基于Griffith强度理论的空腔膨胀模型与应用研究

根据混凝土材料受高速冲击时产生大量碎裂的特点,假设其粉碎(塑性)区介质服从Griffith 强度理论,发展了弹丸深侵彻混凝土靶的动态空腔膨胀模型,建立了弹丸深侵彻理论计算公 式. 对比表明：基于Griffith强度理论的球形动态空腔膨胀模型的计算结果与实验数据吻合 较好.     

A Deep Neural Network Method for Arterial Blood Flow Profile Reconstruction

Arterial stenosis will reduce the blood flow to various organs or tissues, causing cardiovascular diseases. Although there are mature diagnostic techniques in clinical practice, they are not suitable for early cardiovascular disease prediction and monitoring due to their high cost and complex operation. In this paper, we studied the electromagnetic effect of arterial blood flow and proposed a method based on the deep neural network for arterial blood flow profile reconstruction. The potential difference and weight matrix are used as inputs to the method, and its output is an estimate of the internal blood flow velocity distribution for arterial blood flow profile reconstruction. Firstly, the weight matrix is input into the convolutional auto-encode (CAE) network to extract its features. Then, the weight matrix features and potential difference are combined to obtain the features of the blood velocity distribution. Finally, the velocity features are reconstructed into blood flow velocity distribution by a convolution neural network (CNN). All data sets are obtained from a model of the carotid artery with different rates of stenosis in a uniform magnetic field by COMSOL. The results show that the average root mean square error of the reconstruction results obtained by the proposed method is 0.0333, and the average correlation coefficient is 0.9721, which is better than the corresponding indicators of the Tikhonov, back propagation (BP) and CNN methods. The simulation results show that the proposed method can achieve high accuracy in blood flow profile reconstruction and is of great significance for the early diagnosis of arterial stenosis and other vessel diseases.     

21世纪核物理发展前沿探讨

评述了对下个世纪核物理发展前景的两种看法 ,详细分析了 2 1世纪核物理学将发生的巨大变革,以及核物理学家面临的新挑战与新机遇.Different opinions about prospects of the development of nuclear physics in the 21st century are displayed, and indicating great opportunities and challenges faced by nuclear physicists in the future are analyzed in detail.     

Deep Oxidation of Methane Over Manganese Oxide Modified by Mg, Ca, Sr and Ba Additives

Manganese oxide catalysts modified by Mg, Ca, Sr and Ba additives were studied for methane deep oxidation. The Ba promoted sample is the most effective one for this reaction among all the catalysts. The catalysts were examined by BET, XRD and H₂-TPR techniques. It is speculated that the formation of some more active oxygen species and the formation of basic sites from the addition of alkaline earth metal oxides are responsible for the improvement of the inherent CH₄ oxidation activity of the modified catalysts.     

Nonlinear finite element analyses of concrete bridge joint systems subjected to seismic actions

Following widespread damage to bridge joints in the San Francisco region from the 1989 Loma Prieta earthquake, the necessity for establishing an alternative method for seismic design of bridge joints was identified. Recognizing that conventional joint design practice based directly on shear forces results in congested reinforcement details, which are difficult to implement in practice, a rational design procedure was sought through large-scale testing of bridge joint systems and subsequent finite element and strut-and-tie analyses. The finite element part of the study is presented in this paper, which focuses on (a) identification of compression force flow and thus the load path across the joint, (b) examination of an efficient joint force transfer model, and (c) influence of cap beam prestressing. Combining the experimental and analytical results, a joint design method has been established in which reduction of joint reinforcement was achieved by treating joint shear as part of the complete force transfer across the joint, rather than as an independent action. The proposed design approach has been validated in a laboratory test on a full-scale multiple-column bridge bent.     

