Amplitude Phase Shift Research Articles

Dynamic measurement of moisture content using microwaves for moisture evaluation of agricultural products

AbstractThis paper describes a dynamic measurement method using correlations between phase and amplitude changes of microwaves for the moisture content of agricultural products such as rice and wheat. The proposed method does not require the value of the bulk density and/or the mass of the target. Static and dynamic measurements of rice with different moisture contents were performed. The results of the dynamic measurements were in close agreement with those of the static measurements. The ratio of the amplitude change and phase shift is linearly dependent on the moisture content of rice for both the static and dynamic measurements. Furthermore, it is possible to measure wrapped silage samples with a high moisture content directly. To optimize the measurement frequency, the relationships between the moisture content and phase–amplitude correlation was evaluated. As a result, an optimized frequency was obtained. The proposed method is available under conditions such as the range of moisture content from 10 to 80% with one optimized frequency. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

A Soft Decoding Algorithm with Hard Decision Boundary Factor for High-Order M-APSK Signal

High-order amplitude phase shift keying is adopted in the latest digital satellite broadcasting system, which presents new challenges to the design of a receiver demodulation scheme. This study focuses on the soft decision decoding algorithm. Traditionally, maximum likelihood soft decision based on log likelihood ratio estimation is often used as a decoding scheme. Accordingly, a soft decision algorithm based on hard decision boundary is designed and the corresponding soft decision estimation formula is derived. Numerical analytical results show that the proposed soft decision algorithm can improve the error performance of a system and substantially reduce the complexity of implementation.

Non‐destructive prediction of forage crop moisture contents using microwave transmitted signals with a microstrip transmission line sensor

AbstractThis paper describes a non‐destructive method for using microwave transmitted signals to measure the moisture content of silage wrapped with plastic films. To collect measurements by a vector network analyzer, each bag of silage was placed on a microstrip transmission line without destruction of the films. Both rye and corn were tested. Significant linear relationships between the amplitude change (ΔA) and phase shift (Δφ) were obtained except for with fully dried corn, and the corresponding R2 values between ΔA and Δφ were 0.8 or greater. The slopes, which represent the ratio of phase shift to amplitude change (Δφ–ΔA ratio), depended on the frequency and moisture content. R2 values between the Δφ–ΔA ratio and moisture content of rye and corn were greater than 0.8 at the frequency of 3.6 GHz or above except for with fully dried corn samples. At 3.6 GHz, significant linear relationships between the Δφ–ΔA ratio and moisture content were obtained for rye and corn. Furthermore, the slope and intercept of the linear regression line between the Δφ–ΔA ratio and moisture content of rye were not significantly different from those of corn. These results illustrate the potential of the non‐destructive moisture content measurement method with microwave transmitted signals for silage materials with high moisture contents.

Amplitude Delta Factors and Phase Shifts of Tidal Waves for the Earth with the Ocean on the Territory of Russia

The results of the calculation of the amplitude delta factors and phase shifts of semidiurnal and diurnal tidal waves for a rotating self-gravitating ellipsoidal inelastic Earth with the ocean are presented, and the method used to calculate them is briefly described. The maps of distribution of the considered tidal parameters are constructed for the M2 and K1 waves over the territory of Russia; the zones with extreme and generally accepted values are identified. A discussion of the revealed features of the distribution of the amplitude factors and phase shifts on the territory of the Russian Federation is presented.

Limits on Groundwater‐Surface Water Fluxes Derived from Temperature Time Series: Defining Resolution‐Based Thresholds

