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Analysis of World Experience in Creating Parallel Computing Systems Designed to Effectively Solve DIS-tasks
Issue:
Volume 7, Issue 5, October 2019
Pages:
101-106
Received:
22 August 2019
Accepted:
23 September 2019
Published:
9 October 2019
Abstract: Author describes world experience in creating parallel computing systems by example Cray XE6 and network chip Gemini, designed to effectively solve Data intensive tasks (DIS-tasks). Most often, in modern supercomputers (SC), architecture options with shared (shared) memory are used to provide effective solutions to problems of high capacitive complexity, including those that contain mostly irregular work with memory. It is possible to provide support for a programming model with shared (shared) memory in various ways using hardware, as well as using virtualization software. Different options for implementing a shared memory programming model may vary in functionality and timing of memory accesses. The problem of the “memory wall” is that if arithmetic-logical operations take several processor cycles, then operations directly with the memory take several hundred cycles. If the memory is formed from the memories of computing nodes connected by a communication network, then the execution time of such a call includes the time of operation with the network to transfer addresses and data. This already increases the memory access time to several thousand cycles. The problem is that such delays in accessing data cause idle functional units of the processor - they cannot perform arithmetic and logical operations on data, because they simply do not exist due to the large delays in performing operations with memory.
Abstract: Author describes world experience in creating parallel computing systems by example Cray XE6 and network chip Gemini, designed to effectively solve Data intensive tasks (DIS-tasks). Most often, in modern supercomputers (SC), architecture options with shared (shared) memory are used to provide effective solutions to problems of high capacitive compl...
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Science Innovation Review: Developers of Supercomputers in Russia
Issue:
Volume 7, Issue 5, October 2019
Pages:
107-112
Received:
18 August 2019
Accepted:
23 September 2019
Published:
14 October 2019
Abstract: Author describes developers of supercomputers in Russia. The situation of a significant predominance of the field of science and education in the use of supercomputers in Russia was created artificially. Author believes that it will gradually improve in the natural process of state development. Due to the fact that the limit of miniaturization of the elemental base on the basis of silicon complementary metal-oxide-semiconductor (CMOS) technologies is approaching, i.e. the end of Moore’s law is approaching (in the region of 2024, currently 22nm, the expected limit is 5 nm in 2020), in foreign countries, parallel to exaflops projects, work is underway on the promising element-design base of the Post-Moore’s era. New application areas may require the creation of cluster supercomputers that differ from most modern ones oriented to high-performance computing, as well as supercomputers that differ from cluster ones, i.e. on a special element base and other special solutions, both in hardware and in software. This, in fact, is happening now in the United States and China. Author shows examples of the development in the world and in Russia of new applied areas for the use of supercomputer resources and these resources themselves. A complete solution to the protection problem is the development of supercomputers with hardware-based security levels for programs and data.
Abstract: Author describes developers of supercomputers in Russia. The situation of a significant predominance of the field of science and education in the use of supercomputers in Russia was created artificially. Author believes that it will gradually improve in the natural process of state development. Due to the fact that the limit of miniaturization of t...
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Arrival Time Difference Estimation of Ultrasonic Signals from Partial Discharge in Electric Power Equipments
Jinxi Hu,
Wenhong Liu,
Haotian Zhang,
Hang Liu,
Keni Xu,
Mianmian Wang
Issue:
Volume 7, Issue 5, October 2019
Pages:
113-119
Received:
12 October 2019
Published:
8 November 2019
Abstract: Partial discharge of power equipment is one of the common faults in power systems. How to quickly and accurately determine the location of partial discharge is a problem that needs to be solved in practice. The signal arrival time difference estimation technique in signal processing is one of the effective methods to solve this problem. When the power equipment is partially discharged, an ultrasonic signal is generated. Therefore, the local discharge can be positioned according to the ultrasonic signal, however, the traditional signal arrival time difference estimation methods are not ideal for the actual low signal-to-noise ratio and narrow-band ultrasonic signals. In this paper, an improved correlation coefficient waveform comparison time difference estimation algorithm based on complete ensemble empirical mode decomposition with adaptive noise（CEEMDAN）, threshold denoising is proposed, referred to as CEEMDAN-TDE. Firstly, according to the characteristics of the actual ultrasonic signals, the double-exponential decay oscillation model is used to model the partial discharge ultrasonic signals, and Gaussian white noises are added as the interference signals. secondly, the CEEMDAN threshold denoising is used to improve the signal-to-noise ratio of the partial discharge signals; thirdly, the cross-correlation coefficient is calculated, then the arrival time difference can be obtained by comparing the waveforms of the correlation coefficients, and the partial discharge location information is known. The computer simulations of the CEEMDAN-TDE method, and the generalized correlation method, LMS method, and correlation coefficient waveform comparison method estimation are performed. Experimental results show that the estimating performance in arrival time difference of proposed method, CEEMDAN-TDE, is better than the other three methods’ under low SNR and narrowband. The CEEMDAN-TDE method has the hopeful more application in practice.
Abstract: Partial discharge of power equipment is one of the common faults in power systems. How to quickly and accurately determine the location of partial discharge is a problem that needs to be solved in practice. The signal arrival time difference estimation technique in signal processing is one of the effective methods to solve this problem. When the po...
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A Method to Improve the Performance of Active Noise Control System Based on Time Delay Estimation
Haotian Zhang,
Wenhong Liu,
Jinxi Hu,
Keni Xu,
Mianmian Wang,
Hang Liu
Issue:
Volume 7, Issue 5, October 2019
Pages:
120-125
Received:
13 October 2019
Published:
8 November 2019
Abstract: Noise control is a research topic that has been widely concerned for in recent years. When a noise space has a certain volume and/or with complex channel, the method of active noise control (ANC) can be used to reduce or eliminate noise interference. The main channel delay in the active noise control system has an important impact on the performance of the ANC system, however, the traditional method, such as filtered-x least mean square algorithm (FxLMS), lacks the estimation of the main channel delay. This results that the system output cannot be accurately synchronized. Especially in the case of time-varying delay, the effect is less desirable. In this paper, the correlation time delay estimation is combined with FxLMS. A method to improve the performance of active noise control system (CTDE-FxLMS) is proposed based on time delay estimation. In CTDE-FxLMS method, the correlation time delay estimation is used to calculate the main channel delay, and the frequency response of the main channel is calculated by FxLMS. CTDE-FxLMS method improves the synchronization accuracy between the system output and the original noise in the time domain and the frequency domain. The computer simulation results show that the CTDE-FxLMS method has better noise reduction effect than the FxLMS method both the conditions of fixed delay and time-varying delay.
Abstract: Noise control is a research topic that has been widely concerned for in recent years. When a noise space has a certain volume and/or with complex channel, the method of active noise control (ANC) can be used to reduce or eliminate noise interference. The main channel delay in the active noise control system has an important impact on the performanc...
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Simulation Research on On-line Multi-parameter Monitoring for Long Distance Three-phase Power Cable
Bo Zhu,
Xinlao Wei,
Hongyan Nie
Issue:
Volume 7, Issue 5, October 2019
Pages:
126-133
Received:
15 October 2019
Published:
18 November 2019
Abstract: Long distance three-phase power cable has the characteristics of the metal sheath cross-bonded and voltage drop and ground potential difference at both ends, which brings confusion to on-line insulation monitoring of long distance power cable. One parameter monitoring cable insulation will effect by voltage drop, load current change, frequency fluctuation and other factor. A method based on dielectric loss factor and resistive current to monitor cable insulation simultaneously has been put forward. The method named as a multi-parameter on-line cable insulation monitoring method. The method installs current transformers and voltage transformers on both side of three-phase cable and uses a high precision timing function of the GPS receiving module at both ends of the testing equipment respectively which can receives the pulse per second from the GPS satellite as time reference can realize the signal synchronous sampling. The principle and formula of the method are given. The metal sheath cross-bonded equivalent circuit of long distance three-phase cable is established by using MATLAB software and does dynamic simulation on the method. The results show that the method is not effect on load current, voltage drop and frequency fluctuation. The two parameters increase obviously when the cable operating temperature exceeds 80°C. The insulation condition of three-phase cable can be judged by the change of dielectric loss factor and resistive current under different insulation fault. The method was proved to be correctness and feasibility in the paper.
Abstract: Long distance three-phase power cable has the characteristics of the metal sheath cross-bonded and voltage drop and ground potential difference at both ends, which brings confusion to on-line insulation monitoring of long distance power cable. One parameter monitoring cable insulation will effect by voltage drop, load current change, frequency fluc...
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