Input-output Phase Research Articles

Modeling and Analysis of Duhem Hysteresis Operators With Butterfly Loops

In this work we study and analyze a class of Duhem hysteresis operators that can exhibit butterfly loops. We study firstly the consistency property of such operator which corresponds to the existence of an attractive periodic solution when the operator is subject to a periodic input signal. Subsequently, we study the two defining functions of the Duhem operator such that the corresponding periodic solutions can admit a butterfly input-output phase plot. We present a number of examples where the Duhem butterfly hysteresis operators are constructed using two zero-level set curves that satisfy some mild conditions.

Improving the stability of phase retrieval algorithm in speckle autocorrelation imaging by Huber penalty sparsity constraint

One of the most widely used methods for reconstructing images through a scattering medium is the Hybrid Input Output (HIO) phase retrieval algorithm. However, the stability and noise robustness of the HIO method are poor, as they are affected by initial values and noise during the imaging process. This paper presents an optimized HIO phase retrieval algorithm that utilizes the Huber penalty as a sparsity constraint to effectively enhance the quality and stability of the reconstruction algorithm. The introduced constraint is designed to guide the iteration process away from local optimal solutions, ensuring superior recovery images even with random initial values. Additionally, an adaptive step size parameter is incorporated to control the iterations and convergence steps, resulting in stronger robustness against noise effects. Moreover, the error criterion for image restoration is defined as the sum of the Fourier transform amplitude of the gradient. Experimental results demonstrate that the proposed phase retrieval algorithm achieves superior quality in the recovered images, while significantly improving noise immunity and stability for randomly selected initial values.

A 2.4–8 GHz Phase Rotator Delay-Locked Loop Using Cascading Structure for Direct Input–Output Phase Detection

This paper presents a phase rotator (PR)-based delay-locked loop (DLL) for a dynamic random-access memory interface in 28-nm CMOS technology. A direct input-output comparison using a sub-sampling technique reduces the effect of a timing mismatch of a replica delay line for synchronizing an input clock and output strobe clock. A divided clock samples the input clock for phase alignment. A 4-b analog-to-digital converter was used for input phase acquisition. The output phase is aligned with respect to the sampling clock phase using a bang-bang phase detector. Two DLLs for the input-output synchronization are implemented in a cascade structure, and the loop delay of the replica delay line is considerably reduced. In the proposed DLL, a PR delay line using an 8-phase clock generator is adopted for linearity to reduce the phase difference of the phase interpolation from π/2 to π/4. The resolution of the PR-DLL is 7-b of 2π, which consists of a 3-b coarse and a 4-b fine control. The DLL operates from 2.4 to 8 GHz, and the power dissipation at the maximum input frequency is 20.2 mW. The measured clock root mean square jitter was 1.68 ps. According to the simulation results, the phase mismatch between the input and output clocks was reduced by 80.5%.

High-Frequency SiC-Based Inverters With Input Stages Based on Quasi-Z-Source and Boost Topologies—Experimental Comparison

This paper contains a comparison between three topologies of a three-phase two-level inverter: A quasi-Z-source inverter (qZSI), a voltage-source inverter with a boost converter and a voltage-source inverter with an interleaved boost converter. experimental results obtained from laboratory tests of equivalent 6-kW 100-kHz inverters based on SiC mosfet s and Schottky diodes are provided. The following parameters are compared: Quality of input inductor current and output phase voltage as well as total power losses in the inverters. The results for these parameters are obtained for input voltage ranging from 325 V to almost 600 V (where feasible), for two sets of equivalent modulation methods (two regular methods and two reduced-loss methods), for a couple of characteristic values of deadtime and for the operation both at the maximum value of modulation index and at equal values of voltage across the inverter bridge. Results of the experiments show that the qZSI topology may, at certain conditions, surpass the traditional two-stage inverter topologies in the areas of input inductor current quality, output voltage quality and also power losses (at high values of input voltage). What is needed to obtain that is a careful examination of operating conditions, applied modulation method and deadtime value.

