Amplitude Shift Research Articles

Ultrafast Detection and Discrimination of Methanol Gas Using a Polyindole-Embedded Substrate Integrated Waveguide Microwave Sensor.

The fast and sensitive detection of methanol gas using cost-effective sensors in the industry is a significant issue to be addressed. Herein, a polyindole (PIn)-deposited substrate integrated waveguide (SIW) has been introduced to perform quantitative and qualitative methanol gas sensing with quick response and recovery time at room temperature. First, PIn is synthesized and deposited in the microwell etched at the intensified electric field region of the microwave-based cavity resonator, which gives a sensing response through variation of PIn's high-frequency conductivity and dielectric property caused by the adsorption and desorption of methanol gas. Second, an enhanced filling factor and high Q factor have been attained using the proposed microwell etched SIW structure, which exhibits high sensitivity in terms of frequency shift (3.33 kHz/ppm), amplitude shift (0.005 dB/ppm), bandwidth broadening (3.66 kHz/ppm), and loaded Q factor (10.60 Q value/ppm). Third, the gas measurement results reveal excellent long-term stability with a relative standard deviation (RSD) of 0.02% for 7 days, excellent repeatability with an RSD of 0.004%, and desired response and recovery time of 95 and 120 s, respectively. The results indicate that the proposed microwave sensor has great potential to achieve high sensitivity and fast response toward methanol gas molecules at room temperature.

A Bayesian stochastic generator to complement existing climate change scenarios: supporting uncertainty quantification in marine and coastal ecosystems

Available climate change projections, which can be used for quantifying future changes in marine and coastal ecosystems, usually consist of a few scenarios. Studies addressing ecological impacts of climate change often make use of a low- (RCP2.6), moderate- (RCP4.5) or high climate scenario (RCP8.5), without taking into account further uncertainties in these scenarios. In this research a methodology is proposed to generate further synthetic scenarios, based on existing datasets, for a better representation of climate change induced uncertainties. The methodology builds on Regional Climate Model scenarios provided by the EURO-CORDEX experiment. In order to generate new realizations of climate variables, such as radiation or temperature, a hierarchical Bayesian model is developed. In addition, a parameterized time series model is introduced, which includes a linear trend component, a seasonal shape with varying amplitude and time shift, and an additive residual term. The seasonal shape is derived with the non-parametric locally weighted scatterplot smoothing, and the residual term includes the smoothed variance of residuals and independent and identically distributed noise. The distributions of the time series model parameters are estimated through Bayesian parameter inference with Markov chain Monte Carlo sampling (Gibbs sampler). By sampling from the predictive distribution numerous new statistically representative synthetic scenarios can be generated including uncertainty estimates. As a demonstration case, utilizing these generated synthetic scenarios and a physically based ecological model (Delft3D-WAQ) that relates climate variables to ecosystem variables, a probabilistic simulation is conducted to further propagate the climate change induced uncertainties to marine and coastal ecosystem indicators.

Ultrasonic wireless communication using capacitive micromachined ultrasonic transducers in liquid with OOK digital modulation

The modulation scheme of ultrasonic communication using capacitive micromachined ultrasonic transducers, acting as the transmitted port and received port, was simulated and experimented with four parallel channels in silicone oil. Four channel signals were coded by a steady and reliable binary amplitude shift keying method such as on–off keying modulation. The modulation scheme was simulated with additive Gaussian noise and attenuated for every channel in silicone oil, and the sound attenuation influence was evaluated with different distances. The capacitive micromachined ultrasonic transducers were measured to achieve a −6 dB bandwidth of 305 kHz when operating in silicone oil. The channels were operated at different frequencies ranging from 300 kHz to 600 kHz with a channel spacing of 100 kHz. The bit rate of 50 kbps for one channel was achieved with a data rate of 200 kbps over a short-range distance of 0.1 m. The proposed correction coefficient could be used to adjust the threshold. The high overall signal-to-noise ratio of 29.41 dB ensured the system to have a low-level bit error rate.

