In precise fuel circuit systems, the filtration of particulate impurities seriously affects the efficiency and service life of various components. For filtration process intensification of high-pressure fuel laser per...
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In precise fuel circuit systems, the filtration of particulate impurities seriously affects the efficiency and service life of various components. For filtration process intensification of high-pressure fuel laser perforated filters, the two-phase flow characteristics in filters is studied. The size, position and number of filtration holes are taken as optimization variables, and take the filtration efficiency and flow pressure drop as optimizationobjectives. Computational fluid dynamics (CFD) is used to simulate the two-phase motion of continuous phase and discrete particles in a periodic unit. Artificial neural networks (ANN) are utilized for objectives prediction, and the NSGA-II genetic algorithm is employed for multi-objective optimization, resulting in the Pareto front solution set. Furtherly, the reasonable solution is selected by introducing TOPSIS to ensure that two optimization indexes are relatively smaller and balanced. The optimized filter element scheme allows the filter to have a pressure drop of less than 3.2 MPa under high pressure and a filtration efficiency of over 80% for spherical particle impurities with a diameter of 5 μm or more.
Ultra-high performance concrete(UHPC)has gained a lot of attention lately because of its remarkable properties,even if its high cost and high carbon emissions run counter to the current development *** lower the cost ...
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Ultra-high performance concrete(UHPC)has gained a lot of attention lately because of its remarkable properties,even if its high cost and high carbon emissions run counter to the current development *** lower the cost and carbon emissions of UHPC,this study develops a multi-objective optimization framework that combines the non-dominated sorting genetic algorithm and 6 different machine learning methods to handle this *** key features of UHPC are filtered using the recursive feature elimination approach,and Bayesian optimization and random grid search are employed to optimize the hyperparameters of the machine learning prediction *** optimal mix ratios of UHPC are found by applying the multi-objective algorithm non-dominated sorting genetic algorithm-Ⅲ and multiobjective evolutionary algorithm based on adaptive geometric *** results are evaluated by technique for order preference by similarity to ideal solution and validated by *** outcomes demonstrate that the compressive strength and slump flow of UHPC are correctly predicted by the machine learning *** multiobjectiveoptimization produces Pareto fronts,which illustrate the trade-off between the mix’s compressive strength,slump flow,cost,and environmental sustainability as well as the wide variety of possible *** research contributes to the development of cost-effective and environmentally sustainable UHPC,and aids in robust,intelligent,and sustainable building practices.
The cascaded multi-layer packed bed thermal energy storage (TES) unit with varying fill ratios is proposed to enhance its thermal performance. A concentric dispersion model for simulating thermal fluid heat transfer i...
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The cascaded multi-layer packed bed thermal energy storage (TES) unit with varying fill ratios is proposed to enhance its thermal performance. A concentric dispersion model for simulating thermal fluid heat transfer is developed and experimentally validated. Based on this, four designs are explored to examine the effect of the filling ratio of phase change materials with different melting points on the thermal performance of the packed bed TES system, including that of balanced-layer, top-heavy-layer, middle-heavy-layer and bottom-heavy-layer. The multi-factor and multi-objective optimization is conducted by response surface and factor analysis methods. Differs from the previous studies that only designed several configurations with different phase change material filling ratios, the present sudy focuses on the interaction between the filling ratio and the thermal performances, as well as the optimal filling ratio of each layer to achieve the best thermal performance. The results show that the bottom-heavy-layer has the shortest charging time of 950 min and the highest energy utilization of 61.72 %, while the top-heavy-layer has the highest charging exergy efficiency of 84.7 % and the largest TES capacity of 96.88 MWh. As for the multi-objective optimization, the optimized value of comprehensive evaluation indicator F is 1.7112, and the corresponding charging time, energy utilization, TES capacity, and charging exergy efficiency is 778 min, 0.62, 99.76 MWh, and 0.83, respectively. This research establishes a foundation for the advanced optimization of phase change material filling ratios and comprehensive system-level evaluation.
The axial field flux-switching magnetic gear composite machine (AFFSMGCM) is a new type of magnetic field modulation machine with a dual-rotor. Due to the complicated structure of the AFFSMGCM and the nonlinear charac...
