期刊文献+
共找到11,945篇文章
< 1 2 250 >
每页显示 20 50 100
Perception of fundamental science to boost lithium metal anodes toward practical application
1
作者 Jinkun Wang Li Wang +2 位作者 Hong Xu Li Sheng Xiangming He 《Green Energy & Environment》 SCIE EI CAS CSCD 2024年第3期454-472,共19页
As a key material for lithium metal batteries(LMBs),lithium metal is one of the most promising anode materials to break the bottleneck of battery energy density and a commonly used active material for reference electr... As a key material for lithium metal batteries(LMBs),lithium metal is one of the most promising anode materials to break the bottleneck of battery energy density and a commonly used active material for reference electrodes.Although lithium anodes are regarded as the holy grail of lithium batteries,decades of exploration have not led to the successful commercialization of LMBs,due mainly to the challenges related to the inherent properties of lithium metal.To pave the way for further investigation,herein,a comprehensive review focusing on the fundamental science of lithium are provided.Firstly,the natures of lithium atoms and their isotopes,lithium clusters and lithium crystals are revisited,especially their structural and energetic properties.Subsequently,the electrochemical properties of lithium metal are reviewed.Numerous important concepts and scientific questions,including the electronic structure of lithium,influence of high pressure and low temperature on the properties of lithium,factors influencing lithium deposition,generation of lithium dendrites,and electrode potential of lithium in different electrolytes,are explained and analyzed in detail.Approaches to improve the performance of lithium anodes and thoughtfulness about the electrode potential in lithium battery research are proposed. 展开更多
关键词 LITHIUM CLUSTER Crystal Physicochemical property fundamental science
下载PDF
New Approach to Synchronize General Relativity and Quantum Mechanics with Constant “K”-Resulting Dark Matter as a New Fundamental Force Particle
2
作者 Siva Prasad Kodukula 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期292-302,共11页
Planck scale plays a vital role in describing fundamental forces. Space time describes strength of fundamental force. In this paper, Einstein’s general relativity equation has been described in terms of contraction a... Planck scale plays a vital role in describing fundamental forces. Space time describes strength of fundamental force. In this paper, Einstein’s general relativity equation has been described in terms of contraction and expansion forces of space time. According to this, the space time with Planck diameter is a flat space time. This is the only diameter of space time that can be used as signal transformation in special relativity. This space time diameter defines the fundamental force which belongs to that space time. In quantum mechanics, this space time diameter is only the quantum of space which belongs to that particular fundamental force. Einstein’s general relativity equation and Planck parameters of quantum mechanics have been written in terms of equations containing a constant “K”, thus found a new equation for transformation of general relativity space time in to quantum space time. In this process of synchronization, there is a possibility of a new fundamental force between electromagnetic and gravitational forces with Planck length as its space time diameter. It is proposed that dark matter is that fundamental force carrying particle. By grand unification equation with space-time diameter, we found a coupling constant as per standard model “α<sub>s</sub>” for that fundamental force is 1.08 × 10<sup>-23</sup>. Its energy calculated as 113 MeV. A group of experimental scientists reported the energy of dark matter particle as 17 MeV. Thorough review may advance science further. 展开更多
关键词 General Relativity Quantum Mechanics Space Time Dark Matter A New fundamental Constant “K”
下载PDF
Frame Length Dependency for Fundamental Frequency Extraction in Noisy Speech
3
作者 Md. Saifur Rahman Any Chowdury +2 位作者 Nargis Parvin Arpita Saha Moinur Rahman 《Journal of Signal and Information Processing》 2024年第1期1-17,共17页
