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In the extreme space environment, spacecraft endure dramatic temperature variations that can impair their functionality. A VO2-based smart radiator device (SRD) offers an effective solution by adaptively adjusting its radiative properties. However, current research on VO2-based thermochromic films mainly focuses on optimizing the emissivity tunability (Δε) of single-cycle sandwich structures. Although multi-cycle structures have shown increased Δε compared to single-cycle sandwich structures, there have been few systematic studies to find the optimal cycle structure. This paper theoretically discusses the influence of material properties and cyclic structure on SRD performance using Finite-Difference Time-Domain (FDTD) software, which is a rigorous and powerful tool for modeling nano-scale optical devices. An optimal structural model with maximum emissivity tunability is proposed. The BaF2 obtained through optimization is used as the dielectric material to further optimize the cyclic resonator. The results indicate that the tunability of emissivity can reach as high as 0.7917 when the BaF2/VO2 structure is arranged in three periods. Furthermore, to ensure a longer lifespan for SRD under harsh space conditions, the effects of HfO2 and TiO2 protective layers on the optical performance of composite films are investigated. The results show that when TiO2 is used as the protective layer with a thickness of 0.1 µm, the maximum emissivity tunability reaches 0.7932. Finally, electric field analysis is conducted to prove that the physical mechanism of the smart radiator device is the combination of stacked Fabry-Perot resonance and multiple solar reflections. This work not only validates the effectiveness of the proposed structure in enhancing spacecraft thermal control performance but also provides theoretical guidance for the design and optimization of SRDs for space applications.

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Contact burns in children are not uncommon and are often due to accidental contact. Medico-legal assessment is of paramount importance in these contexts to identify cases of abuse. In three cases of burns caused by contact with radiators or a portable heater -two accidental and one deliberate- thorough medico-legal assessment, combined with on-site event reconstruction, enabled accurate diagnoses. Accidental burns displayed a 'pattern' compatible with the incandescent instrument but were more irregular, with different depths and in different parts of the body. In contrast, intentional burns were uniform in depth, distribution and localisation, inconsistent with accidental events. In this context, the on-site inspection and direct evaluation of the objects involved were crucial in the medico-legal assessment. These are indispensable elements for a thorough analysis and abuse recognition.

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80% of current UK housing stock is expected to still be in use in 2050. Difficult, intrusive and expensive, refurbishment measures are required to achieve the level of insulation required for current low temperature heat pumps. Transcritical CO2 heat pumps can achieve higher efficiencies, with higher output temperatures, than current, Carnot limited, synthetic gas heat pumps, with less environmental impact. Widely deployed in water heating and supermarket chilling systems, CO2 heat pumps need heating return temperatures of 30 °C or less to function effectively. This has impeded their adoption with hydronic heating systems which have high return temperatures. This study identified system modifications external to the refrigeration cycle that address return temperatures. It modelled a transcritical CO2 air source heat pump with a hydronic heating system in a solid wall semi-detached house. Full year system coefficients of performance over 3 were achieved in four UK locations by using space heating return fluids to defrost the air source heat exchanger and to pre-heat inlet water, recovering any remaining excess return fluid heat as a source for the heat pump. Solar panels boosted this to 5.1. The levelized cost of energy for the system was calculated (with heat pump grant) at 22p/kWh, lower than a gas boiler, with 9.45 tonnes CO2 emission savings over a fifteen-year life.

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The circular waveguide aperture or open-end radiator, one of the canonical antenna elements, can be filled with a dielectric material for miniaturization. With dielectric filling, the aperture reflection increases and impedance matching is necessary. This paper presents a simple but innovative simulation-based approach to the aperture matching of a dielectric-filled circular waveguide aperture. By properly loading the aperture with two- or three-section dielectric rings, the impedance matching is possible over a wide frequency range starting slightly above the TE11-mode cutoff and continuing upward. The material for the aperture matching is the same as that filling the waveguide. The proposed matching structure is analyzed and optimized using a simulation tool for the dielectric constant εr of the filling material ranging from 1.8 to 10. For εr ≥ 5, the unmatched reflection coefficient ranges from -6.0 dB to -0.9 dB while the matched reflection coefficient is from -20.4 dB to -10.0 dB. The impedance matching has been achieved over more than an octave bandwidth.

