Search Results (78)

Background/Objectives: Orbital reconstruction remains one of the most demanding procedures in maxillofacial surgery. It requires not only precise anatomical knowledge but also poses multiple intraoperative challenges. Limited surgical visibility—especially in transconjunctival or transcaruncular approaches—demands exceptional precision from the surgeon. At the same time, the complex anatomical structure of the orbit, its rich vascularization and innervation, and the risk of severe postoperative complications—such as diplopia, sensory deficits, impaired ocular mobility, or in the most serious cases, post-traumatic blindness due to nerve injury or orbital compartment syndrome—necessitate the highest level of surgical accuracy. In this context, patient-specific implants (PSIs), commonly fabricated from zirconium oxide or ultra-high-density polyethylene, have become invaluable. Within CAD-based reconstructive planning, especially for orbital implants, critical factors include the implant’s anatomical fit, passive stabilization on intact bony structures, and non-interference with orbital soft tissues. Above all, precise replication of the orbital dimensions is essential for optimal clinical outcomes. This study compares the morphological accuracy of orbital structures based on anthropometric measurements from 3D models generated from fan-beam computed tomography (FBCT) and cone-beam computed tomography (CBCT). Methods: A cohort group of 500 Caucasian patients aged 8 to 88 years was analyzed. 3D models of the orbits were generated from FBCT and CBCT scans. Anthropometric measurements were taken to evaluate the morphological accuracy of the orbital structures. The assessed parameters included orbital depth, orbital width, the distance from the infraorbital rim to the infraorbital foramen, the distance between the piriform aperture and the infraorbital foramen, and the distance from the zygomatico-orbital foramen to the infraorbital rim. Results: Statistically significant differences were observed between virtual models derived from FBCT and those based on CBCT in several key parameters. Discrepancies were particularly evident in measurements of orbital depth, orbital width, the distance from the infraorbital rim to the infraorbital foramen, the distance between the piriform aperture and the infraorbital foramen, and the distance from the zygomatico-orbital foramen to the infraorbital rim. Conclusions: The statistically significant discrepancies in selected orbital dimensions—particularly in regions of so-called thin bone—demonstrate that FBCT remains the gold standard in the planning and design of CAD/CAM patient-specific orbital implants. Despite its advantages, including greater accessibility and lower radiation dose, CBCT shows limited reliability in the context of orbital and infraorbital reconstruction planning. Full article

Cone-beam computed tomography (CBCT) offers low radiation, cross-sectional imaging that is a suitable alternative to conventional fan-beam computed tomography (FBCT). The initial experience using in-clinic CBCT in the Rhinology outpatient clinic at Waikato Hospital, New Zealand, is described. The first 5 months of CBCT use for Rhinologic imaging was compared to FBCT use in the equivalent 5-month period one year prior. Data relating to 61 CBCTs and 115 FBCTs was analysed. We compared the time and number of hospital visits required for a confirmed treatment decision (CTD) to be made and the duration of the clinic appointment at which the scan was requested between the two groups. The CBCT group required significantly less time (171 vs. 316 days, p < 0.001) and fewer hospital visits (1.5 vs. 3.2 visits, p < 0.001) before a CTD was made, but a longer appointment duration (86 vs. 53 min, p < 0.001). The use of in-clinic CBCT in Rhinology was therefore associated with reduced time and fewer hospital visits before definitive management was decided, but longer clinic appointments were observed. Increased access to CT imaging may result in increased demand. Expertise is required to optimise the quality of imaging, and we recommend that a dedicated Radiographer be allocated. Full article

Atmospheric turbulence introduces distortions to the wavefront of propagating optical radiation. It causes image resolution degradation in astronomical telescopes and significantly reduces the power density of radiation on the target in focusing applications. The impact of turbulence fluctuations on the wavefront can be investigated under laboratory conditions using either a fan heater (roughly tuned), a phase plate, or a deformable mirror (finely tuned) as a turbulence-generation device and a wavefront sensor as a wavefront-distortion measurement device. We designed and developed a software simulator and an experimental setup for the reconstruction of atmospheric turbulence-phase fluctuations as well as an adaptive optical system for the compensation of induced aberrations. Both systems use two 60 mm, 92-channel, bimorph deformable mirrors and two tip-tilt correctors. The wavefront is measured using a high-speed Shack–Hartmann wavefront sensor based on an industrial CMOS camera. The system was able to achieve a 500 Hz correction frame rate, and the amplitude of aberrations decreased from 2.6 μm to 0.3 μm during the correction procedure. The use of the tip-tilt corrector allowed a decrease in the focal spot centroid jitter range of 2–3 times from ±26.5 μm and ±24 μm up to ±11.5 μm and ±5.5 μm. Full article

