用可移动电流丝方法重建HL-2A等离子体边界的研究

根据Shafranov电流密度矩理论，给出了用可移动电流丝方法重建HL-2A装置等离子体边界的具体计算方法，研究了用可移动电流丝方法(VCF法)重建边界的可行性.VCF法与固定电流丝方法(FCF法)和有限电流元法(FCE法)相比，最大的优点就是用1—3个可移动电流丝就可以准确地重建位置和小半径快速变化的等离子体位形，这正好弥补了FCF法的不足.将可移动电流丝方法和FCF法相结合，可以实现全程等离子体放电的边界实时显示和等离子体的位形控制. 关键词： 可移动电流丝方法 边界识别     

用丝电流方法快速识别HL-2A等离子体边界

利用等离子体外部测量的磁场信号,使用丝电流方法对HL-2A等离子体边界进行了快速识别。介绍了该方法的原理、相关的测量系统配置和该程序的研制进展。对识别结果进行了讨论。     

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利用电流丝模型对SUNIST球形托卡马克等离子体边界重构进行了模拟计算。结果表明,用电流丝模型能够比较好地对等离子体自由边界进行快速识别,与EFIT平衡计算的边界径向平均误差小于6mm。     

FBI程序对HL-2A装置等离子体边界计算的初步结果

JT-60U装置上的FBI程序是运行于UNIX操作系统下综合的等离子体参数计算系统，该程序已在HL-2A装置上采用了，其主要计算模块的功能是使用等离子体边界外的电磁测量信号，利用丝电流方法识别等离子体边界。程序引进时最大程度地考虑了两个装置电磁测量系统、装置尺寸结构和线圈系统的不同而进行了修改。     

物理学中条件极值的求法

本文利用隐函数存在与唯一性的条件，把它化为一元函数，从而使条件极值问题转化为无条件极值问题，进一步用待定乘数法解极值，并举例说明它在物理学中的应用。     

Plasma Boundary Identification by Using Filament-Current Method on HL-2A Tokamak

The establishment of a divertor configuration is a task for a divertor tokamak. To achieve this goal, we have to identify plasma boundary at first. So, it is important to find a quick approach to calculate plasma boundary and other global parameters. Various methods     

开边界六顶角模型的边界关联函数

讨论了具有开边界六顶角模型的关联函数，计算了涉及边界自发极化的边界关联函数，得到了它们的行列式表示. 关键词： 六顶角模型 关联函数 开边界     

可积开边界条件下XXX-1/2自旋链模型的Gaudin公式

利用量子空间可因式化F算子,在量子反散射的框架内计算出了可积开边界条件下XXX12自旋链模型的Bethe态的标量积和模,得到了用谱参量函数的行列式表达的开边界条件下的Gaudin公式. 关键词： 可积模型 关联函数 开边界     

HL-2A等离子体边界识别的研究

利用电流丝模型编写的电流丝编码和采集到的18个磁探针测量数据、等离子体电流和极向场线圈电流的数据做了重建HL-2A等离子体边界的研究。计算结果表明,电流丝编码能够正确地识别等离子体的边界、偏滤器位形和X点的位置。计算获得的偏滤器内外靶板上打击点出现和消失的时间与布置在偏滤器靶板上静电探针测量到的信号很好地符合。在Pentium 4的PC个人计算机上(CPU为2.4GHz, 800MHz总线)计算每一个时刻的等离子体边界时间小于1ms。     

用有限电流元法识别HL-2A 装置的等离子体边界

在电流丝模型对HL-2A装置等离子体边界重建取得满意结果[3]、[5]的基础上，本文用有限电流元模型对HL-2A等离子体边界进行了重建研究。计算和实验结果表明，在通常情况下，有限电流元模型比固定电流丝模型的重建误差稍小，前者误差小于3mm，后者误差小于6mm。当部分有限电流元分布在等离子体边界之外时，用有限电流元模型仍然可以成功重建边界。有限电流元的位置在一定范围内变化时，重建的误差都很小。用普通奔腾4 2.4GHz PC机计算一组等离子体放电边界的时间不超过1ms。有限电流元法能准确而快速地识别等离子体的偏滤器位形，这对于HL-2A装置的实时位形控制是基本和重要的。     

HL-2A等离子体边界识别的模拟研究

采用电流丝模型对HL-2A等离子体边界重建做了模拟计算。结果表明,对于孔栏位形、双零位形和下单零位形,重建的等离子体边界与平衡计算的边界能很好地吻合,最大径向距离小于8mm。     

