Experimental Estimation of Two-Phase Flow Parameters in the Pneumatic System of a Sowing Complex

The increase of system dynamic within the area of pneumatics requires sophisticated numerical methods to determine the systems’ performance. Cycle durations in the range of just a few milliseconds and below violate the assumption of a stationary process. State of the art pneumatic calculations are built upon this assumption and, therefore, gas dynamic solvers have to be used to predict the systems’ behavior accurately. In general it is possible to calculate several flow parameters for transient gaseous flows using computational fluid dynamics (CFD) software, but despite increasing processing power of modern computers, solving particular problems is yet time-consuming. A simulation of a few milliseconds results in a computational time of several hours which makes the design of a highly dynamic pneumatic system lengthy. This paper presents a one dimensional transient numerical model which is capable of computing a transient pneumatic system’s performance time-efficiently yet retaining the accuracy of a CFD simulation. It allows to determine flow parameters, e.g., density, pressure and velocity, within transient gaseous flows including discontinuities. In particular the proposed model depicts an approach to calculate transient flows with discontinuous flow curvature. Such jumps naturally occur in pneumatic systems within hose connectors or valves. Numerical results are compared to a CFD parameter study to verify the one dimensional simulation.

A new magnetorheological (MR) damper has been designed, manufactured, modelled and tested under cyclic loads. A faulty behaviour of the damper was accidentally detected during the experiments. It was deduced that the presence of air bubbles within the MR fluid is the main reason for that failure mode of the damper. The AMT-Smartec+ MR fluid used in the current study, a new MR fluid whose characteristics are not available in the literature, exhibits good magnetic properties. However, the fluid has a very high viscosity in the absence of magnetic field. It is assumed that this high viscosity enables the retention of air bubbles in the damper and causes the faulty behaviour. To prove this assumption, a coupled numerical approach has been developed. The approach incorporates a Finite Element Analysis (FEA) of the magnetic circuit and a Computational Fluid Dynamics (CFD) analysis of the fluid flow. A similar approach was presented in a previous publication in which an ideal behaviour of an MR damper (no effect of air bubbles) was investigated. The model has been modified in the current study to include the effect of air bubbles. The results were found to support the assumptions for the reasons of the failure symptoms of the current MR damper. The results are shown in a comparative way between the former and current studies to show the differences in flow parameters, namely: pressure, velocity and viscosity, in the faultless and faulty modes. The results indicate that the presence of air bubbles in MR dampers reduces the damper force considerably. Therefore, the effect of the high yield stress of MR fluids due to the magnetic field is reduced.

Oil-water two-phase flow commonly occurs in the process of crude oil electric dehydration. Here, through dynamic changes in the water content and conductivity of oil-water two-phase flow in the process of electric dehydration, the influence of water content and conductivity on the efficiency and stability of electric dehydration is analyzed. Using real-time in-line measurements of water content and conductivity, the electric dehydration system is kept in an optimal state, which provides a basis for realizing efficient oil-water separation. Measurements of the physical parameters of oil-water two-phase flow is affected by many factors, such as the temperature of the two-phase flow, composition of the two-phase flow medium, structure of the measurement sensor, coupling of the conventional resistance–capacitance excitation signal, and processing of the measurement data. This complexity causes, some shortcomings to the control system, such as a large measurement error, limited measurement range, inability to measure the medium water phase as a conductive water phase, etc., and not meeting the requirements of the electric dehydration process. To solve that the conductivity and water content of high-conductivity crude oil emulsions cannot be measured synchronously, the RC relationship of oil-water emulsions is measured synchronously using dual-frequency digital demodulation technology, which verifies the feasibility of our test method for the synchronous measurement of physical parameters of homogeneous oil-water two-phase flow. Experimental results show that the novel measuring method (which is within the target measuring range) can be used to measure water content 0~40% and conductivity 1 ms/m~100 ms/m. The measuring error of the water content is less than 2%, and the measuring error of the conductivity is less than 5%.

