Sinusoidally Research Articles

An experimental parametric study assessing the effect of a certain initial geometric imperfection on cylinder buckling

Given the sensitivity of axially-loaded cylinder buckling to geometric imperfections, the advent of additive manufacturing provides a compelling platform to assess subtle changes in initial configuration from an experimental perspective. The cylindrical form is ubiquitous in many load-bearing contexts, from soda cans to submarines to rocket fuel tanks. Despite the relative simplicity of the shape, it is striking how the assessment of buckling loads continues to pose strong challenges to the designers of these load-bearing components, often in a situation where weight-saving is a key constraint. Furthermore, this type of buckling typically corresponds to a sudden, severe, catastrophic event, and in addition to posing serious consequences in practice, this also presents challenges for those conducting high-fidelity experiments, especially in terms of repeatability. Any conditions that deviate from a pristine cylindrical shape, and purely axial loading, are the root-cause of the buckling variability. Typically, the slight deviations from the pristine (perfect) conditions are somewhat random and unpredictable in nature. 3D-printing now provides the experimentalist with the ability to produce cylindrical specimens to a very high degree of geometric fidelity, thus allowing a degree of control of the form of subtle geometric imperfections. This paper focuses attention on a specific form of deviation from a pristine cylindrical shape, in which the longitudinal sides follow a mild cosine wave form. The amplitude of this shape is varied (in both directions, i.e., inwards and outwards), and its effect on both the buckling load and buckling mode shape assessed experimentally, using the outcome of finite element analysis as a guide.

Mathematical model for applying electromagnetic (EM) on a Carreau fluid in a tube: Stimulation to avoid sediment accumulation in oil tanks

AbstractThe purpose of this article is to study the effect of electromagnetic (EM) stimulation on the pipeline, which has an electrical and thermal effect in addition to the chemical reaction on the crude oil and makes a sinusoidal wave on the wall. Modeling the crude oil as Carreau fluid is done. EM stimulation is an effective and safe technology that can be used to improve fluid movement in a variety of industrial applications. The flow analysis by applying EM may avoid blocking the crude oil pipeline which leads to a loss of production and capital investment. The basic partial differential equations of momentum, temperature and concentration are reduced to a system of nonlinear partial differential equations, which is solved numerically by using the Rung–Kutta–Merson method with Newton iteration in a shooting and matching technique under the assumption of long wavelength and the effect of physical implanted parameters is represented through charts for velocity, temperature, and concentration and numerical application.

Toward an Auditory Virtual Observatory

The large ecosystem of observations generated by major space telescope missions can be remotely analyzed using interoperable virtual observatory technologies. In this context of astronomical big data analysis, sonification has the potential of adding a complementary dimension to visualization, enhancing the accessibility of the archives, and offering an alternative strategy to be used when overlapping issues are found in purely graphical representations. This article presents a collection of sonification and musification prototypes that explore the case studies of the MILES and STELIB stellar libraries from the Spanish Virtual Observatory and the Kepler and TESS light curve databases from the Space Telescope Science Institute archive. Using automation and deep learning algorithms, it offers a “palette” of resources that could be used in future developments oriented toward an auditory virtual observatory proposal. The work includes a user study with quantitative and qualitative feedback from specialized and nonspecialized users analyzing the use of sine waves and musical instrument mappings for revealing overlapped lines in galaxy transmission spectra, confirming the need for training and prior knowledge for the correct interpretation of accurate sonifications, and providing potential guidelines to inspire future designs of widely accepted auditory representations for outreach purposes.

Biological basis of the aesthetic and rejuvenating effects in the skin after the application of the compressive microvibration Endospheres.

Compressive microvibration is a type of stimulation patented as Endospheres therapy. The stimulation, through Endospheres, applied externally to the skin surface, causes changes in the physiological and functional structure of tissues underneath the epidermis, including adipose tissue. Cyclic mechanical stress, induced by this therapy with its particular compressive microvibration, modifies the normal cell cycle of adipose tissue and promotes tissue remodelling due to the activation of the abundantly present mesenchymal-derived stem cells. In this study, a literature revision was performed to elucidate the mechanisms through which the repetitive, cyclic or modulated/ordered mechanical input of Endospheres, which results in harmonic compressive microvibrations, can have beneficial effects on the skin and all subcutaneous tissues up to the muscles, improving rejuvenation, tissue repair, vascularization and macro-organization. It was possible to formulate the hypothesis that the ordered frequency and oscillatory dynamics can completely change the chaotic and oscillatory patterns of mitochondria alongside the endoplasmic reticulum membrane in a recently discovered complex known as mitochondria-associated endoplasmatic reticulum membrane complex or mitochondria-associated endoplasmatic reticulum membrane. Analyzing the biochemical and physical characteristics of these structures, it was assessed that the nature of the benefits of the Endospheres stimulation of tissues could include three different origins: mechanical, linked to the transfer of mechanical inputs; biophysical, related to the chaotic biology of mitochondria, the generation of sinusoidal waves and the generation of piezoelectric forces; and biochemical, linked to the sensory function of adipose tissue. All these forces are discussed in detail.

