盾构顶管刀盘矩形断面切削率探究

该文针对矩形盾构顶管用刀盘断面切削率进行研究,构建了刀盘面特征点轨迹数学模型,应用LISP语言对其轨迹参数化设计进行编程,获得了合适的刀盘外周行星齿轮半径比η值,并基于该程序探讨行星齿轮大小径比ξ、内齿圈半径和长方形高之比R/a与断面切削率等的相互关系。在正方形断面中,如果仅考虑高的断面切削率,宜选择莱洛三角形单刀盘(ξ=4/3面板式);如果同时考虑较高的断面切削率和较低的刀盘面积率,宜选择双圆弧形单刀盘(ξ=2面板式)。在矩形断面中,为获得较高的断面切削率,宜将矩形宽高比控制在0.7~1.4。

矩形波导缝隙天线阵分析

矩形波导缝隙阵天线在机载雷达上获得广泛使用。它具有体积小、重量轻、口径效率高、宽角副瓣低等特点。文中分析了矩形波导缝隙天线阵 ,给出了方向性函数及方向图 ,编制了分析软件 ,形成了方向图数据文件供通用软件调用。

12R22.5绿色子午线轮胎胎面弧度高对接地性能的影响

基于ABAQUS有限元分析软件,建立12R22.5全钢载重子午线轮胎有限元模型。以胎面弧度高为变量,分析了胎面弧度高对轮胎接地性能的影响。结果表明,随着胎面弧度高增大,轮胎接地印痕形状从近似矩形转变为近似椭圆形,轮胎的抓地性能逐步下降;接地压力偏度值呈增大趋势,轮胎耐磨性能变差;适度减小胎面弧度高可提高轮胎抓地和耐磨性能。研究结果可对轮胎接地性能的分析方法和轮胎生产模具的优化提供参考。

含羞草匀浆液流变学行为及其对Maxwell方程的拟合

目的研究含羞草叶匀浆接受矩形波切变率后的力学反应性及其对Maxwell黏弹性体方程的拟合与修正,揭示含羞草叶匀浆在微弱剪切应力作用下,变为黏弹性体的过程,支持含羞草细胞内有物质在剪切应力下由液体向黏弹性体结构的转变。方法制备无细胞含羞草叶匀浆,采用美国Brookfield公司程序型DVⅡ流变仪,给匀浆施加0.1、1、2、4、8、10、12 s^(-1)等8种切变率的矩形波的作用前、作用中、作用后,在Windows下用该仪器公司提供的软件,编制自动采样程序,做实时数据采集、贮存、回归拟合与数据处理。并与形状相似的植物叶下珠的叶匀浆作了对照。结果(1)含羞草叶匀浆在施加矩形波切变率作用下,其应力-时间上升曲线可用Maxwell黏弹性体方程拟合;下降线形状虽与该方程相似,但在数值上有明显差异,加上“不可逆应力损失项”后则可拟合。(2)从该文所设计的8种切变率矩形波作用下含羞草叶匀浆应力-时间曲线形状可认为均属于黏弹性体类型,尤其在切变率0.1、1、2、4 s^(-1)等4种低切变率的条件更为明显。该文对它们的Maxwell方程松弛时间、应力平衡值和改良后方程的“不可逆应力损失项”的参数进行了计算,并对含羞草、叶下珠叶片匀浆悬浮液进行了比较,前者具有黏弹性体的特有应力-时间曲线形状与明显的方程松弛时间参数值,而后者则无;前者有比后者大20倍的平衡应力数值。结论该文实验支持微弱的剪切应力好像“酶”一样,可驱动含羞草叶匀浆发生类似于Maxwell黏弹性体的力学反应,推测其过程中由于细胞内的某些物质(如蛋白质或细胞骨架)按照时空安排进行三维结构重组并发生运动;而外加的应力撤销后,则慢慢地回复原先状态。认为应用切变率矩形波技术与改良后的Maxwell方程,是研究生物物质的黏弹性的一个定量手段,还认为矩形波的切变率控制在0.1~4 s^(-1)范围内是较敏感的,过大的切变率则难以显示或损坏生物物质本身内部的力学特性。

Yield Modeling of Rectangular Defect Outline

In integrated circuits, the defects associated with photolithography are assumed to be in the shape of circular discs in order to perform the estimation of yield and fault analysis. However,real defects exhibit a great variety of shapes. In this paper,a novel yield model is presented and the critical area model of short circuit is correspondingly provided. In comparison with the circular model corrently available, the new model takes the similarity shape to an original defect, the two-dimensional distributional characteristic of defects, the feature of a layout routing and the character of yield estimation into account. As for the aspect of prediction of yield, the experimental results show that the new model may predict the yield caused by real defects more accurately than the circular model does. It is significant that the yield is accurately estimated and improved using the proposed model.

