Large Dynamic Range Research Articles

Highlighting Water-Bearing Zones in Tunnel by Inverse Wavefield Transform of TEM Data

Transient electromagnetic method (TEM) is an effective tool to map the groundwater distribution in tunnel construction. To highlight the structural information of the water-bearing zones, inverse wavefield transform is used to extract pseudo-wavefield from TEM data. To provide accurate and reliable pseudo-wavefield, pseudo-wavefield extraction should tackle the large dynamic range of the kernel function, ill-posed inverse transform function, and self-adaptive solving. In this paper, a series of works had been done to solve the above problems. Based on the property of the wavefield transform and its kernel function, we provided an empirical formula to shorten the integral interval of the inverse wavefield transform. A self-adaptive method combined with the precise integral method (PIM) was conducted to provide accurate equation solving. The data misfit between the modeling data and the fitted data is less than 2.5% in our numerical models. The traces of the pseudo-wavefield highlight the boundary of the low-resistivity layers of different depths and thicknesses. For the field data measured in a constructing tunnel, the reflection in our pseudo-wavefield traces provided massive subsurface electrical interfaces with a data misfit of less than 5%. Combined with the low-resistivity zones in the apparent resistivity results, three water-bearing zones were highlighted and then verified by a drilling test, which confirms the reliability and practicality of our method.

RAM: Rapid Advection Algorithm on Arbitrary Meshes

The study of many astrophysical flows requires computational algorithms that can capture high Mach number flows, while resolving a large dynamic range in spatial and density scales. In this paper we present a novel method, RAM: Rapid Advection Algorithm on Arbitrary Meshes. RAM is a time-explicit method to solve the advection equation in problems with large bulk velocity on arbitrary computational grids. In comparison with standard upwind algorithms, RAM enables advection with larger time steps and lower truncation errors. Our method is based on the operator splitting technique and conservative interpolation. Depending on the bulk velocity and resolution, RAM can decrease the numerical cost of hydrodynamics by more than one order of magnitude. To quantify the truncation errors and speed-up with RAM, we perform one- and two-dimensional hydrodynamics tests. We find that the order of our method is given by the order of the conservative interpolation and that the effective speed-up is in agreement with the relative increment in time step. RAM will be especially useful for numerical studies of disk−satellite interaction, characterized by high bulk orbital velocities and nontrivial geometries. Our method dramatically lowers the computational cost of simulations that simultaneously resolve the global disk and potential well inside the Hill radius of the secondary companion.

Alterable interferential fineness for high temperature sensing calibration based on Bragg hollow core fiber.

We propose, what we believe to be, a novel method for high temperature sensing calibration based on the mechanism of alterable interferential fineness in Bragg hollow core fiber (BHCF). To verify the proof-of-concept, the fabricated sensing structure is sandwiched by two sections with different length of BHCF. Two interferential fineness fringes dominate the transmission spectrum, where the high-fineness fringes formed by anti-resonant reflecting optical waveguide (ARROW) plays the role for high temperature measurement. Meanwhile, the low-fineness fringes induced by short Fabry-Perot (F-P) cavity are exploited as temperature calibration. The experimental results show that the ARROW mechanism-based temperature sensitivity can reach 26.03 pm/°C, and the intrinsic temperature sensitivity of BHCF is 1.02 pm/°C. Here, the relatively lower magnitude of the temperature sensitivity is considered as the standard value since it merely relies on the material properties of silicon. Additionally, a large dynamic temperature range from 100 °C to 800 °C presents linear response of the proposed sensing structure, which may shine the light on the sensing applications in the harsh environment.

