scholarly journals Simultaneous simulation and optimization of multiple dividing wall columns

2021 ◽  
Author(s):  
Tobias Seidel ◽  
Lena-Marie Ränger ◽  
Thomas Grützner ◽  
Michael Bortz
Keyword(s):  
Optimization Problem ◽  
Calculation Procedure ◽  
Process Variables ◽  
Fast Calculation ◽  
New Approach ◽  
Simulation And Optimization ◽  
Highly Nonlinear ◽  
Commercial Process ◽  
Model Equations ◽  
Process Simulator

In this work we present a new approach that we use to simulate and optimize multiple dividing wall columns at the same time. Instead of considering all model equations as constraints and all process variables as optimization variables in a large and highly nonlinear optimization problem we only incorporate a subset of the model equations as constraints and a subset of the process variables as optimization variables. The remaining process variables are calculated from this subset by a robust and fast calculation procedure. This calculation procedure also ensures that the remaining model equations are satisfied. A comparison with the commercial process simulator Aspen Plus shows that with the new approach multiple dividing wall columns can be optimized more stable and better solutions are found. Moreover the time needed to find an optimal design decreases significantly.

scholarly journals Traveltime inversion for 2‐D anomaly structures

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1481-1487 ◽  
Author(s):  
Danilo R. Velis
Keyword(s):  
Optimization Problem ◽  
Inversion Method ◽  
Unknown Parameters ◽  
New Approach ◽  
Traveltime Inversion ◽  
Velocity Models ◽  
Highly Nonlinear ◽  
Small Set ◽  
A Cell ◽  
Parametric Functions

This work presents a traveltime inversion method that uses parametric functions to represent 2‐D anomaly structures. These functions are described by a small set of unknown parameters which in turn are obtained after solving a highly nonlinear optimization problem via simulated annealing (SA). The procedure favors neither smooth nor high contrasting anomalies and keeps the number of unknowns very small so as to make the problem tractable using SA. Yet the strategy allows one to accommodate a large class of velocity models. Results indicate that this new approach typically yields better images than a standard linearized inversion based on a cell parameterization scheme.

PREDICTIVE SIMULATION AND OPTIMIZATION ORIENTED MODELING FOR THE EXTRACTION OF METAL IONS FROM SOLUTIONS INTO A NOVEL BIS-SCHIFF BASE

2019 ◽  
pp. 1-8
Author(s):  
F. S. Nworie ◽  
S. O. Ngele ◽  
J. C. Onah
Keyword(s):  
Metal Ions ◽  
Metal Concentration ◽  
Acid Concentration ◽  
Aqueous Media ◽  
Industrial Effluents ◽  
Ligand Concentration ◽  
Simulation And Optimization ◽  
Chemometric Technique ◽  
Model Equations ◽  
Level Of Significance

Metal ions present in waste samples, industrial effluents, acid mines and other aqueous media constitute a serious challenge in different human activities. Solvent extraction a technique for preconcentration, separation and identification of trace amount of metal ions coupled with multivariate chemometric technique was used for the determination of Fe(II) and Cr(III) from solutions in the presence of bis(salicylidene)ethylenediamine (SALEN). The influence of main extraction variables affecting the extraction efficiency was simultaneously studied and regression model equations illustrating the relationship between variables predicted. The extraction parameters (time of extraction, acid concentration, ligand concentration, temperature and metal concentration) were optimized using experimental designs with the contributions of the various parameters to extraction of the metal ions bound to the complexone evaluated using SPSS19.0 software. The statistically determined simulated models for the parameters were R2 = 0.946, 0.727, 0.793, 0.53, 0.53, 1.000 and F- values of 70.400, 13. 285, 15.348, 4.646 and 2.569×105 respectively for time of extraction, acid concentration, ligand concentration, temperature and metal concentration for Cr (III). For Fe (II), R2 = 0.243, 0.371, 0.519, 0.446, 1.000 and F-values of 0.964, 2.953, 4.310, 3.216 and 2.516×105 for time of extraction, acid concentration, ligand concentration, temperature and metal concentration respectively. The level of significance of the models as predicted was both lower than 5% making it feasible, efficient, reproducible and accurate. This means that metal ions at the conditions stated could be removed from waste samples, industrial effluents, acid mines and other aqueous media with extension in industrial scale application.

scholarly journals Control Force Recalculation for Balancing Problems

2019 ◽  
Vol 19 (05) ◽  
pp. 1941010
Author(s):  
Bálint Bodor ◽  
László Bencsik ◽  
Tamás Insperger
Keyword(s):  
Optimization Problem ◽  
Control Mechanism ◽  
Numerical Differentiation ◽  
Open Loop ◽  
Second Step ◽  
Control Force ◽  
New Approach ◽  
Numerical Errors ◽  
Linearized System ◽  
Control Forces

