The relation of steady evaporating drops fed by an influx and freely evaporating drops

We discuss a thin film evolution equation for a wetting evaporating liquid on a smooth solid substrate. The model is valid for slowly evaporating small sessile droplets when thermal effects are insignificant, while wettability and capillarity play a major role. The model is first employed to study steady evaporating drops that are fed locally through the substrate. An asymptotic analysis focuses on the precursor film and the transition region towards the bulk drop and a numerical continuation of steady drops determines their fully non-linear profiles. Following this, we study the time evolution of freely evaporating drops without influx for several initial drop shapes. As a result we find that drops initially spread if their initial contact angle is larger than the apparent contact angle of large steady evaporating drops with influx. Otherwise they recede right from the beginning.     

Experimental and numerical modeling of particle levitation and movement behavior on traveling-wave electric curtain for particle removal

Traveling-wave electric curtain (EC) has been developed for potential application in particle removal/shield on solar panels and other surfaces. Levitation and transport of a particle in a traveling-wave electric field were simulated. Results show that levitation directions/angles and levitation trajectories differ because of the difference in starting positions and starting times. The particles in the two positive acceleration regions are levitated in opposite directions, and the particles distributed on the dielectric surface are levitated and transported successively rather than simultaneously. Movement trajectories are complex and affected by various factors. In the current paper, movement trajectories are modeled to analyze which motion modes are advantageous or disadvantageous to particle removal. This process is beneficial to elucidate the mechanism of particle removal and provide a guidance for movement control by designing appropriate operating parameters.     

Ballistics Model for Particles on a Horizontal Plane in a Vacuum Propelled by a Vertically Impinging Gas Jet

In previous work, a time-stepped numerical algorithm to compute particle trajectories consisting of lunar soil blown by the engine exhaust of a lunar lander was developed. The time-stepped integration method relies on the gas density, velocity, and temperature fields, calculated by computational fluid dynamics simulations, to compute the forces and accelerations acting on single noninteracting particles. In this paper, a computationally efficient particle ballistics model is presented where the trajectory is estimated by computing the vertical position (axial coordinate x) as a function of the horizontal position (radial coordinate y) using a constant horizontal velocity and a vertical acceleration approximated as a power-law. The unknown parameters of the model are determined by fitting the ballistics trajectory path to a matrix of trajectories generated by the time-step integration method using the rocket exhaust gas properties predicted by computational fluid dynamics software. Also in previous work, a strictly empirical trajectory model was developed to satisfy the need for a computationally efficient method of computing particle trajectories. This new model (like the previous model) is expressed as a time-independent trajectory path function. However, the method of this current work is based on physical laws of motion, unlike the previous empirical model.     

基于粒子群算法的6自由度机械臂动力学模型参数辨识

提出了基于粒子群优化(PSO)算法的工业机器人动力学参数辨识方法。首先利用改进的牛顿-欧拉方法,建立考虑关节摩擦的机械臂线性动力学模型,然后引入PSO算法,建立基于PSO算法的估计未知动力学参数的算法,最后以UR工业机器人为实验对象,通过设计激励轨迹,激励工业机器人关节运动,并对关节运动参数进行采样,实现UR工业机器人的动力学参数估计,并根据力矩预测精度验证动力学模型。实验证明了所提出算法辨识工业机器人动力学模型参数的准确性和有效性。     

Numerical model of particle deposition on fin surface of heat exchanger

Dust particle deposition on fin surface has a significant influence on the performance of fin-and-tube heat exchangers, and the purpose of this study is to develop a numerical model for predicting the particle deposition rate on fin surface. In the model, the particle trajectories were calculated by the particle motion equation; the particle deposition on the fin surface was described based on the critical impact angle and the critical sticking velocity of incident particles; the particle deposition on the formed fouling layer was described based on the critical impact angle, the critical sticking velocity and the critical removal velocity of incident particles. The particle distributions on fin surface predicted by the model agree well with the images captured in the visualization experiment. The predicted particle deposition weight per unit area can describe 88% of the experimental data within a deviation of ±20% and the mean deviation is 12.8%.     

Global parameterization of a topological surface defined as a collection of trimmed bi‐parametric patches: Application to automatic mesh construction

We describe a new geometric algorithm to map surfaces into a plane convex area. The mapping transformation is bijective; it redefines the whole surface as a unique bi‐parametric patch. Thus this mapping provides a global parametrization of the surface. The surfaces are issued from industrial CAD software; they are usually described by a large number of patches and there are many shortcomings. Indeed, the decomposition into patches depends on the algorithm of the geometric modelling system used for design and usually has no meaning for any technological application. Moreover, in many cases, the surface definition is not compatible, i.e. patches are not well connected, some patches are self‐intersecting or intersect each other. Many applications are hard to address because of these defects. In this paper we show how patch‐independent meshing techniques may be easily automated using a unique metric in a plane parametric space. Thus we provide an automatic procedure to build valid meshes over free‐form surfaces issued from industrial CAD software (Computer Aided Design: this terminology should refer to a large amount of software. For the scope of this paper we only refer to geometric modelling systems. Indeed geometric modelling systems remain the kernel of many CAD software). Copyright © 2002 John Wiley & Sons, Ltd.     

