As a powerful tool to diagnose vertical motion, frontogenesis, and secondary circulation, the Q vector and its divergence are widely used. However, little attention has been given to the curl of Q vector. In this pape...As a powerful tool to diagnose vertical motion, frontogenesis, and secondary circulation, the Q vector and its divergence are widely used. However, little attention has been given to the curl of Q vector. In this paper, a new set of analyses combining the divergence of the Q vector (DQ) with the vertical component of the curl of the Q vector (VQ) is applied to a Northeastern cold vortex rainfall case. From the derivation, it was found that the expressions of the Q vectors and their divergences in saturated moist flow (DQm) differ from those of dry and unsaturated moist atmosphere (DQ), while the VQs of various background flows are exactly the same, which largely simplified the analyses. This case study showed that, compared with the DQ, not only can the DQm diagnose precipitation more effectively, but the VQ may also be indicative of precipitation (especially for heavy rainfall and strong convection) because of its direct, close relationship with ageostrophic motion. Thus, the VQ may be computed and analyzed with ease, and may serve as a useful tool for analyses of precipitation and strong convective svstems.展开更多
A precise zoom magnification is important for semiconductor industry and biomedical research. A novel measurement method is demonstrated for optical zoom magnification measurement in this paper. The magnification is o...A precise zoom magnification is important for semiconductor industry and biomedical research. A novel measurement method is demonstrated for optical zoom magnification measurement in this paper. The magnification is obtained by pattern correction between barcode image formed by optical zoom and reference image generated by an ideal optical model. Measurement accuracy which is better than 0.06% has been achieved for optical zoom magnification. Compared with traditional concept, the measurement results are only dependent on two line edges. The barcode correlation method can achieve higher accuracy and better robustness by using the information over the whole field of view.展开更多
Characteristic measurement of contact discharge currents are made through a hand-held metal rod from charged human body. Correlation coefficients are obtained, through Statistic Package for Social Science (SPSS), for ...Characteristic measurement of contact discharge currents are made through a hand-held metal rod from charged human body. Correlation coefficients are obtained, through Statistic Package for Social Science (SPSS), for various charge voltages, which is based on the effect test of electrode contact approach speeds on discharge current parameters of current peaks, maximum rising slope and spark lengths. Discharge parameters at charge voltage 300V are independent on approach speed. For charge voltages equal to and higher than 500V, the contact approach speed has strong positive cor- relation with discharge parameters of the peak current and the maximum rising slope, whereas has strong negative correlation with the spark length.展开更多
The fictitious compress recovery approach is introduced, which could be applied to the establishment of the Rungerarup theorem, the determination of the Bjerhammar's fictitious gravity anomaly, the solution of the "...The fictitious compress recovery approach is introduced, which could be applied to the establishment of the Rungerarup theorem, the determination of the Bjerhammar's fictitious gravity anomaly, the solution of the "downward con- tinuation" problem of the gravity field, the confirmation of the convergence of the spherical harmonic expansion series of the Earth's potential field, and the gravity field determination in three cases: gravitational potential case, gravitation case, and gravitational gradient case. Several tests using simulation experiments show that the fictitious compress recovery approach shows promise in physical geodesy applications.展开更多
AIM:To detect of colorectal cancer(CRC) circulating tumour cells(CTCs) surface antigens,we present an assay incorporating cadmium selenide quantum dots(QDs) in these paper.METHODS:The principle of the assay is the imm...AIM:To detect of colorectal cancer(CRC) circulating tumour cells(CTCs) surface antigens,we present an assay incorporating cadmium selenide quantum dots(QDs) in these paper.METHODS:The principle of the assay is the immunomagnetic separation of CTCs from body fluids in conjunction with QDs,using specific antibody biomarkers:epithelial cell adhesion molecule antibody,and monoclonal cytokeratin 19 antibody.The detection signal was acquired from the fluorescence signal of QDs.For the evaluation of the performance,the method under study was used to isolate the human colon adenocarcinoma cell line(DLD-1) and CTCs from CRC patients' peripheral blood.RESULTS:The minimum detection limit of the assay was defined to 10 DLD-1 CRC cells/mL as fluorescence was measured with a spectrofluorometer.Fluorescenceactivated cell sorting analysis and Real Time RT-PCR,they both have also been used to evaluate the performance of the described method.In conclusion,we developed a simple,sensitive,efficient and of lower cost(than the existing ones) method for the detection of CRC CTCs in human samples.We have accomplished these results by using magnetic bead isolation and subsequent QD fluorescence detection.CONCLUSION:The method described here can be easily adjusted for any other protein target of either the CTC or the host.展开更多
