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Tytuł:
Study on condition prediction and influencing factors of manganese carbonate recovery by high gradient pulse magnetic separation
Autorzy:
Wang, Zhenggang
Nie, Guanghua
Tang, Yun
Piao, Haishan
Chen, Jian
Powiązania:
https://bibliotekanauki.pl/articles/24085829.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mineral particles
impulse
volume susceptibility
magnetic field strength
DLVO theory
Opis:
Manganese carbonate ore belongs to weakly magnetic minerals, and its co-associated minerals are mainly non-magnetic minerals, which can be separated from gangue minerals at high magnetic field intensity. However, manganese grade and recovery of magnetic separation concentrate of manganese carbonate ore are low in actual production. Therefore, the influences of manganese carbonate particle size, magnetic field intensity, volume susceptibility, pulse stroke, pH, and other factors were studied. The optimal test conditions for manganese carbonate ore recovery by high-gradient magnetic separation were predicted through the calculation results. The results show that the particle radius of manganese carbonate is 0.020 mm, the pulse impulse time is 200 r/min, and the magnetic field intensity is 0.9 T. The optimum condition test was carried out with Qianbei manganese carbonate ore as the material. The test results show that the optimum conditions are the particle radius of 0.074-0.019 mm, pulse impulse time of 200 r/min, and magnetic field intensity of 1.2 T. The reason for the deviation is that the actual ore has a fine distribution particle size, many associative bodies, complex composition, and serious agglomeration, resulting in variable particle volume susceptibility. The capture yield increases with the increase of magnetic field intensity and volume susceptibility but decreases with the increase of pulse. The lower the surface potential of manganese carbonate, the higher the recovery of manganese carbonate. The grade of manganese concentrate was 19.06% and the recovery was 76.85%. Mixed manganese concentrate with a grade of 18.04% and recovery of 87.14% was obtained by adding drugs and changing the grinding method.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 3; art. no. 168668
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Factors influencing the mental health status of support nurses and their workload during the COVID-19 epidemic
Autorzy:
Dai, Zhen-Juan
Xu, Shen-Ting
Xue, Fang-Ying
Zhou, Jian-Ying
Chen, Jian-Qin
Wang, Xue-Min
Powiązania:
https://bibliotekanauki.pl/articles/23369109.pdf
Data publikacji:
2023-12-15
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
COVID-19
mental health
epidemic prevention and control
general mental health questionnaire
NASA-TLX
support nurse
Opis:
Objectives The authors used the National Aeronautics and Space Administration Task Load Index (NASA-TLX) and general health questionnaire to analyze the factors influencing the mental health status and the workload of support nurses during the COVID-19 epidemic. Material and Methods The authors conducted a cross-sectional survey of 349 support nurses in April–October 2022. Using QuestionStar, a powerful online survey tool, the authors administered surveys to the participants, collected data on the mental health status and workload of support nurses, and analyzed the influencing factors based on the collected data. Results A total of 316 questionnaires were successfully collected, with an effective rate of 98.75%. The proportion of support nurses with mental health problems was 25% and the value of the NASA-TLX questionnaire was: M±SD 68.91±7.28 pts. Multi-factor analysis revealed that the number of children, family support, and nursing support location were the influencing factors of mental health status, while the multivariate analysis revealed that the presence of symptoms, nursing support location, support work type, and total 12-item General Health Questionnaire (GHQ-12) score were the influencing factors of the workload of support nurses. Conclusions Compared to their counterparts in the plains, nurses working in isolated plateau regions who were caring for children and lacked family support, were more likely to have mental health issues. There was a positive correlation between the changes in GHQ-12 and NASA-TLX scores of the study participants. Compared to their counterparts in the plains and the tropical regions, nurses working in plateau regions had a heavier workload. As part of the follow-up measures to prevent and treat patients impacted by the COVID-19 epidemic, it is important to improve the mental health evaluation, consultation, and treatment of the support nurses to guarantee the high quality of the first-line support work.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2023, 36, 6; 761-772
