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15 November 2009, Volume 30 Issue 11 Previous Issue    Next Issue
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Adaptive neural network control for a class of nonlinear discrete-time systems Zhai, Lian-Fei (1); Chai, Tian-You (1) 2009, 30 (11):  1521-1525.  DOI: - Abstract ( 331 )   HTML   PDF (385KB) ( 716 )   For a class of single-input-single-output nonlinear discrete-time systems with unknown control direction, an adaptive neural network control was developed by incorporating a conventional incremental digital PID (proportional-integral-derivative) controller in an adaptive neural network term to guarantee the stability of the closed-loop systems. The conventional PID controller was utilized to stabilize the approximate linear system, while the adaptive neural network was introduced to deal with the influence of nonlinear terms on closed-loop systems. A discrete Nussbaum gain was introduced into the adaptation law of the weights in neural network to resolve the unknown control direction problem. It was proved that all signals of the closed-loop system are bounded with the tracking error converges on a compact set. Simulation results verified the effectiveness of the proposed control method. References | Related Articles | Metrics

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Intelligent control system of fused magnesia production via rule-based reasoning Wu, Zhi-Wei (1); Wu, Yong-Jian (1); Chai, Tian-You (1); Zhang, Li (1) 2009, 30 (11):  1526-1529.  DOI: - Abstract ( 274 )   HTML   PDF (1138KB) ( 727 )   Traditional manual process control of electric furnace smelting of magnesia has such disadvantages as high energy consumtion, poor-quality products and high labor intensity. To solve those problems, an auto-control method was proposed for the smelting process through combining the control rules which were summed up from operational experience acquired in manual control process with relevant control theory. Then, based on this method and rule-based reasoning, an intelligent control system was designed for the electric furnace smelting of magnesia, involving some models developed for current presetting, regulation/compensation for current unbalance and self-learning of current deviation threshold, as well as the recognizer of working conditions and electrode lifting controller. The intelligent control system has been introduced in a domestic magnesia smeltery with successful results obtained in application. References | Related Articles | Metrics

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A hardware-in-the-loop simulation platform for optimized intelligent control of industrial process Tang, Jian (1); Chai, Tian-You (1); Pian, Jin-Xiang (1); Yue, Heng (1) 2009, 30 (11):  1530-1533.  DOI: - Abstract ( 294 )   HTML   PDF (568KB) ( 1019 )   Characterized with multi-variable, strong coupling and high nonlinearity/uncertainty, it is hard to debug and test the automation system and relevant optimal control softwares fully on the site in actual industrial process. A distributed hardware-in-the-loop simulation platform is therefore developed for actual industrial process via combining the production process control system with the objects of which the processes are to be controlled virtually, thus providing an industrial environment where an efficient verification is available to the R&D of specially optimized intelligent control system. On such a platform several relevant rules are defined to develop the special control system with the platform tested by PID control loop. With the optimized intelligent system of laminar cooling of hot-rolled strip tested on the platform, the validity of the platform is verified. References | Related Articles | Metrics

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Hybrid intelligent control method for laminar cooling process of hot rolled strip Pian, Jin-Xiang (1); Chai, Tian-You (1) 2009, 30 (11):  1534-1537.  DOI: - Abstract ( 248 )   HTML   PDF (582KB) ( 517 )   It is hard to control the coiling temperature in a certain range since the existing laminar cooling process lacks the direct feedback during strip hot rolling. A hybrid intelligent control method was therefore proposed combining the mechanism models with case-based reasoning technology, i.e., composed of four modeling modules: to preset the number of valves of spray header to be opened in cooling zone, to forecast coiling temperature, to compensate for feedforward, to compensate for feedback. The method proposed was simulated with the actual operating data provided by a steel plant and the results showed that the setting value of the number of spray header valves to be opened can be readjusted automatically and timely according to the changing operation conditions, thus controlling the coiling temperature in the range the technical schedule requires so as to improve the microstructure and mechanical properties of the rolled strip. References | Related Articles | Metrics

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Non-fragile control for nonlinear systems with infinitely distributed time-delay Ma, Da-Zhong (1); Wang, Zhan-Shan (1); Feng, Jian (1) 2009, 30 (11):  1538-1541.  DOI: - Abstract ( 228 )   HTML   PDF (205KB) ( 460 )   A design method of non-fragile controller is proposed for a class of nonlinear systems with infinitely distributed delay. Two typical kinds of disturbed gains in controller are considered, i.e., independent of and dependent on controller gain, then the non-fragile controllers are designed, respectively, to ensure that the time-delay systems is asymptotically stable and satisfy the preset performance indices. The existence condition of the non-fragile controller thus developed is delay-dependent, which is available to get through LMI. The effectiveness of the proposed design method was verified by a simulation example. References | Related Articles | Metrics

