Analysis and Evaluation of Periodic Medium Structure on Shielding Effectiveness

Electromagnetic metamaterials/metasurfaces have been widely concerned by researchers because of their rich resonance properties. Metamaterial absorbers with single resonance mode and narrow bandwidth are often used in sensing fields. However, the development of such metamaterial absorbers by optimizing the dielectric layer structure has not received much attention. In this paper, a metamaterial absorber containing dielectric layers of the same thickness (PMMA and STO dielectric layers) are proposed and confirmed. At room temperature, an individual absorption peak is excited, and the single resonance mode and narrow bandwidth characteristic is obtained (resonant frequency is 266.14THz, peak value is 0.902, the FWHM is 1.1THz). The amplitude and resonance frequency of the metamaterial sample can be controlled by changing the thickness of PMMA or STO dielectric layers. An equivalent LC resonant circuit is constructed and used to interpret the relationship between the resonant frequency and the thickness of the dielectric layer. In further experimental measurements, the metamaterial sample was placed in an environment with a gradual change in temperature. Two metamaterial units with the same dielectric layer structure strategy are also proposed and simulated, and similar resonance behaviors can also be excited by these two new metamaterial units. The results show that the absorptive properties of the metamaterial sample show remarkable repeatability in the process of temperature increase and temperature decrease. Therefore, based on the properties of single resonance mode, narrow bandwidth, and reversibility, the metamaterial sample has the potential to be used in smart packaging sensing.

Ammonia-oxidizing archaea and bacteria (AOA, AOB) catalyze the first and rate-limiting step of nitrification. To examine their differential responses to the wetting of dry and salty arid soil, AOA and AOB amoA genes (encoding subunit A of the ammonia monooxygenase) and transcripts were enumerated in dry (summer) and wet (after the first rainfall) soil under the canopy of halophytic shrubs and between the shrubs. AOA and AOB were more abundant under shrub canopies than between shrubs in both the dry and wetted soil. Soil wetting caused a significant decrease in AOB abundance under the canopy and an increase of AOA between the shrubs. The abundance of the archaeal amoA gene transcript was similar for both the wet and dry soil, and the transcript-to-gene ratios were < 1 independent of niche or water content. In contrast, the bacterial amoA transcript-to-gene ratios were between 78 and 514. The lowest ratio was in dry soil under the canopy and the highest in the soil between the shrubs. The results suggest that the AOA are more resilient to stress conditions and maintain a basic activity in arid ecosystems, while the AOB are more responsive to changes in the biotic and abiotic conditions.

The problem of scattered and transmitted electromagnetic wave distortion by random rough ground surfaces can be reduced by using a lightweight dielectric matching layer. For mine detection applications, it is essential for this layer to be lightweight, low loss, readily conformable, and adaptable to different soil types. Arrays of metal-coated plastic spheres act as lossless artificial dielectrics with impedance determined by the volume packing fraction. By controlling the thickness of insulator surrounding each sphere, a close-packed array with the dielectric properties of soil can be created inside a compliant rolling bag that will conform to the rough surface of the ground. Since this artificial dielectric is matched to the soil, the ground surface interface is 'softened', without an abrupt transition from soil to air. Signals transmitted and received by GPR antennas immersed in the artificial dielectric within the bag will not be corrupted by ground surface clutter. Alternatively, an artificial dielectric layer on the ground with a planar air interface could be used to ensure that the surface reflection is a constant, well-calibrated signal. Computational models indicate complete removal of the ground clutter, even with occasional gaps between the artificial dielectric and the ground. Experimental studies with swept-frequency measurements and impulse GPR indicate that using this dielectric layer matching to a rough loamy soil ground surface is results in signals that are practically indistinguishable from those of an equivalent layer of the same type of soil.

Electrostatic flexible film based smart window: Optical design, performance and residual charge investigation

The disappearance of EPTC (ethyl N,N-di-n-propylthiolcarbamate) from soils was studied by steam distilling the remaining EPTC from the soil samples and analyzing the distillates. The most important factor affecting the loss of EPTC from soil was the amount of moisture in the soil. During the first 15 minutes after spraying on the soil surface, 20% of the applied EPTC disappeared from dry soil, 27% from moist soil and 44% from wet soil. The loss was 23, 49, and 69% after one day and 44, 68, and 90% after six days on dry, moist, and wet soils, respectively. No significant loss of EPTC occurred the first few hours after applying granular EPTC to dry soil or soil containing 4 to 6% moisture, but on soil at 15% moisture the loss from granules was 60% in two hours. There appeared to be a critical moisture level for each soil, above which large losses of EPTC occurred after application to the surface or after shallow incorporation. Depth of incorporation was the second most important factor in EPTC loss from soils. Incorporation to at least 2 to 3 inches was necessary to prevent large losses of EPTC when light rain or sprinkler irrigation followed treatment. EPTC was lost at a faster rate on sunny days than cloudy days. Increasing the temperature from 32 to 60 F, increased the rate of EPTC vaporization from moist soil but had no effect on the loss from dry soil.

