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The Optimization Design of the Nozzle Section for theWater Jet Propulsion System Applied in Jet Skis

Computer Modeling in engineering & Sciences 2024年第3期138卷 2277-2304页

作者： Cheng-Yeh Li Jui-Hsiang Kao Department of Systems Engineering and Naval Architecture Taiwan Ocean UniversityKeelungTaiwanChina

The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and ***,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limited by stern *** entire section,from the rotor to the nozzle through the stator,must be designed based on system integration in that the individual performance of these three components will influence each ***,the section from the rotor to the nozzle significantly impacts the performance of a water jet propulsion *** study focused on nozzle design and established referable analysis results to facilitate subsequent integrated studies on the design parameters regarding nozzle *** existing studies concentrate on discussions on rotor design and the tip leakage flow of rotors or have replaced the existing complex computational domain with a simple flow ***,research has yet to implement an integrated,optimal design of the section from the rotor to the *** the above,our program conducted preliminary research on this system integration design issue,discussed the optimal nozzle for this section in-depth,and proposed design suggestions based on the *** program used an existing model as the design *** study referred to the actual trial data as the design conditions for the proposed *** prior references’simple flow field form,this study added a jet ski geometry and free surface to the computational *** the linear hull shape was considered,the inflow in the inlet duct would be closer to the actual *** on the numerical calculation result,this study recommends that the optimal nozzle outlet area should be 37%of the inlet area and that the nozzle contour should be ***,for the pump head,static pressure had a more significant impact than dynamic pressure.

关键词： Water jet propulsion system rotor nozzle outlet area nozzle contour

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Structure-borne noise of steel and concrete box girders in an urban metro system: A hybrid evaluation and parametric study

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Journal of Low Frequency Noise Vibration and Active Control 2023年第4期42卷 1560-1577页

作者： Hsu, W.L. Department of Systems Engineering and Naval Architecture National Taiwan Ocean University Keelung Taiwan

Metro systems provide an efficient, convenient, and expeditious way to travel around crowded routes. Because these systems are established in cities, residential buildings close to metro viaducts are significantly affected by structure-borne noise (SBN). Although most previous studies developed SBN prediction with a focus on the accuracy and computational efficiency of a specific bridge type, only limited studies on parameters for the SBN on bridges were carried out. Thus, eliminating SBN is still a challenging task for both the design and operation phases of bridge design. Therefore, this study integrates simplified experiments with numerical analyses to evaluate the influential parameters on the structure-borne noise level (SBNL) for two types of bridge girders, that is, the double-box pre-stressed concrete girder and the double-box steel girder. The present study also proposes an optimization method for reducing the SBNL in the bridge design and operation phases and identifies the sources of SBN for these two types of bridges. In this paper, the solutions to mitigating SBN are first reviewed and briefly introduced. Theories associated with SBN are then derived and experimentally verified using a concrete or steel plate with a unit area. A hybrid evaluation method is developed to integrate transient finite-element simulation with experimental results, and the main sources (e.g., plate thickness, train speed, fastener stiffness, and track irregularity) that induce SBN are examined by this hybrid method. Consequently, the approach to resolving the SBN problem can be optimally determined. As demonstrated in the results from the hybrid evaluation method, the track condition dominates the SBNL for both types of bridges, and the relationship between train speed and plate eigenfrequency should be carefully investigated to avoid the effect of plate resonance. The pre-stressed concrete box girder is the recommended bridge type for use in urban areas from the viewpoint of m

关键词： Finite element method

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Collision Avoidance Method for USVs Based on the Artificial Potential Field and Elliptical Ship Domain

Collision Avoidance Method for USVs Based on the Artificial ...

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2025 IEEE Underwater Technology, UT 2025

作者： Chen, Youquan Huang, Shen-Wei Weng, Wei-Chu National Taiwan Ocean University Department of Systems Engineering and Naval Architecture Keelung Taiwan

