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15 August 2011, Volume 32 Issue 8 Previous Issue    Next Issue
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Stability analysis for singular networked control systems with time-varying delays Du, Zhao-Ping (1); Zhang, Qing-Ling (1); Liu, Li-Li (1) 2011, 32 (8):  1065-1067.  DOI: - Abstract ( 270 )   HTML   PDF (664KB) ( 1066 )   The problems of stability and controller design for a class of singular networked control systems (NCS) with time-varying delay are considered. The sensor node is assumed to be time-driven, the controller and actuator are event-driven, and the time-varying delay is less than one sampling period. First, the model of the singular NCS is constructed. Then, using Lyapunov function and linear matrix inequality method, the sufficient condition of asymptotic stability for the singular NCS is given, and the state feedback control law can be obtained at the same time by using Matlab LMI toolbox. References | Related Articles | Metrics

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Selection of operation schemes based on set pair analysis Chen, Xiang-Yong (1); Jing, Yuan-Wei (1); Gong, Mao-Shui (2) 2011, 32 (8):  1068-1071.  DOI: - Abstract ( 317 )   HTML   PDF (327KB) ( 613 )   The selection of operation schemes is a critical step in the course of warfare command decision-making analysis, which directly affects the exertion of operation effectiveness and the result of operations. Set pair analysis (SPA) theory is used to solve the selection problems of the operation schemes by dealing with the uncertainty of the alternatives. Further, a multi-periods and multi-attributes selection method is proposed. By constructing the identical discrepancy contrary (IDC) relation degree, the impact of the uncertainty of the warfare alternatives on the transformation of battlefield situation is analyzed effectively, and the ranking order of set pair potential of each alternative on all attributes is obtained. A numerical example demonstrates the applicability and effectiveness of the method proposed. References | Related Articles | Metrics

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Assembly of single-walled carbon nanotube field-effect transistor using dielectrophoresis Wu, Cheng-Dong (1); Xu, Ke (2); Tian, Xiao-Jun (2); Dong, Zai-Li (2) 2011, 32 (8):  1072-1075.  DOI: - Abstract ( 300 )   HTML   PDF (1611KB) ( 707 )   With respect to the assembly of carbon nanotube field-effect transistors, the dielectrophoresis technology was used to assemble single-walled carbon nanotubes (SWCNTs) between micro-electrodes. The dielectrophoretic force driving SWCNTs in a non-uniform electric field was analyzed theoretically. The driving electric field of dielectrophoresis was simulated by the COMSOL software. A number of experiments were carried out, with the required experimental parameters for efficient assembling of SWCNTs obtained. AFM scanning and electrical properties of SWCNTs showed that the method can achieve the effective assembly of carbon nanotube field-effect transistors, and that it is also an effective method of assembly and manufacture for other one-dimensional nanomaterials assembly of nanoelectronic devices. References | Related Articles | Metrics

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A depth-first K-NN query algorithm based on filters Xie, Ying-Hong (1); Wu, Cheng-Dong (1); Zhang, Yun-Zhou (1); Li, Meng-Xin (2) 2011, 32 (8):  1076-1079+1096.  DOI: - Abstract ( 325 )   HTML   PDF (443KB) ( 427 )   To reduce the energy consumption for data query and prolong the lifetime of wireless sensor networks, a depth-first K-NN query algorithm based on filters is proposed(FKDF). In the FKDF algorithm, the K-NN query range is determined by setting filters for each node. As depth first traversal is carried out, the query information is formed by using adjacent list information of the query nodes. Then, a sink node delivers query information and waits for the query nodes sending back query results, thereby decreasing the average hops per query process needed consequently. Simulation results show that FKDF algorithm reduces the average hops per query process needed, compared with the FILA algorithm setting filters and the GPSR routing algorithm, and it can not only adapt to the dynamic network topology structure, but also realize the minimal query cost when the value of K changes constantly. References | Related Articles | Metrics

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Adaptive dynamic-cluster based target tracking strategy in wireless sensor networks Liu, Jun (1); Liu, Hui (2); Ye, Ning (1); Cui, Zhe (1) 2011, 32 (8):  1080-1083.  DOI: - Abstract ( 274 )   HTML   PDF (1180KB) ( 597 )   In view of the characteristics of wireless sensor networks (WSNs) and their high timeliness in target tracking, a tracking strategy based on dynamic clusters is proposed. When the target appears, analytic hierarchy process (AHP) is used to select a cluster head, and the tracking weight of a node is defined and used to judge whether the node should join in the cluster for tracking, based on the node management mechanism. During the tracking, the cluster activates suitable sensors to participate in the tracking task, and the range of the activation area is adaptively adjusted according to real-time tracking quality. Besides, an adaptive target recover mechanism is proposed to avoid target losing. After the target leaves, the cluster is deconstructed to release sensor resources. The NS2 simulation results indicate that the dynamic cluster strategy for target tracking can get high tracking rate at low cost of communication overhead. References | Related Articles | Metrics

