摘要：Piezoelectric ceramic based high-temperature acoustic emission(AE)sensor is required urgently in the structural health monitoring of high-temperature *** this research,a series of 0.45(BiSc_(x)O_(3)-BiFe_(1-x)O_(3))-0.48PbTiO_(3)-0.07BaTiO_(3)(BSc_(x)Fe_(1-x)-PT-BT,n(Sc)/n(Fe)=0.4/0.6-0.6/0.4)ceramics with both high Curie temperature and large piezoelectric constant were *** structure and electrical properties of BSc_(x)Fe_(1-x)-PT-BT ceramics as a function of n(Sc)/n(Fe)have been systematically *** the ceramics possess a perovskite structure,and the phase approaches from the rhombohedral toward the tetragonal phase with the decrease of n(Sc)/n(Fe).The BSc_(0.5)Fe_(0.5)-PT-BT and BSc_(0.5)Fe_(0.5)-PT-BT piezoelectric ceramics exhibit good piezoelectricity(d_(33)=250-281 pC/N),high Curie temperature(T_(C)=430-450℃)and excellent temperature *** improvements are greatly attributed to the balance between rhombohedral and tetragonal phase near morphotropic phase boundary with dense microstructure of *** sensor based BSc_(0.5)Fe_(0.5)-PT-BT piezoelectric ceramic was designed,prepared and *** high-temperature stability of AE sensor was characterized through pencil-lead breaking with in situ high-temperature *** noise of AE sensor is less than 40 dB,and the acoustic signal is up to 90 dB at 200℃.As a result,AE sensors based on BSc_(x)Fe_(1-x)-PT-BT piezoelectric ceramics are expected to be applied into the structural health monitoring of high temperature fields.

摘要：目的:优选苦参生物碱的超声提取工艺。方法:以苦参中提取出苦参生物碱的百分含量为评价指标,以苦参碱和氧化苦参碱为对照品,采用高效液相色谱法测定超声法提取苦参中苦参碱和氧化苦参碱的含量。通过L9(34)正交试验,对影响超声法提取苦参中苦参碱和氧化苦参碱效果的四个因素(提取温度、提取时间、提取频率、提取次数)进行优选。结果:苦参药材粗粉在提取温度50℃、提取时间32min、超声频率35KHz、提取1次即可达到最佳提取效果。结论:本实验为优化苦参中苦参生物碱的超声提取工艺提供了参考依据。

摘要：城市空间形态与城市热环境的空间分异研究是城市生态环境、城市规划领域重要的研究议题。本研究以北京城区为例,基于Landsat数据,选取二、三维空间形态变量,探讨了局地气候分区(LCZ)视角下研究区四季的地表温度及城市热岛强度(UHII)变化与时空差异,并进一步分析城市空间形态变量对地表热环境的驱动机制。结果表明:1)研究区内建筑LCZ类型以密集中层LCZ 2和密集低层LCZ 3为主,自然LCZ类型以树林LCZ A/B为主,高密度建筑具有较高的热岛强度,且随着建筑高度增加地表温度降低,绿地和水体覆盖较多的区域热岛效应相对较弱,不同LCZ类型的热岛效应强度存在显著差异,夏季最为显著;2)从不同季节热环境空间分布来看,研究区在春夏两季表现为以热岛区为主,且夏季热岛强度和广度最高,UHII在5℃<UHII≤7℃的面积占比最大(26.34%),秋冬两季表现为以中温区为主;3)北京城区大部分街区整体的景观异质性和破碎度较低,景观形状较规则,中心城区容积率、建筑体积与建筑高度普遍较高,天空开阔度较小。通过对典型LCZ类型的热环境归因分析,结果表明,不同LCZ需要采用不同的优化策略,如LCZ 9(零散建筑)的关键影响因子只有BSF,LCZ 2(密集中层建筑)存在多个关键影响因子,需要协同多因子来优化城市热环境。研究结果能够为城市规划设计提供参考,助力于城市的可持续健康发展。

摘要：In order to speed up and simplify the design of the quadrotor unmanned aerial vehicle(UAV)and carry out experimental simulation and verification of relevant control algorithms,this paper analyzed the system dynamics model of the mechanical structure and flight principle of the quadrotor aircraft,and used the Newton-Euler method to derive the non-linear dynamic *** at improving the modeling accuracy and system integrity of the quadrotor,the physical system modeling was combined with the CAD software and the Matlab/Simscape *** three-dimensional quadrotor solid model built by CAD software was imported into the Simscape simulation platform to construct the body and power system model of the *** on this,the control algorithm designed by Simulink was added to the simulation platform to facilitate the experiment verification and parameter *** simulation results show that the designed aircraft can achieve hover and tracking well and meet the control performance requirements of the system.

