检索结果-南通市图书馆

Spatial and Temporal Variability of N, P and K Balances for Agroecosystems in China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2005年第3期15卷 347-355页

作者： SHENRun-Ping SUNBo ZHAOQi-Guo InstituteofSoilscience ChineseAcademyofSciencesNanjing210008（China）／／DepartmentofSpatialInformationScienceNanjingUniversityofInformationScienceandTechnologyNanjing210044（China） InstituteofSoilscience ChineseAcademyofSciencesNanjing210008（China）

Nitrogen, phosphorus, and potassium balances for agroecosystems in China from 1993 to 2.01 were calculated at national and provincial levels using statistical data and related parameters, and their spatial and temporal variabilities were analyzed with GIS to estimate the potential impacts of nutrient N, P and K surpluses or deficits to soil, water and air. At the national scale, the N and P balances from 1993 to 2.01 showed a surplus, with the nitrogen surplus remaining relatively stable from 1997—2.01. Although during this period the P surplus pattern was similar to N, it had smaller values and kept increasing as the use of phosphate fertilizer increased year by year. However, K was deficient from 1993 to 2.01 even though from 1999 to 2.01 the K deficit decreased. The spatial analysis revealed higher N surpluses in the more developed southeastern provinces and lowest in the western and northern provinces where there was less chemical fertilizer input. The serious K deficit mainly occurred in Shanghai and Beijing municipalities, Jiangsu, Zhejiang and Hubei provinces, and Xinjiang autonomous regions. For the years 1992. 1996 and 2.01, N surpluses and K deficits had significant positive spatial correlations with per capita gross domestic product (GDP), per capita gross industrial output value, and per capita net income of rural households. This showed that the level of economic development played an important role on nutrient balances in the agroecosystems.

关键词： China economic factors NPK balance spatial and temporal variability

Eavesdropping in a quantum secret sharing protocol based on Grover algorithm and its solution

在线全文

学校读者我要写书评

暂无评论

science China(Physics,Mechanics & Astronomy) 2010年第3期53卷 491-495页

作者： HAO Liang1, LI JunLin1 & LONG GuiLu1,2.1Key laboratory for Atomic and Molecular Nanosciences and Department of Physics, Tsinghua University, Beijing 100084, China 2.singhua {2. laboratory for information science and technology, Beijing 100084, China Key laboratory for Atomic and Molecular Nanosciences and Department of Physics Tsinghua University Beijing China Tsinghua national laboratory for {2. science and technology Beijing China

A detailed analysis has showed that the quantum secret sharing protocol based on the Grover algorithm (Phys Rev A, 2.03, 68: 02.306) is insecure. A dishonest receiver may obtain the full information without being detected. A quantum secret-sharing protocol is presents here, which mends the security loophole of the original secret-sharing protocol, and doubles the information capacity.

关键词： quantum secret sharing Grover algorithm quantum cryptography quantum search algorithm

Robust AVS audio watermarking

在线全文

学校读者我要写书评

暂无评论

science China(information sciences) 2010年第3期53卷 607-618页

作者： WANG Yong & HUANG JiWu Guangdong Key laboratory of information Security {2., School of information science and {2., Sun Yat-Sen University, Guangzhou 5102.5, China Guangdong Key laboratory of information Security {2. School of Information Science and Technology Sun Yat-Sen University Guangzhou China

Part Ⅲ of AVS (China Audio and Video Coding Standard) is the first generic audio standard proposed in China and is becoming popular in some applications. For MP3 audio, some effiorts have been made to solve the copyright pirating and malicious modifications by the way of watermarking. To our best knowledge, similar work on the AVS audio has not been explored. In this paper, we present a novel robust watermarking algorithm for AVS audio. We find that the frame type in the AVS coded process can be used as a robust feature for watermarking. Then we design a novel watermarking algorithm which is integrated into the AVS audio coding process. The watermark bits are embedded into the compressed bit stream. At the extracting end, the watermark bits can be extracted from the compressed bit stream directly. This algorithm achieves robustness to decoding/re-coding attacks, and has low computation complexity for both embedding and extracting while preserving the quality of the audio signals.

