Outer Rings Research Articles

Research on Temperature Rise Characteristics Prediction of Main Shaft Dual-Rotor Rolling Bearings in Aircraft Engines

Traditional aero-engine bearings rotate simultaneously with their inner and outer rings, which makes the temperature rise prediction model computationally large with low accuracy, and it cannot be accurately verified due to the means of testing. This paper presents a method for predicting the temperature rise characteristics of aero-engine bearings under composite load conditions. Firstly, the local method is used to calculate the heat generation from heat sources such as bearing spin, lubricant drag, and the differential sliding of steel ball and collar, respectively, then finite element modelling and steady-state thermal analysis are carried out for aero-engine bearings under the simultaneous action of axial and radial external loads, a double-rotor test setup is designed and the predictive model is validated, and finally, the influences of rotational speed and load on the temperature rise characteristics of the bearings are investigated. The study shows that the aero-engine bearing prediction model proposed in this paper has high accuracy; with the increase in the rotational speed of the inner ring of the bearing, the temperatures of both the inner and outer rings of the bearing increase significantly; the temperatures of the inner and outer rings of the bearing increase with the increase in the axial load, and the effect of the radial load on the temperature of the bearing is not obvious.

A broadband single‐layer reflectarray antenna with split ring element

AbstractA broadband single‐layer reflectarray comprising three‐layer concentric split ring elements is proposed. The reflection phase is achieved by changing the flare angle of the inner and outer split rings. The resonance of the element is easily controlled by varying the relative relationships between the homomorphic patches. And the length of the split ring changes in the azimuth direction, which improves the utilization rate of unit space. The middle split ring acts as a parasitic structure with constant size, making the surface current distribution of the element more uniform to improve the element bandwidth. A reflectarray containing 256 elements is designed and tested. The measured results indicate that the peak gain is 25.3 dBi corresponding to the aperture efficiency of 42%. And the 1‐dB gain bandwidth of the reflectarray of 21.7% is achieved.

The crystal structures and Hirshfeld surface analysis of three new bromo-substituted 3-methyl-1-(phenylsulfonyl)-1H-indole derivatives

Three new 1H-indole derivatives, namely, 2-(bromomethyl)-3-methyl-1-(phenylsulfonyl)-1H-indole, C16H14BrNO2S, (I), 2-[(E)-2-(2-bromo-5-methoxyphenyl)ethenyl]-3-methyl-1-(phenylsulfonyl)-1H-indole, C24H20BrNO3S, (II), and 2-[(E)-2-(2-bromophenyl)ethenyl]-3-methyl-1-(phenylsulfonyl)-1H-indole, C23H18BrNO2S, (III), exhibit nearly orthogonal orientations of their indole ring systems and sulfonyl-bound phenyl rings. Such conformations are favourable for intermolecular bonding involving sets of slipped π–π interactions between the indole systems and mutual C—H...π hydrogen bonds, with the generation of two-dimensional monoperiodic patterns. The latter are found in all three structures, in the form of supramolecular columns with every pair of successive molecules related by inversion. The crystal packing of the compounds is additionally stabilized by weaker slipped π–π interactions between the outer phenyl rings (in II and III) and by weak C—H...O, C—H...Br and C—H...π hydrogen bonds. The structural significance of the different kinds of interactions agree with the results of a Hirshfeld surface analysis and the calculated interaction energies. In particular, the largest interaction energies (up to −60.8 kJ mol−1) are associated with pairing of antiparallel indole systems, while the energetics of weak hydrogen bonds and phenyl π–π interactions are comparable and account for 13–34 kJ mol−1.

Patterns of Progression of Nonproliferative Diabetic Retinopathy Using Non-Invasive Imaging.

