第一篇：钢铁材料概述及其应用
钢铁材料概述及其应用
钢铁是铁与碳、硅、锰、磷、硫以及少量的其他元素所组成的合金。其中除铁外，碳的含量对钢铁的机械性能起着主要作用，故统称为铁碳合金。它是工程技术中最重要、用量最大的金属材料。
钢铁工业是最重要的基础工业，是其他工业发展的物质基础。钢铁工业的发展也有赖于煤炭工业、采掘工业、冶金工业、动力、运输等工业部门的发展。由于钢铁工业与其他工业的关系十分密切，因此许多国家都把发展钢铁工业放在十分重要的地位。
2022年，全球钢铁产量达13.45亿吨。其中我国铁、钢、材产量分别达到4.69 亿吨、4.89亿吨和5.65 亿吨。占全球钢产量份额由 2000年的 15.0%，提高到了 2022年的36.4%。钢铁按化学成分分类可分为碳素钢和合金钢。碳素钢是指钢中除铁、碳外，还含有少量锰、硅、硫、磷等元素的铁碳合金，按其含碳量的不同可分为：低碳钢（wc≤0.25%）、中碳钢（0.25%
按冶炼设备分可分为转炉钢、平炉钢、电炉钢。
按钢的品质分可分为普通钢（ws一般≤O.05%，wP≤0.045%）、优质钢（ws、wp≤0.04%）、高级优质钢（ws≤O.03%，wP≤0.035%）。按钢的用途分可分为结构钢（建筑及工程用结构钢、机械制造用结构钢）、工具钢（碳素工具钢、合金工具钢、高速工具钢等）和特殊钢（不锈耐酸钢、耐热不起皮钢、高电阻合金、耐磨钢、磁钢等）。
按制造加工形式分可分为铸钢、锻钢、热轧钢、冷轧钢和冷拔钢。下面简要概述具有代表性的钢铁材料的应用：
碳素结构钢是指wc<0.38%，ws，wp>0.035%的碳钢，可轧制成钢筋、钢板、钢管，用做螺钉、螺帽、铆钉等，也可做桥梁、建筑物等构件。
优质碳素结构钢是指wc<0.70%，ws，wp<=0.035%的碳钢，主要用来制造各种机器零件，如齿轮、轴类、套筒、弹簧等。
碳素工具钢的碳质量分数在0.65%～1.35%之间的碳钢，用来制造各种刃具、量具、模具，如（冲头、凿子、锤子、钻头、刨刀、丝锥、手锯条、锉刀、刮刀等）。低合金高强度结构钢，碳质量分数不超过0.20%，合金元素以锰为主，主要用于制造桥梁、船舶、车辆、锅炉、高压容器、输油输气管道、大型钢结构等。
合金渗碳钢碳质量分数一般为0.10%～0.25%，零件表层含碳量较高，可达0.85～1.05％，主要合金元素有Cr、Ni、Mn、B等，以提高淬透性。主要用于制造汽车、拖拉机中的变速齿轮，内燃机上的凸轮轴、活塞销等机器零件。
合金调制钢含碳量在0.25～0.50％之间，主加合金元素Cr、Mn、Ni、Si等，常用于制造汽车、机床上的主要零件，如机床的连杆、齿轮、传动轴等。弹簧钢，含碳量在0.40～0.70％之间，主加元素Si、Mn、Cr，用来制造弹簧等弹性部件。
滚动轴承钢含碳量在0.95～1.15％之间，铬为基本合金元素，主要用来制造滚动轴承的滚动体、内外套圈等。
第二篇：应用语言学概述
应用语言学概述
一、应用语言学的起源
19世纪初，语言理论方面的研究和应用方面的研究开始分化，语言教学从理论语言学中分化出来。19世纪末叶，博杜恩·德·库尔德内提出了应用语言学这个概念，但是没有得到广泛的注意。20世纪以后，语言学得到了进一步的发展，应用范围空前扩大，语言应用方面的研究和理论方面的研究明确地区分开来，应用语言学这个名词开始广泛运用。应用语言学涉及的领域很广泛，通常分为一般应用语言学和机器应用语言学。
二、课本内容总结
（一）应用语言学的基本概念
本单元谈到的第一个问题就是什么是应用语言学。应用语言学在广义上指关于语言学应用的所有的分支，其中包括政治、计划、来源、机器翻译、人工语言等多个方面，从此依旧体现出来语言学是一个综合性、多样性的学科。狭义上一方面为应用语言学在语音、语义等方面的语言学知识，另一方面指的是应用语言学在语言教学方面的应用。其次，语言学是一个综合性学科，涉及到语言的获取（语料库的收集）、语言的分析（话语分析）、语言的发展过程、心理语言学的实验，大脑的认知等都方面来源的知识。充分体现了语言学综合性、实验性、和实践性的特征。二语习得属于应用语言学的一个分支，两者有一定的重叠，在实验性方面有相同点。语言教学方法是应用语言学很重要的部分，其中包括应用语言学中一切有关教学的知识。
（二）对比语言学和二语习得
首先，对比语言学和二语习得对于应用语言学的研究都有一定的促进作用。其次，对比语言学从属于应用语言学，小于等于应用语言学，王力学者曾说过，外语教学最有力的方法是中外语言的比较教学。实质对比语言学的适用于所有语言的习得。对比语言学其中会对比语言本身（音位、词素、语法）和文化。再者是二语习得的两个特点（正、负迁移）和语言转移的关系，一部分的教育现象就是语言转移的特征。
（三）交际能力
这是一个现实到认知再到语言的过程，而交际能力是教育最为重要的目的，教育的目的就是充分发挥语言的最大作用达到交流的有效结果。这一部分是社会语言学的知识，同样也是应用语言学众多分支之一。在交际能力和教学方法结合的时候，认知语言学显得尤为重要。认知语言学涉及人工智能、语言学、心理学、系统论等多种学科，它针对生成语言学天赋观，提出：语言的创建、学习及运用，基本上都必须能够透过人类的认知而加以解释，因为认知能力是人类知识的根本。认知语言学不是一种单一的语言理论,而是代表一种研究范式,是多种认知语
言理论的统称,其特点是把人们的日常经验看成是语言使用的基础,着重阐释语言和一般认知能力之间密不可分的联系。这些语言理论虽不相同,但对语言所持的基本假设都大同小异,都不同程度地认可上一节提到的基本观点,只是在讨论和关注的具体语言现象上有所差别。
（四）文化与跨文化交际可以概括为语言是文化的输出工具，文化是语言的凝练总结，教授语言就是教授该语言存在的文化。笼统地说，文化是一种社会现象，是人们长期创造形成的产物，同时又是一种历史现象，是社会历史的积淀物。确切地说，文化是凝结在物质之中又游离于物质之外，能够被传承的国家或民族的历史、地理、风土人情、传统习俗、生活方式、文学艺术、行为规范、思维方式、价值观念等，是人类之间进行交流的普遍认可的一种能够传承的意识形态。从此可以看出学习文化对研究应用语言学的重要性。对于二语习得者，学习文化有效地方法就有对比学习和跨文化交际（出国留学等），文化存在于语言应用的每一个环节和细节中，因而教学中不能只重视词汇和语法，文化也是必不可少的一部分。对于教学方面同社会语言学有一定的联系，语言可以表达思想，传播文化，文化和思想是语言的存在意义。
（五）心理语言学和多语言习得的过程
本单元首先对比了母语和二语习得者的差别，主要表现在认知过程中获取信息的技巧，从而总结出了二语习得者正确高效的学习方法。其次，心理语言学家想要证明理解和记忆语言功能的器官的存在，这一论题来自于心理学，可以在语言习得中体现出来。在语言习得过程中兴趣是学习的基础，而每个人的学习方法都不相同，是因为每个人的词汇储备和说话风格等个人因素的影响。重要的是在语言习得过程中学习者心理活动很大程度上影响了学习的结果，也就是我们书上说的心理语言学对二语习得者的作用。
（六）语料库和应用语言学
语料库是语言学研究过程中迄今为止最有效的研究方法，语料库是所以研究对象的集合，语料库根据其功能可以分为特殊语料库、普通语料库、对比语料库、类似语料库、学习者语料库、教学者语料库、历史语料库和成长语料库。语料库的应用需要有计算机辅佐完成，还要搭配一系列的语言分析工具。分析方法大概有从普通到特殊的总结、测试某一项的用法、对比语料的不同还有计算某一词素出现的概率。当下语料库主要应用于词典的编纂和封闭语料的定向研究。
（七）语篇分析和应用语言学
本单元的话语分析主要是口语方面的分析，第一项工作要确定研究对象，研究的方面主要有说话人的发言顺序、说话时的错误分析还有说话时的词汇选择。错误提供反馈，它可以告诉教师教材和教学方法产生了什么效果，并且也向他们提出所依据的教学大纲中哪部分在教与学的过程中还有什么不足，需要重视。分析时还要重视在特殊场合研究对象的话语分析。对于多语者的话语分析通常会遇到文化和语法的评价。综上，话语分析帮助确定教学目标和方法，改进教学大纲起着决定性作用。
（八）话语分析和语言教学
本单元特指书面语的话语分析，其目的在于提高二语习得者的写作能力。通过大量的母语语料的研究总结出来贴近的写作框架，供二语习得者利用更好的表
达自己的想法，使二语习得者的写作更加接近母语者。系统的分析方法会分析语法、结构和体裁。把二语习得者和母语者的作文进行比较，从而找到有效地写作方法加以效仿。此外，还要明白语言学存在与我们生活的每一个地方，社会语言学重视各种方言的研究。话语分析属于功能语言学的一部分。
（九）教学大纲设计和语言项目
一个制定得好的教学大纲就是教学程序的全面计划，常见的教学大纲有结构性语言教学大纲、交际教学大纲、理论教学大纲、情景教学大纲和任务型教学大纲。和课程相关的就是一般情况小都是根据语言学合理性的次序排列来设计大纲的，其中有个教学内容的部分就是我们谈到的大纲设计。我们重视的是以技能为基础的教学大纲，这才体现到了学习语言的目的。教学大纲的设计是一种艺术，牵涉到语言学、教育学、社会语言学和心理学方面的问题，要懂得因材施教才是王道。
（十）语言学习者和教学者的提高
这个单元的主要任务是在最大程度发挥老师自己特长的情况下，找到帮助老师更好的完成教学任务的方法。这个过程中，会出现四个方面的问题：课本、学生、管理过程和方法和教学器材准备。其中，学生要最大程度的学会听课，配合老师；管理层应及时和老师沟通，给予一定的鼓励和支持。才外，我们应该学会评价教学，有三点必须考虑：连贯性、扩展性和有效性。充分发挥老师的职能，调动学生的积极性，互动中学习，更加专业化的教学。
（十一）学习者的个人因素和个性
语言学家最常讨论的几个问题就是什么年龄适合学习二语，天赋到底会不会影响二语的学习，在学习中认知特征是怎么作用的，还有个人因素（学习态度、个人喜好）对学习的影响。在学习和教学中这些问题都是不可避免的，这时就需要老师可以平等对待每一位学生，尽最大努力做到因材施教，这关系到老师的教学态度和个人修养问题。
（十二）测评和评估
语言学应用于语言教学，不仅是一个描写性的活动，还是一个指示性的活动。因此我们都追求提高学习效率，那么应该要意识到的是教材并不是提高语言学习效率的唯一因素。现在我们有不同性质的测评方法，多样性和综合性的评估原则。衡量和评价是两个性质不同、但又是逻辑上相互关联的过程。衡量学生的知识，不仅是评价学生本人也是评价教师和教材的一种手段。测评和评估也应该与时俱进，创新与发展。
三、应用语言学和语言教学
本书的每个单元最后一部分都是应用语言学在教学方面的表象，足以表现这是一本关于语言教学的狭义应用语言学的简单概述。其中包括了语言学家、心理语言学家、社会语言学家和认知语言学家等很多人的观点，说明应用语言学是一个人庞杂的学科。
浅谈批评性话语分析
