Efficient constraint handling scheme for differential evolutionary algorithm in solving chemical engineering optimization problem

This paper introduces a new constraint handling scheme developed for the differential evolutionary algorithm to solve constrained optimization problems. The developed approach uses a repair algorithm based on the gradient information derived from the equality constraint set to correct infeasible solutions. A dominance-based selection scheme is also applied to incorporate constraints into the objective function. To illustrate the developed algorithm and to compare its efficiency with other tradition method, several test problems and chemical engineering optimization problems are used. A traditional constraint handling technique is compared; both in terms of solution quality and the number of function evaluations required. The performance of our developed scheme compares favorably with traditional penalty function method. Our developed algorithm can effectively handle constraints encountered in chemical engineering optimization problems.     

An integrated framework for on-line supervised optimization

In this paper, an integrated supervisory framework is envisaged for more robust on-line optimization and exception handling. This system takes advantage of the capabilities of real time evolution algorithm [Sequeira, S., Graells, M., Puigjaner, L. (2002). Real time evolution for Online Optimization of Continuous Processes. Industrial & Engineering Chemistry Research 41, 1815–1825] plus a fault diagnosis system (FDS) for managing abnormal situations. Both systems are part of a supervisory module which is responsible for handling plant incidences (faults and disturbances) by taking the appropriate corrective actions. Thus, a more satisfactory on-line performance is achieved, while reaction to incidence is enhanced by providing combined cause-effect information to plant managers. The implementation of the supervised real time evolution scheme has been performed using Matlab and the commercial simulation package HYSYS.Plant, taking advantage of their communication capabilities (COM technology). The developed fault diagnosis system comprises a detection module based on multivariate statistical techniques and an isolation module that uses an artificial neural network as a pattern classifier. The benefits of this framework are illustrated through a case study consisting in a debutanizer distillation column. The handling of various plant incidences, involving different sources and types of disturbances are considered. Finally, results of the supervised real time evolution (SRTE) are compared with those obtained using the standard real time optimization approach (RTO), showing superior performance in most of the cases.     

An efficient method for a numerical description of virgin olive oil color with only two absorbance measurements

Four polynomial expressions are obtained that provide a good approximation and an easy, rapid calculation of the chromatic coordinates and the chroma—L ^*, a ^*, b ^*, and C—for the illuminant C and the standard observer, for a virgin or extra virgin olive oil; absorbance is measured at only 480 and 670 nm. These are as follows: L ^*=0.556458(A₄₈₀)²−2.51145A₄₈₀+0.55504(A₆₇₀)²−8.53016A₆₇₀+98.4089; a ^*=0.177372(A₄₈₀)²+2.1363A₄₈₀+1.43254(A₆₇₀)²−0.789231A₆₇₀−13.9246; b ^*=−16.0277(A₄₈₀)²+79.8932A₄₈₀−5.06558(A₆₇₀)²+3.36169A₆₇₀+31.9405; C=−15.8439(A₄₈₀)²+78.9312A₄₈₀−5.26784(A₆₇₀)²+3.56917A₆₇₀+33.3927. These give acceptable results, making the method a practical alternative to the extremely laborious Commission Internationale d’Eclairage (CIE) L ^* a ^* b ^* system, by which 391 absorbance values must be measured individually, nanometer by nanometer, before applying more complex equations. The validity of the proposed method has been confirmed by comparison, using a set of 20 sample oils different from the set of 25 oils used to generate the order of the equations. The variations between the values provided by the proposed and standard methods, respectively, had a mean of 0.00 for each of the chromatic variables—L ^* , a ^* , b ^* , and C; SD were moderate (0.71, 0.52, 1.22, and 1.22, respectively); the root mean square and the R ²-terms also confirmed the validity of the method.     

Multi-objective optimization of reverse osmosis networks by lexicographic optimization and augmented epsilon constraint method

This study proposes a multi-objective optimization (MOO) of reverse osmosis (RO) networks for seawater desalination. The membrane transport model takes into consideration of the longitudinal variation of the velocity, the pressure, and the concentration in the membrane modules. The RO network with three type energy recovery device options (pressure exchanger (PX), Hydraulic Turbocharger, and turbine) is introduced. Lexicographic optimization (for calculation of a more effective payoff table) and augmented ε-constraint method (to avoid inefficient Pareto solutions) are proposed to solve the MOO problem. A fuzzy decision maker is introduced to derive the most efficient solution among Pareto-optimal solutions. Firstly, different energy recovery option studies show that using PX is seen to be the most profitable option. Exergy analysis is used to evaluate the contribution of the equipments in energy degradation. Secondly, the proposed multi-objective framework simultaneously optimizes the total annualized cost (TAC) and energy consumption. With the increases of weighting for the main objective function: TAC, the most efficient solution moves to lower TAC direction. Finally, system recovery rate is added as the third objective function. It is reasonable to stay at the appropriate system recovery rather than to increase up to its limit and generating high energetic losses.     

