检索结果-南通市图书馆

Science China(Technological Sciences) 2010年第2期53卷 512-518页

作者： YANG QiXin, XU Peng & ZHENG ShangFeng 1 School of Civil Engineering, Southwest Jiaotong University, chengdu 610031, China School of Civil Engineering Southwest Jiaotong University

In this study the computerized tomography (CT) was first used to quantitatively analyze the failure of acrylate spray-applied waterproof membrane in the groundwater environment. The results of the CT tests show that it is feasible to use the CT to quantitatively analyze the failure of the waterproof membrane and the CT method has the advantages of speediness and accuracy that can eliminate the fussy operation process in routine tests. The main conclusions summarized from the study are as follows. First, there are two combined-indexes that can be used to decide the failure of the spray-on waterproof layer: one is that the reduced percentage of the CT number of the spray-on waterproof layer is less than 40.0% and the other is that the variance of the CT number decreases first and then increases. Second, the applicability for the spray-on waterproof layer in the groundwater environment is the SO 24-concentration ≤ 1%, the Cl-concentration ≤ 7.5% and the pH value ≤ 12.0 of the groundwater, respectively.

关键词： spray-on waterproof layer scan CT number failure groundwater environment

STABILITY ROBUSTNESS MEASURES OF LINEAR STATE-SMCE MODELS WITH STRUCTURED PERTURBATIONS

在线全文

学校读者我要写书评

暂无评论

Systems Science and Mathematical Sciences 1998年第1期11卷 32-38页

作者： (Institute of APPlied Mechanics, Southwest Jiaotong University, chengdu 610031, China)

This paper considers the robust stability of state-space models of linear systemssubject to real structured perturbations. The "Zero exclusion principle ", which is basedon the properties of the Kronecker product and the bialternate product, is employed toderive the new robust stability bounds for time-invariant perturbations. Vaious examplesare presented to demonstrate the merit of the method proposed. The examples show thatthe new bounds are easy to compute numerically and can expect an arbitrary degree ofimprovement over the previous ones reported by the Lyapunov stability method and thefrequency domain approach.

关键词： Robust stability linear uncertain systems structured perturbations matrisapproach.

CYCLIC VISCOPLASTIC DESCRIPTION FOR THE MEAN STRAIN EFFECT

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 1995年第2期8卷 111-117页

作者： Yang Xianjie(Southwest Jiaotong University)chengdu,China,610031

ＣＹＣＬＩＣＶＩＳＣＯＰＬＡＳＴＩＣＤＥＳＣＲＩＰＴＩＯＮＦＯＲＴＨＥＭＥＡＮＳＴＲＡＩＮＥＦＦＥＣＴＣＹＣＬＩＣＶＩＳＣＯＰＬＡＳＴＩＣＤＥＳＣＲＩＰＴＩＯＮＦＯＲＴＨＥＭＥＡＮＳＴＲＡＩＮＥＦＦＥＣＴ￥ＹａｎｇＸ... 详细信息

ＣＹＣＬＩＣＶＩＳＣＯＰＬＡＳＴＩＣＤＥＳＣＲＩＰＴＩＯＮＦＯＲＴＨＥＭＥＡＮＳＴＲＡＩＮＥＦＦＥＣＴＣＹＣＬＩＣＶＩＳＣＯＰＬＡＳＴＩＣＤＥＳＣＲＩＰＴＩＯＮＦＯＲＴＨＥＭＥＡＮＳＴＲＡＩＮＥＦＦＥＣＴ￥ＹａｎｇＸｉａｎｊｉｅ（ＳｏｕｔｈｗｅｓｔＪ...

关键词： strain rate effects cyclic viscoplasticity constitutive equations

Centroid-based semi-fragile audio watermarking in hybrid domain

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2010年第3期53卷 619-633页

作者： WANG HongXia & FAN MingQuan School of Information Science and Technology, Southwest Jiaotong University, chengdu 610031, China School of Information Science and Technology Southwest Jiaotong University

Many previous (semi-) fragile audio watermarking schemes adopt binary images as watermarks, which reduce the security of watermarking systems. On the other hand, the content-based or feature-based second generation digital watermarking has limited applicability, and its partial feature points may be damaged by watermarking operations and various common signal processing. To overcome these problems, in this paper, a novel centroid-based semi-fragile audio watermarking scheme in hybrid domain is proposed. The theoretical lower limit of signal to noise ratio (SNR) for objective evaluation of the imperceptibility of watermarked audio signal is deduced, and the watermark embedding capacity and the tamper detection ability are theoretically analyzed. In the proposed scheme, first, the centroid of each audio frame is computed, then Hash function is performed on the obtained centroid to get the watermark, after that, the audio sub-band which carries centroid of audio frame is performed with discrete wavelet transform (DWT) and discrete cosine transform (DCT), and finally the encrypted watermark bits are embedded into the hybrid domain. Theoretical analysis and experimental results show that the proposed scheme is inaudible and applicable to different types of audio signals. Furthermore, its ability of tamper detection and tolerance against common signal processing operations are excellent. Comparing with the existing schemes, the proposed scheme can effectively authenticate the veracity and integrity of audio content, and greatly expand the applicability of the content-based audio watermarking scheme.

