Identifying how leaf habit subdivisions link to the fast–slow and avoidance–tolerance trait tradeoffs can provide new insight into divergence in ecophysiological strategies among plant functional groups. Here, we te...Identifying how leaf habit subdivisions link to the fast–slow and avoidance–tolerance trait tradeoffs can provide new insight into divergence in ecophysiological strategies among plant functional groups. Here, we tested a hypothesis that the differentiation across deciduous, semi-deciduous and evergreen woody species contributes to physiological trait tradeoffs in a dry-hot valley savanna. We investigated 11 photosynthetic, morphological and hydraulic traits of 24 species including 8 deciduous, 10 semi-deciduous and 6 evergreen species. Deciduous species were grouped in the fast and avoidance side associated with high values of maximum photosynthetic rates,stomatal conductance and leaf size, while evergreen species were grouped in the slow and tolerance side associated with high photosynthetic water use efficiency, leaf mass per area, sapwood density, Huber value, leaf water potential at turgor loss point and water potential causing 50% loss of stem hydraulic conductance. Semideciduous species generally had intermediate trait values and represented different physiological characteristics when compared to deciduous and evergreen species. The physiological trait tradeoffs showed a close linkage to the differentiation of these three leaf habits. Our findings clearly reveal trait tradeoffs related to fast–slow and avoidance–tolerance strategies among diverse savanna plants, suggesting a syndrome in multiple ecophysiology strategies across different leaf habits.展开更多
Deciduous oaks(Quercus spp.)are distributed from subalpine to tropical regions in the northern hemi-sphere and have important roles as carbon sinks and in climate change mitigation.Determining variations in plant func...Deciduous oaks(Quercus spp.)are distributed from subalpine to tropical regions in the northern hemi-sphere and have important roles as carbon sinks and in climate change mitigation.Determining variations in plant functional traits at multiple biological levels and linking them to environmental variables across geographical ranges is important for forecasting range-shifts of broadly-distrib-uted species under climate change.We sampled leaves of five deciduous Quercus spp.covering approximately 20°of latitude(~21°N-41°N)and 20 longitude(~99°E-119°E)across China and measured 12 plant functional traits at different biological levels.The traits varied distinctively,either within each biological level or among different levels driven by climatic and edaphic variables.Traits at the organ level were significantly correlated with those at the cellular and tissue levels,while traits at the whole-plant level only correlated with those at the tissue level.The Quercus species responded to changing environments by regulating stomatal size,leaf thickness and the palisade mesophyll thickness to leaf thickness ratios with contrasting degree of effect to adjust the whole-plant functioning,i.e.,intrinsic water use efficiency(iWUE),carbon supply and nitrogen availability.The results suggest that these deciduous Quercus spp.will maintain vigour by increasing iWUE when subjected to large temperature changes and insufficient moisture,and by accu-mulating leaf non-structural carbohydrates under drought conditions.The findings provide new insights into the inher-ent variation and trait coordination of widely distributed tree species in the context of climate change.展开更多
Remote sensing(RS)facilitates forest inventory across a wide range of variables required by the UNFCCC as well as by other agreements and processes.The Conventional model-based(CMB)estimator supports wall-to-wall RS d...Remote sensing(RS)facilitates forest inventory across a wide range of variables required by the UNFCCC as well as by other agreements and processes.The Conventional model-based(CMB)estimator supports wall-to-wall RS data,while Hybrid estimators support surveys where RS data are available as a sample.However,the connection between these two types of monitoring procedures has been unclear,hindering the reconciliation of wall-to-wall and non-wall-to-wall use of RS data in practical applications and thus potentially impeding cost-efficient deployment of high-end sensing instruments for large area monitoring.Consequently,our objectives are to(1)shed further light on the connections between different types of Hybrid estimators,and between CMB and Hybrid estimators,through mathematical analyses and Monte Carlo simulations;and(2)compare the effects and explore the tradeoffs related to the RS sampling design,coverage rate,and cluster size on estimation precision.Primary findings are threefold:(1)the CMB estimator represents a special case of Hybrid estimators,signifying that wallto-wall RS data is a particular instance of sample-based RS data;(2)the precision of estimators in forest inventory can be greater for stratified non-wall-to-wall RS data compared to wall-to-wall RS data;(3)otherwise costprohibitive sensing,such as LiDAR and UAV,can support large scale monitoring through collecting RS data as a sample.These conclusions may reconcile different perspectives regarding choice of RS instruments,data acquisition,and cost for continuous observations,particularly in the context of surveys aiming at providing data for mitigating climate change.展开更多
