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Wyświetlanie 1-15 z 19
Tytuł:
Impact of Clothing Size on Thermal Insulation – A Pilot Study
Autorzy:
Młynarczyk, Magdalena
Orysiak, Joanna
Jankowski, Jarosław
Prus, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/24200936.pdf
Data publikacji:
2023
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
thermal insulation
air gap
air volume
3D scanning
Opis:
Thermal insulation may be influenced by the size of clothing and thus the volume of air gaps. The aim of this study was to determine the relationship between the size of outer wear clothing, and thus the indirect fit (the volume and size of air gaps), and thermal insulation in static and dynamic conditions. A set of underwear and two types of outerwear for workers of the energy sector and the chemical industry were selected for the study. Results showed that the value of thermal insulation (regardless of the type of outerwear) first increased with increasing clothing size.
Źródło:
Fibres & Textiles in Eastern Europe; 2023, 31, 1; 1--8
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of sound absorption performance of acoustic absorbers made of fibrous materials
Autorzy:
Meissner, Mirosław
Zieliński, Tomasz G.
Powiązania:
https://bibliotekanauki.pl/articles/2202433.pdf
Data publikacji:
2022
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
sound absorption
multi-layer absorber
surface impedance
fibrous materials
air gap
chłonność akustyczna
wielowarstwowy pochłaniacz dźwięku
materiały włókniste
szczelina powietrzna
Opis:
Absorbing properties of multi-layer acoustic absorbers were modeled using the impedance translation theorem and the Garai and Pompoli empirical model, which enables a determination of the characteristic impedance and propagation constant of fibrous sound-absorbing materials. The theoretical model was applied to the computational study of performance of single-layer acoustic absorber backed by a hard wall and the absorber consisting of one layer of absorbing material and an air gap between the rear of the material and a hard back wall. Simulation results have shown that a high thickness of absorbing material may cause wavy changes in the frequency relationship of the normal and random incidence absorption coefficients. It was also found that this effect is particularly noticeable for acoustic absorbers with a large thickness of air gap between the absorbing material and a hard back wall.
Źródło:
Vibrations in Physical Systems; 2022, 33, 2; art. no. 2022205
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Obliczenia wartości zastępczej rezystancji cieplnej szczeliny powietrznej w wirnikowych maszynach elektrycznych
Calculations of thermal resistance of an air gap in rotating electrical machines
Autorzy:
Opach, Szczepan
Powiązania:
https://bibliotekanauki.pl/articles/2142531.pdf
Data publikacji:
2022
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
ANSYS 2021 R2
rezystancja cieplna szczeliny powietrznej
MES
thermal resistance of an air gap
FEM
Opis:
Artykuł przedstawia analizę zagadnienia transferu i wymiany ciepła między stojanem a wirnikiem maszyny elektrycznej, poprzez szczelinę powietrzną. Jest to zagadnienie kluczowe z punktu widzenia poprawności opracowania modeli cieplnych maszyn elektrycznych. W artykule przedstawiono jedną, wśród wielu propozycji analitycznego rozwiązania problemu, pojawiających się w licznych artykułach naukowych. Weryfikację podejścia analitycznego przeprowadzono na autorskim modelu obliczeniowym, zbudowanym i rozwiązanym w oparciu o MES w systemie ANSYS Fluent.
The article presents an analysis of the issue of heat transfer and exchange between the stator and the rotor of the electric machine through the air gap. This is a key issue for the correct preparation of CFD models of electrical machines. The article presents one, among many proposals for an analytical solution to the problem, appearing in numerous scientific articles. The verification of the analytical approach was carried out on the own computational model, built and solved on the basis of FEM in the ANSYS Fluent system.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2022, 3, 1 (127); 101--105
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Investigation of the Air Gap Distribution of Jackets with Different Fits and its Influence on Human Temperature
Autorzy:
Awais, Muhammad
Krzywinski, Sybille
Kyosev, Yordan
Powiązania:
https://bibliotekanauki.pl/articles/2056297.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
thermal simulation
3D fit simulation of clothing
3D scanning
air gap
clothing fit
thermo-physiological model
Opis:
The air gaps underneath clothing have a great influence on the thermal regulation of the human body. The distribution of the air gaps depends on the shape of the human body as well as on clothing style, fit, and deformation properties. This paper reports on the influence of clothing fit on thermophysiological parameters of the human body through thermal simulation. Four different fits of jacket and a test person were considered for the investigation and for simulation purposes. The results of the simulation concluded that different thermal regulations of the human body were exhibited for different fits of the jacket, which is due to distinct air gaps between the human body and clothing for each fit of the jacket. This research work presents a fast method to predict the influence of clothing fit on thermal comfort, which is usually studied by a time-consuming, laborious method – the wear trial.
