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Tytuł:
A tandem version of the cops and robber game played on products of graphs
Autorzy:
Clarke, Nancy
Nowakowski, Richard
Powiązania:
https://bibliotekanauki.pl/articles/744348.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
game
cop
tandem-win
pursuit
graph
product
Opis:
In this version of the Cops and Robber game, the cops move in tandems, or pairs, such that they are at distance at most one from each other after every move. The problem is to determine, for a given graph G, the minimum number of tandems sufficient to guarantee a win for the cops. We investigate this game on three graph products, the Cartesian, categorical and strong products.
Źródło:
Discussiones Mathematicae Graph Theory; 2005, 25, 3; 241-249
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Assessment of the Experimental Thermoelectric Cooling System Effectiveness
Autorzy:
Gołębiowska, Justyna
Widomski, Marcin K.
Powiązania:
https://bibliotekanauki.pl/articles/2202299.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
COP
numerical modeling
thermoelectric cooling
cooling effectiveness
Opis:
Solid-state thermoelectric elements, such as thermoelectric (TE) modules, can be used as cooling devices. Small-sized TE modules, characterized by: lack of moving parts, no required refrigerants application as well as variable possible installation and operation positions, allow, in several specified cases, achieving the advantage in cooling process over the conventional refrigeration devices. This paper presents the results of the preliminary numerical determination of energetic efficiency of thermoelectric cooling system, applied for cooling a small-scale experimental room. The heat exchangers used in the cooling system consisted of heat sinks and radiators installed on the both sides of the TE module. The numerical assessment included in this paper, based on a 3D model reflecting the experimental room and thermoelectric cooling system, allowed determining the relation between TE module power supply characteristics and cooling effects, as well as time-related temperature distribution inside the modeled experimental room. The commercial modeling software FLUENT, ANSYS 12.0 by ANSYS Inc. was applied in numerical calculations. The results of the performed laboratory studies were used as a basis for model development, required input data, initial and boundary conditions. The results of laboratory tests showed the influence of amperage of power supply on the efficiency of cooling characteristics, as well as distribution of air temperature inside the experimental room. Calibration and validation of the developed model was also based on the results of laboratory experiment. The obtained results of numerical calculations showed the influence of amperage of power supply on efficiency of cooling characteristics as well as distribution of air temperature inside the experimental room.
Źródło:
Journal of Ecological Engineering; 2022, 23, 12; 99--110
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of absorption refrigeration systems by the method of computational experiment design
Autorzy:
Iffa, Ridha Ben
Kairouani, Lakdar
Bouaziz, Nahla
Powiązania:
https://bibliotekanauki.pl/articles/240120.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
absorption
COP
evapo-compression
refrigeration
adsorpcja
technika chłodnicza
Opis:
The objective of this work is to present an energy analysis of different absorption refrigerating systems operating with diverse refrigerants. Also is applied the method of experimental design to optimize configurations proposed by the absorption pairs used and the operating conditions. Both acceptable coefficient of performance and low operating generator temperature are scrutinised. Therefore, a computer program is developed. An investigation of the thermodynamic properties is presented. Results show the coefficient of performance evolution versus respectively the evaporator temperature, temperature of condensation and generator temperature. A particular interest is devoted to the intermediate pressure effect on the performance of different systems. In order to better converge in the selection of the configuration and the refrigerant, which can ensure a high coefficient of performance associated to relatively low operating generator temperature the plan of experiments has been developed, taking in account all parameters influencing the system performance and the function of operating temperature. Results show that the refrigerating machine containing a compressor between the evaporator and the absorber has a coefficient of performance quite acceptable and that it can work at low generator temperature for about 60°C and using the NH3/LiNO3 as refrigerant.
Źródło:
Archives of Thermodynamics; 2019, 40, 1; 85-102
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biodiversity loss: no future for business as usual
Autorzy:
Linsley, Philip
Abdelbadie, Rasha
Abdelbadie, Roba
Powiązania:
https://bibliotekanauki.pl/articles/2195371.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Ekonomiczny w Katowicach
Tematy:
biodiversity
nature loss
COP15
Convention on Biological Diversity
Opis:
There is an urgent need to reverse biodiversity loss as has been identified in a wide range of reports. This short commentary article considers the need for businesses to act on biodiversity and nature loss. In particular, the focus of the article is a statement issued in November 2022 by a number of businesses imploring governments to take action to address biodiversity loss. The businesses are petitioning for government action on the basis that they can only pledge to radically change their business models if there is political certainty in respect of government actions on biodiversity. This commentary considers this November 2022 statement and sets out relevant context for understanding the statement.
