期刊文献+
共找到26篇文章
< 1 2 >
每页显示 20 50 100
叠加在半色调图象上的两级图象的快速分离算法
1
作者 杨敬安 《应用科学学报》 CAS CSCD 1994年第1期78-81,共4页
叠加在半色调图象上的两级图象的快速分离算法杨敬安(合肥工业大学)关键词:分块密度差算法,半色调图象,快速分离算法,两级图象.0引言在图象文件处理及分析过程中,对由两级和半色调图象构成的文件,通常利用分块密度差(Blo... 叠加在半色调图象上的两级图象的快速分离算法杨敬安(合肥工业大学)关键词:分块密度差算法,半色调图象,快速分离算法,两级图象.0引言在图象文件处理及分析过程中,对由两级和半色调图象构成的文件,通常利用分块密度差(BlockDivisionDensity... 展开更多
关键词 色调图 分离算法 两级图
下载PDF
误差分散类逆半调图象的质量评价方法 被引量:4
2
作者 赵媛 曾平 《计算机工程与应用》 CSCD 北大核心 2004年第34期75-77,共3页
提出一套针对误差分散类逆半调图象的质量评价方法。在分析了误差分散半调图象退化特性的基础上,将逆半调图象中的噪声表征为图象频率失真和附加噪声的联合作用,据此确定了该评价方法中的像素级差异测度,频谱距测度,边缘质量测度和附加... 提出一套针对误差分散类逆半调图象的质量评价方法。在分析了误差分散半调图象退化特性的基础上,将逆半调图象中的噪声表征为图象频率失真和附加噪声的联合作用,据此确定了该评价方法中的像素级差异测度,频谱距测度,边缘质量测度和附加噪声测度;通过对不同误差分散类逆半调图象序列的实验分析了这些测度的性能.实验证明在评价逆半调图象时,该套评价方法较目前广泛使用的峰值信噪比(PSNR)测度更为全面。 展开更多
关键词 误差分散逆调图 质量测度 方差分析方法
下载PDF
半色调图象压缩编码器的设计与实现
3
作者 黄德胜 《计算机工程与应用》 CSCD 北大核心 1998年第3期63-64,共2页
本文针对印刷等行业处理的半色调图象特点,设计并实现一种压缩与解压缩编解码器。这种半色调图象压缩设备具有压缩倍率高,适应调幅加网和调频加网方式、成本低廉等优点,是印刷等行业在运用数字化技术存储和传输图片时提高经济效益的... 本文针对印刷等行业处理的半色调图象特点,设计并实现一种压缩与解压缩编解码器。这种半色调图象压缩设备具有压缩倍率高,适应调幅加网和调频加网方式、成本低廉等优点,是印刷等行业在运用数字化技术存储和传输图片时提高经济效益的重要设备。 展开更多
关键词 色调图 处理 压缩 编码器 编码器
下载PDF
PostScript 语言的半色调技术
4
作者 黄仁立 《北京印刷学院学报》 1993年第1期86-93,共8页
PostScript语言具有调整灰色层次的功能,其实质是PostScript语言允许用户采用“网屏”技术,该语言中的网屏与传统照相用网屏(screens)很相似。由于采用网屏,便可实现图像加网(screening)从而使图象具有层次或灰度的印象。加网技术应用... PostScript语言具有调整灰色层次的功能,其实质是PostScript语言允许用户采用“网屏”技术,该语言中的网屏与传统照相用网屏(screens)很相似。由于采用网屏,便可实现图像加网(screening)从而使图象具有层次或灰度的印象。加网技术应用于照片和其它连续调(continuoustone)图象(图象除有黑白颜色外还包含灰色)称为成半色调(halftoning).PostScript语言提供许多调整图象灰阶的技术措施:调整灰色网屏分辨率(resolution),调整网屏方位(orientation),调整组成各种网屏的网纹形状。 展开更多
关键词 网屏频率 POSTSCRIPT语言 色调图 色调技术 网格矩阵 灰度级 算符 激光印字机 输出设备 解释器
下载PDF
Dictyotenguna choui,a new genus and species of Dictyopharinae(Hemiptera:Fulgoromorpha:Dictyophar-idae) from China
5
作者 宋志顺 梁爱萍 《Entomotaxonomia》 CSCD 北大核心 2012年第2期207-214,共8页
A new Oriental dictyopharid genus and species, Dictyotenguna choui gen. n., sp. n., is described and illustrated from China. A brief review of the family Dictyopharidae from the Oriental and eastern Palaearctic Region... A new Oriental dictyopharid genus and species, Dictyotenguna choui gen. n., sp. n., is described and illustrated from China. A brief review of the family Dictyopharidae from the Oriental and eastern Palaearctic Regions is provided. 展开更多
关键词 HEMIPTERA DICTYOPHARIDAE new genus new species China
下载PDF
MOTION AND INTENSITY AND IMPACT CHARACTERISTICS OF TROPICAL CYCLONE AFFECTING THE LIAODONG PENINSULA 被引量:1
6
作者 梁军 陈联寿 王式功 《Journal of Tropical Meteorology》 SCIE 2005年第2期131-143,共13页
Conventional data and the Yearbook on Tropical Cyclones (TC) data from 1971 to 2000 are used to study the climate and disaster features of TC affecting the Liaodong Peninsula. Results indicate that interannual change ... Conventional data and the Yearbook on Tropical Cyclones (TC) data from 1971 to 2000 are used to study the climate and disaster features of TC affecting the Liaodong Peninsula. Results indicate that interannual change of TC activities is obvious. Different sources of TC have different impacts on the area of interest. Intensity and moving speed of TC vary substantially in the progress of northward movement. Besides, tracks and damage distributions of TC are quite different. 展开更多
关键词 tropical cyclones impacts on the Liaodong Peninsula climate features STATISTICS
