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Optimizing thermal energy storage in rectangular unit: Exploring the impact of moving fin with phase change material

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JOURNAL OF ENERGY STORAGE 2024年 99卷

作者： Izgi, Burak Demirag, Hueseyin Zahit Yozgat Bozok Univ Dept Mech Engn TR-66200 Yozgat Turkiye

This research presents an innovative moving fin design for a latent heat storage unit, with the objective of improving thermal performance. The methodology integrates numerical simulation, a machine learning approach, and a multi-objective genetic optimization algorithm (NSGA-II). The study optimizes fin parameters, such as fin velocity (Vf), V f ), fin thickness (tf), t f ), fin length (Lf) L f ) and initial fin position (yf). y f ). The optimization process aims to maximize both power (P) P ) and stored energy per mass (Em), E m ), assigning equal importance to both criteria. The outcomes reveal a considerable rise in power with minor compromises in stored energy per mass. The incorporation of moving fins in rectangular enclosure with PCM leads to a significant power boost while preserving stored latent energy with minimal compromise. In comparison to the no-fin condition, fixed 1-fin and fixed 3-fin configurations lead to stored energy losses of 4.16 % and 11.73 %, respectively, accompanied by power increases of 20.48 % and 51.17 %, respectively. Conversely, the optimized condition for maximum power with moving fins incurs a mere 2.73 % stored energy loss but achieves a remarkable 173.92 % increase in power. The optimized design parameters for maximizing power (P) P ) include Vf f = 22.5 x 10-3 mm/s, yf f = 60 mm, tf= f = 2 mm, and Lf f = 40 mm.

关键词： Thermal energy storage genetic algorithm optimization Dynamic thermal systems

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Evolutionary offloading in an edge environment

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EGYPTIAN INFORMATICS JOURNAL 2021年第3期22卷 257-267页

作者： Zakaryia, Samah A. Ahmed, Safaa A. Hussein, Mohamed K. Fac Comp & Informat Dept Comp Sci Ismailia Egypt

Due to increasing complexity of mobile applications, and limited computation resources of smart mobile devices, the quality of service requirements of mobile application can be enhanced by offloading the computation tasks of the mobile applications to edge servers, such as cloudlets, which exist at the edge of wireless networks. However, improper placement of mobile tasks on the edge servers may increase the waiting time and the transmission time. This, in turn, will increase the response time, and eventually violates the quality of service. This paper proposes an effective offloading strategy in a mobile edge environment using the queuing networks and an evolutionary algorithm, namely the genetic algorithm (GA). The queuing network is used to model the waiting time and the service time of the mobile tasks on the edge servers. The genetic algorithm finds the best allocation of mobile tasks on the edge servers to minimize tasks response time considering the transmission times and the load conditions on edge servers represented by the waiting times and the service times which are calculated using the queuing network. The proposed GA-based offloading algorithm is compared with another evolutionary algorithm, namely particle swarm optimization (PSO). Experimental evaluations show that the GA-based offloading algorithm outperforms both of round robin offloading and the PSO-based offloading algorithms, and effectively improves mobile applications response time. (C) 2021 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Computers and Artificial Intelligence, Cairo University.

关键词： Mobile edge computing Computation offloading genetic algorithm optimization Evolutionary optimization Particle swarm optimization

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Zinc Oxide Thin Films Characterization, AFM, XRD and X-ray Reflectivity

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EXPERIMENTAL TECHNIQUES 2016年第4期40卷 1297-1306页

作者： Solookinejad, Gh. Rozatian, A. S. H. Habibi, M. H. Islamic Azad Univ Dept Phys Marvdasht Branch Marvdasht Iran Univ Isfahan Dept Phys Esfahan *** Iran Univ Isfahan Dept Chem Esfahan *** Iran

In this study, surface structures of two zinc oxide (ZnO) thin films, prepared by sol-gel spin and dip-coating methods, were investigated. Ex situ Atomic Force Microscopy (AFM), X-ray diffraction (XRD), and X-ray reflectivity measurements were carried out in order to study the surface structure. XRD measurements showed nanostructured ZnO thin films with well-defined orientations. Fractal analysis was applied on the AFM data to illustrate the surface morphology of thin films. Fractal analysis provided a precious depiction of irregularities found in ZnO thin films and revealed that both interface width W and lateral correlation length xi are strongly affected by coating method. Calculations showed that the film that was prepared by dip-coating had correlation length, interface width and fractal dimension of 56.2, 2.3, and 2.2 nm, respectively. These parameters for spin-coated sample were 354.8, 8.5, and 2.64 nm, respectively. optimization of X-ray reflectivity by genetic algorithm optimization revealed structural parameters of thin films such as surface and interface roughness and thickness of the films. These calculations showed that dip-coated thin film has a smooth surface, whereas spin-coated thin film has a rough surface.

