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均值量化与中值量化光栅性能的理论研究
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作者 陈炎明 何玉明 胡而已 《光子学报》 EI CAS CSCD 北大核心 2008年第4期804-808,共5页
对相移技术的投影栅相位法的传统中值量化方法提出改进,设计和制作出小误差、低高阶谐波的均值量化光栅.理论讨论了相位值、离散等级和量化等级等因素对两种量化光栅性能的影响;在标准偏差和频谱分布两方面比较后,得出均值量化光栅性能... 对相移技术的投影栅相位法的传统中值量化方法提出改进,设计和制作出小误差、低高阶谐波的均值量化光栅.理论讨论了相位值、离散等级和量化等级等因素对两种量化光栅性能的影响;在标准偏差和频谱分布两方面比较后,得出均值量化光栅性能优于中值量化光栅且更接近正弦光栅的结论. 展开更多
关键词 均值量化 中值量化 投影光栅 三维形貌测量
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基于离散小波变换和位平面分解的灰度水印算法
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作者 王飞 陈青 周广州 《数据通信》 2016年第2期32-35,共4页
为了有效地保护数字图像的知识产权,以小波变换及中值量化相关知识为基础,提出一种灰度水印算法。该算法首先将灰度水印图像进行置乱变换;然后利用位平面分解和压缩算法对灰度水印图像进行预处理操作,将灰度水印图像转换成二值信号序列... 为了有效地保护数字图像的知识产权,以小波变换及中值量化相关知识为基础,提出一种灰度水印算法。该算法首先将灰度水印图像进行置乱变换;然后利用位平面分解和压缩算法对灰度水印图像进行预处理操作,将灰度水印图像转换成二值信号序列;最后将二值水印信号运用中间值量化算法嵌入中频子带中。实验结果表明,该算法不仅具有较好的不可见性,且对JPEG压缩、剪切、噪声等常见的图像攻击具有较强的鲁棒性。 展开更多
关键词 小波变换 中值量化 位平面分解 鲁棒性
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基于MCCQ的民间布老虎色彩特征提取及设计实践 被引量:17
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作者 陈登凯 王瑶 《包装工程》 CAS 北大核心 2019年第24期45-49,共5页
目的布老虎是中国传统民间玩具,是现存民间艺术的典型代表。旨在提取民间布老虎主要色彩语言及色彩组合规律,在此基础上进行相关文创产品的设计实践,以验证色彩提取方法的适用性和易用性。方法首先通过桌面调查、用户访谈、实际操作等... 目的布老虎是中国传统民间玩具,是现存民间艺术的典型代表。旨在提取民间布老虎主要色彩语言及色彩组合规律,在此基础上进行相关文创产品的设计实践,以验证色彩提取方法的适用性和易用性。方法首先通过桌面调查、用户访谈、实际操作等调研方法,了解现今民间布老虎制作的手法工艺及布老虎手艺人的生存现状;再结合现有的图像识别技术,选择中值切割颜色量化算法(MCCQ)进行民间布老虎的色彩特征分析,以罗列出布老虎前二十四个主要色彩搭配。结论总结归纳了传统布老虎形象的典型色彩语言和文化特征,提炼出了民间布老虎色彩搭配规律并形成了可视化的配色图谱,为后续基于民间布老虎的相关设计创作和开发,提供了一定的参考价值,同时对于民间手工艺品色彩提取与应用,提供了新的思路和方法借鉴。 展开更多
关键词 民间布老虎 民俗色彩提取 布老虎配色图谱 中值切割颜色量化算法
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EXPERIMENTS ON ASSIMILATION OF INITIAL VALUES IN NUMERICAL PREDICTION OF A WARM-SECTOR PRECIPITATION IN SOUTH CHINA
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作者 张诚忠 万齐林 +2 位作者 黄燕燕 陈子通 丁伟钰 《Journal of Tropical Meteorology》 SCIE 2009年第1期73-77,共5页
In order to understand the impact of initial conditions upon prediction accuracy of short-term forecast and nowcast of precipitation in South China, four experiments i.e. a control, an assimilation of conventional sou... In order to understand the impact of initial conditions upon prediction accuracy of short-term forecast and nowcast of precipitation in South China, four experiments i.e. a control, an assimilation of conventional sounding and surface data, testing with nudging rainwater data and the assimilation of radar-derived radial wind, are respectively conducted to simulate a case of warm-sector heavy rainfall that occurred over South China, by using the GRAPES_MESO model. The results show that (1) assimilating conventional surface and sounding observations helps improve the 24-h rainfall forecast in both the area and order of magnitude; (2) nudging rainwater contributes to a significant improvement of nowcast, and (3) the assimilation of radar-derived radial winds distinctly improves the 24-h rainfall forecast in both the area and order of magnitude. These results serve as significant technical reference for the study on short-term forecast and nowcast of precipitation over South China in the future. 展开更多
关键词 South China initial conditions warm-sector precipitation numerical simulation experiment
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EVOLUTION OF MOIST POTENTIAL VORTICITY DURING A WARM-ZONE HEAVY RAINFALL EVENT IN THE PEARL RIVER DELTA
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作者 叶爱芬 李江南 +3 位作者 徐永辉 伍志方 何如意 蔡榕硕 《Journal of Tropical Meteorology》 SCIE 2011年第3期310-316,共7页
First,based on routine meteorological data,the synoptic characteristics of a heavy warm-sector rainfall that occurred on June 13,2008 in the Pearl River Delta were analyzed.Second,a mesoscale numerical model,Weather R... First,based on routine meteorological data,the synoptic characteristics of a heavy warm-sector rainfall that occurred on June 13,2008 in the Pearl River Delta were analyzed.Second,a mesoscale numerical model,Weather Research and Forecasting(WRFV2.2),was used to simulate the heavy rainfall. Diagnostic analyses were done of moist potential vorticity(MPV)for its horizontal components(MPV2) and vertical components(MPV1)based on the simulation results of WRFV2.2 to identify the mechanism of the rainfall development.The results showed that the heavy rainfall occurred when there were high MPV1 in the upper levels and low MPV1 and high MPV2 in the lower levels.Disturbances of high MPV1 in the upper levels came from the southwest or northwest,those of low MPV1 in the lower levels came from the southwest,and those of high MPV2 came from the south.Disturbances of low MPV1 at low levels were the direct cause of convective instability.Enhanced vertical shear of meridional wind led to increased MPV2 at lower levels,strengthened baroclinicity,and active warm and wet flows.These distributions of MPV helped to trigger the release of unstable energy and produce warm-sector heavy rainfall.As it integrates the evolution of dynamic and thermal fields,MPV is able to reveal the development of this heavy rainfall effectively. 展开更多
关键词 heavy rainfall MPV(moist potential vorticity) numerical simulation
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