The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform

Yandong Zhao - One of the best experts on this subject based on the ideXlab platform.

  • A Novel Sensor for Noninvasive Detection of In Situ Stem Water Content Based on Standing Wave Ratio
    Journal of Sensors, 2019
    Co-Authors: Chao Gao, Yue Zhao, Yandong Zhao
    Abstract:

    Stem water content (StWC = volume of water : volume of stem) is an important physiological parameter for vascular plants. And a better underStanding of StWC contributes to solving some research hotspots in forestry, such as drought resistance, cold resistance, precise irrigation, and health assessment. However, there are few noninvasive, in situ, real-time, safe, and low-cost methods for detecting StWC of woody plants. This article presents a novel sensor for noninvasive detection of in situ StWC based on Standing Wave Ratio. Moreover, extensive experiments were conducted to analyze the performance of this sensor including sensitive distance, measuring range, influence factors, and measuring accuracy. The experimental results show that the sensitive distance of StWC sensor is approximately 53 mm in axial direction and 20 mm in radial direction with the measuring range from 0.01 to 1.00 cm3 cm-3. The combined effects of stem EC and temperature on sensor output are significant and it is necessary to correct the error caused by the two factors. Compared with the oven-drying method, StWC sensor has higher measuring accuracy than Testo 606-2 which is a sensor for measuring wood water content and its average error is less than 0.01 cm3 cm-3. In addition, StWC sensor performed very well on the crape myrtle with high sensitivity equal to 1022.1 mV (cm3 cm-3)-1 and measuring results also accorded with the diurnal dynamics of stem water content.

  • Determining Forest Duff Water Content Using a Low-Cost Standing Wave Ratio Sensor.
    Sensors (Basel Switzerland), 2018
    Co-Authors: Xiaofei Yan, Zhao Yajie, Qiang Cheng, Xiaoliang Zheng, Yandong Zhao
    Abstract:

    Forest duff (fermentation and humus) water content is an important parameter for fire risk prediction and water resource management. However, accurate determination of forest duff water content is difficult due to its loose structure. This study evaluates the feasibility of a Standing Wave Ratio (SWR) sensor to accurately determine the forest duff water content. The performance of this sensor was tested on fermentation and humus with eight different compaction levels. Meanwhile, a commercialized time domain reflectometry (TDR) was employed for comparison. CalibRation results showed that there were strong linear relationships between the volumetric water content (θV) and the SWR sensor readings (VSWR) at different compaction classes for both fermentation and humus samples. The sensor readings of both SWR and TDR underestimated the forest duff water content at low compacted levels, proving that the compaction of forest duff could significantly affect the measurement accuracy of both sensors. Experimental data also showed that the accuracy of the SWR sensor was higher than that of TDR according to the root mean square error (RMSE). Furthermore, low cost is another important advantage of the SWR sensor in comparison with TDR. This low-cost SWR sensor performs well in loose materials and is feasible for evaluating the water content of forest duff. In addition, the results indicate that decomposition of the forest duff should be taken into account for continuous and long-term water content measurement.

  • Notice of Retraction Measuring plant stem water content by Standing-Wave Ratio
    2010 3rd International Conference on Computer Science and Information Technology, 2010
    Co-Authors: Yandong Zhao, Peijin Hu, Hailan Wang
    Abstract:

    This For the determination of plant water content on-line, a sensor based on SWR (Standing-Wave Ratio) measurement principle was developed. To evaluate the feasibility of the proposed technique, a comparative experiment between the developed sensor (BD-II sensor) and SF-L (SF Type Sap Flow Systems, Germany) has been conducted over the past two years. The experimental results obtained from both instruments show a good agreement (R2=0.76). Therefore, the proposed technique is a promising tool in dynamically monitoring plant stem water.

  • Measuring water content variations in stems by Standing Wave Ratio principle
    2010 IEEE International Conference on Mechatronics and Automation, 2010
    Co-Authors: Hailan Wang, Yandong Zhao
    Abstract:

    The sensor measuring stem water content based on SWR (Standing Wave Ratio) principle was presented in this paper. Laboratory and field tests were performed to examine the feasibility of SWR (Standing Wave Ratio) sensor to monitor changes in the moisture storage of the woody parts of trees. To serve as Wave guides for the SWR signal, pairs stainless steel rods (50mm long, 3mm in diameter, and 30mm sepaRation) were driven into parallel pilot holes drilled into woody parts of trees, and a cable testing oscilloscope was used to determine the output voltage of the transmission line. A laboratory calibRation test was performed on two sapwood samples, so that the relation between the volumetric water content and the output voltage could be determined over a range of water contents. At the same time, root-zone soil water content was measured to evaluate the root-zone environment of the tree.

Hailan Wang - One of the best experts on this subject based on the ideXlab platform.

  • Notice of Retraction Measuring plant stem water content by Standing-Wave Ratio
    2010 3rd International Conference on Computer Science and Information Technology, 2010
    Co-Authors: Yandong Zhao, Peijin Hu, Hailan Wang
    Abstract:

    This For the determination of plant water content on-line, a sensor based on SWR (Standing-Wave Ratio) measurement principle was developed. To evaluate the feasibility of the proposed technique, a comparative experiment between the developed sensor (BD-II sensor) and SF-L (SF Type Sap Flow Systems, Germany) has been conducted over the past two years. The experimental results obtained from both instruments show a good agreement (R2=0.76). Therefore, the proposed technique is a promising tool in dynamically monitoring plant stem water.

