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  • Author: Min Han x
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Open access

Min Zhang, Shidong Fan, Hanhua Zhua and Sen Han

Abstract

The study of the flow characteristics of the solid-fluid two phase flow in the cutter suction dredger is very important for exploring the slurry formation mechanism and optimizing the operational parameters. In this study, standard k-ε model and Multiple Reference Frame are applied to numerically simulate flow field in and around the cutting system, then with the steady convergent result of the simulation as the initial condition, Discrete Phase Mode is used to solve the particle motion equation by fully coupling the continuous phase and the particles. The influence of suction flow velocity and cutter’s rotating speed on particles suction are analyzed, and effectively suctioned particles numbers are also quantitatively studied. The simulation result shows that the DPM model is able to simulate the movement of particles in and around the cutter suction dredger’s cutting system, in the fluid flow filed velocity vector and pressure distribution on different planes show different characteristics, and under higher suction velocity and lower cutter rotating speed more particles are suctioned into the suction inlet. The results can help better understand flow characteristics of solid-fluid 2-phase-flow of cutter suction dredger’s cutting system, and provide theoretical support for relative system design and operational parameters optimization.

Open access

Chulwoong Han, Young-Min Kim, Seong Ho Son, Hanshin Choi, Tae Bum Kim and Yong Hwan Kim

Abstract

This study investigated the recovery of anodic slimes by carbothermic reaction in the temperature range of 973~1,273K and amount of carbon as a function of time. Tin anodic slime samples were collected from the bottom of the electrolytic cells during the electro-refining of tin. The anodic slimes are consisted of high concentrated tin, silver, copper and lead oxides. The kinetics of reduction were determined by means of the weight-loss measurement technique. In order to understand in detail of carbothermic reaction, thermodynamic calculation was carried out and compared with experiments. From thermodynamic calculation and experiment, it was confirmed that Sn-based anodic slime could be reduced by controlling temperature and amount of carbon. However, any tendency between the reduction temperature and carbon content for the reduction reaction was not observed.

Open access

Yonghwan Kim, Kyong-Hwan Kim, Jae-Han Kim, Taeyoung Kim, Min-Guk Seo and Yooil Kim

ABSTRACT

The present paper introduced a computer program, called WISH, which is based on a time-domain Rankine panel method. The WISH has been developed for practical use to predict the linear and nonlinear ship motion and structural loads in waves. The WISH adopts three different levels of seakeeping analysis: linear, weakly-nonlinear and weak-scatterer approaches. Later, WISH-FLEX has been developed to consider hydroelasticity effects on hull-girder structure. This program can solve the springing and whipping problems by coupling between the hydrodynamic and structural problems. More recently this development has been continued to more diverse problems, including the motion responses of multiple adjacent bodies, the effects of seakeeping in ship maneuvering, and the floating-body motion in finite-depth domain with varying bathymetry. This paper introduces a brief theoretical and numerical background of the WISH package, and some validation results. Also several applications to real ships and offshore structures are shown

Open access

Min Han, Qin Yu, Xuerong Liu, Fuqiang Hu and Hong Yuan

Abstract

The purpose of this work was to investigate a novel aqueous dispersion (Eudragit® L100-55) f or e nteric c oating o f drugs. Three different casting solutions, Eudragit® L100-55 aqueous dispersion, Eudragit® L 100-55 o rganic s olution, and Eudragit® L30D-55 aqueous dispersion, were used to prepare free films by the casting method. Drug-loaded pellets, prepared by the extrusion-spheronization method, were coated with one of these three coating solutions using the fluidized-bed spray coating technology. Properties of the free films were thoroughly investigated. Films formed by Eudragit® L100-55 aqueous dispersions showed similar properties to those formed by Eudragit® L100-55 organic solution regarding thermodynamic properties, moisture permeability, solubility and acid tolerance ability. Furthermore, the performance of the novel film was better than that formed by Eudragit® L30D-55 aqueous dispersion. Among the three enteric coating solutions, Eudragit® L100- 55 aqueous dispersion will be a promising aqueous dispersion for enteric coating and can be used in the development of enteric-coated preparations.

Open access

Wanil Byun, Min Ki Kim, Kook Jin Park, Seung Jo Kim, Minho Chung, Jin Yeon Cho and Sung-Han Park

ABSTRACT

The supercavitating vehicle is an underwater vehicle that is surrounded almost completely by a supercavity to reduce hydrodynamic drag substantially. Since the cruise speed of the vehicle is much higher than that of conventional submarines, the drag force is huge and a buckling may occur. The buckling phenomenon is analyzed in this study through static and dynamic approaches. Critical buckling load and pressure as well as buckling mode shapes are calculated using static buckling analysis and a stability map is obtained from dynamic buckling analysis. When the finite element method (FEM) is used for the buckling analysis, the solver requires a linear static solver and an eigenvalue solver. In this study, these two solvers are integrated and a consolidated buckling analysis module is constructed. Furthermore, Particle Swarm Optimization (PSO) algorithm is combined in the buckling analysis module to perform a design optimization computation of a simplified supercavitating vehicle. The simplified configuration includes cylindrical shell structure with three stiffeners. The target for the design optimization process is to minimize total weight while maintaining the given structure buckling-free.

Open access

Qi Huang, Xue-Feng Sun, Hong-Li Lin, Zhi-Min Zhang, Li-Rong Hao, Li Yao, Ji-Jun Li, De-Long Zhao, Yong Wang, Han-Yu Zhu and Xiang-Mei Chen

Abstract

Objective: The objective was to increase the understanding of vascular access in hemodialysis and evaluate hemodialysis-related anticoagulation treatments and the associated hemorrhagic or thrombotic complications. Materials and Methods: In this study, an epidemiological investigation was conducted in 1175 patients who underwent hemodialysis in seven blood purification centers in northern Chinese. The patients were divided into two groups based on the vascular access they used: Arteriovenous fistula (AVF) group and central venous catheter (CVC) group. The similarities and differences of anticoagulation and hemorrhagic, thrombotic complications were compared between two groups. Results: Arteriovenous fistula was the most frequently used vascular access, and heparin was the most commonly used anticoagulant. Patients in CVC group experienced significantly greater rates of low molecular weight heparin (LMWH) administration and had a higher rate in achieving thrombotic complications than those in AVF group. There were no significant differences in LMWH dosages in patients with thrombotic complications, as well as the proportion of patients who received anti-platelet drugs. Heparinized catheter lock solutions were excessively high in this study, which may lead to a risk of hemorrhage. Conclusion: Hemodialysis-related anticoagulation treatments in China require additional improvements, especially for the patients using CVC as vascular access. There is an urgent need to develop clinical evaluation studies of anticoagulation treatments for achieving more standardized and targeted treatments.