RBFs Meshless Method of Lines for the Numerical Solution of Time-Dependent Nonlinear Coupled Partial Differential Equations

In this paper a meshless method of lines is proposed for the numerical solution of time-dependent nonlinear coupled partial differential equations. Contrary to mesh oriented methods of lines using the finite-difference and finite element methods to approximate spatial derivatives, this new technique does not require a mesh in the problem domain, and a set of scattered nodes provided by initial data is required for the solution of the problem using some radial basis functions. Accuracy of the method is assessed in terms of the error norms L2, L∞ and the three invariants C1, C2, C3. Numerical experiments are performed to demonstrate the accuracy and easy implementation of this method for the three classes of time-dependent nonlinear coupled partial differential equations.

A low dead time vernier delay line TDC implemented in an actel flash-based FPGA

In this paper,a high precision vernier delay line(VDL) TDC(Time-to-Digital Convertor) in an actel flash-based Field-Programmable-Gate-Arrays A3PE1500 is implemented,achieving a resolution of 16.4-ps root mean square value or 42-ps averaged bin size.The TDC has a dead time of about 200 ns while the dynamic range is 655.36 μs.The double delay lines method is employed to cut the dead time in half to improve its performance.As the bin size of the TDC is dependent on temperature,a compensation algorithm is adopted as temperature drift correction,and the TDC shows satisfying performance in a temperature range from –5℃ to +55℃.

Real-time Performance Evaluation of Line Topology Switched Ethernet

Recently,switched Ethernet has become an active area of research because of its wide uses in industry.However,its uses have various real-time constraints on data communications.This paper analyzes the performance of the line topology switched Ethernet as a data acquisition network.Network calculus theory,which has been successfully applied to assess the real-time performance of packet-switched networks,is used to analyze the networks.To properly describe the activity of switches,a novel approach of modeling data flows into or out of switches is addressed.Based on our model,a concisely analytical expression of the maximal end-to-end delay in line topology switched Ethernet is derived.Finally,the relative simulation results are demonstrated.These results agree well with the analytical results,and thus they validate the data flow modeling techniques.

Genetic Algorithm for Concurrent Balancing of Mixed-Model Assembly Lines with Original Task Times of Models

The growing global competition compels manufacturing organizations to engage themselves in all productivity improvement activities. In this direction, the consideration of mixed-model assembly line balancing problem and implementing in industries plays a major role in improving organizational productivity. In this paper, the mixed model assembly line balancing problem with deterministic task times is considered. The authors made an attempt to develop a genetic algorithm for realistic design of the mixed-model assembly line balancing problem. The design is made using the originnal task times of the models, which is a realistic approach. Then, it is compared with the generally perceived design of the mixed-model assembly line balancing problem.

Critical Length Criterion and the Arc Chain Model for Calculating the Arcing Time of the Secondary Arc Related to AC Transmission Lines

The prompt extinction of the secondary arc is critical to the single-phase reclosing of AC transmission lines, including half-wavelength power transmission lines. In this paper, a low- voltage physical experimental platform was established and the motion process of the secondary arc was recorded by a high-speed camera. It was found that the arcing time of the secondary arc rendered a close relationship with its arc length. Through the input and output power energy analysis of the secondary arc, a new critical length criterion for the arcing time was proposed. The arc chain model was then adopted to calculate the arcing time with both the traditional and the proposed critical length criteria, and the simulation results were compared with the experimental data. The study showed that the arcing time calculated from the new critical length criterion gave more accurate results, which can provide a reliable criterion in term of arcing time for modeling and simulation of the secondary arc related with power transmission lines.

Locating the position of objects in non-line-of-sight based on time delay estimation

Non-line-of-sight imaging detection is to detect hidden objects by indirect light and intermediary surface（diffuser）.It has very important significance in indirect access to an object or dangerous object detection, such as medical treatment and rescue. An approach to locating the positions of hidden objects is proposed based on time delay estimation. The time delays between the received signals and the source signal can be obtained by correlation analysis, and then the positions of hidden objects will be located. Compared with earlier systems and methods, the proposed approach has some modifications and provides significant improvements, such as quick data acquisition, simple system structure and low cost, and can locate the positions of hidden objects as well： this technology lays a good foundation for developing a practical system that can be used in real applications.

Mitigating Time Interval Error (TIE) in High-Speed Baseband Digital Transports: Design for Delay Compensation at Baseband Infrastructure of Smart-Phones Using Fractal Dispersive Delay-Lines

A major concern in modern smart-phones and hand-held devices is a way of mitigating the time interval error (TIE) perceived at high-speed digital transits along the traces of the circuit-board (rigid and or flexible) used in baseband infrastructures. Indicated here is a way of adopting a planar fractal inductor configuration to improvise the necessary time-delay in the transits of digital signal phase jitter and reduce the TIE. This paper addresses systematic design considerations on fractal inductor geometry commensurate with practical aspects of its implementation as delaylines in the high-speed digital transports at the baseband operations of smart-phone infrastructures. Experimental results obtained from a test module are presented to illustrate the efficacy of the design and acceptable delay performance of the test structure commensurate with the digital transports of interest.

