Skocz do pozycji: 1.

Tytuł:

Flow coefficient of the aggregates as a parameter characterizing the suitability of non-cohesive soils for earthworks

Autorzy:

Majer, Stanisław

Powiązania:

https://bibliotekanauki.pl/articles/118735.pdf

Data publikacji:

2020

Wydawca:

Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie

Tematy:

flow coefficient of aggregates
uniformity coefficient

Opis:

The article presents the results of the flow coefficient of aggregate for 30 sands and aggregates. The introduction of European standards for the assessment of construction aggregates over 20 years ago introduced a number of new testing methods not previously used in Poland. One of them is the flow coefficient of aggregate, popularly called aggregate angularity. The method of determination is given in the standard PN-EN 933-6:2014. This standard defines the method of determining the index for coarse aggregates with grain sizes between 4 and 20 mm and fine aggregates with grain sizes below 2 mm. This test is particularly important when designing mineral-asphalt mixtures. Aggregate angularity, particularly in fine aggregates, is the main factor influencing the workability of mixtures. The flow time through the apparatus depends on the degree of roundness and form of the grain. The study determined the relationship between the flow coefficient of aggregate and CBR in relation to the uniformity coefficient. This indicator is still considered to be one of the main parameters that affect the suitability of non-cohesive soils in earthworks. It was proven that Ecs is more dependent on CBR than CU.

Źródło:

Scientific Review Engineering and Environmental Sciences; 2020, 29, 3; 298-307
1732-9353

Pojawia się w:

Scientific Review Engineering and Environmental Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 2.

Tytuł:

Effect of Liquid Forging Pressure on Solubility and Freezing Coefficients of Cast Aluminum 2124, 2218 and 6063 Alloys

Autorzy:

Tirth, Vineet
Arabi, Amir

Powiązania:

https://bibliotekanauki.pl/articles/354280.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

liquid forging
porosity
hardness
solubility coefficient
freezing coefficient

Opis:

Liquid forging alias squeeze casting gives the combined advantage of casting and forging. Optimum process parameters are important to get a cost-efficient process. In this study, four materials have been identified, which are extensively used in industries. These materials are commercially pure Al and three Al-alloys namely, 2124, 2218 and 6063. The pouring temperature and the mold temperature is maintained at 700°C and 250°C respectively. The materials were developed at seven pressure variations from 0 to 150 MPa. The effect of the pressure on the microstructures, porosity, and hardness has been reported. The coefficient of solubility is estimated for all materials and a polynomial relationship is found to be the best fit with the applied pressure. The pressure of 100 MPa gives better increment in hardness. The melting point and the freezing coefficient of the materials under study have been determined. A linear relationship between the pressure and the freezing time is deduced. It is observed that the solubility and the freezing coefficients depend on the pressure as well, in addition to the composition and temperature.

Źródło:

Archives of Metallurgy and Materials; 2020, 65, 1; 357-366
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 3.

Tytuł:

Reactive solute transport in blood flow through a permeable capillary

Autorzy:

Debnath, S.
Roy, A. K.
Bég, O. A.

Powiązania:

https://bibliotekanauki.pl/articles/38695392.pdf

Data publikacji:

2022

Wydawca:

Instytut Podstawowych Problemów Techniki PAN

Tematy:

capillary
axial flow
radial flow
solute dispersion
Gill decomposition
filtration coefficient
exchange coefficient
advection coefficient

Opis:

The present analysis discusses the solute transport process in a steady 2D (axial and radial) laminar flow of blood through a permeable, finite length capillary. Blood is treated as a homogeneous Newtonian fluid and the solute is absorbed at the capillary wall with a linear irreversible reaction rate. The velocity profile is obtained by a regular perturbation technique, whereas the transport coefficients depicted by the Gill generalized dispersion model are solved numerically. A number of different scenarios are considered, namely transport with no-reaction, weak absorption, strong absorption, low filtration or high filtration, etc. In the initial stages, the temporal behaviour of the dispersion coefficient is identical to those cases when there is no radial velocity. For the combined effect of radial and axial velocities, however, the dispersion coefficient is lower for a high absorption rate than for a weak absorption rate. Diffusion is accelerated with higher values of filtration coefficient. Owing to the opposite effects of radial diffusion and radial velocity, the solute particles require more time to reach the steady state. The analysis finds applications in, for example, reactive nutrient and pharmacological transport in capillary hemodynamics.

Źródło:

Archives of Mechanics; 2022, 74, 2-3; 173-200
0373-2029

Pojawia się w:

Archives of Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 4.

Tytuł:

Heave motion of a vertical cylinder with heave plates

Autorzy:

Ciba, Ewelina

Powiązania:

https://bibliotekanauki.pl/articles/1573695.pdf

Data publikacji:

2021

Wydawca:

Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa

Tematy:

spar platforms
heave plates
damping coefficient
added mass coefficient

Opis:

The shape of a vertical cylinder resembles the classic form of a spar platform. Spar platforms are floating platforms that are successfully used in waters of great depths and have several advantages that mean they are readily used in the oil industry. Many of these advantages are also relevant to their application for offshore wind turbines, which is currently being considered. In the hydrodynamic analysis of spar platforms, the determination of their hydrodynamic coefficients plays an important role. They can be determined based on the free decay test. The study presents a method for determining the hydrodynamic coefficients of an object based on the free decay test. The results of free oscillation calculations with the help of numerical fluid mechanics tools are presented and compared with the results of the experiment and analytical solution. The application of determined coefficients and their significance for floating platforms are discussed. The influence of change in the form of an additional damping element on the behaviour of spar structures is shown.

Źródło:

Polish Maritime Research; 2021, 1; 42-47
1233-2585

Pojawia się w:

Polish Maritime Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 5.

Tytuł:

The Influence of the Presence of Vegetations in Floodplains on Flood Risks

Autorzy:

Walczak, N.
Hammerling, M.
Spychała, M.
Nieć, J.

Powiązania:

https://bibliotekanauki.pl/articles/123654.pdf

Data publikacji:

2015

Wydawca:

Polskie Towarzystwo Inżynierii Ekologicznej

Tematy:

flood area
flow velocity
resistance coefficient
roughness coefficient
vegetation

Opis:

The movement of water on flood areas depends mainly on the geometric parameters of vegetation, which as a dynamic factor causes a high changeability of flow conditions during the year. The actual ecological trend, whereby there is a tendency to leave the plants in the floodplain, imposes the necessity on engineers to develop accurate methods of determining the effect of vegetation on what used to be once a commonly occurring flood risk. According to the report on national security risk, elaborated by the Government Security Centre, flooding is the most common such risk. This is most likely to occur among all the risks included in the National Crisis Management Plan and brings the greatest number of negative effects. In order to mitigate the negative phenomena related to floodplains, the methodology and calculation of the average flows, using the Maninng and Darcy-Weisbach models is presented.

Źródło:

Journal of Ecological Engineering; 2015, 16, 5; 160-167
2299-8993

Pojawia się w:

Journal of Ecological Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 6.

Tytuł:

The Method of Removal Yttrium (III) and Ytterbium (III) From Dilute Aqueous Solutions

Autorzy:

Lobacheva, O.
Dzhevaga, N.
Danilov, A.

Powiązania:

https://bibliotekanauki.pl/articles/123428.pdf

Data publikacji:

2016

Wydawca:

Polskie Towarzystwo Inżynierii Ekologicznej

Tematy:

ion flotation
sodium dodecyl sulfate
distribution coefficient
separation coefficient
removal

Opis:

Yttrium (III) and ytterbium (III) cations ion flotation from diluted aqueous solutions in the presence of chloride ions using sodium dodecyl sulfate as collector agent were studied. Y (III) and Yb (III) distribution and recovery coefficients as a function of aqueous phase рН value at different sodium chloride concentrations were received. Yttrium (III) and ytterbium (III) chloro and hydroxo complexes instability constants were calculated. The calculation of separation coefficient at рН specified values depending on chloride ion concentration was conducted. Maximum separation coefficient was observed when chloride concentration of 0.01 M is 50 at рН 7.8. Ksep is minimal in nitrate medium ans is 3 at рН 7.0. At sodium chloride concentration of 0.05 М Ksep is 9 at рН 7.8.

Źródło:

Journal of Ecological Engineering; 2016, 17, 2; 38-42
2299-8993

Pojawia się w:

Journal of Ecological Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 7.

Tytuł:

Impact of friction coefficient on particles circulation velocity calculated by euler-lagrange model in spouted bed apparatus for dry coating

Autorzy:

Ludwig, W.

Powiązania:

https://bibliotekanauki.pl/articles/297983.pdf

Data publikacji:

2018

Wydawca:

Uniwersytet Warmińsko-Mazurski w Olsztynie

Tematy:

spout-fluid bed
friction coefficient
restitution coefficient
Euler-Lagrange approach

Opis:

This paper is a continuation of research concerning gas-solid flow modelling using the Euler-Lagrange approach in a spout-fluid bed apparatus. The major challenge in this case was to determine the friction coefficient for particles hitting against the walls of the apparatus. On the basis of the properties of similar materials the value of this quantity was estimated at 0.2. Therefore, it proved useful to check the model’s sensitivity to the value of this parameter. The study investigated the effect of friction coefficient on calculated values of particles velocity in the draft tube and the annular zone of the device for various volumes of the circulating bed. In the course of calculations, a relatively small influence of friction coefficient on particles velocity was observed in the tested zones of the apparatus. The changes were most visible for large volumes of the bed, which was connected with an increase in the number of collisions of particles with the walls.

