作者机构：
[Li, Linsheng; Zeng, Li; Liu, Linghui] Chongqing Univ, Educ Minist China, ICT Res Ctr, Key Lab Optoelect Technol & Syst, Chongqing 400044, Peoples R China.;[Zeng, Li] Chongqing Univ, Coll Math & Stat, Chongqing 400044, Peoples R China.;[Li, Linsheng; Zhu, Hongmei; Qiu, Changjun] Univ S China, Coll Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Zeng, Li] C;Chongqing Univ, Coll Math & Stat, Chongqing 400044, Peoples R China.
关键词：
3D image segmentation;Active contour;C-V model;Image processing;Robust statistics
摘要：
The segmentation of 3D images has important applications in the non-destructive examination of industrial computed tomography (CT) and has been widely studied. When a C-V model is used to segment the image, closed and accurate object contours can be obtained. The C-V model is suitable for image segmentation and extended easily to a 3D application. However, industrial CT images may have artifacts or noise, which may make active contours stop at undesired boundaries. In order to overcome these difficulties, the 3D C-V model is improved by the robust statistics method. In this improved model, the intensity of the image in the 3D C-V model is replaced with robust statistics, which is the weighted combination of the inter-quartile range, mean absolute deviation and intensity median in the local region of the image. Inter-quartile range and mean absolute deviation in the local region are introduced to sharpen object boundaries, and the intensity median in the local region reduces image noise. The comparison experiments demonstrate the position accuracy of the contours and robustness to noise of the improved model.
摘要：
Intensity inhomogeneity may cause considerable difficulties in segmentation of CT image. In order to overcome the difficulties caused by intensity inhomogeneity, the region-scalable fitting (RSF) model was put forward. RSF model draws upon intensity information in local regions with a controllable scale. But only using intensity information may lead to slow convergence rate and poor denoise ability. Combining the method of robust statistics, RSF model is improved in this paper. In the improved model, the intensity in RSF model is replaced with local robust statistics which is the weighted combination of inter-quartile range, mean absolute deviation and intensity median in local region. Inter-quartile range and mean absolute deviation in local region are introduced to sharpen object boundaries, and intensity median in local region is introduced to reduce image noise. The contrast experiments between RSF model and the improved model are provided, which demonstrate the fast convergence rate and robustness to noise of the improved model.
关键词：
coupled heat and moisture transfer;transient moisture content;multi-layer porous building envelope
摘要：
A new facility was presented which can expediently and cheaply measure the transient moisture content profile in multi-layer porous building envelope. Then, a common multi-layer porous building envelope was provided, which was constructed by cement mortar-red brick-cement plaster. With this kind of building envelope installed in the south wall, a well-controlled air-conditioning room was set up in Changsha, which is one of typical zones of hot and humid climate in China. And experiments were carried out to investigate the temperature and moisture distribution in multi-layer building envelope in summer, both in sunny day and rainy day. The results show that, the temperature and humidity at the interface between the brick and cement mortar are seriously affected by the changes of outdoor temperature and humidity, and the relative humidity at this interface keeps more than 80% for a long-term, which can easily trigger the growth of mould. The temperature and humidity at the interface between the brick and cement plaster change a little, and they are affected by the changes of indoor temperature and humidity. The temperature and humidity at the interface of the wall whose interior surface is affixed with a foam plastic wallpaper are generally higher than those of the wall without wallpaper. The heat transfer and moisture transfer in the envelope are coupled strongly.
作者机构：
[Zhu, H. M.; Ringer, S. P.; Liu, Z. W.; Sha, G.] Univ Sydney, ARC Ctr Excellence Design Light Met, Australian Ctr Microscopy & Microanal, Sydney, NSW 2006, Australia.;[Luo, C. P.; Zhu, H. M.; Liu, J. W.] S China Univ Technol, Sch Mat Sci & Engn, Guangzhou 510640, Guangdong, Peoples R China.;[Zhu, H. M.] Univ S China, Sch Mech Engn, Hengyang 421001, Peoples R China.