To identify progression of nonproliferative diabetic retinopathy (NPDR) in patients with type 2 diabetes by combining optical coherence tomography angiography (OCTA) metrics and color fundus photography (CFP) images. This study was a post hoc analysis of a prospective longitudinal cohort study (CORDIS, NCT03696810) with 2-year duration. This study enrolled 122 eyes. Ophthalmological examinations included OCTA and CFP. OCTA metrics included skeletonized vessel density (SVD) and perfusion density (PD) at the superficial capillary plexus (SCP) and deep capillary plexus (DCP). Microaneurysm turnover analysis and Early Treatment Diabetic Retinopathy Study (ETDRS) grading for diabetic retinopathy (DR) severity assessment were performed on 7-field CFP. Eyes graded as ETDRS level 20 showed significant capillary nonperfusion predominantly in the inner ring area in the SCP (P < 0.001), whereas eyes graded as ETDRS level 35 and ETDRS levels 43 and 47 showed significant capillary nonperfusion in both the SCP and DCP in both inner and outer rings (P < 0.001). When evaluating rates of progression in capillary nonperfusion for the 2-year period of follow-up, changes were found predominantly in the DCP for SVD and PD and were better identified in the outer ring area. Microaneurysm turnover contributes to the characterization of NPDR progression by discriminating ETDRS level 35 from ETDRS levels 43 and 47 (P < 0.001), which could not be achieved using only OCTA metrics. Patterns of progression of NPDR can be identified combining OCTA examinations of the superficial and deep retinal capillary plexi of central retina and determination of microaneurysm turnover from fundus photographs. Our study reports results from a registered clinical trial that advances understanding of disease progression in NPDR.

Slipping in cylindrical roller bearings at the simultaneous rotation of inner and outer rings

Slipping in cylindrical roller bearings is investigated at the simultaneous rotation of inner and outer rings. A 6-DOF dynamic model is developed to analyze roller, cage, and ring dynamics, assessing driven and resistance moments, cage rotating speed, and roller-raceway sliding velocities. The results show that if the inner and outer rings rotate inversely, the motion of rollers is relatively stable, which is beneficial for preventing the slipping in the bearing. However, if the inner and outer rings rotate in the same direction, the churning moment of rollers is high. Meanwhile, more rollers have a negative value of the sum of the churning moment and traction moment. This leads to an increase in the slipping of the bearing.

Investigation of High-Speed Rubbing Behavior of GH4169 Superalloy with SiC/SiC Composites

The silicon carbide fiber-reinforced silicon carbide matrix (SiC/SiC), ceramic matrix composite (CMC) and nickel-based superalloy GH4169 can be utilized in high-temperature applications due to their high-temperature performance. The SiC/SiC composites are commonly used in turbine outer rings, where they encounter friction and wear against the turbine blades. This high-speed rubbing occurs frequently in aircraft engines and steam turbines. To investigate the tribological behavior of these materials, rubbing experiments were conducted between the SiC/SiC and the GH4169 superalloy. The experiments involved varying the blade tip speeds ranging from 100 m/s to 350 m/s and incursion rates from 5 μm/s to 50 μm/s at room temperature. Additionally, experiments were conducted at high temperatures to compare the tribological behavior under ambient conditions. The results indicated that the GH4169 superalloy exhibited abrasive furrow wear during rubbing at both room temperature and high temperature. Furthermore, at elevated temperatures, some of the GH4169 superalloy adhered to the surface of the SiC/SiC. The analysis of the experiments conducted at ambient temperatures revealed that the friction coefficient increased with higher blade tip velocities (100~350 m/s). However, the coefficient was lower at high temperatures compared to room temperature. Furthermore, significant temperature increases were observed during rubbing at room temperature, whereas minimal temperature changes were detected on the rubbing surface at high temperatures.

Test Method for Rapid Prediction of Steady-State Temperature of Outer Rings of Bearings under Grease Lubrication Conditions

Temperature has a great influence on the stability of bearing performance. For the study of bearing steady-state temperature, this paper proposes a test method to quickly predict the steady-state temperature of the outer ring of a bearing, which solves the problems in traditional theoretical calculations and simulation analysis methods such as the large number of calculations, complex models, and large errors. Firstly, a mathematical prediction model is established according to the bearing temperature-rise law; then, a bearing steady-state temperature detection device is designed; and finally, the prediction model parameters are solved according to the experimental results, and experimental verification is carried out. It is shown that the prediction model has high accuracy under different load and speed conditions, and the error between the predicted steady-state temperature and the tested steady-state temperature is less than 0.7 °C. This prediction method reduces the single test time of the same speed to 60 min, which greatly improves the efficiency of the temperature detection test. The steady-state temperature model has important theoretical significance in guiding the study of the limiting speed of bearings.

