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Energy absorption behaviors of a novel buffer lander-leg with Yoshimura core

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Chinese Journal of Aeronautics 2024年第4期37卷 333-342页

作者： Yan XU He HUANG Chao ZHANG Rongji FU school of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310027China school of Mechanics Civil Engineering and architecture Northwestern Polytechnical UniversityXi’an 710072China

In the current soft-landing system,the lander-leg and the buffer are two independent parts which may cause weight problem.The traditional mechanical buffers also have their own shortcomings such as small buffer stroke and being non-reusable.A Novel Buffer Lander-leg with Yoshimura core (NBLY) is proposed in this paper,inspired by the Buckling Restrained Brace(BRB).The design details of NBLY and parameter definitions of the core are presented.The finite element analysis modes have been employed to analyze the nonlinear mechanical behaviors of NBLY subjected to the cyclic loading.NBLY with four different core styles of hexagon,octagon,dodecagon and hexadecagon are analyzed and compared.The restraining ratio and cumulative dissipation energy ratio have been obtained to evaluate the energy absorption properties.The results show that the origami pattern has significant influences on the deformation ductility,plastic energy absorbing and axial load transferring to the core.The NBLY with octagon core has outstanding properties,especially the hysteretic energy dissipation and enhancement of compression capacity.The interaction mechanism between the core and encasing member constrains the deformation extensions and contributes to the frictional energy dissipation of the NBLYs.This paper provides a new conceptual design of buffer lander-leg for soft-landing missions.It can realize the reuse function as a buffer lander-leg with better loading-bearing and energy absorption behaviors.

关键词： Lander-leg structure Origami Energy absorption Cyclic loading Finite element analysis

Molecular cloning,characterization and promoter analysis of LbgCWIN1 and its expression profiles in response to exogenous sucrose during in vitro bulblet initiation in lily

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Horticultural Plant Journal 2024年第2期10卷 545-555页

作者： Cong Gao Shiqi Li Yunchen Xu Yue Liu Yiping Xia Ziming Ren Yun Wu Genomics and Genetic Engineering Laboratory of Ornamental Plants Institute of Landscape ArchitectureCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhouZhejiang 310058China Laboratory of Flower Bulbs Department of Landscape ArchitectureSchool of Civil Engineering and ArchitectureZhejiang Sci-Tech UniversityHangzhouZhejiang 310018China

Lily(Lilium spp.) is an important ornamental flower, which is mainly propagated by bulbs. Cell wall invertases(CWINs), which catalyze the irreversibly conversion of sucrose into glucose and fructose in the extracellular space, are key enzymes participating in sucrose allocation in higher plants. Previous studies have shown that CWINs play an essential role in bulblet initiation process in bulbous crops, but the underlying molecular mechanism remains unclear. Here, a CWIN gene of Lilium brownii var. giganteum(Lbg) was identified and amplified from genomic DNA. Quantitative RT-PCR assays revealed that the expression level of LbgCWIN1 was highly upregulated exactly when the endogenous starch degraded in non-sucrose medium during in vitro bulblet initiation in Lbg. Phylogenetic relationship, motif, and domain analysis of LbgCWIN1 protein and CWINs in other plant species showed that all sequences of these CWIN proteins were highly conserved. The promoter sequence of LbgCWIN1 possessed a number of alpha-amylase-, phytohormone-, light-and stress-responsive cis-elements. Meanwhile, β-glucuronidase(GUS) assay showed that the 459 bp upstream fragment from the translational start site displayed maximal promoter activity. These results revealed that LbgCWIN1 might function in the process of in vitro bulblet initiation and be in the response to degradation of endogenous starch.

关键词： Lilium brownii var.giganteum LbgCWIN1 Phylogenetic analysis Promoter analysis Bulblet initiation

Evaluating different levels of information on the calibration of building energy simulation models

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Building Simulation 2024年第4期17卷 657-676页

作者： Siyu Cheng Zeynep Duygu Tekler Hongyuan Ji Wenxin Li Adrian Chong Department of the Built Environment College of Design and EngineeringNational University of Singapore4 Architecture DriveSingapore117566Singapore school of Civil Engineering and architecture Chongqing University of Science and TechnologyChongqing401331China school of Energy and Environment Southeast UniversityNanjing210096China

A poorly calibrated model undermines confidence in the effectiveness of building energy simulation, impeding the widespread application of advanced energy conservation measures (ECMs). Striking a balance between information-gathering efforts and achieving sufficient model credibility is crucial but often obscured by ambiguities. To address this gap, we model and calibrate a test bed with different levels of information (LOI). Beginning with an initial model based on building geometry (LOI 1), we progressively introduce additional information, including nameplate information (LOI 2), envelope conductivity (LOI 3), zone infiltration rate (LOI 4), AHU fan power (LOI 5), and HVAC data (LOI 6). The models are evaluated for accuracy, consistency, and the robustness of their predictions. Our results indicate that adding more information for calibration leads to improved data fit. However, this improvement is not uniform across all observed outputs due to identifiability issues. Furthermore, for energy-saving analysis, adding more information can significantly affect the projected energy savings by up to two times. Nevertheless, for ECM ranking, models that did not meet ASHRAE 14 accuracy thresholds can yield correct retrofit decisions. These findings underscore equifinality in modeling complex building systems. Clearly, predictive accuracy is not synonymous with model credibility. Therefore, to balance efforts in information-gathering and model reliability, it is crucial to (1) determine the minimum level of information required for calibration compatible with its intended purpose and (2) calibrate models with information closely linked to all outputs of interest, particularly when simultaneous accuracy for multiple outputs is necessary.

