Phase Switching Research Articles

Design of Transverse Brachiation Robot and Motion Control System for Locomotion between Ledges at Different Elevations.

Bio-inspired transverse brachiation robots mimic the movement of human climbers as they traverse along ledges on a vertical wall. The constraints on the locomotion of these robots differ considerably from those of conventional brachiation robots due primarily to the need for robust hand-eye coordination. This paper describes the development of a motion control strategy for a brachiation robot navigating between wall ledges positioned on a level plane or at different elevations. We based our robot on a four-link arm-body-tail system performing a four-phase movement, including a release phase, body reversal phase, swing-up phase, and grasping phase. We designed a gripper that uses passive wrist joint motion to grasp the ledge during the tail swing. We also developed a dynamic model by which to coordinate the swing-up movement, define the phase switching conditions, and time the grasping action of the grippers. In experiments, the robot proved highly effective in traversing between wall ledges of the same or different elevations.

Generation of Airy beams in Smith-Purcell radiation.

The metasurface has recently emerged as a powerful platform to engineer wave packets of free electron radiation at the mesoscale. Here, we propose that Airy beams can be generated when moving electrons interact with bianisotropic metasurfaces. By changing the intrinsic coupling strength, full amplitude coverage and 0-to-π phase switching of Smith-Purcell radiation can be realized from the meta-atoms. This unusual property shifts the wave front of the assembled Airy beam toward a parabolic trajectory. Experimental implementation displays that evanescent fields bounded at slotted waveguides can be coupled into Airy beams via Smith-Purcell radiation from a designed bianisotropic metasurface. Our method and design strategy offer an alternative route toward free-electron lasers with diffraction-free, self-accelerating, and self-healing beam properties.

P375 RECURRENT CEREBRAL ISCHEMIC ATTACKS IN PATIENT ON DIRECT ACTING ORAL ANTICOAGULANTS FOR ATRIAL FIBRILLATION

Abstract We present the case of an 81 year old man suffering from hypertensive heart disease with dilated evolution, dyslipidemia and previous TIAs; on one occasion documentation of cardioembolic origin of the event: AF paroxysm. CHA2DS2–VASc Score = 6. In therapy with DOAC: Dabigatran 110 mg x 2. Placed in therapy with Mysoline for inconstant tremors of the limbs and doubt of absences. Three days after the start of this therapy, the patient was hospitalized for dysarthria (2 h); NIHSS: 0 and ABCD2 score: 4; Brain CT: not acute lesions; centralization to Hub stroke not indicated and DOAC dosage not performed in the PS; at the verification of the DOAC concentration at the peak, during the infra–hospital intake, values of 123 ng / ml; no changes in blood pressure at onset, unchanged CHA2DS2 Vasc Score and HAS–BLED, unchanged blood tests, verified correct intake (CP count), kept the original packaging of the drug, there were no changes in body weight and there was no associated GE pathology; however, primidone was found to be a drug able to decreasing the plasma levels of Dabigatran as an inducer of P–gp glycoprotein. Tp confirmed with Dabigatran and Mysoline replaced with Clonazepam. Subsequent new hospitalization for dysarthria (2 h); centralized in Hub stroke; NIHSS: 1 (slight deviation of the buccal rim–outcome); pressure rise upon access to the PS; peak DOAC concentration 53 ng / ml; CT angiography of the neck and intracranial vessels with evidence of significant underlying vascular lesion load already in itself a contraindication to reperfusion tp which has been excluded; no brain CT lesions; hypothesized in the acute phase switch to another DOAC that has been performed; switch to Apixaban 5 mg 1 tablet x 2 and potentiation of antihypertensive treatment. NMR program of brain in sedation for claustrophobia. Subsequent new hospitalization for septic state and profound drowsiness; severe alteration of blood tests; subacute ischemic hypodensity in the peripheral territory of the left posterior brain; exitus of the patient. Many patients with AF remain at high residual risk of stroke despite an apparent appropriate dosage of oral anticoagulant drugs. However, a multidisciplinary and integrated investigation strategy of all known risk factors does not always give an effective answer, as in the case presented, and there is a lack of information in the literature regarding management options in such circumstances.

Ultrafast all-optical phase switching enabled by epsilon-near-zero materials in silicon.

