Commercial purity and high purity titanium sheets were initially strained by a new technique, named as friction roll surface processing (FRSP). Severe strain was imposed into the surface layer and strain gradient wa...Commercial purity and high purity titanium sheets were initially strained by a new technique, named as friction roll surface processing (FRSP). Severe strain was imposed into the surface layer and strain gradient was formed through the thickness of the sheet. The microstructure and texture in as-strained state were investigated by optical microscopy and X-ray diffraction technique On the surface of the sheets, ultra-fine grains were found to have a sharp texture with a preferred orientation strongly related to the FRSP direction. The evolution of microstructure and crystallographic texture of FRSPed samples during recrystallization were also studied by electron back-scattered diffraction (EBSD) technique after being annealed at selected temperatures and time. The results indicated that the preferred orientations resulting from FRSP and annealing in the surface layer were formed during rolling and its recrystallization textures were reduced by FRSP. In addition, the texture evolved stably without change in main components during the annealing.展开更多
The rapidness and stability of background extraction from image sequences are incompatible,that is,when a conventional Gaussian mixture models (GMM)is used to rebuild the background,if the background regions of the sc...The rapidness and stability of background extraction from image sequences are incompatible,that is,when a conventional Gaussian mixture models (GMM)is used to rebuild the background,if the background regions of the scene are changed,the extracted background becomes bad until the transition is over. A novel adaptive method is presented to adjust the learning rate of GMM in a Hilbert space. The background extraction is treated as a process of approaching to a certain point in the Hilbert space,so the real-time learning rate can be obtained by calculating the distance between the two adjacent extracted background images,and a judgment method of the stability of background is got too. Compared with conventional GMM,the method has both high rapidness and good stability at the same time,and it can adjust the learning rate online. The experiment shows that it is better than conventional GMM,especially in the transition process of background extraction.展开更多
This study investigated the effects of H2O2 treatment on xanthate interaction and flotation separation of chalcopyrite and pyrite by making use of a series of laboratory flotation experiments and surface analysis tech...This study investigated the effects of H2O2 treatment on xanthate interaction and flotation separation of chalcopyrite and pyrite by making use of a series of laboratory flotation experiments and surface analysis techniques.Flotation test results showed that H2O2 treatment influenced the flotation behaviors of the two minerals;however,flotation of pyrite was depressed more significantly than that of the chalcopyrite.Under well-controlled H2O2 concentration,the selective separation of chalcopyrite from pyrite was realized at pH 9.0,at which the recovery of chalcopyrite was over 84%and that of pyrite was less than 24%.Zeta potential,UV-visible and IR spectrum measurements revealed that the collector interacted differently with the two minerals after H2O2 treatment,and the surface of chalcopyrite adsorbed much greater amount of xanthate than that of the pyrite.IR and XPS analyses showed that the H2O2 treatment significantly changed the surface properties of pyrite to very hydrophilic species that inhibited the adsorption of collector and thus depressed the floatability of pyrite.While,the surface of chalcopyrite remained mildly inert to H2O2,as a result,the adsorption of xanthate and its oxidation to dixanthogen were very effective,which enhanced the flotation of chalcopyrite.展开更多
We discuss some methods for constructing recommender systems. An important feature of the methods studied here is that we assume the availability of a description, representation, of the objects being considered for r...We discuss some methods for constructing recommender systems. An important feature of the methods studied here is that we assume the availability of a description, representation, of the objects being considered for recommendation. The approaches studied here differ from collaborative filtering in that we only use preferences information from the individual for whom we are providing the recommendation and make no use the preferences of other collaborators. We provide a detailed discussion of the construction of the representation schema used. We consider two sources of information about the users preferences. The first are direct statements about the type of objects the user likes. The second source of information comes from ratings of objects which the user has experienced.展开更多
