Archive

15 October 2005, Volume 26 Issue 10 Previous Issue    Next Issue
---
OriginalPaper


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

OriginalPaper

Select

Nonlinear robust backstepping design of STATCOM using neural networks Liu, En-Dong (1); Jing, Yuan-Wei (1); Wang, Ke (2); Zhang, Si-Ying (1) 2005, 26 (10):  919-922.  DOI: - Abstract ( 343 )   HTML   PDF (1317KB) ( 502 )   A novel backstepping control technique based neural networks is presented for single machine infinite bus system with STATCOM to design a nonlinear controller. Motivated by the well-known backstepping design technique, the method is systematic and robust to parameter variation. The controller derived can guarantee the boundedness to both tracking error and weight updates. No prior knowledge of the upper bound on the optimal weight values is required. The weights of neural networks are updating on-line, and the off-line training phase is not required. Numerical simulation was carried out to illustrate and clarify the approach. References | Related Articles | Metrics

Select

Robust stability of a class of interval switched systems Zhao, Sheng-Zhi (1); Li, Jian-Hua (1); Zhao, Jun (1) 2005, 26 (10):  923-925.  DOI: - Abstract ( 199 )   HTML   PDF (1451KB) ( 931 )   Discusses the robust stability of a class of interval switched systems with parameter uncertainties. As a switched system, its robust stability depends on the stability of nominal system. Making full use of such structural properties, the robust stability of an interval switched system can be derived from the stability of its nominal system. When all subsystems of a nominal system are asymptotically stable, the conditions on which the robust stability of relevant interval switched system can be achieved for all switching laws are given. Furthermore, using the convex combination technique, the robust stability of an interval switched system is obtained under a certain switching law if no subsystem of nominal system is asymptotically stable. References | Related Articles | Metrics

Select

Feedback-linearized control of a class of population growth models Zhang, Yue (1); Zhang, Qing-Ling (1); Zhao, Li-Chun (2); Liu, Pei-Yong (1) 2005, 26 (10):  926-929.  DOI: - Abstract ( 231 )   HTML   PDF (380KB) ( 593 )   Discusses the problem of the chaotic control of a class of population growth models with time lag. Computing the Lyapunov exponents and Lyapunov dimension of the system, the fact that there is a chaos phenomenon in the population growth models with time lag is verified. A feedback controller is designed to capture or release adult population by feedback linearization as to stabilize the chaotic orbits and enable them to be ideal target ones, i.e., unstable fixed points of the chaotic system. The unstable population system will therefore become stable by a rational development policy. Numerical simulations indicate that this feedback controller is effective in practice. It will cause the biological population in chaos states to stabilize and come into an ideal state, thus realizing orderly existence with balance of nature maintained for long. References | Related Articles | Metrics

Select

Optimized power supply model in melting period of SR-EAF Yuan, Ping (1); Wang, Fu-Li (2); Mao, Zhi-Zhong (2) 2005, 26 (10):  930-933.  DOI: - Abstract ( 247 )   HTML   PDF (321KB) ( 614 )   Analyzing the electric characteristics of the melting period of supplemental reactor electric arc furnace (SR-EAF), an optimized power supply model is established on the basis of mixed-integer nonlinear programming (MINLP) model to minimize the power-on period and electric power consumption. The influences of the supplemental reactor, the output voltage of transformer and Arc Beam Index (ABI) on the power supply strategy are fully considered in this model where the current of electric arc, value of supplemental reactor and service voltage are all optimized. The power-on strategy decided by such an optimized model is proved better than that only by Maximum-Arc-Current method or Economic-Current method in practice. The optimized power supply model improves not only the power supply efficiency but the economic benefits in steel-making by SR-EAF. References | Related Articles | Metrics

