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15 May 2011, Volume 32 Issue 5 Previous Issue    Next Issue
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Robust H∞ control for a kind of singular networked control system with short time-delay Wang, Yan-Feng (1); Jing, Yuan-Wei (1); Zhang, Si-Ying (1); Huang, Feng-Zhi (1) 2011, 32 (5):  609-613.  DOI: - Abstract ( 249 )   HTML   PDF (1671KB) ( 592 )   H∞ control was determined for a kind of networked control system (NCS) based on a regular, impulse-free, and linear time-invariant singular control system. For the NCS with clock-driven sensors, actuators, and event-driven controllers, given an uncertain time-delay with no more than one sampling period and a limited external disturbance, the sufficient condition of the existence of dynamic output feedback H∞ control law was derived through Lyapunov theory and linear matrix inequality. A corresponding design method is also presented. Validity of the proposed approach is demonstrated by a simulation example. References | Related Articles | Metrics

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Using a gray predictive model for controlling dynamic tension during cold rolling Zhang, Yan (1); Shao, Fu-Qun (1); Wang, Jun-Sheng (2); Liu, Yun-Jiang (2) 2011, 32 (5):  614-617.  DOI: - Abstract ( 279 )   HTML   PDF (1186KB) ( 790 )   Maintaining controlled tension in a cold rolling mill is difficult when parameters in conventional PID controllers are non-variable. By analyzing dynamic tension control theory of roller gap and velocity, a variable parameter PID controllers were designed. Using the grey predictive PID control to enhance stability and precision of the tension control, the simulation and application experiments results indicated that system dynamic response performance and disturbance depression was significantly enhanced. The system has more favorable characteristics over conventional PID controllers. References | Related Articles | Metrics

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Calculating the sensitivity matrix used in magnetic induction tomography Lü, Yi (1); Wang, Xu (1); Yang, Dan (1); Chen, Yu-Yan (1) 2011, 32 (5):  618-621.  DOI: - Abstract ( 910 )   HTML   PDF (1564KB) ( 1181 )   Magnetic induction tomography in biological tissues is a reconstruction method for complex conductivity distribution by measuring inductive voltage due to disturbances in an alternating magnetic field. A sensitivity matrix involves mapping changes of the conductivity distribution onto the induced voltage in a receiver coil. A method basad on finite element and compensation theary is presented for rapidly calculating the sensitivity matrix, and is applied to a variety of simulation experiments. Results indicate that a sensitivity matrix with single perturbation and multiple perturbations can be solved quickly using this method and thus it provides an effective means of image reconstruction of inverse problems in MIT. References | Related Articles | Metrics

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Modelling rolling force and rolling torque in a hot strip mill Li, Wei-Gang (1); Tan, Shu-Bin (1); Li, Jia-Bo (3); Li, Long (1) 2011, 32 (5):  622-625.  DOI: - Abstract ( 479 )   HTML   PDF (1815KB) ( 1030 )   A new model for a type of rolling force and rolling torque for finishing stands of a hot strip mill was investigated. A new formula unifying rolling force and rolling torque coefficients was used to simultaneously model rolling force and rolling torque. Its physical meaning is readily understood, and it involves only two impacting factors, namely reduction rate and the ratio of flattening radius to exit thickness. A method is provided for obtaining unknown parameters in the new formula. The parameter values obtained are universal for different steel grades and different finishing stands. Simulation and experimental results show that the new model improves prediction accuracy of rolling force and rolling torque and can be used in online control in a hot mill strip rolling process. References | Related Articles | Metrics

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Parallel query for a data warehouse utilizing MapReduce Shi, Jin-Gang (1); Bao, Yu-Bin (1); Leng, Fang-Ling (1); Yu, Ge (1) 2011, 32 (5):  626-629.  DOI: - Abstract ( 302 )   HTML   PDF (1285KB) ( 641 )   MapReduce is a highly efficient distributed and parallel computing framework, allowing users to readily manage large clusters in parallel computing. But the MapReduce framework is not compatible with traditional relational databases. This paper proposes a distributed relational database ChunkDB based on the chunk structure, and extends and redesigns the MapReduce framework to ensure compatibility with the ChunkDB database. Thus, scalability, ease of operation, the high parallelism of MapReduce were integrated with the advantages, including indexing, query optimization of a relational database. The ChunkDB database based on MapReduce provided fast and efficient parallel query for data warehouse applications. References | Related Articles | Metrics

