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Wyszukujesz frazę "temperatures" wg kryterium: Temat


Tytuł:
Analysis of impact of aeration modifications on strength parameters of concrete under fire conditions
Autorzy:
Ogrodnik, P.
Zegardlo, B.
Tematy:
concrete
fire temperatures
strength
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Wydawca:
Akademia Wojsk Lądowych imienia generała Tadeusza Kościuszki
Powiązania:
https://bibliotekanauki.pl/articles/30147149.pdf  Link otwiera się w nowym oknie
Opis:
Modern dynamically developing building industry poses more and more complex challenges to building materials. Elevated constructions must satisfy a number of requirements including safety, durability and being environmentally friendly. The unfavorable impact of increased temperatures on the work of a construction structure is manifested by the change in the properties of the heated material and the occurrence of deformation, stresses and thermal scratches. These are particularly dangerous phenomena when they occur in elements with limited freedom of linear deformation. The purpose of the research presented in this article was to find a solution for concrete that is both resistant to spalling and characterized by high strength properties after heating. The main thesis put forward by the authors of the article is the assumption that deliberate concrete aeration will allow the introduction of evenly distributed micro air bubbles into its volume, which will constitute a reservoir for increasing the volume of water converting into water vapor as a result of a sudden increase in temperature. The presented schema enabled the assumption that the strength parameters of aerated concrete would decrease slightly in relation to non-aerated concrete, however it would be still possible to use in reinforced concrete constructions. As can be seen from the aforementioned analyzes, aeration modification can be an effective means of designing high temperature resistant concrete.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of potato starch gelatization temperatures determined by different methods
Porównanie temperatury kleikowania skrobi ziemniaczanej oznaczonej różnymi metodami
Autorzy:
Leszczyński, W.
Golachowski, A.
Tematy:
gelatinization temperatures
potato starch
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Wydawca:
Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk w Olsztynie
Powiązania:
https://bibliotekanauki.pl/articles/1399151.pdf  Link otwiera się w nowym oknie
Opis:
The temperatures of potato starch gelatinization were compared using four methods of determination i.e. Brabender's viscograph, rotary viscosimeter, microscopic and conducting methods. The results of gelatinization temperatures detennined by the methods mentioned above were different. They showed correlation in each case excluding when the results of the final temperature were obtained using Brabender's viscograph.
Jest wiele metod oznaczania temperatury kleikowania skrobi opartych na obserwacji zmian różnych właściwości gałeczek i zawiesin skrobi zachodzących podczas ogrzewania z wodą. Niektóre metody wymagają stosowania kosztownej aparatury, inne są pracochłonne lub nieobiektywne, co uniemożliwia stosowanie ich w laboratoriach przemysłowych. Celem pracy było porównanie wyników oznaczeń temperatury kleikowania skrobi ziemniaczanej wykonanych czterema prostymi, zobiektywizowanymi metodami. Zastosowano dwie metody wiskozymetryczne przy użyciu wiskografu Brabendera i wiskozymetru rotacyjnego „Rotovisko RV-3" oraz dwie nowo opracowane metody: mikroskopową i przewodnościową. Zobiektywizowana metoda mikroskopowa polega na automatycznym rejestrowaniu zamku dwułomności gałeczek podczas ogrzewania na podstawie zmian natężenia światła spolaryzowanego, przechodzącego przez gałeczki, a metoda przewodnościowa oparta jest na automatycznym rejestrowaniu zmian przewodnictwa elektrycznego zawiesiny skrobi podczas ogrzewania. Na rys. 1 przedstawiono przyjęte sposoby wyznaczania temperatury kleikowania skrobi. Na podstawie obliczeń statystycznych stwierdzono, że wyniki uzyskane stosowanymi metodami różniły się między sobą (tab. 1). Najwyższe wartości temperatury początkowej i końcowej kleikowania otrzymano przy użyciu wiskografu Brabendera (temp. początkowa średnio 64,1°C, temp. końcowa - 90,5°C), a najniższe przy zastosowaniu metody przewodnościowej (temp. początkowa 57,3°C, temp. końcowa 68,7°q. Wyniki oznaczeń temperatury początkowej kleikowania oznaczone stosowanymi metodami były ze sobą skorelowane, a wartości współczynników korelacji wahały się od 0,926 do 0,990. Natomiast wyniki oznaczeń temperatury końcowej kleikowania wykonane przy zastosowaniu wiskografu Brabendera nie były skorelowane z wynikami otrzymanymi przy użyciu pozostałych metod (tab. 2). Opracowane metody - przewodnościowa i mikroscopowa - mogą być stosowane do oznaczeń temperatury kleikowania. Przemawiają za tym wysokie współczynniki korelacji między wynikami otrzymanymi tymi metodami, a metodami wiskozometrycznymi oraz ich dokładność i stosunkowo mała czasochłonność. Metoda przewodnościowa jest bardziej odpowiednia w przypadku badania większych partii skrobi, a mikroskopowa zwłaszcza wówczas, gdy dysponuje się małymi ilościami materiału do analiz.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Paramagnetic properties of Cuban red mud at low temperatures
Autorzy:
Shvets, V.
