Soret and MHD effects on bioconvection wall jet flow of nanofluid containing gyrotactic microorganisms

Various applications of bioconvection phenomena in the field of medicine and biotechnology boost us to present the study of laminar wall jet flow in this specific direction. For the purpose, we have considered nanofluid containing gyrotactic microorganisms in the presence of normally applied magnetohydrodynamic forces along with Soret effects. Boundary layer approximation and similarity transformation are utilized to convert governing equations into ordinary differential equations. Influence of different emerging parameters on velocity, temperature and concentration profiles of solute, nanoparticle and motile microorganisms has been investigated. The role of physical quantities like Nusselt number, Sherwood number and density number of microorganisms is also highlighted. Increase in Nusselt number and density number of motile microorganism is observed for incremental values of bioconvection Peclet number. Soret number reflects increasing effect on Nusselt number and decreasing effect on Sherwood number because solute diffusion faces resistance due to higher values of Soret number and in return decreases rate of mass transfer. Also bioconvection Rayleigh number imposes decreasing effect on density number of the motile microorganisms.

     

微结构固体中孤立波的动力学稳定性

描述微结构固体中波传播的一种KdV类方程作为控制方程并利用积分因子方法,对微结构固体中传播的孤立波的动力学稳定性进行了数值模拟研究。主要以高斯波、Ricker子波以及双曲正割波作为初始扰动,考察了不同小扰动下孤立波能否较长时间保持波形结构和传播速度而稳定传播问题。模拟结果表明,不同的小扰动对孤立波的影响不同,孤立波的稳定传播与扰动幅度和宽度都有关系,只有受到幅度和宽度都非常小的扰动下在微结构固体中传播的孤立波才能显现出一定程度的抗干扰性和动力学稳定性,可在微结构固体中较长时间稳定传播。     

Pattern search algorithms for nonlinear inversion of high-frequency Rayleigh-wave dispersion curves

Inversion of Rayleigh wave dispersion curves is challenging for most local-search methods due to its high nonlinearity and to its multimodality. In this paper, we implemented and tested a Rayleigh wave dispersion curve inversion scheme based on GPS Positive Basis 2N, a commonly used pattern search algorithm. Incorporating complete poll and complete search strategies based on GPS Positive Basis 2N into the inverse procedure greatly enhances the performance of pattern search algorithms because the two steps can effectively locate the promising areas in the solution space containing the global minima and significantly reduce the computation cost, respectively.The proposed inverse procedure was applied to nonlinear inversion of fundamental-mode Rayleigh wave dispersion curves for a near-surface shear (S)-wave velocity profile. The calculation efficiency and stability of the inversion scheme are tested on three synthetic models and a real example from a roadbed survey in Henan, China. Effects of the number of data points, the reduction of the frequency range of the considered dispersion curve, errors in P-wave velocities and density, the initial S-wave velocity profile as well as the number of layers and their thicknesses on inversion results are also investigated in the present study to further evaluate the performance of the proposed approach.Results demonstrate that pattern search algorithms applied to nonlinear inversion of high-frequency surface wave data should be considered good not only in terms of accuracy but also in terms of the computation effort due to their global and deterministic search process.     

New lower bounds based on column generation and constraint programming for the pattern minimization problem

The pattern minimization problem is a cutting and packing problem that consists in finding a cutting plan with the minimum number of different patterns. This objective may be relevant when changing from one pattern to another involves a cost for setting up the cutting machine. When the minimization of the number of different patterns is done by assuming that no more than the minimum number of rolls can be used, the problem is also referred to as the cutting stock problem with setup costs.     