Źródło:
Fibres & Textiles in Eastern Europe; 2021, 6 (150); 77--86
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance analysis and comparison of PMSM with concentrated winding and distributed winding
Autorzy:
Qiu, Hongbo
Zhang, Yong
Yang, Cunxiang
Yi, Ran
Powiązania:
https://bibliotekanauki.pl/articles/141179.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
air-gap flux density
cogging torque
concentrated winding
distributed winding
efficiency
loss
PMSM
Opis:
The concentrated winding (CW) is obviously different from the traditional distributed winding (DW) in the arrangement of windings and the calculation of winding factors, which will inevitably lead to different performances of the permanent magnet synchronous motor (PMSM). In order to analyze the differences between the CW and the DW in the performance, a 3 kW, 1500 r/min PMSM is taken as an example to establish a 2-D finite element model. The correctness of the model is verified by comparing experimental data and calculated data. Firstly, the finite element method (FEM) is used to calculate the electromagnetic field of the PMSM, and the performance parameters of the PMSM are obtained. On this basis, the influences of the two winding structures on the performance are quantitatively analyzed, and the differences between the two winding structures on the performance of the PMSM will be determined. Finally, the differences of efficiency between the two winding structures are obtained. In addition, the influences of the winding structures on eddy current loss are further studied, and the mechanism of eddy current loss is revealed by studying the eddy current density. The analysis of this paper provides reference and practical value for the optimization design of the PMSM.
Źródło:
Archives of Electrical Engineering; 2020, 69, 2; 303-317
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design of a rotor with a starter-generator integrated into an aero car
Autorzy:
Wu, Zaixin
Yu, Ruiguang
Powiązania:
https://bibliotekanauki.pl/articles/141579.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aero motor
air-gap flux density
axial segmentation
electromagnetic and heat flux coupling
Halbach array structure
Opis:
The Halbach array structure rotor of the aero motor can satisfy the requirements of high power density and high air-gap flux for aeronautical motors. The size parameters of the rotor are determined by the power rating of the motor based on an analytic method. Producing a Halbach array structure is difficult. Comparison and analysis of the structure of the aero motor showthat the overall structure of the rotor adopts a three-axial-section classic Halbach-array hollow structure, and the rotor magnetic steel adopts a discrete structure of 4 blocks per pole and a single 45◦ magnetisation mode, which reduces the processing difficulty of the rotor magnetic steel. The finite element method was used to analyse the magnetic flux density distribution of the aeronautical motor under various working conditions. The results show that the motor can produce uniform air-gap flux density at various working conditions and present good sinusoidal periodicity. Furthermore, the axial segment did not produce obvious magnetic flux leakage. Finally, considering the eddy current loss of the stator under the rated power-generation condition with high-frequency magnetic field, we conducted coupling analysis of electromagnetic and heat flows to verify that the thermal characteristics of the rotor magnetic steel material could meet the requirements for the aero motor.
