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Numerical modelling of resonance mechanisms in jointed rocks using transfer functions 认领 引用 被引量：1
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作者 Harry Holmes Chrysothemis Paraskevopoulou +2 位作者 Mark Hildyard Krishna Neaupane David P.Connolly 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第5期1076-1089,共14页
Resonance effects in parallel jointed rocks subject to stress waves are investigated using transfer functions,derived from signals generated through numerical modelling.Resonance is important for a range of engineerin... Resonance effects in parallel jointed rocks subject to stress waves are investigated using transfer functions,derived from signals generated through numerical modelling.Resonance is important for a range of engineering situations as it identifies the frequency of waves which will be favourably transmitted.Two different numerical methods are used for this study,adopting the finite difference method and the combined discrete element-finite difference method.The numerical models are validated by replicating results from previous studies.The two methods are found to behave similarly and show the same resonance effects;one operating at low frequency and the other operating at relatively high frequency.These resonance effects are interpreted in terms of simple physical systems and analytical equations are derived to predict the resonant frequencies of complex rock masses.Low frequency resonance is shown to be generated by a system synonymous with masses between springs,described as spring resonance,with an equal number of resonant frequencies as the number of blocks.High frequency resonance is generated through superposition of multiple reflected waves developing standing waves within intact blocks,described as superposition resonance.While resonance through superposition has previously been identified,resonance based on masses between springs has not been previously identified in jointed rocks.The findings of this study have implications for future analysis of multiple jointed rock masses,showing that a wave travelling through such materials can induce other modes of propagation of waves,i.e.spring resonance. 展开更多
关键词 Resonance Jointed rocks Finite difference method Discrete element Transfer functions Wave propagation
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The anomalous reactions of the geomagnetic horizontal field transfer functions before Tangshan earthquake 认领 引用 被引量：1
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作者 龚绍京 陈化然 +2 位作者 张翠芬 杨程君 马淑芹 《Acta Seismologica Sinica(English Edition)》 1997年第1期60-69,共10页
We have collected the data of variometers in period from 1972 through 1984 at Changli and Baijiatuan stations. The results calculated from 19 groups of data show: 1) There are no significant anomalies of A, B at Baiji... We have collected the data of variometers in period from 1972 through 1984 at Changli and Baijiatuan stations. The results calculated from 19 groups of data show: 1) There are no significant anomalies of A, B at Baijiatuan and that of B at Changli, but there are evident anomalous changes for A u, A v at Changli station. This result basically agrees to the a, b calculated using the method of measuring magnetograms, which demonstrates that the anomalies limited in the aftershock area and its neighbouring regions. 2) There are some changes of the inter station transfer functions of C u, C v, F u, F v before Tangshan earthquake, and the changes of the image parts C v, F v are more obvious, which is in agreement with the research results for Hualian earthquake. However, according to the results of Carlisle M =5.0 earthquake by Beamish(1982), the real parts F u, C u change more significantly. 展开更多
关键词 horizontal field inter station transfer functions underground electric structure abnormal field normal field
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Testing the transfer functions for the Geonor T-200B and Chinese standard precipitation gauge in the central Qinghai-Tibet Plateau 认领 引用 被引量：2
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作者 ZHANG Le-le GAO Li-ming +6 位作者 CHEN Ji ZHAO Lin CHEN Ke-long ZHAO Jing-yi LIU Guo-jun SONG Ting-xi LI Yan-kun 《Journal of Mountain Science》 SCIE CSCD 2022年第7期1974-1987,共14页
Accurately measuring precipitation is integral for understanding water cycle processes and assessing climate change in the Qinghai–Tibet Plateau(QTP).The Geonor T-200B weighing precipitation gauge with a single Alter... Accurately measuring precipitation is integral for understanding water cycle processes and assessing climate change in the Qinghai–Tibet Plateau(QTP).The Geonor T-200B weighing precipitation gauge with a single Alter shield(Geonor)and the Chinese standard precipitation gauge(CSPG)are widely used for measuring precipitation in the QTP.However,their measurements need to be adjusted for wetting loss,evaporation loss and windinduced undercatch.Four existing transfer functions for adjusting the Geonor-recorded and three transfer functions for adjusting the CSPG-recorded precipitation