Extreme Angles Research Articles

LittleFaceNet: A Small-Sized Face Recognition Method Based on RetinaFace and AdaFace.

For surveillance video management in university laboratories, issues such as occlusion and low-resolution face capture often arise. Traditional face recognition algorithms are typically static and rely heavily on clear images, resulting in inaccurate recognition for low-resolution, small-sized faces. To address the challenges of occlusion and low-resolution person identification, this paper proposes a new face recognition framework by reconstructing Retinaface-Resnet and combining it with Quality-Adaptive Margin (adaface). Currently, although there are many target detection algorithms, they all require a large amount of data for training. However, datasets for low-resolution face detection are scarce, leading to poor detection performance of the models. This paper aims to solve Retinaface's weak face recognition capability in low-resolution scenarios and its potential inaccuracies in face bounding box localization when faces are at extreme angles or partially occluded. To this end, Spatial Depth-wise Separable Convolutions are introduced. Retinaface-Resnet is designed for face detection and localization, while adaface is employed to address low-resolution face recognition by using feature norm approximation to estimate image quality and applying an adaptive margin function. Additionally, a multi-object tracking algorithm is used to solve the problem of moving occlusion. Experimental results demonstrate significant improvements, achieving an accuracy of 96.12% on the WiderFace dataset and a recognition accuracy of 84.36% in practical laboratory applications.

Broadband Linear to circular polarization conversion over extreme angle of view using a single layer Frequency selective surface

Broadband Linear to circular polarization conversion over extreme angle of view using a single layer Frequency selective surface

Breaking the angular dispersion limit in thin film optics by ultra-strong light-matter coupling

Thin film interference is integral to modern photonics, e.g., allowing for precise design of high performance optical filters, photovoltaics and light-emitting devices. However, interference inevitably leads to a generally undesired change of spectral characteristics with angle. Here, we introduce a strategy to overcome this fundamental limit in optics by utilizing and tuning the exciton-polariton modes arising in ultra-strongly coupled microcavities. We demonstrate optical filters with narrow pass bands that shift by less than their half width (< 15 nm) even at extreme angles. By expanding this strategy to strong coupling with the photonic sidebands of dielectric multilayer stacks, we also obtain filters with high extinction ratios and up to 98% peak transmission. Finally, we apply this approach in flexible filters, organic photodiodes, and polarization-sensitive filtering. These results illustrate how strong coupling provides additional degrees of freedom in thin film optics that will enable exciting new applications in micro-optics, sensing, and biophotonics.

Does Tibial Plateau Slope and Depth Influence ACL Strain In Vivo?

The anterior cruciate ligament (ACL) is loaded under tension when the tibia translates anteriorly relative to the femur. The shape of the articular surfaces of the tibiofemoral joint may influence the amount of anterior tibial translation under compressive loading. Thus, a steep lateral tibial plateau and a shallow medial plateau are thought to be risk factors for ACL injury. The purpose of this study was to evaluate whether tibial plateau slope and depth influence peak ACL strain during a single-leg jump. We hypothesized that there would be a significant correlation between tibial plateau slope and depth with ACL strain. Descriptive laboratory study. A total of 17 healthy participants (8 male, 9 female) were assessed using magnetic resonance imaging (MRI) and high-speed biplanar radiography to obtain peak ACL strain during a single-leg jump. Two orthopaedic surgeons used the sagittal plane MRI scans to measure the medial and lateral tibial plateau slopes and the medial tibial plateau depth. The intraclass correlation coefficient was used to assess measurement reliability, and the Spearman rank correlation was used to evaluate the relationship between measurements of tibial morphology and peak ACL strain during the single-leg jump. The overall range of intraclass correlation coefficients for intra- and interrater reliability of the medial and lateral tibial plateau slopes and medial plateau depth was 0.59 to 0.97. No significant correlations were found between peak ACL strain and any of the slope or depth measurements. In this cohort of healthy participants, correlations between any of the tibial plateau measurements with peak ACL strain during a single-leg jump were not detected. These findings are consistent with prior work, suggesting that tibial plateau slope and depth may not be linked to risk for ACL rupture. However, it is possible that tibial plateau morphology may interact with other factors to increase ACL injury risk or that individuals with extreme slope angles may produce differing results. This study enhances the knowledge of the loading mechanisms for the ACL and thus improves the understanding of risk factors for ACL injury.

