- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Terrestrial Remote Sensing of Snowmelt in a Diverse High-Arctic Tundra Environment Using Time-Lapse Imagery
摘要： Snow cover is one of the crucial factors influencing the plant distribution in harsh Arctic regions. In tundra environments, wind redistribution of snow leads to a very heterogeneous spatial distribution which influences growth conditions for plants. Therefore, relationships between snow cover and vegetation should be analyzed spatially. In this study, we correlate spatial data sets on tundra vegetation types with snow cover information obtained from orthorectification and classification of images collected from a time-lapse camera installed on a mountain summit. The spatial analysis was performed over an area of 0.72 km2, representing a coastal tundra environment in southern Svalbard. The three-year monitoring is supplemented by manual measurements of snow depth, which show a statistically significant relationship between snow abundance and the occurrence of some of the analyzed land cover types. The longest snow cover duration was found on 'rock debris' type and the shortest on 'lichen-herb-heath tundra', resulting in melt-out time-lag of almost two weeks between this two land cover types. The snow distribution proved to be consistent over the different years with a similar melt-out pattern occurring in every analyzed season, despite changing melt-out dates related to different weather conditions. The data set of 203 high resolution processed images used in this work is available for download in the supplementary materials.
关键词： tundra vegetation,arctic,snow cover dynamics,snowmelt,orthorectification,time-lapse photography,ground based camera,Svalbard,tundra environment
更新于2025-09-23 15:23:52
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Temperature fiber sensing of Li-ion batteries under different environmental and operating conditions
摘要： In this work, a network of fiber sensors has been developed for real time, in situ, and in operando multipoint monitoring the surface temperature distribution on a smartphone Li-ion battery (LiB). Different temperature and relative humidity conditions are considered, in order to mimic the LiB response in the dry, temperate, and cold climates. In total, the temperature variations that occur in five different locations of the LiB are monitored, during constant current charge and different discharge rates, under normal and abusive operating conditions, performing a thermal spatial mapping of the battery surface. In general, the sensors detect temperature variations according to the voltage signal change and faster variations of voltage usually translate in higher temperature rise at the LiB surface. For instance, under abusive discharge, where the voltage drop is fast, the temperature increases at least twice when compared to the normal operating conditions. Absolute temperature values as high as (65.0 ± 0.1) °C are detected by the optical sensor located near the electrodes, under the higher discharge rate (5.77 C) and dry climate. A thermal gradient is identified from the top to the bottom on the LiB surface during the experimental tests. A lower battery performance is observed when it operates under the cold climate, with maximum temperature variations of (30.0 ± 0.1) °C for the higher discharge rate. These results can be helpful to design of next generation of LiBs, improving a faster cooling in critical areas, in order to reduce accumulated heat and preventing consequences such as thermal runaway and failure.
关键词： Fiber Bragg grating sensors,Temperature monitoring,Abnormal operating conditions,Environment,Safety,Li-ion batteries
更新于2025-09-23 15:23:52
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Hybrid Camera Array-Based UAV Auto-Landing on Moving UGV in GPS-Denied Environment
摘要： With the rapid development of Unmanned Aerial Vehicle (UAV) systems, the autonomous landing of a UAV on a moving Unmanned Ground Vehicle (UGV) has received extensive attention as a key technology. At present, this technology is confronted with such problems as operating in GPS-denied environments, a low accuracy of target location, the poor precision of the relative motion estimation, delayed control responses, slow processing speeds, and poor stability. To address these issues, we present a hybrid camera array-based autonomous landing UAV that can land on a moving UGV in a GPS-denied environment. We first built a UAV autonomous landing system with a hybrid camera array comprising a fisheye lens camera and a stereo camera. Then, we integrated a wide Field of View (FOV) and depth imaging for locating the UGV accurately. In addition, we employed a state estimation algorithm based on motion compensation for establishing the motion state of the ground moving UGV, including its actual motion direction and speed. Thereafter, according to the characteristics of the designed system, we derived a nonlinear controller based on the UGV motion state to ensure that the UGV and UAV maintain the same motion state, which allows autonomous landing. Finally, to evaluate the performance of the proposed system, we carried out a large number of simulations in AirSim and conducted real-world experiments. Through the qualitative and quantitative analyses of the experimental results, as well as the analysis of the time performance, we verified that the autonomous landing performance of the system in the GPS-denied environment is effective and robust.
