Strip Source Research Articles

Influence of Tillage Practices and Nitrogen Sources on Nitrogen Availability and Uptake of Rice

Aim: Evaluation of tillage practices and nitrogen sources on nitrogen availability in soil and nitrogen uptake of rice
 Study design: The experiment was laid out in strip-plot design with different tillage practices in horizontal strip and different nitrogen sources in vertical strip and was replicated thrice.
 Place and duration of study: The field experiment was conducted during the kharif season of 2019 and 2020 at the Agricultural College Farm, Bapatla, ANGRAU, Lam, Guntur, Andhra Pradesh.
 Methodology: The experiment was performed with twenty treatments in strip-plot design. The horizontal strip comprised four different tillage practices and vertical strip with five different nitrogen sources. Rice variety “BPT-5204” was taken as the test variety. Observations of the crop and soil during the experimentation were recorded at regular intervals. The significance of the treatment impact was examined by the test.
 Results: Among tillage practices, higher nitrogen uptake by rice grain (85.30 and 86.96 Kg ha-1) and straw (41.21 and 41.91 Kg ha-1) during 2019-20 and 2020-21, respectively was recorded in conventional tillage (T4) which was found statistically on a par with dry seeding on puddled soil (T1) (81.15 and 82.79 Kg ha-1, 38.59 and 39.20 Kg ha-1 during 2019-20 and 2020-21, respectively) and significantly superior over reduced tillage (T2) and minimum tillage (T3). Among nitrogen source, application of 50% STBN through fertilizer + 50% N through cured poultry manure (N5) registered the highest uptake of nitrogen in grain and straw (85.38 and 87.02 Kg ha-1. 42.09 and 42.76 Kg ha-1 during 2019-20 and 2020-21, respectively) and it was found significantly on a par with 75% STBN through fertilizer + 25% N through cured poultry manure (N4) and significantly superior over 50% STBN through fertilizer + 50% N through FYM (N3), 75% STBN through fertilizer + 25% N through FYM (N2), and 100% STBN through fertilizer (N1) treatment.

On the Sampling of the Fresnel Field Intensity over a Full Angular Sector

In this article, the question of how to sample the square amplitude of the radiated field in the framework of phaseless antenna diagnostics is addressed. In particular, the goal of the article is to find a discretization scheme that exploits a non-redundant number of samples and returns a discrete model whose mathematical properties are similar to those of the continuous one. To this end, at first, the lifting technique is used to obtain a linear representation of the square amplitude of the radiated field. Later, a discretization scheme based on the Shannon sampling theorem is exploited to discretize the continuous model. More in detail, the kernel of the related eigenvalue problem is first recast as the Fourier transform of a window function, and after, it is evaluated. Finally, the sampling theory approach is applied to obtain a discrete model whose singular values approximate all the relevant singular values of the continuous linear model. The study refers to a strip source whose square magnitude of the radiated field is observed in the Fresnel zone over a 2D observation domain.

PSF Analysis of the Inverse Source and Scattering Problems for Strip Geometries

This paper is concerned with estimating the achievable resolution in the reconstruction of strip sources from the knowledge of its radiated field and strip objects from the knowledge of its scattered field. In particular, the study focuses on the evaluation of the point spread function (PSF), providing the reconstruction of a point-like unknown. Since this can be performed only numerically for most geometries, an approximate closed-form evaluation is introduced and compared with the exact one. Numerical results confirm the approximation accuracy, at least in the main lobe region of the PSF, which is the most important, as far as the discussion about resolution is concerned. The main results of the analysis concern the space invariance of the PSF of the considered geometries, which means that resolution is the same over the whole investigation domain, and the appreciation of its values for the inverse source and scattering problems.

Ensuring accuracy in the electromechanical processing of parts holes with a high-temperature strip source

Тhe accuracy of the holes in the electro - mechanical processing with a high-temperature strip tool is achieved by the development of original tooling. The article presents technical solutions of tool and technological equipment to ensure the accuracy of holes in the implementation of processes of electromechanical processing with a high-temperature strip source. The results of measurements on cylindricality of the hole of the sleeve bearing of the upper head of the connecting rod of the Yaroslavl Engine Plant engine after volumetric electromechanical mandrel are presented, confirming the effectiveness of using the developed tooling.

Resolution limits in inverse source problem for strip currents not in Fresnel zone.

