Abstract:For the inverted catenary single-layer cylindrical reticulated shells with arch alignment in the form of catenary, the stability of three common grid configurations was analyzed and compared.A reasonable grid layout was determined, and the stability with single-layer cylindrical reticulated shells was compared. A large scale parameter analysis was carried out, including the effects of length-span ratio, raise-span ratio, member sectional dimension, initial geometric imperfection and unsymmetrical distribution of loads on the ultimate loads of the inverted catenary single-layer cylindrical reticulated shells. The results have shown that the slant rod of type I performs best overall stability capacity in the common grid configurations of inverted catenary single-layer cylindrical reticulated shells, and its stiffness and stability bearing capacity are greatly improved, compared with single-layer cylindrical reticulated shells. Raise-span ratio and length-span ratio influence the inverted catenary single-layer cylindrical reticulated shells significantly and have a good regularity, and the spacing of the structure transverse stiffening ribs should be less than the transverse width of the structure. Stability bearing capacity of the reticulated shells and section equivalent stiffness are in a linear relationship. The reticulated shells are proved to be sensitive to initial geometric imperfection when the initial imperfection value reaches 1/300 of the width, and the critical loads of the reticulated shells are maximally reduced by 57%. The reticulated shells are not sensitive to the asymmetric loads.

Abstract:Considering the common load bearing features of free section and anchoring section of the prestressed anchor bolt and using the double broken line model, which can present the damping properties of the soil-bolt surface strength, the analytical solutions between bolt resistance force and displacement was obtained based on the load transfer theory. Engineering example analysis verified the correctness of the theoretical derivation. The calculation results indicate that the stiffness and strength of the prestressed bolt are improved when the bearing capacity of free section is taken into account. The calculation results also show that the bearing capacity of the whole bolt increases, but the stiffness decreases on the contrary, while the free section length increases. So it is important to determine the rational length of free section in prestressed anchor bolts design and construction.

Abstract:To investigate the vertical prestress loss in concrete box girder webs with twice-tension, a rectangular thin plate test under twice-tension prestressed strand was conducted. At the same time, twice-tension vertical prestress loss used in a practical bridge was also tested, and was compared with the traditional vertical prestressed system using finishing rolling rebar. The test results have confirmed that the immediate vertical prestress loss can be reduced to less than 10% with the twice-tension technology, far less than that of finishing rolling rebar system. Twice-tension system can improve the efficiency of vertical prestress and shear reliability in box girder webs. At last, based on the test results, some factors that affect vertical prestress loss, including pipe roughness, compression of joint, deformation and retraction of anchorage, elastic compression of concrete, relaxation of tendons and creep and shrinkage of concrete, were discussed, and the corresponding methods of design taking value are proposed.

Abstract:For Buguzi River Bridge on Wulumuqi-Kash Railway, a three dimensional soil-pile-structure nonlinear interaction system model was built. Long-period and normal seismic waves were selected for three dimensional seismic response parallel computation of soil-pile-structure nonlinear interaction system, and the interface effect of pile-soil and speedup ratio of parallel computation were discussed. The results have shown that the interface effect of pile-soil leads to considerable vertical in-coordination. When considering the interface effect of pile-soil, the horizontal acceleration response of piles is decreased little and the vertical acceleration response of piles is increased greatly when compared with uniform excitation. Meanwhile, the horizontal and vertical displacement responses of piles are increased. The horizontal acceleration responses of lateral pile caps are smaller than that of medial pile caps, and that of vertical acceleration responses are opposite. Parallel computing was also performed to raise computational efficiency.

Abstract:Traffic loading data were collected from 20 toll stations，and 25 highways were videotaped to obtain relevant traffic information in various provinces in China. Directional distribution factor (DDF), lane distribution factor (LDF) and their influential causes were analyzed. The results have shown that DDF is typically within 50%~60%, while the number of equivalent single axle load (ESAL) in heavy traffic direction is within 50%~85% of the total ESAL. Therefore, pavements should be designed for two traffic directions separately if the traffic characteristics in the two directions exhibit significant difference. Traffic configuration has great impact on LDF. LDF of expressway is larger than that of other highways for two-lane traffic, while LDF of other highways is larger for three-lane traffic. Typical values of LDF are recommended for expressways and other highways, which can be used in pavement analysis and design.