As global mineral resources at shallow depths continue to deplete, thermal hazards have emerged as a critical challenge in deep mining operations. Conventional localized cooling systems suffer from a fundamental inefficiency where their cooling capacity is rapidly dissipated by the main ventilation airstream. This study introduces the innovative concept of a “microclimatic circulation zone” implemented through a convection–radiation cooling system. The design incorporates a synergistic arrangement of dual fans and flow-guiding baffles that creates a semi-enclosed air circulation field surrounding the modular convection–radiation cooling apparatus, effectively preventing cooling capacity loss to the primary ventilation flow. The research develops comprehensive theoretical models characterizing both internal and external heat transfer mechanisms of the modular convection–radiation cooling system. Using Fluent computational fluid dynamics software, we constructed an integrated heat–moisture–flow coupled numerical model that identified optimal operating parameters: refrigerant velocity of 0.2 m/s, inlet airflow velocity of 0.45 m/s, and outlet aperture height of 70 mm. Performance evaluation conducted at a mining operation in Yunnan Province utilized the Wet Bulb Globe Temperature (WBGT) index as the assessment criterion. Results demonstrate that the enhanced microclimatic circulation system exhibits superior cooling retention capabilities, with a 19.83% increase in refrigeration power and merely 3% cooling capacity dissipation at a 7 m distance, compared to 19.23% in the conventional system. Thermal field analysis confirms that the improved configuration successfully establishes a stable microclimatic circulation zone with significantly more concentrated low-temperature regions. This effectively addresses the principal limitation of conventional systems where conditioned air is readily dispersed by the main ventilation current. The approach presented offers a novel technological pathway for localized thermal environment management in deep mining operations affected by heat stress conditions. Full article

In this study, the cooling performance of fuel cell electric vehicles (FCEVs) with regard to thermal derating is investigated. Particularly in hot climate conditions, low operating temperature of the fuel cell stack and hence low temperature difference to the environment can result in thermal derating of the fuel cell stack. Experimental investigations on a production vehicle with a fuel cell drive (Hyundai Nexo) are conducted to analyze the influence of climatic boundary conditions and a dynamic driving scenario on the thermal management system of the vehicle. Therefore, a new method based on energy balances is introduced to indirectly measure the average cooling air velocity at the cooling module. The results indicate that the two high-power radiator fans effectively maintain a high cooling airflow between a vehicle speed of approximately 30 and 100 $\mathrm{k}\mathrm{m}/\mathrm{h}$, leading to efficient heat rejection at the cooling module largely independent of vehicle speed. Furthermore, this study reveals that the efficiency of the fuel cell system is notably affected by ambient air temperature, attributed to the load on the electric air compressor (EAC) as well as on cooling system components like cooling pump and radiator fans. However, at the stack level, balance of plant (BoP) components demonstrate the ability to ensure ambient temperature-independent performance, likely due to reliable humidification control up to 45 °C. Additionally, a new method for determining thermal derating of FCEVs on roller dynamometer tests is presented. A real-world uphill drive under ambient temperatures exceeding 40 °C demonstrates derating occurring in 6.3% of the time, although a worst case with an aged stack and high payload is not investigated in this study. Finally, a time constant of 50 $\mathrm{s}$ is found to be suitable to correlate the average fuel cell stack power with a coolant temperature at the stack inlet, which gives information on the thermal inertia of the system observed and can be used for future simulation studies. Full article