High-Magnification Object Tracking with Ultra-Fast View Adjustment and Continuous Autofocus Based on Dynamic-Range Focal Sweep.

Active vision systems (AVSs) have been widely used to obtain high-resolution images of objects of interest. However, tracking small objects in high-magnification scenes is challenging due to shallow depth of field (DoF) and narrow field of view (FoV). To address this, we introduce a novel high-speed AVS with a continuous autofocus (C-AF) approach based on dynamic-range focal sweep and a high-frame-rate (HFR) frame-by-frame tracking pipeline. Our AVS leverages an ultra-fast pan-tilt mechanism based on a Galvano mirror, enabling high-frequency view direction adjustment. Specifically, the proposed C-AF approach uses a 500 fps high-speed camera and a focus-tunable liquid lens operating at a sine wave, providing a 50 Hz focal sweep around the object's optimal focus. During each focal sweep, 10 images with varying focuses are captured, and the one with the highest focus value is selected, resulting in a stable output of well-focused images at 50 fps. Simultaneously, the object's depth is measured using the depth-from-focus (DFF) technique, allowing dynamic adjustment of the focal sweep range. Importantly, because the remaining images are only slightly less focused, all 500 fps images can be utilized for object tracking. The proposed tracking pipeline combines deep-learning-based object detection, K-means color clustering, and HFR tracking based on color filtering, achieving 500 fps frame-by-frame tracking. Experimental results demonstrate the effectiveness of the proposed C-AF approach and the advanced capabilities of the high-speed AVS for magnified object tracking.

State Feedback Control of a Car and Beam Prototype

The Car and Beam prototype is a teaching piece of equipment, inspired by Ball and Beam systems. It consists of a beam supported in its center by means of a rotating axis installed in two rolling bearings, allowing the beam to rotate through the actuation of a servo motor. A car is coupled to this beam, and its displacement is measured using a linear encoder. This paper focuses on two key aspects: firstly, it offers a mathematical model of the Car and Beam system, and secondly, it outlines the development of a state-feedback tracking controller through pole placement to this system. To validate the modeling and control approach, we present simulation and experimental results using three different reference profiles: step, square wave, and sine wave. Our findings demonstrate the effectiveness of the control strategy in tracking predefined trajectories, both in simulation and with the physical prototype. In conclusion, this study highlights the efficacy of the methodology employed for mathematical modeling and the controller's design in the context of this specific application. The results indicate promising potential for further exploration in this domain.

Single-Stage MV-Connected Charger Using an Ac/Ac Modular Multilevel Converter

Modular multilevel converters with non-sinusoidal ac voltage output can reduce cost and volume in medium-voltage-connected electric vehicle battery charging applications. The use of full-bridge submodules in such converters enables single-stage ac/ac voltage conversion, allowing a medium-voltage grid to be directly connected to a medium-frequency isolation transformer. The application of a square wave voltage at the medium-frequency transformer’s single-phase port enhances the converter’s efficiency and power density in comparison to a sinusoidal voltage. This paper presents the analysis and modelling of a modular multilevel converter, comparing its operation with sinusoidal and square wave output voltages. A single control scheme for both output voltage waveforms is proposed for the three-phase and single-phase ac currents, circulating currents, and the energy stored in the submodule capacitors. The control strategy of the three-phase and single-phase port currents is verified through simulation and experiments using a scaled-down prototype, thereby validating its suitability for high-power bidirectional battery chargers.

Experimental Study on Small-Scale Shake Table Testing of Cable-Stiffened Single-Layer Spherical Latticed Shell

The cable-stiffened single-layer latticed shell is an innovative structural design that achieves a perfect balance between lightweight and stability by combining cables and a latticed shell. However, the study on dynamic response and failure mechanism of cable-stiffened single-layer latticed shell under seismic action is still lacking. Therefore, small-scale shaking table tests of two kinds of single-layer spherical latticed shells are carried out; the dynamic response and failure mode of the two shells under sine wave earthquake are investigated by using time history analysis. The conclusions show that the introduction of the prestressed cable plays an important role in improving the seismic performance of the single-layer latticed shell, and the cable-stiffened single-layer latticed shell has better load capacity and seismic performance under earthquake action than the ordinary single-layer latticed shell structure.

