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15 February 2008, Volume 29 Issue 2 Previous Issue    Next Issue
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Application of PSO to multimodel self-tuning dynamic matrix control Yue, Heng (1); Zhang, Hai-Jun (1); Chai, Tian-You (1) 2008, 29 (2):  153-156+165.  DOI: - Abstract ( 220 )   HTML   PDF (364KB) ( 523 )   To obtain the fixed models in multimodel control problem, the PSO (particle swarm optimization) algorithm is applied to multimodel self-tuning dynamic matrix control. For a class of SISO discrete time systems with jumping model parameters, the PSO algorithm is used to optimize the self-tuning model parameters online and manage dynamically the fixed models in accordance to the similarity between models, so that the number of models may be handled and system burden can be reduced effectively. Model switching tactics is used to select the controller best to describe the actual controlled system. Simulation results show that the method proposed can improve the transient response greatly in comparison with conventional control algorithms and demonstrate its efficiency and feasibility. References | Related Articles | Metrics

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Sliding mode AQM algorithm for TCP networks with uncertainty Yan, Ming (1); Jing, Yuan-Wei (1); Shen, Xiao-Jun (2) 2008, 29 (2):  157-160.  DOI: - Abstract ( 237 )   HTML   PDF (304KB) ( 679 )   An active queue management (AQM) algorithm based on sliding mode control (SMC) theory is proposed to solve the congestion problem in transmission control protocol (TCP) networks. The algorithm is put forward on the basis of linear TCP network congestion control model. An asymptotically stable sliding surface is designed by linear matrix inequality (LMI) to compensate for the effect of uncertainty in networks. In this way the design of the sliding surface is transformed into solving the LMI. Applying an improved reaching condition to the congestion control system, the chattering is obviously decreased. The controller satisfying the reaching condition can effectively constrain the oscillation of the queue length in router. The simulation results in different scenarios demonstrate the favorable stability and robustness of the algorithm. References | Related Articles | Metrics

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On the sliding mode control of uncertain time-delay TCP/AQM system Wang, Hong-Wei (1); Qian, Xiao-Long (1); Jing, Yuan-Wei (1); Liu, Xiao-Ping (1) 2008, 29 (2):  161-165.  DOI: - Abstract ( 266 )   HTML   PDF (292KB) ( 558 )   For the transmission control protocol (TCP) linear dynamic systems with input time-delay and unmatched uncertainties, a special linear transformation was done to transform an uncertain time-delay system into a delay-free system. Then, an active queue management (AQM) algorithm based on sliding mode control (SMC) was designed in the new coordinate system. A new SMC strategy is proposed satisfying the sliding mode reaching conditions, and LMI-based method was given to design the robust sliding hyperplane so as to verify the system stabilization via Lyapunov function. Simulation results showed that the algorithm enable the queue length to converge to its set value quickly and keep the queue oscillation small. The simulation also showed that the algorithm outperforms the conventional SMC strategies with its high robustness and accurate trackability in case the network conditions change. References | Related Articles | Metrics

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State transition method for robot program design Wang, Ming-Shun (1) 2008, 29 (2):  166-169.  DOI: - Abstract ( 301 )   HTML   PDF (465KB) ( 1417 )   To solve the complex design problem of control program of robots in different applications, the state transition method is proposed. According to the FSM theory and the working state that changes with robot action, three examples of program design were given for state transition, i.e., the sorting manipulator of a semiautomatic X-ray crystal axial angle sorter, the robot as an simple intelligent car and the multiple manipulators to coordinate jobs. The results demonstrated that the state transition method is feasible and valid to robot program design and available to simplify the design of some robot control programs. References | Related Articles | Metrics

