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A novel method of systematic error compensation for a position and orientation system

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Progress in Natural Science:Materials International 2008年第8期18卷 953-963页

作者： Xiuxiao Yuan* school of Remote Sensing and Information Engineering, wuhan university, wuhan 430079, china school of Remote Sensing and Information Engineering Wuhan University Wuhan 430079 China

A novel method is introduced for self-calibration and elimination of systematic errors for a position and orientation system (POS). The method uses a combined bundle block adjustment with POS data (named the POS-supported bundle block adjustment) without a calibration field. On the basis of delivering strict observation equations for POS data, the specific scheme of compensating the translation and drift systematic errors in a POS is given, and a prototype system WuCAPS is developed. The effects of eliminating POS systematic errors using the POS-supported bundle block adjustment for different ground control conditions are tested using two sets of actual aerial photos. The first set was taken over a flat region in the suburbs of the city of Yingkou in china and tested at a scale of 1:2500. The second set was taken over a high mountainous region in the desert region of Xinjiang in china and tested at a scale of 1:32,000. The empirical results verified that the POS systematic errors can be completely eliminated and the photo elements of exterior orientation obtained by the POS-supported bundle block adjustment can satisfy the requirements of aerial photogrammetric topographic mapping when four full ground control points (GCPs) are emplaced in the corners of the adjustment block for large-scale images of flat regions, but only one full GCP emplaced in the center of the adjustment block is needed for medium-small scale images of mountainous regions. This not only demonstrates the validity of the established mathematical model and the feasibility of the method proposed in this paper, but also avoids the use of a special calibration field. Therefore, it can simplify the existing POS operation rules and dramatically save on practical application costs, laying the theoretical foundation for widespread use of POS.

关键词： Position and orientation system (POS) Systematic error POS-supported bundle block adjustment Self-calibration Accuracy

A PRICE-SETTING NEWSVENDOR MODEL UNDER CVAR DECISION CRITERION WITH EMERGENCY PROCUREMENT

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Journal of Systems Science and Systems Engineering 2010年第1期19卷 85-104页

作者： Minghui XU school of Economics and Management,wuhan university,wuhan 430072,china school of Economics and Management Wuhan University Wuhan China

In this paper, we consider a newsvendor model in which a risk-averse manager faces a stochastic price-dependent demand in either an additive or a multiplicative form. An emergency purchase option is allowed after the realization of demand to satisfy the units that are short. By adopting Conditional value-at-risk （CVaR） as the decision criterion, we aim to investigate the optimal pricing and ordering decisions, and the effects of parameter changes in such a setting. We provide sufficient conditions for the uniqueness of the optimal policy for both demand models. We perforl~, comparative statics analysis to show how the optimal pricing and ordering decision behaves when changing parameters. We also compare our results with those of the newsvendor with a general utility function and with CVaR criterion under lost sales assumption. Our key results include：（i） For both demand models, the optimal selling price is decreasing in risk aversion. Hence, the optimal price of a risk-averse newsvendor is not greater than the optimal price of a risk-neutral newsvendor. （it） In contrary to the lost sales case, for the multiplicative demand model, the optimal order quantity may not be monotonic in risk aversion. Consequently, the optimal risk-averse order quantity may be lower or higher than the optimal risk- neutral counterpart. （iii） For the additive model, the optimal order quantity is strictly increasing in the emergency purchase price, while for the multiplicative model the optimal order quantity has no such a monotonic property. Some numerical examples are conducted to verify our claims and gain more insights about the risk-averse decision-making behaviors.

关键词： Newsvendor model inventory pricing risk aversion conditional value-at-risk

Numerical study of the auroral particle transport in the polar upper atmosphere

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Science china(Technological Sciences) 2008年第10期51卷 1759-1771页

作者： CAI HongTao1,2, MA ShuYing1,2 & PU ZuYin3 1 school of Electronic Information, wuhan university, wuhan 430079, china 2 Key Laboratory of Geospace Environment and Geodesy, Ministry of Education of PRC, wuhan 430079, china 3 school of Earth and Space Sciences, Peking university, Beijing 100871, china 1. school of Electronic Information Wuhan University Wuhan 430079 China 2. Key Laboratory of Geospace Environment and Geodesy Ministry of Education of PRC Wuhan 430079 China 3. school of Earth and Space Sciences Peking University Beijing 100871 China