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A constrained group nearest group query method for spatial databases Chen, Mo (1); Jia, Zi-Xi (2); Yu, Ge (2); Gu, Yu (2) 2011, 32 (5):  630-633.  DOI: - Abstract ( 228 )   HTML   PDF (1629KB) ( 571 )   Considering some real applications with the constraints of spatial database queries, we define a new type of query called constrained group nearest group query, and investigate query processing technology according to the "constraint" property. A constraint clustering algorithm is designed to ensure that the query point number of the result satisfies the constraint. MBM and SHR are employed to obtain initial results. Then, a pruning strategy is introduced to improve the iterative updating procedure, which enable the obtaining of optimal results. Experiments were implemented to verify the effectiveness and practicality of the method. References | Related Articles | Metrics

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Top-k similarity joins on probabilistic data based on earth mover's distance Xu, Jia (1); Yu, Ge (1); Gu, Yu (1); Bai, Qiu-Shi (1) 2011, 32 (5):  634-637.  DOI: - Abstract ( 237 )   HTML   PDF (1346KB) ( 714 )   Use the EMD(earth mover's distance) to measure the similarity between two probabilistic records. EMD is robust to outliers and minute probability shifting, but has a cubic time complexity. An algorithm, EMD-k Join, is proposed that speeds up the EMD-based similarity search by constructing an index for probabilistic data using the primal-dual theory in linear programming and thus eliminates unnecessary EMD calculations. Meanwhile, it improves performance of the join process by adopting range query as the main operation and gradually shrinking the search range. Experimental results on real data sets show that EMD-k Join dramatically improves efficiency of EMD-based top-k joins on probabilistic data. References | Related Articles | Metrics

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A PKI-based cross heterogeneous domain authentication model Yao, Yao (1); Wang, Xing-Wei (1); Jiang, Ding-De (1); Zhou, Fu-Cai (1) 2011, 32 (5):  638-641.  DOI: - Abstract ( 257 )   HTML   PDF (1320KB) ( 839 )   A new cross heterogeneous domain authentication model based primarily on PKI is proposed. Detailed authentication processes are designed when users access resources across heterogeneous domains in different domains. Cross-domain authentication between PKI and Kerberos domains can be accomplished, and mutual authentication is supported. Analysis was conducted on the protocol model. Theoretical analysis shows that the proposed scheme has good compatibility, expansibility, reliability, parallelism, and security. Thus, this model is suitable for PKI-based large-scale network environments for achieving cross-domain authentication between PKI and Kerberos domains. References | Related Articles | Metrics

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An adaptive block pilot scheme for OFDM systems Wang, Jin-Kuan (1); Han, Peng (1); Xu, Peng (1); Han, Ying-Hua (1) 2011, 32 (5):  642-645.  DOI: - Abstract ( 299 )   HTML   PDF (1024KB) ( 755 )   The inset method, modulation technique and transmit channel of block pilot signal was researched in order to improving the low channel using efficiency which brought by fixation of inset pilot density in traditional OFDM. Therefore an adaptive block pilot scheme with low complexity was proposed in response to a traditional OFDM system with fixed pilot having a lack of channel utilization. It is designed to react to environmental conditions and reduces the overall pilot overhead when ideal performance is guaranteed. Furthermore, placement of pilot signals and signaling to facilitate this adaptive operation were also addressed. Simulation results showed that the proposed scheme remarkably improves system performance with low pilot overhead compared to conventional schemes. References | Related Articles | Metrics

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Investigating the scale-free feature and evolution mechanism of complex networks Ge, Xin (1); Zhao, Hai (1); Zhang, Jun (1); Han, Xu (1) 2011, 32 (5):  646-649.  DOI: - Abstract ( 250 )   HTML   PDF (1150KB) ( 744 )   A general network model with growth and preference features is proposed according to basic mechanisms for evolution in complex networks. The model was analyzed via continuum dynamic theory. Networks generated according to a GP model followed power law distribution based on maximum likelihood theory, explaining the cause of formation of the power law phenomenon. In addition, the exponential cut-off degree distribution in networks and the evolution of Internet topology are researched using a GP model, analyzing the long term evolution of the Internet and the behavioral feature of nodes. References | Related Articles | Metrics

