In order to minimise the cost of constructing low volume roads (LVRs), it is essential that optimum use is made of locally available, naturally occurring materials. However, conflicts often arise between material acce...In order to minimise the cost of constructing low volume roads (LVRs), it is essential that optimum use is made of locally available, naturally occurring materials. However, conflicts often arise between material acceptability, as defined by conventional test methods and specifications, and material suitability in terms of actual engineering performance as a “fit-for-purpose” road construction material. To avoid such conflicts, it is crucial to adopt appropriate test methods and specifications for selecting construction materials. This paper presents a materials evaluation framework for optimizing the utilisation of materials in LVR pavements based on the use of the Dynamic Cone Penetrometer (DCP). This approach enables materials to be selected on the basis of their “fitness-for-purpose”. It avoids suitable materials from being rejected based on one or other of the traditionally specified parameters not being complied with, even though their strength, as measured by the DCP penetration rate (DN value in mm/blow) of the soil, may be adequate. Investigations of the properties of a wide range of locally available materials that have been used successfully in the construction of LVRs have confirmed the validity of the materials evaluation framework.展开更多
从某飞行器两次飞行记录的俯仰角θ、偏航角Ψ观测值出发,分别采用对Van der Pol方程描述的θ和Ψ的角位移振荡运动微分方程进行气动参数辨识,和对观测值θ-t、Ψ-t曲线的外包络线进行参数拟合两种分析方法,对该飞行器的角位移振荡运动...从某飞行器两次飞行记录的俯仰角θ、偏航角Ψ观测值出发,分别采用对Van der Pol方程描述的θ和Ψ的角位移振荡运动微分方程进行气动参数辨识,和对观测值θ-t、Ψ-t曲线的外包络线进行参数拟合两种分析方法,对该飞行器的角位移振荡运动特性进行了定量分析。两种分析方法取得了较为一致的结果,并证明该飞行器飞行中出现的锥形振荡运动是典型的非线性负阻尼极限环型的振荡运动,获得了非线性负阻尼极限环型气动阻尼力矩的典型表达式。分析结果表明非线性负阻尼极限环类型的气动阻尼能够导致飞行器出现动不稳定。展开更多
In this paper, the rotated cone fitting problem is considered. In case the measured data are generally accurate and it is needed to fit the surface within expected error bound, it is more appropriate to use l∞ norm t...In this paper, the rotated cone fitting problem is considered. In case the measured data are generally accurate and it is needed to fit the surface within expected error bound, it is more appropriate to use l∞ norm than 12 norm. l∞ fitting rotated cones need to minimize, under some bound constraints, the maximum function of some nonsmooth functions involving both absolute value and square root functions. Although this is a low dimensional problem, in some practical application, it is needed to fitting large amount of cones repeatedly, moreover, when large amount of measured data are to be fitted to one rotated cone, the number of components in the maximum function is large. So it is necessary to develop efficient solution methods. To solve such optimization problems efficiently, a truncated smoothing Newton method is presented. At first, combining aggregate smoothing technique to the maximum function as well as the absolute value function and a smoothing function to the square root function, a monotonic and uniform smooth approximation to the objective function is constructed. Using the smooth approximation, a smoothing Newton method can be used to solve the problem. Then, to reduce the computation cost, a truncated aggregate smoothing technique is applied to give the truncated smoothing Newton method, such that only a small subset of component functions are aggregated in each iteration point and hence the computation cost is considerably reduced.展开更多
文摘In order to minimise the cost of constructing low volume roads (LVRs), it is essential that optimum use is made of locally available, naturally occurring materials. However, conflicts often arise between material acceptability, as defined by conventional test methods and specifications, and material suitability in terms of actual engineering performance as a “fit-for-purpose” road construction material. To avoid such conflicts, it is crucial to adopt appropriate test methods and specifications for selecting construction materials. This paper presents a materials evaluation framework for optimizing the utilisation of materials in LVR pavements based on the use of the Dynamic Cone Penetrometer (DCP). This approach enables materials to be selected on the basis of their “fitness-for-purpose”. It avoids suitable materials from being rejected based on one or other of the traditionally specified parameters not being complied with, even though their strength, as measured by the DCP penetration rate (DN value in mm/blow) of the soil, may be adequate. Investigations of the properties of a wide range of locally available materials that have been used successfully in the construction of LVRs have confirmed the validity of the materials evaluation framework.
文摘从某飞行器两次飞行记录的俯仰角θ、偏航角Ψ观测值出发,分别采用对Van der Pol方程描述的θ和Ψ的角位移振荡运动微分方程进行气动参数辨识,和对观测值θ-t、Ψ-t曲线的外包络线进行参数拟合两种分析方法,对该飞行器的角位移振荡运动特性进行了定量分析。两种分析方法取得了较为一致的结果,并证明该飞行器飞行中出现的锥形振荡运动是典型的非线性负阻尼极限环型的振荡运动,获得了非线性负阻尼极限环型气动阻尼力矩的典型表达式。分析结果表明非线性负阻尼极限环类型的气动阻尼能够导致飞行器出现动不稳定。
基金Supported by the National Natural Science Foundation of China (Grant No.10671029)the Research Fund for the Doctoral Programme of Higher Education (Grant No.20060141029)
文摘In this paper, the rotated cone fitting problem is considered. In case the measured data are generally accurate and it is needed to fit the surface within expected error bound, it is more appropriate to use l∞ norm than 12 norm. l∞ fitting rotated cones need to minimize, under some bound constraints, the maximum function of some nonsmooth functions involving both absolute value and square root functions. Although this is a low dimensional problem, in some practical application, it is needed to fitting large amount of cones repeatedly, moreover, when large amount of measured data are to be fitted to one rotated cone, the number of components in the maximum function is large. So it is necessary to develop efficient solution methods. To solve such optimization problems efficiently, a truncated smoothing Newton method is presented. At first, combining aggregate smoothing technique to the maximum function as well as the absolute value function and a smoothing function to the square root function, a monotonic and uniform smooth approximation to the objective function is constructed. Using the smooth approximation, a smoothing Newton method can be used to solve the problem. Then, to reduce the computation cost, a truncated aggregate smoothing technique is applied to give the truncated smoothing Newton method, such that only a small subset of component functions are aggregated in each iteration point and hence the computation cost is considerably reduced.
