Stefan Panić

PERFORMANCE, ACCURACY, AND PREDICTIVE CHUNK OPTIMIZATION OF PARALLEL SIMPSON AND TRAPEZOIDAL INTEGRATION METHODS

Parallel numerical integration is a fundamental component of many scientific and engineering applications, yet its performance depends strongly on workload partitioning strategies. In shared-memory environments, the choice of chunk size directly affects load balancing, scheduling overhead, and cache utilization, particularly when adaptive numerical methods are employed. This paper presents an analysis of the performance, accuracy, and scalability of four numerical integration techniques: Simpson’s rule, Adaptive Simpson’s rule, the Trapezoidal rule, and the Adaptive Trapezoidal rule, implemented in a multi-threaded execution model. Execution-time distributions are analyzed across a wide range of chunk sizes and thread counts, revealing substantial performance variability and method-dependent optimal chunk configurations. In addition to performance evaluation, numerical accuracy is assessed to highlight trade-offs between computational efficiency and error reduction. Based on empirical observations, optimal chunk ranges are identified and used to construct a predictive model that estimates near-optimal chunk configurations as a function of the number of threads. The proposed approach enables efficient parameter selection without exhaustive tuning and demonstrates the feasibility of predictive chunk optimization for parallel numerical integration.

AN INFORMATION-PHYSICAL PERSPECTIVE ON FADING PROCESS TRANSITIONS BASED ON HIGHER ORDER STATISTICS

This paper proposes a novel theoretical framework for analyzing fading channels by introducing the concepts of energetic orbits and entropy barriers. Inspired by atomic physics and thermodynamic analogies, here the signal envelope is modeled as a stochastic process whose transitions between different structural regimes (extrema, inflection points, level crossings) correspond to energy quantization events. Each transition is associated with a local information-energy quantum, defined as a product of amplitude displacement and transition count, normalized by local entropy. Furthermore, the ideas of entropic spin and degeneracy of states have been explored, and the dispersion of level-crossing processes, extremum-crossing process, inflection point-crossing process, saddle point-crossing process (LCR, ECR, ICR, SCR) through an autocorrelation-based energetic formalism has been characterized. This approach enables the construction of a layered energetic map of fading dynamics and offers new insights into the structural behavior of wireless signals under stochastic fluctuations.

AN APPLICATION OF RESIDUE NUMBER SYSTEM ARITHMETICS TO SECURE HASH FUNCTIONS DESIGN

This paper presents a cryptographic hash function based on the Residue Number System (RNS), designed to enhance security and computational efficiency. The function leverages the parallelism and modular properties of RNS to achieve high-speed processing while maintaining strong diffusion and resistance to various cryptanalytic attacks. Experimental results confirm that the proposed function exhibits a pronounced Avalanche effect, ensuring that minor changes in the input result in significant alterations in the hash output. Additionally, statistical analysis using the ENT test demonstrates a high level of entropy and uniform distribution of hash values, reinforcing the function’s unpredictability—an essential characteristic for cryptographic security. The proposed hash function is suitable for applications in digital signatures, data integrity verification, and authentication systems, offering advantages in environments requiring high computational efficiency.

ON THE SECOND ORDER STATISTICS OF THE RATIO OF TWO FISHER-SNEDECOR RANDOM VARIABLES AND ITS APPLICATION TO INTERFERENCE LIMITED COMMUNICATIONS

The paper investigates the higher order statistics of the ratio of two Fisher-Snedecor F (FS-F) random variables (RVs) and its application to wireless communications in the presence of co-channel interference. Namely, the work provides novel expressions for probability density function (PDF), cumulative density function (CDF), level crossing rate (LCR) and average fade duration (AFD) of the ratio of two FS-F RVs. Numerical examples of the analytically derived statistical measures in terms of FS-F multi-path and shadowing parameters are shown and examined. Moreover, the impact of the number of interferes on the considered measures are further presented and examined.

