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The double layer present at the interface of an electrode and an analyte causes electrode polarization (EP) in impedance spectroscopy, which hinders acquiring the actual impedance of biological samples at a lower frequency region. In this work, a novel carbon paste (CP) electrode material prepared by mixing the pencil graphite powder with transparent glue has been reported to reduce the EP by depositing its two coplanar electrodes on a chromatography paper substrate. Furthermore, two other devices having silver paste and pencil electrodes on the chromatography paper have been fabricated, analyzed for the EP, and compared with the CP electrode. The EP is quantified by fitting the impedance data to an equivalent electrical circuit having double layer capacitance as a constant phase element, and the CP electrode shows the lowest EP among the electrodes. The cyclic voltammetry analysis reveals blocking electrode property of the CP, which diminishes dc current flow at the electrode/electrolyte interface. Furthermore, the chromatography paper is found to increase the effective surface area of the deposited electrode by enhancing its surface roughness, which helps reduce the EP. [ABSTRACT FROM AUTHOR]

In the present work, nanoparticles of copper and silver synthesized via pulsed laser ablation of the respective targets in distilled water are applied to cellulose filter paper to check their effectiveness in the annihilation of bacteria from contaminated water. The treatment of the filter paper with the nanoparticles is found to be an excellent way to get rid of two common bacteria, Staphylococcus aureus and Escherichia coli, from contaminated water. The spread plate method on agar, employed to test the antibacterial efficacy of the nanoparticle-treated papers, clearly shows the absence of bacterial growth upon coming into contact with the nanoparticles in the filter paper. These results were further substantiated by the growth kinetic study of the bacteria that exhibited slow growth of the bacteria that were exposed to the nanoparticles. The morphology of the bacteria that came into contact with the nanoparticles is found to be adversely affected by the nanoparticles. Both copper and silver nanoparticles show a similar extent of antibacterial activity. [ABSTRACT FROM AUTHOR]

We developed and characterized a paper-based microfluidic sensor for the on-site diagnosis of drought stress in plants. Proline was used as a biomarker for analyzing drought stress, which was extracted by a colorimetric method using the proline-ninhydrin reaction. Paper was used as the main sensor material for the on-site detection of proline as it is easily transportable and cost-effective. The paper-based sensor was fabricated using wax-printing and origami methods, and the sensor was precoated with ninhydrin to allow for easy and convenient on-site use. Furthermore, a sample-to-ninhydrin ratio of 1:2 was found to confer optimal sensitivity to the drought diagnosis sensor. The concentration of proline in a sample was quantified by red-green-blue analysis to determine the change in green color intensity levels in response to distinct proline concentrations, which were detected by the sensor. The limit of detection of proline using the devised sensor was 657 µM, and the green color intensity level decreased with increasing proline concentration. In addition, the sensor was validated in an experimental drought stress model with Arabidopsis and subjected to drought stress for 21 days, and the amount of proline detected was 10 mM. The devised paper-based microfluidic sensor highlights the possibility of the on-site evaluation of drought stress in plants with potential to be utilized in various agricultural areas in the future.

Accurate measurement of the moisture content of paper is essential in papermaking and is also important in some paper-based microfluidic devices. Traditional measurement techniques provide very limited spatiotemporal resolution and working range. This article presents a novel method for moisture content measurement whose operating principle is the strong correlation between the optical transparency of paper and its moisture content. Spectrographic and microscopic measurement techniques were employed to characterize the relation of moisture content and relative transparency of four types of paper: hardwood chemi-thermomechanical pulp paper, Northern bleached softwood kraft paper, unbleached softwood kraft paper, and General ElectricR Whatman grade 1 chromatography paper. It was found that for all paper types, the paper transparency increased monotonically with the moisture content (as the ratio of the mass-of-water to the mass-of-dry-paper increased from 0% to 120%). This significant increase in relative transparency occurred due to the refractive index matching role of water in wet paper. It is further shown that mechanical loading of the paper has little impact on the relative transparency, for loadings that would be typical on a paper machine. The results of two transient water absorption experiments are presented that show the utility and accuracy of the technique. [ABSTRACT FROM AUTHOR]

Diffusion dynamics of water and oil are observed in real-time using video images. Savitzky–Golay derivative filtering ensures accurate localization of the liquid front. System identification demonstrates that a fractional-order model with only two parameters may be used to describe the dynamics of the diffusion process. The method paves the way for video-based cellulose filter paper microfluidics and lateral flow assays, which are low cost and have broad diagnostic applications. [ABSTRACT FROM AUTHOR]

This note reports on a novel method for the rapid reduction of graphene oxide (GO) paper using a glow discharge plasma reactor. Glow discharge is produced and sustained between two parallel-plate graphite electrodes at a pressure of 240 mTorr. By exposing GO paper at the junction of negative-glow and Faraday-dark area for 4 min, the oxygen-containing groups can be effectively removed (C/O ratio increases from 2.6 to 7.9), while the material integrality and flexibility are kept well. Electrochemical measurements demonstrate that the as-obtained reduced GO paper can be potentially used for supercapacitor application. [ABSTRACT FROM AUTHOR]

