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1.
蔡萍 《海外英语》2012,(14):133-134,148
Metaphor is a common linguistic phenomenon and always realizes its value within a certain context.Metaphor uses words to indicate something different from their literal meaning-one thing is described in terms of another so as to suggest a likeness or analogy between them.A metaphor can easily be seen as a bridge which links and comprises the known and the unknown,the familiar and the unfamiliar.Some people hold that metaphor tends to be seen as a way of coloring the ordinary plain language.Meanwhile some people think that metaphor is regarded as a way of experiencing the world.An analysis on English and Chinese metaphor translation will help to strengthen our understanding of different languages as well as different cultures.This paper focuses on the structure and features of metaphor,correspondences and several techniques in metaphor translation.  相似文献   

2.
利用青岛大学—西门子共建小型自动化实验室良好的软硬件环境和学习条件,基于WinCC flexible及西门子S7-200PLC实现了对立体仓库系统的设计。利用WinCC flexible与PLC之间通过工业标准通信协议MPI多点通讯协议进行通信的方式,完成了对立体仓库模型系统的实时监控。实验证明,系统具有很高的实时性和可靠性。  相似文献   

3.
针对可编程控制器原有课堂讲授教学模式中存在的问题,采用WinCC flexible组态软件构建PLC仿真实践教学模型,并通过触摸屏模拟控制系统运行状态,丰富了教学内容,激发了学生的学习积极性,使教学过程更加生动形象.  相似文献   

4.
As hybrid vehicles introduced the motor, the vehicle structure has a significant change in the power matching. Adriver-vehicle-road closed-loop semi-physical simulation system, which makes real driving parts together with the simulation car,will bring convenience to the new car design. We used the computer software to simulate the road with a slope, curve and someother features based on the actual road condition, and analyzed the whole road scene in addition to geometry and physicalcharacteristics. Analyzing and constructing the vehicle dynamics basic template, appropriate changes to the template can obtainthe desired vehicle dynamics model with an external device to control the model vehicle. It combined the physical operation system with visual display, which gave us real driving feelings and increased the vehicle design predictive accuracy.  相似文献   

5.
A linear complex equation for slender ring shells overall-bending in a meridian plane is given based on E. L. Axelrad's theory of flexible shells. And the non-homogeneous solution is obtained from W. Z. Chien's solution for axial-symmetrical slender ring shells to investigate the overall-bending problem of Ω-shaped bellows subjected to pure bending moments. The values calculated in the present paper are very close to the existing experiment. Thus Chien's work on axial-symmetrical problems for ring shells has been extended to overall-bending problems.  相似文献   

6.
基于西门子S7—200PLC温度控制模块和S7—200CPU的PID功能,通过使用STEP7-Micro/WIN软件编程,对PID参数进行整定,实现对温度的自动控制.上位机采用WinCCflexible软件组态温度控制画面,增强了系统的可视化.  相似文献   

7.
Aiming to reduce fuel consumption and emissions of a dual-clutch hybrid electric vehicle during cold start, multi- objective optimization for fuel consumption and HC/CO emission from a TWC (three-way catalytic converter) outlet is presented in this paper. DP (dynamic programming) considering dual-state variables is proposed based on the Belhnan optimality principle. Both the battery SOC (state of charge) and the temperature of TWC monolith are considered in the algorithm simultaneously. In this way the global optimal control strategy and the Pareto optimal solution of multi-objective function are derived. Simulation results show that the proposed method is able to promote the TWC light-off significantly by decreasing the engine's load and improving exhaust temperature from the outlet of the engine, in comparison with original DP considering the single battery SOC. Compared to the results achieved by rule-based control strategy, fuel economy and emission of TWC outlet for cold start are optimized comprehensively. Each indicator of Pareto solution set shows the significant improvement.  相似文献   

8.
Through the research into the characteristics of 7-DoF high dimensional nonlinear dynamics of a vehicle on bumpy road, the periodic movement and chaotic behavior of the vehicle were found.The methods of nonlinear frequency response analysis, global bifurcation, frequency chart and Poincaré maps were used simultaneously to derive strange super chaotic attractor.According to Lyapunov exponents calculated by Gram-Schmidt method, the unstable region was compartmentalized and the super chaotic characteristic of the nonlinear system was verified.Numerical results by 4-order Runge-Kutta method presented the multiform dynamic behavior of the system.  相似文献   

