A NEW SYNCHRONOUS DIGITAL HIERARCHICAL BI-DIRECTIONAL RING CAPACITY DESIGN ALGORITHM BASED ON THE SHORTEST-ROUTE TRAFFIC MATRIX

In this paper, the concept of the Shortest-Route Traffic Matrix(SRTM) was first presented, and the generalized formula for computing ring capacity requirement in use of SRTM is given. Then, a new capacity design algorithm which is based on SRTM was presented for Synchronous Digital Hierarchical(SDH) Bi-directional Self-Healing Ring (BSHR). The algorithm simulation results demonstrate that this algorithm is very efficient for SDH BSHR capacity design and can make less project investment and make high utilization of lines and equipment. By means of the algorithm in this paper, capacity optimization assignment for SDH Hierarchical Self-Healing Ring (HSHR) and for ATM Virtual Path (VP)-based Self-Healing Ring (SHR) is also discussed.

Digital Twin Modeling Enabled Machine Tool Intelligence:A Review

Machine tools,often referred to as the“mother machines”of the manufacturing industry,are crucial in developing smart manufacturing and are increasingly becoming more intelligent.Digital twin technology can promote machine tool intelligence and has attracted considerable research interest.However,there is a lack of clear and systematic analyses on how the digital twin technology enables machine tool intelligence.Herein,digital twin modeling was identified as an enabling technology for machine tool intelligence based on a comparative study of the characteristics of machine tool intelligence and digital twin.The review then delves into state-of-the-art digital twin modelingenabled machine tool intelligence,examining it from the aspects of data-based modeling and mechanism-data dual-driven modeling.Additionally,it highlights three bottleneck issues facing the field.Considering these problems,the architecture of a digital twin machine tool(DTMT)is proposed,and three key technologies are expounded in detail:Data perception and fusion technology,mechanism-data-knowledge hybrid-driven digital twin modeling and virtual-real synchronization technology,and dynamic optimization and collaborative control technology for multilevel parameters.Finally,future research directions for the DTMT are discussed.This work can provide a foundation basis for the research and implementation of digital-twin modeling-enabled machine tool intelligence,making it significant for developing intelligent machine tools.

Efficient Digital Twin Placement for Blockchain-Empowered Wireless Computing Power Network

As an open network architecture,Wireless Computing PowerNetworks(WCPN)pose newchallenges for achieving efficient and secure resource management in networks,because of issues such as insecure communication channels and untrusted device terminals.Blockchain,as a shared,immutable distributed ledger,provides a secure resource management solution for WCPN.However,integrating blockchain into WCPN faces challenges like device heterogeneity,monitoring communication states,and dynamic network nature.Whereas Digital Twins(DT)can accurately maintain digital models of physical entities through real-time data updates and self-learning,enabling continuous optimization of WCPN,improving synchronization performance,ensuring real-time accuracy,and supporting smooth operation of WCPN services.In this paper,we propose a DT for blockchain-empowered WCPN architecture that guarantees real-time data transmission between physical entities and digital models.We adopt an enumeration-based optimal placement algorithm(EOPA)and an improved simulated annealing-based near-optimal placement algorithm(ISAPA)to achieve minimum average DT synchronization latency under the constraint of DT error.Numerical results show that the proposed solution in this paper outperforms benchmarks in terms of average synchronization latency.

轴承圈尺寸检测线虚拟调试不同步问题研究

虚拟调试过程中存在虚拟或真实控制器与虚拟模型数据不同步的问题,这导致了虚拟工艺流程的混乱,严重影响虚拟调试系统的质量,并使数字孪生系统产生了虚实不同步的问题。以轴承圈尺寸检测线为例,设计了一种基于机电一体化概念设计(Mechatronics Concept Designer,MCD)的虚拟调试系统,分析了虚拟调试系统不同步问题,设计了MCD内外部延迟试验,在对现有解决方案分析解释的基础上,提出了考虑MCD内外部延迟的解决方案。试验表明,该解决方案较好地实现了虚拟调试系统与数字孪生系统的虚实同步。