Microscale measurements of halftone dots allow us to investigate the ink transmittance as a function of the position on the halftone dots and to characterize the edges of the halftone dots. In this work, an optical microscope mounted with a commercial camera and a High Dynamic Range (HDR) capture method were combined to measure accurately the printed dots at the microscale. Each stage of the method development has been quantified and compared to simple imaging. On the equipment, the parameters of acquisition have been optimized: size of the observed area under the microscope, exposure time, and fusion of different images resulting from the HDR method. The development of this method allowed comparing three types of printing: offset, inkjet, and electrophotography. The interest of microscopic analysis is to retrieve information that is not accessible at the macroscopic level: descriptors of the ink dot shape and a more precise model of the light diffusion in paper. Furthermore, variables classically measured at the macroscopic level can be assessed: optical densities and colorimetric values. Compared to the single method, the HDR method makes it possible to measure accurately the print characteristics. The coefficient of variation is reduced from 30% to 5%. The perspective of this work is to provide additional information for authenticating printed documents. [ABSTRACT FROM AUTHOR]

Fluxgate sensors are currently widely used for weak magnetic field measurement because of their relatively great performance, such as resolution, power consumption, and measurement of vector magnetic fields directly. Since the analog fluxgate sensor has some drawbacks, e.g., it would be influenced by the noise of the analog circuit. Hence, in recent years, the analog circuit is gradually inclined to be realized by digital processing in which the software parameter adjustment is employed to replace the analog components, which can greatly improve the flexibility of the design. This paper proposes a digital single-axis fluxgate sensor according to the cobalt-based amorphous effect. To be specific, the analog signal output by the fluxgate is sampled directly by an analog-to-digital converter to obtain the signal waveform in digital form after amplification. The demodulation, filtering, and integration of the signal are all solved by mathematical algorithms. Based on the working principle of the fluxgate sensor, the selection of the magnetic core material and coil winding method of the fluxgate sensor probe is introduced in detail. The design and function of the excitation circuit and preamplifier circuit, as well as the specific realization of digital signal processing, are described. Finally, the performance test of the digital fluxgate sensor was performed under laboratory conditions, and the magnetic anomaly detection comparison experiment was performed outdoors with commercial fluxgate sensors. To sum up, the linearity of the digital single-axis fluxgate sensor is better than 1 × 10−5, and the root mean square noise value is below 0.1 nT. At the same time, it has good magnetic field tracking performance and is extremely sensitive to the magnetic field of the measurement area. [ABSTRACT FROM AUTHOR]

In many low-noise applications, extracting information from the extremely noisy signal is required. This task can be accomplished by a lock-in amplifier if the frequency of the signal is known before detection. Error signal output from the physics package of the rubidium atomic clock (RbAC) is one of those noisy signals. A lock-in amplifier extracts the desired information from such a signal as the frequency of the error signal is known beforehand. The Space Applications Centre of the Indian Space Research Organisation is developing the Indian Rubidium Atomic Frequency Standard (IRAFS) for Navigation with Indian Constellation. We have developed a digital lock-in amplifier with a very high-resolution frequency control voltage for IRAFS. This paper demonstrates the digital lock-in amplifier with a novel method of combining two 12-bit digital-to-analog converters (DACs) to get higher resolution 20-bit output for precise frequency control and tuning. This design technique allows a digital lock-in amplifier to be used for high-performance RbAC for space applications as precision DACs with higher resolution are not available in space-qualified versions. [ABSTRACT FROM AUTHOR]

This note reports on a novel method for the rapid reduction of graphene oxide (GO) paper using a glow discharge plasma reactor. Glow discharge is produced and sustained between two parallel-plate graphite electrodes at a pressure of 240 mTorr. By exposing GO paper at the junction of negative-glow and Faraday-dark area for 4 min, the oxygen-containing groups can be effectively removed (C/O ratio increases from 2.6 to 7.9), while the material integrality and flexibility are kept well. Electrochemical measurements demonstrate that the as-obtained reduced GO paper can be potentially used for supercapacitor application.

Paper spray (PS) ionization is a recently developed ion source that has been used to analyze samples in their native environments at ambient pressure without requiring sample preparation or pre-separation. The design of an ion mobility spectrometer (IMS) coupled with PS ionization can help expand IMS applications to on-site detection of complex liquid samples. We report a paper spray ionization ion mobility spectrometer prototype that consists of a PS source and an ion mobility spectrometer optimized using a numerical simulation. The performance of the design was evaluated by measuring 2, 6-di-tert-butylpyridine (2, 6-DtBP). The mobility spectra of the 2, 6-DtBP exhibited a single-product ion peak with reduced mobility calculated at 1.42 cm2/(V s) and a linear response of 0.1-10 μg/ml, with an estimated detection limit of 0.05 μg/ml. The Relative Standard Deviation for 1 μg/ml was 5.7% over 11 measurements. The highest resolving power (47) was measured for 2, 6-DtBP. Based on these preliminary results, the present PSIMS design is expected to become a tool of choice for the rapid analysis of complex liquid samples. [ABSTRACT FROM AUTHOR]

