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Search Results: 1 - 10 of 114912 matches for " ZHANG Yun "
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The Research on QoS Model Design in Mobile Ad Hoc Networks  [PDF]
Yun Zhang
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.511075
Abstract: Wireless Ad Hoc Networks is a special kind of wireless communication network. With the great development of multimedia applications, how to provide QoS guarantee in the MAC layer is the hot topic in wireless ad hoc network (MANET). This paper designed a QoS model in MANET. The feasibility and reliability of this model is analyzed and verified. Compared with the traditional model, the proposed approach is improved in MAC layer in order to achieve high control rate of low-priority transactions.
Geospatial Information Service Based on Ad Hoc Network  [PDF]
Fuling BIAN, Yun ZHANG
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.22013
Abstract: The mobile geospatial information service involves the domain of mobile communication, mobile computing, geospatial information service and other techniques. This paper focuses on the integration of spatial information and mobile communication technologies. The author proposes the architecture of mobile geospatial information service based on the Ad Hoc network. On the basis of this architecture, a system is developed, and applied in correlative fields.
The Analysis of the Structure and Security of Home Control Subnet  [PDF]
Chengyi WANG, Yun ZHANG
Wireless Sensor Network (WSN) , 2009, DOI: 10.4236/wsn.2009.11009
Abstract: A lot of technologies can be used in home control subnet, but the hardware and software resources available for the home control subnet are limited. There are security problems easily seen. The paper gives the system-atic analysis of the structure and function of home control subnet based on the general model of home net-work. The paper has also analyzed two types of major equipment, namely sub-gateways and terminal equip-ment. The major networking technology used in home control subnet is summarized and concluded. In com-bination with relationship among home control subnet, home network, as well as the outside main network, the paper has systematically studied various safety problems related to home control gateways and the possi-ble solutions to those problems have been made.
Segment-Based Terrain Filtering Technique for Elevation-Based Building Detection in VHR Remote Sensing Images  [PDF]
Alaeldin Suliman, Yun Zhang
Advances in Remote Sensing (ARS) , 2016, DOI: 10.4236/ars.2016.53016
Abstract: Building detection in very high resolution (VHR) remote sensing images is crucial for many urban planning and management applications. Since buildings are elevated objects, the incorporation of elevation data provides a mean to reliable detection. However, almost all existing methods of elevation-based building detection must first generate a normalized Digital Surface Model (nDSM). This model is generated by processes of extracting and subtracting terrain elevations from the DSM data. The generation of accurate nDSM is still a challenging task to some extent. This paper introduces a segment-based terrain filtering (SegTF) technique to filter out the terrain elevations directly using DSM elevations. This technique has four steps: elevation co-registration, image segmentation, slope calculation, and building detection. These steps of the developed technique were applied to a dataset that consisted of a VHR image and a corresponding DSM for detecting buildings. The result of the building detection was evaluated and found to be 100% correct with an overall detection quality of 93%. These values indicate a highly reliable and promising technique for mapping buildings in VHR images.
Building Change Detection Improvement Using Topographic Correction Models  [PDF]
Shabnam Jabari, Yun Zhang
Advances in Remote Sensing (ARS) , 2017, DOI: 10.4236/ars.2017.61001
Abstract: In the change detection application of remote sensing, commonly the variation in the brightness values of the pixels/objects in bi-temporal image is used as an indicator for detecting changes. However, there exist effects, other than a change in the objects that can cause variations in the brightness values. One of the effects is the illumination difference on steep surfaces mainly steeproofs of houses in very high resolution images, specifically in off-nadir images. This can introduce the problem of false change detection results. This problem becomes more serious in images with different view-angles. In this study, we propose a methodology to improve the building change detection accuracy using imagery taken under different illumination conditions and different view-angles. This is done by using the Patch-Wise Co-Registration (PWCR) method to overcome the misregistration problem caused by view-angle difference and applying Topographic Correction (TC) methods on pixel intensities to attenuate the effect of illumination angle variation on the building roofs. To select a proper TC method, four of the most widely used correction methods, namely C-correction, Minnaert, Enhanced Minnaert (for slope), and Cosine Correction are evaluated in this study. The results proved that the proposed methodology is capable to improve the change detection accuracy. Specifically, the correction using the C-correction and Enhanced Minnaert improved the change detection accuracy by around 35% in an area with a large number of steep-roof houses imaged under various solar angles.