Dynamic PB metasurface for transmissive and reflective wavefront manipulation

Based on the phase transition characteristics of vanadium dioxide (changes in conductivity with temperature), we designed a dynamic metasurface for wavefront manipulation that can switch between transmission and reflection modes at the same frequency. When vanadium dioxide is in the metallic state, the metasurface operates in reflection mode, while it is in the insulating state, it works in transmission mode. The phase distributions of the two operating modes are different and can be easily adjusted by rotating the inner and outer rings. At the frequency of 1.3 THz, we designed a metasurface that can switch between anomalous reflection and refraction with different deflection angles. Additionally, we created a switchable metalens that provides different focal lengths in reflection and transmission modes. The tunable metasurface can provide innovative design possibilities for dynamical wavefront manipulation.

Long-lasting farside volcanism in the Apollo basin: Chang'e-6 landing site

A major lunar scientific question is the cause of the paucity of farside mare basalts. The South Pole-Aitken Basin (SPA) is the largest (2400×2050 km) and most ancient lunar impact basin. The Apollo peak-ring basin, the largest impact feature within the SPA, is located on its northeast edge in a transitional zone of crustal thickness and compositions. The Chang'e-6 (CE-6) mission, the first sample-return mission to the lunar farside, is targeted to land in the southern Apollo basin, sampling farside mare basalts with critical insights into early lunar evolution. In preparation for the CE-6 sample return, we conducted a comprehensive study of Apollo basin volcanism. We found that volcanic activity began in the Nectarian Period (∼4.05 Ga) (cryptomaria) and continued into the Eratosthenian Period (∼1.79 Ga). At least two Imbrian-aged episodes of eruptions occurred in the southern part of the Apollo basin where CE-6 is targeted to land. At ∼3.35 Ga, low-Ti (∼3.2 wt %) volcanism was active, and its products covered the entire low topographic region of the southern Apollo basin, between the inner and outer rings. Closely following its eruption at ∼3.07 Ga, high-Ti basalts (∼6.2 wt %) erupted close to the Chaffee S crater and flowed east with decreasing thickness until encountering proto-wrinkle ridges. In addition, volcanic activity in the region is significantly correlated with low crustal thickness, primarily thinned by the SPA and Apollo impact events. For regions of intermediate-thick crust (Oppenheimer crater), dikes stalled under the crater floor, spreading to form sills and a floor-fractured crater. For thin crust regions (Apollo basin interior), dikes erupted directly, forming extensive lava flows. In areas of thick highland crust, we see no evidence of extrusive activity or floor-fractured craters, suggesting that dikes there do not reach the surface and are intrusive. CE-6 samples returned from the unique geological setting will provide significant petrogenetic information to address further the paucity of farside mare basalts and the lunar nearside-farside dichotomy. To solve those scientific questions, the high-Ti mare region in south Apollo basin is recommended as the priority landing site.

ВПЛИВ УМОВ РОБОТИ НА ТЕМПЕРАТУРНИЙ РЕЖИМ ПІДШИПНИКІВ З МЕТАЛЕВИМИ ТА КЕРАМІЧНИМИ КУЛЬКАМИ

The results of an experimental study of the temperature mode of operation of rolling bearings under different lubrication conditions are presented. Comparative tests of all-metal bearings and similar bearings with rolling elements made of silicon nitride (hybrid bearings) when lubricated with an oil jet and an oil-air mixture in the range of rotor rotation frequencies from 0 to 35000 rpm were carried out. For the experiments, a specially created set was used, which allows you to study the temperature of the bearings and the temperature of the lubricant at the entrance and exit from the bearings. The axial load on the bearings was created with the help of a compression spring, which rested on the outer rings of the bearings. This made it possible to close the load inside the system. During the tests, the load was 0 N, 1000 N, and 2000 N. Tests were carried out for two modes of bearing lubrication: oil jet and oil-air mixture. The method of measuring the temperature of the outer ring of bearings is described. The temperature measurement error was considered as a complex of instrumental error and method error. It was assumed that the temperature error is subject to a normal distribution. The conducted analysis showed that the error of measuring the temperature of the bearing ring was ± 2.8 °C with a confidence probability of 95 %. It has been established that bearings with ceramic balls in the entire studied range behave qualitatively and quantitatively in approximately the same way as with steel ones. The temperature level of hybrid bearings is slightly higher when lubricated with both an oil jet and an oil-air mixture. There is a clear connection between the values of the bearing temperature and the moment of resistance in the bearing: the increase in temperature is observed under the same conditions under which the moment of resistance increases.

