Asymmetric Source Research Articles

Asymmetric hearing loss in industry

Asymmetric hearing loss in industry

Parámetros que Afectan la Corriente de Neutro en Presencia de Armónicos

This work analyzes potentials variables that affect neutral currents when the receptors connected present nonlinear characteristics. Different scenarios were simulated in the Alternative Transients Program combining the type and number of load units, successively fed with sinusoidal, symmetric, balanced, asymmetric and unbalanced power supply voltage. The effect of harmonics on source voltage was also studied. Field measurements were registered in a computer center to contrast results. A variation of up to 5% in the neutral current was registered as product of the simulations with asymmetric and unbalanced sources. The analysis of the diversity effect showed variations of a little more than 10% whereas the attenuation effect caused a 20% reduction. The results show that the asymmetries and unbalances in the feeding sources have a slight incidence on neutral currents, whereas the diversity and attenuation effects are more important.

Non-Parametric Generalized Cross Entropy Estimator for Bss Algorithm

Generalized cross entropy estimator (GCEE)-based non-parametric blind signal separation (BSS) algorithm is proposed under the framework of natural gradient (NG) optimization method. To improve the performance of signal separation by BSS, the probability distribution of source signals must be described as accurately as possible. Compared to the non-parametric fixed-width kernel density estimator (FKDE) method, the GCEE with a new data-driven bandwidth selection method can improve the performance of FKDE, which is inspired by the principles of the generalized cross entropy method. Moreover, the direct estimation of the score functions can separate the hybrid mixture of sources that contain both symmetric and asymmetric distribution source signals and do not need to assume the parametric non-linear functions of them. The effectiveness of the proposed algorithm has been confirmed by simulation experiments.

Do Gravity Waves Transport Angular Momentum away from Tropical Cyclones?

Abstract Previous studies have suggested that gravity waves can transport a significantly large amount of angular momentum away from tropical cyclones, as much as 10% of the core angular momentum per hour. These previous studies used the shallow-water equations to model gravity waves radiating outward from rapidly rotating inner-core asymmetries. This issue is reinvestigated with a three-dimensional, nonhydrostatic, linear model of the vortex-anelastic equations. The response of balanced, axisymmetric vortices modeled after tropical cyclones to rotating asymmetric heat sources is examined to assess angular momentum transport by gravity waves radiating away from the core region of the vortices. Calculations show that gravity waves do transport angular momentum away from the vortex core; however, the amount transported is several orders of magnitude smaller than recent estimates.

On the Sum-Capacity of Degraded Gaussian Multiple-Access Relay Channels

The sum-capacity is studied for a K-user physically degraded Gaussian multiple-access relay channel (MARC). Decode-and-forward (DF) is shown to achieve the sum-capacity and capacity region for a subclass of degraded Gaussian MARCs in which the multiple-access link from the sources to the relay is the bottleneck link. For the remaining subclass, DF is shown to achieve the K-user sum-capacity when the sources are symmetric, i.e., they transmit with the same transmit power. The optimality of DF is conjectured for the case of asymmetric sources.

Nanoscale Contacts between Carbon Nanotubes and Metallic Pads

It is well-known that the electrical properties and performance of carbon nanotube field-effect transistors (CNTFETs) are largely dominated by their nanotube/metal contacts. Such nanometer-scaled contacts are typically different from traditional bulk semiconductor/metal contacts, as a thin layer of molecules could be unintentionally introduced between the CNTs and metal electrodes through either adsorption of environmental molecules or device fabrication processes. Here, we present a nanocontact model, in which the energy band bending in the CNTs near the contacts is quantitatively characterized through establishment of electrostatic charge balance between the CNTs and metallic pads under the influences of environmental oxygen. The concept of dipole polarization along the CNT channel in the FET geometry is, for the first time, introduced in order to interpret puzzling findings from several CNT Schottky transistors with asymmetric source and drain contacts.

