Volume 34,Issue 12,2011 Table of Contents

1 Error analysis of worm grinding wheel precise dressing by diamond roller with straight profile

LIU Feng lin , CHEN Jiu , XU Xiao gang , HE Bing

2011, 34(12):1-8. DOI: 10.11835/j.issn.1000-582X.2011.12.001

[Abstract](1708) [HTML](0) [PDF 8.84 M](1924)

Abstract:
In worm grinding wheel dressing with diamond roller, using straight line instead of theoretical curve of roller will result in dressing error. Method of the precise dressing is studied, while the mathematical model is presented. Theoretical curve of diamond roller is calculated based on the space meshing theory and helicoid equation of worm grinding wheel. The fitting error between the theoretical curve and approximate straight line which is obtained by the theoretical curve is calculated. The dressing error on normal section of worm grinding wheel is analyzed. The case study of a kind of worm grinding wheel with single head shows that the dressing error increases with diameter decreasing of worm grinding wheel and diamond roller, while the variation of diamond roller’s diameter makes little contribution. The validity of worm grinding wheel dressing using straight line diamond roller is proved, and the algorithm can be used as guidance in practice.

2 Effects of time-varying friction coefficient on hypoid gear dynamics

FENG Zhi heng , WANG Shi long , LEI Song , XIAO Hong

2011, 34(12):9-15. DOI: 10.11835/j.issn.1000-582X.2011.12.002

[Abstract](3835) [HTML](0) [PDF 8.90 M](1610)

Abstract:
This paper develops a generalized 3-dimensional 14-DOF dynamic model for hypoid gear which considers the time-varying friction coefficient and lubrication situation. We propose a mixed elastohydrodynamic lubrication(EHL) friction model of hypoid gear tooth contact to reflect the realistic lubricant situation in gear transmission system consisted of full film contact and asperity contact. Under the mixed lubrication condition, the effects of time-varying friction coefficient on gear dynamic is analyzed. The load sharing coefficient is used to calculate the instantaneous friction coefficient at each contact point along the contact path. Friction coefficient model based on mixed elastohydrodynamic lubrication(Mixed EHL) is incorporated into the dynamic model to predict the dynamic mesh force and transmission error with constant and time-varying friction coefficient. The simulation results under a wide range of speed and load show that the time-varying friction coefficient has a marginal effect on the dynamic response.

3 Kinematic and dynamic analysis and simulation on parallel kinematics machine tool

ZHANG Yi , MU Si hui , CHEN Huai jun

2011, 34(12):16-22. DOI: 10.11835/j.issn.1000-582X.2011.12.003

[Abstract](1568) [HTML](0) [PDF 9.22 M](1053)

Abstract:
The parallel kinematics machine tool is based on the space of mechanism. It can achieve space complex motion, meet requirements of processing of multi-degree freedom, and can process complex parts. Because the design process of a parallel kinematics machine tool is quite complicated, there are limitations of the traditional design methods using experience and static researches. It is necessary to explore the related design theories and study the dynamic characteristics of the parallel kinematics machine tool. This study takes a 4-XPXUYYUX parallel kinematics machine tool as an example, develops the mathematical model of kinematics analysis by the coefficient method. The dynamic model is solved using Lagrange equation, which can provide the basis for other theoretical analysis. We develop a simulation model of parallel kinematics machine tool by the virtual prototype software-ADAMS, and analyze the dynamic of parallel kinematics machine tool. The dynamic characteristics of parallel kinematics machine tool are acquired. The system design of parallel kinematics machine tool is improved and optimized.

4 A new measurement method for mass property parameters

WANG Qiu xiao , WANG Ying

2011, 34(12):23-28. DOI: 10.11835/j.issn.1000-582X.2011.12.004

[Abstract](1918) [HTML](0) [PDF 5.70 M](1131)

Abstract:
Mass property parameters (mass, center of mass, moment of inertia) are important technology parameters of aircraft. The traditional mass and center of mass measurement uses centroid units, and the moment of inertia measurement torsion units, which can only get results in installing direction. Because of the structural reasons, there is a need to get all high accurate physical parameters in clamping once. To solve this problem, this study merges centroid units and torsion units into one composite unit, installs a table which can tilt and rotation to measure the moment of inertia in different conditions. The moment of inertia and product of inertia relative to three axis are calculated by the method of coordinate transformation. Measurement theory of mass, center of mass and mass moment of inertia are described, the main reason of causing measurement errors is discussed, and the measurement accuracy affected by tilt error is analyzed.

