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Robust controller design of uncertain multi-delay switched hybrid systems Yang, De-Dong (1); Zhang, Hua-Guang (1) 2007, 28 (9):  1217-1220.  DOI: - Abstract ( 257 )   HTML   PDF (1181KB) ( 600 )   The problem of robustly asymptotic stability for a class of uncertain multi-delay switched hybrid systems is discussed on the arbitrarily switched condition. The sufficient condition that such a system can keep up its robustly asymptotic stability if the L2 gain is given is put forward, which is described by linear matrix inequality. The robust stabilization problem of switched hybrid system is studied by using common Lyapunov function and the state feedback controller is designed. The robustly asymptotic stability in this system with the known L2 gain is thus guaranteed on the arbitrarily switched condition. The validity of the method proposed is verified by numerical examples. References | Related Articles | Metrics

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Application of improved PCA to fault diagnosis for vacuum consumable electric-arc furnace Jia, Ming-Xing (1); Wang, Fu-Li (1); Guo, Xiao-Ping (3); Niu, Da-Peng (1) 2007, 28 (9):  1221-1224.  DOI: - Abstract ( 300 )   HTML   PDF (462KB) ( 827 )   For some processes in which the mean values of process variables vary in different phases, a new fault diagnosis approach based on improved principal component analysis (PCA) was proposed. The state of process variables are transformed by a high-pass filter for system extension, then PCA is applied to the output of the extended system to develop a statistical model, by which the process monitoring and fault diagnosis are both available. This method can eliminate the negative effect of mean value change on the conventional PCA model and improve further the robustness and sensitivity of fault diagnosis. The method was applied to diagnosing the fault of cooling water leakage of the system of vacuum consumable electric-arc (VCEA) furnace, and the simulation results showed that the proposed method is effective. References | Related Articles | Metrics

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An improved simulation algorithm based on multi-thread for NC milling process Cui, Dong-Liang (1); Zhang, Yao-Peng (2) 2007, 28 (9):  1225-1228.  DOI: - Abstract ( 269 )   HTML   PDF (272KB) ( 666 )   An improved algorithm for Z-map and Z-buffer was proposed according to the common simulation frame of machining process to optimize the simulation system so as to verify NC programs and improving machining conditions. Introducing the idea about the useful sideline into the simulation process, the repeated operation of different comparisons are compacted, with the Z-buffer restructured from Z-map by way of height interpolation and the computational complexity of cutting process reduced through reference planes. Moreover, a multi-thread approach is proposed as an implementation frame to improve the practicality of the algorithm. Testing data show that the algorithm is of high efficiency in practice and the multi-thread frame can serve the function of making the simulation more reasonable and the response speed quicker. References | Related Articles | Metrics

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A short-term load forecasting approach based on support vector machine with adaptive particle swarm optimization algorithm Liu, Jia (1); Li, Dan (1); Gao, Li-Qun (1); Lu, Shun (1) 2007, 28 (9):  1229-1232.  DOI: - Abstract ( 239 )   HTML   PDF (275KB) ( 617 )   Aiming at the precocious convergence problem of particle swarm optimization algorithm, an adaptive particle swarm optimization algorithm (APSO) is presented, in which the inertia weight is nonlinearly adjusted by the information on population diversity and then the velocity mutation factor and position interchange factor are both introduced in to get rid of the constrict due to precocious convergence with fast hunting speed kept as previous. The algorithm has been applied to the optimization of parameters in SVM. A short-term load forecasting model based on SVM with adaptive particle swarm optimization algorithm (APSO-SVM) is thus presented. The simulation results showed that APSO-SVM can offer more accurate forecasting result than conventional SVM method. Therefore, the approach is efficient and practical to a short-term load forecasting of electric power system. References | Related Articles | Metrics

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Immune genetic algorithm for the single level capacitated lot-sizing problem Ma, Jia (1); Gao, Li-Qun (1); Li, Dan (1); Liu, Jia (1) 2007, 28 (9):  1233-1237.  DOI: - Abstract ( 265 )   HTML   PDF (234KB) ( 653 )   Analyzing the model of the single level capacitated lot-sizing problem (SLCLSP), a new approach based on IGA (immune genetic algorithm) is proposed to solve the problem. It not only retains the global research ability of SGA (simple genetic algorithm) but also adopts some strategies to keep up the diversity of biological immunity mechanism so as to improve greatly the diversity of population of SGA. Experimental results showed that the proposed IGA can rise above efficiently such difficulties of SGA as precocious convergence and poor local search ability and provide well the global converging ability'to enhance both the global convergency and convergence rate, thus solving effectively the SLCLSP problem. References | Related Articles | Metrics