at hourly,daily or event scale has been proposed based on the precipitation intercomparison experiments conducted at a single site in different regions.Two latest transfer functions for the Geonor(which are referred to as K2017a and K2017b)at the half-hour time scale based on the precipitation intercomparison experiments at multiple stations in the northern hemisphere were provided in the World Meteorological Organization Solid Precipitation Intercomparison Experiment.However,the applicability of these transfer functions in the QTP has not been evaluated.Therefore,the current study carried out a precipitation measurement intercomparison experiment between August 2018 and September 2020 at a site in Beiluhe in central QTP.The performance of these transfer functions at this site was also evaluated on the basis of mean bias(MB),root mean squared error(RMSE)and relative total catch(RTC).The results are as follows:First,the unadjusted RTC values of the Geonor for rain,mixed(snow mixed with rain),snow and hail are 92.06%,85.35%,64.11%and 91.82%,respectively,and the unadjusted RTC values of the CSPG for the same precipitation types are 92.59%,81.32%,46.43%and 95.56%,respectively.Second,K2017a has the most accurate adjustment results for the Geonor-recorded snow and mixed precipitation at the half-hour time scale,and the post-adjustment RTC values increased to 98.25%and 98.23%,respectively.M2007e,an event-based transfer function,was found to have the most accurate adjustment results for the Geonorrecorded snow precipitation at the event scale,and the post-adjustment RTC value increased to 96.36%.Third,the existing transfer functions for CSPG underestimate snowfall,while overestimating rainfall.Fourth,hail is a significant precipitation type in central QTP.The catch efficiency of hail precipitation and the temperature when hail precipitation occurs are close to those of rain;moreover,the transfer functions for rain are suitable for hail as well. 展开更多
关键词 Precipitation observation errors Transfer function Geonor T-200B CSPG Qinghai-Tibet Plateau
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Great Guam earthquake(Msz=8.1)and time changes in geomagnetic transfer functions 认领 引用 被引量：1
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作者 陈伯舫 《Acta Seismologica Sinica(English Edition)》 1998年第2期122-125,共4页
GreatGuamearthquake（Msz＝8．1）andtimechangesingeomagnetictransferfunctionsPO－FANGCHEN（陈伯舫）DepartmentofPhysics，UniversityofHong...
关键词 geomagnetic transfer functions seismo-magnetic effect great Guam earthquake
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INTERPOLATION OF HEAD-RELATED TRANSFER FUNCTIONS USING SPHERICAL FOURIER EXPANSION 认领 引用 被引量：1
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作者 Huang Qinghua Fang Yong 《Journal of Electronics(China)》 2009年第4期571-576,共6页
A new interpolation algorithm for Head-Related Transfer Function （HRTF） is proposed to realize 3D sound reproduction via headphones in arbitrary spatial direction. HRTFs are modeled as a weighted sum of spherical ha... A new interpolation algorithm for Head-Related Transfer Function （HRTF） is proposed to realize 3D sound reproduction via headphones in arbitrary spatial direction. HRTFs are modeled as a weighted sum of spherical harmonics on a spherical surface. Truncated Singular Value Decomposition （SVD） is adopted to calculate the weights of the model. The truncation number is chosen according to Frobenius norm ratio and the partial condition number. Compared with other interpolated methods, our proposed approach not only is continuous but exploits global information of available directions. The HRTF from any desired direction can be and interpolated results demonstrate that our obtained more accurately and robustly. Reconstructed proposed algorithm acquired better performance. 展开更多
关键词 Head-Related Transfer Function （HRTF） Interpolation Spherical Fourier Expansion （SFE） Truncated Singular Value Decomposition （SVD） Partial condition number
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Experimental study on transfer functions of an active rotor under different flight conditions 认领 引用 被引量：5
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作者 Jinlong ZHOU Linghua DONG Weidong YANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2022年第8期107-120,共14页
Vibrations impose negative impacts on the effectiveness and public acceptance of helicopters.Active rotors with trailing-edge flaps have been proved to be an effective way to actively eliminate helicopter vibrations.F... Vibrations impose negative impacts on the effectiveness and public acceptance of helicopters.Active rotors with trailing-edge flaps have been proved to be an effective way to actively eliminate helicopter vibrations.For the existing control algorithm based on offline system identification,the transfer functions of an active rotor under different flight conditions are pre-requisites to implement closed-loop vibration control.In this study,a three-bladed active rotor with improved trailing-edge flaps is designed,and wind-tunnel tests are conducted to identify the transfer functions of this active rotor using frequency sweep and phase sweep methods.The experimental results demonstrate that these transfer functions are insensitive to the variation of flight speeds:the amplitude of the transfer function varies slightly,while the phase delay almost remains unchanged.In addition,this finding is validated through closed-loop vibration control tests with the active rotor.The transfer function obtained from the hover test results is also applicable to closed-loop vibration control tests under the forward flight conditions.This will dramatically simplify the implementation and operation of an active rotor. 展开更多
