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Wyszukujesz frazę "temperature modulation" wg kryterium: Wszystkie pola


Tytuł:
Weakly nonlinear oscillatory convection in a viscoelastic fluid saturated porous medium with throughflow and temperature modulation
Autorzy:
Kiran, P.
Narasimhulu, Y.
Manjula, S. H.
Tematy:
przepływ
modulacja temperatury
teoria nieliniowa
model Ginzburga-Landaua
throughflow
temperature modulation
weak nonlinear theory
complex Ginzburg-Landau model
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Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/265198.pdf  Link otwiera się w nowym oknie
Opis:
The effect of vertical throughfow and temperature modulation on a viscoelastic fluid saturated porous medium has been investigated. The amplitudes of temperature modulation at the lower and upper surfaces are considered to be very small and the disturbances are expanded in terms of power series of amplitude of convection. A weak nonlinear stability analysis has been performed for the oscillatory mode of convection, and heat transport in terms of the Nusselt number, which is governed by the non autonomous complex Ginzburg- Landau equation, is calculated. The effect of vertical through flow is found to stabilize the system irrespective of the direction of through flow in the case of permeable boundary conditions. The time relaxation has a destabilizing effect, while the time retardation parameter has a stabilizing effect on the system. The effects of amplitude and frequency of modulation on heat transport have been analyzed and depicted graphically. The study shows that the heat transport can be controlled effectively by a mechanism that is external to the system. Further, it is also found that heat transfer is more in oscillatory mode of convection rather than in stationary mode of convection.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrogen Detection With a Gas Sensor Array – Processing and Recognition of Dynamic Responses Using Neural Networks
Autorzy:
Gwiżdż, P.
Brudnik, A.
Zakrzewska, K.
Tematy:
gas sensor
sensor array
temperature modulation
dynamic response
feature extraction
neural networks
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Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/221723.pdf  Link otwiera się w nowym oknie
Opis:
An array consisting of four commercial gas sensors with target specifications for hydrocarbons, ammonia, alcohol, explosive gases has been constructed and tested. The sensors in the array operate in the dynamic mode upon the temperature modulation from 350°C to 500°C. Changes in the sensor operating temperature lead to distinct resistance responses affected by the gas type, its concentration and the humidity level. The measurements are performed upon various hydrogen (17-3000 ppm), methane (167-3000 ppm) and propane (167-3000 ppm) concentrations at relative humidity levels of 0-75%RH. The measured dynamic response signals are further processed with the Discrete Fourier Transform. Absolute values of the dc component and the first five harmonics of each sensor are analysed by a feed-forward back-propagation neural network. The ultimate aim of this research is to achieve a reliable hydrogen detection despite an interference of the humidity and residual gases.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth and properties of ZnO films grown using pa-movpe with DMZn and N2O
Autorzy:
Nakano, T.
Nishimoto, K.
Sumiya, M.
Fuke, S.
Tematy:
ZnO
PA-MOVPE
epitaxial growth
DMZn
N2O
temperature modulation growth
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Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Powiązania:
https://bibliotekanauki.pl/articles/385163.pdf  Link otwiera się w nowym oknie
Opis:
ZnO films were grown by plasma-assisted metal organic vapor phase epitaxy (PA-MOVPE) using dimethylzinc (DMZn) and N O gases. The crystallinity and surface morphology of ZnO films were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The crystallinity of ZnO improved (a) when the N2O flow rate was increased, because vapor phase reaction was suppressed while surface migration was enhanced, and (b) when the growth temperature was increased, because surface diffusion was enhanced. In the PA-MOVPE method with N2O gases and DMZn, both the N2O flow rate and crystal growth temperature strongly affected the crystallinity of ZnO films.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of modulation on heat transport by a weakly nonlinear thermal instability in the presence of applied magnetic field and internal heating
Autorzy:
Manjula, S. H.
Kiran, Palle
Narsimlu, G.
Roslan, R.
Tematy:
modulacja
pole magnetyczne
ogrzewanie
Ginzburg-Landau equation
temperature modulation
applied magnetic field
internal heating
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Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/1839705.pdf  Link otwiera się w nowym oknie
Opis:
The present paper deals with a weakly nonlinear stability problem under an imposed time-periodic thermal modulation. The temperature has two parts: a constant part and an externally imposed time-dependent part. We focus on stationary convection using the slow time scale and quantify convective amplitude through the real Ginzburg-Landau equation (GLE). We have used the classical fourth order Runge-Kutta method to solve the real Ginzburg-Landau equation. The effect of various parameters on heat transport is discussed through GLE. It is found that heat transport analysis is controlled by suitably adjusting the frequency and amplitude of modulation. The applied magnetic field (effect of Ha) is to diminish the heat transfer in the system. Three different types of modulations thermal, gravity, and magnetic field have been compared. It is concluded that thermal modulation is more effective than gravity and magnetic modulation. The magnetic modulation stabilizes more and gravity modulation stabilizes partially than thermal modulation.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A preliminary analysis of spray booth temperature control using PWM modulation with dynamic trigger period
Autorzy:
Jaszczak, S.
