Effect of Axial Clearance Variation on Dual-Rotor Flowmeter Performance.

This study examines the impact of axial clearance variations on the performance characteristics of a dual-rotor flowmeter (DRT-FM) through numerical simulations, with the validity of the numerical results verified by calibration experiments. The results indicate that within the range of 200 L/h to 1600 L/h, the K factors of different groups increase as clearance increases. The K factor of the 0.80 mm group is the largest, showing an average increase of around 6% compared to that of the 0.50 mm group. Additionally, Linearity E also decreased, with a minimum of 1.07% in the 0.65 mm group, significantly lower than the 3.33% in the 0.50 mm group. Furthermore, the pressure loss increased slightly, with the 0.65 mm group having the largest pressure loss; however, at a flow rate of 1600 L/h, the pressure loss only increases by 0.186 kPa compared to that of the 0.50 mm group. Flow field analysis reveals that changes in axial clearance predominantly affect pressure distribution. Larger clearances reduce low-pressure regions on upstream and downstream transition surfaces, thereby reducing energy loss due to pressure changes. Entropy analysis further demonstrates that higher axial clearance decreases energy loss in the upstream and downstream stationary domains, optimizing the DRT-FM's energy characteristics.

A Compact-Sized Fully Self-Powered Wireless Flowmeter Based on Triboelectric Discharge.

Flow sensing exhibits significant potential for monitoring, controlling, and optimizing processes in industries, resource management, and environmental protection. However, achieving wireless real-time and omnidirectional sensing of gas/liquid flow on a simple, self-contained device without external power support has remained a formidable challenge. In this study, a compact-sized, fully self-powered wireless sensing flowmeter (CSWF) is introduced with a small size diameter of down to less than 50 mm, which can transmit real-time and omnidirectional wireless signals, as driven by a rotating triboelectric nanogenerator (R-TENG). The R-TENG triggers the breakdown discharge of a gas discharge tube (GDT), which enables flow rate wireless sensing through emitted electromagnetic waves. Importantly, the performance of the CSWF is not affected by the R-TENG's varied output, while the transmission distance is greater than 10 m. Real-time wireless remote monitoring of wind speed and water flow rate is successfully demonstrated. This research introduces an approach to achieve a wireless, self-powered environmental monitoring system with a diverse range of potential applications, including prolonged meteorological observations, marine environment monitoring, early warning systems for natural disasters, and remote ecosystem monitoring.

Time Delay Study of Ultrasonic Gas Flowmeters Based on VMD-Hilbert Spectrum and Cross-Correlation.

The accuracy of ultrasonic flowmeter time delay measurement is directly affected by the processing method of the ultrasonic echo signal. This paper proposes a method for estimating the time delay of the ultrasonic gas flowmeter based on the Variational Mode Decomposition (VMD)-Hilbert Spectrum and Cross-Correlation (CC). The method improves the accuracy of the ultrasonic gas flowmeter by enhancing the quality of the echo signal. To denoise forward and reverse ultrasonic echo signals collected at various wind speeds, a Butterworth filter is initially used. The ultrasonic echo signals are then analyzed by Empirical Mode De-composition (EMD) and VMD analysis to obtain the Intrinsic Mode Function (IMF) containing distinct center frequencies, respectively. The Hilbert spectrum time-frequency diagram is used to evaluate the results of the VMD and EMD decompositions. It is found that the IMF decomposed by VMD has a better filtering performance and better anti-interference performance. Therefore, the IMF with a better effect is selected for signal reconstruction. The ultrasonic time delay is then calculated using the Cross-Correlation algorithm. The self-developed ultrasonic gas flowmeter was tested on the experimental platform of the gas flow standard devices using this signal processing method. The results show a maximum indication error of 0.84% within the flow range of 60-606 m3/h, with a repeatability of no more than 0.29%. These results meet the 1-level accuracy requirements as outlined in the national ultrasonic flowmeters calibration regulation JJG1030-2007.

Effect of Orthognathic Surgery On Pulp Blood Flow and Pulp Sensibility: A Prospective Control Trial.