Źródło:
Studies in Risk and Sustainable Development; 2023, 397; 1-5
2720-6300
Pojawia się w:
Studies in Risk and Sustainable Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of Pollution Risk Mapping Methods in an Eastern Mediterranean Catchment
Autorzy:
Michalopoulos, D.
Dimitriou, E.
Powiązania:
https://bibliotekanauki.pl/articles/124225.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
vulnerability mapping
pollution risk mapping
groundwater pollution
COP
DRASTIC
Opis:
The protection and preservation of good groundwater quality is of critical importance worldwide, nowadays. Increasing urbanization, economic development and agricultural activities, combined with limited precipitation contribute to the quantitative and qualitative degradation of groundwater resources, especially in the eastern Mediterranean region. For this purpose, a series of actions are implemented including groundwater vulnerability mapping that can depict prone to pollution aquifers which need protection and/or restoration measures. In this study, the efficiency of two well-known methodologies (COP and DRASTIC) for groundwater vulnerability and pollution risk mapping was assessed in the Sperchios river basin. The vulnerability and pollution risk maps of the two methodologies were spatially compared to each other and the observed similarities and differences were discussed and explained. The output of the study shows that in the particular geoenvironmental conditions DRASTIC method performs better than the COP, particularly in the lowland, porous media aquifer.
Źródło:
Journal of Ecological Engineering; 2018, 19, 1; 55-68
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The topic of climate change in Polish media coverage on the example of the 26th UN Climate Change Conference
Autorzy:
Zadrożniak, Daria
Powiązania:
https://bibliotekanauki.pl/articles/23948969.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Warszawski. Wydział Dziennikarstwa, Informacji i Bibliologii
Tematy:
COP26
UN Climate Change Conference
media
climate change
Opis:
Climate change is one of the most critical global issues, engaging not just researchers and activists but also members of the power elite responsible for political decisions. A key annual event for discussing the challenges of climate change is the UN Climate Conference. Its 26th edition, held in Glasgow in 2021, received widespread coverage in both traditional and online media, earning the moniker “last chance summit.” This article presents a study on the media portrayal of the 26th UN Climate Change Conference (COP26). Concept: The research focused on news published during the Conference in three primary TV news broadcasts (“News”, “Events”, “Facts”) and on the main pages of three internet news portals (Interia, Onet, WP). Results: The study found that COP26, while competing for media attention with other significant events (such as protests against anti-abortion laws and the migration crisis on the Polish-Belarusian border), was featured by all surveyed media organizations. Additionally, each TV news outlet, through actions like sending reporters to Glasgow, and each online portal, through initiatives like participating in Greenpeace-organized events, emphasized the conference’s importance.
Źródło:
Studia Medioznawcze; 2023, 4; 122-132
2451-1617
Pojawia się w:
Studia Medioznawcze
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance analysis of multipurpose refrigeration system (MRS) on fishing vessel
Autorzy:
Ust, Y.
Karakurt, A.
Gunes, U.
Powiązania:
https://bibliotekanauki.pl/articles/258796.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
refrigeration cycles
exergy analysis
exergetic performance coefficient
COP
exergy efficiency
Opis:
The use of efficient refrigerator/freezers helps considerably to reduce the amount of the emitted greenhouse gas. A two-circuit refrigerator-freezer cycle (RF) reveals a higher energy saving potential than a conventional cycle with a single loop of serial evaporators, owing to pressure drop in each evaporator during refrigeration operation and low compression ratio. Therefore, several industrial applications and fish storage systems have been utilized by using multipurpose refrigeration cycle. That is why a theoretical performance analysis based on the exergetic performance coefficient, coefficient of performance (COP), exergy efficiency and exergy destruction ratio criteria, has been carried out for a multipurpose refrigeration system by using different refrigerants in serial and parallel operation conditions. The exergetic performance coefficient criterion is defined as the ratio of exergy output to the total exergy destruction rate (or loss rate of availability). According to the results of the study, the refrigerant R32 shows the best performance in terms of exergetic performance coefficient, COP, exergy efficiency, and exergy destruction ratio from among the other refrigerants (R1234yf, R1234ze, R404A, R407C, R410A, R143A and R502). The effects of the condenser, freezerevaporator and refrigerator-evaporator temperatures on the exergetic performance coefficient, COP, exergy efficiency and exergy destruction ratios have been fully analyzed for the refrigerant R32.
Źródło:
Polish Maritime Research; 2016, 2; 48-56
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exergy analysis of operation of two-phase ejector in compression refrigeration systems
Autorzy:
Dudar, A.
Butrymowicz, D.
Śmierciew, K.
Karwacki, J.
