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Tytuł:
Cyber-physical test environment for the identification of interacting wear effects in feed axes
Autorzy:
Bott, Alexander
Stöbel, Robin
Osen, Gregor
Fleischer, Jürgen
Powiązania:
https://bibliotekanauki.pl/articles/2200264.pdf
Data publikacji:
2023
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
machine dynamics
wear effect
feed axes
cyber-physical system
Opis:
For a comprehensive optimization and control of production processes, cyber-physical systems are necessary to include machines' time-dependent properties. These wear effects in machine tools, especially the feed axes, can significantly influence the process quality and are a steady research focus. However, the interaction of wear effects between different feed axes has received little attention. Especially models that represent the combined wear influence of different interacting feed axes on the control parameters and machine dynamics hold great potential. To close this knowledge gap, this paper proposes a cyber-physical test environment to identify the interaction of wear effects in feed axes. For this test environment, the relevant boundary conditions of different feed axes in machine tools and their systematic interaction are presented. Through these conditions, a physical test setup is derived and, analogous to this, a virtual model is created. This holistic approach represents the physical and virtual interaction between different components.
Źródło:
Journal of Machine Engineering; 2023, 23, 1; 123--132
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of Automatic Firing System Type Gas-Operated Weapon
Autorzy:
Nguyen, Phon D.
Vo, Bien Van
Nguyen, Phu M.
Tran, Thanh H.
Powiązania:
https://bibliotekanauki.pl/articles/27314927.pdf
Data publikacji:
2023
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
automatic firing system
PKMS machine gun
gas operated weapon
Opis:
The paper presents a new approach to establish a mathematical model of an automatic firing system of gas-operated weapons, which is based on the Lagrange's theory. In contrast to previous studies, a dynamic model is supplemented with dynamic link between a basic mechanism and a receiver assembly with longitudinal clearance without taking into account horizontal clearance. The automatic firing system of the PKMS machine gun has been selected for calculation of a theoretical model and a verification test. Through comparison between theoretical and experimental results, the mathematical model is proven to be accurate and reliable. The results obtained from the paper are the basis for evaluating the automatic firing system ability to work. This is also a reliable source of reference for designers in the process of optimising the structure of the automatic firing system.
Źródło:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2023, 14, 4 (54); 9--22
2081-5891
Pojawia się w:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interrelationship and Determining Factors of Water Quality Dynamics in Whiteleg Shrimp Ponds in Tropical Eco-Green Aquaculture System
Autorzy:
Musa, Muhammad
Mahmudi, Mohammad
Arsad, Sulastri
Lusiana, Evellin Dewi
Sunadji
Wardana, Wisnu Angga
Ompusunggu, Magdalena Florensia
Damayanti, Dhea Novita
Powiązania:
https://bibliotekanauki.pl/articles/2202326.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
aquaculture wastewater
intensive system
Litopenaeus vannamei
mangrove
PCA
principal component analysis
Opis:
Whiteleg shrimp (Litopenaeus vannamei) farming is a major activity in the coastal areas of many tropical countries. To meet the demand in this market, the culture system has expanded using intensive technology, which has resulted in the emission of effluents that threaten the surrounding aquatic ecosystem. Therefore, proper aquaculture management is needed to ensure both economic and ecological benefits. This led to the emergence of eco-green aquaculture. Water quality monitoring is a critical part of aquaculture management and when performed regularly, it yields a large and complex dataset. In this study, the authors aimed to analyse the dynamics of water quality characteristics and the relationships between these variables in whiteleg shrimp ponds in a tropical eco-green aquaculture system from 2020 to 2022. Since the data includes nine parameters and is quite complex, the principal component analysis (PCA) approach was used. This method enables to identify the factors that determine water quality, which will help ensure effective and efficient aquaculture management. Consequently, the water quality variables in the studied area were reduced to five dimensions and salinity, ammonia, and pH were found to be the key factors responsible for the changes in water quality characteristics. Hence, these variables should be the focus of farming management systems.
