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Tytuł:
Monetary determinants of output dynamics in the light of the structural vector-autoregressive SVAR model: a Keynesian approach
Autorzy:
Kołbyko, Patryk Norbert
Powiązania:
https://bibliotekanauki.pl/articles/20312085.pdf
Data publikacji:
2024
Wydawca:
Uniwersytet Ekonomiczny w Katowicach
Tematy:
endogenous money creation
macroeconometrics
monetary theory of the business cycle
time series decomposition
structural vector-autoregressive model
Opis:
PURPOSE: The purpose of the following paper is to analyze and empirically verify the monetary theory of business cycles as a mechanism for the interaction of the dynamics of production and money supply based on the example of the Polish economy. In order to identify and mitigate the risk of economic fluctuations as a function of the response of the central bank, it is necessary to conduct an extensive analysis of the indirect mechanism of transmission of monetary impulses on production in the economy. DESIGN/METHOD: Empirical analysis was carried out by estimating a macroeconometric time series model taking into account the inductive information based on the Keynesian theory the structural vector-autoregressive SVAR model. The stochastic process included in the study was based on statistical data of Poland, which were obtained from the cyclical reports: ‘Preliminary estimate of gross domestic product’ and ‘Quarterly accounts of gross domestic product in 2017-2021’, Poland’s Central Statistical Office and the National Bank of Poland's databases for the time interval of 2007.Q1-2022.Q2. RESULTS/FINDINGS: The applied empirical analysis positively verified the existence of an indirect monetary impulse transmission mechanism in Poland’s economy. The obtained research has positively verified the compatibility of the monetary theory of the business cycle in terms of the Keynesian theory with the macroeconomic reality in Poland. The results of the research justify the measures to mitigate the risk of economic instability and impose a requirement for discretionary policy by the National Bank of Poland. ORIGINALITY/VALUE: The following work addresses an important element of the macroeconomic analysis, specifically the monetary theory of the business cycle. The originality of the work stems from the empirical attempt to verify the monetary theory of the business cycle taking into account the indirect mechanism of transmission of monetary impulses on the grounds of the statistical data from the Polish economy.
Źródło:
Studies in Risk and Sustainable Development; 2024, 398; 1-19
2720-6300
Pojawia się w:
Studies in Risk and Sustainable Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the vector-autoregression VAR model in the analysis of unemployment hysteresis in the context of Okun’s Law
Autorzy:
Kołbyko, Patryk
Powiązania:
https://bibliotekanauki.pl/articles/2207120.pdf
Data publikacji:
2023-02-22
Wydawca:
Uniwersytet Ekonomiczny w Poznaniu
Tematy:
vector-autoregression model VAR
time series analysis
hysteresis in the labour market
Okun’s Law
macroeconometrics
Opis:
Unemployment is an important macroeconomic issue both in theoretical terms and for economic reality. On the theoretical ground, the unemployment rate, which is a measure of the share of unemployed units of the labour supply in the economy, determines the output gap at a certain adjustment parameter determined by the marginal productivity of labour. One of the causes of rising or persistent unemployment in the economy is the phenomenon of unemployment hysteresis, which occurs as a result of changes in the marginal disutility of labour, the strength of the wage bargain and other exogenous conditions arising in previous periods. The purpose of the study conducted in the following paper is to investigate the phenomenon of hysteresis in the labour market by analysing the significance of the impact of the unemployment rate in previous periods. In addition, the work aims to study Okun’s Law as an effect of production dynamics on the unemployment rate. The study of the dependence was carried out through the estimation of a macroeconometric time series model—vector-autoregression (VAR) on the example of statistical data for Poland obtained from Statistics Poland (Stat.gov.pl) and complied raports about national accounts in the quarterly sequence for the years 2015–2021. The period of the study was arbitrarily selected with the observation of business cycle fluctuations in the above time frame. Empirical analysis of selected structural parameters through estimation of the vector-autore- gression model showed a significant influence of the time series in the formation of the unemployment rate, which confirms the influence of the analysed phenomenon of hysteresis in the labour market. In addition, the vector-autoregression model for inter- val forecasting through the use of dynamic prediction proved to be a posteriori accurate forecasting model of the unemployment rate in the Polish economy.
