Input Phase Research Articles

A Novel RRR-SVPWM-Based Speed Controlling Mechanism for Brushless DC Motor

Brushless DC motor (BLDCM) is a synchronous motor that contains a permanent magnet on the rotor and armature windings on the stator. It consists of the following characteristics, such as compact form, high efficient, silent operations and low maintenance. The existing BLDCM control systems have some drawbacks such as, it needs higher requirements for control algorithms, it uses more complicated electronics, it holds high noise and the initial rotor movement is not predictable. In order to overcome these issues, a new control mechanism, namely, carrier frequency rate, duty cycle ratio and pulse position range-space vector pulse width modulation (RRR-SVPWM) technique is proposed in this paper to control the speed of BLDCM. Initially, the unregulated AC from the wind turbine system is given to the input of six-legs insulated gate bipolar transistor (IGBT) circuit for converting the unregulated AC to regulated DC. Here, the pulse generator is used to generate the pulses based on certain parameters, such as input three-phase voltage, phase current and DC voltage. Hence, the proposed RRR-SVPWM technique is applied to reduce the noise and maintain a harmonics in a controlled level by placing a high-speed switches in a circuit. Finally, the speed of the BLDCM is increased and controlled by giving an output regulated AC to the motor. The experimental results evaluate the performance of the proposed system in terms of power factor (PF), displacement PF (DPF) and total harmonic distortion (THD).

Phase analysis method for burst onset prediction.

The response of bursting neurons to fluctuating inputs is usually hard to predict, due to their strong nonlinearity. For the same reason, decoding the injected stimulus from the activity of a bursting neuron is generally difficult. In this paper we propose a method describing (for neuron models) a mechanism of phase coding relating the burst onsets with the phase profile of the input current. This relation suggests that burst onset may provide a way for postsynaptic neurons to track the input phase. Moreover, we define a method of phase decoding to solve the inverse problem and estimate the likelihood of burst onset given the input state. Both methods are presented here in a unified framework, describing a complete coding-decoding procedure. This procedure is tested by using different neuron models, stimulated with different inputs (stochastic, sinusoidal, up, and down states). The results obtained show the efficacy and broad range of application of the proposed methods. Possible applications range from the study of sensory information processing, in which phase-of-firing codes are known to play a crucial role, to clinical applications such as deep brain stimulation, helping to design stimuli in order to trigger or prevent neural bursting.

A Biased Look at Phase Locking: Brief Critical Review and Proposed Remedy

A number of popular measures of dependence between pairs of band-limited signals rely on analytic phase. A common misconception is that the dependence revealed by these measures must be specific to the spectral range of the filtered input signals. Implicitly or explicitly, obtaining analytic phase involves normalizing the signal by its own envelope, which is a nonlinear operation that introduces broad spectral leakage. We review how this generates bias and complicates the interpretation of commonly used measures of phase locking. A specific example of this effect may create spurious phase locking as a consequence of nonzero circular mean in the phase of input signals, which can be viewed as spectral leakage to 0 Hz. Corrections for this problem which recenter or uniformize the distribution of phase may fail when the amplitudes of the compared signals are correlated. To address the more general problem of spectral bias, a novel measure of phase locking is proposed, the amplitude-weighted phase locking value (awPLV). This measure is closely related to coherence, but it removes ambiguities of interpretation that detract from the latter.

DockingApp: a user friendly interface for facilitated docking simulations with AutoDock Vina.

Molecular docking is a powerful technique that helps uncover the structural and energetic bases of the interaction between macromolecules and substrates, endogenous and exogenous ligands, and inhibitors. Moreover, this technique plays a pivotal role in accelerating the screening of large libraries of compounds for drug development purposes. The need to promote community-driven drug development efforts, especially as far as neglected diseases are concerned, calls for user-friendly tools to allow non-expert users to exploit the full potential of molecular docking. Along this path, here is described the implementation of DockingApp, a freely available, extremely user-friendly, platform-independent application for performing docking simulations and virtual screening tasks using AutoDock Vina. DockingApp sports an intuitive graphical user interface which greatly facilitates both the input phase and the analysis of the results, which can be visualized in graphical form using the embedded JMol applet. The application comes with the DrugBank set of more than 1400 ready-to-dock, FDA-approved drugs, to facilitate virtual screening and drug repurposing initiatives. Furthermore, other databases of compounds such as ZINC, available also in AutoDock format, can be readily and easily plugged in.

