Boussinesq systems in two space dimensions over a variable bottom for the generation and propagation of tsunami waves

Considered here are Boussinesq systems of equations of surface water wave theory over a variable bottom. A simplified such Boussinesq system is derived and solved numerically by the standard Galerkin-finite element method. We study by numerical means the generation of tsunami waves due to bottom deformation and we compare the results with analytical solutions of the linearized Euler equations. Moreover, we study tsunami wave propagation in the case of the Java 2006 event, comparing the results of the Boussinesq model with those produced by the finite-difference code MOST, that solves the shallow water wave equations.     

Travelling waves in a reaction-diffusion model for electrodeposition

In this paper we consider an analytical and numerical study of a reaction-diffusion system for describing the formation of transition front waves in some electrodeposition (ECD) experiments. Towards this aim, a model accounting for the coupling between morphology and composition of one chemical species adsorbed at the surface of the growing cathode is addressed. Through a phase-space analysis we prove the existence of travelling waves, moving with specific wave speed. The numerical approximation of the PDE system is performed by the Method of Lines (MOL) based on high order space semi-discretization by means of the Extended Central Difference Formulae (D2ECDF) introduced in [1]. First of all, to show the advantage of the proposed schemes, we solve the well-known Fisher scalar equation, focusing on the accurate approximation of the wave profile and of its speed. Hence, we provide numerical simulations for the electrochemical reaction-diffusion system and we show that the results obtained are qualitatively in good agreement with experiments for the electrodeposition of Au-Cu alloys.     

A network flow model for clustering segments and minimizing total maintenance and rehabilitation cost

Because of shrinking budgets, transportation agencies are facing severe challenges in the preservation of deteriorating pavements. There is an urgent need to develop a methodology that minimizes maintenance and rehabilitation (M&R) cost. To minimize total network M&R cost of clustering pavement segments, we propose an integer programming model similar to an uncapacitated facility location problem (UFLP) that clusters pavement segments contiguously. Based on the properties of contiguous clustered pavement segments, we have transformed the clustering problem into an equivalent network flow problem in which each possible clustering corresponds to a path in the proposed acyclic network model. Our proposed shortest-path algorithm gives an optimal clustering of segments that can be calculated in a time polynomial to the number of segments. Computational experiments indicate our proposed network model and algorithm can efficiently deal with real-world spatial clustering problems.     

A feature model of surface pressure and wind fields associated with the passage of atmospheric cold fronts

A computer program for the analytical simulation of surface pressure and wind fields associated with a cold front passage is presented. Surface pressure and wind fields are obtained overlapping three elemental fields. The main characteristics are obtained using a basic field that builds the warm and cold sectors of the system, each one with straight and parallel isobars, that twist at the frontal line. Cyclonic rotation around the low pressure center is given by including a solid rotation field. The wind field is computed as a proportion of the associated geostrophic wind. The cross-isobar effect of the surface wind, from high to low pressures, is obtained by using a convergent or sink field. Surface fields and the front move eastward with constant speed and the front can also rotate cyclonically around the low center. The way the subroutines can be implemented in pressure- and wind-forced ocean models is presented. Some examples for Northern and Southern Hemispheres are described.     

三分子自催化反应扩散系统中化学波的二维格子Boltzmann模拟

建立二维区域带平方衰减反应的三分子自催化反应扩散系统的数学模型,利用浓度分布的Chapmann-Enskogz展开及多尺度技术,给出基于格子Boltzmann模型的二维三分子自催化反应扩散系统的数值求解法,得到半开放自催化反应扩散系统在反应与扩散机制同时作用所产生化学波的过程和浓度空间分布值.数值结果表明本文提供的求解化学波现象的方法是有效的.     

Mathematical model for in-line determination of heat transfer coefficients in a steam generation process

This paper shows an in-line determination of heat transfer coefficients in a steam generator. Aqueous working solution of lithium bromide ＋ ethylene glycol was considered. Heat transfer coefficients were calculated for the working solution and for heating water. A plate heat exchanger was used as the steam generator. Type T thermocouples were used to measure the wall temperature in the plate heat exchanger, which is a main component in an absorption system. Absorption systems are equipments able to use alternative energy, diminishing polluting emissions. Commercial software Agilent Vee Pro 7.5 by Agilent Technologies was used to measure the temperatures and for the determination of the heat transfer coefficients. Whir the in - line determination of the heat transfer coefficients it will be possible to know the best operation conditions during the experimental test. There are not previous works in a steam generator with this working solution.     

