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Wyszukujesz frazę "Nguyen, Vu" wg kryterium: Autor


Tytuł:
Experimental and Mesoscopic Lattice Numerical Investigation of Increase of Chloride Diffusivity Coefficient during Uniaxial Loading Model
Eksperymentalne i mezoskopowe badanie numeryczne sieci krystalicznej wzrostu współczynnika dyfuzyjności chlorków podczas jednoosiowego modelu obciążenia
Autorzy:
Bui, Truong Son
Pham, Duc Tho
Tran, The Truyen
Nguyen, Thi Nu
Vu, Minh Ngoc
Powiązania:
https://bibliotekanauki.pl/articles/317898.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
lattice model
durability of concrete
coastal regions
chloride diffusion
model kratowy
trwałość betonu w regionach nadmorskich
dyfuzja chlorków
Opis:
This paper presents experimental and simulation results of the change in the chloride diffusion coefficient of concrete C40 (f’c=40 MPa) during axial loading. Test Method for Electrical Indication was used to measure the chloride diffusivity of the concrete sample during the axial loading. A mesoscopic lattice model is proposed to describe the variation of chloride diffusion coefficient versus damage variable. In such a model, the domain of material is discretized randomly by using Voronoi tessellation for the transport element and Delaunay triangulation for a mechanical element. At the mesoscale, the concrete is constituted by three phases: aggregate, cement paste and ITZ, in which aggregate is assumed to be elastic while cement matrix and ITZ are represented by a damage model with softening. The experimental and numerical results show that in the first stage, without crack (s < 40%smax), the chloride diffusion coefficient remains almost constant, however in the crack initiation and propagation stage (s = 60-80%smax) chloride diffusion coefficient increases significantly. An empirical power model is also proposed to describe the increase of the chloride diffusion coefficient versus stress level and damage variable.
W artykule przedstawiono wyniki doświadczalne i symulacyjne zmiany współczynnika dyfuzji chlorków betonu C40 (f’c = 40 MPa) podczas obciążenia osiowego. Do pomiaru dyfuzyjności chlorków próbki betonu podczas obciążenia osiowego wykorzystano metodę badania wskazań elektrycznych. Zaproponowano mezoskopowy model sieci krystalicznej w celu opisania zmiany współczynnika dyfuzji chlorków w funkcji zmiennej uszkodzenia. W takim modelu domena materiału jest dyskretyzowana losowo przy użyciu teselacji Voronoia dla elementu transportowego i triangulacji Delaunaya dla elementu mechanicznego. W mezoskali beton składa się z trzech faz: kruszywa, zaczynu cementowego i ITZ, w których zakłada się, że kruszywo jest elastyczne, natomiast osnowa cementowa i ITZ są reprezentowane przez model uszkodzenia ze zmiękczeniem. Wyniki eksperymentalne i numeryczne pokazują, że w pierwszym etapie, bez pęknięcia ((σ<40%σmax), współczynnik dyfuzji chlorków pozostaje prawie stały, natomiast w fazie inicjacji i propagacji pęknięcia (σ=60-80% σmax) współczynnik dyfuzji chlorków znacznie wzrasta. Zaproponowano również empiryczny model mocy opisujący wzrost współczynnika dyfuzji chlorków w funkcji poziomu naprężenia i zmiennej uszkodzenia.
