Volume 34,Issue 2,2011 Table of Contents

1 The mid-infrared spectra characteristic of the transformer oil-paper insulation in thermal ageing process

LIAO Rui-jin , ZHOU Xuan , YANG Li-jun , XIANG Bin

2011, 34(2):1-6. DOI: 10.11835/j.issn.1000-582X.2011.02.001

[Abstract](3364) [HTML](0) [PDF 6.03 M](2222)

Abstract:
Transformer oil and insulation paper are the research objects, accelerated aging experiments in laboratory are performed. The infrared spectrums of samples of different aging time are obtained by the FT-RI apparatus. The absorption intensity of insulation paper’s stretching vibration of O-H at the wave number of 3 346 cm-1 is weaken with the ageing time, so it can be the characteristic quantity of ageing and it can also be the basis for the on-line monitoring of insulation paper in practical transformers. Transformer oil has C=C and C=O group absorption peak at the wave number of 3006 and 1740 cm-1，and the intensity of the absorption peak became stronger with the aging time. The mid-infrared spectra characteristic of the transformer oil-paper is analyzed. The process and mechanism of transformer oil-paper insulation ageing is explored from perspective of microscopic functional groups.

2 Influential factors analysis on photoacoustic signal of photoacoustic spectroscopy monitoring trace gases

CHEN Wei-gen , LIU Bing-jie , HU Jin-xing , ZHOU Heng-yi , LI Jian

2011, 34(2):7-13. DOI: 10.11835/j.issn.1000-582X.2011.02.002

[Abstract](2112) [HTML](0) [PDF 7.55 M](1617)

Abstract:
Photoacoustic spectroscopy (PAS) is a highly sensitive gas analyzing method without the shortcoming of gas consumption, which can be used in transformer oil trace gases dissolved in on line monitoring. The photoacoustic signal is detected with a microphone, which is the only feature in gas concentration analysis. A portable and tunable experimental setup has been developed based on the photoacoustic spectroscopy fundamental. Through the photoacoustic signal stimulate mechanism analysis, this paper thoroughly discusses the influences of gas pressure, temperature, laser power, gas concentration, background gas, chopped frequency and the resonant frequency drift on the gas photoacoustic signal. The theoretical and experimental results supply reference and technical support for further improvements in oil gas photoacoustic spectroscopy of on-line monitoring system.

3 The optical isolation method of suppressing electromagnetic interference of automotive ignition system

WANG Quan-di , LIU Qing-sheng , JIA Jin , ZHENG Ya-li , LIU Qing-song

2011, 34(2):14-18. DOI: 10.11835/j.issn.1000-582X.2011.02.003

[Abstract](2304) [HTML](0) [PDF 5.14 M](2278)

Abstract:
Electromagnetic radiation, which is caused by the engine ignition system, is the most powerful electromagnetic interference (EMI) source in the vehicles, as well as the main reason of most electronic control unit (ECU) malfunction. In order to reduce interference from ignition noise on ECU, we use optical isolation technology to isolate electrical connections between the interference source and the control circuit. The formation mechanism of the ignition system EMI is analyzed. The possibility of suppressing ignition system EMI with optical isolation technology is discussed. Then, as a result we design an experimental platform of suppressing ignition system EMI. The experimental results show that the effect of suppressing ignition noise, in 20~100 MHz frequency band, is obvious after applying optical isolation circuit. It can address the issue of automotive EMC.

4 A telemetring technique on deformation of large tower

YANG Li-sheng , CAO Hai-lin , YANG Shi-zhong , WANG Tao

2011, 34(2):19-25. DOI: 10.11835/j.issn.1000-582X.2011.02.004

[Abstract](2377) [HTML](0) [PDF 7.63 M](1422)

Abstract:
This paper describes a telemetring technique on deformation of large Electrical Power Equipment. We install n radio beacons apart Δ Hi each other at large structure. The carriers of n beacons are same but modulated by different orthogonal PN codes. So the telemetring equipment can divide the carriers of n beacons. The phase detectors measure the phase difference between the ith carrier and ( i -1)th carrier Δ θi(i=2, 3…n) . The corresponding deformations are Δ Li =Δ θi/360×λ(i=2, 3…n) .The deformation curve can be deduced from Δ Li and Δ Hi(i=2, 3…n) . The method to eliminate the interference between the modulated carriers is presented .The simulation test is conducted and the result of the simulation proves the effectiveness of the proposed technique.