Starting from the Boltzmann equation and with some reasonable assumptions, a one-dimensional transport equation of charged energetic particles is derived by taking account of major interactions with neutral species in the upper atmosphere, including the processes of elastic scattering, the excitation, the ionization and the secondary electron production. The transport equation is numerically solved, for a simplified atmosphere consisting only of nitrogen molecules (N2), to obtain the variations of incident electron fluxes as a function of altitude, energy and pitch angle. The model results can describe fairly the transport characteristics of pre-cipitating auroral electron spectra in the polar upper atmosphere; meanwhile the N2 ionization rates calculated from the modeled differential flux spectra also exhibit good agreements with existing empirical models in terms of several key parameters. Taking the energy flux spectra of precipitating electrons observed by FAST satellite flying over EISCAT site on May 15, 1997 as model inputs, the model-calculated ionization rate profile of neutral atmosphere consists reasonably with that recon-structed from electron density measurements by the radar.

关键词： aurora particle precipitation polar upper atmosphere electron transport equation numerical simulation

Indeterminate direction relation model based on fuzzy description framework

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Science china(Technological Sciences) 2008年第S1期51卷 72-80页

作者： LIU YaoLin1,HE JianHua1,YU Yan2 & TANG XinMing3 1 school of Resource and Environment Science,wuhan university,wuhan 430079,china 2 school of Resource and Environment Engineer,wuhan university of Technology,wuhan 430070,china 3 Chinese Academy of Surveying and Mapping,Beijing 10083,china school of Resource and Environment Science Wuhan University Wuhan 430079 China school of Resource and Environment Engineer Wuhan University of Technology Wuhan 430070 China Chinese Academy of Surveying and Mapping Beijing 10083 China

The indetermination of direction relation is a hot topic for fuzzy GIS researchers. The existing models only study the effects of indetermination of spatial objects,but ignore the uncertainty of direction reference framework. In this paper,first a for-malized representation model of indeterminate spatial objects is designed based on quadruple (x,y,A,μ),then a fuzzy direction reference framework is constructed by revising the cone method,in which the partitions of direction tiles are smooth and continuous,and two neighboring sections are overlapped in the transitional zones with fuzzy method. Grounded on these,a fuzzy description model for indeterminate direction relation is proposed in which the uncertainty of all three parts (source object,reference object and reference frame) is taken into account simultaneously. In the end,case studies are implemented to test the rationality and validity of the model.

关键词： direction relation fuzzy description framework fuzzy representation model uncertainty

Fuzzy entropy image segmentation based on particle swarm optimization

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Progress in Natural Science:Materials International 2008年第9期18卷 1167-1171页

作者： Linyi Li a, Deren Li b, a school of Remote Sensing and Information Engineering, wuhan university, wuhan 430079, china b State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, wuhan university, wuhan 430079, china school of Remote Sensing and Information Engineering Wuhan University Wuhan 430079 China State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan 430079 China

Particle swarm optimization is a stochastic global optimization algorithm that is based on swarm *** of its excellent performance, particle swarm optimization is introduced into fuzzy entropy image segmentation to select the optimal fuzzy parameter combination and fuzzy threshold *** this study, the particles in the swarm are constructed and the swarm search strategy is proposed to meet the needs of the segmentation *** fuzzy entropy image segmentation based on particle swarm opti-mization is implemented and the proposed method obtains satisfactory results in the segmentation *** with the exhaustive search method, particle swarm optimization can give the same optimal fuzzy parameter combination and fuzzy threshold while needing less search time in the segmentation experiments and also has good search stability in the repeated ***, fuzzy entropy image segmentation based on particle swarm optimization is an eficient and promising segmentation method.

