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- 2019
- low-temperature electronics
- differential operational amplifier
- LTspice environment
- differential stage
- common-mode rejection ratio
- junction field-effect transistors
- Electronic Science and Technology
- Don State Technical University
- Southern Federal University
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On-line measurement of fluorescent aerosols near an industrial zone in the Yangtze River Delta region using a wideband integrated bioaerosol spectrometer
摘要： In this work, we present on-line fluorescent aerosol measurements by the wideband integrated bioaerosol spectrometer (WIBS-4A) near an industrial zone in Nanjing, a megacity in the Yangtze-River-Delta (YRD) region. The fieldwork was conducted from April 1 to May 8, 2014. A TSI. 3321 aerosol-particle-sizer (APS) was simultaneously deployed to measure the total number size distribution of aerosol with diameter from 0.8–20 μm. Both WIBS-4A and APS reported similar number concentration and temporal profiles (R2 = 0.72). However, the daily average number of potential bioaerosols was only 0.5 ± 0.2% of the total particles detected by the WIBS-4A and displayed a completely different diurnal profile from that of APS. In addition, WIBS-4A can only provide integrated fluorescent signals, which strongly limited the potential to specifically identify the bioaerosols. Accordingly, hierarchical-agglomerative-cluster-analysis (HACA) was utilized to identify and speciate the potential bioaerosols from the WIBS-4A dataset. By maximizing the total distances among all potential cluster centers, a 12-cluster solution was accepted as the optimum result. These clusters were further identified according to their fluorescent signatures, size, and morphology, i.e., non-bioaerosols, bacteria, and fungal spores and/or pollen fragments. Bacteria were the dominant bioaerosol species detected in this work. The diurnal profiles of bioaerosols correlated very well with relatively humidity (RH), reaching daily maxima around 3 AM~6 AM, indicating the presence of humidity controlled bioaerosol emission mechanism, i.e., bacteria may flourish under moderate ambient temperature, RH, and the absence of UV radiation. The size- and AF-distributions of bioaerosols indicated that bioaerosols normally varied substantially in size and assumed a rather irregular shape. Although the number concentration of bioaerosols was relatively small, most bioaerosols can efficiently serve as ice nuclei by providing rough and irregular surfaces, verified by the observation results. Therefore, WIBS-4A measurements can still be informative for investigations of bioaerosols in the atmosphere, especially when HACA method was incorporated into the data processing.
关键词： Hierarchical agglomerative cluster analysis,WIBS-4A,Ice nuclei,Cloud condensation nuclei,Primary biological aerosol
更新于2025-09-23 15:23:52
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2D reentrant micro-honeycomb structure of graphene-CNT in polyurethane: High stretchability, superior electrical/thermal conductivity, and improved shape memory properties
摘要： The recent rapid development of soft electronics and wearable technology has demanded materials with the function of combining mechanical deformation and electronics. Particularly, materials simultaneously having memory shape characteristics in which mechanical deformation repeatedly occurs in response to stimulus, high stretchability and excellent electric/heat transfer characteristics are interesting actuator materials in future applications. As a stretchable and conductive platform, we fabricated a reentrant micro-honeycomb structure from graphene-CNT, which had structural stretchability due to the accordion-like reentrant structure and continuous conductive paths in the vertical and horizontal directions. To impart shape memory properties, we fabricated composites by simply infiltrating shape memory polyurethane (SMPU) into a stable graphene/CNT framework. Our resulting reentrant micro-honeycomb graphene-CNT/SMPU composites simultaneously exhibited a relatively low resistivity of 5 Ω cm, a change in resistance of less than 10% in the 50% stretching/releasing states, long term stability, and superior tensile shape memory properties, including 95.6% shape fixity and a 90.6% recovery ratio. Regularly distributed graphene-CNT structures offer heterogeneous nucleation sites and undisturbed crystal growth in neat SMPU pillars, resulting in superior shape memory properties. We also constructed a circuit with portable batteries to demonstrate that our reentrant graphene-CNT/SMPU composite offers potential applications as an emergency circuit breaker.