Abstract:Through non-steady-state heat flow method and the PCK experimental device, the basic thermal physical quantities of fiber-reinforced composites were determined, the temperature on the heat transfer and wet migration characteristics was investigated, and the simplified equations between thermal conductivity, moisture diffusion coefficient and temperature were obtained. Considering the non-uniform of fiber-reinforced composites, one-dimensional humidity and heat transfer numerical analysis model of fiber-reinforced composites in fire condition were established. Numerical simulations of the material from crack initiation to thorough extension were conducted. Contrast material specimen at different times, the temperature distribution, pressure distribution and the crack depth, the peak intensity, the crack and burst characteristics were studied. Fiber-reinforced composites with different moisture contents after heating were tested to verify the performance of the thermal explosion and numerical analysis of indicators. The results have shown that the test and numerical analysis are basically the same and the pressure peak grows with the migration coefficient, making the materials durable.

Abstract:Based on the definition of intrinsic scale component (ISC), a new self-adaptive time-frequency analysis method,i.e., local characteristic-scale decomposition (LCD), was proposed. By using LCD, a complicated signal can be decomposed into a number of ISC,whose instantaneous frequencies have physical meaning.The processed simulation signal was analyzed by LCD and empirical mode decomposition (EMD). The analysis results have demonstrated the validity of the two decomposition methods. Moreover, LCD is superior to EMD in computational efficiency and restriction of end effects. In addition, LCD is also applied to fault diagnosis for roller bearing and the analysis results from the actual fault vibration signal have further proved the effectiveness of LCD.

Abstract:This paper investigated the safety behavior of a small car subjected to double-sided roof crush test, assessing the effect of different pitch and roll angle combinations on the roof crush strength and evaluating the difference in strength between near and far sides. A finite element model of Ford Fiesta was initially validated against the roof crush test, and was subsequently employed in virtual testing according to a full factorial method DOE (design of experiments) based on the variations of roll and pitch angles. The results have shown that the roll and pitch angles are a function of roof strength and greatly influence the overall collapse behavior. Within a 127 mm crush distance (5 inches), the strength of the two-sided roof decreases as the roll angle varies from 10° to 45° with a fixed pitch angle; the strength of the two-sided roof decreases as the roll angle increases from 5° to 15° with a fixed roll angle. Furthermore, the roof on the near side generally performs better and more strongly than the far side.

Abstract:A vehicle model of eight degrees of freedom was established. Then, based on dynamic simulation model, an approximate model between design variables, uncertain variables and objective function was built. Using double-nested IP-GA, the ride comfort of the model was improved. For IP-GA, the interval of objective function was obtained through the inner layer while the optimal variable was searched through the outer layer. Finally, the results were compared with those of certain optimization, which has shown the superiority of uncertain optimization.

Abstract:In order to decrease the additional moment caused by the height dimension of the six-dimensional F/T sensors, a novel thin six-dimensional F/T sensor with its height dimension below 15 mm was designed based on strain measurement with FEA, SDO, and ANN methods. Nonlinear decoupling and calibration of the sensor was performed to increase the performance of the sensor. The results of the calibration experiment show that the developed sensor possesses high performances and the design and optimization are rational, and its maximum nonlinearity error and the maximum coupling error are 0.15%F.S. and 1.6%F.S. respectively.

Abstract:Based on the three-layer fiber model and the coupling theory, the effective refractive index of the core mode and the cladding modes were numencally calculated in Long-period grating (LPG)，and the changing relation of the coupling coefficient of the cladding modes at the lowest few ones with varying wavelength were analyzed. It is revealed that the mode number of the maximum coupling coefficient of the cladding modes decreases with wavelength, the coupling coefficient with wavelength is different in different fiber parameters. These results are valuable for the design of long period grating, since the coupling coefficient directly affects the peak loss of the grating transmission spectrum.

