Application of electrical capacitance tomography to the void fraction measurement of two-phase flow

Based on the electrical capacitance tomography technique, a new method for the void fraction measurement of two-phase flow is proposed. A 12-electrode void fraction measurement system is established. A mathematical model of image reconstruction of electrical capacitance tomography is developed. To obtain the quantitative information of two-phase flow, combining the Tikhonov regularization principle and the algebraic reconstruction technique algorithm, a new image reconstruction algorithm is presented. The experimental results show that the accuracy of void fraction measurement is satisfactory. The proposed method is suitable for the void fraction measurement of many kinds of two-phase flow.     

用激光感应荧光法测量钇原子束中的原子速度分布

本文用激光感应荧光法测量了钇原子束的速度分布曲线。其最可几速度为820m/s,速度分布半宽度为510m/s。由等熵关系,估计此时钇原子源的温度为1587K。     

阻抗匹配平衡变压器的电量变换和运行计算

阻抗匹配平衡变压器,是适应我国电气化铁道的发展需要,已完成研制并投入运行的新型平衡变压器。它在变压的同时还要换相,故其电磁结构和运行性能有不同特点。为了便于推广应用,本文对其在牵引供电系统中应用感兴趣的几个问题,分别加以讨论。在论述一、二次的电量变换关系后,进而阐明相关的运行计算。这不仅是解决本变压器的运行问题,对加深三相变两相诸多概念的理解也有好处。     

电容层析成像系统整体性能的改善

采用代数重建算法处理由电容层析成像系统所采集的投影数据可以获得较高质量的图像,介其耗时较多。本文着重提出一种准则并以此优化迭代过程中投影的选取顺序,以提高代数重建算法的收敛速度,从而改善成像系统的整体性能。     

Electrospinning Preparation and Drug‐Delivery Properties of an Up‐conversion Luminescent Porous NaYF4:Yb3+, Er3+@Silica Fiber Nanocomposite

Up‐conversion (UC) luminescent porous silica fibers decorated with NaYF₄:Yb³⁺, Er³⁺ nanocrystals (NCs) (denoted as NaYF₄:Yb³⁺, Er³⁺@silica fiber) are prepared by the electrospinning process using cationic surfactant P123 as a template. Monodisperse and hydrophobic oleic acid capped β‐NaYF₄: Yb³⁺, Er³⁺ NCs are prepared by thermal decomposition methodology. Then, these NCs are transferred into aqueous solution by employing cetyltrimethylammonium bromide (CTAB) as secondary surfactant. The water‐dispersible β‐NaYF₄:Yb³⁺, Er³⁺ NCs are dispersed into precursor electrospinning solution containing P123 and tetraethyl orthosilicate (TEOS), followed by preparation of precursor fibers via electrospinning. Finally, porous α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber nanocomposites are obtained after annealing the precursor fibers containing β‐NaYF₄:Yb³⁺, Er³⁺ at 550 °C. The as‐prepared α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber possesses porous structure and UC luminescence properties simultaneously. Furthermore, the obtained nanocomposites can be used as a drug delivery host carrier and drug storage/release properties are investigated, using ibuprofen (IBU) as a model drug. The results indicate that the IBU–loaded α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber nanocomposites show UC emission of Er³⁺ under 980 nm NIR laser excitation and a controlled release property for IBU. Meanwhile, the UC emission intensity of IBU–α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber system varies with the released amount of IBU.     

Balancing Economic Development and the Preservation of Agricultural Land: An Evaluation of Shanghai's Municipal Land Use Plan

The megacity of Shanghai faces enormous planning challenges, particularly controlling rapid urban growth and preserving some of the world's most fertile agricultural land. Almost two-thirds of Shanghai's territory is classified as agricultural land. Maintaining this high ratio of agricultural land to total land area and, at the same time, accommodating a large and rapidly increasing urban population represents an immense and complex planning challenge. Shanghai has recently adopted a Municipal Land Use Plan to address some of these planning challenges. This article provides a review, analysis and critique of Shanghai's Municipal Land Use Plan. From a review of the relevant literature, this article develops a framework to evaluate Shanghai's plan. This framework provides a qualitative assessment of the strengths and weaknesses of the SMLUP's overall goal of preserving arable land and fostering urban-economic development.

     

塔里木盆地跃满地区超深油藏成藏地质条件与演化过程

塔里木盆地台盆区深层海相碳酸盐岩在7 000 m以深持续发现大型油气聚集,但由于其复杂的地质结构与演化特征,仍需进一步加强油气成藏研究。位于塔北隆起西南部围斜的跃满地区发现了埋深在7 100~7 600 m之间的超深油藏,通过对该油藏的地质—地球化学综合分析,厘定了超深油藏成藏的有利条件：深大断裂一方面控制了岩溶作用的发生,导致一间房组大规模层间岩溶的发育与断溶体圈闭的形成、并与上覆吐木休克组和桑塔木组有效盖层组成了有利的储盖组合;另一方面作为流体运移的优势通道,为来自寒武系—奥陶系烃源的油气运移提供了便利条件;油气成藏后在低地温梯度和晚期快速深埋条件下,由于时间与温度的补偿效应不足,原油未发生裂解,以单一油相保存。跃满地区超深油藏成藏演化过程揭示了深层仍具有巨大的液态石油勘探潜力,勘探目标以具有串珠状强反射的断溶体油气藏为主。     

连续单频激光的腔外调频及其在光谱测量中的应用

研制了一台通光孔径为２ｍｍ的ＬｉＴａＯ３射频电光调制器，调制频率为９５ＭＨｚ。获得十个边频分量，并对调频结果作了分析。应用此器件所产生的调频激光束测得２３８Ｕ和Ｌａ的荧光谱，对比和分析了单频激光和调频激光荧光谱的差别，获得了明显的谱线增宽及增强效应。     

沿海城市防洪减灾系统的总体功能设计

阐述沿海城市防洪减灾的重要性，提出沿海城市防洪减灾的一般措施及沿海城市防洪减灾系统的基本任务；按照沿海城市防洪减灾系统的设计目的和原则，进行沿海城市防洪减灾系统的总体功能设计，认为该防洪减灾系统的主要功能组成部分包括ＧＩＳ，信息咨询，水文，气象信息自动测报，接收与显示，洪水预报，警报与通讯，水库，排涝泵站和滞洪区调度，立法，执法与规划，应急，水土保持等８个子系统；