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal Structure and Thermal Behaviour of Imidazolium 2,4,5-Trinitroimidazolate
Autorzy:
Jian, Chen
Pengbao, Lian
Lizhen, Chen
Jianlong, Wang
Jun, Chen
Powiązania:
https://bibliotekanauki.pl/articles/357998.pdf
Data publikacji:
2019
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
imidazolium 2,4,5-trinitroimidazolate
crystal structure
thermal decomposition
TG-DSC
model-free methods
Opis:
In this work, imidazolium 2,4,5-trinitroimidazolate was obtained from 2,4,5-tri-iodoimidazole in a yield of 48%. Single-crystal X-ray diffraction analysis showed that this compound belongs to the triclinic crystal system with space group P-1. Thermogravimetric-differential scanning calorimetry (TG-DSC) was performed under a nitrogen atmosphere at heating rates of 5, 10, 15 and 20 °C·min−1. Compound 3 clearly exhibits an exothermic decomposition. The activation energy (E) and pre-exponential factor (lnA) calculated by the Kissinger method were 113.67 kJ·mol−1 and 25.30 s−1, respectively. The E values obtained by the FWO and KAS methods changed slightly from 103.33 to 113.69 kJ·mol−1 and from 101.52 to 111.97 kJ·mol−1, respectively, which makes us believe that its thermal decomposition can be described using only one reaction model. The Šatava-Šesták method and the compensation effect were used to study the thermal decomposition mechanism of imidazolium 2,4,5-trinitroimidazolate. [Formula] is regarded as the most appropriate thermal decomposition kinetic equation. The impact sensitivity, friction sensitivity, detonation velocity and explosion pressure of imidazolium 2,4,5-trinitroimidazolate were 43 cm, 46%, 7056.9 m·s−1 and 1.9703 · 1010 Pa (ρ = 1.538 g·cm−3), respectively. Imidazolium 2,4,5-trinitroimidazolate is incompatible with RDX, HMX, TKX-50 and CL-20.
Źródło:
Central European Journal of Energetic Materials; 2019, 16, 4; 547-563
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pollution, Happiness and Willingness to Pay Taxes:The Value Effect of Public Environmental Policies
Zanieczyszczenie, szczęście i chęć płacenia podatków: efekt wartości w ramach publicznych polityk ekologicznych
Autorzy:
Liu, Nannan
Liu, Rong
Huang, Jian
Chen, Lingshuang
Powiązania:
https://bibliotekanauki.pl/articles/371270.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Komitet Człowiek i Środowisko PAN
Tematy:
environmental pollution
sense of happiness
willingness to pay taxes
public policy
zanieczyszczenia środowiska
poczucie szczęścia
podatki oparte na gotowości do zapłaty
polityka publiczna
Opis:
As China’s economic development pattern is marked by an excessive consumption of fossil fuels, environmental pollution problems in China are getting increasingly serious and threatening residents’ fundamental demands for a high quality of life. It has become a handicap to sustainable economic development and social well-being. In this paper, the happiness index method were used, and models depicting the relationship between residents’ sense of happiness and environmental pollution factors and between the willingness to pay taxes and environmental pollution factors have been established. The results show that environmental pollution, especially air pollution, significantly affects the residents’ sense of happiness. To improve residential environment quality and reduce pollution, residents are willing to pay the relevant taxes. If pollution control is considered a public policy, there exists a substantive weight of government between residents’ income and environmental quality. This will influence the choice of environmental public policy.
Rozwój ekonomiczny Chin powiązany jest z nadmiernym zużywaniem paliw kopalnych, a zanieczyszczenia środowiska osiągają poziom, który stanowi zagrożenie dla oczekiwanego przez obywateli wysokiego poziomu życia. Stało się to przeszkodą dla zrównoważonego rozwoju gospodarczego i dobrobytu społecznego. W niniejszym opracowaniu wykorzystano metodę wskaźnika szczęścia. Opracowano modele obrazujące związek między poczuciem szczęścia mieszkańców a zanieczyszczeniami środowiska oraz między chęcią płacenia podatków a czynnikami zanieczyszczenia środowiska. Wyniki pokazują, że zanieczyszczenie środowiska, w szczególności zanieczyszczenie powietrza, znacząco wpływa na poczucie szczęścia mieszkańców. Aby poprawić jakość środowiska mieszkańców i zmniejszyć zanieczyszczenie, obywatele są skłonni zapłacić odpowiednie podatki. Jeżeli kontrola zanieczyszczeń jest uważana za politykę publiczną, rząd odgrywa istotną rolę w kształtowaniu relacji między dochodami mieszkańców a jakością środowiska. Wpłynie to bowiem na wybór polityki publicznej dotyczącej środowiska.
