最新刊期
      卷 38 ， 期 4 ， 2006
      • Vol. 38, Issue 4, Pages: 1-4(2006)
        摘要：Abstract:Existing researches on coal bed methane is based on Darcy's law. But experiments show that gas flow in low permeability porous media is nonlinear. Methods of experiment, theory and calculation were used to establish a new nonlinear flow law. Experiment results of gas flow in low permeability pore fissure media were analyzed. Universal characteristics of the flow were generalized. The relationship between flow velocity and pressure gradient is a continuous curve which changes from a hollow curve under a low pressure gradient to a line under a high pressure gradient. The line is extended but does not stretches to the origin so that a starting pressure gradient appears. A new law of nonlinear flow was established according to the characteristics. Dimension and physical meaning of parameters of the new law are clear. Results indicate that there is a good agreement between the new law and the experiment of gas flow in low permeability pore fissure media. Darcy's law is just a special case of the new law. The new law can be used in theoretical and practical research on the gas flow in low permeability pore-fissure media. It lays the foundations of researches on mechanisms of coal-bed gas flow and provides development of coal bed gas resources with new basis.  
        关键词：Low permeability;pore-fissure media;nonlinear flow   
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      • Vol. 38, Issue 4, Pages: 5-9(2006)
        摘要：Abstract:Using ANSYS software, this paper conducted numerical simulation and optimization on key constructional techniques, such as the height of excavated bare surface at the mouth of surge tank, advanced consolidation grouting of surrounding rock, grouting hole anchor line forecast fasten technical, lock collar beam fasten at the pit bank, the support pattern of pneumatically placed concrete and anchor prop, whole overhang concrete lining and steel lining and so on for Futang surge tank in Minjiang river, Sichuan province. The paper also makes numerical emulation of the whole progress and monitoring feedback analysis. This has not only guided the safe construction of the project but also has provided good references to other projects alike.  
        关键词：complex geological condition;surge tank;construction modeling   
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      • Vol. 38, Issue 4, Pages: 10-14(2006)
        摘要：Abstract:The physical mechanism of soil water transportation is explained using fractional Brownian motion(FBM).Quantitative mathematical physical analysis model is proposed. The analytical solution demonstrates fractal characteristics of Lévy distribution. Practical example is used to verify the abnormal transportation of soil water. The research has shown the intrinsic mechanism of soil water movement and the result is feasible.  
        关键词：FBM;soil water;physical mechanism;Lévy distribution;abnormality transportation   
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      • Vol. 38, Issue 4, Pages: 15-18(2006)
        摘要：Abstract:Due to the inconsistency of dimensionless pollutant transverse diffusion coefficients in a physical model and its corresponding prototype river, the similarity law for the distorted physical model on water pollutant diffusion was investigated. It was found that the transform relationship of dimensionless transverse diffusion coefficients between the distorted model and the prototype river was related with the distortion scale ratio, αyp=αym·λl/λh， i.e. proportional to the horizontal scale and inverse proportional to the river scale. Validated by the experimental data between a prototype and a model, the result can provide guidelines for lab experiment in the research of transverse mixing of pollutant.  
        关键词：distorted model;pollutant;transverse mixing;distortion scale ratio;similarity   
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      • Vol. 38, Issue 4, Pages: 19-23(2006)
        摘要：Abstract:Simplified temperature calculation methods of steel roof members of large-space structures under fire conditions have not been studied systematically. Several simplified formulae or calculation methods for small compartment fires have been applied to a large-space structural model with typical dimensions, and comparisons were made between simplified calculation and numerical simulation results. Accuracy of these methods and synthetic appraisals are given relied on theoretical analysis, and some suggestions of amendment are proposed.  
          
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      • Vol. 38, Issue 4, Pages: 24-28(2006)
        摘要：Abstract:In the nonlinear computation of the spiral case structure of Three Gorge Power Station, damage mechanics is introduced to study the concrete cracks from microcosmic to macrocosmic scope. This can put forward significant reference to structural reinforcement design and damage detection. In this paper, with the new three dimensional orthogonal damage finite element program, the damage distribution, stress and strain of the spiral case structure are fully analyzed in the conditions of different internal pressures. According to the result, it can be concluded that the structure has high safety stock and its design is rational.  
