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甲胺泵管路振动故障分析 被引量:1
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作者 郑水英 刘淑莲 《振动工程学报》 EI CSCD 北大核心 2004年第z1期388-390,共3页
对某炼化厂的高压甲胺泵的管路振动进行了测试分析,通过对各个管路系统的不同测点的振动频谱分析,给出了导致甲胺泵管路振动过大的起因是压力脉动频率与管线的固有频率接近的结果,提出了相应的减振措施.
关键词 管流脉动 甲胺泵管路
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Laser diode drive method with narrow-width and high-peak current for multi-line LIDAR 被引量:2
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作者 LI Xu DUAN Fa-jie +3 位作者 MA Ling WANG Xian-quan JIANG Jia-jia FU Xiao 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2019年第3期246-253,共8页
Light detection and ranging (LIDAR) based on time of flight (TOF) method is widely used in many fields related to distance measurement. LIDAR generally uses laser diode (LD) to emit the pulsed laser with high peak pow... Light detection and ranging (LIDAR) based on time of flight (TOF) method is widely used in many fields related to distance measurement. LIDAR generally uses laser diode (LD) to emit the pulsed laser with high peak power and short duration to ensure a large distance measurement range and eye safety. To achieve this goal, we propose a pulsed LD drive method producing the drive current with high peak and narrow pulse width. We analyze the key issues and related theories of the drive current generation based on this method and design an LD driver. A model of drive current generation is established and the influence of operating frequency on drive current is discussed. The LD driver is simulated by software and verified by experiments. The working frequency of the driver changes from 20 kHz to 100 kHz and the charging voltage is set at 130 V. The current produced by this driver has a duration of 8.8 ns and a peak of about 35 A, and the peak output optical power of the LD exceeds 75 W. 展开更多
关键词 light detection and ranging(LIDAR) distance measurement laser diode (LD) driver pulsed current
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The effect of slow deep breathing relaxation exercise on pain levels during and post chest tube removal after coronary artery bypass graft surgery 被引量:3
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作者 Mohamad I.Jarrah Issa M.Hweidi +5 位作者 Sirin A.Al-Dolat Hossam N.Alhawatmeh Salwa M.Al-Obeisat Lama I.Hweidi Aysam I.Hweidi Osama A.Alkouri 《International Journal of Nursing Sciences》 CSCD 2022年第2期155-161,I0003,共8页
Objectives:This study aimed to evaluate the effectiveness of slow deep breathing relaxation exercise(SDBRE)in reducing patients’pain levels during chest tube removal(CTR)post coronary artery bypass grafting(CABG)surg... Objectives:This study aimed to evaluate the effectiveness of slow deep breathing relaxation exercise(SDBRE)in reducing patients’pain levels during chest tube removal(CTR)post coronary artery bypass grafting(CABG)surgery.Methods:In 2019,fifty post-CABG patients were conveniently selected from a cardiac intensive care unit in Jordan’s major referral heart institute.The patients were randomly assigned to either an intervention group or a control group.A total of 25 patients were assigned into the experimental group who received slow deep breathing relaxation Exercise(SDBRE)alongside the conventional care before CTR.The remaining 25 patients constituted the control group(50%)that had CTR following conventional care.The Visual Analogue Scale(VAS)was used to measure the participants’pain levels during three phases:before CTR(Time 1),5-min post CTR(Time 2),and 15-min post CTR(Time 2)to compare the intervention effect between the two groups.Results:The data analysis findings for the control and intervention group of patients showed that there was a statistically significant decline in their pain level across time for both groups(H¼32.71,P<0.01;H=47.23,P<0.01)respectively.The intervention group had significantly lower pain levels than the control group at Time 2(3.50[1.20,5.30]vs.7.90[7.00,9.00],P<0.01)and Time 3(0.00[0.00,1.30]vs.3.60[2.40,4.10]P<0.01).Conclusions:Using SDBRE during CTR is an effective technique for reducing pain which can minimize the need for analgesics and their associated adverse effects. 展开更多
关键词 Breathing exercises Chest tubes removal Coronary artery bypass grafting PAIN Patients JORDAN
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Hemodynamics in the portal vein evaluated by pulse wave Doppler ultrasonography in patients with chronic hepatitis C treated with interferon 被引量:1
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作者 Shigeo Nakanishi Katsuya Shiraki +3 位作者 Kouji Yamamoto Mutsumi Koyama Noboru Kimura Takeshi Nakano 《World Journal of Gastroenterology》 SCIE CAS CSCD 2005年第3期396-399,共4页