Sourcing for Supplier Effort and Competition: Design of the Supply Base and Pricing Mechanism

We study a buyer's sourcing strategy along two dimensions: the supply base design and the pricing mechanism, considering supplier competition and cost-reduction e ffort. The supply base design concerns the number of suppliers (one or two) included in the supply base, and the capacity to be invested in each supplier. The pricing mechanism determines the timing of the price decisions, with the buyer making price commitments before suppliers exert cost-reduction eff orts that may be renegotiated afterwards. We fi nd that symmetric capacity investment in suppliers and low price commitments (more likely to be renegotiated) are eff ective at fostering supplier competition, while asymmetric investment and high price commitments (less likely to be renegotiated) are better at motivating supplier e ffort. A complementary relationship exists between the supply base design and pricing mechanism: A more symmetric supply base should be combined with lower price commitments leading to more renegotiation opportunities. This results in three possible sourcing structures: sole sourcing (investing capacity in a single supplier and forming price with ex ante commitments), symmetric dual sourcing (investing equal capacity in both suppliers and forming price with ex post negotiations), and asymmetric dual sourcing (investing positive but unequal capacities in two (ex ante identical) suppliers and forming price using both ex ante commitments and ex post (re)negotiations). We characterize the conditions for each structure, and identify a strategic role of capacity investment.

Chirality emergence in thin solid films of amino acids by polarized light from synchrotron radiation and free electron laser.

One of the most attractive hypothesis for the origin of homochirality in terrestrial bioorganic compounds is that a kind of “chiral impulse” as an asymmetric excitation source induced asymmetric reactions on the surfaces of such materials such as meteorites or interstellar dusts prior to the existence of terrestrial life (Cosmic Scenario). To experimentally introduce chiral structure into racemic films of amino acids (alanine, phenylalanine, isovaline, etc.), we irradiated them with linearly polarized light (LPL) from synchrotron radiation and circularly polarized light (CPL) from a free electron laser. After the irradiation, we evaluated optical anisotropy by measuring the circular dichroism (CD) spectra and verified that new Cotton peaks appeared at almost the same peak position as those of the corresponding non-racemic amino acid films. With LPL irradiation, two-dimensional anisotropic structure expressed as linear dichroism and/or linear birefringence was introduced into the racemic films. With CPL irradiation, the signs of the Cotton peaks exhibit symmetrical structure corresponding to the direction of CPL rotation. This indicates that some kinds of chiral structure were introduced into the racemic film. The CD spectra after CPL irradiation suggest the chiral structure should be derived from not only preferential photolysis but also from photolysis-induced molecular structural change. These results suggest that circularly polarized light sources in space could be associated with the origin of terrestrial homochirality; that is, they would be effective asymmetric exciting sources introducing chiral structures into bio-organic molecules or complex organic compounds.

Efficient time-domain algorithm for calculation of harmonic currents produced by a cluster of AC/DC converters with the consideration of load variations

A useful time-domain algorithm to characterise harmonic currents produced by a cluster of three-phase AC/DC converters operated under either balanced or imbalanced supply voltages and asymmetrical source impedances with the consideration of load variations is proposed. The proposed method is based on the Poincareacute map concept for increasing the solution speed. An actual industrial rolling mill system with several DC motor drives operating in parallel is under test to show the usefulness of the proposed method. Simulations results are compared with those obtained by actual measurements. It shows that the harmonic currents determined by the proposed method agree well with those obtained by actual measurements. The proposed algorithm is relatively accurate, computationally efficient and robust.

Asymmetric Schottky Tunneling Source SOI MOSFET Design for Mixed-Mode Applications

Schottky barrier MOSFETs have recently attracted attention as a viable alternative to conventional CMOS transistors for sub-65-nm technology nodes. An asymmetric Schottky tunneling source SOI MOSFET (STS-FET) is proposed in this paper. The Schottky tunneling source SOI MOSFET has the source/drain regions replaced with silicide as opposed to highly doped silicon in conventional devices. The main feature of this device is the concept of a gate-controlled Schottky barrier tunneling at the source. The device was optimized with respect to various parameters such as Schottky barrier height and gate oxide thickness. The optimized device shows excellent short channel immunity, compared to conventional SOI MOSFETs. The asymmetric nature of the device has been shown to improve the leakage current as well as the linear characteristics of the device as compared to conventional Schottky FETs. The STS-FET was fabricated, using conventional processes combined with the present NiSi technology and large angle implantation, and successfully demonstrated. The high immunity to short channel effects improves the scalability, and the output resistance of the device also makes it an attractive candidate for mixed-mode applications.

Coverage expandable current type code controlled DCC with TDC-based range selector

Coverage expandable current type code controlled DCC is presented, which has TDC-based range selector. The TDC-based range selector is composed of the TDC, the anti-harmonic lock block and the encoder/decoder. The code controlled current source has asymmetric current source to both current sinks for duty error correction and is controlled by binary digital codes. And the DCC amplifier controlled by binary codes has switches which are selected according to the input frequency range. With the frequency range information, the DCC amp can expand the cover range with suitable bit resolutions. The proposed circuit is designed and simulated with 54nm CMOS technology. The DCC circuit can correct at least duty error of 6% from 500MHz through 1.25GHz.

