Solar arrays are important and indispensable parts of spacecraft and provide energy support for spacecraft to operate in orbit and complete on-orbit missions.When a spacecraft is in orbit,because the solar array is ex...Solar arrays are important and indispensable parts of spacecraft and provide energy support for spacecraft to operate in orbit and complete on-orbit missions.When a spacecraft is in orbit,because the solar array is exposed to the harsh space environment,with increasing working time,the performance of its internal electronic components gradually degrade until abnormal damage occurs.This damage makes solar array power generation unable to fully meet the energy demand of a spacecraft.Therefore,timely and accurate detection of solar array anomalies is of great significance for the on-orbit operation and maintenance management of spacecraft.In this paper,we propose an anomaly detection method for spacecraft solar arrays based on the integrated least squares support vector machine(ILS-SVM)model:it selects correlated telemetry data from spacecraft solar arrays to form a training set and extracts n groups of training subsets from this set,then gets n corresponding least squares support vector machine(LS-SVM)submodels by training on these training subsets,respectively;after that,the ILS-SVM model is obtained by integrating these submodels through a weighting operation to increase the prediction accuracy and so on;finally,based on the obtained ILS-SVM model,a parameterfree and unsupervised anomaly determination method is proposed to detect the health status of solar arrays.We use the telemetry data set from a satellite in orbit to carry out experimental verification and find that the proposed method can diagnose solar array anomalies in time and can capture the signs before a solar array anomaly occurs,which reflects the applicability of the method.展开更多
Using the twin shear stress yield criterion, the surface integral of the co-line vectors, and the integration depending on upper limit, Kobayashi's three-dimensional velocity field of rolling was analyzed and an anal...Using the twin shear stress yield criterion, the surface integral of the co-line vectors, and the integration depending on upper limit, Kobayashi's three-dimensional velocity field of rolling was analyzed and an analytical expression of rolling torque and single force was obtained. Through redoing the same experiment of rolling pure lead as Sims, the calculated results by the above expression were compared with those of Kobayashi and Sims formulae. The results show that the twin shear stress yield criterion is available for rolling analysis and the calculated results by the new formula are a little higher than those by Kobayashi and Sims ones if the reduction ratio is less than 30%.展开更多
The recombinant Saccharomyces cerevisiae strain stably expressing recombinant human glucagon-like peptide-l(rhGLP-1) analogue, as a potential oral drug delivery system for diabetes type II treatment, was successfull...The recombinant Saccharomyces cerevisiae strain stably expressing recombinant human glucagon-like peptide-l(rhGLP-1) analogue, as a potential oral drug delivery system for diabetes type II treatment, was successfully constructed by the homologous recombination between chromosomal DNA and yeast and integrating vector pNK-GLP containing yeast ribosomal DNA fragments. The amount of rhGLP-I analogue fusion protein in transformant SG2 reached ca. 0.84 mg per gram of packed cells when SG2 was grown for 24 h in the YPD medium with a inoculum and medium ratio of 1:1. Oral administration of 5 g lyophilized SG2/kg to hyperglycemic rats decreased serum glucose from (24.8±1.40) to (21.2±1.36) mmol/L.展开更多
We introduce a novel approach to multifractal data in order to achieve transcended modeling and forecasting performances by extracting time series out of local Hurst exponent calculations at a specified scale.First,th...We introduce a novel approach to multifractal data in order to achieve transcended modeling and forecasting performances by extracting time series out of local Hurst exponent calculations at a specified scale.First,the long range and co-movement dependencies of the time series are scrutinized on time-frequency space using multiple wavelet coherence analysis.Then,the multifractal behaviors of the series are verified by multifractal de-trended fluctuation analysis and its local Hurst exponents are calculated.Additionally,root mean squares of residuals at the specified scale are procured from an intermediate step during local Hurst exponent calculations.These internally calculated series have been used to estimate the process with vector autoregressive fractionally integrated moving average(VARFIMA)model and forecasted accordingly.In our study,the daily prices of gold,silver and platinum are used for assessment.The results have shown that all metals do behave in phase