Select

R&D of multimedia software for industrial process monitoring systems Gao, Xian-Wen (1); Yang, Jun (1); Yu, Xiao-Feng (1) 2005, 26 (10):  934-937.  DOI: - Abstract ( 213 )   HTML   PDF (248KB) ( 560 )   To meet the application requirements of domestic industrial enterprises, the multimedia architecture of industrial process monitoring system and the principle of design of relevant hardwares and softwares are discussed in detail, as well as the selection of the way to compress the data of the monitoring system and the audio/video compression standard. Combining the R&D of softwares with the actual requirements for the Multimedia Production Process Monitoring Network System in Jiuquan Steel Group, such software developing and programming techniques as the secondarily developed MPEG-1 hardware compression/decompression monitoring card with SDK and Winsock and Directshow programming are all used. As a result, the multimedia monitoring softwares are successfully developed to serve the necessary functions for industrial process information, such as recording, playback and transmission. References | Related Articles | Metrics

Select

Branch-and-bound algorithm for scheduling on single processor with sequence-dependent setup times to minimize maximum tardiness Luo, Xiao-Chuan (1); Liu, Chang-Yong (1); Liu, Xiao (2); Wang, Cheng-En (1) 2005, 26 (10):  938-941.  DOI: - Abstract ( 244 )   HTML   PDF (174KB) ( 673 )   The NP-hard problem of scheduling N jobs on a single processor with due dates and sequence-dependent setup times is studied, where the objective is to minimize the maximum tardiness. By relaxing the connectivity constraints to eliminate subtours the lower bound methods are proposed. Then, the upper bound methods are constructed by the modified Karp-Steel patching heuristic method based on the solution of lower bound problem. Two dominance rules are proved according to the natural features of the problem. An algorithm based on Ragatz's branch-and-bound permutation schemes is thus developed including the implementation of lower and upper bounding procedures and dominance rules. Computational experiments demonstrate the effectiveness of the algorithm. References | Related Articles | Metrics

Select

Casting speed optimization control system based on continuous temperature measurement of molten steel in CC tundish Meng, Hong-Ji (1); Wu, Rong-Yang (1); Xie, Zhi (1); Lin, Guo-Qiang (2) 2005, 26 (10):  942-945.  DOI: - Abstract ( 213 )   HTML   PDF (261KB) ( 439 )   To improve the output and quality of products in casting, the existing manual speed control for billet caster with molten steel level in mold controlled by stopper was investigated. A feed forward control system was thus designed according to the optimal relationship between casting speed and superheat which was obtained from the casting speed optimization control model that developed on the basis of the heat transfer model and production practice, with the restriction on maximum casting speed and shell thickness at mold exit involved. Furthermore, a hierarchical control system was designed where the casting speed changes with superheat. The reliability of changeover of the control modes switched was discussed emphatically. Field application shows that the proposed control system runs robustly and reliably and satisfies the production requirements. References | Related Articles | Metrics

Select

Simulating estimate based on neural network for friction factor in dynamic rolling process Li, Shen (1); Hou, Xiang-Lin (2); Yuan, Yan-Li (3); Yu, He-Ji (1) 2005, 26 (10):  946-948.  DOI: - Abstract ( 191 )   HTML   PDF (136KB) ( 455 )   Based on feed forward multi-layer artificial neural network, a new way to estimate the friction factor between roller and workpiece was studied. The factor was taken as a multi-variable non-linear function which was affected jointly by such independent parameters as rolling temperature, lubricant viscosity and rolling speed. The nonlinear mapping of artificial neural network was used to construct a complicated mathematical model in terms of dynamic friction factor and influencing parameters. An interpolation-approximation method based on ANN was proposed and programmed to estimate the working friction factor in rolling process, with a simulation done as an example. The results showed that the new method provides a means available to control and stabilize effectively the rolling process without slippage and prevent it from unbalanced load. References | Related Articles | Metrics

Select

Implementation of adaptive genetic algorithm of evaluation function in Chinese chess computer game system Wang, Jiao (1); Wang, Tao (1); Luo, Yan-Hong (1); Xu, Xin-He (1) 2005, 26 (10):  949-952.  DOI: - Abstract ( 288 )   HTML   PDF (160KB) ( 1677 )   Adaptive Genetic Algorithm (AGA) is used to solve the problem of Chinese chess game on computer. The game system is divided into four parts: searching engine, move generator, evaluation function, and opening book. Then, the AGA is brought into evaluation function to automatically adjust and optimize the parameters' combination of evaluation function by tournament algorithm. Based on the above methods, an off-time self-study system is designed. The experiment results show that the AGA improves the performance of the program developed. References | Related Articles | Metrics

