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An Icy Worlds life detection strategy based on Exo-AUV

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Science China Earth Sciences 2024年第11期67卷 3515-3535页

作者： Bin wang Hongde QIN National Key Laboratory of Autonomous Marine Vehicle Technology Harbin Engineering UniversityHarbin 150001China Shipbuilding Engineering College Harbin Engineering UniversityHarbin 150001China

In the solar system, Icy Worlds such as Europa and Enceladus hold great potential for extraterrestrial life and may provide humanity an answer, within this century, to the age-old question of life beyond Earth. Exo-AUV technology shows promise in life detection in the icy shell, at the ice-water interface and on the seafloor of exo-ocean. Space agencies, including NASA and DLR, are enthusiastic about deploying Exo-AUVs to explore life in these regions. However, the where and how to find life, the technologies to be utilized and the goals to be achieved are crucial aspects for future Exo-AUV life detection missions on Icy Worlds. This study delves into a hypothetical mission of life detection on Europa, discussing science goals,detectable objects, potential regions and biogenic analysis for Icy Worlds. It proposes a life detection strategy for Icy Worlds based on Exo-AUVs, presents key contextual elements for Exo-AUV operations, outlines technological requirements for hull,payloads and autonomy, introduces the current state of Exo-AUV research and addresses existing challenges. This study also suggests a roadmap for conceptual development of Exo-AUV and a Concept of Operations for Multiple Exo-AUV System(ConOps for MEAS). This system aims to assist planetary scientists and astrobiologists in exploring Icy Worlds, identifying robust biosignatures and potentially discovering extant organisms, even prebiotic chemical systems.

关键词： Icy Worlds Europa Life detection Biological potential Exo-AUV

Shock wave configurations and reflection hysteresis outside a planar Laval nozzle

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Chinese Journal of Aeronautics 2015年第5期28卷 1362-1371页

作者： wang Dan Yu Yong School of Aerospace Engineering Beijing Institute of Technology

When the pressure ratio increases from the perfectly expanded condition to the third limited condition in which a normal shock is located on the exit plane, shock wave configurations outside the nozzle can be further assorted as no shock wave on the perfectly expanded condition, weak oblique shock reflection in the regular reflection （RR） pressure ratio condition, shock reflection hysteresis in the dual-solution domain of pressure ratio condition, Mach disk configurations in the Mach reflection （MR） pressure ratio condition, the strong oblique shock wave configurations in the corresponding condition, and a normal shock forms on the exit plane in the third limited con- dition. Every critical pressure ratio, especially under regular reflection and Mach reflection pressure ratio conditions, is deduced in the paper according to shock wave reflection theory. A hysteresis phenomenon is also theoretically possible in the dual-solution domain. For a planar Laval nozzle with the cross-section area ratio being 5, different critical pressure ratios are counted in these con- ditions, and numerical simulations are made to demonstrate these various shock wave configurations outside the nozzle. Theoretical analysis and numerical simulations are made to get a more detailed understanding about the shock wave structures outside a Laval nozzle and the RR←→MR transition in the dual-solution domain.

关键词： Critical pressure ratios Hysteresis Mach reflection Regular reflection Shock wave configurations

A critical review of preparation design and workability measurement of concrete material for largescale 3D printing

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Frontiers of Structural and Civil Engineering 2018年第3期12卷 382-400页

作者： Guowei MA Li wang College of Architecture and Civil Engineering Beijing University of Technology Beijing 100124 China School of Civil Environmental and Mining Engineering The University of Western Australia Crawley WA 6009 Australia School of Mechanics and Civil engineering China University of Mining & Technology at Beijing Beijing 100083 China

In recent few years, significant improvement has been made in developing largescale 3D printers to accommodate the need of industrial-scale 3D printing. It is of great feasibility to construct structural components and buildings by means of 3D concrete printing. The major issues of this innovative technique focus on the preparation and optimization of concrete materials which possess favourable printable properties as well as the measurement and evaluation methods of their workability. This paper firstly introduces three largescale 3D printing systems that have been successfully applied in construction industry. It then summarizes the commonly used raw materials in concrete manufacturing. Critical factors that should be particularly controlled in material preparation are specified. Easy-extrusive, easy-flowing, well-buildable, proper setting time and low shrinkage are significant for concrete mixture to meet the critical requirements of a freeform construction process. Thereafter, measuring methods that can be employed to assess the fresh and hardened properties of concrete at early stages are suggested. Finally, a few of evaluation methods are presented which may offer certain assistance for optimizing material preparation. The objective of this work is to review current design methodologies and experimental measurement and evaluation methods for 3D printable concrete materials and promote its responsible use with largescale 3D printing technology.

关键词： 3D printing concrete material printable property workability measurement construction automation

Generalized F-Test for High Dimensional Regression Coefficients of Partially Linear Models

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Journal of Systems Science & Complexity 2017年第5期30卷 1206-1226页

作者： wang Siyang CUI Hengjian School of Statistics and Mathematics Central University of Finance and EconomicsBeijing 100081China School of Mathematical Sciences Capital Normal UniversityBeijing 100048China

This paper proposes a test procedure for testing the regression coefficients in high dimensional partially linear models based on the F-statistic. In the partially linear model, the authors first estimate the unknown nonlinear component by some nonparametric methods and then generalize the F-statistic to test the regression coefficients under some regular conditions. During this procedure, the estimation of the nonlinear component brings much challenge to explore the properties of generalized F-test. The authors obtain some asymptotic properties of the generalized F-test in more general cases,including the asymptotic normality and the power of this test with p/n ∈(0, 1) without normality assumption. The asymptotic result is general and by adding some constraint conditions we can obtain the similar conclusions in high dimensional linear models. Through simulation studies, the authors demonstrate good finite-sample performance of the proposed test in comparison with the theoretical results. The practical utility of our method is illustrated by a real data example.

关键词： Generalized F-test high dimensional regression partially linear models power of test.

Sub-2 nm IrO_(2)/Ir nanoclusters with compressive strain and metal vacancies boost water oxidation in acid

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Nano Research 2023年第1期16卷 334-342页

作者： Zhijuan Liu Guangjin wang Jinyu Guo Shuangyin wang Shuang-Quan Zang Henan Key Laboratory of Crystalline Molecular Functional Materials Henan International Joint Laboratory of Tumor Theranostical Cluster MaterialsGreen Catalysis Centerand College of ChemistryZhengzhou UniversityZhengzhou 450001China Hunan University State Key Laboratory of Chem/Bio-sensing and ChemometricsCollege of Chemistry and Chemical EngineeringChangsha 410082China School of Materials Science and Energy Engineering Foshan UniversityFoshan 528000China

IrO_(2)exhibits good stability but limited electrocatalytic activity for oxygen evolution reaction in *** engineering is an effective strategy to improve the intrinsic ability of electrocatalysts by tailoring their electronic ***,we have successfully synthesized IrO_(2)/Ir heterophase with compressive strain and metal vacancies via a simple substitution-etching *** virtue of the solubility of Cr in strong alkali,metal vacancies could be formed at surface after etching Cr-doped IrO_(2)/Ir in alkali,which leaded to modulated electronic ***,the substitution of Cr with smaller atom radius would induce the formation of compressive strain and the relocated atoms made the d-band center *** the regulated electronic structure and tuned d-band center,the obtained electrocatalyst only needed 285 mV to reach 10 mA·cm^(−2)in 0.1 M *** kinetic has been rapidly accelerated as indicated by the smaller Tafel slope and charge transfer *** calculations revealed that the d-band center and charge density distribution have been regulated with the introduction of defects in IrO_(2)/Ir,which significantly decreased the free energy barrier of rate determining *** work provides a valuable reference to design effective and defects-rich electrocatalysts.

关键词： IrO_(2)/Ir nanoclusters compressive strain metal vacancies d-band center water oxidation in acid

Panel/full-span free-wake coupled method for unsteady aerodynamics of helicopter rotor blade

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Chinese Journal of Aeronautics 2013年第3期26卷 535-543页

作者： Tan Jianfeng wang Haowen School of Aerospace Tsinghua University

A full-span free-wake method is coupled with an unsteady panel method to accurately predict the unsteady aerodynamics of helicopter rotor blades in hover and forward flight. The unsteady potential-based panel method is used to consider aerodynamics of finite thickness multi-bladed rotors, and the full-span free-wake method is applied to simulating dynamics of rotor wake. These methods are tightly coupled through trailing-edge Kutta condition and by converting doublet-wake panels to full-span vortex filaments. A velocity-field integration technique is also adopted to overcome singularity problem during the interaction between the rotor wake and blades. Helicopter rotors including Caradonna–Tung, UH-60A, and AH-1G rotors, are simulated in hover and forward flight to validate the accuracy of this approach. The predicted aerodynamic loads of rotor blades agree well with available measured data and computational fluid dynamics （CFD） results, and the unsteady dynamics of rotor wake is also well simulated. Compared to CFD, the present method obtains accurate results more efficiently and is suitable to rotorcraft aeroelastic analysis.

关键词： Free wake method Helicopter rotor Rotor wake Unsteady aerodynamics Unsteady panel method

A new procedure for investigating three-dimensional stress fields in a thin plate with a through-the-thickness crack

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Science China(Physics,Mechanics & Astronomy) 2018年第6期61卷 50-61页

作者： Dake Yi TzuChiang wang College of Mechanics and Materials Hohai University The State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences

In the paper, a new procedure is proposed to investigate three-dimensional fracture problems of a thin elastic plate with a long through-the-thickness crack under remote uniform tensile loading. The new procedure includes a new analytical method and high accurate finite element simulations. In the part of theoretical analysis, three-dimensional Maxwell stress functions are employed in order to derive three-dimensional crack tip fields. Based on the theoretical analysis, an equation which can describe the relationship among the three-dimensional J-integral J(z), the stress intensity factor K(z) and the tri-axial stress constraint level Tz(z) is derived first. In the part of finite element simulations, a fine mesh including 153360 elements is constructed to compute the stress field near the crack front, J(z) and Tz(z). Numerical results show that in the plane very close to the free surface, the K field solution is still valid for in-plane stresses. Comparison with the numerical results shows that the analytical results are valid.

关键词： three-dimensional fracture analysis out-of-plane constraint three-dimensional J-integral

SIMULATION OF THE INTERFACED STRUCTURAL COMPONENT BASED ON A MULTIPLE-TIME-SCALE ALGORITHM

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Acta Mechanica Solida Sinica 2014年第4期27卷 353-363页

作者： Keke Tang Xianqiao wang Key Laboratory of Pressure Systems and Safety Ministry of Education School of Mechanical and Power Engineering East China University of Science and Technology Department of Mechanical and Aerospace Engineering The George Washington University Washington DC 20052 USA

A multiple-time-scale algorithm is developed to numerically simulate certain structural components in civil structures where local defects inevitably exist. Spatially, the size of local defects is relatively small compared to the structural scale. Different length scales should be adopted considering the efficiency and computational cost. In the principle of physics, different length scales are stipulated to correspond to different time scales. This concept lays the foundation of the framework for this multiple-time-scale algorithm. A multiple-time-scale algorithm, which involves different time steps for different regions, while enforcing the compatibility of displacement, force and stress fields across the interface, is proposed. Furthermore, a defected beam component is studied as a numerical sample. The structural component is divided into two regions： a coarse one and a fine one; a micro-defect exists in the fine region and the finite element sizes of the two regions are diametrically different. Correspondingly, two different time steps are adopted. With dynamic load applied to the beam, stress and displacement distribution of the defected beam is investigated from the global and local perspectives. The numerical sample reflects that the proposed algorithm is physically rational and computationally efficient in the potential damage simulation of civil structures.

关键词： multiple-time-scale algorithm defected beam interface structural component civil structures

Free Vibration of Elastically Constrained Single-Layered MoS_(2)

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Acta Mechanica Solida Sinica 2022年第3期35卷 421-433页

作者： Jingnong Jiang Lifeng wang School of Mathematics and Statistics Southwest UniversityChongqing 400715China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Free vibration of elastically constrained rectangular single-layered M0S_(2)is investigated by using a nonlocal Kirchhoff plate model with an initial *** variationally consistent elastically constrained boundary conditions are obtained by using the weighted residual method,while the governing equations of the nonlocal Kirchhoff plate model are known.A modified Fourier series method is applied to study the vibrational behaviors of elastically constrained nonlocal Kirchhoff plate *** convergence and reliability of the modified Fourier series method is verified via comparison with the finite element method.A comprehensive parametric study is performed to show the influences of the boundary elastic constant,nonlocal parameter and initial stress on the vibrational behaviors of single-layered *** results should be good for the design of nanoresonators.

关键词： Single-layered M0S_(2) Vibration Nonlocal elasticity theory Elastic boundary condition