Grozdan Petrovic

Thermal images generated by a line-scanning technique: statistical properties

The analysis of statistical parameters of computer-generated therfial images by a line-scanning technique indicates an approach to efficient image transmission.

Thermal-image generation by line-scanning technique: a new computer model

A new computer model for the generation of thermal images of a flat terrain by the line-scanning technique from a moving platform is presented. The model is based on a bottom-up simulation process and the pixel-by-pixel generation of infrared thermal images. The terrain is modeled by a periodic repetition of an arbitrary two-dimensional temperature distribution over a flat area. The double discrete Fourier series of the terrain temperature, including correlation length and the transfer function of the scanning optics, is used. Several computer-generated thermal images are produced to illustrate the model. The geometrical deformations, the space filtration, and the gray-level variation with the scanning angle on generated images are in agreement with theoretical predictions.

Packet Error Probability in a Three-Branch Diversity System with Majority Combining

In this paper, we derive a closed-form expression for the packet error probability in a three-branch diversity transmission scheme with distinct bit error probabilities in each branch and a majority combining technique implemented on a data link layer. Based on the derived expression and its approximate form, we also demonstrate that the proposed technique reduces the packet error probability by a factor numerically equal to one third of the packet size, compared to the conventional selection combining.

Implementation and performance analysis of active queue management mechanisms

In this paper, we describe active queue management (AQM) mechanisms that are employed in the Internet protocol (IP) routers. We address the functionality and implementation of AQM blocks in IP routers. We also describe the benefits of the AQM mechanisms and justify the need for their implementation. Simulation results illustrate the fairness and the efficient use of resources in networks with the AQM support.

Statistical analysis of thermal images generated by line scanning

In this paper a statistical analysis of thermal images, obtained by the line scanning technique, with the view of reducing the image data redundancy is given. The analyzed thermal images are produced by the infrared line scanner on board and by a computer simulation. The statistical analysis is based on grey level mean values, standard deviations and correlations. A special filtering method is proposed to eliminate the line-like interference which appears on enlarged thermal image photographs made from the film.

Packet Error Probability in Multi-Path Diversity Scheme with Majority Combining

In this paper, we derive the exact expression for the packet error probability in the case of m-path diversity scheme with packet combining using majority decision technique. The individual paths are modeled as independent and slow-varying binary symmetric channels with distinct values for bit error probabilities. We introduce an equivalent channel probability and spreading coefficients to analyze the derived expression. MATLAB code for numerical evaluations and an illustrative example for cases m = 3, 5, 7, 9, and 11 were also presented.

Throughput efficiency of the GBN ARQ scheme with xor packet combining

In this paper, we derived an analytical expression for the throughput efficiency in a GBN ARQ telecommunication scheme with the xor packet combining. The analysis was based on retransmission cycles. Results show that including the xor packet combining leads to better performance compared to the ordinary single copy GBN ARQ scheme.

Computer-generated thermal test images and the analysis of line-scanning effects

Deterministic images in the shapes of cos-like variation of average terrain temperature are computer generated with superimposed noise fluctuations due to the terrain and SPRITE detector. The thermal infrared images in this model are generated pixel by pixel. The images are made for periodic cos-like structures along the x-axis, y-axis and isolated hot plates on the flat terrain. The effects of line scanning on noiseless and noisy images are analyzed.