Journal of Northeastern University(Natural Science)

Control of a Nonlinear Magnetic Levitation System Based RBF Neural Network

ZHAO Shi-tie， GAO Xian-wen， CHE Chang-jie

2014, 35 (12): 1673-1677. DOI: 10.12068/j.issn.1005-3026.2014.12.001

Abstract ( 770 )

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Magnetic levitation system is a typical nonlinear and uncertain system， because it must be combined with a controller which has good control performance to be applied in various occasions. The identified nonlinear magnetic levitation system using of the Radial Basis Function neural network(RBFNN)was proposed. The neural network adaptive state feedback controller and adaptive PID controller of magnet levitation system was designed based on the neural network adaptive control principle. Besides， a simulation of the system was proposed by using MATLAB， and the result showed that neural network adaptive controller had a good effect on this nonlinear system. In addition，this control system had a preferable stability and control property.

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Selection of Cerebral Arterial Input Function with DSC Imaging Based on k-means Cluster Analysis

YIN Jian-dong， SUN Hong-zan， YANG Jia-wen， GUO Qi-yong

2014, 35 (12): 1677-1681. DOI: 10.12068/j.issn.1005-3026.2014.12.002

Abstract ( 716 )

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The manual method for the detection of arterial input function(AIF)in cerebral perfusion based on DSC-MRI technique was not only time-consuming but also user-dependent， meanwhile， the accuracy and reproducibility were not very satisfactory. To solve this problem， a semi-automatic AIF detection method based on k-means cluster analysis is suggested. The pixels in the region of interest(ROI)were divided into several clusters and the mean curve of each cluster was calculated. A measure，［peak value /(time to peak× full width at half maximum)］， was calculated for each mean curve， and the one with the maximum measured value was used to determine the AIF. Twenty subjects were taken part in the research. By comparing with the result derived from the traditional manual method， the clinical feasibility was validated. The result demonstrated that the AIF obtained from the semi-automatic method based on k-means cluster analysis was superior to that based on traditional manual method. In conclusion， the semi-automatic selection of AIF based on the k-means cluster analysis can not only reduce the analysis time and observer dependence， but also improve the calculation accuracy and reliability.

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An Improved Algorithm for Exactly Eliminate the Decaying DC Component Error

WU Xian-gui， WANG An-na， WANG Hao

2014, 35 (12): 1682-1686. DOI: 10.12068/j.issn.1005-3026.2014.12.003

Abstract ( 825 )

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When the traditional full-cycle Fourier algorithm is directly used to process the power system fault signal including the decaying DC component， some errors will be produced. Thus， an improved Fourier algorithm which could eliminate the errors was proposed. This algorithm was based on the principle that integration of the input signal including the decaying DC component and summation of the sampled data were not zero in a full-cycle. This algorithm did not need addition of the sampled data and the approximation calculation in its derivation process， and could calculate the errors caused by the decaying DC component and its parameters. The errors caused by the decaying DC component could be eliminated from the results of the input fault signal. The simulation results showed that the parameters of fundamental frequency component and every harmonics can be accurately obtained， and the proposed algorithm can be used in power system on-line harmonic analysis.

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Research on Carrier Phase Tracking Error in Ultra-tightly Coupled GPS/INS Integration

SUN Xing-li， QIN Hong-lei， CONG Li

2014, 35 (12): 1687-1691. DOI: 10.12068/j.issn.1005-3026.2014.12.004

Abstract ( 776 )

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The design of carrier phase lock loop(PLL)is a key technology in the design of GPS receiver. The main error sources of PLL include phase jitter and dynamic stress error. With the increase of receiver platform dynamic， the larger dynamic stress error will lead to the loop loss lock. In order to adapt to the dynamic environment， the receiver usually use ultra-tightly coupled(UTC) GPS/INS integration with INS aided PLL tracking loops. Due to the aided information which the integration system provided may not be completely accurate， the tracking loop can reduce the dynamic stress error and will also introduce other measurement error sources. The PLL tracking error based on the INS estimation Doppler error was deduced in detail and two specific formulas were obtained. The simulations results showed that the PLL tracking error analysis were accurate on UTC system， which could provide reference for the optimal design PLL loop parameters.