IntroductionDespite spectacular visuals and the seemingly convincing rationale of using indocyanine-green-enhanced fluorescence in assessing bowel perfusion during colorectal resections, a lingering sense of subjectivity remains in the challenge of quantifying this fluorescence. This prospective study analyzed the application of O2C® spectrophotometry to quantify zones of fluorescence on the large bowel during low anterior resection.Materials and methodsPatients receiving a low anterior resection for cancer of the mid- and lower rectum were enrolled in this observational prospective study between February 2020 and December 2022. O2C® blood-flow measurement was performed at three different zones of fluorescence intensity (optimal [O], sufficient [S], and absent [A]), visualized at the designated and already skeletonized site of colon transection. The primary end point was to assess whether the O2C® flow value exceeds 164 arbitrary units (AU) at the zone of optimal fluorescence. The secondary objective was to assess whether there were statistically significant differences in flow parameters between the three zones, thus confirming reproducibility of measurements.ResultsA total of 40 patients were enrolled in this study. Of these, 38 patients remained for statistical analysis with regard to O2C® measurement of the fluorescence zones. The O2C® flow parameter measured at the zone of optimal fluorescence was greater than 164 AU in all cases (100%, p < 0.0001). There were statistically significant differences in flow parameters measured at the three different zones of fluorescence (O-S: p < 0.0001; O-A: p < 0.0001; S-A: p = 0.0023).ConclusionThis study proves the feasibility and reproducibility of quantifying zones of indocyanine green (ICG)-enhanced fluorescence on the bowel. All O2C® flow measurements that were collected at the zone of optimal fluorescence exceeded 164 AU, thereby adding more evidence to this value as a suggested cut-off parameter in terms of bowel perfusion.

3:18 PM Abstract No. 53 Changes in two-dimensional perfusion angiography before and after inferior vena cava filter retrieval

Phase distribution characteristics in 5 × 5 bowing rod bundles

The aim of this study was to investigate the acceleration potential of wave-CAIPI (controlled aliasing in parallel imaging) for 4D flow MRI, provided that image quality and precision of flow parameters are maintained. The 4D flow MRIs with acceleration factor R = 2 were performed on 10 healthy volunteers, using both wave-CAIPI and standard Cartesian/2D-CAIPI sampling for reference. In addition, 1 patient with known aortic valve stenosis was examined. The flow rate ( ), net flow ( ), peak velocity , and net average through-plane velocity ( ) were calculated in eight analysis planes in the ascending and descending aorta. The acquisitions were retrospectively undersampled (R = 6), and deviations of flow parameters and hemodynamic flow patterns were evaluated. Flow parameters measured with an undersampled wave-CAIPI trajectory showed considerably smaller deviations to the references than the 2D-CAIPI images. For , the mean absolute differences were cm/s versus cm/s; for , the mean absolute differences were ml versus ml for wave-CAIPI versus 2D-CAIPI, respectively. Noise calculations indicate that the 2D-CAIPI sampling exhibits a higher average noise level than the wave-CAIPI technique. Qualitative discrepancies in hemodynamic flow patterns, visualized through streamlines, particle traces and flow velocity vectors, could be reduced by using the undersampled wave-CAIPI trajectory. Use of wave-CAIPI instead of 2D-CAIPI sampling in retrospectively 6-fold accelerated 4D flow MRI enhances the precision of flow parameters. The acquisition time of 4D flow measurements could be reduced by a factor of 3, with minimal differences in flow parameters.

The influence of contamination on the parameters of air flow through single-hole orifice meter was investigated using computer fluid dynamics. The air flow was steady state, three-dimensional and turbulent. The main considered physical properties of air were density and dynamic viscosity. The standard k-ε turbulence model was used. Single-hole orifice meter with four different β parameters 0.5, 0.55, 0.6 and 0.7, was observed. Also, the influence of contamination formed in front of the single hole orifice meter with the same β parameters was analyzed. The pressure drop, singular pressure loss coefficient and discharge coefficient were analyzed. Two variations of the characteristics of the contamination, h=1.55 mm and r = 1.5 mm and h = 1.55 mm and r = 2.5 mm, were considered for analysis. Numerical simulations were performed using commercial software the Star CCM+. It was found that the contamination has influence on the change of pressure drop values, which directly affects the change of other parameters. The pressure drop and singular pressure loss coefficient of the orifice with contamination are smaller compared to the values for a pure orifice, whereby the measurement accuracy was reduced. Also, for cases of contamination, the discharge coefficient was increased, leading to a negative measurement error. At smaller distances of the contamination from the edge of the orifice, the percentage deviations in the values of the singular pressure loss and discharge coefficients increased.

