Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this s...Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined.The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e.,an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.展开更多
In this paper,we describe a novel and simple process for the fabrication of all-transparent and encapsulated polymeric nanofluidic devices using nano-indentation lithography.First,a nanomechanical probe is used to‘sc...In this paper,we describe a novel and simple process for the fabrication of all-transparent and encapsulated polymeric nanofluidic devices using nano-indentation lithography.First,a nanomechanical probe is used to‘scratch’nanoscale channels on polymethylmethacrylate(PMMA)substrates with sufficiently high hardness.Next,polydimethylsiloxane(PDMS)is used twice to duplicate the nanochannels onto PDMS substrates from the‘nano-scratched’PMMA substrates.A number of experiments are conducted to explore the relationships between the nano-indentation parameters and the nanochannel dimensions and to control the aspect ratio of the fabricated nanochannels.In addition,traditional photolithography combined with soft lithography is employed to fabricate microchannels on another PDMS‘cap’substrate.After manually aligning the substrates,all uncovered channels on two separate PDMS substrates are bonded to achieve a sealed and transparent nanofluidic device,which makes the dimensional transition from microscale to nanoscale feasible.The smallest dimensions of the achievable nanochannels that we have demonstrated thus far are of~20 nm depth and~800 nm width,with lengths extendable beyond 100μm.Fluid flow experiments are performed to verify the reliability of the device.Two types of colloidal solution are used to visualize the fluid flow through the nanochannels,that is,ethanol is mixed with gold colloid or fluorescent dye(fluorescein isothiocyanate),and the flow rate and filling time of liquid in the nanochannels are estimated based on time-lapsed image data.The simplicity of the fabrication process,bio-compatibility of the polymer substrates,and optical transparency of the nanochannels for flow visualization are key characteristics of this approach that will be very useful for nanofluidic and biomolecular research applications in the future.展开更多
It is known that the leading edge has the most critical heat transfer area of a gas turbine blade.The highest heat transfer rates on the airfoil can always be found on the stagnation region of the leading edge.In orde...It is known that the leading edge has the most critical heat transfer area of a gas turbine blade.The highest heat transfer rates on the airfoil can always be found on the stagnation region of the leading edge.In order to further improve the gas turbine thermal efficiency the development of more advanced internal cooling configurations at leading edge is very necessary.As the state of the art leading edge cooling configuration a concave channel with multi inline jets has been widely used in most of the blades.However,this kind of configuration also generates strong spent flow,which shifts the impingement off the stagnation point and weakens the impingement heat transfer.In order to solve this problem a new internal cooling configuration using double swirl chambers in gas turbine leading edge has been developed and introduced in this paper.The double swirl chambers cooling(DSC)technology is introduced by the authors and contributes a significant enhancement of heat transfer due to the generation of two anti-rotated swirls.In DSC-cooling,the reattachment of the swirl flows always occurs in the middle of the chamber,which results in a linear impingement effect.Compared with the reference standard impingement cooling configuration this new cooling system provides a much more uniform heat transfer distribution in the chamber axial direction and also provides a much higher heat transfer rate.In this study,the influences of different geometrical parameters e.g.merging ratio of two cylinder channels,the jet inlet hole configurations and radius of blunt protuberances in DSC have been investigated numerically.The results show that in the DSC cooling system the jet inlet hole configurations have large influences on the thermal performance.The rectangular inlet holes,especially those with higher aspect ratios,show much better heat transfer enhancement than the round inlet holes.However,as the price for it the total pressure drop is increased.Using blunt protuberances instead of sharp edges in the DSC cooling can improve the 展开更多
A series of hydraulic model tests with horizontal movable seabed under regular wave actions have been carried out to investigate the dynamic interactions between water waves and seabed soil. Seabed dynamic stresses fr...A series of hydraulic model tests with horizontal movable seabed under regular wave actions have been carried out to investigate the dynamic interactions between water waves and seabed soil. Seabed dynamic stresses from experiments are, tound to differ from theoretical resuhs. The response of p0 in permeable seabed has a small decay and phase shift to the nonlinear wave actions, and the dynamic stresses, σs/p0, σh/p0 and u/p0, contain different phase shift characteristics. Such phenomena will strongly affect the dynamic stress path in seabed. If the phase shifts of σs. and σh are neglected, the stress path will become a straight line; otherwise, it will become an elliptical curve. In phase shift cases, the long axis of the p - q diagram will be shortened when the depth increases, and the short axis will become longer when the phase shift increases. For the p＇ - q＇ diagram, the larger the phase lag of u, the longer the short axis. Relative results offer useful information for the analysis of seabed stability.展开更多
