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元旦标语范文1
1.牢固确立科学发展观,在科学发展中率先发展
2.汇聚百川、服务两港、创新开拓、勇立潮头
3.抢抓新机遇,增创新优势,再创新辉煌
4.装点天下商通四海,业精于勤日日高升
5.年年岁岁花不同,岁岁朝朝人依在
6.在新的一年新的开始新的起点新的征程
7.祝全体员工元旦节快乐
8.张灯结彩迎新年,齐心协力谱新篇
9.在歌声中欢度元旦,在元旦中享受歌声
10.张灯结彩欢度佳节,齐心协力共创伟业
11.城市,让生活更美好
12.坚持科学发展和谐发展,努力把南汇建设成为民富区强、文明和谐的现代化海港新城
13.建设社会主义新农村,共创南汇美好家园
14.坚持党的群众路线,全心全意为人民服务
15.新年伊始,向各行各业的建设者致敬
16.新年快乐,佳节如意!
17.迎元旦,庆新春
18.欢度春节,祝福万家
19.迎新年,讲文明,树新风,促和谐
20.以科学发展观统领全局,推动南汇经济社会又好又快发展
21.世界文明的盛会,我们大家的世博
22.祝大家新年快乐!
23.以我文明新貌,共庆新春佳节,喜迎世博盛会
24.文明的城市、欢庆的佳节,美好的生活
25.喜迎元旦佳节
26.抢抓新机遇,争创新优势,再创新辉煌
27.汇聚百川、服务两港、创新开拓、勇立潮头
28.与时俱进弘扬南汇精神,万众一心构建和谐港城
29.以党的xx大精神为指导,抓住机遇,奋发有为,开创南汇现代化事业新局面
30.聚精会神搞建设,一心一意谋发展
工厂迎新年标语:
31.张灯结彩喜迎新年齐心协力共谱新篇
32.和气吉祥岁岁安康四季平安年年如意祝大家新年快乐!
33.欢欢喜喜迎龙年,安全赢利又一年!
34.恭祝全厂员工新年快乐幸福安康如意吉祥
35.企业迎新年的标语或对联:
36.谋发展公司同仁齐心协力建旷世奇功
37.运筹帷幄雄心开创千秋业
38.达权知变妙笔描绘万代春
39.横批财源广进
40.大吉大利过新年,事业成功辉煌年!
41.年年顺景财源广岁岁平安福寿多
幼儿园迎新年标语
42.一干二净除旧习五讲四美树新风
43.春*明媚山河披锦绣华夏腾飞祖国万年轻
44.五更分两年年年称心一夜连两岁岁岁如意
公司新年横幅标语:
45.xxx公司恭贺全体员工新春愉快阖家欢乐
46.xxx公司恭祝大家新年快乐身体健康
47.XX公司祝全体员工元旦快乐!龙年大吉!
48.喜迎龙年!欢度新年!再接再励!再创辉煌!
49.公司祝各位同仁:新年好!
元旦标语范文2
guitar.吉他
sing.唱;唱歌
swim游泳
dance.跳舞;舞蹈
draw.画
chess.国际象棋
play chess 下国际象棋
speak.说;说话
speak English 说英语
join参加;加入
club.俱乐部;社团
be good at… 擅长于……
tell讲述;告诉
story故事;小说
write.写作,写字
show.演出;表演展示
or conj.或者
talk说话;谈话
talk to … 跟……说
kungfu(中国)功夫
drum鼓
play the drums 敲鼓
piano.钢琴
play the piano 弹钢琴
violin小提琴
play the violin 拉小提琴
also adv也;而且
people人;人们 home 家,活动本部
adv到家;在家
be good with… 善于应付……的;对……有办法
make使成为;制造
make friends 结交朋友
today adv.在今天
help with在某方面帮助(某人)
center(=centre)中心,中央
weekend.周末
on the weekend. (在)周末
teach教,讲授
musician音乐家
Lisa 莉萨(女名)
元旦标语范文3
关键词:标准单点定位;数据处理;精密星历;钟差
中图分类号: N37 文献标识码: A 文章编号:
GPS自投入使用以来,正向着实时、高精度、高可靠性的方向发展。在GPS应用中,通常采用相对定位的作业模式, GPS技术的不断发展,相对定位作业模式被发现存在一些不足,随着各种研究的不断深入,产生了一种解决这些不足的方法,即GPS精密单点定位技术,它可以利用单台接收机在全球范围内进行高精度的独立的静态或者动态定位,利用卫星星历及卫星钟差,以单台双频接收机采集的非差相位和伪距数据作为主要观测值来进行单点定位,可以直接得到分米级甚至厘米级的高精度的ITRF框架标。
一、GPS标准单点定位的基本原理
伪距单点定位是利用测码伪距观测值以及由广播星历提供的卫星轨道参数和卫星钟改正数来独立确定单测站的绝对位置的定位方法,它具有速度快,数据处理简单等优点,其精度也足以满足部分用户的需要,是导航及低精度测量中所用的一种定位方法。本文以伪距单点定位为基础研究了电离层与对流层误差模型。
利用单点定位方法进行动态定位时,由于每个载置只能进行一次观测,故精度较低,但可以通过平滑或滤波等方法来消弱噪声,提高定位精度。利用单点定位方法进行静态定位时,由于点位可反复测定,当观测时间较长时可提高定位精度。
二、GPS标准单点定位的主要误差源及改正模型
1.电离层延迟
电离层延迟是GPS点定位中的一种重要误差源,也是致使差分GPS系统的定位精度随流动站和基准站间距增加而迅速下降的主要原因之一。地球高层大气的分子和原子在太阳的紫外线,X射线和高能粒子的作用下电离,产生自由电子和和正负离子,形成从宏观上说仍然是中性的等离子体区域,称为电离层(刘经南,1999)。由于存在大量的自由电子和正负离子,当卫星信号穿过电离层时,如同其他电磁波一样,信号的路径会发生弯曲,传播速度也会发生变化,从而使得测量所得到的距离就会不等于卫星至接收机间的几何距离,这种偏差叫电离层折射误差。
2.对流层延迟
对流层一般泛指非电离大气对电磁波的折射。非电离大气包括对流层和平流层,是高度为50km以下的大气层部分。对流层靠近地表面,容易从地面获得辐射能量,使其温度随高度的上升而降低,当GPS或GLONASS卫星信号通过对流层时,传播的路径会发生弯曲,从而使测量的距离产生偏差,这种偏差叫对流层折射误差。对流层的折射率在很大程度上受到大气压力、温度和湿度的影响。在大气正常状态下,天顶方向干分量延迟约占整个对流层延迟的90%。湿分量的影响比干分量的影响要小得多,约占整个流层误差的10%。由于对流层折射对GPS和GLONASS信号传播的影响情况比较复杂,一般采用对流层误差改正模型来进行减弱。对流层改正模型通常是对天顶方向的对流层干湿分量分别进行建模,然后使用一个投影函数将其投影到卫星与测站连线的方向上。
