Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "Nguyen, Duc Anh" wg kryterium: Autor


Tytuł:
SIoT Framework: Towards an Approach for Early Identification of Security Requirements for Internet-of-things Applications
Autorzy:
Jabangwe, Ronald
Nguyen-Duc, Anh
Powiązania:
https://bibliotekanauki.pl/articles/384191.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
security requirement
Internet-of-things
software engineering
requirement engineering
security framework
Opis:
Background: Security has become more of a concern with the wide deployment of Internet-of-things (IoT) devices. The importance of addressing security risks early in the development lifecycle before pushing to market cannot be over emphasized. Aim: To this end, we propose a conceptual framework to help with identifying security concerns early in the product development lifecycle for Internet-of-things, that we refer to as SIoT (Security for Internet-of-Things). Method: The framework adopts well known security engineering approaches and best practices, and systematically builds on existing research work on IoT architecture. Results: Practitioners at a Norwegian start-up company evaluated the framework and found it useful as a foundation for addressing critical security concerns for IoT applications early in the development lifecycle. The output from using the framework can be a checklist that can be used as input during security requirements engineering activities for IoT applications. Conclusions: However, security is a multi-faced concept; therefore, users of the SIoT framework should not view the framework as a panacea to all security threats. The framework may need to be refined in the future, particularly to improve its completeness to cover various IoT contexts.
Źródło:
e-Informatica Software Engineering Journal; 2020, 14, 1; 77-95
1897-7979
Pojawia się w:
e-Informatica Software Engineering Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Do Software Firms Collaborate or Compete? A Model of Coopetition in Community-initiated OSS Projects
Autorzy:
Nguyen-Duc, Anh
Cruzes, Daniela S.
Terje, Snarby
Abrahamsson, Pekka
Powiązania:
https://bibliotekanauki.pl/articles/384189.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
COSS
coopetition
collaboration
competition
open source software
case study
Opis:
Background: An increasing number of commercial firms are participating in Open Source Software (OSS) projects to reduce their development cost and increase technical innovativeness. When collaborating with other firms whose sought values are conflicts of interests, firms may behave uncooperatively leading to harmful impacts on the common goal. Aim: This study explores how software firms both collaborate and compete in OSS projects. Method: We adopted a mixed research method on three OSS projects. Result: We found that commercial firms participating in community-initiated OSS projects collaborate in various ways across the organizational boundaries. While most of firms contribute little, a small number of firms that are very active and account for large proportions of contributions. We proposed a conceptual model to explain for coopetition among software firms in OSS projects. The model shows two aspects of coopetition can be managed at the same time based on firm gatekeepers. Conclusion: Firms need to operationalize their coopetition strategies to maximize value gained from participating in OSS projects.
Źródło:
e-Informatica Software Engineering Journal; 2019, 13, 1; 37-62
1897-7979
Pojawia się w:
e-Informatica Software Engineering Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Delay factors in the construction of irrigation and hydropower projects in Vietnam
Autorzy:
Nguyen, Van Son
Nguyen, Huu Hue
Nguyen, Duc Anh
Hai, Dinh Tuan
Powiązania:
https://bibliotekanauki.pl/articles/2203414.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hydroenergetyka
nawadnianie
konstrukcja
zarządzanie projektem
współczynnik opóźnienia
Wietnam
hydropower
irrigation
construction
project management
delay factor
Vietnam
Opis:
Irrigation and hydropower are among the most important sectors in the construction industry that propel the economic needs of a developing country like Vietnam. The construction of these projects often suffers from severe delays, leading to financial losses and other negative impacts on the economy. This paper aims to determine delay factors in the construction of these projects. Among many, 39 most important candidates of delay causes were identified from the literature review. Further surveys on project participants were conducted for the severity of these causes. An exploratory factor analysis was utilized to identify latent factors that cause delays in construction projects. The analysis result categorized a few groups of factors such as abnormal factors on the construction site (e.g., labor accidents, hydrology, water flow, extreme weather) and technical factors related to the construction contractor (e.g., unsuitable schedule, outdated construction technology, unprofessional workers) that have the greatest impact on the delay in construction of irrigation and hydropower projects in Vietnam. These findings contribute to the body of knowledge of project management and risk management, hence an improvement in the efficiency of the project sectors’ performance.
