- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2019 IEEE SENSORS - Montreal, QC, Canada (2019.10.27-2019.10.30)] 2019 IEEE SENSORS - Optical fiber methane sensor using refractometry
摘要： Cloud data owners prefer to outsource documents in an encrypted form for the purpose of privacy preserving. Therefore it is essential to develop efficient and reliable ciphertext search techniques. One challenge is that the relationship between documents will be normally concealed in the process of encryption, which will lead to significant search accuracy performance degradation. Also the volume of data in data centers has experienced a dramatic growth. This will make it even more challenging to design ciphertext search schemes that can provide efficient and reliable online information retrieval on large volume of encrypted data. In this paper, a hierarchical clustering method is proposed to support more search semantics and also to meet the demand for fast ciphertext search within a big data environment. The proposed hierarchical approach clusters the documents based on the minimum relevance threshold, and then partitions the resulting clusters into sub-clusters until the constraint on the maximum size of cluster is reached. In the search phase, this approach can reach a linear computational complexity against an exponential size increase of document collection. In order to verify the authenticity of search results, a structure called minimum hash sub-tree is designed in this paper. Experiments have been conducted using the collection set built from the IEEE Xplore. The results show that with a sharp increase of documents in the dataset the search time of the proposed method increases linearly whereas the search time of the traditional method increases exponentially. Furthermore, the proposed method has an advantage over the traditional method in the rank privacy and relevance of retrieved documents.
关键词： security,ciphertext search,hierarchical clustering,multi-keyword search,ranked search,Cloud computing
更新于2025-09-16 10:30:52
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[IEEE 2018 Third International Conference on Electrical, Electronics, Communication, Computer Technologies and Optimization Techniques (ICEECCOT) - Msyuru, India (2018.12.14-2018.12.15)] 2018 International Conference on Electrical, Electronics, Communication, Computer, and Optimization Techniques (ICEECCOT) - Transformer for Distributed Photovoltaic (DPV) Generation
摘要： Mobile fronthaul is an important network segment that bridges wireless baseband units and remote radio units to support cloud radio access network. We review recent progresses on the use of frequency-division multiplexing to achieve highly bandwidth-efficient mobile fronthaul with low latency. We present digital signal processing (DSP) techniques for channel aggregation and deaggregation, frequency-domain windowing, adjacent channel leakage ratio reduction, and synchronous transmission of both the I/Q waveforms of wireless signals and the control words (CWs) used for control and management purposes. In a proof-of-concept experiment, we demonstrate the transmission of 48 20-MHz LTE signals with a common public radio interface (CPRI) equivalent data rate of 59 Gb/s, achieving a low round-trip DSP latency of <2 μs and a low mean error-vector magnitude (EVM) of ～2.5% after fiber transmission. In a follow-up experiment, we further demonstrate the transmission of 32 20-MHz LTE signals together with CPRI-compliant CWs, corresponding to a CPRI-equivalent data rate of 39.32 Gb/s, in single optical wavelength channel that requires an RF bandwidth of only ～1.6 GHz. After transmission over 5-km standard single-mode fiber, the CWs are recovered without error, while the LTE signals are recovered with an EVM of lower than 3%. Applying this technique to future 5G wireless networks with massive multiple-input multiple-output is also discussed. This efficient mobile fronthaul technique may find promising applications in future integrated fiber/wireless access networks to provide ultrabroadband access services.
关键词： fifth-generation (5G),common public radio interface (CPRI),Cloud radio access network (C-RAN),optical fiber transmission,mobile fronthaul,frequency-division multiplexing (FDM)
更新于2025-09-16 10:30:52
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[IEEE 2018 Signal Processing: Algorithms, Architectures, Arrangements, and Applications (SPA) - Poznan (2018.9.19-2018.9.21)] 2018 Signal Processing: Algorithms, Architectures, Arrangements, and Applications (SPA) - Programmatic Simulation of Laser Scanning Products
摘要： The technology of laser scanning is widely used for producing three-dimensional digital representations of geographic features. The measurement results are usually available in the form of 3D point clouds, which are often used as a transitional data model in various remote sensing applications. Unfortunately, while the costs of Light Detection And Ranging scanners have dropped significantly in recent years, they are still considered to be quite expensive for smaller institutions. In consequence, the process of 3D point cloud acquisition remains a difficult one, requiring investment not only in scanning equipment, but also time to operate it and process the obtained results. However, if the goal does not involve the 3D digitalization of a particular object, but instead the point clouds are required e.g. for testing reconstruction algorithms, in many cases such input data can be successfully substituted with the results of a simulated scanning process, which is far easier to accomplish. This paper presents a programmatic simulator which generates artificial scanning results from solid meshes provided by the user and saves them in the form of point cloud datasets.