The fundamental frequency plays a significant part in understanding and perceiving the pitch of a sound. The pitch is a fundamental attribute employed in numerous speech-related works. For fundamental frequency extrac... The fundamental frequency plays a significant part in understanding and perceiving the pitch of a sound. The pitch is a fundamental attribute employed in numerous speech-related works. For fundamental frequency extraction, several algorithms have been developed which one to use relies on the signal’s characteristics and the surrounding noise. Thus, the algorithm’s noise resistance becomes more critical than ever for precise fundamental frequency estimation. Nonetheless, numerous state-of-the-art algorithms face struggles in achieving satisfying outcomes when confronted with speech recordings that are noisy with low signal-to-noise ratio (SNR) values. Also, most of the recent techniques utilize different frame lengths for pitch extraction. From this point of view, This research considers different frame lengths on male and female speech signals for fundamental frequency extraction. Also, analyze the frame length dependency on the speech signal analytically to understand which frame length is more suitable and effective for male and female speech signals specifically. For the validation of our idea, we have utilized the conventional autocorrelation function (ACF), and state-of-the-art method BaNa. This study puts out a potent idea that will work better for speech processing applications in noisy speech. From experimental results, the proposed idea represents which frame length is more appropriate for male and female speech signals in noisy environments. 展开更多
关键词 Pitch Estimation fundamental Frequency BaNa ACF Frame Length
下载PDF
Seismology in the Light of Fundamental Sciences
4
作者 Bychkov Serguei 《Open Journal of Earthquake Research》 2024年第1期84-112,共29页
According to the definition, seismology is a science that studies the processes and causes of seismic phenomena and the structure of the Earth, i.e. a scientific discipline that studies the movement of blocks of rocks... According to the definition, seismology is a science that studies the processes and causes of seismic phenomena and the structure of the Earth, i.e. a scientific discipline that studies the movement of blocks of rocks of the Earth’s crust and mantle and related phenomena. Seismology conducts research in the following areas and is designed to scientifically explain two main issues: 1) Study of the nature of seismic phenomena and the internal structure of the Earth. Why, how and where do seismic impacts occur? 2) Protecting humanity from the catastrophic consequences of seismic events. Is it possible to predict seismic impacts? Like any other scientific discipline, seismology is obliged to follow the laws of science and its fundamental principles. This article is devoted to the description of violations of the fundamental laws of science committed by seismologists in the study of seismic processes and raises the question of compliance of the stated research directions with the current level of development of sciences. Answering point No. 1, regarding the structure of the Earth, it is possible to recognize some successes of seismology, which nevertheless cause great doubts in the scientific community of geophysicists, because if the stratigraphic data of ultra-deep wells often refute [1] the conclusions made by seismologists on the structure of the Earth’s crust at shallow depth, then to assert something unambiguously about the structure of the mantle and at the present stage, seismology cannot. Answering the main questions of seismology, why seismic phenomena occur, and how earthquake energy is formed, seismologists have not had, and have not. Answering point No. 2, we can confidently say that in the matter of forecasting seismic phenomena, seismology has not advanced one iota over the past century, and as seismologists have been confused in the search for earthquake prediction algorithms, they are also confused without any hope of success. All that modern seismology can “boast” is the theory of Elastic recoil [2], the absurdity of which does not cause any doubt among the progressive part of geophysicists. But, the fact that most of the leading scientists-seismologists continue to piously believe the conclusions of the Elastic Recoil theory puts seismology in a humiliating position, because Mr. Reid’s theory is the clearest example of a false theory based on scientific incompetence of scientists, a model of brazen violation of the fundamental laws of science and the foundation of false and ignorant conclusions. Based on the results achieved, or rather on their absence, we regret to draw a sad conclusion: modern seismology is in the deepest decline, the cause of which is the incompetence of researchers as a result of their catastrophically low level of academic training, who stuff the scientific community with scientific geophysical rubbish, breeding similar ignoramuses in seismology. We understand that by asserting this, we offend most seismologists, but it is impossible to continue to tolerate this state of affairs in geophysics, because: “Amicus plato, sed magis amica est veritas.” Obviously, the time has come for a new meteorologist, Alfred Wagener [3], who will come and teach seismologists not to guess on coffee grounds, but to investigate seismic processes using the fundamental laws of science. In this article, we not only investigate the reasons for the unsatisfactory state of affairs in seismology, but also give our answers to the questions, of why earthquakes occur and how seismic energy is formed. 展开更多
