导标法在海港测量中的应用

一、前言 在港池及泊位测量中,我们常采用导标法进行定位。其基本原理是:在一规则的码头岸线两端布设一条平行于码头的基线。测量时在预计测线的测站点上安置一台经纬仪,垂直基线的方向上安置前后两导标,测船沿着导标方向按指定测线进行测量。通过观测测站点至测船的距离和与预计测线的偏角,从而计算出偏移距,在图板上按距离一偏移距,定出船位,然后连成航迹线。

Controlled illumination and seismic acquisition geometry for target-oriented imaging

The conventional method of seismic data acquisition geometry design is based on the assumption of horizontal subsurface reflectors, which often is not suitable for complex structure. We start from a controlled illumination analysis and put forward a method of seismic survey geometry design for target-oriented imaging. The method needs a velocity model obtained by a preliminary seismic interpretation. The one-way Fourier finite-difference wave propagator is used to extrapolate plane wave sources on the target layer to the surface. By analyzing the wave energy distribution at the surface extrapolated from the target layer, the shot or receiver locations needed for target layer imaging can be determined. Numerical tests using the SEG-EAGE salt model suggest that this method is useful for confirming the special seismic acquisition geometry layout for target-oriented imaging.

Error Analysis and Compensation of Strapdown Inertial Navigation System

Based on error analysis, the influence of error sources on strapdown inertial navigation systems is discussed. And the maximum permissible component tolerances are established. In order to achieve the desired accuracy (defined by circular error probability), the types of appropriate sensors are chosen. The inertial measurement unit (IMU) is composed of those sensors. It is necessary to calibrate the sensors to obtain their error model coefficients of IMU. After calibration tests, the accuracy is calculated by uniform design method and it is proved that the accuracy of IMU is satisfied for the desired goal.

Design and simulation for large parafoil fix line object homing algorithm

Traditional parafoil homing usually uses a point as object. As the mobility of parafoil is limited by its glide ratio and wind, in some cases when the parafoil scatter area is large, or the glide ratio of parafoil is small, the deviation of its landing point to object point will be arduous to control. Accordingly, during these situations, when parafoil is used in recovery of spacecraft or satellite, the landing area of parafoil can be set as a rectangle, and the object of parafoil can be set as a line segment. The thesis of this work is designing an algorithm for parafoil homing using line segment as object. The algorithm of wind velocity and direction calculation in different flying segments was also investigated. The algorithm designed navigates the parafoil to land into the predestined area and largely reduce the probability of recovery loads falling to unwanted area to damage houses and people.

Virtual local target method for avoiding local minimum in potential field based robot navigation

A novel robot navigation algorithm with global path generation capability is presented. Local minimum is a most intractable but is an encountered frequently problem in potential field based robot navigation.Through appointing appropriately some virtual local targets on the journey, it can be solved effectively. The key concept employed in this algorithm are the rules that govern when and how to appoint these virtual local targets. When the robot finds itself in danger of local minimum, a virtual local target is appointed to replace the global goal temporarily according to the rules. After the virtual target is reached, the robot continues on its journey by heading towards the global goal. The algorithm prevents the robot from running into local minima anymore. Simulation results showed that it is very effective in complex obstacle environments.

Gemcitabine plus carboplatin used as induction regimen for elderly patients with locally advanced unresectable non-small cell lung cancer

Objective:The purpose of this study was to evaluate the efficacy and safety of gemcitabine(GEM) and carboplatin(CBP) used as induction regimen in the treatment of elderly patients with locally advanced unresectable non-small cell lung cancer(NSCLC).Methods:Seventy-eight cases of elderly patients have been cytologically and pathologically confirmed with locally advanced unresectable NSCLC,the age of the patients ranged from 65 to 75 years.The patients were treated with the combined regimen of gemcitabine and cisplatin.GEM 1000 mg/m2 intravenously injected by drip on the 1st,8th day and the dosage of CBP was AUC 4 that was used on the 1st day,21 days apart to each cycle,most patients received 2 cycles.Treatment response was evaluated according to the criteria of RECIST(Response Evaluation Criteria in Solid Tumor),the side effect of the regimen was judged based on WHO criteria.Results:Seventy-eight patients were evaluated and received a total of 156 cycles chemotherapy.There were no complete regression that could be observed,but 32 cases had partial regression(PR),37 cases with no change(NC) and 9 cases with progression disease(PD).The overall response rate was 41.0%.The main side effects were hematological toxicity.Conclusion:The GC regimen could be used as induction treatment for elderly patients with locally advanced unresectable NSCLC,and the regimen could be well tolerated and is safe in terms of side effects.

Wideband electromagnetic characteristics modeling and analysis of missile targets in ballistic midcourse

The wideband electromagnetic characteristics of missile targets in midcourse are the foundation of midcourse attack-defense confrontation. This paper proposes a novel electromagnetic scattering modeling method for midcourse targets based on a pre- cise scattering center model, in which the nonideal scattering phenomenon, shielding effect and micro-motion are taken into consideration for the first time. Firstly, a precise scattering center model incorporating both the sliding scattering and artist- tropic scattering is established. Then the change rule of the target attitude is generalized, and a checking method of the scatter- ing center shielding effect is proposed for rotationally symmetric targets. Afterwards, a novel dynamic electromagnetic scat- tering model is presented, where the scattering center model updates along with the variation of the target attitude and can characterize the change of the electromagnetic characteristics of midcourse targets exactly. Finally, in light of the established model, the dynamic electromagnetic characteristics within different attitude angle bounds are analyzed by stages, and some useful conclusions are obtained. Experiment results from the measured data in anechoic chamber verify the validity of the proposed modeling method and relevant analysis.

Finite Element Method Formulation in Polar Coordinates for Transient Heat Conduction Problems

The aim of this paper is the formulation of the finite element method in polar coordinates to solve transient heat conduction problems. It is hard to find in the literature a formulation of the finite element method(FEM) in polar or cylindrical coordinates for the solution of heat transfer problems. This document shows how to apply the most often used boundary conditions. The global equation system is solved by the Crank-Nicolson method. The proposed algorithm is verified in three numerical tests. In the first example, the obtained transient temperature distribution is compared with the temperature obtained from the presented analytical solution. In the second numerical example, the variable boundary condition is assumed. In the last numerical example the component with the shape different than cylindrical is used. All examples show that the introduction of the polar coordinate system gives better results than in the Cartesian coordinate system. The finite element method formulation in polar coordinates is valuable since it provides a higher accuracy of the calculations without compacting the mesh in cylindrical or similar to tubular components. The proposed method can be applied for circular elements such as boiler drums, outlet headers, flux tubes. This algorithm can be useful during the solution of inverse problems, which do not allow for high density grid. This method can calculate the temperature distribution in the bodies of different properties in the circumferential and the radial direction. The presented algorithm can be developed for other coordinate systems. The examples demonstrate a good accuracy and stability of the proposed method.