A systematic study has been conducted on microcavity organic light emitting diodes(OLEDs)based on green,red and blue phosphorescent emitters to elucidate the microcavity effects for different color emitters.We found t...A systematic study has been conducted on microcavity organic light emitting diodes(OLEDs)based on green,red and blue phosphorescent emitters to elucidate the microcavity effects for different color emitters.We found that the luminance output is determined by the reflectivity of the semitransparent electrode and the photopic response of the green,red and blue emitters.While the luminance enhancements of blue and red phosphorescent microcavity devices are small,a current efficiency as high as 224 cd A21 is obtained in the green phosphorescent microcavity OLEDs.展开更多
Background:"Chickenpox"is a highly infectious disease caused by the varicella-zoster virus,influenced by seasonal and spatial factors.Dealing with varicella-zoster epidemics can be a substantial drain on hea...Background:"Chickenpox"is a highly infectious disease caused by the varicella-zoster virus,influenced by seasonal and spatial factors.Dealing with varicella-zoster epidemics can be a substantial drain on health-authority resources.Methods that improve the ability to locally predict case numbers from time-series data sets every week are therefore worth developing.Methods:Simple-to-extract trend attributes from published univariate weekly case-number univariate data sets were used to generate multivariate data for Hungary covering 10 years.That attribute-enhanced data set was assessed by machine learning(ML)and deep learning(DL)models to generate weekly case forecasts from next week(t0)to 12 weeks forward(t+12).The ML and DL predictions were compared with those generated by multilinear regression and univariate prediction methods.Results:Support vector regression generates the best predictions for weeks t0 and t+1,whereas extreme gradient boosting generates the best predictions for weeks t+3 to t+12.Long-short-term memory only provides comparable prediction accuracy to the ML models for week t+12.Multi-K-fold cross validation reveals that overall the lowest prediction uncertainty is associated with the tree-ensemble ML models.Conclusion:The novel trend-attribute method offers the potential to reduce prediction errors and improve transparency for chickenpox timeseries.展开更多
For the first time, Mo nanoscrew was cultivated as a novel non-coinage-metal substrate for surface-enhanced Raman scattering(SERS). It was found that the nanoscrew is composed of many small screw threads stacking alon...For the first time, Mo nanoscrew was cultivated as a novel non-coinage-metal substrate for surface-enhanced Raman scattering(SERS). It was found that the nanoscrew is composed of many small screw threads stacking along its length direction with small separations. Under external light excitation, strong electromagnetic coupling was initiated within the gaps, and many hot-spots formed on the surface of the nanoscrew, which was confirmed by high-resolution scanning near-field optical microscope measurements and numerical simulations using finite element method. These hotspots are responsible for the observed SERS activity of the nanoscrews. Raman mapping characterizations further revealed the excellent reproducibility of the SERS activity. Our findings may pave the way for design of low-cost and stable SERS substrates.展开更多
The development of capsule endoscopy(CE) in 2001 has given gastroenterologists the opportunity to investigate the small bowel in a non-invasive way. CE is most commonly performed for obscure gastrointestinal bleeding,...The development of capsule endoscopy(CE) in 2001 has given gastroenterologists the opportunity to investigate the small bowel in a non-invasive way. CE is most commonly performed for obscure gastrointestinal bleeding, but other indications include diagnosis or follow-up of Crohn's disease, suspicion of a small bowel tumor, diagnosis and surveillance of hereditary polyposis syndromes, Nonsteroidal anti-inflammatory drug-induced small bowel lesions and celiac disease.Almost fifteen years have passed since the release of the small bowel capsule. The purpose of this review is to offer the reader a brief but complete overview on small bowel CE anno 2014, including the technical and procedural aspects, the possible complications and the most important indications. We will end with some future perspectives of CE.展开更多
The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level stat...The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.展开更多