关键词 SEISMOLOGY EARTHQUAKE fundamental Laws of Science
下载PDF
Fundamental Physical Constants and Primary Physical Parameters
5
作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2023年第1期190-209,共20页
Every four years the Committee on Data for Science and Technology (CODATA) supplies a self-consistent set of values of the basic constants and conversion factors of physics recommended for international use. In 2013, ... Every four years the Committee on Data for Science and Technology (CODATA) supplies a self-consistent set of values of the basic constants and conversion factors of physics recommended for international use. In 2013, the World-Universe Model (WUM) proposed a principally different depiction of the World as an alternative to the picture of the Big Bang Model. This article: 1) Gives the short history of Classical Physics before Special Relativity;2) Calculates Fundamental Physical Constants based on experimentally measured Rydberg constant, Electrodynamic constant, Electron Charge-to-Mass Ratio, and Planck constant;3) Discusses Electrodynamic constant and Speed of Light;4) Considers Dimensionless Fundamental Parameters (Dirac Large Number Q and Dimensionless Rydberg Constant α);5) Calculates Newtonian Constant of Gravitation based on the Inter-connectivity of Primary Physical Parameters;6) Makes a detailed analysis of the Self-consistency of Fundamental Physical Constants and Primary Physical Parameters through the prism of WUM. The performed analysis suggests: 1) Discontinuing using the notion “Vacuum” and its characteristics (Speed of Light in Vacuum, Characteristic Impedance of Vacuum, Vacuum Magnetic Permeability, Vacuum Electric Permittivity);2) Accepting the exact numerical values of Electrodynamic constant, Planck constant, Elementary charge, and Dimensionless Rydberg Constant α. WUM recommends the predicted value of Newtonian Constant of Gravitation in 2018 to be considered in CODATA Recommend Values of the Fundamental Physical Constants 2022. 展开更多
关键词 Classical Physics fundamental Physical Constants Electrodynamic Constant Speed of Light Dirac Large Number Dimensionless Rydberg Constant Newtonian Constant of Gravitation Self-Consistency of fundamental Physical Constants
下载PDF
Supreme Theory of Everything: The Fundamental Forces in Quantum Hysteresis
6
作者 Tardad Ulaanbaatar 《Journal of Applied Mathematics and Physics》 2023年第10期3274-3285,共12页
Gravity is considered one of the most mysterious of the four fundamental forces, a well-studied but poorly understood phenomenon in science. Newtonian physics and General Relativity have studied it from outside. Based... Gravity is considered one of the most mysterious of the four fundamental forces, a well-studied but poorly understood phenomenon in science. Newtonian physics and General Relativity have studied it from outside. Based on fundamental forces the Grand Unified Theory (GUT) and the Standard Model (SM) of Particle Physics study from the inside. GUT and SM explain three fundamental forces that govern the universe: electromagnetism, the strong force, and the weak force. The fourth fundamental force hopes that must be gravity, which the SM cannot adequately explain. The research aims to explain fundamental forces and their interactions based on the hysteresis law. The hysteresis law studies the fundamental forces from both inside and outside, so, I hope it can explain the rules and principles of the universe from the microworld to the macroscopic world. The united force of the three fundamental forces in high energy singularity (vertical asymptote) of the hysteresis becomes the weakest like weak interaction and continuously like strong force but has an infinite range like electromagnetic interaction. In this sense, it may be called gravity. Unfortunately, gravity is not an individual force;it is the positive singularity or high energy asymptotic sum of three fundamental forces emerging from the depth of the hysteresis of the subatomic particles. 展开更多
关键词 The fundamental Forces Alternative Fermi-Dirac Distribution The Vertical Asymptote of Hysteresis GRAVITY