Tematy:
iron ores
metals oxides
ESR
low temperatures
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Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Powiązania:
https://bibliotekanauki.pl/articles/184300.pdf  Link otwiera się w nowym oknie
Opis:
The electron spin resonance (ESR) spectra of Cuban red mud have been measured at three different temperatures: 295 K, 150 K and 77 K. The broad absorption line with resonance fields ∼(1.7–1.8) kOe was observed at all temperatures with values of g-factor from 3.602 to 4.020. The temperature decrease resulted in an absorption line appearance with resonance fields of 3.252 kOe (g = 2.067) at 150 K and 3.339 kOe (g = 2.086) at 77 K. The ESR-signal amplitude with resonance fields ∼(1.7–1.8) kOe decreases and the ESR-signal amplitude in the field ∼3.3 kОе increases with reduction in temperature.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fire Resistance of Timber Joints with Steel Fasteners
Autorzy:
Domański, T.
Kmiecik, K.
Tematy:
thermal conductivity
fire safety
connections
elevated temperatures
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Wydawca:
Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/105572.pdf  Link otwiera się w nowym oknie
Opis:
Fire safety is a major concern in the design of timber construction. Wood is combustible material. The thermal response of timber connections is usually the main factor in evaluating the overall load-bearing capacity of wood structures exposed to fire. The analysis of timber joints under fire conditions is difficult and complex. Finite element model is developed to predict the thermal behavior of bolted wood-to-wood joints exposed to fire. In fire, the material characteristic depend on the temperature. The thermal model is continuous, taking into account the thermal continuity between the joint components. Also, the thermal model is used to predict the evolution of the temperature field inside the connection. The paper presents a summary of results from a numerical studies of the fire behavior of wood-to-wood timber connections with steel bolt. As a result of computer simulations the temperature distribution was obtained. During fire exposure, the timber section is reduced and steel bolt reduces strength. Loadcarrying capacity per shear plane in fire conditions was calculated using two methods: design methods according to EN 1995-1-1 [5] and reduced load method according to EN 1995-1-2 [6]. In the first approach, the timber section loss and steel strength reduction during the fire were taken into account.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Repeated Whole-Body Cryotherapy on Blood Thiol Status in Men Depending on Age and Physical Activity
Autorzy:
Wojciak, Gabriela
Szymura, Jadwiga
Szygula, Zbigniew
Gradek, Joanna
Wiecek, Magdalena
Tematy:
GSH
GSSG
cryogenic temperatures
oxidative stress
aging
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Wydawca:
Akademia Wychowania Fizycznego im. Bronisława Czecha w Krakowie
Powiązania:
https://bibliotekanauki.pl/articles/58719298.pdf  Link otwiera się w nowym oknie
Opis:
Introduction: The aging process of society is progressing worldwide. It is associated with an increased incidence of diseases related to old age accompanied by oxidative stress. Glutathione plays a significant antioxidant role in maintaining physiological prooxidative-antioxidant balance. Objectives: The aim of the study is to assess the effects of whole-body cryotherapy (WBC) on blood thiol status of trained and untrained men depending on age. Material and methods: The study involved 20 older and 20 young healthy males. In each group, there were 10 long-distance runners (60RUN, 20RUN) and 10 untrained individuals, creating groups for comparison (60COM and 20COM). The subjects underwent 24 WBC treatments (3 min, -130°C) every other day. Before and after the 1st and following the 12th and 24th WBC treatments, reduced (GSH) and oxidised glutathione (GSSG) were determined in the erythrocytes, and the oxidative stress index (GSH/GSSG) was calculated. Results: After the 1st WBC treatment, there was a significant increase in GSSG concentration for the 60RUN, 20RUN and 20COM groups, as well as a significant decrease in GSH/GSSG for 20COM. After 12 WBC treatments, the concentration of GSH in the 60COM and 20COM groups increased significantly. In contrast, a series of 24 treatments caused a significant increase in the GSH/GSSG ratio for the 60RUN group. Conclusions: A single WBC treatment affects prooxidative-antioxidant balance. Whole-bo dy cryotherapy, used in a series every other day, reduces the level of oxidative stress by increasing the concentration of GSH, especially in older people, regardless of their level of physical activity.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature effects on the seed germination of some perennial and annual species of Asteraceae family
Autorzy:
Zarghani, Hadi
Mijani, Sajad
Nasrabadi, Samieh Eskandari
Ghias-Abadi, Mohhamad
Khorramdel, Surur
Azimi, Reyhaneh
Tematy:
cardinal temperatures
dark germination
life cycle
medicinal species
Pokaż więcej
Wydawca:
Instytut Hodowli i Aklimatyzacji Roślin
Powiązania:
https://bibliotekanauki.pl/articles/55928254.pdf  Link otwiera się w nowym oknie
Opis:
Temperature is the most critical factor determining success or failure of plant establishment. Seed germination response of five medicinal species include three seed-propagated perennial species, Cichorium intybus, cynara scolymus and Echinacea purpurea and vegetative-reproduction perennial species, Achillea millefolium and annual species, Matricaria aurea were assessed at constant temperatures. The seeds were exposed to constant temperatures of 5, 10, 15, 20, 25, 30, 35, 40 and 45°C under total darkness. Germination percentage of all the species were significantly affected by various temperatures (p ≤ 0.001). A. millefolium did not germinate at 5-10 and 35-45°C, but showed noticeable germination percentage (73.3-100%) at temperatures ranged from 15-30° C. The highest total germination percentage was observed within the range of 15-35 °C for other species. Also, we calculated cardinal temperatures (the minimum, optimum and maximum temperature) for seed germination of species. The highest value for minimum temperature was 10.07ºC in A. millefolium followed by C. scolymus and M. aurea (5ºC) while the lowest was for E. purpurea and C. intybus (2.68 and 2.90ºC respectively). The lowest value for optimum temperature was detected in A. millefolium (22.72ºC) and M. aurea (23.88°C) while the maximum values were observed in E. purpurea and C. intybus (30.40ºC and 29.90ºC respectively). Based on results of present study we concluded that species with both vegetative and seed-propagated reproduction forms like A. millefolium had smaller temperature range rather those with just one way of reproduction (seed production).