Źródło:

Technical Sciences / University of Warmia and Mazury in Olsztyn; 2018, 21(4); 303-321
1505-4675
2083-4527

Pojawia się w:

Technical Sciences / University of Warmia and Mazury in Olsztyn

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 8.

Tytuł:

Virtual synchronous generator frequency response study of energy computing and storage devices

Autorzy:

Zhang, Baoge
Ping, Shanyan
Long, Yi
Jiao, Yuemin
Wu, Boxiang

Powiązania:

https://bibliotekanauki.pl/articles/2172798.pdf

Data publikacji:

2022

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

damping coefficient
energy storage capacit
inertia coefficient
virtual synchronous machine

Opis:

Renewable energy sources are connected to the grid through inverters, resulting in reduced grid inertia and poor stability. Traditional grid-connected inverters do not have the function of voltage and frequency regulation and can no longer adapt to the new development. The virtual synchronous generator (VSG) has the function of voltage and frequency regulation and has more outstanding advantages than the traditional inverter. Based on the principle of the VSG, the relationship between energy storage capacity, frequency response and output power of the VSG is derived, and the relationship between the virtual inertia coefficient, damping coefficient and frequency characteristics of the VSG and output power is revealed. The mathematical model is established and modeled using the Matlab/Simulink simulation software, and the simulation results verify the relationship between energy storage capacity and frequency response and the output power of the VSG.

Źródło:

Archives of Electrical Engineering; 2022, 71, 4; 895--907
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 9.

Tytuł:

Asymmetrical PZT Applied to Active Reduction of Asymmetrically Vibrating Beam – Semi-Analytical Solution

Autorzy:

Brański, Adam
Kuras, Romuald

Powiązania:

https://bibliotekanauki.pl/articles/31339957.pdf

Data publikacji:

2022

Wydawca:

Polska Akademia Nauk. Czasopisma i Monografie PAN

Tematy:

beam
actuator (PZT)
active vibration reduction
vibration reduction coefficient
effectiveness coefficient.

Opis:

The article extended the idea of active vibration reduction of beams with symmetric modes to beams with asymmetric modes. In the case of symmetric modes, the symmetric PZT (s-PZT) was used, and the optimization of the problem led to the location of the s-PZT centre at the point with the greatest beam curvature. In the latter case, the asymmetric modes that occur due to the addition of the point mass cause an asymmetric distribution of the bending moment and transversal displacement of a beam. In this case, the optimal approach to the active vibration reduction requires both new asymmetric PZT (a-PZT) and its new particular distribution on the beam. It has been mathematically determined that the a-PZT asymmetry point (a-point), ought to be placed at the point of maximum beam bending moment. The a-PZT asymmetry was found mathematically by minimizing the amplitude of the vibrations. As a result, it was possible to formulate the criterion of the maximum bending moment of the beam. The numerical calculations confirmed theoretical considerations. So, it was shown that in the case of asymmetric vibrations, the a-PZTs reduced vibrations more efficiently than the s-PZT.

Źródło:

Archives of Acoustics; 2022, 47, 4; 555-564
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 10.

Tytuł:

New paradigms of quantification of economic efficiency in the transport sector

Autorzy:

Poliak, Milos
Svabova, Lucia
Konecny, Vladimir
Zhuravleva, Natalia Aleksandrovna
Culik, Kristian

Powiązania:

https://bibliotekanauki.pl/articles/19233644.pdf

Data publikacji:

2021

Wydawca:

Instytut Badań Gospodarczych

Tematy:

transport
coefficient
calculation
cost

Opis:

Research background: In determining the prices in road transport, carriers usually use the calculations based on a so-called routes utilisation coefficient, which allows the carrier to also take the possibility of the return rides without load into account. Currently, it is usually used as a constant from the interval from zero to one. Purpose of the article: Considering a different offer of return transport from individual European Union (EU) countries, it can be assumed that the routes utilisation coefficient should have different values because there is a varying level of non-zero probability that the vehicle will return without a load. This study therefore proposes a new approach to determining the value of this coefficient based on transport direction. The study also aims to identify clusters of EU countries, for which the common value of the coefficient should be set. Methods: The Analysis of Variance (ANOVA) test was used to verify the assumption of the differences among the means of transport offers. Cluster analysis was used to identify the aforementioned groups of countries. This analysis is based on real data on transport offers to Slovakia from 18 different EU countries. Findings & value added: The results of the analysis can also be used in other EU countries because if significant differences in transport offers to Slovakia exist in individual countries, there is a reasonable assumption that this conclusion will also be valid in other countries. The analysis demonstrated that it is more appropriate to use the routes utilisation coefficient with various values, dependent on the transport direction. For the transport companies, implementation of the obtained results into practice is beneficial to increase their competitiveness through the more precise setting of transport prices, but also to the optimisation of the transport price itself with regard to the expected costs.

Źródło:

Oeconomia Copernicana; 2021, 12, 1; 193-212
2083-1277

Pojawia się w:

Oeconomia Copernicana

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 11.

Tytuł:

On coefficient inequalities in the Carathéodory class of functions

Autorzy:

Lecko, Adam

Powiązania:

https://bibliotekanauki.pl/articles/1207925.pdf

Data publikacji:

2000

Wydawca:

Polska Akademia Nauk. Instytut Matematyczny PAN

Tematy:

Carathéodory class
coefficient inequalities

Opis:

Some inequalities are proved for coefficients of functions in the class P(α), where α ∈ [0,1), of functions with real part greater than α. In particular, new inequalities for coefficients in the Carathéodory class P(0) are given.

Źródło:

Annales Polonici Mathematici; 2000, 75, 1; 59-67
0066-2216

Pojawia się w:

Annales Polonici Mathematici

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 12.

Tytuł:

Determination of roughness coefficient of the underside of ice cover

Autorzy:

Majewski, W.

Powiązania:

https://bibliotekanauki.pl/articles/241490.pdf

Data publikacji:

2003

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

ice cover
roughness coefficient

Opis:

The formation of ice cover in winter on rivers, channels and run-of-reservoirs, changes flow characteristics significantly. Calculations of water surface profiles or discharge along a river reach with ice cover by means of 1-D models, requires detailed values of the roughness coefficients of the river bed and underside of the ice cover. Numerous studies dealing with roughness coefficients of the river bed with free surface flow were carried out in the past, however, very few investigations were performed on the determination of the roughness coefficient of the underside of ice cover. Data of calculations indicate that this coefficient may vary considerably with space and time, depending on the character of the ice cover, flow characteristics and meteorological conditions. In 1-D models roughness coefficient of the bed and of the underside of the ice cover must be combined into one composite roughness coefficient. The paper presents determination of roughness coefficient of the underside of ice cover based on velocity distributions in the Vistula River cross-sections with ice cover. It may be assumed that vertical velocity distribution has a logarithmic character in the regions near the bottom and ice cover. Taking into account this assumption the procedure for the calculation of Darcy-Weisbach friction factor f and Manning roughness coefficient n is proposed, basing on the data of velocity measurements in a given vertical. It was found that roughness coefficient of the underside of the ice cover varies in a much larger range than the bottom roughness coefficient and depends very much on the character of the ice cover.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2003, 50, 3; 219-228
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 13.

Tytuł:

Sharing the Growth Dividend: Analysis of Inequality in Asia

Autorzy:

Jain-Chandra, Sonali
Kinda, Tidiane
Kochhar, Kalpana
Piao, Shi
Schauer, Johanna

Powiązania:

https://bibliotekanauki.pl/articles/2042921.pdf

Data publikacji:

2019-09-04

Wydawca:

Uniwersytet Warszawski. Wydawnictwo Naukowe Wydziału Zarządzania

Tematy:

Inequality
Gini coefficient
Asia

Opis:

This paper focusses on income inequality in Asia, its drivers and policies to combat it. It finds that income inequality has risen in most of Asia, in contrast to many other regions. While in the past, rapid growth in Asia has come with equitable distribution of the gains, more recently fastgrowing Asian economies have been unable to replicate the “growth with equity” miracle. There is a growing consensus that high levels of inequality can hamper the pace and sustainability of growth. The paper argues that policies could have a substantial effect on reversing the trend of rising inequality. It is imperative to address inequality of opportunities, in particular to broaden access to education, health, and financial services. Also, fiscal policy could combat rising inequality, including by expanding and broadening the coverage of social spending, improving tax progressivity, and boosting compliance. Further efforts to promote financial inclusion, while maintaining financial stability, can help.

Źródło:

Journal of Banking and Financial Economics; 2019, 2(12); 5-28
2353-6845

Pojawia się w:

Journal of Banking and Financial Economics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 14.

Tytuł:

Phenomenon of force impulse restitution in collision modelling
Zjawisko restytucji impulsów sił chwilowych w modelowaniu zderzeń

Autorzy:

Michalczyk, J.