        关键词：spiral case structure;damage analysis;concrete;crack   
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      • Vol. 38, Issue 4, Pages: 29-33(2006)
        摘要：Abstract:Taken low head power station such as Jinzitan、Chuanwanggong and Leying as study objects,this paper studied the altitude、form、arrangement manner of the approach wall and sediment storage wall in front of the water intake through experiments.The operation mode of hydraulic power station and sand sliting situation in front of the water release and sand sluicing gate are also studied.The results showed: As long as taking reasonable measures, we can guarantee the water inlet of convex bank fetch top layer clear water to ensure hydraulic power station work in good condition. Years of practice has verified the research conclusions.  
        关键词：low head;hydraulic power station;convex bank;water intake and sediment control   
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      • Vol. 38, Issue 4, Pages: 34-38(2006)
        摘要：Abstract:The research of finding optimal observation place for inversing concrete gravity dam parameters was studied firstly through analytical sensitivity analysis theory, the conclusion indicated that the displacement of dam crest is the most suitable data for inversing dam parameters. Then a novel stochastic search optimization algorithm—Artificial Fish Swarm Algorithm (AFSA ) was presented, according to the incremental displacement of dam crest, it was applied to inverse the parameters of gravity dam and bedrock,at the meantime, the numerical stability of AFSA was also analyzed. Results of computational example show that the proposed inverse method can rapidly converge to the global optimum solution, and has the characteristics of global convergence and the strong ability of noise resistance. So it can be concluded that the inverse method of dam parameters based on AFSA is workable and reliable.  
        关键词：parameter inversion;sensitivity analysis;artificial fish swarm algorithm;numerical stability;dam   
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      • Vol. 38, Issue 4, Pages: 39-43(2006)
        摘要：Abstract:In order to analyze the influences of different stiffeners on joint performances in extended end plate connections, the finite element method with large and elasto-plastic deformation, suited to contact problems, was used. Effects of the size of extended end-plates and backing plates for column flange on rotational stiffness and resistance of the beam to column connection are studied. Developments of end-plate deformation and departure from each other between end plate and column flange were studied. It is found that the equilateral triangular stiffener with the beam web thickness will yield and/or buckle prematurely. When the stiffener angle is 63.4°, it can increase arm length against bending of the connection, thus reducing bolt tensile force, delaying the local buckling of beam compressive flange and forcing the beam plastic hinge to the end of the stiffeners, therefore such stiffeners enhance strength and stiffness of the connection significantly.  
        关键词：beam-column connection;extended end plate connection;end plate stiffener;moment rotation curve   
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      • Vol. 38, Issue 4, Pages: 44-48(2006)
        摘要：Abstract:The cross-section curvature ductility ratio for R.C inequiaxial T-shaped , L-shaped and cross-shaped columns is calculated by numerical method．On the basis of calculation results, the influence of design parametrs(axial compression ratio,content of longitudinal reinforcement,content of stirrup,grade of concrete strength and grade of longitudinal reinforcement) on the cross section curvature ductility ratio is analyzed.The relationships between cross-section curvature ductility ratio versus the parameters are presented.It's helpful for the evaluation of aseismatic performance on R.C inequiaxial T-shaped ,L-shaped and cross-shaped columns.  
        关键词：nonlinear analysis;inequiaxial special-shaped columns;curvature ductility ratio   
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      • Vol. 38, Issue 4, Pages: 49-52(2006)
        摘要：Abstract:In order to study the size dependence of the fracture toughness, pure mode I and pure model Ⅱ fracture tests for polymethyl methacrylate (PMMA) were performed under quasi static loading by using central cracked circular disk specimen. The experimental results show that the fracture toughness of PMMA is dependent on the relative crack length α, and the pure model I fracture toughness and the pure model Ⅱ fracture toughness decrease with increasing the relative crack length α. The relative crack length has a larger effect on the pure model I fracture toughness, and a smaller effect on the pure model Ⅱ fracture toughness. In addition, the experimental results also show that the pure model Ⅱ fracture toughness of PMMA is less then the pure model I fracture toughness.  