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In this article, a miniature eight-port multiple-input multiple-output (MIMO) antenna array is proposed for fifth-generation (5G) sub-6 GHz handset applications. The individual antenna element comprises a radiator shaped like the Chinese character "" (phonetically represented as "Wang") and three split-ring resonators (SRR) on the metal frame. The size of the individual antenna element is only 6.8 × 7 × 1 mm3 (47.6 mm3). The proposed antenna element has a -10 dB impedance bandwidth of 1.7 GHz (from 3.3 GHz to 5 GHz) that can cover 5G New Radio (NR) sub-6 GHz bands N77 (3.3-4.2 GHz), N78 (3.3-3.8 GHz), and N79 (4.4-5 GHz). The evolution design, the current distribution, the effects of single-handed holding, and the analysis of the parameters are deduced to study the approach used to design the featured antenna. The measured total efficiencies are from 40% to 80%, the isolation is better than 12 dB, the calculated envelope correlation coefficient (ECC) is less than 0.12, and the calculated channel capacity (CC) ranges from 35 to 38 bps/Hz. The presented antenna array is a good alternative to 5G mobile handsets with wideband operation, a metal frame, and minimized spacing.

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Radiator reliability is crucial in environments characterized by high temperatures and friction, where prompt interventions are often required to prevent system failures. This study introduces a proactive approach to radiator fault diagnosis, leveraging the integration of the Gaussian Mixture Model and Long-Short Term Memory autoencoders. Vibration signals from radiators were systematically collected through randomized durability vibration bench tests, resulting in four operating states-two normal, one unknown, and one faulty. Time-domain statistical features of these signals were extracted and subjected to Principal Component Analysis to facilitate efficient data interpretation. Subsequently, this study discusses the comparative effectiveness of the Gaussian Mixture Model and Long Short-Term Memory in fault detection. Gaussian Mixture Models are deployed for initial fault classification, leveraging their clustering capabilities, while Long-Short Term Memory autoencoders excel in capturing time-dependent sequences, facilitating advanced anomaly detection for previously unencountered faults. This alignment offers a potent and adaptable solution for radiator fault diagnosis, particularly in challenging high-temperature or high-friction environments. Consequently, the proposed methodology not only provides a robust framework for early-stage fault diagnosis but also effectively balances diagnostic capabilities during operation. Additionally, this study presents the foundation for advancing reliability life assessment in accelerated life testing, achieved through dynamic threshold adjustments using both the absolute log-likelihood distribution of the Gaussian Mixture Model and the reconstruction error distribution of the Long-Short Term Memory autoencoder model.

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As UWB technology develops and devices become smaller, miniaturization techniques for an array antenna system are required. In addition, more in-depth research is needed for UWB direction-finding techniques using channel impulse response (CIR) data. This paper proposes an ultra-wideband (UWB) antenna using a single-radiator multiple-port (SRMP) design for the direction-finding systems of smart devices. The proposed SRMP antenna was designed using a single tripod-shaped patch that can replace the array system. The tripod-shaped radiator was optimized using the edge shape design function to improve its broadband and mutual coupling characteristics. For performance verification, the proposed antenna was fabricated, and the reflection coefficient, mutual coupling, and radiation patterns were measured in a fully anechoic chamber. The proposed antenna has an operating frequency band of 6.1 GHz (from 5.8 GHz to 11.9 GHz) for port 1 and a measured mutual coupling of -14.8 dB at 8 GHz. The SRMP antenna has measured maximum gains of 3.5 dBi for port 1 and 2.9 dBi for port 2. To examine the direction-finding performance, the fabricated antenna was connected to a circuit module with a DW3000 chip, which is widely employed in commercial mobile UWB systems. The direction of arrival (DoA) results using the measured CIR data show root-mean-square (RMS) errors of 1.57° and 4.58° at distances of 30 cm and 60 cm.