3.多路径
在GPS或GLONASS测量中,如果测站周围的反射物所反射的卫星信号(反射波)进入接收机天线,这将和直接来自卫星的信号(直接波)产生干涉,从而使观测值偏离真值,这种由于反射信号所引起的观测值误差叫多路径误差。理论上,对测码伪距而言多路径误差最大为近似码长的一半,也就是对GPS C/A码的多路径误差最大可达150m,对P(Y)码的多路径误差最大可达15m。削弱多路径的方法有很多,大致可分为以下几种:
1) 选择合适的站址。在选择测站时,应远离大面积平静的水面,远离高层建筑物,测站也不宜选择在山坡、山谷和盆地中。灌木丛、草、其它地面植被、翻耕后的土地以及其他粗糙不平的地面能较好的吸收微波信号的能量,是较为理想的设站地址。
2) 选择合适的天线。选择能抑制多路径的高质量的天线。为了减弱多路径误差,天线下应配置抑径板或者选择扼流圈(choke-ring)天线。
3) 选择合适的接收机。选择能抑制多路径效应影响的接收机,例如选择采用窄相关技术的接收机。
4) 通过估计方法减轻多路径误差。在计算时,过滤掉低高度角卫星的观测数据,因为低高度角的卫星信号更容易产生多路径效应。在利用测码伪距观测值进行定位时,使用长时间的观测数据,对定位结果进行平滑处理,也可以有效的减弱多路径效应的影响。另外通过一些估计方法像半参数法等也可以减弱多路径误差的影响。
4.卫星轨道和钟误差
卫星轨道误差是指卫星星历所表示的卫星轨道和真正的卫星轨道之间的偏差值。轨道误差主要受到跟踪网的规模、跟踪方法、跟踪站的分布、以及轨道计算的数学模型等因素影响。卫星星历用来提供卫星运动轨道的信息。它可以分为预报星历和后处理星历。预报星历又叫广播星历,它是由地面监控站根据对卫星跟踪测得的轨道外推计算得到的。由于受到诸如跟踪站站址坐标误差,观测误差,计算模型误差,预报误差等各种误差的影响,广播星历也不可避免存在误差。卫星钟的钟差包括由钟差、频偏和频漂等产生的误差,也包含了钟的随机误差。在GPS测量中,无论是码相位观测或载波相位观测,均要求卫星钟和接收机钟保持严格同步。尽管GPS卫星上安装有高精度的原子钟(铷钟和铯钟),但与GPS系统时间之间还是存在着偏差和漂移。这些偏差的总量在1ms以内,由此引起的等效距离误差约为300km。
5.接收机钟差
GPS接收机一般采用高精度的石英钟,其稳定度约为10-9。若接收机与卫星钟间同步差为1μs,其等效距离约为300m。接收机钟差可用下面的方法进行处理:利用单点定位的方式,把每个观测历元接收机钟差当作一个独立的未知参数,估计参数有接收机钟差和测站坐标,在数据处理中一并求解;认为各观测时刻的接收机钟差之间是相关的,将接收机钟差表示为时间多项式,并在观测量的平差计算中求解多项式的系数。同时,也可以作为白噪声处理,白噪声比多项式更为逼真地描写钟差行为;通过在卫星间求一次差来消除接收机的钟差。即在每一个历元,选一颗卫星为参考星,其它卫星与参考星进行卫星间观测值相减作一次差分。
总之,标准单点定位是目前GPS界的一个研究热点,本文围绕标准单点定位的数据处理这一中心,对标准单点定位的主要误差源和改正模型进行了一定的研究。计算结果表明,标准单点定位精度为米级,气解算可满足对导航定位精度要求不高的一般用户需要,若对一些其他误差加以考虑,则可以进一步提高定位精度。
参考文献:
[1] 乔仰文,赵长胜,夏春林等.GPS卫星定位原理及其在测绘中的应用[M].教育科学出版社,2003.
元旦标语范文4
关键词:凋亡蛋白质;原核表达;可溶性;纯化;稳定性
中图分类号:Q786文献标识码:A文章编号:1672-979X(2008)03-0007-05
Expression, Purification and Activity Detection in vitro of Apoptin
FU Wen-bing1, SHI Xuan1, ZHAO Jian1*, FAN Li-qiang1, LI Su-xia, WANG Fu-jun2, SONG Yu-wen1, YUAN Qing-sheng1
(1. State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China; 2. Zhejiang Rishengchang Pharmaceutical Co., Ltd, Zhejiang 322100, China)
Abstract :Objective To construct an soluble expression system in E. coli for apoptin which was encoded by VP3 gene of chicken anemia virus (CAV), and study the purification and stabilization of apoptin. Methods The VP3 gene was amplified by PCR , then the segment was inserted into pET-28a (+) and the expression vector pET-28a-VP3 was constructed in E. coli BL21(DE3). The recombinant soluble protein was expressed in E. coli BL21(DE3)and purified by Ni-NTA column chromatography. The stability of apoptin was analyzed under different conditions. Results The target protein was expressed in E. coli BL21(DE3). The purity of apoptin was beyond 90 %after purification. The target protein was better stabilized by carrageenan in E.coli BL21(DE3). Conclusion Apoptin with high purity and stability can be successfully obtained, which do a base of the further study on clinic application of apoptin.
