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Wyświetlanie 1-11 z 11
Tytuł:
A New Approach on Improving The Operation of Over-Current Relays in 6kV Mining Grids of QuangNinh, VietNam
Autorzy:
Bun, Ho Viet
Thanh, Le Xuan
Powiązania:
https://bibliotekanauki.pl/articles/24200705.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
over-current relays
open-pitch mines
instantaneous time characteristic
false trip
Time Multiplayer Setting
Opis:
Over-current relays (OCR) are the most popular protecting devices utilized in 6kV mining grids of open-pitch mines, QuangNinh province, VietNam. Depending on time of operation of OCR, there are many operating mode catergorized as: Instantaneous OCR, Inverse time OCR, Inverse definite minimum time (IDMT) OCR, Very invese relays, Extremely Inverse relays. Nowaday, to give protection against: Phase faults, Earth faults, Winding faults (in transformer), most of mining companies using Over-current relays with instantaneous characteristic. This charactersitic has the following important features: i) Operates in a definite time when current exceed relay’s pick-up/setting up values, ii) Relay’s operation is mainly relied on current magnitude, iii) Operating time is constant, iv) There isn’t any intentional time delay, v) The operating currents are progressively increased for the other relays when moving towars the source. Apart from many advantages, there is a significant disavantage of the relays’s operation: when there are faults at the beginning of feeders, OCR with instantaneous characteristic usually has a big-time tripping. Moreover, sometimes there are false trip of OCR because of improper set-up. In this study, an offline method is proposed with simulation in ETAP software to overcome these issues. With Gurobi-Optimizer application, an algorithm for identifying Time Multiplayer Setting (TMS) will be employed to generate inversetime characteristic/inverse definite minimum time charactersitic for improving the performance of over-current relay with better discriminative tripping. The proposed method is simulated on ETAP with a 6kV sample skeleton distribution network (in QuangNinh province of VietNam). The demonstrating results are: the prevention of false trip of OCR and the operating time of OCR is reduced.
Źródło:
Inżynieria Mineralna; 2023, 2; 29--38
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determining the Correction Factors of OverheadConductors in 6kV Mining System of QuangNinh, VietNam with the Consideration of Power Harmonic Impact
Autorzy:
Giang, Vu Hoang
Thanh, Le Xuan
Powiązania:
https://bibliotekanauki.pl/articles/25212175.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
medium voltage grid
skin effect
correction factor
algorithm
górnictwo
Wietnam
maszyny elektryczne
Opis:
Understanding the impact of power harmonic on energy transmission play an important role not only in the operation process but also in the designing procedure of MV grid. In 6kV mining grids of Vietnamese coal mines, because of rapidly utilizing the power electronic machines, the power quality violation occurs very frequently. This lead to many disadvantages such as: the increase of power losses, voltage distortion, over-heating in transformers and conductors. Moreover, the presence of power harmonic bring the bad impact of skin effect and proximity on conductor including overhead-conductors and cables. The actual operation exhibits that the losses of transmission lines are approximately over 50% of total network losses. If there are power quality violation, this amount could be higher. Basing on investigating the fact of power harmonic violations in 6kV grid of both underground and surface mines, the paper will analyze this kind of impact. An algorithm relying on Matlab programming is used to calculate the energy losses. Results are compared with on-site measurement datas and lab-measurement to obtain series of correction factors corresponding to individual line’s cross section. The outcomes of research could be applicable for power utilities to have better analysis in the designing stage of mining MV grids.
Źródło:
Inżynieria Mineralna; 2023, 2; 71--78
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improving the operation of earth fault relays by auto earthing-connection at earth fault situations in 6kV mining grid of Quang Ninh
Poprawa działania przekaźników ziemnozwarciowych poprzez automatyczne połączenie uziemiające w sieci górniczej 6kV w Quang Ninh
Autorzy:
Bun, Ho Viet
Thanh, Le Xuan
Powiązania:
https://bibliotekanauki.pl/articles/318091.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
górnictwo
Wietnam
przekaźniki
mining
Vietnam
grids
Opis:
Single phase earth-fault in MV grids usually causes overvoltage that harm to human being and electric equipments. In 6kV mining grids of Vietnam, earth fault which is majority incident accounts 55% to 73% of the total faults. When earth fault occurs many grids’ eco-technical parameters will be affected. Moreover, the overvoltage and earthing current can lead to serious electric shock accidents caused mainly by stepping-overvoltage or touching-overvoltage. One of earthing relays requirements is to trip in minimum time duration in order to reduce the magnitude of earthing currents and overvoltage. Base on the simulation in Matlab, the paper suggests a prior connection diagram that allows an auto earthing-connection for improving the better performance of relays. The utilization of the diagram will help to decrease the tripping time of relays, reduce the amplitude of internal overvoltage as well as enhance the safety for human being in case of earthing incidents.
