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Characteristics of Particulate Matter Emissions for Low-Sulfur Heavy Oil Used in Low-Speed Two-Stroke Diesel Engines of ocean-Going Ships

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Journal of Thermal Science 2024年第2期33卷 739-750页

作者： WU Gang MA Qianli WEI Lijiang JIANG Guohe WANG Tengfei LI Tie Merchant Marine College Shanghai Maritime UniversityShanghai201306China state key laboratory of ocean engineering Shanghai Jiao Tong UniversityShanghai200240China

In this work,particulate matter(PM) emissions from a large two-stroke,low-speed marine diesel engine were investigated when the engine was operated with low-sulfur heavy fuel oil(HFO) at various *** samples were collected in situ from the engine exhaust to determine the detailed physical and chemical *** nanostructure and morphology of the nanoparticles were analyzed using transmission electron microscopy images(TEM).The results show that volatile organic carbon(OC) accounts for more than 80% in the HFO particles and leads to an increase in particle *** thermodynamic conditions of a low-speed engine favor the behavior of capturing the soluble organic components.A large number of spherical char HFO particles with aerodynamic diameters of 0.2 μm-0.5 μm and a suspected inner metal core were *** two peak aerodynamic diameters of the HFO nanoparticles are 15 nm and 86 *** morphological differences among the HFO nanoparticles in varied engine conditions represent the formation process from primary nascent particles to mature graphitized particles caused by *** above study will be valuable for understanding the characteristics of PM emissions from low-sulfur HFO to achieve the ship PM emissions reduction target.

关键词： low-speed diesel engine maritime regulations heavy fuel oil TEM particles size and distribution

Bionic soft robotic gripper with feedback control for adaptive grasping and capturing applications

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Frontiers of Mechanical engineering 2024年第1期19卷 129-148页

作者： Tingke WU Zhuyong LIU Ziqi MA Boyang WANG Daolin MA Hexi YU Department of engineering Mechanics School of Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China state key laboratory of ocean engineering Shanghai Jiao Tong UniversityShanghai 200240China MOE key laboratory of Hydrodynamics Shanghai Jiao Tong UniversityShanghai 200240China

Robots are playing an increasingly important role in engineering *** robots have promising applications in several fields due to their inherent advantages of compliance,low density,and soft interactions.A soft gripper based on bio-inspiration is proposed in this *** analyze the cushioning and energy absorption mechanism of human fingertips in detail and provide insights for designing a soft gripper with a variable stiffness *** investigate the grasping modes through a large deformation modeling approach,which is verified through *** characteristics of the three grasping modes are quantified through testing and can provide guidance for robotics ***,the adaptability of the soft gripper is verified by grasping multi-scale and extremely soft ***,a cushioning model of the soft gripper is proposed,and the effectiveness of cushioning is verified by grasping extremely sharp objects and living ***,we validate the advantages of the variable stiffness of the soft gripper,and the results show that the soft robot can robustly complete assemblies with a gap of only 0.1 *** to the unstructured nature of the engineering environment,the soft gripper can be applied in complex environments based on the abovementioned experimental ***,we design the soft robotics system with feedback capture based on the inspiration of human catching *** feasibility of engineering applications is initially verified through fast capture experiments on moving *** design concept of this robot can provide new insights for bionic machinery.

关键词： soft bionic gripper variable stiffness structure large deformation modeling feedback control soft robotic system

Experimental investigation on the permeability of gap-graded soil due to horizontal suffusion considering boundary effect

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Journal of Rock Mechanics and Geotechnical engineering 2024年第3期16卷 1072-1084页

作者： Xuwei Wang Yeshuang Xu state key laboratory of ocean engineering School of Naval ArchitectureOceanand Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China shanghai key laboratory for Digital Maintenance of Buildings and Infrastructure Department of Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

