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1.
刘柳  刘曦阳  向天曼 《海外英语》2011,(8):335-336,338
Robert Frost is one of the famous poets of the 20th century American literature who won the Pulitzer Prize for four times. The reason for his popularity is partially because he employs traditional verse form and iambic pentameter pattern in poem writing, but the most important reason for the reputation of his poems lies in the thematic concern of something universal, such as death and life, love and hate, war and peace, the good and the evil, the wisdom of human life and etc. . A brief analysis will be given in the following text about the wisdoms of human life embodied in Robert Frost’s poems from three aspects: 1. Relaxation and responsibility of man. 2. The decisions in life.  相似文献   

2.
In this paper modelling of the translational motion of transportation rail-guided cart with rope suspended payload is considered. The linearly moving cart,driven by a travel mechanism,is modelled as a discrete six degrees of freedom (DOF) dynamic system. The hoisting mechanism for lowering and lifting the payload is considered and is included in the dynamic model as one DOF system. Differential equations of motion of the cart elements are derived using Lagrangian dynamics and are solved for a set of real-life constant parameters of the cart. A two-sided interaction was observed between the swinging payload and the travel mechanism. Results for kinematical and force parameters of the system are obtained. A verification of the proposed model was conducted.  相似文献   

3.
The purpose of using life extending control for Black Hawk UH-60 helicopter is to make a trade-off between the handling qualities and the service life of critical components. An increase in service life span results in enhanced safety and the reduction in maintenance costs. This paper presents a design methodology of life extending control for structural durability and high performance of mechanical system, which is based on an explicit dynamic inversion control scheme. A real-time nonlinear fatigue crack growth model is built to predict fatigue damage resulting from the impact of cyclic bending stress on rotor shaft, which serves as an indicator of service life. The 4-axis gain- scheduled flight controller, whose gains are adjusted as a function of damage and flight velocity, is designed to regu- late roll attitude, pitch attitude, vertical velocity and yaw rate. The nonlinear system simulation results show that the responses can meet the requirements on ADS-33 Level 1 handling qualities and that the 4-axis decoupling control is realized. As the damage increases, the tracking performance is slightly degraded, which results in smaller transients in bending moment response.  相似文献   

4.
In this paper, numerical method is used to study the strain rate effect on masonry materials. A typical unit of masonry is selected to serve as a representative volume element (RVE). Numerical model of RVE is established with detailed distinctive modeling of brick and mortar with their respective dynamic material properties obtained from laboratory tests. The behavior of brick and mortar are characterized by a dynamic damage model that accounts for rate-sensitive and pressuredependent properties of masonry materials. Dynamic loads of different loading rates are applied to RVE. The equivalent homogenized uniaxial compressive strength, threshold strain and elastic modulus in three directions of the masonry are derived from the simulated responses of the RVE. The strain rate effect on the masonry material with clay brick and mortar, such as the dynamic increase factor (DIF) of the ultimate strength and elastic modulus as a function of strain rate are derived from the numerical results.  相似文献   

5.
Nonlinear vibration can cause serious problems in long span cable-stayed bridges.When the internal resonance threshold is reached between the excitation frequency and natural frequency,large amplitudes occur in the cable.Based on the current situation of lacking corresponding constraint criteria,a model was presented for analyzing the dynamic reliability of coupling oscillation between the cable and tower in a cable-stayed bridge.First of all,in the case of cable sag,the d'Alembert principle is applied to studying the nonlinear dynamic behavior of the structure,and resonance failure interval of parametric oscillation is calculated accordingly.Then the dynamic reliability model is set up using the JC method.An application of this model has been developed for the preliminary design of one cable-stayed bridge located on Hai River in Tianjin,and time histories analysis as well as reliability indexes have been obtained.When frequency ratio between the cable and tower is approaching 1∶2,the reliability index is 0.98,indicating high failure probability.And this is consistent with theoretical derivation and experimental results in reference.This model,which is capable of computing the reliability index of resonance failure,provides theoretical basis for the establishment of corresponding rule.  相似文献   

6.
Screenplay, as the basis of a film, is the basis of the success of a film as wel . The excel ent Hol ywood Screenwriting in sports mainly comes from real life and traditional sports literary. By the main clue of a leading role as the basic framework of screenwriting, with the exchange between prosperity and adversity, interspersed with love, family, and social life, it shows struggling and tough attitude of life; promotes the value of physical existence and meaning of culture extension and reproduces the sports life. Apart from established playwriting framework, there is an individualized aesthetic presentation, which also is known as personalization and Stylization of screenwriting, leaving room for extension and imagination.  相似文献   

