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A unified model of bidirectional reflectance distribution function for the vegetation canopy

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Science China Earth Sciences 2017年第3期60卷 463-477页

作者： XU XiRu FAN WenJie LI JuCai ZHAO Peng CHEN GaoXing Institute of Remote Sensing and Geographic Information System Peking UniversityBeijing 100871China Beijing Key Laboratory of Spatial Information Integration&Its Applications Beijing 100871China

An accurate and operational bidirectional reflectance distribution function （BDRF） canopy model is the basis of quantitative vegetation remote sensing. The canopy reflectance should be approximated as the sum of the single scattering reflectance arising from the sun, pl, and the multiple scattering reflectance arising from the canopy, fin, as their directional characteristics are dramatically different. Based on the existing BRDF model, we obtain a new analytical expression of ρ1 and ρm in this paper, which is suitable for different illumination conditions and different vegetation canopies. According to the geometrical optic model at the leaf scale, the anisotropy of ρ1 can be ascribed to the geometry of the object, sun and the sensor, multiple scale clumping, and the fraction of direct solar radiation and diffuse sky radiation. Then, we parameterize the area ratios of four components： the sunlit foliage, sunlit ground, shadow foliage and shadow ground based on a Poisson distribution, and develop a new approximate analytical single scattering reflectance model. Assuming G=0.5, a recollision probability theory based scattering model is developed which considers the effects of diffuse sky radiation, scattering inside the canopy and rebounds between the canopy and soil. Validation using ground measurements of maize and black spruce forest proves the reliability of the model.

关键词： Vegetation BRDF unified model Clumping Index Proportion of direct solar radiation and diffuse sky radiation Recollision probability

A unified model with a generalized gauge symmetry and its cosmological implications

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Chinese Physics C 2015年第10期39卷 68-76页

作者： Jong-Ping Hsu Kazuo O.Cottrell Department of Physics University of Massachusetts Dartmouth

A unified model is based on a generalized gauge symmetry with groups [Sg3c]color×（SU2×U1）X[U1b×U11]. It implies that all interactions should preserve conservation laws of baryon number, lepton number, and electric charge, etc. The baryonie U1b, leptonie U11 and color SU3o gauge transformations are generalized to involve nonintegrable phase factors. One has gauge invariant fourth-order equations for massless gauge fields, which leads to linear potentials in the [U1b × U11] and color [SUao] sectors. We discuss possible cosmological implications of the new baryonie gauge field. It can produce a very small constant repulsive force between two baryon galaxies （or between two anti-baryon galaxies）, where the baryon force can overcome the gravitational force at very large distances and leads to an accelerated cosmic expansion. Based on conservation laws in the unified model, we discuss a simple rotating dumbbell universe with equal amounts of matter and anti-matter, which may be pictured as two gigantic rotating clusters of galaxies. Within the gigantic baryonie cluster, a galaxy will have an approximately linearly accelerated expansion due to the effective force of constant density of all baryonie matter. The same expansion happens in the gigantic anti-baryonic cluster. Physical implications of the generalized gauge symmetry on charmonium confining potentials due to new SUac field equations, frequency shift of distant supernovae Ia and their experimental tests are discussed.

关键词： unified model nonintegrable phase factors conservation laws cosmology accelerated expansion

Evaluation of unified model Microphysics in High-resolution NWP Simulations Using Polarimetric Radar Observations

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Advances in Atmospheric Sciences 2018年第7期35卷 771-784页

作者： Marcus JOHNSON Youngsun JUNG Daniel DAWSON Timothy SUPINIE Ming XUE Jongsook PARK Yong-Hee LEE Center for Analysis and Prediction of Storms (CAPS) University of Oklahoma Norman OK 73072 USA School of Meteorology University of Oklahoma Norman OK 73072 USA Purdue University West Lafayette IN 47907 USA Korea Meteorological Administration Seoul 07062 Korea