关键词： 3D,Laser scanning,Point cloud,Simulation,LiDAR
更新于2025-09-12 10:27:22
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[IEEE IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Yokohama, Japan (2019.7.28-2019.8.2)] IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - A Cloud-Enabled Geospatial Big Data Platform for Disaster Information Services
摘要： Geospatial technologies have been widely used to support decision making in natural disaster responses. There have been various efforts from multiple disasters to use geospatial information and models for disaster preparation, response, and resilience. These separated efforts can be shared and re-used across various sectors using a sustained platform. This paper presents how a platform layered on big data and cloud computing technologies can help achieve this goal. The big data platform enables the accumulation of disaster data, models, services, and applications in spatial information infrastructures (SDI), and improves the capabilities of SDI in supporting disaster risk reduction.
关键词： cloud computing,big data,interoperability,disaster,spatial data infrastructure
更新于2025-09-12 10:27:22
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Precision and Bias Comparison Between Laser and Radar Altimetry Data in the Amundsen Sea Embayment and the Lambert-Amery System of Antarctica
摘要： This article focuses on the precision and bias of laser altimetry data [Ice, Cloud, and Land Elevation Satellite (ICESat)] and radar altimetry data (Envisat) L2 products during the contemporary period from 2003 to 2008 in the Amundsen Sea Embayment (ASE) in West Antarctica (an ice loss region) and the Lambert-Amery System (LAS) in East Antarctica (an ice gain region). We used the crossover method to obtain the elevation differences between ICESat tracks, Envisat tracks, and between ICESat and Envisat tracks. The crossover points were generated and the difference of each crossover pair was calculated as raw data. The standard deviations were then computed from the raw data in a grid cell for both ICESat and Envisat. The precision of both satellites varied as a function of the surface slope in the abovementioned two regions, from 6.6 to 16.6 cm for the ICESat data and from 0.11 to 0.35 m for the Envisat data. The crossover points from ICESat-Envisat showed a mean bias of 0.55 ± 4.00 m for the ASE and 0.45 ± 0.99 m for the LAS, in accordance with the penetration depth of the radar altimetry. The relationship between the precision of the satellite measurements with the slope of the ice sheet and the ice velocity in the study area showed that the regions with gentle slopes and low velocity obtained a better precision of altimetry data.
关键词： Antarctica,Envisat,bias,precision,Ice, Cloud, and Land Elevation Satellite (ICESat)
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE International Conference on Mechatronics and Automation (ICMA) - Tianjin, China (2019.8.4-2019.8.7)] 2019 IEEE International Conference on Mechatronics and Automation (ICMA) - Research on 3D Reconstruction Method Based on Laser Rotation Scanning
摘要： A three-dimensional reconstruction algorithm based on line laser rotation scanning is proposed. The rotating platform vision measurement system is designed. The system calibration method consisting of laser, camera and turntable is studied. The axis-eye calibration algorithm is introduced to register the point cloud in the same coordinate. In the system, the camera driven by the turntable is rotated to scan the target object for three-dimensional measurement. The method can obtain the point cloud information of the object by linear laser rotation scanning, and further recover the geometric shape of the three-dimensional visible surface of the object, which not only meets the requirements of the three-dimensional reconstruction target, but also verifies the feasibility and effectiveness of the system.
关键词： rotating platform,camera calibration,feature point extraction,point cloud reconstruction,3d reconstruction
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Using a CCD Camera Based Imaging Lidar to Profile Boundary Layer Aerosols and Determine Cloud Thickness
摘要： Aerosols play a key role in climate change by affecting earth’s radiation budget, and by influencing cloud properties and precipitation patterns in the atmosphere. Additionally, local and regional air quality is affected by natural and anthropogenic aerosols. Lidar systems are capable of measuring altitude dependent aerosol properties over continuous time spans, and thus are widely used optical remote sensing tools for atmospheric monitoring. In this study, we have utilized a CCD camera-based bistatic imaging Lidar (CLidar) to monitor spatial and temporal distributions of boundary layer aerosols in Nassau, Bahamas.
