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15 July 2012, Volume 33 Issue 7 Previous Issue    Next Issue
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Modeling for multi-stage gas compression system based on GRBF neural network Chu, Fei (1); Dong, Shi-Jian (1); Wang, Fu-Li (2); Wang, Xiao-Gang (1) 2012, 33 (7):  913-916.  DOI: - Abstract ( 671 )   HTML   PDF (647KB) ( 627 )   Based on the gas system of gas-steam combined cycle power plant from a steelworks, a mechanistic model was established for the multi-stage gas compression system, which essentially consisted of scrubbers, centrifugal compressors and coolers. Adaptive genetic algorithm was applied to estimating the important parameters of the mechanistic model, which cannot be confirmed using the mechanistic model. Since there are many factors having effect on the performance of the multi-stage gas compression system, the mechanistic model may yield inaccurate results. Thus GRBF neural network was employed to correct the error of the mechanistic model. The hybrid model was established by connecting the mechanistic model and GRBF neural network in parallel. Models were applied to the practical gas system, and the results demonstrated that compared with the mechanistic model, the hybrid model has higher accuracy. References | Related Articles | Metrics

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Hypothesis testing based NLOS identification and minimum residual localization algorithm Cheng, Long (1); Wu, Cheng-Dong (1); Zhang, Yun-Zhou (1); Jia, Zi-Xi (1) 2012, 33 (7):  917-921.  DOI: - Abstract ( 698 )   HTML   PDF (882KB) ( 1022 )   The localization accuracy could be severely degraded due to the non-line-of-sight (NLOS) propagation in the indoor environment. A NLOS signal detection algorithm based on hypothesis testing was proposed, and a new particle swarm optimization algorithm based minimum residual localization algorithm was presented for the wireless sensor networks. The received signal strength and time-of-arrival (TOA) were used to distinguish between LOS and NLOS propagation based on hypothesis testing. Simulation results showed that compared with deviation analysis and fewer parameters of propagation model, this method has lower computation complexity. Finally, particle swarm optimization algorithm based minimum residual localization algorithm was proposed after propagation detection algorithm. The proposed method outperforms the existing weighted least square method and Fang method with better estimation accuracy. References | Related Articles | Metrics

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Stability analysis for switched singular NCSs with uncertain time-delay Xing, Wei (1); Lin, Yan-Yu (1); Li, Ning (1) 2012, 33 (7):  922-925.  DOI: - Abstract ( 508 )   HTML   PDF (226KB) ( 518 )   The stability analysis for a class of the regular and impulsive-free switched singular NCSs (networked control systems) with uncertain time-delay was studied. Based on the following two assumptions, the switched singular NCSs were modeled as asynchronous dynamical systems. One assumption was that the sensor node is time-driven, and the controller and actuator are event-driven. The other was that the uncertain transmission delay was less than one sampling period. The stability conditions of the systems were given with the Lyapunov function and LMI method, and the desired state feedback controllers were obtained at the same time as well. When the state feedback control laws were applied to the systems, the closed-loop systems are stable. Theoretical study and a simulation example were presented, and the results indicated the effectiveness of the proposed method. References | Related Articles | Metrics

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Finite element analysis of composite structure continuous temperature-measuring sensor for liquid steel Zhao, Shu-Mao (1); Mei, Guo-Hui (1); Zhang, Jiu (1); Xie, Zhi (1) 2012, 33 (7):  926-929.  DOI: - Abstract ( 575 )   HTML   PDF (905KB) ( 645 )   A composite structure sensor which was composed of Al2O3-C refractories containing 20% and 30% graphite was proposed to overcome the problem of slow response speed of continuous temperature-measuring system for liquid steel. To study the effectiveness and feasibility of the proposed sensor, a finite element method was used to investigate the heat transfer and transient thermal stress during start process of teeming for this sensor. The results indicated that the maximum thermal stress occurs at the inside wall of the sensor's body and closes to the junction between body and measuring section. The maximum stress is about 4 MPa, which is smaller than the strength of sensor. The adoption of composite structure can improve response rate obviously. To reach 98% of actual temperature, the proposed composite structure sensor needs only half of the time that the original sensor needs. References | Related Articles | Metrics

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Similar class merging based FCM for image segmentation Yi, Yu-Feng (1); Gao, Li-Qun (1); Guo, Li (3) 2012, 33 (7):  930-933.  DOI: - Abstract ( 554 )   HTML   PDF (529KB) ( 726 )   A similar class merging based FCM algorithm for image segmentation was proposed to solve the problems that the segmentation results of the traditional FCM based image segmentation algorithm are discrete in the spatial distribution and the object cannot be segmented accurately by the traditional FCM based method. Firstly, a global spatial similarity measure and a global intensity similarity measure were proposed and introduced into a novel distance metric to calculate the difference between the pixels and the cluster centers. Secondly, color histogram was used as a descriptor, and Bhattacharyya distance was used to calculate the similarity between any two classes. Finally, a maximal similarity based class merging strategy was used to obtain the final image segmentation results. The experimental results indicated that the proposed algorithm can obtain more accurate image segmentation results compared with FCM and KFCM methods. References | Related Articles | Metrics

