历史查询   



 为了更好的帮助您理解掌握查询词或其译词在地道英语中的实际用法，我们为您准备了出自英文原文的大量英语例句，供您参考。 
CarbonNanotubeBased NormallyonDriving UnderGate Field Emission Display Panel


A carbonnanotubebased normallyondriving undergate field emission display (FED) panel and its operation principle are presented.


The image is realized by modulating the voltage of undergate, whose value is less than the cathode voltage, to stop the cathode producing field emission electrons.


The results indicate that a uniform and large emission area can be obtained in this new undergate FED panel.


This study provides powerful theoretic support for the feasibility of this new kind of undergate FED panel.

 更多 


 Based on some information of field observation, the paper presents a preliminary investigation on steady nonuniform aerated flow in rectangular channel downstream of a highhead sluice gate. It points out that the usual practice is to design a narrow and short channel downstream of the gate and the flow is usually a decelerating one. Some flow characteristics such as the variation of mean air concentration along the flow, the gradient of air concentration along the depth and the side wall effect... Based on some information of field observation, the paper presents a preliminary investigation on steady nonuniform aerated flow in rectangular channel downstream of a highhead sluice gate. It points out that the usual practice is to design a narrow and short channel downstream of the gate and the flow is usually a decelerating one. Some flow characteristics such as the variation of mean air concentration along the flow, the gradient of air concentration along the depth and the side wall effect on air entrainment, are quite different from those encountered in wide and shallow channels. Hence the empirical formula for wide channels for computing the water surface profile cannot be used for narrow channels. The author, with due consideration pointed above, gives an analytical treatment of plotting surface profile for the latter case. With the introduction of a parameter"σ" characterizing the related flow phenomena a simple formula is recommended as logσ=1.77+0.0081(V~2/gR) where σ=the ratio of the difference between the water depths in an aerated flow and in the corresponding nonaerated flow of the absolute channel roughness, V=sectional mean velocity of nonaerated flow, g=gravitational acceleration, R=hydraulic radius of the crosssection of nonaerated flow. Charts and illustrative examples are also included for reference for designers.  本文对深孔闸后矩形槽恆定不均匀掺气水流进行了初步探讨。文中指出,在通常工程布置条件下,此种渠槽一般属于窄短渠槽,且水流沿程多呈減速流动,因而掺气水流运动的某些特性,如:水流的沿程平均掺气浓度变化规律、沿垂向的摻气浓度梯度、以及边墙对掺气量的影响等,均与宽浅渠槽中的掺气水流不同.文中针对上述特点,根据一些原型观测成果,提出了适用于此类布置的摻气水面线计算公式,并在原型中初步得到较好的验証.文末列有图表算例以供设计计算参考。  This paper studies the flowing characters of the double sluice openings with a drop down flow in the gate shaft through the body of a certain gravity dam and analyses particularly their effect on the discharge capacity. The principles and methods of calculating the discharge capacity of double sluice openings with a drop down flow in the gate shaft have been proposed and the formulas for calculating the discharges are listed with their corresponding coefficients given.  本文研究了某重力坝坝身双层孔洩水和闸门井串水的水流特点，着重分析了它们对 洩流能力的影响。文中提出了双层孔洩水和闸门井串水时洩水孔洩流能力的计算原则及 方法，列出了流量的计算公式，并给出了一些经验系数值。  Among the difficult problems in hydraulics is the flow with a free urface,because, not known a priori,it has to be determined as a part of the solution.A finite element method based on the variational principle for variable domains is proposed for this type of problems. As shown in Fig.1, the domain of solution is divided by a prescribed F curve into two subdomains,the fixed ABEPQGMNOA and the variable EFQPE with the free stream line as its boundary. Triangular elements and linear distribution of ψ are adopted... Among the difficult problems in hydraulics is the flow with a free urface,because, not known a priori,it has to be determined as a part of the solution.A finite element method based on the variational principle for variable domains is proposed for this type of problems. As shown in Fig.1, the domain of solution is divided by a prescribed F curve into two subdomains,the fixed ABEPQGMNOA and the variable EFQPE with the free stream line as its boundary. Triangular elements and linear distribution of ψ are adopted for the inner region,while trapezoidal elements and linear distribution of q2 for the variable domain. The unknowns to be solved for are the values of ψ of the nodes and the ordinates of points on the free surface. Equating the partial derivatives of the functional to zero furnishes enough equations,thus,the location of the free surface and the values of ψ are solved for simultaneously. The method is applied to free surface sluice gate flow over spillway and computed pressure distribution agrees satisfactorily with experimental results.  用有限元法计算水力学问题的困难之一是如何处理自由水面.因自由水面的位置在计算前是不知道的,求解的区域就不能预先确定.常用的方法是先假定自由水面的位置,把问题当作具有已知边界的问题来计算,然后校核沿自由水面的条件是否满足.如不满足,再重新修改自由水面的位置进行计算,直到能满足为止.本文建议,从可变区域的变分概念出发,把决定自由水面形状的座标和各结点的流函数值当作未知量,形成方程组同时求解.用这种方式可以减少计算的工作量,算出的溢流面压力分布资料和试验结果符合较好.   << 更多相关文摘 
相关查询  