Efficient wide-angle broadband blazed gratings enabled by metasurfaces

Metasurfaces composed of two-dimensional nanopillar arrays can manipulate light fields in desirable ways and exhibit the unique advantage of beam steering. Here, we experimentally demonstrate a metasurface-based wide-angle broadband all-dielectric blazed grating with an extreme incident angle of up to 80°, which is achieved by optimizing the wide-angle phase shifts and transmissivities of the unit cells. It exhibits a maximum diffraction efficiency of 72% and a high average efficiency of 64% over a wide range of incident angles from −80° to 45° at 1.55 μm. Moreover, the proposed grating has a broad bandwidth of 200 nm (1.45–1.65 μm), and average efficiencies of more than 50% can be achieved experimentally over the same incidence angles. Our results may pave the way for the creation of novel and efficient flat optical devices for wavefront control.

Neurosurgical applications of the exoscope: from in vitro studies to real-life surgical use in selective dorsal rhizotomy

BackgroundThe microscope has been the gold standard in neurosurgical practice due to its ability to magnify anatomical structures. However, it has limitations, including restricted visual fields and ergonomic challenges that can lead to surgeon fatigue and musculoskeletal issues. The exoscope is an emerging technology that may address these limitations by offering comparable magnification with improved ergonomics. MethodsThis study compares the traditional microscope (KINEVO 900) with a 3D digital exoscope (Aeos Digital Microscope) in visual field width, image sharpness, and ergonomic impact. Visual field assessments were conducted using millimeter paper at a fixed distance, while image sharpness was evaluated using graph paper with pins at different depths. Ergonomic evaluation involved simulating surgical positions using a spine anatomical model. The practical applicability was tested during Selective Dorsal Rhizotomy (SDR) procedures, comparing the surgeon's experience with both devices over 20 consecutive cases. ResultsThe exoscope provided a larger visual field (81.18 cm2) compared to the microscope's (54.10 cm2). Image sharpness was similar for both devices across various depths and zoom levels. Ergonomically, the exoscope allowed the surgeon to maintain a neutral posture while visualizing extreme angles, unlike the microscope, which required significant upper body movement. In SDR procedures, the exoscope improved surgeon comfort and interaction with the operating team, despite an initial learning curve. ConclusionsThe exoscope presents notable advantages in terms of visual field and ergonomics. The exoscope’s ability to facilitate better posture and team communication without compromising image quality makes it an addition to neurosurgical practice, as in SDR.

Syndesmotic Screw Angle in Lateral Fibular Pre-Contoured Plates Impacts Quality of Syndesmotic Reduction: A Cadaveric Study