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Wavelet variance-based EEG signals feature extraction of imagined movements Yan, Shi-Yu (1); Wang, Hong (1); Liu, Chong (1); Zhao, Hai-Bin (1) 2012, 33 (7):  934-937.  DOI: - Abstract ( 638 )   HTML   PDF (516KB) ( 1039 )   A wavelet variance-based method to extract feature was adopted for a BCI task of two different imagined movements, that is, the imaginary left and right hand movements. Firstly, the computational methods of wavelet transform and wavelet variance were discussed in depth, then the features of EEG signals from the electrodes C3 and C4 using the variances of wavelet coefficient were extracted based on the ERD/ERS phenomenon. Finally, they were classified by using a most simple linear classifier, and classification accuracy and time interval were taken as evaluation criteria for BCI system. The results showed that the maximum classification accuracy was 85% and the best time interval for classification was 4~6.5 s. On precondition of guaranteeing the accuracy, the method for feature extraction and classification described is more efficient and simpler than BCI competition and others, which can be regarded as a good reference. References | Related Articles | Metrics

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Carrier frequency offset estimation algorithm based on compressive sensing theory Du, Rui-Yan (1); Wang, Jin-Kuan (1); Liu, Fu-Lai (1) 2012, 33 (7):  938-940+944.  DOI: - Abstract ( 477 )   HTML   PDF (1324KB) ( 717 )   The carrier frequency offset (CFO) estimation problem was investigated for interleaved orthogonal frequency-division multiple-access (OFDMA) uplink systems. A CFO estimation algorithm was proposed on the compressive sensing theory. First, a CFO estimation model was given by using the sparse property of the CFO distribution. According to compressive sensing theory, the CFO estimation problem was transformed into convex optimization problem and the optimum sparse vector was obtained via CVX. The CFOs of all users could be effectively estimated by exploiting the location of non-zero elements in the sparse vector. The presented method could avoid the eigenvalue decomposition in the subspace methods, and would be more practical. Simulation results were presented to verify the efficiency of the proposed approach. References | Related Articles | Metrics

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Energy efficient routing algorithm based on ACS for WSN Wu, Di (1); Wen, Tao (1); Guo, Quan (2); Sheng, Guo-Jun (1) 2012, 33 (7):  941-944.  DOI: - Abstract ( 542 )   HTML   PDF (430KB) ( 703 )   To improve energy efficiency in wireless sensor network(WSN), an energy efficient routing algorithm was proposed on the basis of the self-adaptability and dynamic optimization of ant colony system(ACS) and the self-organized property of WSN. Residual energy was considered to compute local heuristic factor to optimize the path probability selection and balance energy consumption among nodes. Quality of each path was introduced into the global pheromone update, which was evaluated by using the path length, the average pheromone of the path, and the average residual energy of nodes in the path. Multiple dynamic optimized paths were explored and maintained between source nodes and Sink to improve the robustness of transmission. Simulation results indicated that the proposed algorithm can decrease delay, improve energy efficiency and prolong the lifetime of WSN. References | Related Articles | Metrics

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Study on new type weathering-resistance steel strip developed by twin-roll strip casting Qiu, Yi-Qing (1); Liu, Zhen-Yu (1); Zhou, Guo-Ping (1); Wang, Guo-Dong (1) 2012, 33 (7):  945-948.  DOI: - Abstract ( 479 )   HTML   PDF (1782KB) ( 605 )   The low-carbon steel strip containing P and Cu acquired through twin-roll strip casting process, was systematically analyzed by FE-EPMA, SEM, OM as well as constant temperature and humidity testing device. The results indicated that a P-rich layer is formed near the surface of twin-roll cast strip, while the P concentration in the matrix is far lower than the nominal content. After cold-rolling and annealing treatment, the strip containing P and Cu exhibits the better plasticity, and the elongation still keeps above 30% even at P content up to 0.26wt%. Simultaneously, it is far superior in corrosion resistance to that by the conventional process. Especially a dense phosphate layer will be formed on the surface after a certain corrosion time when the P content over 0.15 wt%, which makes the corrosion resistance excellent. References | Related Articles | Metrics

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Effect of ultra-fast cooling on cooling distortion for H-beam steel Zhao, Xian-Ming (1); Guo, Fei (1); Wang, Li-Na (1); Wu, Di (1) 2012, 33 (7):  949-952.  DOI: - Abstract ( 597 )   HTML   PDF (674KB) ( 728 )   Uneven temperature distribution in cooling process are produced inevitably, causing the uneven distortion phenomenon in H-beam cross section. This research focused on how to improve H-beam cooling distortion. The cooling distortion was simulated in the ultra-fast cooling process by finite element analysis software ANSYS. The simulation results are in good agreement with the measured data. The cause of out of square is large residual stress due to the uneven cooling rate between upper and lower groove of the H-beam. Both simulation results and measured data showed that the out of square can be solved by improving the structure of ultra-fast cooling equipment layout and process control mode. References | Related Articles | Metrics

