期刊文献+
共找到262篇文章
< 1 2 14 >
每页显示 20 50 100
H_(2)S在线监测装置研发及在锅炉水冷壁高温腐蚀防治中的应用
1
作者 熊小鹤 谭厚章 +4 位作者 邱选兵 李传亮 王承亮 杨祖旺 郭古青 《电力科技与环保》 2024年第2期125-132,共8页
锅炉水冷壁高温腐蚀问题一直是影响锅炉安全运行的难题。为解决锅炉水冷壁高温腐蚀的主要媒介H_(2)S需要连续测量,但当前行业内缺乏能长期运行的H_(2)S在线监测装置问题,研发了基于可调谐二极管吸收光谱TDLAS原理测量锅炉水冷壁H_(2)S... 锅炉水冷壁高温腐蚀问题一直是影响锅炉安全运行的难题。为解决锅炉水冷壁高温腐蚀的主要媒介H_(2)S需要连续测量,但当前行业内缺乏能长期运行的H_(2)S在线监测装置问题,研发了基于可调谐二极管吸收光谱TDLAS原理测量锅炉水冷壁H_(2)S的监测装置,并使用装置在某300 MW等级电站锅炉上进行了示范应用,跟踪评估了该装置的性能。结果显示,基于TDLAS原理所研发的仪器在现场投运12个月以来保持稳定运行,装置在线监测结果显示炉内H_(2)S呈现脉冲式波动特点,H_(2)S浓度高时超过1600μL/L。监测中发现,炉内H_(2)S浓度与运行调整存在较密切的关系,在升负荷过程中,由2台磨转为3台磨运行时,前后墙23.60 m平台测点处H_(2)S浓度急剧增加,从46μL/L增至822μL/L,H_(2)S与脱硫塔入口SO_(2)没有显著的关联性。H_(2)S在线监测装置的成功研发可以实现锅炉主燃烧器区域关键参数的在线监测,并作为运行人员调整锅炉运行参数的主要依据,这对于锅炉高温腐蚀监测和锅炉数字化建设具有积极意义。 展开更多
关键词 锅炉 水冷壁 高温腐蚀 H_(2)s 还原性气氛
下载PDF
不同下壁导联室性早搏R/S波比值的慢性心力衰竭患者近期预后随访分析
2
作者 陈航 曾久鑫 《西藏医药》 2024年第2期13-15,共3页
目的对不同下壁导联室性早搏R/S波比值的慢性心力衰竭患者近期预后随访进行分析。方法选择2020年3月~2022年3月本院收治的93例动态心电图检查存在室性早搏的CHF患者93例。所有患者完善24h动态心电图检查,随访一年。依照近期预后进行分组... 目的对不同下壁导联室性早搏R/S波比值的慢性心力衰竭患者近期预后随访进行分析。方法选择2020年3月~2022年3月本院收治的93例动态心电图检查存在室性早搏的CHF患者93例。所有患者完善24h动态心电图检查,随访一年。依照近期预后进行分组,将出现急性心肌梗死、恶性心律失常等不良心脏事件纳入预后不良组(n=37),其余未出现心脏不良事件的患者纳入预后良好组(n=56)。比较两组不同下壁导联室性早搏R/S波比值的预后。结果两组在年龄、BMI、吸烟、高血压、糖尿病、LVEF、利尿剂、地高辛方面差异无统计学意义(P>0.05);两组在性别、NYHA分级上差异有统计学意义(P<0.05);预后良好组R/S比值≥1例数比率高于预后不良组,R/S比值<1例数比例低于预后不良组,差异有统计学意义(P<0.05)。Logistic回归分析显示,R/S比值<1与性别、NYHA分级均是CHF患者近期预后不良的独立危险因素(P<0.05)。结论不同下壁导联的室性早搏R/S比值与其预后具有相关性,R/S比值<1是其不良预后的预测因素。 展开更多
关键词 慢性心力衰竭 下壁导联室性早搏 R/s波比值 预后
下载PDF
波纹管参数对TRB管胀形S型波纹管壁厚分布的影响
3
作者 何滔 顾栩 《机械设计与制造工程》 2023年第4期130-134,共5页
为研究TRB管无轴向补料胀形S型波纹管壁厚分布影响因素,通过理论设计构建了TRB管坯参数与S型波纹管参数的几何关系,并建立了胀形有限元模型。研究了S型波纹管参数波纹圆心角、波纹曲率半径、波纹管内半径对壁厚分布的影响。圆心角增大时... 为研究TRB管无轴向补料胀形S型波纹管壁厚分布影响因素,通过理论设计构建了TRB管坯参数与S型波纹管参数的几何关系,并建立了胀形有限元模型。研究了S型波纹管参数波纹圆心角、波纹曲率半径、波纹管内半径对壁厚分布的影响。圆心角增大时,设计壁厚与最大壁厚的差(正差)、与最小壁厚的差(负差)以及最大壁厚与最小壁厚的差(总差)快速增大,圆心角对壁厚分布影响显著。当圆心角为42°时,负差为设计壁厚的11.4%,总差为19.3%,壁厚分布不均匀。曲率半径和波纹管内半径对壁厚分布影响不显著,合理的参数范围内,TRB管胀形S型波纹管壁厚分布均匀。 展开更多
关键词 s型波纹管 TRB管 液压胀形 有限元 壁厚均匀
下载PDF
Khubchandani's procedure combined with stapled posterior rectal wall resection for rectocele 被引量:5
4
作者 Yi Shao Yong-Xing Fu +3 位作者 Qing-Fa Wang Zhi-Qiang Cheng Guang-Yong Zhang San-Yuan Hu 《World Journal of Gastroenterology》 SCIE CAS 2019年第11期1421-1431,共11页
BACKGROUND Obstructed defecation syndrome(ODS) is a widespread disease in the world.Rectocele is the most common cause of ODS in females. Multiple procedures have been performed to treat rectocele and no procedure has... BACKGROUND Obstructed defecation syndrome(ODS) is a widespread disease in the world.Rectocele is the most common cause of ODS in females. Multiple procedures have been performed to treat