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961.
Peter K. Anastasovski T. E. Bearden C. Ciubotariu W. T. Coffey L. B. Crowell G. J. Evans M. W. Evans R. Flower S. Jeffers A. Labounsky D. Leporini B. Lehnert M. Mészáros J. K. Moscicki P. R. Molnár H. Múnera E. Recami D. Roscoe S. Roy 《Foundations of Physics Letters》1999,12(3):251-265
The general theory of gauge fields is used to develop a theory of electrodynamics in which the fundamental structure is non-Abelian and in which the internal gauge field symmetry is O(3), based on the existence of circular polarization and the third Stokes parameter. The theory is used to provide an explanation for the Sagnac effect with platform at rest and in motion. The Sagnac formula is obtained by considering the platform in motion to be a gauge transformation. The topological phases can be described straightforwardly with non Abelian electrodynamics, which produces a novel magnetic field component for all types of radiation, a component which is proportional to the third Stokes parameter. The theory provides a natural explanation for the inverse Faraday effect without phenomenology. 相似文献
962.
讨论等电子分子的分子 (电子数Ne=10 :HF ,H2 O ,NH3,CH4 ;Ne=14:N2 ,CO ,HCN ,C2 H2 ;Ne=18:HCl,CH3F ,H2 S ,SiH4 ,C2 H6)被电子散射的总截面与其键长、键角之间的关系 ,得到了利用键长、键角计算电子被分子散射总截面经验公式 ,并与已有的拟和公式、经验公式的计算结果进行了比较 相似文献
963.
从原料煤的均匀性、均匀性检验方法及判断标准、定值程序和定值方法、实验数据的统计处理、煤标准物质的稳定性等方面,介绍了研制动力煤标准物质的质量保证措施。 相似文献
964.
矩形板结构损伤的分区域神经网络识别方法 总被引:1,自引:1,他引:0
通过引入LM优化算法,针对矩形薄板中对称结构的损伤识别问题,提
出了一种基于神经网络的分区域分步识别方法. 对于预测输出量比较多且对预测精度要求比
较高的问题,常会出现网络训练时收敛速度慢、网络预测精度低,并且当网络训练达到目标
误差时,输出的预测量中常有某个输出量的误差还很大的情况. 针对这些问题,利用选
取的组合输入参数,提出了基于神经网络的分区域识别方法. 通过对悬臂板结构的数值模拟
结果表明:提出的分区域识别方法对结构损伤的分区和预测是可行和有效的,
其预测精度要明显的高于只用单个网络的预测结果,并且预测子网络对损伤的位置和程度是
同步输出的,从而避免了传统分步识别理论中子网络过多的问题. 相似文献
965.
芦氟沙星与牛血清白蛋白结合反应的热力学研究 总被引:2,自引:1,他引:2
用荧光光谱和紫外-可见吸收光谱法研究了在模拟人体生理条件下,芦氟沙星与牛血清白蛋白的结合反应,发现芦氟沙星对牛血清白蛋白有较强的荧光猝灭作用,用Stern-Volmer和Lineweaver-Burk方程处理荧光猝灭数据.得到了反应的结合常数、结合热力学性质和结合位置等参数. 相似文献
966.
P. Kolandaivel N. Suba K. Senthilkumar 《International journal of quantum chemistry》2000,76(5):662-669
Balint Kurti's Fourier grid Hamiltonian method is employed to obtain the molecular wave function and equilibrium bond length for H2 and HF molecules. The density functional theory parameter, namely, the chemical hardness (η) value, was determined for some diatomic hydride molecules using this wave function and the results are found to be in good agreement with the values obtained from the ab initio HF–SCF method. A new formula for chemical hardness (η=1/2Dr, where D is the proportionality constant and r is the internuclear distance) is introduced in binding energy and change of hardness equations to determine the chemical hardness and chemical potential values for different bond lengths. The binding energy and change of hardness values are calculated for H2, H, H, HF, HF+, and HF− molecules and the bond stability is discussed. Finally, the concept of an atom in a molecule is examined in the context of DFT parameters and comparison is made between an atom in a molecule and the isolated atom. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 76: 662–669, 2000 相似文献
967.
Muhammad Fawad Khan Muhammad Sulaiman Carlos Andrs Tavera Romero Ali Alkhathlan 《Entropy (Basel, Switzerland)》2021,23(11)
A unipolar electrohydrodynamic (UP-EHD) pump flow is studied with known electric potential at the emitter and zero electric potential at the collector. The model is designed for electric potential, charge density, and electric field. The dimensionless parameters, namely the electrical source number , the electrical Reynolds number , and electrical slip number , are considered with wide ranges of variation to analyze the UP-EHD pump flow. To interpret the pump flow of the UP-EHD model, a hybrid metaheuristic solver is designed, consisting of the recently developed technique sine–cosine algorithm (SCA) and sequential quadratic programming (SQP) under the influence of an artificial neural network. The method is abbreviated as ANN-SCA-SQP. The superiority of the technique is shown by comparing the solution with reference solutions. For a large data set, the technique is executed for one hundred independent experiments. The performance is evaluated through performance operators and convergence plots. 相似文献
968.