Źródło:
Inżynieria Mineralna; 2019, 21, 2/2; 52-57
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Developing a Set of Criteria for Prioritising GHG Emission Reduction Measures in Metallurgical Sector
Opracowanie zestawu kryteriów ustalania priorytetów środków redukcji emisji gazów cieplarnianych w sektorze metalurgicznym
Autorzy:
Tran, Xuan Truong
Tran, Thanh Ha
Le, Thanh Nghi
Nguyen, Nhu Hung
Do, Thi Thanh Nga
Vuong, Xuan Hoa
Powiązania:
https://bibliotekanauki.pl/articles/318093.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
prioritising mitigation measures
Delphi method
metallurgical sector
priorytetyzacja działań łagodzących
metoda Delphi
sektor metalurgiczny
Opis:
Prioritizing climate change mitigation measures could help to identify most feasible or most nationally appropriated mitigation actions. This process can also provide important inputs for the development of national climate change strategies or policies. The paper applies Delphi method to prioritize criteria for potential climate change mitigation technology in the metallurgical sector in Vietnam. The consultation process has been done with ten experts in only two cycle to reach Kendall (W) value over 0.5. Then, 11 out of 21 criteria have been selected for Multi-Criteria Decision Analysis (MCDA) in prioritizing mitigation options in iron and steel, lead, zinc, tin and aluminium productions. Mitigation options with highest scores will be proposed for mitigation target of the metallurgical sector which could be inputs for NDC of industrial sector. The selected criteria include 01 indicator in emission reduction (GPT1), 01 indicator in environmental impacts (MT1), 01 indicators in social impacts (XH3), 02 indicators in economic impacts (KT1, KT2), 02 indicators in sustainable development impacts (PTBV1, PTBV2) and 04 indicators in MRV (MRV1, MRV2, MRV3, MRV4).
Nadanie priorytetu środkom łagodzenia zmiany klimatu może pomóc w zidentyfikowaniu najbardziej wykonalnych lub najbardziej odpowiednich na szczeblu krajowym działań łagodzących. Proces ten może również stanowić ważny wkład w rozwój krajowych strategii lub polityk w zakresie zmian klimatu. W artykule, zastosowano metodę Delphi do priorytetyzacji kryteriów dotyczących potencjalnej technologii łagodzenia zmian klimatycznych w sektorze metalurgicznym w Wietnamie. Proces konsultacji został przeprowadzony z 10 ekspertami w zaledwie dwóch cyklach, aby osiągnąć wartość Kendalla (W) powyżej 0,5. Następnie 11 z 21 kryteriów zostało wybranych do analizy decyzji wielokryterialnej (MCDA) w ustalaniu priorytetów opcji łagodzenia w produkcji żelaza i stali, ołowiu, cynku, cyny i aluminium. Opcje łagodzenia z najwyższymi wynikami zostaną zaproponowane jako cel łagodzenia dla sektora metalurgicznego, który mógłby stanowić wkład dla NDC sektora przemysłowego. Wybrane kryteria obejmują 01 wskaźnik redukcji emisji (GPT1), 01 wskaźnik wpływu na środowisko (MT1), 01 wskaźniki wpływu społecznego (XH3), 02 wskaźniki skutków gospodarczych (KT1, KT2), 02 wskaźniki wpływu na zrównoważony rozwój (PTBV1 , PTBV2) i 04 wskaźników w MRV (MRV1, MRV2, MRV3, MRV4).
Źródło:
Inżynieria Mineralna; 2020, 1, 2; 247-254
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Impact of Equity Capital on the Bank’s Profitability: Evidence From Vietnam’s Banking System
Autorzy:
Thanh Xuan, Ngo
Phương Linh, Bui
Minh Huong, Le
Powiązania:
https://bibliotekanauki.pl/articles/2053923.pdf
Data publikacji:
2021-12-20
Wydawca:
Uniwersytet Warszawski. Wydawnictwo Naukowe Wydziału Zarządzania
Tematy:
bank equity capital
bank profitability
commercial banks
Opis:
From 2008 to 2019, this research examines the effect of equity capital on the profitability of 24 Vietnamese commercial banks. The research findings indicate that, when ROAA and ROAE are used to measure the bank’s profit, the equity capital ratio (CAP) has a statistically significant positive effect on the ROAA while having a negative effect on the ROAE. Between 2013 and 2019, the CAP variable has a positive effect on the ROAA and ROAE, indicating that banks with a larger equity capital ratio achieved higher profitability. Furthermore, the deposits-to-assets ratio (DTA) and loan-loss reserves ratio (LLR) both have a negative effect on both proxies for bank profitability, although bank size (SIZE) has a negligible effect on bank profits in the majority of circumstances. Additionally, the rate of GDP growth and inflation (INF) have a beneficial effect on the bank’s profitability. The study’s objective is to present some critical policy implications for bank executives about the importance of adequate equity capital for the bank’s sustainability development.