Powiązania:
https://bibliotekanauki.pl/articles/240804.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase ejector
compression refrigeration system
COP
exergy
strumienica dwufazowa
egzergia
Opis:
Paper deals with theoretical analysis of possible efficiency increase of compression refrigeration cycles by means of application of a two-phase ejector. Application of the two phase ejector in subcritical refrigeration system as a booster compressor is discussed in the paper. Results of exergy analysis of the system operating with various working fluids for various operating conditions have been shown. Analysis showed possible exergy efficiency increase of refrigeration compression cycle.
Źródło:
Archives of Thermodynamics; 2013, 34, 4; 107-122
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Poland’s Energy Security Strategy
Autorzy:
Samson, Zuzanna
Powiązania:
https://bibliotekanauki.pl/articles/1977422.pdf
Data publikacji:
2019-09-30
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
Polska
national energy security
coal
renewable energy sources
natural gas
LNG
COP24
Opis:
Poland, as one of the European countries experiencing the most significant economic growth in recent years, permanently relies on coal power. There are plenty of reasons behind this condition, however, wanting to become one of the European leaders Poland ought to diversify its energy sources and lower the share of those harmful to the natural environment. Some changes have already been implemented, nevertheless the Polish government is mostly reluctant to diminish the role of coal mines. Moreover, the current actions taken to diversify sources of natural gas imports are dependent on Polish foreign policy and international alliances. The author analyzes changes in the Polish energy security strategy in recent years and compares them with provisions established during COP24. The article analyzes the Polish energy market with the share of individual sources and examines the possibility to increase the share of those alternative to coal in the near future.
Źródło:
Polish Political Science Yearbook; 2019, 3 (48); 489-499
0208-7375
Pojawia się w:
Polish Political Science Yearbook
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method of determining the COP coefficient for a cooling system
Sposób wyznaczenie współczynnika COP dla układu chłodniczego
Autorzy:
Rząsa, Mariusz
Pochwała, Sławomir
Szymaniec, Sławomir
Powiązania:
https://bibliotekanauki.pl/articles/1841357.pdf
Data publikacji:
2020
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
coefficient of performance
cooling system
inverter compressor
współczynnik COP
układ chłodniczy
sprężarka inwertorowa
Opis:
The basic metrological problem analyzed in this article is the experimental determination of the COP coefficient for arefrigerating system working in a stationary cooling chamber. This issue is because manufacturers of chillers provide the value of this coefficient in device technicaldata.In practice, after installing the refrigeration unit, the COP is often lower. The paper presents amethod of balancing cooling energy for a complete refrigeration system.
Podstawowym problemem metrologicznym, który autorzy pragną przedstawić jest eksperymentalne wyznaczenie współczynnika COP dla układu chłodniczego, pracującego w stacjonarnej komorze chłodniczej. Zagadnienie to jest istotne, ponieważ producenci agregatów chłodniczych najczęściej podają współczynnik COP dla agregatu chłodniczego. W praktyce po zamontowaniu agregatu chłodniczego w komorze chłodniczej współczynnik COP jest niejednokrotnie niższy. Trudność z wyznaczeniem współczynnika COP w układzie chłodniczym polega na koniczności zbilansowania mocy chłodniczej dla całego układu wraz z komorą chłodniczą. W pracy przedstawiono sposób bilansowania energii chłodniczej dla kompletnego układu chłodniczego oraz opisano budowę stanowiska do wyznaczania współczynnika COP.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2020, 10, 4; 69-72
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method of determining the COP coefficient for a cooling system
Sposób wyznaczenie współczynnika COP dla układu chłodniczego
Autorzy:
Rząsa, Mariusz
Pochwała, Sławomir
Szymaniec, Sławomir
Powiązania:
https://bibliotekanauki.pl/articles/1841374.pdf
Data publikacji:
2020
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
coefficient of performance
cooling system
inverter compressor
współczynnik COP
układ chłodniczy
sprężarka inwertorowa
Opis:
The basic metrological problem analyzed in this article is the experimental determination of the COP coefficient for arefrigerating system working in a stationary cooling chamber. This issue is because manufacturers of chillers provide the value of this coefficient in device technicaldata.In practice, after installing the refrigeration unit, the COP is often lower. The paper presents amethod of balancing cooling energy for a complete refrigeration system.
