scholarly journals CBM Performance for Λ Hyperon Directed Flow Measurements in Au + Au Collisions at 12A GeV/c

Particles ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 288-295
Author(s):  
Oleksii Lubynets ◽  
Ilya Selyuzhenkov ◽  
Viktor Klochkov
Keyword(s):  
Transverse Momentum ◽  
Performance Studies ◽  
Flow Measurement ◽  
Azimuthal Angle ◽  
Weak Decay ◽  
Candidate Selection ◽  
Current Status ◽  
Detector Response ◽  
Directed Flow ◽  
Flow Measurements

We present the current status of the performance studies of Λ hyperon directed flow measurement with the CBM experiment at the future FAIR facility in Darmstadt. Kalman Filter mathematics is used to reconstruct Λ→pπ− weak decay kinematics, while the Particle Finder Simple package is used to optimize criteria for Λ hyperon candidate selection. Directed flow of Λ hyperons is studied as a function of rapidity, transverse momentum and collision centrality. The effects on flow measurement due to non-uniformity of the CBM detector response in the azimuthal angle, transverse momentum and rapidity are corrected using the QnTools analysis framework.

Investigation of the influence of the flow structure on the accuracy of flow measurement before a hydrometric structure in an open channel

2020 ◽  
pp. 41-44
Author(s):  
Anatoly Kusher
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Water Flow ◽  
Flow Measurement ◽  
Water Discharge ◽  
Critical Depth ◽  
Flow Measurements ◽  
Study Results ◽  
Flow Velocity Profile ◽  
Upstream Flow

The reliability of water flow measurement in irrigational canals depends on the measurement method and design features of the flow-measuring structure and the upstream flow velocity profile. The flow velocity profile is a function of the channel geometry and wall roughness. The article presents the study results of the influence of the upstream flow velocity profile on the discharge measurement accuracy. For this, the physical and numerical modeling of two structures was carried out: a critical depth flume and a hydrometric overfall in a rectangular channel. According to the data of numerical simulation of the critical depth flume with a uniform and parabolic (1/7) velocity profile in the upstream channel, the values of water discharge differ very little from the experimental values in the laboratory model with a similar geometry (δ < 2 %). In contrast to the critical depth flume, a change in the velocity profile only due to an increase in the height of the bottom roughness by 3 mm causes a decrease of the overfall discharge coefficient by 4…5 %. According to the results of the numerical and physical modeling, it was found that an increase of backwater by hydrometric structure reduces the influence of the upstream flow velocity profile and increases the reliability of water flow measurements.

Revascularization and Aneurysm Surgery: Current Status

Neurosurgery ◽  
1985 ◽  
Vol 16 (1) ◽  
pp. 111-116 ◽  
Author(s):  
Robert F. Spetzler ◽  
Philip L. Carter
Keyword(s):  
Intracranial Aneurysms ◽  
Current Status ◽  
Aneurysm Surgery ◽  
Parent Vessel ◽  
Vessel Occlusion ◽  
Flow Measurements ◽  
Stump Pressure ◽  
Blood Flow Measurements ◽  
Vessel Ligation

Abstract Unclippable intracranial aneurysms are most effectively treated by hunterian ligation; however, the attendant risk of cerebral ischemia is significant. Many techniques have been used in an attempt to predict the safety of proximal vessel occlusion. Unfortunately, there is none that is risk-free and highly successful. A combination of stump pressure and cerebral blood flow measurements has been shown to be the most accurate in the acute assessment. In addition, recent studies have demonstrated that the long term risk of carotid ligation is significant. Extracranial-intracranial bypass grafting (EC-IC) has been shown to improve the safety of parent vessel ligation and is a low risk procedure. Whenever hunterian ligation is planned for the treatment of an intracranial aneurysm, EC-IC should be strongly considered. (Neurosurgery 16:111–116, 1985)

The Accuracy of Transit Time Flow Measurement in Predicting Graft Patency after Coronary Artery Bypass Grafting

