Abstract:Taking a mid-span continuous bridge as the research subject, the restoring force model of rubber bearing and the dynamical model of nonlinear analysis were established. Also, 100 earthquake wave records were chosen from PEER to conduct a series of nonlinear time-history analyses, and the relative displacement responses of rubber bearings were obtained. Based on the principle of Performance-Based Seismic Design and the theory of seismic vulnerability analysis, a method for determining four different damage indexes of laminated rubber bearing was proposed. According to traditional reliability probability analysis method, a curve between the spectral acceleration and the relative displacement ductility ratios of bearings was fitted, and the fragility curves of different bearings were formed. The results have demonstrated that bearing, especially the bearing on abutment, is more vulnerable than other bridge members under earthquake. Therefore, the seismic performance of bearing will be greatly improved if the thickness of rubber bearings is heightened or the PTFE sliding rubber bearings are adopted for abutment bearing.

Abstract:Based on theoretical and experimental analysis, the mechanical characteristics of steel plate shear walls with trilateral constraint in moment-resisting frame were studied. Based on the strip model of thin plate, the proposed model of steel plate shear walls with trilateral constraint was presented. The calculation formula of the shear strength of steel plate with trilateral constraint was presented in a simplified model, and the relationship between the angle of the tension field and the constraint stiffness of angle iron was derived. The four steel plate shear walls of the specimens with various ratio of width-thickness were tested by jack. The result has indicated that the calculation formula is better for steel plate with more than 143 of ratio of width-thickness, and the precision of the calculation formula of shear strength can meet the requirement. The principal stress direction and distribution measured by experiments inosculate completely with the simplified model. And the little ratio of width- thickness of steel plate required adequate anchorage to forgo failure of boundary. The accuracy of the calculation formula of shear strength decreased with the failure between the steel plate and the boundary frame.

Abstract:This paper applied a DE strategy to solve the size optimization problems of truss structures with stress and displacement constraints. We presented the basic principle of the original DE algorithm in detail, and then introduced the mathematical model for truss optimization. Several classical problems were solved by using DE algorithm, and the results were compared with those using other optimization methods. Numerical examples have shown that the DE algorithm has good convergence and stability and can be applied to effectively size the optimization of truss structures.

Abstract:Considering the shear capacity of elastic foundation and the shear deformation effect of beam, the equilibrium equation for Timoshenko beam resting on two-parameter foundation was derived. The initial parameter solution and transfer matrix method were presented. Using the initial parameter solutions, the finite element formulation and equivalent nodal forces of distributing load were deduced. When the shear rigidity of foundation was zero, the two-parameter foundation could be degenerated into Winkler foundation. When the shear rigidity was infinite, Timoshenko beam could be degenerated into Euler beam. Using the present finite element method, we analyzed inverse T type Timoshenko beam on two-parameter foundation under the concentrated loads on ends and stepped Timoshenko beam on two-parameter foundation under concentrated load, concentrated moment and distributing load. Results have shown that the present results are identical with others, which validate initia l parameter solutions, transfer matrix and finite element method.

Abstract:An emergency evacuation simulation model was constructed on the basis of cellular automata theory, and the corresponding visual simulation program was developed by using Visual Basic6.0. In order to simplify the algorithm in the implementation of evacuation simulation, walls and obstacles were used to divide the complex building plane into convex polygon regions, and then, doorways were used to link those regions to form a whole evacuation space. The program can be used for the evacuation simulation of buildings to figure out the critical number of occupants evacuated when serous congestion happens, so as to verify whether building layout satisfies the requirement of safety design standards, and therefore to improve the building layout.

Abstract:Based on the natural ventilation theory, the ventilation performance optimization of a new automatic wind catcher was proposed. Numerical simulation and experiment were carried out to study the relationship between the shape of exhaust grill and the wind pressure coefficient on its surface. In addition, the key parameters which enhanced the exhaust performance were proposed. The result has shown that the form with the best exhaust performance is the conical increaser. Compared with the wind catcher with no increaser, the exhaust rate of the conical increaser has improved by 14.3%. Furthermore, the wind catcher can achieve an air change rate of 8 times per hour in the typical weather of the winter in Beijing, which has a remarkable energy-saving effect.

Abstract:Based on the analysis on diagnosis knowledge of cold start fault for diesel engine, the running state parameters of the process of cold start in the diesel engine were processed by using clear sets to construct a fuzzy set. Some abnormities about the process of cold start in the diesel engine were diagnosed by using fuzzy inference algorithm, and an abnormity diagnosis method about the process of cold start in the diesel engine was put forward based on fuzzy logic inference. Application results reveal that the probability about abnormity of the start difficult was 0.752. Therefore, oil temperature and inflow manifold temperature should be checked. Application effects show that the abnormity diagnosis method about the process of cold start in the diesel engine is of high accuracy and large practicality.

Abstract:Based on the structure and working principle of a hexagonal spring tube energy-absorbing device for car crash, this paper utilized the SolidWorks, Hypermesh and LS-DYNA to establish a finite element model for the device, and analyzed the performances of the device, under a frontal crash condition whose weight is 1.5 tons and speed is 50 km/h. Simulation results have shown that the energy-absorbing device have very good performances. For example, a smaller invasive amount for car stringer(252.9 mm), a higher crashing energy absorption ratio(52.09%) and a lower maximum X-direction acceleration for car(58.8 g).The above indices show that the device can protect the vehicle and the people in the vehicle.

