Excitation Source Research Articles

A DPIM-based probability analysis framework to obtain railway vehicle vibration characteristics considering the randomness of OOR wheel

The OOR (out-of-roundness) wheel is one of the main excitation sources causing vehicle vibration. However, the OOR wheel occurs randomly, indicating that the vibration behavior of a vehicle cannot be comprehensively evaluated using a deterministic approach. Thus, a probability analysis framework is proposed to obtain vehicle vibration characteristics while considering the randomness of the OOR wheel. The probability model of the random OOR wheel is derived by reducing the high-dimensional variables into a few independent variables of the radius, amplitude, and phase. Then, the vertical vehicle-track coupled system with OOR wheels is modelled. A DPIM (direct probability integral method) is further developed to analyze the evolution of excitation to response probabilities. Finally, the statistics of the random vibration of the vehicle are calculated. The proposed framework is verified using a numerical case. Results show that the PDF (probability density function) shape of the vehicle random vibration, induced by the Gaussian-distributed OOR wheel, deviates from the Gaussian distribution due to the nonlinear wheel/rail contact force. Instead, it exhibits a right-skewed shape, significantly impacting the dynamic performance. As the mean or coefficient of variation of the OOR wheel amplitude increases linearly, the reliability of the vehicle Sperling index experiences a quadratic or double-sloping decrease. Consequently, a maintenance threshold for OOR wheel amplitudes is given based on reliability considerations. Compared to Monte Carlo simulation, the proposed framework offers a computational efficiency improvement of at least one order of magnitude.

Broadband near-infrared (NIR) emitting Cr3+ -doped La3 Ga5 SnO14 phosphor with long persistent and photostimulated persistent luminescence.

Recently, long persistent phosphors (LPPs) have attracted significant attention as promising candidates for biomedical applications. However, the serious decrease in luminescence intensity in tissue still remains a major challenge. Therefore, exploring more competitive LPPs and achieving reproducible tissue imaging is crucial. In this study, a new series of near-infrared (NIR) phosphors La3 Ga5 Sn1-x O14 :xCr3+ (x = 0.005-0.05) were synthesized using a high-temperature solid-state method. The as-synthesized samples were characterized using X-ray diffraction, diffuse/photoluminescence spectroscopy, fluorescence decay curves, and thermoluminescence spectroscopy. Upon excitation with ultraviolet light, strong emission bands were observed in the range 600-1200 nm with an optimal doping concentration of x = 0.02mol. Moreover, La3 Ga5 SnO14 :Cr3+ exhibits persistent luminescence due to the presence of suitable energy traps, which prompted the phosphor to emit NIR light even after the removal of the excitation source.

A new method for direct extraction of ambipolar diffusion length in a thin film by scanning photoluminescence microscopy

In this study, we demonstrate a new method of scanning photoluminescence (PL) microscopy (SPLM) to directly extract the ambipolar diffusion length in a GaAs thin film. The PL intensity of the GaAs thin film was recorded while the excitation source scanned along a 400 nm wide slit between the metal masks to avoid the influence of surface recombination and light scattering at the sample edge. The experimental SPLM profile showed a simple-exponential-decay functional form and was numerically verified. A fitted decay length of 723 nm was extracted, which represents the ambipolar diffusion length of the GaAs thin film and agrees well with our previous study.

Design and Analysis of a New Dual-Stator Hybrid Magnet Flux Modulation Machine

This paper proposes a new dual-stator hybrid-magnet flux modulation machine (DS-FMHMM) for direct-drive applications, which employs NdFeB magnet excitation and Ferrite magnet excitation on the rotor and outer stator sides, respectively. With this design, the proposed DS-FMHMM can not only fully use the bidirectional flux modulation effect, but also effectively alleviate the magnetic saturation issue. The machine configuration is described, together with the operating principle. Then, the design parameters of DS-FMHMM are globally optimized for obtaining high torque quality, and the influence of magnet dimensions on torque is analyzed. To evaluate the merits of the proposed DS-FMHMM, the electromagnetic performances of machines under different magnet excitation sources are analyzed, and a comprehensive electromagnetic performance comparison of DS-FMHMM and two existing dual-stator flux modulation machines (DSFMMs) is developed.

Development of a droplet cathode glow discharge excitation source for high throughput detection of Li, Ca and K in serum samples

Sensitive and high-throughput analysis of trace elements in biological samples with limited volume is of great significance for clinical studies.