An efficient chained-hash-table strategy for collision handling in hard-sphere discrete particle modeling

We develop an efficient algorithm for handling collision events that is suitable for Discrete Particle Modeling (DPM) of dense gas–solid fluidization systems. We improve on previous strategies that are discussed in this paper as a byproduct. The core idea is centered on the use of dynamic crosswise linked data structures. This type of data structures enables an efficient updating and managing of lists of collision events associated with particles. In addition, a chained-hash-table strategy is proposed to efficiently process particle collision sequences. For systems of N_p particles, this strategy allows a complexity O(1) time per collision regarding the event list handling operations.     

An efficient preparation method for superabsorbent polymers

High water‐absorbent polyacrylates could be prepared by concentrated aqueous solution polymerization within a short time period, heating the monomer mixture by water bath. The influences of initiator content, bath temperature, crosslinker content (Cc), and degree of neutralization on water absorbency (Q) were investigated. The temperature changing of the monomer mixture during polymerization was thoroughly analyzed. The increase of initiator content as well as the increase of bath temperature results in the increase of water absorbency and reduces the crosslinking efficiency. The results are in conformity with Flory's network theory and also illustrate that lower crosslinking efficiency occurs when the polymerization rate is faster. An empirical relation of Q = 1.40 Cc^−0.665 is obtained and its exponent is very close to −0.6 in a derived relation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 119–124, 1999     

An efficient purification method for detonation nanodiamonds

This article reports the purification process of detonation soot to obtain pure nanodiamond powder. Nanodiamonds are synthesized by detonation using a high explosive mixture composed of trinitrotoluene and hexogen. The detonation of the charge leads to a powder containing nanodiamonds as well as metallic impurities and sp² carbon species. Further, to remove metallic particles, an unusual acidic treatment (hydrofluoric/nitric acids; i.e. fluorinated aqua regia) was set up. To eliminate sp² carbon species such as graphite and amorphous carbon, a thermal oxidation treatment was performed at 420 °C under air in a furnace during several hours. Transmission Electronic Microscopy, Raman spectroscopy, X-ray diffraction and Thermo-Gravimetric Analysis showed that this purification process is very efficient. From TGA measurements, a model of the carbon grain combustion was developed by considering graphitic shells surrounding the nanodiamond particles, and was used to demonstrate that the selective oxidation of graphite was experimentally realistic. Moreover, another model was set up from specific area measurements to evaluate the thickness of the functional groups surrounding the nanodiamonds after the oxidation of sp² carbonaceous species. The treatment described herein was achieved on several tens of grams of product and could be easily adapted to the industrial scale.     

An efficient numerical technique for solving one-dimensional batch crystallization models with size-dependent growth rates

In this work, an efficient numerical method is introduced for solving one-dimensional batch crystallization models with size-dependent growth rates. The proposed method consist of two parts. In the first part, a coupled system of ordinary differential equations (ODEs) for the moments and the solute concentration is numerically solved to obtain their discrete values in the time domain of interest. These discrete values are also used to get growth and nucleation rates in the same time domain. To overcome the issue of closure, a Gaussian quadrature method based on orthogonal polynomials is employed for approximating integrals appearing in the ODE system. In the second part, the discrete growth and nucleation rates along with the initial crystal size distribution (CSD) are used to construct the final CSD. The expression for CSD is obtained by applying the method of characteristics and Duhamel's principle on the given population balance model (PBM). The proposed method is efficient, accurate, and easy to implement in the computer. Several numerical test problems of batch crystallization processes are considered. For a validation, the results of the proposed technique are compared with those obtained using a high resolution finite volume scheme.     

Multiobjective differential evolution (MODE) for optimization of adiabatic styrene reactor

In this paper, a novel algorithm is proposed for solving multiobjective optimization problems. The proposed algorithm, multiobjective differential evolution (MODE), is applied to optimize industrial adiabatic styrene reactor considering productivity, selectivity and yield as the main objectives. Five combinations of the objectives are considered. Pareto set (a set of equally good solutions) obtained for all the cases is compared with results reported using non-dominated sorting genetic algorithm (NSGA). The results show that all objectives besides profit can be improved compared to those reported using NSGA and current operating conditions. The Pareto optimal front provides wide-ranging optimal operating conditions and an appropriate operating point can be selected based on the requirements of the user.     

New optimization method is highly suitable for chemical engineering applications

A new optimization method involving only elementary calculus represents a significant simplification over existing methods. It makes for the easy and rapid solution of many complex problems in chemical engineering. In addition to making use of the first derivative, as in most other methods, the new method also calls for the second derivative of the function to be optimized. When going from one point to another, the method consists essentially in adding simultaneously to each independent variable an increment which, for a given variable, is equal to the negative ratio of the first partial derivative to the second partial derivative, and so on until optimum conditions are reached. A few mathematical examples illustrate the speed of the new method and permit comparisons with other well known methods. Numerical applications pertaining to chemical engineering are also presented.     

