Wide Range Of Incidence Research Articles

Aerodynamic Performance Prediction for Wide-Incidence Turbines Using Graph Neural Network Models Driven by Small-Scale Experimental Data

Abstract To rapidly and accurately predict turbine rotor blade losses within a wide range of incidences (−50–30 deg), graph neural networks (GNNs) are utilized to predict the aerodynamic parameters of two-dimensional turbine blades based on a small-scale experimental dataset. By comparing the backpropagation neural network (BPnn) model and computational fluid dynamics (CFD) results, it is demonstrated that GNNs with appropriately designed graph structures can accurately and quickly predict high-fidelity aerodynamic parameters based on limited experimental data. Unlike traditional data-driven modeling approaches, two innovative methods for improving blade profiles into graph structures are proposed. Relatively few input features are used to comprehensively and effectively represent the turbine blade profile by applying blade profile features in the GNN. The research findings indicate that due to the graph structure, which divides the turbine blade profile into five nodes based on five key points, coupled with high-fidelity experimental data and the unique weight updating mechanism of the graph attention network (GAT) model, the GAT-5 model exhibits the best performance among the studied models. Additionally, when assessing unknown validation blade profiles, the GAT-5 model maintains an absolute error below 6% at an incidence angle of 30 deg compared to the experimental results.

Multifunctional Intelligent Reconfigurable Metasurface.

The emergent reconfigurable metasurfaces (RMs) have attracted a lot of attention due to their potential in broad applications. As a general platform, RMs are able to control the reflection (or refraction) of incident waves with predefined functionalities. Nevertheless, the operation of RMs is highly dependent on the arrival direction of incidence. The self-adaptive design of an RM, so that it can respond to varied incident waves automatically, is highly requested in practical implementation, which is actually challenging. This study reports the realization of an intelligent RM (IRM) system, which can detect the arrival direction of impinging waves and respond to the incidence with a predefined functionality accordingly. This IRM system is constructed by integrating a direction of the arrival estimation module, a frontend by the varactor-based metasurface, and a central control unit. In experiments, an IRM system designed for TM polarization is demonstrated to perform various functions, i.e., retroreflection, directional reflection, and fixed-point energy focusing, which are highly requested by edge communication and sensing. The measured results imply that this IRM system responds quite well within a wide incident range from -60° to 60° in a frequency range from 9 to 9.5 GHz. The proposed IRM can be a good candidate for boosting 5G communication and Internet of Things applications, including beam shaping/steering, RCS manipulation, object imaging, and sensor recharging.

High-accuracy direction measurement and high-resolution computational spectral reconstruction based on photonic crystal array

Portable and wearable miniaturized spectrometers play a crucial role in various fields. In this paper, we present a method for simultaneously realizing high-accuracy direction measurement and high-resolution computational spectral reconstruction based on the angle sensitivity of conventional photonic crystals (PCs), wherein an optical filter array is composed of multiple one-dimensional PCs. The high-angle sensitivity of PCs results in angle-dependent optical spectra. When these spectra with different angles are used to reconstruct the target spectra in an unknown direction and the interval between adjacent angles is sufficiently small, the accurate direction of the target can be automatically identified. Moreover, the computational spectra still have high resolution over a wide range of incidences. The computational spectra under arbitrary polarizations can also be recognized based on the polarization dependence of the PCs at an oblique incidence. Our research results are significant for engineering a new miniaturized comprehensive computational spectrometer with target-direction perception and omnidirectional spectral reconstruction abilities.

Toward high-lift low-solidity design for incidence tolerant gas turbine blade profile

Gas turbines operating under wide operational conditions require minimizing losses across a wide range of incidences. This study employed a blade profile efficient within a 50° incidence range to assess the effect of solidity on performance across wide incidences. The aim was to evaluate the feasibility of adopting high-lift, low-solidity designs for incidence-tolerant blade profiles. The results showed that solidity has both positive and negative effects on loss across a wide range of incidence angles. Increasing the pitch-to-axis chord ratio (the inverse of solidity) from 0.8 to 1.1 not only reduces the blade count by 37.5 % but also enhances performance at negative incidences, reducing the total pressure loss coefficient by up to 17.5 %. However, at positive incidences, the losses increased significantly as the solidity decreased. To expand the operational range of the low-solidity blade profile at positive incidences, strategic integration of leading-edge refinement and maximum deflection adjustment was applied to precisely control losses. This enabled the low-solidity blade profile to maintain lower loss levels compared to conventional high-solidity profiles up to an incidence of 7°, at which point the losses become comparable. The findings indicate that employing high-lift designs with optimized leading-edge and maximum deflection for incidence-tolerant blade profiles is feasible.