7.
In this paper, numerical method is used als. A typical unit of masonry is selected to serve merical model of RVE is established with detailed to study the strain rate effect on masonry materias a representative volume element (RVE). Nudistinctive modeling of brick and mortar with their respective dynamic material properties obtained from laboratory tests. The behavior of brick and mortar are characterized by a dynamic damage model that accounts for rate-sensitive and pressuredependent properties of masonry materials. Dynamic loads of different loading rates are applied to RVE. The equivalent homogenized uniaxial compressive strength, threshold strain and elastic modulus in three directions of the masonry are derived from the simulated responses of the RVE. The strain rate effect on the masonry material with clay brick and mortar, such as the dynamic increase factor (DIF) of the ultimate strength and elastic modulus as a function of strain rate are derived from the numerical results.  相似文献   

8.
高虹 《海外英语》2011,(11):275-276
James Joyce is one of the greatest pioneers of Modern novel history.The Dead is the most famous story in his early short story collection Dubliners,and is widely recognized as one of the finest short stories in the English language.This study tries to analyze the hero Gabriel’s mind change:from "living dead" to "reviving after death" from his epiphany,indicating that there is merely a delicate line between the two:death is the end of life as well as the beginning of a new life for death actually carries within itself a new life.  相似文献   

9.
何燕 《海外英语》2013,(22):270-272
Metaphor is pervasive in every aspects of human life.However,metaphor is not only rhetorical device,also the part of cognition as perceptual and conceptualizing means for perceiving the surrounding environment which is regarded as the"bridge"for cross-culture.Metaphor as the essence of bilingua cognition is further elaborated from cross-culture metaphor’s nature,fea tures and the significance of understanding.  相似文献   

10.
This paper focuses on climate comfort degree evaluated from relationships between spatial characteristics and behaviors of a winter city.It is demonstrated that the influences of climatic factors on human comfort are remarkably different for different spatial characteristics and functions of the sites.An evaluation method of climatic comfort is propsed,in which attaining comfort is an adaptation process,and the dynamic changes in the process are according to the user’s subjective tendency to the variations of the spatial characteristics and functions of the space.The evaluation criteria are based on both physical and psychological hierarchy needs of a person,which include the spatial form for microclimatic conditions as well as the spatial social-economic characteristics of a site.To improve the local environment of a winter city by planning measurements,the Harbin Central Pedestrian Street is taken as an example in the application of the evaluation method,and different planning optimizing strategies are proposed accordingly.The results show that the pattern of climate comfort is characterized by reflecting the socialeconomic value and individual behavior characteristics.  相似文献   

11.
Teacher specialization is a subject with very strong practicality as regards its essence. This paper analyzes the main problems of the existing teacher professionalism, poses and argues the 3 hypotheses of teacher professionalism. Around the reality of teacher professionalism, the author brings forward and establishes a new teacher evaluation system, which reflects the diversity of the main body for the evaluation, the diversity of evaluation content and the multiple of evaluation process and result. The new pattern is conducive to the right direction of the practicality of teacher professionalism, reflected as follows: Teachers' whole course of specialized practice is setting out from students' life world, clasping the exploration and consideration of human nature with kindhearted and pitiful heart, opening students' soul world through the convection of the emotion and by stimulating one's volition so as to make knowledge get natural formulation.  相似文献   

12.
刘争 《海外英语》2013,(1):284-285
The essay expounds the philosophy of Thoreau’s "simplify" in aspect of meaning and reason.Closely connected with the relationship between human and nature,it enables us to see the point of a brooding,simple and sensible life of Thoreau.The end clarifies on a question:according to Thoreau,what is to have a simplify life? That’s to care for little,listen to one’s heart and do what one likes.The conclusion comes with an advocation that people keep a simple life with little greed,and take it as an ulti mate cure for the bothering life of today.  相似文献   

13.
Numerical exercises are presented on the thermally induced motion of internally heated beams under various heat transfer and structural boundary conditions. The dynamic displacement and dynamic thermal moment of the beam are analyzed taking into consideration that the temperature gradient is independent as well as dependent on the beam displacement. The effect of length to thickness ratio of the beam on the thermally induced vibration is also investigated. The type of boundary conditions has its influence on the magnitude of dynamic displacement and dynamic thermal moment. A sustained thermally induced motion is observed with progress of time when the temperature gradient being evaluated is dependent on the forced convection generated due to beam motion. A finite element method (FEM) is used to solve the structural equation of motion as well as the heat transfer equation.  相似文献   