The compact form of the electroweak chiral Lagrangian is a reformulation of its original form and is expressed in terms of chiral rotated electroweak gauge fields, which is crucial for relating the information of unde...The compact form of the electroweak chiral Lagrangian is a reformulation of its original form and is expressed in terms of chiral rotated electroweak gauge fields, which is crucial for relating the information of underlying theories to the coefficients of the low-energy effective Lagrangian. However the compact form obtained in previous works is not complete. In this letter we add several new chiral invariant terms to it and discuss the contributions of these terms to the original electroweak chiral Lagrangian.展开更多
Detachment size determination with an acoustic method has been carried out for two interacting bubble plumes formed at neighboring needles in quiescent water. Two sets of needle pairs, one with 1.5mm and 0.8mm inner d...Detachment size determination with an acoustic method has been carried out for two interacting bubble plumes formed at neighboring needles in quiescent water. Two sets of needle pairs, one with 1.5mm and 0.8mm inner diameters and the other with the equal 1.5mm inner diameters, were separately used as the bubble pair injectors in the experiments. Consequently, four typical patterns of bubble plumes interaction could be observed in the two cases of needle pair matches. Through measuring the pressure pulses radiated by the bubble pairs immediately after their 'pinching-off ' and by making use of a sophisticated relation between oscillation frequency of volume mode and radius of gas bubble, the detachment size of the bubble plumes have been determined from the amplitude/frequency spectrum of the sound pressure pulses. The experimental results demonstrate that the acoustical method is valid in both of the interacting and non-interacting circumstances in bubble field and the bubble size measurements by this acoustical method agree well with the measurements from photographic analysis. Finally, a comparison has been made on the strong and weak points of the acoustical method with the other size determination methods.展开更多
There has been close relationship between English test method and teaching method. When we make great efforts to reform the English teaching method we should improve the English test method. In this way, we can increa...There has been close relationship between English test method and teaching method. When we make great efforts to reform the English teaching method we should improve the English test method. In this way, we can increase the test efficiency, trustiness, English teaching quality and evaluation function, to transform the teaching from examination-oriented education into quality education.展开更多
Potency is one of the most important indexes of inactivated vaccines.A number of methods have been established to assay the potency,of which the NIH test and single-dose mouse protection test are the "prescribed ...Potency is one of the most important indexes of inactivated vaccines.A number of methods have been established to assay the potency,of which the NIH test and single-dose mouse protection test are the "prescribed methods".Here,we report a method to semi-quantitatively assay the potency of an inactivated rabies vaccine,which uses fewer animals and takes less time to complete.Depending on the quality requirements of a vaccine(e.g.minimum potency),a rabies reference vaccine is,for example,diluted to the minimum potency,and 50 μL of the dilution is taken to inoculate 10 mice.The same amount of the test rabies vaccine is inoculated into another 10 mice.After two weeks,all mice are bled and serum samples are assayed for viral neutralizing antibody by the fluorescent antibody virus neutralization(FAVN) test.By comparing the median and interquartile range of antibody titers of the reference vaccine with those of the test vaccine,the test vaccine potency can be semi-quantitatively judged as to whether it is in accord with the required quality.The reliability of this method was also confirmed in dogs.The procedure can be recommended for batch potency testing during inactivated rabies vaccine production.展开更多
The regional stress field and seismic dynamics along the border zone between Fujian, Guangdong and Jiangxi Provinces are studied based on the seismo-geological data,GPS measurement, and seismicity. The results show th...The regional stress field and seismic dynamics along the border zone between Fujian, Guangdong and Jiangxi Provinces are studied based on the seismo-geological data,GPS measurement, and seismicity. The results show that: (1) the principal compressional stress of the stress field is oriented in NW-SE direction and the principal extensional stress is in NE-SW direction; (2) the WNW-ward compression and collision of the Philippine Sea Plate to the eastern coast of Taiwan Island are the most direct and most important dynamic source for preparation and occurrence of strong earthquakes in the Taiwan Region and along the border zone between Fujian, Guangdong and Jiangxi Provinces.展开更多
