Miniaturized CSRR TAG Antennas for 60GHz Applications

In this paper, a novel approach to design an antenna for a transponder inradio frequency identification (RFID) is proposed. This approach is based onusing a slot-ring antenna with a coplanar waveguide excitation integratedantennas in silicon technology. The RFID frequency chosen is the worldwideavailable free 60-GHz band .The structure is simulated by using ComputerSimulation Technology (CST). The antenna size is 1.5 × 1.3 mm2. Thisproposed antenna presents a gain about 3.82 dB which means a possibility toincrease the readable range.DOI:http://dx.doi.org/10.11591/ijece.v4i1.472

Impact of crosstalk into high resistivity silicon substrate on the RF performance of SOI MOSFET

Crosstalk propagation through silicon substrate is a serious limiting factor on the performance of the RF devices and circuits. In this work, substrate crosstalk into high resistivity silicon substrate is experimentally analyzed and the impact on the RF behavior of silicon-on-insulator (SOI) MOS transistors is discussed. The injection of a 10 V peak-to-peak single tone noise signal at a frequency of 3 MHz ( fnoise) generates two sideband tones of *−56 dBm separated by fnoise from the RF output signal of a partially depleted SOI MOSFET at 1 GHz and 4.1 dBm. The efficiency of the introduction of a trap-rich polysilicon layer located underneath the buried oxide (BOX) of the high resistivity (HR) SOI wafer in the reduction of the sideband noise tones is demonstrated. An equivalent circuit to model and analyze the generation of these sideband noise tones is proposed

Analysis of Plane Waves Spectra in a Weakly-Disturbed Flat Reverberation Chamber by Information Theory Criteria

This work aims to present the impact of disturbing the stationary modes in a rectangular-shaped reverberation chamber by small-dimensioned stirrers. The study focuses on plane wave’s modeling of the electric field inside a flat cavity using information theory criteria. The emphasis is on anisotropy of the number of plane-waves distribution in the cavity and a strong increase near stirrers. The distributions of the plane wave spectra are studied for a set of reverberation chamber configurations at frequencies close to and far superior to the lowest usable frequency

Performance of evapotranspiration models for a maize agro-ecosystem : from bare soil to maximum coverage in irrigated and rainfed conditions

To assure an efficient management and planning of irrigation water resources, an accurate computation of actual evapotranspiration (ET) from cropped surfaces is needed. ET models can be classified in two categories: \u201cdirect\u201d methods, based on the original Penman-Monteith (P-M) equation, in which the canopy resistance rc is modelled, and \u201cindirect\u201d methods, based on the calculation of ET for a well-watered reference grass (ET0) with constant rc multiplied by a crop coefficient that represents the relative rate of ET from a specific crop and condition to that of the reference. This last procedure, standardized by FAO-56 bulletin, is the most widely adopted for the estimation of ET. However, in literature there are evidences that direct methods (P-M models with rc modelled) are still the most performing. In fact, for indirect methods, errors introduced by the calculation of ET0 considering a constant rc for reference crop and by the estimation of the crop coefficient, which actually integrates several physical and biological factors, can be relevant. This study evaluates the performance of different models for the estimation of ET for a maize agro-ecosystem in the Padana Plain (Northern Italy). The following models have been considered: 1) the \u201cone-step\u201d P-M model using a constant daily canopy resistance following the classical Monteith approach; 2) the \u201cone-step\u201d P-M model using a variable canopy resistance based on the approach of Katerji-Perrier, in which rc is calculated as a function of climate variables, aerodynamic resistance, vegetation type and its water status; 3) the \u201ctwo-step\u201d Shuttleworth model as updated by Shuttleworth and Gurney (1990), which combines one-dimensional models of crop transpiration and of soil evaporation, where canopy and soil surface resistances regulate the heat and mass transfer at the plant and soil surfaces, and aerodynamic resistances regulate those between these surfaces and the atmospheric boundary layer; 5) the indirect \u201csingle crop coefficient\u201d method proposed by FAO-56; 6) the indirect \u201cdouble crop coefficient\u201d method proposed by FAO-56, which allows the separation of soil evaporation and crop transpiration. Latent heat fluxes measured in 2006, 2010 and 2011 in an experimental maize field by eddy-covariance are used to evaluate the models accuracy. Crop, soil and meteo data monitored contextually are used for different models implementation. Data from the closest standard agro-meteorological station are adopted in the ET0 calculation for indirect methods. Results of this work confirm what reported by other authors in the literature, demonstrating that the calculation of crop evapotranspiration by direct method is more accurate than the use of indirect methods for both irrigated (2006, 2010) and rainfed (2011) conditions

Influence of Doping and Nanostructuration on n-Type Bi2(Te0.8Se0.2)3 Alloys Synthesized by Arc Melting

In competitive thermoelectric devices for energy conversion and generation, high-efficiency materials of both n-type and p-type are required. For this, Bi2Te3-based alloys have the best thermoelectric properties in room temperature applications. Partial replacement of tellurium by selenium is expected to introduce new donor states in the band gap, which would alter electrical conductivity and thermopower. We report on the preparation of n-type Bi2(Te1-xSex)3 solid solutions by a straightforward arc-melting technique, yielding nanostructured polycrystalline pellets. X-ray and neutron powder diffraction was used to assess Se inclusion, also indicating that the interactions between quintuple layers constituting this material are weakened upon Se doping, while the covalency of intralayer bonds is augmented. Moreover, scanning electron microscopy shows large surfaces perpendicular to the c crystallographic axis assembled as stacked sheets. Grain boundaries related to this 2D nanostructuration affect the thermal conductivity reducing it below 0.8 Wm−1K−1 at room temperature. Furthermore, Se doping increases the absolute Seebeck coefficient up to −140 μV K−1 at 400 K, which is also beneficial for improved thermoelectric efficiency.This research was funded by the Spanish Ministry of Economy and Competitivity for granting the project MAT2013-41099-R.Peer reviewe