One of the most important characters of blasting,a basic step of surface mining,is rock fragmentation because it directly effects on the costs of drilling and economics of the subsequent operations of loading,hauling ...One of the most important characters of blasting,a basic step of surface mining,is rock fragmentation because it directly effects on the costs of drilling and economics of the subsequent operations of loading,hauling and crushing in mines.Adaptive neuro-fuzzy inference system(ANFIS)and radial basis function(RBF)show potentials for modeling the behavior of complex nonlinear processes such as those involved in fragmentation due to blasting of rocks.We developed ANFIS and RBF methods for modeling of sizing of rock fragmentation due to bench blasting by estimation of 80%passing size(K_(80))of Golgohar iron mine of Sirjan.Iran.Comparing the results of ANFIS and RBF models shows that although the statistical parameters RBF model is acceptable but ANFIS proposed model is superior and also simpler because ANFIS model is constructed using only two input parameters while seven input parameters used for construction of RBF model.展开更多
Changes in tree mortality due to severe drought can alter forest structure,composition,dynamics,ecosystem services,carbon fl uxes,and energy interactions between the atmosphere and land surfaces.We utilized long-term(...Changes in tree mortality due to severe drought can alter forest structure,composition,dynamics,ecosystem services,carbon fl uxes,and energy interactions between the atmosphere and land surfaces.We utilized long-term(2000‒2017,3 full inventory cycles)Forest Inventory and Analysis(FIA)data to examine tree mortality and biomass loss in drought-aff ected forests for East Texas,USA.Plots that experienced six or more years of droughts during those censuses were selected based on 12-month moderate drought severity[Standardized Precipitation Evaporation Index(SPEI)-1.0].Plots that experienced other disturbances and inconsistent records were excluded from the analysis.In total,222 plots were retained from nearly 4000 plots.Generalized nonlinear mixed models(GNMMs)were used to examine the changes in tree mortality and recruitment rates for selected plots.The results showed that tree mortality rates and biomass loss to mortality increased overall,and across tree sizes,dominant genera,height classes,and ecoregions.An average mortality rate of 5.89%year−1 during the study period could be incited by water stress created by the regional prolonged and episodic drought events.The overall plot and species-group level recruitment rates decreased during the study period.Forest mortality showed mixed results regarding basal area and forest density using all plots together and when analyzed the plots by stand origin and ecoregion.Higher mortality rates of smaller trees were detected and were likely compounded by densitydependent factors.Comparative analysis of drought-induced tree mortality using hydro-meteorological data along with drought severity and length gradient is suggested to better understand the eff ects of drought on tree mortality and biomass loss around and beyond East Texas in the southeastern United States.展开更多
Background Atrial fibrillation （AF） causes a continuum of atrial anatomical remodeling. Methods Using a library of perfusion-fixed human hearts, specimens with AF were compared to controls. During this preliminary a...Background Atrial fibrillation （AF） causes a continuum of atrial anatomical remodeling. Methods Using a library of perfusion-fixed human hearts, specimens with AF were compared to controls. During this preliminary assessment study, direct measurements were taken of atrial volume, pulmonary vein （PV） circumference, and left atrial （LA） wall thicknesses. Results Hearts with AF typically had larger atrial volumes, as well as a much larger variation in volume compared to controls （range of 59.6-227.1 mL in AF hearts compared to 65.1-115.9 mL in controls）. For all hearts, right PVs were larger than left PVs （mean： 171.4 ± 84.6 mm^2 for right and 1182 ± 50.1 mm^2 for left, P 〈 0.005）. LA wall thicknesses ranged from 0.7 mm to 3.1 mm for both AF and control hearts. Conclusions Hearts with AF had a large range of sizes which is consistent with the progression of atrial remodeling during AF. The large range of thicknesses will influence the amount of energy needed to create transmural lesions during ablation procedures.展开更多
A model on the coexisting phase of quasicrystal-crystal is proposed, with which we concretely investigate the inter- face effects for coexisting phases of one-dimensional orthorhombic quasicrystal-isotropic crystal an...A model on the coexisting phase of quasicrystal-crystal is proposed, with which we concretely investigate the inter- face effects for coexisting phases of one-dimensional orthorhombic quasicrystal-isotropic crystal and three-dimensional icosahedral quasierystal-cubic crystal. The phason strain fields which play an important role in some processes are determined. Some factors affecting the strain fields, e.g., the material constants of phonon, phason, phonon-phason coupling of the quasicrystal and the elastic modulus and the size of the crystal are also explored.展开更多
Acute upper gastrointestinal （GI） bleeding remains one of the most common encounters in emergency medicine. The increased use of non-steroid anti-inflammatory drugs by the general population and the increased prescr...Acute upper gastrointestinal （GI） bleeding remains one of the most common encounters in emergency medicine. The increased use of non-steroid anti-inflammatory drugs by the general population and the increased prescription of anti-platelet agents and anti-coagulants after cardiovascular interventions and for prevention of cerebral vascular accidents may have aggravated the situation. Significant progress has been made in the past decade or so in the non-surgical management of acute upper GI bleeding emergencies. This article will review the current standard treatment of the most common upper GI bleeding emergencies in adults as supported by evidence- based medicine with practical considerations from the authors＇ own practice experience.展开更多