下载PDF
Radius of Starlikeness for Class S(a,n)and Its Extension
7
作者 蒋润荣 《Chinese Quarterly Journal of Mathematics》 CSCD 1993年第4期40-46,共7页
This paper obtain that the radius of starlikeness for class S(α,n)in [1] is,tespectivety, where α_ is unique solution of equation (αα)^(1/2)=σwith a in (0.1),and α-[1+(1-2α)r^(2n)]/(1-r^(2n)),σ =[1-(1-2α)r~]... This paper obtain that the radius of starlikeness for class S(α,n)in [1] is,tespectivety, where α_ is unique solution of equation (αα)^(1/2)=σwith a in (0.1),and α-[1+(1-2α)r^(2n)]/(1-r^(2n)),σ =[1-(1-2α)r~]/(1+r~).Futhermore,we consider an extension of class S(α,n):Let S(α、β、n) denote the class of functions f(z)=z+α_z^(n+1)+…(n≥1)that are analytie in |z|<1 such that f(z)/g (z)∈p(α,n)[1],where g(z)∈S~*(β)[2].This paper prove that the radius of starlikeness of class S(α, β,n) is given by the smallest positive root(less than 1)of the following equations (1-2α)(1-2β)r^(2)-2[1-α-β-n(1-α)]r^+1=0.0≤α≤α_0, (1-α)[1-(1-2β)r~]-n[r^(1+r^)=0.,α_0≤α<1. where α=[1+(1-2α)r^(2)]/(1-r^(2)(0≤r<1),α_0(?(0,1) is some fixed number.This result is also the cxtension of well-known results[T.Th3] and [8,Th3] 展开更多
关键词 pick theorem starlike function radius of starlikencss
下载PDF
Crystal Structure and Conformation of 2'-C-Ethoxy-3',5'-O-(tetraisopropyldisiloxane-1,3-diyl)uridine
8
作者 迟国臣 陈如玉 +1 位作者 王宏根 姚心侃 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2001年第3期187-190,共4页
The title compound, C23H42N2O8Si2, Mr=530.77, crystallizes in the monoclinic system, space group P21, with a=10.577(5), b=10.528(2), c=13.374(5)?, (=100.63(3)(, V=1461(2)?3, Z=2, Dx=1.207g/cm3, ((MoK()=0.71073?, (=1.5... The title compound, C23H42N2O8Si2, Mr=530.77, crystallizes in the monoclinic system, space group P21, with a=10.577(5), b=10.528(2), c=13.374(5)?, (=100.63(3)(, V=1461(2)?3, Z=2, Dx=1.207g/cm3, ((MoK()=0.71073?, (=1.590mm-1, T=299(1K, F(000)=572, R=0.070 and Rw=0.075 for 1232 observed reflections with I (3((I). The analysis result indicates that the configuration of the title compound at C(2() is S. In the crystal state the molecule has anti- conformation about glycosidic bond with the torsion angle -126.96(. The sugar ring is puckered with C3(-endo-C4(-exo, and the conformation of the C(4()-C(5() bond is +sc. 展开更多
关键词 NUCLEOSIDES ketonucleosides semi-ketal CONFORMATION
下载PDF
THE ANALYSIS OF TROPICAL CYCLONE PRECIPITATION AFFECTING THE LIAODONG PENINSULA
9
作者 梁军 陈联寿 王式功 《Journal of Tropical Meteorology》 SCIE 2006年第1期99-100,共2页
1 INTRODUCTION Tropical cyclones (TCs) moving north and getting to the Liaodong Peninsula and waters of the Yellow and Bohai Seas are in their late phase of life cycle. While weakening rapidly, TCs carry a large amo... 1 INTRODUCTION Tropical cyclones (TCs) moving north and getting to the Liaodong Peninsula and waters of the Yellow and Bohai Seas are in their late phase of life cycle. While weakening rapidly, TCs carry a large amount of warm and humid air that forms heavy rainfall by itself on the one hand and interact with westerlies in the middle latitudes on the other. With their warm-core structure destroyed by intruded cooler air, TCs absorb baroclinic energy while it weakens and experiences extratropical transition (ET). With right conditions and complicated topographic features of the