偏压隧道二次应力场分析及应用

详细分析了倾斜地表下岩体的应力状态,通过分解叠加的等效原则解出一般条件下围岩的二次应力解析解,并探讨该应力场的特性,结合黄土岭隘道工程,将解析值与实测数据进行对比分析,理论分析与实测结果符合良好。     

Deep Eutectic Solvents in Solar Energy Technologies

Deep Eutectic Solvents (DESs) have been widely used in many fields to exploit their ecofriendly characteristics, from green synthetic procedures to environmentally benign industrial methods. In contrast, their application in emerging solar technologies, where the abundant and clean solar energy is used to properly respond to most important societal needs, is still relatively scarce. This represents a strong limitation since many solar devices make use of polluting or toxic components, thus seriously hampering their eco-friendly nature. Herein, we review the literature, mainly published in the last few years, on the use of DESs in representative solar technologies, from solar plants to last generation photovoltaics, featuring not only their passive role as green solvents, but also their active behavior arising from their peculiar chemical nature. This collection highlights the increasing and valuable role played by DESs in solar technologies, in the fulfillment of green chemistry requirements and for performance enhancement, in particular in terms of long-term temporal stability.     

Novel Binary Mixtures of Alkanolamine Based Deep Eutectic Solvents with Water—Thermodynamic Calculation and Correlation of Crucial Physicochemical Properties

This paper demonstrates the assessment of physicochemical and thermodynamic properties of aqueous solutions of novel deep eutectic solvent (DES) built of tetrabutylammonium chloride and 3-amino-1-propanol or tetrabutylammonium bromide and 3-amino-1-propanol or 2-(methylamino)ethanol or 2-(butylamino)ethanol. Densities, speeds of sound, refractive indices, and viscosities for both pure and aqueous mixtures of DES were investigated over the entire range of compositions at atmospheric pressure and T = (293.15 ‒ 313.15) K. It was concluded that the experimental data were successfully fitted using the Jouyban–Acree model with respect to the concentration. Obtained results showed that this mathematical equation is an accurate correlation for the prediction of aqueous DES properties. Key physicochemical properties of the mixtures—such as excess molar volumes, excess isentropic compressibilities, deviations in viscosity, and deviations in refractive indices—were calculated and correlated by the Redlich–Kister equation with temperature-dependent parameters. The non-ideal behavior of the studied systems were also evaluated by using the Prigogine−Flory−Patterson theory and the results were interpreted in terms of interactions between the mixture components.     

超深亚微米PMOS器件的NBTI退化机理

对超深亚微米PMOS器件的负栅压温度不稳定性(NBTI)退化机理进行了研究.主要集中在对器件施加NBT和随后的PBT应力后器件阈值电压的漂移上.实验证明反型沟道中空穴在栅氧中的俘获以及氢分子在栅氧中的扩散是引起NBTI退化的主要原因.当应力条件变为PBT时，陷落的空穴可以快速退陷，但只有部分氢分子可以扩散回栅氧与衬底界面钝化硅悬挂键，这就导致了PBT条件下阈值电压只能部分恢复. 关键词： 超深亚微米PMOS器件 负偏压温度不稳定性 界面陷阱 氢气     

深空探测自主导航技术综述

深空探测自主导航技术在减少地面测控负担, 提高探测器的生存能力和扩展探测器的特殊应用潜力等方面具有独特的优势, 自主导航在国外的深空探测活动中已经成功验证并逐步开始在实际任务中应用, 未来的自主导航技术将成为深空探测技术发展的一种必然趋势. 由于我国测控资源有限, 在我国的深空探测规划中, 发展自主导航技术将显得更为重要. 在我国即将开展火星和小行星探测计划的背景下, 本文综述了国外深空探测自主导航技术研究状况, 以及在一些探测任务中的试验和应用情况, 并对每个探测活动进行了简要概括;其次, 本文调研了国外自主导航系统中所采用的光学敏感器设备;最后, 结合"深空1号"任务巡航段基于小行星的光学自主导航, 分析提出了深空探测自主导航中需要掌握的关键技术, 并对相应的技术在国内外研究情况进行了总结.