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轮胎花纹沟的发声模拟计算 被引量:10
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作者 李福军 吴桂忠 《轮胎工业》 CAS 2006年第4期203-207,共5页
通过对不同花纹沟轮胎发声机理的研究,建立预测数学模型,模拟计算具体的发声情况,提高轮胎花纹的设计水平。研究结果表明。对于与轮胎中心线成一定角度的花纹沟。其深度和宽度对轮胎噪声的影响不大,而花纹沟角度的影响很大,其每增... 通过对不同花纹沟轮胎发声机理的研究,建立预测数学模型,模拟计算具体的发声情况,提高轮胎花纹的设计水平。研究结果表明。对于与轮胎中心线成一定角度的花纹沟。其深度和宽度对轮胎噪声的影响不大,而花纹沟角度的影响很大,其每增大15°,轮胎的噪声声压将提高110%~130%。 展开更多
关键词 轮胎 噪声 数学模型 球面
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光纤点衍射干涉仪中球面参考源偏振控制系统的设计 被引量:2
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作者 代晓珂 金春水 +1 位作者 王丽萍 于杰 《光学学报》 EI CAS CSCD 北大核心 2014年第11期128-134,共7页
极紫外光刻光学检测通常使用光纤点衍射干涉仪,光纤衍射的圆偏振态光束可以提高干涉条纹的对比度、减小衍射球面波的像散,对于提高检测精度有十分重大意义。用穆勒矩阵分析了相位控制型偏振控制器的工作原理,得到只需两个控制通道就可... 极紫外光刻光学检测通常使用光纤点衍射干涉仪,光纤衍射的圆偏振态光束可以提高干涉条纹的对比度、减小衍射球面波的像散,对于提高检测精度有十分重大意义。用穆勒矩阵分析了相位控制型偏振控制器的工作原理,得到只需两个控制通道就可以调控到圆偏振态的结论。设计了光纤点衍射干涉仪球面参考源的偏振控制系统,并用琼斯矩阵分析了光束经过偏振控制系统后的光强变化,得到光强最小时两个控制通道的控制电压。在理论分析基础上搭建了球面参考源的偏振控制系统,获得了圆偏振态所需的控制电压,并将其输入偏振控制器调控得到圆偏振光,实验结果表明此方法可以在不引入额外误差的同时,快速地实现圆偏振态的调节,并且理论计算与实际的误差不超过7.5%,证明了该方法的可行性。 展开更多
关键词 光学设计 极紫外光刻 光纤点衍射 球面参考 偏振控制
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常用计量技术中光波干涉讲座(四) 光波干涉光路设立技巧及应用
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作者 李茂山 《实用测试技术》 2002年第2期38-42,共5页
本文讲述用于计量测试的光波干涉光路设立的一般方法和技巧。列举用白光串联干涉光路作定位原理以及用激光源球面波干涉环调整镜面平行 ,检测镜面间平行的原理。
关键词 计量测试 光波干涉光路设立 白光串联干涉光路 激光球面波干涉环
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基于空心球阵列的稳态声场重建
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作者 张学勇 李加力 +1 位作者 赵越 毛毅菲 《安徽建筑大学学报》 2023年第1期70-75,共6页
球形传声器阵列可有效重建三维空间声场,本文利用空心球形传声器阵列结合等效源方法开展声场重建研究。首先介绍球面等效源法声场重建方法,然后引入压缩感知算法,进一步提出基于压缩感知的球面等效源声场重建方法,最后利用单极子源对两... 球形传声器阵列可有效重建三维空间声场,本文利用空心球形传声器阵列结合等效源方法开展声场重建研究。首先介绍球面等效源法声场重建方法,然后引入压缩感知算法,进一步提出基于压缩感知的球面等效源声场重建方法,最后利用单极子源对两种方法进行声场重建数值仿真,分别探讨声源频率、声源位置、信噪比以及重建面半径对声场重建精度的影响。结果表明,基于空心球阵列的球面等效源法和压缩感知球面等效源法均可实现声场重建,压缩感知球面等效源法声场重建精度优于球面等效源法。 展开更多
关键词 球形传声器阵列 压缩感知 球面等效 近场声全息
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AVO Character Research of Natural Gas Hydrates in the East China Sea 被引量:1
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作者 LIU Huaishan HUANG Guangnan HE Yi TONG Siyou CUI Shuguo ZHANG Jin 《Journal of Ocean University of China》 SCIE CAS 2009年第3期270-276,共7页
Natural gas hydrates are considered as strategic resources with commercial potential in the 21st century. Obvious BSR characteristics will be shown on seismic profiles, if there exist natural gas hydrates. The AVO met... Natural gas hydrates are considered as strategic resources with commercial potential in the 21st century. Obvious BSR characteristics will be shown on seismic profiles, if there exist natural gas hydrates. The AVO method is one of the methods which can be used to identify and forecast lithologic characteristics and fluid properties by using the relationship between Amplitude and Offset. AVO anomaly is one of the significant signs to check out whether or not there is free gas below the BSR, so it can be used to detect natural gas hydrates from the seismic profile. Considering the geological and geophysical characteristics of the Okinawa Trough and making use of the techniques mentioned above, we can conclude that the conditions there are favorable for the formation and concentration of natural gas hydrates. By analyzing the data collected from the study area, one can discover many different anomalous phenomena on the seismic profile which are related to the existence of natural gas hydrates. Preliminary estimation of the natural gas hydrates in the Okinawa Trough shows that the trough is rich in natural gas hydrates and may become a potential important resources exploration area. 展开更多
关键词 natural gas hydrates free gas blank zone Okinawa Trough
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Reducing Heat-Load in Buildings through the Use of Solar Screens: Case Study of Bookshop House, Lagos
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作者 Adebamowo Michael Godwin John Oginni Adeyemi 《Journal of Civil Engineering and Architecture》 2012年第10期1435-1443,共9页