peninsula, the transformed extratropical cyclone evolves to intensify heavy rainfall in most cases and even results in secondary disasters like storm surges. Therefore, the extratropical transition of TCs is usually responsible for more serious damage in mid-latitude areas. For the forecast of heavy rain associated with north-going TCs experiencing extratropical transition, it not only involves their own intensity and structure but also the distribution of the surrounding field and its interactions with TCs. Most of the present studies discuss TCs-inflicted heavy rains or those taking place south of the Shandong Peninsula. Focusing on intense precipitation resulted from TCs over the Liaodong Peninsula, this work analyzes the distribution of the ambient field and physical quantities hoping to help forecast TCs-related heavy rains accurately. 展开更多
关键词 Tropical cyclone Liaodong peninsula comparative analysis severe precipitation
下载PDF
Modeling Gross Primary Production by Integrating Satellite Data and Coordinated Flux Measurements in Arid and Semi-Arid China 被引量:1
10
作者 WANG He-Song JIA Gen-Suo +2 位作者 FENG Jin-Ming ZHAO Tian-Bao MA Zhu-Guo 《Atmospheric and Oceanic Science Letters》 2010年第1期7-13,共7页
Assessing large-scale patterns of gross primary production (GPP) in arid and semi-arid (ASA) areas is important for both scientific and practical purposes.Remote sensing-based models,which integrate satellite data wit... Assessing large-scale patterns of gross primary production (GPP) in arid and semi-arid (ASA) areas is important for both scientific and practical purposes.Remote sensing-based models,which integrate satellite data with input from ground-based meteorological measurements and vegetation characteristics,improve spatially extended estimates of vegetation productivity with high accuracy.In this study,the authors simulated GPP in ASA areas by integrating moderate resolution imaging spectral radiometer (MODIS) data with eddy covariance and meteorological measurements at the flux tower sites using the Vegetation Photosynthesis Model (VPM),which is a remote sensing-based model for analyzing the spatial pattern of GPP in different land cover types.The field data were collected by coordinating observations at nine stations in 2008.The results indicate that in the region during the growing season GPP was highest in cropland sites,second highest in woodland sites,and lowest in grassland sites.VPM captured the temporal and spatial characteristics of GPP for different land covers in ASA areas.Further,Enhanced Vegetation Index (EVI) had a strong liner relationship with GPP in densely vegetated areas,while the Normalized Difference Vegetation Index (NDVI) had a strong liner relationship with GPP over less dense vegetation.This study demonstrates the potential of satellite-driven models for scaling-up GPP,which is a key component for studying the carbon cycle at regional and global scales. 展开更多
关键词 gross primary production vegetation photo- synthesis model eddy covariance remote sensing coordinated observation arid and semiarid areas
下载PDF
A Equivalent Definition of Radical Property
11
作者 田震 《Chinese Quarterly Journal of Mathematics》 CSCD 1993年第3期50-51,共2页
This paper study the radical propertys in the sence of Amitsut and Kurosh from reference[1].