Transparent conducting oxides (TCOs) have emerged as both particularly appealing epsilon-near-zero (ENZ) materials and remarkable candidates for the design and fabrication of active silicon nanophotonic devices. However, the leverage of TCO's ultrafast nonlinearities requires precise control of the intricate physical mechanisms that take place upon excitation. Here we investigate such behavior for ultrafast all-optical phase switching in hybrid TCO-silicon waveguides through numerical simulation. The model is driven from the framework of intraband-transition-induced optical nonlinearity. Transient evolution is studied with a phenomenological two-temperature model. Our results reveal the best compromise between energy consumption, insertion losses and phase change per unit length for enabling ultrafast switching times below 100 fs and compact active lengths in the order of several micrometers.

Fault Diagnosis Method of Six-Phase Permanent Magnet Synchronous Motor Based on Vector Space Decoupling

Compared with the three-phase motor, the six-phase motor has lower torque ripple and higher fault tolerance performance, which makes it widely used in aviation, ships, industrial manufacturing, and other application fields. However, the probability of failure of the polyphase motor system increases with the increase in the number of phases. In order to deal with the open phase fault and power switch fault of the six-phase inverter, a fault diagnosis method for the six-phase inverter based on vector space decoupling (VSD) is proposed. The open phase fault index is first determined according to the VSD decoupling inverse transform and the current constraints. The fault index is then optimized from the perspective of preventing misdiagnosis and improving reliability, and the open phase fault can be diagnosed in one fundamental cycle. In addition, the current trajectory of harmonic plane after switch fault is analyzed, and the back propagation (BP) neural network is used to identify the harmonic plane current trajectory of different types of switch fault. Finally, the correctness and feasibility of the proposed fault diagnosis method are verified by simulations and experiments. The obtained results demonstrate that the proposed method can quickly and accurately locate the open phase fault and switch fault without additional hardware. The proposed method is simple, efficient, and robust.

Hybrid Deep Learning Crystallographic Mapping of Polymorphic Phases in Polycrystalline Hf0.5 Zr0.5 O2 Thin Films.

By controlling the configuration of polymorphic phases in high-k Hf0.5 Zr0.5 O2 thin films, new functionalities such as persistent ferroelectricity at an extremely small scale can be exploited. To bolster the technological progress and fundamental understanding of phase stabilization (or transition) and switching behavior in the research area, efficient and reliable mapping of the crystal symmetry encompassing the whole scale of thin films is an urgent requisite. Atomic-scale observation with electron microscopy can provide decisive information for discriminating structures with similar symmetries. However, it often demands multiple/multiscale analysis for cross-validation with other techniques, such as X-ray diffraction, due to the limited range of observation. Herein, an efficient and automated methodology for large-scale mapping of the crystal symmetries in polycrystalline Hf0.5 Zr0.5 O2 thin films is developed using scanning probe-based diffraction and a hybrid deep convolutional neural network at a 2 nm2 resolution. The results for the doped hafnia films are fully proven to be compatible with atomic structures revealed by microscopy imaging, not requiring intensive human input for interpretation.

Viscoelastoplastic and incremental analysis of bridge with functional bearing

The functional bearing is one kind of the seismic isolation merging the advantages of the sliding system and the bearing system and it is widely used in Taiwan. To evaluate the performance of the functional bearing in a bridge effectively, a simple but accurate model is appreciated. The present paper attempts to model a bridge with functional bearing taking into account that the rate-dependent pier with hardening behavior. The proposed model is viscoelastoplastic and contains four phases including a viscoelastic-sticking, a viscoelastic-sliding, a viscoplastic-sticking, and a viscoplastic-sliding phase. The theoretical analysis in the state-space space enables us to obtain an exact solution for each phase. In order to simulate the exact behavior of the bridge system, the phase switching criteria with four conditions are derived and four computing modules for computations in four phases as well as four pull-back modules to direct toward to an exact module are developed. The four-phase model and the exact arrangement of computation qualitatively and quantitatively provide the exact duration of each phase and the proper indices for the plastic degradation of the pier as well as the consumption of the friction interface. One comparison between the simulation and the experimental result of a bridge’s shaking table test demonstrates the accuracy of the proposed model and its algorithm for the response of the bridge with functional bearing. Three numerical demonstrations show the performance of the proposed incremental analysis and the capability of the proposed model to distinguish the behavior of the bridge system under the near-fault and the far-fault earthquake. The duration of each of the four phases is accurately determined and the plastic degradation of the pier as well as the consumption of the friction interface are exactly evaluated. The difference of the behavior of the bridge system under the near-fault and the far-fault earthquake is qualitatively and quantitatively recognized.

