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Journal of Jiangsu University(Natural Science Eidtion)

	2013 Vol.34 Issue.1 Published 2013-01-10

	Article

Article

	1	Simulation of aerodynamic noise from centrifugal fan of HVAC in automobile
		Kang Qiang, Zuo Shu-Guang, Han Hui-Jun
		Transforming the Lighthill equation into a variational form, the aerodynamic noise of centrifugal fan of HVAC in automobile was numerically calculated by finite element method with the consideration of the reflection and refraction of sound transmission in complex solid surfaces. Simplifying the free space Green function as a free space problem for far field sound radiation， the aerodynamic noise was also calculated by integration method. The unsteady flow inside centrifugal fan was calculated by DES model to show that the major noise sources were from blade pressure surfaces and the front and rear parts of tongue according to the analyses of the contours of vorticity, sound power and pressure fluctuation at different locations. Two aeroacoustic finite element models were established to calculate the radiating noise of centrifugal fan with and without consideration of volute. The comparison results show that the aeroacoustic calculation results based on finite element method have good consistency with reality, while the simplification of integral solution by Green function results in large error.
		2013 Vol. 34 (1): 1-6 [Abstract] ( 1787 ) [HTML 1KB] [ PDF 2713KB] ( 3172 )

	7	Adsorption properties of carbonized micron wood fiber filter for nanoparticles emitted by engine
		GUO Xiu-Rong, DU Dan-Feng, MA Yan
		To effectively collect the nanosized particulate material（nanoparticles ) emitted by diesel, a diesel particulate filter(DPF) was prepared with carbonized micron wood fiber(CMWF) material. The characteristics of CMWF filter and particulate material(PM) were analyzed to simulate the absorption process of nanoparticles in CMWF filter based on grand canonical ensemble Monte Carlo method(GCEMC). The numerical simulation result was verified by DPF performance test bench. The results show that when the pressure ranges from 102.5 kPa to 125.0 kPa at the temperature of 470 K, the adsorption number densities of nanoparticles in CMWF filter obtained by GCEMC and test are 6.28×107 cm-3 and 5.60×107 cm-3, respectively. The simulated results are in good consistency with the experimental results. The simulation method is suitable to investigate the adsorption process of nonoparticles in CMWF filter.
		2013 Vol. 34 (1): 7-12 [Abstract] ( 1529 ) [HTML 1KB] [ PDF 2015KB] ( 2459 )

	13	Attitude control of automobile based on inflation/deflation of air spring
		XIA Jing-Jing
		According to the automobile working characteristics and the air spring inflation/deflation performance, the control system and strategies of the automobile running attitude were proposed. In order to improve the vehicle lateral stability, the controller of air suspension stiffness adjustability was designed. Under the dangerous condition of automobile roll, the controller can adjust the air suspension stiffness to improve the vehicle lateral stability and reduce the occurrence of side tumbling crash accidents. To meet the requirement of working equipment under normal working conditions, the controller of body horizontal position adjustment was designed to control the horizontal position of vehicle body. The simulation experiment was conducted with the vehicle speed of 80 km·h-1 and steering wheel angle of 200°. The rigidity of left air suspension was raised by 12.5% with decreased rigidity of 13.3% for right air suspension, while the roll angle was stable at 4.1°. The results show that the vehicles running attitude can be well controlled by the proposed control system.
		2013 Vol. 34 (1): 13-16 [Abstract] ( 1233 ) [HTML 1KB] [ PDF 1604KB] ( 2224 )