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A Kind of Threshold Proxy Signature Scheme with Nonrepudiation Property

LIU Dan-ni， WANG Xing-wei， HUANG Min

2014, 35 (12): 1692-1696. DOI: 10.12068/j.issn.1005-3026.2014.12.005

Abstract ( 547 )

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To overcome the drawbacks， such as high computational complexity and heavy communication， in the present threshold proxy signature schemes， a nonrepudiable threshold proxy signature scheme was proposed. To improve the security，when a signer applies for public key certificate to the CA， the CA validates the signer′s private key associated with the signer′s public key by the method of zero-knowledge proof. To improve the efficiency， in the phase of proxy key generation， original signer only needs to calculate and broadcast a public proxy share to the proxy group， and the group members generate their own proxy keys concurrently. Comparing with the schemes that original signer generates proxy keys one by one for all the proxy members， the amount of calculation was greatly reduced by the proposed method. The security model of three types of adversaries was proposed. It was simulated that the adversaries forge the signature. The new scheme was proved to be secure by the simulation process.

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A Measure Model of Similarity for Finding the Best Coach

CHEN Da-li， SHEN Yan-tao， XIE Bing-zhu， MA Ying-yi

2014, 35 (12): 1697-1700. DOI: 10.12068/j.issn.1005-3026.2014.12.006

Abstract ( 828 )

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A similarity calculation method was applied to establish the mathematical model to select the best coach. The index vector was defined to assess the coaching ability of coacher. The improved method was given to reduce the impact caused by the factor of time. The variance analysis was used to assess the impact caused by the gender. Based on this analysis，the whitening approach was used to remove the impact caused by the gender. To apply cosine similarity to select the best coach， criteria collected based on experience should be transferred as vectors， then compared with the idealistic coach. Many experiment results demonstrated the validity of the proposed method.

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Social-Aware Node Mobile Trajectory Prediction Algorithm in Opportunistic Cognitive Networks

LI Jie， XIA Xing-you， WANG Xing-wei， ZHOU Yan

2014, 35 (12): 1701-1705. DOI: 10.12068/j.issn.1005-3026.2014.12.007

Abstract ( 772 )

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Mobile node trajectory prediction is a basis for effective data collection and data dissemination in opportunistic cognitive networks. A social-aware node mobile trajectory prediction algorithm was proposed， in which the location of other nodes were used to update the prediction results based on the 1-order Markov model， and the accuracy of the prediction model was improved by sparse of state transition matrix. Finally， the feasibility of prediction model was verified based on the UCSD WTD dataset. The results showed that the location prediction model based on social relationship could get better accuracy than that of the 1-order Markov prediction model. Therefore， the algorithm has high value in practical applications.

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Primary User Signal Recognition Algorithm based on Random Forest in Cognitive Network

WANG Xin， WANG Jin-kuan， LIU Zhi-gang， HU Xi

2014, 35 (12): 1706-1709. DOI: 10.12068/j.issn.1005-3026.2014.12.008

Abstract ( 934 )

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A novel approach to signal recognition based on random forests， which uses signal cyclic spectrum feature parameters as sample parameters， was introduced to solve the problem of the low accuracy of the primary user signal type identification in low signal-to-noise ratio(SNR). By utilizing the proposed algorithm， the detecting signal types were identified by the trained random forests. The errors using artificial neural network(ANN)and support vector machine(SVM) were restrained. The accuracy of signal type identification was improved in low SNR and effective signal detection and recognition was achieved to different modulated signal. Simulations showed the validity and superiority of the proposed algorithm.

