Phase Shift Features Research Articles

A need for speed: Objectively identifying full-body kinematic and neuromuscular features associated with faster sprint velocities.

Sprinting is multifactorial and dependent on a variety of kinematic, kinetic, and neuromuscular features. A key objective in sprinting is covering a set amount of distance in the shortest amount of time. To achieve this, sprinters are required to coordinate their entire body to achieve a fast sprint velocity. This suggests that a whole-body kinematic and neuromuscular coordinative strategy exists which is associated with improved sprint performance. The purpose of this study was to leverage inertial measurement units (IMUs) and wireless surface electromyography (sEMG) to find coordinative strategies associated with peak over-ground sprint velocity using machine learning. We recruited 40 healthy university age sprint-based athletes from a variety of athletic backgrounds. IMU and sEMG data were used as inputs into a principal components analysis (PCA) to observe major modes of variation (i.e., PC scores). PC scores were then used as inputs into a stepwise multivariate linear regression model to derive associations of each mode of variation with peak sprint velocity. Both the kinematic (R 2 = 0.795) and sEMG data (R 2 = 0.586) produced significant multivariate linear regression models. The PCs that were selected as inputs into the multivariate linear regression model were reconstructed using multi-component reconstruction to produce a representation of the whole-body movement pattern and changes in the sEMG waveform associated with faster sprint velocities. The findings of this work suggest that distinct features are associated with faster sprint velocity. These include the timing of the contralateral arm and leg swing, stance leg kinematics, dynamic trunk extension at toe-off, asymmetry between the right and left swing side leg and a phase shift feature of the posterior chain musculature. These results demonstrate the utility of data-driven frameworks in identifying different coordinative features that are associated with a movement outcome. Using our framework, coaches and biomechanists can make decisions based on objective movement information, which can ultimately improve an athlete's performance.

Moisture measurement of tea leaves during withering using multifrequency microwave signals optimized by ant colony optimization

The rapid and accurate moisture content (MC) measuring of withering tea leaves faces multiple challenges. In this study, a self-developed microwave sensing system equipped with multifrequency-swept signals (2.00–10.00 GHz, an interval of 10.00 MHz) was used to measure the MC of withering tea leaves (16.25%–77.65%). Four kinds of hybrid-based ant colony optimizations were advanced to optimize microwave frequency signals, and the attenuation features at six frequencies (2.16, 3.42, 3.88, 4.48, 5.32 and 7.70 GHz) and phase shift features at four frequencies (2.84, 4.04, 7.88 and 8.43 GHz) were selected. Based on those optimized features, three primary models (support vector regression, extreme gradient boosting, and multi-layer perception) and one secondary model (decision tree) presented the best MC values (the average of mean absolute error was 0.349). The results showed the potential application of microwave technology in the MC monitoring in tea processing industry. • A microwave sensing system was developed for moisture detection in tea withering. • A hybrid-based ACO algorithm was designed to optimize the frequency features. • Attenuation and phase shift features correlated with MC were selected by MRACO. • The best MC detection was achieved by the stacking model of SVR, LGBM, and MLP.

A phase-gradient acoustic metasurface for broadband duct noise attenuation in the presence of flow

A phase-gradient acoustic metasurface is designed based on wavefront manipulation for achieving broadband noise reduction in a flow duct. It is constructed by eight periodically arranged varying-depth units filled with porous materials, forming a linear phase shift of reflected wave from 0 to 2π at 3000Hz. The linear reflected phase-shifting can be roughly maintained in a wide frequency range. By employing the broadband phase-shift feature of the units, the metasurface exhibits an enhanced sound absorption performance in terms of the absorption coefficient and bandwidth when comparing to the individual units, which originates from forcing the higher-order modes of reflection waves to be evanescent. Then, its transmission attenuation characteristics in the presence of background flow are assessed by installing it on the side wall of a flow tube. The effects of flow speed (Mach number is up to 0.3) and sound source position (at the upstream and downstream sides of the metasurface) are experimentally and numerically investigated. Results show that the attenuation performance of the metasurface decreases with flow speed for the upstream sound source while increasing for the downstream sound source. For both upstream and downstream sound sources, a high transmission loss (≥20dB) is achieved by the metasurface in the frequency range of 1500–3000Hz at different flow speeds. Hence, the proposed metasurface is promising for achieving broadband noise attenuation in the presence of flow.