Źródło:
Archives of Civil Engineering; 2023, 69, 1; 5--20
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling labor productivity in high-rise building construction projects using neural networks
Autorzy:
Nguyen, Duc Anh
Tran, Dung Quang
Nguyen, Thoan Ngoc
Tran, Hai Hong
Powiązania:
https://bibliotekanauki.pl/articles/2203438.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
Labor productivity in building construction has long been a focused research topic due to the high contribution of labor cost in the building total costs. This study, among a few studies that used scaled data that were collected directly from measuring equipment and onsite activities, utilized neural networks to model the productivity of two main construction tasks and influencing factors. The neural networks show their ability to predict the behaviors of labor productivity of the formwork and rebar tasks in a test case of a high-rise building. A multilayer perceptron that had two layers and used sigmoid as its activation function provided the best effectiveness in predicting the relations among data. Among eleven independent factors, weather (e.g., temperature, precipitation, sun) generally played the most important role while crew factors were distributed in the mid of the ranking and the site factor (working floor height) played a mild role. This study confirms the robustness of neural networks in productivity research problems and the importance of working environments to labor productivity in building construction. Managerial implications, including careful environmental factors and crew structure deliberation, evolved from the study when labor productivity improvement is considered.
Źródło:
Archives of Civil Engineering; 2023, 69, 1; 675--692
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Robust H∞ fuzzy approach design via Takagi‐Sugeno descriptor model. application for 2‐DOF serial manipulator tracking control
Autorzy:
Thi, Van Anh Nguyen
Pham, Duc Binh
Nguyen, Danh Huy
Nguyen, Tung Lam
Powiązania:
https://bibliotekanauki.pl/articles/27314207.pdf
Data publikacji:
2022
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
tracking control
serial manipulator robot
fuzzy control
Takagi-Sugeno
Lyapunov stability
Opis:
This paper focuses on trajectory tracking control for ro‐ bot manipulators. While much research has been done on this issue, many other aspects of this field have not been fully addressed. Here, we present a new solution using feedforward controller to eliminate parametric uncer‐ tainties and unknown disturbances. The Takagi‐Sugeno fuzzy descriptor system (TSFDS) is chosen to describe the dynamic characteristics of the robot. The combination of this fuzzy system and the robust H∞ performance makes the system almost isolated from external factors. The li‐ near matrix inequalities based on the theory of Lyapunov stability is considered for control design. The proposed method has proven its effectiveness through simulation results.
Źródło:
Journal of Automation Mobile Robotics and Intelligent Systems; 2022, 16, 3; 22--29
1897-8649
2080-2145
Pojawia się w:
Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new chemical mechanical slurry for polishing yttrium aluminium garnet material with magnesium oxide, sodium metasilicate pentahydrate and zirconium dioxide abrasive particles
Autorzy:
Duc, Le Anh
Hieu, Pham Minh
Quang, Nguyen Minh
Powiązania:
https://bibliotekanauki.pl/articles/24084631.pdf
Data publikacji:
2023
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
chemical-mechanical polishing
yttrium aluminum garnet
magnesium oxide
abrasive particles
Opis:
This work provided a new chemical-mechanical polishing mixture with MgO, sodium metasilicate pentahydrate, ZrO2 abrasive particles, and deionized water. With chemical-mechanical slurry (CMS) proposed for polishing yttrium aluminum oxide (Y3Al5O12) the surface reaction layer formed with significantly reduced hardness compared to other Y3Al5O12 materials, these products combine with MgO to form montmorillonites (3MgO–Al2O3–3SiO2–3Y2O3–5Al2O3). With this formation, the surface layer of Y3Al5O12 material becomes soft and is easily removed by ZrO2 abrasive particles under the influence of mechanical polishing, resulting in superfine surfaces generated from the proposed CMS model. The experimental results show that the surface quality with CMS proposed gives the surface quality with Ra = 0.471 nm along with the material removal rate 31 (nm/min). Surface quality is improved by 71% along with a superior material removal rate (increased by 287%) compared to silica slurry. The results show excellent polishing ability from CMS proposed for polishing Y3Al5O12 materials.