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Microstructure of Laser Cladding Multi-layer Nb-Si-Ti

LIANG Jing， CHEN Sui-yuan， LIU Chang-sheng， CHEN Wei

2014, 35 (12): 1710-1714. DOI: 10.12068/j.issn.1005-3026.2014.12.009

Abstract ( 795 )

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The microstructure and composition design of the niobium silicide based composites which prepared by direct laser fabrication based on multi-layer laser cladding through optimizing laser scanning parameters and adjusting the composition ratio of the mixed element powders were investigated. Element powders mixture Nb-18Si-24Ti(at.%)was prepasted on a substrate of Ti-6Al-4V and scanned by a 500W pulsed Nd:YAG laser. Four-layer specimens were fabricated under the optimized laser processing parameters with electric current of 225A， laser scanning speed of 3.0mm/s， pulsed frequency of 15Hz， defocus length of 15mm. Microstructures and phases of the prepared specimens were analyzed by OM， SEM and XRD， respectively. Results showed that Nb₅Si₃， Nb₃Si and Nb_ss are formed in the multilayer laser cladding coatings. With the increase of the number of layers， the Nb and Si contents increase gradually， tiny dendrites are found in the layer near the substrate while the top layer contain island-shape grey phases distributed in the continuous white phases.

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Controlling the Biodegradation Rate of Mg-Zn-Sr Alloy Using Biomimetic Coating

ZHANG Ya-jing， WU Qin， ZUO Li-jing， YIN Wen-ya

2014, 35 (12): 1715-1718. DOI: 10.12068/j.issn.1005-3026.2014.12.010

Abstract ( 517 )

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Magnesium alloy has attracted the attention of the biomaterials community as a potential biodegradable metallic candidate for stents and orthopedic applications. The high corrosion rate of magnesium alloy confines their application in clinical. Therefore， it′s one of the main approaches to develop Mg-based biomaterials with good corrosion resistance and high strength for biomedical engineering. The apatite coatings were deposited on matrix through biomimetic method. The coating was characterized by XRD and SEM. The degradation rates of the samples without and with hydroxyaptite coating were researched in the simulated body fluid(SBF). The results showed that surface modification improves the corrosion resistance. The degradation rate of the Mg-Zn-Sr alloy with coating was slower than that of the alloy without coating on the surface.

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Research on Models of Power Production in Integrated Iron and Steel Factory

LIU Jing-yu， CHANG Yong

2014, 35 (12): 1719-1722. DOI: 10.12068/j.issn.1005-3026.2014.12.011

Abstract ( 585 )

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Electricity is an important energy in the production of iron & steel factory， which plays a decisive role in the whole process. This paper presents four kinds of models of steam generation technologies in integrated iron and steel industries. Energy inputs， electricity outputs， recovered waste heat efficiencies of boilers， steam turbines， gas turbines and coal-fired of the models were analyzed by using input-output method. Electric conversion， waste heat recovery and overall conversion efficiencies were compared with the actual data of three typical iron and steel enterprises. The models were discussed. And it is found that these established models have important guiding significance for power production in iron and steel enterprise.

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Design of Transformer for Ultra-High-Power Electric Arc Furnace

HOU Dong， JIANG Zhou-hua， GONG Wei， YIN Zhi-xiang

2014, 35 (12): 1722-1726. DOI: 10.12068/j.issn.1005-3026.2014.12.012

Abstract ( 1089 )

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A new design method for high-impedance electric arc furnace transformer voltages and rated current is put forward. After the “reactor short-circuit”， in order to ensure electrical efficiency by maintaining the arc voltage at the peak value in foaming slag， and to make full use of the transformer capacity， the stepped voltage and rated current of the transformer should be properly designed. The design principle for stepped voltage and rated current is established considering the constraint conditions of foaming slag thickness，power factor and transformer capacity， which will increase the transformer utilization and arc power， and cut down the melting time. At the same time，the designs of the maximum and minimum secondary voltages and transformer capacity are introduced. The results of analyzing the theoretical operation and design parameters of a 80 t high-impedance arc furnace show that the optimum stepped voltage is 734V. Above 734V， the limiting factor of increasing arc power is the rated current.