关键词： Zinc Oxide Surface Structure Spin and Dip Coatings genetic algorithm optimization

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Parametric Analysis and Design optimization of a Pyrotechnically Actuated Device

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INTERNATIONAL JOURNAL OF AERONAUTICAL AND SPACE SCIENCES 2016年第3期17卷 409-422页

作者： Han, Doo-Hee Sung, Hong-Gye Jang, Seung-Gyo Ryu, Byung-Tae Korea Aerosp Univ Dept Aerosp & Mech Engn Gyeonggi 10540 South Korea Agcy Def Developmen4 Adv Prop Technol Ctr POB 35 Daejeon 34060 South Korea

A parametric study based on an unsteady mathematical model of a pyrotechnically actuated device was performed for design optimization. The model simulates time histories for the chamber pressure, temperature, mass transfer and pin motion. It is validated through a comparison with experimentally measured pressure and pin displacement. Parametric analyses were conducted to observe the detailed effects of the design parameters using a validated performance analysis code. The detailed effects of the design variables on the performance were evaluated using the one-at-a-time (OAT) method, while the scatter plot method was used to evaluate relative sensitivity. Finally, the design optimization was conducted by employing a genetic algorithm (GA). Six major design parameters for the GA were chosen based on the results of the sensitivity analysis. A fitness function was suggested, which included the following targets: minimum explosive mass for the uniform ignition (small deviation), light casing weight, short operational time, allowable pyrotechnic shock force and finally the designated pin kinetic energy. The propellant mass and cross-sectional area were the first and the second most sensitive parameters, which significantly affected the pin's kinetic energy. Even though the peak chamber pressure decreased, the pin kinetic energy maintained its designated value because the widened pin cross-sectional area induced enough force at low pressure.

关键词： Pyrotechnically actuated device Performance analysis Sensitivity analysis genetic algorithm optimization

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New method for power allocation of multi-power sources considering speed-up transient vibration of planetary power-split HEVs driveline system

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2019年 128卷 1-18页

作者： Wang, Feng Zhang, Jian Xu, Xing Cai, Yingfeng Zhou, Zhiguang Sun, Xiaoqiang Jiangsu Univ Automot Engn Res Inst Zhenjiang 212013 Jiangsu Peoples R China Chongqing Univ Technol Minist Educ Key Lab Adv Manufacture Technol Automobile Parts Chongqing 400054 Peoples R China Chery Automobile Co Ltd Powertrain Technol Ctr New Energy Dev Dept Wuhu 241009 Peoples R China

One of the major issues for hybrid electric vehicles (HEVs) powertrain is the torsional vibration in the process of speed-up condition, which is unavoidable. The broader goal of this article is to re-examine the classical gear transmission machinery transient vibration problem in the context of a 4 + N degree of freedom nonlinear torsional system that essentially describes a planetary coupling transmission system (PCTS) of HEVs example, and further provide a new method for power allocation of multi-power sources considering speed-up transient vibration of planetary power-split HEVs driveline system. In particular, resonant amplifications during acceleration, as excited by angular displacement-based meshing stiffness of gear teeth, are investigated using a nonlinear torsional model, and the transient vibration predictions are successfully compared with test bench results. Then a quasi-linear model during acceleration process is proposed and numerically solved to obtain the transient vibration acceleration as well as its envelope curve. Dynamic response results of PCTS are also successfully compared and analyzed under different speed-allocation rules. Finally, an improved genetic algorithm method is applied to construct optimal relationship between the motor speeds and vehicle speeds, and the influences of vibration character and energy consumption are successfully considered in multi-optimized function. Experimental results under the speed-up condition show that transient vibration acceleration of the optimized powertrain is decreased within the safe range, thus new power-allocation solutions provide more insight to the enhancement of planetary power-split HEVs quality. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Transient vibration-induced power allocation Angular displacement-based meshing stiffness Planetary coupling transmission system Multi-power source machinery genetic algorithm optimization