Powiązania:

https://bibliotekanauki.pl/articles/280769.pdf

Data publikacji:

2008

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

collision
coefficient of restitution

Opis:

The rightness of the Newtonian hypothesis concerning a constat value of the coefficient of restitution R has been confirmed in the paper with reference to collisions in which the loss of energy occurs in conseqence of material damping. For collisions of different nature, when R depends on the density of the energy flux _, the paper points to the possibility of extending this notion to the case of eccentric collision. The possibility of describing R as a random function of _ has been shown as well.
W pracy wykazano, że Newtonowska idea wspłółczynnika restytucji R = const jest słuszna w odniesieniu do zderzeń, w których strata energii powstaje głównie na skutek tłumienia materiałowego. Dla zderzeń o innym charakterze, dla których R zależy od gęstości strumienia energii _, wskazano na możliwość rozszerzenia tego pojęcia na przypadek zderzenia mimośrodowego. W pracy wskazano również na celowość opisania R jako funkcji losowej parametru _ i podano formułę na siłę kontaktową zapewniającą uzyskanie założonej wartości R podczas symulacji cyfrowej procesu zderzenia.

Źródło:

Journal of Theoretical and Applied Mechanics; 2008, 46, 4; 897-908
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 15.

Tytuł:

Uniformly convex functions II

Autorzy:

Ma, Wancang
Minda, David

Powiązania:

https://bibliotekanauki.pl/articles/1311788.pdf

Data publikacji:

1993

Wydawca:

Polska Akademia Nauk. Instytut Matematyczny PAN

Tematy:

convex functions
coefficient bounds

Opis:

Recently, A. W. Goodman introduced the class UCV of normalized uniformly convex functions. We present some sharp coefficient bounds for functions f(z) = z + a₂z² + a₃z³ + ... ∈ UCV and their inverses $f^{-1}(w) = w + d₂w² + d₃w³ + ...$. The series expansion for $f^{-1}(w)$ converges when $|w| < ϱ_f$, where $0 < ϱ_f$ depends on f. The sharp bounds on $|a_n|$ and all extremal functions were known for n = 2 and 3; the extremal functions consist of a certain function k ∈ UCV and its rotations. We obtain the sharp bounds on $|a_n|$ and all extremal functions for n = 4, 5, and 6. The same function k and its rotations remain the only extremals. It is known that k and its rotations cannot provide the sharp bound on $|a_n|$ for n sufficiently large. We also find the sharp estimate on the functional |μa²₂ - a₃| for -∞ < μ < ∞. We give sharp bounds on $|d_n|$ for n = 2, 3 and 4. For $n = 2, k^{-1}$ and its rotations are the only extremals. There are different extremal functions for both n = 3 and n = 4. Finally, we show that k and its rotations provide the sharp upper bound on |f''(z)| over the class UCV.

Źródło:

Annales Polonici Mathematici; 1993, 58, 3; 275-285
0066-2216

Pojawia się w:

Annales Polonici Mathematici

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 16.

Tytuł:

On the coefficient bodies of meromorphic univalent functions omitting a disc

Autorzy:

Tammi, Olli

Powiązania:

https://bibliotekanauki.pl/articles/1207924.pdf

Data publikacji:

2000

Wydawca:

Polska Akademia Nauk. Instytut Matematyczny PAN

Tematy:

coefficient bodies
univalent functions

Opis:

Let S(b) be the class of bounded normalized univalent functions and Σ(b) the class of normalized univalent meromorphic functions omitting a disc with radius b. The close connection between these classes allows shifting the coefficient body information from the former to the latter. The first non-trivial body can be determined in Σ(b) as well as the next one in the real subclass $Σ_{R}(b)$.

Źródło:

Annales Polonici Mathematici; 2000, 75, 1; 47-58
0066-2216

Pojawia się w:

Annales Polonici Mathematici

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 17.

Tytuł:

Laboratory tests of the aerodynamic drag coefficient of the flag as a body with low stiffness

Autorzy:

Wilk, A.
Skuta, M.

Powiązania:

https://bibliotekanauki.pl/articles/1943232.pdf

Data publikacji:

2009

Wydawca:

Politechnika Gdańska

Tematy:

aerodynamic drag coefficient
flag

Opis:

The shape and drag of bodies with small stiffness may change during the airflow. This problem refers to such bodies as flags, bands, banners, flapping sails as well as blades and cables which vibrate due to the flow. Laboratory tests carried out to point out the aerodynamic drag coefficient of a flag are discussed in this article. The laboratory tests were carried out in an aerodynamic tunnel at different airflow velocities for flags with different dimensions made of fabrics of different roughness and stiffness. The drag coefficient value decreases with the increasing airflow velocity. The drag coefficient is higher for materials with higher roughness. The drag coefficient value is also influenced by the fabric stiffness and kind of edge. Great engineering importance to the stability of a structure (e.g. a flag mast) and the safety of nearby persons and buildings are attached to the analyzed problem.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2009, 13, 1-2; 5-14
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 18.

Tytuł:

Thermal conductivity of food products
Przewodność cieplna produktów spożywczych

Autorzy:

Aerlichman, V.N.
Fatychov, J.A.
Kukelka, L.
Kopec, A.

Powiązania:

https://bibliotekanauki.pl/articles/35494.pdf

Data publikacji:

2014

Wydawca:

Polska Akademia Nauk. Instytut Agrofizyki PAN

Tematy:

food product
thermal conductivity
thermal diffusivity
thermal diffusivity coefficient
heat conductivity coefficient

Opis:

The presented work is focused on the food thermal characteristics calculation methods (heat conductivity coefficient and thermal diffusivity coefficient a). Thermal characteristics of food are important in food industry and define the intensiveness of technological processes of food refrigeration and thermal treatment, energy consumption for their realization and technological equipment production rate. They are also needed for the building and validation of mathematical models of heat transfer in food products which are useful in the design and optimisation of freezing, heating, cooking and cooling pro-cesses and equipment. It is not easy to define the food thermal characteristics. Difficulties arise from their heterogeneity, high labour consumption and complexity of experimental sets. Methods for experimental determination of heat conductivity coefficient and thermal diffusivity coefficient a based on the regular method mode require the α → ∞ condition, which is the case of high speed of the environment which flows around the test sample, as in the case of boiling or condensing. Using the method presented in this article it is possible to determine the heat conductivity and thermal diffusivity coefficient a even in the absence of the condition α → ∞.
W pracy opisano metodę pozwalającą na obliczeniowe wyznaczenie charakterystyk cieplnych produktów spożywczych – współczynnika przewodzenia ciepłaoraz współczynnika wyrównania temperatury (dyfuzyjności cieplnej) a. Współczynniki te wpływają na przebieg procesów obróbki termicznej produktów, a także na zużycie energii i produktywność urządzeń technologicznych. Znajomość tych współczynników jest konieczna do tworzenia modeli matematycznych wymiany ciepła w produktach spożywczych, użytecznych w projektowaniu i optymalizacji procesów i urządzeń do mrożenia, ogrzewania, gotowania czy schładzania produktów. Określenie właściwości cieplnych żywności nie jest łatwe. Trudności wynikają z różnorodności produktów spożywczych, pracochłonności i złożoności stanowisk badawczych. Sposoby eksperymentalnego wyznaczania ww. współczynników oparte na metodzie stanu uporządkowane-go wymagają spełnienia warunku α→∞, co ma miejsce w przypadku dużych prędkości środowiska omywającego badaną próbkę, przy gotowaniu lub kondensacji. Za pomocą przedstawionej w pracy metody możliwe jest wyznaczenie współczynnika przewodzenia ciepła i współczynnika dyfuzyjności cieplnej a nawet w przypadku braku spełnienia warunku α→∞.

Źródło:

Acta Agrophysica; 2014, 21, 2
1234-4125

Pojawia się w:

Acta Agrophysica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 19.

Tytuł:

A note on correlation coefficient between random events

Autorzy:

Stępniak, Czesław

Powiązania:

https://bibliotekanauki.pl/articles/729754.pdf

Data publikacji:

2015

Wydawca:

Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii

Tematy:

correlation coefficient between random events
correlation coefficient for random variables
synergy phenomenon

Opis:

Correlation coefficient is a well known measure of (linear) dependence between random variables. In his textbook published in 1980 L.T. Kubik introduced an analogue of such measure for random events A and B and studied its basic properties. We reveal that this measure reduces to the usual correlation coefficient between the indicator functions of A and B. In consequence the resuts by Kubik are obtained and strenghted directly. This is essential because the textbook is recommended by many universities in Poland.

Źródło:

Discussiones Mathematicae Probability and Statistics; 2015, 35, 1-2; 57-60
1509-9423

Pojawia się w:

Discussiones Mathematicae Probability and Statistics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 20.

Tytuł:

Ocena wybranych cech fizycznych bulw ziemniaków
Evaluation of selected physical properties of potato bulbs

Autorzy:

Kiełbasa, P.

Powiązania:

https://bibliotekanauki.pl/articles/292210.pdf

Data publikacji:

2005

Wydawca:

Polskie Towarzystwo Inżynierii Rolniczej

Tematy:

współczynnik tarcia
współczynnik sferyczności
bulwa
ziemniak
friction coefficient
sphericity coefficient
bulb
potato

Opis:

Właściwości fizyczne bulw determinują proces zbioru i obróbki pozbiorowej plonu ziemniaków, dlatego ich wyrównanie zarówno w obrębie odmiany jak i pomiędzy odmianami jest pożądane, ponieważ wpływa na sprawność separacji zbieranego plonu. Celem badań było wyznaczenie współczynnika tarcia zewnętrznego i współczynników sferyczności bulw. Badane odmiany uprawiano na piasku gliniastym lekkim. Zaobserwowano wpływ odmiany na badane parametry bulw.
Physical properties of potato bulbs determine the process of harvesting and of postharvest treatment of potato crops, therefore the balance between and among species is desired, as it affects the efficiency of separating the crop being harvested. The study was aimed at determining the external friction coefficient and bulb sphericity coefficients. Examined species were grown on light loamy sand. The influence of specie on examined parameters of bulbs has been revealed.