A hybrid artificial intelligence model for river flow forecasting

A hybrid hydrologic estimation model is presented with the aim of performing accurate river flow forecasts without the need of using prior knowledge from the experts in the field. The problem of predicting stream flows is a non-trivial task because the various physical mechanisms governing the river flow dynamics act on a wide range of temporal and spatial scales and almost all the mechanisms involved in the river flow process present some degree of nonlinearity. The proposed system incorporates both statistical and artificial intelligence techniques used at different stages of the reasoning cycle in order to calculate the mean daily water volume forecast of the Salvajina reservoir inflow located at the Department of Cauca, Colombia. The accuracy of the proposed model is compared against other well-known artificial intelligence techniques and several statistical tools previously applied in time series forecasting. The results obtained from the experiments carried out using real data from years 1950 to 2006 demonstrate the superiority of the hybrid system.     

气体流速流向传感器及其温度补偿的研究

设计了一种内燃机用气体流速、流向传感器,阐述了传感器的工作原理;介绍了应用单片机对传感器输出信号进行线性化和温度补偿处理的方法。试验结果表明:该传感器在-20~100℃温度范围内,温度稳定性高,零点温度漂移为4.0×10-3%FS/℃,准确度可达到±1.0%FS,性能指标达到了设计要求。     

A new algorithm for the extraction of the surface waves for the Green''''s function in layered dielectrics

There exist the complicated waveguide modes as well as the surface waves in the electromagnetic field induced by a horizontal electric dipole in layered lossless dielectrics between two ground planes. In spectral domain, all these modes can be characterized by the rational parts with the real poles of the vector and scalar potentials. The accurate extraction of these modes plays an important role in the evaluation of the Green's function in spatial domain. In this paper, a new algorithm based on rational approximation is presented, which can accurately extract all the real poles and the residues of each pole simultaneously. Thus, we can get all the surface wave modes and waveguide modes, which is of great help to the calculation of the spatial domain Green's function. The numerical results demonstrated the accuracy and efficiency of the proposed method.     

Manifold method coupled velocity and pressure for Navier-Stokes equations and direct numerical solution of unsteady incompressible viscous flow

Numerical manifold method (NMM) application to direct numerical solution for unsteady incompressible viscous flow Navier-Stokes (N-S) equations was discussed in this paper, and numerical manifold schemes for N-S equations were derived based on Galerkin weighted residuals method as well. Mixed covers with linear polynomial function for velocity and constant function for pressure was employed in finite element cover system. The patch test demonstrated that mixed covers manifold elements meet the stability conditions and can be applied to solve N-S equations coupled velocity and pressure variables directly. The numerical schemes with mixed covers have also been proved to be unconditionally stable. As applications, mixed cover 4-node rectangular manifold element has been used to simulate the unsteady incompressible viscous flow in typical driven cavity and flow around a square cylinder in a horizontal channel. High accurate results obtained from much less calculational variables and very large time steps are in very good agreement with the compact finite difference solutions from very fine element meshes and very less time steps in references. Numerical tests illustrate that NMM is an effective and high order accurate numerical method for unsteady incompressible viscous flow N-S equations.     

无人机测控与信息传输信道的建模与仿真设计

分析了无人机测控与信息传输系统中传输信道的特点,针对无人机飞行中不同的状态和环境条件,建立了不同的信道模型,并在此基础上,设计了一个可用于无人机测控与信息传输系统设计的信道仿真器,该仿真器通过设置不同的参数,可对无人机飞行中所处的不同通信信道进行仿真,以全面验证无人机测控与信息传输系统中所采用的传输技术性能及接收机性能.     

