Minimum Flow Velocity Research Articles

RDII발생 및 기존 시나리오에 따른 오수간선 네트워크 설계방법 검토

In this study, the RDII impact on sewer designing in the upstream monitoring area (A site) was considered. Based on the long-term (1/1/2011~12/31/2011) rainfall and flow data consisting of 10-min interval sampling in the nearby design area (B site), the maximum RDII/DWF ratio was selected. The sewer network system at B site was evaluated by the Manning equation. Scenario 1 considering the hourly maximum flow with respect to the flow velocity showed that none of the sewer pipes satisfied the minimum flow velocity condition (0.6 m/s), and 40 pipes did not achieve half of the velocity condition. In scenario 2 considering I/I, 1 the pipes satisfied 0.6 m/s, and 35 pipes showed 0.3 m/s. Scenario 3 reflected the effect of RDII. Velocities in 26 pipes were less than 0.3 m/s, and 4 pipes satisfied the velocity condition. With respect to the allowance rate, 17 pipes were shown to have more than 99%, and none of the pipes satisfied less than 95% of the allowance rate in scenario 1. In scenario 2, 17 Ed: Per the Table pipes showed more than 99% and one pipe showed less than 95%. In scenario 3, 16 pipes showed more than 99% of the allowance rate, and 19 pipes showed less than 95%. Based on these results, it is predicted that deposition would occur due to the slow flow velocity; however, capacity would not be a problem.

Evaluation of Stability for Ecological Revetment Method with Stone Mattress and Vegetation Mound Using ANSYS Fluent

Currently, different types of revetment are installed in urban stream and various revetment methods are developed to improve the resistance to flow in order to reduce damage against flood. Especially, an eco-friendly revetment structure has a structural vulnerability against flood; however there are several theoretical and experimental technical issues to improve structural capacity. This research used computational program, ANSYS Fluent CFD, in order to evaluate the stability of ecological revetment, where stone mattress and vegetation mound are applied to protect in an extreme flood. In the result of numerical simulation, the velocity was decreased comparing to the central area of channel around the vegetation mound located at the bottom of stone mattress. The stable flow section at the downstream of stone mattress shows different according to the flow condition. If the vegetation mound is located at a section having minimum flow velocity, the erosion damage will be minimized.

Prehistorical frequency of high‐energy marine inundation events driven by typhoons in the Bay of Bangkok (Thailand), interpreted from coastal carbonate boulders

AbstractRapidly rising populations of low‐lying megacities in Asia mean that understanding the potential risk of coastal flooding by storm surge is of paramount concern. The city of Bangkok and the wider Chao Phraya River delta at the head of the Gulf of Thailand is a region topographically vulnerable to coastal flooding, but without the record of a high‐energy marine inundation (HEMI) event in historical time owing to the atypical path that a typhoon must take to be able to produce such an event.This work builds upon previous findings that identified coastal depositional evidence for HEMI events in the form of coastal carbonate boulders (CCBs) located on Ko Larn Island in the eastern Bay of Bangkok. The HEMI events were most likely driven by typhoons and the CCBs are therefore interpreted as typhoon deposits. Through uranium/thorium dating, it is revealed that from ad 1400 to ad 1600 the Bay of Bangkok possibly experienced a phase of relatively heightened storm impact. During this period, the frequency of typhoon‐driven HEMI events was approximately four events in 200 years. Waves generated onshore minimum flow velocities (MFVs) in excess of 5 m/s. Such exceptional MFVs are unlikely to be produced during the annual northeast monsoon, but are consistent with typhoon‐impacted coastlines elsewhere in the tropical Asia–Pacific region where similar CCB evidence exists. Since ad 1600, the Bay of Bangkok has enjoyed a relatively quiescent phase, recording less frequent HEMI events and of lower magnitude. However, the re‐occurrence of a typhoon‐driven HEMI event on the scale of the prehistorical events that emplaced carbonate boulders at elevation on Ko Larn Island would threaten low‐lying coasts in the Bay of Bangkok, including the Chao Phraya delta, with potentially damaging inundation. Copyright © 2015 John Wiley & Sons, Ltd.

