scholarly journals Flow Characteristics over Forward Facing Step and Control of Separated Flow.

1999 ◽  
Vol 65 (637) ◽  
pp. 3008-3014 ◽  
Author(s):  
Toshihiko SHAKOUCHI ◽  
Toshitake ANDO ◽  
Koji NAKANO
Keyword(s):  
Flow Characteristics ◽  
Separated Flow ◽  
Forward Facing Step ◽  
And Control

scholarly journals Frequent users of emergency departments and patient flow in Alberta and Ontario, Canada: an administrative data study

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Anqi Chen ◽  
Scott Fielding ◽  
X. Joan Hu ◽  
Patrick McLane ◽  
Andrew McRae ◽  
...  
Keyword(s):  
Length Of Stay ◽  
Emergency Departments ◽  
Patient Flow ◽  
Flow Characteristics ◽  
Initial Assessment ◽  
Cox Models ◽  
Lengths Of Stay ◽  
Random Samples ◽  
High System ◽  
And Control

Abstract Background This paper describes and compares patient flow characteristics of adult high system users (HSUs) and control groups in Alberta and Ontario emergency departments (EDs), Canada. Methods Annual cohorts of HSUs were created by identifying patients who made up the top 10% of ED users (by count of ED presentations) in the National Ambulatory Care Reporting System during 2011–2016. Random samples of patients not in the HSU groups were selected as controls. Presentation (e.g., acuity) and ED times (e.g., time to physician initial assessment [PIA], length of stay) data were extracted and described. The length of stay for 2015/2016 data was decomposed into stages and Cox models compared time between stages. Results There were 20,343,230 and 18,222,969 ED presentations made by 7,032,655 and 1,923,462 individuals in the control and HSU groups, respectively. The Ontario groups had higher acuity than the Alberta groups: about 20% in the Ontario groups were from the emergent level whereas Alberta had 11–15%. Time to PIA was similar across provinces and groups (medians of 60 min to 67 min). Lengths of stay were longest for Ontario HSUs (median = 3 h) and shortest for Alberta HSUs (median = 2.2 h). HSUs had shorter times to PIA (hazard ratio [HR] = 1.03; 95% confidence interval [CI] 1.02,1.03), longer times from PIA to decision (HR = 0.84; 95%CI 0.84,0.84), and longer times from decision to leaving the ED (HR = 0.91; 95%CI 0.91,0.91). Conclusions Ontario HSUs had higher acuity and longer ED lengths of stay than the other groups. In both provinces, HSU had shorter times to PIA and longer times after assessment.

Two-Phase Flow Through Square and Circular Microchannels—Effects of Channel Geometry

2004 ◽  
Vol 126 (4) ◽  
pp. 546-552 ◽  
Author(s):  
Peter M.-Y. Chung ◽  
Masahiro Kawaji ◽  
Akimaro Kawahara ◽  
Yuichi Shibata
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Separated Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Channel Geometry ◽  
Frictional Pressure Drop ◽  
Channel Shape

An adiabatic experiment was conducted to investigate the effect of channel geometry on gas-liquid two-phase flow characteristics in horizontal microchannels. A water-nitrogen gas mixture was pumped through a 96 μm square microchannel and the resulting flow pattern, void fraction and frictional pressure drop data were compared with those previously reported by the authors for a 100 μm circular microchannel. The pressure drop data were best estimated using a separated-flow model and the void fraction increased non-linearly with volumetric quality, regardless of the channel shape. However, the flow maps exhibited transition boundaries that were shifted depending on the channel shape.

Detailed Dynamic Modelling of an Integrated Hydraulic Actuator

2020 ◽  
Author(s):  
Dom Wilson ◽  
Ioannis Georgilas ◽  
Andrew Plummer ◽  
Pejman Iravani ◽  
Dhinesh Sangiah
Keyword(s):  
High Performance ◽  
Dynamic Modelling ◽  
Flow Characteristics ◽  
Hydraulic Cylinder ◽  
Theoretical Development ◽  
Hydraulic Actuator ◽  
Pressure Losses ◽  
Low Leakage ◽  
Smart Actuator ◽  
And Control

Abstract Hydraulic servos are characterised by their high-performance nature but due to their size and weight are not suitable for robotics where new legged applications require high power density and excellent dynamic behaviour in a small size. As an answer to this need a new class of integrated smart actuators is being developed. These systems consist of a servo valve, hydraulic cylinder, sensors and a controller all in a single device. This paper outlines the detailed modelling of the smart actuator for use in simulation and control design. The result is a model consisting of the dynamics of the novel ultra-low leakage servovalve, the valve flow characteristics considering the properties of each spool land, the single-ended cylinder with friction and the pressure losses in the supply and return lines to the actuator. The models are a combination of empirical and theoretical development, validated with experimental data. The smart actuator’s unique properties; compactness, weight and efficiency, combined with high-performance hydraulics make it well suited to mobile robot applications.