Abstract:For the field error calibration problems of electronic voltage transformer (EVT) and electronic current transformer (ECT) in smart substation, field calibration methods of EVT and ECT were proposed on the basis of voltage and current comparative methods. The proposed field calibration methods used the communication protocol IEC 61850.Using a 110 kV smart substation as the background, the distribution of EVT and ECT was analysed respectively,and the operation methods of primary devices were described by using the proposed field calibration methods. By studying the working principle of the proposed field calibration methods, the secondary basic principle and working mechanism of the proposed method were studied. Meanwhile, the equivalent mathematical model of EVT's field calibration method was established. The field results not only demonstrate the effectiveness and accuracy of the proposed method, but also show that the tested EVT can be used as 0.2 level power meter transformers and the tested ECT can be used as 0.2S level power meter transformers.

Abstract:The inactivation effect of chloramine, chlorite for ammonia-oxidizing bacteria and heterotrophic bacteria was compared by using rotating annular bioreactors (RAB), which were applied to simulate the drinking water distribution system. The experiment results showed that 1.5 mg/L chloramine had a higher inactivate rate to AOB in bulk water (5.7×10-2 log/h) than in the biofilm (4.8×10-2log/h) during 24 h. Compared with chloramine, 0.6 mg/L chlorite had a much higher inactivation rate to AOB in the biofilm (6.4×10-2log/h) and bulk water (7.2×10-2log/h). Chlorite and hybrid of chlorite and chloramine disinfection had almost the same inactivation efficiency, and chlorite had no inactivation effect on heterotrophic in the biofilm and bulk water. The inactivation rate of chloramine on heterotrophic bacteria was 8.3×10-2log/h and 5.5×10-2log/h respectively. Based on chlorite inactivation effect on AOB and chloramine on heterotrophic bacteria, the hybrid disinfection of chloramine and chlorite on the controlling of nitrification was put forward.

Abstract:For the ill-posed environment hydraulic inverse problem, a methodical model was constructed based on Bayesian inference and two-dimensional water quality model. Markov chain Monte Carlo simulation was applied to get posterior probability distribution of the source's position, intensity and event init time. The result of case study shows that the method based on Bayesian inference with Markov chain Monte Carlo simulation is fit for inverse problem such as contamination event source identification featuring high accuracy and little error. Compared with the identification results of hybrid genetic algorithm and pattern search, the presented approach indicated high stability and robust on the same inverse problem.

Abstract:In order to improve accuracy of vertical handoff and to decrease connection dropping in heterogeneous wireless networks, a vertical handoff scheme was presented. This scheme improves the RSS-based handoff trigger mechanism and adopts the fuzzy logic-based normalized quantitative decision algorithm to determine the optimal handoff target network from all available access networks. To verify the feasibility of this approach, a heterogeneous network comprising UMTS and WLAN was used in simulation. Numerical results have demonstrated that the proposed approach outperforms other ones in the number of vertical handoff and handoff dropping rate while choosing effectively the optimum network by making trade-off among the user preference, network condition and system performance.

Abstract:This paper clarified the basic idea of structure 19 orders Steiner triple systems. The definition of edge matrix was given,which can be decomposed into complete graph and complete triple graph.Then the complete graph and complete triple graph can be decomposed respectively to obtain Steiner triple systems. Based on the Kv sub graph decomposition,the enumeration method and construction method of Steiner triple systems were given.And two methods were used to give the specific construction processes and count of 19 orders Steiner triple systems. It can be concluded that the construction method and enumeration method of Steiner triple systems are effective.

Abstract:Fuzzy congruence on lattices was proposed, and then the rough fuzzy sublattice was proposed.This paper focused on the rough fuzzy sublattices and investigated their properties in detail. At last,after introducing fuzzy relational morphisms between lattices,this paper has proved that they preserve upper rough approximations.