A Comparison of Active Pharmacovigilance Strategies Used to Monitor Adverse Events to Antiviral Agents: A Systematic Review.

The safety of antiviral agents in real-world clinical settings is crucial, as pre-marketing studies often do not capture all adverse events (AE). Active pharmacovigilance strategies are essential for detecting and characterising these AE comprehensively. The aim of this study was to identify and characterise active pharmacovigilance strategies used in real-world clinical settings for patients under systemic antiviral agents, focusing on the frequency of AE and the clinical data sources used. We conducted a systematic review by searching three electronic bibliographic databases targeting observational prospective active pharmacovigilance studies, phase IV clinical trials for post-marketing safety surveillance, and interventional studies assessing active pharmacovigilance strategies, focusing on individuals exposed to systemic antiviral agents. We included 36 primary studies, predominantly using Drug Event Monitoring (DEM), with a minority employing sentinel sites and registries. Human immunodeficiency virus (HIV) was the most common condition, with the majority using DEM. Within the DEM, there was a wide range of incidences of patients experiencing at least one AE, and most of these studies used one or two data sources. Sentinel site studies were less common, with two on hepatitis C virus (HCV) and one on HIV, each relying on one or two data sources. The single study using a registry focusing on HIV therapy reported using just one data source. Patient interviews were the most common data source, followed by medical records and laboratory tests. The quality of the studies was considered 'good' in 18/36, 'fair' in 1/36, and 'poor' in 17/36 studies. DEM was the predominant pharmacovigilance strategy, employing multiple data sources, and appears to increase the likelihood of detecting higher AE incidence. Establishing such a framework would facilitate a more detailed and consistent approach across different studies and settings.

DiffRank: Enhancing efficiency in discontinuous frame rate analysis for urban surveillance systems

Urban public safety management relies heavily on video surveillance systems, which provide crucial visual data for resolving a wide range of incidents and controlling unlawful activities. Traditional methods for target detection predominantly employ a two-stage approach, focusing on precision in identifying objects such as pedestrians and vehicles. These objects, typically sparse in large-scale, lower-quality surveillance footage, induce considerable redundant computation during the initial processing stage. This redundancy constrains real-time detection capabilities and escalates processing costs. Furthermore, transmitting raw images and videos laden with superfluous information to centralized back-end systems significantly burdens network communications and fails to capitalize on the computational resources available at diverse surveillance nodes. This study introduces DiffRank, a novel preprocessing method for fixed-angle video imagery in urban surveillance. The method strategically generates candidate regions during preprocessing, thereby reducing redundant object detection and improving the efficiency of the detection algorithm. Drawing upon change detection principles, a background feature learning approach utilizing shallow features has been developed. This approach prioritizes learning the characteristics of fixed-area backgrounds over direct background identification. As a result, alterations in ROI are efficiently discerned using computationally efficient shallow features, markedly accelerating the generation of proposed Regions of Interest (ROIs) and diminishing the computational demands for subsequent object detection and classification. Comparative analysis on various public and private datasets illustrates that DiffRank, while maintaining high accuracy, substantially outperforms existing baselines in terms of speed, particularly with larger image sizes (e.g., an improvement exceeding 300 % at 1920×1080 resolution). Moreover, the method demonstrates enhanced robustness compared to baseline methods, efficiently disregarding static targets like mannequins in display windows. The advancements in candidate area preprocessing enable a balanced approach between detection accuracy and overall detection speed, making the algorithm highly applicable for real-time on-site analysis in edge computing scenarios and cloud-edge collaborative computing environments.