AbstractHeat as a tracer is frequently used to quantify Darcy fluxes across the groundwater‐surface water interface. Often quantified through the analysis of diurnal or annual periodic temperature signals, these temperature time series methods rely on the advective transport of heat by flowing water perturbing the periodic conducted heat signal. Multiple methodologies have been developed that rely on temperature time series data collected from at least two unique depths a set distance apart. However, the lower limits at which these methods can no longer reliably quantify a Darcy flux are not well established. To examine these lower limits, synthetic temperature time series data were generated using a numerical model for various combinations of head gradients, sensor spacing, and thermal properties of the sediment. Darcy fluxes were subsequently quantified using the combined method and directly compared to prescribed Darcy fluxes. The dimensionless Péclet number, representing the ratio of advective to conductive heat flux, was used to establish threshold values at which the combined amplitude ratio and phase shift method was no longer able to reliably quantify a Darcy flux. The lowest recharge Darcy flux that can be quantified ranges from 0.07 to 0.2 m/day, dependent on the resolution of the sensor used to collect data, a narrower range than previously reported. When transitioning to a field setting, where the accuracy of Darcy fluxes is not known, a newly developed relationship between the true and inferred Péclet numbers can be used to evaluate quantified Darcy fluxes for accuracy.

Analysis of EXAFS Spectra of Crystalline Copper using Classical Anharmonic Correlated Einstein Model

In this work, the temperature dependence of extended X-ray absorption fine structure (EXAFS) of the crystalline copper structure was calculated and analyzed using the anharmonic correlated Einstein model and the classical statistical theory. The thermodynamic parameters of a system are derived from an anharmonic effective potential that has taken into account the influence of all nearest neighbors of absorbing and backscattering atoms in the crystal lattice with thermal vibrations, where the Morse potential is assumed to characterize the interactions between each pair of atoms and the function of anharmonic EXAFS spectra presented in terms of the cumulant expansion up to the fourth-order. Analytical expressions for the first four cumulants and their contribution to amplitude reduction and phase shift obtained in the simple form of the mean-square relative displacement or the correlated Einstein frequency. The numerical results for crystalline copper were in good agreement with those obtained by the other theoretical procedures and experiments at several temperatures. The analytical results show that this calculation model is useful to reduce measurement and data analysis of experimental EXAFS spectra.

Target detection modeling against the clutter background of the radar with quasi-continuous mode of transmission and reception of signals with pseudorandom law of amplitude-phase shift keying

This paper presents the mathematical model of moving target detection against the clutter background of the radar with quasi-continuous mode of transmission and reception of signals with pseudorandom law of amplitude-phase-shift keying. The modeling results of the optimal pair of “signal - processing method” research, which provides the maximum range of target detection under noise conditions, are presented.

Developing predictive models for analysis the heat transfer in sinusoidal wavy channels

In this work, empirical correlations were proposed to accurately estimate the heat transfer and pressure drop for water flow in sinusoidal wavy channels. The artificial intelligence techniques such as artificial neural network (ANN) and genetic algorithm (GA) were applied to develop the correlations. The experimental data related to the Nusselt number (Nu) and pressure drop (ΔP) in the wavy channels with various geometries were collected for the modeling. The independent variables are Reynolds number (Re) and main geometrical parameters including amplitude ratio (b/H), phase shift (φ), and number of waves (Nw). The results indicate that the ANN is a suitable technique to develop correlations for predicting thermal and flow characteristics in heat exchangers with wavy channels.

Performance Comparison of 2 × 20 Gbit/s-40 GHz OFDM Based RoFSO Transmission Link Incorporating MDM of Hermite Gaussian Modes Using Different Modulation Schemes

The shortage of radio frequency spectrum for wireless communication networks has been addressed by using millimeter wave (mm-wave) transmission in optical-wireless and Radio over Free space optics (RoFSO) links. This work reports the performance comparison of 4-level quadrature amplitude modulation (QAM) and phase shift keying (PSK) based orthogonal frequency division multiplexing-RoFSO transmission link under the effect of atmospheric turbulence. Two independent 20 Gbit/s-40 GHz information signals are transmitted over distinct Hermite Gaussian modes (HG01 and HG03) under heavy fog conditions using different modulation schemes over a link range of 2000 m. The results presented show that 4-QAM scheme performs better as compared to 4-PSK scheme. Also, we report the modal decomposition of the transmitted channels in terms of linear polarized modes at the receiver terminal. The proposed work can be used for realizing long-reach high-capacity bandwidth efficient information transmission links.