Źródło:
Archives of Electrical Engineering; 2019, 68, 2; 357-371
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of mineral surface energy using impact of rough topography
Autorzy:
Can, Muhammed Fatih
Çiftçi, Caner
Powiązania:
https://bibliotekanauki.pl/articles/109996.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
micro-nano roughness
natural stones
surface energy
air gap
Opis:
While some of the studies on the functionalization of surfaces are still in theoretical phase, it is not possible to apply them on natural surfaces which already contain some irregularities. However, progress can be made with a mineral having significant purity, crystal homogeneity, and controllable surface workability for surface treatment operations. Therefore, in this study the effects of roughness on the surface energies of natural stones were investigated by selecting a sample with a distinctive color and metamorphic origin from Mugla, Turkey. First, sample surfaces were prepared using a polishing line with five different abrasives. Three-dimensional surface scans were then performed with ZYGONewView7100 optical-profilometer and ParkSystemAFM to identify the 3D roughness of the surfaces on two different scales (micro and nano) with SPIP-software. The micro average heights (S) of the produced surfaces ranged between 0.423-1.127 µm, nano-scale 0.0806-0.173 µm, while the surface roughness ratio (Sdr) between 33.7%-40.1%, and nano-scale 5.19%-18.5%. The contact angles of the samples were measured in the presence of pure water, formamide, and diiodomethane using AttensionTheta-tensiometer. Changes in surface energy were followed by Van Oss, Good-Chaudrey approach. Young, Wenzel, Cassie-Baxter contact angle theories were tested within these calculations. It was revealed that the inconsistency in solid phase energy could not be determined at this stage, but it could be regulated by modifying the Cassie-Baxter approach. Furthermore, the percentage of air packs likely to be below the water droplet not foreseen by the previous studies was calculated as 26% up to 35% air gap on the solid/water interface.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 4; 1002-1013
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Field investigation in the detonation behavior of emulsion explosive column induced with air gaps
Autorzy:
Balakrishnan, Vineeth
Pradhan, Manoj
Dhekne, P. Y.
Powiązania:
https://bibliotekanauki.pl/articles/972340.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Wydział Geoinżynierii, Górnictwa i Geologii. Instytut Górnictwa
Tematy:
velocity of detonation
VOD
site mixed emulsion
SME
distributed spherical air gap
DAG
blasting
Opis:
In blasting of soft to medium hard rock, the problem of high density resulting in excessive utilization of emulsion explosive is well known. The authors have conducted some experimental blasts to delve into the detonation behavior of conventional blasting and various other explosive consumption reduction techniques which induce air gaps using plastic tubes, plastic bottles or plastic balls in the explosive column. Resistance wire technique is used for gauging in-hole continuous velocity of detonation. The VOD varies from 5321.6 m/s to 4544.2 m/s and from 5123.4 m/s to 4274.2 m/s in conventional site mixed emulsion column and distributed spherical air gap column respectively. The detonation behavior is stable and similar in both these cases. While using plastic bottles or plastic tubes as air gaps, the VOD is fluctuating from 4636.3 m/s to 3268.4 m/s and from 4935.9 m/s to 3362.8 m/s respectively with a collapse of about 12 % from the average VOD of conventional SME column. The VOD falls abruptly when the detonation wave encounters large air gaps but it is successfully travelling through the air gaps making the detonation behavior more capricious.
Źródło:
Mining Science; 2019, 26; 55-68
2300-9586
2353-5423
Pojawia się w:
Mining Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reduction of Fringing-Effect in Inductors by Quasi-Distributed-Gap Method
Autorzy:
Kasikowski, Rafał
Powiązania:
https://bibliotekanauki.pl/articles/114525.pdf
Data publikacji:
2019
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
fringing effect
inductors
fringing-effect factor
quasi-distributed air gap
IR thermography
Opis:
The fringing-field phenomenon can have a significant impact on the key performance parameters of magnetic components with an air gap. The fringing magnetic flux at the air gap has an effect on a component’s inductance, power loss and temperature distribution in copper windings. The induced excess eddy currents in the windings due to the fringing effect cause localized heating and reduce the overall efficiency of power conversion. This effect can be analysed by infra-red thermography to demonstrate the potential hazards of designing magnetic components with an air gap. Design engineers are frequently forced to design around the problem by employing a number of available techniques. The quasi-distributed-gap technique combats the issue at the origin as it essentially constrains the fringing magnetic flux at the downsized air gaps to their immediate vicinity. The selection of the length of the individual air gaps as well as their placement is not straightforward, as the phenomenon is a function of the air gap length and geometry. The resulting inductance of the component has to be the same or at least comparable to the original value in order to maintain the operating conditions of the application which the component is part of. This paper examines the effects of splitting a discrete air gap on the electromagnetic and thermal properties of inductors and presents a method to aid the design of quasi-distributed-gap inductors based on finite-element simulations as well as measurements. An analytic expression, which closely approximates the required length of quasi-distributed gaps, is developed.