Software Assurance Using Structured Assurance Case Models

Software assurance is an important part of the software development process to reduce risks and ensure that the software is dependable and trustworthy. Software defects and weaknesses can often lead to software errors and failures and to exploitation by malicious users. Testing, certification and accreditation have been traditionally used in the software assurance process to attempt to improve software trustworthiness.In this paper, we examine a methodology known as a structured assurance model, which has been widely used for assuring system safety, for its potential application to software assurance. We describe the structured assurance model and examine its application and use for software assurance. We identify strengths and weaknesses of this approach and suggest areas for further investigation and testing.     

基于Matlab/Simulink的送标机构运动仿真分析

针对六连杆作为贴标机的送标机构,基于几何矢量相等建立了其数学模型,利用Matlab／Simulink对该模型进行计算和仿真。通过对比标盒所处不同位置的运动轨迹,获得了最优结果,并在此结果基础上探讨了吸标辊的安装尺寸。     

Bipolaron Jahn–Teller Pairing and Charge Transport in Cuprates

Recently the mechanism for an intersite pairing was proposed for cuprates, where the coupling of two fold electronic degenerated levels to local lattice models at finite wave vector was introduced. The model is able to describe the stripe phase and offers a possible explanation of the pseudogap. Moreover, we argue that the single particle and pair conductivity may differ. For a better analysis on this issue, we compute the charge mobility arising from single particle using a variable range hopping model. The general trend is that the mobility has a crossover from 1/T temperature behavior at high temperature to a strong reduction of the mobility at low temperatures.     

Ventricular segmentation and modeling using topological watershed transformation and harmonic state model

This paper proposes an adapted ventricular segmentation method based on topological watershed transform. Segmentation will allow spatio-temporal modeling of trajectories of the different points belonging to the borders of the ventricle using a harmonic motion model that is able to describe such motion over the entire cardiac cycle. In addition, extraction of the adopted canonical state vector and the corresponding state equations guarantees an optimal efficacy and a gradual transition from order n to order n + 1. To validate the proposed approach, an intern-image base was used. Our results show a promising ability to discern whether subjects are healthy or pathological with an 80% success rate.     

Three-dimensional simulation of a plasma jet with transverse particle and carrier gas injection

In the present paper, three-dimensional modeling results are presented concerning the turbulent thermal plasma jet with transversely injected carrier gas and metal particles at atmospheric pressure. The standard K− model is employed for the numerical simulation of the turbulent plasma flow in coupling with the variable-property continuity, momentum and energy equations. For predicting the motion of the injected particles in the turbulent flow field, an improved particle stochastic-trajectory model is adopted in the calculation. The heating histories of the injected particles are also calculated in their moving processes. The modeling results show that including the effect of carrier gas on jet and particle behavior is very important. The plasma jet is deflected from its geometrical axis due to the transverse injection of carrier gas, and the particle trajectories are also appreciably changed by the carrier gas injection. The particles disperse around their average trajectories in the turbulent flow field.     

Hyperbolic systems of conservation laws in gravity-driven,particle-laden thin-film flows

Our study focuses on gravity-driven, particle-laden flows that are pertinent to a wide range of industrial and geophysical settings in which transport of suspensions occurs. In the present study we employ a previously derived model by Murisic et al. (Physica D, 240, 2011) that uses the lubrication approximation to describe particle-laden films on an incline. The model consists of a coupled system of hyperbolic conservation laws for the interface position and the particle concentration. While it has been shown that the model compares well quantitatively with experiments, it lacks analysis. The objectives of this paper focus on the study of the Riemann problem for this system of conservation laws and how the results relate to experiments. We investigate the governing system analytically and numerically; the equations exhibit rich mathematical structures, including double-shock wave solutions, rarefaction waves, and singular shocks.     

Using data compression in automatic test equipment for system-on-chip testing

Compression has been used in automatic test equipment (ATE) to reduce storage and application time for high volume data by exploiting the repetitive nature of test vectors. The application of a binary compression method to an ATE environment for manufacturing is studied using a technique, referred to as reuse. In reuse, compression is achieved by partitioning the vector set and removing repeating segments. This process has O(n/sup 2/) time complexity for compression (where n is the number of vectors) with a simple hardware decoding circuitry. It is shown that for industrial system-on-chip (SoC) designs, the efficiency of the reuse compression technique is comparable to sophisticated software techniques with the advantage of easy and fast decoding. Two shift register-based decompression schemes are presented; they can be either incorporated into internal scan chains or built in the tester's head. The proposed compression method has been applied to industrial test and data and an average compression rate of 84% has been achieved.     

