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Effect of linear friction welding process on microstructure evolution,mechanical properties and corrosion behavior of GH4169 superalloy

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Chinese Journal of Aeronautics 2024年第6期37卷 504-520页

作者： Yu SU Xiawei YANG Tingxi MENG Dong WU Rui XU Haiyu XU Wenya LI Shuo YIN State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China department of Mechanical Manufacturing&Biomedical EngineeringParsons BuildingTrinity College DublinThe University of DublinDublin 2Ireland

Linear Friction Welding(LFW)technology was used to realize the welding of GH4169 superalloy,and the effect of welding parameters on the microstructure,mechanical properties and corrosion behavior of the joint was *** results show that there is a positive correlation between the weld hardness and the tensile *** the gradual increase of heat input and welding pressure,the joint quality is gradually improved,but the heat affected zone is not significantly *** smaller the grain size of the weld,the higher the strength and plasticity of the *** the increase of the joint shortening amount,the corrosion resistance of the weld first gradually ***,when the shortening reaches a certain level,the corrosion resistance of the joint becomes little *** the increase of solution temperature,the corrosion current density increases and the polarization impedance *** higher the corrosion temperature,the worse the corrosion resistance of the *** is no significant correlation between the joint strength and the corrosion *** corrosion resistance of the joint can be enhanced without changing the joint mechanical properties by reducing the welding frequency and amplitude or increasing the welding pressure.

关键词： Linear Friction Welding(LFW) GH4169 superalloy Microstructure Mechanical properties Corrosion behavior

Numerical investigation of the photo-thermal characteristics of a direct absorption solar collector using Monte Carlo and finite volume methods

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Science China(Technological Sciences) 2024年第8期67卷 2436-2448页

作者： ZHU YanLong LI SuNing FAN JianHua KONG WeiQiang YUAN Yuan TAN HePing School of Energy Science and engineering Harbin Institute of TechnologyHarbin 150001China department of Civil engineering and Mechanical engineering Technical University of DenmarkKoppels AlléBuilding 4042800 Kgs.LyngbyDenmark School of Vehicle and Energy Yanshan UniversityQinhuangdao 066004China

In this study, a novel model of photothermal conversion in a direct absorption solar collector based on the Monte Carlo and finite volume methods was built and validated and the temperatures of the novel and traditional solar collectors were compared. The sensitivity of the parameters to the radiative heat loss was investigated. Finally, the radiative heat transfer characteristics were discussed using the radiative exchange factor. The results of this study validated the advantages of the novel solar collector at both the surface and fluid temperatures. Under the conditions used in this study, the maximum temperature difference of the novel solar collector was 30 K, compared with 193 K for the traditional solar collector. Furthermore, the collector was divided into several units along the flow direction. The radiative exchange factor indicated that with an increase in the attenuation coefficient, the percentage of radiation intensity in the total solar radiation absorbed by the corresponding unit ***, it decreased with an increase in the incident angle and scattering albedo. These results provide a reference for addressing the low efficiency and thermal damage caused by traditional solar collectors at high temperatures.

关键词： direct absorption solar collector radiative heat transfer Monte Carlo

High-performance formaldehyde prediction for indoor air quality assessment using time series deep learning

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building Simulation 2024年第3期17卷 415-429页

作者： Liu Lu Xinyu Huang Xiaojun Zhou Junfei Guo Xiaohu Yang Jinyue Yan School of Human Settlements and Civil engineering Xi’an Jiaotong UniversityXi’anChina department of building Environment and Energy engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina Future Energy Profile School of BusinessSocietyand EngineeringMälardalen UniversityVästeråsSweden

Indoor air pollution resulting from volatile organic compounds(VOCs),especially formaldehyde,is a significant health concern needed to predict indoor formaldehyde concentration(Cf)in green intelligent building *** study develops a thermal and wet coupling calculation model of porous fabric to account for the migration of formaldehyde molecules in indoor air and cotton,silk,and polyester fabric with heat flux in Harbin,Beijing,Xi’an,Shanghai,Guangzhou,and Kunming,*** time-by-time indoor dry-bulb temperature(T),relative humidity(RH),and Cf,obtained from verified simulations,were collated and used as input data for the long short-term memory(LSTM)of the deep learning model that predicts indoor multivariate time series Cf from the secondary source effects of indoor fabrics(adsorption and release of formaldehyde).The trained LSTM model can be used to predict multivariate time series Cf at other emission times and *** LSTM-based model also predicted Cf with mean absolute percentage error(MAPE),symmetric mean absolute percentage error(SMAPE),mean absolute error(MAE),mean square error(MSE),and root mean square error(RMSE)that fell within 10%,10%,0.5,0.5,and 0.8,*** addition,the characteristics of the input dataset,model parameters,the prediction accuracy of different indoor fabrics,and the uncertainty of the data set are *** results show that the prediction accuracy of single data set input is higher than that of temperature and humidity input,and the prediction accuracy of LSTM is better than recurrent neural network(RNN).The method’s feasibility was established,and the study provides theoretical support for guiding indoor air pollution control measures and ensuring human health and safety.

