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In this paper, we provide a survey of dynamic spectrum access techniques. Various approaches envisioned for dynamic spectrum access are broadly categorized under three models: dynamic exclusive use model, open sharing model, and hierarchical access model. Based on this taxonomy, we provide an overview of the technical challenges and recent advances under each model.Show More
Generally speaking, the article abstractly describes some points of view on further improving of the spectrum efficiency. At first, the author- introduces the current spectrum circumstance and the traditional method of doing this in China. Then the importance of raising the spectrum efficiency and some technical methods are analyzed in the article. The strategy of the spectrum management and the s...Show More
All high-voltage installations are subject to a series of legislation and regulations to limit the permitted noise levels. Considering area, levels are divided into public areas, areas of increased sensitivity and occupational exposure areas. In addition, it is well known that there is a connection between load harmonics and noise in certain frequency spectrum. In order to investigate this phenome...Show More
Dynamic spectrum access (DSA), which represents a paradigm shift away from the current static spectrum allocation approach, has been identified as a promising approach in the near future. This paper presents the taxonomy of DSA, focuses on the characteristics of three models and describes current research status of American XG project, IEEE 802.22 standard and European End-to-End Efficiency (E3) p...Show More
The problem on evaluating the harmonic amplitudes resulting from the summation of various non-linear loads is not yet properly addressed, mainly because, in general, the studies are based on the load's characteristic harmonic spectrum, taken as fixed and invariable, as listed in the literature. The second aspect is the vain attempt to find an also fixed weighting mean and deterministically set to ...Show More
This paper investigates current harmonic emissions and the nature and the manifestation of the electromagnetically induced vibration signature in wound rotor induction machines. The strength and consistency of harmonic signatures between three industrial WRIMs with different design parameters is examined. A numerical harmonic model is used to predict and investigate WRIMs' stator and rotor current...Show More
This paper investigates the impact of supply harmonic voltages on DFIG stator current and power spectra. The influence of individual higher order supply harmonics on DFIG stator current and on total instantaneous power spectral content is investigated using a time-stepped circuit model. The observed effects are identified in experimental data obtained from a laboratory test rig. A set of analytica...Show More
Dynamic spectrum access (DSA) is a novel mechanism designed to increase the utilization of the radio spectrum. This paper presents a review of state-of-art with the references to the relevant works in the area of DSA. The most important DSA models and the main related challenges are introduced. Dynamic exclusive use model of DSA serves as the underlying platform for the implementation of spectrum ...Show More
Motor current signature analysis (MCSA) has been widely used in motor fault detection including bearing fault, broken-bar, and eccentricity, etc. When a motor’s fault is in its early stage or a faulty motor is operating in varying load conditions, fault signature may be submerged in the background noise and interference, making fault detection a very challenging problem. In this paper, we address ...Show More
Dynamic spectrum access technologies such as cognitive radio aim to improve the current spectrum utilisation by allowing opportunistic spectrum access to the licensed frequency bands without causing interference. However, in order to this, better understanding of the spectrum usage pattern is important. In this context, this paper presents the 24-hour spectrum survey of an outdoor radio environmen...Show More
A novel soluble zinc phthalocyanine-bisphenol A epoxy derivative (ZnPc-DGEBPA) was synthesized and characterized by infrared (IR), electronic absorption spectra and fluorescence spectra. Electronic absorption spectrum of ZnPc-DGEBPA exhibited characteristic absorption peaks at 367 nm and 710 nm. Fluorescence emission peak was at 458 nm and quantum yield reached 0.33 in N, N-dimethylformamide (DMF)...Show More
In recent years, demand for wireless communication services has grown far beyond earlier predictions, raising serious concerns about future radio spectrum shortages. Current spectrum management policy is characterised by static spectrum allocation where radio spectrum is allocated on a long term for large geographical regions on exclusive basis. This is an effective way to prevent interference, bu...Show More
Cognitive Internet of Vehicles (CIoV) can improve spectrum utilization by accessing the spectrum licensed to primary user (PU) under the premise of not disturbing the PU's transmissions. However, the traditional static spectrum access makes the CIoV unable to adapt to the various spectrum environments. In this paper, a reinforcement learning based dynamic spectrum access scheme is proposed to impr...Show More
