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Cloud radiative effect, cloud fraction and cloud type at two stations in Switzerland using hemispherical sky cameras
摘要： The current study analyses the cloud radiative effect during the daytime depending on cloud fraction and cloud type at two stations in Switzerland over a time period of 3 to 5 years. Information on fractional cloud coverage and cloud type is retrieved from images taken by visible all-sky cameras. Cloud-base height (CBH) data are retrieved from a ceilometer and integrated water vapour (IWV) data from GPS measurements. The longwave cloud radiative effect (LCE) for low-level clouds and a cloud coverage of 8 oktas has a median value between 59 and 72 Wm?2. For mid- and high-level clouds the LCE is significantly lower. It is shown that the fractional cloud coverage, the CBH and IWV all have an influence on the magnitude of the LCE. These observed dependences have also been modelled with the radiative transfer model MODTRAN5. The relative values of the shortwave cloud radiative effect (SCErel) for low-level clouds and a cloud coverage of 8 oktas are between ?90 and ?62 %. Also here the higher the cloud is, the less negative the SCErel values are. In cases in which the measured direct radiation value is below the threshold of 120 Wm?2 (occulted sun) the SCErel decreases substantially, while cases in which the measured direct radiation value is larger than 120 Wm?2 (visible sun) lead to a SCErel of around 0 %. In 14 and 10 % of the cases in Davos and Payerne respectively a cloud enhancement has been observed with a maximum in the cloud class cirrocumulus–altocumulus at both stations. The calculated median total cloud radiative effect (TCE) values are negative for almost all cloud classes and cloud coverages.
关键词： cloud radiative effect,Switzerland,cloud type,cloud fraction,hemispherical sky cameras
更新于2025-09-09 09:28:46
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Quantum information exchange protocol associated with the quantum cloud
摘要： Quantum cryptography discusses the security of quantum information. Cloud computing has emerged as a computational paradigm and an alternative to the conventional computing. Cloud security is associated with cloud computing. In this paper, we define the new concept about quantum cloud and discuss the security of quantum information exchange in quantum internet. A tripartite simultaneous quantum information exchange protocol associated with the quantum cloud based on entanglement swapping and Bell states is proposed. The proposed secure quantum information exchange protocol can resist intercept-and-resend attack, intercept-and-measure attack, intercept-and-entangle auxiliary attack and denial-of-service attack. It can also be generalised to N-party case that is feasible and efficient.
关键词： intercept-and-resend attack,cloud computing,quantum information exchange,intercept-and-measure attack,intercept-and-entangle auxiliary attack,denial-of-service attack,quantum cloud
更新于2025-09-09 09:28:46
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A Physics-based Smart Persistence model for Intra-hour forecasting of solar radiation (PSPI) using GHI measurements and a cloud retrieval technique
摘要： Short-term solar forecasting models based solely on global horizontal irradiance (GHI) measurements are often unable to discriminate the forecasting of the factors affecting GHI from those that can be precisely computed by atmospheric models. This study introduces a Physics-based Smart Persistence model for Intra-hour forecasting of solar radiation (PSPI) that decomposes the forecasting of GHI into the computation of extraterrestrial solar radiation and solar zenith angle and the forecasting of cloud albedo and cloud fraction. The extraterrestrial solar radiation and solar zenith angle are accurately computed by the Solar Position Algorithm (SPA) developed at the National Renewable Energy Laboratory (NREL). A cloud retrieval technique is used to estimate cloud albedo and cloud fraction from surface-based observations of GHI. With the assumption of persistent cloud structures, the cloud albedo and cloud fraction are predicted for future time steps using a two-stream approximation and a 5-min exponential weighted moving average, respectively. Our model evaluation using the long-term observations of GHI at NREL’s Solar Radiation Research Laboratory (SRRL) shows that the PSPI has a better performance than the persistence and smart persistence models in all forecast time horizons between 5 and 60 min, which is more significant in cloudy-sky conditions. Compared to the persistence and smart persistence models, the PSPI does not require additional observations of various atmospheric parameters but is customizable in that additional observations, if available, can be ingested to further improve the GHI forecast. An advanced technology of cloud forecast is also expected to improve the future performance of the PSPI.
