Rising Edge Research Articles

42 mm large aperture variable-focus lens based on the liquid-membrane-liquid structure

Variable-focus lenses enable dynamic focus control and reduce the volume of the optical systems. However, few of them have been scaled up to large apertures of 10 mm, which limits their application scenarios. Here, a variable-focus lens prototype with a 42 mm large aperture based on the liquid-membrane-liquid structure was proposed and evaluated. The prototype shows a range of adjustable optical power at [−3 D, +3 D], and demonstrates high repeatability during the operation process. The average normalized modulation transfer function value for an imaging system shows 0.7904 in 17.204 lp/mm and 0.5439 in 34.409 lp/mm. The resolution values in horizontal and vertical directions are 8 lp/mm and 8.98 lp/mm, respectively. Besides, the millisecond-level response time of the prototype is achieved with a rising edge of 5.02 ms and a falling edge of 3.66 ms. The prototype demonstrates the application scenarios of variable-focus lenses for large aperture requirements with the potential for satisfactory performance, such as in wearable devices, machine vision systems, and so on.

Reversed self-steepening in Si3N4-organic hybrid slot waveguides with engineered nonlinearity

Abstract Dispersion of nonlinearity greatly influences both temporal and spectral evolutions for ultrashort pulses, although difficult to be tailored in a wide spectral range. Here, we show the hardly observable reversed self-steepening in an on-chip Si3N4-organic hybrid slot waveguide with sophisticated dispersion and an increased nonlinear coefficient with wavelength. An octave-spanning supercontinuum with significant red-shift spectral broadening and a rectangle-shaped pulse waveform with a sharp rising edge of 13 fs can be generated. We study the robustness of reversed self-steepening under different operating conditions and reveal its nonlinear dynamics. This deepens the understanding on the dispersion of nonlinearity and helps develop novel nonlinearity-engineered devices for on-chip optical shock formation, pulse shaping, and signal processing in the future.

Relevance of the Iron Distribution in Natural Smectite Clays for the Thermal Stability of PMMA-Clay Nanocomposites.

Polymer-clay nanocomposites have greater thermal stability compared to the pristine polymer matrix. This can be attributed to the physical barrier provided by the inclusion of 2D clay nanoparticles (especially of the smectite group), together with radical trapping related to the distribution of specific 3d atoms in the inorganic phase. To elucidate the relevance of the Fe3+ distribution in this synergic effect, the iron atoms present in octahedral sheets of natural nontronite clay (Non, 5.6 wt % Fe) or in maghemite (M) nanoparticles (γ-Fe2O3) were incorporated in a poly(methyl methacrylate) (PMMA) matrix. Na-laponite (Lap) clay was used to evaluate the contribution of the diffusion barrier effect to the increased thermal stability of a PMMA-Lap nanocomposite, as evidenced by the upshift of the thermogravimetric (TGA) curve compared to that for PMMA. The contribution of radical trapping to the thermal stability of the PMMA-Non nanocomposite was evidenced by a significant shift of the Fe K-edge rising edge position by -4.5 eV after iron reduction by heating in N2, while similar treatment of pristine nontronite did not lead to a significant rising edge shift in the X-ray absorption spectra (XAS). This downshift demonstrated the reduction of Fe3+ to Fe0, induced by the sequestration of radicals formed by PMMA depolymerization. Raman spectroscopy analysis evidenced the formation of graphitic char deposits above 400 °C, further improving the thermal stability of PMMA-Non by providing an additional physical barrier to mass transport. A fourth contribution of well-dispersed iron was the abstraction of carbon from the char by the iron carburization reaction, which hindered CO2 formation by oxidative coking. In contrast, no relevant contribution of graphitic layer deposition was observed for the PMMA-M-Lap nanocomposite, where its improved thermal stability was only due to the combined contributions of the gas diffusion barrier effect and radical trapping by iron atoms. The maghemite effectively captured the radicals confined by the clay sheets, resulting in significant stabilization of the nanocomposite, with a shift of the mass loss of the PMMA-M-Lap nanocomposite compared to PMMA-Lap.