The transmission properties of one-dimensional photonic crystal consisting superconducting and dielectric material has been investigated theoretically by transfer matrix method (TMM). The transmission spectra obtained by simulation of superconductor photonic crystal shows Fano resonance line profile. The Fano resonance observed in transmission spectra is the function of the thickness of constituent layers, number of periods, and temperature of superconductor. The maxima and minima of Fano resonance can be changed by varying thickness of superconductor and dielectric layers. Increase in thickness of superconductor layer increases the maxima of Fano resonance towards 100 % transmittance, while minima of Fano resonance tends towards zero transmittance. The gradient between maxima and minima of the Fano resonance decreases with increasing the thickness of the superconductor layer while the gradient of Fano resonance increases with increase in thickness of dielectric layer. Increasing the thickness of dielectric layer decreases the maxima of Fano resonance. The position of Fano resonance can be tuned over a definite frequency range by varying temperature of the superconductor layer.

Multilayer capacitors consist of multiple, often hundreds of capacitors connected in parallel to maximize volumetric efficiency. As the dielectric and electrode layer thicknesses are scaled down, microstructural imperfections become increasingly influential on the device electrical performance. Specifically, the presence of nonplanar and discontinuous electrodes can lead to local field enhancements while the relative morphologies of two adjacent electrodes determine variations in the local dielectric thickness. To study the effects of electrode morphologies, an analytical approach is taken to calculate the field enhancement and leakage current with respect to an ideal parallel‐plate capacitor. It is shown that the electrode roughness causes the leakage current to increase with respect to that of the ideal flat parallel‐plate capacitor. To further include the effects of local curvature on electric field enhancements, finite element methods are used to calculate field distributions within capacitor structures containing rough interfaces and porosity. In these simulations, the effects of electrode pore diameters, dielectric layer thickness, and the amplitude and wavelength of the electrode roughness are studied.

The ferroelectric polarization switching in ferroelectric hafnium zirconium oxide (Hf0.5Zr0.5O2, HZO) in the HZO/Al2O3 ferroelectric/dielectric stack is investigated systematically by capacitance-voltage and polarization-voltage measurements. The thickness of dielectric layer is found to have a determinant impact on the ferroelectric polarization switching of ferroelectric HZO. A suppression of ferroelectricity is observed with thick dielectric layer. In the gate stacks with thin dielectric layers, a full polarization switching of the ferroelectric layer is found possible by the proposed leakage-current-assist mechanism through the ultrathin dielectric layer. Theoretical simulation results agree well with experimental data. This work clarifies some of the critical parts of the long-standing confusions and debating related to negative capacitance field-effect transistors (NC-FETs) concepts and experiments.

Corn is a sustainability crop commodity that has the potential to contribute to the growth and progress of the agricultural industry. The objective of this research is to examine the various factors that impact maize production on dry and wet soils, compare the relationship between maize yield and income on dry and wet lands, and assess the sustainability of maize in the Mekikis village of Purwoasri district. Descriptive and statistical analyzes (double regression analysis), enterprise feasibility analysis, and differential tests of averages (independent sample t-test) comprise the method of analysis in this study. Nonproportional stratified random sampling was utilized to obtain a sample size of 64 respondents, 32 of whom were wetland farmers and 32 of whom were dry land farmers. The attributes of the farmers who participated in the research encompassed gender, age, most recent educational attainment, primary occupation, family count, land area ownership, and land area. The results of the double linear regression analysis indicate that both the land area and labor force significantly impact maize production on moist soil. The impact of various factors such as land area, seeds, inorganic fertilisers, and pesticides on maize production in arid soil is substantial. The results of the independent sample t-test indicate a statistically significant difference between the yield and income of maize grown in moist and dry soils. specifically, the profit on maize is Rs. 1,624,218,099.94, while the yield on maize in dry soils is 1,899.87 per kilogramme. The usability analysis of maize indicates that the R/C ratio differs when the soil is moist versus when it is dry.

Experimental investigation of thermal and moisture behaviors of wet and dry soils with buried capillary heating system

Mastication of woody shrubs is used increasingly as a management option to reduce fire risk at the wildland–urban interface. Whether the resulting mulch layer leads to extreme soil heating, if burned, is unknown. We measured temperature profiles in a clay loam soil during burning of Arctostaphylos residues. Four mulch depths were burned (0, 2.5, 7.5 and 12.5 cm), spanning typical conditions at forested sites in northern California with dense pre-mastication shrub cover. Two soil moisture contents were compared at each fuel depth to simulate spring prescribed burning (moist soil) and late-season wildfire (dry soil). Maximum temperatures reached 600°C on the surface of dry soils and were 100–200°C lower for moist soil. Heating was extensive in dry soil for the two deepest mulch depths, exceeding the lethal threshold for plants (60°C) for a minimum of 7 h throughout the 10-cm soil profile. Minimal heat pulse was found with less mulch. Moist soil also dampened heat penetration; peak temperatures exceeded 60°C only to 2.5 cm in the soil profile for all but the deepest mulch layer. No adverse effects of burning on water repellency were found in dry or moist soil. The potential for biological damage from soil heating during fire exists following mastication, particularly in dry soil with a mulch depth of 7.5 cm or greater. Field projections indicate that up to one-fourth of treated areas with dense pre-mastication vegetation would surpass lethal soil temperatures during a surface wildfire.

