After introducing some of the basic definitions and results from the theory of groupoid and Lie algebroid,we investigate the discrete Lagrangian mechanics from the viewpoint of groupoid theory and give the connection ...After introducing some of the basic definitions and results from the theory of groupoid and Lie algebroid,we investigate the discrete Lagrangian mechanics from the viewpoint of groupoid theory and give the connection betweengroupoids variation and the methods of the first and second discrete variational principles.展开更多
We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China ...We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass, and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June, and the biomass of cyanobacteria reached a maximum in August. From February to March 2012, the main form of M. aeruginosa was the single-cell form; M. aeruginosa colonies began to appear from April, and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July, and then gradually decreased from August. The diameter range ofM. aeruginosa colonies was 18.37-237.77μm, and most of the colonies were distributed in the range 20-200μm, comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobaeterial growth was in the range of 15-30℃. In natural water bodies, photosynthetically active radiation had a significant positive influence on the colonial diameter of M. aeruginosa （P〈0.01）.展开更多
As one of the most important steps in the design of bearing-less rotor systems,the design of flexible beam has received much research attention.Because of the very complex working environment of helicopter,the flexibl...As one of the most important steps in the design of bearing-less rotor systems,the design of flexible beam has received much research attention.Because of the very complex working environment of helicopter,the flexible beam should satisfy both the strength and dynamic requirements.However,traditional optimization research focused only on either the strength or dynamical characteristics.To sufficiently improve the performance of the flexible beam,both aspects must be considered.This paper proposes a two-stage optimization method based on the Hamilton variational principle:Variational asymptotic beam section analysis(VABS)program and genetic algorithm(GA).Consequently,a two-part analysis model based on the Hamilton variational principle and VABS is established to calculate section characteristics and structural dynamics characteristics,respectively.Subsequently,the two parts are combined to establish a two-stage optimization process and search with GA to obtain the best dynamic characteristics combinations.Based on the primary optimization results,the section characteristics of the flexible beam are further optimized using GA.The optimization results show that the torsional stiffness decreases by 36.1%compared with the full 0°laying scheme without optimization and the dynamic requirements are achieved.The natural frequencies of flapping and torsion meet the requirements(0.5 away from the passing frequencies of the blade,0.25 away from the excitation force frequency,and the flapping and torsion frequencies keep a corresponding distance).The results indicate that the optimization method can significantly improve the performance of the flexible beam.展开更多
Literature continues to generate controversies as to what it is and what it is for. That is one of the reasons for the proliferation of ＂literary theories.＂ The notion is here placed between quotation marks because ...Literature continues to generate controversies as to what it is and what it is for. That is one of the reasons for the proliferation of ＂literary theories.＂ The notion is here placed between quotation marks because it does not mean the same thing to all the scholars in the field. Some regard it in the same way that theory functions in the sciences, where it focuses on the object it is associated with. For example, the atomic theory of matter is concerned with the internal constitution or the characterizing properties of matter. Others, however, are looking beyond the object towards the reader and the extra-textual environment. The approaches to literary studies which look beyond the individual work to outside phenomena are many and increasing all the time as new issues and concerns arrive on the social scene. Issues of climate change are fairly topical now; and criticism is already responding with such ideas as eco-criticism. The question of the identity of the literary object has to be kept in the front burner, so that it is not swamped by the many different interests which attach to literature from time to time. Bringing attention back to the literary work is the central concern of this paper; and we are doing this by way of the metaphors of perception often used with respect to the literary work as these suggest that the work is something to focus on, rather than to see through to something else. Finally, I elaborate the concept of integrity as an appurtenance of the literary text that attracts and holds the gaze.展开更多
The cGAS-MITA pathway of cytosolic DNA sensing plays essential roles in immune response against pathogens that contain DNA or with DNA production in their life cycles. The cGAS-MITA pathway also detects leaked or aber...The cGAS-MITA pathway of cytosolic DNA sensing plays essential roles in immune response against pathogens that contain DNA or with DNA production in their life cycles. The cGAS-MITA pathway also detects leaked or aberrant accumulated self DNA in the cytoplasm under certain pathological conditions, such as virus induced cell death, DNA damage, mitochondria damage, gene mutations, which results in autoimmune diseases. Therefore, the cGAS-MITA pathway must be tightly controlled to ensure proper immune response against pathogens and to avoid autoimmune diseases. The regulation of cGAS-MITA pathway at MITA-level have been extensively explored and reviewed elsewhere,here we provide a summary and perspective on recent advances in understanding of the cGAS regulation.展开更多
The last two to three decades have seen significant advances in the mechanics of unsaturated soils.It is now widely recognized that the fundamental principles in soil mechanics must cover both saturated and unsaturate...The last two to three decades have seen significant advances in the mechanics of unsaturated soils.It is now widely recognized that the fundamental principles in soil mechanics must cover both saturated and unsaturated soils.Nevertheless,there is still a great deal of uncertainties in the geotechnical community about how soil mechanics principles well-established for saturated soils can be extended to unsaturated soils.There is even wide skepticism about the necessity of such extension in engineering practice.This paper discusses some common pitfalls related to the fundamental principles that govern the volume change,shear strength and hydromechanical behaviour of unsaturated soils.It also attempts to address the issue of engineering relevance of unsaturated soil mechanics.展开更多
This paper investigates the theoretical aspects for an optimal harvesting problem of a nonlinear size-structured population model in a periodic environment. We establish the well-posedness of the state system by means...This paper investigates the theoretical aspects for an optimal harvesting problem of a nonlinear size-structured population model in a periodic environment. We establish the well-posedness of the state system by means of frozen coefficients and fixed point reasoning. The existence of a unique optimal policy is proved via Ekeland＇s variational principle, and the first-order optimality conditions are derived by a suitable normM cone and a dual system. The results obtained would be beneficial for exploration of renewable展开更多
基金National Key Basic Research Project of China under Grant No.2004CB318000National Natural Science Foundation of China under Grant Nos.10375038 and 90403018
文摘After introducing some of the basic definitions and results from the theory of groupoid and Lie algebroid,we investigate the discrete Lagrangian mechanics from the viewpoint of groupoid theory and give the connection betweengroupoids variation and the methods of the first and second discrete variational principles.