9.
In this paper, a plug-in hybrid electrical vehicle (PHEV) is taken as the research object, and its dynamic performance and economic performance are taken as the research goals. Battery charge-sustaining (CS) period is divided into power mode and economy mode. Energy management strategy designing methods of power mode and economy mode are proposed. Maximum velocity, acceleration performance and fuel consumption are simulated during the CS period in the AVL CRUISE simulation environment. The simulation results indicate that the maximum velocity and acceleration time of the power mode are better than those in the economy mode. Fuel consumption of the economy mode is better than that in the power mode. Fuel consumption of PHEV during the CS period is further improved by using the methods proposed in this paper, and this is meaningful for research and development of PHEV.  相似文献   

10.
To solve the low power density issue of hybrid electric vehicular batteries, a combination of batteries and ultra- capacitors (UCs) could be a solution. The high power density feature of UCs can improve the performance of battery/UC hybrid energy storage systems (HESSs). This paper presents a parallel hybrid electric vehicle (HEV) equipped with an internal combus- tion engine and an HESS. An advanced energy management strategy (EMS), mainly based on fuzzy logic, is proposed to improve the fuel economy of the HEV and the endurance of the HESS. The EMS is capable of determining the ideal distribution of output power among the internal combustion engine, battery, and UC according to the propelling power or regenerative braking power of the vehicle. To validate the effectiveness of the EMS, numerical simulation and experimental validations are carried out. The results indicate that EMS can effectively control the power sources to work within their respective efficient areas. The battery load can be mitigated and prolonged battery life can be expected. The electrical energy consumption in the HESS is reduced by 3.91% compared with that in the battery only system. Fuel consumption of the HEV is reduced by 24.3% compared with that of the same class conventional vehicles under Economic Commission of Europe driving cycle.  相似文献   

11.
Collapses of transmission towers were often observed in previous large earthquakes such as the Chi-Chi earthquake in Taiwan and Wenchuan earthquake in Sichuan, China. These collapses were partially caused by the pulling forces from the transmission lines generated from out-of-phase responses of the adjacent towers owing to spatially varying earthquake ground motions. In this paper, a 3D finite element model of the transmission tower-line system is established considering the geometric nonlinearity of transmission lines. The nonlinear responses of the structural system at a canyon site are analyzed subjected to spatially varying ground motions. The spatial variations of ground motion associated with the wave passage, coherency loss, and local site effects are given. The spatially varying ground motions are simulated stochastically based on an empirical coherency loss function and a filtered Tajimi-Kanai power spectral density function. The site effect is considered by a transfer function derived from 1D wave propagation theory. Compared with structural responses calculated using the uniform ground motion and delayed excitations, numerical results indicate that seismic responses of transmission towers and power lines are amplified when considering spatially varying ground motions including site effects. Each factor of ground motion spatial variations has a significant effect on the seismic response of the structure, especially for the local site effect. Therefore, neglecting the earthquake ground motion spatial variations may lead to a substantial underestimation of the response of transmission tower-line system during strong earthquakes. Each effect of ground motion spatial variations should be incorporated in seismic analysis of the structural system.  相似文献   

12.
In this paper ,a hybrid approach was developed to investigate the transient responses of a multi-span non-uniform flexble spinning shaft with nonlinear and asymmetric supports.The non-uniform spinning shaft with variable parmeters was modeled as a Bernoulli-Euler beam column with sectional constant cross-section properties by the finite element method.The supporting stiffness behavior of the nonlinear supports was described as a piecewise-linear and asymmetric model.The equations of motion in the matrix form of a multi-span non-uniform spinning shaft with nonlinear and asymmetric supports were formulated using Hamilton‘s principle and the assumed mode method.As an example,a spinning rocket with many variable stiffness supports was numerically simulated by the direct integration method.The transient response and dynamic behavior of this rotate-dynamic system are analyzed.  相似文献   

13.
The shapes and geometrical parameters of nozzles are key factors for fluidics. The relationship among the reaction thrust, flow rate pressure, diameter do and length L of a cylinder nozzle is analyzed theoretically. The simulation of the flow field characteristics was conducted via the FLUENT computational fluid dynamics package. Effects of the inlet conditions and the nozzle dimensions on the reaction thrust of a water jet were addressed particularly. The reaction thrust experiments were performed on a custom-designed test apparatus. The experimental results reveal that a) the nozzle diameter and the inlet conditions exert great influence on the water jet reaction thrust; and b) for L≤4d0, where the nozzle is treated as a thin plate-orifice, the reaction thrust is independent of nozzle length; for L〉4d0, where the nozzle is treated as a long orifice, the reaction thrust can reach maximum under the condition of a certain flow rate. These findings lay a theoretical foundation for the design of nozzles and have significant value, especially for the future development of high-oressure water-let orooulsion technology.  相似文献   