rectocele and no procedure has been accepted as the gold-standard procedure. Stapled transanal rectal resection(STARR) has been widely used. However, there are still some disadvantages in this procedure and its effectiveness in anterior wall repair is doubtful. Therefore, new procedures are expected to further improve the treatment of rectocele.AIM To evaluate the efficacy and safety of a novel rectocele repair combining Khubchandani's procedure with stapled posterior rectal wall resection.METHODS A cohort of 93 patients were recruited in our randomized clinical trial and were divided into two different groups in a randomized manner. Forty-two patients(group A) underwent Khubchandani's procedure with stapled posterior rectal wall resection and 51 patients(group B) underwent the STARR procedure.Follow-up was performed at 1, 3, 6, and 12 mo after the operation. Preoperative and postoperative ODS scores and depth of rectocele, postoperative complications, blood loss, and hospital stay of each patient were documented. All data were analyzed statistically to evaluate the efficiency and safety of our procedure.RESULTS In group A, 42 patients underwent Khubchandani's procedure with stapled posterior rectal wall resection and 34 were followed until the final analysis. In group B, 51 patients underwent the STARR procedure and 37 were followed until the final analysis. Mean operative duration was 41.47 ± 6.43 min(group A) vs39.24 ± 6.53 min(group B). Mean hospital stay was 3.15 ± 0.70 d(group A) vs 3.14± 0.54 d(group B). Mean blood loss was 10.91 ± 2.52 mL(group A) vs 10.14 ± 1.86 m L(group B). Mean ODS score in group A declined from 16.50 ± 2.06 before operation to 5.06 ± 1.07 one year after the operation, whereas in group B it was17.11 ± 2.57 before operation and 6.03 ± 2.63 one year after the operation. Mean depth of rectocele decreased from 4.32 ± 0.96 cm(group A) vs 4.18 ± 0.95 cm(group B) preoperatively to 1.19 ± 0.43 cm(group A) vs 1.54 ± 0.82 cm(group B)one year after operation. No other serious complications, such as rectovaginal fistula, perianal sepsis, or deaths, were recorded. After 12 mo of follow-up, 30 patients'(30/34, 88.2%) final outcomes were judged as effective and 4(4/34,11.8%) as moderate in group A, whereas in group B, 30(30/37, 81.1%) patients' outcomes were judged as effective, 5(5/37, 13.5%) as moderate, and 2(2/37,5.4%) as poor.CONCLUSION Khubchandani's procedure combined with stapled posterior rectal wall resection is an effective, feasible, and safe procedure with minor trauma to rectocele. 展开更多