The clearance of the hemisphere dynamic pressure motor is small and difficult to measure, the measurement method of micro clearance is studied. The shortcomings of the original measurement method are analyzed, and a c...The clearance of the hemisphere dynamic pressure motor is small and difficult to measure, the measurement method of micro clearance is studied. The shortcomings of the original measurement method are analyzed, and a clearance measuring device for the hemisphere dynamic pressure motor is designed, which improves the measurement efficiency and stability.展开更多
The article uses the psychological measurement, literature review, educational practices and other research methods; it studied experimentally sports games teaching on infant mental health. The results showed that: s...The article uses the psychological measurement, literature review, educational practices and other research methods; it studied experimentally sports games teaching on infant mental health. The results showed that: sports games after the implementation of a semester teaching methods, students 'mental health after the experiment each index scores generally declined, sports games teaching on infant mental health has a positive role in promoting; especially abnormal psychology students' psychological problems have a very good therapeutic effect; the impact of teaching methods on students' mental health has no gender differences.展开更多
Due to the complexity of economic system and the interactive effects between all kinds of economic variables and foreign trade, it is not easy to predict foreign trade volume. However, the difficulty in predicting for...Due to the complexity of economic system and the interactive effects between all kinds of economic variables and foreign trade, it is not easy to predict foreign trade volume. However, the difficulty in predicting foreign trade volume is usually attributed to the limitation of many conventional forecasting models. To improve the prediction performance, the study proposes a novel kernel-based ensemble learning approach hybridizing econometric models and artificial intelligence (AI) models to predict China's foreign trade volume. In the proposed approach, an important econometric model, the co-integration-based error correction vector auto-regression (EC-VAR) model is first used to capture the impacts of all kinds of economic variables on Chinese foreign trade from a multivariate linear anal- ysis perspective. Then an artificial neural network (ANN) based EC-VAR model is used to capture the nonlinear effects of economic variables on foreign trade from the nonlinear viewpoint. Subsequently, for incorporating the effects of irregular events on foreign trade, the text mining and expert's judgmental adjustments are also integrated into the nonlinear ANN-based EC-VAR model. Finally, all kinds of economic variables, the outputs of linear and nonlinear EC-VAR models and judgmental adjustment model are used as input variables of a typical kernel-based support vector regression (SVR) for en- semble prediction purpose. For illustration, the proposed kernel-based ensemble learning methodology hybridizing econometric techniques and AI methods is applied to China's foreign trade volume predic- tion problem. Experimental results reveal that the hybrid econometric-AI ensemble learning approach can significantly improve the prediction performance over other linear and nonlinear models listed in this study.展开更多
The difficulty in crude oil price forecasting, due to inherent complexity, has attracted much attention of academic researchers and business practitioners. Various methods have been tried to solve the problem of forec...The difficulty in crude oil price forecasting, due to inherent complexity, has attracted much attention of academic researchers and business practitioners. Various methods have been tried to solve the problem of forecasting crude oil prices. However, all of the existing models of prediction can not meet practical needs. Very recently, Wang and Yu proposed a new methodology for handling complex systems-TEI@I methodology by means of a systematic integration of text mining, econometrics and intelligent techniques.Within the framework of TEI@I methodology, econometrical models are used to model the linear components of crude oil price time series (i.e., main trends) while nonlinear components of crude oil price time series (i.e., error terms) are modelled by using artificial neural network (ANN) models. In addition, the impact of irregular and infrequent future events on crude oil price is explored using web-based text mining (WTM) and rule-based expert systems (RES) techniques. Thus, a fully novel nonlinear integrated forecasting approach with error correction and judgmental adjustment is formulated to improve prediction performance within the framework of the TEI@I methodology. The proposed methodology and the novel forecasting approach are illustrated via an example.展开更多
We report an electrochemically assisted mechanically controllable break junction (EC-MCBJ) approach to investigating single molecule conductance. Electrode pairs connected with a gold nanobridge were fabricated by e...We report an electrochemically assisted mechanically controllable break junction (EC-MCBJ) approach to investigating single molecule conductance. Electrode pairs connected with a gold nanobridge were fabricated by electrochemical deposition and then mounted on a homebuilt MCBJ platform. A large number of Au- molecule-Au junctions were produced sequentially by repeated breaking and reconnecting of the gold nanobridge. In order to measure their single molecule conductance, statistical conductance histograms were generated for benzene-l,4-dithiol (BDT) and 4,4'-bipyridine (BPY). The values extracted from these histograms were found to be in the same range as values previously reported in the literature. Our method is distinct from the ones used to acquire these previously reported literature values, however, in that it is faster, simpler, more cost-effective, and changing the electrode material is more convenient.展开更多