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Effects of alloying elements and heat treatment on mechanical properties of 1000 MPa grade TRIP steels Wang, Chao (1); Ding, Hua (1); Yao, Chun-Fa (2); Tang, Zheng-You (1) 2012, 33 (7):  953-957.  DOI: - Abstract ( 534 )   HTML   PDF (1824KB) ( 746 )   To achieve the objective of both high strength and plasticity in TRIP (transformation induced plasticity) steels, the influences of alloying elements and isothermal treatment temperatures on mechanical properties were investigated by tensile test, SEM, TEM and XRD techniques. The results indicated that with the isothermal treatment temperature increasing, the yield strength and the tensile strength decrease initially then increase. Nevertheless, the elongation and the combination of strength and elongation follow the countrary trend of the strength. The maximum tensile strength of over 1000 MPa and combination of strength and elongation of 22080 MPa·% are achieved when the bainite isothermal temperature is below 320°C or above 480°C. When the isothermal treatment temperature is within the bainite region of 400°C, the highest elongation and combination of strength and elongation are 31% and 27150 MPa·%, respectively. If Si is substituted partially by Al, the tensile strength decreases. As 0.5% copper is added, the tensile strength increases while the total elongation value decreases. The combination of strength and elongation under such a condition is 25085 MPa·%. Thus, under certain heat treatment process, high tensile strength and elongation of steels containing proper alloying elements can be obtained. References | Related Articles | Metrics

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Effect of trace boron on high temperature brittle fracture of iron caused by trace sulfur Liu, Fu-Ming (1); Liu, Chun-Ming (1) 2012, 33 (7):  958-961.  DOI: - Abstract ( 517 )   HTML   PDF (829KB) ( 574 )   The high temperature brittle fracture caused by sulfur is one of key problems to restrict the production and the use of steel. Aiming at this problem, the effect of trace boron on the ductility and fracture mode of iron containing trace sulfur (mass fraction 0.006%) at high temperatures was investigated by tensile tests at high temperatures and SEM observations of fractured surfaces. The role of trace boron was discussed based on analysis of the segregation at interfaces by scanning Auger electron spectroscopy. The experimental results showed that the addition of trace boron increases markedly the high temperature ductility of iron containing trace sulfur and restrains the brittle fracture caused by the interface segregation of sulfur. Such effect of trace boron results from that trace boron can segregate to interfaces of iron, remarkably decreasing the segregation of sulfur and therefore restraining the formation of cavities at grain boundaries caused by intergranular segregation of sulfur. References | Related Articles | Metrics

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Synthesis of Fe nanoparticles by pulsed laser gas phase evaporation-liquid phase collection Chen, Sui-Yuan (1); Chen, Shuang-Jian (1); Liang, Jing (1); Liu, Chang-Sheng (1) 2012, 33 (7):  962-964+974.  DOI: - Abstract ( 459 )   HTML   PDF (607KB) ( 649 )   Fe nanoparticles were synthesized by a new method of pulse laser gas phase evaporation-liquid phase collection. The morphology, structure, magnetic properties and synthesis mechanism were studied by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and vibration magnetometer. The results showed that using 45# steel as the target, 20% ethylene glycol+80% ethanol as the liquid collection system, and N2 as the carrier gas, Fe nanoparticles are successfully prepared under the conditions of the laser power density 42 J/mm2, pulse width 3 ms, frequency 10 Hz, and the N2 flow 0.5 L/min. The particles are spherical and show a trend of chain connectivity, the main size of the Fe particles is 20~30 nm; the coercivity of iron nanoparticles is 523 Oe, the saturation magnetization is 45 emu/g. The plasma with Fe composition was generated from 45# steel target by pulsed laser ablation, after homogeneous nucleation and growing of crystal nucleus in the gas phase, Fe crystal nucleus grew up to nano-size Fe particles when they were carried by N2 into the liquid phase. Ethylene glycol in the liquid has played a role in the dispersion of Fe nanoparticles in situ. References | Related Articles | Metrics

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Superplastic behavior and deformation mechanisms of Al-12.7Si-0.7Mg alloy Zhou, Ge (1); Ding, Hua (1); Li, Zhuo-Liang (1); Cao, Fu-Rong (1) 2012, 33 (7):  965-969.  DOI: - Abstract ( 601 )   HTML   PDF (1552KB) ( 890 )   Superplastic tensile deformation tests of Al-12.7Si-0.7Mg alloy were performed on Instron5500 electronic universal material testing machine. The variations of elongation (δ) and strain rate sensitivity exponent (m) at different strain rates and different temperatures were obtained. The results showed that the strain rate sensitivity exponent and elongation reach up to 0.44 and 379%, respectively, at a temperature of 793 K and the strain rate of 1.67×10-4 s-1. The deformation mechanism map inside grains and power dissipation rate map were obtained. The power dissipation rate map was used to predict the processing regime of superplastic deformation. Within the appropriate processing regime, based on the deformation mechanism maps, Burgers vector compensated grain size and modulus compensated stress of Al-12.7Si-0.7Mg alloy at different temperatures were calculated to elucidate the superplastic deformation mechanism. References | Related Articles | Metrics

