2015年美国数学建模竞赛第二次模拟赛题
全国大学生数学建模2015年国二a题
2015高教社杯全国大学生数学建模竞赛承诺书我们仔细阅读了中国大学生数学建模竞赛的竞赛规则.我们完全明白,在竞赛开始后参赛队员不能以任何方式(包括电话、电子邮件、网上咨询等)与队外的任何人(包括指导教师)研究、讨论与赛题有关的问题。
我们知道,抄袭别人的成果是违反竞赛规则的, 如果引用别人的成果或其他公开的资料(包括网上查到的资料),必须按照规定的参考文献的表述方式在正文引用处和参考文献中明确列出。
我们郑重承诺,严格遵守竞赛规则,以保证竞赛的公正、公平性。
如有违反竞赛规则的行为,我们将受到严肃处理。
我们授权全国大学生数学建模竞赛组委会,可将我们的论文以任何形式进行公开展示(包括进行网上公示,在书籍、期刊和其他媒体进行正式或非正式发表等)。
我们参赛选择的题号是(从A/B/C/D中选择一项填写): A我们的参赛报名号为(如果赛区设置报名号的话):所属学校(请填写完整的全名):参赛队员(打印并签名) :1.2.3.指导教师或指导教师组负责人(打印并签名):日期:年月日赛区评阅编号(由赛区组委会评阅前进行编号):编号专用页赛区评阅编号(由赛区组委会评阅前进行编号):全国统一编号(由赛区组委会送交全国前编号):全国评阅编号(由全国组委会评阅前进行编号):太阳影子定位摘要本文研究了太阳影子定位问题,基于天球坐标系相关知识、球面几何理论以及相似度理论,对不同情况下的数据,建立了相应的数学模型并得到了最优的匹配地点与日期。
问题1中,利用球面三角形余弦定理给出了太阳高度角公式,并建立了影子长度变化的数学模型,定性的分析了影子长度关于时角、当地纬度以及赤纬角的变化规律:(1). 时角的绝对值越大,影子长度越大;(2). 在同一经度上(即时角一定),当地纬度与此时的太阳赤纬之差越大,影子长度越大;(3). 在同一纬度不同经度上,当地经度和此时太阳直射点所在的经度之差越大,影子长度越大。
用所建的模型,得到了2015年10月22日北京时间9:00-15:00之间天安门广场3米高的直杆的太阳影子长度的变化曲线。
历届美国数学建模竞赛赛题(汉语版)
历届美国数学建模竞赛赛题, 1985-2006AMCM1985问题-A 动物群体的管理AMCM1985问题-B 战购物资储备的管理AMCM1986问题-A 水道测量数据AMCM1986问题-B 应急设施的位置AMCM1987问题-A 盐的存贮AMCM1987问题-B 停车场AMCM1988问题-A 确定毒品走私船的位置AMCM1988问题-B 两辆铁路平板车的装货问题AMCM1989问题-A 蠓的分类AMCM1989问题-B 飞机排队AMCM1990问题-A 药物在脑内的分布AMCM1990问题-B 扫雪问题AMCM1991问题-A 估计水塔的水流量AMCM1992问题-A 空中交通控制雷达的功率问题AMCM1992问题-B 应急电力修复系统的修复计划AMCM1993问题-A 加速餐厅剩菜堆肥的生成AMCM1993问题-B 倒煤台的操作方案AMCM1994问题-A 住宅的保温AMCM1994问题-B 计算机网络的最短传输时间AMCM1995问题-A 单一螺旋线AMCM1995问题-B A1uacha Balaclava学院AMCM1996问题-A 噪音场中潜艇的探测AMCM1996问题-B 竞赛评判问题AMCM1997问题-A Velociraptor(疾走龙属)问题AMCM1997问题-B为取得富有成果的讨论怎样搭配与会成员AMCM1998问题-A 磁共振成像扫描仪AMCM1998问题-B 成绩给分的通胀AMCM1999问题-A 大碰撞AMCM1999问题-B “非法”聚会AMCM1999问题- C 大地污染AMCM2000问题-A空间交通管制AMCM2000问题-B: 无线电信道分配AMCM2000问题-C:大象群落的兴衰AMCM2001问题- A: 选择自行车车轮AMCM2001问题-B:逃避飓风怒吼(一场恶风…)AMCM2001问题-C我们的水系-不确定的前景AMCM2002问题-A风和喷水池AMCM2002问题-B航空公司超员订票AMCM2002问题-C蜥蜴问题AMCM2003问题-A: 特技演员AMCM2003问题-C航空行李的扫描对策AMCM2004问题-A:指纹是独一无二的吗?AMCM2004问题-B:更快的快通系统AMCM2004问题-C:安全与否?AMCM2005问题-A:.水灾计划AMCM2005问题-B:TollboothsAMCM2005问题-C:.Nonrenewable ResourcesAMCM2006问题-A:用于灌溉的自动洒水器的安置和移动调度AMCM2006问题-B:通过机场的轮椅AMCM2006问题-C:在与HIV/爱滋病的战斗中的交易AMCM85问题-A 动物群体的管理在一个资源有限,即有限的食物、空间、水等等的环境里发现天然存在的动物群体。
2015美国大学生数学建模竞赛D题
1.2 Our work
We tackle four main sub problems: Factors affecting the evaluation of sustainable development of a country are analyzed based on the theory of sustainable development. Develop a model for the sustainability of a country. This model should provide a measure to distinguish more sustainable countries and policies from less sustainable ones. Choose from forty-eight poorest countries LDC country, according to the model of a task1 has been established for the selected countries to create a more sustainable development plan in the next 20 years in the development process, so that the country toward a more sustainable future. Evaluate the effect our 20-year sustainability plan has on our country’s sustainability measure created in Task 1. And predicted under the evaluation system to implement our plan will happen the change over the next 20 years. According to the selected country, we should consider the environmental factors, Climate change, development aid, foreign investment, natural disasters, and the instability of the regime, etc. We determine which project or policy for the sustainable development measures of the state will have the greatest effect. Write a report to explain the established model, including sustainable development, sustainable development plans, according to the model and the national environmental situation, analysis the effect of the plan. For the ICM provides a sustainable development of intervention strategy about investment in LDC countries.
