Temat: heat work - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Thermodynamic Characteristics of Solid
Autorzy:: Pluta, Z.
Hryniewicz, T.
Tematy:: thermodynamic characteristics
interstate space
hermodynamics
solid
potential field
specific proper heat energy
specific gained heat energy
energetic band
heat work
source characteristics of entropy growth
entropy constant; Pokaż więcej
Wydawca:: Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:: https://bibliotekanauki.pl/articles/411946.pdf Link otwiera się w nowym oknie
Opis:: The paper is to present the developed thermodynamic characteristics of a solid. The existent description of dependence of temperature on the proper entropy (thermal capacitance) was used as the beginning point of the considerations. A critical evaluation of the picture of that dependence was a consecutive link of the considerations. Furthermore, an adequate description of the discussed heat phenomenon, taking into account the detailed characteristics of the entropy growth characteristics, has been presented. This characteristics indicates a clear quantum character of the studied reality, reflected by the potentials, proper and gained, respectively. These magnitudes are the measures of the proper and gained specific energies of this thermodynamic factor. The dependence of temperature on the specific energy has been described to formulate a formula on the heat work. At the end the dependence between the specific heat and the entropy constant is derived. In conclusion, a quantum nature of macroscopic reality has been noticed together with the definition of the heat energy notion. The necessity of noticing the description of any other reality in this scale has been indicated.
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Effect of heat exposure on dehydration and kidney function among sea salt workers in Thailand
Autorzy:: Luangwilai, T.
Robson, M.G.
Siriwong, W.
Tematy:: heat exposure
dehydration
kidney function
agricultural work; Pokaż więcej
Wydawca:: Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
Powiązania:: https://bibliotekanauki.pl/articles/2082819.pdf Link otwiera się w nowym oknie
Opis:: Background. Excessive heat exposure and dehydration among agricultural workers have been reported to reduce kidney function and lead to chronic kidney disease of unknown etiology (CKDu). Objective. This cross-sectional study aimed to assess heat exposure, factors related to dehydration and the relationship between dehydration and biomarkers of kidney function among sea salt workers in Thailand. Material and methods. Wet bulb globe temperature (WBGT) was used at the time workers started work outdoors on salt farms. Urine-specific gravity, urine osmolarity, and serum creatinine were collected from 50 workers after work. Results. The results showed that more than 50% of the participants were dehydrated after work. The maximum hours spent working per day was 10. The average water intake was 1.51 L. Urine specific gravity was highly significant correlated with urine osmolality (rs = 0.400, p<0.01), and urine osmolality was significantly correlated with the estimated glomerular filtration rate (eGFR) (rs = 0.349, p<0.05). In bivariate analysis adjusted for age, sex, and current alcohol consumption, we found that a WBGTTWA ≥ 30°C (OR = 0.08, 95% CI = 0.01-0.44, p = 0.003) and hours spent working (OR=2.22, 95% CI = 1.42-3.47, p <0.001) were independently associated with dehydration. This suggests that workers should increase their time spent on breaks and increase water consumption. Conclusions. Educational program on heat exposure and heat-related illness prevention strategies should be provided.
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Investigation of kidney function changes in sea salt workers during harvest season in Thailand
Autorzy:: Luangwilai, T.
Robson, M.G.
Siriwong, W.
Tematy:: heat exposure
agricultural work
kidney function change; Pokaż więcej
Wydawca:: Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
Powiązania:: https://bibliotekanauki.pl/articles/2083100.pdf Link otwiera się w nowym oknie
Opis:: Background. Occupational factors have previously been mentioned as contributing to decreased kidney function and the development of chronic kidney disease of unknown cause. Sea salt workers are one of the occupations facing high outdoor temperatures and a highly, intensive workload. Objective. The purpose of the study was to examine whether the kidney function of sea salt workers at the beginning of the harvest season differs from kidney function at the end of the harvest season and to identify factors that can predict the change of kidney function. Material and methods. Data were collected from salt workers (n=50) who were between 18–60 years of age without hypertension, diabetes, and kidney disease in Samut Sakhon province, Thailand. Urine specific gravity (USG) was used for hydration status and the estimated glomerular filter rate (eGFR) was used to measure kidney function. The mixed model was used to find differences over the harvest season and prediction of factors. Results. On average, the eGFR was estimated to decrease by 15.2 ml/min/1.73 m2 over the harvest season. The decline in eGFR of sea salt workers with moderate and heavy workloads were significantly faster than their light workload counterparts after controlling for other covariates. Similarly, dehydration (USG ≥ 1.030) significantly accelerated the rate of kidney function loss. Conclusions. Our study confirmed exposure to heat over the harvest season leads to decreased eGFR in sea salt workers. The rate of change of eGFR could be predicted by workload and hydration status. Workers with dehydration who performed medium to heavy workloads in farms showed faster kidney function decline than those who performed light workload.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Concept for interpretation and assessment of slide bearings operation in diesel engines in probabilistic approach
Autorzy:: Girtler, J.