Several deep learning partial discharge (PD) diagnostic approaches have been developed in recent years to guarantee the security and stability of gas-insulated switchgear (GIS). The centralized training method requires multiple clients to jointly obtain as much data as possible to train the model to achieve excellent performance, which is impractical due to conflicts of interest and privacy protection. Furthermore, because of differences in the distribution of client data and the presence of a small sample, achieving high-precision and robust diagnosis for each client is an urgent problem. To that end, a novel personalized federated meta-learning (FML) is proposed in this paper to address the aforementioned issues. It develops reliable and personalized PD diagnosis models by collaborating with multiple clients and solves the problem of small sample diagnosis through scenario training under the premise of protecting data privacy. The experimental results show that the FML proposed can diagnose GIS PD with high precision and robustness for each client while maintaining privacy. The diagnostic accuracy of the FML proposed in this paper, especially for on-site unbalanced small sample clients, is 93.07%, which is significantly higher than that for other methods. It serves as a model for the collaborative development of an effective GIS PD diagnostic model. [ABSTRACT FROM AUTHOR]

The article presents a list of authors from the Joint European Torus-European Fusion Development Agreement that contributed to nineteen papers that were published in the October 2008 issue of "Review of Scientific Instruments," including G. Agarici, M. Airila, and R. Akers.

Hyperspectral imaging (HSI) is a popular method of substance identification and mapping in many fields. Light-emitting diodes (LEDs) can be introduced as an active light source, which have been widely used with the distinct advantages of small size, low energy consumption, long lifetime, and fast switching. In this paper, we propose an active HSI system that is based on a multi-wavelength LED-array light source. This LED-based HSI system has a simple and stable configuration, without the complex dispersive spectrometer and mechanical scanning device. The proposed HSI system has been validated using the standard color checker, showing a reliable spectral performance. Moreover, the spatial-spectral information of Chinese paper-cuttings has been successfully extracted, which indicates the great potential in practical applications. [ABSTRACT FROM AUTHOR]

Develops an instrument for measuring rapid local mass density formation in fibrous network and films using electron beam transmission imaging. Purpose of modifying the electron microscope; Determination of local optical density; Use of single charge coupled device imaging system for the electron and light transmission methods.

Describes the development of a Monte Carlo program to simulate the gas dynamics inside flow reactors, also known as Knudsen cell, specially adapted to study heterogeneous reactions. Application of the Monte Carlo technique to calculate trajectories of individual molecules considering only gas-wall collisions.

Describes a low-pressure flow reactor operated as a Knudsen cell and intended for chemical kinetic studies. Design of the reactor to study heterogeneous reactions; Measurement principle; Details of the low temperature support; Measurement of the water vapor pressure above ice; Reduction of errors and uncertainties.

The combination of large tooling size, environmental vibration, and equipment errors at the aircraft assembly site leads to errors in the enhanced reference system (ERS) point measurement information. ERS point errors directly reduce the accuracy of the assembly measurement field. This paper proposes ERS point error prediction and registration compensation based on the neural network to address this problem. First, the effects of equipment measurement errors and environmental vibration factors on the measurement field are studied. The ERS point error prediction model based on the neural network is established. On this basis, model evaluation is used to assess the prediction model of this paper. Then, a measurement field registration compensation model is constructed based on the neural network error results for ERS point compensation analysis. Finally, an experimental validation platform was built to predict the ERS point errors and compensate for the constructed measurement fields using the method in this paper. The experimental results show that, compared with the conventional method, the maximum registration errors in the X, Y, and Z directions are reduced from 0.0812, −0.0565, and −0.2810 to −0.0184, −0.0010, and 0.0022 mm, respectively, after compensation in this paper. The method proposed in this paper can not only predict the ERS point error state and provide a reference for designers but also guide the selection of appropriate ERS points when constructing the measurement field. The compensation method in this paper effectively reduces the measurement field registration error. [ABSTRACT FROM AUTHOR]

Moisture ingress is one of the major causes of aging in oil–paper insulated transformers; the measurement of the moisture content of the insulating material is thus necessary during transformer disassembly for maintenance. One critical engineering consideration is the need for rapid and nondestructive moisture content measurement of the oil–paper insulation to minimize the power-outage time. Herein, a rapid characterization method for the moisture content of oil–paper insulation based on the dielectric response obtained using a microstrip petal-like ring resonator (MPRR) is proposed. The geometric parameters of the resonator and dielectric response model were established based on simulations and theoretical analysis. The geometry of the resonant ring was optimized by modifying the originally circular ring structure of the microstrip ring resonator (MRR) into a petal-like ring structure; this increases the number of resonant peaks from five to seven in the frequency range of 0.5–6.0 GHz for the same electrode area. The effects of the coupling mode, coupling gap, and microstrip ring size on the resonance characteristics of the MPRR were simulated and analyzed. Compared with the MRR, the MPRR has the advantages of a reduced fundamental resonant frequency and a smaller resonant-ring area that improves radiation efficiency. The impact of moisture content on the dielectric response of the pressboard obtained using the MPRR was studied. A moisture-calculation equation based on the measured dielectric response for a selected type of pressboard was established by the Lasso regression. The results of verification experiments show that the error of the proposed method is sufficient for practical applications. [ABSTRACT FROM AUTHOR]