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Planetary temperatures in the presence of an inert, nonradiative atmosphere
Autorzy:
Nicol, John Leslie
Tematy:
planet
inert atmosphere
temperatures
capacity/conductivity
soil
air
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Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Powiązania:
https://bibliotekanauki.pl/articles/1050896.pdf  Link otwiera się w nowym oknie
Opis:
This study considers solid planets at about 300 K and an inert atmosphere having no interaction with associated radiation. Processes considered include transfer of energy from the surface skin to underlying layers depending on thermal properties. Temperatures of the surface depend on the rates of transfer of energy between soil layers. The atmosphere is warmed at base by contact with the surface, convection and turbulence distributing higher temperatures through the air. Comparisons between theoretical and measured temperatures show a close similarity. Mean planetary temperatures are calculated, depending on thermal parameters and the intensity of light/radiation from the particular solar system.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of Cardinal Temperatures and Thermal Time Requirement for Germination of Scrophularia Striata and Tanacetum Polycephalum (Schultz Bip. Ssp. Heterophyllum)
Autorzy:
Karavani, Bahram
Afshari, Reza Tavakkol
Hosseini, Nasser Majnoon
Moosavi, Seyed Amir
Akbari, Hamed
Tematy:
Cardinal temperatures,
Seed germination rate,
Thermal time,
modeling
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Wydawca:
Instytut Hodowli i Aklimatyzacji Roślin
Powiązania:
https://bibliotekanauki.pl/articles/2199708.pdf  Link otwiera się w nowym oknie
Opis:
Scrophularia striata and Tanacetum polycephalum are important medicinal plants in Iran which are rich inessential oils, bitter substances, and sesquiterpene lactones. The present study was conducted to compare fournon-linear regression models (segmented, beta, beta modified and Dent-like) to describe the germination ratetemperaturerelationships of Scrophularia striata and Tanacetum polycephalum over eight and seven constanttemperatures, respectively, to find cardinal temperatures and thermal time requirements to reach differentgermination percentiles. An iterative optimization method was used to calibrate the models and differentstatistical indices including RMSE, coefficient of determination (R2), and AICc were applied to compare theirperformance. The beta model was found to be the best model to predict germination rate of Scrophulariastriata at D10, D50 and D90 (R2 = 0.96, R2 = 0.97, R2 = 0.95; RMSE = 0.005, 0.001 and 0.001, respectively).According to this model outputs, the base, optimum, and the maximum temperatures for germination wereestimated as 1.21 ± 0.39, 25.91 ± 0.33 and 46.35 ± 4.12 °C, respectively. Also the segmented model wasfound to be the best model to predict germination rate of Tanacetum polycephalum at D10, D50 and D90 (R2= 0.98, R2 = 0.98, R2 = 0.98; RMSE = 0.067, 0.59 and 0.56, respectively). According to the model outputs, thebase, optimum, and the maximum temperatures for germination were estimated as 0.44±1.15, 26.95±0.75 and38.33±0.98 oC, respectively. It seems these two medicinal plants need moderate optimum temperature for seedgermination.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature effects on the seed germination of some perennial and annual species of Asteraceae family
Autorzy:
Zarghani, Hadi
Mijani, Sajad
Nasrabadi, Samieh Eskandari
Ghias-Abadi, Mohhamad
Khorramdel, Surur
Azimi, Reyhaneh
Tematy:
cardinal temperatures
dark germination
life cycle
medicinal species
Pokaż więcej
Wydawca:
Instytut Hodowli i Aklimatyzacji Roślin
Powiązania:
https://bibliotekanauki.pl/articles/2199738.pdf  Link otwiera się w nowym oknie
Opis:
Temperature is the most critical factor determining success or failure of plant establishment. Seed germination response of five medicinal species include three seed-propagated perennial species, Cichorium intybus, cynara scolymus and Echinacea purpurea and vegetative-reproduction perennial species, Achillea millefolium and annual species, Matricaria aurea were assessed at constant temperatures. The seeds were exposed to constant temperatures of 5, 10, 15, 20, 25, 30, 35, 40 and 45°C under total darkness. Germination percentage of all the species were significantly affected by various temperatures (p ≤ 0.001). A. millefolium did not germinate at 5-10 and 35-45°C, but showed noticeable germination percentage (73.3-100%) at temperatures ranged from 15-30° C. The highest total germination percentage was observed within the range of 15-35 °C for other species. Also, we calculated cardinal temperatures (the minimum, optimum and maximum temperature) for seed germination of species. The highest value for minimum temperature was 10.07ºC in A. millefolium followed by C. scolymus and M. aurea (5ºC) while the lowest was for E. purpurea and C. intybus (2.68 and 2.90ºC respectively). The lowest value for optimum temperature was detected in A. millefolium (22.72ºC) and M. aurea (23.88°C) while the maximum values were observed in E. purpurea and C. intybus (30.40ºC and 29.90ºC respectively). Based on results of present study we concluded that species with both vegetative and seed-propagated reproduction forms like A. millefolium had smaller temperature range rather those with just one way of reproduction (seed production).
Dostawca treści:
Biblioteka Nauki
Artykuł

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