关键词： AVS audio security problems robust watermarking

Toward high-performance two-dimensional black phosphorus electronic and optoelectronic devices

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第3期26卷 137-147页

作者：李学飞熊雄吴燕庆 Wuhan national High Magnetic Field Center and School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China Wuhan national High Magnetic Field Center and School of Optical and Electronic information Huazhong University of Science and Technology Wuhan 430074 China

Recently, black phosphorus （BP） has joined the two-dimensional material family as a promising candidate for elec- tronic and photonic applications due to its moderate bandgap, high carrier mobility, and unusual in-plane anisotropy. Here, we review recent progress in BP-based devices, such as field-effect transistors, contact resistance, quantum transport, stabil- ity, photodetector, heterostructure, and in-plane anisotropy. We also give our perspectives on future BP research directions.

关键词： black phosphorus transistors mobility photodetector

Perceptual video hashing robust against geometric distortions

在线全文

学校读者我要写书评

暂无评论

science China(information sciences) 2012年第7期55卷 1520-1527页

作者： XIANG ShiJun 1,4 ,YANG JianQuan 2.& HUANG JiWu 3 1 School of information science and {2.,Jinan University,Guangzhou 510632.China 2.Shenzhen Institutes of Advanced {2.,Chinese Academy of sciences,Shenzhen 518055,China 3 School of information science and {2.,Sun Yat-sen University,Guangzhou 5102.5,China 4 State Key laboratory of information Security,Institute of Software,Chinese Academy of sciences,Beijing 100049,China School of information science and {2. Jinan University Guangzhou China State Key laboratory of information Security Institute of Software Chinese Academy of Sciences Beijing China Shenzhen Institutes of Advanced technology Chinese Academy of Sciences Shenzhen China School of information science and {2. Sun Yat-sen University Guangzhou China

In this paper,we propose a robust perceptual hashing algorithm by using video luminance histogram in *** underlying robustness principles are based on three main aspects:1) Since the histogram is independent of position of a pixel,the algorithm is resistant to geometric deformations; 2. the hash is extracted from the spatial Gaussian-filtering low-frequency component for those common video processing operations such as noise corruption,low-pass filtering,lossy compression,etc.; 3) a temporal Gaussian-filtering operation is designed so that the hash is resistant to temporal desynchronization operations,such as frame rate change and *** a result,the hash function is robust to common geometric distortions and video processing *** results show that the proposed hashing strategy can provide satisfactory robustness and uniqueness.

关键词： video hashing geometric distortion histogram Gaussian filtering

A TTCN-3-based protocol testing system and its extension

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 in China(Series F) 2008年第11期51卷 1703-1722页

作者： YIN Xia1,3,WANG ZhiLiang2.3,JING ChuanMing1,3 & SHI XinGang2.3 1 Department of Computer science and technology,Tsinghua University,Beijing 100084,China 2.Network Research Center,Tsinghua University,Beijing 100084,China 3 Tsinghua {2. laboratory for information science and technology(TNList) ,Beijing 100084,China Department of Computer science and technology Tsinghua University Beijing China Tsinghua national laboratory for {2. science and technology (TNList) Beijing China Network Research Center Tsinghua University Beijing China

The protocol testing technology used in the next generation Internet should satisfy some new challenges and requirements. This paper focuses on the test suite description and test implementation techniques. TTCN-3 is chosen as the test suite description language and extended in both syntax and semantics to satisfy the requirements of protocol robustness testing. PITSv3, a protocol integrated testing system based on TTCN-3, is developed, and the extensions for robustness testing are implemented. Finally, two practical test applications are presented.