The temporal interference stimulation is a new technique to modulate brain activity by applying multiple channels of voltage-controlled current source (VCCS) simultaneously to the receptor surface. In this paper, the envelopes of the overlapped current waves at several areas of the receptor were analyzed and discussed with different circuit structures of VCCS. A complementary differential current source (CDCS) was designed to fit the best circuit topology based on the analysis of the enhanced Howland current source structure. Experiments were conducted by injecting current to a swine tissue using the CDCS and conventional VCCS and acquiring the voltage waveform data from different parts of the tissue. The waveforms were compared and analyzed, revealing that the conventional VCCS may generate an interference envelope in unexpected regions, while the CDCS did not. The CDCS design approach in this paper provides a new solution for temporal interference stimulation VCCS. [ABSTRACT FROM AUTHOR]

To meet the high requirements for positioning accuracy and multiple dimensions of positioning systems in the fields of precision measurement and precision machining, a new submicron-precision three-dimensional (3D) low cross-interference positioning system is designed and fabricated in this paper. The 3D motion stage mainly includes a mechanical structure, a support and guide system, and a driving system. The Abbe offset error is eliminated by adopting a coplanar structure in the X and Y directions, thus minimizing the mutual cross-interference of the motion stage. The X and Y motion stages are driven by a ball screw pair and an alternating current servo motor, which are supported and guided by an air-floating rail and slider. Moreover, the X and Y air-floating stages adopt a lateral structure and double rails, respectively. The Z-motion stage is directly driven by a high-precision piezoelectric motor. In addition, the system achieves high-precision motion by using the dual-loop control technology of secondary feedback combined with the high-resolution control characteristics of the servo motor. The performance of the positioning system is evaluated through a series of verification experiments. Results show that the stroke of the positioning system of the 3D air-floating motion stage can reach 100 × 100 × 100 mm3, and the repeated positioning accuracy is better than 0.41 μm (k = 2, k is defined by the International Organization for Standardization as the coverage factor). The maximum cross-interference of the X-stage is 180 nm, and the Y-stage reaches 320 nm when running with a full stroke of 100 mm in the Z-direction, demonstrating good repeatability, stable running, and high straightness. The submicron-precision 3D air-floating motion stage developed in this paper can be used as a suitable solution for coordinate measuring machines, microlithography, and micromachining applications when combined with an additional nanoprecision microstage. [ABSTRACT FROM AUTHOR]

This paper introduces the design and implementation of a prototype Digital Delay Generator (DDG) characterized by high precision, low jitter, and a wide delay range, fully realized within a Field Programmable Gate Array (FPGA). The DDG's architecture is based on an innovative combination of an embedded time-to-digital converter (TDC) and Multi-stage Time Interpolation (MTI) delay logic. The paper explores the factors influencing delay jitter during external trigger mode and carefully selects the optimal design approach for each element. The embedded TDC, which undergoes automatic calibration, accurately measures the time difference between the arrival of an external trigger and the FPGA's internal clock signal. When paired with the MTI delay logic, this allows for highly precise control over delay durations. A key aspect of this design is its sole dependence on the FPGA's built-in resources, ensuring simplicity in implementation and adaptability to various applications. Evaluation of the prototype has shown promising results, demonstrating a delay resolution as fine as 20 ps and maintaining a low jitter of 105 ps peak-to-peak (20 ps rms) when operated in the externally triggered mode. [ABSTRACT FROM AUTHOR]

This paper proposes a two-dimensional calibration method for resolving the nano-positioner pedestal micro-deformation crosstalk errors during the auction process. This refinement aims to enhance the nano-positioner's accuracy and reduce coupling crosstalk errors. The reaction force exerted by the piezoelectric actuator can cause micro-deformation in the nano-positioner sensor pedestal, causing substantial errors in uncalibrated closed-loop control. This phenomenon has been previously overlooked. According to the two-degree of freedom parallel-symmetric decoupled nano-positioner deformation characteristics, a two-dimensional calibration matrix is proposed to suppress the crosstalk between two axes caused by the micro-deformation of the sensor pedestal. Experimental results show that the calibrated closed-loop system reduces X-axis and Y-axis coupling crosstalk errors to 1/67th and 1/18th of the uncalibrated closed-loop system, respectively, concurrently enhancing the positioning accuracy to 11.8 and 17 times that of the uncalibrated closed-loop system. The calibrated closed-loop feedback control method proposed in this paper proves effective for all compact nano-positioners with pedestal deformation issues. This research provides a crucial reference for the design of nano-positioners, offering insights into enhancing their accuracy and mitigating crosstalk issues. [ABSTRACT FROM AUTHOR]

