Loading...

Archive

    15 June 2005, Volume 26 Issue 6 Previous Issue    Next Issue

    OriginalPaper
    For Selected: Toggle Thumbnails
    OriginalPaper
    Variable structure control based on sliding model for a class of underactuated mechanical system
    Zheng, Yan (1); Zhu, Yuan (2); Jing, Yuan-Wei (1)
    2005, 26 (6):  511-514.  DOI: -
    Abstract ( 229 )   HTML   PDF (290KB) ( 818 )  
    Presents the design of variable structure control law on sliding mode for Acrobots as a class of underactuated mechanical system, with a modified exponential approximation law employed in the design. The simulation results showed that an Acrobot system remains stable if the variable structure controller designed in terms of linear model is employed in nonlinear system. Comparing with the control by pole placement method, a bigger stability range (or basin of attraction) and stronger robustness can be provided for an Acrobot system by the balance controller which is designed by variable structure control based on sliding model. The modified exponential approximation law can not only reduce effectively the tremble caused by variable structure control but make the Acrobot system come to a stable equilibrium state quickly.
    References | Related Articles | Metrics
    Algebraic stability criterion for T-S fuzzy systems
    Yang, Chun-Yu (1); Zhang, Qing-Ling (1); Zhou, Lin-Na (1)
    2005, 26 (6):  515-518.  DOI: -
    Abstract ( 218 )   HTML   PDF (1452KB) ( 678 )  
    Introducing a special matrix measure and based on the elementary properties of M-matrices, the stability of T-S fuzzy systems is analyzed, and shows that the stability of a judgement matrix constructed by the coefficient matrices of related subsystems implies the global stability of the T-S fuzzy systems. This algebraic stability criterion is different from the existing results which are usually obtained within the framework of Lyapunov stability. Then, according to PDC arithmetic, a controller design method with fuzzy state feedback is given using the algebraic criterion as well as a necessary condition given to the stability of the closed-loop T-S fuzzy system's judgment matrix. An example is presented to demonstrate the method.
    References | Related Articles | Metrics
    Multi neural network method for soft sensing and its application
    Chang, Yu-Qing (1); Wang, Xiao-Gang (2); Wang, Fu-Li (2)
    2005, 26 (6):  519-522.  DOI: -
    Abstract ( 238 )   HTML   PDF (973KB) ( 741 )  
    A Multi Neural Network method is proposed for soft sensing in a complex non-linear biochemical process. Low dimensional sample data are achieved by way of original data compression through principal component analysis, and a kind of modified sorting indices are used for these data to accomplish data hierarchy of the biochemical process model. Then, a soft sensing model is developed using multi neural network to fit the different hierarchical property of the process. The method has been applied to a glutamic acid fermentation process, and the testing results showed its effectiveness.
    References | Related Articles | Metrics
    Intelligent simulation model of molten iron transport system
    Long, De (1); Yao, Jian-Shi (2); Xu, Xin-He (3)
    2005, 26 (6):  523-526.  DOI: -
    Abstract ( 268 )   HTML   PDF (169KB) ( 718 )  
    Modeling and simulation of molten iron transport system are studied to develop a tri-layer intelligent simulation model. Based on OOCPN, a model of state evolvement is also developed available to the working position at the bottom layer, and the layer of scheduling is driven by the layer of simulation process control. The message transfer mechanism communicates well with the relation between state transition and simulation strategy efficiently. The intelligent decision-making behavior of dispatcher and engine driver in actual system is simulated efficiently by the expert systems for scheduling and collision avoiding decisions, which are both designed conceptually using hierarchical and carefully checked scheduling schemes. The results show that the intelligent simulation model developed provides a practical solution for the modeling and simulation of a transport scheduling system.
    References | Related Articles | Metrics
    Approach to wavelet-based image enhancement algorithm
    Zeng, Peng-Xin (1); Yao, Jian-Shi (2); Chen, Peng (1); Xu, Xin-He (1)
    2005, 26 (6):  527-530.  DOI: -
    Abstract ( 442 )   HTML   PDF (279KB) ( 1709 )  
    A wavelet-based algorithm is proposed for image contrast enhancement, which distinguishes the HF coefficients due to signal from those due to noise with the correlation between wavelet planes, then, increases wavelet coefficients due to signal and suppresses those due to noise. The algorithm solves the problem that some conventional enhancement methods enhance noise visibility at the same time enhance signal visibility. Experience results show that the algorithm can achieve an excellent balance between the enhancement of subtle image detail and the avoidance of noise amplification, and enhance often weak signal features against a background of relatively high noise.
