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Modeling Soil Water Retention Curve with a Fractal Method

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Pedosphere 2006年第2期16卷 137-146页

作者： huang guan-Hua ZHANG Ren-Duo huang Quan-Zhong Department of Irrigation and Drainage Chinese-Israeli International Center for Research and Training in Agriculture China Agricultural University Beijing 100083 （China）. Department of Renewable Resources University of Wyoming Laramie WY 82071-3354 （USA）

Many empirical models have been developed to describe the soil water retention curve (SWRC). In this study, a fractal model for SWRC was derived with a specially constructed Menger sponge to describe the fractal scaling behavior of soil; relationships were established among the fractal dimension of SWRC, the fractal dimension of soil mass, and soil texture; and the model was used to estimate SWRC with the estimated results being compared to experimental data for verification. The derived fractal model was in a power-law form, similar to the Brooks-Corey and Campbell empirical functions. Experimental data of particle size distribution (PSD), texture, and soil water retention for 10 soils collected at different places in China were used to estimate the fractal dimension of SWRC and the mass fractal dimension. The fractal dimension of SWRC and the mass fractal dimension were linearly related. Also, both of the fractal dimensions were dependent on soil texture, i.e., clay and sand contents. Expressions were proposed to quantify the relationships. Based on the relationships, four methods were used to determine the fractal dimension of SWRC and the model was applied to estimate soil water content at a wide range of tension values. The estimated results compared well with the measured data having relative errors less than 10% for over 60% of the measurements. Thus, this model, estimating the fractal dimension using soil textural data, offered an alternative for predicting SWRC.

关键词： fractal dimension soil texture soil water retention curve

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Optics-driven drone

Science China(Information Sciences) 2024年第2期67卷 322-324页

作者： Xuelong LI guan huang Zhigang WANG Bin ZHAO School of Artificial Intelligence OPtics and Electro Nics (iOPEN)Northwestern Polytechnical University Shanghai Artificial Intelligence Laboratory

In the field of vicinagearth security, low-altitude flying vehicles such as drones play an indispensable role in aerial remote sensing, intelligent search and rescue, etc. [1]. It can be foreseen that the autonomous and intelligent execution of complex tasks by drones is an inevitable trend for future development.

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Non-Darcian Flow Toward a Finite-Diameter Vertical Well in a Confined Aquifer

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Pedosphere 2008年第3期18卷 288-303页

作者： WEN Zhang huang guan-Hua ZHAN Hong-Bin College o.f Water Conservancy and Civil Engineering China Agricultural University Beijing 100083 （China） Chinese-Israeli International Center for Research and Training in Agriculture Beijing 100083 （China） Department of Geology and Geophysics Texas A＆M University College Station Texas 77843-3115 （USA）

Non-Darcian radial flow toward a finite-diameter, fully penetrating well in a confined aquifer was analyzed on the basis of the Izbash equation with consideration of the wellbore storage effect. We derived semi-analytical solutions of drawdown by using the Boltzmann transform, and obtained approximate analytical solutions of the drawdown at early and late times. MATLAB programs were developed to facilitate computation of the semi-analytical solutions. The turbulence factor v which was directly related to the pumping rate appeared to have negligible influence upon the wellbore well function at early times, but imposed significant influence at intermediate and late times. However, the turbulence factor v imposed non-negligible influence upon the aquifer well function during the entire pumping period, provided that the observation point was not sufficiently close to the wellbore. Sensitivity analysis indicated that the power index n in the Izbash equation had less influence on the type curves at the face of the pumping wellbore, but had much greater influence upon the well function in the aquifer. As the n values increased, the drawdown in the aquifer decreased at early times and increased at late times. The Boltzmann transformation could only be used in an approximate sense for radial non-Darcian flow problems. This approximation would provide accurate solutions at early times, and introduce small but consistent discrepancies at intermediate and late times for the wellbore well function.