Using electric actuation and detection of oscillations in microcantilevers for pressure measurements

Response characteristics of a microcantilever, such as resonant frequency, amplitude, phase and quality factor, can be used for absolute pressure measurements in the range of 10⁻⁴ to 10³ Torr. To this end, it would be very convenient to have the resonance of the microcantilever actuated and detected electrostatically. Herein, we report the nonlinear dynamics of microcantilevers under varying pressure and different gases using the harmonic detection of resonance (HDR) technique [J. Gaillard, M.J. Skove, R. Ciocan, A.M. Rao, Electrical detection of oscillations in 340 microcantilevers and nanocantilevers, Rev. Sci. Instrum. 77 (2006) 073907]. The HDR technique exploits nonlinearities in the cantilever-counter electrode system to allow electrostatic actuation and detection of the responses of the microcantilever to the pressure and gas composition. In particular, the 2nd and 3rd harmonics of the measured charge on the cantilever are investigated. The microcantilever demonstrates a quality factor of 10,000 at 10⁻³ Torr, and a usable response in the range from 10⁻³ to 10³ Torr. The use of different harmonics can enable us to adjust the range of pressures over which the sensor has an efficacious response, enhancing its sensitivity to a particular environment. The experimental results are in reasonable agreement with theoretical calculations, despite the nonlinearities involved.     

A well deliverability model for non-Darcian flow in geothermal reservoirs

A new numerical algorithm is proposed to estimate the deliverability of a geothermal well. The mathematical model assumes a single-component fluid. The model accounts for both the phase change phenomenon and the non-Darcian behavior of the flow. The contemporaneous presence of both effects has to the authors’ knowledge never been fully taken into account. Provided that the numerical solution is based on a finite differences or finite volumes method, the numerical code we developed (called DNDmultiphase) can be plugged as an additional module into existing codes devoted to simulations of a whole reservoir (such as TOUGH2 or HYDROTHERM).     

Objective firmness, average pressure and subjective perception in mattresses for the elderly

For elderly people, the desirable situation of living independently means facing everyday tasks and risks alone [Monk et al., 2006. Towards a practical framework for managing the risks of selecting technology to support independent living. Appl. Ergon. 37, 599-606]. One such task is buying a mattress through the same channels as younger people. Quite short trials (if any) in the store are usually the only basis for choice. Despite the long-term effects a mattress may have on the user, acceptance or rejection largely depends on this extremely short trial experience. This paper aims to cover the salient mechanical aspects of comfort and usability (rolling, getting up). The results should help manufacturers to know if the long-term benefits of their products are perceived in the short term by senior citizen customers. Four mattresses for the elderly chosen from a sample of 17 available on the Spanish market were compared in pairs for short-term effects (1 min pressure with both hands, 1 min sitting, 1 min lying on back, and 1 min lying on side), simulating a store purchasing trial by a group of young and elderly people in terms of differences between perceived firmness, usability (ease of movement) and comfort. The results of these comparisons were correlated to differences in objective properties such as pressure distribution and objective firmness. No differences in perception were found between young and old users. Only two of the four test methods for perceiving mattress firmness were necessary to explain the majority of variance: pressing the surface of the mattress with a part of the body (both hands or buttocks), and contact using the entire body (lying on back or side). A number of significant relationships were found, with the following of note: increments in 'objective firmness' (estimated from test load/deflection) correlate positively to increments in 'perceived firmness'; increments in 'average pressure' (measured using a mannequin) correlate positively to increments (within certain limits) in 'perceived firmness'; increments in 'objective firmness' and in 'average pressure' are associated with increments in 'overall comfort' and with reductions in 'difficulty in rolling". Finally, it was found that people with a higher body mass index tend to be (weak correlation) more sensitive to changes in 'objective firmness'.     