关键词 Active rotor Helicopter Trailing-edge flap Transfer function Vibration control Wind tunnel test
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Numerical modeling calculation for the spatial distribution characteristics of horizontal field transfer functions 认领 引用
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作者 龚绍京 陈化然 《Acta Seismologica Sinica(English Edition)》 2001年第6期676-684,共9页
Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer functions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part ... Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer functions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part has been given. The influences of source field period, the conductivity, the buried depth and the length of the conductor on the transfer functions were studied. The extrema of transfer functions appear at the center, the four corners and around the edges of conductor, and move with the edges. This feature demonstrates that around the edges are best places for transfer functions' observation. 展开更多
关键词 numerical modeling 3-D finite difference method horizontal field transfer function spatial distribution characteristics
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The preprocessing template for boundary element method simulation of head-related transfer functions 认领 引用
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作者 WANG Yewei YU Guangzheng 《Chinese Journal of Acoustics》 CSCD 2025年第4期637-655,共19页
The boundary element method,as a numerical approach based on integral equations,has been widely applied in the simulation of head-related transfer functions(HRTFs).However,its preprocessing still requires manual mesh ... The boundary element method,as a numerical approach based on integral equations,has been widely applied in the simulation of head-related transfer functions(HRTFs).However,its preprocessing still requires manual mesh construction,which not only consumes human effort but also compromises the reproducibility of the simulation results.In this study,a representative head mesh template was selected based on morphological correlations of human head shapes,enabling a series of automated preprocessing steps including coordinate alignment,mesh refinement,and source placement at the ear canal entrance,to simplify the computational model and enhance both model processing and HRTF calculation efficiency.Results obtained from the template-based preprocessing demonstrate that,compared with manual processing,the model mesh exhibits a consistent vertex sequence,with rotational and translational errors of the model coordinate system within approximately 3°and 3 mm,respectively,and discrepancies in ear canal source positions not exceeding 2.5 mm.The entire modeling procedure is fully automated by computer,and its time consumption is negligible compared with manual processing.Further analysis indicates that the template-based computational model reduces the calculation time of full-sphere HRTFs by approximately 55%,while maintaining spectral errors within 1.0 dB below 16 kHz,and interaural time difference deviations confined to the lateral directions and less than 10μs.Finally,validation with a virtual auditory localization model confirmed that no significant differences exist in the localization outcomes of HRTF derived from the two modeling methods.These findings demonstrate that the proposed modeling approach significantly improves the efficiency of HRTF numerical computation without sacrificing accuracy,while optimizing and standardizing the preprocessing workflow of computational models,making it suitable for large-scale personalized HRTF simulations. 展开更多
关键词 Head-related transfer functions Boundary element method Calculation model Mesh template
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Force-driven ionic transfer in dual-charge MXene membranes for self-powered linear pressure sensing 认领 引用
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作者 Yuhan Tang Xingyao Dai +3 位作者 Junjie Zou Yang Yue Yanan Ma Xin Zhang 《Journal of Materiomics》 SCIE EI CSCD 2026年第3期117-126,共10页