Źródło:
Inżynieria Mineralna; 2020, 1, 2; 23-30
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research, Calculation and Proposal of Ventilation Solution for Duong Huy Coal Mine when Mining Down to -250 m Depth
Autorzy:
Dao, Van Chi
Le, Tien Dung
Vu, Thai Tien Dung
Nguyen, Hong Cuong
Powiązania:
https://bibliotekanauki.pl/articles/2020250.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
main fan
working mode
ventilation
airflow
air pressure
air velocity
wentylacja
ciśnienie
powietrze
Opis:
At present, according to the extraction plan in the year 2020 of Duong Huy Coal Company - Vinacomin, the mining is divided into three main zones: Central Zone extracts 06 faces; South Zone extracts 2 faces and Northeast Zone extracts 2 faces. The designated total production of all zones is 1,880,000 tons/year. To ensure the production of each mining zone, exhaust fan stations are installed at ventilation roadway adits with a total of 05 main fan stations. However, in the near future, to ensure and maintain production activities, the mine is being planned and operated using 03 main fan stations. The calculation results for the reasonable working mode of fan stations are as follows: for fan station FBCDZ8-№32B at level +47 m, airflow is 167.69 m3 /s and air pressure is 243.74 mm H2O; for fan station 2K56- №30 level +40 m, airflow is 123.37 m3 /s and air pressure is 324.79 mm H2O; for fan station FBCDZ-8- №32B at level +44 m, airflow is 167.69 m3 /s and air pressure is 354.99 mm H2O.
Źródło:
Inżynieria Mineralna; 2021, 2; 513--520
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sediment discharge and storage over the last deglacial highstand period on the central Vietnam shelf off Nha Trang
Autorzy:
Dung, Bui Viet
Stattegger, Karl
Kieu, Nguyen Van
Thanh, Nguyen Trung
Thong, Bui Xuan
Vu, Pham Nguyen Ha
Man, Ha Quang
Trang, Pham Hong
Powiązania:
https://bibliotekanauki.pl/articles/2058662.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
sediment budget
Nha Trang shelf
central Vietnam
Holocene highstand
sequence stratigraphy
Opis:
A sediment budget for the central Vietnam shelf off Nha Trang over the last deglacial Holocene highstand period has been investigated on the basis of shallow seismic and sediment core data and empirical equations. The annual suspended sediment discharge to the Nha Trang shelf ranges from: 4.3 to 5.4 Mt/year. Estimates based on published empirical equations suggest that the sediment discharge by three main local mountainous rivers (the Cai, Dinh and Van Phong rivers) that enter the Nha Trang shelf ranges between 1.7 and 4 Mt/year, which implies that the local rivers discharge approximately 75% of the total annual sediment input to the shelf. The annual sediment supply of the Cai River is approximately 2 and 6 times higher than that of the Dinh and Van Phong rivers, respectively. The highstand sediment depocentre of the Nha Trang shelf is mostly attached to the local river outflows, indicating their importance as the principal sediment supply sources to the shelf. Additional sources of sediment supply to the Nha Trang shelf can probably be related to along-shore transport from the nearby shelves. Calculations based on seismic and sediment core data indicate that the net sediment volume storage on the Nha Trang shelf is approximately 2.15 Mt/year. Approximately 50% of the total sediment yield supplied to the shelf is probably transported along-shore to the south. The sediment budget model for highstand deposits on the Nha Trang shelf is typical for a small mountainous river basin, which is significantly different from that of the large river delta systems in Vietnam such as the Mekong and Red rivers where 90% of the river sediments are captured on the delta plain/subaqueous part and only 10% of the river sediments are transported to the nearby shelf. In contrast, most of the sediments supplied by small mountainous rivers off Nha Trang are transported to the mid-shelf, forming a shore-parallel mud depocentre.
Źródło:
Geological Quarterly; 2019, 63, 2; 395--406
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of the heat source and thermal material model parameters for the laser engineered net shaping
Autorzy:
Hajder, Lucyna
Zhang, Tao
Nguyen, Vu
Powiązania:
https://bibliotekanauki.pl/articles/29520077.pdf
Data publikacji:
2022
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
additive manufacturing
finite element analysis
heat source model
thermal analysis
Opis:
The research’s primary goal is to identify the heat source and thermal material model parameters for the numerical simulation of the laser engineered net shaping (LENS). Inconel 718 was selected as a case study for the current investigation. The LENS process’s numerical model was developed within commercial finite element software and was used as a direct problem model during the parameter identification stage. Experimental data were obtained based on a rectangular-shaped sample with thermocouples located under the based material surface. The recorded thermal profiles were used to establish a goal function for the parameter identification stage. As a result, parameters describing the melt pool geometry during the additive manufacturing, as well as thermal coefficients describing interactions between the sample material and surrounding/base material, were determined.