Źródło:
Research Papers in Economics and Finance; 2022, 6, 2; 68-85
2543-6430
Pojawia się w:
Research Papers in Economics and Finance
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic analysis of a mechatronic drive system with an induction motor
Autorzy:
Cao, Yongdi
Liu, Xiaohong
Powiązania:
https://bibliotekanauki.pl/articles/2200885.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
dynamic model
electromechanical system
vector control
optimization
rotor
Opis:
The paper presents research findings in the modelling and optimization of dynamic parameters of mechatronic systems with an induction motor. A mathematical model was developed to analyze currents in dynamic states of squirrel-cage rotors in the case of a line-to-line fault. The findings were verified experimentally using calculations for a 1.5 kW three-phase induction motor. The equations for a stationary 0x, 0y coordinate system relating to the stator were derived. The set of design variables selected in the optimization process contained parameters describing design features of the gear shafts and control units settings.
Źródło:
Journal of Theoretical and Applied Mechanics; 2023, 61, 2; 245--258
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fault location of distribution network with distributed generation based on Karrenbauer transform and support vector machine regression
Autorzy:
Wang, Siming
Zhao, Kaikai
Powiązania:
https://bibliotekanauki.pl/articles/24202729.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
distributed generation
distribution network fault location
fault type
Karrenbauer transform
agent prediction model
SVR
support vector regression
Opis:
As the capacity and scale of distribution networks continue to expand, and distributed generation technology is increasingly mature, the traditional fault location is no longer applicable to an active distribution network and "two-way" power flow structure. In this paper, a fault location method based on Karrenbauer transform and support vector machine regression (SVR) is proposed. Firstly, according to the influence of Karrenbauer transformation on phase angle difference before and after section fault in a low-voltage active distribution network, the fault regions and types are inferred preliminarily. Then, in the feature extraction stage, combined with the characteristics of distribution network fault mechanism, the fault feature sample set is established by using the phase angle difference of the Karrenbauer current. Finally, the fault category prediction model based on SVR was established to solve the problem of a single-phase mode transformation modulus and the indistinct identification of two-phase short circuits, then more accurate fault segments and categories were obtained. The proposed fault location method is simulated and verified by building a distribution network system model. The results show that compared with other methods in the field of fault detection, the fault location accuracy of the proposed method can reach 98.56%, which can enhance the robustness of rapid fault location.
Źródło:
Archives of Electrical Engineering; 2023, 72, 2; 461--481
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Medium- and long-term prediction of polar motion using weighted least squares extrapolation and vector autoregressive modeling
Autorzy:
Lei, Yu
Zhao, Danning
Guo, Min
Powiązania:
https://bibliotekanauki.pl/articles/27314482.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Centrum Badań Kosmicznych PAN
Tematy:
polar motion
prediction model
weighted least squares
vector autoregressive
Opis:
This article presents the application of weighted least squares (WLS) extrapolation and vector autoregressive (VAR) modeling in polar motion prediction. A piecewise weighting function is developed for the least squares (LS) adjustment in consideration of the effect of intervals between observation and prediction epochs on WLS extrapolation. Furthermore, the VAR technique is used to simultaneously model and predict the residuals of xp, yp pole coordinates for WLS misfit. The simultaneous predictions of xp, yp pole coordinates are subsequently computed by the combination of WLS extrapolation of harmonic models for the linear trend, Chandler and annual wobbles, and VAR stochastic prediction of the residuals (WLS+VAR). The 365-day-ahead xp, yp predictions are compared with those generated by LS extrapolation+univariate AR prediction and LS extrapolation+VAR modeling. It is shown that the xp, yp predictions based on WLS+VAR taking into consideration both the interval effect and correlation between xp and yp outperform those generated by two others. The accuracies of the xp predictions are 13.97 mas, 18.47 mas, and 20.52 mas, respectively for the 150-, 270-, and 365-day horizon in terms of the mean absolute error statistics, 36%, 24.8%, and 33.5% higher than LS+AR, respectively. For the yp predictions, the 150-, 270-, and 365-day accuracies are 15.41 mas, 21.17 mas, and 21.82 mas respectively, 27.4%, 11.9%, and 21.8% higher than LS+AR respectively. Moreover, the absolute differences of the WLS+VAR predictions and observations are smaller than the differences from LS+VAR and LS+AR, which is practically important to practical and scientific users, although the improvement in accuracies is no more than 10% relative to LS+VAR. The further comparison with the predictions submitted to the 1st Earth Orientation Parameters Prediction Comparison Campaign (1st EOP PCC) shows that while the accuracy of the predictions within 30 days is comparable with that by the most accurate prediction techniques including neural networks and LS+AR participating in the campaign for xp, yp pole coordinates, the accuracy of the predictions up to 365 days into the future are better than accuracies by the other techniques except best LS+AR used in the EOP PCC. It is therefore concluded that the medium- and long-term prediction accuracy of polar motion can be improved by modeling xp, yp pole coordinates together.