美赛习题答案
美赛习题答案美赛习题答案在数学建模领域,美国大学生数学建模竞赛(MCM)是一项备受关注的赛事。
每年,来自全球各地的大学生们都会参与其中,挑战各种实际问题并提出解决方案。
这项竞赛不仅考察了参赛者的数学水平,更重要的是培养了他们的团队合作和创新思维能力。
本文将探讨一些典型的美赛习题,并给出相应的解答。
第一题是关于城市交通流量的问题。
题目给出了一个城市的道路网络图,要求我们计算出每条道路的平均交通量。
首先,我们可以通过收集实际交通数据来估计每条道路上的车辆数量。
然后,根据道路的长度和车辆数量,我们可以计算出每条道路的平均交通量。
最后,将结果绘制成热力图,可以清晰地显示出城市交通的拥堵情况。
第二题是关于电力系统的问题。
题目给出了一个电力系统的拓扑结构图,要求我们设计一种最优的电力传输方案,以最大化系统的可靠性和效率。
首先,我们可以使用图论的方法对电力系统进行建模,并计算出各个节点之间的电力传输路径。
然后,根据节点之间的电力传输损耗和供电能力,我们可以通过线性规划等数学方法得到最优的电力传输方案。
最后,我们可以通过模拟实验来验证我们的方案,并对其进行优化。
第三题是关于航空公司的问题。
题目给出了一家航空公司的航班数据,要求我们设计一种最优的航班调度方案,以最大化公司的利润和乘客满意度。
首先,我们可以使用图论的方法对航班网络进行建模,并计算出各个航班之间的飞行时间和成本。
然后,根据乘客的需求和航班的运营成本,我们可以通过线性规划等数学方法得到最优的航班调度方案。
最后,我们可以通过模拟实验来验证我们的方案,并对其进行优化。
以上只是美赛习题中的几个例子,实际上还有许多其他有趣的问题,涉及到经济、环境、医疗等领域。
解决这些问题需要我们具备扎实的数学基础和创新的思维能力。
在解题过程中,我们需要灵活运用数学模型和工具,结合实际情况进行分析和判断。
同时,团队合作也是解决问题的关键,每个人都应发挥自己的优势,共同努力达到最佳的解决方案。
2015建模竞赛模拟题目三
2015数学建模竞赛模拟题目(请阅读“数学建模竞赛论文格式规范”)好奇号火星着陆器——下降段燃料最优轨道设计与控制策略自从航天时代开始到现在,人类使用空间探测器对火星探测的脚步从未停止,已经取得了丰硕的成果。
从前苏联最早于1962 年11 月1 日发射首次成功接近火星飞行的“火星1 号”探测器,到1975年美国发射的首次成功软着陆的“海盗号”(Viking)系列探测器,至今已有超过30 个探测器到达过火星并反馈了大量的观测数据,使得火星成为除地球以外人类了解最多的行星。
特别是随着近年来探索火星任务的针对性逐渐增强,定点精确着陆的必要性日益提升,从“火星探路者”(Mars Pathfinder,1996)的150km 着陆精度开始,到“火星探测漫游者”(Mars Exploration Rover,2003)时已达35km,刚刚成功着陆的“火星科学实验室”(Mars Science Laboratory, 2011)已经实现了10km 量级的着陆精度。
而在不远的未来,为了实现对某些危险地区的探测,着陆精度的需求还会持续提升,这给火星着陆系统的设计带来了新一轮的机遇和挑战。
从火星着陆器脱离绕飞轨道开始,一般来说,需要经过进入、下降和着陆(Entry,Descent,Landing,简记EDL)几个阶段最终到达火星表面,其中进入段和下降段的合理规划和设计是完成精确着陆的必要保障。
而在降落的最后一个阶段,即从开启反作用推力器进行有效减速到着陆器成功降落到期望着陆点这一过程称为动力下降段,该阶段只持续仅仅几分钟,但却是决定着陆任务成败的最重要阶段之一,如果下降过程不能有效减速或避开障碍,整个探测任务将前功尽弃。
根据上述的基本要求,请你们对着陆器动力下降段建立数学模型解决下面的问题:(1)考虑各种约束的火星探测器的燃料最优精确着陆问题转化为考虑线性约束和二阶锥约束的优化问题(附)。
(2)计算着陆器最优着陆轨迹,并对其特性进行了细致的分析。
2015年美国(国际)大学生数学建模竞赛
比赛时间:美国东部时间:2015年2月5日(星期四)下午8点-2月9日下午8点(共4天)北京时间:2015年2月6日(星期五)上午9点-2月10日上午9点农历:十二月十八~十二月廿二重要说明:●COMAP是所有的规则和政策的最后仲裁者,对不遵循竞赛规则和程序的任何队伍,拥有唯一的自由裁量权,取消参赛资格或拒绝登记。
●评委、竞赛组织者、以及UMAP杂志的编辑拥有最终裁定权。
●如果参赛队伍违反竞赛规则,其指导老师一年内将不能指导其他团队,其所在参赛单位将被处以一年的察看处理。
●如果同一机构第二次被抓到违反规则的队伍,该学校将至少不被允许参加下一年度的赛事。
●以下所有时间都是美国东部时间EST(北京时间比美国东部时间早13个小时)●递交参赛论文后,意味参赛者同意以下条款:⏹论文提交后,出版权归COMAP, Inc所有;⏹COMAP可以使用,编辑,引用和出版论文,用于宣传或任何其他目的,包括在线展示,出版电子版,在UMAP杂志刊登或其他方式,并且没有任何形式的补偿;⏹COMAP可以在没有进一步的通知,许可,或补偿的情形下,使用这次比赛相关材料,团队成员、指导老师的名字,以及和他们的背景资料。
●递交参赛论文后,意味参赛者作出以下承诺:⏹论文中出现的所有的图像,数据,照片,图表,图画,如果未注明,都是由参赛者创建;如果引用其它资源,都在参考文献中列出,并在引用的具体位置标注来源。
⏹不论是直接,还是转述方式的文字引用,都在参考文献中列出,并在引用的具体位置标注来源;直接的文字引用使用引号标注。
比赛之前注册报名1.报名截至时间:2015年2月5日下午2:00 EST。
截止日期后,注册系统将自动关闭,不再接受任何新的注册,没有例外。
2.每支参赛队伍都必须有一位来自参赛机构(institute)的教师担任导师(faculty advisor),不允许学生担任导师。
由指导老师负责为其指导队伍注册报名,每位指导老师可注册的队伍数目没有限制。
股市分析数学建模