5 Stiffness optimization of vehicle engine magneto-rheological fluids mounts

CHEN Shi wei , JIAN Kai lin , LI Rui , CHEN Wei min , LIAO Chang rong

2011, 34(12):29-34. DOI: 10.11835/j.issn.1000-582X.2011.12.005

[Abstract](1825) [HTML](0) [PDF 6.89 M](1049)

Abstract:
As important tool for engine semi-automatic isolation system, the magneto-rheological fluids (MRC) can’t achieve tunable stiffness but damping. Therefore, the MRC’s initial stiffness affects the performance of isolation system. To obtain the better isolation effect of MRC in wide frequency, it is necessary to optimize the initial stiffness. As motor unbalanced force and isolation damping are not considered in traditional mount optimization, the feature of semi-automatic control can not be reflected. For a four-cylinder four-cycle in-line diesel engine, a new method which is suitable for stiffness optimization on vehicle engine isolation is presented by using Genetic Algorithm. The optimal isolation system has small absolute force transmissibility in abroad frequency range and small vibration intensity with impact load by using the new method.

6 Discussion on values criterion of strength parameters of weak intercalations

TANG Liang qin , LIU Dong yan , NIE De xin

2011, 34(12):35-41. DOI: 10.11835/j.issn.1000-582X.2011.12.006

[Abstract](1809) [HTML](0) [PDF 7.28 M](999)

Abstract:
The engineering properties of weak intercalations are not only related to the environmental conditions, such as ground stress, ground water, etc., but also to their genesis, granularity composition and mineral composition. Under the same genesis, grain composition and material composition, the relationship between shear strength and water content, properties index (W/Wp), dry density is analyzed by experimental study, and the related equations are established. The results reveal that shear strength increases with the decrease of water content and properties index and the increase of dry density. Therefore, to select strength parameters of weak intercalation in the specific engineering, the factors, such as water content, grain composition, clay mineral composition, and ground stress, should be taken into account. In addition, shortcomings of the strength parameters of weak intercalation that only relies on the quantify index of granularity composition in Design Specification for concrete gravity dams is discussed.

7 Chemical effect of NO on oxidation of CH4

WANG Ying , ZHENG Zhao lei , HE Zu wei , ZHANG Qing feng , WANG Feng

2011, 34(12):42-47. DOI: 10.11835/j.issn.1000-582X.2011.12.007

[Abstract](1939) [HTML](0) [PDF 8.25 M](1028)

Abstract:
A new chemical kinetic mechanism model of NO-CH4 interaction is adopted to simulate the reaction process of CH4 in the plug flow reactor (PRF) and HCCI engine based on the experimental verification. The initial NO mole concentration and reaction temperature are changed and the effect of NO on CH4 oxidation is analyzed. The results show that: NO mainly reacts with alkylperoxy ROO·produced in CH4 oxidative reaction, and alkylperoxy ROO · is transformed into alkoxy radicals RO ·. NO accelerates the oxidation of CH4 at low concentration. With the concentration of NO rising, its performance of speeding up fuel oxidation is inhibited. At low temperature, NO promotes oxidation of CH4. But at high temperature, due to low concentration of alkylperoxy ROO ·, NO almost loses its effects. The effect of NO on ignition delay of HCCI combustion is closely related to its concentration. The ignition delay reduces when NO is at low concentration, and the trend reducing the ignition delay slows down at high concentration. These results are mainly based on competition between R126 and R150.

8 Analysis of embedded gas detection system based on nano-porphyrin arrays

LUO Xiao gang , BAI Xing hong , HOU Chang jun , HUO Dan qun , FA Huan bao , YANG Mei

2011, 34(12):48-53. DOI: 10.11835/j.issn.1000-582X.2011.12.008

[Abstract](1681) [HTML](0) [PDF 6.75 M](1208)

Abstract:
In view of the necessity of gas detection in environment, an embedded gas detection system is designed based on the basic principles of chromatography change of chemical reaction between nano-porphyrin arrays and micro-gas, which takes ARM9 S3C2440A as the core and nano-porphyrin array as the sensors. The overall program, the circuit organization and control software of the main function module such as spectrum signal acquisition, processing and monitoring are presented. With energy conservation differential equation, the control model of temperature and flow rate in the sample chamber is established, which can precisely control the detection conditions of chemical sensors. Some typical trace gases such as ammonia, enanthaldehyde, cyclohexane and hexanal are tested by the system, and the results show that the system can achieve rapid and accurate detection of trace volatile gas.