Purpose–The purpose of this paper is to propose an integrated fuzzy approach to determine important universal usability problems(UUPs)by providing experts who behave like real users and to establish a work plan to co...Purpose–The purpose of this paper is to propose an integrated fuzzy approach to determine important universal usability problems(UUPs)by providing experts who behave like real users and to establish a work plan to correct the most important ones.Design/methodology/approach–In this study,a fuzzy multi-criteria decision-making approach with three stages is proposed for the evaluation of universal usability.At the first stage,UUPs are identified by performing modified heuristic evaluation,and severity rating of each problem is determined by experts.At the second stage,critical problems are specified by applying the fuzzy Delphi considering these severity ratings.At the third stage,Fuzzy Decision Making Trial and Evaluation Laboratory approach is applied to prioritize critical problems as sub and main criteria.An illustrative example related to emergency service is performed to apply the proposed approach.Findings–Results showed that the elevator button design,the elevator emergency button design and the position of the floor signboard are the first three problems that should be primarily improved as sub-criteria.In terms of maincriteria,equitableuse,simpleand intuitiveuse,andperceptible informationare the first three main criteria that should be improve in emergency service.Originality/value–This study is original in terms of methodology and providing a new perspective for building design evaluation.The results can help the designers to see the UUPs in buildings,to focus the most important UUPs and to establish improvement ranking.These advantages provide time and cost-effective design improvement actions.展开更多
This paper develops a deep learning tool based on neural processes(NPs)called the Peri-Net-Pro,to predict the crack patterns in a moving disk and classifies them according to the classification modes with quantified u...This paper develops a deep learning tool based on neural processes(NPs)called the Peri-Net-Pro,to predict the crack patterns in a moving disk and classifies them according to the classification modes with quantified uncertainties.In particular,image classification and regression studies are conducted by means of convolutional neural networks(CNNs)and NPs.First,the amount and quality of the data are enhanced by using peridynamics to theoretically compensate for the problems of the finite element method(FEM)in generating crack pattern images.Second,case studies are conducted with the prototype microelastic brittle(PMB),linear peridynamic solid(LPS),and viscoelastic solid(VES)models obtained by using the peridynamic theory.The case studies are performed to classify the images by using CNNs and determine the suitability of the PMB,LBS,and VES models.Finally,a regression analysis is performed on the crack pattern images with NPs to predict the crack patterns.The regression analysis results confirm that the variance decreases when the number of epochs increases by using the NPs.The training results gradually improve,and the variance ranges decrease to less than 0.035.The main finding of this study is that the NPs enable accurate predictions,even with missing or insufficient training data.The results demonstrate that if the context points are set to the 10th,100th,300th,and 784th,the training information is deliberately omitted for the context points of the 10th,100th,and 300th,and the predictions are different when the context points are significantly lower.However,the comparison of the results of the 100th and 784th context points shows that the predicted results are similar because of the Gaussian processes in the NPs.Therefore,if the NPs are employed for training,the missing information of the training data can be supplemented to predict the results.展开更多
AIM： To examine the anti-ulcerogenic and antioxidant effects of aqueous extracts of Foeniculum vu/gare （FVE） on ethanol-induced gastric lesions in rats.METHODS： FVE was administered by gavage at doses of 75, i50 a...AIM： To examine the anti-ulcerogenic and antioxidant effects of aqueous extracts of Foeniculum vu/gare （FVE） on ethanol-induced gastric lesions in rats.METHODS： FVE was administered by gavage at doses of 75, i50 and 300 mg/kg, and famotidine was used at the dose of20mg/kg.Following a 60 min period, all the rats were given 1 mL of ethanol （80%） by gavage. One hour after the administration of ethanol, all groups were sacrificed, and the gastric ulcer index was calculated; whole blood malondialdehyde （MDA） and reduced glutathione （GSH）, serum nitrate, nitrite, ascorbic acid, retinol and β-carotene levels were measured in all the groups.RESULTS： It was found that pretreatment with FVE significantly reduced ethanol-induced gastric damage. This effect of FVE was highest and statistically significant in 300 mg/kg group compared with the control （4.18 ± 2.81 vs 13.15 ± 4.08, P 〈 0.001）. Also, pretreatment with FVE significantly reduced the MDA levels, while significantly increased GSH, nitrite, nitrate, ascorbic acid, retinol and β-carotene levels. CONCLUSION： FVE has clearly a protective effect against ethanol-induced gastric mucosal lesion, and this effect, at least in part, depends upon the reduction in lipid peroxidation and augmentation in the antioxidant activity.展开更多
