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Tytuł:
Polish Finishers from Danish Piglets: Uncontrolled Transformation of Pig Industry in Poland
Polskie tuczniki z duńskich prosiąt – niekontrolowana transformacja polskiego sektora trzody chlewnej
Autorzy:
Olipra, Jakub
Powiązania:
https://bibliotekanauki.pl/articles/43195744.pdf
Data publikacji:
2023-06-28
Wydawca:
Instytut Ekonomiki Rolnictwa i Gospodarki Żywnościowej - Państwowy Instytut Badawczy
Tematy:
rynki rolne
sektor trzody chlewnej
bezpieczeństwo żywnościowe
specjalizacja rynkowa
VECM
ceny
agricultural markets
pig industry
food security
market specialization
vector error correction model
prices
Opis:
Jeszcze 20 lat temu Polska była samowystarczalna w produkcji świń, będąc jednym z kluczowych graczy na europejskim rynku trzody chlewnej. Od tego czasu obserwuje się rosnącą specjalizację Polski w zakresie tuczu świń i przetwórstwa mięsa, przy jednoczesnym spadku krajowej produkcji prosiąt. W konsekwencji Polska utraciła samowystarczalność w produkcji świń i stała się silnie uzależniona od importu prosiąt, głównie z Danii. Celem niniejszego opracowania jest podsumowanie ewolucji polskiego sektora trzody chlewnej oraz określenie głównych determinant polskiego importu prosiąt z Danii. Wyniki oszacowań przy użyciu modelu VECM wskazują, że wielkość polskiego importu prosiąt z Danii może być wyjaśniona przez stopień specjalizacji Polski w zakresie tuczu świń, fazę cyklu świńskiego oraz konkurencyjność polskiej wieprzowiny. Wyniki mogą być pomocne w zrozumieniu ewolucji polskiego sektora trzody chlewnej i jego rosnącego uzależnienia od importu prosiąt.
Only 20 years ago, Poland was self-sufficient in pig production, being one of the key players in the Euro- pean pig market. Since then a growing specialization of Poland in pig finishing and meat processing has been observed, while the domestic production of piglets has declined. As a consequence, Poland has lost its self-sufficiency in pig production and become strongly dependent on imports of piglets, mainly from Denmark. The aim of this paper is to summarize the evolution of the Polish pig industry and specify the main determinants of the Polish imports of Danish piglets. The results of the estimates using the vector error correction model (VECM) show that the volume of the Polish imports of piglets from Denmark may be explained by a degree of specialization of Poland in pig finishing, the phase of pig cycle, and the competitiveness of Polish pork. The results may be helpful in understanding the evolution of the Polish pig industry and its growing dependence on imports of piglets.
Źródło:
Zagadnienia Ekonomiki Rolnej; 2023, 375, 2; 1-21
0044-1600
2392-3458
Pojawia się w:
Zagadnienia Ekonomiki Rolnej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on optimization method of flotation kinetic model based on molybdenite particle size effect
Autorzy:
Wan, He
An, Yanni
Qu, Juanping
Zhang, Chonghui
Xue, Jiwei
Wang, Sen
Bu, Xianzhong
Powiązania:
https://bibliotekanauki.pl/articles/24085892.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
particle size effect
molybdenite
mathematical model
method of correction
Opis:
Flotation kinetic models can be applied to describe the flotation process and to predict mineral recoveries. However, the size composition of the target minerals in the feed ore fluctuates considerably, resulting in insufficient accuracy with flotation kinetic models. There have been many studies that focus on the investigation of flotation kinetics with different particle sizes, while the optimization methods for flotation kinetic models based on particle size effects have not been reported. In this paper, flotation tests, optical microscope observations, and particle size analysis were used to identify the reasons for the decrease in accuracy of the flotation kinetic model due to changes in the composition of molybdenite particle size. Additionally, an optimization method for the flotation kinetic model was developed based on the particle size effect. The test results show that the accuracy of the flotation kinetic model for fixed particle size minerals is very high, but the predicted results for flotation recoveries of different particle size mineral mixtures have large deviations. The poor accuracy might be due to the autogenous carrier effect caused by the particle size composition fluctuating considerably. The optimization method for the flotation kinetic model is based on the particle size effect. The model can accurately describe the flotation process of molybdenite with different size compositions of molybdenite and predict the flotation recovery of molybdenite.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 2; art. no. 163004
