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CT图像的计算机制全息三维重建 总被引:1,自引:1,他引:0
提出用计算机制全息术实现CT图像的三维重建。首先研究了CT图像的三维信息融合,用计算机模拟CT图像的物光波,用菲涅耳计算全息图的方法,把CT图像的二维信息融合成三维信息,获得菲涅耳全息图。然后将计算机制全息与光学全息相结合,记录彩虹全息图。最后用扩展的白光再现,获得逼真无畸变的真正的三维立体图像,充分发挥了计算机制全息与光学全息的优势。在全息图的计算中利用了快速傅里叶算法,大大缩短计算时间。根据不同的观察需要制作了两种不同效果的全息图,并给出了理论分析和实验结果。 相似文献
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提出了一种新的计算全息标识证件防伪方法.该防伪方法首先通过计算机制作原始认证信息的菲涅耳加密面全息图,并变换成可印刷的全息标识,通过打印或数字印刷将其印制在证件等印刷品中作为防伪标识.原始认证信息的提取过程是加密过程的逆过程.理论分析和仿真实验证明了菲涅耳加密面全息标识方法的有效性和安全性. 相似文献
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提出了一种医学层析图像的计算全息三维可视化技术。首先研究了层析图像序列的三维信息融合,将层析图像序列的二维信息融合成三维信息,用计算全息图的方法进行三维信息记录。然后结合空间光调制器的结构特性,对全息系统的空间频率、参物光夹角、取样间隔以及全息再现像的再现区域和视角等进行了讨论和分析,并设置了相关参数,使计算全息系统与电子显示系统相匹配。最后用液晶空间光调制器作为全息图显示载体,用计算机控制全息图的实时输出,用雾屏承载三维空间再现像,建立三维图像光电再现与实时显示系统,实现层析图像序列的三维可视化,给出了理论分析与实验结果。 相似文献
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点源发出的低能量电子波经过样品的散射后,带有物体原子结构信息的散射波(物波)和未被散射的电子波(参考波)在收集平面上相互干涉形成的电子全息图即为低能电子投射全息图.本文在合理的物理模型下,以石墨的晶体结构为试样,通过计算机模拟的方法,首次对低能电子投射全息进行了研究,讨论了一些关键参数对晶体结构电子全息的重现像和分辨率的影响,并且实现了晶体结构三维数值重现,讨论了三维重现的效果. 相似文献
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声全息是著名的全息处理的一个特殊情况,它的全息图由相干声波产生。一旦把全息信息复制成光全息图以后,物波就能够用相干光来重现。这个方法在水声技术中的特殊问题是把声信息转换成一张适合重现的全息图。为了能够获得所希望的高方位分辨率,必须使用大孔径。因而,接收水听器系统一定要由大量的离散元组成。另一方面,因为接收信号极弱,所以每个水听器后面必须跟着它自己的单独的放大器,以便把它们的输出电压放大到足够高的电平。由于这些原因,水声信号全息接收器变得非常庞大。 相似文献
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原子的芯能级电子吸收能量后被激发 ,经过退激发过程发射出的俄歇电子波在传播过程中被周围的原子散射 ,带有周围原子结构信息的散射波 (物波 )与未被散射的电子波 (参考波 )相干涉形成的衍射图即俄歇电子全息图 ,通过全息图的重现 ,可获得原子级分辨率的三维结构信息。本文在合理的物理模型下 ,以Cu单晶以及高温超导YBCO中的Y原子近邻的一些原子簇为计算实例 ,首次就受激原子周围单层近邻原子散射和多层原子散射产生的俄歇电子全息进行了计算机模拟和数值重现 ,获得了三维晶格结构参量 ,并讨论了不同原子序数的原子在全息图形成及重现中的作用。本工作有助于材料微结构的研究 相似文献
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一、全息图复制技术
全息是指应用光的干涉和衍射原理,将物体发出的光波以涉条纹的形式记录下来成为“全息图”,并在一定的条件下再现出和原物逼真的三维衍射像的技术。由于记录了物体光波的振幅和相位信息,因而称为全息术或全息照相。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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The end of over unit products of more than Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits beer wine yellow wine fruit syrup wine others cover over % of the national top-branded liquor products.…… 《中国标准化(英文版)》2008,25(1):30
The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.…… 相似文献
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Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster. 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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N.A. Odintsova N.V. Ageenko K.V. Kiselev N.M. Sanina E.Y. Kostetsky 《International Journal of Refrigeration》2006,29(3):387
We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes. 相似文献
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David R. Smith F. R. Fickett 《Journal of research of the National Institute of Standards and Technology》1995,100(2):119-171
Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability. 相似文献