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A dynamic double-population particle swarm optimization algorithm for flexible job-shop scheduling Li, Dan (1); Gao, Li-Qun (1); Ma, Jia (1); Li, Yang (1) 2007, 28 (9):  1238-1242.  DOI: - Abstract ( 286 )   HTML   PDF (236KB) ( 572 )   A dynamic double-population particle swarm optimization (DPSO) algorithm is presented to solve the problem that the standard PSO algorithm is easy to fall into a locally optimized point, where the population is divided into two sub-populations varying with their own evolutionary learning strategies and the information exchange between them. The algorithm thus improves its solvability for global optimization to avoid effectively the precocious convergence. Then, an ordering algorithm based on DPSO is integrated with the heuristic assignation (HA) algorithm to form a new algorithm DPSO-HA so as to solve the flexible job-shop scheduling problem (FJSP). The new algorithm is applied to a set of benchmark problems as instances, and the simulation results show the effectiveness and feasibility of DPSO-HA algorithm for the flexible job-shop scheduling. References | Related Articles | Metrics

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Analysis of rough set theory on attribute subdivision Kong, Zhi (1); Gao, Li-Qun (1); Wang, Li-Fu (1); Li, Yang (1) 2007, 28 (9):  1243-1246.  DOI: - Abstract ( 164 )   HTML   PDF (156KB) ( 777 )   The definitions of effectively equivalent class subdivision and effective set subdivision are given to the decision system by rough set theory. The influence of the necessary attributes after class subdivision on the upper and lower approximate values, quality and accuracy of approximate classification, number of decision-making rules and relative reduction are analyzed theoretically. Three cases concerning different subdivision regions are discussed with relevant results obtained. It is theoretically revealed that the finer the effective set subdivided, the closer the lower and upper approximate values to the original set and the higher the quality and accuracy of approximate classification and, at the same time, the more the number of the decision-making rules increased. In addition, the relative reduction and the necessity and unnecessity of attributes all remain unchanged. The results revealed provide an actual significance to the attribute reduction, formation of decision-making rules and their effectiveness. References | Related Articles | Metrics

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A global optimization algorithm based on filled-function for neural networks Li, Hong-Ru (1); Li, Hai-Long (1) 2007, 28 (9):  1247-1249.  DOI: - Abstract ( 274 )   HTML   PDF (178KB) ( 623 )   A novel global optimization training algorithm was constructed for the feed-forward neural networks to which the BP algorithm is easy to fall into the local minimum point for improper choice of initial weights. A new filled-function is therefore proposed with its nature of being filled-in proved. Then, the function is combined with BP algorithm to construct a global hybrid optimization algorithm. When it is used to train the neural networks in which the error function has fell into a local minimum point, it can apply the filled-function to helping the error function to uninterruptedly get rid of the point till a globally optimum point is found. So, its best advantage is independent of the chosen initial weights which makes the BP algorithm easy to fall into local minimum point. The simulation results and theoretic analysis show that this new algorithm is of efficiency and superiority. References | Related Articles | Metrics

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Design and realization of the project reconfigurable process system Peng, Wu-Liang (1); Zhou, Li (2); Qu, Rong-Xia (1) 2007, 28 (9):  1250-1253.  DOI: - Abstract ( 305 )   HTML   PDF (788KB) ( 540 )   The process reconfiguration of a project is of significance to restructuring the business processes of a company and enhancing the efficiency of its management. So, the behavior of the person in charge of a project and all managers and members in the project process is analyzed with a reconfigurable process management model developed by the IDEFO method. The model helps to reconfigure the management operation process of the project in accordance to its category and characteristics. Based on the given process model, different object-oriented submodels are available to develop for special applications. A project process management information system (PPMIS) is formed on the J2EE platform. The model has been verified available to improve the maturity of the enterprise project management through the PPMIS practice in a company. References | Related Articles | Metrics

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A security-provable analysis of group authenticated key agreement protocol and its improvement Zhu, Hong-Feng (1); Liu, Tian-Hua (1); Chang, Gui-Ran (1) 2007, 28 (9):  1254-1257.  DOI: - Abstract ( 362 )   HTML   PDF (151KB) ( 625 )   It is verified that there are possibly a valid attack on the negotiated open-ended cryptographic protocol N-Party EKE-U and a flaw which will make the protocol invalid. The attack refers to the peculiarity that the identity of every participant in the open-ended protocol is unlimited, then the protocol cannot resist the finite coordinated attack. The flaw refers to the uncertainty of message identity, which leads the protocol to be unable to execute normally. Analyzing the causes of such flaws in security, an improved protocol named N-Party EKE-UI is proposed to ensure not only the provable security in RO model but also no higher complexity found due to increasing communication rounds arising from the increasing number of participants. Furthermore, the protocol N-Party EKE-UI introduces the PAKE (password-authenticated key exchange) made to convenience users. So, it is of actual significance to solve the problem of 'open-ended' security protocol. References | Related Articles | Metrics