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Real-time scheduling for time-triggered CAN systematic matrix in fault-tolerant mode Ding, Shan (1); Xie, Zhi-Qiang (1); Zhang, Shi (1); Deng, Qing-Xu (1) 2011, 32 (8):  1084-1087.  DOI: - Abstract ( 388 )   HTML   PDF (1162KB) ( 552 )   TTCAN(time-triggered CAN) is a protocol based on CAN bus and it considers the advantages of time-triggered mechanism. Since messages are diverse, it is hard to schedule real-time tasks which constitute TTCAN systematic matrix. So, a greatest common divisor (GCD) method is proposed to solve the problem, where genetic algorithm (GA) is used to optimize the scheduling table to improve the network utilization and timeliness in event-triggered tasks. Finally, fault-tolerant performance is analyzed and a method of behind-priority principle for arbitration windows is proposed. Experimental results indicate that the algorithm can optimize the scheduling table, thereby ensuring real-time transfer. References | Related Articles | Metrics

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Resilient guaranteed cost control for discrete-time singular interval systems Yang, Dong-Mei (1); Zhang, Zong-Yan (1) 2011, 32 (8):  1088-1091.  DOI: - Abstract ( 321 )   HTML   PDF (159KB) ( 671 )   The problem of resilient guaranteed cost control for a class of discrete-time singular interval systems is studied. The elements in a system matrix and input matrix are uncertain but vary in prescribed intervals. Guaranteed cost control is considered under additive and multiplicative perturbations. And the controller can be designed by solving a set of LMIs. The numerical example shows the effectiveness of the proposed method. References | Related Articles | Metrics

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An adaptive random walk algorithm for image segmentation Yi, Yu-Feng (1); Gao, Li-Qun (1); Cheng, Wei (1); Yu, Hong-Yin (1) 2011, 32 (8):  1092-1096.  DOI: - Abstract ( 525 )   HTML   PDF (1372KB) ( 701 )   To solve the problems that the description of image information is simple and the outline of the objective is easily influenced by background disturbances, an adaptive random walk (RW) image segmentation algorithm is proposed. A texture-based similarity weight expression is given, with the texture features introduced into RW algorithm for the first time to highlight the image structural information. In order to accurately calculate the weight between two adjacent nodes, an adaptive weight expression is proposed, i. e., the proportion of intensity-based and texture-based weights in weight expression will be adaptively calculated according to the image edge density. High-quality segmentation results can be achieved by solving Dirichlet boundary condition. The experiments demonstrates that the proposed algorithm accurately describes image structural information and is more applicable and accurate in comparison with graph cut (GC) and typical RW algorithms. References | Related Articles | Metrics

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An association rule-based method for finding generalized herbs suitable for syndromes Gong, Jun (1); Dong, Jun-Long (1); Liang, Mao-Xin (3); Tang, Jia-Fu (1) 2011, 32 (8):  1097-1100.  DOI: - Abstract ( 290 )   HTML   PDF (329KB) ( 812 )   A new method based on Chinese medicine literature and association rule technique is proposed to find the Chinese medicine composition rules orientated towards syndromes. Firstly, the strong correlation paired herbs with each syndrome are mined by traversing the whole database called "Pujifang Database Management System". Then, commonly used paired herbs are identified based on the number of syndromes healed by the strong correlation herbs. Finally, the most suitable syndrome for commonly paired herbs is estimated by the degrees of confidence and support and validated by the theory of traditional Chinese medicine. The method overcomes the drawback that the minimum support degree is lower in many studies. The results illustrate that the new method is effective and suitable to be used generally. References | Related Articles | Metrics

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An improved algorithm of k-space data acquisition for parallel MRI Wu, Chun-Li (1); Hu, Wen-Juan (1); Kan, Ru-Wen (2); Yu, Jian (1) 2011, 32 (8):  1101-1104+1110.  DOI: - Abstract ( 312 )   HTML   PDF (1905KB) ( 1260 )   To further reduce the imaging time and improve the image quality, an improved GRAPPA algorithm of finite impulse response (FIR) is presented. Compared with the conventional GRAPPA algorithms with fixed weights, the proposed algorithm considers the phase change of the weighted coefficients, has a better description for the correlation of k-space data, and is more consistent with the physical process of data fitting for parallel imaging. To demonstrate the validity of the improved algorithm, the simulation experiments were performed with the original data of brain and cardiac images. The reconstructed images and the mean square error (MSE) were obtained with a higher acceleration factor, and were compared with the conventional and other GRAPPA algorithms. The results show that the reconstructed images are clearer and the MSE value are much smaller using the proposed algorithm. Therefore, the improved k-space data acquisition algorithm is effective and feasible. References | Related Articles | Metrics

