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Wyszukujesz frazę "Ha, Nguyen Thi Hai" wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Numerical prediction of propeller-hull interaction characteristics using RANS method
Autorzy:
Tu, Tran Ngoc
Luu, Do Duc
Ha, Nguyen Thi Hai
Quynh, Nguyen Thi Thu
Vu, Nguyen Minh
Powiązania:
https://bibliotekanauki.pl/articles/258472.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
propeller
interaction
hull
wake fraction
thrust deduction
relative rotative efficiency
RANS equations
Opis:
The paper presents the results of computational evaluation of the hull-propeller interaction coefficients, also referred to propulsive coefficients, based on the unsteady RANS flow model. To obtain the propulsive coefficients, the ship resistance, the open-water characteristics of the propeller, and the flow past the hull with working propeller were computed. For numerical evaluation of propeller open-water characteristics, the rotating reference frame approach was used, while for self-propulsion simulation, the rigid body motion method was applied. The rotating propeller was modelled with the sliding mesh technique. The dynamic sinkage and trim of the vessel were considered. The free surface effects were included by employing the volume of fluid method (VOF) for multi-phase flows. The self-propulsion point was obtained by performing two runs at constant speed with different revolutions. The well-known Japan Bulk Carrier (JBC) test cases were used to verify and validate the accuracy of the case studies. The solver used in the study was the commercial package Star-CCM+ from SIEMENS.
Źródło:
Polish Maritime Research; 2019, 2; 163-172
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance Investigation of High-Speed Train OFDM Systems under the Geometry-Based Channel Model
Autorzy:
Do, Viet Ha
Trinh, Thi Huong
Nguyen, Thanh Hai
Powiązania:
https://bibliotekanauki.pl/articles/1844506.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high-speed train systems
geometry-based channel models
OFDM systems
SINR
capacity
Opis:
The high-speed of train (HST) in combination with the high carrier frequency of HST systems leads to the severe inter carrier interference (ICI) in the HST orthogonal frequency division multiplexing (HST-OFDM) systems. To avoid the complexity in OFDM receiver design for ICI eliminations, the OFDM system parameters such as symbol duration, signal bandwidth, and the number of subcarriers should be chosen appropriately. This paper aims to propose a process of HST-OFDM system performance investigation to determine these parameters in order to enhance spectral efficiency and meet a given quality-of-service (QoS) level. The signal-to-interference-plus-noise ratio (SINR) has been used as a figure of merit to analyze the system performance instead of signal-to-noise ratio (SNR) as most of recent research studies. Firstly, using the non-stationary geometry-based stochastic HST channel model, the SINR of each subcarrier has been derived for different speeds of the train, signal bandwidths, and number of subcarriers. Consequently, the system capacity has been formulated as the sum of all the single channel capacity from each sub-carrier. The constraints on designing HST-OFDM system parameters have been thoughtfully analyzed using the obtained expressions of SINR and capacity. Finally, by analyzing the numerical results, the system parameters can be found for the design of HST-OFDM systems under different speeds of train. The proposed process can be used to provide hints to predict performance of HST communication systems before doing further high cost implementations as hardware designs.
Źródło:
International Journal of Electronics and Telecommunications; 2021, 67, 3; 451-457
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new environmentally friendly chemical mechanical polishing method applied for surface finishing Ti-6Al-4V alloy
Autorzy:
Quang, Nguyen Minh
Quan, Nguyen Ngoc
Mai, Nguyen Trong
Thanh, Le Thi Phuong
Tung, Nguyen Tien
Tan, Tran Ngoc
Hai, Ha Thanh
Trinh, Nguyen Duy
Powiązania:
https://bibliotekanauki.pl/articles/28407325.pdf
Data publikacji:
2023
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
chemical-mechanical polishing
hydrogen peroxide
TI-6AL-4V
silica
malic acid
Opis:
A new eco-friendly slurry has been developed for the chemical mechanical polishing process with a solution of malic acid, deionized water, and an oxidizing agent hydrogen peroxide (H2O2). The surface quality of Ti-6Al-4V workpieces with the proposed chemical mechanical polishing slurry with optimal parameters include oxidizers (H2O2), colloidal (SiO2) slurry, and deionized water by weight 8%, 45%, and 47% respectively, the pH concentration is adjusted 4 through the malic acid content present in the slurry. Experimental results obtained with the proposed chemical mechanical polishing method show a more improved surface quality than previous studies when applying for polishing Ti-6Al-4V alloy. The developed chemical mechanical polishing method's polishing results under optimal conditions obtain an ultra-fine surface quality with Ra = 0.696 nm over a measuring area of 53×70 μm2. X-ray photoelectron (XPS) and electrochemical measurements were used to study the chemical reaction mechanisms in the proposed chemical mechanical polishing process. The chemical mechanical polishing processes for the surface of the Ti-6Al-4V alloy workpiece with the H2O2 oxidizing agent showed high suitability with the reactants formed on the surface such as Ti, V, and Al oxide. With the proposed oxidant and the established chemical mechanical polishing slurry, the feasibility and surface quality of the super smooth Ti-6Al-4V workpiece formed after polishing were demonstrated. The established chemical mechanical polishing method shows high applicability in environmental protection and Ti-6Al-4V alloy ultra-precision machining industries.
Źródło:
Journal of Machine Engineering; 2023, 23, 4; 64--76
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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