DEAR EDITOR,Parents may adjust their breeding time to optimize reproductive output and reduce reproductive costs associated with unpredictable climatic conditions,especially in the context of global warming.The breedi...DEAR EDITOR,Parents may adjust their breeding time to optimize reproductive output and reduce reproductive costs associated with unpredictable climatic conditions,especially in the context of global warming.The breeding performance of tropical bird species in response to local climate change is relatively understudied compared with that of temperate bird species.展开更多
Purpose-The purpose of this paper is to develop an approach to compare occupational health and safety(OHS)performances of countries.Additionally,another aim is to debate the impacts of using recorded data and ratios f...Purpose-The purpose of this paper is to develop an approach to compare occupational health and safety(OHS)performances of countries.Additionally,another aim is to debate the impacts of using recorded data and ratios for OHS performance evaluations.Design/methodology/approach-The number of fatal accidents(NFAs),fatal accident rates(FARs),numbers of lost days(NLDs)and accident severity rates(ASRs)are determined as main criteria and six economic activity areas(EAAs)are considered as sub-criteria.Two different initial decision matrices are used as the initial decision matrix,the first of which consists of recorded data of countries related to NFAs and NLDs,and the second consists of FAR and ASR values as ratios.Importance weights of main and sub-criteria regarding the recorded data and ratios are determined using four different weighting ways.Countries are ranked via utilizing Multi-Attributive Ideal-Real Comparative Analysis considering two different initial decision matrices.Findings-It can be stated that an evaluation based on ratios for comparison of OHS performance provides more realistic results.Additionally,increasing the effect of the FAR values using the 6,000 equivalent lost days factor is also important in terms of differentiating the data of the countries in question.Originality/value-To the best of the authors’knowledge,there is no study in literature that discusses the ranking of countries by means of recorded data and ratios considering different criteria.Additionally,this study is a first in terms of the number of countries evaluated and the comparison of these countries according to their respective EAAs.展开更多
The establishment of a possible connection between neutrino emission and gravitational-wave(GW)bursts is important to our understanding of the physical processes that occur when black holes or neutron stars merge.In t...The establishment of a possible connection between neutrino emission and gravitational-wave(GW)bursts is important to our understanding of the physical processes that occur when black holes or neutron stars merge.In the Daya Bay experiment,using the data collected from December 2011 to August 2017,a search was per-formed for electron-antineutrino signals that coincided with detected GW events,including GW150914,GW151012,GW151226,GW170104,GW170608,GW 170814,and GW 170817.We used three time windows of±10,±500,and±1000 s relative to the occurrence of the GW events and a neutrino energy range of 1.8 to 100 MeV to search for correlated neutrino candidates.The detected electron-antineutrino candidates were consistent with the expected background rates for all the three time windows.Assuming monochromatic spectra,we found upper limits(90%confidence level)of the electron-antineutrino fluence of(1.13-2.44)×10^(11)cm^(-2)at 5 MeV to 8.0×10^(7)cm^(-2)at 100 MeV for the three time w indows.Under the assumption of a Fermi-Dirac spectrum,the upper limits were found to be(5.4-7.0)×10^(9)cm^(2)for the three time windows.展开更多
The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by ...The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by the Daya Bay experiment,in combination with the fission rates of fissile isotopes in the reactor,is used to extract the positron energy spectra resulting from the fission of specific isotopes.This information can be used to produce a precise,data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Daya Bay.The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method.Consistent results are obtained with other unfolding methods.A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated.Given the reactor fission fractions,the technique can predict the energy spectrum to a 2%precision.In addition,we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.展开更多
基金Project supported by the Department of Science and Technology of Shandong Province (No. 02BS044).
文摘Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined.The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e.,an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.
基金This work was supported by the Hong Kong Research Grants Council(Project No.CityU118513 and N_CityU132/14).