An extreme solar cosmic ray event broke out on 2005 January 20. Not only is it the most intensive solar energetic particle （SEP） event, with 〉100 MeV particles measured by GOES satellite since 1986, but it has been...An extreme solar cosmic ray event broke out on 2005 January 20. Not only is it the most intensive solar energetic particle （SEP） event, with 〉100 MeV particles measured by GOES satellite since 1986, but it has been the largest ground level enhancement （GLE） event recorded by the ground-based neutron monitors since 1956. This work presents the solar proton spectra for this event with data obtained by GOES in multiple energy channels. These spectra are well fitted by a modified power-law function. The spectral index of around -1 indicates that the January 20 event has a hard energy spectrum. Possible mechanisms for the acceleration of relativistic protons are discussed.展开更多
Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N...Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N, 127.8°E, Geomagnetic 15.3°N）, Yamagawa （31.2°N, 130.6°E, Geomagnetic 20.4°N）, Kokubunji （35.7°N, 139.5°E, Geomagnetic 25.5°N）, and Wakkanai （45.4°N, 141.7°E, Geomagnetic 35.4°N） in East Asia during several solar cycles. The results show that there are obvious seasonal and solar activity dependencies of the nighttime electron density enhancements. The enhancements are termed pre-midnight enhancement and post-midnight enhancement, according to the local time when the enhancement appeared. The former has a higher occurrence probability in summer months than in winter months. In contrast, the latter has a larger occurrence probability in winter months than in summer months. Moreover, the nighttime enhancements in electron density are more likely to occur at lower solar activity. These seasonal and solar activity variations of the nighttime enhancements in electron density can be explained in terms of the combined effects of downward plasma flux from the plasmasphere and the neutral winds.展开更多
This research is a study assessing the performance of hybrid nanofluids in hybrid photovoltaic(PV)-thermal systems.This study addresses 10 hybrid nanofluids applied to hybrid PV-thermal systems.The transition to carbo...This research is a study assessing the performance of hybrid nanofluids in hybrid photovoltaic(PV)-thermal systems.This study addresses 10 hybrid nanofluids applied to hybrid PV-thermal systems.The transition to carbon-free energy can mitigate the worst effects of climate change,ensuring that global sustainability is addressed.Clean energy is now responsible for one-third of the global capacity,of which 20%is attributed to solar energy.Renewables continue to be economically viable,with declining costs driving growth.This study aims to compare the yearly performances of a model hybrid PV-thermal system using 10 different hybrid nanofluids.Hybrid nanofluids constitute two or more dissimilar materials stably suspended in a base fluid(e.g.water).MATLAB and COMSOL Multiphysics®computational fluid dynamics software are employed together for the benchmarking assessment with good agreement observed.Various fluid inlet temperatures(Tin∈[300,360]K),nanofluid volume concentrations(φ∈[0,4]%)and storage-tank volumes(V∈[50,300]L)were simulated.The meteorological data applied were those for Lagos,Nigeria(6°27’55.5192”N,3°24’23.2128”E).The assessment based on analytical-numerical solutions reveals that the thermal enhancement by hybrid nanofluids ranges from 6.7%(graphene oxide[GO]-multiwalled carbon nanotube[MWCNT]/water)to 7%(ZnO-Mn-ZnFe2O4/water)forφ=2%and V=300 L.The yearly exergy efficiency ranges from 2.8%(ZnO-Mn-ZnFe2O4/water)to 2.9%(GO-MWCNT/water),also forφ=2%and V=300 L.These findings have implications for a vast range of industrial processes,expanding the knowledge that is critical to a sustainable future.展开更多
Software is in constant evolution and many approaches have been suggested to study software maintenance productivity. This research reports on a process to design and implement a productivity model of legacy software ...Software is in constant evolution and many approaches have been suggested to study software maintenance productivity. This research reports on a process to design and implement a productivity model of legacy software based on the measurement of small functional enhancements using the COSMIC ISO 19761 international standard. Two motivations influence this research: 1) understanding the productivity of the software maintenance process to help manage the cost of maintenance;2) understanding the cost drivers that affect the software maintenance productivity. This research reports on an empirical study of a productivity measurement program implemented in a large banking legacy system.展开更多
文摘A systematic study has been conducted on microcavity organic light emitting diodes(OLEDs)based on green,red and blue phosphorescent emitters to elucidate the microcavity effects for different color emitters.We found that the luminance output is determined by the reflectivity of the semitransparent electrode and the photopic response of the green,red and blue emitters.While the luminance enhancements of blue and red phosphorescent microcavity devices are small,a current efficiency as high as 224 cd A21 is obtained in the green phosphorescent microcavity OLEDs.