关键词： semi-fragile audio watermarking centroid inaudibility tamper detection

Experimental Study on the Uniaxial Cyclic Deformation of 25CDV4.11 Steel

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2005年第1期21卷 5-9页

作者： Guozheng KANG, Qianhua KAN and Juan ZHANGDepartment of Applied Mechanics and Engineering, Southwest Jiaotong University, chengdu 610031, ChinaProf., Ph.D., Dept. of Appl. Mech. and Eng. Southwest Jiaotong Univ. Chengdu 610031 China

The strain cyclic characteristics and ratcheting behavior of 25CDV4.11 steel were studied by the experiments under uniaxial cyclic loading with relatively high cyclic number and at room temperature. The cyclic hardening/softening feature of the material was first observed under the uniaxial strain cycling with various strain amplitudes. Then, the ratcheting behavior of the material was researched in detail, and the effects of stress amplitude and mean stress on the ratcheting were discussed under uniaxial asymmetrical stress cycling. Comparing with the experimental results of SS316L stainless steel, it is concluded that the material exhibits remarkable cyclic softening feature, and then a special ratcheting behavior is caused. Some conclusions useful to establish corresponding constitutive model are obtained.

关键词： Ratcheting Cyclic softening Cyclic plasticity Uniaxial loading

Experimental Study of Tunnel Fire with Natural Ventilation

在线全文

学校读者我要写书评

暂无评论

湖南大学学报（自然科学版） 2009年第S1期36卷 23-25页

作者： YUAN Zhong-yuan,LEI Bo,CHEN Peng-yun(School of Mechanical Engineering,Southwest Jiaotong University,chengdu,Sichuan 610031,China) School of Mechanical Engineering Southwest Jiaotong University Chengdu 610031 China

The 1/15 reduced-scale experiments using Froude scaling were designed to study the effect on the smoke control efficiency for subway tunnel fires with natural ventilation *** propane gas fires with heat release rate 11.48 kW was used,which corresponds to the heat release rate 10 MW in the full-scale *** temperature distributions under the ceiling were measured by K-type thermocouples to investigate smoke movement,and the velocity of smoke in shafts was measured by hot-wire anemometer to obtain the smoke extract amount of ventilation *** results show that the smoke temperature under the ceiling varies with the longitudinal different distance from fire *** results also show that the smoke temperature distributions and the smoke control efficiency in tunnel vary with the space between ventilation shafts and vary with the area and the height of ventilation shaft.

关键词： natural ventilation mode metro tunnel fire reduced-scale experiments froude scaling

Frequency/time hopping sequence sets with optimal partial Hamming correlation properties

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2012年第10期55卷 2207-2215页

作者： NIU XianHua 1,2,PENG DaiYuan 1 & ZHOU ZhengChun 3 1 The Provincial Key Laboratory of Information Coding and Transmission,Institute of Mobile Communications,Southwest Jiaotong University,chengdu 610031,China 2 The School of Mathematics and Computer Engineering,Xihua University,chengdu 610039,China 3 The College of Maths,Southwest Jiaotong University,chengdu 610031,China The Provincial Key Laboratory of Information Coding and Transmission Institute of Mobile Communications Southwest Jiaotong University Chengdu China The School of Mathematics and Computer Engineering Xihua University Chengdu China The College of Maths Southwest Jiaotong University Chengdu China

Frequency hopping/time hopping(FH/TH) sequences have found wide applications in various modern FH/TH spread spectrum communications,such as digital cellular mobile communication,short-range wireless communication,personal communication,and multi-user radar,sonar *** order to evaluate the goodness of FH/TH sequences design,the periodic Hamming correlation function is used as an important ***,the length of correlation window is shorter than the period of the chosen FH/TH sequence,so the study of the partial Hamming correlation of FH/TH sequence is particularly *** this paper,a new class of FH/TH sequence sets with good partial Hamming correlation properties is proposed and *** construction of new FH/TH sequence sets is based upon the generalized m-sequence and generalized Gordon-Mills-Welch sequence over a polynomial residue class *** is shown that new FH/TH sequence sets are optimal with respect to the partial Hamming correlation bound.