Implementation of Installation Two-way DC-DC Converter with IoT Control and Monitoring

Renewable energy generation, such as solar energy, produces electrical energy with fluctuating voltages. Light intensity is one of the causes of this fluctuating voltage. The resulting voltage is directly proportional to the intensity of the light. It is necessary to implement a converter system to increase efficiency in the solar panel system. The converter with an insert buck-boost topology is designed to regulate the direction of power in and out of the battery. Setting the direction of the flow of power is considered important in order to increase the efficiency of the solar panel system. This research focuses on the design and implementation of the Online Insertion TwoWay DC-DC Converter. The converter functions to connect the storage media and the DC Bus and smoothes the output current with a phase shift of the PWM signal by 180°. The phase shift feature is set using the ATMEGA328P minimum system. In addition to functioning as a buck (charging) and boost (discharging) battery, there is also an online monitoring function. The online monitoring feature is designed to display the DC Bus voltage value and battery voltage, while the online controlling feature allows users to manually change the converter mode from buck to boost or vice versa. The test results show that the Insertion Bidirectional DC-DC Converter can produce a stable voltage according to the given duty cycle. The average efficiency is 88% for buck mode and 92% for boost mode. In the blynk application, it can display the DC Bus voltage and battery voltage and the user can change the converter mode manually.

РОЗРОБЛЕННЯ СПЕЦІАЛЬНИХ МАТЕМАТИЧНИХ МОДЕЛЕЙ ДОСЛІДЖЕННЯ ТОЧНОСТІ РЕАЛЬНИХ ПОВЕРХОНЬ ЗУБЧАСТИХ КОЛІС ЦИКЛОЇДАЛЬНИХ ПЕРЕДАЧ

Promising areas for improving robotic systems based on cycloidal gears aimedto increase their accuracy and other performance characteristics. The accuracy of the rotary unit and the mechanism as a whole is determined by errors in the manufacture of the transmission. Integral quantities are not enough to assess the accuracy of the transmission wheels. To determine the errors of the geometry of parts requires a technique that includes modeling of its real surface. The cyclic nature of the curve that defines the generating surface of the wheel allows the use of optimized mathematical models based on Fourier series. The technique allows for accurate processing of experimentaldata and compare them with the theoretical profile. Approbation of the concept requires modeling of the theoretical profile and research of the manufactured parts. The method allows to determine the parameters of the wheels by analyzing the differences between the simulated surface of the part and the theoretical profile. A hole in the part can be used as a base surface in the manufacture. Determination of the surface profile of the transmission wheel is carried out on a coordinate measuring machine, which allows to get a set of points. Surface modeling by discrete values is performed by spline interpolation. In the future, the description of the surface is performed using harmonic functions. The proposed mathematical apparatus allows the use of spectral analysis tools and statistical methods. The harmonic series is obtained by means of the Fourier transform. Monte Carlo methods allow to compare the mathematical model of the real profile of the mechanical transmission wheel and the theoretical surface. This makes it possible to take into account the presence of eccentricity, phase shift and other features of the part when determining the accuracy parameters. The mathematical model allows to effectively use experimental data in determining the characteristics of the surface of the part. The use of stochastic parameters in modeling makes it possible to take into account the accuracy of the wheel and increase the accuracy of determining the parameters of mechanical transmission.

Automatic detection and characterization of quantitative phase images of thalassemic red blood cells using a mask region-based convolutional neural network.

