Search Results (240)

Bucklew and Wise (1982) showed that the quantization dimension of an absolutely continuous probability measure on a given Euclidean space is constant and equals the Euclidean dimension of the space, and the quantization coefficient exists as a finite positive number. By giving different examples, in this paper, we have shown that the quantization coefficients for absolutely continuous probability measures defined on the same Euclidean space can be different. We have taken uniform distribution as a prototype of an absolutely continuous probability measure. In addition, we have also calculated the conditional optimal sets of n-points and the nth conditional quantization errors for the uniform distributions in constrained and unconstrained scenarios. Full article

Urban green spaces (UGS) are essential for residents’ well-being, environmental quality, and social cohesion. However, previous studies have typically employed undifferentiated analytical frameworks, overlooking UGS types and failing to adequately measure the structural disparities of different UGS types within residents’ walking distance. To address this, this study integrates Gaussian Two-Step Floating Catchment Area models, Simpson’s index, and the Gini coefficient to construct an accessibility–diversity–equality assessment framework for UGS. This study conducted an analysis of accessibility, diversity, and equity for various types of UGSs under pedestrian conditions, using the high-density city of Shenzhen, China as a case study. Results reveal high inequality in accessibility to most UGS types within 15 min to 30 min walking range, except residential green spaces, which show moderate-high inequality (Gini coefficient: 0.4–0.6). Encouragingly, UGS diversity performs well, with over 80% of residents able to access three or more UGS types within walking distance. These findings highlight the heterogeneous UGS supply and provide actionable insights for optimizing green space allocation to support healthy urban development. Full article

Due to the high-precision angle measurement performance, the monopulse technique plays a key role in fields such as remote sensing and space surveillance. The accuracy of monopulse angle measurement depends on the received amplitude and phase information, which is sensitive to the polarization component. Previous research has demonstrated that the performance of monopulse radar equipped with a parabolic antenna suffers from the cross-polarization component. However, it is not clear whether phased arrays (PAs) with higher degrees of freedom will also be affected by the cross-polarization component, and the parameter tolerance for performance degradation remains uncertain. In this paper, we establish a mathematical model of monopulse angle measurement in PA radar, which provides a comprehensive consideration of the cross-polarization component. Then, the received amplitude and phase patterns of PA radar are analyzed, and the theoretical angle errors caused by the cross-polarization jamming are derived. The experiments are conducted based on the measured amplitude-phase patterns of both co-polarization and cross-polarization. Experimental results are consistent with the theoretical analysis: the angle errors caused by cross-polarization jamming can reach half of the beamwidth in both azimuth and elevation dimensions, provided that the power of the cross-polarization and co-polarization components at the receiver is equal. Full article

This paper presents an enhanced circularly polarized (CP) all-textile antenna using a metasurface (MS) and slot-patterned ground (SPG) for 5.8 GHz industry, scientific, and medical (ISM)-band applications in off-body communications. The 3 × 3 MS, capable of converting the incident wave into an orthogonal direction with equal magnitude and a 90° phase difference, converts the linearly polarized (LP) wave, radiated from the fundamental radiator with a corner-truncated slot square-patch configuration, into being CP. The SPG, consisting of periodic slots with two different sizes of corner-truncated slots, redistributes the surface current on the ground plane, enhancing the axial ratio bandwidth (ARBW) of the proposed antenna. The novel combination of MS and SPG not only enables the generation and enhancement of CP characteristics but also significantly improves the impedance bandwidth (IBW), gain, and radiation efficiency by introducing additional surface wave resonances. The proposed antenna is composed of a conductive textile and a felt substrate, offering comfort and flexibility for applications where the antenna is placed in close proximity to the human body. The proposed antenna is simulated under bending in various directions, showing exceptionally similar characteristics to a flat condition. The proposed antenna is fabricated and is then verified by measurements in both free space and a human body environment. The measured IBW is 36.3%, while the ARBW is 18%. The measured gain and radiation efficiency are 6.39 dBic and 64.7%, respectively. The specific absorption rate (SAR) is simulated, and the results satisfy both US and EU safety standards. Full article