下载PDF
The Significance of Generalized Gauge Transformation across Fundamental Interactions
7
作者 Bi Qiao 《Journal of Modern Physics》 CAS 2023年第5期604-622,共19页
The author of this paper has put forward a unified program of gauge field from the mathematical and physical picture of the principal associated bundles: thinking that our universe may have more fundamental interactio... The author of this paper has put forward a unified program of gauge field from the mathematical and physical picture of the principal associated bundles: thinking that our universe may have more fundamental interactions than the four fundamental interactions, and these basic interaction gauge fields are only the projection components to the base manifold, that is our universe, from a unified gauge potential or connection of the principal associated bundle manifold on the base manifold. These components can satisfy the transformation of gauge potential, and can even be transformed from one basic interaction gauge potential to another basic interaction gauge potential, and can be summarized into a unified equation, that is, the generalized gauge Equation (GGE), but the gauge potential or connection on the principal bundle is invariant, corresponding to the invariance of gauge transformation [1]. In this paper, we will continue to discuss this aspect concretely, and specifically construct a spatiotemporal model with the frame bundle as the principal bundle, and the tensor bundle as the associated bundle, so that the four fundamental interactions, especially the electromagnetic interaction and the gravitational interaction, can be reflected in the bottom manifold, that is, the regional distributions in our universe. Furthermore, this paper studies the existence of gauge transformation across basic interactions by establishing a model of gauge transformation of basic interaction field;it is found that the unified expression formula is GGE and the expression relation on the curvature of space-time. Therefore, the author discusses the feasibility of the generalized gauge transformation across the basic electromagnetic interaction and the basic gravitational interaction, and on this basis, specifically determines a method or way to find the generalized gauge transformation, so as to try to realize the last step of the “unification” of the four fundamental interactions in physics, that is, the “unification” of electromagnetism and gravity. 展开更多
关键词 Generalized Gauge Transformation Unification of fundamental Interactions Principal Bundle Connection and Curvature
下载PDF
Teaching Reform of Fundamentals of Combustion for Energy and Power Engineering Majors in Agricultural Colleges and Universities in the Context of New Engineering Course
8
作者 Shengyang GAO Yanhua MA 《Asian Agricultural Research》 2023年第11期46-49,共4页
The Fundamentals of Combustion course is an important compulsory course for Energy and Power Engineering Majors under the background of carbon peaking.According to the characteristics of teaching and scientific resear... The Fundamentals of Combustion course is an important compulsory course for Energy and Power Engineering Majors under the background of carbon peaking.According to the characteristics of teaching and scientific research at present,combined with the characteristics of complexity,interdisciplinary and rapid technology update of this course,this paper discusses the teaching content and teaching design of this course to meet the needs of talents of production,teaching and research under the background of new engineering course.It proposes more applicable teaching methods and practical means to broaden students horizons,stimulate students autonomous learning momentum,master the professional knowledge application ability,and cultivate innovative and competitive engineering professionals to adapt to the new energy strategy. 展开更多
关键词 New engineering course fundamentals of Combustion Undergraduate education Practice teaching Curriculum reform
下载PDF
Large Scale Fundamental Interactions in the Universe
9
作者 Qiao Bi 《Journal of Modern Physics》 2023年第S1期1703-1720,共18页