Percutaneous coronary intervention (PCI) has become a vital treatment approach for coronary artery disease, but the clinical data of PCI cannot be directly utilized due to its unstructured characteristics. The existing clinical named entity recognition (CNER) has been used to identify specific entities such as body parts, drugs, and diseases, but its specific potential in PCI clinical texts remains largely unexplored. How to effectively use CNER to deeply mine the information in the existing PCI clinical records is worth studying. In this paper, a total of 24 267 corpora are collected from the Cardiovascular Disease Treatment Center of the People's Hospital of Liaoning Province in China. We select three types of clinical record texts of fine-grained PCI surgical information, from which 5.8% of representative surgical records of PCI patients are selected as datasets for labeling. To fully utilize global information and multi-level semantic features, we design a novel character-level vector embedding method and further propose a new hybrid model based on it. Based on the classic Bidirectional Long Short-Term Memory Network (BiLSTM), the model further integrates Convolutional Neural Networks (CNNs) and Bidirectional Encoder Representations from Transformers (BERTs) for feature extraction and representation, and finally uses Conditional Random Field (CRF) for decoding and predicting label sequences. This hybrid model is referred to as BCC-BiLSTM in this paper. In order to verify the performance of the proposed hybrid model for extracting PCI surgical information, we simultaneously compare both representative traditional and intelligent methods. Under the same circumstances, compared with other intelligent methods, the BCC-BiLSTM proposed in this paper reduces the word vector dimension by 15%, and the F1 score reaches 86.2% in named entity recognition of PCI clinical texts, which is 26.4% higher than that of HMM. The improvement is 1.2% higher than BiLSTM + CRF and 0.7% higher than the most popular BERT + BiLSTM + CRF. Compared with the representative models, the hybrid model has better performance and can achieve optimal results faster in the model training process, so it has good clinical application prospects. [ABSTRACT FROM AUTHOR]

Ferrite-loaded gyromagnetic nonlinear transmission line (GNLTL) provides a possible option to compress an input pulse to a narrower width for its remarkable sharpening effect. However, it is difficult to accurately predict the output of the GNLTL due to the complex interaction between the magnetic moment of ferrite and the bias magnetic field. In this paper, a finite element model of the GNLTL is established based on the Landau–Lifshitz–Gilbert equation to investigate the performance of the GNLTL. To validate this model, a prototype is used for experimental comparison. The result demonstrates good agreement between experiment and simulation. This paper further explores the influence of the bias magnetic field and the length of the GNLTL on the output pulse. Moreover, a method to sharpen the falling edge is proposed based on the reflection and superposition of the GNLTL output. Simulation and experimental results show its effectiveness and feasibility. [ABSTRACT FROM AUTHOR]

The core of electrostatic tomography (EST) is to solve the inverse problem, but the EST independent measurement data are much smaller than the value that needs to be reconstructed, resulting in a more serious inverse problem. This paper presents an improved ResNet-34 network (P-ResNet), which consists of an input layer, a residual feature extraction layer, and an output layer. The number of residual blocks is 3, 4, 4, and 3. After the second convolution in the main path of each residual block, a ReLU activation function is added to enhance the nonlinear expression ability of the network, and the generalization ability of the model is improved by introducing the L2 regularization loss function. A total of 15 930 sets of samples were simulated for the simulation test. After 200 rounds of iteration, the reconstruction results show that the network achieves high accuracy in EST image reconstruction tasks. In addition, the model is tested under different degrees of Gaussian white noise to verify its anti-noise ability. Compared with the traditional algorithms, the image correlation coefficients of this proposed model network are higher. In addition, this paper designs a small sensor to obtain the induced charge values through the principle of electrostatic induction. The reconstructed results obtained from the experimental data are consistent with the simulation results, which verifies the effectiveness and generalization ability of the proposed model. [ABSTRACT FROM AUTHOR]

Multiple monochromatic x-ray imaging (MMI) is a technique for diagnosing the emission spectra of tracer elements in laser-driven inertial confinement fusion experiments. This study proposes an MMI method that combines a simple pinhole array with a laterally graded multilayer mirror. The method directly obtains multiple monochromatic x-ray images by regulating the multilayer thickness in different mirror positions to compensate for the energy-broadening effect. This paper presents a comprehensive design scheme, the multilayer fabrication and experimental verification of the gradient MMI imaging performance. The experimental results show that the method achieves monochromatic imaging with a spectral resolution of ∼70–90 eV in several keV energy regions. This paper presents a practical diagnostic approach for directly and synchronously capturing the spatial, temporal, and spectral information of laser plasma x rays. [ABSTRACT FROM AUTHOR]

Periodically tunable nano-gratings have an irreplaceable role in spectral scanning and optical communication, but the performance of gratings manufactured from different materials varies considerably, and the development of superior materials has energized the preparation of high-precision devices. This paper presents a nanoscale preparation process based on Norland Optical Adhesive 73 (NOA73), which enables the rapid preparation of periodically tunable nano-gratings with up to 100% light transmission. The powerful fluidity and shear rate of NOA73 make it uniquely suited to the preparation of precision devices, allowing the production of up to dense grating structures and offering the possibility of making nanoscale gratings. This paper uses multi-angle hierarchical lithography, die stretching, and replication to achieve further improvements in accuracy and successfully prepare gratings with a period of 500 nm. The successful preparation of NOA73 nano-gratings demonstrates the practicality of NOA73 as a material for precision device fabrication. [ABSTRACT FROM AUTHOR]

In this paper, the event-triggered dynamic output feedback H∞ controller for a discrete-time switched linear system is addressed. The switching of subsystems during the inter-event interval has always been the focus of researchers' discussions. Particularly, multiple switching is allowed to happen during an inter-event interval in this paper. To reflect the characteristics of multiple switching during an inter-event interval, the average dwell time approach is adopted in stability analysis and l2-gain performance analysis. Since the full information of system states cannot always be acquired directly, the dynamic output feedback control is taken into consideration. Furthermore, by utilizing a controller-mode-dependent Lyapunov function, we obtain criteria of global exponential l2 stability for switched systems, which are the basis of controller design. Finally, we provide a numerical example to prove the validity of the theorem proposed in this paper. [ABSTRACT FROM AUTHOR]