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Time-fractional transmission line model and its simulation Zhang, Yan-Zhu (1); Xue, Ding-Yu (1) 2008, 29 (2):  170-173.  DOI: - Abstract ( 196 )   HTML   PDF (497KB) ( 796 )   In view of the fluctuating propagation of voltage/current wave in transmission line, a generalized time-fractional equation is used for transmission line to express the abnormal diffusion process of the voltage/current wave. Introducing the Adomian decomposition method, transient analysis is made to the generalized equation with a simulation done as instance for lossless transmission line. Simulation results showed that introducing the derivative of the time-fractional equation into the lossless transmission line model is available to express well the transient characteristics of the propagation/diffusion process of voltage/current wave in such a line, and it is of practical importance to the transient analysis of transmission line. In comparison with the conventional fractional Laplace algorithm, the method proposed is shorter in simulating time, and simpler in computation with less data required. References | Related Articles | Metrics

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Detection based on support vector machine interpolation for copper electrolytic composition Yuan, Ping (1); Li, Yan (1); Mao, Zhi-Zhong (1) 2008, 29 (2):  174-177.  DOI: - Abstract ( 226 )   HTML   PDF (1257KB) ( 472 )   In the process of electrolytic copper production the contents of copper ions and acid ions can only be detected once each day through tests, and they arc inadequate to showing the regularity of variation of copper electrolyte composition. It was found that the values for conventional interpolation often differ greatly from the values obtained actually in site. To solve the problem, a soft measurement model is advanced considering the influencing factors on measurement with relevant data forecasted efficiently. The support vector machine is introduced to improve linear interpolation because of its advantages in developing the soft measurement model. And a method is given to determine the weights for the values estimated by the soft measurement and values for conventional linear interpolation. The approach proposed ensures not only the time continuity of data but also the values for interpolation to approximate to actual values. Simulation results showed its effectiveness. References | Related Articles | Metrics

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Decentralized robust stabilization for large-scale descriptor systems Teng, Yu-Fa (1); Zhang, Qing-Ling (1); Zhang, Ming-Xue (2); Hao, Jian-Zhong (2) 2008, 29 (2):  178-180+184.  DOI: - Abstract ( 373 )   HTML   PDF (159KB) ( 566 )   According To the restricted equivalent decomposition of matrix pencil in the regular and impulse-free (removal of impulse) descriptor system, the order reduction was done further for the system to solve the problem of decentralized robust stabilization of uncertain interconnected large-scale descriptor systems. By the theory of linear matrix inequalities, the sufficient conditions are given to the robust stabilization of both uncertain descriptor systems and uncertain interconnected large-scale descriptor systems, as well as the design method of the relevant state feedback controller. The difference between static and dynamic modes in the abilities to overcome the uncertainties, resist interference and eliminate the influence of relevant terms is also revealed. References | Related Articles | Metrics

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Non-invasive prosthetic vision system for the blind via auditory pathway Yang, Dan (1); Zhang, Fu-Mei (1); Xu, Bin (1); Wang, Xu (1) 2008, 29 (2):  181-184.  DOI: - Abstract ( 581 )   HTML   PDF (898KB) ( 1127 )   Proposes a non-invasive prosthetic vision system via auditory pathway for blind people. The system acquires the surrounding information to which the EBCOT (embedded block coding with optimized truncation) algorithm is used before using the wavelet transform to code ROI (region of interest). Then, the data for image restructuring are obtained via the surrounding information transmission and decoding. The data are scanned in terms of polar coordinates, from which the coordinate information on each and all pixels and their gray levels in an image are mapped into the time, frequency and oscillation amplitude of acoustic signals which are then synthesized together in sine-wave form. The results showed that the image data can be coded and transmitted quicker to acquire more information if using EBCOT algorithm, and the acoustic signals have better recognizability if scanning image data in terms of polar coordinates for mapping. References | Related Articles | Metrics

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Searching business information with Hopfield neural network in electronic commerce environment Wang, Zheng (1); Wang, Qing (1); Wang, Ding-Wei (1) 2008, 29 (2):  185-188+192.  DOI: - Abstract ( 266 )   HTML   PDF (347KB) ( 607 )   Analyses the problem of searching business information in electronic commerce (EC) environment, and proposes a search method using Hopfield neural network with Internet as information source through artificial intelligence (AI) and information retrieval (IR) theory. In this method the features of business information are represented in terms of connection weights. A set of extended query terms are generated automatically by Hopfield neural network in accordance with the query keywords the users input. Searching general-purpose search engine (GSE) with those extended query terms and ranking the results, the proposed method can expand the search scope and improve the search precision so as to provide valuable business information for enterprises. References | Related Articles | Metrics