关键词： multivariate time series formaldehyde concentration deep learning heat-humidity coupling mass transfer secondary source effect

An integrated computational method for calculating dynamic thermal bridges of building facades in tropical countries

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Frontiers of Architectural Research 2024年第1期13卷 201-218页

作者： Miktha Farid Alkadri Muhammad Rafif Cahyadi Agung Francesco De Luca Research Cluster of Architectural Sciences and building Technology Department of ArchitectureFaculty of EngineeringUniversitas IndonesiaDepok 16425Indonesia department of Civil engineering and Architecture Tallinn University of TechnologyTallinn 19086Estonia

Identifying thermal bridges on building façades has been a great challenge for architects,especially during the conceptual design *** is not only due to the complexity of parameters when calculating thermal bridges,but also lack of feature integration between building energy simulation(BES)tools and the actual building *** example,existing BES tools predominantly calculate thermal bridges only in steady state without considering the temperature dynamic behaviour of building ***,relevant features such as thermal delay,decrement factor,and operative temperature are often neglected,and this can lead to miscalculation of energy *** study then proposes an integrated method to calculate dynamic thermal bridges under transient conditions by incorporating field observations and computational simulations of thermal *** specifically,the proposed method employs several measurement tools such as HOBO data logger to record the actual conditions of indoor and outdoor room temperature and thermal cameras to identify the surface temperature of selected building *** actual datasets are then integrated with the simulation workflow developed in BES *** study ultimately enables architects not only to identify potential thermal bridges on existing building façades but also to support material and geometric exploration in early design phase.

关键词： Thermal bridges Dynamic calculation Thermal delay Cooling load Computational design method

In search of optimal building behavior models for model predictive control in the context of flexibility

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building Simulation 2024年第1期17卷 71-91页

作者： Arash Erfani Tohid Jafarinejad Staf Roels Dirk Saelens KU Leuven Department of Civil EngineeringBuilding Physics and Sustainable Design SectionKasteelpark Arenberg 40 Bus 24473001 HeverleeBelgium EnergyVille Thor Park 8310Genk 3600Belgium

Model predictive control(MPC)is an advanced control *** has been deployed to harness the energy flexibility of a *** requires a dynamic model of the building to achieve such an ***,developing a suitable predictive model is the main challenge in MPC implementation forflexibility *** studyfocuses on the application of key performance indicators(KPls)to evaluate the suitability of MPC models via feature *** this end,multiple models were developed for two houses.A feature selection method was developed to select an appropriate feature space to train the *** predictive models were then quantified based on one-step ahead prediction error(OSPE),a standard KPI used in multiple studies,and a less-often KPl:multi-step ahead prediction error(MSPE).An MPC workflow was designed where different models can serve as the predictive *** showed that MSPE better demonstrates the performance of predictive models used for flexibility *** revealed that up to 57% of the flexibility potential and 48% of energy use reduction are not exploited if MSPE is not minimized while developing a predictive model.

关键词： building flexibility model predictive control for building building behaviour identification smart home

Comparison of models to predict air infiltration rate of buildings with different surrounding environments

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building Simulation 2024年第6期17卷 1007-1021页

作者： Shu Zheng Xiujiao Song Lin Duanmu Yu Xue Xudong Yang department of building Science Tsinghua UniversityBeijing100084China School of Civil engineering Dalian University of TechnologyDalian116024China Shanxi Research Institute for Clean Energy Tsinghua UniversityTaiyuan030032China

The air infiltration rate of buildings strongly influences indoor environment and energy *** this study,several traditional methods for determining the air infiltration rate were compared,and their accuracy in different scenarios was ***,a method combining computational flow dynamics(CFD)with the Swami and Chandra(S-C)model was developed to predict the influence of the surrounding environment on the air infiltration *** buildings in Dalian,China,were selected:one with a simple surrounding environment and the other with a complex surrounding environment;their air infiltration rates were *** test results were used to validate the accuracy of the air infiltration rate solution models in different urban *** the building with a simple environment,the difference between the simulation and experimental results was 0.86%–22.52%.For the building with a complex environment,this difference ranged from 17.42%to 159.28%.We found that most traditional models provide accurate results for buildings with simple surrounding and that the simulation results widely vary for buildings with complex *** results of the method of combining CFD with the S-C model were more accurate,and the relative error between the simulation and test results was 10.61%.The results indicate that the environment around the building should be fully considered when calculating the air infiltration *** results of this study can guide the application of methods of determining air infiltration rate.

