Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "high temperature" wg kryterium: Wszystkie pola

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 62
Tytuł:
Behaviour of cement concrete at high temperature
Autorzy:
Hager, I.
Powiązania:
https://bibliotekanauki.pl/articles/201988.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
concrete
high temperature
fire damage
thermal strain
transient thermal strain
hot tested mechanical properties
residual properties
Opis:
The paper presents the impact of high temperature on cement concrete. The presented data have been selected both from the author’s most recent research and the published literature in order to provide a brief outline of the subject. The effect of a high temperature on concrete covers changes taking place in cement paste, aggregates, as well as the interaction of these two constituents, that result in changes of mechanical and physical characteristics of concrete. This paper presents the effects of a high temperature on selected physical properties of concrete, including colour change, thermal strain, thermal strains under load, and transient thermal strains. In addition, changes to mechanical properties are discussed: stress-strain relationship, compressive strength, and modulus of elasticity. Moreover, the phenomenon of explosive spalling and the main factors that affect its extent are analysed in light of the most recent research.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 1; 145-154
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Convective drying of wood chips at high temperature
Autorzy:
Boszko, M.
Malczewski, J.
Grabarczyk, R.
Powiązania:
https://bibliotekanauki.pl/articles/335486.pdf
Data publikacji:
2007
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Maszyn Rolniczych
Tematy:
suszenie konwekcyjne
wióry drewniane
wysoka temperatura
convective drying
wood chips
high temperature
Opis:
Drying of wood chips of the average size 15x5x2 mm and the initial moisture content 50% w.b. was experimentally studied. The drying medium was hot air at the inlet temperature of 500°C, that is well above the ignition temperature of dry wood (approx. 300°C). The experiments were carried out in an electrically heated stove equipped with a device to mix and move wood chips samples. No significant change in the surface colour of wood chips was observed. Drawing conclusions from the experimental result, industrial - scale drying of wood chips in a rotary dryers or similar ones at 500°C inlet temperature of drying air can be envisaged.
Źródło:
Journal of Research and Applications in Agricultural Engineering; 2007, 52, 2; 61-62
1642-686X
2719-423X
Pojawia się w:
Journal of Research and Applications in Agricultural Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High temperature-regulated expression of microRNAs in barley
Autorzy:
Kruszka, K.
Swida-Barteczka, A.
Pacak, A.
Karlowski, W.
Jarmolowski, A.
Szweykowska-Kulinska, Z.
Powiązania:
https://bibliotekanauki.pl/articles/80830.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
small RNA
microRNA
gene expression
high temperature
barley
biogenesis
stress condition
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 3
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High temperature corrosion of metallic materials in coal fired power plant boilers
Autorzy:
Dudziak, T.
Powiązania:
https://bibliotekanauki.pl/articles/391624.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Odlewnictwa
Tematy:
steam oxidation
high temperature
austenitic steel
Ni based alloy
Opis:
The aim of this work was to perform high temperature tests in steam conditions at 700‒800°C for 3000 hours. In this work seven alloys were studied: Cr rich austenitic steels 309S, 310S, HR3C, and two solid-solution strengthened Ni based alloys; Haynes® 230®, 617 alloy and two (γ’) gamma-prime strengthened Ni based alloys; 263 and Haynes® 282®. The obtained results suggest that the exposed materials show high corrosion resistance under steam oxidation conditions where predominantly Cr2O3 and MnCr2O4 compounds developed. The materials showed no chromia evaporation process and no exfoliation of the external oxide scale. However, two (γ’) gamma-prime strengthened Ni based alloys showed a high degree of internal oxidation that increased with temperature.
Źródło:
Prace Instytutu Odlewnictwa; 2017, 57, 4; 277-291
1899-2439
Pojawia się w:
Prace Instytutu Odlewnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Properties of the Inconel 713 Alloy Within the High Temperature Brittleness Range
Autorzy:
Łyczkowska, K.
Adamiec, J.
Jachym, R.
Kwieciński, K.
