Effect and mechanism of on-chip electrostatic discharge protection circuit under fast rising time electromagnetic pulse

The electrostatic discharge(ESD)protection circuit widely exists in the input and output ports of CMOS digital circuits,and fast rising time electromagnetic pulse(FREMP)coupled into the device not only interacts with the CMOS circuit,but also acts on the protection circuit.This paper establishes a model of on-chip CMOS electrostatic discharge protection circuit and selects square pulse as the FREMP signals.Based on multiple physical parameter models,it depicts the distribution of the lattice temperature,current density,and electric field intensity inside the device.At the same time,this paper explores the changes of the internal devices in the circuit under the injection of fast rising time electromagnetic pulse and describes the relationship between the damage amplitude threshold and the pulse width.The results show that the ESD protection circuit has potential damage risk,and the injection of FREMP leads to irreversible heat loss inside the circuit.In addition,pulse signals with different attributes will change the damage threshold of the circuit.These results provide an important reference for further evaluation of the influence of electromagnetic environment on the chip,which is helpful to carry out the reliability enhancement research of ESD protection circuit.

GrCol-PPFL:User-Based Group Collaborative Federated Learning Privacy Protection Framework

With the increasing number of smart devices and the development of machine learning technology,the value of users’personal data is becoming more and more important.Based on the premise of protecting users’personal privacy data,federated learning(FL)uses data stored on edge devices to realize training tasks by contributing training model parameters without revealing the original data.However,since FL can still leak the user’s original data by exchanging gradient information.The existing privacy protection strategy will increase the uplink time due to encryption measures.It is a huge challenge in terms of communication.When there are a large number of devices,the privacy protection cost of the system is higher.Based on these issues,we propose a privacy-preserving scheme of user-based group collaborative federated learning(GrCol-PPFL).Our scheme primarily divides participants into several groups and each group communicates in a chained transmission mechanism.All groups work in parallel at the same time.The server distributes a random parameter with the same dimension as the model parameter for each participant as a mask for the model parameter.We use the public datasets of modified national institute of standards and technology database(MNIST)to test the model accuracy.The experimental results show that GrCol-PPFL not only ensures the accuracy of themodel,but also ensures the security of the user’s original data when users collude with each other.Finally,through numerical experiments,we show that by changing the number of groups,we can find the optimal number of groups that reduces the uplink consumption time.

The Research of Intelligent Substation Time Synchronization System and the Influence of Its Fault to Relay Protection

The intelligent substation realizes the digitization of information in the whole substation and thus time synchronization system becomes more and more important. This paper introduces time synchronization technology of intelligent substation and puts forward the principles for designing intelligent substation time synchronization system. According to some relay protection malfunction examples caused by time synchronization system fault, analyze the influence of time synchronization system fault to relay protection and correspondingly put forward some improving measures.

Solution Scheme for Time Synchronization of Current Differential Protection between Digital Substations

In digital substations with power transformers, the key to implementation of line differential protection is synchronization of electrical quantities at both two sides. System framework of current differential protection for lines between digital substations is analyzed briefly, as well as the necessity of demand for time synchronization. Principle of time synchronization based on GPS and IEEE1588 PTP (Precision Time Protocol) are introduced. Time synchronization of current differential protection between digital substations based on IEC61850 is discussed. This paper puts forward two solution schemes of time synchronization, analyzes their advantages and disadvantages respectively, and points out that the development direction of time synchronization of differential protection between digital substations is IEEE1588 PTP.

Analysis of travel time, sources of water and well protection zones with groundwater models

This study compares numerical models with analytical solutions in computing travel times and radius of protection zones for a pumping well located in an unconfined aquifer with uniform recharge and in a semi-confined aquifer. Numerical models were capable of delineating protection zones using particle tracking method in both cases. However, protection zones defined by travel time criterion can only protect small percent of source water to the well; large percent of source water is not protected which may pose a risk of pollution of source water to the well. The case study of Leggeloo well field in the Netherlands indicates that although a well field protection area was enforced in 1980 s, elevated nitrate concentration has been monitored in the abstracted water since 1990 s. The analysis of protection areas shows that the current protection area only protects 37.4% of recharge water to the well field. A large protection area must be adopted in order to safeguard the sustainable water supply for the local community.