This study investigated the effects of torrefaction with Mg(OH)2 on the properties of bio-oil formed from the microwave-assisted catalytic fast co-pyrolysis of straw stalk and soapstock.The effects of torrefaction tem...This study investigated the effects of torrefaction with Mg(OH)2 on the properties of bio-oil formed from the microwave-assisted catalytic fast co-pyrolysis of straw stalk and soapstock.The effects of torrefaction temperature and residence time on the yield and composition of bio-oil were discussed.Results showed that the torrefaction temperature and residence time remarkably influenced the yield and composition of bio-oil.With the increase in temperature and time,the bio-oil yield and the proportion of oxygen-containing compounds decreased,while the proportion of aromatic compounds increased.When the feedstocks were subject to torrefaction reaction for 20 min at 260°C,the proportion of oxygen-containing compounds decreased from 29.89%to 16.49%.Meanwhile,Mg(OH)2 could render the deoxidization function of torrefaction process increasingly noticeable.The proportion of the oxygen-containing compounds reached a minimum(14.41%),when the biomass-to-Mg(OH)2 ratio was 1:1.展开更多
Hydrogen is an indispensable energy carrier for the sustainable development of human society.Nevertheless,its storage,transportation,and in situ generation still face significant challenges.Methanol can be used as an ...Hydrogen is an indispensable energy carrier for the sustainable development of human society.Nevertheless,its storage,transportation,and in situ generation still face significant challenges.Methanol can be used as an intermediate carrier for hydrogen supplies,providing hydrogen energy through instant methanol conversion.In this study,a sorption-enhanced,chemical-looping,oxidative steam methanol-reforming(SECLOSRM)process is proposed using CuO–MgO for the on-board hydrogen supply,which could be a promising method for safe and efficient hydrogen production.Aspen Plus software was used for feasibility verification and parameter optimization of the SECL-OSRM process.The effects of CuO/CH_(3)OH,MgO/CH_(3)OH,and H_(2)O/CH_(3)OH mole ratios and of temperature on H_(2)production rate,H utilization efficiency,CH_(3)OH conversion,CO concentration,and system heat balance are discussed thoroughly.The results indicate that the system can be operated in autothermal conditions with high-purity hydrogen(99.50 vol%)and ultra-low-concentration CO(<50 ppm)generation,which confirms the possibility of integrating low-temperature proton-exchange membrane fuel cells(LT-PEFMCs)with the SECL-OSRM process.The simulation results indicate that the CO can be modulated in a lower concentration by reducing the temperature and by improving the H_(2)O/CH_(3)OH and MgO/CH_(3)OH mole ratios.展开更多
The influence of surface/interface roughness on the magnetic properties of Fe/Ni multilayers is investigated.Two methods are employed to tune the film roughness:one varies the substrate temperature,and the other pre-d...The influence of surface/interface roughness on the magnetic properties of Fe/Ni multilayers is investigated.Two methods are employed to tune the film roughness:one varies the substrate temperature,and the other pre-deposits a Ag underlayer on the MgO substrate.For films with higher roughness,a marked rise in coercivity is observed.Three factors are discussed to be mainly responsible for the coercivity rise,involving the formation of pinholes,the reduction of exchange coupling between Fe and Ni layers,and Fe-Ni alloying at interfaces.展开更多
Dye-sensitized solar cells(DSSCs) are one of the most promising renewable energy technologies. Charge transfer and charge transport are pivotal processes in DSSCs, which govern solar energy capture and conversion. The...Dye-sensitized solar cells(DSSCs) are one of the most promising renewable energy technologies. Charge transfer and charge transport are pivotal processes in DSSCs, which govern solar energy capture and conversion. These processes can be probed using modern electronic structure methods. Because of the heterogeneity and complexity of the local environment of a chromophore in DSSCs(such as solvatochromism and chromophore aggregation), a part of the solvation environment should be treated explicitly during the calculation. However, because of the high computational cost and unfavorable scaling with the number of electrons of high-level quantum mechanical methods, approaches to explicitly treat the local environment need careful consideration. Two problems must be tackled to reduce computational cost. First, the number of configurations representing the solvent distribution should be limited as much as possible. Second, the size of the explicit region should be kept relatively small. The purpose of this study is to develop efficient computational approaches to select representative configurations and to limit the explicit solvent region to reduce the computational cost for later(higher-level) quantum mechanical calculations. For this purpose, an ensemble of solvent configurations around a 1-methyl-8-oxyquinolinium betaine(QB) dye molecule was generated using Monte Carlo simulations and molecular mechanics force fields. Then, a fitness function was developed using data from inexpensive electronic structure calculations to reduce the number of configurations. Specific solvent molecules were also selected for explicit treatment based on a distance criterion, and those not selected were treated as background charges. The configurations and solvent molecules selected proved to be good representatives of the entire ensemble; thus, expensive electronic structure calculations need to be performed only on this subset of the system, which significantly reduces the computational cost.展开更多