    References | Related Articles | Metrics
    Swing up control based on sensory-motor schema for planar inverted pendulum
    Yao, Jian-Shi (1); Long, De (2); Xu, Xin-He (2)
    2005, 26 (6):  531-534.  DOI: -
    Abstract ( 262 )   HTML   PDF (164KB) ( 685 )  
    To realize the non-linear control over the swing-up of a planar inverted pendulum, a human-simulated intelligent control strategy based on sensory-motor schema is presented. Through the on-line characteristic identification memory, multi-mode control combining open-loop with closed-loop control and the intuitive logical reasoning mechanism, the strategy enables the pendulum to swing from its stable equilibrium point up to an unstable equilibrium point where it remains stabilized. The simulation results successfully proved that the intelligent controller integrating qualitative reasoning with quantitative control is able to achieve the swing-up control of the complicated, non-linear, strong coupling and naturally unstable planar inverted pendulum. Meanwhile, it also provides an effective solution to controlling of other nonlinear multivariable systems.
    References | Related Articles | Metrics
    Optimizing common sub-queries in XML data for regular path expressions
    Han, Dong-Hong (1); Wang, Guo-Ren (1); Qiao, Bai-You (1)
    2005, 26 (6):  535-537.  DOI: -
    Abstract ( 219 )   HTML   PDF (139KB) ( 579 )  
    Focusing on the query algorithm of XML data for path expressions and based on the marked suffix tree (MST), an optimizing algorithm is proposed for the common sub-queries in XML data for regular path expressions to improve the querying efficiency of path expressions through the redundancy eliminating technique. After a test done on the benchmark REOA, a performance analysis is made to the optimizing algorithm for the common sub-queries on MST basis. The result shows that the redundancy eliminating technique based on MST and used in XML data for path expressions will greatly improve the querying efficiency.
    References | Related Articles | Metrics
    Study on techniques of clustering XML data
    Qiao, Bai-You (1); Wang, Guo-Ren (1); Han, Dong-Hong (1); Zhao, Xiang-Guo (1)
    2005, 26 (6):  538-541.  DOI: -
    Abstract ( 211 )   HTML   PDF (163KB) ( 692 )  
    Analyzing the characteristics of data access in DOM standards, two methods are proposed for clustering XML data, which are based on the parent-child and sibling relationship separately. Then the probabilities of I/O occurrence of the two clustering methods are analyzed with respect to two typical operations of traversing over a tree, and two corresponding path expression algorithms to traverse over DOM tree are given, namely depth-first and breadth-first algorithms. A performance evaluation based on XMark and XMach is carried out as testing references.
    References | Related Articles | Metrics
    Research and design of a scheme to build an active node on internet
    Xue, Jian-Sheng (1); Wang, Guang-Xing (1)
    2005, 26 (6):  542-545.  DOI: -
    Abstract ( 131 )   HTML   PDF (155KB) ( 558 )  
    A scheme is proposed to solve the problem that the active data package can not be transferred on Internet by way of extending IP options to make IP protocol compatible with ANEP protocol. A storage link list and forwarding algorithm are designed on active node to enable the active data packages to be compatible with conventional IP data packages. A simulative testing was carried out for the transmission efficiency of both active and passive nodes, and the results showed that the mean difference between the two efficiencies affects not much the total time required for transmission. The feasibility of integrating active networks with Internet is also verified by modeling the setting process of the active node.
    References | Related Articles | Metrics
    Wavelet analysis of evoked electroencephalogram (EEG) in brain-computer interface
    Wang, Zhi-Yu (1); Wang, Hong (2); Li, Yi-Na (1); Wang, Xu (1)
    2005, 26 (6):  546-549.  DOI: -
    Abstract ( 300 )   HTML   PDF (1080KB) ( 742 )  
    To pick up the specific EEG signals from the strong background noise is the key function of brain-computer interface (BCI) system. Based on the characteristics of the specific thinking-evoked EEG signals (TES), an approach is proposed to determine their distribution and pick up their waveform from strong noise. The EEG signals are decomposed by the way of discrete wavelet transform. Then, an analysis is made by combining the wavelet singularity detection with wavelet statistic analysis to determine in which dimension of wavelet transform the specific thinking-evoked signals are located. Thus, the specific thinking-evoked EEG signals can be reconstructed without noise. This approach provides an effective approach to eliminate the noise embedded in EEG signals, which is especially suitable to pick up the specific evoked EEG signals.