Haemorrhoidal disease in pregnancy: results from a self-assessment questionnaire administered by means of a social network

BackgroundThe anal symptoms occurring during pregnancy and post-partum, mainly related to Haemorrhoidal Disease (HD), have been reported with in a wide range of incidence in the literature. Although in many cases the course of the disease is mild and self-limiting, sometimes it is severe enough to affect quality of life.MethodsOur study has been conducted through a questionnaire administered via social media with the aim of obtaining epidemiologic data on the incidence of the symptoms of HD in an unselected population of pregnant women. In addition, we looked for the presence of those factors notoriously predisposing or associated to HD (constipation, straining on the toilet, low dietary fibres and fluid intake).ResultsOut of 133 patients 51% reported symptoms of HD during pregnancy, mainly in the second and third trimester. Constipation, straining on the toilet, low dietary fibres and fluid intake were not significantly related to incidence of HD. Only a previous history of HD was correlated to onset of symptoms of HD in pregnancy and reached a statistical significance (odds ratio = 5.2, p < 0.001).ConclusionAlthough with the limitations posed by the nature of our retrospective study via a self-assessment interview, our results suggest that the occurrence of HD in pregnancy seems not sustained by the classical risk factors observed in the general population. At the moment, specific therapeutic measures are lacking and treatment relies on empiric suggestions concerning diet, fluid intake, bowel care, local ointment. Further studies are needed in order to identify a targeted etiologic treatment.

The Current Incidence and Future Projection of Acetabular Fractures in Korea.

As one of the most challenging fractures to orthopedic surgeons, acetabular fractures show a wide range of incidence among countries and regions with even more variance in the treatment modalities. In this study, we aimed to investigate the epidemiology of acetabular fractures, and to compare the rate of subsequent total hip arthroplasty (THA) between nonoperative and operative treatments in South Korea using a medical claims database. This was a retrospective study using the Korean Health Insurance Review and Assessment database. Patients admitted for acetabular fractures from January 2007 to December 2018 were identified using International Classification of Diseases-10 codes. Kaplan-Meier survival analysis was used to compare the cumulative incidence of THA between two groups. We also evaluated the survivorship of operative group according to the type of institutions. The incidence rate of acetabular fractures increased by 28% between 2007 and 2018. Acetabular fractures were more common in men (62%) than women (38%), and most common in the patients older than 80 years. The number of acetabular fractures was estimated to increase 1.7-fold in 2030 compared to 2018. Operative treatment accounted for 16% of cases, and nonoperative treatment for 84%. The incidence of subsequent THA was higher in the operative treatment group than in the nonoperative group (P < 0.001). The higher rate in the operative treatment group is probably related with the severity of the fracture type. The rate of subsequent THA was higher in patients who initially treated in general hospitals compared with those who were initially treated in tertiary hospitals. The incidence of acetabular fractures is increasing in South Korea, in line with global trends. Most acetabular fractures are treated conservatively, and those who receive surgery are more likely to require a subsequent THA. Patients who were operated in general hospitals had highest possibility of subsequent THA after acetabular fractures.

Study on the thermal-mechanical coupling characteristics and influencing parameters of heat pipe radiator under accident conditions

Space reactors, due to their strong environmental adaptability, high power output, small size, and long lifespan, are the most important direction for the development of nuclear energy systems in space. The waste heat of the space reactor system needs to be dissipated through a radiative heat exchanger. The current numerical analysis of the heat exchanger predominantly emphasizes heat transfer phenomena while neglecting the effect of mechanical properties. This study utilizes a self-developed, highly accurate thermal-mechanical coupling calculation program to conduct a numerical analysis of the heat pipe radiator. The main objective is to acquire a comprehensive understanding of its thermal-mechanical coupling characteristics and evaluate the effects of various accident conditions on the radiator. The results indicate that the heat dissipation power obtained from the thermal-mechanical coupled calculation is 0.42% higher than that obtained from the standalone heat transfer calculation. Single axial heat pipe failure leads to a 9.13% decrease in heat dissipation power for the affected module, while two axial heat pipes failure results in a 21.17% decrease. The ability of the heat pipe radiator to meet the heat dissipation power requirements under different failure conditions indicates its capacity to effectively respond to a wide range of incidents, thereby emphasizing its superior safety level.