Źródło:
Measurement Automation Monitoring; 2019, 65, 2; 48-51
2450-2855
Pojawia się w:
Measurement Automation Monitoring
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computer Simulation of the Solidification Process Including Air Gap Formation
Autorzy:
Skrzypczak, T.
Węgrzyn-Skrzypczak, E.
Sowa, L.
Powiązania:
https://bibliotekanauki.pl/articles/383120.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
solidification process
computer simulation
finite element method
multimesh approach
air gap
proces krzepnięcia
symulacja komputerowa
metoda elementów skończonych
podejście wielowymiarowe
szczelina powietrzna
Opis:
The paper presents an approach of numerical modelling of alloy solidification in permanent mold and transient heat transport between the casting and the mold in two-dimensional space. The gap of time-dependent width called "air gap", filled with heat conducting gaseous medium is included in the model. The coefficient of thermal conductivity of the gas filling the space between the casting and the mold is small enough to introduce significant thermal resistance into the heat transport process. The mathematical model of heat transport is based on the partial differential equation of heat conduction written independently for the solidifying region and the mold. Appropriate solidification model based on the latent heat of solidification is also included in the mathematical description. These equations are supplemented by appropriate initial and boundary conditions. The formation process of air gap depends on the thermal deformations of the mold and the casting. The numerical model is based on the finite element method (FEM) with independent spatial discretization of interacting regions. It results in multi-mesh problem because the considered regions are disconnected.
Źródło:
Archives of Foundry Engineering; 2017, 17, 4; 147-150
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of different rotor magnetic circuit structure on the performance of permanent magnet synchronous motor
Autorzy:
Qiu, H.
Yu, W.
YANG, C.
Yi, R.
Powiązania:
https://bibliotekanauki.pl/articles/141061.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
air gap flux density
cogging torque
magnetic circuit structure
overload capacity
permanent magnet synchronous motor
Opis:
In order to compare the performance difference of the permanent magnet synchronous motors (PMSM) with different rotor structure, two kinds of rotor magnetic circuit structure with surface-mounted radial excitation and tangential excitation are designed respectively. By comparing and analyzing the results, the difference of the motor performance was determined. Firstly, based on the finite element method (FEM), the motor electromagnetic field performance was studied, and the magnetic field distribution of the different magnetic circuit structure was obtained. The influence mechanism of the different magnetic circuit structure on the air gap flux density was obtained by using the Fourier theory. Secondly, the cogging torque, output torque and overload capacity of the PMSM with different rotor structure were studied. The effect mechanism of the different rotor structure on the motor output property difference was obtained. The motor prototype with two kinds of rotor structure was manufactured, and the experimental study was carried out. By comparing the experimental data and simulation data, the correctness of the research is verified. This paper lays a foundation for the research on the performance of the PMSM with different magnetic circuit structure.
Źródło:
Archives of Electrical Engineering; 2017, 66, 3; 583-594
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on the influence of driving harmonic on electromagnetic field and temperature field of permanent magnet synchronous motor
Autorzy:
Qiu, H.
Yu, W.
Li, Y.
Yang, C.