摘要：Deamination is a crucial step in the transformation of 6-cyclopropylamino guanosine prodrug to its active form. A convenient method using capillary electrophoresis （CE） without sample labeling was developed to analyze the deamination of a series of D-/L-6-cyclopropylamino guanosine analogs by mouse liver homogenate, mouse liver microsome, and adenosine deaminase （ADA）. A two-step process involving a 6-amino guanosine intermediate formed by oxidative N-dealkylation was demonstrated in the metabolism of 6-cyclopropylamino guanosine to 6-hydroxy guanosine. The results indicated that the transformation rates of different prodrugs to the active form varied greatly, which were closely correlated with the configuration of nucleosides and the structure of glycosyl groups. Most importantly, D-form analogs were metabolized much faster than their L-counterparts, thus clearly pointed out that compared to guanine, modification of glycosyl part might be a better choice for the development of L-Kuanosine analogs for the treatment of HIV,

摘要：为提高马蹄形隧道机械化施工水平,以蒙华铁路白城隧道项目为依托,研制马蹄形盾构机。其关键技术包括:提出低扰动多刀盘、多驱动协同开挖技术,推导小刀盘扭矩系数计算公式;研究马蹄形管片分块方式,设计1种多自由度变曲率管片拼装机,解决变曲率、大重量管片的拼装难题;研究双螺旋输送机联合出渣技术,基于Fluent仿真分析对开挖面进行流场仿真,通过压力监控及反馈实现双螺旋输送机土仓压力实时控制;设计梭式盾体结构,给出无铰接盾构机最小转弯半径计算方法,并提出相应的纠滚措施。研制的盾构机在施工过程中掘进性能良好,能满足安全、快速、环保施工的要求。针对出现的排渣不畅问题,提出利用高压水射流技术对渣土进行切割冲刷,在螺旋输送机上部设置2个推土器装置;而对出现的顶推力过大问题,则采取增大下部3个刀盘的直径等改造措施。改造后的马蹄形盾构机在蒙华铁路白城隧道的成功应用,使得马蹄形隧道使用盾构法施工成为现实。

摘要：本文提出了一种不依赖模块规格型号和换热器几何参数的热电制冷系统分析方法,设计了水冷式热电冷水机的基本结构,考虑了汤姆逊效应,应用了有限时间热力学理论,建立了新的热力学模型,研究了热源、冷源沿流动方向的温度变化,分析了不同冷却水温度、输入电流密度、模块填充系数和热电单元长度对装置制冷性能的影响。

摘要：为了研究导叶位置对双向竖井贯流泵水力性能与流态的影响,利用CFX14.5对6种导叶位置方案的双向竖井贯流泵在正向运转与反向运转时分别进行小流量工况(0.8Qdes)、设计流量工况与大流量工况(1.1Qdes)的定常计算,总计共36个工况。将数值模拟结果与泵装置外特性试验数据进行验证对比,并对计算结果进行水力性能与流态分析。研究结果表明:泵装置数值模拟结果与试验数据吻合度良好,最大相对误差小于5%。泵装置正向运转时,在小流量下,泵装置效率随导叶位置S增加而下降,S=40 mm时的导叶水力损失最大;但是在设计流量与大流量下,泵装置效率随导叶位置S增加而上升,S=100 mm时的导叶水力损失最小。泵装置反向运转时,导叶位置对泵装置水力性能与流态没有显著影响,综合考虑,选择导叶位置S=100 mm作为最终方案。

摘要：描述了同时考虑加工与装配作业的多产品综合作业调度问题,利用经典作业调度问题FT10的数据构造了一个问题例子,设计了基于产品结构信息的字符串直接解码方法.计算结果表明:设计的遗传算法是可行和有效的,得到的装配完工时间接近无限能力概念下得到的最小值,并且优于关键路径调度规则的结果.

摘要：介绍了紧凑型Tesla变压器的工作原理和功能特点,在此基础上对电压1.0 MV、重复频率100Hz的Tesla变压器和阻抗40Ω、宽度40 ns的脉冲形成线(PFL)进行了一体化结构设计。用Tesla变压器的两个同轴开环铁芯作为PFL的内外导体,将传统的形成线结合在Tesla变压器中,从而脉冲发生装置具备了体积小、效率高、性能稳定等特点。设计的紧凑型Tesla变压器在CHP01电子束加速器上实现了对600 pF的PFL单次充电电压达到1.3 MV、重复频率100 Hz、平均电压1.15 MV的技术指标,该变压器在其额定电压和频率下的连续运行时间达到5 s以上。