ISBN: (纸本)9798331534189

With the rapid development of unmanned vehicle technology, the shipping industry is facing increasingly severe navigation safety challenges. The significant increase in the number of ships at sea has made ports and waterways more congested. To address this, the International Maritime Organization has formulated the COLREGs to promote coordination and consensus in collision avoidance processes. However, approximately 80% of maritime accidents are caused by human error, highlighting the importance of developing unmanned surface vehicles (USVs). USVs can not only assist tugboats and pilots with boarding operations but also reduce the risk of human error. The APF method has been widely applied in collision avoidance technology for unmanned vehicles. APF technology transforms navigation into a potential field model, allowing ships to autonomously avoid obstacles. However, the traditional artificial potential field method often results in longer collision avoidance paths in dynamic environments or high-density navigation areas, thereby increasing risk. To solve this problem, this paper proposes an improved method based on the artificial potential field to guide ship collision avoidance. This method creates an elliptical field at the collision point of two ships. As the distance between the own ship and the collision point decreases, the semi-minor axis of the elliptical field lengthens. An attractive point is set at the edge of the semi-minor axis. The attractive force generated by this point and the repulsive force generated by the collision point overlap, forming a resultant force to guide the ship in collision avoidance. Compared to the traditional artificial potential field method without an attractive point, the improved method proposed in this work can reduce the collision avoidance path length by 12-24%. Most importantly, this method complies with COLREGs regulations, enabling quick alignment with existing ship collision avoidance rules and ensuring consistency. Th

关键词： Unmanned surface vehicles

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Discussion of the Fluid Acceleration Quality of a Ducted Propulsion System on the Propulsive Performance

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Computer Modeling in engineering & Sciences 2022年第3期130卷 1325-1348页

作者： Jui-Hsiang Kao Yi-Fan Liao Department of Systems Engineering and Naval Architecture Taiwan Ocean UniversityKeelung202301Taiwan

This paper focuses on the ducted propulsion with the accelerating nozzle,and discusses the influence of its fluid acceleration quality on its propulsive performances,including the hull efficiency,the relative rotative efficiency,the effective wake,and the thrust deduction *** actual ducted propulsion system is used as an example for computational *** computational conditions are divided into four combinations,which are provided with different propeller pitches,cambers,and duct *** applied in this study is the Computational Fluid Dynamics(CFD)technology,and the contents of the calculation include the hull’s viscous resistance,the wave-making resistance,the propeller performance curve,and the self-propulsion simulation in order to obtain the ship’s effective wake,thrust deduction factor,hull efficiency,and relative rotative *** performance curve of the propeller and resistance estimation results are compared with the experimental values for determining the correctness of the self-propulsion *** to the computational analysis,it is known that increasing the propeller pitch cannot effectively increase the hull *** duct acceleration quality can be reduced by shortening the duct length;hence,when the effective wake fraction and thrust deduction factor decrease,the hull efficiency is *** addition,the pressure inside the duct is relatively low if the acceleration quality of the duct is too high,which is unfavorable for controlling the propeller ***,if the hull bottom in front of the propeller is tapered up from the front to the back at an overly steep angle,the thrust deduction factor will be too large and lead to a relatively low hull efficiency.

关键词： Ducted propellers accelerating nozzle hull efficiency relative rotative efficiency effective wake thrust deduction factor

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Using ROVs for Tilt Angle Measurement of Pier Foundation Piles at Pier-Type Docks

Using ROVs for Tilt Angle Measurement of Pier Foundation Pil...

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2025 IEEE Underwater Technology, UT 2025

作者： Yeh, Zeh-Yao Huang, Sheng-Wei Zhou, En-Yi Huang, Ho-Yueh National Taiwan Ocean University Department of Systems Engineering and Naval Architecture Taiwan National Taiwan University Department of Engineering Science and Ocean Engineering Taiwan

ISBN: (纸本)9798331534189

Regular inspection of pier foundation piles is essential for ensuring the structural integrity and operational safety of pier-type docks. Traditional approaches rely on divers to manually measure pile tilt angles using inclinometers, but these methods pose significant safety risks and are increasingly constrained by the dwindling availability of skilled divers. This study investigates the use of remotely operated vehicles (ROVs) equipped with advanced sonar technology as a safer, more efficient alternative for underwater pile inspections. A mini-ROV outfitted with dual-frequency forward-looking sonar (FLS) and supplementary sensors was employed, with the sonar system mounted vertically to facilitate tilt angle measurements through edge detection of sonar images. To enhance the robustness of data processing under complex underwater environments, algorithmic improvements in noise suppression and edge detection were implemented. Field experiments conducted at Xingda Harbor in Taiwan involved inspecting 65 pier foundation piles. The ROV's sonar-based measurements were compared to diver-acquired tilt angles, which served as the ground truth. Results revealed that the ROV method achieved an average error of -1.37 degrees, with final error rates remaining within 4% after compensating for ROV attitude changes. These findings confirm that the ROV-based approach delivers accuracy comparable to traditional diver methods while significantly reducing operational risks and reliance on human divers. This study underscores the potential of ROVs to revolutionize underwater inspections, offering a safe and efficient solution for real-world applications. © 2025 IEEE.

