scholarly journals Steady Modeling for an Ammonia Synthesis Reactor Based on a Novel CDEAS-LS-SVM Model

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
Zhuoqian Liu ◽  
Lingbo Zhang ◽  
Wei Xu ◽  
Xingsheng Gu
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Differential Evolution ◽  
Ammonia Synthesis ◽  
Fast Convergence ◽  
Operating Conditions ◽  
Synthesis Process ◽  
Plant Behavior ◽  
Svm Model ◽  
Simulation Results

A steady-state mathematical model is built in order to represent plant behavior under stationary operating conditions. A novel modeling using LS-SVR based on Cultural Differential Evolution with Ant Search is proposed. LS-SVM is adopted to establish the model of the net value of ammonia. The modeling method has fast convergence speed and good global adaptability for identification of the ammonia synthesis process. The LS-SVR model was established using the above-mentioned method. Simulation results verify the validity of the method.

Jet Engine Gas Path Analysis Based on Takeoff Performance Snapshots

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
A. Putz ◽  
S. Staudacher ◽  
C. Koch ◽  
T. Brandes
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Performance Model ◽  
Operating Conditions ◽  
Medium Size ◽  
Jet Engines ◽  
Transient Effects ◽  
Steady State Analysis ◽  
Simulation Results ◽  
State Analysis

Current engine condition monitoring (ECM) systems for jet engines include the analysis of on-wing gas path data using steady-state performance models. Such data, which are also referred to as performance snapshots, usually are taken during cruise flight and during takeoff. Using steady-state analysis, it is assumed that these snapshots have been taken under stabilized operating conditions. However, this assumption is reasonable only for cruise snapshots. During takeoff, jet engines operate in highly transient conditions with significant heat transfer occurring between the fluid and the engine structure. Hence, steady-state analysis of takeoff snapshots is subject to high uncertainty. Because of this, takeoff snapshots are not used for performance analysis in current ECM systems. We quantify the analysis uncertainty by transient simulation of a generic takeoff maneuver using a performance model of a medium size two-shaft turbofan engine with high bypass ratio. Taking into account the influence of the preceding operating regimes on the transient heat transfer effects, this takeoff maneuver is extended backward in time to cover the aircraft turnaround as well as the end of the last flight mission. We present a hybrid approach for thermal calculation of both the fired engine and the shutdown engine. The simulation results show that takeoff derate, ambient temperature, taxi-out (XO) duration and the duration of the preceding aircraft turnaround have a major influence on the transient effects occurring during takeoff. The analysis uncertainty caused by the transient effects is significant. Based on the simulation results, we propose a method for correction of takeoff snapshots to steady-state operating conditions. Furthermore, we show that the simultaneous analysis of cruise and corrected takeoff snapshots leads to significant improvements in observability.

A new model to predict the behaviour of cavitated squeeze-film bearings

1987 ◽  
Vol 411 (1841) ◽  
pp. 445-466
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Lift Force ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Successful Operation ◽  
New Model ◽  
Damping Coefficients ◽  
Stiffness Coefficients ◽  
Linear Damping

Squeeze-film bearings are used extensively to control vibration in rotor-bearing systems. No closed-form mathematical model exists to represent the stiffness and dam ping characteristics of a cavitated squeeze-film bearing when it is describing a non-circular, non-concentric orbit. In this paper nonlinear expressions are developed for the oil-film forces from which are derived two direct linear stiffness and two direct linear damping coefficients with all the cross stiffness and dam ping coefficients zero. The linearized stiffness coefficients and the damping coefficients are functions of the amplitude of the journal orbit. The dynamic lift-force which is fundamental to the successful operation of a cavitated squeeze-film bearing when designed without centralizing springs has not previously been predicted analytically. An expression is derived for this lift force. Its magnitude is shown to be dependent upon the amplitude of the steady-state orbit, that is, it is dependent upon the dynamic load. A numerical experiment is performed to assess the validity of the new model over a range of operating conditions.

scholarly journals Deactivation by sintering of the cobalt catalyst during the Fischer-Tropsch reaction

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Dounia Alihellal ◽  
Lemnouer Chibane ◽  
Mohamed El-Amine Slimani
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Active Sites ◽  
Cobalt Catalyst ◽  
Reaction Rates ◽  
Operating Conditions ◽  
Molar Ratio ◽  
Fischer Tropsch ◽  
Simulation Results ◽  
By Products