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Automatic control system of direct tension-type pilot cold rolling mill Li, Jian-Ping (1); Yang, Hong (1); Niu, Wen-Yong (1); Wang, Guo-Dong (1) 2012, 33 (7):  970-974.  DOI: - Abstract ( 486 )   HTML   PDF (1740KB) ( 668 )   To meet iron and steel enterprises requires to strengthen research capacity in cold-rolled production technology, State Key Laboratory of Rolling and Automation(RAL) independently designed and developed a new direct tension-type pilot cold rolling mill, which includes a vertical hydraulic automatic gauge control(HAGC) generating tension through the hydraulic cylinders and chucks on both sides of the horizontal direction to realize automatic tension control(ATC). The equipment constitute, main functions and features of direct tension-type pilot cold rolling mill were introduced briefly. The control system structure and the realization of automatic control functions were illustrated. The control precisions were gotten through system testing. The testing results showed that the experimental process may simulate the cold rolling production process to develop steel grade and research technology. References | Related Articles | Metrics

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Limit load analysis of simply supported circular plate under linearly and uniformly distributed load with MY criterion Zhang, Shun-Hu (1); Zhao, De-Wen (1); Wang, Li (1); Huang, Xin (2) 2012, 33 (7):  975-978.  DOI: - Abstract ( 544 )   HTML   PDF (699KB) ( 566 )   With MY(mean yield) criterion, the limit loads of simply supported circular plate under linearly and uniformly distributed load were analyzed, and two analytical solutions to two forms of loads were obtained. The solutions showed that both the limit loads are the function of circular plate radius a, radius of the maximum tangential stress location r0 and ultimate bending moment. The limit load of the first form calculated by the solution is compared with those based on Tresca, Mises, as well as TSS yield criteria. It is shown that Tresca criterion predicts a lower bound to the collapse load, while TSS criterion predicts an upper bound one. The limit load based on the MY criterion lies between the TSS and Tresca solutions, and the MY solution is closed to Mises solution. Besides, the effect of circular plate radius a on r0 is also discussed. References | Related Articles | Metrics

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Physical simulation of cohesive zone in COREX melter gasifier Zhou, Xiao-Lei (1); Luo, Zhi-Guo (1); Han, Li-Hao (1); Yu, Ai-Bing (1) 2012, 33 (7):  979-982.  DOI: - Abstract ( 601 )   HTML   PDF (1177KB) ( 606 )   In order to simulate the cohesive zone of COREX melter gasifier, a thermal physical model was established. With thermocouples and an observation panel, the bed information inside the model was obtained. In the experiment, the influences of operating parameters, such as discharge rate, wax/maize volume ratio, blast temperature and blast volume on the cohesive zone were investigated. It was found that, with the increase of the selected parameters values, the possibility of raceway collapsing increases. When the disharge rate is increased, the location of the cohesive zone becomes lower and its thickness decreases. When the wax/maize volume ratio is increased, the location of the cohesive zone becomes higher and its thickness increases before collapsing, and its location becomes lower and the thickness increases after collapsing. When the blast temperature is increased, the cohesive zone position becomes higher and its thickness increases before collapsing, and the cohesive zone position becomes lower and its thickness decreases after collapsing. When the blast volume is increased, the cohesive zone position becomes higher and its thickness increases before and after collapsing. References | Related Articles | Metrics

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Two-strand T-type tundish configuration optimization in continuous casting Zhong, Liang-Cai (1); Zhang, Guo (1); Lu, Bi-Wei (1); Liu, Xi-Hai (1) 2012, 33 (7):  983-986.  DOI: - Abstract ( 671 )   HTML   PDF (672KB) ( 627 )   A two-strand T-type tundish model was set up in the laboratory with 1:2.5 scale from a tundish prototype. The physical simulation experiment was conducted with Froude number being equal to each other. The results indicated that in the former tundish configuration, the minimum residence time, the peak concentration time, the mean residence time, the plug flow region proportion and the dead volume fraction are 35.00 s, 103.75 s, 273.42 s, 17.88%, 29.53%, respectively. The flow characteristics in the tundish with a turbulence inhibitor, a weir and two dams as its flow control devices can greatly be improved. The minimum residence time, the peak concentration time and the average residence time increase to 151.75 s, 281.25 s and 354.16 s, respectively in the thundish with the optimization configuration and the plug flow and dead volume fractions are 55.80% and 8.73%, respectively. References | Related Articles | Metrics

