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Wyświetlanie 1-10 z 291
Tytuł:
An experimental method for estimating the thermal diffusivity of building elements, depending on the resolution of temperature measurement
Autorzy:
Owczarek, Mariusz
Powiązania:
https://bibliotekanauki.pl/articles/132057.pdf
Data publikacji:
2019
Wydawca:
Centrum Rzeczoznawstwa Budowlanego Sp. z o.o.
Tematy:
thermal diffusivity
physical properties
Opis:
Thermal diffusivity, also known as temperature equalization coefficient, is the basic parameter in the Fourier equation for non-stationary heat exchange. Its values are known for homogeneous materials with a specific composition. Building elements made of reinforced concrete, for example, have a heterogeneous structure. For such cases, table values from the literature may differ significantly from the specific object for in real constructions. More accurate thermal diffusivity values can be obtained from measurements for a given element. Since these are usually large sized elements, the measurement method should take into account the material in the entire volume of the element. Proposals for such a method based solely on temperature measurement at several depths in the sample were presented. It consists in solving the inverse problem assuming a polynomial solution of the Fourier equation. An attempt was made to validate the method through a numerical experiment. Temperature variability was simulated with one-dimensional flow in the wall with assumed thermal diffusivity. Then the value of this diffusivity was determined from the calculated temperatures. On the inside of the partition, a constant temperature was maintained and on the outside it changed periodically. The dependence of the error in the obtained diffusivity value on the precision of temperature results was analyzed. Depending on the precision of the calculations, a minimum relative error of 2 to 6 percent was obtained. With the help of the data presented in the article, conclusions can be drawn as to the conditions that must be met to determine the value of diffusivity in real measurements with the required accuracy. The obtained results indicate that this method is worth further research.
Źródło:
Modern Engineering; 2019, 1; 28-33
2450-5501
Pojawia się w:
Modern Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A movable string sieve - analysis of seed screening
Autorzy:
Kaliniewicz, Z.
Domański, J.
Powiązania:
https://bibliotekanauki.pl/articles/298132.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
string sieve
modeling
physical properties
Opis:
The conditions of seed movement in a string sieve set into reciprocating motion have been formulated for cereal, vetch, pea, lupine and faba bean seeds. In the analyzed string sieve, seed movement was determined by a combination of the following parameters: angular velocity of the crank, crank radius, seed size, seed’s coefficient of external friction, string diameter and angle of inclination of the separator screen. A string sieve for cleaning and sorting most farm-produced seeds was analyzed. The width of the separating groove was set at 1 mm at the beginning of the screen and 11 mm at the end of the screen, and the strings had the diameter of 4 mm. Our results indicate that seeds cannot be effectively graded in the modeled string sieve. The angular velocity of the crank exceeds the velocity which is applied to power conventional separator buckets, and it could damage the separator. A reduction in the angular velocity of the crank to the recommended level caused seeds to become jammed directly before the screening site. The above problem can be solved by propelling seeds into motion with the use of special sweeping brushes.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2013, 16(4); 253-264
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variability in and correlations among selected physical properties of European larch (Larix decidua Mill.) seeds
Autorzy:
Kaliniewicz, Z.
Tylek, P.
Anders, A.
Markowski, P.
Rawa, T.
