Textural and microstructural developments during fabrication of Zr-2.5Nb pressure tubes

Zr-2.5wt%Nb pressure tubes, as used in the Indian pressurized heavy water reactors (PHWR), are fabricated through a combination of hot extrusion followed by two stages of cold pilgering and annealing. The present study makes an effort to systematically characterize the textural changes during the fabrication stages. The starting single-phase hcp martensitic structure was textured to start with and it also went through strong texture developments during hot extrusion. First and especially the second pilgering modified the texture. Such modifications were related to local discontinuity of the softer second phase, as an apparent continuity restricted lattice rotation in the primary hcp phase. Annealing caused discontinuity or spherodization of the bcc phase, but did not create recrystallization in the hcp matrix. The combination of two pilgering plus annealing operations, though the latter did not cause noticeable texture changes, however, reverted the final texture close to the parent hot-extruded texture.     

探析热电制冷

本文指出热电制冷是2l世纪极有发展前景的制冷新技术，但目前发展水平还不够高。由于制冷系数低、性能价格比较低及对电源要求较高等因素，目前发展受到了制约。新材料、新工艺、新技术及新电源的突破发展，是热电制冷进入一般工业和家庭生活的前提。     

Bioactivity and cytocompatibility of plasma-sprayed titania coating treated by sulfuric acid treatment

Titania coatings were fabricated on titanium alloy substrate using atmospheric plasma spraying technology, and treated by sulfuric acid (H₂SO₄) at room temperature for 24 h. The as-sprayed and acid-treated titania coatings were soaked in simulated body fluid (SBF) to investigate the formation of apatite on their surfaces. Human mesenchymal stem cells (MSCs) were used to evaluate the cytocompatibility of titania coatings. The results indicated that bone-like apatite was formed on the surfaces of acid-treated titania coatings after soaked in SBF for a period of time. The concentration of sulfuric acid had an effected on the bioactivities of titania coatings. The bioactivity of titania coating could not be improved by 0.01 M sulfuric acid treatment. The MSCs could attach, grow and proliferate well on the surface of titania coatings. The results showed that plasma-sprayed titania coating after acid treatment exhibited favorable bioactivity and cytocompatibility.     

Variability in pheromone composition and periodicity of pheromone titer in potato tuberworm moth,Phthorimaea operculella (Lepidoptera: Gelechiidae)

The ratios and quantities of the pheromone components, (E,Z)-4,7-tridecadien-1-yl acetate (diene) and (E,Z,Z)-4,7.10-tridecatrien-1-yl acetate (triene), in the glands of individual female potato tuberworm moths (Phthorimaea operculella) originating from the United States (California) and Japan (Nagoya) were analyzed by gas chromatography. Quantities of glandextracted pheromone components of Nagoya females fluctuated in a periodic fashion during the photoperiod. Maximal titers coincided with the onset of scotophase (and calling), then gradually declined to minimal levels soon after lights-on. The average daily pheromone quantities decreased significantly as females aged. Both populations exhibited considerable variation in the ratio of the two components. The proportions of triene in the blend ranged from 27% to 88% (triene –X = 56 ± 13% SD; CV = 23%) for California females and from 16% to 71% (42 ± 13%; CV = 31%) for Nagoya females. Nagoya females also stored significantly higher amounts of pheromone in their glands (8.6 ± 3.9 ng) than did California females (2.7 ± 1.4). The differences between the populations, while substantial, would probably not be sufficient to impart a barrier to panmixis, given the wide range of component ratios favored by the males.     

色散媒质中采用Z变换的ADI-FDTD方法

基于Z变换方法将ADI-FDTD推广应用于色散媒质,得到了二维情况下色散媒质中的迭代差分公式,同时给出了一种采用ⅡR滤波器结构来减少存储量的方法.本文方法适合于任意M阶色散媒质,最后,给出了一个算例,数据仿真结果表明,本文的算法与传统色散媒质中的FDTD相比,在计算结果吻合的情况下,存储量相当,计算效率却更高,时间步长仅仅由计算精度来决定.     

Eingangsportal; Änderung des äußeren Ansehens; baubewilligungspflichtige Maßnahmen

Die Errichtung eines Flugdaches im Umfang von 8 m × 4 m und 2,90 m H?he (hier: aufgebaut auf eine bestehende Pergola) ist ein baubewilligungspflichtige Ma?nahme.     

城市地铁地下轨道振动对周边建筑的影响分析

结合实际地铁运营期间普通整体道床、纵向轨枕减振道床的钢轨、道床、隧道壁监测点及周边建筑物在轨道不同距离监测点的典型时域波形图和频率域谱图,首先依据实际监测数据计算普通整体道床轨道与纵向轨枕轨道之间各个监测点的铅垂向计权网络最大Z振级(VLZmax),分析普通整体道床轨道与纵向轨枕轨道之间钢轨、道床、隧道壁各测点的振动最大振级差值,充分阐述纵向轨枕轨道的减震效果;然后对普通整体道床周边建筑物不同监测点的最大Z振级进行计算,确定最大Z振级范围,判定其值是否已经超过规范要求及与地铁运营轨道振动的相关性,提出减震措施建议;最后对采用纵向轨枕减振道床减震措施处理后的周边建筑物监测点进行二次监测,得到的最大Z振级监测数据均在规范允许范围以内,认识到轨枕减振道床减震技术对于易发生共振的临近建筑物减震效果最为明显。     

耦合电感低电压应力Boost变换器

提出了一种可应用于光伏发电系统的含耦合电感低电压应力Boost变换器。因传统的Z 源Boost变换器开关元件直接与负载相连而具有较高的电压应力,所提出的变换器通过耦合电感将开关元件与负载进行了隔离,可以有效减小开关元件的电压应力。新的变换器不仅保留原Z 源网络优点,同时可以在占空比相同的情况下通过调节耦合电感匝比来获得更高的电压增益。简要分析了所提拓扑的运行流程,并通过仿真验证了所提拓扑的可行性。     

矢量网络分析仪的时频域阻抗测量技术

由于传输线阻抗不连续性导致的串扰问题会严重影响信号传输的质量,从而导致信号完整性问题。从矢量网络分析仪阻抗测试原理出发,通过对比网络仪开路校准及端口补偿后的Smith圆图测量结果、阻抗和相位格式测量结果,说明网络仪频域3种测量格式所表述的阻抗信息;利用矢量网络分析仪时域变换功能从时域上对传输线进行评估,可以获得传输线阻抗不连续点和各位置阻抗信息。最后通过对一段3.5 mm传输线的测试,说明如何利用矢量网络分析仪的频域和时域同时对传输线特性尤其是阻抗特性进行评估,为传输线测试提供了一种新的方法。