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An improved algorithm based on equivalent sound velocity profile method at large incident angle
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作者 Qianqian Li Qian Tong +3 位作者 Fanlin Yang Qi Li Zhihao Juan Yu Luo 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2024年第2期161-167,共7页
With the development of ultra-wide coverage technology,multibeam echo-sounder(MBES)system has put forward higher requirements for localization accuracy and computational efficiency of ray tracing method.The classical ... With the development of ultra-wide coverage technology,multibeam echo-sounder(MBES)system has put forward higher requirements for localization accuracy and computational efficiency of ray tracing method.The classical equivalent sound speed profile(ESSP)method replaces the measured sound velocity profile(SVP)with a simple constant gradient SVP,reducing the computational workload of beam positioning.However,in deep-sea environment,the depth measurement error of this method rapidly increases from the central beam to the edge beam.By analyzing the positioning error of the ESSP method at edge beam,it is discovered that the positioning error increases monotonically with the incident angle,and the relationship between them could be expressed by polynomial function.Therefore,an error correction algorithm based on polynomial fitting is obtained.The simulation experiment conducted on an inclined seafloor shows that the proposed algorithm exhibits comparable efficiency to the original ESSP method,while significantly improving bathymetry accuracy by nearly eight times in the edge beam. 展开更多
关键词 equivalent sound speed profile ray tracing method large incident angle edge beam deep sea error correction multibeam echo-sounder system
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An Effective Method to Determine the Distribution Boundary of Cobalt-Rich Fe-Mn Crusts on a Guyot: Synchronous Application of Sub-bottom Profiling and Deep-Sea Video Recording 被引量:3
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作者 HeGaowen LiangDonghong +4 位作者 SongChengbin SunXiaoming WuShuigen ZhouJianping ZhangXuehua 《Journal of China University of Geosciences》 SCIE CSCD 2005年第2期178-182,共5页
Determining the upper boundary of the cobalt-rich crust distribution of a guyot is important for estimating the mineral resources available, however, it has also long been an unsolved question. Correlations between th... Determining the upper boundary of the cobalt-rich crust distribution of a guyot is important for estimating the mineral resources available, however, it has also long been an unsolved question. Correlations between the sub-bottom structures, revealed by sub-bottom profiling, and crust distribution can be revealed for the first time by the synchronous application of sub-bottom profiling and deep-sea video recording. The lower boundary of the sediment corresponds with the upper boundary of the crust. By analysis of these two kinds of data, the lower boundary of the sediment can be determined; therefore, the upper boundary of the crust distribution can be deduced. According to this method of analysis, the upper boundary of water depth of crust distribution of a seamount in the western Pacific is about 1 560 m. 展开更多
关键词 sub-bottom profiling deep-sea video recording guyot cobalt-rich ferromanganese crust distribution boundary
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Elimination of Wind Wave Effects on Sub-Bottom Profiler Record
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作者 刘秀娟 高抒 杨旸 《China Ocean Engineering》 SCIE EI 2007年第2期355-362,共8页
With the presence of wind waves, the swaying of survey vessel may effect the quality of sub-bottom profiler records and, therefore, it is necessary to correct the distortions induced by wave action. A major issue is t... With the presence of wind waves, the swaying of survey vessel may effect the quality of sub-bottom profiler records and, therefore, it is necessary to correct the distortions induced by wave action. A major issue is to distinguish wind wave effect and real bedforms such as sand waves. In this paper, a bandstop filter is designed according to the frequency features of wind wave effect to treat the distortion of seabed topography by wind waves. The technique is used to correct the sub-bottom profile in order to eliminate the wave-induced distortions for the sub-bottom profile records from the Yangtze Estuary. This study shows that the undulate seabed record is resulted from wave action, rather than the presence of sand waves, and the filtration technique helps to eliminate the wave effect and recover the real morphology of seabed and the sediment sequence underneath. In addition, a method for data processing is proposed for the case that the record indeed represents a combination of wave effects and real bedforms. 展开更多
关键词 sub-bottom profiler wind wave effect filtering method Yangtze Estuary
