Добірка наукової літератури з теми "Non-sinusoidal regimes"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Non-sinusoidal regimes".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Статті в журналах з теми "Non-sinusoidal regimes"
1
Saiki, H., G. Ngaile, and L. Ruan. "Characterization of Adhesive Strength of Phosphate Coatings in Cold Metal Forming." Journal of Tribology 119, no. 4 (October 1, 1997): 667–71. http://dx.doi.org/10.1115/1.2833867.
Повний текст джерелаАнотація:
A test method is proposed to characterize adhesive strength of phosphate coatings based on the various deformation patterns at the tool-workpiece interface. The deformation patterns were induced by tools of different surface geometrical profiles, i.e., flat surface, sinusoidal surface, saw-tooth surface and multi-surface profiles, in a localized rod drawing technique. With change in the tool geometry, three deformation regimes were observed, i.e., full film lubrication regime, mixed regime, and seizure regimes, which were categorized by the level of friction coefficient attained, and the degree of galling observed on the surface of the drawn specimens. The full film lubrication regimes were noticed when flat dies were used. In this case, the friction coefficient was maintained at nearly μ = 0.065, irrespective of the change in the surface roughness of the tools and reduction. With sinusoidal surface and other non-flat dies, mixed regime and seizure regimes were observed, and the friction coefficient varied from μ = 0.1 to 0.3. To complement the friction data, surface analysis of the tool-workpiece interface was also conducted. The frictional range of μ = 0.065 to 0.3 obtained in this study, therefore, provides for a manageable characterization of phosphate coatings for cold metal forming of objects with intricate shapes.
2
Ionita, Valentin, Lucian Petrescu, and Emil Cazacu. "Improved estimation of iron losses for non-sinusoidal voltages." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 37, no. 5 (September 3, 2018): 1698–706. http://dx.doi.org/10.1108/compel-12-2017-0527.
Повний текст джерелаАнотація:
Purpose The electrical machines connected to modern electric power grids are non-sinusoidal excited, and their augmented losses, including iron losses, limit their working characteristics. This paper aims to propose a prediction method for iron losses in non-oriented grains (NO) FeSi sheets under non-sinusoidal voltage, involving an inverse classical Preisach hysteresis model and the time-integration of each loss component. Design/methodology/approach The magnetic history management in inverse Preisach model is optimized and a numerical Everett function is identified from measured symmetrical hysteresis cycles. The experimental data for sinusoidal waveforms obtained by a single sheet tester were also used to identify the parameters involved in Bertotti’ losses separation method. The non-sinusoidal magnetic induction waveform, corresponding to a measured voltage in an industrial electrical grid, was the input for Preisach model, the output magnetic field being accurately computed. The hysteresis, classical and excess losses are calculated by time-integration and the total losses are compared with those obtained for sinusoidal excitation. Findings The proposed method allows to estimate the iron losses for non-sinusoidal magnetic induction, using carefully identified parameters of FeSi NO sheets, using experimental data from sinusoidal regimes. Originality/value The method accuracy is assured by using a numerical Everett function, a variable Preisach grid step (adapted for the high non-linearity of FeSi sheets) and high-order fitting polynomials for the microscopic parameters involved in the excess loss estimation. The procedure allows a better design of magnetic cores and an improved estimation of the electric machine derating for non-sinusoidal voltages.
3
Krishnakumaran, R., Mohammed Raees, and Supratim Ray. "Shape analysis of gamma rhythm supports a superlinear inhibitory regime in an inhibition-stabilized network." PLOS Computational Biology 18, no. 2 (February 14, 2022): e1009886. http://dx.doi.org/10.1371/journal.pcbi.1009886.
Повний текст джерелаАнотація:
Visual inspection of stimulus-induced gamma oscillations (30–70 Hz) often reveals a non-sinusoidal shape. Such distortions are a hallmark of non-linear systems and are also observed in mean-field models of gamma oscillations. A thorough characterization of the shape of the gamma cycle can therefore provide additional constraints on the operating regime of such models. However, the gamma waveform has not been quantitatively characterized, partially because the first harmonic of gamma, which arises because of the non-sinusoidal nature of the signal, is typically weak and gets masked due to a broadband increase in power related to spiking. To address this, we recorded local field potential (LFP) from the primary visual cortex (V1) of two awake female macaques while presenting full-field gratings or iso-luminant chromatic hues that produced huge gamma oscillations with prominent peaks at harmonic frequencies in the power spectra. We found that gamma and its first harmonic always maintained a specific phase relationship, resulting in a distinctive shape with a sharp trough and a shallow peak. Interestingly, a Wilson-Cowan (WC) model operating in an inhibition stabilized mode could replicate this shape, but only when the inhibitory population operated in the super-linear regime, as predicted recently. However, another recently developed model of gamma that operates in a linear regime driven by stochastic noise failed to produce salient harmonics or the observed shape. Our results impose additional constraints on models that generate gamma oscillations and their operating regimes.
