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用变压吸附法提纯氢气,如何通过压力曲线变化分析和判断故障程控阀 预览
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作者 庞新胜 《广东化工》 CAS 2019年第3期118-119,共2页
变压吸附法是现代石油化工普遍使用的从气体中提取氢气的一种方法。其中的压力变化影响着氢气的质量和产量,而控制压力变化的程控阀门又是整个装置生产氢气的主要部件,故程控阀的故障影响着氢气的产量和质量;用何种方法迅速的判断和检... 变压吸附法是现代石油化工普遍使用的从气体中提取氢气的一种方法。其中的压力变化影响着氢气的质量和产量,而控制压力变化的程控阀门又是整个装置生产氢气的主要部件,故程控阀的故障影响着氢气的产量和质量;用何种方法迅速的判断和检验故障程控阀是提高生产效率的关键。 展开更多
关键词 吸附罐 程控阀 压力 压力曲线 压力被拉升 压力被降低 闸阀
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Comparison of walking quality variables between incomplete spinal cord injury patients and healthy subjects by using a footscan plantar pressure system 预览
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作者 Xiang-Nan Yuan Wei-Di Liang +4 位作者 Feng-Hua Zhou Han-Ting Li Li-Xin Zhang Zhi-Qiang Zhang Jian-Jun Li 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第2期354-360,共7页
The main goal of spinal cord rehabilitation is to restore walking ability and improve walking quality after spinal cord injury (SCI). The spatiotemporal parameters of walking and the parameters of plantar pressure can... The main goal of spinal cord rehabilitation is to restore walking ability and improve walking quality after spinal cord injury (SCI). The spatiotemporal parameters of walking and the parameters of plantar pressure can be obtained using a plantar pressure analysis system. Previous studies have reported step asymmetry in patients with bilateral SCI. However, the asymmetry of other parameters in patients with SCI has not been reported. This was a prospective, cross-sectional study, which included 23 patients with SCI, aged 48.1 ± 14.5 years, and 28 healthy subjects, aged 47.1 ± 9.8 years. All subjects underwent bare foot walking on a plantar pressure measurement device to measure walking speed and spatiotemporal parameters. Compared with healthy subjects, SCI patients had slower walking speed, longer stride time and stance time, larger stance phase percentage, and shorter stride length. The peak pressures under the metatarsal heads and toe were lower in SCI patients than in healthy subjects. In the heel, regional impulse and the contact area percentage in SCI patients were higher than those in healthy subjects. The symmetry indexes of stance time, step length, maximum force, impulse and contact area were increased in SCI patients, indicating a decline in symmetry. The results confirm that the gait quality, including spatiotemporal variables and plantar pressure parameters, and symmetry index were lower in SCI patients compared with healthy subjects. Plantar pressure parameters and symmetry index could be sensitive quantitative parameters to improve gait quality of SCI patients. The protocols were approved by the Clinical Research Ethics Committee of Shengjing Hospital of China Medical University (approval No. 2015PS54J) on August 13, 2015. This trial was registered in the ISRCTN Registry (ISRCTN42544587) on August 22, 2018. Protocol version: 1.0. 展开更多
关键词 nerve REGENERATION spinal cord injury WALKING gait QUALITY PLANTAR PRESSURE SYSTEM PLANTAR PRESSURE distribution speed PLANTAR PRESSURE impulse contact area symmetry index neural REGENERATION
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导管压装过程及压装力影响因素探析 预览
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作者 熊强强 孙庆 +1 位作者 柳佳深 雷冲 《汽车科技》 2019年第1期96-99,共4页