关键词 RECTOCELE RECTAL prolapse Obstructed defecation syndrome Khubchandani’s PROCEDURE stapled POsTERIOR RECTAL wall REsECTION stapled transanal RECTAL REsECTION
下载PDF
Average temperature calculation for straight single-row-piped frozen soil wall 被引量:7
5
作者 XiangDong Hu SiYuan She RuiZhi Yu 《Research in Cold and Arid Regions》 2011年第2期124-131,共8页
The average temperature of frozen soil wall is an essential parameter in the process of design, construction, and safety manage- ment of artificial ground freezing engineering. It is the basis of calculating frozen s... The average temperature of frozen soil wall is an essential parameter in the process of design, construction, and safety manage- ment of artificial ground freezing engineering. It is the basis of calculating frozen soil's mechanical parameters, fiarther prediction of bearing capacity and, ultimately, safety evaluation of the frozen soil wall. Regarding the average temperature of sin- gle-row-piped frozen soil wall, this paper summarizes several current calculation methods and their shortcomings. Furthermore, on the basis of Bakholdin's analytical solution for the temperature field under straight single-row-piped freezing, two new calcula- tion models, namely, the equivalent trapezoid model and the equivalent triangle model, are proposed. These two approaches are used to calculate the average temperature of a certain cross section which indicates the condition of the whole frozen soil wall. Considering the possible parameter range according to the freezing pipe layout that might be applied in actual construction, this paper compares the average temperatures of frozen soil walls obtained by the equivalent trapezoid method and the equivalent tri- angle method with that obtained by numerical integration of Bakholdin's analytical solution. The results show that the discrepancies are extremely small and these two new approaches are better than currently prevailing methods. However, the equivalent triangle method boasts higher accuracy and a simpler formula compared with the equivalent trapezoid method. 展开更多
关键词 artificial ground freezing single-row-piped freezing frozen soil wall average temperature equivalent trapezoid method equivalent triangle method Bakholdin's solution
下载PDF
Semiconducting single-walled carbon nanotubes synthesized by S-doping 被引量:5
6
作者 Z.J.Li L.Wang +2 位作者 Y.J.Su P.Liu Y.F.Zhang 《Nano-Micro Letters》 SCIE EI CAS 2009年第1期9-13,共5页
