One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific object...One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific objectives,measurement targets,and measurement requirements for the proposed Gas and Ion Analyzer(GIA).The GIA is designed for in-situ mass spectrometry of neutral gases and low-energy ions,such as hydrogen,carbon,and oxygen,in the vicinity of 311P.Ion sampling techniques are essential for the GIA's Time-of-Flight(TOF)mass analysis capabilities.In this paper,we present an enhanced ion sampling technique through the development of an ion attraction model and an ion source model.The ion attraction model demonstrates that adjusting attraction grid voltage can enhance the detection efficiency of low-energy ions and mitigate the repulsive force of ions during sampling,which is influenced by the satellite's surface positive charging.The ion source model simulates the processes of gas ionization and ion multiplication.Simulation results indicate that the GIA can achieve a lower pressure limit below 10-13Pa and possess a dynamic range exceeding 10~9.These performances ensure the generation of ions with stable and consistent current,which is crucial for high-resolution and broad dynamic range mass spectrometer analysis.Preliminary testing experiments have verified GIA's capability to detect gas compositions such as H2O and N2.In-situ measurements near 311P using GIA are expected to significantly contribute to our understanding of asteroid activity mechanisms,the evolution of the atmospheric and ionized environments of main-belt comets,the interactions with solar wind,and the origin of Earth's water.展开更多
Aiming at the problems of difficulty in balancing construction efficiency and quality,as well as the high safety risks of working at heights during the construction of main piers for highway bridges,this study takes a...Aiming at the problems of difficulty in balancing construction efficiency and quality,as well as the high safety risks of working at heights during the construction of main piers for highway bridges,this study takes a specific bridge project as an example to introduce the technology of hydraulically sliding formwork for the construction of main piers of highway bridges.An in-depth analysis of the project’s construction process found that this technology can effectively improve construction efficiency,ensure the quality of concrete pouring,and significantly reduce the potential safety hazards of working at heights.It provides a reliable technical solution for constructing the main piers of highway bridges and has important reference significance for similar projects.展开更多
The Early Eocene Sui Main Limestone(SML)reservoirs in the Qadirpur area are significant hydrocarbon-producing formations but suffer from low permeability and poor reservoir characteristics that lead to well abandonmen...The Early Eocene Sui Main Limestone(SML)reservoirs in the Qadirpur area are significant hydrocarbon-producing formations but suffer from low permeability and poor reservoir characteristics that lead to well abandonment.Although commonly used,conventional stimulation techniques such as hydraulic fracturing and acidizing pose environmental risks,high costs,and sensitivity to fluctuations in crude oil prices.Meanwhile,cryogenic liquid nitrogen(LN2)treatment has emerged as an innovative,eco-friendly alternative due to its thermal shock effects,which enhance rock permeability and porosity.Herein,SML core samples are treated with LN2 for 30,60,and 90 min to obtain samples designated as SML_30,SML_60,and SML_90,respectively.These are examined using X-ray diffraction(XRD),atomic force microscopy(AFM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),nanoindentation,and petrophysical measurements to evaluate the changes in their petrophysical,morphological,and micromechanical properties.The post-treatment analysis reveals that LN2 cooling effectively induces micro-cracks,with fracture widths of up to 40μm,along with a substantial increase in surface roughness from 350 to 942 nm.Additionally,micromechanical analysis indicates notable changes in the indentation modulus due to stress-induced alterations in the rock matrix.At optimal LN2 exposure(90 min),the porosity and permeability of the SML sample is more than doubled.These findings provide valuable insights into LN2-induced reservoir enhancements,thereby contributing to a better understanding of fluid flow behavior and hydrocarbon recovery in tight gas reservoirs.Thus,LN2 treatment presents a promising,cost-effective,and environmentally sustainable alternative to conventional stimulation methods.展开更多
In the paper,copepod universal formulas are applied to construct a copepod individual-based model(IBM),and a genetic algorithm(GA)is incorporated in the formulas with genes as species parameters.The IBM initially cons...In the paper,copepod universal formulas are applied to construct a copepod individual-based model(IBM),and a genetic algorithm(GA)is incorporated in the formulas with genes as species parameters.The IBM initially constructs the individuals with all possible genes similar to the original state of natural selection.Climate-averaged temperature and chlorophyll a(Chl a)time series at the surface layer of fixed points in the Georges Bank(GB)and the Gulf of Maine(GOM)are taken as the model environment.The IBM has been running for 50 a in the environment without inter-annual change.The IBM results indicate that some of the life history traits of the top ten abundant species output by the IBM in the GB and the GOM are consistent with the real species Calanus finmarchicus,Pseudocalanus spp.,Centropages typicus,and Centropages hamatus in terms of reproduction strategy,time to reach the maximum abundance,water temperature preference,and adult body mass.The study of the top ten abundant species with multidimensional scaling(MDS)and clustering analysis(CA)methods indicates that reproduction strategy is the basis for grouping.For the species taking the broadcasting strategy,both GB and GOM environments tend to choose smallbodied species with cold-water preference,such as Pseudocalanus spp.;for the species taking the egg-carrying strategies,the GB environment selects large-bodied species with cold-water preference,such as C.finmarchicus,while the GOM environment selects medium-bodied species with warm-water preference,such as Centropages spp.