用伺服压机进行缸盖导管阀座压装,可以采集整个压装过程中的压装力-位移曲线。压装力是导管压装工序中重要监控参数,在压装过程中,异常情况都会伴随出现压装力过大或者过小的现象,所以利用压装力位移曲线监控压装过程中压装力变化是保... 用伺服压机进行缸盖导管阀座压装,可以采集整个压装过程中的压装力-位移曲线。压装力是导管压装工序中重要监控参数,在压装过程中,异常情况都会伴随出现压装力过大或者过小的现象,所以利用压装力位移曲线监控压装过程中压装力变化是保证导管压装质量的关键。本论文结合压力位移曲线对导管压装过程中各阶段进行分析,并通过在不同条件下进行导管压装实验,得出不同条件下最大压装力变化情况,总结出过盈量、压装前润滑、压装速度对导管压装的影响。 展开更多
关键词 导管 压装力 压力位移曲线 过盈量 压装前润滑 压装速度
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不对称花键啮合齿对锁环式同步器换挡平顺改善分析 预览
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作者 魏小强 《汽车科技》 2019年第1期100-104,共5页
目前锁环式同步器对称结构的花键啮合齿存在换挡二次冲击问题,BP在同歩器同步结束滑套与结合齿圈啮合时会产生过大的换挡冲击,在变速器上反映出挂档有顿挫、卡滞等不顺畅感觉,造成换挡舒适性降低,增加了司机驾驶换挡强度。并且锁环式同... 目前锁环式同步器对称结构的花键啮合齿存在换挡二次冲击问题,BP在同歩器同步结束滑套与结合齿圈啮合时会产生过大的换挡冲击,在变速器上反映出挂档有顿挫、卡滞等不顺畅感觉,造成换挡舒适性降低,增加了司机驾驶换挡强度。并且锁环式同步器二次冲击较大会产生噪音,影响变速器的整体性能。本文是在锁环式同歩器的基础上,改变锁环式同步器滑套、同步环、结合齿圈的花键啮合齿,将花键两侧的啮合齿面设计成不对称结构,并根据同步器在变速器中使用的情况,考虑工作原理将不对称度适当增加,在不影响使用寿命和可靠性的基础上,可显著提高锁止可靠性,保证同步器具有的同步传扭功能。另外在啮合齿与倒锥齿连接位置增加过渡圆角或倒角,这为换档力的逐步过渡提供了结构基础,可保证换档的平稳顺畅。 展开更多
关键词 不对称花键 啮合齿 二次冲击 锁环式 同步器
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Predictive Value of Resting Pd/Pa for Fractional Flow Reserve Assessed with Monorail Pressure Microcatheter in Real-World Practice 预览
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作者 Keng Tat Koh Asri Said +11 位作者 Khaw Chee Sin Oon Yen Yee Erwin Mulia Tan Chen Ting Francis Shu Eng Pbeng Ho Kian Hui Voon Chi Yen Cham Yee Ling Khiew Ning Zan Nor Hanim Mohd Amin Alan Fong Yean Yip Ong Tiong Kiam 《心血管创新与应用》 2019年第B07期113-120,共8页
Background and Objectives:The aims of this study were(1)to examine the diagnostic accuracy of resting timeaveraged distal coronary pressure(Pd)to mean aortic pressure(Pa)ratio to predict hyperemic fractional flow rese... Background and Objectives:The aims of this study were(1)to examine the diagnostic accuracy of resting timeaveraged distal coronary pressure(Pd)to mean aortic pressure(Pa)ratio to predict hyperemic fractional flow reserve(FFR)and(2)to identify a resting Pd/Pa value that can preclude the need for hyperemic FFR assessed with use of a monorail pressure catheter.Methods:A total of 191 stenoses were assessed.After exclusions,157 FFR data sets from 103 patients were analyzed.Results:Resting Pd/Pa showed poor agreement with hyperemic FFR(r=0.619,P<0.001).The receiver operating characteristic curve for resting Pd/Pa with reference to hyperemic FFR of 0.80 or less showed an area under the curve of 0.800(95%confi dence interval 0.732– 0.868,P<0.001),with the greatest diagnostic accuracy of 74.5%for resting Pd/Pa of less than 0.85.Resting Pd/Pa of 0.96 or greater had a sensitivity of 100%and a negative predictive value of 100%,and resting Pd/Pa of 0.82 or less had a specifi city of 98.9%and a positive predictive value of 94.1%to predict abnormal FFR of 0.80 or less.These results were consistent regardless of the vessels studied,the location of lesions,and the severity of stenosis.Conclusions:Resting Pd/Pa showed poor agreement with hyperemic FFR assessed with use of a monorail pressure microcatheter.However,resting Pd/Pa of 0.96 or greater had excellent sensitivity and negative predictive value to predict normal hyperemic FFR,and resting Pd/Pa of 0.82 or less had excellent specifi city and positive predictive value to predict abnormal hyperemic FFR. 展开更多
关键词 fractional fl ow reserve MONORAIL PRESSURE CATHETER RESTING time-averaged DISTAL coronary PRESSURE to mean aortic PRESSURE ratio
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球形空腔内的粒子对内壁作用力的讨论 预览