关键词 radical property of ring R-rmg R-ideal R-radical R-simesimple zorn lemma
下载PDF
DESIGN AND IMPLEMENTATION OF CMOS IMAGE SENSOR
12
作者 Liu Yu Wang Guoyu 《Journal of Electronics(China)》 2007年第1期95-99,共5页
A single Complementary Metal Oxide Semiconductor (CMOS) image sensor based on 0.35μm process along with its design and implementation is introduced in this paper. The pixel ar-chitecture of Active Pixel Sensor (APS) ... A single Complementary Metal Oxide Semiconductor (CMOS) image sensor based on 0.35μm process along with its design and implementation is introduced in this paper. The pixel ar-chitecture of Active Pixel Sensor (APS) is used in the chip,which comprises a 256×256 pixel array together with column amplifiers,scan array circuits,series interface,control logic and Analog-Digital Converter (ADC). With the use of smart layout design,fill factor of pixel cell is 43%. Moreover,a new method of Dynamic Digital Double Sample (DDDS) which removes Fixed Pattern Noise (FPN) is used. The CMOS image sensor chip is implemented based on the 0.35μm process of chartered by Multi-Project Wafer (MPW). This chip performs well as expected. 展开更多
关键词 Complementary Metal Oxide Semiconductor (CMOS) Active Pixel Sensor (APS) Fill factor Dynamic Digital Double Sample (DDDS) Fixed Pattern Noise (FPN)
下载PDF
Charmonium Spectrum and Their Transitions in Relativistic Quark Models 被引量:1
13
作者 Bhaghyesh K.B. Vijaya Kumar 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第6期1044-1048,共5页
Using the phenomenological relativistic harmonic model (RHM) for quarks, we have obtained the masses of S wave charmonium states. The full Hamiltonian used in the investigation has Lorentz scalar plus vector confine... Using the phenomenological relativistic harmonic model (RHM) for quarks, we have obtained the masses of S wave charmonium states. The full Hamiltonian used in the investigation has Lorentz scalar plus vector confinement potential, along with the confined one gluon exchange potential (COGEP). A good agreement with the experimental masses for the ground state and the radially excited states is obtained for both the triplet and singlet S wave mesons. The calculated charge radii, meson decay constants, leptonic decay width, two photon decay width, and the radiative M1 decay width are in good agreement with the experimental results. 展开更多
关键词 quark model confined-one-gluon-exchange potential S-wave charmonium states charge radii decay constants Leptonic two photon and radiative decays
下载PDF
清华简《筮法·爻象》刍论 被引量:4
14
作者 蔡飞舟 《周易研究》 CSSCI 2017年第3期33-41,共9页
清华大学藏战国竹简《筮法》所载四恶爻爻象,当来源于四方卦象。而卦祟之形成,则是卦象与恶爻爻象结合所致。至若《周易》中半象之例,亦是产生于三画卦象流行之后。学者或据《筮法》及《周易》而论定卦象经由爻象、半象而来,则论据尚显... 清华大学藏战国竹简《筮法》所载四恶爻爻象,当来源于四方卦象。而卦祟之形成,则是卦象与恶爻爻象结合所致。至若《周易》中半象之例,亦是产生于三画卦象流行之后。学者或据《筮法》及《周易》而论定卦象经由爻象、半象而来,则论据尚显不足。 展开更多
关键词 《筮法》 半象
原文传递
On Integrated Solutions to Abstract Cauchy Problem
15
作者 张升海 《Chinese Quarterly Journal of Mathematics》 CSCD 1997年第2期24-28, ,共5页
Integrated semigroups which are not exponentially bounded have been studied. The integrated solutions of inhomogeneous and nonlinear abstract Caucby problems are discussed. The reults extends and improves the theorems... Integrated semigroups which are not exponentially bounded have been studied. The integrated solutions of inhomogeneous and nonlinear abstract Caucby problems are discussed. The reults extends and improves the theorems in [1]. 展开更多
关键词 integrated semigroups abstract Cauchy problems integrated solutions
下载PDF
Semi-Automatic Complex Emotion Categorization and Ontology Construction from Chinese Knowledge 被引量:2