INTRODUCTION: Orthognathic surgery has the potential to compromise the vitality of the teeth. This paper aims to assess changes in pulp blood flow (PBF) and pulp sensibility (PS) of the anterior dentition following orthognathic surgery and to assess the influence of the proximity of the surgical osteotomy on the PBF and/or PS. METHODS: Twenty-six patients undergoing orthognathic surgery (Le Fort I or bilateral sagittal split osteotomy [BSSO]) were compared to sixteen control patients treated by fixed appliances only using Laser Doppler flowmeter (LDF) and thermal testing (CO2 snow). Surgery patients were tested at T1 (presurgery), T2 (4-5 weeks postsurgery), T3 (3 months postsurgery), and T4 (6 months postsurgery). Control patients were tested at T1 (pretreatment), T2 (6 months posttreatment), T3 (12 months posttreatment), and T4 (18 months posttreatment). Differences between the maxilla and mandible were assessed. RESULTS: No differences in PBF or PS were recorded in the control group. In the surgery group, both jaws followed the same pattern after surgery, an initial decrease at T2 followed by a gradual recovery to pretreatment PBF levels with no significant difference between T1 versus T4 in both jaws. No difference in PBF was observed between the maxilla and mandible at any testing time interval. CONCLUSIONS AND CLINICAL IMPLICATIONS: PBF and PS of the anterior dentition was severely affected immediately postsurgery, followed by a gradual increase to full recovery. This pattern of recovery was exhibited in both jaws. A negative sensibility response or discoloration should not be seen as an indication of irreversible ischemic pulp changes. Monitoring for at least 6 months or using LDF as a confirmatory test is required before any irreversible endodontic treatment is to be considered.

A Gas Flow Measurement System Based on Lead Zirconate Titanate Piezoelectric Micromachined Ultrasonic Transducer.

Ultrasonic flowmeter is one of the most widely used devices in flow measurement. Traditional bulk piezoelectric ceramic transducers restrict their application to small pipe diameters. In this paper, we propose an ultrasonic gas flowmeter based on a PZT piezoelectric micromachined ultrasonic transducer (PMUT) array. Two PMUT arrays with a resonant frequency of 125 kHz are used as the sensitive elements of the ultrasonic gas flowmeter to realize alternate transmission and reception of ultrasonic signals. The sensor contains 5 × 5 circular elements with a size of 3.7 × 3.7 mm2. An FPGA with a resolution of ns is used to process the received signal, and a flow system with overlapping acoustic paths and flow paths is designed. Compared with traditional measurement methods, the sensitivity is greatly improved. The flow system achieves high-precision measurement of gas flow in a 20 mm pipe diameter. The flow measurement range is 0.5-7 m/s and the relative error of correction is within 4%.

Pulpal blood flow changes and pain scores related to using Superelastic 0. 018-inch Nickel Titanium as the first orthodontic alignment archwire: a prospective clinical trial

Abstract Background Optimal orthodontic force results in maximum rate of tooth movement without tissue damage. Even though starting orthodontic treatment with a thicker archwire may shorten treatment duration, the evidence on the effect of using 0.018-inch NiTi as the first alignment archwire on pulpal blood flow (PBF) status is still scarce. Objectives to record PBF changes and pain scores associated with using 0.018-inch NiTi as the first alignment archwire during fixed orthodontic treatment. Methodology Patients were selected from subjects attending postgraduate orthodontic teaching clinics at Jordan University of Science and Technology. In total, forty healthy patients who exhibited mild lower arch crowding were included. A split-mouth trial design was used. Each patient received two archwire sizes at one time joined in the midline by crimpable hook and applied in the lower arch. Patients were assigned into one of two groups based on archwire sizes used. Group 1: 0.014-inch and 0.018-inch NiTi (Six males, 14 females aged 19.4±1.33 years) and Group 2: 0.016-inch and 0.018-inch NiTi (Seven males, 13 females aged 19.6±1.45 years). The archwire size group was randomly allocated with a 1:1 allocation ratio. A Laser Doppler Flowmeter was used to measure PBF at different time intervals (T0-T5). Pain scores were recorded using a visual analogue scale (VAS). A repeated measures ANOVA and a post-hoc Bonferroni comparison tests were conducted to examine differences at the different time points before and during orthodontic alignment. Results For all studied archwire sizes, PBF decreased 20 minutes after their placement. Most PBF changes occurred within 24hours and continued to decrease until 72 hours after archwire placement where the maximum reduction was reached. Eventually, normal values were reverted within 1 month. PBF changes were similar between all alignment - groups. Conclusions Initial orthodontic alignment with 0.018-inch NiTi does not cause irreversible changes to pulpal vasculature or produces higher pain scores.