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Effects of deformation and heat treatment on microstructure and mechanical properties of Q420 heavy steel plates Li, Jing (1); Zhao, De-Wen (1); Liu, Xiang-Hua (1) 2011, 32 (8):  1105-1110.  DOI: - Abstract ( 307 )   HTML   PDF (2047KB) ( 692 )   The physical simulation process of Q420 ultra-heavy steel plates 100 mm thick was carried out. The optimized production technologies of Q420 steel plates with different quality levels were obtained by analyzing the effects of deformation and heat treatment processes on the microstructure and properties of Q420 steel plates. The results showed that the steel plates rolled with TMCP(thermo-mechanical control process) process have better properties and finer ferrites than those rolled with UPR(ultra-heavy plate rolling) process. After heat treatment, the plasticity and toughness of the rolled plates are greatly enhanced, with the finer ferrites obtained, but the strength of the plates decreases. The steel plates normalized at the same temperature after different hot-rolling processes have little differences in the properties, showing the rolling processes have little impact on the microstructure and properties of the normalized plates. References | Related Articles | Metrics

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Experimental study on annealing process of cold rolled Q345 steel Zhang, Ming-Ya (1); Zhu, Fu-Xian (1); Ma, Shi-Cheng (1); Zhang, Zi-Cheng (1) 2011, 32 (8):  1111-1114+1123.  DOI: - Abstract ( 454 )   HTML   PDF (1734KB) ( 585 )   For developing new kind of DP steel, Q345 steel was cold-rolled and then the continuous annealing process was simulated. Microstructural and mechanical results showed that the microstructure is complicated and the matrix is composed of ferrite, pearlite and martensite. The samples exhibit the high tensile strength and the low yield ratio. The elongation percentage is very low, only about 14%. Because of high carbon content, the conventional heat treatment process couldn't be adopted and only low soaking temperature and the higher starting temperature of rapid cooling should be adopted. References | Related Articles | Metrics

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Fast finite element method for flat rolling problems Song, Shu-Ni (1); Liu, Jing-Yi (1) 2011, 32 (8):  1115-1118.  DOI: - Abstract ( 291 )   HTML   PDF (1606KB) ( 504 )   The DN-Brent algorithm, a combination of damped Newton algorithm, which is based on the step-down idea for searching the damping factor in the Newtonian iterative direction, and one-dimensional Brent algorithm, which is based on the parabola interpolation idea, is employed in the rigid plastic finite element method to calculate rolling forces. Compared with the traditional Newton-Raphson (N-R) method, the computational results demonstrate that the rolling force values obtained by the two algorithms are both close to the practical measured values. However, the proposed algorithm needs less iteration numbers and CPU time, which verifies the accuracy and validity of the DN-Brent algorithm in the application of the rigid-plastic finite element method to the calculation of rolling forces. References | Related Articles | Metrics

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Flow field and circulation flow rate in RH with side-bottom blowing Geng, Dian-Qiao (1); Lei, Hong (1); He, Ji-Cheng (1) 2011, 32 (8):  1119-1123.  DOI: - Abstract ( 293 )   HTML   PDF (1175KB) ( 716 )   The numerical simulation method was employed to investigate the fluid flow and the effect of bottom-blowing location on the circulation flow rate in RH with side-bottom blowing. The numerical results indicated that for RH with bottom blowing, when the included angle is constant between the two lines connecting the bottom-blowing location with ladle center and connecting two snorkels, the circulation flow rate increases firstly and then decreases with the increasing distance between the bottom-blowing location and ladle center. When the distance between the bottom-blowing location and ladle center is constant, the circulation flow rate decreases with the increasing included angle. When the bottom-blowing gas flow rate is equal to 200 L/min, the circulation flow rate in RH with side-bottom blowing is up more than 25 percent. When the side-blowing gas flow rate is equal to zero, the circulation flow rate is 60%~100% greater than that in traditional RH. References | Related Articles | Metrics

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Experimental study on tar-free gasification of coal Wang, Lian-Yong (1); Cai, Jiu-Ju (1) 2011, 32 (8):  1124-1128.  DOI: - Abstract ( 264 )   HTML   PDF (1443KB) ( 629 )   Based on the characteristic analysis of the updraft gasifier and downdraft one, a throated twin-oxidation tar-free gasifier of coal was exploited, where tar-free gasification of coal was experimentally investigated. The effects of operational parameters on gasification performance indices were studied. The results showed that the throated twin-oxidation gasifier can reduce the tar concentration of gas and raise the heating value of gas. The tar concentration and the heating value of gas can reach 10 mg/m3 and 6466.9 kJ/m3, respectively. It entirely satisfies the various burners and heat technics' needs and makes the tar-free gasification of coal come true. Essentially, the effects of operational parameters on coal gasification performance indices are realized by changing the gasification temperature. The increase of gasification temperature can enhance the reaction rate of tar pyrolysis, thereby increasing the concentrations of CO and H2 and decreasing the concentrations of CO2 and tar of gas, and as a result, the heating value of gas increases. References | Related Articles | Metrics