文摘In this paper,we describe a novel and simple process for the fabrication of all-transparent and encapsulated polymeric nanofluidic devices using nano-indentation lithography.First,a nanomechanical probe is used to‘scratch’nanoscale channels on polymethylmethacrylate(PMMA)substrates with sufficiently high hardness.Next,polydimethylsiloxane(PDMS)is used twice to duplicate the nanochannels onto PDMS substrates from the‘nano-scratched’PMMA substrates.A number of experiments are conducted to explore the relationships between the nano-indentation parameters and the nanochannel dimensions and to control the aspect ratio of the fabricated nanochannels.In addition,traditional photolithography combined with soft lithography is employed to fabricate microchannels on another PDMS‘cap’substrate.After manually aligning the substrates,all uncovered channels on two separate PDMS substrates are bonded to achieve a sealed and transparent nanofluidic device,which makes the dimensional transition from microscale to nanoscale feasible.The smallest dimensions of the achievable nanochannels that we have demonstrated thus far are of~20 nm depth and~800 nm width,with lengths extendable beyond 100μm.Fluid flow experiments are performed to verify the reliability of the device.Two types of colloidal solution are used to visualize the fluid flow through the nanochannels,that is,ethanol is mixed with gold colloid or fluorescent dye(fluorescein isothiocyanate),and the flow rate and filling time of liquid in the nanochannels are estimated based on time-lapsed image data.The simplicity of the fabrication process,bio-compatibility of the polymer substrates,and optical transparency of the nanochannels for flow visualization are key characteristics of this approach that will be very useful for nanofluidic and biomolecular research applications in the future.
文摘It is known that the leading edge has the most critical heat transfer area of a gas turbine blade.The highest heat transfer rates on the airfoil can always be found on the stagnation region of the leading edge.In order to further improve the gas turbine thermal efficiency the development of more advanced internal cooling configurations at leading edge is very necessary.As the state of the art leading edge cooling configuration a concave channel with multi inline jets has been widely used in most of the blades.However,this kind of configuration also generates strong spent flow,which shifts the impingement off the stagnation point and weakens the impingement heat transfer.In order to solve this problem a new internal cooling configuration using double swirl chambers in gas turbine leading edge has been developed and introduced in this paper.The double swirl chambers cooling(DSC)technology is introduced by the authors and contributes a significant enhancement of heat transfer due to the generation of two anti-rotated swirls.In DSC-cooling,the reattachment of the swirl flows always occurs in the middle of the chamber,which results in a linear impingement effect.Compared with the reference standard impingement cooling configuration this new cooling system provides a much more uniform heat transfer distribution in the chamber axial direction and also provides a much higher heat transfer rate.In this study,the influences of different geometrical parameters e.g.merging ratio of two cylinder channels,the jet inlet hole configurations and radius of blunt protuberances in DSC have been investigated numerically.The results show that in the DSC cooling system the jet inlet hole configurations have large influences on the thermal performance.The rectangular inlet holes,especially those with higher aspect ratios,show much better heat transfer enhancement than the round inlet holes.However,as the price for it the total pressure drop is increased.Using blunt protuberances instead of sharp edges in the DSC cooling can improve the
基金This research was financially supported by the National Science Council , Taiwan under the project entitled"TheStudy of the Dynamic Behavior of Foundation Soil beneath Nearshore structures under Wave Loading Action (I)"withthe project number of NSC-91-2211-E-019-013
文摘A series of hydraulic model tests with horizontal movable seabed under regular wave actions have been carried out to investigate the dynamic interactions between water waves and seabed soil. Seabed dynamic stresses from experiments are, tound to differ from theoretical resuhs. The response of p0 in permeable seabed has a small decay and phase shift to the nonlinear wave actions, and the dynamic stresses, σs/p0, σh/p0 and u/p0, contain different phase shift characteristics. Such phenomena will strongly affect the dynamic stress path in seabed. If the phase shifts of σs. and σh are neglected, the stress path will become a straight line; otherwise, it will become an elliptical curve. In phase shift cases, the long axis of the p - q diagram will be shortened when the depth increases, and the short axis will become longer when the phase shift increases. For the p＇ - q＇ diagram, the larger the phase lag of u, the longer the short axis. Relative results offer useful information for the analysis of seabed stability.