Integrated performance of large HDC-capsule implosions on the National Ignition Facility

We report on eight, indirect-drive, deuterium–tritium-layered, inertial-confinement-fusion experiments at the National Ignition Facility to determine the largest capsule that can be driven symmetrically without relying on cross-beam energy transfer or advanced Hohlraum designs. Targets with inner radii of up to 1050 μm exhibited controllable P2 symmetry, while larger capsules suffered from diminished equatorial drive. Reducing the Hohlraum gas-fill-density from 0.45 mg/cm3 to 0.3 mg/cm3 did not result in a favorable shift of P2 amplitude as observed in preceding tuning experiments. Reducing the laser-entrance-hole diameter from 4 mm to 3.64 mm decreased polar radiation losses as expected, resulting in an oblate symmetry. The experiments exhibited the expected performance benefit from increased experimental scale, with yields at a fixed implosion velocity roughly following the predicted 1D dependence. With an inner radius of 1050 μm and a case-to-capsule-ratio of 3.0, experiment N181104 is the lowest implosion-velocity experiment to exceed a total neutron yield of 1016.

Voltage mode ASK/BPSK modulator, its extended applications in precision rectifier and data communication using DXCCII

In this paper, two new modulator circuits are presented to realize two types of digital modulations, namely amplitude shift keying (ASK) and Binary phase shift keying (BPSK). The modulator circuits use one dual-X second-generation current conveyor (DXCCII), three MOS transistors, and one or two resistors. Since in data communication, there is a need for a demodulator and a modulator, a basic demodulator as an application of ASK modulator is presented using a rectifier, envelope detector, and comparator. Moreover, in an integrated circuit (IC), the modularity of sub-circuit is preferred, especially for the ease of fabrication. In maintaining the modularity, an attempt is made to design a precision rectifier, needed for demodulator, as an extension of the proposed modulator with little modifications. The proposed modulators possess the following important features: use all grounded passive components, ASK and BPSK obtain simultaneously, no need for matching passive components, circuits are fully cascadable and easily extendable to a precision rectifier. A non-ideal analysis is carried out. The proposed circuits are verified by PSPICE simulation with a supply voltage of ±0.9 V in 0.13 µm CMOS TSMC technology. Simulation results corroborate the theoretical proposition. Furthermore, the proposed ASK and BPSK modulator circuit is experimentally verified.

Automatic digital modulation recognition in the presence of alpha-stable noise

In this paper, we introduce a novel modulation recognition method of digital communication signals with alpha-stable noise to solve the problem of low recognition performance in mixed signal-to-noise-ratio environment. The received signals are separated into signals and alpha-stable noise by employing fractional lower order fast independent component analysis (FLO-Fast-ICA), and then the separated signals are interpolated based on the global average local mean decomposition. With these processing, two classification features that are the segmented instantaneous frequency standard deviation and the segmental instantaneous amplitude standard deviation are extracted. Thereafter, a decision tree classifier is developed to recognize the digital communication signals including minimum shift keying (MSK), 2 amplitude shift keying (2ASK), quadrature phase shift keying (QPSK) and 16 quadrature amplitude modulation (16QAM). Simulation results show that the proposed method has a promising performance without prior information.

Transmission of Images on High-Temperature Nuclear-Grade Metallic Pipe with Ultrasonic Elastic Waves

Transmission of information using elastic ultrasonic waves on existing metallic pipes provides an alternative communication option for a nuclear facility. The advantages of this approach consist of transmitting information through barriers, such as the containment building wall, with minimal modification of the existing hardware. Because bit rates on the order of kilobits per second are achievable, relatively large volumes of data, such as images, can be transmitted. A viable candidate for an ultrasonic communication channel is a stainless steel pipe of the chemical volume control system (CVCS) that penetrates through the reactor containment building wall through a sealed tunnel. To study ultrasonic communication under simulated nuclear facility conditions of high temperature, a test article was developed by installing heating tapes, temperature controllers, and thermal insulation on a laboratory CVCS-like stainless steel pipe. High temperature and radiation-resilient lithium niobate ultrasonic transducers were utilized for information transmission on the heated pipe. The amplitude shift keying (ASK) digital communication protocol was developed and implemented in a GNU Radio software–defined radio environment. A root-raised-cosine filter was introduced to suppress ultrasonic transducer ringing and thus reduce inter-symbol interference. This resulted in the enhancement of the data transmission bit rate compared to information encoding with square pulses. Demonstrations of communication at high temperature included transmission of a 90-KB image at the bit rate of 10 Kbps with a bit error rate of 10−3 across a 6-ft-long straight pipe heated up to 230°C. Additional preliminary studies were conducted to evaluate ultrasonic communication system resilience to environmental degradation and damage.