2013 ◽  
Vol 8 (6) ◽  
pp. 416-419 ◽  
Author(s):  
Patrick F. Walker ◽  
William T. Daniel ◽  
Emmanuel Moss ◽  
Vinod H. Thourani ◽  
Patrick Kilgo ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Coronary Artery Bypass Grafting ◽  
Transit Time ◽  
Pulsatility Index ◽  
Flow Measurement ◽  
Artery Bypass ◽  
Graft Patency ◽  
Bypass Grafting ◽  
Flow Measurements ◽  
Time Flow

Objective Transit time flow measurement (TTFM) is a method used to assess intraoperative blood flow after vascular anastomoses. Angiography represents the criterion standard for the assessment of graft patency after coronary artery bypass grafting (CABG). The purpose of this study was to compare flow measurements from TTFM to diagnostic angiography. Methods From October 9, 2009, to April 30, 2012, a total of 259 patients underwent robotic-assisted CABG procedures at a single institution. Of these, 160 patients had both TTFM and either intraoperative or postoperative angiography of the left internal mammary artery to the left anterior descending coronary artery graft. Transit time flow measurements were obtained after completion of the anastomosis and after administration of protamine before chest closure. Transit time flow measurement assessment included pulsatility index, diastolic fraction, and flow (milliliters per minute). Angiograms were graded according to the Fitzgibbon criteria. The patients were grouped according to angiographic findings, with perfect grafts defined as FitzGibbon A and problematic grafts defined as either Fitzgibbon B or O. Results Overall, there were 152 (95%) of 160 angiographically perfect grafts (FitzGibbon A). Of the eight problematic grafts, five were occluded (Fitzgibbon O) and three had significant flow-limiting lesions (FitzGibbon B). Two patients had intraoperative graft revision after completion angiography, one had redo CABG during the same hospitalization, and five were treated with percutaneous coronary intervention. A significant difference was seen in mean ± SD flow (34.3 ± 16.8 mL/min vs 23.9 ± 12.5 mL/min, P = 0.033) between patent and nonpatent grafts but not in pulsatility index (1.98 ± 0.76 vs 1.65 ± 0.48, P = 0.16) or diastolic fraction (73.5% ± 8.45% vs 70.9% ± 6.15%, P = 0.13). Conclusions Although TTFM can be a useful tool for graft assessment after CABG, false negatives can occur. Angiography remains the criterion standard to assess graft patency and quality of the anastomosis after CABG.

Erosive Wear of Sharp-Edged Orifice Plates

2007 ◽  
Author(s):  
L. I. Ezekoye
Keyword(s):  
Flow Measurement ◽  
Erosive Wear ◽  
Wear Test ◽  
Flow Measurements ◽  
Accident Conditions

Sharp-edged orifice plates are extensively used in flow measurement and flow trimming. In many plant applications where they are used, orifices are installed in systems which are generally clean and debris free. However, there are applications where the system may be either debris laden or exposed, in accident conditions, to debris that could challenge the effectiveness of orifices. This paper presents the results of an accelerated erosive wear test of aluminum and steel orifice plates to determine firstly, how sharp-edged orifices wear in such medium, and secondly, how the wear affects flow measurements.

Enhancement of flow measurement for graft verification

2019 ◽  
Vol 27 (8) ◽  
pp. 646-651
Author(s):  
Yury Y Vechersky ◽  
Vasily V Zatolokin ◽  
Boris N Kozlov ◽  
Aleksandra A Nenakhova ◽  
Vladimir M Shipulin
Keyword(s):  
Coronary Artery ◽  
Transit Time ◽  
Flow Measurement ◽  
Artery Bypass ◽  
Coronary Bypass ◽  
Flow Measurements ◽  
Technical Problems ◽  
Technical Errors ◽  
Time Flow ◽  
Coronary Bypass Grafts