(C.typicus and C.hamatus).After gene mutation is added to the IBM,the model result gets simple,which needs to be further improved.The significance of the paper lies in systematically studying the impact of GB and GOM environments on the evolutionary life history traits of copepods for the first time.展开更多
This paper focuses on the research of the main transformer selection and layout scheme for new energy step-up substations.From the perspective of engineering design,it analyzes the principles of main transformer selec...This paper focuses on the research of the main transformer selection and layout scheme for new energy step-up substations.From the perspective of engineering design,it analyzes the principles of main transformer selection,key parameters,and their matching with the characteristics of new energy.It also explores the layout methods and optimization strategies.Combined with typical case studies,optimization suggestions are proposed for the design of main transformers in new energy step-up substations.The research shows that rational main transformer selection and scientific layout schemes can better adapt to the characteristics of new energy projects while effectively improving land use efficiency and economic viability.This study can provide technical experience support for the design of new energy projects.展开更多
In 2004 and 2014,two monographs on hypobaric storage(LP)were published by Stanley P.Burg.Based on his theoretical framework and technological advancements,as well as the research and development of equipment conducted...In 2004 and 2014,two monographs on hypobaric storage(LP)were published by Stanley P.Burg.Based on his theoretical framework and technological advancements,as well as the research and development of equipment conducted under his guidance,alongside customer practices and reflections on various scientific literature both domestically and internationally,it is posited that,as articulated in the monograph,misconceptions regarding his theory and technology in Western scientific literature prior to 1985 continue to persist.This ongoing dissemination of misunderstandings has resulted in a near stagnation of research and has adversely impacted the Chinese academic community as well.Consequently,it is essential to delineate the characteristics and main points of its theory and technology,with the aim of offering guidance to individuals seeking to comprehend its foundational purpose.LP technology is a dynamic physical technology that continuously and uninterruptedly extracts air from a closed container and simultaneously introduces fresh,low-pressure moist air from the external environment,while maintaining specific levels of humidity and/or temperature within the container and upholding a predetermined pressure value.Preservation technology is the collective term for the set of various technical parameters associated with preservation,including pressure,relative humidity,and other relevant factors,to which LP equipment is specifically designed.The theory of LP is characterized by the enhanced diffusion of gases and vapors that enter and exit the commodity in a dynamic manner under low pressure conditions.The theoretical points involve equipment performance,low pressure,the impact of trace concentrations of gases such as O_(2),CO_(2) and C_(2)H_(4) that naturally occur at low pressure,diffusive mass transfer,heat transfer,and impacts on the activity of enzymes associated with maturation and senescence.The technology is characterized by dynamic low pressure,and the range of commodities preserved is comparable to that of refrigeration.However,certain commodities exiting the hypobaric environment possess subsequent preservation advantages that are not available through refrigeration.The main points of the technology encompass an extended sotrage life,a postponement of quality degradation,minimized water loss,the suppression of pathogen growth,and the killing of both internal and external insects of the commodity under dynamic low pressure conditions.The core advantage of LP technology lies in its ability to significantly reduce water loss,inhibit respiration and C_(2)H_(4) action,and pathogen growth,killing insects and modulate the activity of enzymes associated with maturation and senescence in post-harvest fresh horticultural products.Consequently,this technology plays a crucial role in prolonging the post-harvest lifespan of these commodities and mitigating quality degradation.Over the past decade,researchers in China have developed a hypobaric short period treatment technology,grounded in LP theory and technical practice,which is commonly referred to as hypobaric treatment.This method has garnered significant attention,leading to an increase in both domestic and international research.A growing body of literature categorizes LP as hypobaric treatment,while some studies also consider vacuum packaging and modified atmosphere packaging(MAP)as LP or hypobaric treatment.Misunderstandings are exacerbated by confusion surrounding nomenclature,which,in conjunction with pre-existing misconceptions,represents a significant barrier to both the research and practical application of the technology.The successful commercial implementation of a vacuum cold fresh chain,centered on LP or hypobaric treatment technology,may be the sole solution to the prevailing misunderstandings associated with LP.展开更多