The boundary condition is a crucial factor affecting the permeability variation due to *** experimental investigation on the permeability of gap-graded soil due to horizontal suffusion considering the boundary effect is conducted,where the hydraulic head difference(DH)varies,and the boundary includes non-loss and soil-loss *** samples are filled into seven soil storerooms connected in *** evaluation,the variation in content of fine sand(ΔR_(f))and the hydraulic conductivity of soils in each storeroom(C_(i))are *** the non-loss test,the soil sample filling area is divided into runoff,transited,and accumulated areas according to the negative or positive ΔR_(f) values.ΔR_(f) increases from negative to positive along the seepage path,and Ci decreases from runoff area to transited area and then rebounds in accumulated *** the soil-loss test,all soil sample filling areas belong to the runoff area,where the gentle-loss,strengthened-loss,and alleviated-loss parts are further divided.ΔR_(f) decreases from the gentle-loss part to the strengthened-loss part and then rebounds in the alleviated-loss part,and C_(i) increases and then decreases along the seepage *** relationship between ΔR_(f) and Ci is different with the boundary *** exponentially decreases with ΔR_(f) in the non-loss test and increases with ΔR_(f) generally in the soil-loss test.

关键词： Suffusion Permeability Experimental investigation Boundary effect Horizontal seepage

Investigation of stress-induced progressive failure of mine pillars using a Voronoi grain-based breakable block model

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International Journal of Mining Science and Technology 2024年第5期34卷 713-729页

作者： Shili Qiu Shirui Zhang Quan Jiang Shaojun Li Hao Zhang Qiankuan Wang state key laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China university of Chinese Academy of Sciences Beijing 100049China state key laboratory of ocean engineering Shanghai Jiao Tong UniversityShanghai 200240China

The Voronoi grain-based breakable block model(VGBBM)based on the combined finite-discrete element method(FDEM)was proposed to explicitly characterize the failure mechanism and predict the deformation behavior of hard-rock mine *** influence of the microscopic parameters on the macroscopic mechanical behavior was investigated using laboratory-scale *** field-scale pillar models(width-to-height,W/H=1,2 and 3)were calibrated based on the empirically predicted stress-strain curves of Creighton mine *** results indicated that as the W/H ratios increased,the VGBBM effectively predicted the transition from strain-softening to pseudo-ductile behavior in pillars,and explicitly captured the separated rock slabs and the V-shaped damage zones on both sides of pillars and conjugate shear bands in core zones of *** volumetric strain field revealed significant compressional deformation in core zones of *** the peak strains of W/H=1 and 2 pillars were relatively consistent,there were significant differences in the strain energy storage and release mechanism.W/H was the primary factor influencing the deformation and strain energy in the pillar *** friction coefficient of the structural plane was also an important factor affecting the pillar strength and the weakest discontinuity *** fracture surface was controlled by the discontinuity angle and the friction *** study demonstrated the capability of the VGBBM in predicting the strengths and deformation behavior of hard-rock pillars in deep mine design.

关键词： Pillar strength FDEM Voronoi tessellation Spalling Bulking

Is a direct numerical simulation(DNS)of Navier-Stokes equations with small enough grid spacing and time-step definitely reliable/correct?

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Journal of ocean engineering and Science 2024年第3期9卷 293-310页

作者： Shijie Qin Yu Yang Yongxiang Huang Xinyu Mei Lipo Wang Shijun Liao School of ocean and Civil engineering Shanghai Jiao Tong UniversityShanghai 200240China state key laboratory of Marine Environmental Science College of Ocean and Earth SciencesXiamen UniversityXiamen 361102China UM-SJTU Joint Institute Shanghai Jiao Tong UniversityShanghai 200240China state key laboratory of ocean engineering Shanghai 200240China