数学建模第二次模拟赛题摘要针对于当前我国股市形势严峻这一情形,我们对国内股票市场的情况进行分析,使得我们能过更好地了解股市的风险程度,进而更好的增强抵抗能力并经得起利益的诱惑。
针对问题一:通过我们详细的查找资料,我们发现市盈率=每股股票价格/每股股票的收益,我们而市盈率以及股票的收益都有固定的值,这样我们就可以知道股票的内在价值了。
同时股票内在价值还有一些其他的模型算法,如:现金流贴现模型(DMM模型)、内部收益率模型(IRR模型)、零增长模型、不变增长模型等。
对于此题我们采用现金流贴现模型来计算股票的内在价值。
针对问题二:我们通过研究中国联通(SH600050)股票的发展走向来验证股票价格与股票内在价值之间的关联,用EXCEL软件作图进行分析比较,发现并不像经典理论所表达的那样“股市中股票价格是围绕股票内在价值上下波动的”。
针对问题三:关于政府救市的言论和措施,一开始没有起效果,主要是因为当时政府当时没有进行大规模的救市,政府在实行政策失误,以便聚集力量等待时机正确果断、准确、强力地出击救市,我们会给出数据分析来验证这一点。
针对问题四:政府救市是为了让股市稳定,让股市走向一个健康发展的道路是毋庸置疑的。
针对问题五:通过我们对历史数据的分析,我们发现当前股票还没调到位,其最有可能调到2700—2800左右。
针对问题六:对于当前的股票,我们发现股市有风险,入市须谨慎。
关键词:股票内在价值零增长模型不变增长模型 excel作图 MATLAB预测股市一、问题重述针对凶险的股市,对其风险程度的了解能更好的使我们增强抵抗能力和经得起其利益的诱惑。
股市里大家熟悉一个叫李大霄的,他在4月8号就说股市在4000点是地球顶,4月21号为止三遍说到顶。
其依据是:当前43%的股票市盈率已经超过100倍,50%的股票超过83%,70%的股票超过51倍,比较严重的特别是创业板已经整体接近100倍,风险比大盘6124时更甚。
2015美国大学生数模竞赛C题翻译
1. ICM aims to identify the risk of churn in its early stages, as it is cheaper to gain the loyalty of anemployee early in their carreer rather than have to improve the culture once it has soured. It is more productive to have a motivated workforce from the start rather than having to provide incentives to prevent people from leaving.ICM旨在识别生产处于早期阶段的风险,因为它是便宜的忠诚员工在他们的事业上,而不是改善早期文化一旦恶化。
是更有生产力从一开始就积极的劳动力而不必提供激励措施阻止人们离开。
2.A worker is more likely to churn if he or she was connected to other former employees who have churned. Thus churn seems to diffuse from employee to employee, so identifying those that are likely to churn is valuable information to prevent further churning.一个工人更有可能生产如果他或她与其他前员工有搅拌。
因此从员工流失似乎弥漫员工,因此识别那些可能产生有价值的信息防止进一步的生产。
3.One HR issue is matching employees to the right position such that their knowledge and abilities can be maximized. Currently each employee gets an annual evaluation based on performance as judged by the supervisor. These ratings are currently not used by the HR office.一个人力资源问题是匹配到正确的位置,这样员工知识和能力可以最大化。
历届美国数学建模竞赛赛题
? 对正常组织或器官的整个体积照射要剂量总和最小
对指定的正常组织点的剂量要限制在忍耐剂量以下?
使关键体积所需的最大剂量达到最小?
在Gamma单元治疗方案中,有以下限制:
禁止“shot”伸展到目标以外?
禁止“shot”交迭(避免热点)?
? 用有效的剂量覆盖尽可能多的目标体积,但至少90%目标体积要被“shot”覆盖
你的任务是设计一个算法,随着风力条件的变化,运用风速计给出的数据来调整由喷泉射出的水流。
AMCM2002问题-B航空公司超员订票
你备好行装准备去旅行,访问New York城的一位挚友。在检票处登记之后,航空公司职员告诉说,你的航班已经超员订票。乘客们应当马上登记以便确定他们是否还有一个座位。
任务1. 提供一个给出风速的表格,在这种速度下实体后轮所需要的体能少于辐条后轮。这个表格应当包括相应于从百分之零到百分之十增量为百分之一的不同公路陡度的风速。(公路陡度定义为一座山丘的总升高除以公路长度。如果把山丘看作一个三角形,它的陡度是指山脚处倾角的正弦。)一位骑手以初始速度45kph从山脚出发,他的减速度与公路陡度成正比。对于百分之五的陡度,骑上100米车速要下降8kph左右。
2005A.水灾计划
南卡罗来纳州中部的磨累河是由北部的一个巨大水坝形成的,这是在1930年为了发电而修建的,模拟一起洪水淹没下游的事件,这起事件是由于一次灾难性的地震损毁了水坝造成的。
两个问题:
Rawls Creek是水坝下游流入Saluda河的一条终年流动的河流,则当水坝损毁后在Rawls Creek将会出现多大的洪流,洪水的波及面将有多大?