AIM: To employ pulse wave Doppler ultrasonography to evaluate the changes in portal blood flow velocity in patients with chronic hepatitis C (CHC) receiving interferon (IFN) treatment. METHODS: The subjects in this st... AIM: To employ pulse wave Doppler ultrasonography to evaluate the changes in portal blood flow velocity in patients with chronic hepatitis C (CHC) receiving interferon (IFN) treatment. METHODS: The subjects in this study were 14 patients (13 men and l woman) with CHC who received IFN treatment. Portal blood flow velocity was measured in the vessels at the porta hepatis at four time points: before IFN administration (pre-IFN), 2 wk after the start of administration (wk 2), 24 wk after the start of administration (wk 24, i.e., the end of IFN administration), and 24 wk after the end of administration (wk 48). RESULTS: The patients with CHC in whom IFN treatment resulted in complete elimination or effective elimination of viruses showed a significant increase in portal blood flow velocity at the end of IFN treatment compared with that before IFN treatment. In contrast, when IFN was ineffective, no significant increase in portal blood flow velocity was observed at wk 24 or 48 compared with the pre-IFN value. In addition, the patients with CHC in whom IFN was ineffective showed significantly lower portal blood flow velocity values than control subjects at all measurement time points. CONCLUSION: Pulse wave Doppler ultrasonography is a noninvasive and easily performed method for evaluating the effects of IFN treatment in patients with CHC. This technique is useful for measuring portal blood flow velocity before and 24 wk after IFN administration in order to evaluate the changes over time, thus assessing the effectiveness of IFN treatment. 展开更多
关键词 Chronic Hepatitis C INTERFERON Pulsed-wave Doppler ultrasonography Portal Vein HEMODYNAMICS
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Prevalence of linked angina and gastroesophageal reflux disease in general practice 被引量:5
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作者 Hirohito Kato Takamasa Ishii +2 位作者 Tatsuo Akimoto Yoshihisa Urita Motonobu Sugimoto 《World Journal of Gastroenterology》 SCIE CAS CSCD 2009年第14期1764-1768,共5页
AIM: To evaluate the association between gastroesophageal reflux diseases (GERD) and coronary heart diseases. METHODS: One thousand nine hundred and seventy consecutive patients who attended our hospital were enro... AIM: To evaluate the association between gastroesophageal reflux diseases (GERD) and coronary heart diseases. METHODS: One thousand nine hundred and seventy consecutive patients who attended our hospital were enrolled. All of the patients who first attend our hospital were asked to respond to the F-scale questionnaire regardless of their chief complaints. All patients had a careful history taken, and resting echocardiography (ECG) was performed by physicians if the diagnostic necessity arose. Patients with ECG signs of coronary artery ischemia were defined as ST- segment depression based on the Minnesota code. RESULTS: Among 712 patients (36%) with GERD, ECG was performed in 171 (24%), and ischemic changes were detected in eight (5%). Four (50%) of these patients with abnormal findings upon ECG had no chest symptoms such as chest pain, chest oppression, or palpitations. These patients (0.6%; 4/712) were thought to have non-GERD heartburn, which may be related to ischemic heart disease. Of 281 patients who underwent ECG and did not have GERD symptoms, 20 (7%) had abnormal findings upon ECG. In patients with GERD symptoms and ECG signs of coronary artery ischemia, the prevalence of linked angina was considered to be 0.4% (8/1970 patients).CONCLUSION: The present study suggested that ischemic heart disease might be found although a patient was referred to the hospital with a complaint of GERD symptoms. Physicians have to be concerned about missing clinically important coronary artery disease while evaluating patients for GERD symptoms. 展开更多
关键词 Linked angina EPIDEMIOLOGY Generalpractice ELECTROCARDIOGRAPHY Gastroesophageal reflexdisease
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Lattice Boltzmann Simulation of One Particle Migrating in a Pulsating Flow in Microvessel
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作者 邱冰 谭惠丽 李华兵 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第10期756-760,共5页
A lattice Boltzmann model of two dimensions is used to simulate the movement of a single rigid particle suspended in a pulsating flow in micro vessel The particle is as big as a red blood cell, and the micro vessel is... A lattice Boltzmann model of two dimensions is used to simulate the movement of a single rigid particle suspended in a pulsating flow in micro vessel The particle is as big as a red blood cell, and the micro vessel is four times as wide as the diameter of the particle. It is found that Segrd-Silberberg effect will not respond to the pulsation of the flow when the Reynolds number is relatively high. However, when the Reynolds number is low enough, Segrd-Silberberg effect disappears. In the steady flow, different initial position leads to different equilibrium positions. In a pulsating flow, different frequencies of pulsation also cause different equilibrium positions. Particularly, when the frequency of pulsation is closed to the human heart rate, Segrd-Silberberg effect presents again. The evolutions of velocity, rotation, and trajectory of the particle are investigated to find the dynamics of such abnormal phenomenon. 展开更多
关键词 Segre Silberberg effect lattice Boltzmann method red blood cell pulsating flow
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Residence Time Distribution at Laminar Pulsatile Flow in a Straight Pipe
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作者 Pavel Novotny Rudolf Zitny Hynek Chlup Jakub Kronek David Hromadka 《Journal of Chemistry and Chemical Engineering》 2011年第4期358-368,共11页