Źródło:
Journal of Banking and Financial Economics; 2021, 2(16); 56-71
2353-6845
Pojawia się w:
Journal of Banking and Financial Economics
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:
Water Lettuce (Pistia stratiotes L.) as a Potential Material for Biogas Production
Autorzy:
Cong, Nguyen Van
Thanh, Tran Van
Kha, Le Thi Mong
Hoang, Nguyen Xuan
Powiązania:
https://bibliotekanauki.pl/articles/2105278.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
water lettuce
anaerobic digestion
renewable energy
Opis:
This study evaluated the biogas production potential of water lettuce (Pistia stratiotes L.) by batch anaerobic digestion under in-vitro conditions. Twenty-one litre-plastic jars were used to conduct 4 replications over 75 days. The results showed that solution temperature, pH and Eh were suitable for biogas production. More than 50% of the obtained CH4 was formed within 17–42 days after incubation. The maximum daily CH4 production was 0.052 L/gVS, whilst the daily H2S concentration was low, with a maximum value of 28 ppm within 14–21 d after incubation. Moreover, the peak of daily biogas production was seen at day 16 with production of 0.12 L/gVS. The results highlight that water lettuce biomass can be potentially used to produce high quality biogas in anaerobic incubation.
Źródło:
Journal of Ecological Engineering; 2022, 23, 6; 182--188
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of ownership concentration on the innovation of small and medium-sized enterprises
Wpływ koncentracji własności na innowacyjność małych i średnich przedsiębiorstw
Autorzy:
Oanh, Dao Le Kieu
Nguyen, Hong Thu
Linh, Nguyen Tran Xuan
Nhan, Do Thi Thanh
Powiązania:
https://bibliotekanauki.pl/articles/27315295.pdf
Data publikacji:
2022
Wydawca:
Politechnika Częstochowska
Tematy:
ownership concentration
innovation
SMEs
FDI
Bayes
koncentracja własności
innowacje
MŚP
BIZ
Opis:
The study was conducted to assess the impact of ownership concentration on the innovation of Small and Medium-sized Enterprises (SMEs) in Vietnam. Furthermore, innovation is seen as an important element in creating competitiveness to achieve long-term development for a company. This topic has been reported in many previous pieces of research where innovation is often measured through the number of patents. However, this study measures the innovation of SMEs through whether these businesses introduce products/services or introduce a new production process or new technology in 3 years. By Logit Bayes regression method, the research results show that ownership concentration harms the innovation of SMEs in Vietnam. The authors explain this result through channels like "access to capital" and the "Risk aversion" channels.
Badanie przeprowadzono w celu oceny wpływu koncentracji własności na innowacyjność małych i średnich przedsiębiorstw (MŚP) w Wietnamie. Ponadto innowacyjność postrzegana jest jako ważny element tworzenia konkurencyjności w celu osiągnięcia długoterminowego rozwoju firmy. Ten temat został poruszony w wielu poprzednich badaniach, w których innowacyjność jest często mierzona liczbą patentów. Jednak badanie to mierzy innowacyjność MŚP poprzez to, czy te firmy wprowadzają produkty/usługi lub wprowadzają nowy proces produkcyjny lub nową technologię w ciągu 3 lat. Wyniki badań metodą regresji Logit Bayes pokazują, że koncentracja własności szkodzi innowacyjności MŚP w Wietnamie. Autorzy wyjaśniają ten wynik kanałami, takimi jak „dostęp do kapitału” i „niechęć do ryzyka”.
