Experimental Study of Electromagnetic Interaction Between a Permanent Magnet and an HTS Coil

Journal of Superconductivity and Novel Magnetism - Many applications of superconductivity involve the interaction between superconductor coils and magnet or magnetic field. The electromagnetic...     

成层式铝蜂窝夹芯结构冲击响应试验研究

以牺牲层设计为背景,提出一种成层式铝蜂窝夹芯结构。通过两种能级的落锤冲击试验,得到不同组合试件的局部冲击响应结果。根据能量吸收、荷载峰值、冲头位移和背板挠度的对比分析,得出以下结论:结构在相对较低能级(17~83J)的冲击作用下,除了永久塑性变形,也伴随着一定的弹性变形;同时,在芯层质量相同的前提下,可优先选择胞元较小、高度较低的蜂窝作为单层结构的芯层;全贯穿临界值应当介于83~119J之间,在设计牺牲层时,局部冲击的极限能量设计值应当低于该临界值;芯层的相对密度对抗局部冲击性能的影响较为明显;根据牺牲层的设计标准,在本文的局部冲击试验研究范围内,AB、BA、ABA型结构在综合指标上具有相对优势。研究结果可为成层式铝蜂窝夹芯结构在防护工程中的应用提供参考。     

Experimental results of tri-axial HTS cable

Recently, a tri-axial cable composed of three concentric phases has been intensively developed, because it has advantages such as reduced high-temperature superconducting (HTS) tape, small leakage field and small heat loss as compared to three single-phase cables. However, there is an inherent imbalance in the three-phase currents in tri-axial cables due to the differences in the radii of the three-phase current layers. The imbalance of the currents causes additional loss and a large leakage field in the cable, and deteriorates the electric power quality. We have already proposed that it is possible to obtain a balanced three-phase distribution by adjusting all of the twist pitches. In order to verify the theory, we designed and fabricated a 1-m-long tri-axial HTS cable and carried out the cable test. The balanced three-phase voltages of the cable were measured by supplying an AC transport current with frequency from 50 to 500 Hz at 77 K. It is found from the test results that the balanced three-phase distributions can be realized by adjusting all of the twist pitches.     

Conceptual Design of a Field Coil for 5 MW HTS Synchronous Machine

Compared with a conventional rotating machine, a superconducting rotating machine fabricated by High Temperature Superconducting (HTS) tape has superior performance and efficiency due to the HTS field coil for the rotor which can generate high magnetic flux intensity. The two primary factors for the design of the HTS rotational machine are how to construct the optimal magnetic field path through the air gap located between the rotor and the stator and how to enhance the linkage magnetic flux density between the armature coil in the stator and the field coil in the rotor. A 5 MW HTS motor for ship propulsion is planned for development in early 2011 by a Korean collaboration group of KERI and DOOSAN Heavy Industry. As a part of this R&D efforts, we designed and analyzed the field coil for a 5 MW HTS synchronous motor. In this paper, the computational results of the magnetic field distribution on the whole winding regions of the HTS field coil of the superconducting rotating machine will be also presented and discussed.     

An Adaptive Time Stepping Method for Transient Dynamic Response Analysis

An efficient adaptive time stepping method is proposed for transient dynamic response analysis, which is frequently encountered in civil engineering and elsewhere. The reduced problem following the spatial discretisation can be discretised in the time by a $C^0$-continuous discontinuous Galerkin method, and the adaptive time stepping strategy is based on optimal a posteriori error estimates developed using the energy method. Some numerical experiments demonstrate the effectiveness of our approach.     

An Experimental Investigation of the Long-Term Stability of Triple-Point-of-Water Cells

Contamination of triple-point-of-water (TPW) cells by the chemical components of the borosilicate glass that contains the water is now widely recognized as the principal contributor to long-term drift of the cell temperature. To add to the available experimental data, a comparison of 24 TPW cells of various ages (from 10 years to 59 years), manufacturers (NRC, Jarrett, Isotech), and materials (borosilicate glass and fused quartz) was undertaken in 2013. Twelve cells from this group were compared to one another in 1997. By comparing the current inter-cell temperature differences to those determined 16 years earlier, it was found that some cells have remained stable, others have become colder (as might be expected from ongoing dissolution of the glass), and one or two show an apparent increase in temperature that seems anomalous. Also included among the 24 cells are five cells of borosilicate glass and five of fused quartz that were purchased 10 years ago. By comparing the relative temperature differences among this group of borosilcate and fused-quartz-encapsulated cells to the values obtained when they were last compared 6 years ago, it was found that the average temperature of the borosilcate group of cells decreases by \(-6\,\upmu \mathrm{K}\,{\cdot }\,\mathrm{year}^{-1}\,({\pm }2\,\upmu \mathrm{K}\,{\cdot }\,\mathrm{year}^{-1})\) , in reasonable agreement with an average drift of \(-4\,\upmu \mathrm{K}\,{\cdot }\,\mathrm{year}^{-1}\) suggested 12 years ago. It was concluded that fused quartz is the superior container for TPW cells.     