Theoretical study of the performance for short channel carbon nanotube transistors with asymmetric contacts

We have simulated short channel carbon nanotube field-effect transistors with asymmetric source and drain contacts using a coupled mode space approach within the non-equilibrium Green's function framework. The simulated results show that the asymmetric conduction properties under positive and negative drain-to-source voltages are caused by the asymmetric Schottky barriers to carriers at the source and drain contacts. Under negative drain-to-source voltages, hole and electron conduction are dominated by thermionic emission and tunneling through the Schottky barrier, respectively, leading to the different subthreshold behaviors of the hole and electron conduction. With increasing channel length, short channel effects can be suppressed effectively and ON/OFF ratio can be improved.

Inverse Analysis of Heat Conduction in Hollow Cylinders with Asymmetric Source Distributions

This paper presents an application of inverse analysis for determining both the temperature field histories and corresponding heat source distributions in hollow cylinders. The primary goal, however, is the development of an inversion infrastructure in a manner that allows taking advantage of all aspects related to its utility, including sensitivity analysis. The conditions generating heat sources are those resulting from intense pulsed-current electrical contact experiments. Under these conditions intense heat currents are generated due to the Joule conversion of the electric conduction currents. Asymmetry of the heat source is induced from the localized melting due to arc-enhanced electric conduction. Experimentally acquired temperature histories and melting domain boundary data are utilized to setup an inverse model of the heat conduction problem. This permits the construction of an estimate not only of the temperature field histories throughout the computational domain but also of an evaluation of the effective thermal diffusivity of the material involved.

Determining the irradiance signal from an asymmetric source with directional detectors: application to calibrations of radiometers with diffusers

The energy transfer integral between radiating rectangular and detecting circular parallel plates having nonideal angular characteristics is solved for modeling the distance dependence of the irradiance signal. The equation derived for the irradiance signal, which is called the modified inverse-square law, depends on the position, shape, size, and angular characteristics of the light source and the detector. We apply the new model equation to the calibration of a spectroradiometer to determine accurately the distance offsets, which fix the positions of the effective receiving apertures of diffusers used in the entrance optics of spectroradiometers. Earlier measurement results, e.g., for solar UV irradiance, may include uncorrected effects and can be corrected reliably as diffuser offsets and other correction factors are determined with the modified inverse-square law. Simplifications of the modified inverse-square law for analyzing the distance offsets and the correction factors are studied. Simplified equations for the diffuser offset analysis may be used without losing the accuracy when the cosine response of the diffuser is reasonably good. However, for diffusers whose angular responsivities deviate much from the cosinusoidal angular responsivity, large approximation errors in the diffuser offset values may appear if the angular effects are not properly taken into account.

Boundary instability of a two-dimensional electron fluid

It was shown previously that the current-carrying state of a Field Effect Transistor with asymmetric source and drain boundary conditions may become unstable against spontaneous generation of plasma waves [1]. By extending the analysis to the two-dimensional case we find that the dominant instability modes correspond to waves propagating in the direction perpendicular to the current and localized near the boundaries. This new type of instability should result in plasma turbulence with a broad frequency spectrum. More generally, it is shown that a similar instability might exist, when a strong enough current goes through a single boundary between the gated and ungated regions.

Three‐phase distributed constants model of induction machines for EMC and surge propagation studies

PurposeThis paper aims to provide a complete three‐phase distributed constants model of cable‐induction machine systems useful for EMC and overvoltages propagation studies.Design/methodology/approachThe paper considers a three‐phase distributed constants model for the supply cable and a model of the same type for the induction machine. All the magneto‐electric links between phases are considered. The Clarke transform is applied in order to reduce the analytical complexity of the obtained model. A new numerical method is also proposed for the integration of the resulting whole three‐phase model, very similar, in terms of methodology, to the well‐known finite differences models.FindingsThe whole model for the three‐phase drives is used for EMC and overvoltages propagation studies. The proposed examples highlight how, thanks to the Clarke model, the dynamic analysis of the three‐phase drives in case of application of a standard fault source or an equivalent pulse width modulation (PWM) impulse, become easy to implement on a standard PC and with standard software (i.e. Matlab). The obtained results, compared with those that are presented in the literature, confirm the validity of the proposed model and numerical approach.Originality/valueThe developed model is of a three‐phase type because it is not possible to consider a single‐phase equivalent model in case of asymmetric voltage sources (i.e. asymmetric faults or PWM inverter voltage supply). The model also includes all the magneto‐electric couplings between phases that play a fundamental role in the considered applications.

