Browse
Recent Submissions
New records verified within the last 120 days
Showing records 74 to 98 of 263. [First] Page: 1 2 3 4 5 6 7 8 Last
A Low-Carbon Scheduling Method of Flexible Manufacturing and Crane Transportation Considering Multi-State Collaborative Configuration Based on Hybrid Differential Evolution
Zhengchao Liu, Liuyang Xu, Chunrong Pan, Xiangdong Gao, Wenqing Xiong, Hongtao Tang, Deming Lei
February 10, 2024 (v1)
Keywords: crane transportation, flexible manufacturing, hybrid differential evolution, low-carbon scheduling, multi-state collaborative configuration
With increasingly stringent carbon policies, the development of traditional heavy industries with high carbon emissions has been greatly restricted. Manufacturing companies surveyed use multifunctional machining machines and variable speed cranes, as the lack of rational planning results in high energy wastage and low productivity. Reasonable scheduling optimization is an effective way to reduce carbon emissions, which motivates us to work on this research. To reduce the comprehensive energy consumption of the machining process and transportation process in an actual manufacturing environment, this paper addresses a new low-carbon scheduling problem of flexible manufacturing and crane transportation considering multi-state collaborative configuration (LSP-FM&CT-MCC). First, an integrated energy consumption model based on multi-state machining machines and cranes is established to optimize the overall energy efficiency of the production process. Then, a new hybrid differential evolution... [more]
An Efficient and Accurate Approach to Electrical Boundary Layer Nanofluid Flow Simulation: A Use of Artificial Intelligence
Amani S. Baazeem, Muhammad Shoaib Arif, Kamaleldin Abodayeh
February 10, 2024 (v1)
Keywords: boundary layer flow, consistency, explicit scheme, neural network, stability
Engineering and technological research groups are becoming interested in neural network techniques to improve productivity, business strategies, and societal development. In this paper, an explicit numerical scheme is given for both linear and nonlinear differential equations. The scheme is correct to second order. Additionally, the scheme’s consistency and stability are guaranteed. Backpropagation of Levenberg−Marquardt, the effect of including an induced magnetic field in a mathematical model for electrical boundary layer nanofluid flow on a flat plate, is quantitatively investigated using artificial neural networks. Later, the model is reduced into a set of boundary value problems, which are then resolved using the suggested scheme and a shooting strategy. The outcomes are also contrasted with earlier studies and the MATLAB solver bvp4c for validation purposes. In addition, neural networking is also employed for mapping input to outputs for velocity, temperature, and concentration p... [more]
Experimental and Computational Fluid Dynamic—CFD Analysis Simulation of Heat Transfer Using Graphene Nanoplatelets GNP/Water in the Double Tube Heat Exchanger
Carlos C. X. S. Lima, Alvaro A. V. Ochoa, José A. P. da Costa, Frederico D. de Menezes, João V. P. Alves, Julia M. G. A. Ferreira, Clara C. A. Azevedo, Paula S. A. Michima, Gustavo N. P. Leite
February 10, 2024 (v1)
Keywords: double tube heat exchangers, graphene, heat transfer, nanofluids
This study investigates and compares the experimental heat transfer performance and simulation via computational fluid dynamics (CFD) of graphene nanoplatelets (GNP) and water nanofluids GNP/water in the double-tube-type heat exchanger (DTHE). Tests were conducted with water/water and GNP/water fluids, with the nanofluid for the hot-fluid circuit and water for the cold-fluid circuit, with counterflow direction, varying the nanofluid concentrations by weight (wt%) at 0.0125%, 0.025%, and 0.050%, the operating temperature at 50 and 60 °C, and Reynolds numbers between 2000−6000. The results showed that 0.025 wt% GNP presented better thermal performance, with a 28% increase in the temperature gain. The 0.025 wt% GNP had slightly better performance for the Nusselt number (Nu), and the 0.05 wt% GNP had a slightly better thermal effectiveness. The comparison between the experimental values showed good agreement with those calculated by empirical correlations and the CFD model, with maximum an... [more]
A Flexible Heat Exchanger Network Synthesis Method Adapted to Multi-Operation Conditions
Sibei Ji, Li Zhou, Bozhou Dang, Xu Ji, Yagu Dang
February 10, 2024 (v1)
Keywords: flexibility, Heat Exchanger Network, multiperiod, stream phase changes
This paper presents a flexible HEN (heat exchanger network) synthesis methodology for designing a multiperiod HEN with streams involving phase changes. The methodology is based on an MINLP (mixed integer nonlinear programming) model, identification of critical points, and flexibility index analysis considering phase changes. A nominal multiperiod HEN topology is constructed in the first step. Then each process operating condition’s critical points and flexibility index are calculated to verify the feasibility of the designed HEN under multiple operating conditions. To verify the validity of the method, the proposed methodology will be applied to a case study on an ammonia synthesis process heat transfer network design based on renewable energy. The results show that the method can obtain a flexible heat transfer network that is cost-effective and adaptable to multi-condition production for green ammonia synthesis.