Background: The intercondylar notch (IN) houses the central ligaments of the knee joint, namely the anterior and posterior cruciate ligaments (ACL and PCL) as well as the anterior and posterior meniscofemoral ligaments (aMFL and pMFL). As not only the available intercondylar space directly influences the encased ligaments, but also the ligaments themselves may influence each other, the purpose of this study was to evaluate the influence of osteoarthritis on central ligament morphology. Methods: Imaging data from the osteoarthritis initiative was used to assess 415 randomly selected patients, equally distributed across five groups based on osteoarthritis severity using the Kellgren and Lawrence classification. MRI scans were used to measure ligament structures in the coronal, axial and sagittal planes. The ACL was evaluated and classified into healthy, pathologic and ruptured. The relationship between osteoarthritis severity and the shape of the IN (A-shape, inverse-U-shape and Ω-shape) was analyzed in relation to ligament morphometrics and ACL condition. Results: The morphology of the ligaments is directly influenced by the development of osteoarthritis. In particular, the Ω-shape, which is associated with severe-grade osteoarthritis, is a risk factor for the development of ACL rupture (p < 0.001). But also, the condition of the ACL influenced the morphometrics of the posterior ligaments, and the PCL as well as the MFLs influenced each other. Conclusions: Statistically significant morphological changes to the encased ligaments in the intercondylar space in osteoarthritis were reported. In particular, the ACL shows a higher risk for pathological changes during ongoing joint degeneration due to osteoarthritis. The other evaluated ligaments—MFLs and PCL—are influenced by the condition of the osseous structures and the shape of the IN as well as by the condition and continuity of the ACL. Full article

Background/Objectives: This cross-sectional analytical study investigated the relationship between the craniofacial morphology, condylar displacement, and degenerative changes in the temporomandibular joints (TMJs) in adult patients with class II skeletal malocclusion. To compare cephalometric variables, joint space dimensions, and centric slide measurements between patients with and without CBCT-confirmed TMJ degenerative alterations. Methods: Sixty adults with class II malocclusion were divided into two equal groups (n = 30) based on the presence or absence of TMJ degenerative changes on CBCT. Joint spaces were measured, condylar displacement was evaluated using a condylar position indicator (CPI), and cephalometric analysis was performed in both maximal intercuspation and centric relation. Statistical comparisons were performed using t-tests, chi-squared tests, and Pearson’s correlation analysis. Significance was set at p < 0.05. Results: Patients with degenerative TMJ changes exhibited significantly greater overjet (p = 0.0001) and a trend toward increased ANB angles (p = 0.055). The superior joint space was reduced on the right side (p = 0.031). Condylar displacements ≥ 2 mm were more frequent in the affected group and correlated with sagittal cephalometric discrepancies (45% vs. 24% in controls). Conclusions: Aggravated skeletal class II malocclusion with increased overjet could be associated with TMJ degenerative changes. CR-based cephalometry and CBCT evaluation may aid in diagnostic assessment, but longitudinal studies are needed to confirm the clinical relevance. Full article

Neighbourhood variation in socioeconomic deprivation is recognised as a small but meaningful determinant of adolescent mental health, yet the mechanisms through which the effects operate remain poorly understood. This study used #BeeWell survey data collected from adolescents in Greater Manchester (England) in 2021–2023 (life satisfaction: N = 27,009; emotional difficulties: N = 26,461). Through Latent Growth Mixture Modelling, we identified four non-linear trajectories of life satisfaction (Consistently High (71.0%), Improving (8.7%), Deteriorating (6.3%), and Consistently Low (13.9%); entropy = 0.66) and three non-linear trajectories of emotional difficulties (Low/Lessening (53.7%), Sub-Clinical (38.3%), and Elevated/Worsening (8.0%); entropy = 0.61). Using a multi-level mediation framework we assessed (1) whether neighbourhood deprivation predicted trajectory class membership and (2) the extent to which effects of deprivation operate through aspects of Community Wellbeing, as measured by the Co-op Community Wellbeing Index (CWI). Greater deprivation increased the odds of following Deteriorating (OR = 1.081, [1.023, 1.12]) and Consistently Low (OR = 1.084, [1.051, 1.119]) life satisfaction trajectories and reduced the odds of following a Sub-Clinical emotional difficulties trajectory (OR = 0.975, [0.954, 0.996]). Mediation analyses revealed that the effects of deprivation on Consistently Low life satisfaction partially operate through Equality (ab = 0.016, [0.002, 0.029]) and Housing, Space, and Environment (ab = −0.026, [−0.046, −0.006]). Further indirect effects were observed for Housing, Space, and Environment, which reduced likelihood of Sub-Clinical emotional difficulties for those living in deprived neighbourhoods (ab = −0.026, [−0.045, −0.008]). The findings highlight the distinct effects of neighbourhood deprivation on affective and evaluative domains of adolescent mental health and the protective effect of housing and related environmental factors in disadvantaged contexts, advancing our understanding of the mechanisms underpinning neighbourhood effects on dual-state adolescent mental health. Full article

