A Dynamic Model of a Locomotive Diesel Engine and Electrohydraulic Governor

1988 ◽  
Vol 110 (3) ◽  
pp. 405-414 ◽  
Author(s):  
C. I. Rackmil ◽  
P. N. Blumberg ◽  
D. A. Becker ◽  
R. R. Schuller ◽  
D. C. Garvey
Keyword(s):  
Steady State ◽  
Diesel Engine ◽  
Rate Of Change ◽  
Regression Equations ◽  
Detailed Model ◽  
Engine Simulation ◽  
System A ◽  
Load Demand ◽  
The Difference ◽  
Exhaust Energy

As part of a comprehensive simulation of a prototype locomotive propulsion system, a detailed model has been developed that predicts the dynamic response of an experimental two-stroke, turbocharged and intercooled diesel engine. Engine fueling and brake torque are computed from regression equations derived from an extensive data base. Corrections are applied to the calculated steady-state torque to account for dynamic deviations of in-cylinder trapped air-fuel ratio from the steady-state value. The engine simulation accurately represents the operation of the turbocharger, which is gear-driven at low turbocharger speeds, and freewheels through an overrunning clutch when exhaust energy accelerates the turbocharger beyond its geared speed. Engine fueling level, i.e., rack, is determined from a dynamic simulation of an electrohydraulic governor, which responds to the difference between the desired and the actual engine speeds. The governor representation includes: (1) finite rate of change of engine set speed; (2) load regulator feedback for control of applied engine loads; and (3) fuel limiting under conditions of excessively high load demand. The fundamentals of the engine/governor model are given in the paper along with examples that emphasize the dynamic operation of these particular components.

scholarly journals A Study on the Effects of Model Structure and Demand Allocation on Water Network Modeling

2020 ◽  
Vol 42 (3) ◽  
pp. 110-120
Author(s):  
Seonghan Kim ◽  
Kwansue Jung ◽  
Sukmin Yoon ◽  
No-Suk Park
Keyword(s):  
Steady State ◽  
Network Modeling ◽  
Extended Period ◽  
Model Structure ◽  
Water Network ◽  
Detailed Model ◽  
Water Head ◽  
Models Comparison ◽  
The Difference ◽  
Steady State Simulation

Objectives:In order to reduce the uncertainty of the pipe network modeling, the model structure was basically included all distribution pipes and several models were proposed according to the location of the water meters.Methods:For models verification, first, a steady state simulation of each model was made by constructing a model including all water supply pipes (All-meters Model), which are the bases of 3 simplified models, and considering the location of all water meters. The network analysis was performed by dividing into the steady state and the extended period simulation.Results and Discussion:From the results of models comparison, ‘All-meters Model’ and ‘All-connections Model’ were found to obtain more accurate results for constructing a water network model for simulation of water quality events in distribution network. When constructing an ‘All-meters Model’ in all networks, the model becomes complicated and data management does difficult. Therefore this study suggests a hybrid model construction.Conclusions:It would be reasonable to construct a detailed model (All-meters or All-connections Model) in looped network in which the water flow path can be changed according to the difference of water head, and a skeletonized model (Street-meters aggregation or Reduced-meters Model) for a branch network that does not have a significant impact on demand allocations.

The Rate of Change of Mouth Occlusion Pressure during Exercise

1979 ◽  
Vol 56 (5) ◽  
pp. 455-461 ◽  
Author(s):  
N. Siafakas ◽  
A. J. R. Morris ◽  
F. J. Prime
Keyword(s):  
Steady State ◽  
Linear Relationship ◽  
Regression Line ◽  
Constant Load ◽  
Rate Of Change ◽  
Significant Linear Relationship ◽  
Progressive Exercise ◽  
The Difference ◽  
Mouth Occlusion Pressure ◽  
The Relationship