A multi-decadal record of oceanographic changes of the past ~165 years (1850-2015 AD) from Northwest of Iceland.

Extending oceanographic data beyond the instrumental period is highly needed to better characterize and understand multi-decadal to centennial natural ocean variability. Here, a stable isotope record at unprecedented temporal resolution (1 to 2 years) from a new marine core retrieved off western North Iceland is presented. We aim to better constrain the variability of subsurface, Atlantic-derived Subpolar Mode Water (SPMW), using near surface-dwelling planktic foraminifera and Arctic Intermediate Water (AIW) mass changes using benthic foraminifera over the last ~165 years. The reconstruction overlaps in time with instrumental observations and a direct comparison reveals that the δ18O record of Neogloboquadrina pachyderma is reliably representing temperature fluctuations in the SPMWs. Trends in the N. pachyderma δ13C record match the measured phosphate concentration in the upper 200 m on the North Icelandic Shelf well. Near surface-dwelling foraminifera trace anthropogenic CO2 in the Iceland Sea by ~ 1950 ± 8, however, a reduced amplitude shift in the Marine Suess effect is identified. We argue that this is caused by a contemporary ongoing increase in marine primary productivity in the upper ocean due to enhanced Greenland’s freshwater discharge that has contributed to a nutrient-driven fertilization since the 1940s/50s (Perner et al., 2019). Multi-decadal variability is detected. We find that the 16-year periodicity evident in SPMW and AIWs based on the δ18O of N. pachyderma and M. barleeanum is a signal of SST anomalies propagated into the Nordic Seas via the Atlantic inflow branches around Iceland. Spectral analyses of the planktic foraminiferal δ13C signal indicate intermittent 30-year cycles that are likely reflecting the ocean response to atmospheric variability, presumably the East Atlantic Pattern. A long-term trend in benthic δ18O suggests that Atlantic-derived waters are expanding their core within the water column from the subsurface into deeper intermediate depths towards the present day. This is a result of increased transport by the North Icelandic Irminger Current to the North Iceland Shelf over the historical era.

Novel Structure for Waveform Control of Twin Rotary Flowrate Valve Controlled Vibration Exciter

For improving the vibration waveform amplitude and controlling the vertical shift flexibly, a novel structure for waveform control of twin rotary flowrate valve controlled vibration exciter is proposed. Based on the novel principle, the governing equations of the vibration waveform is derived. Furthermore, the experimental verification is carried out with the prototype of a new vibration exciter. From the analysis results of the regulating characteristics of the waveform frequency, amplitude, and vertical shift, the feasibility and practicability of the proposed waveform control method is verified and provides a new idea for further improving the regulating performance of the vibration waveform.

Lift Equivalence and Cancellation for Airfoil Surge–Pitch–Plunge Oscillations

A NACA 0018 airfoil in freestream velocity is oscillated in longitudinal, transverse, and angle-of-attack directions with respect to the freestream velocity, known as surge, plunge, and pitch. The lift-based equivalence method introduces phase shifts between these three motions to construct in-phase sinusoidal components for maximum lift, waveform construction. Lift cancellation is also determined with the exact negative pitch and plunge motion amplitudes found from the equivalence method to achieve out-of-phase wave destruction. Lift cancellation occurs when a combination of these motions is sought to obtain a constant lift magnitude throughout the oscillation cycle. To achieve both equivalence and cancellation of lift, a prescribed pure pitch amplitude through the Theodorsen theory equates the corresponding equivalent plunge amplitude and pitch–plunge phase shift. These Theodorsen, linear superposition findings of pitch–plunge are leveraged toward the Greenberg theory to determine a closed-form, surge–pitch–plunge solution through the addition of a surge–plunge phase shift and optimal surge amplitude for lift cancellation. The lift cancellation surge–pitch–plunge amplitudes define the equivalence amplitude investigated here and theoretically limit the experiment to combinations of the first lift harmonic of the Greenberg theory. The analytical results are then compared with experimental lift force measurements and dye visualization. The normalized lift differences due to unsteady wake and boundary-layer behavior are examined to explore the extents of the Greenberg theory for these cases of lift-based equivalence and cancellation.

