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Applied Mathematics and Mechanics(English Edition) 2020年第4期41卷 567-586页

作者： Zhiwei ZHOU Meixia CHEN Kun XIE School of naval architecture and Ocean engineering Huazhong University of Science and Technology college of engineering Huazhong Agricultural University

The free vibration of axially functionally graded(FG) tapered Timoshenko curved beams is studied with the numerical approach. By using the non-uniform rational B-spline(NURBS) basis functions, the exact geometry and the generalized displacement?eld are formulated. Variable geometric parameters and material properties, including the curvature, cross-sectional area, area moment of inertia, mass density, and Young’s modulus, are expanded as functions of the coordinate in a parametric domain. Based on Hamilton’s principle, the weak formulation is derived by applying a re?ned constitutive relation which considers the thickness e?ect. Natural frequencies and mode shapes are obtained from the eigenvalue equation. Circular, elliptic, and parabolic curved beams are considered in numerical examples. The obtained results are in good agreement with those in the existing studies and those calculated by the ?nite element software ***, the e?ects of the material gradient, taper ratio, slenderness ratio, and heightspan ratio on vibration behaviors are discussed.

关键词： free vibration functionally graded(FG) material non-uniform crosssection curved beam variable curvature thickness effect

Smart contract applications in the built environment: How prepared are Nigerian construction stakeholders?

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Frontiers of engineering Management 2024年第1期11卷 50-61页

作者： Andrew EBEKOZIEN Clinton AIGBAVBOA Samuel Adeniyi ADEKUNLE Mohamad Shaharudin SAMSURIJAN John ALIU Bernard Martins ARTHUR-AIDOO Godpower Chinyeru AMADI Department of Construction Management and Quantity Surveying University of JohannesburgJohannesburg 2006South Africa School of Social Sciences Universiti Sains MalaysiaGelugor11800 USM PenangMalaysia Department of Quantity Surveying Auchi PolytechnicAuchiNigeria Institute for Resilient Infrastructure Systems College of EngineeringUniversity of GeorgiaAthensGA 30602USA Department of Building Technology Faculty of Built EnvironmentAccra Technical UniversityAccraGhana Nigerian Institute of Management Port HarcourtNigeria

Studies have demonstrated that advanced technology,such as smart contract applications,can enhance both pre-and post-contract administration within the built environment *** contract technology,exemplifying blockchain technologies,has the potential to improve transparency,trust,and the security of data transactions within this ***,there is a dearth of academic literature concerning smart contract applications within the construction industries of developing countries,with a specific focus on ***,this study seeks to explore the relevance of smart contract technology and address the challenges impeding its adoption,offering strategies to mitigate the obstacles faced by smart contract *** investigate the stakeholders,this research conducted 14 virtual interview sessions to achieve data *** interviewees encompassed project management practitioners,senior management personnel from construction companies,experts in construction dispute resolution,professionals in construction software,and representatives from government construction *** data obtained from these interviews underwent thorough analysis employing a thematic *** study duly recognizes the significance of smart contract applications within the *** the 12 identified barriers,issues such as identity theft and data leakage,communication and synchronization challenges,high computational expenses,lack of driving impetus,excessive electricity consumption,intricate implementation processes,absence of a universally applicable legal framework,and the lack of a localized legal framework were recurrent impediments affecting the adoption of smart contract applications within the *** study also delves into comprehensive measures to mitigate these *** conclusion,this study critically evaluates the relevance of smart contract applications within the built environment,with a specific focus on promoting their *** may serve

关键词： built environment industry digitalization Nigeria smart contract technological revolution

Scale Effects on Propeller Cavitating Hydrodynamic and Hydroacoustic Performances with Non-uniform Inflow

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Chinese Journal of Mechanical engineering 2013年第2期26卷 414-426页

作者： YANG Qiongfang WANG Yongsheng ZHANG Zhihong college of Marine Power engineering Naval University of Engineering college of Science Naval University of Engineering