Spatially-resolved relaxor to ferroelectric phase switching in 0.93Na1/2Bi1/2TiO3-0.07BaTiO3 ceramics

In situ, spatially-resolved synchrotron X-ray diffraction was utilized to investigate the electric field-induced heterogenous phase transformation of nonergodic relaxor 0.93Na1/2Bi1/2TiO3-0.07BaTiO3 ceramics. A Cu electrode was coated on one surface of a rectangular sample by aerosol deposition (AD), while a Pt layer was deposited on the opposite surface by sputter deposition. It is anticipated that a different stress state and/or domain morphology should occur on the AD deposited Cu electrode side due to the particle impact-consolidation deposition process. Under an electric field, different sample regions, i.e., AD, Middle, and Sputter sides, showed systematic changes in the relaxor to ferroelectric phase transition behavior. In particular, most <001> grains transformed at a sub-coercive field of 0.8 kV/mm, while the majority of the <111> grains only appeared to undergo transitions at a higher field (2.4 kV/mm). Also, the tetragonal phase became the dominant structure at higher field levels. Importantly, both <111> and <001> grains undergo phase switching at lower fields in the region close to the AD-processed layer. The study indicates that the AD process-induced stress can facilitate the electric field-induced relaxor to ferroelectric phase transition, i.e., the AD Cu side showed more significant lattice strain and domain texture than the sputter Pt side.

Physical separation of haplotypes in dikaryons allows benchmarking of phasing accuracy in Nanopore and HiFi assemblies with Hi-C data

BackgroundMost animals and plants have more than one set of chromosomes and package these haplotypes into a single nucleus within each cell. In contrast, many fungal species carry multiple haploid nuclei per cell. Rust fungi are such species with two nuclei (karyons) that contain a full set of haploid chromosomes each. The physical separation of haplotypes in dikaryons means that, unlike in diploids, Hi-C chromatin contacts between haplotypes are false-positive signals.ResultsWe generate the first chromosome-scale, fully-phased assembly for the dikaryotic leaf rust fungus Puccinia triticina and compare Nanopore MinION and PacBio HiFi sequence-based assemblies. We show that false-positive Hi-C contacts between haplotypes are predominantly caused by phase switches rather than by collapsed regions or Hi-C read mis-mappings. We introduce a method for phasing of dikaryotic genomes into the two haplotypes using Hi-C contact graphs, including a phase switch correction step. In the HiFi assembly, relatively few phase switches occur, and these are predominantly located at haplotig boundaries and can be readily corrected. In contrast, phase switches are widespread throughout the Nanopore assembly. We show that haploid genome read coverage of 30–40 times using HiFi sequencing is required for phasing of the leaf rust genome, with 0.7% heterozygosity, and that HiFi sequencing resolves genomic regions with low heterozygosity that are otherwise collapsed in the Nanopore assembly.ConclusionsThis first Hi-C based phasing pipeline for dikaryons and comparison of long-read sequencing technologies will inform future genome assembly and haplotype phasing projects in other non-haploid organisms.

Effect of the phase switching of the optical FID in magnetic field

This work demonstrates the possibility of switching the phase of optical free induction decay (FID) in time-domain experiments. This possibility arises in experiments with paramagnetic molecules (free radicals) in a magnetic field. Changing the direction of the magnetic field alters the direction of rotation of the FID polarization plane and inverts the phase of one of the components of FID. This effect will be useful for heterodyne detection of the optical FID of the free radicals in the terahertz region.

Kid-size robot humanoid walking with heel-contact and toe-off motion.