The uncontrolled urbanization of Brazilian cities accentuates the imbalance between population demands and urban space planning. The integrated management of human and technological resources constitutes a fundamental governance strategy for the proposition of sustainable and effective responses to the challenges faced by cities. To generate references to public management, the objective of this research was to develop a management tool to verify the maturity level of Brazilian cities for smart city actions. A performance measurement system (PMS) organized smart city actions into 11 thematic areas, quantitatively measuring smart city actions in a down–top structure since the indicators and metrics are described in a standardized scale to obtain the general maturity index (GMI). The PMS was implemented in the city of Santa Maria/Brazil, where its GMI equal to 43.72% indicated a currently intermediate maturity level of smart city actions, mainly related to the low performance in the thematic areas of mobility, coexistence and reciprocity, and security and protection. To improve the current performance, five incremental actions were proposed, contemplating the key performance indicators “Public roads”, “Multipurpose lanes”, “Public accessibility”, “Accessibility signage”, and “Monitoring”, projecting a GMI equal to 49.75% and 55.78%, respectively, for an intermediate and an advanced maturity level scenario. Full article

In this work, we explore the optimization of 3D Electrical Resistivity Tomography (ERT) measurement protocols for a 3D borehole grid configuration. Currently, there is no widely accepted standard measurement scheme for such setups. The use of numerous electrodes and the possibility of cross-borehole configurations lead to an extremely large number of potential electrode combinations. However, not all these combinations contribute significantly to the final resistivity model, and a complete measurement cycle requires substantial time to perform. This becomes particularly problematic in dynamic subsurface conditions, where changes may occur during data acquisition. In such cases, the measurements collected within a single cycle may reflect different subsurface states. Conversely, attempting to shorten acquisition time can result in too few measurements to resolve the subsurface structure at high resolution. Furthermore, most existing approaches assume a uniform half-space model and treat all measurements equally, failing to prioritize those that are most sensitive to actual subsurface changes. To address these challenges, we propose a 3D measurement optimization approach that yields an efficient acquisition scheme. This method produces inversion results comparable to those obtained from much larger datasets while reducing both measurement and processing requirements. Our optimization is based on a sensitivity-driven selection algorithm that accounts for the real subsurface structure rather than assuming a generic half-space. The proposed methodology is validated using synthetic data and tested with experimental data obtained from a laboratory tank setup. These experimental measurements were used to monitor permeation grouting; a technique applied to reduce permeability and/or increase the strength of granular soils through targeted injection. Full article

Analyzing the population’s access to ecosystem services offered by urban greening constitutes a measure of environmental justice, as it directly affects the quality of life and health of the population living in cities. This article is committed to proposing a geoenvironmental model in a geographic information system (GIS), envisaged to estimate the share of urban forests and green spaces in territorial planning units (TPUs), corresponding to neighborhoods of a pilot city, using high-spatial-resolution images of the China–Brazil Earth Resources Satellite (CBERS-4A) and the normalized difference vegetation index (NDVI). These data were combined by means of a Boolean analysis with social vulnerability indicators assessed from census data related to income, education, housing, and sanitation. This model ultimately aims to identify priority areas for urban afforestation in the context of environmental justice and is thus targeted to improve the inhabitants’ quality of life. The municipality of Goiânia, the capital of Goiás state, located in the Brazilian Central–West Region, was chosen as the study area for this experiment. Goiânia presents 19.5% of its urban territory (82.36 km²) covered by vegetation. The analyses indicate an inequity in the distribution of urban forest patches and green areas in this town, where 7.8% of the total TPUs have low priority, 28.2% have moderate to low priority, 42.2% have moderate to high priority, and 21.8% have high priority for urban afforestation. This urban greening imbalance is particularly observed in its most urbanized central nuclei, associated with a peripheralization of social vulnerability. These findings are meant to support initiatives towards sound territorial planning processes designed to promote more sustainable and equal development to ensure environmental justice and combat climate change. Full article