Model-Based Condition Monitoring of Modular Process Plants
Philipp Wetterich, Maximilian M. G. Kuhr, Peter F. Pelz
February 10, 2024 (v1)
Keywords: condition monitoring, fault diagnosis, modularization, soft sensors
The process industry is confronted with rising demands for flexibility and efficiency. One way to achieve this is modular process plants, which consist of pre-manufactured modules with their own decentralized intelligence. Plants are then composed of these modules as unchangeable building blocks and can be easily re-configured for different products. Condition monitoring of such plants is necessary, but the available solutions are not applicable. The authors of this paper suggest an approach in which model-based symptoms are derived from a few measurements and observers that are based on the manufacturer’s knowledge. The comparisons of redundant observers lead to residuals that are classified to obtain symptoms. These symptoms can be communicated to the plant control and are inputs to an easily adaptable diagnosis. The implementation and validation at a modular mixing plant showcase the feasibility and potential of this approach.
Applying a Novel Image Recognition Curve-Fitting Control Strategy Combined with a Cloud Monitoring Technique into an Electric Self-Driving Vehicle (ESDV) to Improve Its Operation Efficiency
Hwa-Dong Liu, Ping-Jui Lin, Shan-Xun Lai, Chang-Hua Lin, Shoeb-Azam Farooqui
February 10, 2024 (v1)
Keywords: cloud monitoring technique, electric self-driving vehicle, Hough line detection method, image recognition curve-fitting control strategy
This study aims to develop an image recognition curve-fitting (IRCF) control strategy integrated with a cloud monitoring technique for application in electric self-driving vehicles (ESDVs) to improve their operation efficiency. The study focuses on an electric vehicle designed to reduce the carbon emissions and promote sustainability. The main camera, combined with the IRCF control strategy, was used to control the ESDV to enhance its operational efficiency. The proposed ESDV employs a pair of cameras to capture images and transmit them to the cloud-based web monitoring platform in real time. This allows the researchers to adjust the control parameters and promptly remove the road obstacles. The ESDV is equipped with a horn, two ultrasonic sensors, and an LED display, which can instantly detect the obstacles ahead of and behind the vehicle. When there are obstacles on the road, the vehicle will automatically stop, and the LED display will provide a visual representation of the obstacle... [more]
CNN-LSTM to Predict and Investigate the Performance of a Thermal/Photovoltaic System Cooled by Nanofluid (Al2O3) in a Hot-Climate Location
Abdulelah Alhamayani
February 10, 2024 (v1)
Subject: Materials
Keywords: CNN-LSTM, GRU, LSTM, PV, PV/T
The proposed study aims to estimate and conduct an investigation of the performance of a hybrid thermal/photovoltaic system cooled by nanofluid (Al2O3) utilizing time-series deep learning networks. The use of nanofluids greatly improves the proposed system’s performance deficiencies due to the rise in cell temperature, and time-series algorithms assist in investigating its potential in various regions more accurately. In this paper, energy balance methods were used to generate the hybrid thermal/photovoltaic system’s performance located in Tabuk, Saudi Arabia. Moreover, the generated dataset for the hybrid thermal/photovoltaic system was utilized to develop deep learning algorithms, such as the hybrid convolutional neural network (CNN) and long short-term memory (LSTM), in order to estimate and investigate the thermal/photovoltaic performance. The models were evaluated based on several performance metrics such as mean absolute percentage error (MAPE), root mean square error (RMSE), mea... [more]
Enabling Safe and Sustainable Hydrogen Mobility: Circular Economy-Driven Management of Hydrogen Vehicle Safety
Mohammad Yazdi, Rosita Moradi, Reza Ghasemi Pirbalouti, Esmaeil Zarei, He Li
February 10, 2024 (v1)
Subject: Environment
