Abstract:Based on the tests of 60 blocks chosen from 3 masonry walls at random, this paper studied the differences of the rebound value for different options of resiliometers and blocks with or without ribbed position. And through 9 comparison tests of hollow concrete block masonry specimens by rebound method, this paper analyzed the relationship of rebound value of the blocks under different constraints, vertical load and concrete grouted. Based on the comparison and analysis of the experimental data, a general calculation formula of compressive strength for common concrete hollow brick in existing masonry was put forward. Confirmatory experimental results have shown the high accuracy of this formula, which can provide a basis for the revision of relevant standards.

Abstract:A new reinforcement scheme to improve the ductility of common low shear-span ratio shear wall was put forward. In order to reveal the advantage of the new reinforcement scheme, an experimental study of the seismic performance of two different types of shear walls under cyclic loading was carried out, and their bearing capacity, hysteresis property, ductility and failure phenomena under reciprocating load were investigated. Based on the experimental study and ABAQUS software, the nonlinear performances of four shear walls with different reinforcement types were compared and analyzed systematically, and the locations of vertical seams were studied in the same method. The test results and finite element analysis have indicated that improving the ductility and deformation capacity of common low shear-span ratio shear wall by means of configuring concealed bracings or slotting and configuring steel plate are feasible. It has also shown that, compared with the low-rise shear wall with a common reinforcement scheme, the new type of low-rise shear wall shows greatly improved ductility, energy dissipation capacity and better seismic performance, and has multiple seismic fortification lines.

Abstract:Based on the study of the mix proportion of DSP(Densified Containing homogeneously arranged ultrafine Particles)for the sake of rock anchor grouting, the effects of water-binder ratio, volume of nanometer silica and different curing methods on the mechanical behaviors of the grouts have been investigated. A serial of appropriate proportion of DSP grout with good working performance were successfully found. The 48 h compressive strength in （80±2） ℃ hot water curing reached 127 MPa, the 7 d and 28 d compressive strength in standard curing reached 99 MPa and 120 MPa respectively, and the 7 d and 28 d compressive strength in underground natural cave curing reached 81 MPa and 109 MPa respectively.

Abstract:In order to set up a new detection method for the compactness of highway subgrade, the subgrade deformation and mechanics mechanism under static penetration were discussed with the nonlinear variation characteristics of the subgrade soil deformation. The idea with step-loading and the layer-wise summation analysis of ground foundation settlement was introduced with the Duncan-Chang model and the incremental generalized Hooke's law. Therefore, an analysis model between the subgrade penetration load and its displacement with the parameters about initial porosity ratio, Poisson ratio, cohesive strength and angle of internal friction was developed. On the basis of the static penetration displacement analysis model mentioned above, a method of back analysis based on the adaptive genetic simulated-annealing algorithm was recommended according to the subgrade static penetration load and displacement test curves, then a new detection technique for the compactness of subgrade based on static penetration was set up, which can not only detect the compactness of subgrade, but also check the other physical and mechanical parameters of the subgrade soil. And it still has the features with fast and efficient detecting. Moreover, by comparison with the other existing methods and the computation of an engineering example, the proposed method was proved to be reasonable and feasible.

Abstract:In order to confirm that the Large Eddy Simulation(LES) is applicable to the study of aerodynamics of bridge girder, the wind field around a box girder of a large span cable-stayed bridge, under Reynolds number of Re=1.27×105 in uniform flow, was accomplished by using three-dimensional Computational Fluid Dynamics(CFD) analysis. The LES employes the Smagorinsky subgrid turbulent model. Based on the grid and time step size independent check, the averaged drag, lift and moment coefficients, as well as the Strouhal number at various angles of attack, were obtained. The research shows that the vortex shedding is not synchronous in span-wise direction, and its energy is concentrated to a band including several peaks. Based on the distribution of mean and root-mean-square value of pressure around the girder surface, the flow separation and reattachment pattern on the girder surface were presented, and the reasonable arrangement of pressure taps on wind tunnel models was suggested. The results were compared with the results from wind tunnel tests. It is confirmed that the LES is capable of investigating the aerodynamics of bridge girders and flow mechanism.

Abstract:Wind effect of super high-rise buildings is closely related to its body shape, and the reasonable selection of the body shape is a prerequisite for the design or research of related wind-resistant work. In order to study the relationship between body shape and wind effect, the characteristics of existing super high-rise buildings were discussed firstly, by which a corresponding classification with separatrix of 350 m and 600 m was given. Then, the relationship between wind effect and aspect ratio, which may influence structural efficiency remarkably, was analyzed through several wind-resistant examples of high-rise buildings from the viewpoint of engineering practice and the basic theory of wind engineering. Finally, some preliminary proposals of body shape setting corresponding to buildings with different height, the aspect ratio and length-width ratio should be limited stringently to ensure the structure efficiency, and more considerations of rational building shape should be taken, were proposed.

