a compact printed fractal antipodal bow-tie antenna is designe d and implemented to simultaneously cover the operations in the C, X, a nd Ku-bands. It is demonstrated that by addition of small fractal elemen ts at the sides of hexagonal arms of the bow-tie, a wide operating freque ncy range of 3. 3 to 19. 1 GHz can be covered while antenna size is only 3 0×34×1. 2 mm3. In order to match the antenna to the 50Ù SMA connecto r, a multi-section microstrip line of different widths is designed. The sim ulation results obtained from HFSS simulator package are verified by e xperimental measurements. Measured data are in good agreement with the simulated results. The frequency-and time-domain characteristics o f the antenna including impedance matching, far-field patterns, radiatio n efficiency, gain, and fidelity factor are presented and discussed. The p roposed antenna features 141% impedance bandwidth (defined by-10-d B reflection coefficient), small size, and desirable radiation patterns that make it excellent candidate for integration in broadband array systems.

To address radiative heat transfer problems, the determination of view factors is crucial. In this study, the focus is placed on the calculation of the view factor using the Monte Carlo method, specifically for truncated cone radiators. Although reference books offer theoretical relations for computing the view factor, a new approach employing the Monte Carlo method is utilized to ensure the accuracy of the general solution. To measure the accuracy, three types of cases are considered: positive, negative, and zero-angle truncated cones with a fixed disk (ring) at the base of the cone. The results are presented for various ratios between the height of the truncated cone and the radii of the ring and base side of the cone. Additionally, the impact of different angles of the truncated cone on the view factor is investigated. In the zero-angle case, five different L/r1 are examined, in the positive angle case, seven different positive angles in two different L/r1 are studied, and in the negative angle case, three negative angles in three different L/r1 are studied. For positive angles, the maximum difference between the results of Monte Carlo method and theoretical method is 42.81% and occurred in L/r1 equal to 5 and 40 degrees. While for zero-angle the maximum difference is 30.16% and occurred in L/r1 equal to 10. In the negative angle case, the maximum difference is 36.66% and occurred in L/r1 equal to 0.2 and -15 degrees.

The purpose of this study is to investigate the effectiveness of turbulence promoters—spring, twisted tape, and propeller—in reducing sediment accumulation within domestic heating radiators, a challenge that impacts thermal efficiency and system longevity. The research involved a 72-hour experimental analysis under controlled conditions, using a dual-radiator setup to evaluate the performance of each turbulator type at various temperature. The study adhered to international standards, ensuring the reliability and replicability of the results. Methodologically, the turbulator geometries were selected to maximize shear stress and compatibility with the radiator dimensions, with the aim of achieving optimal sediment reduction without compromising thermal efficiency. The experiments measured key parameters, including heat output, pressure drop, and the weight of residual particles, to validate the turbulator's effectiveness. The results revealed that the propeller turbulator was particularly effective, reducing the heat output reduction due to sedimentation to 5.1% at a Reynolds number of 1680, compared to an 18.3% reduction in the control system without a turbulator. Additionally, the introduction of turbulators resulted in a minimal increase in the pressure drop, demonstrating their efficiency in sediment control without negatively impacting hydraulic performance. The weight of residual particles was significantly lower in systems using turbulators, with the propeller showing the greatest reduction. The study concludes that mechanical turbulence promoters, especially the propeller, provide a sustainable alternative to chemical methods that can cause corrosion and reduce the durability of radiators. These findings contribute to the development of more efficient and long-lasting domestic heating systems, aligning with the broader goals of advancing residential thermal management.

radiators are among the essential parts of car engines, and any weakness or defect in them can cause severe damage to the engine. The most critical tasks of radiators is effective heat transfer between air and fluid inside the radiator tubes, which is done by fans. Since the air temperature has a direct relationship with its pressure, measuring the air pressure before and after the radiator is necessary. In this research, three different methods have been used to calculate the air pressure drop at speeds of 3, 5, and 8 m/s. The purpose of this work is to introduce the best possible method to reduce the risks that are caused by the wrong reading of the air pressure drop using the accuracy of the obtained results, The point that each part of the radiator is determined by which pressure (static or dynamic pressure) is crucial and plays an essential role for choosing better type of pressure gauge. If this is done, the obtained results will be correct. If the air pressure drop is not calculated correctly, it can cause severe damage to the engine and other car parts. The best method that has the slightest error and the least risk for car radiators is when the pressure gauge calculates the static pressure inside the wind tunnel and the dynamic pressure outside the wind tunnel. In this case, the error of the obtained results comparing to the standard results is 9. 16, 15. 41 and 10. 18%, at speeds of 3, 5 and 8.