Background/Objectives: The pubic symphysis is formed by the fusion of the right and left pubic bones. The metrics, such as breadth, length, and depth, increase during pregnancy and can be measured and analyzed using standard sonography. Obstetricians require clear and consistent criteria for standard sonography evaluation. Methods: Sonographic examinations were performed on a cohort of 225 pregnant women, aged between 23 and 41 years, as part of a prospective observational study. The parameters measured included pubic symphysis entry middle width, intertubercular distance, pubic symphysis width, and pubic symphysis depth. Results: The width of the pubic symphysis exhibited the greatest consistency, measuring between 2.2 and 11.3 mm, whereas the depth displayed the highest variability, ranging from 5.4 to 22.6 mm. The measurements most correlated with fetal weight included pubic symphysis entry width (6.5 ± 3.4 mm; p ˂ 0.001), pubic symphysis width (6.4 ± 2.9 mm; p ˂ 0.001), and depth (14.8 ± 4.8 mm; p = 0.03). The intertubercular distance exhibited the strongest correlation with maternal age (15.1 ± 5.4 mm; p = 0.03). In contrast, pubic symphysis entry width (6.4 ± 3.3 mm; p = 0.02; 6.4 ± 3.4 mm; p ˂ 0.001) and pubic symphysis width (6.3 ± 2.6 mm; p = 0.01; 6.3 ± 2.6; p ˂ 0.001) demonstrated stronger associations with maternal weight and weight gained during pregnancy, respectively. In the singular pregnancy group, the width of the pubic symphysis exhibited significant correlations with fetal weight categories: under or equal to 1000 g (4.56 ± 1.5 mm; p = 0.02), 1001–2000 g (5.51 ± 2.6 mm; p = 0.02), and more than 3000 g (7.3 ± 3.9 mm; p = 0.02). Pubic symphysis entry width is significantly correlated with fetal weight in the range of 1001–2000 g (5.5 ± 3 mm; p = 0.02) and fetal weight exceeding 3000 g (7.4 ± 3.9 mm; p = 0.02). In singular pregnancies, statistically significant differences were noted in intertubercular distance (15.9 ± 7.2 mm vs. 13.4 ± 6.2 mm; p = 0.03) when comparing fetuses weighing 2000 g or less between nulliparous and multiparous women. Conclusions: Fetal and maternal weight were the primary parameters that were positively correlated with these measurements. The term ‘pubic symphysis entry’ is proposed to describe a trapezoidal space situated superior to the pubic symphysis disc, delineated by an imaginary line connecting the bilateral pubic tubercles. Full article

We investigated the algorithms and physical models currently applied to remote sensing of the mesosphere and lower thermosphere (MLT) using space-based observations of the CO₂ 15 µm emission. We show that the measured 15 µm radiation constrains the population of excited CO₂ vibrational levels and the 15 µm radiative flux divergence in the MLT, but not the 15 µm cooling. Moreover, the models of the non-local thermodynamic (non-LTE) excitation of CO₂ in the MLT contradict the laboratory studies of this excitation. We present a new model of the non-LTE in CO₂ that is both consistent with the observed CO₂ 15 µm radiation and provides the CO₂ cooling of the MLT, which aligns with the laboratory-measured rate coefficient $k^O$ of the CO₂ vibrational excitation by collisions with O(³P) atoms. Its application shows that the current non-LTE models dramatically overestimate this cooling. Even for the low laboratory-confirmed rate coefficient of the CO₂-O(³P) excitation, $k^O=1.5\times {10}^{-12}$ ${\mathrm{s}}^{-1}$${\mathrm{cm}}^{-3}$, excess cooling is equal or higher than the true cooling, reaches a value of 10 K/day, and is maximized in the mesosphere region around 100 km—a region which is very sensitive to any changes in the heat balance. For $k^O=3.0\times {10}^{-12}$ ${\mathrm{s}}^{-1}$${\mathrm{cm}}^{-3}$, which is currently used in the general circulation models of the MLT, excess cooling reaches 25–30 K/day. The results of this study contradict the widely held belief that the 15 µm CO₂ emission is the primary cooling mechanism of the middle and upper atmospheres of Earth, Venus, and Mars. A significant reduction in 15 µm cooling will have a major impact on both the modeling of the current MLT and the estimation of its future changes due to increasing CO₂. It also strongly influences the interpretation of MLT 15 µm emission observations and provides new insights into the role of this emission in the middle and upper atmospheres of Mars, Venus, and other extraterrestrial planets. Full article

