scholarly journals Directed harmonic currents near hyperbolic singularities

2017 ◽  
Vol 38 (8) ◽  
pp. 3170-3187 ◽  
Author(s):  
VIÊT-ANH NGUYÊN
Keyword(s):  
Mass Distribution ◽  
Holomorphic Foliation ◽  
Holomorphic Foliations ◽  
Harmonic Current ◽  
Lelong Number ◽  
Harmonic Currents ◽  
Hyperbolic Singularity ◽  
Compact Complex Surfaces ◽  
Global Result ◽  
Local Result

Let $\mathscr{F}$ be a holomorphic foliation by curves defined in a neighborhood of $0$ in $\mathbb{C}^{2}$ having $0$ as a hyperbolic singularity. Let $T$ be a harmonic current directed by $\mathscr{F}$ which does not give mass to any of the two separatrices. We show that the Lelong number of $T$ at $0$ vanishes. Then we apply this local result to investigate the global mass distribution for directed harmonic currents on singular holomorphic foliations living on compact complex surfaces. Finally, we apply this global result to study the recurrence phenomenon of a generic leaf.

scholarly journals Directed harmonic currents for laminations on certain compact complex surfaces

2014 ◽  
Vol 25 (04) ◽  
pp. 1450032 ◽  
Author(s):  
Carlos Pérez-Garrandés
Keyword(s):  
Riemann Surfaces ◽  
Complex Surfaces ◽  
Harmonic Current ◽  
Complex Torus ◽  
Harmonic Currents ◽  
Compact Complex Surfaces ◽  
Closed Current

Let ℒ be a Lipschitz lamination by Riemann surfaces embedded in M. If M is a complex torus, ℂℙ1 × ℂℙ1 or 𝕋1 × ℂℙ1 and there is no directed closed current then there exists a unique directed harmonic current of mass one. Moreover, if ℒ is embedded in M = ℂℙ1 × ℂℙ1 and has no compact leaves, then there is no directed closed current. If ℒ is not Lipschitz, then slightly weaker results are obtained.

scholarly journals A Novel Method for Harmonic Current Injection with Sensor Supported Adaptation on Permanent Magnet Synchronous Machines

Machines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 139
Author(s):  
Matthias Vollat ◽  
Dominik Krahe ◽  
Frank Gauterin
Keyword(s):  
Permanent Magnet ◽  
Current Injection ◽  
Synchronous Machines ◽  
Permanent Magnet Synchronous Machine ◽  
Permanent Magnet Synchronous Machines ◽  
Harmonic Current ◽  
Harmonic Currents ◽  
Sensor Signals ◽  
Novel Method ◽  
Higher Harmonic

To reduce torque oscillations in electric motors, harmonic current injection (HCI) has been used in industry for some time. For this purpose, higher harmonic currents calculated in advance are injected into the machine. Since the general conditions for the machine can change during its life cycle, this article presents a method that makes it possible to change the parameters of HCI during operation. For this purpose, sensor signals are used to detect the reaction of the electric motor to small variations of the HCI parameters. The knowledge gained in this way is used to make further suitable variations. FEM simulations were used to verify the effectiveness of the approach. The results show that the algorithm can independently optimize the HCI parameters during runtime and reduces the amplitude of the 6th harmonic in the torque by 87% for a permanent magnet synchronous machine.

Smart Switching Power Supply with Input Voltage Waveform Correction

2014 ◽  
Vol 614 ◽  
pp. 245-248
Author(s):  
You Chen Yuan ◽  
Meng Wang ◽  
Yu Wei Chen
Keyword(s):  
Power System ◽  
Power Transmission ◽  
Voltage Drop ◽  
Power Grid ◽  
Input Voltage ◽  
Voltage Waveform ◽  
Harmonic Current ◽  
Switching Power ◽  
Harmonic Currents ◽  
Smart Control

The technology of smart control rectifier is introduced in this paper, in which the harmonic currents in power system is reduced and the voltage waveform is compensated. The voltage waveform in power system is measured by microcontroller, and is compared with the standard sinusoidal voltage waveform and the error voltage is obtained which contains the information of harmonic current waveform. The error voltage is employed to control the input current of the rectifier, and the reverse components of harmonic current is involved in the power side current of the appliance, by this means to get rid of some of the harmonic currents in power grid. Harmonic current will produce a voltage drop on the resistance in power transmission line to make the voltage waveform distortion happen; and the reduction of the harmonic current will shrink the distortion of voltage waveform. Taking a capacitive soft switching flyback push-pull converter as an example, the experimental circuit and the testing system are designed; the software programming and circuit debugging are accomplished. The experimental results show that the smart control rectifier can absorb harmonic currents from the power grid when operating in rectification, and to get the input voltage waveform corrected.