Select

Model and algorithm to optimize location of catastrophic rescue center Wang, Ding-Wei (1); Zhang, Guo-Xiang (1) 2005, 26 (10):  953-956.  DOI: - Abstract ( 231 )   HTML   PDF (189KB) ( 910 )   Proposes a mathematical model to optimize the location of catastrophic rescue center, taking account of the probability of catastrophic occurrence, catastrophic diffusion function and rescue function. Because the catastrophic diffusion and rescue functions are both nonlinear and time-variable, they are very difficult to be solved by way of common mathematical programming. A heuristic embedded genetic algorithm is therefore developed to solve the special model. The computation of a large number of examples arising from practice provide satisfactory results. References | Related Articles | Metrics

Select

Online measurement of workpiece length based on image processing techniques Sha, Yi (1); Cao, Ying-Yu (1); Wang, Jing-Wu (2); Sheng, Guo-Song (3) 2005, 26 (10):  957-959.  DOI: - Abstract ( 338 )   HTML   PDF (221KB) ( 1186 )   Aiming at a conveyer line of heated ingots in a roll mill, a method is presented for online measurement of workpiece length. The image information of a workpiece on a production line is acquired by a CCD camera at distance, and then the edge noise of the image is filtered. The real-time measurement is carried out using a simple algorithm or the gradient operator of image grey scale to detect and recognize quickly the edge of an image, thus acquiring the workpiece length. The quadratic polynomial is fitted to compensate the non-linearity of the camera lens so as to improve the measuring precision. Introduces the structure and functions of a real-time system for online measurement and analyzes its speed and precision. The results show that when the workpiece length is 400-1200 mm with conveying speed less than 5 m/s, the measuring error is lower than 0.4%. References | Related Articles | Metrics

Select

Query optimization based on site constraints in PDMS Wang, Bin (1); Yang, Xiao-Chun (1); Wang, Guo-Ren (1); Zhang, En-De (1) 2005, 26 (10):  960-963.  DOI: - Abstract ( 223 )   HTML   PDF (161KB) ( 445 )   Query rewriting technique based on views is an important solution to sharing data in PDMS (peer data management system). An extended Datalog technique based on peer constraints is proposed to optimize query processing in PDMS. In particular, the query optimization problem in data-intension and logical tight-coupled PDMS environment is studied. The definition language for PDMS views, PView and the definitions of local and global peer constraints are proposed, as well as the query rewriting optimization algorithms. A cost model is given to evaluate-the queries in PDMS. Experimental results show that the proposed approach outperforms other view-based query rewriting approaches. References | Related Articles | Metrics

Select

Effectiveness evaluation model for air-to-ground attack Chen, Dong-Ming (1); Zhu, Zhi-Liang (1); Chang, Gui-Ran (2); Gao, Xiao-Xing (1) 2005, 26 (10):  964-967.  DOI: - Abstract ( 203 )   HTML   PDF (117KB) ( 951 )   Air-to-ground attack is a kind of the most powerful combat operations. For the battle efficiency analysis of weapon systems, the combat simulation plays a most important role in military drill. Only after analyzing and evaluating the attack results and modifying relevant firing data can an attack plan get better effect. A mathematical model of air-to-ground attack was thus developed, with which the accessible zone, probability of first attack destruction, rate of target recognition and CEP were derived. Results of testing bombing practice showed that the model is accurate and effective. It can improve the efficiency of military drill, save expenses of national defence greatly and is available to apply widely in engineering practice. References | Related Articles | Metrics