ICONS CONSERVATION AND PIGMENTS IDENTIFICATION OF THE SACRED ICONS PAINTER ANTONIOS AGORASTOS

The sacred icon painter Antonios Agorastos became known after the recording of his inscribed icons in Skopelos by Pavlos Lazaridis, covering a period of 30 years 1667-1703. The signed icons that we studied in Tyrnavos are the two icons of the Virgin Mary and Christ in the iconostasis of the church of Saint Anargyros on either side of the Beautiful Gate. The aim of the research is the study of the pigments of the hagiographer and the evaluation of other nonsigned icons. In a golden background, the Virgin Mary is depicted enthroned in the form of the Infant. She is depicted sitting frontally holding Christ in front of her. At the bottom right is an inscription with the painter's name, by the hand of Antonios sub deacon Agorastos Kritos (1668). Also, in a golden background, Jesus Christ is depicted enthroned in the type of Pantocrator. With his right hand he blesses and with his left he holds an open evangelist painting of holy icons. For the measurements of the pigments in the icons, the following techniques were used: a) Raman spectroscopy Thunder Optics - Gem Raman System with 532nm laser excitation, while before identification, the spectra were subjected to a procedure such as baseline correction, Savitzky - Golay smoothing - normalization and b) the XRF spectrometer Niton XLp 818 technique with an excitation source of 241 Αm. Analysis of Raman and XRF spectra was performed with the help of Spectragryph software. The identification of pigments using the two complementary techniques revealed the use of a variety of inorganic pigments such as lead white, copper green (verdigris), copper blue (azurite), for yellow (realgar), iron ochres (red and yellow) and cinnabar for the red colour.

A miniaturized microplasma excitation source coupled with photochemically induced volatile species generation as a cost-effective tool for in situ mercury pollution analyses

A portable, miniaturized atmospheric microplasma discharge system coupled with the photochemical vapour generation was developed for the sensitive Hg determination in water samples using OES.

Unveiling BiVO4 photoelectrocatalytic potential for CO2 reduction at ambient temperature

An optimistic system for CO2 reduction! This study employs BiVO4 as a cathode catalyst by a photoelectrochemical method. Different tests were performed by altering the excitation source and photo- and electrochemical methods were compared.

A reversible photoelectrochemical microsensor for dynamically monitoring sulfur dioxide in the epileptic brain.

Epilepsy is considered one of the most prevalent neurological disorders, yet the precise mechanisms underlying its pathogenesis remain inadequately elucidated. Emerging evidence implicates endogenous sulfur dioxide (SO2) in the brain as playing a significant role in epilepsy and associated neuronal apoptosis. Consequently, tracking the dynamic fluctuations in the levels of SO2 and its derivatives (SO32-/HSO3-) provides valuable insights into the molecular mechanisms underlying epilepsy, with potential implications for its diagnosis and therapeutic intervention. Nonetheless, the absence of reversible in vivo detection tools constitutes a formidable obstacle in the real-time monitoring of SO2 dynamics in the brain. In response to this challenge, we propose a novel approach involving a photoelectrochemical (PEC) microsensor capable of reversibly detecting SO2. This microsensor leverages a reversibly recognizing dye for SO2 and upconversion nanoparticles as the modulator of the excitation source for the photoactive material, enabling modulation of the photocurrent by the target. The reversible output of PEC signals allows for the monitoring of SO2 levels in real time in the brains of epileptic mice. This study reveals the patterns of SO2 level changes during epilepsy and provides insights into the neuroprotective mechanism of exogenous SO2.

Optimum design of planetary gear set using multi-objective optimization considering mass, power loss and transmission error

In this study, a multi-objective optimal design of a planetary gear set was performed considering mass, power loss, and transmission error. In particular, the results were analyzed from a novel perspective. The implemented multi-objective optimal design methodology minimizes the mass, power loss, and vibration with respect to seven macro-geometry variables. The peak-to-peak static transmission error (PPSTE) of each gear pair corresponds to the excitation source of the planetary gear set, and reducing the PPSTE helps minimize vibration. Thus, the PPSTE was calculated using the time-varying mesh stiffness obtained through an analytical model. The non-dominated sorting genetic algorithm-III (NSGA-III) was implemented as a multi-objective optimization algorithm, and the criteria importance through the inter-criteria correlation method was implemented for quantitative comparison purposes regarding the combination of objective functions. The results showed that obtaining an optimal macro-geometry design for a planetary gear set exhibiting good performance required simultaneous consideration of the mass, power loss, and vibration. Furthermore, the results confirmed that a versatile optimization algorithm, such as NSGA-III, should be used to capture the discontinuous solution distribution owing to various constraints of the planetary gear set.