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A new cultural algorithm based on hybrid of GA and PSO algorithm Hu, Guang-Hao (1); Mao, Zhi-Zhong (1); He, Da-Kuo (1) 2009, 30 (11):  1542-1545.  DOI: - Abstract ( 313 )   HTML   PDF (425KB) ( 664 )   A new cultural algorithm based on the hybrid of GA and PSO algorithm is proposed to solve the ″Premature″ problem of global search of PSO algorithm. With both PSO algorithm and GA included in the framework of cultural algorithm, a PSO main population space and GA belief population space are formed, and they can evolve independently in paralled to enable the belief population space to guide the main population space in due time so as to improve the global search ability of PSO algorithm and enhance the computation precision. Simulation results showed that the algorithm proposed is superior to PSO algorithm, GA and GA-PSO hybrid algorithm in optimized performance and efficiency. References | Related Articles | Metrics

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Performance evaluation for selection of supplier and decision-making based on evidential reasoning Fu, Yan-Hua (1); Zhang, Hua-Guang (2); Tang, Jia-Fu (2) 2009, 30 (11):  1546-1549.  DOI: - Abstract ( 222 )   HTML   PDF (254KB) ( 628 )   To solve the uncertain multiple attribute decision making (MADM) problem of the performance evaluation and selection of suppliers, a multi-level MADM model is developed quantitatively and qualitatively via the evidential reasoning(ER) for uncertainties. Combining ER with information transformation the quantitative and qualitative information are expressed in form of unified distribution evaluation according to the grades of synthesized attributes. Then, the basic probability distribution function involving the weights of attributes is deduced to integrate all the attributes together by ER algorithm, thus giving a comprehensive evaluation to the MADM problem. And the preferred ranking of suppliers is determined on the basis of the theory of multiple attribute utility. An example is given for the evaluation and selection of suppliers to verify the effectiveness of the proposed method. References | Related Articles | Metrics

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New approach to identify activity loops in business process: String reachable matrix Yuan, Hui-Lin (1); Wang, Lei-Zhen (1); Wang, Ding-Wei (1) 2009, 30 (11):  1550-1553.  DOI: - Abstract ( 214 )   HTML   PDF (1262KB) ( 450 )   The reachable matrix can only express the reachable relationship between two nodes, but observing the matrix is needed for identifying loops to which the higher the order of matrix, the harder the identification of loops. Based on reachable matrix, a new approach is proposed to seek for unreasonable activity loops, i.e., the string reachable matrix(SRM). Showing the activity loops/paths in a matrix is therefore available via introducing strings into the matrix. Definitions and operational rules relevant to SRM are described in detail. The computing steps of SRM and how SRM finds out the activity loops/paths so quickly are exemplified. As one of the solutions to BPR, SRM provides a new way. References | Related Articles | Metrics

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Model and algorithm for distribution/delivery of goods on order in B2C e-commerce Li, Lin (1); Liu, Shi-Xin (1); Tang, Jia-Fu (1) 2009, 30 (11):  1554-1557.  DOI: - Abstract ( 317 )   HTML   PDF (182KB) ( 720 )   Discussing the characteristics of the orders placed by customers and what they require for the distribution and delivery of the goods on order in B2C e-commerce, a relevant mathematical model was developed with an improved tabu search algorithm designed and tested via numerical examples. And the testing results were compared with some earlier works as shown in the reference of this paper. It was found that the improved tabu search algorithm as a new approach is superior to GA-SA algorithm with memory function in both routing optimizing effect and computing time, and it is simple and easy to implement especially adaptable to the quick distribution/delivery of the goods on order in e-commerce. References | Related Articles | Metrics

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A clustering algorithm based on generalized similarity for co-regulated genes Zhao, Yu-Hai (1); Qiao, Bai-You (1); Lin, Tian-Liang (3); Wang, Guo-Ren (1) 2009, 30 (11):  1558-1561.  DOI: - Abstract ( 328 )   HTML   PDF (339KB) ( 812 )   A novel clustering model, i.e., the g-Cluster, is developed on the basis of generalized similarity for the special properties and disadvantages of existing clustering algorithms of co-regulated genes. The positive and negative co-regulated genes in this model are integrated into the same cluster if and only if they are provided with the same code. Further, a tree-based clustering algorithm FBTD (first breadth then depth) is proposed, where the priorities in search strategy is that the breadth is taken first then the depth, to find out all the maximal g-Clusters with high-efficiency pruning rules and optimizing strategy performed simultaneously. Applying the FBTD algorithm to real datasets involving genes, both the theoretic and testing results showed that the algorithm is practically efficient. References | Related Articles | Metrics