        关键词：polymethyl methacrylate (PMMA);central cracked circular disk (CCCD);fracture toughness;size dependence   
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      • Vol. 38, Issue 4, Pages: 53-57(2006)
        摘要：Abstract:Faced with the problem of the loose and extrusion, and then the malfunction of the osseointegrated implant for percutaneous osseointegrated artificial lower limb attachment after long-time of use caused by stress shielding, which occurred always around traditional one part implant,a new type of implant—multi part implant was developed. Based on CT data and under the maximal load during a normal walking cycle, 3D finite element analysis was carried out to analyze the stress of bone around the new implant in three cases of distally truncated femur at high-position、middle-position and low-position. Results showed that stress shielding and stress concentration under the new type of implant are reduced effectively compared with the traditional one-part implant, and the stress distribution is much close to the natural bone. Application for distally truncated femur at middle-position and low-position was much better, while stress concentration was marked at high-position. Meanwhile, the stability in vivo can also be maintained with the multi part implant.The new implant can markedly reduce the adverse effect of stress shielding, which is promising applied for prosthetic limb.  
        关键词：multi-part osseointegrated implant;stress shielding;3D finite element analysis;percutaneous osseointegrated artificial limb   
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      • Vol. 38, Issue 4, Pages: 58-63(2006)
        摘要：Abstract:Based on the principles of thermodynamics and hydromechanics, an equation was deduced to predict the vertical position of the interface formed by an inertial gas gap, by which the static pressure transducer is protected from contacting with viscous and corrosive slurries inside a special tube for on-line measurement of the density and level of liquid surface for the flowing system. The interface fluctuation due to the change of temperature and pressure inside the measuring tube was calculated for water and air system within the range of 160 ℃ and 0.7 MPa. An analytic criterion for gas escape which eventually leads to invalidation of measurement was obtained. Furthermore a mass transfer model was proposed to analyze the negative effect of mass transfer of gas molecules through the interface to the flowing liquid, which may cause invalidation of measurement if the majority of gas loses from the measuring tube. It was demonstrated by the calculation that this process of mass transfer is very slow for the slightly dissolved gas liquid system. Taking air water as an trial system, the experiments were made to verify the model. Under a constant pressure of 0.2 MPa and the temperature of 50 ℃ and 80 ℃ respectively, the change of interface position inside the measuring tube due to mass transfer was less than 5% during a period of 90 days, well consistent with the model prediction. It was indicated that the method was fitted well with the engineering requirement for reliable application.  
        关键词：viscous slurry;gas gap;static pressure measurement;reliability analysis   
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      • Vol. 38, Issue 4, Pages: 64-68(2006)
        摘要：Abstract:Based on the definition of physical field entropy, a temperature field entropy analysis method was proposed. Depended on researches of driving force irreversible dissipation for heat transfer, temperature field entropy quantitatively expresses the irreversible loss of system in heat transfer process. According to the study of rectangular fin efficiency, a quantitative relationship was deduced that temperature field entropy is proportional with heat conduction coefficient and thickness or it is inverse proportional with length. Compared with the curve of fin efficiency, temperature field entropy can not only reflect system's thermodynamics capability but also find out the change mechanism of fin efficiency. It is valuable for the actual application to optimize thermal system design.  
        关键词：temperature field entropy;driving force dissipation for heat transfer;entropy generation analysis;fin efficiency   
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      • Vol. 38, Issue 4, Pages: 82-85(2006)
        摘要：Abstract:The PISA (Proximal Isovelocity Surface Area) method based on the foundation of the Doppler color proximal flow convergence, has been accepted by clinic to assess the severity of the central MR (mitral regurgitation). However, the result tend to be greatly underestimated when the PISA is applied to eccentric MR. In order to estimate eccentric MR，two parameters named turbulent intensity and regurgitate angle were proposed to modify the effective regurgitate orifice area (EROA) based on traditional PISA algorithm. 23 patients with various severity of eccentric MR were studied to compare modified PISA algorithm with the traditional one. The results showed the grading results of eccentric MR evaluated by the modified PISA algorithm were more rational and accurate, compared with the results obtained from live-3D color Doppler flow imaging method.  