Performance evaluation of a membraneless divergent electrode-flow-through (DEFT) alkaline electrolyser based on optimisation of electrolytic flow and electrode gap

A membraneless divergent electrode-flow-through (DEFT) alkaline electrolysis design and operating principle is investigated, which allows for the ohmic drop contribution and performance threshold limitations of a conventional membrane barrier to be overcome. Employing mesh electrodes of 30 mm diameter, operation of the electrolyser at an electrolytic flow velocity of 0.075–0.1 m s−1, resulted in an optimal electrode gap of ∼2.5 mm, while operating at greater velocities (>0.1–0.2 m s−1) allows for the employment of a smaller optimal gap of ∼0.8 mm. At an electrode gap of 2.5 mm and current densities of 3500 mA cm−2, hydrogen purity of 99.83% has been recorded. With pure nickel electrodes current densities of 101.19 mA cm−2 (at 1.80 VDC) and 326.33 mA cm−2 (at 2 VDC) have been achieved, while the use of superior catalysts, namely, RuO2/IrO2/TiO2 and Pt for the anode and cathode respectively, resulted in the current densities to increase to 219.99 mA cm−2 (at 1.8 VDC) and 474.40 mA cm−2 (at 2 VDC) at an electrode gap of 2.5 mm and a minimum flow velocity of 0.075 m s−1. The test rig is capable of generating hydrogen at a rate of 63.6 L/hr at normal temperature and pressure (NTP). The production rate follows current density linearly at high overpotentials.

Coastal vulnerability to typhoon inundation in the Bay of Bangkok, Thailand? Evidence from carbonate boulder deposits on Ko Larn island

At the head of the Gulf of Thailand, the subsiding Chao Phraya delta and adjacent low-lying coastlines surrounding the Bay of Bangkok are at risk of coastal flooding. Although a significant marine inundation event has not been experienced in historical times, this work identifies coastal depositional evidence for high-energy waves in the past. On Ko Larn island in eastern Bay of Bangkok, numerous coastal carbonate boulders (CCBs) were discovered at elevations up to 4+ m above sea level, the largest weighing over 1.3 tonnes. For the majority of CCBs, their karstified appearance bears testimony to long periods of immobility since original deposition, whilst their geomorphic settings on coastal slopes of coarse blocky talus is helpful in recognising lifting (saltation) as the probable mode of wave transport. In the absence of local tsunamigenic potential, these CCBs are considered to be prehistoric typhoon deposits, presumably sourced from fringing coral reefs by high-energy wave action. Application of existing hydrodynamic flow transport equations reveals that 4.7 m/s and 7.1 m/s are the minimum flow velocities required to transport 50% and 100% of the measured CCBs, respectively. Such values are consistent with cyclone-impacted coastlines studied elsewhere in the tropical Asia–Pacific region. Overall, the evidence of elevated carbonate boulder deposits on Ko Larn implies that typhoons before the modern record may have entered the Bay of Bangkok. The recurrence of a similar event in future would have the potential to cause damaging marine inundation on surrounding low-lying coastlines.

Tungsten oxide electrode for measurement of ultralow liquid flow velocity

This study demonstrated the application of a tungsten oxide electrode to the measurement of ultralow liquid flow velocity based on streaming potential, using a pH glass electrode and temperature sensor to compensate for changes in open circuit potential induced by pH and temperature, respectively. A change in flow velocity on the surface of the tungsten oxide electrode caused the expected shift in its open circuit potential. Experimental results showed that the open circuit potential was linear relative to the logarithmic flow velocity, and the flow sensor exhibited excellent reproducibility and a large dynamic range, with the ratio between measurable maximum and minimum flow velocity surpassing 60:1. Moreover, a higher sensitivity was observed in the alkaline solution relative to the acidic solution, indicating that the alkaline solution is more suitable for this type of measurement. In conclusion, the tungsten oxide flow sensor provides a cheap, simple, adaptable, and energy-saving solution for the measurement of ultralow liquid flow velocity.

