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The period length is usually much larger than the cavity effective length in a low energy superconducting linac.The long drifts between cavities will not only decrease the acceptance of the linac, but also lead to possible instability. The linac will be more sensitive to mismatch and other perturbations. From the longitudinal motion equation, the function which describes the parametric resonance is deduced and the relation between the instability region and the cavity filling factor is discussed. It indicates that if the zero current phase advance per period is kept below 90°, instability driven by parametric resonance will never occur. The space charge effect will enhance the instability, so that a stricter limitation on the phase advance per cell is required. From the numerical simulation results for two different schemes of Injector-Ⅰ of the C-ADS driver linac, one can find that even with just three cells in the unstable region, significant emittance growth can be observed. Further investigations show that it is apt to produce halo particles under resonance, and the machine becomes more sensitive to errors and mismatches. Therefore, it is important to keep all cells in the stable region throughout the linac of very high beam power to minimize beam losses. 相似文献
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今年,诉讼法的修改已列入全国人大的立法议程中,随之而来的一些诉讼法方面问题的讨论也更加热烈起来.本文对证人制度的完善提出几点建议,以期能够最大程度的契合我国的现实情况. 相似文献
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研究了不确定同时取送货车辆路径问题(VRPSPD),考虑运行环境的不确定性,顾客时间窗口要求和对顾客同时进行取货和送货服务的情况,以运作成本最低和顾客满意度最高为决策目标,构建不确定VRPSPD数学模型。模型中,引入模糊随机理论来描述决策环境中的双重不确定性,假定顾客需求量(送货量)和取货量是模糊随机变量。随后,提出基于模糊随机算子的改进粒子群算法对模型进行求解。为了适应模型特点和提高算法效率,设计合理的编码和解码过程,制定多个适应度函数方案处理多目标问题,并应用更加科学的更新策略。最后在应用案例中,通过参数测试获取合理的算法参数取值,采用计算结果分析和求解算法测评验证模型和算法的有效性。 相似文献
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地方高校音乐专业琵琶教学的思考 总被引:1,自引:1,他引:0
琵琶是我国民族乐器中历史最为悠久、极具表现力的弹拨乐器之一。它的音色优美,琵琶演奏技法多且复杂,因而初学门槛高,不容易掌握、精通。在琵琶专业教学中,我们应当明确教学目标,选择好教学内容,改进教学方法,让学生在实践中得到锻炼,努力提高地方院校琵琶教学质量。 相似文献
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影响当代中学生学习及人际关系诸因素调查分析 总被引:4,自引:0,他引:4
该文以对高中学生的学习和人际关系的问卷调查结果为依据,讨论了当代中学生在应试教育模式背景下学习和人际交往存在的一些现象和问题,主要涉及学习与考试成绩的关系,学习动机对学业的影响以及师生关系存在的障碍,同时也提出了一些可行性建议和解决方案. 相似文献