The Use of Frequency Characteristics for Interconnected Drive of Rolling Mill Modes Research

When modeling complex interrelated facilities, the MATLAB environment may not always be useful for determination of frequency response characteristics. This fact may be explained by properties of facilities, which can change their parameters at variable operation conditions. The authors propose a model of rating frequency response characteristics for the above facilities to determine an amplitude response as relation of amplitudes of input and output sine waveforms and a phase delay between an input and output signal (phase curve) at different values of input frequencies. The proposed method was used for evaluation of frequency response characteristics of interrelated electric drives of the continuous rolling mill, where strip properties in the inter-stand gap depend on the rolling speed. The investigation outcome may be used at designing tension regulators for continuous rolling mills.

A Novel Dual-Broadband Dual-Polarized Electrical Downtilt Base Station Antenna for 2G/3G Applications

A novel dual-broadband dual-polarized base station antenna array with compact structure and low profile is proposed in this paper for the existing mobile communication system operating over 0.79–0.96 GHz (European Digital Dividend/CDMA/GSM) and 1.71–2.17 GHz (DCS/PCS/UMTS). The antenna array is mainly composed of five lower-band elements, ten upper-band elements, some U-shaped metal baffles, and a metal reflector with specific shape. In order to reduce the overall size of the antenna array, lower-band element is designed as octagon aperture shape that upper-band elements can be embedded in it. Two kinds of radiation elements (five for each kind of element) are applied in the antenna array as upper-band elements to achieve better radiation performance. The proposed antenna array achieves electrical downtilt (0°–14° and 0°–10° at lower frequency band and upper frequency band, respectively) by adjusting input amplitude and phase of each array element. Measured results demonstrate that the antenna array has good broadside radiation characteristics, including low voltage standing wave ratio (VSWR 28 dB), low backlobe level (>25 dB), high cross-polarization discrimination (>20 dB), and stable radiation pattern with horizontal half-power beamwidth (HPBW) 65° ± 5° at both frequency bands and all electrical downtilt angles. The peak gains of 15.1 and 17.3 dBi are obtained at lower and upper bands respectively. Owing to these advantages, the antenna array is suitable for existing 2G/3G applications in modern mobile communication systems.

Dark GPC: extended nodal beam areas from binary-only phase

We show a simplified method of generating extended regions of destructive interference with near arbitrary shapes using the generalized phase contrast (GPC) method. For Gaussian input beams, GPC typically results in a 3× intensified user-defined input mask shape against a dark background. In this work, we investigate conditions wherein GPC’s synthetic reference wave destructively interferes with what is typically the foreground pattern. Using alternate conditions for the input phase mask, the locations of light and darkness are interchanged with respect to typical GPC output mappings. We show experimentally how “dark GPC” allows the dark regions to be easily reshaped using a binary-only phase mask encoded on a spatial light modulator. Similar to standard GPC, the method does not require complex calculations or the fabrication of complex gray-level phase elements. The simplified approach and flexibility in the output shapes make dark GPC attractive for applications such as optical trapping of low-index particles or superresolution microscopy like stimulated emission depletion.

Common-Mode Voltage Reduction for Matrix Converters Using All Valid Switch States

This paper presents a new space vector modulation (SVM) strategy for matrix converters to reduce the common-mode voltage (CMV). The reduction is achieved by using the switch states that connect each input phase to a different output phase, or the switch state that connects all the output phases to the input phase with minimum absolute voltage. These two types of states always produce lower peak CMV than the others, especially the former ones that result in zero CMV at the output side of matrix converters. In comparison with the existing SVM methods, this strategy has a very similar software overhead and calculation time. Simulation and experiment results are shown to validate the effectiveness of the proposed modulation method in reducing not only the peak value but also the root-mean-square value of the CMV.