Źródło:

Inżynieria Rolnicza; 2005, R. 9, nr 6, 6; 305-313
1429-7264

Pojawia się w:

Inżynieria Rolnicza

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 21.

Tytuł:

PZT Asymmetrical Shape Optimization in Active Vibration Reduction of Triangular Plates

Autorzy:

Brański, Adam
Kuras, Romuald

Powiązania:

https://bibliotekanauki.pl/articles/31339818.pdf

Data publikacji:

2023

Wydawca:

Polska Akademia Nauk. Czasopisma i Monografie PAN

Tematy:

triangular plate
actuator (PZT)
active vibration reduction
vibration reduction coefficient
effectiveness coefficient

Opis:

The article presents the new 2D asymmetrical PZT (a-PZT) and its effectiveness in the active reduction of triangular plate vibrations. The isosceles right triangular plate with simply supported edges was chosen as the research object. To determine the a-PZT asymmetry and its distribution on the plate, a maximum bending moment criterion for the beam was used. First of all, this criterion points out exact center location of the a-PZT. It was at the point, at which the plate bending moment has reached its maximum value. Next, at this point, it was assumed that the piezoelectric consists of active fibers located radially from the center. Each fiber acted on the plate as a separate actuator. Next, at each direction, the actuator asymmetry was found mathematically by minimizing the amplitude of the vibrations. By connecting the outer edges of individual fibers, the 2D a-PZT was obtained. It was quantitatively confirmed that the effectiveness of the new a-PZT was the best compared with the effectiveness of the standard square and the circular PZTs, adding the same exciting energy to the PZTs.

Źródło:

Archives of Acoustics; 2023, 48, 3; 425-432
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 22.

Tytuł:

Assessment of Phytoremediation of 137Cs Contaminated Soils During the Cultivation of Nectar-Pollinating Plants

Autorzy:

Razanov, Serhii
Kutsenko, Mykola
Klymenko, Mykola
Bakhmat, Mykola
Klymenko, Oleksandr
Bakhmat, Oleh
Holubieva, Tetiana
Kovalchuk, Nataliia
Mazurak, Oksana

Powiązania:

https://bibliotekanauki.pl/articles/24201711.pdf

Data publikacji:

2023

Wydawca:

Polskie Towarzystwo Inżynierii Ekologicznej

Tematy:

soil
milk thistle
white melilot
plant
phytoremediation
137Cs
accumulation coefficient
danger coefficient

Opis:

The man-made activity of mankind has led to the emergence of many global problems and caused the deterioration of the quality of the natural environment (air, water, soil). Of particular concern is the contamination of agricultural land with toxicants, in particular, radionuclides, which, entering the soil – plant – human body food chain, can reach toxic levels. Therefore, an important task is the removal of hazardous substances from the soil. Phytoremediation can be one of the effective methods for reducing its pollution. The article examines the effectiveness of phytoremediation of soils contaminated as a result of the accident at the Chernobyl nuclear power plant in certain territories of Polissia of Ukraine (Korosten district of Zhytomyr region). Nectar-pollinating plants were selected for the research, which was carried out for two years: great globe-thistle (Echinops sphaerocephalus), milk thistle (Silybum marianum), and white melilot (Melilotus albus). The results of the research showed that in the dry vegetative mass of milk thistle, great globe-thistle, and white melilot, the specific activity of 137Cs over the two years of research was in the range from 30.8 Bq/kg to 238.5 Bq/kg, the accumulation coefficient – from 0.135 to 0.985, and the hazard coefficient – from 0.055 to 0.395. The highest indicators of specific activity and accumulation coefficient of 137Cs were observed in the vegetative mass of the white melilot, which amounted to 238.5 Bq/kg and 0.96, respectively, comparatively lower values – 2.3 times and 2.3 times were found in the vegetative mass of milk thistle, 2.8 times and 7.1 times – in the vegetative mass of the great globe-thistle. At this level of accumulation of 137Cs in the vegetative mass of nectarine plants from the soil, on average, over two years of research, 1130550 Bq of this radionuclide was removed from the soil per hectare of agricultural land with milk thistle, 621250 Bq with great globe-thistle, and 2851650 Bq with white melilot. The removal of 137Cs with the vegetative mass of nectarine plants reduced the content of this radionuclide in the soil per 1 kg – from 3.4% to 8% on average over two years of research.

Źródło:

Journal of Ecological Engineering; 2023, 24, 5; 316--321
2299-8993

Pojawia się w:

Journal of Ecological Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 23.

Tytuł:

Compound Channel’s Cross-section Shape Effects on the Kinetic Energy and Momentum Correction Coefficients

Autorzy:

Ghanbari-Adivi, Elham

Powiązania:

https://bibliotekanauki.pl/articles/1837762.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

CES model
compound channel
FCF
floodplain
kinetic energy correction coefficient
momentum correction coefficient

Opis:

Since accurate estimation of the flow kinetic energy (α) and momentum (β) is not easily possible in compound channels, determining their accurate correction coefficients is an important task. This paper has used the “flood channel facility (FCF)” data and the “conveyance estimate system (CES)” model (which is 1D, but considers a term related to the secondary flow) to study how the floodplain width and the main channel wall slope and asymmetry affect the values of α and β. Results have shown that their maximum values at the highest floodplain width are, respectively, 1.36 and 1.13 times of those at the lowest case; an increase in the slope increased their maximum values by 1.05 and 1.01 times, respectively. The mean of error values showed that the CES model estimated the values α and β more accurately than the flow discharge. The maximum differences between the estimated and experimental values were 12.14% for α and 4.3% for β; for the flow discharge, it was 24.4%.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2020, 67, 1-4; 55-71
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 24.

Tytuł:

Note on the moments of random variables product

Autorzy:

Kornacki, A.

Powiązania:

https://bibliotekanauki.pl/articles/411048.pdf

Data publikacji:

2017

Wydawca:

Polska Akademia Nauk. Oddział w Lublinie PAN

Tematy:

central moment of random variable
coefficient of skewness
kurtosis
variation coefficient
approximate formula

Opis:

In this paper the formulae for central moments of independent random variables product are introduced. Generally, the formulae are very complex and not very readable, therefore the article focuses on the most important – terms of applications – moments of r = 2, 3, 4 orders. These moments occur in the determination of such characteristics as variance, skewness or kurtosis. In cases r = 3 and 4 only two random variables are considered. Apart from exact formulae in the considered situations the approximate formulae were also presented. For the variance the approximation effectiveness was also assessed.

Źródło:

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2017, 6, 4; 93-96
2084-5715

Pojawia się w:

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 25.

Tytuł:

Application of GPS receiver to road tests of automobile

Autorzy:

Sar, H.
Pokorski, J.
Fundowicz, P.
Reński, A.

Powiązania:

https://bibliotekanauki.pl/articles/242475.pdf

Data publikacji:

2013

Wydawca:

Instytut Techniczny Wojsk Lotniczych

Tematy:

automobile dynamics
air drag coefficient
rolling drag coefficient
ECE 13 Regulation
road transport

Opis:

The article presents the assessment of the possibilities of applying GPS receiver for the measurement and acquisition of the longitudinal velocity of automobile in the investigations of longitudinal dynamics of automobile. For many years for the measurement of the longitudinal velocity Correvit-L sensors are applied. Major simplification of the measurement of the velocity with the GPS receiver, compared with correlational-optical sensors Correvit-L is giving the possibility to faster prepare the automobile for examinations. The more so as only recently GPS receivers with 10 Hz sampling rate are available. In the paper is shortly described the software specially designed for the measurements that makes it possible to simultaneously measure both the longitudinal velocity signal from GPS receiver and from Correvit-L sensor in real time. Furthermore, the application of the measurement of the velocity is presented on the basis of such road tests as the attempt of accelerating through the following gears, the attempt of free deceleration and the attempt of braking according to ECE 13 Regulation. On the basis of the mentioned manoeuvers the characteristics of the vehicle’s acceleration and dynamic coefficient, rolling and air drag coefficient and the braking deceleration were determined. The paper shows also some problems connected with applying GPS receiver to measure longitudinal velocity of the automobile.

Źródło:

Journal of KONES; 2013, 20, 3; 359-366
1231-4005
2354-0133

Pojawia się w:

Journal of KONES

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 26.

Tytuł:

Optical properties of maize seeds

Autorzy:

Hernandez, A.
Cruz, O.
Ivanov, R.
Dominguez, P.
Carballo, C.
Moreno, I.

Powiązania:

https://bibliotekanauki.pl/articles/25661.pdf

Data publikacji:

2011

Wydawca:

Polska Akademia Nauk. Instytut Agrofizyki PAN

Tematy:

maize
optical absorption coefficient
photoacoustic spectroscopy
absorption coefficient
seed
optical property
raw material

Źródło:

International Agrophysics; 2011, 25, 3
0236-8722

Pojawia się w:

International Agrophysics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 27.

Tytuł:

Influence of Rolling Friction Coefficient on Inter-Particle Percolation in a Packed Bed by Discrete Element Method

Autorzy:

Zhou, H.
Luo, Z.
Zhang, T.
You, Y.
Li, H.
Zou, Z.