Analog Ion‐Slicing LiNbO3 Memristor Based on Hopping Transport for Neuromorphic Computing

Inspired by human brain, the emerging analog‐type memristor employed in neuromorphic computing systems has attracted tremendous interest. However, existing analog memristors are still far from accurate tuning of multiple conductance states, which are crucial from the device‐level view. Herein, a reliable analog memristor based on ion‐slicing single‐crystalline LiNbO3 (LNO) thin film is demonstrated. The highly ordered LNO crystal structure provides a stable pathway of oxygen vacancy migration, which is contributed to a stable Mott variable‐range hopping process in trap sites. Excellent analog switching characteristics with high reliability and repeatability, including long retention/great endurance with small fluctuation (fluctuated within 0.22%), a large dynamic range of two orders of magnitude, hundreds of distinguishable conductance states with tunable linearity, and ultralow cyclic variances for multiple weight updating (down to 0.75%), are realized with the proposed memristor. As a result, a multilayer perceptron with a high recognition accuracy of 95.6% for Modified National Institute of Standards and Technology dataset is realized. The proposed analog memristive devices based on ion‐slicing single‐crystalline thin films offer a novel strategy for fabricating high‐performance memristors that combined linear tunability and long‐term repeatability, opening a novel avenue for neuromorphic computing application.

Reverse-distribution phase featured gradient heterojunction: A universal strategy to realize high-performance near-infrared organic photodetectors for real-time arterial monitoring

Near-infrared (NIR) organic photodetectors (OPDs) play significant roles in night vision, optical communication and bio-imaging for low cost, easy fabrication and flexibility. However, their development is facing a serious challenge that efforts on suppressing typically high dark current density (JD) generally encounter photoresponse loss because of accompanying with less exciton generation or poorer carrier extraction. Here, novel structure and mechanism are pioneered to overcome that challenge: forming a reverse-distribution phase featured gradient heterojunction (RP-GHJ) to build an effective charge transport channel. In such structure, increased barriers are established to prevent unfavorable charge injection for suppressing JD. Additionally, photogenerated carriers are wrapped by anti-recombination region in reverse phase for efficient charge extraction. Therefore, RP-GHJ suppresses JD of NIR-OPDs to 8.48 × 10−9 A cm−2 which is far superior to 1.81 × 10−6 A cm−2 of traditional BHJ one (bias of −1 V) and simultaneously keeps high photoresponse. Consequently, RP-GHJ makes NIR-OPD realize stable-high detectivity over 1013 Jones at bias region from 0 to − 0.5 V and when the bias increases from − 0.5 to − 1 V, decrease of specific detectivity is slight (under 830 nm). And more importantly, a very large linear dynamic range of nearly 160 dB is obtained under 0 V bias. The structure is proven to be universally effective in NIR-OPDs and a highly sensitive arterial pulse monitoring is developed. The novel structure and mechanism provide a universal strategy for realizing high-performance NIR-OPDs and their real applications.

Large dynamic range terahertz phase modulator based on graphene-metal hybrid metasurface

Terahertz (THz) dynamic phase modulator is indispensable in THz wireless communications, high-resolution imaging and radar systems. However, up to now, it is difficult to achieve dynamic tunable phase shift of more than 150 degrees in single-layer transmission mode. In this work, we proposed a THz dynamic large phase modulator based on graphene-metal hybrid metasurface. The simulation results show that, when the Fermi level of graphene changes from 0 eV to 0.86 eV, the phase shift exceeds 176 degrees. By modifying the structural parameters, a phase shift of 170 degrees can be achieved in a bandwidth of 50 GHz. We investigated the physical mechanism of the dynamic phase modulator, and established the relationship between phase shift and Fermi level theoretically. This study paves a new way for realizing dynamic large phase modulation, which is very important for the THz broadband wireless communication, high-resolution imaging and radar system.