Human-like features, like toe-off, heel-strike can enhance the performance of bipedal robots. However, few studies have considered the anthropomorphism of walking planning. Fewer studies have achieved their toe-off, heel-strike gait planning framework in a child-sized humanoid robot platform. This paper presents a human-like walking control framework based on the Divergent Component of Motion (DCM) com planning method that enables a child-sized humanoid robot to walk with a humanoid pattern with a speed of 0.6 s per step a strike of 30 cm. The control framework consists of three parts: the human-like gait generation of the center of mass (CoM) and swings foot trajectory, the dynamic replan in phase switch and the upper body stabilization controller. The dynamic replanning of the CoM and foot trajectory can efficiently decrease the vibration in the step-phase switch. The up-body stabilization controller can reduce the up-body swing in walking and increase the robot's stability while walking. The robot uses a mems-based inertial measurement unit (IMU) and joint position encoders to estimate the current state of the robot and use force-sensitive resistors (FSR) on the robot foot to identify the actual step phase of the robot. None of these solutions is high-cost or difficult to integrate with a child-size robot. Software simulations and walking experiments are using to verify the motion control algorithm. The effectiveness of the pattern generation and the controller can realize more human-like walking styles in a child-size robot are confirmed.

A 0.3-to-1-GHz IoT Transmitter Employing Pseudo-Randomized Phase Switching Modulator and Single-Supply Class-G Harmonic Rejection PA

A wideband Internet of Things (IoT) transmitter (TX) employing open-loop binary frequency-shift keying (BFSK) modulator with a pseudo-randomized phase transition (PRPT) time and a single-supply Class-G harmonic rejection (HR) power amplifier (PA) is presented. The proposed open-loop phase switching modulator eliminates the data-rate limitation in a conventional phase-locked loop (PLL)-based closed-loop modulator, while the PRPT scheme increases the effective phase resolution with a better power efficiency than delta–sigma modulation (DSM)-based randomization. Thus, a low spur level below −40 dBc is achieved with only a 4-bit phase resolution. The Class-G HR PA, including a four-level supply voltage waveform generator, is proposed as a high-efficiency and low spurious PA architecture. The proposed HR PA presents the third- and fifth-harmonics cancellation over the 0.3-to-1-GHz band, while only a single supply is required for Class-G implementation of the HR PA. The proposed BFSK TX is implemented in a 55-nm CMOS process. Measured with a 0.3-to-1-GHz continuous-wave carrier, TX output power and PA drain efficiency are 2.7 ± 0.2 dB and 52% ± 3%, respectively, operating from a 0.9-V supply. The HRs of −31.4/−42.7 and −28.2/−42.4 dBc at the third/fifth harmonics are measured at the lowest (0.3 GHz) and the highest (1 GHz) carrier frequencies, respectively. With a data rate of 1 Mb/s, the measured FSK errors are 3.6% and 4.2% at both ends of the operating frequency.

Magnetic Generation and Switching of Topological Quantum Phases in a Trivial Semimetal α−EuP3

Topological materials have drawn increasing attention owing to their rich quantum properties, as highlighted by a large intrinsic anomalous Hall effect (AHE) in Weyl and nodal-line semimetals. However, the practical applications for topological electronics have been hampered by the difficulty in the external control of the band topology. Here we demonstrate a magnetic-field-induced switching of band topology in $\alpha{\mathrm{-EuP}}_3$, a magnetic semimetal with a layered crystal structure derived from black phosphorus. When the magnetic field is applied perpendicular to the single mirror plane of the monoclinic structure, a giant AHE signal abruptly emerges at a certain threshold magnetization value, giving rise to a prominently large anomalous Hall angle of $\left|\Theta_{\mathrm{AHE}}\right| \sim 20^{\circ}$. When the magnetic field is applied along the inter-layer direction, which breaks the mirror symmetry, the system shows a pronounced negative longitudinal magnetoresistance. On the basis of electronic structure calculations and symmetry considerations, these anomalous magneto-transport properties can be considered as manifestations of two distinct topological phases: topological nodal-line and Weyl semimetals, respectively. Notably, the nodal-line structure is composed of bands with the same spin character and spans a wide energy range around the Fermi level. These topological phases are stabilized via the exchange coupling between localized Eu-4$f$ moments and mobile carriers conducting through the phosphorus layers. Our findings provide a realistic solution for external manipulation of band topology, enriching the functional aspects of topological materials.

Brain Neural Activity Patterns in an Animal Model of Antidepressant-Induced Manic Episodes.