Evaluation of Impact of Voiding Posture on Uroflowmetry Parameters in Men

PURPOSE: To evaluate the impact of voiding position on uroflowmetry parameters and to assess its potential clinical implications. MATERIALS AND METHODS: We conducted a prospective study from 2013 to 2015 and included men between 18 and 77 years old who were either healthy volunteers with an International Prostate Symptom Score (IPSS) ≤7 or men with benign prostate enlargement that were on alpha-blocker medication and had an IPSS <10. Participants underwent uroflowmetry and post-void residual urine (PVRU) measurements twice, once in a sitting position and once in a standing position. The participants were divided into 4 groups based on age (35 years or younger, 36 to 50 years, 51 to 60 years, and older than 60 years). RESULTS: A total of 740 men with a mean age of 40.35 years were evaluated. There was no significant difference in uroflowmetry parameters until the age of 50 years between the voiding positions. However, in those older than 50 years, PVRU volume was significantly lower in the sitting position than the standing position, whereas voiding time was significantly higher in the sitting position than the standing position. Other uroflowmetry parameters, including maximal and average urine flow rates, were non-significant. CONCLUSIONS: The voiding position plays an important role in the uroflowmetry parameters of elderly men. Voiding in the sitting position was found to be optimal for elderly men, whereas the role of the voiding position in healthy young men could not be determined. More research is needed to further study this issue.

Dynamic changes of blood flow in frontal cortex of diabetic rats / 中国药理学通报

Aim To investigate the changes of cerebral blood flow in rats with diabetic cognitive impairment by two-channel laser Doppler flowmeter,and to explore the changes of cerebral blood flow in diabetic rats with cognitive impairment and to investigate the changes of cerebral blood flow lesions and the central nervous system function changes in the study to provide pre-foundation.Methods Thirty-four male Wistar rats were randomly divided into two groups:blank control group and diabetic model group.The rats in the model group were treated with streptozotocin (STZ) 60 mg · kg-1,and the glucose oxidase method was used to determine fasting blood glucose ≥ 16.7 mmol · L-1 as the standard of the model.The Water maze was used to observe the behavioral changes of diabetic rats.Dual-channel laser doppler flowmeter was used to measure cerebral blood flow in diabetic rats with cognitive impairment.Another 34 male Wistar rats were randomly divided into two groups:control group and diabetic model group.Dual-channel laser doppler flowmeter was used to dynamically monitor cerebral blood flow on 0 d,7 d,14 d,21 d,28 d,35 d,42 d,56 d and 75 d.ELISA was applied to detect the concentration of iNOS,eNOS and ET-1 in cerebrospinal fluid.Results Morris water maze test showed that the time of the platform (latency) was significantly longer than that of the blank control group(P ＜0.05).The cerebral blood flow/100 g of diabetic rats with cognitive impairment was significantly lower than that of the control group (P ＜ O.05),and the blood flow in the model group was significantly lower than that in the model group (P ＜ 0.05).Compared with control group,iNOS and eNOS concentrations were markedly elevated,while ET-1 concentration obviously decreased.Conclusions The decrease of blood flow in the frontal cortex of diabetic rats with cognitive impairment suggests that it may be one of the factors leading to cognitive impairment in diabetes mellitus.Cerebral blood flow reduction occurs in the early stages of diabetes,followed by no significant deterioration.Cerebral blood flow may not be related to the changes of NO and ET-1,but the trend of cerebral blood flow may be related to the change of the two.