基于电力线载波通信的智慧园区电力物联网精准时间同步方法

智慧园区各类新兴业务在电力物联网(power internet of things,PIo T)设备提供的数据支持下开展。这些业务具有严格的时间同步要求。如何在现有电力线载波通信(power line carrier,PLC)的基础上实现高精度、高可靠时间同步成为关键问题。针对上述问题,首先,该文建立基于PLC的智慧园区电力物联网精准时间同步网络模型,根据改进精准时间协议(precision time protocol,PTP)计算同步误差,在此基础上,建立基于数字锁相环的频率偏移补偿模型,降低累积误差;其次,提出站点(station,STA)时间同步误差最小化问题;最后,提出基于经验匹配的电力物联网精准时间同步算法,通过调整时间同步匹配成本,优化STA的时间同步路径选择策略。仿真结果表明,所提方法能有效提高时间同步精度。

基于数字李生的船舶制造车间监视系统的构建

为解决船舶制造车间生产信息不透明、设备数据采集困难等问题,基于Unity物理平台设计了数字李生船舶制造车间监控系统。针对监视系统中船舶虚拟车间的构造、多源异构数据采集的数据传输方式、由数据驱动的虚实同步方法,以及数据可视化等关键步骤进行了阐释。实验设计船舶制造小组立焊接流水线生产过程的实时监控系统,完成了焊接流水线的3D场景复现以及在李生车间中对现实车间的生产监控,并通过虚实车间一致性验证了系统的可行性。

铁路建设单位数字化转型评价指标体系及应用

随着数字经济在我国社会经济发展中的作用日益凸显,数字化转型已成为企业适应数字经济发展、“弯道超车”的必然选择,而针对企业数字化转型效果的评价也在转型过程中发挥着重要作用。本文在现有数字化转型评价体系研究基础上,结合铁路建设单位数字化转型现状及特点,分析影响铁路建设单位数字化转型的关键因素,选择数字化管理、数字化基础、数字化业务、数字化成效4个维度,构建包括12类二级指标、38个三级指标的铁路建设单位数字化转型评价指标体系,通过层次分析法和专家评分法确定不同层级指标的权重,并以某H铁路建设单位为案例,基于CMMM成熟度评估模型实现铁路建设单位数字化水平的量化,为指导铁路建设单位的数字化转型实践、明确转型方向提供依据。

基于Digital 21230芯片的数字图像监控系统

建立了一种适合于高速信道的新一代数字图像监控系统，并就涉及的关键技术和实现方法进行了讨论。采用Ｄｉｇｉｔａｌ２１２３０芯片硬件实现视音频ＭＰＥＧ－１标准的实时压缩与解压缩，软件上基于Ｗｉｎｄｏｗｓ９ｘ／ＮＴ平台用ＶｉｓｕａｌＣ＋＋开发了一套完整的视音频编解码控制、同步传输和系统多功能操作等应用程序。

Synchronization of Digital Chaos in Secure Communication Systems

The theories of synchronization based on secure communications using digital chaos are presented. A new synchronous method-cycles-interval Pulse drive is developed and realized. Experimental results show it is available, and in order to reduce synchronous noise, a method using model references solves the ratio of signal power to noise power, so the secure communication system can be realized.

Digital Communication Using Multi-mode Chaotic Lasers

The digital communication in a system of two multi-mode solid state chaotic lasers is investigated theoretically. If the usual method working well in a single-mode laser system is applied to a multi-mode laser system, the memory effect of the two nearest digits can cause high rate of mistakes when the digits are decoded through the subtraction of receiver output from the transmittal. By introducing the deviations of two nearest maximum and minimum fluctuationsof the signal to decode the digit, the message can be decoded correctly. Also, this communication method does not critically depend on the quality of the chaotic synchronization of the two multi-mode lasers.