Background We aimed to evaluate multiple transit-time flow measurements during coronary artery bypass grafting. Methods Transit-time flow measurements were performed first on the arrested heart both with and without a proximal snare on the target coronary artery, second, after weaning from cardiopulmonary bypass, and third, before chest closure. Results Among the 214 grafts considered, 9 (4.2%) were patent and 6 (2.8%) were failing. In the failed grafts, an abnormal transit-time flow was found during the first measurement, in 5 (2.3%) cases with a proximal snare and in one (0.47%) without a snare. In these cases, technical errors with the distal anastomoses were found and immediately corrected. A problem with the proximal anastomosis was found in one graft during the second measurement and corrected right away. Bending due to excessive length was found in 2 (0.93%) grafts during the third measurement, and graft repositioning was performed. The first transit-time flow measurement showed that mean graft flow was significantly decreased with a proximal snare compared to without a proximal snare, throughout the entire coronary territory. Pulsatility index during the first transit-time flow measurement was higher with a proximal snare than without one. Conclusions The 3-time transit-time flow measurement strategy makes it possible to verify and immediately correct technical problems with coronary bypass grafts.

scholarly journals A fully parametric option in the LHCb simulation framework

2019 ◽  
Vol 214 ◽  
pp. 02024
Author(s):  
Benedetto Gianluca Siddi
Keyword(s):  
Magnetic Field ◽  
Particle Transport ◽  
General Purpose ◽  
Current Status ◽  
Detector Response ◽  
Simulation Framework ◽  
Present Contribution ◽  
Detector Resolution ◽  
Modular Software ◽  
Stable Particles

Faster alternatives to a detailed, GEANT4-based simulation are being pursued within the LHCb experiment. In this context the integration of the Delphes toolkit in the LHCb simulation framework is intended to provide a fully parameterized option. Delphes is a modular software designed for general-purpose experiments such as ATLAS and CMS to quickly propagate stable particles using a parametric approach and to provide reconstructed physical objects as output. It includes propagation inside a magnetic field and parameterized response for tracking and muon systems as well as calorimeters. Particle energies are computed by smearing the initial visible particles momentaaccording to detector resolution. The present contribution illustrates the current status of the Delphes toolkit in Gauss, the LHCb simulation framework. In this integration the particle transport performed by GEANT4 and subsequent mimicking of detector response and reconstruction has been replaced with a parametric response of the various detector elements. The implementation required sig-nificant changes to Delphes itself to constrain the particle transport inside the detector acceptance and to match the LHCb dipole magnetic field. The configuration of various parametrisations of resolution and efficiency is also a major aspect of the work to provide a fully functional simulation. The output of the resulting fast simulation is formatted in such a way that can be used in the LHCb physics analysis framework.

Knowledge-based systems and operational hydrology

1991 ◽  
Vol 18 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Slobodan P. Simonovic
Keyword(s):  
Expert System ◽  
Flow Measurement ◽  
Knowledge Based Systems ◽  
Flow Measurements ◽  
Knowledge Based ◽  
Original Concept ◽  
System Water ◽  
Potential Use ◽  
Selection Of

Knowledge-based systems were brought to the attention of hydrologists almost a decade ago. The application of knowledge-based systems technology is natural and appropriate for the field of hydrology because it contains numerous procedures developed from theory, actual practice, and experience. The emphasis of the present paper is on demystifying knowledge-based systems of artificial intelligence. After a detailed review of the most important applications to the field of hydrology, the original concept for applying knowledge-based technology is presented. The discussion ends with the list of possible benefits from the application of knowledge-based technology. An expert system for the selection of a suitable method for flow measurement in open channels is used as a case study to illustrate the discussion in the paper. The system has been designed for potential use in Environment Canada. Key words: expert system, water resources, hydrology, flow measurements.

Review of Critical Flowmeters for Gas Flow Measurements

1962 ◽  
Vol 84 (4) ◽  
pp. 447-457 ◽  
Author(s):  
B. T. Arnberg
Keyword(s):  
Mass Flow ◽  
Flow Measurement ◽  
Gas Flow ◽  
Flow Measurements ◽  
Flow Rates ◽  
Real Gas ◽  
Discharge Coefficients ◽  
Critical Nozzles ◽  
Mass Flow Rates ◽  
Flow Functions

Critical flowmeters for accurately measuring the mass flow rates of nonreacting real gases were reviewed. Discussions were presented on theoretical flow functions, on parameters for correlating discharge coefficients, and on the importance of real gas properties. The performance characteristics of critical nozzles and orifices of several designs were reviewed. Approaches were discussed to problems which must be researched before the fullest potential of this type of flow measurement can be realized.

