Applied Mechanics and Materials Vols. 90-93

Abstract: Based on the two-dimensional Direct Linear Transformation (DLT) principle of close-range digital photogrammetry and mathematical principle of the linear neuron, the equivalent relationship between linear neural network and the two-dimensional DLT of close-range digital photogrammetry is discussed. A neural network with 2 linear neurons, 6 input parameters and 2 output parameters is established to simulate the two-dimensional DLT. The network can be trained using a set of grid points in the control coordinate system with known world coordinates and pixel coordinates. The weights and biases of trained network contain camera interior and exterior parameters. A new digital photographic technique is put forward combined camera self-calibration based on neural network with non-linear pixel coordinates correction of lens distortion. The indoor survey test indicates that measurement is more accuracy. Meanwhile, the new technology is successfully used in crack monitor of a bridge pier.

Abstract: Based on the choice characteristic of least absolute estimation ,and the principle of the minimum of summation of residual absolute value,the GM(1,1) model is proposed to distortion inspecting and forecasting.Exemples show the precision of least absolute estimation is uncertain to be higher a little than that of least squares estimation when observation value contains gross error,and the precision of least absolute estimation is lower a little than that of least squares estimation when observation value doesn’t contain gross error.So least absolute estimation isn’t beter to GM(1,1).

Abstract: There are some losed datum or mistake datum when GM（1，1）model deals engineering matter,so equidistance GM(1,1) model is restricted and choosing non-equidistance GM(1,1) model is very necessary.The backgroung value functions of modeling research on non-equidistance GM(1,1) model is studied and is considered to be wrong,and strict backgroung value functions is advanced in the paper.The theory and practice approach of the strict method is introduced particularly.Feasibility and validity of this mothod is gained through surveying and mapping engineering .So, the paper has some significance of theory and practice.

Abstract: Based on the example of the No.4 Nanjing Yangtze River Bridge, the construction technics of precasting segmental girders by short-line is introduced. And the way of plant deformation monitoring as well as the establishment of horizontal and vertical construction control network in the precast plant are expatiated on. In addition, the measurement techniques during the installation of the fixed-mold, unfixed-mold, lineshape control techniques of the segmental girders, as well as the error correction theories during precasting process are discussed in particular. The short-line is successfully applied to the No.4 Nanjing Yangtze River Bridge, which shows its practical value in precasting segmental concrete bridges.

Abstract: Trigonometric leveling method is often used to connect the height over sea. Error analysis of trigonometric leveling is made. In order to automatically achieve the trigonometric leveling over long distance, an automatic trigonometric leveling system is put forward with the combination of GPS and the automatic target recognition (ATR) techniques in this paper. The primary design of the system prototype including the structure and the software is given. The practical principle tests are also made to prove the system performance. The results indicate that the leveling precision of the system can satisfy the requirement of fourth order leveling.

Abstract: The 2.5′×2.5′resolution local quasi-geoid is calculated using the global gravity field model and GPS/leveling data of region which points spacing is about 10km with the Bayesian- regulation BP neural network in this paper. The inner and outer precision of quasi-geoid are both superior 0.05m.The result indicat that the Bayesian regulation BP neural network could improve the precision of fitting and restrain the over-fitting in fitting. The region quasi-geoid excelled than 0.05m can be computed using the global gravity field model and about 10km baseline GPS/leveling data in smoothness region.

Abstract: To make full use of geodetic height results measured by GNSS and improve the accuracy that GNSS geodetic height convert to normal height, method of polynomial surface fitting has been selected in this article to research into fitting of the elevation. In the first place, for least squares estimation do not have the ability of resisting gross error, robust estimation is introduced to data preprocessing, which has solve the problem of distortion model effectively and then combines with specific engineering to make comparison and to analyze accuracy of polynomial surface fitting data of different orders. MATLAB has been used in programming design in the whole process, which has realized automatic processing of data.

Abstract: This type analyzes that the water square can be used in the implementation of rain and sewage diversion in the old city. Water square not only reduce infrastructure cost and nuisance to the public, but also achieve the effect of storm sewer system's optimized transformation, This type also study the feasibility of its implementation and design principle, at last it gives a conclusion about the water square.

Abstract: In this paper, new composite coagulants, polymeric ferric aluminum-polydimethyl diallylammonium chloride, were synthesized by combing Polymeric ferric aluminum chloride (PFAC) with polydimethyl diallylammonium chloride (PDMDAAC) under different molecular weight ratio (Aluminum to PDMDAAC, Wr=10, 4, 2 and 1). Furthermore, flocculating mechanisms and performance of these new composite coagulants were investigated in treating surface water. The growth of flocs during coagulation using composite coagulants were measured under optimal dosage and neutral conditions. The results indicated that the new composite coagulants exhibited better coagulation performance than PFAC for removing turbidity and dissolved organic matter. For the composite coagulants, the predominant coagulation mechanisms were bridge formation and charge neutralization.

Abstract: The kinetics of pumice for decomposition of p-chloronitrobenzene (pCNB) in aqueous solution were investigate. The experiment result indicated that ozonation alone and pumice-catalyzed ozonation of trace pCNB in aqueous solution followed the Pseudo-first-order kinetic model at the reaction temperature of 296 K and the initial pH of 6.86. The rate constant of pumice-catalyzed ozonation increase 149% compared with ozonation alone. In two processes mentioned above, the rate constants of degradation of pCNB were found to decrease with increasing of tert-butyl alcohol. The rate constant of ozonation alone appeared to be decreased 73%, respectively, decreasing 194% in the process of pumice-catalyzed ozonation. Under the conditions of this experiment, ozonation alone and pumice-catalyzed ozonation for degradation of pCNB were primarily oxidized by highly active hydroxyl radicals.