Optical-Elevation Data Co-Registration and Classification-Based Height Normalization for Building Detection in Stereo VHR Images  [PDF]
Alaeldin Suliman, Yun Zhang
Advances in Remote Sensing (ARS) , 2017, DOI: 10.4236/ars.2017.62008
Abstract: Building detection in very high resolution (VHR) images is crucial for mapping and analysing urban environments. Since buildings are elevated objects, elevation data need to be integrated with images for reliable detection. This process requires two critical steps: optical-elevation data co-registration and aboveground elevation calculation. These two steps are still challenging to some extent. Therefore, this paper introduces optical-elevation data co-registration and normalization techniques for generating a dataset that facilitates elevation-based building detection. For achieving accurate co-registration, a dense set of stereo-based elevations is generated and co-registered to their relevant image based on their corresponding image locations. To normalize these co-registered elevations, the bare-earth elevations are detected based on classification information of some terrain-level features after achieving the image co-registration. The developed method was executed and validated. After implementation, 80% overall-quality of detection result was achieved with 94% correct detection. Together, the developed techniques successfully facilitate the incorporation of stereo-based elevations for detecting buildings in VHR remote sensing images.
Disparity-Based Generation of Line-of-Sight DSM for Image-Elevation Co-Registration to Support Building Detection in Off-Nadir VHR Satellite Images  [PDF]
Alaeldin Suliman, Yun Zhang
Journal of Geographic Information System (JGIS) , 2018, DOI: 10.4236/jgis.2018.101002
Abstract: The integration of optical images and elevation data is of great importance for 3D-assisted mapping applications. Very high resolution (VHR) satellite images provide ideal geo-data for mapping building information. Since buildings are inherently elevated objects, these images need to be co-registered with their elevation data for reliable building detection results. However, accurate co-registration is extremely difficult for off-nadir VHR images acquired over dense urban areas. Therefore, this research proposes a Disparity-Based Elevation Co-Registration (DECR) method for generating a Line-of-Sight Digital Surface Model (LoS-DSM) to efficiently achieve image-elevation data co-registration with pixel-level accuracy. Relative to the traditional photogrammetric approach, the RMSE value of the derived elevations is found to be less than 2 pixels. The applicability of the DECR method is demonstrated through elevation-based building detection (EBD) in a challenging dense urban area. The quality of the detection result is found to be more than 90%. Additionally, the detected objects were geo-referenced successfully to their correct ground locations to allow direct integration with other maps. In comparison to the original LoS-DSM development algorithm, the DECR algorithm is more efficient by reducing the calculation steps, preserving the co-registration accuracy, and minimizing the need for elevation normalization in dense urban areas.
Express Yourself or Stay Mystery? The Effect of Self-Disclosure on Entrepreneurial Identity of Team Members  [PDF]
Yun Duan, Yangyu Zhang, Jingjing Zhang
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.612018
Abstract: The entrepreneurial identity of team members is vital to team stability and entrepreneurial success. How to improve the identity of team members is a significant issue for entrepreneurs to ponder. Combining literature analysis and empirical research, this paper discusses the following issues: 1) Whether the entrepreneur’s self-disclosure has a positive impact on the members’ entrepreneurial identity; 2) The internal mechanism of how entrepreneur’s self-disclosure affects the team members’ entrepreneurial identity. The results show that in the context of entrepreneurship in China, the self-disclosure of entrepreneurs can promote the entrepreneurial identity of the team members, and the entrepreneurial passion mediates the relationship between them.
Analysis of the Systematic Risk of Financial Institution in Modern Finance Evolution
Yun Zhang
International Journal of Economics and Finance , 2010, DOI: 10.5539/ijef.v2n3p234
Abstract: Starting from the resourcing of credit, the instability of financial institution induced by the behaviors of financial institution is analyzed in this article, and the source of the systematic risk is proposed, which indicates that the change of the international monetary system is very important for the stable management of financial institution. Keywords: Credit, Financial institution, Systematic risk
Study on the Innovational Function of the Management
Yun Zhang
International Journal of Business and Management , 2009, DOI: 10.5539/ijbm.v4n6p147
Abstract: Traditional management process summarization should be improved in adapting and instructing the diversified management for modern enterprises, and Chinese enterprises at the present stage also urgently need the new understanding for the management function. Starting from the cognition and practice of the management, the innovation should be the core function of the management, and it should be embodied in the function of the management.
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