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GA integrated with repulsion operator to solve uncapacitated multi-level lot-sizing problem Han, Yi (1); Tang, Jia-Fu (1); Mu, Li-Feng (1); Wang, Xiao-Qing (1) 2008, 29 (2):  189-192.  DOI: - Abstract ( 237 )   HTML   PDF (1103KB) ( 520 )   Research on the multi-level lot-sizing (MLLS) problem in discrete manufacturing industry is not only theoretically but computationally hard. The solution to MLLS problem plays a very important role in gaining economic effectiveness during production process. To avoid the decrease in search efficiency caused by prematurity, the repulsion operator was integrated into GA (RGA) to solve uncapacitated MLLS problem with assembly structure. Simulation tests were conducted introducing both GA and RGA for 6 groups of MLLS problems of different sizes, and the computational results showed that RGA is obviously superior to GA and that RGA is an effective method to solve MLLS problem. References | Related Articles | Metrics

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On the link quality measurement in wireless sensor network Zhao, Hai (1); Zhu, Si-Yuan (1); Sun, Pei-Gang (1); Zhang, Xi-Yuan (1) 2008, 29 (2):  193-196.  DOI: - Abstract ( 225 )   HTML   PDF (400KB) ( 830 )   Several influencing factors on the link quality of WSN were discussed and, based on the protocol in the standard IEEE802.15.4, the formats of MAC data frame and the mechanism of data transmission were amended. Then, a method was designed to measure the link quality of WSN so as to avoid the influence of different frame lengths and enable the wireless sensor nodes to acquire data better from communications link. Measurement was carried out according to the standard IEEE 802.15.4 and the amended method separately, and measured data were analyzed, compared and evaluated. References | Related Articles | Metrics

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Research on simulation of ad hoc MAC layer protocol Zhao, Hai (1); Yuan, Shao-Qian (1); Zhang, Xin (1); Li, Chao (1) 2008, 29 (2):  197-200.  DOI: - Abstract ( 199 )   HTML   PDF (935KB) ( 699 )   Recently most researches on ad hoc network were conducted by simulation. As to the simulation of MAC protocol, the large simulation softwares are usually difficult to use and inaccurate. A small-size ad hoc MAC protocol simulator is therefore designed to study relevant network protocol, which simulates physical channel with data byte as minimum processing unit that is suitable for studying MAC protocol. With the network activities visualized, it is convenient for early development and debugging of MAC protocol. This simulator is designed with an object-oriented method and multi-thread protocol model to provide well its extensibility and introduce a class of RXMitter to solve the synchronization problem. In addition, a new traffic model is proposed which is more suitable for MAC protocol simulation. An implementation method and related tests are given to the simulator. References | Related Articles | Metrics

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QoS multicast routing algorithm based on mind evolutionary computation and game theory Wang, Jun-Wei (1); Wang, Xing-Wei (1); Huang, Min (1) 2008, 29 (2):  201-204+212.  DOI: - Abstract ( 270 )   HTML   PDF (215KB) ( 836 )   Taking the characteristics of multi-constraint QoS (quality of service) routing in NGI (next generation Internet) into account, a QoS multicast routing algorithm based on MEC(mind evolutionary computation) and game theory is presented. It introduces the membership functions to evaluate the adaptability of candidate edges to users requirements for QoS; makes sure of whether the network provider has been in Nash equilibrium with users in respect to the utility on edges through gaming analysis; constructs a multicast routing tree via MEC so as to enable users' QoS requirements to be satisfied and the utility of both network provider and users to reach or approach Pareto optimum when both are in Nash equilibrium. Simulation results showed that the proposed algorithm is feasible and effective. References | Related Articles | Metrics