Keywords: adaptive DEMATEL, decision-making, fuel cell electric vehicles (FCEVs), hydrogen vehicle safety, net-zero emissions, sustainable development goals
Hydrogen vehicles, encompassing fuel cell electric vehicles (FCEVs), are pivotal within the UK’s energy landscape as it pursues the goal of net-zero emissions by 2050. By markedly diminishing dependence on fossil fuels, FCEVs, including hydrogen vehicles, wield substantial influence in shaping the circular economy (CE). Their impact extends to optimizing resource utilization, enabling zero-emission mobility, facilitating the integration of renewable energy sources, supplying adaptable energy storage solutions, and interconnecting diverse sectors. The widespread adoption of hydrogen vehicles accelerates the UK’s transformative journey towards a sustainable CE. However, to fully harness the benefits of this transition, a robust investigation and implementation of safety measures concerning hydrogen vehicle (HV) use are indispensable. Therefore, this study takes a holistic approach, integrating quantitative risk assessment (QRA) and an adaptive decision-making trial and evaluation laborat... [more]
Hydraulic Design of Sediment-Trapping Basin in Wadis Using Empirical Equations and Deposition Processes
Abubakr Taha Bakheit Taha, Ali Aldrees, Ahmed Moustafa Ahmed Moussa
February 10, 2024 (v1)
Keywords: annual total load, empirical equations, King Fahad Dam, sediment-trapping basin, Wadi Bishah
Reservoirs overflow during flood season because of sedimentation cycles, which severely affects their effectiveness. Siltation is a major problem in dams constructed in waterways in arid and semi-arid areas. Therefore, the reservoirs in wadis lose their capacity due to sedimentation. This study determines an optimal design of the trapping basin on steep slope areas for Wadi Bishah in the Asir region of southwestern Saudi Arabia. The empirical design criteria of the sediment-trapping basin is used to mitigate the effects of sedimentation in the King Fahd Dam. The empirical design of the trapping basin constructed upstream of the dam located in the wadi is presented. Moreover, the annual suspended and bed sediment load (Qs and Qb) techniques for estimating the volume of sediments are used, and the relationship between the sediment trapping efficiency and size is determined. The sediment trapping in Wadi Bishah upstream sediment-trapping basins is selected to reduce the amount of sediment... [more]
Numerical Modeling of Ammonia-Fueled Protonic-Ion Conducting Electrolyte-Supported Solid Oxide Fuel Cell (H-SOFC): A Brief Review
Md. Mosfiqur Rahman, Abdalla M. Abdalla, Lukman Ahmed Omeiza, Veena Raj, Shammya Afroze, Md. Sumon Reza, Mahendra Rao Somalu, Abul K. Azad
February 10, 2024 (v1)
Keywords: ammonia-fueled solid oxide fuel cell, design analysis, Fuel Cells, numerical modeling, physical phenomena, protonic conducting fuel cells, solid oxide fuel cell
Solid oxide fuel cells with protonic ion conducting electrolytes (H-SOFCs) are recognized and anticipated as eco-friendly electrochemical devices fueled with several kinds of fuels. One distinct feature of SOFCs that makes them different from others is fuel flexibility. Ammonia is a colorless gas with a compound of nitrogen and hydrogen with a distinct strong smell at room temperature. It is easily dissolved in water and is a great absorbent. Ammonia plays a vital role as a caustic for its alkaline characteristics. Nowadays, ammonia is being used as a hydrogen carrier because it has carbon-free molecules and prosperous physical properties with transportation characteristics, distribution options, and storage capacity. Using ammonia as a fuel in H-SOFCs has the advantage of its ammonia cracking attributes and quality of being easily separated from generated steam. Moreover, toxic NOx gases are not formed in the anode while using ammonia as fuel in H-SOFCs. Recently, various numerical st... [more]
Consistency Checks for Pressure-Volume-Temperature Experiment of Formation Oil and Gas at High Temperature