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A fuzzy extension of OWL based on F-ALC(G) Wang, Hai-Long (1); Ma, Zong-Min (1); Yan, Li (1); Yan, Dong-Liang (1) 2009, 30 (11):  1562-1565.  DOI: - Abstract ( 295 )   HTML   PDF (184KB) ( 698 )   The semantic web is expected to process fuzzy-concept knowledge and data-type information in an intelligent and automatic way. Recent researches showed that OWL has strict limitations on some aspects, i.e., it can't process imprecise and uncertain information which is so much in semantic web and its notology, and it does not support the data of self-defining type and the predicates relevant to them. A new fuzzy description logic F-ALC(G) is therefore introduced to break through the limitation, with its web grammar, syntax and semanteme given. Then, taking the F-ALC(G) as logical foundation and combining it with the web grammar/syntax norms RDF/XML, the descriptors in OWL are recoded to represent the fuzzy-concept knowledge so as to form f-OWL which is able to represent not only the fuzzy knowledge but also the data of self-defining type and the fuzzy information on the predicates relevant to them. A new representation is thus provided for the investigation on fuzzy notology. References | Related Articles | Metrics

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Buffer-control-based identification of rate control model of streaming media Zou, Yong (1); Zhao, Hai (1); Wei, Li-Feng (2); Gao, Wei (1) 2009, 30 (11):  1566-1569.  DOI: - Abstract ( 272 )   HTML   PDF (379KB) ( 452 )   It is common to regulate transmission rate from sending terminal to get a proper buffer length in multimedia synchronization. It is necessary to develop an accurate model between buffer length and transmission rate so as to apply the control theory to multimedia synchronization. A streaming media system is thus constructed on the NS2 to identify the rate control model via system identification. Analyzing the experimental data by the least squares estimator, the results showed that the rate control model of streaming media has the characteristic of integral time lag and verified that the identifying model is accurate. References | Related Articles | Metrics

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Preemptive control model based on time slice Xu, Jiu-Qiang (1); Liu, Hui (1); Zhu, Jian (1); Zhao, Hai (1) 2009, 30 (11):  1570-1573.  DOI: - Abstract ( 271 )   HTML   PDF (1323KB) ( 527 )   A preemptive control model based on time slice was developed for the task scheduling in real-time systems. Based on the premise that the schedulability of task set should be satisfied, the upper limit of the occurrence of preemption was taken as characteristic parameter to compute the time slice, then the occurrence of task preemption was optimized according to the restriction that any preemption is forbidden in the time slice. The genetic algorithm was introduced to enable the model to implement off-line operation and, simultaneously, the schedulability of a task set was ensured entirely via a penalty function. Simulation results verified the effectiveness of the model proposed. References | Related Articles | Metrics

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Analysis of degree distribution and its evolution of large-scale software macro-topology Li, Hui (1); Zhao, Hai (1); Xu, Jiu-Qiang (1); Ai, Jun (1) 2009, 30 (11):  1574-1577.  DOI: - Abstract ( 245 )   HTML   PDF (448KB) ( 606 )   Based on the metrics data acquired from a large number of source codes of open source softwares and the complex network characteristics embodied by large-scale software macro-topology, the software architectures were abstracted to be a network topology. Then, by the metrical analysis of complex network, the scale-free characteristic embodied by degree distribution in large-scale software macro-topology was discussed in two ways, i.e., the pdf-degree distribution in undirected graph and the pdf-degree distributions of in-degree and out-degree in directed graph. With the evolving software, both the degree distribution coefficient and in-degree distribution coefficient tend to decrease but the in-degree of maximum node tends to increase. However, the fluctuation of out-degree distribution coefficient and out-degree of maximum node are not obvious. The reasons why the degree distribution thus varies are discussed in association with the software engineering in practice, and it is therefore concluded that there is room for further optimization in the architecture of software system. References | Related Articles | Metrics

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On the new minimum interference routing algorithm (NMIRA) and its simulation Du, Li (1); Huang, Jun (1); Lin, Xiao (1) 2009, 30 (11):  1578-1581.  DOI: - Abstract ( 252 )   HTML   PDF (1179KB) ( 553 )   Based on the framework of offline phase in combination with online phase, a new minimum interference routing algorithm (NMIRA) was proposed to deal with different types of service requests. In the offline phase the pre-distributed bandwidth is implemented via optimizing the network to build the selectable path library for online routing phase, while in the online phase the critical links are selected using the shortest/narrowest routing algorithm to compute the link weight in accordance to the ratio of used bandwidths to usable bandwidths in various types of services, thus attaining the target of minimum interference with the algorithm complexity reduced. The simulation results of different network topologies showed that the algorithm proposed significantly improves the reject rate of requests and the total usable bandwidth. References | Related Articles | Metrics