.Significance: Label-free quantitative phase imaging is a promising technique for the automatic detection of abnormal red blood cells (RBCs) in real time. Although deep-learning techniques can accurately detect abnormal RBCs from quantitative phase images efficiently, their applications in diagnostic testing are limited by the lack of transparency. More interpretable results such as morphological and biochemical characteristics of individual RBCs are highly desirable.Aim: An end-to-end deep-learning model was developed to efficiently discriminate thalassemic RBCs (tRBCs) from healthy RBCs (hRBCs) in quantitative phase images and segment RBCs for single-cell characterization.Approach: Two-dimensional quantitative phase images of hRBCs and tRBCs were acquired using digital holographic microscopy. A mask region-based convolutional neural network (Mask R-CNN) model was trained to discriminate tRBCs and segment individual RBCs. Characterization of tRBCs was achieved utilizing SHapley Additive exPlanation analysis and canonical correlation analysis on automatically segmented RBC phase images.Results: The implemented model achieved 97.8% accuracy in detecting tRBCs. Phase-shift statistics showed the highest influence on the correct classification of tRBCs. Associations between the phase-shift features and three-dimensional morphological features were revealed.Conclusions: The implemented Mask R-CNN model accurately identified tRBCs and segmented RBCs to provide single-RBC characterization, which has the potential to aid clinical decision-making.

Envelope Phase Shift Feature Extraction of Underwater Target Echo

Aiming at the problem of target classification with different physical property parameters, the phase characteristics of echo envelope associated with different physical property parameters are studied, and the feature extraction method of the phase shift characteristics of the target echo envelope is established. The extraction method and the feature resolution performance of the phase shift characteristics of echo envelope are verified by the water-tank test of cylindrical targets with different materials and finite length. The experimental results of the underwater cylindrical target echo show that the feature of target echo envelope phase shift has significant difference with the change of target material, structure and radial scale. The phase shift feature of underwater target echo envelope has good performance for targets with different physical property parameters.

Pedal to the Metal: Velocity and Power in High-Level Golfers.

Parker, J, and Lundgren, LE. Pedal to the metal: Velocity and power in high-level golfers. J Strength Cond Res 35(12): 3425-3431, 2021-In most rotational power assessments, discrete variables are used for subsequent examination; however, movements are continuous, and data can be collected in time series. The purpose of this investigation was to examine the velocity- and power-time series characteristics of a standing rotation test and identify relationships with golf performance. Thirty-one golfers performed a golf-specific rotation test (GSRT) with 3 different resistances (6, 10, and 14 kg) in a robotic engine system. Time series of velocity and power was calculated from the raw data, and each repetition was then normalized to 0-100%. Principal component analyses (PCAs) were performed on velocity and power waveforms. The PCA used an eigenvalue analysis of the data covariance matrix. The relationship between clubhead speed (CHS) and all principal components (PC) was examined using linear regression. Ten velocity parameters and 6 power parameters explained 80% of the variance in the data. For velocity, the first 2 PCs identified both magnitude and phase shift features while PCs 3-5 identified difference features. For power, the first 2 PCs identified both magnitude and phase shift features, the third PC identified a phase shift feature, and the fourth PC identified a difference feature. The highest relationship with CHS was shown for GSRT with 14 kg in PC2 for power (R2 = 0.48, p < 0.001). The PCA of the GSRT power test could distinguish intraindividual differences, external loads, and sex-based differences. Athletes should focus on accelerating smoothly through the movement, particularly with heavier loads, and not pulling aggressively at the beginning of the rotational movement to achieve maximum power.

Surfing the Waves of the CMJ; Are There between-Sport Differences in the Waveform Data?

The ability to analyse countermovement jump (CMJ) waveform data using statistical methods, like principal component analysis, can provide additional information regarding the different phases of the CMJ, compared to jump height or peak power alone. The aim of this study was to investigate the between-sport force-time curve differences in the CMJ. Eighteen high level golfers (male = 10, female = 8) and eighteen high level surfers (male = 10, female = 8) performed three separate countermovement jumps on a force platform. Time series of data from the force platform was normalized to body weight and each repetition was then normalized to 0–100 percent. Principal component analyses (PCA) were performed on force waveforms and the first six PCs explained 35% of the variance in force parameters. The main features of the movement cycles were characterized by magnitude (PC1 and PC5), waveform (PC2 and PC4), and phase shift features (PC3). Surf athletes differ in their CMJ technique and show a greater negative centre of mass displacement when compared to golfers (PC1), although these differences are not necessarily associated with greater jump height. Principal component 5 demonstrated the largest correlation with jump height (R2 = 0.52). Further studies are recommended in this area, to reveal which features of the CMJ that relate to jumping performance, and sport specific adaptations.