Źródło:
Artificial Satellites. Journal of Planetary Geodesy; 2023, 58, 2; 42--55
2083-6104
Pojawia się w:
Artificial Satellites. Journal of Planetary Geodesy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prognozowanie wskaźnika nagromadzenia odpadów w ujęciu zmian osobistych wydatków konsumpcyjnych za pomocą modelu wektorowo-autoregresyjnego
FORECASTING OF MUNICIPAL WASTE ACCUMULATION RATE IN THE APPROACH TO CHANGES IN PERSONAL CONSUMER EXPENDITURE BY MEANS OF A VECTOR-AUTOREGRESSIVE MODEL
Autorzy:
Bień, Jurand
Bień, Beata
Krawczyk, Piotr
Powiązania:
https://bibliotekanauki.pl/chapters/33534354.pdf
Data publikacji:
2023-12-07
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
analiza szeregów czasowych
model wektorowo-autoregresyjny
prognozo-wanie
wskaźnik nagromadzenia odpadów
wydatki konsumpcyjne
consumer expenditures
forecasting
time-series analysis
vector-autoregression model
waste accumulation rate
Opis:
Prognozowanie ilości wytwarzanych odpadów komunalnych jest ważne dla planowania, eksploatacji i optymalizacji prawidłowo funkcjonującego systemu gospodarki odpadami komunalnymi. Nie jest to jednak łatwe zadanie ze względu na szereg dynamicznych zmian będących wynikiem przeobrażeń demograficznych, społecznych, ekonomicznych, czasem wręcz nieprzewidywalnych. Początkowo do prognozowania stosowano głównie konwencjonalne, opisowe modele statystyczne prognozowania wytwarzania odpadów z uwzględnieniem czynników demograficznych i społeczno-ekonomicznych. Obecnie jednak coraz częściej metody te zastępowane są przez metody oparte na uczeniu maszynowym, które to stanowi podzbiór sztucznej inteligencji. Uczenie maszynowe to nic innego jak nauczenie komputerów, jak uczyć się na danych i doskonalić w miarę zdobywania doświadczenia. W niniejszej publikacji przeanalizowano zmiany wskaźnika nagromadzenie odpadów komunalnych w jego relacji do wydatków na osobistą konsumpcję w oparciu o dane pozyskane z Banku Danych Lokalnych (BDL) prowadzonego przez Główny Urząd Statystyczny. Analiza, a następnie prognoza przeprowadzona została z wykorzystaniem modelu wektorowo-autoregresyjnego, gdzie każda ze zmiennych opisana została osobnym równaniem modelu, w którym zmiennymi niezależnymi są opóźnienia wszystkich zmiennych zależnych. Uzyskane wyniki pokazały, że taka metoda może być z powodzeniem stosowana do prognozowania wskaźnika nagromadzenia odpadów w ujęciu zmian osobistych wydatków konsumpcyjnych przy przybliżonym poziomie 2,3% błędu średniokwadratowego (RMSE).