Libin Zhao, Yongling Zhang, Yuanyuan He, Jianchao Shi, Xiaopei Wang, Jiabang Song, Haiyang Yu
February 10, 2024 (v1)
Subject: Materials
Keywords: consistency check, gas condensate, high temperature, PVT experiment, volatile oil
The oil and gas phase behavior of high temperature is complex and changeable, which is usually obtained by PVT experiments. The accuracy of the experiment data plays a crucial role in the reserve evaluation and development plan of oil and gas reservoirs. However, the current PVT experiment consistency checks are not suitable for high-temperature reservoir conditions. This paper proposes a systematic check method for the PVT experiment data consistency at high temperature. These checks revise the material balance method, Hoffman method, and equilibrium constant method by using the equilibrium constant calculation method at high temperature. The consistency check of component data and constant volume depletion experiment data is carried out by combining the three improved methods with the component check method, so as to judge the experiment data accurately. In this paper, two high-temperature reservoir fluids—gas condensate sample fluid X and volatile oil sample fluid Y—are selected to... [more]
Mechanism and Main Control Factors of CO2 Huff and Puff to Enhance Oil Recovery in Chang 7 Shale Oil Reservoir of Ordos Basin
Tong Wang, Bo Xu, Yatong Chen, Jian Wang
February 10, 2024 (v1)
Keywords: Chang 7 shale oil reservoir, CO2 huff-n-puff, enhance oil recovery (EOR), heterogeneity
The Chang 7 shale oil reservoir has low natural energy and is both tight and highly heterogeneous, resulting in significant remaining oil after depletion development. CO2 huff and puff (huff-n-puff) is an effective way to take over from depletion development. Numerous scholars have studied and analyzed the CO2 huff-n-puff mechanism and parameters based on laboratory core sample huff-n-puff experiments. However, experimental procedures are not comprehensive, leading to more general studies of some mechanisms, and existing CO2 huff-n-puff experiments struggle to reflect the effect of actual reservoir heterogeneity due to the limited length of the experimental core samples. In this paper, CO2 huff-n-puff laboratory experiments were performed on short (about 5 cm) and long (about 100 cm) core samples from the Chang 7 shale oil reservoir, and the microscopic pore fluid utilization in the short samples was investigated using a nuclear magnetic resonance (NMR) technique. We then analyzed and... [more]
Combustion Process of the Compound Supply CNG Engine
Zhiqiang Zhu, Defu Zhang, Yunjing Jiao
February 10, 2024 (v1)
Keywords: compound gas supply, natural gas engine, stratified combustion
In order to study the lean combustion process of a natural gas engine by separating the combustor, a spark ignition natural gas engine with separated combustors was retrofitted from a S195 single-cylinder diesel engine. Methods: The electronic control system controlled the gas supply and the spark plug ignition. A low pressure injection valve was set in the inlet pipe to form a lean mixture while a high pressure injection valve was placed in the subsidiary chamber to create a rich mixture, which was then ignited and injected into the main combustor, where the lean mixture was subsequently ignited again to achieve stratified combustion. Results: The test results showed that steady ignition is feasible in the system and verified the impact of the shape of the main combustor on HC, the impact of channel diameter on NOX production, and the impact of the ratios of high-pressure gas and low-pressure gas on HC and NOX. The combustion conditions of high-pressure gas and low-pressure gas in the... [more]
LC-MS/MS and GC-MS Identification of Metabolites from the Selected Herbs and Spices, Their Antioxidant, Anti-Diabetic Potential, and Chemometric Analysis
Hafiza Sehrish Kiani, Baber Ali, Mohammad Khalid Al-Sadoon, Hamad S. Al-Otaibi, Akhtar Ali
February 10, 2024 (v1)
Keywords: antioxidants, diabetes, drug discovery, flavonoids, herbs, human health, phytochemicals, spices, volatile compounds
