Calm Water is a Mirror: Neo-Confucian Meditation in the Chosŏn Dynasty

2021 ◽  
Vol 12 (1) ◽  
pp. 73-96
Author(s):  
Guy S. Shababo
Keyword(s):  
Choson Dynasty ◽  
Calm Water

Numerical evaluation of hydrodynamic characteristics of planing hulls by using a hybrid method

2021 ◽  
pp. 147509022199024
Author(s):  
Emre Kahramanoglu ◽  
Silvia Pennino ◽  
Huseyin Yilmaz
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Design Stage ◽  
Hydrodynamic Characteristics ◽  
Calm Water ◽  
Preliminary Design Stage ◽  
Reduction Function ◽  
Hull Forms ◽  
Good Agreement

The hydrodynamic characteristics of the planing hulls in particular at the planing regime are completely different from the conventional hull forms and the determination of these characteristics is more complicated. In the present study, calm water hydrodynamic characteristics of planing hulls are investigated using a hybrid method. The hybrid method combines the dynamic trim and sinkage from the Zarnick approach with the Savitsky method in order to calculate the total resistance of the planing hull. Since the obtained dynamic trim and sinkage values by using the original Zarnick approach are not in good agreement with experimental data, an improvement is applied to the hybrid method using a reduction function proposed by Garme. The numerical results obtained by the hybrid and improved hybrid method are compared with each other and available experimental data. The results indicate that the improved hybrid method gives better results compared to the hybrid method, especially for the dynamic trim and resistance. Although the results have some discrepancies with experimental data in terms of resistance, trim and sinkage, the improved hybrid method becomes appealing particularly for the preliminary design stage of the planing hulls.

scholarly journals An Approach to Determine Optimal Bow Configuration of Polar Ships under Combined Ice and Calm-Water Conditions

2021 ◽  
Vol 9 (6) ◽  
pp. 680
Author(s):  
Hui Li ◽  
Yan Feng ◽  
Muk Chen Ong ◽  
Xin Zhao ◽  
Li Zhou
Keyword(s):  
Numerical Simulation ◽  
Water Resistance ◽  
Numerical Technique ◽  
Experimental Studies ◽  
Resistance Index ◽  
Simulation Method ◽  
Present Approach ◽  
Calm Water ◽  
Level Ice ◽  
Ice Resistance

Selecting an optimal bow configuration is critical to the preliminary design of polar ships. This paper proposes an approach to determine the optimal bow of polar ships based on present numerical simulation and available published experimental studies. Unlike conventional methods, the present approach integrates both ice resistance and calm-water resistance with the navigating time. A numerical simulation method of an icebreaking vessel going straight ahead in level ice is developed using SPH (smoothed particle hydrodynamics) numerical technique of LS-DYNA. The present numerical results for the ice resistance in level ice are in satisfactory agreement with the available published experimental data. The bow configurations with superior icebreaking capability are obtained by analyzing the sensitivities due to the buttock angle γ, the frame angle β and the waterline angle α. The calm-water resistance is calculated using FVM (finite volume method). Finally, an overall resistance index devised from the ship resistance in ice/water weighted by their corresponding weighted navigation time is proposed. The present approach can be used for evaluating the integrated resistance performance of the polar ships operating in both a water route and ice route.

scholarly journals Coupled Engine-Propeller Selection Procedure to Minimize Fuel Consumption at a Specified Speed

2021 ◽  
Vol 9 (1) ◽  
pp. 59
Author(s):  
Mina Tadros ◽  
Roberto Vettor ◽  
Manuel Ventura ◽  
Carlos Guedes Soares
Keyword(s):  
Fuel Consumption ◽  
Selection Procedure ◽  
Optimization Procedure ◽  
Operating Point ◽  
Power Prediction ◽  
Ship Routing ◽  
Marine Propellers ◽  
Operational Profile ◽  
Calm Water ◽  
Engine Operating Point

This study presents a practical optimization procedure that couples the NavCad power prediction tool and a nonlinear optimizer integrated into the Matlab environment. This developed model aims at selecting a propeller at the engine operating point with minimum fuel consumption for different ship speeds in calm water condition. The procedure takes into account both the efficiency of the propeller and the specific fuel consumption of the engine. It is focused on reducing fuel consumption for the expected operational profile of the ship, contributing to energy efficiency in a complementary way as ship routing does. This model assists the ship and propeller designers in selecting the main parameters of the geometry, the operating point of a fixed-pitch propeller from Wageningen B-series and to define the gearbox ratio by minimizing the fuel consumption of a container ship, rather than only maximizing the propeller efficiency. Optimized results of the performance of several marine propellers with different number of blades working at different cruising speeds are also presented for comparison, while verifying the strength, cavitation and noise issues for each simulated case.