Key words:apoptin; prokaryotic expression; solubility; purification; stability
凋亡蛋白质是鸡贫血病毒(CAV)的VP3基因编码的小分子蛋白质,由121个氨基酸组成,含有2个脯氨酸富含区和2个碱性区,近N端(33~44a)含有一个11个氨基酸组成的核运输序列(NES),靠近C端(84~90,112~118)含有2个核定位序列(NLS)。
Noteborn等[1]研究揭示,凋亡蛋白质能够诱导人的肝癌、淋巴瘤、白血病、乳腺癌、肺癌等多种癌细胞的凋亡,以及转化细胞的凋亡,但对未转化的人双倍体细胞无损伤[2]。凋亡蛋白质的核定位可能是其诱发细胞凋亡的前提之一[3]。凋亡蛋白质选择性诱导肿瘤细胞的凋亡不同于通常的凋亡机制,它不是通过半胱天冬酶级联反应进行的,不需要p53参与,也不被bcl-2的过表达抑制,反而能被bcl-2所促进[4]。由于大部分肿瘤细胞具有p53突变或缺失,这种非p53依赖性使凋亡蛋白质作为抗肿瘤药物有很好的前景。
在许多关于凋亡蛋白质表达和纯化的研究中,凋亡蛋白质多以包涵体形式表达。本实验以pET-28a为载体进行凋亡蛋白质的原核表达,尝试不同的诱导条件及纯化方法,找到了可溶性目的蛋白质表达的条件,用金属螯合层析法直接纯化得到较高得率的活性目的蛋白质,并研究其稳定性。本研究对凋亡蛋白质作为肿瘤治疗药物应用于临床具有积极意义。
1材料和方法
1.1质粒、菌株和试剂
含有凋亡蛋白质全长基因的质粒pET-11a-VP3(浙江日升昌药业有限公司提供);质粒pET-28a和菌株BL21(DE3)等(本实验室保存);低相对分子质量蛋白质和DNA Mark(Sigma公司);IPTG(异丙基-β-D-硫代半乳糖苷)(BBI分装);SDS(十二烷基磺酸钠)(Amresco分装);限制性内切酶、T4-连接酶、Taq酶(MBI公司);其它化学试剂均为国产分析纯。
1.2原核表达重组质粒的构建
VP3基因来源于pET-11a-VP3质粒。PCR引物分别为P1:5’-AATTTCAAC ATATGAACG CTCTCCAAG-3’;P2:5’- CGTCGGATCCTATT ACAGTCTTATACGC-3’。分别引入NdeI和BamHI位点。PCR产物经NdeI和BamHI双酶切后,回收的VP3基因片段与经同样双酶切的质粒pET-28a连接和转化。抽提质粒,用BamHI和NdeI对重组质粒进行双酶切鉴定得到阳性重组质粒。
1.3凋亡蛋白质的原核表达及纯化
1.3.1凋亡蛋白质的表达与鉴定将含有重组质粒pET-28a-VP3的BL21(DE3)菌株接种于LB培养基中,37 ℃培养过夜,次日按1∶100的比例稀释后放大培养,至一定菌体浓度时,加入适量IPTG诱导培养,离心收集菌体。
SDS-PAGE分析 12 % SDS-PAGE电泳,电压100 V,待样品即将进入分离胶时,调节至120 V。电泳后凝胶用考马斯亮蓝溶液(45 %甲醇,10 %乙酸,0.25 %考马斯亮蓝R 250)染色。
1.3.2可溶性目的蛋白质的纯化将新鲜菌体按1∶5(W∶V)的比例用Tris-HCl缓冲液(10 mmol/L Tris-HCl,10 %甘油,pH 8.5)重悬,保持在冰浴中,超声破碎至菌液澄清。4 ℃,10 000×g离心20 min,取上清,Ni-NTA Agarose 金属亲和树脂(Qiagen公司)分离纯化。将上清液加入经Tris-HCl缓冲液平衡的Ni-NTA 介质中,4 ℃结合60 min。将混合物小心加入下端封闭的层析柱后,除去下端封盖,收集流出液(穿出峰)。以15 mL含20 mmol/L咪唑的磷酸缓冲液漂洗后,再分别以15 mL含40,60,100,200 mmol/L咪唑的磷酸缓冲液洗脱目的蛋白质。分别收集洗脱组分,进行SDS-PAGE鉴定,Bradford法测定蛋白质浓度,凝胶扫描软件分析纯度。
1.4凋亡蛋白质溶液稳定性研究
将重组表达的凋亡蛋白质于4 ℃放置3 d后,取样进行SDS-PAGE电泳鉴定,对照3 d前样品观察凋亡蛋白质在溶液状态中的稳定性。通过改变离子强度(增加NaCl浓度)和添加不同稳定剂来增加凋亡蛋白质的稳定性。
2结果
2.1重组表达质粒的构建
以pET-11a-VP3为模板扩增PCR,得到预期大小的目的片断。切胶回收后双酶切(BamHI+NdeI),酶切产物与同样双酶切的pET28a连接。连接产物转化E.coli DH5α,用BamHI和NdeI双酶切鉴定重组质粒(见图1),得到了含有400 bp目的片段的阳性克隆,与预期结果相同。经上海生工生物公司测序验证构建好的pET-28a-VP3,序列正确,并使凋亡蛋白质的N端带有His-Tag,为目标蛋白质的纯化提供了条件。
2.2重组蛋白质的表达
为了提高重组蛋白质的表达量,本实验研究了IPTG的浓度。当菌体密度到达约A600 0.6时,加入IPTG至终浓度分别为0.2,0.5,1 mmol/L,30 ℃诱导表达5 h,见图3。
由图3可见,经1 mmol/L IPTG诱导后表达量较高,目标蛋白质相对分子质量约16×103,与预期大小一致。
2.3可溶性凋亡蛋白质的纯化
