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A Novel Extremum Seeking Control to Enhance Convergence and Robustness in the Presence of Nonlinear Dynamic Sensors

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Journal of Systems Science & Complexity 2024年第1期37卷 3-21页

作者： LIU Hengchang TAN Ying OETOMO Denny School of Electrical Mechanical and Infrastructure EngineeringThe University of MelbourneParkville VIC 3010Australia

This paper focuses on optimizing an unknown cost function through extremum seeking(ES)control in the presence of a slow nonlinear dynamic sensor responsible for measuring the *** contrast to traditional perturbation-based ES control,which often suffers from sluggish convergence,the proposed method eliminates the time-scale separation between sensor dynamics and ES control by using the relative degree of the nonlinear sensor *** improve the convergence rate,the authors incorporate high-frequency dither signals and a *** enhance the robustness with the existence of rapid disturbances,an off-the-shelf linear high-gain differentiator is *** first result demonstrates that,for any desired convergence rate,with properly tuned parameters for the proposed ES algorithm,the input of the cost function can converge to an arbitrarily small neighborhood of the optimal solution,starting from any initial condition within any given compact ***,the second result shows the robustness of the proposed ES control in the presence of sufficiently fast,zero-mean periodic *** results substantiate these theoretical findings.

关键词： Averaging extremum seeking optimization singular perturbation time-scale separation

Modifying effects and mechanisms of superfine stainless wires on microstructures and mechanical properties of ultra-high performance seawater sea-sand concrete

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Science China Technological Sciences 2024年第10期67卷 3205-3220页

作者： YU Feng DONG SuFen ASHOUR Ashraf DING SiQi HAN BaoGuo School of infrastructure engineering Dalian University of Technology Faculty of engineering & Informatics University of Bradford department of Civil and Environmental engineering The Hong Kong Polytechnic University

Ultra-high-performance seawater sea-sand concrete（UHPSSC） presents a prospective solution to address the natural resource shortage in marine infrastructure construction. To eliminate the corrosion risk of steel fibers and broaden the applicability of UHPSSC, this study investigates the mechanical properties and free chloride ion content as well as microstructures of UHPSSC reinforced with superfine stainless wires（SSWs） under natural curing. The results indicate that 1.5% SSWs can remarkably improve the flexural strength and toughness of UHPSSC by 127% and 1724%, respectively, and mitigate the long-term strength degradation of UHPSSC. The strong interfacial bond between SSW and UHPSSC improves the compactness of UHPSSC, thus reducing the growth space for Ca（OH）2crystals and swelling hydration products generated by sulfate and magnesium ions. This can be supported by the observed reduction in the Ca/Si ratio of C–S–H gels, CH crystal orientation index, and ***, through mechanisms such as pull-out, rupture, overlapping network, and internal anchor interface, SSWs effectively prevent microcrack growth and propagation, transforming single long-connected microcracks into multiple-emission microcracks centered on SSW. Additionally, the free chloride ion content of the composites at 28 and 180 d meets the ACI 318-19 standard requirements for concrete exposed to seawater. This compliance is attributed to the chloride immobilization facilitated by Friedel's salt and C–S–H gels within the interfaces around SSWs and sea-sand. Consequently, SSWs-reinforced UHPSSC exhibits considerable potential for applications in sustainable marine infrastructures, demanding long-term mechanical properties and high durability.

关键词： ultra-high performance seawater sea-sand concrete superfine stainless wire mechanical properties chloride ion content microstructure

A CFD study on the hydrodynamic response of a small-scale ice floe induced by a passing ship

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Journal of Hydrodynamics 2024年第2期36卷 290-299页

作者： Zongyu Jiang Spyros Hirdaris Sasan Tavakoli Mikko Suominen Pentti Kujala Marine and Arctic Technology Department of Mechanical EngineeringAalto UniversityEspooFinland Global Ship Systems Centre ABS Hellenic SM LLC.AthensGreece department of infrastructure engineering The University of MelbourneMelbourneAustralia