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A task fine-tuning algorithm to reduce preemption overhead of RM algorithm Zhao, Hai (1); Ning, Xuan-Jie (1); Zhao, Zhen-Yu (2); Shi, Chen (3) 2011, 32 (5):  650-653+666.  DOI: - Abstract ( 262 )   HTML   PDF (1392KB) ( 672 )   In embedded real-time applications based on embedded real-time operating systems, the task context switch overhead incurred by preemptions cannot be ignored compared with the overall system. To solve the problem, a preemption reduction algorithm is presented to reduce the occurrence of preemption. While quantitatively analyzing suspension time of fixed priority scheduling preemption actions, the blocked task set obstructed by low priority tasks and the determinant condition was deduced to avoid preemption in the arbitrary preemption moment by postponing high-priority tasks in hard real-time systems. Simulation results showed that the optimization strategy presented effectively reduced the number of task preemptions and the preemption overhead, while ensuring task scheduling. The algorithm postpones the running of high-priority tasks to avoid occurrence of unnecessary preemptions and guarantees that each task in the schedulable task set meets its deadline. Thus, the algorithm improves practical schedulable utilization of the RM algorithm by reducing preemption overhead in practical applications. References | Related Articles | Metrics

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Studies on the memory allocation algorithm of an AVR single chip real-time system Wang, Jia-Liang (1); Zhao, Hai (1); Pan, Rong (1); Cai, Peng-Hua (1) 2011, 32 (5):  654-657.  DOI: - Abstract ( 312 )   HTML   PDF (1462KB) ( 610 )   Given the limited capacity of AVR single chip memory, memory allocation and utilization can directly affect entire system performance. Memory allocation testing of a self-designed embedded operating system iDCX 128 indicated that system memory-space utilization efficiency was low after numerous memory allocation events due to use of a first fit algorithm. The memory allocation algorithm was improved by altering the structure of tasks stored in the memory and the allocation mechanism was made into a best fit algorithm. Experimental results demonstrated that the improved algorithm caused a small number of wasted storage units with a corresponding increase in execution time. Nevertheless, overall memory utilization was greatly improved. References | Related Articles | Metrics

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Application of feature selection and SVM for ECoG classification Liu, Chong (1); Li, Chun-Sheng (2); Zhao, Hai-Bin (1); Wang, Hong (1) 2011, 32 (5):  658-661.  DOI: - Abstract ( 468 )   HTML   PDF (658KB) ( 732 )   The motor imagery ECoG(electrocorticongraph) was investigated, specifically for classifying different imagined movements of the left little finger and tongue through ECoG, with BP(band power) of the ECoG signal extracted as the feature of BCI2005 competitive dataset I. Then Fisher, L0, and SVM-RFE were each used to select the best features. After a 10-fold cross validation of the training dataset, the features selected by SVM-RFE were the best of the three feature selection methods because it provided the lowest classification error rate and the least feature dimensionality. In addition, selected features of the training dataset were used to train a linear SVM model while selected features of the testing dataset were used to predict the labels by the model. Final classification accuracy was 94%. References | Related Articles | Metrics

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Strain hardening behavior and microstructural evolution of 30Mn20Al3 non-magnetic steel Qin, Xiao-Mei (1); Chen, Li-Qing (1); Deng, Wei (1); Di, Hong-Shuang (1) 2011, 32 (5):  662-666.  DOI: - Abstract ( 352 )   HTML   PDF (1552KB) ( 920 )   Cold rolled sheets of 30Mn20Al3 high manganese non-magnetic TWIP steel were tensile deformed after solution treatment at 1000 and 800°C for 10minutes. Microstructure evolution was observed by OM and TEM. Results indicated that strain hardening rate followed different patterns along with changes in true strain under different deformation stage, and the strain hardening exponent increased with increasing true strain. Dislocation slip was the dominant deformation mechanism for small deformations. As deformation amount increased, deformation twins appeared and the main deformation mechanism was the interaction between dislocation and deformation twins or between deformation twins. Grain size increased with increasing solution treatment temperature. Microstructure observation demonstrated that the number of deformation twins increased with increasing grain size, resulting in a greater "TWIP" effect in coarse-grained specimens than in fine-grained specimen. This can be attributed to the dependence on grain size of the critical stress for twin formation. References | Related Articles | Metrics