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Calculation and Analysis of TVMS Considering Profile Shifts and Surface Wear Evolution Process of Spur Gear
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作者 Wenzheng Liu Rupeng Zhu +1 位作者 Wenguang Zhou Jingjing Wang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第3期136-150,共15页
Profile shift is a highly effective technique for optimizing the performance of spur gear transmission systems.However,tooth surface wear is inevitable during gear meshing due to inadequate lubrication and long-term o... Profile shift is a highly effective technique for optimizing the performance of spur gear transmission systems.However,tooth surface wear is inevitable during gear meshing due to inadequate lubrication and long-term operation.Both profile shift and tooth surface wear(TSW)can impact the meshing characteristics by altering the involute tooth profile.In this study,a tooth stiffness model of spur gears that incorporates profile shift,TSW,tooth deformation,tooth contact deformation,fillet-foundation deformation,and gear body structure coupling is established.This model efficiently and accurately determines the time-varying mesh stiffness(TVMS).Additionally,an improved wear depth prediction method for spur gears is developed,which takes into consideration the mutually prime teeth numbers and more accurately reflects actual gear meshing conditions.Results show that consideration of the mutual prime of teeth numbers will have a certain impact on the TSW process.Furthermore,the finite element method(FEM)is employed to accurately verify the values of TVMS and load sharing ratio(LSR)of profile-shifted gears and worn gears.This study quantitatively analyzes the effect of profile shift on the surface wear process,which suggests that gear profile shift can partially alleviate the negative effects of TSW.The contribution of this study provides valuable insights into the design and maintenance of spur gear systems. 展开更多
关键词 profile shift Tooth surface wear Structure coupling effect Improved wear depth prediction method TVMS
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Methods to Improve the Long Distance Time-Varying Channel Transmission Performance of Expendable Profiler
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作者 ZHENG Yu ZHANG Xiao-yang +2 位作者 WANG Xiao-rui GUO Xing-xin LI Hong-zhi 《China Ocean Engineering》 SCIE EI CSCD 2019年第6期753-761,共9页
To improve the transmission performance of XCTD channel, this paper proposes a method to measure directly and fit the channel transmission characteristics by using frequency sweeping method. Sinusoidal signals with a ... To improve the transmission performance of XCTD channel, this paper proposes a method to measure directly and fit the channel transmission characteristics by using frequency sweeping method. Sinusoidal signals with a frequency range of 100 Hz to 10 k Hz and an interval of 100 Hz are used to measure transmission characteristics of channels with lengths of 300 m, 800 m, 1300 m, and 1800 m. The correctness of the fitted channel characteristics by transmitting square wave, composite waves of different frequencies, and ASK modulation are verified. The results show that when the frequency of the signal is below 1500 Hz, the channel has very little effect on the signal. The signal compensated for amplitude and phase at the receiver is not as good as the uncompensated signal.Alternatively, when the signal frequency is above 1500 Hz, the channel distorts the signal. The quality of signal compensated for amplitude and phase at receiver is better than that of the uncompensated signal. Thus, we can select the appropriate frequency for XCTD system and the appropriate way to process the received signals. Signals below1500 Hz can be directly used at the receiving end. Signals above 1500 Hz are used after amplitude and phase compensation at the receiving end. 展开更多
关键词 expandable conductivity temperature depth(XCTD)profiler time-varying channel modeling frequency sweeping method amplitude and phase compensation transmission performance
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Tooth surface geometry optimization of spiral bevel and hypoid gears generated by duplex helical method with circular profile blade 被引量:12
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作者 张宇 严宏志 +1 位作者 曾韬 曾亦愚 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第3期544-554,共11页