A Reynolds averaged Navier-Stokes(RANS)computational fluid dynamics(CFD)model is built to investigate the hydrodynamic response of a circular ice floe under the influence of a passing ship in calm *** ship,mirroring the KRISO Container Ship’s hull design,progresses near an ice floe whose diameter is 30%of the ship’s length and its thickness is 3 *** ship advances at a constant speed,which is handled by using the overset mesh *** study focuses on the ice floe’s motions and the hydrodynamic forces induced by three speeds and three transverse distances of the passing *** reveal that ship-generated wakes notably influence the ice floe’s motions,with a greater influence on sway than ***,the ship’s speed and proximity distinctly affect the ice floe’s motions.

关键词： Hydrodynamics ship-ice interactions ice floe Reynolds averaged Navier-Stokes(RANS)computational fluid dynamics(CFD)

Dewatering of Scenedesmus obliquus Cultivation Substrate with Microfiltration:Potential and Challenges for Water Reuse and Effective Harvesting

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engineering 2024年第7期38卷 155-163页

作者： Marco Malaguti Lorenzo Craveri Francesco Ricceri Vincenzo Riggio Mariachiara Zanetti Alberto Tiraferri department of Environment Land and Infrastructure EngineeringPolitecnico di TorinoTorino 10129Italy Clean Water Center Politecnico di TorinoTorino 10129Italy

In the microalgae harvesting process,which includes a step for dewatering the algal suspension,directly reusing extracted water in situ would decrease the freshwater footprint of cultivation *** various algae harvesting techniques,membrane-based filtration has shown numerous *** study evaluated the reuse of permeate streams derived from Scenedesmus obliquus(***)biomass filtration under bench-scale and pilot-scale *** particular,this study identified a series of challenges and mechanisms that influence the water reuse potential and the robustness of the membrane harvesting *** a preliminary phase of this investigation,the health status of the initial biomass was found to have important implications for the harvesting performance and quality of the permeate stream to be reused;healthy biomass ensured better dewatering performance(i.e.,higher water fluxes)and higher quality of the permeate water streams.A series of bench-scale filtration experiments with different combinations of cross-flow velocity and pressure values were performed to identify the operative conditions that would maximize water *** selected conditions,2.4 m·s^(-1)and 1.4 bar(1 bar=105 Pa),respectively,were then applied to drive pilot-scale microfiltration tests to reuse the collected permeate as a new cultivation medium for *** growth in a pilot-scale *** investigation revealed key differences between the behavior of the membrane systems at the two scales(bench and pilot).It indicated the potential for beneficial reuse of the permeate stream as the pilot-scale experiments ensured high harvesting performance and growth rates of biomass in permeate water that were highly similar to those recorded in the ideal cultivation ***,different nutrient reintegration protocols were investigated,revealing that both macro-and micro-nutrient levels are critical for the success of the reuse approach.

关键词： Scenedesmus obliquus Microfiltration Permeate reuse Harvesting Microalgae Pilot-scale

Frost deformation and microstructure evolution of porous rock under uniform and unidirectional freeze-thaw conditions

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Journal of Mountain Science 2024年第8期21卷 2855-2869页

作者： LV Zhitao LIU Jintao WAN Ling LIU Weiping School of infrastructure engineering Nanchang UniversityNanchang 330031China College of Civil engineering and Architecture Nanchang Hangkong UniversityNanchang 330063China

The frost deterioration and deformation of porous rock are commonly investigated under uniform freeze-thaw(FT)***,the unidirectional FT condition,which is also prevalent in engineering practice,has received limited ***,a comparative study on frost deformation and microstructure evolution of porous rock under both uniform and unidirectional FT conditions was ***,frost deformation experiments of rock were conducted under cyclic uniform and unidirectional FT action,*** illustrate that frost deformation of saturated rock exhibits isotropic characteristics under uniform FT cycles,while it shows anisotropic characteristics under unidirectional FT condition with both the frost heaving strain and residual strain along FT direction much higher than those perpendicular to FT ***,the peak value and residual value of cumulative frost strain vary as logarithmic functions with cycle number under both uniform and unidirectional FT ***,the microstructure evolution of rock suffered cyclic uniform and unidirectional FT action were *** uniform FT cycles,newly generated pores uniformly distribute in rock and pore structure of rock remains isotropic in micro scale,and thus the frost deformation shows isotropic characteristics in macro *** unidirectional FT cycles,micro-cracks or pore belts generate with their orientation nearly perpendicular to the FT direction,and rock structure gradually becomes anisotropic in micro scale,resulting in the anisotropic characteristics of frost deformation in macro scale.