    References | Related Articles | Metrics
    Silver preparation through ultrafine Ag particles displaced by Zn in silver nitrate solution with pulsed laser radiation
    Chen, Sui-Yuan (1); Ma, Li-Xia (1); Liu, Chang-Sheng (1); Cai, Qing-Kui (2)
    2005, 26 (6):  550-553.  DOI: -
    Abstract ( 274 )   HTML   PDF (200KB) ( 800 )  
    The effect of pulsed laser radiation on the preparation of silver was experimentally studied, of which the ultrafine Ag particles in AgNO3 solution were displaced by Zn powder, with the preparation mechanism analyzed. The laser beam energy was proved to be able to break up the clad particles which the larger Zn particles were wrapped up by Ag, thus expediting the displacement reaction. At the same time, the pulsed laser energy as a heat source will spur AgNO3 to decompose photothermically to precipitate ultrafine Ag particles. In this way the rate of precipitation of Ag rises. The Ag particles precipitated with and without pulsed laser radiation were compared with each other and analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results revealed that both the morphology and size of the two ultrafine Ag particles are different, and those with laser radiation are better than those without laser radiation in either grain size or purity.
    References | Related Articles | Metrics
    Tensile properties of SiC nanoparticle reinforced pure aluminum matrix composites
    He, Chun-Lin (1); Liu, Chang-Sheng (1); Sun, Xu-Dong (1); Cai, Qing-Kui (2)
    2005, 26 (6):  554-557.  DOI: -
    Abstract ( 268 )   HTML   PDF (201KB) ( 948 )  
    The SiC nanoparticle reinforced pure aluminum metal matrix composites (Al MMCs) were prepared through a powder metallurgy technique. Their microstructures and tensile properties were investigated. The results showed that SiC nanoparticles enhance the strength of pure aluminum significantly even if their content is very low, with the nanoparticles uniformly dispersed in the Al matrix. However, when the content becomes higher, the SiC nanoparticles are easily agglomerated to lower their strength enhancement effect on aluminum. The tensile fracture showed that the damage mechanism of the Al MMCs changes with the changing content of SiC nanoparticles.
    References | Related Articles | Metrics
    Phase precipitation of a new kind of Ni-base superalloy
    Cui, Tong (1); Liu, Shuang (1); Wang, Lei (1); Yang, Hong-Cai (1)
    2005, 26 (6):  558-561.  DOI: -
    Abstract ( 236 )   HTML   PDF (209KB) ( 1121 )  
    GH4199 alloy is a newly developed Ni-base superalloy which is precipitation hardened by an Ni3(Al, Ti) γ' phase with orderly fcc structure. The γ' phase precipitates coherently in nickel-rich fcc γ matrix. The phase precipitation behaviour in GH4199 was studied by means of phase analysis technology and TEM observation, as well as the calculation of electron vacancy number. Experimental results showed that almost a maximum amount of γ' precipitates can be found at 700-800°C and it begins to dissolve at above 800°C. Furthermore, the harmful brittle TCP phase can be found in this alloy at the temperature range of 700°C to 950°C after long-term aging. The electron vacancy number in GH4199 is 2.31-2.35, which is higher than that of critical number of μ phase formation, as shown in reference. Therefore, μ phase can be precipitated under thermo-exposure conditions. In contrast, the σ phase is also observed by TEM. The calculated electron vacancy number is less than the critical number (2.52) of σ phase formation as given by reference. The enrichment of Cr and Mo in γ-matrix after a large amount of γ' phase precipitation leads the σ phase to form in GH4199.
    References | Related Articles | Metrics
    Determination of phase equilibrium composition on Al-Zn side of Al-Zn-Cu ternary system
    Ren, Yu-Ping (1); Li, Hong-Xiao (1); Liu, Yu-Xiang (1); Hao, Shi-Ming (1)
    2005, 26 (6):  562-565.  DOI: -
    Abstract ( 224 )   HTML   PDF (211KB) ( 906 )  
    The phase equilibria and compositions of three solid solutions in the low Cu region of a Al-Zn-Cu ternary system were investigated by means of diffusion couple-EPMA technique. It was found that Zn contents in α1 and α2 both decrease due to Cu additions when α12 and α2/β are both in equilibrium at 320°C; Zn content in α increases with the small amount of Cu when α/β is in equilibrium at 260°C. The distribution ratios of Cu are all unsymmetrical when α12, α2/β and α/β are all in equilibrium, i.e., Cu content in the latter phase is much more than that in the former one. This means that the α112 phase boundary approaches to Al-rich corner due to Cu additions at 320°C, and the α/α+β phase boundary is along the increasing direction of Zn content due to Cu additions at 260°C.