The UK Met Office unified model（UM） is employed by many weather forecasting agencies around the globe. This model is designed to run across spatial and time scales and known to produce skillful predictions for large-scale weather systems. However, the model has only recently begun running operationally at horizontal grid spacings of ～1.5 km [e.g.,at the UK Met Office and the Korea Meteorological Administration（KMA）]. As its microphysics scheme was originally designed and tuned for large-scale precipitation systems, we investigate the performance of UM microphysics to determine potential inherent biases or weaknesses. Two rainfall cases from the KMA forecasting system are considered in this study： a Changma（quasi-stationary） front, and Typhoon Sanba（2012）. The UM output is compared to polarimetric radar observations in terms of simulated polarimetric radar variables. Results show that the UM generally underpredicts median reflectivity in stratiform rain, producing high reflectivity cores and precipitation gaps between them. This is partially due to the diagnostic rain intercept parameter formulation used in the one-moment microphysics scheme. model drop size is generally both underand overpredicted compared to observations. UM frozen hydrometeors favor generic ice（crystals and snow） rather than graupel, which is reasonable for Changma and typhoon cases. The model performed best with the typhoon case in terms of simulated precipitation coverage.

关键词： unified model microphysics polarimetric radar radar simulator numerical weather prediction

A unified model for the Degradation Kinetics of Pesticides Applied Continually to Soils

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Pedosphere 1997年第1期7卷 9-14页

作者： WANGZONGSHENG LIUDUOSEN 等 InstituteofSoilSocience AcademiaSinicaP.O.Box821Nanjing210008（China） InstituteofSoilSocience Academ

This paper deduces a kinetic model for microbial degradation of pesticides in soils:where x is the concentration of pesticide at time t, so the initial concentration of the pesticide, me the initial number of pesticide-degrading microorganisms, M the carrying capacity for the microorganisms, μ the specific growth rate of the microorganisms, and k the rate constant for the pesticide *** periodic applications of pesticides, this model can be used to continuously describe every degradation curve. Whether a lag phase occurs or not, we can obtain the minimum residue of the pesticide (xe):xe=xdexp(-kMr)/[1-exp(-ker) ]where r is the regular time internals between applications, and xd the dosage of the pesticide.

关键词： microorganisms pesticide degradation unified model

A unified dynamic model for locomotion and manipulation of a snake-like robot based on differential geometry

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Science China(Information Sciences) 2011年第2期54卷 318-333页

作者： WANG ZhiFeng1,3, MA ShuGen1,2, LI Bin1 & WANG YueChao1 1State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China 2Department of Robotics, Ritsumeikan University, Shiga-ken 525-8577, Japan 3Graduate University of Chinese Academy of Sciences, Beijing 100039, China 1. State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang 110016 China3. Graduate University of Chinese Academy of Sciences Beijing 100039 China2. Department of Robotics Ritsumeikan University Shiga-ken 525-8577 Japan

A snake-like robot, whose body is a seried-wound articulated mechanism, can move in various environments. In addition, when one end is fixed on a base, the robot can manipulate objects. A method of dynamic modeling for locomotion and manipulation of the snake-like robot is developed in order to unify the dynamic equations of two states. The transformation from locomotion to manipulation is a mechanism reconfiguration, that is, the robot in locomotion has not a fixed base, but it in manipulation has one. First, a virtual structure method unifies the two states in mechanism (e.g., an embedding in the configuration space); second, the product-of-exponentials formula describes the kinematics; third, the dynamics of locomotion and manipulation are established in a Riemannian manifold; finally, based on the analysis of the dynamic model, the dynamics of manipulation can be directly degenerated from those of locomotion, and this degeneration relation is proved through using the Gauss equations. In the differential geometry formulation, this method realizes the unification of the dynamics of locomotion and manipulation. According to a geometrical point of view, the unified dynamic model for locomotion and manipulation is considered as a submanifold problem endowed with geometric meaning. In addition, the unified model offers an insight into the dynamics of the snake-like robot beyond the dynamic model separately established for locomotion or manipulation.