关键词： finite-diameter well non-Darcian flow' type curves well function wellbore storage

Gasoline-diesel dual fuel intelligent charge compression ignition(ICCI)combustion:Conceptual model and comparison with other advanced combustion modes

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Science China(Technological Sciences) 2021年第4期64卷 719-728页

作者： LI ZiLong QIAN Yong huang guan ZHAO WenBin ZHANG YaoYuan LU XingCai Key Laboratory for Power Machinery and Engineering of M.O.E. Shanghai Jiao Tong UniversityShanghai 200240China

The internal combustion engines can remain the advantage over competitor technologies for automotive driven,especially the engine efficiency,exceeded 50%while maintaining ultra-low *** this paper,a novel combustion mode characterized by dual high-pressure common-rail direct injection systems,denoted as intelligent charge compression ignition(ICCI)combustion,is proposed to realize high efficiency and clean combustion in wide engine operating ***,commercial gasoline and diesel,which are considered to be complementary in physical and chemical properties,are directly injected into the cylinder by the two independent injection systems,*** this unique design,the in-cylinder air-fuel mixtures can be flexibly adjusted by regulating injection timing and duration of different fuels,consequently obtaining suitable combustion phase and heat release *** ICCI mode can widely run from indicated mean effective pressure 2 bar to 16 bar with an utterly controllable cylinder pressure rising rate,around 50%indicated thermal efficiency and low NOxemissions.A series of experiments were carried out to compare the combustion and emissions of ICCI with other combustion modes(including conventional diesel combustion,reactivity-controlled compression ignition,partially premixed combustion,and gasoline compression ignition).The results show that at the medium engine loads,ICCI mode can reach much high indicated thermal efficiency,especially up to 52%along with extremely low ***,ICCI mode can realize real-time adjustments of in-cylinder mixture stratification and instantaneous combustion mode switch in one cycle at any operating conditions,and has an excellent commercial application prospect for energy conservation and environmental improvement.

关键词： intelligent charge compression ignition(ICCI) dual-fuel direct injection system gasoline diesel high-efficiency clean combustion

CHARACTERIZATION OF MANGANESE PHTHALOCYANINE-Fe_3O_4 NANOPARTICLE COMPOSITE AND ITS ELECTROMAGNETORHEOLOGICAL FLUID

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Journal of Wuhan University of Technology(Materials Science) 1999年第1期14卷 35-40页

作者： huang Jun guan Jianguo ZHAO Suling YUAN Runzhang Wuhan University of Technology Wuhan University of Technology China Fiber Optic Sensing Technol. Centre Wuhan Univ. of Tech. Wuhan 430070 China

Manganese phthalocyanine (MnPc)-Fe3O4 nanoparticles composite was prepared and characterized. The results show that MnPc are completed on the surface of Fe3O4 nanoparticles in the state of single molecule. There is effective composite between MnPc and Fe3O4 nanoparticles which can improve the antioxidization ability of Fe3O4 nanoparticles greatly. The composite was dispersed into chlorinated paraffin oil to form electromag-netorheological (EMR) fluid with high activity, and the EMR properties of this EMR fluid are studied.

关键词： manganese phthaloc yanine nanopar- ticles composite electramagnetorheological fluid

Decline in semen concentration of healthy Chinese adults： evidence from 9357 participants from 2010 to 2015

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Asian Journal of Andrology 2018年第4期20卷 379-384页

作者： Hong-Fang Yuan huang-Fang Shangguan Yi Zheng Tian-Qing Meng Cheng-Liang Xiong huang-Tao guan Family Planning Research Institute Tongji Medical College Huazhong University of Science and Technology Wuhan 430030 China College of Informatics Huazhong Agricultural University Wuhan 430070 China Department of Venereology Wuhan Institute of Dermatology and Venereology Wuhan 430031 China Reproductive Medicine Center Tongji Medical College Huazhong University of Science and Technology Wuhan 430030 China Hubei Province Human Sperm Bank Wuhan 430030 China

The present study aims to analyze sperm concentration trends among young and healthy Chinese adults in Wuhan, Central China, from 2010 to 2015. Semen analysis data from 9357 participants were collected and analyzed using a general linear model and the Cochran-Armitage trend test. A significant decline was observed in sperm concentration （β [standard deviation]： -1.53 [0.16]; P 〈 0.001）. In addition, a decline in sperm density was observed by stratifying student versus nonstudent sperm donors and by analyzing the year of birth or birth year cohort of the participants. Furthermore, the percentage of participants with sperm densities of over 40×10^6 ml^-1 significantly decreased with year. Notably, a dramatic decline in sperm density was recorded over the first 5 years of study.