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Potential Application of the GNSS Leveling Method in Local Areas by Means of Sector Analysis
Autorzy:
Fedorchuk, Alina
Powiązania:
https://bibliotekanauki.pl/articles/2105518.pdf
Data publikacji:
2022
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
global geoid model
GNSS leveling
errors of geoid model
correction
Opis:
The purpose of this work is to perform the comparison of heights of global geoid models EGM08, EIGEN-6C4, GECO, and XGM2019e based on sector analysis that are obtained relative to the ellipsoid WGS84 and GRS80 in order to implement the method of GNSS leveling in local areas. The heights of the global geoid models determined from the ellipsoid WGS84 should be reduced by −41 cm ("œzero-degree term") in order to scale them to the calculated geoid by GNSS leveling. Heights determined from the ellipsoid GRS80 should be increased by +52 cm. Spatial analysis of the heights of geoid models in the relative system for the northern territory shows that the standard deviation of the heights of geoid models is 13.6 cm, and for the southern territory it is 36.5 cm. The elevation errors of the geoid models in the relative system were estimated to be standard deviations of 2.9 cm within the northern area and 2.3 cm within the southern one. The root mean square values of initial errors of the models EGM08, EIGEN-6C4, GECO, and XGM2019e are 8.6 cm, 4.6 cm, 4.4 cm, and 3.8 cm, respectively, and standard deviation values are 2.0 cm, 2.2 cm, 3.2 cm, and 2.4 cm. The paper also performs a sector analysis of the geoid model errors in order to correct them for the application of the GNSS leveling method within the research area. The standard deviations of the residual error of the corrected model heights are 1.8 cm, 1.9 cm, 2.5 cm, and 2.0 cm for EGM08, EIGEN-6C4, GECO, and XGM2019e. The root mean square values of these residual errors for the geoid models are 1.9 cm, 2.0 cm, 2.5 cm, and 2.0 cm, respectively.
Źródło:
Geomatics and Environmental Engineering; 2022, 16, 3; 41--55
1898-1135
Pojawia się w:
Geomatics and Environmental Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of climate variability on yield of maize and yam in Cross River State, Nigeria: An autoregressive distributed lag bound approach
Autorzy:
Edet, E. O.
Udoe, P. O.
Isong, I. A.
Abang, S. O.
Ovbiroro, F. O.
Powiązania:
https://bibliotekanauki.pl/articles/1031443.pdf
Data publikacji:
2021
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Sustainable development
error correction model
food security
yield
Opis:
The study examined the impact of climate variability on yield of maize and yam in Cross River State, Nigeria. The specific objectives of the study were to determine the long-run and short-run impact of climate variability factors on yields of maize and yam. Data were sourced from the Nigerian Meteorological Agency (NiMeT) and Cross River State Ministry of Agriculture spanning from 1990-2016. Data obtained were analyzed using inferential statistics. Precisely, the model was estimated by the Ordinary Least Squares (OLS) multiple regression technique, which is within the Autoregressive Distributed Lag Bound approach and error correction testing framework. Both model-1 (maize yield) and model-2 (yam yield) passed through the conditions of the diagnostics and stability test. The study revealed that climate variables had a significant impact on maize yield both in the long and short-run. Based on the findings, it was concluded that proactive measures should be put in place to aid crop farmers adapt to the prevailing and looming threats of climate variability for the purpose of attaining the State’s food security balance sheet. To sustain this drive, an institutional and infrastructural support system is advocated in order to meet one of the goals of sustainable development agenda of the United Nations. Policy recommendations on how to cushion the impact of climate variability on the prescribed crops have been appropriately cited.