In order to effectively improve meshing performance of spiral bevel and hypoid gears generated by the duplex helical method, the effects of straight lined and circular cutting edges profile on meshing and contact of s... In order to effectively improve meshing performance of spiral bevel and hypoid gears generated by the duplex helical method, the effects of straight lined and circular cutting edges profile on meshing and contact of spiral bevel and hypoid gears were investigated analytically. Firstly, a mathematical model of spiral bevel and hypoid gears with circular blade profile was established according to the cutting characteristics of the duplex helical method. Based on a hypoid gear drive, the tooth bearings and the functions of transmission errors of four design cases were analyzed respectively by the use of the tooth contact analysis(TCA), and the contact stresses of the four design cases were analyzed and compared using simulation software. Finally, the curvature radius of the circular profile blade was optimized. The results show that the contact stresses are availably reduced, and the areas of edge contact and severe contact stresses can be avoided by selecting appropriate circular blade profile. In addition, the convex and concave sides are separately modified by the use of different curvature radii of inside and outside blades, which can increase the flexibility of the duplex helical method. 展开更多
关键词 circular blade profile duplex helical method spiral bevel and hypoid gears modification contact stress
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Calibration of Soil Electromagnetic Conductivity in Inverted Salinity Profiles with an Integration Method 被引量:9
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作者 YAO Rong-Jian YANG Jin-Song LIU Guang-Ming 《Pedosphere》 SCIE CAS CSCD 2007年第2期246-256,共11页
Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity (ECa) and soil electrical conductivity of a saturated soil paste extract (ECe) or a 1:5 soil water e... Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity (ECa) and soil electrical conductivity of a saturated soil paste extract (ECe) or a 1:5 soil water extract (EC1:5) using an electromagnetic induction instrument (EM38). The modeled coefficients, one of the successful and classical methods hitherto, were chosen to calibrate the EM38 measurements of the inverted salinity profiles of characteristic coastal saline soils at selected sites of Xincao Farm, Jiangsu Province, China. However, this method required three parameters for each depth layer. An integration approach, based on an exponential decay profile model, was proposed and the model was fitted to all the calibration sites. The obtained model can then be used to predict EC1:5 at a certain depth from electromagnetic measurements made using the EM38 device positioned in horizontal and vertical positions at the soil surface. This exponential decay model predicted the EC1:5 well according to the results of a one-way analysis of variance, and the further comparison indicated that the modeled coefficients appeared to be slightly superior to, but not statistically different from, this exponential decay model. Nevertheless, this exponential decay model was more significant and practical because it depended on less empirical parameters and could be used to perform point predictions of EC1:5 continuously with depth. 展开更多
关键词 coastal saline soils electromagnetic conductivity exponential decay model integration calibration method inverted salinity profiles
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Sound propagation in inhomogeneous waveguides with sound-speed profiles using the multimodal admittance method 被引量:1
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作者 Qi Li Juan Liu Wei Guo 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第1期346-356,共11页
The multimodal admittance method and its improvement are presented to deal with various aspects in underwater acoustics,mostly for the sound propagation in inhomogeneous waveguides with sound-speed profiles,arbitrary-... The multimodal admittance method and its improvement are presented to deal with various aspects in underwater acoustics,mostly for the sound propagation in inhomogeneous waveguides with sound-speed profiles,arbitrary-shaped liquid-like scatterers,and range-dependent environments.In all cases,the propagation problem governed by the Helmholtz equation is transformed into initial value problems of two coupled first-order evolution equations with respect to the modal components of field quantities(sound pressure and its derivative),by projecting the Helmholtz equation on a constructed orthogonal and complete local basis.The admittance matrix,which is the modal representation of Direchlet-to-Neumann operator,is introduced to compute the first-order evolution equations with no numerical instability caused by evanescent modes.The fourth-order Magnus scheme is used for the numerical integration of differential equations in the numerical implementation.The numerical experiments of sound field in underwater inhomogeneous waveguides generated by point sources are performed.Besides,the numerical results computed by simulation software COMSOL Multiphysics are given to validate the correction of the multimodal admittance method.It is shown that the multimodal admittance method is an efficient and stable numerical method to solve the wave propagation problem in inhomogeneous underwater waveguides with sound-speed profiles,liquid-like scatterers,and range-dependent environments.The extension of the method to more complicated waveguides such as horizontally stratified waveguides is available. 展开更多