5 Spatio-temporal channel assignment in multi-radio wireless mesh networks

HU Zhi-yuan , GUO Jian-ding , WANG Jing , SU Jia-yong

2011, 34(2):26-31. DOI: 10.11835/j.issn.1000-582X.2011.02.005

[Abstract](2806) [HTML](0) [PDF 6.35 M](1492)

Abstract:
A method of spatio-temporal channel assignment based on graph decomposition was proposed to solve the ripple effect and link failure problem in multi-radio wireless mesh networks. Network topology was decomposed into subgraphs in several time slots to extend channel assignment from spatial domain to time domain. Then, graph coloring algorithm was used to optimize the channel assignment on the basis of the subgraph in each time slot. Each subgraph obtained channel resource dynamically according to the network constraints to improve the channel assignment efficiency. Simulation results show that, compared to static channel assignment scheme, the impact of negative factors, such as the ripple effect and link failure caused by channel switching, are effectively confined with this strategy. The network throughput is increased at least by 30% while satisfying the constraints on the number of radios and the number of network channels.

6 Adaptive fractional differential and its application to image texture enhancement

WANG Cheng-liang , LAN Li-bin , ZHOU Shang-bo

2011, 34(2):32-37. DOI: 10.11835/j.issn.1000-582X.2011.02.006

[Abstract](3373) [HTML](0) [PDF 6.21 M](1678)

Abstract:
Optimal fractional differential order can be only specified manually by experiments. In order to significantly save time of manually seeking optimal fractional differential order, a novel approach is studied and proposed, which is based on window size, G-L formula, image gradient and visual property to automatically generate fractional differential order. The fractional differential operator masks are designed and realized by employing this order. The evaluation parameters of image texture, such as information entropy and average gradient were used for quantitative analysis and experimental verification. The results show that, for any grey image, this method can obtain a successive enhancement result, which approximates the results of optimal fractional differential order and more satisfies human visual sense. It is an effective approach to enhance image texture.

7 Design of converter of DC-AC type contactless power transfer system

WANG Zhi-hui , SUN Yue , DAI Xin , TANG Chun-sen

2011, 34(2):38-43. DOI: 10.11835/j.issn.1000-582X.2011.02.007

[Abstract](2806) [HTML](0) [PDF 5.40 M](1407)

Abstract:
A new type of circuit topology for DC-AC type contactless power transfer(CPT) system is proposed, and the asymmetric DC-AC convert is used to imply the new topology. The topology simplifies the circuit and control of DC-AC type CPT system, reduces the power loss of power conversion of secondary circuit, and improves the overall efficiency and power density of the system. This paper presents the topology of the converter and investigated its control strategy. A model of the system has been derived, with which the system is simulated and studied. The measured experimental results have verified the theoretical and simulation results.

8 Design of simulation blocks for variable voltage or variable frequency power source

SU Yu-gang , LIU Yao-zhong , XIA Chen-yang

2011, 34(2):44-51. DOI: 10.11835/j.issn.1000-582X.2011.02.008

[Abstract](1974) [HTML](0) [PDF 7.32 M](1927)

Abstract:
Based on Matlab/Simulink platform, a method of designing the variable DC voltage power source, variable AC voltage power source and variable AC voltage and variable frequency power source block is proposed. The functions of variable voltage or variable frequency power sources are realized by combining controlled voltage source with self-defined piecewise linear function. Variable DC voltage power source and AC voltage power source are built by using the existing models in Simulink. The S-Function description, which signal parameters are arranged in the matrix, was presented in variable AC voltage and variable frequency power source block. These blocks are first encapsulated as Simulink blocks, then embedded into Matlab/Simulink platform to extend the Simulink warehouse. The simulation has demonstrated the feasibility of our method. The novel designed variable voltage or variable frequency power source block can introduce great convenience for analyzing dynamic behavior and performance of power electronic system. The designing idea has universal use to extend the warehouse of the other simulation software of circuits.

