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Modelling the flow conditions in the tunnel and its reduced model
Mária Čarnogurská,Miroslav Příhoda,Daniela Popčáková 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.12
The article discusses the problems of flow condition modelling on real object as well as its reduced model while using similarity theory. Similarity criteria and model flow laws are derived by means of dimensional analysis. Presented is the computation of flow through the tunnel and its reduced model as well as the applied numerical methods.
FREE PRODUCTS OF OPERATOR SYSTEMS
Pop, Florin Korean Mathematical Society 2022 대한수학회보 Vol.59 No.3
In this paper we introduce the notion of universal free product for operator systems and operator spaces, and prove extension results for the operator system lifting property (OSLP) and operator system local lifting property (OSLLP) to the universal free product.
Pop-Paul Ewphun,Chau Tan Vo,Prathan Srichai,Chinda Charoenphonphanich,Susumu Sato,Hidenori Kosaka 한국자동차공학회 2017 International journal of automotive technology Vol.18 No.4
This paper investigates the effects of Hydrotreated vegetable oil-diesel blend to combustion characteristics under various ambient oxygen concentrations and ambient pressure. Combustion characteristics were investigated using heat release rate analysis, two color method, soot concentration measurement and NOx concentration measurement. The experiments were carried out on a rapid compression expansion machine to simulate the ambient condition of a CI engine at TDC. Synthetic gas with oxygen concentrations of 21 %, 15 % and 10 % were used to simulate EGR conditions. A single hole injector was used with five different fuels: commercial diesel, HVO-commercial diesel blends and HVO. The results showed that increasing HVO blending percentages decreased ignition delay, flame temperature, soot concentration and NOx concentration. Heat release at oxygen concentration of 10 % dramatically dropped due to a shortened ignition delay, which resulted in less combustion. A decreased oxygen concentration from applied EGR conditions not only increased ignition delay, heat release, flame temperature and NOx concentration, but also increased soot concentration. A combination of EGR and supercharged conditions by increasing ambient pressure and decreasing oxygen concentrations resulted in increased heat release, decreased flame temperature, ignition delay and soot concentration, compared to EGR conditions.
AN ALGORITHM FOR SOLVING THE PROBLEM OF CONVEX PROGRAMMING WITH SEVERAL OBJECTIVE FUNCTIONS
Cocan, Moise,Pop, Bogdana 한국전산응용수학회 1999 Journal of applied mathematics & informatics Vol.6 No.1
This work aims to establish an algorithm for solving the problem of convex programming with several objective-functions with linear constraints. Starting from the idea of Rosen's algorithm for solving the problem of convex programming with linear con-straints and taking into account the solution concept from multi-dimensional programming represented by a program which reaches "the best compromise" we are extending this method in the case of multidimensional programming. The concept of direction of min-imization is introduced and a necessary and sufficient condition is given for a s∈Rn direction to be a direction is min-imal. The two numerical examples presented at the end validate the algorithm.
INJECTION CHARACTERISTICS OF PALM METHYL ESTER BLENDED WITH DIESEL USING ZUECH’S CHAMBER
Prathan Srichai,Pop-Paul Ewphun,Chinda Charoenphonphanich,Preechar Karin,Manida Tongroon,Nuwong Chollacoop 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.3
This research attempts to characterize the injection of palm biodiesel blended with diesel in a Zuech’s chamber. Thailand conventional diesel (mandated blend of biodiesel at 5 % or B5), palm biodiesel (B100) and four other biodiesel blends ratios (B20, B40, B60 and B80) were investigated with single hole injector of 140 and 200 μm diameters, injection pressure of 40 MPa to 160 MPa, constant back pressure of 4.5 MPa and energize time of 2.5 ms. The results show that increasing biodiesel blending ratios leads to longer injection delay, larger injection pressure drop, smaller injection quantity discharge coefficient (Cd) and shorter injection duration. With increasing biodiesel blending ratio, high Cavitation number from biodiesel viscosity decreases Reynolds number. Increasing injector diameter from 140 μm to 200 μm has reduced injection delay, increased fuel injection quantity, discharge coefficient and remaining injection duration. The increasing of injection pressure were improve, injection delay, injection duration, injection quantity and discharge coefficient until injection pressure 120 MPa. In addition at injection pressure over 120 MPa are decrease injection quantity and discharge coefficient, it effect form the cavitation phenomena. Increasing of viscosity, density, Bulk modulus and sound velocity were effect to increase injection delay, with reduce injection quantity, injection duration and pressure drop during injection process.