Modeling Attenuation of Diffusive-Viscous Wave Using Reflectivity Method

Seismic waves in earth materials are subject to attenuation and dispersion in a broad range of frequencies. The commonly accepted mechanism of intrinsic attenuation and dispersion is the presence of fluids in the pore space of rocks. The diffusive-viscous model was proposed to explain low-frequency seismic anomalies related to hydrocarbon reservoirs. But, the model is only a description of compressional wave. In this work, we firstly discuss the extended elastic diffusive-viscous model. Then, we extend reflectivity method to the diffusive-viscous medium. Finally, we present two numerical models to simulate the attenuation of diffusive-viscous wave in horizontal and dip multi-layered media compared with the results of viscoelastic wave. The modeling results show that the diffusive-viscous wave has strong amplitude attenuation and phase shift when it propagates across absorptive layers.

Field Experiments of Hyporheic Flow Affected by a Clay Lens

As a typical water exchange of surface water and groundwater, hyporheic flow widely exists in streambeds and is significantly affected by the characteristics of sediment and surface water. In this study, a low-permeability clay lens was chosen to investigate the influence of the streambed heterogeneity on the hyporheic flow at a river section of the Xin’an River in Anhui Province, China. A 2D sand tank was constructed to simulate the natural streambed including a clay lens under different velocity of surface water velocity. Heat tracing was used in this study. In particular, six analytical solutions based on the amplitude ratio and phase shift of temperatures were applied to calculate the vertical hyporheic flux. The results of the six methods ranged from −102.4 to 137.5 m/day and showed significant spatial differences. In view of the robustness of the calculations and the rationality of the results, the amplitude ratio method was much better than the phase shift method. The existence of the clay lens had a significant influence on the hyporheic flow. Results shows that the vertical hyporheic flux in the model containing a clay lens was lower than that for the blank control, and the discrepancy of the hyporheic flow field on both sides of the lens was obvious. Several abnormal flow velocity zones appeared around the clay lens where the local hyporheic flow was suppressed or generally enhanced. The hyporheic flow fields at three test points had mild changes when the lens was placed in a shallow layer of the model, indicating that the surface water velocity only affect the hyporheic flow slightly. With the increasing depth of the clay lens, the patterns of the hyporheic flow fields at all test points were very close to those of the hyporheic flow field without a clay lens, indicating that the influence of surface water velocity on hyporheic flow appeared gradually. A probable maximum depth of the clay lens was 30 to 40 cm, which approached the bottom of the model and a clay lens buried lower than this maximum would not affect the hyporheic flow any more. Influenced by the clay lens, hyporheic flow was hindered or enhanced in different regions of streambed, which was also depended on the depth of lens and surface water velocity. Introducing a two-dimensional sand tank model in a field test is an attempt to simulate a natural streambed and may positively influence research on hyporheic flow.

Capillary Effects on Groundwater Response to Earth Tides

AbstractThe response of unconfined aquifers to Earth's solid tides (Earth tides) has been used to study a number of hydrogeological, environmental, and ecological processes. The traditional interpretation of such responses has been based on a model that assumes free flow of groundwater to the water table, even though capillary effects have long been recognized to influence the response of coastal aquifers to ocean tides. Here we study the capillary effect on the response of unconfined aquifers to Earth tides, using a numerical procedure that couples groundwater flow and poroelastic strain in both the saturated and the unsaturated zones. We show that when the water table rises to the surface and the capillary zone disappears, the predicted tidal response is identical to that predicted by the traditional model. But when the capillary zone is present when the water table falls below the surface, the predicted amplitude ratio and phase shift depart notably from those predicted by the traditional model. We apply the model to a field case where large seasonal changes of tidal response have been documented. We show that the large seasonal changes in the tidal response may be due to the change of the water table from a capillary‐affected state to a capillary‐free state when the water table rises annually to the ground surface. Thus, the omission of the capillary effects in the interpretation of the response of unconfined aquifers to Earth tides may lead to incorrect inference of subsurface processes and properties.