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A communication link evaluation model for wireless sensor networks Sun, Pei-Gang (1); Zhao, Hai (1); Luo, Ding-Ding (1); Zhang, Xi-Yuan (1) 2007, 28 (9):  1258-1261.  DOI: - Abstract ( 263 )   HTML   PDF (279KB) ( 757 )   It is often assumed that the bottom channel is an ideal one in routing protocol simulation and design of wireless sensor networks. As a result, the routing protocol thus designed causes a very low performance of network in practical applications. The problem is, therefore, considered to solve by developing an evaluation model for 2.4GHz communication link with the CC2420 transceiver chip taken as a target. The analytic model is extensible to a certain degree, by which a required link evaluation model is available to any transceiver chips in different environment or at different network nodes by way of substituting simply the relevant model parameters into the corresponding receiver BER formula. The deriving process of the evaluation model is based on generic conditions, so the model is acceptable theoretically by most of bottom channel link simulation for wireless sensor networks and can provide reference for the protocol analyzers and designers at higher level. References | Related Articles | Metrics

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On the distribution of Misiurewicz points in M-J chaos-fractal spectrum Xu, Zhe (1); Yu, Hai (2); Zhu, Zhi-Liang (2); Zhu, Wei-Yong (1) 2007, 28 (9):  1262-1265.  DOI: - Abstract ( 181 )   HTML   PDF (1494KB) ( 608 )   Using the method of computer mathematic experiments, the nature of Misiurewicz points as the preperiodic points in M-J chaos-fractal spectrum and their distribution are studied. The topological relationship between the distribution of Misiurewicz points and that of M-set periodic-buds is thus given, with a recursion formula between them derived. As a result, a useful discussion is made on revealing further the internal structure of M-set images and the properties of its periodic and perperiodic points. References | Related Articles | Metrics

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On the vague relations with extended compositional operations Zhao, Fa-Xin (1); Ma, Zong-Min (1); Deng, Li-Guo (1) 2007, 28 (9):  1266-1269.  DOI: - Abstract ( 227 )   HTML   PDF (163KB) ( 722 )   Vague relations as generalized fuzzy relations are more powerful to express fuzzy information than fuzzy relations. Based on the vague set theory, the vague relations and relevant compositional operations are systemically studied by introducing the definitions of vague sets/norms and their properties so as to give the definitions of general relations between vague sets including reverse, null and identical relations. Then, the properties of the relational operations between them and related theorems are studied with necessary proofs given. Furthermore, the t-norms and s-norms are introduced into the compositional operations of vague relations with relevant theorems and proofs given. Thus, the application of the composite operation to making up for the missing data in approximate vague relations via max-t and min-5 composite is discussed. References | Related Articles | Metrics

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Hough transform with parameters chosen by LMSE method Zhang, Xiang-De (1); Wang, Qi (1); Huang, Ya-Ping (1); Cao, Yu (1) 2007, 28 (9):  1270-1273.  DOI: - Abstract ( 236 )   HTML   PDF (823KB) ( 836 )   To detect a figure accurately in an image with great background noise, an improved Hough transform with parameters screened by least mean square error (LMSE) method is proposed as follows. First, Hough transform is introduced to obtain the total number of votes in parametric space, and the parameters of which the vote is greater than the threshold value for voting are all screened out preliminarily. Then, the mean square errors of image edges are separately calculated corresponding to these parameters, and a set of parameters with LMSE is chosen as the final result of such detection. The approach proposed is compared with the Hough transform with fetching the maximum votes by applying them separately to the localization of the outer iris limbus. Experimental results showed that the approach proposed can offer more reasonable findings with higher resistance to noise and wider range of applications. References | Related Articles | Metrics

