Abstract:A series of spring-suspended sectional model tests were carried out to investigate the soft flutter phenomena for four typical bridge deck sections including a flat full-closed box section, a centrally-slotted box section, a semi-closed box section and a twin-side-girder section, which are all common in bridge engineering. The test results show that soft flutter is a single frequency vibration coupled with torsional and vertical degree of freedoms (DOF) and could be observed in the wind tunnel tests of the four typical bridge deck sections under investigation. The degree of the above-mentioned torsional-vertical coupling varied with wind speed, and can be enhanced with the improvement of the streamlining of bridge deck sections. Generally, the bluffer the deck section is, the wider range of wind speed the soft flutter will cover. The adding of accessories on bridge decks will enhance the vibra-tion response of soft flutter. Whereas, changing structural damping ratios has a limited influence on the soft flutter phenomenon.

Abstract:Four tall reinforced concrete columns with box section were tested in static cycle loadings and multi-level performance was investigated. The entire progression of cracking was monitored by using clip-on gage and then residual cracking damage was explored. It shows that cracks measured after the specimen was totally re-centered following a displacement cycle would substantially underestimate residual crack damage. An extra discount on the strength demand could be obtained if allowing a tiny residual crack that requires no repair work. Concrete crushing and spalling were also investigated in the test, and similiar experimental results were selected from the PEER datebase and also from some literatures. The samples showed a well concentrated distribution in lateral drifts at the onset of concrete crushing, about 2.39 percent on average, which is quite consistent with the present tests. Finally, all the specimens were found failed from fracture of the longitudinal reinforcement. The equations proposed by Prestely and by Berry were compared in predicting of the ultimate displacement capacity, and the results show that the equation presented by Berry yielded better results for the specimens.

Abstract:The seismic behavior of solid-web steel reinforced concrete (SSRC) cross-shaped column was investigated through low cycle reversed loading experiment of 4 column specimens with various axial compression ratios, steel ratios and loading directions. The failure process and pattern, load-displacement hysteretic curve and skeleton curve of columns together with ductility were analyzed. The experimental results show that the failure mode of SSRC specimens with large shear span ratio is bending failure. The hysteretic curves are relatively plump. The displacement ductility coefficients are larger than 3. The drift ratios vary from 1/28~1/16. Furthermore a finite element analysis (FEA) considering the interfacial bond-slip between steel and concrete was carried out to simulate the influence of different parameters including axial compression ratio, steel ratio and loading direction on SSRC bearing capacity and ductility. The numerical analysis results agree well with the experimental results. FEA and Test results indicate that SSRC have favorable ductility and plastic deformation, and can be adopted in the construction of high-rise buildings in high seismic fortification zones.

Abstract:Considering the nonlinear characteristic of the shear strength of the municipal solid waste and based on power form function, a nonlinear strength criterion in p-q stress space was proposed. According to the proposed criterion, the friction angle corresponding to the linear Mohr-Coulomb criterion was obtained, and it was shown to decrease with the increasing of the initial confining stress. By adopting the incremental hardening rule and suitable plastic potential function, a non-associated elasto-plasticity model for the MSW was built. By predicting a series of consolidated drained triaxial tests of MSW, the proposed model was shown to be able to predict the stress-strain relationships of MSW rightly and could give out reasonable prediction of the volumetric strain.

Abstract:In order to develop the calculation method for the tensile strength of headed studs widely used in steel-concrete composite bridges, four groups of pull-out specimens with different stud heights were tested. The overall stud heights used in the four groups were 100mm, 200mm, 300mm and 400mm, respectively. Based on the test results, the effect of stud height on failure mode, tensile strength and peak separation were investigated. Tensile strength equations specified in exiting codes (ACI 318-08, PCI 5th and CEB-ECCS) were evaluated based on 93 test data of this study and other researches. In addition, constraint equations for preventing the brittle failure modes of stud pullout, side-face blowout and concrete breakout were developed. Finally, calculation method of the ductile tensile strength of headed studs was proposed. The results indicate that the tensile strength and peak separation of the specimens failed due to steel failure are 1.5 times and 5.8 times as large as those of the specimens failed due to concrete breakout failure, respectively. The strength equations given by ACI 318-08 give more accurate predictions than those in the other codes. The minimum concrete compressive strength, minimum distance from stud center to concrete edge and stud height-diameter ratio are employed as constraints to prevent the brittle failure modes. The proposed calculation method of the ductile tensile strength of headed studs can provide guidance when designing headed studs under tension force.