Źródło:
Journal of Machine Engineering; 2023, 23, 2; 174--185
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Community participation for developing rural transport infrastructure in Dong Nai province, Vietnam
Autorzy:
Hai, Dinh Tuan
Quyet, Nguyen Xuan
Nguen, Duc Anh
Powiązania:
https://bibliotekanauki.pl/articles/2098152.pdf
Data publikacji:
2021
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
community
Dong Nai
infrastructure
transport
Vietnam
społeczność
infrastruktura
Wietnam
Opis:
Developing countries are facing sustainability problems in developing rural transport infrastructure; the problems arise from the lack of financial resource and public support. Enhancing community participation promises to resolve these challenges. Demographics has a strong influence on community participation; however, how demographic characteristics interact with community participation has been yet to be focally studied. Dong Nai, a southern province in Vietnam, was selected as the case study owing to its high requirement of rural transport infrastructure. Questionnaires were sent to 438 households. An analysis of data was performed descriptively and with logistic regression. Community participation was recorded as financial, labor, material, and land contribution. Household composition, education, income, and member in household as community leader are among the highest influential factors to community participation. With the importance of community participation, the results of the study benefits both policy makers and local governments in planning, predicting the success of local development programs, and enhancing community participation, which increase the chance of success in rural transport infrastructure.
Źródło:
Transport Problems; 2021, 16, 2; 45--57
1896-0596
2300-861X
Pojawia się w:
Transport Problems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Developing the Regression Equations to Determine the Bankfull Discharge from the Basin Characteristics
Autorzy:
Chau, Tran Kim
Toan, Nguyen The
Duc, Do Anh
Linh, Nguyen Ha
Powiązania:
https://bibliotekanauki.pl/articles/2097760.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
bankfull discharge
regression equation
catchment characteristics
Opis:
Bankfull discharge is an important criterion for flash flood warnings. In this study, the authors propose a new approach to determine the bankfull discharge for basins in Ha Giang province, Vietnam. The study combines the field survey to determine the bankfull discharge through the bankfull indicators and develop a multivariate regression equation between the bankfull discharge and the basin characteristics. The results of the study give a simple equation with 2 independent variables. They are the catchment area and the main river length. They show a strong relationship with the bankfull discharge with the R2 indexes in developing and validating process equal to 95.3% and 92.7%, respectively. With this approach, the workload is significantly reduced. However, the accuracy and flexibility of the total discharge calculation are enhanced. This will be the foundation to reduce uncertainty in flash flood warnings.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2021, 68, 2; 103--117
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Google Search intensity and stock returns in frontier markets: Evidence from the Vietnamese market
Autorzy:
Duc, Dang Thi Viet
Hoai, Nguyen Thu
Nguyen, Van Phuoc
Nguyen, Dang Phong
Anh, Nguyen Huong
Hai, Ho Hong
Powiązania:
https://bibliotekanauki.pl/articles/51476161.pdf
Data publikacji:
2024
Wydawca:
Uniwersytet Ekonomiczny w Poznaniu. Wydawnictwo Uniwersytetu Ekonomicznego w Poznaniu
Tematy:
Google search
Vietnam
COVID-19
investor attention
search intensity
stock returns
frontier markets
Opis:
The study investigates investor attention's impact on stock trading by modeling the relationship between Google search intensity and stock return with stocks listed in frontier markets in Vietnam from October 2016 to October 2021. The study has three findings. First, the study confirms the price pressure hypothesis and attention theory that Google search intensity positively affects stock returns. Second, this study indicates that the impact of Google search intensity on stock price is short. The positive effect is within the week of searching and reverses the following week, although the reverse force is not strong. Third, the relationship is more robust post than pre-COVID-19, suggesting that after a shock, more new individual investors enter the market, the impact of GSVI on stock return is stronger.