1. The initial rate of change of pressure at the mouth (dP/dt) during a brief occlusion of the airways at the beginning of inspiration has been estimated in nine healthy subjects at rest, during exercise and during the first 2 min of recovery. Exercise was carried out with progressively increasing loads to the maximum tolerated (progressive exercise) and also for a period of 6 min at a constant load of 60% of the maximum (steady-state exercise). 2. A highly significant linear relationship was found between work loads and dP/dt during progressive exercise in all our subjects. 3. A highly significant linear relationship was found between ventilation and dP/dt in both forms of exercise, but the slope of the regression line was steeper during progressive than during steady-state exercise in six out of nine subjects. 4. The pattern of breathing (VT, f, VT/Tinsp., Tinsp./Ttot.) did not account for the difference in the relationship between dP/dt and ventilation during the two forms of exercise. 5. These results are in agreement with the hypothesis that dP/dt is an index of central inspiratory drive.

scholarly journals MATHEMATICAL MODELING OF INFLUENCE THE OPERATION MODE DIESEL ENGINE ON THE CONTENT OF PARTICULATE MATTER IN EXHAUST GASES

2020 ◽  
Vol 3 (156) ◽  
pp. 62-68
Author(s):  
A. Polivyanchuk
Keyword(s):  
Mathematical Modeling ◽  
Particulate Matter ◽  
Steady State ◽  
Diesel Engine ◽  
Operation Mode ◽  
Gravimetric Method ◽  
Rate Of Change ◽  
Exhaust Gases ◽  
Operating Modes ◽  
Concentration Test

The work is devoted to solving an urgent scientific and practical task – establishing mathematical models that describe the effect of operating modes of diesel engines on the content in the exhaust gases of a dangerous pollutant – particulate matter (PM). The purpose of the work was to create and study the accuracy and practical suitability of the calculation method estimating concentrations and emissions with exhaust gases PM by means of mathematical modeling of the influence on them of parameters that determine steady state and unsteady diesel operation modes. The studies were carried out on the basis of the motor stand of a 4ChN12/14 autotractor diesel equipped with a partial-flow system for diluting EG with air – MKT-2 microtunnels. Measurements mass and vol-ume concentrations – cpt (g/kg) and Cpt (g/mn3), mass – PTmass (g/h) and specific – PTp (g/kWh) PM emissions was carried out by the gravimetric method with errors of ± 3 .. 10% in accordance with the requirements of regulatory documents – ISO8178 standard, UNECE Rules R-49, R-96, etc. As parameters which determine the mode of opera-tion of the diesel engine, were considered: during the study steady-state modes – the number of revolutions of the engine crankshaft (n, min-1) and the load (L,%); in the study of unsteady modes – the parameters n and L and the rate of change over time – Δn/Δt and ΔL/Δt. A dependence has been established for indirectly determining the mass concentration of PM in the exhaust gases at steady and unsteady diesel operating modes, which are charac-terized by a duration of 10 ... 30 s and ranges of vari-ation of the parameters n, L, Δn/Δt and ΔL/Δt, given in di-mensionless form: 0.4 ... 0.8, 0.3 ... 1.0, -0.2 ... 0.2 and -0.35 ... 0.35, respectively. The deviation of the calculated and experimental data when using this dependence is ± 0.005-0.006 g/kg, which is comparable with the sensitivity limit of MKT-2. Keywords: diesel, exhaust gases, particulate matter, concentration, test mode, mathematical model, accuracy.

scholarly journals Prognostic Assessment of the Performance Parameters for the Industrial Diesel Engines Operated with Microalgae Oil

2021 ◽  
Vol 13 (11) ◽  
pp. 6482
Author(s):  
Sergejus Lebedevas ◽  
Laurencas Raslavičius
Keyword(s):  
Energy Efficiency ◽  
Diesel Engine ◽  
High Speed ◽  
Performance Parameters ◽  
Prognostic Assessment ◽  
High Speed Diesel ◽  
Microalgae Oil ◽  
The Difference ◽  
Smoke Opacity ◽  
Efficiency Indicators