AMCM2002问题-A风和喷水池
在一个楼群环绕的宽阔的露天广场上,装饰喷泉把水喷向高空。刮风的日子,风把水花从喷泉吹向过路行人。喷泉射出的水流受到一个与风速计(用于测量风的速度和方向)相连的机械装置控制,前者安装在一幢邻近楼房的顶上。这个控制的实际目标,是要为行人在赏心悦目的景象和淋水浸湿之间提供可以接受的平衡:风刮得越猛,水量和喷射高度就越低,从而较少的水花落在水池范围以外。
2015年美赛数学建模题目
2015 Contest ProblemsMCM PROBLEMSPROBLEM A: Eradicating EbolaThe world medical association has announced that their new medication could stop Ebola and cure patients whose disease is not advanced. Build a realistic, sensible, and useful model that considers not only the spread of the disease, the quantity of the medicine needed, possible feasible delivery systems, locations of delivery, speed of manufacturing of the vaccine or drug, but also any other critical factors your team considers necessary as part of the model to optimize the eradication of Ebola, or at least its current strain. In addition to your modeling approach for the contest, prepare a 1-2 page non-technical letter for the world medical association to use in their announcement.PROBLEM B: Searching for a lost planeRecall the lost Malaysian flight MH370. Build a generic mathematical model that could assist "searchers" in planning a useful search for a lost plane feared to have crashed in open water such as the Atlantic, Pacific, Indian, Southern, or Arctic Ocean while flying from Point A to Point B. Assume that there are no signals from the downed plane. Your model should recognize that there are many different types of planes for which we might be searching and that there are many different types of search planes, often using different electronics or sensors. Additionally, prepare a 1-2 page non-technical paper for the airlines to use in their press conferences concerning their plan for future searches.ICM PROBLEMSPROBLEM C: Managing Human Capital in OrganizationsClick the title below to download a PDF of the 2015 ICM Problem C.Your ICM submission should consist of a 1 page Summary Sheet and your solution cannot exceed 20 pages for a maximum of 21 pages.Managing Human Capital in OrganizationsPROBLEM D: Is it sustainable?Click the title below to download a PDF of the 2015 ICM Problem D.Your ICM submission should consist of a 1 page Summary Sheet and your solution cannot exceed 20 pages for a maximum of 21 pages.Is it sustainable?。
2015数模2(含详细解答)
2015年初中毕业生数学考试卷考生须知:1. 全卷共4页,有3大题,24小题. 满分为120分.考试时间120分钟.2. 本卷答案必须做在答题纸的对应位置上,做在试题卷上无效.3. 请考生将姓名、准考证号填写在答题纸对应位置上,并认真核准条形码姓名、准考证号.4. 作图时,可先使用2B 铅笔,确定后必须使用0.5毫米及以上的黑色签字笔涂黑.5. 本次考试不能使用计算器.参考公式:二次函数y =ax 2+bx +c (a ≠0)图象的顶点坐标是)442(2ab ac a b --,. 卷 Ⅰ说明:本卷共有1大题,10小题,每小题3分,共30分.一、选择题(请选出各题中一个符合题意的正确选项,不选、多选、错选,均不给分)1.2015-的相反数是 A 2015 B 20151 C 20151- D 2015-2.下列运算正确的是 A .6a -5a=1 B .(a 2)3=a 5C .a 6÷a 3=a 2D .a 2·a 3=a 53.钓鱼岛自古以来就是中国的固有领土,在“百度”搜索引擎中输入“钓鱼岛最新消息”,能搜索到与之相关的结果个数约为4640000,这个数用科学记数法表示为A . 464×104B .46.4×106C .4.64×106D .0.464×10745. 如果分式12-x 与33+x 的值相等,则x 的值是A .9B .7C .5D .36.一个正多边形的每个内角都为140°,那么这个正多边形的边数为 A. 11 B.10 C.9 D.8 7.若x >y ,则下列式子中错误的是 A .x ﹣3>y ﹣3B .>C .x +3>y +3D .﹣3x >﹣3y8.已知等腰三角形的一边长为4,另一边长为8,则这个等腰三角形的周长为 A.12 B.20 C. 16 D. 20或16 9. 矩形具有而菱形不具有的性质是A .两组对边分别平行B .对角线相等C .对角线互相平分D .两组对角分别相等10.如图,D 为△ABC 内部一点,E 、F 两点分别在AB 、BC 上,且四边形DEBF 为矩形,直线CD 交AB 于G 点.若CF =6,BF =9,AG =8,则△ADC 的面积为 A .16 B .24C .36D .54正面A C B D卷 Ⅱ二、填空题(本题有6小题,每小题4分,共24分) 11.因式分解:x xy 42-= ▲ .12.有8只型号相同的杯子,其中一等品5只,二等品2只和三等品1只,从中随机抽取1 只杯子,恰好是一等品的概率是 ▲ .13.甲种电影票每张20元,乙种电影票每张15元.若购买甲、乙两种电影票共40张,恰好用去700元,则甲种电影票买了 张.14则关于这若干户家庭的月用水量,中位数是 ▲ 吨,月平均用水 ▲ 吨. 15.定义:我们把二次函数2y ax=+ 友好函数 16.如图,A 是反比例函数ky x=做CD ⊥x 轴,垂足为点D ,延长与点B 的纵坐标之比为 ▲ ;(2三、解答题(本题有8小题,第17~ 第20、21题每题8分,第22、2317.计算: 2︒45sin --+-28(318.先化简后求值:ab b b a a 22422-+-,其中1000=a ,15=b19.如图,AB 是半圆O 的直径,C 、D 是半圆O 上的两点, 且OD ∥BC ,OD 与AC 交于点E . (1)若∠B =70°,求∠CAB 的度数; (2)若AC =8,OE =3,求AB 的长.20.某中学为合理安排体育活动,在全校喜欢乒乓球、排球、羽毛球、足球、篮球五种球类运动的1000名学生中,随机抽取了若干名学生进行调查,了解学生最喜爱的一种球类运动,每人只能在这五种球类运动中选择一种,调查结果统计如下:By)(元)16001400600解答下列问题: (1)求a 与b 的值;(2)试估计上述1000名学生中最喜欢羽毛球运动的人数.21.某销售公司推销一种产品,设x (件)是推销产品的数量,y (元)是付给推销员的月报酬.公司付给推销员的月报酬的两种方案如图所示,推销员可以任选一种与公司签订合同.看图解答下列问题: (1)求每种付酬方案y 关于x 的函数表达式; (2)当选择方案一所得报酬高于选择方案二所 得报酬时,求x 的取值范围.22.2015年4月19日,义乌市国际马拉松在梅湖体育场胜利召开.体育场主席台侧面如图,若顶棚顶端D 与看台底端A 连线和地面垂直,测得看台AC 的长为13.5米, 30=∠BAC , 45=∠ACD . (1)求看台高BC 的长(2)求顶棚顶端D 到地面的距离AD 的长.(取7.13=)23.在△ABC 中,∠ACB =45°,点D 为射线BC 上一动点(与点B 、C 不重合),连接AD ,以AD 为一边在AD 右侧作正方形ADEF .(1)如果AB =AC ,如图1,且点D 在线段BC 上运动,判断∠BAD ▲ ∠CAF (填“=”或“≠”),并证明:CF ⊥BD ;(2)如果AB ≠AC ,且点D 在线段BC 的延长线上运动,请在图②中画出相应的示意图, 此时(1)中的结论是否成立?请说明理由;(温馨提示:作图时,先使用2B 铅笔,再 使用0.5毫米及以上的黑色签字笔涂黑).(3)设正方形ADEF 的边DE 所在直线与直线CF 相交于点P ,若AC =42,CD =2,求线段CP 的长.AE FA24.如图,四边形OABC 是平行四边形,点)0,2(-A ,点)32,0(B ,动点P 从点O 出发以每秒3个单位长度的速度沿射线OB 方向匀速运动,同时动点Q 从点B 出发以每秒2个单位长度的速度沿射线BA 方向匀速运动,连结CP ,CQ ,设运动时间为t 秒. (1)求点C 的坐标和OCB ∠的度数;(2)请用含t 的代数式表示动点P 和动点Q 的坐标; (3)①当BCQ BCP ∠=∠时,求t 的值;②当30≤∠-∠BCP BCQ 时, 求t 的取值范围(只要写出直接答案).参考答案及评分标准一、选择题DDCAA CDBBB 二、填空题 11.)2)(2(+-y y x 12.8513.20 14.4.5;4.6 (一个对二分,二个对三分) 15.略 (二个对才能得三分 ) 16.(1) 1:3 (一分) (2) 9(二分) 三、解答题17.原式=1222222-+-⨯…(每个一分)4分=21- …………6分18.原式=b a b b a a ---22422………………2分=ba b a --2422=b a +2………………4分代入得,原式=2015………………6分 19.(1)20=∠CAB ………(看答案)3分 (2)10=AB ……………………6分 20.(1)30=a ……………………3分24=b ……………………6分(2)300人……………………8分 21.(1)方案一:x y 40=………………2分 方案二60020+=x y ……………………4分(2)6002040+>x x ……………6分 ∴30>x ……………………8分 22.(1)75.6=BC ……………………5分 (2)过点D 作AC DE ⊥于E∵ 45=∠ACD , 30=∠BAC∴ 45=∠CDE , 60=∠EAD 设x AE = ∴x DE CE 3==∴5.137.23==+=x x x AC ∴5=x ∴AD =10米 ……………10分B23.