scholarly journals Mathematical Model of a Three-Phase Induction Machine in a Natural abc Reference Frame Utilizing the Method of Numerical Integration of Average Voltages at the Integration Step and Its Application to the Analysis of Electromechanical Systems

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Oleksiy Kuznyetsov
Keyword(s):  
Reference Frame ◽  
High Speed ◽  
Numerical Models ◽  
Second Order ◽  
Integration Step ◽  
Electromechanical Systems ◽  
Suitable Alternative ◽  
First Order ◽  
Operation Speed ◽  
Three Phase

Recent advances in the real-time simulation of electric machines are linked with the increase in the operation speed of the numerical models retaining the calculation accuracy. We propose utilizing the method of average voltages at the integration step (AVIS) for the design of a three-phase induction machine’s model in its natural abc reference frame. The method allows for avoiding rotational e.m.f. calculation at every step; in turn, the electromagnetic energy conversion is accounted by the change of flux-linkage. The model is integrated into the object-oriented environment in C++ for designing the computer models of electromechanical systems. The design of the model of an electromechanical system utilizing the proposed approach is explained in an example. The behavior of the numerical models of a three-phase IM has been compared for the set of conventional numerical methods as well as first- and second-order AVIS. It has been demonstrated that both first- and second-order AVIS methods are suitable tools for high-speed applications, namely, AVIS provides higher maximum possible integration step (e.g., first-order AVIS provides 4 times higher than the second-order Runge–Kutta method, and the second-order AVIS provides 2.5 times higher than the first-order method). Therefore, we consider the most preferable order of the AVIS method for the high-speed applications is the second order, while the first order may be a suitable alternative to increase the calculation speed by 30% with the acceptable decrease in the accuracy.

scholarly journals Heterogeneity and Convergence of Olfactory First-Order Neurons Account for the High Speed and Sensitivity of Second-Order Neurons

2014 ◽  
Vol 10 (12) ◽  
pp. e1003975 ◽  
Author(s):  
Jean-Pierre Rospars ◽  
Alexandre Grémiaux ◽  
David Jarriault ◽  
Antoine Chaffiol ◽  
Christelle Monsempes ◽  
...  
Keyword(s):  
High Speed ◽  
Second Order ◽  
First Order

scholarly journals Electromagnetic reducers in electromechanical systems

2021 ◽  
pp. 42-46
Author(s):  
Igor Tkachuk ◽  
Mykhailo Kovalenko
Keyword(s):  
Wind Turbines ◽  
High Speed ◽  
Numerical Models ◽  
Mechanical Energy ◽  
Experimental Studies ◽  
Total Weight ◽  
Electromechanical Systems ◽  
Low Speed ◽  
Electric Generator ◽  
Additional Noise

      Currently, due to the rising cost of electricity, low-power wind turbines (1-5 kW) are often used to supply consumers with electricity. In this case, wind turbines are used with both horizontal and vertical axes of rotation, the speed of which at an average wind speed V = 5 ÷ 10 m / s and is quite low, and is approximately n = 100 - 300 rpm. A low-speed electric generator for a wind generator with such a speed of rotation with a direct connection of the wind rotor shaft and the electric generator has a large number of poles and reaches a fairly large size. Therefore, magnifying gears (multiplexers) are often used and can increase the speed of the electric generator several times and, thus, reduce the mass of its active part, because the electromagnetic moment is proportional to the volume of the electric machine. However, manual transmissions are a source of additional noise, require frequent maintenance and reduce the durability of the wind turbine. This article will use permanent magnet reducers for wind turbines, which, unlike mechanical reducers, do not create additional noise, do not require lubrication, their durability is higher, operating costs are also significantly reduced, while the magnetic reducer can be integrated with an electric generator. at a wind rotor power P = 4 kW and speed n = 100-300 rpm, high-speed electric generator and magnetic reducer have approximately 2 times less total weight of magnets and 1.7 times less total weight of active materials (magnetic reducer + electric generator) than a low-speed multipole external generator. The aim of the study is to develop and implement an electromagnetic reducer in electromechanical systems. The basis of such systems are high-coercive magnets. To achieve this goal, the following tasks are set: - literary-patent search on the research topic; - selection of a prototype of a magnetic reducer and calculation of its main parameters; - development of graphical and numerical models to evaluate the effectiveness of the developed prototype; - optimization of the design of the magnetic reducer; - development of a system for converting mechanical energy with low potential into electricity; - prototyping and experimental studies of the system of conversion of mechanical energy with low potential into electrical energy