Deriving correction functions to model the efficiency of noise barriers with complex shapes using boundary element simulations

The boundary element method (BEM) is a commonly used method to compute the insertion loss of noise barriers having arbitrary cross-sections. For large scale three-dimensional problems, however, the BEM is not feasible. On the other hand, standardized calculation methods for noise mapping are efficient, but shapes other than the straight barrier cannot be properly calculated. Attempts to merge these two approaches by using BEM to derive correction functions based on geometrical quantities such as source and target angle as well as the path length elongation between source and receiver caused by the barrier were usually focused on a small set of barrier types, dimensions, absorptive configurations, source or receiver positions. The main objective of this study is to investigate which functions based on the most common geometrical parameters are well suited for approximating the efficiency of different types of barriers, dimensions and absorptive configurations. To achieve this, numerous combinations of 7 different barrier types, different heights and widths as well as 3 different absorptive configurations were simulated using the 2D BEM for 8 different source positions. The octave-band-wise efficiency, i.e. the frequency-dependent gain in insertion loss compared to an equally high, fully reflective straight barrier was used as a basis for the correction functions. Linear as well as polynomial models were compared yielding a polynomial of third degree in the source and fourth degree in the target angle as the best model. Effects on the error using uniform sampling in the target angle instead of a uniform receiver grid as a basis for the correction functions are also investigated. Furthermore, wide-band efficiencies based on standardized traffic emission spectra are calculated showing small errors compared to single-band errors, in particular in the high-frequency range. A linear interpolation scheme is suggested to deal with barriers having dimensions not simulated in this work.     

基于电流丝法的多级同步感应线圈炮电枢温升计算

针对同步感应线圈炮常用的导体圆筒式电枢,结合电流丝法,建立了电枢温升计算模型;通过搭建三级同步感应线圈炮试验平台,验证了计算模型的正确性,并分析了电枢材料和剖分设置对电枢温升计算的影响。结果表明：发射过程中电枢的最高温升位于其底部外侧,电枢前端也有较高温升;当调节载荷使铜、铝电枢等质量时,前者的温升虽然更高,但温升对其发射效率的影响却小于后者,这是因为铜的电阻率温度系数小于铝;电枢的剖分设置对电枢温升的计算的影响比较明显。因此从电枢温升对发射过程的影响来看,铜电枢比铝电枢更适合用于高速发射。     

Assessing the effect of a barrier between two rooms subjected to low frequency sound using the boundary element method

The boundary element method (BEM) has been used to compute the acoustic wave propagation through a single vertical panel, which separates two rooms, made of concrete, when one of the rooms is excited by a steady-state, spatially sinusoidal, harmonic line load pressure at low frequencies. This work focuses on how the connection of the panel to the ceiling affects the acoustic insulation provided by the wall. Perfect double-fixed partitions and acoustic barrier-type structures with differently-sized gaps between the ceiling and the barrier are studied. The BEM model is formulated in the frequency domain and takes the air-solid interaction fully into account. Insulation dips are localised in the frequency domain and identified with dips associated with both the wall's natural dynamic vibration modes and with those associated with the air in the rooms. The influence of the wall's thickness on acoustic insulation is also analysed. The computed results obtained with the acoustic barrier type structure are compared with those obtained by a rigid model. The importance of the rooms' surface conditions is assessed, modelling the rooms with cork.     

A smoothing technique for discrete delta functions with application to immersed boundary method in moving boundary simulations

The effects of complex boundary conditions on flows are represented by a volume force in the immersed boundary methods. The problem with this representation is that the volume force exhibits non-physical oscillations in moving boundary simulations. A smoothing technique for discrete delta functions has been developed in this paper to suppress the non-physical oscillations in the volume forces. We have found that the non-physical oscillations are mainly due to the fact that the derivatives of the regular discrete delta functions do not satisfy certain moment conditions. It has been shown that the smoothed discrete delta functions constructed in this paper have one-order higher derivative than the regular ones. Moreover, not only the smoothed discrete delta functions satisfy the first two discrete moment conditions, but also their derivatives satisfy one-order higher moment condition than the regular ones. The smoothed discrete delta functions are tested by three test cases: a one-dimensional heat equation with a moving singular force, a two-dimensional flow past an oscillating cylinder, and the vortex-induced vibration of a cylinder. The numerical examples in these cases demonstrate that the smoothed discrete delta functions can effectively suppress the non-physical oscillations in the volume forces and improve the accuracy of the immersed boundary method with direct forcing in moving boundary simulations.