Select

Texture and microstructure of warm-rolled Ti-IF and Ti+Nb-IF steel sheets Zhang, Jin-Gang (1); Jiang, Qi-Wu (2); Liu, Yan-Dong (1); Zuo, Liang (1) 2005, 26 (10):  968-971.  DOI: - Abstract ( 239 )   HTML   PDF (204KB) ( 737 )   The microstructure and texture characteristics of warm-rolled Ti-IF steel sheets and Ti+Nb-IF steel sheets were investigated. The results of optically metallographic observation, morphology analysis of dispersed second phase particles and texture analysis showed that the grain size and the size and quantity of second phase particles of Ti-IF steel sheets are all greater than that of Ti+Nb-IF steel sheets. In the surface layer, the texture intensity of these two steel sheets are quite different. But in the middle layer, cold rolled texture component appears in both steel sheets. The fibre texture components are (1 1 0)//ND, (1 0 2)//ND in surface layer, and (0 0 1)//ND, (1 1 1)//ND and (1 1 2)//ND in middle layer. The <0 0 1>//RD and <1 0 2>//RD appear in the surface and middle layers of Ti-IF steel sheet samples respectively, which is different from Ti+Nb-IF steel sheets. References | Related Articles | Metrics

Select

Interaction among solute atoms and edge dislocations in steel or iron Zhang, Guo-Ying (1); Liu, Chun-Ming (1); Zhang, Hui (2); Zhao, Zi-Fu (2) 2005, 26 (10):  972-974.  DOI: - Abstract ( 281 )   HTML   PDF (134KB) ( 611 )   The atomic structure model of 1/2 [1 1 1] edge dislocation in ferrite phase of steel or iron was set up with computation programmed. The environment-sensitive embedding energy (ESE) and total structure energy of C, N and other alloy elements in grains or in dislocation area were calculated by recursive method separately. The aggregation of and interaction among C, N and alloy elements in dislocation area were discussed. Calculation results showed that the light impurities C and N tend to aggregate at the core of edge dislocation and all the edge dislocations are tied together and can not move freely. The elements Ti, V, Nb and Cr, are formed by strong or moderate carbides and easy to aggregate on the edge dislocation line, but Ni, as not formed by carbides, aggregates in the elastic expansion area below the dislocation line. The light impurities aggravate the aggregation of the elements formed by strong carbides on the edge dislocation lines. Thus, when lowering the temperature the concentrations of C and N and alloy elements exceed the solid solubility limit, and the C and N intermetallic compounds precipitate in the edge dislocation area of ferrite in steel or iron. These compounds will retard the movement of dislocations to cause the strengthening of steel or iron. References | Related Articles | Metrics

Select

New quadratic curve method to calculate temperature distribution of hot-rolled strips during cooling control Han, Bin (1); Zhou, Cun-Long (2); Wang, Guo-Dong (1); Liu, Xiang-Hua (1) 2005, 26 (10):  975-978.  DOI: - Abstract ( 252 )   HTML   PDF (164KB) ( 462 )   Considering that the thermal-conductivity coefficient is a linear function of temperature, a temperature distribution equations is derived from the 1-D heat conduction equation to characterize the concave/convex form of a quadratic curve. A conclusion is thus drawn that the concave/convex form of the quadratic curve depends on the changing tendency of the temperature-dependent thermal-conductivity coefficient. Then, the transition relation between the surface temperature and mean temperature is provided to relation solve the problem that the result using the conventional quadratic equation in concave form to calculate the temperature distribution in thickness direction with approximate fitting technique is different from that using the same equation in convex form for thick hot-rolled strips during cooling control after rolling. Such a transition relation has been applied to the model of online coiling temperature control and proved available to improve its accuracy. References | Related Articles | Metrics

Select

Rolling technology of fine-grain grade III bars with plain carbon steel Wang, Xiao-Wen (1); Zhao, De-Wen (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2005, 26 (10):  979-981.  DOI: - Abstract ( 203 )   HTML   PDF (414KB) ( 593 )   400 MPa hot-rolled ribbed bars in diameters from 6 mm to 10 mm were produced with plain carbon steel through controlled rolling and controlled cooling adjusting the billets' chemical composition. The technological investigation showed that it is fully attainable to produce Grade III bars meeting the National Standard GB1499-98 with plain carbon steel through comprehensive strengthening without adding any microalloy in the billets. The Grade III ribbed bars have been successfully produced up to over 3100 ton in steelworks in China using technology proposed. References | Related Articles | Metrics

