轴流压气机旋转失速建模与检测II: 基于北航低速压气机试验台的实验研究

轴流压气机旋转失速和喘振的提前检测对于提高压气机工作效率和稳定性具有重要的意义.本文以北京航空航天大学航空发动机重点实验室的低速轴流压气机实验台为研究对象,基于确定学习理论及动态模式识别方法,开展旋转失速初始扰动近似准确建模和快速检测研究.首先,在压气机机匣壁面周向布置多个动态压力传感器,获取压气机失速前和失速先兆的动态压力信号,基于确定学习理论对旋转失速初始扰动的内部系统动态进行建模;其次,基于以上建模,利用微小振动故障检测方法实现对旋转失速的离线和在线提前检测.实验结果表明,本文所提方法能够在不同转速情况下,提前0.3 s~1 s实现对旋转失速的实时在线检测.     

Preparation and electrical conductivity of polyethers/WS2 layered nanocomposites

Utilizing the solvothermal synthesis technique, lithium intercalated tungsten disulfide Li_xWS₂ with x > 1 was obtained, which was allowed to react with water to the formation of single-molecule-layer suspension of tungsten disulfide. The layered nanocomposites PEG, PEO/WS₂, intercalating poly(ethylene glycol) (PEG, MW ≈ 1 × 10³, 6 × 10³, 1 × 10⁴) and poly(ethylene oxide) (PEO, MW ≈ 3 × 10⁵) into the tungsten disulfide host galleries, were prepared using the improved exfoliation-adsorption technique. It was revealed that the intercalated polymers within the host galleries are in a double-layer arrangement with an interlayer expansion of about 9 Å. Despite high conductivity of the host material, those of the PEG, PEO/WS₂ nanocomposites were found to be high in the order of 1 × 10⁻² to 10⁻³ S cm⁻¹ at ambient temperature, resulted from the guest-host charge transfers.     

Synergistic effects of doped Fe3+ and deposited Au on improving the photocatalytic activity of TiO2

Fe³⁺ doped together with Au deposited TiO₂ (Au/Fe³⁺–TiO₂) was successfully prepared, which shows excellent photocatalytic activity for degradation of methyl orange (MO) under both UV and visible light (λ > 420 nm) illumination. Fe³⁺ has been confirmed by EPR to substitute for Ti⁴⁺ in the TiO₂ lattice, and Au exists as Au⁰ on the surface of the photocatalyst indicated by the results of XRD. Fe³⁺ and Au have synergistic effects on improving the photocatalytic activity of TiO₂. A proposed mechanism concerning the synergistic effects is discussed to explain the improvement of the photocatalytic activities.     

2,6-二(三氟甲基)吡啶的合成研究

以2,6-二氯吡啶为原料,制得2,6-二溴吡啶(收率79%)或2,6-二碘吡啶(收率56%),再分别与三氟乙酸钾反应,均可得标题化合物,收率28%~53%。该合成路线的优点是原料易得,反应条件温和,收率较高。     

水热离子交换时间对铯离子改型白榴石的影响

为实现对白榴石热膨胀系数的有效调控,利用铯离子对白榴石粉体进行改型。将白榴石粉体在浓度为0.3 mol/L的硫酸铯溶液中进行水热离子交换处理。利用X射线衍射仪（XRD）和扫描电子显微镜（SEM）对180 ℃下不同离子交换时间得到样品的物相和形貌进行了分析和观察。结果表明:铯离子进入白榴石晶格后,使部分白榴石转变生成了铯榴石,并且随着保温时间的延长,产物铯榴石晶体会逐渐由四方晶系过渡为立方晶系。当保温时间超过10 h时,两相间内应力增加会导致铯榴石从白榴石颗粒表面脱落,所以保温时间应该控制在2~10 h。利用JMA方程对合成铯榴石生长动力学过程进行拟合分析,从Avrami指数n小于0.5可知,整个反应主要由扩散控制。     

Discriminative multi-task objects tracking with active feature selection and drift correction

In this paper, we propose a discriminative multi-task objects tracking method with active feature selection and drift correction. The developed method formulates object tracking in a particle filter framework as multi-Task discriminative tracking. As opposed to generative methods that handle particles separately, the proposed method learns the representation of all the particles jointly and the corresponding coefficients are similar. The tracking algorithm starts from the active feature selection scheme, which adaptively chooses suitable number of discriminative features from the tracked target and background in the dynamic environment. Based on the selected feature space, the discriminative dictionary is constructed and updated dynamically. Only a few of them are used to represent all the particles at each frame. In other words, all the particles share the same dictionary templates and their representations are obtained jointly by discriminative multi-task learning. The particle that has the highest similarity with the dictionary templates is selected as the next tracked target state. This jointly sparsity and discriminative learning can exploit the relationship between particles and improve tracking performance. To alleviate the visual drift problem encountered in object tracking, a two-stage particle filtering algorithm is proposed to complete drift correction and exploit both the ground truth information of the first frame and observations obtained online from the current frame. Experimental evaluations on challenging sequences demonstrate the effectiveness, accuracy and robustness of the proposed tracker in comparison with state-of-the-art algorithms.     

BP网络在加热炉效率评定中的应用

以工艺管式炉有关数据为例，将BP网络有效应用于数据的压缩存储和快速计算，为加热炉效率评定软件提供了BP网络模型。利用MATLAB软件实现了BP网络的训练及仿真分析，并讨论了应用过程中参数的选择以及训练数据的特点对网络训练产生的影响。     

乙炔吸收系统倒开车实现装置产品快速合格

中国石油吉林石化公司聚乙烯厂700kt/a乙烯装置老区采用溶剂吸收技术脱出乙炔精制乙烯工艺。多年来,乙炔吸收塔塔顶回流泵开车初期不上量问题一直制约着装置开车进度。经过摸索,技术人员尝试对开车流程进行调整,攻克了难题。文中对该装置具体的调整措施进行了阐述。     

发泡鞋底材料研究现状及发展趋势

综述了发泡鞋底材料的研究现状，并由此总结出发泡鞋底材料的发展趋势。     

脱硫石膏粉煤灰胶结材水化硬化机理及耐水性研究

以火电厂的两种废渣即脱硫石膏和粉煤灰为主要原料制得的胶结材，其强度明显高于普通石膏制品，软化系数大于０．８５。采用水化热测定、ＸＲＤ和ｐＨ值测定及ＳＥＭ／ＥＤＸＡ分析，并结合宏观试验结果，分析了这种胶结材的水化硬化机理和微结构特点，并对其耐水性提高的原因进行了讨论。