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The axial field flux-switching magnetic gear composite machine (AFFSMGCM) is a new type of magnetic field modulation machine with a dual-rotor. Due to the complicated structure of the AFFSMGCM and the nonlinear characteristic of dual magnetic fields coupling, a divided-layer varying-network magnetic circuit (VNMC) method is developed to optimize the machine to obtain a high calculation accuracy and reduce operation time. First, an accurate VNMC model is established according to the magnetic field distribution of an AFFSMGCM. The magnetic field coupling of the rotor and stator permanent magnets (PMs) is performed by the rotary magnetic modulation ring (RMMR). Thus, the magnetic circuit of the RMMR is divided into two layers to reduce the influence of magnetic saturation and leakage flux on the calculation accuracy of the permeances. Then the particle swarm optimization (PSO) method is used to achieve multi-objective optimization of the AFFSMGCM based on the divided-layer VNMC for achieving a large torque, low torque ripple and high efficiency. Next, a multi-physics field coupling analysis is carried out to verify the optimized AFFSMGCM. Finally, a prototype is built and experiments are carried out to validate the AFFSMGCM.
Minimizing the maximum revisit time of satellite constellations is crucial for the rapid detection of changes, especially in disaster, defense and intelligence contexts. This study aims to design a Walker Delta satell...
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Minimizing the maximum revisit time of satellite constellations is crucial for the rapid detection of changes, especially in disaster, defense and intelligence contexts. This study aims to design a Walker Delta satellite constellation to cover T & uuml;rkiye's geography, collecting data with short revisit times and low costs. A Matlab script was created to calculate the maximum revisit time parametrically in the Systems Tool Kit software by configuring satellite constellation configurations, and this script was integrated into the ModeFrontier software to create an optimization loop using the multi-objective Genetic Algorithm method. The optimization has four objectives: minimizing the number of satellites, the number of orbital planes, the vertical half-angle of the sensor, and the maximum revisit time. As a result of the study, it was concluded that to achieve a maximum revisit time of fewer than 120 minutes in the region where data is to be collected, there should be a minimum of 33 satellites, at least 11 orbital planes, and a minimum vertical half-angle of 15 degrees for the sensor. A satellite constellation configuration was chosen from the optimized Paretooptimal solution set, meeting cost and revisit time criteria.
Equations of state using the Statistical Associating Fluid Theory (SAFT EoS) have found tremendous success in the thermodynamic modeling of ionic liquids (ILs) and mixtures. Traditionally, SAFT EoS parameters are fit ...
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Equations of state using the Statistical Associating Fluid Theory (SAFT EoS) have found tremendous success in the thermodynamic modeling of ionic liquids (ILs) and mixtures. Traditionally, SAFT EoS parameters are fit to pure component pressure-volume-temperature (PVT) (density) data and vapor pressure data. We have recently combined the PC-SAFT EoS with entropy scaling theory to correlate and predict the viscosity of ILs and IL mixtures. We found that the PC-SAFT EoS parameters for ionic liquids regressed to PVT data can sometimes lead to relatively large deviations in the viscosity correlations, especially at high pressure. Here, we investigate the effect of including viscosity data along with PVT data for the PC-SAFT parameter regression of two series of 1-nalkyl-3-methyl imidazolium ionic liquids ([CnMIm][Tf2N] and [CnMIm][BF4]). From analyzing the Pareto fronts, the inclusion of viscosity data to PVT data for PC-SAFT parameters resulted in only a small loss in accuracy for the density, but with much improved viscosity correlations through entropy scaling. We found that the parameter sets obtained from density and viscosity data regression are less prone to numerical pitfalls, i.e. fictitious SAFT critical points, than the parameter sets obtained from PVT data alone. In addition, the predicted (kij=0) phase equilibrium (VLE) of ionic liquids and mixtures with CO2, CH4, and water were equal to, if not better than the predictions using PVT data alone. Overall, the use of pure PVT and viscosity data in the parameterization of PCSAFT yields a more widely applicable prediction method for both thermodynamic and transport properties.
Cryocooler-based zero boil-off schemes are promising for long-term storage of cryogenic propellants. To date, no studies have addressed the fluid-thermal coupling between key components of the zero boil-off system, as...