关键词： snake-like robot dynamics unified model differential geometry locomotion manipulation

A model of unified quantum chromodynamics and Yang-Mills gravity

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Chinese Physics C 2012年第5期36卷 403-409页

作者： HSU Jong-Ping Department of Physics University of Massachusetts Dartmouth North Dartmouth

Based on a generalized Yang-Mills framework, gravitational and strong interactions can be unified in analogy with the unification in the electroweak theory. By gauging T （4） × [SU （3）] color in flat space-time, we have a unified model of chromo-gravity with a new tensor gauge field, which couples universally to all gluons, quarks and anti-quarks. The space-time translational gauge symmetry assures that all wave equations of quarks and gluons reduce to a Hamilton-Jacobi equation with the same ‘effective Riemann metric tensors’ in the geometric-optics （or classical） limit. The emergence of ef f ective metric tensors in the classical limit is essential for the unified model to agree with experiments. The unified model suggests that all gravitational, strong and electroweak interactions appear to be dictated by gauge symmetries in the generalized Yang-Mills framework.

关键词： unified model chromodynamics and gravity generalized Yang-Mills framework effective Riemann metric tensor

Autonomous relative optical navigation based on unified modeling of external systematic errors

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Chinese Journal of Aeronautics 2024年第3期37卷 282-289页

作者： Dayi WANG Bowen SUN Maodeng LI Jiaxing LI Haiyin ZHOU Beijing Institute of Spacecraft System Engineering Beijing 100191China College of Sciences National University of Defense TechnologyChangsha 410073China National Key Laboratory of Space Intelligent Control Beijing Institute of Control EngineeringBeijing 100191China

To solve the problem that external systematic errors of the optical camera cannot be fully estimated due to limited computing resources,a unified dimensionality reduction representation method for the external systematic errors of the optical camera is proposed,and autonomous relative optical navigation is *** camera translational and misalignment errors are converted into a three-dimensional rotation error,whose differential model can be established through specific attitude control and appropriate ***,the rotation error and the relative motion state are jointly estimated in an augmented Kalman filter *** with the traditional method that estimates the camera translational and misalignment errors,the proposed method reduces the computational complexity in that the estimated state dimension is ***,as demonstrated by numerical simulation,the estimation accuracy is improved significantly.

关键词： unified model Systematic errors Optical navigation Observability analysis Calibration

unified modelING OF DESIGN AND MANUFACTURING INFORMATION IN DFM

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UNIFIED MODELING OF DESIGN AND MANUFACTURING INFORMATION IN ...

H_∞ reference tracking control design for a class of nonlinear systems with time-varying delays

2006年中国机械工程学会年会暨中国工程院机械与运载工程学部首届年会

作者： ZHANG Xu*, WANG Tie *Associate Professor, School of Mechanical and Vehicular Engineering, Beijing Institute of Technology, Beijing, 100081, China, Professor, College of Mechanical Engineering, Taiyuan University of Technology, Taiyuan, 030024, China

DFM method can only be realized with the help of complete, unified modeling of product requirements, functionalities, assembly relations, shape, dimensions and tolerance, and manufacturing requirement

关键词： DFM unified model function model form feature feature-based design feature mapping.

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Frontiers of Information Technology & Electronic Engineering 2015年第9期16卷 759-768页

作者： Mei-qin LIU Hai-yang CHEN Sen-lin ZHANG State Key Laboratory of Industrial Control Technology Zhejiang University College of Electrical Engineering Zhejiang University

This paper investigates the H∞ trajectory tracking control for a class of nonlinear systems with time- varying delays by virtue of Lyapunov-Krasovskii stability theory and the linear matrix inequality （LMI） technique. A unified model consisting of a linear delayed dynamic system and a bounded static nonlinear operator is introduced, which covers most of the nonlinear systems with bounded nonlinear terms, such as the one-link robotic manipulator, chaotic systems, complex networks, the continuous stirred tank reactor （CSTR）, and the standard genetic regulatory network （SCRN）. First, the definition of the tracking control is given. Second, the H∞ performance analysis of the closed-loop system including this unified model, reference model, and state feedback controller is presented. Then criteria on the tracking controller design are derived in terms of LMIs such that the output of the closed-loop system tracks the given reference signal in the H∞ sense. The reference model adopted here is modified to be more flexible. A scaling factor is introduced to deal with the disturbance such that the control precision is improved. Finally, a CSTR system is provided to demonstrate the effectiveness of the established control laws.

关键词： H∞ reference tracking Nonlinear system State feedback control Time-varying delays unified model