Abstract:Aiming at the well resistance during the consolidation process of composite ground with stone columns in practical engineering, the causes of well resistance and the time and space effect under variable well resistance condition were analyzed. The equations for the consolidation of composite ground considering time effect of well resistance were established by analytical method. Based on the variation of permeability coefficient of the stone column, two types of functions which describe the relationship between permeability coefficient and time were built and the general analytical solutions are derived under the specific variation modes for the consolidation problem of the composite foundation with stone columns. The results show that the variation of well resistance has obvious influence on the consolidation rate of the composite ground with stone columns. Compared with the existing theories, the results of this paper are more reasonable. In addition, the larger the initial value of well resistance factor, the severer the influence of the time effect of well resistance. In order to accelerate the consolidation of the composite ground, it is more efficient to improve the permeability rather than the modulus of stone columns under the same conditions.

Abstract:The true triaxial test results for unsaturated soils indicated that the intermediate principal stress affected the unsaturated soil strength significantly. However, most existing strength formulae of unsaturated soils were based on the Mohr-Coulomb strength criterion and did not consider the intermediate principal stress effect. On the basis of the new twin-shear strength criterion of Mao-Hong Yu and the two stress state variables theory, a new twin-shear true triaxial strength criterion is derived and validated by the rigid and flexible true triaxial tests of unsaturated silty sand available in the literature. It is shown that the new piecewise linear twin-shear true triaxial strength criterion proposed in this study can reflect strength characteristics of unsaturated soils, such as the effect and its range of intermediate principal stress and strength differences among uniaxial tension and uniaxial compression; the new twin-shear strength criterion can be a linear approximation of the extended nonlinear Spatially Mobilized Plane criterion; neither the Mohr-Coulomb strength criterion nor the circumscribed Drucker-Prager criterion has good applicability to true three dimensional stress states and test data of unsaturated soils, in that the predictions of Mohr-Coulomb strength criterion are small, whereas the predictions of circumscribed Drucker-Prager criterion are obviously large.

Abstract:Influence of the hydration heat by cement on the ground temperature around the ground heat exchanger was investigated by numerical simulation and field measurement for ground temperature. Influence of the ground temperature around the ground heat exchanger on the heat transfer effect in ground heat exchanger was investigated by theoretical analysis, heat transfer experiments of ground heat exchanger, and numerical simulation. Researches on the ground heat exchanger in Shanghai Museum of Natural History shows that the ground temperature approximately 10 m below the basement floor is most affected by the hydration heat of cement, and the average ground temperature 2.85 m away from the underground diaphragm wall increases by 2.2℃, when the ground source heat pump system is initiated. The heat transfer rate in ground heat exchanger decreases linearly with the increase in initial ground temperature in summer; Moreover, the heat transfer rate in the ground heat exchanger decreases by more than 5% in summer when the ground temperature around the ground heat exchanger is 1℃ higher. Measures should be taken to the ground heat exchangers whose distances between the underground diaphragm wall are no more than 13 m to ensure an efficiently operational heat transfer system, when the system is initiated in summer.

Abstract:Extreme extrapolation methods are critical to predict the extreme value of long-term load response on the base of traffic data acquired in a short time. In this paper, a review on the extreme extrapolation methods in the fields of traffic load research is presented. Several main extrapolation methods are introduced in current applications. Analysis on the key parameters, including basic data and bottom distribution, is performed with consideration to their influence on extrapolated extreme values. A detailed comparison between empirical extrapolation method and maximum extrapolation method is also provided. The research results suggest that the key of extreme extrapolation of traffic load response is the description of tail data tendency of the bottom distribution. Length of the measured data which would be adopted for extreme extrapolation should be at least 21 days to provide a reliable reflection on the practical situations. The empirical extrapolation method is credible in a way when the reliability standard problem is answered. The maximum extrapolation method is very accurate and efficient under the circumstance of basic data with large capacity. The extrapolation method based on level crossing method not only needs to search for the optimum fitting starting point, interval and goodness-of-fit test method, but also significantly depends on the selection of empirical distribution including Rick Formula.