The laws governing changes taking place in the parameters of the heterogeneous flow in a Laval nozzle were studied on the one-dimensional approximation in [1, 2]; a flow containing particles of uniform size was considered in [3–5]. In this paper we shall consider a method of calculating the parameters of a two-phase flow in the sub- and supersonic parts of an axisymmetrical Laval nozzle with due allowance for the coagulation and atomization of the particles, and shall present the results of some corresponding calculations.

Numerical and experimental study of the influence of nozzle flow parameters on yarn production by jet-ring spinning

According to the precision machining problem of the structural surface mould manufacturing process, a method for soft grits two-phase flow precision processing on the level set method (LSM) is proposed. Based on the topological structure transformation of LSM, the mechanics model of liquidliquid two phase flow in mould structuring surface precision machining was established. And the interface parameters of the abrasive two-phase flow were captured. Combining the Navier-Stokes equation, Volume of fluid Method (VOF) and SIMPLEC algorithm, the basic motion rule and related physical parameters of abrasive two-phase flow are solved. Because the simulation results of speed and pressure changes of the softness abrasive two-phase flow through 90° square bent tube are in accordance with test results of Taylor etc, which validated the effectiveness of proposed method. It contributes to the further research on softness abrasive flow precision machining.

BackgroundDiffering perfusion of the left and right ventricular coronary territory may influence flow-profiles of saphenous vein grafts (SVGs). We compared flow parameters, measured by transit-time flowmetry (TTFM), in left- and right-sided SVGs during coronary artery by-pass grafting (CABG).MethodsRoutine TTFM measurements were obtained in 167 SVGs to the left territory (55%) and 134 SVGs to the right territory (total of 301 SVGs in 207 patients). The four standard TTFM parameters, [mean graft flow (MGF), pulsatility index (PI), percentage diastolic filling (%DF), and percentage backward flow (%BF)] were compared. Differences in flow parameters were also examined according to surgical technique (on- vs. off-pump).ResultsNo significant difference between coronary territories was found for MGF, PI and %BF. However, a higher %DF was noted in left-sided SVGs in the overall cohort as well as in the on-pump (both p < 0.001) and the off-pump cohorts (p = 0.07). Further, a significantly higher %BF was found in SVGs performed off-pump to the left territory (1.2 ± 2.5 vs. 2.3 ± 3.0, p = 0.023). In a multivariate regression analysis, anastomosing a SVG to the left territory was weakly associated with higher PI (OR = 0.36, p = 0.026) and strongly associated with higher %DF (OR = 5.1, p < 0.001). No significant association was found for MGF, PI, %DF or %BF in either the on-pump nor the off-pump cohorts.ConclusionsAlthough statistically significant, the established differences in TTFM parameters between left- and right-sided vein grafts were small and unlikely to be of clinical relevance.