4
Gsell, Simon, Rémi Bourguet, and Marianna Braza. "Vortex-induced vibrations of a cylinder in planar shear flow." Journal of Fluid Mechanics 825 (July 20, 2017): 353–84. http://dx.doi.org/10.1017/jfm.2017.386.
Повний текст джерелаАнотація:
The system composed of a circular cylinder, either fixed or elastically mounted, and immersed in a current linearly sheared in the cross-flow direction, is investigated via numerical simulations. The impact of the shear and associated symmetry breaking are explored over wide ranges of values of the shear parameter (non-dimensional inflow velocity gradient, $\unicode[STIX]{x1D6FD}\in [0,0.4]$) and reduced velocity (inverse of the non-dimensional natural frequency of the oscillator, $U^{\ast }\in [2,14]$), at Reynolds number $Re=100$; $\unicode[STIX]{x1D6FD}$, $U^{\ast }$ and $Re$ are based on the inflow velocity at the centre of the body and on its diameter. In the absence of large-amplitude vibrations and in the fixed body case, three successive regimes are identified. Two unsteady flow regimes develop for $\unicode[STIX]{x1D6FD}\in [0,0.2]$ (regime L) and $\unicode[STIX]{x1D6FD}\in [0.2,0.3]$ (regime H). They differ by the relative influence of the shear, which is found to be limited in regime L. In contrast, the shear leads to a major reconfiguration of the wake (e.g. asymmetric pattern, lower vortex shedding frequency, synchronized oscillation of the saddle point) and a substantial alteration of the fluid forcing in regime H. A steady flow regime (S), characterized by a triangular wake pattern, is uncovered for $\unicode[STIX]{x1D6FD}>0.3$. Free vibrations of large amplitudes arise in a region of the parameter space that encompasses the entire range of $\unicode[STIX]{x1D6FD}$ and a range of $U^{\ast }$ that widens as $\unicode[STIX]{x1D6FD}$ increases; therefore vibrations appear beyond the limit of steady flow in the fixed body case ($\unicode[STIX]{x1D6FD}=0.3$). Three distinct regimes of the flow–structure system are encountered in this region. In all regimes, body motion and flow unsteadiness are synchronized (lock-in condition). For $\unicode[STIX]{x1D6FD}\in [0,0.2]$, in regime VL, the system behaviour remains close to that observed in uniform current. The main impact of the shear concerns the amplification of the in-line response and the transition from figure-eight to ellipsoidal orbits. For $\unicode[STIX]{x1D6FD}\in [0.2,0.4]$, the system exhibits two well-defined regimes: VH1 and VH2 in the lower and higher ranges of $U^{\ast }$, respectively. Even if the wake patterns, close to the asymmetric pattern observed in regime H, are comparable in both regimes, the properties of the vibrations and fluid forces clearly depart. The responses differ by their spectral contents, i.e. sinusoidal versus multi-harmonic, and their amplitudes are much larger in regime VH1, where the in-line responses reach $2$ diameters ($0.03$ diameters in uniform flow) and the cross-flow responses $1.3$ diameters. Aperiodic, intermittent oscillations are found to occur in the transition region between regimes VH1 and VH2; it appears that wake–body synchronization persists in this case.
5
Hu, Qiang-Qiang, and Yong-Liang Yu. "The hydrodynamic effects of undulating patterns on propulsion and braking performances of long-based fin." AIP Advances 12, no. 3 (March 1, 2022): 035319. http://dx.doi.org/10.1063/5.0083912.
Повний текст джерелаАнотація:
Bio-inspired long-based undulating fin propulsion is commonly employed in biological autonomous underwater vehicles (BAUVs), while the hydrodynamic characteristics of various undulating patterns are different. To investigate what kind of undulating pattern has outstanding propulsion or braking performance for BAUVs in directional maneuvers, undulations with four basic undulating patterns are numerically examined under the Open-source Field Operation And Manipulation environment at the Reynolds number of 5 × 102, 5 × 103, and 5 × 104, corresponding to viscous, transitional, and inertial flow regimes, respectively. The study is conducted at various non-dimensional phase speeds c (0.5–2.0, normalized by incoming flow speed) at a constant maximum amplitude of 0.08 and a wavelength of 0.5 (both are normalized by the fin cord length) to imitate the long-based fin. The numerical results indicate that the undulating fin motion with the amplitude envelope gradually increasing from the anterior part to the posterior (conical sinusoidal wave) part may be preferable for thrust generation; undulating with the amplitude envelope increasing from the anterior part to the mid part and decreasing toward the posterior (fusiform sinusoidal wave) presents the superior braking performance when the phase speed is low enough. Moreover, the influence of undulating patterns on the wake structure is analyzed. Through further comparative analysis for propulsion and braking performances, the results obtained here may have instructional significance to the propulsion mechanism in bionic design.
