arXiv subjects

Shahram Amiri

Publications and source records attributed to Shahram Amiri.

4 recordsLinked to original sources

arXiv2026

Predicting Fruit Quality with a Hybrid Machine Learning and Image Processing Approach

Fruit spoilage is a significant issue in agriculture, leading to substantial economic losses. Addressing this, our study introduces a hybrid approach combining image processing and deep learning to assess fruit freshness. We developed an image processing algorithm that quantifies spoilage on a scale from 0 (fully fresh) to 100 (fully rotten). Alongside, we trained a convolutional neural network (CNN) to perform binary classification (fresh or rotten) using a large dataset of fruit images. The outcomes of both methods were synthesized using logistic regression to enhance the accuracy of freshness predictions. Subsequently, this logistic regression model was utilized to enable the image processing algorithm to provide binary classification based on its percentage output, thus eliminating the need for the CNN in real-time applications. Our approach, which does not require high computational resources, achieved real-time performance and was validated with over 90% accuracy on a dataset comprising apples and oranges. The primary limitation lies in the requirement for fruits to be isolated on a background that must be either white or transparent, suggesting future improvements could include advanced segmentation models to automate background removal. This study's results highlight the potential of integrating simple image processing techniques with machine learning to provide practical solutions in the agricultural sector.

cs.CV↗

arXiv2012

RRI-GBT Multi-Band Receiver: Motivation, Design & Development

We report the design and development of a self-contained multi-band receiver (MBR) system, intended for use with a single large aperture to facilitate sensitive & high time-resolution observations simultaneously in 10 discrete frequency bands sampling a wide spectral span (100-1500 MHz) in a nearly log-periodic fashion. The development of this system was primarily motivated by need for tomographic studies of pulsar polar emission regions. Although the system design is optimized for the primary goal, it is also suited for several other interesting astronomical investigations. The system consists of a dual-polarization multi-band feed (with discrete responses corresponding to the 10 bands pre-selected as relatively RFI-free), a common wide-band RF front-end, and independent back-end receiver chains for the 10 individual sub-bands. The raw voltage time-sequences corresponding to 16 MHz bandwidth each for the two linear polarization channels and the 10 bands, are recorded at the Nyquist rate simultaneously. We present the preliminary results from the tests and pulsar observations carried out with the Green Bank Telescope using this receiver. The system performance implied by these results, and possible improvements are also briefly discussed.

astro-ph.IM↗

arXiv2012

Multi-Band Feeds: A Design Study

Broadband antenna feeds are of particular interest to existing and future radio telescopes for multi-frequency studies of astronomical sources. Although a 1:15 range in frequency is difficult to achieve, the well-known Eleven feed design offers a relatively uniform response over such a range, and reasonably well-matched responses in E & H planes. However, given the severe Radio Frequency Interference in several bands over such wide spectral range, one desires to selectively reject the corresponding bands. With this view, we have explored the possibilities of having a multi-band feed antenna spanning a wide frequency range, but which would have good response only in a number of pre-selected (relatively) RFI-free windows (for a particular telescope-site). The designs we have investigated use the basic configuration of pairs of dipoles as in the Eleven feed, but use simple wire dipoles instead of folded dipoles used in the latter. From our study of the two designs we have investigated, we find that the design with feed-lines constructed using co-axial lines shows good rejection in the unwanted parts of the spectrum and control over the locations of resonant bands.

astro-ph.IM↗

arXiv2009

A 50 MHz System for GMRT

This paper describes a 50 MHz system being developed for GMRT to provide imaging capability in the frequency range 30-90MHz. Due to its larger collecting area and higher antenna efficiency, the low frequency GMRT system will be several times more sensitive than the present 74 MHz VLA system and is likely to remain a competitive instrument in this frequency band. In the first phase of this project, receiver systems consisting of V-dipole feeds and front-ends have been installed on four of the thirty GMRT antennas. Test observations were carried out on a number of bright 3C sources. The initial results are encouraging. This paper will also describe results of simultaneous observations carried out using the existing GMRT correlator, the new GMRT software correlator and a system employing digitization and direct recording of signals at two antenna bases.

astro-ph.IM↗