NVH工程材料在轿车上优化设计的探讨

为了优化设计和降低噪声,从板件的声辐射特性开始,经声学灵敏度分析,测定车身各板件对噪声的贡献;选择NVH工程材料,形成设计方案,对设计方案进行测试验证。本文探讨了优化设计的过程和方法。     

An efficient method for enhancing convective heat transfer

A new efficient method for enhancing convective heat transfer in tubular heat exchangers is developed, which can be called the deep profiling method. The potential of the method is illustrated experimentally on a laboratory tube-in-tube heat exchanger.Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 38, No. 6, 2004, pp. 634–649.Original Russian Text Copyright © 2004 by Konoplev, Aleksanyan, Rytov, Berlin.     

An efficient and reliable predictive method for fluidized bed simulation

In past decades, the continuum approach was the only practical technique to simulate large‐scale fluidized bed reactors because discrete approaches suffer from the cost of tracking huge numbers of particles and their collisions. This study significantly improved the computation speed of discrete particle methods in two steps: First, the time‐driven hard‐sphere (TDHS) algorithm with a larger time‐step is proposed allowing a speedup of 20–60 times; second, the number of tracked particles is reduced by adopting the coarse‐graining technique gaining an additional 2–3 orders of magnitude speedup of the simulations. A new velocity correction term was introduced and validated in TDHS to solve the over‐packing issue in dense granular flow. The TDHS was then coupled with the coarse‐graining technique to simulate a pilot‐scale riser. The simulation results compared well with experiment data and proved that this new approach can be used for efficient and reliable simulations of large‐scale fluidized bed systems. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5320–5334, 2017     

An improved method for numerical solution of distillation processes

A new method for the numerical solution of a stagewise process is presented. The method consists of total linearization of all the equations in the distillation process, using the method of quasi-linearization. The resulting equations form a block-band matrix which can be readily solved by a method developed by the author. The method used for obtaining convergence is presented. The method has been tested for both binary and multi-component systems. The method has been compared with the Amundson-Pontinen method for a five component mixture. The method gives more rapid convergence. Numerical experiments indicate that the vapor and liquid flow rates are more stringent requirements than the bubble point.     

A shortcut method for the preliminary synthesis of process-technology pathways: An optimization approach and application for the conceptual design of integrated biorefineries

Synthesis and screening of technology alternatives is a key process-development activity in the process industries. Recently, this has become particularly important for the conceptual design of biorefineries. This work introduces a shortcut method for the synthesis and screening of integrated biorefineries. A structural representation (referred to as the chemical species/conversion operator) is introduced. It is used to track individual chemicals while allowing for the processing of multiple chemicals in processing technologies. The representation is used to embed potential configurations of interest. An optimization approach is developed to screen and determine optimum network configurations for various technology pathways using simple data. The solution to the optimization formulation provides a quick and effective method for screening and interconnecting the technological pathways and to distributing the flows over the network. Case studies are solved to illustrate the applicability of the proposed approach.     

An integrated numerical and experimental framework for modeling of CTB and GD1b ganglioside binding kinetics

A mathematical model is developed and validated for a multistep binding process between cholera toxin subunit B (CTB) and GD1b receptors that precedes cholera infection. To study the dynamics of the complex CTB‐GD1b binding mechanisms, cooperative binding effect and GD1b receptor aggregation in the host cell membrane are considered. More reliable parameters for the CTB‐GD1b binding kinetics are estimated by quantitatively calibrating the proposed multistep binding model against the experimental measurements obtained from the novel nanocube‐based biosensor. Specifically, a numerical scheme that includes the sensitivity analysis, parameter estimation and dynamic optimization is implemented for the model calibration. Through this scheme, identifiable model parameters are determined. After those selected parameters are estimated, the calibrated model and the experimental measurements were in reasonable agreement for different CTB and GD1b concentrations, which shows a promising approach for identification of the kinetics of CTB binding to the host cell membrane. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3882–3893, 2018     

Biased mutation-assembling: an efficient method for rapid directed evolution through simultaneous mutation accumulation

We have developed an efficient optimization technique, 'biased mutation-assembling', for improving protein properties such as thermostability. In this strategy, a mutant library is constructed using the overlap extension polymerase chain reaction technique with DNA fragments from wild-type and phenotypically advantageous mutant genes, in which the number of mutations assembled in the wild-type gene is stochastically controlled by the mixing ratio of the mutant DNA fragments to wild-type fragments. A high mixing ratio results in a mutant composition biased to favor multiple-point mutants. We applied this strategy to improve the thermostability of prolyl endopeptidase from Flavobacterium meningosepticum as a case study and found that the proportion of thermostable mutants in a library increased as the mixing ratio was increased. If the proportion of thermostable mutants increases, the screening effort needed to find them should be reduced. Indeed, we isolated a mutant with a 1200-fold longer activity half-life at 60 degrees C than that of wild-type prolyl endopeptidase after screening only 2000 mutants from a library prepared with a high mixing ratio. Our results indicate that an aggressive accumulation of advantageous mutations leads to an increase in the quality of the mutant library and a reduction in the screening effort required to find superior mutants.