An approach was presented for synthesis of semiconducting single-walled carbon nanotubes(SWNTs) by sulfur(S) doping with the method of graphite arc discharge. Raman spectroscopy, UV-vis-NIR absorption spectroscopy and... An approach was presented for synthesis of semiconducting single-walled carbon nanotubes(SWNTs) by sulfur(S) doping with the method of graphite arc discharge. Raman spectroscopy, UV-vis-NIR absorption spectroscopy and electronic properties measurements indicated the semconducting properties of the SWNTs samples. Simulant calculation indicated that S doping could induce convertion of metallic SWNTs into semiconducting ones. This strategy may pave a way for the direct synthesis of pure semiconducting SWNTs. 展开更多
关键词 s-doping sINGLE-wall Carbon nanotubes sEMICONDUCTING Arc discharge
下载PDF
Boundary-layer receptivity under interaction of free-stream turbulence and localized wall roughness 被引量:2
7
作者 Luyu SHEN Changgen LU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2016年第3期349-360,共12页
The boundary-layer receptivity under the interaction of free-stream turbu- lence (FST) and localized wall roughness is studied by the direct numerical simulation (DNS) and the fast Fourier transform. The results s... The boundary-layer receptivity under the interaction of free-stream turbu- lence (FST) and localized wall roughness is studied by the direct numerical simulation (DNS) and the fast Fourier transform. The results show that the Tollmien-Schlichting (T-S) wave packets superposed by a group of stability, neutral, and instability T-S waves are generated in the boundary layer. The propagation speeds of the T-S wave packets are calculated. The relation among the boundary-layer receptivity response, the amplitude of the FST, the roughness height, and the roughness width is determined. The results agree well with Dietz's experiments. The effect of the roughness geometries on the receptivity is also studied. 展开更多
关键词 boundary-layer receptivity Tollmien-schlichting (T-s wave free-streamturbulence (FsT) localized wall roughness
下载PDF
Wall's Beijing Corporation——A Large,Modern Sino-Foreign Ice Cream Joint Venture
8
作者 Wei Ming 《China's Foreign Trade》 1994年第12期20-21,共2页
Although it was reported that the title of 5000th Sino-foreign joint venture in Beijing had been conferred on Wall’s, it nevertheless remained a strange name to most Beijingers. However, on one of the hottest days la... Although it was reported that the title of 5000th Sino-foreign joint venture in Beijing had been conferred on Wall’s, it nevertheless remained a strange name to most Beijingers. However, on one of the hottest days last summer, the name Wall’s was seen in the Beijing streets and lanes, the ice-cream kept in small glass refrigerated cases standing under red and blue umbrellas with the trademark of Wall’s on them. This 展开更多
关键词 walls Beijing Corporation A Large Modern sino-Foreign Ice Cream Joint Venture