Nikończuk, P.
Tematy:
spray booth
temperature control
PWM control
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Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Powiązania:
https://bibliotekanauki.pl/articles/114563.pdf  Link otwiera się w nowym oknie
Opis:
The authors present a concept of the temperature control system for a spray booth equipped with a single burner. The control system uses PWM modulation with dynamic trigger time periods. The paper presents the results of temperature control simulations for different conditions of external air temperature as well as the analysis of external air temperature and trigger time period impact on temperature fluctuation amplitudes inside the spray booth. A dynamic trigger period will minimize the number of burner ignitions with acceptable fluctuation amplitudes of temperature. The minimization of the number of burner ignitions will increase the life time of a burner and decrease the fuel consumption used to start a burner.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of the pulse width modulation on the temperature distribution in the armature of a solenoid valve
Autorzy:
Goraj, R.
Tematy:
solenoid valve
armature
inductive power
PWM
temperature
elektrozawór
armatura
zasilanie indukcyjne
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Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/266168.pdf  Link otwiera się w nowym oknie
Opis:
In order to estimate the inductive power set in the armature of the high-speed solenoid valve (HSV) during the open loop control (OLC) using pulse width modulation (PWM) an analytical explicit formula has been derived. The simplifications taken both in the geometry and in the physical behavior of the HSV were described. The inductive power was calculated for different boundary conditions and shown as a function of the frequency of the coil current. The power set in the armature was used as an input to the thermal calculation. The thermal calculation had an objective to estimate the time dependent temperature distribution in the armature of the HSV. All the derivation steps were presented and the influence of different boundary conditions was shown and discussed. The increase of the temperature during the heating with inductive power has been evaluated both in the core and on the side surface of the HSV.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fiber Bragg grating-based high temperature sensor and its low cost interrogation system with enhanced resolution
Autorzy:
Mamidi, V R
Kamineni, S
Ravinuthala, L N S P
Madhuvarasu, S S
Thumu, V R
Pachava, V R
Putha, K
Tematy:
fiber Bragg grating (FBG)
long period grating
fiber optic temperature sensor
optical intensity modulation
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/949414.pdf  Link otwiera się w nowym oknie
Opis:
A fiber Brag grating-based high temperature sensor together with a low cost, high speed and compact size interrogation system using a long period grating was designed, developed and tested. The designed sensor measures the temperature from room temperature to 550 °C. The sensor head was configured by encapsulating an fiber Brag grating (type-I) of Bragg resonance wavelength at 1552.88 nm in a capillary tube made of copper. Long period grating with peak transmission loss at 1550 nm was employed to convert the wavelength information from fiber Brag grating into an intensity modulated signal. Temperature related optical intensity information was again converted into its equivalent electrical signal by using a photodiode. The achieved resolution of the sensor was found to be 0.5 °C.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Discussion around IR material and structure issues to go toward high performance small pixel pitch IR HOT FPAs
Autorzy:
Gravrand, Olivier
Baier, Nicolas
Ferron, Alexandre
Rochette, Florent
Lobre, Clément
Bertoz, Jocelyn
Rubaldo, Laurent
Tematy:
mid-wave infrared
focal plane array
high operating temperature
small pitch
modulation transfer function
finite element method
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Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Powiązania:
https://bibliotekanauki.pl/articles/2204207.pdf  Link otwiera się w nowym oknie
Opis:
In the last decade, infrared imaging detectors trend has gone for smaller pixels and larger formats. Most of the time, this scaling is carried out at a given total sensitive area for a single focal plane array. As an example, QVGA 30 μm pitch and VGA 15 μm pitch exhibit exactly the same sensitive area. SXGA 10 μm pitch tends to be very similar, as well. This increase in format is beneficial to image resolution. However, this scaling to even smaller pixels raises questions because the pixel size becomes similar to the IR wavelength, but also to the typical transport dimensions in the absorbing material. Hence, maintaining resolution for such small pixel pitches requires a good control of the modulation transfer function and quantum efficiency of the array, while reducing the pixel size. This might not be obtained just by scaling the pixel dimensions. As an example, bulk planar structures suffer from excessive lateral diffusion length inducing pixel-to-pixel cross talk and thus degrading the modulation transfer function. Transport anisotropy in some type II superlattice structures might also be an issue for the diffusion modulation transfer function. On the other side, mesa structures might minimize cross talk by physically separating pixels, but also tend to degrade the quantum efficiency due to a non-negligible pixel fill factor shrinking down the pixel size. This paper discusses those issues, taking into account different material systems and structures, in the perspective of the expected future pixel pitch infrared focal plane arrays.
Dostawca treści:
Biblioteka Nauki
Artykuł

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