RF-Input Self-Outphasing Doherty–Chireix Combined Amplifier

A new design method for Doherty–Chireix combined operation is proposed. Only one of the two amplifiers operates at the low power region like a Doherty amplifier, while both amplifiers are operating as a Chireix outphasing amplifier at the high power region, taking advantage of the high efficiency region of each operating mode. Quasi-envelope efficiency of both amplifier efficiency curves is extracted in a systematic way using only analog circuit design methods. The output combiner is used as an input splitter for the radio frequency input Chireix outphasing without using any digital signal processing. Input signal phase control versus power for outphasing operation is obtained by using only a linear circuit, exploiting the input impedance variation of nonideal devices. A 52.4-dBm peak output power, 6.6-dB back-off Doherty–Chireix combined amplifier, is built operating at 2.17 GHz. A 50% average power added efficiency was measured using 6-dB peak-to-average power ratio, 3.84 MHz modulated test signals. Class-B like efficiency behavior is obtained at the low power region without compromising the peak back-off efficiency.

A Doherty Power Amplifier Design Method for Improved Efficiency and Linearity

A novel Doherty power amplifier (PA) design method enabling high efficiency and high linearity simultaneously is proposed. The output combiner network is treated as a black box, and its parameters, together with the input phase delay, are solved based on given transistor characteristics and design requirements. This opens for new PA solutions with nonconventional Doherty behavior. The increased design space enables new tradeoffs in Doherty PA designs, including solutions with both high efficiency and high linearity simultaneously. A method utilizing the new design space is developed. For verification, a 20-W 2.14-GHz symmetrical gallium nitride high electron mobility transistors Doherty PA is fabricated and measured. The PA obtains an average power added efficiency of 40% and an adjacent power leakage ratio of −41 dBc without any linearization for an 8.6-dB peak to average power ratio 10-MHz-long term evolution signal, at an average output power of 35.5 dBm.

Miniaturization of a 90° Hybrid Coupler with Improved Bandwidth Performance

This letter presents a compact hybrid coupler having wider bandwidth compared to a conventional 90° branch line coupler. Coupling between two closely spaced branches is utilized for the improvement. Closed form expressions are derived using a lossless transmission line theory. Further, graphs are presented to determine size of the coupler with the required bandwidth specifications. In the bandwidth calculation, input matching, isolation, phase and amplitude imbalances, all conditions are considered simultaneously. A coupler is fabricated on a 1.58 mm thick FR4 substrate. It occupies 33% area of a conventional branch line coupler. The measured fractional bandwidths for the input matching, isolation, phase and amplitude imbalance conditions are 19.6%, 12.4%, 41.9% and 35.2%, respectively, which is higher than a conventional one.

Mixing Oscillators for Phase Noise Reduction

The output of oscillators is usually not stable over time. In particular, phase variations---or \emph{phase noise}---corrupts the oscillations. In this letter, we describe a circuit that designed to average the phase noise processes and frequency offsets in frequency-matched oscillators. The basic circuit uses the independence of 2 phase noise processes to provide a cleaner oscillating output with lower phase noise variance. We describe extensions of the circuit designed to average out more than 2 oscillators, as well as a single one through delay elements. In all the examples covered, we provide a theoretical analysis of the resulting phase noise process when the input phase noise processes follow a Wiener model.