Daily reference crop evapotranspiration (ET₀) is crucial for precision irrigation management, yet traditional prediction methods struggle to capture its dynamic variations due to the complexity and nonlinearity of meteorological conditions. To address this, we propose an Improved Informer model to enhance ET₀ prediction accuracy, providing a scientific basis for agricultural water management. Using meteorological and soil data from the Yingde region, we employed the Maximal Information Coefficient (MIC) to identify key influencing factors and integrated Residual Cycle Forecasting (RCF), Star Aggregate Redistribute (STAR), and Fully Adaptive Normalization (FAN) techniques into the Informer model. MIC analysis identified total shortwave radiation, sunshine duration, maximum temperature at 2 m, soil temperature at 28–100 cm depth, and surface pressure as optimal features. Under the five-feature scenario (S3), the improved model achieved superior performance compared to Long Short-Term Memory (LSTM) and the original Informer models, with MAE reduced to 0.065 (LSTM: 0.637, Informer: 0.171) and MSE to 0.007 (LSTM: 0.678, Informer: 0.060). The inference time was also reduced by 31%, highlighting the enhanced computational efficiency. The Improved Informer model effectively captures the periodic and nonlinear characteristics of ET₀, offering a novel solution for precision irrigation management with significant practical implications. Full article

Axial flow fans are widely used for heat dissipation in electronic devices. Due to its frequent speed-regulation to adapt to the change in heat load, a fan can cause significant electromagnetic radiation interference. In this study, a peak absorption filtering method is proposed to address the radiation interference issue in a high-speed PWM axial flow fan. The mechanism and coupling paths of radiation interference were analyzed, and a radiation interference calculation using finite integration technique by a hybrid field-circuit model and experimental measurement were conducted to identify the winding as the main source of radiation in PWM fan. Considering the limited space inside the fan, an integrated, non-inductive filtering circuit was designed to absorb the peak voltage entering the windings and the filter parameters are determined via circuit simulation. The measurement results indicate that the filtering method can reduce overall electromagnetic interference with a maximum peak reduction of 41.9 dB, without affecting the useful signals. Full article

To improve the thermal performance of air-cooled panel-type radiators for transformers, a multi-fan horizontal blowing method was designed in this paper, and the thermo-hydraulic performance of the oil-side and air-side of the panel-type radiator was investigated with a simplified numerical method and experiments. The uniform air distribution and zoned heat dissipation ideas were used for three blowing methods, which can increase the proportion of air supply for the high-temperature area of the radiator and apply multiple fans for zoned heat dissipation of the insulating oil in the radiator. Then, the effect of different insulating oil flow rates on the heat dissipation performance of the panel-type radiator was investigated. It was shown that the computational time for the simplified numerical simulation method used for an air-cooled panel-type radiator could be effectively shortened with a small relative error. Due to a more uniform air supply and prioritized air distribution for the high-temperature areas using the multi-fan horizontal blowing method, the overall heat dissipation efficiency was improved. Among the three blowing methods, the best heat dissipation performance was obtained by using the six-fan horizontal blowing scheme, which can improve the performance by about 10.42% and 15.44% in experimental and numerical studies, respectively, as compared with the traditional blowing method. Full article

Light curve analysis of defunct satellites is critical for characterizing their rotational motion. An accurate understanding of this aspect will benefit active debris removal and on-orbit servicing missions as part of the solution to the space debris issue. In this study, we explored the attitude behavior of inactive GLONASS satellites, specifically a repeating pattern observed in their spin period evolution. We utilized a large amount of data available in the light curve database maintained by the Astronomical Institute of the University of Bern (AIUB). The morphology of the inactive GLONASS light curves typically features four peaks in two pairs and is presumably attributed to the presence of four evenly distributed thermal control flaps or radiators on the satellite bus. The analysis of the periods extracted from the light curves shows that nearly all of the inactive GLONASS satellites are rotating and exhibit a periodic oscillating pattern in their spin period evolution with an increasing or decreasing secular trend. Through modeling and simulation, we found that the periodic pattern is likely a result of canted solar panels that provide an asymmetry in the satellite model and enable a wind wheel or fan-like mechanism to operate. The secular trend is a consequence of differing values of the specular reflection coefficients of the front and back sides of the solar panels. Assuming an empirical model describing the spin period evolution of 18 selected objects, we found significant variations in the average spin period and amplitude of the oscillations, which range from 8.11 s to 469.58 s and 1.10 s to 513.24 s, respectively. However, the average oscillation period remains relatively constant at around 1 year. Notably, the average spin period correlates well with the average amplitude. The empirical model can be used to extrapolate the spin period in the future, assuming that the oscillating pattern is preserved and roughly shows a linear trend. Full article

