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Influence of curing conditions on the shrinkage behavior of three-dimensional printed concrete formwork

Frontiers of structural and Civil Engineering 2024年第8期18卷 1225-1236页

作者： m.BEKAERT K.van TITTELBOOm G.de sCHUTTER magnel-Vandepitte Laboratory for structural Engineering and Building materials Department of Structural Engineering and Building MaterialsFaculty of Engineering and ArchitectureGhent UniversityGhent 60 B-9052Belgium

The use of three-dimensional(3d)printed concrete as formwork is becoming more widely applied within the ***,the technology is still not optimized and there are many reports of preliminary cracking during the curing of cast *** is believed to result from differential shrinkage between the printed and cast *** cracks(in the printed concrete or at the interface between the infill and printed concrete)form a preferential path for aggressive substances and can reduce the durability of the combined concrete *** ensure the desired service life of the structure,it is important that the differential shrinkage between cast and printed concrete is *** study investigated the effect of curing conditions on the differential shrinkage behavior of 3d and cast *** influence of prewetting of the dry-cured 3d printed formwork was also *** the experimental program,a vibrated and self-compacting concrete were used as cast *** 3d printed formwork was produced and combined with cast concrete to simulate a concrete *** formwork was cured for 1,7,or 28 d exposed to the air(relative humidity:60%or 95%)or submerged in *** length change of the combined elements was observed over 56 d after concrete casting and throughout the thickness of the *** show that increasing the curing period in dry conditions of the printed concrete leads to an expansion of the formwork on the first day after *** expansion leads to a non-uniform strain evolution throughout the curing period of the combined *** concrete formwork stored in wet conditions does not expand after the casting process but tends to show a decreasing linear deformation within the whole elements.

关键词： 3d concrete printing formwork shrinkage curing

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Fast prediction of rain erosion in wind turbine blades using a data-based computational tool

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Journal of Hydrodynamics 2024年第3期36卷 504-518页

作者： Juan m.Gimenez sergio R.Idelsohn Eugenio Oñate Centre Internacional de mètodes Numèrics en Enginyeria(CImNE) Edifici C1 Campus Nord UPC C/Gran CapitàS/NBarcelonaSpain

Wind turbines(WTs)face a high risk of failure due to environmental factors like erosion,particularly in high-precipitation areas and offshore *** this paper we introduce a novel computational tool for the fast prediction of rain erosion damage on WT blades that is useful in operation and maintenance decision making *** approach is as follows:Pseudo-direct Numerical simulation(P-dNs)simulations of the droplet-laden flow around the blade section profile are employed to build a high-fidelity da.a.set of impact statistics for potential operating *** this database as training data,a machine learning-based surrogate model provides the feature of the impact pattern over the 2-d section for given wind and rain *** this information,a fatigue-based model estimates the remaining lifetime and erosion damage for both homogeneous and coating-substrate blade *** prediction is done by quantifying the accumulated droplet impact energy and evaluating operative conditions over time periods for which the weather at the installation site is *** this work,we describe the modules that compose the prediction method,namely the database creation,the training of the surrogate model and their coupling to build the prediction ***,the method is applied to predict the remaining lifetime and erosion damage to the blade sections of a reference *** evaluate the reliability of the tool,several site locations(offshore,coastal,and inland),the coating material and the coating thickness of the blade are *** few minutes we are able to estimate erosion after many years of *** results are in good agreement with field observations,showing the promise of the new rain erosion prediction approach.

关键词： Wind turbine blades leading edge erosion fatigue Pseudo-direct Numerical simulation(P-dNs) machine learning eblader

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A hierarchical multi-UAV cooperative framework for infrastructure inspection and reconstruction

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Control Theory and Technology 2024年第3期22卷 394-405页

作者： Chuanxiang Gao Xinyi Wang Xi Chen Ben m.Chen department of mechanical and Automation Engineering The Chinese University of Hong KongHong KongShatinNTChina