A study conducted on the high-speed diesel engine (bore/stroke: 79.5/95.5 mm; 66 kW) running with microalgae oil (MAO100) and diesel fuel (D100) showed that, based on Wibe parameters (m and φz), the difference in numerical values of combustion characteristics was ~10% and, in turn, resulted in close energy efficiency indicators (ηi) for both fuels and the possibility to enhance the NOx-smoke opacity trade-off. A comparative analysis by mathematical modeling of energy and traction characteristics for the universal multi-purpose diesel engine CAT 3512B HB-SC (1200 kW, 1800 min−1) confirmed the earlier assumption: at the regimes of external speed characteristics, the difference in Pme and ηi for MAO100 and D100 did not exceeded 0.7–2.0% and 2–4%, respectively. With the refinement and development of the interim concept, the model led to the prognostic evaluation of the suitability of MAO100 as fuel for the FPT Industrial Cursor 13 engine (353 kW, 6-cylinders, common-rail) family. For the selected value of the indicated efficiency ηi = 0.48–0.49, two different combinations of φz and m parameters (φz = 60–70 degCA, m = 0.5 and φz = 60 degCA, m = 1) may be practically realized to achieve the desirable level of maximum combustion pressure Pmax = 130–150 bar (at α~2.0). When switching from diesel to MAO100, it is expected that the ηi will drop by 2–3%, however, an existing reserve in Pmax that comprises 5–7% will open up room for further optimization of energy efficiency and emission indicators.

scholarly journals Generational Differences in Support and Care of Individuals Diagnosed With Severe Mental Illness

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 94-94
Author(s):  
Deborah Finkel ◽  
Per Bulöw ◽  
Pia Bulöw ◽  
Monika Wilińska ◽  
Cristina Joy Torgé ◽  
...  
Keyword(s):  
Social Support ◽  
Mental Illness ◽  
Severe Mental Illness ◽  
Social Services ◽  
Generational Differences ◽  
System A ◽  
Care Systems ◽  
The Difference ◽  
Changes Over Time ◽  
Age Range

Abstract As part of the process of de-institutionalizing the Swedish mental health care system, a reform was implemented in 1995 moving responsibility for social support for people with severe mental illness (SMI) from the county to social services in the municipalities. In many ways, older people with SMI were neglected in this changing landscape of psychiatric care. To investigate possible generational differences in support experiences, two nonoverlapping cohorts were created from surveys conducted every fifth year between 1996 and 2011 in one middle-sized municipality in the south of Sweden, aiming to detect the needs for social support. Cohort 1 includes everyone detected at the 1996 survey aged 65 and 79 years (N = 92). Cohort 2 includes individuals first detected at the 2011 survey who were aged 65 to 79 (N = 104). Results indicates significant differences between the two cohorts in diagnosis, reflecting changes over time in diagnostic tendencies. Cohort 1 was on average 10 years older than Cohort 2, even within the restricted age range. After correcting for age, there were no differences between the two cohorts in education, functioning (CAN and GAF), or marital status. Although Cohort 1 experienced more days of institutionalization than Cohort 2 (median = 424.5 days vs. 382 days), the difference was not statistically significant. Cohort 2 had significantly higher additional subsidies and disposable income, as well as significantly higher income from other sources after retirement. Results indicate the changing demands that older adults with SMI will place on care systems.

scholarly journals Effects of Genotypes and Treatment on Oxygenscan Parameters in Sickle Cell Disease

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 811
Author(s):  
Camille Boisson ◽  
Minke A. E. Rab ◽  
Elie Nader ◽  
Céline Renoux ◽  
Celeste Kanne ◽  
...  
Keyword(s):  
Steady State ◽  
Sickle Cell Disease ◽  
Blood Cell ◽  
Sickle Cell ◽  
Red Blood Cell ◽  
Cell Disease ◽  
Oxygen Gradient ◽  
Acute Complication ◽  
Adults And Children ◽  
The Difference

(1) Background: The aim of the present study was to compare oxygen gradient ektacytometry parameters between sickle cell patients of different genotypes (SS, SC, and S/β+) or under different treatments (hydroxyurea or chronic red blood cell exchange). (2) Methods: Oxygen gradient ektacytometry was performed in 167 adults and children at steady state. In addition, five SS patients had oxygenscan measurements at steady state and during an acute complication requiring hospitalization. (3) Results: Red blood cell (RBC) deformability upon deoxygenation (EImin) and in normoxia (EImax) was increased, and the susceptibility of RBC to sickle upon deoxygenation was decreased in SC patients when compared to untreated SS patients older than 5 years old. SS patients under chronic red blood cell exchange had higher EImin and EImax and lower susceptibility of RBC to sickle upon deoxygenation compared to untreated SS patients, SS patients younger than 5 years old, and hydroxyurea-treated SS and SC patients. The susceptibility of RBC to sickle upon deoxygenation was increased in the five SS patients during acute complication compared to steady state, although the difference between steady state and acute complication was variable from one patient to another. (4) Conclusions: The present study demonstrates that oxygen gradient ektacytometry parameters are affected by sickle cell disease (SCD) genotype and treatment.