Tematy:: friction heat
operation
friction energy
slide bearing
friction work; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/244383.pdf Link otwiera się w nowym oknie
Opis:: The paper provides a proposal of interpretation that valuates operations, which (just like operation of Hamilton and Maupertius shown in the classical mechanics and operation resulting from changes of body momentum) is considered as a physical quantity with: joule-second [joule x second] as a unit of measure. It presents suggestion of a quantitative interpretation of operation of a slide journal bearing, in which energetic interactions proceed at determined time. It has been here motivated that when the suggested interpretation for slide bearing operation in which energy conversions proceed, is accepted the operation can be a carrier of information about states of the systems so, it can become a diagnostic signal. Moreover, an original method of operation analysis and assessment for a slide journal bearing has been herein presented with regards to its reliability and safety. Possibilities of applying this method for the process of taking the rational operating decisions have been shown, too. The homogeneous process of Poison has been applied in order to prove usability of operation in such interpretation. This process has enabled construction of a model of the course of getting-worse operation for a bearing while the operation time goes by. Therefore, the model is a random process of homogenous and independent gains in energy lost due to friction and slide bearing wear.
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Thermodynamic calculation of a rotary engine with external heat supply based on the ideal rallis cycle
Autorzy:: Usenkov, Roman A.
Popov, Igor A.
Gortyshov, Yuri F.
Kokhanova, Svetlana Y.
Latypov, Ravil A.
Tematy:: thermodynamic calculation
ideal cycle
work
heat
external combustion engine; Pokaż więcej
Wydawca:: Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Powiązania:: https://bibliotekanauki.pl/articles/2106207.pdf Link otwiera się w nowym oknie
Opis:: The design and kinematic scheme of the operation of a rotary external combustion engine with offset shafts have been developed. Expressions are obtained that make it possible to calculate the values of the increasing and decreasing functions of the working volume of the hot and cold cavities with a change in the angle of rotation of the rotor. An expression is obtained for calculating the compression ratio in the cold cavity of a rotary heat engine with an external heat supply. An expression has been determined that makes it possible to calculate the total torque of a rotary external combustion engine. A comparative analysis of the torque values of a rotary heat engine with an external heat supply and a Wankel engine is carried out. An assessment of the efficiency of an external combustion engine with offset shafts is carried out. Based on the thermodynamic calculations using ideal Erickson and Rallis cycles for a rotary external combustion engine, the processes occurring inside the hot and cold cavities of a heat engine are described. The thermodynamic condition parameters at the characteristic points of the cycle are determined and expressions are obtained that determine the thermal efficiency of the ideal Erickson and Rallis cycles in relation to the considered external combustion engine. A method for calculating the ideal cycle for an external combustion engine with offset shafts is presented.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Conception of valuation of combustion engine operation
Autorzy:: Girtler, J.