下载PDF
China Eastern's "2002 Wall Calendar of Success Immediately Upon Arrival"Obtained the National Patent
9
《China's Foreign Trade》 2002年第9期40-40,共1页
关键词 China Eastern’s wall Calendar of success Immediately Upon Arrival"Obtained the National Patent
下载PDF
Prognostic role of intestinal ultrasound in Crohn’s disease
10
作者 Cristina Manzotti Francesco Colombo +2 位作者 Tommaso Zurleni Piergiorgio Danelli Giovanni Maconi 《World Journal of Gastroenterology》 SCIE CAS 2023年第23期3595-3605,共11页
The majority of patients affected by Crohn’s disease(CD)develop a chronic condition with persistent inflammation and relapses that may cause progressive and irreversible damage to the bowel,resulting in stricturing o... The majority of patients affected by Crohn’s disease(CD)develop a chronic condition with persistent inflammation and relapses that may cause progressive and irreversible damage to the bowel,resulting in stricturing or penetrating complications in around 50%of patients during the natural history of the disease.Surgery is frequently needed to treat complicated disease when pharmacological therapy failes,with a high risk of repeated operations in time.Intestinal ultrasound(IUS),a non-invasive,cost-effective,radiation free and reproducible method for the diagnosis and follow-up of CD,in expert hands,allow a precise assessment of all the disease manifestations:Bowel characteristics,retrodilation,wrapping fat,fistulas and abscesses.Moreover,IUS is able to assess bowel wall thickness,bowel wall stratification(echo-pattern),vascularization and elasticity,as well as mesenteric hypertrophy,lymph-nodes and mesenteric blood flow.Its role in the disease evaluation and behaviour description is well assessed in literature,but less is known about the potential space of IUS as predictor of prognostic factors suggesting response to a medical treatment or postoperative recurrence.The availability of a low cost exam as IUS,able to recognize which patients are more likely to respond to a specific therapy and which patients are at high risk of surgery or complications,could be a very useful instrument in the hands of IBD physician.The aim of this review is to present current evidence about the prognostic role that IUS can show in predicting response to treatment,disease progression,risk of surgery and risk of post-surgical recurrence in CD. 展开更多
关键词 Intestinal ultrasound Crohn’s disease Postoperative recurrence Bowel wall thickness REMIssION Intestinal surgery
下载PDF
Writing’s on the Wall——爱在生死相逢时
11
作者 王勣 《新东方英语(中英文版)》 2016年第8期22-23,共2页