Forecasting the amount of municipal waste generated is important for the planning, operation and optimization of a properly functioning municipal waste management system. However, it is not an easy task due to a number of dynamic changes resulting from demographic, social and economic transformations, some of them unpredictable. Initially, mainly conventional, descriptive statistical models of forecasting waste generation, taking into account demographic and socio-economic factors, were used for prognosis. Currently more and more often these methods are replaced by methods based on machine learning, which is a subset of artificial intelligence. Machine learning teaches computers to learn from data and improve the model as they gain experience. The chapter analyses the changes in the municipal waste accumulation ratio in relation to expenditure on personal consumption based on data obtained from the Local Data Bank (LDB) run by the Polish Central Statistical Office. The analysis, and then the forecasting, was carried out with the use of a vector-autoregressive model, where each variable was described with a separate model equation, in which the independent variables are the delays of all dependent variables. The results showed that such a method can be successfully used to forecast the waste accumulation rate in terms of changes in personal consumption expenditure at an approximate level of 2.3% mean square error (RMSE).
Źródło:
Czysta energia i środowisko; 95-107
9788371939044
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A computationally low burden MPTC of induction machine without prediction loop and weighting factor
Autorzy:
Kiani, Babak
Powiązania:
https://bibliotekanauki.pl/articles/2173663.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
MPTC
model predictive torque control
induction motor
duty ratio
voltage vector
lookup table
weighting factor
modelowa predykcyjna kontrola momentu obrotowego
silnik indukcyjny
współczynnik wypełnienia impulsu
wektor napięcia
tabela przeglądowa
współczynnik ważenia
Opis:
This paper presents a novel method to overcome problems of finite set-model-based predictive torque control (MPTC) which has received a lot of attention in the last two decades. Tuning the weighting factor, evaluating a large number of switching states in the loop of the predictive control, and determining the duty cycle are three major challenges of the regular techniques. Torque and flux responses of deadbeat control have been developed to overcome these problems. In our method, firstly, the prediction stage is performed just once. Then, both the weighted cost function and its evaluation are replaced with only simple relationships. The relationships reduce torque ripple and THD of stator current compromisingly. In the next step, the length of the virtual vector is used to determine the duty cycle of the optimum voltage vector without any additional computations. The duty ratio does not focus on any relation or criteria minimizing torque or flux ripple. As a result, torque and flux ripples are reduced equally. The proposed duty cycle is calculated by using a predicted virtual voltage vector. Hence, no new computation is needed to determine the proposed duty cycle. Simulation and experimental results confirm both the steady and dynamic performance of the proposed method in all speed ranges.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 4; art. no. e142050
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Forecasting municipal waste accumulation rate and personal consumption expenditures using vector autoregressive (VAR) model
Autorzy:
Bień, Jurand
Powiązania:
https://bibliotekanauki.pl/articles/23966648.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Menedżerów Jakości i Produkcji
Tematy:
wskaźnik akumulacji odpadów
wydatki konsumpcyjne
prognozowanie
analiza szeregów czasowych
wielowymiarowe szeregi czasowe
model autoregresji wektorowej
waste accumulation rate
consumption expenditures
forecasting
time-series analysis
multivariate time series models
vector autoregression model
Opis:
Accurate forecasting of municipal solid waste (MSW) generation is important for the planning, operation and optimization of municipal waste management system. However, it’s not easy task due to dynamic changes in waste volume, its composition or unpredictable factors. Initially, mainly conventional and descriptive statistical models of waste generation forecasting with demographic and socioeconomic factors were used. Methods based on machine learning or artificial intelligence have been widely used in municipal waste projection for several years. This study investigates the trend of municipal waste accumulation rate and its relation to personal consumption expenditures based on the yearly data achieved from Local Data Bank (LDB) driven by Polish Statistical Office. The effect of personal consumption expenditures on the municipal waste accumulation rate was analysed by using the vector autoregressive model (VAR). The results showed that such method can be successfully used for this purpose with an approximate level of 2.3% Root Mean Square Error (RMSE).