        关键词：eccentric mitral regurgitation;proximal isovelocity surface area algorithm;effective regurgitant orifice area;turbulent intensity;regurgitate angle   
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      • Vol. 38, Issue 4, Pages: 86-91(2006)
        摘要：Abstract:A theoretical model for a humidifier of PEM fuel cell systems was developed and analyzed based on the theory of heat transfer and mass transfer, which is intended to be used for the investigation of the performance of a humidification system. A general calculation methodology was developed to implement this model. Knowing a set of gas feeding conditions (i.e., pressure, temperature, flow rate) and physical conditions of a humidifier (i.e., channel geometry, heat transfer coefficients, etc.), the model could provide information regarding the relative humidity and temperatures of outlet gases, as well as the temperature of outlet water. Using the parameters of 1 kW PEM fuel cell system, the proposed model was implemented in Simulink environment. The simulation results showed good agreement with the performance of the test bench.  
        关键词：humidification system;proton exchange membrane(PEM) fuel cell;relative humidity   
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      • Vol. 38, Issue 4, Pages: 96-100(2006)
        摘要：Abstract:Polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyacrylic acid (PAA) and methyl cellulose (MC) were used as dispersants, and the effects of dispersant dosage on the rheological behaviors and electromotive properties of hydroxyapatite (HA) slurry were studied. The results indicated that the slurry was the typical pseudoplastic fluid which could be described by shear thinning. The rheology, electromotivity and thixotropy of the slurry could be significantly improved when 0.5% MC was added to the HA slurry. The mechanism of the effect of different dispersants on the rheology of HA slurry was also explored. Finally, the HA slurry with improved rheological and thixotropical properties was prepared successfully. The porous HA ceramics with thin porous wall and uniform porous diameter were also fabricated by the slip casting process.  
        关键词：hydroxyapatite;rheology;slurry;slip casting   
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      • Vol. 38, Issue 4, Pages: 101-104(2006)
        摘要：Abstract:The sintering dynamics of Hydroxyapatite（HA）agglomerate powders which are synthesized by deposition method and then treated under the shock wave has been analyzed. The sintering characteristics and the sintering action energy of being shocked and unshocked HA are studied respectively according to the change of linear shrink rate during the course of sintering. The results of study show that the sintering action energy of being shocked and unshocked HA are estimated to be 63.2 kJ/mol and 106.5 kJ/mol respectively. The sintering characteristics of HA powders have been improved after treated by shock wave and the strength of HA ceramics made of the shocked sample can be obviously enhanced. The treatment with shock wave is an effective method to improve the sintering of HA agglomerate powders, which can widen the application field of HA in biomedical engineering.  
        关键词：hydroxyapatite;shock-activating;biomedical ceramics;sintering dynamics   
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      • Vol. 38, Issue 4, Pages: 105-109(2006)
        摘要：Abstract:In order to improve the toughness of Fe-B-C alloy, the effect of Rare earth(RE)-Ti-N composite modification on the microstructures and properties of Fe-B-C alloy was researched. The results showed that the solidification structures of Fe-B-C alloy is refined obviously and the distribution of structures is uniform after composite modification. Moreover, the compound containing boron and titanium appeared in Fe-B-C alloy containing RE-Ti-N. The compound containing boron and titanium was different from the network Fe2B in the common Fe-B-C alloy, whose distribution was broken network and lump. After heat treatment the boride in Fe-B-C alloy containing RE-Ti-N turned into nodular and rod and the toughness of Fe-B-C alloy is increased obviously, from 8～10 J/cm2 to 22～25 J/cm2. Fe-B-C alloy containing RE-Ti-N was used to produce the guide of rolling mill, its abrasion resistance is 1.3 times higher than that of high Ni-Cr alloy steel.  