The author of this paper once attempted to propose a unified framework for gauge fields based on the mathematical and physical picture of the principal fiber bundle: that is, to believe that our universe may have more... The author of this paper once attempted to propose a unified framework for gauge fields based on the mathematical and physical picture of the principal fiber bundle: that is, to believe that our universe may have more fundamental interactions than the four, and these fundamental gauge fields are only components on the bottom manifold (i.e. our universe) projected by a unified gauge potential of the principal fiber bundle manifold;these components can satisfy the transformation of gauge potential, or even be transformed from one basic interaction gauge potential to another basic interaction gauge potential, and can be summarized into a unified equation, namely the generalized gauge equation expression, corresponding to gauge transformation invariance;so the invariance of gauge transformation is a necessary condition for unified field theory, and the four (or more) fundamental interaction fields of the universe are unified in a unified gauge field defined by the connection on the principal fiber bundle. In this paper, the author continues to propose a model of large-scale (gravitational) fundamental interactions in the universe based on the mathematical and physical picture of the principal fiber bundle, attempting to explain that dark matter and dark energy are merely reflections of these gravitational fundamental interactions that deviate in intensity from the gravitational fundamental interactions of the solar system at galaxy scales or some cosmic scales which are much larger than the solar system. All these “gravitational” fundamental interactions originate from the unified gauge field of the universe, namely the connection or curvature on the principal fiber bundle. These interactions are their projected representations on the bottom manifold (i.e. our universe) by different cross-sections (gauge transformations). These projection representations of the universe certainly are described by the generalized gauge equation or curvature similarity equation, and under the guidance of curvature gauge transformation factors, oscillate and evolve between the curvatures 1→0→-1→0→1 of the universe. 展开更多
关键词 Principal Bundle Gauge Similarity Transformation Dark Matter and Dark Energy Large-Scale fundamental Interaction Evolution of Universe
下载PDF
Unenumerated Rights Clauses and the System of Restriction on Fundamental Rights——Another Construction Plan for Article 51 of the Constitution of PRC
10
作者 杜强强 QIAN Chuijun 《The Journal of Human Rights》 2023年第1期91-108,共18页
According to constitutional jurisprudence in China,Article 51 of the Constitution is an unenumerated restrictive clause.Such theoretical construction fails to justify the differentiated restrictions established in the... According to constitutional jurisprudence in China,Article 51 of the Constitution is an unenumerated restrictive clause.Such theoretical construction fails to justify the differentiated restrictions established in the Constitution and makes it difficult to explain the constitutional status of human dignity. Article 51 implies the possibility of other theoretical constructions. It is not an unenumerated restriction clause but an unenumerated rights clause. It aims to provide guarantees for general freedom of action not enumerated in the Constitution rather than restricting fundamental rights. The actual benefit of this kind of theoretical construction lies in that it can establish the basis of the constitutional text for general freedom of action and promote the people’s correct understanding of the model of restriction on fundamental rights established by the Constitution of PRC. 展开更多
关键词 restriction on fundamental rights ¿legal construction ¿general freedom of action
下载PDF
高等教育出版社最新引进的Fundamentals of Chemistry
11
作者 卞江 《大学化学》 CAS 2004年第3期61-62,共2页
关键词 书评 高校 化学教材 《化学基础》 fundamentals of Chemistry》 教材内容 目标读者
下载PDF
Fundamental motor skills,screen-time,and physical activity in preschoolers 被引量:14
12
作者 E.Kipling Webster Corby K.Martin Amanda E.Staiano 《Journal of Sport and Health Science》 SCIE 2019年第2期114-121,共8页
Purpose: To examine the associations among preschoolers fundamental motor skills, screen-time, physical activity(PA), and sedentary behavior(SB).Methods: Children ages 3à4 years were enrolled in a prospective obs... Purpose: To examine the associations among preschoolers fundamental motor skills, screen-time, physical activity(PA), and sedentary behavior(SB).Methods: Children ages 3à4 years were enrolled in a prospective observational trial of PA. Trained assessors conducted the Test of Gross Motor Development-3 rd edition(TGMD-3), and the Movement Assessment Battery for Children-2 nd edition, and parent-reported child screen-time and sociodemographic information. Children wore an accelerometer for 7 days to examine SB and total PA(TPA). TPA was further characterized as moderateto-vigorous PA(MVPA) or vigorous PA(VPA). Mixed linear models were