Źródło:
World News of Natural Sciences; 2021, 36; 60-74
2543-5426
Pojawia się w:
World News of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of international trade on employment in orange industry of South Africa
Autorzy:
Molepo, Nkoti Solly
Belete, Abenet
Hlongwane, Jan
Powiązania:
https://bibliotekanauki.pl/articles/1886408.pdf
Data publikacji:
2021-07-04
Wydawca:
Uniwersytet Przyrodniczy w Poznaniu. Wydawnictwo Uczelniane
Tematy:
South African orange industry
employment, wages
international trade
Johansen cointegration
vector error
correction model
Opis:
The purpose of the study is to analyse the long-run and short-run dynamic relations amongst total employment (lnEMPGt), export output (EXPOt) and import output (IMPOt) from 1990 to 2018, by applying a time-series analysis. The study adopts the secondary data for total employment from the Citrus Growers Association of South Africa, while both export and import output were sourced from the Global Trade Atlas. The multivariate cointegration approach is adopted in the study to identify any causal relationships amongst the concerned variables. The chosen optimum lag selection criterion was the Akaike Information Criterion (AIC) due to its association dependence on the log-likelihood ratio. The third lag was selected for the entire analysis. The results from the cointegration test and the Vector Error Correction Model (VECM) suggest a positive long-run effect between total employment and export output, while import output is negatively associated with total employment. The adjustment term of lnEMPGt, EXPOt and IMPOt suggests that the previous year’s errors are corrected for the current year at a convergence speed of 0.002, 1.11 and 25.37 percentage points, respectively. The results of the Granger causality test show that there are bidirectional causality effects between export output and total employment in the long run, while there are no causality effects between import output and total employment. The overall conclusion is that export outputs positively impact employment, while import outputs impact it negatively in the South African orange industry.
Źródło:
Journal of Agribusiness and Rural Development; 2021, 60, 2; 193-201
1899-5241
Pojawia się w:
Journal of Agribusiness and Rural Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Long-term relationship estimation and coupling/decoupling analysis between motorway traffic and Gross Value Added. Specification of an ARDL cointegration approach and application to the Italian case study
Autorzy:
Pampigna, Andrea
Mauro, Raffaele
Powiązania:
https://bibliotekanauki.pl/articles/2067397.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
toll roads
motorway
traffic
cointegration
transport studies
error-correction model
Italian case study
drogi płatne
ruch na autostradzie
kointegracja
badania transportowe
model korekcji błędów
studium przypadku włoskie
Opis:
As transportation is an activity derived from spatial complementarities between a certain supply at an origin and a certain demand at a destination, according to a general axiom it seems that economic activities entail transport demand. In this perspective, an essential analysis deals with the quantification of the relationships between transport demand and certain socioeconomic variables. Elasticity is a concept widely used in transport economics as a measure of the responsiveness of transport demand concerning different factors represented as independent variables in an econometric model and coupling/decoupling concepts have been proposed in literature. This paper deals with the estimation of elasticities of motorway traffic demand based on Gross Value Added (GVA), and the consequent investigation of coupling/decoupling situation. The analysis is based on the application of an Autoregressive-Distributed Lag (ARDL) cointegration model with the F-bound test and of the related Error Correction model. Starting from the general ARDL model and the methodology for the verification of its robustness, the same model is applied to the Italian toll road network. The time series of GVA for goods and services and the overall length of the toll network from 1995 to 2019 are considered as explanatory variables of the total annual distance traveled by light and heavy vehicles. The various tests in the ARDL framework show a cointegration between the variables, under the fulfillment of all the diagnostic requirements. In this way, the long-term elasticities and the short-term adjustment dynamics are estimated separately for the goods and services components of GVA, and light and heavy vehicles. Starting from stable estimates of elasticities, the long-term coupling and decoupling effects between motorway traffic of light and heavy vehicles and the national production of goods and services can be shown. The paper, as well as providing an updated picture of the Italian situation, identifies a methodological framework that can be transferred to other contexts for a sector of great interest to investors, such as the motorway sector. All this can be useful to meet the needs of numerous stakeholders, who want to deepen the links between the economic cycle and traffic demand on toll motorways.
Źródło:
Archives of Transport; 2021, 60, 4; 39--56
0866-9546
2300-8830
Pojawia się w:
Archives of Transport
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trade liberalization policy and competitiveness of cocoa beans exports in Nigeria (1961-2017)
Autorzy:
Obi-Egbedi, O.
Hussayn, J.A.
Oluwatayo, I.B.
Powiązania:
https://bibliotekanauki.pl/articles/2080922.pdf
Data publikacji:
2021
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
cocoa
competitiveness
market share
trade liberalization policy and vector error
correction model
Opis:
The cocoa sector in Nigeria has experienced decline in production, yield, exports coupled with its inability to attain global standards and targets and, gradual loss of competitiveness at the world market. Trade liberalization was government’s panacea to the sector’s problem although, cocoa competitiveness remains an issue since liberalization. Therefore, the relationship between trade liberalization policy and competitiveness of Nigeria’s cocoa exports was examined in this study using data for the period 1961-2017. Cocoa market share was used to measure competitiveness while analytical tools employed were: ADF test, Johansen co-integration test and the vector error correction model (VECM). Market share, quantity of cocoa export and inflation rate were stationary at original level while others, at first difference. The co-integration test showed seven co-integrating equations. Trade liberalization policy was found to be an important driver of competitiveness. In addition, area harvested, production quantity and export quantity positively influenced competitiveness while world price of cocoa, interest rate on agricultural loans, exchange rate and trade liberalization influenced negatively. Therefore, appropriate trade policy formulation and implementation is recommended while, specific attention should be paid to monetary policies and cocoa production by the government.