Grain coalescence has been applied in many areas of nanofabrication technology, including modification of thinfilm properties, nanowelding, and self-assembly of nanostructures. However, very few systematic studies of ...Grain coalescence has been applied in many areas of nanofabrication technology, including modification of thinfilm properties, nanowelding, and self-assembly of nanostructures. However, very few systematic studies of selfassembly using the grain coalescence, especially for threedimensional(3D) nanostructures, exist at present. Here, we investigate the mechanism of plasma triggered grain coalescence to achieve the precise control of nanoscale phase and morphology of the grain coalescence induced by exothermic energy. Exothermic energy is generated through etching a silicon substrate via application of plasma. By tuning the plasma power and the flow rates of reactive gases, different etching rates and profiles can be achieved, resulting in various morphologies of grain coalescence. Balancing the isotropic/anisotropic substrate etching profile and the etching rate makes it possible to simultaneously release 2D nanostructures from the substrate and induce enough surface tension force,generated by grain coalescence, to form 3D nanostructures.Diverse morphologies of 3D nanostructures have been obtained by the grain coalescence, and a strategy to achieve self-assembly, resulting in desired 3D nanostructures, has been proposed and demonstrated.展开更多
Substrate-free films of N-4-n-butoxybenzylidene-4-n-octylaniline(40.8)show a fascinating interlayer interaction.This interaction significantly affects the next ordering transition,or the second hexatic-B order,upon co...Substrate-free films of N-4-n-butoxybenzylidene-4-n-octylaniline(40.8)show a fascinating interlayer interaction.This interaction significantly affects the next ordering transition,or the second hexatic-B order,upon cooling.The Landau-de Gennes theory is employed to model the effect of the enhanced order by surface-ordering field.Based on this model,it is found that the surface-order penetration depth to be less than one layer.展开更多
Traffic data collection is essential for performance assessment, safety improvement and road planning. While automated traffic data collection for highways is relatively mature, that for roundabouts is more challengin...Traffic data collection is essential for performance assessment, safety improvement and road planning. While automated traffic data collection for highways is relatively mature, that for roundabouts is more challenging due to more complex traffic scenes, data specifications and vehicle behavior. In this paper, the authors propose an automated traffic data collection system dedicated to roundabout scenes. The proposed system has mainly four steps of processing. First, camera calibration is performed for roundabout traffic scenes with a novel circle-based calibration algorithm. Second, the system uses enhanced Mixture of Gaussian algorithm with shaking removal for video segmentation, which can tolerate repeated camera displacements and background movements. Then, Kalman filtering, Kemel-based tracking and overlap-based opti- mization are employed to track vehicles while they are occluded and to derive the complete vehicle trajectories. The resulting vehicle trajectory of each individual vehicle gives the position, size, shape and speed of the vehicle at each time moment. Finally, a data mining algorithm is used to automatically extract the interested traffic data from the vehicle trajectories. The overall traffic data collection system has been implemented in software and runs on regular PC. The total processing time for a 3-hour video is currently 6 h. The automated traffic data collection system can significantly reduce cost and improve efficiency compared to manual data collection. The extracted traffic data have been compared to accurate manual measurements for 29 videos recorded on 29 different days, and an accuracy of more than 90% has been achieved.展开更多
Smart cities depend highly on an intelligent electrical networks to provide a reliable,safe,and clean power supplies.A smart grid achieves such aforementioned power supply by ensuring resilient energy delivery,which p...Smart cities depend highly on an intelligent electrical networks to provide a reliable,safe,and clean power supplies.A smart grid achieves such aforementioned power supply by ensuring resilient energy delivery,which presents opportunities to improve the cost-effectiveness of power supply and minimize environmental impacts.A systematic evaluation of the comprehensive benefits brought by smart grid to smart cities can provide necessary theoretical fundamentals for urban planning and construction towards a sustainable energy future.However,most of the present methods of assessing smart cities do not fully take into account the benefits expected from the smart grid.To comprehensively evaluate the development levels of smart cities while revealing the supporting roles of smart grids,this article proposes a model of smart city development needs from the perspective of residents’needs based on Maslow’s Hierarchy of Needs theory,which serves the primary purpose of building a smart city.By classifying and reintegrating the needs,an evaluation index system of smart grids supporting smart cities was further constructed.A case analysis concluded that smart grids,as an essential foundation and objective requirement for smart cities,are important in promoting scientific urban management,intelligent infrastructure,refined public services,efficient energy utilization,and industrial development and modernization.Further optimization suggestions were given to the city analyzed in the case include strengthening urban management and infrastructure constructions,such as electric vehicle charging facilities and wireless coverage.展开更多
A new approach to threshold resonance calculation by the complex scaling method is discussed.Application to scattering over a model potential barrier is presented and compared to a direct quantum scattering calculation.