Abstract:From the view of design behavior，the merits of digital design system were analyzed，and then the evolution of digital design system was demonstrated.The related concepts about design behavior chain were established, and the computing method of design behavior quantity was proposed. Two digital design systems built by different product information modeling principles and software architecture technology were carried out to take behavior comparison experiment to complete the same product design task. Through quantitative analysis of the experimental data, the feasibility of discriminating the advantages and disadvantages of digital design system based on design behavioral experiments and important effect of such software system caused by different model principles and techniques were verified.

Abstract:To address the computing instantaneous frequency of the product function (PF) in local mean decomposition (LMD), a new instantaneous frequency of a signal computing method was introduced. This method is piece-wise wave based. Firstly, a signal was separated to a number of full waves. Then, the instantaneous phase of each full wave was defined by a set of monotonic increasing arcsine functions. Therefore, the instantaneous frequency of a signal was obtained. Theoretically, the instantanoues frequency obtained in this method was positive, stable and could guarantee the characteristic information of signal integrity. This method was applied to compute the instantaneous frequency of simulated signals and actual gear fault vibration signals, and the results were compared with those obtained in other methods. It has been shown that this method is quite suitable for extracting the instantaneous frequency of a signal.

Abstract:Based on the analysis of both the operating characteristics of doubly-fed induction generator（DFIG）and conventional control strategy of maximum power point tracking（MPPT）, a control strategy based on the constraint factor of amplitude-limit to smooth the output of active power was proposed. The expression and calculation method of constraint factor α was provided.Based on matlab/simulink simulation, a power system with one 9 MW wind farm and two synchronous machines was built. Experiment results have shown that, compared with the conventional MPPT control method, the proposed control strategy can smooth the active power of DFIG and weaken the rotor speed fluctuation of synchronous machines, so thus the grid frequency can be improved.

Abstract:Rad23 gene which participates in ubiquitin/26S proteasome pathway in Arabidopsis， is known to play important roles in plant development and responses to hormone. In order to study its function and molecular mechanism, an expression vector pCold-Rad23 was constructed and transformed into E. coli BL21. Then the recombinant fusion protein was induced by IPTG.The results of SDS-PAGE have shown that Rad23 fusion protein existed in a soluble form with a relative molecular mass 94 ku, which is fit for the molecular mass supposed from gene coding frame. Finally, the Rad23 recombinant fusion protein was used as an antigen to prepare polyclonal antiserum in mice. The western blot results have shown that the polyclonal antiserum has high specificity and can react to the native protein expressed in different tissues of Arabidopsis.

Abstract:An improved, rapid method to measure free-base nicotine in mainstream cigarette smoke accurately by commercial headspace solid phase microextraction (HS-SPME) combined with GC/MS was established. The factors which play important roles in the determination of free-base nicotine, such as the solvent used for preparation of standards, SPME fiber, pre-equilibrium time before HS-SPME, extraction temperature and time, desorption time, were optimized carefully. Furthermore, an experimental water correction factor based on the water content of particulate phase was established to correct free-base nicotine in actual samples. The precision of the method was evaluated with smoke samples of reference cigarettes (Kentucky reference 3R4F) and the RSD obtained was 8.3%. The calculated limit of detection (LOD) and limit of quantification (LOQ) were 0.2 and 0.5 μg/cig, respectively.

Abstract:Previous research on rice productivity potential models, based on a single point in space and then extrapolated, is not ideal and is difficult to scale up. This study designed a rice productivity potential forecast system,which makes comprehensive use of spatial data and attribute data by integrating the model with geographic information systems according to the characteristics of rice productivity potential model and raster computing function. Following the idea of the software engineering and using COM technology, ArcGIS Engine components were embedded in Visual Studio.NET 2005 development environment. This system can achieve the goals of more systematic model parameters, more efficient calculation and more accurate analysis. This system can be used to predict potential and dynamic rice production. It is also important for the management of agricultural resources.

Abstract:Because there are a large number of unreliable communication links in wireless sensor network applications, it is difficult to achieve energy efficiency and QoS guarantee.So an energy balanced and QoS guaranteed geographic opportunistic routing protocol (EQGOR) was proposed to solve this problem. Based on opportunistic transmit mechanism, we established the models of forwarding efficiency, forwarding delay, energy efficiency and residual energy, and then proposed an adaptive forwarding set optimization algorithm based on multi-objective particle swarm optimization algorithm, which takes into account both energy and QoS requirement to meet QoS requirement and extend network lifetime. The simulation results have shown that this routing performs better than the opportunistic routing GOR and the traditional multi-path QoS routing QuESt in QoS and energy efficiency.

Abstract:It is challenging for real-time database systems (RTDBs) to support transaction timeliness while preserving data freshness under unpredictable workloads. So this paper proposed a scheme for data and transaction quality management to solve this problem. A definition of data quality considering data characteristic in both time and value domain was given. Based on the definition, a data quality adjustment method was presented which adjusts update periods and dynamic similarity degree lower bounds. This scheme uses the adjustment method, feedback control and admission control to support Qos targets. Experiments have shown that the proposed scheme outperforms the existing schemes.