关键词： Frost deformation Microstructure evolution Porous rock Unidirectional freeze-thaw cycles Uniform freeze-thaw cycles

Parametric study on contact sensors for MASW measurement-based interfacial debonding detection for SCCS

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Earthquake engineering and engineering Vibration 2024年第2期23卷 331-344页

作者： Chen Hongbing Pang Xin Gan Shiyu Li Yuanyuan Gokarna Chalise Nie Xin Research Institute of Urbanization and Urban Safety School of Civil and Resource EngineeringUniversity of Science and Technology BeijingBeijing 100083China department of Civil engineering Tsinghua UniversityBeijing 100084China Faculty of infrastructure engineering Dalian University of TechnologyDalian 116081China

Steel-concrete composite structures(SCCS)have been widely used as primary load-bearing components in large-scale civil *** the basis of the co-working ability of steel plate and concrete,the bonding status plays an essential role in guaranteeing the structural performance of ***,efficient non-destructive testing(NDT)on interfacial debondings in SCCS has become a prominent research ***-channel analysis of surface waves(MASW)has been validated as an effective NDT technique for interfacial debonding detection for ***,the feasibility of MASW must be validated using experimental *** study establishes a high-frequency data synchronous acquisition system with 32 channels to perform comparative verification experiments in ***,the current sensing approaches for high-frequency vibration and stress waves are ***,three types of contact sensors,namely,piezoelectric lead-zirconate-titanate(PZT)patches,accelerometers,and ultrasonic transducers,are selected for MASW ***,the selection and optimization of the force hammer head are *** experiments are carried out for the optimal selection of ultrasonic transducers,PZT patches,and accelerometers for MASW *** addition,the influence of different pasting methods on the output signal of the sensor array is *** results indicate that optimized PZT patches,acceleration sensors,and ultrasonic transducers can provide efficient data acquisition for MASW-based non-destructive *** research findings in this study lay a solid foundation for analyzing the recognition accuracy of contact MASW measurement using different sensor arrays.

关键词： steel-concrete composite structures(SCCS) interface debonding detection multi-channel analysis of surface waves(MASW) sensor selection comparative experimental study

Prediction of maximum upward displacement of shield tunnel linings during construction using particle swarm optimization-random forest algorithm

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2024年第1期25卷 1-17页

作者： Xiaowei YE Xiaolong ZHANG Yanbo CHEN Yujun WEI Yang DING MOE Key Laboratory of Soft Soils and Geoenvironmental engineering Zhejiang UniversityHangzhou310058China department of Civil engineering Zhejiang UniversityHangzhou310058China Zhejiang engineering Research Center of Intelligent Urban infrastructure Hangzhou City UniversityHangzhou310015China

During construction,the shield linings of tunnels often face the problem of local or overall upward movement after leaving the shield tail in soft soil areas or during some large diameter shield *** floating will increase the initial stress on the segments and bolts which is harmful to the service performance of the *** this study we used a random forest(RF)algorithm combined particle swarm optimization(PSO)and 5-fold cross-validation(5-fold CV)to predict the maximum upward displacement of tunnel linings induced by shield tunnel *** mechanism and factors causing upward movement of the tunnel lining are comprehensively *** input variables were selected according to results from analysis of influencing *** prediction performance of two models,PSO-RF and RF(default)were *** Gini value was obtained to represent the relative importance of the influencing factors to the upward displacement of *** PSO-RF model successfully predicted the maximum upward displacement of the tunnel linings with a low error(mean absolute error(MAE)=4.04 mm,root mean square error(RMSE)=5.67 mm)and high correlation(R^(2)=0.915).The thrust and depth of the tunnel were the most important factors in the prediction model influencing the upward displacement of the tunnel linings.

