Abstract:Iced accretions on stay cables may result in unstable vibration of galloping, which affects the safety of cable-stayed bridges. Firstly, six kinds of stay cable models with iced accretions were manufactured with a geometrical scale of 1∶1, and wind tunnel tests were carried out to obtain the mean lift and drag coefficients. Galloping coefficients were then analyzed to estimate the possibility of galloping. Secondly, CFD simulations were conducted on two kinds of models with iced accretion, and the results were compared with those from wind tunnel tests. The results have shown that galloping takes place because the galloping coefficients are less than -10, and the results between wind tunnel tests and CFD simulations have very good agreement.

Abstract:From the frequency characteristic equation of a beam fixed and hinged at both ends, the frequency relationship between the two states was discovered, and a simple practical formula in the estimation of cable tension was proposed, which has definite physical meanings. The results from case studies have demonstrated that the formula can simulate the tension condition precisely for cables, so it can be used to identify the tension of cables with different slenderness ratios and flexural stiffness more easily and accurately. The influence of different cable boundary conditions on the cable tension calculation results was analyzed, and a cable tension formula which can take into account the rotational stiffness of the cable ends was proposed.

Abstract:A numerical study on the kinematic responses of pile-raft foundation subjected to vertically propagating S-wave seismic excitation was presented. The dynamic soil-pile-raft interaction was modeled by using the thin layered element method and the finite element method. The effective input motions of pile-raft foundation were expressed with dimensionless horizontal response factor IH and rocking response factor IR, which were the ratios of raft motions to free-field soil surface motion. The horizontal and rocking response factors of pile-raft foundation were compared with those of pile group and raft foundation. The effects of pile lengths, spacings and rigidities on kinematic response factors of pile-raft foundation were also studied. The results have shown that the neglect of the effect of the raft can result in too small an evaluation of the kinematic response factors of pile-raft foundation when the pile spacing is relatively large.

Abstract:Based on the vertical static test of two prestressed steel reinforced concrete frames，their characters, including failure pattern, crack development, rigidity change and moment redistribution, were investigated.The test results have shown that prestressed steel reinforced concrete frame beams,similar to under-reinforced concrete beams, are ductile failure; plastic hinges appear and plastic redistribution of internal forces is achieved on the frame beam end; and the ductility ratio of displacement is greater than 3. Moment redistribution values are about 30%, which is higher than ordinary prestressed concrete structures. The generation nature of secondary forces was analyzed and the calculation formula of ultimate flexural load-carrying capacity, crack resistance, stiffness and maximum crack width were presented, which consider secondary internal forces, including secondary moment and secondary axial force. The calculation results agree well with the test values. The calculation theory in this paper reflects new ideas of modern prestressed design and can provide reference for the establishment of “Prestressed Concrete Structure Design Code”.

Abstract:Cracks in autoclaved fly ash brick masonry walls are chiefly caused by the drying shrinkage of masonry during the service stage. A prediction formulation of the drying shrinkage of orthogonal masonry was derived on the basis of the mechanics of composite materials. The analysis results showed that the drying shrinkage of masonry could be approximately represented by the drying shrinkage rate of brick in masonry during the service stage, and the effect of the drying shrinkage of mortar on that of masonry was negligible. The effect of test methods, the moisture content, relative humidity, and the ratio of volume/exposed area on the drying shrinkage of autoclaved fly ash bricks was studied. It was showed that the drying shrinkage of autoclaved fly ash brick in RAPID method was smaller than that in SLOW method, and increased with the relative moisture content, decreased with the relative humidity and the ratio of volume/exposed area of brick. The prediction formulation of drying shrinkage of brick in masonry was obtained through the experiment results. The drying shrinkage of 6 masonry walls with different relative moisture contents in different relative humidity was measured, and the theoretical results was in good agreement with the test value.