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The maximum reflection at an open end of a standard rectangular waveguide is about -10 dB in its operating frequency range. It is often used without matching. For critical applications, it is desirable to further reduce the reflection coefficient. In this paper, a new technique is presented for the broadband impedance matching of an open-ended rectangular waveguide. The proposed technique employs three thin capacitive matching elements placed at proper intervals via a low-loss dielectric material. The capacitance of, and distance between, the matching elements are optimized for broadband impedance matching using a simulation tool. Based on the proposed technique, two design examples are presented for the matching of a WR75 waveguide radiator. A reflection coefficient of less than -16 dB and -20 dB has been achieved over a ratio bandwidth of 2.13:1 and 1.62:1, respectively.

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This study aims to design a compact antenna structure suitable for implantable devices, with a broad frequency range covering various bands such as the Industrial Scientific and Medical band (868-868.6 MHz, 902-928 MHz, 5.725-5.875 GHz), the Wireless Medical Telemetry Service (WMTS) band, a subset of the unlicensed 3.5-4.5 GHz ultra-wideband (UWB) that is free of interference, and various Wi-Fi spectra (3.6 GHz, 4.9 GHz, 5 GHz, 5.9 GHz, 6 GHz). The antenna supports both low and high frequencies for efficient data transfer and is compatible with various communication technologies. The antenna features an asynchronous-meandered radiator, a parasitic patch, and an open-ended square ring-shaped ground plane. The antenna is deployed deep inside the muscle layer of a rectangular phantom below the skin and fat layer at a depth of 7 mm for numerical simulation. Furthermore, the antenna is deployed in a cylindrical phantom and bent to check the suitability for different organs. A prototype of the antenna is created, and its reflection coefficient and radiation patterns are measured in fresh pork tissue. The proposed antenna is considered a suitable candidate for implantable technology compared to other designs reported in the literature. It can be observed that the proposed antenna in this study has the smallest volume (75 mm3) and widest bandwidth (181.8% for 0.86 GHz, 9.58% for 1.43 GHz, and 285.7% for the UWB subset and Wi-Fi). It also has the highest gain (-26 dBi for ISM, -14 dBi for WMTS, and -14.2 dBi for UWB subset and Wi-Fi) compared to other antennas in the literature. In addition, the SAR values for the proposed antenna are well below the safety limits prescribed by IEEE Std C95.1-1999, with SAR values of 0.409 W/Kg for 0.8 GHz, 0.534 W/Kg for 1.43 GHz, 0.529 W/Kg for 3.5 GHz, and 0.665 W/Kg for 5.5 GHz when the applied input power is 10 mW. Overall, the proposed antenna in this study demonstrates superior performance compared to existing tri-band implantable antennas in terms of size, bandwidth, gain, and SAR values.

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In the upcoming years, it is expected that more furniture will be built from honeycomb panels due to the growing demand for lightweight, long-lasting furnishings. High-density fiberboard (HDF), previously used in the furniture industry as back walls in box furniture or drawer components, has become a popular facing material used in the production of honeycomb core panels. Varnishing the facing sheets of lightweight honeycomb core boards with the use of analog printing technology and UV lamps is a challenge for the industry. The aim of this study was to determine the effect of selected varnishing parameters on coating resistance by experimentally testing 48 coating variants. It was found that the interactions between the following variables were crucial in achieving adequate resistance: lamp power, the amounts of varnish applied, and the number of layers. The highest scratch, impact, and abrasion resistance values were observed for samples with optimal curing provided by more layers and maximum curing with 90 W/cm lamps. Based on the pareto chart, a model was generated that predicted the optimal settings for the highest scratch resistance. Resistance to cold liquids made with a colorimeter increases with lamp power.