        关键词：Fe-B-C alloy;boride;modification;impact toughness;guide piece   
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      • Vol. 38, Issue 4, Pages: 110-116(2006)
        摘要：Abstract:To protect the profit of DS (Data Supplier) and authorized users better and provide multiple services for users, a new multi service oriented collusion resistant asymmetric traitor tracing scheme was proposed,in which the session key S was divided into a sum of S1 and S2. Under the condition of large integer factoring problem, S1 was decrypted by constructing a special equation (scheme 1). Under the condition of discrete logarithm problem, S2 was decrypted by OPE (Oblivious Polynomial Evaluation) protocol and Lagrange Interpolation Polynomial (scheme 2).On the basis of the combination of the scheme 1 and scheme 2, a new traitor tracing scheme was formed.The new scheme has many advantages such as multi-service, collusion-resistance, asymmetry, black-box tracing, forward-security and backward security,and its whole capabilities is also better than existing ones.  
        关键词：multiple-service;collusion-resistance;asymmetric;black-box tracing;forward-security;backward-security   
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      • Vol. 38, Issue 4, Pages: 117-121(2006)
        摘要：Abstract:In order to improve the capability of the algorithm, based on the analysis of basic particle swarm optimization (PSO) and inspired by some ideas of simulated annealing (SA) and genetic algorithms (GA), a novel PSO with stochastic stagnation,SSPSO, was presented, in which a key parameter,acceptation probability, was introduced and the formula for flying velocity of the particle was changed, resulting in the particles stochastically stagnating in some directions. The simulations indicated that the presented algorithm can improve the search efficiency obviously while the stabilization was maintained if only the acceptation probability was selected properly. At last, a further analysis was made contrasting with traditional search algorithm SA and GA.  
        关键词：stochastic stagnation;particle swarm optimization;swarm intelligence;acceptation probability   
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      • Vol. 38, Issue 4, Pages: 122-125(2006)
        摘要：Abstract:In order to describe internet worm propagation, a novel subsection model of network worm propagation was put forward. The model divided Worm propagation into three subsections and modelled each one separately. The model was verified via the data of the worm propagation.Based on the parametes of the subsection model,strategies of controlling network worm were proposed.  
        关键词：network worm;propagation;modeling   
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      • Vol. 38, Issue 4, Pages: 126-130(2006)
        摘要：Abstract:In many applications of sonar systems, broadband beamformer design is one of the most important issues due to its capability of retaining target signatures in the mainbeam region and suppressing noise and interference from sidelobe region. In order to decrease the influences of amplitude and phase errors of the FIR filter for broadband beamforming, the FIR digital filter with rigid linear phase was obtained by linearly constrained minimum variance adaptation algorithm, and an iterative algorithm was used to design approximate equiripple FIR digital filters through adaptively obtaining optimum cost function based on amplitude error function. These improved approaches resulted in the best weights of the FIR filter to reach a best fit between the FIR digital filter response and the design requirements. Results of computer simulation for a 10 element equally spaced line array showed that these algorithms were effective, and can be applied to arbitrary array.  
        关键词：broadband beamforming;adaptive iterative algorithm;FIR filter;LCMV filter   
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      • Vol. 38, Issue 4, Pages: 131-135(2006)
        摘要：Abstract:To overcome the shortcoming that the effect of median filter for impulsive noise was influenced seriously by the window size and noises density, the detachment of the noise detection window and the noise removal window was proposed for corrupted images by pepper and salt noises. Some strategies, such as the large window for noise detection and the small window for noise removal, and the adaptive filter for impulsive noises removal, was employed to improve the performances of the filter. The experiment results showed that the filtering performances were meliorated by a long way. Meanwhile, the filtering performances of the filter were excellent for different noise densities.  
        关键词：impulsive noise;median filter;the double windows for filtering;noise detection   
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      • Vol. 38, Issue 4, Pages: 136-140(2006)
        摘要：Abstract:The ideas of adaptive nonlinear damping and changing supply functions were used to counteract the effects of parameter and nonlinear uncertainties, unmodeled dynamics and unknown bounded disturbances. The high-gain observer was used to estimate the state of the system. A robust adaptive output feedback control scheme was proposed for nonlinearly parameterized systems represented by input output models. The scheme does not need to estimate the unknown parameters nor to add a dynamical signal to dominate the effects of unmodeled dynamics. It was proved that the proposed control scheme guarantees that all the variables in the closed-loop system are bounded and the mean-square tracking error can be made arbitrarily small by choosing some design parameters appropriately. Simulation results demonstrated the effectiveness of the proposed robust adaptive control scheme.  
