Search Results (9)

Urban open spaces (UO) play a crucial role in urban environments, particularly in areas where social and economic activities are rapidly increasing. However, the challenges of high inter-class similarity, complex environmental surroundings, and scale variations often result in suboptimal performance in UO mapping. To address these issues, this paper proposes UOSAM, a novel approach that leverages the Segment Anything Model (SAM) for efficient UO mapping using high-resolution remote sensing images. Our method employs a pyramid transformer to extract feature pyramids at multiple scales, capturing multi-scale semantic context and addressing the issue of scale variation. Additionally, SAM is used to achieve the more precise geometry segmentation of ubiquitous objects within the images, effectively tackling the challenges posed by their high inter-class similarity and environmental complexity. Furthermore, we introduce a feature fusion module (FFM) that integrates multi-level features from the remote sensing images. Extensive experiments conducted on the Urban Openspace China Ten Cities (UOCTC) dataset from ten major cities in China, using manually annotated samples, demonstrate the superiority of the proposed UOSAM. Full article

Gross primary productivity (GPP) quantifies the rate at which plants convert atmospheric carbon dioxide into organic matter through photosynthesis, playing a vital role in the terrestrial carbon cycle. Machine learning (ML) techniques excel in handling spatiotemporally complex data, facilitating accurate spatial-scale inversion of forest GPP by integrating limited ground flux measurements with Remote Sensing (RS) observations. Enhancing ML algorithm performance for precise GPP estimation is a key research focus. This study introduces the Random Grid Search Algorithm (RGSA) for hyperparameters tuning to improve Random Forest (RF) and eXtreme Gradient Boosting (XGB) models across four major forest regions in China. Model optimization progressed through three stages: the Unoptimized (UO) XGB model achieved $R^2$ = 0.77 and $RMSE$ = 1.42 g Cm⁻² d⁻¹; the Hyperparameter Optimized (HO) XGB model using RGSA improved performance by 5.19% in $R^2$ (0.81) and reduced $RMSE$ by 9.15% (1.29 g Cm⁻² d⁻¹); the Hyperparameter and Variable Combination Optimized (HVCO) XGB model with selected variables (LAI, Temp, NR, VPD, and NDVI) further enhanced $R^2$ to 0.83 and decreased $RMSE$ to 1.23 g Cm⁻² d⁻¹. The optimized GPP estimates exhibited high spatial consistency with existing high-quality products like GOSIF GPP, GLASS GPP, and FLUXCOM GPP, validating the model’s reliability and effectiveness. This research provides crucial insights for improving GPP estimation accuracy and optimizing ML methodologies for forest ecosystems in China. Full article

A new Ni coordination polymer [Ni(MIP)(BMIOPE)]_n (1) was constructed (BMIOPE = 4,4′-bis(2-methylimidazol-1-yl)diphenyl ether, and H₂MIP = 5-methylisophthalic acid), possessing two-dimensional (2D) twofold parallel interwoven net structure with a 4⁴∙6² point symbol. Complex 1 has been successfully obtained based on mixed-ligand strategy. The fluorescence titration experiments revealed that complex 1 could act as multifunctional luminescent sensor to simultaneously detect UO₂²⁺, Cr₂O₇²⁻ and CrO₄²⁻, and NFT (nitrofurantoin). The limit of detection (LOD) values for complex 1 are 2.86 × 10⁻⁵, 4.09 × 10⁻⁵, 3.79 × 10⁻⁵ and 9.32 × 10⁻⁵ M for UO₂²⁺, Cr₂O₇²⁻, CrO₄²⁻ and NFT. The K_sv values are 6.18 × 10³, 1.44 × 10⁴, 1.27 × 10⁴ and 1.51 × 10⁴ M⁻¹ for NFT, CrO₄²⁻, Cr₂O₇²⁻ and UO₂²⁺. Finally, the mechanism of its luminescence sensing is studied in detail. These results manifest that complex 1 is a multifunctional sensor for sensitive fluorescent UO₂²⁺, Cr₂O₇²⁻, CrO₄²⁻ and NFT detection. Full article

Applications requiring services from modern wireless networks, such as those involving remote control and supervision, call for maintaining the timeliness of information flows. Current research and development efforts for 5G, Internet of things, and artificial intelligence technologies will benefit from new notions of timeliness in designing novel sensing, computing, and transmission strategies. The age of information (AoI) metric and a recent related urgency of information (UoI) metric enable promising frameworks in this direction. In this paper, we consider UoI optimization in an interactive point-to-point system when the updating terminal is resource constrained to send updates and receive/sense the feedback of the status information at the receiver. We first propose a new system model that involves Gaussian distributed time increments at the receiving end to design interactive transmission and feedback sensing functions and develop a new notion of UoI suitable for this system. We then formulate the UoI optimization with a new objective function involving a weighted combination of urgency levels at the transmitting and receiving ends. By using a Lyapunov optimization framework, we obtain a decision strategy under energy resource constraints at both transmission and receiving/sensing and show that it can get arbitrarily close to the optimal solution. We numerically study performance comparisons and observe significant improvements with respect to benchmarks. Full article