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作者 石凤良 李敬林 《大学物理》 2019年第7期23-25,共3页
指出了一道量子力学习题解答的错误,并给出合理的解答,探讨了处于束缚定态的粒子对空腔内壁的平均作用力。
关键词 束缚定态 压力 压强 力的平均值 力的方向
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Prediction Model of Coal Reservoir Pressure and its Implication for the Law of Coal Reservoir Depressurization 预览
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作者 YAN Xinlu ZHANG Songhang +5 位作者 TANG Shuheng LI Zhongcheng WANG Kaifeng YI Yongxiang DANG Feng HU Qiuping 《地质学报:英文版》 SCIE CAS CSCD 2019年第3期692-703,共12页
The main methods of coalbed methane(CBM)development are drainage and depressurization,and a precise prediction of coal reservoir pressure is thus crucial for the evaluation of reservoir potentials and the formulation ... The main methods of coalbed methane(CBM)development are drainage and depressurization,and a precise prediction of coal reservoir pressure is thus crucial for the evaluation of reservoir potentials and the formulation of reasonable development plans.This work established a new reservoir pressure prediction model based on the material balance equation(MBE)of coal reservoir,which considers the self-regulating effects of coal reservoirs and the dynamic change of equivalent drainage area(EDA).According to the proposed model,the reservoir pressure can be predicted based on reservoir condition data and the actual production data of a single well.Compared with traditional reservoir pressure prediction models which regard EDA as a fixed value,the proposed model can better predict the average pressure of reservoirs.Moreover,orthogonal experiments were designed to evaluate the sensitivity of reservoir parameters on the reservoir pressure prediction results of this proposed model.The results show that the saturation of irreducible water is the most sensitive parameter,followed by Langmuir volume and reservoir porosity,and Langmuir pressure is the least sensitive parameter.In addition,the pressure drop of reservoirs is negatively correlated with the saturation of irreducible water and the Langmuir volume,while it is positively correlated with porosity.This work analyzed the reservoir pressure drop characteristics of the CBM wells in the Shizhuangnan Block of the Qinshui Basin,and the results show that the CBM reservoir depressurization can be divided into three types,i.e.,rapidly drop type,medium-term stability type,and slowly drop type.The drainage features of wells were reasonably interpreted based on the comprehensive analysis of the reservoir depressurization type;the latter was coupled to the corresponding permeability dynamic change characteristics,eventually proving the applicability of the proposed model. 展开更多
关键词 coalbed METHANE PRESSURE PREDICTION equivalent drainage area influencing factors PRESSURE DROP types Qinshui Basin
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简析锅炉启动系统疏水扩容器的运行故障 预览
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作者 杨威 邓科 季敏东 《电站辅机》 2019年第1期12-14,27共4页
进入锅炉启动系统扩容器的疏水,存在多样性和疏水时机具有阶段性等特点,而且,设备的排汽环境复杂多变。当疏水扩容器的运行出现异常时,无法快速确定扩容器出现运行异常的原因。针对排大气式启动系统疏水扩容器在电厂运行中常见的扩容器... 进入锅炉启动系统扩容器的疏水,存在多样性和疏水时机具有阶段性等特点,而且,设备的排汽环境复杂多变。当疏水扩容器的运行出现异常时,无法快速确定扩容器出现运行异常的原因。针对排大气式启动系统疏水扩容器在电厂运行中常见的扩容器排汽管道振动、嚣叫、排汽大量带水等问题,提出在扩容器设备顶部进入排汽管道处增加一远传压力信号测点,通过分析计算准确快速的判断扩容器故障产生的原因,并能针对问题提出解决方案和措施,进一步保障电厂启动系统的安全有效运行。 展开更多
关键词 锅炉 启动 疏水 扩容器 故障 压力 排汽 远传信号
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燃气具气密性检测压力要求的识别和处置 预览
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作者 林川红 《日用电器》 2019年第7期34-38,共5页
分析燃气具气密性检测过程中漏率与检测气体压力的关系,确定结构缺陷和强制密封缺陷导致的泄漏,其漏率与检测气体压力之间呈近似线性关系;而自紧密封缺陷导致的泄漏,其漏率则随检测气体压力提高而减少,从而需要针对不同的泄漏机理确定... 分析燃气具气密性检测过程中漏率与检测气体压力的关系,确定结构缺陷和强制密封缺陷导致的泄漏,其漏率与检测气体压力之间呈近似线性关系;而自紧密封缺陷导致的泄漏,其漏率则随检测气体压力提高而减少,从而需要针对不同的泄漏机理确定相应的检测气体压力。指出对于常见的燃气具产品,制订制造过程的气密性检测规程时,应考虑进行至少两次压力不同的检测,以较高的压力检测结构缺陷和强制密封缺陷导致的泄漏,同时,也需要以较低的压力检测自紧密封缺陷导致的泄漏。 展开更多
关键词 燃气具 气密性 检测 漏率 压力 强制密封 自紧密封
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Blood Pressure Variability and Its Relationship with Cognitive Function in Elderly Patients with Essential Hypertension and Type 2 Diabetes 预览
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作者 Man Xu 《老年医学(英文)》 2019年第1期1-7,共7页
Objective: To investigate blood pressure variability of Elder hypertensives with type 2 diabetes and its relationship with cognition. Methods: A total of 143 elderly hypertensives were enrolled and divided into diabet... Objective: To investigate blood pressure variability of Elder hypertensives with type 2 diabetes and its relationship with cognition. Methods: A total of 143 elderly hypertensives were enrolled and divided into diabetic group (59 cases) and non-diabetic group (84 cases). The difference of general clinical characteristics, biochemical parameters, carotid ultrasound, a neuropsychological Scales and 24-hour ambulatory blood pressure (24hABPM) parameters between the two groups of subjects were compared. Then, the two groups (diabetic group and non-diabetic group) were further divided into (Mild cognitive dysfunction) subgroup (MMSE>26) and normal cognition subgroup (MMSE≤26), respectively. On the basis of MMSE scores, the difference of the parameters of ABPM between the two subgroups was analyzed. Results: Compared with the control group, 24hSBP, 24hPP, dSBP, dPP, nSBP, nPP, 24hSSD, dSSD, nSSD, 24hSCV, dSCV and nSCV were significantly higher in the diabetic group (p<0.05). However, cognition was lower in the diabetic group. No significant difference was found in the circadian pattern of blood pressure between the two groups. 24hSSD, dSSD, nSSD, 24hSCV, dSCV, nSCV were significantly higher in the MCI subgroup than normal cognition subgroup in both diabetic and non-diabetic groups(p<0.05), and they were negatively associated with scores of MMSE, the correlation coefficient were -0.235,-0.246,-0.341,-0.158,-0.222,-0.238 (0.001≤P<0.05). Conclusion: The study showed that in the elderly with hypertension, the mean systolic blood pressure and blood pressure variability were both higher in the diabetic group, and the cognition was lower instead. Whether or not with diabetes, blood pressure variability was always higher in the MCI subgroup. Blood pressure variability increased in patients with diabetes, and was associated with cognitive decline. 展开更多
关键词 MILD cognitive DYSFUNCTION BLOOD PRESSURE variability diabetes hypertension 24-hour AMBULATORY BLOOD PRESSURE
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燃烧室压力对燃油喷雾和燃烧的影响研究 预览
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作者 林广涛 潘卫明 +2 位作者 吕田 王圳 兰健 《柴油机》 2019年第3期11-15,共5页
采用CHAMKIN模拟分析燃烧过程,基于自行设计的可视化定压燃烧系统试验研究燃烧室压力对燃油喷雾和燃烧的影响。结果表明:随着压力的升高雾化效果逐渐变差;进气旋流可以改善雾化效果;如果进气旋流是高温气体,则改善情况更明显。压力的增... 采用CHAMKIN模拟分析燃烧过程,基于自行设计的可视化定压燃烧系统试验研究燃烧室压力对燃油喷雾和燃烧的影响。结果表明:随着压力的升高雾化效果逐渐变差;进气旋流可以改善雾化效果;如果进气旋流是高温气体,则改善情况更明显。压力的增加仅加快了反应速率,缩短了着火延迟时间,并没有引起着火过程中温度的很大变化。随着燃烧压力的增加,火焰逐步向燃油喷嘴处移动,可通过提高烟气卷吸率增强气旋效果,使火焰更长,燃烧更均匀,避免烧坏油头及燃烧室内部分温度过高等不良后果。 展开更多
关键词 燃烧室 压力 可视化定压燃烧系统 喷雾 燃烧
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Li-ion battery material under high pressure: amorphization and enhanced conductivity of Li4Ti5O12
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作者 Yanwei Huang Yu He +11 位作者 Howard Sheng Xia Lu Haini Dong Sudeshna Samanta Hongliang Dong Xifeng Li Duck Young Kim Ho-kwang Mao Yuzi Liu Heping Li Hong Li Lin Wang 《国家科学评论:英文版》 CSCD 2019年第2期239-246,共8页
Lithium titanium oxide(Li4Ti5O12,LTO),a‘zero-strain’anode material for lithium-ion batteries,exhibits excellent cycling performance.However,its poor conductivity highly limits its applications.Here,the structural st... Lithium titanium oxide(Li4Ti5O12,LTO),a‘zero-strain’anode material for lithium-ion batteries,exhibits excellent cycling performance.However,its poor conductivity highly limits its applications.Here,the structural stability and conductivity of LTO were studied using in situ high-pressure measurements and first-principles calculations.LTO underwent a pressure-induced amorphization(PIA)at 26.9 GPa.The impedance spectroscopy revealed that the conductivity of LTO improved significantly after amorphization and that the conductivity of decompressed amorphous LTO increased by an order of magnitude compared with its starting phase.Furthermore,our calculations demonstrated that the different compressibility of the Li O6 and Ti O6 octahedra in the structure was crucial for the PIA.The amorphous phase promotes Li+ diffusion and enhances its ionic conductivity by providing defects for ion migration.Our results not only provide an insight into the pressure depended structural properties of a spinel-like material,but also facilitate exploration of the interplay between PIA and conductivity. 展开更多
关键词 high pressure PRESSURE-INDUCED amorphization LITHIUM-ION battery materials IONIC CONDUCTIVITY
Analytical analysis of single-stage pressure relief valves
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作者 Sven Osterland Jurgen Weber 《机电液工程学报》 2019年第1期1-2,共2页
The article presents an explicitly straightforward formulation of the stationary and dynamic behaviour of a pressure relief valve (PRV). This includes an analytical solution for the static p-Q-characteristic, the step... The article presents an explicitly straightforward formulation of the stationary and dynamic behaviour of a pressure relief valve (PRV). This includes an analytical solution for the static p-Q-characteristic, the step and harmonic response and a stability criterion using elementary operations only. It also mathematically proves the intrinsic connection between the gradient of the static p-Q-characteristic and the stability. Thus, the new method offers four main advantages. 展开更多
关键词 SINGLE-STAGE PRESSURE RELIEF valves PRESSURE RELIEF VALVE (PRV) STATIC p-Q-characteristic
一种新型上销的设计与研发 预览
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作者 罗斌 《纺织器材》 2019年第1期16-17,43共3页
为提高纺纱质量,分析现有金属上销和碳纤上销的结构及缺点,研发出SX200型上销,将压力源由片弹簧改为螺旋弹簧,利用旋转调压块等方式实现两档压力可调;通过与SX2-6833型压力棒上销进行试纺C 9.7tex纱对比,说明SX200型上销改善成纱质量较... 为提高纺纱质量,分析现有金属上销和碳纤上销的结构及缺点,研发出SX200型上销,将压力源由片弹簧改为螺旋弹簧,利用旋转调压块等方式实现两档压力可调;通过与SX2-6833型压力棒上销进行试纺C 9.7tex纱对比,说明SX200型上销改善成纱质量较明显。结果表明:SX200型上销钳口压力稳定、可调,使用寿命长,能满足棉纺高端用户的纺纱工艺要求;但其压力档位选择及相应最优化纺纱数据须进一步探索。 展开更多
关键词 上销 钳口 压力 片弹簧 杠杆比原理 螺旋弹簧 调压块
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板坯去毛刺机的改进设计及应用 预览