Abstract:In order to study the influence of size and structure of non-smooth surface on vehicle aerodynamics, we took MIRA stepped-back model as the research object, and studied the aerodynamics of three different models by using CFD method and wind tunnel experiment. Compared with smooth surface, the principle of resistance reduction was investigated. Simulation results show that the resistance reduction effect of non-smooth units originally arranged at the trunk deck，the rear of the car and underbody, is best with the ratio of 5.90%. Non-smooth surface shows good ability to reduce model pressure drag through refining eddy of the rear of body. Meanwhile, air velocity and body frictional resistance were reduced by changing the air flow of the near wall.

Abstract:A new method to improve engine camshaft grinding efficiency and processing accuracy was proposed on the basis of maximum allowable angle steps. The angle step value was calculated from the local curvature of grinding wheel center motion curve relative to camshaft processing angle. Then, the cam was processed segmentally to optimize its processing angle step and speed. Compared with constant angular velocity grinding, this new method can reduce superfluous steps and increase manufacture efficiency. Moreover, it can also improve the processing accuracy and avoid the response lag on buffer portion linking to ascent portion and descent portion of cam.

Abstract:To deal with the existing problems such as lower flexible work reliability, speed limit in downstream machine caused by invariable pitch in the transferring device of high-speed bar stock, the working principle of a flexible transferring device with variable pitch was proposed, and the transferring process and the motion interference of the bar stock were analyzed. In order to improve the flexible transferring reliability of the bar stock, the multi-objective optimization of device's structure was presented. The results have shown that the axial braking process of the bar stock is improved, the transferring speed difference and the maximum pressure angle of the cam are reduced, and the rationality of optimization design is verified through simulation. The device has the advantage of accurate location, steady transferring, gentle axial braking process, and variable pitch, which is beneficial to the enhancement of production ability in downstream machine.

Abstract:Adhesion properties of piezoelectric viscoelastic microbeam were researched. A parameter named peel number was introduced to show the adhesion properties of the piezoelectric viscoelastic microbeam, the effects of piezoelectric voltage, viscoelastic parameters, and geometric parameters on peel number of the piezoelectric viscoelastic microbeam under adhesion were analyzed. The results show that, if piezoelectric voltage rises, the peel number will increase efficiently, which presents theoretical basis for repairing the adhering piezoelectric microbeam. The geometric parameters of the microbeam also show significant influence on the peel number, which will make a certain restriction on the design of MEMS and NEMS.

Abstract:This paper introduced a machine vision imaging system to acquire rail surface images based on line scanning, and presented an algorithm to detect rail surface defects accurately based on image enhancement and automatic thresholding. We proposed a local zero mean measure to enhance rail images, which can overcome the nonuniform reflection of the rail surface and improve the distinction between defects and background. And then, we put forward a proportion emphasizing maximum background-class variance measure to select a threshold, which maximizes the background-class variance and meanwhile keeps the defect proportion in a low level. Through experiments, we compared the core of the algorithm with well-established methods, and then proved the validity and rapidity of the algorithm with wide applicability.

Abstract:In order to enhance transformer fault classification accuracy based on dissolved gas analysis (DGA) and overcome the limitations of single subspace, a new transformer fault multilayer diagnosis model based on dual-space feature extraction algorithm was proposed. Firstly, a DGA test sample was projected to a subspace to realize feature extraction in order to reduce the dependence of the modeling accuracy on kernel function and parameters and take advantage of stronger robustness and higher precision. Multiple-kernel support vector machine (MKSVM) was used as the classifier to predict the class label. The test sample was classified into difficult class one or easy class one according to the predicted result, and the class label of the easy one was identified in the subspace directly. As to the difficult one, the test sample was re-projected to another subspace where multiple-kernel support vector machine was used to predict. The class label of the difficult was identified to integrate two predicted results. Therefore, MKSVM of two class problem based on dual-space feature extraction algorithm was achieved. Finally, a multilayer diagnosis model was established according to the fault characteristic of transformer. The diagnosis experiment has shown that the model has a higher diagnosis rate, which proves its effectiveness and usefulness.

Abstract:To solve the problem that the existed scheme of synchronized control of multi-motor is difficult to meet the requirements of high precise synchronized control and the limitation that it can not achieve proportional synchronized control, a belt PI compensative control of the improved Relative Coupling Control structure was proposed, which can apply to completive synchronized control and proportional synchronized control for multi-motor. As to the problem that the Permanent Magnet Synchronous Motor (PMSM) is a multivariable nonlinear system with strong coupling, an adaptive fuzzy sliding mode controller was designed to control the PMSM. The synchronized control simulation mode of four PMSM was set up. Compared with fixed gain compensative control structure, simulation results illustrate that this new structure has higher synchronized control accuracy. Compared with PID and conventional sliding mode control strategy, this fuzzy sliding mode control strategy has a better synchronized stability behavior and stronger robustness.

Abstract:Fine-grain magnesium alloy sheets possess high strength and excellent ductility，and fine-grain AZ61 magnesium alloy sheets of 2.0 mm in thickness were welded with CO2 laser beam with filler metal and without filler metal. The weldability of fine-grain magnesium alloy sheets and the effect of the rare-earth element Ce in filler on fusion zone microstructure and mechanical properties were investigated. The results indicated that the rare-earth element Ce could refine microstructure, so that the grain size of joint without filler was much larger than that with filler and the former was about 15 μm and the latter was about 5 μm. Also, columnar dendritic grain range was restrained and equiaxed dendritic grain range was expanded resulting from the rare-earth element Ce. Additionally, there was little difference between heat affected zone (HAZ) and base metal and the extent of liquation in partially melted zone (PMZ) was low, and the range of HAZ and PMZ was narrow, which showed that the weldability of fine-grain AZ61 alloy sheets was good . The ultimate tensile strength and elongation of the weld with filler metal are 6% and 12% higher than the weld without filler metal.

Abstract:High-speed steel wires M42 and high strength steel strips X32 were welded on the band saw blade by using CO2 laser. The typical microstructure of welding joints，the distribution of elements,and the influence of different bonding technologies on welding joints microstructure and mechanical properties were studied by using metalloscope, electron microscope(SEM), microhardness meter and electron probe(EPMA). The results showed that isometric increased , dendrite decreased in the weld center and isometric near the side of M42 fusion boundary area became more fine with the increase of welding speed. The hardness of the welding joints in every bonding technology was higher than parent metal. Moreover, the hardness of the bond area near the side of M42 was higher than the welded zone's. When the welding power was 2 754 W and the welding speed was 14 m/min, the property of the welded joints was good, and the value of bending strength reached 112 MPa, which reached the requirements of double metal band saw blade welding.

Abstract:Based on the block-level sensor pattern noise (SPN), a video forensics scheme, whose adaptive-threshold is obtained by maximum likelihood estimation, was proposed. It extracts the SPN by wavelet de-noising and Weiner filter. By setting a sliding window of fixed size, block-based energy gradient, signal-noise ratio and the correlation between the SPN of blocks with the same positions in neighboring frames are computed to build a feature vector. The maximum likelihood estimation is utilized to obtain the adaptive threshold of classification. Experiment results show that the proposed approach is effective for the forensics of copy-paste based tampering to the contents of digital video. Moreover, it can locate the tampering of small regions in digital video.

Abstract:State-of-the-art cross collections topic models suffer from major flaw that they can only analyze the common topics among document collections. We introduced a mixture model PCCMix (Partial comparative Cross Collections Mixture) for multi-collections CTM to detect both common topics and collection-special topics. PCCMix divides the two types of topics in document collections by estimating a probability distribution from the whole dataset in advance, and then trains the model by the Expectation-maximuzation algorithm (EM). Experiment results show that PCCMix can analyze both common topics among collections and collection special topics. The PCCMix model is very effective and can model the document collections more precisely than the two main CTM models.

Abstract:To deal with the interception performance of the spaceborne sensors with narrow field of view in low earth orbit constellation, a simplified interception probability calculation method was proposed based on Gauss ellipsoid of the guided information error, according to the analysis of the field of view of the sensor. Moreover, the calculation complexity and influencing factor of interception probability were analyzed. The simulation results indicate that the proposed calculation method could reflect the interception performance rationally and hasn’t operation burden. Furthermore, the influencing factor analysis could provide necessary references to the real application.

Abstract:From the perspective of resource integration, this paper analyzed the effect relationship between interaction and virtual community co-created value. Under the background of virtual community, this paper defined virtual community co-created value with the help of literatures and proposed the dimensions of virtual community co-created value coupled with qualitative research of focus group interview, including three dimensions of pragmatic value, hedonic value and customer equity. Meanwhile, this paper confirmed the relationship between interaction, resource integration, co-created value and customer loyalty with an empirical study of structural equation models. The results show that, with the help of resource integration, interaction between customer and service personnel as well as interaction between customer and customer can improve the achievement of pragmatic value, hedonic value and customer equity. Pragmatic value, hedonic value and customer equity have significant positive effect on customer loyalty.

Abstract:Patent collaboration network was used to denote the industrial innovation network architecture. Collaborative patents related to automobile industry for 1985 to 2009 from State Intellectual Property Office of the P.R.C(SIPO) were employed to UCINET6 to draw topology maps. The co-integration equations were constructed to test their impacts on network performance. The results have shown that cliquish technology collaboration is an important path to push innovation networks' development. It has long-term, steady and positive influence on the performance of industrial technological innovation, and this effect is more significant on the low-novelty innovation.