关键词 inhomogeneous waveguide multimodal admittance method sound-speed profiles admittance matrix
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2 kHz High Power Smart Transducer for Acoustic Sub-bottom Profiling Applications 被引量:1
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作者 R. Sathishkumar 《Journal of Marine Science and Application》 2013年第3期361-365,共5页
In this study,a 2kHz Tonpilz projector was designed using a Terfenol-D and modeled in ATILA.For the purpose of modeling studies,it has been determined that a radiating head mass exhibits better transmitting current re... In this study,a 2kHz Tonpilz projector was designed using a Terfenol-D and modeled in ATILA.For the purpose of modeling studies,it has been determined that a radiating head mass exhibits better transmitting current response(TCR) at 136 mm diameter,where the resonance occurs at 2.4kHz and the peak value of 118 dB re 1 μPa/A at 1 m occurs at 12 kHz.Also bolt at a 46mm distance from the center of the head mass offers resonance at 2.4kHz,and the peak value of 115.3 dB re 1 μPa/A at 1m occurs at 11.5kHz.This optimized design is fabricated and molded with polyurethane of 3mm thickness.The prototype was tested at the Acoustic Test Facility(ATF) of National Institute of Ocean Technology(NIOT) for its underwater performances.Based on the result,the fundamental resonance was determined to be 2.18kHz and the peak value of TCR of 182 dB re 1 μPa/A at 1m occurs at 14 kHz.The maximum value of the RS was found to be -190 dB re 1V/μPa at 1m at a frequency of 2.1kHz. 展开更多
关键词 smart transducer MAGNETOSTRICTION acoustic sub-bottom profiling transmitting current response(TCR)
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Reconstructing bubble profiles from gas-liquid two-phase flow data using agglomerative hierarchical clustering method 被引量:2
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作者 WU Dong-ling SONG Yan-po +1 位作者 PENG Xiao-qi GAO Dong-bo 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第8期2056-2067,共12页
The knowledge of bubble profiles in gas-liquid two-phase flows is crucial for analyzing the kinetic processes such as heat and mass transfer, and this knowledge is contained in field data obtained by surface-resolved ... The knowledge of bubble profiles in gas-liquid two-phase flows is crucial for analyzing the kinetic processes such as heat and mass transfer, and this knowledge is contained in field data obtained by surface-resolved computational fluid dynamics (CFD) simulations. To obtain this information, an efficient bubble profile reconstruction method based on an improved agglomerative hierarchical clustering (AHC) algorithm is proposed in this paper. The reconstruction method is featured by the implementations of a binary space division preprocessing, which aims to reduce the computational complexity, an adaptive linkage criterion, which guarantees the applicability of the AHC algorithm when dealing with datasets involving either non-uniform or distorted grids, and a stepwise execution strategy, which enables the separation of attached bubbles. To illustrate and verify this method, it was applied to dealing with 3 datasets, 2 of them with pre-specified spherical bubbles and the other obtained by a surface-resolved CFD simulation. Application results indicate that the proposed method is effective even when the data include some non-uniform and distortion. 展开更多
关键词 bubble profile reconstruction gas-liquid two-phase flow clustering method surface-resolved computational fluid dynamics (CFD) distorted bubble shape
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Antimicrobial Profile of Lactic Acid Bacteria Isolated from Vegetables and Indigenous Fermented Foods of India against Clinical Pathogens Using Microdilution Method 被引量:4
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作者 Ami PATEL Nihir SHAH +3 位作者 Padma AMBALAM J. B. PRAJAPATI Olle HOLST Asa LJUNGH 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2013年第9期759-764,共6页
In dairy and food industries lactic acid bacteria (LAB) have been used in form of starter culture that plays vital role in fermentation; as flavouring and texturizing or as preservative agents. There is increasing e... In dairy and food industries lactic acid bacteria (LAB) have been used in form of starter culture that plays vital role in fermentation; as flavouring and texturizing or as preservative agents. There is increasing evidence that lactobacilli which inhabit the gastrointestinal tract develop antimicrobial activities and participate in the host's defence system[1]. During fermentation, most of the LAB produces a number of different compounds like organic acids, hydrogen peroxide, diacetyl, acetaldehyde, carbon dioxide, polysaccharides, and proteinaceous compounds called bacteriocins or bacteriocinogenic peptides. 展开更多