The method for pyrolysis of biomass to manufacture hydrocarbon-rich fuel remains challenging in terms of conversion of multifunctional biomass with high oxygen content and low thermal stability into a high-quality com...The method for pyrolysis of biomass to manufacture hydrocarbon-rich fuel remains challenging in terms of conversion of multifunctional biomass with high oxygen content and low thermal stability into a high-quality compound, featuring high content of hydrocarbons, low oxygen content, few functional groups, and high thermal stability. This study offers a promising prospect to derive hydrocarbon-rich oil through microwave-assisted fast catalytic pyrolysis by improving the effective hydrogen to carbon ratio(H/Ceff) of the raw materials. The proposed technique can promote the production of high-quality bio-oil through the molecular sieve catalyzed reduction of oxygenated compounds and mutagenic polyaromatic hydrocarbons. This work aims to review and summarize the research progress on microwave copyrolysis and microwave catalytic copyrolysis to demonstrate their benefits on enhancement of bio-oils derived from the biomass. This review focuses on the potential of optimizing the H/Ceff ratio, the microwave absorbent, and the HZSM-5 catalyst during the microwave copyrolysis to produce the valuable liquid fuel. This paper also proposes future directions for the use of this technique to obtain high yields of bio-oils.展开更多
基金funded by the National Natural Science Foundation of China (31901285, 32171507, 31870385, 32301308)the CAS“Light of West China”programs to DY and JLZ+3 种基金the Yunnan Fundamental Research Projects (202001AU070128, 202401AT070230)the 14th Five-Year Plan of the Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences (XTBG-1450101)German Vargas G. was supported by the NOAA Climate and Global Change Postdoctoral Fellowship Programadministered by UCAR's Cooperative Programs for the Advancement of Earth System Science (CPAESS) under the NOAA Science Collaboration Program award#NA21OAR4310383。
文摘Identifying how leaf habit subdivisions link to the fast–slow and avoidance–tolerance trait tradeoffs can provide new insight into divergence in ecophysiological strategies among plant functional groups. Here, we tested a hypothesis that the differentiation across deciduous, semi-deciduous and evergreen woody species contributes to physiological trait tradeoffs in a dry-hot valley savanna. We investigated 11 photosynthetic, morphological and hydraulic traits of 24 species including 8 deciduous, 10 semi-deciduous and 6 evergreen species. Deciduous species were grouped in the fast and avoidance side associated with high values of maximum photosynthetic rates,stomatal conductance and leaf size, while evergreen species were grouped in the slow and tolerance side associated with high photosynthetic water use efficiency, leaf mass per area, sapwood density, Huber value, leaf water potential at turgor loss point and water potential causing 50% loss of stem hydraulic conductance. Semideciduous species generally had intermediate trait values and represented different physiological characteristics when compared to deciduous and evergreen species. The physiological trait tradeoffs showed a close linkage to the differentiation of these three leaf habits. Our findings clearly reveal trait tradeoffs related to fast–slow and avoidance–tolerance strategies among diverse savanna plants, suggesting a syndrome in multiple ecophysiology strategies across different leaf habits.
基金supported by the Key Area Research and Development Program of Guangdong Province(2022B1111230001)theScience and Technology Foundation of Guangxi Zhuang Autonomous Region(Guike AD23026080)+1 种基金the National Natural Science Founda tion of China(No.42071065)Natural Science Foundation of US(No.2021898).
文摘Deciduous oaks(Quercus spp.)are distributed from subalpine to tropical regions in the northern hemi-sphere and have important roles as carbon sinks and in climate change mitigation.Determining variations in plant functional traits at multiple biological levels and linking them to environmental variables across geographical ranges is important for forecasting range-shifts of broadly-distrib-uted species under climate change.We sampled leaves of five deciduous Quercus spp.covering approximately 20°of latitude(~21°N-41°N)and 20 longitude(~99°E-119°E)across China and measured 12 plant functional traits at different biological levels.The traits varied distinctively,either within each biological level or among different levels driven by climatic and edaphic variables.Traits at the organ level were significantly correlated with those at the cellular and tissue levels,while traits at the whole-plant level only correlated with those at the tissue level.The Quercus species responded to changing environments by regulating stomatal size,leaf thickness and the palisade mesophyll thickness to leaf thickness ratios with contrasting degree of effect to adjust the whole-plant functioning,i.e.,intrinsic water use efficiency(iWUE),carbon supply and nitrogen availability.The results suggest that these deciduous Quercus spp.will maintain vigour by increasing iWUE when subjected to large temperature changes and insufficient moisture,and by accu-mulating leaf non-structural carbohydrates under drought conditions.The findings provide new insights into the inher-ent variation and trait coordination of widely distributed tree species in the context of climate change.
基金supported by the National Social Science Fund of China(No.22BTJ005)the Key Project of National Key Research and Development Plan(No.2023YFF1304002-05)+1 种基金supported by the National Natural Science Foundation of China(No.32001252)the International Center for Bamboo and Rattan(Nos.1632022024,1632020029,1632021024).
文摘Remote sensing(RS)facilitates forest inventory across a wide range of variables required by the UNFCCC as well as by other agreements and processes.The Conventional model-based(CMB)estimator supports wall-to-wall RS data,while Hybrid estimators support surveys where RS data are available as a sample.However,the connection between these two types of monitoring procedures has been unclear,hindering the reconciliation of wall-to-wall and non-wall-to-wall use of RS data in practical applications and thus potentially impeding cost-efficient deployment of high-end sensing instruments for large area monitoring.Consequently,our objectives are to(1)shed further light on the connections between different types of Hybrid estimators,and between CMB and Hybrid estimators,through mathematical analyses and Monte Carlo simulations;and(2)compare the effects and explore the tradeoffs related to the RS sampling design,coverage rate,and cluster size on estimation precision.Primary findings are threefold:(1)the CMB estimator represents a special case of Hybrid estimators,signifying that wallto-wall RS data is a particular instance of sample-based RS data;(2)the precision of estimators in forest inventory can be greater for stratified non-wall-to-wall RS data compared to wall-to-wall RS data;(3)otherwise costprohibitive sensing,such as LiDAR and UAV,can support large scale monitoring through collecting RS data as a sample.These conclusions may reconcile different perspectives regarding choice of RS instruments,data acquisition,and cost for continuous observations,particularly in the context of surveys aiming at providing data for mitigating climate change.