Powiązania:
https://bibliotekanauki.pl/articles/297835.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
seeds
physical properties
coefficients
correlation
Opis:
Selected physical attributes of European larch seeds harvested from 2 seed plantations and 2 commercial seed stands in north-eastern Poland were determined. The physical properties of seeds were measured, and the results were used to calculate indicators of seed weight and the frictional and geometric properties of seeds. Physical attributes and indicators were compared by Student’s t-test for independent samples, analysis of variance, correlation analysis and linear regression analysis. The average values of physical properties and indicators were determined at: critical transport velocity - from 5.93 to 6.13 m • s-1, thickness - from 1.25 to 1.43 mm, width - from 2.29 to 2.71 mm, length - from 3.71 to 4.57 mm, angle of sliding friction - from 27.85 to 31.98o, weight - from 4.03 to 6.14 mg, coefficient of sliding friction - from 0.54 to 0.63, arithmetic mean diameter - from 2.42 to 2.90 mm, geometric mean diameter - from 2.20 to 2.60 mm, aspect ratio - from 59.60 to 62.38%, sphericity index - from 57.27 to 59.40%, specific weight - from 1.81 to 2.33 g • m-1, volume - from 4.60 to 7.59 mm3 and density - from 0.82 to 0.91 g • cm-3. The material harvested in seed plantations differed from seeds from commercial seed stands in all parameters, excluding critical transport velocity. Seed weight was most correlated with the remaining parameters. The highest value of the correlation coefficient and the equation with the highest value of the coefficient of determination were reported for the dependence between seed weight and seed length. Seed weight was also relatively highly correlated with seed width, therefore, the use of mesh screens with round openings and/or cylindrical grain graders is recommended in seed sorting processes.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2014, 17(2); 123-134
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of starch content on selected properties of hardboard
Autorzy:
Wronka, Anita
Rdest, Adam
Kowaluk, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/2200220.pdf
Data publikacji:
2020
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
potato starch
fiberboard
mechanical properties
physical properties
Opis:
Influence of starch content on selected properties of hardboard. The aim of the research was to examine the possibility of producing wet-formed fiberboard using a different content of potato starch. The scope of works included the production of plates in laboratory conditions with 0, 1, 5, 10 and 20% mass content of potato starch and subjecting them to selected physical and mechanical tests. Thanks to the research, it was possible to produce a hard fiberboard hardboard using a mass fraction of starch. The results of the tests confirmed that as the starch content in the panel increases, the value of mechanical properties increases also.
Wpływ udziału skrobi na wybrane właściwości płyt pilśniowych mokroformowanych. Celem badań było określenie możliwości produkcji płyt pilśniowych twardych (mokroformowanych) z wykorzystaniem różnego udziału skrobi ziemniaczanej, jako środka wzmacniającego. Zakres prac obejmował wytworzenie płyt w warunkach laboratoryjnych przy: 0, 1, 5, 10, 20% udziale masowym skrobi ziemniaczanej oraz poddanie ich wybranym próbom fizycznym i mechanicznym. Potwierdzono możliwość wytwarzania płyt pilśniowych twardych z wykorzystaniem skrobi.
Źródło:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology; 2020, 109; 48--52
1898-5912
Pojawia się w:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wood plastic composites as a substitution for HDF
Autorzy:
Borysiuk, Piotr
Auriga, Radosław
Powiązania:
https://bibliotekanauki.pl/articles/2171758.pdf
Data publikacji:
2022
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
WPC
composites
PLA
mechanical properties
physical properties
Opis:
Wood plastic composites as a substitution for HDF. As part of the research, industrial HDF boards were used and WPC composites were produced, differentiated in terms of matrix (PLA and HDPE) and filler content (40%, 50% and 60%). The density and density profile was measured to compare HDF and WPC structure. In addition, the manufactured boards were tested for strength (MOR, MOE), screw holding, thickness swelling and water absorption after immersion in water for 2 and 24 hours. WPC were characterized by a higher density than HDF boards and a uniform density profile. In addition, WPC composites were characterized by lower MOR and MOE values than HDF boards. Compared to HDF boards, WPC composites were characterized by higher values of screw holding and better resistance to moisture.