关键词： Shape memory,Polyurethane,Reentrant graphene-CNT,Composite,Ice-templated self-assembly
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Sea Ice Change Detection in SAR Images Based on Collaborative Representation
摘要： Sea ice change detection from synthetic aperture radar (SAR) images is important for navigation safety and natural resource extraction. This paper proposed a sea ice change detection method from SAR images based on collaborative representation. First, neighborhood-based ratio is used to generate a difference image (DI). Then, some reliable samples are selected from the DI by hierarchical fuzzy C-means (FCM) clustering. Finally, based upon these samples, collaborative representation method is utilized to classify pixels from the original SAR images into unchanged and changed class. From there, the final change map can be obtained. Experimental results on two real sea ice datasets demonstrate the superiority of the proposed method over two closely related methods.
关键词： sea ice change detection,synthetic aperture radar,clustering method,collaborative representation
更新于2025-09-23 15:23:52
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[IEEE 2018 17th International Conference on Ground Penetrating Radar (GPR) - Rapperswil, Switzerland (2018.6.18-2018.6.21)] 2018 17th International Conference on Ground Penetrating Radar (GPR) - Full-polarimetric GPR for detecting ice fractures
摘要： The real-time monitoring of ice fracture width and direction is of great significance for the safety of Antarctic scientific expedition and the understanding of the process of ice fracture induced by avalanches. Using full-polarimetric ground penetrating radar (GPR) system to detect ice cracks, the scattering matrix is obtained and processed by polarization decomposition. Compared with the traditional pulse radar, more comprehensive and more intuitive information of ice cracks can be obtained. By using the Pauli decomposition method in polarization decomposition, the forward data obtained by the three-dimensional finite difference time domain (FDTD) method is processed, and the applicability of the proposed decomposition method is proved. For testing the feasibility, we performed numerical and laboratory experiments and applied the Pauli decomposition to the GPR data for ice fracture characterization. On this basis, the method is used to imaging small scale ice cracks on the lake surface, and good results are achieved, which paves the way for further practical application.
关键词： full-polarimetric GPR,decomposition,ice fracture detection
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - L-Band Radar Sounder for Measuing Ice Basal Conditions and Ice-Shelf Melt Rate
摘要： A new L-band radar system is proposed to measure ice thickness, basal conditions and ice-shelves bottom melt rates. The concept for ice measurements with an L-band radar is based on the recent success in sounding shallow low-loss ice (< 1 km) and measuring ice-self melt rates with a 600-900 MHz low-power radar, referred to as accumulation radar [1]. A surface-based radar operating over 1.2-1.4 GHz with a peak transmit power of 2 kW is proposed to sound and image more than 4 km thick ice. The higher frequency at 1.3 GHz will provide the sensitivity required to detect basal water film as thin as 0.5 mm as compared to radars operating now at frequencies less than 600 MHz. These radars need a minimum film thickness of 4 mm or more for reliable detection. The proposed L-band radar will also measure the bottom melt rate of ice shelves. The current plan is to deploy the proposed radar for field test in Antarctica during the 2018-2019 field season.
关键词： L-band,sounder,ice,Radar
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - First in-Situ Demonstration of Passive Radio Sounding Using the Sun as a Source for Echo Detection
摘要： While radio echo sounders are powerful tools used to constrain subglacial conditions, current ice-penetrating radar systems are too resource intensive for multiyear deployment at a large scale. To address this, we present passive radio sounding as a low resource approach for observing the subsurface of ice sheets and glaciers. Although passive radar has been used for target tracking and military purposes, it has never been implemented for ice sounding. Nevertheless, recent work has proposed the passive radio sounding of Europa’s icy shell using Jupiter’s decametric radiation as a source for echo detection [1,2]. Expanding on this idea, we evaluate and discuss the challenges of developing a passive radio sounder that uses the Sun for echo detection. Our prototype measures the Sun’s direct and reflected path off the ocean to obtain the height of a cliff along the California coast. This serves as the first in-situ demonstration of an autocorrelation-based passive-sounder using a compact astronomical white noise source.