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作者 郑永平 《福建冶金》 2019年第1期50-52,共3页
本文介绍去毛刺机机构中主要设备组成,详细分析了新型去毛刺机的结构特点和工作原理。阐述了本结构改进后去毛刺机,可靠的'助压式'压推进入去毛刺,修磨处理方法,消除了原机构毛刺不尽的缺点,改进后的本结构设备在生产实际中的... 本文介绍去毛刺机机构中主要设备组成,详细分析了新型去毛刺机的结构特点和工作原理。阐述了本结构改进后去毛刺机,可靠的'助压式'压推进入去毛刺,修磨处理方法,消除了原机构毛刺不尽的缺点,改进后的本结构设备在生产实际中的应用情况及今后的发展趋势。 展开更多
关键词 去毛刺机 结构特点 助压式 压推
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气压疑异时的观测处置
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作者 陈建德 冯燕 +1 位作者 邓建华 张洋飞 《民航学报》 2019年第3期79-81,共3页
修正海平面气压时时对航空器的离地速度和滑跑距离以及飞行高度直接影响,甚至造成飞行事故。而近年来由于气压数据疑异产生的不安全事件却时有发生。为降低差错风险更好地保障飞行安全,本文对工作中常见的气压疑异情况进行分类,逐一分... 修正海平面气压时时对航空器的离地速度和滑跑距离以及飞行高度直接影响,甚至造成飞行事故。而近年来由于气压数据疑异产生的不安全事件却时有发生。为降低差错风险更好地保障飞行安全,本文对工作中常见的气压疑异情况进行分类,逐一分析原因,探讨正确的处置方法。 展开更多
关键词 气压 疑异原因 处置方法
Characteristics of DBD micro-discharge at different pressure and its effect on the performance of oxygen plasma reactor
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作者 刘蕊 俞哲 +2 位作者 曹慧娟 刘璞 张芝涛 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第5期5-13,共9页
The oxygen plasma reactor based on dielectric barrier discharge principle can produce a high concentration of reactive oxygen species,which can cooperate with hydraulic cavitation gas-liquid mixer to realize the appli... The oxygen plasma reactor based on dielectric barrier discharge principle can produce a high concentration of reactive oxygen species,which can cooperate with hydraulic cavitation gas-liquid mixer to realize the application of advanced oxidation technology in water treatment.In this technology,the work pressure of the oxygen plasma reactor is decreased by the vacuum suction effect generated in the snap-back section of the gas-liquid mixed container.In this paper,the characteristics of single micro-discharge at different pressures were investigated with the methods of discharge image,electrical characteristics and spectral diagnosis,in order to analyze the electrical characteristics and reactive oxygen species generation efficiency of oxygen plasma reactor at the pressure range from 60 kPa to 100 kPa.The study indicated that,when the pressure decreases,the duty ratio of ionization in the discharge gap and number of electrons with high energy increases,leading to a rise in reactive oxygen species production.When the oxygen reaches the maximum ionization,the concentration of reactive oxygen species is the highest.Then,the discharge intensity continues to increase,producing more heat,which will decompose the ozone and lower the production of reactive oxygen species.The oxygen plasma reactor has an optimum working pressure at different input powers,which makes the oxygen plasma reactor the most efficient in generating reactive oxygen species. 展开更多
关键词 atmospheric PRESSURE plasma REACTOR PRESSURE active oxygen particle dielectric BARRIER DISCHARGE
Buckling of Cassini Oval Pressure Hulls Subjected to External Pressure 预览
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作者 TANG Wen-xian WANG Wei-min +1 位作者 ZHANG Jian WANG Shu-yan 《中国海洋工程:英文版》 SCIE EI CSCD 2019年第4期503-508,共6页