Unmanned aerial vehicles(UAVs)are emerging as a powerful tool for inspections and repair works in large-scale and unstructured 3d infrastructures,but current approaches take a long time to cover the entire *** using UAVs for inspections and repair works puts forward a requirement of improving time efficiency in large-scale and cluster *** paper presents a hierarchical multi-UAV cooperative framework for infrastructure inspection and reconstruction to balance the workload and reduce the overall task completion *** proposed framework consists of two stages,the exploration stage and the exploitation stage,resolving the task in a sequential *** the exploration stage,the density map is developed to update global and local information for dynamic load-balanced area partition based on reconstructability and relative positions of UAVs,and the Voronoi-based planner is used to enable the UAVs to reach their best *** obtaining the global map,viewpoints are generated and divided while taking into account the battery capacity of each ***,a shortest path planning method is used to minimize the total traveling cost of these viewpoints for obtaining a high-quality *** experiments are conducted in both a simulated and real environment to show the time efficiency,robustness,and effectiveness of the proposed ***,the whole system is implemented in real applications.

关键词： multi-UAV Coverage path planning Infrastructure inspection and reconstruction

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Electrodeless plasma thrusters for spacecraft: a review

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Plasma science and Technology 2017年第8期19卷 1-24页

作者： s N BATHGATE m m m BILEK d R mCKENZIE Applied and Plasma Physics School of PhysicsUniversity of Sydney

The physics of electrodeless electric thrusters that use directed plasma to propel spacecraft without employing electrodes subject to plasma erosion is reviewed. Electrodeless plasma thrusters are potentially more durable than presently deployed thrusters that use electrodes such as gridded ion,Hall thrusters, arcjets and resistojets. Like other plasma thrusters, electrodeless thrusters have the advantage of reduced fuel mass compared to chemical thrusters that produce the same thrust. The status of electrodeless plasma thrusters that could be used in communications satellites and in spacecraft for interplanetary missions is examined. Electrodeless thrusters under development or planned for deployment include devices that use a rotating magnetic field; devices that use a rotating electric field; pulsed inductive devices that exploit the Lorentz force on an induced current loop in a plasma; devices that use radiofrequency fields to heat plasmas and have magnetic nozzles to accelerate the hot plasma and other devices that exploit the Lorentz force. Using metrics of specific impulse and thrust efficiency, we find that the most promising designs are those that use Lorentz forces directly to expel plasma and those that use magnetic nozzles to accelerate plasma.

关键词： spacecraft a review propellant Lorentz thrust rotating radiofrequency erosion presently exploit

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Earthquake response of asymmetric building with mR damper

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Earthquake Engineering and Engineering Vibration 2014年第2期13卷 305-316页

作者： s.d.Bhart s.m.dumne m.K.shrimali department of Civil Engineering malaviya National Institute of Technology Jaipur Govt.Poly.College Nashik Maharashtra India

Plan asymmetric buildings are very susceptible to earthquake induced damage due to lateral torsional coupling, and the corners of these systems suffer heavy damage during earthquakes. Therefore, it is important to investigate the seismic behavior of an asymmetric plan building with mR dampers. In this study, the effectiveness of mR damper-based control systems has been investigated for seismic hazard mitigation of a plan asymmetric building. Furthermore, the infl uence of the building parameters and damper command voltage on the control performance is examined through parametric study. The building parameters chosen are eccentricity ratio and frequency ratio. The results show that the mR damper-based control systems are effective for plan asymmetric systems.

关键词： torsional coupling plan asymmetric mR damper

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Large scale silver nanowires network fabricated by meV hydrogen (H＋) ion beam irradiation

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Chinese Physics B 2016年第4期25卷 268-273页

作者： Honey s Naseem s Ishaq A maaza m Bhatti m T Wan d Center of Excellence in solid state Physics University of the Punjab Lahore Pakistan National Center for Physics Quaid-i-Azam University Islamabad 44000 Pakistan UNEsCO-UNIsA Africa Chair in Nanosciences/Nanotechnology College of Graduate Studies University of South Africa Muckleneuk ridge P. O. Box 392 Pretoria South Africa Nanosciences African Network (NANOAFNET) iThemba LABS National Research Foundation Old Faure road P. O. Box 722 Somerset West 7129 South Africa department of Physics Bahauddin Zakariya University Multan 60800 Pakistan school of materials science and Engineering Shanghai University Shanghai 201900 China

A random two-dimensional large scale nano-network of silver nanowires （Ag-NWs） is fabricated by meV hydrogen （H＋） ion beam irradiation. Ag-NWs are irradiated under H＋ ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H＋ ion beam-induced welding of Ag-NWs at intersecting positions. H＋ ion beam induced welding is confirmed by transmission electron microscopy （TEm） and scanning electron microscopy （sEm）. moreover, the structure of Ag NWs remains stable under H＋ ion beam, and networks are optically transparent. morphology also remains stable under H＋ ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under meV H＋ ion beam irradiation. The results exhibit that the formation of Ag-NW network proceeds through three steps： ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from meV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices.