Radially oriented Ni3(HITP)2 microspheres as high-performance anode materials for Li-ion capacitors with exceptional energy density and cycling stability

Developing of high-energy, high-power-density energy storage devices is challenging. Despite being promising electrode materials for these devices, metal–organic frameworks (MOFs) have poor electrical conductivity and weak ligand–metal coordination. Here, the highly conductive MOF, Ni3(HITP)2, which comprises radially oriented microspheres, is adopted as the anode for Li-ion capacitors (LICs). The half-cell demonstrates high reversible capacity (834 mAh g−1) at 50 mA g−1 with minimal capacity reduction, attributable to the participation of C and N functional groups of the ligand and Ni2+ in the redox reactions during charge/discharge. Especially, density functional theory calculations show that, apart from the inner rings, participation of the outer rings of Ni3(HITP)2 in the redox reactions is responsible for the high Li + storage capacity. An LIC with a Ni3(HITP)2 anode and commercial activated-carbon cathode demonstrates high specific energy (120.7 Wh kg−1) at 89.2 W kg−1, nearly twice as high as that of graphite-based LICs, and maintains specific energy of 25.8 Wh kg−1 even at high specific power (7.16 kW kg−1), over the range 1–4.4 V, along with high cycling stability (76% capacity retention over 10000 cycles). The proposed radially oriented Ni3(HITP)2 microspheres have potential for application as the anode in high-performance energy storage devices.

Анализ остаточной намагниченности наружных колец подшипников буксового узла колесной пары при их размагничивании на установке УМДП-01

Objective: to compare the readings of the residual magnetization of the outer ring of the bearing with its different orientation with respect to the magnetizing field on the example of the UMDP-01 installation. To show in practice the inefficiency of using the technology of demagnetization of the outer rings of the bearings of axle boxes when they are located in a horizontal plane. Methods: comparison of the obtained values of the residual magnetization by direct measurements during demagnetization of the outer rings in the horizontal and vertical planes with respect to the magnetic field. In practice, the same conditions for magnetization and demagnetization of the same outer ring were observed by passing a pulsed current through the solenoid and the contact rod in the magnetization mode and gradually reducing the alternating current in the solenoid for the demagnetization mode. Results: the experiment showed that the values of the residual magnetization of the outer ring during the full cycle of its demagnetization in the horizontal plane on the UMDP-01 installation are higher than when it is demagnetized in the vertical plane. The vertical placement of the ring in the center of the solenoid allowed it to be demagnetized from the first time in position A with an incomplete demagnetization cycle. Practical significance: the article shows that the technology of demagnetization of bearing rings in the horizontal plane, as required by the operating manual 9402.00.000 RE, often leads to a violation of the requirements of regulatory documents in terms of permissible values of residual magnetization. Demagnetization of the outer rings in the vertical plane will lead to full satisfaction of the requirements of regulatory documents, increase the productivity of magnetic powder control in general by reducing the demagnetization cycle and simplifying technological transitions associated with the complexity of installing the object of control in the horizontal plane.