Quantum Dot Nanodevice with Electron-Lattice Coupling

AbstractThe electronic current-voltage characteristics of a nanotransistor is studied. The nanotransistor is assumed to consist of a quantum dot active region connected to the source and drain wires and also attached to a gate. The electric current is shown to be influenced by the coupling of electrons to the longitudinal optical phonons, namely, by the up-conversion of the electrons to the higher excited states in a quantum dot, due to a nonadiabatic effect of the lattice vibrations. In the nanotransistor with asymmetric source and drain contacts the up-conversion leads to a spontaneous electric current, or to a spontaneous voltage between the electrodes. We remind existing experiments which might be related to the effect considered.

Unique Carbon-Nanotube Field-Effect Transistors with Asymmetric Source and Drain Contacts

We have fabricated a type of unique single-walled carbon nanotube field-effect transistor, in which the channel length is only 90 nm and aluminum and gold are used as its drain and source electrodes, respectively. The channel conductance oscillations caused by single-electron tunneling through the asymmetric barriers at the drain and source contacts are observed up to 100 K. Above 100 K, the tunneling fades away, and thermionic emission dominates the conductance at sufficiently negative gate voltages. At room temperature, the device shows diode-like characteristics with a maximum current rectification ratio of approximately 10(4).

Tropical Cyclone Intensification from Asymmetric Convection: Energetics and Efficiency

Abstract Prior studies of the linear response to asymmetric heating of a balanced vortex showed that the resulting intensity change could be very closely approximated by computing the purely symmetric response to the azimuthally averaged heating. The symmetric response to the purely asymmetric part of the heating was found to have a very small and most often negative impact on the intensity of the vortex. This result stands in contrast to many previous studies that used asymmetric vorticity perturbations, which suggested that purely asymmetric forcing could lead to vortex intensification. The issue is revisited with an improved model and some new methods of analysis. The model equations have been changed to be more consistent with the anelastic approximation, but valid for a radially varying reference state. Expressions for kinetic and available potential energies are presented for both asymmetric and symmetric motions, and these are used to quantify the flow of energy from localized, asymmetric heat sources to kinetic energy of the wind field of the symmetric vortex. Previous conclusions were based on simulations that used instantaneous temperature perturbations to represent rapid heat release in cumulus updrafts. Purely asymmetric heat sources that evolve over time and move with the local mean wind are shown to also cause vortex weakening. Weakening of the symmetric vortex is due to extraction of energy by the evolving asymmetries that undergo significant transient growth due to downgradient transport of momentum across the radial and vertical shears of the symmetric wind field. While much of this energy is returned during the axisymmetrization of the resulting potential vorticity anomalies, there is typically a net loss of energy for the symmetric vortex. Some variations on the rotation rate and duration of the heat sources can lead to intensification rather than weakening, as does a deeper (more barotropic) vertical structure of the symmetric vortex. However, it is reaffirmed that these asymmetrically forced changes are small compared to the response to the azimuthally averaged heating of an isolated heat source. Following the work of Hack and Schubert, the efficiency of the intensification process, defined as the ratio of injected heat energy to the kinetic energy change of the symmetric vortex, is computed for vortices of different sizes and strengths. In the limit of small perturbations, the efficiency does not depend on the temporal distribution of the heating. The efficiency is shown to increase with the intensity of the vortex and with the Coriolis parameter, with substantial efficiency increases for weak vortices. Potential applications of these results for predicting tropical cyclone formation and rapid development are discussed.

Investigation on a New Algorithm for Instantaneous Reactive and Harmonic Currents Detection Applied to Intensive Nonlinear Loads

To pursue an improved solution to instantaneous reactive power and harmonics compensation with intensively nonlinear and quasistochastic loads, an effective algorithm is presented with comprehensive integration of the i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> -i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</sub> and p-q methods to detect instantaneous reactive and harmonic currents. The algorithm can be applicable in three-phase circuits of any operational conditions, including three-phase four-wire circuits, asymmetric and/or harmonic voltage sources, etc. Both theoretical deduction and computer simulations demonstrate the accuracy and feasibility of the algorithm. Also, the above algorithm is expanded for further applications, which can effectively realize extraction and decomposition of the active or reactive components of either positive-sequence or negative-sequence currents with respect to any order harmonics.