Nonlinear Vibrations of Viscoelastic Plane Truss Under Harmonic Excitation

2014 ◽  
Vol 14 (04) ◽  
pp. 1450009 ◽  
Author(s):  
Andrew Yee Tak Leung ◽  
Hong Xiang Yang ◽  
Ping Zhu
Keyword(s):  
Steady State ◽  
Fractional Derivatives ◽  
Harmonic Excitation ◽  
Homotopy Continuation ◽  
Response Curves ◽  
System A ◽  
Structural Responses ◽  
Voigt Model ◽  
Two Degree Of Freedom ◽  
Steady State Solutions

This paper is concerned with the steady state bifurcations of a harmonically excited two-member plane truss system. A two-degree-of-freedom Duffing system having nonlinear fractional derivatives is derived to govern the dynamic behaviors of the truss system. Viscoelastic properties are described by the fractional Kelvin–Voigt model based on the Caputo definition. The combined method of harmonic balance and polynomial homotopy continuation is adopted to obtain steady state solutions analytically. A parametric study is conducted with the help of amplitude-response curves. Despite its seeming simplicity, the mechanical system exhibits a wide variety of structural responses. The primary and sub-harmonic resonances and chaos are found in specific regions of system parameters. The dynamic snap-through phenomena are observed when the forcing amplitude exceeds some critical values. Moreover, it has been shown that, suppression of undesirable responses can be achieved via changing of viscosity of the system.

On the steady-state solution of the M/G/2 queue

1979 ◽  
Vol 11 (01) ◽  
pp. 240-255 ◽  
Author(s):  
Per Hokstad
Keyword(s):  
Steady State ◽  
General Solution ◽  
Laplace Transform ◽  
Queue Length ◽  
Joint Distribution ◽  
Length Distribution ◽  
Steady State Solution ◽  
Queue Length Distribution ◽  
The Difference ◽  
Number Of Customers

The asymptotic behaviour of the M/G/2 queue is studied. The difference-differential equations for the joint distribution of the number of customers present and of the remaining holding times for services in progress were obtained in Hokstad (1978a) (for M/G/m). In the present paper it is found that the general solution of these equations involves an arbitrary function. In order to decide which of the possible solutions is the answer to the queueing problem one has to consider the singularities of the Laplace transforms involved. When the service time has a rational Laplace transform, a method of obtaining the queue length distribution is outlined. For a couple of examples the explicit form of the generating function of the queue length is obtained.

Design and Performance of a Controlled Turbocharging System on Marine Diesel Engines

2006 ◽  
Author(s):  
Ioannis Vlaskos ◽  
Ennio Codan ◽  
Nikolaos Alexandrakis ◽  
George Papalambrou ◽  
Marios Ioannou ◽  
...  
Keyword(s):  
Steady State ◽  
Engine Performance ◽  
Operating Conditions ◽  
Electric Actuator ◽  
Engine Simulation ◽  
Engine Control System ◽  
Turbocharging System ◽  
Compressor Impeller ◽  
Marine Diesel ◽  
And Performance

The paper describes the design process for a controlled pulse turbocharging system (CPT) on a 5 cylinder 4-stroke marine engine and highlights the potential for improved engine performance as well as reduced smoke emissions under steady state and transient operating conditions, as offered by the following technologies: • controlled pulse turbocharging, • high pressure air injection onto the compressor impeller as well as into the air receiver, and • an electronic engine control system, including a hydraulic powered electric actuator. Calibrated engine simulation computer models based on the results of tests performed on the engine in its baseline configuration were used to design the CPT components. Various engine tests with CPT under steady state and transient operating conditions show the engine optimization process and how the above-mentioned technologies benefit engine behavior in both generator and propeller law operation.

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