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Performance and simulations of improved adaptive iterative decoding algorithm of turbo codes Zhang, Zhen-Chuan (1); Wang, Jian-Ying (1) 2008, 29 (2):  205-208.  DOI: - Abstract ( 206 )   HTML   PDF (287KB) ( 1003 )   Increasing the number of iteration steps can decrease BER (bit error rate) but increase time-delay. A compromise is reached between the errors and time-delay, and an adaptive iterative decoding algorithm is improved through an investigation on the principle of turbo codes and iterative decoding technique, in which a novel strategy is introduced to determine when to terminate the iterative process. Using the tail bits generated from decoder to detect errors and designing properly the minimum number of iteration steps can efficiently reduce the average number of iteration steps with low BER. Computer simulation showed that the improved algorithm can efficiently decrease the time-delay. References | Related Articles | Metrics

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Algorithm of finding and recovering a QoS-aware service path Wang, Hui (1); Yang, De-Guo (1); Gao, Yuan (1); Wang, Cui-Rong (1) 2008, 29 (2):  209-212.  DOI: - Abstract ( 284 )   HTML   PDF (892KB) ( 693 )   A new approach is presented to studying QoS-aware service combination. An interference model is proposed to quantitatively characterize and measure how the interference affects the service provided for users. The interference intensity is defined as the substituted number of nodes per unit time when recovering a service path. To reduce the service routing computation, an efficient routing algorithm is designed, with three optional strategies for simplified routings provided, i.e., lazy adjustment, selecting reliable nodes and local path recovery. Then, based on the three strategies and the interference model proposed, an optimized minimum interference service routing algorithm is given. The results showed that both the algorithm and model proposed can reduce the interference on end users and improve the system robustness and stability when finding service paths. References | Related Articles | Metrics

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Microstructure and mechanical properties of pipeline steel X80 Yi, Hai-Long (1); Du, Lin-Xiu (1); Wang, Guo-Dong (1); Liu, Xiang-Hua (1) 2008, 29 (2):  213-216.  DOI: - Abstract ( 343 )   HTML   PDF (604KB) ( 937 )   The microstructure and mechanical properties of pipeline steel X80 were investigated by means of optical electron microscope, scanning electron microscope, transmission electron microscope, etc. The experimental results showed that the yield strength of pipeline steel X80 with 16mm wall thickness can be up to over 670 MPa through controlled rolling/cooling, and the ratio of tensile strength to yield strength and ductile-brittle transition temperature are lower than 0.85 and-60°C, respectively, thus providing a nice match between strength and toughness. Fine acicular ferrite has good effect on both the strength and toughness of the steel. Two kinds of precipitates were observed in the steel, where the coarse ones are mainly the Nb and Ti(CN) ranging from 50 nm to 200 nm, and the fine ones are mainly NbC less than 30 nm. Both the nano-precipitates play an important role in strengthening and grain refinement of the steel. References | Related Articles | Metrics

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Effects of deformation at room temperature on the precipitates in low carbon steel Yao, Sheng-Jie (1); Du, Lin-Xiu (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2008, 29 (2):  217-220.  DOI: - Abstract ( 228 )   HTML   PDF (603KB) ( 601 )   For a kind of low carbon micro-alloy steel, a thermal simulation test was conducted with samples of F+B+P microstructure and the effects of its cold deformation at room temperature on the distribution, size and composition of precipitates were investigated via a technological process for rapid heating and short holding time. The results indicate that the dispersity of the precipitates increases with the change in dislocation density which is influenced by the deformation at room temperature, while the size of the precipitates decreases to a certain extent. And the size of equiaxed grains decreases with increasing deformation at room temperature in view of their morphology. Also, the deformation at room temperature can expedite the vanadium precipitation to a certain extent because of its high solubility. References | Related Articles | Metrics

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Effect of Nb on low-carbon Si-Mn steel during continuous cooling transformation Shang, Yan (1); Ding, Hua (1); Li, Long (1) 2008, 29 (2):  221-224.  DOI: - Abstract ( 210 )   HTML   PDF (1095KB) ( 493 )   The continuous cooling transformation (CCT) tests of low-carbon Si-Mn steel were conducted on Gleeble 1500 thermal simulator with and without Nb addition, and the relevant curves were plotted under deformed and undeformed conditions. The results showed that the undeformed CCT curves mostly go down due to the effect of Nb addition that lowers the phase transformation temperature of ferrite (Ar3), while the deformed CCT curves go up due to the effect of strain-induced precipitates as Nb(C, N), which raises Ar3 hence lowers the starting cooling rate in banite transformation. Moreover, ferrite grains were refined obviously with the addition of Nb under deformed conditions, thus hardening greatly the tested steel. References | Related Articles | Metrics

