1,012 research outputs found
Determination of the time-dependent reaction coefficient and the heat flux in a nonlinear inverse heat conduction problem
Diffusion processes with reaction generated by a nonlinear source are commonly encountered in practical applications related to ignition, pyrolysis and polymerization. In such processes, determining the intensity of reaction in time is of crucial importance for control and monitoring purposes. Therefore, this paper is devoted to such an identification problem of determining the time-dependent coefficient of a nonlinear heat source together with the unknown heat flux at an inaccessible boundary of a one-dimensional slab from temperature measurements at two sensor locations in the context of nonlinear transient heat conduction. Local existence and uniqueness results for the inverse coefficient problem are proved when the first three derivatives of the nonlinear source term are Lipschitz continuous functions. Furthermore, the conjugate gradient method (CGM) for separately reconstructing the reaction coefficient and the heat flux is developed. The ill-posedness is overcome by using the discrepancy principle to stop the iteration procedure of CGM when the input data is contaminated with noise. Numerical results show that the inverse solutions are accurate and stable
A way to increase the efficiency of straw spreaders
The use of high-quality bedding is important for the health of farm animals. Straw is an excellent material for bedding, but before use it must be crushed to particles no larger than 100 mm, which will achieve optimal moisture and gas absorption capacity, as well as simplify the mechanization of application and cleaning. Centrifugal spreaders, belt conveyors and blow spreaders are used to apply litter. The paper considers some types of litter spreaders used in farms in the north-West. It is revealed that, along with the obvious advantages, the considered machines have disadvantages. The main one is the uneven distribution of the litter when it is applied. This, in turn, leads to the need for manual labor when leveling the straw layer after its introduction in a mechanized way. A new design of the spreader-blower is proposed aimed at ensuring the uniformity of the litter layer during application. The calculation of optimization of some parameters of the new installation is described. In addition to the calculated value of the straw particle velocity, the angle of inclination of the front wall of the discharge duct is also determined
A trapped-ion local field probe
We introduce a measurement scheme that utilizes a single ion as a local field
probe. The ion is confined in a segmented Paul trap and shuttled around to
reach different probing sites. By the use of a single atom probe, it becomes
possible characterizing fields with spatial resolution of a few nm within an
extensive region of millimeters. We demonstrate the scheme by accurately
investigating the electric fields providing the confinement for the ion. For
this we present all theoretical and practical methods necessary to generate
these potentials. We find sub-percent agreement between measured and calculated
electric field values
Action at a distance as a full-value solution of Maxwell equations: basis and application of separated potential's method
The inadequacy of Li\'{e}nard-Wiechert potentials is demonstrated as one of
the examples related to the inconsistency of the conventional classical
electrodynamics. The insufficiency of the Faraday-Maxwell concept to describe
the whole electromagnetic phenomena and the incompleteness of a set of
solutions of Maxwell equations are discussed and mathematically proved. Reasons
of the introduction of the so-called ``electrodynamics dualism concept"
(simultaneous coexistence of instantaneous Newton long-range and
Faraday-Maxwell short-range interactions) have been displayed. It is strictly
shown that the new concept presents itself as the direct consequence of the
complete set of Maxwell equations and makes it possible to consider classical
electrodynamics as a self-consistent and complete theory, devoid of inward
contradictions. In the framework of the new approach, all main concepts of
classical electrodynamics are reconsidered. In particular, a limited class of
motion is revealed when accelerated charges do not radiate electromagnetic
field.Comment: ReVTeX file, 24pp. Small corrections which do not have influence
results of the paper. Journal reference is adde
NUMERICAL SIMULATION ОF THE WORKING PROCESSES IN THE COMBUSTION CHAMBERS OF GAS TURBINE ENGINES TAKING INTO ACCOUNT THE HEAT EXCHANGE WITH THE WALLS
Computational analysis using modern CFD packages of the workflow parameters in the combustion chambers of gas turbine engines taking into account the conjugate heat exchange
Estimation method for determining surface film conductance during cooling of fish packages.
This paper presents an alternative method for determining the surface film conductance of an infinite fish slab subjected to the cooling process. Many methods have been published, but their solutions have inherent appreciable inaccuracy and limitations. The present authors used the temperature histories of five locations within a slab sample of fish, obtained by the experimental investigation part of this work, along with the inverse heat conduction problem (IHCP) technique to develop a correlation for variable surface film conductance. When the above correlation was used for temperature predictions, the predicted and experimentally measured temperature distribution profiles were compared numerically. Better agreement than that implemented by other investigators was achieved. This revealed the accuracy and superiority of the present method, and the limitations of other methods are overcome in this method
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