批评性话语分析(critical discourse analysis)，简称CDA，也叫做批评语言学(critical linguist ics)，旨在通过分析语言特征及其生成的社会文化背景挖掘隐含于语言中的意识形态, 进而揭露语言、权势和意识形态之间的复杂关系。批评性话语分析诞生于20 世纪70 年代，英国语言学家Fowler 等在《语言和控制》(Language and Control)一书中首次提出批评语言学这一概念, 揭开了批评性话语分析研究的序幕。
批评性话语分析被认为是批评语言学最有影响的一个分析，它通过分析大众语篇揭示意识形态对语篇的影响和语篇对意识形态的反作用。不同学者对批评话语分析的诠释不尽相同。批评性话语分析家认为话语是影响人们思想和实践的强有力方式, 因而有必要通过详细分析揭示其中的权势关系。
在语言学上，批评性话语分析吸收了美国人类学家Sapir & Whorf关于语言和思维关系的假说(语言相对论和语言决定论)以及Halliday 系统功能语言学(Systemic Functional Linguistics)的理论, 主张人们在使用语言时所选择的语言形式是由其实现的社会功能所决定的(选择即意义)，而CDA正是主张语言是一种社会实践, 试图使人们意识到以前所没意识到的语言和社会结构之间相互影响的关系。
Fairclough提出了批评性话语分析的三大论点：(1)语言是一种社会实践(social practice)，它是社会秩序的一种永恒的介入力量，从各个角度反映现实，通过再现意识形态来操作、影响社会过程。(2)在社会文化环境中，语言与价值观念、宗教信仰和权力关系之间是一种互为影响的关系。(3)语言的使用可以促使话语的改变和社会的变革。Fairclough 承认批评性话语分析并非“毫无激情而纯客观的”社会科学,批评性话语分析家都是带着激情和强烈的责任感而投入工作的。批评性话语分析的独特之处就是它帮助被统治和被压迫群体反对统治者。它公开表明自己的动机是为被压迫群体谋求解放。这并不意味着批评性话语分析缺少坚实的理论基础,也不意味着批评性话语分析的学术标准低或方法不严谨。Fairclough 和Wodak阐述了批评性话语分析在理论和方法上应遵循的八条原则：
1.批评性话语分析关注的是社会问题
2.话语反映权力关系
3.话语是社会和文化的构成要素
4.话语是意识形态的工具
5.话语具有历史关联性
6.语篇与社会的关系是间接的7.话语分析是解释性的8.批评性话语分析是社会行动
批评性话语分析的主要方法有：系统功能语法分析、语篇体裁交织性分析、话语历史背景分析
按照 《现代语言学词典》 的解释,“批评话语分析是一种分析视角, 研究的是话语事件和社会政治, 文化因素之间的关系, 特别是话语在社会中如何在意识形态上受权势关系的影响和自身如何影响权势关系。”看来，批评话语分析的生命在于“ 批评”，批评话语分析的产生和发展都会受到政体的制约。任何社会科
学都或多或少带着一定的政治偏见。批评性话语分析也不例外,它公开表明自己的动机是帮助被统治和被压迫群体反对统治者。但这并不意味着批评性话语分析缺少坚实的理论基础,也并不意味着批评性话语分析的学术标准低或研究方法不严谨。从本文介绍的理论渊源、原则和方法来看,批评性话语分析有坚实的理论基础和科学的分析方法。当今西方世界在社会文化方面所取得的进步,有不少是批评性话语分析家努力的结果。
学习反思
批评性话语分析是西欧语言学界从20世纪70年代末至80年代初发展起来的一种语言学思潮。批评话语分析致力于解释语言和社会结构之间的相互作用并积极参加与当代这种社会具体问题的研究和实践，所涉及的主题有政治话语、意识形态、种族主义、全球化、经济话语、广告和推销文化、媒体话语、性别、机构话语、语文教育等。由于意识形态具有合法化、习惯化以及相对隐藏的特性，我们面对所有信息的过程中对语言有高度的敏感性，并对其进行批评性分析，掀开某些语言过程和社会语言过程的面具，揭示那些用于超控、歧视和蛊惑的语言，树立批评性话语分析观，从而正确地把握其中蕴藏的意识形态和价值观。
参考文献
1.毛浩然，《话语分析理论的温故与知新》，河北北方学院学报
2.纪玉华，《批评性话语分析：理论与方法》，厦门大学学报
3.懂又能，王晶晶，《英语新闻的批判性话语分析》，湖北大学学报
第三篇：遥感技术应用概述
遥感技术应用概述
很多人以为遥感离自己的生活很遥远，其实这些技术早就已经深入大家的生活。从上个世纪六十年代提出“遥感”这个词，到1972年美国陆地卫星计划发射了第一颗对地观测卫星（LandSat）,经过几十年的发展，遥感技术已经广泛地应用在军事、国防、农业、林业、国土、海洋、测绘、气象、生态环境、水利、航天、地质、矿产、考古、旅游等领域，影响了人类生活的方方面面,它为人类提供了从多维和宏观角度去认识世界的新方法与新手段，遥感技术能够全面、立体、快速有效地探明地上和地下资源的分布情况，其效率之高是以前各种技术无法企及的。因此，遥感技术已成为一门实用的，先进的空间探测技术。下面就三个方面介绍一下遥感技术：
一、“3S”技术的涵义：
包括RS、GPS、GIS。
RS即遥感技术是指从地面上空的飞机、飞船、卫星等飞行器上，利用各种波段的遥感器，通过摄影、扫描、信息感应，识别地面物质的性质和运动状态的技术，具有遥远感知事物的意思。
GPS即全球定位系统，是一种同时接收来自多颗卫星的电波导航信号，测量地球表面某点准确地理位置的技术系统；
GIS即地理信息系统技术，是利用现代计算机图形技术和数据库技术，用以输入、存储、编辑、分析、显示空间信息及其属性信息的地理资料系统。分为两大类： 第一类是地图数据或图形数据；第二类是文字数据或非图形数据。
二、遥感技术的主要特点：
可获取大范围数据资料。遥感用航摄飞机飞行高度为10km左右，陆地卫星的卫星轨道高度达910km左右，从而，可及时获取大范围的信息。例如，一张陆地卫星图像，其覆盖面积可达3万多平方公里。这种展示宏观景象的图像，对地球资源和环境分析极为重要。
获取信息的速度快，周期短。由于卫星围绕地球运转，从而能及时获取所经地区的各种自然现象的最新资料，以便更新原有资料，或根据新旧资料变化进行动态监测，这是人工实地测量和航空摄影测量无法比拟的。例如，法国SPOTS5卫星重复覆盖地球周期为1-5天，NOAA（美国国家海洋和大气局）气象卫星一天能收到两次图像。美国气象卫星（meteorological 和 satellite 缩合）每30分钟获得同一地区的图像。
获取信息受条件限制少。在地球上有很多地方，自然条件极为恶劣，人类难以到达，如沙漠、沼泽、高山峻岭等。采用不受地面条件限制的遥感技术，可方便及时地获取各种宝贵资料。
获取信息的手段多，信息量大。根据不同的任务，遥感技术可选用不同波段和遥感仪器来获取信息。例如可采用可见光探测物体，也可采用紫外线，红外线和微波探测物体。利用不同波段对物体不同的穿透性，还可获取地物内部信息。例如，地面深层、水的下层，冰层下的水体，沙漠下面的地物特性等，微波波段还可以全天候的工作。
三、遥感技术的应用
1、地质遥感遥感技术应用于大面积的地质灾难调查，可达到及时、具体、准确且经济的目的。在2022年“5.12”汶川大地震的后续救援工作中，遥感技术就发挥了突出作用，第一时间提供了地质地貌变化情况，为政府作出正确决策提供了依据。在舟曲泥石流灾害中，中国科学院对地观测与数字地球科学中心科研人员就使用遥感技术，重点提取了6条沟谷与泥石流发生有关的信息，得到集水面积、流域平均坡度、流域落差和植被覆盖度等参数。经过分析，科研人员判断出，当地哪些地方仍存在泥石流隐患，哪些地段发生大型泥石流的可能性较小，让前方人员可以更有针对性地安排救灾工作。地震预报是举世瞩目的科学难题，利用红外遥感资料进行地震预报和监测已取得了巨大的成功, 1991年3月，观察山西省大同5.8 级地震前卫星热红外遥感图象后发现，震前4～6 天在局部地区出现地表温度场发生增温现象或称暂时异常“热岛”现象, 异常带长80km, 宽30km，距离震中25km，地表亮度温度变化数值由22℃增加到28℃，部分欧美发达国家已进入了实际研究和应用阶段。
2、环境遥感
遥感技术应用于环境监测上既可宏观观测空气、土壤、植被和水质状况，为环境保护提供决策依据，也可实时快速跟踪和监测突发环境污染事件的发生、发展，及时制定处理措施，减少污染造成的损失。其从空中对地表环境进行大面积同步连续监测，突破了以往从地面研究环境的局限性。例如：每年夏收后的秸秆燃烧是个让当地政府头疼的问题。过去监察人员坐车巡查，能去的地方少，大部分火点都被漏掉。现在气象和环保联手，遥感中心通过卫星监测火点，分辨率高达250米的卫星定位可以精确到乡镇，让秸秆燃烧无处遁身，保证环保人员能有效执法。在2022年6月6日全国秸秆焚烧公布的遥感监测结果中，山西省有3个火点，其中就有介休市1个火点，具体位置在禁烧区省道旁经度111.98度，纬度37.082度上。
3、林业遥感
在林业方面，利用遥感技术可以清查森林资源，监测森林火灾和病虫害。火灾是林业的大敌，利用航空红外遥感技术，不仅能发现已燃烧起来的烈火，而且可以探测到面积小于0.1-0.3㎡小火情，还能及时预报由于自燃尚未起火的隐伏火情。利用卫星遥感，一次就可探测到上千平方千米范围内发生的林火现象。卫星遥感防火监测服务在吉林省森林和草原防火工作中发挥了重要作用，对于人烟稀少的原始林区，能及时监测到瞭望岗哨难以发现的火点，为林火的扑救赢得时间，2022年春季防火期间卫星遥感防火监测服务在吉林省森林和草原防火工作中发挥了重要作用。共向吉林省森林防火指挥办公室和草原防火办公室通报热点87处，出色地完成了吉林省春季防火任务，为保卫吉林省实现连续30年无重大森林火灾的目标做出了贡献。
4、测绘遥感
人造卫星每隔18天就可送回一套全球的图像资料。利用遥感技术，可以高速度、高质量地测绘地图。
5、军事遥感
在伊拉克战争中，遥感技术发挥了重要的作用，如打击目标的确定，水源的发现，地下坑道的发现，隐藏所的目标锁定等。为战争的战略指挥和后勤工作做了充分的准备，最大限度的发挥攻击效益，极大的增强了军队战斗力。自动化侦察系统，搜集预处理情报系统，自动化通信系统，气象侦察等，充分保障了空中、地面作战的进行。
遥感技术获得的信息探测范围大，资料新颖，而且为动态变化，还可迅速成图，搜集方便，不受雨雾、地形等条件的限制。科索沃战争就是一场现代化的信息战，科索沃上空20多颗卫星进行了追踪定位侦察，监视部队动态变化并及时传递信息，制导轰炸。阿富汗战争更有着太多的始料未及，B-52的远程轰炸，直接从美本土起飞，飞行上万里，且目标准确，由于传感的精确指导，美泊于印度洋上的航空母舰直接进行导弹发射，阿富汗多山的优势，在遥感监听下亦丧失殆尽，崇山峻岭中山洞的防御亦不能逃脱精确制导的打击，微波的功能让塔利班地下工事无所遁形。
6、农业遥感