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Numerical simulation of blast furnace raceway with coke oven gas injection Guo, Tong-Lai (1); Liu, Zheng-Gen (1); Chu, Man-Sheng (1) 2012, 33 (7):  987-991.  DOI: - Abstract ( 666 )   HTML   PDF (899KB) ( 952 )   A raceway mathematical model of blast furnace with coke oven gas (COG) injection was established based on the theory of mass and heat balances. The effects of COG injection volume on the coke mass flow rate, theoretical flame temperature, bosh gas volume, bosh gas compositions and raceway shape were investigated systemically. The results showed that the theoretical flame temperature tends to decreasing and bosh gas volume tends to increasing, when COG injection volume increasing with the benchmark operation of blast furnace unchanged. The theoretical flame temperature and bosh gas volume can be constant by decreasing blast volume and increasing oxygen enrichment when blast furnace operating with coke oven gas injection. After thermal compensation, with increasing COG injection volume, the coke mass flow rate and reducing gas volume in bosh gas tend to increasing, and the raceway cubic capacity tends to narrowing. With 1 m3/s increasing of COG injection, the coke mass flow rate increases by 1.74%, the reducing gas volume in bosh gas increases by 2.04% and the raceway cubic capacity decreases by 1.98%. References | Related Articles | Metrics

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Removal of methyl orange from aqueous solution by nitric acid-modified titanium ore Lei, Xue-Fei (1); Xue, Xiang-Xin (2); Yang, He (2) 2012, 33 (7):  992-994+999.  DOI: - Abstract ( 491 )   HTML   PDF (509KB) ( 540 )   Nitric acid-modified titanium ore (NATO) sorbents were prepared by high energy ball milling process. The adsorption properties of NATO sorbents were evaluated by the decoloration efficiency of methyl orange (MO) under dark-state absorption. In the adsorption stage, L9(34) orthogonal experiments of different factors, for example, doping ratio, calcination temperature, soaking time and heating rate were performed. Based on the orthogonal experiments, the optimal operating parameters, 2.0wt% nitric acid, 300°C calcination temperature, 3 h soaking time, and 10°C/min heating rate, are obtained. In this optimal condition, the decoloration efficiency of MO reaches 96.8%, which is significantly better than the undoped samples. Thus, it is feasible to treat dye wastewater by these NATO sorbents. References | Related Articles | Metrics

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Extraction of Nickel(II) from laterite ore by pressure acid leaching-emulsion liquid membrane Jiang, Cheng-Zhi (1); Zhai, Xiu-Jing (1); Zhang, Ting-An (1); Hou, Ping (1) 2012, 33 (7):  995-999.  DOI: - Abstract ( 525 )   HTML   PDF (780KB) ( 566 )   An emulsion liquid membrane (ELM) process of Span80-TBP-NH3·H2O was presented for extraction of Nickel(II) from acidic leaching solution of laterite ore. The influence of temperature on the transport of Ni(II) through emulsion liquid membrane was studied, which showed that the emulsion liquid membrane(ELM) process of Span80-TBP-NH3·H2O was a chemical reaction controlling procedure. Demulsification experiments were carried out with ultrasonic-heating combined demulsification and heating-centrifugation combined emulsion breaking. The emulsion breaking rate may reach 98%. The membrane reactions in emulsion liquid membrane were investigated by FT-IR spectra method. The IR spectra comparison between the emulsions before and after nickel extraction confirmed the reactions in the membrane. The IR spectra comparison between the original oil and the oil after demulsification shows that the oil after demulsification can be reused. With such demulsified oil reused, the extraction rate of Nickel(II) from laterite ore can still reach 80% in the present pressure acid leaching-emulsion liquid membrane process. References | Related Articles | Metrics

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Influence of Na2O on properties of CaO-Al2O3 slag Shi, Guan-Yong (1); Zhang, Ting-An (1); Niu, Li-Ping (1); Dou, Zhi-He (1) 2012, 33 (7):  1000-1003.  DOI: - Abstract ( 569 )   HTML   PDF (863KB) ( 982 )   The effect of adding Na2O into the CaO-Al2O3 slag on the viscosities and melting points of the slags when w(CaO):w(Al2O3)=1.1 was investigated, and the influence of several different additives on the viscosities of the slags was compared. The results showed that with the increase of the Na2O content, the viscosities of the CaO-Al2O3 slags decrease at first and then increase, and reach the minimum value when mass fraction of Na2O is 4%. The melting points of the slags increase with increasing additive content of Na2O. The addition of Na2O, Li2O and MgO decreases the viscosities of the CaO-Al2O3 slags. The ability to reduce the viscosities of the slags in descending order is Li2O>Na2O>MgO. Considering the influence of Na2O on viscosities and melting points of CaO-Al2O3 slags, the dosage of Na2O in CaO-Al2O3 slags should not exceed 4%. References | Related Articles | Metrics