Optical bistability in a single-sided cavity coupled to a quantum channel

In this paper, we discuss the long wavelength optical reflection and bistable behavior of an InGaN/GaN quantum dot nanostructure coupled to a single-sided cavity. It is found that due to the presence of a strong coupling field, the reflection coefficient can be controlled at long wavelength, which is essential for adjusting the threshold of reflected optical bistability. Moreover, the phase shift features of the reflection pulse inside an electromagnetically induced transparency window are also discussed.

Simple Baseband Method for the Distributed Analysis of Brillouin Phase-Shift Spectra

The phase shift feature of stimulated Brillouin scattering is rarely used for the development of sensors based on the Brillouin optical time-domain analysis (BOTDA). However, this feature shows significant interest for sensing thanks to its linear dependence around the Brillouin frequency shift. Until now, distributed Brillouin phase shift (BPS) measurements required complex modulations, high-bandwidth detection, and sharp filtering. Recently, we introduced the possibility of developing simple distributed measurements of BPS in BOTDA using the baseband technology. The basic idea was the use of a Sagnac interferometer coupled to a conventional BOTDA without filtering and incorporating balanced detection. Although the concept was demonstrated, the setup proposed (using a 2 $\times $ 2 optical coupler) had significant shortcomings, the main one being its lack of stability due to the need of setting the interferometer bias through the polarization of the interacting waves. This restricted severely the practicality of the method. In this letter, we propose a setup with enhanced stability thanks to the use of a $3\times 3$ optical coupler. With this configuration, the impact of the drifts along the measurement is strongly reduced, and the quality of the measurements improves substantially. The method is theoretically studied and demonstrated experimentally.

Optical pulse shaper with integrated slab waveguide for arbitrary waveform generation using optical gradient force

Integrated optical pulse shaper opens up possibilities for realizing the ultra high-speed and ultra wide-band linear signal processing with compact size and low power consumption. We propose a silicon monolithic integrated optical pulse shaper using optical gradient force, which is based on the eight-path finite impulse response. A cantilever structure is fabricated in one arm of the Mach—Zehnder interferometer (MZI) to act as an amplitude modulator. The phase shift feature of waveguide is analyzed with the optical pump power, and five typical waveforms are demonstrated with the manipulation of optical force. Unlike other pulse shaper schemes based on thermo—optic effect or electro—optic effect, our scheme is based on a new degree of freedom manipulation, i.e., optical force, so no microelectrodes are required on the silicon chip, which can reduce the complexity of fabrication. Besides, the chip structure is suitable for commercial silicon on an insulator (SOI) wafer, which has a top silicon layer of about 220 nm in thickness.

Research on Complex Channel Characteristic for Hypersonic Vehicles

Hypersonic vehicles experience complex and bad communication environment including high dynamic Doppler and unique plasma sheath. Characteristics of the complex channel environment, which is divided into two distinguished channel part, will be discussed. The atmospheric propagation part of the complex channel is modeled as frequency-selective fast fading channel based on analysis of its coherence time and coherence bandwidth. The plasma sheath channel transmission (attenuation) and phase shift characteristics when radio wave pass through it is obtained by the scatter matrix method and FDTD algorithm. Finally a typical blunt conical hypersonic vehicle model is simulated to evaluate plasma sheath channel transmission and phase shift features, results show that communications might completely interrupted under high speed above 16 Mach because of small transmission coefficient and large phase shift.

SUB-100 nm LITHOGRAPHY WITH PATTERN AND PARTIAL COHERENCE CONTROL

This paper describes optical patterning of sub-lithographic wavelength features using only conventional chrome-on-glass binary photomasks without phase-shift features. The sub-100 nm patterns were obtained through manipulation of masks bias designs and partial coherence control of the lithographic radiation. The key factors in the design of experiments are the density and design of masks patterns and the partial coherence of exposure radiation system used. Based on the study, smallest resolution of 36% that of designed value can be obtained for features of 75 nm using a 200 nm designed line width. Besides indication of proposed process' resolution limits for further applications, advantages of the method allows its application to applications requiring sub-100 nm critical dimensions through use of biased pattern designs, especially feasible in devices such as deep sub-micrometer comb drives actuators in nano-microelectromechanical structures; metal–semiconductor–metal photodetectors, and nanophotonic crystal structures, etc.

