Transport measurements on microcrystals of oriented CeIn3 and CeCoIn5 thin films

We present results of a systematic growth study on the substrate temperature-driven de-wetting of CeIn₃ thin films as a reference compound for the heavy-fermion superconductor CeCoIn₅. This study is motivated by the last results on the improved surface morphology and in-plane orientation preference of c-axis oriented CeCoIn₅ thin films. In apparently phase pure CeIn₃ thin films, as far as x-ray diffraction can tell, we find evidence for minor In segregation by means of percolating resistance contributions of In in the films. We argue that further efforts into improving the films' morphology towards optimized surfaces for the preparation of macroscopic planar tunnel junctions may be futile. As an alternative approach, we present results of electronic transport measurements on CeIn₃ and CeCoIn₅ microcrystals isolated from the thin films by means of focused particle beam induced processing, such as focused ion beam milling and deposition.     

Mechanical analysis of circular liners with particular reference to composite supports. For example, liners consisting of shotcrete and steel sets

This paper describes a methodology for the mechanical analysis of composite supports, such as liners consisting of shotcrete and steel sets. The methodology presented here is based on an established technique of structural analysis commonly referred to as the ‘equivalent section’ approach. This technique consists in treating the composite section of a straight beam as a homogenized section of equivalent mechanical properties. The equations presented in this paper have been derived from application of the theory of elastic shells (or curved beams) and therefore are more appropriate for the analysis of circular tunnel liners. The proposed methodology for the design of liners is based on the construction of capacity diagrams, another established technique of structural analysis and concrete design that can be conveniently extended to the analysis of composite sections for tunnel liners. When applying the theory of elastic shells to derive the equations that conform to the proposed methodology, the problem of determining the mechanical response of semi-circular arches treated with the theory of thin and thick formulations has been re-visited. Observations of practical interest arising from the comparison of results obtained with both approaches are discussed.     

Beam to String Transition of Vibrating Carbon Nanotubes Under Axial Tension

State‐of‐the‐art nanoelectromechanical systems have been demonstrated in recent years using carbon nanotube (CNT) based devices, where the vibration of CNTs is tuned by tension induced through external electrical fields. However, the vibration properties of CNTs under axial tension have not been quantitatively determined in experiments. Here, a novel in situ method for precise and simultaneous measurement of the resonance frequency, the axial tension applied to individual CNTs and the tube geometry is demonstrated. A gradual beam‐to‐string transition from multi‐walled CNTs to single‐walled CNTs is observed with the crossover from bending rigidity dominant regime to extensional rigidity dominant regime occur much larger than that expected by previous theoretical work. Both the tube resonance frequency under tension and transition of vibration behavior from beam to string are surprisingly well fitted by the continuum beam theory. In the limit of a string, the vibration of a CNT is independent of its own stiffness, and a force sensitivity as large as 0.25 MHz (pN)^?1 is demonstrated using a 2.2 nm diameter single‐walled CNT. These results will allow for the designs of CNT resonators with tailored properties.     

弹性基础梁考虑切力对挠度影响时的循环微分辅助函数

文中提出了三组循环微分辅助函数,从而使弹性基础梁考虑切力对挠度的影响时的计算得到很大的简化.     

钢筋砼连续梁优化设计的弯矩分配法

本文首先给出了用各跨最大变矩、最大剪力或跨度表达的单跨钢筋砼梁最优刚度，然后基于分部优化法提出了钢筋砼连续梁优化设计的弯矩分配法，对节点的不平衡弯矩按内力或跨度表达的最优刚度进行一次弯矩分配，手算和电算都很简捷方便。     

集中荷载下高强混凝土无腹筋约束梁剪切破坏特征

本文在进行了十六根高强混凝土无腹筋约束梁试验研究的基础上,综合分析了集中荷载作用下,剪跨内具有反弯点的钢筋混凝土构件斜向开裂的特点和破坏形态.     

前向Beam搜索粗糙集属性约简算法

从属性集互信息的角度分析了粗糙集理论的属性约简问题。粗糙集属性约简通常采用Best-first启发式搜索。本文运用属性集互信息作为属性约简度量，提出了前向Beam搜索粗糙集属性约简算法。实验表明，属性约简算法具有良好的运行效果。     

型钢步进式冷床的改造与实践

主要介绍了柳钢中型连轧生产线型钢步进式冷床的结构特点，并针对原设计和设备管理实践中的问题提出了相应的改进措施和解决办法。     

宽束考夫曼离子源的原理及其使用

宽束考夫曼离子源被广泛地应用于薄膜工艺刻蚀、镀膜、注入诸领域。近20年来考夫曼离子源在我国得到了迅速的发展。至此已有必要提出正确的使用方法。以纠正一些错误的用法。本文给出一些基本概念以利于如何正确选择工作参数以及维修。     

变截面梁的初参数法

本文对任意变化变截面杆,在任意截荷组合下,提出了一个具普遍性的计算公式和计算方法。