Munzur University

This study proposes a novel two-dimensional (2D) discrete hyperchaotic map derived from the analytical gradient components of the Bohachevsky-f3 benchmark function and an FPGA-based pseudorandom number generator (PRNG) based on this map. The dynamic behavior of the proposed map is investigated using phase-space, the Lyapunov exponent spectrum, initial-condition sensitivity, permutation entropy, correlation dimension, and the chi-square goodness-of-fit test. Two positive Lyapunov exponents (LEs) and a permutation entropy of approximately 0.9997 demonstrate that the system exhibits high dynamic complexity and hyperchaotic behavior over a wide range of the control parameter. The map is physically implemented on an Intel Cyclone IV Field-Programmable Gate Array (FPGA) using a parallel and pipelined architecture based on IEEE-754 single-precision 32-bit floating-point arithmetic. Two different extraction scenarios, namely threshold-based and byte-based approaches, are developed on the same hyperchaotic core for random-bit generation. The byte-based Scenario 2 generates 16 bits per 80-clock-cycle iteration, achieving an output bit rate of 30 Mbit/s at 150 MHz. This corresponds to an eightfold increase in output bit rate compared with Scenario 1. In this scenario, 11,966 logic elements, 6230 registers, and 73 embedded multiplier units are utilized, while the total power consumption and energy consumption per bit are estimated as 146.55 mW and 4.89 nJ/bit, respectively. The successful completion of the NIST SP 800–22 tests by the FPGA outputs and the 99.4% success rate achieved by Scenario 2 in TestU01 support the statistical reliability of the proposed architecture. The results confirm that the proposed hyperchaotic system and hardware design framework provide a feasible solution for secure communications, embedded systems, hardware-based cryptography, and various engineering applications.

Global water scarcity driven by population growth, climate variability, and rising freshwater demand increases the need for more efficient solar desalination systems. In this study, a double-slope solar distillation device supported by a phase change material pool was developed to improve freshwater production. The phase change material layer was placed directly beneath the absorber plate to store excess thermal energy during peak solar radiation and release it during low-radiation periods. To strengthen thermal interaction between the absorber surface and the storage medium, cylindrical fins were embedded within the phase change material pool. The development of a double-slope solar distillation device integrated with a finned phase change material pool, and the simultaneous comparison of the thermal efficiency and economic analyses of single-slope and double-slope solar distillation devices under the same climatic conditions, are the prominent features of this study. Additionally, the performance of solar distillation devices has not previously been investigated under the climatic conditions of Tunceli, which further motivates this research. The developed system reached a peak freshwater productivity of 2459.2 g/m2/day, providing a 21.4% enhancement over the conventional configuration. In addition, the thermal efficiency increased from 17.7% in the conventional unit to 21.4% in the phase change material-assisted design. The economic analysis showed that the cost of distilled water was $0.097/kg for the conventional system and $0.105/kg for the proposed system, with the corresponding payback periods being approximately 11 and 12 months, respectively.

The aim of this study is to assess the mechanical, physical and durability properties of environmentally friendly self-compacting mortars produced using materials containing industrial waste and natural stone. The test series were produced by substituting diatomite (D) and C class fly ash (F) with Portland cement (PC) up to 30% by weight. To evaluate the workability, mechanical and durability properties of self-compacting mortars (SCM), a total of 19 series, one of which was a reference sample, were prepared. The samples, whose mechanical properties and durability properties were investigated under sulphate attack and freeze-thaw effects, were prepared as 40 & times; 40 & times; 160 mm, and the series, whose physical properties were examined, were prepared as 50 & times; 50 & times; 50 mm. Also, SEM/EDS (Scanning Electron Microscope - Energy Dispersive X-Ray) and XRD (X-Ray Diffraction) analyses were carried out to evaluate the microstructural properties of the mixtures. When the 90-day compressive strength results were examined, it was determined that the highest decrease in compressive strength compared to the control sample occurred in the D20F10 sample with a rate of 61%, and the least decrease occurred in the D5 series with a rate of 10%. When the losses in compressive strength were evaluated after 50 freeze-thaw cycles, it was determined that there was a 100% reduction in the binary and ternary series containing D15 and D20. After six months of sulphate exposure, the D5F25 sample exhibited the most significant compressive strength reduction at roughly 40%, whereas the D15F15 series experienced the least compressive strength decline at around 5%.

Copper-based hybrid metal matrix composites reinforced with graphene and zinc were developed to achieve a balanced combination of mechanical strength, corrosion resistance, wear performance, and electrical conductivity. In this study, Cu matrix composites containing a constant graphene content of 1 wt.% and varying Zn contents (0, 5, 10, and 15 wt.%) were fabricated through mechanical alloying followed by Spark Plasma Sintering (SPS). The effects of zinc content on microstructure, densification, hardness, corrosion behavior, tribological performance, and electrical conductivity were systematically investigated. Microstructural analyses revealed that the combined use of graphene and Zn significantly influenced grain refinement, interfacial stability, and densification behavior. The composite containing 10 wt.% Zn exhibited the highest relative density (similar to 90.5%) and maximum hardness (62 HB), indicating an optimal reinforcement level. Corrosion tests conducted in 3.5 wt.% NaCl solution demonstrated that the 10 wt.% Zn composite showed the most noble corrosion potential and the lowest corrosion current density, which was attributed to reduced porosity and improved microstructural homogeneity. Tribological results confirmed that graphene contributed to a self-lubricating effect, while Zn enhanced load-bearing capacity, leading to improved wear resistance under increasing normal loads. Electrical conductivity measurements showed a gradual decrease with increasing Zn content, mainly due to solid-solution-induced electron scattering in the Cu matrix; however, the fixed graphene addition and effective SPS consolidation helped preserve conductive pathways, allowing all composites to retain acceptable conductivity levels. The results indicate that the hybrid Cu-graphene-Zn composites exhibit a balanced combination of mechanical, corrosion, tribological, and electrical properties, with 10 wt.% Zn emerging as the optimal composition.

The design of an effective battery thermal management system is critical to ensure the safe, efficient, and long-lasting operation of lithium-ion batteries. Excessive heat generation and temperature non-uniformity among cells in high energy density battery systems lead to performance degradation, accelerated aging, and an increased risk of thermal runaway. Although liquid-cooled systems and thermoelectric module-assisted solutions have been extensively investigated separately in the literature, studies that holistically evaluate multiple thermoelectric stations combined with an innovative flow channel design and turbulator integration remain limited. This gap constitutes a significant research need, particularly in terms of improving temperature uniformity and reducing maximum cell temperature. In this study, to address this research gap, a novel liquid-cooled battery thermal management system integrating thermoelectric coolers and turbulators within the flow channel is proposed. The thermal performance of the proposed system was systematically analyzed using computational fluid dynamics under three different configurations (conventional system, thermoelectric-assisted system, and turbulator-integrated thermoelectric-assisted system) and four different mass flow rates (0.0008, 0.0013, 0.0018, and 0.0023 kg/s). The results indicate that, at a mass flow rate of 0.0023 kg/s, the integration of thermoelectric coolers and turbulators reduces the maximum battery temperature by 8.95 K and the maximum temperature difference by 6.83 K. At the highest mass flow rate, the proposed system achieves a maximum battery temperature of 306 K and a maximum temperature difference of 4.5 K, ensuring both effective cooling performance and high temperature uniformity. Overall, the results in terms of cooling performance and temperature uniformity demonstrate that the combination of thermoelectric modules and turbulators offers significant potential for advanced battery thermal management system applications and offers an effective solution for high-energy-density systems.