calculated, controlling for age(for TGMD-3), sex, household income, and accelerometer wear time(for accelerometry models), with childcare center as a random effect. The primary analysis reported on the cross-sectional baseline data of 126 children with complete fundamental motor skill and screen-time data; a subanalysis included 88 children with complete accelerometry data.Results: Children were 3.4 § 0.5 years of age(54% girls; 46% white, 42% African American, 12% other). A total of 48% lived in households at or below the federal poverty level. Children engaged in 5.1 § 3.6 h/day of screen-time. Children's screen-time was inversely related to the Movement Assessment Battery for Children-2 nd edition, manual dexterity skills percentile(b(SE) = ?1.7(0.8), p = 0.049). In the accelerometry subsample,children engaged in 5.9 § 0.9 h/day of TPA of which 1.7 § 0.6 h/day was MVPA. Boys engaged in more MVPA and VPA and less SB compared with girls(all p < 0.05). A higher TGMD-3, total score(b(SE) = 0.4(0.2), p = 0.017) and locomotor score(b(SE) = 0.7(0.3), p = 0.018) were associated with more VPA but not with TPA or MVPA. Screen-time and television in the bedroom were not related to SB, TPA, MVPA, or VPA.Conclusion: Children's motor skills were positively related to VPA but inversely related to screen-time. Further inquiry into the implications of high exposure to screen-time in young children is needed. 展开更多
关键词 fundamental motor SKILLS Physical activity PRESCHOOL Screen-time
下载PDF
HYBRID FEM WITH FUNDAMENTAL SOLUTIONS AS TRIAL FUNCTIONS FOR HEAT CONDUCTION SIMULATION 被引量:10
13
作者 Hui Wang Qing-Hua Qin 《Acta Mechanica Solida Sinica》 SCIE EI 2009年第5期487-498,共12页
A new type of hybrid finite element formulation with fundamental solutions as internal interpolation functions, named as HFS-FEM, is presented in this paper and used for solving two dimensional heat conduction problem... A new type of hybrid finite element formulation with fundamental solutions as internal interpolation functions, named as HFS-FEM, is presented in this paper and used for solving two dimensional heat conduction problems in single and multi-layer materials. In the proposed approach, a new variational functional is firstly constructed for the proposed HFS-FE model and the related existence of extremum is presented. Then, the assumed internal potential field constructed by the linear combination of fundamental solutions at points outside the elemental domain under consideration is used as the internal interpolation function, which analytically satisfies the governing equation within each element. As a result, the domain integrals in the variational functional formulation can be converted into the boundary integrals which can significantly simplify the calculation of the element stiffness matrix. The independent frame field is also introduced to guarantee the inter-element continuity and the stationary condition of the new variational functional is used to obtain the final stiffness equations. The proposed method inherits the advantages of the hybrid Trefftz finite element method (HT-FEM) over the conventional finite element method (FEM) and boundary element method (BEM), and avoids the difficulty in selecting appropriate terms of T-complete functions used in HT-FEM, as the fundamental solutions contain usually one term only, rather than a series containing infinitely many terms. Further, the fundamental solutions of a problem are, in general, easier to derive than the T-complete functions of that problem. Finally, several examples are presented to assess the performance of the proposed method, and the obtained numerical results show good numerical accuracy and remarkable insensitivity to mesh distortion. 展开更多
关键词 hybrid FEM fundamental solution variational functional heat conduction
下载PDF
TOPOLOGY OPTIMIZATION OF TRUSS STRUCTURE WITH FUNDAMENTAL FREQUENCY AND FREQUENCY DOMAIN DYNAMIC RESPONSE CONSTRAINTS 被引量:8
14
作者 Pan Jin Wang De-yu 《Acta Mechanica Solida Sinica》 SCIE EI 2006年第3期231-240,共10页
In this paper, adaptive genetic algorithm (AGA) is applied to topology optimization of truss structure with frequency domain excitations. The optimization constraints include fundamental frequency, displacement resp... In this paper, adaptive genetic algorithm (AGA) is applied to topology optimization of truss structure with frequency domain excitations. The optimization constraints include fundamental frequency, displacement responses under force excitations and acceleration responses under foundation acceleration excitations. The roulette wheel selection operator, adaptive crossover and mutation operators are used as genetic operators. Some heuristic strategies are put forward to direct the deletion of the extra bars and nodes on truss structures. Three examples demonstrate that the proposed method can yield the optimum structure form and the lightest weight of the given ground structure while satisfying dynamic response constraints. 展开更多