Low-dose mannitol (0.3 g kg−1) improves the pulsatility index and minimum diastolic blood flow velocity in traumatic brain injury

Objective: The aim of the study was to investigate the effects of using low-dose mannitol (0.3 g kg−1) on the pulsatility index (PI) and minimum diastolic blood flow velocity (FV-min) of the middle cerebral artery in a traumatic brain injury (TBI).Methods: Low-dose mannitol (0.3 g kg−1) was administered to a group of 20 patients with a TBI. Transcranial Doppler (TCD) ultrasonography was used to monitor the PI and FV-min. The study included patients with a diffuse traumatic brain injury and Glasgow coma score < 8. The initial TCD ultrasonography values were pathological (PI > 1.4 and FV-min < 20 cm s−1). TCD ultrasonography examinations were carried out before mannitol administration, immediately after administration and 1, 2 and 3 hours after the administration of mannitol.Results: A one-way analysis of variance revealed significant changes in the PI (F = 8.392; p < 0.001) and FV-min (F = 8.291; p = 0.001) after the use of mannitol.Conclusions: Low-dose mannitol administration appears to be efficacious for improving the indicators of disturbed circulation in a TBI (FV-min increase, PI decrease). The maximum decrease in the PI was recorded 1 hour after the administration of mannitol and was 10.9% of the initial value. The maximum increase in the FV-min was recorded 1 hour after administration and was 29.7% of the initial value. These changes were significant ∼ 2 hours later.

Reliability Assessment of a Storm Water Drain Network

Most of the cities in India are undergoing rapid development in recent decades, and many rural localities are undergoing transformation to urban hotspots. These developments have associated land use/land cover (LULC) change that effects runoff response from catchments, which is often evident in the form of increase in runoff peaks, volume and velocity in drain networ k. Often most of the existing storm water drains are in dilapidated stage owing to improper maintenance or inadequate design. The drains are conventionally designed using procedures that are based on some anticipated future conditions. Further, values of parameters/variables associated with design of the network are traditionally considered to be deterministic. However, in reality, the parameters/variables have uncertainty due to natural and/or inherent randomness. There is a need to consider the uncertainties for designing a storm water drain network that can effectively convey the discharge. The present study evaluates performance of an existing storm water drain network in Bangalore, India, through reliability analysis by Advance First Order Second Moment (AFOSM) method. In the reliability analysis, parameters that are considered to be random variables are roughness coefficient, slope and conduit dimensions. Performance of the existing network is evaluated considering three failure modes. The first failure mode occurs when runoff exceeds capacity of the storm water drain network, while the second failure mode occurs when the actual flow velocity in the storm water drain network exceeds the maximum allowable velocity for erosion control, whereas the third failure mode occurs when the minimum flow velocity is less than the minimum allowable velocity for deposition control. In the analysis, runoff generated from subcatchments of the study area and flow velocity in storm water drains are estimated using Storm Water Management Model (SWMM). Results from the study are presented and discussed. The reliability values are low under the three failure modes, indicating a need to redesign several of the conduits to improve their reliability. This study finds use in devising plans for expansion of the Bangalore storm water drain system.

Doppler Ultrasonographic Estimation of Renal Resistive Index in Horse: Comparison Between Left and Right Kidneys

The renal resistive index (RI) is the ratio of the difference between maximum and minimum (end diastolic) flow velocity derived from the Doppler spectrum of intrarenal (segmental/interlobar) arteries. It is a good indicator for acute renal disease, acute tubular necrosis, and renal obstruction. To our knowledge, no reports are available about the values of renal RI in unsedated horses. The aim of this study was to establish a normal reference range (mean ± standard error) and to assess the reliability of the renal RI obtained using transabdominal ultrasonography in unsedated healthy horses. Thirteen conscious Thoroughbred horses judged healthy based on physical examination, complete blood count, biochemical profile, urinalysis, and ultrasonography were included. The peak-systolic and end-diastolic velocities of interlobar and arcuate arteries were measured. Intrarenal arteries were scanned by pulsed Doppler ultrasonography to calculate RI. The comparison of left versus right kidneys was analyzed with analysis of covariance (ANCOVA) procedure. Significant differences (P < .05) for the RI values were observed between left and right kidneys in the geldings (left 0.50 vs. right 0.56) and mares (left 0.50 vs. right 0.57) and were observed between left and right kidneys in trained (left 0.52 vs. right 0.55) and untrained horses (left 0.48 vs. right 0.58). The renal RI has not been modified by sex.