An Experimental Investigation and Analysis of PTAW Process

Experiments are conducted to deposit SS304 L powders on SS316 plates by plasma transfer arc welding process with varying four input process parameters, namely scanning speed, powder feed rate, stand-off distance, and current. The effects of these four input process parameters on deposition geometry, dilution, and bead continuity are investigated in this study. Attempts have been made to explain the experimental results with only two compound parameters, “energy deposition per length” and “powder deposition per length” instead of four independent input process parameters. It is observed that the variation of dilution is very little when the scanning speed increases from 100 to 600 mm/min and other process parameters remain constant. When the powder feed rate increases and other parameters remain constant, initially the dilution decreases rapidly and attains a minimum value which do not change further with increase in powder feed rate. It is also observed that the dilution remains almost constant around 6–9% as the stand-off distance changes from 7 to 11 mm and other process parameters remain constant. The formation of nonuniform bead is found to be due to insufficient energy deposition per length per mass of supplied powder.     

适用瞬态响应计算的火箭结构动力学模型修正方法

大型火箭结构十分复杂,其连接型式多,存在多分支结构。分析火箭结构中存在弱刚度的内-外翻边连接、螺栓点连接等典型连接型式,基于元素型法,以这些部位刚度为修正参数,开展动力学模型修正方法研究。结果表明,采用的方法能保证修正后模型的物理意义和真实性,能够适用于瞬态外激励作用下的结构响应计算,特别是内力响应计算。修正后模型的各阶模态结果和试验吻合较好,且与实际试验中瞬态响应的实测结果相比,计算具有较高精度,能够满足工程需求。     

Fire Burnthrough Response of CFRP Aerostructures. Numerical Investigation and Experimental Verification

Aircraft structures are designed to withstand further to dynamic mechanical loadings thermal loads too. In the event of an external fire (while the aircraft is on the ground) the fuselage structure has to withstand and delay fire penetration. Prolonged burnthrough time is the design target. In the current work, a progressive fire-degradation material model is developed that links decomposition kinetics with the thermophysical properties of polymer composite materials. The material model is then implemented in a FE model to simulate the response of the flat panels under fire burnthrough conditions. Experimental investigation is performed in accordance to the ISO2685:1998 (E) Standard.     

YBCO高温超导微带线的非线性光响应特性实验及其应用分析

研究了在波长为0.68μm的连续激光辐照下, YBCO高温超导薄膜微带线结构的光致非线性效应,并从实验现象和高温超导光响应器件研制两个角度进行讨论.主要的研究结果如下:高温超导薄膜微带线结构的非平衡光响应存在阈值,在本实验条件下,当功率＜15mW时,以辐射热效应为主;当功率＞15mW时,出现非平衡光响应.该阈值的获得,对光响应超导器件的设计与制作具有重要指导意义.在此基础之上,设想了一种新型的高温超导衰减器;另外,在反复通断激光实验中,观察到YBCO微带线具有时间累积的记忆效应,从而导致回复时间的出现.该现象也是影响高温超导光响应器件性能的重要因素之一,对非线性光响应超导器件的发展具有重要价值.     