14.
Reaction thrust of water jet for conical nozzles   总被引:1,自引:0,他引:1  
Clear knowledge on the reaction thrust of water jet is valuable for better design of water jet propulsion system. In
this paper, theoretical, numerical and experimental studies were carried out to investigate the effects of the nozzle geometry
as well as the inlet conditions on the reaction thrust of water jet. Comparison analyses reveal that the reaction thrust has a
direct proportional relationship with the product of the inlet pressure, the square of flow rate and two-thirds power exponent
of the input power. The results also indicate that the diameter of the cylinder column for the conical nozzle has great influence
on the reaction thrust characteristics. In addition, the best values of the half cone angle and the cylinder column length exist
to make the reaction thrust reach its maximum under the same inlet conditions.  相似文献   

15.
基于VR的火箭炮装填训练模拟器的设计   总被引:3,自引:0,他引:3  
针对某型火箭炮实装训练噪声大、磨损大、消耗高等缺点,提出了基于VR的火箭炮装填训练模拟器的设计,文中简述了模拟器的设计原则、总体结构,重点展示了模拟器的硬件构成、软件设计及模拟训练功能的实现,经教学试用,该模拟器达到了设计的要求。  相似文献   

16.
The rise of information technology coupled with the globalization of the economy has thrust the identity and sovereignty of the nation-state into sharp focus over the last two decades. Against this fast-changing background, the response of many countries has been to develop policies aimed at creating national information infrastructures (NII) - often with educational networking initiatives as an integral or pioneering element. Given the emerging global policyscape (Ball 1999) towards creating educational information networks this paper presents a comparative analysis of policy-making across Europe, East Asia and the USA. In analysing education networking in seven case-study countries, the paper emphasizes a political economy perspective; thus focusing attention on the role of the state and the varying relationship between education, economy and society. Having explored the varying motivations and objectives behind countries' education networking programmes the paper concludes by outlining an educational research agenda for future examination of NII policies as they continue to be implemented in developed nations over the next decade.  相似文献   

17.
The most common answer to the above question is — hot jet of gas comes out of the nozzle of the rocket engine at high speeds and as a reaction the rocket moves (is propelled) in the opposite direction [1]. But is this answer right? Let us explore what goes on inside a rocket engine and arrive at the right answer.  相似文献   

18.
The authors’ analysis of the chemical components and sedimentary characteristics of the well developed Triassic strata in the southeastern part of western Kunlun Shan led them to conclude that the sediments comprise a set of typical deep-water to semi-deep-water flysch that formed in the passive continental margin of the Qiangtang Block. This suit of strata had undergone strong deformation giving rise to a SW-thrusting duplex, imbricate fans, high-angle thrust fault, recumbent fold, SW-inverted fold, etc.. The deformational intensity weakens gradually southeastward. This is a foreland fold and thrust belt caused by the collision between the Qiangtang Block and the island are on the southern margin of the the Tarim Plate at the end of late Triassic. The sedimentary and deformational characteristics of the Triassic strata were used to reconstruct the evolution of this foreland fold and thrust belt as proposed below. Before the end of Triassic, this region was a passive continental margin in the north of the Qiangtang Block. The end of Triassic to Jurassic was a stage of thrusting, folding, uplifting and development of the foreland basin. The evolution of the fold and thrust was completed in Cretaceous. Project supported by NSFC (49872073) and Key Project of NSFC.  相似文献   

19.
On the basis of the current sheet model, a new analytical solution for permanent magnet (PM) bearings is developed. Compared with analytical methods based on the coupling energy model and the magnetic dipole model, the proposed one is more physically intuitive and convenient for engineering designers. According to the analytical model, the thrust characteristics of a novel PM thrust bearing is studied and verified by finite element analysis (FEA). In the proposed thrust bearing configuration, the rotor is composed of stacked PM tings with alternative axial magnetization directions, and the stator with alternative radial magnetization directions while copper rings are used to separate adjacent PM rings. A prototype PM thrust bearing with the proposed configuration is designed and fabricated. The performances of the PM thrust beating are experimentally validated. It is shown that the calculation accuracy of the presented analytical solution is satisfying.  相似文献   

20.
INTRODUCTIONKunlunShanlocatedatthejunctureofEur asiaandGondwanaisaveryimportantsubjectingeologicalresearch (Fig. 1 ) .ManygeologistsconductedresearchesinWesternKunlunShan(Panetal.,1 990 ,1 992 ,1 995,1 996;YaoandHsu ,1 994 ;Lietal.,1 996;Dingetal.,1 996;Matteetal.,1 996) .Triassicstrata…  相似文献   

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