Based on the data of drilling,logging,experiment and gas testing in the Nanchuan area,southeastern Sichuan Basin,the hydrocarbon generation potential,gas genesis,occurrence state,migration,preservation conditions,pore...Based on the data of drilling,logging,experiment and gas testing in the Nanchuan area,southeastern Sichuan Basin,the hydrocarbon generation potential,gas genesis,occurrence state,migration,preservation conditions,pore and fracture features and accumulation evolution of the first member of Permian Maokou Formation(Mao 1 Member)are systematically studied,and the main controlling factors of unconventional gas enrichment and high production in marlstone assemblage of Mao 1 Member are discussed.(1)The enrichment and high yield of unconventional natural gas in the Mao 1 Member are controlled by three factors:carbon-rich fabric controlling hydrocarbon generation potential,good preservation controlling enrichment,and natural fracture controlling production.(2)The carbonate rocks of Mao 1 Member with carbon rich fabric have significant gas potential,exhibiting characteristics of self-generation and self-storage,which lays the material foundation for natural gas accumulation.(3)The occurrence state of natural gas is mainly free gas,which is prone to lateral migration,and good storage conditions are the key to natural gas enrichment.Positive structure is more conducive to natural gas accumulation,and a good compartment is created jointly by the self-sealing property of the Mao 1 Member and its top and bottom sealing property in monoclinal area,which is favorable for gas accumulation by retention.(4)Natural fractures are the main reservoir space and flow channel,and the more developed natural fractures are,the more conducive to the formation of high-quality porous-fractured reservoirs and the accumulation of natural gas,which is the core of controlling production.(5)The accumulation model of unconventional natural gas is proposed as“self-generation and self-storage,preservation controlling richness,and fractures controlling production”.(6)Identifying fracture development areas with good preservation conditions is the key to successful exploration,and implementing horizontal well staged acidizing and fracturing is an important means to increase production and efficiency.The study results are of referential significance for further understanding the natural gas enrichment in the Mao 1 Member and guiding the efficient exploration and development of new types of unconventional natural gas.展开更多
[Objective] This study aimed to explore the related mechanisms of the breaking of flue-cured tobacco leaves. [Method] Anti-breaking models of the main veins of flue-cured tobacco leaves were constructed for principal ...[Objective] This study aimed to explore the related mechanisms of the breaking of flue-cured tobacco leaves. [Method] Anti-breaking models of the main veins of flue-cured tobacco leaves were constructed for principal component analysis on the anti-breaking index, leaf traits and cellulose contents. [Result] The results showed that the growth traits had certain relevance with the cellulose contents while the leaf weight assumed a significant negative correlation with the anti-breaking index, indicating that the heavier the leaf weight was, the weaker the anti-breaking capacity of flue-cured tobacco would be; the cross-sectional area of main veins and the cellulose contents had shown a positive correlation with the anti-breaking index, indicating that the thicker the main vein of flue-cured tobacco was, the higher the cellulose contents would be, and the stronger the anti-breaking capacity of flue-cured tobacco leaves would be. [Conclusion] This study provided theoretical basis and reference to improve tobacco production and enhance the quality of flue-cured tobacco.展开更多
Using 3 sterile lines and 12 restorer of glutinous sorghum as experimental materials,36 hybrid combinations（3×12 NCⅡ） were designed to analyze the combining ability and heritability of six main agronomic trait...Using 3 sterile lines and 12 restorer of glutinous sorghum as experimental materials,36 hybrid combinations（3×12 NCⅡ） were designed to analyze the combining ability and heritability of six main agronomic traits,including plant height,panicle length,growth period,1 000-grain weight,per panicle grains and per panicle grain weight.The results showed that except per panicle grain number all other five agronomic traits have remarkable or extremely remarkable general combining ability and specific combining ability.Six agronomic traits were found to be control by additive genetic effect.Most of these agronomic traits are more easily influenced by restorers than sterile lines,suggesting that more attention should be paid to select restores in hybrid glutinous sorghum breeding.The narrow-sense heritability of these agronomic traits were in order growth period plant height per panicle grain weight panicle length 1 000-grain weight per panicle grains.展开更多
