1,721,073 research outputs found
Study on numerical PMM test and its application to KCS hull
No full text© 2022The planar motion mechanism (PMM) test is among the most popular methods to evaluate ship manoeuvrability due to its ability to generate manoeuvring coefficients through a series of captive tests. As a replacement for conventional towing tank facilities, the present work applies an open-source-based computational fluid dynamics (CFD) solver to conduct numerical tests, including the static drift, pure sway, pure yaw, and combined drift-yaw tests. The test model is the KRISO container ship (KCS), which has a highly-curved hull with sharp edges and extruded bulbous bow. The original k-ω SST turbulence model has been enhanced to stabilize the turbulence fields near the free surface as well as the hull, and the bow and stern vortices that occur during the ship's PMM motions are displayed in the present CFD analysis. For both the static and dynamic tests, the force and moment predicted by the present CFD solver agree well with the experimental measurements. The numerical PMM tests have generated a complete list of manoeuvring coefficients for the bare hull, and the further application to ship 35° turning circle test has demonstrated a reasonable agreement with the direct free-running experiments.N
Outlier analysis of sloshing impact loads on liquid ship cargo
No full text© IMechE 2022.This paper introduces an outlier analysis which can improve the convergence of the statistical analysis results of sloshing model test data. The paper classify possible outliers in the sloshing model test into three categories and present a treatment method for each outlier. The developed outlier analysis is adapted to the model test results for the cargo of the liquefied-natural-gas (LNG) carrier in operation. The results of the present new method are compared with those of the conventional procedure, particularly focusing on long-term sloshing prediction. Through this study, the effectiveness of the present method is observed, and it is found that the present method provides is robust and reliable results in the application of experimental data for load prediction.N
Comparison of sloshing-induced pressure in different scale tanks
No full textThis paper considers scale effects on three-dimensional (3D) sloshing flows. A series of model tests were conducted for three differently scaled tanks. The model tanks considered in this study were 1:70, 1:50, and 1:30 scaled membrane type tanks based on a 138,000 m(3) liquid natural gas carrier model. The tests were carried out for harmonic sway and roll motions for three different filling depths and with various excitation frequencies. The pressure measuring points in the tanks were the same, as if they were scaled up to actual size. The main parameters investigated in this study were the pressure peak and rise time of sampled sloshing pressures. These key sloshing load parameters were systematically analysed by a statistical approach, and the results from the tests at different scales were compared.OAIID:RECH_ACHV_DSTSH_NO:T201703108RECH_ACHV_FG:RR00200001ADJUST_YN:EMP_ID:A076309CITE_RATE:1.387DEPT_NM:조선해양공학과EMAIL:[email protected]_YN:YN
Real-time digital twin for ship operation in waves
No full textThis paper introduces a real-time digital twin for ship operations in seaways. The concept of the digital twin is becoming popular, and it is adopted for ship operation systems in this study. In particular, this paper introduces a new and innovative concept of the digital twin to predict ocean waves and hydrodynamic performances, such as seakeeping and maneuvering, which enables the risk and optimum route to be forecast in real time. An essential element in the realization of such a real-time digital twin is the real-time prediction of ocean waves. Hence, a sophisticated algorithm for wave reconstruction using measured wave-radar images is developed, which is extended to predicting the future evolution of a three-dimensional wave field in front of a ship within a time window of the order of 10 min. As another essential element, an analysis program to solve the coupled seakeeping-maneuvering problem is developed. This analysis can also be used in real time. By combining this with wave prediction software, the future occurrence of ocean waves and ship responses can be predicted. By extending this approach, the risk and performance of ships in various ocean environments can be predicted. In this paper, concepts, approaches, and examples are introduced.Y
Immobilization of KTS-3 on an electrospun fiber membrane for efficient removal of Cs+ and Sr2+
No full textThe need to treat radioactive aqueous waste has increased, and decontamination of such waste is of high priority. This study demonstrates a method of fabricating a new composite membrane to effectively remove Cs+ and Sr2+ ions using KTS-3, a metal sulfide ion exchanger. The study utilized an electrospinning method to fabricate polyacrylonitrile (PAN) nanofiber support to immobilize the adsorbent KTS-3. Through pulverization using ball milling, KTS-3 was dispersed evenly and fixed to the PAN support which offered high water-permeability and large surface area. The ratio of KTS-3 to the polymer support was optimized to maximize the adsorption performance of the composite membrane. Consequently, we obtained high maximum adsorption capacities of 133.6 and 32.4 mg g− 1 for Cs+ and Sr2+, respectively. Moreover, the high adsorption capacity was kept in the filtration test when the flux reaches 2000 L m− 2 h− 1. The newly fabricated material provides an attractive strategy to utilize adsorbents effectively for the continuous selective removal of radionuclides from contaminated wastewater
Effective Immobilization of Potassium Copper Hexacyanoferrate Via Amino-Functionalization of Magnetic Chitosan Adsorbent for Selective Cs+ Separation
No full textPotassium Copper Hexacyanoferrate-Embedded Doubly-Crosslinked Magnetic Hydrogel for Effective Cs+ Removal and Facile Recovery
No full textMagneto-optic property measurement of bismuth substituted yttrium iron garnet films prepared by metal-organic-decomposition method at the 1310-nm and 1550-nm wavelengths
No full textWe have measured the magneto-optic (MO) properties of film-type bismuth substituted yttrium iron garnets (Bi1.5:YIG, Bi1.5Y1.5Fe5O12) prepared by using metal-organic-decomposition (MOD) method on glass substrates at the 1310-nm and 1550-nm wavelengths. The Verdet constant of the Bi1.5:YIG film in the unsaturated linear magnetization region has been experimentally determined from a sensitive measurement of the Faraday rotation of the Bi1.5:YIG films with a lock-in amplifier and an auto-balanced photoreceiver under alternating magnetic fields. The Bi:YIG films have been deposited on silica glass substrates without any buffer layer and with one of buffer layers of Bi1Y2Fe5O12 (Bi1:YIG) and Bi1Fe4Ga1Nd2O12 (Bi1:NIGG) which are used to compensate mismatch of the lattice constant and thermal expansion coefficient between the film and substrate. The maximum value of the measured Faraday rotation of the Bi1.5:YIG film was over 94.6 and 156.5 °/cm for an applied unsaturated magnetic field of 100 Gauss at wavelengths of 1310 and 1550 nm, respectively, when it was prepared at annealing temperature of 700 °C and annealing speed of 1 °C/min. The absorption coefficients of the Bi1.5:YIG films were measured to be 70 cm−1 and 330 cm−1, respectively, at each of the wavelengths, and the average Gilbert damping coefficient of the Bi1.5:YIG film with a Bi1:NIGG buffer layer was measured to be 6.42 ± 18.09 × 10−4 (with the minimum value of 0 and the maximum value of 24.51 × 10−4) from a conventional ferromagnetic resonance (FMR) measurement system. Our experimental result indicates that the magneto-optic property of the Bi:YIG films prepared by the MOD method is unstable and fluctuates from run to run although its average magnetic property may be useful for application to compact integrated optical isolators under an easy solution-based fabrication process. © 2019 Elsevier B.V.1
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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