Źródło:
Economics and Business Review; 2024, 10, 1; 30-56
2392-1641
Pojawia się w:
Economics and Business Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of Heavy Metal Pollution in the Surface Water of the Doi-Cho Dem-Ben Luc Rivers, Vietnam
Ocena zanieczyszczenia metalami ciężkimi wód powierzchniowych rzek Doi-Cho Dem-Ben Luc w Wietnamie
Autorzy:
Thieu, Van Vu Duc
Dinh, Thi Thu Huong
Nguyen, Thi Truc Thao
Nguyen, Thuy Lan Chi
Nguyen, Binh An
Pham, Anh-Duc
Powiązania:
https://bibliotekanauki.pl/articles/2172069.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
heavy metal pollution
surface water
distribution
river
Doi-Cho Dem-Ben Luc
water quality protection
zanieczyszczenie metalami ciężkimi
wody powierzchniowe
dystrybucja
rzeki
ochrona jakości wód
Opis:
Heavy metals are a pressing concern in terms of their pollution in aquatic ecosystems because of their persistence, environmental toxicity, bioaccumulation. Aquatic environments receive heavy metals in untreated or inadequately treated wastewater from domestic, industrial, agricultural, and navigation sources. The Doi-Cho Dem-Ben Luc Rivers play the key roles of irrigation, navigation and ecological restoration. It is crucial to ascertain the pollution status, influencing factors, ecological risks, and possible sources of heavy metals in the surface water of the Doi-Cho Dem-Ben Luc Rivers. In this study, surface water from 7 sampling sites over was collected from the Doi-Cho Dem-Ben Luc Rivers, over 7 consecutive periods from April 2019 to October 2021. Each surface sample was analyzed for 9 heavy metals including Fe, Mn, Cr, Zn, Cu, Pb, Cd, Ni, As. The sampling technique and sample treatment were done based on the Standard Methods for the Examination of Water and Wastewater. The time and space variation of heavy metal concentrations were examined to test the analysis of variance (ANOVA) and correlation among all the parameters using R statistical software. The results suggest a spatial homogeneity of heavy metals in the surface water the studied rivers. Among all nine examined heavy metals in the studied area, the concentrations of Fe (1.00 ÷ 5.06 mg/L) and Mn (0.14 ÷ 0.28 mg/L) are the highest, and the concentrations of Cr, Cd and As are the lowest that lower limit of detection. The results suggested that the mean concentrations of Fe and Mn were above the acceptable limits of the National technical regulation on surface water quality (QCVN 08-MT: 2015/BTNMT). While the concentrations of Fe, Mn, Zn, Cu, Pb, Ni do not meet the Water quality criteria for aquatic life (United State Environmental Protection Agency). Anthropogenic activities can be the main source of heavy metals in in the surface water of the Doi-Cho Dem-Ben Luc Rivers. Among the heavy metals, a significant positive correlation was observed between Fe, Mn, Zn and Ni (0.64 ÷ 0.87), whereas Cu exhibited a significant positive correlation with Ni (0.51). While Cu and Pb showed a not too strong correlation with Fe, Mn, Zn and Ni (0.25 ÷ 0.48). The distribution of heavy metals may also be influenced by properties of heavy metals and fluctuations in water flows. The results provide guidance for controlling heavry metal pollution and protectting water sources in the Doi-Cho Dem-Ben Luc Rivers.