(1)CF ⊥BD ……………1分证明:∵∠ACB =45°,AB =AC ∴∠ABC =∠ACB =45°,∴∠BAC =90° ∵四边形ADEF 是正方形,∴AD =AF ,∠DAF =90° ∵∠BAD =∠BAC -∠DAC ,∠CAF =∠DAF -∠DAC∴∠BAD =∠CAF ,∴△BAD ≌△CAF ∴∠ACF =∠ABD =45°,∴∠ACF +∠ACB =90° ∴CF ⊥BD ……………3分 (2)如图所示,(1)中的结论仍然成立 证明:过A 作AG ⊥AC 交BC 于G∵∠ACB =45°,∴∠AGC =45°∴∠GAC =90°,AG =AC ∵四边形ADEF 是正方形,∴AD =AF ,∠DAF =90° ∵∠GAD =∠GAC +∠DAC ,∠CAF =∠DAF +∠DAC∴∠GAD =∠CAF ,∴△GAD ≌△CAFGB∴∠ACF =∠AGD =45°,∴∠ACF +∠ACB =90° ∴CF ⊥BD ……………6分 (3)作AH ⊥BD 于H ∵∠ACB =45°,∴△AHC 是等腰直角三角形 ∴AH =HC =22AC =22×42=4∵AH ⊥BD ,CF ⊥BD ,∠ADE =90° ∴△ADH ∽△DPC ,∴CPCD=DHAH……………8分 当点D 在线段BC 上时DH =HC -CD =4-2=2 ∴CP2=24,∴CP =1……………9分 当点D 在线段BC 的延长线上时 DH =HC +CD =4+2=6 ∴CP2=64,∴CP =3……………10分 24.(1))32,2(C , 60=∠OCB ……………………2分(2))3,0(t P ,)332,(t t Q --……………………6分(3)①当点P 在线段OB 上时: 过点Q 作OB QD ⊥于D ∴PQD ∆∽PCB ∆ ∴BPDPBC DQ =∴tt t 33232322--=∴15-=t ……………………8分当点P 在线段OB 的延长线上时: 过点Q 作OB QD ⊥于D ,作P 关于BC 的对称点'P ∵BCQ BCP ∠=∠ ∴点'P 在CQ 上 ∴QD P '∆∽CB P '∆∴''BP DP BC DQ = ∴323322-=t t ∴15+=t ……………………9分②697174+≤≤t 或6735+≥t …12分。
2015 AMC10A美国数学竞赛试题
What is the value ofProblem2A box contains a collection of triangular and square tiles.There are tiles in the box, containing edges total.How many square tiles are there in the box?Problem3Ann made a3-step staircase using18toothpicks.How many toothpicks does she need to add to complete a5-step staircase?Problem4Pablo,Sofia,and Mia got some candy eggs at a party.Pablo had three times as many eggs as Sofia,and Sofia had twice as many eggs as Mia.Pablo decides to give some of his eggs to Sofia and Mia so that all three will have the same number of eggs.What fraction of his eggs should Pablo give to Sofia?Problem5Mr.Patrick teaches math to students.He was grading tests and found that when hegraded everyone's test except Payton's,the average grade for the class was.After he graded Payton's test,the test average became.What was Payton's score on thetest?The sum of two positive numbers is times their difference.What is the ratio of thelarger number to the smaller number?Problem7How many terms are there in the arithmetic sequence,,,...,,?Problem8Two years ago Pete was three times as old as his cousin Claire.Two years before that, Pete was four times as old as Claire.In how many years will the ratio of their ages be :?Problem9Two right circular cylinders have the same volume.The radius of the second cylinderis more than the radius of the first.What is the relationship between the heights of the two cylinders?Problem10How many rearrangements of are there in which no two adjacent letters are alsoadjacent letters in the alphabet?For example,no such rearrangements could include either or.The ratio of the length to the width of a rectangle is:.If the rectangle hasdiagonal of length,then the area may be expressed as for some constant.What is?Problem12Points and are distinct points on the graph of.What is?Problem13Claudia has12coins,each of which is a5-cent coin or a10-cent coin.There are exactly17different values that can be obtained as combinations of one or more of her coins.How many10-cent coins does Claudia have?Problem14Problem15Consider the set of all fractions where and are relatively prime positive integers. How many of these fractions have the property that if both numerator anddenominator are increased by,the value of the fraction is increased by?Problem16If,and,what is the value of?Problem17A line that passes through the origin intersects both the line and the line.The three lines create an equilateral triangle.What is the perimeter of the triangle?Problem18Hexadecimal(base-16)numbers are written using numeric digits through as well as the letters through to represent through.Among the firstpositive integers,there are whose hexadecimal representation contains onlynumeric digits.What is the sum of the digits of?Problem19The isosceles right triangle has right angle at and area.The raystrisecting intersect at and.What is the area of?Problem20A rectangle has area and perimeter,where and are positive integers.Which of the following numbers cannot equal?Problem21Tetrahedron has,,,,,and.What is the volume of the tetrahedron?Problem22Eight people are sitting around a circular table,each holding a fair coin.All eight people flip their coins and those who flip heads stand while those who flip tails remain seated.What is the probability that no two adjacent people will stand?Problem23The zeros of the function are integers.What is the sum of the possible values of?Problem24For some positive integers,there is a quadrilateral with positive integerside lengths,perimeter,right angles at and,,and.Howmany different values of are possible?Problem25Let be a square of side length.Two points are chosen independently at random onthe sides of.The probability that the straight-line distance between the points is atleast is,where,,and are positive integers with.Whatis?。
15年数学建模B题
2015美国数学竞赛AMC12试题及答案