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Numerical Simulation on Behavior of Metal Jet in the Mold with Static Magnetic Field

DENG An-yuan， XU Lin， WANG En-gang， HE Ji-cheng

2014, 35 (12): 1727-1732. DOI: 10.12068/j.issn.1005-3026.2014.12.013

Abstract ( 714 )

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Using ANSYS CFX software and considering the effect of static magnetic field， the behavior of metal jet out from submerged nozzle in continuous casting mold is investigated. With various casting parameters， the variation law of level fluctuation index(F value)and the effect of jet characteristics on the impact strength of jet against the mold wall are all analyzed. The results show that the nozzle jet flow has an expansion feature. Under the static magnetic field， with the magnetic flux density increasing， the F value， metal jet size and impact strength against the mold wide face increase; with the slab thickness increasing， the F value and metal jet size increase， but the impact strength against the mold wide face decreases; with the jet angle increasing， the F value and impact strength against the mold wide face increase. In the continuous casting process with static magnetic field， the F value is not the only control index， and the influence of metal jet expansion on the impact strength against the mold wall should also be considered， i.e. different slab thicknesses and jet angles should have appropriate control variables.

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Unsteady Fluctuation Behavior of Slag-Metal Interface in a Slab Continuous Casting Mold

LIU Zhong-qiu， QI Feng-sheng， LI Bao-kuan， JIANG Mao-fa

2014, 35 (12): 1733-1737. DOI: 10.12068/j.issn.1005-3026.2014.12.014

Abstract ( 780 )

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The unsteady fluctuation behavior of the slag-metal interface in a slab continuous casting mold was studied using the volume of fluid(VOF)method. The morphology of the meniscus was simulated using the geometric reconstruction scheme. The effects of casting speed， immersion depth and port angle of submerged entry nozzle(SEN) on the interface fluctuation in the mold were studied. The results show that the interface fluctuation is ever changing with time. The fluctuation is small and increases with time at the beginning of the casting. After attaining dynamic steady state， serrated fluctuation phenomenon appears around the SEN. The reason for the serrated fluctuation is the existence of vortices. The fluctuation increases with increasing the casting speed， and decreases with increasing the immersion depth and port angle of the SEN.

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Thermodynamic Analysis of Phase Transition in Stainless Steel Slag During Solidification

CAO Long-hu， FENG Sheng-ke， LIU Cheng-jun， JIANG Mao-fa

2014, 35 (12): 1738-1742. DOI: 10.12068/j.issn.1005-3026.2014.12.015

Abstract ( 704 )

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The phase transition in stainless steel slag during solidification was studied with the thermodynamic software of FactSage 6.2. The results show that the temperature for merwinite and di-calcium silicate to precipitate can be decreased to lower values and the formation of melilite was accelerated with decreasing the basicity and increasing the Al₂O₃ content of the slag. The Cr content in the spinel phase increases obviously with decreasing the slag basicity. When the basicity decreased from 1.6 to 1.0， the Cr content in the spinel phase increased from 24.93% to 48.27%， thus leading to lower chromium content in liquid slag during solidification. When the Al₂O₃ content increased to 10% in the slag，the Al₂O₃ favored the precipitation of spinel phase. The chromium bounded in spinel phase was gradually replaced by aluminum with the lowering of temperature， and the Cr content in the spinel phase decreased from 30.39%(1500℃) to 13.88%(1300℃).