New Nonlinear Second-Order Phase-Locked Loop with Adaptive Bandwidth Regulation

Synchronization of large acquisition bandwidth brings great challenges to the traditional second-order phase-locked loop (PLL). To address the contradiction between acquisition bandwidth and noise suppression capability of the traditional PLL, a new second-order PLL coupled with a nonlinear element is proposed. The proposed nonlinear second-order PLL regulates the loop noise bandwidth adaptively by the nonlinear module. When a large input–output phase error occurs, this PLL reduces the frequency offset quickly by taking advantage of the large bandwidth. When the phase error is reduced by the loop control, the proposed PLL suppresses noises by using the small bandwidth to increase the tracking accuracy. Simulation results demonstrate that the tracking speed of the proposed PLL is increased considerably, and its acquisition bandwidth is increased to 18.8 kHz compared with that of the traditional second-order PLL (4 kHz).

A 12 GHz 22 dB-Gain-Control SiGe Bipolar VGA With 2° Phase-Shift Variation

A 12 GHz VGA showing a gain variation range from $-9\;\text{dB}$ to $13\;\text{dB}$ with a linear-in-dB gain control feature is presented in this work. As the gain is changed, the phase shift over the entire 10–14.4 GHz bandwidth varies as little as $\leq$ 2° due to a compensation circuitry that reduces the input-output phase shift sensitivity to gain variations in a robust manner with respect to temperature changes. Such a reduced phase shift variation is particularly useful to simplify the signal phase/amplitude control for the various paths of a phased array system, and allows to implement ultra-low sidelobe phased arrays. The VGA prototypes, implemented in a SiGe bipolar technology, show a noise figure of 5.1 dB, an IIP3 of $- 3\;{\rm dBm}$ , a ${P_{1{\rm dB}}}$ of $- 17\; \text{dBm}$ , and a power consumption of 83 mW.

Quantitative Imaging of Single Unstained Magnetotactic Bacteria by Coherent X-ray Diffraction Microscopy.

Novel coherent diffraction microscopy provides a powerful lensless imaging method to obtain a better understanding of the microorganism at the nanoscale. Here we demonstrated quantitative imaging of intact unstained magnetotactic bacteria using coherent X-ray diffraction microscopy combined with an iterative phase retrieval algorithm. Although the signal-to-noise ratio of the X-ray diffraction pattern from single magnetotactic bacterium is weak due to low-scattering ability of biomaterials, an 18.6 nm half-period resolution of reconstructed image was achieved by using a hybrid input-output phase retrieval algorithm. On the basis of the quantitative reconstructed images, the morphology and some intracellular structures, such as nucleoid, polyβ-hydroxybutyrate granules, and magnetosomes, were identified, which were also confirmed by scanning electron microscopy and energy dispersive spectroscopy. With the benefit from the quantifiability of coherent diffraction imaging, for the first time to our knowledge, an average density of magnetotactic bacteria was calculated to be ∼1.19 g/cm(3). This technique has a wide range of applications, especially in quantitative imaging of low-scattering biomaterials and multicomponent materials at nanoscale resolution. Combined with the cryogenic technique or X-ray free electron lasers, the method could image cells in a hydrated condition, which helps to maintain their natural structure.

Plagiarism as an illusional sense of authorship: The effect of predictability on source attribution of thought

Previous studies have shown that contextually high-predictability ideas are essential for one to sense the authorship of thoughts and that having the sense that one came up with an idea of one's own, instead of through hearing of another's idea, results in the feeling that one has output the ideas. In this study, we investigated the effects of an idea's predictability on the misattribution of another's thought to oneself. The participants were asked to write down two original ideas about how to use various objects while avoiding the duplication of another's ideas that had been presented beforehand in an input–output phase. In the monitoring phase (1week and 1month after the input–output phase), the participants were asked whether each idea had been generated by them, by another, or not generated at all. We found that a high-predictability idea is likely to be regarded with the notion “I generated the idea.” This tendency increased with time, suggesting that participants were more likely to have a sense of authorship when high-predictability ideas were presented. We also discovered that they were more likely to conclude that the source of high-predictability ideas was the “Self.” We discussed the results from the viewpoint of the participant's sense of agency as well.