movement on long term periods and possess multifractal features.Furthermore,the intermediate time series obtained during local Hurst exponent calculations still appertain the co-movement as well as multifractal characteristics of the raw data and may be successfully re-scaled,modeled and forecasted by using VARFIMA model.Conclusively,VARFIMA model have notably surpassed its univariate counterpart(ARFIMA)in all efficacious trials while re-emphasizing the importance of comovement procurement in modeling.Our study’s novelty lies in using a multifractal de-trended fluctuation analysis,along with multiple wavelet coherence analysis,for forecasting purposes to an extent not seen before.The results will be of particular significance to finance researchers and practitioners.展开更多
Theoretical calculation and experimental results for a polarizer with sinusoidal grooves used in the electron cyclotron resonance heating (ECRH) system of the HL-2A tokamak are presented. The calculation is based on...Theoretical calculation and experimental results for a polarizer with sinusoidal grooves used in the electron cyclotron resonance heating (ECRH) system of the HL-2A tokamak are presented. The calculation is based on an integral method developed in the vector theory of diffraction gratings, and the polarization characteristics obtained with a low-power test are in good agreement with the numerical calculated results. With the polarizer assembled in a miter bend in the ECRH transmission line, pure ordinary mode (O-mode) and extraordinary mode (X-mode) polarized waves are also expected in the high-power experiment, depending on the polarizer rotation angle and the toroidal injection angle of the electron cyclotron (EC) wave beam. Second-harmonic X-mode experiments were successfully explored in HL-2A. Experimental result revealed that the electron temperature increased from 0.8 keV (Ohmic heating phase) to 1.5 keV (second X-mode heating phase).展开更多
The important notions and results of the integral invariants of Poincard and Cartan-Poincard and the relationship between integral invariant and invariant form established first by E. Cartan in the classical mechanics...The important notions and results of the integral invariants of Poincard and Cartan-Poincard and the relationship between integral invariant and invariant form established first by E. Cartan in the classical mechanics are generalized to Hamilton mechanics on Kiihler manifold, by the theory of modern geometry and advanced calculus, to get the corresponding wider arid deeper results. differential展开更多
A layered architecture of muhisensory integration gripper system is first developed, which includes data acquisition layer, data processing layer and network interface layer. Then we propose a novel support-vector-mac...A layered architecture of muhisensory integration gripper system is first developed, which includes data acquisition layer, data processing layer and network interface layer. Then we propose a novel support-vector-machine-based data fusion algorithm and also design the gripper system by combining data fusion with CAN bus and CORBA technology, which provides the gripper system with outstanding characteristics such as modularization and intelligence. A multisensory integration gripper test bed is finally built on which a circuit board replacement job based on Internet-based teleoperation is achieved. The experimental results verify the validity of this gripper system design.展开更多
This paper investigates the stability problem for sampled-data systems by adopting a refined semi-looped-functional,which is with the following two improvements.Firstly,the new functional term is with a new integral v...This paper investigates the stability problem for sampled-data systems by adopting a refined semi-looped-functional,which is with the following two improvements.Firstly,the new functional term is with a new integral vectorη0,which contains sampling information of the systems and associates two commonly used vectors.Secondly,the vectorη0 is combined into various zero equations for processing the functional,especially where a new equation is derived fromη0.Based on the refined functional,further stability results for sampled-data systems are obtained.And the effectiveness of the results is numerically verified through two examples at the end.展开更多