Coupling resolved and coarse-grain DEM models

The discrete element method (DEM) is a well-established approach to study granular flows in numerous fields of application; however, the DEM is a computationally demanding method. Thus, simulations of industrial scale systems are hardly feasible on today’s hardware. This situation is typically resolved by limiting the simulation domain or introducing a coarse-grain model. While the former approach does not provide information of the full system, the latter is especially problematic in systems, where geometric restrictions are in the range of particle size, so both are insufficient to adequately describe large-scale processes. To overcome this problem, we propose a novel technique that efficiently combines resolved and coarse-grain DEM models. The method is designed to capture the details of the granular system in spatially confined regions of interest while retaining the benefits of the coarse-grain model where a lower resolution is sufficient. To this end, our method establishes two-way coupling between resolved and coarse-grain parts by volumetric passing of boundary conditions.     

Amplitude and phase microscopy for sizing of spherical particles

We describe a numerical vector diffraction model based on Mie theory that describes the imaging of spherical particles by bright-field, confocal, and interferometric microscopes. The model correctly scales the amplitude-scattered field relative to the incident field so that the forward-scattered and incident light can be interfered to correctly model imaging with copolarization transmission microscopes for the first time to our knowledge. The model is used to demonstrate that amplitude and phase imaging with an interferometric microscope allows subwavelength particle sizing. Furthermore, we show that the phase channel allows much smaller particles to be sized than amplitude-only measurements. The model is validated by experimental measurements.     

A model for the induction of chromosome aberrations through direct and bystander mechanisms

A state vector model (SVM) for chromosome aberrations and neoplastic transformation has been adapted to describe detrimental bystander effects. The model describes initiation (formation of translocations) and promotion (clonal expansion and loss of contact inhibition of initiated cells). Additional terms either in the initiation model or in the rate of clonal expansion of initiated cells, describe detrimental bystander effects for chromosome aberrations as reported in the scientific literature. In the present study, the SVM with bystander effects is tested on a suitable dataset. In addition to the simulation of non-linear effects, a classical dataset for neoplastic transformation in C3H 10T1/2 cells after alpha particle irradiation is used to show that the model without bystander features can also describe LNT-like dose responses. A published model for bystander induced neoplastic transformation was adapted for chromosome aberration induction and used to compare the results obtained with the different models.     

Scalar field,gauge invariance and orbital angular momentum of light

Motivated by the nice form of the Poynting vector for the paraxial light a gauge theoretic formalism is proposed representing light by a complex massless scalar field. Angular momenta for paraxial beam and multipole radiation are derived using this approach. It is pointed out that a natural covariant generalization for the rotating system would offer an alternative formalism to rotating light beams.     

A new approach to track finding and fitting in vector drift chambers

We describe the algorithm that is used to find and fit charged particle trajectories in the Mark III detector at SPEAR. The computer program uses a novel non-numerical pattern recognition technique analogous to that used by the digital hardware in the experiment's track finding trigger processor. The technique is both fast and efficient. The complete reconstruction of events is performed at a rate of 37 ms per track on an IBM 3081K, compared with 91 ms per track with a more conventional technique. A preliminary fit of all tracks, suitable for online monitoring, is available after 15 ms per track. Similar techniques are also applicable to future experiments operating in high multiplicity environments. The organization of the algorithms is such as to lead to simple implementation on vector processors.     

ISOTHERMAL PREDICTION OF PARTICLE AND GAS FLOW IN A COAL-FIRED REACTOR

The steady, turbulent gas flow with entrained coal particles in a laboratory-scale axisymmetric coal gasification reactor is numerically analyzed. The reactor is designed to provide rapid mixing and heatup of the coal in a configuration which results in a nearly isothermal and uniform flow in the main reaction chamber so as to allow controlled study of coal gasification. A detailed knowledge of the reactor dynamics is required in order to interpret experimental results. The nonreacting, isothermal flow pattern is first presented as a base case. Calculations are performed with an iterative, implicit scheme suitable to the elliptic nature of the gas flow equations in an Eulerian frame-work. The turbulent motion is resolved using the eddy-viscosity concept with the standard k-ε turbulence model. Coal particle trajectories are then calculated using the Lagrangian form of the momentum equations. The influence of solid particles on the gas phase is neglected. Particle trajectories and residence time distributions are presented for a variety of particle sizes and particle inlet locations. The influence of the inlet conditions, turbulent diffusion, and gravity on the particle motion, are investigated. Implications of the predictions, with respect to the design of the reactor, are discussed.