Solution of rectangular bar forging with bulging of sides by strain rate vector inner-product

Abstract：ools. The effective strain rate for for determining the total pressure developed during forging of a rectangular bar forging with bulging was expressed in terms of four-dimensional strain rate vector. The inner-product of the vector was termwise integrated and summed. The integral mean value theorem was applied to determining the ratio of the strain rate components and the values of direction cosine of the vector and then an analytical solution of stress effective factor was obtained. The compression experiments of pure lead bar were performed to test the accuracy of the solution. The optimized results of total pressure by golden section search were compared with those of the indicator readings of the testing machine. It indicates that the optimized total pressures are 2.60%-10.14% higher than those measured. The solution is available and still an upper-bound solution.

Experimental evaluation on well pattern adaptability of ultra-low permeability reservoir using sandstone flat model

As for ultra-low permeability reservoir,the adaptability of common nine-spot well pattern is studied through large-scale flat models made by micro-fractured natural sandstone outcrops.Combined with non-linear porous flow characteristics,the concept of dimensionless pressure sweep efficiency and deliverability index are put forward to evaluate the physical models' well pattern adaptability.Through experiments,the models' pressure distribution is measured and on which basis,the pressure gradient fields are drawn and the porous flow regions of these models are divided into dead oil region,non-linear porous flow region,and quasi-linear porous flow region with the help of twin-core non-linear porous flow curve.The results indicate that rectangular well pattern in fracture reservoirs has the best adaptability,while the worst is inverted nine-spot equilateral well pattern.With the increase of drawdown pressure,dead oil region decreases,pressure sweep efficiency and deliverability index increase; meantime,the deliverability index of rectangular well pattern has much more rational increase.Under the same drawdown pressure,the rectangular well pattern has the largest pressure sweep efficiency.

Power allocation and mode selection methods for cooperative communication in the rectangular tunnel

For the multipath fading on electromagnetic waves of wireless communication in the confined areas,the rectangular tunnel cooperative communication system was established based on the multimode channel model and the channel capacity formula derivation was obtained.On the optimal criterion of the channel capacity,the power allocation methods of both amplifying and forwarding(AF) and decoding and forwarding(DF) cooperative communication systems were proposed in the limitation of the total power to maximize the channel capacity.The mode selection methods of single input single output(SISO) and single input multiple output(SIMO) models in the rectangular tunnel,through which the higher channel capacity can be obtained,were put forward as well.The theoretical analysis and simulation comparison show that,channel capacity of the wireless communication system in the rectangular tunnel can be effectively enhanced through the cooperative technology;channel capacity of the rectangular tunnel under complicated conditions is maximized through the proposed power allocation methods,and the optimal cooperative mode of the channel capacity can be chosen according to the cooperative mode selection methods given in the paper.

High efficient parallel numerical surface wave model based on an irregular quasi-rectangular domain decomposition scheme

To achieve high parallel efficiency for the global MASNUM surface wave model, the algorithm of an irregular quasirectangular domain decomposition and related serializing of calculating points and data exchanging schemes are developed and conducted, based on the environment of Message Passing Interface(MPI). The new parallel version of the surface wave model is tested for parallel computing on the platform of the Sunway BlueLight supercomputer in the National Supercomputing Center in Jinan. The testing involves four horizontal resolutions, which are 1°×1°,(1/2)°×(1/2)°,(1/4)°×(1/4)°, and(1/8)°×(1/8)°. These tests are performed without data Input/Output(IO) and the maximum amount of processors used in these tests reaches to 131072. The testing results show that the computing speeds of the model with different resolutions are all increased with the increasing of numbers of processors. When the number of processors is four times that of the base processor number, the parallel efficiencies of all resolutions are greater than 80%. When the number of processors is eight times that of the base processor number, the parallel efficiency of tests with resolutions of 1°×1°,(1/2)°×(1/2)° and(1/4)°×(1/4)° is greater than 80%, and it is 62% for the test with a resolution of(1/8)°×(1/8)° using 131072 processors, which is the nearly all processors of Sunway BlueLight. When the processor's number is 24 times that of the base processor number, the parallel efficiencies for tests with resolutions of 1°×1°,(1/2)°×(1/2)°, and(1/4)°×(1/4)° are 72%, 62%, and 38%, respectively. The speedup and parallel efficiency indicate that the irregular quasi-rectangular domain decomposition and serialization schemes lead to high parallel efficiency and good scalability for a global numerical wave model.