This paper deals with the problem of theoretical identification of the residence time distribution (RTD) characteristics of a straight pipe at laminar pulsatile flow, if tracer diffusion can be neglected. This situa... This paper deals with the problem of theoretical identification of the residence time distribution (RTD) characteristics of a straight pipe at laminar pulsatile flow, if tracer diffusion can be neglected. This situation is typical for micro-apparatuses (e.g. fluidic element) and also for flow in large arteries. Residence time distribution based on velocity profiles at pulsatile flow of a Newtonian liquid in a rigid pipe will be derived theoretically and compared with the well known results for a constant flow rate E(τ) = τ-^2/2τ^3 at τ 〉 τ^-/2, where E (τ) is differential distribution, x is residence time and τ^- is the mean residence time. The following part of the paper deals stimulus response experimental techniques using tracers. The principal problem related to laminar and convection dominated pulsatile flows is discussed: Can the impulse response also be identified with the actual residence time distribution in the case of variable flow? The general answer is no, and differences between RTD and impulse responses are evaluated as a function of the frequency and amplitude of pulsatile flows. 展开更多
关键词 Convective flow regime impulse response pulsatile flow residence time distribution
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Determination of arterial wall shear stress 被引量:3
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作者 柳兆荣 何烽 +1 位作者 徐刚 陈泳 《Science China Mathematics》 SCIE 2001年第10期1312-1321,共10页
The arteries can remodel their structure and function to adapt themselves to the mechanical environment. In various factors that lead to vascular remodeling, the shear stress on the arterial wall induced by the blood ... The arteries can remodel their structure and function to adapt themselves to the mechanical environment. In various factors that lead to vascular remodeling, the shear stress on the arterial wall induced by the blood flow is of great importance. However, there are many technique difficulties in measuring the wall shear stress directly at present. In this paper, through analyzing the pulsatile blood flow in arteries, a method has been proposed that can determine the wall shear stress quantitatively by measuring the velocity on the arterial axis, and that provides a necessary means to discuss the influence of arterial wall shear stress on vascular remodeling. 展开更多
关键词 shear stress vascular remodeling pulsatile flow HYPERTENSION
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An Experimental Investigation on Heat Transfer Performance of Nanofluid Pulsating Heat Pipe 被引量:8
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作者 Hongwei Jia Li Jia Zetao Tan 《Journal of Thermal Science》 SCIE EI CAS CSCD 2013年第5期484-490,共7页
The effect of SiO2 particles on heat transfer performance of a pulsating heat pipe (PHP) was investigated experi- mentally. DI water was used as the base fluid and contrast medium for the PHP. In order to study and ... The effect of SiO2 particles on heat transfer performance of a pulsating heat pipe (PHP) was investigated experi- mentally. DI water was used as the base fluid and contrast medium for the PHP. In order to study and measure the character, there are SiO2/H20 nanofluids with different concentration and applying with various heating powers during the experiment investigation. According to the experimental result, the high fraction of SiO2/H20 will de- teriorate the performance of PHP compared with DI water, i.e. the thermal resistance and the temperature of evaporation section increases. It is in contrary in the case of low fraction of SiO2/H20. Finally, the comparison of the thermal performances between the normal operation system and the static settlement system is given. It is found that both the thermal resistance of nanofluid PHP and the temperature of the evaporation section increase after standing for a period, and it is the same trend for the temperature fluctuation at the identical heating power for PHP. 展开更多
关键词 NANOFLUID Pulsating heat pipe Heat transfer characteristics Suspension characteristics
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FLOW OF MICROPOLAR FLUID THROUGH CATHETERIZED ARTERY -- A MATHEMATICAL MODEL 被引量:1
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作者 D.SRINIVASACHARYA D.SRIKANTH 《International Journal of Biomathematics》 2012年第2期61-72,共12页
In this paper, the flow of blood through catheterized artery with mild constriction at the outer wall is considered. The closed form solutions are obtained for velocity and microrotation components. The impedance (re... In this paper, the flow of blood through catheterized artery with mild constriction at the outer wall is considered. The closed form solutions are obtained for velocity and microrotation components. The impedance (resistance to the flow) and wall shear stress are calculated. The effects of catheterization, coupling number, micropolar parameter, and height of the stenosis on impedance and wall shear stresses are discussed. 展开更多
关键词 STENOSIS CATHETER micropolar fluid IMPEDANCE wall shear stress.