关键词 Antimicrobial profile of Lactic Acid Bacteria Isolated from Vegetables and Indigenous Fermented Foods of India against Clinical Pathogens Using Microdilution method CFS
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A Three-Dimensional Satellite Retrieval Method for Atmospheric Temperature and Moisture Profiles
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作者 张蕾 邱崇践 黄建平 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2008年第5期897-904,共8页
A three-dimensional variational method is proposed to simultaneously retrieve the 3-D atmospheric temperature and moisture profiles from satellite radiance measurements. To include both vertical structure and the hori... A three-dimensional variational method is proposed to simultaneously retrieve the 3-D atmospheric temperature and moisture profiles from satellite radiance measurements. To include both vertical structure and the horizontal patterns of the atmospheric temperature and moisture, an EOF technique is used to decompose the temperature and moisture field in a 3-D space. A number of numerical simulations are conducted and they demonstrate that the 3-D method is less sensitive to the observation errors compared to the 1-D method. When the observation error is more than 2.0 K, to get the best results, the truncation number for the EOF's expansion have to be restricted to 2 in the 1-D method, while it can be set as large as 40 in a 3-D method. This results in the truncation error being reduced and the retrieval accuracy being improved in the 3-D method. Compared to the 1-D method, the rms errors of the 3-D method are reduced by 48% and 36% for the temperature and moisture retrievals, respectively. Using the real satellite measured brightness temperatures at 0557 UTC 31 July 2002, the temperature and moisture profiles are retrieved over a region (20°-45°N, 100°- 125°E) and compared with 37 collocated radiosonde observations. The results show that the retrieval accuracy with a 3-D method is significantly higher than those with the 1-D method. 展开更多
关键词 atmospheric temperature and moisture profile RETRIEVAL EOF three-dimensional method satellite radiance
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Application of Schlumberger transverse profiling method to detecting a strike fault
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作者 吴子泉 王成虎 +2 位作者 谭捍东 冯锐 程久龙 《Acta Seismologica Sinica(English Edition)》 EI CSCD 2006年第1期72-77,共6页
Because it is difficult to detect a strike fault, its physical properties are discussed in this paper. Using physical simulation, numerical modeling and the in situ data, the differences between the apparent resistivi... Because it is difficult to detect a strike fault, its physical properties are discussed in this paper. Using physical simulation, numerical modeling and the in situ data, the differences between the apparent resistivity of low resistivity model obtained by transverse profiling method (TPM) whose electrode array is vertical to the profile and those by longitudinal profiling method (LPM) whose electrode array is parallel to the profile are analyzed, respectively. Our results show that the former has much marked amplitudes of anomaly. Therefore, TPM can be used to detect a strike fault more effectively and locate it more precisely, and is expected to be a new approach for detecting a sliding fault. 展开更多
关键词 strike fault Schlumberger transverse profiling method physical simulation numerical modeling application example
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AN APPROXIMATE METHOD FOR DETERMING THE VELOCITY PROFILE IN A LAMINAR BOUNDARY-LAYER ON FLAT PLATE
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作者 袁镒吾 刘又文 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1999年第4期112-117,共6页
In this paper, using the integration method, it is sought to solve the problem for the laminar boundary_layer on a flat plate. At first, a trial function of the velocity profile which satisfies the basical boundary co... In this paper, using the integration method, it is sought to solve the problem for the laminar boundary_layer on a flat plate. At first, a trial function of the velocity profile which satisfies the basical boundary conditions is selected. The coefficients in the trial function awaiting decision are decided by using some numerical results of the boundary_layer differential equations. It is similar to the method proposed by Peng Yichuan, but the former is simpler. According to the method proposed by Peng, when the awaiting decision coefficients of the trial function are decided, it is sought to solve a third power algebraic equation. On the other hand, in this paper, there is only need for solving a linear algebraic equation. Moreover, the accuracy of the results of this paper is higher than that of Peng. 展开更多
关键词 flat plate laminar flow BOUNDARY_LAYER velocity profile method of weighted residuals (MWR)
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A New Method of Profiling Remote-Sensing Reflectance of Coastal Waters