This paper deals with the classical question of estimating achievable resolution in terms of configuration parameters in inverse source problems. In particular, the study is developed for two-dimensional prototype geometry, where a strip source (magnetic or electric) is to be reconstructed from its radiated field observed over a bounded rectilinear domain parallel to the source. Resolution formulas are well known when the field is collected in the far field or in the Fresnel zone of the source. Here, the plan is to expand those results by removing the geometrical limitations due to the far field or Fresnel approximations. To this end, the involved radiation operators are recast as Fourier-type integral operators upon introducing suitable variable transformations. For magnetic sources, this allows one to find a closed-form approximation of the singular system and hence to estimate achievable resolution, the latter given as the main beam width of the point-spread function. Unfortunately, this does not happen for electric currents. In this case, the radiation operator is inverted by a weighted adjoint inversion method (a back-propagation-like method) that directly allows one to find an analytical expression of the point-spread function and hence of the resolution. The derived resolution formulas are the same for magnetic and electric currents; they clearly point out the role of geometrical parameters and coincide with the one pertaining to the Fresnel zone when the geometry verifies the Fresnel approximation. A few numerical examples are also enclosed to check the theory.

Temperature field due to a moving heat source in machining orthotropic composites with arbitrary fiber orientation

Milling of fiber reinforced plastics (FRP) is challenging with respect to surface integrity and tool wear due to high process temperatures. The maximum temperatures occurring in the workpiece determine the extent of the matrix decomposition area. Improving the workpiece quality therefore requires an understanding of its internal temperature distribution during milling. However, steep temperature gradients and high mechanical stress make measurements of temperature fields in the cutting zone difficult. In addition, thermal properties change depending on the fiber orientation in the case of orthotropic FRP.In this paper, an existing model describing the temperature field for isotropic materials is extended to unidirectional, orthotropic FRP. Here, the thermal impact of an end mill upon the machined surface is represented by a strip-shaped heat source which moves with the feed velocity along a semi-infinite space. Starting with the temperature field of an instantaneous point source, multiple integration steps and a coordinate transformation lead to the temperature field of the moving strip source for orthotropic materials with arbitrary fiber orientation.Using this analytical approach, two-dimensional temperature fields within the workpiece can be calculated for various feed velocities, heat source widths and fiber orientation angles. A cross verification of the analytical solution is successfully carried out by comparing it to a numerical simulation. Furthermore, temperature measurements during end milling of carbon fiber reinforced plastics using thermocouples confirm these results for different fiber orientations.The derived model can be applied to a variety of heat flow problems relevant for orthotropic materials, e.g. other machining technologies.

Application of a Strip Source of Heat for Measuring Thermal Conductnity of Semi-Infinite Solids

Para solicitação de resumo, entrar em contato com editor-chefe (editor@sbgf.org.br).

Measurement Sensitivity Analysis of the Transient Hot Source Technique Applied to Flat and Cylindrical Samples

The transient source measurement technique is a nonintrusive, nondestructive method of measuring the thermal properties of a given sample. The transient source technique has been implemented using a wide variety of sensor shapes or configurations. The modern transient plane source (TPS) sensor is a spiral-shaped sensor element which evolved from transient line and transient hot strip (THS) source techniques. Commercially available sensors employ a flat interface that works well when test samples have a smooth, flat surface. The present work provides the basis for a new, cylindrical strip (CS) sensor configuration to be applied to cylindrical surfaces. Specifically, this work uses parameter estimation theory to compare the performance of CS sensor configurations with a variety of existing flat sensor geometries, including TPS and THS. A single-parameter model for identifying thermal conductivity and a two-parameter model for identifying both thermal conductivity as well as volumetric heat capacity are considered. Results indicate that thermal property measurements may be carried out with greater measurement sensitivity using the CS sensor configuration than similar configurations for flat geometries. In addition, this paper shows how the CS sensor may be modified to adjust the characteristic time scale of the experiment, if needed.

On the singular spectrum of radiation operators in the non-reactive zone: the case of strip sources

In this work, the singular spectrum of radiation operators is studied for both magnetic and electric sources. The aim is to establish a theory that allow one to foresee the information content of the data as a function of the parameters of the radiation configuration. This is a classical problem and some results have been presented, mainly referring to the far-zone and the Fresnel paraxial zone. Here, we extend the previous studies by considering radiation configurations where no constraints on the source and observation domains are imposed as needed by the far-zone or the Fresnel paraxial zone approximation. However, it is assumed that evanescent waves are negligible. To keep the analysis simple, the case of strip currents is considered within a two-dimensional scalar geometry.

Inverse source in the presence of a reflecting plane for the strip case.

In this paper the inverse source problem in the presence of a reflecting plane is dealt with for a two-dimensional configuration and bounded rectilinear strip sources. The cases of both orthogonal and parallel (to the reflecting plane) sources are considered. Analytical arguments are developed to estimate the singular value decomposition of the pertinent radiation operator. This allows highlighting of the role played by the reflecting plane in the so-called number of degrees of freedom of the radiated field as well as in the achievable resolution while reconstructing the unknown sources.

Note: Simulation and test of a strip source electron gun.

