A SIFT Description Approach for Non-Uniform Illumination and Other Invariants

The new improvement keypoint description technique of image-based recognition for rotation, viewpoint and non-uniform illumination situations is presented. The technique is relatively simple based on two procedures, i.e., the keypoint detection and the keypoint description procedure. The keypoint detection procedure is based on the SIFT approach, Top-Hat filtering, morphological operations and average filtering approach. Where this keypoint detection procedure can segment the targets from uneven illumination particle images. While the keypoint description procedures are described and implemented using the Hu moment invariants. Where the central moments are being unchanged under image translations. The sensitivity, accuracy and precision rate of data sets were evaluated and compared. The data set are provided by color image database with variants uniform and non-uniform illumination, viewpoint and rotation changes. The evaluative results show that the approach is superior to the other SIFTs in terms of uniform illumination, non-uniform illumination and other situations. Additionally, the paper demonstrates the high sensitivity of 100%, high accuracy of 83.33% and high precision rate of 80.00%. Comparisons to other SIFT approaches are also included.

ON THE CAPACITY OF SOLAR CELLS UNDER PARTIAL SHADING CONDITIONS

A photovoltaic system under uniform illumination conditions has only one global maximum power point, but this same panel in the case of partial shading conditions can have more maxima on the power-voltage curve. The motivation of this work are two-fold: to show nonlinear capacitance of solar cell and to propose a determination technique for partial shading condition. The author shows the results of measurements on a photovoltaic system under different lighting conditions. Shows the effect of capacitance on the shape of the response to excitation in the form of a load. The paper also shows which photovoltaic cell parameters influence the shape of the C-V curve.

Создание равномерных покрытий импульсным лазерным осаждением

The present paper deals with the selection of laser beam processing parameters that guarantee the formation of thin coatings with even thickness by means of the laser beam deposition. Laser deposition was carried out in the atmosphere of Ar and Si and SiC samples were used as a source for the deposited material. Preliminary experiments show that there is a direct dependency between the brightness of the image of the deposited layer (at uniform illumination conditions) and its thickness. Therefore, it was possible to determine the thickness of the deposited layer for various processing parameters and to calculate the laws of motion of the work piece that guarantee the deposition of the layer with a minimal deviation of thickness from the required value. Calculated parameters were successfully used for the deposition of coatings on a substrate of a relatively large area.

Silicon Lens Optimization to Create Diffuse, Uniform Illumination from Incoherent THz Source Arrays

Arrays of terahertz (THz) sources provide a pathway to overcoming the radiation power limitations of single sources. Several independent sources of THz radiation may be implemented in a single integrated circuit, thereby realizing a monolithic THz source array of high output power. Integrated THz sources must generally be backside-coupled to extended hemispherical dielectric lenses in order to suppress substrate modes and extract THz power. However, this lens also increases antenna gain and thereby produces several non-overlapping beams. This is because individual source pixels are relatively large. Hence, their spatial separation on-chip translates to angular separation in the far-field. In other words, there are gaps in their field of view into which very little THz power is projected. Therefore, they cannot homogeneously illuminate an imaging target. This article presents a simple, practical, and scalable method to convert arrays of incoherent THz sources into a diffuse, uniform illumination source without the need for reducing pixel size. Briefly, individual beam divergence is optimized by tailoring the dimensions of the extended hemispherical dielectric lens such that the far-field beams of adjacent source pixels overlap and combine to form a uniform far-field beam. We applied this method to an incoherent 8 × 8-pixel THz source array radiating 10.3 dBm at 0.42 THz as a proof of concept and thereby realized a 10.3-dBm 0.42-THz diffuse, uniform illumination source that was then deployed in a demonstration of THz active imaging.