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Coupling calculation of absoption coefficient and mean beam length of non-gray gas Yi, Zhi (1); Hu, Lan-Hui (2); Li, Guo-Jun (1); Chen, Hai-Geng (1) 2011, 32 (8):  1129-1132.  DOI: - Abstract ( 344 )   HTML   PDF (961KB) ( 583 )   Three kinds of relationships between characteristic parameters of gas radiation and mean beam lengths were found by using exponential wide band model, mean beam length calculation and Beer law. The emissivity, absorption coefficient and corresponding mean beam length in a non-gray gas system were obtained by coupling calculation, thus avoiding the absorption coefficient indispensable to inversely calculate a mean beam length. The results showed that compared with Hottel's chart and formula for mean beam lengths, the method presented in this paper is accurate enough to solve the problem of radiative heat transfer in engineering. Taking a zone of ternary reheating furnace model as an example, the emissivity and mean beam length for the slab and wall surfaces are calculated, which provides necessary conditions of calculating radiative heat transfer. References | Related Articles | Metrics

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Visible light-induced photocatalytic reduction of Cr(VI) in presence of methyl orange and titania-bearing blast furnace slag photocatalysts Lei, Xue-Fei (1); Xue, Xiang-Xin (2) 2011, 32 (8):  1133-1136.  DOI: - Abstract ( 333 )   HTML   PDF (980KB) ( 522 )   The feasibility to enhance the visible light-induced photocatalytic reduction efficiency of Cr(VI) in the presence of methyl orange (MO) and sulfate-modified titania-bearing blast furnace slag (STBBFS) photocatalyst was investigated at the different pH and different initial concentrations. The results showed that in the presence of MO, the photocatalytic reduction efficiency of Cr(VI) is significantly enhanced and the kinetic constant of compound systems is nearly 1.35 times higher than that of single Cr(VI). There exists a strong synergistic effect in the compound system, and the synergistic effect factors of Cr(IV) and MO are 18.3 and 39.8, respectively. During the whole experiment, the reduction efficiency of Cr(VI) and the decoloration efficiency of MO in the compound system are much higher than that of other two single systems. The presence of Na2SO4, NaCl, or NaNO3 in the reaction mixture has little effect on Cr(VI) reduction, but has a significant influence on the decoloration efficiency of MO. References | Related Articles | Metrics

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Analysis of zones in COREX melter gasifier by temperature gradient Zhou, Xiao-Lei (1); Han, Li-Hao (1); Wang, Qi (2); Yu, Ai-Bing (3) 2011, 32 (8):  1137-1140.  DOI: - Abstract ( 252 )   HTML   PDF (1350KB) ( 594 )   A physical thermal model of COREX melter gasifier was established. The data of the air temperatures in this model were measured with temperature sensors under different experimental conditions. The temperature gradient could be obtained by processing the data of the air temperatures in this model. The results showed that the packed bed, cohesive zone, drip zone and raceway in the melter gasifier could be roughly distinguished by analyzing temperature gradient along the vertical direction. The zones in the COREX melter gasifier could be described objectively by the method so as to analyze the impact of the operating conditions on the zones in the future studies. References | Related Articles | Metrics

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Extraction of molybdenum from low-grade molybdenum concentrates Yu, Juan (1); Yang, Hong-Ying (1); Chen, Yan-Jie (1); Fan, You-Jing (2) 2011, 32 (8):  1141-1144.  DOI: - Abstract ( 284 )   HTML   PDF (1823KB) ( 668 )   Using roasting, ammonia leaching and alkaline leaching, the extraction of molybdenum from low-grade molybdenum concentrates was studied. The experimental results showed that the addition of the sodium carbonate increases the leaching rate of molybdenum by accelerating the decomposition of calcium molybdate. The optimum conditions for the molybdenum extraction are as follows: the roasting temperature is 600°C, the roasting time 2 h, the ammonia leaching temperature 80°C, the excess coefficient of aqueous ammonia 1.4, the dosage of the sodium carbonate 467?kg/t and the ratio of liquid to solid 4:1. The leaching residue was treated by hydrochloric acid leaching (HCl) method and alkaline leaching (Na2CO3+NaOH) method separately to further leach molybdenum. The recovery rate of molybdenum in the residue is only 34.92% by the former method and, meanwhile, the leaching process by this method is difficult to control, showing that the method is not practicable. In the latter method, the dosages of the sodium carbonate and sodium hydroxide are 533 and 433 kg/t, respectively. The scale-up experiment showed that the total recovery rate of molybdenum is up to 96.8%. References | Related Articles | Metrics