关键词： protocol testing TTCN-3 PITSv3 robustness testing

Coupling Losses and Discrimination of Annular Waveguide Laser Resonators

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Lasers 1999年第2期8卷 14-20页

作者： WANG Youqing HUANG Xintang CHEN Q. M. QIU J. L. XU Q. Y. (national lab. of Laser {2., Huazhong University of science and {2., Wuhan 430074, China) 华中理工大学激光技术国家重点实验室湖北武汉 430074 华中理工大学激光技术国家重点实验室湖北武汉

１ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅｔｈｅｆｉｒｓｔｒｅａｌｉｚａｔｉｏｎｏｆｔｈｅｏｐｅｒａｔｉｏｎｏｆａｗａｖｅｇｕｉｄｅｇａｓｌａｓｅｒｂｙＳｍｉｔｈ［１］ｉｎ１９７１，ｃｏｎｓｉｄｅｒａｂｌｅｓｔｕｄｉｅｓｈ... 详细信息

１ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅｔｈｅｆｉｒｓｔｒｅａｌｉｚａｔｉｏｎｏｆｔｈｅｏｐｅｒａｔｉｏｎｏｆａｗａｖｅｇｕｉｄｅｇａｓｌａｓｅｒｂｙＳｍｉｔｈ［１］ｉｎ１９７１，ｃｏｎｓｉｄｅｒａｂｌｅｓｔｕｄｉｅｓｈａｖｅｂｅｅｎｍａｄｅｏｎｔｈｅｗ...

关键词： coupling loss annular waveguide laser toric mirror

Tissue P systems with cell separation: attacking the partition problem

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) 2011年第2期54卷 293-304页

作者： ZHANG XingYi1, WANG Shuo2. NIU YunYun2.& PAN LinQiang2.1Key lab of Intelligent Computing and Signal Processing of Ministry of Education, School of Computer science and {2., Anhui University, Hefei 2.0039, China 2.mage Processing and Intelligent Control Key laboratory of Education Ministry of China, Department of Control science and Engineering, Huazhong University of science and {2., Wuhan 430074, China Key lab of Intelligent Computing and Signal Processing of Ministry of Education School of Computer Science and Technology Anhui University Hefei China Image Processing and Intelligent Control Key laboratory of Education Ministry of China Department of Control Science and Engineering Huazhong University of Science and Technology Wuhan China

Tissue P systems are distributed parallel and non-deterministic computing models in the framework of membrane computing, which are inspired by intercellular communication and cooperation between neurons. Recently, cell separation is introduced into tissue P systems, which enables systems to generate an exponential workspace in a polynomial time. In this work, the computational power of tissue P systems with cell separation is investigated. Specifically, a uniform family of tissue P systems with cell separation is constructed for effciently solving a well-known NP-complete problem, the partition problem.

关键词： membrane computing tissue P system cell separation partition problem

Salient region detection and segmentation for general object recognition and image understanding

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) 2011年第12期54卷 2481-2490页

作者： HUANG TieJun 1 , TIAN YongHong 1 , LI Jia 2.& YU HaoNan 11 national Engineering laboratory for Video {2., School of Electrical Engineering and Computer science, Peking University, Beijing 100871, China 2.Key laboratory of Intelligent information Processing, Institute of Computing {2., Chinese Academy of sciences, Beijing 100190, China national Engineering laboratory for Video {2. School of Electrical Engineering and Computer Science Peking University Beijing China Key laboratory of Intelligent information Processing Institute of Computing Technology Chinese Academy of Sciences Beijing China

General object recognition and image understanding is recognized as a dramatic goal for computer vision and multimedia retrieval. In spite of the great efforts devoted in the last two decades, it still remains an open problem. In this paper, we propose a selective attention-driven model for general image understanding, named GORIUM (general object recognition and image understanding model). The key idea of our model is to discover recurring visual objects by selective attention modeling and pairwise local invariant features matching on a large image set in an unsupervised manner. Towards this end, it can be formulated as a four-layer bottom-up model, i.e., salient region detection, object segmentation, automatic object discovering and visual dictionary construction. By exploiting multi-task learning methods to model visual saliency simultaneously with the bottom-up and top-down factors, the lowest layer can effectively detect salient objects in an image. The second layer exploits a simple yet effective learning approach to generate two complementary maps from several raw saliency maps, which then can be utilized to segment the salient objects precisely from a complex scene. For the third layer, we have also implemented an unsupervised approach to automatically discover general objects from large image set by pairwise matching with local invariant features. Afterwards, visual dictionary construction can be implemented by using many state-of-the-art algorithms and tools available nowadays.

关键词： object recognition image understanding visual saliency salient object segmentation visual dictionary