农业遥感是指利用遥感技术进行农业资源调查，土地利用现状分析，农业病虫害监测，农作物估产等农业应用的综合技术，是当前遥感应用的最大用户之一。在2022年的中央一号文件中写到“鼓励有条件的地方在农业生产中积极采用全球卫星定位系统、地理信息系统、遥感和管理信息系统等技术。”可见遥感在农业中的重要地位。
①．农作物估产与监测2022年以来，利用遥感估产运行系统得到的冬小麦、玉米的长势、墒情、面积和产量监测结果一直纳入农业部“农情信息发布日历”,成为农业部粮食会商的3大信息渠道之一,通过农业部官方网站对外发布。像遥感站所进行的冬小麦监测、玉米监测就是遥感估产运行系统中的地面调查系统。
②．“3S”集成技术在精细农业中的应用遥感和GIS结合提供多种数据源，这为建立农田基础数据库奠定了基础。农田基础数据库是农田科学管理的基础。搭载在拖拉机和联合收割机上的地理信息系统可以记录下各种农田操作过程中获得的数据，如作物品种、播种深度、喷洒农药类型以及收获产量，同时记录下田间作业时的位置与范围，灌溉量、化肥使用量、农药喷洒量、喷施部位、使用时间、当时天气状况等，这些都可以记录在数据库内，日积月累，形成农田生产辅助决策系统的重要科学依据。GIS能够根据地块中的土壤结构、有机质含量和土地平整度，结合GPS接收机提供的位置数据，指挥播种机进行定量播种，播种的疏密程度与土地肥力和土壤质地等作物生长环境相适应。在GIS和GPS指挥下，农药喷洒机可以在病虫害发生地去自动喷洒农药。
③．在病虫害防治中的应用在小麦生产中，小麦条锈病是损失大、危及范围最广的一种病害。长期以来，我国对小麦条锈病的监测工作仅限于田间取样调查。但是，针对大面积病害的监测，采用人工调查不仅耗费大量人力物力，而且监测效率很低，等病情上报到有关部门时，往往病害已大范围暴发。在国家自然科学基金的支持下，中国农业大学农学与生物技术学院副院长马占鸿教授带领的研究团队已能够利用卫星遥感技术对我国主要小麦品种实施条锈病病情监测。和人工进行农作物病虫害监测相比，采用卫星遥感监测效率更高，精度更高。
④．农情监测 农情参数的获取可以用于指导农田的生产管理，实行变量投入，达到优化生产、提高生产率、减少污染，是现代化农业发展的趋势。遥感技术具有覆盖范围大、探测周期短、现时性强、费用成本低的特点，为农情参数快速、准确、动态地获取提供了重要的技术手段。
⑤．农业资源调查和动态监测遥感技术使农业动态监测工作可以从几公里甚至几万公里的高度俯视地面资源及其变化，从而开拓了人们的思路和视野，为农业资
源调查、监测提供了更先进、更科学、更有效的方法。山西省遥感中心利用遥感技术进行农业资源调查和动态监测经费是常规方法的1/5-1/10，人力是1/10-1/20，时间是1/5-1/10，经济效益可观，还取得了较好的生态效益。
总之，卫星遥感技术的迅速发展，把人类带入了立体化、多层次、多角度、全方位和全天候地对地观测的新时代。就在我们为在网络上通过Google Earth的卫星影像可以看到自己家的房顶感到震撼时，现在我告诉大家：在网络上不仅能搜索到自己家，还能看见阳台上种的几盆花，甚至可以判断哪几盆要浇水；当我们站在某个海滩边，掏出手机，就可以接收到卫星遥感发回的数据：附近哪里阳光充足、哪里的沙滩沙多，哪里的海水污染较少，哪里游泳水温比较合适，这会不会吓到你？中国正在开发比“谷歌地图”更精细的卫星系统——高分辨率对地观测系统。到2022年，借助该系统，上述的场景就真能实现了，到时我们就可以把整个地球装进自己的口袋。
第四篇：应用文体概述
应用文体概述
设计者：授课时间：
一、教学目标：
1、理解什么是应用文，掌握应用文的特点。
2、了解应用文的分类和应用文写作的重要意义。
二、教学重点：
1、使学生了解应用文的分类和特点，2、认识到应用文的实用性及重要性。
三、教学方法：
讲授法，对话法，比较法，自主，合作
四、课时安排：2课时
五、教学过程：
首先教师提问问题，什么是应用文？学生根据自己的理解自由回答。根据学生所答内容，进行引导并进行总结。
1、应用文的含义
应用文是指 单位或个人为处理个人事务、解决具体问题而写作的具有惯用格式的一种文体。
2、应用文写作的含义
又称 公文写作，就是根据现实的需要，运用应用文的文体知识，创作出具有较强实用意义的作品的过程。
举例子：（当今社会，信息高速发展，生活节奏日益加快，无论是经商、从政、学习还是日常生活中简单的人际交往，信息的处理和传播都占据着举足轻重的地位，人们越来越离不开应用文的写作了。例如：双方发生借贷关系，借款方要写出借据，证明借贷关系的存在，朋友之间的书信，message，电子邮件，重要物品遗失，寻物启事，启事也是一种应用文体，总之应用文体多种多样，也是几乎囊括生活的各个方面，应用文写作无处不在。）
教师使学生列举出所知道的所有应用文文体。列入板书，并找同学进行分类。从而导出应用文的种类和特点。
3、应用文的种类
行政公文类是以党和国家机关 社会团体 企事业单位的名义发出或记录某种信息时使用的一类应用文。公告 通告 通知 通报 报告 议案 会议纪要等 事务类文书就是指机关 团体 企事业单位或者个人在处理日常事务时所普遍使用的一种应用文。启事与声明 计划 总结 简报开幕词 述职报告等
经济类文书主要指人们在经济活动中所使用的应用文合同 协议书 广告 商品说明书等
法律类文书 是指诉讼司法文书 在法律活动中使用的应用文起诉状 申诉状仲裁申请书等
科技类文书是指在学习科学研究 技术创新活动中使用的文书实习报告 毕业论文科技论文等
传播类文书人们在信息传播过程中使用的一种应用文新闻 通讯 广播稿 演讲稿 解说词等
礼仪类文书人们在社交活动中使用的一类应用文。请柬 聘书 祝词 欢迎词等
根据以上所讲内容，小组讨论应用文特点，并找代表回答：
4、应用文的特点
1、具有实用性合同 计划海报
2、有特定的对象经济合同书文学作品投标书
3、有较为固定的惯用格式 书信开头 结尾等
4、有较强的实效性请假条通知
5、应用文的语言要简明、准确。2月27号前来上课
5、应用文的作用
1、宣传教育指导工作
2、传递信息 协调沟通
3、作为依据和凭证。
4、提供和保存资料。
6、写作应用文的注意事项
1、要熟悉政策法规，具有较高的政策水平
2、要有较宽的知识面 交丰富的只是储备
3、要具备较强的文字表达能力
4、掌握规范的格式。
六、随堂提问并总结
1、应用文含义？
2、应用文种类至少说出4种？
3、应用文特点有哪些？
七、作业：
1、应用文含义
2、应用文种类
3、应用文特点
八、教学总结
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第五篇：嵌入式Linux应用：概述
Embedded Linux applications: An overview Linux now spans the spectrum of computing applications, including IBM's tiny Linux wrist watch, hand-held devices(PDAs and cell phones), Internet appliances, thin clients, firewalls, industrial robotics, telephony infrastructure equipment, and even cluster-based supercomputers.Let's take a look at what Linux has to offer as an embedded system, and why it's the most attractive option currently available.One.Emergence of embedded systems The computers used to control equipment, otherwise known as embedded systems, have been around for about as long as computers themselves.They were first used back in the late 1960s in communications to control electrome chanical telephone switches.As the computer industry has moved toward ever smaller systems over the past decade or so, embedded systems have moved along with it, providing more capabilities for these tiny machines.Increasingly, these embedded systems need to be connected to some sort of network, and thus require a networking stack, which increases the complexity level and requires more memory and interfaces, as well as, you guessed it, the services of an operating system.Off-the-shelf operating systems for embedded systems began to appear in the late 1970s, and today several dozen viable options are available.Out of these, a few major players have emerged, such as VxWorks, pSOS, Neculeus, and Windows CE.Two.Advantages/disadvantages of using Linux for your embedded system Although most Linux systems run on PC platforms, Linux can also be a reliable workhorse for embedded systems.The popular “back-to-basics” approach of Linux, which makes it easier and more flexible to install and administer than UNIX, is an added advantage for UNIX gurus who already appreciate the operating system because it has many of the same commands and programming interfaces as traditional UNIX.The typical shrink-wrapped Linux system has been packaged to run on a PC, with a
hard disk and tons of memory, much of which is not needed on an embedded system.A fully featured Linux kernel requires about 1 MB of memory.However, the Linux micro-kernel actually consumes very little of this memory, only 100 K on a Pentium CPU, including virtual memory and all core operating system functions.With the networking stack and basic utilities, a complete Linux system runs quite nicely in 500 K of memory on an Intel 386 microprocessor, with an 8-bit bus(SX).Because the memory required is often dictated by the applications needed, such as a Web server or SNMP agent, a Linux system can actually be adapted to work with as little as 256 KB ROM and 512 KB RAM.So it's a lightweight operating system to bring to the embedded market.Another benefit of using an open source operating system like Embedded Linux over a traditional real-time operating system(RTOS), is that the Linux development community tends to support new IP and other protocols faster than RTOS vendors do.For example, more device drivers, such as network interface card(NIC)drivers and parallel and serial port drivers, are available for Linux than for commercial operating systems.The core Linux operating system itself has a fairly simple micro-kernel architecture.Networking and file systems are layered on top of the micro-kernel in modular fashion.Drivers and other features can be either compiled in or added to the kernel at run-time as loadable modules.This provides a highly modular building-block approach to constructing a custom embeddable system, which typically uses a combination of custom drivers and application programs to provide the added functionality.An embedded system also often requires generic capabilities, which, in order to avoid re-inventing the wheel, are built with off-the-shelf programs and drivers, many of which are available for common peripherals and applications.Linux can run on most microprocessors with a wide range of peripherals and has a ready inventory of off-the-shelf applications.Linux is also well-suited for embedded Internet devices, because of its support of multiprocessor systems, which lends it scalability.This capability gives a designer the option of running a real-time application on a dual processor system, increasing total processing power.So you can run a Linux system on one processor while running a GUI, for example, simultaneously on another processor.The one disadvantage to running Linux on an embedded system is that the Linux architecture provides real-time performance through the addition of real-time software modules that run in the kernel space, the portion of the operating system that implements the scheduling policy, hardware-interrupts exceptions and program execution.Since these
real-time software modules run in the kernel space, a code error can impact the entire system's reliability by crashing the operating system, which can be a very serious vulnerability for real-time applications.An off-the-shelf RTOS, on the other hand, is designed from the ground up for real-time performance, and provides reliability through allocating certain processes a higher priority than others when launched by a user as opposed to by system-level processes.Processes are identified by the operating system as programs that execute in memory or on the hard drive.They are assigned a process ID or a numerical identifier so that the operating system may keep track of the programs currently executing and of their associated priority levels.Such an approach ensures a higher reliability(predictability)with the RTOS time than Linux is capable of providing.But all-in-all, it's still a more economical choice.Three.Different types of Embedded Linux systems There are already many examples of Embedded Linux systems;it's safe to say that some form of Linux can run on just about any computer that executes code.The ELKS(Embeddable Linux Kernel Subset)project, for example, plans to put Linux onto a Palm Pilot.Here are a couple of the more well-known small footprint Embedded Linux versions: ETLinux--a complete Linux distribution designed to run on small industrial computers, especially PC/104 modules.LEM--a small(<8 MB)multi-user, networked Linux version that runs on 386s.LOAF--“Linux On A Floppy” distribution that runs on 386s.uClinux--Linux for systems without MMUs.Currently supports Motorola 68K, MCF5206, and MCF5207 ColdFire microprocessors.uLinux--tiny Linux distribution that runs on 386s.ThinLinux--a minimized Linux distribution for dedicated camera servers, X-10 controllers, MP3 players, and other such embedded applications.Software and hardware requirements Several user-interface tools and programs enhance the versatility of the Linux basic kernel.It's helpful to look at Linux as a continuum in this context, ranging from a stripped-down micro-kernel with memory management, task switching and timer services to a full-blown server supporting a complete range of file system and network services.A minimal Embedded Linux system needs just three essential elements:
A boot utility
The Linux micro-kernel, composed of memory management, process An initialization process Drivers for hardware
One or more application processes to provide the needed functionality A file system(perhaps in ROM or RAM)TCP/IP network stack
A disk for storing semi-transient data and swap capability A 32-bit internal CPU(required by all complete Linux systems)management and timing services
To doing anything useful while remaining minimal, you also need to add:
As additional requirements become necessary, you might also want:
Four.Hardware platform options Choosing the best hardware can be complex because of internal company politics, prejudices, legacies of other projects, a lack of complete or accurate information, and cost, which should take into account the total product costs and not just the CPU itself.Sometimes a fast, inexpensive CPU can become expensive once bus logic and the delays necessary to make it work with other peripherals are considered.To calculate the necessary speed of a CPU for any given project, start with a realistic view of how fast the CPU needs to run to accomplish a given task and triple it.Also, determine how fast the bus needs to run.If there are secondary buses, such as a PCI bus, consider them also.A slow bus(that is, one that is saturated with DMA traffic)can significantly slow down a fast CPU.Here are some of the best hardware solutions for Embedded Linux applications.Bright Star Engineering: Bright Star Engineering's ipEngine-1 is a credit-card sized single-board computer with Embedded Linux support.It utilizes a PowerPC-based CPU and provides an array of on-board peripherals, including Ethernet, LCD/Video Controller, USB, Serial I/O, and a 16K gate user-configurable FPGA.BSE's Embedded Linux configuration allows Linux to be booted from the ipEngine's on-board 4MB flash memory.Calibri: CalibriTM-133 is a ready-to-use, compact, multipurpose network appliance
that uses Embedded Linux as its operating system.It offers a highly efficient and low-cost solution to firewall, VPN, and routing demands.EmbeddedPlanet: EmbeddedPlanet has created a PostPC-era computer that comes loaded with MontaVista's HardHat Linux.Powered by a PowerPC-based computing engine and matching I/O card, Linux Planet comes in a colorful translucent case with a touchscreen and access to digital and analog I/O.Eurotech: Eurotech provides embedded PC SBC and sponsors ET-Linux, a complete Linux system designed to run on small industrial computers and based on glibc 2.1.2.Microprocess Ingenierie: Microprocess develops, produces, and sells standard and customized products for the industrial and embedded market.Microprocess has a global activity in real-time software and great expertise in systems integration.Its products, like the 740 PowerPC compactPCI board, can be ordered with a standard distribution of Linux or an Embedded Linux version.Moreton Bay: Moreton Bay is releasing their NETtel 2520 and NETtel 2500 range of Linux-based Internet routers.These small, easy-to-connect intelligent router solutions are engineered to offer a simple, secure, and affordable extranet-friendly Virtual Private Network(VPN)for flat networks.The NETtel router family runs an Embedded Linux kernel.A development kit is available;it enables customized code to be stored in flash memory and executed inside the NETtel.The code may contain special encryption or authentication protocols, or some local monitoring script where NETtel is used as a remote control device.Matrix Orbital: This an optional, but not recommended, addition.Matrix Orbital manufactures a line of serial LCDs and VFDs, which many Linux users are including in their embedded systems.The product line ranges from 8x2 to 40x4 character LCDs, 20x2 and 20x4 VFDs, plus a 240x64 graphic LC(128x128 on the way).Communication with the displays is accomplished via either RS232 or I2C, both of which are standard on all of their modules.A comprehensive command set is included in the modules' BIOS.Five.Real-time Embedded Linux applications One of the most important issues with embedded systems is the need for a real-time operating system.The definition of real-time here varies quite a bit.To some people, real-time means responding to an event in the one-microsecond range, to others it is 50 milliseconds.The hardness of real-time also varies quite a bit.Some systems need hard