6
Tutty, O. R., and T. J. Pedley. "Oscillatory flow in a stepped channel." Journal of Fluid Mechanics 247 (February 1993): 179–204. http://dx.doi.org/10.1017/s0022112093000436.
Повний текст джерелаАнотація:
Two-dimensional, unsteady flow of a viscous, incompressible fluid in a stepped channel has been studied by the numerical solution of the Navier–Stokes equation using an accurate finite-difference method.With a sinusoidal mass flow rate, the problem has three governing parameters: the Reynolds number, the Strouhal number, and the step height. The effects on the flow of varying all three parameters has been investigated systematically. In appropriate parameter regimes, a strong ‘vortex wave’ is generated during the forward phase when the flow is over the step into the expansion. Secondary effects on the wave can result in a complex flow pattern with each major structure of the flow consisting of an eddy with more than one core. No such wave is found during the reverse phase of the flow. The generation and development of the wave is examined in some detail, and our results are compared and contrasted with those of previous studies, both experimental and theoretical, of flow in non-uniform vessels.
7
Cheng, W., D. I. Pullin, and R. Samtaney. "Large-eddy simulation of flow over a grooved cylinder up to transcritical Reynolds numbers." Journal of Fluid Mechanics 835 (November 27, 2017): 327–62. http://dx.doi.org/10.1017/jfm.2017.767.
Повний текст джерелаАнотація:
We report wall-resolved large-eddy simulation (LES) of flow over a grooved cylinder up to the transcritical regime. The stretched-vortex subgrid-scale model is embedded in a general fourth-order finite-difference code discretization on a curvilinear mesh. In the present study $32$ grooves are equally distributed around the circumference of the cylinder, each of sinusoidal shape with height $\unicode[STIX]{x1D716}$, invariant in the spanwise direction. Based on the two parameters, $\unicode[STIX]{x1D716}/D$ and the Reynolds number $Re_{D}=U_{\infty }D/\unicode[STIX]{x1D708}$ where $U_{\infty }$ is the free-stream velocity, $D$ the diameter of the cylinder and $\unicode[STIX]{x1D708}$ the kinematic viscosity, two main sets of simulations are described. The first set varies $\unicode[STIX]{x1D716}/D$ from $0$ to $1/32$ while fixing $Re_{D}=3.9\times 10^{3}$. We study the flow deviation from the smooth-cylinder case, with emphasis on several important statistics such as the length of the mean-flow recirculation bubble $L_{B}$, the pressure coefficient $C_{p}$, the skin-friction coefficient $C_{f\unicode[STIX]{x1D703}}$ and the non-dimensional pressure gradient parameter $\unicode[STIX]{x1D6FD}$. It is found that, with increasing $\unicode[STIX]{x1D716}/D$ at fixed $Re_{D}$, some properties of the mean flow behave somewhat similarly to changes in the smooth-cylinder flow when $Re_{D}$ is increased. This includes shrinking $L_{B}$ and nearly constant minimum pressure coefficient. In contrast, while the non-dimensional pressure gradient parameter $\unicode[STIX]{x1D6FD}$ remains nearly constant for the front part of the smooth cylinder flow, $\unicode[STIX]{x1D6FD}$ shows an oscillatory variation for the grooved-cylinder case. The second main set of LES varies $Re_{D}$ from $3.9\times 10^{3}$ to $6\times 10^{4}$ with fixed $\unicode[STIX]{x1D716}/D=1/32$. It is found that this $Re_{D}$ range spans the subcritical and supercritical regimes and reaches the beginning of the transcritical flow regime. Mean-flow properties are diagnosed and compared with available experimental data including $C_{p}$ and the drag coefficient $C_{D}$. The timewise variation of the lift and drag coefficients are also studied to elucidate the transition among three regimes. Instantaneous images of the surface, skin-friction vector field and also of the three-dimensional Q-criterion field are utilized to further understand the dynamics of the near-surface flow structures and vortex shedding. Comparison of the grooved-cylinder flow with the equivalent flow over a smooth-wall cylinder shows structural similarities but significant differences. Both flows exhibit a clear common signature, which is the formation of mean-flow secondary separation bubbles that transform to other local flow features upstream of the main separation region (prior separation bubbles) as $Re_{D}$ is increased through the respective drag crises. Based on these similarities it is hypothesized that the drag crises known to occur for flow past a cylinder with different surface topographies is the result of a change in the global flow state generated by an interaction of primary flow separation with secondary flow recirculating motions that manifest as a mean-flow secondary bubble. For the smooth-wall flow this is accompanied by local boundary-layer flow transition to turbulence and a strong drag crisis, while for the grooved-cylinder case the flow remains laminar but unsteady through its drag crisis and into the early transcritical flow range.