Understanding the mechanism of human balancing is a scientifically challenging task. In order to describe the nature of the underlying control mechanism, the control force has to be determined experimentally. A main feature of balancing tasks is that the open-loop system is unstable. Therefore, reconstruction of the trajectories using the measured control force is difficult, since measurement inaccuracies, noise and numerical errors increase exponentially with time. In order to overcome this problem, a new approach is proposed in this paper. In the presented technique, first the solution of the linearized system is used. As a second step, an optimization problem is solved which is based on a variational principle. A main advantage of the method is that there is no need for the numerical differentiation of the measured data for the calculation of the control forces, which is the main source of the numerical errors. The method is demonstrated in case of a human stick balancing.

scholarly journals An efficient wavefield inversion for transversely isotropic media with a vertical axis of symmetry

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. R195-R206 ◽  
Author(s):  
Chao Song ◽  
Tariq Alkhalifah
Keyword(s):  
High Resolution ◽  
Optimization Problem ◽  
Source Function ◽  
Transversely Isotropic ◽  
Vertical Axis ◽  
Trade Off ◽  
Transversely Isotropic Media ◽  
Highly Nonlinear ◽  
Isotropic Media ◽  
Axis Of Symmetry

Conventional full-waveform inversion (FWI) aims at retrieving a high-resolution velocity model directly from the wavefields measured at the sensor locations resulting in a highly nonlinear optimization problem. Due to the high nonlinearity of FWI (manifested in one form in the cycle-skipping problem), it is easy to fall into local minima. Considering that the earth is truly anisotropic, a multiparameter inversion imposes additional challenges in exacerbating the null-space problem and the parameter trade-off issue. We have formulated an optimization problem to reconstruct the wavefield in an efficient matter with background models by using an enhanced source function (which includes secondary sources) in combination with fitting the data. In this two-term optimization problem to fit the wavefield to the data and to the background wave equation, the inversion for the wavefield is linear. Because we keep the modeling operator stationary within each frequency, we only need one matrix inversion per frequency. The inversion for the anisotropic parameters is handled in a separate optimization using the wavefield and the enhanced source function. Because the velocity is the dominant parameter controlling the wave propagation, it is updated first. Thus, this reduces undesired updates for anisotropic parameters due to the velocity update leakage. We find the effectiveness of this approach in reducing parameter trade-off with a distinct Gaussian anomaly model. We find that in using the parameterization [Formula: see text], and [Formula: see text] to describe the transversely isotropic media with a vertical axis of symmetry model in the inversion, we end up with high resolution and minimal trade-off compared to conventional parameterizations for the anisotropic Marmousi model. Application on 2D real data also indicates the validity of our method.

scholarly journals A General Framework for Portfolio Theory. Part III: Multi-Period Markets and Modular Approach

Risks ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 60
Author(s):  
Stanislaus Maier-Paape ◽  
Andreas Platen ◽  
Qiji Jim Zhu
Keyword(s):  
General Framework ◽  
Optimization Problem ◽  
Risk Measure ◽  
Efficient Frontier ◽  
Portfolio Theory ◽  
Trading Strategies ◽  
Performance Criteria ◽  
Market Model ◽  
Constant Weight ◽  
New Approach

This is Part III of a series of papers which focus on a general framework for portfolio theory. Here, we extend a general framework for portfolio theory in a one-period financial market as introduced in Part I [Maier-Paape and Zhu, Risks 2018, 6(2), 53] to multi-period markets. This extension is reasonable for applications. More importantly, we take a new approach, the “modular portfolio theory”, which is built from the interaction among four related modules: (a) multi period market model; (b) trading strategies; (c) risk and utility functions (performance criteria); and (d) the optimization problem (efficient frontier and efficient portfolio). An important concept that allows dealing with the more general framework discussed here is a trading strategy generating function. This concept limits the discussion to a special class of manageable trading strategies, which is still wide enough to cover many frequently used trading strategies, for instance “constant weight” (fixed fraction). As application, we discuss the utility function of compounded return and the risk measure of relative log drawdowns.

scholarly journals A New Metaheuristic Inspired by the Vapour-Liquid Equilibrium for Continuous Optimization

2018 ◽  
Vol 8 (11) ◽  
pp. 2080 ◽  
Author(s):  
Enrique Cortés-Toro ◽  
Broderick Crawford ◽  
Juan Gómez-Pulido ◽  
Ricardo Soto ◽  
José Lanza-Gutiérrez
Keyword(s):  
Equilibrium State ◽  
Optimization Problem ◽  
Optimization Problems ◽  
Molar Fraction ◽  
Chemical System ◽  
Decision Variable ◽  
Liquid Equilibrium ◽  
Acceptance Probability ◽  
Promising Alternative ◽  
Highly Nonlinear

