一段炉转化管热带现象原因分析及处理

针对转化管出现的热带(超温)现象,结合一段炉的运行数据,从转化管改薄壁管、催化剂活性降低、催化剂结炭等方面进行分析与探讨,并采取一系列的操作优化及烧炭处理,避免了装置的停车,保证了系统的长周期稳定运行。     

建设工程合同履行过程中的索赔

在工程合同履行中 ,常常遇到“索赔事件”.这是一种经常补偿行为 ,而不是惩罚 ,是工程承包中经常发生的正常现象 .“索赔”的健康开展对于培养和发展建设市场 ,促进建筑业的发展 ,提高效益有重要作用 .尽管产生“索赔”的原因很多 ,但处理索赔均应遵循 :“以合同为依据、重事实、重证据、加强前瞻性、主动控制”的原则     

自防水混凝土抗渗性能的探讨

从混凝土的组成、混凝土的孔隙和混凝土的离析现象等方面分析了混凝土的渗水原因,提出了改进混凝土抗渗性能的措施,指出混凝土自防水工程施工简便、抗渗性和耐久性优良,与采用表面防水层相比具有良好的技术经济效果。     

Further study on counter-intuitive response of single-degree-of-freedom structures

An energy method was proposed in Li et al. (2008), Int J Impact Eng 35(8):784-94 to determine the counter-intuitive region of the breathing mode response of plane-stress rings, which has different mechanism from the counter-intuitive phenomena observed in beams and plates. This paper extended the energy method for plane-stress rings to plane-strain rings and spherical shells for the determination of the counter-intuitive regions of the breathing mode response. Numerical simulations are conducted to support the predictions based on the energy method.     

Mechanism of simultaneous tripping of ground directional relays in a 6.6‐kV distribution system

In Kyushu Electric Power's 6.6‐kV distribution system, after a single‐phase ground fault occurred in the circuit of a distribution line, we experienced a phenomenon in which the analogue ground directional relays of the other circuits linked to the same bank were simultaneously tripped. In this paper, focus is placed on the mechanism and possibility of simultaneous tripping of ground directional relays. This mechanism was examined in an experiment carried out using an analogue simulator. The results of the test revealed that such simultaneous tripping was attributable to the neutral instability phenomenon of grounding potential transformers installed in an isolated neutral system. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(2): 23–30, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20919     

高校大学生逃课现象调查与研究

针对目前大学生逃课情况较为严重的现状,本文通过对某高校大学生的调查,分析引发大学生逃课的原因,并有针对性地提出一些建议来减少大学生逃课,从而达到提高高等教育教学质量的目的。     

ASA树脂制件的分层原因

通过宏观分析、红外光谱分析、热分析和高压毛细管流变分析对ASA树脂制件分层原因进行了分析。结果表明:发生分层的ASA树脂制件混入了PP树脂,两者流动性和结晶性的差异导致了制件的分层。     

The impact of the physical model selection and rock mass stratification on the results of numerical calculations of the state of rock mass deformation around the roadways

At present, the basic methods used for designing and evaluating the stability of mine workings are numerical models. The finite element method is the most popular method for engineering purposes. However successful calculations depend not only on the proper selection of geomechanical properties of rocks but mainly on the proper selection of a physical model describing the behavior of the rock mass and a selection of the correct failure criterion. The best way of verifying results of the calculations is to carry out investigation in the field, then.This article shows how the choice of a numerical model affects the size of the calculated damage zone around the working. To that end, numerical calculations considering elastic and elastic–plastic models were performed for six roadways. The rock mass was further differentiated in terms of its stratification and approach to mechanical properties of the rock mass. The results of these calculations were compared with measurements of mine convergence and the damage zone range in the roof. Such measurements were carried out at hard coal mine roadways.     

具有振动支点的弹簧摆的共振分析

研究了支点沿垂直方向谐振的弹簧摆的运动，其运动由两个相互耦合的常微分方程描述。用多尺度法分析了当激励濒率Ω≈ω１，ω２时的共振行为，并分析了当ω１／ω２≈２．０时的内共振响应，发现了存在饱和现象，找到了参数共振时的不稳定区域。     

液化天然气(LNG)储存容器中的分层与翻滚

针对储罐中液化天然气（LNG）在温度差和密度差下的分层行为，建立LNG分层的异重流模型。并利用Lorenz方程描述异重流下层的热对流状态。采用耦合映象格子模型求解Lorenz方程，并引入对流强度量判断系统分层涡旋的产生和发展。对系统的数值模拟研究，确定了系统处于独立循环、分层翻滚及对流循环状态时对应的瑞利数Ra临界值。证明了系统在密度差趋于相等时，分界面被打破，LNG大量蒸发出现分层翻滚现象；并得到了系统随主要控制参数Ra的发展过程及分层翻滚发生的时间、高峰蒸发量等。计算表明：对于给定的密度差和温度差，底层的LNG厚度越大，则出现翻滚现象的时间越迟；底层厚度越大，高峰蒸发速度也越大，较易引发储罐超压；对于给定温度差，底层LNG密度较大时，出现翻滚的时间会相对提前。