浅析电力拖动自动控制系统

电力拖动控制系统是一种较为重要的控制系统，其在工业生产中发挥着很大的作用，随着社会的发展以及科技的推动，这一系统开始趋向于自动化的应用形式。电能在人们的生活中发挥着重要的作用，电器的种类越来越多，现代社会对电力的需求量也越来越大，所以，自动化的电力拖动控制系统，可以更好的满足人类社会对电力的需求。本文分析了电力拖动自动控制系统的设计原理，还介绍了电力拖动自动控制系统的安全防护，希望对相关电力人员有所帮助，使相关企业生产可以更加安全、稳定的进行。     

浅析电力拖动自动控制系统

电力拖动控制系统是一种较为重要的控制系统,其在工业生产中发挥着很大的作用,随着社会的发展以及科技的推动,这一系统开始趋向于自动化的应用形式。电能在人们的生活中发挥着重要的作用,电器的种类越来越多,现代社会对电力的需求量也越来越大,所以,自动化的电力拖动控制系统,可以更好的满足人类社会对电力的需求。本文分析了电力拖动自动控制系统的设计原理,还介绍了电力拖动自动控制系统的安全防护,希望对相关电力人员有所帮助,使相关企业生产可以更加安全、稳定的进行。     

带式输送机变频驱动装置的研究

介绍了带式输送机对驱动装置的要求,依据要求结合一部三台电机驱动双滚筒的带式输送机对驱动装置进行设计。驱动装置采用PLC为主控制器,变频器驱动三相异步电动机。分别对变频驱动装置的启动控制和三台电机之间的功率平衡控制进行了分析和设计。     

探讨利用功率曲线分析抽油机的平衡率

抽油机如果在平衡较好的状态下运转,不但可以减少抽油机减速箱的最大输出扭矩,延长设备的使用周期,而且还可以减少设备对电网的最大需量,并且节省电力以及相关耗材费用的支出。较好的抽油机平衡应该是上行所做功和下行所做功趋于一致,平衡差的抽油机两者的做功差别较大,平衡很差的会在一段时间消耗很多的电力,而另一段时间还要向电网回馈电力,其回馈的电力还会对电网及用电设备造成损害。而目前抽油机平衡率测试方法为上下行电流峰值对比法,但电流并不真正代表拖动电机做功量,因此本文提出了功率法测试评价抽油机平衡率。     

提高电机拖动类课程教学质量的方法探讨

《电机拖动基础》、《电力拖动自动控制系统》是自动化专业的主干课程,其内容抽象、知识点多、综合性强,学生在学习过程中难以理解。本文从教师自身素质和业务水平、课堂教学水平、实践教学、考核方式四个方面探讨了该类课程教学质量的提高方法。     

多台高压变频器同步控制技术在乌海公务素煤矿三号主井皮带上的应用

本文主要介绍了乌海公务素主井皮带系统的构成、工作原理和三台高压变频器在皮带上的控制,同时介绍了多台高压变频器同步控制技术在皮带现场的应用,阐述变频控制在皮带控制系统的优越性。     

基于IR2113的直流电机调速系统

本文介绍了一种以IR2113芯片为驱动核心芯片的新型小功率直流调速控制系统的设计方案,介绍了系统的硬件实现以及软件关键部分的解析。经实验证明:所设计的直流电机控制器性能可靠、成本低廉,是一款优越的新型小功率直流电机调速系统。     

红沿河核电站调试启动期间的计划管理体系

<正>核电机组调试启动是将已安装好的系统设备逐步投入运行以验证性能,在反应堆临界后试验性的提升功率,最终考核机组整体运行水平是否达到设计要求,是否满足性能标准的过程。一台机组调试启动历经单系统试验、核冲洗和开盖冷试、冷试、热试准备、热试、装料准备、堆芯装料、临界前试验、首次临界和低功率试验、功率提升试验共10个阶段,涉及1700多个调试试验,其中间又安排了安装尾项、接产联检、遗留项清理、生产定期试验、运行程序生效、     

功率电传作动技术的研究进展

功率电传作动是指飞机次级能源系统至作动系统之间的功率传输是通过导线以电能量传输的方式完成的,是发展多电飞机的关键技术之一。目前功率电传作动器发展出机电作动器和电静液作动器两种主要形式。从多电飞机的应用出发,对功率电传作动器进行了概述,重点介绍了机电作动器技术,以及应用特点,并讨论了机电作动器的关键技术。     

浅谈全厂DCS一体化方案在联合循环机组的应用

以珠海横琴岛多联供燃气能源站项目为背景,介绍了全厂采用DCS进行一体化监控的设计方案。每台机组设置一套DCS,两台机组设置一套DCS公用网,四机公用系统设置一套辅助车间控制网DCS。目前一期两台机组已全面建成投产,监控运行状态良好,证实了全厂DCS一体化网络结构在燃气蒸汽联合循环机组中的可推广性。     

商会自治的基石——商会自治规范研究

在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。     

癸氧喹酯干混悬剂含量测定的改进

采用高效液相色谱法测定癸氧喹酯干混悬剂的含量,在2-250μg/mL范围内,峰面积的常用对数与进样量浓度的常用对数呈良好的线性关系,R^2=1(n=5),平均回收率为99.24%~99.51%,RSD在0.05%~0.28%。此方法分析时间短,样品前处理简便、定量结果准确,重现性好,结果满意,为其质量控制提供了依据。     

猪毛色遗传的研究进展

本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。     

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air.     

不同样本商品蜂蜜中硒含量的测定

用硝酸和高氯酸消化蜂蜜,使硒游离出来,在微酸性环境下,硒和2,3-二氨基萘(DAN)生成有较强荧光的物质,用环己烷萃取,在激发波长378nm,荧光波长518nm处测定其荧光强度。蜂蜜中硒含量范围:0.10～0.82μg/g。表明:蜂蜜应视为天然富硒营养品。     

乳酸杆菌益生作用机制的研究进展

乳酸杆菌作为益生菌广泛用于人和动物。本文综述了乳酸杆菌改善宿主健康的机制。乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道。文章重点讨论了乳酸杆菌表面成分（表面蛋白、脂磷壁酸和肽聚糖）与肠道受体（Ｃ型凝集素受体、Ｔｏｌｌ样受体和 Ｎｏｄ样受体）,阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制。     

Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF

Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo.     

Mechanism of Action of Probiotic Function of Lactobacilli

乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制.     

中华人民共和国农业部公告 第267号

为贯彻落实《兽药生产质量管理规范》(简称《兽药GMP》),进一步推动兽药GMP实施进程,我部制定了《兽药生产质量管理规范检查验收办法》,现予公告。本公告自2003年6月1日起施行。附件:兽药生产质量管理规范检查验收办法二○○三年四月十日第一章 总则 第一条 为推动《兽药生产质量管理规范》(以下简称兽药GMP)的实施,规范兽药GMP检查验收工作,制定本办法。 第二条 农业部负责全国兽药GMP管理和检查验收工作;负责制修订兽药GMP检查验收管理规定;负责兽药GMP检查员队伍建设和监督管理工作,负责国际兽药贸易中GMP互认工作。 …