real-time response, with short deterministic response latencies to events.However, on many systems, when analyzed closely, we see a response time requirement that is actually near real-time.Often the real-time requirement is a tradeoff of time and buffer space.With memory getting cheaper, and CPUs getting faster, near real-time is now more typical than hard real-time and many commercial operating systems that claim to be real-time are far from being hard real-time.Usually, when you get into the detailed design of these systems, there are warnings that the drivers' interrupts and applications must be very carefully designed in order to meet real-time requirements.RT-Linux(Linux with real-time extensions)contains time critical functions to provide precise control over interrupt handling, through the use of an interrupt manager, and does a good job of making sure that critical interrupts get executed when needed.The hardness of this approach depends mostly on the CPU interrupt structure and context-switch hardware support.This approach is sufficient for a large range of real-time requirements.Even without the real-time extensions, Linux does pretty well at keeping up with multiple streams of events.For example, a Linux PC system on a low end Pentium is able to keep multiple 10BaseT interfaces executing effectively, while simultaneously running character-level serial ports at a full 56KBPS without losing any data.Some real-time hardware and software Linux APIs to consider are RTLinux, RTAI, EL, and Linux-SRT.RTLinux is a hard real-time Linux API originally developed at the New Mexico Institute of Technology.RTAI(DIAPM)is a spin-off of the RTLinux real-time API that was developed by programmers at the Department of Aerospace Engineering, Polytechnic Politecnico di Milano(DIAPM).EL/IX is a proposed POSIX-based hard real-time Linux API being promoted by Red Hat.And Linux-SRT is a soft real-time alternative to real-time APIs, which provides performance-enhancing capabilities to any Linux program without requiring that the program be modified or recompiled.See the Resources section later in this article for information on the above and for some Web sites offering different flavors of software extensions, development tools, support, and training courses for the standard Linux operating system.Short deterministic response latencies Some real-time embedded systems need to respond quickly to external events in order to accomplish a specific task.A custom microcontroller embedded inside a missile, for example, needs to respond quickly to external events such as moving targets, weather, humans, etc., before instructing the missile to target a specific object in its surrounding
environment.Short deterministic response latencies mean that the embedded system can determine the time it will take to respond to an external event.Six.Configuration procedures Now let's take a look at how to make LEM, a small, embeddable Linux distribution, which provides both network and X server.You can download this distribution, although it is not essential.You will need a full Linux distribution to build your own Embedded Linux operating system, which will contain everything you need(utilities, sources, compiler, debugger, and documentation).Here is a list of the software that can be used to make LEM: TinyLogin: TinyLogin is a suite of tiny UNIX utilities for handling logging into, being authenticated by, changing one's password for, and otherwise maintaining users and groups on an embedded system.It also provides shadow password support to enhance system security.TinyLogin is, as the name implies, very small, and makes an excellent complement to BusyBox on an embedded System.BusyBox: BusyBox is a multicall binary used to provide a minimal subset of POSIX-style commands and specialized functions.It is geared toward the very small, such as boot floppies, embedded systems, etc.Specifically it is used in the Debian Rescue/Install system(which inspired development on the original BusyBox), the Linux Routeur Project, LEM, lineo, and others.Busybox is being maintained by Erik Andersen.Ash: Ash is a very small Bourne shell.Sysvinit: Sysvinit is the most used init package for Linux.We will use init and the C version of the start-stop-daemon.See the Resources section for more information on these items.Seven.Creating a bootdisk A bootdisk is basically a miniature, self-contained Linux system on a floppy diskette.It can perform many of the same functions that a complete full-size Linux system performs.The following material is based on the Bootdisk-HOWTO(see Resources).Step 1.Bios