Category: Ankle; Trauma Introduction/Purpose: Achieving adequate reduction of ankle syndesmosis after syndesmotic injury is critical as malreduction can lead to accelerated arthritis, pain, and instability. Static fixation with syndesmotic screw is the gold standard where 1-2 syndesmosis screws are placed obliquely at a 25-30° angle from posterolateral to anteromedial, parallel to the joint line. While retrospective studies have been conducted on screw level and extreme angle changes, it is unclear how changes in screw angle impacts rates of malreduction. We sought to assess the effect of syndesmotic screw angle within lateral fibular pre-contoured plates on the quality of syndesmotic reduction. We hypothesize that greater deviations from the 30° screw angle would cause malreduction of the syndesmosis, particularly as the screw head engaged with the pre-contoured plate at sharper angles. Methods: Twelve cadaveric legs were used for this study. All legs were CT scanned pre- and post-simulated syndesmosis injury, with the uninjured serving as the controls. Six pairs of legs were split into 3 groups of 4, (20, 30, and 40 degree screw angles). Each specimen was confirmed to have no prior syndesmosis injury prior to conducting the simulated syndesmosis injury. Syndesmotic screw angle was determined by 3D-printed custom drill guides with drilling performed by a fellowship-trained trauma surgeon, tricortical screws were placed and scanned, then repeated with quad-cortical screws. Syndesmosis reduction was assessed via pre- and post-injury CT scans, we compared the following measures at 1 cm above the tibial plafond: anterior and posterior tibiofibular distance, anteroposterior fibular translation, and fibular rotation. Malreduction was defined as any significant deviation of the 4 measurements compared to pre-injury. Pre-injury K-wire tracks served as additional verification of translation or rotation. Results: In total, 24 reductions were measured and analyzed for malreduction. Measurements, grouped by screw angle, of post injury CT scan at 1 cm above the tibial plafond showed malreductions as follows: 3 of 8 at 20°, 0 of 8 at 30°, and 6 of 8 at 40°. Fischer’s exact demonstrated a significant change between angle and presence of malreduction (p = 0.009). Syndesmotic screw angle significantly impacted change in anteroposterior fibular translation with positive changes indicating posterior translation and negative, anterior translation (20°: 0.98 mm, 30°: 0.068 mm, 40°: -1.91 mm, p= 0.0094). Syndesmotic screw angle did not impact change in anterior or posterior tibiofibular distance or fibula angle. Malreduction did not differ between tri and quad cortical screws (p = 0.5). Conclusion: Our study shows evidence that deviation of syndesmotic screw angle within a pre-contoured lateral fibula plate significantly impacts malreduction rates and anteroposterior fibular translation regardless of tri- or quad-cortical fixation. While our study does not support our hypothesis that plate-screw interaction is responsible for malreduction in syndesmosis fixation, it does support that the ideal syndesmotic screw angle is approximately 30 degrees and that deviation from this angle risks anteroposterior fibular translation and malreduction.

Numerical Investigations of Deckhouse Height to the Self-Righting Moment of the Patrol Boat

The design of patrol boats, especially in Indonesian waters with extreme sea conditions, requires good stability capabilities and self-righting moments. These conditions require patrol boats to have anti-capsized capabilities where, with these capabilities, the patrol boat can return to an upright position at extreme heeling angles. This study investigates how changing the center of gravity (CoG) due to the deckhouse height factor improves self-righting moment capabilities. Four different deckhouse heights are examined to find the optimal self-righting roll moment, with a deckhouse height in the 2.01–2.31 m range. In addition, the presence of the self-righting roll moment is also validated by the computational fluid dynamics (CFD) method using three different mesh sizes. The height of the deckhouse can significantly influence the ship’s stability. The initial investigation shows ships with minimum deckhouse heights of 2.06 m have positive righting lever arms at 170° and are classified as anti-capsized ships. It has been discovered that buoyancy and the center of gravity are crucial variables in obtaining the self-righting moment. The deckhouse’s height increases the stability of the ship’s righting arm by enhancing the metacenter point. The findings demonstrate that more excellent stability is achieved with a larger deckhouse height.

A Robust and Efficient Method for Effective Facial Keypoint Detection

Facial keypoint detection technology faces significant challenges under conditions such as occlusion, extreme angles, and other demanding environments. Previous research has largely relied on deep learning regression methods using the face’s overall global template. However, these methods lack robustness in difficult conditions, leading to instability in detecting facial keypoints. To address this challenge, we propose a joint optimization approach that combines regression with heatmaps, emphasizing the importance of local apparent features. Furthermore, to mitigate the reduced learning capacity resulting from model pruning, we integrate external supervision signals through knowledge distillation into our method. This strategy fosters the development of efficient, effective, and lightweight facial keypoint detection technology. Experimental results on the CelebA, 300W, and AFLW datasets demonstrate that our proposed method significantly improves the robustness of facial keypoint detection.