The paper focuses on Cassini oval pressure hulls under uniform external pressure. The Cassini oval pressure hull is proposed based on the shape index of Cassini oval. The buckling of a series of Cassini oval pressure ... The paper focuses on Cassini oval pressure hulls under uniform external pressure. The Cassini oval pressure hull is proposed based on the shape index of Cassini oval. The buckling of a series of Cassini oval pressure hulls with the shape index of 0.09 0.30 and one spherical pressure hull with the diameter of 2 m is devoted. Such hulls are numerically studied in the case of constant volume, material properties, and wall thickness. The results show that Cassini oval pressure hulls with the shape index of 0.10 0.11 can resist about 4% more external pressure than the spherical one. This deviates from the classical mechanics conclusion that spherical shell is the optimal shape for underwater pressure resistant structures. 展开更多
关键词 PRESSURE HULL CASSINI OVAL shell shape index BUCKLING BEHAVIOUR external PRESSURE
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主蒸汽温度和压力波动对汽轮机转子蠕变疲劳损伤的影响
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作者 赵乃龙 王炜哲 刘应征 《上海交通大学学报》 EI CAS CSCD 北大核心 2019年第2期127-133,共7页
采用Abaqus有限元软件建立了某GW(百万千瓦)级超超临界汽轮机高压转子的轴对称有限元模型,加载基于电厂实际运行的主蒸汽温度和压力的边界条件,以分析转子在稳态运行过程中的力学行为;采用Lemaitre连续损伤力学模型分析高压转子在实际... 采用Abaqus有限元软件建立了某GW(百万千瓦)级超超临界汽轮机高压转子的轴对称有限元模型,加载基于电厂实际运行的主蒸汽温度和压力的边界条件,以分析转子在稳态运行过程中的力学行为;采用Lemaitre连续损伤力学模型分析高压转子在实际运行过程中的蠕变疲劳损伤,并与不考虑主蒸汽温度和压力波动条件下的计算结果进行对比.结果表明:主蒸汽温度和压力的波动对转子的热力状态产生影响;转子的温度和应力随着主蒸汽温度和压力的波动而变化;在转子进汽口位置(A点),主蒸汽温度和压力波动下的蠕变疲劳损伤值超过主蒸汽温度和压力恒定条件下的2倍. 展开更多
关键词 汽轮机 温度 压力 波动 高压转子 蠕变疲劳损伤
Expiratory flow-limitation in mechanically ventilated patients:A risk for ventilator-induced lung injury? 预览
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作者 Antonia Koutsoukou Matteo Pecchiari 《世界重症医学杂志》 2019年第1期1-8,共8页
Expiratory flow limitation(EFL),that is the inability of expiratory flow to increase in spite of an increase of the driving pressure,is a common and unrecognized occurrence during mechanical ventilation in a variety o... Expiratory flow limitation(EFL),that is the inability of expiratory flow to increase in spite of an increase of the driving pressure,is a common and unrecognized occurrence during mechanical ventilation in a variety of intensive care unit conditions.Recent evidence suggests that the presence of EFL is associated with an increase in mortality,at least in acute respiratory distress syndrome(ARDS)patients,and in pulmonary complications in patients undergoing surgery.EFL is a major cause of intrinsic positive end-expiratory pressure(PEEPi),which in ARDS patients is heterogeneously distributed,with a consequent increase of ventilation/perfusion mismatch and reduction of arterial oxygenation.Airway collapse is frequently concomitant to the presence of EFL.When airways close and reopen during tidal ventilation,abnormally high stresses are generated that can damage the bronchiolar epithelium and uncouple small airways from the alveolar septa,possibly generating the small airways abnormalities detected at autopsy in ARDS.Finally,the high stresses and airway distortion generated downstream the choke points may contribute to parenchymal injury,but this possibility is still unproven.PEEP application can abolish EFL,decrease PEEPi heterogeneity,and limit recruitment/derecruitment.Whether increasing PEEP up to EFL disappearance is a useful criterion for PEEP titration can only be determined by future studies. 展开更多
关键词 Expiratory flow-limitation Mechanical ventilation Ventilator-induced lung injury Acute respiratory distress syndrome POSITIVE end-expiratory PRESSURE Intrinsic POSITIVE end-expiratory PRESSURE
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