scholarly journals Adsorption of Estrogenic Hormones in Aqueous Solution Using Electrospun Nanofibers From Waste Cigarette Butts: Kinetics, Mechanism, and Reusability

2021 ◽  
Author(s):  
Muhammad Yasir ◽  
Tomáš Šopík ◽  
Rahul Patwa ◽  
Dušan Kimmer ◽  
Vladimír Sedlařík
Keyword(s):  
Fractional Power ◽  
Small Diameter ◽  
Electrospun Nanofibers ◽  
Second Order ◽  
Order Kinetic ◽  
Suitable Alternative ◽  
First Order ◽  
Estrogenic Hormones ◽  
Pseudo Second Order ◽  
Pseudo First Order

Abstract This study emphasizes rapid and simultaneous adsorptive removal of estrogenic hormones (EHs): estrone (E1), 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and estriol (E3) from wastewater using recycled waste cigarette electrospun nanofibers (WCENFs). The nanofibers exhibited a small diameter (196±65 nm) and large surface area (18.05 m 2 /g), along with a strong affinity towards all EHs by adsorption due to abundant hydrogen bonding interactions. A one-step high-performance liquid chromatography technique was developed to detect each EH present in the solution simultaneously. The adsorption kinetics helps select optimum conditions for the large-scale removal process, so experimental data using pseudo-first-order, pseudo-second-order, intra-particle diffusion, Elovich, and fractional power models were fitted. It was found that E1, E2, and EE2 followed pseudo-second-order kinetics while E3 followed pseudo-first-order kinetic models. The total adsorption capacity on WCENFs was determined to be 2.14 mg/g, whereas the individual adsorption capacities of E1, E2, EE2, and E3 were found to be 0.551, 0.532, 0.687, and 0.369 mg/g, respectively. The percentage efficiency of WCENFs was highest with EE2 ~64.3% and least with E3 ~34.6%. Adsorption-desorption studies revealed that WCENFs could repeatedly be used four times. The reported results indicate a significant potential of WCENFs to be an effective sorbent and portable filter for simultaneous estrogenic hormone removal. WCENFs filter is a suitable alternative to commercial Cellulose acetate filters.

Kinematics in a Diffracted Wave Field: Particle Image Velocimetry (PIV) and Numerical Models

2005 ◽  
Author(s):  
Trygve Kristiansen ◽  
Rolf Baarholm ◽  
Geir J. Ro̸rtveit ◽  
Ernst W. Hansen ◽  
Carl Trygve Stansberg
Keyword(s):  
Potential Theory ◽  
High Speed ◽  
Numerical Models ◽  
Vertical Cylinder ◽  
Industrial Applications ◽  
Second Order ◽  
Surface Elevation ◽  
High Speed Camera ◽  
Non Linear ◽  
Theoretical Results