The Game Analysis of Environmental Protection at Scenic Spots

Game model of environmental protection at scenic spots is established in this paper in order to carry out analysis of the equilibrium between one-time game and infinitely repeated game, disclose the reasons why the environment of scenic spots are destroyed, and propose the countermeasures to ensure the equilibrium of the game. The study also reveals that during the one-time game between tourists and tour operators, it is tour operators' dominant strategy not to control environmental pollution that leads to the destruction of environment at scenic spots. While, during the infinitely repeated game between tourists and tour operators, the realization of Pareto optimality equilibrium (The strategy of tourist is traveling, and the strategy of tour operators are controlling environmental pollution) is dependent upon the choice of players (tourists or operators) of triggering strategy (traveling or controlling environmental pollution). The supervision of the government upon operators can force them to control environmental pollution, which can consequently improve the efficiency of equilibrium in the game, and promote environmental protection at tourism scenic spots and sustainable development of tourism.

Cyber Resilience through Real-Time Threat Analysis in Information Security

This paper examines how cybersecurity is developing and how it relates to more conventional information security. Although information security and cyber security are sometimes used synonymously, this study contends that they are not the same. The concept of cyber security is explored, which goes beyond protecting information resources to include a wider variety of assets, including people [1]. Protecting information assets is the main goal of traditional information security, with consideration to the human element and how people fit into the security process. On the other hand, cyber security adds a new level of complexity, as people might unintentionally contribute to or become targets of cyberattacks. This aspect presents moral questions since it is becoming more widely accepted that society has a duty to protect weaker members of society, including children [1]. The study emphasizes how important cyber security is on a larger scale, with many countries creating plans and laws to counteract cyberattacks. Nevertheless, a lot of these sources frequently neglect to define the differences or the relationship between information security and cyber security [1]. The paper focus on differentiating between cybersecurity and information security on a larger scale. The study also highlights other areas of cybersecurity which includes defending people, social norms, and vital infrastructure from threats that arise from online in addition to information and technology protection. It contends that ethical issues and the human factor are becoming more and more important in protecting assets in the digital age, and that cyber security is a paradigm shift in this regard [1].

Protective Measures for Space Environment of Time-honored Brands——With Xi'an City as a Study Case

Based on the field survey and analysis of representative traditional time-honored shops in Xi'an City,specific measures for protecting their space environment were put forward,and the sustainable preservation and development pattern of such intangible cultural heritages in the future urban development was established.

Application of high temperature heat pipe in hypersonic vehicles thermal protection

In order to develop further the application of high temperature heat pipe in hypersonic vehicles thermal protection, the principles and characteristics of high temperature heat pipe used in hypersonic vehicles thermal protection were introduced. The methods of numerical simulation, theory analysis and experiment research were utilized to analyze the frozen start-up and steady state characteristic of the heat pipe as well as the machining improvement for fabricating irregularly shaped heat pipe which is suitable for leading edge of hypersonic vehicles. The results indicate that the frozen start-up time of heat pipe is long （10 min） and there exists large temperature difference along the heat pipe （47 ℃/cm）, but the heat pipe can reduce the temperature in stagnation area of hypersonic vehicles from 1 926 to 982 ℃ and work normally during 1 000-1 200℃. How to improve the maximum heat transfer capability and reduce the time needed for start-up from frozen state of the heat pipe by optimizing thermostructure such as designing of a novel wick with high performance is the key point in hypersonic vehicles thermal protection of heat pipe.

Comparative Identification of Wellhead Protection Areas for Municipal Supply Wells in Gaza