A modified critical velocity for road tunnel fire smoke management with dedicated smoke extraction configuration

Life safety is one of the objectives of fire engineering design for road tunnels. Fire engineering design requires maintaining a tenable condition for a period of time to allow occupants to evacuate to safety. This will be achieved by controlling the smoke under credible design fire scenarios in a tunnel. The critical location in a tunnel fire emergency condition is the tunnel region upstream of the fire, where occupants are most likely to reside as traffic jam can usually be created by the fire incident. Tenability for the downstream region of fire is not the main focus of this research because vehicles can generally drive out of the tunnel at a higher speed than that of the smoke flow, and local damper smoke extraction can help keep a tenable condition in the downstream region beyond the local fire zone, in case there is a congestion in the downstream region of the fire.To maintain a tenable condition in the upstream tunnel region from the fire incident, the required minimum longitudinal flow velocity to prevent smoke backlayering can be calculated based on NFPA 502 recommendations. This critical velocity takes no credit of the smoke extraction or active overhead fixed fire suppression effects.Smoke extraction with a dedicated smoke duct along the entire length of the tunnel is gaining popularity because of its efficiency and robustness in providing a tenable environment in the tunnel with unknown upstream and downstream traffic conditions. In this paper, a modified critical velocity to control smoke back-layering while smoke extraction and fire suppression systems are operating has been analyzed. This modified critical velocity is approximately 20% lower than the critical velocity that is recommended in NFPA 502. This allows significant savings on ventilation capacity for road tunnels which have a local smoke exhaust capability using a dedicated smoke duct.It is concluded that the smoke extraction performance is similar whether using ceiling dampers or vertical wall-mounted dampers for smoke capture to maintain tunnel tenability. However, tunnel gradients play a major role on the modified critical velocity for a nominated design fire and the required smoke extraction rate.

Performance analysis of the airfoil-slat arrangements for hydro and wind turbine applications

Standard airfoils historically used for wind and hydrokinetic turbines had maximum lift coefficients of around 1.3 at stall angles of attack, which is about 12°. At these conditions, the minimum flow velocities to generate electric power were about 7 m/s and 2 m/s for the wind turbine and the hydrokinetic turbine cases, respectively. In this study, NACA4412-NACA6411 slat–airfoil arrangement was chosen for these two cases in order to investigate the potential performance improvements. Aerodynamic performances of these cases were both numerically and experimentally investigated. The 2D and 3D numerical analysis software were used and the optimum geometric and flow conditions leading to the maximum power coefficient or the maximum lift to drag ratio were obtained. The maximum lift to drag ratio of 24.16 was obtained at the optimum geometric and flow parameters. The maximum power coefficient of 0.506 and the maximum torque were determined at the tip speed ratios of 5.5 and 4.0 respectively. The experimental work conducted in a towing tank gave the power coefficient to be 0.47 which is about %7 lower than the numerical results obtained. Hence, there is reasonable agreement between numerical end experimental values. It may be concluded that slat-hydrofoil or airfoil arrangements may be applied in the design of wind and hydrokinetic turbines for electrical power generation in lower wind velocities (3–4 m/s) and current velocities (about 1 m/s).