关键词： calibration building energy simulation(BES) energy conservation measure(ECM) level of information field measurements

From“prototype”to“model”:Architectural and spatial development of Block A(1924—1945)of Istanbul’s Heybeliada Sanatorium

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Frontiers of Architectural Research 2024年第1期13卷 1-20页

作者： Deniz Avci-Hosanli Cansu Degirmencioglu Department of Interior architecture and Environmental Design Izmir University of EconomicsIzmir 35330Turkey TUM school of Engineering and Design Department of ArchitectureTechnical University of MunichMunich 80333Germany

This article examines Block A,the first block-style building in Heybeliada Sanatorium in Istanbul.The purpose of this research is to understand its architectural and spatial development and discuss how in fact it was a“prototype”of Turkish sanatoria.Approached with a three-step methodology(documentation/evaluation/results)this research conducts architectural and spatial analysis on Block A.Primary sources like architectural documentation and restitution drawings,the writings of the institution’s head doctor Tevfik Ismail Gökçe,periodicals on tuberculosis(TB),as well as pertinent literature are utilized.The findings demonstrate that Block A’s development(1924—1945)was the result of knowledge transfer that introduced the universal sanatorium design principles,spatial experiments,adaptation to sociocultural norms,and trial-and-error processes.Not only it had a major impact on shaping of the second block-type building in the complex,the“model”Block B,but it also became exemplary of the subsequent Turkish sanatoria.The originality of this article is its exploration of the changing and evolving Block A in its resonation with the cultural tensions of Turkey’s modernization process.This was established via the assessment of budgetary issues,medical developments and climatic experiments,the social issue of scarcity of TB beds in the country,spatial practices to separate the sexes as reflections of local traditions and culture in the shaping of spaces.

关键词： Sanatorium architecture Tuberculosis History of healthcare Early republican Turkey Istanbul

Influence of powder oxidation on powder properties and formability in H13 hot-work steels processed by electron beam melting

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Journal of Iron and Steel Research(International) 2024年第4期31卷 924-932页

作者： Wei Liu Yan Wang Li-xiong Han Ying-kang Wei Hui-ping Tang Shi-feng Liu school of Metallurgical Engineering Xi'an University of Architecture and TechnologyXi'an 710055ShaanxiChina school of Engineering Zhejiang University City CollegeHangzhou 310015ZhejiangChina

The oxygen content of metal powder is decisive for the recyclability of powder.The research on the effect of oxygen content on powder properties and material formability has practical significance for economical production with additive manufacturing while preventing the waste of resources.Here,we deliberately oxidized the powder by baking at high temperature to increase the oxygen content in the powder and gave the calculation method of the oxygen content in the powder oxidation film.The majority of oxygen element was found in the oxide particles in the powder and the oxide flm on the powder surface,which did affect the flowability of the powder.It is worth noting that the increase in the oxygen content does not change the phase of H13 steel,but it can promote the molten pool flow and obtain a smoother surface.The increase in the oxygen content in the powder is not the decisive factor for the formability and defects of the printed samples.It is the combined effect of the powder deformation,the increase in the oxygen content,and the impurity pollution after repeated use,which leads to the limitation of repeated utilization of the powder.

关键词： Additive manufacturing Electron beam melting H13 steel powder-Powder oxidation

Numerical simulation analysis of wind field above pavement surface in different landforms by computational fluid dynamics approach

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第3期11卷 559-573页

作者： Jian Ouyang Zhao Jiang Leiyu Ye Jing Li Peng Cao school of Civil Engineering and architecture Hainan University school of Transportation and Logistics Dalian University of Technology Hexagon Manufacturing Intelligence (Qingdao) Co. Ltd. China Tower Co. Ltd.Dalian Branch Faculty of architecture Civil and Transportation Engineering Beijing University of Technology

The temperature and moisture of the pavement structure can be greatly influenced by the wind speed above pavement surface. The wind speed above pavement surface not only is dominated by the wind speed of atmosphere, but also it is highly related to the landform and buildings around road. However, currently there are no studies about the wind field above pavement surface in consideration of the effect of the landform and buildings. A simulation method, which is combined with geographic information system(GIS), wind data from meteorological observatory and computational fluid dynamics(CFD) software, is employed to study the effect of the landform and the wind speed of atmosphere on the wind field above pavement surface. Three cases are studied, including an urban road, a coastal road and a mountainous road. Furthermore, the wind field distribution above road surface in different wind directions was studied in our work. Results indicate that the wind field above pavement surface can be greatly affected by the landforms, buildings and wind direction. This simulation method can provide reliable results for the wind field above pavement surface. The maximum relative errors between simulated and measured wind speed can be less than 20% in the analysis of the three cases. It is recommended that the CFD simulation method is a good tool to accurately know the wind field above pavement surface.