Redistribution of water within plants could mitigate drought stress of roots in zones of low soil moisture. Plant internal redistribution of water from regions of high soil moisture to roots in dry soil occurs during periods of low evaporative demand. Using minirhizotrons, we observed similar lifespans of roots in wet and dry soil for the grapevine 'Merlot' (Vitis vinifera) on the rootstock 101-14 Millardet de Gramanet (Vitis riparia x Vitis rupestris) in a Napa County, California vineyard. We hypothesized that hydraulic redistribution would prevent an appreciable reduction in root water potential and would contribute to prolonged root survivorship in dry soil zones. In a greenhouse study that tested this hypothesis, grapevine root systems were divided using split pots and were grown for 6 months. With thermocouple psychrometers, we measured water potentials of roots of the same plant in both wet and dry soil under three treatments: control (C), 24 h light + supplemental water (LW) and 24 h light only (L). Similar to the field results, roots in the dry side of split pots had similar survivorship as roots in the wet side of the split pots (P = 0.136) in the C treatment. In contrast, reduced root survivorship was directly associated with plants in which hydraulic redistribution was experimentally reduced by 24 h light. Dry-side roots of plants in the LW treatment lived half as long as the roots in the wet soil despite being provided with supplemental water (P < 0.0004). Additionally, pre-dawn water potentials of roots in dry soil under 24 h of illumination (L and LW) exhibited values nearly twice as negative as those of C plants (P = 0.034). Estimates of root membrane integrity using electrolyte leakage were consistent with patterns of root survivorship. Plants in which nocturnal hydraulic redistribution was reduced exhibited more than twice the amount of electrolyte leakage in dry roots compared to those in wet soil of the same plant. Our study demonstrates that besides a number of ecological advantages to protecting tissues against desiccation, internal hydraulic redistribution of water is a mechanism consistent with extended root survivorship in dry soils.

The complex interactions between soil moisture and precipitation are difficult to observe, and consequently there is a lack of consensus as to the sign, strength, and location of these interactions. Inconsistency between soil moisture–precipitation interaction studies can be attributed to a multitude of factors, including the difficulty of demonstrating causal relationships, dataset differences, and precipitation autocorrelation. The purpose of this study is to explore these potential confounding factors and determine which are most important for consideration when assessing statistical coupling between soil moisture and precipitation. Soil moisture is assessed via three remote sensing datasets: the Advanced Microwave Scanning Radiometer for Earth Observing System, the Tropical Rainfall Measuring Mission Microwave Imager, and the Essential Climate Variable Soil Moisture. Estimates of soil moisture are coupled with afternoon thunderstorm events identified by the Thunderstorm Observation by Radar (ThOR) algorithm, and dry soil or wet soil preferences for convection initiation are determined for over 16 000 thunderstorm events between 2005 and 2007. Differences in soil moisture datasets were found to have the largest impact with regard to determining wet or dry soil preferences. Precipitation autocorrelation is prevalent in the data; however, precipitation autocorrelation did not influence the results with regard to dry or wet soil preferences. Consideration of the convective environment (i.e., weakly or synoptically forced) did result in significant differences in wet/dry soil preference, but only for certain soil moisture datasets. The results suggest that observation-driven soil moisture–precipitation interaction studies should both consider the convective environment and implement multiple soil moisture datasets to assure robust results.

We investigate the characterization of defect modes in one-dimensional ternary symmetric metallo-dielectric photonic crystal (1DTSMDPC) band-gap structures. We consider the defect modes for symmetric model with respect to the defect layer. We demonstrate re∞ectance with respect to the wavelength and its dependence on difierent thicknesses and indices of refraction of dielectric defect layer, angle of incidence and number of periods for both transverse electric (TE) and transverse magnetic (TM) waves. Also, we investigate properties of the defect modes for difierent metals. Our flndings show that the photonic crystal (PC) with defect layer, made of two dielectrics and one metallic material, leads to difierent band-gap structures with respect to one dielectric and one metallic layer. There is at least one defect mode when we use dielectric or metallic defect layer in symmetric structure. And, the number of defect modes will be increased by the enhancement of refractive index and thickness of dielectric defect layer.

Airborne soil moisture measurement is based on the difference between natural terrestrial gamma radiation flux measured for comparatively wet and dry soils. The presence of moisture in the soil causes an effective increase in the soil density resulting in an increased attenuation of the gamma flux for relatively wet soil and a correspondingly lower flux at the ground surface. As part of the FIFE experiment, natural terrestrial gamma radiation data over a network of 24 flight lines were collected. The data acquisition procedure was designed to accumulate and store spectral radiation data along a flight line from which estimates of soil moisture could be computed. Ground-based soil moisture measurements were used to make a one-time calibration of the natural terrestrial radioisotope signal over the flight line network. A time-series of airborne soil moisture measurements (to a depth of 20 cm) was compared to an extensive, independent data set of ground-based soil moisture measurements. Estimates for flight line segments were found to have an average RMS error of approximately 2.5 % soil moisture (Peck et al., 1990).