Urban open spaces (UOS) provide an everyday environment for residents to experience nature. However, the management of UOS—from zoning to construction and maintenance—tends to follow efficient and straight-forward processes lacking use of residents’ experiences. This study first collected the views of management professionals on how participation can best benefit management of UOS. Second, a survey used biodiversity as a case to clarify how the ongoing changes in urban biotopes challenge conventional management of UOS. The results showed that especially in the maintenance phase of current UOS management there is potential to further involve residents in a continuous dialogue and activities to account for local perceptions, including residents’ sensing and emotions raised by UOS. Such involvement may facilitate positive human-nature relations but may require new modes of interaction. We thus propose such adaptive management to foster residents’ contribution to sustainability transition. Full article

Covalent organic framework (COF) has been attracting considerable attention as a novel crystalline material owing to its extended π-electron conjugation and excellent spectral behavior. In this study, we present an imine-linked two-dimensional (2D) crystalline sulfone-based covalent organic framework (TAS-COF) synthesized by 2,4,6-triformylphloroglucinol (Tp) and 3,7-diaminodibenzo[b,d]thiophene (DAS) via a Schiff base condensation reaction. The benzothiophene sulfone endows the as-synthesized TAS-COF with excellent oxidase-like activity under visible light irradiation, ascribed to the generation of superoxide radicals (O₂^•−) by photo-generated electron transfer. TAS-COF can efficiently oxidase the colorless substrate 3,3′,5,5′-tetramethylbenzydine (TMB) into blue oxidized TMB (oxTMB) when exposed to visible light, and the presence of uranium (UO₂²⁺) leads to clear color fading due to the coordination between the imine of oxTMB and UO₂²⁺. A colorimetric strategy is thus developed for UO₂²⁺ determination with a detection limit of 0.07 μmol L⁻¹. Moreover, a paper-based visual sensing platform is also constructed to offer simple and fast UO₂²⁺ content evaluation in water samples. The present study not only provides a promising strategy to prepare visible light-triggered COF-based metal-free nanoenzymes but also extends the applications of COF material in radionuclide detection. Full article

The 1,2,3-Triazole derivatives containing the sulfonyl group have proved their biological importance in medicinal chemistry and drug design. In this sense, we describe the regioselective synthesis of 2-(phenylsulfonyl)-2H-1,2,3-triazole 3 in good yield through a classical sulfonamidation reaction of 1H-1,2,3-triazole 1 with benzenesulfonyl chloride 2 in dichloromethane using a slight excess of triethylamine at 20 °C for 3 h. This procedure is distinguished by its short reaction time, high yield, excellent regioselectivity, clean reaction profile, and operational simplicity. The sulfonamide 3 was characterized by high-resolution mass spectrometry, FT–IR, UV–Vis, 1D and 2D NMR spectroscopy, and elemental analysis. The sulfonamide 3 exhibited moderate activity against UO-31 renal, SNB-75 central nervous system, HCT-116 colon, and BT-549 breast cancer cell lines, with growth inhibition percentages (GI%) ranging from 10.83% to 17.64%. Full article

A simple to realize optical fiber sensor specific for uranium(VI) detection in water is reported to demonstrate the sensing approach’s capability to determine uranyl (UO₂²⁺) in water solution in the ppb range. The proposed sensor was obtained by combining a specific receptor layer for uranium to a gold thin film at which the surface plasmon resonance (SPR) phenomenon takes place via optical fiber. In particular, an SPR D-shaped plastic optical fiber (POF) probe was used for signal transduction. The proposed optical-chemical sensing method is attractive because, in principle, it can be applied directly in the field, giving an analytical response in a fast and not overly expensive manner. Full article

The continuous growth of interconnected devices in the Internet of Things (IoT) presents a challenge in terms of network resources. Cognitive radio (CR) is a promising technology that can address the IoT spectral demands by enabling an opportunistic spectrum access (OSA) scheme. The application of full duplex (FD) radios in spectrum sensing enables secondary users (SUs) to perform sensing and transmission simultaneously, and improves the utilization of the spectrum. However, random and dense distributions of FD-enabled SU transmitters (FD-SU TXs) with sensing capabilities in small-cell CR-IoT environments poses new challenges, and creates heterogeneous environments with different spectral opportunities. In this paper, we propose a spatial and temporal spectral-hole sensing framework for FD-SU TXs deployed in CR-IoT spectrum-heterogeneous environment. Incorporating the proposed sensing model, we present the analytical formulation and an evaluation of a utilization of spectrum (UoS) scheme for FD-SU TXs present at different spatial positions. The numerical results are evaluated under different network and sensing parameters to examine the sensitivities of different parameters. It is demonstrated that self-interference, primary user activity level, and the sensing outcomes in spatial and temporal domains have a significant influence on the utilization performance of spectrum. Full article