A device to achieve low Reynolds numbers in an open surface water channel

When investigating flow structures, and espe- cially flow transitions, research projects often seek to increase insight using complementary numerical and physical experiments. Obtaining exact Reynolds number correspondence can frequently be difficult in experiments, particularly when relatively low values are required. Often, available test facilities were designed and optimised for a specific velocity range, meaning they have restrictions on the minimum flow velocity. This study describes a device to reduce the flow velocity locally in an open surface water channel. The underlying idea is to divert a controlled fraction of the incoming flow from the working section by increasing the pressure there, resulting in reduced velocity. This idea is realised using a ‘sub-channel’ that can be inserted into the main test chamber, with a variable porosity perforated screen at its downstream end. This study assesses and optimises the flow quality inside this structure, such as usable test section length, uniformity of the velocity profiles and turbulence intensity. The results demonstrate that the device creates high quality low Reynolds number flows, which is exemplified with the canonical circular cylinder in cross-flow.

Evaluation of Plant Growth with Aerated Irrigation Water Using Venturi Pipe Part

A venturi pipe part (VPP) allows air bubbles to be inserted into flowing water from air inlet holes and so increases dissolved oxygen (DO) levels in irrigation water. The DO helps the roots absorb nutrients at a faster rate, and can increase a plant’s growth rate by up to 30 %. Therefore, the aim of this paper is to evaluate design considerations and experimental results related to characteristics of VPP in air vacuum and aeration process. Optimal flow velocity in venturi inlet is determined between 1 and 4 m/s for aeration process. For starting of air vacuum process, minimum flow velocity is determined as 0.80 m/s. The ratio of the throat diameter of VPP to the inlet diameter of VPP equals to 0.5. Also, the ratio of the air vent diameter of VPP to the throat diameter of VPP equals to 0.3. Volumetric air flowrate decreases with increasing pipe length. In addition, the effect of aerated water on plant growth is tested with a case study. The case study is carried out on growth of the onion (Allium cepa) samples. In result of this test, aerated water is capable for plant growth of the onion (A. cepa) samples. However, it increased the plant’s growth rate by 27 %. Thus, irrigation projects can be planned with both VPP (AirJection Irrigation) and subsurface drip irrigation systems.

Hydrodynamics performance of hydrofoil-slat arrangements in 3D analysis

Standard airfoils historically used for wind and hydrokinetic turbines have the maximum lift coefficients of about 1.3 at the stall angle of attack, which is about 12°. At these conditions, the minimum flow velocities to generate electric power are about 7m/s and 3m/s for wind turbine and hydrokinetic turbine, respectively. The design optimization of the rotor is very important to maximize the power production. The performance of the rotor can be determined by various geometric and flow parameters. Using leading edge slat delays the stall up to an angle of attack with a maximum lift coefficient. Three dimensional analyses were conducted on the hydrofoil-slat arrangements, NACA2415–NACA22 and NACA4412–NACA6411, the range of the tip speed ratio from 3 to 7. For the first and second arrangements, the maximum efficiency of 0.45 and 0.501 were obtained at the tip speed ratio of 5.5. For these two arrangements, the efficiencies have the values about more than 0.4 over a relatively narrow and large range of the tip speed ratio respectively. The selection of the hydrofoil (or airfoil)-slat arrangements has important effect on the performance of the system. Thus, the hydrofoil (or airfoil)-slat arrangements can be applied in the design of wind and hydrokinetic turbines in lower wind and current velocities.

Effects of Qigong Exercise on Upper Limb Lymphedema and Blood Flow in Survivors of Breast Cancer