Comprehensive evaluation of the influence of PEM water electrolyzers structure on mass transfer performance based on entropy weight method

The proton exchange membrane water electrolyzer (PEMWE) has broad prospects in hydrogen production due to its green and efficient advantages. This paper comprehensively analyzes the performance and water-gas transport characteristics of PEMWE with different cell structures, in which polarization curves, flow velocity distribution, oxygen concentration, temperature, liquid water saturation, and pressure are investigated. Simultaneously, the study explores the effects of variations in inlet velocity, inlet temperature, porosity, and thickness of the anode porous transport layer (APTL) on the four flow fields. Finally, the technique for order preference by similarity to ideal solution (TOPSIS) based on entropy weight method is employed for a comprehensive evaluation of the flow fields. The results indicate that, compared to parallel flow field (PFF), sinusoidal wave flow field (SWFF), intercepted flow field (ICFF), and single-serpentine flow field (SSFF) exhibit stronger exhaust capabilities, with temperature uniformity increasing by 83.65 %, 59.24 %, and 70.15 %, respectively. However, the longer flow channel of SSFF results in a high pressure drop and lower liquid water saturation. An increase in inlet velocity leads to a decrease in temperature, causing an increase in voltage, as higher temperatures reduce activation and ohmic overpotentials. Additionally, an increase in the porosity and thickness of APTL deteriorates the polarization performance of PEMWE. The research results of this study can provide valuable assistance for the future design of PEMWE.

Resonant fiber optic gyroscope driven by a broadband light source based on an over-coupled state fiber ring resonator

The resonant fiber optic gyroscope (RFOG) driven by a broadband light source has advantages over conventional RFOGs in terms of structure, solution, etc., and provides new ideas for the commercialization of RFOGs. In this paper, the basic working principle of RFOG driven by a broadband light source is introduced. The optimal modulation coefficients are provided for sinusoidal wave modulation. The influence of the length of the fiber-optic ring resonator (FRR) and the coupling coefficient of the fiber coupler on the sensitivity is analyzed. The FRR is constructed in the over-coupled state to improve the utilization of optical power, and thus significantly increase the system sensitivity. In experiments, an RFOG prototype with a diameter of 13 cm, a height of 7 cm, and a fiber ring length of 210 m is produced. A bias instability (BI) of 0.06°/h and an angular random walk (ARW) of 0.01∘/h are obtained.

Investigation and improvement of spill quality at XiPAF synchrotron

The Xi’an 200 MeV Proton Application Facility (XiPAF) is a specialized facility designed to simulate space radiation environments. To meet the requirements of space radiation simulation, the proton accelerator must provide a quasi-continuous spill. The facility has achieved this goal by implementing third-order resonance and RF knockout (RF-KO) slow extraction. In this study, the source of the spill ripple at the XiPAF synchrotron was analyzed and a method was developed to calculate the fluctuation ratio of the spill from the spill spectrum. According to the experimental results, the spill quality at XiPAF is mainly affected by the ripple of the magnet power supply. To improve the spill quality, the frequency spectrum of the excitation signal was optimized to suppress the influence of the power supply ripple. We found that the dual-frequency signal, which consists of the two sinusoidal waves corresponding to the extraction and diffusion regions in the third-order resonance, can significantly reduce the influence of the magnet power supply ripple. After adopting the optimized dual-frequency signal, the fluctuation ratio of the spill is reduced from about 0.15 to 0.092 (sample median) at a sampling frequency of 1.24 kHz.

Superconducting Diode Effect in a Constricted Nanowire

AbstractDue to isotropic superconducting properties and the lack of breaking of inversion symmetry for conventional s‐wave superconductors, a nonreciprocal superconducting diode effect is absent. Recently, a series of superconducting structures, including superconducting superlattice, and quantum‐material‐based superconducting Josephson junction, have exhibited a superconducting diode effect in terms of polarity‐dependent critical current. However, due to complex structures, these composite systems are not able to construct large‐scale integrated superconducting circuits. Here, it is demonstrated that the minimal superconducting electric component‐superconducting nanowire‐based diode with a nonreciprocal transport effect under a perpendicular magnetic field, in which the superconducting to normal metallic phase transition relies on the polarity and amplitude of the bias current. These nanowire diodes can be reliably operated near at all temperatures below the critical temperature, and the rectification efficiency at 2 K can be more than 24%. Moreover, the superconducting nanowire diode is able to rectify both square wave and sine wave signals. Combining the superconducting nanowire‐based diodes and transistors, superconducting nanowires hold the possibility to construct novel low‐dissipation superconducting integrated circuits.