Groundwater is the only source of fresh water in Gaza Strip while its inhabitants and its water consumption increased rapidly. This study aims at preserving and protecting the groundwater from any pollutants caused by 141 industrial installations through the work of delineation of Wellhead Protection Areas (WHPA) for 47 Municipal Supply Wells in Gaza Governorate boundaries. WHPA has been determined in three different methods: Calculated Fixed-Radius Method (CFR), Analytical Method (AM), and Wellhead Analytic Ele-ment Model (WhAEM2000) which is currently used by the United States Environmental Protection Agency (EPA). These methods mainly depend on the time it takes groundwater to travel a specified horizontal dis-tance. Three well zones were delineated for each municipal production well, the first zone is 50 days time of travel (TOT), the second zone is 2 years TOT and the third zone is 5 years TOT. Different values of the ra-dius of WHPA of each well were obtained using the three methods. Consequently, several industrial installa-tions were laid inside the WHPA according to the radius values. The results show that CFR method is the weakest method because it does not take into account regional groundwater flow, causing a hydraulic gradi-ent. WHPAs identified by these methods may be either too large or too small, resulting in wellhead overpro-tection or under protection. Analytical Method incorporates hydrogeologic characteristics of the aquifer, groundwater flow, and hydrogeologic boundaries into the model. Often produces a WHPA that is smaller than the one produced using CRF. WhAEM2000 method is the best method because it uses a hydrogeologi-cal computer model of groundwater flow and it provides a more accurate delineation of the WHPA. It often produces a smaller area to manage than other methods. The study concluded that all industrial installations located in the WHPA should be carefully checked and investigated by governmental authorities. Mitigation measures for pollutants and licenses for the establishment of any new industrial installations could be based on the delineation of WHPAs using the previously mentioned methods.

A New Analyzing Method of Single Event Latch-Up Protection Circuit Based on Current Comparing and Its Performance Verification

Single event latch-up (SEL) is a significant issue for electronics design in space application, which would cause large currents in electronic devices, and may lead to burning out of devices. A new monitoring circuit based on current-comparing method is designed to protect the electronics away from SEL’s damage in radiation environment. The response time of protection circuit has been analyzed. The signal simulation results indicated that the operating time of the SEL protection circuit is dependent on the action time of current comparator and system application recovery time. The function of the monitoring circuit protection device away from SEL’s damage has validated through experiment at last.

Impact Analyses of Wind Farm on Performances of Transmission Line Relay Protection

A simulation system for power grid with concentrated large-scale wind farm integration is established based on the electro-magnetic transient model of wind turbine equipped with doubly-fed induction generator (DFIG),which is built by real-time digital simulator (RTDS).Using the hardware communication interface of RTDS,a closed-loop testing experiment is accomplished to study the impacts of large-scale wind farms on the existing relay protection devices for wind farm outgoing transmission line.This paper points out problems existing in current relay protection devices as follows:fault phase selector can select unwanted phase due to the changes of fault features caused by special network connection of wind farms;blocking condition for distance protections needs to be re-examined due to the weak power-feed characteristics of wind farms;and power frequency parameter based relay protection devices cannot accurately operate due to the special transient voltage and current characteristics of wind farms during fault period.Results lay the foundation for improving the performances of the existing relay protection device and developing new principle relay protection.

A Portable Multi-functional Real-time Digital Simulator Dedicated to Protective Relay Testing

The paper intfoduces a PC-DSP based real-time digital simulator which is portable in size and aimed at the closed-loop testing of various types of protective relays for their design and application. The simulator can be widely used in not only concerning utilities but also manufacturers and research / certification institutes because of its many functions. The hardware architecture and software implementation of the simulator are described. The main features and functions of the simulator are also

Fault diagnosis and protection of motors in coal shearer

Symmetrical components method is employed in analysis of the characteristic motor faults.Motor protection method is put forward based on detecting positive sequence,negative sequence and zero sequence current.And problems of lack of motor overload capacity in existing mining motor protection system,impact of dynamic current on stage and definite-time delay operation and inaccuracy of criterion phase failure protection are analyzed.The unbalanced faults protection and inverse-time overload protection,which can make protection time change with the current movement,are proposed.The above problems can be solved,and the reliability and intelligent of coal shearer are improved.

Monitor System for Protection Device Based on Embedded RTOS

For the purpose of the monitor system in digital protection, the embedded real-time operating system (RTOS) and the embedded GUI (Graphical User Interface) is introduced to design the monitor system. Combining the necessity and the application value of the operation system, the choice of embedded Linux and Qt/Embedded is completely viable for the monitor system in digital protection for generator-transformer sets. The design with embedded Linux and embedded GUI enriches system information, increases developing efficiency and improve the generality.