scholarly journals Harmonic Current Suppression of Dual Three-Phase PMSM Based on Model Predictive Direct Torque Control

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Bicheng Lei ◽  
Lingwei Wu ◽  
Zhiming Lin ◽  
Pan Mei
Keyword(s):  
Direct Torque Control ◽  
Torque Control ◽  
Vector Group ◽  
Harmonic Current ◽  
Loop Control ◽  
Harmonic Currents ◽  
Voltage Vector ◽  
Three Phase ◽  
The Cost ◽  
Spatial Distribution Characteristic

The traditional direct torque control (DTC) method will produce a larger harmonic current in the x, y subspace when applied to a dual three-phase permanent magnet synchronous machine (DTP-PMSM) because the voltage vector used for DTC is not equal to zero in the x, y harmonic subspace. To mitigate this problem, in this manuscript, a model predictive direct torque control (MPDTC) method is proposed to eliminate the harmonic current in DTP-PMSM. The spatial distribution characteristic DTP-PMSM voltage vector is analyzed; then, the table of vector group can be obtained according to DTC, and each vector group can be combined to obtain the zero-voltage vector in the x, y subspace. According to the cost function, MPDTC selects the vector group and obtains the optimal vector sequence combination to eliminate the harmonic current in the x, y subspace. Furthermore, the MPDTC achieves closed-loop control of harmonic currents in the x, y subspace. The MPDTC can also eliminate harmonic currents caused by other factors. The simulation results show that the method of MPDTC can effectively suppress the harmonic current of DTP-PMSM.

Research on the Control Method of High Power APF for Oil Drilling Rig

2013 ◽  
Vol 734-737 ◽  
pp. 1450-1459
Author(s):  
Neng Qian Jiang ◽  
Ming Hua Zhu ◽  
Yi Feng Xie
Keyword(s):  
Control Strategy ◽  
Control Method ◽  
Electrical Equipment ◽  
Current Control ◽  
Harmonic Current ◽  
Oil Drilling ◽  
Drilling Rig ◽  
Harmonic Currents ◽  
Domain Transformation ◽  
And Control

The wide use of oil drilling rig brings nominated economic profits for oil drilling industry. However, it will bring about great quantities of harmonic current to the grid, lowering the power quality and reliability of the power grid. Meanwhile, harmonic currents will have a deteriorated influence to surrounding electrical equipment and grid. This paper studies the distribution characteristics of the harmonic current in the oil industry and puts forward a control strategy aiming for improving stability and reliability of the power supply system. This paper also proposes an algorithm for detecting harmonic current based on time domain transformation and control strategy based on two cascade (voltage and current) control loop. Experiment and simulation results validate the proposed control strategy.

ON THE SINGULAR SCHEME OF CODIMENSION ONE HOLOMORPHIC FOLIATIONS IN ℙ3

2010 ◽  
Vol 21 (07) ◽  
pp. 843-858 ◽  
Author(s):  
LUIS GIRALDO ◽  
ANTONIO J. PAN-COLLANTES
Keyword(s):  
Singular Locus ◽  
The Other ◽  
Holomorphic Foliation ◽  
Holomorphic Foliations ◽  
Codimension One ◽  
Other Hand ◽  
Tangent Sheaf ◽  
Torsion Free

In this work, we begin by showing that a holomorphic foliation with singularities is reduced if and only if its normal sheaf is torsion-free. In addition, when the codimension of the singular locus is at least two, it is shown that being reduced is equivalent to the reflexivity of the tangent sheaf. Our main results state on one hand, that the tangent sheaf of a codimension one foliation in ℙ3 is locally free if and only if the singular scheme is a curve, and that it splits if and only if it is arithmetically Cohen–Macaulay. On the other hand, we discuss when a split foliation in ℙ3 is determined by its singular scheme.