Background: In the treatment of patients with bipolar disorder (BP), antidepressant-induced mania is usually observed. The rate of phase switching (from depressive to manic) in these patients exceeds 22%. The exploration of brain activity patterns during an antidepressant-induced manic phase may aid the development of strategies to reduce the phase-switching rate. The use of a murine model to explore brain activity patterns in depressive and manic phases can help us to understandthe pathological features of BP. The novel object recognition preference ratio is used to assess cognitive ability in such models.Objective: To investigate brain Ca2+ activity and behavioral expression in the depressive and manic phases in the same murine model, to aid understanding of brain activity patterns in phase switching in BP.Methods: In vivo two-photon imaging was used to observe brain activity alterations in a murine model in which induce depressive-like and manic-like behaviors were induced sequentially. The immobility time was used to assess depressive-like symptoms and the total distance traveled was used to assess manic-like symptoms.Results: In vivo two-photon imaging revealed significantly reduced brain Ca2+ activity in temporal cortex pyramidal neurons in the depressive phase in mice exposed to chronic unpredictable mild stress compared with naïve controls. The brain Ca2+ activity correlated negatively with the novel object recognition preference ratio within the immobility time. Significantly increased brain Ca2+ activity was observed in the ketamine-induced manic phase. However, this activity did not correlate with the total distance traveled. The novel object recognition preference ratio correlated negatively with the total distance traveled in the manic phase.

Dynamic FMR1 granule phase switch instructed by m6A modification contributes to maternal RNA decay

Maternal RNA degradation is critical for embryogenesis and is tightly controlled by maternal RNA-binding proteins. Fragile X mental-retardation protein (FMR1) binds target mRNAs to form ribonucleoprotein (RNP) complexes/granules that control various biological processes, including early embryogenesis. However, how FMR1 recognizes target mRNAs and how FMR1-RNP granule assembly/disassembly regulates FMR1-associated mRNAs remain elusive. Here we show that Drosophila FMR1 preferentially binds mRNAs containing m6A-marked “AGACU” motif with high affinity to contributes to maternal RNA degradation. The high-affinity binding largely depends on a hydrophobic network within FMR1 KH2 domain. Importantly, this binding greatly induces FMR1 granule condensation to efficiently recruit unmodified mRNAs. The degradation of maternal mRNAs then causes granule de-condensation, allowing normal embryogenesis. Our findings reveal that sequence-specific mRNAs instruct FMR1-RNP granules to undergo a dynamic phase-switch, thus contributes to maternal mRNA decay. This mechanism may represent a general principle that regulated RNP-granules control RNA processing and normal development.

Thermal dynamics of phase switching process of an SOI rib waveguide covered with a Ge2Sb2Te5 phase change material film

The combination of phase-change materials (PCMs) and integrated photonics promotes the development of new forms of all-optical devices and potentially provides large-scale all-optical arithmetic-logic units and neuromorphic processing chips using the large contrast in optical properties when switched between amorphous and crystalline phase states. Therefore, a proper understanding of the refractive index fluctuations during phase-switching is essential for controlled and optimized device operation. We present analytical results to simulate the temperature-field distribution while an optical pulse is injected into a waveguide with a phase change material cell. These results demonstrate good agreement with the calculations by the finite element method. Furthermore, the crystallization fraction and refractive index change of the Ge2Sb2Te5 PCM cell are investigated in calculation, along with the attenuation effect of the SOI rib waveguide during the phase switching and the dependence on the optical injection. Therefore, it is necessary to set the optical pulses appropriately for the phase-switching process for particular devices, such as optical memory and photonics neurons.

Highly Efficient Single-Stage DAB Microinverter Using a Novel Modulation Strategy to Minimize Reactive Power

This article proposes a highly efficient single-stage dual-active-bridge (DAB) microinverter with a novel modulation strategy to minimize the reactive power flow of DAB converter. Using the proposed modulation, the DAB microinverter achieves good controllability and high efficiency with the following features. First, the variable-frequency control algorithm linearizes the nonlinear function of the phase shift angle, enabling a simple closed-loop control for the sinusoidal trajectory tracking. Second, the proposed modulation strategy minimizes the reactive power flow during the switching period while guaranteeing the zero-voltage-switching (ZVS) turn-on of all switches. With minimized reactive power, current stress and power losses are significantly reduced. Thus, the DAB microinverter achieves a maximum efficiency of 96.87%. Third, the proposed phase shift angles and switching frequency are obtained in an analytic form, thereby that they are computationally simple and easy to implement. The operation principle of the proposed modulation strategy is theoretically analyzed and verified. Experimental results based on a 330-W prototype module are conducted to evaluate the performance of the proposed inverter and to verify the analysis.

