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Effects of Tube Depth and Infusion Rate of Continuous Humidification by Endotracheal Intubation on Humidification Effect
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作者 Hui Sun Dan Li +1 位作者 Wan Luo Lin Feng 《Open Journal of Nursing》 2017年第1期123-127,共5页
Objective: To investigate the continuous humidification tube insertion depth of endotracheal intubation and the flow rate of the wetting effect. Methods: From October 2008 to May 2010, among 132 patients of oral and m... Objective: To investigate the continuous humidification tube insertion depth of endotracheal intubation and the flow rate of the wetting effect. Methods: From October 2008 to May 2010, among 132 patients of oral and maxillofacial surgery with tracheal intubation, continuous infusion can be adjusted to the wet method;according to the wet pipe, insertion depth of the flow rate is divided into four groups, by four different depths and velocities of the wetting effect, to be analyzed. Results: B group was significantly lower than other groups satisfied with indicators of four significantly different effects of humidification. Conclusion: When continuous humidification tube insertion depth of endotracheal intubation is 10 - 12 cm, and flow rate is 15 - 20 ml/h, the wetting effect will achieve greater satisfaction. 展开更多
关键词 INTUBATION Continuous HUMIDIFICATION tube depth INFUSION Rate HUMIDIFICATION EFFECT
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Weak correlation of flower color and nectar-tube depth in temperate grasslands 被引量:1
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作者 Julia Binkenstein Martina Stang +1 位作者 Julien P.Renoult H.Martin Schaefer 《Journal of Plant Ecology》 SCIE CSCD 2017年第2期397-405,共9页
Aims Nectar is one of the most common floral rewards offered to pol-linators by plants.Depending on the plant species,nectar is offered openly or in tubes of various lengths restricting accessibility of this resource ... Aims Nectar is one of the most common floral rewards offered to pol-linators by plants.Depending on the plant species,nectar is offered openly or in tubes of various lengths restricting accessibility of this resource for flower visitors with short mouthparts.if attract-ing pollinators that match floral morphology increases pollination efficiency,flowers could profit from signaling nectar-tube depth to pollinators.Since flower colors are important signals in plant-pol-linator communication,we investigated whether and which differ-ent chromatic or achromatic aspects of flower color might indicate nectar-tube depth or whether flower colors facilitate the differen-tiation between flowers with long nectar tubes by means of high chromatic uniqueness.Methods To this end,we