Augmentation of Spectral Efficiency using APSK in FBMC to Assess High Data Rate

There are various techniques which have been developed to improvise the modulation technique exploited in the system which were intended to enhance the data rate and bandwidth of the 5G network. Various researchers worked on OFDM modulation technique in order to enhance the efficiency as it is successfully working on 4G networks. Although utilization of OFDM in 5G networks will not provide the expected outcomes due to some flaws. This paper proposed a system that induced FBMC (Filter Bank Multi-Carrier) modulation technique which is capable of delivering higher spectral efficiency than OFDM. Proposed method employed APSK (Amplitude Phase Shift Modulation) for the modulation of sub carriers. The idea of implementing APSK in FBMC is to optimize the peak to average power ratio and also reduces bit error rate. The techniques proposed in the system, aimed to achieve high efficiency in terms of data rate and bandwidth with less power consumption. By using MATLAB all the simulations will be performed to analyze the results of spectral efficiency in terms of BER vs Eb/No (SNR) and power spectral density.

One dimensional photonic crystal as an efficient tool for in-vivo optical sensing of neural activity

In this paper, we recorded optically the neural/neuromuscular activity of alive worm via phase-sensitive measurement while stimulating it optically using infrared laser. By supporting Tamm plasmon mode, our fabricated multilayer structure of Glass/(TiO2/SiO2)12/Au was used as a sensing platform. By fixing an earth worm to the gold side of the structure and using open optic measurements, the amplitude ratio (Ψ) and phase shift (Δ) of reflections under s- and p-polarized incident lights have been recorded for different frequencies and pulse duration of IR laser. By increasing the pulse duration to 17 m s, Δ and Ψ values of Tamm Plasmon Polariton resonance for different frequencies have been splitted considerably in a regular trend. We hope that the combination of plasmonics and Tamm plasmon mode can open new insights into non-invasive neural/neuromusular stimulation and recording.

8-port homodyne detection of optical fields using IQ demodulation

A phase-sensitive detection scheme for optical fields is described, which allows for the simultaneous measurement of orthogonal field quadratures. The recent achievement of -radian cross-phase shifts between a single photon and a second light field has opened the door to quantum computing protocols which utilize photonic quantum bits. Optical phase measurements play an integral role in these schemes. The detection scheme presented here was designed to measure such transient phase shifts of a laser field as it interacts with another light field through a cloud of laser-cooled Rb atoms. In place of conventional spatial interferometry, which is very sensitive to mechanical instabilities, the scheme utilizes beat-note interferometry to improve on the robustness of the measurement. Beat-note interferometry serves to map a signal from a THz-frequency carrier onto a radio-frequency carrier. A variant of 8-port optical homodyne detection, the scheme then uses IQ demodulation, a well-established technique in communications engineering, to extract amplitude information for both the in-phase (I) and quadrature-phase (Q) components of the radio-frequency signal. This IQ data can then be used to extract any amplitude variation and/or phase shifts of the original THz-frequency optical field. The technique is illustrated here by simultaneously measuring the absorption and dispersion experienced by an optical beam as it passes through a cloud of laser-cooled atoms, which have been prepared in a state of electromagnetically-induced transparency. A thorough characterization of the measurement is presented, which identifies the dominant noise sources and illustrates the utility of IQ demodulation in eliminating noise. This scheme has been used to measure rad phase shifts on nanosecond time scales.

High-order EXAFS cumulants of diamond crystals based on a classical anharmonic correlated Einstein model

The temperature dependence of high-order cumulants in extended X-ray absorption fine structure (EXAFS) of the diamond crystal structure was calculated and analyzed on the basis of the anharmonic correlated Einstein model and the classical statistical method. Thermodynamic parameters of a system were derived from the high-order anharmonic effective potential, where the Morse potential was used to characterize the interaction between each pair of atoms in expansion up to the fourth order. Analytical expressions for the first four cumulants and their contribution to amplitude reduction and phase shift were obtained in the simple form of the mean-square relative displacement or the correlated Einstein frequency. Numerical results for crystalline germanium were in good agreement with experimental values and values calculated by the quantum statistical method and other methods, especially with the values in the high-temperature range. The analytical results show that this method is useful to reduce measurement and data analysis of experimental EXAFS spectra.