We present simulation and test of an indirectly heated strip source electron beam gun assembly using Stanford Linear Accelerator Center (SLAC) electron beam trajectory program. The beam is now sharply focused with 3.04 mm diameter in the post anode region at 15.9 mm. The measured emission current and emission density were 1.12 A and 1.15 A/cm(2), respectively, that corresponds to power density of 11.5 kW/cm(2), at 10 kV acceleration potential. The simulated results were compared with then and now experiments and found in agreement. The gun is without any biasing, electrostatic and magnetic fields; hence simple and inexpensive. Moreover, it is now more powerful and is useful for accelerators technology due to high emission and low emittance parameters.

Focusing of long waves with finite crest over constant depth

Tsunamis are long waves that evolve substantially, through spatial and temporal spreading from their source region. Here, we introduce a new analytical solution to study the propagation of a finite strip source over constant depth using linear shallow-water wave theory. This solution is not only exact, but also general and allows the use of realistic initial waveforms such asN-waves. We show the existence of focusing points forN-wave-type initial displacements, i.e. points where unexpectedly large wave heights may be observed. We explain the effect of focusing from a strip source analytically, and explore it numerically. We observe focusing points using linear non-dispersive and linear dispersive theories, analytically; and nonlinear non-dispersive and weakly nonlinear weakly dispersive theories, numerically. We discuss geophysical implications of our solutions using the 17 July 1998 Papua New Guinea and the 17 July 2006 Java tsunamis as examples. Our results may also help to explain high run-up values observed during the 11 March 2011 Japan tsunami, which are otherwise not consistent with existing scaling relationships. We conclude thatN-waves generated by tectonic displacements feature focusing points, which may significantly amplify run-up beyond what is often assumed from widely used scaling relationships.

A simple alternative approach to assess the effect of the above-water bow form on the ship added resistance

In the paper, a simple alternative approach to assess the effect of the above-water bow form on the added resistance for the ship advancing in longitudinal waves is investigated. The strip theory and source distribution method are applied to solve the corresponding boundary conditions and analyze nonlinear motions and mean added resistance. In order to calculate the instantaneous ship motions and nonlinear forces with respect to the different draft, the time domain simulation technique based on the 4th Runge–Kutta method is applied here, and the instantaneous mean added resistance for a ship with different bow flare can be further obtained. The “total quasi-mean added resistance” is then defined to assess the virtual effect of the above-water bow flare shape. The present results show that the larger the bow flare, the larger the added resistance. The effect of wave profile along the ship length on the added resistance is also deeply investigated for discussions in the study.

Simulation of soil water dynamics under subsurface drip irrigation from line sources

A mathematical model which describes water flow under subsurface drip lines taking into account root water uptake, evaporation of soil water from the soil surface and hysteresis in the soil water characteristic curve θ( H) is presented. The model performance in simulating soil water dynamics was evaluated by comparing the predicted soil water content values with both those of Hydrus 2D model and those of an analytical solution for a buried single strip source. Soil water distribution patterns for three soils (loamy sand, silt, silty clay loam) and two discharge rates (2 and 4 l m −1 h −1) at four different times are presented. The numerical results showed that the soil wetting pattern mainly depends on soil hydraulic properties; that at a time equal to irrigation duration decreasing the discharge rate of the line sources but maintaining the applied irrigation depth, the vertical and horizontal components of the wetting front were increased; that at a time equal to the total simulation time the discharge rate has no effect on the actual transpiration and actual soil evaporation and a small effect on deep percolation. Also the numerical results showed that when the soil evaporation is neglected the soil water is more easily taken up by the plant roots.

Transformation of energy and composition of gas mixtures in a collision of rarefied supersonic flows

Transformation of energy and composition of gas mixtures in a convergent flow from a strip source on a cylindrical surface toward the axis is systematically studied with the use of the direct simulation Monte Carlo method. Information on the influence of gas-flow rarefaction and system geometry on the temperature and concentration of the heavy gas in a dense cloud formed on the axis is obtained. The use of convergent supersonic flows is demonstrated to offer new possibilities for research in the field of physical gas dynamics.

Quasilinear infiltration from an elliptical cavity

We develop analytic solutions to the linearized steady-state Richards equation for head and total flowrate due to an elliptic cylinder cavity with a specified pressure head boundary condition. They are generalizations of the circular cylinder cavity solutions of Philip [Philip JR. Steady infiltration from circular cylindrical cavities. Soil Sci Soc Am J 1984;48:270–8]. The circular and strip sources are limiting cases of the elliptical cylinder solution, derived for both horizontally- and vertically-aligned ellipses. We give approximate rational polynomial expressions for total flowrate from an elliptical cylinder over a range of sizes and shapes. The exact elliptical solution is in terms of Mathieu functions, which themselves are generalizations of and computed from trigonometric and Bessel functions. The required Mathieu functions are computed from a matrix eigenvector problem, a modern approach that is straightforward to implement using available linear algebra libraries. Although less efficient and potentially less accurate than the iterative continued fraction approach, the matrix approach is simpler to understand and implement and is valid over a wider parameter range.