Background:Drylands,which are among the biosphere's most naturally limiting and environmentally variable ecosystems,constitute three-quarters of the African continent.As a result,environmental sustainability and h...Background:Drylands,which are among the biosphere's most naturally limiting and environmentally variable ecosystems,constitute three-quarters of the African continent.As a result,environmental sustainability and human development along with vector-borne disease(VBD)control historically have been especially challenging in Africa,particularly in the sub-Saharan and Sahelian drylands.Here,the VBD burden,food insecurity,environmental degradation,and social vulnerability are particularly severe.Changing climate can exacerbate the legion of environmental health threats in Africa,the social dimensions of which are now part of the international development agenda.Accordingly,the need to better understand the dynamics and complex coupling of populations and environments as exemplified by drylands is increasingly recognized as critical to the design of more sustainable interventions.Main body:This scoping review examines the challenge of vector-borne disease control in drylands with a focus on Africa,and the dramatic,ongoing environmental and social changes taking place.Dryland societies persisted and even flourished in the past despite changing climates,extreme and unpredictable weather,and marginal conditions for agriculture.Yet intrusive forces largely out of the control of traditional dryland societies,along with the negative impacts of globalization,have contributed to the erosion of dryland's cultural and natural resources.This has led to the loss of resilience underlying the adaptive capacity formerly widely exhibited among dryland societies.A growing body of evidence from studies of environmental and natural resource management demonstrates how,in light of dryland system's inherent complexity,these factors and top-down interventions can impede sustainable development and vector-borne disease control.Strengthening adaptive capacity through community-based,participatory methods that build on local knowledge and are tailored to local ecological conditions,hold the best promise of reversing current trends.Conclusions:A significant opportunity exists to simultaneously address the increasing threat of vector-borne diseases and climate change through methods aimed at strengthening adaptive capacity.The integrative framework and methods based on social-ecological systems and resilience theory offers a novel set of tools that allow multiple threats and sources of vulnerability to be addressed in combination.Integration of recent advances in vector borne disease ecology and wider deployment of these tools could help reverse the negative social and environmental trends currently seen in African drylands.展开更多
Background:The control of vector-borne diseases(VBD)is one of the greatest challenges on the global health agenda.Rapid and uncontrolled urbanization has heightened the interest in addressing these challenges through ...Background:The control of vector-borne diseases(VBD)is one of the greatest challenges on the global health agenda.Rapid and uncontrolled urbanization has heightened the interest in addressing these challenges through an integrated vector management(IVM)approach.The aim was to identify components related to impacts,economic evaluation,and sustainability that might contribute to this integrated approach to VBD prevention.Main body:We conducted a scoping review of available literature(2000-2016)using PubMed,Web of Science,Cochrane,CINAHL,Econlit,LILACS,Global Health Database,Scopus,and Embase,as well as Tropical Diseases Bulletin,WHOLIS,WHO Pesticide Evaluation Scheme,and Google Scholar.MeSH terms and free-text terms were used.A data extraction form was used,including TIDieR and ASTAIRE.MMAT and CHEERS were used to evaluate quality.Of the 42 documents reviewed,30 were focused on dengue,eight on malaria,and two on leishmaniasis.More than a half of the studies were conducted in the Americas.Half used a quantitative descriptive approach(n=21),followed by cluster randomized controlled trials(n=11).Regarding impacts,outcomes were:a)use of measures for vector control;b)vector control;c)health measures;and d)social measures.IVM reduced breeding sites,the entomology index,and parasite rates.Results were heterogeneous,with variable magnitudes,but in all cases were favourable to the intervention.Evidence of IVM impacts on health outcomes was very limited but showed reduced incidence.Social outcomes were improved abilities and capacities,empowerment,and community knowledge.Regarding economic evaluation,only four studies performed an economic analysis,and intervention benefits outweighed costs.Costeffectiveness was dependent on illness incidence.The results provided key elements to analyze sustainability in terms of three dimensions(social,economic,and environmental),emphasizing the implementation of a community-focused eco-bio-social approach.Conclusions:IVM has an impact on reducing vector breeding sites and the entomology index,but evidence of impacts on health outcomes is limited.Social outcomes are improved abilities and capacities,empowerment,and community knowledge.Economic evaluations are scarce,and cost-effectiveness is dependent on illness incidence.Community capacity building is the main component of sustainability,together with collaboration,institutionalization,and routinization of activities.Findings indicate a great heterogeneity in the interventions and highlight the need for characterizing interventions rigorously to facilitate transferability.展开更多