三维海浪造型的研究

为了表现海浪的真实感和实时性仿真,本文以Pierson．Moskowitz模型为基础,采用波的波长和波速建立了海浪波高的初始状态值．通过FBM（FractalBrownMotion）的菱形网格方式计算海浪曲面片上每个网格点的波高,把每个点画出;再以菱形网格模拟海浪形状,将海浪点的波高描述为随时间和空间变化的多个正弦波叠加近似地表现海浪的运动效果;利用光照模型给海浪添加明暗凹凸效果,增加海浪的真实感;将真实世界中某一海浪的图像作为纹理源,贴到每个网格上,提高仿真的逼真度和运行速度,达到实时仿真的效果．利用Java和JOGL编程模拟,逼真地生成了海浪在不同风向、不同等级情况下的场景．实验表明文中所述方法得当,技术可行．     

用MATLAB分析无缝线路的稳定性

应用MATLAB语言对无缝线路稳定性的变形波长短于初始波长的不等波长波形计算公式进行了编程,并进行了不同参数的计算,计算过程快捷、精确度高,具有很强的实用性。     

多模态动态核主成分分析的气液两相流状态监测

气液两相流流动过程作为一种非平稳过程,其状态的变化具有时变性、非线性、随机性等复杂流动过程的特点,其流动状态的实时监测对掌握其流动过程的产生、发展及转化,保障实际生产的安全稳定运行具有重要意义.特别是流动状态的过渡过程反映了流动状态的发展及演化,其流动结构非常复杂.针对气液两相流的3种典型流动状态及过渡转化过程,在多传...     

线列传声器方向性研究

线列传声器的核心构件是由压电陶瓷圆环作换能元件的一个线列阵,阵元间距小于四分之一波长。建立了传声器方向性函数的表达式,分析了影响方向性图的各个因素,结果表明它具有明显的超指向性和恒定束宽特性。给出了线列传声器几种重要的方向性图及其相应条件。通过对传声器模型所作的试验表明,理论分析与实验数据结果基本上是一致的。本文所提出的技术可使一个传声器能具有不同的方向特性,满足不同使用条件的要求,并且传声器具有结构简单,坚固耐用,性能稳定的优点。     

An algorithm for the determination of optimal cutting patterns

This paper presents a new mathematical programming formulation for the problem of determining the optimal manner in which several product rolls of given sizes are to be cut out of raw rolls of one or more standard types. The objective is to perform this task so as to maximize the profit taking account of the revenue from the sales, the costs of the original rolls, the costs of changing the cutting pattern and the costs of disposal of the trim. A mixed integer linear programming (MILP) model is proposed which is solved to global optimality using standard techniques. A number of example problems, including an industrial case study, are presented to illustrate the efficiency and applicability of the proposed model.Scope and purposeOne-dimensional cutting stock (trim loss) problems arise when production items must be physically divided into pieces with a diversity of sizes in one dimension (e.g. when slitting master rolls of paper into narrower width rolls). Such problems occur when there are no economies of scale associated with the production of the larger raw (master) rolls. In general, the objectives in solving such problems are to [5]:

• •minimize trim loss;
• •avoid production over-runs and/or;
• •avoid unnecessary slitter setups.

The above problem is particularly important in the paper converting industry when a set of paper rolls need to be cut from raw paper rolls. Since the width of a product is fully independent of the width of the raw paper a highly combinatorial problem arises. In general, the cutting process always produces inevitable trim-loss which has to be burned or processed in some waste treatment plant. Trim-loss problems in the paper industry have, in recent years, mainly been solved using heuristic rules. The practical problem formulation has, therefore, in most cases been restricted by the fact that the solution methods ought to be able to handle the entire problem. Consequently, only a suboptimal solution to the original problem has been obtained and very often this rather significant economic problem has been left to a manual stage. This work presents a novel algorithm for efficiently determining optimal cutting patterns in the paper converting process. A mixed-integer linear programming model is proposed which is solved to global optimality using available computer tools. A number of example problems including an industrial case study are presented to illustrate the applicability of the proposed algorithm.     

