基于Matlab的RLC二阶电路零输入响应的研究

应用Matalb软件对RLC串联放电二阶电路的零输入响应进行了深入分析，给出了在3种情况下脉冲放电电流峰值im与R、L、C等参数的函数关系，用计算和绘图方法证明了在两种情况下不同形式的im=f(R、L、C）及i=f(t)、uc=f(t）等函数式的一致性，介绍了用能量平衡求该电路im值的方法。     

强电流脉冲控制的永磁起重吸盘研究与设计

介绍了永磁起重吸盘的工作原理及相对于传统电磁铁的节能、省材、廉价、安全等特点，讨论了应用电容储能经RLC串联二阶电路放电产生的强电流脉冲对永磁体进行充、退磁的方法及涡流问题，给出了一种控制电路及实验结果。     

基于认知语言学解释英语名词词组的多重前置修饰语语序

名词词组是指以一个名词为核心词(Head Noun)为中心,在其前面或后面加上修饰词而组成的名词性词组。其中以多重前置修饰语结构的名词词组(multi-pre-modification noun phrase,简称MP-NP)最为难理解。本文基于认知语言学的理论框架,从"概念化",范畴化",识解过程"等方面对MP-NP语序进行解释,揭示出MP-NP结构的人类体验基础。     

一种改进的基于秩检测的信道有效阶数估计算法

信道阶数估计是SOS类盲辨识算法的前端步骤。针对Liavas阶数估计算法对信噪比要求高的问题,通过对接收序列自相关矩阵进行"降噪"处理和改进秩检测目标函数,提出一种改进算法,有效降低了对信噪比的要求。分析了在不同信道条件下,各种阶数估计算法的性能,阐明随着信噪比降低,阶数估计误差不可避免,该结论是进一步研究对阶数估计误差鲁棒的盲辨识算法的重要依据。     

高浓度颗粒气固两相流动的二阶矩模型的数值模拟

采用动理学方法,用各向异性的M axwell颗粒速度分布函数,建立颗粒相Boltzm ann方程,分别取零次矩、一次矩和二次矩得到颗粒相连续方程、动量方程和二阶矩方程.模拟计算得到上升管内颗粒流场分布和脉动速度分布,与实验结果比较表明:各向异性颗粒动理学能够反映颗粒流动特性,从而能够更全面地认识高颗粒浓度气固两相流动过程.     

Reduced basis method for managed pressure drilling based on a model with local nonlinearities

To circumvent restrictions of conventional drilling methods, such as slow control actions and inability to drill depleted reservoirs, a drilling method called managed pressure drilling (MPD) has been developed. In MPD, single-phase flow processes can be modeled as a feedback interconnection of a high-order linear system and a low-order nonlinear system. These nonlinearities appear locally both inside and at the boundaries of the computational domain. To obtain a fast simulation platform for real-time purposes (eg, online model-based controller implementation), model order reduction is required for MPD. However, the local nonlinearities render applying model order reduction techniques challenging. In this study, a new approach is proposed to deal with such nonlinearities within the reduced basis (RB) context and it is successfully tested on a model for MPD. Contrary to the classical RB technique, the proposed approach not only does not generate nonphysical spikes at the locations of these local nonlinearities but also yields high speedup factors. The obtained reduced-order model can be used for efficient online simulation and controller design for drilling systems with MPD.     

Efficient geometrical parametrization for finite-volume-based reduced order methods

In this work, we present an approach for the efficient treatment of parametrized geometries in the context of proper orthogonal decomposition (POD)-Galerkin reduced order methods based on finite-volume full order approximations. On the contrary to what is normally done in the framework of finite-element reduced order methods, different geometries are not mapped to a common reference domain: the method relies on basis functions defined on an average deformed configuration and makes use of the discrete empirical interpolation method to handle together nonaffinity of the parametrization and nonlinearities. In the first numerical example, different mesh motion strategies, based on a Laplacian smoothing technique and on a radial basis function approach, are analyzed and compared on a heat transfer problem. Particular attention is devoted to the role of the nonorthogonal correction. In the second numerical example, the methodology is tested on a geometrically parametrized incompressible Navier-Stokes problem. In this case, the reduced order model is constructed following the same segregated approach used at the full order level.     

Calculating the Reaction Order and Activation Energy for the Hydrothermal Carbonization of Fructose

The development of accurate kinetic models for hydrothermal carbonization (HTC) faces major difficulties. This is related to the fact that the formation of the solid hydrochar can be regarded as a formation of a second phase from a homogenous solution. The reaction mechanism is not fully understood. From the current state of art, it is obvious that the reaction mechanism is some sort of polymerization reaction, thus, having reaction order higher than one. In order to gain more knowledge about the HTC reaction, fructose is used as a model substance, as it can be regarded as a key intermediate during the hydrothermal processing of carbohydrates. The results indicate that the reaction order is a highly sensitive parameter varying with temperature, reaction time and initial concentration. It can be concluded that the model itself is a strong simplification of the real reaction mechanism, thus more research is necessary to complete the actual knowledge.     

Layered-Perovskite Nanowires with Long-Range Orientational Order for Ultrasensitive Photodetectors

2D layered metal-halide perovskites combine efficient exciton radiative recombination in crystal interior with long-distance free-carrier conduction at layer edges, which are promising candidates for realizing high-performance photovoltaic, light-emission and photodetection devices. The anisotropic electrical conductivity in layered perovskites imposes an additional requirement of orientational control for enabling favorable charge transport. However, rational fabrication of single-crystalline nanostructures with pure crystallographic orientation is still elusive. Herein, large-scale pure (101)-orientated 2D-perovskite single-crystalline nanowire arrays are realized by combining solvent engineering with the capillary-bridge lithography technique. Ordered nucleation at liquid–air interface and unidirectional growth along the dewetting direction are demonstrated by fluorescence microscopy and grazing-incidence X-ray scattering in discrete capillary bridges. In consideration of crystal interior exhibiting high resistance arising from the serial insulating organic barriers and ultrafast dissociation of excitons to generate long-lived free carriers at layer edges, ultrasensitive photodetectors are demonstrated with average responsivity exceeding 1.1 × 10⁴ A W⁻¹ and detectivity exceeding 9.1 × 10¹⁵ Jones.     

C语言程序设计教学方法探讨

越来越多的大学开设了C语言作为计算机程序设计类基础课程 ,C语言程序设计基本概念和能力已成为学习后序计算机课程的重要基础。文章根据实践教学经验 ,总结分析了c语言程序设计课程教学中的一些教学方法 ,并结合实际案例进行了说明。希望能给大学计算机基础教学提供一些参考方法