Loved it . and they want us to come up with another reg ] ular spot for you 很喜欢，他们想要给你一个固定的栏目
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Loved it . and they want us to come up with another reg ular spot for you 很喜欢，他们想要给你一个固定的栏目
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As patients may be asymptomatic at the early stage of disease , and early treatment can minimize further vision loss , so it is important for elders to have reg ular eye examination age - related macular degeneration can result in permanent vision loss ; thus elders should seek medical attention promptly if they notice problems in central vision or color vision 定期的眼睛检查:定期的眼睛检查是发现老年性黄斑点退化的唯一方法，因患者可能没有自觉症状，而及早治疗可防止视力进一步减低，所以定期的眼睛检查对长者尤为重要老年性黄斑点退化是可引致视力永久丧失的眼疾，所以长者如果出现中心视力色觉或其他视力问题，应尽快求医，早作检查。
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In this thesis , studies are focused on as follows : ( 1 ) based on analyzing the general transfer - matrix , the conception of the generalized double layer soil model is proposed , and the transfer - matrix ( r ) of half - infinite elastic mass is introduce - d to the analytic expressions of stress and settlement under the uniform circular , rectangular and strip vertical loads in multi - layered soil ; ( 2 ) according to the analytic expressions of the additional stress and settlement under unifo - rm circular in multi - layered soil , rectangular and strip vertical loads , the programs are develop - ed to resolve and debugged . the results show that the programs are correct ; ( 3 ) through calculating the coefficient of additional stress on the central axis of uniform circ - ular vertical loads , under the corner point of the uniform rectangular vertical loads , and on the central axis of uniform strip vertical loads , and the settlement on the center of uniform circular vertical loads and uniform rectangular loads in double - layered soil , the characters of stress and settlement are discussed ; ( 4 ) a case , as an example , is studied with different calculation methods , such as traditional theory , fem . the results obtained are compared 本文在已有研究成果的基础上进一步开展了以下几方面的研究： ( 1 )在对层状地基传递矩阵法中的总传递矩阵分析的基础上，提出了广义双层地基模型的概念，并把半无限体的传递矩阵r引入到多层地基在圆形垂直均布荷载、矩形垂直均布荷载及条形垂直均布荷载作用下附加应力与沉降的解析式中； ( 2 )根据多层地基在圆形荷载、矩形垂直均布荷载及条形垂直均布荷载作用下附加应力与沉降的解析式，编制了程序，调试通过并验证了其正确性； ( 3 )通过对双层地基圆形垂直均布荷载中心轴线上的附加应力系数和荷载中心沉降，矩形垂直均布荷载角点下的附加应力系数和荷载角点沉降及条形垂直均布荷载中心轴线上的附加应力系数进行的计算，探讨了双层地基中的附加应力与沉降特性； ( 4 )应用本文的层状地基体系理论对一个工程实例进行了计算分析，并与传统的计算方法的计算结果和有限单元方法的计算结果进行了对比分析，结果表明利用层状地基理论计算更能反映地基中附加应力分布的实际情况。
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Abstract : the theory of variable structure control of sing ular nonlinear control systems was considered based on the singular nonlinear systems itself by employing the method of geography , and gives the sufficient condition of existence of variable structure control and approximation theory of real sliding mode . it is shown that sliding condition only guarantee the slow - varying state of real sliding mode approach that of ideal sliding mode but not guarantee the fast - varying state of real sliding mode approach that of ideal sliding mode . the method applied for studying normal nonlinear system can not be used directely to singular nonlinear system 文摘:利用几何方法，从广义非线性系统本身出发，研究了广义非线性控制系统的变结构控制理论，给出了系统存在变结构控制的充分条件及实际滑动模的近似定理.从所得结论可知，滑动条件仅能保证实际滑动模的慢变状态趋近于理想滑动模的慢变状态，而不能保证实际滑动模的快变状态趋近于理想滑动模的快变状态，研究正常非线性系统的方法已不能简单地被利用到广义非线性系统