Perfect absorber with high sensitivity based on hexagonal star graphene surface

Graphene absorbers have attracted wide attention due to their high absorption rate and narrow bandwidth in the terahertz field. In this study, we proposed a dual-band terahertz tunable perfect absorber designed with a hexagonal star ring and a circular ring monolayer graphene metasurface, which exhibits tunable, polarization-insensitive, and high sensitivity characteristics. The graphene absorber was simulated by using the finite element method and validated by using the impedance matching method. Simulation results show that this structure has two perfect absorption peaks at 4.8 and 8.04 THz. The variation of the dielectric layer material was analyzed, and the parameters of the structure and the intrinsic graphene parameters were adjusted to control the absorption efficiency of the dual-band absorption peaks. Simulation results show that the high symmetry of the structure brings incident and polarization-insensitive properties, maintaining absorption higher than 98% over a wide range of incident and azimuth angles. The sensing performance of the device was investigated by varying the ambient refractive index, and the highest sensitivity parameter S of the absorber reached to 2.375 THz/RIU. These results demonstrate that this high-sensitivity sensor has great potential for terahertz imaging and microstructure detection.

Fourier-space generalized magneto-optical ellipsometry

The magneto-optical Kerr effect (MOKE) is widely exploited in laboratory-based setups for the study of thin films and nanostructures, providing magnetic characterization with good spatial and temporal resolutions. Due to the complex coupling of light with a magnetic sample, conventional MOKE magnetometers normally work by selecting a small range of incident wave-vector values, focusing the incident light beam to a small spot, and recording the reflected intensity at that angular range by means of photodetectors. Using this approach, additional methodologies and measurements are required for full vectorial magnetic characterization. Here, we computationally investigate a Fourier-space MOKE setup, where a focused beam ellipsometer using high numerical aperture optics and a camera detector is employed to simultaneously map the intensity distribution for a wide range of incident and reflected wave vectors. We employ circularly incident polarized light and no analyzing optics, in combination with a fitting procedure of the light intensity maps to the analytical expression of the Kerr effect under linear approximation. In this way, we are able to retrieve the three unknown components of the magnetization vector as well as the material' s optical and magneto-optical constants with high accuracy and short acquisition times, with the possibility of single-shot measurements. Fourier MOKE is thus proposed as a powerful method to perform generalized magneto-optical ellipsometry for a wide range of magnetic materials and devices.

The Incidence and the Risk Factors for Pharyngocutaneous Fistula following Primary and Salvage Total Laryngectomy

The pharyngocutaneous fistula (PCF) is the most common complication following a total laryngectomy (TL) with a wide range of incidence and various potential risk factors. The aim was to analyse the incidence and potential risk factors for PCF formation in a large study set collected over a longer period of time. In the retrospective study at the Department of Otorhinolaryngology and Cervicofacial Surgery of Ljubljana, 422 patients who were treated for head and neck cancer by TL between 2007 and 2020 were included. The comprehensive clinicopathologic data were collected including potential risk factors related to the patient, disease, surgical treatment and post-operative period for the development of fistulae. The patients were categorized into a group with the fistula (a study group) and one without it (a control group). The PCF then developed in 23.9% of patients. The incidence following a primary TL was 20.8% and 32.7% following salvage TL (p = 0.012). The results demonstrated that surgical wound infection, piriform sinus invasion, salvage TL, and total radiation dose were determined as independent risk factors for PCF formation. A diminishing surgical wound infection rate would contribute to a further reduction of the PCF rate.

Identity reconstruction through reflection and reflexivity: a new journey beyond the Ph.D. dissertation

ABSTRACT In the post Ph.D. thesis period, Simon, the only participant in this study was encouraged to reflect on his learning process by his supervisor through interviews. Simon had already reflected on the practice of colleagues during the thesis process; however, this follow-up study brought out the researcher’s own voice. Taking a view of identity that emphasizes the interaction between the personal and the professional, the study reveals that Simon was able to understand how reflection on a wide range of incidents and memories, and the classification and thematising of these, led to insights into his own identity growth. The analysis of his own interview data led to reflection on the connections between different aspects of identity. As the analysis progressed, self-confidence and self-realisation emerged as personal themes, and changed teaching content, and changed relationships with students, as professional themes. The learning in the thesis became subject to greater scrutiny, or meta-reflection, and he was able to compare himself with thesis participants, and insights into his changed identity in relation to them. The links emerging involved his roles as writer, researcher, learner and teacher. Some implications for thesis supervision are provided.