Sound-based early fault detection for vehicles is a critical yet underexplored area, particularly within Intelligent Transportation Systems (ITSs) for smart cities. Despite the clear necessity for sound-based diagnostic systems, the scarcity of specialized publicly available datasets presents a major challenge. This study addresses this gap by contributing in multiple dimensions. Firstly, it emphasizes the significance of sound-based diagnostics for real-time detection of faults through analyzing sounds directly generated by vehicles, such as engine or brake noises, and the classification of external emergency sounds, like sirens, relevant to vehicle safety. Secondly, this paper introduces a novel dataset encompassing vehicle fault sounds, emergency sirens, and environmental noises specifically curated to address the absence of such specialized datasets. A comprehensive framework is proposed, combining audio preprocessing, feature extraction (via Mel Spectrograms, MFCCs, and Chromatograms), and classification using 11 models. Evaluations using both compact (52 features) and expanded (126 features) representations show that several classes (e.g., Engine Misfire, Fuel Pump Cartridge Fault, Radiator Fan Failure) achieve near-perfect accuracy, though acoustically similar classes like Universal Joint Failure, Knocking, and Pre-ignition Problem remain challenging. Logistic Regression yielded the highest accuracy of 86.5% for the vehicle fault dataset (DB1) using compact features, while neural networks performed best for datasets DB2 and DB3, achieving 88.4% and 85.5%, respectively. In the second scenario, a Bayesian-Optimized Weighted Soft Voting with Feature Selection (BOWSVFS) approach is proposed, significantly enhancing accuracy to 91.04% for DB1, 88.85% for DB2, and 86.85% for DB3. These results highlight the effectiveness of the proposed methods in addressing key ITS limitations and enhancing accessibility for individuals with disabilities through auditory-based vehicle diagnostics and emergency recognition systems. Full article

Axial flow fans, used for heat dissipation in electronic equipment, may generate significant electromagnetic interference during PWM speed regulation. Due to its multiple radiation sources and relatively smaller size compared to the equipment, the radiation prediction model for equipment-level EMC analysis often involves a huge number of grids, which leads to computational difficulties and inefficiencies, and thus an equivalent modeling method for the electromagnetic radiation of PWM fan is presented. First, a detailed field-circuit coupling model of the radiation from winding and driving circuits is established using the time-domain finite-integral method with non-uniform grids. Then, a near-field hexahedron is defined to surround the fan, and the electromagnetic field of all its surfaces is derived based on the Huygens principle and calculated. Finally, the hexahedron encapsulating all radiation sources within the fan can be used in a higher level simulation as replicable and reusable equivalent sources. The proposed method is validated by a numerical example and actual measurements and applied to predict the radiation emissions within an electronic enclosure. The results show that the equivalent model can reduce 81.4% computation time and maintain good consistency in comparison to the detailed field-circuit coupling model. Full article

The cooling system plays an essential role in regulating the temperature of hybrid vehicle engines. With the contemporary surge in the number of hybrid vehicles, the cooling system’s performance is vital for the safe and stable operation of these cars. The radiator, as the core component of the cooling system, has become central to enhancing thermal efficiency through performance optimization. Improvements to existing radiators are especially important in order to meet increasing performance demands. This paper firstly outlines the development of radiator technology for hybrid vehicles both domestically and internationally; it then analyzes the tube and belt radiator, and selects a louvered finned radiator with highly efficient heat dissipation performance as the object of research. It then carries out the detailed design and assessment of the radiator, formulates an accurate design scheme, and creates a three-dimensional model of the radiator and its main parts using the CATIA V5 software. Finally, the simulation and analysis Fluent software (ANSYS 2023 R1) is used to carry out a comparative analysis of the designed radiator and its important parts. The study focuses on how fin angle, inlet and outlet positioning, radiator orientation, and fan speed affect thermal performance. The findings indicate that a 26° fin angle, a same-side inlet and outlet layout, correct radiator orientation, and higher fan speeds enhance cooling efficiency. These optimizations improve radiator performance, ensuring efficient cooling under various operating conditions. Full article