Epitaxial growth of c-axis inclined Sr3YCo4O10.5+ δ thin film: Insights into laser-induced voltage signals arising from magnetic anisotropy

We report the laser-induced voltage (LIV) signals in cubic phase Sr3YCo4O10.5+δ (CP-SYCO) thin films with a c-axis tilted and discuss the relationship between the LIV signals and magnetic anisotropy. CP-SYCO thin films were epitaxially deposited on 0°, 5°, 10°, 15°, and 20° miscut LaAlO3 (001) substrates using pulsed laser deposition (laser energy of 200 mJ, post-annealed at 760 °C). The peak voltage of the LIV for the 15° tilted CP-SYCO film is 310 mV (under laser energy of 400 mJ/pulse), with a rising edge of 26 ns. Compared with G-type antiferromagnetic ordered tetragonal phase Sr3YCo4O10.5+δ(OT-SYCO, deposited at a laser energy of 300 mJ, post-annealed at 790 °C) film, the CP-SYCO exhibits much stronger magnetization anisotropy along in-plane and out-plane due to the possible A-type antiferromagnetic moment arrangement. CP-SYCO films also demonstrate significant thermoelectric anisotropy, supporting the transverse thermoelectric effect, which is partially attributed to the contribution of spin entropy. This study provides an understanding of the anisotropic behavior in atomic layer thermoelectric stack materials and explores magnetic anisotropic material systems.

High‐Speed and Low‐Power 2 × 2 Thermo‐Optic Switch Based on Dual Silicon Topological Nanobeam Cavities

AbstractA 2 × 2 thermo‐optic (TO) switch using dual topological photonic crystal nanobeam (PCN) cavities on the silicon‐on‐insulator (SOI) platform is proposed and experimentally demonstrated. A Fano resonance is observed due to the interference between the topological interface state of the 1D topological PCN cavity and the Fabry‐Perot (F‐P) cavity mode formed between the two facets of the finitely long nanobeam waveguide. Thanks to the sharp rising edge of the spectral response of the Fano resonance and the high confinement of light in the topological PCN cavities, a 2 × 2 TO switch is realized with short switching time and low power consumption. The measured switching power is only 1.55 mW, and the rising time and the falling time are 3 and 5.6 µs, respectively in the on‐off switching experiments. To the best of the knowledge, this is the first time that a dual topological PCN structure is utilized to realize a high‐speed and low‐power TO switch, revealing the possibility of designing high‐performance reconfigurable optical devices and networks using topological photonics.

Research on Electromagnetic Environment Characteristic Acquisition System for Industrial Chips

With the system interconnection and intelligence of application scenario equipment, the electromagnetic environment of chips is becoming more and more complex. Problems such as communication interruption and data loss caused by electromagnetic interference often occur. The electromagnetic reliability of chips has become an important index to measure their availability. In order to effectively detect the electromagnetic reliability of industrial chips applied to specific scenarios, it is necessary to measure and analyze the electromagnetic characteristics of the application scenarios, as the boundary conditions of the electromagnetic protection simulation analysis and design of the chip, and to develop Electromagnetic Compatibility (EMC) test items, test limits and test methods suitable for carrying out tests and monitoring on chips. The paper presents an acquisition system, which can complete the collection of transient electromagnetic interference, steady electromagnetic field, temperature, humidity and near-field data. The transient interference measurement frequency range is 300 kHz–500 MHz, with a rising edge of 1.5 ns; the steady-state electromagnetic field measurement frequency ranges from 100 Hz to 3 GHz. By collecting the electromagnetic environmental characteristics of chips and analyzing situations in which chips are prone to interference, protective measures can be implemented.