关键词： air infiltration rate models CFD simulation building surrounding air infiltration rate test

Hierarchical CoFe@N-Doped Carbon Decorated Wood Carbon as Bifunctional Cathode in Wearable Zn-Air Battery

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Energy & Environmental Materials 2024年第1期7卷 46-54页

作者： Kelong Ao Xiangyang Zhang Renat R.Nazmutdinov Di Wang Jihong Shi Xian Yue Jianguo Sun Wolfgang Schmickler Walid A.Daoud department of Mechanical engineering City University of Hong Kong Kazan National Research Technological University School of Textile and Garment Anhui Polytechnic University Wood Materials Science Institute for Building MaterialsETH Z èurich

Rechargeable Zn-air batteries(ZAB) have drawn extensive attention due to their eco-friendliness and ***,the lack of high-performance and low-cost oxygen redox reactions(OER and ORR) catalysts has become one of the main stumbling blocks in their ***,we successfully fabricate a CoFe nanobubble encapsulated in nitrogen-doped carbon nanocage on wood carbon support(CoFe@NC/WC) via pyrolysis of a novel Prussian blue analog(PBA)/spruce precursor.

关键词： biomass-based catalyst DFT computation hydrogel electrolyte oxygen redox reactions wearable Zn-air battery

Hydroxyl radical production by abiotic oxidation of pyrite under estuarine conditions:The effects of aging,seawater anions and illumination

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Journal of Environmental Sciences 2024年第1期135卷 715-727页

作者： Ruixue Liu Yinshun Dai Yucheng Feng Shiwen Sun Xiaodong Zhang Chunjiang An Shan Zhao Shandong Key Laboratory of Water Pollution Control and Resource Reuse School of Environmental Science and EngineeringShandong UniversityQingdao 266237China department of building Civil and Environmental EngineeringConcordia UniversityMontrealQC H3G 1M8Canada

Pyrite is widely distributed in estuarine sediments as an inexpensive natural Fenton-like reagent,however,the mechanism on the hydroxyl radical(HO^(·))production by pyrite under estuarine environmental conditions is still poorly *** batch experiments were performed to investigate the effects of estuarine conditions including aging(in air,in water),seawater anions(Cl^(-),Br^(-)and HCO_(3)^(-))and light on the HO^(·)production by pyrite *** one-electron transfer dominated the process from O_(2) to HO^(·)induced by oxidation of *** Fe(oxyhydr)oxide coatings on the surface of pyrite aged in air and water consumed hydrogen peroxide while mediating the electron transfer,and the combined effect of the two resulted in a suppression of HO^(·)production in the early stage of aging and a promotion of HO^(·)production in the later stage of *** of the surface oxide layers by aggressive anions was the main reason for the inhibition of HO^(·)production by Cl^(-)and Br^(-),and the generation of Cl^(·)and Br^(·)may also play a role in the scavenging of HO^(·).HCO_(3)^(-)increased the average rate of HO^(·)production through surface-CO_(2) complexes formed by adsorption on the surface of *** significant enhancement of HO^(·)production under light was attributed to the formation of photoelectrons induced by photochemical reactions on pyrite and its surface oxide *** findings provide new insights into the environmental chemical behavior of pyrite in the estuary and enrich the understanding of natural remediation of estuarine environments.

关键词： Hydroxyl radical Pyrite oxidation Aging Anions Irradiation

Evolution of inclusions in vacuum induction melting of superalloys containing 70%return material

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Journal of Iron and Steel Research International 2024年第3期31卷 719-728页

作者： Jin-guo Gao Shu-lei Yang Shu-feng Yang Jing-she Li Wei Liu Meng-jing Zhao An-ren Wang School of Metallurgical and Ecological engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Metallurgical and building Materials Business department China International Engineering Consulting CorporationBeijing 100048China

The variation law of inclusions type and size in the vacuum induction melting process and ingot of Ni-based superalloy containing 70%return material was studied by industrial test sampling,and the mechanism of inclusions formation was analyzed with thermodynamic *** results show that there are mainly two types of composite inclusions in the vacuum induction melting of Ni-based superalloys,which are nitride-and oxide-based composite inclusions,like Al_(2)O_(3)-SiO_(2)-Cr_(2)O_(3),TiN-(Mo,Nb)C,*** type and proportion of inclusions from the center to the edge of the vacuum induction ingot did not change *** number density of inclusions from the center to the edge of the ingot varied less,and the size of inclusions became smaller from the center to the *** addition,thermodynamic calculations show that oxides(M_(2)O_(3))are present in the liquid phase and mainly contain Al,Ti,Cr,Fe and O *** nitride consists mainly of Ti and N and contains small amounts of Cr,C,Nb,and Mo *** is consistent with the results of industrial *** the temperature decreases,the precipitation phases such as M_(2)O_(3),MN,γ,MC,δ,γ'andμphases are gradually precipitated,where oxides and nitrides are present in the liquid *** contents of O and N elements are the main influencing factors for the inclusions content and precipitation temperature;when the nitrogen content is reduced to below 0.0015%,it can make MN precipitate below the liquid-phase line.

关键词： Ni-based superalloy Vacuum induction melting Return material Inclusion Thermodynamic