Źródło:
Zeszyty Naukowe Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie. Problemy Rolnictwa Światowego; 2021, 21[36], 1; 4-15
2081-6960
Pojawia się w:
Zeszyty Naukowe Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie. Problemy Rolnictwa Światowego
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compound Channel’s Cross-section Shape Effects on the Kinetic Energy and Momentum Correction Coefficients
Autorzy:
Ghanbari-Adivi, Elham
Powiązania:
https://bibliotekanauki.pl/articles/1837762.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
CES model
compound channel
FCF
floodplain
kinetic energy correction coefficient
momentum correction coefficient
Opis:
Since accurate estimation of the flow kinetic energy (α) and momentum (β) is not easily possible in compound channels, determining their accurate correction coefficients is an important task. This paper has used the “flood channel facility (FCF)” data and the “conveyance estimate system (CES)” model (which is 1D, but considers a term related to the secondary flow) to study how the floodplain width and the main channel wall slope and asymmetry affect the values of α and β. Results have shown that their maximum values at the highest floodplain width are, respectively, 1.36 and 1.13 times of those at the lowest case; an increase in the slope increased their maximum values by 1.05 and 1.01 times, respectively. The mean of error values showed that the CES model estimated the values α and β more accurately than the flow discharge. The maximum differences between the estimated and experimental values were 12.14% for α and 4.3% for β; for the flow discharge, it was 24.4%.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2020, 67, 1-4; 55-71
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rationalization of the energy consumption of road transport for sustainable development
Autorzy:
Szaruga, Elżbieta
Powiązania:
https://bibliotekanauki.pl/articles/135696.pdf
Data publikacji:
2020
Wydawca:
Akademia Morska w Szczecinie. Wydawnictwo AMSz
Tematy:
energy consumption
freight road transport
rationalization
steady-state economy
sustainable development
vector error correction model
Opis:
This paper presents an approach to rationalize the energy consumption of road transport towards sustainability in a steady-state economy. The research hypothesis is that the rationalization of the energy consumption of road transport is affected by drift and shocks, which desynchronizes the adjustment mechanism from equilibrium. The objective of this research was to incorporate the model of energy consumption of road freight transport with the goals of sustainability by considering ecological and constructivist rational orders, the issue of order drift, and the occurrence of shocks. The research investigated Poland from the first quarter of 2004 to the fourth quarter of 2018. A model for rationalizing the energy consumption of road transport was constructed using the vector error correction model and cointegration techniques. The model revealed one cointegrating relationship and showed statistically significant unlimited drift. The level of changes to long-term equilibrium appeared respectively for GDP – 1.8%, PPI for energy – 7.3%, and for energy consumption – 10.9%. We observed a weak sustainability between the energy consumption of road transport and GDP and a strong sustainability between energy consumption of road transport and PPI energy. It was determined that price shocks had a positive impact (at the estimated point level around 0.06) and supply and demand shocks had a negative impact (at the level estimated point around –3).
Źródło:
Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2020, 62 (134); 36-42
1733-8670
2392-0378
Pojawia się w:
Zeszyty Naukowe Akademii Morskiej w Szczecinie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studying the Stock Market – Economic Activity Nexus in Poland with a VAR‑VECM Approach
Badanie współzależności pomiędzy rynkiem akcji a poziomem aktywności gospodarczej w Polsce z wykorzystaniem metodologii VAR‑VECM
Autorzy:
Pietraszewski, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/655935.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
WIG
produkt krajowy brutto
autoregresja wektorowa
kointegracja
model korekty błędem
Gross Domestic Product
vector autoregression
cointegration
error correction model
Opis:
W artykule omówiono związki pomiędzy koniunkturą giełdową a realną aktywnością gospodarczą oraz przedstawiono wyniki badania współzależności pomiędzy zmianami głównego indeksu akcji na GPW w Warszawie (WIG) oraz PKB w Polsce w latach 1995–2019. W wielu studiach empirycznych dla krajów wysoko rozwiniętych wykazano istnienie nie tylko dynamicznych interakcji krótkookresowych, ale również długoterminowej relacji kointegrującej pomiędzy poziomami indeksu i produktu. Dotychczasowe badania dla Polski wskazywały głównie na związki krótkookresowe pomiędzy stopami zwrotu z akcji a zmianami aktywności gospodarczej, podczas gdy dowody na istnienie długookresowej relacji kointegrującej są jak dotąd nieliczne. W artykule zastosowano metodologię VAR‑VECM oraz procedurę Johansena do badania kointegracji dla znacznie dłuższego szeregu danych kwartalnych niż w prowadzonych do tej pory badaniach. Badanie wykazało, że stopy zwrotu z akcji są przyczyną w sensie Grangera dla zmian PKB, przy czym wyprzedzenie w czasie sięga do trzech kwartałów. Znaleziono również dowody na istnienie długoterminowej relacji kointegrującej.