Evaluation of a Portable Arduino-based Mini Spectrometer Prototype for Cells Optical Density Measurement

Cell optical density (OD) measurement is essential for tracking the progress of microbial fermentation processes. It is typically performed through a spectrophotometer at the wavelength of 600 nm. In this paper, a portable Arduino-based mini spectrometer prototype is presented. In the proposed prototype, a turbidity sensor was utilized to perform the optical density measurement of cells based on the Beer’s Lambert law. Differences on the light intensity from the excitation source and the collective point were correlated with the known cell concentration (using S. cerevisae yeast with concentration between 1 g/L and 5 g/L). The data attained was used as the standard curve and also to validate the functionality of the device. Fermentation experiments were carried out and the progress of the fermentation were measured using the proposed OD sensing prototype and compared to the standard bench top spectrometer. Both devices produced a calibration curve with R-squared value greater than 0.95 (0.95 for bench spectrometer and 0.97 for the Arduino device) and a comparable fermentation curve attained from both devices highlighted the workability of the proposed prototype. In addition, the device has a small footprint, portable and affordable.

FEATURES OF USING TARGETS WITH PENETRATING RADIATION IN THE X-RAY RADIOMETRIC METHOD

When analyzing and selecting elements using the X-ray radiometric method, characteristic beams obtained from targets are often used as a radioactive source of primary excitation in measuring instruments. The geometry of targets with reflected radiation currently used in measuring instrument sensors creates certain inconveniences, both in terms of their size and due to the creation of additional disturbing rays of the flashlight passing through the layer layer from the original one. source and directly includes the detector. These disadvantages become more obvious with X-ray radiometric logging. To avoid these shortcomings and inconveniences, we propose a new approach to the use of targets, the essence of which is to use not reflected, but secondary rays generated in the target and passing through it. In this case, the target is placed at right angles to the radiation trajectory of the primary source, as a result of which characteristic X-rays of the target appear, the energy of which is less than the energy of the k-edge of absorption of their material, pass through it unhindered and appear in the primary spectrum, representing themselves as their analytical line. The specified geometry of the installation is realized by simply replacing the protective layer of the radioactive beryllium isotope with a target in the probe.

Vibro-Acoustic Analysis of an Underwater Cylindrical Shell with Internal Structures and a Comparison with Experiment

Abstract: In this work, the low-frequency vibration response and full-band acoustic radiation characteristics of an underwater reinforced cylindrical shell with internal structures are studied by combining the FEM with SEA. The stiffened cylindrical shell contains internal structures such as the F-shape plates and the support valve frames. The exciting sources have two different exciting forces corresponding to two experimental conditions. In the low-frequency band, the FEM was employed, and in the medium and high-frequency bands, the SEA was used. A comparison of the numerical results and the experiment shows that they agree well. The FEM and SEA give better results at [1,1k] Hz and [1k,10k] Hz, respectively. Due to mesh quality limitations, the FEM is not favorable for medium and high-frequency calculations. The SEA focuses on the structural mean power flow but cannot obtain position-specific vibrational responses. The results show that the internal excitation source mainly causes the structural vibration and sound radiation and are closely related to the free vibration characteristics of the structure. In addition, with the increase in frequency, the circumferential sound pressure level of the underwater structure has more substantial directivity.

Efficient Zero-Sequence Impedance Measurement in Autotransformers Using Low-Voltage Excitation

In accordance with the IEEE standard, the zero-sequence impedance test of transformers necessitates an open or short circuit test on the high-voltage side winding. Power source excitation is applied to the high-voltage test winding using a high-capacity test power supply. To circumvent the need for a large-capacity, high-voltage test power supply in field tests, this paper proposes a method for measuring zero-sequence impedance in autotransformers based on low-voltage excitation and disconnection testing. By applying a three-phase power supply to the lowest voltage side of the autotransformer and creating a disconnection condition, an unbalanced test scenario is established. Subsequently, the composite sequence network equivalent circuit for one-phase and two-phase disconnections between the high-voltage side and the low-voltage side of the transformer is formulated. Calculation formulas for the zero-sequence impedance of the autotransformer under various conditions are derived. The accuracy of the zero-sequence impedance is verified using MATLAB/Simulink simulation software 2018b, evaluating double-winding and three-winding autotransformers in breaking tests under different connection modes. The error is found to be less than 3%. The results of this study affirm the high accuracy of the proposed method.