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Fuzzy formal concept analysis and fuzzy concept lattices Hu, Ming-Han (1); Zhang, Li (1); Ren, Fei-Liang (1) 2007, 28 (9):  1274-1277.  DOI: - Abstract ( 382 )   HTML   PDF (2191KB) ( 1255 )   In many application domains, information is complex and uncertain. Conventional formal concept analysis is unable to express fully the vague and uncertain information. The theory of fuzzy formal concept analysis is therefore introduced, which combines the fuzzy theory proposed by Zadeh with the theory of formal concept analysis. Some conclusions are drawn with a set of objects and a set of attributes proved in fuzzy formal context. Then, the fuzzy concept lattice is formed in fuzzy formal context, which is proved to be a complete one. Some examples are given to illustrate how to form the fuzzy concept lattice. References | Related Articles | Metrics

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Analysis of resistance heating process for cold-rolled strip samples Hua, Fu-An (1); Li, Jian-Ping (1); Zhao, Zhi-Guo (2); Wang, Guo-Dong (1) 2007, 28 (9):  1278-1281.  DOI: - Abstract ( 306 )   HTML   PDF (1158KB) ( 796 )   To determine the parameters such as input power, heating current, samples' temperature distribution, and their variations the resistance heating process of cold-rolled strip samples was investigated on the electric and thermal theories in combination with FEM. For the samples with definite size, the maximum output power, voltage and current of the transformer used are determined as 150 kW, 24 V and 10 kA, respectively. It was found that in the heating process, the input power mainly plays the role to increase the sample temperature and compensate for the energy loss due to thermal radiation, while the energy loss due to convection and conduction is negligible. When heating at a constant rate, the heating current required in the low and high temperature sections is higher than that in the intermediate section. The sample temperature field presents a trapezoidal distribution, i.e., high at the middle but low at both ends under the conductive influence of a pair of water-cooled clampers which tightly clamp the samples. References | Related Articles | Metrics

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Hot strip width prediction during rough rolling with PSO-neural network based on fuzzy clustering Ding, Jing-Guo (1); Jiao, Jing-Min (1); Zan, Pei (2); Liu, Xiang-Hua (1) 2007, 28 (9):  1282-1284+1292.  DOI: - Abstract ( 247 )   HTML   PDF (261KB) ( 755 )   To improve the width control precision of hot strip during rough rolling for prediction, the PSO (particle swarm optimization) algorithm is used to train neural network with the actually measured data in PANSTEEL. Then, the fuzzy clustering analysis is used to preprocess the data with reasonable sampling for self-learning so as to solve the problem of superfluous samples and slow learning speed. The calculation results of measured data showed that this method can control the prediction precision of hot strip width during rough rolling within ±6 mm with optimized structure of neural network and learning speed greatly improved. So, it is regarded as highly potential in application. References | Related Articles | Metrics

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Preparation of a new Cu-based self-lubricating composite Chen, Sui-Yuan (1); Xing, Rui-Rui (1); Liu, Chang-Sheng (1); Zhang, Shuang-Ding (1) 2007, 28 (9):  1285-1288.  DOI: - Abstract ( 287 )   HTML   PDF (480KB) ( 1349 )   With the atomized Cu-Ni-Sn-Pb alloy powder as matrix, and the additives W and nano-Al2O3 as strengthening phase, a new composite system was constituted taking molybdenum disulfide (MoS2) plus graphite of 1.5, 2.0, 2.5, 3.0 and 4wt.% as solid lubricant phase. Then, a new copper-based self-lubricating composite was prepared through powder metallurgy. The preparation process, structure and mechanical properties of its samples were studied by means of digital microstructure microscopy, XRD and micro Vickers. The results showed that: The optimized sintering process should be done at 880-900°C, for 3 hr, and the hardness and strength both decrease with increasing graphite content. Among the samples containing different graphite mass fractions, the copper-based self-lubricating composite containing 2wt.% graphite is regarded as better, of which the density is 6.41 g/cm3 and hardness 38 HV, and it has been proved basically available to meet the requirement for low-speed self-lubricating machines. References | Related Articles | Metrics

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Preparation of TiCN-TiN compound cladding by LC-LGN technology Yang, Yu-Ling (1); Liu, Chang-Sheng (2); Zhang, Duo (1); Zheng, Yi-Ran (2) 2007, 28 (9):  1289-1292.  DOI: - Abstract ( 329 )   HTML   PDF (372KB) ( 1042 )   TiCN-TiN compound cladding was prepared on the surface of the titanium alloy Ti-6Al-4V using the LC-LGN (laser cladding-laser gas nitriding) technology, where the 500 W pulsed YAG laser was taken as the irradiation source with the TiCN powder whose particle size is 3μm as remelting material and highly pure N2 which is coaxial with laser beam as shielding gas/nitriding element. The influence of laser parameters on the preparation of TiCN-TiN compound cladding was investigated experimently with XRD and micro Vickers. The results showed that the pulse frequency and scanning velocity are the main influencing factors on the formation of TiCN-TiN cladding when the laser power density and pulse width remain unchanged. It was revealed that the appropriate process parameters are the pulse frequency 15 Hz, pulse width 3.0 ms and scanning velocity 2.0 mm/s. Heavy oxidation is found in cladding process if the velocity is lower than 2.0 mm/s and the cladding will peel off due to low binding strength between it and substrate if higher than 2.0 mm/s. After such cladding treatment, the samples' microhardness HV0.2 of TiCN-TiN compound increase to about 14 GPa from 3.3 GPa without cladding, i.e., about 4 times higher than that of substrate. References | Related Articles | Metrics