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作者 李铜基 陈清莲 +1 位作者 汪小勇 杨安安 《Marine Science Bulletin》 CAS 2005年第1期37-44,共8页
The profiling method is the first method to select in measuring the remote-sensing reflectance. In the light of the characteristics of China’s coastal waters, we develop a new method to compensate the environment’s ... The profiling method is the first method to select in measuring the remote-sensing reflectance. In the light of the characteristics of China’s coastal waters, we develop a new method to compensate the environment’s effects with the downwelling (λ)rsi r radiance’s profile and to estimate the underwater remote-sensing reflectance r. (λ)rsT he result indicates that the relative deviation of repetitious r in one station is around 10 %. 展开更多
关键词 profiling method remote-sensing reflectance method
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Study on Design Rainstorm Profile in Liuzhou City Based on Pilgrim &Cordery Method
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作者 Xiaoling Su Dong Xie +5 位作者 Lei Liu Chunrong Liang Zhourong Liu Yu Li Qiu Lan Le Ren 《Journal of Geoscience and Environment Protection》 2019年第3期136-144,共9页
Liuzhou City is located in Guangxi Zhuang Autonomous Region of China. It has a warm and rainy climate and belongs to the middle subtropical monsoon climate. It is a rainstorm and flood-prone area. The work of flood dr... Liuzhou City is located in Guangxi Zhuang Autonomous Region of China. It has a warm and rainy climate and belongs to the middle subtropical monsoon climate. It is a rainstorm and flood-prone area. The work of flood drainage and waterlogging prevention is very important. The “minute to minute” rainfall process data of Liuzhou National Meteorological Observation Station from 1975 to 2014 and the Pilgrim & Cordery method were used to estimate the short-time design rainstorm profile of Liuzhou City, and the profiles of the rainfall lasting for 30, 60, 90, 120, 150, and 180 min were obtained. The research shows that the same rain duration and different recurrence period conditions are consistent with the rainstorm profile. The rainfall duration of 30, 60, 90, 120, and 180 min generally shows single-peak rainstorm profile, and the rainfall duration of 150 min shows double-peak rainstorm profile. Most peaks of each short-time design rainstorm profile are at or ahead of the 1/3 part of the entire rainfall process. During the same recurrence period, the rainfall in peak period fluctuated with the increase of the duration, and the intensity of rainfall increased with the prolonging of the recurrence period. 展开更多
关键词 Liuzhou CITY PILGRIM & Cordery method Short-Time RAINSTORM DESIGN RAINSTORM profilE
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Identification of hidden faults using determining velocity structure profile by spatial autocorrelation method in the west of Mashhad plain(Northeast of Iran)
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作者 Seyedeh Fatemeh NEMATI Naser HAFEZI MOGHADAS +1 位作者 Gholam Reza LASHKARIPOUR Hosein SADEGHI 《Journal of Mountain Science》 SCIE CSCD 2021年第12期3261-3274,共14页
Characterizing the subsurface structure is an important parameter for the improvement of seismic hazard assessment.Due to the tectonic complexity of the earth,some deep fractures do not reach the earth's surface a... Characterizing the subsurface structure is an important parameter for the improvement of seismic hazard assessment.Due to the tectonic complexity of the earth,some deep fractures do not reach the earth's surface and are not detectable with visual analysis.Therefore,the lack of knowledge of faults and fractures can result in disasters,especially in urban planning.Many geophysical methods can be used to estimate subsurface structure characterization.However,a more reliable method is required to assess seismic hazards and reduce potential damage in metropolitan areas without destroying buildings and structures.This paper aims to identify hidden faults and structures using shear wave velocity sections.To do this,surface wave dispersion curve was extracted from the vertical component of microtremor array recording using the spatial autocorrelation(SPAC)method in two profiles and 13 array stations(perpendicular to the altitudes)to obtain shear wave velocity structure(Vs)in the west of Mashhad,northeast of Iran.The results of shear wave velocity profiles(Vs)indicate sudden changes in the thickness of sediments.This can be related to the displacement of a normal fault in this area causing the bottom rock to fall and an increase in the alluvial thickness in the central part of the plain.The velocity in the floor rock is 2000 meters per second in this area.According to the surface outcrops and water wells data,its material is slate and Phyllite metamorphic rocks that are exposed in the adjacent heights.Besides,the seismic profile results were well consistent with electrical resistance data and well logs indicating that the tool array method is flexible,non-invasive,relatively fast,and effective for urban areas with satisfactory accuracy. 展开更多