Modeling detector response in airborne gamma‐ray spectrometry

Geophysics ◽  
1999 ◽  
Vol 64 (5) ◽  
pp. 1378-1392 ◽  
Author(s):  
Stephen Billings ◽  
Jens Hovgaard
Keyword(s):  
Count Rate ◽  
Gamma Ray ◽  
Solid Angle ◽  
Azimuthal Angle ◽  
Geometrical Model ◽  
Detector Response ◽  
Gamma Ray Spectrometry ◽  
Uniform Model ◽  
Detector Model ◽  
Peak Count

A geometrical detector model of airborne gamma‐ray spectrometry is presented for data acquired using a rectangular detector of arbitrary dimensions. The detector response is modeled by calculating variations in solid angle and detector thickness for sources at different orientations. This gives the total count rate, which is then multiplied by a factor, assumed independent of orientation, to give the peak count rate. The model shows excellent agreement with experimental data collected using a 4.2-liter detector and with Monte Carlo simulations of a 16.8-liter detector. Results for the 4.2-liter crystal showed significant asymmetry. However, for a typical airborne system, with a 16.8-liter crystal, the asymmetry was weak because the detector had about the same solid angle and thickness at any azimuthal angle. The point spread function for the geometrical detector model differed significantly from a uniform detector model, the latter predicting a lower spatial resolution. This implies that surveys designed on the uniform assumption may undersample the signal between flight lines. For example, at 60 m elevation, the area that contributes 90% of the thorium signal is predicted to be 10.9 hectares (ha) for the uniform model and only 7.6 ha for the geometrical model. The model can be extended to incorporate aircraft velocity by convolving the stationary model with a rectangular function. Aircraft velocity can have a substantial influence on the modeled response if long integration times permit significant displacement of sources relative to the height of the aircraft.

scholarly journals The signature of charge dependent directed flow observables by electromagnetic fields in heavy ion collisions

2021 ◽  
Vol 136 (7) ◽  
Author(s):  
Yifeng Sun ◽  
Vincenzo Greco ◽  
Salvatore Plumari
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Fields ◽  
Complex Dynamics ◽  
Azimuthal Angle ◽  
Charged Particles ◽  
Heavy Ion ◽  
Strong Interactions ◽  
Directed Flow ◽  
The Difference ◽  
Freeze Out

AbstractWe discuss the generation of the directed flow $$v_1(p_T,y_z)$$ v 1 ( p T , y z ) induced by the electromagnetic field as a function of $$p_T$$ p T and $$y_z$$ y z . Despite the complex dynamics of charged particles due to strong interactions generating several anisotropies in the azimuthal angle, it is possible at $$p_T > m$$ p T > m to directly correlate the splitting in $$v_1$$ v 1 of heavy quarks with different charges to some main features of the magnetic field, and in particular its values at formation and freeze-out time. We further found that the slope of the splitting $$d\Delta v_1/dy_z|_{y_z=0}$$ d Δ v 1 / d y z | y z = 0 of positively and negatively charged particles at high $$p_T$$ p T can be formulated as $$d\Delta v_1/dy_z|_{y_z=0}=-\alpha \frac{\partial \ln f}{\partial p_T}+\frac{2\alpha -\beta }{p_T}$$ d Δ v 1 / d y z | y z = 0 = - α ∂ ln f ∂ p T + 2 α - β p T , where f is the $$p_T$$ p T spectra of the charged particles and the constants $$\alpha $$ α and $$\beta $$ β (order of MeV) are constrained by the y component of magnetic fields and the sign of $$\alpha $$ α is simply determined by the difference $$\Delta [tB_y(t)]$$ Δ [ t B y ( t ) ] in the center of colliding systems at the formation time of particles and at the time when particles leave the effective range of electromagnetic fields or freeze out. The formula is derived from general considerations and is confirmed by several related numerical simulations; it supplies a useful guide to quantify the effect of different magnetic field configurations and provides an evidence of why the measurement of $$\Delta v_1$$ Δ v 1 of charm, bottom and leptons from $$Z^0$$ Z 0 decay and their correlations are a powerful probe of the initial e.m. fields in ultra-relativistic collisions.

Sign in / Sign up

Export Citation Format

Share Document