9 Police-based encryption for privacy protection of trust negotiation

YU Ling , CHEN Shu-yu

2011, 34(2):52-57. DOI: 10.11835/j.issn.1000-582X.2011.02.009

[Abstract](2106) [HTML](0) [PDF 4.86 M](1177)

Abstract:
Privacy protection technologies of automated trust negotiation have witnessed great development, among which hidden credentials is an admittedly more satisfactory one. However, for hidden credentials, there exists fatal weakness of blindly decryption, which results decryption execution costly. To solve the problem, using bilinear pairings over elliptic curves, a policy-based encryption for privacy protection is proposed. Under the assumption of BDH problem, the scheme is proven to be IND-Pol-CCA safety in the random prediction model. Compared with hidden credentials and other encryption solutions based on policy, this scheme is more efficient, secure and of shorter length of cipher text.

10 The spatial distribution estimation of Interference temperature based on kriging method in cognitive radio

FENG Wen-jiang , LI Jun

2011, 34(2):58-63. DOI: 10.11835/j.issn.1000-582X.2011.02.010

[Abstract](1773) [HTML](0) [PDF 5.05 M](1160)

Abstract:
In order to resolve the problems of the traditional interference temperature estimation methods, such as unclear spatial characteristics, inaccurate estimation of spatial distribution, and the insufficient use of spectrum resources, this paper proposes an estimation method which utilizes the interference temperature sample values obtained by wireless sensors distribute in space to estimate the interference temperature in the total area. This method makes use of the geo-statistical interpolation method of Kriging to calculate the interference temperature data and obtain the 3-dimensional distribution of the interference temperature in the area. Kriging interpolation method is based on the variogram and structure analysis theory, makes optimal estimation of the variables in area. Simulation results demonstrate that the proposed method can estimate the spatial distribution of interference temperature in the interested area more accurately and the spatial spectrum utilization is improved.

11 Novel channel estimation algorithm for OFDM/TDM over fast fading channels

WU Yu-cheng , WU Dan , ZHOU Qiang

2011, 34(2):64-68. DOI: 10.11835/j.issn.1000-582X.2011.02.011

[Abstract](2872) [HTML](0) [PDF 4.25 M](1325)

Abstract:
For the shortage of tracking ability against fast fading channel of the existing pilot structures and channel estimation algorithms in OFDM combined with time division multiplexing (OFDM/TDM) system, an improved channel estimation algorithm is proposed. The channel transfer functions are obtained by estimating the channel properties with two adjacent time domain multiplexing (TDM) pilot sequences, while the channel state information of the OFDM/TDM symbols is obtained with interpolation Combined with frequency domain equalization based on minimum mean square error (MMSE-FDE), the proposed algorithm can significantly compensate the path loss over fast fading channels. Simulation results show that, compared with the existing channel estimation algorithms, the proposed algorithm can achieve better performance, which is not only capable of dealing with slow fading channels, but also has a better tracking ability against fast fading channels with the same data transmission efficiency.

12 A power distributed computing system model based on services-oriented architecture

WANG Cheng-liang , LI Ren , WANG Zhu-ding

2011, 34(2):69-73. DOI: 10.11835/j.issn.1000-582X.2011.02.012

[Abstract](2584) [HTML](0) [PDF 4.33 M](1730)

Abstract:
Process communication based power distributed computing model satisfies the demand on real time monitoring and analysis for the economical operation of power grid based on power distributed computation methods, but there are some problems on complexity in common basic functions development and lack of system extendibility. An extendable services-oriented power distributed computation system model is designed and implemented. Software design patterns are applied to design low coupling and extendable system framework. Windows Communication Foundation (WCF) technology is used to implement the services-oriented distributed data communication functions. Windows Workflow Foundation (WWF) technology is used to design the business logic of power distributed computation visually. Data integration functions are implemented by combining the ADO.NET technology. The services-oriented system architecture enhances the integration ability and extendibility. The use of WCF and WWF technology reduces the complexity of the system development.

