Traffic flow model is improved by introducing variable brake distances with varying slopes.Stability of the traffic flow on a gradient is analyzed and the neutral stability condition is obtained.The KdV(Korteweg-de Vr...Traffic flow model is improved by introducing variable brake distances with varying slopes.Stability of the traffic flow on a gradient is analyzed and the neutral stability condition is obtained.The KdV(Korteweg-de Vries)equation is derived the use of nonlinear analysis and soliton solution is obtained in the meta-stable region.Solitary density waves are reproduced in the numerical simulations.It is found that as uniform headway is less than the safety distance solitary wave exhibits upward form,otherwise it exhibits downward form.In general the numerical results are in good agreement with the analytical results.展开更多
An extended compromise ratio method（CRM） based on fuzzy distances is developed to solve fuzzy multi-attribute group decision making problems in which weights of attributes and ratings of alternatives on attributes a...An extended compromise ratio method（CRM） based on fuzzy distances is developed to solve fuzzy multi-attribute group decision making problems in which weights of attributes and ratings of alternatives on attributes are expressed with values of linguistic variables parameterized using triangular fuzzy numbers.A compromise solution is determined by introducing the ranking index based on the concept that the chosen alternative should be as close as possible to the positive ideal solution and as far away from the negative ideal solution as possible simultaneously.This proposed method is compared with other existing methods to show its feasibility and effectiveness and illustrated with an example of the military route selection problem as one of the possible applications.展开更多
Seismic waveform clustering is a useful technique for lithologic identification and reservoir characterization.The current seismic waveform clustering algorithms are predominantly based on a fixed time window,which is...Seismic waveform clustering is a useful technique for lithologic identification and reservoir characterization.The current seismic waveform clustering algorithms are predominantly based on a fixed time window,which is applicable for layers of stable thickness.When a layer exhibits variable thickness in the seismic response,a fixed time window cannot provide comprehensive geologic information for the target interval.Therefore,we propose a novel approach for a waveform clustering workfl ow based on a variable time window to enable broader applications.The dynamic time warping(DTW)distance is fi rst introduced to effectively measure the similarities between seismic waveforms with various lengths.We develop a DTW distance-based clustering algorithm to extract centroids,and we then determine the class of all seismic traces according to the DTW distances from centroids.To greatly reduce the computational complexity in seismic data application,we propose a superpixel-based seismic data thinning approach.We further propose an integrated workfl ow that can be applied to practical seismic data by incorporating the DTW distance-based clustering and seismic data thinning algorithms.We evaluated the performance by applying the proposed workfl ow to synthetic seismograms and seismic survey data.Compared with the the traditional waveform clustering method,the synthetic seismogram results demonstrate the enhanced capability of the proposed workfl ow to detect boundaries of diff erent lithologies or lithologic associations with variable thickness.Results from a practical application show that the planar map of seismic waveform clustering obtained by the proposed workfl ow correlates well with the geological characteristics of wells in terms of reservoir thickness.展开更多
A method is proposed to deal with the uncertain multiple attribute group decision making problems,where 2-dimension uncertain linguistic variables(2DULVs)are used as the reliable way for the experts to express their f...A method is proposed to deal with the uncertain multiple attribute group decision making problems,where 2-dimension uncertain linguistic variables(2DULVs)are used as the reliable way for the experts to express their fuzzy subjective evaluation information.Firstly,in order to measure the 2DULVs more accurately,a new method is proposed to compare two 2DULVs,called a score function,while a new function is defined to measure the distance between two 2DULVs.Secondly,two optimization models are established to determine the weight of experts and attributes based on the new distance formula and a weighted average operator is used to determine the comprehensive evaluation value of each alternative.Then,a score function is used to determine the ranking of the alternatives.Finally,the effectiveness of the proposed method is proved by an illustrated example.展开更多