9 Application of dynamic time warping algorithm to partial discharge pattern recognition

WANG Ke . , YANG Li jun , LIAO Rui jin , DENG Xiao pin , ZHOU Tian chun

2011, 34(12):54-60. DOI: 10.11835/j.issn.1000-582X.2011.12.009

[Abstract](1768) [HTML](0) [PDF 6.95 M](1066)

Abstract:
This study uses the data sequences of apparent charge versus applied voltage （ΔQ-U) in the process of stepping-up/down the voltage as the characteristic features of partial discharge (PD). Based on Dynamic time warping (DTW) algorithm, a method is introduced to realize PD pattern recognition for insulation defect models. In the training process of DTW classifier, the train and test samples are processed by vector quantization (VQ). Moreover, the original vectors are substituted by the codeword to realize data reduction, and the DTW reference templates of various PD types are constructed by the corresponding train samples. In the testing process, the average DTW distances between test samples and each reference templates are calculated based on the accumulated distances. Recognition results are obtained by the recognition rule of nearest neighbor. The new algorithm is also supported by Fast Match (FM) technique to speed up the DTW matching process. The recognition results from five PD sources and 200 samples demonstrate the high classification rates and easy expansion of the proposed DTW algorithm. FM algorithm can save 56 percent computational time and improve the classification rates.

10 A high precision detecting method for fundamental using BP neural network

FU Zhi hong , WANG Hao na , CAO Min , WANG Yong , ZANG Huai qing

2011, 34(12):61-66. DOI: 10.11835/j.issn.1000-582X.2011.12.010

[Abstract](1528) [HTML](0) [PDF 5.98 M](984)

Abstract:
High precision detecting on grid fundamental wave is the basis of energy measurement, power quality assessment and power system automation. This paper presents a high precision detecting method for frequency and amplitude of grid fundamental based on BP neural network. The results show that the intersection of symmetry two points which are between the both sides of signal’s zeros-crossing has monotone relation with frequency, but no linear relation. The intersection is independent with amplitude. Accordingly, we set the mapping of the intersection and the frequency with the BP neural network, and then propose the optimal selection method of symmetry points. These simulation results show that the precisions of frequency and amplitude are so high to 10-4 and 10-5, which are much higher than FFT and Hanning window algorithms. These influences of random noise and harmonic on this method are very small, so it has strong anti-interference.

11 Reliability evaluation algorithm for complex electrical distribution networks using the storage structure of adjacency multilist

CAO Kan , XIE Kai gui , HU Bo , LI Chun yan

2011, 34(12):67-71. DOI: 10.11835/j.issn.1000-582X.2011.12.011

[Abstract](1653) [HTML](0) [PDF 4.42 M](1197)

Abstract:
A section algorithm of reliability evaluation for complex medium voltage Electrical Distribution Networks (EDNs) using adjacency multilist (AM) is proposed. The constructing method for AM is introduced. The AM can be used to store the structure data of EDNs and to solve the problem of space & time complexity. A new power flow algorithm of backward / forward sweep is proposed and a fast algorithm of forming sections in distribution network is put forward. The proposed algorithm makes a perfect combination of the power flow algorithm and the section algorithm of reliability evaluation, which makes efforts to decrease the work of programming and saves the computing time. Applying the proposed algorithm in RBTS-BUS6 system and actual EDNs, the reliability assessment results show that the algorithm has an advantage of saving time and possesses efficiency in engineering practicality.