The paper discusses the links between stock market performance and real economic activity and presents results of an empirical inquiry into dynamic relationships between the main stock index quoted on the Warsaw Stock Exchange (WIG) and GDP in Poland over the years 1995–2019. In many empirical studies for highly developed countries not only short‑run dynamic interactions but also a long‑run cointegrating relationship between the stock index and output have been found. Previous studies for Poland reported mainly short‑run linkages between stock returns and changes of economic activity whereas the evidence for a long‑run cointegrating relationship is still quite scarce. In this paper, the VAR‑VECM methodology with the Johansen tests for cointegration is used to study a substantially longer quarterly data interval than has been investigated so far. Research results show that stock returns Granger‑cause GDP growth with up to three‑quarters lead. The evidence for the existence of a long‑term cointegrating relationship has also been found.
Źródło:
Acta Universitatis Lodziensis. Folia Oeconomica; 2020, 3, 348; 65-89
0208-6018
2353-7663
Pojawia się w:
Acta Universitatis Lodziensis. Folia Oeconomica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The response of Zimbabwe tobacco exports to real exchange rates volatility
THE RESPONSE OF ZIMBABWE TOBACCO EXPORTS TO REAL EXCHANGE RATES VOLATILITY
Autorzy:
Mutodi, Knowledge
Chuchu, Tinashe
Maziriri, Eugine Tafadzwa
Powiązania:
https://bibliotekanauki.pl/articles/1892227.pdf
Data publikacji:
2020-07-08
Wydawca:
Uniwersytet Przyrodniczy w Poznaniu. Wydawnictwo Uczelniane
Tematy:
Real exchange rate (RER)
Real exchange rate volatility (RERV)
Vector error correction model (VECM)
Opis:
The focus of this study was on investigating the response of tobacco exports to real exchange rates and real exchange rate volatility and other factors in Zimbabwe using secondary data spanning from 1980 to 2019. Bilateral nominal exchange rates and time-variant weights of Zimbabwe’s 10 major trading partners were calculated and used to compute the real exchange rate index. The time-dependent weighting system was used to better represent the evolution of trade patterns in the index. The arithmetic method was employed for computing the index. Generalized autoregressive conditional heteroskedasticity (GARCH) and autoregressive conditional heteroscedasticity (ARCH) models were used to generate the real exchange rate volatility index. The export response function was adopted as the tobacco exports response model. The variables in the tobacco exports response model were the realworld Gross Domestic Product (GDP), real exchange rate, terms of trade, real exchange rate volatility and dollarization. A vector error correction model (VECM) was used to estimate the response of tobacco exports to real exchange rate, real exchange rate volatility and other factors. The VECM results indicated that real world GDP was insignificant in both the short and long run. In the long run, the real exchange rate appreciation had a negative impact on tobacco exports. Conversely, in the short run, the depreciation of real exchange rate had a positive impact on tobacco exports. Hence, the government has to adopt other mechanisms that reduce uncertain movements of exchange rates.
Źródło:
Journal of Agribusiness and Rural Development; 2020, 56, 2; 201-219
1899-5241
Pojawia się w:
Journal of Agribusiness and Rural Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A price transmission analysis of pasteurised liquid milk in South Africa: granger causility approach
Autorzy:
Ramoshaba, Tshegofatso
Belete, Abanet
Hlongwane, Johanes Jan
Powiązania:
https://bibliotekanauki.pl/articles/1902627.pdf
Data publikacji:
2019-12-28
Wydawca:
Uniwersytet Przyrodniczy w Poznaniu. Wydawnictwo Uczelniane
Tematy:
price transmission
Granger causality
pasteurized liquid milk
Vector Error Correction model
Opis:
Price transmission studies have become increasingly important in Sub-Saharan Africa over the past decades because of its nature of providing clear and insightful information into these markets. In this study, the price transmission mechanism is described with an agricultural product within the dairy industry, namely pasteurized liquid milk. The aim of this study was to investigate and analyze the nature of the price transmission mechanism for pasteurized liquid milk in South Africa. The study used secondary time series data that covered a sample size of 17 years (2000–2016) for pasteurized liquid milk. The Granger causality test and the Vector Error Correction Model were used for data analysis. The Granger causality tests suggest that a bidirectional causal relationship exists between processor and farmgate prices, and also between retail and processor prices. On the other hand, retail prices were found to have a unidirectional causality effect on farmgate prices. The VECM results showed asymmetric price transmission, implying that retailers and processors react quicker to a price increase than to a price decrease. A price monitoring policy is suggested to be put in place in order to protect the consumers from unfair prices passed on by the retailers.
Źródło:
Journal of Agribusiness and Rural Development; 2019, 54, 4; 345-353
1899-5241
Pojawia się w:
Journal of Agribusiness and Rural Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An improved GM(1.1) model with background value optimization and Fourier-series residual error correction and its application in cost forecasting of coal mine
Ulepszony model GM(1,1) z optymalizacją wartości tła i korekcją błędów resztkowych szeregów Fouriera oraz jego zastosowanie w prognozowaniu kosztów kopalni węgla kamiennego
Autorzy:
Liu, Di
Li, Guoqing
Chanda, Emmanuel K.
Hu, Nailian
Ma, Zhaoyang
Powiązania:
https://bibliotekanauki.pl/articles/216495.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:
cost forecasting
dynamic grey model
background value optimization
Fourier series
residual error correction
prognozowanie kosztów
dynamiczny model szary
optymalizacja wartości tła
korekcja błędów resztkowych
szeregi Fouriera
Opis:
This paper researches the application of grey system theory in cost forecasting of the coal mine. The grey model (GM(1.1)) is widely used in forecasting in business and industrial systems with advantages of minimal data, a short time and little fluctuation. Also, the model fits exponentially with increasing data more precisely than other prediction techniques. However, the traditional GM(1.1) model suffers from the poor anti-interference ability. Aimed at the flaws of the conventional GM(1.1) model, this paper proposes a novel dynamic forecasting model with the theory of background value optimization and Fourier-series residual error correction based on the traditional GM(1.1) model. The new model applies the golden segmentation optimization method to optimize the background value and Fourier-series theory to extract periodic information in the grey forecasting model for correcting the residual error. In the proposed dynamic model, the newest data is gradually added while the oldest is removed from the original data sequence. To test the new model’s forecasting performance, it was applied to the prediction of unit costs in coal mining, and the results show that the prediction accuracy is improved compared with other grey forecasting models. The new model gives a MAPE & C value of 0.14% and 0.02, respectively, compared to 1.75% and 0.37 respectively for the traditional GM(1.1) model. Thus, the new GM(1.1) model proposed in this paper, with advantages of practical application and high accuracy, provides a new method for cost forecasting in coal mining, and then help decision makers to make more scientific decisions for the mining operation.
W pracy zbadano zastosowanie teorii szarego systemu w prognozowaniu kosztów kopalni węgla. Szary model (GM(1,1)) jest szeroko wykorzystywany w prognozowaniu w systemach biznesowych i przemysłowych z niewielką ilością danych, krótkim czasem i nieznacznymi wahaniami. Ponadto model dopasowuje wykładniczo dane bardziej dokładnie niż inne techniki prognozowania. Jednak tradycyjny model GM(1,1) ma słabą zdolność przeciwdziałania zakłóceniom. Mając na uwadze wady konwencjonalnego modelu GM(1,1), w artykule zaproponowano – w oparciu o tradycyjny model GM(1,1) – nowy model dynamicznego prognozowania z teorią optymalizacji wartości tła i korektą błędów resztkowych szeregów Fouriera. Nowy model stosuje metodę optymalizacji złotej segmentacji do optymalizacji wartości tła oraz teorię szeregów Fouriera w celu wyodrębnienia okresowych informacji w szarym modelu prognozowania, aby skorygować błąd resztkowy. W proponowanym modelu dynamicznym najnowsze dane są stopniowo dodawane, podczas gdy najstarsze – usuwane z oryginalnej sekwencji danych. Aby przetestować dokładność prognozowania nowego modelu, zastosowano go do prognozowania kosztów jednostkowych pozyskania węgla, a wyniki pokazują, że dokładność prognozowania jest lepsza w porównaniu z innymi szarymi modelami prognozowania. Nowy model daje wartości MAPE & C wynoszące odpowiednio 0,33% i 0,07, w porównaniu z odpowiednio 1,1% i 0,3 dla tradycyjnego modelu GM(1,1). Zatem zaproponowany w artykule, ulepszony model GM(1,1) z zaletami praktycznego zastosowania i wysoką dokładnością, jest nową metodą prognozowania kosztów w górnictwie węgla, która ułatwia decydentom podejmowanie decyzji ugruntowanych naukowo dotyczących operacji pozyskania węgla.
