LOCAL DISCONTINUOUS GALERKIN METHOD FOR ELLIPTIC INTERFACE PROBLEMS

In this paper,the minimal dissipation local discontinuous Galerkin method is studied to solve the elliptic interface problems in two-dimensional domains.The interface may be arbitrary smooth curves.It is shown that the error estimates in L;-norm for the solution and the flux are O（h;|log h|）and O(h|log h|;),respectively.In numerical experiments,the successive substitution iterative methods are used to solve the LDG schemes.Numerical results verify the efficiency and accuracy of the method.

Mathematical treatment of wave propagation in acoustic waveguides with n curved interfaces

There are some curved interfaces in ocean acoustic waveguides. To compute wave propagation along the range with some marching methods, a flattening of the internal interfaces and a transforming equation are needed. In this paper a local or-thogonal coordinate transform and an equation transformation are constructed to flatten interfaces and change the Helmholtz equation as a solvable form. For a waveguide with a flat top, a flat bottom and n curved interfaces, the coefficients of the trans-formed Helmholtz equation are given in a closed formulation which can be thought of as an extension of the formal work related to the equation transformation with two curved internal interfaces. In the transformed horizontally stratified waveguide, the one-way reformulation based on the Dirichlet-to-Neumann (DtN) map is then used to reduce the boundary value problem to an initial value problem. Numerical implementation of the resulting operator Riccati equation uses a large range step method to discretize the range variable and a truncated local eigenfunction expansion to approximate the operators. This method is particularly useful for solving long range wave propagation problems in slowly varying waveguides. Furthermore, the method can also be applied to wave propagation problems in acoustic waveguides associated with varied density.

Thermal transport in composition graded silicene/germanene heterostructures

Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,we investigated the influence of composition gradient length and heterogeneous particles at the silicene/germanene(SIL/GER)heterostructure interface on heat conduction.Our results indicate that composition graded interface at the interface diminishes the thermal conductivity of the heterostructure,with a further reduction observed as the length increases,while the effect of the heterogeneous particles can be considered negligible.To unveil the influence of composition graded interface on thermal transport,we conducted phonon analysis and identified the presence of phonon localization within the interface composition graded region.Through these analyses,we have determined that the decrease in thermal conductivity is correlated with phonon localization within the heterostructure,where a stronger degree of phonon localization signifies poorer thermal conductivity in the material.Our research findings not only contribute to understanding the impact of interface gradient-induced phonon localization on thermal transport but also offer insights into the modulation of thermal conductivity in heterostructures.

数字界面本土化:超越语言的跨文化设计

随着信息全球化的发展,数字界面需要面向全球不同文化开展有效的本土化设计,以适应多元文化群体的需求。从跨文化视角出发,数字界面本土化设计中存在标准化可能忽视文化变异的价值,生产效率可能会弱化设计创新,以及表面的中立选择可能隐含文化偏见等诸多困境。为分析这一系列问题,本文从麦克卢汉的媒介环境理论出发,关注不同媒介环境对多元文化的适应性,强调文化差异的动态适应机制。通过描绘数字界面本土化设计中的文化困境,提出数字界面设计的伦理反思,激发对其中潜在文化政治因素的思辨,进而拓展和丰富麦克卢汉理论在数字语境中的应用价值。

嵌入式技术下无线传感通信网络拥塞控制系统

无线传感通信网络在数据传输过程中容易出现网络拥塞,存在全局吞吐量小、端到端延时大、节点丢包率高的问题,导致网络拥塞控制效果不佳。为了解决这个问题,设计一种嵌入式技术下无线传感通信网络拥塞控制系统。设计嵌入式以太网拥塞数据交换接口电路,采用嵌入缓冲器开环控制模块结构,根据排队长度变化控制数据包丢弃率。计算接收方通告窗口大小,检测高、低优先级传输网络拥塞情况。通过计算拥塞节点发送速率来控制高、低优先级传输网络局部拥塞。将全局拥塞竞争窗口变为当前窗口,使用检测缓存队列占空率方式控制全局拥塞。测试结果表明,所设计系统最大吞吐量为2600 b/s,最大端到端延时为18 s,最大节点丢包率为2.0%,使用该系统能够提升网络拥塞控制效果。