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Investigation on Effect of MgO on Reduction Metallurgical Properties of Iron Ore Pellet

GAO Qiang-jian， SHEN Feng-man， ZHENG Hai-yan， WEI Guo

2014, 35 (12): 1742-1745. DOI: 10.12068/j.issn.1005-3026.2014.12.016

Abstract ( 983 )

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The effect of MgO on reduction metallurgical properties of pellets were investigated， such as low-temperature reduction degradation index(RDI)， reduction index(RI)and reduction swelling index(RSI). The results show that， with the addition of MgO-bearing additive from 0 to 2.0% in pelletizing， the RDI and RSI decrease gradually， and the value of RDI and RSI decrease by 6.46% and 6.21% respectively， which means that the reduction degradation phenomenon and reduction swelling phenomenon are inhibited. The RI of pellets increased by 4.66% with the addition of MgO bearing additive from 0 to 2.0% in pellets， and therefore the addition of MgO is favorable to improve the reduction metallurgical properties of pellets. Based on the pore space analysis and mineral composition analysis of different MgO-bearing pellets， the reasons for the variation of metallurgical properties of pellets were clarified.

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Recovery of Valuable Components from Spent Pot-Lining of Aluminium Electrolytic Reduction Cells

CAO Xiao-zhou， SHI Yuan-yuan， ZHAO Shuang， XUE Xiang-xin

2014, 35 (12): 1746-1749. DOI: 10.12068/j.issn.1005-3026.2014.12.017

Abstract ( 839 )

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Spent pot-lining(SPL)of aluminium electrolytic reduction cells is currently the largest hazardous solid waste with high fluoride content in aluminium industry， which pollutes the surrounding environment seriously. Fluoride and carbon from SPL were recovered by water wash， chemical leach and calcination process using Al₂(SO₄)₃·18H₂O solutions. The results show that the appropriate leaching conditions were time of 24h at 25℃， the recovery rate of carbon is 88% from SPL， and the carbon purity increases from 61.3% to 89.6%. The effects of time， temperature and pH value of solution on recovery rate of fluorine were investigated. Fluoride can be precipitated as Al₂((OH)_0.46F_0.54)₆H₂O and Na₅Al₃F₁₄. The appropriate conditions of fluoride recovery were temperature of 90℃， pH value of 5.5 and time of 180min. The maximum fluorine recovery rate is 99.7%. The main products were AlF₃ and Na₅Al₃F₁₄ after calcination.

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Effects of Surfactant Tween 80 on the Bio-Leaching of Cobalt Concentrate

SONG Yan， YANG Hong-ying， TONG Lin-lin

2014, 35 (12): 1750-1753. DOI: 10.12068/j.issn.1005-3026.2014.12.018

Abstract ( 730 )

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The cobalt concentrate from Zambia were studied. Bacteria used in the leaching was ZY101， a kind of mixed bacteria which can grow normally in the system containing 30 g·L^-1 cobalt after a long time of domestication. During leaching of cobalt concentrate， the effects of surfactant Tween 80 were evaluated by measuring the pH value of solution， the electric potential value of solution， the density of Fe²⁺， the density of bacteria cell in solution and the rate of cobalt leached. The results showed that Tween 80 can improve the leaching of the cobalt concentrate and the optimal dosage is 0.01%(volume concentration). After leaching for 15 days， the rate of cobalt leached reaches 93.25%. Compared with the system of bioleaching solution without Tween 80， the rate of cobalt leached increases by 62%. During the bio-leaching of Zambian cobalt concentrate， the addition of Tween 80 exhibits good catalytic effect.

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Synthesis and Characterization of Azobenzene Liquid Crystalline Polymers Containing Cholesteryl Groups

YAO Dan-shu， DUAN Zhi-juan， ZHANG Zhen， MENG Fan-bao

2014, 35 (12): 1754-1757. DOI: 10.12068/j.issn.1005-3026.2014.12.019

Abstract ( 652 )