Considering the lack of theoretical models and ingredients necessary to explain the scaling of the results of propeller cavitation inception and cavitating hydroacoustics from model tests to full scale currently, and the insufficient reflection of the nuclei effects on cavitation in the numerical methods, the cavitating hydrodynamics and cavitation low frequency noise spectrum of three geometrically similar 7-bladed highly skewed propellers with non-uniform inflow are addressed. In this process, a numerical bridge from the multiphase viscous simulation of propeller cavitation hydrodynamics to its hydro-acoustics is built, and the scale effects on performances and the applicability of exist scaling law are analyzed. The effects of non-condensable gas（NCG） on cavitation inception are involved explicitly in the improved Sauer＇s cavitation model, and the cavity volume acceleration related to its characteristic length is used to produce the noise spectrum. Results show that, with the same cavitation number, the cavity extension on propeller blades increases with diameter associated with an earlier shift of the beginning point of thrust decline induced by cavitation, while the three decline slopes of thrust breakdown curves are found to be nearly the same. The power of the scaling law based on local Reynolds number around 0.9R section is determined as 0.11. As for the smallest propeller, the predominant tonal noise is located at blade passing frequency（BPF）, whereas 2BPF for the middle and both 2BPF and 3BPF for the largest, which shows the cavitating line spectrum is fully related to the interaction between non-uniform inflow and fluctuated cavity volume. The predicted spectrum level exceedance from the middle to the large propeller is 6.65 dB at BPF and 5.94 dB at 2BPF. Since it just differs less than 2 dB to the increment obtained by empirical scaling law, it is inferred that the scale effects on them are acceptable with a sufficient model scale, and so do the scaling

关键词： propeller cavitation inception cavitation noise scale effect cavitation model turbulence model

Fully Nonlinear Time Domain Analysis for Hydrodynamic Performance of An Oscillating Wave Surge Converter

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China Ocean engineering 2018年第5期32卷 582-592页

作者： SUN Shi-yan SUN Shi-li WU Guo-xiong School of naval architecture & Ocean engineering Jiangsu University of Science and Technology college of Shipbuilding engineering Harbin Engineering University Department of Mechanical engineering University College London

The hydrodynamic behaviour of an oscillating wave surge converter(OWSC) in large motion excited by nonlinear waves is investigated. The mechanism through which the wave energy is absorbed in the nonlinear system is analysed. The mathematical model used is based on the velocity potential theory together with the fully nonlinear boundary conditions on the moving body surface and deforming free surface. The problem is solved by the boundary element method. Numerical results are obtained to show how to adjust the mechanical properties of the OWSC to achieve the best efficiency in a given wave, together with the nonlinear effect of the wave height. Numerical results are also provided to show the behaviour of a given OWSC in waves of different frequencies and different heights.

关键词： wave energy oscillating wave surge converter nonlinear wave/structure interactions boundary element method

Numerical Study on Air Turbines with Enhanced Techniques for OWC Wave Energy Conversion

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China Ocean engineering 2017年第5期31卷 517-527页

作者： CUI Ying HYUN Beom-Soo KIM Kilwon Department of Ocean engineering College of EngineeringOcean University of China Division of naval architecture and Ocean engineering Korea Maritime and Ocean University

In recent years,the oscillating water column(OWC) wave energy converter,which can capture wave energy from the ocean,has been widely applied all over the *** the essential part of the OWC system,the impulse and Wells turbines are capable of converting the low pressure pneumatic energy into the mechanical shaft *** an enhanced technique,the design of endplate or ring attached to the blade tip is investigated numerically in this paper.3 D numerical models based on a CFD-software FLUENT 12.0 are established and validated by the corresponding experimental results from the reports of Setoguchi et al.(2004) and Takao et al.(2001).Then the flow fields and non-dimensional evaluating coefficients are calculated and analyzed under steady *** show that the efficiency of impulse turbine with ring can reach up to 0.49 when Ф=1,which is 4% higher than that in the cases for the endplate-type and the original *** the ring-type Wells turbine with fixed guide vanes shows the best performance with the maximal efficiency of 0.55,which is 22% higher than that of the original *** addition,the quasi-steady analysis is used to calculate the mean efficiency and output-work of a wave cycle under sinusoidal flow *** all together,this study provides support for structural optimization of impulse turbine and Wells turbine in the future.

