The accurate identification of microporosity is crucial for the characterization of hydrocarbon reservoir permeability and production.Scanning electron microscopy(SEM)is among the limited number of methods available t...The accurate identification of microporosity is crucial for the characterization of hydrocarbon reservoir permeability and production.Scanning electron microscopy(SEM)is among the limited number of methods available to directly observe the microscopic structure of the hydrocarbon reservoir rocks.Nevertheless,precise segmentation of microscopic pores at different depths in SEM images remains an unsolved challenge,known as the‘depth-related resolution loss'problem.Therefore,in this study,a 3D reconstruction technique for regions of interest(ROI)was developed for in-depth pixel analysis and differentiation among various depths of SEM images.The processed SEM images,together with the processing outcomes of this technique,were used as the input database to train a stochastic depth with multi-channel residual pathways(SdstMcrp)deep learning model programmed in Python to develop a tool for segmenting the microscopic pore spaces in SEM images obtained from the Beibuwan Basin.The more accurate segmentation helped to detect an average of 1.2 times more microporosity in SEM images,accounting for about 1.6 times more pixels and 1.2 times more pore surface area.Finally,the impact of the accurate segmentation on the calculation of permeability,a significant reservoir production property,was investigated using fractal geometry models and sensitivity analysis.The results showed that the obtained permeability values would vary by a factor of 6,which represents a considerable difference.These findings demonstrate that the proposed models can effectively identify features across a wide range of grayscale values in SEM images.展开更多
This study investigates the seismic performance of multiple reinforcement,high-strength concrete(MRHSC)columns that are characterized by multiple transverse and longitudinal reinforcements in core areas.Eight MRHSC co...This study investigates the seismic performance of multiple reinforcement,high-strength concrete(MRHSC)columns that are characterized by multiple transverse and longitudinal reinforcements in core areas.Eight MRHSC columns were designed and subjected to a low cycle,reversed loading test.The response,including the failure modes,hysteretic behavior,lateral bearing capacity,and displacement ductility,was analyzed.The effects of the axial compression ratio,stirrup form,and stirrup spacing of the central reinforcement configuration on the seismic performance of the columns were studied.Furthermore,an analytical model was developed to predict the backbone force-displacement curves of the MRHSC columns.The test results showed that these columns experienced two failure modes:shear failure and flexure-shear failure.As the axial compression ratio increased,the bearing capacity increased significantly,whereas the deformation capacity and ductility decreased.A decrease in the spacing of central transverse reinforcements improved the ductility and delayed the degradation of load-bearing capacity.The proposed analytical model can accurately predict the lateral force and deformations of MRHSC columns.展开更多
Considering the range anxiety issue caused by the limited driving range and the scarcity of battery charging stations,the conventional multinomial logit(MNL)model with the overlapping path issue was used in route choi...Considering the range anxiety issue caused by the limited driving range and the scarcity of battery charging stations,the conventional multinomial logit(MNL)model with the overlapping path issue was used in route choice modeling to describe the route choice behavior of travelers effectively.Furthermore,the generalized nested logit-based stochastic user equilibrium(GNL-SUE)model with the constraints of multiple user classes and distance limits was proposed.A mathematical model was developed and solved by the method of successive averages.The mathematical model was proven to be analytically equivalent to the modified GNL-SUE model,and the uniqueness of the solution was also confirmed.The proposed mathematical model was tested and compared with the GNL-SUE model without a distance limit and the MNL-SUE model with a distance limit.Results show that the proposed mathematical model can effectively handle the range anxiety and overlapping path challenges.展开更多
When a coin is tossed to a gravity well,it will spiral instead of falling directly to the center.Inspired by this phenomenon,a gravity well-inspired double friction pendulum system(GW-DFPS)is developed to extend the l...When a coin is tossed to a gravity well,it will spiral instead of falling directly to the center.Inspired by this phenomenon,a gravity well-inspired double friction pendulum system(GW-DFPS)is developed to extend the length of sliding trajectories of bridge superstructures during pulse-like near-fault earthquakes.As a result,a greater amount of energy will be dissipated due to the frictional sliding of the isolators.The GW-DFPS consists of a spherical surface and an outer surface described by a 1/x or logarithmic function to build gravity well.Full-scale isolators were fabricated and their response was characterized considering various parameters such as the friction material of slider,surface roughness of sliding surfaces,and applied vertical loads.Additionally,a finite element model of the isolator was created using the experimental test data.Numerical simulations were performed on a case-study bridge structure isolated using both a conventional DFPS system and the proposed GW-DFPS systems.The experimental results reveal that the proposed isolators exhibit stable response under vertical loads varying from 200 kN to 1000 kN with a negative stiffness response when the isolator slides at the outer sliding surface.The numerical simulations of the selected bridge structure demonstrate that the GW-DFPS significantly extends the sliding trajectory lengths of the superstructure during half of the earthquake pulses,resulting in increased energy dissipation during this interval.The kinetic energies of the bridge isolated by GW-DFPS are consistently lower than those of the bridge isolated by the other two kinds of isolators,resulting lower shear forces on the bridge.展开更多
Obsolescence of integrated systems which contain hardware and software is a problem that affects multiple industries and can occur for many reasons,including technological,economic,organizational,and social factors.It...Obsolescence of integrated systems which contain hardware and software is a problem that affects multiple industries and can occur for many reasons,including technological,economic,organizational,and social factors.It is especially acute in products and systems that have long life cycles,where a high rate of technological innovation of the subcomponents result in a mismatch in life cycles between the components and the systems.While several approaches for obsolescence forecasting exist,they often require data that may not be available.This paper describes an approach using non-probabilistic scenarios coupled with decision analysis to investigate how particular scenarios influence priority setting for products and systems.Scenarios are generated from a list of emergent and future conditions related to obsolescence.The key result is an identification of the most and least disruptive scenarios to the decision maker’s priorities.An example is presented related to the selection of technologies for energy islanding,which demonstrates the methodology using six obsolescence scenarios.The paper should be of broad interest to scholars and practitioners engaged with enterprise risk management and similar challenges of large-scale systems.展开更多
In the United States, emission regulations are enacted at a state level;individual states are allowed to define what methods they will use to mitigate their carbon emissions. The consequence of this is especially inte...In the United States, emission regulations are enacted at a state level;individual states are allowed to define what methods they will use to mitigate their carbon emissions. The consequence of this is especially interesting in the state of Texas where new legislation has created a “deregulated” electricity market in which end-users are capable of choosing their electricity provider and subsequently the type of electricity they wish to consume (generated by fossil fuels or renewable sources). In this paper we analyze the effects of carbon tax on the development of renewable generation capacity at the utility level while taking into account expected adoption of rooftop PV systems by individual consumers using agent based modeling techniques. Monte Carlo simulations show carbon abatement trends and proffer updated renewable portfolio standards at various levels of likelihood.展开更多
Long-term droughts significantly impact surface and groundwater resources in India,however,observed changes in major river basins have not been well explored.Here we use Standardized Precipitation Index(SPI)and Standa...Long-term droughts significantly impact surface and groundwater resources in India,however,observed changes in major river basins have not been well explored.Here we use Standardized Precipitation Index(SPI)and Standardized Precipitation Evapotranspiration Index(SPEI)at three different time scales(24,48,and 60 months)to identify long-term droughts in India for the observed record of 1951-2015.Drought characteristics(extent,events,frequency,and intensity)are analyzed for different river basins in India.Increasing trend in the areal extent of droughts is observed in two methods with three time scales in the maximum area(63.66%)in India.We use the data from the Gravity Recovery and Climate Experiment(GRACE)to estimate the changes in the terrestrial water storage(TWS)during the period 2002-2015.We identify that major long-term droughts in India occurred from 1966 to 1969,1972,1986-1987,and 2002-2004.The all-India average TWS shows a negative trend from 2002 to 2015 with prominent decline in north Indian river basins and positive trend in south Indian river basins.SPI and SPEI at longer time scales are positively associated with TWS indicating the adverse impacts of droughts on surface and groundwater resources in such a populated region.展开更多
Life cycle assessments(LCAs)of early-stage technologies can provide valuable insights about key drivers of emissions and aid in prioritizing research into further emissions-reduction opportunities.Despite this potenti...Life cycle assessments(LCAs)of early-stage technologies can provide valuable insights about key drivers of emissions and aid in prioritizing research into further emissions-reduction opportunities.Despite this potential value,further development of LCA methods is required to handle the increased uncertainty,data gaps,and confidentially of early-stage data.This study presents a discussion of the life cycle carbon footprinting of technologies competing in the final round of the NRG COSIA Carbon XPRIZE competition-a US$20 million competition for teams to demonstrate the conversion of CO_(2) into valuable products at the scale of a small industrial pilot using consistent deployment conditions,boundaries,and methodological assumptions.This competition allowed the exploration of how LCA can be used and further improved when assessing disparate and early-stage technologies.Carbon intensity estimates are presented for two conversion pathways:(i)CO_(2) mineralization and(ii)catalytic conversion(including thermochemical,electrochemical,photocatalytic and hybrid process)of CO_(2),aggregated across teams to highlight the range of emissions intensities demonstrated at the pilot for individual life cycle stages.A future scenario is also presented,demonstrating the incremental technology and deployment conditions that would enable a team to become carbon-avoiding relative to an incumbent process(i.e.reducing emissions relative to a reference pathway producing a comparable product).By considering the assessment process across a diverse set of teams,conversion pathways and products,the study presents generalized insights about opportunities and challenges facing carbon capture and-utilization technologies in their next phases of deployment from a life cycle perspective.展开更多
基金the Natural Science Foundation of Shandong Province of China(Nos.ZR2022QD080 , ZR2025MS575)the National Natural Science Foundation of China(Nos.W25322063,42250410333,52250410357)+1 种基金the Fundamental Research Funds for the Central Universities,CHD(No.300102263103)the Young Talent Fund of Association for Science and Technology in Shaanxi,China(No.20230703)。
文摘The accurate identification of microporosity is crucial for the characterization of hydrocarbon reservoir permeability and production.Scanning electron microscopy(SEM)is among the limited number of methods available to directly observe the microscopic structure of the hydrocarbon reservoir rocks.Nevertheless,precise segmentation of microscopic pores at different depths in SEM images remains an unsolved challenge,known as the‘depth-related resolution loss'problem.Therefore,in this study,a 3D reconstruction technique for regions of interest(ROI)was developed for in-depth pixel analysis and differentiation among various depths of SEM images.The processed SEM images,together with the processing outcomes of this technique,were used as the input database to train a stochastic depth with multi-channel residual pathways(SdstMcrp)deep learning model programmed in Python to develop a tool for segmenting the microscopic pore spaces in SEM images obtained from the Beibuwan Basin.The more accurate segmentation helped to detect an average of 1.2 times more microporosity in SEM images,accounting for about 1.6 times more pixels and 1.2 times more pore surface area.Finally,the impact of the accurate segmentation on the calculation of permeability,a significant reservoir production property,was investigated using fractal geometry models and sensitivity analysis.The results showed that the obtained permeability values would vary by a factor of 6,which represents a considerable difference.These findings demonstrate that the proposed models can effectively identify features across a wide range of grayscale values in SEM images.
基金Natural Science Foundation of China(NSFC)under Grant No.51868073Special Funds for Technology Innovation Guidance of Shaanxi under Grant No.2019CGHJ-06+1 种基金Natural Science Foundation of Shaanxi under Grant No.2018JQ5005Special Fund for Basic Scientific Research of Central Colleges under Grant No.300102288302。
文摘This study investigates the seismic performance of multiple reinforcement,high-strength concrete(MRHSC)columns that are characterized by multiple transverse and longitudinal reinforcements in core areas.Eight MRHSC columns were designed and subjected to a low cycle,reversed loading test.The response,including the failure modes,hysteretic behavior,lateral bearing capacity,and displacement ductility,was analyzed.The effects of the axial compression ratio,stirrup form,and stirrup spacing of the central reinforcement configuration on the seismic performance of the columns were studied.Furthermore,an analytical model was developed to predict the backbone force-displacement curves of the MRHSC columns.The test results showed that these columns experienced two failure modes:shear failure and flexure-shear failure.As the axial compression ratio increased,the bearing capacity increased significantly,whereas the deformation capacity and ductility decreased.A decrease in the spacing of central transverse reinforcements improved the ductility and delayed the degradation of load-bearing capacity.The proposed analytical model can accurately predict the lateral force and deformations of MRHSC columns.
基金The Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYLX16_0271).
文摘Considering the range anxiety issue caused by the limited driving range and the scarcity of battery charging stations,the conventional multinomial logit(MNL)model with the overlapping path issue was used in route choice modeling to describe the route choice behavior of travelers effectively.Furthermore,the generalized nested logit-based stochastic user equilibrium(GNL-SUE)model with the constraints of multiple user classes and distance limits was proposed.A mathematical model was developed and solved by the method of successive averages.The mathematical model was proven to be analytically equivalent to the modified GNL-SUE model,and the uniqueness of the solution was also confirmed.The proposed mathematical model was tested and compared with the GNL-SUE model without a distance limit and the MNL-SUE model with a distance limit.Results show that the proposed mathematical model can effectively handle the range anxiety and overlapping path challenges.
基金financially supported by the National Natural Science Foundation of China(Grants 52178124,52478151).
文摘When a coin is tossed to a gravity well,it will spiral instead of falling directly to the center.Inspired by this phenomenon,a gravity well-inspired double friction pendulum system(GW-DFPS)is developed to extend the length of sliding trajectories of bridge superstructures during pulse-like near-fault earthquakes.As a result,a greater amount of energy will be dissipated due to the frictional sliding of the isolators.The GW-DFPS consists of a spherical surface and an outer surface described by a 1/x or logarithmic function to build gravity well.Full-scale isolators were fabricated and their response was characterized considering various parameters such as the friction material of slider,surface roughness of sliding surfaces,and applied vertical loads.Additionally,a finite element model of the isolator was created using the experimental test data.Numerical simulations were performed on a case-study bridge structure isolated using both a conventional DFPS system and the proposed GW-DFPS systems.The experimental results reveal that the proposed isolators exhibit stable response under vertical loads varying from 200 kN to 1000 kN with a negative stiffness response when the isolator slides at the outer sliding surface.The numerical simulations of the selected bridge structure demonstrate that the GW-DFPS significantly extends the sliding trajectory lengths of the superstructure during half of the earthquake pulses,resulting in increased energy dissipation during this interval.The kinetic energies of the bridge isolated by GW-DFPS are consistently lower than those of the bridge isolated by the other two kinds of isolators,resulting lower shear forces on the bridge.
基金This work was supported in part by the National Science Foundation Grant 1747767"Planning IUCRC University of Virginia:Center for Hardware and Embedded System Security and Trust(CHEST)",and in part by the Commonwealth Center for Advanced Logistics Systems(CCALS).
文摘Obsolescence of integrated systems which contain hardware and software is a problem that affects multiple industries and can occur for many reasons,including technological,economic,organizational,and social factors.It is especially acute in products and systems that have long life cycles,where a high rate of technological innovation of the subcomponents result in a mismatch in life cycles between the components and the systems.While several approaches for obsolescence forecasting exist,they often require data that may not be available.This paper describes an approach using non-probabilistic scenarios coupled with decision analysis to investigate how particular scenarios influence priority setting for products and systems.Scenarios are generated from a list of emergent and future conditions related to obsolescence.The key result is an identification of the most and least disruptive scenarios to the decision maker’s priorities.An example is presented related to the selection of technologies for energy islanding,which demonstrates the methodology using six obsolescence scenarios.The paper should be of broad interest to scholars and practitioners engaged with enterprise risk management and similar challenges of large-scale systems.
文摘In the United States, emission regulations are enacted at a state level;individual states are allowed to define what methods they will use to mitigate their carbon emissions. The consequence of this is especially interesting in the state of Texas where new legislation has created a “deregulated” electricity market in which end-users are capable of choosing their electricity provider and subsequently the type of electricity they wish to consume (generated by fossil fuels or renewable sources). In this paper we analyze the effects of carbon tax on the development of renewable generation capacity at the utility level while taking into account expected adoption of rooftop PV systems by individual consumers using agent based modeling techniques. Monte Carlo simulations show carbon abatement trends and proffer updated renewable portfolio standards at various levels of likelihood.
文摘Long-term droughts significantly impact surface and groundwater resources in India,however,observed changes in major river basins have not been well explored.Here we use Standardized Precipitation Index(SPI)and Standardized Precipitation Evapotranspiration Index(SPEI)at three different time scales(24,48,and 60 months)to identify long-term droughts in India for the observed record of 1951-2015.Drought characteristics(extent,events,frequency,and intensity)are analyzed for different river basins in India.Increasing trend in the areal extent of droughts is observed in two methods with three time scales in the maximum area(63.66%)in India.We use the data from the Gravity Recovery and Climate Experiment(GRACE)to estimate the changes in the terrestrial water storage(TWS)during the period 2002-2015.We identify that major long-term droughts in India occurred from 1966 to 1969,1972,1986-1987,and 2002-2004.The all-India average TWS shows a negative trend from 2002 to 2015 with prominent decline in north Indian river basins and positive trend in south Indian river basins.SPI and SPEI at longer time scales are positively associated with TWS indicating the adverse impacts of droughts on surface and groundwater resources in such a populated region.
基金Funding for the study was provided by the XPRIZE Foundation.
文摘Life cycle assessments(LCAs)of early-stage technologies can provide valuable insights about key drivers of emissions and aid in prioritizing research into further emissions-reduction opportunities.Despite this potential value,further development of LCA methods is required to handle the increased uncertainty,data gaps,and confidentially of early-stage data.This study presents a discussion of the life cycle carbon footprinting of technologies competing in the final round of the NRG COSIA Carbon XPRIZE competition-a US$20 million competition for teams to demonstrate the conversion of CO_(2) into valuable products at the scale of a small industrial pilot using consistent deployment conditions,boundaries,and methodological assumptions.This competition allowed the exploration of how LCA can be used and further improved when assessing disparate and early-stage technologies.Carbon intensity estimates are presented for two conversion pathways:(i)CO_(2) mineralization and(ii)catalytic conversion(including thermochemical,electrochemical,photocatalytic and hybrid process)of CO_(2),aggregated across teams to highlight the range of emissions intensities demonstrated at the pilot for individual life cycle stages.A future scenario is also presented,demonstrating the incremental technology and deployment conditions that would enable a team to become carbon-avoiding relative to an incumbent process(i.e.reducing emissions relative to a reference pathway producing a comparable product).By considering the assessment process across a diverse set of teams,conversion pathways and products,the study presents generalized insights about opportunities and challenges facing carbon capture and-utilization technologies in their next phases of deployment from a life cycle perspective.
