AIM:To investigate the effect of using base-out prisms on nystagmus,visual acuity and contrast sensitivity in patients with albinism.METHODS:In this interventional study,patients with albinism who had nystagmus were e...AIM:To investigate the effect of using base-out prisms on nystagmus,visual acuity and contrast sensitivity in patients with albinism.METHODS:In this interventional study,patients with albinism who had nystagmus were enrolled.A comprehensive eye exam was conducted,which included refraction,assessment of far and near vision acuity,and contrast sensitivity measurements.To check for the nystagmus,a videonystagmography was used.The tests were carried out in three modes:without any correction,with optical correction,and with correction using base-out prisms in three different powers,including 4,6,and 8 prism diopters.RESULTS:Totally 23 patients with average age of 28.65±12.13 were examined.It was found that the use of optical correction and optical correction with prisms resulted in a statistically significant improvement in both far(at least:P<0.006)and near visual acuity(at least:P<0.001 except for prism 8;P<0.02).In addition,contrast sensitivity significantly improved at all low and medium frequencies except for correction with prism 8 in frequency 1.5(at least:P<0.01 except for prism 4,frequency 6;P=0.04).no significant improvement was observed in the evaluation of nystagmus characteristics.CONCLUSION:Optical correction with a prism can improve visual acuity and some spatial frequencies,but failed to improve nystagmus parameters.展开更多
The achievements made in China in the field of the theory of conjugation for reflecting prisms are outlined which mainly includes 6 theorems, 2 corollaries, over 30 formulae, 4 matric operators, 20 characteristic para...The achievements made in China in the field of the theory of conjugation for reflecting prisms are outlined which mainly includes 6 theorems, 2 corollaries, over 30 formulae, 4 matric operators, 20 characteristic parameters, a new principle for dassification, and a new system of graphical tabulation for reflecting prisms. As an approach to developing the theory, an imaginary physical model called 'rigid body's kinematics model' has been creatively initiated to simulate the real physical phenomena of both image formation and image motion for reflecting prisms. Such a method of treatment has been successfully making the evolving theory more complete, more systematic, more generalized, and unique as well.展开更多
·AIM: To evaluate the efficacy of a new modality for improving visual acuity (VA) in pediatric patients with anisometropic amblyopia. · METHODS: Retrospective and interventional case series. Medical records ...·AIM: To evaluate the efficacy of a new modality for improving visual acuity (VA) in pediatric patients with anisometropic amblyopia. · METHODS: Retrospective and interventional case series. Medical records of 360 children with anisometropic amblyopia treated with a modality that included rotated prisms, lenses, and near activities from January 2008 to January 2012 were analyzed. Characteristics such as improvement of VA and contrast sensitivity in amblyopic eyes and resolution of amblyopia (VA ≤ 0.1logMAR or a difference of ≤ 2 lines in logMAR between the eyes) were assessed. ·RESULTS: Among the patients, the mean VA of the amblyopic eyes improved from 0.48logMAR (SD=0.16) to 0.12logMAR (SD =0.16) and the mean VA improvement was 0.36logMAR (SD =0.10, P【0.001). Resolution of amblyopia was achieved in 233 of 360 patients (64.72%). The mean time for resolution of amblyopia was 8.05 weeks (SD=4.83) or 14.14 sessions (SD=8.76). Among the study group, refraction error did not change significantly after treatment (P=0.437). We found that better baseline VA may be related to success and shorten the time to amblyopic resolution. ·CONCLUSION: VA and contrast sensitivity improved with rotated prisms, correcting lenses, and near activities in children with anisometropic amblyopia. The VA improvement by this modality was comparable to other methods. However, the time to resolution of amblyopia was shorter with this method than with other modalities. Rotated prisms combined with near acuity could provide an alternative treatment in children with anisometropic amblyopia who can’t tolerant traditional therapy method like patching.展开更多