基金financially supported by the Special Fund of Islamic Azad University,Malayer Branch(No.2293)
文摘One of the most important characters of blasting,a basic step of surface mining,is rock fragmentation because it directly effects on the costs of drilling and economics of the subsequent operations of loading,hauling and crushing in mines.Adaptive neuro-fuzzy inference system(ANFIS)and radial basis function(RBF)show potentials for modeling the behavior of complex nonlinear processes such as those involved in fragmentation due to blasting of rocks.We developed ANFIS and RBF methods for modeling of sizing of rock fragmentation due to bench blasting by estimation of 80%passing size(K_(80))of Golgohar iron mine of Sirjan.Iran.Comparing the results of ANFIS and RBF models shows that although the statistical parameters RBF model is acceptable but ANFIS proposed model is superior and also simpler because ANFIS model is constructed using only two input parameters while seven input parameters used for construction of RBF model.
文摘Changes in tree mortality due to severe drought can alter forest structure,composition,dynamics,ecosystem services,carbon fl uxes,and energy interactions between the atmosphere and land surfaces.We utilized long-term(2000‒2017,3 full inventory cycles)Forest Inventory and Analysis(FIA)data to examine tree mortality and biomass loss in drought-aff ected forests for East Texas,USA.Plots that experienced six or more years of droughts during those censuses were selected based on 12-month moderate drought severity[Standardized Precipitation Evaporation Index(SPEI)-1.0].Plots that experienced other disturbances and inconsistent records were excluded from the analysis.In total,222 plots were retained from nearly 4000 plots.Generalized nonlinear mixed models(GNMMs)were used to examine the changes in tree mortality and recruitment rates for selected plots.The results showed that tree mortality rates and biomass loss to mortality increased overall,and across tree sizes,dominant genera,height classes,and ecoregions.An average mortality rate of 5.89%year−1 during the study period could be incited by water stress created by the regional prolonged and episodic drought events.The overall plot and species-group level recruitment rates decreased during the study period.Forest mortality showed mixed results regarding basal area and forest density using all plots together and when analyzed the plots by stand origin and ecoregion.Higher mortality rates of smaller trees were detected and were likely compounded by densitydependent factors.Comparative analysis of drought-induced tree mortality using hydro-meteorological data along with drought severity and length gradient is suggested to better understand the eff ects of drought on tree mortality and biomass loss around and beyond East Texas in the southeastern United States.
文摘Background Atrial fibrillation （AF） causes a continuum of atrial anatomical remodeling. Methods Using a library of perfusion-fixed human hearts, specimens with AF were compared to controls. During this preliminary assessment study, direct measurements were taken of atrial volume, pulmonary vein （PV） circumference, and left atrial （LA） wall thicknesses. Results Hearts with AF typically had larger atrial volumes, as well as a much larger variation in volume compared to controls （range of 59.6-227.1 mL in AF hearts compared to 65.1-115.9 mL in controls）. For all hearts, right PVs were larger than left PVs （mean： 171.4 ± 84.6 mm^2 for right and 1182 ± 50.1 mm^2 for left, P 〈 0.005）. LA wall thicknesses ranged from 0.7 mm to 3.1 mm for both AF and control hearts. Conclusions Hearts with AF had a large range of sizes which is consistent with the progression of atrial remodeling during AF. The large range of thicknesses will influence the amount of energy needed to create transmural lesions during ablation procedures.
基金Project supported by the National Natural Science Foundation of China (Grant No.10672022)
文摘A model on the coexisting phase of quasicrystal-crystal is proposed, with which we concretely investigate the inter- face effects for coexisting phases of one-dimensional orthorhombic quasicrystal-isotropic crystal and three-dimensional icosahedral quasierystal-cubic crystal. The phason strain fields which play an important role in some processes are determined. Some factors affecting the strain fields, e.g., the material constants of phonon, phason, phonon-phason coupling of the quasicrystal and the elastic modulus and the size of the crystal are also explored.
文摘Acute upper gastrointestinal （GI） bleeding remains one of the most common encounters in emergency medicine. The increased use of non-steroid anti-inflammatory drugs by the general population and the increased prescription of anti-platelet agents and anti-coagulants after cardiovascular interventions and for prevention of cerebral vascular accidents may have aggravated the situation. Significant progress has been made in the past decade or so in the non-surgical management of acute upper GI bleeding emergencies. This article will review the current standard treatment of the most common upper GI bleeding emergencies in adults as supported by evidence- based medicine with practical considerations from the authors＇ own practice experience.
基金financial support from the National Natural Science Foundation of China (No. 21766019)the Key Research and Development Program of Jiangxi Province (20171BBF60023)+2 种基金the International Science & Technology Cooperation Project of China (2015DFA60170-4)the Science and Technology Research Project of Jiangxi Province Education Department (No. GJJ150213)the Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Program (No. Y707sb1001)
文摘This study investigated the effects of torrefaction with Mg(OH)2 on the properties of bio-oil formed from the microwave-assisted catalytic fast co-pyrolysis of straw stalk and soapstock.The effects of torrefaction temperature and residence time on the yield and composition of bio-oil were discussed.Results showed that the torrefaction temperature and residence time remarkably influenced the yield and composition of bio-oil.With the increase in temperature and time,the bio-oil yield and the proportion of oxygen-containing compounds decreased,while the proportion of aromatic compounds increased.When the feedstocks were subject to torrefaction reaction for 20 min at 260°C,the proportion of oxygen-containing compounds decreased from 29.89%to 16.49%.Meanwhile,Mg(OH)2 could render the deoxidization function of torrefaction process increasingly noticeable.The proportion of the oxygen-containing compounds reached a minimum(14.41%),when the biomass-to-Mg(OH)2 ratio was 1:1.