关键词： healthy men semen concentration sperm donors temporal trends

Non-FDG PET imaging of brain tumors

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Nuclear Science and Techniques 2007年第3期18卷 154-158页

作者： huang Zemin guan Yihui ZUO Chuantao ZHANG Zhengwei XUE Fangping LIN Xiangtong PET Center Huashan Hospital Fudan University Shanghai 200235 China

Due to relatively high uptake of glucose in the brain cortex, the use of FDG PET imaging is greatly limited in brain tumor imaging, especially for low-grade gliomas and some metastatic tumours. More and more tracers with higher specificity were developed lately for brain tumor imaging. There are 3 main types of non-FDG PET tracers: amino acid tracers, choline tracers and nucleic acid tracers. These tracers are now widely applied in many aspects of brain tumor imaging. This article summarized the general use of non-FDG PET in different aspects of brain tumor imaging.

关键词：脑肿瘤正电子发射成像大脑皮层放射疗法

Super-harmonic resonance of gear transmission system under stick-slip vibration in high-speed train

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Journal of Central South University 2017年第3期24卷 726-735页

作者： huang guan-hua XU Si-si ZHANG Wei-hua YANG Cai-jin State Key Laboratory of Traction Power （Southwest Jiaotong University） Chengdu 61003 I China Beijing Haidongqing Electrical and Mechanical Equipment Co. Ltd Beijing 101300 China CRRC Institute Co. Ltd Beiiing 100070 China

This work deals with super-harmonic responses and the stabilities of a gear transmission system of a high-speed train under the stick-slip oscillation of the *** dynamic model of the system is developed with consideration on the factors including the time-varying system stiffness,the transmission error,the tooth backlash and the self-excited excitation of the *** frequency-response equation of the system at super-harmonic resonance is obtained by the multiple scales method,and the stabilities of the system are analyzed using the perturbation *** nonlinear behaviors of the system including multi-valued solutions,jump phenomenon,hardening stiffness are *** effects of the equivalent damping and the loads of the system under the stick-slip oscillation are *** shows that the change of the load can obviously influence the resonance frequency of the system and have little effect on the steady-state response amplitude of the *** damping of the system has a negative effect,opposite to the *** synthetic damping of the system composed of meshing damping and equivalent damping may be less than zero when the wheel-set has a large slippage,and the system loses its stability owing to the Hopf *** results are validated by numerical simulations.

关键词： stick-slip vibration super-harmonic resonance Hopf bifurcation gear transmission system high-speed train

Estimation of the van Genuchten Soil Water Retention Properties from Soil Textural Data

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Pedosphere 2010年第4期20卷 456-465页

作者： B. GHANBARIAN-ALAVIJEH A. LIAGHAT huang guan-Hua M. Th. VAN GENUCHTEN Department of Irrigation and Reclamation Engineering University of Tehran Karaj 31587-77871 （Iran） Department of Earth and Environmental Sciences Wright State University Dayton OH 45435 （USA） Department of Irrigation and Drainage Engineering China Agricultural University Beijing 100083 （China） Department of Mechanical Engineering Federal University of Rio de Janeiro RJ 21945-970 （Brazil）

The van Genuchten (vG) function is often used to describe the soil water retention curve (SWRC) of unsaturated soils and fractured rock. The objective of this study was to develop a method to determine the vG model parameter m from the fractal dimension. We compared two approaches previously proposed by van Genuchten and Lenhard et al. for estimating m from the pore size distribution index of the Brooks and Corey (BC) model. In both approaches we used a relationship between the pore size distribution index of the BC model and the fractal dimension of the SWRC. A dataset containing 75 samples from the UNSODA unsaturated soil hydraulic database was used to evaluate the two approaches. The statistical parameters showed that the approach by Lenhard et al. provided better estimates of the parameter m. Another dataset containing 72 samples from the literature was used to validate Lenhard's approach in which the SWRC fractal dimension was estimated from the clay content. The estimated SWRC of the second dataset was compared with those obtained with the Rosetta model using sand, silt, and clay contents. Root mean square error values of the proposed fractal approach and Rosetta were 0.081 and 0.136, respectively, indicating that the proposed fractal approach performed better than the Rosetta model.

关键词： fractal dimension soil water retention curve van Genuchten parameterization