Traditional pressure sensors often lack the required linear characteristics in their force-electric transfer functions,which limits the practicality in numerous fields such as the Internet of Things(IoT)and artificial... Traditional pressure sensors often lack the required linear characteristics in their force-electric transfer functions,which limits the practicality in numerous fields such as the Internet of Things(IoT)and artificial intelligence.This study has developed a self-powered pressure sensor based on Ti3C2Tx-MXene membranes,which are modified with cellulose nanofibrils(CNF)and poly diallyl dimethyl ammonium chloride(PDDA)to create composite membranes with negative and positive charges.Owing to their two-dimensional nanofluidic channels and surface charge properties,these composite membranes can efficiently convert mechanical pressure into electrical signals.Notably,the output signals exhibit a linear relationship with applied pressure,significantly simplifying signal processing.To optimize the sensing performance,the nanofluidic channel structures of the composite membranes were fine-tuned to enhance the sensitivity and response speed.Furthermore,the influence of electrolyte concentrations on sensing performance,including detection range,sensitivity,and stability,was systematically investigated.Experimental results demonstrate that the sensor exhibits excellent linear response,high sensitivity,fast responseecovery times,good stability,and repeatability.This research not only provides new ideas for the design of self-powered sensors but also advances the application of 2D materials in the field of intelligent sensing. 展开更多
关键词 Self-powered pressure sensor MXene Nanofluid Ion transport Linear transfer function
Design and validation on a multiple sound source fast-measurement system of near-field head-related transfer functions 认领 引用 被引量：1
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作者 YU Guangzheng LIU Yu XIE Bosun 《Chinese Journal of Acoustics》 CSCD 2018年第2期219-240,共22页
Near-field head-related transfer functions （HRTFs） are essential to scientific re- searches of binaural hearing and practical applications of virtual auditory display. High ef- ficiency, accuracy and repeatability a... Near-field head-related transfer functions （HRTFs） are essential to scientific re- searches of binaural hearing and practical applications of virtual auditory display. High ef- ficiency, accuracy and repeatability are required in a near-field HRTF measurement. Hence, there is no reference which intents on solving the measuring difficulties of near-field HRTF for human subjects. In present work, an efficient near-field HRTF measurement system based on computer control is designed and implemented, and a fast calibration method for the system is proposed to first solve the measurement of near-field HRTF for human subjects. The efficiency of measurement is enhanced by a comprehensive design on the acoustic, electronic and mechanical parts of the system. And the accuracy and repeatability of the measurement are greatly im- proved by carefully calibrating the positions of sound source, subject and binaural microphones. This system is suitable for near-field HRTF measurement at various source distances within 1.0 m, for both human subject and artificial head. The time costs of HRTF measurement at a single sound source distance and full directions has been reduced to less than 20 minutes. The measurement results indicate that the accuracy of the system satisfies the actual requirements. The system is applicable to scientific research and can be used to establish an individualized near-field HRTF database for human subjects. 展开更多
关键词 Design and validation on a multiple sound source fast-measurement system of near-field head-related transfer functions
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Effect of Multiple Models of Closed-loop Transfer Functions on Inter-harmonic Oscillation Characteristics of Grid-connected PMSG 认领 引用 被引量：6
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作者 Jingyi Li Jianjun Yang +3 位作者 Xiaorong Xie Haozhi Li Ke Wang Zhaohui Shi 《CSEE Journal of Power and Energy Systems》 SCIE EI CSCD 2024年第5期1955-1964,共10页
Establishing a suitable closed-loop transfer function model for the grid-connected PMSG system is the key basis in performing inter-harmonic characteristics analysis.Multiple closed-loop transfer functions can be cons... Establishing a suitable closed-loop transfer function model for the grid-connected PMSG system is the key basis in performing inter-harmonic characteristics analysis.Multiple closed-loop transfer functions can be constructed when different components of the converter controller are taken into account.However,the effect of different components of the converter controller on inter-harmonic stability analysis is not clear.In this paper,the complete transfer function,considering different loops,is first given.Based on the complete closed-loop transfer function,the DC-link,PLL and voltage forward-feed are removed step by step to derive different closed-loop transfer functions.The inter-harmonic related poles of different closed-loop transfer functions are further calculated to analyze the effect of closedloop transfer functions on inter-harmonic characteristics analysis.Finally,by performing time domain simulation,the correctness of the theoretical analysis results is verified.The results show that under the conditions of a weak AC system,each loop of the converter control system will reduce the stability of the interharmonic in the sub-synchronous frequency range and influence the inter-harmonic oscillation frequency.The transfer function needs to consider the influence of each loop to accurately calculate the inter-harmonic stability of the system. 展开更多