Integrated multi-scheme digital modulations of spoof surface plasmon polaritons

The future wireless communications require different kinds of modulation functions to be integrated in a single intelligent device under different scenarios. Here, we propose a multi-scheme digital modulator to achieve this goal based on integrated spoof surface plasmon polaritons (SPP) in different frequency bands. By constructing switchable spoof SPP units, the propagating wave in the proposed spoof SPP waveguide can be manipulated in amplitude domain, frequency domain, and phase domain. As a proof of concept, the integrated multi-scheme digital modulator is experimentally verified to achieve at least three kinds of modulations, including amplitude shift keying, phase shift keying, and frequency shift keying, in a single digital spoof plasmonic waveguide. The simulated and measured results show that the modulator has excellent property of field confinement and is capable of frequency-domain modulation. Hence, the multi-scheme modulation property makes the proposed SPP digital modulator be an effective and reliable candidate for efficient manipulations of SPP waves and for advanced modulation technology

Transient separation cutting characteristic of axial ultrasonic vibration–assisted cutting

Axial ultrasonic vibration–assisted cutting has been proposed and proved preponderance on cutting performance; however, the transient separation cutting characteristic has not been clearly revealed. This paper focuses on the transient separation cutting characteristic of axial ultrasonic vibration–assisted cutting and its influence on the cutting performance. First, the separation cutting criteria, including feed coefficient and phase shift, are established and influence factors, such as feed rate, amplitude, and phase shift, are systematically analyzed. Subsequently, the duty ratio is deduced and calculated, and some features and a control mechanism are introduced. In addition, a transient separation cutting model with four stages is demonstrated. The reason for the average cutting force reduction by the transient separation cutting characteristic is also stated. Finally, the verification of the separation cutting and transient separation cutting model and the comparison of the feed thrust force and parameter influences on the cutting performance are experimentally performed. The transient signals of different duty ratios 0.55 to 1 are obtained, and 10 to 40% reductions of feed thrust are measured both by a PCB sensor and a Kistler dynamometer. The influence degree of the feed coefficient, spindle rotation speed, and cutting depth on the performance is analyzed. A parameter combination of smaller feed coefficient, moderate spindle rotation speed, and smaller cutting depth is suggested to obtain a better cutting performance by fully considering the cutting force, surface roughness, and tool life.

Kirigami-Enabled Microwave Resonator Arrays for Wireless, Flexible, Passive Strain Sensing.

Wireless and highly sensitive flexible strain sensors would have widespread application across a number of different fields. Here, the novel combination of two different metamaterials, one mechanical and one electronic, is demonstrated for its potential as such a sensor. An array of split-ring resonators (SRRs) were mounted on a bespoke kirigami sheet. The hybrid kirigami structure was designed specifically for the resonator array, in terms of both its physical dimensions and elastic response. Mechanical tests in concert with finite element modeling confirmed that the hybrid kirigami structure, containing two disparate kirigami motifs, exhibited a high range of strain and out-of-plane rotation without plastic deformation. The microwave sensing was designed to monitor variations in the S11 response of the resonators as a function of out-of-plane kirigami hinge rotation. The mounted array of SRRs on the hybrid kirigami sheet could wirelessly detect changes in strain with high sensitivity (>30 MHz shift in resonant frequency; >30 dB shift in resonant amplitude) over a large range of strain, from 0.6 to 21.3%.

Compressed sensing–based electromechanical admittance data loss recovery for concrete structural health monitoring