Źródło:
Gospodarka Surowcami Mineralnymi; 2019, 35, 3; 75-98
0860-0953
Pojawia się w:
Gospodarka Surowcami Mineralnymi
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Krótko- i długookresowe skorygowane krańcowe skłonności do konsumpcji : gospodarka Polski w latach 1995-2018
Short and Long-run Corrected Marginal Propensity to Consume : Polish Economy in the Period 1995-2018
Autorzy:
Ossowski, Jerzy Czesław
Powiązania:
https://bibliotekanauki.pl/articles/1826415.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska
Tematy:
error correction mechanism
autoregressive global consumption model
short-run
corrected marginal propensity to consume
long-run corrected marginal propensity to consume
mechanizm korekty błędem
autoregresyjny model konsumpcji globalnej
krótkookresowa skorygowana krańcowa skłonność do konsumpcji
długookresowa skorygowana krańcowa skłonność do konsumpcji
Opis:
In the introductory part of the article – referring to Keynes’ theory – basic macroeconomic relations between global consumption and gross domestic product are discussed and defined. Next, an analysis of statistical information on private consumption expenditure of households (C) and global consumption expenditure of the society (CO) against the background of gross domestic product (GDP) in Poland in 1995–2018 was carried out. The analysis of empirical material carried out allowed formulating preliminary assumptions regarding the analyzed macro-dependencies. In the main theoretical part of the article – referring, inter alia, to the conclusions from the empirical part of the analysis – the research hypothesis was formulated, according to which: the relationship between real consumption (C or CO) and gross domestic product (GDP) is linear, inertial and subject to a correction mechanism. To verify the hypothesis, an autoregressive model of global consumption was formulated, which was subject to the error correction mechanism (ECM). Based on the analytical form of the considered model, the following measures were defined: — short-run, immediate uncorrected marginal propensity to consume (SrMPCim), — short-run corrected marginal propensity to consume (SrMPCcrd), — long-run corrected marginal propensity to consume (LrMPCcrd). In addition, a switch trend function was defined that was assigned to the dynamic error correction model (ECM) under consideration. In the empirical part of the article, two versions of the considered autoregressive consumption model with a correction mechanism were considered. In the first version of the model, real private consumption of households (C) was dependent on domestic product (GDP). On the other hand, the second version makes the total consumption of the society (CO) dependent on the domestic product (GDP). Both versions of the model were estimated, verified and interpreted. The analysis of the estimated versions of the model confirmed the theoretical research hypothesis according to which real consumption: — is linearly dependent on the gross domestic product, — is inertial, — it is corrected in time.