Design and analysis of a highly uniform five-band terahertz filter based on frequency selective surface

In this paper, a highly uniform five-band terahertz filter is presented, achieved by deforming two nested square ring structures. The metal pattern layer of the filter comprises a nested square ring structure with an inner and outer opening, and a metal strip connecting the inner and outer rings. Symmetrical openings divide nested square rings, breaking the current path and generating multiple metal bars of different lengths to excite dipole oscillations. Using metal strips to connect the inner and outer rings, the inner and outer resonant structures are integrated. Compared to a single resonant particle, the coupling of different single resonant particles amplifies the resonance of the combined structure, resulting in a wider stopband width and enhanced isolation between multiple passbands. A metal strip is also added to both ends of the outer ring opening to increase the equivalent capacitance of the outer ring, enhance the resonance, and improve out-of-band suppression. The transmission spectrum has five uniform passbands in the range of 1.3807–1.9917 THz, and the maximum passband ratio (MPR) of 3 dB bandwidth is about 1.16, and the ratio of 10 dB is about 1.17. The transmission coefficient of transmission zero is about 0.1, and the peak transmission coefficient of transmission peak is close to 1. The polarization of TE and TM incident waves is stable, and the filtering characteristics are good. Besides, the rectangular coefficients of the five passbands are all less than 1.33, showing excellent band selectivity. The resonance mechanism is explained by the Q value and electric field current distribution. The influence of structural parameter changes on filtering characteristics is also analyzed, and the main control parameters are found by using correlation analysis tools. From the changes in the MPR curve, it is verified that the structure parameters of the designed filter are in good condition. The multi-passband filter designed in this paper has uniform filtering characteristics, which is helpful to the development of terahertz multi-channel communication.

Analysis of Kinematics and Dynamics of Rolling Ring Based on Finite Element Method

The working performance of the conductive rolling ring has a crucial impact on the overall energy security and on-orbit life of a satellite. To ensure the real-time transmission of signal and current, it is necessary to control the motion pattern of the rolling ring. In this paper, the finite element analysis method is used to carry out kinematics and dynamics simulation analysis, analyze the motion stability of the rolling ring, and discuss the relationship between the size of the idler gear, the driving torque, and the flexible contact pressure. The research results show that the numerical simulation and theoretical analysis show that the deviation angle is between 0 and 1.52 when the initial installation of the rolling ring is deviated by using the existing camber design of the inner and outer rings. Both have a self-recovery function. The driving torque and the size of the idler gear are nonlinear, and the contact force is proportional to the radius of the idler gear. With the increase in the compression of the radius of the flexible ring, the driving torque and the contact force will increase accordingly. The method of reducing the compression or increasing the size of the idler gear can be used to reduce the driving torque and maintain a certain contact to facilitate the transmission of electrical signals.

On-shaft ball bearings monitoring by using an inertial measurement unit (IMU): defects severity signatures under stationary and non-stationary conditions

The present work focuses on the using of an inertial measurement unit (IMU) to monitor the signatures of defects in ball bearings under stationary and non-stationary regimes. The present paper completes the existing literature for both regimes by (i) investigating the influence of IMU parameters on signals derived from six axes and by (ii) proposing signal processing methodologies to detect defects in outer and inner rings. Defects are both declined on the inner and outer rings in five severities, and are studied at six rotation speeds (5 rpm to 400 rpm) and five radial loads (100 kg to 500 kg). Detection and diagnostic were made qualitatively and summarize in tables. Two different methods for processing the non-stationary regime signals are compared. Our results open new ways on the improvement of inertial units and their application.

Influence mechanism of impingement and film on the flow and heat transfer of turbine outer ring with composite cooling structure under different operating parameters