文摘Purpose–The purpose of this paper is to propose an integrated fuzzy approach to determine important universal usability problems(UUPs)by providing experts who behave like real users and to establish a work plan to correct the most important ones.Design/methodology/approach–In this study,a fuzzy multi-criteria decision-making approach with three stages is proposed for the evaluation of universal usability.At the first stage,UUPs are identified by performing modified heuristic evaluation,and severity rating of each problem is determined by experts.At the second stage,critical problems are specified by applying the fuzzy Delphi considering these severity ratings.At the third stage,Fuzzy Decision Making Trial and Evaluation Laboratory approach is applied to prioritize critical problems as sub and main criteria.An illustrative example related to emergency service is performed to apply the proposed approach.Findings–Results showed that the elevator button design,the elevator emergency button design and the position of the floor signboard are the first three problems that should be primarily improved as sub-criteria.In terms of maincriteria,equitableuse,simpleand intuitiveuse,andperceptible informationare the first three main criteria that should be improve in emergency service.Originality/value–This study is original in terms of methodology and providing a new perspective for building design evaluation.The results can help the designers to see the UUPs in buildings,to focus the most important UUPs and to establish improvement ranking.These advantages provide time and cost-effective design improvement actions.
基金Project supported by the National Science Foundation of U.S.A.(Nos.DMS-1555072,DMS-2053746DMS-2134209)+1 种基金the Brookhaven National Laboratory of U.S.A.(No.382247)U.S.Department of Energy(DOE)Office of Science Advanced Scientific Computing Research Program(Nos.DESC0021142 and DE-SC0023161)。
文摘This paper develops a deep learning tool based on neural processes(NPs)called the Peri-Net-Pro,to predict the crack patterns in a moving disk and classifies them according to the classification modes with quantified uncertainties.In particular,image classification and regression studies are conducted by means of convolutional neural networks(CNNs)and NPs.First,the amount and quality of the data are enhanced by using peridynamics to theoretically compensate for the problems of the finite element method(FEM)in generating crack pattern images.Second,case studies are conducted with the prototype microelastic brittle(PMB),linear peridynamic solid(LPS),and viscoelastic solid(VES)models obtained by using the peridynamic theory.The case studies are performed to classify the images by using CNNs and determine the suitability of the PMB,LBS,and VES models.Finally,a regression analysis is performed on the crack pattern images with NPs to predict the crack patterns.The regression analysis results confirm that the variance decreases when the number of epochs increases by using the NPs.The training results gradually improve,and the variance ranges decrease to less than 0.035.The main finding of this study is that the NPs enable accurate predictions,even with missing or insufficient training data.The results demonstrate that if the context points are set to the 10th,100th,300th,and 784th,the training information is deliberately omitted for the context points of the 10th,100th,and 300th,and the predictions are different when the context points are significantly lower.However,the comparison of the results of the 100th and 784th context points shows that the predicted results are similar because of the Gaussian processes in the NPs.Therefore,if the NPs are employed for training,the missing information of the training data can be supplemented to predict the results.
文摘AIM： To examine the anti-ulcerogenic and antioxidant effects of aqueous extracts of Foeniculum vu/gare （FVE） on ethanol-induced gastric lesions in rats.METHODS： FVE was administered by gavage at doses of 75, i50 and 300 mg/kg, and famotidine was used at the dose of20mg/kg.Following a 60 min period, all the rats were given 1 mL of ethanol （80%） by gavage. One hour after the administration of ethanol, all groups were sacrificed, and the gastric ulcer index was calculated; whole blood malondialdehyde （MDA） and reduced glutathione （GSH）, serum nitrate, nitrite, ascorbic acid, retinol and β-carotene levels were measured in all the groups.RESULTS： It was found that pretreatment with FVE significantly reduced ethanol-induced gastric damage. This effect of FVE was highest and statistically significant in 300 mg/kg group compared with the control （4.18 ± 2.81 vs 13.15 ± 4.08, P 〈 0.001）. Also, pretreatment with FVE significantly reduced the MDA levels, while significantly increased GSH, nitrite, nitrate, ascorbic acid, retinol and β-carotene levels. CONCLUSION： FVE has clearly a protective effect against ethanol-induced gastric mucosal lesion, and this effect, at least in part, depends upon the reduction in lipid peroxidation and augmentation in the antioxidant activity.
基金supported by the Lancang-Mekong Cooperation Special Fund(Biodiversity Monitoring and Network Construction along Lancang-Mekong River Basin project)Biodiversity Investigation,Observation,and Assessment Program(2019-2023)of the Ministry of Ecology and Environment of ChinaCAS 135(2017XTBG-F03)。
文摘DEAR EDITOR,Parents may adjust their breeding time to optimize reproductive output and reduce reproductive costs associated with unpredictable climatic conditions,especially in the context of global warming.The breeding performance of tropical bird species in response to local climate change is relatively understudied compared with that of temperate bird species.
