Buffeting research of suspension steel frame for ±500 kV converter station DC filter

Being a part of a coastal ± 500 kV DC filter converter station, the suspension steel frame is studied in this paper on the field of strong wind induced vibration. In order to analyze the characteristics of the structure, the response of the suspension steel frame under fluctuating wind load is analyzed by FE method. The study is significant on the area of design and maintenance

Uncertainty analysis on process responses of conventional spinning using finite element method

Conventional spinning is a widely used metal forming process to manufacture rotationally axis-symmetric and asymmetric products. Considerable efforts have been made to investigate the forming quality of spun parts using the process in recent years. However, inherent uncertainty properties involved in the spinning process are rarely considered in previous studies. In this paper, an uncertainty analysis and process optimisation procedure have been developed and implemented on conventional spinning with 3D Finite Element Method (FEM). Three process variables are randomized by Gaussian distribution to study the probabilistic characteristics of two process responses. Linear and quadratic approximate representations are constructed by Monte Carlo based Response Surface Method (RSM) with Latin Hypercube Sampling (LHS). The Most Probable Point (MPP) method, which has been widely used to estimate the failure probability in other applications, is further developed in this paper to obtain the probability distribution of the system responses. Following an evaluation of the system responses conducted by the MPP method, a control variable method is used to reduce the variance of spun part wall thickness and total roller force to satisfy the 3σ quality requirement. This uncertainty analysis and process optimisation procedure can be easily implemented in other metal spinning processes. © 2014 Springer-Verlag Berlin Heidelberg

Deformation and fracture of AMC under different heat treatment conditions and its suitability for incremental sheet forming

By evaluating the deformation and fracture mechanisms of a 6092Al alloy metal matrix composite reinforced with 17.5p vol. % SiC particles (6092Al/SiCp), this paper investigates the applicability of using incremental sheet forming (ISF) process to form the 6092Al/SiCp aluminium matrix composite (AMC) under different heat treatment conditions. Tensile tests were carried out at different strain rates to study the microstructure and topography of the 6092Al/SiCp sheet by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The tensile test results and the morphology of the fracture showed that the 6092Al/SiCp to T6 condition has low elongation to fracture (0.08), whilst much improved elongation can be achieved after annealing to O-condition. A series of ISF tests were carried out to form 6092Al/SiCp sheet into a truncated hyperbolic shape with different ISF process parameters. At T6 condition, ISF testing showed unsatisfactory results for the 6092Al/SiCp with a low wall angle (31.2ο) to fracture and a significant amount of springback. After annealing to O-condition, a much increased wall angle was achieved with reduced springback due to the enhanced ductility of the 6092Al/SiCp material. Microstructural and topographic evaluation of the 6092Al/SiCp parts formed by ISF allowed a detailed characterisation of brittle and ductile fractures for different heat treatments. The obtained ISF results and evaluation enabled the recommendation of optimum ISF operational windows for 6092Al/SiCp materials

Evaluation of deformation stability and fracture mechanism in incremental sheet forming

Incremental sheet forming (ISF) is a flexible process for rapid manufacturing of complex sheet metal parts. An advantage of ISF is the improved formability than traditional sheet forming processes such as stamping. A number of fundamental studies have been conducted to investigate the enhanced ISF formability considering the effects such as bending under tension and through thickness shear. To further understand the ISF deformation mechanism and formability enhancement, this work presents a new analytical model which is focused on investigating the deformation stability and its effect on the metal sheet fracture. Based on this new model, the critical strain of deformation instability is obtained. Furthermore, influences of the work-hardening effect and bending effect on the deformation stability are investigated. To validate the analytical model, the fracture occurrence of two aluminum grades, AA1100 and AA5052, are investigated by using ISF experiment. Based on the analytical and experimental investigation, this study has concluded that bending plays a major role on ISF deformation stability. In addition, the ISF fracture depends on both deformation stability and the sheet material's ductility

Poboljšana adaptivna pretvorba ostataka prilikom H.264/AVC video kodiranja bez gubitka kvalitete

The H.264/AVC was designed mainly for lossy video coding, the lossless coding of H.264 use bypass mode for DCT and quantization. Although sample-by-sample DPCM improves performance of coding, the benefit is limited in intra. In this paper, a new adaptive transform is proposed based on the character of 4x block residual coefficient\u27s distribution, which can be used both in intra and inter coding. The greatest strength of the proposed transform is the decorrelation without inflation versus dynamic range of input matrix. Due to the random distribution of residual coefficients, a specific transform is hard to play a positive impact on them. Therefore, several transforms of different directions will be implemented simultaneously, and the most efficient one will be determined by a proposed mechanism. Then, by means of statistic method, a new scan order is designed for CAVLC entropy encoder, cooperating with corresponding transform. The simulation results show that based on the fast algorithm of proposed method, the bit saving achieves about 7.41% bit saving in intra coding and 10.47% in inter, compared with H.264-LS.H.264/AVC je napravljen prvenstveno za kodiranje videa uz gubitak kvalitete, dok kodiranje H.264 bez gubitka kvalitete koristi zaobilazni mod za DCT i kvantizaciju. Iako uzorak-po-uzorak (DPCM) kvantizacija poboljšava performanse kodiranja, dobitak je ograničen. U ovom radu predlaže se nova adaptivna transformacija koja se zasniva na znakovima od 4x4 blokova distribucije ostataka koeficijenata, koja može koristiti i unutarnje i među kodiranje. Najveća snaga predložene transformacije je u nekoreliranosti bez inflacije protiv dinamičke veličine ulazne matrice. Radi slučajne distribucije ostataka koeficijenata, teško je postići da određena transformacija ima pozitivan učinak na njih. Iz tog razloga istovremeno je implementirano nekoliko transformacija različitih pristupa, te je korištenjem predloženog mehanizma odabrana najefikasnija. Zatim je, korištenjem statističke metode, dizajniran novi poredak snimanja za CAVLC entropijski enkoder, koji surađuje s odgovarajućom transformacijom. Rezultati simulacija pokazuju da korištenjem brzog algoritma predložene metode dolazi do smanjenja korištenih bitova od 7.41% kod među kodiranja i 10.47% prilikom unutarnjeg kodiranja u usporedbi s H.264-LS

Spatio-temporal analysis of driving factors of water resources consumption in China

Abstract(#br)China is the largest consumer of water resources in the world, the total consumption of water resources is still increasing year by year. What are the main reasons for rising water resource consumption? This paper constructs China’s spatio-temporal LMDI (the Logarithmic Mean Divisia Index) model to decompose water resources consumption into twelve driving factors with panel data from 2000 to 2015 and explores the main factors driving the rising water resource consumption. The results are summarized as following: (1) The intensity effect is the most important driving factor decreasing water resources consumption; (2) The loss of farmers reduces the water resources consumption in the agricultural sector, and the increase of urban population drives the rising water resource consumption in the residential sector; (3) The effect of industrial structure is different depending on regions; (4) In the agricultural sector, the driving factors have their own characteristics in each region