Abstract:Improper combination between highway horizontal and vertical alignment is one of the main reasons of dangerous segments, which easily leads to traffic accidents, such as speeding, rear-end collision, rollover, and emotional stress. They often are shown as broken back curve, inadequate sight distance and lack of beauty in drivers' visual. This is mainly due to a large deviation between visual perception and the actual supply from highway horizontal and vertical design, especially horizontal information even more so. In this paper, the index of the visual horizontal component was used to describe the deviation between visual horizontal perception and the actual supply and a new analysis technique to evaluate the coordination between highway horizontal and vertical alignment was studied. Firstly, the model of centerline in highway perspective view was built based on CatMull-Rom spline, the centerlines of actual perception and horizontal datum in highway perspective view were proposed based on the perspective principle. Secondly, based on front study, the method of calculation driver's perception horizontal deviation according visual reconstruction was put forward and the causes of perception deviation was also analyzed simultaneously. Finally, the horizontal and vertical coordination classification thresholds were determined using interval estimation methods based samples in the past used to evaluate the coordination between highway horizontal and vertical design, the results could provide technical support for research on horizontal and vertical coordination assessment.

Abstract:A 2D hydrodynamics and pollutant transport model was firstly established, and the model was verified well by the field measured hydrodynamics and water quality data in 2011. Based on this model, the features of hydrodynamics and pollutant transport during a spring tide in the flood season in Qinhuangdao coastal water were studied. Furthermore, the influence of wind on hydrodynamics and pollutant transport in Qinhuangdao coastal water was analyzed. Numerical results show that the main direction of the ebb current is northeast, while the direction of the flood current is southwest. The water level of Qinhuangdao coastal water will slightly decrease under the influence of summer wind in Bohai sea. Meanwhile, the current velocity will decrease in the northern coastal water of Shihe River estuary and increase in the southern coastal water of Shihe River estuary at the slack of ebb, while the current velocity will slightly increase in the northern coastal water of Shihe River estuary and decrease in the coastal water between Daihe River estuary and Luanhe River estuary at the slack of flood. The direction of COD transport is accord with the direction of tidal current. The COD concentration will decrease in the southern coastal water of Luanhe River estuary and increase in the northern coastal water of Yanghe River estuary at the slacks of ebb and flood.

Abstract:Quantitative research based on carbon accounting is the key of low-carbon campus construction and management. The achievements of Intergovernmental Panel on Climate Change (IPCC), World Resources Institute (WRI) and China Youth Climate Action Network (CYCAN) were integrated to develop a new method on energy-related carbon accounting in campus, which was then applied to the analysis of energy-related carbon emission in one of the university in Shanghai. The results showed an increasing trend of carbon emission from 2004 to 2012, with an average annual growth rate of 5.75%. Carbon emission in 2012 was 41112 ton CO2-eq, in which electricity-related emission accounted for 68.7%, and gasoline-related emission accounted for 25.0%. This study compared the low-carbon campus constructions in China with those abroad and showed that the integral and achievable low-carbon planning is likely to lead to a significant decrease of CO2 emission in western countries. Low-carbon in campus was redefined as a lower-carbon condition with continuously improvement and high energy efficiency compared to the baseline condition in campus. A low-carbon campus managing strategy was proposed based on energy-related carbon accounting analysis.

Abstract:With the rise of the global low carbon manufacturing，energy consumption and utilization rate of the machining process have drawn increasing attention, and energy consumption has gradually become an important index of the machining process decision. Traditionally, the energy required for the cutting process is estimated based on cutting force prediction equations, this estimation is limited to the energy consumption of the material removal process. This paper divided the energy consumption of the machining process into three parts: fixed energy consumption, no-load energy consumption and cutting energy consumption, an energy consumption estimation model is proposed, parameters are determined by experiments. Finally, an actual milling case is illustrated indicated that the model is able to provide a reliable prediction of energy consumption for given process parameters, which would be the foundation of the subsequent process parameters optimization and process decision.

