检索结果-南通市图书馆

An interactive rendering system using hierarchical data structure for earth-scale clouds

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(information Sciences) 2010年第5期53卷 920-931页

作者： DOBASHI Yoshinori YAMAMOTO Tsuyoshi NISHITA Tomoyuki graduate school of information Science and Technology Hokkaido University graduate school of Frontier Science The University of Tokyo

This paper presents an interactive system for realistic visualization of earth-scale clouds. Realistic images can be generated at interactive frame rates while the viewpoint and the sunlight directions can be changed interactively. The realistic display of earth-scale clouds requires us to render large volume data representing the density distribution of the clouds. However, this is generally time-consuming and it is difficult to achieve the interactive performance, especially when the sunlight direction can be changed. To address this, our system precomputes the integrated intensities and opacities of clouds for various viewing and sunlight directions. This idea is combined with a novel hierarchical data structure for further acceleration. The photorealism of the final image is improved by taking into account the atmospheric effects and shadows of clouds on the earth. We demonstrate the usefulness of our system by an application to a space flight simulation.

关键词： computer graphics efficient rendering large-scale clouds level of detail light scattering

STRUCTURAL DECOMPOSITION ANALYSIS ON CHINA'S ENERGY INTENSITY CHANGE FOR 1987-2005

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of systems Science & Complexity 2012年第1期25卷 156-166页

作者： Yan XIA Cuihong YANG Xikang CHEN Institute of systems Science Academy of Mathematics and Systems ScienceChinese Academy of Sciences graduate school of the Chinese Academy of Sciences

There has been considerable debate about the major factors responsible for the dramatic decline of China＇s energy intensity in the 1980s and 1990s. However, few detailed analysis has been done to explain the fluctuation in energy intensity during 2002-005. In this paper, we use the structural decomposition analysis （SDA） to decompose energy intensity into five determining factors： Energy input coefficient, technology coefficient （Leontief inverse coefficient）, final demands structure by product, final demands by category and final energy consumption coefficient. We then further decompose two coefficients, energy input coefficient and technology coefficient, into structure and real coefficient. Empirical study is carried out based on the energy-input-output tables from 1987 to 2005 in 2000 constant price. The results show that between 1987 and 2002, energy input structure accounts for most of the decline in energy intensity. However, the input structure and final demands structure by product explain the increase of the energy intensity between 2002 and 2005.

关键词： Energy intensity input-output technology RAS method structural decomposition anal ysis

B-SPLINE PATCHES AND TRANSFINITE INTERPOLATION METHOD FOR PDE CONTROLLED SIMULATION

在线全文

学校读者我要写书评

暂无评论

Journal of systems Science & Complexity 2012年第2期25卷 348-361页

作者： Yuanjie LIU Hongbo LI Institute of systems Science Academy of Mathematics and Systems ScienceChinese Academy of Sciences graduate school of the Chinese Academy of Sciences

This paper is to discuss an approach which combines B-spline patches and transfinite interpolation to establish a linear algebraic system for solving partial differential equations and modify the WEB-spline method developed by Klaus Hollig to derive this new idea. First of all, the authors replace the R-function method with transfinite interpolation to build a function which vanishes on boundaries. Secondly, the authors simulate the partial differential equation by directly applying differential opera- tors to basis functions, which is similar to the RBF method rather than Hollig＇s method. These new strategies then make the constructing of bases and the linear system much more straightforward. And as the interpolation is brought in, the design of schemes for solving practical PDEs can be more flexi- ble. This new method is easy to carry out and suitable for simulations in the fields such as graphics to achieve rapid rendering. Especially when the specified much faster than WEB-spline method. precision is not very high, this method performs

关键词： B-spline representation finite element method RBF transfinite interpolation WEB-spline.

Olive Leaf Disease Detection via Wavelet Transform and Feature Fusion of Pre-Trained Deep Learning Models

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第3期78卷 3431-3448页

作者： Mahmood A.Mahmood Khalaf Alsalem Department of information systems College of Computer and Information SciencesJouf UniversitySakakahKingdom of Saudi Arabia Department of information systems and Technology Faculty of Graduate Studies and ResearchCairo UniversityGizaEgypt

Olive trees are susceptible to a variety of diseases that can cause significant crop damage and economic *** detection of these diseases is essential for effective *** propose a novel transformed wavelet,feature-fused,pre-trained deep learning model for detecting olive leaf *** proposed model combines wavelet transforms with pre-trained deep-learning models to extract discriminative features from olive leaf *** model has four main phases:preprocessing using data augmentation,three-level wavelet transformation,learning using pre-trained deep learning models,and a fused deep learning *** the preprocessing phase,the image dataset is augmented using techniques such as resizing,rescaling,flipping,rotation,zooming,and *** wavelet transformation,the augmented images are decomposed into three frequency *** pre-trained deep learning models,EfficientNet-B7,DenseNet-201,and ResNet-152-V2,are used in the learning *** models were trained using the approximate images of the third-level sub-band of the wavelet *** the fused phase,the fused model consists of a merge layer,three dense layers,and two dropout *** proposed model was evaluated using a dataset of images of healthy and infected olive *** achieved an accuracy of 99.72%in the diagnosis of olive leaf diseases,which exceeds the accuracy of other methods reported in the *** finding suggests that our proposed method is a promising tool for the early detection of olive leaf diseases.