关键词 fundamental frequency dynamic response adaptive genetic algorithm topology optimization truss structure
下载PDF
SOME PROBLEMS WITH THE METHOD OF FUNDAMENTAL SOLUTION USING RADIAL BASIS FUNCTIONS 被引量:9
15
作者 Wang Hui Qin Qinghua 《Acta Mechanica Solida Sinica》 SCIE EI 2007年第1期21-29,共9页
The present work describes the application of the method of fundamental solutions (MFS) along with the analog equation method (AEM) and radial basis function (RBF) approximation for solving the 2D isotropic and ... The present work describes the application of the method of fundamental solutions (MFS) along with the analog equation method (AEM) and radial basis function (RBF) approximation for solving the 2D isotropic and anisotropic Helmholtz problems with different wave numbers. The AEM is used to convert the original governing equation into the classical Poisson's equation, and the MFS and RBF approximations are used to derive the homogeneous and particular solutions, respectively. Finally, the satisfaction of the solution consisting of the homogeneous and particular parts to the related governing equation and boundary conditions can produce a system of linear equations, which can be solved with the singular value decomposition (SVD) technique. In the computation, such crucial factors related to the MFS-RBF as the location of the virtual boundary, the differential and integrating strategies, and the variation of shape parameters in multi-quadric (MQ) are fully analyzed to provide useful reference. 展开更多
关键词 meshless method analog equation method method of fundamental solution radial basis function singular value decomposition Helmholtz equation
下载PDF
FURTHER IMPROVEMENT ON FUNDAMENTAL SOLUTIONS OF PLANE PROBLEMS FOR ORTHOTROPIC MATERIALS 被引量:4
16
作者 Sun Xiushan Cen Zhangzhi 《Acta Mechanica Solida Sinica》 SCIE EI 2002年第2期171-181,共11页
On the basis of the existing fundamental solutions ofdisplacements, further improvement is made, and then the generalfundamental solutions of both plane elastic and plane plasticproblems for ortho- tropic materials ar... On the basis of the existing fundamental solutions ofdisplacements, further improvement is made, and then the generalfundamental solutions of both plane elastic and plane plasticproblems for ortho- tropic materials are obtained. Two parametersbased on material constants a_1, a_2 are used to derive the rele-vant expressions in a real variable form. Additionally, an analyticalmethod of solving the singular integral for the internal stresses isintroduced, and the corresponding result are given. If a_1=a_2=1, allthe expres- sions obtained for orthotropy can be reduced to thecorresponding ones for isotropy. Because all these expres- sions andresults can be directly used for both isotropic problems andorthotropic problems, it is convenient to use them in engineeringwith the boundary element method (BEM). 展开更多
关键词 BEM fundamental solution plane elastoplastic problem orthotropic material
下载PDF
A FUNDAMENTAL SOLUTION FOR THE LAPLACE OPERATOR ON THE QUATERNIONIC HEISENBERG GROUP 被引量:4
17
作者 朱理 《Acta Mathematica Scientia》 SCIE CSCD 2002年第3期369-378,共10页
In this paper, the author studies the Laplace operator on the quaternionic Heisenberg group, construct a fundamental solution for it and use this solution to prove the L-p-boundedness and the weak (1-1) boundedness of... In this paper, the author studies the Laplace operator on the quaternionic Heisenberg group, construct a fundamental solution for it and use this solution to prove the L-p-boundedness and the weak (1-1) boundedness of certain singular convolution operators on the quaternionic Heisenberg group. 展开更多
关键词 Laplace operator fundamental solution singular integral kernels analysis on nilponent groups regularity of solutions
下载PDF
Single fundamental mode photonic crystal VCSEL with high power and low threshold current optimized by modal loss analysis 被引量:4
18
作者 解意洋 阚强 +2 位作者 徐晨 许坤 陈弘达 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第1期200-207,共8页