Źródło:
Journal of Ecological Engineering; 2023, 24, 1; 19--27
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical model of flexible link dynamics in marine tethered systems considering torsion and its influence on tension force
Autorzy:
Trunin, Konstantin
Powiązania:
https://bibliotekanauki.pl/articles/32922104.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
underwater tethered system
flexible links
rigidity
submersible vehicle
Opis:
The rigidity in bending of a flexible link (is an important characteristic that should be considered during regular service conditions. The tension and bending with torsion of wire ropes are also significant factors. This study proposed a method to calculate the vectors of the generalised forces of bending of flexible links. One of the causes of torsional stresses in the power plant of underwater tethered systems is the interaction with ship equipment, such as spiral winding on the winch drum, friction on the flanges of the pulleys or winch drums, and bends on various blocks and rolls that cause torsion. The source of torsional stresses in the FL may also be related to manufacturing, storage, transportation, and its placement on the ship’s winch drums. Torsion can lead to a decrease in the tensile strength due to load redistribution between power elements, or even a violation of their structure. In some cases, torsion significantly affects the movement of the underwater tethered system as a whole. The development of a mathematical model to describe the marine tethered systems dynamics, taking into account the effect of torsion, is important and relevant. The mathematical model of the marine tethered systems dynamics was improved and solved by accounting for the generalised forces of the torsion rigidity of the flexible link, using an algorithm and computer program. The influence of the bending and torsional rigidity of the FL on its deflection and tensile strength were considered based on the example of two problems. The developed program’s working window image shows the simulated parameters and the initial position of the flexible link. The results show that torsion has almost no effect on the shape of the a flexible link’s deflection in the X0Z plane, but leads to a deviation from the X0Z plane when calculating the static deflection of the flexible link. When the carrier vessel is stationary and the submersible vehicle has no restrictions on movement and has positive buoyancy, torsion leads to a three-dimensional change in the shape of the flexible link both in the X0Z plane and in the X0Y plane. The tension force of the flexible link along its length is distributed unevenly, and the torsion of the flexible link can lead to significant changes in its shape, the trajectory of towed objects, and the forces acting on the elements of the marine tethered systems.
Źródło:
Polish Maritime Research; 2023, 2; 188-196
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model‐free sliding mode control for a nonlinear teleoperation system with actuator dynamics
Autorzy:
Abdelwaheb, Henni Mansour
Abderrahmane, Kacimi
AEK, Belaidi
Powiązania:
https://bibliotekanauki.pl/articles/27314234.pdf
Data publikacji:
2023
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
model free sliding mode controller
teleoperation robotic system
actuator dynamics
time-varying delay
model uncertainty
Opis:
Teleoperation robotic systems control, which enables humans to perform activities in remote situations, has become an extremely challenging field in recent decades. In this paper, a Model Free Proportional‐Derivative Slid‐ ing Mode Controller (MFPDSMC) is devoted to the syn‐ chronization problem of teleoperation systems subject to actuator dynamics, time‐varying delay, model uncer‐ tainty, and input interaction forces. For the first time, the teleoperation model used in this study combines actuator dynamics and manipulator models into a single equation, which improves model accuracy and brings it closer to the actual system than in prior studies. Further, the proposed control approach, called Free, involves the simple mea‐ surement of inputs and outputs to enhance the system’s performance without relying on any knowledge from the mathematical model. In addition, our strategy includes a Sliding Mode term with the MFPD term to increase system stability and attain excellent performance against external disturbances. Finally, using the Lyapunov func‐ tion under specified conditions, asymptotic stability is established, and simulation results are compared and provided to demonstrate the efficacy of the proposed strategy.
