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51.
A boundary integral equation method is applied to the study of the interaction of plane elastic waves with a periodic array
of collinear inplane cracks. Numerical results are presented for the dynamic stress intensity factors. The effects of the
wave type, wave frequency, wave incidence angle, and crack spacing on the dynamic stress intensity factors are analyzed in
detail.
The project supported by the Committee of Science and Technology of Shanghai and Tongji University 相似文献
52.
53.
S. I. Martynov 《Fluid Dynamics》2002,37(6):889-895
Viscous flow past an infinite periodic array of rigid spheres is considered. The hydrodynamic interaction of all the particles in the array is taken into account. An analytical solution of the problem is proposed. The forces exerted by the fluid on the array particles are calculated and an expression for the velocity of fluid filtration through the array is obtained. The results are compared with the previous theoretical and experimental results. 相似文献
54.
55.
优化超声变幅杆的形状结构可有效地提高水域声场分布和空化区域,提升对水域超声空化效果。通过模拟分析发现传统超声变幅杆在水域中具有声场分布均匀性差、变幅杆端部声压高等特征,不利于声波在水域中传播。基于此,提出并优化设计了一种具有碟形结构的变幅杆,位于变幅杆的最大振幅处的碟形结构,有更大的振动位移;模拟表明其水域声场和声压均衡度显著优于传统变幅杆,铝箔空化腐蚀实验进一步证实了其水域中的声压分布均匀性。同时,实验通过铝箔的空化腐蚀、KI剂量测定及工件表面油渍去除对比了传统变幅杆和碟形变幅杆,分析表明碟形变幅杆所在水域中有较大的空化腐蚀区域,腐蚀速率明显提升,声化学反应速率提高,油渍去除程度增强,说明了设计的碟形变幅杆能够促进空化泡的产生,增加水域空化区域。 相似文献
56.
为了探究超声搅拌磁流变抛光液的制备及优化工艺,利用多物理场数值计算方法,建立了超声搅拌磁流变抛光液的声场仿真模型,并进行了频域分析。研究了不同液位深度、超声变幅杆探入深度,不同功率下磁流变抛光液的声场分布。通过测量磁流变抛光液的声场强度对声场仿真进行了验证。结果表明:随着距变幅杆距离的增加,声强逐渐减弱,高声强区域主要分布在换能器轴线附近。声强在距变幅杆20mm范围内急剧衰减,变幅杆最佳探入深度为10mm,增大功率有助于空化区域的扩大。声场仿真结果与实验测量结果基本一致,对磁流变抛光液的制备提供了数值计算基础。 相似文献
57.
Maria Francesca Alberghina Patrizia Capizzi Salvatore Schiavone Silvestro Antonio Ruffolo Valeria Comite 《Natural product research》2019,33(7):1034-1039
AbstractStructural analysis of marble statues, carried out by non-invasive and in situ methods, is crucial to define the state of conservation of the artworks and to identify the deterioration phenomena that can affect them. In this work, we combined in situ non-destructive techniques, ultrasonic tomography (US), ultraviolet-induced visible fluorescence (UV-IF) and X-ray fluorescence (XRF) to study the bass-relief ‘Madonna con Bambino’ (Gorizia, Italy). The US revealed the presence of some metallic pivots, associated with areas of high sound velocity; moreover, a more degraded area has been identified in the lower part of the bass-relief. The acquired UV-IF image confirmed the presence of surface degradation, allowing a preliminary evaluation of the extension of a fracture, from surface to bulk. In addition, the different materials (both original and/or integrations) that compose the studied surface have been identified. The XRF has contributed to define the nature of the inorganic materials applied during undocumented previous restoration works on the surface as filler for lacunae. 相似文献
58.
《Physics letters. A》2020,384(26):126199
In the present work, high quality Pb doped ZnS thin films were deposited on glass substrates at 450°C using spray ultrasonic technique. The dependence of the structural, morphological and optical properties of the films on the lead (Pb) doping amount was investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis–NIR spectrophotometry, and four-point method. The improvement of the obtained Pb:ZnS thin films properties were discussed as a function of Pb concentration (0.5 to 2 at.%). The average crystallite size of Pb:ZnS was found in the range of 25–37 nm. The scanning electron microscopy (SEM) reveals that the films are continuous, homogeneous and dense. The UV–vis–NIR spectroscopy characterizations demonstrated that all the films exhibit good transmittance (60–70%) in the visible region and their optical band gap energy () changes from 3.92 to 3.6 eV. The films electrical resistivity showed an apparent dependence on Pb content. 相似文献
59.
Back Cover: Ultrasound‐Driven Secondary Self‐Assembly of Amphiphilic β‐Cyclodextrin Dimers (Chem. Eur. J. 13/2015) 下载免费PDF全文
60.
Combining Organometallic Reagents,the Sulfur Dioxide Surrogate DABSO,and Amines: A One‐Pot Preparation of Sulfonamides,Amenable to Array Synthesis 下载免费PDF全文
Alex S. Deeming Dr. Claire J. Russell Prof. Michael C. Willis 《Angewandte Chemie (International ed. in English)》2015,54(4):1168-1171
We describe a method for the synthesis of sulfonamides through the combination of an organometallic reagent, a sulfur dioxide equivalent, and an aqueous solution of an amine under oxidative conditions (bleach). This simple reaction protocol avoids the need to employ sulfonyl chloride substrates, thus removing the limitation imposed by the commercial availability of these reagents. The resultant method allows access to new chemical space, and is also tolerant of the polar functional groups needed to impart favorable physiochemical properties required for medicinal chemistry and agrochemistry. The developed chemistry is employed in the synthesis of a targeted 70 compound array, prepared using automated methods. The array achieved a 93 % success rate for compounds prepared. Calculated molecular weights, lipophilicities, and polar surface areas are presented, demonstrating the utility of the method for delivering sulfonamides with drug‐like properties. 相似文献