We wstępnej części artykułu - odwołując się do teorii Keynesa - omówiono i zdefiniowano podstawowe relacje makroekonomiczne pomiędzy konsumpcją globalną a produktem krajowym brutto. W następnej kolejności przeprowadzono analizę informacji statystycznych dotyczących prywatnych wydatków konsumpcyjnych gospodarstw domowych (C) oraz globalnych wydatków konsumpcyjnych społeczeństwa (CO) na tle produktu krajowego brutto (PKB) w Polsce w latach 1995-2018. Przeprowadzona analiza materiału empirycznego pozwoliła na sformułowanie wstępnych założeń dotyczących analizowanych makrozależności. W zasadniczej części teoretycznej artykułu - odwołując się między innymi do wniosków z części empirycznej analizy - sformułowano hipotezę badawczą, zgodnie z którą: zależność pomiędzy konsumpcją realną (C lub CO) a produktem krajowym brutto (PKB) ma charakter liniowy, inercyjny oraz podlega mechanizmowi korekty. Celem zweryfikowania postawionej hipotezy sformułowano autoregresyjny model konsumpcji globalnej, który podlegał mechanizmowi korekty błędem (ECM). Na podstawie postaci analitycznej rozważanego modelu zdefiniowano następujące mierniki: — krótkookresową, natychmiastową nieskorygowaną krańcową skłonność do konsumpcji (SrKSKim), — krótkookresową skorygowaną krańcową skłonność do konsumpcji (SrKSKcrd), — długookresową skorygowaną krańcową skłonność do konsumpcji (LrKSKcrd). Ponadto zdefiniowano funkcję trendu przełącznikowego, który przyporządkowano rozważanemu dynamicznemu modelowi korekty błędem (ECM).W części empirycznej artykułu rozpatrzono dwie wersje rozważanego autoregresyjnego modelu konsumpcji z mechanizmem korekty. W pierwszej wersji modelu uzależniono realną konsumpcję prywatną gospodarstw domowych (C) od produktu krajowego (PKB). Z kolei w drugiej wersji uzależniono realną konsumpcję całkowitą społeczeństwa (CO) od produktu krajowego (PKB). Obie wersje modelu oszacowano, zweryfikowano oraz zinterpretowano. Przeprowadzona analiza oszacowanych wersji modelu potwierdziła sformułowaną w części teoretycznej hipotezę badawczą zgodnie z którą realna konsumpcja:-jest liniowo zależna od produktu krajowego brutto,-ma charakter inercyjny,-jest korygowana w czasie.
Źródło:
Przedsiębiorstwo we współczesnej gospodarce - teoria i praktyka; 2019, 2, 29; 27-57
2084-6495
Pojawia się w:
Przedsiębiorstwo we współczesnej gospodarce - teoria i praktyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Working model of a physical education based spastic movement disorder correction system aimed at tender age children
Autorzy:
Nikolay, Moga,
Powiązania:
https://bibliotekanauki.pl/articles/890463.pdf
Data publikacji:
2019-12-30
Wydawca:
Akademia Pedagogiki Specjalnej im. Marii Grzegorzewskiej. Wydawnictwo APS
Tematy:
system
model
structure
interconnection
correction
goal
efficiency
spastic syndrome
Opis:
The article describes modern modeling of physical rehabilitation processes for persons with musculoskeletal system disorders, and reveals a significant deficiency of this aspect in modern rehabilitation systems. Most of the developments in this field are based on practical, empirical experience of rehabilitation activities for a specific category of children. This is understandable but does not prevent mistakes in the strategy and tactics of long-term physical rehabilitation. It is necessary to have clear conceptual guidelines for the most effective process of physical rehabilitation concerning tender age children with spastic movement disorders. This can be achieved by pre-modeling the system of adaptive physical education of babies with spastic paresis. A structured and logically constructed model construction of the rehabilitation system includes four effective blocks: monitoring of physical development and spastic motor disorders (I), which is itself divided into medical, pedagogical, psychological; corrective measures (II) strategies and tactics, including a general correction program for the typological subgroup of children with spastic paresis and an individual correction program for normalizing the motor status of a particular child; correction of motor disorders of spastic type (III), which provides the means and methods of correctional physical education of tender age children with spastic motor disorders. The latter include: game, hypercorrection, contraindications, sufficient repetition of exercises, objectivity, and individual load differentiation; control and correction of the correction process (IV), which provides for permanent control over the components of the motor rehabilitation system, starting with the monitoring of physical development and ending with the peculiarities of the work correction process by means of physical education. Intra-system relations between all components of the working model are envisaged, and the priority of individual components of a perspective modeled system is considered. The model provides an invariant component of the system of adaptive physical education, universal for different children with spastic syndrome, as well as a variational component, which provides differentiation and individualization of corrective tactics for each specific child and its peculiarities of psychophysical development. The pre-designed working model of the correction system of movement disorders spastic forms of tender age children by physical education means will be tested in the process of forming a pedagogical experiment, which will make the necessary corrections both in the structural construction of this general rehabilitation system and in the substantive filling of its internal components.
Źródło:
International Journal of Pedagogy, Innovation and New Technologies; 2019, 6(2); 123-132
2392-0092
Pojawia się w:
International Journal of Pedagogy, Innovation and New Technologies
Dostawca treści:
Biblioteka Nauki
Artykuł
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