Position Sensorless Control for Permanent Magnet Synchronous Motor Using Sliding Mode Observer

An approach of position sensorless control for permanent magnet synchronous motor （ PMSM ） is put forward based on a sliding mode observer. The mathematical model of PMSM in a stationary αβ reference frame is adopted, and the system is controlled by the digital signal processor （ DSP; TMS320LF2407 according to the control achieve closed loop operation of the motor, the stator theory of sliding mode observer. In order to magnetic field should be vertical with the rotor magnetic field and be synchronous with rotor rotating, so the position and speed of PMSM is estimated in real time and the estimated position is modified continuously. The simulation results indicate that the proposed observer has high precision is more robust to the parametric variation and load in estimation of PMSM position and speed, and torque disturbance.

Research on synchronous measurement technique of temperature and deformation fields using multispectral camera with bilateral telecentric lens

The hot-section parts easily occur the creep-fatigued interaction under the condition of mechanicalthermal coupled load during the period of service, which may lead to the damage of the parts, and therefore, the measurement and characterization of thermal-deformed fields of the parts are important to understand its damage process. Aiming at relevant demand, the bilateral telecentric-multispectral imaging system was established, the research of synchronous measurement technique of the temperature and deformation fields was developed. On the one hand, the measurement technology for surface temperature of the object was developed using the two-color images captured by the multispectral camera with bilateral telecentric lens and combined with colorimetric method. On the other hand, the 2 D-DIC measurement technique of the multispectral camera was developed by conducting digital image correlation analysis using the blue light images before and after deformation, which can measure the high temperature deformation field of the object(the blue light images were filtered by multispectral camera).Results showed that the bilateral telecentric lens is used to replace the ordinary optical lens for imaging,which can effectively eliminate the distortion of the multispectral imaging system. Since the temperature measurement process of this measurement system is little affected by the emissivity of the object, therefore, it has excellent robustness. The thermal expansion coefficients of the nickel alloys are evaluated at the temperature ranges of 700–1000℃, indicating this system can achieve the synchronous and precise measurement of the temperature and deformation fields of the object.

Digital communication of two-dimensional messages in a chaotic optical system

The digital communication of two-dimensional messages is investigated when two solid state multi-mode chaotic lasers are employed in a master-slave configuration. By introducing the time derivative of intensity difference between the receiver （carrier） and the transmittal （carrier plus signal）, several signals can be encoded into a single pulse. If one signal contains several binary bits, two-dimensional messages in the form of a matrix can be encoded and transmitted on a single pulse. With these improvements in secure communications using chaotic multi-mode lasers, not only the transmission rate can be increased but also the privacy can be enhanced greatly.

Synchronization of spatiotemporal chaotic systems and application to secure communication of digital image

Coupled map lattices （CMLs） are taken as examples to study the synchronization of spatiotemporal chaotic systems. In this paper, we use the nonlinear coupled method to implement the synchronization of two coupled map lattices. Through the appropriate separation of the linear term from the nonlinear term of the spatiotemporal chaotic system, we set the nonlinear term as the coupling function and then we can achieve the synchronization of two coupled map lattices. After that, we implement the secure communication of digital image using this synchronization method. Then, the discrete characteristics of the nonlinear coupling spatiotemporal chaos are applied to the discrete pixel of the digital image. After the synchronization of both the communication parties, the receiver can decrypt the original image. Numerical simulations show the effectiveness and the feasibility of the proposed program.

A synchronization scheme for multimedia retrieval in digital libraries over cellular radio networks

Recent advances in wireless mobile computing, digital library, and distributed multimedia technologies are stimulating the development of mobile multimedia digital library systems （ M2DLS） that allow mobile clients to access multimedia material anywhere and anytime over a cellular radio network. This paper addresses the problem of providing synchronized multimedia retrieval in these sys- tems. An efficient inter-media synchronization scheme called wireless prioritized feedback （WPF） for mobile multimedia on-demand retrieval in digital library systems over CDMA cellular radio networks in the absence of synchronized clocks is presented. In the WPF scheme, base stations use preferential lightweight message called feedback units transmitted by mobile mediaphones to detect and correct asynchronies. The algorithm is described with pseudo code, and experiments are described to demonstrate the efficiency of WPF.