Hypocretin/Orexin Peptides Alter Spike Encoding by Serotonergic Dorsal Raphe Neurons through Two Distinct Mechanisms That Increase the Late Afterhyperpolarization

Orexins (hypocretins) are neuropeptides that regulate multiple homeostatic processes, including reward and arousal, in part by exciting serotonergic dorsal raphe neurons, the major source of forebrain serotonin. Here, using mouse brain slices, we found that, instead of simply depolarizing these neurons, orexin-A altered the spike encoding process by increasing the postspike afterhyperpolarization (AHP) via two distinct mechanisms. This orexin-enhanced AHP (oeAHP) was mediated by both OX1 and OX2 receptors, required Ca(2+) influx, reversed near EK, and decayed with two components, the faster of which resulted from enhanced SK channel activation, whereas the slower component decayed like a slow AHP (sAHP), but was not blocked by UCL2077, an antagonist of sAHPs in some neurons. Intracellular phospholipase C inhibition (U73122) blocked the entire oeAHP, but neither component was sensitive to PKC inhibition or altered PKA signaling, unlike classical sAHPs. The enhanced SK current did not depend on IP3-mediated Ca(2+) release but resulted from A-current inhibition and the resultant spike broadening, which increased Ca(2+) influx and Ca(2+)-induced-Ca(2+) release, whereas the slower component was insensitive to these factors. Functionally, the oeAHP slowed and stabilized orexin-induced firing compared with firing produced by a virtual orexin conductance lacking the oeAHP. The oeAHP also reduced steady-state firing rate and firing fidelity in response to stimulation, without affecting the initial rate or fidelity. Collectively, these findings reveal a new orexin action in serotonergic raphe neurons and suggest that, when orexin is released during arousal and reward, it enhances the spike encoding of phasic over tonic inputs, such as those related to sensory, motor, and reward events. Orexin peptides are known to excite neurons via slow postsynaptic depolarizations. Here we elucidate a significant new orexin action that increases and prolongs the postspike afterhyperpolarization (AHP) in 5-HT dorsal raphe neurons and other arousal-system neurons. Our mechanistic studies establish involvement of two distinct Ca(2+)-dependent AHP currents dependent on phospholipase C signaling but independent of IP3 or PKC. Our functional studies establish that this action preserves responsiveness to phasic inputs while attenuating responsiveness to tonic inputs. Thus, our findings bring new insight into the actions of an important neuropeptide and indicate that, in addition to producing excitation, orexins can tune postsynaptic excitability to better encode the phasic sensory, motor, and reward signals expected during aroused states.

Mechanisms and functional roles of glutamatergic synapse diversity in a cerebellar circuit.

Synaptic currents display a large degree of heterogeneity of their temporal characteristics, but the functional role of such heterogeneities remains unknown. We investigated in rat cerebellar slices synaptic currents in Unipolar Brush Cells (UBCs), which generate intrinsic mossy fibers relaying vestibular inputs to the cerebellar cortex. We show that UBCs respond to sinusoidal modulations of their sensory input with heterogeneous amplitudes and phase shifts. Experiments and modeling indicate that this variability results both from the kinetics of synaptic glutamate transients and from the diversity of postsynaptic receptors. While phase inversion is produced by an mGluR2-activated outward conductance in OFF-UBCs, the phase delay of ON UBCs is caused by a late rebound current resulting from AMPAR recovery from desensitization. Granular layer network modeling indicates that phase dispersion of UBC responses generates diverse phase coding in the granule cell population, allowing climbing-fiber-driven Purkinje cell learning at arbitrary phases of the vestibular input.

Effect of input phase modulation to a phase-sensitive optical amplifier.

Many optical applications depend on amplitude modulating optical beams using devices such as acousto-optical modulators (AOMs) or optical choppers. Methods to add amplitude modulation (AM) often inadvertently impart phase modulation (PM) onto the light as well. While this PM is of no consequence to many phase-insensitive applications, phase-sensitive processes can be affected. Here we study the effects of input phase and amplitude modulation on the output of a quantum-noise limited phase-sensitive optical amplifier (PSA) realized in hot 85Rb vapor. We investigate the dependence of PM on AOM alignment and demonstrate a novel approach to quantifying PM by using the PSA as a diagnostic tool. We then use this method to measure the alignment-dependent PM of an optical chopper which arises due to diffraction effects as the chopper blade passes through the optical beam.