Powiązania:

https://bibliotekanauki.pl/articles/356261.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

inter-particle percolation
rolling friction coefficient
discrete element method;
percolation velocity
dispersion coefficient

Opis:

Rolling friction representing the energy dissipation mechanism with the elastic deformation at the contact point could act directly on particle percolation. The present investigation intends to elucidate the influence of rolling friction coefficient on inter-particle percolation in a packed bed by discrete element method (DEM). The results show that the vertical velocity of percolating particles decreases with increasing the rolling friction coefficient. With the increase of rolling friction coefficient, the transverse dispersion coefficient decreases, but the longitudinal dispersion coefficient increases. Packing height has a limited effect on the transverse and longitudinal dispersion coefficient. In addition, with the increase of size ratio of bed particles to percolation ones, the percolation velocity increases. The transverse dispersion coefficient increases with the size ratio before D/d<14. And it would keep constant when the size ratio is greater than 14. The longitudinal dispersion coefficient decreases when the size ratio increases up to D/d=14, then increases with the increase of the size ratio. External forces affect the percolation behaviours. Increasing the magnitude of the upward force (e.g. from a gas stream) reduces the percolation velocity, and decreases the dispersion coefficient.

Źródło:

Archives of Metallurgy and Materials; 2016, 61, 4; 1795-1804
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 28.

Tytuł:

Evaluation of groundwater recharge in Poland using the infiltration coefficient method

Autorzy:

Tarka, R.
Olichwer, T.
Staśko, S.

Powiązania:

https://bibliotekanauki.pl/articles/2060389.pdf

Data publikacji:

2017

Wydawca:

Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy

Tematy:

groundwater recharge
infiltration coefficient
Polska

Opis:

Variable methods and results are reported on groundwater recharge in Poland. The evaluation of recharge on a small scale requires the use of a single method. In order to evaluate these outcomes and their distribution, the authors have decided to verify different approaches and select the infiltration coefficient by comparison. The article is an extension of the studies on groundwater recharge conducted by the authors. The main goal is to verify previously designed values of the infiltration coefficient based on groundwater runoff from additional river basins in Poland. Total groundwater recharge from precipitation in Poland was calculated at 34,118 km3 per year, which equals 109.3 mm of water column. The obtained value is close to the average multi-year value of the groundwater runoff. Recharge constituted 18.6% of average precipitation in Poland, which was calculated at 588.5 mm. The estimated groundwater recharge value was verified referring to groundwater runoff from 37 river basins with known discharge rates in the years 1976–2005. Differences in mean groundwater runoff for the entire area (37 river basins) obtained by the infiltration coefficient method and by the use of Wundt’s method amounts to only 0.7%. Despite the simplified calculation methods, the results obtained on a small scale are more accurate than other calculations, which are based on data pertaining to precipitation, soil type, land use, topography of the area, and depth to the groundwater.

Źródło:

Geological Quarterly; 2017, 61, 2; 384--395
1641-7291

Pojawia się w:

Geological Quarterly

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 29.

Tytuł:

Wear tests of sliding surfaces in the environment of mixtures of lubricating oils and refrigerants

Autorzy:

Górny, K.
Tyczewski, P.
Zwierzycki, W.

Powiązania:

https://bibliotekanauki.pl/articles/101978.pdf

Data publikacji:

2014

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

refrigerant
refrigerating oil
friction coefficient

Opis:

Elements of refrigeration compressors may be exposed to various types of wear pro¬cesses, depending on the used oils and refrigerants. The presence of the refrigerant makes the lubricating properties and anti-oil mixture - factor much worse than in case of the lack of refrigerant oil. Current regulations on the use of ODS phase-out of working require refrigeration synthetic refrigerants HCFC (e.g. popular R22). The paper presents the effect of different mixtures of oils and refrigerants on friction coefficient and surface condition of cast iron and aluminium PA6. Tests were performed on a prototype machine using frictional node type block-on-ring, which is located inside a pressure chamber that simulates the refrigeration compressor. The results of the study confirm the possibility of using green refrigerant R290 (propane) as a substitute for R22, while keeping the existing mineral oil.

Źródło:

Advances in Science and Technology. Research Journal; 2014, 8, 21; 49-53
2299-8624

Pojawia się w:

Advances in Science and Technology. Research Journal

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 30.

Tytuł:

Supersmarność oraz nowe materiały supersmarne wytwarzane napylaniem proszkowym
Superlubricity and new superlubricant materials made by powder spraying

Autorzy:

Leshchynsky, V.
Wiśniewska-Weinert, H.

Powiązania:

https://bibliotekanauki.pl/articles/211744.pdf

Data publikacji:

2006

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Obróbki Plastycznej

Tematy:

solid lubricant
nanoparticles
friction coefficient

Opis:

O supersmarności zazwyczaj mówimy wówczas, kiedy dwie stykające się powierzchnie wykazują brak oporu podczas tarcia ślizgowego. Artykuł opisuje zjawisko ultra-niskiego tarcia dzięki zastosowaniu powłok z nanocząstek MoS2, wynikiem którego jest otrzymanie ultra-niskiego współczynnika tarcia. Autorzy wskazują, że zastosowanie wielokomponentowych supersmarnych powłok otrzymanych metodą napylania proszkowych materiałów zawierających dodatki smaru stałego MoS2 znacznie zmniejsza współczynnik tarcia w warunkach suchego tarcia ślizgowego.Przedstawiono charakterystykę tribologiczną powłok zawierających MoS2, przeprowadzono testy tarciowo-zużyciowe w podwyższonej temperaturze. Określono wartość współczynnika tarcia w czasie.
Superlubricity is the state in which two contacting surfaces exhibit no resistance to sliding. The work describes a ultra-low friction phenomenon due to application of MoS2 nanoparticle coatings results in ultra-low friction coefficients in ambient atmosphere.It is shown the concept of superlubricity of combined coatings can be effectively used to improve the friction under dry sliding conditions. The additional application of solid lubricant films by powder spraying and MoS2 precipitation technologies results in low friction coefficients and a good tribological behaviour under dry sliding conditions. To clarify the tribological characteristics of MoS2 films, friction experiments were conducted at stick-slip regime at the high temperature. It was found that the friction coefficient value was very low and stable for prolonged periods.

Źródło:

Obróbka Plastyczna Metali; 2006, 17, 4; 43-48
0867-2628

Pojawia się w:

Obróbka Plastyczna Metali

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 31.

Tytuł:

Influence of the irregularity coefficient of loading on calculated fatigue life

Autorzy:

Pawliczek, R.
Kluger, K.

Powiązania:

https://bibliotekanauki.pl/articles/281651.pdf

Data publikacji:

2013

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

fatigue
irregularity coefficient
mean stress

Opis:

The paper presents comparison of two methods for determination of the fatigue damage degree in a material subjected to random loadings with participation of the mean loading and including the irregularity coefficient of the loading. The authors estimated effectiveness of the method where the stress history was transformed considering the global mean value of the load history and the method for which the stress mean value of the distinguished loading cycles was taken into account. When the irregularity coefficient of loading increases, we can observe significant divergences of the calculated fatigue life of the material related to the model of amplitude transformation because of the loading mean value.

Źródło:

Journal of Theoretical and Applied Mechanics; 2013, 51, 4; 791-798
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 32.

Tytuł:

Determination of heat transfer coefficient in the phase-change heat storage device

Autorzy:

Pavlenko, A. M.
Koshlak, H. V.
Piotrowski, J. Z.

Powiązania:

https://bibliotekanauki.pl/articles/402411.pdf

Data publikacji:

2016

Wydawca:

Politechnika Świętokrzyska w Kielcach. Wydawnictwo PŚw

Tematy:

heat transfer coefficient
heat accumulator

Opis:

This article describes information about the research of the heat transfer coefficient from air to water on the basis of comparison of theoretical calculations with the use of mathematical modeling and experimental studies of small copies of the heat accumulator to operate in the charging mode and discharging process without phase change.

Źródło:

Structure and Environment; 2016, 8, 4; 278-281
2081-1500

Pojawia się w:

Structure and Environment

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 33.

Tytuł:

Analysis of the impact of surface layer parameters on wear intensity of friction pairs
Analiza wpływu parametrów warstwy wierzchniej na intensywność zużycia par ciernych

Autorzy:

Burdzik, R.
Folęga, P.
Łazarz, B.
Stanik, Z.
Warczek, J.