Development of multifunctional medical flowmeter / 医疗卫生装备

Objective To fulfill the precise control of the liquid flow by a multifunctional medical flowmeter. Methods The flowmeter had a separated structure, and was composed of a liquid pipeline unit and a flow control unit. The flow control unit apprehended a velocity of liquid level changes in the sterile pipeline by ultrasonic sensing technique, and regulated fluid speed by a SCM-controlled electromagnetic valve. Results The requirements for sterile environment were fulfilled by the sterile liquid pipeline, and the flow control unit realized precision control of flow rate and achieved the expected effect. Conclusion The flowmeter has simple structure, low cost, convenient operation and use, can greatly reduce the workload of the nursing staff and the possible health risks, and thus is worthy promoting practically.

Continuous flow phantom for the calibration of an ultrasonic transit-time flowmeter

INTRODUCTION: Ultrasound Transit-Time flowmeters are based on the fact that the time required for an ultrasound pulse to propagate through a given distance in a moving medium is a function of the vectorial sum of pulse propagation velocity and medium velocity. The most common application of this flowmeter in medicine is in the evaluation of blood flow in arteries and veins during heart vascular surgery. The present article describes the design, construction and evaluation of a flow phantom for transit-time flowmeters calibration. METHODS: Basically, it is a hydraulic circuit containing degassed and distilled water. In such a circuit, a constant differential water level is established between two columns that are interconnected by tubes with defined resistance, which determines a known flow rate. A basic theoretical model to estimate the system Reynolds Number and resistance was developed. RESULTS: A flow range between 4.43 ± 0.18 ml.min-1 and 106.88 ± 0.27 ml.min-1 was found to be compatible with physiological values in small vessels. The pressure range was between 0.20 ± 0.03 cmH2O and 12.53 ± 0.07 cmH2O, and the larger Reynolds Number was 1134.07. Experimental and theoretical resistance values were similar. CONCLUSION: A reproducible phantom was designed and built to be assembled with standard low-cost materials and is capable of generating adjustable and continuous flows that can be used to calibrate TTFM systems.

Working principles and application of different ultrafiltration control systems / 中国医学装备

Objective: To keep the ultrafiltration control systems running effectively, we take different maintenance methods. Methods:According to the different working principles, different ultrafiltration control systems need different ways to maintenance. Results:It is confirmed that maintenance can keep machine running in its best mode. Conclusion:Maintenance can provide the safe operation of hemodialysis machines, and ensure the medical quality.

Short-Term Effects of Ginkgo biloba Extract on Peripapillary Retinal Blood Flow in Normal Tension Glaucoma

PURPOSE: Based on the vascular theory of glaucoma pathogenesis, we wanted to evaluate the effect of Ginkgo biloba extract (GBE) on peripapillary blood flow in patients with normal tension glaucoma (NTG). METHODS: Thirty patients with NTG were randomly placed in the GBE-treated or control groups. The GBE-treated group received 80 mg GBE orally, twice a day for four weeks, and the control group received a placebo twice a day for four weeks. Complete ocular examinations including visual field, Heidelberg retina flowmeter, and systemic examinations were performed on the first study day and on the day treatment was completed. RESULTS: After GBE treatment, the mean blood flow, volume, and velocity increased at almost all points, and there was a statistically significant increase in blood flow at almost all points, in comparison to the placebo. Blood volume significantly increased only in the superior nasal and superior temporal neuroretinal rim areas. GBE also significantly increased blood velocity in areas of the inferior temporal neuroretinal rim and superior temporal peripapillary area. CONCLUSIONS: GBE administration appears to have desirable effect on ocular blood flow in NTG patients.

Short-Term Effects of Ginkgo biloba Extract on Peripapillary Retinal Blood Flow in Normal Tension Glaucoma

PURPOSE: Based on the vascular theory of glaucoma pathogenesis, we wanted to evaluate the effect of Ginkgo biloba extract (GBE) on peripapillary blood flow in patients with normal tension glaucoma (NTG). METHODS: Thirty patients with NTG were randomly placed in the GBE-treated or control groups. The GBE-treated group received 80 mg GBE orally, twice a day for four weeks, and the control group received a placebo twice a day for four weeks. Complete ocular examinations including visual field, Heidelberg retina flowmeter, and systemic examinations were performed on the first study day and on the day treatment was completed. RESULTS: After GBE treatment, the mean blood flow, volume, and velocity increased at almost all points, and there was a statistically significant increase in blood flow at almost all points, in comparison to the placebo. Blood volume significantly increased only in the superior nasal and superior temporal neuroretinal rim areas. GBE also significantly increased blood velocity in areas of the inferior temporal neuroretinal rim and superior temporal peripapillary area. CONCLUSIONS: GBE administration appears to have desirable effect on ocular blood flow in NTG patients.