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Cryocooler-based zero boil-off schemes are promising for long-term storage of cryogenic propellants. To date, no studies have addressed the fluid-thermal coupling between key components of the zero boil-off system, as well as the trade-offs among the cooling power, insulation performance and energy utilization efficiency. To predict and optimize the performance of a cryocooler-based zero-boil-off system, a systemic model integrating theoretical calculations and computational fluid dynamics was developed. Additionally, a multi-objective optimization method was designed based on a modified hyperplane generation approach and a self-adaptive crossover operator. The accuracy of the model was validated using the results of liquid nitrogen experiments from the literature. On the same computation platform, the proposed optimization method demonstrated superior capabilities in avoiding local optima and accelerating convergence compared with the original Non-dominated Sorting Genetic Algorithm-III: the temperature uniformity of the cold shield improved by at least 10.44 %, and the time cost was reduced by 32.25 %. In addition, conflicts were identified among the cooling power, temperature uniformity of the cold shield, and parasitic heat leakage, whereas the temperature uniformity showed a positive correlation with heat leakage through multilayer insulation. These findings provide guidelines for the multi-objective design of cryogenic propellant storage systems for future space missions.
Varying results in cutter wear and cutting performance can be observed based on different selections of shield operational parameters, particularly in hard rock or soil with a high quartz content. Improperly selecting...
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Varying results in cutter wear and cutting performance can be observed based on different selections of shield operational parameters, particularly in hard rock or soil with a high quartz content. Improperly selecting operational parameters may result in excessive wear and reduced cutting performance, leading to longer project duration and increased costs. Furthermore, it is still challenging to balance cutter wear and cutting performance. To address these issues, a multi-objective optimization (MOO) framework based on the Light Gradient Boosting Machine (LightGBM) algorithm and the enhanced non-dominated sorting genetic-II (NSGA-II) algorithm is proposed to predict and optimize the cutter wear and cutting performance. To validate this framework, a shield tunneling project in China is presented. The results show that the efficiency and accuracy of predicting and optimizing the two objectives have been improved compared with other common methods. This MOO framework is valuable for operators to formulate rational operational control strategies.
A multi-energy complementary heating system (MEHS) is essential for the development of low-carbon building heating. However, limited research has been conducted on the optimal heat load allocation. In light of heat ba...
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A multi-energy complementary heating system (MEHS) is essential for the development of low-carbon building heating. However, limited research has been conducted on the optimal heat load allocation. In light of heat balancing, heat source operation, and energy resource limits, this study proposes a MEHS model based on life cycle assessment, with costs, CO2 emissions, and energy efficiency serving as the objective functions. By optimizing, the Pareto frontier solution is obtained, and the relationships between the objective and the heat load allocation ratios of heating subsystems are analyzed. Finally, the impact of the power industry's low-carbon transition and increasing carbon trading prices on the MEHS is investigated. The results show that the optimal heat load allocation ratios for the air source heat pump, natural gas-fired, biomass-fired, coal-fired, thermal storage electric boiler, and ground source heat pump heating subsystems are 44.42 %, 13.41 %, 0.71 %, 32.18 %, 0.56 %, and 8.72 %, respectively. Costs and CO2 emissions during operation account for more than 80 % of the total life cycle impact. CO2 emissions can be reduced by 16 % when the power grid CO2 emission factor is reduced to 0.2530 kg CO2/kWh, and by 4.5 % when the carbon price increases to 200 CNY/t.
Reformed methanol high-temperature proton exchange membrane fuel cell (RM HT-PEMFC) systems demonstrate potential for both mobile and stationary applications. However, optimizing key variables is challenging due to th...
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Reformed methanol high-temperature proton exchange membrane fuel cell (RM HT-PEMFC) systems demonstrate potential for both mobile and stationary applications. However, optimizing key variables is challenging due to the complex coupling of heat flows across various temperature levels. This study develops a combined cooling, heating and power system by integrating the RM HT-PEMFC with a double-effect LiBr-H2O absorption refrigeration cycle. The proposed system is optimized using the Non-dominated Sorting Genetic Algorithm II (NSGA-II), targeting system exergy efficiency, specific CO2 emissions, and exergy cost per unit product. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is employed to determine the optimal values of objectives: an exergy efficiency of 43.12%, specific CO2 emissions of 0.510 kg/kWh, and exergy cost per unit product of 167.59 USD/GJ, representing improvements of 20.73%, reduction of 17.10%, and 1.07% compared to baseline. The optimized ranges for key parameters are identified as follows: stack temperature (173.94-179.91 degrees C), steam to carbon ratio (1.78-1.80), current density (0.20-0.40 A/cm2), and cathode stoichiometry (2.29-2.52).
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