ST Quasi Z-소스 인버터의 스트레스 저감과 출력전압 특성

This paper proposes a ST(Switched Trans) quasi Z-source inverter using a Switched Trans Cell combing the characteristics of a Switched Inductor Cell and Trans. A DC link inductor of the conventional quasi Z-source inverter is alternated with Switched Trans Cell of the proposed ST quasi Z-source inverter. Trans Cell of the proposed method consists of one Trans and two diodes, and the proposed method has higher and more various boost function than the conventional quasi Z-source inverter by simply changing the turns ratio of primary and secondary of the Trans. The validity of the proposed ST Z-source inverter was confirmed by PSIM simulation and a DSP based experiment under the input voltage 48V and output phase voltage 30V. As a result, when compared with the traditional quasi Z-source inverter, the proposed method has the advantage of the low voltage stress under the same output voltage condition of the voltage.

Exploration of crystal strains using coherent x-ray diffraction

We measured coherent x-ray diffraction (CXD) on zeolite microcrystals in order to gain information on internal density distribution and to learn more about the strain developed during the synthesis and attachment process on the substrate. From the distortion and asymmetry of the diffraction pattern on the (020) Bragg peak, the strain field distribution is estimated. We inverted the diffraction patterns from a less strained crystal to obtain the three-dimensional image of the shape and internal strain fields using the error reduction and hybrid input–output phase retrieval algorithms. We also show a few examples of characteristic distortion modes relevant to CXD of zeolites.

Amplitude and phase characterization of nonlinear mixing products

This paper discusses the problem of amplitude and phase characterization of nonlinear mixing products arising from a broad class of nonlinear microwave devices. Realizing that the most difficult problem stands on the phase measurement, it starts by reviewing the most common approaches used for the phase characterization of spectral regrowth components. It is demonstrated that these methods can be viewed as correlation processes, and are so framed in a common theory. This allows a unique and universal definition of the input-output amplitude and phase relations, even for mixing products that fall on frequency positions for which there are no components present at the input, and for those arising from incommensurate excitations. Finally, it shows how that theory can be implemented in a laboratory measurement scheme, thus giving the introduced theoretical variables a practical engineering value

Combining global and multi-scale features in a description of the solar wind-magnetosphere coupling

Abstract. The solar wind-magnetosphere coupling during substorms exhibits dynamical features in a wide range of spatial and temporal scales. The goal of our work is to combine the global and multi-scale description of magnetospheric dynamics in a unified data-derived model. For this purpose we use deterministic methods of nonlinear dynamics, together with a probabilistic approach of statistical physics. In this paper we discuss the mathematical aspects of such a combined analysis. In particular we introduce a new method of embedding analysis based on the notion of a mean-field dimension. For a given level of averaging in the system the mean-filed dimension determines the minimum dimension of the embedding space in which the averaged dynamical system approximates the actual dynamics with the given accuracy. This new technique is first tested on a number of well-known autonomous and open dynamical systems with and without noise contamination. Then, the dimension analysis is carried out for the correlated solar wind-magnetosphere database using vBS time series as the input and AL index as the output of the system. It is found that the minimum embedding dimension of vBS - AL time series is a function of the level of ensemble averaging and the specified accuracy of the method. To extract the global component from the observed time series the ensemble averaging is carried out over the range of scales populated by a high dimensional multi-scale constituent. The wider the range of scales which are smoothed away, the smaller the mean-field dimension of the system. The method also yields a probability density function in the reconstructed phase space which provides the basis for the probabilistic modeling of the multi-scale dynamical features, and is also used to visualize the global portion of the solar wind-magnetosphere coupling. The structure of its input-output phase portrait reveals the existence of two energy levels in the system with non-equilibrium dynamical features such as hysteresis which are typical for non-equilibrium phase transitions. Further improvements in space weather forecasting tools may be achieved by a combination of the dynamical description for the global component and a statistical approach for the multi-scale component.Key words. Magnetospheric physics (solar wind– magnetosphere interactions; storms and substorms) – Space plasma physics (nonlinear phenomena)