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Optimizing processing parameters for twin-roll strip casting using particle swarm optimization Cao, Guang-Ming (1); Li, Cheng-Gang (1); Liu, Zhen-Yu (1); Gao, Bo-Hong (2) 2011, 32 (5):  667-670.  DOI: - Abstract ( 461 )   HTML   PDF (1421KB) ( 709 )   In order to improve the flat, gauge control precision and surface quality of casting strips, processing parameters were optimized based on a kiss point position calculation model (combining a Bayesian neural network and a theoretical model) and using a particle swarm optimization method under given chemical composition and process constraint conditions. Optimized and experimental results showed good agreement. References | Related Articles | Metrics

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Analyzing roller leveling strategies for high-strength steel plates Cui, Li (1); Hu, Xian-Lei (1); Guo, Qiang (2); Liu, Xiang-Hua (1) 2011, 32 (5):  671-674.  DOI: - Abstract ( 349 )   HTML   PDF (1788KB) ( 716 )   With the advent of heavy grade steel plating, the problem of leveling high-strength steel plates has become a bottleneck in the development of high-strength steel. Curvature integration by elastic-plastic differences was used for high-strength plate leveling due to the leveling problem that frequently emerges during development of heavy grade high-strength steel. In this investigation, parameters including plastic deformation ratio, residual curvature, and leveling force were studied, given that the rating leveling force and plastic deformation ratio were the main facts restricting high-strength leveling. Finally, strategies for low capability levelers were obtained, including increased leveling pass, alteration roll pinching, and static pressure leveling, for leveling high-strength steel plates in production. References | Related Articles | Metrics

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Investigating deformation behavior of asymmetrically rolled Cu/Al bimetal clad sheets Zu, Guo-Yin (1); Li, Xiao-Bing (1); Ding, Ming-Ming (1); Yu, Jiu-Ming (1) 2011, 32 (5):  675-678.  DOI: - Abstract ( 661 )   HTML   PDF (1415KB) ( 1068 )   The effect of roll bonding parameters on deformation distribution of Cu/Al bimetal clad sheets fabricated by asymmetrical roll bonding was investigated. The stress state of the deformation zone was developed and used to analyze metal flow during the roll bonding process. The deformation proportion of hard component metal in the whole clad sheet increased as asynchronous speed ratio increased. Shear friction directly impacted the stress state of body metals, and cross shear had the most influence on metal flow and bonding strength. The reduction of both layers was directly proportional to total reduction, and the difference between hard and soft metals gradually diminished. References | Related Articles | Metrics

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Effect of different electromagnetic fields on the structure of dual-ingot casted 7075 aluminum alloy Wang, Gao-Song (1); Zhao, Zhi-Hao (1); Cui, Jian-Zhong (1); Dong, Shuai (1) 2011, 32 (5):  679-682+695.  DOI: - Abstract ( 290 )   HTML   PDF (1392KB) ( 607 )   Equipment for dual-ingot LFEC casting of 7075 aluminum alloy was developed utilizing a low frequency electromagnetic casting(LFEC) method. The equipment was used to achieve continuous and stable casting of the 7075 aluminum alloy, thus providing an experimental basis for muti-ingot LFEC in industrial production. The effects of different magnetic fields on the structure of 7075 aluminum alloy were compared using dual-ingot LFEC. When the current direction of adjacent coils was opposite, ingot macrostructure was better than with current oriented in the same direction; and grains were gradually refined as current increased. The best magnetic effect was achieved when current intensity was greater than 160A. Alloy microstructure was not improved when current frequency was less than or equal to 10Hz, or greater than or equal to 30Hz. At a current frequency of 20Hz, grains were relatively small and homogenous, while macrosegregation was significantly inhibited. References | Related Articles | Metrics

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Numerical simulation of gas reforming during smelting reduction Gao, Pan (1); Li, Qiang (1); Zou, Zong-Shu (1) 2011, 32 (5):  683-686.  DOI: - Abstract ( 258 )   HTML   PDF (1784KB) ( 770 )   Given the incomplete utilization of enthalpy heat in a two-step smelting reduction process, gas reforming was studied by using numerical simulation. Under fixed gas temperature and flux, carbon consumption increased with increasing of carbon-based packed bed height and decreasing carbon particle size, while water vapor consumption decreased with carbon-based packed bed height and decreasing carbon particle size; extent of oxidation of gas in the COREX decreased from 0.10 to 0.065, while oxidation of gas in the HIsmelt decreased from 0.625 to 0.223, and the heat was fully utilized. References | Related Articles | Metrics

