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Tytuł:
Effect of two-stage stirred pulp-mixing on coal flotation
Autorzy:
Gui, X.
Wang, Y.
Zhang, H.
Li, S.
Powiązania:
https://bibliotekanauki.pl/articles/110764.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mixing
stirred
two stage
fine coal
flotation
Opis:
Stirred pulp-mixing is performed before coal flotation. In this study, a two-stage stirred pulpmixing tank was designed based on the single-stirred process to intensify the mixing effect of pulp and flotation reagents. A tank has a pitched-impeller opening-type turbine. Stirred pulp-mixing and flotation experiments were conducted on a sample of anthracite fine coal (-0.5mm) from the Xuehu Coal Preparation Plant in Henan Province, China. The results of the two-stage stirred pulp-mixing were compared with those of a single-stage stirred pulp-mixing in terms of flotation performance. Compared with the single-stage stirred pulp-mixing, two mixing areas and double-layer impeller were able to strengthen the energy input to the stirred system, thereby improving the mixing efficiency of flotation reagents and coal particles in the pulp. The two-stage stirred pulp-mixing significantly increased the flotation feed rate of the cyclone-static micro-bubble flotation column and concentrate yield, enhanced the combustible matter recovery effect of coarse particles at a suitable flotation feed rate, and ensured the recovery effect of fine particles at high flotation feed rate.
Źródło:
Physicochemical Problems of Mineral Processing; 2014, 50, 1; 299-310
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fuzzy-PID control method for two-stage vibration isolation system
Połączenie sterowania rozmytego z regulatorem PID w dwustopniowym układzie wibroizolacji
Autorzy:
Zhao, C-S.
Zhu, S-J.
He, Q-W.
Powiązania:
https://bibliotekanauki.pl/articles/280755.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
two-stage vibration isolation system
fuzzy-PID control
simulation
Opis:
The arithmetic of PID control is simple and the stability of it is good. However, the dynamic characteristics of PID control are poor. The fuzzy logic control method is flexible and adaptive. It does not rely on a mathematical model of the system and can deal with the nonlinearity of parameters and uncertain problems. However, the stability of fuzzy logic control is poor. In this paper, fuzzy logic control combined with PID control is applied to a two-stage vibration isolation system to improve the vibration isolation effectiveness. Simulation results show that the method is effective.
Arytmetyka regulatora PID jest prosta, a jego stabilność dobra. Jednakże charakterystyki dynamiczne PID już tak korzystne nie są. Z drugiej strony, metody sterowania oparte na logice rozmytej są elastyczne i cechuje je duża zdolność adaptacyjna. Nie polegają one na ścisłym modelu matematycznym danego układu i dobrze sobie radzą z nieliniowościami parametrów i słabo zdefiniowanymi zagadnieniami. Niestety stabilność sterowania z logiką rozmytą jest niedostateczna. W pracy zaprezentowano rodzaj kombinacji metody logiki rozmytej z regulatorem PID zastosowanej do dwustopniowego układu izolacji drgań. Przeprowadzone symulacje pokazały efektywność takiego podejścia.
Źródło:
Journal of Theoretical and Applied Mechanics; 2007, 45, 1; 171-177
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation of work of an engine working with combustion initiation from ignition dose of fuel
Autorzy:
Sendyka, B.
Mitianiec, W.
Noga, M.
Powiązania:
https://bibliotekanauki.pl/articles/245989.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
modelling
simulation
combustion engine
HCCI
two stage injection system
Opis:
The paper presents analysis of fuelling and of the course of combustion process for a two-cycle engine. The main idea of the engine according to patent solution of Prof. B. Sendyka consists in the fact that engine work begins from spark ignition, whereas, at higher load and higher temperature in the cooling system there occurs switching off spark ignition and transition to ignition from an ignition dose injected directly into the combustion chamber. Such an engine possesses two injection systems: one system of multi-point injection which forms homogenous mixture, whereas, the other system of direct injection is used for ignition dose injection only. After injection of the ignition dose of a very small mass combustion is initiated on the basis of formation of auto-ignition centres so as it takes place during knock combustion. Auto-ignition centres initiate combustion of the basic charge. Simulation was carried out in order to perform analysis occurring phenomena of fuel feeding and combustion. Works on it started from elaboration of a computational grid of the engine and subsequently analysis of indicated diagrams of engine work with injection of ignition dose was performed. Analysis was also performed of temperature traces and of traces of charge mass change in the cylinder as well as of participation of the mass of basic fuel dose in the cylinder in function of the crank angle. Moreover visualization of effects of the process of mixture formation and combustion was performed and presented in form of illustrations of charge temperature distribution, fraction of fuel ignition and basic dose vapours in cross-sections of the combustion chamber.