Powiązania:
https://bibliotekanauki.pl/articles/379589.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
thermal test
mechanical test
Inconel 713C
Gleeble simulation
high temperature
brittleness range
badanie termiczne
badanie mechaniczne
symulacja Gleeble
wysoka temperatura
zakres kruchości
Opis:
Nickel-based alloys are widely used in industries such as the aircraft industry, chemicals, power generation, and others. Their stable mechanical properties in combination with high resistance to aggressive environments at high temperatures make these materials suitable for the production of components of devices and machines intended for operation in extremely difficult conditions, e.g. in aircraft engines. This paper presents the results of thermal and mechanical tests performed on precision castings made of the Inconel 713C alloy and intended for use in the production of low pressure turbine blades. The tests enabled the determination of the nil strength temperature (NST), the nil ductility temperature (NDT), and the ductility recovery temperature (DRT) of the material tested. Based on the values obtained, the high temperature brittleness range (HTBR) and the hot cracking resistance index were determined. Metallographic examinations were conducted in order to describe the cracking mechanisms. It was found that the main cracking mechanism was the partial melting of grains and subsequently the rupture of a thin liquid film along crystal boundaries as a result of deformation during crystallisation. Another cracking mechanism identified was the DDC (Ductility Dip Cracking) mechanism. The results obtained provide a basis for improving precision casting processes for aircraft components and constitute guidelines for designers, engineers, and casting technologists.
Źródło:
Archives of Foundry Engineering; 2017, 17, 4; 103-108
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis in Commutation of a New High Voltage Thyristor Structure for High Temperature
Autorzy:
Toulon, G.
Bourennane, A
Isoird, K
Powiązania:
https://bibliotekanauki.pl/articles/397791.pdf
Data publikacji:
2013
Wydawca:
Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki
Tematy:
zasilanie impulsowe
tyrystor wysokonapięciowy
symulacja TCAD
wysoka temperatura
styk Schottky’ego
pulsed power
high voltage thyristor
TCAD simulations
high temperature
Schottky contacts
Opis:
In this paper, a high voltage thyristor structure using Schottky contacts on the anode side is analysed through 2D physical simulations in terms of switching performance. The replacement of the P emitter of a conventional symmetrical thyristor by a judicious association of P diffusions and Schottky contacts at the anode side contributes to the reduction of the leakage current in the forward direction and hence improves the forward blocking voltage at high temperature while maintaining its reverse blocking capability. It is shown by comparing this structure with a conventional thyristor, that the presence of Schottky contact does not degrade the turn-on process. It is also shown that the presence of Schottky contact reduces the device turn-off time, improving the maximum operating frequency of the device.
Źródło:
International Journal of Microelectronics and Computer Science; 2013, 4, 2; 49-54
2080-8755
2353-9607
Pojawia się w:
International Journal of Microelectronics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wirelessly Powered High-Temperature Strain Measuring Probe Based on Piezoresistive Nanocrystalline Diamond Layers
Autorzy:
Bouřa, A.
Kulha, P.
Husák, M.
Powiązania:
https://bibliotekanauki.pl/articles/220924.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nano-crystalline diamond
strain sensor
high temperature
remote sensing
wireless powering
Opis:
A high-temperature piezo-resistive nano-crystalline diamond strain sensor and wireless powering are presented in this paper. High-temperature sensors and electronic devices are required in harsh environments where the use of conventional electronic circuits is impractical or impossible. Piezo-resistive sensors based on nano-crystalline diamond layers were successfully designed, fabricated and tested. The fabricated sensors are able to operate at temperatures of up to 250°C with a reasonable sensitivity. The basic principles and applicability of wireless powering using the near magnetic field are also presented. The system is intended mainly for circuits demanding energy consumption, such as resistive sensors or devices that consist of discrete components. The paper is focused on the practical aspect and implementation of the wireless powering. The presented equations enable to fit the frequency to the optimal range and to maximize the energy and voltage transfer with respect to the coils’ properties, expected load and given geometry. The developed system uses both high-temperature active devices based on CMOS-SOI technology and strain sensors which can be wirelessly powered from a distance of up to several centimetres with the power consumption reaching hundreds of milliwatts at 200°C. The theoretical calculations are based on the general circuit theory and were performed in the software package Maple. The results were simulated in the Spice software and verified on a real sample of the measuring probe.
Źródło:
Metrology and Measurement Systems; 2016, 23, 3; 437-449
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High temperature versus geomechanical parameters of selected rocks – the present state of research
Autorzy:
Sygała, A.