Turbulence is strongly associated with the vast majority of fluid flows in nature and ***,results given by the direct numerical simulation(DNS)of Navier-Stokes(NS)equations that relate to a famous millennium problem are widely regarded as‘reliable’benchmark solutions of turbulence,as long as grid spacing is fine enough(*** than the minimum Kolmogorov scale)and time-step is small enough,say,satisfying the Courant-Friedrichs-Lewy condition(Courant number<1).Is this really true?In this paper a two-dimensional sustained turbulent Kolmogorov flow driven by an external body force governed by the NS equations under an initial condition with a spatial symmetry is investigated numerically by the two numerical methods with detailed comparisons:one is the traditional DNS,the other is the‘clean numerical simulation’(CNS).In theory,the exact solution must have a kind of spatial symmetry since its initial condition is spatially ***,it is found that numerical noises of the DNS are quickly enlarged to the same level as the‘true’physical solution,which finally destroy the spatial symmetry of the flow *** other words,the DNS results of the turbulent Kolmogorov flow governed by the NS equations are badly polluted *** the contrary,the numerical noise of the CNS is much smaller than the‘true’physical solution of turbulence in a long enough interval of time so that the CNS result is very close to the‘true’physical solution and thus can remain symmetric,which can be used as a benchmark solution for ***,it is found that numerical noise as a kind of artificial tiny disturbances can lead to huge deviations at large scale on the two-dimensional Kolmogorov turbulence governed by the NS equations,not only quantitatively(even in statistics)but also qualitatively(such as spatial symmetry of flow).This highly suggests that fine enough spatial grid spacing with small enough time-step alone could not guarantee the validity of the DNS of

关键词： Kolmogorov flow Statistical stability Computational reliability Clean numerical simulation Artificial numerical noises

Optimization of Band Gap of 1D Elastic Metamaterial Under Impact Load by Regulating Stiffness

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Acta Mechanica Solida Sinica 2024年第1期37卷 148-154页

作者： Tong Li Xianlong Jin Yongqiang Li Peizhong Yang School of Mechanical engineering Shanghai Jiao Tong UniversityShanghai 200240China state key laboratory of Mechanical System and Vibration Shanghai Jiaotong UniversityShanghai 200240China College of Science Northeastern UniversityShenyang 110819China

Designing materials that mitigate impacts effectively are crucial for protecting people and ***,a single-resonator metamaterial with negative mass characteristics is proposed for impact mitigation,and numerical analysis of wave propagation shows explicitly how the spring stiffness and number of unit cells influence that *** results show clearly that a metamaterial with differing microstructural stiffness is better at mitigating the effect of a shock wave than one with a unique ***,there is a critical number of unit cells beyond which the shock wave is not attenuated further,but the fabrication complexity *** the 40 groups of microstructural regions in this example,the attenuation effect no longer increases when there are more than 35 *** work offers guidance for microstructure designs in metamaterials and provides new ideas for using metamaterials to mitigate shock waves.

关键词： Elastic metamaterials Wave attenuation Stiffness Number of unit cells

Widespread and active piezotolerant microorganisms mediate phenolic compound degradation under high hydrostatic pressure in hadal trenches

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Marine Life Science & Technology 2024年第2期6卷 331-348页

作者： Hao Ling Yongxin Lv Yu Zhang Ning‑Yi Zhou Ying Xu state key laboratory of Microbial Metabolism Joint International Research Laboratory of Metabolic and Developmental Sciences and School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghai 200240China School of oceanography Shanghai Jiao Tong UniversityShanghai 200240China state key of laboratory of ocean engineering Shanghai Jiao Tong UniversityShanghai 200240China

Phenolic compounds,as well as other aromatic compounds,have been reported to be abundant in hadal *** high-throughput sequencing studies have hinted at the potential of hadal microbes to degrade these compounds,direct microbiological,genetic and biochemical evidence under in situ pressures remain ***,a microbial consortium and a pure culture of Pseudomonas,newly isolated from Mariana Trench sediments,efficiently degraded phenol under pressures up to 70 and 60 MPa,respectively,with concomitant increase in *** analyzing a high-pressure(70 MPa)culture metatranscriptome,not only was the entire range of metabolic processes under high pressure generated,but also genes encod-ing complete phenol degradation via ortho-and meta-cleavage pathways were *** isolate of Pseudomonas also contained genes encoding the complete degradation *** transcribed genes(dmpKLMNOP_(sed))were functionally identified to encode a multicomponent hydroxylase catalyzing the hydroxylation of phenol and its methylated derivatives by heterogeneous *** addition,key catabolic genes identified in the metatranscriptome of the high-pressure cultures and genomes of bacterial isolates were found to be all widely distributed in 22 published hadal microbial *** microbiological,genetic,bioinformatics,and biochemical levels,this study found that microorganisms widely found in hadal trenches were able to effectively drive phenolic compound degradation under high hydrostatic *** information will bridge a knowledge gap concerning the microbial aromatics degradation within hadal trenches.