Kompozyty WPC jako substytut płyt HDF. W ramach badań wykorzystano przemysłowe płyty HDF oraz wytworzono kompozyty WPC zróżnicowane pod kątem matrycy (PLA i HDPE) oraz udziału napełniacza (40%, 50% i 60%). Oznaczono gęstość i profil gęstości w celu porównania struktury HDF i WPC. Ponadto wytworzone płyty zostały przetestowane pod kątem wytrzymałości (MOR, MOE), utrzymania wkrętów, spęcznienia na grubość oraz nasiąkliwości po moczeniu w wodzie przez 2 i 24 godziny. WPC charakteryzowały się wyższa gęstością niż płyty HDF oraz jednorodnym profilem gęstości. Ponadto kompozyty WPC charakteryzowały się niższymi wartościami MOR i MOE niż płyty HDF. W porównaniu do płyt HDF kompozyty WPC charakteryzowały się wyższymi wartościami zdolności utrzymania wkrętów oraz lepszą odpornością na działanie wilgoci.
Źródło:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology; 2022, 119; 84--93
1898-5912
Pojawia się w:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interrelations between selected physical and technological properties of wheat grain
Autorzy:
Warechowska, M.
Warechowski, J.
Markowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/298001.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
wheat
grain
physical properties
technological properties
geometrical properties
Opis:
The aim of this work was to determine selected physical properties of wheat grain which are of significance in transport, separation and storage processes as well as to assess the correlations between them and the technological properties of wheat. The grain of two wheat varieties (Eta and Banti) which are popular in Poland was used as research material. The tested properties included: vitreousness, test weight, thousand kernel weight, true density, geometric parameters (thickness, width, length), static friction coefficient of wheat kernels against steel and glass, protein and gluten content and the Zeleny sedimentation value. The grain of the investigated wheat varieties differed in most physical and technological properties. The average length, width and thickness kernels were 6.31 mm, 3.31 mm and 3.03 mm for vr. Banti and 6.05 mm, 3.33 mm, 2.97 mm for vr. Eta. The test weight ranged from 75.68 (Banti) to 78.29 kg • hl-1 (Eta), the thousand kernel weight from 36.3 (Eta) to 39.2 g (Banti) and vitreousness was from 13 (Banti) to 81% (Eta). A correlation between the physical and technological properties of wheat was found. The vitreousness of the wheat grain was positively correlated with protein content (the correlation indices were 0.58 for Banti variety and 0.67 for Eta) and the volume was positively correlated with the true density of grain (r = -0.69 Eta, r = -0.64 Banti). The static coefficient of the friction of wheat grains of two structural materials (metal or glass) is insufficient to predict its technological properties.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2013, 16(4); 281-290
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlations between basic physical parameters of nuts and the weight of common beech (Fagus sylvatica L.) seeds
Autorzy:
Kaliniewicz, Z.
Tylek, P.
Anders, A.
Markowski, P.
Rawa, T.
Andros, K.
Powiązania:
https://bibliotekanauki.pl/articles/297912.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
nuts
seeds
physical properties
variation
correlation
Opis:
Selected physical attributes of common beech nuts harvested from four tree stands in northern Poland were determined. Seeds were manually extracted from every nut. Seeds and nuts were weighed, and the results were used to determine the ratio of seed weight to nut weight, which described the degree of nut filling. Physical parameters and the calculated coefficients were compared by the t-test for independent samples, analysis of variance, correlation analysis and linear regression analysis. The following ranges of variation were reported in the physical attributes of nuts and the coefficients of common beech seeds: critical transport velocity of nuts - from 6.33 to 11.28 m s-1, nut thickness - from 4.76 to 9.86 mm, nut width - from 6.46 to 13.54 mm, nut length - from 12.63 to 21.62 mm, angle of sliding friction of nuts - from 15.67 to 26.67o, nut weight - from 93.0 to 513.7 mg, coefficient of sliding friction of nuts - from 0.28 to 0.50, seed weight - from 11.0 to 374.8 mg, and ratio of seed weight to nut weight - from 0.08 to 0.88. The majority of nuts contained one seed (average weight of 195.36 mg), and only 2.3% of nuts contained two seeds (average weight of 103.11 mg). The attribute that was most highly correlated with the ratio of seed weight to nut weight was seed weight (0.685), followed by critical transport velocity (0.527) and weight of nuts (0.493). The results indicate that common beech seeds would be processed most effectively in vibration-pneumatic separators or, alternatively, in pneumatic separators where nut fractions obtained with the use of mesh screens can be sorted separately.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2015, 18(1); 5-14
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of the age of Scots pine (Pinus sylvestris L.) stands on the physical properties of seeds and the operating parameters of cleaning machines
Autorzy:
Kaliniewicz, Z.