    References | Related Articles | Metrics
    Effect of austenite recrystallization on microstructure and properties of Q345 plate steel
    Zhu, Fu-Xian (1); Liu, Yan-Chun (1); Li, Yan-Mei (1); Wang, Guo-Dong (1)
    2005, 26 (6):  566-569.  DOI: -
    Abstract ( 689 )   HTML   PDF (413KB) ( 1752 )  
    The recrystallization behavior and accumulative effect of strain of Q345 plate steel were investigated by thermal simulating tests and pilot rolling tests. How the recrystallization affects the microstructure and properties was discussed, thus determining the way to control the pass reduction/deformation in austenite recrystallization region and partial recrystallization region on principle. It was found that increasing the temperature-holding thickness of billet at 880-820°C as the temperature range of finish rolling is favorable to grain refining. The findings have been applied in the 3500 mm Plate Mill Shougang where the average grain size of the plate rolled is up to ASTM Grade 10-12 with the band structure down to below Grade 1.5.
    References | Related Articles | Metrics
    Electrochemical behavior of lithium carbonate in KCl-LiCl melt
    Zhang, Ming-Jie (1); Li, Ji-Dong (1); Wang, Yao-Wu (1)
    2005, 26 (6):  570-573.  DOI: -
    Abstract ( 253 )   HTML   PDF (158KB) ( 844 )  
    The electrochemical behavior of Li2CO3 in KCl-LiCl melt was investigated by continuous pulse-oscillograph and potential sweep. It was found that there is a peak of oxidation current ahead of the potential at which the negative chlorine ions precipitate and the current peak is caused by the CO2 which is produced by the O2- ionic discharge due to Li2CO3 addition. In the KCl-LiCl system the back EMF increases with increasing current density, but the back EMF will decrease greatly at the same current density if adding Li2CO3. Using Li2CO3 instead of LiCl as the raws material in metallic lithium production by galvanolysis is regarded as the new trend of lithium galvanolysis because Li2CO3 will not only minimize the environmental pollution but also reduce the cost.
    References | Related Articles | Metrics
    Effect of additives on microstructure and properties of inert anode of NiFe2O4 spinel
    Xi, Jin-Hui (1); Yao, Guang-Chun (1); Liu, Yi-Han (1)
    2005, 26 (6):  574-577.  DOI: -
    Abstract ( 218 )   HTML   PDF (184KB) ( 721 )  
    In order to improve the properties of resistances to thermal shock and bending of inert anode of NiFe2O4 spinel, such additives as MnO2, TiO2 and V2O5 in trace amount were added to its raw materials and then they were all sintered together at 1200°C for 6 hr, i.e., preparing a doped inert anode by the process of powder metallurgy. The effects of different kinds and amounts of additives on sintering and microstructure of the inert anode were studied, as well as the effect of microstructure and density on its properties, such as the resistances to thermal shock and bending. The results showed that the three additives can benefit the sintering process to different degrees and improve the density. The additive MnO2 can make grains finer with grain size distributing more uniformly. But TiO2 or V2O5 will make the grains coarser with non-uniform grain size distribution. It means that only MnO2 can improve the resistances to thermal shock and bending.
    References | Related Articles | Metrics
    Generating mechanism of surface morphology finished by abrasive jet with grinding wheel as restraint
    Li, Chang-He (1); Cai, Guang-Qi (1); Li, Qi (1); Liu, Feng (1)
    2005, 26 (6):  578-581.  DOI: -
    Abstract ( 260 )   HTML   PDF (203KB) ( 1306 )  
    A novel abrasive jet finishing process with grinding wheel as restraint is proposed to solve the actual problem that after grinding process the surface layer defects were often found on workpiece and, therefore, important parts were thus required to finish or polish again after grinding so as to remove the surface layer defects and diminish roughness and rippled grinding cracks. Integrating grinding process and abrasive jet process into one features the process proposed. Discussing some existing surface finishing processes, the generating mechanism of surface morphology finished by the novel process was investigated. In such a process the energized free abrasive in wedge-like zone which polish, wipe off, cut off even plough shallowly the workpiece surface material, are the core factor in material removal. On the other hand, the lateral extrusion of abrasive fluid is the main factor of homogenizing and lowering ripples. Testing results showed that the process is efficient to remove the plastic deformation due to overmachining, reduce surface roughness and homogenize ripples. It is theoretically important and practical to precision finishing process in metal working.