Future inter-satellite clock comparison on high orbit will require optical time and frequency transmission technology between moving objects.Here,we demonstrate robust optical frequency transmission under the conditio...Future inter-satellite clock comparison on high orbit will require optical time and frequency transmission technology between moving objects.Here,we demonstrate robust optical frequency transmission under the condition of variable link distance.This variable link is accomplished by the relative motion of a single telescope fixed on the experimental platform to a corner-cube reflector(CCR)installed on a sliding guide.Two acousto–optic modulators with different frequencies are used to separate forward signal from backward signal.With active phase noise suppression,when the CCR moves back and forth at a constant velocity of 20 cm/s and an acceleration of 20 cm/s^(2),we achieve the best frequency stability of 1.9×10^(-16) at 1 s and 7.9×10^(-19) at 1000 s indoors.This work paves the way for future studying optical frequency transfer between ultra-high-orbit satellites.展开更多
The present work aims to build a new statistical distance scale for planetary nebulae(PNe)based on a rigorous calibration sample.The distances of the calibration sample are derived from the trigonometric parallax meth...The present work aims to build a new statistical distance scale for planetary nebulae(PNe)based on a rigorous calibration sample.The distances of the calibration sample are derived from the trigonometric parallax method using the recent measurements of Gaia Early Data Release 3(Gaia EDR3).The new distance scale is created by applying the well-known linear relationship between the radio surface brightness temperature and the nebular radius.The calibration sample is made up of 96 PNe of accurately computed distances with uncertainties less than20%.Earlier ground-and space-based trigonometric parallaxes of PNe display inconsistency with those of Gaia,particularly the Hipparcos results.In addition,these measurements have appreciably lower precision than those of Gaia.When compared to the trigonometric technique,the expansion and kinematic methods exhibited more consistency than the spectroscopic,extinction,gravity,and photoionization methods.Furthermore,contrary to earlier results in the literature,the extinction and gravity methods,on average,underestimate and slightly overestimate the PN distances respectively.As a byproduct of extracting the Gaia parallaxes,we detect the radial velocity and variability for 14 and 3 PN central stars(CSs),respectively.To our knowledge,the variability of Hen 2-447 CS has been determined for the first time.展开更多
ihis paper examines the root causes of current cross-national institutional difference from the perspective of national hetereogeneity and provides detailed explanations on the justification and effectiveness of using...ihis paper examines the root causes of current cross-national institutional difference from the perspective of national hetereogeneity and provides detailed explanations on the justification and effectiveness of using cross-national genetic distance as the instrumental variable （IV） of institutional difference. We combined 10,585 samples by pairing 146 countries and regions, created a cross-national institutional distance variable composed of 14 indicators from the World Bank and the Heritage Foundation in three aspects including differences of political system, economic system and institutional implementation attributes, and conducted a cross-section IV estimation for the long-term effect of institutional differences on cross-national income gaps using data between 1996 and 2010. Empirical results indicate that institutional difference has a long-term significant positive effect on cross-national income gaps and such an effect has a tendency to increase during sample period. With factors like human capital, geographical factor, language and religion under control, we still arrived at similar conclusions. The empirical results are demonstrated to be robust using different genetic distance measurement indicators and estimation methods.展开更多
随着手机镜头成像距离范围的拓展,成像质量的测试范围也需要同步拓展。传统测试方法需频繁移动图卡,效率和精度受限。为了满足高精度调制传递函数(Modulation Transfer Function,MTF)测量的需求,设计并实现了一款可变模拟物距的平行光...随着手机镜头成像距离范围的拓展,成像质量的测试范围也需要同步拓展。传统测试方法需频繁移动图卡,效率和精度受限。为了满足高精度调制传递函数(Modulation Transfer Function,MTF)测量的需求,设计并实现了一款可变模拟物距的平行光管系统,可实现从150?mm至无穷远的物距模拟,具备16?mm的出瞳直径和75?mm的工作距离,适用于多数光学测试场景。使用ZEMAX对系统进行了多波长、多模拟物距条件下的优化,结果表明该光学系统在各项指标上均接近衍射极限。对系统的公差分析表明其具备良好的可加工性。镜头加工完成后,采用Trioptics公司的ImageMaster Universal进行MTF测试,并通过分辨率测试板对系统分辨率进行评估。实测结果表明,系统在各模拟物距下均能保持良好的成像质量,验证了该设计的工程应用价值。展开更多