Regulation of pulpal microcirculation by calcitonin gene-related peptide / 대한치과보존학회지

The purpose of this study was to investigate the function of calcitonin gene-related peptide (CGRP) in regulatory mechanism of pulpal microcirculation with the aim of elucidating neurogenic inflammation. Experiments were performed on twelve cats under general anesthesia. CGRP was administered through the femoral vein to see the systemic influence and through the external carotid artery to see the local effect. Sympathetic nerve to the dental pulp was stimulated electrically and pulpal blood flow (PBF) was measured with a laser Doppler flowmeter on the canine teeth to the drug administration. The paired variables of control and experimental data were compared by paired t-test and differences with p < 0.05 were considered statistically significant. Systemic administration of CGRP (0.3 microg/kg) exerted decreases in systemic blood pressure and caused changes in PBF with an initial increase followed by decrease and a more marked second increase and decrease. Close intra-arterial (i.a.) injection of CGRP (0.03 microg/kg) resulted in slight PBF increase. The effect of CGRP resulted in no significant increase in PBF in the presence of CGRP8-37. The electrical stimulation of the sympathetic nerve alone resulted in PBF decreases. The i.a. administration of CGRP following the electrical stimulation of the sympathetic nerve compensated the decreased PBF. Therefore, CGRP effectively blocked the sympathetic nerve stimulation-induced PBF decrease. Results of the present study have provided evidences that even though the local vasodilatory function of CGRP are weak, CGRP is effectively involved in blocking the vasoconstriction caused by sympathetic nerve stimulation in the feline dental pulp.

Measurement of Vaginal Blood Flow using Laser Doppler Flowmetry in Rabbit / 대한남성과학회지

PURPOSE: One of the problems using laser doppler flowmetry is variability in the measurements. The purposes of this study were to investigate the regional differences of vaginal blood flow using laser Doppler flowmetry and to suggest a method to enhance the accuracy of measurement. MATERIALS AND METHODS: In New Zealand White female rabbits(3.0~3.5 kg, n=10), vaginal blood flow was measured by laser doppler flowmetry using a surface probe. Flow was measured at the anterior, posterior, left, and right side of vaginal wall in each vaginal introitus and proximal 2 cm of the vaginal wall. Each site was measured 3 times separately. The data were analyzed using two-way ANOVA and repeated measures ANOVA. RESULTS: Regional vaginal blood flows(ml/min/100 gm tissue) at the anterior, posterior, left, and right vaginal wall were 19.7+/-8.7, 19.6+/-7.3, 19.3+/-7.8, 18.8+/-7.2 at vaginal introitus and 27.3+/-8.8, 18.9+/-7.5, 22.6+/-7.1, 20.8+/-5.7 at the proximal 2 cm of vaginal introitus, respectively. Differences were not statistically significant(p> 0.05), as there was a wide range of variation. CONCLUSIONS: Vaginal blood flow did not show any regional differences in the distal part of the rabbit vagina. Repeated measurements may decrease the variation of vaginal blood flow by laser Doppler flowmetry.