	17	Application of pedal stroke simulator in brake-by-wire-system
		SONG Chuan-Xue, ZHENG Zhu-An, JIN Li-Qiang, PENG Si-Lun, WANG Jian-Feng, XIAO Feng
		To improve the braking comfort, the brake pedal feel was simulated by pedal stroke simulator with the consideration of brake pedal feel as core part of brake-by-wire system and direct-relationship to driving comfort and safe travel performance of vehicle. The brake-by-wire system with pedal stroke simulator was analyzed and compared with the traditional braking system. The pedal stroke simulator model was established by AMESim software, and a single neuron adaptive intelligent PID control strategy of pedal stroke simulator was designed by MATLAB/Simulink software. The basic parameters of bench test of traditional vehicle braking system was set to be simulated for validation. The simulation results show that the pedal stroke simulator and the control strategy can meet the performance requirements of traditional braking system with improved braking comfort.
		2013 Vol. 34 (1): 17-22 [Abstract] ( 2575 ) [HTML 1KB] [ PDF 2518KB] ( 3036 )

	23	Generation mechanism of NOx for biodiesel combustion process
		MEI De-Qing, ZHANG Yong-Tao, YUAN Yin-Nan
		To investigate the generation mechanism of NOx for biodiesel combustion, the contrast test of diesel engine fueled with biodiesel and petrolic diesel was conducted. The heat release rate based on measured cylinder pressure indicator diagraph was calculated. A NO formation model of Zeldovich mechanism was established based on the real heat release rate and chemical component equilibrium of fuel combustion. The effects of combustion features of heat release moment, bulk gas temperature and oxygen concentration on NO formation were also analyzed to explain the reason of much NOx generation in biodiesel engine. The results show that the bulk gas temperature in cylinder of biodiesel engine is decreased, while the ignition start of biodiesel engine is early to reach the trigger temperature of NO formation. The oxygen concentration at combustion area is high due to the oxygenated property of biodiesel. The NOx emission from biodiesel engine is more than that from diesel engine.
		2013 Vol. 34 (1): 23-27 [Abstract] ( 3198 ) [HTML 1KB] [ PDF 1834KB] ( 4375 )

	28	Optimal design of centrifugal pump with tilt volutebased on CFD
		YANG Min-Guan, ZHANG Ning, LI Zhong, GAO Bo
		To achieve high efficiency and low pressure pulsation, the slant angle of tilt volute and clearance between impeller and volute were controlled. A centrifugal pump with tilt volute of specific speed 130 was simulated by Fluent software at the same boundary conditions. The results show that when clearance rate keeps constant, the hydraulic efficiency reaches maximum at slant angle of 15°. The hydraulic efficiency is increased with the increasing of clearance rate with maximal value at clearance of 0.308. FFT(Fast Fourier Transform Algorithm) was adopted to transform timedomain pressure signals into frequencydomain pressure signals. The magnitude of pressure pulsation at fBP obtains minimum value at slant angle of 15°. The amplitude of pressure pulsation at fBP is decreased with the increasing of clearance rate. The clearance rate is suggested in the range from 0.134 to 0.192 because the clearance rate is limited by radial dimension.
		2013 Vol. 34 (1): 28-32 [Abstract] ( 1785 ) [HTML 1KB] [ PDF 2100KB] ( 2242 )

	33	Hydrodynamic characteristics of cylindrical semi-submersible offshore oil platform
		ZHANG Yong-Kang, SHEN Han, DAI Feng-Ze, NI Tao, ZHUANG Jian-Jun
		The models of SEVAN 650 and GVA 7500 were established in Pro/E software. The proposed models were imported into the Hydrodynamic Diffraction module of ANSYS Workbench software to calculate the response amplitude operators of each platform in storm environment of South China Sea. The hydrodynamic characteristics of the two platforms in the storm environment were compared by the characteristic curves of heave, roll and pitch. The results show that SEVAN 650 has better crude oil storage capacity and deck variable load bearing capacity than those of GVA 7500, which indicates that SEVAN 650 has better anti-dumping capacity than that of GVA 7500 in storm environment. However, the heave response amplitude operator of SEVAN 650 in storm environment should be further reduced.
		2013 Vol. 34 (1): 33-37 [Abstract] ( 2164 ) [HTML 1KB] [ PDF 2594KB] ( 2998 )