Tematy:: heat
operation
energy
work
semi-Markov process
combustion engine; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/244104.pdf Link otwiera się w nowym oknie
Opis:: The work provides a proposal of interpretation showing operation in terms of values being compared to a physical quantity with the unit of measure called joule-second, just like operations of Hamilton and Maupertius demonstrated in classical mechanics. Operation in this interpretation is also considered in quantum mechanics, referring to body electromagnetic radiation source of which operation is characterized by Planck constant. An original method of analysis and evaluation of machine operation is herein presented in the energetic aspect, as the result of applying the theory of semi-Markov processes. In order to give grounds for usability of such interpreted operation it has been employed the model describing changes in energy of combustion engines, in the form of state-discrete and time-continuous semi-Markov process. The process is thus a semi-Markov model of getting worse combustion engine operation run with the lapse of time and regaining the initial energetic state of the engine after its refurbishment. The limiting distribution of the process has been determined with probabilities of occurring the distinguished energetic states of mentioned engines. The paper shows that the proposed interpretation for the operation enables making a graph of operation, which demonstrates engine operation in the form of field. The attention is paid that the engine operation in the presented version has got the advantage that can be expressed as a quantity with the joule-second as a unit of measure and as a graph in the form of operation field. The coordinate system for presenting the operation as a field, proposed in this paper, refers to the known in thermodynamics possibility of expressing the energy conversion sorts like work and heat (according to the conception of Clapeyron and Belpaire) in the form of fields.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Thermal comfort study of plastics manufacturing industry in converting process
Autorzy:: Sugiono, S.
Novareza, O.
Fardian, R.
Tematy:: thermal comfort
plastics manufacturing industry
converting process
ergonomics
work performance
heat stress
Indonesia; Pokaż więcej
Wydawca:: Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Powiązania:: https://bibliotekanauki.pl/articles/887005.pdf Link otwiera się w nowym oknie
Opis:: Thermal comfort study of plastics manufacturing industry in converting process. Thermal comfort is one of ergonomics factors that can create a significant impact to workers performance. For a better thermal comfort, several environment factors (air temperature, wind speed and relative humidity) should be considered in this research. The object of the study is a building for converting process of plastics manufacturing industry located in Malang, Indonesia. The maximum air temperature inside the building can reach as high as 36°C. The result of this study shows that heat stress is dominantly caused by heat source from machine and wall building. The computational fluid dynamics (CFD) simulation is used to show the air characteristic through inside the building. By using the CFD simulation, some scenarios of solution are successfully presented. Employees thermal comfort was investigated based on predicted mean vote model (PMV) and predicted percentage of dissatisfied model (PPD). Existing condition gives PMV in range from 1.83 to 2.82 and PPD in range from 68.9 to 98%. Meanwhile, modification of ventilation and replacing ceiling material from clear glass into reflective clear glass gave significant impact to reduce PMV into range from 1.63 to 2.18 and PPD into range from 58.2 to 84.2%. In sort, new design converting building process has more comfortable for workers.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Energy, entropy and work function in a molecule with degeneracy
Autorzy:: Malaver, Manuel
Tematy:: Statistical mechanics
degeneracy
entropy
heat capacity
internal energy
limit of high and low temperature
work function; Pokaż więcej
Wydawca:: Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:: https://bibliotekanauki.pl/articles/1177950.pdf Link otwiera się w nowym oknie
Opis:: In this paper, we have deduced some thermodynamic properties for a molecular system with degeneracy based in the postulates of the statistical mechanics. We obtain analytical expressions for internal energy U, heat capacity Cv , entropy S and work function o Helmholtz free energy A. It is predicted in this research the thermodynamic behavior of U, Cv, S and A in the limit of high and low temperature.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Zasady klimatyzacji wyrobisk górniczych kopalń węgla kamiennego w skrajnie trudnych warunkach geotermicznych
Ventilation of excavations in hard coal mines in critical geothermic conditions
Autorzy:: Knechtel, J.