Bukowska, M.
Janoszek, T.
Powiązania:
https://bibliotekanauki.pl/articles/92117.pdf
Data publikacji:
2013
Wydawca:
Główny Instytut Górnictwa
Tematy:
high temperature
geomechanical parameters
rock
stress-strain characteristics
compressive strength
Young's modulus
wysoka temperatura
parametry geomechaniczne
skała
charakterystyka naprężeniowo-odkształceniowa
odporność na ściskanie
moduł Younga
Opis:
This paper presents the current state of knowledge concerning the examination of the impact of increased temperatures on changes of geomechanical properties of rocks. Based on historical data, the shape of stress-strain characteristics that illustrate the process of the destruction of rock samples as a result of load impact under uniaxial compression in a testing machine, were discussed. The results from the studies on changes in the basic strength and elasticity parameters of rocks, such as the compressive strength and Young’s modulus were compared. On their basis, it was found that temperature has a significant effect on the change of geomechanical properties of rocks. The nature of these changes also depends on other factors (apart from temperature). They are, among others: the mineral composition of rock, the porosity and density. The research analysis showed that changes in the rock by heating it at various temperatures and then uniaxially loading it in a testing machine, are different for different rock types. Most of the important processes that cause changes in the values of the strength parameters of the examined rocks occured in the temperature range of 400 to 600C.
Źródło:
Journal of Sustainable Mining; 2013, 12, 4; 45-51
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High temperature extrusion of pinto bean [Phaseolus vulgaris] and field pea [Pisum sativum] flours
Autorzy:
Gujska, E.
Czarnecki, Z.
Khan, K.
Powiązania:
https://bibliotekanauki.pl/articles/1372659.pdf
Data publikacji:
1996
Wydawca:
Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk w Olsztynie
Tematy:
food product
flour
high temperature
extrudate quality
pinto bean
food technology
Phaseolus vulgaris
Pisum sativum
field pea
extrusion
Opis:
Different flour types (whole, dehulled and high starch fraction) of pinto bean and field pea were extrusion-cooked in a Wenger TX-52 twin screw extruder. The temperature and moisture level were changed during the extrusion process to obtain the best quality extruded products. The extrudates were analysed for expansion, texture, ultrastructure and some functional properties. Our experiments showed that the quality of the extruded products depends upon the conditions of operation of the extruder and the raw material used. The highest expansion indices were noted for both pinto bean and field pea high starch fractions. Also samples from dehulled and whole field pea flour showed very good puffing properties compared to extrudates from corn meal and high starch fractions. Although there were no significant differences in expansion between whole seeds and dehulled flour of pinto bean, differences in density and stress were noted. Stress values of field pea were lower than pinto bean and corresponded very well (inversely) with expansion and density. Scanning electron microscopy showed differences in ultrastructures of extrudates depending on type of flour and extrusion conditions.
Trzy rodzaje mąk (całe ziarno, częściowo obłuszczone oraz frakcja wysoko skrobiowa) z fasoli (Phaseolus vulgaňs) i zielonego grochu (Pisum sativum) (tab.1) poddano procesowi ekstruzji (HTST) przy użyciu ekstrudera o podwójnym ślimaku typu Wenger TX-52. Parametry ekstruzji tj. temperturę i wilgotność surowca zmieniano w czasie trwania procesu. Badano fizyko-chemiczne i funkcjonalne właściwości ekstrudatów. Najwyższym współczynnikiem ekspansji charakteryzowały się produkty otrzymane z frakcji bogatych w skrobię zarówno z fasoli jak i zielonego grochu (tab. 2, 3). Również ekstrudaty z całych i częściowo obłuszczonych ziaren zielonego grochu wyróżniały się bardzo dobrą ekspansją porównywalną z chrupkami otrzymanymi z grysu kukurydzianego. Wyniki analiz siły cięcia świadczącej o kruchości produktu były znacznie niższe dla ekstrudatów z zielonego grochu niż różnych mąk fasoli. Analiza mikroskopowa wykazała różną strukturę uzyskanych ekstrudatów w zależności od rodzaju surowca i parametrów procesu ekstruzji (rys. 1).