新型动静压挤压油膜阻尼器减振特性的实验研究

以小孔节流的新型动静压挤压油膜阻尼器（ＨＳＦＤ）为例，从实验上研究了ＨＳＦＤ对柔性转子系统振动的控制能力，并与传统挤压油膜阻尼器（ＳＦＤ）的减振特性进行了比较。结果表明了与ＳＦＤ相比，ＨＳＦＤ能够明显地改善ＳＦＤ的非线性特性，是一种具有良好减振特性的阻尼元件。     

Experimental Investigations on the Critical Current of the Jointed Bi-2223/Ag HTS Tapes

This paper summarizes the experimental investigations on the critical current of two jointed Bi-2223/Ag superconducting tapes connected by Sn63Ag2Pb solder. Different lap lengths of contact surface were studied. The joint resistance was measured to be in the range of 0.059??0.76????, and the critical current of the jointed Bi-2223/Ag HTS tapes was measured with different charging rates using standard four-point-method in a zero-applied magnetic field applying 1 ??V/cm criterion. The experimental results showed that the longer the lap length was, the smaller the joint resistance was and the nearer the critical current approached that of Bi-2223/Ag superconducting short-sample. On the other hand, the critical current decreased with the increasing of the charging rate.     

表面活化沸石外比表面积的试验研究

利用阳离子表面活化剂(HDTMA Cl)对天然沸石进行了表面活化改性,并使用BET法测定了表面活化沸石颗粒(SMZ)和天然沸石颗粒的外比表面积,试验结果表明,粒径为4～100目时,天然沸石的比表面积为13.44～14.32m2/g,活化沸石的比表面积为4.18～6.79m2/g,与天然沸石相比较,其值要小1～2倍。通过轻拍式原子力显微镜镜像分析(TMAFM),探讨了SMZ外比表面积发生变化的原因。     

35kV冷绝缘高温超导电缆的雷电冲击特性研究

为了优化35kV冷绝缘高超导交流电缆的绝缘设计,研究了聚丙烯层压纸(PPLP)在液氮环境中的绝缘特性,得到了它在液氮环境中的交流耐压绝缘强度和雷电冲击绝缘强度。根据实验结果和35kV纸绝缘电缆的国家标准,设计了35kV冷绝缘高超导交流电缆主绝缘、应力锥的形状、样品的长度并且绕制了该电缆的试验样品。最后对电缆样品进行了雷电冲击试验,样品通过试验验证,表明电缆的设计完全符合国家标准要求。     

动圈－橡胶结构振动特性的实验研究

针对调制气流声源中动圈－橡胶结构振动系统,利用电涡流传感器构建振动位移测量实验平台,对橡胶硬度分别为40 o和50 o的系统振动特性进行相关研究。结果表明,该系统在恒流激励下可近似为单自由度系统;在小变形范围内,主共振频率上升梯度随预压量的增大而减小;50 o橡胶对应的系统有效频率范围优于40 o橡胶;激励信号的大小会改变橡胶的等效刚度,激励越大,刚度越小;在初始小变形工况下,增大橡胶预压量可改善位移谐波失真。     

Transient Elastic Impact Response of Slender Graphite Rods

Graphite rods are manufactured by extruding the mixture of calcined petroleum coke and coal tar pitch into the desired shape and baking the cooled specimens at about 800°C. Cracking can occur in rods during the manufacturing process. It is useful to be able to detect the presence of such cracks in the rods prior to their being machined and put into use as electrodes or cathodes or thermal insulator. In an effort to develop a nondestructive testing approach to evaluation of the rods, transient elastic impact was determined for slender rods. Theory for solid, slender rods provided an important starting point for this work. Subsequently, numerical models were developed and simulation was used to determine the response of rods containing cracks. Experiments on graphite rods with and without cracks were conducted and the internal condition determined from the recorded signals. The rods were then cut lengthwise to reveal the internal condition and verify the predicted results. In all cases the knowledge gained from simulation allowed for the presence of cracks to be detected.     

Identification of the Transient Response of a Capacitive Relative Humidity Sensor

Measurement Techniques - This paper presents the results of identifying the transient response of a relative air humidity sensor. It is shown that the capacitive relative humidity sensor is an...     

垂直简谐激励下阻尼颗粒动态特性研究

在垂直简谐激励条件下,通过稳态功率输入法对颗粒阻尼纵向耦合结构系统的动态特性进行了研究和分析。实验结果表明,在简谐激励作用下由颗粒体引起的周期脉冲力对系统的损耗功率并不产生影响,损耗功率只与激励频率有关。由颗粒体产生的损耗功率和附加质量存在明显的临界点(转捩点)现象,在临界点之前,阻尼颗粒不损耗能量,附加质量变化不明显;临界点之后,损耗功率随激励强度增加而增大,附加质量随激励幅值的增加而变小,且对激励频率的变化不敏感。最后,通过阻尼颗粒的相态特性对出现临界点值现象加以解释。