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Effect of sol-gel process on morphology of powdered silicon carbide Qiu, Rong-Peng (1); Cai, Qing-Kui (1); Zhang, Ning (2) 2008, 29 (2):  225-228.  DOI: - Abstract ( 492 )   HTML   PDF (445KB) ( 960 )   Silicon carbide precursor was prepared by sol-gel method using tetracthyl orthosilicate (TEOS) and active carbon as raw materials. Then, the powdered silicon carbide was synthesized by carbonthermal reduction reaction at 1400-1600°C. Such a powdered silicon carbide is a mixture of particles and whiskers. The pyrolysis process of silicon carbide precursor was analyzed by thermogravimetric (TG) and differential scanning calorimetry (DSC), and the composition and structure of powdered silicon carbide synthesized at different temperatures was analyzed by X-ray diffraction. The effects of the volume ratio of ethanol (EtOH) to TEOS and ammonia concentration on the morphology of products were investigated with the formation mechanism of silicon carbide whiskers and particles discussed preliminarily. References | Related Articles | Metrics

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FTA-based analysis of internal cracks in continuous casting billet and optimum control Liu, Wen-Hong (1); Xie, Zhi (1); Chen, Xiao-Hui (1); Jia, Guang-Lin (2) 2008, 29 (2):  229-232.  DOI: - Abstract ( 241 )   HTML   PDF (462KB) ( 1265 )   To improve the internal quality of continuous casting billet, a new approach to quality analysis and optimum control is proposed on FTA Basis. The interrelation between different hypotheses of the formation mechanism of internal cracks is studied to find out the root causes. According to the features of FTA and expertise, an FTA model of internal cracks is developed, then the software VC++ 6.0 is introduced to form the visual-FTA system, which is available to generate and analyze the fault tree automatically. Applying the analysis system to the steel Q235 supplied by a steel-maker, the qualitative/quantitative results basically conform with the on-line statistical ones, then an optimum control scheme is proposed to improve the billet quality. References | Related Articles | Metrics

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Influence of mesh and time-step on transient temperature oscillation Mei, Rui-Bin (1); Li, Chang-Sheng (1); Liu, Xiang-Hua (1) 2008, 29 (2):  233-236.  DOI: - Abstract ( 202 )   HTML   PDF (643KB) ( 990 )   Analyzing the phenomenon and causes of transient temperature oscillation during the FEM solution to temperature field. The influences of different element meshing methods and time-step on the transient temperature oscillation were discussed. Refining the elements and S-type time-variable steps were proposed. The calculation results showed that refining the elements layer upon layer not only restrains the transient temperature oscillation so as to come to the required calculation accuracy but also reduces the calculating time. Compared to the fixed steps, the S-type time-variable steps can shorten more than 10 times the calculating time with the oscillation restrained, accuracy ensured and other conditions kept constant. The results were theoretically and practically important to improve calculation accuracy and expedite calculation speed. References | Related Articles | Metrics

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Development and application of computer software for welding heat cycle Feng, Ying-Ying (1); Luo, Zong-An (1); Zhang, Dian-Hua (1); Wang, Li-Jun (1) 2008, 29 (2):  237-240.  DOI: - Abstract ( 198 )   HTML   PDF (1096KB) ( 625 )   The software for welding heal cycle was developed successfully, based on some classical mathematic models and measured data and programmed appropriately by LabVIEW7.1. It is available to plot the curve of welding heat cycle conveniently and quickly so as to reflect and describe quantitatively the main influencing factors on the parameters of heat cycle and the correlation among them. This software comprises 7 kinds of welding methods and each of them is based on its own mathematic model and applies to relevant field. It can support 10 passes at most in the simulation of welding heat cycle, and the software interface is simple and easy to operate. By virtue of its stability, reliability and convenience, the software has been applied to MMS-200 thermal simulator. References | Related Articles | Metrics