To promote spinosad biosynthesis by improving the limited oxygen supply during high-density fermentation of Saccharopolyspora spinosa, the open reading frame of the Vitreoscilla hemoglobin gene was placed under the co...To promote spinosad biosynthesis by improving the limited oxygen supply during high-density fermentation of Saccharopolyspora spinosa, the open reading frame of the Vitreoscilla hemoglobin gene was placed under the control of the promoter for the erythromycin resistance gene by splicing using overlapping extension PCR. This was cloned into the integrating vector pSET152, yielding the Vitreoscilla hemoglobin gene expression plasmid pSET152EVHB. This was then introduced into S. spinosa SP06081 by conjugal transfer, and integrated into the chromosome by site-specific recombination at the integration site ФC31 on pSET152EVHB. The resultant conjugant, S. spinosa S078-1101, was genetically stable. The integration was further confirmed by PCR and Southern blotting analysis. A carbon monoxide differential spectrum assay showed that active Vitreoscilla hemoglobin was successfully expressed in S. spinosa S078-1101. Fermentation results revealed that expression of the Vitreoscilla hemoglobin gene significantly promoted spinosad biosynthesis under normal oxygen and moderately oxygen-limiting conditions (P〈0.01). These findings demonstrate that integrating expression of the Vitreoscilla hemoglobin gene improves oxygen uptake and is an effective means for the genetic improvement of S. spinosa fermentation. Saccharopolyspora spinosa, spinosad, Vitreoscilla hemoglobin, integrating vector, homologous recombination展开更多
This paper presents a multiple target implementation technique for a doubly fed induction generator (DFIG) under unbalanced and distorted grid voltage based on direct power control (DPC). Based on the mathematical...This paper presents a multiple target implementation technique for a doubly fed induction generator (DFIG) under unbalanced and distorted grid voltage based on direct power control (DPC). Based on the mathematical model of DFIG under unbalanced and distorted voltage, the proportional and integral (PI) regulator is adopted to regulate the DFIG average active and reactive powers, while the vector P1 (VPI) resonant regulator is used to achieve three alternative control targets: (1) balanced and sinusoidal stator current; (2) smooth instantaneous stator active and reactive powers; (3) smooth electromagnetic torque and instantaneous stator reactive power. The major advantage of the proposed control strategy over the conventional method is that neither negative and harmonic sequence decomposition of grid voltage nor complicated control reference calculation is required. The insensitivity of the proposed control strategy to DFIG parameter deviation is analyzed. Finally, the DFIG experimental system is developed to validate the availability of the proposed DPC strategy under unbalanced and distorted grid voltage,展开更多
基金supported by the National Natural Science Foundation of China(7190121061973310).
文摘Solar arrays are important and indispensable parts of spacecraft and provide energy support for spacecraft to operate in orbit and complete on-orbit missions.When a spacecraft is in orbit,because the solar array is exposed to the harsh space environment,with increasing working time,the performance of its internal electronic components gradually degrade until abnormal damage occurs.This damage makes solar array power generation unable to fully meet the energy demand of a spacecraft.Therefore,timely and accurate detection of solar array anomalies is of great significance for the on-orbit operation and maintenance management of spacecraft.In this paper,we propose an anomaly detection method for spacecraft solar arrays based on the integrated least squares support vector machine(ILS-SVM)model:it selects correlated telemetry data from spacecraft solar arrays to form a training set and extracts n groups of training subsets from this set,then gets n corresponding least squares support vector machine(LS-SVM)submodels by training on these training subsets,respectively;after that,the ILS-SVM model is obtained by integrating these submodels through a weighting operation to increase the prediction accuracy and so on;finally,based on the obtained ILS-SVM model,a parameterfree and unsupervised anomaly determination method is proposed to detect the health status of solar arrays.We use the telemetry data set from a satellite in orbit to carry out experimental verification and find that the proposed method can diagnose solar array anomalies in time and can capture the signs before a solar array anomaly occurs,which reflects the applicability of the method.