Metale ciężkie stanowią palący problem zanieczyszczenia w ekosystemach wodnych ze względu na ich trwałość, toksyczność dla środowiska i bioakumulację. Środowiska wodne sa zasilane w metale ciężkie z nieoczyszczonych lub nieodpowiednio oczyszczonych ścieków ze źródeł domowych, przemysłowych, rolniczych i żeglugowych. Rzeki Doi-Cho Dem-Ben Luc odgrywają kluczową rolę w nawadnianiu terenów, transporcie odnym i odbudowie ekologicznej. Kluczowe znaczenie ma ustalenie stanu zanieczyszczenia, czynników wpływających, zagrożeń ekologicznych i możliwych źródeł metali ciężkich w wodach powierzchniowych rzek Doi-Cho Dem-Ben Luc. W artykule przedstawiono wyniki badania wód powierzchniowych, próbki pobrano z 7 punktów pomiarowych z rzek Doi-Cho Dem-Ben Luc przez 7 kolejnych okresów od kwietnia 2019 r. do października 2021 r. Każda próbka została przeanalizowana pod kątem zawartości 9 metali ciężkich: Fe, Mn, Cr , Zn, Cu, Pb, Cd, Ni, As. Metodyka pobierania próbek i obróbki próbek zostały opracowane w oparciu o Standardowe Metody Badania Wód i Ścieków. Zbadano zmienność w czasie i przestrzeni stężeń metali ciężkich, do analizyy wyników wykorzystano analizę wariancji (ANOVA) i korelacji między wszystkimi parametrami przy użyciu oprogramowania statystycznego. Wyniki sugerują przestrzenną jednorodność zawartości metali ciężkich w wodach powierzchniowych badanych rzek. Spośród wszystkich dziewięciu badanych metali ciężkich w badanym terenie najwyższe są stężenia Fe (1,00 ÷ 5,06 mg/L) i Mn (0,14 ÷ 0,28 mg/L), a najniższe Cr, Cd i As (wartości odpowiadające dolnej granicy wykrywalności). Wyniki wskazują, że średnie stężenia Fe i Mn były powyżej dopuszczalnych limitów, opisanych w krajowych normach dotyczących jakości wód powierzchniowych (QCVN 08-MT: 2015/BTNMT). Natomiast stężenia Fe, Mn, Zn, Cu, Pb, Ni nie spełniają kryteriów jakości wody dla organizmów wodnych (Agencja Ochrony Środowiska Stanów Zjednoczonych). Działalność antropogeniczna może być głównym źródłem metali ciężkich w wodach powierzchniowych rzek Doi-Cho Dem-Ben Luc. Wśród metali ciężkich zaobserwowano istotną dodatnią korelację między zawartością Fe, Mn, Zn i Ni (0,64 ÷ 0,87), natomiast Cu wykazywała istotną dodatnią korelację z Ni (0,51). Zawartości Cu i Pb wykazywały niezbyt silną korelację z Fe, Mn, Zn i Ni (0,25 ÷ 0,48). Na rozmieszczenie metali ciężkich mogą mieć również wpływ właściwości metali ciężkich oraz wahania przepływów wody. Wyniki dostarczają wskazówek dotyczących kontrolowania zanieczyszczenia metalami ciężkimi i ochrony źródeł wody w rzekach Doi-Cho Dem-Ben Luc.