A set of integrated Orthogonal Frequency Division Multiplexing(OFDM) modulation and demodulation system is proposed and its performance is verified in reference to the standard of IEEE802.16a for WMAN.The design,combi...A set of integrated Orthogonal Frequency Division Multiplexing(OFDM) modulation and demodulation system is proposed and its performance is verified in reference to the standard of IEEE802.16a for WMAN.The design,combined with analogy front-end,adopts Texas Instrument(TI) Company's 6701 evaluation module(EVM) to construct digital Intermediate Frequency(IF) platform.A DSP-based baseband processing software module is embedded into the system.The proposed scheme makes it possible for users to select various software modules to set up connections with different throughput performance.Taking into account the given hardware configuration,the design aims to optimize the algorithm modules to accomplish better system performance.展开更多
In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the prop...In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the proposed RDWC are investigated. Four control structures including composition and temperature controls are proposed. The feed forward controllers are employed in the four control strategies to shorten the dynamic response time, reduce the maximum deviations and offer an immediate adjustment. The control structures are compared by applying them into the RDWC system with 20% disturbances in both the feed flow rate and the feed compositions, and the results are discussed.展开更多
This paper reviews the requirements for Software Defi ned Radio (SDR) systems for high-speed wireless applications and compares how well the different technology choices available-from ASICs, FPGAs to digital signal p...This paper reviews the requirements for Software Defi ned Radio (SDR) systems for high-speed wireless applications and compares how well the different technology choices available-from ASICs, FPGAs to digital signal processors (DSPs) and general purpose processors (GPPs) - meet them.展开更多
It has been reported that natural cellulose (cellulose I) can not be oxidized by TEMPO - NaOCI - NaBr system, one of TEMPO-mediated selective oxidant systems, but regenerated cellulose (cellulose Ⅱ ) can be compl...It has been reported that natural cellulose (cellulose I) can not be oxidized by TEMPO - NaOCI - NaBr system, one of TEMPO-mediated selective oxidant systems, but regenerated cellulose (cellulose Ⅱ ) can be completely selectively oxidized. In the present work, natural cellulose pulp was treated with NaOH solution, which concentration is lower than 20 wt%. The alkaline celluloses obtained were oxidized by TEMPO - NaOCI - NaBr system and the factors which influence the selective oxidation reaction rate have been investigated. The structure of the oxidized products has been characterized by Fourier transform-infrared (FTIR), nuclear magenatic resonace (NMR) and wide angle X-ray diffraction (WAXD) methods, and their adsorption properties for Cu^2+ and Cd^2+ in aqueous solutions have been preliminarily examined. The results show that after the alkaline treatment, the primary hydroxyl at C6 position of natural cellulose can be selectively oxidized to carboxyl group in the reaction medium at pH 10.8, the oxidation rate becomes greater with the NaOH concentration and alkaline treatment time increasing. The alkaline treatment has a great effect on the crystal structure of natural cellulose, but the crystal structure of alkaline cellulose keeps almost unchanged after oxidation. The adsorption capacity is enhanced by introducing carboxyl groups into the cellulose macromolecular chains.展开更多
Compared with the traditional method of adding sentences to get summary in multi-document summarization,a two-stage sentence selection approach based on deleting sentences in acandidate sentence set to generate summar...Compared with the traditional method of adding sentences to get summary in multi-document summarization,a two-stage sentence selection approach based on deleting sentences in acandidate sentence set to generate summary is proposed,which has two stages,the acquisition of acandidate sentence set and the optimum selection of sentence.At the first stage,the candidate sentenceset is obtained by redundancy-based sentence selection approach.At the second stage,optimum se-lection of sentences is proposed to delete sentences in the candidate sentence set according to itscontribution to the whole set until getting the appointed summary length.With a test corpus,theROUGE value of summaries gotten by the proposed approach proves its validity,compared with thetraditional method of sentence selection.The influence of the token chosen in the two-stage sentenceselection approach on the quality of the generated summaries is analyzed.展开更多