Phase control approach to hysteresis reduction

The paper describes a method for the design of compensators able to reduce hysteresis in transducers, as well as two measures to quantify and compare controller performance. Rate independent hysteresis, as represented by the Preisach model of hysteresis, is seen as an input-output phase lag. The compensation is based on controllers derived from the phaser, a unitary gain operator that shifts a periodic signal by a single phase angle. A variable phaser is shown to be able to handle minor hysteresis loops. Practical implementations of these controllers are given and discussed. Experimental results exemplify the use of these techniques.

ENCODING CARRIER AMPLITUDE MODULATIONS VIA STOCHASTIC PHASE SYNCHRONIZATION

The firings of excitable systems can phase lock to periodic forcing. In many situations however, the firings are separated by a random number of forcing cycles, even though they occur near a preferred phase of the forcing. Also, the associated interspike interval histograms display peaks over a continuous range of integer multiples of the forcing period, and the peak heights are a unimodal function of increasing multiples of the period. This paper focusses on these patterns of stochastic phase synchronization and their alteration by physiologically relevant stimuli that modulate the amplitude of the periodic forcing. Specifically, two regimes of the FitzHugh–Nagumo system exhibiting stochastic phase locking are considered. We discuss how internal noise, originating from e.g. synaptic or conductance fluctuations, must interact with either suprathreshold or subthreshold dynamics, and in some instances with subthreshold chaos, to produce such firing patterns. These responses to constant amplitude "carriers" are then compared to those from carriers with random band-limited amplitude modulations (AM's). The comparison is based on the mean firing rate, as well as phase synchronization computed using a suitably defined input–output phase difference. Further, using the stimulus reconstruction technique to characterize synchrony between random AM's and spikes, the internal noise is shown to help transmit information about random carrier AM's in the subthreshold and slightly suprathreshold cases. This transmission also depends nonmonotonically on the carrier frequency. Our results provide biophysical insight into the dynamics of neural signal encoding that combines a mean rate code on long time scales and a precise temporal code based on phase locking on the shorter time scale of the carrier period.

Theory of stochastic resonance in signal transmission by static nonlinear systems

A deterministic periodic signal plus a stationary random noise is applied to a static nonlinearity taking the form of a monovariable arbitrary function on real numbers. The property of noise-enhanced signal transmission through stochastic resonance is studied for this class of static nonlinear systems. A theory is developed that provides expressions for the output autocorrelation function, power spectral density, signal-to-noise ratio, and input-output phase shift, in the presence of a periodic input, a noise distribution, and a static nonlinearity, all three being arbitrary. Both white and colored input noises are successively considered. For white input noise, exact expressions are derived in a discrete-time framework directly confrontable to simulations or experiments. The theory is applied to describe stochastic resonance in various examples of static nonlinear systems, for instance, a diode nonlinearity. In addition, confrontations with experiments and simulations are given that support the theory. In particular, interesting effects are reported such as a signal-to-noise ratio larger at the output than at the input or stochastic resonance at zero frequency. Finally, the validity of the theory is extended to dynamic nonlinear systems that can be decomposed into a static nonlinearity followed by an arbitrary dynamic linear system. @S1063-651X~97!12002-5#

Simultaneous AM-AM/AM-PM distortion measurements of microwave transistors using active load-pull and six-port techniques

