Analytical solutions for nonlinear analysis of composite single-lap adhesive joints

This paper presents analytical nonlinear solutions for composite single-lap adhesive joints. The ply layups of each composite adherend can be arbitrary, but in the overlap region the ply layups of the upper and lower adherends are assumed to be symmetrical about the adhesive layer. In the present formulation, equilibrium equations of the overlap are derived on the basis of geometrical nonlinear analysis. The governing equations are presented in terms of adherend displacements by taking into account large deflections of the overlap adherends and adhesive shear and peel stresses simultaneously. Closed-form nonlinear solutions for adherend displacements, an edge moment factor and adhesive stresses are formulated and then simplified for practical applications. To verify the present analytical solutions for nonlinear analysis of composite single-lap joints, the geometrically nonlinear 2D finite element analysis is conducted using commercial package MSC/NASTRAN. The numerical results of the edge moment factor, deflections and adhesive stresses predicted by the present solutions correlate well with those of the geometrically nonlinear finite element analysis. This indicates that the present analytical solutions capture key features of geometrical nonlinearity of composite single-lap adhesive joints.     

Development of Hydropower Resources in Southwest China

There is a boom of hydropower development in Southwest China recently because of the abundant hydropower resources there, especially in Yunnan and Sichuan provinces, which has attracted the attentions of various major power generation companies and private enterprises. Based on the situation of hydropower development in the Southwest and combined with the analysis of prospective receiving market and the capability of electrical and mechanical equipment’s manufacturing, this paper discusses the main problems...     

Balancing reduction of linear systems having multiple delays

Abstract

In this paper we apply the balancing reduction method to derive reduced‐order models for linear systems having multiple delays. The time‐domain balanced realization is achieved through computing the controllability and observability gramians in the frequency domain. With the variable transformation s = i tan(θ/2), the gramians of linear multi‐delay systems can be accurately evaluated by solving first‐order differential equations over a finite domain. The proposed approach is computationally superior to that of using the two‐dimensional realization of delay differential systems.     

The characteristics of voltage degradation of a proton exchange membrane fuel cell under a road operating environment

A real-life testing experiment of a proton exchange membrane fuel cell (PEMFC) and the basic characteristics of its voltage degradation are presented. A general package radio system (GPRS)-based remote monitoring system was used as the data acquisition method, and the non-linear regression method was used to estimate PEMFC's polarization curve within specific iso-interval periods. The voltage degradation rate was calculated using the differential method, and its average level was also analyzed. The experimental results indicated that the voltage degradation rate at a specific current density featured a bathtub-like curve, exhibiting 1) infant degradation, 2) steady degradation, 3) and accelerated degradation.     

CAP1400钢制安全壳现场组装焊接质量控制

从加强核电现场焊接质量管控的角度出发,通过对CAP1400压水堆核电钢制安全壳现场组装焊接过程中质量控制的论述,提出了一套较为全面的现场焊接质量控制流程。从母材及焊材的选择为出发点展开分析,结合现场焊接实际状况,对焊接质量控制容易忽视的薄弱环节,提出了具有针对性的处理方案,提高了钢制安全壳拼装过程中的焊缝质量,同时对现场产生的不符合项处理流程的优化提出了改进意见。     

Automatic small blend recognition from B-rep models for analysis

The recognition and suppression of small features from B-rep models play an important role in effectively generating the qualified mesh for analysis. This paper presents a new algorithm for recognizing small blends automatically for the purpose of mesh generation. The algorithm first transforms the input B-rep model into an aggregation of faces. Then, each face is judged to be a blend or not based on matching conditions. At last, the blends with larger physical sizes than a threshold value are excluded. The innovations lie in the recognition conditions and the unique calculating procedure of the blend physical size. Several examples are given to demonstrate the validity and applicability of the algorithm.     

An S-shaped relationship between changes in appraisals and changes in emotions.

Previous research on appraisal theories of emotion has shown that emotions and appraisals are related but has not specified the nature of the relationships. This research examined the functional forms of appraisal-emotion relationships and demonstrated that for all seven appraisals studied, appraisals relate to emotions in an S-shaped (ogival) fashion: Changes in appraisals at extreme levels are associated with only small changes in emotions, but changes at moderate levels are associated with substantial changes in emotions. With a few exceptions, ogival relationships were found for the relationships between seven appraisals (Goal Achievement Expectancy, Agency, Control, Certainty, Fairness, Pleasantness, and Motive Congruence) and numerous relevant emotions across different sample-types, cultures, and methods. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bang-Bang Control Class D Amplifiers: Total Harmonic Distortion and Supply Noise

The total harmonic distortion (THD) and the power supply noise, qualified by the power supply rejection ratio (PSRR) and by the power supply induced intermodulation distortion (PS-IMD), are recognized to be potential drawbacks of class D amplifiers. In this paper, analytical expressions for the THD, PSRR, and PS-IMD of the bang-bang control class D amplifier (bang-bang amp) are derived; the bang-bang amp is arguably the most power-efficient class D amp for low-voltage power-critical applications including hearing aids. Based on the derived expressions, the effects of important parameters on the THD, PSRR, and PS-IMD are investigated, providing good insight to the design of the bang-bang amp to meet given design specifications. The analytical analyses are verified by comparing them against HSPICE simulations and hardware measurements. The bang-bang amp is also compared against the prevalent pulsewidth modulation class D amp, and in most cases, the former is shown to possess superior parameters, including lower power dissipation and hardware advantages for low-voltage power-critical applications.     

基坑围护中SMW工法的应用

结合工程实例,简要介绍了基坑围护结构SMW工法在施工过程中的各施工要点及该施工工艺的特点。     

Facile synthesis and luminescent properties of Y2O3:Eu3+ nanophosphors via thermal decomposition of cocrystallized yttrium europium propionates

Y₂O₃:Eu³⁺ nanophosphors were fabricated by direct thermal decomposition of monohydrate yttrium europium propionates, which can be facilely obtained via cocrystallization. The composition and structure of the cocrystallized product were confirmed by X-ray diffractionmetry (XRD), simultaneous differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) as well as inductively coupled plasma mass (ICP-MS) spectrometry. The effects of decomposition temperature on the resultant microstructures such as crystallinity, particle size and particle dispersibility were investigated by XRD and transmission electron microscopy (TEM). The dependence of their luminescent properties on decomposition temperature was also studied by fluorescence spectrophotometry. The results showed that the microstructures and luminescent intensities of Y₂O₃:Eu³⁺ nanophosphors could be tuned by varying calcination temperatures of cocrystallized yttrium europium propionates from 600 to 1000 °C.