关键词： Olive leaf diseases wavelet transform deep learning feature fusion

Improved algorithms to plan missions for agile earth observation satellites

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of systems Engineering and Electronics 2014年第5期25卷 811-821页

作者： Huicheng Hao Wei Jiang Yijun Li Research Center of information Management and information systems Harbin Institute of Technology school of Engineering Northeast Agricultural University

This study concentrates of the new generation of the agile （AEOS）. AEOS is a key study object on management problems earth observation satellite in many countries because of its many advantages over non-agile satellites. Hence, the mission planning and scheduling of AEOS is a popular research problem. This research investigates AEOS characteristics and establishes a mission planning model based on the working principle and constraints of AEOS as per analysis. To solve the scheduling issue of AEOS, several improved algorithms are developed. Simulation results suggest that these algorithms are effective.

关键词： mission planning immune clone algorithm hybrid genetic algorithm (EA) improved ant colony algorithm general particle swarm optimization (PSO) agile earth observation satellite (AEOS).

Analyzing the Value of Location information for Four Taxi Dispatching Modes

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2005年第Z1期10卷 844-851页

作者： XU Zhengchuan JIN Huiliang LING Hong Department of information Management and information systems School of ManagementFudan University Shanghai 200433 China Department of Information Management and Information Systems School of ManagementFudan University Shanghai 200433 China Department of Information Management and Information Systems School of ManagementFudan University Shanghai 200433 China

Location-based service (LBS) is often quoted as one of the killer applications of mobile commerce. The LBS, especially the GPS dispatching system, is often adopted by taxi operators for fleet management, but there is no theoretical analysis on the real value of location information for dispatching services. This paper presents four types of dispatching modes and how location information is obtained and used to support dispatching services. Then the Pros and Cons of different taxi dispatching modes were compared. It is concluded that different mode fits different situations, no one overwhelms all situation, even if the GPS-based dispatching mode. The value of the GPS-based dispatching service then was further analyzed through the case study of DaZhong Company in Shanghai, China. The results show that the use of the up-to-date GPS technology radically changes the traditional approaches to taxi dispatching and enables companies to enhance customers'satisfaction.

关键词： mobile commerce location-based service (LBS) taxi dispatching

Accurate measurement and influence on device reliability of defect density of a light-emitting diode

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2013年第10期22卷 412-416页

作者：郭祖强钱可元 Key Laboratory of information Science and Technology Graduate School of Tsinghua University at Shenzhen

A method of accurately measuring the defect density of a high-power light-emitting diode （LED） is proposed. The method is based on measuring the number of emitting photons in the magnitude of 105 under the injection current as weak as nA and calculating the non-radiative recombination coefficient which is related to defect density. Defect density is obtained with the self-developed measurement system, and it is demonstrated that defect density has an important influence on LED optical properties like luminous flux and internal quantum efficiency （IQE）. At the same time, a batch of GaN-based LEDs with the chip size of 1 minx 1 mm are selected to conduct the accelerated aging tests lasting for 1000 hours. The results show that defect density exhibits a greater variation and is more sensitive to LED reliability than luminous flux during aging tests. Based on these results, it is concluded that for the GaN-based LED with a chip size of 1 mm ~ I mm, if its defect density is over 1017/cm3, the LED device performance suffers a serious deterioration, and finally fails.

关键词： accurate measurement defect density LED reliability

Analysis of average capacity for free-space optical links with pointing errors over gamma-gamma turbulence channels

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2010年第6期8卷 537-540页

作者：刘超姚勇孙云旭赵新辉 Department of Electronic and information Engineering Shenzhen Graduate SchoolHarbin Institute of Technology

A novel closed-form expression for average capacity is derived for free-space optical（FSO） links over Gamma-Gamma turbulence channels by considering the effect of misalignment（pointing errors）.The simulation results show that the average capacity of the FSO links can be analyzed with the effects of atmospheric turbulence condition,beam width,detector size,jitter variable,and transmitted optical power. Meanwhile,the results are further provided to verify the accuracy of our mathematical *** work is useful for the FSO designer.

关键词： Atmospheric turbulence Errors Jitter Optical links

Characterization of ion-implanted 4H-SiC Schottky barrier diodes

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第1期19卷 456-460页

作者：王守国张岩张义门张玉明 Department of Electronic and information Engineering Harbin Institute of Technology Shenzhen Graduate School school of information Science and Technology Northwest University school of Microelectronics Xidian University

Ion-implantation layers are fabricated by multiple nitrogen ion-implantations （3 times for sample A and 4 times for sample B） into a p-type 4H-SiC epitaxial layer. The implantation depth profiles are calculated by using the Monte Carlo simulator TRIM. The fabrication process and the I-V and C V characteristics of the lateral Ti/4H-SiC Schottky barrier diodes （SBDs） fabricated on these multiple box-like ion-implantation layers are presented in detail. Measurements of the reverse I V characteristics demonstrate a low reverse current, which is good enough for many SiC-based devices such as SiC metal-semiconductor field-effect transistors （MESFETs）, and SiC static induction transistors （SITs）. The parameters of the diodes are extracted from the forward I-V and C-V characteristics. The values of ideality factor n of SBDs for samples A and B are 3.0 and 3.5 respectively, and the values of series resistance Rs are 11.9 and 1.0 kf~ respectively. The values of barrier height φB of Ti/4H-SiC are 0.95 and 0.72 eV obtained by the I-V method and 1.14 and 0.93 eV obtained by the C-V method for samples A and B respectively. The activation rates for the implanted nitrogen ions of samples A and B are 2% and 4% respectively extracted from C V testing results.

关键词： silicon carbide ion-implantation Schottky barrier diodes barrier height