Źródło:
Computer Methods in Materials Science; 2022, 22, 1; 43-54
2720-4081
2720-3948
Pojawia się w:
Computer Methods in Materials Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigating the effect of water depth on ship resistance using RANS CFD method
Autorzy:
Hoa, Nguyen Thi Ngoc
Vu, Bich Ngoc
Tran, Ngoc Tu
Chien, Nguyen Manh
Le, Tat Hien
Powiązania:
https://bibliotekanauki.pl/articles/259677.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship resistance
shallow water
RANS
Opis:
On inland waterways the ship resistance and propulsive characteristics are strictly related to the depth of the waterway, thus it is important to have an understanding of the influence of water depth on ship hydrodynamic characteristics. Therefore, accurate predictions of hydrodynamic forces in restricted waterways are required and important. The aim of this paper is investigating the capability of the commercial unsteady Reynolds– Averaged Navier–Stokes (RANS) solver to predict the influence of water depth on ship resistance. The volume of fluid method (VOF) is applied to simulate the free surface flow around the ship. The hull resistance in shallow and deep water is compared. The obtained numerical results are validated against related experimental studies available in the literature.
Źródło:
Polish Maritime Research; 2019, 3; 56-64
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statistical evaluation of the geochemical data for prospecting polymetallic mineralization in the Suoi Thau–Sang Than region, Northeast Vietnam
Autorzy:
Hung, Khuong The
Sang, Pham Nhu
Phuong, Nguyen
Linh, Vu Thai
Sang, Bui Viet
Powiązania:
https://bibliotekanauki.pl/articles/1841771.pdf
Data publikacji:
2020
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
polymetallic mineralization
statistical evaluation
Suoi Thau-Sang Than region
Vietnam
Opis:
In Northeast Vietnam, Suoi Thau-Sang Than is considered as a high potential area of polymetallic deposits. 1,720 geochemical samples were used to investigate polymetallic mineralization; thereby polymetallic ore occurrences in this study region were discovered and the statistical and multivariate analysis helps to define geochemical anomalies in some northeastern regions, namely Suoi Thau, Sang Than, and Ban Kep. The statistical method and cluster analysis of geochemical data indicate that the Cu, Pb, and Zn elements are good indicators, and most of them comply with the lognormal or gamma distribution. Based on the third-order threshold, the geochemical anomalies of the content of the Cu, Pb, and Zn elements reflect the concentration of copper forming ore bodies in the mineralized zone, and clearly show the concentration in three distinct zones. The trend surface analysis which was employed to determine spatial variations and relationships among these good indicator elements and anomalous areas revealed relative changes in the content of the indicator elements, and they can be considered as regular. Moreover, the goodness of fit obtained trend functions of Pb and Zn, and Cu elements is a third-degree trend surface model. These results indicate that the models can be useful in studying geochemical anomalies and analyzing the tendency of the concentration of indicator elements in the Suoi Thau-Sang Than region. Additionally, it is suggested that the statistical analysis shows a remarkable potential to use the bottom river sediments in the region to investigate polymetallic mineralization. Moreover, geochemical data can help to evaluate geochemical anomalies of the pathfinder elements and potential mineral mapping of the Suoi Thau-Sang Than region in Northeast Vietnam.
Źródło:
Geology, Geophysics and Environment; 2020, 46, 4; 285-299
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Utility of GSMap Precipitation and Point Scale in Gauge Measurements for Stream Flow Modelling – A Case Study in Lam River Basin, Vietnam
Autorzy:
Kha, Dang Dinh
Nhu, Nguyen Y.
Long, Vu Viet
Van, Dao Thi Hong
Powiązania:
https://bibliotekanauki.pl/articles/123552.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
GSMaP
SWAT model
merging
Lam river basin
flow modelling
Opis:
The benefit from integrating the information from multi-source was confirmed in the research of hydrologic processes in river basins. However, the use of satellite-based rainfall products in hydrologic stream flow modeling has been limited because of the perceived uncertainty associated with such data. In this study the authors presented the simulated streamflow from a SWAT model driven by merging rainfall between satellite and gauge-observed rainfall for the Lam River Basin. The results demonstrate the usefulness of merging rainfall data for stream flow modelling at a monthly time step.
