bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-Dimensional Printed, Dual-Band, Dual-Circularly Polarized Antenna Array Using Gap Waveguide Technology
Authors: Wu Sifan , Li Jianxing , Cao Yuanxi , Yan Sen , Xu Kaida , Luyen Hung
Published: October 2022

A gap waveguide (GW)-based 4 × 4 dual-band, dual-circularly polarized antenna array is proposed. The antenna is composed of two stacked layers which are responsible for right-handed circularly polarized (RHCP) radiation in K-band and left-handed circularly polarized (LHCP) radiation in Ka-band. Each stacked layer consists of a GW power distribution network to excite 16 radiating units from a single input. A waffle grid is mounted on top of the array structure to increase effective aperture areas and reduce grating lobes. A prototype was fabricated using stereo lithography appearance (SLA) 3D printing and metallization technology, which significantly decreased the fabrication cost and complexity. Measurement results for the antenna prototype demonstrate the operating bandwidths of 19.91–20.52 GHz in K-band and 28.26–29.19 GHz in Ka-band, over which the reflection coefficients of <−10 dB and axial ratios of <3 dB are achieved. The prototype provides peak gains of 20.1 and 20.3 dB with total efficiencies of >90% in the two respective bands. The combination of dual-band, dual-circularly polarized capability, high gain, high efficiency, lightweight, low cost and compact size renders the proposed design a potential candidate for commercial millimeter wave communication applications.
Efficient Realization for Third-Order Volterra Filter Based on Singular Value Decomposition
Authors: Nakahira Yuya , Iwai Kenta , Kajikawa Yoshinobu
Published: October 2022

Nonlinear distortion in loudspeaker systems degrades sound quality and must be properly compensated for by linearization techniques. One technique to reduce nonlinear distortion is to use a Volterra Filter, which approximates the nonlinearity of the target loudspeaker using the Volterra series expansion. In general, the Volterra Filter is computationally very expensive, and the amount of computation needs to be reduced for real-time processing. In this paper, we propose an efficient implementation of the third-order Volterra filter based on singular value decomposition. The proposed method determines the necessary coefficients based on the symmetry of the third-order Volterra filter and applies singular value decomposition to them. In the filter structure consisting of singular values and their corresponding singular vector, the computational complexity of the third-order Volterra filter can be reduced by eliminating the part of the filter with small singular values. By focusing on the magnitude of the singular values, the proposed method can improve the computational efficiency of the third-order Volterra filter without decreasing its approximation accuracy. Simulation results show that the proposed method can improve the computational efficiency by 60% while maintaining the nonlinear distortion compensation performance of the micro-speaker for smartphones by about 8 dB.
Space Object and Background Polarization Models and Detectability Analysis
Authors: Fu Qiang , Zhao Feng , Chen Hongyi , Zhu Rui , Li Yingchao
Published: October 2022

During the daytime, the commonly used optical intensity imaging techniques for spacecraft detection usually lead to poor detection due to strong background noise. Since some materials with low reflectivity in the visible band have higher reflectivity in the near-infrared band and less sky background noise, this paper carries out a study of near-infrared polarization detection techniques. In this paper, firstly, the parameters in the pBRDF model of common materials are inverted and found to be improved compared with the literature, and secondly, a complex spherical projection is proposed to represent the polarization degree and polarization angle information of the sky background, and this projection has less aberration than the direct projection. Finally, from the above, the polarization detection contrast range and the original intensity contrast range are calculated, and it is found that the maximum of the former is higher than the latter in some angles.
COVID-19 CXR Classification: Applying Domain Extension Transfer Learning and Deep Learning
Authors: Park KwangJin , Choi YoungJin , Lee HongChul
Published: October 2022

The infectious coronavirus disease-19 (COVID-19) is a viral disease that affects the lungs, which caused great havoc when the epidemic rapidly spread around the world. Polymerase chain reaction (PCR) tests are conducted to screen for COVID-19 and respond to quarantine measures. However, PCR tests take a considerable amount of time to confirm the test results. Therefore, to supplement the accuracy and quickness of a COVID-19 diagnosis, we proposed an effective deep learning methodology as a quarantine response through COVID-19 chest X-ray image classification based on domain extension transfer learning. As part of the data preprocessing, contrast limited adaptive histogram equalization was applied to chest X-ray images using Medical Information Mart for Intensive Care (MIMIC)-IV obtained from the Beth Israel Deaconess Medical Center. The classification of the COVID-19 X-ray images was conducted using a pretrained ResNet-50. We also visualized and interpreted the classification performance of the model through explainable artificial intelligence and performed statistical tests to validate the reliability of the model. The proposed method correctly classified images with 96.7% accuracy, an improvement of about 9.9% over the reference model. This study is expected to help medical staff make an integrated decision in selecting the first confirmed case and contribute to suppressing the spread of the virus in the community.
Characteristics of Sepsis or Acute Pyelonephritis Combined with Ureteral Stone in the United States: A Retrospective Analysis of Large National Cohort
Authors: Del Giudice Francesco , Yoo Koo Han , Lee Sinyeong , Oh Jin Kyu , Cho Hyuk Jin , Kim Sang Youn , Min Gyeong Eun , Lee Sang Hyub , Kim Wansuk , Li Shufeng , Wei Wuran , Huang Jianlin , Brown David R. , Spradling Kyle , Basran Satvir , Belladelli Federico , Autorino Riccardo , Pandolfo Savio Domenico , Crivellaro Simone , Crocetto Felice , Ferro Matteo , Asero Vincenzo , Scornajenghi Carlo Maria , Bologna Eugenio , Sciarra Alessandro , Salciccia Stefano , De Berardinis Ettore , Ricciuti Gian Piero , van Uem Stefanie , Conti Simon , Chung Benjamin I.
Published: October 2022

To identify the characteristics of patients with sepsis or acute pyelonephritis (APN) combined with ureteral calculi and to analyze the risk factors in its causation. Methods: We included patients with sepsis or APN caused by ureteral calculi who received treatment in the United States from January 2003 to December 2017 using the Optum® deidentified Clinformatics® Datamart. Demographic factors and risk factors for the receipt of sepsis or APN were subsequently analyzed for statistical significance. Results: Of 467,502 urinary stone patients, age-matched multivariate analysis revealed that a history of urinary tract infection (OR 11.31, 95% CI 10.68–11.99, p < 0.0001) and female gender (OR 2.73, 95% CI 2.62–2.84, p < 0.0001) were significantly related to an increased risk of sepsis or APN. Conversely, a previous past medical history of urolithiasis (OR 0.91, 95% CI 0.87–0.95, p < 0.0001) and cancer (OR 0.91, 95% CI 0.87–0.95, p < 0.0001) were associated with a decreased risk of sepsis or APN. With regards to comorbidities, when more than one comorbidity was present, there was an additive effect with higher OR point estimates, rising to 11.31 (10.68–11.99) when three or more comorbidities present. History of urinary tract infection and female gender are risk factors for sepsis or APN in patients with ureteral calculi. Conclusions: This large national cohort reveals the characteristics of sepsis or APN combined with ureteral stone and provides an important baseline for the treatment of urolithiasis in the future.
Bicruciate-Retaining Total Knee Arthroplasty: State of the Art for the Younger and Active Population? A Systematic Review and Future Prospective
Authors: De Windt Tommy S. , Van Laarhoven Simon N. , Van Hellemondt Gijs G.
Published: October 2022

(1) Background: Total knee arthroplasty (TKA) is a well-established surgical treatment for end-stage osteoarthritis. While no leading factor can be identified, the high frequency of patient dissatisfaction (20%) pertains to several key features such as preoperative expectations and postoperative improvement in knee function. Bicruciate-retaining total knee arthroplasty (BCR-TKA) may improve kinematics and lead to improved clinical outcome in the higher-demanding patients. (2) Methods: A systematic review of the literature was performed to assess the best available preclinical and clinical literature on BCR-TKA for kinematics and clinical outcome and adverse events such as implant loosening. Articles were screened using predefined in- and exclusion criteria. The guidelines for Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) were used. (3) Results: The literature search resulted in 352 articles which were screened for title and abstract. After application of the in- and exclusion criteria, 13 preclinical and 30 clinical articles were included. The methodological quality of studies was low, including mainly level IV studies. (4) Conclusions: This is the first report that provides a systematic description of the broad available preclinical and clinical literature on BCR-TKA. It underlines the current interest in improving kinematics and clinical outcome based on a more anatomical TKA design. The current review demonstrates the low methodological quality of clinical trials that have investigated BCR-TKA. Currently, there are insufficient data to support broad (“state of the art”) implantation of BCR-TKA. Preclinical and clinical research suggest, however, that the design has a potential benefit to achieve improved kinematics in the young and active arthroplasty patient and warrants future research for new-generation designs with optimal (tibial) fixation and reproducible (robot or navigated) surgical placement.
Production of Photovoltaic Electricity at Different Sites in Algeria
Authors: Bouziane Khadidja , Chaouch Noura , Ouahrani Mohammed Redha , Laouini Salah Eddine , Bouafia Abderrhmane , Ali Gomaa A. M. , Marwani Hadi M. , Rahman Mohammed M. , Menaa Farid
Published: October 2022

The necessity for further growth in the demand for electricity, particularly in the remote countryside, has been essential to Algeria’s economic and social progress in recent years. The Saharan regions account for around 80% of Algeria’s surface and have significant power demands. These areas are distinguished by their scattered population, extremely hot weather with high radiation levels (7 kw h/m2/day), and minimal energy use. Photovoltaic technology is one of the finest ways to harness solar power. The conversion of radiant energy (light quanta) into electrical energy can be achieved with the use of semiconductor materials. The effects of a solar cell depend on parameters such as solar cell technology, the position of the photovoltaic array, climate, and geographic data of the site. This paper presented: the role of site choice in the production of photovoltaic electricity. The results obtained for five sites in Algeria: Ouargla, Algers, Bechar, Sidi Bel Abbès, and Batna, confirmed that desert sites (Ouargla, Bechar) have a good photovoltaic efficiency result with large solar power irradiance.
Uncertainty-Based Comprehensive Optimization Design for the Thermal Protection System of Hypersonic Wing Structure
Authors: Wang Ruixing , Luo Yan
Published: October 2022

Due to the inherent uncertainties in material properties, loads, geometric dimensions, et al., the uncertainty-based optimization design method has become increasingly important for the design of the thermal protection system (TPS) by carefully considering the influences of uncertainties. In this study, an uncertainty-based comprehensive optimization design method, which sequentially performs the robust design of aerodynamic shape and structure size for the TPS of a hypersonic wing is proposed, on the presence of uncertain-but-bounded parameters. The robust design of the TPS’s aerodynamic shape is firstly carried out. The results show that the proposed method decreases the fluctuation of the lift-to-drag ratio by 5.7%, with a small increase of heat flux on the stagnation point by only 0.13% when compared with the conventional deterministic optimization method. After that, based on the optimized aerodynamic shape and heating loads, the robust design of the multilayer TPS tile is conducted. The results show that the mass of the TPS tile efficiently deceased from 2.713 kg to 2.445 kg by 9.89%, and the robustness of the optimized design is better than the initial design. Finally, the effectiveness of the proposed optimization method is validated by the heat insulting experiment of the typical multilayer TPS tiles.
Default Detection Rate-Dependent Software Reliability Model with Imperfect Debugging
Authors: Zhang Ce , Lv Wei-Gong , Sheng Sheng , Wang Jin-Yong , Su Jia-Yao , Meng Fan-Chao
Published: October 2022

From the perspective of FDR (fault detection rate), which is an indispensable component in reliability modeling, this paper proposes two kinds of reliability models under imperfect debugging. This model is a relatively flexible and unified software reliability growth model. First, this paper examines the incomplete phenomenon of debugging and fault repair and established a unified imperfect debugging framework model related to FDR, which is called imperfect debugging type I. Furthermore, it considers the introduction of new faults during debugging and establishes a unified imperfect debugging framework model that supports multiple FDRs, called imperfect debugging type II. Finally, a series of specific reliability models are derived by integrating multiple specific FDRs into two types of imperfect debugging framework models. Based on the analysis of the two kinds of imperfect debugging models on multiple public failure data sets, and the analysis of model performance differences from the perspective of fitting metrics and prediction research, a fault detection rate function that can better describe the fault detection process is found. By incorporating this fault detection rate function into the two types of imperfect debugging models, a more accurate model is obtained, which not only has excellent performance and is superior to other models but also describes the real testing process more accurately and will guide software testers to quantitatively improve software reliability.
Migration and Diffusion of Surface Sediments in Bohai Bay: Evidence from Grain Size and Elements
Authors: Zhao Bo , Zhang Lianjie , Yan Jishun , Lin Xia , Wang Peng , Zhang Pan , Yu Yonghai , Yu Shuai
Published: October 2022

Grain size and element content of surface sediment from Bohai Bay were analyzed to study the sediment migration and diffusion based on grain size trend analysis (GSTA) and discriminant function (DF). The sediment in the southern, central and western part of Bohai Bay mainly originates from the Yellow River, while that in the northern part of Bohai Bay mainly originates from the Luanhe River. The influence boundary between the Yellow River and the Luanhe River is estimated to be at 38°50′ N. In both the southern and northern parts of Bohai Bay, sediment is transported into the bay under the influence of prevailing waves, strongest waves and tidal remnants, resulting in sediment accumulation in western Bohai Bay. The coastal sediment of Bohai Bay is generally in a state of offshore movement, which is consistent with the large-scale coastline retreat in past decades found by previous studies.
Analysis of Temperature and Thermal Stress for a Solar Power Tower Molten Salt Receiver under Multi-Source Uncertainties
Authors: Luo Yan , Li Gen , Wang Zhiyuan , Lu Tao
Published: October 2022

Although uncertainties such as solar radiation and material properties are generally involved in the solar receiver design process, current studies in the solar receiver field are based on deterministic models and do not incorporate these uncertainties into the design process. In this paper, based on a coupled deterministic thermal–structural model and an uncertainty analysis model, an analysis of temperature and thermal stress was conducted for a solar power tower (SPT) molten salt receiver under multi-source uncertainties to investigate the dispersions of responses. The results demonstrated that the maximum temperature inside the tube wall under multi-source uncertainties ranged from 847 K to 895 K, with an expectation of 871 K and a standard deviation of 8 K, and the maximum thermal stress ranged from 173 MPa to 245 MPa, with an expectation of 204 MPa and a standard deviation of 12 MPa, both of which had severer probabilities than the deterministic results (871 K and 204 MPa) and may cause failure in the receiver. Furthermore, the results of the global sensitivity analysis indicated that the peak incident solar flux was the most sensitive, and the specific heat of the tube material was the least sensitive to the maximum temperature and thermal stress of the tube wall. These results are beneficial to provide additional reliability and confidence in the temperature and thermal stress evaluation process of solar receiver tubes.
Triaxial Experimental Study of Zinc Contaminated Red Clay under Different Temperature Conditions
Authors: Wang Jianqiang , Song Yu , Dong Shuaishuai , Ding Song , Geng Yukun , Gao Xiaotong
Published: October 2022

Temperature is one of the important factors affecting the mechanical properties of geotechnical soils, and its role in engineering construction in China cannot be underestimated. In order to study the effects of temperature and zinc contamination concentration on the mechanical properties of Guilin local red clay, a temperature-controlled triaxial shear test was conducted on Guilin red clay under three variables of temperature, zinc contamination concentration and surrounding pressure. The test findings revealed that there are significant differences in the effects of temperature, zinc contamination concentration and surrounding pressure on the mechanical properties of Guilin red clay. The stress–strain curves of the red clay at various temperatures, contamination concentrations and envelope pressures are of the strain-hardening type, and the deformation modulus showed a tendency to increase rapidly with increasing strain, then decrease rapidly, and finally, decrease slowly. With the increase of temperature, the cohesion of Zn-contaminated red clay increases, while the angle of internal friction increases and then decreases, both of which increase the shear strength of red clay. As the concentration of Zn contamination grows, the shear strength of the red clay increases, while the internal friction angle increases and then decreases, and the shear strength of the soil increases and then decreases. The shear strength of the Zn-contaminated red clay improved as the surrounding pressure increased.
Effect of Liquid Properties on the Characteristics of Collisions between Droplets and Solid Particles
Authors: Islamova Anastasia , Tkachenko Pavel , Shlegel Nikita , Kuznetsov Geniy
Published: October 2022

The characteristics of the collisions of droplets with solid particles (52,100 steel) were experimentally studied when varying the key liquid properties: viscosity (1–6.3 mPa·s), surface tension (72.69–36.1 mN/m) and interfacial (liquid-liquid) tension (3.41–42.57 mN/m). Distilled water, aqueous solutions of glycerol, surfactants and diesel emulsions were used. The experimental conditions corresponded to the following ranges: Weber number 5–450, Ohnesorge number 0.001–0.03, Reynolds number 0.1–1000, capillary number 0.01–0.3. Droplet-particle collision regimes (agglomeration, stretching separation) were identified and the characteristics of secondary liquid fragments (size, number) were determined. Droplet-particle interaction regime maps in the We(Oh) and Re(Ca) systems were constructed. Equations describing the transition boundaries between the droplet-particle interaction regimes were obtained. The equations take the form: We = a · Oh + c. For the conditions of the droplet-particle interaction, the relationship We = 2214 · Oh + 49.214 was obtained. For the interaction with a substrate: We = 1.0145 · Oh + 0.0049. The experimental results were compared with the characteristics of collisions of liquid droplets with each other. Differences in the characteristics of secondary atomization of droplets as a result of collisions were identified. Guidelines were provided for applying the research findings to the development of liquid droplet secondary atomization technologies in gas-vapor-droplet applications.
Clinical Applications of Nano-Hydroxyapatite in Dentistry
Authors: Izzetti Rossana , Gennai Stefano , Nisi Marco , Gulia Francesco , Miceli Marco , Giuca Maria Rita
Published: October 2022

Nano-hydroxyapatite (nano-HAp) is a biomaterial which is finding increasing application in dentistry due to its osteogenic properties and biocompatibility. The aim of the present study is to review the clinical applications of nano-HAp in dentistry. A literature search was performed in PubMeD and Scopus. In total, 154 articles were retrieved. Following title and abstract analysis, 122 articles were excluded. Further 6 articles were excluded through full-text analysis. The systematic review was conducted on 26 articles. In 3 studies, nano-HAp was employed for tissue remineralization, 8 studies applied nano-HAp for the treatment of dentin hypersensitivity, 2 studies evaluated the role of nano-HAp in orthodontics, 9 studies applied nano-HAp as a graft material, and 4 studies applied nano-HAp to periodontology and implantology. The available evidence supports the use of nano-HAp in the prevention of caries, as a desensitizing agent in the treatment of dentin hypersensitivity and as a graft material. It should be, however, highlighted that further research appears mandatory in assessing and validating the full potential of nano-HAp in clinical dentistry.
Position Detection of Doors and Windows Based on DSPP-YOLO
Authors: Zhang Tong , Li Jiaqi , Jiang Yilei , Zeng Mengqi , Pang Minghui
Published: October 2022

Autonomous exploration of autonomous mobile robots in unknown environments is a hot topic at present. Object detection is an important research direction in improving the autonomous capability of autonomous mobile robots in unknown environments. In object detection, doors and windows have many similar features and are difficult to distinguish. Therefore, improving the detection accuracy of doors and windows is helpful to improve the autonomous ability of autonomous mobile robots. Aiming at the problem of insufficient doors and windows detection accuracy caused by the large difference between the receptive fields of doors and windows, this paper proposes DSPP-YOLO (DenseNet SPP) algorithm. Firstly, on the basis of deepening the network addition, to prevent the loss of shallow location feature information, some residual blocks in YOLOV3 are improved to dense blocks by using the idea of DenseNet. Secondly, the spatial pyramid pooling (SPP) structure is fused into the YOLOV3 feature extraction network to realize multiscale receptive field fusion. Finally, K-means ++ algorithm is used to re-cluster the size of candidate boxes to reduce the error caused by candidate boxes. DSPP-YOLO realizes the position detection of doors and windows by an autonomous robot in an unknown, complex environment. This method is tested. Under the condition of the same data set, the detection accuracy of the DSPP-YOLO algorithm is 77.4% for doors and 38.1% for windows. Compared with YOLOV3 algorithm, the calculation consumption time of the DSPP-YOLO algorithm does not increase, and the detection accuracy of doors is improved by 3.3%, the detection accuracy of windows is improved by 8.8%, and the average accuracy of various types is improved by 6.05%.
Analysis of the Effect of Antenna Pointing Error Caused by Satellite Perturbation on Space Terahertz Communication
Authors: He Yuanzhi , Ma Chensheng
Published: October 2022

The terahertz frequency band has the advantages of having a large bandwidth, narrow beam, strong penetration, and high security, and is an important direction for the frequency expansion of next-generation satellite communications. Due to the narrow terahertz beam, the pointing error caused by satellite perturbation will affect the attenuation of the terahertz wave power, resulting in a decrease in the received power of the system and affecting the communication performance of the system. In order to accurately analyze the influence of pointing error caused by satellite perturbation on the performance of space terahertz communication system, based on satellite perturbation model and Gaussian channel model, this paper deduces the accurate analysis of signal power attenuation model without pointing error and with pointing error untie. The antenna pointing error in the real environment is simulated by using the TLE data of the actual satellite, and the influence of the pointing error on the space terahertz communication is analyzed. The results show that the antenna pointing error caused by satellite perturbation changes periodically with the operation of the satellite, which will cause great signal power attenuation, reduce the signal-to-noise ratio of the space terahertz communication system, and seriously affect the communication quality. In addition, the higher the frequency, the greater the impact on space terahertz communication, which needs to be solved through attitude control and antenna compensation.
The Use of Artificial Intelligence in Orthopedics: Applications and Limitations of Machine Learning in Diagnosis and Prediction
Authors: Innocenti Bernardo , Radyul Yanislav , Bori Edoardo
Published: October 2022

Over the last several years, the impact of Artificial Intelligence on the world and on society has been undeniable. More specifically, a subfield, known as Machine Learning (ML), is driving innovation in a vast variety of fields as it denotes the ability of a machine to identify relationships between data without explicit criteria, emulating a human-like type of learning. Over the last decade, research efforts have also been focused on orthopedics in order to provide help and assistance to surgeons and clinicians in their daily tasks. The purpose of this paper is to serve as a guide by presenting the most recent research and achievements in orthopedics concerning these new technologies, by exposing the main concepts and limitations of different applications, and tackling the main problems concerning both the field and the technology itself. The main ML techniques will be introduced and qualitatively explored, by considering the indexes that better identify the performance of the models; then, the main two applications will be addressed: diagnosis and prediction. Finally, a discussion about the limitations of the studies and technologies will be proposed.
“You Can Do This”: Working with the Artistic Legacy of El Lissitzky
Authors: Renders Willem Jan
Published: October 2022

The collection of the Van Abbemuseum in Eindhoven comprises works by some 800 modern and contemporary artists, and El Lissitzky is one of the most important among them. This special position for Lissitzky is not due simply to the number of his works in the collection. In addition, his oeuvre, ideas and artistic objectives correspond closely with the museum’s engagement with experimentation, radical creativity and public participation. As one of the most dynamic artists of his time, over the years Lissitzky has become more and more important to the museum. He was anything but a creator of static, self-contained works. His creativity was powerful and open to many, a mass of plans and projects bristling with life. Inspired by Lissitzky, the Van Abbemuseum was keen to make that verve and vitality tangible for today’s public. The primary way to do that was to research, show and discuss his original works, but in many cases it was possible to go one step further and reconstruct what was lost or finish what the artist had started. Also, Lissitzky’s works were a source of inspiration for a number of contemporary artists. In this article I will discuss how these works came to Eindhoven and give examples of how the Van Abbemuseum treated this artistic legacy in exhibitions, reconstructions, constructions and new artworks.
Interactions of Biosphere and Atmosphere within Longleaf Pine Restoration Areas
Authors: Chen Xiongwen , Willis John L.
Published: October 2022

Longleaf pine forests are economically and culturally valued ecosystems in the southeastern United States. Efforts to restore the longleaf pine ecosystem have risen dramatically over the past three decades. Longleaf pine restoration generally involves varying degrees of forest harvesting and frequent applications of prescribed fire. Thus, it is important to understand their interactions with the atmosphere on a large scale. In this study, we analyzed 14 parameters of aerosols, gasses, and energy from three areas with longleaf pine restoration (named Bladen in eastern NC, Escambia in southern AL and northern FL, and Kisatchie in central LA, USA) from 2000 to 2021 using multiple satellites. Averaged across the areas, the monthly aerosol optical depth at 483.5 nm was about 0.022, and the monthly aerosol single scattering albedo was 0.97. Black carbon column mass density averaged 7.46 × 10−7 kg cm−2 across these areas, but Kisatchie had a higher monthly dust column mass density (2.35 × 10−4 kg cm−2) than Bladen or Escambia. The monthly total column ozone and CO concentration averaged about 285 DU and 135 ppbv across the three areas. Monthly SO2 column mass density was significantly higher in Bladen (4.42 × 10−6 kg cm−2) than in Escambia and Kisatchie. The monthly surface albedo in Escambia (0.116) was significantly lower than in the other areas. The monthly total cloud area fraction averaged about 0.456 across the three areas. Sensible and latent heat net flux and Bowen ratios significantly differed among the three areas. Bowen ratio and total cloud area fraction were not significantly correlated. Net shortwave of the forest surface averaged about 182.62 W m−2 across the three areas. The monthly net longwave was much lower in Bladen (−90.46 W m−2) than in Escambia and Kisatchie. These results provide the baseline information on the spatial and temporal patterns of interactions between longleaf pine forests under restoration and the atmosphere and can be incorporated into models of climate change.
Features and Evolution of Autumn Weather Regimes in the Southeast China
Authors: Wang Yongdi , Sun Xinyu
Published: October 2022

Autumn is the transitional season when the atmospheric circulation pattern changes from summer to winter. The temperature and precipitation in Southeastern China in autumn are significantly influenced by the change in circulation patterns, and both show significant uniqueness. The clustering method can be used to observe the changes of circulation patterns in detail and to observe and analyze the transition from warm to cold seasons from a detailed view of the daily circulation pattern perspective. This method may have important research implications on how to study the generation and dissipation of extreme weather events. The Self-Organizing Maps (SOM) method is used to a 500 hPa geopotential height and 850 hPa wind and sea level pressure for 1981–2020 to identify the characteristic weather patterns (WTs) in autumn (September–November) over Southeastern China. Characteristics of the captured WTs are also analyzed in terms of the distribution characteristics of weather patterns, occurrence frequency, typical progression, precipitation and extreme precipitation (EP), temperature and extreme high temperature (EHT), and the relationship with atmospheric teleconnection. Nine WTs were identified in autumn, which represents a series of weather situations consisting of troughs and ridges. On this basis, these WTs were used to carry out the differentiation of seasonal differences between early and late autumn. The maximum mean and extreme precipitation occur in several early season patterns (WT1, WT2, WT4, and WT7). It is highly likely that extremely high temperatures occur in the WT1 and WT2 patterns. The most common progression between WTs is WT7−WT1−WT2−WT4 in the early season. This seasonality allows us to distinguish between early and late seasons based on daily weather types. A preliminary trend analysis suggests that patterns in the early season occur more frequently and last longer in the early season, and patterns in the late season occur less frequently and later. That is, the longer cool season pattern is shifting to the shorter warm season pattern. In addition, the persistence of both cool and warm patterns increased during 2001–2020 relative to 1981–2000, and the risk of both flooding and drought occurrence is on the rise.
Joint Contribution of Preceding Pacific SST and Yunnan-Guizhou Plateau Soil Moisture to September Precipitation over the Middle Reaches of the Yellow River
Authors: Jin Lijun , Liu Ge , Wei Xinchen , Zhang Ting , Feng Yuhan
Published: October 2022

The middle reaches of the Yellow River (MRYR) are an important base for agricultural and husbandry production and coal and coal-based power and chemical industries. Understanding the variability of autumn (especially September) precipitation over the MRYR region and the associated atmospheric circulation anomalies and precursory signals is of great importance for the prevention and mitigation of meteorological disasters during autumn rainy season. This study primarily explored precursory signals for September precipitation over the MRYR from the perspectives of sea surface temperature (SST) and soil moisture (SM) anomalies. The results reveal that the northward-shifted East Asian westerly jet (EAWJ) and the strengthened and westward-extended western Pacific subtropical high (WPSH) are responsible for more precipitation over the MRYR region. Further analyses show that the September MRYR precipitation is significantly related to the preceding July–August southern Pacific SST pattern (SPSP) and Yunnan-Guizhou Plateau (YGP) SM. The preceding SPSP anomaly, which reflects the La Niña/El Niño-like SST anomalies, can be maintained until September and plays an important role in modulating the September MRYR precipitation. Moreover, the above SST anomalies may adjust the SM anomalies in the YGP during July–August. The SM anomalies in The YGP persist from July–August to September and eventually affect the MRYR precipitation through exciting an anomalous vertical motion during September. The effect of the preceding SPSP anomaly on the September MRYR precipitation decreases when the SM effect is absent, which suggests that the YGP SM anomalies act as a bridge linking the preceding Pacific SST anomalies and the ensuing September MRYR precipitation. This study discloses the joint contribution of the preceding Pacific SST and YGP SM anomalies to the September MRYR precipitation and may shed new light on the short-term prediction of autumn precipitation over the MRYR.
Review of the Observed Energy Flow in the Earth System
Authors: Liu Chunlei , Chen Ni , Long Jingchao , Cao Ning , Liao Xiaoqing , Yang Yazhu , Ou Niansen , Jin Liang , Zheng Rong , Yang Ke , Su Qianye
Published: October 2022

The energy budget imbalance at the top of the atmosphere (TOA) and the energy flow in the Earth’s system plays an essential role in climate change over the global and regional scales. Under the constraint of observations, the radiative fluxes at TOA have been reconstructed prior to CERES (Clouds and the Earth’s Radiant Energy System) between 1985 and 2000. The total atmospheric energy divergence has been mass corrected based on ERA5 (the fifth generation ECMWF ReAnalysis) atmospheric reanalysis by a newly developed method considering the enthalpy removing of the atmospheric water vapor, which avoids inconsistencies due to the residual lateral total mass flux divergence in the atmosphere, ensuring the balances of the freshwater fluxes at the surface. The net surface energy flux (Fs) has been estimated using the residual method based on energy conservation, which is the difference between the net TOA radiative flux and the atmospheric energy tendency and divergence. The Fs is then verified directly and indirectly with observations, and results show that the estimated Fs in North Atlantic is superior to those from model simulations. This paper gives a brief review of the progress in the estimation of the observed energy flow in the Earth system, discusses some caveats of the existing method, and provides some suggestions for the improvements of the aforementioned data sets.
Cyclonic and Anticyclonic Asymmetry of Reef and Atoll Wakes in the Xisha Archipelago
Authors: Zhao Zhuangming , Yan Yu , Qi Shibin , Liu Shuaishuai , Chen Zhonghan , Yang Jing
Published: October 2022

A high-resolution (∼500 m) numerical model was used to study the reef and atoll wakes in the Xisha Archipelago (XA) during 2009. Statistical analyses of simulation data indicated strong cyclonic dominance in the mixing layer (above ∼35 m) and weak anticyclonic dominance in the subsurface layer (35∼160 m) for both eddies and filaments in the XA. The intrinsic dynamical properties of the flow, such as the vertical stratification and velocity magnitude, and the terrain of reefs and atolls had a significant effect on the asymmetry. Without considering the existence of reefs and atolls, the “background cyclonic dominance” generated under local planetary rotation (f≈4.1×10−5 s−1) and vertical stratification (with mean Brunt–Väisälä frequency N = 0.02 s−1 at 75 m) was stronger for filaments than eddies in the upper layer from 0∼200 m, and the larger vorticity amplitude in the cyclonic filaments could greatly enhance the cyclonic wake eddies. Furthermore, inertial–centrifugal instability induced selective destabilization of anticyclonic wake eddies in different water layers. As the Rossby number (Ro) and core vorticity (Burger number, Bu) decreased (increased) with the water depth, a more stable state was achieved for the anticyclonic wake eddies in the deeper layer. The stratification and slipping reefs and atolls also led to vertical decoupled shedding, which intensified the asymmetry.
Temporal and Spatial Distribution Characteristics of Drought and Its Influence on Vegetation Change in Xilin Gol, China
Authors: Chen Zexun , Wang Wenjun , Wu Yingjie , Yin Hang , Li Wei , Zhao Shuixia
Published: October 2022

Drought hinders economic and social growth in many areas of China, especially in livestock-dominated Xilin Gol League in Inner Mongolia. Most studies exclusively utilize rainfall to measure drought. To clarify the spatial and temporal distribution characteristics and evolution rules of meteorological drought, monthly observation data from nine meteorological stations in Xilin Gol were used to calculate the (effective drought index, EDI). We studied the spatiotemporal pattern of drought and its influence on vegetation in Xilin Gol using the Mann–Kendall test, (empirical orthogonal function, EOF) decomposition, and quantitative representation. (1) The annual average EDI declined by 0.029/10a, and Xilin Gol experienced an average of 0.5 drought occurrences every year. (2) A normal incidence in Xilin Gol is 67.17–72.65%, and that of severe drought is 0.02–0.99%. (3) Xilin Gol’s drought intensity is mostly concentrated in the central, northeast, and southwest regions, especially southwest and central. (4) The first two principal feature vectors in Xilin Gol contributed 52.75% and 14.38% to the variance. (5) The average (normalized differential vegetation index, NDVI )of desert, typical, and meadow steppe increased, especially in typical steppe (0.034/10a). (6) In Xilin Gol, the NDVI–EDI correlation coefficient ranges from −0.642 to 0.888, with an average of 0.392. Only 1.7% of the areas are adversely linked.
The Seismo-Ionospheric Disturbances before the 9 June 2022 Maerkang Ms6.0 Earthquake Swarm
Authors: Liu Jiang , Zhang Xuemin , Wu Weiwei , Chen Cong , Wang Mingming , Yang Muping , Guo Yufan , Wang Jun
Published: October 2022

Based on the multi-data of the global ionospheric map (GIM), ionospheric total electron content (TEC) inversed from GPS observations, the critical frequency of the F2 layer (fOF2) from the ionosonde, electron density (Ne), electron temperature (Te), and He+ and O+ densities detected by the China Seismo-Electromagnetic Satellite (CSES), the temporal and spatial characteristics of ionospheric multi-parameter perturbations were analyzed around the Maerkang Ms6.0 earthquake swarm on 9 June 2022. The results showed that the seismo-ionospheric disturbances were observed during 2–4 June around the epicenter under quiet solar-geomagnetic conditions. All parameters we studied were characterized by synchronous changes and negative anomalies, with a better consistency between ionospheric ground-based and satellite observations. The negative ionospheric anomalies for all parameters appeared 5–7 days before the Maerkang Ms6.0 earthquake swarm can be considered as significant signals of upcoming main shock. The seismo-ionospheric coupling mechanism may be a combination of two coupling channels: an overlapped DC electric field and an acoustic gravity wave, as described by the lithosphere–atmosphere–ionosphere coupling (LAIC). In addition, in order to make the investigations still more convincing, we completed a statistical analysis for the ionospheric anomalies of earthquakes over Ms6.0 in the study area (20°~40° N, 92°~112° E) from 1 January 2019 to 1 July 2022. The nine seismic events reveal that most strong earthquakes are preceded by obvious synchronous anomalies from ground-based and satellite ionospheric observations. The anomalous disturbances generally appear 1–15 days before the earthquakes, and the continuity and reliability of ground-based ionospheric anomaly detection are relatively high. Based on the integrated ionospheric satellite–ground observations, a cross-validation analysis can effectively improve the confidence level of anomaly identification and reduce the frequency of false anomalies.
Study on the Complexity Reduction of Observed Sequences Based on Different Sampling Methods: A Case of Wind Speed Data
Authors: Huai Xiaowei , Yan Pengcheng , Li Li , Cai Zelin , Xu Xunjian , Hu Xiaohui
Published: October 2022

Many studies have confirmed that the complexity of a time sequence is closely related to its predictability, but few studies have proposed methods to reduce the time sequence complexity, which is the key to improving its predictability. This study analyzes the complexity reduction method of observed time sequences based on wind speed data. Five sampling methods, namely the random method, average method, sequential method, max method and min method, are used to obtain a new time sequence with a low resolution from a high resolution time sequence. The ideal time sequences constructed by mathematical functions and the observed wind speed time sequences are studied. The results show that the complexity of ideal time series of periodic sequences, chaotic sequences and random sequences increases in turn, and the complexity is expressed by the approximate entropy (ApEn) exponent. Furthermore, the complexity of the observed wind speed is closer to the complexity of a random sequence, which indicates that the wind speed sequence is not easy to predict. In addition, the complexity of sub-time series change with different sampling methods. The complexity of sub-time series obtained by the average method is the lowest, which indicates that the average method can reduce the complexity of observed data effectively. Therefore, the complexity of sub-time series sampled from the high-resolution wind speed data is reduced by using the average method. The method that can reduce the complexity of wind speed substantially will help to choose the appropriate wind speed data, thus improving the predictability.
Sensitivity of Chlorophyll Variability to Specific Growth Rate of Phytoplankton Equation over the Yangtze River Estuary in a Physical–Biogeochemical Model
Authors: Wu Qiong , Wang Xiaochun , Xiu Peng , Chai Fei , Chen Zhongxiao
Published: October 2022

In addition to nutrients and light, temperature plays a crucial role in marine biogeochemical processes. In this study, the sensitivity of the growth rate of phytoplankton to temperature was systematically studied by using a two-level nested physical–biogeochemical coupled model for the Yangtze River estuary of the East China Sea. The physical component of the coupled model is configured from the Regional Ocean Modeling System (ROMS) with the highest horizontal resolution of 3 km. The biogeochemical component of the coupled model is based on the carbon, silicon and nitrogen ecosystem model (CoSiNE). Five specific growth rate of phytoplankton equations with different relation to temperature were tested with the objective of reproducing the temporal evolution of chlorophyll concentration as observed by SeaWiFS. Our results indicate that the specific growth rate of phytoplankton equation which is from Geider’s work, reaches a maximum at 22 °C and remains constant with higher temperature, can reproduce the seasonal variation of chlorophyll very well, and may be suitable for application in the physical–biogeochemical coupled model (ROMS-CoSiNE) of the Yangtze River estuary.
Climate Change Impacts on Soil Erosion and Sediment Delivery to German Federal Waterways: A Case Study of the Elbe Basin
Authors: Uber Magdalena , Rössler Ole , Astor Birgit , Hoffmann Thomas , Van Oost Kristof , Hillebrand Gudrun
Published: October 2022

Climate change is an important driver of soil erosion and sediment delivery to water bodies. We use observation data from 193 locations in the Elbe River basin as well as spatially distributed erosion rates and sediment delivery simulated in the WaTEM/SEDEM to identify current erosion hotspots and to assess the impact of climate change on future erosion and sediment delivery. We further quantified the uncertainty of the modelling approach by using an ensemble of 21 combinations of global and regional climate models, different emission scenarios and stochastic erosion modelling. Erosion rates are highest on hilly arable land in the central part of the basin as well as in the northeast of Bohemia. Despite considerable differences between climate models and emission scenarios and considerable uncertainties of the erosion model, a future increase in soil erosion and sediment delivery is highly likely. Using the median of climate models and behavioral erosion models, this increase can be up to 14% higher in the far future (2071–2100) than in the reference period (1971–2000) using RCP 8.5. The increase is highest in the Czech part of the basin.