In the present work, the deactivation by sintering of cobalt-based catalyst during Fischer-Tropsch synthesis at low temperature was studied by numerical simulation. For this purpose, a mathematical model was developed. The obtained simulation results allowed us to highlight and improve the understanding of the deactivation phenomena of cobalt-based Fischer-Tropsch catalysts by sintering. The main results also show that the sintering phenomenon is strongly dependent on the operating conditions, in particular, the temperature, the pressure, and the H2/CO molar ratio, as well as the reaction by-products such as water. The results obtained can, therefore, be used to understand more the sintering mechanism which may be linked to the change in the concentration of the active sites and the reaction rates.

scholarly journals Modeling and Optimization of RFID Networks Planning Problem

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Hongshan Kong ◽  
Bin Yu
Keyword(s):  
Mathematical Model ◽  
Global Convergence ◽  
Differential Evolution ◽  
Local Convergence ◽  
Evolutionary Strategies ◽  
Planning Problem ◽  
Modeling And Optimization ◽  
Rfid Networks ◽  
Simulation Results

Aimed at solving the RFID networks planning problem, a mathematical model considering tag coverage and reader interference is presented. The DEEPSO algorithm that adds differential evolution and evolutionary strategies to the standard PSO is introduced to the optimization of RFID Networks Planning, which can improve the global convergence ability and particle diversity and can avoid falling into local convergence. According to the simulation results, compared with RFID networks planning by standard PSO, RFID networks planning by DEEPSO is superior.

Considerations about Maximum Temperature of Toroidal Transformers in Steady-State Conditions

2020 ◽  
Vol 7 (1) ◽  
pp. 22-29
Author(s):  
Adrian Pleșca ◽  
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Ambient Temperature ◽  
Electric Current ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Maximum Difference ◽  
Novel Method ◽  
Theoretical Results

In this paper, a novel method based on a thermal mathematical model which includes the main geometrical, physical and thermal parameters of the toroidal transformer has been developed in order to obtain the maximum temperature inside the transformer during steady-state operating conditions. The influence of electric current and ambient temperature on the maximum temperature has been investigated. To validate the proposed method, some experimental tests have been done. The analyzed transformer had a rated power of 2kVA and the rated primary voltage of 230V. There is a good correlation between experimental and theoretical results with a maximum difference of 3°C.

The Simulation of Six Phase PMSM Taking Iron Loss into Account

2012 ◽  
Vol 433-440 ◽  
pp. 7535-7540
Author(s):  
Dong Xing ◽  
Xiao Ning Zhang ◽  
Yong Ling Fu ◽  
Hai Tao Qi
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Dynamic Response ◽  
Iron Loss ◽  
Field Oriented Control ◽  
Three Phase ◽  
Simulation Results ◽  
Set Up ◽  
The Mathematical Model ◽  
Fast Dynamic

This paper studies the mathematical model considering iron loss in the d-q axis of six phase permanent magnetic synchronous motor (PMSM), through the expansion of Field-Oriented Control (FOC) based on three phase PMSM, the simulation model of six phase PMSM under environment of simulink7.0 is set up, which has fast dynamic response, high steady-state precision, and has no problems about current balance compared to dual three phase PMSM. In order to get an accurate simulation results, this mathematical model takes iron loss into account. The simulation results show that iron loss have bad effects on the performance of PMSM especially affect the dynamic response, and to reduce the bad effects, the resistance of the motor core should be increased.

Design of Urea-SCR Model of a Feedforward Controller Based on Simulation in Diesel Engine

2012 ◽  
Vol 562-564 ◽  
pp. 1924-1927
Author(s):  
Bao Yi Wang ◽  
Qian Wang
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Accurate Performance ◽  
Feedforward Controller ◽  
Simulation Results ◽  
Scr Model

Using a mathematical model, a feedforward controller model of Urea-SCR (selective catalytic reduction, SCR) in diesel engine is realized. At steady-state conditions, the simulated NOX concentration shows great consistence with the experimental value in the downstream of the converter. It can be seen that the simulation results show comparatively accurate performance of the model with the converter temperature changing linearly in the range from 450K to 750K.