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On the low-carbon plate steel E40-Z35 for offshore platform Di, Guo-Biao (1); Liu, Zhen-Yu (1); Liu, Xiang-Hua (1); Ma, Qing-Shen (2) 2009, 30 (11):  1582-1585.  DOI: - Abstract ( 252 )   HTML   PDF (324KB) ( 795 )   With TMCP (thermo-mechanical control process) parameters determined via hot simulation in lab, the plate steel E40-Z35 for offshore platform was developed and put into pilot-scale production. The results showed that the TMCP includes the characteristics as follows: low carbon content (about 0.08wt%) in microalloying composition design; Ca-spheroidization for MnS inclusions; heavy reduction during the hot-rolling process at high temperature and low speed; starting and finishing the rolling process in non-recrystallized zone at 900°C and 800°C respectively, with workpiece finally cooled at about 640°C; the work done for absorbing conventional and ageing impact acting on the products after hot rolling at -40°C is higher than 200 J; the area reduction along thickness is higher than 45%; high laminar tearing strength. All of these illustrates that the plate steel prepared meets the requirements of any classification societies for the use of offshore platforms. References | Related Articles | Metrics

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Preparation of NanoSiC-doped MgB2 bulk superconductor by rapid hot pressing process Qu, Bo (1); Xue, Cui-Ping (2); Sun, Xu-Dong (1) 2009, 30 (11):  1586-1589.  DOI: - Abstract ( 247 )   HTML   PDF (418KB) ( 672 )   Compact MgB2 bulks as superconductor were successfully prepared by rapid hot pressing process in high-purity flowing Ar protective atmosphere. Describes the rapid hot pressing-sintering process systematically, including such optimal process parameters as sintering temperature, holding time and mixture ratio of starting materials. Discusses the effects of nanoSiC doping on MgB2 bulk in detail, such as microstructure, XRD pattern analysis and critical current density (Jc). It's found that the compact MgB2 bulks can be prepared at 950°C held for 30 min under hot pressing conditions. With furnace cooling followed, where the 5wt% nanoSiC doping performs an important role in improving the superconductivity. Moreover, Jc can be over 106 A/cm2 in self-field if tested at 20 K and remains above 105 A/cm2 at 5 K with the field intensity up to 7 T. The fact shows that the practicability of the preparing process has been improved. References | Related Articles | Metrics

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Phase composition and mechanical properties of B4C-ZrB2-Al composites prepared by vacuum infiltration Lü, Peng (1); Yue, Xin-Yan (1); Yu, Liang (1); Ru, Hong-Qiang (1) 2009, 30 (11):  1590-1593+1597.  DOI: - Abstract ( 278 )   HTML   PDF (486KB) ( 803 )   B4C-ZrB2-Al composites were prepared by infiltrating aluminum into the porous B4C-ZrB2 presintered compacts in vacuum. The phase composition and mechanical properties of the composites were investigated. The results showed that the phase composition of the composites changes with increasing ZrB2 content, and their hardness increases first then decreases but, on the contrary, the flexural strength and fracture toughness decrease first then increase with increasing ZrB2 content. The reason why the fracture toughness increases is mainly the infiltration of ductile aluminum. The B4C-ZrB2-Al composite is mainly composed of the phases B4C, ZrB2 and Al if the content of ZrB2 is 35wt%, i.e., its mechanical properties are optimum: the porosity, hardness (HRA), flexural strength and fracture toughness are 1.06%, 82.2, 521.5 MPa and 8.6 MPa · m1/2, respectively. A number of tearing ridges and dimples are found morphologically on the fracture surface, which reveal that the failure of the composite is mainly due to the intergranular and transgranular fracture. References | Related Articles | Metrics

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On the microstructure and refining mechanism of ZL201 alloy prepared by near-liquidus casting in electromagnetic field Wang, Ping (1); Li, Xiao-Feng (1); Cui, Jian-Zhong (1) 2009, 30 (11):  1594-1597.  DOI: - Abstract ( 211 )   HTML   PDF (449KB) ( 645 )   With the casting temperature lowered properly and an electromagnetic field applied to the preparation of ZL201 alloy, the solidified structure and its refining mechanism were investigated. The results revealed that the alloy is of a homogeneous, fine and non-dentritic crystalline structure which tends to be finer and more homogeneous with the increasing current and enhanced cooling effect. When casting at near-liquidus temperature, the radius of critical crystal nucleus decreases and, meanwhile, the melt temperature gradient decreases under the action of electromagnetic field, thus stimulating the formation of quasi-solid radicals to increase nucleation rate and making the structure finer and more homogeneous. During the initial solidification the growth rates of crystal nuclei in diverse directions tend to the same with grains growing up in sphere-like shape, since the distribution of solutes becomes uniform under the action of electromagnetic field. References | Related Articles | Metrics