基金ItemSponsored by National Natural Science Foundation of China (50474015)
文摘Using the twin shear stress yield criterion, the surface integral of the co-line vectors, and the integration depending on upper limit, Kobayashi's three-dimensional velocity field of rolling was analyzed and an analytical expression of rolling torque and single force was obtained. Through redoing the same experiment of rolling pure lead as Sims, the calculated results by the above expression were compared with those of Kobayashi and Sims formulae. The results show that the twin shear stress yield criterion is available for rolling analysis and the calculated results by the new formula are a little higher than those by Kobayashi and Sims ones if the reduction ratio is less than 30%.
文摘The recombinant Saccharomyces cerevisiae strain stably expressing recombinant human glucagon-like peptide-l(rhGLP-1) analogue, as a potential oral drug delivery system for diabetes type II treatment, was successfully constructed by the homologous recombination between chromosomal DNA and yeast and integrating vector pNK-GLP containing yeast ribosomal DNA fragments. The amount of rhGLP-I analogue fusion protein in transformant SG2 reached ca. 0.84 mg per gram of packed cells when SG2 was grown for 24 h in the YPD medium with a inoculum and medium ratio of 1:1. Oral administration of 5 g lyophilized SG2/kg to hyperglycemic rats decreased serum glucose from (24.8±1.40) to (21.2±1.36) mmol/L.
文摘We introduce a novel approach to multifractal data in order to achieve transcended modeling and forecasting performances by extracting time series out of local Hurst exponent calculations at a specified scale.First,the long range and co-movement dependencies of the time series are scrutinized on time-frequency space using multiple wavelet coherence analysis.Then,the multifractal behaviors of the series are verified by multifractal de-trended fluctuation analysis and its local Hurst exponents are calculated.Additionally,root mean squares of residuals at the specified scale are procured from an intermediate step during local Hurst exponent calculations.These internally calculated series have been used to estimate the process with vector autoregressive fractionally integrated moving average(VARFIMA)model and forecasted accordingly.In our study,the daily prices of gold,silver and platinum are used for assessment.The results have shown that all metals do behave in phase movement on long term periods and possess multifractal features.Furthermore,the intermediate time series obtained during local Hurst exponent calculations still appertain the co-movement as well as multifractal characteristics of the raw data and may be successfully re-scaled,modeled and forecasted by using VARFIMA model.Conclusively,VARFIMA model have notably surpassed its univariate counterpart(ARFIMA)in all efficacious trials while re-emphasizing the importance of comovement procurement in modeling.Our study’s novelty lies in using a multifractal de-trended fluctuation analysis,along with multiple wavelet coherence analysis,for forecasting purposes to an extent not seen before.The results will be of particular significance to finance researchers and practitioners.
文摘Theoretical calculation and experimental results for a polarizer with sinusoidal grooves used in the electron cyclotron resonance heating (ECRH) system of the HL-2A tokamak are presented. The calculation is based on an integral method developed in the vector theory of diffraction gratings, and the polarization characteristics obtained with a low-power test are in good agreement with the numerical calculated results. With the polarizer assembled in a miter bend in the ECRH transmission line, pure ordinary mode (O-mode) and extraordinary mode (X-mode) polarized waves are also expected in the high-power experiment, depending on the polarizer rotation angle and the toroidal injection angle of the electron cyclotron (EC) wave beam. Second-harmonic X-mode experiments were successfully explored in HL-2A. Experimental result revealed that the electron temperature increased from 0.8 keV (Ohmic heating phase) to 1.5 keV (second X-mode heating phase).
文摘The important notions and results of the integral invariants of Poincard and Cartan-Poincard and the relationship between integral invariant and invariant form established first by E. Cartan in the classical mechanics are generalized to Hamilton mechanics on Kiihler manifold, by the theory of modern geometry and advanced calculus, to get the corresponding wider arid deeper results. differential
文摘A layered architecture of muhisensory integration gripper system is first developed, which includes data acquisition layer, data processing layer and network interface layer. Then we propose a novel support-vector-machine-based data fusion algorithm and also design the gripper system by combining data fusion with CAN bus and CORBA technology, which provides the gripper system with outstanding characteristics such as modularization and intelligence. A multisensory integration gripper test bed is finally built on which a circuit board replacement job based on Internet-based teleoperation is achieved. The experimental results verify the validity of this gripper system design.