Based on the engineering background of the Jiangxinzhou Bridge in Nanjing, issues related to the spatial main saddle of the self-anchored suspension bridge are studied. The refinement finite element model is establish...Based on the engineering background of the Jiangxinzhou Bridge in Nanjing, issues related to the spatial main saddle of the self-anchored suspension bridge are studied. The refinement finite element model is established by the secondary development technology based on the platform of the general finite element program, and a reasonable load pattern is used in its spatial structural analysis, by which its path of force transference and stress distribution are obtained. Matched with the spatial main cable, the tangency point correction method is also discussed. The results show that the lateral wall stress of the saddle groove is higher than the stress within the wall due to the role of lateral forces in the finished bridge state; the horizontal volume force of the main cable can generate a gradient distributed vertical extrusion pressure on the saddle clamping device and the main saddle body; the geometric nonlinear effect of the self- anchored suspension bridge cable system in the construction process is significant, which can be reflected in the spatial tangent point position of the main cable with the main saddle changes a lot from free cable to finished cable.展开更多
The present status of self-elevating drilling units was analysed. Based on statistics of the main dimensions of self-elevating drilling units, a mathematical model was established using stepwise return procedures and ...The present status of self-elevating drilling units was analysed. Based on statistics of the main dimensions of self-elevating drilling units, a mathematical model was established using stepwise return procedures and a back-propagation neural network. mathematical model is applicable and reliable. The of the main dimensions of self-elevating drilling Analysis of examples of calculations showed that the model is useful for mastering the essential variations units and can be used for technical and economic analysis as well as in conceptual designs of drilling units.展开更多
[Objective] The aim was to investigate the genetic diversity of the main commercial varieties of Brassica napus in Guizhou Province at the molecular level. [Method] Nine main commercial rapeseed cultivars in Guizhou w...[Objective] The aim was to investigate the genetic diversity of the main commercial varieties of Brassica napus in Guizhou Province at the molecular level. [Method] Nine main commercial rapeseed cultivars in Guizhou were detected by 40 pairs of SSR primers used in the national regional trial of B. napus, and then clus-tering analysis was carried out. [Result] A total of 191 bands were amplified, and 143 （accounting for 75%） of them showed polymorphism among the nine rapeseed cultivars. By cluster analysis, the nine cultivars were divided into two groups. Group A included seven varieties, and group B consisted of two cultivars from Guizhou In-stitute of Oil Crops. The cultivars in group A were further divided into sub-groups A1 and A2 at the similarity coefficient of 0.643 4. Sub-group A1 included three culti-vars from Guizhou Rapeseed Institute, and sub-group A2 included the other four cultivars from Guizhou Institute of Oil Crops. [Conclusion] The cultivars bred by the same institute had similar genetic background. The cultivars from Guizhou Institute of Oil Crops showed wider genetic basis. However, the genetic similarity coefficient between Qianyou 17 and Qianyou 29 was up to 0.87, suggesting that they shared closer genetic basis.展开更多
To discover the knowledge of fault diagnosis in maintenance record of flexible manufacture system(FMS) equipment. An algorithm (process) was presented, which consists of ① preparatory phase in which some items in mai...To discover the knowledge of fault diagnosis in maintenance record of flexible manufacture system(FMS) equipment. An algorithm (process) was presented, which consists of ① preparatory phase in which some items in maintenance record are selected and decomposed into associated concepts and attributes, and ② discovering and establishing process, in which some possible relationships between the concepts and attributes can be established and knowledge is formulated. The rich diagnosis knowledge in maintenance record was captured through applying the method. An application of the method to the diagnosis system for FMS equipment showed that the approach is correct and effective.展开更多
This paper analyzes the applications of four air terminal device（ATD）models（i.e.,the basic model,the box model,the N-point momentum model,the jet main region specification model）in computational fluid dynamics（CF...This paper analyzes the applications of four air terminal device（ATD）models（i.e.,the basic model,the box model,the N-point momentum model,the jet main region specification model）in computational fluid dynamics（CFD）simulation and their performance in case study.A full-scale experiment is performed in an environment chamber,and the measured air velocity and temperature fields are compared with the simulation results by using four ATD models.The velocity and temperature fields are measured by an omni-directional thermo-anemometer system.It demonstrates that the basic model and the box model are not applicable to complicated air terminal devices.At the occupant area,the relative errors between simulated and measured air velocities are less than 20% based on the N-point momentum model and the jet main region specification model.Around the ATD zone,the relative error between the numerical and measured air velocity based on the jet main region specification model is less than 15%.The jet main region specification model is proved to be an applicable approach and a more accurate way to study the airflow pattern around the ATD with complicated geometry.展开更多
With the aid of commercial finite element analysis software package ANSYS,investigations are made on the contributions of main components to stiffness of the main module for parallel machine tools,and it is found that...With the aid of commercial finite element analysis software package ANSYS,investigations are made on the contributions of main components to stiffness of the main module for parallel machine tools,and it is found that the frame is the main contributor.Then,influences of constraints,strut length and working ways of the main module have also been investigated.It can be concluded that when one of the main planes of the frame without linear drive unit is constrained,the largest whole stiffness can be acquired.And,the stiffness is much better when the main module is used in a vertical machine tool instead of a horizontal one.Finally,the principle of stiffness variation is summarized when the mobile platform reaches various positions within its working space and when various loads are applied.These achievements have provided critical instructions for the design of the main module for parallel machine tools.展开更多