A programmable active load-pull measurement system using two six-port reflectometers and three passive two-port standards has been developed to obtain load-pull contours of the transistor's input-output phase shift variations over a wide dynamic range of the input power. The output power, gain, power-added efficiency, and phase shift are measured simultaneously at the transistor's input and output reference planes. The phase distortion versus input power, /spl phi//spl sim/P/sub in/, and the AM-PM conversion coefficient at various power levels, k/spl sim/P/sub in/, are obtained for different load impedances by post-measurement calculations. A NE8001 MESFET is tested at f=1.7 GHz for the class A operation. The experimental results are also given.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Neuronal coding of linear motion in the vestibular nuclei of the alert cat. III. Dynamic characteristics of visual-otolith interactions.

In the present study we have investigated in the awake cat the response dynamics of vestibular nuclei neurons to visual or/and otolith stimulation elicited by vertical linear motion. Of the 53 units tested during sinusoidal motion at 0.05 Hz (9.1 cm/s), 1 (1.9%) was responsive to the otolith input only, 13 (24.5%) were influenced by the visual input only and 23 (43.4%) responded to both modalities. Neurons were excited either during upward or downward animal or visual surround movement. Most units displayed a firing rate modulation very close to motion velocity. All the neurons receiving convergent visual and otolith inputs (0.05 Hz, 9.1 cm/s) exhibited synergistic patterns of response. Motion velocity coding was improved in terms of input-output phase relationship and response sensitivity when visual and otolith signals were combined. Depending on the units, visual-otolith interactions in single neurons could follow a linear or a nonlinear mode of summation. The dynamic characteristics of visual-otolith interactions were examined in the 0.05 Hz-0.50 Hz frequency bandwidth. Visual signals seemed to predominate over otolith signals at low stimulus frequencies (up to 0.25 Hz), while the contrary was found in the higher frequency range of movement (above 0.25 Hz). The effects of visual stabilization (VS: suppression of visual motion cues) was observed in a small sample of units. As a rule, VS induced a reduction in the amplitude of unit response as compared to visual + otolith stimulation, the lower the motion frequency, the more pronounced the attenuation. VS also decreased the amplitude of the otolith-dependent component of response. The possible modes of visual-vestibular interactions in single cells are discussed. The present study supports the hypothesis that visual and vestibular motion cues are weighted according to their internal relevance.

Input Variable Assignment and Output Phase Optimization of PLA's

A PLA minimization system having the following features is presented: 1) minimization of both two-level PLA's and PLA's with two-bit decoders; 2) optimal input variable assignment to the decoders; 3) optimal output phase assignment; and 4) essential prime implicants detection without generating all the prime implicants.

Phase relationships and power gains of a SUPARAMP with a correlated double-sideband input

The input-output phase relationships for the doubly degenerate superconducting unbiased parametric amplifier (SUPARAMP) are given. The general analysis is performed for the case when the information is injected into both the signal and idler input channels of the amplifier and the phases of the signal, idler, and pump waves are correlated. The expressions for the phase-dependent power gains are evaluated. The operation for a double-sideband input with symmetry and the usual single-sideband input is treated as a special case. Double-sideband input operation may result in an effective increase of the output signal-to-noise ratio. Another improvement in the signal processing can be achieved by synchronous detection of the SUPARAMP's output.

Cyclic phasing clutch using a cardan drag link

A cyclic phasing clutch is described. An inertia load is driven such that one or more integral revolution of the load can be lost, while the input shaft continues to rotate at a constant speed. No input-output phase change is experienced with revolution loss. The machine has inherent dynamic balance to sustain appreciable inertia loading at high speeds. A relatively unknown mechanism is optimized for use as an acceleration-deceleration generator having a hesitation output. A relay transmission is suggested to shift the load from a constant to a variable speed drive at synchronous positions of zero acceleration.