8
Ahmed, Gulraiz, Mathieu Sellier, Yeaw Chu Lee, Mark Jermy, and Michael Taylor. "Rheological effects on the levelling dynamics of thin fluid films." International Journal of Numerical Methods for Heat & Fluid Flow 25, no. 8 (November 2, 2015): 1850–67. http://dx.doi.org/10.1108/hff-10-2013-0295.
Повний текст джерелаАнотація:
Purpose – The purpose of this paper is to investigate numerically the effect of rheology on the leveling of thin fluid films on horizontal solid substrates. Design/methodology/approach – A mathematical model based on the lubrication approximation which defines non-Newtonian rheology using a Power-law model is presented. The rheology is described by two parameters: the consistency factor and the flow behavior index. The resulting highly non-linear coupled set of equations is discretized using Finite-Difference and the resulting algebraic system is solved via an efficient Multigrid algorithm. Findings – Importantly, the non-dimensionalization process leads to a pair of Partial Differential Equations which depends on one parameter only, the flow behavior index. The authors show that the consistency factor only affects the time scale of the leveling process, hence stretching or contracting the time line. Results for the leveling of sinusoidal perturbations of the fluid film highlights important differences between the leveling of shear-thinning and shear-thickening fluids. In a normalized time frame, the onset of leveling occurs earlier for the shear-thinning fluid than for the shear-thickening one. However, the dimensionless leveling rate is higher for the shear-thickening fluid than the shear-thinning one. This results in a “threshold thickness” which delimits two regimes: the shear-thinning fluid levels to a thickness above this threshold faster than the shear-thickening fluid but the opposite is true for a film thickness below this threshold. An important aspect of this study is the verification of the numerical implementation using the Method of Manufactured Solutions (MMS), a first in the context of thin film studies. The paper also highlights differences between the leveling of two-dimensional and three-dimensional thickness perturbations. Originality/value – The study of the leveling of disturbances at the free surface of a liquid film using a Power-law rheological model does not appear to have been covered in the literature. Also, the paper uses the MMS to test the validity of the implementation. This appears to be the first time it has been used in the context of the lubrication approximation. Finally, unlike most prior studies, the work does away with the planar assumption.
9
DAREKAR, RUPAD M., and SPENCER J. SHERWIN. "Flow past a square-section cylinder with a wavy stagnation face." Journal of Fluid Mechanics 426 (January 10, 2001): 263–95. http://dx.doi.org/10.1017/s0022112000002299.
Повний текст джерелаАнотація:
Numerical investigations have been performed for the flow past square-section cylinders with a spanwise geometric deformation leading to a stagnation face with a sinusoidal waviness. The computations were performed using a spectral/hp element solver over a range of Reynolds numbers from 10 to 150.Starting from fully developed shedding past a straight cylinder at a Reynolds number of 100, a sufficiently high waviness is impulsively introduced resulting in the stabilization of the near wake to a time-independent state. It is shown that the spanwise waviness sets up a cross-flow within the growing boundary layer on the leading-edge surface thereby generating streamwise and vertical components of vorticity. These additional components of vorticity appear in regions close to the inflection points of the wavy stagnation face where the spanwise vorticity is weakened. This redistribution of vorticity leads to the breakdown of the unsteady and staggered Kármán vortex wake into a steady and symmetric near-wake structure. The steady nature of the near wake is associated with a reduction in total drag of about 16% at a Reynolds number of 100 compared with the straight, non-wavy cylinder.Further increases in the amplitude of the waviness lead to the emergence of hairpin vortices from the near-wake region. This wake topology has similarities to the wake of a sphere at low Reynolds numbers. The physical structure of the wake due to the variation of the amplitude of the waviness is identified with five distinct regimes. Furthermore, the introduction of a waviness at a wavelength close to the mode A wavelength and the primary wavelength of the straight square-section cylinder leads to the suppression of the Kármán street at a minimal waviness amplitude.