Long-term forecasts of pest pressure are central to the effective managementof many agricultural insect pests. In the eastern cropping regions of Australia, seriousinfestations of Helicoverpa punctigera (Wallengren) a...Long-term forecasts of pest pressure are central to the effective managementof many agricultural insect pests. In the eastern cropping regions of Australia, seriousinfestations of Helicoverpa punctigera (Wallengren) and H. armigera (Hiibner)(Lepidoptera:Noctuidae) are experienced annually. Regression analyses of a long series of light-trap catches ofadult moths were used to describe the seasonal dynamics of both species. The size of the springgeneration in eastern cropping zones could be related to rainfall in putative source areas in inlandAustralia. Subsequent generations could be related to the abundance of various crops inagricultural areas, rainfall and the magnitude of the spring population peak. As rainfall figuredprominently as a predictor variable, and can itself be predicted using the Southern OscillationIndex (SOI), trap catches were also related to this variable. The geographic distribution of eachspecies was modelled in relation to climate and CLIMEX was used to predict temporal variation inabundance at given putative source sites in inland Australia using historical meteorological data.These predictions were then correlated with subsequent pest abundance data in a major croppingregion. The regression-based and bio-climatic-based approaches to predicting pest abundance arecompared and their utility in predicting and interpreting pest dynamics are discussed.展开更多
Sequence assembling is an important step for bioinformatics study.With the help of next generation sequencing(NGS)technology,high throughput DNA fragment(reads)can be randomly sampled from DNA or RNA molecular sequenc...Sequence assembling is an important step for bioinformatics study.With the help of next generation sequencing(NGS)technology,high throughput DNA fragment(reads)can be randomly sampled from DNA or RNA molecular sequence.However,as the positions of reads being sampled are unknown,assembling process is required for combining overlapped reads to reconstruct the original DNA or RNA sequence.Compared with traditional Sanger sequencing methods,although the throughput of NGS reads increases,the read length is shorter and the error rate is higher.It introduces several problems in assembling.Moreover,paired-end reads instead of single-end reads can be sampled which contain more information.The existing assemblers cannot fully utilize this information and fails to assemble longer contigs.In this article,we will revisit the major problems of assembling NGS reads on genomic,transcriptomic,metagenomic and metatranscriptomic data.We will also describe our IDBA package for solving these problems.IDBA package has adopted several novel ideas in assembling,including using multiple k,local assembling and progressive depth removal.Compared with existence assemblers,IDBA has better performance on many simulated and real sequencing datasets.展开更多
基金supported by the National Natural Science Foundation of China under the Grants Nos. 40633016 and 40433007
文摘As a powerful tool to diagnose vertical motion, frontogenesis, and secondary circulation, the Q vector and its divergence are widely used. However, little attention has been given to the curl of Q vector. In this paper, a new set of analyses combining the divergence of the Q vector (DQ) with the vertical component of the curl of the Q vector (VQ) is applied to a Northeastern cold vortex rainfall case. From the derivation, it was found that the expressions of the Q vectors and their divergences in saturated moist flow (DQm) differ from those of dry and unsaturated moist atmosphere (DQ), while the VQs of various background flows are exactly the same, which largely simplified the analyses. This case study showed that, compared with the DQ, not only can the DQm diagnose precipitation more effectively, but the VQ may also be indicative of precipitation (especially for heavy rainfall and strong convection) because of its direct, close relationship with ageostrophic motion. Thus, the VQ may be computed and analyzed with ease, and may serve as a useful tool for analyses of precipitation and strong convective svstems.
文摘A precise zoom magnification is important for semiconductor industry and biomedical research. A novel measurement method is demonstrated for optical zoom magnification measurement in this paper. The magnification is obtained by pattern correction between barcode image formed by optical zoom and reference image generated by an ideal optical model. Measurement accuracy which is better than 0.06% has been achieved for optical zoom magnification. Compared with traditional concept, the measurement results are only dependent on two line edges. The barcode correlation method can achieve higher accuracy and better robustness by using the information over the whole field of view.