2015美国数学竞赛AMC12试题及答案Problem1What is the value ofProblem2Two of the three sides of a triangle are20and15.Which of the following numbers is not a possible perimeter of the triangle?Problem3Mr.Patrick teaches math to15students.He was grading tests and found that when he graded everyone's test except Payton's,the average grade for the class was80.after he graded Payton's test,the class average became81.What was Payton's score on the test?Problem4The sum of two positive numbers is5times their difference.What is the ratio of the larger number to the smaller?Problem5Amelia needs to estimate the quantity,where and are large positiveintegers.She rounds each of the integers so that the calculation will be easier to do mentally.In which of these situations will her answer necessarily be greater than the exact value of?Problem6Two years ago Pete was three times as old as his cousin Claire.Two years before that, Pete was four times as old as Claire.In how many years will the ratio of their ages be ?Problem7Two right circular cylinders have the same volume.The radius of the second cylinderis more than the radius of the first.What is the relationship between the heights of the two cylinders?Problem8The ratio of the length to the width of a rectangle is:.If the rectangle hasdiagonal of length,then the area may be expressed as for some constant.What is?Problem9A box contains2red marbles,2green marbles,and2yellowmarbles.Carol takes2 marbles from the box at random;then Claudia takes2of the remaining marbles at random;and then Cheryl takes the last2marbles.What is the probability that Cheryl gets2marbles of the same color?Problem10Integers and with satisfy.What is?Problem11On a sheet of paper,Isabella draws a circle of radius,a circle of radius,and all possible lines simultaneously tangent to both circles.Isabella notices that she has drawn exactly lines.How many different values of are possible?Problem12The parabolas and intersect the coordinate axes in exactly four points,and these four points are the vertices of a kite of area.What is?Problem13A league with12teams holds a round-robin tournament,with each team playing every other team exactly once.Games either end with one team victorious or else end in a draw.A team scores2points for every game it wins and1point for every game it draws.Which of the following is NOT a true statement about the list of12scores?Problem14What is the value of for which?Problem15What is the minimum number of digits to the right of the decimal point needed toexpress the fraction as a decimal?Problem16Tetrahedron has and .What is the volume of the tetrahedron?Problem17Eight people are sitting around a circular table,each holding a fair coin.All eight people flip their coins and those who flip heads stand while those who flip tails remain seated.What is the probability that no two adjacent people will stand?Problem18The zeros of the function are integers.What is the sum of the possible values of?Problem19For some positive integers,there is a quadrilateral with positive integerside lengths,perimeter,right angles at and,,and.Howmany different values of are possible?Problem20Isosceles triangles and are not congruent but have the same area and the sameperimeter.The sides of have lengths of and,while those of have lengthsof and.Which of the following numbers is closest to?Problem21A circle of radius passes through both foci of,and exactly four points on,the ellipse with equation.The set of all possible values of is an interval. What is?Problem22For each positive integer n,let be the number of sequences of length n consisting solely of the letters and,with no more than three s in a row and nomore than three s in a row.What is the remainder when is divided by12?Problem23Let be a square of side length1.Two points are chosen independently at random onthe sides of.The probability that the straight-line distance between the points is atleast is,where and are positive integers and.Whatis?Problem24Rational numbers and are chosen at random among all rational numbers in the interval that can be written as fractions where and are integers with .What is the probability that is a real number?Problem25A collection of circles in the upper half-plane,all tangent to the-axis,is constructedin layers as yer consists of two circles of radii and that areexternally tangent.For,the circles in are ordered according to their points of tangency with the-axis.For every pair of consecutive circles in this order, a new circle is constructed externally tangent to each of the two circles in the pair.Layer consists of the circles constructed in this way.Let,andfor every circle denote by its radius.What isDIAGRAM NEEDED。
2015年美国数学建模C题(中文)
C题英文翻译管理人力资本的组织建设充满了良好的,有才华的,训练有素的人的组织是成功的关键之一。
但要做到这一点,组织需要做更多的招聘和雇用的最佳人选- 他们还需要留住优秀的人才,让他们适当培训,并放置在适当的位置,并最终瞄准新员工来替换那些离开组织。
个人与组织内发挥独特的作用,无论是正式的和非正式。
因此,个体从一个组织出发离开重要信息和功能组件缺少需要更换。
这是真正的体育团队,商业公司,学校和大学,政府,以及几乎任何正式的团体或组织的人。
通过提高保留和激励,协调培训,并建立良好的团队的人力资源(HR)专家帮助高层领导管理人员。
特别是领导寻求建立一个有效的组织结构,那里的人都分配到适合自己的人才和经验职位,并在高效的通信系统到位,以促进创新的理念,优质的产品(商品或服务)的开发。
人力资源管理的这些人才管理和团队建设等方面的改造许多现代组织。
在一个组织内管理人力资本的流体网络需要了解的人员忠诚于公司,并分组;建立信任在工作场所;和管理的人之间的正式和非正式关系的形成,解散和保留。
当人们前往其他工作或退休所取代,所产生的紊流统称为组织的“流失”。
你的团队已经问过你的人力资源经理制定信息协同制造(ICM)组织的370人之内了解客户流失的框架和模型。
ICM是在竞争激烈的市场,导致相关的有效管理其人力资本的具有挑战性的问题。
人力资源经理希望通过建立一个网络模型映射在组织中的人力资本。
以下是贵公司面临的一些问题:1.ICM目的是找出客户流失的风险,在其早期阶段,因为它是便宜,得到员工的忠诚早在他们carreer,而不是要提高文化一旦恶化。
这是更高效有一个积极进取的队伍从一开始,而不是提供激励措施,以阻止人们离开。
2.一名工人更容易流失,如果他或她被连接到谁搅动了其他前雇员。
因此,客户流失似乎从员工到员工扩散,所以识别那些可能流失是有价值的信息,以防止进一步搅动。
3.一个HR问题是匹配的雇员在正确位置,使得他们的知识和能力可以最大化。
[理学]数学建模第2次模拟赛题
问题B:邮政运输网络中的邮路规划和邮车调度我国的邮政运输网络采用邮区中心局体制,即以邮区中心局作为基本封发单元和网路组织的基本节点,承担着进、出、转口邮件的处理、封发和运输任务,在此基础上组织分层次的邮政网。
邮路是邮政运输网络的基本组成单元,它是指利用各种运输工具按固定班期、规定路线运输邮件,并与沿线有交接频次的邮政局、所交换邮件总包所行驶的路线。
邮路的结构形式有三种:辐射形、环形和混合形。
如图1所示,邮路A为一条环形邮路,邮路B为一条辐射形邮路。
图1邮路示意图(1)辐射形邮路:是指从起点局出发,走直线或曲折线的邮路,其特点是不论用一种或几种运输工具联运,从起点到终点后,仍按照原路线返回出发地点。
因此须在同一条路线上往返两个行程。
这种邮路可以缩短运递时间,加快邮运速度。
但它的联系点较少,需用的运输工具较多,所耗费用较大。
(2)环形邮路:是指邮政运输工具走环形路线的邮路,即运输工具从起点出发单向行驶,绕行一周,经过中途各站,回到出发地点。
它的特点是不走重复路线,联系点较多,运输工具的利用率高,运费也较省。
但是邮件送到最后几个交接点的时间较长。
(3)混合形邮路:是指包含辐射形和环形两种结构形式的邮路。