collected flower reflectance spectra of 135 grassland plant species.We analyzed flower colors as raw reflectance spectra in principal component analysis(PCA)and in the color space of honeybees.Important Findings The correlation between flower colors and tube depths was weak.From the bee’s point of view,blue flowers had on average deeper tubes than green,blue-green and UV-green flowers potentially allow-ing insects to predict tube depths based on blue color.Spectral purity did not correlate with nectar-tube depth,nor did the chromatic uniqueness of flower colors in the honeybee color space.Dominant wavelength showed a significant but very weak correlation with tube depth.The achromatic green contrast decreased with increasing tube depth as did brightness;thus deep tubes were less conspicuous than shallow tubes.Chromatic components resulting from PCA did not or only slightly correlate with tube depth.Our results illustrate that flower colors may have a certain potential to indicate tube depth,i.e.nectar accessibility,from a bee’s perspective. 展开更多
关键词 VISION pollination efficiency plant-animal interaction NECTAR tube depth
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The Influence of Notch Depth on the Response of Local Sharp-Notched Circular Tubes under Cyclic Bending
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作者 Kuo-Long Lee Ching-Hsun Meng Wen-Fung Pan 《Journal of Applied Mathematics and Physics》 2014年第6期335-341,共7页
In this paper, the mechanical behavior and buckling failure of SUS304 stainless steel tubes with different local sharp-notched depths subjected to cyclic bending were experimentally investigated. It can be seen that t... In this paper, the mechanical behavior and buckling failure of SUS304 stainless steel tubes with different local sharp-notched depths subjected to cyclic bending were experimentally investigated. It can be seen that the experimental moment-curvature relationship exhibits cyclic hardening and becomes a steady loop after a few cycles. However, the experimental ovalization-curvature relationship exhibits an increasing and ratcheting manner with the number of the bending cycles. In addition, higher notch depth of a tube leads to a more severe unsymmetrical trend of the ovalization-curvature relationship. It has been observed that the notch depth has almost no influence on the moment-curvature relationship. But, it has a strong influence on the ovalization-curvature relationship. Finally, the theoretical model proposed by Kyriakides and Shaw [1] was used in this study for simulating the controlled curvature-number of cycles to produce buckling relationship. Through comparison with the experimental data, the theoretical model can properly simulate the experimental 展开更多
