Submarine landslides can cause severe damage to marine engineering structures. Their sliding velocity and runout distance are two major parameters for quantifying and analyzing the risk of submarine landslides.Current...Submarine landslides can cause severe damage to marine engineering structures. Their sliding velocity and runout distance are two major parameters for quantifying and analyzing the risk of submarine landslides.Currently, commercial calculation programs such as BING have limitations in simulating underwater soil movements. All of these processes can be consistently simulated through a smoothed particle hydrodynamics（SPH） depth integrated model. The basis of the model is a control equation that was developed to take into account the effects of soil consolidation and erosion. In this work, the frictional rheological mode has been used to perform a simulation study of submarine landslides. Time-history curves of the sliding body＇s velocity, height,and length under various conditions of water depth, slope gradient, contact friction coefficient, and erosion rate are compared; the maximum sliding distance and velocity are calculated; and patterns of variation are discussed.The findings of this study can provide a reference for disaster warnings and pipeline route selection.展开更多
In order to improve depth extraction accuracy, a method using moving array lenslet technique(MALT) in pickup stage is proposed, which can decrease the depth interval caused by pixelation. In this method, the lenslet a...In order to improve depth extraction accuracy, a method using moving array lenslet technique(MALT) in pickup stage is proposed, which can decrease the depth interval caused by pixelation. In this method, the lenslet array is moved along the horizontal and vertical directions simultaneously for N times in a pitch to get N sets of elemental images. Computational integral imaging reconstruction method for MALT is taken to obtain the slice images of the 3 D scene, and the sum modulus(SMD) blur metric is taken on these slice images to achieve the depth information of the 3 D scene. Simulation and optical experiments are carried out to verify the feasibility of this method.展开更多
This paper assesses the sediment load of the glacier fed Langtang River, Nepal from April 2014 to March 2015. Water samples were collected from the centre of the river with a frequency of two samples per each sampling...This paper assesses the sediment load of the glacier fed Langtang River, Nepal from April 2014 to March 2015. Water samples were collected from the centre of the river with a frequency of two samples per each sampling day using the Depth Integration Technique (DIT) on daily basis in the monsoon season, weekly in the pre- and post-monsoon seasons and bi-monthly in the winter season. Suspended sediment concentration (SSC) is calculated from the water samples using filtration followed by oven-drying, and a rating curve is used to calculate daily discharge of the Langtang River. The annual sediment yield is 109,276.75 tons and 37.69, 11.52 and 5.54 tons of sediment is transported per day in the pre-monsoon, post-monsoon and winter seasons, respectively. There is a very high value of 872.86 tons per day in the monsoon season, which contributes the highest sediment load among all of the seasons comprising 83% of the total sediment transport. Diurnal cycle of sediment discharge is clearly seen with higher sediment discharge during the evening than the morning and reaching maximum values of 41.1 kg·s<sup>-1</sup> and 61.5 kg·s<sup>-1</sup>, respectively. A clock-wise hysteresis loop has been obtained for discharge and sediment discharge where sediment flux is higher in the early monsoon than in the late monsoon for a corresponding discharge.展开更多
Aiming at the problem that the draft-position integrated tillage depth control method with fixed comprehensive coefficient of tractor electro-hydraulic hitch system is difficult to adapt to the working environment wit...Aiming at the problem that the draft-position integrated tillage depth control method with fixed comprehensive coefficient of tractor electro-hydraulic hitch system is difficult to adapt to the working environment with large changes in soil conditions,a tractor draft-position integrated tillage depth control method with variable comprehensive coefficient was proposed.A comprehensive coefficient control scheme based on traction resistance was designed and its working principle was clarified.Aiming at the time-varying tillage depth control system,a tillage depth control algorithm based on the sliding mode control with a differential observer was designed.In order to verify the performance of the control scheme,a control system simulation model and a bench test platform were built,and the performance was compared with the draft-position integrated control method with a fixed comprehensive coefficient of 0.5.The results showed that the variable comprehensive coefficient tillage depth control method can automatically adjust the comprehensive coefficient according to the change of soil conditions,and has higher traction efficiency.In the small resistance range,it can better ensure the quality of operation;in the large resistance range,it can ensure the engine performance and protect the tractor from damage.This method is more adaptable to the complex field operation environment,which provides a reference for the research of tillage depth control method.展开更多
We introduce a phase-only hologram generation method based on an integral imaging, and propose an enhancement method in representable depth interval. The computational integral imaging reconstruction method is modifie...We introduce a phase-only hologram generation method based on an integral imaging, and propose an enhancement method in representable depth interval. The computational integral imaging reconstruction method is modified based on optical flow to obtain depth-slice images for the focused objects only. A phaseonly hologram for＇ multiple plane images is generated using the iterative Fresnel transform algorithm. In addition, a division method in hologram plane is proposed for enhancement in the representable minimum depth interval.展开更多
基金The Specialized Research Fund for the Doctoral Program of Higher Education under contract No.20120041130002the National Key Project of Science and Technology under contract No.2011ZX 05056-001-02the Fundamental Research Funds for the Central Universities under contract No.DUT14ZD220
文摘Submarine landslides can cause severe damage to marine engineering structures. Their sliding velocity and runout distance are two major parameters for quantifying and analyzing the risk of submarine landslides.Currently, commercial calculation programs such as BING have limitations in simulating underwater soil movements. All of these processes can be consistently simulated through a smoothed particle hydrodynamics（SPH） depth integrated model. The basis of the model is a control equation that was developed to take into account the effects of soil consolidation and erosion. In this work, the frictional rheological mode has been used to perform a simulation study of submarine landslides. Time-history curves of the sliding body＇s velocity, height,and length under various conditions of water depth, slope gradient, contact friction coefficient, and erosion rate are compared; the maximum sliding distance and velocity are calculated; and patterns of variation are discussed.The findings of this study can provide a reference for disaster warnings and pipeline route selection.