基金supported in part by the National Natural Science Foundation of China under Grant Nos.62221004 and 62073166the Shandong Provincial Natural Science Foundation under Grant No.ZR2021ZD13+1 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province under Grant No.KYCX230473the Project on the Technological Leading Talent Teams Led by Frontiers Science Center for Complex Equipment System Dynamics under Grant No.FSCCESD220401。
文摘This paper investigates the stability problem for sampled-data systems by adopting a refined semi-looped-functional,which is with the following two improvements.Firstly,the new functional term is with a new integral vectorη0,which contains sampling information of the systems and associates two commonly used vectors.Secondly,the vectorη0 is combined into various zero equations for processing the functional,especially where a new equation is derived fromη0.Based on the refined functional,further stability results for sampled-data systems are obtained.And the effectiveness of the results is numerically verified through two examples at the end.
文摘Background:Drylands,which are among the biosphere's most naturally limiting and environmentally variable ecosystems,constitute three-quarters of the African continent.As a result,environmental sustainability and human development along with vector-borne disease(VBD)control historically have been especially challenging in Africa,particularly in the sub-Saharan and Sahelian drylands.Here,the VBD burden,food insecurity,environmental degradation,and social vulnerability are particularly severe.Changing climate can exacerbate the legion of environmental health threats in Africa,the social dimensions of which are now part of the international development agenda.Accordingly,the need to better understand the dynamics and complex coupling of populations and environments as exemplified by drylands is increasingly recognized as critical to the design of more sustainable interventions.Main body:This scoping review examines the challenge of vector-borne disease control in drylands with a focus on Africa,and the dramatic,ongoing environmental and social changes taking place.Dryland societies persisted and even flourished in the past despite changing climates,extreme and unpredictable weather,and marginal conditions for agriculture.Yet intrusive forces largely out of the control of traditional dryland societies,along with the negative impacts of globalization,have contributed to the erosion of dryland's cultural and natural resources.This has led to the loss of resilience underlying the adaptive capacity formerly widely exhibited among dryland societies.A growing body of evidence from studies of environmental and natural resource management demonstrates how,in light of dryland system's inherent complexity,these factors and top-down interventions can impede sustainable development and vector-borne disease control.Strengthening adaptive capacity through community-based,participatory methods that build on local knowledge and are tailored to local ecological conditions,hold the best promise of reversing current trends.Conclusions:A significant opportunity exists to simultaneously address the increasing threat of vector-borne diseases and climate change through methods aimed at strengthening adaptive capacity.The integrative framework and methods based on social-ecological systems and resilience theory offers a novel set of tools that allow multiple threats and sources of vulnerability to be addressed in combination.Integration of recent advances in vector borne disease ecology and wider deployment of these tools could help reverse the negative social and environmental trends currently seen in African drylands.