关键词： Cloud fraction,Global horizontal irradiance,Smart persistence,Solar forecasting,Cloud albedo
更新于2025-09-09 09:28:46
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Cloud shadow speed sensor
摘要： Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system is presented that measures cloud shadow motion vectors to estimate power plant ramp rates and provide short-term solar irradiance forecasts. The cloud shadow speed sensor (CSS) is constructed using an array of luminance sensors and a high-speed data acquisition system to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud shadow motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground-measured irradiance (linear cloud edge, LCE), and a UC San Diego sky imager (USI). The CSS detected artificial shadow directions and speeds to within 15? and 6 % accuracy, respectively. The CSS detected (real) cloud shadow directions and speeds with average weighted root-mean-square difference of 22? and 1.9 m s?1 when compared to USI and 33? and 1.5 m s?1 when compared to LCE results.
关键词： cloud motion vectors,solar irradiance,cloud shadow speed sensor,forecasting,solar energy
更新于2025-09-09 09:28:46
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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 - Joint Encoding LBP Features from Infrared and Visible-Light Cloud Image Observations for Ground-Based Cloud Classification
摘要： Cloud type classification based on ground-based cloud image observations is an important task in atmospheric research. Currently, two kinds of cloud image observations with infrared and visible light images are widely used for cloud classification. However, they are only independently analyzed and simply compared in the current study. The useful information from these two kinds of images is not fully utilized and integrated. The classification performance could be improved if taking full advantage of the complementary information of these two observations. Thus, first, a database containing these two kinds of cloud images with same temporal resolution is released in this study. Then, a two-observation joint encoding strategy of LBP (local binary pattern) features is proposed to implement cloud classification by encoding the joint distribution of LBP patterns in different observations, which captures the correlation between two observations. Experimental results based on this database show the significant superiority of the proposed method compared to the results based on the single observation.
关键词： infrared cloud images,cloud classification,Local binary patterns,visible light,joint distribution
更新于2025-09-09 09:28:46
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[Advances in Intelligent Systems and Computing] Image Processing and Communications Challenges 10 Volume 892 (10th International Conference, IP&C’2018 Bydgoszcz, Poland, November 2018, Proceedings) || Interference-Aware Virtual Machine Placement: A Survey
摘要： In order to maintain energy e?ciency and optimize resource utilization in cloud datacenters, cloud providers adopt virtualization technologies as well as server consolidation. Virtualization is the means used to achieve multi-tenant environments by creating many virtual machines (VMs) on the same physical machine (PM) in a way that they share same physical resources (e.g. CPU, disk, memory, network I/O, etc.). Server consolidation consists of placing as much as possible VMs on as less as possible PMs, in the aim of maximizing idle servers and then minimize the energy consumption. However, this vision of server consolidation is not as simple as it seems to be. Hence, it is crucial to be aware of its emerging concerns, such as severe performance degradation problem when placing particular VMs on the same PM. Furthermore, the Virtual Machine Placement (VMP) is one of the most challenging problems in cloud environments management and it’s been studied from various perspectives. In this paper, we are going to propose a VMP taxonomy in order to understand the various aspects that researchers consider while de?ning their VMP approaches. We will also survey the most relevant interference-aware virtual machine placement literature and then we shall give a comparative study between them.
关键词： Server Consolidation,Energy Efficiency,Interference-aware,Cloud Computing,Virtual Machine Placement
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Communication and Signal Processing (ICCSP) - Chennai, India (2018.4.3-2018.4.5)] 2018 International Conference on Communication and Signal Processing (ICCSP) - Estimation of Peaks and Canopy Height Using LiDAR Data
摘要： 3D city modelling plays a major role in today’s smart city development. LiDAR facilitates acquisition and processing of point cloud data. The proposed plan in this paper will estimate the height of a building. LiDAR data processing is done by the software, LAS tools. In this paper the study focuses on LiDAR scan of urban scenes (buildings). Canopy Height Model (CHM) of a building is obtained which is useful in finding the height of a building, shape of the building and peak location. This can be a contribution to smart city modeling and urban development. Canopy height model for LiDAR data is obtained through classifiers and filters available in LAStools. Also this paper presents about Digital Terrain Model (DTM) and Digital Surface Model (DSM) for LiDAR point cloud data. Further the obtained CHM can be used for the application of finding the number of buildings in an area which are above a threshold height.