基金Supported by the National Natural Science Foundation of China (No.60473021)
文摘Characteristic measurement of contact discharge currents are made through a hand-held metal rod from charged human body. Correlation coefficients are obtained, through Statistic Package for Social Science (SPSS), for various charge voltages, which is based on the effect test of electrode contact approach speeds on discharge current parameters of current peaks, maximum rising slope and spark lengths. Discharge parameters at charge voltage 300V are independent on approach speed. For charge voltages equal to and higher than 500V, the contact approach speed has strong positive cor- relation with discharge parameters of the peak current and the maximum rising slope, whereas has strong negative correlation with the spark length.
基金Supported bythe National Natural Science Foundation of China (No.40637034, No. 40574004), the National 863 Program of China (No. 2006AA12Z211).
文摘The fictitious compress recovery approach is introduced, which could be applied to the establishment of the Rungerarup theorem, the determination of the Bjerhammar's fictitious gravity anomaly, the solution of the "downward con- tinuation" problem of the gravity field, the confirmation of the convergence of the spherical harmonic expansion series of the Earth's potential field, and the gravity field determination in three cases: gravitational potential case, gravitation case, and gravitational gradient case. Several tests using simulation experiments show that the fictitious compress recovery approach shows promise in physical geodesy applications.
基金Supported by The John S Latsis Public Benefit FoundationThe Hellenic Society of Medical Oncology
文摘AIM:To detect of colorectal cancer(CRC) circulating tumour cells(CTCs) surface antigens,we present an assay incorporating cadmium selenide quantum dots(QDs) in these paper.METHODS:The principle of the assay is the immunomagnetic separation of CTCs from body fluids in conjunction with QDs,using specific antibody biomarkers:epithelial cell adhesion molecule antibody,and monoclonal cytokeratin 19 antibody.The detection signal was acquired from the fluorescence signal of QDs.For the evaluation of the performance,the method under study was used to isolate the human colon adenocarcinoma cell line(DLD-1) and CTCs from CRC patients' peripheral blood.RESULTS:The minimum detection limit of the assay was defined to 10 DLD-1 CRC cells/mL as fluorescence was measured with a spectrofluorometer.Fluorescenceactivated cell sorting analysis and Real Time RT-PCR,they both have also been used to evaluate the performance of the described method.In conclusion,we developed a simple,sensitive,efficient and of lower cost(than the existing ones) method for the detection of CRC CTCs in human samples.We have accomplished these results by using magnetic bead isolation and subsequent QD fluorescence detection.CONCLUSION:The method described here can be easily adjusted for any other protein target of either the CTC or the host.
基金supported by National Natural Science Foundation of China and the Science Foundation of Sun Yet-Sen University
文摘The compact form of the electroweak chiral Lagrangian is a reformulation of its original form and is expressed in terms of chiral rotated electroweak gauge fields, which is crucial for relating the information of underlying theories to the coefficients of the low-energy effective Lagrangian. However the compact form obtained in previous works is not complete. In this letter we add several new chiral invariant terms to it and discuss the contributions of these terms to the original electroweak chiral Lagrangian.
基金Supported by the Post-Doctorate Science Foundation.
文摘Detachment size determination with an acoustic method has been carried out for two interacting bubble plumes formed at neighboring needles in quiescent water. Two sets of needle pairs, one with 1.5mm and 0.8mm inner diameters and the other with the equal 1.5mm inner diameters, were separately used as the bubble pair injectors in the experiments. Consequently, four typical patterns of bubble plumes interaction could be observed in the two cases of needle pair matches. Through measuring the pressure pulses radiated by the bubble pairs immediately after their 'pinching-off ' and by making use of a sophisticated relation between oscillation frequency of volume mode and radius of gas bubble, the detachment size of the bubble plumes have been determined from the amplitude/frequency spectrum of the sound pressure pulses. The experimental results demonstrate that the acoustical method is valid in both of the interacting and non-interacting circumstances in bubble field and the bubble size measurements by this acoustical method agree well with the measurements from photographic analysis. Finally, a comparison has been made on the strong and weak points of the acoustical method with the other size determination methods.