关键词： CCD camera,boundary layer,cloud thickness,aerosols,Lidar,climate change
更新于2025-09-12 10:27:22
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Deriving Individual-Tree Biomass from Effective Crown Data Generated by Terrestrial Laser Scanning
摘要： Biomass reflects the state of forest management and is critical for assessing forest benefits and carbon storage. The effective crown is the region above the lower limit of the forest crown that includes the maximum vertical distribution density of branches and leaves; this component plays an important role in tree growth. Adding the effective crown to biomass equations can enhance the accuracy of the derived biomass. Six sample plots in a larch plantation (ranging in area from 0.06 ha to 0.12 ha and in number of trees from 63 to 96) at the Mengjiagang forest farm in Huanan County, Jiamusi City, Heilongjiang Province, China, were analyzed in this study. Terrestrial laser scanning (TLS) was used to obtain three-dimensional point cloud data on the trees, from which crown parameters at different heights were extracted. These parameters were used to determine the position of the effective crown. Moreover, effective crown parameters were added to biomass equations with tree height as the sole variable to improve the accuracy of the derived individual-tree biomass estimates. The results showed that the minimum crown contact height was very similar to the effective crown height, and an increase in model accuracy was apparent (with R2 a increasing from 0.846 to 0.910 and root-mean-square error (RMSE) decreasing from 0.372 kg to 0.286 kg). The optimal model for deriving biomass included tree height, crown length from minimum contact height, crown height from minimum contact height, and crown surface area from minimum contact height. The novelty of the article is that it improves the fit of individual-tree biomass models by adding crown-related variables and investigates how the accuracy of biomass estimation can be enhanced by using remote sensing methods without obtaining diameter at breast height.
关键词： point cloud data,TLS,effective crown,biomass,crown parameters
更新于2025-09-12 10:27:22
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Three-dimensional point cloud data subtle feature extraction algorithm for laser scanning measurement of large-scale irregular surface in reverse engineering
摘要： In reverse engineering, feature extraction of point cloud data is a key process for the precision machining of the large-sacle complex workpieces. Because of the large numbers of the point cloud data and the difficult recognition of the complex feature, incomplete feature recognition will have a serious impact on the accuracy of the machining. Thus, this paper proposes a subtle feature extraction algorithm, which can be used for the laser scanning measurement of the large-scale irregular surface. First, the L1-median point is calculated as the center point of the neighborhood. Second, the k+1 neighbors are introduced to compute the feature description of the point cloud. Then, the feature is extracted by multi-threshold based on Poisson region growth algorithm. Last, the proposed algorithm is applied to feature extraction experiment of point cloud data for the large spherical crown workpiece. Compared with the traditional algorithms, the proposed algorithm not only can identify the subtle feature information quickly, but also can locate the weld position more accurately.
关键词： Point cloud data,Subtle feature extraction,L1-median,Reverse engineering
更新于2025-09-12 10:27:22
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Extrinsic calibration and kinematic modelling of a laser line triangulation sensor integrated in an intelligent fixture with 3 degrees of freedom
摘要： This article presents the kinematic modelling for the extrinsic calibration of a laser line profile sensor integrated in an intelligent fixture. It aims to characterize the real 3D shape of flexible parts when they are clamped to ensure suitable stiffness for machining processes, aiding to define the machining path to improve the precision of the process. This tool consists of two linear axes and a rotary axis (3 DOF) which enables scanning the area of the part to be processed automatically. In order to carry out the accuracy evaluation of the intelligent fixture, some methods present in the state of the art have been considered and compared. Moreover, in order to design and identify the most suitable calibration procedure a previous simulation process is carried out based on sensitivity analysis. To complete the study, a test piece has been scanned with the intelligent fixture and compared with an external metrological frame employed as a ground truth. In addition, a characterization of the geometric performance of the fixture's linear actuators is carried out to check the geometric performance and its influence on the extrinsic calibration process accuracy. The results of this article show the importance of performing simulation processes in order to define the best measurement scenario for extrinsic calibration. Besides, it demonstrates the influence of the method used to perform extrinsic calibration in order to obtain good precision in the measures, where the geometric performance of the drives have a decisive influence.
关键词： Point cloud processing,Kinematic modelling,Kinematic calibration,Inverse problem,Triangulation sensor
更新于2025-09-12 10:27:22