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The azo monomer 4-(allyloxybenzoyloxy)azobenzene-4′-ethyl formate(M)and chiral monomer 4-(allyloxybenzoyloxy)isopropionate cholesteryl(N)were grafted onto the backbone of polymethylhydrosiloxane. A new kind of azobenzene liquid crystalline polymers(PY₁~PY₆)containing cholesteryl groups was prepared. Their chemical structures were confirmed by FT-IR and ¹HNMR spectra， and mesomorphic properties， phase behavior and thermal stability were investigated by DSC， POM and TG. The results showed that PY₁~PY₆ are thermotropic cholesteric liquid crystal and display Grandjean texture. With the increasing content of M， t_g ascends after a decline， but t_i descends slowly. The temperatures when 5% weight loss occurred are higher than 290℃ and the mesomorphic temperature ranges are 162~189℃， which reveal that PY₁~PY₆ have a high thermal stability and remarkable liquid crystal properties.

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Simulation Analysis of Ground Surface Residual Stress with Thermal-Mechanical Coupling Principle

ZHANG Xiu-ming， LIU Li-juan， XIU Shi-chao， BAI Bin

2014, 35 (12): 1758-1762. DOI: 10.12068/j.issn.1005-3026.2014.12.020

Abstract ( 625 )

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In order to research the distribution characteristics of workpiece grinding surface residual stress， grinding temperature field should be analyzed firstly. The influence of different grinding parameters on grinding zone temperature field was analyzed by using ANSYS through the established mathematical model of temperature field and heat transfer. The simulation results show that the influence of the cutting depth on the highest temperature is the largest. Using APDL program combined with the grinding force produced in grinding process， the thermal-mechanical coupling field of the grinding surface was simulated and analyzed. The size and distribution state of the residual stress were obtained and the thermal-mechanical’s influence on the residual stress was discussed and uncovered. Finally， the correctness of the simulation result was verified through the comparison of residual stress test results and simulation results.

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Profile Curves of Roller Forming Screw Compressor Driven Rotor with Fixed Cross Rolling

YANG Guang， ZHANG Kang-sheng， HU Zheng-huan

2014, 35 (12): 1763-1767. DOI: 10.12068/j.issn.1005-3026.2014.12.021

Abstract ( 527 )

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Fixed cross rolling is an improved process to achieve the near-net forming of the screw rotor with big-spiral teeth， and the key of the process is to couple with the profile curves. In the rolling process， the meshing relationship between the roller and the workpiece is different from the original between the screw rotors， therefore， couple profile of the roller and the workpiece need to be redesigned to accommodate to variable rolling forming. Taking a driven rotor as an example， the geometric model of the coupled profile curves of the roller and the driven rotor propitious to fixed cross rolling was rebuilt by means of envelope analysis. Then，using matrix theory， the corresponding parametric equations of the coupled profile curves were established to realize the parametric design of the roller profile and increase technology universality. Finally， the dynamic simulation results verified the correctness of the previous parametric equations and without the interference phenomenon.

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Performance Analysis of Wind Turbine Blade Based on Parametric Modeling

CHEN Jin， MA Jin-cheng， GUO Xiao-feng， SUN Zhen-ye

2014, 35 (12): 1768-1772. DOI: 10.12068/j.issn.1005-3026.2014.12.022

Abstract ( 702 )

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In view of the existing 850kW wind turbine blade， the material， structure and layer condition were analyzed， compared to the traditional blade finite element model. The chord length and twist which mainly described the structure of blade were expressed by using piecewise function expression form， and the parameterized geometric model of wind turbine blade was found through MATLAB and ANSYS to accomplished secondary development. The ultimate load of every section was solved by BALDED which basing on blade element momentum theory， and the increasing load was applied on the every part of blade. The first three waves and shimmy frequencies and the first torsion frequency were obtained through dynamic analysis， which comparing with the measured natural frequencies. The blade working outside the resonance region was proved. The distances of wave and stress distribution of key parts were received by static force analysis， and the wing surface was strength checked through maximum stress criteria and Tsai-Wu criteria(other parts in the same way). It showed that the blade could keep operate safely under limit state. The research describes the main mechanics performances of blade， and it lays the foundation for the blade to be optimized further.