Two typical turbine outer rings with impingement-film composite cooling structure and single film cooling structure are selected as the research object, the mechanism of temperature ratio (τ = 1.2 ∼ 1.6), blowing ratio (M = 0.7 ∼ 3.0) and Mach number (Ma = 0.2 ∼ 0.8) on the flow and heat transfer of the two outer rings under engineering application is explored, which serves as a foundation for designing turbine outer ring cooling of aero-engine with different thermal load characteristics. It is indicated that compared to single film cooling, impingement-film composite cooling improves the cooling performance on the outer ring surface, while also effectively reduces the localized regions of low cooling property, enhancing the even distribution of cooling effectiveness. In the impingement-film composite cooling structure, film cooling is the primary factor determining the cooling property of outer ring. Among the influencing factors, Mach number has the greatest impact (64 % ∼ 83 %), followed by blowing ratio. Under different temperature ratios, film cooling accounts for approximately 80 % of the cooling property. At high blowing ratio, impingement-film composite cooling outperforms single film cooling in terms of cooling enhancement and effectiveness. Increasing blowing ratio (0.7 ∼ 2.0) enhances the cooling contribution of impingement in composite cooling, while the cooling contribution remains constant at 18 % as the blowing ratio enhances from 2.0 to 3.0. When Mach number increases, impingement-film composite cooling experiences a smaller decrease in cooling effectiveness compared to single film cooling, leading to better cooling uniformity. At high Mach number, impingement cooling effectively mitigates the decreasing cooling trend in the middle region of the outer ring. Additionally, the proportion of cooling performance in composite cooling increases, thereby reducing the adverse impact of the sharp decrease in film cooling property with elevating Mach number on the overall performance of composite cooling.

Revealing ringed galaxies in group environments

Aims. We explore galaxies with ringed structures inhabiting poor and rich groups with the aim of assessing the effects of local density environments on ringed galaxy properties. Methods. We identified galaxies with inner, outer, nuclear, inner+outer (inner and outer rings combined), and partial rings that reside in groups by cross-correlating a sample of ringed galaxies with a group catalog obtained from Sloan Digital Sky Survey (SDSS). The resulting sample was divided based on group richness, with groups having 3 ≤ Nrich ≤ 10 members classified as poor, while groups having 11 ≤ Nrich ≤ 50 were classified as rich. To quantify the effects of rings and the role of local density environment on galaxy properties, we constructed a suitable control sample for each catalog of ringed galaxies in poor and rich groups, consisting of non-ringed galaxies with similar values for the redshift, magnitude, morphology, group masses, and environmental density distributions as those of ringed ones. We explored the occurrence of ringed galaxies in poor and rich groups and analyzed several galaxy properties, such as star formation activity, stellar populations, and colors, with respect to the corresponding comparison samples. Results. We obtained a sample of 637 ringed galaxies residing in groups. We found that about 76% of these galaxies inhabit poor groups, whereas only about 24% are present in rich groups. Inner rings are prevalent in both rich and poor groups, while nuclear rings are the least common in both groups. Regarding the control sample, about 81% galaxies are found in poor groups and about 19% in rich ones. We find that the percentages of ringed galaxies with bar structures are similar, regardless of whether the group is rich or poor. In addition, ringed galaxies inhabiting groups display a reduction in their star formation activity and aged stellar populations, compared to non-ringed ones in the corresponding control samples. However, the star formation rate is higher for nuclear rings in poor groups than for other types. This disparity may stem from the environmental influence on the internal processes of galaxies, either enhancing or diminishing star formation. Ringed galaxies also show an excess of red colors and tend to populate the green valley and the red sequence of color-magnitude and color-color diagrams, with a surplus of galaxies in the red sequence, while non-ringed galaxies are found in the green valley and the blue region. These trends are more significant in galaxies with ringed structures residing in rich groups. Our findings provide valuable insights into the relationship between ringed structures and their surrounding environments, paving the way for further explorations in this area of study.

Wheel Replacing Pyramid: Better Paradigm Representing Totality of Evidence-Based Medicine.