Select

FEM analysis to the slab corner metal flow condition during multi-pass V-H rolling process Yu, Hai-Liang (1); Liu, Xiang-Hua (1); Li, Chang-Sheng (1) 2005, 26 (10):  982-985.  DOI: - Abstract ( 210 )   HTML   PDF (256KB) ( 571 )   The multi-pass vertical-horizontal (V-H) rolling process using plain-barreled edging roll and two grooved edging rolls with inward chamfer radius R=50 mm and R=80 mm was modeled by way of explicit dynamic FEM and updated geometries, and the slab corner metal flow under the conditions as above was analyzed. With the specified rolling schedule, it was found that the slab corner metal is curling and overturning onto the slab top surface when using the plain-barreled edging roll, and the slab corner metal is kept onto the line intersecting the top surface with side surface of the slab when using grooved edging roll. References | Related Articles | Metrics

Select

Fuzzy decision on reheating furnace temperature available to hold for rolling Zhang, Wei-Jun (1) 2005, 26 (10):  986-989.  DOI: - Abstract ( 203 )   HTML   PDF (933KB) ( 476 )   Based on the analysis of controlled characteristics of the dynamic process of reheating furnace, the mathematical model, fuzzy control theory and fuzzy optimization are used to investigate the dynamic process, temperature optimization and control of reheating furnace. A fuzzy model is developed to optimize the furnace temperature available to hold for rolling and an on-line fuzzy control decision system is set up on the basis of slab's heat conduction mechanism model. Then, a furnace temperature control decision can be made for typical temperature holding process for further rolling by numerical simulation. The results show that the temperature of slabs in furnace can thus be controlled satisfactorily and the model developed is proved effectively for reheating furnace control system. References | Related Articles | Metrics

Select

Characteristics of bending-torsional coupled vibrations of gear shafting Song, Xue-Ping (1); Yu, Tao (1); Li, Guo-Ping (1); Wen, Bang-Chun (1) 2005, 26 (10):  990-993.  DOI: - Abstract ( 226 )   HTML   PDF (280KB) ( 1452 )   Combining with rotor dynamics, a finite element model is developed for the gear-rotor system of a heavy-duty air compressor set with the elastic deformation of shaft, bearing and time-varying meshing stiffness taken into account. The characteristics of the bending-torsional coupled vibrations are therefore analyzed comprehensively for the gear-rotor system. Because the influencing factors on the system are too much, only such factors as the flexible diaphragm coupling, meshing stiffness, bearing stiffness arid bearing damping whether affects the natural frequency and stability of the gear-rotor system are discussed. The results showed that the meshing stiffness affects slightly the critical speed of the system but affects obviously the stability if the system is in a higher order mode. The mass of the shafts within the diaphragm coupling, number and thickness of diaphragms and the bearing stiffness and the damping all affect the critical speed and stability of the system to a certain extent. References | Related Articles | Metrics

Select

New method of structural synthesis based on screw theory for 3-DOF parallel robot mechanisms Luo, Ji-Man (1); Cai, Guang-Qi (1); Yang, Bin-Jiu (1); Zhao, Liang (1) 2005, 26 (10):  994-997.  DOI: - Abstract ( 255 )   HTML   PDF (159KB) ( 1146 )   The configuration design or the structural synthesis is the key factor in parallel robot designs. A new method to synthesize the 3-DOF parallel mechanisms called the constraint accession is proposed according to the screw theory in view of the classification of kinematical chains, where the active kinematical chains control the necessary DOFs and the passive kinematical chains control the unnecessary ones. The relevant active and passive kinematical chains are put forward and the constraint chains are classified in detail. It is demonstrated by an example that new configurations can be obtained by assembling different kinematical limbs. The new method makes the procedure of configuration design simpler and easier. As long as the number of the active chains chosen is the same to that of DOFs and the corresponding constraint chains are chosen reasonably, some new types of PRM can be assembled. References | Related Articles | Metrics

