Digital Twin Modeling and Simulation Optimization of Transmission Front and Middle Case Assembly Line

As the take-off of China’s macro economy,as well as the rapid development of infrastructure construction,real estate industry,and highway logistics transportation industry,the demand for heavy vehicles is increasing rapidly,the competition is becoming increasingly fierce,and the digital transformation of the production line is imminent.As one of themost important components of heavy vehicles,the transmission front andmiddle case assembly lines have a high degree of automation,which can be used as a pilot for the digital transformation of production.To ensure the visualization of digital twins(DT),consistent control logic,and real-time data interaction,this paper proposes an experimental digital twin modeling method for the transmission front and middle case assembly line.Firstly,theDT-based systemarchitecture is designed,and theDT model is created by constructing the visualization model,logic model,and data model of the assembly line.Then,a simulation experiment is carried out in a virtual space to analyze the existing problems in the current assembly line.Eventually,some improvement strategies are proposed and the effectiveness is verified by a new simulation experiment.

Digital simulation studies on long transmission line protection based on balance of energy

The protection based balance of energy is a new technique specially proposed for long transmission lines. This technique depends upon the calculation of net energy into the transmission line by two independent methods and comparing them to indicate healthy and faulty conditions. In order to study the performance and feasibility of the protection based on balance of energy, the new protection has been extensively tested by using EMTP on a long transmission line with various configurations and operating conditions (including single pole line, double circuit lines and two phase operation). The results calculated by EMTP show that under any condition of a power system, the proposed technique has excellent performance,the viability even for high resistance ground faults and a short operation time.

An Estimation of Achievable Rate for Digital Transmissions over MIMO Channels

Achievable rate (AR) is significant to communications. As to multi-input multi-output (MIMO) digital transmissions with finite alphabets inputs, which greatly improve the performance of communications, it seems rather difficult to calculate accurate AR. Here we propose an estimation of con-siderable accuracy and low complexity, based on Euclidean measure matrix for given channel states and constellations. The main contribution is explicit expression, non-constraints to MIMO schemes and channel states and constellations, and controllable estimating gap. Numerical results show that the proposition is able to achieve enough accurate AR computation. In addition the estimating gap given by theoretical deduction is well agreed.

Digital television transmission based on asynchronous transfer mode

This paper introduces a method to realize digital television transmission based on asynchronous transfer mode (ATM), a technology based on fast packet switching. Choosing the integral multiple length of an ATM cell payload to equal to the length of an MPEG transport stream packet, an MPEG transport stream packet can be inextenso loaded by several ATM cells and trans-formed into ATM cells. Using ATM virtual connection technology and B-ISDN, the interoperability between ATM and DTV may be realized, and DTV signal transmission may also be realized finally.

Simulation Design of Baseband Optimal Digital Communication System with Non-Ideal Channel

This paper aims to discuss how to effectively suppress intersymbol interference by optimizing the filter design, so as to achieve a distortion-free output effect, and effectively compensate the transmission characteristics of the baseband transmission system in a non-ideal channel environment, so as to minimize the impact of intersymbol crosser. The simulation experiment model of digital optimal baseband transmission and the overall structure of the system are designed based on the Matlab simulation platform, and the parameters of each module in the simulation experiment model are set. The working process and performance of the digital optimal baseband transmission system are simulated, and the conditions and performance of the digital optimal baseband transmission system are verified according to the simulation results.

飞利浦Digital Diagnost系列DR设备工作原理及故障维修

文章介绍了飞利浦Digital Diagnost系列DR设备工作原理和同步通讯信号传输时序,分析了X射线无法曝光、成像失败等故障的原因,有针对性地提出了处理措施,以期为同行提供相关经验。

Phase-stabilized RF transmission system based on LLRF controller and optical delay line

Radio frequency(RF)transmission systems with high-precision phase stability are required by the next generation of particle colliders and light sources.An RF transmission system was designed to meet this requirement.In this system,RF signal generated at the sending end is modulated onto a continuous wave(CW)optical carrier,transmitted through an optical fiber,and demodulated at the receiving end.The phase drift is detected by a digital phase monitor with femtosecond-level accuracy and compensated by a motorized optical fiber delay line(ODL).The measurement results show that the long-term phase drifts can be stabilized to within 100 fs(pk-pk),500 fs(pk-pk),and 1.8 ps(pk-pk)in a 400-meter-long optical fiber over 1 h,24 h,and 10 days,respectively.