	38	Total volatile basic nitrogen prediction models of Pampus argenteus based on olfaction visualization detection technique
		HUANG Xing-Yi, JIANG Fei-Yan, MU Li-Jun, SUN Zong-Bao
		TVB-N contents of Pampus argenteus samples stored in refrigerator at constant temperature of 4 ℃ were measured by semimicro-fixation of nitrogen method. The headspace volatile gases of Pampus argenteus samples were extracted by olfaction visualization detection system. The RGB value changes of the colorimetric sensor array before and after exposure to the headspace gas were obtained as the sensor array responses. Partial least squares(PLS) model and genetic algorithm-partial least square(GA-PLS) model were established and compared. The GA-PLS model is good with the correlation coefficient (RP) between actual value and predicted TVB-N content of 0.851 7 for the validation dataset. There exists a good correlation between the colorimetric sensor array responses and TVB-N content. The olfaction visua-lization detection technique can be used as a rapid way to predict TVB-N content and to evaluate fish freshness with non-destructive test.
		2013 Vol. 34 (1): 38-43 [Abstract] ( 1767 ) [HTML 1KB] [ PDF 1846KB] ( 1828 )

	44	Detection of beef TVB-N by visible and near-infrared spectroscopy combined with variable selection method
		MA Shi-Bang, PENG Yan-Kun, XU Yang, TANG Xiu-Ying, TIAN Xiao-Yu
		To realize rapid and non-destructive detection of total volatile basic nitrogen(TVB-N) content of fresh beef with improved detection accuracy throughout the storage period at 4 ℃, a laboratory visible and near-infrared spectroscopy system was established to collect beef samples reflectance spectra between 400 and 1 700 nm. The beef samples were stored at 4 ℃ for 1 to 17 days. Multiplication scatter correction (MSC), first derivative (FD), Szvitzky-Golay(SG) smoothing method were used as pretreatment method for raw sample spectra. Combined with the effective wavelength variables extracted by uninformative variable elimination(UVE) and successive projections algorithm(SPA)， the least square-support vector machine(LS-SVM) was proposed to predict beef TVB-N content. The results show that the SG is the best pretreatment method with reduced input variables by 99.5% for UVE and SPA, and the proposed LS-SVM has good performance with Rv of 0.925 and Sc of 4.615 mg?(100 g)-1，respectively.
		2013 Vol. 34 (1): 44-48 [Abstract] ( 2197 ) [HTML 1KB] [ PDF 2240KB] ( 2146 )

	49	Spectral quantitative model optimization by modified successive projection algorithm
		HAO Yong, SUN Xu-Dong, WANG Hao
		The raw and wavelet transform(WT) spectra of wine and apple were extracted by modified successive projection algorithm (MSPA).The quantitative models of alcohol and soluble solid contents (SSC) were established by partial least squares (PLS). Root mean square error of prediction(RMSEP), correlation coefficient of prediction (Rv) and akaike information criterion（AIC）were used to evaluate models. The results show that the simplized analysis models of alcohol and SSC determinations can be realized by WT-MSPA-PLS method. For alcohol model, RMSEP， AIC and modeling variables are reduced form 0.178, 4 085.60 and 2 073 to 0.139, -1.06 and 34, and Rv is improved from 0.963 to 0.976. For SSC model, RMSEP， AIC and modeling variables are decreased form 0.565, 1 047.20 and 535 to 0.541, 57.43 and 41, and Rv is increased from 0.920 to 0.930.
		2013 Vol. 34 (1): 49-53 [Abstract] ( 1513 ) [HTML 1KB] [ PDF 1834KB] ( 2221 )