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Effects of different microstructures of CuPCr alloy steel on its marine immersion corrosion behavior Dong, Jie (1); Cui, Wen-Fang (1); Zhang, Si-Xun (1); Liu, Chun-Ming (1) 2007, 28 (9):  1293-1296.  DOI: - Abstract ( 281 )   HTML   PDF (574KB) ( 531 )   To investigate the marine corrosion behavior of the CuPCr alloy steel with different microstructures, the bainite and ferrite plus pearlite structures were prepared after hot rolling at different cooling rates to provide specimens for fully immersed marine corrosion tests in which the corrosion was accelerated. The corrosion rate was determined by weight loss measurement. SEM, XRD and electrochemical characterization were used to evaluate the corrosion behaviors. The testing results showed that the bainitic structure can form compact corrosion layer on its surface in a shorter time, of which the corrosion resistance is obviously higher than ferrite plus pearlite structure. The uniform distribution of carbon in bainite decreases the number of microcells in substrate, thus reducing the corrosion current density of the steel. References | Related Articles | Metrics

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Corrosion behavior of hot-dip 5%Al-Zn alloy coated sheet steel exposed to different seawater zones in Qingdao Li, Xin (1); Li, Yan (2); Wei, Xu-Jun (1) 2007, 28 (9):  1297-1301.  DOI: - Abstract ( 281 )   HTML   PDF (1443KB) ( 605 )   Commercial hot dip 5% Al-Zn alloy coated sheet steel was investigated for its corrosion behavior in three different seawater zones at Qingdao site with electrochemical measurement, weight loss test and SEM. The results indicated that in immersion zone 5% Al-Zn alloy coating resists well to the seawater corrosion because of its low current density and highly protective products from corrosion. In tidal zone the biofouling was found somewhat on coupons with oxidized surface resulting from quite good aeration, and the corrosion rate of the coating exposed in this zone is obviously lower than that in immersion zone. As to splash zone, 5% Al-Zn alloy coating shows the best corrosion resistance without biofouling found, which may be attributed to the advantageous aeration in combination with the corrosion resistant effect of the products from corrosion itself. A conclusion is therefore drawn that the corrosion resistance of 5% Al-Zn alloy coating increases by 197% and 183% in splash and tidal zones, respectively in comparison with that in immersion zone, and this coating tends to suffer from local corrosion in immersion and tidal zones. References | Related Articles | Metrics

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Numerical simulation of magnetic flux density distributions in soft-contacting EMCC round billet. Part I: Mathematical/physical models and the validation of numerical results Li, Ben-Wen (1); Sun, Yang (1); Deng, An-Yuan (1); He, Ji-Cheng (1) 2007, 28 (9):  1302-1304.  DOI: - Abstract ( 235 )   HTML   PDF (912KB) ( 635 )   A very close to realistic production soft-contact EMCC (electromagnetic continuous casting) round billet mold was introduced, and the corresponding three dimensional mathematical model for electromagnetic fields was developed. The mathematical model was numerically solved using finite element method under well-posed conditions. After the validation of numerical results by experiments, the three dimensional distributions of magnetic flux density in the soft-contacting EMCC mold were systematically investigated. The errors between numerical and experimental values are less than 5 percent. The relations between magnetic flux density and all structural and operational parameters are obtained quantitatively, which will provide a theoretical quidance to the design and operation of soft-contacting EMCC round billet mold. References | Related Articles | Metrics