Experiment investigation on secondary flow loss and flow control mechanisms in a variable compressor cascade with penny cavities

Variable Stator Vanes (VSVs) with penny cavities are an important method to improve the efficiency of compressors. However, the annular and radial gaps in VSVs introduce complex flow structures, posing challenges in enhancing compressor efficiency. This article employs low-speed wind tunnel experiments to study the impact mechanisms of VSVs' adjustment angle and radial gap size on secondary flow losses and implements single-hole suction as a means of flow control to reduce total pressure loss. The results indicate that radial gap leakage has a certain inhibitory effect on annular gap leakage at general adjustment angles. Total pressure loss decreases initially as the radial gap increases but once the radial gap further enlarges and dominates the loss components, the total pressure loss increases proportionally with the radial gap. At extreme adjustment angles, where the lateral pressure gradient is significant, radial gap leakage intensity is high and comprises the major part of the loss, leading to an increase in total pressure loss in proportion to radial gap enlargement. Additionally, single-hole suction is effective under various conditions, with the potential to reduce total pressure loss by up to 19.4 %. These findings provide guidance for the application of VSVs in further improving compressor efficiency.

Structural optimization design of multi ribbed composite wall of building components under seismic load based on random optimization algorithm and resilience model

The multi ribbed composite wall structure is also known as the multi ribbed wall panel light frame structure. This structure is suitable for housing construction in the residential field. The special structural failure process and mode of multi ribbed composite walls are different from traditional walls. To fully utilize the excellent structural performance in building construction and improve the seismic performance of the building, based on the transformation principle of subset optimization algorithm for optimization problems, a constrained subset simulation optimization algorithm suitable for optimizing the maximum displacement angle of multi ribbed composite wall panels is designed. The Bayesian algorithm is used to construct a restoring force model for multi ribbed composite wall panels. The constrained subset simulation optimization algorithm and resilience model are used to optimize the seismic performance of 4-layer multi ribbed composite wall panels. The results show that the section height and the equivalent slant support width of the continuous column for the 4-story multi ribbed composite wall panel change from discrete distribution to aggregation with the increase of iteration. Finally, the sampling is stable in the 9th floor. At this time, the section height of the continuous column is 230 mm, and the equivalent slant support width is 525. After optimization, the failure probability of both extreme displacement angle states has decreased. When the peak ground acceleration is 1.0 g, the optimized second limit state failure probability is less than 100%. When the peak ground acceleration value is between 0.2 g and 0.6 g, both limit states show a rapid upward trend. The constrained subset simulation optimization algorithm and Bayesian quantitative resilience model proposed in the research can effectively optimize the seismic performance of multi ribbed composite walls.

Wind farm modelling of tilted rotors

This study explores the benefits of tilted rotors in wind farms, focusing on a 3x3 grid of 10MW turbines and a 153-turbine farm modelled after the Hollandse-Kust West site with 15MW turbines. Computational Fluid Dynamics models ranging from mid to higher order, including FarmFlow (Parabolic RANS), TNO-VBM (RANS), and NREL-SOWFA (LES), were validated against CL-Windcon wind tunnel measurements.Comparisons between low and high-order CFD models reveal good agreement, with LES indicating increased wake mixing. Tilted rotor simulations align well, except for the lower-order model, deviating at extreme tilt angles. Positive tilts in a 3x3 farm result in a 10% increase in sub-rated wind farm yield and a 26% reduction in peak thrust loads during post-rated conditions. However, for larger wind farm clusters, tilting the rotors can increase the production of some parts within while its overall production is not increased. The investigated results depend on the tested scenario, thus further exploration is recommended.