13 Coordinated torque control strategy for driving-mode-switch of strong hybrid electric vehicle

YANG Yang , YANG Wen-hui , QIN Da-tong , DUAN Zhi-hui

2011, 34(2):74-81. DOI: 10.11835/j.issn.1000-582X.2011.02.013

[Abstract](2578) [HTML](0) [PDF 24.76 M](3309)

Abstract:
For a new type of strongly hybridized system, the vehicle ride performance is used as the study goal, a coordinated control strategy is put forward to suppress the torque surge after the analysis of the parameters changes of engine, motor, clutch and transmission during the driving-mode-switch process. The strongly hybridized vehicle simulation model is developed based on the coordinated control strategy. The typical drive mode switching process performance simulation and analysis are performed. The results show that introducing the coordinated control strategy reduces the torque surge during the driving-mode-switch process and improves the vehicle drivability.

14 Precise measurement system of small workpiece base on video

GUO Yong-cai , GAO Chao , YANG Yang , ZHU Hong-jun

2011, 34(2):82-85. DOI: 10.11835/j.issn.1000-582X.2011.02.014

[Abstract](2689) [HTML](0) [PDF 3.70 M](1549)

Abstract:
There are some weaknesses for traditional microscope measurement, including small scope field, complex operation and subjective errors. To avoid these issues, a measurement system combining video and microscope is made. With the magnification of microscope and video, the accuracy of grating micrometer and the real-time notification of chamfer location, this system achieves high precise measurement. By displaying with two monitors, the computer can collect and display other measurement data while the chamfer is measured, which makes full use of the display resolution and enhances the efficiency of instruments. The method is valid for measuring size of special work-pieces.

15 Optimal model and algorithm for flexible job-shop scheduling problem based on demand time window

ZENG Qiang , YANG Yu , WANG Xiao-lei , XING Qing-song

2011, 34(2):86-94. DOI: 10.11835/j.issn.1000-582X.2011.02.015

[Abstract](2313) [HTML](0) [PDF 11.42 M](1881)

Abstract:
Aiming at the scheduling problem for jit delivery under the pulling type production, an optimal method for flexible job-shop scheduling problem (FJSP) based on demand time window is proposed. According to the demand time window of every workpiece, an optimal model for FJSP is constructed to maximize the average membership degree based on the completion time for every workpiece.Then, a tabu search algorithm based on multi-stage hybrid mutation is proposed and designed.To improve the convergence of the algorithm, inverse order mutation and gene segment swap mutation are used to find a good original solution, upon which gene swap mutation is used to find the optimal solution. The effectiveness of the proposed method is validated by applying to a multi-type and small-batch production manufacturing workshop.

16 The model of information exchange and sharing for CAD/CAPP using STEP and XML schema

CHEN Shou-qiang , CAI Chang-tao

2011, 34(2):95-100. DOI: 10.11835/j.issn.1000-582X.2011.02.016

[Abstract](2506) [HTML](0) [PDF 7.23 M](1340)

Abstract:
To solve the problem of product data exchange and sharing among heterogeneous systems, the key technologies, including manufacturing information sharing, file conversion from STEP AP203/AP214 to AP224 with the conversion ware of STEP neutral files, are discussed.Using STEP standard as information output of CAD systems, the AP203/AP214 file output from CAD systems is transformed to AP224 file with STEP neutral file, while CAPP systems obtained geometry and manufacturing process information of the parts with AP224 neutral files.By translating the STEP files into corresponding XML neutral files according to the transformation criterions constituted by STEP AP28, XML schema library is setup.Upon this, product data exchange and sharing of manufacturing information can be achieved.