Delay diversity is an effective transmit diversity technique to combat adverse effects of fading. Thus far, previous work in delay diversity assumed that perfect estimates of current channel fading conditions are ava...Delay diversity is an effective transmit diversity technique to combat adverse effects of fading. Thus far, previous work in delay diversity assumed that perfect estimates of current channel fading conditions are available at the receiver and training symbols are required to estimate the channel from the transmitter to the receiver. However, increasing the number of the antennas increases the required training interval and reduces the available time with in whichdata may be transmitted. Learning the channel coefficients becomes increasingly difficult for the frequency selective channels. In this paper, with the subspace method and the delay character of delay diversity, a channel estimation method is proposed, which does not use training symbols. It addresses the transmit diversity for a frequency selective channel from a single carrier perspective in the form of a simple equivalent flat fading model. Monte Carlo simulations give the performance of channel estimation and the performance comparison of our channel-estimation-based detector with decision feedback equalization, which uses the perfect channel information.展开更多
The paper presents the research for the purpose of selecting microorganisms into the production process of "chao" to improve the quality of "chao" products and ensure food safety. Several analytical methods such a...The paper presents the research for the purpose of selecting microorganisms into the production process of "chao" to improve the quality of "chao" products and ensure food safety. Several analytical methods such as determination of formal nitrogen, determination of the protease hydrolysis activity, sensory evaluation method, experimental procedure, methods of analysis and processing of empirical data were used in this study. The findings showed that two out of four selected microorganism strains (one strain of fungi and three strains of bacteria denoted NM1, VK1, VK2, VK3, respectively) were the most appropriate for the cooperation among them and the production of %hao", which were coded NM1 and VK1. The suitable mixing proportion of strains of NM1 and VK1 was determined at 1:1.25, compatible with the 1:100 ratio of the varieties of microorganisms (in powder form) to tofu.展开更多
Compounds containing Cr (VI) ion are widely used for chemical industry, paints, dyes, and other applications. Because of commonly known toxicity of Cr (VI) ion, Cr (VI) is one of the important check items for qu...Compounds containing Cr (VI) ion are widely used for chemical industry, paints, dyes, and other applications. Because of commonly known toxicity of Cr (VI) ion, Cr (VI) is one of the important check items for quality of water in natural river or industrial waste water. Although the only method for selective detection for Cr (VI) ion is diphenylcarbazide, of which pretreatment spends long time according to the regulat^ons by the Ministry of Environment, Japan. Herein we develop a new and simple pretreatment for the job site and suitable for education and attempt to apply for analysis of the soil in Tama River actually.展开更多
Livestock farm waste contributes substantially to annual worldwide emissions of GHG (Greenhouse Gases), including CH4 (Methane) and CO2 (Carbon Dioxide). However, despite evidence of global climate change and it...Livestock farm waste contributes substantially to annual worldwide emissions of GHG (Greenhouse Gases), including CH4 (Methane) and CO2 (Carbon Dioxide). However, despite evidence of global climate change and its adverse health effects, studies on anthropogenic contributions to the increasing levels of GHG, particularly from livestock waste management practices, have not been adequately explored, especially in less developed countries. This study determined waste management practices and outdoor levels of CH4 and CO2 at three selected livestock farms (A-C) in Ibadan, Oyo State, Nigeria. Each study farm consisted of poultry, cattle and pig units. A 30-point observational checklist documented adequacy of solid waste management practices. Ambient concentrations of CH4 and CO2 at farm buildings and at waste disposal sites were monitored every other day, twice each day of monitoring (morning and evening hours), for eight weeks during months of September-November in 2013. Average scores for the waste management practices for Farms A-C were 29.6%, 33.3% and 18.5%, respectively. Morning and evening CH4 concentrations in parts per million (ppm) at main buildings of Farms A-C were 2,538 ± 773 and 1,916 ± 662, 2,325 ± 773 and 1,180 ± 483, and 2,389 ± 687 and 1,854 ± 571, respectively. Morning and evening CO2 concentrations (ppm) at Farms A-C main buildings were 350 ± 130 and 330 ± 110, 470 ± 100 and 440 ± 100, and 430 ± 80 and 400 ± 70, respectively. Morning and evening CH4 concentrations (ppm) at Farms A-C waste disposal sites were 2,452 ± 495 and 1,614 ± 372, 1,527 ± 390 and 1,736 ± 269, and 2,345 ± 615 and 1,690 ± 387, respectively. Morning and evening CO2 concentrations (ppm) at Farms A-C waste disposal sites were 330 ± 90, 370 ± 60 and 350 ± 30, respectively. Waste management practices were inadequate; solid waste management practices like infrequent evacuation of slurry waste and open burning of waste may have contributed to the production of CH4 and CO2. This study suggested proper handling, removal and disposal of farm waste which can reduce production of GHGs like CH4 and CO2.展开更多