COVID-19 RISK ASSESSMENT IN PUBLIC TRANSPORT USING AMBIENT SENSOR DATA AND WIRELESS COMMUNICATIONS

Covid-19 causes one of the most alarming global health and economic crises in modern times. Countries around the world establish different preventing measures to stop or control Covid-19 spread. The goal of this paper is to present methods for the evaluation of indoor air quality in public transport to assess the risk of contracting Covid-19. The first part of the paper involves investigating the relationship between Covid-19 and various factors affecting indoor air quality. The focus of this paper relies on exploring existing methods to estimate the number of occupants in public transport. It is known that increased occupancy rate increases the possibility of contamination as well as indoor carbon dioxide concentration. Wireless data collection schemes will be defined that can collect data from public transportation. Collected data are envisioned to be stored in the cloud for data analytics. We will present novel methods to analyze the collected data by considering the historical data and estimate the virus contagion risk level for each public transportation vehicle in service. The methodology is expected to be applicable for other airborne diseases as well. Real-time risk levels of public transportation vehicles will be available through a mobile application so that people can choose their mode of transportation accordingly.

DETERMINATION OF ACCELERATED FACTORS IN GRADIENT DESCENT ITERATIONS BASED ON TAYLOR’S SERIES

In this paper the efficiency of accelerated gradient descent methods regarding the way of determination of accelerated factor is considered. Due to the previous researches we assert that the use of Taylor’s series of posed gradient descent iteration in calculation of accelerated parameter gives better final results than some other choices. We give a comparative analysis of efficiency of several methods with different approaches in obtaining accelerated parameter. According to the achieved results of numerical experiments we make a conclusion about the one of the most optimal way in defining accelerated parameter in accelerated gradient descent schemes.

ANALISYS OF THE INFLUENCE OF COMMUNICATION PARAMETERS OF FSO CHANNELS ON THE RECEPTION QUALITY

In this paper, the signal transmission in the Free-Space Optics (FSO) communication system using the software package OptiSystem 7.0 is analyzed. The influence of parameters FSO (Free-Space-Optics) channels (Range, Attenuation, Beam Divergence, Transmitter Loss, Receiver Loss, and Additional Losses) on the reception quality is considered. The reception quality is analyzed according to the values of BER (Bit Error Ratio) and Q factor. Graphics and tables of the changes of BER and Q factor depending on the parameters of FSO are given. Also, the eye diagrams for the characteristic parameter values are given.

HK DISTRIBUTION MODEL FOR ATMOSPHERIC TURBULENCE CHANNEL UNDER THE INFLUENCE OF POINTING ERRORS

In this paper, HK statistical model is considered. The application of HK distribution in modeling atmospheric turbulence channel under the influence of strong and weak turbulences and all irradiance fluctuations are discussed. Expression for atmospherics turbulence channel model, pointing error models and path loss are given. Probability density functions (PDF) for both pointing error models (zero boresight and nonzero boresight) are calculated and graphically represented. Also, average bit-error-rate (BER) for zero boresight pointing error and nonzero boresight pointing error are calculated and graphically represented. Closed form expression for PDF and BER are given. Impact of zero boresight pointing error and nonzero boresight pointing error on transmission over atmospheric turbulence channel in FSO system is explained.

LEVEL CROSSING RATE OF MACRODIVERSITY WITH THREE MICRODIVERSITY SC RECEIVERS OVER GAMMA SHADOWED NAKAGAMI-M CHANNEL

Macrodiversity system with macrodiversity selection combining (SC) receiver and three microdiversity SC receivers operating over Gamma shadowed Nakagami-m multipath fading environment is considered in this work. Level crossing arte of signals at outputs microdiversity SC receivers are calculated and by using these formulas, closed form expression for average level crossing rate of macrodiversity SC receiver output signal is evaluated. Average fade duration of proposed macrodiversity system can be calculated as ratio of outage probability and level crossing rate. By using obtained results the influence of Nakagami-m multipath fading severity parameter, Gamma shadowing severity parameter and shadowing correlation parameter on average level crossing rate is analyzed and discussed.

FIRST ORDER OUTAGE STATISTICS OF ASYMMETRICAL RF-OW DUAL-HOP RELAY COMMUNICATIONS