关键词： Ag nanowires H+ ion irradiation nanowelding large scale nano-network optical properties

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sensory Phenotypic and molecular Identification of Aromatic Rice Accessions Cultivated in Benin

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Advances in Bioscience and Biotechnology 2024年第3期15卷 195-206页

作者： Chimène Nadège mahoussi Nanoukon Koffi david montcho Hambada deless Edmond Fulgence Thiémélé Bignon meyrix Pamela Franzel Loumedjinon Babatoundé Franel Carel Wenceslas Affolabi Amed sèmèvo Havivi Kéllya Laurinzo déguénon Grâce Finagnon Vitoekpon Arielle Bankole Lambert Gustave djedatin Laboratory of molecular Biology and Bioinformatics Applied to Genomics National School of Applied Biosciences and Bio-technologies National University of Science Technology Engineering and Mathematics Dassa-Zoumè Benin Laboratory of molecular Biology and Bioinformatics Applied to Genomics National School of Applied Biosciences and Biotechnologies National University of Science Technology Engineering and Mathematics Dassa-Zoumè Benin Laboratory of Plant Horticultural and Forestry Sciences National University of Agriculture Kétou Benin Genetics Teaching and Research Unit Department of Biochemistry-Genetics Peleforo GON COULIBALY University Korhogo C&#244te d’Ivoire

Rice is one of the most widely cultivated cereals in the world, and its aroma is increasingly in demand. With the advancement of research, a major rice flavor gene has been identified on rice chromosome 8. It encodes non-functional betaine aldehyde dehydrogenase leading to the accumulation of 2-acetyl-1-pyrroline which is the major olfactory compound that confers the fragrant character to rice. The aroma of rice is considered a special trait of enormous economic importance that determines the prime price in world trade. To satisfy the needs of the population and reduce rice imports into Benin, we conducted this study to identify aromatic rice accessions grown in Benin. seventy-two rice accessions collected across Benin were PCR amplified with three ssR markers Rm 7049, Aro 7, and Rm 223, linked to the fgr (fragrance of rice) aroma gene. molecular analysis revealed that 12 of the 72 accessions, namely Bagou 19, Bagou 22, Tchaka 34, Foun 15, Tchaka 41, Nana 32, Kan 61, Kung 69, Kung 67, Bagou 20, Agbab 101 and Koum 55 possess the fgr gene and can be considered as aromatic rice accessions. A sensory phenotypic test using KOH was carried out on rice accessions carrying fgr gene. Of the twelve positives, only one had the smell of aromatic rice, like the Azucena control. These results show that Benin also has aromatic rice varieties that can be sold on national and international markets.

关键词： Aromatic Rice 2-Acetyl-1-Pyrroline ssR markers Benin

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modulation of oxidative damage and genotoxicity of biosynthesized zinc oxide nanoparticles via supplementation with modified cinnamaldehyde-loaded chitosan nanoparticles in mice

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Food science and Human Wellness 2024年

作者： mosaad A.Abdel-Wahhab Aziza A.El-Nekeety Asmaa s.salman Zeinab K.Hamza Engy m.Akl soher E.Aly Wenyi Kang department of Food Toxicology & Contaminants， National Research Centre Dokki， Cairo， Egypt Genetic and Cytology department， National Research Centre Dokki， Cairo， Egypt department of Fats and Oils， National Research Centre Dokki， Cairo， Egypt National R & d Center for Edible Fungus Processing Technology， Henan University Joint International Research Laboratory of Food & medicine Resource Function Functional Food Engineering Technology Research Center Henan