关键词： GPS-denied environment,moving UGV,UAV autonomous landing,hybrid camera array,motion compensation
更新于2025-09-23 15:23:52
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Determination of 17β-estradiol by surface-enhanced Raman spectroscopy merged with hybridization chain reaction amplification on Au@Ag core-shell nanoparticles
摘要： The authors describe an aptamer-based assay for 17β-estradiol. It relies on the combined use of surface enhanced Raman scattering (SERS) and hybridization chain reaction (HCR). The aptamer against 17β-estradiol is applied as the recognition probes, and this results in excellent specificity. Specific recognition of target 17β-estradiol induce the freedom of DNA 2, which will open the stem-loop structure of probe 1 on the Au@Ag and form the partial dsDNA structure. With the nicking enzyme, the partial dsDNA will be hydrolyzed and the reside ssDNA on Au@Ag will form a small stem-loop structure. With the help of the other probe 2 modified Au@Ag and pre-immobilized probe 3 on the well of the microplate, an enzyme-free HCR can occur and tremendous Au@Ag can be assembled along the formed dsDNA in HCR, which can act as the excellent substrate for Raman measurement and greatly amplify the Raman signal of R6G on the Au@Ag. Afterwards, the key factor, ratio between probe 2-Au@Ag (P2) and probe1-Au@Ag (P1), affects the detection sensitivity is systematically optimized for the best sensing performance. The SERS signal of R6G, best measured at 1651 cm?1, increases linearly in the wide range from 1 pM to 10 nM. The detection limit can be as low as 0.1 pM.
关键词： Estrogen,Hybridization chain reaction,SERS,Food safety,Aptamer,Gold nanoparticle,Signal amplification,Environment monitoring
更新于2025-09-23 15:23:52
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Ethanol-Precipitable Silica-Passivated Perovskite Nanocrystals Incorporated into Polystyrene Microspheres for Long-Term Storage and Re-Usage
摘要： Perovskite nanocrystals (PNCs) are emerging luminescent materials due to their fascinating physic-optical properties. However, their sensitive surface chemistry with organic polar solvents, oxygen and moisture greatly hinders their developments towards practical applications. Herein we promote silica-passivated PNCs (SP-PNCs) by in situ hydrolyzing the surface ligands of (3-aminopropyl) triethoxysilane. The resultant SP-PNCs possesses a high quantum yield (QY) of 80% and are precipitable by polar solvents, such as ethanol and acetone, without destroying their surface chemistry or losing QY, which offers an eco-friendly and efficient method for separation, purification and phase transfer of PNCs compared with the traditional solvent evaporation technique. Moreover, we further promoted a swelling-deswelling encapsulation process to incorporate the as-made SP-PNCs into polystyrene microspheres (PMs), which can largely increase the stability of the SP-PNCs against moisture for long-term storage. Besides, the embedded SP-PNCs can also be reused and mono-dispersed by totally dissolving the PMs in suitable solvents for making all-solution-processed devices. We thereby believe this work should open new avenues for greener synthesis, scalable production, and long-term storage of PNCs towards the emerging practical applications.
关键词： stability,perovskite nanocrystals,surface engineering,encapsulation,polar environment
更新于2025-09-23 15:23:52
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Probing Polarity and Heterogeneity of Lipid Droplets in Live Cells Using a Push–Pull Fluorophore
摘要： Lipid droplets (LDs) are organelles composed of a lipid core surrounded by a phospholipid monolayer. Lately, LDs attracted a considerable attention due to recent studies demonstrating their role in a variety of physiological processes as well as diseases. Herein we synthesized a push-pull molecule named DAF (Dimethyl Aniline Furaldehyde) that possesses a strong positive solvatochromism in emission of 119 nm from toluene to methanol. Its impressive fluorogenic properties from water to oil (2000-fold) as well as its high quantum yields (up to 0.97) led us to investigate its ability to sense the distribution of polarity in live cells by fluorescence ratiometric imaging. When added to live cells and excited at 405 nm, DAF immediately and brightly stain lipid droplets using a blue channel (410-500 nm) and cytoplasm in a red channel (500-600 nm). DAF also proved to be compatible with fixation thus allowing 3D imaging of LDs in their cytoplasm environment. Taking advantage of DAF emission in two distinct channels, ratiometric imaging was successfully performed and led to the polarity mapping of the cell unraveling some heterogeneity in polarity within LDs of the same cell.