Spectral Splitting as a Route to Promote Total Efficiency of Hybrid Photovoltaic Thermal with a Halide Perovskite Cell

Integrating photovoltaic (PV) perovskite solar cells and photothermal (PT) collectors into a hybrid photovoltaic thermal (PVT) is a promising method to further improve the conversion efficiency of solar energy via salvaging the near‐infrared energy. Herein, a 1D photonic crystal of Si/GeO2 to construct a spectrally selective PV–PT splitter that selectively reflects solar energy in the PV band while absorbing the rest is utilized. The fabricated PV–PT splitter reveals a considerable reflectance of 92.3% in the PV band, a comprehensive absorptance of 52.1% in the PT band, as well as good angular independence over a wide incident range of 0–70°. The hybrid PVT design with the Si/GeO2 spectral splitter/absorber and a perovskite solar cell (PSC) acquires a solar‐to‐electrical efficiency of 29.3% higher than the single PSC (24.6%). In addition, the temperature of PSCs in the hybrid PVT design under 1 kW m−2 solar irradiation can be significantly reduced by 15 °C owing to suppression of ineffectively converted incident photons on the PV cells. This appealing strategy highlights a new avenue for further enhancing the total electrical efficiency via broadening the utilization of the entire solar spectrum in the hybrid PVT design integrated with wide‐bandgap perovskite solar cells.

A Thermally Controlled Multifunctional Metamaterial Absorber with Switchable Wideband Absorption and Transmission at THz Band.

This paper proposes a thermally controlled multifunctional metamaterial absorber with switchable wideband absorption and transmission at the THz band based on resistive film and vanadium dioxide (VO2). The function of the absorber can be adjusted by changing the phase transition characteristics of VO2. When VO2 is in a metallic state, the absorber can achieve wideband absorption with above 90% absorption from 3.31 THz to 10 THz and exhibits excellent absorption performance under a wide range of incident and polarization angles. When VO2 is in an insulating state, the metamaterial acts in transmission mode with a transmission coefficient of up to 61% at 5.15 THz. The transmission region is inside the absorption band, which is very important for practical applications. It has the advantages of having a simple structure, wideband absorption, and switchable absorption/transmission with potential application value in the fields of stealth of communication equipment and radar at the THz band.

The Covariance of PFNS Results from the Chi-Nu Experiment

The prompt fission neutron spectrum (PFNS) from neutron-induced fission is a fundamental quantity for the behavior of nuclear reactors, and has been measured many times on a wide variety of nuclei and covering different ranges of incident and emitted neutron energies. However, results from past measurements are frequently called into question in modern nuclear data evaluations because of a lack of thorough experimental documentation and incomplete uncertainty analyses. The Chi-Nu experiment at Los Alamos National Laboratory was designed to produce high-precision measurements of the PFNS of major actinides over a wide range of incident and emitted neutron energies, and with the documentation and covariance analysis required to ensure that the results of this experiment maintain their impact long into the future, thereby avoiding this pitfall of past measurements. In this work we describe the Chi-Nu experiment along with summaries of the treatment of and methods developed to address two important components of the analysis of Chi-Nu data: random-coincidence backgrounds and MCNP simulations. Furthermore, we describe the first results for correlations not just between all data points collected on a single target nucleus, but also between all data points from separate Chi-Nu measurements on 235U and 239Pu. These correlations are important for accurately calculating ratios of the PFNS from one actinide to another, which are rare and can be informative for nuclear data evaluation efforts.

