基于GB151方法验算立式蒸汽发生器管板厚度

在压水堆核电厂立式蒸汽发生器设计中,强度计算是确定各部分基本尺寸的重要依据。其中,管板作为一二次侧的压力边界,同时本身有数量众多的开孔,厚度取值尤为重要。本文在压水堆核电厂蒸汽发生器设计中常用的管板计算方法基础上,采用国家标准GB151《管壳式换热器》进行验算。结果表明,国家标准GB151的验算精度良好,可以作为管板强度计算常用方法的有效补充。     

浅谈无损检测技术在AP1000蒸汽发生器管板加工中的应用

本文介绍了目前国内外常用的几种无损检测技术,结合AP1000蒸汽发生器管板加工,对无损检测技术中的渗透检测(PT)在AP1000蒸汽发生器管板加工中的应用进行了探讨,着重地从液体渗透检验试剂、检验程序以及检验标准等方面进行了探究。     

WWER1000堆型卧式蒸汽发生器解体检修辐射防护实践

田湾核电站1、2号机组蒸汽发生器为WWER1000堆型卧式蒸汽发生器,它由容器、传热面、一回路冷却剂集流管、主给水分配装置、应急给水分配装置、蒸汽分离孔板和水下均汽板等部件组成。文章重点对WWER1000堆型蒸汽发生器解体检修的辐射防护实践进行介绍,对田湾核电站历次大修现场辐射水平及集体剂量情况进行分析,并提出后续的优化方向。     

液压胀接压力理论计算研究

本文结合蒸汽发生器管子管板胀接机构及材料特性,采用用简化的两端开口的套筒模型,对该产品液压胀接压力进行了计算和确定,为后续实施胀接工艺评定、产品胀接提供了理论基础和数据。     

对凝汽器钛管泄漏的认识

凝汽器作为二回路的一个重要设备,它对汽轮机的正常经济运行起着至关重要的作用。秦山二期的凝汽器有5800根钛管,在长期的运行中一旦其中某些钛管破损,就有可能使海水泄露入凝汽器,随之带入SG(蒸汽发生器)二次侧,使二次侧水质变差,钠、氯离子浓度高会导致蒸汽发生器传热管腐蚀,引起蒸汽发生器破管,后果十分严重。所以,控制好凝汽器钛管的运行,对机组的稳定运行和电厂经济效益显得非常重要。     

压水堆核电站蒸汽发生器水位控制

压水堆核电站配置有一套完善的蒸汽发生器水位测量装置,用于全范围的蒸汽发生器的水位控制。本文通过对蒸汽发生器水位控制原理的展述,展开蒸汽发生器水位控制方法,共同提高控制蒸汽发生器水位的技能。     

太阳能制冷器冷凝器研究与开发

本文介绍了一种新型的管壳式冷凝器,它是太阳能吸收式制冷机的重要换热设备之一,其主要作用是将发生器排出的过热制冷剂蒸汽冷凝成为饱和液体,经U形管节流后进入蒸发器吸热蒸发,达到制冷目的.与传统的冷凝器相比,它采用了外螺纹强化换热管,具有换热系数大、体积小、不易结垢等优点.并加装了折流板,增加了气体与管壁的接触时间,从而增强了换热效果.本文介绍了冷凝器的原理、结构、功能,并进行了设计计算和校核.最后,利用Solid works的三维造型功能来设计冷凝器的模型.     

蒸汽发生器汽水分离器改进设计数值分析

对核电蒸汽发生器的汽水分离器进行改进设计后进行数值分析计算,从汽水分离器的阻力和分离效率两两方面对计算结果进行分析。结果表明,缩比后的汽水分离器满足蒸汽发生器的使用要求。本文的目的是通过数值分析获得汽水分离器主要结构参数的变化对分离器性能的影响趋势,为试验研究的模拟件设计提供依据。     

浅析核电厂蒸汽发生器传热管降质及堵管技术

本文分析了蒸汽发生器传热管降质的原因,传热管降质的机理,以及易出现降质的部位,提出预防手段;简要介绍规范要求的及非规范要求的蒸汽发生器在役检查主要内容,以及破损传热管的三种堵管方式;以远程机械拉拔式堵管技术为例简单阐述国内堵管技术的现状。结合国内外最新的蒸汽发生器堵管技术对堵管技术的发展方向进行探讨。     

PRS系统蒸汽管道隔离阀冷凝计算分析

蒸汽发生器二次侧非能动冷却系统(PRS)用以应对全厂断电叠加辅助给水系统失效的工况。PRS系统利用高处的冷凝水箱将蒸汽发生器的余热带出,最终通过冷凝水箱中水的蒸发将热量带入大气中。在机组正常运行期间,PRS系统蒸汽管线隔离阀前为高温高压水蒸气,阀后为低温低压的空气。若将PRS蒸汽管线隔离法机组运行期间,蒸汽在蒸汽管道隔离阀阀瓣处冷凝成水,如果这部分水回流到主蒸汽管道中,则会增大汽轮机入口的蒸汽湿度。本文计算分析了PRS系统蒸汽管道产生的凝结水,并评价了其对蒸汽发生器含湿量的影响。     

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。     

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。 …     

鸡败血支原体垂直传播模式及其阻断方法

以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。     

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.