Źródło:
Journal of Automation Mobile Robotics and Intelligent Systems; 2023, 17, 1; 69--77
1897-8649
2080-2145
Pojawia się w:
Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Motion tracking of a rigid-flexible link robotic system in an underactuated control mode
Autorzy:
Jarzębowska, Elżbieta
Augustynek, Krzysztof
Urbaś, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/27311387.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
manipulator
actuator failure
optimization
computational procedure for constrained dynamics
method CoPCoD
awaria siłownika
optymalizacja
metoda CoPCoD
procedura obliczeniowa dla dynamiki z ograniczeniami
Opis:
The paper presents its contribution to tracking control design of mechanical systems in underactuated mode conditions, i.e. when the number of actuators is less than the number of possible control inputs. Fully actuated mechanical systems are quite well-researched and controller designs are well-developed for them as well. However, due to costs, weight, design, and performance regimes or due to an actuator failure, the underactuated control mode is required in applications. With the aid of the computational procedure for constrained dynamics (CoPCoD), the constrained dynamics, i.e. the reference motion dynamics, and tracking control in an underactuated mode are designed for an example of a three-link planar manipulator model with rigid and flexible links. A dynamic optimization problem is formulated in the paper to obtain optimal time courses of manipulator joint coordinates in underactuated mode conditions in order to apply them to a manipulator driving links controller.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2023, 71, 3; art. no. e144620
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation and improvement of combustor structure in 3D printed sand recycling system
Autorzy:
Gao, Xiao
Lei, Mao
Xu, Weiwei
Powiązania:
https://bibliotekanauki.pl/articles/27315668.pdf
Data publikacji:
2023
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
3D printing
CPFD
Computional Particle Fluid Dynamics
thermal reclamation of used sand
Opis:
In this paper, a new combustor with an output of 5 t/h is designed based on a computational particle fluid dynamics (CPFD) model. The flow field simulation is combined with the combustion simulation to analyze the internal two-phase flow, temperature field, and combustion products. The combustor structure was optimized. The simulation results show that the recovery efficiency of the waste sand and the energy utilization of the combustor can be improved under the original structure. The sand bed has a significant effect on flow field characteristics. The increase in particle temperature in the combustor increases the efficiency of waste sand recovery by increasing the height of the sand bed by 50 mm. The utilization rate of natural gas is increased and the economic efficiency is improved. The feasibility of the CPFD method can simulate the flow field characteristics inside the combustor very effectively.
Źródło:
Polish Journal of Chemical Technology; 2023, 25, 4; 19--27
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on MDO of ship propulsion shafting dynamics considering the coupling effect of a propeller-shafting-hull system
Autorzy:
Liu, Jinlin
Gu, Zheng
Liu, Shuyong
Powiązania:
https://bibliotekanauki.pl/articles/32916294.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship propulsion shafting
dynamic modelling
shafting alignment
shafting vibration
multi-disciplinary design optimisation
Opis:
Dynamic designs for ship propulsion shafting can be categorised as complex multi-disciplinary coupling systems. The traditional single disciplinary optimisation design method has become a bottleneck, restricting the further improvement of shafting design. In this paper, taking a complex propulsion shafting as the object, a dynamic analysis model of the propeller-shafting-hull system was established. In order to analyse the coupling effect of propeller hydrodynamics on shafting dynamics, the propeller’s hydrodynamic force in the wake flow field was calculated as the input for shafting alignment and vibration analysis. On this basis, the discipline decomposition and analysis of the subdisciplines in design of shafting dynamics were carried out. The coupling relationships between design variables in the subdisciplines were studied and the Multi-disciplinary Design Optimisation (MDO) framework of shafting dynamics was established. Finally, taking the hollowness of the shaft segments and the vertical displacement of bearings as design variables, combined with the optimal algorithm, the MDO of shafting dynamics, considering the coupling effect of the propellershafting-hull system, was realised. The results presented in this paper can provide a beneficial reference for improving the design quality of ship shafting.
Źródło:
Polish Maritime Research; 2023, 1; 86-97
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on resilience model of UAV swarm based on complex network dynamics
Autorzy:
Wei, Kunlun
Zhang, Tao
Chuanfu, Zhang
Powiązania:
https://bibliotekanauki.pl/articles/28328275.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
UAV swarm
resilience
SIS
system dynamics
topology
Opis:
Unmanned Aerial Vehicle (UAV) swarms are utilized in various missions and operated within an open environment that is prone to disruptions. The resilience of UAV swarms, an important requirement, mainly revolves around ensuring stable and uninterrupted operations. Malicious attacks can implement the adverse impacts of potential threats through swarm communication links. In this context, the SIS (Susceptible → Infected → Susceptible) method is suitable for describing the information transmission within UAV swarms. An enhanced resilience model of the UAV swarm is proposed in this study, which incorporates the factors of self-dynamics, dynamics of topology, dynamics of information transmission, and SIS into the complex network model. Self-dynamics refer to the internal dynamics of the drones. In this paper, dynamics of topology consist of three factors: the varying distance between drones, the incoming degrees of each drone, and the number of communication types between drones. Lastly, dynamics of information transmission are characterized by SIS. The model proposed in this paper has the capability to effectively capture changes in the network topology as well as the dynamics of the system, which are significant contributors to the loss of resilience. And then, the average number of susceptible drones is utilized as the metric to evaluate the resilience of the swarm. Furthermore, an experiment is conducted where a UAV swarm successfully carries out a surveillance mission to demonstrate the advantages of our proposed method. The proposed model not only enables the support of mission planning but also facilitates the design enhancements of UAV swarms.