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Influence of ESR process parameters on solidification quality of remelting ingots Dong, Yan-Wu (1); Jiang, Zhou-Hua (1); Xiao, Zhi-Xin (1); Li, Zheng-Bang (2) 2009, 30 (11):  1598-1601.  DOI: - Abstract ( 333 )   HTML   PDF (364KB) ( 603 )   Based on the mathematical model developed previously by the authors for ESR process, the optimal process technologies were determined for some slag systems to be used in ESR process from which the steel will be provided for cold rolls. Analyzing the quality of remelting ingots, the influence of technological schedule on the solidification quality of those ingots was investigated. Testing results showed that the reasonable selection of process parameters is actually feasible to control local solidification time and secondary interdendritic spacing and, further, control the segregation in remelting ingots. With regard to the steel Cr5 for cold rolls, the longer the local solidification time, the longer the corresponding secondary interdendritic spacing and the higher the content of carbides due to segregated elements. References | Related Articles | Metrics

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OpenMP-based parallel numerical simulation of collision and aggregation among particles in turbulent field Lei, Hong (1); He, Ji-Cheng (1) 2009, 30 (11):  1602-1605.  DOI: - Abstract ( 332 )   HTML   PDF (932KB) ( 554 )   To speed up the simulation of the turbulence-collision-aggregation among 10, 000 particles, OpenMP is introduced to parallelize the FORTRAN source codes for Smoluchowski equation. Numerical results showed that if the serial program's structure remains unchanged and only the loops are parallelized, the parallel performance will be up to 80%, and the computational results of both parallel and serial programs coincide. For the heavy-load computation of loops, the computing time required is minimum if all CPUs are used, but for the light-load one, it is unsure whether the computing time required is minimum even if all CPUs are used. References | Related Articles | Metrics

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Influence of high-intensity magnetic field on substitution reaction rate on slag-metal interface Li, Yan-Hua (1); Su, Zhi-Jian (1); He, Ji-Cheng (1) 2009, 30 (11):  1606-1608.  DOI: - Abstract ( 309 )   HTML   PDF (260KB) ( 749 )   The rate of substitution reaction between the Al-Cu alloy and quaternary slag of which the mixture ratio in mass fraction is w(MgF2):w(CaF2):w(LiF):w(ZrF4) = 1.7:1:1.5:9.3 in the high-intensity magnetic fields under different conditions was investigated to make sure of how the high-intensity magnetic fields affect every and each step in the reaction process on slag-metal interface and the global reaction rate. The results revealed that the reaction rate is quickened owing to the micro-MHD effect if the high-intensity magnetic field applied to the reaction interface is of zero gradient, while the reaction rate changes in the high-intensity gradient magnetic field because the reaction interface is under the action of both the magnetizing force evoked by the magnetic field and micro-MHD effect. A conclusion is thus drawn that the reaction rate on slag-metal interface can be controlled efficiently via a high-intensity magnetic field. References | Related Articles | Metrics

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Research on modeling estimation of slag viscosities Dou, Zhi-He (1); Zhang, Ting-An (1); Niu, Li-Ping (1); He, Ji-Cheng (1) 2009, 30 (11):  1609-1612.  DOI: - Abstract ( 254 )   HTML   PDF (271KB) ( 620 )   Mere measurements can not meet the actual requirements for determining the slag viscosities. Based on the viscosity model and regular solution model for slag proposed by D Sichen and S Seetharaman, the functional relationship between the slag viscosity and composition and the Gibbs viscous activation energy and mixture free energy of slag components was derived, i.e., the viscosity estimation model. Then, the viscosities of both CaF2-CaO and Al2O3-CaO slag system samples were estimated and measured. The results indicated that, the estimated viscosities modified by the model and the measured ones coincide well for CaF2-Ca O slag system. As for the Al2O3-CaO slag system, the estimated viscosities conform basically with the measured ones but both coincide better in the vicinity of compositional eutectic point. References | Related Articles | Metrics

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Development and application of water-sprinkled cooling system to roller quenching machine Yuan, Guo (1); Wang, Zhao-Dong (1); Wang, Guo-Dong (1); Wang, Li-Jun (2) 2009, 30 (11):  1613-1616.  DOI: - Abstract ( 287 )   HTML   PDF (512KB) ( 677 )   According to the actual process parameters, the effect of different header inlets and flow deflectors on water flow distribution in the quenching machine was using the software FEM ANSYS. The results obtained through numerical simulation indicated that the header with middle water inlet can form the central convex water distribution to a certain extent along the deflector width so as to acquire the reasonable water flow distribution easier than terminal inlet. The damping effect due to flow deflectors in header can significantly improve the sprinkled flowrate distribution. Taking the slot nozzle we developed as an example, the flow properties of water jet in slot were analyzed. Simulation results revealed that the flowrate distribution of water jets from the slot nozzles is quite uniform with small turbulence, thus benefiting the homogeneity during cooling the plates being quenched. The water-sprinkled cooling system has been applied successfully to the roller quenching machine with its favorable performance proved. References | Related Articles | Metrics