This paper considers variable selection for moment restriction models. We propose a penalized empirical likelihood (PEL) approach that has desirable asymptotic properties comparable to the penalized likelihood appro...This paper considers variable selection for moment restriction models. We propose a penalized empirical likelihood (PEL) approach that has desirable asymptotic properties comparable to the penalized likelihood approach, which relies on a correct parametric likelihood specification. In addition to being consistent and having the oracle property, PEL admits inference on parameter without having to estimate its estimator's covariance. An approximate algorithm, along with a consistent BIC-type criterion for selecting the tuning parameters, is provided for FEL. The proposed algorithm enjoys considerable computational efficiency and overcomes the drawback of the local quadratic approximation of nonconcave penalties. Simulation studies to evaluate and compare the performances of our method with those of the existing ones show that PEL is competitive and robust. The proposed method is illustrated with two real examples.展开更多
Feature selection is an important approach to dimensionality reduction in the field of text classification. Because of the difficulty in handling the problem that the selected features always contain redundant informa...Feature selection is an important approach to dimensionality reduction in the field of text classification. Because of the difficulty in handling the problem that the selected features always contain redundant information, we propose a new simple feature selection method, which can effectively filter the redundant features. First, to calculate the relationship between two words, the definitions of word frequency based relevance and correlative redundancy are introduced. Furthermore, an optimal feature selection(OFS) method is chosen to obtain a feature subset FS1. Finally, to improve the execution speed, the redundant features in FS1 are filtered by combining a predetermined threshold, and the filtered features are memorized in the linked lists. Experiments are carried out on three datasets(Web KB, 20-Newsgroups, and Reuters-21578) where in support vector machines and na?ve Bayes are used. The results show that the classification accuracy of the proposed method is generally higher than that of typical traditional methods(information gain, improved Gini index, and improved comprehensively measured feature selection) and the OFS methods. Moreover, the proposed method runs faster than typical mutual information-based methods(improved and normalized mutual information-based feature selections, and multilabel feature selection based on maximum dependency and minimum redundancy) while simultaneously ensuring classification accuracy. Statistical results validate the effectiveness of the proposed method in handling redundant information in text classification.展开更多
基金support in part by Grant-in-aid for Scientific Research from the Japan Society for Promotion of Science under Contract No. 16560605
文摘Commercial purity and high purity titanium sheets were initially strained by a new technique, named as friction roll surface processing (FRSP). Severe strain was imposed into the surface layer and strain gradient was formed through the thickness of the sheet. The microstructure and texture in as-strained state were investigated by optical microscopy and X-ray diffraction technique On the surface of the sheets, ultra-fine grains were found to have a sharp texture with a preferred orientation strongly related to the FRSP direction. The evolution of microstructure and crystallographic texture of FRSPed samples during recrystallization were also studied by electron back-scattered diffraction (EBSD) technique after being annealed at selected temperatures and time. The results indicated that the preferred orientations resulting from FRSP and annealing in the surface layer were formed during rolling and its recrystallization textures were reduced by FRSP. In addition, the texture evolved stably without change in main components during the annealing.
文摘The rapidness and stability of background extraction from image sequences are incompatible,that is,when a conventional Gaussian mixture models (GMM)is used to rebuild the background,if the background regions of the scene are changed,the extracted background becomes bad until the transition is over. A novel adaptive method is presented to adjust the learning rate of GMM in a Hilbert space. The background extraction is treated as a process of approaching to a certain point in the Hilbert space,so the real-time learning rate can be obtained by calculating the distance between the two adjacent extracted background images,and a judgment method of the stability of background is got too. Compared with conventional GMM,the method has both high rapidness and good stability at the same time,and it can adjust the learning rate online. The experiment shows that it is better than conventional GMM,especially in the transition process of background extraction.