"Writing’s on the Wall"是"007"系列第24部电影《007:幽灵党》(Spectre)的主题曲,这首歌在2016年第88届奥斯卡颁奖典礼上摘得最佳原创歌曲大奖。2015年格莱美奖得主、英国歌手Sam Smith创作并献唱了这首歌。这是继英国最有成... "Writing’s on the Wall"是"007"系列第24部电影《007:幽灵党》(Spectre)的主题曲,这首歌在2016年第88届奥斯卡颁奖典礼上摘得最佳原创歌曲大奖。2015年格莱美奖得主、英国歌手Sam Smith创作并献唱了这首歌。这是继英国最有成就的男歌手之一Tom Jones录制1965年"007"电影的主题曲"Thunderball"之后, 展开更多
关键词 WRITING s on the wall 格莱美 奥斯卡颁奖 原创歌曲 爱情故事 伯沙撒 但以理 漫漫征程 WRITING
下载PDF
Deyang's Wall of Art
12
作者 FENG JING 《China Today》 1995年第5期21-24,共4页
Deyang'sWallofArt(Chinesemythologyisresurrectedtocreateamasterpieceinstone.)ByFENCJINGDEYANG,anindustrialcen... Deyang'sWallofArt(Chinesemythologyisresurrectedtocreateamasterpieceinstone.)ByFENCJINGDEYANG,anindustrialcenterinnorthernSich... 展开更多
关键词 Deyang’s wall of Art
下载PDF
重力式码头升级改造板桩墙后土压力分布
13
作者 彭志豪 陈海燕 《水运工程》 2024年第4期37-41,共5页
针对重力式码头升级改造新建板桩墙方案板桩墙后土压力分布问题,开展新建板桩墙距已有重力式墙身不同距离的土压力分布规律研究。采用有限元数值模拟和理论公式计算对比分析,得出作用在前板桩墙上的土压力小于理论主动土压力,即存在贮... 针对重力式码头升级改造新建板桩墙方案板桩墙后土压力分布问题,开展新建板桩墙距已有重力式墙身不同距离的土压力分布规律研究。采用有限元数值模拟和理论公式计算对比分析,得出作用在前板桩墙上的土压力小于理论主动土压力,即存在贮仓效应的结论。建议重力式码头改造工程设置前板桩墙时,采用公式合理选取贮仓尺寸,或根据新建板桩墙距已有码头墙身的距离采用有限元计算作用在板桩墙上的土压力,避免保守或激进设计。 展开更多
关键词 重力式码头 升级改造 新建板桩墙 贮仓压力 土压力分布
下载PDF
基于B/S模式的锅炉金属壁温在线监测系统 被引量:8
14
作者 高建强 陈聪 +3 位作者 李永华 陈鸿伟 王春波 廖丹 《中国电力》 CSCD 北大核心 2005年第12期68-71,共4页
在借鉴过程仿真和热力系统分析方法的基础上,开发了一套锅炉高温受热面金属壁温在线监测系统。该系统以一体化过程模型开发平台(IMMS)及其算法库为基础进行模型开发,利用火电厂已有的管理信息系统(MIS)采集机组运行数据,通过模型在线计... 在借鉴过程仿真和热力系统分析方法的基础上,开发了一套锅炉高温受热面金属壁温在线监测系统。该系统以一体化过程模型开发平台(IMMS)及其算法库为基础进行模型开发,利用火电厂已有的管理信息系统(MIS)采集机组运行数据,通过模型在线计算确定受热面管壁温度,并采用B/S结构显示实时监测信息。该系统已成功应用于某电厂200MW锅炉,有效减少了受热面超温爆管次数,延长了金属寿命,提高了机组安全经济运行水平。介绍系统的构成、功能及系统应用情况。 展开更多
关键词 锅炉 金属壁温 在线监测 B/s模式 模型开发平台
下载PDF
碳纳米管负载Mo-Co-S加氢脱氮催化剂研究 被引量:9
15
作者 董昆明 周金梅 +1 位作者 林国栋 张鸿斌 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2005年第2期217-223,共7页
用多壁碳纳米管(简写为CNTs)作载体制备负载型Mo Co S催化剂,x%MoiCoj/CNTs(x%为质量百分数),以乙腈和吡咯的加氢脱氮(HDN)作为探针反应,考察它们在该类催化剂上加氢脱氮的反应化学行为,并与γ Al2O3 和活性炭(AC)分别负载参比样作比较... 用多壁碳纳米管(简写为CNTs)作载体制备负载型Mo Co S催化剂,x%MoiCoj/CNTs(x%为质量百分数),以乙腈和吡咯的加氢脱氮(HDN)作为探针反应,考察它们在该类催化剂上加氢脱氮的反应化学行为,并与γ Al2O3 和活性炭(AC)分别负载参比样作比较研究.实验发现,在583 K,0.1 MPa,CH3CN/H2 =2.3/97.7(mol/mol),GHSV=2 200 mL(STP)·h-1·(g catal.)-1的反应条件下,在7.2%Mo3Co1/CNTs催化剂上,所观测乙腈 HDN的比反应速率达到 0.51μmol CH3CN·s-1·(mmol Mo)-1,是γ Al2O3 和AC分别负载相同Mo3Co1 载量催化剂的1.46和1.76倍,相应各自最佳Mo3Co1 载量催化剂的1.89和2.55倍.相似的反应化学行为在吡咯 HDN反应中也观测到.对比研究表明,用 CNTs代替γ Al2O3 或AC作为催化剂载体并不导致所负载Mo3Co1 催化剂上乙腈或吡咯HDN反应的表观活化能发生明显变化.H2 TPR研究揭示,与γ Al2O3 或AC负载的体系相比,CNTs负载催化剂具有较高的可还原性:不仅表现在其还原所需温度较低,还表现在较高的还原“比耗氢量”,后者暗示有较多的高价 Mon+ 物种可被还原至具催化活性的较低价态(Mo4+);在另一方面,CNTs载体对H2 优异的吸附活化性能可期在工作态催化剂表面营造较高氢稳态浓度的表面氛围; 展开更多
关键词 多壁碳纳米管 碳纳米管 负载Mo-Co-s催化剂 加氢精制技术 炼油工艺 载体
下载PDF
湍流模型对旋转状态下S型带肋回转通道内部换热特性的影响 被引量:5
16
作者 郑杰 朱惠人 +1 位作者 赵曙 梁卫颖 《科学技术与工程》 北大核心 2012年第9期2090-2095,共6页