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Experimental investigation on pressure preoxidation for refractory gold concentrate in Hunan with cyaniding leaching Yang, Hong-Ying (1); Tong, Lin-Lin (1); Yin, Shu-Yan (1) 2007, 28 (9):  1305-1308.  DOI: - Abstract ( 251 )   HTML   PDF (178KB) ( 1306 )   The preprocessing technique for a refractory gold concentrate in Hunan Province PRC was investigated experimentally, which contains 11.28% arsenic and its direct cyaniding leaching rate of gold is 21.91%. The occurrence form of arsenic in concentrate is mainly the arsenopyrite, and the gold-bearing minerals are arsenopyrite and pyrite, where the minutely dipped gold grains are wrapped up by arsenopyrite and pyrite. After pressure preoxidation, an experiment was done to extract gold from refractory gold concentrate by cyaniding leaching. The optimal conditions for pressure preoxidation are: Initial acidity is 1 mol/L, content of sodium lingosulfonates 5 g/t, ratio of HNO3 to H2SO4 is 7:1, pressure 0.6 MPa, stirring speed 300 rpm, processing time 100 min at 100°C and sampling pulp density 20%. The results showed that after the pressure preoxidation, the cyaniding leaching rate of gold comes to 90.87%, i.e., 68.96% is increased in comparison with the process without pressure preoxidation. References | Related Articles | Metrics

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Average service life of zinc products in China Zhang, Jiang-Hui (1); Lu, Zhong-Wu (1) 2007, 28 (9):  1309-1312.  DOI: - Abstract ( 477 )   HTML   PDF (179KB) ( 1624 )   The consumption structure of zinc products from 1990 to 2004 in China is analyzed, for which the weighted averaging method is given to calculate the average service life of zine products. The result indicates that the average service life of the zinc products in China increased year by year in recent years on the whole because of the greatly increasing output of galvanized products and copper products. The calculation reveals that the depreciation/recovery period of the zinc products in China is 20 years. Thus, a data foundation is offered to calculate the cyclic consumption of zinc and predict the developmental trend of zinc products. References | Related Articles | Metrics

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On the rub-impact fault of bearings due to oil film instability Ma, Hui (1); Chen, Xue-Lian (2); Wang, Kai (3); Wen, Bang-Chun (1) 2007, 28 (9):  1313-1316.  DOI: - Abstract ( 328 )   HTML   PDF (451KB) ( 865 )   To investigate systematically the coupling fault caused by the interaction between oil-film instability and rotor-bearing rub-impact, the coupling fault was simulated on a rotor test rig with the vibration signals acquired from rotor's speed up/down. The vibration signals in vertical direction are analyzed by 3D-waterfall spectrum, reassigned wavelet scalograms, amplitude spectrum and axial trajectory. The results show that the reassigned wavelet scalogram can extract well the time and frequency information on the rub-impact fault. When the coupling fault of rub-impact with oil film instability occurs, the oil film instability plays a major role in the rotor system, and the rub-impact caused by oil film instability will result in the two combination frequency components due to rotating and oil whirling. In addition, axial trajectory is found irregular and chaotic because there is no common factors found in the combined frequencies, which make them irreducible. References | Related Articles | Metrics

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Study on a process control approach integrating SPC with EPC Cui, Jing-Wei (1); Xie, Li-Yang (1); Liu, Xiao-Xia (1) 2007, 28 (9):  1317-1320.  DOI: - Abstract ( 245 )   HTML   PDF (976KB) ( 837 )   Subquality products often occur in a transient phase during which the level of technological process transfers from one to another if the production is multi-product with small scale. To solve the problem that the transient phase is occurring with the step change in input procedure, a process control approach is designed integration SPC (statistical process control) with EPC (engineering process control) by introducing the system simulation for the manufacturing process comprising the 1st-order dynamic process and the steady-state disturbance ARMA (1, 1). Conventionally SPC and EPC as the means to reduce process fluctuation are quite distinct from each other, while the approach designed integrating SPC and EPC applies ARMA control chart to monitoring the whole manufacturing process with PI controller used to readjust the process. The simulation results showed that the approach is not only able to reduce the fluctuation of process output so as to upgrade the system performance but also potentially advantageous to the cost involved in readjusting it when necessary. References | Related Articles | Metrics

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Lubricating behaviour of colza oil with nano-SiO2 as additive Yan, Yu-Tao (1); Huo, Yu-Qiu (2); Sun, Zhi-Li (1) 2007, 28 (9):  1321-1324.  DOI: - Abstract ( 539 )   HTML   PDF (583KB) ( 1417 )   Nano-SiO2 particles were prepared by sol-gel method with tetraethyl-orthosilicate as raw material in the presence of ammonia as catalyst. The morphology and phase structure of nano-SiO2 particles were characterized by TEM. The tribological properties of colza oil lubricant which took nano-SiO2 particles as additive in different mass fractions were investigated on a four-ball friction/wear tester. The worn surface of the steel balls was observed by SEM and the surface element composition was determined by means of energy dispersion spectrometry. The results show that the nano-SiO2 particles are amorphousely spherical-shaped with single particle size about 50 nm, and they can provide high surface energy/activity, and make for the locked-in absorbing films. With the nano-SiO2 particles as additive, the PB and PD values of the colza oil lubricant increase significantly. The lubricating effect will be the best if the additive is 2.5 wt%, and in such a case the worn scar diameter is minimum. References | Related Articles | Metrics