Źródło:
Problemy Ekorozwoju; 2018, 13, 1; 75-86
1895-6912
Pojawia się w:
Problemy Ekorozwoju
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A modified Fourier-Ritz method for free vibration of rectangular plates with elastic constrains
Autorzy:
Wu, Tao
Chen, Zhao Bo
Qu, Jian Jun
Powiązania:
https://bibliotekanauki.pl/articles/2086961.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
modified Fourier-Ritz method
rectangular plate
free vibration
boundary conditions
Opis:
In this paper, a modified Fourier-Ritz method is used to study free vibration of a rectangular plate with a set of simply supported opposite sides and another set of arbitrary elastic constraints. The influence of different elastic constraint stiffness values on the modal response of the rectangular plate is also analyzed. In order to avoid that the displacement function of the rectangular plate calculated by the traditional method and its derivative may be discontinuous or non-derivable at the boundary, the displacement function is expressed in the form of the sum of standard cosine series and a periodic polynomial function. Compared with the sine series expansion, the convergence of the result is enhanced. Several sets of numerical examples with different boundary conditions are given in the article, the data shows that the results calculated by this method have good accuracy and fast convergence. In addition, this paper also analyzes the boundary conditions and discusses the influence of different spring stiffness values on the setting of boundary conditions. The results can be applied to the setting of general boundary conditions and the study of vibration control of rectangular plates.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 1; 77--89
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Urinary concentrations and determinants of pyrethroid metabolites in pregnant women from non-rural areas of Yunnan, China
Autorzy:
Xu, Q.
Song, X.
Li, Y.
Jian, X.
Chen, S.
Chen, Y.
Powiązania:
https://bibliotekanauki.pl/articles/28762713.pdf
Data publikacji:
2021
Wydawca:
Instytut Medycyny Wsi
Źródło:
Annals of Agricultural and Environmental Medicine; 2021, 28, 4; 627-632
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on low frequency ripple suppression technology of inverter based on model prediction
Autorzy:
Liu, Haiyang
Chen, Yiwen
Luo, Sixu
Jiang, Jiahui
Jian, Haojun
Powiązania:
https://bibliotekanauki.pl/articles/24202730.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
boost type
low frequency ripple suppression
model predictive control
single stage inverter
Opis:
The low frequency ripple of the input side current of the single-phase inverter will reduce the efficiency of the power generation system and affect the overall performance of the system. Aiming at this problem, this paper proposes a two-modal modulation method and its MPC multi-loop composite control strategy on the circuit topology of a single-stage boost inverter with a buffer unit. The control strategy achieves the balance of active power on both sides of AC and DC by controlling the stable average value of the buffer capacitor voltage, and provides a current reference for inductance current of the DC input side. At the same time, the MPC controller uses the minimum inductor current error as the cost function to control inductor current to track its reference to achieve low frequency ripple suppression of the input current. In principle, it is expounded that the inverter using the proposed control strategy has better low frequency ripple suppression effect than the multi-loop PI control strategy, and the conclusion is proved by the simulation data. Finally, an experimental device of a single-stage boost inverter using MPC multi-loop composite control strategy is designed and fabricated, and the experimental results show that the proposed research scheme has good low frequency ripple suppression effect and strong adaptability to different types of loads.
Źródło:
Archives of Electrical Engineering; 2023, 72, 2; 443--460
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An early warning method for a slope based on the increment ratio of anchor cable internal force
Autorzy:
Feng, Jianhua
Chen, Jiaxin
Li, Jian
Zhang, Yu
Guo, Jianhua
Qiu, Hongyong
Powiązania:
https://bibliotekanauki.pl/articles/2203436.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
Prestressed anchor cables are active reinforcement to improve slope stability. However, the anchoring is not a permanent guarantee of stability, and the slope retains a potential risk of instability. From the perspective of the internal force of anchor cables, a new early warning method for the safety of the slope is provided, and a slope analysis model is established. With the increase in the strength reduction factor, the internal force increment curves of anchor cables under different prestresses are obtained. The point corresponding to strength reduction factors λ1 and λ2 represents a warning point. Key conclusions are drawn as follows: (1) The internal force of an anchor cable can be used to judge the stability of the slope strengthened by a prestressed anchor cable. (2) A warning index based on the internal force increment ratio of anchor cables is established. (3) The internal force increment ratio of anchor cables eliminates the influence of the initial prestress and is convenient for engineering applications.