Due to the inherent material characteristics of fireworks and negligent safety management, safety accidents have occurred in recent years, resulting in significant personal and property losses. Therefore, the status inspection of fireworks and other energy-containing materials is a hot issue in the field of energy-containing materials production, storage, transportation, and application. The dielectric constant is a parameter used to characterize the interaction between materials and electromagnetic waves. The methods of obtaining this parameter in the microwave band are not only numerous but also fast and easy. Thus, the real-time status of energy-containing materials can be monitored by monitoring their dielectric properties. Usually, temperature variation has an important effect on the state of energy-containing materials, and the accumulation of temperature can directly cause energy-containing materials to burn or even explode. Based on the above background, this paper proposes a method for testing the dielectric properties of energy-containing materials under variable temperature conditions based on the resonant cavity perturbation theory, which provides important theoretical support for testing the state of energy-containing materials under variable temperatures. Based on the constructed test system, the law of the variation of the dielectric constant of black powder with temperature was obtained, and the theoretical analysis of the test results was carried out. Experimental results show that the temperature change will induce chemical changes in the black powder material, specifically in its dielectric properties, and the magnitude of the changes is large, which is very conducive to real-time monitoring of the black powder state. The system and method developed in this paper can be used to obtain the high-temperature evolution of the dielectric properties of other types of energy-containing materials and provide technical support for the safe production, storage, and application of various types of energy-containing materials. [ABSTRACT FROM AUTHOR]

In this paper, a piezoelectric electromagnetic composite energy harvester is studied. The device consists of a mechanical spring, upper and lower base, magnet coil, etc. The upper and lower bases are connected by struts and mechanical springs and secured by end caps. The device moves up and down under the vibration of the external environment. As the upper base moves downward, the circular excitation magnet moves downward, and the piezoelectric magnet is deformed under a non-contact magnetic force. Traditional energy harvesters have the problems of a single form of power generation and inefficient energy collection. This paper proposes a piezoelectric electromagnetic composite energy harvester to improve energy efficiency. Through theoretical analysis, the power generation trends of rectangular, circular, and electric coils are obtained. Simulation analysis yields the maximum displacement of the rectangular and circular piezoelectric sheets. The device uses piezoelectric power generation and electromagnetic power generation to achieve compound power generation, improve the output voltage and output power, and can provide power supply to more electronic components. By introducing the nonlinear magnetic action, the mechanical collision and wear of the piezoelectric elements during the work are avoided, so that the service life and service life of the equipment is extended. The experimental results show that the highest output voltage of the device is 13.28 V when the circular magnets mutually repel rectangular mass magnets and the tip magnet of the piezoelectric element is 0.6 mm from the sleeve. The external resistance is 1000 Ω, and the maximum power output of the device is 5.5 mW. [ABSTRACT FROM AUTHOR]

High-precision accelerometers play an important role in satellite gravity field missions to measure the non-conservative forces acting on the satellites. To map the Earth's gravity field, the accelerometer data must be time-tagged using the on-board global navigation satellite system time reference. For example, in the Gravity Recovery and Climate Experiment mission, the time-tag error of the accelerometers must be within 0.1 ms with respect to the satellite clock. To realize this requirement, the time delay between the actual measurement time and the nominal time of the accelerometer should be considered and corrected. This paper presents the techniques for measuring the absolute time delay of an electrostatic accelerometer on the ground, where this delay is mainly introduced by the low-noise scientific data read-out system, which is based on a Σ–Δ (sigma–delta) analog-to-digital converter (ADC). First, the time-delay sources of the system are theoretically analyzed. Then, a time-delay measurement method is proposed, and its principle and system error are presented. Finally, a prototype is built to demonstrate and investigate the feasibility of the method. Experimental results show that the absolute time delay of the read-out system is 150.80 ± 0.04 ms. This important value is the basis for the final time-tag error correction of the scientific accelerometer data. Meanwhile, the time-delay measurement method described in this paper is also useful for other data acquisition systems. [ABSTRACT FROM AUTHOR]

Thermal sensitive paper has been used as a diagnostic for an intense relativistic electron beam propagating in a rippled magnetic field. The E(r)xB(z) rotation of the beam has been measured from the exposed pattern on the thermal paper and used to calculate the electrostatic field of the beam E(r), and the corresponding values of electron density and beam current. Exposed strips of thermal paper show longitudinal modulation of the radial electron velocity with a period corresponding to that of a rippled magnetic field; modulation of the radial electron velocity at the cyclotron frequency has also been observed.