关键词 Closed-loop transfer function converter controller inter-harmonic characteristics PMSG
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A quantitative reconstruction of the paleoenviornmental variations of the South Yellow Sea inner shelf based on benthic foraminiferal transfer functions 认领 引用 被引量：2
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作者 SUN RongTao LI TieGang +2 位作者 CHANG FengMing NAN QingYun LIU Xiao 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第9期1633-1642,共10页
Transfer functions between the benthic foraminiferal fauna of seventy-one sediment surface-samples retrieved from the South Yellow Sea inner shelf and the environmental factors, including the summer bottom-water salin... Transfer functions between the benthic foraminiferal fauna of seventy-one sediment surface-samples retrieved from the South Yellow Sea inner shelf and the environmental factors, including the summer bottom-water salinity(Ss), the summer bottom-water temperature(Ts) and the winter bottom-water temperature(Tw) have been developed utilizing weighted averaging partial least square regression(WA-PLS). Subsequently, the transfer functions have been applied to a late Holocene piston core SY01 from the South Yellow Sea inner shelf, established the variation curves of the Ss, Ts, and Tw during the last 3.9 cal. ka. The Ss and Ts showed a nearly synchronous trend to the published stalagmite δ18O curve from the Jiuxian Cave, meaning they could be used as reliable indicators for the summer monsoon. Similarly, the Tw could be used as an indicator for the winter monsoon for its synchronous change to the insensitive grain size variation of the core ZY-2 retrieved from the Central Yellow Sea mud area. These results suggest that transfer functions based on benthic foraminiferal fauna can be a potentially useful tool in palaeoceanographic and palaeoenvironmental research along the Chinese seaboard. 展开更多
关键词 South Yellow Sea benthic foraminifera transfer function paleoclimate reconstruction East Asian monsoon
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Heterogeneous transfer functions multi-layer perceptron (MLP) for meteorological time series forecasting 认领 引用 被引量：1
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作者 C.Voyant M.L.Nivet +2 位作者 CPaoli M.Muselli G.Notton 《International Journal of Modeling, Simulation, and Scientific Computing》 EI 2015年第2期49-55,共7页
In this paper,we propose to study four meteorological and seasonal time series(TS)coupled with a multi-layer perceptron(MLP)modeling.We chose to combine two transfer functions for the nodes of the hidden layer,and to ... In this paper,we propose to study four meteorological and seasonal time series(TS)coupled with a multi-layer perceptron(MLP)modeling.We chose to combine two transfer functions for the nodes of the hidden layer,and to use a temporal indicator(time index as input)in order to take into account the seasonal aspect of the studied TS.The results of the prediction concern two years of measurements and the learning step,eight independent years.We show that this methodology can improve the accuracy of meteorological data estimation compared to a classical MLP modeling with a homogenous transfer function. 展开更多
关键词 Artificial neural network meteorology time series transfer function
Tunable multi-wavelength microwave photonic filter based on the superposition of transfer functions 认领 引用
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作者 俞杨 郑小平 +1 位作者 张汉一 周炳砚 《Chinese Optics Letters》 SCIE EI CAS CSCD 2013年第12期9-12,共4页
A microwave photonic filter （MPF） with reconfigurability and tunability resulting from the superposition of the transfer functions is proposed. Based on the Vernier effect between the optical frequency combs and the... A microwave photonic filter （MPF） with reconfigurability and tunability resulting from the superposition of the transfer functions is proposed. Based on the Vernier effect between the optical frequency combs and the periodic optical filters, each comb line can be mapped into a sub-filter in the electronic field. The sub-filters are superposed to obtain the total transfer function of the MPF. By manipulating a few comb lines, we can reconfigure the passband shape, tune the bandwidth, and adjust the center frequency independently. Experiments verify that the bandwidth can be tuned from 224.8 to 674.3 MHz, and that the center frequency ranges from 1 to 4 CHz. 展开更多
关键词 Bandpass filters Bandwidth Transfer functions
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Application and measurement of underwater acoustic reciprocity transfer functions in reverberant sound field 认领 引用
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作者 CHENG Guo XU Rongwu +1 位作者 HE Lin SUN Hongling 《Chinese Journal of Acoustics》 2014年第4期369-378,共10页