Highly controlled multiplex electrospinning

Applications of electrospinning (ES) range from fabrication of biomedical devices and tissue regeneration scaffolds to light manipulation and energy conversion, and even to deposition of materials that act as growth platforms for nanoscale catalysis. One major limitation to wide adoption of ES is stochastic fiber deposition resulting from the chaotic motion of the polymer stream as is approaches the deposition surface. In the past, fabrication of structures or materials with precisely determined mesoscale morphology has been accomplished through modification of electrode shape, use of multi-dimensional electrodes or pins, deposition onto weaving looms, hand-held electrospinning devices that allow the user to guide deposition, or electric field manipulation by lensing elements or apertures. In this work, we demonstrate an ES system that contains multiple high voltage power supplies that are independently controlled through a control algorithm implemented in LabVIEW. The end result is what we term “multiplex ES” where multiple independently controlled high-voltage signals are combined by the ES fiber to result in unique deposition control. COMSOL Multiphysics® software was used to model the electric field produced in this novel ES system. Using the multi-power supply system, we demonstrate fabrication of woven fiber materials that do not require complex deposition surfaces. Time-varied sinusoidal wave inputs were used to create electrospun torus shapes. The outer diameter of the tori was found, through parametric analysis, to be rather insensitive to frequency used during deposition, while inner diameter was inversely related to frequency, resulting in overall width of the tori increasing with frequency. Multiplex ES has a high-frequency cutoff based on the time response of the high voltage electrical circuit. These time constants were measured and minimized through the addition of parallel resistors that decreased impedance of the system and improved the high-frequency cutoff by up to 63%.

Experimental study of wire arc additively manufactured steel sections stiffened by sinusoidal waves

Numerical models and initial tests conducted on specimens produced using selective laser melting have indicated that structural sections may be stiffened by imposing sinusoidal waveforms on their geometries which delay buckling and improve the overall buckling resistance. Wire arc additive manufacturing (WAAM) stands out as the most promising additive manufacturing technique for fabricating sections of the scale required in the construction industry, however, there is currently a lack of understanding of how the undulating surface finish inherent to WAAM will affect the stiffening effect of the sinusoidal waveforms. Therefore, this paper details an experimental study involving ten WAAM equal angle sections stiffened with two different sinusoidal wave patterns identified as the optimal patterns in previous numerical analysis. The production, geometric measurement and testing of the sections are described and the material properties of the WAAM material are determined. All equal angle section specimens tested fall within Eurocode 3 Class 4 and the stiffening wave patterns are shown to benefit the slenderer sections more. Comparative analysis between the material consumption and relative strength is provided, highlighting the potential for sinusoidal WAAM sections to improve the material efficiency and facilitate economic design practices within the steel construction industry.

Low-Level Auditory Processing Correlates With Language Abilities: An ERP Study Investigating Sequence Learning and Auditory Processing in School-Aged Children.

Auditory processing and procedural learning deficits have been associated with language learning difficulties. We investigated the relationship of these skills and school-age language abilities in children with and without a history of late talking using auditory event related potentials (ERPs). Late talking (i.e., slow early language development) increases the risk of persistent language difficulties, but its causes remain unknown. Participants in this study were children with varying language abilities (n = 60). Half of the participants (n = 30) had a history of late talking. We measured procedural learning by manipulating the predictability of sine tone stimuli in a passive auditory ERP paradigm. Auditory processing was tested by examining how the presence of noise (increasing perceptual demands) affected the ERPs. Contrary to our hypotheses on auditory processing and language development, the effect of noise on ERPs did not correlate with school-age language abilities in children with or without a history of late talking. Our paradigm failed to reveal interpretable effects of predictability leaving us unable to assess the effects of procedural learning. However, better language abilities were related to weaker responses in a 75-175 ms time window, and stronger responses in a 150-250 ms time window. We suggest that the weak early responses in children with better language ability reflect efficient processing of low-level auditory information, allowing deeper processing of later, high-level auditory information. We assume that these differences reflect variation in brain maturation between individuals with varying language abilities.