Digital Coal Mine Integrated Automation System Based on ControlNet

A three-layer model for digital communication in a mine is proposed. Two basic platforms are discussed: A uniform transmission network and a uniform data warehouse. An actual,ControlNet based,transmission network plat-form suitable for the Jining No.3 coal mine is presented. This network is an information superhighway intended to inte-grate all existing and new automation subsystems. Its standard interface can be used with future subsystems. The net-work,data structure and management decision-making all employ this uniform hardware and software. This effectively avoids the problems of system and information islands seen in traditional mine-automation systems. The construction of the network provides a stable foundation for digital communication in the Jining No.3 coal mine.

A Method of Coding and Decoding in Underwater Image Transmission

A new method of coding and decoding in the system of underwater image transmission is introduced, including the rapid digital frequency synthesizer in multiple frequency shift keying, image data generator, image grayscale decoder with intelligent fuzzy algorithm, image restoration and display on microcomputer.

Controlling the light wavefront through a scattering medium based on direct digital frequency synthesis technology

Phase modulation is a crucial step when the frequency-based wavefront optimization technique is exploited to measure the optical transmission matrix(TM) of a scattering medium. We report a simple but powerful method, direct digital frequency synthesis(DDS) technology to modulate the phase front of the laser and measure the TM. By judiciously modulating the phase front of a He–Ne laser beam, we experimentally generate a high quality focus at any targeted location through a 2 mm thick 120 grit ground glass diffuser, which is commercially used in laser display and laser holographic display for improving brightness uniformity and reducing speckle. The signal to noise ratio(SNR) of the clear round focus is 50 and the size is about 44 μm. Our study will open up new avenues for enhancing light energy delivery to the optical engine in laser TV to lower the power consumption, phase compensation to reduce the speckle noise, and controlling the lasing threshold in random lasers.

Design of intelligent detecting system based on wireless transmission

An intelligent detecting system based on wireless transmission is designed. Its hardware includes the card reading module, the wireless digital transmission module, the LCD module, the random password keyboard module and a 16×16 lattice word database based on e-Flash MM36SB020. Its software is a communication protocol between the central control computer and the entrance management base station. To resolve the conflicting problems occurred during the data transmission, a method of delaying time at random is proposed.

A Flexible ADM-based Optical Relay Transmission System

A flexible ADM-based optical relay transmission system has been developed, which provides one 34Mbps channel, two 8Mbps channels, one monitory channel and one order-wire channel. It is especially suitable for the rural communication networks and the communications in railways, oil pepelines, etc.

Protection Scheme Half Wavelength Transmission Trunk Using Conventional Relay

This paper presents the main results on the use of conventional protection hardware to protect a Half Wavelength Transmission Line, or shortly AC-Link, for possible occurrence of three-phase and single-phase fault during energization maneuver. Lines of these dimensions do not exist today, but in countries of continental size they could be an interesting alternative to HVDC transmission, since the AC-Link has less dependence on Power Electronics technology. The studies on performance and relay settings were implemented using the RTDS real-time simulator. It is important to note that the AC-Link protection for the energization maneuver can be performed with existing hardware on conventional relays.

Application of Spectral Analysis in Multichannel Digital Filter

The paper proposes a multichannel digital filtering method for signal, discusses the application of spectral analysis in the method, and introduces an improved fast transformation formula for Fourier forward and inverse transformation.

