近红外快速水份检测技术的应用

近红外检测技术是目前发展最快和最具有前景的分析技术之一,简要介绍了近红外检测技术的发展、优点和原理.利用该技术设计了豆类产品的水份检测仪器.并对近红外技术在水果、蔬菜、奶制品、制药和化工等方面的应用前景做了展望.     

6S现场管理方法在计量检测实验室中的应用

6S现场管理的方法已经在多个领域得以运用并取得较好的效果。结合计量检测实验室的特点,从整理、整顿、清扫、清洁、素养、安全6各方面讨论了6S现场管理在计量检测实验室中的应用。该管理模式可以提高工作效率,降低物品遗失率,减少寻找物品的时间等,提高计量检测质量。     

Assessing contaminated hydrogen peroxide for safe storage and transportation using the FTAI

Hydrogen peroxide is a very versatile oxidizing agent, and it is also environmentally compatible considering that the products of its exothermic decomposition are oxygen and water.When kept in a clean temperature-controlled environment, the self-reaction (decomposition) rate is extremely low. However, it is well known that even a small amount of contamination will dramatically increase the reaction rate. This paper describes the use of the fast thermal activity interpreter (FTAI) instrument to examine the chemical reactivity of commercially available 50% hydrogen peroxide at two different temperatures (30 and 40°C) both with and without contamination. The results show that at 30°C a small amount of rust (330 ppm) increases the reaction rate of 50% hydrogen peroxide by a factor of 50. When the temperature is increased to 40°C, the reaction rate is further increased by almost a factor of four. The implication for reactivity management is that at this contamination level most practical vessel sizes would require emergency venting capability. An evaluation was then performed to determine the emergency venting requirement for the safe transportation or storage of the contaminated hydrogen peroxide. It was determined that for quantities of the material less than 5 gallons, conventional breather vents would be sufficient to accommodate the gas evolved. However, for larger quantities, a safety relief device would be needed. For example, for a 400-gallon tote bin at 40°C the required minimum vent area is estimated to be 4.3 in², corresponding to a minimum vent diameter of 2.3 inches.     

Lifetime prediction of a blue PE100 water pipe

The traditional method to assess the lifetime of plastic pipes is based on hydrostatic pressure testing. A complementary approach has been conducted to monitor the depletion of antioxidants and initiation of thermo-oxidative degradation on a PE100 blue water pipe that had been exposed to hydrostatic pressure in water at low test temperatures (maximum 80 °C).Depletion of antioxidants was monitored using OIT testing and initiation of thermo-oxidative degradation was assessed by iodometric detection of hydroperoxides. An empirical model based on the Arrhenius fit of the data was developed to extrapolate the lifetime of the PE100 pipe material at various service temperatures (10-25 °C). Associated activation energies, E_a, were determined and appeared to be in line with the values obtained from experiments carried out at low test temperatures. The combination of pressure testing and chemical analyses proved to be a very powerful tool to extrapolate the lifetime of plastic pipes.     

膨胀管残余应力测试

膨胀管残余应力是影响膨胀管抗外挤、内压强度的重要因素之一。确定膨胀管的残余应力,测试方法至关重要。在常用测试方法中,机械测量法中的盲孔法体现出测试的优越性。应用盲孔法测试J55、K55两种规格膨胀管的残余应力,并根据实际测试的应力水平和实验误差,采用应变释放系数分级法对试验结果进行修正,以提高测试结果的精度。实验结果表明,膨胀管膨胀后存在环向、轴向的残余应力,且外表面总是压残余应力。将实验结果与仿真结果对比,误差满足工程要求,说明盲孔法测试膨胀管残余应力方便、快捷、准确、有效。     

厚壁管道周向导波检测技术实验研究

厚壁管道是火电机组四大管道系统的核心部件,将超声导波技术应用于厚壁管道的无损检测显得十分重要.首先确定厚壁管道检测的激励方式,优化选取适合厚壁管道检测的0.5MHz探头和楔形块角度为60°的斜探头组合.通过改变斜探头与外壁轴向缺陷之间周向距离,在一定范围内仍可检测到缺陷回波,且接收到的周向回波幅值变化不大,表明周向导波...     

An experimental investigation into non-linear wave loading on horizontal axis tidal turbines

Tidal turbines are subject to large hydrodynamic loads from combinations of currents and waves, which contribute significantly to fatigue, extreme loading and power flow requirements. Physical model testing enables these loads and power fluctuations to be assessed and understood in a controlled and repeatable environment. In this work, a 1:15 scale tidal turbine model is utilised to further the fundamental understanding of the influence of waves on tidal turbines. A wide range of regular waves are generated in both following-current and opposing-current conditions. Wave frequencies range from 0.31 Hz to 0.55 Hz & wave heights from 0.025 m to 0.37 m in a fixed 0.81 m/s current velocity. Waves are selected and programmed specifically to facilitate frequency domain analysis, and techniques are employed to isolate the effect of non-linear waves on turbine power and thrust.Results demonstrate that wave action induces large variations in turbine power and thrust compared to current only conditions. For the range of conditions tested, peak values of thrust and power exceed current-only values by between 7%–65% and 13%–160% respectively. These wave-induced fluctuations are shown to increase with wave amplitude and decrease with wave frequency. Following wave conditions exhibit greater variations than opposing for waves with the same wave height and frequency due to the lower associated wavenumbers.A model is developed and presented to aid the understanding of the high-order harmonic response of the turbine to waves, which is further demonstrated using steady state coefficients under assumptions of pseudo-stationarity. This approach is proven to be effective at estimating wave-induced power and thrust fluctuations for the combinations of waves, currents and turbine state tested. The outcome of which shows promise as a rapid design tool that can evaluate the effect of site-specific wave–current conditions on turbine performance.     

无条件稳定数值积分方法在拟动力实验中的应用研究

用无条件稳定的隐式α－方法代替目前的条件稳定的显式方法，通过数值迭代控制方法实现了拟动力实验．在此基础上进一步应用子结构技术，解决了刚度大、自由度较多结构采用传统的条件稳定数值积分方法进行拟动力实验的问题．应用不同数值积分方法进行的三层模型结构的实验结果表明，无条件稳定的数值积分方法的实验精度优于条件稳定的数值积分方法的精度．文中还就实验误差的控制补偿问题进行了讨论，提出了采用瞬时割线刚度进行补偿的方法     

航天结构热力力学的任务和应用

本文给出航天结构热力力学的应用背景和工作任务．首先讨论它的先决条件:载荷谱和材料特征．其次介绍一些典型的热力力学结构:再入热防护系统,轨道空间结构,以及碳纤维增强复合材料板件．然后,介绍热力力学的工作内容:热分析,经典结构分析,热损伤力学,以及热力力学耦合和结构试验．最后为简单展望．      

基于正极性或-符合展开的易测性网络

为提高数字电路的可测性,提出了可实现任意逻辑函数的正极性或-符合网络的易测性实现,并给出了测试网络中所有单固定故障的通用测试集．该实现基于逻辑函数的正极性或-符合展开,网络的同或部分分别采用了串联和树形结构．为提高可测性,同或串的实现结构只需增加1个控制端及1个观察端,同或树的实现结构只需增加3个控制端及1个观察端．对于1个n变量的逻辑函数,两种实现结构下通用测试集的基数分别为（n＋4）和（n＋5）．这样短的通用测试集非常适合用内建自测试实现,从而有效地缩短测试时间．