Parallel Cross-Correlation Algorithm for the Fast Interrogation of High-Finesse Fiber-Optic Fabry-Perot Sensors

It is still a challenge to realize the absolute optical path difference (OPD) demodulation of the high-finesse fiber-optic Fabry-Perot (FP) sensors with a high resolution and high speed. This paper proposes an improved parallel cross-correlation (PCC) algorithm for the absolute OPD interrogation of the high-finesse FP sensors. The proposed demodulation algorithm is simulated and analyzed to verify the feasibility of the algorithm for sensors with different reflectivity or OPDs with large dynamic range. A high-finesse fiber-optic FP pressure sensor with a cavity length of about 1500 µm and reflectivity of 62.5% has been used to carry out the experiment. Results show that the measurement resolution of the PCC algorithm can reach the sub-nanometer level, the sensor' sensitivity is about 3.93 nm/KPa, which is similar to the theoretical value. By exploring the effect of reflectivity on the demodulation results, it is found out that accurate results are still obtainable even though the exact reflectivity is unknown. In addition, thanks to the multi-threading of computers and the parallel computing method proposed in this paper, the demodulation speed would be further improved.

Optimal force-balance control of closed-loop sensing systems with time delay

Differing from the response control in civil and engineering applications, the excitation in a closed-loop sensing system is unknown and the control is designed to balance and measure the unknown excitation in real time. In this paper, a novel optimal force-balance control for a closed-loop sensing system with time delay is proposed. By introducing the errors between the control force and the unknown input as new variables, the force-balance control problem is transformed into a response minimization one with a time delay. Then, the discretization method is applied, and the continuous time system with time delay is converted into an extended discrete system without time delay, from which the analytical expression of the optimal force-balance control force is obtained. To illustrate the effectiveness of the proposed control, the optimal control of a practical quartz flexible force-balance accelerometer (FBA) is solved as an application. Numerical results show that the proposed control can realize the accurate measurement of wide-band random acceleration signals with a time delay of up to 10 times of control period. Besides, the proposed control can also significantly inhibit the vibration response of the FBA while guaranteeing measurement accuracy, which will benefit the obtaining of a large dynamic measurement range as a sensing application.

Development of biosensors highly responsive to N-acetylneuraminic acid in Bacillus subtilis

Bacillus subtilis is recognized as a generally-regarded-as-safe strain, and has been widely used in the biosynthesis of high value-added products, including N-acetylneuraminic acid (NeuAc) which is widely used as a nutraceutical and a pharmaceutical intermediate. Biosensors responding to target products are widely used in dynamic regulation and high-throughput screening in metabolic engineering to improve the efficiency of biosynthesis. However, B. subtilis lacks biosensors that can efficiently respond to NeuAc. This study first tested and optimized the transport capacity of NeuAc transporters, and obtained a series of strains with different transport capacities for testing NeuAc-responsive biosensors. Subsequently, the binding site sequence of Bbr_NanR responding to NeuAc was inserted into different sites of the constitutive promoter of B. subtilis, and active hybrid promoters were obtained. Next, by introducing and optimizing the expression of Bbr_NanR in B. subtilis with NeuAc transport capacity, we obtained an NeuAc-responsive biosensor with wide dynamic range and higher activation fold. Among them, P535-N2 can sensitively respond to changes in intracellular NeuAc concentration, with the largest dynamic range (180-20 245) AU/OD. P566-N2 shows a 122-fold of activation, which is 2 times of the reported NeuAc-responsive biosensor in B. subtilis. The NeuAc-responsive biosensor developed in this study can be used to screen enzyme mutants and B. subtilis strains with high NeuAc production efficiency, providing an efficient and sensitive analysis and regulation tool for biosynthesis of NeuAc in B. subtilis.

Experimental Optimization of the Energy Characteristics of a Ground Penetrating Radar with Continuous Linear-Frequency-Modulated Radiation

In recent years, research has been actively carried out aimed at developing the concept of construction and ways of technical implementation of ground penetrating radars with continuous wave linear-frequency-modulated (LFM) radiation. The key prerequisites for the creation of such systems are the complex consideration of the operating conditions of the radio channel in the near field, including the features associated with multichannel leakage of the probing signal components into the reception path, the presence of multipath reflections from the covering surface, the variable speed of the electromagnetic wave, and the provision of linear processing of a continuous group broadband radio signal with large dynamic range. The paper proposes and describes a scheme of a laboratory stand for LFM GPR research and optimization of the energy characteristics in modes with critical levels of reflections. The results of experiments on the analysis and optimization of the parameters of the end-to-end transfer characteristic of the radio channel are presented. Response studies were performed for two types of antennas at different suspension heights. The responses of the system to an increase in the durtion of the probing pulse and a change in the type of window function were evaluated. An empirical dependence of signal losses during propagation in radio channels of LFM GPR has been established. The conducted studies will improve the energy characteristics of ground penetrating radars with continuous LFM radiation by increasing the detection efficiency of shallow and near-surface objects.