Numerical Simulation and Experimental Study on the Aerodynamics of Propulsive Wing for a Novel Electric Vertical Take-Off and Landing Aircraft

The electric vertical take-off and landing (eVTOL) aircraft offers the advantages of vertical take-off and landing, environmental cleanliness, and automated control, making it a crucial component of future urban air traffic. As competition intensifies, demands for aircraft performance are escalating, including forward flight speed and payload capacity. The article presents a novel eVTOL design with propulsive wings and establishes methodologies for propulsive wing unsteady numerical simulation and wind tunnel experiments, analyzing its aerodynamic characteristics and lift enhancement mechanism. The results indicate that the cross-flow fan (CFF) provides unique airflow control capabilities, enabling the propulsive wing to achieve remarkably high lift coefficients (exceeding 7.6 in experiments) and propulsion coefficients (exceeding 7.1 in experiments) at extreme angles of attack (30°~40°) and low airspeeds. On the one hand, the CFF effectively controls boundary layer flow, delaying airflow separation at high angles of attack; on the other hand, the rotation of the CFF induces two eccentric vortices, generating vortex-induced lift and propulsion. The aerodynamic performance of the propulsive wing depends on the advance ratio and angle of attack. Typically, both lift and propulsion coefficients increase with the advance ratio, while lift and drag coefficients increase with the angle of attack. The propulsive wing shows significant advantages and prospects for eVTOL aircrafts in the low flight velocity range (0–30 m/s).

Posterior Cranial Fossa Surgery with a 3 Dimensional Exoscope: A Single-Center Survey-Based Analysis and a Literature Review

The potential advantages of exoscopy have been discussed theoretically for a long time. Such a concept holds significance, especially in the specific setting of the posterior cranial fossa (PCF), characterized by complex anatomy and long and narrow surgical corridors with relatively extreme working angles. We aimed to: 1) analyze the institutional preliminary case-based data on the use of the Robotic 3D Exoscope AEOS Aesculap in three different PCF approaches: retrosigmoid (RSA), midline suboccipital (MSA), and supracerebellar infratentorial via feedbacks was collected using a 20-point questionnaire, and 2) perform a comprehensive review of the literature concerning the use of EX in PCF surgery. A total of 38 patients with neurosurgical pathologies underwent a neurosurgical procedure using the EX (Robotic 3D exoscope AEOS Aesculap) at our institution between January and March 2022. 21 surgeons were involved in the abovementioned PCF surgeries and answered the questionnaire. The main perceived advantages were in terms of ergonomics (67%), magnification (52%), and visualization of extreme angles. The main reported disadvantage was color vision (16, 76%), followed by manual mobility (24%). Concerning the review, the search of the literature yielded a total of 177 results. Upon full-text review, 17 articles were included, including 153 patients. In conclusion, our study provides a comprehensive evaluation of the advantages and challenges associated with using the exoscope in posterior fossa surgery, setting a precedent as the first to report on a questionnaire-based analysis of exoscope utilization in this specific domain.

Error Analysis of Stonex X300 Laser Scanner Close-range Measurements

This research reports an error analysis of close-range measurements from a Stonex X300 laser scanner in order to address range uncertainty behavior based on indoor experiments under fixed environmental conditions. The analysis includes procedures for estimating the precision and accuracy of the observational errors estimated from the Stonex X300 observations and conducted at intervals of 5 m within a range of 5 to 30 m. The laser 3D point cloud data of the individual scans is analyzed following a roughness analysis prior to the implementation of a Levenberg–Marquardt iterative closest points (LM-ICP) registration. This leads to identifying the level of roughness that was encountered due to the range-finder’s limitations in close-ranging as well as measurements that were obtained from extreme incident angle signals. The measurements were processed using a statistical outlier removal (SOR) filter to reduce the noise impact toward a smoother data set. The geometric differences and the RMSE values in the 3D coordinate directions were computed and analyzed, which showed the potential of the Stonex X300 measurements in close-ranging following a careful statistical analysis. It was found that the error differences in the vertical direction had a consistent behavior when the range increased, whereas the errors in the horizontal direction varied. However, it is more common to produce errors in the vertical direction as compared to the horizontal one.