"Days of the Butterfly"was one of Alice Munro's short stories written in 1950 s, when she was still a new hand. This paper will mainly focus on the development of the main characters in the story, includ..."Days of the Butterfly"was one of Alice Munro's short stories written in 1950 s, when she was still a new hand. This paper will mainly focus on the development of the main characters in the story, including Myra, the black girl who was the heroine, the teacher Miss Darling, and the Narrator"I". In portraying these characters, Munro adopted several writing techniques including conversation, detailed description, psychological description and so on. She vividly transferred those characters into paper.展开更多
基金Supported by the National Natural Science Foundation of China(42474239,41204128)China National Space Administration(Pre-research project on Civil Aerospace Technologies No.D010301)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA17010303)。
文摘One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific objectives,measurement targets,and measurement requirements for the proposed Gas and Ion Analyzer(GIA).The GIA is designed for in-situ mass spectrometry of neutral gases and low-energy ions,such as hydrogen,carbon,and oxygen,in the vicinity of 311P.Ion sampling techniques are essential for the GIA's Time-of-Flight(TOF)mass analysis capabilities.In this paper,we present an enhanced ion sampling technique through the development of an ion attraction model and an ion source model.The ion attraction model demonstrates that adjusting attraction grid voltage can enhance the detection efficiency of low-energy ions and mitigate the repulsive force of ions during sampling,which is influenced by the satellite's surface positive charging.The ion source model simulates the processes of gas ionization and ion multiplication.Simulation results indicate that the GIA can achieve a lower pressure limit below 10-13Pa and possess a dynamic range exceeding 10~9.These performances ensure the generation of ions with stable and consistent current,which is crucial for high-resolution and broad dynamic range mass spectrometer analysis.Preliminary testing experiments have verified GIA's capability to detect gas compositions such as H2O and N2.In-situ measurements near 311P using GIA are expected to significantly contribute to our understanding of asteroid activity mechanisms,the evolution of the atmospheric and ionized environments of main-belt comets,the interactions with solar wind,and the origin of Earth's water.
文摘Aiming at the problems of difficulty in balancing construction efficiency and quality,as well as the high safety risks of working at heights during the construction of main piers for highway bridges,this study takes a specific bridge project as an example to introduce the technology of hydraulically sliding formwork for the construction of main piers of highway bridges.An in-depth analysis of the project’s construction process found that this technology can effectively improve construction efficiency,ensure the quality of concrete pouring,and significantly reduce the potential safety hazards of working at heights.It provides a reliable technical solution for constructing the main piers of highway bridges and has important reference significance for similar projects.
文摘The Early Eocene Sui Main Limestone(SML)reservoirs in the Qadirpur area are significant hydrocarbon-producing formations but suffer from low permeability and poor reservoir characteristics that lead to well abandonment.Although commonly used,conventional stimulation techniques such as hydraulic fracturing and acidizing pose environmental risks,high costs,and sensitivity to fluctuations in crude oil prices.Meanwhile,cryogenic liquid nitrogen(LN2)treatment has emerged as an innovative,eco-friendly alternative due to its thermal shock effects,which enhance rock permeability and porosity.Herein,SML core samples are treated with LN2 for 30,60,and 90 min to obtain samples designated as SML_30,SML_60,and SML_90,respectively.These are examined using X-ray diffraction(XRD),atomic force microscopy(AFM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),nanoindentation,and petrophysical measurements to evaluate the changes in their petrophysical,morphological,and micromechanical properties.The post-treatment analysis reveals that LN2 cooling effectively induces micro-cracks,with fracture widths of up to 40μm,along with a substantial increase in surface roughness from 350 to 942 nm.Additionally,micromechanical analysis indicates notable changes in the indentation modulus due to stress-induced alterations in the rock matrix.At optimal LN2 exposure(90 min),the porosity and permeability of the SML sample is more than doubled.These findings provide valuable insights into LN2-induced reservoir enhancements,thereby contributing to a better understanding of fluid flow behavior and hydrocarbon recovery in tight gas reservoirs.Thus,LN2 treatment presents a promising,cost-effective,and environmentally sustainable alternative to conventional stimulation methods.
基金The National Natural Science Foundation of China Project under contract No.42206150the Technology Development Program of Shanghai Ocean University under contract No.A2-2006-20-200207.