The reciprocity measurement theory in anomalous reverberant sound fields was investigated.An improved method Was proposed due to the interrelated errors.The source volume velocity Was corrected by spatial average of m... The reciprocity measurement theory in anomalous reverberant sound fields was investigated.An improved method Was proposed due to the interrelated errors.The source volume velocity Was corrected by spatial average of measurement results and evaluation of the reverberant sound field influence on acoustic energy density.The result was validated in underwater experiment,corrected reciprocity measurement results were almost the same as direct measurement results.It indicates that reverberant sound field does not affect the validitv of the principle,but influences the obtainment of source volume velocity,then influences the measurement of transfer functions with the principle.The proposed method is simple and effective in anomalous reverberant sound fields.The study mav be valuable for the applications which are based on the principle. 展开更多
关键词 Application and measurement of underwater acoustic reciprocity transfer functions in reverberant sound field
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Phase behaviors of transfer functions in Vibrating systems 认领 引用 被引量：1
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作者 ZHU JianyuanOHLRICH Mogens 《Chinese Journal of Acoustics》 1998年第3期244-253,共10页
This paper investigates the applicabilitles of pole-zero model and wave propagation theory in estimating the phase characteristics of vibrating systems. The measured phase spectra are compared with the estlmated rever... This paper investigates the applicabilitles of pole-zero model and wave propagation theory in estimating the phase characteristics of vibrating systems. The measured phase spectra are compared with the estlmated reverberant phase limit and wave propagation phase. The relations between transfer function phase and frequency, damping, and separation distance are described. The present results show that the pole-zero model provides a reasonable estimation of the reverberant phase limit in low frequency band below an identified transition frequency.The reverberant phase is linearly dependent on frequency in this band, but from the transition frequency and onwards the phase increases only with the square root of frequency. This behavior is characteristic for free propagating waves 展开更多
关键词 Phase behaviors of transfer functions in Vibrating systems
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Vibration Transfer Function of Railway Vehicle System and its Spatial Coherence Under Vertical Track Irregularity Conditions 认领 引用
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作者 Peng Lu Xi Wang Yu Hou 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2025年第2期374-393,共20页
Current research on rail vehicle system vibrations primarily relies on numerical methods,with vibration transfer functions commonly derived through data fitting.However,the physical mechanisms underlying these vibrati... Current research on rail vehicle system vibrations primarily relies on numerical methods,with vibration transfer functions commonly derived through data fitting.However,the physical mechanisms underlying these vibrations are not well understood.To clarify the vibration transfer function and its characteristics,four basic input vectors are defined,and an analytical method is proposed.The vibration transfer functions of the vehicle system are solved,and their spatial coherence is analyzed.The results show that there are two spatial scales and four coherent modes in the vehicle system.The track irregularity wavelengths are combined with two spatial scales to alter the proportions of basic input vectors and then show the characteristics of spatial coherence.Four coherent modes are involved in wheel-rail force and primary suspension force;two coherent modes are involved in bogie vertical motion;and their dominant modes vary with the input frequency.On the other hand,the coherent modes involved in the bogie pitching motion and vehicle body motion are single and fixed over the whole range of frequency.This study presents an analytical method for the rapid solution of dynamic responses in vehicle systems and systematically analyzes the coherence behavior of vibration transfer functions with respect to tracking irregularity wavelengths. 展开更多
关键词 Vertical track irregularity Vibration transfer function Spatial coherence Dominant mode Transfer matrix method
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Analysis of the optical quality by determining the modulation transfer function for anterior corneal surface in myopes 认领 引用 被引量：6
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作者 Yan-Zhen Zheng Yan-Peng Chen +2 位作者 Yan Qiu Guo-Guang Zhai Yao-Yu Li 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2012年第2期196-201,共6页