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A GA optimization for lithium-ion battery equalization based on SOC estimation by NN and FLC

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INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS 2015年 73卷 318-328页

作者： Zhang, ShuMei Yang, Lin Zhao, XiaoWei Qiang, Jia Xi Shanghai Jiao Tong Univ Inst Automot Elect Technol Shanghai 200240 Peoples R China

An intelligent control proposal for battery equalization is presented by genetic algorithm optimization integrated with fuzzy logic control-neural network algorithm. First, an effective two-stage DC/DC converter architecture is developed, which pave the way for the hardware module. Then, an equivalent circuit model in weighted combination with ampere-hour counting method is adopted by fuzzy logic control scheme to obtain static SOC estimation. Then the dynamic battery SOC is precisely estimated on basis of static SOC by means of neural network. The most important is the genetic algorithm optimization for battery equalization to improve the energy efficiency and time efficiency of the equalization system. Finally, certification of simulation is demonstrated to validate the proposed novel equalization scheme. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Fuzzy logic control-neural network algorithm Two-stage DC/DC converter Equivalent circuit model Ampere-hour counting method genetic algorithm optimization

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Automated process design and optimization of membrane-based CO₂ capture for a coal-based power plant

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JOURNAL OF MEMBRANE SCIENCE 2018年 563卷 820-834页

作者： Lee, Sunghoon Binns, Michael Kim, Jin-Kuk Hanyang Univ Dept Chem Engn 222 Wangsimni Ro Seoul 04763 South Korea Dongguk Univ Dept Chem & Biochem Engn 30Pildong Ro 1 Gil Seoul 04620 South Korea

A systematic optimization framework is proposed with the aim to automate the design of multi-stage membrane processes for CO2 capture from flue gas of a coal-fired power plant. This framework utilizes a superstructure approach to determine the optimal configuration of membrane systems and identify the most appropriate operating conditions in a holistic manner. Certain design specifications are satisfied through the use of penalty functions which are used in a genetic algorithm (GA) optimization method employed to identify design solutions at or near to the global optimal point. Sensitivity analysis is used to analyze multi-stage membrane designs to understand the effects of different structural and operating parameters on the economics of membrane-based carbon capture. As part of a case study the proposed design framework is applied to design membrane processes for the capture of CO2 from a 600 MWe coal-fired power plant. Fixed membrane permeance and selectivity values are used to analyze sensitivities with respect to costing and structural design parameters. Additionally, the Robeson upper bound correlation between CO2 permeance and CO2/N-2 selectivity is used within this framework to identify the optimal membrane properties which give economical separation of CO2 and N-2. It is found that membranes having at least 4000 GPU CO2 permeance and over 50 of CO2/N-2 selectivity with a commercial available module gave the optimal performance and would be a good guideline for future membrane material development. Also, if different membrane properties are used in each stage (in a multi-stage configuration) then using a higher CO2 permeance for the first stage (e.g. 6000 GPU CO2 permeance and CO2/N-2 selectivity of 40) and higher selectivity membranes are used for subsequent downstream membrane stages (e.g. 1334 GPU CO2 permeance and CO2/N-2 selectivity of 72) helps to reduce the electricity consumption and product purity which can reduce the overall cost of CO2 capture.

关键词： Membrane process CO2 capture Superstructure approach genetic algorithm optimization Gas permeation

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Design of a Traveling-Wave Slot Array Power Divider Using the Method of Moments and a genetic algorithm

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 2015年第12期63卷 3981-3987页

作者： Rengarajan, Sembiam R. Lynch, Jonathan J. Calif State Univ Northridge Dept Elect & Comp Engn Northridge CA 91330 USA HRL Labs LLC Malibu CA 90265 USA

A 1-to-25-way uniform amplitude and linear phase power divider, using slotted rectangular waveguides in the traveling-wave mode, is designed to cover the 71-77-GHz band. The design employs the scattering parameters of three-port couplers computed from the method of moments (MoM) solution to the integral equation of the slot aperture field. Subsequent genetic algorithm (GA) optimization is aimed at maximizing the return loss and combining efficiency and flatness of coupling amplitudes in the whole frequency band. GA utilizes the MoM solution to the coupled integral equations of slot apertures in the entire power divider structure. Simulations indicate the optimized power divider yielding better than 26-dB return loss and greater than 86% efficiency in the 71-77-GHz band for the power divider combiner connected back to back. Computed MoM results have been validated by the commercial code HFSS and also by experimentally measured results. The measured insertion loss of two back-to-back divider-combiners is about 2 dB.