基金Projects(51704329,51705540) supported by the National Natural Science Foundation of ChinaProject(2015CX005) supported by the Innovation Driven Plan of Central South University,China+1 种基金Project(B14034) supported by the National “111” Project,ChinaProject(2018TP1002) supported by the Collaborative Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources,China
文摘This study investigated the effects of H2O2 treatment on xanthate interaction and flotation separation of chalcopyrite and pyrite by making use of a series of laboratory flotation experiments and surface analysis techniques.Flotation test results showed that H2O2 treatment influenced the flotation behaviors of the two minerals;however,flotation of pyrite was depressed more significantly than that of the chalcopyrite.Under well-controlled H2O2 concentration,the selective separation of chalcopyrite from pyrite was realized at pH 9.0,at which the recovery of chalcopyrite was over 84%and that of pyrite was less than 24%.Zeta potential,UV-visible and IR spectrum measurements revealed that the collector interacted differently with the two minerals after H2O2 treatment,and the surface of chalcopyrite adsorbed much greater amount of xanthate than that of the pyrite.IR and XPS analyses showed that the H2O2 treatment significantly changed the surface properties of pyrite to very hydrophilic species that inhibited the adsorption of collector and thus depressed the floatability of pyrite.While,the surface of chalcopyrite remained mildly inert to H2O2,as a result,the adsorption of xanthate and its oxidation to dixanthogen were very effective,which enhanced the flotation of chalcopyrite.
文摘We discuss some methods for constructing recommender systems. An important feature of the methods studied here is that we assume the availability of a description, representation, of the objects being considered for recommendation. The approaches studied here differ from collaborative filtering in that we only use preferences information from the individual for whom we are providing the recommendation and make no use the preferences of other collaborators. We provide a detailed discussion of the construction of the representation schema used. We consider two sources of information about the users preferences. The first are direct statements about the type of objects the user likes. The second source of information comes from ratings of objects which the user has experienced.
文摘A set of integrated Orthogonal Frequency Division Multiplexing(OFDM) modulation and demodulation system is proposed and its performance is verified in reference to the standard of IEEE802.16a for WMAN.The design,combined with analogy front-end,adopts Texas Instrument(TI) Company's 6701 evaluation module(EVM) to construct digital Intermediate Frequency(IF) platform.A DSP-based baseband processing software module is embedded into the system.The proposed scheme makes it possible for users to select various software modules to set up connections with different throughput performance.Taking into account the given hardware configuration,the design aims to optimize the algorithm modules to accomplish better system performance.
基金Supported by the National Basic Research Program of China(2012CB720500)the National Supporting Research Program of China(2013BAA03B01)+1 种基金the National Natural Science Foundation of China(21176178)China Scholarship Council(CSC[2015]3022)
文摘In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the proposed RDWC are investigated. Four control structures including composition and temperature controls are proposed. The feed forward controllers are employed in the four control strategies to shorten the dynamic response time, reduce the maximum deviations and offer an immediate adjustment. The control structures are compared by applying them into the RDWC system with 20% disturbances in both the feed flow rate and the feed compositions, and the results are discussed.
文摘This paper reviews the requirements for Software Defi ned Radio (SDR) systems for high-speed wireless applications and compares how well the different technology choices available-from ASICs, FPGAs to digital signal processors (DSPs) and general purpose processors (GPPs) - meet them.