The characteristics of the photonic crystal vertical cavity surface emitting lasers(PhC-VCSELs) were investigated by using the full vector finite-difference time-domain(FDTD) method through the transverse mode los... The characteristics of the photonic crystal vertical cavity surface emitting lasers(PhC-VCSELs) were investigated by using the full vector finite-difference time-domain(FDTD) method through the transverse mode loss analysis. PhC-VCSELs with different photonic crystal structures were analyzed theoretically and experimentally. Through combining the dual mode confinement of oxide aperture and seven-point-defect photonic crystal structure, the PhC-VCSELs with low threshold current of 0.9 mA and maximum output power of 3.1 mW operating in single fundamental mode were demonstrated. Mode loss analysis method was proven as a reliable and useful way to analyze and optimize the PhC-VCSELs. 展开更多
关键词 vertical cavity surface emitting lasers single fundamental mode mode loss
下载PDF
Social-ecological correlates of fundamental movement skills in young children 被引量:2
19
作者 Nan Zeng Susan L.Johnson +1 位作者 Richard E.Boles Laura L.Bellows 《Journal of Sport and Health Science》 SCIE 2019年第2期122-129,共8页
Purpose: To identify the social-ecological correlates associated with fundamental movement skills at the child, family, and environment levels in young children.Methods: Preschool children from 4 Colorado Head Start/p... Purpose: To identify the social-ecological correlates associated with fundamental movement skills at the child, family, and environment levels in young children.Methods: Preschool children from 4 Colorado Head Start/preschool centers were recruited from 2010 to 2012. Two hundred twenty-eight children(128 girls; age = 56.08 § 4.09 months; body mass index(BMI) z-score = 0.53 § 1.12(mean § SD); 42.1% Hispanic/Latino) and 159 families were included in the final analysis. Children's perceived competence and fundamental movement skills were assessed via the Pictorial Scale of Perceived Competence and Social Acceptance and the Bruininks-Oseretsky Test of Motor Proficiency, 2 nd edition. Data on the number of children in the family, parent age, BMI, education, employment status, family income, perception of child coordination, and home physical activity environment were collected via a questionnaire. Linear regressions adjusted for child BMI, age, sex, and school site were performed at each level.Results: Child perceived cognitive competence was positively associated with locomotor skills(p = 0.04; adjusted R2= 0.035) and object-control skills(p = 0.003; adjusted R2= 0.083) at the child level. Parent education, BMI, and perception of child coordination were positively associated with locomotor skills and explained 8.8% of variance, but only parent education was significant(p = 0.04) at the family level. In addition, physical environment was positively associated with locomotor skills(p = 0.02) and explained 5.5% of variance at the environment level.Conclusion: Social-ecological correlates associated with young children's fundamental movement skills are multidimensional and differ according to skill category at the child, family, and environment levels. 展开更多
关键词 Activity environment fundamental MOVEMENT SKILLS PARENT education Perceived cognitive competence PRESCHOOL children
下载PDF
Conformal analysis of fundamental frequency of vibration of simple-supported elastic ellipse-plates with concentrated substance 被引量:2
20
作者 齐红元 朱衡君 《Journal of Central South University》 SCIE EI CAS 2005年第S2期269-273,共5页
Aimed at calculating the fundamental frequency of vibration of special-shaped, simple-supported elastic plates, Conformal Mapping theory is applied, and the mathematical method of trigonometric interpolation with inte... Aimed at calculating the fundamental frequency of vibration of special-shaped, simple-supported elastic plates, Conformal Mapping theory is applied, and the mathematical method of trigonometric interpolation with interpolation points mutual iterative between odd and even sequences in boundary region is provided, as well as the conformal mapping function which can be described by real number region between complicated region and unit dish region is carried out. Furthermore, in the in-plane state of constant stress, vibrating function is completed by unit dish region method for simple-supported elastic plates with concentrated substance of complicated vibrating region, and the coefficient of fundamental frequency of the plate is analyzed. Meanwhile, taking simple-supported elastic ellipse-plates as an example, the effects on fundamental frequency caused by eccentric ratio, the coefficient of constant in-plane stress, as well as the concentrated substance mass and positions are analyzed respectively. 展开更多
关键词 vibration fundamental frequency mode CONFORMAL mapping method of trigonometric interpolation ELASTIC
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部