16
作者 Jiang Peilin Wang Fei Ren Fuji 《China Communications》 SCIE CSCD 2012年第3期28-37,共10页
In order to recognize one's intention from the communication, both the meaning and the emotion are necessary to be interpreted correctly. But until now the study of fine-grained theory of emotion is still full of cha... In order to recognize one's intention from the communication, both the meaning and the emotion are necessary to be interpreted correctly. But until now the study of fine-grained theory of emotion is still full of challenges. This paper analy- zes emotion category according to the statistics of Affective Word (AW) hierarchy and descries an e- motion ontology from Chinese knowledge resource semi-automatically created for human machine in- teraction. The emotion hierarchy is called complex emotion. Firstly, over 7 000 AWs have been annota- ted and theft detailed explanations had been collected for an affective lexicon and then the consistent rela- tionships are automatically parsed and a serial of e- motion hierarchical structures are built up. More than 50 affective categories are extracted by a lexical clustering algorithm and about 5 000 nouns and ad- jectives and 2 000 verbs are categorized into the predicate hierarchy. The results have been evaluated to be valid by two metrics. 展开更多
关键词 natural language processing affectivecomputing emotion ontology affective clustering AW annotation
下载PDF
A Case Study of a Typical Dust Storm Event over the Loess Plateau of Northwest China
17
作者 LING Xiao-Lu GUO Wei-Dong +1 位作者 ZHAO Qian-Fei ZHANG Bei-Dou 《Atmospheric and Oceanic Science Letters》 2011年第6期344-348,共5页
Enhanced observational meteorological elements,energy fluxes,and the concentration of dust aerosols collected from the Semi-Arid Climate Observatory and Laboratory(SACOL) during a typical dust storm period in March 20... Enhanced observational meteorological elements,energy fluxes,and the concentration of dust aerosols collected from the Semi-Arid Climate Observatory and Laboratory(SACOL) during a typical dust storm period in March 2010 at Lanzhou were used in this paper to investigate the impact of dust aerosols on near surface atmospheric variables and energy budgets.The results show that the entire dust storm event was associated with high wind velocities and decreasing air pressure,and the air changed from cold and wet to warm and dry and then recovered to its initial state.The response of energy fluxes occurred behind meteorological elements.At high dust concentration periods,the net radiation was significantly less in the daytime and higher at night,while the heat fluxes displayed the same trend,indicating the weakening of the land-atmosphere energy exchange.The results can be used to provide verification for numerical model results in semi-arid areas. 展开更多
关键词 case study dust storm energy budget Loess Plateau
下载PDF
Zonal Mean Mode of Global Warming over the Past 50 Years
18
作者 DAI Xin-Gang WANG Ping 《Atmospheric and Oceanic Science Letters》 2010年第1期45-50,共6页
Zonal mean annual temperature trends were estimated using four reanalysis and three analysis grid datasets. The trends over land and for the entire globe were estimated from 1958-2001 and 1979-2007, respectively. Esti... Zonal mean annual temperature trends were estimated using four reanalysis and three analysis grid datasets. The trends over land and for the entire globe were estimated from 1958-2001 and 1979-2007, respectively. Estimates of temperature trends over land from Climate Research Unit (CRU) analysis data indicate more intense