关键词： Hadal trench High hydrostatic pressure Phenolic compounds degradation Piezotolerant microorganisms Widespread distribution

Numerical and experimental study of the effects of wind turbine operation on sand-dust transport characteristics

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Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 97-113页

作者： Gaosheng Ma Hong Han Ye Li Deshun Li Yan Wang Ning Fu Quan Zheng Rennian Li School of Energy and Power engineering Lanzhou University of TechnologyLanzhou 730050China Gansu Provincial Technology Center for Wind Turbines Lanzhou 730050China key laboratory of Fluid Machinery and Systems Lanzhou 730050China Multiple Function Towing Tank laboratory State Key Laboratory of Ocean EngineeringSchool of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Given factors such as reduced land availability for onshore wind farms,wind resource enrichment levels,and costs,there is a growing trend of establishing wind farms in deserts,the Gobi,and other arid ***,the relationship between sanddust weather environments and wind turbine operations has garnered significant *** investigate the impact of wind turbine wakes on sand-dust transportation,this study employs large eddy simulation to model flow fields,coupled with an actuator line model for simulating rotating blades and a multiphase particle in cell model for simulating sand *** research focuses on a horizontal axis wind turbine model and examines the motion and spatiotemporal distribution characteristics of four typical sizes of sand particles in the turbine *** findings reveal that sand particles of varying sizes exhibit a spiral settling pattern after traversing the rotating plane of wind turbine blades,influenced by blade shedding vortex and *** particles tend to cluster in the peripheries of the vortex cores of low vorticity in the wind turbine *** rotation of wind turbines generates a wake vortex structure that causes a significant clustering of sand particles at the tip *** the wake distance increases,the particles that cluster at the turbine's tip gradually spread outward to approximately twice the rotor diameter and then begin to mix with the incoming flow *** turbines have a noticeable impact on sand-dust transportation,hindering their movement to a significant *** average sand-blocking rate exhibits a trend of initially increasing and then decreasing as the wake distance *** its peak,the sand-blocking rate reaches an impressive 67.55%.The presence of wind turbines induces the advanced settling of sand particles,resulting in a“triangular”distribution of the deposition within the ground projection area of the wake.

关键词： wind turbine particle transportation actuator line model dry deposition particle clustering

Deep learning methods for roping defect analysis in aluminum alloy sheets: prediction and grading

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Advances in Manufacturing 2024年第3期12卷 576-590页

作者： Yuan-Zhe Hu Ru-Xue Liu Jia-Peng He Guo-Wei Zhou Da-Yong Li state key laboratory of Mechanical Systems and Vibration Shanghai Jiao Tong UniversityShanghai200240People’s Republic of China School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240People’s Republic of China

Roping is a severe band-like surface defect that occurs in deformed aluminum alloy *** roping prediction and rating are essential for industrial ***,the authors introduced an artificial neural network(ANN)model to efficiently forecast roping behavior across the thickness of large regions with texture *** this study,the previously proposed ANN model for roping prediction is briefly reviewed,and a few-shot learning(FSL)-based method is developed for roping grading with limited *** consider the directionality of the roping patterns,the roping dataset constructed from experimental observations is transformed into the frequency domain for more compact characterization.A transfer-based FSL method is further presented for grade roping with manifold mixup regularization and the Sinkhorn mapping algorithm.A new component-focused representation is also implemented for data-processing,exploiting the close correlation between roping and power distribution in the frequency *** ultimate FSL method achieved an optimal accuracy of 95.65%in roping classification with only five training samples per class,outperforming four typical FSL *** FSL approach can be applied to grade the roping morphologies predicted by the ANN ***,the combination of prediction and grading using deep learning provides a new paradigm for roping analysis and control.

关键词： Roping Artificial neural network(ANN) Aluminum alloys Few-shot classification Surface morphology