基金supported by the National Key R&D Program of China(2018YFE0111100)National Natural Science Foundation of China(52106193,21908162)+2 种基金the Natural Science Foundation of Hunan Province(2021JJ40756)the Science and Technology Innovation Program of Hunan Province(2020GK2070)the Innovation-Driven Project of Central South University(2020CX008)
文摘Hydrogen is an indispensable energy carrier for the sustainable development of human society.Nevertheless,its storage,transportation,and in situ generation still face significant challenges.Methanol can be used as an intermediate carrier for hydrogen supplies,providing hydrogen energy through instant methanol conversion.In this study,a sorption-enhanced,chemical-looping,oxidative steam methanol-reforming(SECLOSRM)process is proposed using CuO–MgO for the on-board hydrogen supply,which could be a promising method for safe and efficient hydrogen production.Aspen Plus software was used for feasibility verification and parameter optimization of the SECL-OSRM process.The effects of CuO/CH_(3)OH,MgO/CH_(3)OH,and H_(2)O/CH_(3)OH mole ratios and of temperature on H_(2)production rate,H utilization efficiency,CH_(3)OH conversion,CO concentration,and system heat balance are discussed thoroughly.The results indicate that the system can be operated in autothermal conditions with high-purity hydrogen(99.50 vol%)and ultra-low-concentration CO(<50 ppm)generation,which confirms the possibility of integrating low-temperature proton-exchange membrane fuel cells(LT-PEFMCs)with the SECL-OSRM process.The simulation results indicate that the CO can be modulated in a lower concentration by reducing the temperature and by improving the H_(2)O/CH_(3)OH and MgO/CH_(3)OH mole ratios.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51071046,61078030,11074046,11174056,11274113the National Basic Research Program of China(2009CB929201)the Characterization Facility,University of Minnesota,a member of the NSF-funded Materials Research Facilities Network(www.mrfn.org)via the NSF MRSEC program under award number DMR-0819885.
文摘The influence of surface/interface roughness on the magnetic properties of Fe/Ni multilayers is investigated.Two methods are employed to tune the film roughness:one varies the substrate temperature,and the other pre-deposits a Ag underlayer on the MgO substrate.For films with higher roughness,a marked rise in coercivity is observed.Three factors are discussed to be mainly responsible for the coercivity rise,involving the formation of pinholes,the reduction of exchange coupling between Fe and Ni layers,and Fe-Ni alloying at interfaces.
基金This study was partially supported by the Industrial Innovation Center(IIC),Atyab Food Tech LLC and Sultan Qaboos University–College of Agricultural and Marine Sciences Dean’s Seed Grant.
基金This material is based upon work supported by the U.S.Department of Energy,Office of Science,Office of Advanced Scientific Computing Research,Scientific Discovery through Advanced Computing(SciDAC)program,under Award No.DE-SC0008666.
文摘Dye-sensitized solar cells(DSSCs) are one of the most promising renewable energy technologies. Charge transfer and charge transport are pivotal processes in DSSCs, which govern solar energy capture and conversion. These processes can be probed using modern electronic structure methods. Because of the heterogeneity and complexity of the local environment of a chromophore in DSSCs(such as solvatochromism and chromophore aggregation), a part of the solvation environment should be treated explicitly during the calculation. However, because of the high computational cost and unfavorable scaling with the number of electrons of high-level quantum mechanical methods, approaches to explicitly treat the local environment need careful consideration. Two problems must be tackled to reduce computational cost. First, the number of configurations representing the solvent distribution should be limited as much as possible. Second, the size of the explicit region should be kept relatively small. The purpose of this study is to develop efficient computational approaches to select representative configurations and to limit the explicit solvent region to reduce the computational cost for later(higher-level) quantum mechanical calculations. For this purpose, an ensemble of solvent configurations around a 1-methyl-8-oxyquinolinium betaine(QB) dye molecule was generated using Monte Carlo simulations and molecular mechanics force fields. Then, a fitness function was developed using data from inexpensive electronic structure calculations to reduce the number of configurations. Specific solvent molecules were also selected for explicit treatment based on a distance criterion, and those not selected were treated as background charges. The configurations and solvent molecules selected proved to be good representatives of the entire ensemble; thus, expensive electronic structure calculations need to be performed only on this subset of the system, which significantly reduces the computational cost.