10
Rob, R., C. Panoiu, and M. Panoiu. "Study regarding the non-sinusoidal regime imposed by nonlinear loads." IOP Conference Series: Materials Science and Engineering 106 (February 1, 2016): 012023. http://dx.doi.org/10.1088/1757-899x/106/1/012023.
Повний текст джерелаДисертації з теми "Non-sinusoidal regimes"
1
Haugan, Thomas Sagvold. "Smart Grid: Shunt Compensation in Non-Sinusoidal Regimes." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20732.
Повний текст джерелаАнотація:
The electric power theory is of fundamental importance in most aspects of electric power engineering, enabling to analyze and control the grid based on an unambiguous physical interpretation of the power and current flow. The futuristic SmartGrid concept will include scenarios of potentially very challenging network conditions, due to large impact of non-linear loads, combined with unsymmetric and non-sinusoidal voltage regimes. New and more advanced power theories are needed, in order to maintain correct physical understanding of the power grid, independently of voltage conditions. Moreover sophisticated power theories can help identify and eliminate detrimental effects induced by loads; i.e. unsymmetry, reactive power consumption and harmonic pollution. This project has reviewed the recent and promising conservative power theory (CPT). Major part of the project was dedicated to experimental research, evaluating the CPT purely from a power theory perspective. Central part of these experiments was a real-time rapid prototyping system (RPS) and three-phase voltage source converter. Control system for the programmable voltage source, data acquisition and CPT-algorithm were implemented by the RPS. Based on extensive tests it was found that the CPT offers enhanced and physical correct interpretation of current and power flow. Obtained results from the virtual instrumentation are principally consistent with and support previous research presented in the literature. Second part evaluated the CPT in context of shunt active power filter (SAPF). Experimental implementation of SAPF failed, mainly as the RPS did not provide sufficient sampling rate. Selected cases of reactive and harmonic compensation were demonstrated, utilizing computer modeling tools (MATLAB/Simulink). The results conclude that the CPT performs excellent selective compensation, only when grid voltages are balanced sinusoidal. In scenarios of unsymmetric or distorted voltages, the compensation strategies provided by the CPT are apparently less versatile and effective, compared to the popular pq-theory. Overall this study demonstrated that optimal network operation can only be achieved, through the joint action of series and parallel compensators. Future work will amongst others include further in-depth study of the rapid prototyping system, and experimental implementation of SAPF.
2
Иерусалимова, Татьяна Сергеевна. "Влияние несинусоидальных режимов роботы электрических сетей на процессы электропотребления". Thesis, НТУ "ХПИ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/22731.
Повний текст джерелаАнотація:
Диссертация на соискание ученой степени кандидата технических наук по специальности 05.14.02 – электрические станции, сети и системы. – Национальный технический университет – "Харьковский политехнический институт", Харьков 2016.
Диссертация посвящена решению важной научно-технической задачи влияния несинусоидальных режимов работы электрических сетей на процессы электропотребления в точке подключения неидеальной (несимметричной и нелинейной) нагрузки к сети с несимметричным и несинусоидальным напряжением. На основе теоретических исследований, использующих единый векторный подход, получена векторная математическая модель несинусоидальных и несимметричных энергетических режимов в четырехпроводной системе. Векторный подход использует два дополняющих друг друга метода: временной и спектральный метод. Временной подход использует понятия классической скалярной и новой векторной мгновенной мощности. Подход позволяет корректно классифицировать текущие установившиеся энергетические режимы в точке подключения неидеальной (несимметричной и нелинейной) нагрузки к четырехпроводной сети. Спектральный подход применяет комплексный ряд Фурье к трехфазным процессам тока и напряжения. Подход использует классические понятия скалярных интегральных мощностей (активная мощность и реактивная мощность) и позволяет получить новые интегральные векторные мощности (мощности небаланса, пульсаций). Спектральный подход применен для установления связей между мгновенными и интегральными мощностями и позволяет качественно и количественно анализировать несбалансированный и неуравновешенный режимы электроснабжения. Предложено ортогональное разложение полного несинусоидального тока на четыре составляющие: общую компоненту высших гармоник и 3 компоненты основной частоты – активный, реактивный и несбалансированный токи. Для уточенной модели показана эквивалентность ортогонального разложения полного тока, квадратичного разложения потерь и уравнения интегральных мощностей. Методом визуального программирования Simulink реализована имитационная модель несинусоидального энергетического режима в пакете Matlab. Проведенное моделирование подтвердило правильность теоретических исследований.Thesis for scientific degree of candidate of technical sciences, specialty 05.14.02 – Еlectrical power stations, networks and systems. – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2016. The thesis is dedicated to solution of the important scientific and technical problem of influence of the non-sinusoidal regimes of electric networks operation on the processes of power consumption at the point of connection of a non-ideal (asymmetrical and nonlinear) load to the network with asymmetrical and non-sinusoidal voltage. Based on theoretical studies using a common vector approach, a vector mathematical model of non-sinusoidal and asymmetrical power regimes in a four-phase system has been obtained. The vector approach uses two complementary methods: time and spectral. Time approach uses concepts of the classical scalar and a new vector instant power. The spectral approach uses complex Fourier series for three-phase current and voltage processes. The approach uses the classical notions of scalar integral powers (active power and reactive power) and provides obtaining new integrated vector powers (power of unbalance, power of pulsations). It was shown on an example of activereactive nonsymmetrical linear load how the proposed mathematical model allows refining and detailing the decomposition of full power of the IEEE Standard 1459 non-sinusoidal mode. Imitating model of non-sinusoidal power regime was implemented with the help of visual programming method Simulink in the software package Matlab. Carried simulations have confirmed the correctness of theoretical research.