关键词： Image segmentation Fuzzy entropy Particle swarm optimization Fuzzy parameter combinations Fuzzy threshold

On the Symmetry Classes of Functions

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wuhan university Journal of Natural Sciences 2005年第5期10卷 813-816页

作者： ZHU Ping~1,2, FAN Yun~3 1. school of Mathematics and Statistics, wuhan university, wuhan 430072, Hubei, china 2. school of Science, Beijing university of Posts and Telecommunications, Beijing 100876, china 3. school of Mathematics and Statistics, Huazhong Normal university, wuhan 430079, Hubei, china wuhan university School of Mathematics and Statistics Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Beijing university of Posts and Telecommunications School of Science Beijing China (GRID:grid.31880.32) Huazhong Normal university School of Mathematics and Statistics Wuhan Hubei China (GRID:grid.411407.7) (ISNI:***)

Let R be an integral domain of characteristic zero such that the corresponding group rings have block decompositions. We first prove that the submodule consisting of all the R-valued ξi-symmetric functions of several variables is a symmetry class, where ξi is any block character. Then we present a relationship among certain operators introduced for block character. Then we present a relationship among certain operators introduced for block characters. As a consequence, we obtain a decomposition of an arbitrary R-valued function of several variables. Finally, we describe the symmetry property of such summands and determine all the symmetry classes.

关键词： symmetry class strict symmetry class blockcharacter ξi-symmetric function block idempotent

A theorem of Fong's type for graded algebras

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Science china Mathematics 2005年第5期48卷 577-582页

作者： FAN Yun & ZHU Ping school of Mathematics and Statistics, Central china Normal university, wuhan 430079, china school of Mathematical Science, Nankai university, Tianjin 300071, china 1. school of Mathematics and Statistics Central China Normal University 430079 Wuhan China 2. school of Mathematical Science Nankai University 300071 Tianjin China

Let G be a finite p-solvable group and k be an algebraic closed field of characteristic p. It is proved that any projective indecomposable module of a G-graded k-algebra is an induced module of a module of the subalgebra graded by a Hall p′-subgroup. A necessary and sufficient condition for the indecomposability of an induced module from a Hall p′-subgroup is obtained.

关键词： group graded algebra indecomposable induced module primitive idempotent.

Multi-resolution representation of digital terrain models with terrain features preservation

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Science china(Technological Sciences) 2008年第S1期51卷 145-154页

作者： LI QingQuan1,WANG Zhi1,2 & YANG BiSheng1 1 State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,wuhan university,wuhan 430079,china 2 school of Remote Sensing and Information Engineering,wuhan university,wuhan 430079,china 1. State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan 430079 China2. School of Remote Sensing and Information Engineering Wuhan University Wuhan 430079 China

multi-resolution TIN model is an important issue in the contexts of visu-alization,virtual reality (VR),and geographic information systems (GIS). This paper proposes a new method for constructing multi-resolution TIN models with multi-scale topographic features preservation. The proposed method is driven by a half-edge collapse operation in a greedy framework and employs a new quadric error metric to efficiently measure geometric errors. We define topographic features in a multi-scale manner using a center-surround operator on Gaussian-weighted mean curvatures. Experimental results demonstrate that the proposed method performs better than previous methods in terms of topographic features preservation,and is able to achieve multi-resolution TIN models with a higher accuracy.

关键词： digital terrain models level of detail differential-geometry quadric error metrics topographic feature

Land use data generalization indices considering scale and land use pattern effects

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Science china Earth Sciences 2011年第5期54卷 694-702页

作者： LIU YaoLin1,2,JIAO LiMin1,2 & LIU YanFang1,2 1 school of Resource and Environmental Sciences,wuhan university,wuhan 430079,china 2 Key Laboratory of Geographic Information System,Ministry of Education,wuhan university,wuhan 430079,china 1. school of Resource and Environmental Sciences Wuhan University Wuhan 430079 China2. Key Laboratory of Geographic Information System Ministry of Education Wuhan University Wuhan 430079 China

Land use generalization indices are critical for producing normative multi-scale land use databases and maps,but there is still not a national criterion for these indices in *** studies on land use data generalization indices often neglect macroindices such as area proportion of land use types and map load,and also ignore landscape effects on land use generalization *** we constructed an index system of land use data generalization from macro-and micro-perspectives,and examined scale and landscape effects on land use data generalization indices based on the countrywide multi-scale land use data *** formulated relationships between land use data generalization indices and both scale and land use pattern *** defined thresholds of land use data generalization indices on scales of 1:50000,1:100000,1:250000,and 1:*** verified our methodology and index thresholds through generalizing a county land use database.

关键词： land use database land use database generalization generalization indices land use pattern landscape metrics