Considerable amount of electromechanical admittance data needs to be collected, transmitted and stored during in-situ and long-term structural health monitoring applications, and data loss could be inevitably met when processing the monitoring electromechanical admittance signals. In this article, an innovative compressed sensing–based approach is proposed to implement data recovery for electromechanical admittance technique–based concrete structural health monitoring. The basis of this approach is to first project the original conductance signature onto an observation vector as sampled data, and then transmit the observation vector with data loss to storage station, and finally recover the missing data via a compressed sensing process. For comparison, both convex optimization theory and orthogonal matching pursuit algorithm are introduced to accomplish the compressed sensing–based electromechanical admittance data loss recovery. Prior detection test of a concrete cube subjected to varied temperatures and practical monitoring experiment of full-scale concrete shield tunnel segment undergone bolt-loosened defects are utilized to validate the feasibility of the proposed approach. In lost electromechanical admittance data recovery process, two types of data loss, namely, single-consecutive-segment loss and multiple-consecutive-segment losses, in sampled data are taken into consideration for sufficiently interpreting the effectiveness and accuracy of the convex optimization and orthogonal matching pursuit approaches. In the temperature recognition and damage identification stage, amplitude and frequency shifts in resonance peaks, cooperated with a common statistical index called root-mean-squared-deviation, are harnessed to achieve the goal after the lossy conductance signatures are recovered. The results show that the orthogonal matching pursuit–based data recovery approach is superior to the convex optimization approach because of its smaller calculation of consumption as well as lower recovered errors.

Late Turonian climate variability in the Bohemian Cretaceous Basin – A sclerochronological study of Inoceramus hercules shells from the Úpohlavy quarry (Czech Republic)

The δ18O record of well-preserved shells of the inoceramid Inoceramus hercules from the Úpohlavy working quarry (Czech Republic) provides an insight into the climate variability in the late Turonian benthic environment of the Bohemian Cretaceous Basin. Similar to modern bivalves, this inoceramid species built its shell near equilibrium with the oxygen isotope value of the ambient water. Due to the nearly year-round shell growth, sequentially sampled δ18O values allowed to estimate the narrowest sub-annual temperatures fluctuations that prevailed during lifetime of the organisms. In accordance with previous studies, reconstructed temperatures suggest colder water conditions (19.0 ± 0.9 °C) during the earliest late Turonian (coinciding with the Hyphantoceras Event; also known as Hitch Wood Event) than during the later part of the substage (20.9 ± 1.1 °C). Climate warming, however, did not affect the sub-annual temperature fluctuations evenly, but predominantly affected the warmest part of the year (at least +4.0 °C). On the contrary, the coldest recorded temperatures remained more or less invariant, varying not (much) more than +1.0 °C across the studied time interval. The observed changes in the benthic temperature estimates likely reflect shifts in seasonal sea surface temperature amplitudes in response to climate forcing. Given the widespread distribution of I. hercules in the upper Turonian–lower Coniacian hemipelagic strata of Europe, the present study sets the basis for future continent-wide sub-annually-resolved climate reconstructions.

Thigh Cuff Effects on Venous Flow Redistribution During 4 Days in Dry Immersion.

PURPOSE: The objective was to quantify the venous redistribution during a 4-d dry immersion (DI) and evaluate the effect of thigh cuffs.METHODS: The study included nine control (Co) and nine subjects wearing thigh cuffs during the daytime (CU). Ultrasound measures were performed Pre-DI, on day 4 AM (D4 AM) and D4 PM: left ventricle stroke volume and ejection fraction (SV, EF), jugular vein volume (JVvol), portal vein diameter (PV), and middle cerebral vein velocity (MCVv). An additional measure of JVvol was performed on Day 1 after 2 h in DI.RESULTS: After 2 h in DI, JVvol increased significantly from Pre in both groups, but increased more in the Co compared to the CU subjects (Co: 0.27 0.15 cm³ to 0.94 0.22 cm³; CU: 0.32 0.13 cm³ to 0.64 0.32 cm³). At D4 AM, SV and EF decreased from Pre (SV: 111 23 cm³ to 93 24 cm³; EF: 0.66 0.07 to 0.62 0.07). JVvol was slightly increased (Co: 0.47 0.22 cm³ CU: 0.35 014 cm³). MCVv and PV remained unchanged from Pre-DI. No difference was found between the two groups for any of the parameters measured. From D4 AM to PM, no significant change was observed for any parameter.CONCLUSION: The results confirm that DI induces, during the first 2-3 h, a significant cephalic fluid shift as observed in spaceflight. During this early phase, the thigh cuffs reduced the amplitude of the fluid shift toward the head, but after 4 d in DI there was only a slight memory (residual) effect of DI on the jugular volume and no residual effect of the thigh cuffs.Arbeille P, Greaves D, Guillon L, Besnard S. Thigh cuff effects on venous flow redistribution during 4 days in dry immersion. Aerosp Med Hum Perform. 2020; 91(9):697702.