3
Ієрусалімова, Тетяна Сергіївна. "Вплив несинусоїдальних режимів роботи електричних мереж на процеси електроспоживання". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/22730.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.14.02 – електричні станції, мережі і системи. – Національний технічний університет – "Харківський політехнічний інститут", Харків 2016.
Дисертація присвячена вирішенню важливої науково-технічної задачі впливу несинусоїдальних режимів роботи електричних мереж на процеси електроспоживання в точці підключення неідеального (несиметричного і нелінійного) навантаження до мережі з несиметричною і несинусоїдальною напругою. На основі теоретичних досліджень, що використовують єдиний векторний підхід, отримана векторна математична модель несинусоїдальних і несиметричних енергетичних режимів у чотирьохпроводній системі. Векторний підхід використовує два доповнюючих один одного методу: часовий і спектральний метод. Часовий підхід використовує поняття класичної скалярної і нової векторної миттєвої потужності. Спектральний підхід застосовує комплексний ряд Фур'є до трифазних процесів струму і напруги. Підхід використовує класичні поняття скалярних інтегральних потужностей (активна потужність і реактивна потужність) і дозволяє отримати нові інтегральні векторні потужності (потужність небалансу, потужність пульсацій). На прикладі активно-реактивного несиметричного лінійного навантаження показано як запропонована математична модель дозволяє уточнювати і деталізувати розкладання повної потужності IEEE Standard 1459 несинусоїдного режиму. Методом візуального програмування Simulink реалізовано імітаційну модель несинусоїдального енергетичного режиму в пакеті Matlab. Проведене моделювання підтвердило правильність теоретичних досліджень.Thesis for scientific degree of candidate of technical sciences, specialty 05.14.02 – Еlectrical power stations, networks and systems. – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2016. The thesis is dedicated to solution of the important scientific and technical problem of influence of the non-sinusoidal regimes of electric networks operation on the processes of power consumption at the point of connection of a non-ideal (asymmetrical and nonlinear) load to the network with asymmetrical and non-sinusoidal voltage. Based on theoretical studies using a common vector approach, a vector mathematical model of non-sinusoidal and asymmetrical power regimes in a four-phase system has been obtained. The vector approach uses two complementary methods: time and spectral. Time approach uses concepts of the classical scalar and a new vector instant power. The spectral approach uses complex Fourier series for three-phase current and voltage processes. The approach uses the classical notions of scalar integral powers (active power and reactive power) and provides obtaining new integrated vector powers (power of unbalance, power of pulsations). It was shown on an example of activereactive nonsymmetrical linear load how the proposed mathematical model allows refining and detailing the decomposition of full power of the IEEE Standard 1459 non-sinusoidal mode. Imitating model of non-sinusoidal power regime was implemented with the help of visual programming method Simulink in the software package Matlab. Carried simulations have confirmed the correctness of theoretical research.
4
Cester, Christophe. "Étude des pertes magnétiques supplémentaires dans les machines asynchrones alimentées par onduleur à modulation de largeur d'impulsion." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0068.