14.
The life of shipboard cables will decrease due to the complex aging processes. In terms of the safety perspective, remaining life prediction of the cable is essential to maintain a reliable operation. In this paper, firstly, based on Arrhenius equation, residual life of new styrene-butadiene cable is calculated; result indicates that the degradation rate which changes with time is proportional to thermal temperature. Then second order dynamic model is adopted into the residual life prediction, combined with the time-temperature superposition method (TTSP), and a new residual life model is proposed. According to the accelerated thermal aging experiment data and Arrhenius equation, TTSP method demonstrates to be an efficient way for life prediction, and life at normal temperature can be estimated by this model. In order to monitor the state of styrene-butadiene cable more accurately, an improved residual life model based on equivalent environment temperature of cable is proposed, and life of cable under real operation is analyzed. Result indicates that this model is credible and reliable, and it provides an important theoretical base for residual life of cables.  相似文献   

15.
The use of vacuum interrupters(VIs)as the current interruption component for switches,circuit breakers,reclosers and contactors operating at distribution voltages has escalated since their introduction in the mid-1950’s.This electrical product has developed a dominating position for switching and protecting distribution circuits.VIs are even being introduced into switching products operating at transmission voltages.Among the reasons for the VI’s popularity are its compactness,its range of application,its low cost,its superb electrical and mechanical life and its ease of application.Its major advantage is its well-established reliability.In this paper we show how this reliability has been achieved by design,by mechanical life testing and by electrical performance testing.We introduce the“sealed for life”concept for the VI’s integrity.We discuss this in terms of what is meant by a practical leak rate for VIs with a life of over 30 years.We show that a simple high voltage withstand test is an easy and effective method for monitoring the long-term vacuum integrity.Finally we evaluate the need for routine inspection of this electrical product when it is used in adverse ambient environments.  相似文献   

16.
17.
A dynamic finite element method combined with finite element mixed formula for contact problem is used to analyze the dynamic characteristics of gear system. Considering the stiffness excitation, error excitation and meshing shock excitation, the dynamic finite element model is established for the entire gear system which includes gears, shafts, bearings and gearbox housing. By the software of I-DEAS, the natural frequency, normal mode, dynamic time-domain response, frequency-domain response and one-third octave velocity grade structure borne noise of gear system are studied by the method of theoretical modal analysis and dynamic response analysis. The maximum values of vibration and structure borne noise are occurred at the mesh frequency of output grade gearing.  相似文献   

18.
In order to share multimedia transmissions in mesh networks and optimize the utilization of network resources, this paper presents a Two-stage Evolutionary Algorithm (TEA), i.e., unicast routing evolution and multicast path composition, for dynamic multicast routing. The TEA uses a novel link-duplicate-degree encoding, which can encode a multicast path in the link-duplicate-degree and decode the path as a link vector easily. A dynamic algorithm for adding nodes to or removing nodes from a multicast group and a repairing algorithm are also covered in this paper. As the TEA is based on global evaluation, the quality of the multicast path remains stabilized without degradation when multicast members change over time. Therefore, it is not necessary to rearrange the multicast path during the life cycle of the multicast sessions. Simulation results show that the TEA is efficient and convergent.  相似文献   

19.
我的人生观     
How strange is the lot of us mortals! Each of us is here for a brief sojourn; for what purpose he knows not, though he sometimes thinks he senses it. But without deeper reflection one knows from daily life that one exists for other people-first of all for those upon whose smiles and well-being our own happiness is wholly dependent, and then for the many, unknown to us, to whose destinies we are bound by the ties of sympathy. A hundred times every day I remind myself that my inner and outer life are based on the labors of other men, living and dead, and that I must exert myself in order to give in the same measure as I have received and am often oppressively aware that I am engrossing an undue amount of the labor of my fellow-men. I regard class distinctions as unjustified and, in the last resort, based on force.I also believe that a simple and unassuming life is good for everybody, physically and mentally.  相似文献   

20.
Information and communication are important elements in the growth of societies; they determine the characteristics of the societies. Multipurpose Community Access Points as the lowest locus of the information receiving and transmitting, data storage and retrieval, and also as the locus for the basic interaction among members of the community will presume to contribute a lot to community development especially to improve the quality of life as the whole. E - Learning is a process of transfer of Information (knowledge), in the sense of science, and values (social, cultural, ethical and moral values). E-government is an application of ICT to enhance government administration. Its contents may be very complex, but it is meant to enhance public services. Due to the social and cultural implications ICT is also said as civilizing. The use of ICTs has social, economic and cultural implications to reach civil society.  相似文献   

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