K-1328 Separated Flow and Its Control from Forward-Facing Step : Drag Reduction of Abrupt Contraction Pipe

2001 ◽  
Vol II.01.1 (0) ◽  
pp. 167-168
Author(s):  
Toshihiko Shakouchi ◽  
Toshitake Ando ◽  
Keigo Miyata ◽  
Masahide Kinoshita
Keyword(s):  
Drag Reduction ◽  
Separated Flow ◽  
Abrupt Contraction ◽  
Forward Facing Step

Study of Flow Characteristics and Control Circuit on High-Speed Solenoid Valve

2012 ◽  
Vol 619 ◽  
pp. 107-110 ◽  
Author(s):  
Wen Hua Li ◽  
Wen Lin Shao
Keyword(s):  
High Speed ◽  
Flow Characteristics ◽  
Pulse Signal ◽  
Solenoid Valve ◽  
Control Circuit ◽  
Duty Ratio ◽  
Time Sharing ◽  
Small Current ◽  
Wide Range ◽  
And Control

Through the analysis of the flow characteristics of the high-speed solenoid valve, the conclusions that the PWM signal duty ratio is the main factor affecting the solenoid valve flow is obtained, a new available any PWM pulse signal and control circuit are proposed. Further, circuit schematic is simulated by means of SIMULINK tools in MATLAB environment and Verify its stability. A time-sharing drive circuit is design based on the PWM drive mode. The driver circuit have function which is high-current open, small current maintain. Open current and maintain current of Solenoid valve can be adjusted through this circuit. Therefore, the circuit can adapt to different parameters of the solenoid valve. A wide range of applications.

Model and Calibration of a Diesel Engine Air Path With an Asymmetric Twin Scroll Turbine

2013 ◽  
Author(s):  
Mike J. Hand ◽  
Erik Hellström ◽  
Doohyun Kim ◽  
Anna Stefanopoulou ◽  
Justin Kollien ◽  
...  
Keyword(s):  
Diesel Engine ◽  
System Analysis ◽  
Flow Characteristics ◽  
Load Condition ◽  
Mean Value ◽  
Complex Flow ◽  
Transient Control ◽  
Mean Value Model ◽  
Value Model ◽  
And Control

A control-oriented model and its associated tuning methodology is presented for the air path of a six cylinder 13 L diesel engine equipped with an asymmetric twin-scroll turbine, wastegate (WG), and exhaust gas recirculation (EGR). This model is validated against experimental engine data and shows good agreement. The small scroll of the asymmetric twin scroll turbine is fed by the exhaust of three cylinders via a split manifold that operates at higher pressure than the exhaust manifold feeding the larger turbine scroll. The asymmetric design with the high exhaust back pressure on three of the six cylinders gives the necessary EGR capability, with reduced pumping work, but leads to complex flow characteristics. The mean-value model describes the flows through the engine, the flow through the two turbine scrolls, the EGR flow, and the WG flow as they are defined, and defines the pressure of the manifolds they connect to. Using seven states that capture the dynamics of the pressure and composition in the manifolds and the speed of the turbo shaft, the model can be used for transient control, along with set point optimization for the EGR and WG flows for each speed and load condition. The relatively low order of the model makes it amenable to fast simulations, system analysis, and control design.

Modeling and Control of Proportional Valve with Synchronous Motor

2015 ◽  
Vol 220-221 ◽  
pp. 457-462 ◽  
Author(s):  
Andrzej Milecki ◽  
Dominik Rybarczyk
Keyword(s):  
Permanent Magnets ◽  
Dead Zone ◽  
Flow Characteristics ◽  
Synchronous Motor ◽  
Hydraulic Actuator ◽  
Servo Drive ◽  
Proportional Valve ◽  
Modeling And Control ◽  
Basic Characteristics ◽  
And Control

The paper describes the research results of modeling and control of proportional valve with synchronous motor type PMSM (Permanent Magnets Synchronous Motor). In the paper, a simulation model of the proposed valve was developed and described. The model included the square root flow characteristics, nonlinearity of the hydraulic actuator, valve dead zone and saturation of the flow. The study included the investigations of the basic characteristics, such as valve flow characteristic and step responses. In order to determine the basic parameters of the valve, the test stand was built, on which the new valve and the servo drive with this valve were tested. A servo drive control system was based on PLC with touch panel and inverter module. In the paper, the chosen investigations results of the valve and the servo drive system are presented and shortly discussed.

An Analytical and Empirical Basis for the Design of Turbulence Amplifiers: Part I: Analysis and Experimental Confirmation

1973 ◽  
Vol 95 (2) ◽  
pp. 133-140
Author(s):  
A. C. Bell
Keyword(s):  
Flow Characteristics ◽  
Design Procedure ◽  
Rational Basis ◽  
Operating Characteristics ◽  
Empirical Relationships ◽  
Stability And Control ◽  
Jet Stability ◽  
Rational Procedure ◽  
Pressure Part ◽  
And Control

The design of turbulence amplifiers is given a rational basis by identifying the critical parameter groups necessary to completely specify the performance of a given element, deriving by analysis or experiment the relationships between these nondimensional parameter groups, and developing a rational procedure for obtaining a quantitative dimensioned set of operating characteristics from these relationships. Part I of this paper outlines the problem, identifies the required relations, and presents analyses confirmed by data. These analyses develop relationships for tube pressure-flow characteristics, jet attenuation, and recovered pressure. Part II presents empirical relationships specifying jet stability and control characteristics, and develops a design procedure with an example.

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