Spatial Dependent Spontaneous Emission of an Atom in a Semi-Infinite Waveguide of Rectangular Cross Section

We study a quantum electrodynamics(QED) system made of a two-level atom and a semi-infinite rectangular waveguide, which behaves as a perfect mirror in one end. The spatial dependence of the atomic spontaneous emission has been included in the coupling strength relevant to the eigenmodes of the waveguide. The role of retardation is studied for the atomic transition frequency far away from the cutoff frequencies. The atom-mirror distance introduces different phases and retardation times into the dynamics of the atom interacting resonantly with the corresponding transverse modes. It is found that the upper state population decreases from its initial as long as the atom-mirror distance does not vanish, and is lowered and lowered when more and more transverse modes are resonant with the atom. The atomic spontaneous emission can be either suppressed or enhanced by adjusting the atomic location for short retardation time.There are partial revivals and collapses due to the photon reabsorbed and re-emitted by the atom for long retardation time.

Convective Transport in Rectangular Cavities Partially Heated at the Bottom and Cooled at One Side

Laminar natural convection heat transfer inside air-filled, rectangular enclosures partially heated from below and cooled at one side is studied numerically. A computational code based on the SIMPLE-C algorithm is used for the solution of the system of the mass, momentum, and energy transfer governing equations. Simulations are performed for a complete range of heater size, for Rayleigh numbers based on the height of the cavity ranging from 10~3to 10~6, and for height-to-width aspect ratios of the cavity spanning from 0.25 to 4. It is found that the heat transfer rate increases with increasing the heater size and the Rayleigh number, while it decreases with increasing the aspect ratio of the cavity. Dimensionless heat transfer correlations are also proposed.

Laminar Periodic Flow and Heat Transfer in a Rectangular Channel with Tri-angular Wavy Baffles

This paper presents a numerical analysis of laminar periodic flow and heat transfer in a rectangular constant temperature-surfaced channel with triangular wavy baffles (TWBs).The TWBs were mounted on the opposite walls of the rectangular channel with inline arrangements.The TWBs are placed on the upper and lower walls with attack angle 45?.The numerical is performed with three dif-ferent baffle height ratios (BR=b/H=0.05 0.3) at constant pitch ratio (PR) of 1.0 for the range 100 ≤ Re ≤ 1000.The computational results are shown in the topology of flow and heat transfer.It is found that the heat transfer in the channel with the TWB is more effective than that without baffle.The in-crease in the blockage ratio,BR leads to a considerable increase in the Nusselt number and friction factor.The results indicate that at low BR,a fluid flow is significantly disturbed resulting in inefficient heat transfer.As BR increases,both heat transfer rate in terms of Nusselt number and pressure drop in terms of friction factor increase.Over the range examined,the maximum Nu/Nu0 of 7.3 and f/f0 of 126 are both found with the use of the baffles with BR=0.30 at Re=1000.In addition,the flow structure and temperature field in the channel with TWBs are also reported.

Loop Algebras and Bi-integrable Couplings

A class of non-semisimple matrix loop algebras consisting of triangular block matrices is introduced and used to generate bi-integrable couplings of soliton equations from zero curvature equations.The variational identities under non-degenerate,symmetric and ad-invariant bilinear forms are used to furnish Hamiltonian structures of the resulting bi-integrable couplings.A special case of the suggested loop algebras yields nonlinear bi-integrable Hamiltonian couplings for the AKNS soliton hierarchy.

Research on the Efficiency Evaluation for the Board Based on GT-AHP Method

The board of directors is the core of corporate governance mechanism. In order to enhance the operation efficiency of the board, and to further reduce the agency cost, effective appraisal of the efficiency of the board becomes urgent. This paper firstly uses graph transformation and matrix algorithm to analyze the performance evaluation factors of the board and establishes the ordered hierarchy structure of the appraisal indexes. Then, it calculates the index weights with the AHP method. Next, it sets up the efficiency appraisal index system of the board. At last, the paper gives an empirical analysis with an example.