关键词： ice-penetrating radar,passive radar,radio echo sounding
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Validation of SAR Iceberg Detection with Ground-Based Radar and GPS Measurements
摘要： Calving of icebergs at the tidewater glacier fronts is a component of the mass loss in Polar regions. Studying the regional distribution of icebergs, their volume, motion, and interaction with the environment is of interest. Here, we present the results from a fieldwork campaign conducted in Kongsfjorden, Svalbard in April 2016, where both satellite and ground-based remote sensing instruments were used to observe dynamics of sea ice, icebergs, and growlers. We used a ground-based radar system, imaging the study area every second minute during five days. During the same observation period, we collected four RADARSAT-2 (RS-2) quad-pol images, that are used for automatic detection of icebergs. In addition, the fieldwork team collected GPS positions of some drifting and grounded icebergs in the fjord to be used as ground-truth data. The comparison and combination of satellite, ground-based radar, and in-situ data contribute to cross-validate the results.
关键词： synthetic aperture radar,ground-based radar,polarimetry,GPS mapping,Iceberg,detection,sea ice
更新于2025-09-23 15:22:29
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Semi-Automated Classification of Lake Ice Cover Using Dual Polarization RADARSAT-2 Imagery
摘要： Lake ice is a significant component of the cryosphere due to its large spatial coverage in high-latitude regions during the winter months. The Laurentian Great Lakes are the world’s largest supply of freshwater and their ice cover has a major impact on regional weather and climate, ship navigation, and public safety. Ice experts at the Canadian Ice Service (CIS) have been manually producing operational Great Lakes image analysis charts based on visual interpretation of the synthetic aperture radar (SAR) images. In that regard, we have investigated the performance of the semi-automated segmentation algorithm “glocal” Iterative Region Growing with Semantics (IRGS) for lake ice classification using dual polarized RADARSAT-2 imagery acquired over Lake Erie. Analysis of various case studies indicated that the “glocal” IRGS algorithm could provide a reliable ice-water classification using dual polarized images with a high overall accuracy of 90.4%. However, lake ice types that are based on stage of development were not effectively identified due to the ambiguous relation between backscatter and ice types. The slight improvement of using dual-pol as opposed to single-pol images for ice-water discrimination was also demonstrated.
关键词： RADARSAT-2,classification,lake ice,synthetic aperture radar
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Retrieval and Validation of Sea Ice Concentration from AMSR-E/AMSR2 in Polar Regions
摘要： Sea ice concentration (SIC) is an important sea ice parameter of the atmosphere-ice-ocean system in the polar region. Daily 6.25 km AMSR-E/AMSR2 SIC from Bremen University (UB) is one of the widely used SIC products. In this paper, MODIS data and aerial image are used to validate this product. The results show that the daily mean AMSR-E ASI products underestimate SICs about 17.9% based on the aerial image, and underestimate SICs about8.5% based on MODIS image. The sea ice extent (SIE) and sea ice area (SIA) which are derived from SIC by ASI algorithm, Dynamic Tie-point ASI algorithm (DT-ASI) as well as NT algorithm are compared.
关键词： Retrieval,Validation,aerial image,Sea ice concentration,AMSR-E,MODIS
更新于2025-09-23 15:22:29
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New Optical Properties of Ice Crystals for Multi-Class Cloud Microphysics
摘要： New optical properties of ice crystals were implemented in a general circulation model (GCM). Ebert and Curry’s (1992) and Fu’s (1996) parametrizations are widely used in the GCM radiation scheme. However, the validity of the data is limited to an effective radius (size) of 130 or 140 μm. This limit exceeds the median of the effective radius of snow (~200 μm), which is computed from the multi-class cloud microphysics scheme. A comparable amount of snow exists in the upper atmosphere near the lower part of ice clouds. Although the cross section of snow (extinction probability) is smaller than cloud ice, its impact on radiation has not been properly considered so far. We constructed a new lookup table of optical properties based on recent data for an extended effective radius up to 500 μm. The old data (< 130 μm) also need to be updated with a more recent and elaborate method. We processed extensive data provided by Yang et al. (2013) and linked to the radiation module of the Korean Integrated Model (KIM). The new optical properties change the shortwave scattering features, thus increasing the heating rate. This tendency is checked in both one-dimensional and global weather forecast simulations. With the new optical properties, KIM shows better performance by reducing bias with respect to the Integrated Forecasting Systems (IFS) analysis data.
关键词： weather forecasting,optical properties,cloud microphysics,ice crystals,radiation scheme
更新于2025-09-23 15:21:21