文摘Background:"Chickenpox"is a highly infectious disease caused by the varicella-zoster virus,influenced by seasonal and spatial factors.Dealing with varicella-zoster epidemics can be a substantial drain on health-authority resources.Methods that improve the ability to locally predict case numbers from time-series data sets every week are therefore worth developing.Methods:Simple-to-extract trend attributes from published univariate weekly case-number univariate data sets were used to generate multivariate data for Hungary covering 10 years.That attribute-enhanced data set was assessed by machine learning(ML)and deep learning(DL)models to generate weekly case forecasts from next week(t0)to 12 weeks forward(t+12).The ML and DL predictions were compared with those generated by multilinear regression and univariate prediction methods.Results:Support vector regression generates the best predictions for weeks t0 and t+1,whereas extreme gradient boosting generates the best predictions for weeks t+3 to t+12.Long-short-term memory only provides comparable prediction accuracy to the ML models for week t+12.Multi-K-fold cross validation reveals that overall the lowest prediction uncertainty is associated with the tree-ensemble ML models.Conclusion:The novel trend-attribute method offers the potential to reduce prediction errors and improve transparency for chickenpox timeseries.
基金supported by the National Natural Science Foundation of China(Grant Nos.11474364,51202300,51290271)the National Key Basic Research Program of China(Grant Nos.2013CB933601,2013YQ12034506)+3 种基金the Guangdong Natural Science Funds for Distinguished Young Scholar(Grant No.2014A030306017)the Guangdong Special Support Program,the Doctoral Fund of Ministry of Education of China(Grant No.20120171120012)the Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT13042)the Fundamental Research Funds for the Central Universities
文摘For the first time, Mo nanoscrew was cultivated as a novel non-coinage-metal substrate for surface-enhanced Raman scattering(SERS). It was found that the nanoscrew is composed of many small screw threads stacking along its length direction with small separations. Under external light excitation, strong electromagnetic coupling was initiated within the gaps, and many hot-spots formed on the surface of the nanoscrew, which was confirmed by high-resolution scanning near-field optical microscope measurements and numerical simulations using finite element method. These hotspots are responsible for the observed SERS activity of the nanoscrews. Raman mapping characterizations further revealed the excellent reproducibility of the SERS activity. Our findings may pave the way for design of low-cost and stable SERS substrates.
文摘The development of capsule endoscopy(CE) in 2001 has given gastroenterologists the opportunity to investigate the small bowel in a non-invasive way. CE is most commonly performed for obscure gastrointestinal bleeding, but other indications include diagnosis or follow-up of Crohn's disease, suspicion of a small bowel tumor, diagnosis and surveillance of hereditary polyposis syndromes, Nonsteroidal anti-inflammatory drug-induced small bowel lesions and celiac disease.Almost fifteen years have passed since the release of the small bowel capsule. The purpose of this review is to offer the reader a brief but complete overview on small bowel CE anno 2014, including the technical and procedural aspects, the possible complications and the most important indications. We will end with some future perspectives of CE.
基金supported by the National Natural Science Foundation of China(NNSF)(Grant Nos.10147207 and 10375001)China Shanghai Foundation for Developing Science and Technology(Grant No.0252nm082)+1 种基金China Shanghai Foundation for Developing Science and Technology in Universities(Grant No.03DZ03)the Third Phase Foundation of Theoretical Center in China Lanzhou National Key Laboratory.
