The Direct Heat Measurement of Mechanical Energy Storage Metal–Organic Frameworks

In any process, the heat exchanged is an essential property required in its development. Whilst the work related to structural transitions of some flexible metal–organic frameworks (MOFs) has been quantified and linked with potential applications such as molecular springs or shock absorbers, the heat related to such transitions has never been directly measured. This has now been carried out with MIL‐53(Al) using specifically devised calorimetry experiments. We project the importance of these heats in devices such as molecular springs or dampers.     

多股簧的设计计算及有限元仿真分析

根据多股簧的成形过程,分析了单股钢丝中心线的空间结构,在现有几何参数基础上计算了钢索分布圆半径、钢丝螺旋倍数和钢丝中心线的轨迹扫描参数。提出了基于特征扫描的多股簧辅助设计方法,通过一个扫描步即可得到多股簧单股钢丝中心线的模型,并给出了基于PROE软件的建模方法。在上述多股簧设计计算的基础上,采用模型结果,给出了多股簧加载过程中弹簧和钢丝应力应变特性的ABAQUS有限元仿真分析。分析结果显示了多股簧承载时钢丝的应力应变特性、钢丝截面的应力分布情况、加载速率对多股簧簧圈振动的影响,弥补了现有多股簧分析和测试手段的不足,为多股簧的生产加工和性能实验提供有效的指导。     

Multiscale mass-spring models of carbon nanotube foams

This article is concerned with the mechanical properties of dense, vertically aligned CNT foams subject to one-dimensional compressive loading. We develop a discrete model directly inspired by the micromechanical response reported experimentally for CNT foams, where infinitesimal portions of the tubes are represented by collections of uniform bi-stable springs. Under cyclic loading, the given model predicts an initial elastic deformation, a non-homogeneous buckling regime, and a densification response, accompanied by a hysteretic unloading path. We compute the dynamic dissipation of such a model through an analytic approach. The continuum limit of the microscopic spring chain defines a mesoscopic dissipative element (micro-meso transition) which represents a finite portion of the foam thickness. An upper-scale model formed by a chain of non-uniform mesoscopic springs is employed to describe the entire CNT foam. A numerical approximation illustrates the main features of the proposed multiscale approach. Available experimental results on the compressive response of CNT foams are fitted with excellent agreement.     

减压阀主阀弹簧参数的计算机辅助图解法

减压阀主阀弹簧的刚度和预压缩量值是减压阀静态特性计算的一项重要内容。本文介绍了一种计算机辅助图解法，它以ＡｕｔｏＣＡＤ的高级绘图功能为基础，利用Ａｕｔｏｌｉｓｐ编制有效的设计计算与图形自动生成程序，对减压阀主阀弹簧的刚度与预压缩量进行求解。     

An Exact Solution of Torsion Problem for an Incomplete Torus with Application to Helical Springs

An exact analytical solution for the torsion problem of an incomplete torus with a particular form of non-circular cross-section has been found. The solution extends for the close-coiled helical spring the known solution of the torsion problems for straight cylinders with circular and elliptical cross-sections. The pitch of helix is ignored. The hollow cross-sections of the particular form also demonstrate a closed form of analytical solution. The solution can be used for analysis of helical springs with non-circular wire profile.     

Sensitive and rapid determination of elemental nanosulfur/sulfur by liquid chromatography

In order to identify the most suitable method for the estimation of nanosulfur for studying its residue dynamics, the present work was taken up. HPLC and GC methods were explored for its analysis. A comparative study of the existing analytical methods for the quality control of nanosulfur was undertaken. UV spectrophotometry and HPLC methods were superior with lower LOD when compared to GC–MS, which was not satisfactory due to breakage of catenated S₂₀ into S₆ and S₈. The method has been validated by analyzing various nanosulfur formulations of known concentrations. The recovery of the UV and HPLC methods ranged from 80.71 to 109.51% and 82.31 to 109.84%, respectively. The LOD of UV, GC–MS, and HPLC is 4, 20, and 1 ppm, respectively. The retention time of sulfur was 13.77 (HPLC), 2.89 (ultra high performance liquid chromatography), and 12.715 + 21.524 min (GC–MS). The method was successfully utilized for estimating sulfur in natural samples such as water from a sulfur hot spring and wastewater. The method has been validated by following the method recommended by the American Society for Testing and Materials. The HPLC method emerged as the best analytical method for the estimation of elemental sulfur.     

密圈圆柱形螺旋弹簧K值的精确计算

本文对密圈圆柱形螺旋弹簧应力公式中K值的三种形式的计算方法进行了推导和详细的讨论。从而在密圈圆柱形螺旋弹簧设计中能够恰当选用K值。     

非线性弹簧支承悬臂转子系统的动力仿真分析

基于非线性钢缆弹簧双线性迟滞模型描述方法，采用仿真分析，对非线性钢缆弹簧支承悬臂转子系统各主要参数与其动力性能的关系进行了研究，得出了其动力性能随系统参数变化的规律，为非线性钢缆弹簧支承立式冲击破碎机设计提供了理论依据。所得出的规律亦可供设计其它非线性钢缆弹簧支承转子系统及有关非线性转子系统时参考。     

Radon as a tracer for helium exploration in geothermal areas

High heat flow and weak structural features in geothermal areas allow easy passage for release of subsurface gases to the atmosphere. In particular, radon and helium are constantly transported from the earth's interior and vented out through exhalation points in permeable fault zones. At some places unusually large concentrations of helium may be encountered in soil airs. The possibility of trapping the released helium for bulk use has recently emerged. Because of its highly dispersive nature, helium is a difficult gas to detect during field explorations. Radon monitoring is thus taken up to locate structurally weak zones that allow helium permeation. The technique was recently adopted to determine high helium exhalation points in the Birbhum–Santhal Paragana geothermal area.     

一端带刚性质量的变截面梁的振动问题

一端带有刚性质量的变截面悬臂梁的振动问题,应用于塔式建筑结构。借助于Bessel函数,给出了振动系统的频率方程,并在一些参数值变化的情况下,给出了若干组前三阶频率值。得到的所有基频与已有文献中的结果完全一致,并能算出系统的任意阶频率。