AIM:To describe the characteristics of modulation transfer function(MTF)of anterior corneal surface,and obtain the the normal reference range of MTF at different spatial frequencies and optical zones of the anterior c... AIM:To describe the characteristics of modulation transfer function(MTF)of anterior corneal surface,and obtain the the normal reference range of MTF at different spatial frequencies and optical zones of the anterior corneal surface in myopes.METHODS:Four hundred eyes from 200 patients were examined under SIRIUS corneal topography system.Phoenis analysis software was applied to simulate the MTF curves of anterior corneal surface at vertical and horizontal meridians at the 3,4,5,6,7mm optical zones of cornea.The MTF values at spatial frequencies of 5,10,15,20,25,30,35,40,45,50,55 and 60 cycles/degree(c/d)were selected.RESULTS:The MTF curve of anterior corneal surface decreased rapidly from low to intermediate frequency(0-15cpd)at various optical zones of cornea,the value decreased to 0 slowly at higher frequency(>15cpd).With the increase of the optical zones of cornea,MTF curve decreased gradually.3)In the range of 3 mm-6 mm optical zones of the cornea,the MTF values measured at horizontal meridian were greater than the corresponding values at horizontal meridian of each spatial frequency,the difference was statistically significant(P<0.05).At 7 mm optical zones of cornea,the MTF values measured at horizontal meridian were less than the corresponding values at vertical meridian at 10-60 spatial frequencies(cpd),and the difference was statistically significant in 25,30,35,40,45,50 cpd(P<0.05).CONCLUSION:MTF can be used to describe the imaging quality of optical systems at anterior corneal surface objectively in detail. 展开更多
关键词 modulation transfer function optical quality cornea point spread function optical transfer function phase transfer function
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A hardening load transfer function for rock bolts and its calibration using distributed fiber optic sensing 认领 引用 被引量：9
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作者 Assaf Klar Ori Nissim Itai Elkayam 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第11期2816-2830,共15页
Confinement of rock bolts by the surrounding rock formation has long been recognized as a positive contributor to the pull-out behavior,yet only a few experimental works and analytical models have been reported,most o... Confinement of rock bolts by the surrounding rock formation has long been recognized as a positive contributor to the pull-out behavior,yet only a few experimental works and analytical models have been reported,most of which are based on the global rock bolt response evaluated in pull-out tests.This paper presents a laboratory experimental setup aiming to capture the rock formation effect,while using distributed fiber optic sensing to quantify the effect of the confinement and the reinforcement pull-out behavior on a more local level.It is shown that the behavior along the sample itself varies,with certain points exhibiting stress drops with crack formation.Some edge effects related to the kinematic freedom of the grout to dilate are also observed.Regardless,it was found that the mid-level response is quite similar to the average response along the sample.The ability to characterize the variation of the response along the sample is one of the many advantages high-resolution fiber optic sensing allows in such investigations.The paper also offers a plasticity-based hardening load transfer function,representing a"slice"of the anchor.The paper describes in detail the development of the model and the calibration/determination of its parameters.The suggested model captures well the coupled behavior in which the pull-out process leads to an increase in the confining stress due to dilative behavior. 展开更多
关键词 Rock bolts Distributed fiber optic sensing Pull-out tests Load transfer function Hardening model
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Optical Transfer Function Reconstruction in Incoherent Fourier Ptychography 认领 引用 被引量：3
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作者 谢宗良 亓波 +5 位作者 马浩统 任戈 谭玉凤 贺璧 曾恒亮 江川 《Chinese Physics Letters》 SCIE EI CAS CSCD 2016年第4期48-51,共4页
An optical transfer function （OTF） reconstruction model is first embedded into incoherent Fourier ptychography （IFP）. The leading result is a proposed algorithm that can recover both the super-resolution image and... An optical transfer function （OTF） reconstruction model is first embedded into incoherent Fourier ptychography （IFP）. The leading result is a proposed algorithm that can recover both the super-resolution image and the OTF of an imaging system with unknown aberrations simultaneously. This model overcomes the difficult problem of OTF estimation that the previous IFP faces. The effectiveness of this algorithm is demonstrated by numerical simulations, and the superior reconstruction is presented. We believe that the reported algorithm can extend the original IFP for more complex conditions and may provide a solution by using structured light for characterization of optical systems＇ aberrations. 展开更多
关键词 OTF IFP Optical Transfer Function Reconstruction in Incoherent Fourier Ptychography of in
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