Повний текст джерелаАнотація:
La banalisation de l'emploi d'onduleras à Modulation de Largeur d'Impulsion pour l'alimentation des machines asynchrones rend indispensable l'étude des pertes magnétiques supplémentaires qu'ils engendrent. L'influence des paramètres principaux de la MLI, fréquence de hachage et paramètre de modulation est étudiée, grâce à un banc de mesure de type cadre Epstein spécialement adapté. L'emploi d'un moteur instrumenté de 4 kW permet d'observer les formes d'ondes réellement présentes dans les différentes parties du circuit magnétique et de montrer que la déformation du signal MLI entraîne une forte augmentation des pertes magnétiques. Le calcul des pertes totales du moteur à partir des formes d'ondes révèle qu'il existe un écart important avec les pertes fer mesurées par la méthode standardisée, car celle-ci ne permet pas une décomposition détaillée des pertes. Une méthode plus précise est donc proposée. Cependant, l'amélioration du calcul des pertes fer passe aussi par une meilleure prise en compte de la géométrie et des phénomènes locaux, que seule une simulation par éléments finis permet d'approcher. Une méthode originale d'estimation des pertes basée sur une caractérisation préalable du matériau dans un large domaine d'inductions et de fréquences est donc présentée. Cette méthode permet de retrouver les cycles d'hystérésis dynamiques dans des conditions d'excitation quelconques. Elle a été associée au logiciel de calcul par éléments finis FLUX2D et appliquée avec succès au calcul des pertes magnétiques dans le stator et le rotor d'une machine asynchrone
Книги з теми "Non-sinusoidal regimes"
1
Provan, Drew, Trevor Baglin, Inderjeet Dokal, Johannes de Vos, and Hassan Al-Sader. Haematopoietic stem cell transplantation. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199683307.003.0009.
Повний текст джерелаАнотація:
Haemopoietic stem cell transplantation (SCT) - Indications for haemopoietic SCT - Allogeneic SCT - Autologous STC - Investigations for BMT/PBSCT - Pretransplant investigation of donors - Bone marrow harvesting - Peripheral blood stem cell mobilization and harvesting - Microbiological screening for stem cell cryopreservation - Stem cell transplant conditioning regimens - Infusion of cryopreserved stem cells - Infusion of fresh non-cryopreserved stem cells - Blood product support for SCT - Graft-versus-host disease (GvHD) prophylaxis - Acute GvHD - Chronic GvHD - Veno-occlusive disease (syn. sinusoidal obstruction syndrome) - Invasive fungal infections and antifungal therapy - CMV prophylaxis and treatment - Post-transplant vaccination programme and foreign travel - Longer term effect post-transplant - Treatment of relapse post-allogeneic SCT - Discharge and follow-up
Тези доповідей конференцій з теми "Non-sinusoidal regimes"
1
Nicolae, Ileana-Diana, Petre-Marian Nicolae, and Radu-Florin Marinescu. "Evaluating the Non-sinusoidal and Non-symmetric Regimes from a Railway Supplying Substation." In 2018 International Power Electronics Conference (IPEC-Niigata 2018-ECCE Asia). IEEE, 2018. http://dx.doi.org/10.23919/ipec.2018.8507949.
Повний текст джерела
2
Metwally, Hossam M., and Raj M. Manglik. "A Computational Study of Enhanced Heat Transfer in Laminar Flows of Non-Newtonian Fluids in Corrugated-Plate Channels." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1277.
Повний текст джерелаАнотація:
Abstract The enhanced heat transfer behavior of laminar shear-thinning, power-law fluid flows in sinusoidal corrugated-plate channels is investigated. With duct plates at uniform wall temperature, periodically developed flows are considered for a wide range of channel corrugation aspect ratio (0 ≤ γ ≤ 1), flow rates (10 ≤ Reg ≤ 1500), and pseudo-plastic flow behavior indices (n = 0.5, 0.8, and 1.0). Typical velocity and temperature distributions, along with extended results for isothermal friction factor f and Collburn factor j are presented. The enhanced forced convection is found to be strongly influenced by γ, and the flow field displays two distinct regimes: undisturbed laminar or no swirl, and swirl flow regimes. In the no-swirl regime, behavior similar to that in fully developed straight duct flows with no cross-stream disturbance is obtained. The shear-thinning nature of the fluid, however, decreases f and enhances j. In the swirl regime, flow separation and reattachment in the corrugation troughs generates transverse vortices that grow with Reg and γ. The transition to this regime is also seen to depend on Reg, γ, and n, and in shear-thinning flows, it occurs at a lower Reg. The combined effects of corrugated plate geometry and non-Newtonian fluid rheology produce a heat transfer enhancement, as measured by the factor j/f, of over 3.3 times that in a flat-plate channel depending upon γ, n, and Reg.
3
Bellizzi, Sergio, Renaud Côte, and Marc Pachebat. "Experimental Study of an Acoustic System Coupled to a Nonlinear Membrane Under Multi-Frequency Forcing." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12817.