We systematically investigate the power distribution characteristics of microjets generated by prismatic scatterers with different shapes at sub-THz region(λ = 8.57 mm). Among these prismatic scatterers, the hexagona...We systematically investigate the power distribution characteristics of microjets generated by prismatic scatterers with different shapes at sub-THz region(λ = 8.57 mm). Among these prismatic scatterers, the hexagonal-type one shows better focusing feature than the others. Aiming at the hexagonal-type one, we propose a double-layer scatterer composed of a Teflon hexagonal prism as an outer layer and a semiconductor cuboid as an inner layer. Aiming at the double-layer scatterer, we further study the effects of refractive index, size, and shape of the inner cuboid on microjet’s features. The study allows us to present an optimized double-layer scatterer, which has a side length λ/2(λ) and a refractive index 2.0(1.4) for the inner(outer) layer. We show that the optimized scatterer can produce an ultra-strong, ultra-narrow microjet with a power enhancement of;0 and a full width at half maximum(FWHM) of;0.26λ, and the microjet is just located at the output face. The microjet keeps compact within the distance range of λ from the output face. These features and effects are explained from the viewpoint of ray optics theory. According to the optimized double-layer scatterer, we further study the multi-frequency focusing features of the microjets, and find that the microjet remains good features at harmonic frequencies 2f_(0) and 3f_(0). In addition, we investigate the effect of an Au sphere presence in the center of the microjet on the power distribution. The results show that a spherical dark spot with a size similar to that of the Au sphere emerges in the area where the Au sphere is placed. The feature can be used to measure the size of a metallic particle.展开更多
Hands-on Mini Lab Work with a partner.·Use the cubes to build a rectangular prism with a length of 8 centimeters.·Count the number of squares on each face.The sum is the surface area.1.Record the dimensions,...Hands-on Mini Lab Work with a partner.·Use the cubes to build a rectangular prism with a length of 8 centimeters.·Count the number of squares on each face.The sum is the surface area.1.Record the dimensions,volume,and surface area in a table.2.Build two more prisms using all of the cubes.For each,record the dimensions,volume,and surface area.3.Describe the rectangular prisms with the greatest and least surface areas.展开更多
The influence of the refractive index n2 of optical cement on the structure angle, field angle, and transmission of Glan-Thompson prism has been studied in detail. The results show that the structure angle will increa...The influence of the refractive index n2 of optical cement on the structure angle, field angle, and transmission of Glan-Thompson prism has been studied in detail. The results show that the structure angle will increase with the decrease of n2 under the condition of the largest field angle. Thus, the ratio of length to width （L/A） of the prism will decrease, which means more materials can be saved. When the value of L/A is 3.0 or 2.5 in the routine design, the field angle will firstly increase and then decrease with the increment of n2. Two routine designs with the n2 values of 1.47 and 1.45 have the optimal field angle. In addition, n2 also has great influence on light intensity transmittance of the prism. Considering all these factors, it will be the best choice with L/A = 2.5 and n2 = 1.45 - 1.46.展开更多
The dispersion of a pair of prisms is analyzed by means of a ray-tracing method operating at other than tip-to-tip propagation of the prisms, taking into consideration the limited spectral bandwidth. The variations of...The dispersion of a pair of prisms is analyzed by means of a ray-tracing method operating at other than tip-to-tip propagation of the prisms, taking into consideration the limited spectral bandwidth. The variations of the group delay dispersion and the third-order dispersion for a pair of prisms are calculated with respect to the incident position and the separation between the prisms. The pair of prisms can provide a wide range of independent and continuous third-order dispersion compensation. The effect of residual third-order dispersion on the pulse contrast ratio and pulse duration is also calculated. The residual third-order dispersion not only worsens the pulse contrast ratio, but also increases the pulse duration to the hundreds of femtosecond range for a tens of femtosecond pulse, even when the residual thirdorder dispersion is small. These phenomena are helpful in compensating for the residual high-order dispersion and in understanding its effect on pulse contrast ratios and pulse durations in ultrashort laser systems.展开更多
Evaluation of damage evolution effects in biodegradable pure Mg was carried out,using transmission electron microscope as surrogate irradiation for high-energy radionuclide β decay in Brachytherapy.Time-dependent qua...Evaluation of damage evolution effects in biodegradable pure Mg was carried out,using transmission electron microscope as surrogate irradiation for high-energy radionuclide β decay in Brachytherapy.Time-dependent quantitative defect production,evolution dynamics,and evolution statistics were revealed in-situ for two prism foils(z=[1.210],[10.10]),in as-received and heat-treated pure Mg,after 300 keV electron irradiation up to 0.468 dpa at R.T.Preferred nucleation of basal-plane interstitial-type 1/6<20.23>loops was confirmed,in addition to a small portion of prism-plane 1/3<11.20>loops.No cavities were found.A higher yield of point defect concentration and a more evident trend of defect coarsening were identified in[1.210]than in[10.10].Pre-existing dislocations(on the orders of 10^(13)−10^(14) m^(−2))in pure Mg resulted in a delay of the first occurrence of visible defects.Defect migration and elastic interactions governed the microstructural evolution of electron irradiation damage in pure Mg,giving rise to events of loop coalescence,growth,and sometimes rotation of habit plane.The influence of incident electron energy can be correlated to the rates of point defect production,and is quantifiable;however,interfered by defect cluster stability,defect mobility,and defect interactions.This forms an important theoretical basis for the application of Mg subjected to MeV-level β-decay radiation in Brachytherapy.The paper concludes with a brief comparison between Mg and conventional Ti casing,outlines the advantages and challenges,and provides reference points for the validation of Mg/Mg-alloys in Brachytherapy seed application.展开更多
Arc-continent collision zones are critical areas where uplift,accretion,and erosion processes significantly influence the growth,elimination,or recycling of the continental crust.The Zagros–Makran Transition Zone,loc...Arc-continent collision zones are critical areas where uplift,accretion,and erosion processes significantly influence the growth,elimination,or recycling of the continental crust.The Zagros–Makran Transition Zone,located along the Minab-Zendan Fault,represents a convergence boundary between the Zagros continental domain and the Makran accretionary prism in southern Iran from the Cretaceous onwards.Several tectonic slices,including Neotethys ophiolitic remnants and the Ganj and Bajgan-Durkan complexes,have accreted along the southern margin of the Eurasian Plate during subduction in the western Makran wedge.To clarify the growth steps of the Makran Prism and the internal deformation associated with arc-continent collision,we used a provenance study of sandstones from the western Makran accretionary prism involving petrography of the main detrital components and U–Pb dating,Hf isotopic values,and trace elements of detrital zircon grains.Our findings reveal a progressive scenario in which oceanic arc-related rocks of the∼99 Ma Ganj Complex with Hf values ranging from+10 to+16 were uplifted during the Early to Late Eocene.The Eocene fore-arc sediments were sourced from the∼49–47 Ma Urumieh-Dokhtar Magmatic Arc with Hf values between−5 and+12,as well as from the Ganj Complex.The Jurassic–Cretaceous Bajgan-Durkan Complex was uplifted due to the Late Eocene to Oligocene collision of various terranes along the southern margin of the Eurasian Plate.This led to a major sediment influx into the Makran trench with a detrital signal in the range∼175–160 Ma with Hf isotopic values from−3 to+4 and alongside the Urumieh-Dokhtar Magmatic Arc with detrital ages ranging∼46–37 Ma and ca.80 Ma.Notably,metamorphic lithic grains began to appear in the sediments in the Late Eocene.The initial arrival of sediments from the Arabian margin to the arc-continent suture zone along the Minab-Zendan Fault indicates the onset of initial collision.During the Late Oligocene–Early Miocene,detrital zircon ages in the range of∼610–520 Ma,sourced from the Arabian basement,were deposited in the trench basin together with components from the Eocene Urumieh-Dokhtar Magmatic Arc and Cretaceous ophiolitic clasts of∼93 Ma with Hf isotopic values of+12 to+16.Following the development and uplift of the orogen from the Middle Miocene onward,detrital zircon grains from the Cretaceous–Miocene Urumieh-Dokhtar Magmatic Arc,Jurassic–Cretaceous Bajgan-Durkan Complex,and Cretaceous ophiolites are present in both the Makran and Zagros sedimentary domains.展开更多
Space-time prism(STP)is a fundamental concept in time geography and has been predominately constructed in unimodal transportation networks.Due to the vast trip chaining options by private vehicles and public transport...Space-time prism(STP)is a fundamental concept in time geography and has been predominately constructed in unimodal transportation networks.Due to the vast trip chaining options by private vehicles and public transportation,it was challenging to construct STP over multimodal transportation networks.We previously put forward an efficient method to narrow down the action space for trip chaining and construct STPs effectively in a multimodal supernetwork.This study applies multimodal STP modeling to measure space-time accessibility and equality of daily activity opportunities.Two equality measures(Gini coefficient and 20:20 ratio)are derived from two space-time accessibility measures based on delineated STPs.We examine the equality of access to shopping and leisure opportunities in the Rotterdam-The Hague metropolitan area,the Netherlands.The results show the effects of various factors on accessibility and equality.It is found that although the study area has relatively low inequality using single modes,multimodal trip chaining further reduces inequality to access the distributed space-time opportunities.展开更多
The prediction of bathymetry has advanced significantly with the development of satellite altimetry.However,the majority of its data originate from marine gravity anomaly.In this study,based on the expression of verti...The prediction of bathymetry has advanced significantly with the development of satellite altimetry.However,the majority of its data originate from marine gravity anomaly.In this study,based on the expression of vertical gravity gradient(VGG)of a rectangular prism,the governing equations for determining sea depths to invert bathymetry.The governing equation is solved by linearization through an iterative process,and numerical simulations verify its algorithm and its stability.We also study the processing methods of different interference errors.The regularization method improves the stability of the inversion process for errors.A piecewise bilinear interpolation function roughly replaces the low-frequency error,and numerical simulations show that the accuracy can be improved by 41.2%after this treatment.For variable ocean crust density,simulation simulations verify that the root-mean-square(RMS)error of prediction is approximately 5 m for the sea depth of 6 km if density is chosen as the average one.Finally,two test regions in the South China Sea are predicted and compared with ship soundings data,RMS errors of predictions are 71.1 m and 91.4 m,respectively.展开更多
文摘AIM:To investigate the effect of using base-out prisms on nystagmus,visual acuity and contrast sensitivity in patients with albinism.METHODS:In this interventional study,patients with albinism who had nystagmus were enrolled.A comprehensive eye exam was conducted,which included refraction,assessment of far and near vision acuity,and contrast sensitivity measurements.To check for the nystagmus,a videonystagmography was used.The tests were carried out in three modes:without any correction,with optical correction,and with correction using base-out prisms in three different powers,including 4,6,and 8 prism diopters.RESULTS:Totally 23 patients with average age of 28.65±12.13 were examined.It was found that the use of optical correction and optical correction with prisms resulted in a statistically significant improvement in both far(at least:P<0.006)and near visual acuity(at least:P<0.001 except for prism 8;P<0.02).In addition,contrast sensitivity significantly improved at all low and medium frequencies except for correction with prism 8 in frequency 1.5(at least:P<0.01 except for prism 4,frequency 6;P=0.04).no significant improvement was observed in the evaluation of nystagmus characteristics.CONCLUSION:Optical correction with a prism can improve visual acuity and some spatial frequencies,but failed to improve nystagmus parameters.
文摘The achievements made in China in the field of the theory of conjugation for reflecting prisms are outlined which mainly includes 6 theorems, 2 corollaries, over 30 formulae, 4 matric operators, 20 characteristic parameters, a new principle for dassification, and a new system of graphical tabulation for reflecting prisms. As an approach to developing the theory, an imaginary physical model called 'rigid body's kinematics model' has been creatively initiated to simulate the real physical phenomena of both image formation and image motion for reflecting prisms. Such a method of treatment has been successfully making the evolving theory more complete, more systematic, more generalized, and unique as well.
文摘·AIM: To evaluate the efficacy of a new modality for improving visual acuity (VA) in pediatric patients with anisometropic amblyopia. · METHODS: Retrospective and interventional case series. Medical records of 360 children with anisometropic amblyopia treated with a modality that included rotated prisms, lenses, and near activities from January 2008 to January 2012 were analyzed. Characteristics such as improvement of VA and contrast sensitivity in amblyopic eyes and resolution of amblyopia (VA ≤ 0.1logMAR or a difference of ≤ 2 lines in logMAR between the eyes) were assessed. ·RESULTS: Among the patients, the mean VA of the amblyopic eyes improved from 0.48logMAR (SD=0.16) to 0.12logMAR (SD =0.16) and the mean VA improvement was 0.36logMAR (SD =0.10, P【0.001). Resolution of amblyopia was achieved in 233 of 360 patients (64.72%). The mean time for resolution of amblyopia was 8.05 weeks (SD=4.83) or 14.14 sessions (SD=8.76). Among the study group, refraction error did not change significantly after treatment (P=0.437). We found that better baseline VA may be related to success and shorten the time to amblyopic resolution. ·CONCLUSION: VA and contrast sensitivity improved with rotated prisms, correcting lenses, and near activities in children with anisometropic amblyopia. The VA improvement by this modality was comparable to other methods. However, the time to resolution of amblyopia was shorter with this method than with other modalities. Rotated prisms combined with near acuity could provide an alternative treatment in children with anisometropic amblyopia who can’t tolerant traditional therapy method like patching.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61875148)。
文摘We systematically investigate the power distribution characteristics of microjets generated by prismatic scatterers with different shapes at sub-THz region(λ = 8.57 mm). Among these prismatic scatterers, the hexagonal-type one shows better focusing feature than the others. Aiming at the hexagonal-type one, we propose a double-layer scatterer composed of a Teflon hexagonal prism as an outer layer and a semiconductor cuboid as an inner layer. Aiming at the double-layer scatterer, we further study the effects of refractive index, size, and shape of the inner cuboid on microjet’s features. The study allows us to present an optimized double-layer scatterer, which has a side length λ/2(λ) and a refractive index 2.0(1.4) for the inner(outer) layer. We show that the optimized scatterer can produce an ultra-strong, ultra-narrow microjet with a power enhancement of;0 and a full width at half maximum(FWHM) of;0.26λ, and the microjet is just located at the output face. The microjet keeps compact within the distance range of λ from the output face. These features and effects are explained from the viewpoint of ray optics theory. According to the optimized double-layer scatterer, we further study the multi-frequency focusing features of the microjets, and find that the microjet remains good features at harmonic frequencies 2f_(0) and 3f_(0). In addition, we investigate the effect of an Au sphere presence in the center of the microjet on the power distribution. The results show that a spherical dark spot with a size similar to that of the Au sphere emerges in the area where the Au sphere is placed. The feature can be used to measure the size of a metallic particle.
文摘Hands-on Mini Lab Work with a partner.·Use the cubes to build a rectangular prism with a length of 8 centimeters.·Count the number of squares on each face.The sum is the surface area.1.Record the dimensions,volume,and surface area in a table.2.Build two more prisms using all of the cubes.For each,record the dimensions,volume,and surface area.3.Describe the rectangular prisms with the greatest and least surface areas.
文摘The influence of the refractive index n2 of optical cement on the structure angle, field angle, and transmission of Glan-Thompson prism has been studied in detail. The results show that the structure angle will increase with the decrease of n2 under the condition of the largest field angle. Thus, the ratio of length to width （L/A） of the prism will decrease, which means more materials can be saved. When the value of L/A is 3.0 or 2.5 in the routine design, the field angle will firstly increase and then decrease with the increment of n2. Two routine designs with the n2 values of 1.47 and 1.45 have the optimal field angle. In addition, n2 also has great influence on light intensity transmittance of the prism. Considering all these factors, it will be the best choice with L/A = 2.5 and n2 = 1.45 - 1.46.
基金supported by the National High-Tech Committee of Chinathe National Nature Science Foundation of China
文摘The dispersion of a pair of prisms is analyzed by means of a ray-tracing method operating at other than tip-to-tip propagation of the prisms, taking into consideration the limited spectral bandwidth. The variations of the group delay dispersion and the third-order dispersion for a pair of prisms are calculated with respect to the incident position and the separation between the prisms. The pair of prisms can provide a wide range of independent and continuous third-order dispersion compensation. The effect of residual third-order dispersion on the pulse contrast ratio and pulse duration is also calculated. The residual third-order dispersion not only worsens the pulse contrast ratio, but also increases the pulse duration to the hundreds of femtosecond range for a tens of femtosecond pulse, even when the residual thirdorder dispersion is small. These phenomena are helpful in compensating for the residual high-order dispersion and in understanding its effect on pulse contrast ratios and pulse durations in ultrashort laser systems.
基金National Natural Science Foundation of China for funding support via grant No 12175013the Interdisciplinary Research Project for Young Researchers of USTB and the Youth Teacher International Exchange&Growth Program of USTB(Fundamental Research Funds for the Central Universities,China)for funding support via grant No FRF-IDRY-21–018 and QNXM20250033,respectively.
文摘Evaluation of damage evolution effects in biodegradable pure Mg was carried out,using transmission electron microscope as surrogate irradiation for high-energy radionuclide β decay in Brachytherapy.Time-dependent quantitative defect production,evolution dynamics,and evolution statistics were revealed in-situ for two prism foils(z=[1.210],[10.10]),in as-received and heat-treated pure Mg,after 300 keV electron irradiation up to 0.468 dpa at R.T.Preferred nucleation of basal-plane interstitial-type 1/6<20.23>loops was confirmed,in addition to a small portion of prism-plane 1/3<11.20>loops.No cavities were found.A higher yield of point defect concentration and a more evident trend of defect coarsening were identified in[1.210]than in[10.10].Pre-existing dislocations(on the orders of 10^(13)−10^(14) m^(−2))in pure Mg resulted in a delay of the first occurrence of visible defects.Defect migration and elastic interactions governed the microstructural evolution of electron irradiation damage in pure Mg,giving rise to events of loop coalescence,growth,and sometimes rotation of habit plane.The influence of incident electron energy can be correlated to the rates of point defect production,and is quantifiable;however,interfered by defect cluster stability,defect mobility,and defect interactions.This forms an important theoretical basis for the application of Mg subjected to MeV-level β-decay radiation in Brachytherapy.The paper concludes with a brief comparison between Mg and conventional Ti casing,outlines the advantages and challenges,and provides reference points for the validation of Mg/Mg-alloys in Brachytherapy seed application.
基金This research was supported by the NSFC grant(No.92255303)The first author is grateful for support from the IGGCAS postdoctoral program(2016IFPR01)under the guidance of Prof.Bo Wan.
文摘Arc-continent collision zones are critical areas where uplift,accretion,and erosion processes significantly influence the growth,elimination,or recycling of the continental crust.The Zagros–Makran Transition Zone,located along the Minab-Zendan Fault,represents a convergence boundary between the Zagros continental domain and the Makran accretionary prism in southern Iran from the Cretaceous onwards.Several tectonic slices,including Neotethys ophiolitic remnants and the Ganj and Bajgan-Durkan complexes,have accreted along the southern margin of the Eurasian Plate during subduction in the western Makran wedge.To clarify the growth steps of the Makran Prism and the internal deformation associated with arc-continent collision,we used a provenance study of sandstones from the western Makran accretionary prism involving petrography of the main detrital components and U–Pb dating,Hf isotopic values,and trace elements of detrital zircon grains.Our findings reveal a progressive scenario in which oceanic arc-related rocks of the∼99 Ma Ganj Complex with Hf values ranging from+10 to+16 were uplifted during the Early to Late Eocene.The Eocene fore-arc sediments were sourced from the∼49–47 Ma Urumieh-Dokhtar Magmatic Arc with Hf values between−5 and+12,as well as from the Ganj Complex.The Jurassic–Cretaceous Bajgan-Durkan Complex was uplifted due to the Late Eocene to Oligocene collision of various terranes along the southern margin of the Eurasian Plate.This led to a major sediment influx into the Makran trench with a detrital signal in the range∼175–160 Ma with Hf isotopic values from−3 to+4 and alongside the Urumieh-Dokhtar Magmatic Arc with detrital ages ranging∼46–37 Ma and ca.80 Ma.Notably,metamorphic lithic grains began to appear in the sediments in the Late Eocene.The initial arrival of sediments from the Arabian margin to the arc-continent suture zone along the Minab-Zendan Fault indicates the onset of initial collision.During the Late Oligocene–Early Miocene,detrital zircon ages in the range of∼610–520 Ma,sourced from the Arabian basement,were deposited in the trench basin together with components from the Eocene Urumieh-Dokhtar Magmatic Arc and Cretaceous ophiolitic clasts of∼93 Ma with Hf isotopic values of+12 to+16.Following the development and uplift of the orogen from the Middle Miocene onward,detrital zircon grains from the Cretaceous–Miocene Urumieh-Dokhtar Magmatic Arc,Jurassic–Cretaceous Bajgan-Durkan Complex,and Cretaceous ophiolites are present in both the Makran and Zagros sedimentary domains.
基金supported by the Dutch Research Council(NWO no.438-18-401).
文摘Space-time prism(STP)is a fundamental concept in time geography and has been predominately constructed in unimodal transportation networks.Due to the vast trip chaining options by private vehicles and public transportation,it was challenging to construct STP over multimodal transportation networks.We previously put forward an efficient method to narrow down the action space for trip chaining and construct STPs effectively in a multimodal supernetwork.This study applies multimodal STP modeling to measure space-time accessibility and equality of daily activity opportunities.Two equality measures(Gini coefficient and 20:20 ratio)are derived from two space-time accessibility measures based on delineated STPs.We examine the equality of access to shopping and leisure opportunities in the Rotterdam-The Hague metropolitan area,the Netherlands.The results show the effects of various factors on accessibility and equality.It is found that although the study area has relatively low inequality using single modes,multimodal trip chaining further reduces inequality to access the distributed space-time opportunities.
基金funded jointly by the National Nature Science Funds of China(No.42274010)the Fundamental Research Funds for the Central Universities(Nos.2023000540,2023000407).
文摘The prediction of bathymetry has advanced significantly with the development of satellite altimetry.However,the majority of its data originate from marine gravity anomaly.In this study,based on the expression of vertical gravity gradient(VGG)of a rectangular prism,the governing equations for determining sea depths to invert bathymetry.The governing equation is solved by linearization through an iterative process,and numerical simulations verify its algorithm and its stability.We also study the processing methods of different interference errors.The regularization method improves the stability of the inversion process for errors.A piecewise bilinear interpolation function roughly replaces the low-frequency error,and numerical simulations show that the accuracy can be improved by 41.2%after this treatment.For variable ocean crust density,simulation simulations verify that the root-mean-square(RMS)error of prediction is approximately 5 m for the sea depth of 6 km if density is chosen as the average one.Finally,two test regions in the South China Sea are predicted and compared with ship soundings data,RMS errors of predictions are 71.1 m and 91.4 m,respectively.