面向电力线通信的基于Mitchell算法的OFDM同步检测方法

为了提高电力线通信系统中OFDM定时同步的准确度,文章基于低压电力线宽带载波通信互联互通技术规范下的物理层通信协议,提出了一种基于Mitchell算法的电力线载波通信符号定时算法。与理论本地互相关同步算法相比,文章的算法不需要进行乘法运算,易于硬件实现。与简化的单比特量化算法相比,该算法同步检测结果更加准确,峰值旁瓣更小,在低信噪比条件下符号定时更加准确。

Research of Dynamic Material Handling in an Automobile General Assembly Line Based on Real-time Information

The status of material delivery of an automobile general assembly line is analyzed, and the technique to achieve the real-time tracking of assembly status information is proposed based on RFID（ Radio Frequency Identification）. Thus the consumption of line-side buffer is obtained dynamically, then the type and quantity of needed material are fed back to the subsystem of material handling; the algorithm for determining the best time departure time of delivery driver based on minimizing of total time penalty function is proposed. This approach makes the material amount of a single delivery trip maximized and improves the efficiency of delivery drivers significantly in the case of does not affect the assembly line normal throughput. Additionally, although this dynamic material handling method is developed for the automobile assembly plant, it should be pointed out that this method is also applicable to other mixed model assembly plants such as electronics, semiconductor and aerospace industry.

西门子Smart line-IE系列人机界面应用案例

介绍了怎样解决西门子Smart line-IE系列人机界面因内部不带时钟电池,断电重新上电后时间不能同步的问题;以及程序下载的基本方法及注意事项。

浅水浮式风电结构非线性波浪荷载及动力响应特性研究

浮式风电结构在浅水海域中承受的波浪荷载及运动响应表现出非线性特征,对浮式风电安全性提出很高要求。本文建立了风机-浮式基础-系泊系统耦合分析模型,对于不同水深、不同波浪荷载计算方法下的频域水动力系数和时域计算结果分别进行了对比,讨论了水深以及波浪荷载计算方法对浮式风电结构响应和系泊张力的影响。结果表明:浮式风电结构的水动力性能和动力响应随水深变化显著。水深较浅时,浮体响应和系泊张力的低频部分明显增大,二阶波浪荷载的影响更加显著。同时,Newman近似方法与全二次传递函数方法相比,在浅水条件下会明显低估二阶波浪荷载效应,进而影响平台响应和系泊张力的分析。

An On-Line Scheduler over Hard Real-Time Communication System

By thorough research on the prominent periodic and aperiodic scheduling algorithms,anon-line hard real-time scheduler is presented,which is applicable to the scheduling of packets over a link.This scheduler,based on both Rate Monotonic,pinwheel scheduling algorithm Sr and Polling Serverscheduling algorithms,can rapidly judge the schedulability and then automatically generate a bus tablefor the scheduling algorithm to schedule the packets as the periodic packets.The implementation of thescheduler is simple and easy to use,and it is effective for the utilization of bus link.The orderly executionof the bus table can not only guarantee the performance of the hard real time but also avoid the blockageand interruption of the message transmission.So the scheduler perfectly meets the demand of hard real-time communication system on the field bus domain.

面向流程制造的数字孪生车间可视化监控系统研究

为了解决流程制造过程监控实时性差、准确性不足的问题,在数字孪生技术迅速发展且与制造业结合愈发紧密的背景下,提出基于生产要素数据、生产工艺流程与多工序设备实体对象的数字孪生车间可视化监控系统架构。从要素、状态、运行逻辑等多个维度对多工序耦合生产线实体对象进行孪生建模,基于OPC UA统一架构的数据采集传输,虚拟车间的实时驱动等关键技术,实现了流程制造设备状态、生产要素工艺全流程三维可视化监控。基于某流程制造企业制丝生产试验线开展了应用验证,为提升流程制造过程中全生产要素的预见性、联动性、自治性提供了方法和实现途径。

Lane Line Detection Based on Improved PINet

Accurate perception of lane line information is one of the basic requirements of unmanned driving technology, which is related to the localization of the vehicle and the determination of the forward direction. In this paper, multi-level constraints are added to the lane line detection model PINet, which is used to improve the perception of lane lines. Predicted lane lines in the network are predicted to have real and imaginary attributes, which are used to enhance the perception of features around the lane lines, with pixel-level constraints on the lane lines;images are converted to bird’s-eye views, where the parallelism between lane lines is reconstructed, with lane line-level constraints on the predicted lane lines;and vanishing points are used to focus on the image hierarchy, with image-level constraints on the lane lines. The model proposed in this paper meets both accuracy (96.44%) and real-time (30 + FPS) requirements, has been tested on the highway on the ground, and has performed stably.