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Application of whole process tracking to plate production line Jiao, Zhi-Jie (1); Wang, Jun (1); He, Chun-Yu (1); Li, Yong (1) 2009, 30 (11):  1617-1620.  DOI: - Abstract ( 354 )   HTML   PDF (770KB) ( 650 )   According to the plate production process and analysis of domestic actualities, the whole process tracking for the plate production line is divided into three parts: position micro-tracking, process tracking and material tracking, with a consolidated scheme determined to implement the tracking procedure. The position micro-tracking is put into effect by the basic automation system to provide the key tracking information, the process tracking and material tracking both depend on the process control system. With the data flow designed for the whole process tracking, a central database is set up for tracking data storage/transfer. Then, the material tracking is implemented according to the operation of data sheet. The whole process tracking proposed here has been applied successfully in several domestic plate production lines. References | Related Articles | Metrics

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Existing problems of gauge meter AGC in application and solutions Sun, Jie (1); Zhang, Dian-Hua (1); Li, Xu (1); Zhang, Ze-Rui (2) 2009, 30 (11):  1621-1623+1627.  DOI: - Abstract ( 332 )   HTML   PDF (422KB) ( 453 )   In-situ application indicated that the two important problems of AGC were found: the roll eccentricity results in wrong roll gap adjustment that is provided by the gauge meter AGC; there is mutual interference when the monitor AGC is also used simultaneously as a monitor. The two problems are discussed in detail via the combination of the principle of AGC with its actual applications. For the problem evoked by roll eccentricity, a filtering technique is introduced to filter off the disturbance due to roll eccentricity and provide correct roll gap adjustment effectively. For the problem of mutual interference evoked by using monitor AGC simultaneously, the correlation between the two adjustments obtained in different ways is processed to avoid repeated or opposite adjustments. Application results indicated that the problems are thus solved well to meet the requirement for thickness control precision. References | Related Articles | Metrics

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Application of workpiece head thickening method in plate rolling process Hu, Xian-Lei (1); Zhao, Zhong (1); Liu, Xiang-Hua (1) 2009, 30 (11):  1624-1627.  DOI: - Abstract ( 262 )   HTML   PDF (405KB) ( 544 )   Based on the analysis of the change in torque during plate rolling with respect to each pass reduction, it is known that the peak torque occurring in the biting phase of workpiece head is the key factor to restrain the pass reduction. In view of how the steady-state rolling torque changes in the whole rolling process, the workpiece head thickening method is proposed for the early pass reductions in both spread and elongation rolling phases, i.e., the pass reduction is increased properly during steady-state rolling after the biting phase. Then a relational expression of rolling torque and pass reduction is derived, by which the reduction is given. The method proposed can effectively improve the capacity of rolling mills without reform the existing rolling system. It is therefore applicable to plate mills. References | Related Articles | Metrics

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Stability of synchronous operation of vibrating system driven by two motors Wang, De-Gang (1); Zhao, Qing-Hua (2); Zhao, Chun-Yu (1); Wen, Bang-Chun (1) 2009, 30 (11):  1628-1631.  DOI: - Abstract ( 213 )   HTML   PDF (2409KB) ( 441 )   To investigate the stability of synchronous operation of a vibrating system driven by two motors, a dynamic model is developed for the system that was analyzed nonlinearly and dynamically. Making the parameters of the system dimensionless, the frequency trapping equations of the vibrating system and the conditions for implementing stable self-synchronous operation are both obtained, thus computing the stability region of self-synchronous operation. Then, the design of such a vibrating system is optimized on the basis of the conditions and stability region as above so as to readjust the parameters of the vibrating system. The simulation results showed that the synchronization of vibrating system comes true in either speed or phase to enable the system to be in a good self-synchronous state. The correctness of the conditions for stability and stability region of self-synchronous operation and the effectiveness of the optimized design are therefore verified. References | Related Articles | Metrics

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Parameterized modeling for visual optimization design of mechanical products Sun, Wei (1); Ma, Hui (1); Li, Chao-Feng (1); Wen, Bang-Chuan (1) 2009, 30 (11):  1632-1635.  DOI: - Abstract ( 259 )   HTML   PDF (653KB) ( 665 )   Visual optimization design (VOD) is a sort of modern design method based on three-dimensional model. The modeling speed affects the research efficiency of VOD directly, and it was found that the parameterized modeling can develop the model rapidly due to parameter drive which will serve VOD well. The method of parameterized modeling is proposed for VOD of mechanical products. Analyzing the relation between parameterized modeling and VOD, the general procedure to implement parameterized modeling is proposed including such crucial steps as determining functional modules, analyzing parameters, parameterizing the modeling process of different parts and assembling auto control system. With a 3-PPT parallel kinematics machine tool taken for testing, on which a parameterized modeling system is developed using the software VB on the SolidWorks as platform, thus verifying the validity of the method proposed. References | Related Articles | Metrics