关键词 Circular tube LOCAL SHARP NOTCH NOTCH depth CYCLIC BENDING
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Novel Formula for Calculation of the Optimal Insertion Depth for Cuffed Endotracheal Tubes in Pediatric Major Surgery
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作者 Mao Kinoshita Kazuma Hayase +3 位作者 Mizuki Bando Naofumi Kawai Masaru Shimizu Masayuki Shibasaki 《Open Journal of Anesthesiology》 2019年第3期42-50,共9页
Background: Accurate determination of the optimal insertion depth of a pediatric endotracheal tube (ETT) is quite important. The aim of this study was to create an easily available formula that can be used to determin... Background: Accurate determination of the optimal insertion depth of a pediatric endotracheal tube (ETT) is quite important. The aim of this study was to create an easily available formula that can be used to determine the optimal insertion depth for a cuffed ETT even without depth marking with clear definitions of the upper and lower limits for the tip of ETT in the trachea in clinical practice. Methods: Eighty children under 12 years of age were enrolled. The depth marking of the cuffed ETT was placed at the vocal cords and both lungs were then auscultated using a stethoscope. The upper limit was radiographically defined as the position of the tip of the cuffed ETT being between the clavicles. The lower limit was defined as a distance of 5 mm above the carina. The relationship between the insertion depth and patient characteristics was analyzed to create a formula for optimal ETT insertion depth. Results: Sixty-nine ETTs were optimally placed in the trachea. There were good correlations between the optimal insertion depth of ETTs and patients characteristics (height (R = 0.92);BSA (R = 0.92);weight (R = 0.91);age (R = 0.88)). Using these patient characteristics, we created the following three formulas for calculation of the optimal insertion depth for pediatric cuffed ETTs: insertion depth (cm) = height (cm)/11 + 5.5, weight (kg)/3 + 9.5 or 11 + 3/4 × age (years). The rates of appropriate tube placement of both pediatric cuffed ETTs were 87.5% (Hi-Contour) and 85.0% (Microcuff). Conclusions: Our formula and graphs may be easy to determine the optimal insertion depth of cuffed ETT even without depth marking in clinical practice. 展开更多
关键词 INSERTION depth INFANTS Small Children Cuffed ENDOTRACHEAL tubeS
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Comparison of the Effectiveness of Marked Suction Tubes vs. Plain Suction Tubes in Pediatric Mechanically Ventilated Patients
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作者 Kexin Yang Yang Zhang +5 位作者 Menghui Duan Qiuju Liang Jianfei Zhang Ping Kong Mengqi Duan Xiangwei Chen 《Open Journal of Pediatrics》 2023年第6期774-784,共11页