文摘There has been close relationship between English test method and teaching method. When we make great efforts to reform the English teaching method we should improve the English test method. In this way, we can increase the test efficiency, trustiness, English teaching quality and evaluation function, to transform the teaching from examination-oriented education into quality education.
基金the China National"863"Program(Approval No.2011AA10A212)Special Fund for Agro-Scientific Research in the Public Interest(ApprovalNo.201203056)
文摘Potency is one of the most important indexes of inactivated vaccines.A number of methods have been established to assay the potency,of which the NIH test and single-dose mouse protection test are the "prescribed methods".Here,we report a method to semi-quantitatively assay the potency of an inactivated rabies vaccine,which uses fewer animals and takes less time to complete.Depending on the quality requirements of a vaccine(e.g.minimum potency),a rabies reference vaccine is,for example,diluted to the minimum potency,and 50 μL of the dilution is taken to inoculate 10 mice.The same amount of the test rabies vaccine is inoculated into another 10 mice.After two weeks,all mice are bled and serum samples are assayed for viral neutralizing antibody by the fluorescent antibody virus neutralization(FAVN) test.By comparing the median and interquartile range of antibody titers of the reference vaccine with those of the test vaccine,the test vaccine potency can be semi-quantitatively judged as to whether it is in accord with the required quality.The reliability of this method was also confirmed in dogs.The procedure can be recommended for batch potency testing during inactivated rabies vaccine production.
文摘The regional stress field and seismic dynamics along the border zone between Fujian, Guangdong and Jiangxi Provinces are studied based on the seismo-geological data,GPS measurement, and seismicity. The results show that: (1) the principal compressional stress of the stress field is oriented in NW-SE direction and the principal extensional stress is in NE-SW direction; (2) the WNW-ward compression and collision of the Philippine Sea Plate to the eastern coast of Taiwan Island are the most direct and most important dynamic source for preparation and occurrence of strong earthquakes in the Taiwan Region and along the border zone between Fujian, Guangdong and Jiangxi Provinces.
文摘The clearance of the hemisphere dynamic pressure motor is small and difficult to measure, the measurement method of micro clearance is studied. The shortcomings of the original measurement method are analyzed, and a clearance measuring device for the hemisphere dynamic pressure motor is designed, which improves the measurement efficiency and stability.
文摘The article uses the psychological measurement, literature review, educational practices and other research methods; it studied experimentally sports games teaching on infant mental health. The results showed that: sports games after the implementation of a semester teaching methods, students 'mental health after the experiment each index scores generally declined, sports games teaching on infant mental health has a positive role in promoting; especially abnormal psychology students' psychological problems have a very good therapeutic effect; the impact of teaching methods on students' mental health has no gender differences.
基金the National Natural Science Foundation of China under Grant Nos.70601029 and 70221001the Knowledge Innovation Program of the Chinese Academy of Sciences under Grant Nos.3547600,3046540,and 3047540the Strategy Research Grant of City University of Hong Kong under Grant No.7001806
文摘Due to the complexity of economic system and the interactive effects between all kinds of economic variables and foreign trade, it is not easy to predict foreign trade volume. However, the difficulty in predicting foreign trade volume is usually attributed to the limitation of many conventional forecasting models. To improve the prediction performance, the study proposes a novel kernel-based ensemble learning approach hybridizing econometric models and artificial intelligence (AI) models to predict China's foreign trade volume. In the proposed approach, an important econometric model, the co-integration-based error correction vector auto-regression (EC-VAR) model is first used to capture the impacts of all kinds of economic variables on Chinese foreign trade from a multivariate linear anal- ysis perspective. Then an artificial neural network (ANN) based EC-VAR model is used to capture the nonlinear effects of economic variables on foreign trade from the nonlinear viewpoint. Subsequently, for incorporating the effects of irregular events on foreign trade, the text mining and expert's judgmental adjustments are also integrated into the nonlinear ANN-based EC-VAR model. Finally, all kinds of economic variables, the outputs of linear and nonlinear EC-VAR models and judgmental adjustment model are used as input variables of a typical kernel-based support vector regression (SVR) for en- semble prediction purpose. For illustration, the proposed kernel-based ensemble learning methodology hybridizing econometric techniques and AI methods is applied to China's foreign trade volume predic- tion problem. Experimental results reveal that the hybrid econometric-AI ensemble learning approach can significantly improve the prediction performance over other linear and nonlinear models listed in this study.
