牵引

In order to study the negativesequence influence to regional power grid caused by autotransformer traction power supply system, formulas of NSeq current and threephase voltage imbalance were derived, based on current distribution analysis of AT traction power supply system and singlephase VVconfiguration train substation. Employing the "train diagram" method, the realtime voltageimbalance curve was obtained in a simulation study, as well as the factors that influence NSeq and some measures to restrain it.

为研究自耦变压器牵引供电系统对地区电网造成的负序影响，首先讨论了AT牵引供电系统、单相VV接线牵引变电站的电流分布，推导得出了负序电流、三相电压不平衡度的计算公式；然后结合"列车运行图法"开发了相应的仿真程序；最后通过一个实际算例，得到了实时电压不平衡度曲线，指出了负序大小的影响因素及相应措施。

Rigid PVC pipe production line is mainly used in the manufacture of the plastic PVC pipes with various tube diameters and wall thickness in the aspects such as the agricultural and nonstructural plumbing, cable laying etc. Thin set is composed of the conical twin-screw extruder, vacuum forming table , dragger, cutter, stirring up rack etc. The screws extruder and the extractor adopt the imported AC frequency employ the superior goods. The prime mover has the traction modes such as to claw, three-claw and so on. It may choose the saw blade cutting type or the planet cutting type. It is additionally attached with measuring apparatus and the intensifying device. The unit is of the reliable performance and high production efficiency. This company may allocate the special installation for the manufacture of the inner wall spiral coil and core ply blister tube set according to the clients requirements.

硬质PVC 塑胶管材出产线主要有阿谁与出产农用给排水、建筑给排水、线缆铺设等方面的各类管径、壁厚的塑胶PVC管材，该机组由锥形双螺杆挤出机、真空定形台、牵引机、翻料架等构成螺杆挤出机及牵引机采用进***流变频调速设置，真空泵以及牵引机电均采用优质产品牵引有二爪、三爪、四爪、六爪等牵引体式格局可选用锯片或者行星切割形式，另可计长及增厚装置，机组机能可靠，出产效益高，本公司可更具客户的要求，配备布置专用装置出产螺旋消音管以及芯层发泡管机组

It could be concluded that the drawing performance and the riding comfort of the tractor-trailer combinations would been improved obviously when the optimized flexible drawgear was used.

同时发现使用经过优化设计的柔性牵引装置后不但大幅度降低了牵引架上动态纵向力的峰值，因而明显改善了挂接车辆在非平稳道路离散事件激励条件下运行时的牵引运行状况和纵向平顺性状况

When the flexible drawgear is used, the peak values both of the dynamics longitudinal force and of its instantaneous PSD have decreased largely, and the distribution status of the instantaneous PSD along both the time axles and the frequency axles have been improved. So the working stability of the tractor-trailer combinations braking process would been improved when the optimized flexible drawgear was used.

仿真分析和试验结果均表明，使用柔性牵引装置后，牵引架动态纵向力峰值及其瞬时功率谱的峰值有了大幅度的降低，动态纵向力瞬时功率谱密度沿时间轴和频率轴的能量分布得到了改善，这说明使用柔性牵引装置后有利于提高挂接车辆制动工况的工作稳定性。

The propulsion control system is one of the four subsystems of theMaglev vehicle. The propulsion control theory with field-oriented control is the key technology of the propulsion control system. In this paper,the characteristics of Maglev vehicle propulsion control system with FOC aredeeply studied and analyzed.

牵引控制系统是高速磁悬浮列车四大子系统之一，基于磁场定向控制理论的牵引力控制又是牵引控制系统的核心技术，本文深入研究和分析了在不同磁场定向控制方式下高速磁悬浮列车的牵引特性。

A device and method for preparing compound nano fiber endless tow, which contains feeding material liquid to pair of electric spinning nozzle on frame, each nozzle respectively applied with high dc voltage with opposite polarity, each pair of nozzle jetting out nano fiber with opposite electric charge, said nano fiber attracting and colliding each other to form compound nano fiber, then forming nano fiber endless tow after drawing and stretching, the first opposite set pair of electric spinning nozzle jetted compound nano fiber endless tow is stretched down and used as acceptor which covered by the nano fiber jetted by second pair of nozzle an d forming two layers of compound nano fiber endless tow after drawing and stretching, in turn to get multilayer compound nano fiber endless tow after drawing and stretching by godet roller.