As the use of CFD in industrial applications increases, so does the need for verification and validation of the theoretical/numerical results. This paper focuses on tools for validation and in particular, on the use of Particle Imaging Velocimetry (PIV) as such a tool. Diffraction of regular waves due to a single, fixed vertical cylinder is investigated. Theoretical results of wave run-up and wave kinematics are compared to measurements from model tests. Theoretical results are obtained by second order potential theory and by fully non-linear CFD computations. The second order potential theory frequency-domain results are computed by the industry standard code WAMIT, while the fully nonlinear time-domain simulations are performed by the commercial CFD code Flow-3D. Measurements are obtained by means of wave probes, PIV and snapshots taken with a high-speed camera. The experiments are made with the model in place as well as without the model, for validation of the incident flow field. For the identification of non-linear effects, the steepness of the waves is varied. The surface elevation is measured by means of the wave probes, while the PIV equipment measures the kinematics. High quality photos taken by the high-speed camera give a detailed overview of the surface elevation for inspection. In addition to focusing on validation tools, the paper also addresses some critical aspects associated with the CFD computations, such as the modeling of boundary conditions. The work is based partly upon results from the WaveLand JIP, Phase 2.

A High-Order Solution for the Added Stability Lobes in Intermittent Machining

2000 ◽  
Author(s):  
William T. Corpus ◽  
William J. Endres
Keyword(s):  
Closed Form ◽  
High Speed ◽  
Higher Order ◽  
Second Order ◽  
Machining Processes ◽  
Analytical Technique ◽  
First Order ◽  
Order Solution ◽  
Order Case ◽  
Speed Stability

Abstract An earlier work by the authors presented a solution for the added ultrahigh-speed stability lobe that has been shown to exist for intermittent and other periodically time varying machining processes. That earlier first-order solution was not clearly extendible to a higher order. A more general analytical technique presented here does permit higher-order results. The solution is developed first for the case of zero damping for which a final closed-form symbolic result can be realized up to second order. More important than improved accuracy, the higher-order nature of the result confirms that there exist multiple added lobes and permits a mathematical description of their locations along the spindle-speed axis. A solution is then derived for the structurally damped case, where the first-order case permits a final closed-form symbolic result while the second-order case requires computational evaluation. The first-order result matches perfectly the previously published one, as expected. The second-order result improves accuracy, measured relative to numerical simulation results, and, more important, permits a second added lobe to be predicted. The second added lobe tends to cut into the region of the high-speed stability peak that is predicted under traditional zero-frequency (time-averaged) analyses. The damped solutions also indicate that structural damping of the dominant mode becomes virtually unimportant at ultrahigh speeds.

Second order vibration of flexible shafts

1965 ◽  
Vol 259 (1095) ◽  
pp. 1-31 ◽  
Keyword(s):  
Forced Vibration ◽  
High Speed ◽  
Flexural Rigidity ◽  
Second Order ◽  
Design Stage ◽  
Theoretical Treatment ◽  
Specific Nature ◽  
Bending Vibration ◽  
Considerable Difficulty ◽  
First Order

First order (i.e. ' once per revolution’) forced bending vibration of high speed flexible shafts is caused by the small defects of initial bend and lack of mass balance that are inevitably present in any rotor. It can be reduced to an acceptable level by modal balancing. Large modern alternator rotors are particularly sensitive to vibration and it has been found that, while accurate balancing is of cardinal importance, it is not sufficient to remove all vibration. There remains, in particular, second order (or ‘twice per revolution’) forced vibration which arises from the dual flexural rigidity that is virtually inescapable in a two-pole machine; the motion is excited by the weight of the rotor. This has now emerged as the source of considerable difficulty, largely because it can be cured only at the design stage and cannot be ‘ balanced ’. (Certain 'trimming’ modifications can be made, of course, but these present formidable problems of their own.) A theoretical treatment of the problem is given which is much less restrictive than that previously available. An analytical basis is provided for further work of a more specific nature, should it be required. The motion is examined mode by mode and various properties of second order vibration are exposed. In particular it is shown that the polar representation that has been successfully used in the analysis of first order vibration is also of value with second order vibration. This is illustrated and confirmed with results taken from a 350 MW rotor.