基于数字孪生的拖拉机混流装配智能排产仿真评价

车间排产对提高车间的效率至关重要,智能排产可以极大提高加工的自动化和智能化水平。但传统生产过程中大多采用固定的工时数据进行产线作业时间估算,而拖拉机混流装配以工人作业为主,工人作业时间不固定甚至存在较大差异。为满足智能排产要求,提出通过数字孪生车间对生产计划进行仿真评价以增强与实际车间的交互与反馈。搭建与现场拖拉机装配线一致的数字孪生三维模型场景及人机交互界面,根据MES系统中的过点信息实现装配线模型实时驱动,建立了一个拓展性强、可灵活复用的数字孪生系统。分析了生产计划评价指标,提出通过生产计划管理系统与孪生装配线的交互反馈,实现对基于数字孪生装配线的生产计划仿真运行及评价。通过数字孪生装配线采集到的实际工时仿真运行生产计划,可以得到优化后的生产计划。将低产、正常和高产月份各5 d内的实际生产计划与本系统生成的计划进行对比,结果表明本系统仿真评价后得到的生产计划更优越。

端接复杂电路传输线网络的电磁耦合时域并行计算方法

针对端接复杂电路传输线(TL)网络的电磁耦合问题,仍缺乏高效的场路协同仿真技术。该文将传输线方程与时域有限差分(FDTD)方法、诺顿定理和置换定理以及NGSPICE软件相结合,并引入消息传递接口(MPI)并行技术,提出一种高效的时域混合并行算法(FDTDTL-NGSPICE)。首先,根据诺顿定理和置换定理,将传输线网络分解为传输线子系统和复杂电路子系统,并构建对应的等效电路模型。然后,使用FDTDTL并行算法计算传输线子系统沿线各点的电压和电流,并获取对应诺顿等效电路的电流源和等效导纳大小。最后,使用NGSPICE对复杂电路子系统进行传导干扰分析,获得复杂电路各元件上的瞬态响应,并将端口电压反馈给传输线子系统作为边界,实现传输线网络电磁耦合的场线路联合协同仿真。通过对3类典型场景的计算实例,分别使用时域混合并行算法和电磁仿真软件CST电缆工作室(CS)进行数值模拟并对比,验证所提算法的置信度。

考虑暂态过电压特性的架空输电线路雷击故障时空预警方法

针对运行环境复杂多变,故障率持续居高不下,雷击故障占比较大,并具有随机性与无法预知性的问题,提出考虑暂态过电压特性的架空输电线路雷击故障时空预警方法。深入解析雷击机理与雷电流,确定雷击(感应雷与直击雷)输电线路暂态过电压计算方式,通过小波多分辨率分解算法处理输电线路暂态信号,评估暂态过电压在信号频段中的能量比,识别累计故障,判断雷击点与故障点是否一致,利用单端检测确定雷击点的位置,完成架空输电线路雷击故障的时空预警。实验数据显示,在不同实验组别背景下,当阈值pΔ取值为9.3时,雷击故障识别精度达到最大值92%,雷击点定位精度高达80%。可以获得精准的雷击故障识别结果与雷击点定位结果,充分证实了提出方法具备较好的雷击故障时空预警效果。

同心分注井在线电动验封仪研制及应用

随着油田开发的不断深入,分层注水仍是补充地层能量、实现油田稳产、提高采收率的主要开发方式,原有同心分层注水井验封技术存在仪器定位难、密封件易损坏、验封效率低等问题,采用设计和试验相结合的研究方法,研制了同心分注井在线电动验封仪,并配套测调、验封一体多功能地面控制系统,集成流量、上/下压力等多参数测试技术,实现了一次下井、多层验封测试。试验表明,验封仪的坐卡/解卡性能、胶筒坐封/解封性能、整机承压能力、密封承压能力均能达到要求,现场应用效果良好,有效解决了验封效率不高等问题,提高了分层注水测试效率和合格率,为提升油田精细注水效果提供了可靠的工艺技术。

R冷链企业混流生产线排产优化研究

以R冷链企业混流生产线为研究对象,以闲置时间与超载时间之和最小为目标建立排产优化模型。同时,考虑模型混流装配线投产的特性,采用遗传算法对模型求解。结果表明,混流生产线的投入产出比由75.5%提高至85.0%,日产量提高了11.26%,可以为冷链企业提高产能提供一定的参考。

光频梳下变频信号光纤延时频率恢复方法

针对光频梳下变频信号接收过程中存在的频率信息丢失问题,提出了一种基于频率-相位映射的信号频率恢复方法,该方法使用可调光纤延迟线在两路光频梳变频链路之间产生一组固定已知的时延,时延在信号原始频率与下变频信号相位差之间建立映射关系,利用该映射关系可以从测得的相位差计算出信号的原始频率。分析了时延值等参数对频率恢复的影响,估计了该方法对相位测量不确定度的限值要求,最后给出了该方法具体实施方案中关键参数的设置策略。所有下变频信号的相位差可以通过快速傅里叶变换等数据处理一次性得出,因此该方法的时间代价和计算成本几乎不随着信号个数增加而增加。在不考虑下变频信号混叠的情况下,本文所提出的方法在理论上对处理信号的数量没有限制,因此相比于已有的光频梳下变频信号频率恢复方法,在多信号频率恢复方面更具有优势。