基金This research is partially supported by NSFC, CAS, RGC of Hong Kong and Ministry of Education and Technology of Japan
文摘The difficulty in crude oil price forecasting, due to inherent complexity, has attracted much attention of academic researchers and business practitioners. Various methods have been tried to solve the problem of forecasting crude oil prices. However, all of the existing models of prediction can not meet practical needs. Very recently, Wang and Yu proposed a new methodology for handling complex systems-TEI@I methodology by means of a systematic integration of text mining, econometrics and intelligent techniques.Within the framework of TEI@I methodology, econometrical models are used to model the linear components of crude oil price time series (i.e., main trends) while nonlinear components of crude oil price time series (i.e., error terms) are modelled by using artificial neural network (ANN) models. In addition, the impact of irregular and infrequent future events on crude oil price is explored using web-based text mining (WTM) and rule-based expert systems (RES) techniques. Thus, a fully novel nonlinear integrated forecasting approach with error correction and judgmental adjustment is formulated to improve prediction performance within the framework of the TEI@I methodology. The proposed methodology and the novel forecasting approach are illustrated via an example.
文摘We report an electrochemically assisted mechanically controllable break junction (EC-MCBJ) approach to investigating single molecule conductance. Electrode pairs connected with a gold nanobridge were fabricated by electrochemical deposition and then mounted on a homebuilt MCBJ platform. A large number of Au- molecule-Au junctions were produced sequentially by repeated breaking and reconnecting of the gold nanobridge. In order to measure their single molecule conductance, statistical conductance histograms were generated for benzene-l,4-dithiol (BDT) and 4,4'-bipyridine (BPY). The values extracted from these histograms were found to be in the same range as values previously reported in the literature. Our method is distinct from the ones used to acquire these previously reported literature values, however, in that it is faster, simpler, more cost-effective, and changing the electrode material is more convenient.
文摘Long-term forecasts of pest pressure are central to the effective managementof many agricultural insect pests. In the eastern cropping regions of Australia, seriousinfestations of Helicoverpa punctigera (Wallengren) and H. armigera (Hiibner)(Lepidoptera:Noctuidae) are experienced annually. Regression analyses of a long series of light-trap catches ofadult moths were used to describe the seasonal dynamics of both species. The size of the springgeneration in eastern cropping zones could be related to rainfall in putative source areas in inlandAustralia. Subsequent generations could be related to the abundance of various crops inagricultural areas, rainfall and the magnitude of the spring population peak. As rainfall figuredprominently as a predictor variable, and can itself be predicted using the Southern OscillationIndex (SOI), trap catches were also related to this variable. The geographic distribution of eachspecies was modelled in relation to climate and CLIMEX was used to predict temporal variation inabundance at given putative source sites in inland Australia using historical meteorological data.These predictions were then correlated with subsequent pest abundance data in a major croppingregion. The regression-based and bio-climatic-based approaches to predicting pest abundance arecompared and their utility in predicting and interpreting pest dynamics are discussed.
基金supported in part by Hong Kong GRF HKU 7111/12E, 719611EShenzhen Basic Research Project JCYJ20120618143038947 (SIRI/04/04/2012/05)Outstanding Researcher Award (102009124).
文摘Sequence assembling is an important step for bioinformatics study.With the help of next generation sequencing(NGS)technology,high throughput DNA fragment(reads)can be randomly sampled from DNA or RNA molecular sequence.However,as the positions of reads being sampled are unknown,assembling process is required for combining overlapped reads to reconstruct the original DNA or RNA sequence.Compared with traditional Sanger sequencing methods,although the throughput of NGS reads increases,the read length is shorter and the error rate is higher.It introduces several problems in assembling.Moreover,paired-end reads instead of single-end reads can be sampled which contain more information.The existing assemblers cannot fully utilize this information and fails to assemble longer contigs.In this article,we will revisit the major problems of assembling NGS reads on genomic,transcriptomic,metagenomic and metatranscriptomic data.We will also describe our IDBA package for solving these problems.IDBA package has adopted several novel ideas in assembling,including using multiple k,local assembling and progressive depth removal.Compared with existence assemblers,IDBA has better performance on many simulated and real sequencing datasets.