In this article, a novel optimization metaheuristic based on the vapour-liquid equilibrium is described to solve highly nonlinear optimization problems in continuous domains. During the search for the optimum, the procedure truly simulates the vapour-liquid equilibrium state of multiple binary chemical systems. Each decision variable of the optimization problem behaves as the molar fraction of the lightest component of a binary chemical system. The equilibrium state of each system is modified several times, independently and gradually, in two opposite directions and at different rates. The best thermodynamic conditions of equilibrium for each system are searched and evaluated to identify the following step towards the solution of the optimization problem. While the search is carried out, the algorithm randomly accepts inadequate solutions. This process is done in a controlled way by setting a minimum acceptance probability to restart the exploration in other areas to prevent becoming trapped in local optimal solutions. Moreover, the range of each decision variable is reduced autonomously during the search. The algorithm reaches competitive results with those obtained by other stochastic algorithms when testing several benchmark functions, which allows us to conclude that our metaheuristic is a promising alternative in the optimization field.

Optimal Viscous Damper Placement Using Level Set Topology Optimization Method

2010 ◽  
Author(s):  
Masoud Ansari ◽  
Amir Khajepour ◽  
Ebrahim Esmailzadeh
Keyword(s):  
Topology Optimization ◽  
Level Set ◽  
Discrete Optimization ◽  
Optimization Problem ◽  
Minimum Energy ◽  
Optimization Method ◽  
Discrete Optimization Problem ◽  
Placement Problem ◽  
New Approach ◽  
Optimal Damping

Vibration control has always been of great interest for many researchers in different fields, especially mechanical and civil engineering. One of the key elements in control of vibration is damper. One way of optimally suppressing unwanted vibrations is to find the best locations of the dampers in the structure, such that the highest dampening effect is achieved. This paper proposes a new approach that turns the conventional discrete optimization problem of optimal damper placement to a continuous topology optimization. In fact, instead of considering a few dampers and run the discrete optimization problem to find their best locations, the whole structure is considered to be connected to infinite numbers of dampers and level set topology optimization will be performed to determine the optimal damping set, while certain number of dampers are used, and the minimum energy for the system is achieved. This method has a few major advantages over the conventional methods, and can handle damper placement problem for complicated structures (systems) more accurately. The results, obtained in this research are very promising and show the capability of this method in finding the best damper location is structures.

Principal Component Analysis of Correlated WEDM Performance Characteristics during Machining ZC63/SiCP MMCs

2014 ◽  
Vol 14 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Thella Babu Rao ◽  
A. Gopala Krishna
Keyword(s):  
Principal Component Analysis ◽  
Quality Index ◽  
Optimization Problem ◽  
Principal Component ◽  
Component Analysis ◽  
Machining Process ◽  
Total Quality ◽  
Process Variables ◽  
Optimal Process ◽  
Pulse On Time

AbstractThe present investigation proposes the optimization of the wire electrical discharge machining process for machining ZC63/SiCP metal matrix composite. SiC particulate size and its percentage with the matrix are considered as the process variables along with the most significant WEDM variables such as pulse-on time, pulse-off time and wire tension. In view of quality cut, surface roughness, metal removal rate and kerf are considered as the process responses. Since, these responses are correlated with each other and they need to be optimized simultaneously. Therefore, the problem is treated as multi-response optimization problem. Principal component analysis (PCA) has been implemented to convert the multi-objective optimization problem in to single objective optimization problem by converting the multiple correlated responses in to the total quality index. Taguchi's robust optimization technique has been adopted to derive the set optimal process parameters which maximize the total quality index. The derived optimal process responses are confirmed with the experimental validation tests. ANOVA is conducted find the importance of the chosen process variables on the overall quality of the machined component. The practical possibility of the obtained optimal process performance is observed using SEM studies.

Parameter extraction of solar photovoltaic models via quadratic interpolation learning differential evolution

2020 ◽  
Vol 4 (11) ◽  
pp. 5595-5608
Author(s):  
Guojiang Xiong ◽  
Jing Zhang ◽  
Dongyuan Shi ◽  
Lin Zhu ◽  
Xufeng Yuan
Keyword(s):  
Differential Evolution ◽  
Optimization Problem ◽  
Parameter Extraction ◽  
Solar Photovoltaic ◽  
Multimodal Optimization ◽  
Quadratic Interpolation ◽  
Highly Nonlinear

The parameter extraction problem of solar photovoltaic (PV) models is a highly nonlinear multimodal optimization problem. In this paper, quadratic interpolation learning differential evolution (QILDE) is proposed to solve it.

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