关键词： OWC impulse turbine Wells turbine CFD endplate ring quasi-steady analysis

Construction of metal-organic frameworks with unsaturated Cu sites for efficient and fast reduction of nitroaromatics:A combined experimental and theoretical study

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Chinese Chemical Letters 2024年第8期35卷 514-519页

作者： Longlong Geng Huiling Liu Wenfeng Zhou Yong-Zheng Zhang Hongliang Huang Da-Shuai Zhang Hui Hu Chao Lv Xiuling Zhang Suijun Liu Shandong Provincial Key Laboratory of Monocrystalline Silicon Semiconductor Materials and Technology College of Chemistry and Chemical EngineeringDezhou UniversityDezhou 253023China School of Chemistry and Chemical engineering Shandong University of TechnologyZibo 255000China State Key Laboratory of Separation Membranes and Membrane Processes School of Chemical Engineering and TechnologyTiangong UniversityTianjin 300387China School of Chemistry and Chemical engineering Jiangxi Provincial Key Laboratory of Functional Molecular Materials ChemistryJiangxi University of Science and TechnologyGanzhou 341000China

Metal-organic frameworks(MOFs)functionalized with open metal sites(OMSs)have received widespread attention in various applications due to their fascinating electronic properties and unique interactions with guest ***,rational tailoring of the coordination environment of metal nodes dur-ing the synthesis of MOFs remains a great challenge due to their tendency of saturated coordination with ***,we reported the construction of three new MOFs featuring unsaturated Cu(Ⅱ)sites,namely[Cu(HCOO)(pzta)]_(n)(HL-1),{[Cu(PTA)0.5(pzta)(H_(2)O)]·2H_(2)O}_(n)(HL-2)and[Cu(NA)0.5(pzta)]_(n)(HL-3)(Hpzta=3-pyrazinyl-1,2,4-triazole;PTA=terephthalic acid;NA=1,4-naphthalene dicarboxylic acid),based on the mixed-linker strategy via specific selection of versatile Hpzta ligand and carboxylate ***-markably,the obtained MOFs exhibited excellent activity and good recyclability for the catalytic reduction of nitroaromatics under mild conditions(25℃and 1 atm).In particular,the complete conversion of 4-nitrophenol(4-NP)took only 30 s on HL-2,reaching a record-high TOF value compared with previously reported metal *** combined experimental and theoretical studies on HL-2 revealed that the open Cu site with positive-charged nature could improve the adsorption and subsequent electron trans-port between the substrates,and was responsible for the outstanding *** work shined lights on the further enhancement of performance for MOFs through rational OMSs construction.

关键词： Metal-organic frameworks Open metal sites Catalysis Copper node 4-Nitrophenol

Effect of Co on oxidation and hot corrosion behavior of two nickel-based superalloys under Na_(2)SO_(4)-NaCl at 900℃

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Transactions of Nonferrous Metals Society of China 2021年第8期31卷 2402-2414页

作者： Jun-sheng MENG Ming-xuan CHEN Xiao-ping SHI Qiang MA naval architecture and port engineering college Shandong Jiaotong UniversityWeihai 264200China

Nickel-based superalloys with and without Co by partial replacement of W were prepared using double vacuum melting.A comparison of the oxidation in air and hot corrosion behaviors under molten 75 wt.%Na2 SO4+25 wt.%NaCl at 900℃were systematically *** results showed that partial replacement of W with Co promoted the formation of chromia scale and consequently decreased the oxidation ***,the addition of Co also retarded the internal oxidation/nitridation of Al and consequently promoted the growth of Al_(2) O3 scale,which further decreased the scaling rate and improved the adhesion of ***,the addition of Co also further improved the hot corrosion resistance under molten Na2 SO4-NaCl salts.