关键词： LAStools,DSM,Point cloud data,DTM,LiDAR scan,Canopy height model
更新于2025-09-09 09:28:46
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Pansharpening for Cloud-Contaminated Very High-Resolution Remote Sensing Images
摘要： The optical remote sensing images not only have to make a fundamental tradeoff between the spatial and spectral resolutions, but also are inevitable to be polluted by the clouds; however, the existing pansharpening methods mainly focus on the resolution enhancement of the optical remote sensing images without cloud contamination. How to fuse the cloud-contaminated images to achieve the joint resolution enhancement and cloud removal is a promising and challenging work. In this paper, a pansharpening method for the challenging cloud-contaminated very high-resolution remote sensing images is proposed. Furthermore, the cloud-contaminated conditions for the practical observations with all the thick clouds, the thin clouds, the haze, and the cloud shadows are comprehensively considered. In the proposed methods, a two-step fusion framework based on multisource and multitemporal observations is presented: 1) the thin clouds, the haze, and the light cloud shadows are proposed to be first jointly removed and 2) a variational-based integrated fusion model is then proposed to achieve the joint resolution enhancement and missing information reconstruction for the thick clouds and dark cloud shadows. Through the proposed fusion method, a promising cloud-free fused image with both high spatial and high spectral resolutions can be obtained. To comprehensively test and verify the proposed method, the experiments were implemented based on both the cloud-free and cloud-contaminated images, and a number of different remote sensing satellites including the IKONOS, the QuickBird, the Jilin (JL)-1, and the Deimos-2 images were utilized. The experimental results confirm the effectiveness of the proposed method.
关键词： remote sensing,image fusion,Pansharpening,cloud contamination,integrated model
更新于2025-09-09 09:28:46
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From LiDAR Waveforms to Hyper Point Clouds: A Novel Data Product to Characterize Vegetation Structure
摘要： Full waveform (FW) LiDAR holds great potential for retrieving vegetation structure parameters at a high level of detail, but this prospect is constrained by practical factors such as the lack of available handy processing tools and the technical intricacy of waveform processing. This study introduces a new product named the Hyper Point Cloud (HPC), derived from FW LiDAR data, and explores its potential applications, such as tree crown delineation using the HPC-based intensity and percentile height (PH) surfaces, which shows promise as a solution to the constraints of using FW LiDAR data. The results of the HPC present a new direction for handling FW LiDAR data and offer prospects for studying the mid-story and understory of vegetation with high point density (~182 points/m2). The intensity-derived digital surface model (DSM) generated from the HPC shows that the ground region has higher maximum intensity (MAXI) and mean intensity (MI) than the vegetation region, while having lower total intensity (TI) and number of intensities (NI) at a given grid cell. Our analysis of intensity distribution contours at the individual tree level exhibit similar patterns, indicating that the MAXI and MI decrease from the tree crown center to the tree boundary, while a rising trend is observed for TI and NI. These intensity variable contours provide a theoretical justification for using HPC-based intensity surfaces to segment tree crowns and exploit their potential for extracting tree attributes. The HPC-based intensity surfaces and the HPC-based PH Canopy Height Models (CHM) demonstrate promising tree segmentation results comparable to the LiDAR-derived CHM for estimating tree attributes such as tree locations, crown widths and tree heights. We envision that products such as the HPC and the HPC-based intensity and height surfaces introduced in this study can open new perspectives for the use of FW LiDAR data and alleviate the technical barrier of exploring FW LiDAR data for detailed vegetation structure characterization.
关键词： vegetation structure,HPC-based intensity surface,percentile height,tree segmentation,gridding,hyper point cloud (HPC),full waveform LiDAR
更新于2025-09-09 09:28:46
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3D Building Roof Modeling by Optimizing Primitive’s Parameters Using Constraints from LiDAR Data and Aerial Imagery
摘要： In this paper, a primitive-based 3D building roof modeling method, by integrating LiDAR data and aerial imagery, is proposed. The novelty of the proposed modeling method is to represent building roofs by geometric primitives and to construct a cost function by using constraints from both LiDAR data and aerial imagery simultaneously, so that the accuracy potential of the different sensors can be tightly integrated for the building model generation by an integrated primitive’s parameter optimization procedure. To verify the proposed modeling method, both simulated data and real data with simple buildings provided by ISPRS (International Society for Photogrammetry and Remote Sensing), were used in this study. The experimental results were evaluated by the ISPRS, which demonstrate the proposed modeling method can integrate LiDAR data and aerial imagery to generate 3D building models with high accuracy in both the horizontal and vertical directions. The experimental results also show that by adding a component, such as a dormer, to the primitive, a variant of the simple primitive is constructed, and the proposed method can generate a building model with some details.
关键词： building modeling,optimization,primitive,LiDAR,aerial imagery,model-based,data fusion,point cloud
更新于2025-09-09 09:28:46