Podstawowym problemem metrologicznym, który autorzy pragną przedstawić jest eksperymentalne wyznaczenie współczynnika COP dla układu chłodniczego, pracującego w stacjonarnej komorze chłodniczej. Zagadnienie to jest istotne, ponieważ producenci agregatów chłodniczych najczęściej podają współczynnik COP dla agregatu chłodniczego. W praktyce po zamontowaniu agregatu chłodniczego w komorze chłodniczej współczynnik COP jest niejednokrotnie niższy. Trudność z wyznaczeniem współczynnika COP w układzie chłodniczym polega na koniczności zbilansowania mocy chłodniczej dla całego układu wraz z komorą chłodniczą. W pracy przedstawiono sposób bilansowania energii chłodniczej dla kompletnego układu chłodniczego oraz opisano budowę stanowiska do wyznaczania współczynnika COP.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2020, 10, 4; 69-72
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Capture-Time Extremal Cop-Win Graphs
Autorzy:
Offner, David
Ojakian, Kerry
Powiązania:
https://bibliotekanauki.pl/articles/32224106.pdf
Data publikacji:
2021-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
pursuit-evasion games
cops and robbers
cop-win graphs
capture time
extremal graphs
Opis:
We investigate extremal graphs related to the game of Cops and Robbers. We focus on graphs where a single cop can catch the robber; such graphs are called cop-win. The capture time of a cop-win graph is the minimum number of moves the cop needs to capture the robber. We consider graphs that are extremal with respect to capture time, i.e., their capture time is as large as possible given their order. We give a new characterization of the set of extremal graphs. For our alternative approach we assign a rank to each vertex of a graph, and then study which configurations of ranks are possible. We partially determine which configurations are possible, enough to prove some further extremal results. We leave a full classification as an open question.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 4; 923-948
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Review of mechanical vapour compression refrigeration system part 2: performance challenge
Autorzy:
Mahmood, R. A.
Ali, O. M.
Al-Janabi, A.
Al-Doori, G.
Noor, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/2106451.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
para
układ chłodniczy
współczynnik wydajności
vapour compression
refrigeration system
cycle
coefficient of performance COP
Opis:
Reducing energy consumption and providing high performance for a vapour compression refrigeration system are big challenges that need more attention and investigation. This paper provides an extensive review of experimental and theoretical studies to present the vapour compression refrigeration system and its modifications that can be used to improve system’s performance and reduce its energy consumption. This paper also presents the challenges that can be considered as a gab of research for the future works and investigations. Cooling capacity, refrigerant effect, energy consumption can be improved by using vapour injection technique, natural working fluid, and heat exchanger. Based on the outcome of this paper, vapour injection technique using natural refrigerant such as water can provide ultimate friendly refrigeration system. Future vision for the vapour compression refrigeration system and its new design technique using Computational Fluid Dynamic (CFD) is also considered and presented.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 3; 119--130
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Portable heat pump testing device
Autorzy:
Kłosowiak, R.
Bartoszewicz, J.
Urbaniak, R.
Powiązania:
https://bibliotekanauki.pl/articles/265008.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
heat pump
renewable energy
coefficient of performance (COP)
pompa ciepła
energia odnawialna
współczynnik wydajności
Opis:
The aim of this paper is to present the design and working principle of a portable testing device for heat pumps in the energy recirculation system. The presented test stand can be used for any refrigerating/reverse flow cycle device to calculate the device energy balance. The equipment is made of two portable containers of the capacity of 250 liters to simulate the air heat source and ground heat source with a system of temperature stabilization, compressor heat pump of the coefficient of performance (COP) of = 4.3, a failsafe system and a control and measurement system.
Źródło:
International Journal of Applied Mechanics and Engineering; 2015, 20, 3; 657-662
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of sounds on posture control
Autorzy:
Siedlecka, B.
Sobera, M.
Sikora, A.
Drzewowska, I.
Powiązania:
https://bibliotekanauki.pl/articles/306857.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
sygnał dźwiękowy
kontrola postawy ciała
COP
stabilność
sounds
posture control
healthy adults
stability improvement
Opis:
Purpose: It is still not clear which parameters of sound are the most significant for body reactions and whether the way of sound reception plays a role in body control. The purpose of this study was to determine the influence of frequency, spectrum and loudness of sounds on posture control in healthy women and men. Methods: The study subjects were 29 young adults who were submitted to a 60-second standing test in the bipedal stance on the force platform (AMTI). During the tests, 3 sinusoidal sounds with various timing and 2 musical sounds (guitar and piano) of the frequency 225 Hz, 1000 Hz and 4000 Hz were applied through headphones. The centre of pressure (COP) amplitude was registered. The sway area and COP mean velocity were computed. Results: It was found that high frequency sounds contributed to a significant decrease of sway area values. No significant influence of low frequency sounds on posture control was observed. The influence of the sound spectrum (timbre) on posture control is limited; only the crescendo spectrum improves the body stability in the bipedal stance and not the music spectrum as guitar and piano. The loudness of sound, although extremely high, is not the cause of postural control changing in relation to lower loudness. No effect of gender was found in terms of body stability under different sound conditions. Conclusion. Based on the results, it can be argued that, in general, in a bipedal stance in terms of stability high sound frequency improves posture control, whereas sound spectrum and intensity show a limited impact.
Źródło:
Acta of Bioengineering and Biomechanics; 2015, 17, 3; 95-102
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł

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