Źródło:
Journal of KONES; 2011, 18, 3; 395-403
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Maximization of Estimation Accuracy in Multiparameter Two Stage Sampling
O maksymalizacji dokładności estymacji w wieloparametrowym losowaniu dwustopniowym
Autorzy:
Skibicki, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/904926.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
two stage sampling
sample allocation
covariance matrix
spectral radius
Opis:
In the paper the problem of sample allocation for both stages in such a way, that the accuracy of an estimation of the means of many variables is maximal and the survey cost is restricted is considered. As the measure of accuracy, value of the spectral radius of covariance matrix of means estimators vector is taken. It was proved that the spectral radius is a convex function of sample sizes. That allows effective solving the problem using known methods adapted to this issue.
W pracy rozważano zadanie ustalenia liczebności prób losowanych na obydwu stopniach losowania tak, aby dokładność estymacji średnich wielu cech populacji była maksymalna przy kosztach obserwacji próby nieprzekraczających zadanego poziomu. Za miarę dokładności estymacji przyjęto wartość promienia spektralnego macierzy kowariancji wektora estymatorów wartości średnich cech. Wykazano, że promień spektralny tej macierzy dla przekształconego zadania jego minimalizacji jest wypukłą funkcją odpowiedniego wektora. Pozwala to na efektywne poszukiwanie optymalnego rozwiązania przy użyciu znanych metod adaptowanych do tego problemu.
Źródło:
Acta Universitatis Lodziensis. Folia Oeconomica; 2004, 175
0208-6018
2353-7663
Pojawia się w:
Acta Universitatis Lodziensis. Folia Oeconomica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of energy consumption of crushing processes – comparison of one-stage and two-stage processes
Autorzy:
Ciężkowski, P.
Maciejewski, J.
Bąk, S.
Powiązania:
https://bibliotekanauki.pl/articles/178852.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rock crushing
jaw crusher
crushing efficiency
two stage crushing process
Opis:
This paper presents experimental comparison of two machine crushing technologies: one-stage and two-stage. The study was carried on a model double-toggle jaw crusher which allows crushing forces, energy and toggle displacement to be measured. The main aim of the work was to determine the energy consumption of crushing process assuming a given level of fragmentation. Studies were performed on three rocks: granite “Strzegom”, limestone “Morawica” and sandstone “Mucharz”. The material tested had a cubic shape and average dimension of 90 mm. One-stage crushing was carried out for outlet slot er = 11 mm, and two-stage crushing for er = 24 mm and 11 mm. In the tests special design of variable profile moving jaw was used and fixed jaw was flat. The analysis of the results shows that taking into account energy consumption, it is better to use two-stage crushing process. For given materials energy consumption in the two-stage crushing process was reduced by 30%.