synthesis of zinc oxide nanoparticles (Zn-NPs) via green method is an outstanding alternative to conventional/regular methods; however， the safety or toxicity of the biosynthesized ZnO-NPs in vivo is not fully explored. This study was conducted to evaluate the protective efficiency of cinnamaldehyde-loaded chitosan nanoparticles (Cin@CsNPs) against oxidative damage and genotoxicity of zinc oxide nanoparticles (ZnO-NPs) in mice. ZnO-NPs were biosynthesized using the extract of fresh leaves of mentha pulegium L. Cin was extracted from cinnamon essential oil， and was loaded into chitosan nanoparticle (Cin@CsNPs). Both ZnO-NPs， Cin@CsNPs and CsNPs were characterized. The in vitro release of Cin@CsNPs was determined. In the biological study， 6 groups of male Balb/c mice were treated by gavage for 3 weeks as follows， control group， the group received ZnO-NPs (25 mg/kg b.w)， the groups received Cin@CsNPs at low dose (50 mg/kg b.w) or high dose (100 mg/kg b.w)， and the groups received ZnO-NPs plus Cin@CsNPs at the two tested doses. Blood and tissue samples were collected for different biochemical， genetical and histological studies. The particle size of ZnO-NPs， CsNPs， and Cin@CsNPs were (20.78 ± 2.6)， (170.0 ± 3.7)， and (218.23 ± 2.9) nm， and ξ-potential were (32.7 ± 4.6)， (8.32 ± 0.27) and (4.8 ± 0.21)， respectively. ZnO-NPs disturbed the biochemical and oxidative stress indices， AFP， CEA， TNF-α， chromosomal aberrations in somatic and germ cells， and sperm abnormality along with severe pathological changes in the hepatic， renal， and testicular tissues. Cin@CsNPs improved significantly all the parameters tested and the histological picture in a dose-dependent. Therefore， the biosynthesized ZnO-NPs exhibit oxidative damage and genotoxicity， and Cin@CsNPs have potential protective effects against the risks of ZnO-NPs and may be a promising tool to overcome the challenges of using Cin in food and pharmaceuticals applications.

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Analysis of turbulent mHd Couette nanofluid flow and heat transfer using hybrid dTm-Fdm

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Particuology 2016年第3期14卷 95-101页

作者： s. mosayebidorcheh m. sheikholeslami m. Hatami d.d. Ganji Young Researchers and Elite Club Najafabad Branch lslamicAzad University Ndjafabad Iran department of mechanical Engineering Lenjan Branch Islamic Azad University lsfahan Iron department of mechanical Engineering Babol University of Technology Babol Iran mechanical Engineering department Engineering and Technical College Esfarayen University Esfarayen North Khorasan lran

Unsteady turbulent magnetohydrodynamic nanofluid hydrothermal treatment is studied. The zero- equation turbulence model is used to simulate turbulent flow. The modeling results obtained by applying the hybrid differential transformation method-finite difference method to solve this problem confirm its viability. An analytical procedure is used for finding the effects of the problem parameters. Results indicate that the average Nusselt number over the lower plate depends linearly on volume fraction of nanofluid, Hall parameter, turbulent Eckert number, and Reynolds number whereas it is inversely proportional on the Hartmann number and the turbulent parameter.

关键词： Turbulent Hall effect Hybrid dTm-Fdm Nanofluid magnetohydrodynarnic couette flow

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solution of nonlinear cubic-quintic duffing oscillators using He’s Energy Balance method

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Journal of Zhejiang University-science A(Applied Physics & Engineering) 2009年第9期10卷 1263-1268页

作者： d.d.GANJI m.GORJI s.sOLEImANI m.EsmAEILPOUR department of mechanical Engineering University of Mazandaran

In this study, He＇s Energy Balance method （EBm） was applied to solve strong nonlinear duffing oscillators with cubic-quintic nonlinear restoring force. The complete EBm solution procedure of the cubic-quintic duffing oscillator equation is presented. For illustration of effectiveness and convenience of the EBm, different cases of cubic-quintic duffing oscillator with different parameters of α,β and y were compared with the exact solution. We found that the solutions were valid for small as well as large amplitudes of oscillation. The results show that the EBm is very convenient and precise, so it can be widely appli- cable in engineering and other sciences.

关键词： Energy Balance method (EBm) Cubic-quintic duffing equation Oscillator

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