Powiązania:

https://bibliotekanauki.pl/articles/355798.pdf

Data publikacji:

2012

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

surface layer
wear
friction coefficient

Opis:

The study discussed in the paper consisted in testing the impact of surface layer parameters on wear intensity of friction pair components. The study was conducted having taken additional operational factors into consideration, namely the friction conditions (presence of lubricant) and the value of loads affecting the contact zone of the samples being tested. The study constituted laboratory tests of wear and were conducted by means of a T-01M type laboratory test stand used to experimentally analyse frictional cooperation of various materials used in structural components of motor vehicles. The friction pairs examined were previously operating in a pin-on-disk system under various conditions. The materials of the friction pairs tested at the stand were subjected to heat treatment and chemical processing in order to attain specific parameters of their surface layers. The studies conducted enabled determination of the abrasive wear values for the material samples tested having entailed the surface layer parameters and the factors related to operation of actual structural components used in automotive engineering. An additional advantage of the studies conducted was the possibility to establish actual coefficients of friction occurring in specific friction pairs. Establishing the actual values of friction coefficients for the materials of friction pairs under specific conditions and having taken the impact of the surface layer parameters into consideration enabled identification of the reasons for excessive surface wear. Hence a reference can be made between the stationary tests undertaken and actual components cooperating with one another in kinematic pairs of machines. The utilitarian premise resulting from the studies conducted is the necessity of paying particular attention to surface layer parameters while designing friction pairs for machines.
W pracy badano wpływ parametrów warstwy wierzchniej na intensywnosc zuzycia elementów pary ciernej. Badania przeprowadzono przy uwzględnieniu dodatkowych czynników eksploatacyjnych takich jak warunki tarcia (obecność środka smarnego) oraz wartosc obciążen w strefie kontaktowej badanych próbek. W ramach pracy przeprowadzono badania laboratoryjne zużycia przy wykorzystaniu stanowiska badawczego typu T-01M, na którym eksperymentalnie analizowano współpracę cierna różnych materiałów stosowanych na elementy konstrukcyjne pojazdów samochodowych. Badano pary cierne, które pracowały w układzie trzpień – tarcza w różnych warunkach. Materiały badanych na stanowisku par ciernych poddawano zabiegom cieplno-chemicznym w celu uzyskania określonych parametrów warstwy wierzchniej. Przeprowadzone badania umozliwiły wyznaczenie wielkości zuzycia sciernego badanych próbek materiałów przy uwzglednieniu parametrów warstwy wierzchniej oraz czynników związanych z eksploatacja rzeczywistych elementów konstrukcyjnych wykorzystywanych w technice motoryzacyjnej. Dodatkowym atutem przeprowadzonych badań było wyznaczenie rzeczywistych współczynników tarcia występującego w przypadku określonych par ciernych. Wyznaczanie rzeczywistych wartości współczynników tarcia materiałów par ciernych przy określonych warunkach oraz przy uwzględnieniu wpływu parametrów warstwy wierzchniej pozwala na identyfikacje przyczyn nadmiernego zużycia powierzchni. Przeprowadzone badania stanowiskowe można odnieść do rzeczywistych elementów współpracujących ze sobą w węzłach kinematycznych maszyn. Utylitarna przesłanka wynikająca z przeprowadzonych badań jest koniecznosc zwrócenia szczególnej uwagi, przy projektowaniu w częściach maszyn wezłów tarcia, na parametry warstwy wierzchniej.

Źródło:

Archives of Metallurgy and Materials; 2012, 57, 4; 987-993
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 34.

Tytuł:

Numerical modeling of the performance of a centrifugal compressor impeller with low inlet flow coefficient

Autorzy:

Kabalyk, K.
Kryłłowicz, W.

Powiązania:

https://bibliotekanauki.pl/articles/175477.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

centrifugal compressor
low flow coefficient

Opis:

The paper presents the results of computational fluid dynamics modeling of the performance of two centrifugal impellers with low inlet flow coefficients. The first impeller with the flow coefficient of 0.024 had nine main and nine splitter blades and the outlet diameter of 447 mm. The second one differed from the first one only by the lack of the splitters, 18 main blades were used instead. The numerical simulations were verified by the experimental measurements performed on a corresponding test rig. The measurements show better performance characteristics of the impeller with splitters. The main aim of the numerical research, therefore, was to identify the reasons for the existing differences in the performance of the impellers.

Źródło:

Transactions of the Institute of Fluid-Flow Machinery; 2016, 131; 97-109
0079-3205

Pojawia się w:

Transactions of the Institute of Fluid-Flow Machinery

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 35.

Tytuł:

Identification of parameters of PID controller of agricultural machines drives operation
Identyfikacja parametrów regulatora PID sterującego pracą napędów w maszynie rolniczej

Autorzy:

Maleszka, M.
Wojciechowski, J.
Osmólski, W.

Powiązania:

https://bibliotekanauki.pl/articles/334054.pdf

Data publikacji:

2016

Wydawca:

Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Maszyn Rolniczych

Tematy:

PID
controller
coefficient
regulator
współczynnik

Opis:

The article describes the determination and verification of regulator PID coefficients exampled by regulator which is a part of the control system of pumps for liquids. To implement the identification process we used functions available in Matlab. Obtained in the simulation result amounted to 93.59% of setpoint. The effectiveness of the method is illustrated by the graph allowing comparison of the preset value of the variable capacity of the pump operation with the results obtained from the simulation of the arrangement: the control system - the pump.
W artykule przedstawiono opis wyznaczenia i weryfikacji współczynników regulatora PID na przykładzie regulatora w układzie sterującym pompy do substancji płynnych. Do realizacji procesu identyfikacji zastosowano funkcje dostępne w środowisku Matlab. Otrzymany w procesie symulacji wynik wyniósł 93,59% nastawy. Skuteczność metody zilustrowano za pomocą wykresu umożliwiającego porównanie zadanych zmiennych wartości wydajności pracy pompy z wynikami uzyskanymi z symulacji pracy układu: system sterujący - pompa.

Źródło:

Journal of Research and Applications in Agricultural Engineering; 2016, 61, 1; 48-51
1642-686X
2719-423X

Pojawia się w:

Journal of Research and Applications in Agricultural Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 36.

Tytuł:

Small high density lipoprotein subclasses: some of their physico-chemical properties and stability in solution.

Autorzy:

Atmeh, Ragheb
Abd Elrazeq, Issa

Powiązania:

https://bibliotekanauki.pl/articles/1041440.pdf

Data publikacji:

2005

Wydawca:

Polskie Towarzystwo Biochemiczne

Tematy:

small high density lipoproteins
diffusion coefficient
surface charge
molecular shape
coefficient of friction
stability

Opis:

Small high density lipoproteins (SHDL) contribute to the protection from atherosclerosis, but detailed information about their properties is not available yet. We isolated four of the smallest HDL subclasses that contain apoA-I alone, the small lipoprotein A-I (SLpAI), by their separation on gradient polyacrylamide gel followed by electroelution. Their physico-chemical properties were calculated from their displacement in non-denaturing gradient polyacrylamide gel under the effect of electrical potential. The properties are: Stokes' radii 2.96-3.56 nm; molecular masses 42-70 kDa; net negative charge 7.2-13.5; surface charge densities 3139-4069 -esu∙˙cm^(-2); surface potentials 10.6-15.7 -mV; coefficients of friction 5.74-6.90 × 10-8 g∙˙s^(-1); and diffusion coefficients 5.76-6.94 7× 10-7 cm^2∙˙s^(-1). We found that these particles were of low stability as they underwent molecular transformation into larger particles on storage. The estimated dimensions of these particles do not support ellipsoidal shape, therefore, the most probable shape is spherical; consequently, their hydrated characteristics were estimated. We conclude that these particles have high values of negative surface charge and diffusion coefficients, and are of low stability. Their small Stokes' radii were similar to each other and they are spherical and highly hydrated.

Źródło:

Acta Biochimica Polonica; 2005, 52, 2; 515-525
0001-527X

Pojawia się w:

Acta Biochimica Polonica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 37.

Tytuł:

Comparison of soil models in the thermodynamic analysis of a submarine pipeline buried in seabed sediments

Autorzy:

Magda, W.

Powiązania:

https://bibliotekanauki.pl/articles/259219.pdf

Data publikacji:

2017

Wydawca:

Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa

Tematy:

submarine buried pipeline
seabed thermal models
shape coefficient
heat transfer coefficient
longitudinal temperature profile

Opis:

This paper deals with mathematical modelling of a seabed layer in the thermodynamic analysis of a submarine pipeline buried in seabed sediments. The existing seabed soil models: a “soil ring” and a semi-infinite soil layer are discussed in a comparative analysis of the shape factor of a surrounding soil layer. The meaning of differences in the heat transfer coefficient of a soil layer is illustrated based on a computational example of the longitudinal temperaturę profile of a -kilometer long crude oil pipeline buried in seabed sediments.

Źródło:

Polish Maritime Research; 2017, 4; 124-130
1233-2585

Pojawia się w:

Polish Maritime Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 38.

Tytuł:

Derivation of the formula for the filtration coefficient by application of Poiseuilles law in membrane transport

Autorzy:

Jarzynska, M
Pietruszka, M.

Powiązania:

https://bibliotekanauki.pl/articles/59171.pdf

Data publikacji:

2009

Wydawca:

Polskie Towarzystwo Botaniczne

Tematy:

mathematical analysis
membrane
filtration coefficient
Kedem-Katchalsky equation
viscosity coefficient
membrane transport
Poiseuille's law

Opis:

On the basis of Kedem-Katchalsky equations a mathematical analysis of volume flow (Jv) of a binary solution through a membrane (M) is presented. Two cases of transport generators have been considered: hydrostatic (Δp) as well as osmotic (Δπ) pressure difference. Based on the Poiseuille's law we derive the formula for the membrane filtration coefficient (Lp) which takes into account the membrane properties, kinetic viscosity and density of a solution flowing across the membrane. With use of this formula we have made model calculations of the filtration coefficient Lp and volume flow Jv for a polymer membrane in the case when the solutions on both sides of the membrane are mixed.

Źródło:

Acta Societatis Botanicorum Poloniae; 2009, 78, 2; 93-96
0001-6977
2083-9480

Pojawia się w:

Acta Societatis Botanicorum Poloniae

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 39.