Źródło:
Eksploatacja i Niezawodność; 2023, 25, 4; art. no. 173125
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solid Rocket Boosters Separation System Development for the ILR-33 Amber 2K Rocket
Autorzy:
Kierski, Jan
Pazik, Arthur
Cieśliński, Dawid
Powiązania:
https://bibliotekanauki.pl/articles/36828091.pdf
Data publikacji:
2023
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
sounding rocket
solid rocket booster
ILR-33 AMBER 2K
modelling
flight dynamics
ground testing
Opis:
The paper presents the development process of the solid rocket boosters (SRBs) separation system of the ILR-33 AMBER 2K rocket. A redesign of the system was required due to the development of new, larger SRBs. The main system requirements were transmission of forces and moments between the SRBs and the main stage, execution of the separation process at a given moment in flight and mechanical integration simplification. A set of aerodynamics calculations were performed. With the use of computational fluid dynamics software, forces acting on the booster during separation for several angles of attack, as well as the critical booster deflection angle, have been determined. Next, a mathematical model was created to define the load spectrum acting on the system during the flight and separation phases, covering both static and dynamic loads. All the internal and external force sources were considered. A series of motion dynamics simulations were conducted for representative flight cases. Then, the system operational parameters were verified with the use of dedicated ground test facilities. Necessary calibrations of the mathematical model were then implemented, leading to a high level of confidence with the empirical data obtained, thereby leading to a successful system qualification for the flight campaign.
Źródło:
Transactions on Aerospace Research; 2023, 3 (272); 16-27
0509-6669
2545-2835
Pojawia się w:
Transactions on Aerospace Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
System wspomagania oceny stateczności przegubowych wozów wiercących
Support system for articulated drilling rigs stability evaluation
Autorzy:
Bołoz, Łukasz
Powiązania:
https://bibliotekanauki.pl/articles/27323750.pdf
Data publikacji:
2023
Wydawca:
STE GROUP
Tematy:
stateczność wozów wiercących
dynamika wozów wiercących
badania modelowe
model dynamiczny
model fizyczny
model matematyczny
badania symulacyjne
narzędzia CAD/CAE
stability of drilling rigs
drilling rig dynamics
model tests
dynamic model
physical model
mathematical model
simulation tests
CAD/CAE tools
Opis:
Samojezdne maszyny górnicze takie jak kołowo-oponowe wozy wiercące charakteryzują się budową przegubową oraz wyposażone są w wysięgniki z organami roboczymi wysuniętymi daleko poza obrys podwozia. Taka konstrukcja powoduje, że maszyny te są podatne na utratę stateczności. Stąd też konieczne jest analizowanie rozkładu mas oraz ich szeroko pojętej stateczności podczas całego procesu projektowania, przy uwzględnienie wielu czynników wynikających ze sposoby i warunków ich pracy. Jednak brak jest odpowiednich modeli obliczeniowych pozwalających na przeprowadzenie badań analitycznych dla maszyn o takiej konstrukcji. W artykule przedstawiono autorski system wspomagający szybką ocenę stateczności jedno i dwuwysięgnikowych wozów wiercących. Model pozwala na przeprowadzenie analiz bez konieczności rozwiązywania równań różniczkowych występujących w modelach dynamicznych oraz bez stosowania badań modelowych za pomocą narzędzi CAD/CAE. Opracowany model obliczeniowy został zweryfikowany przez porównanie uzyskanych wyników z wynikami z pełnego modelu dynamicznego, z wynikami badań modelowych przeprowadzonych w programie CAD/CAE oraz z wynikami badań empirycznych nacisków kół i podpór na podłoże dla wybranego wozu wiercącego. Na podstawie weryfikacji i walidacji tego modelu stwierdzono jego pełną poprawność oraz przydatność. Model został wykorzystany do opracowania praktycznego i łatwego w obsłudze arkusza obliczeniowego. Następnie przeprowadzono badania analityczne stateczności wybranego wozu wiercącego. Model obliczeniowy jak i arkusz kalkulacyjny stanowią podręczne narzędzie wykorzystywane podczas procesu projektowania przez jedną z polskich firm produkujących wozy wiercące.
