2015年 全国研究生数学建模竞赛 C题

C题原文Why people turn to terrorism, and especially suicidal terrorism?What are the major reasons? It’s typically a combination of big issues and little ones, or what some call “push and pull” factors. The bigger issues include alienation, shared anger or outrage (e.g. at some foreign policy), frustration, disillusionment, a sense of victimization by the actions, or in the case of Syria, inactions, of others.The littler issues, the “lures” include the perceived benefits of turning - e.g. adventure, excitement, camaraderie, a sense of belonging,being part of something far bigger etc. The key to understanding is not just to ask why people turn but how they turn, and what strategies recruiters use in that process. Effective recruiters will use whatever tools in their arsenal to pull someone in, whether it is convincing them of their duty to go fight in defense of others,to convincing them that involvement offers them a way out of the humiliation and victimization the recruiter will remind the young person they are otherwise destined to face at home. Radicalization,and how it relates to recruitment (and how we respond to it) is a constantly changing system. Some extreme traits are not as disadvantageous for fitness, as they appear to be for social adaptation or well-being, even when severely disordered subjects are examined.In fact, some traits increase in severity, they become more advantageous for attracting more mates and even producing more offspring.This would characterize these traits as risky shortcuts to fitness,owing less to failures than to the twists and turns made by genes in order to perpetuate themselves. Why someone joins today is different to why someone might have joined even the same group three years ago. The idealism that helps draw someone into terrorism often conflicts with the reality as experienced by the newly minted recruit.Entrapment (in a psychological sense) develops quickly and recruits have to cope with that disillusionment one way or another.You acquiesce to it and move on, maybe by embracing ideological content or seeking comfort in the camaraderie. Or you struggle with and try to conceal it until you can get out. Some terrorists report being disillusioned long before they have been able to disengage from terrorism. They report a sense of suffocation - being unable to leave for fear of retaliation (either by the terrorists or by the State) and being equally afraid of their disillusionment being detected by those close to them in the movement. We need to do a better job of providing “o ff-ramps” not just for people who are on the road to terrorism in the first place, but also to those who have gotten themselves in a jam and want to get out before it’s too late. We need to know their certain psychological characteristics.Consider two questions. First: Who are you? What makes you different from your peers, in terms of the things you buy, the clothes you wear, and the car you drive (or refuse to)? What makes you unique in terms of your basic psychological make-up-the part of you that makes you do the things you do, say the things you say, and feel the things you feel? And the second question: How do you use the internet?Although these questions may seem unrelated, they’re not. Clearly the content of your internet usage can suggest certain psychological characteristics. Spending a lot of late nights playing high stakes internet poker? Chances are you area risk taker. Like to post videos of yourself doing karaoke on YouTube? Clearly an extravert. Choose to play as a opposite gender character in online games? You want to get attention or kinder treatment from other players.But what about the mechanics of your internet usage - how often you email others, chat online, stream media, play game, or multi-task (switch from one application or website to another)? Can these behaviors - regardless of their content - also predict psychological Why people turn to terrorism, and especially suicidal terrorism?What are the major reasons? It’s typically a combination of big is sues and little ones, or what som e call “push and pull” factors. The bigger issues include alienation, shared anger or outrage (e.g. at some foreign policy), frustration, disillusionment, a sense of victimization by the actions, or in the case of Syria, inactions, of others.The littler is sues, the “lures” include the perceived benefits of turning - e.g. adventure, excitement, camaraderie, a sense of belonging,being part of something far bigger etc. The key to understanding is not just to ask why people turn but how they turn, and what strategies recruiters use in that process. Effective recruiters will use whatever tools in their arsenal to pull someone in, whether it is convincing them of their duty to go fight in defense of others,to convincing them that involvement offers them a way out of the humiliation and victimization the recruiter will remind the young person they are otherwise destined to face at home. Radicalization,and how it relates to recruitment (and how we respond to it) is a constantly changing system. Some extreme traits are not as disadvantageous for fitness, as they appear to be for social adaptation or well-being, even when severely disordered subjects are examined.In fact, some traits increase in severity, they become more advantageous for attracting more mates and even producing more offspring.This would characterize these traits as risky shortcuts to fitness, owing less to failures than to the twists and turns made by genes in order to perpetuate themselves.Why someone joins today is different to why someone might have joined even the same group three years ago. The idealism that helps draw someone into terrorism 1characteristics?Assume we can monitor some people’s Internet use. We didn’t know what people were looking at on the internet (for example, depressed person - a dead giveaway), but merely how they were using the internet. None of the data categories gave specific information about what websites people were visiting, the content of their emails or chats, or the types of files being downloaded - they simply indicated the extent to which people used different broad categories of net-based resources, as well as differences in people’s tendency to use many resources at once.Task 1: Build a mathematical model to obtain a risk index, so we can evaluate the situation of each monitored person use it.Task 2: Experts use the expression big data to indicate huge amounts of information. We’ll get a lot of monitoring data, Please develop a series of statistical techniques to categorize them in an effective, fast and automatic manner.Task 3: If President Obama asked for your advice on fighting terrorism, what would you tell him? What should he do about ISIS?*Your ICM submission should consist of a 1 page Summary Sheet and your solution cannot exceed 20 pages for a maximum of 21 pages.C题翻译为什么人们转向恐怖主义，特别是自杀的恐怖主义？主要的原因是什么？它通常是一个大问题和小的组合，或者说什么叫做“推拉”因素。