12 Purification of the shaft centerline orbit with partial differential equation

YIN Ai jun , SUN Li ping , WANG Jian

2011, 34(12):72-77. DOI: 10.11835/j.issn.1000-582X.2011.12.012

[Abstract](2035) [HTML](0) [PDF 6.72 M](1687)

Abstract:
The shaft centerline orbit contains abundant information about fault symptoms, but the measured orbit is often confused by the interference of noise. Based on partial differential equation (PDE), this paper proposes a method for purification of the shaft centerline orbit to overcome the shortcomings of the traditional method. We analyze the principle of filtering based on PDE，PDE filter parameter design and its numerical process. Its correlativity is discussed with the traditional filter and realized the purification of the shaft centerline orbit. Experiment results show that the method is a flexible method of denoise, can effectively eliminate the noise disturbing , also avoid signal distortions after denoise, and at the same time keep the property of signal.

13 Digital modulation mode recognition based on multi-classclassification of support vector machine

ZHANG Hui min , CHAI Yi

2011, 34(12):78-81. DOI: 10.11835/j.issn.1000-582X.2011.12.013

[Abstract](1950) [HTML](0) [PDF 3.58 M](1007)

Abstract:
To solve the overfitting, underfitting and local minimum existing in neural networks, a digital modulation mode recognition method based on support vector machine (SVM) is proposed. Seven characteristic parameters are extracted from instantaneous amplitude, instantaneous phase, instantaneous frequency, frequency spectrum, and changes in characteristics of the envelope to train support vector machine. Compared with the existing algorithms, using binary tree theory to design multi-class classifier has the features of simple, high-speed, high-precision. The simulation results indicate that the scheme can achieve 97% recognition accuracy when the signal to noise ratio (SNR) is above 15 dB with the AWGN channel.

14 First-order load with pulse-width modulation

CHENG Sen lin , YE Zhao hong , GUO Shi gang , XUE Fang zheng

2011, 34(12):82-87. DOI: 10.11835/j.issn.1000-582X.2011.12.014

[Abstract](1416) [HTML](0) [PDF 6.81 M](1075)

Abstract:
For the limitation of the dynamic and time-varying characteristics of the load simulator, a novel design method for the first-order electrical load is presented. By adjusting the turn-on time of switches, the first-order load with the parameters in a certain range can be simulated. The simulation degree of the electrical load might be judged with the area percent of function distance in the load response. For the simulations on three loads with cut-off frequencies as 20，50，80 Hz, the PWM period is 1 ms. The duty cycles are 9.9%,39.4% and 69.1%. The simulation deviations are 1.48%,3.92% and 3.57%. The results show that the first-order electrical load designed with this method can simulate any first-order load with the parameters in a certain range .

15 A novel keyframe extraction method based ondynamic time-domain detection windows

TANG Chao wei , WANG Heng , TANG Hui , ZHAO Zhen zhen , ZHOU Xu

2011, 34(12):88-95. DOI: 10.11835/j.issn.1000-582X.2011.12.015

[Abstract](3412) [HTML](0) [PDF 8.10 M](1618)

Abstract:
Real-time keyframe extraction is significant for the on-line video retrieval and recognition system. It will lead to low speed for keyframe extraction by analyzing the frames one by one on the basis of shots detection. A novel keyframes extraction method based on dynamic time-domain detection windows is presented. The video frame-sequence is divided into video units with different lengths. The frames at the edges of the window and the sampled frames inside the window are analyzed to judge the changes of the unit content. Meanwhile, a hybrid growth mode of windows and slow detection mechanism are proposed to ensure the quality and speed of the keyframe extraction. The extracted keyframes are clustered to obtain the best keyframe. The experiments show that the proposed method has a good comprehensive performance for different kinds of videos.

16 Dynamical niche sets-based cooperativeevolutionary algorithm for job shop scheduling

LUO Shu qiang , ZHAO Peng , ZHANG Gen bao

2011, 34(12):96-101. DOI: 10.11835/j.issn.1000-582X.2011.12.016

[Abstract](1598) [HTML](0) [PDF 6.19 M](967)

Abstract:
Job shop scheduling is an important part of manufacturing process. Pre-mature, local optimal solution or low convergence rate of Genetic Algorithm may come across in solving scheduling problem in multi-Job shop. To avoid those unhealthy tendencies, this paper introduced the Dynamical Niche Sets-based Cooperative Evolutionary Algorithm model.In the Algorithm, Process-based chromosome encoding method was used; the crossover operator and mutation operator were designed to adjust operation sequences and choose process routes. The cooperative scheduling problem in multi-Job shop was solved using dynamical niche sets technology and multi-population cooperative evolution method. The Experiment result shows the proposed method has good advantages.

17 Microarray data classifier with dimensionality reductionproximal support vector machines

WANG Li peng , YUAN Zhan ting , ZHOU Zhi fang

2011, 34(12):102-108. DOI: 10.11835/j.issn.1000-582X.2011.12.017

[Abstract](1477) [HTML](0) [PDF 5.55 M](1232)

Abstract:
DNA microarray technologies have changed the foreground of biological medicine, while the generated plentiful data is the key problem for the application of microarrays．Microarray data have the characteristics of large quantity, low sample size and high gene dimensionality. A microarray data classifier with dimensionality reduction proximal support vector machines (DRPSVM). A dimensionality reduction quadratic programming algorithm is used in DRPSVM, which shows faster training speed and smaller memory requirements than traditional PSVM does. Using CAMDA2000, colon 1 dataset and colon 2 dataset as the experimental datasets, the classification performance of DRPSVM is compared with those of BP, Nearest, RBF and SVM. DRSVM shows stable classification performance, existing one and only optimal solution and fast training which is suitable for DNA microarray data classification applications.

18 Research and implementation on WNXD database storage strategy

LIU He hua

2011, 34(12):109-114. DOI: 10.11835/j.issn.1000-582X.2011.12.018

[Abstract](1542) [HTML](0) [PDF 9.14 M](1236)

Abstract:
For the drawbacks of NativeXML, such as low data storage performance, low efficiency of querying and updating, a new kind of semi-structured information storage model, named WNXD, is proposed. The dynamic invert-sorting technique and data imaging mechanism are introduced to combine the record and the page storage mode, three structured indexes are established to achieve structural and dynamic growth with different ways. A practical storage mode is created to provide a comprehensive access strategy from global to local, and from elements, attributes to values, which guarantees effective and complete data storage, especially for the data with different types. The query number decreases I/O and the system performace is improved.

19 Rate control using the rate-distortion properties of the foreground and background regions

LI Ming , CHANG Yi lin , YANG Fu zheng , WAN Shuai

2011, 34(12):115-120. DOI: 10.11835/j.issn.1000-582X.2011.12.019

[Abstract](3445) [HTML](0) [PDF 6.94 M](1573)

Abstract:
In order to improve the rate control performance of video encoder, video frames are segmented into two regions according to the video content, i.e. the foreground region containing the main moving objects and the background region containing the relatively static scene. The rate-distortion properties of the two regions are analyzed. Based on the analyses, a novel region-based macroblock layer rate control method for H.264/AVC is proposed. For the bit allocation process, more target bits can be assigned to the important macroblocks by employing an adaptive factor determined by the region information. Then, the quantization parameter (QP) is computed by using the quadratic model with different parameters related to the two regions. The computed QP is further adjusted to suppress the coding quality fluctuation between the two regions, as well as the quality fluctuation among the consecutive macroblocks. Finally, the rate control parameters are updated after coding the current macroblock. Experimental results demonstrate the mismatches between the actual coding bit-rates and the target bit-rates are reduced, while the coding performance of the encoder and the subjective visual quality of the reconstructed video are improved.

20 Multi-scale optical flow estimation of the video based on gradient optimization

HU Xue gang , LI Wen yu

2011, 34(12):121-125. DOI: 10.11835/j.issn.1000-582X.2011.12.020

[Abstract](1878) [HTML](0) [PDF 5.25 M](1885)

Abstract:
A new algorithm based on gradient optimization is proposed for optical flow estimation of video images with different motion ranges. The original video images are transformed by using Loggabor filtering on phases and measures，and then the spatio-temporal gradient is calculated by using the obtained feature images. The optical flow is calculated with the spatio-temporal gradient. The video images are layered and processed with coarse-to-fine image pyramid method. The theoretical analysis and experimental results show that the algorithm is suitable for the video optical flow motion estimation of the significant range. It can not only obtain the video images following the human visual resolution characteristics, but also optimize the spatio-temporal gradient, while the optical flow calculation is more accurate. Besides, the time complexity of this algorithm is equivalent to that of the traditional optical flow method, and the accuracy of the algorithm is superior to the methods suggested by Horn-Schunck, Duan，et al.