Tytuł:

Analysis of the influence of jet-abrasive flow parameters on wheel and rail friction coefficient
Analiz stepeni vlijanija parametrov strujjno-abrazivnogo potoka na koehfficient trenija kolesa s relcom

Autorzy:

Gorbunov, N.
Kovtanets, M.
Nozhenko, V.
Prosvirova, O.

Powiązania:

https://bibliotekanauki.pl/articles/792790.pdf

Data publikacji:

2013

Wydawca:

Komisja Motoryzacji i Energetyki Rolnictwa

Tematy:

adhesion coefficient
jet-abrasive flow
computer programme
planning
railway transport
transport cost
friction coefficient

Źródło:

Teka Komisji Motoryzacji i Energetyki Rolnictwa; 2013, 13, 3
1641-7739

Pojawia się w:

Teka Komisji Motoryzacji i Energetyki Rolnictwa

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 40.

Tytuł:

Implementation of e-learning platform and the determination the effectiveness of multimedia technologies teaching and learning by applying
Wdrożenie platform e-learningowych oraz określenie skuteczności technologii multimedialnych w nauczaniu poprzez zastosowanie testów statystycznych

Autorzy:

Necsulescu, C.
Serbanescu, L.

Powiązania:

https://bibliotekanauki.pl/articles/137162.pdf

Data publikacji:

2014

Wydawca:

Uczelnia Jana Wyżykowskiego

Tematy:

platforma e-nauczania
e-learning
współczynnik asymilacji
współczynnik automatyki
współczynnik efektywności
funkcja regresji
e-learning platform
assimilation coefficient
automation coefficient
efficiency coefficient
regression function

Opis:

W artykule przedstawiono rozwiązania dotyczące poprawy i wzrostu efektywności zarządzania działalności studentów na zajęciach z użyciem narzędzi internetowych. Za pomocą tych rozwiązań studenci mogą mieć zawsze i wszędzie swobodny dostęp w informacji, takich jak: kursy, wirtualne materiały laboratoryjne, opisy badań oraz statystyki. Następnie przedstawiono wybrane wyniki badań i przykłady platform e-learningowych stosowanych w Rumunii. W eksperymencie naukowym zastosowano techniki grup równoległych (4 grupy studentów drugiego roku, 2 grupy tworzące zespół eksperymentalny, dla których były używane kursy multimedialne do procesu szkolenia, i 2 grupy kontrolne). Przeprowadzone badania potwierdziły hipotezę o pozytywnym wpływie realizacji kursów multimedialnych w procesie nauczania grup eksperymentalnych i efektywności stosowanych metod.
In this article, we presented a solution for improving and rising the management efficiency of the students’ activities for the courses in the current semester, using Web Technologies. Moreover, using this solution given by the described application, students of any faculty can have anytime and anywhere access to information such as: courses materials, virtual labs materials, marks given for partial or final tests, statistics regarding the scholar situations. Then, we presented some statistics and examples of e-learning platforms realized in Romania. In this scientific experiment we applied the technique of parallel groups which supposes the implication of 4 groups of second year students, 2 groups forming the experimental team for whom the multimedia courses for training process were used and 2 control groups for whom teaching was made in the traditional system. The application of the statistical methods of processing experimental data attested the hypotheses about the positive impact of the implementation of the multimedia courses in teaching- learning process in the experimental groups and the efficiency of the applied methods to the experimental groups, compared to traditional methods, applied to control groups.

Źródło:

Zeszyty Naukowe Dolnośląskiej Wyższej Szkoły Przedsiębiorczości i Techniki. Studia z Nauk Technicznych; 2014, 3; 53-80
2299-3355

Pojawia się w:

Zeszyty Naukowe Dolnośląskiej Wyższej Szkoły Przedsiębiorczości i Techniki. Studia z Nauk Technicznych

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 41.

Tytuł:

Kurs złotego w świetle analizy falkowej
A Wavelet Analysis of the Exchange Rate of the Zloty

Autorzy:

Bereś, Helena
Bereś, Krzysztof
Zięba, Jolanta

Powiązania:

https://bibliotekanauki.pl/articles/575476.pdf

Data publikacji:

2009-03-31

Wydawca:

Szkoła Główna Handlowa w Warszawie. Kolegium Analiz Ekonomicznych

Tematy:

wavelet analysis
currency exchange rates
statistical parameters
Hurst coefficient
gamma coefficient
Generalized Pareto Distribution (GPD)

Opis:

The paper looks at currency exchange rates through the lens of a mathematical procedure known as a wavelet analysis. The authors use two statistical parameters, the Hurst coefficient and the gamma coefficient, to determine the compliance of their method with what is called Generalized Pareto Distribution (GPD). The Hurst coefficient is a measure of the randomness of a process and shows how it changes. The gamma coefficient provides information on the dependence/independence of variables generating the process. In the case of currency exchange rates, the main variables are key economic factors and decisions made by monetary policy makers. The analysis applies to a period in the past when Poland’s exchange rate system became more flexible. Depending on changes made in the exchange rate system, the authors identified periods of a uniform exchange rate policy and the stage of a free market rate. They zeroed in on daily changes in the dollar/zloty and euro/zloty rates, in addition to other factors.

Źródło:

Gospodarka Narodowa. The Polish Journal of Economics; 2009, 230, 3; 61-88
2300-5238

Pojawia się w:

Gospodarka Narodowa. The Polish Journal of Economics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 42.

Tytuł:

Analysis of harmonics reduction methods selection for transformer substation

Autorzy:

Racewicz, Szymon
Rokicki, Mateusz

Powiązania:

https://bibliotekanauki.pl/articles/298173.pdf

Data publikacji:

2020

Wydawca:

Uniwersytet Warmińsko-Mazurski w Olsztynie

Tematy:

harmonics reduction
active filters
THD coefficient

Opis:

The article presents an investigation of the harmonic level and its possible reduction methods for one of the Michelin factory transformer substation. The substation electrical network consists of two transformers (1.6 MVA and 2.0 MVA) supplying a production line composed of several electrical equipment based on DC and AC motors. In order to investigate the harmonics level and its influence on the substation operation the measurements of the current and the load factor of the powered machines as well as the coefficients THD_u, THD_i, D_u and D_i have been performed using the 3-phase energy quality analyzer Fluke 435II and the network parameter recorder PEL103. Basing on the measurements data the four harmonics reduction methods (passive filters, active filters, 12-pulse rectifier and the Active Front End system) have been proposed and studied. For this purpose the substation electrical network has been modelled using Emerson Harmonics Estymator software. Furthermore, in order to choose the optimal solution the financial analysis of the potential investments has been performed.

Źródło:

Technical Sciences / University of Warmia and Mazury in Olsztyn; 2020, 23(1); 5-23
1505-4675
2083-4527

Pojawia się w:

Technical Sciences / University of Warmia and Mazury in Olsztyn

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 43.

Tytuł:

Research on tribological properties of dental composite materials

Autorzy:

Dziedzic, K.
Zubrzycka-Wróbel, J.
Józwik, J.
Barszcz, M.
Siwak, P.
Chałas, R.

Powiązania:

https://bibliotekanauki.pl/articles/103005.pdf

Data publikacji:

2016

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

dental materials
biotribology
friction coefficient
wear

Opis:

Dental practice today used a lot of different materials. This paper evaluates tribological and mechanical properties of two dental materials CeramX and I-Light. Tribological analysisad of samples was conducted at temperature 37°C and in the environment of artificial saliva. The wear rate was evaluated with a ball-on-disc tribotester, in accordance to ASTM G-133 norm. The counterbodies were 6-mm-in-diameter Al2 O3 steel balls. The load of 2, 10 and 20 N was applied. The tests were conducted at 0.15 m/s sliding velocity over a sliding stroke of 1000 m. The changes in the value of the following parameters were measured during the trials: friction coefficient, friction force, temperature and wear depth. After completing the tribological tests the surface of samples was carried out.

Źródło:

Advances in Science and Technology. Research Journal; 2016, 10, 32; 144-149
2299-8624

Pojawia się w:

Advances in Science and Technology. Research Journal

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 44.

Tytuł:

Nonhomogeneity of the physical-mechanical properties of soil medium composed of tertiary clays and quaternary loesses
Niejednorodność właściwości fizyczno-mechanicznych ośrodka gruntowego zbudowanego z trzeciorzędowych iłów i czwartorzędowych lessów

Autorzy:

Frankowski, Z.
Kaczyński, R.
Bogucki, A.
Woloshyn, P.

