Search

Modern timber buildings are more and more popular with their characteristics of green, environmental protection, low carbon. According to their structure, they are divided into light wood frame construction, sawn and log timber structures, glued laminated timber structures, log cabins. This paper analyzes the structure supporting structural system of log cabins, from material requirements, structural design to production process, supplemented by practical case to demonstration, to explore the design method of log cabin’s structure supporting system.

A shape optimization method based on strain energy is proposed for framed structures. This method combines free nodal shift, or restricted nodal shift on a specified line in the structural geometry. The optimization is based on nodal sensitivity information to amend the structural shape to achieve a structure with minimum strain energy. In this method, the design parameters, such as initial structure, supporting conditions, spatial constraints, etc, have significant influence on the final structural form; so various structural forms can be obtained by changing these design parameters in the project design phase. A numerical example is provided to illustrate the validity of this method and the mechanical behaviour of the structure. Results show that this can effectively reduce the structural bending moments and ensure sufficient structural stiffness.

Determining the freezing pipe spacing, the freezing reinforcement required range and method, acquiring the development and distribution patterns of frozen soil wall temperature field are the key issues needed to be addressed when using vertical freezing method for the soil reinforcement at shield shaft. Based on the shield launching project of the cross-river shield tunnel of Nanjing subway line 10 and the finite element numerical analysis software, the development and distribution patterns of different distance between freezing pipes of the vertical frozen wall are studied. The numerical simulation shows that, it is feasible to use the numerical model to simulate the temperature field of vertical frozen wall. Decreasing the distance between freezing pipes causes a greater impact on the temperature field. When freezing pipe spacing increases to 0.1m, frozen wall cross-lap time increases of about 1 day. With the freezing pipe spacing increasing, the cross-lap time increases linearly. The temperature of frozen wall decreases with the distance between freezing pipes decreasing, and the strength of frozen wall is more uniform. Results and conclusions form this research may play a useful role to aid designs of similar projects in future.

Punch forming is widely used in many fields such as car industry, aviation, and mechanical industry. Along with the new requirement such as velocity, efficiency, costing of punch forming, there is more and more failure appearance. For example, fracture, fold and spring back. In this paper, a detailed analysis of punch forming is done by FEM(finite element method), and the stresses of punch forming are obtained at every phase of punch. This work is very useful for mold design, punch forming parameters set and material properties test.

In this paper, we study the neural networks with time delays. By using of the Homeomorphism theory and employing an inequality, constructing a new Lyapunov-Krasovskill functional, we give a new sufficient condition, which is independent of the delays, guarantying the existence, uniqueness of the equilibrium point and it’s global exponential stable. Meanwhile, the incorrectness of calculation in the previous Refs is pointed out. We therefore improve the previous results.

Effect of cationic polymer on granulation and COD removal efficiency in lab scale UASB reactors was examined, treating low-strength wastewater (COD 300-500mg l-1) at room temperature. It was shown that cationic polymer was more effective for enhancing sludge granulation and COD removal efficiency as compared to the control experiment (without additives). After day 166 of operation, the amount of granules size above 0.5mm accounted for 32.1% of total sludge, higher than that of control experiment (19.3%). At 1.03 kg COD m-3 d-1 of OLR and 9.8 h of HRT, the effluent VFA had a maximum value of 168mg l-1 and 240mg l-1 in Reactor A and B respectively. The polymer-amended reactor took 36days to receive 1.44 kg COD m-3 d-1 of OLR at the 7.8 h of HRT, shorter than the control reactor (54days). The two reactors obtained above 80% in COD removal efficiency. It is shown that UASB reactor can also achieve higher COD removal treating low strength wastewater at room temperature.