基于毫米波雷达的智能车辆纵横向主动避障控制系统设计

智能车辆所搭载监测设备对障碍物目标的识别准确性,影响行驶车辆的纵横向避障能力。为避免车辆与障碍物发生碰撞,提升智能车辆的纵横向避障能力,设计基于毫米波雷达的智能车辆纵横向主动避障控制系统。在底层控制单元中,按需连接纵横向导航控制元件与毫米波雷达摄像头,完成智能车辆纵横向主动避障控制系统的部件结构设计。利用毫米波雷达监测所得的车辆避障图像,定义空间坐标系转换条件,通过标定雷达相机参数的方式,实现基于毫米波雷达的智能车辆避障路径规划。建立车辆纵横向运动模型,根据避障安全距离计算结果,完善具体控制流程,联合各级硬件应用结构,完成基于毫米波雷达的智能车辆纵横向主动避障控制系统的设计。实验结果表明,所设计系统可在智能车辆通过障碍物目标时,保证车体与障碍物之间的距离大于0.3m,能够避免碰撞行为发生,对于车载监测设备而言,其对于障碍物目标的准确识别能力得到了保障,能够有效提升智能车辆纵横向避障能力。     

微结构固体中孤立波的动力稳定性

描述微结构固体中波传播的一种KdV类方程作为控制方程并利用积分因子方法,对微结构固体中传播孤立波的动力学稳定性进行了数值模拟研究.主要以高斯波、Ricker子波以及双曲正割波扰动作为初始扰动,考察了不同小扰动下孤立波能否较长时间保持波形结构和传播速度而稳定传播问题.结果表明,不同的小扰动对孤立波的影响不同,孤立波的稳定...     

涡激振动行波动力学特征的数值模拟

采用数值模拟分析了水中大长径比结构物涡激振动行波动力学特征,以及水动力学阻尼和模型初始张力对于行波动力学特征的影响.数值模拟模型采用改进的尾流振子模型,该模型考虑了涡激振动横向运动和顺流向运动之间的耦合,考虑了张力沿模型长度的变化和流体的耗散.给出了用于评估行波在整个振动波中所占比例的方法,该方法采用行波椭圆来定量表征行波所占的比例,即行波比.数值模拟结果显示,行波比总体上呈现随流速增加的趋势,但在模态阶数变化的临界流速上突然降低.水动力学阻尼显著影响着行波比,阻尼比越大,行波比越大,行波对于整个振动波的贡献就越大.不同张力情况下,行波比突然下降的临界速度不同.初始张力影响模型的固有频率,影响模态阶数发生转变的流速,从而影响了行波比突然下降的临界流速.     

A note on pattern reproduction in tessellation structures

Tessellation structures that reproduce arbitrary patterns are special cases of tessellation structures having local transformations that are linear operators. We introduce a novel formulation of tessellation structures which emphasizes the connection between these structures and concepts of functional analysis. Using this formulation a behavioral analysis technique is developed which implies the earlier results on pattern reproduction and generalizes them to tessellation structures whose state alphabets are arbitrary fields of non-zero characteristic and whose tessellation arrays are arbitrary countable abelian groups. It is also shown that a local transformation can be chosen to produce at a specified time any desired set of “copies” of an initial pattern each multiplied by a specified scalar. We then indicate that connections exist between linear tessellation structures and linear partial differential equations which describe wave propagation by giving an example of a classical form of pattern reproduction.     

High-resolution satellite measurements of coastal wind field and sea state

Methods to derive wind speed and sea state by simple empirical models from synthetic aperture radar (SAR) data are presented and applied for use in high-resolution numerical modelling for coastal applications. The new radar satellite, TerraSAR-X (TS-X), images the surface of the sea with a high resolution up to 1 m. Therefore, not only wind information and integrated sea state parameters but also individual ocean waves with wavelengths down to 30 m are detectable. Two-dimensional information on the ocean surface retrieved using TS-X data is validated for different oceanographic applications: derivation of finely resolved wind fields (XMOD algorithm) and integrated sea state parameters (XWAVE algorithm). Both algorithms are capable of taking into account fine-scale effects in coastal areas. Wind and sea state information retrieved from SAR data are applied as the input for a wave numerical spectral model (wind forcing and boundary condition) running at a fine spatial horizontal resolution of 100 m. Results are compared to collocated buoy measurements. Studies are carried out for varying wind speeds and comparisons against wave height, simulated using original TS-X-derived wind data, showing the sensitivity of waves to local wind variation and thus the importance of local wind effects on wave behaviour in coastal areas. Examples for the German Bight (North Sea) are shown. The TS-X satellite scenes render well-developed ocean wave patterns of developed swell at the sea surface. Refraction of individual long swell waves at a water depth shallower than about 70 m, caused by the influence of underwater topography in coastal areas, is imaged on the radar scenes. A technique is developed for tracking wave rays depending on changes in swell wavelength and direction. We estimate the wave energy flux along wave tracks from deep water to the coastline based on SAR information: wave height and wavelength are derived from TS-X data.     