Abstract:Firstly, new trends of research and applications of torque converters are overviewed in this paper. Then, the technology of measurement and numerical simulation of internal flow field, optimization and prediction of hydraulic performance as well as analysis of key design parameters of torque converters are discussed. Furthermore, the current research achievements are brought forth, such as parametric modeling of cascade system based on the non-uniform rational B-spline, modification of hydraulic prediction model based one-dimension flow theory according to the results obtained from computational fluid dynamic analysis and internal flow simulation in the turbomachinery based on the lattice-Boltzmann method. Finally, based on the current research achievements, the way to realize the technology of automated integration of cascade design and analysis is presented.

Abstract:Features of different power transmission paths of a novel fixed shaft active transmission were analyzed. From aspects of maximal velocity, ramp start capability and backup power, dynamic property requirements of different vehicle modes were given, the necessity of a new power matching design method was explained. According to backup power requirements, types and power ratings of power sources were selected. According to ramp start capability requirements and maximal clutch slipping work during ramp start, 1_st gear ratio was determined. According to maximal velocity requirements, drive motor power transmission paths ratios and remaining gear ratios were calculated. Structural features of EMT prototype and vehicle prototype were described, Based on NEDC, energy consumption test was realized. The methods to realize smooth drive torque at wheels during mode or gear switch was were explained in details.

Abstract:Refrigerant circuitry of the dual-system condenser in a roof-top air-conditioning unit was optimized using refrigeration system and CFD (Computational Fluid Dynamics) simulations. CFD simulation of airflow was carried out to obtain the frontal velocity distribution of the condenser. Refrigeration system simulation was used to design refrigerant circuitry of the condenser and predict the system performance. The proposed circuitry design was evaluated at both component and system levels. At the component level, results indicated a 24.1% increase on the heat transfer rate of new condenser in comparison with the original design. At the system level, the cooling capacity and COP were improved by 3.6% and 8.1%, respectively, when only one system was running. The proposed method can be widely applied to this type of air-cooled products.

Abstract:The factors that affect the freezing process in supercooler was analyzed based on the classical nucleation theory in this paper. Then, the experiment bench which is used to make ice slurry by supercooled method were set up to research the freezing process in the supercooler. The impact mechanism of flow and heat transfer process to freezing in supercooler was explored preliminarily combining with the theory of boundary layer. The experimental results show that the supercooled water nucleation process is influenced mutally by the heat transfer surface tempeature and the disturbance of fluid. The nucleation is mainly affected by heat transfer wall temperature when the Re number is small or the temperature of secondary refrigerant is low and is mainly affected by the fluid disturbance when the Re number is large.

Abstract:In this paper, conceptual model’s screening problems are solved via using DNA computing method. Firstly, it introduces skeleton structure to represent conceptual model, which is constructed in combination of head, deflection angle and skeleton curve. And then it proposes the deflection angle and skeleton curve DNA encoding method. Secondly, it designs the DNA computing algorithm process, whose feasibility is verified by the computer simulation. The DNA fragments are divided into 5 categories according to their length using K-means method. Thirdly, the evaluation parameter weights are determined by using information entropy calculating method and the evaluation function of conceptual model is established. Finally, the experimental results show that a reasonable evaluation function can basically describe the structural features of conceptual model and it could help designers find solutions effectively and efficiently. Furthermore, some common components can be extracted by comparing their scores due to the conceptual models, because similar scores of models have a high similarly and thus common components can provide raw materials for further design in the future.

Abstract:In order to improve the accuracy and efficiency of plant disease image segmentation, this paper propose a color image segmentation method based on level set and visual saliency. Firstly adopt a saliency detection algorithm based on wavelet transform to get the initial position of curve evolution in the active contour model, and construct an active contour model based on salient regions. Then design an edge detection operator of vector-valued image, and introduce it into the reconstruction of distance regularized level set evolution, to construct a new level set energy functional with a more flexible initial contour, faster evolution speed and more accurate object segmentation. Finally experimental comparisons demonstrate the proposed model has a good leaf disease segmentation effect.

Abstract:Considering the difficulty and problems in image matching for digital surface model (DSM) generation from high resolution satellite images (HRSIs) due to geometric projection and radial distortion, this paper has proposed an improved hierarchical image matching method based on triangle parallax constraints. In the method, scale invariant feature transform(SIFT) and normalized cross correlation (NCC) algorithms are used as well as epipolar geometric constraint and parallax constraint. Meanwhile, improvement is made for matching window adaptive optimization to generate DSM(digital surface model) from HRSIs based on matched feature points, grid points, and feature lines. Experiments were conducted to generate DSMs using HRSIs including WorldView-1 of Chongming island in Shanghai and ZY-3 of Zhoushan islands in Zhejiang province, and the effectiveness of the proposed approach was validated by control points and an existing DSM, with pixel level height accuracy achieved.

Abstract:To fit a plane with point clouds containing massive outliers, a fitting method with robust initial value by least trimmed squares (LTS) was presented. It firstly used LTS to ascertain initial plane coefficients by random sampling. Meanwhile, the median of all absolute deviations was adopted as initial mean square error of unit weight. Then it carried out selecting weight iteration. This method kept the high efficiency of selecting weight iteration as well as maintained the robustness of LTS. The test results show that selecting weight iteration with LTS initial value can keep robust to deal with point clouds including massive outliers. Finally, the accurate plane can be fitted.

Abstract:Based on the laser range equation for the extended Lambertian targets and the radiometric principles of laser scanners, the feasibility of original intensity image edge extraction is demonstrated, along with the eight neighborhood characteristics of non-edge points, edge points and noise points. By utilizing the eight neighborhood characteristics, a new dual-threshold criterion is proposed to distinguish and extract different points. According to the judgment results, the median filter algorithm is applied to filter the non-edge points and noise points, while for the edge points, their gray values keep unchanged. Finally, edge extraction is conducted by adopting the “Canny” algorithm. The proposed method is verified through actual experiment and the results of different dual-thresholds are discussed and analyzed. The results reveal that edge extraction can be effectively conducted on the raw intensity image, and the proposed approach can remove the salt and pepper noise of the intensity image as well as ensure the accuracy of edge extraction.

Abstract:A correction method for data model based on laser radar equation was presented for the laser intensity of point cloud from 3D laser scanning.The laser intensity value is corrected according to the different angles and distances, and the correction effect of the data model is also analyzed.With the corrected laser intensity value, the point cloud of building facades could be classified and the features could be extracted. The experiments results indicated that the correction model could effectively compensate laser intensity value, thus making the laser intensity value of congeneric objects trend to be unified.Therefore, the classification of point cloud and the feature extraction of building facades with corrected laser intensity value can guarantee the classification precision and target recognition effect.

Abstract:The edge residual-based a posteriori error estimates of conforming linear finite element method are studied for the monotone nonlinear elliptic problems. Under the assumption of u \in H1，we prove that the edge residuals dominate a posteriori error estimates, and obtain the computable global upper and local lower bounds on the error of the adaptive finite element method in H1 -norm. Up to higher order terms, edge residuals can be a posteriori error estimators. Numerical examples show the efficiency of the edge residual-based a posteriori error estimators.

Abstract:Define the $k$-th power $F_k$ of a graph $F$ as a graph on $V (F)$, in which two vertices are adjacent if their distance in $F$ is at most $k$. Given graphs $G$ and $H$, Ramsey number $R(G,H)$ is the smallest integer $N$ such that any red-blue edge-coloring of $K_N$ contains a red copy of $G$ or a blue copy of $H$. Recently, Pokrovskiy proved that $R(P_n,P_n^k)=(n-1)k \lfloor \frac{n}{k 1}\rfloor$, which solves a conjecture of Allen, Brightwell and Skokan. In this paper, we show that $R(P_n,C_n^k)=(n-1)(\chi(C_n^k)-1) \sigma(C_n^k) o(n)$ holds for fixed $k$ and $n\to \infty$.