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Numerical Simulation of Cutting Force Based on GA and DEFORM in Turning Ceramics

MA Lian-jie， LI Chen， CAO Xiao-bing， GONG Ya-dong

2014, 35 (12): 1773-1777. DOI: 10.12068/j.issn.1005-3026.2014.12.023

Abstract ( 696 )

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Through the modification of constitutive model， finite element simulation， optimization of genetic algorithm， numerical simulations and experimental， the law of cutting force was studied in turning ceramics. Based on finite element simulation， chip formation mechanism indicates the chip was continuous layered applying classical Johnson-Cook model， and it did not accord with cutting experiment. After improving the model， the chip was crack-chip in the finite element simulation， and it was applicable for cutting ceramics. Based on least squares method， the monadic regression was carried out according to simulation data of simple single factor， and the analytical equation was obtained on cutting force with changing a single parameter. Correlation coefficient test indicated that the precision of improved model was high. The multivariate model of cutting force was established by genetic optimization algorithm. The multivariate model was verified by single factor and orthogonal tests， and the results indicated the model was accurate to present the law of cutting force and reliable.

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Effect of the Process Parameters on Surface Spiral in Cross Wedge Rolling of 4Cr9Si2

HUANG Jiang-hua， LIU Jin-ping， WANG Bao-yu， HU Zheng-huan

2014, 35 (12): 1778-1782. DOI: 10.12068/j.issn.1005-3026.2014.12.024

Abstract ( 605 )

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Cross wedge rolling process of 4Cr9Si2 was simulated by DEFORM software， and the influence of process parameters on surface spiral on cross wedge rolling of 4Cr9Si2 was analyzed. The results showed that the surface spiral was resulted from the variation of stress state which was generated in the process of rolling. As the forming angle increased， the depth of surface spiral increased. The surface spiral decreased after increasing of wedge tip fillet. Effect of stretching angle on the surface spiral was not obvious. When the area reduction decreased， plastic deformation was smaller and the surface spiral reduced. These simulated results were verified by experiments. The process parameters for a certain type of valve were determined to be α=32°，β=7.5°， R=12mm， when area reduction is 70.84%， and valves without surface spiral were experimentally achieved.

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Surface Modification of Nesquehonite Whiskers with Stearic Acid

WANG Yu-lian， YIN Wan-zhong， WANG Lei， YAO Jin

2014, 35 (12): 1783-1786. DOI: 10.12068/j.issn.1005-3026.2014.12.025

Abstract ( 665 )

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Surface modification of the nesquehonite whiskers with stearic acid was studied， surface modification effect of stearic acid dosage， slurry concentration and modification time was investigated on the nesquehonite whiskers. Modified nesquehonite whiskers were characterized with contact angle， activation index， SEM， TG-DSC and FTIR. The results indicated that the best process condition was modifier dosage of 5%， slurry concentration of 5% and modification time of 60min. Under the optimum condition， contact angle of modified product is 130° and activation index is 1.000. There is no distinct effect of surface modification on the thermal decomposition of nesquehonite whiskers. The interlinkage between the stearic acid and nesquehonite whiskers is mainly caused by hydrophobic magnesium stearate films formed by magnesium ions and carboxyl groups.

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Influence of Metal Ions in Pulp on Floatability of Kyanite Minerals

ZHANG Jin-xia， FENG Ya-li， NIU Fu-sheng

2014, 35 (12): 1787-1791. DOI: 10.12068/j.issn.1005-3026.2014.12.026

Abstract ( 621 )

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The influences of metal ions on floatability of kyanite， quartz and biotite were studied by flotation tests. The test results showed that Ca²⁺ and Mg²⁺ have significant activation of kyanite flotation， while Al³⁺ and Fe³⁺ have strong depression of quartz and kyanite flotation. The analysis results of flotation solution chemistry showed that the flotation of kyanite and quartz are depressed intensively owing to the generation of corresponding hydroxide precipitations of A1³⁺ and Fe³⁺. The electrostatic interaction is contributing to strengthen the adsorption of minerals and dodecylamine when the zeta potential of kyanite shift markedly towards negative direction in the presence of corresponding hydroxy complex of Ca²⁺ and Mg²⁺， so flotation of kyanite can be activated. According to particle distribution theory in Boltzmann vector field， activation or depression mechanism of metal ions were analyzed by calculating amine ion(RNH⁺₃) concentration in liquid phase interior， the interface layer and their ratio under different pH value conditions before and after Fe⁺₃ effect on minerals.