关键词：
Atomic force microscopy (AFM);Dislocation;GaN;X-ray diffraction (XRD)
摘要：
The effect of the coalescence of islands on threading dislocations (TDs) in GaN films (300 nm thick) grown on non-annealed and annealed sapphire substrates has been studied. Atomic force microscopy measurements show that the a-type TD density first decreases and then increases during the coalescence process, while the densities of (a + c)- and c-type TDs decrease as coalescence proceeds. X-ray diffraction data indicate that the lattice tilt of GaN films is greatly reduced by coalescence while the change in twist depends on the degree of coalescence. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
摘要：
Nanolithography on SrRuO3 (SRO) thin film surfaces has been performed by a scanning tunneling microscope under ambient conditions. The depth of etched lines increases with increasing bias voltage but it does not change significantly by increasing the tunneling current. The dependence of line-width on bias voltage from experimental data is in agreement with theoretical calculation based on field-induced evaporation mechanism. Moreover, a three-square nanostructure was successfully created, showing the capability of fabricating nanodevices in SRO thin films.
期刊：
IEEE Transactions on Industrial Informatics,2007年3(4):302-311 ISSN：1551-3203
通讯作者：
Chen, Z.(zzchen801@163.com)
作者机构：
[Chen, Zhongze; Shan, Changhong] College of Electric and Electronic Engineering, University of South China, Hunan Province 421001, China;[Zhu, Huiling] College of Mechanical Engineering, University of South China, Hunan Province 421001, China
通讯机构：
[Chen, Z.] C;College of Electric and Electronic Engineering, University of South China, China
关键词：
Adaptive control;fuzzy sliding mode control;non-affine nonlinear system
作者机构：
[Xie, HB] Northeastern Univ, State Key Lab Rolling & Automat, Shenyang 110004, Liaoning, Peoples R China.;Nanhua Univ, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;Panzhihua Iron & Steel Grp Co, Hot Strip Mill, Panzhihua 617062, Sichuan, Peoples R China.
通讯机构：
[Xie, HB] N;Northeastern Univ, State Key Lab Rolling & Automat, Shenyang 110004, Liaoning, Peoples R China.
关键词：
hot rolled strip;laminar cooling;control system;model parameter optimization
摘要：
The structure of laminar cooling control system for hot rolling was introduced and the control mode, cooling strategy, segment tracking and model recalculation were analyzed. The parameters of air/water cooling models were optimized by regressing the data gathering in situ, and satisfactory effect was obtained. The coiling temperature can be controlled within ± 15 °C.
期刊：
2005 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND BIOMIMETICS,2006年:427-+
通讯作者：
Li Guoping
作者机构：
[Li Guoping] Ningbo Univ, Fac Engn, Ningbo, Zhejiang, Peoples R China.;[Zhang Chunliang] Nanhua Univ, Coll Mech Engn, Hengyang, Hunan, Peoples R China.
通讯机构：
[Li Guoping] N;Ningbo Univ, Fac Engn, Ningbo, Zhejiang, Peoples R China.
关键词：
active vibration control;bionic mechanics;isolation platform;LQG
摘要：
Based on the bionics mechanics, a vibration isolation platform is developed. This system uses air springs and rubber layer as passive vibration isolation elements and giant magnetostrictive actuators as active vibration isolation elements. Actuators and air springs are arranged in parallel. The air springs and the rubber layer of the passive system are synthesized so as to minimize the root-mean-square values of amplitude of the isolation platform and the discrete time LQG controller based on a state space model is employed for controlling actuators. Simulation studies show that the developed active vibration control system has good isolation performance against the floor disturbance over wide frequency area. For random or white noise excitation, the amplitude of isolation platform is reduced to approximately 15% by the active control system.
期刊：
Zeitschrift fuer Metallkunde/Materials Research and Advanced Techniques,2003年94(9):1006-1011 ISSN：0044-3093
通讯作者：
Rao, KP
作者机构：
City Univ Hong Kong, Dept Mfg Engn & Engn Management, Kowloon, Hong Kong, Peoples R China.;Cent S Univ, Coll Mat Sci & Engn, Changsha 410083, Peoples R China.;Nanhua Univ, Coll Mech Engn, Hengyang, Peoples R China.;[Rao, KP] City Univ Hong Kong, Dept Mfg Engn & Engn Management, Tat Chee Ave, Kowloon, Hong Kong, Peoples R China.
通讯机构：
[Rao, KP] C;City Univ Hong Kong, Dept Mfg Engn & Engn Management, Tat Chee Ave, Kowloon, Hong Kong, Peoples R China.