Evidence-based medicine (EBM), as originally conceived, used all types of peer-reviewed evidence to guide medical practice and decision-making. During the SARS-CoV-2 Coronavirus disease (COVID-19) pandemic, the standard usage of EBM, modeled by the Evidence-Based Medicine Pyramid, undermined EBM by incorrectly using pyramid levels to assign relative quality. The resulting pyramid-based thinking is biased against reports both in levels beneath randomized control trials (RCTs) and those omitted from the pyramid entirely. Thus, much of the evidence was ignored. Our desire for a more encompassing and effective medical decision-making process to apply to repurposed drugs led us to develop an alternative to the EBM Pyramid for EBM. Herein, we propose the totality of evidence (T-EBM) wheel. To create an easily understood graphic that models EBM by incorporating all peer-reviewed evidence that applies to both new and repurposed medicines, and to demonstrate its potential utility using ivermectin as a case study. The graphics were produced using Microsoft Office Visio Professional 2003 except for part of the T-EBM wheel sunburst chart, which was produced using Microsoft 365 Excel. For the case study, PubMed® was used by searching for peer-reviewed reports containing "ivermectin" and either "covid" or "sars" in the title. Reports were filtered for those using ivermectin-based protocols in the treatment of COVID-19. The resulting 265 reports were evaluated for their study design types and treatment outcomes. The three-ringed graphical T-EBM wheel was composed of two inner rings showing all types of reports and an outer ring showing outcomes for each type. The T-EBM wheel avoids the biases of the EBM Pyramid and includes all types of reports in the pyramid along with reports such as population and mechanistic studies. In both early and late stages of medical emergencies, pyramid-based thinking may overlook indications of efficacy in regions of the T-EBM wheel beyond RCTs. This is especially true when searching for ways to prevent and treat a novel disease with repurposed therapeutics before RCTs, safety assessments, and mechanisms of action of novel therapeutics are established. As such, T-EBM Wheels should replace the EBM Pyramids in medical decision-making and education. T-EBM Wheels can be expanded upon by implementing multiple outer rings, one for each different kind of outcome (efficacy, safety, etc.). A T-EBM Wheel can be created for any proprietary or generic medicine. The ivermectin (IVM) T-EBM Wheel displays the efficacy of IVM-based treatments of COVID-19 in a color-coded graphic, visualizing each type of evidence and the proportions of each of their outcomes (positive, inconclusive, negative).

Spatial pattern of urban forest diversity and its potential drivers in a snow climate city, Northeast China

Urban forest diversity is the cornerstone of providing ecosystem services and improving urban environment. However, the spatial pattern of urban forest (UF) diversity and its driving mechanisms are still not well understood. In our study, using 330 UF sample plots and the corresponding plot-based standard deviation values of remote sensing parameters with different spatial resolutions, we developed prediction models for the spatial pattern of UF diversity, and the driving factors of UF diversity were further explored in our study. Our findings indicated that the 3-m spatial resolution of remote sensing was optimal for predicting UF diversity. Both excessively high and excessively low resolutions can increase misclassification errors. In addition, among the three prediction models, the boosted regression trees (BRT) model exhibited greater robustness than the support vector machine (SVM) and random forest (RF) models for predicting UF diversity. UF species were abundant, with 112 tree species in Changchun City. Spatially, the UF diversity showed a significant gradient decreasing trend from suburban areas (outer rings) to downtown areas. We also observed higher diversity in the older communities with high housing prices, supporting the “legacy effect and luxury effect”. Additionally, our research revealed that socioeconomic factors, landscape cover, and patterns collectively explained 41.25% of the UF diversity variation, wherein socioeconomic factors contributed the most variation (17.33%). We further found that UF diversity does not increase more with increasing house prices when the house prices are higher than ¥ 12,000/m2. The higher patch density reduced UF diversity, while a higher UF landscape shape index (LSI) promoted diversity. The LSI threshold, which significantly impacted UF diversity, was about 12. Our research showed that high-resolution remote sensing offers a rapid, cost-effective approach to acquire UF diversity patterns, which could enhance urban forest diversity and contribute to sustainable urban development.

Polarization insensitive passive loaded wideband metamaterial absorber

Abstract This paper proposes a lightweight frequency selective surface polarization-insensitive wideband metamaterial absorber in C band and X band that employs only a few resistive elements. The proposed absorber is embodied with four quadrature slotted inner circular patch, which is horizontally and vertically bisected, and outer concentric copper rings of 0.035 mm thickness are attached with four lumped resistors placed at 90° apart. A slotted inner circular patch provides significant inductive and capacitive loading. The absorption bandwidth of 8.02 GHz with more than 90% absorption is observed from 5.69 to 13.71 GHz under normal incidence and maintains almost same absorptivity range under oblique incidence up to 45° in both transverse electric mode and transverse magnetic mode. The designed metamaterial absorber is fabricated and measured using free space measurement technique. The actual experiments and the simulated ones are in good agreement.