    References | Related Articles | Metrics
    Effect of boron-doping on morphology and microstructure of carbon nanotube
    Wang, Zhi (1); Ba, De-Chun (1); Cao, Pei-Jiang (2); Liang, Ji (3)
    2005, 26 (6):  582-584.  DOI: -
    Abstract ( 260 )   HTML   PDF (170KB) ( 1027 )  
    Boron-doped carbon nanotubes (CNTs) were prepared on porous silicon substrate by electron cyclotron resonance-chemical vapor deposition (ECR-CVD), with CH4, B2H6 and H2 used as source gases and Fe3O4 nanoparticle as catalyst. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS) were used to characterize the morphology, microstructure and composition of specimens. Comparing with the undoped CNTs, the boron-doped ones show the change in not only the morphology of CNT films, i.e., from high-orientability and intensive to low-orientability and scattered arrangement, but in the microstructure of CNTs, i.e., from hollow to bamboo-like tubes with bigger outer diameters, thicker tube wall and rough surface. Thus, the growth rate of boron-doped CNTs is lower than that of undoped CNTs.
    References | Related Articles | Metrics
    Preparation of ZnO nanoparticles using zinc oxalate dihydrate as precursor
    Yin, Wan-Zhong (1); Ding, Ya-Zhuo (1); Han, Yue-Xin (1); Yuan, Zhi-Tao (1)
    2005, 26 (6):  585-587.  DOI: -
    Abstract ( 255 )   HTML   PDF (691KB) ( 955 )  
    Sphere-like and cubic ZnO nanoparticles were synthesized using ZnCl2 and oxammite as raw materials by way of the precipitation reaction through which the precursor ZnC2O4 · 2H2O was obtained and then pyrolyzed. TEM and XRD results showed that they are of crystalline zincite with grain size 25-80 nm. The TG-DTA test was carried out for the precursor. It was revealed that increasing the reaction time and pyrolysis time/temperature will increase the size of primary particles. On the other hand, increasing reaction temperature (below 90°C) will take opposite effect. When the original concentration of Zn2+ is below 0.5 mol/L the size of the particles change little (25 nm), but when it reaches 0.7 mol/L the size ascends to 80 nm.
    References | Related Articles | Metrics
    Shock absorption model of composite foundation and calculating example
    Wang, Feng-Chi (1); Zhu, Fu-Sheng (1); Yang, Xu (3); Bai, Quan (1)
    2005, 26 (6):  588-590.  DOI: -
    Abstract ( 268 )   HTML   PDF (269KB) ( 819 )  
    The shock absorption capacity of composite foundation plays mainly the roles of amplitude reduction, viscous damping for energy consumption and friction energy consumption. Based on the composite foundation's shock absorption mechanism, the foundation and cushion can be simplified to be a vibrating system involving mass, damping and elasticity with multiple degrees of freedom, of which the frictional action is also taken into account. Then, a shock absorption model and dynamic equation are developed, with a program given using wilson-θ method to compute the equation. A calculating example shows that the maximum interbedded displacement due to composite foundation and cushion is much less than that due to pile foundation. In addition, the maximum value of sliding response spectrum also decreases. All these reveals that the effect of shock absorption is obvious.
    References | Related Articles | Metrics
    Research on measurement of bankrupt risks
    Zhuang, Xin-Tian (1); Jiang, Rui-Chun (1); Zhuang, Xin-Lu (2)
    2005, 26 (6):  591-594.  DOI: -
    Abstract ( 672 )   HTML   PDF (260KB) ( 1306 )  
    The factors that determine the bankrupt risk can be represented both qualitatively and quantitatively. To effectively recognize, measure and control bankrupt risk, an approach is suggested combining qualitative recognition with quantitative calculation based on modeling. A method based on parameter distribution and fuzzy recognition is adopted to classify bankrupt risk. In addition, a probability inference for bankrupt, a probability model to measure bankrupt risk and a probability distribution function of businesses lifetime are given. Focusing on business assets and based on the pricing theory of financial options, the model of bankrupt probability is developed. Finally, a planning model to control bankrupt risk is given.