관상동맥 CT 조영 검사 시, 초 고해상도 딥러닝 알고리즘이 적용된 스텐트 영상의 진단적 가치

Recently, with the advancement of artificial intelligence image reconstruction technology, we are attempting to evaluate the accuracy of coronary artery stent lumen by developing ultra-high-resolution deep learning image reconstruction technology based on the most accurate 0.25mm multi-detector available. This study was divided into patient studies and phantom studies. Images were reconstructed in the same patient using four different methods: filter correction reverse projection, repetitive reconstruction, deep learning reconstruction, and artificial intelligence ultra-high resolution reconstruction. To objectively evaluate image quality, four parameters, image noise, CT density, signal-to-noise ratio, and contrast-to-noise ratio, were analyzed for each dataset. The phantom study installed a latex Nelaton sterilized catheter to express the coronary artery in the dummy chest phantom. Subsequently, a coronary stent (2.5mm and 3.5mm in diameter) was inserted into each catheter. Images were obtained using various reconstruction techniques (FBP, IR, DLR, and UHR-DLR) for each CT manufacturer. Stent clarity was evaluated using edge rise distance (ERD) and edge rise slope (ERS). We showed that the average Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) of coronary arteries reconstructed with Ultra-High Resolution Deep Learning Reconstruction (UHR-DLR) improved by 29.2% and 36.4% compared to those reconstructed with DLR, respectively. Image noise was reduced by about 21.4% in UHR-DLR. The ERS average value of the coronary stent phantom measured by the CT manufacturers was highest in the UHR-DLR of Aquilion ONE Prism (Canon), and the ERD value is statistically significant for each CT manufacturer. Compared to FBP, HIR, and DLR, UHR-DLR not only improved image clarity and reduced image noise and blooming artifacts but also clearly showed the stent support structure and stent lumen.

Novel level and edge-triggered universal shift registers with low latency in QCA technology

Shift registers are one of the main blocks in processors. In this paper, two new universal shift registers are designed based on Quantum-Dot Cellular Automata (QCA) nanotechnology. Both of the proposed level triggered and edge triggered universal shift register in QCA technology shows good performance in regards of the number of cells, occupied area, delay, and power. These designs also have reset abilities. Simulations show that the proposed 4-bit level triggered universal shift register with reset ability has 1057 QCA cells, 1.27 μm2 occupied area, and delay of about three cycles of QCA clock. In addition, the proposed rising edge triggered 4-bit universal shift register with reset ability has 1085 QCA cells, 1.27 μm2 occupied area, and delay of about three cycles of QCA clocks.

Machine learning-based discrimination of bulk and surface events of germanium detectors for light dark matter detection

Surface events that exhibit incomplete charge collection are an essential background source in the light dark matter detection experiments with p-type point-contact germanium detectors. We propose a machine learning-based algorithm to identify bulk and surface events according to their pulse shape features. We construct the training and test set with part of the γ-source calibration data and use the rising edge of the waveform as the model input. This method is verified with the test set and another part of the γ-source calibration data. Results show that this method performs well on both datasets, and presents robustness against the bulk events’ proportion and the dataset size. Compared with the previous approach, the uncertainty is reduced by 16% near the energy threshold on the physics data of CDEX-1B. In addition, the key pattern identified in the waveform is verified to be consistent with its physical nature by digging into this algorithm.

Pulse area compensation approach for ballistic deficits correction in perovskite CsPbBr3 semiconductor detector

Halide perovskite CsPbBr3 semiconductor has exhibited extraordinary performance on ionizing radiation detection at room temperature in the light of excellent photoelectric properties. However, signals from the CsPbBr3 planar detector usually comprises the long rising edge due to its low hole carrier mobility, subsequently leading to severe ballistic deficits in pulse amplitudes (over 10 %) when the shaping time is inferior to rise time. To overcome this issue, the integrated pulse area approach is proposed and implemented herein to compensate the amplitudes underestimation of pulses particularly with varied rise times. It was verified that the pulse area extracted by this approach was insensitive to the rise time (when varying from 1 to 130 μs) while manifesting the relative variance below 1.49 × 10−5. Accordingly, the bivariate distribution between the integrated pulse area and rise time regarded as unaffected by ballistic deficits was finally accomplished which reflected the actual depth of individual event interactions. The approach is computationally feasible in eliminating the ballistic deficit, and is anticipated to foster the deployment of perovskite detector in radiation detection.