文摘It has been reported that natural cellulose (cellulose I) can not be oxidized by TEMPO - NaOCI - NaBr system, one of TEMPO-mediated selective oxidant systems, but regenerated cellulose (cellulose Ⅱ ) can be completely selectively oxidized. In the present work, natural cellulose pulp was treated with NaOH solution, which concentration is lower than 20 wt%. The alkaline celluloses obtained were oxidized by TEMPO - NaOCI - NaBr system and the factors which influence the selective oxidation reaction rate have been investigated. The structure of the oxidized products has been characterized by Fourier transform-infrared (FTIR), nuclear magenatic resonace (NMR) and wide angle X-ray diffraction (WAXD) methods, and their adsorption properties for Cu^2+ and Cd^2+ in aqueous solutions have been preliminarily examined. The results show that after the alkaline treatment, the primary hydroxyl at C6 position of natural cellulose can be selectively oxidized to carboxyl group in the reaction medium at pH 10.8, the oxidation rate becomes greater with the NaOH concentration and alkaline treatment time increasing. The alkaline treatment has a great effect on the crystal structure of natural cellulose, but the crystal structure of alkaline cellulose keeps almost unchanged after oxidation. The adsorption capacity is enhanced by introducing carboxyl groups into the cellulose macromolecular chains.
基金the National Natural Science Foundation of China(No.60575041)the High Technology Researchand Development Program of China(No.2006AA01Z150).
文摘Compared with the traditional method of adding sentences to get summary in multi-document summarization,a two-stage sentence selection approach based on deleting sentences in acandidate sentence set to generate summary is proposed,which has two stages,the acquisition of acandidate sentence set and the optimum selection of sentence.At the first stage,the candidate sentenceset is obtained by redundancy-based sentence selection approach.At the second stage,optimum se-lection of sentences is proposed to delete sentences in the candidate sentence set according to itscontribution to the whole set until getting the appointed summary length.With a test corpus,theROUGE value of summaries gotten by the proposed approach proves its validity,compared with thetraditional method of sentence selection.The influence of the token chosen in the two-stage sentenceselection approach on the quality of the generated summaries is analyzed.
基金the National Natural Science Foundation of China (No.69872029)
文摘Delay diversity is an effective transmit diversity technique to combat adverse effects of fading. Thus far, previous work in delay diversity assumed that perfect estimates of current channel fading conditions are available at the receiver and training symbols are required to estimate the channel from the transmitter to the receiver. However, increasing the number of the antennas increases the required training interval and reduces the available time with in whichdata may be transmitted. Learning the channel coefficients becomes increasingly difficult for the frequency selective channels. In this paper, with the subspace method and the delay character of delay diversity, a channel estimation method is proposed, which does not use training symbols. It addresses the transmit diversity for a frequency selective channel from a single carrier perspective in the form of a simple equivalent flat fading model. Monte Carlo simulations give the performance of channel estimation and the performance comparison of our channel-estimation-based detector with decision feedback equalization, which uses the perfect channel information.
文摘The paper presents the research for the purpose of selecting microorganisms into the production process of "chao" to improve the quality of "chao" products and ensure food safety. Several analytical methods such as determination of formal nitrogen, determination of the protease hydrolysis activity, sensory evaluation method, experimental procedure, methods of analysis and processing of empirical data were used in this study. The findings showed that two out of four selected microorganism strains (one strain of fungi and three strains of bacteria denoted NM1, VK1, VK2, VK3, respectively) were the most appropriate for the cooperation among them and the production of %hao", which were coded NM1 and VK1. The suitable mixing proportion of strains of NM1 and VK1 was determined at 1:1.25, compatible with the 1:100 ratio of the varieties of microorganisms (in powder form) to tofu.
文摘Compounds containing Cr (VI) ion are widely used for chemical industry, paints, dyes, and other applications. Because of commonly known toxicity of Cr (VI) ion, Cr (VI) is one of the important check items for quality of water in natural river or industrial waste water. Although the only method for selective detection for Cr (VI) ion is diphenylcarbazide, of which pretreatment spends long time according to the regulat^ons by the Ministry of Environment, Japan. Herein we develop a new and simple pretreatment for the job site and suitable for education and attempt to apply for analysis of the soil in Tama River actually.
