An Attentive Problem of 35 kV Power Lines in Mountain Area on Protecting Against

To counteract capacitive current and resume power system, the neutral point of 35 kV power system at the mountainous area is grounding through the arc winding widely. In fact, there is great difficult in selecting the arc winding to satisfy the requirement of system. In a 35 kV power system which neutral point is grounding through the arc winding, the capacitance current are measured in site when a single-phase is grounding. From the measure data, the imbalance of three-phase voltage whether the arc winding exist or not and the operating situation of arc winding are discussed, and bring forward an attentive problem about operation of arc winding and decrease of lightning outage rates.     

用喷气-环锭和喷气-络筒技术减少麻纱线毛羽的研究

喷气-环锭和喷气-络筒是一种简单、低成本的减少纱线毛羽的新方法。我们对其进行理论和实验研究。采用数值模拟的方法，对毛羽在喷嘴内的运动进行模拟，说明了利用喷嘴减少毛羽的机理。根据数值模拟的结果，我们预测了喷嘴参数对减少毛羽的影响，并以麻纱为对象，用实验的方法研究了喷气-环锭和喷气-络筒技术对减少纱线毛羽的效果以及参数影响，实验与理论研究的结果相符。     

Research of the winding ratio to prevent yarn overlapping

Unapt winding parameters may cause yarn overlapping with the problems of low yarn density, winding vibration, breaking and disorder when unwinding yarn and others. The yarn arrangement rules and its relationship with the winding ratio are analyzed using geometrical and mathematical methods. It is revealed that winding ratio is an important parameter to prevent yarn overlapping. When the winding ratio is proper, the yarn can be staggered regularly and yarn overlapping can be prevented effectively. A new method for the determination of the proper winding ratio is introduced. The alteration of yarn angle and interval and their effect for the determination of the winding ratio are discussed. The particular process of the method is given and an example is presented.     

秸秆圆捆机捆绳机构的参数优化与试验

针对我国中小型圆捆机收获的秸秆捆易于膨胀松散、甚至散捆的问题,设计了一种与钢辊式圆捆机相配套的捆绳机构。在秸秆捆力学特性测定及其膨胀变形影响因素分析的基础上,利用钢辊式圆捆机试验台,选取影响捆绳机构性能的导绳轮半径、链轮中心距圆捆机侧壁的安装距离、以及捆绳在秸秆捆端部缠绕的圈数作为试验因素,以秸秆捆膨胀率和捆绳消耗量为评价指标进行试验研究。结果表明:对秸秆捆膨胀率贡献率依次为安装距离、导绳轮半径、圈数;对捆绳消耗量贡献率依次为导绳轮半径、安装距离、圈数。当试验因素参数组合为圈数2圈、导绳轮半径70 mm、安装距离62 mm时,秸秆捆膨胀率为4.42%,捆绳消耗量为2.93 kg/t。研究结果可为圆捆机捆绳机构的研究和设计提供理论及技术依据。     

竹缠绕复合管弯曲强度测试

分别测试以轴向竹篾卷、环向竹篾卷制作的竹缠绕复合管弯曲强度,从正面（管外表面）和背面（管内表面）进行测试。结果表明：轴向试件正面向上弯曲强度为42.80 MPa,背面向上弯曲强度为41.02 MPa,环向试件正面向上弯曲强度为13.28 MPa,背面向上弯曲强度为10.38 MPa。试验结果可为竹缠绕复合管结构设计提供依据。     

生物质缠绕房屋将变革传统住宅建造方式

生物质缠绕复合材料技术是2007年发明的竹缠绕复合材料技术的延伸。文章概述了生物质缠绕复合材料的内涵,具体介绍了生物质缠绕房屋的概念、独特优势、研发现状及环境意义,并阐述了生物质缠绕房屋替代传统砖头瓦片、钢筋混凝土结构房屋的发展趋势,分析了生物质缠绕房屋产业形成的基础条件。     

混合励磁电机的研究现状及进展

论述了混合励磁电机的研究现状,分析了混合励磁电机的磁场调节原理及其特点,指出了其应用前景．     

“曲水流觞”园林景境营造的现代转译

自上古的巫礼习俗到秦汉六朝的文赋序跋,再到两宋时期的文人图画,最后到三维的景境空间“曲水流觞”附加在不同的“形式”上进行了3次转译。综合分析“曲水流觞”在不同题材文艺作品中所呈现的艺术内涵,同时结合现存的不同时代的景观实例,评价其景境营造的优劣,得出景境“曲水流觞”的转译需要结合时代的异质性,在景观创新的过程中传承历史的文化美学价值。最后提出,现代风景园林的景观营造,应从生境、画境、意境3个层面推敲考量,以古为新,创新性的营造本土景观。     

Simulation analysis of the thermal-electric analogy calculation model of transformer winding hot-spot temperature

The winding hot-spot temperature is one of the most critical parameters that determines the power transformer overloading capability and the aging rate of the oil-paper insulation. Based on the traditional thermal theory, the paper proposes a simulation model to predict transformer winding hot spot temperature taking into account oil viscosity changes with temperature, and combined with the thermal-electric analogy method and hot spot temperature rise model recommended by IEEE. The Runge-Kutta method is used to calculate top-oil temperature and winding hot-spot temperature of the transformer, and then compare them with the measured data obtained from the 100 kVA/5 kV (ONAN) experimental transformer. The simulation results are in good agreement with experimental data.     

同步发电机励磁绕组匝间短路故障在线分析方法综述

励磁绕组匝间短路是同步发电机常见故障之一。为保证机组和电网的安全可靠运行,有必要对该故障进行在线分析检测。首先介绍了应用于同步发电机励磁绕组匝间短路故障在线分析的磁场-电流谐波分析法、探测线圈法、多回路法、输出电气量分析法、振动分析法等的研究现状,并对几种方法进行了比较,然后对未来在线分析方法的发展方向进行了展望,对输出电气量分析法提出了两条研究思路,最后说明了在线分析方法应具有实际可行性和多用途性。