Technology advancement has ensured a better means of livelihood essentially in certain parts of West Africa, specifically Nigeria, where the climate is predominantly hot in most parts throughout the year. Air-conditio... Technology advancement has ensured a better means of livelihood essentially in certain parts of West Africa, specifically Nigeria, where the climate is predominantly hot in most parts throughout the year. Air-conditioning has reduced the harshness of indoor discomforts to the barest minimum. It is no more uncommon to find it regularly in use in most homes and offices. Currently, the economy has the centrality of its power supply hinged on generator plants. The enigma of the current situation is how this alternative problem has catastrophic after effects on the environment. This and many more add up to the greatest of all the threats now evading our environment and the world -- Global warming. The threat of Global warming is real and the need to find less environmentally destructive sources of energy cannot be overemphasized. This paper is a contribution towards energy saving in buildings through the reduction of solar radiation incident on buildings. Sustainable Building calls for an integrated planning approach for operating buildings economically, substantially reducing their impact on the environment by reducing energy/power consumption, amongst others, and enhancing the well-being of their inhabitants. Only buildings that reconcile all of the above factors are fit for the future. A case study of the CMS (Catholic Mission School) Book Shop house in Lagos was carried out. The methodology involved the use of a solar chart and shadow angle protractor to determine the overheated periods represented by the shading masks and data collected. From this analysis, it was decided to accept the use of external sun shading and preliminary designs and specifications were prepared by the architects. The use of external solar screens made a saving of up to 75% of the energy input which would otherwise have been required by air-conditioning. 展开更多
关键词 Heat load BUILDINGS solar screens energy savings shading masks
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Monitoring Local Impervious Surface Trends Using Indices Derived from Property Tax and Several Landsat Datasets
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作者 Marek Topolski 《Journal of Environmental Science and Engineering(A)》 2015年第6期311-328,共18页
Human economic and social needs can be in conflict with ecosystem needs. Land development increases impervious surfaces causing significant negative impacts to aquatic ecosystems. Many impervious surface estimates are... Human economic and social needs can be in conflict with ecosystem needs. Land development increases impervious surfaces causing significant negative impacts to aquatic ecosystems. Many impervious surface estimates are derived from remote sensing data, developed by using different methods and often out of date. Remote sensing data is often at scales applicable to regional management, but not local planning decisions. To date, no standardized annual dataset of percent impervious surface exists for use at both local and watershed scales. Effective communication between natural resource managers and local planners has been lacking. One solution is to monitor percent impervious surface with a relative index rather than direct measure. A relative index model can use a currency, like foundation square feet per hectare, which is useful for all decision makers. One data source for developing a relative index of impervious surface is property tax data. These data document annual land development at local scale. Here, the author presents the use of Maryland property tax data to index land development and percent impervious surface. 展开更多
关键词 Geographically weighted regression impervious surface LANDSAT MdProperty View relative index spatial analysis tax records.
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探测器平面上的注量率分布计算方法
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作者 熊华 范如玉 康克军 《清华大学学报(自然科学版)》 EI CAS CSCD 北大核心 2005年第3期392-395,共4页
注量率分布是球面源伽玛射线强度绝对测量的必需参数。通常使用的中心点公式只能用于探测器平面中心点注量率,而无法获得注量率分布。根据中心点公式,用微元法思想发展了一种计算任意点注量率的数值方法——Trueflux。计算表明:对中心点... 注量率分布是球面源伽玛射线强度绝对测量的必需参数。通常使用的中心点公式只能用于探测器平面中心点注量率,而无法获得注量率分布。根据中心点公式,用微元法思想发展了一种计算任意点注量率的数值方法——Trueflux。计算表明:对中心点,Trueflux与中心点公式一致;对任意点,Trueflux与MonteCarlo通用程序MCNP的结果在3%以内符合。因此,Trueflux是一种计算任意点注量率的有效方法。 展开更多
关键词 探测器 注量率 球面源 伽玛射线 MCNP
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