Simulation of maize irrigation requirements at the regional scale : comparison between results obtained with measured and FAO-56 crop coefficient

The FAO-56 \u201csingle crop coefficient\u201d or \u201cdouble crop coefficient\u201d approaches are the most recommended and widely adopted procedures for the estimation of crop irrigation requirements. In these methods crop evapotranspiration in well-watered conditions is calculated by multiplying the grass reference evapotranspiration ET0 determined by the Penman-Monteith FAO-56 equation and a crop coefficient Kc depending on the crop type and its growing stage. In particular, the \u201cdouble crop coefficient\u201d allows the separation of soil evaporation and crop transpiration, splitting Kc in two different terms: a basal crop coefficient Kcb and a soil evaporation coefficient Ke. Many authors in the last fifteen years showed that the FAO Kc and Kcb tabulated coefficients, even if adjusted using the specific procedure based on local meteorological, irrigation and crop data suggested by FAO-56, tend to underestimate the observed crop coefficients in arid and semi-arid environments, while an overestimation often occurs for humid and semi-humid regions. In the literature differences up to \ub140% especially during the middle growth cycle are reported, mainly due to the complexity of the crop coefficient which actually integrates several physical and biological factors. The purpose of our research was to measure the Kc pattern for maize grown in the Lombardy Region (Northern Italy) and to evaluate the difference in crop irrigation requirements at a regional scale considering the measured Kc instead of the FAO tabulated values using a spatially distributed hydrological model. Kc was calculated for two experimental maize fields for years 2006, 2010 and 2011 as the ratio between actual crop evapotranspiration (ET) in well watered conditions and ET0. ET was measured using eddy-covariance technique while ET0 was determined from agro-meteorological data registered by the two standard meteo stations closest to the experimental areas. The second step of the research was achieved by using the distributed model IDRAGRA, which allows the computation of crop irrigation requirements on the basis of the \u201cdouble crop coefficient\u201d FAO-56 approach. This model has been adopted in various projects carried out in collaboration with the Lombardia Regional Authority. In the simulations, the spatial variability of soil types and the spatial and temporal variability of meteorological inputs was taken into account. Observed Kc and Kcb patterns showed that the mid-season stage tabulated values overestimate the observed values by around 18%; if adjustments with local data are considered for FAO crop coefficients, the average overestimation reduces to 14%. Results of the spatially distributed model application illustrated the effect of this overestimation on the crop irrigation requirements over the regional territory. Considerations on its repercussion in term of water resources planning were finally made

Sustainable water use for rice agro-ecosystems in northern Italy

I n the Mediterranean basin, rice is cultivated over an area of 1,300,000 hectares. The most important rice-producing countries are Italy and Spain in Europe (72% of the EU production; 345,000 ha), and Egypt and Turkey among the extra-EU countries (almost totality of the production; 789,000 ha). Traditionally, rice is grown under continuous flooding; thus, it requires much more irrigation than non-ponded crops. The MEDWATERICE project (PRIMA-Section 2-2018; https://www.medwaterice.org/) aims at exploring sustainability of innovative rice irrigation management solutions, in order to reduce rice water consumption and environmental impacts, and to extend rice cultivation outside of traditional paddy areas to meet the escalating demand. Within the MEDWATERICE project, irrigation management options to address the main site-specific problems are being tested for each rice areas involved in the project (IT, ES, PT, EG, TR). Case studies are being conducted in pilot farms, with the involvement of Stake-Holder Panels (SHPs) in each country. Data collected at the farm level will be extrapolated to the irrigation district level, to support water management decisions and policies. Moreover, indicators for quantitative assessment of environmental, economic and social sustainability of the irrigation options will be defined. This work illustrates the first year of results for the Italian Case Study (Lomellina area, Pavia) at the pilot farm scale. This area is characterized by a growing water scarcity in drought years in many districts. Within the farm managed by the National Rice Research Center (CRR), in the agricultural season 2019 the experimentation was conducted in six plots of about 20 m x 80 m each, with two replicates for each of the following water regimes: i) water-seeded rice with continuous flooding (WFL), ii) dry-seeded rice with continuous flooding from the 3-4 leaf stage (DFL), and iii) water seeded-rice with alternate wetting and drying from fertilization at the tillering stage (AWD). One out of the two replicates of each treatment was instrumented with: water inflow and outflow meters, set of piezometers, set of tensiometers and water tubes for the irrigation management in the AWD plots. A soil survey was conducted before the agricultural season (EMI sensor and physico-chemical analysis of soil samples). Periodic measurements of crop biometric parameters (LAI, crop height, crop rooting depth) were performed. Moreover, nutrients (TN, NO3, PO4, K) and two widely used pesticides (Sirtaki \u2013 a.i. Clomazone; Tripion E \u2013 a.i. MCPA) were measured in irrigation water (inflow and outflow), groundwater, and porous cups installed at two soil depths (20 and 70 cm, above and below the plough pan). Finally, rice grain yields and quality (As and Cd in the grain) were determined. First results in terms of cumulative water balance components (rainfall, irrigation inflow and outflow, difference in soil and ponding water storage, evapotranspiration, net percolation), water application efficiency (evapotranspiration over net water input), and water productivity (grain production over net water input), will be presented and discussed. Results of a 1D Richard-equation-based numerical simulation model applied to generalize results obtained under the different irrigation regimes will be moreover illustrated