Abstract:The structure and aerodynamic performance of the micro-turbine for the micro-machine tool spindle were designed and calculated, and the high speed airflow in the micro-turbine was numerically simulated by the software FLUENT. The analysis has indicated that the micro-turbine torque produced by airflow pressure changes little while that by air viscosity decreases dramatically with the increase of rotational speed at constant supply pressure, which causes a dramatic decrease in the total torque. The back pressure in the micro-turbine chamber increases with the increase of the supply pressure, which seriously affects the rotational speed. The airflow from the micro-turbine nozzle cannot directly go to the corresponding blade, but goes round the blade wheel under the action of the coming flow, which causes great flow loss. Finally the micro-turbine structure was improved and its torque increased by 13%,which satisfied the design requirement.

Abstract:The problem of elastic antiplane with a parabolic crack was investigated. The exterior region of the parabolic crack was mapped out of a unit circle through conformal transformation. A boundary integral method was proposed to avoid the difficulty caused by the singularities of the transform function. The complex potential solution to the elastic antiplane boundary value problem with a parabolic crack was obtained. The stress intensity factor (SIF) at the tip of parabolic crack was thus given by employing a formula proposed in the present article to calculate SIF directly on the basis of complex potentials. The solution can be reduced to the solution for line crack in a special case. The shape of the parabolic crack and the ratio of the shear stress loads of two directions at infinity affect the magnitude of stress intensity factors.

Abstract:A new autonomous hyperchaotic system was proposed. The chaotic system mainly relies on a nonlinear quadratic hyperbolic cosine term and a quadratic cross-product term. The basic dynamical properties of the system were studied by means of numerical and theoretical analysis. Moreover, a synchronization method for the new hyperchaotic system was established to synchronize the two non-identical chaotic systems asymptotically and globally. The nonlinear terms in the drive system were not dropped. Numerical simulations are provided to show the effectiveness and feasibility of the methods developed.

Abstract:The offset voltage of the OP directly influences the precision of the output voltage reference. To cancel the offset voltage, this paper adopts NPN to produce ΔVbe and designs a new feedback loop structure to produce a low voltage bandgap reference. The circuit is designed in SMIC 0.18 μm CMOS process. The temperature coefficient of this low voltage bandgap reference is 8 ppm/℃.The PSRR is -130 dB and the design output voltage is 0.5 V. The circuit has been successfully applied at a high speed, 16 bit ADC.

Abstract:Based on prokaryotic expression vector pCold TF, a new vector pL118 was constructed by replacing the His-Tag sequence of the original vector with the restriction enzyme site of Spe I in molecular biological methods. His-Tag sequence was introduced to the 3′ end of target gene through PCR primer, and this method facilitated the expression of fusion protein and the removal of solubilization tag from the target protein. The fusion protein human CD81-Trigger Factor (TF) was expressed and purified. Human CD81 protein was obtained by removing the TF solubilization tag by proteinase Factor Xa. The purified human CD81 protein laid the foundation for the selection of targeted drugs, making antibody and exploring the function of CD81. The construction of the new expression vector pL118 and the expression and purification of human CD81 protein have provided a new method for obtaining insoluble protein based on the prokaryotic expression system.

Abstract:Simulated weathering experiments on crude oil were carried out to investigate the changes in the fluorescence fingerprint characteristics of crude oil caused by weathering processes. The excitation-emission matrix fluorescence spectra of crude oil were analyzed in the peak-ratio method and principal component analysis. The research results showed that weathering had no effect on the fluorescence spectra fingerprinting characters, but had effect on the relative intensity of peaks, whose changing direction was determined by peak location. Changes of the peak intensity ratios and the score of Principle Component 1(PC1) were separated in two stages (on the water surface or in the water), which might be brought about by different weathering mechanisms. Peak intensity ratios and the score of PC1 could be simultaneously used to determine the extent of weathering in oil fingerprint identification.