17 Research and development of a parallel piezoelectric 4-axis force/torque sensor

LIU Jun , QIN Lan , LIU Jing-cheng , LI Min , XUE Lian

2011, 34(2):101-107. DOI: 10.11835/j.issn.1000-582X.2011.02.017

[Abstract](3148) [HTML](0) [PDF 8.12 M](3307)

Abstract:
This paper proposed a novel parallel piezoelectric four-axis force/torque sensor based on the bottleneck contradictions of elastic style multi-axis wrist force sensor, It introduces the sensor's structure and operating principle and discussed the selection and spatial layout of piezoelectric quartz wafer group.Then it derives the mathematic model of the sensor. The finite element model of the sensor is established, and the prototype of the sensor is manufactured. Finally, it obtains the input and output curve, voltage sensitivity, charge sensitivity and the coupling interference.The results indicate that the sensor has advantages of simple and rational structure, correct mathematic model, nice manufacturability, good linearity, good rigidity, and natural frequency greater than 30 kHz, less than 3% of the interference error without decoupling matrix.These can meet the requirements of sensor design.

18 Mechanism and implementation of directional quantum-behaved particle swarm optimization in OC-SVM

YAO Fu-guang , ZHONG Xian-xin

2011, 34(2):108-112. DOI: 10.11835/j.issn.1000-582X.2011.02.018

[Abstract](2097) [HTML](0) [PDF 4.99 M](1262)

Abstract:
This paper uses the training of OC-SVM to analyze the mechanism of the Quantum-behaved particle swarm and develops a method of training OC-SVM based on the directional- QDPSO .The new position of the directional particle is calculated based on the current global best point(gBest), which identified the optimized direction conforms to Zoutendijk fastest decline method principle.In the initialization, the position of one particle is initialized according to SMO, which makes its position nearer to the global optimum solution. The boundary points of subjected plane are concerned as the initialized position of other particles, so as to make the searching area wider.The experiment result shows that the convergence and the generalization of D-QDPSO is good, the misrecognition of D-QDPSO is 0.12% lower than that of SMO, and the operating speed is 2 times faster than that of LPSO.

19 Bearing capacity of solid waste ground reinforced by stone column

GAO Hai , SHI Jian-yong , WANG Rui

2011, 34(2):113-119. DOI: 10.11835/j.issn.1000-582X.2011.02.019

[Abstract](2064) [HTML](0) [PDF 7.28 M](1434)

Abstract:
Based on presented tests of improvement of solid waste ground by stone column, the failure mode of lateral expansion of column body can be found. It is assumed that solid waste surrounding column is in Rankin's positive limit situation caused by lateral expansion of column body, self weight solid waste and column is neglected, the calculation theory of limit bearing capacity of stone column can be extended on equilibrium of solid waste and column. The limit bear capacity of stone column can be calculated on parameters by complete tests and reference data. The heavy dynamic penetration tests were finished in stone column and the characteristic value of bearing capacity can be recommended on blow count. It is shown that bearing capacities of calculation and field test are close.

20 Test on engineering properties of unsaturated undisturbed loess Q2

ZHONG Zu-liang , ZHANG Jian , LIU Xinrong , FANG Jinbing , ZHOU Yang

2011, 34(2):120-124. DOI: 10.11835/j.issn.1000-582X.2011.02.020

[Abstract](2326) [HTML](0) [PDF 5.66 M](1285)

Abstract:
A series of triaxial shear tests with controlled constant confining pressure are conducted to study the failure modes, effects of deformation, strength and yield properties of unsaturated undisturbed loess Q2, with improved SJ-1A triaxial shear equipment. The test results show that the failure mode of unsaturated undisturbed loess Q2 is shear failure with the rupture angle between 55 and 61 degree; Shear dilatancy is shown under low confining pressure, and shear shrinkage is shown under high confining pressure; The stress-strain curves of undisturbed loess Q2 will change from perfectly plastic to weak strain softening as the confining pressure increases; A effective method is suggested to identify the field stress of undisturbed loess Q2 under triaxial shear condition with the curves of - q/p ; when the confining pressure increases, the deviatoric yield stress qy has a logarithmic relationship with net mean yield stress py .