Three-Dimensional Forward Modeling of Transient Electromagnetic Method Considering Induced Polarization Effect Based on Spectral Element Method

The transient electromagnetic method (TEM) is widely used in the exploration of mineral, petroleum, and geothermal resources due to its sensitivity to low-resistivity bodies, limited site constraints, and strong resistance to interference. In practical applications, the TEM often uses a long wire source instead of an idealized horizontal electric dipole (HED) source as the excitation source. This is due to the complex external conditions and the relatively large distance between the receiving zone and the transmitter source. Compared to the HED, the long wire source can provide a larger excitation current, generating stronger signals to meet the requirements of a higher signal-to-noise ratio or deeper exploration. It also produces longer-duration signals, thereby providing better resolution. Additionally, for the interpretation of TEM data, three-dimensional forward modeling plays a crucial role. However, the mature traditional TEM forward method is based on a simple, sometimes inappropriate model, as it is well established that the induced polarization (IP) effect is widely present in the deep earth, especially in oil and gas reservoirs. The presence of the IP effect results in negative responses in field data that do not conform to the traditional theoretical decay law of TEM, which can significantly impact data processing and inversion results. To address this issue, a TEM forward modeling method considering the IP effect based on the spectral element method (SEM) has been developed in this study. Firstly, starting from the Helmholtz equation satisfied by the time domain electric field, we introduce the Debye model with polarization information into the forward modeling by utilizing the differential form of Ohm’s law. As a result, we derive the boundary value problem for the time domain electric field that considers the induced polarization effect. Using Gauss–Lobatto–Legendre (GLL) polynomials as the basis functions, the SEM is employed to discretize the governing equations at each time step and obtain spectral element discretization equations. Then, temporal discretization equations are derived using the second-order backward Euler formula, and the linear system of equations is solved using the Pardiso direct solver. Finally, the electromagnetic responses at any time channel are obtained via SEM interpolation and numerical integration, thereby achieving three-dimensional TEM forward modeling considering the IP effect. The results indicate that this method can effectively reflect the spatial distribution of polarizable subsurface media. It provides valuable references for studying the polarization parameters of subsurface media and performing a three-dimensional inversion of TEM data considering the induced polarization effect.

In situ doped Cs2AgIn0.9Bi0.1Cl6:8%Yb,2%Er/PVDF composite films for the printing of multimodal fluorescent anti-counterfeiting marks

The fluorescent anti-counterfeiting technology has become one of the most desirable candidates in practical anti-counterfeiting applications owing to its adjustable emission, high recognition and design flexibility. However, the security level of single emitting fluorescent materials was lower, and no longer able to cope with current forgery techniques, so the development of higher level multimodal fluorescent anti-counterfeiting technologies was urgent. In this report, lead-free double perovskite (DP) material CsAgBiCl6 was chosen as the host and a technique for in situ growth in polymer polyvinylidene difluoride (PVDF) was proposed to obtain large-scale high-quality Cs2AgBiCl6/PVDF composite films (CFs). Subsequently, the Cs2AgIn0.9Bi0.1Cl6:8%Yb,2%Er/PVDF CFs with both down-conversion and up-conversion optical properties was achieved by hybrid (In3+/Yb3+/Er3+) doping, which was able to displayed inconsistent fluorescence emission (orange and green) under different excitation sources, and their fluorescence intensities exhibited tunability with the change of the environmental temperature, greatly enhancing its competitiveness in the field of fluorescent anti-counterfeiting. Finally, different anti-counterfeiting marks have been designed by the screen-printing process, and the complex encryption once again ensured the security of the information, while bringing a new gospel to the subsequent development of lead-free DP materials.

Plasmon-enhanced optoacoustic transducer with Ecoflex thin film for broadband ultrasound generation using overdriven pulsed laser diode.