Sanjay Khan K. Sudhakar Mohd Hazwan Yusof Prof. Senthilarasu Sundaram 《Chemical record (New York, N.Y.)》2024,24(3):e202300308
The transition to sustainable transportation has fueled the need for innovative electric vehicle (EV) charging solutions. Building Integrated Photovoltaics (BIPV) systems have emerged as a promising technology that combines renewable energy generation with the infra-structure of buildings. This paper comprehensively reviews the BIPV system for EV charging, focusing on its technology, application, and performance. The review identifies the gaps in the existing literature, emphasizing the need for a thorough examination of BIPV systems in the context of EV charging. A detailed review of BIPV technology and its application in EV charging is presented, covering aspects such as the generation of solar cell technology, BIPV system installation, design options and influencing factors. Furthermore, the review examines the performance of BIPV systems for EV charging, focusing on energy, economic, and environmental parameters and their comparison with previous studies. Additionally, the paper explores current trends in energy management for BIPV and EV charging, highlighting the need for effective integration and recommending strategies to optimize energy utilization. Combining BIPV with EV charging provides a promising approach to power EV chargers, enhances building energy efficiency, optimizes the building space, reduces energy losses, and decreases grid dependence. Utilizing BIPV-generated electricity for EV charging provides electricity and fuel savings, offers financial incentives, and increases the market value of the building infrastructure. It significantly lowers greenhouse gas emissions associated with grid and vehicle emissions. It creates a closed-loop circular economic system where energy is produced, consumed, and stored within the building. The paper underscores the importance of effective integration between Building Integrated Photovoltaics (BIPV) and Electric Vehicle (EV) charging, emphasizing the necessity of innovative grid technologies, energy storage solutions, and demand-response energy management strategies to overcome diverse challenges. Overall, the study contributes to the knowledge of BIPV systems for EV charging by presenting practical energy management, effectiveness and sustainability implications. It serves as a valuable resource for researchers, practitioners, and policymakers working towards sustainable transportation and energy systems. 相似文献
969.
以室内三轴压缩试验为基础,运用PFC3D离散元软件生成含有不同形状碎石块的1∶1堆积碎石土数值模型,标定得到相应的细观参数(相对误差控制在10%以内)。改变细观参数,定量探讨其与宏观力学参数(粘聚力和内摩擦角)关系,得到细观参数与粘聚力、内摩擦角的细-宏观参数关系式,并对其可靠性进行了验证。研究发现,(1)粘聚力与接触粘结力、颗粒摩擦系数呈线性正相关;同时受粘结力比值M=σc/τc的影响,当M1时,粘聚力随着M的增加而线性增加;M≥4时,粘聚力趋于稳定。(2)内摩擦角与颗粒摩擦系数呈对数关系,与接触粘结力呈抛物线关系。(3)细-宏观参数关系式是在含水率为7%室内试验结果基础上研究得出,将关系式运用到含水率为9%和11%的室内试验结果进行标定验证:依据含水率为9%和11%室内试验得到的c和φ值,运用细-宏观参数关系式计算得到细观参数,经验证其数值-室内试验结果相对误差在10%以内,说明通过细-宏观力学关系式得到的细观参数符合精度要求,关系式可靠。为后续土石混合体数值试验研究者进行细观参数标定工作提供了参考依据。 相似文献
970.
Bruce L. Bush Christopher I. Bayly Thomas A. Halgren 《Journal of computational chemistry》1999,20(14):1495-1516
Bond-charge increments (BCIs) are additive parameters used to assign atomic charges for the MMFF force field. BCI parameters are classified parsimoniously according to two atom types and the bond order. We show how BCIs may be fitted rapidly by linear least squares to the calculated ab initio electrostatic potential (ESP) or to the electrostatic field. When applied simultaneously to a set of compounds or conformations, the method yields consensus values of the BCIs. The method can also derive conventional “ESP-fit” atomic charges with improved numerical stability. The method may be generalized to determine atom multipoles, multicenter charge templates, or electronegativities, but not polarizability or hardness. We determine 65 potential-derived (PD) BCI parameters, which are classified as in MMFF, by fitting the 6-31G* ESP or the electrostatic field of the 45 compounds in the original MMFF94 training set. We compare the consensus BCIs with classified BCIs that were fit to each molecule individually and with “unique-bond” BCIs (ESP-derived atom charges). Consensus BCIs give a satisfactory representation for about half of the structures and are robust to the adjustment of the alkyl CH bond increment to the zero value employed in MMFF94. We highlight problems at three levels: Point approximation: the potential near lone pairs on sulfur and to some extent nitrogen cannot be represented just by atom charges. Bond classification: BCIs classified according to MMFF atom types cannot represent all delocalized electronic effects. The problem is especially severe for bonds between atoms of equivalent MMFF type, whose BCI must be taken as zero. Consensus: discrepancies that occur in forming the consensus across the training set indicate the need for a more detailed classification of BCIs. Contradictions are seen (e.g., between acetic acid and acetone and between guanidine and formaldehydeimine). We then test the three sets of PD-BCIs in energy minimizations of hydrogen-bonded dimers. Unique-bond BCIs used with the MMFF buffered 14–7 potential reproduce unscaled quantum chemical dimer interaction energies within 0.9 kcal/mol root mean square (or 0.5, omitting two N-oxides). These energies are on average 0.7 (or 0.5) kcal/mol too weak to reproduce the scaled quantum mechanical (SQM) results that are a benchmark for MMFF parameterization. Consensus BCIs tend to weaken the dimer energy by a further 0.4–0.6 kcal/mol. Thus, consensus PD-BCIs can serve as a starting point for MMFF parameterization, but they require both systematic and individual adjustments. Used with a “harder” AMBER-like Lennard–Jones potential, unique-bond PD-BCIs without systematic adjustment give dimer energies in fairly good agreement with SQM. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1495–1516, 1999 相似文献