A mathematical model with experiments of single effect absorption heat pump using LiBr–H2O

A mathematical model of a single effect, LiBr–H₂O absorption heat pump operated at steady conditions is presented. This model took into consideration of crosscurrent flow of fluids for heat and mass exchangers, two-dimensional distribution of temperature and concentration fields, local values of heat and mass transfer coefficients, thermal parameter dependent physical properties of working fluids and operation limits due to the danger of the LiBr aqueous solution hydrates and crystallization. Improvements of the calculation method make this simulation much more convenient and efficient. An improved absorber experiment set-up and a complete absorption heat pump were built and tested for further study. It was found that the mass flux of vapor increased with the increase of absorber pressure, coolant flow rate, spray density of LiBr solution and decrease of coolant and input temperature of solution. And the vapor mass flux increased almost linearly with the increase of absorber pressure. Results derived from this model show agreement within 7% with experimental values.     

圆柱面桥梁支座消失模铸钢件缺陷预防

YZM系列圆柱面支座是一种新型铁路桥梁钢支座,采用消失模铸造工艺生产铁路桥梁钢支座有许多优点.通过实验分析描述了各种缺陷形成机理,研究了模样材料性质、浇注温度、涂料、真空负压等主要因素对消失模铸钢件缺陷的影响,并提出了防止缺陷的一些措施.     

预应力钢绞线张拉数据偏差分析及对策

针对案例中预应力钢绞线张拉数据的偏差问题,通过详尽的原因分析,计算出预应力损失并复测钢绞线的有效预应力,肯定了该批预应力构件的合理性和使用性能,避免了大量的经济损失和工期损失,为解决类似工程问题提供了科学参考。     

感应电机转子故障特征在交直交变频器中的传播

为研究感应电机转子故障特征在交直交变频器中的传播规律,在感应电机由交直交变频器驱动的系统中,利用逆变器和整流器的开关函数,对感应电机发生转子断条故障时的逆变器直流侧电流和整流器交流侧电流进行了解析分析,发现了对应的故障特征频率分量。分别在感应电机转子一根断条和转子两根断条的情况进行试验,试验结果也证明了理论分析的正确性,这为从变频器的整流器交流侧诊断感应电机转子故障提供了理论依据。     

地下水年度用水计划编制技术探讨

编制和实施地下水年度用水计划,是实现地下水精细化管理的基础。分析探讨了编制地下水年度用水计划的原则、程序、年度计划开采量的确定方法以及发生特殊干旱和突发事件等情况时,对地下水年度用水计划进行调整的原则要求。地下水年度用水计划的编制应充分考虑区域地下水开发利用总量控制指标、预测的来年水资源状况、上年度的地下水用水状况以及经济社会发展需求等因素。     

锅炉一级过热器管壁磨损原因分析

国华准格尔发电有限责任公司1号、2号炉一级过热管排与省煤器悬吊管接触部位发生磨损，并最终导致一级过热器管排泄漏。根据磨损部位特征，确定飞灰是导致磨损的主要原因。通过方案论证，在一级过热器管排上方加装防磨阻流板，阻止烟气通流，有效解决了一级过热器管排磨损泄漏的问题。     

Enhancement of top emission for organic light-emitting diode via scattering surface plasmons by nano-aggregated outcoupling layer

A stable self nano-aggregated bathocuproine film was fabricated and introduced atop of a conventional organic light emitting diode for enhancing top emission. It leads to a 2.7–2.1-fold enhancement on top emission at applied voltage from 4 to 9 V which is much larger than the 1.5–1.3-fold enhancement for a device overlaid with an amorphous bathocuproine film. The more effective outcoupling of this method probably arises from surface plasmon modes being scattered by only the nanostructured surface, and thus without phase cancellation, at the bathocuproine/air boundary. Moreover, this method nearly preserves the original electroluminescent spectra and has no damage on electrical properties.     

Synthesis and characterization of La2Ti2O7 employed for photocatalytic degradation of reactive red 22 dyestuff in aqueous solution

Perovskite structured La₂Ti₂O₇ catalyst prepared by polymerized complex method was characterized and examined the photocatalytic activity by decomposing an azo dyestuff, Reactive Red 22, in aqueous solutions under UV irradiation. La₂Ti₂O₇ powders prepared by polymerized complex method exhibit higher surface areas, better homogeneity and are more sensitive to solution than those prepared by solid-state method. The first derivatives of UV–vis DRS patterns confirmed the complete crystallization of La₂Ti₂O₇ sintered at temperatures higher than 900 °C. The effects of sintering temperature of catalyst and solution pH of photocatalytic reaction were studied. The photocatalytic decomposition of Reactive Red 22 per unit surface area was found to be higher for experiments using La₂Ti₂O₇ than using TiO₂. However, the electron–hole recombination was found to be more obvious for La₂Ti₂O₇ than for TiO₂ because the network of metal cations constructed within La₂Ti₂O₇ enhances the mobility of photogenerated electrons and holes.     

国家标准《消失模铸件质量评定方法》解读

国家标准GB/T 26658-2011《消失模铸件品质评定方法》已于2011年6月发布,定于2012年6月1日实施.为了推广贯彻这项标准,提高消失模铸件品质,对标准制定的各项技术指标和我国消失模铸造生产实际品质控制情况进行简要评述,以此对标准中的指标进行说明,便于消失模铸造企业贯彻执行,对消失模铸件品质进行控制.     

Stability of first and high order iterative learning control with data dropouts

This paper presents a stability analysis of the iterative learning control (ILC) problem for discrete-time systems when the plants are subject to output measurement data dropouts. It is assumed that data dropout occurs during the data transfers from the plant to the ILC controller, resulting in what is called intermittent ILC. Using the super-vector approach for ILC, the expectation of output error is used to develop conditions for stability of the first order ILC and high order ILC processes. Through the theoretical analysis, it is shown that the convergence of the intermittent ILC is guaranteed although some measurements are missing. The analysis is also supported by numerical examples.