Źródło:
Inżynieria Mineralna; 2022, 2; 85--90
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of solid and ionic surface reaction form to surface quality when using chemical-mechanical slurry polishing
Autorzy:
Duc, Le Anh
Hieu, Pham Minh
Mai, Nguyen Trong
Trong, Thai Van
Quang, Nguyen Minh
Powiązania:
https://bibliotekanauki.pl/articles/2171776.pdf
Data publikacji:
2022
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
chemical-mechanical slurry
polishing
abrasive particle
ionic surface reaction
yttrium aluminum garnet
surface roughness
Opis:
The process of removing machining residues using chemical-mechanical slurry (CMS) has an important place in the creation of ultra-precise components in optical devices. Based on this feature, this work investigates the efficiency of the CMS polishing process by comparing the surface reaction modes by the ionic and solid reaction modes when polishing the yttrium aluminum garnet (YAG) and sapphire crystal. The study procedures were conducted to clarify the polishing performance corresponding to these two reaction types. The obtained experiments results show that the balance between the mechanical effect process using CMS polishing technology with chemical effect can be achieved with the ionic reaction mode. The results also show that the ionic surface reaction modes give more uniform material removal than the solid reaction on YAG and sapphire crystal surfaces. Therefore, the surface quality when polished by CMS technology with ionic surface reaction modes is better than that of solid surface reaction.
Źródło:
Journal of Machine Engineering; 2022, 22, 4; 82--94
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of geometrical parameters of plastic bottle shredder blade utilizing a two-step optimization method
Autorzy:
Nguyen, Trieu Khoa
Chau, Minh Quang
Do, The-Can
Pham, Anh-Duc
Powiązania:
https://bibliotekanauki.pl/articles/1845034.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
plastic waste
shredder blade
two-step optimization
Taguchi method
response surface method
odpady z tworzyw sztucznych
optymalizacja dwustopniowa
metoda Taguchi
metoda powierzchni odpowiedzi
Opis:
In this paper, a numerical and experimental investigation of geometrical parameters of the blade for plastic bottle shredder was performed based on the Taguchi method in combination with a response surface method (RSM). Nowadays, plastic waste has become a major threat to the environment. Shredding, in which plastic waste is shredded into small bits, ready for transportation and further processing, is a crucial step in plastic recycling. Although many studies on plastic shredders were performed, there was still a need for more researches on the optimization of shredder blades. Hence, a numerical analysis was carried out to study the influences of the relevant geometrical parameters. Next, a two-step optimization process combining the Taguchi method and the RSM was utilized to define optimal parameters. The simulation results clearly confirmed that the current technique can triumph over the limitation of the Taguchi method, originated from a discrete optimization nature. The optimal blade was then fabricated and experimented, showing lower wear via measurement by an ICamScope® microscope. Hence, it can be clearly inferred from this investigation that the current optimization method is a simple, sufficient tool to be applied in such a traditional process without using any complicated algorithms or expensive software.
Źródło:
Archive of Mechanical Engineering; 2021, LXVIII, 3; 253-269
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applying Artificial Pillar to Replace the Coal Pillar Protecting Roadway to Increase Production Efficiency and Sustainable Development in the Vietnamese Coal Industry
Autorzy:
Dinh, Van Cuong
Nguyen, Anh Tuan
Tran, Van Thanh
Nguyen, Thi Hoai Nga
Duong, Duc Hai
Powiązania:
https://bibliotekanauki.pl/articles/2020898.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
coal pillar protecting roadways
coal loss
artificial pillar
underground mine
filary węglowe
górnictwo podziemne
ubytki węgla
Opis:
Vietnam's domestic coal production is growing fast and is expected to reach 68.9 million tons in 2030, nearly 1.5 times higher than today. Open-pit mines will gradually reduce production and close, and underground mining coal output will increase progressively year by year and take a leading role. Besides the investment in new mines to achieve these goals, it is necessary to maximize the coal reserve exploited annually of existing underground mine projects, which its coal reserve in pillars protecting roadways currently accounts for 12−15%. The further exploitation of this coal reserve will decrease the costs of preparation of underground mines and granting mining rights and depreciation of infrastructure assets. Moreover, it will help reduce the loss of non-renewable resources and contributing to the sustainable development of Vietnam’s coal industry.