Social distancing during COVID-19 has become one of the most important measures in reducing the risks of the spread of the virus. Implementing thesemeasures at universities is crucial and directly related to the physi...Social distancing during COVID-19 has become one of the most important measures in reducing the risks of the spread of the virus. Implementing thesemeasures at universities is crucial and directly related to the physical attendance ofthe populations of students, professors, employees, and other members on campus. This research proposes an automated scheduling approach that can help universities and schools comply with the social distancing regulations by providingassistance in avoiding huge assemblages of people. Furthermore, this paper proposes a novel course timetable-scheduling scheme based on four main constraints.First, a distance of two meters must be maintained between each student inside theclassroom. Second, no classrooms should contain more than 20% of their regularcapacity. Third, there would be no back-to-back classes. Lastly, no lectures shouldbe held simultaneously in adjacent classrooms. The proposed approach wasimplemented using a variable neighborhood search (VNS) approach with an adaptive neighborhood structure (AD-NS) to resolve the problem of scheduling coursetimetables at Al-Ahlyyia Amman University. However, the experimental resultsshow that the proposed techniques outperformed the standard VNS tested on university course timetabling benchmark dataset ITC2007-Track3. Meanwhile, theapproach was tested using datasets collected from the faculty of information technology at Al-Ahlyyia Amman University (Jordan). Where the results showed that,the proposed technique could help educational institutes to resume their regularoperations while complying with the social distancing guidelines.展开更多
Landslides significantly threaten lives and infrastructure, especially in seismically active regions. This study conducts a probabilistic analysis of seismic landslide runout behavior, leveraging a large-deformation f...Landslides significantly threaten lives and infrastructure, especially in seismically active regions. This study conducts a probabilistic analysis of seismic landslide runout behavior, leveraging a large-deformation finite-element (LDFE) model that accounts for the three-dimensional (3D) spatial variability and cross-correlation in soil strength — a reflection of natural soils' inherent properties. LDFE model results are validated by comparing them against previous studies, followed by an examination of the effects of univariable, uncorrelated bivariable, and cross-correlated bivariable random fields on landslide runout behavior. The study's findings reveal that integrating variability in both friction angle and cohesion within uncorrelated bivariable random fields markedly influences runout distances when compared with univariable random fields. Moreover, the cross-correlation of soil cohesion and friction angle dramatically affects runout behavior, with positive correlations enlarging and negative correlations reducing runout distances. Transitioning from two-dimensional (2D) to 3D analyses, a more realistic representation of sliding surface, landslide velocity, runout distance and final deposit morphology is achieved. The study highlights that 2D random analyses substantially underestimate the mean value and overestimate the variability of runout distance, underscoring the importance of 3D modeling in accurately predicting landslide behavior. Overall, this work emphasizes the essential role of understanding 3D cross-correlation in soil strength for landslide hazard assessment and mitigation strategies.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No. 61174175Postdoctoral Science Foundation of China under Grant No. 20100481265+1 种基金Special Foundation for Postdoctoral Innovation Program of Shandong Province under Grant No. 201102025the Scientific Project of Jinan City under Grant No. 201118006
文摘Traffic flow model is improved by introducing variable brake distances with varying slopes.Stability of the traffic flow on a gradient is analyzed and the neutral stability condition is obtained.The KdV(Korteweg-de Vries)equation is derived the use of nonlinear analysis and soliton solution is obtained in the meta-stable region.Solitary density waves are reproduced in the numerical simulations.It is found that as uniform headway is less than the safety distance solitary wave exhibits upward form,otherwise it exhibits downward form.In general the numerical results are in good agreement with the analytical results.
基金supported by the National Natural Science Foundation of China (7087111770571086)
文摘An extended compromise ratio method（CRM） based on fuzzy distances is developed to solve fuzzy multi-attribute group decision making problems in which weights of attributes and ratings of alternatives on attributes are expressed with values of linguistic variables parameterized using triangular fuzzy numbers.A compromise solution is determined by introducing the ranking index based on the concept that the chosen alternative should be as close as possible to the positive ideal solution and as far away from the negative ideal solution as possible simultaneously.This proposed method is compared with other existing methods to show its feasibility and effectiveness and illustrated with an example of the military route selection problem as one of the possible applications.