        关键词：nonlinearly parameterized systems;adaptive control;output feedback;unmodeled dynamics;robustness;stability   
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      • Vol. 38, Issue 4, Pages: 141-144(2006)
        摘要：Abstract:Kalman filter is an important method for eliminating stochastic errors of dynamic positioning in GPS/INS integrated navigation system. An optimized algorithm of Dynamic Kalman Filtering for GPS/INS was presented in the paper. Forgetting factor was used to limit remember length of filter. Measurement data was used fully. Computer simulation was done. Computer simulation results showed that as Forgetting factor is increased, the tracking performance of filter is enhanced,and the algorithm is better than general algorithm for extend kalman filtering in dynamic tracking. Positioning precision of GPS/INS can be improved by the algorithm.  
        关键词：GPS;INS;Kalman filtering   
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      • Vol. 38, Issue 4, Pages: 145-149(2006)
        摘要：Abstract:To reduce calculation cost of fusing unequal dimensions measurement vectors,the defect of augmented method which causes high calculation cost was analysed,and a method was presnted which constructs whole measurement space with lower dimensions by physical meanings of measurement data,extends local measurement vectors of unequal dimensions to equivalent in whole measurement space to be fused using combined measurement filtering method. By this method,the limit of combined measurement filtering method was overcomed and the calculation cost of fusing unequal dimensions measurement vectors was reduced.The recursion formula of multisensor minimize variance fusion with correlation was presented too. Simulation results showed that this method has higher fusion accuracy and lower calculation cost than augmented method.  
        关键词：measurement fusion;unequal dimensions measurement vectors;whole measurement space;extend transform   
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      • Vol. 38, Issue 4, Pages: 150-155(2006)
        摘要：Abstract:In order to obtain the original signal contained by noise and transmitted through Internet. A method is introduced which uses the interface between MATLAB and Labwindows/CVI (Virtual instrument programming language ), transferes the program of MATLAB in the server application which is compiled by Labwindows/CVI. The flexible programming ability belong to Virtual instrument programming language and the abundant mathematic tools of MATLAB are well used. Specific signal was extracted from mixed signal by means of one dimensional wavelet packet decomposition and reconstruction with soft threshold and wavelet transform,and the functions of MATLAB was used to analyze the mixed signal frequency spectrum received by Server. Results indicated that this method was feasible.  
        关键词：network virtual instrument;MATLAB;Labwindows/CVI;specific signal;wavelet analysis   
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      • Vol. 38, Issue 4, Pages: 156-161(2006)
        摘要：Abstract:ESPI was proposed to test airflow speckle shift. N frames of speckle patterns along temporal sequence were collected by CCD, phase field of correlated patterns were obtained after calculating the temporal correlated patterns using a FFT program, which does Fourier transformation, filtering, inverse Fourier transformation and phase unwrapping. Then the instantaneous speckle shift could be worked out and the variation process of airflow filed could be also redisplayed. A new experimental analytical method for fast dynamic processes in testing of engineering thermodynamical parameters was put forward.  
        关键词：airflow speckle field;ESPI;contouring fringes;Fourier transformation;speckle shift   
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        发布时间：2023-11-28
      • Vol. 38, Issue 4, Pages: 162-166(2006)
        摘要：Abstract:According to the deformation coordination and force balance condition of shell, the mathematical model to solve the contact pressure between shell and tyre was established. The character of the oblique contact model between kiln roller and tyre was studied, the build-up procedure of oblique contact model between kiln roller and tyre was developed, which is apt to the finite element analysis of roller and tyre under the condition of any load, load rate, oblique angle. By applying uniform design method, the contact finite element calculation scheme between kiln roller and tyre was devised, the stress and deformation of tyre were obtained. The multi-element linear regression was performed, and the fitting formulae of the deformation ovality, the maximum equivalent stress of inner and outer surface of tyre were obtained.  
        关键词：roller and tyre;oblique contact;mechanical property;uniform design method   
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        发布时间：2023-11-28
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