文摘In the paper,copepod universal formulas are applied to construct a copepod individual-based model(IBM),and a genetic algorithm(GA)is incorporated in the formulas with genes as species parameters.The IBM initially constructs the individuals with all possible genes similar to the original state of natural selection.Climate-averaged temperature and chlorophyll a(Chl a)time series at the surface layer of fixed points in the Georges Bank(GB)and the Gulf of Maine(GOM)are taken as the model environment.The IBM has been running for 50 a in the environment without inter-annual change.The IBM results indicate that some of the life history traits of the top ten abundant species output by the IBM in the GB and the GOM are consistent with the real species Calanus finmarchicus,Pseudocalanus spp.,Centropages typicus,and Centropages hamatus in terms of reproduction strategy,time to reach the maximum abundance,water temperature preference,and adult body mass.The study of the top ten abundant species with multidimensional scaling(MDS)and clustering analysis(CA)methods indicates that reproduction strategy is the basis for grouping.For the species taking the broadcasting strategy,both GB and GOM environments tend to choose smallbodied species with cold-water preference,such as Pseudocalanus spp.;for the species taking the egg-carrying strategies,the GB environment selects large-bodied species with cold-water preference,such as C.finmarchicus,while the GOM environment selects medium-bodied species with warm-water preference,such as Centropages spp.(C.typicus and C.hamatus).After gene mutation is added to the IBM,the model result gets simple,which needs to be further improved.The significance of the paper lies in systematically studying the impact of GB and GOM environments on the evolutionary life history traits of copepods for the first time.
文摘This paper focuses on the research of the main transformer selection and layout scheme for new energy step-up substations.From the perspective of engineering design,it analyzes the principles of main transformer selection,key parameters,and their matching with the characteristics of new energy.It also explores the layout methods and optimization strategies.Combined with typical case studies,optimization suggestions are proposed for the design of main transformers in new energy step-up substations.The research shows that rational main transformer selection and scientific layout schemes can better adapt to the characteristics of new energy projects while effectively improving land use efficiency and economic viability.This study can provide technical experience support for the design of new energy projects.
文摘In 2004 and 2014,two monographs on hypobaric storage(LP)were published by Stanley P.Burg.Based on his theoretical framework and technological advancements,as well as the research and development of equipment conducted under his guidance,alongside customer practices and reflections on various scientific literature both domestically and internationally,it is posited that,as articulated in the monograph,misconceptions regarding his theory and technology in Western scientific literature prior to 1985 continue to persist.This ongoing dissemination of misunderstandings has resulted in a near stagnation of research and has adversely impacted the Chinese academic community as well.Consequently,it is essential to delineate the characteristics and main points of its theory and technology,with the aim of offering guidance to individuals seeking to comprehend its foundational purpose.LP technology is a dynamic physical technology that continuously and uninterruptedly extracts air from a closed container and simultaneously introduces fresh,low-pressure moist air from the external environment,while maintaining specific levels of humidity and/or temperature within the container and upholding a predetermined pressure value.Preservation technology is the collective term for the set of various technical parameters associated with preservation,including pressure,relative humidity,and other relevant factors,to which LP equipment is specifically designed.The theory of LP is characterized by the enhanced diffusion of gases and vapors that enter and exit the commodity in a dynamic manner under low pressure conditions.The theoretical points involve equipment performance,low pressure,the impact of trace concentrations of gases such as O_(2),CO_(2) and C_(2)H_(4) that naturally occur at low pressure,diffusive mass transfer,heat transfer,and impacts on the activity of enzymes associated with maturation and senescence.The technology is characterized by dynamic low pressure,and the range of commodities preserved is comparable to that of refrigeration.However,certain commodities exiting the hypobaric environment possess subsequent preservation advantages that are not available through refrigeration.The main points of the technology encompass an extended sotrage life,a postponement of quality degradation,minimized water loss,the suppression of pathogen growth,and the killing of both internal and external insects of the commodity under dynamic low pressure conditions.The core advantage of LP technology lies in its ability to significantly reduce water loss,inhibit respiration and C_(2)H_(4) action,and pathogen growth,killing insects and modulate the activity of enzymes associated with maturation and senescence in post-harvest fresh horticultural products.Consequently,this technology plays a crucial role in prolonging the post-harvest lifespan of these commodities and mitigating quality degradation.Over the past decade,researchers in China have developed a hypobaric short period treatment technology,grounded in LP theory and technical practice,which is commonly referred to as hypobaric treatment.This method has garnered significant attention,leading to an increase in both domestic and international research.A growing body of literature categorizes LP as hypobaric treatment,while some studies also consider vacuum packaging and modified atmosphere packaging(MAP)as LP or hypobaric treatment.Misunderstandings are exacerbated by confusion surrounding nomenclature,which,in conjunction with pre-existing misconceptions,represents a significant barrier to both the research and practical application of the technology.The successful commercial implementation of a vacuum cold fresh chain,centered on LP or hypobaric treatment technology,may be the sole solution to the prevailing misunderstandings associated with LP.