基金supported by the National Science and Technology Major Project (No. 2017ZX05001-003)。
文摘Seismic waveform clustering is a useful technique for lithologic identification and reservoir characterization.The current seismic waveform clustering algorithms are predominantly based on a fixed time window,which is applicable for layers of stable thickness.When a layer exhibits variable thickness in the seismic response,a fixed time window cannot provide comprehensive geologic information for the target interval.Therefore,we propose a novel approach for a waveform clustering workfl ow based on a variable time window to enable broader applications.The dynamic time warping(DTW)distance is fi rst introduced to effectively measure the similarities between seismic waveforms with various lengths.We develop a DTW distance-based clustering algorithm to extract centroids,and we then determine the class of all seismic traces according to the DTW distances from centroids.To greatly reduce the computational complexity in seismic data application,we propose a superpixel-based seismic data thinning approach.We further propose an integrated workfl ow that can be applied to practical seismic data by incorporating the DTW distance-based clustering and seismic data thinning algorithms.We evaluated the performance by applying the proposed workfl ow to synthetic seismograms and seismic survey data.Compared with the the traditional waveform clustering method,the synthetic seismogram results demonstrate the enhanced capability of the proposed workfl ow to detect boundaries of diff erent lithologies or lithologic associations with variable thickness.Results from a practical application show that the planar map of seismic waveform clustering obtained by the proposed workfl ow correlates well with the geological characteristics of wells in terms of reservoir thickness.
基金This work was supported by the Natural Science Foundation of Liaoning Province(2013020022).
文摘A method is proposed to deal with the uncertain multiple attribute group decision making problems,where 2-dimension uncertain linguistic variables(2DULVs)are used as the reliable way for the experts to express their fuzzy subjective evaluation information.Firstly,in order to measure the 2DULVs more accurately,a new method is proposed to compare two 2DULVs,called a score function,while a new function is defined to measure the distance between two 2DULVs.Secondly,two optimization models are established to determine the weight of experts and attributes based on the new distance formula and a weighted average operator is used to determine the comprehensive evaluation value of each alternative.Then,a score function is used to determine the ranking of the alternatives.Finally,the effectiveness of the proposed method is proved by an illustrated example.
基金Project supported by the National Key Research and Development Program of China(Grant No.2020YFB0408300)the National Natural Science Foundation of China(Grant No.62175246)+2 种基金the Natural Science Foundation of Shanghai,China(Grant No.22ZR1471100)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.YIPA2021244)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0300701).
文摘Future inter-satellite clock comparison on high orbit will require optical time and frequency transmission technology between moving objects.Here,we demonstrate robust optical frequency transmission under the condition of variable link distance.This variable link is accomplished by the relative motion of a single telescope fixed on the experimental platform to a corner-cube reflector(CCR)installed on a sliding guide.Two acousto–optic modulators with different frequencies are used to separate forward signal from backward signal.With active phase noise suppression,when the CCR moves back and forth at a constant velocity of 20 cm/s and an acceleration of 20 cm/s^(2),we achieve the best frequency stability of 1.9×10^(-16) at 1 s and 7.9×10^(-19) at 1000 s indoors.This work paves the way for future studying optical frequency transfer between ultra-high-orbit satellites.
文摘The present work aims to build a new statistical distance scale for planetary nebulae(PNe)based on a rigorous calibration sample.The distances of the calibration sample are derived from the trigonometric parallax method using the recent measurements of Gaia Early Data Release 3(Gaia EDR3).The new distance scale is created by applying the well-known linear relationship between the radio surface brightness temperature and the nebular radius.The calibration sample is made up of 96 PNe of accurately computed distances with uncertainties less than20%.Earlier ground-and space-based trigonometric parallaxes of PNe display inconsistency with those of Gaia,particularly the Hipparcos results.In addition,these measurements have appreciably lower precision than those of Gaia.When compared to the trigonometric technique,the expansion and kinematic methods exhibited more consistency than the spectroscopic,extinction,gravity,and photoionization methods.Furthermore,contrary to earlier results in the literature,the extinction and gravity methods,on average,underestimate and slightly overestimate the PN distances respectively.As a byproduct of extracting the Gaia parallaxes,we detect the radial velocity and variability for 14 and 3 PN central stars(CSs),respectively.To our knowledge,the variability of Hen 2-447 CS has been determined for the first time.
基金selected by the 12th China Annual Conference of Economicsthe process of drafting this paper,wereceived sponsorships from National Natural Science Foundation(Approval No.71003111)+4 种基金General Program of Cultural and Social Sciences for Higher Institutes of Learning in Guangdong Province(Approval No.10WYXM062)Special Fund of Basic Research Programs for Central Universities(Approval No.10wkjc05)Special Fund of Basic Research Programs for Central Universities(Approval No.10pywk11)Natural Science Foundation of Guangdong Province(Approval No.S2013010012456)"Theory of Guangdong"2013 crucial practical problems Foundation(Approval No.LLYJ1314)
文摘ihis paper examines the root causes of current cross-national institutional difference from the perspective of national hetereogeneity and provides detailed explanations on the justification and effectiveness of using cross-national genetic distance as the instrumental variable （IV） of institutional difference. We combined 10,585 samples by pairing 146 countries and regions, created a cross-national institutional distance variable composed of 14 indicators from the World Bank and the Heritage Foundation in three aspects including differences of political system, economic system and institutional implementation attributes, and conducted a cross-section IV estimation for the long-term effect of institutional differences on cross-national income gaps using data between 1996 and 2010. Empirical results indicate that institutional difference has a long-term significant positive effect on cross-national income gaps and such an effect has a tendency to increase during sample period. With factors like human capital, geographical factor, language and religion under control, we still arrived at similar conclusions. The empirical results are demonstrated to be robust using different genetic distance measurement indicators and estimation methods.