Źródło:
Inżynieria Mineralna; 2021, 2; 587--597
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aquatic Invertebrates and Their Correlation with Environmental Parameters in Coastal of Tien Giang Province, Mekong Delta in Vietnam
Bezkręgowce wodne i ich korelacja z parametrami środowiska na wybrzeżu prowincji Tien Giang, delta Mekongu w Wietnamie
Autorzy:
Nguyen, Thuy Lan Chi
Dang, Thi Cam Tu
Nguyen, Thi Ha
Nguyen, Binh An
Pham, Anh-Duc
Huynh, Phuc Lo
Powiązania:
https://bibliotekanauki.pl/articles/2172063.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
coastal area
aquatic invertebrates
physicochemical parameters
relationships
water quality assessment
obszary przybrzeżne
bezkręgowce wodne
parametry fizykochemiczne
zależności
ocena jakości wody
Opis:
The Tien Giang province is located in the tropical climate zone of the Mekong delta. The climate here is clearly divided into two main seasons, namely wet season and dry season and the average temperature is about 27°C. The coastline is 32 kilometers (20 mi) long with thousands of coastal warp, which is an advantage for aquatic breeding such as crab and sea-based economy development. Aquatic invertebrates are a diverse group of organisms that inhabit coastal area throughout the world, in regions spanning alpine, arid, Mediterranean, polar, temperate, and tropical climates. Estuarine coastal invertebrates include benthic, planktonic, and stygobitic taxa and range from widespread taxa to water quality assessment. Classified by size as either macroinvertebrates or smaller meiofauna, macroinvertebrates are more widely studied, although meiofauna can also be diverse and abundant in aquatic communities. The influence of environmental factors on the diversity of invertebrates was studied in the Tien Giang Coastal Area, Southern Vietnam. The study was done between March 2019 and September 2021, encompassing both dry and rainy seasons. Data from 10 sites were used as a representative example for the Tien Giang Coastal Area to conduct a qualitative study. To implement this evaluation, the analyses were based on MRC methods and classifications these improved by the scientific group. The biological and environmental variables were examined to test the analysis of variance (ANOVA) and the Pearson correlation among all the parameters using R statistical software. Significant or highly significant positive or negative correlations were assumed when the p-calculated value was < 0.05 or 0.01, respectively. The results of the assessment showed that 32 species of zooplankton and 18 species of benthic macroinvertebrates were found in the study area. The density of zooplankton at each site ranged from 6 to 85 individuals/sample, while the density of benthic macroinvertebrates at each site fluctuated from 4 to 15 individuals/sample. The calculated values for the diversity index (H’) of both zooplankton and benthic macroinvertebrates fluctuated at the average level (H’ ≈ 1.00 ÷ 1.72). The results also show that several environmental variables, including total suspended solid, chemical oxygen demand, and ammonium were correlated with species richness and density of aquatic invertebrates. The obtained results will be useful for the monitoring of pollution status at the study area in particular the sensitivity of aquatic invertebrates to changes of environmental characteristics.