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Effect of copper(I) on existence form of gold, silver and other metal ions in cyanide solution Jong, Dae-Rok (1); Zhang, Ting-An (1); Kim, Chang-Sok (1); Zhao, Hong-Liang (1) 2012, 33 (7):  1004-1008.  DOI: - Abstract ( 705 )   HTML   PDF (900KB) ( 733 )   A formula was proposed to describe the existence form of metal and CN- ions in cyanide solution with various copper additions, metal ion concentrations and pH values. Based on the calculation results, the precipitation mechanisms of gold and silver were investigated when copper is added into cyanide solution containing gold and silver, and the causation was also discussed for that the cyanide consumption increased and the leaching rates of gold and silver decreased in condition of high copper content in the ore. When added into cyanide solution, the copper first reacted with free ions of cyanide and then "robbed" almost all of the CN- from cyanide complexes of zinc, cadmium and nickel. CN- was precipitated simultaneously as CuCN. The gold and silver complexes were "robbed" of CN- and precipitated as AuCN and AgCN, respectively. References | Related Articles | Metrics

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Study on fluctuation of interface in aluminum cell caused by gas exudation from anode carbon blocks Qi, Feng-Sheng (1); Yang, Liu (1); Li, Bao-Kuan (1); Feng, Nai-Xiang (1) 2012, 33 (7):  1009-1012.  DOI: - Abstract ( 542 )   HTML   PDF (977KB) ( 647 )   Interfacial fluctuation between electrolyte and aluminum plays an important role in stability and current efficiency of electrolytic aluminum process. A mathematical model of electrolyte/aluminum/gas multiphase flow in aluminum cells based on a computational fluid dynamics (CFD) method was built to study the interfacial fluctuation between electrolyte and aluminum caused by gas exudation. Furthermore, the effects of three different aluminum electrolysis cells were analyzed, including traditional, cuboid cathode and small cube cathode cell. The results showed that it takes 45 s for the fluctuation to reach a steady situation. After that, the changing of amplitude is very small. The interfacial fluctuations in three different aluminum electrolysis cells have same trend, and the wave amplitude in cuboid cathode aluminum cell is smaller than that in the others. References | Related Articles | Metrics

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Effect of temperature and atmosphere on stabilities of cubic Mn-stabilized zirconia Gao, Ling (1); Zhou, Lian (2); Lu, Ya-Feng (2); Li, Cheng-Shan (2) 2012, 33 (7):  1013-1016.  DOI: - Abstract ( 511 )   HTML   PDF (678KB) ( 983 )   The stability of cubic Mn-stabilized zirconia prepared by traditional solid-state reaction was investigated at different annealing temperatures and atmospheres. The results showed that when the concentration of Mn element is 20at.%, the zirconia is a cubic structure. For the single phase Mn-stabilized zirconia, the cubic phase is unstable and changes into a monoclinic structure at high oxygen partial pressure at the temperature higher than 1000°C, but relative stable at the lower partial pressure. When annealed at the temperature lower than 800°C, the cubic structure does not change, and it is not affected by the partial pressure. The differences are that when the cubic samples annealed at 800°C for longer time in O2, the lattice parameters of cubic zirconia become smaller and the valence state of Mn changes into higher valence. References | Related Articles | Metrics

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Research on dynamic characteristics of rotating blades under aerodynamic forces Tan, Zhen (1); Li, Chao-Feng (1); Zhang, Peng (1); Wen, Bang-Chun (1) 2012, 33 (7):  1017-1020+1029.  DOI: - Abstract ( 631 )   HTML   PDF (1302KB) ( 954 )   Air-structure coupling vibration is one of the influence factors of blades vibration. In order to study the dynamic characteristics of rotating blades under aerodynamic forces, the CFX and ANSYS were used to calculate the responses of flow field and structure, respectively. The coupling calculation method of blades under air excitation was discussed, and the transient dynamic response of the solid flexible structure was calculated with the blades and air as one system. A rotating blade flow channel model was established to compute the 3D unsteady transient in air flow channel, and the forced responses of blade in different rotate speeds were calculated by importing the transient pneumatic load to the finite element structural computation. The results showed that the blade instability range was near the natural frequency under the unsteady condition. Thus, a feasible method was provided for the estimation and study of the dynamic responses of rotating blades in engineering. References | Related Articles | Metrics

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Algorithm of fast evaluation and derivation for the technique of NURBS direct interpolation Wang, Guo-Xun (1); Shu, Qi-Lin (2); Wang, Jun (3); Wang, Wan-Shan (1) 2012, 33 (7):  1021-1024.  DOI: - Abstract ( 810 )   HTML   PDF (151KB) ( 1759 )   In order to improve the real-time of the NURBS direct interpolation algorithm, a fast evaluation and derivation compute algorithm of the NURBS curve and surface was researched. According to the non-uniform B-spline derivation of de Boor-Cox algorithm, a fast recursive algorithm was put forward to derive the coefficient matrix of non-uniform B-spline basis function, which is based on the matrix representation of NURBS curve and surface. Compared with the traditional algorithms such as de Boor-Cox, the fast recursive algorithm has significant advantages in enhancing computation speeds, shorten interpolation cycle and improving interpolation real-time. The algorithm can be used to calculate the non-uniform B-spline curve and surface, except for the application in computer-aided geometric design. References | Related Articles | Metrics