关键词： Random forest(RF) Particle swarm optimization(PSO) Upward displacement of lining Machine learning prediction Shieldtunneling construction

Detection of internal crack growth in polyethylene pipe using guided wave ultrasonic testing

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Earthquake engineering and engineering Vibration 2024年第2期23卷 319-329页

作者： Jay Kumar Shah Hao Wang Said El-Hawwat Centre of Advanced infrastructure and Transportation RutgersThe State University of New JerseyNJ 08854USA department of Civil and Environmental engineering RutgersThe State University of New JerseyNJ 08854USA

Despite the success of guided wave ultrasonic inspection for internal defect detection in steel pipes,its application on polyethylene(PE)pipe remains relatively *** growth of internal cracks in PE pipe severely affects its pressure-holding capacity,hence the early detection of internal cracks is crucial for effective pipeline maintenance *** study extends the scope of guided wave-based ultrasonic testing to detect the growth of internal cracks in a natural gas distribution PE *** experiments and a finite element model were planned to study the wave-crack interaction at different stages of axially oriented internal crack growth with a piezoceramic transducer-based setup arranged in a pitch-catch *** dispersion analysis supplemented with preliminary experiments was performed to isolate the optimal inspection frequency,leading to the selection of the T(0,1)mode at 50-kHz for the investigation.A transmission index based on the energy of the T(0,1)mode was developed to trace the extent of simulated crack *** findings revealed an inverse linear correlation between the transmission index and the crack depth for crack growth beyond 20%crack depth.

关键词： polyethylene pipes internal cracks guided wave ultrasonic testing torsional modes finite element modeling

Spatiotemporal variations of sand hydraulic conductivity by microbial application methods

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Journal of Rock Mechanics and Geotechnical engineering 2024年第1期16卷 268-278页

作者： Viroon Kamchoom Thiti Khattiwong Treesukon Treebupachatsakul Suraparb Keawsawasvong Anthony Kwan Leung Excellent Centre for Green and Sustainable infrastructure Department of Civil EngineeringSchool of EngineeringKing Mongkut’s Institute of Technology Ladkrabang(KMITL)Bangkok10520Thailand department of Biomedical engineering School of EngineeringKing Mongkut’s Institute of Technology Ladkrabang(KMITL)Bangkok10520Thailand department of Civil engineering Thammasat School of EngineeringThammasat UniversityPrathumthani10200Thailand department of Civil and Environmental engineering The Hong Kong University of Science and Technology(HKUST)Hong KongChina

The spatiotemporal distributions of microbes in soil by different methods could affect the efficacy of the microbes to reduce the soil hydraulic *** this study,the specimens of bio-mediated sands were prepared using three different methods,***,mixing,and pouring a given microbial so-lution onto compacted sand *** hydraulic conductivity was measured by constant-head tests,while any soil microstructural changes due to addition of the microbes were observed by scan-ning electron microscope(SEM)and mercury intrusion porosimetry(MIP)*** amount of dextran concentration produced by microbes in each type of specimen was quantified by a *** show that dextran production increased exponentially after 5-7 d of microbial settling with the supply of culture *** injection and mixing methods resulted in a similar amount and uniform dis-tribution of dextran in the *** pouring method,however,produced a nonuniform distri-bution,with a higher concentration near the specimen *** the supply of culture medium discontinued,the dextran content near the surface produced by the pouring method decreased dramatically due to high competition for nutrients with foreign *** dextran concentration was negatively and correlated with hydraulic conductivity of bio-mediated soils exponentially,due to the clogging of large soil pores by *** hydraulic conductivity of the injection and mixing cases did not change significantly when the supply of culture medium was absent.

关键词： Bio-mediated soil Dextran Hydraulic conductivity Leuconostoc mesenteroides Microbial application Microstructure