Prowincja Tien Giang położona jest w strefie klimatu zwrotnikowego delty Mekongu. Klimat jest tutaj wyraźnie podzielony na dwie główne pory roku, a mianowicie porę deszczową i porę suchą, a średnia temperatura wynosi około 27°C. Linia brzegowa ma 32 kilometry (20 mil) długości i bardzo urozmaiconą linię brzegową, co jest zaletą dla hodowli wodnych, takich jak kraby i rozwój gospodarki morskiej. Bezkręgowce wodne to zróżnicowana grupa organizmów zamieszkujących obszary przybrzeżne na całym świecie, w regionach obejmujących klimat alpejski, suchy, śródziemnomorski, polarny, umiarkowany i tropikalny. Bezkręgowce przybrzeżne ujść rzek obejmują taksony bentosowe, planktonowe i stygobitowe, od szeroko rozpowszechnionych taksonów do oceny jakości wody. Klasyfikowane według wielkości jako makrobezkręgowce lub mniejsza meiofauna, makrobezkręgowce są szerzej badane, chociaż meiofauna może być również różnorodna i obfita w społecznościach wodnych. Wpływ czynników środowiskowych na różnorodność bezkręgowców badano na obszarze przybrzeżnym Tien Giang w południowym Wietnamie. Badanie zostało przeprowadzone w okresie od marca 2019 do września 2021, obejmując zarówno porę suchą, jak i deszczową. Dane z 10 miejsc wykorzystano jako reprezentatywny przykład dla obszaru przybrzeżnego Tien Giang do przeprowadzenia badania jakościowego. Aby przeprowadzić tę ocenę, analizy oparto na metodach MRC i klasyfikacjach, które zostały udoskonalone przez grupę naukową realizującą badania. Badano zmienne biologiczne i środowiskowe w celu przetestowania analizy wariancji (ANOVA) i korelacji Pearsona R między wszystkimi parametrami przy użyciu oprogramowania statystycznego. Przyjęto znaczące lub bardzo istotne dodatnie lub ujemne korelacje, gdy obliczona wartość p wynosiła odpowiednio <0,05 lub 0,01. Wyniki oceny wykazały, że na badanym obszarze stwierdzono występowanie 32 gatunków zooplanktonu i 18 gatunków makrobezkręgowców bentosowych. Zagęszczenie zooplanktonu na każdym stanowisku wahało się od 6 do 85 osobników/próbę, podczas gdy zagęszczenie makrobezkręgowców bentosowych na każdym stanowisku wahało się od 4 do 15 osobników/próbę. Obliczone wartości wskaźnika różnorodności (H’) zarówno zooplanktonu, jak i makrobezkręgowców bentosowych oscylowały na średnim poziomie (H’ ≈ 1,00 ÷ 1,72). Wyniki pokazują również, że kilka zmiennych środowiskowych, w tym całkowita zawiesina, chemiczne zapotrzebowanie tlenu i amon, było skorelowanych z bogactwem gatunkowym i gęstością bezkręgowców wodnych. Uzyskane wyniki będą przydatne do monitorowania stanu zanieczyszczenia badanego obszaru, w szczególności wrażliwości bezkręgowców wodnych na zmiany cech środowiska.
Źródło:
Inżynieria Mineralna; 2022, 2; 99--103
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design optimization of compliant mechanisms for vibration assisted machining applications using a hybrid Six Sigma, RSM-FEM, and NSGA-II approach
Autorzy:
Pham, Huy-Tuan
Nguyen, Van-Khien
Dang, Quang-Khoa
Duong, Thi Van Anh
Nguyen, Duc-Thong
Phan, Thanh-Vu
Powiązania:
https://bibliotekanauki.pl/articles/24084644.pdf
Data publikacji:
2023
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
compliant mechanism
multi-objective optimisation
Six Sigma
NSGA-II
Opis:
Vibration-assisted machining, a hybrid processing method, has been gaining considerable interest recently due to its advantages, such as increasing material removal rate, enhancing surface quality, reducing cutting forces and tool wear, improving tool life, or minimizing burr formation. Special equipment must be designed to integrate the additional vibration energy into the traditional system to exploit those spectacular characteristics. This paper proposes the design of a new 2-DOF high-precision compliant positioning mechanism using an optimization process combining the response surface method, finite element method, and Six Sigma analysis into a multi-objective genetic algorithm. The TOPSIS method is also used to select the best solution from the Pareto solution set. The optimum design was fabricated to assess its performance in a vibration-assisted milling experiment concerning surface roughness criteria. The results demonstrate significant enhancement in both the manufacturing criteria of surface quality and the design approach criteria since it eliminates modelling errors associated with analytical approaches during the synthesis and analysis of compliant mechanisms.
Źródło:
Journal of Machine Engineering; 2023, 23, 2; 135--158
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies