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In this paper, we study how to provide optimal performance guarantee in multi-resource scenarios, such as Network Function Virtualization (NFV), where Virtual Network Function (VNF) resource demands of one Service Function Chain (SFC) are elastic and correlated with the end-to-end throughput of SFC. Previous works such as Dominant Resource Fairness (DRF) achieve this goal only if the demands are already...
Insulators are under residual DC voltage after opening of disconnectors. When disconnectors reclose, overvoltage will be superimposed on the pre-existing DC voltage. As a result, insulators in GIS will be under combined voltage of DC and impulse. In this paper, flashover characteristics of insulators in SF6 are studied under combined voltage of DC and lightning impulse. The results show that for non-contaminated...
The basin-type insulator is one of the most important parts in SF6 gas insulated switchgear (GIS). Flashover of basin-type insulators will cause serious harm to the electrical system. The fact that metallic particle attached to the surface cannot be detected in the delivery test under the standard lightning impulse (SLI) will pose potential threat to GIS. This paper studied flashover characteristics...
Excess moisture in GIS will condense on solid insulating materials under certain environmental conditions and cause the reduction of flashover voltage, thus threatening its normal operation. To formulate proper standard of moisture content in GIS, it's necessary to study the influence of moisture on the dielectric strength of insulators. In this paper, the influence of moisture on the flashover voltage...
In order to find out the detection effectiveness of GIS insulation defects when suffering different overvoltages, a coaxial bus line of 220kV with a needle attached to it was established as an experimental sample to simulate the practical condition that there existed a metallic particle on the bus line of real GIS. Research was carried on with the help of 1MV steep-fronted impulse generator. By changing...
Gas-insulated metal-enclosed switchgear (GIS) is an important switching equipment in modern power system. Since GIS equipment has a fully enclosed structure, once failure occurs, it will always be followed by a huge economic loss and an adverse social impact. On-site lightning impulse (LI) test is very important to improve the quality of the GIS equipment since it is particularly sensitive to some...
It is of great significance to detect different defect types of HVDC bushings effectively for the safe operation of power system and the condition maintenance of power transformers. In order to simulate the insulation defects of the main insulation of the HVDC bushings, five samples of the main insulation of the HVDC bushing with a maximum DC voltage of 30kV are fabricated by a vacuum impregnation...
Compared to spherical particles, which are the most prevalent subjects studied by other researchers, free wire-type metallic particles have unique motion phenomena in electric fields under DC voltage, playing an important role in insulation flaw detection of power equipment. However, this is rarely researched sufficiently. Thus, the enclosed experimental chamber and the observation systems are specially...
The Integrated Video Conference System of State Grid hosts many video conference applications. It is an important office assistant system, comprises a massive number of discrete components. In order to meet the growing demands and expectations of customers, stability and reliability of the system need to be further enhanced. In this paper, we study the system architecture, maintenance routine, system...
The fault-tolerance control in scale-free wireless sensor networks against cascading failure is analysed in this paper. Based on the node load redistribution and constant capacity of the scale-free wireless sensor networks, a new load distribution model is proposed under a single random node failure. By the probability generating function method, the relationships between the load and the largest...
In recent years, SF6/N2 was getting used as insulation medium in gas-insulated equipment for replacing pure SF6 which causes greenhouse effect. For the application of SF6/N2 in power equipment such as GIS and GIL, the breakdown characteristics of SF6/N2 in varying electric field non-uniformity under standard lightning impulse were studied in this paper based on an impulse experimental platform. The...
The flashover of insulators is a bottleneck for the development of gas insulated transmission line (GIL). The operation experience of GIL shows that metallic particle plays an important role in flashover of the insulator. An experiment platform was established to study the influence of gas pressure on the flashover characteristics of the post insulator in SF6 under negative DC voltage. The impacts...
Very fast transient overvoltages (VFTOs) generated during the routine operations of disconnector switch in GIS make great threat to the insulation of power equipment such as GIS. So far, the research results of the insulation characteristics of GIS under VFTO have big dispersion and poor comparability for the waveform parameters of VFTO have not been standardized. A generating system of double-exponential...
Solid insulation tended to absorb moisture during the operation and maintenance of oil-immersed transformers, which could be dangerous to the apparatus especially under rated conditions. As had been researched, wet insulation could lead to bubble effect in turn-to-turn insulation when the temperature in transformer increased rapidly. Primarily, this paper investigated the degradation of dielectric...
SF6 is widely used in high-voltage equipment due to its excellent insulation ability. However, when the moisture content in SF6 exceeds a certain value, its insulation could be damaged, threatening the normal operation of high-voltage equipment. Therefore it's of great importance to establish proper control standards on moisture content in SF6. In this paper, the influence of moisture content on flashover...
Network Function Virtualization (NFV) is an emerging technology proposed to improve service provisioning in telecommunication industry. The flexibility of NFV enables network operator to dynamically deploy Virtual Network Functions (VNFs) according to real-time requirements. However, a large amount of VNFs with low utilization may be deployed in network due to dynamic arrival and departure of services...
Applying 3D graphics software UG to create three kinds of typical oil groove structure for wet friction plate model, using T / Grid hybrid mesh for the model grid and finally using Fluent RNG k–ε turbulence model and the moving reference frame for simulation, one can get to know the different flow field of cooling oil in three kinds of typical oil grooves. Comparatively analyze the inner flow fields...
An identification method based on multi-aspect target scattering characteristics when the transmitting and receiving transducer are separated is proposed in this essay. Target strengths of each target at different bistatic angles are calculated, and form a combined vector. Then the first-order and second-order moment features are abstracted. Pool experiment of three targets has been conducted, and...
In conventional single-phase 25kV AC traction power supply system, there are some outstanding power quality problems including three-phase voltage unbalance and large reactive power. Moreover, the neutral section insulators at exits of substations affect the safety and efficiency of the electric trains, especially in high speed railway and heavy haul railway. In this paper, a new traction power supply...
Vision-based vehicle detection has received increasing attention in recent years in the framework of advanced driver assistance systems. However, the variability of vehicle and background poses an enormous challenge. In this paper, an approach used 4-dimensional mapping of RGB colors and integrated with corners and edges features is proposed to detect preceding vehicles in images, addressing the shortage...
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