关键词 Subsurface Structure Hidden Fault Array Microtremor SPAC method Vs profile Mashhad Seismic hazard assessment
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Effect of layer thickness and voxel size inversion on leaf area density based on the voxel-based canopy profiling method
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作者 Yan Chen Jian Liu +5 位作者 Xiong Yao Yangbo Deng Zhenbang Hao Lingchen Lin Nankun Wu Kunyong Yu 《Journal of Forestry Research》 SCIE CAS CSCD 2022年第5期1545-1558,共14页
Voxel-based canopy profiling is commonly used to determine small-scale leaf area.Layer thickness and voxel size impact accuracy when using this method.Here,we determined the optimal combination of layer thickness and ... Voxel-based canopy profiling is commonly used to determine small-scale leaf area.Layer thickness and voxel size impact accuracy when using this method.Here,we determined the optimal combination of layer thickness and voxel size to estimate leaf area density accurately.Terrestrial LiDAR Stonex X300 was used to generate point cloud data for Masson pines(Pinus massoniana).The canopy layer was stratified into 0.10-1.00-m-thick layers,while voxel size was 0.01-0.10 m.The leaf area density of individual trees was estimated using leaf area indices for the upper,middle,and lower canopy and the overall canopy.The true leaf area index,obtained by layered harvesting,was used to verify the inversion results.Leaf area density was inverted by nine combinations of layer thickness and voxel size.The average relative accuracy and mean estimated accuracy of these combined inversion results exceeded 80%.When layer thickness was 1.00 m and voxel size 0.05 m,inversion was closest to the true value.The average relative accuracy was 92.58%,mean estimated accuracy 98.00%,and root mean square error 0.17.The combination of leaf area density and index was accurately retrieved.In conclusion,nondestructive voxel-based canopy profiling proved suitable for inverting the leaf area density of Masson pine in Hetian Town,Fujian Province. 展开更多
关键词 Terrestrial LiDAR Leaf area density Pinus massoniana Voxel-based canopy profiling method Layer thickness Voxel size
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Profile Method for Measuring Apparent Optical Parameters (AOP) Ⅱin Class- Waters
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作者 李铜基 陈清莲 《Marine Science Bulletin》 CAS 2004年第1期1-8,共8页
The profile method is the principal method first to be chosen to measure the apparent optical parameters of waters. This paper first introduces the profile method briefly, then modifies Ⅱthe applied algorithm in the ... The profile method is the principal method first to be chosen to measure the apparent optical parameters of waters. This paper first introduces the profile method briefly, then modifies Ⅱthe applied algorithm in the light of the properties of the class- waters and lastly, analyses the effect of application. 展开更多
关键词 profile method apparent optical parameters class- waters
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Study on Design Rainstorm Profile in Liuzhou City:Chicago Method
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作者 Xie Dong Su Xiaoling +5 位作者 Liu Lei Liang Chunrong Liu Zhourong Li Yu Lan Qiu Ren Le 《Meteorological and Environmental Research》 CAS 2018年第4期24-29,共6页
The design rainstorm profile is the basis of scientifically and rationally planning and designing urban drainage system, which can provide scientific theoretical basis and accurate design parameters for municipal cons... The design rainstorm profile is the basis of scientifically and rationally planning and designing urban drainage system, which can provide scientific theoretical basis and accurate design parameters for municipal construction, water and planning departments. In this paper, the minute-minute rainfall process data at Liuzhou National Meteorological Observation Station from 1975 to 2014 were used. Chicago method was used to analyze and study design rainstorm profile in urban district of Liuzhou, and the profiles of the rainfalls lasting for 30 , 60 , 90, 120, 150, and 180 min were obtained. The results showed that the design rainstorm profile with the same duration in each reappearance period was consistent in Liuzhou, and short-time rainfall profile roughly showed single-peak shape. The peak of each short-time design rainstorm profile was almost in 1/3 part of the whole rainfall process, and the intensity of rainfall increased with the prolonging of the recurrence period. The rainfall intensity at the peak in the same reproducing period showed 11 decrease - increase -decrease" as the duration increased, and the peak value of rainfall lasting for 120 min was the maximum. 展开更多
关键词 Liuzhou City Design rainstorm profile Chicago method
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