Introduction: Endotracheal suction plays a crucial role in the management of mechanically ventilated patients. This study aims to evaluate the clinical effectiveness and safety of suction tubes with markings in mechan... Introduction: Endotracheal suction plays a crucial role in the management of mechanically ventilated patients. This study aims to evaluate the clinical effectiveness and safety of suction tubes with markings in mechanically ventilated pediatric patients. Materials and Methods: A randomized assignment was carried out on a cohort of 52 pediatric patients who underwent mechanical ventilation in the Pediatric Intensive Care Unit at the Third Affiliated Hospital of Sun Yat-sen University, covering the period from January 2022 to December 2022. These patients were divided into two groups: an improved group (n = 26) utilizing marked suction tubes, and a regular group (n = 26) employing conventional suction tubes. The objective of our study was to evaluate the clinical effectiveness of marked suction tubes. Results: The effects of the improved group on the vital signs of children undergoing mechanical ventilation were small and statistically significant compared with the regular group (p < 0.05). Additionally, the improved group exhibited a reduced frequency of sputum suction, shorter mechanical ventilation duration, and fewer days of hospitalization in the PICU compared to the regular group during the ventilation period. Notably, the difference in the duration of PICU hospitalization was statistically significant (p < 0.05). Moreover, the incidence of adverse reactions in the improved group was notably lower, with statistically significant differences observed in airway mucous membrane damage and irritating cough when compared to the regular group (p < 0.05). Conclusion: The utilization of marked suction tubes provides clinical nurses with clear guidance for performing suctioning with ease, efficiency and safety. Consequently, advocating for the widespread implementation of marked suction tubes in clinical practice is a commendable pursuit. 展开更多
关键词 Marked Suction tubes Endotracheal Suction Mechanical Ventilation Different depth of Aspiration
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盐湖大气环境下316 L仪表管点蚀深度预测研究
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作者 骆正山 刘月 《中国安全生产科学技术》 CAS CSCD 北大核心 2024年第6期105-110,共6页
为提高316 L仪表管在盐湖大气环境下点蚀深度的预测精度,采用变阶平均弱化缓冲算子、积分背景值和新陈代谢对分数阶累加灰色模型FGM(1,1,r)进行改进,首先通过改进Tent混沌映射、莱维飞行和区间自适应反向学习策略提高黏菌算法(SMA)的寻... 为提高316 L仪表管在盐湖大气环境下点蚀深度的预测精度,采用变阶平均弱化缓冲算子、积分背景值和新陈代谢对分数阶累加灰色模型FGM(1,1,r)进行改进,首先通过改进Tent混沌映射、莱维飞行和区间自适应反向学习策略提高黏菌算法(SMA)的寻优能力和收敛速度,随后利用改进黏菌算法(ISMA)对FGM(1,1,r,ρ)中的参数r和ρ进行寻优,最后构建仪表管ISMA-FGM(1,1,r,ρ)点蚀深度预测模型。研究结果表明:经优化的新模型比原模型误差更小、拟合度更高,在仪表管点蚀深度预测方面具有更好的性能。研究结果可为仪表管道系统的完整性评价和风险预警提供参考。 展开更多