A dual paths magnetorheological damper with small field-off force and large dynamic range

Magnetorheological (MR) dampers are widely used for vibration isolation and the dynamic range is a key index to evaluate its performance. According to the vibration isolation theory, it is essential for the damper to maximize the damping force in resonance region and minimize the damping force in high-frequency excitation. However, for single-path MR dampers, achieving the goals of low field-off force and large dynamic range has conflicting requirements on the structural parameters. In this research, a dual paths MR damper has been proposed to overcome this problem. The proposed MR damper has two coaxial paths and the magnetic field strength in each path can be controlled separately. According to the flow state of the MR fluid, the working modes of the proposed MR damper are divided into three kinds and the corresponding mathematical models are driven. Based on the mathematical models, the effect of structural parameters on the dynamic range, maximum and minimum damping force is investigated. It is concluded that increasing the piston rod radius and piston length is an effective method to expand the dynamic range while maintain a small field-off damping force. The experimental results show that the proposed MR damper working mode can be controlled by the applied currents, the minimum force is obtained in the dual paths flow state while the maximum force is obtained in the inner path flow state. In particular, the dynamic range of the proposed MR damper is significantly improved to 93.3 and the filed-off damping force remains small compared to the previously reported MR damper.

Ameliorated PGC demodulation scheme using Taubin least squares fitting of ellipse in fiber optic interferometric sensors

In this paper, we propose an ameliorated phase generated carrier (PGC) demodulation scheme using Taubin least squares (LS) fitting of ellipse to eliminate the nonlinear errors. Taubin LS has carefully chosen a normalization matrix and the ellipse fitting parameters are directly obtained by solving the generalized eigenvector problem, leading to a high accuracy result. Quadrature signals are extracted from the signal fundamental and the sidebands of the fundamental of the carrier, and then corrected by the ellipse fitting algorithm (EFA) based on Taubin LS. A combined internal modulation is used to ensure the proper operation of the EFA under small signals. And the desired phase signal is extracted from the corrected quadrature signals by the differential-cross-multiplying method and evaluated by the total harmonic distortion. Experimental results show that the proposed scheme is superior and highly stable, it has a phase resolution of 3.16 μrad/√Hz, a large dynamic range of 120 dB @ 1 KHz and a good linearity of better than 99.99%.

A laser absorption sensor for fuel slip monitoring in high-humidity flue gases from ammonia combustion

Ammonia has been recently recognized as a promising carbon-free fuel to help decarbone both the power and industrial heating sectors. However, fuel slip during ammonia combustion is of high concern because of the high toxicity of the chemical, motivating the development of sensitive sensors for real-time monitoring of ammonia emission in combustion flue gases. In this work, a near-infrared absorption spectroscopic sensor was developed for trace ammonia (NH3) measurements in high-humidity flue gas environments with water vapor (H2O) mole fractions up to 40%. The focus on high humidity is motivated by the facct that ammonia combustion generally leads to flues gases with notably higher water vapor concentations as compared to conventional hydrocarbons. The sensor used a distributed feedback laser to target the NH3 absorption line near 6612.73 cm−1. Proof-of-concept tests were conducted in a high-temperature multi-pass cell with a controlled temperature of 500 K and pressure of 1 atm. A custom-designed variable humidity generator was used to provide a reference NH3/N2 mixture with a controlled H2O mole fraction (10%–40%) to simulate ammonia combustion flue gases. Direct absorption spectroscopy and wavelength modulation spectroscopy were both used to ensure a relatively large dynamic range. H2O-induced broadening effects on the measured absorption profile were quantified. The developed sensor was firstly validated against NH3/N2 mixtures with different H2O concentrations, with a lower detection limit of 76 ppb achieved. Real-time measurements of NH3 slip in the flue gases from CH4/NH3/air flames and CH4/NH3 co-firing industrial furnace were performed as a demonstration of the sensor for time-resolved ammonia monitoring with sufficient accuracy, sensitivity, and time response.

