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971.
针对音频信号准确性分类的问题,提出一种基于改进的的粒子群优化算法(PSO)的支持向量机(SVM)音频信号分类的方法,简称IPSO-SVM.首先用Mel倒谱系数法对4种音频信号进行特征提取.其次在PSO中引入自适应变异因子,能够成功地跳出局部极小值点;然后对PSO中的惯性权重进行了改进,将惯性权重由常数变为指数型递减函数.随着迭代的进行,使权重逐渐减小,这样做有利于粒子进行局部寻优.最后用改进的PSO不断优化SVM中的惩罚因子c和核函数参数g来提高预测精度.实验结果表明,与传统的SVM、PSO-SVM、GA-SVM相比,我们提出的IPSO-SVM算法分类结果更精确. 相似文献
972.
准确预测风电场风速是解决风能对电力系统所造成的安全、稳定运行和电能质量等问题的有效途径之一.风速的难以预测是由于它的高度随机和非线性.基于一种非参数的非线性自回归随机模型来预测风速,模型的自回归系数随模型依赖变量的变化而变化,因而它有灵活的非线性结构.数值实验和比较结果表明了这种函数系数自回归模型在风电场风速预测中的有效性. 相似文献
973.
the measurements of flow over non-uniform gravel open channel have been conducted with Laser Doppler Velocimetry (LDV). The experimental results indicate that the distribution of mean velocity agrees well with the Nikuradse's law. From the distributions of resistance coefficient, reference level and turbulence intensity, the classification of small scale roughness case is obtained.Project supported by the National Science Foundation of China 相似文献
974.
The nonstationary rectilinear motion of an amphibian air-cushion vehicle (AACV) on a water surface covered with finely broken ice is considered for various modes of velocity variation. The influence of
the water depth, flotation parameters, and mode of motion on the wave resistance of the vehicle is analyzed. Maneuvering methods
for increasing or decreasing the wave resistance of AACVs are proposed.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 1, pp. 97–102, January–February, 2007. 相似文献
975.
976.
A compartmental model is developed to estimate flow parameters of a shallow aquifer affected by water loads in surface reservoirs and to evaluate its nonsteady flow distribution. The method incorporates temporal piezometric head measurements and sampling of water for dissolved chemicals and isotopes analyses. Each compartment is governed by a set of equations describing the conservation of linear momentum and mass balance expressions for water, isotopes, and dissolved chemicals. The number of compartmental balance expressions always must be greater than that of the unknown flow parameters associated with each compartment. An optimization method is described to yield spatial distribution of aquifer storativity, transmissivity, porosity, leakage, and compliance coefficients and fluxes leaking into an aquifer's lower boundary. Future predictions of an aquifer's piezometric head distribution in a compartmental system is formulated on the basis of the estimated flow parameters and the leakage components.Compartmental modelling which incorporates concentrations of environmental tracers, may yield efficiency in computing resources and accuracy enhancement for predicting an aquifer's flow regime. 相似文献
977.
Qing Lu N.V. Suryanarayana Christodoulous Christodoulu 《Experimental Thermal and Fluid Science》1993,7(4):354-361
A technique for measuring condensate film thickness using an ultrasonic transducer is described. In the experiment, the condensate film thickness with R-113 and FC-72 (a fluorinert compound developed by the 3M Company) condensing on the horizontal lower surface of a rectangular duct was measured at several locations. From the measured values a power law relation between the condensate film thickness and the axial distance from the leading edge of the condensing surface was derived by regression analysis. Assuming a linear temperature profile in the condensate film, local and average heat transfer coefficients were computed from the condensate film thickness. The average heat transfer coefficients were compared with the values obtained by measuring the heat transfer rate to the coolant. The two values were within ±12% of each other. As yet there is no satisfactory analytical model to predict the local heat transfer coefficient even in the annular condensation regime. One of the main difficulties in modeling the condensation is the lack of a suitable model to predict the interfacial shear stress. With the measurement of the film thickness it is possible to determine the interfacial shear stress. It is hoped that the shear stresses so determined will lead to the development of a satisfactory model for interfacial shear stress with condensation. 相似文献
978.
979.
高温封隔器胶筒与套管接触压力的实验研究 总被引:13,自引:0,他引:13
本文利用所研制的高温封隔器测试装置,应用高温电阻应变测试技术与有限元相结合的方法,研究了油井高温封隔器胶筒与石油套管内壁接触压力大小和分布规律,为优化高温封隔器的设计,提供有价值的数据。 相似文献
980.
用正交旋转试验设计,建立了一种比多元线性回归设计更简明的水基高分子润滑剂摩擦系数的数学模型.通过摩擦系数的响应曲面分析,可以确定润滑剂配方中各组分用量变化的优化水平,用图示法分析各组分间的交互作用和它们对润滑剂质量指标的影响.此外,利用响应曲面分析法还可为研究多组分复配润滑剂的润滑性能提供数理依据 相似文献