Źródło:
Production Engineering Archives; 2022, 28, 2; 150--156
2353-5156
2353-7779
Pojawia się w:
Production Engineering Archives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model predictive direct power control of energy storage quasi-Z-source grid-connected inverter
Autorzy:
Tang, Min'an
Yang, Shangmei
Zhang, Kaiyue
Wang, Qianqian
Liu, Chenggang
Dong, Xuewang
Powiązania:
https://bibliotekanauki.pl/articles/2042769.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
quasi Z-Source
inverter
energy storage
power control
model predictive
space vector
Opis:
In order to overcome the shortcoming of large switching losses caused by variable switching frequency appears in the conventional finite control set model predictive control (FCS-MPC) algorithm, a model predictive direct power control (MP-DPC) for an energy storage quasi-Z-source inverter (ES-qZSI) is proposed. Firstly, the power prediction model of the ES-qZSI is established based on the instantaneous power theory. Then the average voltage vector in the coordinate system is optimized by the power cost function. Finally, the average voltage vector is used as the modulation signal, and the corresponding switching signal with fixed frequency is generated by the shoot-through segment space vector pulse width modulation (SVPWM) technology. The simulation results show that the ES-qZSI realizes six shoot-through actions per control cycle and achieves the constant frequency control of the system, which verifies the correctness of the proposed control strategy.
Źródło:
Archives of Electrical Engineering; 2022, 71, 1; 21-35
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Network analyses with the use of spatial databases
Autorzy:
Budkowski, Szczepan
Powiązania:
https://bibliotekanauki.pl/articles/2175190.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie
Tematy:
geographic information system
database
network analysis
space management
raster data model
vector data model
system informacji geograficznej
baza danych
gospodarka przestrzenna
analiza sieci
model wektorowy
model rastowy
Opis:
An analysis is the process of browsing and searching for specific information from an entire dataset. The simplest analysis that can be performed on the data is visual analysis. However, it does not provide absolute certainty as to correctness and quality. A more advanced way of selecting required data is computer-based analysis. Analytical operations are performed on the data entered into the computer. The user defines the query, and the program performs calculations and displays the answer on the monitor screen. The aim of this publication is to conduct network analyses with the use of spatial databases. Besides focusing on the analysis as the leading research method, the paper also adopts this method to analyze the literature on the subject. In addition, the paper points to the complementary roles of the raster model and the vector model, emphasizing their coexistence. The paper shows a variety of applications of GIS analyses, from simple buffers around selected areas, through selection, and the intersection of layers, to network analyses. The high degree of advancement of GIS tools allows to build advanced models in which analyses that go beyond the original application of the collected databases can be run.
Źródło:
Geomatics, Landmanagement and Landscape; 2022, 3; 93--102
2300-1496
Pojawia się w:
Geomatics, Landmanagement and Landscape
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Portfolio management of a small RES utility with a structural vector autoregressive model of electricity markets in Germany
Autorzy:
Maciejowska, Katarzyna
Powiązania:
https://bibliotekanauki.pl/articles/2204084.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
intraday electricity market
day-ahead electricity market
structural vector autoregressive model
probabilistic forecasting
trading strategy
Opis:
Electricity producers and traders are exposed to various risks, among which price and volume risk play very important roles. This research considers portfolio-building strategies that enable the proportion of electricity traded in different electricity markets (day-ahead and intraday) to be chosen dynamically. Two types of approaches are considered: a simple strategy, which assumes that these proportions are fixed, and a data-driven strategy, in which the ratios fluctuate. To explore the market information, a structural vector autoregressive model is applied, which allows one to estimate the relationship between the variables of interest and simulate their future distribution. The approach is evaluated using data from the electricity market in Germany. The outcomes indicate that data-driven strategies increase revenue and reduce trading risk. These financial gains may encourage energy traders to apply advanced statistical methods in their portfolio-building process.