Lensfree Air-Quality Monitoring of Fine and Ultrafine Particulate Matter Using Vapor-Condensed Nanolenses.

Current commercial air-quality monitoring devices lack a large dynamic range, especially at the small, ultrafine size scale. Furthermore, there is a low density of air-quality monitoring stations, reducing the precision with which local particulate matter hazards can be tracked. Here, we show a low-cost, lensfree, and portable air-quality monitoring device (LPAQD) that can detect and measure micron-sized particles down to 100 nm-sized particles, with the capability to track and measure particles in real time throughout a day and the ability to accurately measure particulate matter densities as low as 3 μg m-3. A vapor-condensed film is deposited onto the coverslip used to collect particles before the LPAQD is deployed at outdoor monitoring sites. The vapor-condensed film increases the scattering cross section of particles smaller than the pixel size, enabling the sub-pixel and sub-diffraction-limit-sized particles to be detected. The high dynamic range, low cost, and portability of this device can enable citizens to monitor their own air quality to hopefully impact user decisions that reduce the risk for particulate matter-related diseases.

A High-Power Capacity Transistor-Based Rectifier With Wide Input Power Range

This letter proposes a methodology for realizing the rectifier with a wide radio frequency (RF) input power range for large power capacity applications. The comprehensive analysis is given in this letter under the condition of class-F operation mode. The optimum conduction angle of the transistor corresponding to the maximum input power dynamic range is determined. Theoretical rectification efficiency of over 60% can be obtained in a 30 dB in-depth input power level. For validation, an RF-dc rectifier operating at 2.45 GHz is designed based on the GaN transistor. Measurements demonstrate that the rectification efficiency of between 60.4% and 82.1% is realized with a fixed dc load of 115 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $</tex-math> </inline-formula> when the RF input power is from 18 to 43 dBm. To the best of the authors’ knowledge, it is the first realization of a transistor-based RF-dc rectifier with a large input dynamic range of over 25 dB. The proposed rectifier shows great potential to be used in future high-power wireless power transfer (WPT) applications.

Measurement System of the Mean and Sub-Cycle LV Grid Access Impedance From 20 kHz To 10 MHz

This work presents a novel measurement method to characterize long-term and short-term variations of the LV grid impedance from 20 kHz to 10 MHz with configurable time, frequency and amplitude resolutions. The characterization of the grid access impedance in this frequency range is vital for the design and development of NB-PLC and BB-PLC technologies. The measurement system is valid for in-home, indoor cable networks and for the harsh conditions of the LV distribution grid, where a large input dynamic range and strong protection mechanisms against high-amplitude impulsive noises are required. Its accuracy is evaluated by comparison to a precision impedance meter for a wide set of impedance values, obtaining a maximum deviation within ± 8%. First trials of the grid impedance sub-cycle variations caused by commercial appliances and for frequencies assigned to BB-PLC are also presented in this paper. The results demonstrate that the grid impedance is highly time-varying within the mains cycle, both in amplitude and phase. These first outcomes point at the need to evaluate the accumulative effects of sub-cycle variations in the LV distribution grid, so that equalization algorithms in the next BB-PLC technologies could be developed to overcome the impact of these fast variations.

Current mode multi scroll chaotic oscillator based on CDTA

Compared to voltage mode circuits, current mode circuits have advantages such as large dynamic range, fast speed, wide frequency band, and good linearity. In recent years, the development of call flow modeling technology has been rapid and has become an important foundation for analog integrated circuits. In this paper, a current mode chaotic oscillation circuit based on current differential transconductance amplifier (CDTA) is proposed. This proposed circuit fully utilizes the advantages of current differential transconductance amplifier: a current input and output device with a large dynamic range, virtual ground at the input, extremely low input impedance, and high output impedance. The linear and non-linear parts of the proposed circuit operate in current mode, enabling a true current mode multi scroll chaotic circuit. Pspice simulation results show that the current mode chaotic circuit proposed can generate multi scroll chaotic attractors.