    References | Related Articles | Metrics
    Consistency analysis of expert group's judgement based on reciprocal judgement matrices
    Chen, Xia (1); Fan, Zhi-Ping (1)
    2005, 26 (6):  595-598.  DOI: -
    Abstract ( 231 )   HTML   PDF (161KB) ( 676 )  
    With respect to the consistency problem of expert group's judgement based on the reciprocal judgement matrix in terms of preferential information form, an analytic method is proposed. Introducing some definitions and characteristics of reciprocal judgement matrix, the consistency index of expert group's judgement and that of each expert's judgement are given. Then, the way to recognize the expert group's consistency, and adjust the inconsistency among the group because of different preference is expounded. According the consistency index of each expert's judgement, the level of an expert's judgement can be recognized. A numerical example is given to illustrate the use of the analytic method proposed.
    References | Related Articles | Metrics
    Predicting large amount of accrued payables to redeem open-end funds on Bayes theory basis
    Li, Xia (1); Wang, Jin-Yu (2); Cheng, Wei (3); Pan, De-Hui (1)
    2005, 26 (6):  599-602.  DOI: -
    Abstract ( 253 )   HTML   PDF (163KB) ( 452 )  
    The concepts of large amounts of redemption (LAR) and Bayes large amounts of redemption (BLAR) for open-end funds are suggested. The formula to calculate LAR is obtained on the basis of the theory of compound Poisson distribution and limitation. Because the parameters of redemption amounts distribution are uninterruptedly changing in case of open-end funds, it is more appropriate to predict the large amounts of redemption by using Bayes method. The formula to calculate BLAR is thus derived in normal distribution. In conclusion, a new reasonable way to keep away from the liquidity risk is provided to the fund management.
    References | Related Articles | Metrics
    Eigenvalue estimation and preconditioning for BTA-1B
    Li, Zheng (1); Shao, Xin-Hui (2); Li, Chang-Jun (2)
    2005, 26 (6):  603-605.  DOI: -
    Abstract ( 274 )   HTML   PDF (130KB) ( 790 )  
    The estimation for the bounds of the eigenvalues of matrix BTA-1B is studied on the assumption that the matrix A is symmetric and positive definite (SPD) and B has full column rank. Furthermore, the estimation for the spectral condition number of BTA-1B is obtained. Based on what was concluded above, it is proved that Q=BTB is a good preconditioner for matrix BTA -1B provided A is well conditioned. In the numerical experiment, the Stokes equation is solved by preconditioned conjugate gradient method (PCG). The experimental result demonstrates that Q=BTB is indeed an effective preconditioner. This result is consistent to the numerical results of some references.
    References | Related Articles | Metrics
    Magnetization behavior of two-dimensional diluted Ising ferromagnet
    Wei, Guo-Zhu (1); Gu, Yong-Wei (1); Xin, Zi-Hua (1); Zhang, Qi (1)
    2005, 26 (6):  606-608.  DOI: -
    Abstract ( 243 )   HTML   PDF (164KB) ( 1047 )  
    The magnetization behavior of pure spin (1/2) diluted Ising model with square lattice in the outer magnetic field was investigated. Using the effective-field theory with correlation, the magnetization and susceptibility formulation of the model were derived theoretically. How the main physical quantities change with temperature and doping concentration in the process of magnetization were discussed. Under the conditions that the doping concentration and temperature remain unchanged, the magnetization increases with the outer magnetic field intensity; if the doping concentration and magnetic field are of given values, the magnetization will decrease with the temperature becoming higher. The relationship between order parameters and doping concentration of the system was obtained in the ground state, as well as the relevant phase diagram.
    References | Related Articles | Metrics
    Magnon softening in two-dimensional insulating ferromagnet under zero absolute temperature
    Cheng, Tai-Min (1); Xianyu, Ze (1); Du, An (1)
    2005, 26 (6):  609-612.  DOI: -
    Abstract ( 162 )   HTML   PDF (192KB) ( 571 )  
    A magnon-phonon interaction model is developed in two-dimensional insulating ferromagnet of which the magnon spectrum is studied in accordance to Matsubara-Green function. The magnon dispersion curve is calculated on the main symmetric points lines in Brillouin zone for different parameters in the system. It is found that at the boundary of the zone the magnon linewidth broadens and magnon softens both most obviously. The influences of longitudinal phonon and transverse phonon on magnon softening and magnon linewidth broadening are compared, and the influences of different parameters on them are also illustrated.
    References | Related Articles | Metrics