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71.
介绍了一种输出峰值功率在MW量级,工作频率和脉冲宽度均连续可调的高功率固态脉冲调制器的设计。脉冲调制器的放电回路采用先进的固态开关技术,以实现频率和脉宽的连续可调。调制器输出采用升压型多路初级绕组脉冲变压器,以降低励磁单元的工作电压和工作电流,同时避免了由于固态开关串并联而导致的电路复杂设计问题。系统采用在励磁回路中添加补偿网络的方法提高输出脉冲的平顶度。采取以上这些技术设计的固态调制器工程样机输出脉冲峰值电压为48 kV、宽度1.0~4.5μs、重复频率20~300 Hz、脉冲顶降小于1%,可以作为磁控管调制器应用在粒子加速器系统中。 相似文献
72.
We proved that there exists a family of complete oriented minimal surfaces in R3 with finite total curvature-4nπ,each of which has 0 genus and two ends,and both of the ends have winding order n,where n ∈ N,and discussed the symmetric property for special parameters. 相似文献
73.
74.
复合材料力矩管扭转性能的研究 总被引:1,自引:0,他引:1
为了研究缠绕角度对玻璃纤维增强复合材料管(GFRP)扭转性能的影响和给在实际应用中提供依据,本文研究采用湿法缠绕成型工艺制得了具有不同缠绕角度的GFRP管.通过测试缠绕管的破坏扭矩来分析影响复合材料缠绕管扭转性能的各项因素,并与理论计算值进行了比较.研究结果表明,缠绕管扭转破坏的主要形式为面内剪切破坏.当缠绕角度在25°至60°范围内变化时,随着缠绕角度的增大,复合材料缠绕管的壁厚逐渐减小,抗剪性能逐渐减弱且扭转破坏形式有分层情况出现.当缠绕角是25°时,缠绕管的抗扭性能最佳,最大扭矩为118N.m,对应的扭转强度为209MPa. 相似文献
75.
研究了大型汽轮发电机定子端部固定绕组的压板松动时,位于两侧压板间某段绕组的振动问题.首先,采用分离变量法,给出了发电机运行时定子端部绕组区域的磁感应强度表达式,并给出了绕组所受电磁力及与松动压板间摩擦力的计算式.其次,建立了研究绕组非线性振动问题的力学分析模型,采用多尺度法对主共振情形进行了解析求解,推得了稳态运动下的幅频响应方程,并对定常解的稳定性及分岔奇异性进行了研究,得到了稳定性的判定条件及分岔方程的转迁集.最后,针对工程实际问题进行了计算,给出了相应的幅频响应曲线图,并进行了分析讨论. 相似文献
76.
V. P. Stavrov A. V. Markov A. V. Zhernovskii K. F. Friedrich 《Mechanics of Composite Materials》2000,36(3):249-254
The problem of compression of a unidirectional layer and shear of a polymer interlayer during winding of rings is considered.
The equations determining the dependence of the layer thickness and stresses on the parameters entering into the power flow
law for a prepreg and polymer matrix and on the basic parameters of the winding process—the initial tension of the prepreg,
its placement rate, and the radius of a mandrel—are derived. The ring thickness measurements obtained at various temperatures
and initial tension forces of plies confirm the adequacy of the model offered. It is found that the viscous properties of
the prepreg and matrix upon winding affect the relative change in the layer thickness to a greater extent than the stresses
in these layers. With increase in temperature and tension force upon winding, the effect of viscous deformations of the prepreg
and matrix increases. A decrease in viscosity and an increase in the tension force of the tape lead to a higher strength of
the ring in tension and interlaminar shear; however, the growing percolation of the polymer melt leads to a greater inhomogeneity
of the structure of the composite in the ring and to a lower reinforcing effect of the factors mentioned.
Presented at the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000).
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 3, pp. 419–428, 2000. 相似文献
77.
78.
Primordial black hole formation by cosmic string collapses is reconsidered in the case where the winding number of the string
is larger than unity. The line energy density of a multiple winding string becomes greater than that of a single winding string
so that the probability of black hole formation by string collapse during loop oscillation would be strongly enhanced. Moreover,
this probability could be affected by changes in gravity theory due to large extra dimensions based on the brane universe
model. In addition, a wider class of strings which are stable compared to conventional cosmic strings can contribute to such
a scenario. Although the production of the multiple winding defect is suppressed and its number density should be small, the
enhancement of black hole formation by the increased energy density may provide a large number of evaporating black holes
in the present universe which gives more stringent constraints on the string model compared to the ordinary string scenario. 相似文献
79.
80.
Using constrained path integrals, we study the winding angle distribution of a two-dimensional Brownian motion around a given point. By a careful analysis of the spectral properties of some Schrödinger-like Hamiltonians, we obtain a generalization of the Messulam-Yor law. Various limiting cases are considered. 相似文献