关键词： Piers

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Cyclic true stress true strain relation in the large strain region of common steel for welded structures

Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Weld...

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Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society 2023年第3期41卷 217-224页

作者： Matsuda, Kazuki Shimoka, Tsukasa Murakami, Koji Uchimura, Tomoya Gotoh, Koji Department of Marine Systems Engineering Faculty of Engineering Kyushu University Japan Department of Naval Architecture and Ocean Engineering Graduate School of Engineering Kyushu University Japan Technical Division School of Engineering Kyushu University Japan

Cyclic true stress - true strain curves were obtained using general-purpose shipbuilding steel in the large strain region. Test methods are incremental step test and static tensile test after cyclic loading. The stress-strain curves for static and cyclic loading were compared to investigate the cause of the difference between each other. A simple method for estimating the cyclic stress-strain curves was proposed. The diameter and curvature of the smallest cross-section of the specimen were measured using telecentric measurement device, and the true stress - true strain curve was obtained using the Bridgman correction method. Using the measurement method, cyclic stress-strain diagrams were obtained in the region where the true strain exceeded 1% by performing cyclic tensile tests using the incremental step method and static tensile tests after cyclic loading. The influence of the test method and maximum displacement conditions on the cyclic stress-strain curve was small within the scope of this study. There was little difference in the elongation between the static tensile test and the static tensile test after cyclic loading. The difference in yield stress between static and cyclic loading was discussed in terms of macro-yield mechanisms at intergranular and transgranular. A simple method for estimating cyclic stress-strain curves from a static stress-strain curve was proposed. The specimens used in this study are general-purpose shipbuilding steels, and the results should be applicable to similar steels for welding and structures. © 2023 Japan Welding Society. All rights reserved.

关键词： Yield stress

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Effect of micro-friction stir welding parameters on the mechanical properties and microstructure of 5052 aluminum thin sheets

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International Journal of Advanced Manufacturing Technology 2024年第1-2期130卷 553-563页

作者： Hwang, Yeong-Maw Lu, Cheng-Yu Chen, Ren-Yu Department of Mechanical and Electro-mechanical Engineering National Sun Yat-sen University Kaohsiung804 Taiwan Department of Naval Architecture and Ocean Engineering National Kaohsiung University of Science and Technology Kaohsiung City81157 Taiwan Department of Systems & Naval Mechatronic Engineering National Cheng-Kung University Tainan City70101 Taiwan

This study utilized high rotational speeds (5500, 8500, and 10,000 rpm) and various traverse speeds (300, 600, and 900 mm/min) to carry out micro-friction stir welding on 0.8 mm thick plates of 5052–0 and 5052-H32 aluminum alloys. The weld heterogeneity was assessed through microstructural analysis and tensile testing under various process parameters. It was found that high rotational speeds generate enough heat to provide grain growth within the stirring zone. Moreover, the stirring zone showed a sizeable population of equiaxed grains, measuring less than 5 μm, that resulted in an improved mechanical strength of the joint. The joint efficiencies in the 5052-O and 5052-H32 alloys were significantly improved. The joint efficiencies of yield strength for 5052-O and 5052-H32 ranged between 129 and 139%, and 118% and 124%, respectively. The joint efficiencies of tensile strength for 5052-O varied between 102 to 109%, while in 5052-H32 they ranged from 93 to 100%. A comparison of the micro friction stir welding parameter to conventional thick plate friction stir welding showed that the former provided superior properties. © 2023, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.