Źródło:
Polish Journal of Management Studies; 2022, 25, 1; 312--326
2081-7452
Pojawia się w:
Polish Journal of Management Studies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Genotype TNF-α(-308) and Silicosis on Factory Workers in Vietnam in 2020
Autorzy:
Nguyen, Viet
Nguyen, Thi Thu Huyen
Dao, Xuan Dat
Vu, Xuan Quy
Pham, Thi Quan
Le, Thi Kim Chung
Tran, Huy Thinh
Le, Thi Huong
Nguyen, Ngoc Anh
Nguyen, Viet Nhung
Nguyen, Ngoc Hong
Luong, Mai Anh
Le, Thi Thanh Xuan
Powiązania:
https://bibliotekanauki.pl/articles/2020235.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
silicosis
genotype
TNF-α
Vietnam
Wietnam
genotyp
Opis:
The studFigy aims to determine the TNF-α single-nucleotide polymorphism TNF-α (-308) and assess the association of TNF-a(-308) SNP with the risk of silicosis among workers directly exposed to silica dust in Vietnam. A study was undertaken among 78 cases with silicosis and 103 controls without silicosis in Vietnam. Blood samples were collected for genomic DNA extraction from each subject. The phenotyping of TNF-α(-308) was performed using polymerase chain reaction‐based restriction fragment length polymorphism (PCR‐RFLP) and dye termination sequencing. Results: The average exposure time of the case group was slightly higher than that of the control group (12.46 ± 6.732 years vs. 12.09 ± 7.854 years). The majority of genotypes in both silicosis and non-silicosis was GG. When analyzing the concentration of TNF-α in the study participants' blood, it is shown that the average concentration of TNFα in the case group was higher than that in the control group. The genotype AG in the case group was 1.368 times higher than that in the control group. The percentage of all A alleles in the case group with silicosis was 1.342 times higher than the control group without the disease, similar to previous studies. Conclusion: The majority of genotypes in both groups was GG. The average concentration of TNF-α in blood, genotype AG, and the percentage of all A alleles in the case group was higher than that in the control group.
Źródło:
Inżynieria Mineralna; 2021, 2; 459--466
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effectiveness of a Mobile Application-Based Intervention to Improve Knowledge and Practice Regarding Silicosis Among High-Risk Workers of Dust Exposure in a Northern Province of Vietnam
Autorzy:
Nguyen, Thi Thu Huyen
Ta, Thi Kim Nhung
Pham, Thi Quan
Nguyen, Thanh Thao
Nguyen, Ngoc Anh
Nguyen, Thi Lien Huong
Le, Thi Huong
Luong, Mai Anh
Le, Thi Thanh Xuan
Powiązania:
https://bibliotekanauki.pl/articles/27323251.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
knowledge
practice
workers
silicosis
mobile application
effectiveness
praca
aplikacja mobilna
Wietnam
Opis:
Objectives: to analyze changes in knowledge and practices regarding silicosis in groups of workers at high risk of silicosis before - after an intervention. Methods: The study was conducted from 2018 to 2019 based on structured questions related to knowledge and practices of silicosis of workers directly exposed to silica dust in a Northern province of Vietnam. The mobile app-based intervention was applied to steel workers, then compared with ironworkers in improvements in silicosis knowledge and practices. Results: Significant changes in the intervention group related to workers' knowledge about the signs suggestive of silicosis, disease consequences, measures to reduce the risk of silicosis, and participation in annual occupational disease examinations were reported. Conclusion: Mobile applicationbased interventions could improve silicosis knowledge and practice among workers at high risk of exposure to silica dust.
Źródło:
Inżynieria Mineralna; 2023, 2; 295--302
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Response surface methodology for optimization studies of hydro-distillation of essential oil from pixie mandarin (Citrus reticulata Blanco) peels
Autorzy:
Tan, Phat Dao
Ngo, Thi Cam Quyen
Tran, Thi Yen Nhi
Chi, Cuong Nguyen
Trung, Thanh Nguyen
Xuan, Tien Le
Powiązania:
https://bibliotekanauki.pl/articles/2081508.pdf
Data publikacji:
2021
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
Hydro-distillation
pixie mandarin oil (Citrus reticulata Blanco)
RSM
GC-MS
Opis:
Essential oil extraction technique from mandarin pixie peels by hydro-distillation is optimized by respon-se surface methodology (RSM). Mathematical techniques were used in experimental design to evaluate the impacts of factors that affect the extraction process and improve the yield of the extraction process. A central mixed design based on infl uencing variables such as water ratio (3–5 mL/g), temperature (110–130° C) and extraction time (90–150 min) was adopted with essential oil yield as the target func-tion. Correlation analysis of the mathematical regression model showed that the quadratic polynomial model can be used to optimize hydro-distillation of pixie mandarin oil. The results showed that under the optimum extraction conditions, the highest quantity of essential oils was achieved (7.28 mL/100 g materials). In terms of statistical analysis, the signifi cance levels (p-value <0.05) of the model showed that the experimental results had a good impact between factors. The coeffi cient of determination indicating the match between the experimental value and the predicted value of the model was high (R2>0.9). The chemical composition of the essential oil was analyzed by Gas Chromatography-Mass Spectrometry, revealing the dominance of limonene content (97.667%), which implies that the essential oil of pixie mandarin could be an alternative source of limonene.
Źródło:
Polish Journal of Chemical Technology; 2021, 23, 4; 26-34
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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