诱导表达后菌体破碎离心,上清液用目的蛋白质N端的6×His咪唑基团与镍离子特异性结合,金属螯合层析法分离纯化,得到较纯的目的条带。经SDS-PAGE电泳扫描分析,纯度高于90 % ,见图4。蛋白质浓度测定表明每克湿菌体可以到0.49 mg凋亡蛋白质。
2.4凋亡蛋白质的稳定性研究
实验中发现凋亡蛋白质在溶液中不稳定,极易沉淀。实验中分别取IPTG诱导后样品立即进行SDS-PAGE分析,第3天再进行1次SDS-PAGE分析,见图5-A、5-B。
1. 低相对分子质量标准蛋白; 2,3. 放置2 d后目标蛋白质
图5-A. 诱导的菌体取样后立即SDS-PAGE,1和2 皆为目标蛋白质;图5-B. 诱导的菌体2 d后SDS-PAGE
图5 凋亡蛋白质SDS-PAGE稳定性分析
图5-A. 诱导的菌体取样后立即SDS-PAGE,1和2 皆为目标蛋白质;图5-B. 诱导的菌体2 d后SDS-PAGE
诱导的菌体取样后立即SDS-PAGE分析,可以看到目的蛋白质的表达条带清晰;2 d后SDS-PAGE分析,几乎观察不到目的蛋白质条带,推测凋亡蛋白质随着储存时间延长发生了聚合。这说明可溶性表达的凋亡蛋白质在溶液状态中易形成沉淀,一般2~3 d就发生大量聚集。因此有必要进行可溶性蛋白质的稳定性研究。
将表达得到的目的蛋白质分别保存于高、中、低3种不同盐浓度的缓冲液中,观察其稳定性。低盐溶液:20 mmol/L Tris.HCl缓冲液;中盐溶液:80 mmol/L NaCl、20 mmol/L Tris.HCl;高盐溶液:300 mmol/L NaCl、20 mmol/L Tris.HCl。pH值均为8.0。
实验表明,凋亡蛋白质在低盐溶液中不稳定,在超滤过程中即有大量沉淀析出。分别取高盐溶液和中盐溶液中4 ℃保存48 h前、后的样品,分析上清蛋白质浓度。2次重复实验结果表明,高盐蛋白质浓度平均降低16 %,中盐溶液中平均降低34 %。推测高盐环境更有利于凋亡蛋白质的稳定。
进一步研究,于缓冲液中加入各种稳定剂(最终浓度0.1 %):阿拉伯树胶、卡拉胶、瓜豆尔胶、CMC(羧甲基纤维素钠)、明胶、高酯果胶、魔芋胶、黄原胶等,观察是否有利于重组凋亡蛋白质的稳定性。以上样品4 ℃保存7 d后离心得到的上清经SDS-PAGE分析,结果见图6。
1. 对照;2. 阿拉伯树胶;3. 卡拉胶;4. 瓜豆尔胶5.CMC;M. 低相对分子质量标准蛋白质;6. 明胶;7. 高酯果胶;8. 魔芋胶;9. 黄原胶
图6 添加剂对凋亡蛋白质稳定性的作用分析
图5-A. 诱导的菌体取样后立即SDS-PAGE,1和2 皆为目标蛋白质;图5-B. 诱导的菌体2 d后SDS-PAGE
实验结果表明,在高盐缓冲液中加入卡拉胶,目标蛋白质几乎没有沉淀,卡拉胶可以有效增强可溶性蛋白质的稳定性。
3讨论
本实验构建了表达质粒pET-28a-VP3,并在E. coli BL21(DE3) 中获得表达,用Ni-NTA柱纯化目标蛋白质。由于稀有密码子占VP3基因氨基酸序列组成的25 %左右,为了提高表达量,本实验选用严紧型表达宿主菌BL21(DE3)pLysS及促进富含稀有密码子的基因表达的Rosetta菌株表达目的蛋白质。实验结果(数据未列出)表明,Rosetta菌株中目的蛋白质的表达量并未增加,说明稀有密码子不是限制其表达量提高的因素。BL21(DE3)pLysS目的蛋白质的表达量也没有明显变化,表明目标产物对细胞无毒性或毒性很小。由于凋亡蛋白质稳定性差,其稳定性对于其临床应用至关重要。本实验通过改变溶液的离子强度及添加稳定剂来增加目标蛋白质的稳定性[5],高盐缓冲液中加入卡拉胶可以有效增强凋亡蛋白质的稳定性[6]。本实验为在原核生物中进行目标蛋白质的表达和分离纯化,以及稳定性研究提供了简易可行的途径,为凋亡蛋白质的进一步药理研究奠定了基础。
参考文献
[1]Noteborn H M, Danen-van Oorschot A A, Vandereb A J. The apoptin gene of chicken anemia virus in the induction of apoptosis in human tumorigenic cells and in gene therapy of cancer[J]. In:Boulikas T. ed. Gene Ther Mol Biol. 1998: 399-406
[2]Danen-van Oorschot A A, Fisher D F, Grimbergen J M, et al. Apoptin induces apoptosis in human transformed and m alignant cells but not in normal cells[J]. Proc Natl Acad Sci USA, 1997, 94 (11): 5834.
[3]Zhang Y H, Abrahams P J, Vandereb A J, et al. The viral protein apoptin induces apoptosis in UV-C- irradiated cells from individuals with various hereditary cancer- prone syndromes[J]. Cancer Res, 1999, 59 (12): 3010-3015.