In this paper, a novel design concept for roll-to-roll printing equipment used for manufacturing printed electronic devices by multi-layer printing is presented. The roll-to-roll printing system mainly consists of printing units for patterning the circuits, tension control components such as feeders, dancers, load cells, register measurement and control units, and the drying units. It has three printing units which allow switching among the gravure, gravure-offset, and flexo printing methods by changing the web path and the placements of the cylinders. Therefore, depending on the application devices and the corresponding inks used, each printing unit can be easily adjusted to the required printing method. The appropriate printing method can be chosen depending on the desired printing properties such as thickness, roughness, and printing quality. To provide an example of the application of the designed printing equipment, we present the results of printing tests showing the variations in the printing properties of the ink for different printing methods. [ABSTRACT FROM AUTHOR]

Magnetorheological fluid (MRF) is a widely used smart material that suffers from sedimentation. Since sedimentation is unavoidable, it is crucial to study and improve the redispersibility of MRFs. However, previous redispersibility testing methods have problems, such as complicated operation and low precision. Simultaneously, a simple and effective method is urgently needed for high-precision modeling of MRF sedimentation to test the rheological properties of settled MRFs at different depths. After systematically analyzing the redispersion problem, this paper proposes decoupling the energy required for redispersing settled MRFs into two parts, which are related to different factors. These two parts are the energy required to separate the agglomerated particles (related to the MRF formula) and that to redisperse the settled MRF uniformly vertically against gravity (related to the solid concentration and packing limit). The energy that separates the agglomerated particles is proportional to the shear stress of slowly shearing the corresponding agglomerated samples, i.e., the yield stress. Thus, this paper proposes a simple microdamage quasi-static indentation method to measure the yield stresses of settled MRFs at different depths to characterize the redispersibility of the corresponding MRFs. Herein, this method is applied to study the mechanisms of the influences of surfactants, thixotropic agents, and their networks on the redispersibility of MRFs. The results indicate that a well-dispersed plate-like thixotropic agent network can effectively improve redispersibility, while surfactants with poor compatibility degrade redispersibility. In summary, this redispersibility test method will greatly facilitate studies of MRFs, such as optimizing the formulas and establishing sedimentation models. [ABSTRACT FROM AUTHOR]

This paper describes a technique for temperature sensitivity or thermal sag measurements of a geometric anti-spring based microelectromechanical system (MEMS) gravimeter (Wee-g). The Wee-g MEMS gravimeter is currently fabricated on a (100) silicon wafer using standard micro-nano fabrication techniques. The thermal behavior of silicon indicates that the Young's modulus of silicon decreases with increase in temperature (∼64 ppm/K). This leads to a softening of the silicon material, resulting in the proof mass displacing (or sagging) under the influence of increasing temperature. It results in a change in the measured gravity, which is expressed as temperature sensitivity in terms of change in gravity per degree temperature. The temperature sensitivity for the silicon based MEMS gravimeter is found to be 60.14–64.87, 61.76, and 62.76 µGal/mK for experimental, finite element analysis (FEA) simulation, and analytical calculations, respectively. It suggests that the gravimeter's temperature sensitivity is dependent on the material properties used to fabricate the MEMS devices. In this paper, the experimental measurements of thermal sag are presented along with analytical calculations and simulations of the effect using FEA. The bespoke optical measurement system to quantify the thermal sag is also described. The results presented are an essential step toward the development of temperature insensitive MEMS gravimeters. [ABSTRACT FROM AUTHOR]

The power transformer is the core equipment of the power system, a sudden failure of which will seriously endanger the safety of the power system. In recent years, artificial intelligence techniques have been applied to the dissolved gas analysis evaluation of power transformers to improve the accuracy and efficiency of power transformer fault diagnosis. However, most of the artificial intelligence techniques are data-driven algorithms whose performance decreases when the data are limited or significantly imbalanced. In this paper, we propose an active learning framework for power transformer dissolved gas analysis, in which the model can be dynamically trained based on the characteristics of the data and the training process. In addition, this paper also improves the original active learning spatial search strategy and uses the product of sample feature differences instead of the original sum of differences as a measure of sample difference. Compared to passive learning algorithms, the novel approach could significantly reduce the data labeling effort while improving prediction accuracy. [ABSTRACT FROM AUTHOR]

Brain–computer interface (BCI) technology based on P300 signals has a broad application prospect in the assessment and diagnosis of clinical diseases and game control. The paper of selecting key electrodes to realize a wearable intention recognition system has become a hotspot for scholars at home and abroad. In this paper, based on the rich-club phenomenon that exists in the process of intention generation, a phase lag index (PLI)-rich-club-based intention recognition method for P300 is proposed. The rich-club structure is a network consisting of electrodes that are highly connected with other electrodes in the process of P300 generation. To construct the rich-club network, this paper uses PLI to construct the brain functional network, calculates rich-club coefficients of the network in the range of k degrees, initially identifies rich-club nodes based on the feature of node degree, and then performs a descending order of betweenness centrality and identifies the nodes with larger betweenness centrality as the specific rich-club nodes, extracts the non-linear features and frequency domain features of Rich-club nodes, and finally uses support vector machine for classification. The experimental results show that the range of rich-club coefficients is smaller with intent compared to that without intent. Validation was performed on the BCI Competition III dataset by reducing the number of channels to 17 and 16 for subject A and subject B, with recognition quasi-departure rates of 96.93% and 94.93%, respectively, and on the BCI Competition II dataset by reducing the number of channels to 17 for subjects, with a recognition accuracy of 95.50%. [ABSTRACT FROM AUTHOR]