GENERATION OF RECTANGULAR NANOSECOND ELECTROMAGNETIC PULSES WITH A PICOSECONDS RISE FRONT

A method for generation of ultra-wideband electromagnetic pulses with a nanosecond duration and a picosecond rise time has been studied. The emitter is a horn antenna with a photoconductive switch irradiated by laser pulses. It has been shown that the duration of ultra-wideband electromagnetic pulses is determined by the length of the antenna and the semiconductor material, and the rising front is determined by the front of the laser pulses used to initiate the photoconductive switch. The work shows typical pulse durations of ~1 ns with a rising edge of up to ~34 ps.

An 8 bit-ENOB Sampling-rate Reconfigurable Asynchronous SAR ADC with Metastability Watchdog Circuit for Activity-driven Multi-Channel CMOS Readout ASICs for Space Applications

This article presents an innovative architecture and design of an 8-bits Effective-Number-of-Bits (ENOB) Asynchronous Successive-Approximation-Register (ASAR) Analog-to-Digital-Converter (ADC), aiming at activity-driven multi-channel Complementary-Metal-Oxide-Semiconductor (CMOS) readout Application-Specific-Integrated-Circuits (ASICs) for imaging and spectroscopic applications in space field. The proposed ADC needs only a single low duty-cycle clock signal ‘CLKSampling’ to initiate the conversion process and generates all other required clock signals internally. Unlike conventional ASAR ADCs, this ADC makes use of a unique rising edge only variable delay-cell to introduce desired delay values to the internally generated clock signal. In addition, the ADC features sampling-rate (fs)-reconfigurability, from typical 40 kHz to 167 kHz, with a proportional power consumption. Also, the proposed architecture is flexible with respect to the time-period and duty-cycle of the ‘CLKSampling’ signal, that can be tailored keeping in view the primary requirements of the desired applications. Moreover, the proposed design is equipped with a simple metastability watchdog circuitry. Fabricated in a 0.35 µm CMOS process at 3.3 V supply, the ADC secures a measured ENOB, and Signal-to-Noise-and-Distortion-Ratio (SNDR) of 7.76-bits, and 48.47 dB, respectively at the typical fs of 40 kHz. Measured Integral-Non-Linearity (INL), and Differential-Non-Linearity (DNL) are within one LSB. The ADC normalized figure-of-merit (FoMWN) - proposed to fairly compare high voltage-based ADCs with low voltage-based ADCs - is 476 fJ/C-step at its maximum fs with all the sections of the ADC operating at 3.3 V. The FoMWN improves to 261.7 fJ/c-step and 243 fJ/c-step with the digital section and delay-cell operated at 1.2 V with and without level-shifters power contribution, respectively without any performance deterioration.

A 1.25-GHz multi-amplitude modulator driver in 0.18 μm SiGe BiCOMOS technology for high speed quantum key distribution.

Quantum key distribution (QKD) research has yielded highly fruitful results and is currently undergoing an industrialization transformation. In QKD systems, electro-optic modulators are typically employed to prepare the required quantum states. While various QKD systems operating at GHz repetition frequency have demonstrated exceptional performance, they predominantly rely on instruments or printed circuit boards to fulfill the driving circuit function of the electro-optic modulator. Consequently, these systems tend to be complex with low integration levels. To address this challenge, we have introduced a modulator driver integrated circuit in 0.18 µm SiGe BiCMOS technology. The circuit can generate multiple-level driving signals with a clock frequency of 1.25GHz and a rising edge of ∼50ps. Each voltage amplitude can be independently adjusted, ensuring the precise preparation of quantum states. The measured signal-to-noise ratio was more than 17 dB, resulting in a low quantum bit error rate of 0.24% in our polarization-encoding system. This work will contribute to the advancement of QKD system integration and promote the industrialization process in this field.