Synthesized processing techniques for monolithic integration of nanometer-scale hole type photonic band gap crystal with micrometer-scale microelectromechanical structures

This article reports the synthesized fabrication process design and module development that enabled the monolithic integration of deep submicrometer size, two dimensional hole-type photonic band gap crystals (PhCs) with microelectromechanical system (MEMS) actuators and optical testing structures (OTS). Techniques enabling sublithographic wavelength patterning using only conventional chrome-on-glass binary photomasks without phase shift features were achieved through the manipulation of mask bias designs and the partial coherence control of the lithographic exposure system. Together with the development of time multiplexed reactive ion etching and focus ion beam milling techniques, such design of the process allows the realization of highly dense PhC and MEMS actuators physically released from the buried oxide layer. Here, disparate pattern dimensions [with PhC critical dimensions (CDs) of only 175nm, MEMS typical dimensions of 2μm, and OTS openings more than 400μm wide], varied etch depth (3μm for the PhC and MEMS, 61μm for the OTS), and the requirement of a sufficient process latitude for exposure and etch processes are some of the key challenges that were overcome for a successful integration of air-bridge-type PhC CDs with movable MEMS actuators. Hence, the works described in this article enable MEMS tunable PhC properties with potential application in next generation dynamic optical communication networks and photonic integrated circuits.

DEEP UV LITHOGRAPHY FOR PILLAR TYPE NANOPHOTONIC CRYSTAL

The progress made to resolve challenges met in using deep UV lithography for batch fabrication of pillar type nano-photonic crystals is described, using data from experiments carried out based on two degrees, full factorial design of experiments and subsequently processed using variance analysis. A binary mask without phase shift features was used to obtain information on effects of lithographic parameters such as antireflection coatings, resist preparation recipes, exposure latitude and depth of focus biases. The results derived hence enabled successful derivations of high quality arrays of dense nano-pillars.

Nonuniform DFB-SOAs: dynamic Characteristics of bistability and a novel configuration based on linearly variable current injection

Starting from the coupled-mode equation and carrier rate equation, this paper has analyzed numerically the bistable dynamic characteristics of phased-shifted and chirped distributed-feedback semiconductor optical amplifiers (DFB-SOAs). The results show that phase shift first worsens the shape distortion of the falling edge of the output pulse and then alleviates it with the decreased initial detuning. This tendency can be suppressed by introducing chirp. We also proposed a novel configuration based on linearly variable current injection, which not only enhances the on-off switching ratio, but also has a similar transmission spectrum with phase-shift effects and similar bistable features, such as the wide frequency band and the flat upper branch of the hysteresis, with chirp effects.

Probing the Subsurface Structure of Active Regions with the Phase Information in Acoustic Imaging

We present the phase information of solar p-mode waves constructed with an acoustic imaging technique in the solar interior. There exists a phase shift between the time series constructed with ingoing waves and outgoing waves. We find that this phase shift is different in an active region and the quiet Sun. The p-mode travel time is shorter in the magnetic regions than in the quiet Sun. We construct a three-dimensional phase shift map of the solar interior. As with the acoustic absorption images, the phase shift features of the active region in maps at the surface correlate with magnetic fields. The vertical extension of phase shift features in the active region is smaller in the phase maps constructed with shorter wavelengths. This indicates the vertical spatial resolution of these three-dimensional phase maps is sensitive to the range of modes used in constructing the signal. The actual depths of the phase shift features in the active region may be smaller than those shown in the three-dimensional phase maps.

Computer-aided phase shift mask design with reduced complexity

We propose a new approach to systematic phase shift mask design. In doing so, we constrain the complexity of the mask at a pre-specified level by limiting the number of on the mask. We then optimize the location, size and phase of the features so as to achieve a desired intensity pattern on the wafer. The main advantage of this object-based approach over our previous pixel-based solution is that it results in substantially larger assisting phase shift features, and is therefore easier to fabricate. Our approach can also be used to design masks with proper bias and/or extension of the depth of focus. We show examples of contact hole, bright line and chromeless line-space mask designs. Finally, we show experimental results using the new approach.