scholarly journals Calculation improvement of no-load stray losses in induction motors with experimental validation

2015 ◽  
Vol 12 (3) ◽  
pp. 303-320
Author(s):  
Miloje Kostic
Keyword(s):  
High Frequency ◽  
Experimental Validation ◽  
Air Gap ◽  
New Classification ◽  
Iron Losses ◽  
Surface Iron ◽  
Space Harmonics ◽  
Rotor Cage

On the basis of the known fact that all air gap main flux density variations are enclosed by permeance slot harmonics, only one component of stray losses in rotor (stator) iron is considered in the new classification, instead of 2 components: rotor (stator) pulsation iron losses, and rotor (stator) surface iron losses. No-load rotor cage (high-frequency) stray losses are usually calculated. No-load stray losses are caused by the existence of space harmonics: the air-gap slot permeance harmonics and the harmonics produced by no-load MMF harmonics. The second result is the proof that the corresponding components of stray losses can be calculated separately for the mentioned kind of harmonics. Determination of the depth of flux penetration and calculations of high frequency iron losses are improved. On the basis of experimental validation, it is proved that the new classification of no-load stray losses and the proposed method for the calculation of the total value is sufficiently accurate.

A METHOD FOR THE DETERMINATION OF THE INDEX OF REFRACTION OF THIN TRANSPARENT FILMS

1948 ◽  
Vol 26a (4) ◽  
pp. 230-235 ◽  
Author(s):  
R. W. Stewart
Keyword(s):  
Thin Films ◽  
High Frequency ◽  
Air Gap ◽  
Index Of Refraction ◽  
Transparent Films ◽  
High Frequency Discharge ◽  
Discharge Tubes ◽  
Set Up ◽  
Fringe System

The index of refraction of thin films deposited on an optical flat is obtained by comparison of the fringe system set up in the film with that in the air gap between the film and another optical flat. The use of the method is illustrated by application to films produced in high frequency discharge tubes. Films produced in Pyrex glass and quartz tubes are shown to be silica in the form of cristobalite. Films produced in polystyrene tubes prove to have an index of refraction that is very low and is a function of the thickness.

DETERMINATION OF THE INFLUENCE OF STRUCTURAL ELEMENTS ON ACOUSTIC EFFICIENCY AND BACK PRESSURE IN EXHAUST AND SUCTION NOISE SILENCERS

Akustika ◽  
2021 ◽  
pp. 210-216
Author(s):  
Nickolay Ivanov ◽  
Aleksandr Shashurin ◽  
Aleksandr Burakov
Keyword(s):  
Structural Design ◽  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Back Pressure ◽  
Noise Generation ◽  
Structural Elements ◽  
The Relationship

The features of noise generation processes in exhaust and suction noise silencers are shown. A method for testing silencers has been developed. The classification of the main structural elements of exhaust and suction noise silencers, depending on the purpose, is proposed. Experimental studies of the relationship between the acoustic efficiency and the back pressure of silencers from the structural design of the elements are performed. The factors influencing the efficiency in the low-frequency and high-frequency regions of the spectrum are determined: the volume of silencers, the number of chambers, perforation, sound absorption, flow ejection, etc. Recommendations for the design of noise silencers are proposed.

scholarly journals Taxonomy of the Subtribe Maxillariinae (Orchidaceae, Vandoideae) revised

2012 ◽  
Vol 25 (1) ◽  
pp. 13-38 ◽  
Author(s):  
Dariusz L. Szlachetko ◽  
Magdalena Sitko ◽  
Piotr Tukałło ◽  
Joanna Mytnik-Ejsmont
Keyword(s):  
Species Level ◽  
New Combinations ◽  
New Classification

Abstract A new classification of the subtribe Maxillariinae (Orchidaceae) is proposed. Thirty-seven genera are revised. The Camaridium group is divided into seven genera, Adamanthus, Camaridium, Pseudomaxillaria, Psittacoglossum and three described here: Chaseopsis, Chelyella and Viracocha. Ornithidium s.l. is divided into seven genera: Heterotaxis, Laricorchis,Neo-urbania, Nitidobulbon, Ornithidium, Vazquezella and Aucellia, the latter two described here. 193 new combinations on the species level are validated and the relationships among the genera are briefly discussed. A key to the determination of all genera representing Maxillariinae s. s. is provided.

scholarly journals Characterisation of dielectric 3D-printingmaterials at microwave frequencies