Rawa, T.
Tylek, P.
Markowski, P.
Anders, A.
Fura, S.
Powiązania:
https://bibliotekanauki.pl/articles/298461.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
Scots pine
seeds
physical properties
correlations
Opis:
Critical transport velocity, the thickness, width, length, the angle of sliding friction and weight of Scots pine seeds harvested from conservation seed stands were measured. Correlations were determined between the age of parent stands (124 to 180 years old) and the above parameters of Scots pine seeds. Significant correlations were found between the age of parents stands and the weight, dimensions and the angle of sliding friction of seeds. Such a correlation was not observed for critical transport velocity. The noted correlations were presented as first-order equations which show that among the studied seed properties, average seed weight changed to the highest degree – it decreased by ca. 15% as Scots pine trees grew older.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2013, 16(1); 63-72
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physical and mechanical properties of the black turnip root flesh
Autorzy:
Starek, A.
Kusińska, E.
Guz, T.
Powiązania:
https://bibliotekanauki.pl/articles/410690.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
black turnip
physical properties
sampling site
Opis:
The paper presents the results of measurement of the basic physical properties of black turnip and the results of studies on the impact of sampling site on the textural properties of its pulp. Selected texture indices, i.e. hardness, elasticity, cohesiveness and chewiness, were determined using the TPA double compression test. The tests were carried out on samples taken from well-defined root layers (upper layer, middle layer, lower layer) and zones (A, B, C) of black turnip, because of its structural heterogeneity. The samples were compressed at the longitudinal and transverse direction of the fibers relative to the compressing device movement. The results obtained were statistically analyzed using the Statistica 10.0 program. The research has shown that the site of sampling and the direction of fiber positioning have a significant impact on the value of all the black turnip texture parameters.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2018, 7, 1; 127-136
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of Physical, Chemical and Mechanical Properties of Sri Lankan Coir Fibers
Autorzy:
Dharmaratne, Prasad Dhammika
Galabada, Harsha
Jayasinghe, Randika
Nilmini, Renuka
Halwatura, Rangika Umesh
Powiązania:
https://bibliotekanauki.pl/articles/1838275.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
coir fibre
characterization
physical properties
chemical properties
mechanical properties
Opis:
This study was carried out to determine the characterization of brown coir fiber which is used as a potential reinforcement in polymer composites. The fiber is extracted from the husk of the coconut seeds which are collected in Sri Lanka. Anyhow the above-mentioned characterization can hardly be seen when it comes to the Sri Lankan context. Since the evaluation of their physical, mechanical, and chemical properties are significant before commencing the material development process and applications for this fiber. Several testing were carried out to evaluate the above-mentioned properties. There, the functional groups of coir fiber were obtained by Fourier Transform Infrared analysis and Crystallinity Index and Crystallite size were determined by X-ray diffraction analysis. The surface morphology and cross-sectional features were investigated through Scanning Electron Microscopy. The thermo-gravimetric method was adopted to study the thermal stability of coir fiber. The density and diameter of coir fiber were measured utilizing pychometric method and optical microscope respectively. Tensile strength was measured using an electronic tensometer and then find out the tensile strength, modulus of elasticity, and elongation at breaking point. The average density of brown coir fibers was 1.018 g/cm3 and average diameters were 0.30 mm. The Crystallinity Index and the crystal-line size were 37.28% and 0.4331 nm respectively. Ultimate tensile strength, Young’s modulus, and Elongation of the coir fiber were ranging from 94–159 MPa, 1.2–1.8 GPa, and 21–67%, respectively.
Źródło:
Journal of Ecological Engineering; 2021, 22, 6; 55-65
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 291

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