关键词： Wind field above pavement surface Computational fluid dynamics Landforms Geographic information system Simulation

Hollow cathode effect in radio frequency hollow electrode discharge in argon

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Chinese Physics B 2024年第3期33卷 496-502页

作者：贺柳良何锋欧阳吉庭 College of Science Beijing University of Civil Engineering and ArchitectureBeijing 102616China school of Physics Beijing Institute of TechnologyBeijing 100081China

Radio frequency capacitively coupled plasma source(RF-CCP)with a hollow electrode can increase the electron density through the hollow cathode effect(HCE),which offers a method to modify the spatial profiles of the plasma density.In this work,the variations of the HCE in one RF period are investigated by using a two-dimensional particle-in-cell/Monte-Carlo collision(PIC/MCC)model.The results show that the sheath electric field,the sheath potential drop,the sheath thickness,the radial plasma bulk width,the electron energy distribution function(EEDF),and the average electron energy in the cavity vary in one RF period.During the hollow electrode sheath's expansion phase,the secondary electron heating and sheath oscillation heating in the cavity are gradually enhanced,and the frequency of the electron pendular motion in the cavity gradually increases,hence the HCE is gradually enhanced.However,during the hollow electrode sheath's collapse phase,the secondary electron heating is gradually attenuated.In addition,when interacting with the gradually collapsed hollow electrode sheaths,high-energy plasma bulk electrons in the cavity will lose some energy.Furthermore,the frequency of the electron pendular motion in the cavity gradually decreases.Therefore,during the hollow electrode sheath's collapse phase,the HCE is gradually attenuated.

关键词： hollow cathode effect radio frequency hollow electrode particle-in-cell/Monte-Carlo collision(PIC/MCC)model

High catalytic performance of neodymium modified Co_(3)O_(4) for toluene oxidation

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Journal of Rare Earths 2024年第1期42卷 94-101,I0004页

作者： Yanqiong Hu Luyue Zhang Jianbei Zhang Yongjun Liu school of architecture and Environment Sichuan UniversityChengdu610065China National Engineering Research Center for Flue Gas Desulfurization Chengdu610065China

Co-based catalysts are the most promising catalysts in catalytic oxidation of volatile organic compounds(VOCs).Precious metal doping is adopted to improve the catalytic activity of toluene on Co_(3)O_(4) catalysts,but greatly increases its cost along with it.It is found that doping a small amount of rare earth(Ce,Pr,Sm and Nd)can dramatically promote the catalytic activity of Co_(3)O_(4).Especially,the Nd-doped Co_(3)O_(4) catalyst exhibits excellent catalytic activity with a toluene removal rate of 90% at 162.1℃,which is even better than that of Pt-doped Co_(3)O_(4).Compared with other rare earth metal doping,the Nd doping leads to a higher ratio of Co^(3+)/Co^(2+) and has more oxygen vacancies.The in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)experiments show that the lattice oxygen of Nd-Co sample can be utilized at a quite low temperature,while that of pure Co_(3)O_(4) cannot engage in oxidation reaction when the temperature is below 200℃,which visually demonstrates the main reason for the improved catalytic performance of Nd-Co catalyst.

关键词： Rare earth metals Nd Co_(3)O_(4) Toluene catalytic oxidation Oxygen vacancy Lattice oxygen

Modeling the Interaction between Vacancies and Grain Boundaries during Ductile Fracture

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 2019-2034页

作者： Mingjian Li Ping Yang Pengyang Zhao Department of Engineering Mechanics School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

The experimental results in previous studies have indicated that during the ductile fracture of pure metals,vacancies aggregate and form voids at grain boundaries.However,the physical mechanism underlying this phenomenon remains not fully understood.This study derives the equilibrium distribution of vacancies analytically by following thermodynamics and the micromechanics of crystal defects.This derivation suggests that vacancies cluster in regions under hydrostatic compression to minimize the elastic strain energy.Subsequently,a finite element model is developed for examining more general scenarios of interaction between vacancies and grain boundaries.This model is first verified and validated through comparison with some available analytical solutions,demonstrating consistency between finite element simulation results and analytical solutions within a specified numerical accuracy.A systematic numerical study is then conducted to investigate the mechanism that might govern the micromechanical interaction between grain boundaries and the profuse vacancies typically generated during plastic deformation.The simulation results indicate that the reduction in total elastic strain energy can indeed drive vacancies toward grain boundaries,potentially facilitating void nucleation in ductile fracture.

关键词： Ductile fracture vacancy grain boundary micromechanical finite element method