预压加固软土路基沉降补方系数研究

通过对软土路基在预压荷载作用下产生的附加压力的非线性计算与分析,提出在计算软土路基工程补方量时,应结合地基的路堤断面尺寸与填土荷载大小(即填土高度)等因素综合分析考虑,以得出预压加固软土地基的沉降补方系数。

预压处理段路基的沉降补方系数控讨

高速公路预压处理段路基的沉降补方量与沉降量大小有直接的关系,还与路堤的沉降盆形状有关,求解沉降补方量就是准确确定沉降补方系数;随着高等级公路建设的发展沉降补方系数也在变化,不能沿用一个定值;一般路越宽、软土越厚、沉降越大,沉降补方系数越大。杭州湾大桥试验段的研究结果表明,真空联合堆载预压比堆载预压的加固沉降量要大35%￣45%,而沉降补方系数只大1.4%￣2.4%,充分表现出加固方法对沉降补方系数的影响。统计分析结果表明均方差和变异系数都很小时,可以用同类情形的沉降补方系数的平均值来计算沉降补方量。

Designing of Quasi-universal Compensator for Testing Aspherical Surface

According to the theory of testing aspherical surface by normal aberration compensation method,the designing method of quasi-universal compensator is studied.On the basis of third-order aberration theory,after calculating and optimizing with an optical design program,the structure parameters of a compensator are obtained.This new compensator could be used in Twyman-Green interferometer,and in measurement of a certain range of paraboloid ellipsoid and hyperboloid.The compensation accuracy is more than 0.02 λ .

Dynamic Polarization-Basis Compensation for Free-Space Quantum Communications

In polarization-encoded free-space quantum communications, a transmitter on a satellite and a receiver in a ground station each have a respective polarization zero direction, by which they encode and decode every polariza-tion quantum bit required for a quantum com-munication protocol. In order to complete the protocol, the ground-based receiver needs to track and compensate for the polarization zero direction of the satellite-based transmitter. Ex- pressions satisfied by amplitudes of the s-polarization component and the p-polarization component are derived based on a two-mirror model, and a condition satisfied by the reflec- tion coefficients of the two mirrors is given. A polarization tracking principle is analyzed for satellite-to-ground quanaun communications, and quantum key encoding and decoding prin- ciples based on polarization tracking are given. A half-wave-plate-based dynamic polariza- tion-basis compensation scheme is proposed in this paper, and this scheme is proved to be suitable for satellite-to-ground and intersatellite quantum communications.

Method of closed loop springback compensation for incremental sheet forming process

The closed loop control model was built up for compensating the springback and enhancing the work piece precision.A coupled closed loop algorithm and a finite element method were developed to simulate and correct the springback of incremental sheet forming.A three-dimensional finite element model was established for simulation of springback in incremental sheet forming process.The closed loop algorithm of trajectory profile for the incremental sheet forming based on the wavelet transform combined with fast Fourier transform was constructed.The profile of processing tool path of shallow dishing with spherical surface was designed on the basis of the profile correction algorithm.The result shows that the algorithm can predict an ideal profile of processing track,and the springback error of incremental sheet forming is eliminated effectively.It has good convergence efficiency,and can improve the workpiece dimensional accuracy greatly.

System for Measuring Elevator Guide Rail Quality and Its Calibration

A system for measuring the quality parameters of elevator guide rails is developed. The quality parameters the system can measure include straightness, flatness, squareness, width and height of the rail. The system consists of six parts：main guideway, auxiliary guideway, reference rail, saddle, control casing and measured rail. The guide rail to be measured is mounted on a bed. The straightness errors of surfaces are checked by five linear displacement sensors mounted on the saddle. The deviation of readings from the sensor, which is in contact with top guiding surface, gives the straightness error of the surface and height of the rail. The other four sensors are used to measure side guiding surfaces respectively and give other parameters including flatness on the surfaces, squareness, width and height of the rail. A novel calibration method is also developed to calibrate the straightness motion error of the system in horizontal and vertical directions. The deflection deformation of the measured rail is fitted by using a fourth-order polynomial. Experimental results show that the uncertainty of the system on the side surfaces after compensating the straightness motion error is less than 0. 01 mm, and the uncertainty of the system on the top surface after compensating the straightness motion error and the deflection deformation of the rail is less than 0. 03 mm.