  • Measuring water content variations in stems by Standing Wave Ratio principle
    2010 IEEE International Conference on Mechatronics and Automation, 2010
    Co-Authors: Hailan Wang, Yandong Zhao
    Abstract:

    The sensor measuring stem water content based on SWR (Standing Wave Ratio) principle was presented in this paper. Laboratory and field tests were performed to examine the feasibility of SWR (Standing Wave Ratio) sensor to monitor changes in the moisture storage of the woody parts of trees. To serve as Wave guides for the SWR signal, pairs stainless steel rods (50mm long, 3mm in diameter, and 30mm sepaRation) were driven into parallel pilot holes drilled into woody parts of trees, and a cable testing oscilloscope was used to determine the output voltage of the transmission line. A laboratory calibRation test was performed on two sapwood samples, so that the relation between the volumetric water content and the output voltage could be determined over a range of water contents. At the same time, root-zone soil water content was measured to evaluate the root-zone environment of the tree.

Weizhong Yang - One of the best experts on this subject based on the ideXlab platform.

  • CCTA - Soil Water Sensor Based on Standing Wave Ratio Method of Design and Development
    Computer and Computing Technologies in Agriculture VIII, 2015
    Co-Authors: Xu Yinli, Weizhong Yang
    Abstract:

    Soil moisture is one of the most important parameters in the soil properties, the traditional methods of soil moisture measurement is time-consuming. And it can’t meet the soil moisture measurement’s real-time and fast requirements. This paper analyzes the relationship between soil moisture and its dielectric properties, research the Standing Wave Ratio method for measuring soil water content. Firstly, design hardware circuit, plate making, and welding circuit board, then insert the probe into the soil, by measuring the reflection coefficient, we can know the probe impedance which depend on the soil dielectric constant. At last we can find the internal relation between output voltage and soil water content, by measuring the multiple sets of different water content of soil.

  • Soil Water Sensor Based on Standing Wave Ratio Method of Design and Development
    2014
    Co-Authors: Weizhong Yang
    Abstract:

    Soil moisture is one of the most important parameters in the soil properties, the traditional methods of soil moisture measurement is time-consuming. And it can’t meet the soil moisture measurement’s real-time and fast requirements. This paper analyzes the relationship between soil moisture and its dielectric properties, research the Standing Wave Ratio method for measuring soil water content. Firstly, design hardware circuit, plate making, and welding circuit board, then insert the probe into the soil, by measuring the reflection coefficient, we can know the probe impedance which depend on the soil dielectric constant. At last we can find the internal relation between output voltage and soil water content, by measuring the multiple sets of different water content of soil.

Wei Zhen - One of the best experts on this subject based on the ideXlab platform.

  • a novel high frequency voltage Standing Wave Ratio based grounding electrode line fault supervision in ultra high voltage dc transmission systems
    Energies, 2017
    Co-Authors: Yufei Teng, Xiaopeng Li, Qi Huang, Yifei Wang, Shi Jing, Zhenchao Jiang, Wei Zhen
    Abstract:

    In order to improve the fault monitoring performance of grounding electrode lines in ultra-high voltage DC (UHVDC) transmission systems, a novel fault monitoring approach based on the high-frequency voltage Standing-Wave Ratio (VSWR) is proposed in this paper. The VSWR is defined considering a lossless transmission line, and the characteristics of the VSWR under different conditions are analyzed. It is shown that the VSWR equals 1 when the terminal resistance completely matches the characteristic impedance of the line, and when a short circuit fault occurs on the grounding electrode line, the VSWR will be greater than 1. The VSWR will approach positive infinity under metallic earth fault conditions, whereas the VSWR in non-metallic earth faults will be smaller. Based on these analytical results, a fault supervision criterion is formulated. The effectiveness of the proposed VSWR-based fault supervision technique is verified with a typical UHVDC project established in Power Systems Computer Aided Design/Electromagnetic Transients including DC(PSCAD/EMTDC). Simulation results indicate that the proposed strategy can reliably identify the grounding electrode line fault and has strong anti-fault resistance capability.

Yufei Teng - One of the best experts on this subject based on the ideXlab platform.

  • a novel high frequency voltage Standing Wave Ratio based grounding electrode line fault supervision in ultra high voltage dc transmission systems
    Energies, 2017
    Co-Authors: Yufei Teng, Xiaopeng Li, Qi Huang, Yifei Wang, Shi Jing, Zhenchao Jiang, Wei Zhen
    Abstract:

    In order to improve the fault monitoring performance of grounding electrode lines in ultra-high voltage DC (UHVDC) transmission systems, a novel fault monitoring approach based on the high-frequency voltage Standing-Wave Ratio (VSWR) is proposed in this paper. The VSWR is defined considering a lossless transmission line, and the characteristics of the VSWR under different conditions are analyzed. It is shown that the VSWR equals 1 when the terminal resistance completely matches the characteristic impedance of the line, and when a short circuit fault occurs on the grounding electrode line, the VSWR will be greater than 1. The VSWR will approach positive infinity under metallic earth fault conditions, whereas the VSWR in non-metallic earth faults will be smaller. Based on these analytical results, a fault supervision criterion is formulated. The effectiveness of the proposed VSWR-based fault supervision technique is verified with a typical UHVDC project established in Power Systems Computer Aided Design/Electromagnetic Transients including DC(PSCAD/EMTDC). Simulation results indicate that the proposed strategy can reliably identify the grounding electrode line fault and has strong anti-fault resistance capability.