基金Supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China(Nos.2012ZX07103-005-01,2012ZX07103-004-02)the National Natural Science Foundation of China(Nos.41171366,41471075)the Science Foundation of Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No.NIGLAS2012135013)
文摘We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass, and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June, and the biomass of cyanobacteria reached a maximum in August. From February to March 2012, the main form of M. aeruginosa was the single-cell form; M. aeruginosa colonies began to appear from April, and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July, and then gradually decreased from August. The diameter range ofM. aeruginosa colonies was 18.37-237.77μm, and most of the colonies were distributed in the range 20-200μm, comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobaeterial growth was in the range of 15-30℃. In natural water bodies, photosynthetically active radiation had a significant positive influence on the colonial diameter of M. aeruginosa （P〈0.01）.
基金supported by the Foundation of National Key Laboratory of Rotorcraft Aeromechanics,Nanjing University of Aeronautics and Astronautics(No.614222004030917)。
文摘As one of the most important steps in the design of bearing-less rotor systems,the design of flexible beam has received much research attention.Because of the very complex working environment of helicopter,the flexible beam should satisfy both the strength and dynamic requirements.However,traditional optimization research focused only on either the strength or dynamical characteristics.To sufficiently improve the performance of the flexible beam,both aspects must be considered.This paper proposes a two-stage optimization method based on the Hamilton variational principle:Variational asymptotic beam section analysis(VABS)program and genetic algorithm(GA).Consequently,a two-part analysis model based on the Hamilton variational principle and VABS is established to calculate section characteristics and structural dynamics characteristics,respectively.Subsequently,the two parts are combined to establish a two-stage optimization process and search with GA to obtain the best dynamic characteristics combinations.Based on the primary optimization results,the section characteristics of the flexible beam are further optimized using GA.The optimization results show that the torsional stiffness decreases by 36.1%compared with the full 0°laying scheme without optimization and the dynamic requirements are achieved.The natural frequencies of flapping and torsion meet the requirements(0.5 away from the passing frequencies of the blade,0.25 away from the excitation force frequency,and the flapping and torsion frequencies keep a corresponding distance).The results indicate that the optimization method can significantly improve the performance of the flexible beam.
文摘Literature continues to generate controversies as to what it is and what it is for. That is one of the reasons for the proliferation of ＂literary theories.＂ The notion is here placed between quotation marks because it does not mean the same thing to all the scholars in the field. Some regard it in the same way that theory functions in the sciences, where it focuses on the object it is associated with. For example, the atomic theory of matter is concerned with the internal constitution or the characterizing properties of matter. Others, however, are looking beyond the object towards the reader and the extra-textual environment. The approaches to literary studies which look beyond the individual work to outside phenomena are many and increasing all the time as new issues and concerns arrive on the social scene. Issues of climate change are fairly topical now; and criticism is already responding with such ideas as eco-criticism. The question of the identity of the literary object has to be kept in the front burner, so that it is not swamped by the many different interests which attach to literature from time to time. Bringing attention back to the literary work is the central concern of this paper; and we are doing this by way of the metaphors of perception often used with respect to the literary work as these suggest that the work is something to focus on, rather than to see through to something else. Finally, I elaborate the concept of integrity as an appurtenance of the literary text that attracts and holds the gaze.
基金supported by the National Natural Science Foundation of China (31400742)
文摘The cGAS-MITA pathway of cytosolic DNA sensing plays essential roles in immune response against pathogens that contain DNA or with DNA production in their life cycles. The cGAS-MITA pathway also detects leaked or aberrant accumulated self DNA in the cytoplasm under certain pathological conditions, such as virus induced cell death, DNA damage, mitochondria damage, gene mutations, which results in autoimmune diseases. Therefore, the cGAS-MITA pathway must be tightly controlled to ensure proper immune response against pathogens and to avoid autoimmune diseases. The regulation of cGAS-MITA pathway at MITA-level have been extensively explored and reviewed elsewhere,here we provide a summary and perspective on recent advances in understanding of the cGAS regulation.
基金supported by the National Natural Science Foundation of China(Grant No.51208519)
文摘The last two to three decades have seen significant advances in the mechanics of unsaturated soils.It is now widely recognized that the fundamental principles in soil mechanics must cover both saturated and unsaturated soils.Nevertheless,there is still a great deal of uncertainties in the geotechnical community about how soil mechanics principles well-established for saturated soils can be extended to unsaturated soils.There is even wide skepticism about the necessity of such extension in engineering practice.This paper discusses some common pitfalls related to the fundamental principles that govern the volume change,shear strength and hydromechanical behaviour of unsaturated soils.It also attempts to address the issue of engineering relevance of unsaturated soil mechanics.
文摘This paper investigates the theoretical aspects for an optimal harvesting problem of a nonlinear size-structured population model in a periodic environment. We establish the well-posedness of the state system by means of frozen coefficients and fixed point reasoning. The existence of a unique optimal policy is proved via Ekeland＇s variational principle, and the first-order optimality conditions are derived by a suitable normM cone and a dual system. The results obtained would be beneficial for exploration of renewable