关键词 盐湖大气环境 316 L仪表管 点蚀深度 改进黏菌算法(ISMA) FGM(1 1 r)模型
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延长鼻胃管置入深度在重症患者肠内营养治疗中的应用价值
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作者 陈金连 罗春霞 +1 位作者 曾丽云 田木华 《蛇志》 2024年第2期147-150,共4页
目的观察延长鼻胃管置入深度在重症患者肠内营养支持治疗中的应用价值。方法选择2023年4~9月在三明市第二医院重症医学科经鼻胃管肠内营养治疗的100例患者,按随机数字表法分为对照组和观察组,每组50例。两组均给予肠内营养治疗。对照组... 目的观察延长鼻胃管置入深度在重症患者肠内营养支持治疗中的应用价值。方法选择2023年4~9月在三明市第二医院重症医学科经鼻胃管肠内营养治疗的100例患者,按随机数字表法分为对照组和观察组,每组50例。两组均给予肠内营养治疗。对照组鼻胃管置入深度为45~55 cm,观察组鼻胃管置入深度为60~65 cm。比较两组干预前及干预7 d后的胃潴留、胃食管反流、呕吐、显性误吸等并发症的发生率及血红蛋白(Hb)、血清白蛋白(Alb)、前白蛋白(PAB)水平改善情况。结果观察组的胃潴留、胃食管反流、呕吐、显性误吸发生率均低于对照组,差异均有统计学意义(均P<0.05)。观察组的Hb、Alb、PAB水平均显著高于对照组,差异均有统计学意义(均P<0.05)。结论延长鼻胃管置入深度可以减少患者肠内营养并发症的发生,有效改善患者营养状况。 展开更多
关键词 延长置入深度 鼻胃管 肠内营养 重症医学 营养改善效果
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小角度缠绕复合材料护岸管桩抗弯性能试验与设计
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作者 张恒 方海 +2 位作者 王肖淳 夏国龙 徐双 《复合材料科学与工程》 CAS 北大核心 2024年第4期90-96,共7页
本文提出一种新型复合材料护岸管桩。该护岸管桩由纤维缠绕工艺制备的复合材料缠绕管制成。通过四点弯曲试验,得到试件的破坏模式以及荷载-位移关系,以此分析缠绕角度±55°、±15°以及是否浇筑混凝土对护岸管桩抗弯... 本文提出一种新型复合材料护岸管桩。该护岸管桩由纤维缠绕工艺制备的复合材料缠绕管制成。通过四点弯曲试验,得到试件的破坏模式以及荷载-位移关系,以此分析缠绕角度±55°、±15°以及是否浇筑混凝土对护岸管桩抗弯性能影响。结果表明:纤维缠绕角度由55°减小为15°与浇筑混凝土都能极大提高复合材料护岸管桩的刚度和抗弯承载力。在此基础上进行复合材料护岸管桩嵌固端深度计算公式推导,并给出护岸管桩的设计流程以及应用建议。这为之后复合材料护岸管桩应用于护岸工程提供了参考。 展开更多
关键词 护岸管桩 复合材料缠绕管 四点弯曲试验 嵌固端深度 设计流程
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深圳岗厦北综合交通枢纽大尺寸钢管混凝土半埋 入式柱脚性能试验研究
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作者 张素梅 罗贤志 +5 位作者 李爱东 张晨明 王玉银 郭兰慧 宋帛洋 张磊 《建筑结构》 北大核心 2024年第8期1-10,90,共11页
深圳岗厦北综合交通枢纽位于地下空间资源紧张的城市核心区,规模巨大且荷载工况复杂,核心换乘区设有51.2m×48.0m的无柱超大跨中庭。为解决由场地条件限制导致的柱脚埋深不足问题,结合已有研究成果和工程实践经验,依托深圳岗厦北综... 深圳岗厦北综合交通枢纽位于地下空间资源紧张的城市核心区,规模巨大且荷载工况复杂,核心换乘区设有51.2m×48.0m的无柱超大跨中庭。为解决由场地条件限制导致的柱脚埋深不足问题,结合已有研究成果和工程实践经验,依托深圳岗厦北综合交通枢纽,提出并设计了半埋入式钢管混凝土柱脚节点。为检验节点可靠性,通过1/5大比例缩尺模型试验结合数值分析研究了轴力、剪力和弯矩共同作用下的半埋入式柱脚节点的力学响应,分析了柱脚内部的应力分布规律,揭示了同时设置环板和栓钉作为抗剪连接件时的工作机理。分析结果表明:设计荷载工况下,钢管混凝土柱轴力主要通过环板和柱脚底板传递,弯矩主要通过钢管侧壁承压传递;环板埋深较浅时可以获得较高的传力效率,但其下部混凝土易出现应力集中;钢管侧壁栓钉在埋置深度范围内均能够较好地发挥抗剪作用。承台下部桩基布置合理,设计荷载工况下未见承台冲切破坏特征、节点整体处于弹性工作状态;1.2倍设计荷载工况下节点刚度仍未见明显退化,节点混凝土未出现压溃或剥落,表面无可见裂缝发展,各关键位置钢材应力低于材料强度。设置环板和栓钉作为剪力连接件的半埋入式柱脚可以实现对钢管混凝土柱的可靠嵌固,提出的采用抗剪环板加强的钢管混凝土半埋入式柱脚节点设计与构造方案合理可行,满足结构安全要求。 展开更多
关键词 钢管混凝土 半埋入式柱脚 柱脚埋深 环板 模型试验 数值分析 受力性能
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千米采深矿区锚杆拉拔试验研究
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作者 王玺 吴钦正 +2 位作者 李施庆 王小奇 郑永升 《矿业工程》 CAS 2024年第3期8-10,16,共4页
针对千米采深矿区缺乏锚杆支护效果评测的现状,利用自主研发的锚杆智能拉拔测试系统,选取深部两个分段管缝锚杆进行了拉拔测试,获得不同长度、不同位置锚杆的拉拔力变化规律,并给出了相应的支护建议。研究表明:1.3 m锚杆锚固力在25 kN左... 针对千米采深矿区缺乏锚杆支护效果评测的现状,利用自主研发的锚杆智能拉拔测试系统,选取深部两个分段管缝锚杆进行了拉拔测试,获得不同长度、不同位置锚杆的拉拔力变化规律,并给出了相应的支护建议。研究表明:1.3 m锚杆锚固力在25 kN左右,1.8 m锚杆锚固力在33 kN左右,深部采区应优先选用1.8 m及以上的锚杆进行支护;不同位置锚固力差别较大,推测是不同位置岩体质量不同所致,应加强矿区岩体质量分级研究,根据分级结果进一步优选锚杆支护参数。 展开更多