This paper characterises wave and current fields at two different marine energy site with investigation of WCIs (wave current interactions) and turbulence. The features of a 5-beam ADCP are utilised whereby it is found to accurately measure wave spectra up to high frequencies as well as providing directional wave data. Deployments were conducted in 2010 and 2011 using a Teledyne RDI 5-beam ADCP (A...Show More
Current transformers for ac power systems applications are usually calibrated by applying sinusoidal currents at different frequencies. The main limitation of this approach is that it does not take into account nonlinearities that may have a significant impact on harmonic current measurement. A more accurate characterization should be based on test currents that are similar to those found in norma...Show More
The performance and operational feasibility of the high-frequency Wellen Radar Doppler radar have been demonstrated in a region dominated by strong tidal currents during the SURveillance LITtorale OPerationnelle experiment in Brittany (France). Local weather-oceanic phenomena (current-wave-wind interactions) were measured for the first time by temporal-spatial analyses of the sea surface current m...Show More
This paper provides a method and a system based on current pulse excitation and frequency spectrum analysis, which can complete battery impedance spectrum test and analysis. By exerting current excitation onto the battery, synchronously measuring current excitation and terminal voltage response, we count the amplitude spectrum and phase spectrum for current excitation and terminal voltage response...Show More
This paper investigates the spectral effects that stator supply harmonics can induce in wound rotor and doubly-fed induction generators. The purpose of this study is to clarify the nature and the origin of the reported significant inter harmonic effects in these machines. To this end, the authors derive analytical expressions that define the spectral signature frequencies of individual supply harm...Show More
Electronic conductance and quantum current distribution of C60 molecular device connected to different terminals are investigated theoretically by using nonequilibrium Green's function approach based on tight-binding theory. The electronic transmission spectra of the C60 molecule from an input terminal to the near- and the far-output terminals are obtained, respectively. The quantum currents insid...Show More
In this document we analyze business model of the spectrum spot market scenario, which involves novel spectrum sharing mechanisms for the mobile services delivery. Based on the proposed scenario and spectrum management mechanisms, we describe new revenue opportunities for network operators and discuss its influence on the strategy of the current key market players.Show More
This paper provides an overview of radio spectrum monitoring in borderlands of China. Firstly research background, the motivation, accomplishments are described and then plans for future work in China are presented. Current radio spectrum monitoring systems are man-machine communication systems based on Radio Monitoring Transfer Protocol (RMTP), which are unable to detect and process the radio int...Show More
In view of the current direct sequence spread spectrum underwater acoustic communication has become an important detection object of underwater acoustic non-cooperative communication detection, based on the analysis of the applicability of the current three mainstream underwater acoustic spread spectrum communication detection methods in the offshore complex multipath and low signal-to-noise ratio...Show More

Voltage and current spectra for a single-phase voltage source inverter

IMA Journal of Applied Mathematics
Year: 2009 | Volume: 74, Issue: 5 | Journal Article |
Cited by: Papers (9)
An inverter converts a direct current power supply to an alternating current power supply. To do so, its output is switched at high frequency between the inputs in order to synthesize the desired alternating current output in the low-frequency part of the Fourier spectrum. Here, we calculate analytical expressions for the input and output current and voltage spectra for two inverter designs: so-ca...Show More
An analytical description combined with finite-element calculations of the current displacement caused by short-circuit current impulses in 1-D and 2-D conductor models is presented. It is shown that in many cases, the Joule integral used in the technical practice gives a false representation of the thermal stress in the conductors and contacts. A simplified method is given for determining the deg...Show More
The most popular means of protection against indirect contact in low voltage systems is automatic disconnection of supply, since it is a simple and economically attractive way to achieve safety in an electrical installation. As a protective device, residual current devices (RCDs) are commonly used. In certain conditions using the RCDs is obligatory. The widespread application of static converters,...Show More