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Application of GNSS-PPP on Dynamic Deformation Monitoring of Offshore Platforms

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China Ocean Engineering 2024年第2期38卷 352-361页

作者： YU li-na XIONG kuan GAO Xi-feng li Zhi FAN li-long ZHANG Kai Institute of Ocean Energy and Intelligent Construction Tianjin University of TechnologyTianjin 300384China China Railway Construction Bridge Engineering Bureau Group Co.LTD Tianjin 300300China School of Civil Engineering Tianjin UniversityTianjin 300072China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong KongChina State Key Laboratory of Precision Blasting Jianghan UniversityWuhan 430056China

The real-time dynamic deformation monitoring of offshore platforms under environmental excitation is crucial to their safe *** Global Navigation Satellite System-Precise Point Positioning(GNSS-PPP)has been considered for this purpose,its monitoring accuracy is relatively ***,the influence of background noise on the dynamic monitoring accuracy of GNSS-PPP remains ***,it is imperative to further validate the feasibility of GNSS-PPP for deformation monitoring of offshore *** address these concerns,vibration table tests with different amplitudes and frequencies are *** results demonstrate that GNSS-PPP can effectively monitor horizontal vibration displacement as low as±30 mm,which is consistent with ***,the spectral characteristic of background noise in GNSS-PPP is similar to that of GNSS-RTK(Real Time Kinematic).Building on this observation,an improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)has been proposed to de-noise the data and enhance the dynamic monitoring accuracy of *** monitoring application research is also undertaken,successfully extracting and analyzing the dynamic deformation of an offshore platform structure under environmental excitation using GNSS-PPP monitoring in conjunction with improved CEEMDAN *** comparing the de-noised dynamic deformation trajectories of the offshore platform during different periods,it is observed that the platform exhibits reversible alternating vibration responses under environmental excitation,with more pronounced displacement deformation in the direction of load *** research results confirm the feasibility and potential of GNSS-PPP for dynamic deformation monitoring of offshore platforms.

关键词： GNSS-PPP offshore platform dynamic deformation monitoring improved CEEMDAN de-noising

Fracture mechanism of inclusions in thick plate center under tensile loading

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Journal of Iron and Steel Research International 2024年第5期31卷 1196-1209页

作者： Lei Hu li-qin Zhang Feng Hu Guo-hong Zhang kuan Zheng Collaborative Innovation Center for Advanced Steels Wuhan University of Science and TechnologyWuhan430081HubeiChina Department of Applied Physics Wuhan University of Science and TechnologyWuhan430081HubeiChina Analysis and Testing Center Wuhan University of Science and TechnologyWuhan430081HubeiChina

Segregation of solute atoms in the center of thick plates of the tempered steel can cause an inhomogeneous structural transformation and generate micron-sized inclusions,which leads to lamellar tearing of thick plate and decreases the plasticity and *** formation and fragmentation mechanisms of micron-sized inclusions,like MnS and(Nb,Ti)C,in the center of thick plates were investigated by using thermodynamic calculations,finite element simulations,and electron backscatter diffraction characterization *** results show that micron-sized inclusions nucleate and grow in the liquid phase,and under tensile loading,they exhibit three fragmentation *** local stress during the fragmentation of inclusions is lower than the critical fracture stress of adjacent grains,and phase boundaries can effectively impede crack propagation into the *** existence of a low proportion of high-angle grain boundaries(58.1%)and high Kernel average misorientation value(0.534°)in the segregation band promotes inclusions fragmentation and crack *** difference in crack initiation and propagation direction caused by the morphology of inclusions and physical properties,as well as different matrix arrest abilities,is the main reasons for the diversity of inclusion fragmentation.

关键词： Thick plate Inclusion Finite element simulation Critical fracture stress Fracture mechanism

Study on the effective elastic performance of composites containing decagonal symmetric two-dimensional quasicrystal coatings

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1655-1664页

作者： Yurun wu Lu li lianhe li School of Mathematics and Science Inner Mongolia Normal UniversityHohhot 010022China Inner Mongolia Applied mathematics Center Hohhot 010022China Key Laboratory of Infinite Dimensional Hamiltonian System and Its Algorithm Application Ministry of EducationHohhot 010022China

On account of the Mori-Tanaka approach,the effective elastic performance of composites containing decagonal symmetric two-dimensional(2D)quasicrystal(QC)coatings is *** expressions for the effective elastic constants of rare-earth QC reinforced magnesium-based composites are *** discussion is presented on the effects of the volume fraction of the inclusions,the aspect ratio of the inclusions,the coating thickness,and the coating material parameters on the effective elastic constants of the *** results indicate that considering the coating increases the effective elastic constants of the composites to some extent.

关键词： Mori-Tanaka approach coated inclusion decagonal symmetric twodimensional(2D)quasicrystal(QC)

Mirrorless MEMS imaging:a nonlinear vibrational approach utilizing aerosol-jetted PZT-actuated fiber MEMS scanner for microscale illumination

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Microsystems & Nanoengineering 2024年第1期10卷 175-192页

作者： Wei-Chih Wang Ming-Yao li kuan-Chang Peng Yi-Feng Hsu Benjamin Estroff Pao-Yun Yen David Schipf Wen-Jong wu Department of Power Mechanical Engineering National Tsing Hua UniversityNo.101Section 2Kuang-Fu RoadHsinchuTaiwan 30013China Institute of NanoEngineering and Microsystems National Tsing Hua UniversityNo.101Section 2Kuang-Fu RoadHsinchuTaiwan 30013China Department of Mechanical Engineering University of WashingtonSeattleWA 98195USA Department of Electrical Engineering University of WashingtonSeattleWA 98195USA Department of Engineering Science and Ocean Engineering National Taiwan UniversityTaiwanChina

This study introduces a novel image capture and lighting techniques using a cutting-edge hybrid MEMS scanner system designed for compact microscopic *** scanner comprises a tapered optical fiber waveguide and innovative aerosol-jet printed PZT(lead zirconate titanate)bimorph push-pull actuators on a stainless-steel substrate,effectively addressing issues that are commonly associated with PZT on silicon substrates such as fracture and layer *** leveraging nonlinear vibration,the scanner achieves a spiral scan pattern from a single signal input,in addition to the expected two-dimensional scanning and target illumination from two phase-shifted *** capability is further enhanced by a novel process to taper the optical fiber,which reduces illumination scattering and tunes the fiber to the resonant frequencies of the *** precisely tapered tip enables large fields of view while maintaining independent 2-axis scanning through one-degree-of-freedom *** validation showcases the successful generation of a spiral scan pattern with a 60μm diameter scan area and a 10 Hz frame rate,effectively reconstructing scanned images of 5μm lines,cross patterns(15μm in length with a 5μm gap),and structures of a Psychodidae wing.

关键词： steel fiber scanner

Numerical investigation on thermomechanical behavior of alumina–calcium hexaluminate refractories for purging plug

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Journal of Iron and Steel Research International 2024年第2期31卷 389-400页

作者： li-ping Pan Ya-wei li Fang-guan Tan Yi-chen Chen Yang-fan Xu Zhu He Bao-kuan li The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina National-Provincial Joint Engineering Research Center of High Temperature Materials and lining Technology Wuhan University of Science and TechnologyWuhan430081HubeiChina

Alumina–spinel refractories used in slit-type purging plugs are susceptible to cross-sectional damage,resulting in a serious mismatch between their service life and that of ***–calcium hexaluminate refractories have gradually become the new trend in purging plug materials with the development of refining *** thermomechanical damage of slit-type purging plugs with alumina–calcium hexaluminate refractory was investigated by the thermo-solid coupling *** with the polynomial fitting and design of experiments methods,the influence of thermophysical parameters on temperature and thermal stress of alumina–calcium hexaluminate refractories for purging plugs was systematically *** results show that the maximum thermal stress of the purging plugs appears during the stages of steel transporting and stirring,and the vulnerable parts are located above Y=0.323 *** thermal conductivity and the coefficient of thermal expansion of the material are the most sensitive parameters to the temperature and thermal stress inside the structure,*** addition of more calcium hexaluminate can relieve the stress concentration and large deformation around the ***,when the content of calcium hexaluminate is 47 wt.%and in the form of aggregate-binder,the temperature and thermal stress distribution inside the refractory are optimal,which can effectively improve the service life of the slit-type purging plug.

关键词： Purging plug Thermomechanical damage Refractory Design of experiments method Stress

Analysis of impact pressure,rock-breaking effect,and ground vibration induced by the disposable CO_(2)fracturing tube

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3099-3121页

作者： Chong Yu Yongan Ma Haibo li Shouchun Deng Yafei Hao kuan Zhu State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China Explosives Co.Ltd. Changsha410000China wuhan University of Science and Technology Wuhan430000China Gezhouba EXPL(Hunan)Technology Co.Ltd. Liuyang410300China

The technology of expansion fracturing with liquid CO_(2)(EFLCO_(2))has attracted increasing attention due to reduced vibration and *** disposable fracturing tube has been developed and is gradually replacing the Cardox ***,there is a lack of impact pressure testing of disposable tubes under real working conditions,selection of gas explosion design parameters,and systematic analysis of blasting *** limitation has constrained the widespread application of disposable fracturing tubes in engineering.A joint monitoring of the pressure-time curves in the disposable tubes and boreholes was *** rock-breaking effect of varying hole spacing parameters in the EFLCO_(2)design was analyzed,and a systematic study was carried out on the vibration peak value,frequency,and energy *** results show that(1)the pressure distribution characteristics,stress peak value,and duration in the disposable tubes are different from those of Cardox tubes,which show multi-peak distribution,low-pressure peak value,and short *** correlation between the pressure in the disposable tube,filling pressure,and liquid CO_(2)weight is established,and a theoretical calculation method for the borehole wall pressure is proposed;(2)The hole spacing in rocks of different hardness is suggested;and(3)At the same scale distance,the peak particle velocity(PPV)caused by EFLCO_(2)(PPVCO_(2))is significantly smaller than that caused by blasting(PPVexplosive).The ratio of PPVexplosive to PPVCO_(2)is a power function related to scale distance,and a distance-related zonality exist in this *** frequency composition of the vibration signal caused by EFLCO_(2)is relatively simple with a narrow frequency *** PPV and energy are mainly concentrated in the low-frequency *** research contributes to the optimization of disposable fracturing tubes,gas explosion design,and vibration hazard control.

关键词： Disposable tube liquid CO_(2) Impact pressure Hole spacing Vibration effect Cardox tube

Influence mechanism of government subsidy on the green transformation of coal company in China

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International Journal of Mining Science and Technology 2024年第7期34卷 1033-1040页

作者： Xiaolei li Changsong wu School of Management China University of Mining and Technology-BeijingBeijing 100083China School of Economics and Management China University of Mining and TechnologyXuzhou 221116China

The optimization of government subsidies to enhance the efficiency of coal companies’green transformation constitutes a critical component in the pursuit of global *** investigate the influence mechanism of government subsidies on the green transformation using data from the listed coal companies in China from 2007 to *** to our findings and hypothesis testing,previous government subsidies did not have a significant direct impact on coal companies’green ***,government subsidies can help coal companies transition to greener practices by promoting innovative green ***,we confirmed an indirect route:that government subsidies enable the adoption of low-carbon initiatives,which in turn could facilitate the transition of coal companies towards green *** addition,we discovered that the coal company’s digitization will improve this indirect ***,we propose increasing the effectiveness of government subsidies in facilitating coal companies’transition to green practices by focusing on technological advancements and enhancing company digitalization.

关键词： Government subsidy Green transformation Coal company Digitalization Innovation

Development of component stiffness equations for thread-fixed one-side bolt connections to an enclosed rectangular hollow section column under tension

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 568-586页

作者： Fu-Wei wu Yuan-Qi li Department of Structural Engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China

The derivation and validation of analytical equations for predicting the tensile initial stiffness of threadfixed one-side bolts(TOBs),connected to enclosed rectangular hollow section(RHS)columns,is presented in this *** unknown stiffness components are considered:the TOBs connection and the enclosed RHS ***,the trapezoidal thread of TOB,as an equivalent cantilevered beam subjected to uniformly distributed loads,is analyzed to determine the associated *** on the findings,the thread-shank serial-parallel stiffness model of TOB connection is *** analysis of the tensile stiffness of the enclosed RHS face due to two bolt forces,the four sidewalls are treated as rotation constraints,thus reducing the problem to a two-dimensional plate *** to the load superposition method,the deflection of the face plate is resolved into three components under various boundary and load *** to the plate deflection theory of Timoshenko,the analytical solutions for the three deflections are derived in terms of the variables of bolt spacing,RHS thickness,height to width ratio,***,the validity of the above stiffness equations is verified by a series of finite element(FE)models of T-stub *** proposed component stiffness equations are an effective supplement to the component-based method.

关键词： initial stiffness component based method thread-fixed one-side bolt rectangular hollow sections analytical equation

Numerical study on local failures of reinforced concrete slabs against underwater close-in explosions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第8期25卷 650-669页

作者： Fei ZHOU Hedong li Hao wu College of Civil Engineering Tongji UniversityShanghai 200092China School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou 310018China

Reinforced concrete(RC)slabs are the primary load-carrying member of underwater *** can suffer severe local failures such as cratering,spalling,or breaching as a result of underwater close-in(UWCI)*** this study,we established a fully validated high-fidelity finite element analysis approach to precisely reproduce the local failures of RC slabs after a UWCI explosion.A recently proposed dynamic constitutive model is used to describe wet *** effects of free water content on the material properties,including the tensile/compressive strength,elastic modulus,strain rate effect,failure strength surface,and equation of state,are comprehensively calibrated based on existing test *** calibrated material parameters are then verified by a single-element test.A high-fidelity finite element analysis(FEA)approach of an RC slab subjected to a UWCI explosion is established using an arbitrary Lagrangian-Eulerian(ALE)*** previous UWCI explosion tests on RC orifice targets and underwater contact explosion tests on saturated concrete slabs showed that the established FEA approach could accurately reproduce the pressure-time history in water and damage patterns,including the cracking,cratering,and spalling,of the RC orifice target and saturated concrete ***,parametric studies conducted by simulating an RC slab subjected to a UWCI explosion showed that:(i)the local failure of an RC slab enlarges with increased charge weight,reduced standoff distance,and reduced structural thickness;(ii)compared to a water-backed RC slab,an air-backed RC slab exhibits much more obvious local and structural ***,to aid the anti-explosion design of relevant underwater facilities,based on over 90 simulation cases empirical formulae are summarized to predict local failure modes,i.e.,no spall,spall,and breach,of water-and air-backed RC slabs subjected to a UWCI explosion.

关键词： Reinforced concrete slab(RC) Underwater close-in(UWCI)explosion Saturated concrete Failure modes Numerical simulation