A new compensation method for angular rate estimation of non-gyro inertial measurement unit

A new compensation method for angular rate estimation of non-gyro inertial measurement unit （NGIMU） is proposed in terms of the existence of aecelerometer mounting error, which seriously affects the precision of navigation parameter estimation. Using the accelerometer output error function, the algorithm compensates the posture parameters in the traditional algorithm of angular rate estimation to reduce the accelerometer mounting error. According to the traditional aceelerometer configurations, a novel nine-accelerometer confi-guration of NGIMU is presented with its mathematic model constructed. The semi-hardware simulations of the proposed algorithm are investigated based on the presented NGIMU configuration, and the results show the effectivity of the new algorithm.

The step-by-step CFD design method of pressure-compensating emitter

In order to improve the design and research and development (R & D) efficiency of the pressure- compensating drip irrigation emitter,a step-by-step computational fluid dynamics (CFD) design method was proposed based on CFD theory combined with the finite element method. By analyzing its hydraulic performance through the step-by-step CFD method,the prediction pressure-flow curve(p-Q curve) of the pressure-compensating emitter was obtained. Then the test samples were fabricated using rapid prototype and manufacturing(RP & M) technology. The emitters' hydraulic performance experiment was carried out and the experimental p-Q curve was obtained. The step-by-step CFD design method was verified by comparing the experimental p-Q curve with the prediction values,which showed that the prediction values met the experimental results well within the normal range of the emitter's working pressure. On this basis,the effect of the emitter structure on its pressure-compensating performance was studied,which showed that the height of the pressure-compensating region had significant effects on the emitter's pressure-compensating performance. Series products of the pressure-compensating emitter could be designed by changing the region's height.

The resettlement planning and practice of Three Gorges Project

Migrant resettlement is essential to the success of the Three Gorges Project (TGP),and the smooth implementation of resettlement is ensured by the resettlement planning and effective organization management.In the process of resettlement planning and implementation,systematic legislation and document support system is established;environmental capacity analysis and assets appraisal methods are introduced;resettlement sites are selected through in-depth analysis and comparison;the relationship between resettlement compensation and local development is correctly understood and considered,and reasonable resettlement schedules are well prepared.Through the establishment of efficient management system and capital management mode of "static control and dynamic management",as well as the timely adjustment of plan according to actual situations,the resettlement is accomplished smoothly.Thus,the social stability of the reservoir area is ensured;the economic development of reservoir area is promoted,and it has promoted successfully the improvement of legislation,regulations and techniques for land requisition and resettlement.The paper also discusses the theory and prospective work of resettlement.

An automatic compensation method on compression effect and surface elasticity measurement based on the deflection signal of AFM

Atomic force microscope （AFM）, as an important instrument in micro/nano operation, has been widely used to measure sampie＇s height information. However, the so called compression effect, due to force aroused from the contact of AFM tip with a sample surface, would result in imprecision of the surface＇s height measurement, i.e., the measured height is lower than expected. Up to now, there is not any effective and rapid method to attenuate this kind of measurement error. Thus, in this paper, an algorithm to obtain high accurate height measurement is proposed. Firstly, the concept of force curve is used to analyze the basic principle of the compression effect. Secondly, an automatic compensation method by fusing the height signal and the deflection signal is proposed. The proposed algorithm can also be used to obtain a surface elasticity image. Finally, in order to validate the proposed method, two experiments are conducted with respect to mufti-wall nano-carbon tubes on a silicon substrate and graphemes on a mica substrate.

A CONTROL ALGORITHM FOR RAPID MOVEMENTS NEAR THE RADIUS COMPENSATION SINGULARITY IN FIVE-AXIS END MILLING

When the five-axis CNC system executes the 3D cutter radius compensation function,the angle between two adjacent radius compensation vectors might become very large and the linear axes would move too fast if the tool orientation vector is close to the surface normal.The reason that results in this phenomenon is analyzed based on building the transmission relationship between the cutter contact point and the cutter location point.By taking the square-end tool as an example,an optimization algorithm to control the undesired movements is advanced.For the singular area where sudden change exists,the number of interpolation cycles is determined by the cutter feedrate,the limit speeds of machine axes and the maximum allowable angle between radius compensation vectors of adjacent NC blocks.The radius compensation vector of each interpolation cycle is obtained by a kind of vector rotation method.By maintaining the perpendicularity between the radius compensation vector and the tool orientation vector,the rapid movements of the linear axes are eliminated.A trial-cut experiment is performed to verify the correctness and the effectiveness of the proposed algorithm.