Applied Mechanics and Materials Vols. 501-504

Abstract: Earth-to-Air Heat Exchangers (EAHE) represent a relatively simple technology that can be easily coupled with traditional HVAC systems as well as with hybrid systems in order to exploit the thermal capacity of the ground. The air is pre-heated in the cold season and pre-cooled in the warm season through the EAHE, thus smoothing the peak loads and reducing the primary energy consumption. The present paper presents an experimental set-up of an EAHE implemented in a rural area in the Sicily region, focusing on the selection of the type of soils and the characteristics of the monitoring system installed to collect information on the actual energy performance of the EAHE.

Abstract: GPS technology has been widely used since it was put into use. At present, the plane locational accuracy of GPS can already achieve millimeter level. But in terms of height, in order to apply the GPS ellipsoidal height in engineering practice, the geoid seperation or height anomaly of the corresponding point must be achieved to transform GPS geodetic height to normal height. In this paper, by taking 12 points from the national GPS control network of Xuxiang Village of Haining City as sample data, a BP neural network using 3-4-2-1 model structure is adopted and a nonlinear coefficient 1.1 is added in the response function. The height anomalies of the 5 points of the test set are calculated and the residual errors are achieved by comparing with the measured values. The internal and external coincidence accuracies of the model are 0.824cm and 0.922cm separately. The result shows that the model can completely meet the precision requirement of the fourth-grade leveling survey and can be used to transform the heights of the study area.

Abstract: This paper proposed the optical weighting combined mode of Least Square Support Vector Machine (LS-SVM) and BP Neural network. According to the measured data, this paper compared and analyzed the accuracy of LS-SVM model, BP Neural network model; quadratic polynomial curve surface fitting based on Total least-square algorithm and optimal weighting combined model, the data shows that the optimal weighting combined model has higher precision then others.

Abstract: In order to analyze the effect of using different creating correction algorithms and geometry of reference stations on the correction accuracy of a user station, interpolation coefficients (correction quality factors) were calculated based on six algorithms, three experiment networks and two users in different positions. These algorithms include Partial Derivative Algorithm (PDA), Distance-based Linear Interpolation Method (DLIM), Linear Interpolation Method (LIM), Low-order Surface Model (LSM), Linear Combination Model (LCM) and Least - Squares Collocation (LSC). By comparative analysis on these factors a conclusion can be drawn as follow, LIM and LCM algorithms are better than others in creating correction; the geometry of reference stations involved in calculation needs to be carefully considered.

Abstract: In this study, three years of the zenith tropospheric delay (ZTD) data observed from 46 International GNSS system (IGS) sites distributed in Asian area used to assess the effectiveness and accuracy of ZTD calculated from EGNOS model, and the application of the EGNOS model are also analyzed in Asian area. Relative to IGS observed ZTD, the bias and root mean square (RMS) for ZTD calculated from EGNOS model presents an obvious variation in temporal and spatial. These results provide a reference for the study of the tropospheric delay correction model, the real-time GNSS navigation and positioning.

Abstract: In this study, the basic principle of high-density electrical method and the basic theory of ground penetration radar (GPR) are described. The fault surveying at Wudang is taken as an example to summarize the image features of apparent resistivity section of fault and those surveyed by GPR. The applications in fault surveying of the two methods are compared.

Abstract: On account of unbonded prestressed concrete construction technology is a high demand specialized, strict operation, high technical content job [, so the construction quality control study of unbonded prestressed concrete play a vital role to the quality of the structure construction, impact the quality of the whole project. In view of this, this paper analysis and inductive the main point of it from three stages: before, under and after the construction, expect to play a role of reference and guidance to the engineering practice.

Abstract: Based on the PBA construction method of Changchun Liberation Road station metro line No.2, in order to get the optimization of construction sequence of six pilot tunnels, we use numerical simulation method and finite element software MIDAS GTS to establish the construction model of the station pilot tunnel. After comparing four excavation methods of the surface subsidence, we come to a conclusion that first up then down and first side then middle is the optimal excavation scheme. At the same time, we make models to analysis the necessity of making advance support before pilot tunnel construction. Pipe shed and small duct grouting pre support is very significant to the control of the subsidence of ground surface and vault.

Abstract: Through aspects of 19.650m high formwork construction preparation, installation, removal, quality standards, safety technical measures introduced during construction of tall security formwork.

Abstract: GFRP bars pile as supporting structures for application in foundation engineering, the construction process of molding and banding quality directly affects the safety of the structure, ease of construction and appearance quality. Through practice on multiple projects, worked out a more mature construction process, better control of the quality of construction projects GFRP bars, standardized operating procedures.