radiators are among the essential parts of car engines, and any weakness or defect in them can cause severe damage to the engine. The most critical tasks of radiators is effective heat transfer between air and fluid inside the radiator tubes, which is done by fans. Since the air temperature has a direct relationship with its pressure, measuring the air pressure before and after the radiator is necessary. In this research, three different methods have been used to calculate the air pressure drop at speeds of 3, 5, and 8 m/s. The purpose of this work is to introduce the best possible method to reduce the risks that are caused by the wrong reading of the air pressure drop using the accuracy of the obtained results, The point that each part of the radiator is determined by which pressure (static or dynamic pressure) is crucial and plays an essential role for choosing better type of pressure gauge. If this is done, the obtained results will be correct. If the air pressure drop is not calculated correctly, it can cause severe damage to the engine and other car parts. The best method that has the slightest error and the least risk for car radiators is when the pressure gauge calculates the static pressure inside the wind tunnel and the dynamic pressure outside the wind tunnel. In this case, the error of the obtained results comparing to the standard results is 9. 16, 15. 41 and 10. 18%, at speeds of 3, 5 and 8.

In this paper, experimental and numerical comparison of Baseboard radiator and Panel radiator are presented. Rated capacity of both radiators was 1200 kcal per hour. In the experimental section, at the same ambient temperature for both radiators, capacity and characteristic equation and temperature distribution in a room with dimensions of 2. 6 × 4 × 4 meter was obtained. The experimental results showed that a Uniform Temperature distribution occurs in the room for the Baseboard radiator, Temperature difference in vertical direction for center of the room for the Panel radiator in various capacities changes 3° C to 7° C, While for the Baseboard radiator at all capacities temperature difference was about 2 ° C. Temperature difference at height of 1. 5 m in horizontal direction from wall that the Panel radiator was installed to facing wall, changes 3° C to 6° C. While for the Baseboard radiator, this result was about 0. 5° C. To investigate the cause of the temperature distribution, numerical modeling was used. Numerical results and experimental results were close with 10% error. Temperature distribution curves At plane of symmetry room for both samples was drawn, Baseboard radiators were more uniform temperature distribution again. In the end, the velocity distribution diagram in the vertical plane of symmetry room was obtained which show that a strong circulation occurs in the room for the Baseboard radiator.

‎The adjacency matrix is important invariant of a graph with a chemical meaning‎, ‎when we study the chemical graphs‎. ‎In this paper‎, ‎the general form of the adjacency matrices of some hexagonal systems will be determined‎.

In recent years, there has been a growing interest in the use of plasmonic nanoparticles as sources of heat remotely controlled by light, giving rise to the field of thermoplasmonics. To this end, gold nanoframes are unique nanomaterials with the intrinsic capability to generate a nanoscale confined light-triggered thermal effect. Therefore, the plasmonic and thermoplasmonic properties of the gold hexagonal nanoframes have been investigated in this paper. Moreover, the effect of some influential parameters such as gap distance between the two nanoparticles and the distance between the center of the cavities and the center of the nanoframes on the local electric field and the surface temperature of the nanoframes have been reported

In this investigation, we present pioneering findings on the detrimental effects of sediment deposits on the thermal and hydraulic performance of residential heating radiators through a novel experimental framework. Our approach, through the systematic introduction of particulate matter into the water circuit, quantifies the real-world impact of sediment accumulation. This methodology fills a significant void in literature with validated experimental data and establishes a method for assessing radiator performance under fouled conditions, adhering to ISO 3148 standards. The experimental results underscore a significant efficiency downturn: sediment presence increased pressure drop by up to 10.5% and reduced surface temperature by as much as 13%. Notably, heat output initially saw a slight increase, only to decrease by up to 28.5% over time, with these effects amplifying at higher inlet temperatures. These findings underscore the urgent need for tailored maintenance strategies to combat sediment-related degradation, offering invaluable insights for the design, maintenance, and optimization of heating systems beneficial to both industry stakeholders and end-users.