Źródło:
Polish Journal of Food and Nutrition Sciences; 1996, 05, 2; 51-60
1230-0322
2083-6007
Pojawia się w:
Polish Journal of Food and Nutrition Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anti-Seismic Behavior of Welded Box Section Column Considering Welding Residual Stress at High Temperature
Autorzy:
Fu, Yadi
Dai, Xueyu
Zhang, Huidi
Wang, Yimin
Powiązania:
https://bibliotekanauki.pl/articles/2203725.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
box section
high temperature
residual stress
hysteretic behavior
Opis:
To study the anti-seismic performance of steel structure under high temperature, the finite element analysis software ABAQUS was used to study the seismic performance of Q235 steel welded box section column at service stage under normal temperature and high temperature fire. The effects of welding residual stress, slenderness ratio, width thickness ratio and axial load level on the hysteretic behavior of columns were analyzed and the stable bearing capacity and hysteretic performance of the column under high temperature were investigated. The results show that the maximum bearing capacity of the column decreases with the increase of the residual stress peak value. With the increase of temperature, a decrease in the maximum bearing capacity of columns under constant axial force and horizontal cyclic load and an increase in the ductility occur.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 1; 5--13
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of unsteady boiling during high-temperatured body dipping in water
Autorzy:
Badur, J.
Bryk, M.
Powiązania:
https://bibliotekanauki.pl/articles/175170.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
boiling
high temperature
fluid
Opis:
In this paper, the analysis of sudden water phase change during high-temperature metal body dipping is presented. According to that purpose, the computational fluid dynamic analysis has been carried out. The nonstationarity and behavior of sudden water phase change has been examined. The calculation model consists of the solid domain (vessel and high-temperature metal) and fluid domain (liquid filling vessel). The metal body insertion to the fluid domain was obtained by the use of dynamic mesh. Special case of the dipping velocity, the metal body of temperature 723 K and fluid temperature 288 K. was examined. Moving on to calculations, the model containing basic conservation equation, expanded of turbulence and liquid evaporation equations has been used.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2017, 138; 75-88
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In-situ Observation of High-Temperature Fracture Behaviour of 347 Stainless Steel Subjected to Simulated Welding Process
Autorzy:
Ko, Seok-Woo
Park, Hyeonwoo
Yoo, Il
Kim, Hansoo
Lee, Joonho
Hwang, Byoungchul
Powiązania:
https://bibliotekanauki.pl/articles/2048885.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
347 stainless steel
in-situ
high temperature
fracture behavior
welding
confocal laser scanning microscope
CLSM
Opis:
In-situ study on the high-temperature fracture behaviour of 347 stainless steel was carried out by using a confocal laser scanning microscope (CLSM). The welding microstructures of the 347 stainless steel were simulated by subjecting the steel specimen to solution and aging treatments. Undissolved NbC carbides were present within grains after solution treatment, and M23C6 carbides were preferentially formed at grain boundaries after subsequent aging treatment. The M23C6 carbides formed at grain boundaries worked as stress concentration sites and thus generated larger cracks during high-temperature tensile testing. In addition, grain boundary embrittlement was found to be a dominant mechanism for the high-temperature fracture of the 347 stainless steel because vacancy diffusion in the Cr-depleted zones enhances intergranular fracture due to the precipitation of M23C6 carbides at grain boundaries.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 4; 1019-1022
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cement slurries for sealing high temperature and high reservoir pressure boreholes
Zaczyny cementowe do uszczelniania otworów wiertniczych o wysokich temperaturach i ciśnieniach złożowych
Autorzy:
Rzepka, M.
Kremieniewski, M.