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Fourier-Chebyshev collocation spectral Poisson solvers in polar and cylindrical coordinate systems Li, Ben-Wen (1); Yu, Yang (1); He, Ji-Cheng (1) 2008, 29 (2):  241-245.  DOI: - Abstract ( 590 )   HTML   PDF (2279KB) ( 1295 )   The Poisson silvers in polar and cylindrical coordinate systems are developed using Fourier-Chebyshev collocation spectral method based on matrix-matrix multiplication. Usually the singularities will appear in the solution to Poisson equation in polar and cylindrical coordinate systems by spectral method. To avoid such a problem, two methods are proposed to solve the Poisson equation. The first is introducing the Gauss-Radau collocation points, thus excluding the singularity at the origin. The second method is transforming the computing interval [0, 1] in radial direction into [-1, 1] and then introducing the Gauss-Lobatto collocation points, so as to exclude the singularity at the origin when the number of nodes is odd. And no extra pole conditions are required by both methods to avoid the singularity at the origin. The two methods are compared with each other and verified via 2D and 3D instances separately, and the results indicate that they arc direct, fast, and highly accurate. References | Related Articles | Metrics

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Anti-corrosion testing of SiC-Si3N4 insulation sidelining for aluminum electrolysis Cao, Xiao-Zhou (1); Gao, Bing-Liang (1); Wang, Zhao-Wen (1); Zhang, Ting-An (1) 2008, 29 (2):  246-249.  DOI: - Abstract ( 267 )   HTML   PDF (824KB) ( 517 )   A new method was applied to the test of corrosion resistance of SiC-Si3N4 material. It refers to that the cryolite-alumina melt is aerated so as to simulate a working state inside the cell during Al electrolysis, then a specimen is put into a graphite crucible where the high-temperature molten salt was contained before. The CO2 aeration makes the specimen dynamically corrosive. Then, the volume change rate of the specimen under the joint action of electrolyte and CO2 gas is tested and compared with the data resulting from static electrolyte corrosion test. The specimen presents much higher corrosion. It means that CO2 gas has greater effect on corrosion resistance. The new dynamic corrosion method was applied to the SiC-Si3N4 samples supplied by three different firms and, according to the testing standard based on the method, the results were evaluated for their anti-corrosion properties. The method is simple and efficient to simulate the corrosion behavior of the inner lining materials in aluminum electrolysis cell and evaluate their anti-corrosion properties. References | Related Articles | Metrics

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Simulation of dynamic characteristics of faulty multi-span rotor system through FEA Li, Xiao-Peng (1); Gong, Zhao-Min (1); Liu, Jie (1); Wen, Bang-Chun (1) 2008, 29 (2):  250-253.  DOI: - Abstract ( 308 )   HTML   PDF (299KB) ( 762 )   The vibration characteristics of faulty multi-span geared rotor system with membrane coupling was modeled and simulated through the FEA (finite element analysis) software ANSYS. The nonlinear dynamic characteristics and responses of the rotor system, and the influences of membrane coupling and gearing on the rotor system were studied according to the change in inherent frequency due to bending-torsioning coupled vibration in the single-span rotor and the whole rotor system when cracks and rubbing fault happen. The results indicated that in such a case the influence on a faulty span is greater than on rests, and the adverse influences of bending vibration and cracks on the rotor system can be weakened or retarded by membrane coupling and gears. What were revealed is beneficial to the fault diagnosis and system maintenance and available to provide reference for designing products. References | Related Articles | Metrics