	54	RLV ascent trajectory optimization based on hybrid PSO method
		ZHANG Ding-Ni, LIU Yi
		To solve trajectory optimization problem of reusable launch vehicle(RLV), a hybrid HPSO algorithm was proposed. Combining improved particle swarm optimization algorithm with sequential quadratic programming, a new particle swarm arrangement scheme was adopted to introduce timevarying inertia factors for adjusting searching velocity, and to improve the update scheme for velocity and position. Flight dynamic equations, engine model, aerodynamic model and constraint conditions of ascend trajectory optimization problems were obtained. The optimization design steps including collocation discretization, improved multi-neighborhood PSO and HPSO hybrid algorithm were determined, and the minimum fuel consumption problem was optimized and analysed. The calculation results show that a global highprecision solution of RLV trajectory optimization can be obtained even without a proper initial guess. The proposed algorithm can solve the trajectory optimization problem with good correctness, effectiveness and robustness.
		2013 Vol. 34 (1): 54-59 [Abstract] ( 1545 ) [HTML 1KB] [ PDF 1737KB] ( 2213 )

	60	Recognition of speech emotion on small samples by over-complete dictionary learning and PCA dimension reduction
		MAO Qi-Rong, ZHAO Xiao-Lei, BAI Li-Juan, WANG Zhi-Feng, ZHAN Yong-Zhao
		To solve the problems of sparse representation recognition algorithm with a large number of samples to train overcomplete dictionary and high degree of feature redundancy, the recognition algorithm of speech emotion on small samples by overcomplete dictionary learning and PCA dimension reduction was proposed. The feature dimensions were reduced by PCA method, and the over-complete dictionary was trained to identify samples. The speech emotional feature sparse representation was given to determine the steps of the proposed algorithm. The proposed algorithm was compared with BP and SVM for the same feature dimensions. The effects of the feature sparse representing on speech emotion recognition rate, time efficiency and space efficiency were analyzed. The experimental results show that the recognition rate of the proposed algorithm is better than those of SVM and BP, and the sparse feature is easy to handle. Using sparse features, the average recognition rate is increased by nearly 15%， and the time efficiency is improved by nearly 50% with increased space efficiency of 33%.
		2013 Vol. 34 (1): 60-65 [Abstract] ( 2207 ) [HTML 1KB] [ PDF 1468KB] ( 3119 )

	66	Rotor eddy current loss analysis of permanent magnet rotor based on double Fourier transforms
		ZHANG Tao, ZHU Huang-Qiu, SUN Xiao-Dong, YANG Ze-Bin
		To optimize the permanent magnet rotor structure and reduce the rotor eddy current loss, the rotor eddy current loss generated by slot effect of air-gap magnetic field in surface-mounted high-speed permanent magnet synchronous motor was analyzed. The magnetization models of permanent magnets were investigated to establish the eddy current loss mathematic models of permanent rotor. The air-gap magne-tic field data samples were extracted based on the air-gap magnetic field static analysis. For permanent magnets with parallel magnetization or Halbach magnetization, the air-gap magnetic field space, time harmonics and the corresponding eddy current loss caused by air-gap permeance variation were investigated by double Fourier transforms. The eddy current loss was calculated by transient finite element analysis at non-load state. The results show that the permanent magnet rotor with Halbach magnetization mode can effectively reduce the high order harmonics, and the rotor eddy-current loss is 34% of that with parallel magnetization.
		2013 Vol. 34 (1): 66-71 [Abstract] ( 1922 ) [HTML 1KB] [ PDF 2275KB] ( 2794 )

	72	Dynamic balance method without trial weight based on finite element model of dynamic balancer
		ZHOU Jin, WANG Yu-Long, GUO Qin-Tao
		To solve the poor efficiency of influence coefficient method in two-plane balancing for a rigid rotor caused by turning on and off many times, the dynamic balance method without trial weight of rigid rotor with soft bearing was investigated based on finite element model. The unbalance response test of dynamic balancer was conducted to obtain the initial unbalance signals of two rotor ends. The finite e-lement model of dynamic balancer was established by Nastran software. In the proposed model, two initial weights were added onto the two balancing planes to determine the unbalance signals. According to the two-plane balancing principle based on influence coefficient method for the rigid rotor, the influence coefficient of adding two initial weights on two testing points was calculated by Matlab to obtain rotor unba-lance. The results show that the balance weight of rigid rotor in dynamic balancer can be determined by the influence coefficient method combined with the finite element model, and the dynamic balance can be realized in one turning on.
		2013 Vol. 34 (1): 72-75 [Abstract] ( 2309 ) [HTML 1KB] [ PDF 2290KB] ( 3191 )

	76	Bandwidth blind estimation scheme of OFDM signals with low complexity at low SNR
		LIU Ming-Qian, LI Bing-Bing, WANG Jing-Shu, LI Yan-Ling
		To solve the problem of poor performance with large amount of calculation work for traditional orthogonal frequency division multiplexing(OFDM) bandwidth blind estimation scheme at low signal to noise ratio(SNR) over multipath channel, an OFDM bandwidth blind estimation strategy with low complexity was proposed. The Welch method was adopted to estimate the power spectrum of OFDM signals. The smooth spectrum was obtained by least square polynomial fitting. The derivation of smooth spectrum was calculated to extract the maximum and minimum positions. The statistical average value was considered as the final bandwidth blind estimation value by repeating many times. The steps of OFDM bandwidth blind estimation scheme were determined by theory analysis, and the simulation experiments were conducted under multi-path channel. The simulation results show that the correct rate of the bandwidth estimate scheme is 98.9% for SNR of 0 dB with multi-path channel. Compared with traditional method, the proposed method has better estimation performance with smaller calculation work at the conditions of low SNR and multi-path channel.
		2013 Vol. 34 (1): 76-80 [Abstract] ( 1601 ) [HTML 1KB] [ PDF 1510KB] ( 2602 )

	81	Seismic performance of frame wooden structure with energy dissipation joints
		ZHOU Ai-Ping, HUANG Dong-Sheng
		The wood beams and columns were connected into moment frame system with large lateral stiffness and ductility by the energy dissipation joints of Q235 steel. Compared to traditional Chinese wooden structures, the proposed structure has higher loading capacity because no mortise tenon connection is needed to joint columns and beams without weakened section of wooden members. Compared to the timber structures commonly used in North America, the buildings with the proposed structure are easier to be partitioned and are more economical without wooden shear wall to offer lateral stiffness. The structural analysis of a demo house with the system and the pseudo-static experiments for full scale joints were conducted. The results show that the joints have good capability to consume input energy by steel plastic deformation. The structure deflection can fulfill the requirements of the current code for seismic building design when the normal load combinations with frequency earthquake action were taken into account. Subjected to rare earthquake action, the plastic structure deformations are restricted in the joints with story drift less than 1/50 which is the criteria requirement of the code. The wooden frame with energy dissipation joints can meet the seismic fortification criterion of Chinese code.
		2013 Vol. 34 (1): 81-85 [Abstract] ( 1632 ) [HTML 1KB] [ PDF 1693KB] ( 2233 )

	86	Mechanism model test of interaction between bucket foundation and soil subjected to torsional resistance
		WU Ke, MA Ming-Yue, FAN Qing-Lai, CHEN Rong, HAO Dong-Xue
		Based on the model test, the failure mechanism of bucket foundation subjected to torsional resistance was investigated with different draw radio. The results show that the curves from model test are in good consistency with numerical calculations. The rotation angle of bucket foundation is increased by the increasing of torsional loading with almost linear relationship.At initial stage, the remarkable torsional loading variety leads to slight increase of rotation angle.When the imposed loading reaches a stable value,slight enhancement of torsional loading can result in marked variety of rotation angle with almost linear relationship. The inside and outside earth pressures of bucket foundation are axial symmetry. The inside earth pressure of foundation is increased from top to bottom with almost identical outside earth pressure. The annulus shear failure at the bottom of foundation is generated by torsional loading. The rotated shear deformation around the bucket foundation is generated with foundation axis as centre, and propagates around the foundation.
		2013 Vol. 34 (1): 86-90 [Abstract] ( 1478 ) [HTML 1KB] [ PDF 2285KB] ( 1725 )