Tematy:: cieplne warunki pracy
klimatyzacja
przepływ ciepła i masy
thermal work conditions
ventilation
flow of heat and mass; Pokaż więcej
Wydawca:: Stowarzyszenie Inżynierów i Techników Górnictwa
Powiązania:: https://bibliotekanauki.pl/articles/166070.pdf Link otwiera się w nowym oknie
Opis:: Zaproponowano metodykę zapewniającą zgodne z przepisami parametry powietrza kopalnianego w wyrobiskach o dużej koncentracji wydobycia, w których panują skrajnie trudne warunki geotermiczne. Przedstawiono zintegrowany system prognozowania, zwalczania i monitorowania zagrożenia klimatycznego dla sieci wyrobisk w głębokiej kopalni węgla kamiennego. Rozważania przeprowadzono w odniesieniu do poziomów, na których temperatura pierwotna skał jest nie tylko wyższa od 40° C, ale również poziomów, na których temperatura ta dochodzi do 50° C. Wymieniony system składa się z kilku modułów, a mianowicie: komputerowej bazy danych dotyczącej badanego obiektu (kopalni, poziomu, partii), zintegrowanej metody prognozowania warunków klimatycznych dla sieci wentylacyjnej w wyrobiskach z opływowymi prądami powietrza oraz w drążonych wyrobiskach z wentylacją odrębną, schematu temperaturowego rozpatrywanej sieci wentylacyjnej. Metodyka obejmuje sposoby efektywnej i ekonomicznej klimatyzacji głębokiego poziomu wydobywczego, przy wykorzystaniu schematu temperaturowego kopalnianej sieci wentylacyjnej, oraz rozwiązania klimatyzacyjne dla wyrobisk z wentylacją odrębną drążonych w skałach o temperaturze pierwotnej dużo wyższej od 40° C, kontrolę skuteczności podjętych środków prewencji zagrożenia klimatycznego oraz wprowadzenie ewentualnej korekty. Przy takim podejściu do problemu możliwe jest zapewnienie prawidłowych warunków klimatycznych w wyrobiskach górniczych o temperaturze pierwotnej skał zbliżonej do 50° C.
This paper presents a methodology which determines the parameters of mining air in highly productive excavations with critical geothermic conditions. An integrated system of forecasting, combating and controlling the climate hazard for excavation network in a deep hard coal mine was presented. The considerations included levels at which the original temperature is higher than 40° C and those whose original temperature comes up to 50° C. The mentioned system consists of the following modules: an electronic database for the tested object (mine, level, lot); an integrated method of forecasting climate conditions for ventilation network which includes excavations with streamlined air currents and excavations with separate ventilation; a temperature scheme of the considered ventilation network; a methodology including an effective and economic ventilation system of the deep output levels by the use of the temperature scheme of the ventilation network; ventilation solutions for excavations with separate ventilation driven in rocks with the original temperature significantly higher than 40° C; the inspection of efficiency of the taken measures for protection from the climate hazard as well as the application of potential corrections. Such an approach may ensure proper climate conditions in mining excavations with the original temperature of rocks approaching 50° C.
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Tempering temperature effects on hardness and impact toughness of 56NiCrMo7 steel
Wpływ temperatury odpuszczania na twardość i udarność stali 56NiCrMo7
Autorzy:: Dąbrowski, R.
Dziurka, R.
Tematy:: stal narzędziowa
obróbka cieplna
mikrostruktura
twardość
udarność
heat treatment
hot work tool steel
microstructure
hardness
impact toughness
fractographic examination; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/354136.pdf Link otwiera się w nowym oknie
Opis:: The assessment of the effect of tempering temperature on hardness and impact toughness of a 56NiCrMo7 grade hot work tool steel was presented in the paper. It has been found that the investigated steel, after quenching in oil from 800°C, softens quite slowly upon tempering within the range between 100 and 675°C, which was confirmed not only by hardness measurements but also by observed changes occurring in its microstructure, whereas the impact energy (KV) absorbed by the test specimen increases with temperature, achieving >66J after tempering at 675°C. The changes observed in the character of the fracture surfaces allows of interpretation of the impact test results for the whole range of tempering temperatures.
W artykule przedstawiono wyniki badań na temat wpływu temperatury odpuszczania na twardość i udarność stali narzędziowej do pracy na gorąco w gatunku 56NiCrMo7. Badania wykonano dla wybranej temperatury austenityzowania równej 800°C. Wykazano, że badana stal zahartowana w oleju od tej temperatury a następnie odpuszczona w zakresie 100-675°C mięknie dość wolno, co potwierdziły nie tylko wyniki pomiarów twardości ale również obserwacje zmian zachodzących w jej mikrostrukturze. Praca złamania (KV) próbki udarnościowej rośnie ze wzrostem temperatury odpuszczania, przekraczając 66 J po odpuszczaniu w 675°C. Potwierdzeniem uzyskanych wyników badan udarności są zmiany zaobserwowane w charakterze przełomów próbek w całym zakresie temperatur odpuszczania.
Dostawca treści:: Biblioteka Nauki

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