Transmission Section Research Articles

Computing Interarea Oscillation Modes of Large-Scale Power Systems Using Two-Sided Jacobi-Davidson Method

The small-signal stability analysis of power systems concerns the critical modes as well as the modes associated with a physical meaning, e.g., the interarea oscillation modes for weakly connected systems and the modes sensitive to a particular parameter. As the order of the power-system state matrix increases, it becomes more difficult to determine these modes. In this paper, a method is proposed to compute the interarea oscillation modes of large-scale power systems. The deviation in the active power of the transmission section is selected to identify the interarea oscillation modes. Then, the two-sided Jacobi-Davidson method combined with this selection is employed to compute these modes. Participation factors are used to separate the electromechanical oscillation modes. Numerical tests show that the proposed method is valid and efficient.

Proposal and Verification of Function-based Security Protocol for Vehicular Communication System

Not only M2M (Machine-to-Machine) communication but also IoT (Internet of Things) technology has emerged against the backdrop of evolving ICT industry, drawing much attention in all fields including auto industry. Being first adopted in such fields as factories, logistics, meteorology, environment, defense and agriculture and stockbreeding, M2M systems enable devices to communicate automatically with one another and to operate in response to varying conditions. As for vehicles, M2M technology is applied to interactions between internal and external vehicular devices, between vehicles, between vehicles and traffic systems and between vehicles and peripheral devices. Yet, wireless communication systems are prone to hacking attacks in transmission sections. Thus, any attacks on vehicles’ brakes, multiple control systems and engine control parts will put passengers and safety at risk. In this context, many researchers explore the security measures for inter-device communication. This paper designed a protocol for safe communication between vehicular devices using hash function and complex mathematical formulae, and tested it with Casper/FDR, a formal verification tool for protocols. The proposed protocol proved to guard against diverse attacks and to be effectively applicable in practice.

M2M 통신환경에서 안전한 P2P 보안 프로토콜 검증

In parallel with evolving information communication technology, M2M(Machine-to-Machine) industry has implemented multi-functional and high-performance systems, and made great strides with IoT(Internet of Things) and IoE(Internet of Everything). Authentication, confidentiality, anonymity, non-repudiation, data reliability, connectionless and traceability are prerequisites for communication security. Yet, the wireless transmission section in M2M communication is exposed to intruders` attacks. Any security issues attributable to M2M wireless communication protocols may lead to serious concerns including system faults, information leakage and privacy challenges. Therefore, mutual authentication and security are key components of protocol design. Recently, secure communication protocols have been regarded as highly important and explored as such. The present paper draws on hash function, random numbers, secret keys and session keys to design a secure communication protocol. Also, this paper tests the proposed protocol with a formal verification tool, Casper/FDR, to demonstrate its security against a range of intruders` attacks. In brief, the proposed protocol meets the security requirements, addressing the challenges without any problems.

자동차 보안시스템에서 장치간 상호인증 및 정형검증

자동차산업의 발전과 함께 M2M(Machine-to-Machine)통신이 자동차 산업분야에서 많은 관심이 되고 있다. M2M은 기상, 환경, 물류, 국방, 농.축산 등에서 사용하기 시작하여 장비들이 자동으로 상황에 맞추어 통신을 하고 상황에 맞는 동작을 함으로써 운영해가는 시스템이다. 자동차에서도 차량내부 장치 간, 차대 차, 차와 교통시설물, 차와 주변의 환경 등에 적용되고 있다. 그러나 통신시스템의 특성상 전송구간에서 공격자의 공격에 대한 문제가 있으며 자동차의 운행, 제어계통 및 엔진제어 등에 공격자의 공격이 진행되면 안전에 심각한 문제가 발생하게 된다. 따라서 디바이스 간 보안통신에 대한 연구가 활발히 진행되고 있다. 본 논문에서는 차량의 디바이스간 안전한 통신을 위해 해시함수 및 수학적 복잡한 공식을 이용하여 프로토콜을 설계하였으며 프로토콜 정형검증 도구인 Casper/FDR을 이용하여 실험하였으며 제안한 프로토콜이 각종 공격에 안전하게 동작되며 실제 적용할 때 효과적임을 확인하였다. The auto industry has significantly evolved to the extent that much attention is paid to M2M (Machine-to-Machine) communication. In M2M communication which was first used in meteorology, environment, logistics, national defense, agriculture and stockbreeding, devices automatically communicate and operate in accordance with varying situations. M2M system is applied to vehicles, specifically to device-to-device communication inside cars, vehicle-to-vehicle communication, communication between vehicles and traffic facilities and that between vehicles and surroundings. However, communication systems are characterized by potential intruders' attacks in transmission sections, which may cause serious safety problems if vehicles' operating system, control system and engine control parts are attacked. Thus, device-to-device secure communication has been actively researched. With a view to secure communication between vehicular devices, the present study drew on hash functions and complex mathematical formulae to design a protocol, which was then tested with Casper/FDR, a tool for formal verification of protocols. In brief, the proposed protocol proved to operate safely against a range of attacks and be effective in practical application.

(Invited) Synchrotron White-Beam X-Ray Topography Analysis of the Defect Structure of HVPE-GaN Substrates

The defect structure of HVPE-GaN crystals are examined using synchrotron white-beam X-ray topography (SWXRT) and topography results are interpreted and discussed in comparison to reciprocal lattice point broadening from high resolution X-ray diffraction (HRXRD) measurements. Two as-received commercial HVPE-GaN wafers from two different vendors and one HVPE-GaN which was grown on an ammonothermal GaN-seed are investigated in this study. From large-area topography the formation of a cellular defect network is identified for the commercial HVPE-GaN. Large differences in the crystal lattice misorientation deformation (mosaicity) are determined for the different samples by transmission section topography. For the HVPE-GaN grown on an ammonothermal GaN-seed a very low defect density was ascertained. From the contrasts of the topography threading screw-type dislocations and threading mixed-type dislocations were identified. The structure analyses show that the outstanding structural properties of the ammonothermal GaN-seed are adopted by the HVPE-GaN.

Function-based connection protocol development and verification for secure communication in vehicle environment

The latest advancement of information communication technology has facilitated the development of multifunctional high-performance vehicular communication system and the great strides in user convenience. Still, due to the nature of inter-vehicle communication and that of the communication system between internal and external devices, problems of intruders' attacks arise in transmission sections. Any successful attack on vehicular operating, steering, controlling and imaging systems by intruders would end up in grave safety and privacy issues. In this regard, the need for safe and secure vehicular communication is considered important. In the same vein, the importance of research on hardware security and secure communication protocols is emphasized. This Paper designed a secure vehicular communication protocol using hash locks, random numbers and time-stamps. The proposed protocol was experimentally tested with the formal verification tool Casper/FDR and proved to be secure against diverse attacks from intruders. In brief, the proposed protocol turned out to be safe against deadlock and livelock and to finish without trouble.

Study on the Steady-State Stability Margin of a Weak Section by Using the Online Data of WAMS

To realize the on-line quick analysis of the steady-state stability margin for the weak section of a power grid, a method of dividing the important generator groups according to the impact of the system equivalent impedance on the static stability limits of the section is presented. By using the dynamic information provided by the Wide Area Measurement System (WAMS), the center of inertia (COI) of the section of the two sides system is determined. Then the steady-state stability limits of the transmission section and the static stability margin can be calculated. The algorithm is verified by taking the out-play cross-section of West Inner Mongolia as an example, the results show that the static stability power limit and the steady-state stability margin of the section can be obtained accurately according to the presented algorithm. This algorithm can provide an effective analytical method for the online static stability security analysis of a power system.

Spin Wave Transmission by Spin Impurities in a Quasi-1D Heisenberg Ferromagnetic Tubular Structure

This paper introduces a theoretical study to investigate, at a low temperature, the spin wave propagation and total magnon transmission via atomic substitution sites in a quasi-1D Heisenberg ferromagnetic tubular structure. The model system consists of four ordered ferromagnetic atomic chains, arranged in the space of a parallel manner two to two and containing a finite number of substitution sites, considered as spin impurities. The model is supported on a non-magnetic substrate and considered otherwise free from magnetic interactions with its environment. To describe the dynamics of the tubular structure, we used the theoretical matching procedure. The total transmission and reflection cross sections at the boundary containing the substitution sites are calculated and analyzed as a function of the incident frequency per propagating mode of the perfect quasi-1D tubular structure. The impurity observables are numerically calculated for different cases of softening and hardening to investigate how the local dynamics can respond to changes in the microscopic environment on the perturbed domain. Our results show the interferences between incident spin modes and the localized spin states of the substitution sites. The observe effects are induced by the modification of boundary magnetic exchange values and spin intensity of the impurity sites of the system. The results yield, also, an understanding for the relationship between the coherent magnon transmission and the position of the substitution spin sites in the studied structure.

Synchrotron White-Beam X-Ray Topography Analysis of the Defect Structure of HVPE-GaN Substrates

The defect structure of HVPE-GaN crystals is examined using synchrotron white-beam X-ray topography (SWXRT) and topography results are interpreted and discussed in comparison to reciprocal lattice point broadening from high resolution X-ray diffraction (HRXRD) measurements. Two as-received commercial HVPE-GaN wafers from two different vendors and one HVPE-GaN which was grown on an ammonothermal GaN-seed are investigated in this study. To our knowledge SWXRT large area back-reflection analysis of HVPE-GaN grown on an ammonothermal GaN seed has been performed for the first time. From large-area topography the formation of a cellular defect network is identified for the commercial HVPE-GaN. Large differences in the crystal lattice misorientation deformation (mosaicity) are determined for the different samples by transmission section topography. For the HVPE-GaN grown on an ammonothermal GaN-seed a very low defect density was ascertained. From the contrasts of the topography threading screw-type dislocations and threading mixed-type dislocations were identified. The X-ray topography analysis shows clearly and for the first time that the nature of the defect structure and the low density of ammonothermal GaN seeds can be transferred by HVPE growth of GaN.

분산 제어와 Mid-Span Spectral Inversion이 적용된 광전송 링크에서 반 전송 구획의 잉여 분산이 전체 잉여 분산에 미치는 영향

분산 제어와 Mid-Span Spectral Inversion이 적용된 광전송 링크에서 반 전송 구획의 잉여 분산이 전체 잉여 분산에 미치는 영향

English

This paper presents a device for the blind people that provide navigation and real time monitoring. The key idea behind the development of the device relies on providing navigation using GPS receiver with user required location names announcement and user relatives or a remote operator can provide real time assistance by monitoring the video transmitted by a RF camera. The RF camera at the user side acts as a transmission section continuously transmits video streams to RF receiver, acts as a receiving section. The RF receiver with antenna receives the video streams and displays it on the computer monitor using XGA TV box. The receiving video on the computer also contains the audio of the user. By hearing the audio of the user in the video, user relatives or a remote operator provides immediate assistance by identifying the user current staying locations and surroundings during the emergency conditions such as need of any medical help or in unsafe situations.

Theoretical and Experimental Study of the Modified Pill-Box Window for the 220-GHz Folded Waveguide BWO

The modified pill-box window is designed and manufactured as a power-coupler part of the 220-GHz folded waveguide backward wave oscillator in the Institute of Applied Electronics. Owing to the modified structure, both the fringe area and the end area of the thin dielectric window piece can be metalized, thus the reliability of vacuum seal and strength can be greatly improved compared with its traditional counterpart. An analytical method is developed from the previous equivalent circuit theory of the traditional pill-box window. According to the analytical expressions, the inner parameter of the modified pill-box window is roughly designed. The 3-D computer code is used to verify and further optimize the analytical design. The calculation shows good consistency between the theoretical and the numerical methods. The resonant modes in this oversized window system are also numerically calculated to demonstrate that it is difficult to remove all the modes from the operating frequency range. Fortunately, the error analysis shows that these possible spurious modes are hardly stimulated in the window system with TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode injected, when the misalignment of each transmission section can be limited to the practical mechanical tolerance. For this requirement, an innovative mechanical structure is then proposed to guarantee the precision of the parameters of window system which can nicely restrain the variations caused by the brazing process. By carefully controlling the errors in machining, assembly, and brazing process, the brazed and nonbrazed samples are finally manufactured and tested. The experimental result indirectly demonstrates that the microwave circuit design and the mechanical design is reasonable and reliable, where the reflection ratio is <0.1 between the frequency range of 215–225 GHz.

자동차 보안시스템에서 통신 인증프로토콜의 보안성 검증

자동차산업의 발전과 함께 차량전자통신시스템이 고성능화 되어가고 있으며 사용자 편의 면에서도 상당히 많은 발전을 거듭해가고 있다. 그러나 통신시스템의 특성상 전송구간에서 공격자의 공격에 대한 문제가 제기되고 있으며 안전한 통신에 대한 필요성이 중요시 되고 있다. 자동차의 운행, 제어계통 및 영상장비 등에 공격자의 공격이 성공하게 되면 안전 및 프라이버시에 심각한 문제가 발생하게 된다. 따라서 하드웨어적인 보안 및 보안통신프로토콜에 대한 연구가 중요한 부분으로 이루어지고 있다. 본 논문에서는 안전한 차량 통신프로토콜을 제안하며 공격자의 각종 공격에 안전한 프로토콜을 정형검증도구인 Casper/FDR 도구를 이용하여 실험하였으며 제안 프로토콜이 안전하며 문제없이 종료됨을 확인하였다. Vehicular electronic communication system has continued to develop in favor of high performance and user convenience with the evolution of auto industry. Yet, due to the nature of communication system, concerns over intruder attacks in transmission sections have been raised with a need for safe and secure communication being valued. Any successful intruder attacks on vehicular operation and control systems as well as on visual equipment could result in serious safety and privacy problems. Thus, research has focused on hardware-based security and secure communication protocols. This paper proposed a safe and secure vehicular communication protocol, used the formal verification tool, Casper/FDR to test the security of the proposed protocol against different types of intruder attacks, and verified that the proposed protocol was secure and ended without problems.

Evaluation of health-care providers’ knowledge of childhood tuberculosis in Lima, Peru

Background:As most national tuberculosis programmes (NTPs) focus on adult tuberculosis (TB), NTP providers may not appreciate differences in the pathophysiology and presentation of childhood TB.Objectives:This study aimed to identify strengths and weaknesses in knowledge of childhood TB among the 326 NTP providers in Lima Ciudad and Lima Este—two of the Peruvian capital’s four health districts.Methods:310 providers—103 physicians, 106 nurses, 101 nursing technicians—accepted personal invitations to complete self-administered surveys, which included 14 childhood TB questions grouped into five sections: transmission, symptoms, diagnosis, prevention and treatment. Physicians were asked ten additional questions targeting their NTP diagnostic and management responsibilities.Results:All three groups scored 97–99% on the transmission section and 83–85% on the treatment section; however, no group scored above 66% on any other section. Fewer than 50% of nurses and technicians recognised young children’s high risk of extrapulmonary TB, extrapulmonary TB symptoms or the causes of false negative tuberculin skin tests. Twenty-three per cent of physicians correctly identified gastric aspirate culture sensitivity, and 42% the radiographical findings of pulmonary TB. Less than two-thirds of providers recognised the definition of latent TB infection (LTBI), young children’s high risk of progression from LTBI to disease or indications for isoniazid preventive therapy.Conclusions:Providers at the frontline of Peru’s TB control efforts demonstrated weaknesses in the areas of extrapulmonary disease, diagnosis and prevention. These knowledge gaps are likely to have resulted in delayed or missed diagnoses and lost opportunities for prevention. Educational interventions targeting NTP personnel may improve childhood TB care and outcomes.

Automatic identification of transmission sections based on complex network theory

Taking transmission sections as the monitoring objects of power system security and stability level can largely improve the efficiency of analysis and control in power system operation. However, existing approaches for identifying transmission sections mainly depend on years of experience, which is not suitable for complicated and variable power systems with large scales. Thus, a novel method for automatic identification of transmission sections using complex network theory is proposed. The proposed method presents the fundamental conditions of transmission sections and identifies them from three levels: transmission lines, key transmission links and partition sections. First, based on the small-world characteristics of power grid, the index of transmission betweenness is presented to identify key transmission links from transmission lines. Then clustering algorithm of complex network is used to divide the power grid and to obtain partition sections from the key transmission links. Finally, the combinations of partition sections are selected and ranked as the transmission sections. Numerical results with CEPRI-36 system and a provincial system are provided to demonstrate the effectiveness and adaptability of the proposed method.

Review of Quick Search for Transmission Section

This paper introduces the current research status of quick search for transmission section. Firstly, the definition of transmission section is introduced. Secondly, search algorithm for transmission section is presented. Thirdly, the safety protection measures that can prevent cascading failure are introduced. Finally, outlook on quick search for transmission section is proposed.

Transmission Section Search for Vulnerable Line Based on Power Transfer Distribution Factor

For the purpose of considering characteristics of transmission line in the round, with utilization of related knowledge in complex network, Integrative Electrical Betweenness has been put forward. The proposed index, on one hand, over comes shortcoming of assuming power only transmit along the shortest path existed in previous indexes. On the other hand, ability of transferring power when other lines removal is considered. In order to further facility to grid security control, a novel method is proposed to search key transmission section of vulnerable line. The algorithm only needs simple calculation, there is no large-scale computation. The proposed algorithm has been tested on New England IEEE 39-bus system to validate its efficacy.

A Fast Search Algorithm for Transmission Section Based on K Shortest Paths

A new algorithm based on K shortest paths is presented for quick search of the transmission section, and then the timely electricity network topology is transferred into a directed graph. Using this new algorithm, k shortest paths would be directly searched for; the transmission section influenced greatly by the power flow shift is then obtained quickly. To avoid leaving part of the search because criteria are too small tributary drain election when using a single path to ensure the integrity of the transmission section. Finally CEPRI36 nodes system simulation is analyzed, and the effectiveness of the algorithm is demonstrated.

Research on Generator Tripping Value of Security and Stability Control

In this paper, the problem of the excessive generator tripping value of security and stability control after occurrence of the N-2 fault in the Shentou-Yantong transmission line of Shanxi DaTong Regional grid is studied. And the principle of security and stability control measures based on equal area criterion is analyzed. The reason leading to excessive generator-tripping value of security and stability control after the occurrence of the N-2 fault in Shentou-Yantong region is figured out, and it is that the steady-state stability limit of transmission section decreases and the accelerator power cannot be released. Finally, the results of theoretical analysis are verified by simulations. The simulation results indicate that too large generator-tripping value of security and stability control is mainly caused by decrease of the steady-state stability limit of the transmission section after occurrence of the fault in Datong. The conclusions in the paper have referential significance for the study on similar power concentrated send-out systems.

Development of Control System for MRS Groundwater Exploration Instrument Based on Ethernet

The control system for Magnetic Resonance Sounding (MRS) groundwater exploration instrument was developed on the platform of LabVIEW. This system consists of transmission and reception sections. The former transmits current, controls power and acquires current and the latter controls amplifier, acquires MRS signals. In order to improve efficiency of data transmission, Ethernet based on TCP/IP is used in the system. Furthermore, the system has additional functions of pulse moment setting, equipment detection, data processing into pictures and data storage. Through outdoor experiments, it is found that the average error is less than 2%. The experimental results demonstrate the effectiveness and correctness of the system.