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Assembly sequence planning based on screening of priority rules Yu, Jia-Peng (1); Wang, Cheng-En (2); Zhang, Wen-Lei (2); Yu, Hong (1) 2009, 30 (11):  1636-1640.  DOI: - Abstract ( 306 )   HTML   PDF (771KB) ( 1184 )   Aiming at the deficiency and inaccuracy in multi-objective optimization for assembly sequence planning, a novel assembly model and optimization algorithm is proposed. A more compact contact-connection matrix is constructed to provide more information in relation to assembly, and an extended interference matrix is given to solve the assembly problems in non-orthogonal direction to which other existing methods are unable. The methods for automatically acquiring the matricies are also studied. Several rules that affect assembly efficiency are studied from the viewpoints of automatic planning and quantification, with the flexibility provided for customizing them and their priorities. Then, an optimization algorithm is proposed via screening out the information as above stepwise so as to form a wholly optimized sequence. A prototype system is developed on UG platform with a valve taken as example to verify the feasibility and effectiveness of the method proposed, as well as its good visualized simulation effect. References | Related Articles | Metrics

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Reliability-based optimization design of vehicle parts by saddlepoint approximation Jin, Ya-Juan (1); Zhang, Yi-Min (1); Zhang, Yan-Lin (1); Wang, Xin-Gang (1) 2009, 30 (11):  1641-1644.  DOI: - Abstract ( 291 )   HTML   PDF (320KB) ( 556 )   Combining the reliability theory with optimization technique, the reliability-based optimization design for vehicle parts is emphatically discussed, then a numerical method is proposed for the reliability-based optimization design. Based on the premise that the probability distribution of random parameters has been known, the probability density function and probability distribution function of random structural response under external loading are accurately and quickly obtained by way of saddlepoint approximation and, as a result, the saddlepoint approximation method is proved accurate with higher computing speed in comparison with the Monte-Carlo method. Therefore, the reliability of vehicle parts computed by the saddlepoint approximation lays a theoretical foundation for the reliability-based optimization of vehicle parts, and it can accurately and quickly acquire the design information. References | Related Articles | Metrics

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PD control of swiveling jib system of concrete delivery truck Dai, Li (1); Wang, Jian (1); Liu, Yu (1); Liu, Jie (1) 2009, 30 (11):  1645-1648.  DOI: - Abstract ( 252 )   HTML   PDF (463KB) ( 725 )   Based on the multi-body dynamic theory, the movement of every member of the swiveling jib and relevant hydraulic cylinders on a concrete delivery truck are both analyzed. With the Lagrange equation, the multi-body dynamic equation of the swiveling jib system is derived. A control model is then developed for the swiveling jib system via applying the PD control rate to every member's drive torque so as to enable it to move in accordance to the expected rotating angles. Further, based on the multi-body dynamic equation of swiveling jib system as above, a dynamic equation of the integrated jib truck system is built with a numerical solution given to it, thus analyzing comparatively the calculated and expected values of both rotating angle of each member of swiveling jib and the kinematic trajectory of its end. It is proved that the integrated dynamic equation thus built can exactly describe all the dynamic characteristics of the truck. References | Related Articles | Metrics

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Research and simulation of hydraulic excavator's adaptive fuzzy sliding control Liu, Kuo (1); Guo, Da-Meng (1); Liu, Jie (1); Yang, Ke-Shi (1) 2009, 30 (11):  1649-1652.  DOI: - Abstract ( 312 )   HTML   PDF (263KB) ( 1030 )   To eliminate the chattering in sliding control, a structure-variable controller is developed for adaptive fuzzy sliding. Introducing the adaptive fuzzy control to continuously approximate to the equivalent controller so as to make the equivalent control independent of the accurate mathematic model of the hydraulic excavator's bucket, the robustness of the uncertainty control system is enhanced and then applied to the trajectory tracking control of the hydraulic excavator's bucket. The control law involves three parts, i.e., the equivalent, switching and regulating control. The adaptive fuzzy sliding control is simulated with Matlab7.4/Simulink for path tracing of excavator's bucket, thus revealing the tracking performance and input control. References | Related Articles | Metrics

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Digital analysis and design of crankshaft of a reciprocating compressor Chen, Peng-Fei (1); Sun, Zhi-Li (1); Teng, Yun-Nan (1) 2009, 30 (11):  1653-1656.  DOI: - Abstract ( 280 )   HTML   PDF (1850KB) ( 692 )   To improve the design of a reciprocating compressor, the Visual C++ and Pro/E were used to develop a system software for the digital analysis and design of crankshaft. The stress state of crankshaft was analyzed during a cycle period on the principle of both thermodynamics and dynamics. A limit-state equation was given for the critical sections according to the randomness of design parameters, such as geometric dimensions, machining process and material strength. Then, both the reliability of fatigue strength and the sensitivity of influencing parameters were discussed so as to implement the digital analysis via VC. And all the design parameters of the crankshaft, including dimensions, process technology and material, were thus determined to implement the digital design via Pro/E. The results showed that the digital system software combining reliability theory with modern computer technology is highly promising in engineering practice. References | Related Articles | Metrics