Reliable Remote Relay Protection in Smart Grid

As the false trips of remote protection relays are among the main reasons behind cascading blackouts, it is critical to design reliable relay protection. Even though common protection schemes on traditional power systems have been investigated for a few decades, cascading failures in recent years indicate more research needed in this area. Consequently, researchers have proposed agent-based methods on the Smart Grid （SG） to address this issue. However, these existing agent-based methods simply use TCP protocol without considering real-time communication requirements （such as bandwidth and delay）. To deal with this issue, several methods for efficient network resource management are proposed. Furthermore, these existing methods do not consider the potential issues in practical communication networks, which may result in delay violation and trigger relay false trips. We have discussed simple backup solutions in the previous work. In this paper, in addition to network efficiency, we focus on improving the system reliability by exploring known power system information and minimizing the chances of false trips of important remote relays, e.g., defining power line priorities based on their importance. Moreover, to further improve the. system reliability, we also in- vestigate the peer-to-peer protection approaches to address the single point of failure of centralized control center.

基于动作时限曲线拟合思想的含DG型配电网后备保护新方法

分布式电源(distributed generation,DG)的接入可能会改变电力系统的短路电流特性,从而影响到反时限过流保护的选择性和配合关系。为此,提出一种基于动作时限曲线拟合思想的含DG型配电网后备保护新方法。从配电网主保护和后备保护的动作时间差入手,建立曲线拟合模型,并运用梯度下降法对反时限过流保护的动作时限曲线进行优化。通过在优化整定计算中考虑保护的选择性以及DG接入所带来的影响,使优化参数适用于配电网中各分段位置。然后,在配电网中设置两相、三相短路故障,并根据故障位置、类型进行整定参数再调整,最终得到参数的全局最优解。基于PSCAD/EMTDC仿真软件进行仿真分析,验证了所提方法的有效性和实用性。

海上风电低频输电系统快速母线保护

海上风电低频输电系统母线故障后,换流器型电源等效电势与阻抗因控制的切换与调整过程,不再像传统电网可视为恒定。文中理论分析了母线电流差动保护适应性,明确故障控制策略对差动保护灵敏度的影响方式。利用母线区内外故障所对应的故障等效模型不同,提出基于时域全量模型识别的母线保护。该保护原理反映被保护元件自身拓扑的变化,理论上具有不受电源特性影响的优势,同样适用于其他换流器型电网。同时,所提保护在时域中实现,不存在相量提取问题,动作速度快。最后,在PSCAD/EMTDC中搭建了仿真模型,验证了所提母线保护的可靠性和快速性。

我国远程工作模式劳动者权益保护的制度建构完善——从空间要素与时间要素维度分析

远程工作模式预计未来会成为我国一种主要的新的灵活用工形态,相比于传统工作模式,发生劳动从属性显著弱化这一劳动关系深刻变化。在我国,远程工作模式劳动者权益保护面临空间要素与时间要素两个维度的特殊劳动法问题,适用既有劳动法相关制度实现劳动者权益保护存在很大障碍,需要基于对其劳动法理论的分析,对既有劳动法相关制度加以建构完善。建议未来修订我国《劳动合同法》,在第五章增设新的专节“远程工作”。

一种应用于TDMA无线传感网的低能耗同步机制

为了降低时分多址网络中时钟同步所导致的节点能耗,根据节点晶振器件的潜在漂移,提出了一种应用于星型无线传感网的低能耗同步机制。该机制中整个时间轴由长帧组成,每个长帧包含一个同步帧与多个子帧,每个子帧由所有子节点绑定的子时隙构成。根节点在长帧开始时发送同步帧,使得所有子节点时钟同步。每个子时隙增加了相应的保护间隔,有效地避免子节点之间因时钟漂移导致时隙间相互影响,从而最大限度地增加长帧中的子帧数量,降低子节点唤醒进行同步的频率。与传统的TDMA每个子帧均需同步相比,从接收同步帧角度来讲,大幅度减少了子节点能耗。最后,假定晶振频率误差为正态分布的情况下,利用MATLAB进行仿真,验证了该低能耗同步模型公式的正确性,并将仿真情况在CC1310器件构建的星型网上进行了应用验证。