Powiązania:

https://bibliotekanauki.pl/articles/281302.pdf

Data publikacji:

1998

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

nonhomogenity
loesses
clays
coefficient of variation

Opis:

The properties of typical sois occurring in Poland and Ukraine are analysed in this paper. The Tertiary maritime clays from Krakowiec and Quaternary eolic loesses of the porosity lying within the range of 25-60% and of the laminar and skeletal microstructures, respectively, have been tested. They often constitute foundations of buildings, and therefore, their physical-mechanical parameters should be determined. The analysis of nonhomogeneity has been limited to the presentation of statistical coefficient of variation for basic parameters used in design of foundations of energeering objects. Nonhomogeneity of soils is caused by geological conditions of their origin. The results presented indicate that the tested loesses and clays from Poland and Ukraine are very similar from the viwepoint of their parameters nonhomogeneity. The parameters vary within the range below 30-40%, whereas the coefificient of variation for mechanical parameters often exceeds 100%. The coefficient of variation becomes smaller when the subsets of samples are extracted from the whole testing set. In view of engineering-geological properties of soils, for the purpose of engineering calculations one may assume that the homogeneous soils are those for which the values of coefficient of variation do not exceed the limit values for particular parameters.
W pracy przeanalizowano niejednorodność właściwości typowych gruntów występujących na terenie Polski i Ukrainy. Testowymi gruntami były trzeciorzędowe morskie iły krakowieckie i czwartorzędowe eoliczne lessy o porowatości w granicach 25-60% oraz mikrostrukturach laminarnej w iłach i szkieletowej w lessach. Badane grunty stanowią podłoże budowlane, wymagające określenia parametrów fizyczno-mechanicznych. Analiza niejednorodności zostaa ograniczona do przedstawienia wyników współczynnika statystycznego zmienności (niejednorodności) wyznaczonego dla podstawowych parametrów, wykorzystywanych podczas projektowania posadowienia obiektów inżynierskich na podłożu gruntowym. Niejednorodność gruntów jest uzasadniona genetycznie, spowodowana geologicznymi warunkami powstawania. Przedstawione wyniki wskazują, że badane lessy i iły Polski i Ukrainy pod względem niejednorodności parametrów wykazują dużą zbieżność. Zmienność parametrów gruntów jest silnie zróżnicowana. Parametry fizyczne zmieniają się poniżej 30-40%, natomiast współczynnik zmienności dla parametrów mechanicznych często przekracza 100%. Współczynnik zmienności zmniejsza się przy wydzielaniu podzbiorów z całości uzyskanych wyników. Pod wzglęgem geologiczno-inżynierskim, dla celów obliczeń projektowych, można przyjąć za jednorodne (jednorodną warstwę obliczeniową) grunty charakteryzujące się wartością współczynnika zmienności nie przekraczającą wartości granicznych dla poszczególnych parametrów gruntów.

Źródło:

Journal of Theoretical and Applied Mechanics; 1998, 3; 581-595
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 45.

Tytuł:

On uniformly convex functions

Autorzy:

Goodman, A.

Powiązania:

https://bibliotekanauki.pl/articles/1312377.pdf

Data publikacji:

1991

Wydawca:

Polska Akademia Nauk. Instytut Matematyczny PAN

Tematy:

univalent functions
convex functions
coefficient bounds

Opis:

We introduce a new class of normalized functions regular and univalent in the unit disk. These functions, called uniformly convex functions, are defined by a purely geometric property. We obtain a few theorems about this new class and we point out a number of open problems.

Źródło:

Annales Polonici Mathematici; 1991-1992, 56, 1; 87-92
0066-2216

Pojawia się w:

Annales Polonici Mathematici

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 46.

Tytuł:

Evaluation of Friction Coefficient and Adhesion Properties of Silicon Carbon Nitride Films Prepared by HWCVD

Autorzy:

Yamada, T.
Iseda, T.
Kadotani, Y.
Izumi, A.

Powiązania:

https://bibliotekanauki.pl/articles/1033523.pdf

Data publikacji:

2017-03

Wydawca:

Polska Akademia Nauk. Instytut Fizyki PAN

Tematy:

SiCN
HWCVD
friction-coefficient
adhesion strength

Opis:

We have investigated the friction-coefficient properties of silicon carbon nitride (SiCN) films deposited on stainless steel substrates and the adhesion properties of SiCN films deposited on Si(100). The SiCN films were deposited by hot-wire chemical vapor deposition using hexamethyldisilazane and ammonium. It was found that SiCN coating was able to effectively reduce the frictional coefficient of the stainless steel substrates. The adhesion strength was measured by surface-interface physical property analysis equipment (SAICAS) and was found to be 45 N/m for the as-deposited SiCN film on Si(100). Furthermore, a maximum adhesive strength of 92 N/m was obtained after treating the film for 10 min at 1000°C.

Źródło:

Acta Physica Polonica A; 2017, 131, 3; 463-466
0587-4246
1898-794X

Pojawia się w:

Acta Physica Polonica A

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 47.

Tytuł:

On some confidence intervals for population mean in case of asymmetric distributions of random variables
Estymacja przedziałowa wartości oczekiwanej asymetrycznych rozkładów zmiennych losowych

Autorzy:

Baszczyńska, Aleksandra
Pekasiewicz, Dorota

Powiązania:

https://bibliotekanauki.pl/articles/907043.pdf

Data publikacji:

2008

Wydawca:

Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego

Tematy:

confidence interval
asymmetric distribution
asymmetry coefficient

Opis:

In the paper we present some methods of interval estimation of the population mean of skewed population. We consider nonparametric estimation method where information about the value of asymmetry coefficient is used. We apply simulation methods to compare the lengths of confidence intervals obtained by the considered method and the classical one.
W pracy przedstawiono pewną metodę estymacji przedziałowej średniej dla populacji o asymetrycznym rozkładzie. Rozważano metodę nieparametryczną wykorzystującą informacje o rzeczywistej lub oszacowanej wartości współczynnika asymetrii populacji. Za pomocą metod symulacyjnych dokonano porównania rozważanej metody z metodą klasyczną poprzez analizę długości przedziałów ufności oraz analizę odsetka przedziałów pokrywających szacowany parametr.

Źródło:

Acta Universitatis Lodziensis. Folia Oeconomica; 2008, 216
0208-6018
2353-7663

Pojawia się w:

Acta Universitatis Lodziensis. Folia Oeconomica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 48.

Tytuł:

Synthetic measurement of deviation in budgetary control

Autorzy:

Dynowska, Joanna
Kes, Zdzisław

Powiązania:

https://bibliotekanauki.pl/articles/583119.pdf

Data publikacji:

2018

Wydawca:

Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu

Tematy:

budget control
Gini coefficient
convex combination

Opis:

Budget control is an important element of budgeting, which is an important management accounting tool. Hence, it is necessary to recognize the need for its development. The article presents the authors’ method of measuring the variation of budget deviations. A synthetic measure of budget differentiation can be used to assess deviation levels in the budgetary control process. The method described herein provides a deviation measure that is a weighted average of the relative and absolute deviations using a convex combination of Gini coefficients, which are used as a measure of variance. The research used data including monthly budgeted and actual costs from a thermal power plant in Poland for the years 2014 through 2016. The article is a methodological approach that fits into the current research on tools used in budgetary control. In addition, the described method is integrated into the development of work on control systems.

Źródło:

Prace Naukowe Uniwersytetu Ekonomicznego we Wrocławiu; 2018, 503; 133-142
1899-3192

Pojawia się w:

Prace Naukowe Uniwersytetu Ekonomicznego we Wrocławiu

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 49.

Tytuł:

Measurements of plasma diffusion coefficient in Pilot-PSI device using Katsumata probe

Autorzy:

Solomon, M. L.
Mihaila, I.
Anita, V.
Costin, C.
Popa, G.
van der Meiden, H.
Al, R.
van Rooij, G.
Cardozo, N. L.
Rapp, J.
Ionita, C.
Stärz, R.
Schrittwieser, R.

Powiązania:

https://bibliotekanauki.pl/articles/385269.pdf

Data publikacji:

2009

Wydawca:

Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów

Tematy:

Katsumata probe
magnetized plasma
diffusion coefficient

Opis:

Cross-field transport of particles and energy is a major issue in magnetized fusion-relevant plasmas, due to its relevance for plasma confinement. In this paper Katsumata probe measurements performed in Pilot-PSI linear magnetized plasma device are presented. The plasma diffusion coefficient in perpendicular direction to the magnetic field was estimated from the measurements.

Źródło:

Journal of Automation Mobile Robotics and Intelligent Systems; 2009, 3, 4; 160-162
1897-8649
2080-2145

Pojawia się w:

Journal of Automation Mobile Robotics and Intelligent Systems

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 50.

Tytuł:

CZY PRZEDSIĘBIORSTWO O WYSOKIEJ WARTOŚCI WSPÓŁCZYNNIKA SKUPIENIA MA NISKI STOPIEŃ RELACJI W SIECI POWIĄZAŃ WSPÓLNĄ DYREKCJĄ NA POLSKIM RYNKU KAPITAŁOWYM?
Do companies with high clustering coefficient have low degree in the network of interlocking directorates on the Polish capital market?

Autorzy:

Siudak, Dariusz

Powiązania:

https://bibliotekanauki.pl/articles/950631.pdf

Data publikacji:

2015

Wydawca:

Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu

Tematy:

network
clustering coefficient
degree
interlocking directorate

Opis:

The article looks at the relation of the clustering coefficient and degree in the network of interlocking directorates. The study covered 479 enterprises which degree is over 1 out of 902 companies listed on the main market at the Warsaw Stock Exchange and on the NewConnect at the end of 2014. The relation of the clustering coefficient and degree was assessed using the one-way analysis of variance (ANOVA) and a comparison of two network clustering coefficients, (1) in the sense of Watts-Strogatz (CCWS) and in the sense of transitivity (C). The analysis led to the conclusion that a company with a high clustering coefficient has low degree in the board network on the Polish capital market.

Źródło:

Financial Sciences. Nauki o Finansach; 2015, 3(24); 150-159
2080-5993
2449-9811

Pojawia się w:

Financial Sciences. Nauki o Finansach

Dostawca treści:

Biblioteka Nauki

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