关键词： Friction stir welding

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A review on cell damage,viability,and functionality during 3D bioprinting

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Military Medical Research 2023年第5期10卷 620-635页

作者： He-Qi Xu Jia-Chen Liu Zheng-Yi Zhang Chang-Xue Xu Department of Industrial Manufacturingand Systems EngineeringTexas Tech UniversityLubbockTX79409USA School of Naval Architecture and Ocean Engineering Huazhong University of Science and TechnologyWuhan430074China

Three-dimensional(3D)bioprinting fabricates 3D functional tissues/organs by accurately depositing the bioink composed of the biological materials and living *** though 3D bioprinting techniques have experienced significant advancement over the past decades,it remains challenging for 3D bioprinting to artificially fabricate functional tissues/organs with high post-printing cell viability and functionality since cells endure various types of stress during the bioprinting ***,cell viability which is affected by several factors including the stress and the environmental factors,such as pH and temperature,is mainly determined by the magnitude and duration of the stress imposed on the cells with poorer cell viability under a higher stress and a longer duration *** maintenance of high cell viability especially for those vulnerable cells,such as stem cells which are more sensitive to multiple stresses,is a key initial step to ensure the functionality of the artificial tissues/*** addition,maintaining the pluripotency of the cells such as proliferation and differentiation abilities is also essential for the 3D-bioprinted tissues/organs to be similar to native tissues/*** review discusses various pathways triggering cell damage and the major factors affecting cell viability during different bioprinting processes,summarizes the studies on cell viabilities and functionalities in different bioprinting processes,and presents several potential approaches to protect cells from injuries to ensure high cell viability and functionality.

关键词： Three-dimensional bioprinting Cell damage Shear stress Cell viability Cell functionality

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Inspection of Steel Sheet-Pile Quaywall Using Underwater Remotely Operated

Inspection of Steel Sheet-Pile Quaywall Using Underwater Rem...

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2025 IEEE Underwater Technology, UT 2025

作者： Huang, Ho-Yueh Huang, Sheng-Wei Guo, Jenhwa National Taiwan University Department of Engineering Science and Ocean Engineering Taipei Taiwan National Taiwan Ocean University Department of Systems Engineering & Naval Architecture Keelung Taiwan

ISBN: (纸本)9798331534189

Steel sheet pile wharves are integral to port infrastructure, necessitating routine inspections to ensure their structural safety and longevity. Traditional inspection methods, involving divers equipped with cameras, focus on visual assessments, thickness measurements, and cathodic protection system evaluations. While effective, these methods are labor-intensive and expose divers to significant risks. This work explores the use of a Remotely Operated Vehicle (ROV) as an alternative for inspecting two steel sheet pile wharves, labeled A and B. The ROV-based inspections were compared to conventional diver-based methods in terms of defect detection, biofouling removal efficiency, and steel thickness measurements. The findings reveal that ROV inspections offer several advantages, including enhanced safety, reduced operational time, and comparable accuracy in detecting structural anomalies. However, challenges such as limited visibility due to marine growth and calibration issues with thickness measurements were noted. This work proposes strategies to address these challenges, emphasizing the need for optimized ROV designs and improved operational protocols. By demonstrating the feasibility and benefits of ROV technology, this research provides valuable insights for advancing underwater inspection methods, ensuring safer and more efficient maintenance of steel sheet pile wharves. © 2025 IEEE.

关键词： Inspection

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Influence of Microstructural Changes on Intergranular Corrosion and Stress Corrosion Cracking of 5083-H116 Alloys

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Transactions of the Indian Institute of Metals 2024年第3期77卷 667-676页

作者： Hwang, Yeong-Maw Lu, Cheng-Yu Chen, Ren-Yu Department of Mechanical and Electro-Mechanical Engineering National Sun Yat-sen University Lien-Hai Rd. Kaohsiung804 Taiwan Department of Naval Architecture and Ocean Engineering Nation Kaohsiung University of Science and Technology Kaohsiung City81157 Taiwan Department of Systems & Naval Mechatronic Engineering National Cheng-Kung University Tainan City70101 Taiwan

The purpose of this study is to investigate the changes in the microstructure of 5083-H116 alloys under different annealing temperatures and sensitization treatments. The properties of both annealed and sensitized samples were analyzed using various techniques, including tensile testing, scanning electron microscopy, and optical microscopy. The susceptibility of the alloy to intergranular corrosion (IGC) and stress corrosion cracking (SCC) was evaluated using the nitric acid mass loss test (ASTM G67 NAMLT) and the slow strain rate test, respectively. The results indicate that annealing temperatures below 200 °C and above 300 °C resulted in high susceptibility to IGC and SCC due to the continuous precipitation of β-phase (Mg2Al3) along the grain boundaries. In contrast, annealing in the temperature range of 200–250 °C led to the formation of discontinuous β-phase precipitates at the grain boundaries, resulting in high resistance to IGC and SCC. © The Indian Institute of Metals - IIM 2023.

关键词： Stress corrosion cracking

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