基金supported by an NSF CAREER Award(CMMI-1454293)a Grant-In-Aid(GIA)program/a start-up fund at the University of Minnesota,Twin Cities+2 种基金Parts of this work were carried out in the Characterization Facility,University of Minnesota,a member of the NSF-funded Materials Research Facilities Network(www.mrfn.org)via the MRSEC programA portion of this work was also carried out in the Minnesota Nano Center which receives partial support from the NSF through the NNCI programthe 3M Science and Technology Fellowship
文摘Grain coalescence has been applied in many areas of nanofabrication technology, including modification of thinfilm properties, nanowelding, and self-assembly of nanostructures. However, very few systematic studies of selfassembly using the grain coalescence, especially for threedimensional(3D) nanostructures, exist at present. Here, we investigate the mechanism of plasma triggered grain coalescence to achieve the precise control of nanoscale phase and morphology of the grain coalescence induced by exothermic energy. Exothermic energy is generated through etching a silicon substrate via application of plasma. By tuning the plasma power and the flow rates of reactive gases, different etching rates and profiles can be achieved, resulting in various morphologies of grain coalescence. Balancing the isotropic/anisotropic substrate etching profile and the etching rate makes it possible to simultaneously release 2D nanostructures from the substrate and induce enough surface tension force,generated by grain coalescence, to form 3D nanostructures.Diverse morphologies of 3D nanostructures have been obtained by the grain coalescence, and a strategy to achieve self-assembly, resulting in desired 3D nanostructures, has been proposed and demonstrated.
文摘Substrate-free films of N-4-n-butoxybenzylidene-4-n-octylaniline(40.8)show a fascinating interlayer interaction.This interaction significantly affects the next ordering transition,or the second hexatic-B order,upon cooling.The Landau-de Gennes theory is employed to model the effect of the enhanced order by surface-ordering field.Based on this model,it is found that the surface-order penetration depth to be less than one layer.
文摘Traffic data collection is essential for performance assessment, safety improvement and road planning. While automated traffic data collection for highways is relatively mature, that for roundabouts is more challenging due to more complex traffic scenes, data specifications and vehicle behavior. In this paper, the authors propose an automated traffic data collection system dedicated to roundabout scenes. The proposed system has mainly four steps of processing. First, camera calibration is performed for roundabout traffic scenes with a novel circle-based calibration algorithm. Second, the system uses enhanced Mixture of Gaussian algorithm with shaking removal for video segmentation, which can tolerate repeated camera displacements and background movements. Then, Kalman filtering, Kemel-based tracking and overlap-based opti- mization are employed to track vehicles while they are occluded and to derive the complete vehicle trajectories. The resulting vehicle trajectory of each individual vehicle gives the position, size, shape and speed of the vehicle at each time moment. Finally, a data mining algorithm is used to automatically extract the interested traffic data from the vehicle trajectories. The overall traffic data collection system has been implemented in software and runs on regular PC. The total processing time for a 3-hour video is currently 6 h. The automated traffic data collection system can significantly reduce cost and improve efficiency compared to manual data collection. The extracted traffic data have been compared to accurate manual measurements for 29 videos recorded on 29 different days, and an accuracy of more than 90% has been achieved.
文摘Smart cities depend highly on an intelligent electrical networks to provide a reliable,safe,and clean power supplies.A smart grid achieves such aforementioned power supply by ensuring resilient energy delivery,which presents opportunities to improve the cost-effectiveness of power supply and minimize environmental impacts.A systematic evaluation of the comprehensive benefits brought by smart grid to smart cities can provide necessary theoretical fundamentals for urban planning and construction towards a sustainable energy future.However,most of the present methods of assessing smart cities do not fully take into account the benefits expected from the smart grid.To comprehensively evaluate the development levels of smart cities while revealing the supporting roles of smart grids,this article proposes a model of smart city development needs from the perspective of residents’needs based on Maslow’s Hierarchy of Needs theory,which serves the primary purpose of building a smart city.By classifying and reintegrating the needs,an evaluation index system of smart grids supporting smart cities was further constructed.A case analysis concluded that smart grids,as an essential foundation and objective requirement for smart cities,are important in promoting scientific urban management,intelligent infrastructure,refined public services,efficient energy utilization,and industrial development and modernization.Further optimization suggestions were given to the city analyzed in the case include strengthening urban management and infrastructure constructions,such as electric vehicle charging facilities and wireless coverage.
文摘A new approach to threshold resonance calculation by the complex scaling method is discussed.Application to scattering over a model potential barrier is presented and compared to a direct quantum scattering calculation.
基金the financial support from the National Natural Science Foundation of China (No. 21766019, 21466022)the Key Research and Development Program of Jiangxi Province(20171BBF60023)+2 种基金the International Science&Technology Cooperation Project of China(2015DFA60170-4)the Science and Technology Research Project of Jiangxi Province Education Department(No.GJJ150213)the Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Program (No. Y707sb1001)”
文摘The method for pyrolysis of biomass to manufacture hydrocarbon-rich fuel remains challenging in terms of conversion of multifunctional biomass with high oxygen content and low thermal stability into a high-quality compound, featuring high content of hydrocarbons, low oxygen content, few functional groups, and high thermal stability. This study offers a promising prospect to derive hydrocarbon-rich oil through microwave-assisted fast catalytic pyrolysis by improving the effective hydrogen to carbon ratio(H/Ceff) of the raw materials. The proposed technique can promote the production of high-quality bio-oil through the molecular sieve catalyzed reduction of oxygenated compounds and mutagenic polyaromatic hydrocarbons. This work aims to review and summarize the research progress on microwave copyrolysis and microwave catalytic copyrolysis to demonstrate their benefits on enhancement of bio-oils derived from the biomass. This review focuses on the potential of optimizing the H/Ceff ratio, the microwave absorbent, and the HZSM-5 catalyst during the microwave copyrolysis to produce the valuable liquid fuel. This paper also proposes future directions for the use of this technique to obtain high yields of bio-oils.