Źródło:
Journal of Ecological Engineering; 2020, 21, 2; 39-45
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Removal of Nitramine Explosives in Aqueous Solution by UV-Mediated Advanced Oxidation Process in Near-Neutral Conditions
Autorzy:
Khue, Do Ngoc
Bach, Vu Quang
Binh, Nguyen Thanh
Minh, Do Binh
Nam, Pham Thi
Loi, Vu Duc
Nguyen, Hoa Thanh
Powiązania:
https://bibliotekanauki.pl/articles/1838360.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
hexogen
octogen
tetryl
UV
photo-Fenton
electrooxidation
near neutral
Opis:
Explosive compounds are hazardous to the environment, posing a serious risk to human and animal health and the ecosystem. The primary goal of research was to compare the efficiency of UV/H2O2, photo-Fenton, electro (EO)/ UV/H2O2 processes at near-neutral pH (pH=6) on the degradation of nitramine explosives (NAs), such as hexogen (RDX), octogen (HMX), and tetryl (TET), in an aqueous solution. The effect of operational conditions, likely pH of the solution, initial H2O2 concentration, initial Fe2+ concentration, and solution temperature, was observed. The removal kinetics fit with first-order kinetics and were in the order: photo-Fenton >EO/UV/ H2O2 > UV/ H2O2. The results showed higher rate constant values for TET, RDX and HMX removal by UV/ H2O2 (k = 0.07778, 0.03791 and 0.03786 min-1), EO/UV/ H2O2 (k = 0.16599, 0.1475 and 0.08674 min-1) and photo-Fenton (k = 0.18018, 0.1501 and 0.09336 min-1) processes. Furthermore, TET, RDX and HMX were mineralized at 59.7%, 45.1%, and 25.1 %, respectively, under optimum conditions after 60 min of the photo-Fenton process. From the economic perspective, photo-Fenton only requires 2.132–4.113 kWh m-3 to completely reduce NAs. Finally, acute toxicity towards Vibrio fischeri was defeated after usage of near-neutral photo-Fenton. Thus, photo-Fenton at circum-neutral is promising for low-cost, eco-friendly and efficient processes for treating nitramine explosives in aqueous solutions.
Źródło:
Journal of Ecological Engineering; 2021, 22, 6; 232-243
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Removal of Nitramine Explosives in Aqueous Solution by UV-Mediated Advanced Oxidation Process in Near-Neutral Conditions
Autorzy:
Khue, Do Ngoc
Bach, Vu Quang
Binh, Nguyen Thanh
Minh, Do Binh
Nam, Pham Thi
Loi, Vu Duc
Nguyen, Hoa Thanh
Powiązania:
https://bibliotekanauki.pl/articles/1838333.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
hexogen
octogen
tetryl
UV
photo-Fenton
electrooxidation
near neutral
Opis:
Explosive compounds are hazardous to the environment, posing a serious risk to human and animal health and the ecosystem. The primary goal of research was to compare the efficiency of UV/H2O2, photo-Fenton, electro (EO)/ UV/H2O2 processes at near-neutral pH (pH=6) on the degradation of nitramine explosives (NAs), such as hexogen (RDX), octogen (HMX), and tetryl (TET), in an aqueous solution. The effect of operational conditions, likely pH of the solution, initial H2O2 concentration, initial Fe2+ concentration, and solution temperature, was observed. The removal kinetics fit with first-order kinetics and were in the order: photo-Fenton >EO/UV/ H2O2 > UV/ H2O2. The results showed higher rate constant values for TET, RDX and HMX removal by UV/ H2O2 (k = 0.07778, 0.03791 and 0.03786 min-1), EO/UV/ H2O2 (k = 0.16599, 0.1475 and 0.08674 min-1) and photo-Fenton (k = 0.18018, 0.1501 and 0.09336 min-1) processes. Furthermore, TET, RDX and HMX were mineralized at 59.7%, 45.1%, and 25.1 %, respectively, under optimum conditions after 60 min of the photo-Fenton process. From the economic perspective, photo-Fenton only requires 2.132–4.113 kWh m-3 to completely reduce NAs. Finally, acute toxicity towards Vibrio fischeri was defeated after usage of near-neutral photo-Fenton. Thus, photo-Fenton at circum-neutral is promising for low-cost, eco-friendly and efficient processes for treating nitramine explosives in aqueous solutions.