Повний текст джерелаАнотація:
In this paper, an experimental study of the coupling of a 2 degree-of-freedom acoustic medium to a nonlinear visco-elastic membrane under multi-frequency forcing is presented. When the excitation is sinusoidal, we observe classical results: non-linear effects tend to damp pressure in the linear system. When the excitation is quasi-periodic with two frequencies, various aspects of quasi-periodic regimes are observed. Some regimes exhibit only the two excitation frequencies in their spectrum, other display a more complicated, but mostly discrete, spectrum. These stable quasi-periodic regimes can disappear leaving to Strongly Modulated Quasi-Periodic Responses (SMQPR). Various structures have been extracted from SMQPRs using signal processing tools (RMS analysis, Fourier analysis, histogram analysis). They are compared with theory and the NES efficiency is assessed. The system behaves in general as expected: the periodic, quasi-periodic or SMQPR regimes correspond to theoretical findings.
4
Andrei, Horia, Costin Cepisca, Sorin Dan Grigorescu, and Paul Andrei. "Sensitivity analysis of the Multiple FeedBack filter in non-sinusoidal regime." In 2010 XIth International Workshop on Symbolic and Numerical Methods, Modeling and Applications to Circuit Design (SM2ACD). IEEE, 2010. http://dx.doi.org/10.1109/sm2acd.2010.5672323.
Повний текст джерела
5
Andrei, H., L. Nastase, E. Diaconu, C. Cepisca, Sorin Dan Grigorescu, and P. Andrei. "Contributions on sensitivity analysis for the analog two-port networks in non-sinusoidal regime." In IEEE EUROCON 2011 - International Conference on Computer as a Tool. IEEE, 2011. http://dx.doi.org/10.1109/eurocon.2011.5929174.
Повний текст джерела
6
Andrei, H., C. Cepisca, and F. Spinei. "The Modelling of the Power Factor in Steady State Non Sinusoidal Regime with Mathcad Techniques." In 2006 IEEE International Conference on Automation, Quality and Testing, Robotics. IEEE, 2006. http://dx.doi.org/10.1109/aqtr.2006.254497.
Повний текст джерела
7
Iacobici, Nicolae Luca, Emil Cazacu, Mihaela Frigura-Iliasa, and Flaviu Mihai Frigura-Iliasa. "Computer Based Analysis for the Parameters of a Distribution Transformer in a Non-Sinusoidal Regime." In 2019 IEEE 17th World Symposium on Applied Machine Intelligence and Informatics (SAMI). IEEE, 2019. http://dx.doi.org/10.1109/sami.2019.8782753.
Повний текст джерела
8
Diga, Silvia-Maria, Nicolae Diga, and Andi-Daniel Grigore. "Particularities of photometric calculation and non-sinusoidal operation regime of luminaires with high pressure sodium vapour lamps." In 2018 Seventh Balkan Conference on Lighting (BalkanLight). IEEE, 2018. http://dx.doi.org/10.1109/balkanlight.2018.8546954.
Повний текст джерела
9
Shojaee Fard, M. H., and A. R. Noorpoor. "Numerical Simulation of Heat and Fluid Flow Behavior in a Pipe Flow With Sinusoidal Boundary Condition." In ASME 2003 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ices2003-0638.
Повний текст джерелаАнотація:
In this investigation a two-dimensional airflow and heat transfer with sinusoidal boundary condition analysis was conducted. Both laminar and turbulent sinusoidal pipe flows were investigated numerically for Remax = 2000, 10000, 20000 and 60000. The results are compared with experimental results of previous investigators [2], [5]. Comparing non-dimensional velocity amplitudes also checks predictions of the flow regime on present sinusoidal flow conditions. A high Reynolds number RNG k-ε turbulence model was used for turbulent flows. An available code, which is basis on finite volume and can solve Nervier-stokes equations on the structured grids, is used. After discrete equations on the control volume, physical properties flux on the control volume by means of first-order upwind difference scheme is calculated. Then, to solve algebraic equations the SIMPLE method is used. Computational results are presented and discussed for velocity, pressure drop, wall shear, temperature, heat flux, and convection coefficient.
10
Wiercigroch, Marian, Mohsen Badiey, Jeffrey Simmen, and Alexander H. D. Cheng. "Bifurcation and Stability Analysis of Parabolic Ray Equations for Acoustic Wave Propagation in an Underwater Sound Channel." In ASME 1995 Design Engineering Technical Conferences collocated with the ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/detc1995-0424.
Повний текст джерелаАнотація:
Abstract The non-linear dynamic behavior of acoustic wave propagation in underwater sound channel is studied by a parabolic ray theory using Munk’s sound speed profile. The Hamiltonian system of the ray trajectory is forced by a single mode sinusoidal internal wave. The amplitude and wave length of this excitation are used in a bifurcation analysis. The regions of instability are located by numerical simulations and visualized through a sequence of phase diagrams and Poincaré maps.