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Analysis on geo-info-spectrum of landscape pattern evolvement of Qinhuangdao city Leng, Wen-Fang (1); Liu, Zhi-Guo (2); Xiao, Du-Ning (3); Wang, En-De (1) 2012, 33 (7):  1025-1029.  DOI: - Abstract ( 512 )   HTML   PDF (1276KB) ( 710 )   The temporal and spatial change of landscape pattern in Qinhuangdao city since the early 1990s was analyzed based on RS and GIS survey. The land use information was acquired by interpreting the TM image data of 1993, 2000 and 2008, and 6 landscape indices (the proportion of all patches (PP), average patch area (APA), average patch perimeter (APP), average perimeter-area ration (APAR), fractal dimension (FD) and aggregation index (AI)) were adopted to characterize the spatial pattern of landscape during these three periods. The transition matrix was used to analyze the varying characteristics of all landscape types. The result showed that, natural and semi-natural landscape types, such as forest, grass and water body, decreased, so did agriculture land, however, the dry-land increased because of the decreasing irrigated land. The increased land for construction because of the human's activities, such as construction of cities and roads, is shown to be the main driving force for the changing landscape pattern. References | Related Articles | Metrics

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Dispersion character of magnetic separation concentrate in direct reverse flotation for a refractory iron ore Luo, Xi-Mei (1); Yao, Jin (1); Sun, Chuan-Yao (2); Yin, Wan-Zhong (1) 2012, 33 (7):  1030-1033+1042.  DOI: - Abstract ( 492 )   HTML   PDF (1511KB) ( 751 )   A simple direct reverse flotation technology of magnetic separation concentrate for a refractory iron ore was introduced. The morphology and mineral composition of raw ore, concentrate and tailings were discussed by means of XRD, SEM and EDS, and the dispersion character of minerals was mainly analyzed, which provided theory foundation for direct reverse flotation technology of magnetic separation concentrate for carbonate-containing refractory iron ore. The results showed that the qualified iron concentrate can be obtained by adding dispersant; lots of fine useful iron minerals and gangue particles are easy to cover non-selectively on the surface of coarse iron minerals and gangue particles, which is the main reason of the refractory iron ore difficult to be separated. It has been comprehensively demonstrated that dispersant plays an important role in dispersing the particles, and hence, the selective separation of useful iron minerals from gangues occurs. References | Related Articles | Metrics

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Environmental load analysis of wind turbines based on life cycle assessment Gao, Cheng-Kang (1); Dong, Jia-Hua (2); Zhu, Wei-Guang (1); Wang, Wei (1) 2012, 33 (7):  1034-1037.  DOI: - Abstract ( 736 )   HTML   PDF (500KB) ( 1080 )   The life cycle assessment (LCA) was applied to analyze each stage of a wind turbine including manufacturing of raw materials and transportation, building, use and dismantling of the equipment, and environmental load of various stages was calculated respectively. The environmental load was described by indexes of global warm potentiality (GWP) and acidification potentiality(AP), and the wind turbine and a coal generator were compared and analyzed. Taken Wanghai Temple wind farm in Shenyang as a case study, the results showed that, during a life cycle of the wind turbine (average 20 years), the larger environmental load processes are the manufacture of raw materials and construction, operation and maintenance of power stations, and in contrast to a coal generator, the wind turbine can reduce 3.96 t standard coal, 9.77 t CO2, 0.050 t NOx and 0.02 t SO2 for a 10 MW·h, and its GWP and AP will be 1.08% and 3.12% of a coal generator, respectively. However, it destroyed a large number of ecological resources in construction process. Hence, the environmental protection measures will be further strengthened, and it is important to minimize the damage to ecological resources. References | Related Articles | Metrics

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Deformation properties of layered sandy foundation soil tested with static additional load Li, Chun (1); Zhu, Fu-Sheng (1); Zhang, Xue-Yuan (1) 2012, 33 (7):  1038-1042.  DOI: - Abstract ( 513 )   HTML   PDF (1796KB) ( 656 )   The whole variation and distribution of effective additional stress acted on the foundation base, tensile stress in reinforced bars in foundation concrete and vertical deformation of the foundation base were investigated via field monitoring. It is found that, the contribution of the effective stress increment of soils overlaid the foundation base to the settlement, which is influenced by dewatering of foundation pit, should not be neglected. Moreover, the compressive stress acted on foundation base can not be simply assumed as evenly distributed load, the resultant largest vertical deformation is not consistent with working point of the largest stress, and the settlement at the centre of foundation maybe not be the largest. Settlement located in different place is not usually uniform, and the largest settlement is only 14.22 mm; the tensile stress of reinforcing bars changed alternately with time, and the maximum tensile stress does not exceed about 22% of the allowable strength of reinforcing bars. Conclusions may offer a reference to the design of the large concrete footing and the layered sandy foundation base. References | Related Articles | Metrics