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Effect of pattern geometric parameters on surface absorptance of silicon crystal wafers Wang, Ai-Hua (1); Cai, Jiu-Ju (1) 2011, 32 (5):  687-690.  DOI: - Abstract ( 518 )   HTML   PDF (1912KB) ( 722 )   The finite-difference time-domain(FDTD) method is employed to numerically examine the effect of various SiO2 trench sizes on the absorptance of silicon crystal wafers. Effective medium theory (EMT) is also used to help further explain absorptance predictions. The results show that EMT can readily predict spectral absorptance for sub-wavelength gratings. The cavity resonance effect may increase absorptance as trench width increases. The absorptance curves had strong oscillations at short wavelength when the period was comparable to the wavelength and the ratio of SiO2 trench width to the period was not too small. References | Related Articles | Metrics

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Kiln calcination of magnesium oxide using selective catalytic reduction Chen, Wen-Zhong (1); Li, Hong-Xia (1) 2011, 32 (5):  691-695.  DOI: - Abstract ( 275 )   HTML   PDF (1040KB) ( 678 )   The characteristics and hazards of magnesite calcining of kiln flue gas are discussed, along with principles and processes of the SCR denitrification method. Flow field of the SCR reactor was simulated by Fluent software using a standard turbulence model and a porous medium model. This SCR reactor is designed for high temperature factory kiln calcination of magnesite, and its design was further optimized by numerical simulation. Simulation results showed that installing a fluid regulator in the SCR reactor slightly improved flow field, and size of the fluid regulator lattice had little effect on the flow field. Simulation also revealed the optimum structure and location of guide plates, thereby providing excellent denitrification results. References | Related Articles | Metrics

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Effect of synthesis method on properties of NiFe2O4 matrix inert anode Zhang, Zhi-Gang (1); Yao, Guang-Chun (1); Zhang, Xiao (1); Liu, Yi-Han (1) 2011, 32 (5):  696-699.  DOI: - Abstract ( 281 )   HTML   PDF (1367KB) ( 511 )   Orthogonal testing, including four factors and three levels of each factor, was conducted to optimize preparation conditions for NiFe2O4 matrix inert anode. The effects of these factors on porosity were determined by range analysis and the primary and secondary factors were then analyzed. Porosity of the inert anode was most greatly affected by sintering temperature, followed in succession by nanopowder content, molding pressure, and sintering time. Adding the proper amount of nanopowder while increasing sintering temperature, sintering time, and molding pressure all decreased sample porosity. Optimum conditions were as follows: nanopowder content of 20%, molding pressure of 200MPa, sintering temperature of 1400°C, and sintering time of 6h. References | Related Articles | Metrics

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Effect of electric potential on chemical composition of surface on chalcopyrite in collectorless solution Yu, Juan (1); Yang, Hong-Ying (1); Fan, You-Jing (2); Chen, Yan-Jie (1) 2011, 32 (5):  700-703+707.  DOI: - Abstract ( 325 )   HTML   PDF (1271KB) ( 655 )   Chemical composition of the surface layer formed at different potentials in collectorless flotation solution at pH 6.97 was studied by cyclic voltammetry and X-ray photoelectron spectroscopy. The sulfur element existed in the surface layer mainly in the metastable phase forms of CuFe(1-x)S2, CuS2, and the stable phase of Sn- at open-circuit potential(OCP). When the potential increased to 0.1V/SCE, Sn- disappeared while plentiful amounts of S0 and a small quantity of S2O32-/SO42- species were found in the film. At potentials higher than 0.35V/SCE, the content of S0 in the surface layer was lower than that in the surface layer at 0.1V, although the content of S2O32-/SO42- species increased dramatically. In addition, Cu element was present in the surface layer at lower potential in the form of CuFe1-xS2, and CuO present at higher potentials. Fe existed in the surface layer at lower potentials in the form of FeOOH and Fe2O3, and large amounts of Fe(OH)3 precipitated on the chalcopyrite surface at higher potentials. References | Related Articles | Metrics

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Impact of the novel cathode convex on the electrolyte/aluminum interface wave in a reduction cell He, Zhu (1); Li, Bao-Kuan (1); Wang, Fang (1); Feng, Nai-Xiang (1) 2011, 32 (5):  704-707.  DOI: - Abstract ( 349 )   HTML   PDF (1718KB) ( 664 )   Reducing electric energy consumption of an aluminum reduction cell requires shortening of the anode-cathode distance (ACD), which requires a lower magnitude of liquid aluminum wave. A mathematical model of electrolyte/aluminum two-phase flow in reduction cells, based on a computational fluid dynamics (CFD) method and the commercial software Fluent, was developed to study the impact of the cathode convex on the electrolyte/aluminum interface wave. The magnitude of the two-phase interface wave was reduced 17.2% for cathode convexes, while also enhancing washout of the melt on the ledge. References | Related Articles | Metrics