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Chaos Identification of Precipitation Time Series and Subdivision Based on the 0-1 Test

WEI Run-chu， XIAO Chang-lai， ZHANG Yu-qing， LIANG Xiu-juan

2014, 35 (12): 1792-1796. DOI: 10.12068/j.issn.1005-3026.2014.12.027

Abstract ( 815 )

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The 0-1 test is a new binary test approach for distinguishing chaotic dynamics， which applies directly to time series data. It was proved to be an effective test method after test for chaos of Chebyshev map. The 0-1 test was carried out on monthly precipitation time series tested to be stationary from 1958 to 2011 of 106 meteorologic stations in Northeast China. It is showed that monthly precipitation time series of all stations are chaotic， further more， the spatial interpolation of asymptotic growth rate K of mean square displacement with time shows significant spatial variability， that is， the whole study area can be divided into four sub-regions， eastern district with the highest K values， western and northern districts with the second high， south-central district with the lowest and a local area with relatively low K value in the northeastern of Inner Mongolia and northwestern Heilongjiang， which is in good agreement with the precipitation geographical distribution features and changes type of Northeast China. The results show that 0-1 test method has the characteristics to reflect the degree of chaos for data series.

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Holistic Optimization of Production Planning Elements and Its Application for Open-Pit Mine

WANG Qing， GU Xiao-wei， XU Xiao-chuan， LIU Jian-ping

2014, 35 (12): 1796-1800. DOI: 10.12068/j.issn.1005-3026.2014.12.028

Abstract ( 706 )

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Based on the biggest stripping ratio pit， cone elimination method was used to gradually remove the parts which satisfy the increment size while the average grade of removed parts was lowest. In this way， a sequence of geologically optimum pits and push-backs could be obtained. Dynamic programming was used to generate optimum production planning of each pit， based on which the largest NPV was chosen as optimum pit and the best mining path was further chosen as the optimal production design， thus realizing the simultaneous optimization of the pit and production design. The algorithm was programmed and applied on engineering project. The results show that， under the condition of costs and prices remaining the same， ore and waste quantities of the best plan in the holistic optimization are less than 42.4% of the biggest profit pit while the NPV of the former is 17.0% above the latter. As costs and prices rising by 2% and 3.5%， respectively， ore and waste quantities of the best plan in the holistic optimization are more than 55.0% of the biggest profit pit while the NPV of the former is 6.0% above the latter.

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A Decision-Making Method for Outpatient Appointment Based on Prospect Theory

CAO Ping-ping， LI Ming-yang， LI Xu

2014, 35 (12): 1801-1804. DOI: 10.12068/j.issn.1005-3026.2014.12.029

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For the outpatient appointment decision problem in which patients′ preferences for service time periods and doctors are given， a decision-making method for outpatient appointment based on prospect theory was proposed. Firstly， loss matrix and revenue matrix were given based on patients′ preferences for doctors， and then the standardized property matrix for doctors was proposed according to prospect theory and matrix standardized method; similarly， loss matrix and revenue matrix were given based on patients′ preferences for service time periods， and then the standardized property matrix for service time periods was proposed; further，by establishing the integrated property matrix of patients served by doctors in each time period， an optimization model that aims for maximizing the sum of patients′ integrated property values was developed， and the appointment decision result could be obtained by solving the model. Finally， an example was given to illustrate the use of the proposed method.

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