Źródło:
Journal of Ecological Engineering; 2021, 22, 6; 232-243
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applying Electrical Impedance Tomography Techniques for Detection of Decay Inside Trees
Autorzy:
Kieu, Duy Thong
Vu, Hong Duong
Nguyen, Thi Thu Hang
Nguyen, Thu Thuy
Powiązania:
https://bibliotekanauki.pl/articles/2020936.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
electrical impedance tomography
tree investigation
resistivity
conductivity
impedancja
przewodnictwo
opór elektryczny
Opis:
Trees play a critical role in creating green spaces in public areas such as streets, parks, schools, offices. Over time, the trees often get pests and diseases, and then rotten trees can break. To care for and conserve the trees, it is necessary to determine the condition inside the trunk, especially the possibility of having a hollow or not. Wood decay, modifications of moisture and ion content, density due to biotic and abiotic stress agents of water extremity, salinity, and infection strongly change (di-) electrical properties of wood. Hence, we propose to use electrical impedance tomography to detect the change in electrical properties inside the trees that can link to wood decay. In electrical impedance tomography, an array of electrodes is attached around the tree trunk, and small alternating currents are injected via these electrodes, so the resulting voltages are measured. Processing the data, we can construct the spatial distribution of impedance (or resistivity) of the object. In this work, we will present the preliminary results of our group research. We will show theoretical forward modeling results, followed by laboratory experiments and real data application. The results illustrate that electrical impedance tomography can be useful to define several decay scenarios inside the trees.
Źródło:
Inżynieria Mineralna; 2021, 2; 31--40
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isolation of citronellal and geraniol from citronella (Cymbopogon winterianus) oil by vacuum fractional distillation: Effect of operating conditions on the separation
Autorzy:
Le, Minh-Trung
Vu, Duc-Phuong
Nguyen, Thanh Ngoc
Le, Xuan-Tien
Powiązania:
https://bibliotekanauki.pl/articles/27315670.pdf
Data publikacji:
2023
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
citronellal
geraniol
vacuum
fractional distillation
citronella oil
Opis:
This study used fractional distillation to separate citronellal and geraniol from citronella (Cymbopogon winterianus) essential oil to improve their market value. The one-factor-at-a-time methodology investigated operating parameters’ optimum conditions and effects, including system pressure, packing types, and column height. All investigations were evaluated based on their main fraction’s citronellal and geraniol content and recovery. Regarding the effect of the variables, a higher system pressure improved the separation while increasing the temperature range of each fraction and distillation time. The packing types would also improve the separation by providing a large surface area. Finally, the column height also positively impacted the separation. In the optimum citronella oil fractionation, citronellal content experienced a 2.5-fold increase, from 37.68% to 94.33%. Geraniol purity reached 40.61% from an initial content of 17.33% in the raw CW oil. The distillation could recover up to 90.00% of citronellal and 68.18% of geraniol.