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Effect of complexing agent citric acid on extraction Pr/Nd in P204-RECl3-LA system Wu, Wen-Yuan (1); Yin, Shao-Hua (1); Bian, Xue (1); Zhang, Bo (1) 2011, 32 (8):  1145-1148.  DOI: - Abstract ( 299 )   HTML   PDF (1356KB) ( 661 )   The effect of the content of citric acid on distribution ratio, separation coefficient and extraction capacity of Pr/Nd in the P204-RECl3-LA system was investigated. The di-(2-ethyl hexyl) phosphoric acid (P204) was used as an extraction solvent and a certain proportion of citric acid was added into the rare earth chloride (PrCl3 or NdCl3) solution in the presence of lactic acid. The results showed that the distribution ratio, separation coefficient and extraction capacity of Pr/Nd in the P204-RECl3-LA system containing citric acid are significantly higher than that of a single lactic acid system. The separation factor increases from 1.44 to 1.68 and the extraction capacity increases from 25.23 g/L to 28.53 g/L, which provides a theoretical and technical basis for the study of green cleaning extraction method of rare earth in the non-saponification extraction system. References | Related Articles | Metrics

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Research on cast and reheated microstructures of 6061 alloy by electromagnetic semi-continuous casting Wang, Ping (1); Li, Xiao-Feng (1); Wei, Chun-Ying (1); Cui, Jian-Zhong (1) 2011, 32 (8):  1149-1152.  DOI: - Abstract ( 278 )   HTML   PDF (1261KB) ( 501 )   The semi-solid billet of 6061 alloy was prepared by electromagnetic semi-continuous casting technology and the reheating experiments were carried out. The influence of holding temperature and time on quenching microstructures after reheating was studied by observing the microstructures of ingot and reheated billets. The results showed that 6061 ingot with fine and uniform equiaxed grain structure can be obtained by electromagnetic semi-continuous casting. The microstructure evolution is accelerated with the increase of holding temperature during reheating. Too high holding temperature is not good to the property of formed parts because of the coarse grain of quenching microstructure. The quenching microstructure turns out to be more spherical because the α-Al spheroidizes continuously with the increase of holding time, but the grain size increases obviously. The fine and uniform grain structure can be obtained by reheating at 610~630°C for 10~15 min. References | Related Articles | Metrics

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Sulfuration of c(2×2)-S superstructure on NiW alloy substrates Wang, Xue (1); Li, Cheng-Shan (2); Yu, Ze-Ming (2); Fan, Zhan-Guo (1) 2011, 32 (8):  1153-1156.  DOI: - Abstract ( 236 )   HTML   PDF (715KB) ( 481 )   Because of the similarity of chemical properties between sulfur and oxygen, the formation of c(2×2)-S superstructure on the surface of NiW substrates is effective to control the texture of the epitaxial oxide buffer layers on the surface of metal Ni substrates. A new technological route was put forward to form the c(2×2)-S superstructure on the surface of substrates by the sublimation (at 120°C), adsorption and desorption of elementary sulfur. The X-ray photoelectron spectra (XPS) analysis indicated that notable amount of S element can be observed on the metal substrates treated by the new method. The ratio of Ni atoms to S atoms is in accord with the coverage of c(2×2) structure which is 0.5. The results of the buffer layer prepared on the surface with c(2×2)-S superstructure showed that the new sulfuration method improves the physical and chemical properties of the surface of NiW substrates and is propitious for the growth of epitaxial oxide layers. References | Related Articles | Metrics

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Synthesis and characterization of advanced nonylphenol series asphalt emulsifiers Liang, Bo (1); Xi, Man (1); Wang, Qi (1); Zhang, Bao-Yan (1) 2011, 32 (8):  1157-1160.  DOI: - Abstract ( 236 )   HTML   PDF (1470KB) ( 542 )   Nonylphenol (NP for short) and diethanolamine were used as raw materials to synthesize one cationic and four amphoteric asphalt emulsifiers. The structure of emulsifiers was investigated by FT-IR. The effective content of reaction products was determined by chemical titration. Emulsifiers synthesized were used for preparing emulsified asphalt. The performance was tested, including emulsifying effectiveness, storage stability, mixing stability, normal viscosities, asphalt content, residues on screening and the property of wrapping coarse aggregate. The results demonstrated that the four emulsifiers have good properties. One of them can be used as a moderate-setting asphalt emulsifier; the others can be used as slow-setting asphalt emulsifiers. References | Related Articles | Metrics

