Search results

This Base on the the field data of water and sediment of Yangtze River estuary bifurcation in 2004 fiood season and 2005 dry season, the features and process of water and sediment transport Was analyzed by decomposition mechanism.The law of velocity of residual currentsediment transport rate per unit width and tidal punping effect,which in different season and tide,are focused on.The relationship between the features of water and sediment and channel wvolution was discussed through the results of the discharge of water and sediment,which is a basis in the future study of discharge of water and sediment in estuary.

This paper proposes an ultrasonic localization system, which adopts ultrasonic sensors to set up a network and realizes the information interactively with control center via 485 Bus. Using TDOA algorithm realizes the localization in indoor environment, and proposes a method to gain node information, on the basis, we can get a higher degree of response speed and accuracy of the system. Take an experiment by constructing an indoor localization test terrace, to prove feasibility of the theoretical.

A design method of reliability-based structural optimization has a powerful advantage because some random variables can be considered. However, the sensitivity analysis of reliability with respect to random variables is very complicated and its computational cost is very expensive. Thus, a response surface method is adopted for approximating the limit state function to improve computational efficiency. An iterative strategy is used to determine a response surface that is able to fit the limit state function in the neighborhood of the design point. A sequential response surface method is performed to satisfy the demand of accuracy in the process of reliability-based structural optimization. A numerical example is presented to demonstrate the computational efficiency of the proposed method.

In this paper, to investigative effects of preheating and postweld heat treatment on residual stress field in Q345 steel pipe welding, the finite element model was established. Preheating processes and postweld heat treatment process were simulated respectively. The results show that preheating can homogenize residual stress distribution of the weldment and decrease the residual stress. The heat treatment reduces the residual stress in inner and outer walls by 40% and 60% respectively and the stress distribution is more even and the stress concentration is reduced.

The effects of sewage sludge on combustion of loading alkali metal pulverized coal is carried out by thermogravimetric analysis (TGA). The result shows sewage sludge decreases initial release temperature and ignition temperature of volatile matter(VM) during the combustion of loading alkali metal pulverized coal. The combustion of fixed carbon in coal was promoted by the metal material in sludge when the sludge mixing ratio(SMA) was lower than 20% or inhibited because of the cover of sludge ash when SMA was higher than 40%. Comparison of stacking curves of sludge and measured curves of loading alkali metal coal, finds that: (1) there is no effect between sludge and coal, for the volatilization of water and small molecule substance, the combustion characteristic curves are superimposed in both experimental curves; (2) the co-combustion is interactional and interrestricted continuous change process, can't direct obtain from superimposition of curves, for the combustion of VM and fixed carbon. While SMA is lower than 20%, the samples have good combustion characteristic than pure coal.

The regional technological innovation capability is an important standard to weigh the development of regional economies, and it also plays a crucial role in the growth and competition of the regional economies. As there is really quite a difference in the capacities of regional technical innovation, this paper first makes a principal component analysis (PCA) on the indexes of capacities of regional technical innovation by adopting MARLAB. Then, it clusters them based on extracted principal component scores and the results were analyzed. Through the discussion on clustering results, it could help us to improve the knowledge of regional economic unbalance and capacity of regional technical innovation

A specimen for a static model test was designed to simulate a steel anchor box on the arch pylon of a cable-supported bridge. In order to reflect mechanical behavior of the prototype of the real structure, appropriate boundary conditions were determined by the comparison of FE analysis results from the real structure and the specimen. The design of the specimen successfully dealt with the difficulties in loading irregular structures. The FE analysis results show: the stress distribution on specimen was in good accordance with the real structure; the specimen can well represent the mechanical behavior of the anchor box on arch pylon.

Questions related to zonal disintegration such as difference between results from laboratory test and field monitoring test, as well as the effect of multi-axial stress level on zonal disintegration were discussed through numerical modeling by using a 3D numerical code called RFPA3D. Results show that the much smaller fracture spacing captured by laboratory test on zonal disintegration is due to the heterogeneity extent of the tested material. Zonal disintegration is an inherent character of heterogeneous rock mass, the more the heterogeneous the rock is, the larger the spacing between the adjacent fractures will be. The configuration of zonal disintegration is influenced by combination of stress level in three directions. Intact fracture rings can not be formed unless a nearly hydrostatic stress state exists in directions perpendicular to tunnel axis.

Metal rubber is a kind of pure metal structure of the porous material. The paper, starting from the internal structure of metal rubber, based on the theory of porous, based on dry friction nonlinear theory, establishing the unit model of porous metal rubber material, for the development of product design and application of the metal rubber material to provide a theoretical basis.

Water quality monitoring plays an important role in contamination control and environment protection. This paper describes an on-line multiparametric water quality monitoring system based on visible spectrophotometry, which combines embedded technology with GPRS telecommunication technology. This system can realize online wireless monitoring to concentrations of chromium (Cr), plumbum (Pb), A surfactant (AS), chemical oxygen demand (COD), ammonia nitrogen (AN), total phosphorus (TP) and total phenol (TPh) in real time. The mechanical structure, hardware circuit and software design of the system are completed. The absorption spectrums of pure water and MB-SDS complex have been measured. Preliminary experiments using a model machine show that each mechanism of the system runs well. Moreover, the monitor possesses many advantages, such as high degree of automation, high reliability, high efficiency, compact structure, small size, and so on.