Association between musculoskeletal pain and exposures to awkward postures during work: a compositional analysis approach.

This study aimed to explore the association between arm elevation and neck/shoulder pain, and trunk forwarding bending and low back pain among home care workers. Home care workers (N = 116) from 11 home care units in Trondheim, Norway, filled in pain assessment and working hours questionnaire, and wore 3 accelerometers for up to 7 consecutive days. Work time was partitioned into upright awkward posture, nonawkward posture, and nonupright time, i.e. sitting. Within a compositional approach framework, posture time compositions were expressed in terms of log-ratio coordinates for statistical analysis and modeling. Poisson generalized linear mixed models were used to analyze the relationship between arm elevation in upright postures and neck/shoulder pain, and between trunk forward bending in upright postures and low back pain, respectively. Isotemporal substitution analysis was used to investigate the association of pain assessment with the reallocation of time spent in the different postures. Time spent in awkward postures was modest, especially for the more extreme angles (60° and 90°). Adjusting for age, gender, and body mass index, our study suggested that the compositions of time spent by home care workers in awkward postures were significantly associated with pain assessment (P < 0.01). Isotemporal substitution analysis showed that reallocating 5 min from upright posture with arms elevated below to above 60° and 90° was associated with a 6.8% and 19.9% increase in the neck/shoulder pain score, respectively. Reallocating 5 min from a forward bending posture while upright below to above 30°, 60°, and 90° was associated with 1.8%, 3.5%, and 4.0% increase in low back pain, respectively. Although the exposure to awkward postures was modest, our results showed an association between increased time spent in awkward postures and an increase in neck/shoulder pain and low back pain in home care workers. As musculoskeletal pain is the leading cause of sickness absence, these findings suggest that home care units could benefit from re-organizing work to avoid excessive arm elevation and trunk forward bending in workers.

Premonition-driven deep learning model for short-term ship violent roll motion prediction based on the hull attitude premonition mechanism

Ship transit forecasting can provide advanced movement information to a multidimensional wave motion compensation system. However, traditional deep learning models based on data-driven or physical data have difficulty in accurately predicting the rapid variations in ship motion attitudes that frequently occur in complex ocean environments. Therefore, a premonition-driven deep learning model is proposed in this paper to significantly improve the prediction accuracy of ship violent roll motion. This model applies precursor information to predict premonitory values of ship prospective motion attitudes based on an integrated statistical regression model and then employs these premonitory values to revise the outputs of the deep learning time series model. First, a hull attitude premonition mechanism is presented based on biological premonition cognitive behaviour, which captures the correlation relationships between extreme values by downgrading the globally continuous time series prediction problem to a time-independent regression problem. The corresponding methods for predicting local extreme values and deep feedforward neural network cluster are established based on these correlation relationships between the extreme values to achieve precise premonitory values. Second, the time and amplitude variables of the extreme angle values are transformed to countdown time variables and sequential sets of premonitory angle values. Two types of premonition units and their respective premonitory long short-term memory neural networks are constructed to upgrade the regression problem to a globally continuous time series prediction problem. Finally, a single-step output recurrent strategy is applied to forecast the short-term ship motion attitude for fifteen seconds by considering eleven initially predicted points across the two datasets. In sixty-six simulation experiments, the mean absolute error, root mean squared error, and mean absolute percentage error of the premonition-driven long short-term memory neural networks are considerably lower than those of traditional deep learning models. These simulation experiments verify that the premonition-driven deep learning model can effectively forecast short-term violent ship roll motion and provide safeguards for cargo transfer.

Identification of a major QTL and candidate genes analysis for branch angle in rapeseed (Brassica napus L.) using QTL-seq and RNA-seq.