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Static balancing of spatial 3-TPS parallel machine tool Cong, Heng-Bin (1); Meng, Xiang-Zhi (1); Yang, Liu (1) 2007, 28 (9):  1325-1328.  DOI: - Abstract ( 265 )   HTML   PDF (538KB) ( 683 )   The static balancing of the spatial 3-TPS parallel machine tool is discussed theoretically and simulated for its optimization. Analyzes how the inertia force or the moment of inertia due to the deal weight of 3-TPS affects the machine tool and how the force output from the bar actuators changes in its whole working space. Then, the inertia force or moment of inertia due to the deal weight of the machine tool is balanced by way of hydraulic/spring balance. As a result, the force output from the three bar actuators decreased greatly to keep the machine tool in static balance. References | Related Articles | Metrics

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Chemical embedding immobilization technique of microorganism used in oil contaminated wastewater remediation Xu, Xin-Yang (1); Gu, Ni-Na (1) 2007, 28 (9):  1329-1332+1353.  DOI: - Abstract ( 319 )   HTML   PDF (208KB) ( 702 )   According to the characteristics of thick oil contaminated wastewater in an asphalt plant in Panjin, four strains of microorganism named TA-11, TA-17, HA-9 and HD-1, which can degrade oil and CODCr of oil contaminated wastewater, were picked out from the oil contaminated soil and activated sludge of Panjin pitch plant wastewater treatment system, and then it was immobilized by chemical embedding technique. Through the conditional tests of immobilizing parameters, an improved co-immobilization technique with PVA and sodium alginate was determined, where the immobilizing gel was made from 10.5% PVA, 0.5% Na · Alg, 3% activated carbon and trace auxin. Experimental results showed that the four strains of microorganism immobilized in such a way are able to remove 62%, 65%, 68.5% and 66.5% of CODCr in oil contaminated wastewater after 64 hours, which was much higher than the removal rate by free bacterium. References | Related Articles | Metrics

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Preparation and characteristics of RE-doped TiO2 photocatalytic antibacterial materials Jiang, Li (1); Liu, Kui-Ren (2); Jian, Xiao-Qin (2); Wang, En-De (1) 2007, 28 (9):  1333-1337.  DOI: - Abstract ( 285 )   HTML   PDF (1338KB) ( 1058 )   The RE-doped TiO2 such as i.e. Ce/TiO2, Pr/TiO2, Gd/TiO2, Dy/TiO2, Y/TiO2 and Eu/TiO2, photocatalytic antibacterial films were prepared by sol-gel method in combination with spinning coating process. The effects of sintering schedule, temperature, time and doping amount on their bactericidal potency are investigated to determine the optimum conditions for preparing the six types of RE-doped TiO2 films mentioned above. The results revealed that the structures of all RE/TiO2 films are made up singly of anatase, except for the Ce/TiO2 films which contain few rutile in addition to anatase. However, all of their surfaces are found defective obviously. Comparing with the pure TiO2 films whose average bactericidal rate to E. Coli is 34%, that of all the above six films are over 90% because the RE doping improves greatly the photocatalytic materials in response to visible light. The films have durably high bactericidal rate and stability even after used repeatedly and treated or washed at high temperature and under high pressure without peel-off found, thus providing high performance and good prospects in application. References | Related Articles | Metrics

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Calculation method of flexural capacity of rectangular steel tube beams filled with steel-reinforced high-strength concrete Zhao, Tong-Feng (1); Wang, Lian-Guang (1); Wu, Shao-Min (2) 2007, 28 (9):  1338-1341.  DOI: - Abstract ( 458 )   HTML   PDF (976KB) ( 751 )   To study further the ultimate flexural capacity of a steel tube member filled with steel-reinforced high-strength concrete, its failure is divided into several modes according to the different positions of neutral axis. Then, an improved superposition method is introduced in the calculation of the cross-sectional bending capacity of flexural members of the rectangular steel tube beams filled with steel-reinforced high-strength concrete and the formula for typical failure mode is given to calculate the bending capacity in tensile region under conditions that both compressional and tensile region have yielded. The new method overcomes the shortcoming of simple and conventional superposition methods in calculation, which provides higher precision and the formula proposed can offer reference for engineering practice. References | Related Articles | Metrics

