南京南站主体钢结构混层法吊装施工

针对第三代大型铁路客运站房设计特点及施工难点,以南京南站屋面以下主体钢结构吊装为实例,经过吊装方案比选,提出了混层吊装法,用以解决施工现场复杂、场地狭小、构件规格大且数量多、工程量大且工期紧、专业交叉施工搭接繁多等技术难点。实践表明,混层吊装法不但切实可行,而且可以有效缩短施工工期,提高安装效率,满足大型客运站房复杂的施工要求,并形成了大型铁路客运站房主体钢结构混层法吊装施工技术。

Bi-level hybrid local search approach for three-dimensional loading problem with balancing constraints

This paper presents a bi-level hybrid local search(BHLS)algorithm for the three-dimensional loading problem with balancing constraints(3DLP-B),where several rectangular boxes with even densities but different sizes are loaded into a single cubic bin to meet the requirements of the space or capacity utilization and the balance of the center of gravity.The proposed algorithm hybridizes a novel framed-layout procedure in which the concept of the core block and its generation strategy are introduced.Once the block-loading sequence has been determined,we can load one block at a time by the designed construction heuristic.Then,the double-search is introduced;its external search procedure generates a list of compact packing patterns while its internal search procedure is used to search the core-block frames and their best distribution locations.The approach is extensively tested on weakly to strongly heterogeneous benchmark data.The results show that it has better performance in improving space utilization rate and balanced condition of the placement than existed techniques:the overall averages from 79.85%to 86.45%were obtained for the balanced cases and relatively high space-usage rate of 89.44%was achieved for the unbalanced ones.

Structure and properties of diffusive titanium nitride layers produced by hybrid method on AZ91D magnesium alloy

A diffusive titanium nitride layers were produced on AZ91 D magnesium alloy by a hybrid method which combines the titanium coating physical vapor deposition（PVD） with subsequent nitriding. The layers are composed of a thin surface zone of titanium nitrides and oxides, an intermediate titanium zone and Ti-Al-Mg type diffusive zone. Since the layers improve the corrosion resistance, the best corrosion resistance is obtained when the layers are produced on aluminum base sub-layer by oxynitriding.

Groundwater level prediction based on hybrid hierarchy genetic algorithm and RBF neural network

As the traditional non-linear systems generally based on gradient descent optimization method have some shortage in the field of groundwater level prediction, the paper, according to structure, algorithm and shortcoming of the conventional radial basis function neural network （RBF NN）, presented a new improved genetic algorithm （GA）： hybrid hierarchy genetic algorithm （HHGA）. In training RBF NN, the algorithm can automatically determine the structure and parameters of RBF based on the given sample data. Compared with the traditional groundwater level prediction model based on back propagation （BP） or RBF NN, the new prediction model based on HHGA and RBF NN can greatly increase the convergence speed and precision.

Application of Compactness Detection to Complicated Concrete-Filled Steel Tube by Ultrasonic Method

An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concrete-filled steel tubular column,the plane detection method and embedded sounding pipe method were adopted in the process of effectively detecting the column.According to the results of the plane detection method and embedded sounding pipe method,the cementing status of steel tube and concrete can be concluded,which cannot be judged by the hammering method in the rectangular steel tube-reinforced concrete.

Auto Identification of Rolling Layers in Roller-Compacted Concrete Dam

A scheme for identifying rolling layers in roller-compacted concrete (RCC) dam automatically was presented. First, a conceptual model was developed. Second, by using a computational geometry method, the auto identification of rolling layers and auto matching between rolling compaction machines and rolling layers were realized based on spatial control points. An application to the construction of Guandi RCC dam showed that the auto identification of rolling layers played an important role in ensuring the engineering quality.

Analysis on the Security Enhancement Model of Communication System based on Chaotic Encryption and Analytic Hierarchy Process

In this paper, we conduct research on the security enhancement model of communication system based on the chaotic encryption and analytic hierarchy process. The communication of the information network is completed by the communication protocol. The communication protocol can be divided into application layer, transport layer, network layer, link layer and physical layer. By using the communication protocol, the security control of the network communication can meet the needs of the information network security communication. This paper integrates the chaos system to further implement the robust system architecture. The algorithm of this paper tries to make the maximum value of the above three parameters in each iteration step by step and the output feedback to dynamically change these parameters. Compared with other algorithms, our method can adopt more related theories to perform the better result.

Investigation of Barree-Conway non-Darcy flow effects on coalbed methane production

Coalbed gas non-Darcy flow has been observed in high permeable fracture systems,and some mathematical and numerical models have been proposed to study the effects of non-Darcy flow using Forchheimer non-Darcy model.However,experimental results show that the assumption of a constant Forchheimer factor may cause some limitations in using Forchheimer model to describe non-Darcy flow in porous media.In order to investigate the effects of non-Darcy flow on coalbed methane production,this work presents a more general coalbed gas non-Darcy flow model according to Barree-Conway equation,which could describe the entire range of relationships between flow velocity and pressure gradient from low to high flow velocity.An expanded mixed finite element method is introduced to solve the coalbed gas non-Darcy flow model,in which the gas pressure and velocity can be approximated simultaneously.Error estimate results indicate that pressure and velocity could achieve first-order convergence rate.Non-Darcy simulation results indicate that the non-Darcy effect is significant in the zone near the wellbore,and with the distance from the wellbore increasing,the non-Darcy effect becomes weak gradually.From simulation results,we have also found that the non-Darcy effect is more significant at a lower bottom-hole pressure,and the gas production from non-Darcy flow is lower than the production from Darcy flow under the same permeable condition.

Determination of Natural Frequencies of Multilayered Plates by Mixed Finite Elements

Natural frequencies for multilayer plates are calculated by mixed finite element method. The main object of this paper is to use the mixed model for multilayer plates, analyzing each layer as an isolated plate, where the continuity of displacements is achieved by Lagrange multipliers （representing static variables）. This procedure allows us to work with any model for single plate （so as to ensure the proper behavior of each layer）, and the complexity of the multilayer system is avoided by ensuring the condition of displacements by the Lagrange multipliers （static variables）. The plate is discretized by finite element modeling based on a primary hybrid model, where the domain is divided by quadrilateral, both for the displacement field and static variables. This mixed element for plates was implemented and several examples of vibrations have been verified successfully by the results obtained by other methods in the literature.

An efficient hybrid model for fractured reservoirs

In this study, an efficient hybrid model is proposed to simulate the fluid flow in the reservoirs with multi-scale fractures, which cannot be easily modeled by neither the continuum models nor the discrete fracture models. In the proposed method, the small fractures are modeled by using an improved Multiple Sub-Region method, which can capture the strongly anisotropy of fracture elements and the effects of border region on the transmissibility and provide more accurate results, on the other hand, the large fractures are modeled explicitly as major fluid conduits by the Embedded Discrete Fracture Model. Then, an efficient numerical algorithm based on the Mimetic Finite Difference method is developed to solve the hybrid method. At the end, several numerical examples are carried out to verify the accuracy and applicability of the proposed numerical model.

Large Eddy Simulation of Methane Non-premixed Flame Using the Laminar Flamelet Model

The large eddy simulation (LES) using the steady laminar flamelet model is applied to a simple turbulent jet flame with 33.2% H2,22.1% CH4 and 44.7% N2 at the Reynolds number of 15,200 in order to validate the numerical methods and to investigate the flame structure.For the validation,the detailed experimental data of DLR-A flame is used.The numerical results are in reasonable agreement with experimental results except mass fractions of minor species.In the flow field,the break-down of the potential core,the vortex structure and the mixing intensity are well captured.In the combustion field,mass fractions of major species (H2O,CO2,CO) are well predicted quantitatively.Minor species are well predicted qualitatively.In the present study,the simulations conducted on the Cartesian and cylindrical grids with approximately 6.6× 10 5 nodes are compared.