共查询到20条相似文献,搜索用时 46 毫秒
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《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2009,37(11):2250-2256
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贡梨是大众喜爱的水果,为研究不同检测方向对近红外在线检测贡梨可溶性固形物SSC的影响,提出全局模型并分析其鲁棒性。在贡梨六个方向上收集光谱:茎-花萼轴垂直,茎向上(A1)和茎向下(A5),茎-花萼轴和水平之间45°,茎向上倾斜(A2)和茎向下倾斜(A4),茎-花萼轴水平,茎朝向右侧光(A3),茎花萼轴水平,茎朝向带移动方向(A6)。SSC范围为9.53~14.70的150个样品分为115个标准偏差为1.05的校准集和35个标准偏差为0.93的预测集。采用偏最小二乘回归PLSR分别建立六个局部模型和一个全局模型,局部模型由各方向的115个校正集数据经过Savitzky-Golay卷积平滑、多元散射校正MSC、高斯滤波平滑GFS三种不同的预处理方法处理后使用偏最小二乘回归PLSR建立而来;用本方向校正集数据建立的局部模型验证本方向的35个预测集数据,比较这三种预处理方法后所建立的PLSR模型,结果表明经过GFS处理后建立的模型验证效果最好,因此六个局部模型和全局模型均采用GFS处理后建立的PLSR模型。全局模型是由A1, A2, A3, A4, A5和A6六个方向的690个校正集光谱数据经... 相似文献
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A lumped thermal model was developed in order to analyse the transient gas temperature rise and fall in a dielectric barrier discharge reactor. A laboratory reactor was employed to validate the model by means of the experimental data. It has been shown that this simple model is of sufficient accuracy for engineering applications. 相似文献
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V. Ya. Basevich A. A. Belyaev V. S. Posvyanskii S. M. Frolov I. V. Semenov 《Russian Journal of Physical Chemistry B, Focus on Physics》2007,1(5):493-499
A mathematical model of steady laminar flame propagation through a suspension of liquid droplets was proposed, and numerical calculations within the framework of this model were performed. The model is constructed based on one-dimensional differential equations of the theory of laminar flames in homogeneous gaseous mixtures in conjunction with the theory of droplet burning in uniform monodisperse suspensions. The chemical process was described using a multistage kinetic scheme. A comparison of model predictions with the available experimental data demonstrated satisfactory agreement. 相似文献
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A model for negative glow corona discharge in a coaxial electrode configuration is presented. The main goal of this model is to describe the influence of a more efficiently electron-attaching gas on the distribution of free electron density in the drift region. The calculated distributions of electrons and other ionic components are shown. The model was applied in experiments realized in air + freon mixtures. A qualitative agreement between theoretical and experimental results was achieved. 相似文献
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Velocity distributions within three models of the human larynx, namely, a rigid plexiglas model, an excised canine larynx, and a computational model are investigated with experimental and theoretical analyses. A plexiglas wind tunnel with interchangeable glottal constrictions was used as a two-dimensional steady-flow model to measure velocity and pressure for various glottal shapes. A canine excised larynx was used as a prototype pulsatile flow model to study pressure and velocity variations during phonation. Results of the plexiglas modelling indicated a parabolic laminar velocity profile upstream of the glottal constriction and turbulent and asymmetric velocity profiles downstream of the glottal constriction. The time-averaged velocities of the excised larynx had similarities with the plexiglas model results, and instabilities and asymmetries were also demonstrated by the computational method. 相似文献
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A polarisable model for acetone, COS/A, is proposed that is based on the charge-on-spring (COS) polarisation model and is compatible with the polarisable COS/D2 and COS/G2 models for liquid water. A series of acetone-water mixtures at different acetone mole fractions was simulated using the new model in conjunction with the mentioned polarisable and the non-polarisable SPC and SPC/E water models. The model was parameterised to reproduce the following liquid acetone properties: density, heat of vaporisation, surface tension, dielectric permittivity, self diffusion and heat capacity and subsequently tested in mixtures with water using different water models. For pure liquid acetone the polarisable COS/A model agrees better with experimental data than the non-polarisable Kirkwood-Buff derived force field (KBFF) model, which was parameterised using experimental data for a 0.5 mole fraction acetone-water mixture. For such mixtures the polarisable models yield better agreement with experiment than the non-polarisable models for the heat of vaporisation and dielectric permittivity, while worse agreement for diffusion. The computational cost of simulating the polarisable acetone-water mixtures is a factor of 3 to 4 higher compared with the non-polarisable models due to the increased number of interaction sites and the multiple iterations required to evaluate self-consistently the positions of the COS sites at every simulation step. The COS/A acetone model can be used in biomolecular simulations in conjunction with the mentioned polarisable water models to solvate biomolecules. 相似文献
