg/mL and exposed to an alternative magnetic field (AMF) for 30 min. And then the optical density (OD) of viable cell, cytotocixity index, growth curve of cells, morphologic changes of cell, cell cycle and aposptosis were measured. Results The proliferation of the A549 cells were remarkably inhibited, the OD value of viable cells decreased and cytotoxity index (CI) increased; Apoptosis of the A549 cells were observed to have cell shrinkage, chromatin condensation, margination, unclear fragmentation and intact cell membrane by light and electron microscopy; The cells were inhibited in the stage S. Conclusion MFH induced by AMF could inhibit the proliferation, which promotes apoptosis and arrest at S stage of the A549 cells.
Effects of ecological factors on plant communities of Ziwuling Mountain, Shaanxi Province, China

Li Guoqing,Wang Xiaoan,Guo Hu,Zhu Zhihong,

生态学报 , 2008,
Abstract: This paper explores the relationships between environmental factors and community patterns. In 60 plots in the Malan Forest Region of the Loess Plateau, 17 variables were used as indicators of spatial position, soil and topography characteristics. Plant community types were analyzed by TWINSPAN (Two-way Indicator Species Analysis). Significant environmental factors were selected by forward selection and Monte Carlo tests. The relationship between communities and environmental factors was identified by DCCA (Detrended Canonical Correspondence Analysis). Partial CCA (Canonical Correspondence Analysis) partitioned observed compositional variation into components explained by environment, locality and covariation between them. The results showed that: (1) the plant communities can be divided into 13 types including 4 different successional stages. (2) Salt and alkali-hydrolyzable nitrogen are the significant factors related to plant community distribution at early stage. Elevation and humus thickness are the significant factors in the transitional stage. Elevation, slope, aspect, thickness of forest floor, humus thickness and pH are the significant factors for the sub-climax stage. Elevation, slope, aspect, pH and available phosphorus are the significant factors for the climax stage. (3) The ecological characters and the distribution patterns of plant communities in different successional stages are consistent with environmental gradients. (4) As succession proceeds, the impact of environmental conditions on plant communities increases, while the total influence of spatial location, and the interaction between the spatial location and environmental factors decrease.

QI Guoqing,HU Liwen,

岩石力学与工程学报 , 2006,
Abstract: The slope protection with vegetation is to stabilize slope and protect slope surfaces according to the mechanisms of conservation of both moisture and soil with vegetation.Research shows that the mechanisms of the slope protection with vegetation include that (1) root system of woody plant can anchor rock and soil slope bodies; (2) root system of herbaceous plant has reinforcement action for rock and soil slope bodies;and (3) vegetation can prevent the erosion caused by slope surfaces.The chief characters of the slope protection with vegetation can be described as follows:(1) the effort of the slope protection with vegetation is very weak in initial stage,but will increase as vegetation growing;(2) the action range and effort of root system is limited;and (3) relatively stable slope is demanded for the slope protection with vegetation.Based on these,environmental compatibility and routine of the slope protection with vegetation are discussed.Combining the technologies of traditional slope protection and slope protection with vegetation,the respective merit of each method can be displayed,with this method slope stability can be guaranteed,reinforcement measure is durably effective,and immediate revegetation on the slope surfaces and the ecological environment protection are realized.
Ground States for a Class of Nonlinear Schrodinger-Poisson Systems with Positive Potential  [PDF]
Guoqing Zhang, Xue Chen
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.61004
Abstract: Based on Nehari manifold, Schwarz symmetric methods and critical point theory, we prove the existence of positive radial ground states for a class of Schrodinger-Poisson systems in \"\" , which doesn’t require any symmetry assumptions on all potentials. In particular, the positive potential is interesting in physical applications.
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