21 New shape descriptor with skeleton information statistics

TANG Jin , CHEN Zhan zhan , LUO Bin

2011, 34(12):126-131. DOI: 10.11835/j.issn.1000-582X.2011.12.021

[Abstract](1602) [HTML](0) [PDF 6.27 M](1178)

Abstract:
Two-dimensional structure-histogram based on skeleton is proposed for shape descriptor and shape recognition. The descriptor utilizes the shape skeleton information to achieve invariance of starting point, rotation, translation and scale of shape contour. The shape descriptor calculates the geodesic path distance ratio based on skeleton center and maximal disk radius ratio for each pair of skeleton points. The two structural features are combined to construct a new two-dimensional histogram matrix statistically for describing shape. The experimental results show that this shape descriptor not only has the characteristic of rigid invariance, but also achieves higher efficiency and retrieval precision in non-rigid situation.

22 Free vibration characteristic analysis of the elastic liquid-storage tanks based on the bending shearing model

CHENG Xuan sheng , ZHENG Ying ren

2011, 34(12):132-137. DOI: 10.11835/j.issn.1000-582X.2011.12.022

[Abstract](1472) [HTML](0) [PDF 5.46 M](1024)

Abstract:
Liquid-storage tanks, mostly used to reserve rinsing, sewerage, petroleum and chemistry liquid, are broadly applied in such industry corporations as water-supply and drainage industry, sewerage-disposal industry, petroleum industry, chemistry industry and so on. For the sake of computing preferably earthquake responding of these structures, the characteristics of their free vibration, like frequency of free vibration and corresponding oscillation-mode, have to be known beforehand. Therefore, for the liquid-storage tanks without liquid, the equations about oscillation-mode and frequency based on bending-shearing model are deduced, and at the same time, the calculation tables and chart of former three oscillation-modes are presented by using MATLAB program, and free vibration characteristics using different deformation theory in different heights are analyzed. The correctness of the result is proved by calculation example, and a theory base is provided for analyzing subsequent free vibration and earthquake responding of this type of structure.

23 Rehabilitation project of the Dabanshan highland road tunnel

LIU Hai jing , ZHENG Jia yan , CHENG Chong guo , HUANG Lun hai

2011, 34(12):138-143. DOI: 10.11835/j.issn.1000-582X.2011.12.023

[Abstract](1573) [HTML](0) [PDF 9.49 M](1498)

Abstract:
The rehabilitation project of road tunnel in highland area and cold region is an important and worthy exploring research field. The development of the defects of crack in the liner, water leakage, structural deterioration and frost defects for Dabanshan road tunnel are studied. After an insight into the cause and development of tunnel defects, the water leakage and frost damage are considered as the root of defect, so restoration of drainage system and the reinstallation of cold prevention system are the focuses of the rehabilitation project. For consideration of safety, cover arch is installed for the tunnel structure enforcement as well. Results indicate measures in Dabanshan road tunnel rehabilitation project are effective for road tunnel of high altitude and tunnel in cold region.

24 Analysis of salt rock underground deposit failure probability in operation period based on response surface method

LIU Jian , SONG Juan , ZHANG Qiang yong , JIA Chao , LI Shu cai

2011, 34(12):144-150. DOI: 10.11835/j.issn.1000-582X.2011.12.024

[Abstract](1824) [HTML](0) [PDF 7.45 M](1080)

Abstract:
For the safety of salt rock underground deposit, uncertainties and their influences are considered, and failure probability during operation period is analyzed. Based on finite element model, equation of limit state surface is transformed into explicit equation by response surface method. Combined with Monte Carlo method, computation efficiency is improved. The deposit could be simulated as a series-parallel system. The element with highest failure probability is determined first, then failure mode and system reliability are computed. Taking Jintan underground gas deposit as an example, the analysis indicates that as storage pressure increases, failure probability of middle part of deposit decreases firstly, then increases gradually when storage pressure accumulates to a certain extent. The failure probabilities of upper part and underside of deposit increase as storage pressure increases. During operation period, controlled failure mode is shear failure of upper part and underside of deposit under high storage pressure. In conclusion, the storage pressure during operation period should be controlled strictly.

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