Frequency spectra based approach to analytical formulation and minimization of voltage THD in staircase modulated multilevel inverters

Staircase Modulation (SCM) is a popular switching strategy for multilevel inverters (MLI), which is often a preferable alternative to Pulse Width Modulation (PWM) due to its reduced switching losses, especially for MLIs with a relatively high number of voltage levels (N). In some applications, such as motor drives, or when output filters are applicable, SCM may also suit MLIs with moderate N values. While MLIs with Equal DC Sources (EDCS) are more common, MLIs with Unequal DC Sources (UDCS), such as asymmetric Cascaded H-Bridge (CHB) MLIs are known to further reduce the waveforms’ Total Harmonic Distortion (THD). The main objective of SCM is to adjust the waveform’s fundamental component, while employing some harmonic mitigation strategy, such as THD minimization. Such an optimization approach relies on an accurate THD formulation, which eliminates underestimation errors associated with numerical THD approximations. This paper reveals novel generic analytical formulations of both Phase-voltage THD (PTHD) for single-phase MLIs and Line-voltage THD (LTHD) for three-phase MLIs. The revealed exact formulation approach is derived from Fourier series representation of THD, resulting in simple closed-form PTHD and LTHD expressions, applicable to any MLI topology, with either EDCS or UDCS configurations, and arbitrary value of N (odd and even). Given an arbitrary N value, the proposed formulations can be used to generate symbolic N-level PTHD or LTHD expressions, which are symbolic functions of the Phase Switching Angles (PSA) and (optionally) the DC source Ratios (DCR). The revealed THD formulations are verified and compared against recently introduced time-domain-based THD formulations. It is shown that when both time and frequency-based formulations are employed in THD minimizations to form a novel Hybrid Temporal-Spectral (HTS) Optimal Minimization of THD (OMTHD) approach, even better results can be achieved. The novel OMTHD is deeply explored and verified by both digital simulations and Controller + Hardware in Loop (C-HIL) based real-time experiments using 7- and 8-level three-phase MLI configurations. A downloadable supplemental file containing Maple and MATLAB functions of the proposed THD expressions, as well as pre-calculated sets of optimum variables for different values of N is provided for readers' convenience.

Analytical Expression for Line Voltage THD of Three-Phase Staircase Modulated Multilevel Inverters

In this article, a simple closed-form analytical expression for the line-voltage total harmonic distortion (LTHD) of three-phase staircase-modulated (SCM) multilevel inverters (MLI) is proposed. The revealed expression is valid for any conventional MLI topology with arbitrary number and parity of voltage levels. The proposed formulation is presented as an analytic function of the number of voltage levels (N) and the phase switching angles (PSA); thus, it is suited to MLIs of equal voltage source supply and of any topology. This function may be employed for accurate LTHD calculation and optimization. The results are verified against LTHD calculations and optimizations, obtained numerically from previous works. Both processor in loop (PIL)- and controller + hardware in loop (C-HIL)-based real-time experimental validations are included as well. A downloadable file containing the Maple and MATLAB functions of the proposed expression are also provided.

Unconventional Hysteretic Transition in a Charge Density Wave.

Hysteresis underlies a large number of phase transitions in solids, giving rise to exotic metastable states that are otherwise inaccessible. Here, we report an unconventional hysteretic transition in a quasi-2D material, EuTe_{4}. By combining transport, photoemission, diffraction, and x-ray absorption measurements, we observe that the hysteresis loop has a temperature width of more than 400K, setting a record among crystalline solids. The transition has an origin distinct from known mechanisms, lying entirely within the incommensurate charge density wave (CDW) phase of EuTe_{4} with no change in the CDW modulation periodicity. We interpret the hysteresis as an unusual switching of the relative CDW phases in different layers, a phenomenon unique to quasi-2D compounds that is not present in either purely 2D or strongly coupled 3D systems. Our findings challenge the established theories on metastable states in density wave systems, pushing the boundary of understanding hysteretic transitions in a broken-symmetry state.