	91	Fatigue damage of concrete slabs in wide box continuous composite bridge
		GAO Pu, WU Chong, SU Qing-Tian, SUN Yi-Ming, LIU Hai-Yan
		Based on the vehicle load model of fatigue design, the stress history of reinforcement in the concrete slab of northern approach of Jiubao Bridge with a multi-span continous composite bridge was obtained under vehicle load by finite element model. The stress spectrum of reinforcement was achieved by Rain-flow method according to the predicted traffic volume in the future of 100 years. Fatigue damage of reinforcement at different locations was achieved and compared to obtain the most disadvantageous place. The results show that fatigue failure of reinforcement may occur in deck slabs of steel-concrete composite bridges during service life, and the fatigue effect should be considered in the design. Reasonable lanes arrangement and small proportion of heavy truck are beneficial for fatigue performance of deck slabs.
		2013 Vol. 34 (1): 91-95 [Abstract] ( 1185 ) [HTML 1KB] [ PDF 2216KB] ( 2057 )

	96	Ultimate bearing capacity of circular footing with 6-DOF due to combined loading
		ZHANG Qi-Yi, ZHANG Ying, WANG Qi
		Based on the plastic limit equilibrium theory of soil, the ultimate bearing capacity of circular footing with 6 degrees of freedom(DOF) was analyzed by finite element analysis software of Abaqus. The results show that the vertical loading has remarkable effect on the shape and amplitude of the failure envelope of seabed under combined loading. The failure envelope of circular footing in three-dimensional loa-ding space is more round than that in two-dimensional loading space, and the slope of failure envelope has no sharp change.The horizontal loading and moment loading have strong impact on the shape and amplitude of failure envelope, while the torque loading has slight impact on the failure envelope in three-dimensional loading space. A critical formula was proposed to estimate the effect of loading components of combined loading on the failure envelope of seabed.
		2013 Vol. 34 (1): 96-100 [Abstract] ( 1303 ) [HTML 1KB] [ PDF 2237KB] ( 2049 )

	101	Effects of environmental conditions and stress level on chloride ion transport in concrete
		ZHANG Wei-Ping, ZHANG Qing-Zhang, GU Xiang-Lin, ZHONG Li-Juan, HUANG Qing-Hua
		To investigate the diffusion process of chloride ion in concrete under atmosphere environment, a series of tests were conducted under the conditions of different salt-fog spray angle, environment temperature, mass concentration of sodium chloride solution and compressive stress level. The results show that surface chloride ion mass fraction for specimens under different spray angles of salt-fog were different, which leads to a great change of diffusion degree of chloride ions in concrete. The surface chloride ion mass fraction is high when the angle of erosion surface is 0° or 45°, which causes severe erosion in concrete. The surface chloride ion mass fraction is increased with the increasing of mass concentration of sodium chloride solution until a stable value. The apparent diffusion coefficient of chloride ion is increased with the increasing of temperature, and decreased significantly with the increasing of compressive stress level due to the dense concrete by stress.
		2013 Vol. 34 (1): 101-106 [Abstract] ( 1405 ) [HTML 1KB] [ PDF 2107KB] ( 2248 )