摘要：
The flow behavior and hot deformation mechanisms of Ti-6Al-4V in both βand (α+ β) phase regions have been studied by compression tests in the temperature range 750-1100°C and strain rate range 0.05-15 s<sup>-1</sup>. The flow curves displayed discontinuous yielding at temperatures above 850°C and high strain rates, typically 5 and 15 s<sup>-1</sup>. Flow oscillations were also observed under such conditions. The relative discontinuous flow stress drop increased with increasing temperature in the (α+ β) phase region and reached a steady state in the βphase region. The discontinuous yielding is attributed to the sudden increase in the mobile dislocation density occurring due to the activation of βgrain boundary sources during hot deformation. The apparent activation energy estimated using the standard kinetic analysis is about 246 kJ/mol in the βregion and 621 kJ/mol in the (α+ β) region while the strain rate sensitivity values are 0.34 and 0.18, respectively. The mechanism in the βregion has been suggested to involve grain boundary sliding and dynamic recovery of the βphase while in the (α+ β) region a transient mechanism, involving dynamic recovery followed by post deformation recrystallization, has been proposed.
期刊：
International Journal of Mechanical Sciences,2002年44(12):2415-2425 ISSN：0020-7403
通讯作者：
Rao, KP
作者机构：
City Univ Hong Kong, Dept Mfg Engn & Engn Management, Kowloon, Hong Kong, Peoples R China.;Cent S Univ, Dept Mat Sci & Engn, Changsha 410083, Peoples R China.;Nehua Univ, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Rao, KP] City Univ Hong Kong, Dept Mfg Engn & Engn Management, 83 Tat Chee Ave, Kowloon, Hong Kong, Peoples R China.
通讯机构：
[Rao, KP] C;City Univ Hong Kong, Dept Mfg Engn & Engn Management, 83 Tat Chee Ave, Kowloon, Hong Kong, Peoples R China.
摘要：
Hot extrusion of Ti–6Al–4V alloy has been studied using finite element simulation and the results are compared with those obtained experimentally. First, the constitutive behavior of the material and friction at the extrusion temperatures are established based on the results obtained through cylindrical and ring compression tests, respectively. While the flow stress below β transus temperature is expressed as a strain-dependent function, it is taken as strain-independent one at higher temperatures. The distribution of strain, temperature and effective stress has been simulated under different design and processing conditions. Simulation results show that heat generation due to deformation is significant (as much as 160°C) in the hot extrusion of Ti alloys, and it mainly occurs at the beginning of the extrusion process. This leads to reduction in flow stress which, in turn, leads to enlarged deformation zone. A fair agreement has been found between the experimental results and those obtained through simulations.
作者机构：
Cent S Univ, Dept Mat Sci & Engn, Changsha 410083, Peoples R China.;Nanhua Univ, Dept Mech Engn, Hengyang 421001, Peoples R China.;City Univ Hong Kong, Dept Mfg Engn & Engn Management, Hong Kong, Hong Kong, Peoples R China.;[Li, LX; Yang, LB; Peng, DS] Department of Materials Science and Engineering, Central South University, Changsha 410083, PR China;[Lou, Y] Department of Mechanical Engineering, Nanhua University, Hengyang 421001, PR China
摘要：
Samples of Ti-3Al-5V-5Mo alloy were compressed in both beta and alpha + beta phase region on a Gleeble 1500 Simulator. Compression tests were carried out in the temperature range of 700-1000 degreesC and strain rate range of 0.05-15 s(-1). Experimental results show that the flow stress of Ti-3Al-5V-5Mo alloy decreases with the increase of temperature and the decrease of strain rate. At high strain rate, typically 5 and 15 s(-1), discontinuous yielding followed by flow oscillations was observed in both beta phase region and alpha+beta phase region; at low strain rate, the flows display single peak stress. The flow stress at a strain of 0.2 was analyzed with a stand constitutive equation. Activation energy parameters were obtained, and they are 133.46 kJ/mol for the beta phase region and 661.90 kJ/mol for the alpha + beta phase region. Microstructures of the compressed specimens in water-quenched conditions were critically observed. High temperature deformation mechanisms have been elucidated. In the beta phase region, the operative deformation mechanisms are dynamic recovery at high strain rates and grain boundary sliding at low strain rates. In alpha + beta phase region, the alpha phase undergoes dynamically recrystallization at both high and low stain rates. (C) 2002 Elsevier Science Ltd. All rights reserved.