All PC systems start the boot process by executing code in ROM(specifically, the BIOS)to load the sector from sector 0, cylinder 0 of the boot drive.The boot drive is usually the
first floppy drive(designated A: in DOS and /dev/fd0 in Linux).The BIOS then tries to execute this sector.On most bootable disks, sector 0, cylinder 0 contains either:
Code from a boot loader such as LILO, which locates the kernel, loads it, and The start of an operating system kernel, such as Linux executes it to start the boot proper
If a Linux kernel has been raw copied to a diskette, a hard drive, or another media, the first sector of the disk will be the first sector of the Linux kernel itself.This first sector will continue the boot process by loading the rest of the kernel from the boot device.Step 2.The boot loader
You will use a boot loader like LILO to operate the boot process.It allows the development and production platforms to co-exist on the same hardware and permits switching from one to the other just by rebooting.The LILO boot loader is loaded by the bios.It then loads kernels or the boot sectors of other operating systems.It also provides a simple command line interface to interactively select the item to boot with its options.See Resources for more information on LILO.Step 3.The kernel
The kernel checks the hardware and mounts the root device and then looks for the init program on the root filesystem and executes it.Step 4.Init Init is the parent of all other processes that will run on your Linux OS.It will watch its child processes and start, stop, re-launch them if needed.Init takes all information from /etc/inittab.Step 5.Inittab The file /etc/inittab/ refers to scripts named /etc/rc...to do the system setup.It also has entries for the getty tool to handle the login process.Step 6.The login process
There is one getty available in the inittab file for each console allowed for the users.Getty will launch /bin/login to verify the user password.Step 7.Creating a new partition
From the LFS-HOWTO(see Resources): Before we can build our new Linux system, we need to have an empty Linux partition on which we can build our new system.If you already have a Linux Native partition available, you can skip this step and the following one.Start the fdisk program(or cfdisk if you prefer that program)with the appropriate hard disk as the option(like /dev/hda if you want to create a new partition on the primary
master IDE disk).Create a Linux Native partition, write the partition table, and exit the(c)fdisk program.If you get the message that you need to reboot your system to ensure that the partition table is updated, then please reboot your system now before continuing.Step 8.Creating an ext2 file system on the new partition
From the LFS-HOWTO(see Resources): To create a new ext2 file system we use the mke2fs command.Give $LFS as the only option, and the file system will be created.From now on I'll refer to this newly created partition as $EMBPART.$EMBPART should be substituted with the partition you have created.Step 9.Mounting the partition
To access the newly created filesystem, you have to mount it.To do this, create an /mnt/hda? directory and type the following at the shell prompt:
mkdir /mnt/hda? mount $EMBPART /mnt/hda? If you created your partition on /dev/hda4 and you mounted it on /mnt/hda4, then you'll need to return to the step where you copied a file to $dollar;EMBPART/usr/sbin, and copy that file to /mnt/hda4/usr/bin.Do this after the last command in Step 14(Copy the file in $EMBPART/usr/sbin).Step 10.Populating the filesystem
The root filesystem must contain everything needed to support a full Linux system.We will build a directory structure not that far from the File Hierarchy Standard(see Resources).Step 11.Directories The mkdir function in the new mounted filesystem creates the following directories: /proc
Directory stub required by the proc filesystem /etc :System configuration file /sbin :Critical System binaries
/bin :Basic binaries considered part of the system /lib :Shared Libraries to provide run-time support /mnt :Mount point for maintenance /usr :Additional utilities and applications
cd /mnt/hda?