关键词 千米采深 管缝锚杆 拉拔试验 支护评测
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National Survey of Attitudes and Practices of Endotracheal Tube Management in Infants and Small Children in Japan
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作者 Masayuki Shibasaki Yasuyuki Suzuki +3 位作者 Tetsuro Kagawa Yasuhiro Kogure Keiichiro Mizuno Nobuaki Shime 《Open Journal of Anesthesiology》 2019年第2期9-22,共14页
Background: Surveys of pediatric endotracheal tube (ETT) management previously reported that specialists in pediatric anesthesia and intensive care medicine preferred to use uncuffed ETTs for children younger than 8 t... Background: Surveys of pediatric endotracheal tube (ETT) management previously reported that specialists in pediatric anesthesia and intensive care medicine preferred to use uncuffed ETTs for children younger than 8 to 10 years of age. The aim of this study was to reveal the most recent attitudes and clinical practices of pediatric ETT management in Japan. Methods: The attitudes and clinical practices of pediatric ETT management were investigated using the data sheets of each institution and each patient. The data sheets contained information on patient characteristics and type of hospital, surgical procedures, devices used for intubation, and ETT information including types, size, depth, intracuff pressure (ICP), interval of ICP measurement, laryngeal packing, ETT exchange, airway complications, and reintubations. Results: The response rate of this survey was 66.7%. More than half of children older than 2 years of age were intubated with cuffed ETTs;83.5% of cuffed ETTs were used with the cuffs inflated, and ICP was measured in 80.7% of cuffed ETTs. More than half of ICP measurements were only taken at the time of intubation. Post-extubation stridor was rarely observed in cuffed (0.4%) or uncuffed ETTs (1.2%). The pediatric ETT management questionnaire revealed age-based size selection, differences in pressure of air leakage between cuffed (15 - 20 cmH2O) and uncuffed ETTs (20 - 30 cmH2O) of different sizes, the depthmarking method of insertion length. Continuous measurement of ICP was not common. Conclusion: This study revealed widespread use of cuffed ETTs in children older than 2 years of age, rarely occurrence of post-extubation stridor, inflation of cuffs, and practice of ICP measurement. 展开更多
关键词 Cuffed ENDOTRACHEAL tube Size Selection depth Determination Intracuff Pressure INFANTS SMALL CHILDREN
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蜂窝钢管混凝土抗侵彻性能实验研究 被引量:1
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作者 赵宏远 武海军 +2 位作者 董恒 吕映庆 黄风雷 《爆炸与冲击》 EI CAS CSCD 北大核心 2023年第5期44-54,共11页