Digital Signal Processing for Optical Access Networks

In this paper, we investigate advanced digital signal process ing （DSP） at the transmitter and receiver side for signal pre equalization and postequalization in order to improve spec trum efficiency （SE） and transmission distance in an optical access network. A novel DSP scheme for this optical super Nyquist filtering 9 Quadrature Amplitude Modulation （9 QAM） like signals based on muhimodulus equalization with out post filtering is proposed. This scheme recovers the Ny quist filtered Quadrature PhaseShift Keying （QPSK） signal to a 9QAMlike one. With this technique, SE can be increased to 4 b/s/Hz for QPSK signals. A novel digital superNyquist signal generation scheme is also proposed to further suppress the Nyquist signal bandwidth and reduce channel crosstalk without the need for optical prefiltering. Only optical cou plers are needed for superNyquist wavelengthdivisionmulti plexing （WDM） channel multiplexing. We extend the DSP for shorthaul optical transmission networks by using highorder QAMs. We propose a highspeed Can＇ierless Amplitude/Phase 64 QAM （CAP64 QAM） system using directly modulated la ser （DML） based on direct detection and digital equalization. Decisiondirected least mean square is used to equalize the CAP64QAM. Using this scheme, we generate and transmit up to 60 Gbit/s CAP64QAM over 20 km standard single mode fiber based on the DML and direct detection. Finally, several key problems are solved for real time orthogonalfre quencydivisionmultiplexing （OFDM） signal transmission aml processing. With coherent detection, up to 100 Glfit/s 16 QAMOFDM realtime transmission is possible.

Data compression of displacement fields in digital image correlation by non-integer quantization

To solve the real-time transmission problem of displacement fields in digital image correlation,two compression coding algorithms based on a discrete cosine transform(DCT)and discrete wavelet transform(DWT)are proposed.Based on the Joint Photographic Experts Group(JPEG)and JPEG 2000 standards,new non-integer and integer quantizations are proposed in the quantization procedure of compression algorithms.Displacement fields from real experiments were used to evaluate the compression ratio and computational time of the algorithm.The results show that the compression ratios of the DCT-based algorithm are mostly below 10%,which are much less than that of the DWT-based algorithm,and the computational speed is also significantly higher than that of the latter.These findings prove the algorithm s effectiveness in real-time displacement field wireless transmission.

数字经济赋能长三角制造业高质量发展——空间溢出与机制识别

基于2011—2021年长三角地区41个城市的面板数据,采用主成分分析法和空间杜宾模型等方法实证检验数字经济对长三角制造业高质量发展的赋能效应及多重路径的综合作用效果。结果表明:长三角地区数字经济不仅能显著赋能本地制造业高质量发展,还对邻近地区制造业高质量发展有显著的促进作用,空间溢出效应占比为79.4%;数字经济赋能制造业高质量发展主要依赖于人力资本和物质资本积累,且人力资本与物质资本呈协同效应,消费能力路径与人力资本、物质资本均呈背离效应。

基于数字孪生和深度学习的结构损伤识别

土木工程实际结构损伤状态的时间跨度通常只占总生命周期的一小部分。为解决传统基于数据驱动的结构损伤识别方法缺乏足够多的损伤训练数据的问题,提出结合数字孪生和深度学习的结构损伤识别方法,并应用于实际工程。该方法利用数值仿真模型和在线监测数据构建结构的数字孪生,以获得不同损伤工况下结构动力响应的“大数据”;为了摆脱对外激励信息的依赖,应用经验模态分解法和传递率函数对得到的数据进行预处理;将预处理后的固有模态传递率函数数据作为深度学习的输入进行训练,实现结构的损伤识别。为验证方法的有效性,对实际结构未经训练的监测数据进行分析,结果表明,该方法泛化能力良好,能够有效识别结构损伤状况。通过数字孪生技术解决了传统方法数据匮乏的问题,不需要任何地震信息,利用固有模态传递率函数数据训练的深度神经网络仍能保持较高的损伤识别准确率,二者结合可以使工程结构健康监测更为主动、可靠、高效。

数字经济与农业经济韧性:基于中介效应的机制研究

提升农业经济韧性是实现农业现代化与建设农业强国的重要举措,数字经济为农业经济韧性的提升提供了新路径。文章基于2012-2021年中国30个省区市面板数据,采用双向固定效应模型,分析数字经济对农业经济韧性的直接影响,并利用因果效应法与Bootstrap研究方法分析创新能力在此影响过程中充当的中介作用。研究结果表明:数字经济发展能够显著促进农业经济韧性的提高;进一步研究发现,创新能力在数字经济影响农业经济韧性过程中发挥部分中介作用,数字经济对农业经济韧性的影响存在明显区域差异,对东部地区农业经济韧性赋能效果显著高于中西部地区。基于此,文章提出加强数字经济建设,增强农业经济韧性,提升创新赋能农业经济发展的作用以及实施地区差异化发展政策等建议。