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Studies on re-extraction of organics loaded with a P204-H3cit-NdCl3 system Wu, Wen-Yuan (1); Luo, Yao (1); Yin, Shao-Hua (1); Bian, Xue (1) 2011, 32 (5):  708-711.  DOI: - Abstract ( 263 )   HTML   PDF (1135KB) ( 627 )   The unsaponified P204-H3cit-NdCl3 extraction system can effectively solve the pollution problem of the saponification waste water in traditional Nd extraction separation systems. But further application of this method is limited by high acidity of the re-extraction process in this system.The effect on re-extraction ratio of re-extraction acidity, temperature, times, and stage was investigated through single-level re-extraction and cross-flow re-extractions. With these results as a foundation, further studies were conducted for countercurrent re-extraction with low acidity of 0.6mol/L and six stages. Results indicated that countercurrent re-extraction rate reached 100% compared to single-stage and cross-flow re-extraction, and acid consumption was significantly reduced to 50%. Acidity remaining after re-extraction was 0.3 mol/L, and this meets the industrical requirements of the rare earth extraction. These methods of unsaponified P204-H3cit-NdCl3 extraction provided a certain basis for the application of rare earth elements. References | Related Articles | Metrics

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Preparing La0.4Sr0.6TiO3 buffer on different seed layers using metal-organic deposition Luo, Qing-Wei (1); Ran, A-Qian (1); Hong, Song-Chol (1); Fan, Zhan-Guo (1) 2011, 32 (5):  712-715.  DOI: - Abstract ( 226 )   HTML   PDF (1562KB) ( 603 )   La0.4Sr0.6TiO3, LaTiO3, and SrTiO3 seed layers were prepared on biaxially textured Ni-5% W alloy substrates by metal-organic deposition (MOD) methodology, and then a La0.4Sr0.6TiO3 buffer layer was deposited on each seed layers. SEM imaging showed that the grains of seed layers had similar size and were distributed uniformly. The effect of different seed layers on the quality of LSTO films was investigated by XRD and SEM. Well-oriented, smooth, and dense La0.4Sr0.6TiO3 films were prepared on LaTiO3 seed layers under an Ar-4% H2 atmosphere with an annealing temperature of 950°C. References | Related Articles | Metrics

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Dynamics characteristics testing and parameter identification for joints of linear rolling guideway Sun, Wei (1); Wang, Bo (1); Wen, Bang-Chun (1) 2011, 32 (5):  716-719.  DOI: - Abstract ( 314 )   HTML   PDF (1567KB) ( 1519 )   Based on identification theory, an experiment identification flow for guideway joint dynamics characteristics is proposed, including marking test points, testing frequency response functions (FRF), dealing with test data, and programming identification algorithms. Dynamics testing and parameter identification was conducted on a THK guideway joint that had been assembled in the bed. Using the Matlab open source identification algorithm, dynamics characteristics for a normal direction were obtained, including mass matrix, stiffness matrix, viscosity damping matrix, and structural damping matrix. Validity of identifying guideway joint characteristics was verified. References | Related Articles | Metrics

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Using FEM to analyze stress intensity factors of slanted thermal fatigue cracking Yan, Ming (1); Zhang, Yi-Min (1); He, Xue-Hong (1); Li, He (1) 2011, 32 (5):  720-723.  DOI: - Abstract ( 268 )   HTML   PDF (978KB) ( 727 )   Stress intensity factors of slanted thermal fatigue cracking and the periodic change patterns of cracking growth angle were calculated using the finite element method (FEM) and maximum tangential stress criterion. During the heating process, thermal compression stress was generated inside the model causing squeezing and staggering between the two crack faces. Due to the fact that deformation caused by heat-induced compression plasticity was not freely reversible, tensile stress generated during the latter part of the cooling process made the crack open. Slanted thermal fatigue cracking during the heating process and during the initial part of the cooling process was entirely mode II, and KII reached maximum as the heating process finished; a I-II mixed mode occurred during the latter part of the cooling process. Both KI and Ke maximized at the end of cooling period, and cracking growth was most prevalent this period. References | Related Articles | Metrics