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A radiator is used to remove a portion of the heat generated by a vehicle engine. It is challenging to efficiently maintain the heat transfer in an automotive cooling system even though both internal and external systems need enough time to keep pace with catching up with evolving engine technology advancements. The effectiveness of a unique hybrid's heat transfer nanofluid was investigated in this study. The hybrid nanofluid was mainly composed of graphene nanoplatelets (GnP), and cellulose nanocrystals (CNC) nanoparticles suspended in a 40:60 ratio of distilled water and ethylene glycol. A counterflow radiator equipped with a test rig setup was used to evaluate the hybrid nano fluid's thermal performance. According to the findings, the proposed GNP/CNC hybrid nanofluid performs better in relation to improving the efficiency of heat transfer of a vehicle radiator. The suggested hybrid nanofluid enhanced convective heat transfer coefficient by 51.91%, overall heat transfer coefficient by 46.72%, and pressure drop by 34.06% with respect to distilled water base fluid. Additionally, the radiator could reach a better CHTC with 0.01% hybrid nanofluid in the optimized radiator tube by the size reduction assessment using computational fluid analysis. In addition to downsizing the radiator tube and increasing cooling capacity over typical coolants, the radiator takes up less space and helps to lower the weight of a vehicle engine. As a result, the suggested unique hybrid graphene nanoplatelets/cellulose nanocrystal-based nanofluids perform better in heat transfer enhancement in automobiles.

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This manuscript examines the design principle and real-world validation of a new miniaturized high-performance flower-shaped radiator (FSR). The antenna prototype consists of an ultracompact square metallic patch of 0.116λ0 × 0.116λ0 (λ0 is the free space wavelength at 3.67 GHz), a rectangular microstrip feed network, and a partial metal ground plane. A novel, effective, and efficient approach based on open circuit loaded stubs is employed to achieve the antenna's optimal performance features. Rectangular, triangular, and circular disc stubs were added to the simple structure of the square radiator, and hence, the FSR configuration was formed. The proposed antenna was imprinted on a low-cost F4B laminate with low profile thickness of 0.018λ0, relative permittivity εr = 2.55, and dielectric loss tangent δ = 0.0018. The designed radiator has an overall small size of 0.256λ0 × 0.354λ0. The parameter study of multiple variables and their influence on the performance results has been extensively studied. Moreover, the impact of different substrate materials, impedance bandwidths, resonance tuning, and impedance matching has also been analyzed. The proposed antenna model has been designed, simulated, and fabricated. The designed antenna exhibits a wide bandwidth of 5.33 GHz ranging from 3.67 to 9.0 GHz at 10 dB return loss, which resulted in an 83.6% fractional impedance bandwidth; a maximum gain of 7.3 dBi at 8.625 GHz; optimal radiation efficiency of 89% at 4.5 GHz; strong intensity current flow across the radiator; and stable monopole-like far-field radiation patterns. Finally, a comparison between the scientific results and newly published research has been provided. The antenna's high-performance simulated and measured results are in a good agreement; hence, they make the proposed antenna an excellent choice for modern smartphones' connectivity with the sub-6 GHz frequency spectrum of modern fifth-generation (5G) mobile communication application.

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Force measurement is a science discipline that experiences significant progress with the introduction of new materials and evaluation methods. Many different sensor types, working on different principles, have been developed and reviewed and have found use in medicine as well as many other industries. New trends and demands require a size reduction and simple applicability, with the use of, for example, micro electromechanical systems (MEMS). For purposes of this study, the initial MEMS body is supplemented by its scaled version. Force measurement in this study works on the force to time-delay conversion principle. A compact compliant mechanical body (CCMB) with an embedded parallel resonant circuit (PRC) acting as a transducer realizes the conversion. Depending on the resonant frequency of the transducer (CCMB or MEMS), we have measured the applied force based on the reverse influence of the transducer on the surrounding EM field. The analysis shows that the transducer's resonant frequency has a detectable reverse influence on the voltage-controlled oscillator (VCO) DC supply current. The force influencing the transducer is determined by the DC supply current ripple position during the VCO frequency sweep. The study presents the method proposal and mathematical analysis, as well as its function verification by simulation and prototype measurements. The proposed principle was validated on a CCMB prototype capable of measuring forces up to ∼2.5 N at a sampling frequency of ∼23 kHz, while the measured time-delay ranges from 14.5 µs to 27.4 µs.

