NDF of the far zone field radiated by square sources

We consider the evaluation of the Number of Degrees of Freedom (NDF) of the field radiated by square sources in the far zone. The analysis is performed by employing a Singular-Value Decomposition (SVD) of the radiation operator in the two-dimensional scalar case. To this end, we start the analysis from simple geometries like two parallel strips and angle strips where analytical results can be established. For sufficiently spaced strip sources, the NDF depends only on their total electrical length. Then results for square sources follow on the same line. Finally, the numerical investigation of the case of concentric square sources, leading to an NDF independent on the inner source, opens the way to the discussion of the NDF of a full square source. In this case, it results that it depends only on the source perimeter. <br>

NDF of the far zone field radiated by square sources

We consider the evaluation of the Number of Degrees of Freedom (NDF) of the field radiated by square sources in the far zone. The analysis is performed by employing a Singular-Value Decomposition (SVD) of the radiation operator in the two-dimensional scalar case. To this end, we start the analysis from simple geometries like two parallel strips and angle strips where analytical results can be established. For sufficiently spaced strip sources, the NDF depends only on their total electrical length. Then results for square sources follow on the same line. Finally, the numerical investigation of the case of concentric square sources, leading to an NDF independent on the inner source, opens the way to the discussion of the NDF of a full square source. In this case, it results that it depends only on the source perimeter. <br>

Use of an Artificial Neural Network to Assess the Degree of Training of an Operator of Selected Devices Used in Precision Agriculture

The article concerns the issue of automatic recognition of the moment of achieving the desired degree of training of an operator of devices used in precision agriculture. The aim of the research was to build a neural model that recognizes when an operator has acquired the skill of operating modern navigation on parallel strips used in precision agriculture. To conduct the test, a standard device to assist the operator in guiding the machine along given paths, eliminating overlaps, was selected. The thesis was proven that the moment of operator training (meaning driving along designated paths with an accuracy of up to eight centimeters) can be automatically recognized by a properly selected artificial neural network. This network was learned on the basis of data collected during the observation of the operator training process, using a criterion defined by experts. The data collected in the form of photos of the actual and designated route was converted into numerical data and entered into the network input. The output shows the binary evaluation of the trip. It has been shown that the developed neural model will allow the determining of the moment when operators acquire the skills to drive a vehicle along the indicated path and thus shorten the training time.

Re-adjustments for MOM calculations of microstrip and stripline power dissipation

Microstrip and stripline losses in Method of Moments (MOM) calculations have an error arising from the large current density at the strip edges, characterized by an integration limit (W/2-d) in the equation for current density in thin strips (width W), where d is a fitting parameter. It depends primarily on the width of the MOM subsection on the edge of the strip. By comparing with the integration limit (W/2-Δ) for an actual strip with finite thickness, a correction factor is estimated. The equations incorporating d are confirmed by comparing with MOM calculations of isolated stripline, uniformly spaced parallel strips, striplines and microstrips close to ground planes, and with a strip in a uniform, externally applied magnetic field. The results are also consistent with measurements with copper. This makes the accuracy of the loss estimates commensurate with the excellence of the other aspects of MOM simulations.

Diffraction in grating optical filters with angular-selective light transmission

The effect of diffraction on the directional light transmittance of grating optical filters designed for smart windows is studied. The filter has an angular selective light transmission due to two thin-film gratings formed by "non-transmissive" (absorptive, reflective or scattering) parallel strips on the surfaces of a single or double glazed window. Methods are considered for calculating the op-timal slope angle of two filter’s gratings, their relative position on the opposite window surfaces and the widths of the strips of both gratings to minimize light transmission on a specific date and time of day for a given latitude and longitude of the building and azimuth of the window. A meth-od has been developed for calculating the diffraction at the input and output gratings of the filter with regard for a complex movement of the Sun relative to the window and a corresponding change in the incidence angle of the solar beams on the gratings. To evaluate a decrease in the light transmittance of the filter due to diffraction, an additional factor is introduced into the calcu-lation equation. Geometric parameters of the filters and diffraction are calculated. The values of the diffraction factor are 0.9999992 and 0.9999998 for single or double glazed windows, respec-tively, i.e., the influence of diffraction on the light transmittance of the grating filter can be ne-glected.

Предпосевная обработка семян озимой пшеницы поверхностным разрядом

The experimental results of the surface barrier discharge plasma products effect on soft winter wheat seeds in electrode configurations consisted of the parallel strips at a distance of 5 and 10 mm from each other are shown. In each electrode system, the seed treatment was carried out for 10, 60, 120 and 180 s at the sinusoidal voltages of 1.8, 2.1, 2.4 or 2.7 kV with the frequency of 4.4 kHz applied to the electrodes. The seeds were placed in one layer on the grounded plane at the distance of 10 mm from the dielectric barrier surface. The treatment effect was estimated by the morphological characteristics of 3-day seedlings. To control the airflow in the gap, the particle imaging visualization method was used. It is shown that treatment modes are divided into two principal groups. The first group represents the modes when the airflow reaches the plane on which the seeds are located, the second group represents the modes when the airflow does not reach this plane. In the first case (the distance between the strips is 10 mm, the voltage is 2.4−2.7 kV at all exposures), it is possible to achieve modes that stimulate germination. Seed germinating ability did not change and maintained high values at all considered modes.

A Smart Window for Angular Selective Filtering of Direct Solar Radiation

Thin-film grating coatings are proposed for smart windows to angular selective filtering of solar radiation. The gratings are formed by absorptive, reflective, or scattering parallel strips (made of chromogenic or other materials) alternating with directionally transmissive strips (untreated surface of pure glass) on two surfaces of the window pane(s). The smart window with grating optical filter has angular selective light transmission and partially or completely blocks the direct solar radiation in a preset angular range and transmits the scattered and reflected radiation without using the daylight redistribution devices. The results of numerical simulation and experimental confirmation of optimum slope angle of the strips on the pane(s), their widths, and relative position on two surfaces to minimize the directional light transmission of the window at the preset date and time of day taking into account orientation of the window to the cardinal, the latitude of the building, and the seasonal and daily distribution of the solar radiation intensity are demonstrated.