Proposal for a benchmark model of a laminated iron core and a large‐scale and highly accurate magnetic analysis

This paper describes a benchmark model proposed for the clarification of the characteristic of various methods for modeling the laminated iron core. In order to obtain a reference solution of the benchmark model, a large‐scale nonlinear magnetostatic field analysis with a mesh fine enough to represent the microscopic structure of the laminated iron core is carried out by using the hybrid finite element–boundary element (FE‐BE) method combined with the fast multipole method (FMM) based on diagonal forms for translation operators. The computational costs and accuracy of two kinds of homogenization methods are discussed, comparing them with the reference solution. As a consequence, it is verified that the homogenization methods can analyze magnetic fields in laminated iron core within acceptable computational costs. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 26–35, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20809     

Closed-Form Thermoelastic Moduli of a Periodic Three-Phase Fiber-Reinforced Composite

ABSTRACT

In previous works, using the asymptotic homogenization method (AHM), analytical formulae have been obtained for all global elastic constants of a binary fiber composite with perfect interfaces. In many cases of interest the perfect interphase is not an adequate model and it is necessary to include in the analytical models one or more interphases separating the reinforcement inclusion phase from the host matrix phase. In this article, an extension of AHM to thermoelastic heterogeneous problems is given. A simple closed form of effective properties for a three-phase unidirectional transversely isotropic composite is presented. By using homogenization schemes for periodic media, the local problems are solved and effective thermoelastic properties moduli are determined. The method is based on the assumption that the scale ratio between the periodic cell and the whole composite tends to zero. New universal relations for the three-phase thermoelastic composite are found from the AHM. In order to analyze the interphase effect, the effective thermoelastic moduli are compared with some theoretical approaches and experimental results reported in the literature.     

圆形钢筒仓壁厚的计算与探讨

结合工程实例,对圆形钢筒仓壁厚的计算方法进行了分析,并对其合理性和科学性进行了有益的探讨。     

探讨高温均匀化对Ly_(12)硬铝合金板锭塑性的影响

通过高温均匀化试验， 用金相法探讨不同的均热温度对 Ｌｙ１２ 板锭塑性的影响；不同的冷却方式改善 Ｌｙ１２ 板锭的微组织和工艺塑性。     

A hybrid variationally consistent homogenization approach based on Ritz's method

Multiscale approaches based on homogenization theory provide a suitable framework to incorporate information associated with a small‐scale (microscale) problem into the considered large‐scale (macroscopic) problem. In this connection, the present paper proposes a novel computationally efficient hybrid homogenization method. Its backbone is a variationally consistent FE² approach in which every aspect is governed by energy minimization. In particular, scale bridging is realized by the canonical principle of energy equivalence. As a direct implementation of the aforementioned variationally consistent FE² approach is numerically extensive, an efficient approximation based on Ritz's method is advocated. By doing so, the material parameters defining an effective macroscopic material model capturing the underlying microstructure can be efficiently computed. Furthermore, the variational scale bridging principle provides some guidance to choose a suitable family of macroscopic material models. Comparisons between the results predicted by the novel hybrid homogenization method and full field finite element simulations show that the novel method is indeed very promising for multiscale analyses.Copyright © 2013 John Wiley & Sons, Ltd.     

Verification of Homogenization in Fast Critical Assembly Analyses

In the present paper, homogenization procedures for fast critical assembly analyses are investigated.

Errors caused by homogenizations are evaluated by the exact perturbation theory. In order to obtain reference solutions, three-dimensional plate-wise transport calculations are performed. It is found that the angular neutron flux along plate boundaries has a significant peak in the fission source energy range. To treat this angular dependence accurately, the double-Gaussian Chebyshev angular quadrature set with S24 is applied.

It is shown that the difference between the heterogeneous leakage theory and the homogeneous theory is negligible, and that transport cross sections homogenized with neutron flux significantly underestimate neutron leakage. The error in criticality caused by a homogenization is estimated at about 0.1%Δ/k/kk' in a small fast critical assembly. In addition, the neutron leakage is overestimated by both leakage theories when sodium plates in fuel lattices are voided.     

浅谈滑模施工工艺在混凝土筒仓结构施工的应用

本文通过双峰海螺水泥厂生料均化库滑模施工案例，介绍了滑模施工技术及施工要点，希望能够为同类工程施工作业的开展提供一定的参考。     

Stabilization of Water Droplets in an Oily Matrix Exclusively by Gel Formation

As droplets in emulsions are thermodynamically unstable, surfactants are required for their stabilization. However, these additives often are unwanted due to legal restrictions and possible health threats. Gelling of the aqueous phase poses one promising alternative. Only droplet‐forming processes like microfluidic devices are known to successfully work so far for stabilization by gelling. As these processes are hard to scale‐up and tend to foul, a technical alternative based on commonly used high‐pressure homogenization is investigated. A nozzle was adapted by adding a micromixer directly behind the orifice outlet. This allowed gelling and stabilizing the droplets by feeding a cold oil stream immediately after droplet breakup. Up to 40 wt‐% droplets with Sauter mean diameters down to the micrometer range could be successfully stabilized.     

基于储煤筒仓结构中无粘结预应力技术的应用

以山西某煤矿储煤筒仓为例,介绍了无粘结预应力在储煤筒仓结构中的设计方案,从预应力材料控制、无粘结筋的铺设、张拉端预埋处理等方面阐述了无粘结预应力技术在储煤筒仓结构中的施工控制措施,以保证储煤筒仓的安全性和可靠性。