s S27 Eur J Echocardiography Abstracts Supplement, December 2006 251 Atrial strain (S), strain rate (SR) and diastolic function study in diabetic population without coronary artery disease C.P. Caso Pio 1 ; C.P.S. Comenale Pinto Salvatore 1 ; R.A. Ancona Roberta 1 ; D.R.M.L. De Rimini Maria Luisa 1 ; S.S. Severino Sergio 1 ; P.F. Pisacane Francesca 1 ; M.A.M. Macrino Mariangela 1 ; R.C. Calabro’ Raffaele 1 1A. O. Monaldi, Cardiology Dept., Naples, Italy Background: Abnormalities in diastolic function are considered to be an early sign of diabetic (DM) cardiomyopathy in patients without systolic ventricular dysfunction. Echocardiography with Doppler measurements of transmitral and transtricuspidal flow, together with myocardial tissue Doppler (DTI), Strain (S) and Strain rate (SR) are means to evaluate diastolic function noninvasively. Aim of study: To compare left (LV) and right (RV) ventricular systolic and diastolic function, assessed by conventional echocardiography and by DTI and atrial function assessed by S and SR, in DM patients without coronary artery disease (CAD) and non-diabetic subjects. Methods: We studied 30 subjects: 15 diabetic patients (7 M, 8 F, mean age: 54 years) without CAD, assessed by negative coronary angiography or myocardial scintigraphy and 15 controls. By Echocardiography System Seven GE equipped with TVI function we studied LV and RV systolic and diastolic function, pulmonary artery wedge pressure (PCWP), calculated by E/Ea and left and right atrial (LA/RA) peak systolic tissue S and SR in 4 and 2 chambers view, at the level of the apical segment of the septal, lateral, anterior and inferior LA walls, and RA free wall. We studied by Pulsed Doppler and DTI early (E) and late (A) diastolic wave velocity, ratio E/A, deceleration time (DT); left and right isovolumic relaxation time (IVRT) and Pulsed Doppler of pulmonary vein flow. Results: There were differences in flow parameters: DM patients had significantly higher prevalences of abnormal diastolic mitral (ratio E/A=0.83 vs 1.2) and tricuspidal (ratio E/A=0.85 vs 1.4) flow patterns than the non-diabetic patients and a significantly longer mitral valve DT (245 versus 195 msec). Although no differences were found in LA/RA diameters and volumes, the myocardial atrial S and SR were found to be significantly (p=0.002) lower for atrial septum, RA free wall and LA anterior wall in DM patients than in controls. Instead no differences were found in DM and non-diabetic patients for systolic LV function (EF=60% vs 64%), IVRT (91 vs ?90 msec), propagation velocity of transmitral flow during early ventricular filling (Vp=78.93 vs 80.12 cm/sec) and PCWP (11.87 vs 10.21 mm Hg). Conclusions: LA/RA S and SR are compromised in DM patients. Left and right diastolic function abnormalities in DM population with normal systolic function, without DM complications, hypertension and CAD, has been suggested as an earliest functional effect of a specific DM cardiomyopathy. Thus, diastolic LV and RV function in DM population are impared independently of CAD.

Since low-intensity shockwave treatment (LISWT) has putative effects on penile hemodynamics remodeling, the aim of this study was to evaluate any improvement of penile vascular flows after LISWT treatment in patients with erectile dysfunction (ED) and poor response to PDE5i. Twenty-one eugonadal patients with different ED severity underwent 6 weekly LISWT sessions (1500-4000 pulses) after 2 weeks withdrawal from PDE5i assumption. Once daily Tadalafil (2.5 mg daily) was reintroduced 4 weeks apart from LISWT termination and patients were evaluated at 1, 2 and 6 months follow-up (T1, T2, T6) by the International Index of Erectile Function-15 items questionnaire (IIEF-15) erectile function (EF) domain, Erection Hardness Score (EHS) and Global Assessment Questionnaires (GAQ). Basal Penile Color-Doppler Ultrasound parameters in the flaccid state (B-PCDU) were evaluated before, during and after interventional protocol. Mean EHS score improved in 35% of patients at T1, and in up to 50% of patients at T2 and T6 follow-up visits (P<0.05). We found 25% improvement of EF scores at T1 session, 43.75% at T2 and 62.5% at T6, respectively (P<0.05). No statistically significant differences in flow parameters, EF-domain and testosterone levels were found when baseline and last observation carried forward (LOCF) parameters were compared. The GAQ questionnaire scored higher satisfaction rates either at the end of the treatment (100%), or at LOCF (92.5%). Despite the study limitations with respect to B-PCDU in this setting, our results confirm a trend toward improvement of erectile questionnaire scores after LISWT with higher overall satisfaction rates among patients with ED. We conclude that LISWT may be an effective option in some difficult-to-treat patients with ED by improving the erectile response to PDE5i.

A bstract The elliptic and triangular flow of charged particles are measured using two-particle angular correlations in p Pb collisions in the pseudorapidity range 2.0 &lt; | η | &lt; 4.8. The data sample was collected by the LHCb experiment in 2016 at a centre-of-mass energy per nucleon pair of $$ \sqrt{s_{\textrm{NN}}}=8.16 $$ s NN = 8.16 TeV, containing in total approximately 1.5 billion collision events. Non-flow contributions are obtained in low-multiplicity collisions and subtracted to extract the flow harmonics. The results are presented as a function of event multiplicity and hadron transverse momentum. Comparisons with a full (3+1)D dynamic model indicate that it overestimates the measured elliptic flow. A comparison between the forward and backward regions reveals no significant differences in flow parameters, suggesting that final-state effects may dominate over initial-state effects in the origin of flow in small systems.