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Advance in research of several types of streaming of pulse tube refrigerators 被引量:1
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作者 GU Chao TANG JianBo +1 位作者 WANG JunJie ZHOU Yuan 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第11期2690-2701,共12页
The pulse tube refrigerator (PTR) is a promising small-scale cryocooler. This paper first briefly introduces the history of the pulse tube refrigerator. It has pointed out that technology improvements and theoretica... The pulse tube refrigerator (PTR) is a promising small-scale cryocooler. This paper first briefly introduces the history of the pulse tube refrigerator. It has pointed out that technology improvements and theoretical developments of the pulse tube refrig- erator closely relate with the internal streaming effects. Then the discovering history and classification of the streaming or DC (direct current) flow effect are summarized. It proposes for the first time that the physical significance of the streaming con- tains the driving mechanisms and the transport mechanisms. It demonstrates that the driving mechanisms are the asymmetry of fluid flow and temperature while the transport mechanisms are a loop or vorticity, which transmits nonlinear dissipations. The important advancements have been made over the past two decades all over the world in research of streaming of the pulse tube refrigerator including Gedeon DC flow, Rayleigb streaming, the third type of DC flow and the regenerator circulation. With regard to Gedeon DC flow, theoretical and experimental analyses have been made and different suppression methods are summarized. In the aspect of Rayleigh streaming, it mainly focuses on the analytical solution of the second-order mass flow and the research of tapered pulse tubes. In particular, limited research on the third type of DC flow and regenerator circulation is presented. The experimental measurement techniques of streaming also are summarized. Finally, this paper briefly discusses the key scientific and technical issues of the current research, and foretells the future development trends of streaming research in PTR. 展开更多
关键词 pulse tube refrigerator STREAMING asymmetry closed loop VORTICITY
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Effects of stenoses on non-Newtonian flow of blood in blood vessels 被引量:1
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作者 Om Prakash O. D. Makinde +2 位作者 S. P. Singh Nidhi Jain Devendra Kumar 《International Journal of Biomathematics》 2015年第1期123-135,共13页
In this paper, a mathematical model for steady blood flow through blood vessels with uniform cross-section in stenoses arteries has been proposed. Blood is assumed to be non- Newtonian, incompressible and homogeneous ... In this paper, a mathematical model for steady blood flow through blood vessels with uniform cross-section in stenoses arteries has been proposed. Blood is assumed to be non- Newtonian, incompressible and homogeneous fluid. Blood in human artery is represented as Bingham plastic fluid. Expressions for flow rate, wall shear stress, and resistance to flow against stenoses size have been obtained. Obtained results indicate that stenoses size decreases the flow rate and increases the wall shear stress as well as resistance to flow. 展开更多
关键词 Stenoses wall shear stress resistance to flow flow rate non-Newtonian fluid
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A SUSPENSION MODEL FOR BLOOD FLOW THROUGH A CATHETERIZED ARTERY
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作者 SHAILESH MISHRA NARENDRA KUMAR VERMA S. U. SIDDIQUI 《International Journal of Biomathematics》 2012年第5期21-35,共15页
The present work is concerned with the analysis of an axi-symmetric flow of blood through coaxial tubes where the outer tube has an axially symmetric mild stenosis and the inner tube has a balloon which is axi-symmetr... The present work is concerned with the analysis of an axi-symmetric flow of blood through coaxial tubes where the outer tube has an axially symmetric mild stenosis and the inner tube has a balloon which is axi-symmetric in nature. The mild stenosis approximation is used to solve the present problem. The effect of the volume fraction density of the particles, the maximum height attained by the balloon, the radius of the inner tube, which keeps the balloon in position k, and the axial displacement of the balloon have been studied. Flow parameters such as the resistive impedance, the wall shear stress distribution in the stenotic region and its magnitude at the stenosis throat have been computed for different parameters. It is observed that the resistance to flow decreases with increasing values of the axial displacement of the balloon, while the resistance to flow increases with the volume fraction density of the particles, the radius of the inner tube, which keeps the balloon in position k, and the maximum height attained by the balloon. The wall shear stress distribution in the stenotic region possesses a character similar to the resistance to flow with respect to any parameter. 展开更多
关键词 Blood now STENOSIS resistive impedance wall shear stress suspension.
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