Adaptive prediction of turbine profile loss and multi-objective optimization in a wide incidence range

The loss prediction model plays a crucial role in turbine design for fast performance prediction and a shorter design cycle. Owing to the design requirements of high-efficiency turbines under a wide range of operating conditions, the loss prediction of the off-design incidence is increasingly important. However, limited by the modeling database and traditional modeling methods, the accuracy and adaptability of the existing off-design incidence loss predictions are insufficient. This paper proposes an adaptive prediction method based on machine learning and develops a multi-objective optimization process based on adaptive prediction. Machine learning (neural network) is applied for more flexible and accurate loss predictions over a wide incidence range. Compared with two classic loss models (Ainley and Mathieson model and Benner model), the adaptive prediction model significantly improves the ability to predict turbine profile loss with off-design incidence, particularly under large incidence conditions. The prediction root mean square error can be reduced by up to 73.8% (absolute value: 0.063). Furthermore, the multi-objective optimization method based on adaptive prediction is applied to the aerodynamic optimization of the original cascades with a wide incidence range. The weighted objective of the optimized cascade (Cri = 0.211) is reduced by 8.7% compared with that of the original cascade (Cri = 0.231). Within the range of full incidence angle (−40° to +20°), the variation of profile loss is reduced by 24.0%. This study is a preliminary exploration aimed at establishing an accurate turbine loss prediction system based on machine learning, the feasibility, and superiority of this approach are confirmed.

Keep minds opening for chronic thromboembolic pulmonary hypertension: More data, less clarity

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare sequelae of pulmonary embolism (PE), resulting from persistent obstruction of pulmonary arteries with non‐resolving thromboemboli and consecutive pulmonary small‐vessel remodeling.1,2 From the landmark research by Pengo et al.3 reporting that the cumulative incidence of CTEPH after acute episode of PE was 3.8% (95% confidence interval [CI] 1.1–6.5) at 2 years, subsequent studies reported a notable wide range of incidences, ranging from 0.1% to 11.8%,4,5 which keep the rationale of routine screening for CTEPH after an episode of PE in intense debate.

Highly efficient transmissive wavefront steering with acoustic metagrating composed of Helmholtz-resonators

Recently, a kind simply structured metasurface made of binary phase modulated meta-unit shows extraordinary beam steering functionality especially in the reflective beam manipulation. In this work, we demonstrate a Helmholtz-resonator based acoustic metagrating for high efficient beam wavefront steering in transmissive configuration. The complex meta-unit of the metagrating made of three Helmholtz-resonators combines traditional diffraction and interference theory with the free phase modulation ability of local resonant periodic structure to coherently control the acoustic wavefront steering. We show numerically and experimentally the anomalous refraction can be acquired with the designed metagrating of subwavelength thickness. By properly designing the geometric parameters of the meta-unit, the −1st order diffraction can be retained, and the unexpected diffraction orders are eliminated through destructive interference for a high efficient anomalous refraction. The anomalous refraction performance of the proposed metagrating is achieved over a wide incident range. The reported structure is promising for high efficient and wide angle complex wavefront engineering in e.g. encryption or communications.

Loss Analysis of Cavity Leakage Flow in a Compressor Cascade

Abstract The cavity flow of shrouded stators is quite complex and not yet completely understood, especially for its loss characteristics. In this paper, a matrix of numerical simulations was designed and conducted to investigate the loss characteristics of the cavity flow in a compressor cascade, with a wide range of incidence, two flow coefficients, and three seal clearances. The effect of the skewed boundary layer was introduced to simulate the practical compressor environment as far as possible. The results show that the total pressure loss coefficient is unable to evaluate the cavity leakage loss correctly since it ignores the temperature rise. With the reduction of the flow coefficient, the entropy loss coefficient and thermal entropy generation rate tend to increase, while the change of the viscous entropy generation rate is dependent on the incidence since the high tangential velocity deteriorates the flow of the pressure side at large negative incidence but significantly improves the flow of the suction side as the incidence increases. In addition, there is a significant difference in loss sensitivity to the seal clearance at various incidences. One of the major reasons is the change of pressure difference between the downstream and upstream. And the other major reason is the distribution difference of the high-loss fluid caused by the variation in the passage vortex. These key findings are able to provide insights leading to reducing the compressor loss due to the cavity leakage flow.