Select

Postprocessing algorithms based on 3-TPS hybrid machine tool Shi, Hong (1); Zhao, Liang (1); Cai, Guang-Qi (1) 2005, 26 (10):  998-1001.  DOI: - Abstract ( 198 )   HTML   PDF (169KB) ( 436 )   A new horizontal-vertical conversion hybrid machine tool, 3-TPS hybrid machine tool is introduced with its configuration analyzed. The hybrid machine tool not only has such advantages as large workspace, horizontal-vertical conversion, simultaneous motion of five axes and five-sides machining, but also serves the function of machining center. The coordinate transformation process and transformation equations of 3/4-DOF machining operation are given, as well as the postprocessing algorithms and mathematical model established for the implementation of such operation. Analyzing both the horizontal and vertical machining processes, the computational algorithms and equations are given in explicit forms. References | Related Articles | Metrics

Select

Real-time detection and track of moving image in intelligent vehicle driving system Yang, Ying (1); Zhao, Guang-Yao (1); Wu, Hua-Dong (1) 2005, 26 (10):  1002-1005.  DOI: - Abstract ( 241 )   HTML   PDF (374KB) ( 1051 )   Discusses an algorithm of moving object detection on the basis of algorithmic feasibility and demonstrates how to realize the real-time motional object detection. The algorithm detects the changing or moving images by difference method with the image background rebuilt. Then combining the continual characteristics of a motional figure array timely and contentedly, the algorithm sets up the historical records of motional foreground images. Processing further the images, the motional direction and speed of objects are calculated to realize the marking and segmented track of motional region. In addition, this algorithm is also suitable for the multiple occurring sometimes. It lays a sound foundation for image follow-up processing and pattern recognition in video technology with high robustness. References | Related Articles | Metrics

Select

Influence of heterogeneity on back analysis results of stress field in rock mass Zhu, Fu-Sheng (1); Du, Xuan (1); Wan, Ming-Fu (2) 2005, 26 (10):  1006-1008.  DOI: - Abstract ( 208 )   HTML   PDF (137KB) ( 439 )   Based on the assumption that the rock mass is of elastic medium and the mechanic model of continuous medium equivalent to jointed rock mass, the equivalent and statistically equivalent models of jointed rock mass are used to discuss the elastic modulus and the stress field in parent rock, both are computed inversely through the back FEM analysis of displacement. By back parametric analysis, the influences of the joint of rock mass and heterogeneity on the results of back analysis of displacement are further discussed. A conclusion is thus drawn that if the mechanic model of continuous medium equivalent to jointed rock mass is based on assumption, using different mechanic models has comparatively obvious influence on the elastic modulus computed inversely. While the heterogeneity of mechanic parameters of jointed rock mass has slight influence on the inversely computed stress field in parent rock. It implies that the assumption of homogeneity or isotropy is applicable to measuring the stress field in parent rock and back analysis of displacement. References | Related Articles | Metrics

Select

Nonlinear full-range analysis of concrete beam reinforced with FRP rods Zhang, Hai-Xia (1); Zhu, Fu-Sheng (1) 2005, 26 (10):  1009-1012.  DOI: - Abstract ( 201 )   HTML   PDF (915KB) ( 713 )   According to the mechanical behavior of concrete beam reinforced with FRP rods and numerical integration a calculation program is given taking account of the properties of materials used. The moment-curvature and loading-displacement relationships of the beam are thus obtained then compared with experimental results with a goodness of fit shown. Discussing the properties of the two relationships in different loading phases, they are divided into pre-cracking and post-cracking segments of beam section. The effects of percentage of reinforcement and concrete strength on moment-curvature curve are analyzed and show that the effect of former in pre-cracking is much less than that in post-cracking. The higher the percentage of reinforcement, the greater slope of curve, section stiffness and flexural strength of beam. At the same time, the higher concrete strength, the greater the cracking-moment and ultimate-moment on the beam section. References | Related Articles | Metrics

Select

- - 2005, 26 (10):  1013-1016.  DOI: - Abstract ( 190 )   HTML   PDF (158KB) ( 1121 )   - References | Related Articles | Metrics

Select

- - 2005, 26 (10):  1017-1020.  DOI: - Abstract ( 118 )   HTML   PDF (303KB) ( 681 )   - References | Related Articles | Metrics