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Interval number density operator and its application Li, Wei-Wei (1); Yi, Ping-Tao (1); Guo, Ya-Jun (1) 2012, 33 (7):  1043-1046.  DOI: - Abstract ( 588 )   HTML   PDF (163KB) ( 866 )   Aiming at the uncertain multi-attribute decision making of interval numbers, the density operator was extended from exact values to interval numbers. First, the notion of interval attaching degree was introduced so as to cluster interval numbers, and the density weighting vector was determined by adopting a programming model. Then based on this, the interval number density middle (IDM) aggregation operator and its composite operators were defined. At last, one example was given to illustrate the application of this interval number density operator. By integrating the features of interval numbers, this method can further expand the theoretical system and application fields of density operators. References | Related Articles | Metrics

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Top managers' compensation contract and performance standard choice in different life-cycles Sun, Shi-Min (1); Gao, Li-Li (1); Wang, Ang (1); Zhao, Xi-Nan (1) 2012, 33 (7):  1047-1051.  DOI: - Abstract ( 503 )   HTML   PDF (180KB) ( 835 )   Based on 2008~2010 Shanghai A-share listed companies, the relationship between top managers' compensation and company performance at various life-cycle stages was tested by an empirical research. It was found that the choices of performance standards in designing top managers' compensation contract are different at various life-cycle stages. The companies in the initial and growing periods prefer to select performance standards with both financial and market modes, such as return rate on net assets and stock market value; those in the maturity period have preference for market mode performance standard, such as stock market value; those at the recession stage only pay attention to rate of cost reduction and adopt financial mode performance standard. What is more, the empirical research findings indicated that value mode performance standard is ignored in designing top managers' compensation contract, which leads to a comparatively lower value creation ability for China's listed companies. References | Related Articles | Metrics

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Study on the key factors of senior managers' compensation in high-tech companies Liu, Ye (1); Sun, Fan-Yun (1); Zeng, Li-Li (1); Zhang, Yu-Kun (1) 2012, 33 (7):  1052-1055.  DOI: - Abstract ( 338 )   HTML   PDF (148KB) ( 518 )   Based on the high-tech companies of Shanghai and Shenzhen Stock Markets in 2006~2008, an empirical research was conducted on the relationship among performance, governance mechanisms and senior managers' compensation by adopting the panel data. The results indicated that there is a significant positive correlation between enterprise performance and senior managers' compensation, whereas the proportion of independent directors is negatively related to senior managers' compensation. It was suggested that enterprise performance is still a key factor determining senior managers' compensation. Moreover, the governance mechanisms from independent directors of high-tech companies tend to solve the problem of so-called insider control, and thus lower the agency cost. References | Related Articles | Metrics

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An empirical research on long-term memory of returns and trading volumes of stock markets in China Yuan, Ying (1); Du, Le-Lu (2); Zhuang, Xin-Tian (1) 2012, 33 (7):  1056-1059+1064.  DOI: - Abstract ( 515 )   HTML   PDF (547KB) ( 602 )   From the perspectives of econometrics and statistics, the long-term memory of returns and trading volumes of stock markets in China was studied by adopting rescaled range analysis, modified rescaled range analysis, KPSS and Granger causality test, and the interrelationship between returns and trading volumes was studied as well. The results of rescaled range analysis and modified rescaled range analysis indicate that the Hurst exponents of return series and trading volume series are both greater than 0.5 and the Hurst exponents of trading volume series are significantly greater than those of return series. In addition, the KPSS statistics of return series and trading volume series are all significant for all lag orders, which suggests that returns and trading volumes of stock markets in China have a long-term memory, with the long-term memory of trading volumes being stronger than that of returns. Moreover, Granger-causality test proved that a relationship of mutual causality exists between returns and trading volumes. References | Related Articles | Metrics

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Lignin content and related characteristics of transgenic barley stems Sun, Cai-Xia (1); Wu, Xiao-Fei (1); Wang, Jie (1); Chen, Zhen-Hua (2) 2012, 33 (7):  1060-1064.  DOI: - Abstract ( 440 )   HTML   PDF (657KB) ( 671 )   Taking different transgenic barley as test materials for pot experiment, the lignin content, key enzyme activity, stem structure and Fourier transform infrared spectroscopy of different barley stems were studied to reveal the unintended changes related to lignin metabolism in transgenic barley. The results showed that the lignin content, parenchymal tissue, numbers of vascular bundles, guaiacyl lignin (G), syringyl lignin (S) and A(S)/A(G) of transgenic barley (T1, T2) stems had no significant changes in comparison with that of the wild type (WT) and non-transgenic barley (NT1). The unintended changes of the transgenic barley T1, such as the key enzyme activities of lignin metabolism (for PAL decreased by 66% and for POD increased significantly by 76%), the sclerenchymal tissue and the ρ-hydroxyphenyl lignin (H) ratio (decreased by 59%), may be mainly caused by somaclonal variation generated from tissue culture during genetic transformation. References | Related Articles | Metrics