Memristor based BPSK and QPSK demodulators with nonlinear dopant drift model

In this paper, the dependence of the instantaneous memristance value and its I–V characteristics on a periodic signal phase are studied. Hence, expression for the instantaneous memristance as a function of the periodic input phase is derived. This derivation is based on the memristor linear dopant drift model and is provided for sinusoidal input waveforms. To prove the tendency, simulations using linear and nonlinear dopant drift memristor models are performed in the Cadence simulation environment. Based on those, a set of digital communication demodulators are proposed and investigated exploiting the change of the average memristance with the initial phase of applied signal. The experimental-based ‘nonlinear’ dopant drift model is used in designing the proposed demodulators for Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK) modulation schemes. Since all proposed demodulators are asynchronous, the proposed circuits do not need any carrier recovery circuits. Moreover, transient simulations have been executed showing the proper matching to the expected performance.

Design of a Broadband HEMT Mixer for UWB Applications

Background/Objectives: Microwave mixer is a crucial element in virtually all transmits and receives systems. Methods/Statistical analysis: In this paper, a novel distributed HEMT mixer with three layers is designed for Ultrawide-Band (UWB) receivers. We employ external capacitors in the proposed circuit to adjust the output phase shift between stages to equal the input phase shift. Findings: The simulation results show that the proposed structure, achieves vary broadband performances in Converstion Gain, Power Consumption and LO-RF Isolation, comparable to the recent reported cascode or dual-gate distributed mixers. With a local oscillator power of 12 dBm and RF power of -20 dBm, our mixer has a Conversion Gain of 0 ~ 4 dB (without IF signal amplification), LO-to-RF isolation better than 32 dB and 130 mW DC power consumption over bandwith 5-25 GHz. Applications/Improvements: In our scheme, an intermediate layer is considered to increase LO-RF Isolation and improve the Converstion Gain criterion. Moreover, Microstrip lines are used to form the artificial gate and drain transmission lines as well as phase equalization of the signal on drain transmission line.

QPSK 3R regenerator using a phase sensitive amplifier.

A black box phase sensitive amplifier based 3R regeneration scheme is proposed for non-return to zero quadrature phase shift keyed formatted signals. Performance improvements of more than 2 dB are achieved at the presence of input phase distortion.

Coherent Absorption of N00N States.

Recent results in deeply subwavelength thickness films demonstrate coherent control and logical gate operations with both classical and single-photon light sources. However, quantum processing and devices typically involve more than one photon and nontrivial input quantum states. Here we experimentally investigate two-photon N00N state coherent absorption in a multilayer graphene film. Depending on the N00N state input phase, it is possible to selectively choose between single- or two-photon absorption of the input state in the graphene film. These results demonstrate that coherent absorption in the quantum regime exhibits unique features, opening up applications in multiphoton spectroscopy and imaging.

WEIGHTED LEAST SQUARE SAR AUTOFOCUSING TECHNIQUE (WLS).

The Weighted Least Squares (WLS) autofocus algorithm has been widely used in spotlight Synthetic Aperture Radar (SAR) for phase error estimation to compensate motion-induced blurs in the images. The WLS autofocus algorithm has proven to be a superior method for higher order autofocusing because it can be used to estimate all kinds of phase errors, no matter whether they are of low order, high order or random. Compared with other methods, the WLS estimation is optimal in the scene that it has the minimum variance of the estimated error. In this paper, a proposed PC-based software model of the WLS autofocus algorithm is introduced. Simulation results between blurred and focused images, or between the input phase error function and the estimated one carried out by calculating the root mean square (rms) value of the residual phase error, show significant removal of high-order phase errors and better removal of the low-order phase errors. Finally, a suggested Graphical User Interface (GUI) of the proposed algorithm for easier handling on PC-based equipment is introduced. SAR WLS MOCO GUI. [M. Adel Ahmed. (2016); WEIGHTED LEAST SQUARE SAR AUTOFOCUSING TECHNIQUE (WLS). Int. J. of Adv. Res. 4 (Jun). 1506-1511] (ISSN 2320-5407). www.journalijar.com Mohammed Adel Ahmed Abdelhamid Shoukry