关键词： genetic algorithm optimization method of moments power combiner power divider slot array slotted waveguide traveling wave

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Disturbance observer-based terminal sliding mode control for effective performance of a nonlinear vibration energy harvester

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JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES 2020年第12期31卷 1495-1510页

作者： Yousefpour, Amin Hosseinloo, Ashkan Haji Yazdi, Mohammad Reza Hairi Bahrami, Arash Univ Tehran Coll Engn Sch Mech Engn North Kargar St Tehran *** Iran MIT Dept Mech Engn Cambridge MA 02139 USA

We propose a new scheme to control the coexisting attractors in a bistable piezomagnetoelastic power generator. Coexisting periodic or chaotic attractors frequently occur in nonlinear energy harvesters. For effective performance of the energy harvester, the system is desired to operate on the high-energy periodic orbit. Therefore, a controller may be used to force the system to operate on the high-energy orbit. In the present research, a disturbance observer-based terminal sliding mode control with input saturation is proposed to push the system from low-energy periodic and chaotic attractors to high-energy periodic attractors. Furthermore, to minimize the energy required for the controller, a genetic algorithm optimization is employed to determine the bound of the input saturation and parameters of the controller. A major advantage of the proposed control technique is tracking control while control input limitations, significant concerns for energy harvesting purpose, are present. The Lyapunov stability theorem of the closed-loop system is proven in the presence of control input saturation and external disturbance. In addition to the primary resonance, superharmonic resonance is considered. The numerical results show that the proposed method can successfully control and shift the vibration energy harvesting system between different attractors in the presence of uncertainty and with minimal control energy budget.

关键词： energy harvesting coexisting attractors chaos control terminal sliding mode control input saturation genetic algorithm optimization

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Optimal design of passive-adaptive pendulum tuned mass damper for the global vibration control of offshore wind turbines

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WIND ENERGY 2021年第6期24卷 573-595页

作者： Bertollucci Colherinhas, Gino Petrini, Francesco de Morais, Marcus Vinicius Girao Bontempi, Franco Univ Brasilia Fac Tecnol Campus Darcy Ribeiro Brasilia DF Brazil Sapienza Univ Roma Sch Engn Via Eudossiana 18 Rome Italy

This paper presents an optimal design procedure for a pendulum tuned mass damper (PTMD) to mitigate the global structural vibrations of offshore wind turbines (OWTs) in the fore-aft and side-side directions. The procedure is tested to the design of a PTMD to be applied to the 5-MW benchmark baseline monopile wind turbine proposed by the National Renewable Energy Lab (NREL). The computation of wind and wave spectra, as well as the evaluation of the hydrodynamic and aerodynamic loads, is conducted by using an in-house built MATLAB (R) routine working together with an ANSYS (R) 3-D finite element (FE) global model for evaluating the resultant peak displacement response at the OWT hub by a power spectral density (PSD) analysis. In order to validate the OWT FEM model, a result comparison is made with the NREL OpenFAST, finding good matches between the two codes. An in-house built genetic algorithm (GA) toolbox, coded in MATLAB (R), is then used to optimally design the parameters of a PTMD with a simplified 2-degrees-of-freedom (2DOF) model. The chosen GA fitness function targets the minimization of the peak response of the primary structure as evaluated by the 2DOF model. The design parameters of the PTMD are the flexural rigidity and damping, the mass ratio and pendulum length. After the 3-D FE model of the OWT without any control device has been validated, and the PTMD has been optimized by the simplified 2DOF model, the performances of the PTMD are examined on a 3-D global FE OWT + PTMD model in ANSYS (R).

关键词： genetic algorithm optimization offshore wind turbine pendulum tuned mass damper power spectral density analysis structural control

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