Nonlinear Analysis of Visual Evoked Potentials Elicited by Color Stimulation

1997 ◽  
Vol 36 (04/05) ◽  
pp. 315-318 ◽  
Author(s):  
K. Momose ◽  
K. Komiya ◽  
A. Uchiyama
Keyword(s):  
Visual System ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Normal Subjects ◽  
Second Order ◽  
First Order ◽  
The Relationship ◽  
Perceived Color ◽  
Second Order Nonlinearity ◽  
Visual Evoked

Abstract:The relationship between chromatically modulated stimuli and visual evoked potentials (VEPs) was considered. VEPs of normal subjects elicited by chromatically modulated stimuli were measured under several color adaptations, and their binary kernels were estimated. Up to the second-order, binary kernels obtained from VEPs were so characteristic that the VEP-chromatic modulation system showed second-order nonlinearity. First-order binary kernels depended on the color of the stimulus and adaptation, whereas second-order kernels showed almost no difference. This result indicates that the waveforms of first-order binary kernels reflect perceived color (hue). This supports the suggestion that kernels of VEPs include color responses, and could be used as a probe with which to examine the color visual system.

Imaginings

2017 ◽  
Vol 9 (3) ◽  
pp. 17-30
Author(s):  
Kelly James Clark
Keyword(s):  
Religious Tradition ◽  
Second Order ◽  
Fine Tuning ◽  
Intellectual Humility ◽  
First Order ◽  
Natural Processes ◽  
Empirically Supported ◽  
Group Violence ◽  
The World ◽  
The Universe

In Branden Thornhill-Miller and Peter Millican’s challenging and provocative essay, we hear a considerably longer, more scholarly and less melodic rendition of John Lennon’s catchy tune—without religion, or at least without first-order supernaturalisms (the kinds of religion we find in the world), there’d be significantly less intra-group violence. First-order supernaturalist beliefs, as defined by Thornhill-Miller and Peter Millican (hereafter M&M), are “beliefs that claim unique authority for some particular religious tradition in preference to all others” (3). According to M&M, first-order supernaturalist beliefs are exclusivist, dogmatic, empirically unsupported, and irrational. Moreover, again according to M&M, we have perfectly natural explanations of the causes that underlie such beliefs (they seem to conceive of such natural explanations as debunking explanations). They then make a case for second-order supernaturalism, “which maintains that the universe in general, and the religious sensitivities of humanity in particular, have been formed by supernatural powers working through natural processes” (3). Second-order supernaturalism is a kind of theism, more closely akin to deism than, say, Christianity or Buddhism. It is, as such, universal (according to contemporary psychology of religion), empirically supported (according to philosophy in the form of the Fine-Tuning Argument), and beneficial (and so justified pragmatically). With respect to its pragmatic value, second-order supernaturalism, according to M&M, gets the good(s) of religion (cooperation, trust, etc) without its bad(s) (conflict and violence). Second-order supernaturalism is thus rational (and possibly true) and inconducive to violence. In this paper, I will examine just one small but important part of M&M’s argument: the claim that (first-order) religion is a primary motivator of violence and that its elimination would eliminate or curtail a great deal of violence in the world. Imagine, they say, no religion, too.Janusz Salamon offers a friendly extension or clarification of M&M’s second-order theism, one that I think, with emendations, has promise. He argues that the core of first-order religions, the belief that Ultimate Reality is the Ultimate Good (agatheism), is rational (agreeing that their particular claims are not) and, if widely conceded and endorsed by adherents of first-order religions, would reduce conflict in the world.While I favor the virtue of intellectual humility endorsed in both papers, I will argue contra M&M that (a) belief in first-order religion is not a primary motivator of conflict and violence (and so eliminating first-order religion won’t reduce violence). Second, partly contra Salamon, who I think is half right (but not half wrong), I will argue that (b) the religious resources for compassion can and should come from within both the particular (often exclusivist) and the universal (agatheistic) aspects of religious beliefs. Finally, I will argue that (c) both are guilty, as I am, of the philosopher’s obsession with belief. 

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