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Reliability-based sensitivity design of an aero-engine turbine disk Yang, Zhou (1); Du, Zun-Ling (2); Zhang, Yi-Min (1) 2011, 32 (8):  1161-1164.  DOI: - Abstract ( 356 )   HTML   PDF (1603KB) ( 588 )   An approach combining Monte Carlo-stochastic finite element method and neural network is proposed for the reliability-based sensitivity design of a turbine disk. It can solve the problem that the explicit expression of the ultimate state equation of the aero-engine turbine disk can't be directly obtained because of its complicated structure. Considering such parameters of the turbine disk as the dimension of the geometry, material characteristics and randomness of the environmental load, the relational expression between the random response and random parameters is simulated using the nonlinear mapping function of neural network. Following the trained neural network, the first order second moment method is chosen to design the reliability. The effect of the parameters' means and variances on the reliability is achieved through the reliability-based sensitivity design of the turbine disk. The proposed method is verified by the structural reliability analysis software NESSUS. It provides a theoretical reference for reliability-based sensitivity design of the turbine disk. References | Related Articles | Metrics

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Truncated order statistics model for the reliability of common cause failure systems Wu, Ying (1); Xie, Li-Yang (1); Li, Jin-Dong (2); Li, Bing (3) 2011, 32 (8):  1165-1168.  DOI: - Abstract ( 311 )   HTML   PDF (1443KB) ( 525 )   According to the common cause failure mechanism and the conception of order statistics, by means of the mapping relation between sample strength distribution in a system and order statistics, new system reliability models are proposed on the basis of load-strength interference theory and two-end truncated order statistics for serial, parallel and k-out-of-n (F) voting systems, respectively. The Monte Carlo simulation validates the correctness of the proposed models. Reliability calculated by the two-end truncated order statistics model is more accordant with the actual reliability of a mechanical system, compared with that obtained by traditional independent failure models and common cause failure models. References | Related Articles | Metrics

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Amplitude reliability analysis of driving point anti-resonance vibratory machines Jiao, Chun-Wang (1); Wang, Qian-Qian (1); Wang, Fu-Bin (1); Liu, Jie (1) 2011, 32 (8):  1169-1172.  DOI: - Abstract ( 307 )   HTML   PDF (371KB) ( 520 )   The principle of driving point anti-resonance vibratory machines is introduced, with the expressions of the upper/lower body's steady amplitude derived. The concepts of the reliability and reliable exciting-frequency range of driving point anti-resonance vibratory machines are proposed. The randomness of vibratory machine parameters caused by manufacturing, installation and other errors is analyzed. Furthermore, the random perturbation method is used to analyze the amplitude response of the vibratory machine to the exciting frequency and to quantize the amplitude stability condition, thereby obtaining the exciting-frequency range in which the vibratory machine can work reliably. This work provides an effective approach to verifying the rationality of parameters selection and choosing the effective exciting-frequency range. Finally, a numerical example is given. References | Related Articles | Metrics

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Contact pressure distribution & macro-topography generating mechanisms of silicon wafer polishing Guan, Xue-Feng (1); Lü, Yu-Shan (2); Feng, Lian-Dong (2) 2011, 32 (8):  1173-1177.  DOI: - Abstract ( 335 )   HTML   PDF (1551KB) ( 603 )   In order to obtain the contact pressure distribution and its effect on the flatness of the silicon wafer in the chemical mechanical polishing process, the mechanical and mathematical models were developed from the aspect of practical application. The contact pressure distribution was calculated and analyzed with ANSYS, and then confirmed by polishing experiments. The contact pressure distribution and how it was affected by the parameters of a polishing pad were obtained, and the relationship between the non-uniform distribution of the contact pressure and the flatness errors of the polished silicon wafer was determined. The results show that the contact pressure distribution is non-uniform, with the maximum pressure occurring on the edge of the silicon wafer, which induce the flatness errors and the edge subsiding. Selecting Young's modulus and Poisson's ratio of the polishing pads properly can improve the uniformity of the contact pressure distribution and the flatness of the functional region of the wafer. References | Related Articles | Metrics

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Experimental research on the behavior of bigger oil mist particles flowing through clearance Yang, Wei-Hong (1); Song, Jin-Chun (1); Wang, Feng-Lin (1); Chen, Jian-Wen (1) 2011, 32 (8):  1178-1181.  DOI: - Abstract ( 248 )   HTML   PDF (1637KB) ( 552 )   Influencing factors are analyzed on the diameter variation and distribution of bigger oil mist particles flowing through a annular clearance. The results show that: when the clearance length is 20 mm, the bigger oil mist particles condense after flowing through the clearance, and the average size of the condensed oil mist particles decreases gradually with the increasing of the oil mist inlet pressure, intake pressure, radial clearance and air flow; when the clearance length is 60 mm, most of the bigger oil mist particles condense in the clearance, and the condensation efficiency increases gradually with the increasing of air flow; when air flow is constant, the condensation efficiency decreases with the increasing of the radial clearance. References | Related Articles | Metrics