Qigong exercise is a popular method for relieving the side effects of conventional cancer treatments in survivors of breast cancer, yet its effects are not empirically assessed. This study aimed to investigate the effects of qigong exercise on upper limb lymphedema, arterial resistance, and blood flow velocity in survivors with breast cancer and mastectomy. This study was conducted as a prospective clinical trial. Eleven survivors of breast cancer with qigong experience (mean age = 58.3 ± 10.1 years) were assigned to the experimental group and 12 survivors of breast cancer without qigong experience (mean age = 53.8 ± 4.2 years) were assigned to the control group. They all had breast cancer-related lymphedema. All procedures were completed within one session. After baseline measurements were taken, the experimental group performed 18 Forms Tai Chi Internal Qigong for approximately 6 minutes while the control group rested for similar duration in a sitting position. Both groups were then reassessed. All participants were measured on their affected upper limb circumference (by using tape measures), peripheral arterial resistance, and blood flow velocities (using a Doppler ultrasound machine). The between-group differences were not significant for all outcome measures at baseline (P > .05). The circumferences of the affected upper arm, elbow, forearm and wrist decreased after qigong exercise (P < .05). However, no significant difference was found in the circumference measures between the 2 groups posttest (P > .0125). In terms of vascular outcomes, the resistance index decreased and the maximum systolic arterial blood flow velocity (SV) and minimum diastolic arterial blood flow velocity (DV) increased significantly after qigong exercise (P < .05). The between-group difference was close to significant for SV (P = .018) and was significant for DV (P < .001) posttest. Qigong exercise could reduce conventional cancer therapy side effects such as upper limb lymphedema and poor circulatory status in survivors of breast cancer. However, such effects may be temporary, and further studies must be conducted to explore longer term effects.

Ultrasonography and Duplex Doppler Ultrasonography Based Indices in Nodular Thyroid Disease

Background. Fine needle aspiration biopsy (FNAB) is an important tool in the diagnosis of thyroid nodules. Aim. Our aim was to investigate the malignancy criteria in thyroid nodules by gray-scale ultrasonography (US) and duplex Doppler ultrasonography (DDUS), and their usefulness in reducing the number of unnecessary FNAB’s. Study design. This was a prospective observational study. Subjects and methods. 181 benign and 18 malignant thyroid nodules were evaluated by US and DDUS before FNAB or thyroidectomy. US was used to note size, shape, internal structure, nodule echogenicity, marginal properties, peripheral hypoechogenic halo, and microcalcifications. DDUS studies were used to evaluate the maximum and minimum flow velocity (V max and V min ), systolic/diastolic flow velocity ratio (S/D), pulsatility index (PI), resistive index (RI), acceleration time (AT) and acceleration value. Results. Contour irregularity, size and presence of microcalcifications (p<0.001, p=0.02 and p=0.002, respectively) and S/D, V min , PI, RI and AT were significantly different (p=0.004, p=0.007, p=0.032, p=0.003 and p=0.003, respectively) were significant for malignant nodules. Benign and malignant nodules with or without suspicious US findings had similar DDUS findings. V max , V min , PI, RI, and AT were significantly different in the presence of microcalcification (p=0.043, p=0.001, p=0.031, p=0.04, and p=0.019 respectively). AT was significantly different in the case of absence of microcalcification (p=0.019). Comparing the irregular margins, V min , PI and RI were significantly different (p=0.014, p=0.003, and p=0.014 respectively). Conclusion. Benign and malignant thyroid nodules can be differentiated using gray-scale US findings and DDUS based indices together to reduce the number of unnecessary FNAB’s.

Abnormal splenic artery diameter/hepatic artery diameter ratio in cirrhosis-induced portal hypertension

To determine an optimal cutoff value for abnormal splenic artery diameter/proper hepatic artery diameter (S/P) ratio in cirrhosis-induced portal hypertension. Patients with cirrhosis and portal hypertension (n = 770) and healthy volunteers (n = 31) underwent volumetric computed tomography three-dimensional vascular reconstruction to measure the internal diameters of the splenic artery and proper hepatic artery to calculate the S/P ratio. The cutoff value for abnormal S/P ratio was determined using receiver operating characteristic curve analysis, and the prevalence of abnormal S/P ratio and associations between abnormal S/P ratio and major complications of portal hypertension were studied using logistic regression. The receiver operating characteristic analysis showed that the cutoff points for abnormal splenic artery internal diameter and S/P ratio were > 5.19 mm and > 1.40, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value were 74.2%, 45.2%, 97.1%, and 6.6%, respectively. The prevalence of an abnormal S/P ratio in the patients with cirrhosis and portal hypertension was 83.4%. Patients with a higher S/P ratio had a lower risk of developing ascites [odds ratio (OR) = 0.708, 95%CI: 0.508-0.986, P = 0.041] and a higher risk of developing esophageal and gastric varices (OR = 1.483, 95%CI: 1.010-2.175, P = 0.044) and forming collateral circulation (OR = 1.518, 95%CI: 1.033-2.230, P = 0.034). After splenectomy, the portal venous pressure and maximum and mean portal venous flow velocities were reduced, while the flow rate and maximum and minimum flow velocities of the hepatic artery were increased (P < 0.05). The prevalence of an abnormal S/P ratio is high in patients with cirrhosis and portal hypertension, and it can be used as an important marker of splanchnic hemodynamic disturbances.