Steady-State Operation Analysis for a Three-Winding Single-Phase Capacitor Motor

2015 ◽  
Vol 713-715 ◽  
pp. 1027-1030
Author(s):  
Jin Hui Zeng ◽  
Jian Guo Deng
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Power Supply ◽  
Single Phase ◽  
Experimental Results ◽  
Calculation Formula ◽  
Voltage Unbalance ◽  
Operation Analysis ◽  
Steady State Operation ◽  
Simulation Results

The steady-state mathematical model of Smith-connection three-winding single-phase capacitor motor is established, and the capacitance calculation formula in minimum voltage unbalance condition is deduce .Based on this, by MATLAB simulated program, a operation simulation of Smith single phase capacitor motor that in single-phase 220V power supply and in single-phase 380V power supply is developed. The simulation results agree with the experimental results.

scholarly journals Experimental investigation and thermal analysis of coupler-rocker ball bearing

2020 ◽  
Vol 24 (6 Part A) ◽  
pp. 3781-3793
Author(s):  
Abdullah Jamil ◽  
Bin Baharom ◽  
Alemu Lemma ◽  
Tadimalla Rao
Keyword(s):  
Mathematical Model ◽  
Thermal Analysis ◽  
Experimental Investigation ◽  
Steady State ◽  
Applied Load ◽  
Ball Bearing ◽  
Linear Trend ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Ball Bearings

Ball bearings are widely used in many machineries and industrial applications. Thermal behaviour of oscillating ball bearings is unknown due to its complex pendulum-like motion and is discussed in this research. In this research, the effect of operating conditions of the oscillating bearing performing coupler-rocker motion on the heat generation is experimentally investigated and verified using mathematical model. For this purpose, a coupler-rocker bearing testing rig was designed and fabricated and the test bearing is splash-lubricated in an oil sump. The loading of test bearing was done using two extension springs. The applied load on the bearing was varied from 0 to 750 N while the crank rpm was varied from 1200 rpm to 1800 rpm. Three lubricant grades were used namely, SAE30, SAE40, and SAE50. Experimental results showed that the temperature of coupler-rocker bearing approaches steady-state at about 12 minutes for all cases. The steady-state temperatures at variable conditions are observed to follow a linear trend.

scholarly journals Estimation of parameters characterizing a steady-state synthesis process with nonlinear microorganism growth kinetics

2022 ◽  
Vol 11 (4) ◽  
pp. 561-569
Author(s):  
Yu. L. Gordeeva ◽  
B. A. Ul’yanov ◽  
E. L. Gordeeva
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Numerical Experiment ◽  
Dilution Rate ◽  
Growth Kinetics ◽  
Technology Implementation ◽  
Theoretical Basis ◽  
Lactic Acid Production ◽  
Synthesis Process ◽  
Estimation Of Parameters

The paper describes a theoretical basis developed for estimating the parameters of a steady-state biotechnological process characterized by nonlinear microorganism growth kinetics. This study aimed to obtain a common methodological basis for estimating input parameters that determine actual technology implementation, taking into account all possible restrictions on the concentration of incoming substrate Sf (g/l) and dilution rate D (h-1 ). The theory development was based on a mathematical model describing one of the most common processes of lactic acid production. This mathematical model includes three mass balance equations (for biomass, substrate, and product), as well as an equation of microorganism growth kinetics. The study established relations for calculating the ultimate value of the dilution rate D ult at a given Sf , relations for the maximum and minimum values of Sf , as well as Sf and D providing the maximum productivity value QP, g/(l·h), where QP = PD (P – product concentration, g/l). These relations were designed to calculate the parameters of possible process implementation for two options at the same value of QP: two values of D calculated for a given Sf and two values of Sf calculated for a given D. A numerical experiment is described using the constants of the mathematical model confirmed by foreign studies. This numerical experiment is illustrated using an Sf-D dependence pattern determining an acceptable value range for Sf and D, with the separate calculation of parameters according to Sf sections. For each of these sections, calculation formulas are provided. It is concluded that the developed theoretical basis is sufficiently general in nature to be applied to biotechnological processes that involve other kinetic relations, as well as microorganism strains creating by-products and using raw materials that are employed to reproduce the substrate in the process of synthesis.

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