Piezoelectric actuators commonly used in microgrippers have a small stroke, and their accuracy is reduced by the transmission amplification unit, which leads to a contradiction between the clamping range and the clamping accuracy in existing piezoelectric-actuated microgrippers. This paper proposes a design scheme to divide the total clamping range of the microgripper into segments based on the compliant multistable mechanism (CMM). First, by using the stable equilibrium positions of the CMM, the total clamping range of the microgripper is divided into multiple smaller clamping sub-intervals to accommodate objects of different scales. Then, the theoretical models of the displacement amplification ratio of the microgripper amplification mechanism and the stiffness of the microgripper in different clamping sub-intervals are established, and the force-displacement characteristics of the CMM are analyzed. Next, through finite element simulation, the correctness of the theoretical analyses is verified, and it is shown that objects between 0 µm and 1.650 mm can be clamped using four clamping sub-intervals under a five times displacement amplification ratio. Finally, a microgripper of the CMM consisting of two three-segment fully compliant bistable mechanisms connected in series is designed and machined, and microgripper segmented clamping experiments are conducted. The experimental results demonstrate the feasibility of the design scheme proposed in this paper. [ABSTRACT FROM AUTHOR]

Riveting quality is crucial to an aircraft's overall aerodynamic performance and fatigue life. In order to effectively extract the point cloud of rivet heads and analyze the quality of riveting, this paper proposes a rivet flushness detection method based on the normal vector-density clustering algorithm. First, initial point cloud data sampling is based on normal vectors. Then, the density clustering algorithm is employed to cluster and extract the point cloud of rivet heads. Subsequently, the obtained point cloud of rivet heads is subjected to the random sample consensus algorithm for fitting the contour and obtaining the model parameters of the rivet head. The paper introduces a quality detection metric to describe the flushness of the rivet head. Finally, the proposed method is applied to analyze the skin and theoretical model point cloud data of rivets. The results demonstrate that the proposed method yields small errors and high accuracy compared to theoretical values. The method is further employed for quality detection and analysis of rivet flushness in practical aircraft engineering. A visualization system for rivet flushness quality detection is developed to represent the results visually. This system enhances the intuitive identification of rivet detection outcomes. Therefore, the proposed method holds significant engineering application value in rivet flushness detection. [ABSTRACT FROM AUTHOR]

Industrial robots are important components in the production and manufacturing industry. As a core component of the industrial robot, the industrial robot reducer plays a crucial role in the performance of the entire industrial robot. The error analysis and accuracy traceability of the industrial robot reducer testing instrument are of great significance in improving the quality of the precision reducer. Therefore, it is essential to calibrate the dynamic torsional moment measurement error of the instrument. The features of the dynamic torsional moment measurement error are analyzed in this paper. Based on these features, a new dynamic torsional moment measurement error calibration method is proposed based on the Bisquare curve fitting–improved Bayes particle swarm optimization–nonlinear echo state network (BCF–IBPSO–NESN) algorithm. The proposed method focuses on calibrating the dynamic torsional moment measurement error of the industrial robot reducers in real time. The experimental results show that the dynamic torsional moment measurement error of the input side torsional moment measurement module and the output side torsional moment measurement module can be reduced to ±0.05 Nm and ±1 Nm, respectively. The contribution of this paper is that the method calibrates the dynamic torsional moment measurement error. It supplies a guideline for calibrating the dynamic torsional moment measurement error of the instrument under any load. [ABSTRACT FROM AUTHOR]

© 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A streaked radiography diagnostic has been proposed as a technique to determine the ablator mass remaining in an inertial confinement fusion ignition capsule at peak velocity. This instrument, the “HXRI-5,” has been designed to fit within a National Ignition Facility Diagnostic Instrument Manipulator. The HXRI-5 will be built at Sandia National Laboratories (SNL), and initial testing will be done at the SNL Z-Beamlet Facility. In this paper, we will describe the National Ignition Campaign requirements for this diagnostic, the instrument design, and the planned test experiments. [ABSTRACT FROM AUTHOR]

In this paper, a novel ultra-high timing resolution pulse generator is proposed. It is based on the waveform real-time computation method. Through real-time computing and filtering of the waveform samples, a pulse with a 0.1 ps timing resolution pulse could be generated at a 2.5 GSPS sampling rate. Based on the waveform real-time computation method, jitters are injected into the waveform time parameter to break the harmonic components caused by non-integer multiples of the sampling rate and waveform frequency. Waveform spurs are further suppressed using this approach. The pulse error correction is achieved by designing digital filters that complement the waveform distortion features. The complementary digital filters are then combined as Farrow filter coefficients by polynomial fitting. Based on the real-time computation method, pulse width modulation, frequency modulation, and amplitude modulation are easy to realize. The implemented pulse generator has four channels, whose minimum pulse width, edge time, frequency range, and amplitude range are 4, 2.5 ns, 1 μHz–120 MHz, and 50 mVpp–5 Vpp, respectively. All timing resolution and timing accuracy of pulse width, edge time, pulse period, and channel delay are 0.1 and 50 ps, respectively. Timing parameters can be changed continuously without glitches. [ABSTRACT FROM AUTHOR]