Culinary herbs and spices are widely used in daily diets. Pakistan’s flora is enriched with phytochemicals due to a diverse range of land. Phytochemicals, including volatile and non-volatile compounds, have captured much interest due to their numerous health advantages and significance in daily diet. The present study aimed to conduct in-depth metabolomic profiling of Pakistani-grown fenugreek leaves (Trigonella foenum-graecum), fennel seeds (Foeniculum vulgare), mint leaves (Mentha royleana), coriander seeds (Coriandrum sativum) and basil leaves (Ocimum basilicum) by using liquid chromatography−mass spectrometry (LC-MS/MS) and gas chromatography−mass spectrometry (GC-MS). The first study was conducted to optimize extraction using different solvents (methanol, ethanol, chloroform, acetone, and water). Total phenolic content (TPC), total flavonoid content (TFC), and total condensed tannins (TCT) were quantified along with the antioxidant and anti-diabetic activities. The highest TPC (12... [more]
Microbial Population Dynamics during Unstable Operation of a Semicontinuous Anaerobic Digester Fed with a Mild-Treated Olive Mill Solid Waste
Juan Cubero-Cardoso, África Fernández-Prior, Javier Ramiro-Garcia, Angeles Trujillo-Reyes, Belén Caballero-Guerrero, Guillermo Rodríguez-Gutiérrez, Fernando G. Fermoso
February 10, 2024 (v1)
Subject: Biosystems
Keywords: anaerobic digestion, phenol, solid waste, thermal treatment, valorization
This research evaluates process instability together with microbial population dynamics of the startup of an anaerobic digestion of a mild pretreated solid olive oil waste. The pretreatment consisted of a mild thermal treatment called thermo-malaxation and a subsequent dephenolized process of the olive mill solid waste. The anaerobic digestion process of the mild pretreated and partially dephenolized biomass was studied for three Hydraulic Retention Times (HRTs), with 21 days each HRT, with an organic load rate of 1 g VS/L d, carried out at mesophilic temperature (35 ± 1 °C). The average value of methane yield decreased from 204 ± 9 mL CH4/g VS d on day 21, the last day of the first HRT, to 87 ± 24 mL CH4/g VS d on day 60, the last day of the third HRT. The alkalinity decreased drastically, indicating instability of the anaerobic digestion process. Although phenolic compounds were partially extracted in the pretreatment, the observed increase in phenolic compounds during reactor operat... [more]
Reducing the Environmental and Economic Consequences of Installing an Underground Collector and Increasing User Comfort with a New Geometry and Installation Method
Ľubomíra Gabániová, Dušan Kudelas
February 10, 2024 (v1)
Keywords: Computational Fluid Dynamics, ground collector, heat extraction, renewable energy sources
The installation of ground collectors often has several disadvantages for the user, despite future benefits in more ecological heating, namely the need for a large space for installation, which increases costs, and can also cause inconvenience later, for example, by keeping snow on the surface for a longer time. The goal of this paper was to find out with the help of simulations in ANSYS whether a collector with a different geometry and arrangement (vertical spiral with diameters of 6, 8 and 10 m), which would be more comfortable, cheaper, and also friendlier to the environment, would achieve performance similar to the classic geometry—meander. The initial results are relatively favorable and prove that there is room for optimization and improvement in this field. Verification of network sensitivity in all cases is 8% or less. In the current situation of the energy crisis, it is necessary to look for the possibilities of using heat pumps in cities and metropolises. The new geometry cou... [more]
Coal and Gas Outburst Prediction Model Based on Miceforest Filling and PHHO−KELM
Liangshan Shao, Wenjing Chen
February 10, 2024 (v1)
Subject: Optimization
Keywords: coal and gas outburst prediction, Harris Hawk optimization algorithm with Piecewise chaotic mapping, kernel extreme learning machine, missing data filling, multiple filling of chained equations for random forests