Kędzierski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1835135.pdf
Data publikacji:
2018
Wydawca:
Instytut Nafty i Gazu - Państwowy Instytut Badawczy
Tematy:
cement slurry
cement stone
high temperature
high pressure
cementing
zaczyn cementowy
kamień cementowy
wysoka temperatura
wysokie ciśnienie
cementowanie
Opis:
A number of cement slurries proposed for sealing casing string in boreholes, where dynamic temperatures are in the range range from about 110 to about 150o C and pressures from 45 to 90 MPa, were investigated and analyzed in this article. In developing recipes were guided by the requirements to be met by cement slurry for the cementing of casing in the conditions of the occurrence of very high temperatures and reservoir pressures. Before the application of cement slurry in industrial conditions, the density, viscosity, thickening time, cement setting, free water and compressive strength of cement stone were examined. Developed cement slurries for HPHT conditions in research carried out in the Oil and Gas Institute – National Research Institute, had densities in the range from 1865 to 1890 kg/m3 and after appropriate fluidifying were characterized by good rheological parameters. Thickening times of the developed cement slurries ranged from approx. 4 to approx. 6 ½ hours, and can be successfully adjusted (most effectively with a suitably selected additive of sodium lignosulfonate in an amount of about 0,25÷1%). The initial viscosities of the cement slurries tested in the HPHT consistometer were small (about 10 Bc). The course of changes in the consistency of cement slurries was “rectangular”, and time between the consistency of 30 and 100 Bc was generally short (about 10 minutes or less). Cement stones formed after bonding of developed cement slurries were characterized by extremely high mechanical parameters. After 2 days, compressive strength of most tested samples exceeded 25 MPa, and after 7 days of hydration, the compressive strength was about 35 MPa. The cement slurry recipes presented in the article can be used for sealing casing strings in our country or in Ukraine (where cementation is performed in deep boreholes).
W artykule przedstawiono opis i analizę badań szeregu zaczynów cementowych proponowanych do uszczelniania kolumn rur okładzinowych w otworach wiertniczych, w których występują temperatury dynamiczne w zakresie od około 110°C do około 150°C i ciśnienia od 45 MPa do 90 MPa. Przy opracowywaniu receptur kierowano się wymaganiami, jakie powinien spełniać zaczyn cementowy użyty do cementowania rur okładzinowych w warunkach występowania bardzo wysokich temperatur oraz ciśnień złożowych. Przed zastosowaniem zaczynu cementowego w warunkach przemysłowych zwracano uwagę na jego gęstość, lepkość, czas gęstnienia, wiązanie, filtrację, odstój wody oraz wytrzymałość kamienia cementowego na ściskanie. Opracowane w INiG – PIB zaczyny cementowe do warunków HPHT posiadały gęstości od 1865 kg/m3 do 1890 kg/m3 i po odpowiednim upłynnieniu cechowały się dobrymi parametrami reologicznymi. Czasy gęstnienia zaczynów cementowych wynosiły od około 4 godzin do około 6,5 godziny i można je z powodzeniem regulować (najskuteczniej za pomocą odpowiednio dobranego dodatku lignosulfonianu sodowego w ilości około 0,25÷1%). Lepkości początkowe zaczynów badanych w konsystometrze ciśnieniowym były niewielkie (wynosiły około 10 Bc). Przebieg zmian konsystencji zaczynów cementowych miał charakter „prostokątny”, a czas pomiędzy uzyskaniem konsystencji 30 Bc i 100 Bc był z reguły krótki (około 10 minut lub krócej). Kamienie cementowe powstałe po związaniu opracowanych zaczynów cechowały się niezwykle wysokimi parametrami mechanicznymi. Już po 2 dniach wytrzymałość na ściskanie większości badanych próbek przekraczała 25 MPa, natomiast po 7 dniach hydratacji wynosiła około 35 MPa. Zaprezentowane w artykule receptury zaczynów mogą być zastosowane podczas uszczelniania kolumn rur okładzinowych w naszym kraju lub na obszarze Ukrainy (gdzie mamy do czynienia z wykonywaniem prac cementacyjnych w głębokich otworach wiertniczych).