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In response to the increasing demand for voice, data, and multimedia applications, the next generation of wireless communication systems is projected to provide faster data rates and better service quality to customers. Techniques such as Multiple-Input-Multiple-Output (MIMO) and diversity are being studied and implemented to meet the needs of next-generation wireless communication systems. Embedding multiple antennas into the same antenna system is seen as a promising solution, which can improve both the system's channel capacity and the communication link's quality. However, for small handheld and portable devices, embedding many antennas into a single device in a small area and at the same time providing good isolation becomes a challenge. Hence, designing a shared antenna system with multiple feed ports with equivalent or better performance characteristics as compared to the approach of multiple antennas with multiple feed ports is a promising advantage which can reduce the size and cost of manufacturing. This paper intends to provide an in-depth review of different MIMO antenna designs with common radiators covering various antenna design aspects such as isolation techniques, gain, efficiency, envelope correlation coefficient, and size, etc. There is also a discussion of the mathematical concepts of MIMO and different isolation techniques, as well as a comparative analysis of different shared radiator antenna designs. The literature review shows that only very few antennas' design with common radiator have been suggested in the available literature at present. Therefore, in this review paper, we have endeavored to study different antennas' designs with common radiator. A comparison is provided of their performance improvement techniques in a holistic way so that it can lead to further develop the common radiator multiport antenna systems and realize the promising advantages they offer.

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As electronic components progressively downsize and their power intensifies, thermal management has emerged as a paramount challenge. This study presents a novel, high-efficiency finned heat exchanger, termed Flat-Plate Oscillating Heat Pipe Finned Radiator (FOHPFR), which employs arrayed flat-plate oscillating heat pipes (OHP) as heat dissipation fins. Three-dimensional (3D)-printed techniques allow the internal microchannels of the FOHPFR to become rougher, providing excellent surface wettability and capillary forces, which in turn significantly improves the device's ability to dissipate heat. In this study, the 3D-printed FOHPFR is compared with traditional solid finned radiators made of identical materials and designs. The impacts of filling ratio, inclination angle, and cold-end conditions on the heat transfer performance of the 3D-printed FOHPFR are investigated. It is demonstrated by the results that compared to solid finned radiators, the FOHPFR exhibits superior transient heat absorption and steady-state heat transfer capabilities. When the heating power is set at 140 W, a decrease in thermal resistance from 0.32 °C/W in the solid type to 0.11 °C/W is observed in the FOHPFR, marking a reduction of 65.6%. Similarly, a drop in the average temperature of the heat source from 160 °C in the solid version to 125 °C, a decrease of 21.8%, is noted. An optimal filling ratio of 50% was identified for the vertical 3D-printed FOHPFR, with the minimal thermal resistance achieving 0.11 °C/W. Moreover, the thermal resistance of the 3D-printed FOHPFR is effectively reduced compared to that of the solid finned radiator at all inclination angles. This indicates that the FOHPFR possessed notable adaptability to various working angles.

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Thermochromic vanadium dioxide (VO2)-based smart radiator devices (SRDs) display emittance variation with changes in temperature, making them very promising for energy-efficient thermal control of spacecrafts in general, and nanosatellites in particular. However, the high solar absorptance of the VO2-based SRDs remains too high for their intended application. Based on an approach combining optical simulation and experimental work, I demonstrate that an additional top stack layer alternating between high and low refractive indices made of a-Si(25 nm)/SiO2(67 nm) reduces the solar absorptance of a VO2-based SRD by 35% (from 0.43 to 0.28) while keeping the emittance performance of the SRD within the requirements for the intended application (low-temperature emittance εL = 0.35, high-temperature emittance εH = 0.81 and emittance tuneability with temperature Δε = 0.46). I also discuss factors to consider while designing additional top stack layers alternating between high and low refractive indices to further decrease the SRD's solar absorptance without affecting its emittance performance.

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Pure aluminum radiator is the best choice for heat dissipation of various LED products at present. Its forming methods include common extrusion, die casting, forging, etc. Compared with other forming technologies, the LED radiator formed by cold forging has good heat dissipation performance, but there are some disadvantages in the forming process, such as uneven deformation, large material consumption and low die life. The cold forging process of pure aluminum fin-typed LED radiator is analyzed by the finite element method. The calculation results show that equal fillet structure of concave die is improper, leading to serious uneven flow velocity distribution during aluminum forging, inconsistent fin length, and warpage tendency. The gradient fillet structure of concave die is adopted. Numerical simulation and production test show that the gradient fillet structure design can significantly reduce the uneven metal flow. The extruded fins have a uniform length, which is conducive to reducing subsequent machining and production cost.