为了研究蜂窝钢管混凝土的抗侵彻性能,采用125 mm口径滑膛炮开展了蜂窝钢管混凝土靶侵彻实验共6发,获得了不同工况时靶板破坏形态及侵深数据,分析了蜂窝钢管混凝土的典型破坏形式,对比了不同弹靶尺寸因数时靶板破坏形式的区别以及着靶... 为了研究蜂窝钢管混凝土的抗侵彻性能,采用125 mm口径滑膛炮开展了蜂窝钢管混凝土靶侵彻实验共6发,获得了不同工况时靶板破坏形态及侵深数据,分析了蜂窝钢管混凝土的典型破坏形式,对比了不同弹靶尺寸因数时靶板破坏形式的区别以及着靶点和钢管壁厚对蜂窝钢管混凝土抗侵彻能力的影响。同时,对7组不同壁厚的六边形钢管混凝土和3组六边形无钢管混凝土柱进行了单轴压缩实验,研究了不同壁厚时六边形钢管对核心混凝土强度及延性的增强效应,拟合了核心混凝土强度增强因数同围箍因数的关系,并改进普通混凝土侵深的经验公式,得到了适用于蜂窝钢管混凝土的最大侵深计算公式。结果表明:钢管壁厚是影响侵深的重要因素,壁厚越大,侵深越小;着靶点位置对侵深的影响较复杂,具有离散性;着靶点位置对靶体表面破坏形式影响较大;钢管可以有效增加核心混凝土的强度和延性;改进后的侵深计算公式可以预测弹体对蜂窝钢管混凝土靶的最大侵深。 展开更多
关键词 抗侵彻性能 125 mm口径滑膛炮 蜂窝钢管混凝土 强度增强效应 侵彻深度
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常州市区污水管道渗漏的试验
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作者 张冬冬 《价值工程》 2023年第8期122-124,共3页
为探寻污水管道的渗漏特性,本文在常州市区选取6处污水管段,采用容积法从管材、管径、管龄、埋深四个方面对其渗漏特性进行了试验研究。研究发现,对于外渗特性,管径越大,渗漏量越大;钢筋混凝土管渗漏量较大,HDPE管和球墨铸铁管渗漏量较... 为探寻污水管道的渗漏特性,本文在常州市区选取6处污水管段,采用容积法从管材、管径、管龄、埋深四个方面对其渗漏特性进行了试验研究。研究发现,对于外渗特性,管径越大,渗漏量越大;钢筋混凝土管渗漏量较大,HDPE管和球墨铸铁管渗漏量较小且相当;大管径的钢筋混凝土管渗漏速率要大于小管径的HDPE管和球墨铸铁管;对于内渗特性,管径越大,渗漏量和渗漏速率越大,但12h内的差距不明显;日间12h内,前6h的渗漏速率大于后6h的渗漏速率;夜间12h的渗漏速率开始回升。污水管道渗漏量与管龄、埋深有关,管底深度≤5.38m,管道渗漏呈现外渗特性,管底深度≥5.63m,管道渗漏呈现内渗特性。 展开更多
关键词 污水管道 渗漏 管材 管径 管龄 埋深
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钢管混凝土剪力键抗剪性能研究
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作者 史天祥 贾俊峰 +2 位作者 张凯迪 白玉磊 庞伟 《防灾科技学院学报》 2023年第2期40-50,共11页
采用ABAQUS有限元软件建立了钢管混凝土剪力键数值仿真模型,并基于已有试验结果验证了数值建模的正确性;基于验证的模型,讨论钢管预埋深度、径厚比、抗剪栓钉及剪跨比等对钢管混凝土剪力键抗剪性能的影响,并提出了钢管混凝土剪力键抗剪... 采用ABAQUS有限元软件建立了钢管混凝土剪力键数值仿真模型,并基于已有试验结果验证了数值建模的正确性;基于验证的模型,讨论钢管预埋深度、径厚比、抗剪栓钉及剪跨比等对钢管混凝土剪力键抗剪性能的影响,并提出了钢管混凝土剪力键抗剪强度及最小埋深计算方法。研究结果表明:钢管混凝土剪力键接缝直剪强度达到峰值承载力后抗剪强度缓慢下降,具有良好的延性行为。在一定范围内,钢管混凝土剪力键的抗剪承载力随着钢管混凝土剪力键预埋深度增大而增大,随剪跨比增大而减小;钢管截面面积对剪力键的抗剪承载力影响较小;当在钢管混凝土剪力键预埋端设置栓钉后,其抗剪承载力可提高约20%。 展开更多
关键词 钢管混凝土 剪力键 节段拼装桥梁 接缝 抗剪强度 最小埋深
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换热列管折流板部位涡流检测缺陷深度修正
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作者 胡宇路 《西部特种设备》 2023年第4期32-36,58,共6页
尿素高压圈是尿素生产装置的核心部位,操作压力和操作温度较高、腐蚀性强,换热列管易产生缺陷。换热列管常采用多频涡流检测,由于折流板的影响,换热列管折流板部位的缺陷在涡流检测中会变形失真。针对这个问题,采用对比试块模拟研究,并... 尿素高压圈是尿素生产装置的核心部位,操作压力和操作温度较高、腐蚀性强,换热列管易产生缺陷。换热列管常采用多频涡流检测,由于折流板的影响,换热列管折流板部位的缺陷在涡流检测中会变形失真。针对这个问题,采用对比试块模拟研究,并将实际检测中遇到的真实案例进行对比,探究换热列管折流板部位缺陷深度的修正问题。 展开更多
关键词 尿素高压圈 换热列管 多频涡流检测 缺陷深度修正
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平行流蒸发器制冷剂流量分配特性 被引量:9
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作者 赵兰萍 王仁杰 +1 位作者 刘桂兰 杨志刚 《同济大学学报(自然科学版)》 EI CAS CSCD 北大核心 2019年第2期261-268,274,共9页
采用标准k-ε模型和Eulerian模型对平行流蒸发器集管内两相制冷剂分配特性进行模拟,发现在集管加入分流管后,制冷剂流量分配不均匀性得到明显改善.在此基础上,分别对扁管插入集管的深度、分流管开孔率对流量分配的影响情况展开分析.发... 采用标准k-ε模型和Eulerian模型对平行流蒸发器集管内两相制冷剂分配特性进行模拟,发现在集管加入分流管后,制冷剂流量分配不均匀性得到明显改善.在此基础上,分别对扁管插入集管的深度、分流管开孔率对流量分配的影响情况展开分析.发现当扁管伸入集管深度大约在分流管下方1/2时流量分配均匀性最好;对比不同开孔率时的流量分配情况,发现随着开孔率的增大流量分配均匀性先变差后变好,之后随着开孔率进一步增大,流量分配均匀性又变差.分流管在小开孔率下,需要注意与制冷系统中节流阀的匹配. 展开更多
关键词 平行流蒸发器 计算流体力学 两相流 分流管 扁管插入深度 开孔率