Laser Linewidth Analysis and Filtering/Fitting Algorithms for Improved TDLAS-Based Optical Gas Sensor.

Tunable Diode Laser Absorption Spectroscopy (TDLAS) has been widely applied in in situ and real-time monitoring of trace gas concentrations. In this paper, an advanced TDLAS-based optical gas sensing system with laser linewidth analysis and filtering/fitting algorithms is proposed and experimentally demonstrated. The linewidth of the laser pulse spectrum is innovatively considered and analyzed in the harmonic detection of the TDLAS model. The adaptive Variational Mode Decomposition-Savitzky Golay (VMD-SG) filtering algorithm is developed to process the raw data and could significantly eliminate the background noise variance by about 31% and signal jitters by about 12.5%. Furthermore, the Radial Basis Function (RBF) neural network is also incorporated and applied to improve the fitting accuracy of the gas sensor. Compared with traditional linear fitting or least squares method (LSM), the RBF neural network brings along the enhanced fitting accuracy within a large dynamic range, achieving an absolute error of below 50 ppmv (about 0.6%) for the maximum 8000 ppmv methane. The proposed technique in this paper is universal and compatible with TDLAS-based gas sensors without hardware modification, allowing direct improvement and optimization for current optical gas sensors.

Real-time frequency estimation of a qubit without single-shot-readout

Quantum sensors can potentially achieve the Heisenberg limit of sensitivity over a large dynamic range using quantum algorithms. The adaptive phase estimation algorithm (PEA) is one example that was proven to achieve such high sensitivities with single-shot readout (SSR) sensors. However, using the adaptive PEA on a non-SSR sensor is not trivial due to the low contrast nature of the measurement. The standard approach to account for the averaged nature of the measurement in this PEA algorithm is to use a method based on ‘majority voting’. Although it is easy to implement, this method is more prone to mistakes due to noise in the measurement. To reduce these mistakes, a binomial distribution technique from a batch selection was recently shown theoretically to be superior, as all ranges of outcomes from an averaged measurement are considered. Here we apply, for the first time, real-time non-adaptive PEA on a non-SSR sensor with the binomial distribution approach. We compare the mean square error of the binomial distribution method to the majority-voting approach using the nitrogen-vacancy center in diamond at ambient conditions as a non-SSR sensor. Our results suggest that the binomial distribution approach achieves better accuracy with the same sensing times. To further shorten the sensing time, we propose an adaptive algorithm that controls the readout phase and, therefore, the measurement basis set. We show by numerical simulation that adding the adaptive protocol can further improve the accuracy in a future real-time experiment.

Research on calculation strategy of perimeter of irregular objects

Image processing is a burgeoning subject in recent decades, which combines related theories with modern high technology to systematically study various image theories, technologies and applications. In the problem of industrial precision dimension detection, the edge of the obtained target image is rough and noisy due to the manufacturing accuracy, breakage and corrosion of the workpiece, which makes automatic detection difficult. Therefore, it has become a difficult problem to accurately extract the characteristic curve of the target edge in the development of industrial automatic detection system. Image measurement method has the advantages of non-contact, high speed, large dynamic range and rich information, and is widely used in the field of measurement. This paper introduces the principle of foot type three-dimensional contour measurement based on the light cutting method. Aiming at the composition of a multi CCD light cutting measurement system, a new method for high-precision extraction of the center line of the contour light band using the combination of central axis tracking and improved deflection measurement principle is proposed. The extraction and processing process of the light cutting surface contour image is described in detail, and through the coordinate transformation of the extracted center line, The complete profile data of the foot profile are obtained. The experimental results show that the processing effect of this method is satisfactory.