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Theory and application of single-mass anti-resonance vibration isolation vibration machinery Liu, Jin-Tao (1); Li, Xiao-Hao (1); Gao, Hong-Bo (1); Liu, Jie (1) 2011, 32 (5):  724-727.  DOI: - Abstract ( 419 )   HTML   PDF (1509KB) ( 762 )   A new type of anti-resonance vibration isolation vibration machinery, namely a single-mass anti-resonance vibration isolation vibrator, has been proposed by applying the dynamic anti-resonance principle DAVI(dynamic anti-vibration isolator) into a vibration machine. Based on the Lagrange equation, a dynamic model of this vibration machinery was established, along with deduction of the transmissibility expression. The effect of a counterweight on amplitude of the vibration machine was analyzed, and research was conducted on the calculation method for selecting dynamic parameters of the vibration machine. The isolation effect was verified by computer simulation and modeling experiments, and is superior to one-stage vibration isolation while approaching that of two-stage vibration isolation. The amplitude devalue can be almost ignored by selecting dynamic parameters, and amplitude devalue can also be compensated by adding properly vibration. References | Related Articles | Metrics

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Analysis and control of vehicle emergency braking stability on split-mu road surfaces Zhang, Si-Qi (1); Zhang, Tian-Xia (1); Zhou, Shu-Wen (1) 2011, 32 (5):  728-731.  DOI: - Abstract ( 378 )   HTML   PDF (1470KB) ( 941 )   Braking efficiency is unsatisfactory on split-mu road surfaces for vehicles equipped with conventional anti-lock braking systems. Conventional four-channel ABS braking on this type of road surface causes the vehicle to deviate from the desired direction, and three-channel ABS increases stopping distance. An active front steering control was designed to improve lateral stability while braking on split-mu road surfaces with four-channel ABS, thereby producing maximum braking force. A full function vehicle model was designed and assembled, and dynamic analysis was performed using multi-body dynamics software and Simulink for split-mu road surfaces where one side of the road was a strip of ice and the other side dry asphalt. Simulation results show that active front steering improves vehicle lateral stability under braking on split-mu road surfaces. References | Related Articles | Metrics

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Mobile positioning in blind environments (I): Pattern recognition algorithms for coded sequence pattern signposts Wang, Zhi (1); Wu, Li-Xin (1); Kong, Xiang-Qin (1) 2011, 32 (5):  732-735.  DOI: - Abstract ( 303 )   HTML   PDF (1403KB) ( 863 )   In order to meet the needs of navigation in blind environments lacking satellite navigation signals, a pattern recognition algorithm is proposed for positioning moving targets in a blind environment based on coded sequence pattern signposts and a monocular vision system. A new coded sequence pattern signpost carrying more valuable information was designed and fixed along the blind environment, with the signpost identified by its cental 3D coordinate. A calibrated monocular vision system was mounted on the target object to capture images with coded sequence pattern signposts. To interpret the coded sequence patterns, the SIFT(scale invariance feature transform) algorithm was used for identifying signposts, the Otsu method for image segmentation and boundary tracking, and the fast Hough algorithm for positioning signpost centers, thereby enabling inquiry into the coordinates of each signpost center according to its code pattern data base. Experimental results validated the proposed method and showed that the algorithm was effective, which established a signpost foundation of technology development of precision positioning for moving targets in blind environments. References | Related Articles | Metrics

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Mobile positioning in blind environments (II): Positioning moving targets based on a monocular vision system Wu, Li-Xin (1); Wang, Zhi (1); Kong, Xiang-Qin (1) 2011, 32 (5):  736-739+744.  DOI: - Abstract ( 311 )   HTML   PDF (1575KB) ( 925 )   This paper proposes a mobile positioning algorithm for moving targets in a blind environment without satellite navigation signals and based on coded sequence pattern signposts and a monocular vision system. The coded sequence pattern signposts were fixed along the blind environment. The 3D coordinates of the center of each coded pattern identified a signpost. A pinhole imaging model was then established using a camera equipped with through-the-lens distortion analysis. A calibrated monocular vision system was mounted on the target object to capture images with coded patterns. Image processing methods were used to interpret the coded sequence pattern signposts, and to inquire about the coordinates of the center of each signpost according to its code pattern. The translation and rotation parameters of the monocular vision system were computed by using a POSIT algorithm so as to compute the pose of a moving target. Experiment results indicated that the proposed method delivers fast and accurate pose estimation for moving targets in a blind environment without GNSS signals. References | Related Articles | Metrics