复合纳米纤维长丝束制备装置及其制备方法是一种简单、高效电纺制备纳米纤维长丝束的方法，其步骤为将料液输送给支架(3)上的电纺喷头对(1)；喷口相向的电纺喷头对(1)的每个喷头分别施加相反极性的直流高电压；每对相向喷口喷出分别带相反电荷的纳米纤维，并在空中相互吸引、碰撞形成复合纳米纤维，经牵引、拉伸后形成复合纳米纤维长丝束；第一对相向放置的电纺喷头纺丝形成的复合纳米纤维长丝束向下拉伸，并作为接受体与第二对电纺喷头喷出的分别带相反电荷并相互吸引的纳米纤维在空中相遇，被第二对电纺喷头喷出的纳米纤维包裹，经牵引、拉伸后形成两层复合纳米纤维长丝束；依次类推，最后经导丝辊对(2)牵引、拉伸后得到多层复合纳米纤维长丝束。

The engine main circuit have to be gurranteed drawing the torque of electric motor and rotation speed wholly to do regulateing of independence ,But also possess extensive setting range SS7's mould electric locomotive adopts Quan Kongqiao and semi bridge accuseeing series connection to make up the monophase bridge style commutation electric circuit ,The coil power supply is encouraged against the stringtrain by the electric motor the drawing armature to 3 parallels operation ,Still there is an excitation commutation bridge ,He encourages the coil power supply with 3 electric motors drawing together to the series connection ,Moreover has one another accuses the regulating action .

机车主电路必须保证牵引电动机的转矩和转速都可作独立的调节，而且要有宽广的调节范围。SS7型电力机车采用一个全控桥和一个半控桥串联组成单相桥式整流电路，向3台并联工作的牵引电动机电枢与串励绕组供电，还有一个励磁整流桥，向串联在一起的3台牵引电动机他励绕组供电，并具有相控调节作用。可以实现机车无级调速和无级削磁。SS7型电力机车采用再生制动方式，再生制动时，牵引电动机作直流发电机工作，并且将电能馈送回接触网，此时电力机车相当于一个移动的发电站。

A kind of traction system capable of ensuring the balance of the lift cabin used in hydraulic lift is composed of support beam fixed in the lift shaft, 4 traction mechanisms separately corresponding to the four conners of the lift cabin, each of which is composed of a cylinder, several guiding pulleys and a tracting cable.

装的牵引机构，所说的每一牵引机构都包括一个固定安装在支梁上的带滑轮的油缸，若干个也安装在支梁上的导向滑轮和三条曳引绳，所说的其中一条曳引绳烧着本牵引机构所属的油缸上的滑轮及导向滑轮，一端与本牵引机构所对应着的电梯轿厢

Table 2.2 Infrastructure in different transport modes Road - Public No inherent guidance Infrastructure provided - Private Artificial, shared way centrally at public expense and at nominal cost to users Rail -Heavy Inherent guidance Track and control centrally - Light Artificial, dedicated way provided and charged to - Metro operators at full cost or owned by operators Air Natural, shared way Infrastructure provided by third party at full cost Maritime -Coastal/short Natural, shared way Infrastructure provided by sea No inherent guidance third party and charged at full Deep sea cost Inland water Natural or man-made Infrastructure provided by shared way third party and charged at full No inherent guidance cost Pipelines Artificial, dedicated way Infrastructure usually Inherent guidance provided by user All modes (except pipelines, although a travelator or moving walkway' may be considered a pipeline) carry both freight and passengers.

表2.2 不同运输方式的基础结构公路公共私人没有固有的牵引人造的，共享的方式基础设施由中央以公共费用和以使用者名义上的成本来提供铁路重型轻型地铁固有的牵引人造的，独占的方式铁轨和控制设施以完全成本的形式提供和向运营者收取费用或者由运营者所独有航空自然的，共享的方式基础设施由第三方提供并以完全成本方式收取费用海运沿海／近洋远洋自然的，共享的方式没有固有的牵引基础设施由第三方提供并以完全成本方式收取费用内河水运自然或人工的，共享的方式，没有固有的牵引基础设施由第三方提供并以完全成本方式收取费用管道人工的，专属的方式固有的引导基础设施通常由用户提供所有的运输方式（除了管道，尽管自动扶梯也可以被看作是一种管道）既能载人也能载货。

Materials And Methods 1, The animal model of Sprague-Dawley rat for maxillary protraction was made in this study, and an appliance based on the principle of protraction headgear was designed and made for maxillary protraction treatment which was hooked over the front of the zygomatic arch ,and a hole was made on the skull in the experimental group rat .

以面具式前牵引矫治器为原理制作特殊的前牵引支架，以外科方法安装支架挂在大鼠颧弓前端，在实验加力组大鼠头颅上打孔，安放挂钩，通过弹性牵引提供支架向前牵引的支抗。2、以该动物模型为基础，选用90只五周龄的Sprague—Dawley健康雌性大鼠作实验动物，随机分到实验加力组、正常对照组、手术对照组。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。