mkdir bin dev home proc sbin usr boot etc liv mnt root tmp var mkdir-p usr/bin usr/sbin usr/share usr/lib mkdir-p etc/config etc/default etc/init.d etc/rc.boot
mkdir-p etc/rc0.d etc/rc1.d etc/rc2.d etc/rc3.d etc/rc4.d etc/rc5.d etc/rc6.d etc/rcS.d
/dev :The dev directory is the stub required to perform devices input / output.Each file in this directory may be created using the mknod function.You may save time by directly copying the required dev entries from your desktop Linux, using the following instruction: cp-dpR /dev /mnt Eight.Installing TinyLogin and login dependencies TinyLogin(see the Resources section to install it)will give us the following tools in less than 35Kb:
/bin/addgroup, /bin/adduser, /bin/delgroup, /bin/deluser, /bin/login, /bin/su, /sbin/getty, /sbin/sulogin, /usr/bin/passwd.Please refer to your main distribution doc or man pages for a full description of those commands.Step 12.Configuring TinyLogin
From the TinyLogin README: TinyLogin is modularized to help you build only the components you need, thereby reducing binary size.To turn off unwanted TinyLogin components, simply edit the file tinylogin.def.h and comment out the parts you do not want using C style(//)comments.Step 13.Installing TinyLogin After the build is complete, a tinylogin.links file is generated, which is then used by make install to create symlinks to the tinylogin binary for all compiled-in functions.By default, make install will place a symlink forest into pwd /_install unless you have defined the PREFIX environment variable.Step 14.Installing Sysvinit and start-stop daemon
After the kernel is done loading, it tries to run the init program to finalize the boot process.Now: 1.Unpack the Sysvinit archive 2.Go to the src directory
3.Copy the init executable in $EMBPART/sbin
The Sysvinit package also offers a C version of the start-stop-daemon in the contrib directory.1.Compile it
2.Copy the file in $EMBPART/usr/sbin Step 15.Configuring Sysvinit
Sysvinit needs a configuration file named inittab, which should be placed in $EMBPART/etc.Here is the one used in the LEM distribution: # /etc/inittab: init(8)configuration.# $Id: inittab,v 1.6 1997/01/30 15:03:55 miquels Exp $ # Modified for LEM 2/99 by Sebastien HUET # default rl.id:2:initdefault: # first except in emergency(-b)mode.si::sysinit:/etc/init.d/rcS # single-user mode.~~:S:wait:/sbin/sulogin # /etc/init.d executes the S and K scripts upon change # 0:halt 1:single-user 2-5:multi-user(5 may be X with xdm or other)6:reboot.l0:0:wait:/etc/init.d/rc 0 l1:1:wait:/etc/init.d/rc 1 l2:2:wait:/etc/init.d/rc 2 l3:3:wait:/etc/init.d/rc 3 l4:4:wait:/etc/init.d/rc 4 l5:5:wait:/etc/init.d/rc 5 l6:6:wait:/etc/init.d/rc 6 # CTRL-ALT-DEL pressed.ca:12345:ctrlaltdel:/sbin/shutdown-t1-r now # Action on special keypress(ALT-UpArrow).kb::kbrequest:/bin/echo “Keyboard Request--edit /etc/inittab to let this work.” # /sbin/mingetty invocations for runlevels.1:2345:respawn:/sbin/getty 9600 tty1 2:23:respawn:/sbin/getty 9600 tty2 #3:23:respawn:/sbin/getty tty3 #you may add console there #4:23:respawn:/sbin/getty tty4 Step 16.Creating initial boot scripts
As seen in the inittab file, Sysvinit needs additional scripts in its own directories.Step 17.Creating the necessary directories and base files
Use the following command to create the directories: cd $EMBPART/etc mkdir rc0.d rc1.d rc2.d rc3.d rc4.d rc5.d rc6.d init.d rcS.d rc.boot Go to the unpacked Sysvinit source directory Copy the debian/etc/init.d/rc to:$EMBART/etc/init.d Go to the $EMBPART/etc/init.d/ Create a new file rcS like those in LEM: #!/bin/sh PATH=/sbin:/bin:/usr/sbin:/usr/bin runlevel=S prevlevel=N umask 022 export PATH runlevel prevlevel /etc/default/rcS export VERBOSE # Trap CTRL-C only in this shell so we can interrupt subprocesses.trap “:” 2 3 20 # Call all parts in order.for i in /etc/rcS.d/S??* do
[!-f “$i” ] && continue
case “$i” in
*.sh)
（trap-2 3 20
.$i start)
;;
*)
$i start
;;
esac done # run the files in /etc/rc.boot [-d /etc/rc.boot ] && run-parts /etc/rc.boot
Copy run-parts from your distro to $EMBPART/bin.Step 18.Adding base scripts
A lot of the commands being used here are UNIX/Linux commands that set, export, etc.paths that are embedded inside of a UNIX shell script. Create a new file reboot containing the following: #!/bin/sh PATH=/sbin:/bin:/usr/sbin:/usr/bin echo-n “Rebooting...” reboot-d-f-i Create a new file halt containing the following: #!/bin/sh PATH=/sbin:/bin:/usr/sbin:/usr/bin halt-d-f-i-p
Nine.Summary The Linux operating system has a very bright future in the area of embedded applications for anything from Internet appliances to dedicated control systems.Roughly 95% of all newly manufactured microcomputer chips are used for embedded applications.The power, reliability, flexibility, and scalability of Linux, combined with its support for a multitude of microprocessor architectures, hardware devices, graphics support, and communications protocols have established Linux as an increasingly popular software platform for a vast array of projects and products.Because Linux is openly and freely available in source form, many variations and configurations of Linux and its supporting software components have evolved to meet the diverse needs of the markets and applications to which Linux is being adapted.There are small footprint versions and real-time enhanced versions.Despite the origins of Linux as a PC architecture operating system, there are now ports to numerous non-x86 CPUs, with and without memory management units, including PowerPC, ARM, MIPS, 68K, and even microcontrollers.But look out, there's more coming in the near future for many other Information Technology(IT)domains!