Źródło:
Archives of Civil Engineering; 2023, 69, 1; 553--569
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of socio-economic spatial structure of urban agglomeration in China based on spatial gradient and clustering
Autorzy:
He, Li
Tao, Jian’ge
Meng, Ping
Chen, Dan
Yan, Meng
Vasa, László
Powiązania:
https://bibliotekanauki.pl/articles/19233717.pdf
Data publikacji:
2021
Wydawca:
Instytut Badań Gospodarczych
Tematy:
economic and social development
urban agglomeration
Central Plains Urban Agglomeration (CPUA)
clustering
spatial gradient
Opis:
Research background: Previous studies on the economic and social development of urban agglomerations mostly focus on a single primacy comparative analysis and efficiency evaluation. Spatial structure differentiation is an important feature of urban agglomeration. The lack of economic and social analysis on the spatial structure makes it impossible to determine the development positioning of each city in the urban agglomeration, which affects the sustainable economic development ability of these areas. Purpose of the article: The objective of the article is to analyze the spatial development law and experience of urban agglomeration, this study explores the practice of economic and population spatial structure of city areas in China. For this purpose, CPUA and its central city Zhengzhou was taken as an example, the spatial gradient structure of example was analyzed. Methods: Using economic and population data of 32 cities in this region, growth pole theory, and pole-axis theory, the economic and population spatial structure of urban agglomeration, the spatial gradient structure of central cities in urban agglomerations were analyzed with the method of cluster about radiation index. Findings & value added: (1) In the process of the formation of CPUA, the geo-graphical spatial pattern plays a decisive role in economic and social development. This is an experience from developing countries. (2) CPUA presents a gradient development pattern with Zhengzhou as the center, and economic and social development gradually radiates to the metropolitan area, the core development area, and the character development demonstration area. (3) The economic and social gradients of Zhengzhou, the central city, present the hierarchy rules and characteristics which are driven by the Beijing-Guangzhou-Railway axis and the Longhai-Railway axis. (4) The central city of Zhengzhou still presents insufficient primacy in regional development, which shows that Zhengzhou accounts for 6% of the population of the Central Plains Economic Zone and 14% of GDP, and insufficient agglomeration. Different countries at different stages of economic development have different urban agglomeration development models. The conclusions from China provide new decision-making ideas and methods for spatial structure research and development strategy analysis of urban agglomerations.
Źródło:
Oeconomia Copernicana; 2021, 12, 3; 789-819
2083-1277
Pojawia się w:
Oeconomia Copernicana
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue reliability analysis of the brake pads considering strength degradation
Autorzy:
Zhang, Nan
Jiang, Guang-Jun
Wu, Dong-Wei
Chen, Hong-Xia
Wu, Jian-Xin
Powiązania:
https://bibliotekanauki.pl/articles/1841941.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
stress-strength interference model
dynamic reliability
strength degradation
impact load
Opis:
Reliability prediction of the brake pads is indispensable to guarantee their safety. In the paper, the fatigue reliability of brake pads is analyzed by dynamic stress-strength interference (SSI) model considering strength degradation. Firstly, reliability model of the brake pads was established based on stress-strength interference model considering the influence of impact load. Then reliability of the brake pads was predicted under different impact load frequency and initial strength. Finally, the influence of random degradation strength on reliability was studied by contrast. The analysis results show that random strength degradation, impact load and initial strength have great influence on reliability prediction for the brake pads. Therefore, the reliability prediction of the brake pads fatigue strength considering strength degradation is more in line with the actual situation and the calculation accuracy is higher.
Źródło:
Eksploatacja i Niezawodność; 2020, 22, 4; 620-626
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 15

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