Abstract:In order to obtain the wind pressures on a sail-shaped building, the wind tunnel testing method was employed. The distribution characteristics of mean wind pressure and fluctuating wind pressure on the sail-shaped building were presented, and the causes leading to the distribution were analyzed. The most unfavorable region of the building under different wind azimuths was also investigated for the wind-resistant design of cladding structure. The results have shown that the wind pressure on a sail-shaped building tends to bear press on the windward face and suction on the leeward face, leading to unfavorable wind loading case for the sail-shaped building which has large area with small width. The distributions of mean wind pressure and fluctuating wind pressure on the building are mostly similar, and the fluctuation on the leeward face is usually smaller than that on the side wind zone. When the shape edges of the sail-shaped building are on the side wind direction, strong pneumatic separation will occur, resulting in significant negative wind pressure on the edges.

Abstract:Due to structural stiffness characteristics, there are essential differences in the dynamic behaviors and responses between large-span spatial structures and traditional multi-storey or high-rise buildings. Therefore, it is difficult, sometimes even impossible, to calculate the earthquake responses of spatial structures with the traditional mode superposition of response spectrum method, since the mass participation factors always accumulate very slowly. Aiming at the deficiency of the method, the dynamic characteristics of spatial structures were investigated. The essential characteristics and the deformation mechanism of earthquake responses of spatial structures, including the distribution law of vibration modes, were revealed and concluded. Based on the definition of mass participation factors (MPF), the principle of vibration mode truncation and the mutual theoretical relation of both, a new simplified method for the dynamic computational models of large-span spatial structures was proposed. Then, numerical analysis of a numerical example was conducted to verify this method. The numerical results have indicated that the new simplified method is effective, efficient and accurate for the earthquake response analysis of large-span spatial structures.

Abstract:This research improved the frame structure and advanced the energy-efficient system of frame structure with dual-beams, whose principles were introduced. The thermal performances of the beams and columns were also analyzed with fluent software by building a three-dimensional steady thermal conduction model. The results have shown that this system is energy saving by 59%, compared with frame system. The heat flow of the beams and columns has been reduced by 79%, which indicates that this system has a distinct energy-saving effect. With the cold and hot bridges reduced and a large area of the new wall materials used, there is no need to build outside and inside insulation, whose shortages are avoided. Because of these, this new system better meets the requirements of green ecological energy-efficient buildings.

Abstract:The accuracy of seismic response results significantly depends on the exactness of the Finite-Element Model（FEM）.This paper took a representative three span continuous bridge as an example. The methods for model different components and boundaries of the bridge were summarized and investigated systematically, and three approaches were adopted to establish three nominally identical bridge models. Then, the same seismic record was selected to conduct the time-history analysis, and the response results of the three models were compared. The numerical results have revealed that it is improper to evaluate the bridge seismic behavior with the traditional simplified model because of the error and impreciseness, and the results can hardly reflect the nonlinear response of the bearing, blocking and expansion joint,et al. However, this accurate model can reveal the accuracy and exact seismic response. In addition, it is even more adoptable for the performance-based bridge seismic design.

Abstract:This article presented the comparisons of two different testing methods and different curing conditions for heat deflection temperature（HDT）. The effects of curing condition, curing agent, diluent and toughener on the heat resistance performance of epoxy structural adhesive were studied by testing the HDT of epoxy structural adhesives, and an optimized formula of pressure injection adhesive for steel-bonding was found. The results have indicated that epoxy structural adhesive has good heat resistance performance and impact toughness by using rigid curing agent (such as modified alicyclic amines and phenolic amine), epoxy diluent with high functionality and the “island structure" toughener. The optimized adhesive has a HDT up to 65.9 ℃ and a T impact peeling length of 21mm , whose overall performance can meet all the requirements of structural strengthening.

Abstract:Based on the Euler-Bernoulli beam theory, a dynamical model of piezoelectric coupling beam subjected to axial force and delayed-feedback was derived. The stability conditions of the system under piezoelectric coupling and delayed feedback was investigated through modal analysis and linear stability analysis. The Galerkin method and multi-scale method were used to study the bifurcation response of the time delay system. Numerical simulation was employed to study the effects of control gain on the dynamics of the system, i.e., stability and bifurcation of an equilibrium point, periodic solution, period-doubling, quasi-periodic motion and even chaos.

Abstract:The burnout of zinc is one of the key problems in laser welding of galvanized steel. In this paper, the burnout width of the zinc layer on both the top and the bottom of the weld and the zinc content in the middle layer of the weld zone were measured, and the weight gain ratio after the corrosion tests was obtained. The relationships between process parameters and the spectral signals of the laser-induced plasma as well as the burnout of the zinc were experimentally studied in laser lap welding of galvanized steel. The results have shown that: 1) the important order of the relevant factors affecting the burnout of the zinc is welding speed>laser power>auxiliary gas flow> defocus; 2) the burnout rate of the zinc is increased with the increase of the intensity of zinc line Zn I 328.2 nm and Zn I 330.3 nm; and 3) pores are generated because of the evaporation of the zinc. The more zinc content exists around the pore wall, the larger the diameter of the pore is. The intensity of the zinc line can be used for the on-line monitoring of the dynamic rate of the zinc burnout and the pore produced in the laser welding process.

Abstract:A new kind of photovoltaic array simulator utilizing TMS320F2812 DSP as the controller and Buck circuit as the main circuit was put forward. The simulation algorithm controls the duty cycle of the electronic power switch in buck circuit by utilizing the difference of actual load current of the simulator and the characteristic current of photovoltaic array, and then adjusts the output voltage of the simulator so as to make the operating point of the simulator approximate the working point of photovoltaic array on the I-V characteristic curve. In DSP, the mathematical model of the I-V characteristic curve for the kind of photovoltaic cell array was stored. The characteristic current can be calculated by means of the model corresponding to different quantity of illumination (S) and ambient temperature (T). A lot of simulating and experiment results have shown that the simulator can simulate perfectly the I-V characteristic curves of photovoltaic array with outstanding performances. Its approximate and stable time is about a quarter of the time for traditional point by point approximate. The approximate error is lower by 4% and the overshoot is lower by 1%.

Abstract:This article introduced the principle and structure of on-line audio monitoring system for electrical equipment in non-attended power substation, then focused on data monitor and recognition. At first, the audio sensors collect the sound data of running electrical equipment of power substation, the audio data input to the monitoring host, and the monitoring host deals with the audio spectrum, analyzing the audio data and recognizing the fault by neural networks based on sine basis function, which can determine the operation status of electrical equipment and the type of fault quickly. Fundamentlly, this method can improve the previous artificial monitoring sound of electrical equipment to determine different type of error, and it also provides help for the timely maintainance and correcting the faults in power substation.

Abstract:This paper analyzed the power coupling problem caused by transmission line impedance of low voltage micro-grid transmission lines, which is different from traditional high-voltage transmission lines. And according to the two typical modes of microgrid, different control strategies were adopted to control the low-voltage microgrid. In grid connected mode, PQ control strategy was used with micro power sources to support the local voltage and adjust the feeder power flow of the low-voltage distribution network. In island mode, voltage/frequency (V/f) droop control was employed with micro power sources to ensure that power load can be quickly shared by each of them and hold the stability of the voltage and frequency. To match the inverter output impedance and the line impedance, resistive virtual impedance was introduced into the inverter control strategy. Based on the resistive characteristics of the low-voltage line parameters, the traditional high-voltage grid droop characteristic was amended, and through a coordinate rotating orthogonal transformation matrix, V/f droop control was improved, extending the traditional V/f droop control to low-voltage micro-grid. The simulation verification and analysis show that the integrated control strategy designed for the low-voltage micro-grid system can guarantee the stability and reliability of the system and its operation.

Abstract:An interior permanent magnet (IPM) brushless DC motor (BLDCM) for electric vehicles was designed, and the influences of the air gap length, the permanent magnet thickness and the number of stator winding turns on system efficiency and the torque-current ratio were analyzed. Comparative analysis of the performances at different load rates was implemented to consider the complex operating conditions of electric vehicles. An optimized prototype was fabricated and tested. The research results have shown that the reduction of the length of the air gap can improve the motor performance at low speed area on the premise of strong mechanical processing capability, the increase of the amount of permanent magnet can improve the overall performance of the motor, and the reduction of the stator winding turns can improve the motor performance at high speed area but at the same time will cause a drop in the torque-current ratio. The overall efficiency at rated speed is higher, showing that the design of rated operating point is reasonable. The torque-current ratio increases with the increase of load rate, and this is related to the reluctance torque component in the output torque, which is an important distinction between interior and surface permanent magnet motors and is also a noticeable problem in design. The test results have shown that the optimized prototype can meet the need of the driving system both in constant torque region and in constant power region.

Abstract:Epoxy resin was used as the reductant and solid-state reaction was applied to synthesize Li3V2(PO4)3 cathode for lithium batteries. The crystal structure and morphology of the sample were characterized through X-ray diffraction analysis and with scanning electron microscopy. Galvanostatic charge-discharge and cyclic voltammetry were utilized to determine the electrochemical properties of the sample. The results have shown that the synthesized Li3V2(PO4)3 possess a well-developed monoclinic crystallite structure. Its particles distribute uniformly and the size is small. The initial discharge capacity is 126.9 mAh/g at the 0.2 C rate in the voltage range of 3.0~ 4.3 V. The discharge capacity is 126.0 mAh/g and the capacity retention rate is 99.29% after 30 cycles.

Abstract:Carbon nanotubes (CNTs) functionalized with various surface functional groups were introduced into the fabrication of binder for metal injection moulding. Scanning Electron Microscopy (SEM) micrographs indicated that the functionalized carbon nanotubes were homogeneously dispersed in binder matrix. The polarized optical microscopic photographs and thermal analysis results have shown that the addition of CNTs can not only effectively improve the crystallinity and thermal stability of the binder, but may also increase the green strength of injection sample. The non-covalent bond between carbon nanotubes and polyethylene contributed to the uniform dispersion of the carbon nanotubes and the debinder of the composite.

Abstract:The availability of diversified germplasm resources is most important for developing improved rice varieties with higher seed yield and other desired agronomic traits. In this study, the effect of subculture time, 2,4-Dichlorophenoxyacetic acid (2,4-D) concentration and variant explants on the frequencies of plant regeneration and mutagenesis were investigated, and a new somatic mutagenesis breeding method for rice with the immature inflorescences as explants, 3 cycles of subculture time (about 75 d) and 4.0 mg/L 2,4-D as the preferred mutagenic concentration was developed. Then, the parents of hybrid rice, Zhu1S and Zhong 9B, were mutagenized in this new method, and 2 elite semi-dwarf somatic lines, SV14S and SV9B, were successfully isolated, which will provide high-quality germplasm resources for follow-up cross-breeding. The breeding achievements made in this study further confirm that this rice somatic mutagenesis breeding method is a simple and effective breeding method.

Abstract:Codes obfuscation is one of the main methods to hide malicious codes. This paper proposed a new dynamic method to effectively detect obfuscated malicious codes. This method used ISR to conduct dynamic debugging. The constraint solving during the debugging process can detect deeply hidden malicious codes by covering different execution paths. Besides, for malicious codes that read external resources, the detection of abnormal behaviors can only be detected by taking the resources into consideration. The method proposed has better accuracy by locating the external resources precisely and combining it with the analysis of original malicious codes. According to the test result of 12 anti-virus softwares, this prototype system can noticeably decrease False Negatives rate in the detection of obfuscated malicious codes.

Abstract:In order to adapt the actual application requirements, sensitive-level functions, perfect integrity labels of subjects and objects were added in the traditional Biba model. Also its safety operation rules were improved. The elements, the invariants and the transition rules of the improved model were described in completely formal methods. By doing this, the model was automatically formal verified by using theorem-prover Isabelle. The formal description and formal verification satisfied the formal methods requirement in the development of high-level secure operating systems.

Abstract:One type of noise barrier was chose as subjects, and the realistic simulation circumstance was constructed based on the distribution features of noise sensitive points near the proposed highway. Then, the prediction model of noise-reduction effects of noise barrier was built by Cadna/A software, and by utilizing this model, the parameters of this type of noise barrier were optimized. The research results revealed that this type of noise barrier can not only decrease the noise value of sensitive points to reach the environmental standards, but also minimize the construction cost when the right side noise barrier is 440 meters in length and 3.6 meters in height, and the left side is 400 meters in length and 4.4 meters in height.

Abstract:A probabilistic environmental quality assessment method of soil heavy metals based on Monte-Carlo simulation and index of geoaccumlation was developed by considering the data screening and weighting system of different heavy metals' biology-toxicity. Then, a case of contaminated farmland soil was put forward to test and verify the feasibility of the proposed method. Then, by building the factor probability distribution models of the sample content parameters and corresponding background value parameters, the probabilistic quality assessment method was applied with the preferences of maximum number of trials 1000, confidence level 95% and Latin hypercube sampling method. The results showed that the pollution degrees of these heavy metals were in the order Cd＞Ni＞Zn＞Cu＞Cr. The pollution degree of Cd belonged to the probability of serious pollution level as high as 98.1%. Ni and Zn were in spatial distribution of a clear difference, and belonged to the probability of serious pollution level at 84.5% and 87% respectively. Cu and Cr were relatively low in pollution level. At last, through a comparative analysis, the results showed that the proposed method owned a higher resolving property, and could express their corresponding probabilistic risk levels, which provided a basic theory to scientific decision-making.