Źródło:
Studia Geotechnica et Mechanica; 2017, 39, 2; 17-24
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determinants of agricultural loan decision making process for rice (Oryza sativa) farmers in Abuja, Nigeria. Applications of Heckman two-stage model and factor analysis
Autorzy:
Alabi, Olugbenga Omotayo
Oladele, Ayoola Olugbenga
Usman, Mohammed Bello
Powiązania:
https://bibliotekanauki.pl/articles/1886576.pdf
Data publikacji:
2021-04-02
Wydawca:
Uniwersytet Przyrodniczy w Poznaniu. Wydawnictwo Uczelniane
Tematy:
agricultural loan decision
Heckman two-stage model
rice farmers
Nigeria
Opis:
This study focuses on determinants of the agricultural loan decision-making process of rice (Oryza sativa) farmers in Abuja, Nigeria, using the Heckman two-stage model and factor analysis. This study was designed specifically to achieve the following objectives: determine the socio-economic profiles or characteristics of rice farmers, analyze the costs and returns of rice production, evaluate factors influencing rice farmers’ decision to obtain an agricultural loan, evaluate socio-economic factors influencing the amount of the agricultural loan, and determine the constraints or problems facing rice farmers. A multi-stage sampling design was employed. A total sample of one hundred (100) rice farmers was included, and primary data were utilized. Data were obtained through the use of a well-structured and well-designed questionnaire. Statistical and econometric tools used in analyzing data included descriptive statistics, gross margin analysis, financial analysis, the Heckman two-stage model, and principal component analysis. The results show that 63% of rice farmers were between the age of 31–50 years. The mean age was 41.90 years. About 65% of rice farmers were male, and 54% of them were married. Also, 93% of rice farmers had formal education and were literate. The household sizes were large, with an average of six persons per household. An average of 71,550 nairas was the loan amount granted to rice farmers by financial institutions. The average farm size amounted to 1.49 hectares. Factors influencing the decision of rice farmers to obtain agricultural loan included age (P < 0.01), marital status (P < 0.05), household size (P < 0.10), educational level (P < 0.05), farm size (P < 0.05), farm and non-farm income (P < 0.10), farm experience (P < 0.05), collateral property (P < 0.05), extension services (P < 0.10), and awareness of loan or credit facilities (P < 0.05). Rice production was profitable with a net farm income of 744,300 nairas. The gross margin ratio of 0.95 means that 95 kobos covered profits, taxes, expenses, interest, and depreciation for every naira invested in rice production activities. Socio-economic factors statistically and significantly influencing the amount of agricultural loan obtained by rice farmers included (P < 0.05) sex (P < 0.01), household size (P < 0.05) and educational level (P < 0.01). The constraints facing rice farmers in obtaining the agricultural loan and production activities included lack of collateral property, lack of fertilizer input, poor-quality feeder roads, lack of credit facilities, inadequate labor input, and complicated and costly administrative procedures to obtain a loan. It is recommended that agricultural loans be made available to rice farmers in sufficient amounts and at low-interest rates. Also, farm inputs, fertilizer inputs, improved seeds, and chemicals should be made available to rice farmers.
Źródło:
Journal of Agribusiness and Rural Development; 2021, 59, 1; 29-38
1899-5241
Pojawia się w:
Journal of Agribusiness and Rural Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A two-stage stochastic programming approach for production planning system with seasonal demand
Autorzy:
Mahmoud, Asmaa A.
Aly, Mohamed F.
Mohib, Ahmed M.
Afefy, Islam H.
Powiązania:
https://bibliotekanauki.pl/articles/952860.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
process manufacturing system
two-stage stochastic programming
sampling average approximation
Opis:
Seasonality is a function of a time series in which the data experiences regular and predictable changes that repeat each calendar year. Two-stage stochastic programming model for real industrial systems at the case of a seasonal demand is presented. Sampling average approximation (SAA) method was applied to solve a stochastic model which gave a productive structure for distinguishing and statistically testing a different production plan. Lingo tool is developed to obtain the optimal solution for the proposed model which is validated by Math works Matlab. The actual data of the industrial system; from the General Manufacturing Company, was applied to examine the proposed model. Seasonal future demand is then estimated using the multiplicative seasonal method, the effect of seasonality was presented and discussed. One might say that the proposed model is viewed as a moderately accurate tool for industrial systems in case of seasonal demand. The current research may be considered a significant tool in case of seasonal demand. To illustrate the applicability of the proposed model a numerical example is solved using the proposed technique. ANOVA analysis is applied using MINITAB 17 statistical software to validate the obtained results.