文摘Purpose-The purpose of this paper is to develop an approach to compare occupational health and safety(OHS)performances of countries.Additionally,another aim is to debate the impacts of using recorded data and ratios for OHS performance evaluations.Design/methodology/approach-The number of fatal accidents(NFAs),fatal accident rates(FARs),numbers of lost days(NLDs)and accident severity rates(ASRs)are determined as main criteria and six economic activity areas(EAAs)are considered as sub-criteria.Two different initial decision matrices are used as the initial decision matrix,the first of which consists of recorded data of countries related to NFAs and NLDs,and the second consists of FAR and ASR values as ratios.Importance weights of main and sub-criteria regarding the recorded data and ratios are determined using four different weighting ways.Countries are ranked via utilizing Multi-Attributive Ideal-Real Comparative Analysis considering two different initial decision matrices.Findings-It can be stated that an evaluation based on ratios for comparison of OHS performance provides more realistic results.Additionally,increasing the effect of the FAR values using the 6,000 equivalent lost days factor is also important in terms of differentiating the data of the countries in question.Originality/value-To the best of the authors’knowledge,there is no study in literature that discusses the ranking of countries by means of recorded data and ratios considering different criteria.Additionally,this study is a first in terms of the number of countries evaluated and the comparison of these countries according to their respective EAAs.
基金Daya Bay is supported in part by the Ministry of Science and Technology o f China, the U.S. Department o f Energy, the Chinese Academy of Sciences, the CASCenter for Excellence in Particle Physics, the National Natural Science Foundation of China, the Guangdong provincial government, the Shenzhen municipal government,the China General Nuclear Power Group, Key Laboratory of Particle and Radiation Imaging (Tsinghua University), the Ministry of Education, Key Laboratory ofParticle Physics and Particle Irradiation (Shandong University), the Ministry o f Education, Shanghai Laboratory for Particle Physics and Cosmology, the ResearchGrants Council o f the Hong Kong Special Administrative Region of China, the University Development Fund of the University of Hong Kong, the MOE program forResearch of Excellence at National Taiwan University, National Chiao-Tung University, NSC fund support from Taiwan, the U.S. National Science Foundation, the AlfredP. Sloan Foundation, the Ministry o f Education, Youth, and Sports of the Czech Republic, the Charles University GAUK (284317), the Joint Institute o f NuclearResearch in Dubna, Russia, the National Commission of Scientific and Technological Research of Chile, and the Tsinghua University Initiative Scientific Research Program.
文摘The establishment of a possible connection between neutrino emission and gravitational-wave(GW)bursts is important to our understanding of the physical processes that occur when black holes or neutron stars merge.In the Daya Bay experiment,using the data collected from December 2011 to August 2017,a search was per-formed for electron-antineutrino signals that coincided with detected GW events,including GW150914,GW151012,GW151226,GW170104,GW170608,GW 170814,and GW 170817.We used three time windows of±10,±500,and±1000 s relative to the occurrence of the GW events and a neutrino energy range of 1.8 to 100 MeV to search for correlated neutrino candidates.The detected electron-antineutrino candidates were consistent with the expected background rates for all the three time windows.Assuming monochromatic spectra,we found upper limits(90%confidence level)of the electron-antineutrino fluence of(1.13-2.44)×10^(11)cm^(-2)at 5 MeV to 8.0×10^(7)cm^(-2)at 100 MeV for the three time w indows.Under the assumption of a Fermi-Dirac spectrum,the upper limits were found to be(5.4-7.0)×10^(9)cm^(2)for the three time windows.
基金Supported in part by the Ministry of Science and Technology of Chinathe U.S.Department of Energy,the Chinese Academy of Sciences,the CAS Center for Excellence in Particle Physics,the National Natural Science Foundation of China+3 种基金the Guangdong provincial governmentthe Shenzhen municipal government,the China General Nuclear Power Group,the Research Grants Council of the Hong Kong Special Administrative Region of China,the Ministry of Education in TWthe U.S.National Science Foundation,the Ministry of Education,Youth,and Sports of the Czech Republic,the Charles University Research Centre UNCE,the Joint Institute of Nuclear Research in Dubna,Russiathe National Commission of Scientific and Technological Research of Chile。
文摘The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by the Daya Bay experiment,in combination with the fission rates of fissile isotopes in the reactor,is used to extract the positron energy spectra resulting from the fission of specific isotopes.This information can be used to produce a precise,data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Daya Bay.The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method.Consistent results are obtained with other unfolding methods.A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated.Given the reactor fission fractions,the technique can predict the energy spectrum to a 2%precision.In addition,we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.