Underground mining machines, such as wheel-tyre drilling rigs, are articulated and equipped with booms that project far beyond the undercarriage. Such a structure makes these machines prone to lose stability. Hence, it is necessary to analyse the distribution of masses and geometry as well as their broadly understood stability during the entire design process, taking into account many factors resulting from the manner and conditions of their operation. However, there are no ap-propriate computational models that would enable carrying out analytical tests for machines with this kind of construction. The article presents the author's support system which allows a quick assessment of the stability of single- and twin-boom drilling rigs. The model makes it possible to perform analyses without having to solve differential equations present in dynamic models or using model studies based on CAD/CAE tools. The developed computational model was verified by comparing the obtained results with the results of the full dynamic model, the results of model tests carried out in the CAD/CAE program and the results of empirical tests of wheel and jack pressures on the ground for the selected drilling rig. Based on the verification and validation of this model, it was found to be fully correct and useful. The model was used to prepare a practical and user-friendly calculation sheet. Next, analytical tests of the stability of the selected drilling rig were carried out. The computational model and the spreadsheet provide handy tools used during the design process by one of the Polish companies producing drilling rigs.
Źródło:
Systemy Wspomagania w Inżynierii Produkcji; 2023, 12, 2; 9--27
2391-9361
Pojawia się w:
Systemy Wspomagania w Inżynierii Produkcji
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Alignment of circular economy business models for framing national sustainable economic development
Autorzy:
Atstaja, Dzintra
Cudecka-Purina, Natalija
Hrinchenko, Raisa
Koval, Viktor
Grasis, Janis
Vesere, Rudite
Powiązania:
https://bibliotekanauki.pl/articles/2142872.pdf
Data publikacji:
2022
Wydawca:
Centrum Badań i Innowacji Pro-Akademia
Tematy:
business models
circular economy
system dynamics
sustainability
modele biznesowe
gospodarka o obiegu zamkniętym
dynamika systemów
zrównoważony rozwój
Opis:
Circular economy offers opportunities to boost jobs and tackle climate change. The article reflects aspects of the impact on the environment through sectoral policies to support the circular economy because current business as usual model, based on the linear economy principle leads to a staggering inefficiency in nature resources are managed, with increased pollution, loss of ecosystems and substantial losses of value with each product disposed. This requires a change not only in consumer behaviour but even more on the resource extraction and material production side. The purpose of the research paper is to develop a decision-making matrix providing a step-by-step approach for the policymakers.
Źródło:
Acta Innovations; 2022, 42; 5-14
2300-5599
Pojawia się w:
Acta Innovations
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Beyond the Black Box: Towards a Systems Theory of Farming Family and Family Farm
Poza czarną skrzynkę – w stronę systemowej teorii rodziny rolniczej i jej gospodarstwa
Autorzy:
Pietrzak, Michał
Ziętara, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/2130405.pdf
Data publikacji:
2022-03-28
Wydawca:
Instytut Ekonomiki Rolnictwa i Gospodarki Żywnościowej - Państwowy Instytut Badawczy
Tematy:
rodzinne gospodarstwo rolnicze
myślenie systemowe
dynamika systemów
nowa ekonomia instytucjonalna
family farm
systems thinking
system dynamics
new institutional economics
Opis:
The aim of this article is to present the need for a view of a family farm that is complementary to neoclassical economics and outline the framework concepts on which the future systems theory of family farms could be based. The article is a conceptual overview. The paper presents the development of economics and organization of farms. It was emphasized that in addition to the analytical approach, which today fits into the neoclassical mainstream of economic thought, the organic approach, which is related to the contemporary systems approach, was also important in the discipline. The authors presented two trends considered to be the foundation of the target theory of family farms: systems thinking and new institutional economics. An outline of the concept of a new approach to family farms is presented as a systemic whole connecting the family and its household involved in agricultural production, with the possibility of reducing internal transaction costs (agency costs) being an important attribute of this whole. Family farms still remain the predominant form of agricultural activity in Poland, Europe, and other continents. The family nature of the entities creates their specificity both in terms of goals and behaviors, which is difficult to reduce to the neoclassical model of firm, which seeks to maximize profits. What is needed is a holistic, systems approach complementary to the predominant neoclassical approach, considering close relations between the family and the agricultural production unit.