民宿建筑的在地语义表达——柳湖阳山居民宿设计

依据在地性建筑设计理论,以柳湖阳山居民宿为例证,旨在通过对本土建筑的语义提取来营造出融入当地自然与人文环境的民宿建筑。以在地性建筑设计方法为指导,选取柳湖阳山居各不同功能的建筑体作为设计对象,利用对本土建筑的原型解读与设计场地景观关系处理,确定从平面布局、外观造型、景观朝向进行民宿设计。实例论证发现,在地语义表达是本土建筑形式对场地环境的继承与回应。柳湖阳山居民宿体现的在地性设计理念,有助于民宿专属建筑设计语言的出现。

Novel Biological Based Method for Robot Navigation and Localization

The capability and reliability are crucial characteristics of mobile robots while navigating in complex environments. These robots are expected to perform many useful tasks which can improve the quality of life greatly. Robot localization and decisionmaking are the most important cognitive processes during navigation. However, most of these algorithms are not efficient and are challenging tasks while robots navigate through complex environments. In this paper,we propose a biologically inspired method for robot decision-making, based on rat’s brain signals. Rodents accurately and rapidly navigate in complex spaces by localizing themselves in reference to the surrounding environmental landmarks. Firstly, we analyzed the rats’ strategies while navigating in the complex Y-maze, and recorded local field potentials(LFPs), simultaneously.The recorded LFPs were processed and different features were extracted which were used as the input in the artificial neural network(ANN) to predict the rat’s decision-making in each junction. The ANN performance was tested in a real robot and good performance is achieved. The implementation of our method on a real robot, demonstrates its abilities to imitate the rat’s decision-making and integrate the internal states with external sensors, in order to perform reliable navigation in complex maze.

In-Solid Acoustic Source Localization Using Likelihood Mapping Algorithm

The significant challenge in human computer interaction is to create tangible interfaces that will make digital world accessible through augmented physical surfaces like walls and windows. In this paper, various acoustic source localization methods are proposed which have the potential to covert a physical object into a tracking sensitive interface. The Spatial Likelihood method has been used to locate acoustic source in real time by summing the spatial likelihood from all sensors. The source location is obtained from searching the maximum in the likelihood map. The data collected from the sensors is pre-processed and filtered for improvement of the accuracy of source localization. Finally a sensor fusion algorithm based on least squared error is presented to minimize the error while positioning the source. Promising results have been achieved experimentally for the application of acoustic tangible interfaces.

Meso-mechanical Interfacial Behavior of Elbow Steel Fiber Reinforced Concrete

The strain distributions near the interface when the elbow steel fiber is pulled out from the half-mould concrete matrix are directly measured using a combined method of single fiber pull-out test and digital image correlation. Meanwhile, the real-time processes of the bonding, debonding and sliding at the interface are observed. The micro-mechanism of the strain localization in the failure process of interface when debonding occurs and the strengthening mechanism at the imbedded fiber are discussed. The experimental results show that the meso-scale strain localization gives rise to the localization of shear damage near the fiber interface. This strain localization characterized by the debonding process near the interface occurs, develops and moves gradually at an apparently regular interval. At the elbow part of the imbedded fiber, the peak value of the shearing stress occurs. But the primary debonding does not occur at this place because the strength of the shear damage is increased at the local area of the elbow part in the concrete, displaying an apparent reinforced effect at the end of the fiber.

基于龙芯Local IO接口的UART IP核设计

针对龙芯系列CPU自带UART(Universal Asynchronous Receiver Transmitter)接口有限且Xilinx UART IP核与龙芯Local IO接口的不兼容问题,本文设计了一种适配龙芯CPU Local IO接口的UART IP核。该IP核能够直接挂载到Local IO接口上,实现龙芯CPU UART接口的扩展;利用发送FIFO与接收FIFO,实现串口数据的自动收发;通过设计接收阈值机制与接收超时机制,降低了中断触发的频率,杜绝了CPU频繁进入中断的情况。最后,在FPGA上进行设计实现,经过实际测试,该IP核实现了需求的功能,且性能稳定。

An Intelligent Robot based on Sound Source Localization and Ultrasound Distance Detection