应用数值模拟的方法研究了6种不同湍流模型,以及2种壁面函数对旋转状态下涡轮叶片S型带肋回转通道内部换热特性的影响,分析对比了S型带肋回转通道内部的流动规律,以及压力面和吸力面的换热情况。结果表明:在相同边界条件下不同湍流模型... 应用数值模拟的方法研究了6种不同湍流模型,以及2种壁面函数对旋转状态下涡轮叶片S型带肋回转通道内部换热特性的影响,分析对比了S型带肋回转通道内部的流动规律,以及压力面和吸力面的换热情况。结果表明:在相同边界条件下不同湍流模型的计算结果有很明显的差别,并且不同的壁面处理函数对计算结果也是有很大的影响;某些湍流模型的计算值只是在某个局部区域较为理想,在尚无普适性较好的湍流模型的情况下,研究在不同计算域和不同计算模型下采用不同湍流模型和壁面处理函数的计算技术,是一种较好的可行的方案。 展开更多
关键词 s型回转通道 湍流模型 换热 壁面函数
下载PDF
茜素红S/多壁碳纳米管修饰碳糊电极阳极溶出伏安法测定痕量铜 被引量:8
17
作者 邓培红 张军 黎拒难 《分析试验室》 CAS CSCD 北大核心 2009年第2期86-90,共5页
制备了茜素红S/多壁碳纳米管修饰碳糊电极,提出了一种灵敏的溶出伏安法测定痕量铜的新方法。在极谱分析仪上采用二阶导数线性扫描伏安法进行分析,在0.1moL/L的HAc-NaAc缓冲溶液(pH4.1)中,Cu与修饰电极表面的茜素红S(ARS)形成Cu(Ⅱ)-ARS... 制备了茜素红S/多壁碳纳米管修饰碳糊电极,提出了一种灵敏的溶出伏安法测定痕量铜的新方法。在极谱分析仪上采用二阶导数线性扫描伏安法进行分析,在0.1moL/L的HAc-NaAc缓冲溶液(pH4.1)中,Cu与修饰电极表面的茜素红S(ARS)形成Cu(Ⅱ)-ARS络合物而富集于电极表面,于-400mV处还原后,再进行阳极化扫描,于64mV处获得一灵敏的铜的阳极溶出峰,峰电流与Cu(Ⅱ)浓度在2×10-11mol/L~6×10-7mol/L范围内呈良好的线性关系,检出限(S/N=3)为8.0×10-12mol/L(富集时间240s)。方法应用于人发中铜含量的测定,回收率为98%~102%。 展开更多
关键词 多壁碳纳米管 茜素红s 化学修饰电极 阳极溶出伏安法
下载PDF
挤出过程中NR/SBR胶料壁滑移行为的研究──Ⅰ.压力波动现象 被引量:6
18
作者 梁基照 唐国俊 黄泽成 《华南理工大学学报(自然科学版)》 CSCD 1994年第1期120-126,共7页
应用Monsanto加工性能试验机(MPT)及一组直径和长径比不同的毛细管,考察了天然橡胶/丁苯橡胶(NR/SBR)胶料挤出流动中的壁滑移行为及其产生机理。试验发现,在一定的温度下,当表观剪切速率达到某一值时,总压力... 应用Monsanto加工性能试验机(MPT)及一组直径和长径比不同的毛细管,考察了天然橡胶/丁苯橡胶(NR/SBR)胶料挤出流动中的壁滑移行为及其产生机理。试验发现,在一定的温度下,当表观剪切速率达到某一值时,总压力降急剧下降。而临界的表观剪切速率则随着口型直径的增加而减小;壁滑移发生在口型出口附近.这种压力波动现象主要归因于试样的壁滑移行为。 展开更多
关键词 挤出 壁滑移 天然橡胶 丁苯橡胶
下载PDF
深海S-lay铺设大直径薄壁管道的奇异摄动分析 被引量:3
19
作者 韩强 汪志钢 +1 位作者 张永强 陶旭 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2015年第6期116-121,共6页
文中利用奇异摄动理论得到了深海管道S-lay铺设过程中的构型解析解,并研究了不同张紧力、水深以及海流力对管道构型及弯矩的影响.同时,采用有限元法对深海大直径管道铺设过程进行了数值仿真,并与奇异摄动解进行了对比和验证.理论结果表... 文中利用奇异摄动理论得到了深海管道S-lay铺设过程中的构型解析解,并研究了不同张紧力、水深以及海流力对管道构型及弯矩的影响.同时,采用有限元法对深海大直径管道铺设过程进行了数值仿真,并与奇异摄动解进行了对比和验证.理论结果表明:其他参数相同时,适当增大张紧力可使管道构型更平缓,对铺管有利;海水越深,管道的构型越陡,靠近海底处管道的弯矩峰值越大,对铺管不利;当管道受到与铺设方向相反的海流力时,海流力越大,靠近海底部管道弯矩的峰值越大,对铺管越不利. 展开更多
关键词 s-lay 薄壁管道 奇异摄动 解析解 有限元法
下载PDF
基于TDLAS的煤粉锅炉水冷壁近壁面CO/H_(2)S同步在线监测 被引量:8
20
作者 彭志敏 贺拴玲 +5 位作者 周佩丽 杜艳君 王振 丁艳军 吴玉新 吕俊复 《热力发电》 CAS CSCD 北大核心 2022年第10期145-152,共8页
煤粉锅炉低氮燃烧工况下还原性气氛H_(2)S和CO体积分数上升导致水冷壁高温腐蚀严重,实时在线监测水冷壁近壁面CO/H_(2)S体积分数并基于测得的数据建立高温腐蚀预警模型具有重要意义。采用可调谐二极管激光吸收光谱(TDLAS)技术测量锅炉... 煤粉锅炉低氮燃烧工况下还原性气氛H_(2)S和CO体积分数上升导致水冷壁高温腐蚀严重,实时在线监测水冷壁近壁面CO/H_(2)S体积分数并基于测得的数据建立高温腐蚀预警模型具有重要意义。采用可调谐二极管激光吸收光谱(TDLAS)技术测量锅炉水冷壁近壁面CO/H_(2)S体积分数,首先利用赫里奥特多次反射池提高测量精度并降低检测限,然后开展CO/H_(2)S体积分数动态测量验证实验。结果表明,CO、H_(2)S分别在0~2000μL/L和0~20μL/L范围内,测量值与配比值一致且具有较高的精度。最后结合恒流稀释烟气高保真预处理技术将研制的CO/H_(2)S监测装置应用于大型火电机组煤粉锅炉现场,采用轮测方式实现了锅炉炉膛“还原区”和“燃尽区”CO/H_(2)S同步在线监测;同时基于监测数据反馈对锅炉燃烧进行调整,在确保烟气超低排放基础上减缓水冷壁高温腐蚀速率,实现火电机组高效、环保、安全和智能化运行。 展开更多
关键词 可调谐二极管激光吸收光谱 煤粉锅炉 水冷壁高温腐蚀 CO/H_(2)s在线监测
下载PDF
上一页 1 2 14 下一页 到第
使用帮助 返回顶部