基金Supported by the National Science and Technology Major Project of China(2016ZX05061)Sinopec Science and Technology Department Project(P21042-4,P25030)。
文摘Based on the data of drilling,logging,experiment and gas testing in the Nanchuan area,southeastern Sichuan Basin,the hydrocarbon generation potential,gas genesis,occurrence state,migration,preservation conditions,pore and fracture features and accumulation evolution of the first member of Permian Maokou Formation(Mao 1 Member)are systematically studied,and the main controlling factors of unconventional gas enrichment and high production in marlstone assemblage of Mao 1 Member are discussed.(1)The enrichment and high yield of unconventional natural gas in the Mao 1 Member are controlled by three factors:carbon-rich fabric controlling hydrocarbon generation potential,good preservation controlling enrichment,and natural fracture controlling production.(2)The carbonate rocks of Mao 1 Member with carbon rich fabric have significant gas potential,exhibiting characteristics of self-generation and self-storage,which lays the material foundation for natural gas accumulation.(3)The occurrence state of natural gas is mainly free gas,which is prone to lateral migration,and good storage conditions are the key to natural gas enrichment.Positive structure is more conducive to natural gas accumulation,and a good compartment is created jointly by the self-sealing property of the Mao 1 Member and its top and bottom sealing property in monoclinal area,which is favorable for gas accumulation by retention.(4)Natural fractures are the main reservoir space and flow channel,and the more developed natural fractures are,the more conducive to the formation of high-quality porous-fractured reservoirs and the accumulation of natural gas,which is the core of controlling production.(5)The accumulation model of unconventional natural gas is proposed as“self-generation and self-storage,preservation controlling richness,and fractures controlling production”.(6)Identifying fracture development areas with good preservation conditions is the key to successful exploration,and implementing horizontal well staged acidizing and fracturing is an important means to increase production and efficiency.The study results are of referential significance for further understanding the natural gas enrichment in the Mao 1 Member and guiding the efficient exploration and development of new types of unconventional natural gas.
基金Supported by the Fund of Anhui Provincial Tobacco Monopoly Bureau(AHKJ2008-03)Anhui Provincial University Key Project of Natural Science(KJ2010A114)Undergraduate Student Science and Technology Innovation Fund of Anhui Agricultural University(2010233)~~
文摘[Objective] This study aimed to explore the related mechanisms of the breaking of flue-cured tobacco leaves. [Method] Anti-breaking models of the main veins of flue-cured tobacco leaves were constructed for principal component analysis on the anti-breaking index, leaf traits and cellulose contents. [Result] The results showed that the growth traits had certain relevance with the cellulose contents while the leaf weight assumed a significant negative correlation with the anti-breaking index, indicating that the heavier the leaf weight was, the weaker the anti-breaking capacity of flue-cured tobacco would be; the cross-sectional area of main veins and the cellulose contents had shown a positive correlation with the anti-breaking index, indicating that the thicker the main vein of flue-cured tobacco was, the higher the cellulose contents would be, and the stronger the anti-breaking capacity of flue-cured tobacco leaves would be. [Conclusion] This study provided theoretical basis and reference to improve tobacco production and enhance the quality of flue-cured tobacco.
基金Supported by National Sorghum Industry Technology Development System(CARS-06-01-05)Financial Genetic Breeding Program of Sichuan Province(2011JYGC11-031)+2 种基金Key R&D Program for Sorghum Breeding of Sichuan Province during the 12th Five Year PeriodScience&Technology Pillar Program in Sichuan ProvinceYouth Funds of Sichuan Academy of Agricultural Sciences(2012QNJJ-023)~~
文摘Using 3 sterile lines and 12 restorer of glutinous sorghum as experimental materials,36 hybrid combinations（3×12 NCⅡ） were designed to analyze the combining ability and heritability of six main agronomic traits,including plant height,panicle length,growth period,1 000-grain weight,per panicle grains and per panicle grain weight.The results showed that except per panicle grain number all other five agronomic traits have remarkable or extremely remarkable general combining ability and specific combining ability.Six agronomic traits were found to be control by additive genetic effect.Most of these agronomic traits are more easily influenced by restorers than sterile lines,suggesting that more attention should be paid to select restores in hybrid glutinous sorghum breeding.The narrow-sense heritability of these agronomic traits were in order growth period plant height per panicle grain weight panicle length 1 000-grain weight per panicle grains.
基金The National High Technology Research and Development Program of China(863 Program)(No.2006AA04Z416)the National Science Fund for Distinguished Young Scholars(No.50725828)
文摘Based on the engineering background of the Jiangxinzhou Bridge in Nanjing, issues related to the spatial main saddle of the self-anchored suspension bridge are studied. The refinement finite element model is established by the secondary development technology based on the platform of the general finite element program, and a reasonable load pattern is used in its spatial structural analysis, by which its path of force transference and stress distribution are obtained. Matched with the spatial main cable, the tangency point correction method is also discussed. The results show that the lateral wall stress of the saddle groove is higher than the stress within the wall due to the role of lateral forces in the finished bridge state; the horizontal volume force of the main cable can generate a gradient distributed vertical extrusion pressure on the saddle clamping device and the main saddle body; the geometric nonlinear effect of the self- anchored suspension bridge cable system in the construction process is significant, which can be reflected in the spatial tangent point position of the main cable with the main saddle changes a lot from free cable to finished cable.