Coal and gas outbursts are some of the most serious coal mine disasters, and effective prediction of coal and gas outbursts can reduce the likelihood of accidents and fatalities. Previously conducted studies have established that machine learning has achieved results in the prediction of coal and gas outbursts, but there is a problem that the available accident data of coal and gas outbursts are diminished or missing. This paper proposes a prediction model based on multiple filling of chained equations for random forests (miceforest) and the Harris Hawk optimization algorithm with Piecewise chaos mapping (PHHO) to optimize the kernel extreme learning machine (KELM) to solve the problem of missing data in coal and gas outburst prediction and to improve prediction accuracy in the case of missing data. Firstly, the miceforest algorithm was adopted to fill missing values in the salient samples, and then the PHHO algorithm was used to optimize the parameters of KELM. Finally, the datasets b... [more]
The Adhesion Strength of Semi-Clathrate Hydrate to Different Solid Surfaces
Zhen Xu, Lei Zheng, Zhen Dong, Aixian Liu, Yiwei Wang, Qiang Sun, Jianyi Chen, Xuqiang Guo
February 10, 2024 (v1)
Subject: Materials
Keywords: adhesion strength, hydrate, subcooling, surface roughness, surface wettability
The adhesion between a hydrate and a pipe wall is the main cause of hydrate deposition and blockage. In this study, the adhesion strength of semi-clathrate hydrate (tetrabutylammonium bromide hydrate) to four kinds of solid surfaces (E235B carbon steel, E355CC low alloy steel, SUS304 stainless steel, and polytetrafluoroethylene) was measured. This investigation reveals that the adhesion strength of the hydrate to a solid surface is negatively correlated with the wettability of the solid surface, which suggests that hydrophobic materials effectively reduced the hydrate adhesion to the pipe wall. The surface roughness showed different effects on the adhesion of the hydrate to hydrophilic or hydrophobic surfaces. To be specific, when the surface roughness increased from 3.2 µm to 12.5 µm, the hydrate adhesion strength to the hydrophilic surface of SUS304 increased by 123.6%, whereas the hydrate adhesion strength to the hydrophobic surface of polytetrafluoroethylene only increased by 21.5%... [more]
Methods of Partial Differential Equation Discovery: Application to Experimental Data on Heat Transfer Problem
Tatiana A. Andreeva, Nikolay Y. Bykov, Yakov A. Gataulin, Alexander A. Hvatov, Alexandra K. Klimova, Alexander Ya. Lukin, Mikhail A. Maslyaev
February 10, 2024 (v1)
Keywords: best subset selection, data-driven models, discovering partial differential equations, genetic evolutionary algorithm, heat transfer equation, inverse problems, submerged horizontal cylindrical heat source, viscous liquid convection
The paper presents two effective methods for discovering process models in the form of partial differential equations based on an evolutionary algorithm and an algorithm for the best subset selection. The methods are designed to work with sparse and noisy data and implement various numerical differentiation techniques, including piecewise local approximation using multidimensional polynomial functions, neural network approximation, and an additional algorithm for selecting differentiation steps. To verify the algorithms, the experiment is carried out on pulsed heating of a viscous liquid (glycerol) by a submerged horizontal cylindrical heat source. Temperature measurements are taken only at six points, which makes the data very sparse. The noise level ranges from 0.2 to 1% of the observed maximum temperature. The algorithms can successfully restore the structure of the heat transfer equation in cylindrical coordinates and determine the thermal diffusivity coefficient with an error of 2... [more]
Enhancing Bioactive Compound Bioaccessibility in Tapirira guianensis Juices through Ultrasound-Assisted Applications
Josiana Moreira Mar, Renilto Frota Corrêa, Andrezza da Silva Ramos, Valdely Ferreira Kinupp, Edgar Aparecido Sanches, Pedro Henrique Campelo, Jaqueline de Araújo Bezerra
February 10, 2024 (v1)
Subject: Biosystems
Keywords: “pau-pombo”, Anacardiaceae, compounds phenolics, flavonols, galloylquinic acids
This study evaluated the chemical profile and bioactive compounds in Tapirira guianensis juice samples under high-intensity ultrasound (US) effects. T. guianensis juices were produced and processed using the US with varying ultrasound energy (0, 0.9, 1.8, 2.7, and 3.6 kJ·cm−3) for 10 min. The treated juices were evaluated for total acidity, color, pH, total phenolic compounds, anthocyanins, carotenoids, antioxidant capacity, in vitro digestibility, as well as quantification of bioactive compounds by HPLC-DAD. The hydromethanolic extract obtained from T. guianensis exhibited the presence of two major categories of polyphenols, specifically galloylquinic acids and flavonols. Overall, US technology was responsible for inducing some negative changes, such as carotenoid degradation, but also some positive changes in the chemical profile of the beverages, such as increased phenolic content, improved antioxidant capacity, and increased anthocyanin content. However, the beneficial effects were... [more]
Redox Performance and Optimization of the Chemical Composition of Lanthanum−Strontium−Manganese-Based Perovskite Oxide for Two-Step Thermochemical CO2 Splitting
Hiroki Sawaguri, Daichi Yasuhara, Nobuyuki Gokon
February 10, 2024 (v1)
Subject: Optimization
Keywords: CO2 splitting, concentrated solar radiation, perovskite oxide, redox oxides, solar fuel, thermal stability, thermochemical cycle, X-ray photoelectron spectroscopy
The effects of substitution at the A- and B sites on the redox performance of a series of lanthanum−strontium−manganese (LSM)-based perovskite oxides (Z = Ni, Co, and Mg) were studied for application in a two-step thermochemical CO2 splitting cycle to produce liquid fuel from synthesis gas using concentrated solar radiation as the proposed energy source and CO2 recovered from the atmosphere as the prospective chemical source. The redox reactivity, stoichiometry of oxygen/CO production, and optimum chemical composition of Ni-, Co-, and Mg-substituted LSM perovskites were investigated to enhance oxygen/CO productivity. Furthermore, the long-term thermal stabilities and thermochemical repeatabilities of the oxides were evaluated and compared with previous data. The valence changes in the constituent ionic species of the perovskite oxides were studied and evaluated by X-ray photoelectron spectroscopy (XPS) for each step of the thermochemical cycle. From the perspectives of high redox react... [more]
Optimization Method for Hot Air Reflow Soldering Process Based on Robust Design
Linjie Ran, Dong Chen, Cai Chen, Yubing Gong
February 10, 2024 (v1)
Keywords: process design, reflow soldering, robust optimization, Surrogate Model
The process design of hot air reflow soldering is one of the key factors affecting the quality of PCBA (Printed Circuit Board Assembly) component products. In order to improve the product quality during the design process, this paper proposes a robust optimization-based finite element simulation analysis method including significant influencing factor screening, robustness evaluation, robust optimization, and reliability verification for the reflow soldering process. The simulation model of the reflow soldering process temperature field based on experiments is constructed and validated. Sensitivity analysis is used to select important influencing factors, such as the last five set temperature zones (T5 to T9) in the reflow oven and the thermal properties of materials such as PCBs (printed circuit boards), BGAs (ball grid arrays), and solder paste, as well as noise factors like the heating environment during the soldering process. Several surrogate models are used to construct the respo... [more]
Design and Simulation of a Feedback Controller for an Active Suspension System: A Simplified Approach
Vasileios Provatas, Dimitris Ipsakis
February 10, 2024 (v1)
Keywords: active car suspension, controller performance criteria, model-based controller, modeling and simulation, optimal PID, PID controller, tuning methods
The concept of controlling vehicle comfort is a common problem that is faced in most under- and postgraduate courses in Engineering Schools. The aim of this study is to provide a simplified approach for the feedback control design and simulation of active suspension systems, which are applied in vehicles. Firstly, the mathematical model of an active suspension system (a quarter model of a car) which consists of a passive spring, a passive damper and an actuator is provided. In this study, we chose to design and compare the following controllers: (a) conventional P, PI and PID controllers that were tuned through two conventional methodologies (Ziegler−Nichols and Tyreus−Luyben); (b) an optimal PID controller that was tuned with a genetic algorithm (GA) optimization framework in terms of the minimization of certain performance criteria and (c) an internal model controller (IMC) based on the process transfer function. The controllers’ performance was assessed in a series of realistic scen... [more]
Quantitative Analysis of Soil Cd Content Based on the Fusion of Vis-NIR and XRF Spectral Data in the Impacted Area of a Metallurgical Slag Site in Gejiu, Yunnan
Zhenlong Zhang, Zhe Wang, Ying Luo, Jiaqian Zhang, Xiyang Feng, Qiuping Zeng, Duan Tian, Chao Li, Yongde Zhang, Yuping Wang, Shu Chen, Li Chen
February 10, 2024 (v1)
Subject: Environment
Keywords: competitive adaptive reweighted sampling, soil Cd pollution, spectral fusion, visible-near infrared, X-ray fluorescence
Vis-NIR and XRF spectroscopy are widely used in monitoring heavy metals in soil due to their advantages of being fast, non-destructive, cost-effective, and non-polluting. However, when used individually, XRF and vis-NIR may not meet the accuracy requirements for Cd determination. In this study, we focused on the impact area of a non-ferrous metal smelting slag site in Gejiu City, Yunnan Province, fused the pre-selected vis-NIR and XRF spectra using the Pearson correlation coefficient (PCC), and identified the characteristic spectra using the competitive adaptive reweighted sampling (CARS) method. Based on this, a quantitative model for soil Cd concentration was established using partial least squares regression (PLSR). The results showed that among the four fusion spectral quantitative models constructed, the model combining vis-NIR spectral second-order derivative transformation and XRF spectral first-order derivative transformation (D2(vis-NIR) + D1(XRF)) had the highest coefficient... [more]
A Tabu-Matching Heuristic Algorithm Based on Temperature Feasibility for Efficient Synthesis of Heat Exchanger Networks
Xiaohuang Huang, Hao Shen, Wenhao Yue, Huanhuan Duan, Guomin Cui
February 10, 2024 (v1)
Keywords: Heat Exchanger Network, heuristic method, tabu matching, temperature interval
The non-structural model of heat exchanger networks (HENs) offers a wide solution space for optimization due to the random matching of hot and cold streams. However, this stochastic matching can sometimes result in infeasible structures, leading to inefficient optimization. To address this issue, a tabu matching based on a heuristic algorithm for HENs is proposed. The proposed tabu-matching method involves three main steps: First, the critical temperature levels—high, medium, and low-temperature intervals—are determined based on the inlet and outlet temperatures of streams. Second, the number of nodes is set according to the temperature intervals. Third, the nodes of streams are flexibly matched within the tabu rules: the low-temperature interval of hot streams with the high-temperature interval of cold streams; the streams crossing cannot be matched. The results revealed that by incorporating the tabu rules and adjusting the number of nodes, the ratio of the feasible zone in the whole... [more]
Showing records 74 to 98 of 263. [First] Page: 1 2 3 4 5 6 7 8 Last