Źródło:
Nafta-Gaz; 2018, 74, 10; 739-744
0867-8871
Pojawia się w:
Nafta-Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studying the Flexural Behavior of Reinforced Concrete Beams under the Effect of High Temperature: A Finite Element Model
Autorzy:
Al-Baijat, Hamadallah
Alhawamdeh, Mohammad
Khawaldeh, Aya
Powiązania:
https://bibliotekanauki.pl/articles/102512.pdf
Data publikacji:
2019
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
flexural behaviour
reinforced concrete beam
high temperature
fire
finite element model
deflection
zachowanie przy zginaniu
belka żelbetowa
wysoka temperatura
pożar
model elementu skończonego
ugięcie
Opis:
The strength of concrete elements can be greatly affected by elevated temperature as in fires, and so a great concern must be taken regarding its behavior under such condition. In this paper, a finite element model was built up using ABAQUS software to investigate the flexural behavior of reinforced concrete (RC) beams subjected to service load under elevated temperature. The beam was simply supported and was loaded at one-third and two-third of span length. The study consisted of three RC beams models; the first model simulated a control beam specimen at ambient temperature 20 °C, while the other two models demonstrated damaged beams specimens according to two high temperatures 400 °C and 800 °C, respectively. Each RC beam had 2 m span length, 300 mm height and 200 mm width. The steel reinforcement configuration was 3ϕ16 mm (Grade 60) main bars at the positive moment region in the beam bottom, 2ϕ14 mm (Grade 60) secondary bars at the beam top, and ϕ10 mm /150 mm closed stirrups. The model was validated by comparing its results with the theoretical results from ACI code and literature. Several mechanical properties were investigated including concrete compressive strength, modulus of elasticity, and reinforcing steel yielding strength. The test results showed a reduction in the flexural capacity of the RC beams, tested at 400 °C and 800 °C, of 17.6% and 88.2%, respectively, with respect to the control beam. The maximum service load carried by the beam, at one-third and two-third of the span length, decreased by 17.1% and 88.1% for the 400 ℃ and 800 ℃ high temperature, respectively. The results also showed an increase in deflection when the temperature increased due to the loss in stiffness.
Źródło:
Advances in Science and Technology. Research Journal; 2019, 13, 2; 150-156
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The impact of high temperatures on the work of a firefighter in Nomex protective gear
Autorzy:
Dwornik, Tadeusz
Binkowska, Aneta
Powiązania:
https://bibliotekanauki.pl/articles/13925525.pdf
Data publikacji:
2023-09
Wydawca:
Towarzystwo Pomocy Doraźnej
Tematy:
Firefighters
high temperature
hyperthermia
protective gear
Nomex
efficiency
Opis:
INTRODUCTION: For firefighters to respond effectively and safely in challenging situations, their protective gear must offer maximum protection, comfort, and ergonomics. While this gear protects against high temperatures, it can pose risks in other scenarios. Specialised attire safeguards against fires but can be perilous in localised threats, potentially life-threatening. This is associated with increased internal body temperature, causing rapid breathing, elevated heart rate, increased blood flow and pressure, substantial sweating, and loss of essential elements. The study aimed to compare physical stress levels at high and low ambient temperatures and examine the variations in measured parameters. MATERIAL AND METHODS: This study assesses how working in high temperature conditions wearing firefighter gear affects physical and psychological abilities and recovery between tasks. It evaluates participants' well-being before and after the study, years of service, protective gear comfort, fluid intake, alternatives to standard gear, and recovery time. It uses questionnaires and measurements of vital signs (body temperature, weight, blood pressure, oxygen saturation, heart rate) before and after physical exertion. RESULTS: A total of 152 participants participated in this study, with 30 during the winter season and 122 in the summer. The human body releases heat through convection, conduction, radiation, and evaporation. Maintaining normothermia is challenging at high temperatures. In summer, participants' weight increased due to sweating. After exertion, blood pressure diverged significantly, with the summer group showing a notable increase in systolic pressure, which stressed the need for hydration. Blood oxygen levels increased during exertion but normalised after rest. Pulse rates were similar at rest but significantly increased in the summer group after exertion, highlighting the importance of caution and hydration at high temperatures. CONCLUSIONS: Analysis of collected data, including medical assessments and surveys, clearly demonstrates the significant impact of working in high temperature conditions on the vital parameters of the participants. Prolonged heat exposure, primarily due to the insulating properties of specialised gear and resulting thermal discomfort, accelerates fatigue and exhaustion. This, in turn, leads to increased errors, slower responses, and potential health problems. To address this concern, the introduction of lighter uniform options, adjustments to legal regulations, and the inclusion of overheating risks in medical protocols should be considered as preventive measures.
Źródło:
Critical Care Innovations; 2023, 6, 3; 21-36
2545-2533
Pojawia się w:
Critical Care Innovations
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 62

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies