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Millimeter-wave channel modeling is the basis of fifth-generation (5G) communication network design and applications. In urban microcellular environments, the roughness of wall surfaces can be comparable to the wavelengths of millimeter waves, resulting in walls that cannot be considered as smooth surfaces. Therefore, channel modeling methods based on only traditional three-dimensional ray tracing (RT) or the three-dimensional parabolic equation (PE) result in the limited computational accuracy of millimeter-wave channel models for urban environments. Based on the scattering theory of a rough surface and the typical scattering characteristics of a millimeter wave, the end field of the three-dimensional vector PE is regarded as the initial field of three-dimensional RT. Moreover, the number of scattered rays and scattering angles are introduced. Finally, a three-dimensional fully polarized millimeter-wave hybrid propagation channel model (3DFPHPCM) is proposed. The proposed model improves the computational accuracy of a single deterministic model. Millimeter-wave channel measurements in non-line-of-sight (NLOS) environments were carried out to verify and optimize the proposed 3DFPHPCM. The results show that the root mean square error (RMSE) and mean absolute error (MAE) of the proposed 3DFPHPCM are both minimized when compared to three-dimensional RT or the three-dimensional PE, which indicates that the proposed 3DFPHPCM has higher computational accuracy. Moreover, its runtime is the shortest among the methods. The results presented herein provide technical support for the layout of base stations. [ABSTRACT FROM AUTHOR]

This paper aims to improve a small-scale object detection model to achieve detection accuracy matching or even surpassing that of complex models. Efforts are made in the module design phase to minimize parameter count as much as possible, thereby providing the potential for rapid detection of maritime targets. Here, this paper introduces an innovative Anchor-Free-based Multi-Scale Feature Fusion Network (AFMSFFNet), which improves the problems of missed detection and false positives, particularly in inshore or small target scenarios. Leveraging the YOLOX tiny as the foundational architecture, our proposed AFMSFFNet incorporates a novel Adaptive Bidirectional Fusion Pyramid Network (AB-FPN) for efficient multi-scale feature fusion, enhancing the saliency representation of targets and reducing interference from complex backgrounds. Simultaneously, the designed Multi-Scale Global Attention Detection Head (MGAHead) utilizes a larger receptive field to learn object features, generating high-quality reconstructed features for enhanced semantic information integration. Extensive experiments conducted on publicly available Synthetic Aperture Radar (SAR) image ship datasets demonstrate that AFMSFFNet outperforms the traditional baseline models in detection performance. The results indicate an improvement of 2.32% in detection accuracy compared to the YOLOX tiny model. Additionally, AFMSFFNet achieves a Frames Per Second (FPS) of 78.26 in SSDD, showcasing superior efficiency compared to the well-established performance networks, such as faster R-CNN and CenterNet, with efficiency improvement ranging from 4.7 to 6.7 times. This research provides a valuable solution for efficient ship detection in complex backgrounds, demonstrating the efficacy of AFMSFFNet through quantitative improvements in accuracy and efficiency compared to existing models. [ABSTRACT FROM AUTHOR]

PURPOSE Although the cost and complexity of managing diabetes is increasing around the world, placing greater burden on patients and their families, the cost of drug regimens prescribed to Chinese patients has not been evaluated. This study was conducted to evaluate the temporal changes in the costs and drugs used for people with diabetes. METHODS Patients enrolled in Beijing Medical Insurance with outpatient medical records from 2016 through 2018 were included in this study. The outcomes of interest were: (1) the number of outpatient medications, (2) the number of comorbidities diagnosed, (3) the estimated annual cost of the outpatient drug regimen, (4) the drug therapy strategies used for diabetic patients, and (5) the most commonly prescribed classes of drugs. RESULTS Over the 3-year period, there was a significant decrease (9.0%, P CONCLUSION This is the first large-scale cost analysis of the medical management of diabetes since the implementation of medical insurance in China. Despite the increasing availability of newer, more expensive diabetes drugs, there was a significant reduction in the number of diabetes medications used, that may be due to a more rational approach to optimizing metabolic targets. Key words: diabetes mellitus; drug costs; drug therapy; medicare Submitted August 8, 2020; submitted, revised, December 24, 2020; accepted January 5, 2021., INTRODUCTION Diabetes is one of the 4 major noncommunicable diseases (1) and is a cause of premature death and disability. International Diabetes Federation data show that 415 million individuals worldwide [...]

Alumina (Al2O3) particles, the primary combustion products of solid rockets, can accumulate in the stratosphere, changing the global radiative balance. These Al2O3 particles were usually treated as homogeneous spheres. However, they contain impurities and may form clusters during the combustion process. Models representing Al-containing and C-containing Al2O3 clusters were developed, denoted as Al2O3 shell model (ASM) and Al2O3 core model (ACM), respectively. The superposition T-matrix method (STMM) was applied to examine their optical characteristics. Subsequently, a method to obtain the top-of-atmosphere flux was proposed by integrating the models with the moderate resolution atmospheric transmission code (MODTRAN). With the addition of Al/C, the absorption cross-section enhances by several orders of magnitude at 0.55 μm and increases slightly at 10 μm. The equivalent sphere models will weaken their scattering ability. A 4Tg mass burden of Al2O3 produces radiative forcing of −0.439 Wm−2. However, the addition of Al and C reduces the forcing by up to 15% and 12%, respectively. In summary, the optical characteristics and radiative forcing of Al2O3 clusters are sensitive to Al/C and morphology models. While our findings are impacted by various uncertainties, they contribute valuable insights into the radiative forcing of Al2O3 particles, potential climatic changes by space activities. [ABSTRACT FROM AUTHOR]

The aim of this study is to accurately extract the dielectric parameters of building materials through nondestructive measurement methods. The ultrawideband (UWB) measurement system is used to capture echoes from marble targets in the frequency range of 2.5–15 GHz, and the reflection coefficient is derived using a time window separation technique. By combining the particle swarm optimization (PSO) algorithm, the dielectric parameters of the marble targets are successfully inverted. Research results show that the relative dielectric constant extracted under three different incident angle conditions ranges from 5.370 to 5.545, and the conductivity ranges from 0.00429 to 0.00515 S/m. The root mean square error (RMSE) between the theoretically calculated reflection coefficient and the measured reflection coefficient ranges from 0.013 to 0.025, while the RMSE ranges from 0.047 to 0.066 if the dielectric parameters recommended by ITU‐R P.2040‐3 are used, thus confirming the accuracy and reliability of the proposed method for dielectric parameters extraction. [ABSTRACT FROM AUTHOR]

During reentry, the high temperatures experienced by near-space hypersonic vehicles result in surface ablation, generating ablative particles. These particles become part of a plasma, commonly referred to as a "dusty plasma sheath" in radar remote sensing. The dusty plasma model, integral in radar studies, involves extensive charge and dynamic interactions among dust particles. Previous derivations assumed that the dust particle radius significantly surpassed the Debye radius, leading to the neglect of dust radius effects. This study, however, explores scenarios where the dust particle radius is not markedly smaller than the Debye radius, thereby deducing the charging process of dusty plasma. The derived equations encompass the Debye radius, charging process, surface potential, and charging frequency, particularly considering larger dust particle radii. Comparative analysis of the dusty plasma model, both before and after modification, reveals improvements when dust particles approach or exceed the Debye length. In essence, our study provides essential equations for understanding dusty plasma under realistic conditions, offering potential advancements in predicting electromagnetic properties and behaviors, especially in scenarios where dust particles closely align with or surpass the Debye radius. [ABSTRACT FROM AUTHOR]