Celem niniejszego artykułu jest przedstawienie potrzeby komplementarnego względem ekonomii neoklasycznej spojrzenia na rodzinne gospodarstwo rolnicze (RGR), a następnie zarysowanie ramowych koncepcji, na których mogłaby się oprzeć przyszła systemowa teoria RGR. Artykuł ma charakter przeglądowo-koncepcyjny. W tekście dokonano przeglądu rozwoju dyscypliny ekonomiki i organizacji gospodarstw rolniczych. Podkreślono, że oprócz podejścia analitycznego, które obecnie wpisuje się w główny, tj. neoklasyczny nurt myśli ekonomicznej, istotne miejsce w tej dyscyplinie zajmowało podejście organiczne, którego współczesne echa można odnaleźć w podejściu systemowym. Następnie przedstawiono dwa nurty uznane za fundamenty docelowej teorii RGR: myślenie systemowe oraz nową ekonomię instytucjonalną. Przedstawiono zarys koncepcji nowego podejścia do rodzinnego gospodarstwa rolniczego postrzeganego jako systemowa całość łącząca rodzinę i jej gospodarstwo domowe zaangażowane w produkcję rolniczą, przy czym istotnym atrybutem tej całości jest zdolność do redukcji wewnętrznych kosztów transakcyjnych (kosztów agencji). W konkluzji stwierdzono, że gospodarstwa rodzinne wciąż pozostają dominującą formą prowadzenia działalności rolniczej w Polsce, Europie i na innych kontynentach. Rodzinny charakter tych podmiotów tworzy ich specyfikę zarówno na poziomie celów, jak i zachowań, którą trudno zredukować do neoklasycznego modelu maksymalizującej zyski firmy. Potrzebne jest – komplementarne wobec dominującego ujęcia neoklasycznego – podejście holistyczne, systemowe, uwzględniające ścisłe związki między rodziną a rolniczą jednostką produkcyjną.
Źródło:
Zagadnienia Ekonomiki Rolnej; 2022, 370, 1; 42-86
0044-1600
2392-3458
Pojawia się w:
Zagadnienia Ekonomiki Rolnej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of pertinent project delay variables in the Thai construction sector: mathematical analysis
Autorzy:
Ajayi, Babatunde Oluwaseun
Chinda, Thanwadee
Powiązania:
https://bibliotekanauki.pl/articles/2105324.pdf
Data publikacji:
2022
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
construction delay
DEMATEL analysis
system dynamics
preconstruction
project management
poóźnienie budowlane
analiza DEMATEL
dynamika układu
przekonstrukcje
zarządzanie projektem
Opis:
Project completion behind schedule is a struggle for the construction sector, affecting time, cost, and quality. This investigation has been necessitated by the lingering nature of project delay risks despite many extant analyses. This study collated expert opinions from the Thai construction sector on salient construction delay variables and their influence on each other for DEMATEL-SD analysis. The collated data were analysed and found consistent with a Cronbach’s alpha of 0.939. Then, the DEMATEL technique was used to establish the influence weight of factors for the System dynamics (SD) analysis. It was discovered that minimising the design error at the preconstruction stage significantly reduces the magnitude of delay. Increasing values of design error and change order increase the rework profile. Besides, the project delivery within the scheduled 232 weeks can be ensured by minimising the threat of design error, design change, change order, rework, productivity problem, and by improving project management. This study adopted a hybrid mathematical system to holistically examine the construction delay risk by comprehensively exploring the dynamics of influencing variables and investigating their impact on the project scheme. The system helps project stakeholders to arrive at an effective decision in overcoming delay risks, thus minimising the cost overrun and improving the project quality.
Źródło:
Engineering Management in Production and Services; 2022, 14, 2; 26--45
2543-6597
2543-912X
Pojawia się w:
Engineering Management in Production and Services
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Economic assessment of the biological agent use in ecological potato production - system dynamics simulation
Ocena ekonomiczna wykorzystania preparatu biologicznego w ekologicznej produkcji ziemniaka - symulacja dynamiki systemu
Autorzy:
Maciejczak, M.,
Treder, K.,
Urbanowicz, J.,
Osowski, J.,
Olech, I.,
Powiązania:
https://bibliotekanauki.pl/articles/31341439.pdf
Data publikacji:
2022
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Źródło:
Acta Scientiarum Polonorum. Oeconomia; 2022, 21, 4; 13-26
1644-0757
Pojawia się w:
Acta Scientiarum Polonorum. Oeconomia
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 320

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