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CAN bus based PSA fault diagnosis system for engines Liu, Ying-Ji (1); Zhang, Tian-Xia (1); Wen, Bang-Chun (1); Yang, Jing-Feng (1) 2008, 29 (2):  254-257+261.  DOI: - Abstract ( 312 )   HTML   PDF (504KB) ( 964 )   Based on CAN bus, a new online PSA (PCA-subtractive-ANFIS) fault diagnosis model is proposed to solve the problems that the conventional engine fault diagnosis cannot be predicted and are hard to inquire about their happenings. With the state data acquired by ECU (electronic control utilities) sensors and transmitted by CAN bus for all the elements of an engine taken as samples for diagnosis, the diagnosis model is developed the way the PCA (principal component analysis) is used for dimensions' reduction and decorrelation and the subtractive clustering algorithm is introduced to complete the fuzzy inference process, then the adaptive-network-based fuzzy inference system (ANFIS) is applied to the new type model. Simulation results showed that the PSA model is superior to PCA-BP network model in fitting, denoising and convergence rate. References | Related Articles | Metrics

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Recognition based on wavelet neural network for sucker rod's defects Sun, Hong-Chun (1); Yan, Zhi-Ying (1); Xie, Li-Yang (1) 2008, 29 (2):  258-261.  DOI: - Abstract ( 188 )   HTML   PDF (508KB) ( 534 )   Sucker rod is an integral part of the oil well pumping. To reduce the rupture possibility of the rod, it is important to recognize correctly its defects. Discusses the way to recognize the defects by using wavelet transform in combination with neural network. Based on the principle of wavelet package, the signals in time domain detection arc decomposed and enter into every frequency band within which the energy is extracted as an input to BP neural network by the momentum-range method for adaptive learning speed gradient descent, then the output reveals the sucker rod's defects including crack, corrosion pits, partial wear, impairments and indefectible rod. Testing results with lots of data acquired in lab showed that the way to recognize the defects of sucker rod involves both the single and mixed defects. References | Related Articles | Metrics

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Research on the order sectioning analysis based on even-time sampling rate and its application Zhang, Zhan-Yi (1); Liu, Jie (1); Ying, Huai-Qiao (2); Fu, Xiao (3) 2008, 29 (2):  262-265.  DOI: - Abstract ( 422 )   HTML   PDF (1038KB) ( 629 )   A phenomenon named frequency smear will happen to the characteristics of nonsteady malfunction in rotary machine system when making a conventional frequency spectrum analysis. To make up for the deficiency of conventional frequency spectrum analysis and establish the relationship between the malfunction characteristics and rotating speed, the waveform restructuring technique is used to develop the order sectioning analysis based on even-time sampling rate. A typical misalignment fault testing is therefore designed to perform on a rotor test stand so as to analyze the relevant signals by way of the order sectioning analysis. The results showed that the order sections can characterize the double/triple frequency of a misalignment fault in rotary machine system and the variation of its harmonic components with rotating speed. The order sectioning analysis is thus proved recognizable to the characteristics of nonsteady malfunctions to a certain extent. References | Related Articles | Metrics

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Experimental study on ultrasonic exploration in unknown environment Luo, Zhong (1); Liu, Hong-Yi (1); Wang, Fei (1); Sun, Yi-Lan (1) 2008, 29 (2):  266-269.  DOI: - Abstract ( 220 )   HTML   PDF (1242KB) ( 696 )   A new exploring method is presented for a robot carrying ultrasonic sensors to work in unknown environment. With a structural model developed for the exploring system and its operating principle described, an experimental investigation was done on some different surfaces which form basically an unknown and unstructured environment, such as plane, circular, inclined and vertical surfaces. The experimental results showed that the ultrasonic rangefinder doesn't fit to explore the circular surface of small radius of curvature. As for the other three surfaces, different ways were proposed for exploration and data processing separately as a result of the experimental study, i.e., three ultrasonic sensors arc necessary for inclined surface; the dynamically measuring errors resulting from patulous angle should be compensated for vertical surface; moving sensors should be compensated for plane surface. References | Related Articles | Metrics