Study of Bipolar Inductively Isolated High-Voltage Pulse Source

To meet the application requirements of pulsed power technology in wastewater treatment and other aspects (for example, a scenario that requires a high-voltage pulse source that can output a pulse with a rising edge in the nanosecond range and a device that can stabilize the pulse under high-frequency conditions), this paper designed an inductively isolated bipolar high-voltage pulse source. It consists of three parts: the primary charging power supply, the isolated driver circuit, and the pulse-forming circuit. By using inductance instead of traditional resistance isolation, using the inductance for charging and isolation, the inductance can increase the charging voltage of the capacitor, so the circuit can achieve a higher voltage output. The dual-Marx generator parallel connection design of the pulsed power supply topology, using a primary charging power supply for positive and negative polarity charging, can simultaneously output the reverse polarity and size of high-voltage pulses to achieve a bipolar output, so the load has an effect on the pulse. The equipment was selected on the basis of the design of the isolated driver circuit, primary charging power supply circuit, and pulse-forming circuit for the corresponding simulation, and in the experiment to build a principle model, the tests showed that the pulse source output pulse amplitude range was 0~10 kV (the positive pulse voltage was 5 kV, and the negative pulse voltage was −5 kV), the pulse rising edge was approximately 200 ns, the pulse width was 1 μs, and the frequency range was 0~1 kHz for the pulse source frequency. The power supply was designed to be used in applications such as wastewater treatment.

Optimum design of double-layer target for proton acceleration by ultrahigh intense femtosecond lasers considering relativistic rising edge.

Advances in laser technology have led to ever-increasing laser intensities. As a result, in addition to the amplified spontaneous emission and pedestal, it has become necessary to accurately treat the relativistic rising edge component. This component has not needed much consideration in the past because of its not relativistic intensity. In the previous study, a thin contamination layer was blown away from the target by the rear sheath field due to the relativistic rising edge component, and the target bulk was accelerated by the sheath field due to the main pulse. These indicated that the proton acceleration is not efficient in the target normal sheath acceleration by the ultrahigh intense femtosecond laser if the proton-containing layer is as thin as the contamination layer. Here we employ a double-layer target, making the second (rear) layer thick enough not to be blown away by the rising edge, so that the second layer is accelerated by the main pulse. The first layer is composed of heavy ions to reduce the total thickness of the target for efficient proton acceleration. We investigate an optimal design of a double-layer target for proton acceleration by the ultrahigh intense femtosecond laser considering the relativistic rising edge using two-dimensional particle-in-cell simulations. We also discuss how to optimize the design of such a double-layer target and find that it can be designed with two conditions: the first layer is not penetrated by hole boring, and the second layer is not blown away by the rising edge.

Influence of frequency on the partial discharge characteristics of biaxially oriented polypropylene film under nanosecond pulse voltage

Partial discharge (PD) is one of the key factors leading to premature insulation failure of film capacitors used in pulse power devices. To study the effect of frequency on the PD characteristics of biaxially oriented polypropylene (BOPP) film, a sphere-plate electrode was used to simulate defects of the air gap between the film layers. PD experiments of the BOPP film were carried out under 1, 10, 100, 500 Hz, and 1 kHz with a rising edge of 65 ns and a pulse width of 300 ns. The results show that the repetitive partial discharge inception voltage (RPDIV), the number of discharges, the rising stage discharge (RSD) amplitude, and the falling stage discharge (FSD) time-lag, all show an increase and then decrease with increasing pulse frequencies and reach a maximum value at a pulse frequency of 100 Hz. Moreover, the FSD discharge amplitude and the RSD discharge time-lag increase with an increasing pulse frequency. From the perspective of initial electron generation, the quantitative mathematical relationship between PD characteristics (RPDIV, PD amplitude, PD number, and PD time-lag) and frequency was established based on the Fowler–Nordheim field emission effect for the first time, which can reflect the influence of frequency on the memory effect and the development process of PD. The results can provide an experimental basis and a mechanistic explanation for the evaluation of PD characteristics for film capacitors under nanosecond pulse voltage.