The paper deals with the research on the influence of the shapes of tubes and fins of automobile engine radiators and ethylene glycol coolants of type G12 on the cooling process. This involves cross-flow without mixing of coolant and air. The circular tubes with straight fins are compared with flat tubes with corrugated fins at identical external dimensions of the radiators. The new coolant is compared with the used coolant (10 years of usage) and further with a mixture of the used coolant and the additive (coolant enhancer). The goal is to reduce the heat dissipation time during the cooling process. Forced air convection is generated by three fan variants with diameters ϕ400 mm, ϕ345 mm, and a pair of fans ϕ345 mm and ϕ290 mm. The radiator core with flattened tubes and corrugated fins achieved lower outlet temperatures of 0.35 °C, 1.56 °C, and 2.43 °C compared to circular tubes and straight fins when using the ϕ400 mm diameter fan, the fan pair, and the ϕ345 mm diameter fan, respectively. The addition of the coolant enhancer to the used and new G12 coolant, depending on the fan variant, caused the outlet temperature to decrease in the range of 0.64 °C to 1.47 °C and 0.55 °C to 1.65 °C, respectively. The fan cover is also important for efficient cooling. Refilling of the coolant enhancer in the used coolant ensured that the heat transfer properties were recovered. Full article

This review presents a comprehensive examination of recent advancements and findings related to return-temperature reduction in District Heating (DH) systems, with a focus on enhancing overall system efficiency at end-user sites. The review categorizes and clarifies various return-temperature reduction techniques, emphasizing aspects such as building energy performance, heat emitters, thermostatic radiator valves, and substation units. One shall note that return temperature is not a parameter that can be directly controlled within a DH system; instead, it is influenced indirectly by adjusting various system parameters throughout the design, commissioning, operation, and control phases. Key insights include the direct impact of heat demand on return temperatures; the pivotal role of indoor heating systems in optimizing thermal energy use in relation to heat demand; the significance of thermostatic radiator valves in regulating heat output and maintaining low return temperatures; the advantages of ventilation radiators and add-on fans in enhancing radiator efficiency; the necessity for effective substation operation to improve system cooling capacity; and the critical role of operational control strategies in achieving optimal system performance. These findings underscore the need for integrated approaches in DH system design and operation to achieve lower return temperatures and improve overall system efficiency. Full article

The temperature inside broiler houses is crucial to broiler health, welfare, and productivity. High stocking density in broiler houses can easily lead to nonuniform temperature conditions, which would cause broilers to suffer cold and heat stress. It is essential to assess the temperature distribution inside broiler houses and investigate the factors that affect temperature uniformity. Therefore, in this study, temperature, wind velocity, and differential pressure were monitored in the aisle, at the sidewall inlet, and outside the sidewalls of a commercial stacked-deck cage broiler house in Northeast China aiming to continuously monitor the temperature throughout the entire fattening period. Results show that the maximum temperature difference increased from 1.85 °C to 6.43 °C, while the daily fluctuation increased from 2.27 °C to 5.80 °C. The highest temperature was consistently recorded at the side of the exhaust fans (p < 0.001) in the longitudinal direction. In the lateral direction, the temperature difference varies periodically with solar radiation. The average temperature at the southern location (23.58 ± 1.97 °C), which faces the sun, was higher than that at the northern location (23.35 ± 1.38 °C), which is in the shade, during periods of solar radiation (p < 0.001) at the last testing period. However, without solar radiation, the northern location recorded a warmer temperature (23.19 ± 1.41 °C) compared to the southern location (22.30 ± 1.67 °C) (p < 0.001). The lateral temperature differences are strongly positively correlated with solar radiation and wind speed (p < 0.001). In conclusion, the inside temperature nonuniformity and fluctuation increased as the broiler age increased, which affected the production performance of broilers. Nonuniform solar radiation and wind speed can lead to differences in the inlet temperature and air volume between both sidewalls, thereby affecting the uniformity of the lateral temperature inside the house. Full article