Źródło:
Polish Journal of Chemical Technology; 2023, 25, 4; 67--80
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The contribution of geophysics to archaeology: a case study of an ancient canal of the Oc Eo culture in the Mekong Delta, Vietnam
Autorzy:
Le, Ngoc Thanh
Nguyen, Quang Dung
Nguyen, Quang Bac
Nguyen, Quang Mien
Nguyen, Dan Vu
Duong, Ba Man
Nguyen, Dinh Chau
Powiązania:
https://bibliotekanauki.pl/articles/184367.pdf
Data publikacji:
2019
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
electromagnetic profiling
electrical resistivity tomography
hand-auger
radiocarbon dating
ancient canal
alluvial deposits
Oc Eo culture
Ba The mountain
Opis:
Generally, underground ancient canals are infilled with alluvial materials, with the canal bed and substrate often having different resistivity values. This study aimed to determine the location and morphology of Malleret’s ancient canal 16 located to the southeast of the Ba The mountain, Mekong Delta, Vietnam by means of geophysical techniques. Two geophysical methods were used: electromagnetic profile and electric resisitivity tomography. A geoelectric structure 70 m long with 70–95 mS/m of apparent conductivity was found. On the electrical resistivity tomography section, a resistivity zone of 10–20 Ω∙m, 1–4 m deep, 70 m wide corresponds to the mentioned above geoelectric structure, which is in an asymmetric U-shape extending toward the southeastern bank of canal 16. Hand-augering confirmed that the canal bed is fully incised into Holocene sediments as a substrate which stretches down to the Pleistocene. The sediments are composed of loams mixed with plant remains with a resistivity ρ ~ 10–15 Ω∙m. Both of the canal banks at a depth of 5 m are made up of Holocene sedi-ments (ρ ~ 4–10 Ω∙m). The 14C measurements determined the age of the organic matter in the canal as being equal to 1210 ±85 BP, suggesting canal 16 ceased being operational at that time. The precise positioning of canal 16 on the ground surface, as well as identifying the morphology of the canal bed, were corroborated by geophysical techniques. The obtained results are of considerable value to archaeologists.
Źródło:
Geology, Geophysics and Environment; 2019, 45, 1; 45-56
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fracture Mechanism of Hard Main Roof and Determining the Width of Coal Pillars when Extracting Flat-lying Coal Seams
Autorzy:
Le, Quang Phuc
Dao, Van Chi
Nguyen, Phi Hung
Vu, Thai Tien Dung
Powiązania:
https://bibliotekanauki.pl/articles/27323252.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
failure mechanism
coal pillar
stress distribution
roadway deformation
retained roadway
hard main roof
gob-side entry
węgiel
filary
stabilność
Wietnam
Opis:
In underground coal mining, the stability of roadways and gob-side entry depends on the coal pillar width. An unreasonable width of the coal pillar will cause the roadway to be in a dangerous zone of influence of the abutment pressure, leading to severe roadway deformation. This paper studies the fracture mechanism of the hard main roof and reasonable coal pillar width to protect the stability of gob-side entry driving. The research results show that when mining a coal seam under a hard main roof, the console of the main roof on the edge of the coal seam has the form of hinge structure. The great load of the roof layers and the rotation of the console are the main causes leading to the variation of the stress field in the coal seam. According to the development law of the stress field, after the main roof completes the collapse process, the peak of the maximum stress will move deep into the solid coal seam, and on the edge of the coal seam it will form a low-stress zone. Research results from the case of Seam #11 of Khe Cham coal mine, Vietnam show that the gob-side entry will be well stabilized when the narrow coal pillar between it and the boundary of the gob is 4–5 m.
Źródło:
Inżynieria Mineralna; 2023, 2; 271--280
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on Suitable Mining Technology for Placer Titanium Mines in Vietnam
Dobór odpowiedniej technologii eksploatacji okruchowego tytanu w Wietnamie
Autorzy:
Le, Qui Thao
Nguyen, Hoang
Nguyen, Nga
Vu, Dinh Hieu
Le, Hoa Thu-Thi
Nguyen, Anh Thuc-Thi
Bui, Xuan‑Nam
Powiązania:
https://bibliotekanauki.pl/articles/318901.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
mining technology
placer titanium
sustainable development
Vietnam
technologia górnicza
złoże okruchowego tytanu
zrównoważony rozwój
Wietnam
Opis:
Vietnam has a potential reserve of placer titanium of around 650 Mt. The reserve lays in sandy beaches of the country from Thanh Hoa to Binh Thuan province. Placer titanium mines in Vietnam are different in geological condition, the scale of production, mining method, and environmental protection solutions, etc. Some of them are operating with inappropriate mining technology; therefore, have caused environmental issues and ineffective operation. Consequently, it is essential to have criteria for selecting appropriate mining technology to approach the sustainable development for the mines. Based on categories of geology, the scale of production, mining characteristics, requirements of safety, land reclamation and environmental protection, and mining effect, authors defined the criteria and method for selecting adequate mining technology for the placer titanium mines in Vietnam which aim for better safe, effective and sustainable. The categories to select the appropriate technology for coastal titanium placers in Vietnam including 1- feasible mining scheme, 2- mining procedure, 3- requirement volume of water, 4- slope stability, 5- environmental rehabilitation and reclamation, and 6- economic effect. The result of the application for Nam Suoi Nhum placer titanium mine in Bình Thuan province shows that the most appropriate scheme of this mine is the mining technology of using hydraulic jets, pumping and hauling by pumping mud, processing by spiral screws, and discharging by mud pumping.