<i>Q</i>-factor determitation with seismoacoustis well logs for estimation of distribution of inhomogeneities in artificial grounds

Quality control in geotechnical engineering is becoming an important issue, especially when products are buried underground. Seismoacoustic methods are widely used for investigations in such structures. In this article seismoacoustic well logs from hidden structures (made by jet grouting technology) are being processed with the goal of obtaining additional information about distribution of heterogeneities in improves grounds. Two methods of estimation Q-factor are used: frequency shift method and amplitude ratios method.

Optical wireless systems with ASK & PSK using coupler-based delay line filter

Abstract In free space optics (FSO) optics, the tweaked optical sign is transmitted at different climate conditions like day off, Mist, and Haze, which is a new paragon to the field of optical communication. Further to realize the same, the present research analyzes the framework performance by executing two adjustment strategies amplitude shift keying (ASK) and Phase shift keying (PSK). Moreover, article investigates the performance of applied modulation-based free space optic system using a coupler-based delay line filter. Aside this, the recreation results are examined and natter about the dependent of quality factor, bit error rate (BER), and eye outline of various FSO parameters pertaining to the same. The outcomes of the research bestow on the recreation results acquired for quality factor and BER against various conditions with respect to the both adjustment techniques and PSK offers better execution.

Single-Event Transients in an IEEE 802.15.4 RF Receiver for Wireless Sensor Networks.

This paper presents a procedure to analyse the effects of radiation in an IEEE 802.15.4 RF receiver for wireless sensor networks (WSNs). Specifically, single-event transients (SETs) represent one of the greatest threats to the adequate performance of electronic communication devices in high-radiation environments. The proposed procedure consists in injecting current pulses in sensitive nodes of the receiver and analysing how they propagate through the different circuits that form the receiver. In order to perform this analysis, a Complementary Metal Oxide Semiconductor (CMOS) low-IF receiver has been designed using a 0.18 μm technology from the foundry UMC. In order to analyse the effect of single-event transients in this receiver, it has been studied how current pulses generated in the low-noise amplifier propagate down the receiver chain. The effect of the different circuits that form the receiver on this kind of pulse has been studied prior to the analysis of the complete receiver. First, the effect of SETs in low-noise amplifiers was analysed. Then, the propagation of pulses through mixers was studied. The effect of filters in the analysed current pulses has also been studied. Regarding the analysis of the designed RF receiver, an amplitude and phase shift was observed under the presence of SETs.

New Interpretation of X-ray Photoelectron Spectroscopy of Imidazolium Ionic Liquid Electrolytes Based on Ionic Transport Analyses.

We reported a new perspective on the correlation between the electronic structure of an ionic liquid (IL)-based electrolyte probed by X-ray photoelectron spectroscopy and the transport properties analyzed by impedance spectroscopy. We highlighted the core level chemical shifts of 1-hexyl-3-methylimidazolium (bis(trifluoromethanesulfonyl)imide) (C1C6ImTFSI), 1-hexyl-3-methylimidazolium bis(fluorosulfonyl)imide (C1C6ImFSI), and 1-hexyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide (C1C1C6ImTFSI) laden with LiTFSI salt and vinylene carbonate (VC) or fluoroethylene carbonate (FEC) with regard to the transport properties of cations and anions. We pointed out based on detailed binding energy shift analyses a clear effect of the anion on the local organization of Li+ ions. The significant peak shift in the case of C1C6ImTFSI laden with LiTFSI corroborates the formation of [Li(TFSI)2]- complexes. On the contrary, the lower amplitude of the binding energy shift of C1C6ImFSI for both anion- and cation-related peaks indicates that the electronic distribution around the cation and the anion is not affected when the LiTFSI salt is added, which plays a strong role in the ion dynamics (lower viscosity) of the electrolyte. The X-ray photoelectron spectroscopy (XPS) result supports the preponderant role of imidazolium ionic liquid based on FSI anion to form an electrolyte less prone to form ionic complexes. The methylation of the imidazolium cation contributes to the reduction of the interaction between the C1C1C6Im cation and TFSI anion, while additives VC and FEC contribute to the change of the alkyl configuration in C1C6Im cation, leading to the modification of the macroscopic properties of the ILs.