某地区的邮政局、所分布如图2所示,分为地市中心局(简称地市局)、县级中心局(简称县局)和支局三级机构,该地区的邮政运输网络由区级邮政运输网和县级邮政运输网构成。
区级邮政运输网由从地市局出发并最终返回地市局的区级邮车所行驶的全部邮路构成,县级邮政运输网由从县局出发并最终返回县局的县级邮车所行驶的全部邮路构成。
为使邮政企业实现低成本运营和较高的服务质量,我们需要对该地区的邮政运输网络进行重构,确定合适的邮路规划方案并进行邮车的合理调度。
为了满足邮政的时限要求,必须尽可能地保证各县局、支局在营业时间内收寄的多数邮件能当天运送回地市局进行分拣封发等处理,以及每天到达地市局的多数邮件能当天运送到目的地县局、支局。
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Problem A Warmer Days or Sour Grapes ?The high quality of wines(葡萄酒)produced in the Finger Lakes Region(五指湖区)of upstate (北部)New York is widely known. Proximity(接近)to lakes tempers the climate and makes it more suitable for growing several varieties of premium(独特)grapes: R iesling(雷司令), G ewürztraminer(琼瑶浆),C hardonnay(霞多丽), M erlot(梅洛), P inot Noir(黑比诺), and CabernetF ranc(品丽珠). (There are many more, but we will restrict(限制)the discussion to these six to simplify(简化)the modeling.) Each variety has its own preferred “average temperature” range but is also different in its susceptibility(感受性)to diseases and ability to withstand(抵抗)short periods of unusually cold temperature.As our local climate changes, the relative suitability of these varieties will be changing as well. A forward-looking winery(酒厂)has hired your team to help with the long-term planning. You will need to recommenda) the proportion(比例)of the total vineyard(葡萄园)to be used for growing each of the above six varieties;b) and when should these changes be implemented (实施)(based on observed temperatures and/or current market prices for each type of wine).Naturally, the winery is interested in maximizing its annual profit. But since the latter (后者)is weather-dependent, it might vary a lot year-to-year. You are also asked to evaluate the trade-offs (权衡)between optimizing the expected/average case versus the worst(-realistic-)scenario(情景).Things to keep in mind:Climate modeling is complicated(复杂)and predicting the rate of “global warming” is a hotly debated area. For the purposes of this problem, assume that the annual average temperature in Ithaca(伊萨卡), NY will increase by no more than 4°C by the end of this century.It is not all about the average temperature – a short snap(临时)of sub- zero(零度)temperature in late Ferburay or early March (after the vines already started getting used to warmer weather) is far more damaging than the same low temperature would be in the middle of the winter.It takes at least 3 years for a newly planted vine to start producing grapes suitable for winemaking.Problem B Outlook of Car-to-Car TechSAN FRANCISCO -- After more than a decade of research into car-to-car communications, U.S. auto safety regulators took a step forward today by unveiling their plan for requiring cars to have wireless gear that will enable them to warn drivers of danger.These vehicle-to-vehicle (V2V) transmitters and software could save thousands of lives and prevent hundreds of thousands of crashes each year by providing cars with information they never will be able to gather simply from cameras and sensors. “Safety is our top priority, and V2V technology represents the next great advance in saving lives,” Transportation Secretary Anthony Foxx said in an announcement. “This technology could move us from helping people survive crashes to helping them avoid crashes altogether.”Requirement 1: Present a mathematical model to discuss the reduction of the number of traffic accidents and road fatalities/injuries in San Francisco by V2V technology. Requirement 2: Determine the maximum number of cars in San Francisco due to the V2V technology.Requirement 3: Discuss the benefits of V2V technology to alleviate road congestion. Requirement 4: Provide your recommendation to the government.Prblem C Forest FiresOne major environmental concern is the occurrence of forest fires (also called wildfires), which affect forest preservation, bring economical and ecological damage and endanger human lives. Such phenomenon is due to multiple causes (e.g. human negligence and lightnings). Despite an increasing of state expenses to control this disaster, each year millions of forest hectares (ha) are destroyed all around the world.Fast detection is an important element for successful firefighting. Traditional human surveillance is expensive and affected by subjective factors, there has been an emphasis to develop automatic solutions, such as satellite-based, infrared/smoke scanners and local sensors (e.g. meteorological). Propagation models try to describe the future evolution of the forest fire given an initial scenario and certain input parameters. Modeling the dynamical behavior of fire propagation in a forest is helpful for creating scheme to control and fight fire.Requirement 1 Describe several different metrics that could be used to evaluate the effectiveness of fire detection. Could you combine your metrics to make them even more useful for measuring quality?Requirement 2 Model the dynamical behavior of fire spread in a forest. Requirement 3 Discuss the factors to affect fire occurrence. Which factors are the most critical in causing fires. Build mathematical models to predict the burned area of fires using Meteorological Data.Requirement 4 Give y our suggestion for preventing from forest fire and fighting against it.Problem D Wearable Activity RecognitionThe percentage of EU citizens aged 65 years or over is projected to increase from 17.1% in 2008 to 30.0% in 2060. In particular, the number of 65 years old is projected to rise from 84.6 million to 