In this paper, an instantaneous method for measuring leakage flow rate in pipeline is enabled by employing standard flow. Measuring equipment can be parallel connected to the pipeline, which promise the convenience and non-destruction. Standard flow is used to determine the internal volume of the measured equipment. And a nonlinear discrete-time tracking-differentiator has been designed to track the differential pressure. An algorithm is formulated to describe, to the extent possible, the relationship between leakage and standard flow. To date, similar methods have not been reported by any other groups.
In order to protect the sensitive information in collaborative manufacturing grid environment, an access control solution was proposed to satisfy the inherent dynamic natures of the Manufacturing Grid, including dynamic Business Flow and system environment. In this solution, the Manufacturing Context-Aware Grid Access Control (MG_TC-RBAC) model extended the Role based Access Control (RBAC) model, activity is used to encapsulate user's role and relevant permission, and the user's permission is accurate by task and environment context. This model can be used as a reference basis for the Manufacturing Grid security problem.
Eight simply supported dry-mixed self-compacting concrete (DSCC) beams and two normal concrete beams were tested and flexural behaviors of the tested DSCC beams were studied besides failure characteristics. When water ratio and coarse aggregate ratio are appropriate, based on the experimental results DSCC beams also have the failure process, including elastic, cracking, yield and ultimate point in bending, and the average strain of normal section can meet the plane section assumption, then the bearing capacity was theoretically analyzed. The calculated results showed that the ultimate moment of DSCC beam, which can meet the security of engineering application, can be estimated by the suggested formula of present Code for Design of Concrete Structures (GB50010-2002), whereas the calculated cracking moment can not. The calculated cracking moment using elastic theory can be in good agreement with the experimental values.
The environment restoring of the coal mining collapse area directly relates the region economy, the social stabilization, the ecological environment, also relates the sustainable development of mining area. And this is a serious problem for the mining area in China. In order to improve the environment of mining area, this paper analyze the presence of collapse area in China. this paper analyze the damages of coal mining collapse and the problems existing in the management and regulation of the collapse region. In addition to researching the way of soil management of coal mining subsidence area with Geographic Information System technology, he also exemplified the feasibility and necessity in soil management of the coal mining collapse area with Geographic Information System technology.
this paper proposed a new procedure for simulation of random wind velocity field with only a few random variables. The procedure starts with decomposing the random wind velocity field into a product of a stochastic process and a random field, which represent the time property and spatial correlation property of the wind velocity fluctuation respectively. Then the stochastic process for wind velocity fluctuations is represented as a finite sum of deterministic time functions with corresponding uncorrelated random coefficients by an innovative orthogonal expansion technology. Similarly, the random field is expressed as a combination form with only a few random variables by the Karhunen-Loeve decomposition. The proposed technique provides a basis to employ the probability density evolution method which was developed in the past few years to study the stochastic responses of general linear/nonlinear structural systems. In fact, using this method, the instantaneous probability density function and its evolution of arbitrary physical quantities of interest of the linear/nonlinear stochastic systems can be captured successfully and the reliability evaluation of MDOF systems could be obtained. A numerical example, which deals with a MDOF tall building subjected to wind loads, is given for the purpose of illustrating the proposed approach.