基于温度调制的气体传感器动态信号识别研究

利用4只掺杂Pt的SnO2微热板气体传感器组成传感器阵列来识别三种不同的工业气体（ CO, CH4和C2 H5 OH）,传感器加热分别采用了三角波、正弦波、锯齿波和脉冲波四种温度调制模式。然后将得到的传感器动态响应信号进行短时傅里叶变换（ STFT）提取特征信息,并结合主成分分析（ PCA）方法将特征信息进行降维处理,发现调制周期对气体种类影响较小。最后利用决策树识别三种不同的气体,识别准确率较高。实验结果证明了该算法的正确性和可行性。     

基于小波神经网络的结晶器漏钢预报技术研究

介绍了预报粘结性漏钢的基本方法,并对结晶器热电偶测得的大量温度数据进行预处理,再利用小波神经网络技术对经过预处理的检测数据进行训练,优化神经网络系统的结构和参数,识别出具有漏钢征兆的波形,提高了预报系统的精度和快速性;给出了用MATLAB实现的网络训练和测试的仿真结果,同时用VC开发了能识别结晶器内单偶、横向、纵向漏钢征兆温度波形的仿真系统。     

基于声波信号的水平井钻采控制技术

水平井是一种特殊的油井,特点是井眼轨迹多样、井内流体流动状态多变,采用常规钻采控制技术无法有效进行水平井钻采作业.基于声波信号的控制技术对水平井井下环境和介质没有特殊要求,能够实现地面与井下之间的无线信号传输及控制,建立起人井对话平台,长期实时监测水平井钻采动态数据,及时调整钻井的分段和换层,实现了水平井钻采控制自动化和智能化.     

基于小波分解的多尺度PCA周期性攻击检测算法

在工业控制网络中任何异常入侵行为都直接影响现场控制与决策,工控系统的安全检测迫在眉睫;工业控制系统中存在正弦波攻击,三角波攻击和方波攻击等周期性入侵攻击,这些攻击隐蔽的分布很难被检测出来并且会造成机器的磨损,目前针对该类攻击检测研究较少;针对以上问题,首先采用小波分解把数据分解到各个尺度上,然后采用主成分分析进行局部检测,最后把各个尺度的主成分分析组成一个包含各尺度信息的综合主成分分析模型;通过在公开数据集及自建数据集的周期性攻击实验结果表明,采用该算法比采用单独主成分分析算法进行攻击检测的整体准确率提高7.4％.     

Control of an Inverted Pendulum on a Wheel

Automation and Remote Control - We consider a mechanical system consisting of a wheel and a pendulum suspended on the wheel axis. The wheel rolls on a horizontal surface. The problem of...     

Three‐dimensional split‐step‐fourier and finite difference time domain‐based rectangular waveguide filter simulators: Validation,verification, and calibration

The split‐step‐Fourier‐based three‐dimensional wave propagation prediction and finite‐difference time‐domain‐based simulators are developed to show network scattering parameters of rectangular waveguide filters with horizontal and/or vertical windows as capacitive and/or inductive irises, respectively. The three‐dimensional‐split‐step parabolic equation simulator is applied to rectangular waveguide filters, and the results are compared with finite‐difference time‐domain model through tests inside a rectangular waveguide. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:660–667, 2016.