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Effect of ultrasonic on the preparation of nanometer calcium carbonate Yu, Fu-Jia (1); Wang, Ze-Hong (1); Han, Yue-Xin (1) 2011, 32 (8):  1182-1185.  DOI: - Abstract ( 310 )   HTML   PDF (814KB) ( 815 )   The principle and method of nanometer calcium carbonate preparation are introduced. Under the ultrasonic condition, the effects of initial carbonizing temperature, density of Ca(OH)2 and flow rate of CO2 on nanometer calcium carbonate synthesis are investigated. The results show that the ultrasonic can strengthen the nanometer calcium carbonate preparation, improve the efficiency of mass and heat transfer, greatly enhance the supersaturation of calcium ions in the solution and induce rapid and uniform nucleations of the calcium carbonate. Moreover, the initial carbonizing temperature can be enhanced about 5°C because of ultrasonic, which can shorten the preparation time and improve the synthetic efficiency. On the basis of experimental investigation, the nanometer calcium carbonate powders with diameter of 20~30 nm were synthesized steadily under optimal process conditions in a homemade ultrasonic reactor. The results indicate that high-quality nanometer calcium carbonates with smaller and homogeneous size can be obtained by ultrasonic method. References | Related Articles | Metrics

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Experimental study on diversion drawing by stress-relieve sublevel caving method Cao, Jian-Li (1); Ren, Feng-Yu (1); Zhang, Jin-Jun (2); Yang, Qing-Ping (2) 2011, 32 (8):  1186-1189.  DOI: - Abstract ( 333 )   HTML   PDF (1143KB) ( 618 )   Stress-relieve sublevel caving is an effective method developed recent years to solve the problems caused by mining unstable and inclined medium-thick orebody, but it has disadvantages of high ore loss and dilution. To solve the problem, the reason for the high loss and dilution is analyzed in the light of the flowing characteristics of ore-rock granular in inclined medium-thick orebody. The diversion drawing technique is then proposed. The influence of the position of a draft on the loss and dilution was investigated comprehensively through physical simulation experiments. The effects of diversion drawing was compared with the results of non-diversion drawing experiments. It is found that the diversion drawing technique can significantly improve the ore loss ratio and dilution ratio, especially for the efficient recovery of the footwall ore residue. The parameters' range of stress-relieve and diversion were obtained through experiments. References | Related Articles | Metrics

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Study on genesis of volcanic rocks from Zhangjiakou formation in Sijiazi basin of Chifeng Peng, Yan-Dong (1); Xing, De-He (2); Bian, Xiong-Fei (2); Song, Wei-Min (2) 2011, 32 (8):  1190-1194.  DOI: - Abstract ( 491 )   HTML   PDF (1259KB) ( 509 )   According to the data obtained from 1:50000 regional geological survey carried out during recent years, the authors confirm the existence of the Zhangjiakou formation of Late Jurassic in the Sijiazi basin, Inner Mongolia. The Zhangjiakou formation can be divided into three subcycles, i. e., rhyolites, trachyte and trachyandesites. High-precise analysis of the major and trace elements shows that the volcanic rocks are characterized by relatively high SiO2, Al2O3, K2O and Na2O, and comparatively low MgO and TiO2 components. Rittmann index σ (in the range of 1.19 to 4.87) has the average value of 2.47, indicating that the rocks belong to high potassium calcium alkaline rock series. The volcanic rocks are obviously enriched in incompatible elements (K, Rb, Sr, Zr, Ba, Pb and Li), and depleted in compatible elements (Ti, Co, Ni, Cr and V). The REE content in the volcanic rocks is high. The distribution pattern is the right-incline. There is a slight low Eu and Ce negative abnormality. The REE characteristics show that the volcanic rocks were generated in the intraplate orogenic belt. The results of the comprehensive study on genesis and tectonic environment indicate that the volcanic rocks were mainly formed by the crust materials in a continental intraplate setting due to partial melting. References | Related Articles | Metrics

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Deformation forecast using improved self-adaptive grey model based on wavelet denoising Sha, Cheng-Man (1); Han, He-Xin (2); Yang, Dong-Mei (2) 2011, 32 (8):  1195-1197.  DOI: - Abstract ( 288 )   HTML   PDF (658KB) ( 498 )   An improved self-adaptive grey model based on wavelet denoising is studied to forecast the deformation of foundation trenches. As many factors may cause measured data to deviate from the real data during monitoring the deforming foundation trenches, a wavelet denoising method is first used to deal with the measured data of deformation. Then, the self-adaptive grey model is used to forecast the deformation with the initial value amended. An example based on the measured data of a foundation trench is given to show that deformation forecast results by the method combining the wavelet denoising and grey model is more precise than those by a conventional single grey model. References | Related Articles | Metrics