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Evaluation and optimization of urban land supply efficiency in Shenyang Qi, Xi-Jing (1); Dai, Zi-Long (2); Deng, Li-Jie (3); Hu, Nai-Long (1) 2009, 30 (11):  1657-1661.  DOI: - Abstract ( 203 )   HTML   PDF (1130KB) ( 749 )   To optimize the allocation of resources and make the economic development especially the real estate sustainable in Shenyang, such existing problems as the gross area of urban land oversupplied and imbalance spatial allocation with imperfect structure have to be solved. Based on the data from 2002 to 2006 and taking the area of land supplied and investments in fixed assets as input units, with land-grant fee and GDP as output units, the DEA (data envelopment analysis) or C2R model was made to evaluate the overall efficiency and the efficiency of space/usage structure of land supply in accordance to an example, then the values of input redundancy and output deficiency of unit index in decision making were calculated. Furthermore, some suggestions were therefore offered about the improvement based on projection theory for the non-DEA effective years, thus realizing the benefit prediction after improvement. The method mentioned above will be of importance to the evaluation of urban. References | Related Articles | Metrics

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High-viscosity petrochemical wastewater treatment with polymerized silicon-phosphorus ferric sulfate as flocculant Xu, Xin-Yang (1); Li, Li-Jun (2); Li, Ru (1) 2009, 30 (11):  1662-1665.  DOI: - Abstract ( 333 )   HTML   PDF (300KB) ( 430 )   A new flocculant named polymerized silicon-phosphorus ferric sulfate was developed in lab to treat high-viscosity petrochemical wastewater in a plant of Liaohe Pertrochemical Corporation. The results showed that its optimal treating parameters are as follows: mass concentration 200 mg/L, pH value 6~9, temperature range 25~45°C, stirring time 2 min and sedimentating time 3 min. Under such conditions, a series of comparison tests were done between the newly-developed flocculant and currently-used one during wastewater treatment in the plant, and the comparison results showed that the former can remove 94.1% oil, 69.4% COD, 88.9% sulfide and 43.5% volatile phenol, i.e., much higher than the latter of which the corresponding removing rates are 80.5%, 35.8%, 21.1% and 17.3%, respectively. References | Related Articles | Metrics

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On the contrast research between carboniferous coral reefs in Southern Guizhou and modern coral reefs in South China Sea Chang, Hong-Lun (1); Gong, En-Pu (1); Guan, Chang-Qing (1); Yang, Li-Li (2) 2009, 30 (11):  1666-1669.  DOI: - Abstract ( 374 )   HTML   PDF (664KB) ( 867 )   Contrast between the carboniferous coral reefs in Southern Guizhou and modern coral reefs in South China Sea was done in view of their formation processes and division of sedimentary facies belts, based on the sedimentary environment and characteristics of coal reef. The results showed that a lot of inhabitants are filled in the coral reefs in Bianping village, such as Fusulinids, clum of encrinite and fragments of brachiopod, while the coral fragments are dominantly filled in the modern coral reefs. The fact reveals that although the two reefs are formed in different ages, they are similar in the distribution of sedimentary facies belts and reef formation process, which closely relates to the reef community's status. Compared with the tetra-coral in Late-Carboniferous, the modern hexacoral is more adaptive to environment, and the formation process of modern coral reefs is more labyrinthian. References | Related Articles | Metrics

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Theoretical calculations for phase transition of MgAl2O4 spinel under high pressure Li, Mei-Ling (1); Zhang, Qian-Yu (1); Sun, Feng-Jiu (1) 2009, 30 (11):  1670-1672.  DOI: - Abstract ( 301 )   HTML   PDF (311KB) ( 714 )   The equations of state, thermodynamically formed enthalpy and mechanic properties of the three phases of MgAl2O4 oxides under 50 GPa were presented via the pseudowaves plane (PWP) approach based on density functional theory (DFT). The calculated results showed that according to the state equations the transition pressures under which the MgAl2O4 spinel was transformed into CaFe2O4-type MgAl2O4 CF-phase and then into CaTi2O4-type MgAl2O4 CT-phase are 26.79 GPa and 30.19 GPa, respectively, and the differences between the calculated and tested values are +0.79 GPa and -11.81 GPa, respectively. With the thermodynamically formed enthalpy in combination with GGA, the CF-phase transition pressure is 24.52 GPa, while the CT-phase transition pressure is 39.85 GPa if combined with LDA, i.e., the comparative errors are -1.48 GPa and -2.15 GPa, respectively. It was found that the mechanical structure of spinel are unstable under the pressure over 30 GPa. But, in case the spinel phase is under the other two high pressures as above, its mechanical properties are stable if the pressures are in the range that has already been taken into account. References | Related Articles | Metrics