Branching angle is an essential trait in determining the planting density of rapeseed (Brassica napus L.) and hence the yield per unit area. However, the mechanism of branching angle formation in rapeseed is not well understood. In this study, two rapeseed germplasm with extreme branching angles were used to construct an F2 segregating population; then bulked segregant analysis sequencing (BSA-seq) and quantitative trait loci (QTL) mapping were utilized to localize branching anglerelated loci and combined with transcriptome sequencing (RNA-seq) and quantitative real-time PCR (qPCR) for candidate gene mining. A branching angle-associated quantitative trait loci (QTL) was mapped on chromosome C3 (C3: 1.54-2.65 Mb) by combining BSA-seq as well as traditional QTL mapping. A total of 54 genes had SNP/Indel variants within the QTL interval were identified. Further, RNA-seq of the two parents revealed that 12 of the 54 genes were differentially expressed between the two parents. Finally, we further validated the differentially expressed genes using qPCR and found that six of them presented consistent differential expression in all small branching angle samples and large branching angles, and thus were considered as candidate genes related to branching angles in rapeseed. Our results introduce new candidate genes for the regulation of branching angle formation in rapeseed, and provide an important reference for the subsequent exploration of its formation mechanism.

Anti-reflection metasurface synergizing plasma and lattice modes: an efficient route to wideband electromagnetic transparency under extreme angles

All-angle wideband electromagnetic (EM) transparency for dual polarizations is desired for many practical applications. Conventionally, surface-mount anti-reflection materials or films are usually used to reduce the reflection and thus enhance transparency. In this paper, we propose to achieve wideband EM transparency under extreme angles for both TE- and TM-polarizations using embedded anti-reflection metasurface. The metasurface is composed of a pair of long and short metallic strips, which can introduce both plasma and lattice modes into the original half-wave wall. The plasma mode can create an angle-stable transmission peak at a lower frequency while the lattice mode renders a transmission peak under extreme angles at a higher frequency due to scattering cancellation between short strips and the substrate. By synergizing the plasma, half-wave, and lattice modes consecutively, wide-band transparency can be achieved under extreme angles for TE polarization. Due to the anisotropy of the metasurface, wideband transparency under TM-polarization is maintained. This finally enables us to obtain wideband EM transparency for dual polarizations under extreme angles. More importantly, the metasurface can also be customized to operate best under any given incident angle. Prototypes were designed, fabricated, and measured. Both the simulation and experiment results verify our method. This work provides an efficient route to wideband EM transparency under extreme angles and may find wide applications in communication, radar, and others.

Thermal Management and Electrical Efficiency for Concentrator Photovoltaic Systems Using Multiple Phase Change Materials

The performance of solar panels in generating electrical energy is closely tied to the effectiveness of the employed cooling system. While the utilization of phase change materials (PCMs) as latent thermal units as a cooling system has been suggested for recovering solar panels’ heat, research focusing on a comprehensive comparison of various PCMs for this purpose has been lacking. To address this gap, our study aims to provide a thorough comparative analysis of three distinct PCMs: Gallium, Paraffin RT35HC and CaCl2.6H2O. The objective is to determine the most efficient PCM for cooling solar panels. Using Fluent-Ansys-based numerical simulations, our study investigates the transient (unsteady) thermal exchange between PCMs and a solar panel. The research examines various PCM types housed in a container behind the solar panel, while also assessing the impact of inclination angles (0° to 90°) on thermal and electrical efficiency. Our results highlight Gallium's superior cooling performance and sustained high electrical efficiency. Conversely, CaCl2.6H2O leads to decreased electrical efficiency (less cooling performance), while RT35HC shows potential at extreme angles with a slight efficiency decline (∼10.2%). By offering a comprehensive comparative assessment of diverse PCMs and considering the influence of inclination angles, our study contributes valuable insights to optimizing solar panel cooling systems and enhancing overall energy generation efficiency.