轴向运动弦线横向振动的频域分析

轴向运动弦线是多种工程系统的模型。为明确轴向运动横向振动的频域特性，及探索频域方法的应用特点．本文用频域方法分析轴向运动弦线的横向振动。基于轴向运动弦线横向振动方程和边界条件．通过Laplace变换导出频率域中的控制方程，并将该控制方程和边界条件用状态变量表示。由状态空间中的控制方程导出特征方程，从而求出固有频率。由轴向运动弦线的矩阵函数计算得到系统的传递函数，然后用留数定理计算传递函数的Laplace逆变换．这样就可以得到时域响应。最后分析了轴向运动弦线的横向共振，若简谐外激励的频率与系统固有频率相同，系统响应将随时间无限增加。     

Application of the phase‐type mortality law to life contingencies and risk management

The class of phase‐type distributions has recently gained much popularity in insurance applications due to its mathematical tractability and denseness in the class of distributions defined on positive real line. In this paper, we show how to use the phase‐type mortality law as an efficient risk management tool for various life insurance applications. In particular, pure premiums, benefit reserves, and risk‐loaded premiums using CTE for standard life insurance products are shown to be available in analytic forms, leading to efficient computation and straightforward implementation. A way to explicitly determine provisions for adverse deviation for interest rate and mortality is also proposed. Furthermore, we show how the interest rate risk embedded in life insurance portfolios can be analyzed via interest rate sensitivity index and diversification index which are constructed based on the decomposition of portfolio variance. We also consider the applicability of phase‐type mortality law under a few non‐flat term structures of interest rate. Lastly, we explore how other properties of phase‐type distributions may be applied to joint‐life products as well as subgroup risk ordering and pricing within a given pool of insureds. Copyright © 2017 John Wiley & Sons, Ltd.     

封闭水浴溶样-载碳泡塑吸附-电感耦合等离子体发射光谱法测定矿石中金含量

采用聚碳酸酯溶样瓶进行封闭水浴溶样,溶液加入NH_4HF_2和酒石酸配合其它干扰金属阳离子,加入载碳泡塑振荡吸附金,使用电感耦合等离子体发射光谱仪(ICP-OES)直接测定.方法检出限为0.005 09μg/g,测定上限为150.0μg/g,相对标准偏差(RSD)低于5.77%,消除了Ag、Sb和Fe等阳离子干扰,通过对不同含量金矿石标准物质的测定,取得了较高的准确度,可满足金矿石分析要求.     

The new solution for the axially symmetrical laminar boundary layer equations between two parallel sherical surfaces

The transformations, which are similar to Mangler’s transformations, are given in this paper. They change the entrance region flow of axially symmetrical laminar boundary layer between two parallel spherical surfaces into the flow of two-dimensional boundary layer, and simplify the problems. The simplified equations can be solved by the two-dimensional boundary layer theory and numerical methods. Therefore, a new way is opened up to solve the diffusive laminar flow in the entrance region between two parallel spherical surfaces.     

Moving antiplane shear crack in hexagonal piezoelectric crystals

Closed-form solutions are obtained and discussed for the stress and electric displacement fields around a loaded Griffith-type antiplane shear strip crack moving in hexagonal piezoelectric crystals. Representative numerical results are presented for ZnO and PZT-4.     

Analysis of graphene based optically transparent patch antenna for terahertz communications

With and without multi walled carbon nanotube (MWCNT) loaded graphene based optically transparent patch antennas are designed to resonate at 6 THz. Their radiation characteristics are analyzed in 5.66–6.43 THz band. The optically transparent graphene is deployed as the patch and ground plane of the antennas, which are separated by a 2.5 μm thick flexible polyimide substrate. By shorting the microstrip line and ground plane of the antenna with a MWCNT via, the return loss of the antenna is improved. The peak gain of 3.3dB at 6.2 THz and a gain greater than 3dB in 5.66–6.43 THz band is obtained for antenna loaded without MWCNT. Both the antennas achieved a −10dB impedance bandwidth of 12.83%. Gain, directivity and radiation efficiency of the proposed antennas are compared with conventional transparent patch antennas and graphene based non-transparent antennas. The antenna structures are simulated by using finite element method based electromagnetic simulator-Ansys HFSS.     

Dispersion Characteristics of Dielectric Loaded Multiple V-Ridge Waveguide

A new kind of V-ridge waveguide is presented in this paper. The transmission problem is solved by edge element for the first time. The field patterns of the waveguide with single, double and triple V-ridge for different values of dielectric constant have been presented. Variations of the cutoff wavelength, single-mode bandwidth with the ridge dimensions for different values of dielectric constant are investigated in detail. The results will be of practical significance in designing ridge waveguide components in microwave and millimeter wave engineering.     

Experimental Dissection of the Column Efficiency in Gradient Column

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Investigation of the Column Function in Gradient Column

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Nonlinear three-dimension analysis for axially symmetrical circular plates and multilayered plates

Analytic nonlinear three-dimension solutions are presented for axially symmetrical homogeneous isotropic circular plates and multilayered plates with rigidly clamped boundary conditions and under transverse load.The geometric nonlinearily from a moderately large deflection is considered.A developmental perturbation method is used to solve the complicated nonlinear three-dimension differential equations of equilibrium.The basic idea of this perturbation method is using the two-dimension solutions as a basic form of the corresponding three-dimension solutions,and then processing the perturbation procedure to obtain the three-dimension perturbation solutions.The nonlinear three-dimension results in analytic expressions and in numerical forms for ordinary plates and multilayered plates are presented.All of the plate stresses are shown in figures.The results show that this perturbation method used to analyse nonlinear three-dimension problems of plates is effective.