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In this paper, we present a novel approach to direction-of-arrival (DoA) estimation using two-row electronically steerable parasitic array radiator (ESPAR) antenna which has 12 passive elements and allows for elevation and azimuth beam switching using a simple microcontroller, relying solely on received signal strength (RSS) values measured at the antenna output port. To this end, we thoroughly investigate all 18 available 3D antenna radiation patterns of the antenna measured in an anechoic chamber with respect to radiation coverage in the horizontal and vertical direction and propose a generalization of the power-pattern cross-correlation (PPCC) algorithm involving a high number of multiple calibration planes (MCP) as well as specific combinations of radiation pattern sets. Additionally, a new way of RSS-based DoA estimation accuracy assessment, which involves thorough testing conducted along the elevation direction when RF signals impinging on the antenna arrive from arbitrary θ angles, has been reported in this paper to verify the overall algorithm's performance. The results obtained for different signal-to-noise ratio (SNR) levels indicate that two-row ESPAR antenna can produce, even for low SNR values, accurate DoA estimation in the horizontal plane without prior knowledge about the elevation direction of the unknown RF signals by using appropriate combinations of only 12 3D antenna radiation patterns.

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This paper investigates and develops a novel compact broadband and radiation efficient antenna design for the medical internet of things (M-IoT) healthcare system. The proposed antenna comprises of an umbrella-shaped metallic ground plane (UsMGP) and an improved radiator. A hybrid approach is employed to obtain the optimal results of antenna. The proposed solution is primarily based on the utilization of etching slots and a loaded stub on the ground plane and rectangular patch. The antenna consists of a simple rectangular patch, a 50 Ƹ microstrip feed line, and a portion of the ground plane printed on a relatively inexpensive flame retardant material (FR4) thick substrate with an overall compact dimension of 22 × 28 × 1.5 mm3. The proposed antenna offers compact, broadband and radiation efficient features. The antenna is carefully designed by employing the approximate calculation formulae extracted from the transmission line model. Besides, the parameters study of important variables involved in the antenna design and its influence on impedance matching performance are analyzed. The antenna shows high performance, including impedance bandwidth of 7.76 GHz with a range of 3.65Ƀ11.41 GHz results in 103% wider relative bandwidth at 10 dB return loss, 82% optimal radiation efficiency in the operating band, reasonable gain performance, stable monopole-shaped radiation patterns and strong current distribution across the antenna lattice. The suggested antenna is manufactured, and simulation experiments evaluate its performance. The findings indicate that the antenna is well suited for medical IoT healthcare systems applications.

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Three-dimensional (3D)-printed porous Ti6Al4V implants play an important role in the reconstruction of bone defects. However, its osseointegration capacity needs to be further improved, and related methods are inadequate, especially lacking customized surface treatment technology. Consequently, we aimed to design an omnidirectional radiator based on ultraviolet (UV) photofunctionalization for the surface treatment of 3D-printed porous Ti6Al4V implants, and studied its osseointegration promotion effects in vitro and in vivo, while elucidating related mechanisms. Following UV treatment, the porous Ti6Al4V scaffolds exhibited significantly improved hydrophilicity, cytocompatibility, and alkaline phosphatase activity, while preserving their original mechanical properties. The increased osteointegration strength was further proven using a rabbit condyle defect model in vivo, in which UV treatment exhibited a high efficiency in the osteointegration enhancement of porous Ti6Al4V scaffolds by increasing bone ingrowth (BI), the bone-implant contact ratio (BICR), and the mineralized/osteoid bone ratio. The advantages of UV treatment for 3D-printed porous Ti6Al4V implants using the omnidirectional radiator in the study were as follows: 1) it can significantly improve the osseointegration capacity of porous titanium implants despite the blocking out of UV rays by the porous structure; 2) it can evenly treat the surface of porous implants while preserving their original topography or other morphological features; and 3) it is an easy-to-operate low-cost process, making it worthy of wide clinical application.