A 5M Synchronization Mechanism for Digital Twin Shop-Floor

In recent years,as a promising way to realize digital transformation,digital twin shop-floor(DTS)plays an impor-tant role in smart manufacturing.The core feature of DTS is the synchronization.How to implement and maintain the synchronization is critical for DTS.However,there is still a lack of a common definition for synchronization in DTS.Besides,a systematic synchronization mechanism for DTS is strongly needed.This paper first summarizes the defi-nition and requirements of synchronization in DTS,to clarify the understanding of synchronization in DTS.Then,a 5M synchronization mechanism for DTS is proposed,where 5M refers to multi-system data,multi-fidelity model,multi-resource state,multi-level state,and multi-stage operation.As a bottom-up synchronization mechanism,5M synchronization mechanism for DTS has the potential to support DTS to achieve and maintain physical-virtual state synchronization,and to realize operation synchronization of DTS.The implementation methods of 5M synchronization mechanism for DTS are also introduced.Finally,the proposed synchronization mechanism is validated in a digital twin satellite assembly shop-floor,which proves the effectiveness and feasibility of the mechanism.

直面挑战:审计师数字化专长是否有助于提高审计质量?

借鉴审计师行业专长的度量方法,将数字化客户占比较高的审计师定义为数字化专长审计师,并检验在数字化变革过程中,积极参与数字化审计并取得数字化审计经验的审计师是否能够取得更好的审计结果。结果发现数字化审计专长审计师在数字化市场领域能够带来更优的审计质量,并且他们的特殊技能带来的积极作用能够被资本市场的投资者和分析师识别和认可(股价同步性更低且分析师预测更精准)。该结论为在数字化变革中,审计师如何能动应对大样本档案提供了证据,并为实务中事务所发展数字化审计提供了一些启示。

A preliminary study on criteria weights for a library's digital resource selection:From the viewpoints of both users and librarians

Through investigating both users' and librarians' perceptions of the relative importance of the major criteria governing the selection of digital resources, we attempted to develop a criterion weight framework for a library's selection of digital resources, which can meet both the users' requirements and the library's goal of developing digital collections. The respective weight of each specific criterion is decided through the Analytic Hierarchy Process(AHP) Method. The findings of this study indicate that, when assigning weights to the selection criteria, it is important to consult the opinions of a wide crosssection of people, especially the views of different users. As a result, the digital resource selection system characterized by the criteria weights can reflect more comprehensively the users' requirements, and meanwhile it enables librarians' more rational selection of digital resources.

政务服务数字人:理论诠释、实践困境与因应路径

不同技术条件决定着政务服务方式及其有效程度。当前,集成了众多新技术特征的数字人,为政务服务又一次转型升级提供了机遇,也提出了挑战。理解政务服务数字人不仅是认识政务元宇宙的重要前提,更是把握数智化发展趋势的关键。本研究从信息、服务和系统三个方面出发,构建理论框架对实践中的政务服务数字人进行透视,发现其在信息丰富性、服务可供性和交互同步性方面具有显著优势。通过调研发现,我国政务服务数字人在建设管理、责任界定、技术标准、数据共享与应用场景等方面存在明显短板,并有针对性地提出摆脱实践困境的对策建议。

Problems Related to Excitation Winding Surface Temperature Measurement of a Salient Pole Synchronous Generator in Rotation

This paper addresses some of the problems related to direct surface temperature measurement of a salient pole synchronous generator excitation winding in rotation. Excitation winding temperature is used for determining the dynamic limit in a PQ diagram. The paper also addresses procedures of improving the accuracy of surface temperature measurement using the contact DS 18B20 digital temperature probes. The paper also provides experimental results of direct temperature measurement of the excitation winding surface conducted in the salient pole synchronous generator in the rotation.