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微润灌管带埋深及压力水头对土壤水分累积入渗量的影响与模拟 被引量:7
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作者 张少文 郭向红 +2 位作者 毕远杰 雷涛 雷明杰 《节水灌溉》 北大核心 2018年第3期19-22,26,共5页
微润灌是一种全新的低能耗节水灌溉技术,应用前景广阔。为了揭示微润灌管带埋深及压力水头对累积入渗量的影响,采用室内土箱试验,对不同管带埋深(D5、D10、D15、D20)与压力水头(H100、H150、H200)条件下的水分入渗过程进行了研究。结果... 微润灌是一种全新的低能耗节水灌溉技术,应用前景广阔。为了揭示微润灌管带埋深及压力水头对累积入渗量的影响,采用室内土箱试验,对不同管带埋深(D5、D10、D15、D20)与压力水头(H100、H150、H200)条件下的水分入渗过程进行了研究。结果表明:不同压力水头处理后的累积入渗量大小表现为:H200>H150>H100,不同埋深处理后的累积入渗量大小表现为:D5>D10>D15>D20,埋深、压力水头及两者间的交互效应对总累积入渗量的影响均达到极显著水平。微润灌累积入渗量变化过程符合Kostiakov模型,压力水头与模型入渗系数、入渗指数呈正相关关系,而管带埋深与模型入渗系数、入渗指数呈负相关关系,管带埋深与压力水头间的交互效应对入渗系数和入渗指数存在极显著影响。进一步分析发现,管带埋深、压力水头与入渗系数之间的关系分别符合线性函数和指数函数,而与入渗指数之间的关系均符合指数函数,将其代入Kostiakov模型,建立了管带埋深与压力水头双因素耦合条件下的微润灌累积入渗量模型DH-K(Kostiakov修正模型)。经验证,DH-K模型的平均相对误差MAPE仅为3.97%,模拟精度较高,可用于微润灌管带埋深与压力水头双因素耦合条件下的累积入渗量预测。 展开更多
关键词 微润灌 管带埋深 压力水头 入渗
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连续油管最大下入深度问题初探 被引量:20
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作者 刘亚明 于永南 仇伟德 《石油机械》 北大核心 2000年第1期9-12,共4页
在油田使用连续油管柱作业中,求解连续油管的最大下入深度问题时,必须满足最大抗拉强度条件、摩擦阻力条件和屈曲变形条件及其确定的方法和原则。而在下入过程中摩擦综合阻力又是求解的关键。求解摩阻力时,可针对连续油管在井身中不同... 在油田使用连续油管柱作业中,求解连续油管的最大下入深度问题时,必须满足最大抗拉强度条件、摩擦阻力条件和屈曲变形条件及其确定的方法和原则。而在下入过程中摩擦综合阻力又是求解的关键。求解摩阻力时,可针对连续油管在井身中不同结构段的不同变形形状,采用求解径向接触反力时求一个螺距内平均接触反力的方法加以解决。按照这种方法,采用安全计算工况,对新疆石油管理局八一井区8607侧钻水平井进行了连续油管冲砂作业时最大下入深度的编程计算,计算结果表明,连续油管的下入深度可满足侧钻水平井冲砂工艺要求。 展开更多
关键词 连续油管 下入深度 计算 冲砂 侧钻 水平井 钻井
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U型管换热性能影响因素研究 被引量:7
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作者 杨昌智 黄兵 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2009年第S2期44-48,共5页
建立了钻井单位井深换热量与钻井深度、流量变化关系的计算模型.通过实例计算,分析了在流量不变时钻井的单位井深换热量随钻井深度的变化以及50 m,100 m,150m和200 m钻井单位井深换热量随流量的变化.得出在设计地源热泵地下换热器时,需... 建立了钻井单位井深换热量与钻井深度、流量变化关系的计算模型.通过实例计算,分析了在流量不变时钻井的单位井深换热量随钻井深度的变化以及50 m,100 m,150m和200 m钻井单位井深换热量随流量的变化.得出在设计地源热泵地下换热器时,需要合理的选择钻井深度、U型管内的流体流量来保证钻井的换热经济性.最后提出单位井深换热成本指数作为U型管换热经济性评价指标. 展开更多
关键词 U型管 钻井深度 流量 换热成本
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尾水管深度对轴流定桨式水轮机性能的影响 被引量:4
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作者 杨静 宋华婷 +2 位作者 黄智达 刘健 王正伟 《农业机械学报》 EI CAS CSCD 北大核心 2016年第2期45-50,共6页
尾水管深度对水轮机的效率及稳定性都有重要影响。为解决某电站水轮机效率及出力不足的问题,采用数值模拟的方法,分析了尾水管深度变化对水轮机性能的影响。通过几个不同尾水管加深方案的比较分析,得出尾水管深度在一定范围内增加能有... 尾水管深度对水轮机的效率及稳定性都有重要影响。为解决某电站水轮机效率及出力不足的问题,采用数值模拟的方法,分析了尾水管深度变化对水轮机性能的影响。通过几个不同尾水管加深方案的比较分析,得出尾水管深度在一定范围内增加能有效提高尾水管回能系数,降低扩散损失。但由于沿程摩擦损失会随深度增加而增大,因而综合考虑损失、效率及经济性因素,最终选定尾水管深度为3.0D1的尾水管深度方案。同时,为保证水轮机的运行稳定性,也比较了该方案对流场稳定性的影响,分析了湍动能及脉动的变化。结果表明尾水管与转轮内流场存在相互作用,直锥段加高后不但会降低直锥段出口的湍动能,也会减轻转轮出口的湍动能。即尾水管内流动的改善也会降低转轮出口附近流场的紊乱程度,显著降低了转轮所受到的径向力及压力脉动峰峰值,提升了转轮内流场的稳定性。此外尾水管深度改变方案对转轮空化性能的影响不大,转轮叶片背面的最低压力范围基本没有变化。 展开更多
关键词 轴流定桨式水轮机 尾水管深度 回能系数 损失分析 数值模拟
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