关键词： nickel based superalloys oxidation hot corrosion spallation resistance

Prediction of Non-Cavitation Propeller Noise in Time Domain

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China Ocean engineering 2011年第3期25卷 531-538页

作者：叶金铭熊鹰肖昌润毕毅 college of naval architecture and Power Naval University of Engineering The Ministry of Education Key Laboratory of High Speed Ship engineering Wuhan University of Technology

The blade frequency noise of non-cavitation propeller in a uniform flow is analyzed in time domain. The unsteady loading （dipole source） on the blade surface is calculated by a potential-based surface panel method. Then the time- dependent pressure data is used as the input for Ffowcs Williams-Hawkings formulation to predict the acoustics pressure. The integration of noise source is performed over the true blade surface rather than the nothickness blade surface, and the effect of hub can be considered. The noise characteristics of the non-cavitation propeller and the numerical discretization forms are discussed.

关键词： propeller surface panel method, noise time domain

Risk Analysis and Assessment of Overtopping Concerning Sea Dikes in the Case of Storm Surge

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China Ocean engineering 2014年第4期28卷 479-487页

作者：王莉萍黄桂玲陈正寿梁丙臣刘桂林 college of Mathematical Science Ocean University of China School of naval architecture and Marine engineering Zhejiang Ocean University college of engineering Ocean University of China

Risk analysis and assessment relating coastal structures has been one of the hot topics in the area of coastal protection recently. In this paper, from three aspects of joint return period of multiple loads, dike failure rate and dike continuous risk prevention respectively, three new risk analysis methods concerning overtopping of sea dikes are developed. It is worth noting that the factors of storm surge which leads to overtopping are also considered in the three methods. In order to verify and estimate the effectiveness and reliability of the newly developed methods, quantified mutual information is adopted. By means of case testing, it can be found that different prior variables might be selected dividedly, according to the requirement of special engineering application or the dominance of loads. Based on the selection of prior variables, the correlating risk analysis method can be successfully applied to practical engineering.

关键词： sea dikes risk analysis failure rate mutual information

Parameter matching and experiment of the combined cyclone separation and cylinder sieve cleaning system for rape combine harvester

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International Journal of Agricultural and Biological engineering 2024年第1期17卷 128-136页

作者： Jiacheng Yuan Qingxi Liao Xingyu Wan Jia Yang Caixia Shu college of engineering Huazhong Agricultural UniversityWuhan 430070China Key Laboratory of Agricultural Equipment in Mid-lower Yangtze River Ministry of Agriculture and Rural AffairsWuhan 430070China

Existing rape combine harvester with a cyclone separation cleaning device has the challenge that the loss rate and the cleaning rate increase and decrease simultaneously.A cleaning process route was proposed,which involves the cyclone separation cleaning device removing light and tiny impurities,and the cylinder sieve device removing coarse and long impurities such as pod shells and short stems.A novel cleaning system combining the cyclone separation cleaning device and cylinder sieve cleaning devices was *** ranges of the structure and operation parameters for each component were analyzed based on kinematics and dynamic analysis.A four-factor five-level quadratic orthogonal test was carried out,in which the loss rate and cleaning rate were taken as the evaluation *** velocity at the suction port,the rotation speed of the cylinder sieve,the screw pitch of the spiral blade and the diameter of the sieve hole were taken as the influencing *** orthogonal test results showed that the cleaning system performed best at a rotation speed of the winnower is 600 r/min,an airflow velocity at the suction port is 18.25 m/s,a rotation speed of the cylinder sieve is 87 r/min,a screw pitch of the spiral blade is 440 mm and a diameter of the sieve hole is 4.48 *** this time,the loss rate of the cleaning system is 3.22%,and the cleaning rate is 95.67%.Compared to the conventional cyclone separation cleaning device,the loss rate is reduced by 2.17%and the cleaning rate is increased by 1.05%.This study can provide a reference for the optimal cleaning system design for rape combine harvesters.

关键词： agricultural engineering cleaning system cyclone separation cylinder sieve rapeseed combine harvester