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- - 2007, 28 (9):  1342-1345.  DOI: - Abstract ( 365 )   HTML   PDF (157KB) ( 793 )   - References | Related Articles | Metrics

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- - 2007, 28 (9):  1346-1349.  DOI: - Abstract ( 219 )   HTML   PDF (166KB) ( 1243 )   - References | Related Articles | Metrics

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- - 2007, 28 (9):  1350-1353.  DOI: - Abstract ( 192 )   HTML   PDF (737KB) ( 587 )   - References | Related Articles | Metrics

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Model analysis of digital divide and empirical study on its narrowing with ICT Han, Jing (1); Yang, Xi-Huai (1); Jia, Jian-Feng (1) 2007, 28 (9):  1354-1357.  DOI: - Abstract ( 187 )   HTML   PDF (933KB) ( 531 )   The appearance of digital divide due to regional informational discrepancy is studied using Keith Griffin's model which was developed for the generation and propagation of the Green Revolution for agricultural production to develop an ICT propagation model, involving the information isoguants plotted. The ICT model is used to analyze user's different choices of communication technologies in different stages of informational development, and an ICT gap can be determined by the intersection of the isoquants in different stages and the capital-labor ratio of different users. The ICT gap can describe the size of the digital divide. An empirical analysis is made for the information popularization level in Liaoning Province by popularization index measuring. The results show that ICT is an efficient way to narrow the digital divide and give suggestion on how to further develop ICT and narrow the digital divide. References | Related Articles | Metrics

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Existence of local solutions to nonlinear evolutional population equations with random migration perturbation Liu, Chao (1); Sun, Tao (1); Duan, Xiao-Dong (2) 2007, 28 (9):  1358-1360+1364.  DOI: - Abstract ( 224 )   HTML   PDF (313KB) ( 573 )   Generally the mathematical models for population system take no account of the influence of exterior conditions. However, the number of migrating people is increasing rapidly along with the socio-economic development, and the random migration becomes an important perturbative factor to population system. Assuming that the random exterior conditions perturb people's migration, the theories of m-accretive operator and nonlinear semigroup, as the terms included in the nonlinear functional analysis, are applied to deriving the nonlinear equations of evolutional population with random migration perturbation in either definite case or random case, where A represents the m-accretive operator and B the condensing map. Consequently, the theorems proving the existence of local solutions to those equations are obtained. References | Related Articles | Metrics

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Study on the magnetization plateau and thermodynamic properties in spin ladder Ma, Yan (1); Wang, Jun-Yang (1); Du, An (1) 2007, 28 (9):  1361-1364.  DOI: - Abstract ( 151 )   HTML   PDF (314KB) ( 597 )   To investigate the magnetization and the effect of anisotropy on thermal properties in external magnetic field, the transfer matrix method is used to calculate exactly the solution to the magnetization in Ising spin ladder with S = 1 and S = 3/2 mixed together. It's found that if the closest neighboring interaction is ferromagnetic and the next closest interaction between two spin chains is antiferromagnetic, the plateaus of the magnetization m = 1/4 and m = 3/4 appear in the system, which are consistent with the positions where the magnetization plateaus are possibly appearing in quantum model. Novel dual-peak is observed on the curves of specific heat and susceptibility. References | Related Articles | Metrics

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SEM-ECC observations of dislocation structures in fatigued copper single crystals oriented for conjugate double slip Li, Xiao-Wu (1); Zhou, Yang (1); Yang, Rui-Qing (2); Su, Hui-He (2) 2007, 28 (9):  1365-1368.  DOI: - Abstract ( 186 )   HTML   PDF (1270KB) ( 689 )   The dislocation structures in cyclically saturated copper single crystals oriented towards [2¯23] and [1¯12] conjugate double slip were observed and analyzed using electron-channelling contrast technique in scanning electron microscopy (SEM-ECC). It was found that the persistent slip bands (PSBs) might exhibit different dislocation features depending upon crystallographic orientation, such as ladder structures in the [1¯12] crystal and irregular or partially regular cell structures aligned along the primary slip plane in the [2¯23] crystal. Moreover, the dislocation microstructures in deformation bands (DBs) formed in the [2¯23] crystal were observed comprising irregular dislocation walls and cells. For the crystals located on the [001]-[1¯11] side of the standard stereographic triangle, the dislocation structures change regularly with the variation in crystallographic orientation. When the orientation varies from the [1¯12] orientation to [1¯11] or [001], the dislocation structures would evolve from PSB ladders as cells or labyrinths. References | Related Articles | Metrics