In both industrial and research areas of electronic engineering,Sound Source Localization for robot control has always been an interesting subject to be further studied.Under some dangerous situation,especially when a special driver is required to implement a particular task,the device should be able to combine robotics control technology with Sound Source Localization,and take actions according to the different response patterns.In this research project,a multifunc-tional model driver,named "Mobile Island",has been designed and built up by integrating the Emulator 8051 micro-controller,Intel 8255 interfaces,some components and other necessary devices.The intelligent Mobile Island imple-mented by C language programs can operate under three control modes.In the sound control Mode 1,the model driver can detect and track a target by Sound Source Localization and then turn and move toward the destination.In the keypad control Mode 2,it can be controlled by a manual keypad.In the free run Mode 3,Mobile Island can move and turn by itself.When finding an object in front,it will turn away before moving forward again,so that it can avoid crashing on the obstacle.

基于国产MCU的直流塑壳断路器控制系统设计

在国产化替代的大趋势下,该方案设计了一种基于国产32位微处理器HC32F460的直流塑壳断路器控制器。该方案所设计的通信接口可以兼容不同的通信总线,提高了接口通用性。在原有的三段保护特性之上,提出了逆电流保护的概念和相应算法。支持人机(按键、显示屏)灵活调节参数和档位,适用范围更广,弥补了传统热磁式断路器动作误差大,参数不可调节的缺点。同时也可以通过通信总线实现遥控、遥信、遥调、遥测“四遥”功能,实现远程控制。该设计在实现预期功能的同时,大幅度降低了成本,对未来分布式能源和直流配电网的发展具有重要意义。

电力局域网通信安全态势智能感知系统设计

为了加强电力局域网对通信数据的承载能力,使整个通信网络呈现出相对稳定的连接形式,设计电力局域网通信安全态势智能感知系统。根据B/S框架体系,划分电力局域网内的元件分层形式,利用关联外部接口,实现模块与模块之间的连接。在此基础上,建立服务端通信线程,通过转发通信指令的方式,得到准确的数据信息解析结果,完成电力局域网的通信需求分析,结合相关硬件结构布局形式,实现电力局域网通信安全态势智能感知系统的应用。实验分析结果显示,与总线控制型系统相比,智能感知系统作用下电力局域网主机在单位时间内所能承载的通信数据量更大,对维持通信网络的稳定连接起到一定的促进作用。

Interface delamination of the thermal barrier coating subjected to local heating

To investigate the possible failure modes of the thermal barrier coating (TBC) used to protect the scramjet combustion chamber, the local heating via laser beam irradiation was utilized to simulate the service condition of high thermal flux and high temperature gradient. Firstly, the experimental method and process were described and the typical fracture morphology of the TBC under test were provided. Then, the theoretical and finite element modeling were carried out to study the temperature, deformation and stresses of the specimen when the top ceramic coat was subjected to local heating, and to demonstrate the mechanism on the failure of the TBC. It is revealed that the interface delamination shall appear and ultimately lead to the failure of the TBC under such thermal loading of local quick heating. According to the outcome of this study, the driving force of the interface delamination is influenced greatly by the key structural parameters and performance matching. Moreover, by utilizing the rules of the effects of these parameters on the fracture driving force, there is some possibility for the designer to optimize the performances of the TBC.

黏接界面脱黏损伤的缺陷局部内共振识别方法

黏接结构的界面脱黏将导致结构完整性的破坏,对界面黏接状态进行有效的检测和评估具有重要意义。提出一种基于缺陷局部内共振的界面脱黏损伤识别方法,通过建立黏接界面局部缺陷的双自由度非线性模型,利用多尺度方法分析了界面脱黏缺陷局部内共振产生机理,确定内共振损伤识别方法需要特定的激励条件;以铝梁黏接结构为试验对象,基于表面粘贴的压电作动/传感晶片,产生不同频率和幅值的激励信号,对传感晶片响应信号进行频谱分析,通过缺陷局部2∶1内共振出现特有的饱和现象对黏接界面脱黏损伤进行有效识别。仿真与试验结果表明,内共振饱和现象需要特定的激励条件,能够有效放大结构局部缺陷的非线性信号特征,提高了噪声干扰下的黏接结构界面脱黏非线性损伤的检测能力。