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Mechanical properties of rubber concrete-filled square steel tubular stub columns subjected to axial loading Liu, Yan-Hua (1); Liang, Li (1); Ren, Qing-Xin (2) 2011, 32 (8):  1198-1201+1209.  DOI: - Abstract ( 289 )   HTML   PDF (1268KB) ( 564 )   Experiments were carried out on eight rubber concrete-filled square steel tubular stub columns subjected to axial loading to study the influence of the rubber replacing ratio and rubber particle size on the compression mechanical properties of the columns. A simplified formula is proposed for calculating the axial bearing capacity of the columns. The test results show that the compressive strength and stiffness of the columns decrease with the increase of both rubber replacing ratio and rubber particle size. The simulation results are consistent with the experimental data, demonstrating that the formula can reasonably evaluate the ultimate bearing capacity of rubber concrete-filled steel tubular stub columns. References | Related Articles | Metrics

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Fuzzy comprehensive evaluation on performance of special fund for financial support to agriculture Song, Zhi-Hua (1); Han, Liang-Liang (1); Li, Kai (1) 2011, 32 (8):  1202-1205.  DOI: - Abstract ( 341 )   HTML   PDF (891KB) ( 629 )   According to the characteristics of the Special Fund for Financial Support to Agriculture, a performance evaluation system is proposed for the fund, with some factors taken as evaluating indices, including social efficiency, ecological benefits, economic efficiency, project initiating, implementation, approval and management, funds collection, financial regulations and financial supervision level. A primary model is developed for the evaluation using fuzzy theory and analytic hierarchy process. The model objectively reflects the performance rating of the special fund. The performance of each special fund for agriculture can be ranked according to the monodromies, calculated by the model, of the fuzzy comprehensive evaluation results. Furthermore, the model can be used to calculate the membership contrast coefficients of the fuzzy comprehensive evaluation results so as to obtain the internal structure information of the membership of various ratings. References | Related Articles | Metrics

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Restrictions on benefit expropriation: An improved model based on debt structures Wang, Yan-Hui (1); Zhuang, Yan-Qing (1); Lü, Qing-Jun (1) 2011, 32 (8):  1206-1209.  DOI: - Abstract ( 226 )   HTML   PDF (158KB) ( 813 )   Different debt structures have different effects on the corporate governance and different restrictions on the benefit expropriation of controlling shareholders as well. Therefore, a modified LLSV model is proposed by introducing debt structure factors to the benefit expropriation analysis theory of controlling shareholders. Using the related data of 844 Chinese listed companies, the model was tested and verified. It is found that the long-term debt of the debt maturity structure, the non-priority debt of the debt priority structure and the public debt of the debt layout structure have obviously strong restrictions on the benefit expropriation of controlling shareholders. References | Related Articles | Metrics

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Theoretical study on the binding energy of hydrogenic impurities in a semiconductor quantum dot Wei, Guo-Zhu (1); Li, Yuan (1); Gong, Wei-Jiang (1); Fan, Shuang (1) 2011, 32 (8):  1210-1212+1216.  DOI: - Abstract ( 397 )   HTML   PDF (933KB) ( 603 )   The binding energy of hydrogenic impurities in a cylindrical quantum dot was calculated with the one-dimensional finite-difference method. The effects of the electric field, magnetic field and position of an impurity on the binding energy were studied. When the impurity is located at the center of the quantum dot, the binding energy decreases with increasing electric field and effective radius, and when the impurity is located at the plane normal to the z axis and through the center of the quantum dot, the binding energy changes symmetrically with increasing distance away from the center of the quantum dot. However, when the impurity is located on the z axis, the symmetry vanishes because of the effect of the electric field. References | Related Articles | Metrics

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A method for solving the eigen-states of one-dimensional quantum systems Gong, Wei-Jiang (1); Fan, Shuang (1); Si, Xiu-Li (1); Wei, Guo-Zhu (1) 2011, 32 (8):  1213-1216.  DOI: - Abstract ( 235 )   HTML   PDF (262KB) ( 545 )   In order to derive a convenient solution to a one-dimensional quantum system, a method is presented to solve the one-dimensional quantum chain and quantum ring. The eigen-energy spectra of the two structures are compared by a geometric approach so as to further clarify the characteristics of the eigen-energy spectra. In addition, the changes in the eigen-energies are discussed in the presence of the fluctuated onsite energy, and the conditions are given under which the surface state in the quantum chain structure appears. On the other hand, no surface state appears in the quantum ring despite the fluctuation of the onsite energy. References | Related Articles | Metrics