The real exchange rate and economic growth: a meta-analysis

PurposeEmpirical studies regarding the impact of the real exchange rate (RER) on economic growth are extensively available. However, the literature as a whole appears to report varying results, while the causes of such differences have not been analyzed systematically. The present study aims to fill the gap in the literature.Design/methodology/approachIn this paper, the authors compile 543 empirical estimates from 51 studies of the exchange rate-growth nexus in order to meta-analyze its relationship. Meta-analysis allows the authors to quantitatively synthesize previous empirical studies and explain the variation in the results. This method also enables us to investigate the possibility of publication bias, as there is a tendency in research only to report results that are both statistically significant and show the expected signs.FindingsAfter addressing publication bias and heterogeneity in the estimates, the meta-regression results show that RER depreciation (or undervaluation) genuinely favors economic growth. On average, RER depreciation has a greater impact on economic growth in developing countries than the developed ones. The study’s results imply that maintaining an undervalued RER could be favorable to spur economic growth, especially in developing countries.Originality/valueInitially predominant in the medical literature, meta-analysis has been on a rising edge in economics. This progress has produced many systematic quantitative review analyses with continuously improved statistical-econometric practices related to economic variables. However, to the authors’ knowledge, no comprehensive meta-regression analysis of the relationship between exchange rate and economic growth has been conducted and published in any publicly accessible academic outlet. Therefore, this study aims to fill this gap in the literature.

Accurate Measurement of Frozen Soil Depth Based on I-TDR

In this study, a new method for determining the depth of frozen soil, Impulse Response Time Domain Reflectometry, is discussed. This method uses the principle of impedance measurement and the law of time–frequency domain convolution to convert the frequency-domain reflection signal into a time-domain signal and accurately determines the soil freezing front by measuring the difference between the impedance of frozen soil and unfrozen soil. The advantage of this method is that it solves the problems of small bandwidth, long rising edge time, and large measurement errors in the traditional TDR method to effectively improve the measurement accuracy of the soil-freezing front. Under laboratory conditions, soils of different textures (sand, loess, black soil, and red soil) were selected for experimental determination, and the results showed that compared with the traditional TDR method, the RMSE of the I-TDR method was small, and the method was applicable under different soil texture conditions, which could provide a new method for monitoring frozen soil in cold areas. In addition, the application of this method has important guiding significance for improving the efficiency of winter irrigation water, especially for guiding agricultural production, farmland irrigation, drainage engineering construction, meteorological frozen soil monitoring, and other aspects in cold and arid areas.

Effects of pulse rise time on electron dynamics properties in nitrogen–oxygen mixture under repetitive nanosecond pulses

The effects of pulse rise time on the temporal evolution of electron energy and density under repetitive nanosecond pulses in atmospheric nitrogen with 100 ppm oxygen impurities are investigated in this paper by a two-dimensional particle-in-cell/Monte Carlo collision model. It is found that the peak value of mean electron energy increases with decreasing pulse rise time in the single pulsed discharge. However, in the repetitive pulsed discharge approximated by pre-ionization, the peak value of mean electron energy no longer varies with the pulse rise time, showing a saturation trend with decreasing pulse rise time. Whether or not pre-ionization is present, the time required for the mean electron energy to reach its peak is approximately equal to the pulse rise time. It is worth noting that the presence of pre-ionization enhances the tracking ability of the mean electron energy to the pulse waveform during the pulse rise edge. Although after the peak of the pulse, the mean electron energy terminates the tracking process to pulse waveform due to the formation of high-density avalanches and even streamers, its energy decay rate gradually decreases with the increase in the pre-ionization density. Therefore, when the pulse repetitive frequency is greatly increased or the pre-ionization density is increased by other means, it is possible to achieve the complete control of the mean electron energy by pulse waveform modulation.

Research on Pulse Shaper Based on Trapezoidal Function

In order to improve the time resolution and spatial resolution of photon-counting imaging system, the pulse shaper based on trapezoidal function is studied. The signal with an exponential decay shape from charge sensitive amplifier is converted to digital discrete signal by ADC and then the discrete number sequence is filtered and shaped by digital signal processing technology. The amplitude linearity and time width of the trapezoidal shaper are simulated and verified using software-generated single exponential signals and double exponential signals. While the continuous pulses are applied to the trapezoidal shaper, the separation characteristics of the trapezoidal algorithm for pulses pile-up is verified, and the setting method of the rise edge and fall edge parameters of the trapezoidal shaper is proposed, which can realize the high counting capability of the system.