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Deep reduction/magnetic separation of laterite for concentration of Ni and Fe Li, Yan-Jun (1); Li, Shu-Fei (1); Han, Yue-Xin (1) 2011, 32 (5):  740-744.  DOI: - Abstract ( 424 )   HTML   PDF (1292KB) ( 744 )   Nickeliferous laterite ore was first treated by a deep reduction process with coal as reductant and calcium oxide as flux under fractional smelting conditions, then followed by magnetic separation for recovery of nickel and iron. Optimal reduction conditions were 1300°C for 120min at coal blending ratio 2:1. The main performance indices of the process were 5.01% nickel grade, 22.46% iron grade, and metal recovery of nickel and iron at 96.05 and 79.69%, respectively. Various characteristics of the reduction materials were investigated. It's indicated that metallic nickel and iron were eutectic. An increase in reduction temperature accelerated aggregation of the nickel and iron metal phase and increasing reduction time contributed to growth of metallic particles, thus making magnetic separation much easier. References | Related Articles | Metrics

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Using coupled fluid-solid theory to forecast tunnel water inflow Guo, Mu-Dan (1); Wang, Shu-Hong (1); Rong, Xiao-Yang (1); Yang, Hao (1) 2011, 32 (5):  745-748.  DOI: - Abstract ( 383 )   HTML   PDF (1617KB) ( 711 )   Water inflow is a key parameter in the design and construction of tunnels having excess water. According to survey information from the Dahuofang water conveyance project, a three-dimensional numerical model was constructed to simulate actual conditions, and coupled fluid-solid theory was used for analysis. At the same time, FISH function in FLAC3D was utilized to calculate the maximum water inflow and normal water inflow between sections 15+720 and 15+797. Flow velocity and potential for water-related calamity was greater in the frontage of the fault construction. Forecasted water inflow was correlated well with actual survey values. Therefore, it was recommended that during the construction process detection of frontage groundwater could be strengthened along with the timely use of grout to plug excess water flow. References | Related Articles | Metrics

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A prediction model based on Langmuir theory for equilibrium adsorption amount Zhang, Zhi-Jun (1); Liu, Jiong-Tian (1); Feng, Li (2); Zou, Wen-Jie (2) 2011, 32 (5):  749-751+756.  DOI: - Abstract ( 513 )   HTML   PDF (948KB) ( 2831 )   A model was developed to predict equilibrium adsorption amount in an adsorption reaction. The adsorption isotherm of kaolinite and montmorillonite adsorbing Ca2+ followed the Langmuir adsorption equation. Based on the Langmuir isothermal adsorption equation, a model was developed that is able to predict the equilibrium adsorption of single component adsorption reactions. Results calculated by the prediction model coincided with experimental results, indicating good reliability of the prediction model. References | Related Articles | Metrics

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A multi-phase group evaluation method based on density operator and its application Yi, Ping-Tao (1); Guo, Ya-Jun (1); Li, Wei-Wei (1) 2011, 32 (5):  752-756.  DOI: - Abstract ( 243 )   HTML   PDF (1702KB) ( 531 )   Research was conducted on a multi-phase group evaluation information aggregation method based on density operator. The weight of each evaluator was determined by degree of judgment dispersion and individual judgment accessing to group judgment. In addition, the multi-phase weighting vector was given through the notion of timing degree. Based on this, evaluation information was aggregated through a multi-approach. This aggregation method considered the evaluation information distribution density, which was not only at the same time but also at different times. Finally, an example is given to demonstrate the aggregation approach, and final evaluation results are analyzed. References | Related Articles | Metrics

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CBR decision model of adaptive control based on result domain matching Jing, Ke (1); Tang, Liang (2); Zhao, Xi-Nan (1) 2011, 32 (5):  757-760.  DOI: - Abstract ( 260 )   HTML   PDF (1273KB) ( 589 )   Deficiencies exist in research on cognition and the application of case matching mode. By analyzing the case reasoning decision mechanism, a case-based reasoning (CBR) model was constructed based on result domain matching for decision-making. After identifying modes of case matching, the model reasons decisions by self-adaptive control arithmetic. The model was applied to emergency rescue in a coal mine gas explosion accident, and numerical example and simulation results indicate that the proposed model makes the target case approximate ideal results, with good controllability of reasoning progress. References | Related Articles | Metrics