基金supported by the National Natural Science Foundation of China(Nos.11474169 and 61675100)the Tianjin Natural Science Foundation(No.15JCYBJC16900)
文摘In order to improve depth extraction accuracy, a method using moving array lenslet technique(MALT) in pickup stage is proposed, which can decrease the depth interval caused by pixelation. In this method, the lenslet array is moved along the horizontal and vertical directions simultaneously for N times in a pitch to get N sets of elemental images. Computational integral imaging reconstruction method for MALT is taken to obtain the slice images of the 3 D scene, and the sum modulus(SMD) blur metric is taken on these slice images to achieve the depth information of the 3 D scene. Simulation and optical experiments are carried out to verify the feasibility of this method.
文摘This paper assesses the sediment load of the glacier fed Langtang River, Nepal from April 2014 to March 2015. Water samples were collected from the centre of the river with a frequency of two samples per each sampling day using the Depth Integration Technique (DIT) on daily basis in the monsoon season, weekly in the pre- and post-monsoon seasons and bi-monthly in the winter season. Suspended sediment concentration (SSC) is calculated from the water samples using filtration followed by oven-drying, and a rating curve is used to calculate daily discharge of the Langtang River. The annual sediment yield is 109,276.75 tons and 37.69, 11.52 and 5.54 tons of sediment is transported per day in the pre-monsoon, post-monsoon and winter seasons, respectively. There is a very high value of 872.86 tons per day in the monsoon season, which contributes the highest sediment load among all of the seasons comprising 83% of the total sediment transport. Diurnal cycle of sediment discharge is clearly seen with higher sediment discharge during the evening than the morning and reaching maximum values of 41.1 kg·s<sup>-1</sup> and 61.5 kg·s<sup>-1</sup>, respectively. A clock-wise hysteresis loop has been obtained for discharge and sediment discharge where sediment flux is higher in the early monsoon than in the late monsoon for a corresponding discharge.
基金National Key Research and Development Plan of China(Grant No.2022YFD2001202)The Open Project of the State Key Laboratory of Intelligent Agricultural Power Equipment(SKLIAPE2023019)The Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX22_0716).
文摘Aiming at the problem that the draft-position integrated tillage depth control method with fixed comprehensive coefficient of tractor electro-hydraulic hitch system is difficult to adapt to the working environment with large changes in soil conditions,a tractor draft-position integrated tillage depth control method with variable comprehensive coefficient was proposed.A comprehensive coefficient control scheme based on traction resistance was designed and its working principle was clarified.Aiming at the time-varying tillage depth control system,a tillage depth control algorithm based on the sliding mode control with a differential observer was designed.In order to verify the performance of the control scheme,a control system simulation model and a bench test platform were built,and the performance was compared with the draft-position integrated control method with a fixed comprehensive coefficient of 0.5.The results showed that the variable comprehensive coefficient tillage depth control method can automatically adjust the comprehensive coefficient according to the change of soil conditions,and has higher traction efficiency.In the small resistance range,it can better ensure the quality of operation;in the large resistance range,it can ensure the engine performance and protect the tractor from damage.This method is more adaptable to the complex field operation environment,which provides a reference for the research of tillage depth control method.
基金supported by the Brain Korea 21 Program (Information Technology of Seoul National University)
文摘We introduce a phase-only hologram generation method based on an integral imaging, and propose an enhancement method in representable depth interval. The computational integral imaging reconstruction method is modified based on optical flow to obtain depth-slice images for the focused objects only. A phaseonly hologram for＇ multiple plane images is generated using the iterative Fresnel transform algorithm. In addition, a division method in hologram plane is proposed for enhancement in the representable minimum depth interval.