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An anatomically analogous distributed parameter dynamic model of the human arm is proposed and quantitatively validated. Distributed mass and stiffness parameters have been obtained by representing each long bone of the arm as a flexural beam. A distributed damping parameter was introduced by allowing the beam stiffness to be a complex quantity. Hand properties were modelled as a lumped parameter damped spring-mass system. Mechanical driving point impedance techniques were used to verify the model. A dual beam model of the forearm was first proposed, and its frequency response was compared with impedance data collected on the forearm. After having established the validity of the forearm model, it was then extended to include the upper arm. The frequency response of the whole-arm model was then compared with impedance data on the whole arm collected by a previous investigator. It is concluded that the beam model of the human arm adequately represented its dynamic behavior as measured by mechanical driving point impedance techniques. The amount of information concerning the dynamic behavior of the arm yielded by the distributed parameter model is found to be vastly greater than that yielded by lumped parameter models. 相似文献
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S. M. Frolov V. Ya. Basevich F. S. Frolov A. A. Borisov V. A. Smetanyuk K. A. Avdeev A. N. Gots 《Russian Journal of Physical Chemistry B, Focus on Physics》2009,3(3):333-347
A parametric analysis of numerical solutions to problems of vaporization and self-ignition of liquid hydrocarbon drops was performed, and a new criterion determining the conditions of drop self-ignition was suggested. According to this criterion, self-ignition at a given reduced distance from the drop begins when the required reduced gas temperature and equivalence ratio are reached. A new model of heating and vaporization of drops in dense gas suspensions was suggested. The model was verified in multidimensional calculations of self-ignition and combustion of drop clouds. Calculations showed that the model correctly described the phenomenology of local formation and anisotropic propagation of self-ignition waves in suspensions of drops in gases. 相似文献
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Yan Liu & Hejun Du 《advances in applied mathematics and mechanics.》2011,3(6):716-728
Ramp load/unload (L/UL) mechanisms are widely used to rest sliders in hard disk drives (HDDs).
Loading/unloading a slider swiftly and smoothly is crucial in a HDD design. A novel, efficient
simulation scheme is proposed to investigate the behaviors of a head disk interface (HDI) in
ramp unloading processes. A dual scale model is enabled by decoupling the nano-meter scale change
of an air bearing and the micro- or milli-meter scale deformation of a suspension. A modified
Reynolds equation governing the air bearing was solved numerically. The slider design was
characterized with performance functions. Three stages in an unloading process were analyzed
with a lumped parameter suspension model. Key parameters for the model were estimated with a
comprehensive finite element suspension model. Finally, simulation results are presented for
a commercial HDI design. 相似文献
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An analytical theory of cylindrical low-contrast Bragg optical waveguides, i.e., Bragg fibers, was developed on the basis of the representation of thin diffuse layers by delta functions. A dispersion relation for the Bragg optical waveguide with a finite number of layers was derived in the scalar approximation. Mode fields and losses were numerically calculated for a fiber with parameters close to those of actual fiber known from the literature. A comparison with the planar model was performed, which showed significant qualitative similarity. The presented model of Bragg fibers is more realistic than the model with sharp layer boundaries. 相似文献
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《Physica A》2007,378(2):211-222
A zero-dimensional nonlinear evolution model is derived from the full set of two-dimensional fluid evolution equations of the curvature driven Rayleigh Taylor instability. Such a model, arrived on heuristic grounds earlier, was found to capture the principal features of the final saturated state of the instability [A. Das, S. Mahajan, P. Kaw, A. Sen, S. Benkadda, A. Verga, Phys. Plasmas 4 (1997) 1018; A. Das, A. Sen, S. Mahajan, P. Kaw, Phys. Plasmas 8 (2001) 5104]. We present a detailed analysis of the linear and nonlinear characteristics of the model and also discuss some of its limitations. 相似文献
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在考虑自由体积和局部临界扩散势能的基础上,提出一种新的计算自扩散系数模型,并给出新模型中各个因子物理含义.同时还提出一种计算局部临界扩散势能的新方法,并应用于新模型.另外将衍生van der Waals状态方程应用于求解自由体积,式中所需径向分布函数由Morsali-Goharshadi方程得到.在相同条件下,新模型比原自由体积模型更准确. 相似文献
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A peculiar bifurcation phenomenon in the diffraction spectra of volume holograms is investigated. A linear expansion model modulated by a random number was built to explain the phenomenon. In our model, a random number was first introduced to describe the random property of swelling or shrinking of the emulsion during the process after exposure. The calculated results show good consistency with the experimental observations. 相似文献
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通过分析现场生产数据和数值模拟结果,将薄层稠油油藏蒸汽辅助重力驱油(SAGD)生产中蒸汽腔发育分为横向扩展和向下运移两个过程,并进行简化处理预测SAGD生产指标.联合质量守恒方程、能量守恒方程和周围地层散热模型得到一个描述蒸汽腔发育的综合表达式,该方程属于典型的第二类Volterra积分函数.通过拉普拉斯变换对Volterra积分函数进行半解析求解,最终得到不同时刻蒸汽腔发育状态.为验证模型的正确性,将模型的计算结果与CMG Stars的计算结果对比,整体误差小于5%.新模型可以方便简单地预测SAGD生产中蒸汽腔发育过程和生产动态指标,从而确定SAGD生产的极限油藏参数和合理的注采参数. 相似文献