Źródło:
Management and Production Engineering Review; 2020, 11, 1; 31--42
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A compositional approach to two-stage Data Envelopment Analysis in intuitionistic fuzzy environment
Autorzy:
Javaherian, Nafiseh
Hamzehee, Ali
Tooranloo, Hossein Sayyadi
Powiązania:
https://bibliotekanauki.pl/articles/2099430.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
data envelopment analysis
intuitionistic fuzzy
two-stage DEA
triangular numbers
Opis:
Classical methods of data envelopment analysis operate by measuring the efficiency of decision- -making units (DMUs) compared to similar units, without taking their internal structure into account. However, some DMUs consist of two stages, with the first stage producing an intermediate product, which is then consumed in the second stage to produce the final output. The efficiency of this type of DMU is often measured using two-stage network data envelopment analysis. In real world, most data are vague. Therefore, the inputs and outputs of systems with vagueness data create uncertainty challenges for DMUs. As a result, when uncertainty appears, intuitionistic fuzzy sets can show more information than classical fuzzy sets. This paper presents a model of two-stage Network Data Envelopment Analysis based on intuitionistic fuzzy data, which measures the efficiency of the first and second stages of each DMU, and the overall efficiency measures based on the stage efficiencies.
Źródło:
Operations Research and Decisions; 2021, 31, 1; 21--39
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of government policies on Sustainable Petroleum Supply Chain (SPSC): A case study – Part II (The State of Nebraska)
Autorzy:
Ghahremanlou, Davoud
Kubiak, Wieslaw
Powiązania:
https://bibliotekanauki.pl/articles/1818474.pdf
Data publikacji:
2020
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
sustainable petroleum supply chain
two-stage stochastic programming
government policies
Opis:
The accompanying part I (Ghahremanlou and Kubiak 2020) developed the Lean Model (LM), a two-stage stochastic programming model which incorporates Renewable Fuel Standard 2 (RFS2), Tax Credits, Tariffs, and Blend Wall (BW), to study the policy impact on the Sustainable Petroleum Supply Chain (SPSC) using cellulosic ethanol. The model enables us to study the impact by running computational experiments more efficiently and consequently by arriving at robust managerial insights much faster. In this paper, we present a case study of the policy impact on the SPSC in the State of Nebraska using the model. The case study uses available real-life data. The study shows that increasing RFS2 does not impact the amount of ethanol blended with gasoline but it might lead to bankruptcy of the refineries. We recommend that the government consider increasing the BW because of its positive economic, environmental and social impacts. For the same reason, we recommend that the tax credit for blending the US produced ethanol with gasoline be at least 0:189 $/gal and the tariff for imported ethanol be at least 1:501 $/gal. These also make the State independent from foreign ethanol thereby enhancing its energy security. Finally, the change in policy impacts the SPSC itself, most importantly it influences the strategic decisions, however setting up a bio-refinery at York county and a blending site at Douglas county emerge as the most robust location decisions against the policy change in the study.
Źródło:
Decision Making in Manufacturing and Services; 2020, 14, 1; 57--80
1896-8325
2300-7087
Pojawia się w:
Decision Making in Manufacturing and Services
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of government policies on Sustainable Petroleum Supply Chain (SPSC): A case study – Part I (Models)
Autorzy:
Ghahremanlou, Davoud
Kubiak, Wieslaw
Powiązania:
https://bibliotekanauki.pl/articles/1818475.pdf
Data publikacji:
2020
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
sustainable petroleum supply chain
two-stage stochastic programming
government policies
Opis:
Environmental concerns and energy security have led governments to establish legislations to convert Conventional Petroleum Supply Chain (CPSC) to Sustainable Petroleum Supply Chain (SPSC). The United States (US), one of the biggest oil consumers in the world, has created regulations to manage ethanol production and consumption for the last half century. Though these regulations have created new opportunities, they have also added new burdens to the obligated parties. It is thus key for the government, the obligated parties, and related businesses to study the impact of the policies on the SPSC. We develop a two-stage stochastic programming model, General Model (GM), which incorporates Renewable Fuel Standard 2 (RFS2), Tax Credits, Tariffs, and Blend Wall (BW) to study the policy impact on the SPSC using cellulosic ethanol. The model, as any other general model available in the literature, makes it highly impractical to study the policy impact due to the model’s computational complexity. We use the GM to derive a Lean Model (LM) to study the impact by running computational experiments more efficiently and consequently by arriving at robust managerial insights much faster. We present a case study of the policy impact on the SPSC in the State of Nebraska using the LM in the accompanying part II (Ghahremanlou and Kubiak 2020).
Źródło:
Decision Making in Manufacturing and Services; 2020, 14, 1; 23--55
1896-8325
2300-7087
Pojawia się w:
Decision Making in Manufacturing and Services
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 65

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