An approach for improving the precision on short-range electronic distance measurement trigonometry
Consider the trigonometric leveling method is simple, flexible and less limited by terrain conditions, it commonly used to inconveniently implemented area. Through the total station rapid development, the horizontal distance measuring between station and target for the traditional triangulation has been substituted by a slope from the Electronic Distance Measurement(EDM) measured. When combined with the appropriate methods of observation and error correction, short-range EDM trigonometric levelingshould be able to improve the accuracy levels of precision leveling. It can be enhanced the efficiency of leveling jobs. The main error of short-range EDM trigonometric leveling is from atmospheric refraction, earth curvature and measurement error of height of instrument and prismatic. The first two errors can be reduced by reciprocal observation and intermediate point. Moreover, intermediate point just only measure the prismatic height between start and end point of the measuring leveling line, The results accuracy and observation efficiency is increased. In this study, about 2km selected sections of Highway 84 at Tainan Yujing District is chosen be an experimental zone. Three kinds of closed leveling line, 200m, 400m and 600m is consisted in this measured planning. Then, non-reciprocal observation, reciprocal observation and intermediate point are introduced to implement the measurement. Experimental results show that the EDM triangle elevation for 600m range or less, the fourth-level observation precision can be achieved in non-reciprocal observation. However, the loop closure error will be caused no any grade leveling accuracy. For the reciprocal observation or intermediate method, third-level precision of measurement accuracy and loop closure error can be accomplished. The results show that the short-range EDM triangle elevation has a higher level of feasibility to instead of the traditional measure.
Precise Height Determination Using Leap-Frog Trigonometric Leveling
Precise leveling has been used for the determination of accurate heights for many years. The application of this technique is difficult, time consuming, and expensive, especially in rough terrain. These difficulties have forced researchers to examine alternative methods of height determination. As a result of modern high-tech instrument developments, research has again been focused on precision trigonometric leveling. In this study, a leap-frog trigonometric leveling (LFTL) is applied with different sight distances on a sample test network at the Selcuk University Campus in Konya, Turkey, in order to determine the optimum sight distances. The results were compared with precise geometric leveling in terms of precision, cost, and feasibility. Leap-frog trigonometric leveling for the sight distance S=150 m resulted in a standard deviation of ±1.87 mm∕km and with a production speed of 5.6 km∕day .
Numerical Simulation of Induction Heating Process of Continuous Casting Slab
Compared with traditional blazing furnace, the Continuous Casting-Direct Rolling is an advanced manufacturing steel technology, which can reduce energy waste, decrease pollution and enhance efficiency. The characteristics of steels during induction heating are complex, the change of material properties with temperature makes exact analysis methods very difficult to implement. Therefore, a powerful computer aided numerical tool (i.e., finite difference analysis) is selected to numerically model the induction heating process in this paper. The mathematic model coupling with electromagnetic field and thermal field was established, and it was solved by finite difference method (FDM), thus the slab temperature distribution and its variation with time were obtained, and the characteristics in whole induction heating process were studied. To validate the program feasible, the results were evaluated and compared with experiment results, which showed that the simulation results are reliable and effective. The skin effect in heating process from the two results was studied and demonstrated, the temperature change caused by different parameters such as the induced power intensity and the corner radian were also presented, which indicate that the slab temperature can be heated uniformly through adjusting these parameters, thus the continuous casting slab can meet the rolling requirement.