文摘The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.
文摘An extreme solar cosmic ray event broke out on 2005 January 20. Not only is it the most intensive solar energetic particle （SEP） event, with 〉100 MeV particles measured by GOES satellite since 1986, but it has been the largest ground level enhancement （GLE） event recorded by the ground-based neutron monitors since 1956. This work presents the solar proton spectra for this event with data obtained by GOES in multiple energy channels. These spectra are well fitted by a modified power-law function. The spectral index of around -1 indicates that the January 20 event has a hard energy spectrum. Possible mechanisms for the acceleration of relativistic protons are discussed.
基金supported by the projects of Chinese Academy of Sciences(Grant No.KZZD-EW-01-3)the National Basic Research Program of China(Grant No.2012CB825604)the National Natural Science Foundation of China(Grant Nos.41231065,41174137,41321003)
文摘Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N, 127.8°E, Geomagnetic 15.3°N）, Yamagawa （31.2°N, 130.6°E, Geomagnetic 20.4°N）, Kokubunji （35.7°N, 139.5°E, Geomagnetic 25.5°N）, and Wakkanai （45.4°N, 141.7°E, Geomagnetic 35.4°N） in East Asia during several solar cycles. The results show that there are obvious seasonal and solar activity dependencies of the nighttime electron density enhancements. The enhancements are termed pre-midnight enhancement and post-midnight enhancement, according to the local time when the enhancement appeared. The former has a higher occurrence probability in summer months than in winter months. In contrast, the latter has a larger occurrence probability in winter months than in summer months. Moreover, the nighttime enhancements in electron density are more likely to occur at lower solar activity. These seasonal and solar activity variations of the nighttime enhancements in electron density can be explained in terms of the combined effects of downward plasma flux from the plasmasphere and the neutral winds.
文摘This research is a study assessing the performance of hybrid nanofluids in hybrid photovoltaic(PV)-thermal systems.This study addresses 10 hybrid nanofluids applied to hybrid PV-thermal systems.The transition to carbon-free energy can mitigate the worst effects of climate change,ensuring that global sustainability is addressed.Clean energy is now responsible for one-third of the global capacity,of which 20%is attributed to solar energy.Renewables continue to be economically viable,with declining costs driving growth.This study aims to compare the yearly performances of a model hybrid PV-thermal system using 10 different hybrid nanofluids.Hybrid nanofluids constitute two or more dissimilar materials stably suspended in a base fluid(e.g.water).MATLAB and COMSOL Multiphysics®computational fluid dynamics software are employed together for the benchmarking assessment with good agreement observed.Various fluid inlet temperatures(Tin∈[300,360]K),nanofluid volume concentrations(φ∈[0,4]%)and storage-tank volumes(V∈[50,300]L)were simulated.The meteorological data applied were those for Lagos,Nigeria(6°27’55.5192”N,3°24’23.2128”E).The assessment based on analytical-numerical solutions reveals that the thermal enhancement by hybrid nanofluids ranges from 6.7%(graphene oxide[GO]-multiwalled carbon nanotube[MWCNT]/water)to 7%(ZnO-Mn-ZnFe2O4/water)forφ=2%and V=300 L.The yearly exergy efficiency ranges from 2.8%(ZnO-Mn-ZnFe2O4/water)to 2.9%(GO-MWCNT/water),also forφ=2%and V=300 L.These findings have implications for a vast range of industrial processes,expanding the knowledge that is critical to a sustainable future.
文摘Software is in constant evolution and many approaches have been suggested to study software maintenance productivity. This research reports on a process to design and implement a productivity model of legacy software based on the measurement of small functional enhancements using the COSMIC ISO 19761 international standard. Two motivations influence this research: 1) understanding the productivity of the software maintenance process to help manage the cost of maintenance;2) understanding the cost drivers that affect the software maintenance productivity. This research reports on an empirical study of a productivity measurement program implemented in a large banking legacy system.