Explicit Infiltration Function for Furrows

This study addresses infiltration from furrows or narrow channels. The basic approach is to develop the two-dimensional infiltration as a combination of the corresponding one-dimensional vertical and an edge effect. The idea is borrowed from previous applications for infiltration from disc and strip sources. The assumption is tested directly with numerical experiments using four representative soils and three furrow shapes (triangular, rectangular, and parabolic). The edge effect is the difference between the cumulative infiltration per unit of adjusted wetting perimeter and the corresponding one-dimensional infiltration. A general conclusion is that the edge effect is linearly related to time. In addition, it was observed that the two empirical parameters in the function used to relate the edge effect with time have narrow ranges and are related to soil hydraulic parameters, furrow shape, the boundary and initial conditions and additional geometric factors. The approach leads to a physically based infilt...

Infiltration from a strip source

This study addresses infiltration from strip sources of water on the soil surface. The problem arises as the limiting case of furrow irrigation as well as for closely spaced surface drip emitters. Previously, the most common approach used for describing flow from strip sources was numerical modeling based on Richards' equation. This work investigates a third approach borrowed from previous applications for infiltration from disc sources. The assumption is that when the cumulative infiltration is expressed per unit area of the wetted strip, the difference of that value and one‐dimensional infiltration is linear with time. We test the assumption directly by doing numerical experiments with six representative soils and using various strip widths, boundary, and initial water contents. The general conclusions are that the differences between the cumulative infiltration per unit source area for a strip and a planar source are linearly related to time but that a single value of the proportionality factor γ is generally inadequate. Values of γ are found between 0.64 and 1.16. An effort was made to relate γ to soil hydraulic parameters and strip width as well as to the boundary and initial conditions. Once γ is defined, the strip infiltration follows immediately if the corresponding one‐dimensional solution is known without the necessity of performing a two‐dimensional simulation.

An 850-μm SCUBA map of the Groth Strip and reliable source extraction

We present an 850-micron map and list of candidate sources in a 70 arcmin^2 sub-area of the Groth Strip observed using SCUBA. We initially detect 7 candidate sources with signal-to-noise ratios (SNRs) between 3.0 and 3.5 and 4 candidate sources with SNR > 3.5. Simulations suggest that on average in a map this size one expects 1.6 false positive sources for SNR > 3.5 and 4.5 for 3 < SNR < 3.5. Flux boosting in maps is a well known effect and we have developed a simple Bayesian prescription for estimating the unboosted flux distribution and used this method to determine the best flux estimates of our sources. This method is easily adapted for any other modest signal-to-noise survey in which there is prior knowledge of the source counts. We performed follow-up photometry in an attempt to confirm or reject 5 of our source candidates. We confirm the reality of 2 of the SCUBA sources, although at lower levels than suggested in the map and we find that the photometry results are consistent with and confirm the de-boosted map fluxes. Our final candidate source list contains 3 sources, including the 2 confirmed detections and 1 further candidate source with SNR > 3.5 which has a reasonable chance of being real.

Semi-analytical solutions for solute transport in fractured porous media using a strip source of finite width

Transient and steady-state analytical solutions are derived to investigate solute transport in a fractured porous medium consisting of evenly spaced, parallel discrete fractures. The solutions incorporate a finite width strip source, longitudinal and transverse dispersion in the fractures, source decay, aqueous phase decay, one-dimensional diffusion into the matrix, sorption to fracture walls, and sorption within the matrix. The solutions are derived using Laplace and Fourier transforms, and inverted by interchanging the order of integration and utilizing a numerical Laplace inversion algorithm. The solutions are verified for simplified cases by comparison to solutions derived by Batu [Batu V. A generalized two-dimensional analytical solution for hydrodynamic dispersion in bounded media with the first-type condition at the source. Wat Resour Res 1989;25(6):1125] and Sudicky and Frind [Sudicky EA, Frind EO. Contaminant transport in fractured porous media: analytical solutions for a system of parallel fractures. Wat Resour Res 1982;18(6):1634]. The application of the solutions to a fractured sandstone demonstrates that narrower source widths and larger values of transverse dispersivity both lead to lower downstream concentrations in the fractures and shorter steady-state plumes. The incorporation of aqueous phase decay and source concentration decay both lead to lower concentrations and shorter plumes, with even moderate amounts of decay significantly shortening the persistence of contamination.