Źródło:
Operations Research and Decisions; 2022, 32, 4; 75--90
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
SPATIAL PIGMEAT PRICE TRANSMISSION: THE CASE OF LITHUANIA AND POLAND
PRZESTRZENNA TRANSMISJA CEN MIĘSA WIEPRZOWEGO NA PRZYKŁADZIE LITWY I POLSKI
Autorzy:
Jurkėnaitė, Nelė
Syp, Alina
Powiązania:
https://bibliotekanauki.pl/articles/2130400.pdf
Data publikacji:
2022-03-28
Wydawca:
Instytut Ekonomiki Rolnictwa i Gospodarki Żywnościowej - Państwowy Instytut Badawczy
Tematy:
przestrzenna transmisja cen
rynek mięsa wieprzowego
model autoregresji wektorowej
przyczynowość Grangera
spatial price transmission
pigmeat market
vector autoregression model
Granger causality
Opis:
The paper investigated the patterns of changes in spatial price transmission between pigmeat prices of two post-communist Member States, namely Lithuania and Poland, and five main producing countries in the EU-15, namely Germany, Denmark, France, Spain, and the Netherlands. This study employed vector autoregression modelling, as well as the Granger causality concept, and focused on changes in price behavior from May 2004 to May 2021. The findings suggest fundamental differences in the short-term price behavior of two post-communist countries. Over the investigated period, Poland strengthened the position in the EU pigmeat market and could be classified as a price leading country for the certain markets. The case of Lithuania demonstrated that countries with lower productivity and the dominant share of pig population on small-scale farms as well as high price level became vulnerable and evolved towards a viable national pig farming structures. Hence, a movement of new Member States towards greater market integration must be linked to the spread of innovations in pig farming or exit of uncompetitive farms. In the case of Lithuania, a promising direction of policy implications is support for the establishment of modern and competitive medium-sized farms, as well as the spread of relevant knowledge and innovations.
W pracy zbadano wzorce zmian w przestrzennej transmisji cen mięsa wieprzowego pomiędzy dwoma postkomunistycznymi państwami członkowskimi, tj. Litwą i Polską, a pięcioma głównymi krajami produkującymi w UE-15, tj. Niemcami, Danią, Francją, Hiszpanią i Holandią. W badaniu wykorzystano modelowanie wektorowej autoregresji, a także koncepcję przyczynowości Grangera i skupiono się na zmianach w zachowaniu cen od maja 2004 do maja 2021 roku. Wyniki sugerują fundamentalne różnice w krótkoterminowym zachowaniu cen w dwóch krajach postkomunistycznych. W badanym okresie Polska umocniła pozycję na unijnym rynku mięsa wieprzowego i mogła być zaklasyfikowana jako kraj liderów cenowych na niektórych rynkach. Przypadek Litwy pokazał, że kraje o niższej produktywności i dominującym udziale pogłowia trzody chlewnej w gospodarstwach o małej skali, a także o wysokim poziomie cen stały się wrażliwe i ewoluowały w kierunku opłacalnych krajowych struktur hodowli trzody chlewnej. Dlatego też podążanie nowych państw członkowskich w kierunku większej integracji rynku musi być powiązane z rozprzestrzenianiem się innowacji w hodowli trzody chlewnej lub wyjściem niekonkurencyjnych gospodarstw. W przypadku Litwy obiecującym kierunkiem konsekwencji polityki jest wspieranie tworzenia nowoczesnych i konkurencyjnych gospodarstw średniej wielkości, a także rozpowszechnianie odpowiedniej wiedzy i innowacji.
Źródło:
Zagadnienia Ekonomiki Rolnej; 2022, 370, 1; 87-106
0044-1600
2392-3458
Pojawia się w:
Zagadnienia Ekonomiki Rolnej
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:
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:
Predictive-SVM control method dedicated to an AC/DC converter with an LCL grid filter
Autorzy:
Dmitruk, K.
Powiązania:
https://bibliotekanauki.pl/articles/200760.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
three-phase voltage converter
model predictive control
space vector modulation
infinite control set
Opis:
This paper presents simulation and laboratory test results of an implementation of an infinite control set model predictive control into a three-phase AC/DC converter. The connection between the converter and electric grid is made through an LCL filter, which is characterized by a better reduction of grid current distortions and smaller (cheaper) components in comparison to an L-type filter. On the other hand, this type of filter can cause strong resonance at specific current harmonics, which is efficiently suppressed by the control strategy focusing on the strict control input filter capacitors voltage vector. The presented method links the benefits of using linear control methods based on a space vector modulator and the nonlinear ones, which result in excellent control performance in a steady state as well as in a transient state.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 5; 1049-1056
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
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