This paper investigates various estimation methods for the parameters of the unit Lindley distribution (U-LD) under both ranked set sampling (RSS) and simple random sampling (SRS) designs. The distribution parameters are estimated using the maximum likelihood estimation, ordinary least squares, weighted least squares, maximum product of spacings, minimum spacing absolute distance, minimum spacing absolute log-distance, minimum spacing square distance, minimum spacing square log-distance, linear-exponential, Anderson–Darling (AD), right-tail AD, left-tail AD, left-tail second-order, Cramér–von Mises, and Kolmogorov–Smirnov. A comprehensive simulation study is conducted to assess the performance of these estimators, ensuring an equal number of measuring units across both designs. Additionally, two real datasets of items failure time and COVID-19 are analyzed to illustrate the practical applicability of the proposed estimation methods. The findings reveal that RSS-based estimators consistently outperform their SRS counterparts in terms of mean squared error, bias, and efficiency across all estimation techniques considered. These results highlight the advantages of using RSS in parameter estimation for the U-LD distribution, making it a preferable choice for improved statistical inference. Full article

This study aims to present a low-cost, non-destructive microwave sensor implementation to monitor the real-time moisture content of rubber wood in industrial dehydration processes. The proposed sensor is based on the free-space measurement technique with magnitudes S₁₁ and S₂₁ only. The novelties of this study consist of the natural frequency determination of rubber wood and the design of a sensor system using devices available on the market with reasonable cost performance. The natural frequency was determined using a simulation and was equal to 1.25 GHz. It specified the sensor system design and device selection. The designed system was initially verified by measuring the moisture content of rubber wood in the laboratory. The measured S₁₁ and S₂₁ voltages correlating with moisture content percentages were obtained and programmed. The system was then installed to monitor the moisture content of rubber wood in the dehydration process. The measured results deviated from those obtained from a standard method in the range of 7.67–15.38%. The error compensation was analyzed to improve the measured results that provided the deviated moisture content in the range of 3.58–5.21%. It can be inferred that the proposed sensor system has the capability to be implemented in industrial dehydration processes. Full article

This paper presents a novel ultrathin frequency selective surface (FSS) bandpass filter with an extraordinary wideband tailored for operating within the S-C bands. The filter structure entails a double-layer FSS structure with mutually perpendicular unit cells etched on the top and bottom sides of a 0.003${\lambda }_L$ thick FR4 dielectric substrate, where ${\lambda }_L$ is the free space wavelength at the lowest operating frequency. Thus, both TE and TM polarizations can be covered, ensuring the polarization insensitivity of the structure. The two FSS layers are loaded with resistors to implement the harmonic suppression principle. The overall periodicity is extremely compact, measuring 0.16${\lambda }_L$× 0.16${\lambda }_L$. An equivalent circuit analysis was conducted to comprehensively evaluate the structure and provide design guidelines. Numerical simulations and experimental measurements demonstrated that the proposed filter achieved a −3 dB transmission band spanning from 2 to 6.76 GHz (fractional bandwidth equal to 108.7%) under normal incidence. Moreover, aside from excellent wideband performance, the filter showcased a flat bandpass and stable responses up to 40° of incidence angle. These remarkable capabilities position the proposed filter as a valuable asset in advancing the development of radomes and applications relevant to electromagnetic interference (EMI) shielding, promising significant contributions to the field. Full article