[4]Noteborn M H, Zhang Y H, Vandereb A J. Apoptin specifically causes apoptosis in tumor cell and after UV-treatment in untransformed cells from cancer-pron individuals: areview[J]. Mutat Res, 1998, 400(1-2): 447.
元旦标语范文5
关键词 跳表示;滤波电路;滤波电容;雷击
中图分类号:U262 文献标识码:A 文章编号:1671-7597(2014)13-0183-01
道岔控制表示单元是铁路信号微机联锁系统的重要元器件,在道岔控制电路中起着控制道岔转换、锁闭和给出表示的作用,其运行的可靠性直接影响信号系统的可靠性和安全性。每一组道岔均对应一台控制表示单元,山钢集团莱芜分公司运输部6套微机联锁系统,共应用控制表示单元310台。在设备维护中我们发现,道岔控制表示单元常出现的故障有“跳表示”和雷击两种,占总故障的80%以上。为保障设备的稳定运行,降低故障率,同时做好设备修旧利废工作,使故障的元器件得到重新利用,我们对其进行深入分析和研究。
1 表示电路原理分析
道岔控制表示单元电路分三部分,控制电路、转换锁闭电路和表示电路。三部分电路除共用电源外,电路部分彼此独立,工作状态互不影响。“跳表示”故障发生在表示电路,雷击故障大多数只击坏表示电路,故对表示电路进行深入分析。
道岔表示电路原理图如图1。
图1 道岔表示电路原理图
由图可以看出,此电路由上下对称两部分组成,下半部分为定位表示电路,上半部分为反位表示电路,电源由53输入,道岔在定位时,53、63有30 V的交流表示电源,在反位时53、51有30 V的交流表示电源,两路电源分别通过两个滤波电路,分别给光耦TLP521-2和固态继电器K2提供电源。工作正常时,定位表示电由62输出,反位表示电由52输出。
当道岔处在定位时,30 V的交流表示电由53、63输入后,经过D4和D26单相整流,和C2、C20的电容滤波,原来的交流电变成直流供下一级电路使用。D26和C20整流滤波后,24V直流电送到K2继电器线圈两端,K2得电吸起;D4和C2整流滤波后的6V电源送到光耦TLP521-2工作,经过电阻R4分压后,1、2端电压1.2 V左右,使内部发光二极管导通发光,内部三极管7、8耦合导通,使KZ24V电源经过继电器K2的9、13和K1的6、4接点到达62,经62输出到微机联锁主机,使主机能够辨识定位表示,通过显示器显示。
当道岔处在反位时,原理与定位相同。
2 故障原因分析与处理
1)“跳表示”故障。经过以上电路分析,表示电路的正常工作与滤波电路、光耦TLP521-2及固态继电器的性能有关。用万用表反复测量,确定光耦TLP521-2、OMRON24V固态继电器及周围电阻电容等元件均状态良好,无烧损、短路或断路情况。查找光耦TLP521-2参数资料,其输入端典型工作电压和转换电流为5V 16 mA,最大25 mA。D3、D4为1N4735A,1W6.2V稳压二极管,R4、R5由以下公式确定其阻值:
R=(U-U二极管×3)/I =(6.2-0.7×3)/0.016≈256 Ω
由色标确认R4、R5阻值为220Ω,接近256Ω。使用220 Ω电阻时,电路中电流为:
I=(U-U二极管×3)/ R=(6.2-0.7×3)/220=0.0164=16.4 mA
电路中电流接近典型值,因此,R4、R5电阻选择适当。
故障的发生还可能与滤波电路的设计有关,则内部三极管7、8导通不正常,而控制光耦TLP521-2耦合导通的电源来自前级的滤波电容和稳压二极管C2、 D4和C1、D3,滤波电容C1和C2容量的大小与充放电能力直接影响光耦内二极管的导通,从而也间接影响了三极管的导通,故障原因可能出现在与滤波电容的选择上,于是重新核算C1、C2电容容量。
在滤波电路中电容的选择应遵循以下公式:
C≥(3-5)T/2R
R为电路负载电阻,R≈R4=R5=220 Ω
T为50 Hz工频电路,T=1/50=0.02 s
经计算得出:C≥136-227uf
因此,原来应用的100uf的电容容量太低,长时间使用后,容量还会下降,滤波电压不稳定,进而造成供给光耦输入端的电压不稳定,当二极管发光较弱时,三极管不能导通。输出端电压不稳定,经过其导通输出的KZ24V电压时有时无,就造成道岔表示的闪烁,形成了道岔“跳表示”故障。
在滤波电容C的选择上,容量应越大越好,越大输出电压的波形变得更为平滑、起伏更小,滤波电压更稳定,但在电路接通瞬间,电路中所产生的冲击电流太大,对电路中其它元器件会造成损坏。因此,C1,C2选择容量220uf耐压值25 V的电解电容即可。
基于以上原因分析,我们对故障的18台道岔控制表示单元进行了维修,将C1、C2均更换为220uf的大容量电容,更换后贴好标签,做好标记,送信号楼微机联锁道岔柜进行应用试验,重点监督运行状态,使用一个月未再发生“跳表示”故障,由此断定,原因分析和解决措施是正确的。以后陆续对同批次的道岔控制表示单元电容进行了更换,“跳表示”故障未在出现。
2)雷击故障。通过对十几台被雷击的道岔控制表示单元的研究分析发现,多数都是击坏表示电路元件,雷电沿道岔控制线X3进入设备内部,击坏元件如下:①击坏光电耦合器521-2P,输入端二极管短路,外壳崩裂,元件无法再用;②击坏整流滤波元件D3、D25或D4、D26,二极管短路,光电耦合器521-2P没有输入电源,不能工作;③击坏R5、D5,光电耦合器前级电阻和定、反位表示灯,电路无法工作,无法给出表示。
我们对雷击损坏的元器件进行了更换,对修复的控制表示单元进行综合电气参数测试后,送信号楼在道岔机柜上进行应用试验,确认合格后贴标签备用。
3 结束语
“跳表示”故障的发生与厂家供应的设备质量有关,为此对同批次所有控制表示单元进行了检查,对所有C1、C2使用小容量的控制表示单元进行了更换,与厂家联系退回,协商赔偿损失。同时联系厂家对设备设计、安装及元器件应用进行再检查,防止此类问题发生。
同时探索在道岔控制电路X3中加装雷电防护装置,当雷电发生时进行有效的隔离和放电,防止雷电窜入击坏设备。
元旦标语范文6
1.I’m sorry I’m busy now.If I have time,I________to the zoo with you.