The Predictive Value of Laser Doppler for Flap Survival

If we could predict the necrosis of the flap caused by reperfusion injury, we can minimize the necrosis of the flap by taking appropriate action before necrosis begins. In this study, we examined whether we can predict the survival of flap under reperfusion injury or not, by measuring laser doppler flow meter values. We divided the group into the control and experimental groups corresponding to 6, 8, 9, 10, and 12hours after reperfusion(hours after ligation of auricular central artery). In each group, we examined necrotic change, perfusion unit (PU), serum superoxide dismutase (SOD), glutathione peroxidase, angiography and pathologic findings. No necrosis was observed in the 6 and 8 hours group but 8, 18, 20 hours after ligation, necrosis was observed, Also in each of 9, 10 and 12 hours group (each group consisted of 20 flaps), necrosis were noted. According to the above data, the critical time of necrosis in the auricular skin flap model lies between about 8 to 9 hours. Comparing the PU between the necrosis and non-necrosis groups, the former group showed a mean 39.57 PU increase after 60 min of reperfusion, and the latter group showed a mean increase of 21.21 PU. We can conclude that better flow can dilute oxygen free radical into systemic circulation, and this means less injuries are caused on vessels. Our study implies that if blood flow increase is less than 30 PU, intensive care is needed to save the flap. Additionally, we found significant decrease of serum SOD and glutathione peroxidase in the necrotic group. Therefore, monitoring these serum markers will be helpful in predicting reperfusion injury and supplementing these enzymes could be helpful to save the flap. The laser doppler flow meter is thought to be helpful in clinical circumstances for evaluating the circulation of the flap after the operation. However, more accumulation of clinical studies should be necessary establishing useful clinical data.

The influence of epinephrine concentration in local anesthetics on pulpal and gingival blood flows / 대한치과보존학회지

No abstract available.

Intraoperative comparison of left internal mammary artery blood flow: immediately after implantation versus before sternum closure / 中华胸心血管外科杂志

Objective: The study was to analyze hemodynamic changes of blood flow of left internal mammary artery (LIMA) in off-pump coronary bypass surgery (OPCAB). Methods: From January 2002 to August 2002, a total of 65 patients received intraoperative hemodynamic assessment of their bypass grafts by transit-time flowmeter(TTFM) during OPCAB. All operations and flow measurements were performed by the same surgeon (GCQ). The mean age of patients was (64.3?0.94) years(range 47 to 75 years), There were 50 men and 15 women. One-vessel disease was in 7 patients, two-vessel disease in 26, three-vessel disease in 32, and left main stem disease (isolated or associated) in 22. Left anterior descending artery (LAD) was routinely bypassed with LIMA. The blood flow of LIMA was measured immediately after completion of the anastomosis to LAD (early phase) and before sternum closure (late phase) using transit-time flowmeter. Results: The mean flow significantly decreased from (29.91?3.32) ml/min in early phase to (25.12?2.56) ml/min, P

Metrology Measurement and Quality Analysis of Medical Oxygen Flowmeter / 医疗卫生装备

Objective To check some medical oxygen flowmeters in use in the military area command. Methods According to JJG 917-1996 buoy oxygen inhalant measuring rules, 930 oxygen flowmeters in the military area command were measured. Results The unqualified reasons of medical oxygen flowmeter mainly lay in the capability decline of pressure resistance of humid bottle, the poor airproof of the interface, the overflow of pressure, and the overflow of flux value. Conclusion To improve the quality situation of medical oxygen flowmeter, the department of technical supervision, hospital and manufacturer need to make efforts together.

Macular Hemodynamics before and after Retinal Photocoagulation in Branch Retinal Vein Occlusion using Heidelberg Retina Flow meter(HRF )

To investigate the pathogenesis of macular edema in branch retinal vein occlusion(BRVO)and its attributing factors, we measured the macular circulation using HRF(Heidelberg Retina Flowmeter)before, 1 hour, 1 day, and 1 month after grid laser photocoagulation in 12 patients. After laser photocoagulation, the macula circulation significantly increased in 8 eyes(group 1), and remained unchanged in 4 eyes(group 2). Mean postoperative macular circulation of group 1 was blood volume 136.2%, blood flow 148.0%, and blood velocity 144.4%. And mean postoperative macular circulation of group 2 was blood volume 103.8%, blood flow 97.8%, and blood velocity 98.8%. The mean age of the patient was higher in group 1(group1:mean age 59.0, group 2:mean age 43.5, p=0.0008)and the interval between the onset of BRVO and photocoagulation was longer in group 1 than in group 2(group 1:12.4 months, group 2:4.3 months, p=0.0233). Our results suggest that retinal autoregulation may play an important role in the resolution of macular edema in BRVO after grid photocoagulation. Therefore the evaluation of retinal autoregulation using HRF is important in determining the treatment guide line and the prognosis of photocoagulation.