Powiązania:
https://bibliotekanauki.pl/articles/141535.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
air gap flux density
eddy current loss
harmonic
magnetic field decoupling
torque ripple
Opis:
At present, the drivers with different control methods are used in most of permanent magnet synchronous motors (PMSM). A current outputted by a driver contains a large number of harmonics that will cause the PMSM torque ripple, winding heating and rotor temperature rise too large and so on. In this paper, in order to determine the influence of the current harmonics on the motor performance, different harmonic currents were injected into the motor armature. Firstly, in order to study the influence of the current harmonic on the motor magnetic field, a novel decoupling method of the motor magnetic field was proposed. On this basis, the difference of harmonic content in an air gap magnetic field was studied, and the influence of a harmonic current on the air gap flux density was obtained. Secondly, by comparing the fluctuation of the motor torque in the fundamental and different harmonic currents, the influence of harmonic on a motor torque ripple was determined. Then, the influence of different current harmonics on the eddy current loss of the motor was compared and analyzed, and the influence of the drive harmonic on the eddy current loss was obtained. Finally, by using a finite element method (FEM), the motor temperature distribution with different harmonics was obtained.
Źródło:
Archives of Electrical Engineering; 2017, 66, 2; 295-312
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effects of Trunk Cavity and Air-Gaps in the Acoustic Response of a Passenger Vehicle
Autorzy:
Oktav, A.
Powiązania:
https://bibliotekanauki.pl/articles/950216.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
acoustic coupling
acoustic eigenfrequencies
acoustic modes
acoustic response
air-gap
cabin cavity
Helmholtz resonator
passenger vehicle
trunk cavity
wave number
Opis:
The effects of additional cavities and air-gaps in the acoustic response of a passenger vehicle are investigated. It is observed that the cabin cavity and the trunk cavity of the passenger vehicle are connected through an aperture in the rear seat. In the trunk cavity of the vehicle, there are two more air-gaps which are designed as countermeasures to trunk lid slam noise. It is established that acoustic modes and acoustic eigenfrequencies of the vehicle are altered through the trunk cavity and its air-gaps. To develop an analytical solution, the actual acoustic cavity is simplified into a rectangular shape. In the analytical solution, the coupling of trunk and cabin cavities is considered. It is shown that the computational analysis results match well with the results of the analytical solution proposed. Further, the resonator effect of air-gaps present in the trunk cavity is examined.
Źródło:
Archives of Acoustics; 2017, 42, 3; 433-440
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental analysis of linear induction motor under variable voltage variable frequency (VVVF) power supply
Autorzy:
Wakode, P. D.
Tariq, M.
Bhattacharya, T. K.
Powiązania:
https://bibliotekanauki.pl/articles/136237.pdf
Data publikacji:
2016
Wydawca:
EEEIC International Barbara Leonowicz Szabłowska
Tematy:
Linear Induction Motor
Variable Voltage Variable Frequency
experimental
air gap flux density
Opis:
This paper presents the complete analysis of Linear Induction Motor (LIM) under VVVF. The complete variation of LIM air gap flux under ‘blocked Linor’ condition and starting force is analyzed and presented when LIM is given VVVF supply. The analysis of this data is important in further understanding of the equivalent circuit parameters of LIM and to study the magnetic circuit of LIM. The variation of these parameters is important to know the LIM response at different frequencies. The simulation and application of different control strategies such as vector control thus becomes quite easy to apply and understand motor’s response under such strategy of control.
Źródło:
Transactions on Environment and Electrical Engineering; 2016, 1, 2; 18-24
2450-5730
Pojawia się w:
Transactions on Environment and Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solution of the Pure Metals Solidification Problem by Involving the Material Shrinkage and the Air-Gap Between Material and Mold
Autorzy:
Matlak, J.
Słota, D.
Powiązania:
https://bibliotekanauki.pl/articles/381022.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
solidification process
air-gap
Stefan problem
metal shrinkage
proces krzepnięcia
szczelina powietrzna
problem Stefana
skurcz stopu
Opis:
In this paper we describe an algorithm for solving the pure metals solidification problem by involving the metal shrinkage and air-gap between material and mold. In this algorithm we use the finite element method supplemented by the procedures allowing to define the position of the moving interface and the change of the material size associated with the shrinkage. We present also an example illustrating the precision of presented method.
Źródło:
Archives of Foundry Engineering; 2015, 15, 3 spec.; 47-52
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 19

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