文摘Livestock farm waste contributes substantially to annual worldwide emissions of GHG (Greenhouse Gases), including CH4 (Methane) and CO2 (Carbon Dioxide). However, despite evidence of global climate change and its adverse health effects, studies on anthropogenic contributions to the increasing levels of GHG, particularly from livestock waste management practices, have not been adequately explored, especially in less developed countries. This study determined waste management practices and outdoor levels of CH4 and CO2 at three selected livestock farms (A-C) in Ibadan, Oyo State, Nigeria. Each study farm consisted of poultry, cattle and pig units. A 30-point observational checklist documented adequacy of solid waste management practices. Ambient concentrations of CH4 and CO2 at farm buildings and at waste disposal sites were monitored every other day, twice each day of monitoring (morning and evening hours), for eight weeks during months of September-November in 2013. Average scores for the waste management practices for Farms A-C were 29.6%, 33.3% and 18.5%, respectively. Morning and evening CH4 concentrations in parts per million (ppm) at main buildings of Farms A-C were 2,538 ± 773 and 1,916 ± 662, 2,325 ± 773 and 1,180 ± 483, and 2,389 ± 687 and 1,854 ± 571, respectively. Morning and evening CO2 concentrations (ppm) at Farms A-C main buildings were 350 ± 130 and 330 ± 110, 470 ± 100 and 440 ± 100, and 430 ± 80 and 400 ± 70, respectively. Morning and evening CH4 concentrations (ppm) at Farms A-C waste disposal sites were 2,452 ± 495 and 1,614 ± 372, 1,527 ± 390 and 1,736 ± 269, and 2,345 ± 615 and 1,690 ± 387, respectively. Morning and evening CO2 concentrations (ppm) at Farms A-C waste disposal sites were 330 ± 90, 370 ± 60 and 350 ± 30, respectively. Waste management practices were inadequate; solid waste management practices like infrequent evacuation of slurry waste and open burning of waste may have contributed to the production of CH4 and CO2. This study suggested proper handling, removal and disposal of farm waste which can reduce production of GHGs like CH4 and CO2.
基金supported partly by National Natural Science Foundation of China (Grant No. 11071045)Shanghai Leading Academic Discipline Project (Grant No. B210)
文摘This paper considers variable selection for moment restriction models. We propose a penalized empirical likelihood (PEL) approach that has desirable asymptotic properties comparable to the penalized likelihood approach, which relies on a correct parametric likelihood specification. In addition to being consistent and having the oracle property, PEL admits inference on parameter without having to estimate its estimator's covariance. An approximate algorithm, along with a consistent BIC-type criterion for selecting the tuning parameters, is provided for FEL. The proposed algorithm enjoys considerable computational efficiency and overcomes the drawback of the local quadratic approximation of nonconcave penalties. Simulation studies to evaluate and compare the performances of our method with those of the existing ones show that PEL is competitive and robust. The proposed method is illustrated with two real examples.
基金Project supported by the Joint Funds of the National Natural Science Foundation of China(No.U1509214)the Beijing Natural Science Foundation,China(No.4174105)+1 种基金the Key Projects of National Bureau of Statistics of China(No.2017LZ05)the Discipline Construction Foundation of the Central University of Finance and Economics,China(No.2016XX02)
文摘Feature selection is an important approach to dimensionality reduction in the field of text classification. Because of the difficulty in handling the problem that the selected features always contain redundant information, we propose a new simple feature selection method, which can effectively filter the redundant features. First, to calculate the relationship between two words, the definitions of word frequency based relevance and correlative redundancy are introduced. Furthermore, an optimal feature selection(OFS) method is chosen to obtain a feature subset FS1. Finally, to improve the execution speed, the redundant features in FS1 are filtered by combining a predetermined threshold, and the filtered features are memorized in the linked lists. Experiments are carried out on three datasets(Web KB, 20-Newsgroups, and Reuters-21578) where in support vector machines and na?ve Bayes are used. The results show that the classification accuracy of the proposed method is generally higher than that of typical traditional methods(information gain, improved Gini index, and improved comprehensively measured feature selection) and the OFS methods. Moreover, the proposed method runs faster than typical mutual information-based methods(improved and normalized mutual information-based feature selections, and multilabel feature selection based on maximum dependency and minimum redundancy) while simultaneously ensuring classification accuracy. Statistical results validate the effectiveness of the proposed method in handling redundant information in text classification.