151.5 million, while the number of people aged 80 or over is projected to almost triple from 21.8 million to 61.4 million (EUROSTAT: New European Population projections 2008–2060). It has been calculated that the purely demographic effect of an ageing population will push up health-care spending by between 1% and 2% of the gross domestic product (GDP) of most member states. At first sight this may not appear to be very much when extended over several decades, but on average it would in fact amount to approximately a 25% increase in spending on health care, as a share of GDP, in the next 50 years (European Economy Commission, 2006). The effective incorporation of technology into health-care systems could therefore be decisive in helping to decrease overall public spending on health. One of these emerging health-care systems is daily living physical activity recognition.Daily living physical activity recognition is currently being applied in chronic disease management (Amft & Troter, 2008; Zwartjes, Heida, van Vugt, Geelen, & Veltink, 2010), rehabilitation systems (Sazonov, Fulk, Sazonova, & Schuckers, 2009) and disease prevention (Sazonov, Fulk, Hill, Schutz, & Browning, 2011; Warren et al., 2010), as well as being a personal indicator to health status (Arcelus et al., 2009). One of the principal subjects of the health related applications being mooted is the monitoring of the elderly. For example, falls represent one of the major risks and obstacles to old people’s independence (Najafi, Aminian, Loew, Blanc, & Robert, 2002; Yu, 2008). This risk is increased when some kind of degenerative disease affects them. Most Alzheimer’s patients, for exa mple, spend a long time every day either sitting or lying down since they would otherwise need continuous vigilance and attention to avoid a fall.The registration of daily events, an important task in anticipating and/or detecting anomalous behavior patterns and a primary step towards carrying out proactive management and personalized treatment, is normally poorly accomplished by patients’ families, healthcare units or auxiliary assistants because of limitations in time and resources. Automatic activity-recognition systems could allow us to conduct a completely detailed monitoring and assessment of the individual, thus significantly reducing current human supervision requirements.Most wearable activity recognition systems assume a predefined sensor deployment that remains unchanged during runtime. However, this assumption does not reflect real-life conditions. During the normal use of such systems, users may place the sensors in a position different from the predefined sensor placement. Also, sensors may move from their original location to a different one, due to a loose attachment. Activity recognition systems trained on activity patterns characteristic of a given sensor deployment may likely fail due to sensor displacements.Your task is as follows.(1) Build models to recognize daily living activities.(2) Explore the effects of sensor displacement induced by both the intentionalmisplacement of sensors and self-placement by the user.(3) Verify your recognition models’ toleranc e to sensor displacement.Data Set Information:The REALDISP (REAListic sensor DISPlacement) dataset has been originally collected to investigate the effects of sensor displacement in the activity recognition process in real-world settings. It builds on the concept of ideal-placement, self-placement and induced- displacement. The ideal and mutual-displacement conditions represent extreme displacement variants and thus could represent boundary conditions for recognition algorithms. In contrast, self-placement reflects a users perception of how sensors could be attached, e.g., in a sports or lifestyle application. The dataset includes a wide range of physical activities (warm up, cool down and fitness exercises), sensor modalities (acceleration, rate of turn, magnetic field and quaternions) and participants (17 subjects). Apart from investigating sensor displacement, the dataset lend itself for benchmarking activity recognition techniques in ideal conditions.Dataset summary:#Activities: 33#Sensors: 9#Subjects: 17#Scenarios: 3ACTIVITY SET:A1: WalkingA2: JoggingA3: RunningA4: Jump upA5: Jump front & backA6: Jump sidewaysA7: Jump leg/arms open/closedA8: Jump ropeA9: Trunk twist (arms outstretched)A10: Trunk twist (elbows bent)A11: Waist bends forwardA12: Waist rotationA13: Waist bends (reach foot with opposite hand)A14: Reach heels backwardsA15: Lateral bend (10_ to the left + 10_ to the right)A16: Lateral bend with arm up (10_ to the left + 10_ to the right)A17: Repetitive forward stretchingA18: Upper trunk and lower body opposite twistA19: Lateral elevation of armsA20: Frontal elevation of armsA21: Frontal hand clapsA22: Frontal crossing of armsA23: Shoulders high-amplitude rotationA24: Shoulders low-amplitude rotationA25: Arms inner rotationA26: Knees (alternating) to the breastA27: Heels (alternating) to the backsideA28: Knees bending (crouching)A29: Knees (alternating) bending forwardA30: Rotation on the kneesA31: RowingA32: Elliptical bikeA33: CyclingSENSOR SETUP:Each sensor provides 3D acceleration (accX,accY,accZ), 3D gyro (gyrX,gyrY,gyrZ), 3D magnetic field orientation (magX,magY,magZ) and 4D quaternions (Q1,Q2,Q3,Q4). The sensors are identified according to the body part on which is placed respectively:。