Estimation of electric field inside a neural spheroid by low‐frequency magnetic field exposure

AbstractExposure to time‐varying, low‐frequency and high‐intensity magnetic field (MF) induce electric field (EF) inside the human body, producing stimulus effects such as nerve fiber excitation or synaptic modulation. To measure such stimulus effects by low‐frequency MF exposure in real‐time, we developed a fluorescent recording system using optical fibers that is neither affected by the MF nor affects the MF distribution. In this study, a numerical calculation model composed of voxels with a 6.25 µm spatial resolution was developed. Using this numerical model, we evaluated the distribution of the EF generated inside three‐dimensional neuronal tissue called neural spheroid, under 50 Hz sinusoidal wave, 300 mT (root mean square) uniform MF exposure. We also investigated the influence of the optical fiber on the electric field distribution in neural spheroid. As a result, MF produced an induced EF in the neural spheroid of more than 4 V/m, well above the theoretical threshold of synaptic modulation. These results indicated that our experimental system was suitable for the evaluation of the threshold of stimulus effects using neural spheroid.

Comparative Analysis of Bipolar and Unipolar SPWM Techniques in PIC-Based Pure Sine Wave Single-Phase Inverters

This paper provides a comparative analysis of bipolar versus unipolar Sinusoidal Pulse Width Modulation (SPWM) in DC-AC inverters, focusing on Total Harmonic Distortion (THD) across modulation indices and the latter’s effects on the R-L loads. Using the PIC18F2431 microcontroller for its efficiency, a single-phase inverter accomplished to deliver a high-fidelity sine wave. This study discovered that while both SPWM methods reduce harmonics, the unipolar approach yields more uniform THD reduction and superior performance, particularly noticeable in RL load conditions, where minimal harmonic distortion is crucial. The bipolar inverter, despite a higher initial THD, shows a considerable improvement at higher indices, significantly enhanced by an LC low-pass filter. This filter is a key component in achieving sub-1% THD levels at full modulation, ensuring optimal sine wave quality. The findings highlight the operational differences between the SPWM techniques and the importance of the LC filters in ameliorating the inverter output for various power applications.

Enhancing defect detection in solid materials using low-duty cycle square wave lock-in thermography: a time-efficient and quantitative approach

Lock-in thermography has been used to detect material defects but has faced challenges in quantitatively identifying defects. Traditional methods with a sine wave or symmetrical square wave heat source require time-consuming frequency adjustments with multiple experiments. This study introduces a novel technique using a heat source of a low-duty cycle square wave in lock-in thermography. This harmonic-rich heat source provides information on the blind frequency and the depth of defects, significantly reducing testing time. This method was validated by finite element simulations, which generated phase maps and phase difference-frequency curves at multiple frequencies that located defects. The study explored the correlation between thermal diffusion length at the blind frequency and defect depth and the impact of transverse thermal diffusion on depth measurement. The findings indicate that phase maps at the optimal frequency are most suitable for measuring defect edges. This approach offers a promising, time-efficient, and quantitative solution for defect detection.

Programmable Analogue Drawing Machines, 1952–2023

Abstract The author discusses his work creating programmable, generative analogue drawing machines over six decades in the context of the constructivist tradition and influenced by the Bauhaus German art school and the subsequent art, science, and technology movement. During the first three decades he developed a variety of machines and from 1990 followed a more analytical approach focusing on randomness, chaos, and subjectivity in art. This progressed to the author’s PhD research program wherein he investigated innovative analogue programming systems that employed direct current motors, linkages, and cranks together with programmers, actuating motors for a variety of timed pulses. These enabled variables such as pen-lift and rotation, forward/reverse pen action, light drawing, sine waves, turntable and drum machines, and versions of X:Y plotters.

Research on loss characteristic of soft magnetic composites under nonsinusoidal excitations with DC bias field

Choosing a suitable core loss model and accurately predicting energy loss are crucial in designing magnetic devices with high efficiency based on soft magnetic composites (SMCs). In this work, FeSiAl and FeSi SMCs with a uniform insulating layer were fabricated by a phosphating process. The effects of excitation waveform and DC bias field on core loss have been investigated in depth. The results show that different remagnetization rates of SMC under ideal sinusoidal and square waves result in different core losses at the same frequency and flux density. The improved general Steinmetz equation and the modified Steinmetz equation were shown to be suitable for calculating core loss under square excitation waves without DC bias field. When the DC bias field is applied, the core loss of FeSiAl and FeSi SMCs was found to increase significantly due to the magnetization state gradually approaching saturation. Interestingly, the variation tendency of core loss can be accurately predicted using the waveform coefficient Steinmetz equation under square excitation conditions with a DC bias environment. This work not only provides deep insights into core loss under different excitation waveforms and DC bias fields but also determines the application scope of different core loss models.