wanning moving northward, at a rate of about 3.5℃ per century at 65°N, then declining further to the north. CRU estimates indicated dramatic warming over the latitudes of the Antarctic Peninsula, with a localized cooling trend at 45°S. A global estimate was conducted by comparing estimates of the reanalysis datasets. Temperature distribution trends of the reanalysis data were similar to those generated by land observations but with large bias in the Polar Regions. The bias could be reduced by comparing these estimates with those from the analysis data at high latitudes. Extreme warming trends were esti- mated at rates of 2.9℃-3.5℃ per century in the Arctic and 3.2℃-4.7℃ per century in the Antarctic for 1958-2001. Surface warming was even more intense in the Northern Hemisphere for 1979-2007, with extreme arctic warming rates ranging from 8.5℃-8.9℃ per century, as estimated by the analysis and reanalysis datasets. Trends over Antarctica for this period were contradictory, as Japan Meteorological Agency (JMA) reanalysis (JRA-25) indicated a cooling trend at about -7℃ per century, while other reanalysis datasets showed sharp warming over the continent. 展开更多
关键词 global warming zonal mean mode REANALYSIS analysis data BIAS
下载PDF
Evolution of Damage on Historical Heritage Buildings in Presence of Catastrophic Events and Aggressive Natural Phenomena
19
作者 Elsa Garavaglia Chiara Molina 《Journal of Civil Engineering and Architecture》 2011年第7期585-595,共11页
The feasibility analysis of projects for the preservation of the historical heritage buildings is an important problem concerning the evaluation of "the total cost of intervention", which includes all the future dam... The feasibility analysis of projects for the preservation of the historical heritage buildings is an important problem concerning the evaluation of "the total cost of intervention", which includes all the future damage costs. The total cost of intervention represents a suitable measure of the expected deterioration risk and its evolution obviously depends on the damage process which buildings are subjected to. That damage phenomena affecting masonry buildings pleased into an aggressive environment are suitably modelled by renewal processes: this happens both in the case of catastrophic events, or in the case of the so-called "natural aging", in which damage comes off gradually in time. In the hypothesis ofa Markovian renewal process (Mrp) describing the damage process, the total cost of all the future damage is evaluated taking into account both the damage aspects: damages due to catastrophic aspects and damages due to aggressive environment, supposing different maintenance and/or rehabilitation scenarios. A semi-Markov process (s-Mp) is defined to model the damage rehabilitation history of buildings in presence of seismic events, natural ageing and rehabilitation strategies. The expected rewards connected to the process are defined; they represent a significant measure of the risk. 展开更多
关键词 Historical heritage buildings damaging phenomena rehabilitation strategies semi-Markov and renewal processes expected rewards.
下载PDF
Ishikawa Iterative Process with Errors for Lipschitzian and φ-Hemicontractive Mappings in Banach Spaces 被引量:1
20
作者 周海云 《Journal of Mathematical Research and Exposition》 CSCD 2000年第2期159-165,共7页
本文在任意Banach空间中研究了Lipschitzφ-半压缩映象与φ-强拟增生映象的带误差项的Ishikawa迭代过程,使用新的分析技巧建立了几个强收敛定理.
关键词 Ishikawa iteration with errors -strongly quasi-accretive mapping hemicontraction arbitrary Banach space.
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部