CUMCM2015A_参考答案
2015高教社杯全国大学生数学建模竞赛A题评阅要点[说明]本要点仅供参考，各赛区评阅组应根据对题目的理解及学生的解答，自主地进行评阅。
本题要求根据视频中物体的太阳影子，建立数学模型确定视频拍摄地点和日期。主要考察学生关于空间几何问题的建模能力以及非线性优化问题的求解能力，对求解精度具有一定的要求。
评阅时应注意：“北京时间”与“北京当地时间”的不同，经度与时间的关系，日期关于春分、秋分、冬至、夏至的近似对称性等。大气折射会导致太阳高度角产生一定偏转，所以考虑大气折射情形的模型更佳。
对能够自行构造数据进行模型检验的论文，应给予较好的评价。
问题1
在已知视频拍摄时间及地点的条件下求影子的数学模型，并分析长度关于日期、时间、经纬度等参数的变化规律。有较多的参考文献给出这一问题的模型，若直接采用文献中的模型，需指明出处。
问题2
在已知物体影子顶点真实坐标及拍摄日期与北京时间的条件下，根据问题1得到的影子长度变化模型，反解出纬度及当地时间，根据当地时间和北京时间之间的关系确定经度。附件1的位置是(109.5°E, 18.3°N)。
评阅时应以模型和方法为主，结果仅作为参考。要尽可能使用所给数据的全部信息。
问题3
与问题2相比，问题3中拍摄日期未知，反演难度有所增加，同时使用长度和角度信息反演效果更好。附件2的位置是(79.75°E, 39.52°N)，日期是7月20日；附件3的位置是(110.25°E, 29.39°N)，日期是1月20日。
由于日期相近的影子长度和角度变化较小，导致参数反演问题的近似解较多。可以将日期、经纬度一定范围内的结果都认为是近似正确的。
评阅时应以模型和方法为主，结果仅作为参考。
问题4
建立影子顶点大地坐标与视频坐标之间的关系，然后反演模型中的参数。由于反演参数的增加，以及视频数据提取时产生的误差，导致模型求解精度下降、确定拍摄地点的难度增加。评阅时，主要关注模型是否合理、正确。
c语言试题及答案
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泛读教程第一册 Unit 4 Food
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C语言试题选择题及答案
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新世纪大学英语综合教程1课后答案(全)
2. (1) obtain (2) confident (3) communicate (4) advantage (5) relevant (6) helpful (7) extreme (8) enjoyable (9) means (10) process (11) particularly (12) characters (13) astonished (14) apparently 3. (1) fond of (2) is…related to (3) according to (4) To a certain degree (5) vice versa (6) no doubt (7) rid… of (8) cleare d up (9) or else (10) at all costs (11) sure enough (12) let alone (13) similar to (14) It’s no use (15) in my opinion (16) was worth (II)Increasing Your Word Power 1. (1) c (2) d (3) b (4) b (5) b (6) d 2. (1) highly/very (2) quite/very (3) quite/very/increasingly (4) quite/simply/very 3. 4.No Mistake especial→ especially
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第二章习题及解答
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C B A C B A F ??= A B AB =A B CD AB F +=X X B X A F += 图3 四、图4中G 1为TTL 三态门，G 2为TTL 与非门，万用表的内阻20k Ω/V ，量程5V 。当 C=1或C=0以及S 通或断等不同情况下，U 01和U 02的电位各是多少？ 图4 五、由CMOS 传输门和反相器构成的电路如图5（a ）所示，试画出在图5（b ）波形作用下的输出u o 的波形（u i1=10V u i2=5V ） t t 图5（a ） (b) C S 通S 断11U O1=U O2=U O1=U O2= 00 U O1=U O2= U O1=U O2= U O2
新世纪阅读教程1完整答案
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