共查询到20条相似文献，搜索用时 15 毫秒
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V.S. Kulkarni 《Journal of The Franklin Institute》2008,345(1):29-38
The present paper deals with the determination of unknown temperature and thermal stresses on the upper surface of a thick circular plate. A thick circular plate is subjected to arbitrary known interior temperature under steady state. The fixed circular edge and lower surface of the circular plate are thermally insulated. The governing heat conduction equation has been solved by using Hankel transform methods. The results are obtained in series form in terms of Bessel's functions. The results for displacement and stresses have been computed numerically and illustrated graphically. 相似文献
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Chaotic attitude motion of a magnetic rigid spacecraft in a circular orbit near the equatorial plane
This paper deals with chaotic attitude motion of a magnetic rigid spacecraft in a circular orbit near the equatorial plane of the earth. The dynamical model of the problem is derived. The Melnikov analysis is carried out to prove the existence of a complicated nonwandering Cantor set. The dynamical behavior is numerically investigated by means of time history, Poincare map, power spectrum and Lyapunov exponents. Numerical simulations indicate that the onset of chaos is characterized by break of torus as the torque of the magnetic forces is increased. 相似文献
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Martijn Burger Spyridon Stavropoulos Shyaam Ramkumar Joke Dufourmont Frank van Oort 《Research Policy》2019,48(1):248-261
This paper examines the opportunities and risks of employment, skills and education that are related to a circular economy (CE) in the United States. Combining occupational skills and education data with a newly introduced definition of CE employment, we compare circular- and non-circular-oriented occupations in terms of skills and abilities. Building on the seminal paper by Consoli et al. (2016) and looking at all occupations within a broad range of CE-related industries, we detect and address heterogeneity in job requirements within the CE. We distinguish core activities within CE employment – focusing on renewable energy, repair, re-use of materials and the sharing economy – from enabling activities, which are focused on management, design, and ICT-applicability of the CE. While core CE-activities generally require more manual and technological skills, enabling activities, in contrast, require more complex cognitive skills. Neither core nor enabling CE sectors, however, are entirely cohesive in terms of skill requirements. Part of the education and skills demand is identifiably driven by ‘circularity’, particularly with regard to technical skills for the core of the CE. This may require specific education and training programs for future development of the CE. 相似文献
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《Information processing & management》2023,60(2):103147
The current study addresses the problem of retrieving a specific moment from an untrimmed video by a sentence query. Existing methods have achieved high performance by designing various structures to match visual-text relations. Yet, these methods tend to return an interval starting from 0s, which we named “0s bias”. In this paper, we propose a Circular Co-Teaching (CCT) mechanism using a captioner to improve an existing retrieval model (localizer) from two aspects: biased annotations and easy samples. Correspondingly, CCT contains two processes: (1) Pseudo Query Generation (captioner to localizer), aiming at transferring the knowledge from generated queries to the localizer to balance annotations; (2) Competence-based Curriculum Learning (localizer to captioner), training the captioner in an easy-to-hard fashion guided by localization results, making pairs of the false-positive moment and pseudo query become easy samples for the localizer. Extensive experiments show that our CCT can alleviate “0s bias” with even 4% improvement for existing approaches on average in two public datasets (ActivityNet-Captions, and Charades-STA), in terms of R@1,IoU=0.7. Notably, our method also outperforms baselines in an out-of-distribution scenario. We also quantitatively validate CCT’s ability to cope with “0s bias” by a proposed metric, DM. Our study not only theoretically contributes to detecting “0s bias”, but also provides a highly effective tool for video moment retrieval by alleviating such bias. 相似文献
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对一种亚毫米波频段的,缝隙型嵌套开口谐振环式频率选择表面(FSS)的极化转换特性进行了研究。通过仿真方法比较了开口环的缝隙长度、宽度、单元间距等参数的改变对谐振频率的影响,进而影响了频率选择表面的极化转换特性。通过优化,确定了频率选择表面的结构参数,得到了工作中心频率在427GHz,最大相位差为81.3度,低于3dB的轴比带宽为31.3%的频率选择表面圆极化器。 相似文献
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The purpose of this paper is to understand the hidden connection between Circular Economy (CE) and Industry 4.0 in the context of supply chain. The factors responsible for linking CE and Industry 4.0 are studied from two angles viz. from the enablers’ side and barriers’ side. In the paper, twenty-six significant enabling and fifteen challenging factors are identified which are further factorized using Principal Component Analysis (PCA). DEMATEL approach is applied on the factors constructed from PCA. Here, the DEMATEL is applied for three different sets of data termed as Optimistic, Pessimistic and Most Likely. The paper identified Artificial Intelligence, Service and Policy Framework, and Circular Economy are significant enablers connecting CE and Industry 4.0. Similarly, paper reports Interface Designing and Automated Synergy Model as the most significant challenges to link CE and Industry 4.0 in a supply chain. 相似文献
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In this research, linear and non-linear stability behaviour of a thin circular FGM plate subjected to the uniform temperature rise and the constant angular velocity loadings is analyzed. Properties of the FGM media are distributed across the thickness based on a power law form. Each property of the metal or ceramic constituents is considered to be the function of temperature based on the Touloukian model. General equilibrium equations for such conditions are obtained based on the classical plate theory. At first, the non-linear governing equations are established in a complete asymmetrical form. After that, two different analytical methods are presented to study the bifurcation behaviour. Existence of bifurcation phenomenon is examined. Pre-buckling analysis is performed for a plate with the immovable clamped edge. Stability equations are obtained based on the adjacent equilibrium criterion. The resulted equations are solved via the two distinct methodologies, i.e. the exact solution in terms of Coulomb wave functions and the power series method. A non-linear solution is also presented to detect the equilibrium path of the heated rotating FGM plate. It is found that the angular speed may stabilize the homogeneous circular plate which buckles during uniform heating. Furthermore, snapping may occur for FGM plates under the simultaneous action of heating and uniform rotation. 相似文献
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基于循环链的生态工业园区模式 总被引：9，自引：0，他引：9
生态工业园为可持续发展提供了概念性框架。通过对大量的案例进行分析，并根据废物一原料的转换关系，将生态工业园分为三类，分析了每类生态工业园都有各自的特点、资源利用效率、存在问题，最后对生态工业园的未来发展进行了展望。 相似文献
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The problem of minimizing the maximum temperature of a purely conducting circular fin with heat generation is studied via a variational technique. An exact solution is obtained for an arbitrary heat source distribution and a general non-linear heat conductivity. The problem of minimum weight design of convecting circular fin is then considered. An exact solution for temperature distribution and shape of the optimum fin with constant heat generation is obtained and discussed. 相似文献
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给出一种在圆迹合成孔径雷达模式下直接获取DEM的方法,将360°雷达平台轨迹圆环划分为多段圆弧,对每段圆弧分割为多个子孔径,利用子孔径图像间的相似性,通过相关系数最大法,在其他子孔径图像上寻找与中心图像匹配的像素点,得到二者的位置偏移,进而提取地面场景的DEM.最后,通过微波暗室实验验证了该方法的有效性. 相似文献