关键词： Environment Sensitive Fluorescent Probe,Lipid Droplets,Ratiometric Imaging,Multicolor Fluorescent imaging
更新于2025-09-23 15:23:52
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[IEEE 2018 International Flexible Electronics Technology Conference (IFETC) - Ottawa, ON, Canada (2018.8.7-2018.8.9)] 2018 International Flexible Electronics Technology Conference (IFETC) - Electromagnetic Engineered Surface Gratings at 5G Bands Using Printed Electronics
摘要： Electromagnetic engineered surfaces (EES) are a recently introduced concept with the implementation goal of controlling the electromagnetic scattering in communications environments. This paper will focus on EES design techniques to enable the passive extension of line of sight (LoS) coverage into non-LoS regions.
关键词： coverage,electromagnetic engineered surfaces (EES),mm-wave,5G,gratings,communications environment
更新于2025-09-23 15:23:52
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Longtime stability of silver-based SERS substrate in the environment and (bio)environment with variable temperature and humidity
摘要： The increased involving of Surface Enhanced Raman Spectroscopy (SERS) in the analytical and bioanalytical field makes this technique commercially available. However, the growing range of available SERS substrates opens the question regarding the stability of SERS substrates during their storage, transportation, and utilization. In this paper, we present systematical study of the stability of SERS enhanced response of SERS-active silver grating under various physical and chemical loads. The silver coated periodical gratings provide excellent enhancement and reproducibility of SERS signal, achieved at the macroscale. The substrate load procedures include the temperature, humidity tests, and their combination. Since the utilization of SERS substrates often involves their interaction with various (bio)environments, the effects of physiological media were studied too. In all cases, the effects of the loads were determined from the changes of SERS effectivity and reproducibility.
关键词： SERS,Substrate,Temperature,(Bio)environment,Stability,Humidity
更新于2025-09-23 15:23:52
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Work performance in relation to lighting environment in office buildings
摘要： The purpose of this study was to investigate the effect of lighting environment on the work performance. Orthogonal experiments with three-factor and three-level for each factor were designed and carried out in a laboratory aiming to reveal the relationship between lighting illuminance (ILL), uniformity of illuminance (U-ILL), correlated colour temperature (CCT) and workers’ productivity. Twenty-four participants’ work performance was evaluated by subjective questionnaires, objective physiological tests, accompanied with computerized neuro-behavioural tests assessing six kinds of neuro-behavioural functions. Results illustrate that when exposed to high ILL, U-ILL and CCT environment, participants reported highest satisfaction on productivity and attention, while lowest score on stress, difficulty of conducting work and fatigue. The range value and variance analysis from neuro-behavioural tests demonstrated the appropriate level of each factor and the optimal combination. However, they varied with the type of tests illustrating that lighting conditions could influence neuro-behavioural functions differentially. The improvements of perception, learning and memory function of participants were benefited from high ILL, high U-ILL and high/medium CCT. Low ILL, low U-ILL and moderate CCT were appropriate to increase participants’ thinking and executive performance. Moreover, high quality of tear film crystallization was related to higher illuminance. The present study suggests that it is necessary to design personalized illumination environment for particular workplace.
关键词： Subjective evaluation,Office building,Lighting environment,Neurobehavioral tests,Productivity
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Va?ster?s (2018.9.3-2018.9.6)] 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Guidelines for Millimeter-Wave Antenna Measurements
摘要： The characterization of physically small antennas in the millimeter-wave range has proven to be a challenge. Several research groups have developed new antenna measurement systems to be able to characterize millimeter-wave antennas. These measurement systems mainly focus on the establishment of a well-defined connection between test equipment and the antenna-under-test (AUT) for radiation pattern measurements. However, uncertainties affecting the measurement results are not always well understood. We have investigated the effect of misalignment, the effectiveness of an anechoic environment for frequencies up to 90 GHz and the impact of spurious radiation of the probe.
关键词： anechoic environment,probe radiation,60 GHz,probe connection,uncertainty analysis,alignment,Millimeter wave,antenna measurement
更新于2025-09-23 15:23:52