HOLOMORPHIC FOLIATIONS AND CHARACTERISTIC NUMBERS

2005 ◽  
Vol 07 (05) ◽  
pp. 583-596 ◽  
Author(s):  
MARCIO G. SOARES
Keyword(s):  
Projective Space ◽  
Complex Manifold ◽  
Complex Projective Space ◽  
Holomorphic Foliation ◽  
Compact Complex Manifold ◽  
Holomorphic Foliations ◽  
Singular Set ◽  
One Dimensional ◽  
Characteristic Numbers ◽  
Complex Projective

We relate the characteristic numbers of the normal sheaf of a k-dimensional holomorphic foliation [Formula: see text] of a compact complex manifold Mn, to the characteristic numbers of the normal sheaf of a one-dimensional holomorphic foliation associated to [Formula: see text]. In case M is a complex projective space, we also obtain bounds for the degrees of the components of codimension k - 1 of the singular set of [Formula: see text].

scholarly journals A NON-EXISTENCE THEOREM FOR MORSE TYPE HOLOMORPHIC FOLIATIONS OF CODIMENSION ONE TRANSVERSE TO SPHERES

2010 ◽  
Vol 21 (04) ◽  
pp. 435-452 ◽  
Author(s):  
TOSHIKAZU ITO ◽  
BRUNO SCARDUA
Keyword(s):  
Existence Theorem ◽  
Affine Space ◽  
Holomorphic Foliation ◽  
Holomorphic Foliations ◽  
Codimension One ◽  
Concentric Spheres ◽  
Linear Foliation

We prove that a Morse type codimension one holomorphic foliation is not transverse to a sphere in the complex affine space. Also we characterize the variety of contacts of a linear foliation with concentric spheres.

scholarly journals Identifikasi Penjalaran Gelombang Panjang Samudera Hindia Ke Selat Lombok Berdasarkan Komponen Harmonik Arus

Omni-Akuatika ◽  
2016 ◽  
Vol 12 (1) ◽  
Author(s):  
Yogo Pratomo ◽  
Widodo Setiyo Pranowo ◽  
Hendrawan Setiadi
Keyword(s):  
Indian Ocean ◽  
Internal Wave ◽  
Time Series Data ◽  
Current Speed ◽  
Ocean Current ◽  
Series Data ◽  
Harmonic Current ◽  
Harmonic Currents ◽  
Long Wave ◽  
Through Flow

The Lombok Strait is one area passing by seawater mass from Pacific Ocean to Indian Ocean, well known as Indonesia Through Flow (ARLINDO). It was profen by the existane of long periode harmonic current component affected by the sun (SA, SSA ) , and an influence by moon (MSF). The harmonic current speed has an average of 0.370668 m/s in the depths of 100 meters during January 9, 2004 until 14 June 2005 (1.5 years). Time series data ocean current of INSTANT project (2004-2005) is used in this research, analized by using toolbox module of t-tide 1.3 beta. The current rose at 350 meters deep and 450 meters deep shous pattern of the a unique ocean current, which mastly toward to north and northeast (55 %) with velocity at 0.2-1.0 m/s. The current is coming from Indian Ocean which proven by the existence of components like M4, MS4, MSF, O1. There is also ocean current toward to south and southwest as (45 %) with speed of 0.11-0.9 m/s. Thie ocean current which coming from Indian Ocean is indication of propagation of long wave penetration to Lombok Strait. During its propagation passing the sill, the wave become an internal wave in Lombok Strait.Keywords: internal wave, indian ocean, lombok strait, harmonic currents component, INSTANT 2004-2005

scholarly journals A Study of K- Factor Power Transformer Characteristics by Modeling Simulation

2011 ◽  
Vol 1 (5) ◽  
pp. 114-120 ◽  
Author(s):  
O. E. Gouda ◽  
G. M. Amer ◽  
W. A. A. Salem
Keyword(s):  
Power Transformer ◽  
Thermal Capacity ◽  
Power Transformers ◽  
Nonlinear Loads ◽  
Harmonic Current ◽  
Premature Failure ◽  
Modeling Simulation ◽  
Harmonic Currents ◽  
K Factor

Harmonic currents generated by nonlinear loads can cause overheating and premature failure in power transformers. K-factor transformers are specially designed to accommodate harmonic currents and offer protection against overheating caused by harmonics. They minimize harmonic current loss and have an additional thermal capacity of known limits. According to IEEE C57-110, the winding eddy current losses are considered proportional to the harmonic current squared times its harmonic number. K-factor is only an indicative value and the authors' main objective in this paper is to study the effect of harmonics on oil filled transformer and to simulate harmonic behavior using Matlab Simulink. A case study is simulated in order to investigate K-factor values with pumping loads, with and without the use of harmonic filters. Results are compared with measured values.

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