文摘Background:The control of vector-borne diseases(VBD)is one of the greatest challenges on the global health agenda.Rapid and uncontrolled urbanization has heightened the interest in addressing these challenges through an integrated vector management(IVM)approach.The aim was to identify components related to impacts,economic evaluation,and sustainability that might contribute to this integrated approach to VBD prevention.Main body:We conducted a scoping review of available literature(2000-2016)using PubMed,Web of Science,Cochrane,CINAHL,Econlit,LILACS,Global Health Database,Scopus,and Embase,as well as Tropical Diseases Bulletin,WHOLIS,WHO Pesticide Evaluation Scheme,and Google Scholar.MeSH terms and free-text terms were used.A data extraction form was used,including TIDieR and ASTAIRE.MMAT and CHEERS were used to evaluate quality.Of the 42 documents reviewed,30 were focused on dengue,eight on malaria,and two on leishmaniasis.More than a half of the studies were conducted in the Americas.Half used a quantitative descriptive approach(n=21),followed by cluster randomized controlled trials(n=11).Regarding impacts,outcomes were:a)use of measures for vector control;b)vector control;c)health measures;and d)social measures.IVM reduced breeding sites,the entomology index,and parasite rates.Results were heterogeneous,with variable magnitudes,but in all cases were favourable to the intervention.Evidence of IVM impacts on health outcomes was very limited but showed reduced incidence.Social outcomes were improved abilities and capacities,empowerment,and community knowledge.Regarding economic evaluation,only four studies performed an economic analysis,and intervention benefits outweighed costs.Costeffectiveness was dependent on illness incidence.The results provided key elements to analyze sustainability in terms of three dimensions(social,economic,and environmental),emphasizing the implementation of a community-focused eco-bio-social approach.Conclusions:IVM has an impact on reducing vector breeding sites and the entomology index,but evidence of impacts on health outcomes is limited.Social outcomes are improved abilities and capacities,empowerment,and community knowledge.Economic evaluations are scarce,and cost-effectiveness is dependent on illness incidence.Community capacity building is the main component of sustainability,together with collaboration,institutionalization,and routinization of activities.Findings indicate a great heterogeneity in the interventions and highlight the need for characterizing interventions rigorously to facilitate transferability.
基金supported by the National Basic Research Program of China (Grant Nos. 2012CB722301 and 2011CB111605)the National High Technology Research and Development Project of China (Grant No. 2011AA10A203)the National Natural Science Foundation of China (Grant No. 31070006)
文摘To promote spinosad biosynthesis by improving the limited oxygen supply during high-density fermentation of Saccharopolyspora spinosa, the open reading frame of the Vitreoscilla hemoglobin gene was placed under the control of the promoter for the erythromycin resistance gene by splicing using overlapping extension PCR. This was cloned into the integrating vector pSET152, yielding the Vitreoscilla hemoglobin gene expression plasmid pSET152EVHB. This was then introduced into S. spinosa SP06081 by conjugal transfer, and integrated into the chromosome by site-specific recombination at the integration site ФC31 on pSET152EVHB. The resultant conjugant, S. spinosa S078-1101, was genetically stable. The integration was further confirmed by PCR and Southern blotting analysis. A carbon monoxide differential spectrum assay showed that active Vitreoscilla hemoglobin was successfully expressed in S. spinosa S078-1101. Fermentation results revealed that expression of the Vitreoscilla hemoglobin gene significantly promoted spinosad biosynthesis under normal oxygen and moderately oxygen-limiting conditions (P〈0.01). These findings demonstrate that integrating expression of the Vitreoscilla hemoglobin gene improves oxygen uptake and is an effective means for the genetic improvement of S. spinosa fermentation. Saccharopolyspora spinosa, spinosad, Vitreoscilla hemoglobin, integrating vector, homologous recombination
基金Project supported by the National High-Tech R&D Program(863)of China(No.2011AA050204)the National Natural Science Foundation of China(No.51277159)
文摘This paper presents a multiple target implementation technique for a doubly fed induction generator (DFIG) under unbalanced and distorted grid voltage based on direct power control (DPC). Based on the mathematical model of DFIG under unbalanced and distorted voltage, the proportional and integral (PI) regulator is adopted to regulate the DFIG average active and reactive powers, while the vector P1 (VPI) resonant regulator is used to achieve three alternative control targets: (1) balanced and sinusoidal stator current; (2) smooth instantaneous stator active and reactive powers; (3) smooth electromagnetic torque and instantaneous stator reactive power. The major advantage of the proposed control strategy over the conventional method is that neither negative and harmonic sequence decomposition of grid voltage nor complicated control reference calculation is required. The insensitivity of the proposed control strategy to DFIG parameter deviation is analyzed. Finally, the DFIG experimental system is developed to validate the availability of the proposed DPC strategy under unbalanced and distorted grid voltage,