文摘随着手机镜头成像距离范围的拓展,成像质量的测试范围也需要同步拓展。传统测试方法需频繁移动图卡,效率和精度受限。为了满足高精度调制传递函数(Modulation Transfer Function,MTF)测量的需求,设计并实现了一款可变模拟物距的平行光管系统,可实现从150?mm至无穷远的物距模拟,具备16?mm的出瞳直径和75?mm的工作距离,适用于多数光学测试场景。使用ZEMAX对系统进行了多波长、多模拟物距条件下的优化,结果表明该光学系统在各项指标上均接近衍射极限。对系统的公差分析表明其具备良好的可加工性。镜头加工完成后,采用Trioptics公司的ImageMaster Universal进行MTF测试,并通过分辨率测试板对系统分辨率进行评估。实测结果表明,系统在各模拟物距下均能保持良好的成像质量,验证了该设计的工程应用价值。
文摘Social distancing during COVID-19 has become one of the most important measures in reducing the risks of the spread of the virus. Implementing thesemeasures at universities is crucial and directly related to the physical attendance ofthe populations of students, professors, employees, and other members on campus. This research proposes an automated scheduling approach that can help universities and schools comply with the social distancing regulations by providingassistance in avoiding huge assemblages of people. Furthermore, this paper proposes a novel course timetable-scheduling scheme based on four main constraints.First, a distance of two meters must be maintained between each student inside theclassroom. Second, no classrooms should contain more than 20% of their regularcapacity. Third, there would be no back-to-back classes. Lastly, no lectures shouldbe held simultaneously in adjacent classrooms. The proposed approach wasimplemented using a variable neighborhood search (VNS) approach with an adaptive neighborhood structure (AD-NS) to resolve the problem of scheduling coursetimetables at Al-Ahlyyia Amman University. However, the experimental resultsshow that the proposed techniques outperformed the standard VNS tested on university course timetabling benchmark dataset ITC2007-Track3. Meanwhile, theapproach was tested using datasets collected from the faculty of information technology at Al-Ahlyyia Amman University (Jordan). Where the results showed that,the proposed technique could help educational institutes to resume their regularoperations while complying with the social distancing guidelines.
基金supported by the National Natural Science Foundation of China(Grant No.U22A20596)the Shenzhen Science and Technology Program(Grant No.GJHZ20220913142605010)the Jinan Lead Researcher Project(Grant No.202333051).
文摘Landslides significantly threaten lives and infrastructure, especially in seismically active regions. This study conducts a probabilistic analysis of seismic landslide runout behavior, leveraging a large-deformation finite-element (LDFE) model that accounts for the three-dimensional (3D) spatial variability and cross-correlation in soil strength — a reflection of natural soils' inherent properties. LDFE model results are validated by comparing them against previous studies, followed by an examination of the effects of univariable, uncorrelated bivariable, and cross-correlated bivariable random fields on landslide runout behavior. The study's findings reveal that integrating variability in both friction angle and cohesion within uncorrelated bivariable random fields markedly influences runout distances when compared with univariable random fields. Moreover, the cross-correlation of soil cohesion and friction angle dramatically affects runout behavior, with positive correlations enlarging and negative correlations reducing runout distances. Transitioning from two-dimensional (2D) to 3D analyses, a more realistic representation of sliding surface, landslide velocity, runout distance and final deposit morphology is achieved. The study highlights that 2D random analyses substantially underestimate the mean value and overestimate the variability of runout distance, underscoring the importance of 3D modeling in accurately predicting landslide behavior. Overall, this work emphasizes the essential role of understanding 3D cross-correlation in soil strength for landslide hazard assessment and mitigation strategies.