RHBD Techniques to Mitigate SEU and SET in CMOS Frequency Synthesizers

This paper presents a thorough study of radiation effects on a frequency synthesizer designed in a 0.18 μ m CMOS technology. In CMOS devices, the effect of a high energy particle impact can be modeled by a current pulse connected to the drain of the transistors. The effects of SET (single event transient) and SEU (single event upset) were analyzed connecting current pulses to the drains of all the transistors and analyzing the amplitude variations and phase shifts obtained at the output nodes. Following this procedure, the most sensitive circuits were detected. This paper proposes a combination of radiation hardening-by-design techniques (RHBD) such as resistor–capacitor (RC) filtering or local circuit-redundancy to mitigate the effects of radiation. The proposed modifications make the frequency synthesizer more robust against radiation.

Differential 8-APSK monolithically integrated dual-EML transmitter for flexible coherent PONs

We experimentally demonstrate a simultaneous amplitude and phase modulation of a monolithically integrated dual electro-absorption modulated laser. The proposed technique combines a 4-ary direct phase modulation with a two-level amplitude modulation obtaining an 8-ary amplitude phase shift keying external-modulator-free transmitter (Tx). Its performance was tested up to 7.5 Gb/s in a 25 km single-mode fiber link with intradyne coherent detection. A receiver sensitivity of −42.5 dBm was achieved at a forward error correction limit bit error ratio =4×10−3. The results show that the proposed system can be an efficient flexible Tx for next-generation passive optical networks.

Method for estimation of solar, geomagnetic, and atmospheric contributions to 27-day component of peak electron density

Abstract The study suggests a new method for estimation of the solar, geomagnetic, and atmospheric contributions to 27-day component of peak electron density. For our analysis, we calculated complex amplitudes of 27-day components filtered from the data sets of peak electron density and indices of solar and geomagnetic activity. The use of complex amplitudes takes into account both the amplitude ratios and phase shifts (time delays between the 27-day components) within linear regressions. In this study we use the coefficients of determination for linear regressions to estimate the solar and geomagnetic contributions to the ionospheric variations. The coefficient of determination represents the proportion of the total variation in the dependent variable (ionospheric variations) that is explained by the independent variables (variations in solar and geomagnetic indices). Comparison with other studies showed that, apparently, the contribution estimation strongly depends on the filter bandwidth and the method for calculating the correlation coefficient. The choice of the optimal method and the filter bandwidth is open to question.

Study on aquifer hydraulic properties using tidal response method for future groundwater development

The hydraulic properties of an island’s aquifers were studied using a tidal response method. Groundwater is the principal water resource on the studied island, and the investigations of the aquifer for future groundwater development are ongoing. The method consists of three parts: observations of groundwater levels at paired near-shore and relatively inland sites affected by the same ocean tide, decompositions of the collected groundwater time series to yield isolated tidal components, and application of basic formulas describing propagation of groundwater-level oscillations in aquifers for determining hydraulic parameters. The observations require only auto-logging groundwater-level meters that are commonly used these days. Employed were two decomposition techniques that are easy to implement using only the built-in functions of spreadsheet software. Digital high-pass filtering was used to separate the tidal components of semidiurnal and diurnal periods from longer-period components prior to the following isolation of tidal constituents. Basic formulas for the Fourier transform were used to isolate one tidal constituent with a specific period. The isolation of one tidal constituent helps to reduce errors in the hydraulic parameter calculations based on formulas using the amplitude attenuation and phase shift of sinusoidal oscillations of the groundwater level. The calculation of aquifer hydraulic parameters can also be done directly on a spreadsheet. The derived aquifer hydraulic parameters compared well with those that were previously reported based on a pumping test conducted on the same island. The results are now used as a basis for further investigation of sustainable groundwater development on the island.