Managing the Health of Chosŏn Kings: Illness and Treatment in the Daily Records of the Royal Secretariat

2016 ◽  
Vol 11 (1-2) ◽  
pp. 171-191 ◽  
Author(s):  
Wung Seok Cha
Keyword(s):  
Social History ◽  
Mental Status ◽  
Daily Activities ◽  
The Political ◽  
Korean Language ◽  
Historical Source ◽  
Choson Dynasty ◽  
The Social ◽  
History Of ◽  
Shed Light

TheSŭngjŏngwŏn ilgi (Daily Records of the Royal Secretariat)is one of the major chronicles of the events of the Chosŏn Dynasty (1392–1910). Although the records prior to the year 1622 are no longer extant, the remaining records from the years 1623 to 1910 meticulously recount the daily activities of the reigning Chosŏn kings, including copious information on their physical and mental status. Because the king’s health was considered as important as other official affairs in many respects, detailed records were kept of royal ailments and how court doctors treated them. This article surveys the state of Korean-language scholarship on the medical content of theDaily Recordsand presents selected translations to demonstrate how this valuable historical source can shed light on both the social history of Chosŏn medicine and the political importance of kingly health at the Chosŏn court.

Optimization of RANS Solver Simulation Setup for Propeller Open Water Performance Prediction

2015 ◽  
Author(s):  
Mohammed Islam ◽  
Fatima Jahra ◽  
Michael Doucet
Keyword(s):  
Domain Size ◽  
Open Water ◽  
Fractional Factorial ◽  
Navier Stokes ◽  
Calm Water ◽  
Simulation Results ◽  
Open Water Performance ◽  
Thrust And Torque ◽  
Simulation Time ◽  
Fixed Pitch

Mesh and domain optimization strategies for a RANS solver to accurately estimate the open water propulsive characteristics of fixed pitch propellers are proposed based on examining the effect of different mesh and computation domain parameters. The optimized mesh and domain size parameters were selected using Design of Experiments (DoE) methods enabling simulations to be carried out in a limited memory environment, and in a timely manner; without compromising the accuracy of results. A Reynolds-Averaged Navier Stokes solver is used to predict the propulsive performance of a fixed pitch propeller. The predicted thrust and torque for the propeller were compared to the corresponding measurements. A total of six meshing parameters were selected that could affect the computational results of propeller open water performance. A two-level fractional factorial design was used to screen out parameters that do not significantly contribute to explaining the dependent parameters: namely simulation time, propeller thrust and propeller torque. A total of 32 simulations were carried out only to find out that the selected six meshing parameters were significant in defining the response parameters. Optimum values of each of the input parameters were obtained for the DOE technique and additional simulations were run with those parameters. The simulation results were validated using open water experimental results of the same propeller. It was found that with the optimized meshing arrangement, the propeller opens simulation time was reduced by at least a factor of 6 as compared to the generally popular meshing arrangement. Also, the accuracy of propulsive characteristics was improved by up to 50% as compared to published simulation results. The methodologies presented in this paper can be similarly applied to other simulations such as calm water ship resistance, ship propulsion to systematically derive the optimized meshing arrangement for simulations with minimal simulation time and maximum accuracy. This investigation was carried out using STAR-CCM+, a commercial CFD package; however the findings can be applied to any RANS solver.

Assessment of experiments and CFD for the semi-planing R/V Athena Model in calm water

2021 ◽  
Vol 236 ◽  
pp. 109254
Author(s):  
Evan J. Lee ◽  
Maysam Mousaviraad ◽  
Charles R. Weil ◽  
Minyee J. Jiang ◽  
Anne M. Fullerton ◽  
...  
Keyword(s):  
Calm Water

Structural Integrity Assessment of Free-Fall Lifeboats by Combining Fast Monte-Carlo Simulations With CFD by Means of Proxy Load Variables

2016 ◽  
Author(s):  
Sébastien Fouques ◽  
Ole Andreas Hermundstad
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Structural Integrity ◽  
Free Fall ◽  
Integrity Assessment ◽  
Proxy Variables ◽  
Pressure Load ◽  
Calm Water ◽  
Measured Pressure

The paper is concerned with the launch of free-fall lifeboats (FFL). It proposes a method that complies with the DNV-OS-E406 standard in order to select characteristic launches from Monte Carlo simulations for further structural load assessment with CFD and FEM. Proxy variables derived from kinematic parameters and aiming at predicting pressure load indicators are computed with the VARUNA launch simulator developed by MARINTEK. The statistical distributions of the proxy variables obtained from the Monte Carlo simulations are used to identify critical scenarios, and characteristic launches can then be selected from a chosen probability level. The feasibility of the proposed method is documented in the paper for several types of pressure loads. Existing model test data from various FFL-launch campaigns in calm water and in waves are used to compute the proxy variables as it would be done in the VARUNA simulator. Scatter diagrams showing the correlation with actual measured pressure load indicators are then established to assess the quality of the chosen proxy variables.

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