关键词： frequency hopping/time hopping(FH/TH) sequence partial Hamming correlation optimal FH/TH sequence set

A new real-time eye tracking based on nonlinear unscented Kalman filter for monitoring driver fatigue

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

控制理论与应用（英文版） 2010年第2期8卷 181-188页

作者： Zutao ZHANG 1 , 2 , Jiashu ZHANG 2 (1.School of Mechanical Engineering, Southwest Jiaotong University, chengdu Sichuan 610031, China 2.Sichuan Key Lab of Signal and Information Processing, Southwest Jiaotong University, chengdu Sichuan 610031, China) School of Mechanical Engineering Southwest Jiaotong University Chengdu Sichuan China Sichuan Key Lab of Signal and Information Processing Southwest Jiaotong University Chengdu Sichuan China

A new scheme for driver fatigue detection is presented, which is based on the nonlinear unscented Kalman filter and eye tracking. Assuming a probability distribution than to approximate an arbitrary nonlinear function or transformation, eye nonlinear tracking can be achieved using an unscented transformation (UT), which adopts a set of deterministic sigma points to match the posterior probability density function of the eye movement. Driver fatigue can be detected using the percentage of eye closure (PERCLOS) framework in a realistic driving condition after the eye nonlinear tracking. This system was tested adequately in realistic driving environments with subjects of different genders, with/without glasses, in day/night driving, being commercial/noncommercial drivers, in continuous driving time, and under different road conditions. The last experimental results show that the proposed method not only improves the robustness for nonlinear eye tracking, but also can provide more accurate estimation than the traditional Kalman filter.

关键词： Eye tracking Unscented Kalman filter (UKF) Fatigue detection PERCLOS

A NONPROPORTIONAL CYCLIC VISCOPLASTIC CONSTITUTIVE MODEL

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 1994年第3期7卷 221-227页

作者： Yang Xianjie Gao Qing Sun Xunfang (Southwest Jiaotong University,chengdu,610031,P.R.China) Southwest Jiaotong University Chengdu 610031 China

A viscoplastic constitutive model is introduced,which takes into account nonproportional cyclic additional hardening and the effects of nonproportional cyclic loading history and inelastic strain amplitude *** the model,a variable q of memory on the inelastic strain amplitude during loading is introduced,a new nonproportionality is defined,a cyclic saturated isotropic deformation resistance parameter Q,is given,and the evolution equations of the isotropic deformation resistance with the memory on the previous loading history are *** present model is applied to the description of the complex cyclic deformation behavior of 1Cr18Ni9Ti stainless steel,and the predictions are in good agreement with the experimental *** shows that the model describes the deformation behavior of nonproportional cyclic loadings and their histories very well.

关键词： viscoplasticity constitutive equations cyclic loading nonproportional loading

Design of a 400 N and 12 mm Mechanical Air Gap High Temperature Superconducting Linear Synchronous Motor

在线全文

学校读者我要写书评

暂无评论

稀有金属材料与工程 2011年第S3期40卷 319-321页

作者： Yen Fei1,2,3, Li Jing1,2,3, Zheng Shijun1,2,3, Jiang Donghui1,2,3, Liu Lu1,2,3, Liu Wei1,2,3, Ma Guangtong1,2,3, Wang Jiasu1,3, Wang Suyu1,3 1 Applied Superconductivity Laboratory, Southwest Jiaotong University, chengdu 610031, China 2 State Key Laboratory of Traction Power, Southwest Jiaotong University, chengdu 610031, China 3 National Laboratory for Rail Transit, chengdu 610031, China SW Jiaotong Univ Appl Superconduct Lab Chengdu 610031 Peoples R China SW Jiaotong Univ State Key Lab Tract Power Chengdu 610031 Peoples R China Natl Lab Rail Transit Chengdu 610031 Peoples R China

The static thrust output on a superconducting coated conductor coil at different excitation and alternating current suspended above a three phase alternating current long-stator comprised of copper coils is presented. Excitation current up to 45 A was applied through the superconducting coil acting as the excitation system of the superconducting linear synchronous motor (SLSM), alternating current up to 9 A was applied to the armature and magnetic air gaps of 10 and 15 mm were investigated for four different cases; coreless, with an iron core or yoke and both a core and yoke. By scaling up and converting the studied superconducting single pancake racetrack coil into a double pancake coil and connecting four of such coils in series, an SLSM prototype capable of generating 400 N of thrust output and 1 kW of power output with a 12 mm mechanical air gap operating at 77 K is proposed.

关键词： high temperature superconductivity linear synchronous motor long stator motor superconducting coil force measurements