Absorbing Interface Conditions for the Simulation of Wave Propagation on Non-Uniform Meshes

We proposed absorbing interface conditions for the simulation of linear wave propagation on non-uniform meshes.Based on the superposition principle of second-order linear wave equations,we decompose the interface condition problem into two subproblems around the interface:for the first one the conventional artificial absorbing boundary conditions is applied,while for the second one,the local analytic solutions can be derived.The proposed interface conditions permit a two-way transmission of low-frequency waves across mesh interfaces which can be supported by both coarse and fine meshes,and perform a one-way absorption of high-frequency waves which can only be supported by fine meshes when they travel from fine mesh regions to coarse ones.Numerical examples are presented to illustrate the efficiency of the proposed absorbing interface conditions.

Local Discontinuous Galerkin Method for Parabolic Interface Problems

In this paper, the minimal dissipation local discontinuous Galerkin method is studied to solve the parabolic interface problems in two-dimensional convex polygonal domains. The interface may be arbitrary smooth curves. The proposed method is proved to be L2 stable and the order of error estimates in the given norm is O（h｜logh｜^1/2）. Numerical experiments show the efficiency and accuracy of the method.

考虑局部挤压的盖梁不落地支架牛腿受力分析

后插梢棒式剪力销-分配梁是目前常用的盖梁模板不落地支架结构体系,目前该不落地支架结构体系的受力分析中常将各构件之间视为密贴接触,忽略了牛腿预留孔与后插钢梢棒之间因施工可行性而采用的不等径设计,以及该设计将导致的不等径圆弧面局部挤压接触问题。采用三维有限元分析了不同施工荷载条件下不落地支架牛腿与钢梢棒的局部接触界面和内力分布,并针对整体和局部强度不足的问题提出结构补强建议。

A High Order Sharp-Interface Method with Local Time Stepping for Compressible Multiphase Flows

In this paper,a new sharp-interface approach to simulate compressible multiphase flows is proposed.The new scheme consists of a high order WENO finite volume scheme for solving the Euler equations coupled with a high order pathconservative discontinuous Galerkin finite element scheme to evolve an indicator function that tracks the material interface.At the interface our method applies ghost cells to compute the numerical flux,as the ghost fluid method.However,unlike the original ghost fluid scheme of Fedkiw et al.[15],the state of the ghost fluid is derived from an approximate-state Riemann solver,similar to the approach proposed in[25],but based on a much simpler formulation.Our formulation leads only to one single scalar nonlinear algebraic equation that has to be solved at the interface,instead of the system used in[25].Away from the interface,we use the new general Osher-type flux recently proposed by Dumbser and Toro[13],which is a simple but complete Riemann solver,applicable to general hyperbolic conservation laws.The time integration is performed using a fully-discrete one-step scheme,based on the approaches recently proposed in[5,7].This allows us to evolve the system also with time-accurate local time stepping.Due to the sub-cell resolution and the subsequent more restrictive time-step constraint of the DG scheme,a local evolution for the indicator function is applied,which is matched with the finite volume scheme for the solution of the Euler equations that runs with a larger time step.The use of a locally optimal time step avoids the introduction of excessive numerical diffusion in the finite volume scheme.Two different fluids have been used,namely an ideal gas and a weakly compressible fluid modeled by the Tait equation.Several tests have been computed to assess the accuracy and the performance of the new high order scheme.A verification of our algorithm has been carefully carried out using exact solutions as well as a comparison with other numerical reference solutions.The material interface is resolved sharply and accurately without spurious oscillations in the pressure field.

电子式高压互感器数字接口的设计及实现

介绍了IEC60044-8和IEC61850中规定的电子式互感器数字输出接口的特性,并设计了一种基于以太网的通信模块以实现此功能。该方案采用基于单片机的嵌入式硬件平台,利用RTL8029AS实现以太网物理层和链路层的大部分功能,并采用TCP/IP协议进行数据传输和系统维护,具有设计简单、维护方便、传输速率快等优点,能够满足变电站自动化、网络化发展对电子式互感器的要求。