一种基于SystemC的系统级软硬件协同设计新模型

分析了SystemC的建模特性,提出了一种基于SystemC的系统级设计新模型,即从系统功能描述开始逐步细化,建立模型间通信抽象的事务模型,对抽象通信具体化,最后形成通信模型。以此为基础进行RTL级综合,完成软硬件协同设计。本方法应用于一款导航芯片的设计,有效地缩短了研制周期,降低了开发成本,提高了系统设计质量。     

Blood flow dynamics and arterial wall interaction in a saccular aneurysm model of the basilar artery

Blood flow dynamics under physiologically realistic pulsatile conditions plays an important role in the growth, rupture and surgical treatment of intracranial aneurysms. This paper describes the flow dynamics and arterial wall interaction in a representative model of a terminal aneurysm of the basilar artery, and compares its wall shear stress, pressure, effective stress and wall deformation with those of a healthy basilar artery. The arterial wall was assumed to be elastic or hyperelastic, isotropic, incompressible and homogeneous. The flow was assumed to be laminar, Newtonian, and incompressible. The fully coupled fluid and structure models were solved with the finite elements package ADINA. The intra-aneurysmal pulsatile flow shows single recirculation region during both systole and diastole. The pressure and shear stress on the aneurysm wall exhibit large temporal and spatial variations. The wall thickness, the Young’s modulus in the elastic wall model and the hyperelastic Mooney-Rivlin wall model affect the aneurysm deformation and effective stress in the wall especially at systole.     

A finite element approach for analyzing the effect of cushion type and thickness on pressure ulcer

Immobilization or continuous sitting with a constant posture for a long time in office environment causes sub-dermal tissue damage. Tissue damage occurs because of continuous prolonged compression of buttock soft tissue under body weight. It is treated as the end result of cell death or tissue deformation which ultimately gives rise to pressure ulcer. Although the sub-dermal tissue refers to the tissue beneath the skin, it is the tissue just below the bony portion undergoes maximum deformation because the muscle endures a continuous high stress. In this work, a simple but practical numerical approach has been proposed to estimate the maximum stress beneath the bony structure (ischial tuberosity). The model is validated with experimental data from the literature. Effect of properties of cushion material, loading angle and thickness of cushion has been analyzed. The cushion properties and thickness that can reduce maximum stress at ischial tuberosity have been demonstrated. The effect of sitting posture on maximum stress at ischial tuberosity has also been shown.     

A call-independent and automatic acoustic system for the individual recognition of animals: A novel model using four passerines

Research into acoustic recognition systems for animals has focused on call-dependent and species identification rather than call-independent and individual identification. Here we present a system for automatic call-independent individual recognition using mel-frequency cepstral coefficients and Gaussian mixture models across four passerine species. To our knowledge this is the first application of these techniques to the individual recognition of birds, and the results are promising. Accuracies of 89.1-92.5% were achieved and the acoustic feature and classifier method developed here have excellent potential for individual animal recognition and can be easily applied to other species.     

An intelligence-based route choice model for pedestrian flow in a transportation station

This study proposes a method that uses an artificial neural network (ANN) to mimic human decision-making about route choice in a crowded transportation station. Although ANN models have been developed rapidly and widely adopted in various fields in the last three decades, their application to predict human decision-making in pedestrian flows is limited, because the video clip technology used to collect pedestrian movement data in crowded conditions is still primitive. Data collection must be carried out manually or semi-manually, which requires extensive resources and is time consuming. This study adopts a semi-manual approach to extract data from video clips to capture the route choice behaviour of travellers, and then applies an ANN to mimic such decision-making. A prediction accuracy of 86% (ANN model with ensemble approach) is achieved, which demonstrates the feasibility of applying the ANN approach to decision-making in pedestrian flows.     

A model for integrating process planning and production planning and control in machining processes

The goal of process planning is to propose the routing of a previously designed part and results in a sequence of operations and their parameters. It concerns and requires detailed information about the process. The goal of production planning, on the other hand, is to schedule, sequence and launch the orders introduced on the routing sheet into the job-shop according to the enterprise's strategic goal and the actual conditions of the production plant. The goals, information and decisions taken in process planning and production planning and control are often very different and, because of that, it is very difficult to integrate them.

The objective of this work is to develop a model that can be applied in the future to the development of an integrated process planning and scheduling tool using an integrated definition (IDEF) methodology to design an activity model, which integrates process and production planning in metal removal processes. An activity model will be used to develop a system that allows the user to plan the process and the production at the same time in collaborative engineering work. To design the activity model, a wide range of parts were evaluated and processed in an actual job-shop factory. Several activities were developed in detail to be tested in real cases, and an example of one of them is introduced in this article.