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 26
Author(s):  
Andrea Alimenti ◽  
Kostiantyn Torokhtii ◽  
Nicola Pompeo ◽  
Emanuele Piuzzi ◽  
Enrico Silva
Keyword(s):  
Quality Factor ◽  
Loss Tangent ◽  
Complex Permittivity ◽  
High Frequency ◽  
Measurement Method ◽  
Air Gap ◽  
3D Printer ◽  
Reliable Determination ◽  
Microwave Frequencies

<p class="Abstract">3D-printer materials are becoming increasingly appealing, especially for high frequency applications. As such, the electromagnetic characterisation of these materials is an important step in evaluating their applicability for new technological devices. We present a measurement method for complex permittivity evaluation based on a dielectric loaded resonator (DR). Comparing the quality factor <em>Q</em> of the DR with a disk-shaped sample placed on a DR base, with <em>Q</em> obtained when the sample is substituted with an air gap, allows a reliable determination of the loss tangent.</p>

scholarly journals AN EVALUATION ON THE FORMATION AND CLASSIFICATION OF SOME SELJUK CERAMIC TECHNIQUES

2020 ◽  
Vol 9 (76) ◽  
Keyword(s):  
Historical Development ◽  
Islamic Art ◽  
New Classification ◽  
Artistic Value ◽  
Ceramic Art ◽  
Assessment Techniques ◽  
Research Objects ◽  
Historical Developments

In this study, based on the data through related literature and visual data, three different kinds of Ceramic Techniques of Seljuq’s and their historical developments are examined. Determination of “independent invention” which is often repeated in literature regarding “Enameled ware” (overglaze polychrome-painted ware) and “Underglaze-paint” ornamentation techniques studied through a different viewpoint was examined and correctness of aspects that may rise are argued. In this study where “Underglaze-paint” technique, “Enameled wares” and “Seljuk Whitewares” are used as research objects; it aims to enlighten primarily the formation of the product by mentioned techniques and its historical development. For this aim, relevant techniques are put into the general frame of Islamic Art and examined in such a form that provides a holistic perspective. Later on the study, measurement of the artistic value of solid production and criteria in this measurement are problematized. Accordingly, findings gained through new assessment techniques regarding the evaluation of historical productions are applied to Seljuk ceramic techniques -which is the object of the research- and new classification elements and titles are proposed. Keywords: Seljuk ceramic art, enameled ware and underglaze-paint techniques, Seljuk whitewares

An Experimental Validation of a New Method for Multimodel Identification

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Anis Messaoud ◽  
Ridha Ben Abdennour
Keyword(s):  
Nonlinear System ◽  
Experimental Validation ◽  
Chemical Reactor ◽  
New Method ◽  
Data Set ◽  
Weighting Functions ◽  
Systematic Determination

In this paper, we propose a new method for an optimal systematic determination of models' base for multimodel identification. This method is based on the neural classification of data set picked out on a considered nonlinear system. The obtained cluster centers are exploited to provide the weighting functions and to deduce the corresponding dispersions and their models' base. A simulation example and an experimental validation on a chemical reactor are presented to evaluate the effectiveness of the proposed method.

Dynamics of the processes in metal machining

1998 ◽  
Vol 2 ◽  
pp. 115-122
Author(s):  
Donatas Švitra ◽  
Jolanta Janutėnienė
Keyword(s):  
High Frequency ◽  
Machine Tools ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Low Frequency ◽  
Metal Cutting Machine ◽  
Cutting Machine ◽  
Metal Machining

In the practice of processing of metals by cutting it is necessary to overcome the vibration of the cutting tool, the processed detail and units of the machine tool. These vibrations in many cases are an obstacle to increase the productivity and quality of treatment of details on metal-cutting machine tools. Vibration at cutting of metals is a very diverse phenomenon due to both it’s nature and the form of oscillatory motion. The most general classification of vibrations at cutting is a division them into forced vibration and autovibrations. The most difficult to remove and poorly investigated are the autovibrations, i.e. vibrations arising at the absence of external periodic forces. The autovibrations, stipulated by the process of cutting on metalcutting machine are of two types: the low-frequency autovibrations and high-frequency autovibrations. When the low-frequency autovibration there appear, the cutting process ought to be terminated and the cause of the vibrations eliminated. Otherwise, there is a danger of a break of both machine and tool. In the case of high-frequency vibration the machine operates apparently quiently, but the processed surface feature small-sized roughness. The frequency of autovibrations can reach 5000 Hz and more.

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