The Finite Element Analysis of Flow Field and Temperature Field in the Molten Pool of Surface Treatment by Electron Beam

A finite element model was established to describe the flow field and temperature field during the surface modification by electron beam in this paper. The driving forces of molten pool were considered in the mode. The flow of liquid metal was different between the inside and outside of the beam spot; the direction of the flow was along the surface to the specimen thickness. When the liquid metal was in the bottom of the pool, it flowed along the bottom to the pool edge. The largest flow velocity was 0.28m/s in the center of the beam spot, the minimum flow velocity was 0.11 m/s in the bottom of molten pool. The temperature of sample is uniform distribution, the temperature distribution show a gradient distribution in cross section.

B-mode and colour Doppler ultrasonography of the milk vein and musculophrenic vein in eight cows during lactation

Eight cows underwent Doppler sonographic examinations of the milk vein and musculophrenic vein from 9days prepartum to 300days postpartum. A 7.5-MHz linear transducer was used to determine the inner diameter of the veins and blood flow velocities and volumes on the left side in standing, non-sedated animals. Cows were weighed and milk yield measured at all examination times. The milk vein appeared as a vessel with an inner diameter of 2.01–2.30cm immediately beneath the skin. The maximum blood flow velocity ranged from 23.84 to 35.76cm/s before parturition, increased markedly on the day of calving (day 0), peaked at 61.14cm/s on day 1 and slowly decreased to 23.84cm/s by day 300. The profiles of the minimum and mean maximum flow velocities and flow volume were similar. The musculophrenic vein had an inner diameter of 0.76–1.07cm and its distance from the surface of the skin was 1.15–1.31cm. The profiles of the blood flow variables were irregular and did not resemble those of the milk vein. The maximum blood flow velocity ranged from 87.35 to 114.41cm/s, the minimum velocity from 5.47 to 7.60cm/s, the mean maximum velocity from 48.55 to 78.74cm/s and the blood flow volume from 1.02 to 2.44l/min. The milk vein had a larger diameter (2.16 versus 0.90cm; P<0.01), smaller maximum, minimum and mean maximum blood flow velocities (P<0.01) and a larger blood flow volume than the musculophrenic vein (P<0.01).

Evaluation of the relationship between salivation ability and blood flow velocity in the submandibular gland using pulsed Doppler ultrasonography

To investigate the possibility of predicting salivation ability using pulsed Doppler ultrasonography. Thirty healthy volunteers were enrolled in this study. The blood flow velocity in the submandibular gland before and during acid stimulation was recorded by pulsed Doppler ultrasonography. The changes in the maximum blood flow velocity (V max) and minimum blood flow velocity (V min) were analyzed and compared with the salivation abilities. Strong linear correlations between before and during acid stimulation were observed in the amount of salivation (R = 0.879, p < 0.05) and the V max (R = 0.938, p < 0.05). The mean change rate in the stimulated V max was 1.58 (range 1.10–4.58), and the mean (range) change rates in the V max after 1, 3, and 5 min of acid stimulation were 0.96 (0.47–1.47), 0.97 (0.79–1.40), and 0.98 (0.70–1.23), respectively. No strong linear correlation was observed between the amount of salivation and the blood flow velocity. Although it is known that an increase in the amount of salivation is closely related to an increase in the blood flow velocity in the salivary glands, our findings did not show a linear correlation between the amount of salivation and the blood flow velocity.