肥胖儿童间歇性周期运动下的心肺耐力反应建模分析

当前对肥胖儿童间歇性周期运动下的心肺耐力反应建模分析方法,一般是在运动形式保持不变的情况下,搭建二维动态建模,无法准确给出间歇性周期运动对肥胖儿童的重要性,建模分析准确性较低,且有效性与实用性差。因此,提出准确性和有效性较高的肥胖儿童间歇性周期运动下的心肺耐力反应三维建模分析方法,利用该方法,在不同运动形式的情况下,对肥胖儿童间歇性周期运动下的心率、肺活量指数和最大摄氧量进行三维动态建模,给出三维动态建模分析式,确定间歇性周期运动对肥胖儿童心肺健康的重要性。实验通过对比分析方式,证明所提方法拥有较高的建模分析准确性和有效性。     

FINITE-DIMENSIONAL NON-COMMUTATIVE POISSON ALGEBRAS. II

Here is a structure theorem of a finite-dimensional non-commutative Poisson algebra A. A nice element ε of A will be found, so that the Lie module action of an element of a large Poisson subalgebra of A on A is described in terms of ε and the ordinary associative commutator. Consequently, we can figure out a structure of A when the Jacobson radical rad A satisfies (rad A)² = 0. This structure theorem leads us to a classification of the finite-dimensional simple Poisson A-modules.     

Acoustic and thermal properties of a cellulose nonwoven natural fabric (barkcloth)

The desire to mitigate climate change due to greenhouse gas emissions has led to the exploration of plant fibers as alternative materials for various industrial applications, sound absorption inclusive. In this investigation, sound absorption properties of Antiaris toxicaria barkcloth, and the thermal insulation properties of the barkcloth epoxy laminar composites were characterized. Theoretical sound absorption models were utilized to validate the experimental data and the empirical models were in agreement with experimental data. The lowest thermal conductivity was achieved by the Antiaris toxicaria epoxy composites.     

Modeling nonlinearities of ultrasonic waves for fatigue damage characterization: Theory,simulation, and experimental validation

A dedicated modeling technique for comprehending nonlinear characteristics of ultrasonic waves traversing in a fatigued medium was developed, based on a retrofitted constitutive relation of the medium by considering the nonlinearities originated from material, fatigue damage, as well as the “breathing” motion of fatigue cracks. Piezoelectric wafers, for exciting and acquiring ultrasonic waves, were integrated in the model. The extracted nonlinearities were calibrated by virtue of an acoustic nonlinearity parameter. The modeling technique was validated experimentally, and the results showed satisfactory consistency in between, both revealing: the developed modeling approach is able to faithfully simulate fatigue crack-incurred nonlinearities manifested in ultrasonic waves; a cumulative growth of the acoustic nonlinearity parameter with increasing wave propagation distance exists; such a parameter acquired via a sensing path is nonlinearly related to the offset distance from the fatigue crack to that sensing path; and neither the incidence angle of the probing wave nor the length of the sensing path impacts on the parameter significantly. This study has yielded a quantitative characterization strategy for fatigue cracks using embeddable piezoelectric sensor networks, facilitating deployment of structural health monitoring which is capable of identifying small-scale damage at an embryo stage and surveilling its growth continuously.     

Identification of striking distance considering the velocity ratio and competition among the leaders

The striking distance is an important parameter to design a reliable lightning protection system. To protect an object against direct strikes, an improved leader progression model combined fractal geometry and the leader initiation criteria proposed by M. Becerra is introduced to determine the striking distance on a given structure. Both the deterministic and stochastic features of the lightning leader are considered and more detailed three-dimensional numerical simulation of the leader discharge is achieved due to the application of extended grid. Some of the basic methods and strategies are outlined and the influence on protection zone caused by leader velocity ratio is analyzed. Moreover, a comparative analysis of the results obtained through the improved model, the rolling sphere method and the Cooray model is performed. The results indicate that the presented method is closer to the natural lightning and the selection of the breakdown point is actually a complex competitive process among numerous upward leaders.     

复合张力模糊控制系统设计

张力控制是光纤弹性材料缠绕工艺中的一项关键技术, 它直接影响到缠绕制品的质量。提出一种基于线速度差张力产生原理、微特直流力矩电机为施力机构的复合张力控制系统总体方案,实现对张力的精密控制。在对复合张力控制系统进行了建模分析基础上,模拟真实光纤环缠绕环境,采用模糊控制策略,仿真验证了复合张力控制系统的控制效果,对卷径的变化具有较强适应能力,具有响应快、超调量小、精度高的优点。     

基于VR技术的虚拟校园系统的设计与实现

虚拟现实技术是指利用计算机多媒体技术从人的嗅觉、视觉、触觉和听觉等多方面来全方位模拟环境,使人产生身临其中的感觉,通过人机交互操作,来获得相应的信息或者体验.本文分析了虚拟校园系统的发展现状以及在web2.0下基于VR技术的虚拟校园系统的设计与实现.通过对虚拟现实技术的介绍,结合校园导向标识系统的设计要求,提出利用虚拟现实技术来实现校园导向标识系统的可行性方案.叙述了虚拟校园系统的框架、开发技术以及具体的实现方法,并对虚拟校园系统的建模方法以及交互性进行了重点阐述.     

多视点自由立体显示串扰分析与视区仿真

对多视点自由立体显示的串扰成因进行了分析,推导出了无串扰观看点与光栅参数之间的关系;然后分别对垂直于显示器方向和平行于显示器方向的串扰进行了分析与计算,得到了屏前三维空间的串扰分布情况.仿真结果表明,沿显示屏幕垂直方向的视区范围大于水平方向的视区范围,而且在水平平行于屏幕的方向上,每一个视点存在多个理论无串扰观测点,但在垂直于屏幕方向上,每个视点只存在一个理论无串扰观测点.最后通过对屏前三维区域视点光强进行仿真,进一步验证了串扰计算的准确性,为自由立体显示系统的最佳设计与具体实现奠定了仿真基础.