Resistance of stainless steel CHS columns based on cross-section deformation capacity

A conceptually new structural design approach has recently been proposed by the authors to predict the resistance of stainless steel members subjected to various types of loading with cross-sections formed from thin flat plates including angles, channels, lipped channels, I-sections and rectangular hollow sections (RHS). The proposed method does not follow the traditional cross-section classification approach, which primarily relies on the assumption of a bilinear, elastic-perfectly-plastic material model. Instead, deformation capacity of a cross-section is determined directly from the local buckling characteristics of the constituent plate elements. This is then used to obtain the corresponding local buckling stress utilising an appropriate material model. This basic concept is extended herein to predict compression resistance of stainless steel columns with circular hollow sections (CHS). Available test and finite element (FE) results have been used to develop the basic design equation to predict the compression resistance of cross-sections and to propose column curves to determine flexural buckling resistances. The predicted resistances have been compared to those obtained using the current Eurocode; the predictions are significantly more accurate and more consistent than those given by the existing Eurocode.     

CANDU堆燃料管理程序的物理热工水力耦合和时均计算模型的改进

研制了非线性迭代半解析节块法的扩散程序和稳态单通道热工水力程序,并将二者联接形成了CANDU重水堆燃料管理软件包FMPHWR,实现了物理与热工水力的耦合,参考压水堆(PWR)的经验,提出了类似PWR的考虑局部参数变化的参数化截面方法。对原有的时均计算模型进行了修正,提出了考虑热工水力反馈的时均计算模型,通过数值计算表明：FMPHWR具有更高的计算精度。     

Luminescence properties of Ga-graded Cu(In,Ga)Se2 thin films

Cathodoluminescence (CL) has been measured at 10 K in cross-section and plan-view configuration on Cu(In,Ga)Se₂ thin films with Ga-grading as they are used in high-efficiency solar cells. Measurements on cross-section samples show the vertical profile of the emission energy to correspond to the band-gap profile of the film as calculated from measurements of the Ga-grading. Hence, the CL method is capable to directly measure the band-gap grading in semiconductor thin-films, but often the influence of the grading on the emission energy is generally ignored in recent literature. At the same time, we observe a strong drift of excited charge carriers toward the minimum of the band-gap. The transport process can be explained by the quasi-electric field induced by the Ga-grading and applied to determine transport properties of the Cu(In,Ga)Se₂ material. Implications for luminescence investigations on band-gap graded thin-films are discussed.     

Investigation on a new type of low-stress cropping system with variable frequency vibration

This paper presents a new type of precision cropping system with variable frequency vibration by which the high-quality cutting surface can be obtained. On the basis of D’Alembert’s principle, the approximate relationship between the exciting force and the excited frequency in the cropping is acquired through computation. Five types of excited frequency control curves are designed and applied in the cropping experiments and the influences of these control curves on the cropping cross-section and the cropping time are investigated by experiment in details. According to the special feature of the cross-section obtained in the course of variable frequency vibration cropping, a new measurement method is proposed and applied to assess the quality of the cross-section. The theoretic and experimental results show that the exciting force acted on the bar in the vertical direction is larger than that in the horizontal direction and the linear decrease control curve, by which the high quality cross-section is obtained and the cropping time is reduced, is an ideal control mode compared with other control modes mentioned in the paper. The experiment also proves that the width of the bar instantaneous fracture region is decreased by reducing the value of every step frequency change, and the cropping time is also shortened by reducing the durative time of every step variable frequency under the action of the linear decrease frequency curve.     

冲床中心线定位装置

对比了以往电动机驱动左右旋丝杠对中形式和以气缸、同步带对中形式的优点和缺点,并采用伺服电动机驱动丝杠来适应变截面纵梁,提高设备的冲压精度。     

带加劲肋方钢管混凝土柱的静力特性

方钢管内填混凝土柱(CFSTs)在现代建筑中的使用越来越广泛,与钢柱和混凝土柱相比,其材料性能和功效均有所提高。然而,尽管方钢管混凝土柱的屈曲特性优于中空钢管,由于局部屈曲,其外包钢管截面的高厚比仍受到限制。针对外包钢管带加劲肋的方钢管混凝土柱,提出了一些新的加劲肋形式。为评估这些加劲肋对方钢管混凝土柱力学性能的影响,并与传统加劲肋进行比较,该文对4个带不同加劲肋的方钢管混凝土柱和1个无加劲肋方钢管混凝土柱进行了试验。试验研究了材料的抗力、延性和失效模式等力学性能,为了对试样的综合性能进行预测和总结,也从理论上对这些力学性能进行了研究。为了解各参数对力学性能的影响,该文进行了数值模拟和大量的参数研究,相关学者的试验数据验证了数值分析结果的准确性。基于试验结果和以往的研究,提出了截面强度的设计建议。     

基于研磨抛光切片技术的芯片结构观察研究

芯片结构观察广泛应用于芯片的生产、工艺改进、失效分析和可靠性等领域。芯片结构分为剖面结构和表面各层结构,对芯片进行切片是观察其内部结构的一种较为简便的方法。研磨抛光切片是一项低成本的切片技术,但由于精度较低、操作复杂,较少应用于芯片的结构观察。详细说明了研磨抛光切片技术的原理,给出了改进后的切片工艺,并通过实例说明该方法在芯片剖面结构观察和表面各层结构观察中的应用。该方法可满足大部分情况下对芯片结构观察的需要。讨论了该技术目前存在的问题。     

澳毛粘胶涤纶混纺纱的开发

介绍了在棉纺设备上开发生产澳毛／粘胶／三角形截面异形涤纶20／60／2018．5tex混纺纱的工艺流程和生产技术措施。澳毛／粘胶／三角形截面异形涤纶20／60／2018．5tex采用分别制条，在并条混和的纺纱工艺流程。     

An energy recondensation method using the discrete generalized multigroup energy expansion theory

In this paper, the discrete generalized multigroup (DGM) method was used to recondense the coarse group cross-sections using the core level solution, thus providing a correction for neighboring effect found at the core level. This approach was tested using a discrete ordinates implementation in both 1-D and 2-D. Results indicate that 2 or 3 iterations can substantially improve the flux and fission density errors associated with strong interfacial spectral changes as found in the presence of strong absorbers, reflector of mixed-oxide fuel. The methodology is also proven to be fully consistent with the multigroup methodology as long as a flat-flux approximation is used spatially.     

Influence of operational parameters on the performance of PEMFCs with serpentine flow field channels having different (rectangular and trapezoidal) cross-section shape

The effect of operational parameters on the performance of PEMFCs by using serpentine flow field channels with different (rectangular and trapezoidal) cross-section shape has been investigated. More than cell temperature and pressure, reactant humidification temperature (T_ha,c) has a significant influence on the effect of serpentine channels with trapezoidal cross-section on cell performance. The high capability of water removal by serpentine channels with trapezoidal cross-section positively affects the fuel cell performance when the water content in the system is high, as in the case of the reactant humidification temperature higher than cell temperature (T_c). On the contrary, when the water content in the cell is low, as in the case of T_ha,c = T_c, the high ability of water removal of serpentine channels with trapezoidal cross-section results in a less effective membrane/cathode hydration. Conversely, the effect of T_ha,c on the performance of the cell with serpentine channels with rectangular cross-section is negligible.