Ultrasonic transducers facilitate noninvasive biomedical imaging and therapeutic applications. Optoacoustic generation using nanoplasmonic structures provides a technical solution for highly efficient broadband ultrasonic transducer. However, bulky and high-cost nanosecond lasers as conventional excitation sources hinder a compact configuration of transducer. Here, we report a plasmon-enhanced optoacoustic transducer (PEAT) for broadband ultrasound generation, featuring an overdriven pulsed laser diode (LD) and an Ecoflex thin film. The PEAT module consists of an LD, a collimating lens, a focusing lens, and an Ecoflex-coated 3D nanoplasmonic substrate (NPS). The LD is overdriven above its nominal current and precisely modulated to achieve nanosecond pulsed beam with high optical peak power. The focused laser beam is injected on the NPS with high-density electromagnetic hotspots, which allows for the efficient plasmonic photothermal effect. The thermal expansion of Ecoflex finally generates broadband ultrasound. The overdriven pulsed LD achieves a maximum optical peak power of 40W, exceeding the average optical power of 3W. The thick Ecoflex-coated NPS exhibits an eightfold optoacoustic enhancement with a fractional bandwidth higher than 160% and a peak frequency of 2.5MHz. In addition, the optoacoustic amplitude is precisely controlled by the optical peak power or the laser pulse width. The PEAT-integrated microfluidic chip clearly demonstrates acoustic atomization by generating aerosol droplets at the air-liquid interface. Plasmon-enhanced optoacoustic generation using PEAT can provide an approach for compact and on-demand biomedical applications, such as ultrasound imaging and lab-on-a-chip technologies.

Smart and low-cost fluorometer for identifying breast cancer malignancy based on lipid droplets accumulation.

The most common cause of breast cancer-related death is tumor recurrence. To develop more effective treatments, the identification of cancer cell specific malignancy indicators is therefore critical. Lipid droplets are known as an emerging hallmark in aggressive breast tumors. A common technique that can be used for observing molecules in cancer microenvironment is fluorescence microscopy. We describe the design, development and applicability of a smart fluorometer to detect lipid droplet accumulation based on the emitted fluorescence signals from highly malignant (MDA-MB-231) and mildly malignant (MCF7) breast cancer cell lines, that are stained with BODIPY dye. This device uses a visible-range light source as an excitation source and a spectral sensor as the detector. A commercial imaging system was used to examine the fluorescent cancer cell lines before being validated in a preclinical setting with the developed prototype. The outcomes indicate that this low-cost fluorometer can effectively detect the alterations levels of lipid droplets and hence distinguish between "moderately malignant" and "highly malignant" cancer cells. In comparison to prior research that used fluorescence spectroscopy techniques to detect cancer biomarkers, this study revealed enhanced capability in classifying mildly and highly malignant cancer cell lines.

Chaotic Characteristic Analysis of Spillway Radial Gate Vibration under Discharge Excitation

This paper aims to assess the nonlinear vibration of a radial gate induced by flood discharge; the measured acceleration response data of a spillway radial gate are analyzed using the chaos theory. The results show that the vibration responses of the gate at three opening heights present clear chaotic characteristics, and the chaotic characteristics of the lower main beam point are greater than other points. Moreover, the y-direction (vertical) correlation dimensions of the three measuring points on the supporting arm are larger than those of the x-direction (axial) and z-direction (lateral). The vertical vibration of the supporting arm is more complex and presents more uncertainties, which should be paid attention to in the literature. Under three different gate opening heights, the maximum Lyapunov exponent of each measuring point ranges from 0.0246 to 0.0681. In addition, the flow fluctuation load is the main excitation source of the gate vibration chaotic characteristics.

Solution combustion synthesis of Dy3+doped La2O3 nanoparticles: An investigation of their structural, optical and photoluminescence characteristics

The impact of the varying Dy3+ (1–9 mol %) rare earth ion concentration on the structural and luminous characteristics of La2O3 phosphors was studied via solution combustion synthesis. Structure formation, photoluminescence (PL) effectiveness, optical properties, and energy transfer mechanisms were examined in detail. All the synthesised samples exhibits hexagonal structure, which is supported by X-ray diffraction patterns (space group: P-3 mL (164)). Scanning electron microscope analysis shows irregular particle size and shapes of the synthesised materials. The presence of prominent and dominant Dy3+ ion peaks in the excitation spectrum of the ideal sample material, correlate to the Dy3+ ion's absorption peaks, supports the existence of considerable energy transfer among La3+ and Dy3+ ions. The PL emission wavelengths at 486 and 570 nm assigned to the Dy3+ ions transitions 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 respectively owing to the charge-transfer between La3+ and Dy3+ ions. PL emission intensity increases up to 3 mol% and afterwards it starts to decrease due to concentration quenching caused by non-radiative interactions. Photometric properties were investigated to check the possible utilization of La2O3:Dy3+ phosphor in white light emitting diodes application with CIE (x- 0.3468, y- 0.3986), CCT (0.1957, 0.5060), and colour purity (23.8 %). Aforementioned findings suggest that the synthesized phosphor is a viable option for making w-LEDs using NUV chips serving as the source of excitation.