Abstract:Analytical methods based on mass balance were adopted in the experiment to trace the carbon source distributed and utilized in a pilot scale system. The key parameters of carbon source distribution were investigated and the optimum operation strategy for urban sewage treatment plants was built. In the conditons that the influent concentration of the COD, NH+4-N, TN and TP were 129 mg/L，25.6 mg/L，31.5 mg/L and 3.38 mg/L, respectively, and the C/N and C/P value were 4.3 and 39.5, inverted A2/O process was recommended in winter period, enhanced A2/O process was recommended in spring period, pre-anoxic inverted A2/O process was recommended in summer period and alternating oxygen concentration inverted A2/O process was appropriate in autumn period. In this case, the ratio of effluent COD to influnent COD was 26.1%～29.4%, the ratio of assimilating COD was 27.5%～36.2%, the ratio of directly oxidating COD was 4%～22.2%, the ratio of denitrificating COD was 14.8%～33.6%, and the ratio of COD utilizing for removal was 3.05%～6.9%. The effluent of the pilot scale reactor could reach the standard of grade B, classⅠin Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002) apart from the concentration of phosphorus. The rationalization of carbon source utilization should be an important rule for the design and adjustment of wastewater treatment plants.

Abstract:Based on computational fluid dynamics Euler multiphase model, gas-liquid two-phase co-current upflow through packed bed was investigated. Tung & Siefken model, Schulenberg model and Attou k-fluid model were applied, respectively. The gas-particle, liquid-particle and gas-liquid drag force programs were implemented to CFD three-dimensional numerical simulation with user defined functions. A comparison of the experiment data has shown that Tung & Siefken's model was more suitable for the numerical simulation of gas-liquid two-phase upflow through porous media packed with 2~8 mm sphere under normal temperature and pressure. The CFD numerical simulated values of pressure drop and liquid hold-up by Tung & Siefken's model were consistent with the experiment results.

Abstract:In order to improve the accuracy and timeliness of fire detection and achieve the optimal utilization of existing hardware equipments, an automatic fire detection method with day-night infrared camera was proposed. Firstly, a video category classification algorithm based on IR frame color distribution in RGB color space was proposed. It can classify different videos and switch the detection state automatically. Then, fire candidate regions were extracted by using the fire color models of infrared state and visible state. Thirdly, the irregularity, corner number, frequency and correlation coefficient oscillation times were computed as four static or dynamic fire features. Finally, the training feature data optimized by Subtractive Clustering and Fuzzy C Means were the input of Neural Network,and fire classifiers for two kinds of video states were trained separately. Experiment results have indicated that the average classification accuracy of video categories has achieved 93.07%, and the proposed method is able to detect all of the 21 videos correctly. The proposed method gives warning 8 seconds after fire occurs. The processing speed is more than 25fps. It can meet the requirements of high detection precision, strong anti-interference, real-time processing speed, and adaptation to all-weather monitoring.

Abstract:Based on Genetic Programming (GP), this paper proposed an approach called Best Rule Genetic Algorithm (BRGA) for optimizing classification rule, and gained the best classification rule set. This algorithm can adjust relevant parameters of classifier model, substantially improve the performance of classification by increasing appropriate iteration, therefore it has considerable flexibility and intelligibility. The performance of the proposed approach was evaluated by using six gene expression data sets through simulation. From the result, it is found that the proposed approach reduces computational complexity and redundancy with good classification accuracy and stability than approaches reported in other literatures so far.

Abstract:The concept of derivation was introduced into Quantale theory. Firstly, the properties of the operation & of Quantale and the inclusion relation of the derivations of left (right, both)-sided were studied. Lastly, the properties of simple derivation were investigated.

Abstract:The existence of periodic solutions for a kind of p-Laplacian differential equation with two p-Laplacian operators was investigated. Based on Manásevich-Mawhin continuation theorem and some analysis skills, new sufficient conditions for the existence of periodic solutions were given. An example was provided to demonstrate the effectiveness of the proposed result.