A.would go B.will go
C.am going D.went
2.I can’t send an e-mail.Would you please show me_______?
A.what to do it B.where to do
C.when to do D.how to do it
3.The rest of the students________not allowed to leave the classroom at that time.
A.are B.is C.were D.was
4.I don’t know whom the watch_______.
A.belongs B.belongs to
C.does it belong to D.does it belong
5.―Is this basketball Tom’s?
―It________be his because his name is on the ball.
A.can B.can’t C.must D.mustn’t
6.Unluckily,he________his stick in the relay race.
A.afforded B.realized C.felt D.dropped
7.The man pretended________anything about what was happening on the spot.
A.didn’t know B.doesn’t know
C.not knowing D.not to know
8.There is________rain here and it’s________cool this summer.
A.too much;much too B.much too;too much
C.too much;too much D.much too;much too
9.Though they are twins,they are not always________each other.
A.agree with B.in agreement
C.agreement with D.in agreement with
10.What Jack said made them_______.
A.angry B.to be angry
C.are angry D.to angry
Ⅱ.完形填空(10分)
Food is very important.Everyone needs to __1__ well if he or she wants to have a strong body.Our minds also need a kind of food.This kind of food is __2__.We begin to get knowledge even when we are very young.Small children are __3__ in everything around them.They learn
__4__ while they are watching and listening.When they are getting older,they begin to __5__ story books,science books...anything they like.When they find something new,they love to ask questions and __6__ to find out the answers.
What is the best __7__ to get knowledge? If we learn __8__ ourselves,we will get very very much knowledge.If we are __9__ getting answers from others and do not ask why,we will never learn well.When we study in the right way,we will learn more and understand __10__.
1.A.sleep B.read C.drink D.eat
2.A.sport B.exercise C.knowledge D.meat
3.A.interested B.interesting C.weak D.better
4.A.everything B.something C.nothing D.anything
5.A.lend B.read C.learn D.write
6.A.try B.have C.think D.wait
7.A.place B.school C.way D.road
8.A.on B.with C.to D.by
9.A.seldom B.always C.usually D.sometimes
10.A.harder B.much C.better D.well
Ⅲ.阅读理解(20分)
(A)
My father woke me up early one summer morning when I was fourteen and told me,“Get up.You’re going with me to cut grass in the garden.”
The idea that my father thought I was old enough to help him in his business made me feel proud and excited.From sunup to sundown,my father,my younger brother and I worked in the large garden.By the end of the day I was too tired to say a word but I felt good.This was my first time to help my father in his business.I got $ 6 for my work that day.
One day my father found some leaves I had missed and pulled me aside.“Take away these leaves!” he said,“and don’t make me have to tell you to do it again.” The message was clear.Today I value(珍视) the importance of doing a job well for the first time.It will never fail to impress(给……留下印象) the person you are working for.
Two years later,my father told my brother and me that he felt we were old enough to cut the grass by ourselves.Every Saturday during my last two years of high school,we set off early in the morning with the same strong wish we had gained while working under our father.
Looking after the garden was neither exciting nor high-paid,but that didn’t matter.It taught me that any job was a good job and that whatever I was paid was more than I had before.
A newspaper reporter once asked me how someone could possibly live with hard work and low pay.“If you’re only thinking about hard work and money,you probably don’t want to do any better than you are doing,” I answered.In every job,from cutting the grass to washing dishes,I’ve learned much.I’ve learned something that helps me in my next jo B.
If you work hard enough,you can learn from any job you do.
1.The writer felt proud and excited when he was asked to cut the grass because he thought_______.
A.he could cut the grass himself
B.he could make much money
C.he could enjoy sunup and sundown
D.he could help his family
2.The underlined word “message” in Paragraph 3 probably refers to(指)_______.
A.not leaving leaves behind
B.giving no excuse for your mistakes
C.doing a good job at the very beginning
D.missing things which can be found out
3.When the writer finished high school,maybe he was________years old.
A.fourteen B.eighteen C.twenty D.twenty-two
4.Which of the following does the writer probably think is the most important?
A.Keeping learning from any job you had.
B.Asking no money for work.
C.Finishing work as quickly as possible.
D.Keeping looking for different jobs.
5.The writer probably thinks his father is_______.
A.lazy B.helpful C.careless D.funny
(B)
Mr Baker lived in an old and low house.His wife was blind in both eyes and the two children were very young.All his family often went hungry.He had nothing but a small piece of field.One autumn he grew some wheat in his field.He hoped it would do well because all his family would depend on it.The whole winter it often snowed.And the next spring the wheat would grow well.Mr Baker was happy.
One day,Mr Baker went to watch his wheat.To his surprise,a lot of crops were eaten up by a horse.He became angry but could not find out whose horse had eaten them.He thought the horse would go there again.So he decided to stay in his field and tried to catch the horse.
A few days later a yellow horse came into his field again and began to eat the wheat.Mr Baker ran after it quickly,with a stick in his hand.But the horse ran much faster than him.He tried his best,but couldn’t catch up with it.
The next morning,when Mr Baker was working in his field,he saw the yellow horse pulling a carriage on the road.He picked a stick up at once,ran closer to the horse and began to beat it.The driver was surprised and tried to stop him.He asked,“Why are you beating my horse?”
“It has nothing to do with you,” Mr Baker said angrily.“The beast knows why I’m beating him.”
6.What was Mr Baker?
A.A driver.B.A farmer.
C.A keeper.D.A doctor.
7.What kind of life did Mr Baker’s family live?
A.A simple life.B.A happy life.
C.A rich life.D.A poor life.
8.Mr Baker was happy at first because_______.
A.he found out the horse that ate up his wheat
B.he would soon get a good piece of field
C.his wheat was growing very well
D.his family wouldn’t grow any more wheat
9.Which of the following is TRUE?
A.The horse knew that it had done wrong.
B.The horse had nothing to do with the driver.
C.The horse belonged to the driver.
D.The horse knew whose wheat it had eaten.
10.All the following statements are true EXCEPT that_______.
A.the horse was eating his wheat when Mr Baker saw it the second time
B.Mr Baker’s family depended on the wheat
C.the drive didn’t know why Mr Baker beat his horse
D.thanks to the snow last winter,Mr Baker’s wheat was growing well the next spring
(C)
New rules and behavior standards(行为规范) for middle school students came out in March.The middle school is going to use a new way to decide who the top students are.The best students won’t only have high marks.They will also be the kids who don’t dye(染) their hair,smoke or drink.The following are some of the new rules:
Tell the truth.Have you ever copied someone else’s work on an exam? Don’t do it again! That’s not something an honest student should do.If you have played computer games for two hours in your room,don’t tell your parents you have done your homework.
Do more at school.Good students love animals and care for other people.April is the Bird-loving Month in our country.Is your school doing anything to celebrate it? You should join! That way,you can learn more about animals and how to protect them.When more people work together,it makes it more fun for everyone.Have you ever quarreled with your teammates when your basketball team lost a game? Only working together can make your team stronger.Be friendly to the people you are with.Try to think of others,not only yourself.
Be open to new ideas.Have you ever thought that people could live on the moon? Perhaps you’ll discover Earth Ⅱ someday.Don’t look down on new ideas.Everyone’s ideas are important.You should welcome them,because new ideas make life better for everyone.
Protect yourself.Has someone ever taken money from one of your classmates? Don’t let it happen to you.If you have to go home late,you should let your parents know.
Use the Internet carefully.The internet can be very useful for your studies.But some things on the Internet aren’t for kids,so try to look at web pages that are good for you.You can use the Web for fun or homework.Can’t you find any good websites for children? Here are some:
http://kids.eastday,com
http://省略
http://cycnet,com
11.The school new rules will help kids by telling them_______.
A.how they can study well
B.what they should do at school
C.what is right and what is wrong
D.how they can protect themselves
12.According to the passage,which of the following is NOT true?
A.Take care of yourself when you are out.
B.Tell the truth,even when you are wrong.
C.Keep some animals to protect them.
D.Use the Internet,but keep away from bad things.
13.The main idea of the fourth paragraph is about_______.
A.making the team stronger
B.working together with others
C.being a good friend to others
D.getting on well with others
14.Good websites for children can_______.
A.be a waste of time
B.help them with their studies
C.do homework for them
D.make life easier
15.The passage tells us how to_______.
A.be top students
B.do more at school
C.care for others.
D.use the Internet
(D)
The word “day” has two meanings.When we talk about the number of days in a year,we are using “day” to mean 24 hours.But when we talk about day and night,we are using “day” to mean the time between sunrise and sunset.Since the earth looks like a ball,the sun can shine on only half of it at a time.Always one half of the earth is having day and the other half night.A place is moved from day into night and from night into day over and over by the spinning(旋转) of the earth.At the equator(赤道) day and night are sometimes the same length(长度).They are each twelve hours long.The sun rises at 6 o’clock in the morning and sets at 6 o’clock in the evening.For six months the North Pole is tilted(倾斜) toward the sun.In those months the Northern Hemisphere(半球) gets more hours of sunlight than the Southern Hemisphere.Days are longer than nights.South of the equator nights are longer than days.For the other six months the North Pole is tilted away from the sun.Then the Southern Hemisphere gets more sunlight.Days are longer than nights.North of the equator nights are longer than days.Winter is the season of long nights.Summer is the season of long days.
16.When the Western Hemisphere is having day,the Eastern Hemisphere is having_______.
A.both day and night B.day
C.neither day nor night D.night
17.A place is moved from day into night and from night into day over and over by________of the earth.
A.the pushing B.the pulling
C.the spinning D.the passing
18.At the equator day is as long as night_______.
A.sometimes B.never C.usually D.always
19.When the North Pole is tilted toward the sun,the Northern Hemisphere gets________sunlight.
A.less B.more C.all D.no
20.When it is winter in China,______.
A.the USA is tilted toward the sun
B.the South Pole is tilted away from the sun
C.the North Pole is tilted toward the sun
D.the North Pole is tileted away from the sun
Ⅳ.词汇(15分)
A.根据句意及首字母提示,写出空白处所缺的单词。
1.You can’t leave here without p______.
2.I think Mr Li is a k_______teacher.He always has many interesting stories to tell us.
3.Mark Twain is my favorite a______.
4.Animals and plants are c______.
5.The water is very s_______with much sugar in it.
6.The population of the town has i_______very quickly.
7.As a v______,he eats only vegetables instead of meat.
B.用括号内所给单词的适当形式填空
8.I would rather watch TV at home than_______(go) to the cinema.
9.Don’t worry.This isn’t the_______(finally) result.
10.He is rich now,but he was_______(happy) in his childhood.
11.My brother is good at_______(make) jokes.
12.Ted is a(n)_______(honest) boy.He always tells lies.
13.It’s_______(wind) today.You’d better not go out.
14.They_______(main) talked about the weather the next day.
15.I_______(like) going out on rainy days.I prefer to stay at home.
Ⅴ.选词填空(5分) 从下面方框中选择合适的词语并用其适当形式填空。
Remind…of,get along with,escape from,worry,catch
1.Ann is very friendly.She is easy to_______.
2.Why do you look_______? What’s up?
3.A tiger________the zoo yesterday.
4.She________a very bad cold,so she didn’t go to school.
5.The song________me________my childhood.
Ⅵ.句型转换(10分) 根据括号内的要求改写下列句子,每空填一词。
1.I don’t like classical music at all.(改为同义句)
I don’t like classical music______ _____ _____.
2.I will take a small present.(改写为虚拟语气)
If I were you,I_______ ________a small present.
3.He is creative and outgoing.(对画线部分提问)
_______is he_______?
4.It must belong to Sonia,____ ____ ? (完成反意疑问句)
5.Lily likes this group.The group plays quiet and gentle music.(合并为一句)
Lily likes the group________ _______quiet and gentle music.
Ⅶ.汉译英(10分) 根据汉语句子,完成英语句子,每空限填一词。
1.如果这个表不走了怎么办?
______ ________this watch________work?
2.不要躺在床上看书,这对你的眼睛有害。
Don’t read in bed.It_______ ________ _______your eyes.
3.你不会使我失望,是吗?
You_____ _______ _______ _____ ,will you?
4.汤姆很快想出了那道题的答案。
Tom quickly_______ _________ ______the answer________the question.
5.他不可能在家,因为他去了北京。
He________ _______at home,because he has gone to Beijing.
6.她是唯一能在绳上行走的女孩。
She is the_______ _______ ________can walk on the string.
7.青少年应该远离网吧。
Teenagers______ _______ _____ ______ net bars.
8.尽管我忙,但我宁愿给他写信而不愿给他打电话。
I________writing to him________calling him though I’m busy.
9.他的新书上周出版了。
His new book________ _______last week.
10.李明是一个精力充沛的孩子,他从不感到疲劳。
Li Ming is________ _______boy and he________ _______tired.
Ⅷ.任务型阅读(10分) 阅读短文,根据要求完成各小题。
Many people go to school for an education.They learn languages,history,politics,geography,physics,chemistry and mathematics.Others go to school to learn a (2) skill so that they can make a living.School education is very important and useful.Yet,no one can learn everything from school.A teacher,no matter how much he knows,can not teach his students everything they want to know.The teacher’s job is to show his students how to learn.He teaches them how to read and how to think.So,much more is to be learned outside school by the students themselves (3).
It is always more important to know how to study by oneself than to memorize some facts or a formula(公式).It is actually quite easy to learn a certain fact in history or a formula in mathematics.But it is very difficult to use a formula in working out a math problem.Great scientists before us didn’t get everything from school.Some of them didn’t finish school.But they were all so successful.They invented so many things for us.The reason for their success is that they knew how to study.They read books that were not taught at school.(4)他们在读书的同时会问很多的问题。They did thousands of experiments.They worked hard all their lives and the most important thing is that they knew how to use their brain and how to study.
1.Can a student learn everything from school?
2.What’s the Chinese meaning of the word “skill” here?
3.将画线部分的句子翻译成汉语。
4.将画线部分的句子翻译成英语。
5.What can we learn from this text?
Ⅸ.短文填空(10分) 用括号中所给动词的适当形式填空,使短文意思完整、通顺。(共10空,每空1分,计10分)
注意:① 每个词只能用一次。② 有些词要根据需要使用相应的词形。③ 所给词中有两个是多余的。
Vegetable,way,is,do,forget,instead,eat,feel,make,well,because,swim
Do you want to __1__ healthier but don’t know why? It is very important to do exercise often and __2__ the right kind of food to stay healthy.
You don’t need to spend all day __3__ exercise to keep fit.Walking to school,cleaning the house or climbing stairs every day can be helpful.Unluckily,many teenagers __4__ these simple and easy __5__ to keep fit.
Different kinds of exercise such as running,__6__ and playing football make you __7__ good.They also help you to do __8__ at school than before.
Zhang Li,a doctor from a hospital in Beijing,says we should eat lower-fat food __9__ of fatty food like hamburgers,ice cream and popcorn.She says that __10__,fruits and whole grain(谷物) foods are good choices for everyday meals.
Ⅹ.书面表达(10分)
作为一名中学生,你学习的课程一定很多,但同时学校里又有丰富多彩的课外活动,例如:打球、集邮、电脑学习等。你最喜欢哪项活动?在那项活动中你做些什么?说说你的想法和理由。
要求:语句通顺,前后连贯;词数在80个词左右。
Key:
Ⅰ.1-5 BDCBC 6-10 DDADA
Ⅱ.1-5 DCABB 6-10 ACDBC
Ⅲ.1-5 DCBAB 6-10 BDCCA 11-15 CCBBA 16-20 DCABD
Ⅳ.1.permission 2.knowledgeable 3.author 4.creatures 5.sweet
6.increased 7.vegetarian 8.go 9.final 10.unhappy
11.making 12.dishonest 13.windy 14.mainly 15.dislike
Ⅴ.1.get along with 2.worried 3.escaped from 4.caught
5.reminded...of
Ⅵ.1.in the slightest 2.would take 3.What,like 4.isn’t it
5.that/who plays
Ⅶ.1.What if,doesn’t 2.is bad for 3.won’t let me down
4.came up with,to 5.can’t be 6.only girl who/that
7.should stay away from 8.prefer;to 9.came out
10.an energetic,never feels
Ⅷ.1.No,he/she can’t.
2.It means“技能/技术” in Chinese.
3.所以说更多的知识是学生在课外自学的。
4.They would ask many questions as they read.
5.It is always more important to know or learn how to study.
Ⅸ.1.be 2.eat 3.doing 4.forget 5.ways 6.swimming 7.feel
8.better 9.instead 10.vegetables