Wietnam ma potencjalne rezerwy okruchowego tytanu w wysokości około 650 Mt. Rezerwat leży na piaszczystych plażach kraju od Thanh Hoa do prowincji Binh Thuan. Kopalnie okruchowego tytanu w Wietnamie różnią się stanem geologicznym, skalą produkcji, sposobem wydobycia, rozwiązaniami w zakresie ochrony środowiska itp. Niektóre z nich działają na niewłaściwej technologii wydobywczej, w związku z czym spowodowały problemy środowiskowe i nieefektywną eksploatację. W związku z tym niezbędne jest posiadanie kryteriów doboru odpowiedniej technologii wydobywczej do podejścia do zrównoważonego rozwoju. W oparciu o kategorie geologiczne, skalę produkcji, charakterystykę górniczą, wymagania bezpieczeństwa, rekultywacji gruntów i ochrony środowiska oraz efektu górniczego, autorzy określili kryteria i sposób doboru odpowiedniej technologii wydobycia dla stacjonujących kopalni tytanu w Wietnamie, które mają na celu zwiększenie bezpieczeństwa , efektywne i trwałe. Te kategorie obejmują 1- wykonalny schemat wydobycia, 2- procedurę wydobycia, 3- wymaganą ilość wody, 4- stateczność zboczy, 5-rekultywację środowiska oraz 6-efekt ekonomiczny. Wynik zastosowania dla kopalni okruchowego tytanu Nam Suoi Nhum w prowincji Bình Thuan pokazuje, że najbardziej odpowiednim schematem tej kopalni jest technologia wydobywcza wykorzystująca strumienie hydrauliczne, pompowanie i ciągnięcie przez pompowanie szlamu, przetwarzanie za pomocą śrub spiralnych i odprowadzanie przez pompowanie błota.
Źródło:
Inżynieria Mineralna; 2020, 1, 2; 75-86
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation of length to beam ratio effects on ship resistance using ranse method
Autorzy:
Le, Tat Hien
Nguyen, Duy Anh
Tran, Ngoc Tu
Hoa, Nguyen Thi Ngọc
Ngoc, Vu Minh
Powiązania:
https://bibliotekanauki.pl/articles/32917972.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
length-beam ratio
L/B
resistance
hull form
RANSE
Opis:
The paper discusses the length to beam (L/B) ratio effects on ship resistance at three different Froude numbers using unsteady RANSE simulation. First, the JBC ship model was used as an initial hull form for verification and validation of predicted ship resistance results with measured data, and then the influence of the L/B ratio on ship resistance was carried out. Ship hull forms with different L/B ratios were produced from the initial one by using the Lackenby method. The numerical results obtained show the L/B ratio’s effect on ship resistance. Increases of the L/B ratio led to gradual reduction of the total ship resistance and vice versa. Analysis of the changing of the resistance components indicates that the pressure resistance changes are considerably larger than the frictional one. Finally, the paper analyses the difference in the flow field around the hull of the ship with variation of the L/B ratio to fully understand the physical phenomenon in the change of ship resistance at different L/B parameters.
Źródło:
Polish Maritime Research; 2023, 1; 13-24
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł

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