21 Beam element end release by extra degree of freedom method

WANG Zhong-quan , ZHANG Qi-lin , KANG Lan

2011, 34(2):125-129. DOI: 10.11835/j.issn.1000-582X.2011.02.021

[Abstract](2696) [HTML](0) [PDF 5.94 M](1872)

Abstract:
This paper develops a new method of extra degree of freedom (extra DOF) for the beam element with end release. Based on the strain matrix with extra DOFs, it derives the stiffness transformation matrix of released element, which can be applied to situations along global coordinate system or element local coordinate system. The effects of end release processing method for beams with large displacement are analyzed, and the results compared with those from other existing methods show that the extra DOF processing method has higher performance and accuracy.

22 Simplified numerical modeling and simulation of compositelaminated plates by the variational asymptotic method

ZHONG Yi-feng , YU Wen-bin

2011, 34(2):130-135. DOI: 10.11835/j.issn.1000-582X.2011.02.022

[Abstract](2740) [HTML](0) [PDF 5.41 M](1576)

Abstract:
This paper develops a simplified model for composite laminated plates by the variational asymptotic method (VAM) in order to efficiently analyze the nonlinear, one-way couples problem. It deduced the 3D energy expressions based on the decomposition of rotation tensor (DRT). The 3D laminated plate model is decomposed into a 2D plate analysis and a non-linear 1D analysis along the normal direction. The approximate energy after dimensionality reduction was deduced and converted to a form of reissner model. The 3D field recovery relations are provided to obtain accurate stress distribution through the thickness direction. The cylindrical bending example of 4-layer composite plate shows that the 3D stress fields recovered by this theory have better accuracy than those by the classic laminated theory (CLT), which indicates the validity of this model.

23 Rock classification method for tunnel boring machine

LU Jin , WU Ji-min , LIAO Xiao-fan

2011, 34(2):136-141. DOI: 10.11835/j.issn.1000-582X.2011.02.023

[Abstract](1900) [HTML](0) [PDF 6.03 M](1281)

Abstract:
In order to study the geological factors which impact penetrating rate of tunnel boring machine (TBM), this paper uses three-dimensional discrete element model 3DEC to build simulated models on rock fragment by TBM cutter. It analyzes the influence of different geological conditions on TBM penetrating rate and classified the surrounding rock in west route of south-to-north transfer project according to the drill ability of TBM in surrounding rock. The results show that the penetrating rate of TBM is closely related to the mechanical properties of rock and joint conditions in rock mass. In certain extent, TBM penetrating rate will be increased with the decrease of rock strength or closely distributed joints. TBM penetrating rate will be decreased with the increase of rock strength or rarely distributed joint. Another result is that the surrounding rock by TBM penetrating can be divided into three classes based on the drill ability of TBM in surrounding rock, which can guide the TBM penetrating.

24 Study on dynamic assessment model and its application to tunnel health

LI Ming , CHEN Hong-kai

2011, 34(2):142-148. DOI: 10.11835/j.issn.1000-582X.2011.02.024

[Abstract](2750) [HTML](0) [PDF 5.85 M](1514)

Abstract:
This paper uses normalized elements in the sample database to avoid the influence of index type and dimension. Basing on the index system and grade standard of tunnel health safety assessment, it puts forward the relative difference function of variable fuzzy set by the method of set pair analysis and confirming reasonable the relative membership function of the related health indexes in every level and its level standard interval, and develops the assessment model of tunnel health after confirming the relative indexes right by multiplication scale method. Once confirming the eigenvalue of health levels, some samples are given to verify the scientificity and rationality of the method in, the results show that the calculation process is visual, simple, strong currency, result is reasonable and precision is high. The model can be used for various system assessment problems and it’s propitious to promote the more use of variable fuzzy sets in the field of civil engineering.

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