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Decomposition effect of ecological footprint of traffic in Shenyang Sun, Peng (1); Wang, Qing (1); Liu, Jian-Xing (1); Gu, Xiao-Wei (1) 2008, 29 (2):  270-272+276.  DOI: - Abstract ( 228 )   HTML   PDF (739KB) ( 480 )   Based on a decomposition model developed for the ecological footprint of traffic, the ecological footprints of traffic in Shenyang from 1995 to 2004 were analyzed. The results showed that, generally, the number of footprints increased year by year, while the different influencing factors on them played different roles in making contributions to the footprint growth in different periods. The change in traffic volume always embodied the increment effect on ecological footprint, in which cars made the greatest contribution to the traffic footprint, but, as a whole, the magnitude of increment tended to be stable and slow. In the period from 1995 to 2004, the effect of the change in ecological footprint intensity/structure showed fluctuation to a certain degree to reflect the difference in the impact due to environmental pressure caused by the economic development and policy alteration. In view of the research results in combination with the sustainable trend of urban traffic development, some suggestions are put forward as the policies to reduce the environmental pressure acting on Shenyang's traffic. References | Related Articles | Metrics

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GIS-based diffusion model of environmental pollution Bi, Tian-Ping (1); Jin, Cheng-Zhu (1); Zhong, Sheng-Jun (2); Shang, Jian-Hong (3) 2008, 29 (2):  273-276.  DOI: - Abstract ( 871 )   HTML   PDF (573KB) ( 2783 )   Some mathematical models were developed to forecast pollutant diffusion into atmosphere or water. Introducing the GIS (geographic information system), the models were simulated and displayed at the place where pollution hazard actually happened on the map of Shenyang City. Integrating the numerical solutions to models with GIS and analyzing the spatio-temporal diffusion of pollutants, the diffusion areas were worked out for different pollutants at different time to analyze the pollutant density and pollution intensity and what's more the important information on population and facilities near the polluted area can be acquired. Thus, it is available to forecast how heavy a pollution hazard affects the environment and nearby people especially an accidental pollution hazard, including the hazardous extent and level. Such a forecasting method lays a scientific base for emergency monitoring, field rescue and evaluation after a hazard. References | Related Articles | Metrics

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Study on variogram robustness Sun, Li-Shuang (1); Wang, En-De (1); Liu, Guo-Hua (2); Mao, Ya-Chun (1) 2008, 29 (2):  277-279.  DOI: - Abstract ( 220 )   HTML   PDF (674KB) ( 676 )   The sample data acquired in the process of geological exploration often deviate from normal distribution. So, the calculating values from relevant variogram will deviate from their real values. Analysing the distribution characteristics of ore-forming elements in samples, a method of calculating variogram by robust estimation is proposed to study the spatial ore-forming variability. Samples are available to obey normal distribution through exponential transform, then the variogram is calculated separately by median and tri-mean methods of robust estimation. The model optimization of variogram is verified according to crass-validation, and the result shows that the estimated value can get higher accuracy by means of robust estimation to calculate variogram. References | Related Articles | Metrics

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Durability of the corrosion-resistant concrete in saline soil area Jiang, Wei-Dong (1); Chen, Xiao (1); Yan, Jun (1); Liu, Bin (1) 2008, 29 (2):  280-283.  DOI: - Abstract ( 279 )   HTML   PDF (961KB) ( 921 )   A kind of corrosion-resistant concrete in which fly ash and water-reducing agent were both added was developed to adapt to the special geological and hydrographic conditions in Northwest China saline soil area. A lab test was performed to investigate the properties of the concrete, such as corrosion resistance, impermeability, carbonization resistance and freeze-thaw resistance, and a field test was done in the saline soil area for the concrete's impermeability and corrosion resistance. The relationships between the amount of fly ash additive and durability indices of such resistances were found. The results showed that adding fly ash and water-reducing agent in the concrete can improve its performance to resist sulphate corrosion and permeation, but fly ash has adverse effect on carbonization resistance. And the existing two-additive compound formulation lowers the freeze-thaw resistance. By a comprehensive analysis, the compound formulation that the fly ash amount is 40% in both additives is recommended for the concrete to be used in the saline soil area, which is available to provide higher durability indices of all resistances as above. References | Related Articles | Metrics

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- - 2008, 29 (2):  284-286.  DOI: - Abstract ( 310 )   HTML   PDF (94KB) ( 1257 )   - References | Related Articles | Metrics

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- - 2008, 29 (2):  287-291.  DOI: - Abstract ( 263 )   HTML   PDF (209KB) ( 743 )   - References | Related Articles | Metrics

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