	107	Micro structures and nano mechanical properties of beetle Sophrops elytra
		YANG Zhi-Xian, LIU Ze-Hua, DAI Zhen-Dong
		The micro structures of elytra were observed by scanning electron microscopy（SEM）， and the nano mechanical properties of elytra were determined and analyzed by nano indentation machine. The SEM images show that the elytra of Sophrops has empty laminate structure with dorsum, lumen and abdomen, which guarantees the light-weight characteristic of elytra with enough strength. On microscopic scale, the elytra shows non-smooth surface texture. The hardness and the modulus of elytra exocuticle by nano indentation tests are H of 0.48 GPa and Er of 8.81 GPa, respectively. The specific stiffness and the specific modulus are 600 MPa/(g·cm-3)-1 and 1.1×104 MPa?(g?cm-3)-1, respectively. The contact stiffness (K) of (2.28±0.16)×104 N?m-1 indicates excellent capability of deforming resis-tance. The nano mechanical properties of elytra are anisotropic with the maximum near sutual edge and the minimum at verge zone. The mechanical properties decrease gradually from cephalosome zone to empennage zone of elytra.
		2013 Vol. 34 (1): 107-111 [Abstract] ( 1855 ) [HTML 1KB] [ PDF 2966KB] ( 1926 )

	112	Electrodeposition of TiO2polyaniline nano composite films
		HAO Chen, BAI Yi, ZHANG Peng-Fei, XIE Wen-Jing, WANG Xiao-Hong
		To obtain uniform morphologies and crystal fine TiO2-polyaniline nano composite films, electrodeposition technology was used to prepare the composite films and to investigate the effects of deposition conditions. The optimum operation conditions with deposition potential of-1.5V(VS SCE), deposition pH of 1.5 ~ 2.0 and deposition time of 1 300 s were determined by the experiment. The samples were characterized by electrochemical method, scanning electron microscope and thermal analysis. The results show that the deposition film thickness increases with the decreasing of redox peak current. For different substrates, the composite film morphologies are significantly different.The SEM images reveal that aniline molecules in deposition solution have remarkable effect on the electrodeposition reaction, the size and the morphology of composite films. Adding small molecules of aniline in the solution is beneficial for the forming of fine crystal TiO2-polyaniline nanocomposite film.
		2013 Vol. 34 (1): 112-115 [Abstract] ( 1643 ) [HTML 1KB] [ PDF 1745KB] ( 3428 )

	116	Preparation and Ag-loading antibacterial activity of copper ferrite hollow fiber
		HUANG Da-Ming, XU Ming-Qiang, SHEN Xiang-Qian
		Copper ferrite(CuFe2O4) magnetic hollow fibers were prepared by organic gel-thermal decomposition method with nitrate and citrate acid as raw material. The structure, chemical composition, morphology as well as magnetic property of the precursor fibers and products derived from thermal decomposition of the precursor fibers at different temperature were determined by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. The results show that with the heat-treatment for 2 h at 800 ℃, nanofibers in hollow structure are successfully prepared with good ratio of length and diameter, and with average diameter of 1 μm. The saturation magnetization and residual magnetization are 42.5 and 23.0 A?m2?kg-1, respectively. Ag-loading CuFe2O4(Ag/CuFe2O4) nanofibers were fabricated with dip method. The antibacterial experiment shows that the Ag/CuFe2O4 fibers exhibit excellent antimicrobial activity against E. coli. The nanofiber content of 8 μg?mL-1 can completely inhibit 5×105 CFU ?mL-1 E. coli.
		2013 Vol. 34 (1): 116-120 [Abstract] ( 1282 ) [HTML 1KB] [ PDF 2568KB] ( 2011 )

	121	Hopf bifurcation analysis and amplitude control of modified Lorenz system
		WANG Xue-Di, ZHANG Wen-Li, CHEN Wen-Wen
		Hopf bifurcation analysis and amplitude control were corducted for a modified Lorenz system. An equilibrium point of Hopf bifurcation was searched. Based on the theory of bifurcation, a self-designed nonlinear controller was used to shrink the amplitude of the limit cycle caused by Hopf bifurcation. The correctness of theory analysis and the feasibility of amplitude control were verified by the numerical simulation.
		2013 Vol. 34 (1): 121-124 [Abstract] ( 1882 ) [HTML 1KB] [ PDF 1399KB] ( 2264 )

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