基金Supported by the National 863 Plan Foundation under Grant No.2003AA414060
文摘The present status of self-elevating drilling units was analysed. Based on statistics of the main dimensions of self-elevating drilling units, a mathematical model was established using stepwise return procedures and a back-propagation neural network. mathematical model is applicable and reliable. The of the main dimensions of self-elevating drilling Analysis of examples of calculations showed that the model is useful for mastering the essential variations units and can be used for technical and economic analysis as well as in conceptual designs of drilling units.
基金Supported by Special Fund for Seed Breeding from Guizhou Provincial Agricultural Committee[(2012)026]Agricultural Science and Technology Research Program of Department of Science and Technology of Guizhou Province[(2013)3003]+1 种基金Agricultural Science and Technology Research Program of Department of Science and Technology of Guizhou Province[(2013)3088]a grant from the Central Authorities of China for Supporting Local Platform Construction[(2011)4001]~~
文摘[Objective] The aim was to investigate the genetic diversity of the main commercial varieties of Brassica napus in Guizhou Province at the molecular level. [Method] Nine main commercial rapeseed cultivars in Guizhou were detected by 40 pairs of SSR primers used in the national regional trial of B. napus, and then clus-tering analysis was carried out. [Result] A total of 191 bands were amplified, and 143 （accounting for 75%） of them showed polymorphism among the nine rapeseed cultivars. By cluster analysis, the nine cultivars were divided into two groups. Group A included seven varieties, and group B consisted of two cultivars from Guizhou In-stitute of Oil Crops. The cultivars in group A were further divided into sub-groups A1 and A2 at the similarity coefficient of 0.643 4. Sub-group A1 included three culti-vars from Guizhou Rapeseed Institute, and sub-group A2 included the other four cultivars from Guizhou Institute of Oil Crops. [Conclusion] The cultivars bred by the same institute had similar genetic background. The cultivars from Guizhou Institute of Oil Crops showed wider genetic basis. However, the genetic similarity coefficient between Qianyou 17 and Qianyou 29 was up to 0.87, suggesting that they shared closer genetic basis.
文摘To discover the knowledge of fault diagnosis in maintenance record of flexible manufacture system(FMS) equipment. An algorithm (process) was presented, which consists of ① preparatory phase in which some items in maintenance record are selected and decomposed into associated concepts and attributes, and ② discovering and establishing process, in which some possible relationships between the concepts and attributes can be established and knowledge is formulated. The rich diagnosis knowledge in maintenance record was captured through applying the method. An application of the method to the diagnosis system for FMS equipment showed that the approach is correct and effective.
文摘This paper analyzes the applications of four air terminal device（ATD）models（i.e.,the basic model,the box model,the N-point momentum model,the jet main region specification model）in computational fluid dynamics（CFD）simulation and their performance in case study.A full-scale experiment is performed in an environment chamber,and the measured air velocity and temperature fields are compared with the simulation results by using four ATD models.The velocity and temperature fields are measured by an omni-directional thermo-anemometer system.It demonstrates that the basic model and the box model are not applicable to complicated air terminal devices.At the occupant area,the relative errors between simulated and measured air velocities are less than 20% based on the N-point momentum model and the jet main region specification model.Around the ATD zone,the relative error between the numerical and measured air velocity based on the jet main region specification model is less than 15%.The jet main region specification model is proved to be an applicable approach and a more accurate way to study the airflow pattern around the ATD with complicated geometry.
文摘With the aid of commercial finite element analysis software package ANSYS,investigations are made on the contributions of main components to stiffness of the main module for parallel machine tools,and it is found that the frame is the main contributor.Then,influences of constraints,strut length and working ways of the main module have also been investigated.It can be concluded that when one of the main planes of the frame without linear drive unit is constrained,the largest whole stiffness can be acquired.And,the stiffness is much better when the main module is used in a vertical machine tool instead of a horizontal one.Finally,the principle of stiffness variation is summarized when the mobile platform reaches various positions within its working space and when various loads are applied.These achievements have provided critical instructions for the design of the main module for parallel machine tools.
文摘"Days of the Butterfly"was one of Alice Munro's short stories written in 1950 s, when she was still a new hand. This paper will mainly focus on the development of the main characters in the story, including Myra, the black girl who was the heroine, the teacher Miss Darling, and the Narrator"I". In portraying these characters, Munro adopted several writing techniques including conversation, detailed description, psychological description and so on. She vividly transferred those characters into paper.
