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Error field caused by non-coaxiality among poloidal and toroidalfield coils on HL-2M tokamak is calculated with SURFMN and SURFMN_TFCOIL code. According to the coil installation error chosen by international tokamak and the installation experience of HL-2A tokamak, the maximum shift distance of poloidal- and toroidal-field coils on HL-2M tokamak is chosen 3~8mm , and the maximum tilt angle of that is 0.05~0.1 degree. The probability density and accumulative probability of error field are calculated with the maximum shift distance 3mm , 5mm and 8mm respectively, and the maximum tilt angle 0.05, 0.075 and 0.1 degree respectively. The results show that: (1) the probability density distribution become flat and the range of error field B3-mode/BT is enlarged significantly with the increase of maximum shift distance of field coils; (2) the shift of poloidal- and toroidal-field coils influences error field more heavily than tilt does; (3) when the shift of poloidal- and toroidal-field coils reaches 5mm , especially 8mm , the error field is more possibly reach 2×10-4. 相似文献
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Acoustic bands are studied numerically for a Lamb wave propagating in an anti-symmetric structure of a one-dimensional periodic plate by using the method of supercell plane-wave expansion. The results show that all the bands are pinned in pairs at the Brillouin zone boundary as long as the anti-symmetry remains and acoustic band gaps (ABGs) only appear between certain bands. In order to reveal the relationship between the band pinning and the anti-symmetry, the method of eigenmode analysis is introduced to calculate the displacement fields of different plate structures. Further, the method of harmony response analysis is employed to calculate the reference spectra to verify the accuracy of numerical calculations of acoustic band map, and both the locations and widths of ABGs in the acoustic band map are in good agreement with those of the reference spectra. The investigations show that the pinning effect is very sensitive to the anti-symmetry of periodic plates, and by introducing different types of breakages, more ABGs or narrow pass bands will appear, which is meaningful in band gap engineering. 相似文献
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外海波浪作用下海堤越浪是一个复杂的水动力学过程,越浪量则是评估海堤安全的重要因素之一。离岸式潜堤作为一种典型的护岸工程结构物,已被应用于淤泥质海岸复合式海堤工程,其主要作用是促淤保滩和降低越浪量。本文针对不同的潜堤与海堤距离以及不同的潜堤高程,进行了规则波作用下越浪量系列物理模型实验,给出了各工况下的实测越浪量。实验结果表明:潜堤是否导致波浪破碎是控制海堤越浪量的主要因素之一;当潜堤使得波浪破碎时,潜堤位置对海堤越浪量有较大影响。潜堤与海堤距离接近1/2波长时越浪量偏大。 相似文献