2015年全国研究生数学建模竞赛C题（由华为公司命题）移动通信中的无线信道“指纹”特征建模一、背景介绍移动通信产业一直以惊人的速度迅猛发展，已成为带动全球经济发展的主要高科技产业之一，并对人类生活及社会发展产生了巨大的影响。

在移动通信中，发送端和接收端之间通过电磁波来传输信号，我们可以想象两者之间有一些看不见的电磁通路，并把这些电磁通路称为无线信道。

无线信道与周围的环境密切相关，不同环境下的无线信道具有一些差异化的特征。

如何发现并提取这些特征并将其应用于优化无线网络，是当前的一个研究热点。

类比人类指纹，我们将上述无线信道的差异化的特征称为无线信道“指纹”。

无线信道“指纹”特征建模，就是在先验模型和测试数据的基础上，提取不同场景或不同区域内无线信道的差异化的特征，进而分析归纳出“指纹”的“数学模型”，并给出清晰准确的“数学描述”。

在典型的无线信道中，电磁波的传输不是单一路径的，而是由许多因散射（包括反射和衍射）而形成的路径所构成的。

由于电磁波沿各条路径的传播距离不同，因此相同发射信号经由各条路径到达接收端的时间各不相同，即多径的时延之间有差异。

此外，各条路径对相同发射信号造成的影响各不相同，即多径的系数之间有差异。

如左下图所示：工程上，考虑到多径系数及多径时延的影响，在保证精度的前提下，可以用“离散线性系统”为无线信道建模。

需要注意的是，该模型中的信号及多径系数均为复数。

理想信道测量可以理解为获取该系统的单位序列响应，即获取单位脉冲“”经无线信道传输后被接收到的信号，如右上图所示。

上述理想信道测量的结果用公式表述如下:其中，“”为离散信号的样点标识，这里假设共有“”个样点；“”是当前时刻的路径总数；“”为当前时刻第条路径上的信道系数，通常是复数；“”为当前时刻第条路径的时延，且已折算成样点数，即延迟了“”个样点。

显然，复信号“”给出了当前时刻的完整信道。

需要强调的是，上述各个参数，包括“”、“”和“”都会随着时间而变化，即各个参数具有时变性。

A题The 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.世界医学协会日前宣布，其新的药物可以阻止埃博拉病毒和治愈患者的疾病，谁的病没有进入晚期。

因此，建立一个现实的、合理的，并且有用的模型是认为制造的疫苗或药物的不仅是这种疾病的传播、所述药物的所需要的数量、可能的可行交付系统、交付地点、制造的疫苗或药物的速度，但也可以是任何你的团队认为有必要为模型做贡献的其他关键因素，以便优化消灭埃博拉病毒或者至少抑制其目前的压力。

sin : sin s sin : sin 90
（7）
式中， 为太阳赤纬； 为按（3）式计算黄赤交角。上式可写为：
sin sin *sin s
（8 ）
太阳相对于观测点的位置
本研究采用观测点的地心天顶距 来表示太阳在某时刻相对于某一点的位
置，设观测点的经纬度 、 ，则可由下式计算某时的地心天顶距：
模型二的建立与求解
已知确定月亮位置的太阳参数表示如下：
h 279.69668 36000.76892T 0.00030T 2
（12） （13）
2327'8.261'' 46.845'' T 0.0059'' T 2 0.00183'' T 3
根据布朗在 1919 年给出计算月亮位置的天文参数 s ， p ， N ，其中 s 为月 亮的平黄经，其角速度为每小时 0.5490165 ， p 为月亮在近地点的平黄经，其 角速度为每小时 0.0046418 ， N 为月亮升交点的平黄经，其角速度为每小时 0.0000020 。其计算公式如下：
2015 高教社杯全国大学生数学建摘 要
“月上柳梢头，人约黄昏后”里面所提到的约会时间，就是月出与黄昏后同 时出现的时间段。本文通过建立数学模型，并以北京为例,计算了北京的各参数 值，与现实数据作比较来验证模型，再判断什么条件下会出现“月上柳梢头，人 约黄昏后”这一现象，从而给出黄昏后的定义以及发生这一情景的条件。然后根 据条件，利用 Excel 表格对哈尔滨、上海、广州、昆明、成都、和乌鲁木齐这六 个城市的经纬度、日落时间、月出时间、以及日落月出时间差等进行了计算和统 计，通过分析比较，从而判断出各个城市地区能否出现“月上柳梢头，人约黄昏 后”这一现象。 关键词：地心天顶距，日落，月出，月亮高度，黄昏后