Based on the distribution characteristic of magnetic field along the polish wheel, the four-axis linkage technique is advanced to replace a standard five-axis one to figure low-gradient optical surfaces with a raster tool-path in magnetorheological finishing (MRF). After introducing the fundaments of such simplification, the figuring reachability of a four-axis system for the low-gradient optics was theoretically analyzed. Further validation including magnetic field intensity and influence function characteristic was performed to establish its application. To demonstrate the correctness, feasibility and applicability of such technique, a K4 spherical part was figured by two iterations of MRF with surface form error improved to 0.219λ PV and 0.027λ RMS. Meanwhile, the surface roughness was also improved a lot in MRF process. These theoretical analyses and experimental results both indicate that high form accuracy and excellent surface quality can be obtained by using the four-axis linkage technique in the process of figuring low-gradient optical elements, and the four-axis linkage system undoubtedly is much more easy to control and much more economical.

A new experimental apparatus was set up to investigate the actual friction characteristics on the basis of speed control of the serve system. A modified friction model was proposed due to real time varying deformation resistance. The approach to identify the parameters of comprehensive friction behaviors based on the modified model was proposed and applied to the forging press. The impacts on parameters which the external load had were also investigated. The results show that friction force decreases with velocity in the low velocity regime whereas the friction force increases with the velocity in the high velocity regime under no external load. It is also shown that the Coulomb friction force, the maximum static friction force and the vicious friction coefficient change linearly with the external load taking the velocity at which the magnitude of the steady state friction force becomes minimum as the critical velocity.

A physically based analytical model was developed to predict the performance of the plateau observed in the gate C-V characteristics of strained-Si/SiGe pMOSFET. Experimental results were used to validate this model. The extracted parameters from our model were t_OX=20 nm, N_D=1×10¹⁶ cm⁻³, t_SSi=13.2 nm, consistent with the experimental values. The results show that the simulation results agree with experimental data well. It is found that the plateau can be strongly affected by doping concentration, strained-Si layer thickness and mass fraction of Ge in the SiGe layer. The model has been implemented in the software for strained silicon MOSFET parameter extraction, and has great value in the design of the strained-Si/SiGe devices.

An object segment similarity function is taken into account from the continuous media frames to measure the individual streaming profit of certain segment versions of a media object. Therefore, a new segment version-based transcoding (SVT) mechanism is derived for a quality of service (QoS) of client-centric media streaming in wireless mobile networks. The derived function utilizes the fuzzy similarity of certain segment versions of an object. This mechanism provides the effectiveness of reduction of the stream startup latency among segment versions, and the average access of each version. Thus, the proposed segment version transcoding mechanism reduces packet loss which in turn increases streaming performance and throughput. The performance of the partitioned segment versions is simulated and some segment versions are completed. The simulation results show that the proposed mechanism outperforms the other mechanisms in average cache hit ratio and in average startup latency ratio.

To deeply exploit the mechanisms of ant colony optimization (ACO) applied to develop routing in mobile ad hoc networks (MANETS), some existing representative ant colony routing protocols were analyzed and compared. The analysis results show that every routing protocol has its own characteristics and competitive environment. No routing protocol is better than others in all aspects. Therefore, based on no free lunch theory, ant routing protocols were decomposed into three key components: route discovery, route maintenance (including route refreshing and route failure handling) and data forwarding. Moreover, component based ant routing protocol (CBAR) was proposed. For purpose of analysis, it only maintained basic ant routing process, and it was simple and efficient with a low overhead. Subsequently, different mechanisms used in every component and their effect on performance were analyzed and tested by simulations. Finally, future research strategies and trends were also summarized.

r-learning, which is based on e-learning and u-learning, is defined as a learning support system that intelligent robots serve verbal and nonverbal interactions on ubiquitous computing environment. In order to guarantee the advantages of r-learning contents with no limits of time and place and with nonverbal interaction which are not in e-learning contents, in recent years, assessment criteria for r-learning contents are urgently required. Therefore, the reliable and valid assessment criteria were developed for nonverbal interaction contents in r-learning, and its detailed research content is as follows. First, assessment criteria for nonverbal interaction in r-learning contents will be specified into gesture, facial expression, semi-verbal message, distance, physical contact and time. Second, the validity of the developed assessment criteria will be proved by statistics. Consequently, the assessment criteria for nonverbal interaction contents will be helpful when choosing the better r-learning content and producing the better r-learning content, and the reliability of school education is improved ultimately.

Automatic image classification is the first step toward semantic understanding of an object in the computer vision area. The key challenge of problem for accurate object recognition is the ability to extract the robust features from various viewpoint images and rapidly calculate similarity between features in the image database or video stream. In order to solve these problems, an effective and rapid image classification method was presented for the object recognition based on the video learning technique. The optical-flow and RANSAC algorithm were used to acquire scene images from each video sequence. After the selection of scene images, the local maximum points on corner of object around local area were found using the Harris corner detection algorithm and the several attributes from local block around each feature point were calculated by using scale invariant feature transform (SIFT) for extracting local descriptor. Finally, the extracted local descriptor was learned to the three-dimensional pyramid match kernel. Experimental results show that our method can extract features in various multi-viewpoint images from query video and calculate a similarity between a query image and images in the database.

A new method for automatic salient object segmentation is presented. Salient object segmentation is an important research area in the field of object recognition, image retrieval, image editing, scene reconstruction, and 2D/3D conversion. In this work, salient object segmentation is performed using saliency map and color segmentation. Edge, color and intensity feature are extracted from mean shift segmentation (MSS) image, and saliency map is created using these features. First average saliency per segment image is calculated using the color information from MSS image and generated saliency map. Then, second average saliency per segment image is calculated by applying same procedure for the first image to the thresholding, labeling, and hole-filling applied image. Thresholding, labeling and hole-filling are applied to the mean image of the generated two images to get the final salient object segmentation. The effectiveness of proposed method is proved by showing 80%, 89% and 80% of precision, recall and F-measure values from the generated salient object segmentation image and ground truth image.

To make the dynamic assembly reliability analysis more effective for complex machinery of multi-object multi-discipline (MOMD), distributed collaborative extremum response surface method (DCERSM) was proposed based on extremum response surface method (ERSM). Firstly, the basic theories of the ERSM and DCERSM were investigated, and the strengths of DCERSM were proved theoretically. Secondly, the mathematical model of the DCERSM was established based upon extremum response surface function (ERSF). Finally, this model was applied to the reliability analysis of blade-tip radial running clearance (BTRRC) of an aeroengine high pressure turbine (HPT) to verify its advantages. The results show that the DCERSM can not only reshape the possibility of the reliability analysis for the complex turbo machinery, but also greatly improve the computational speed, save the computational time and improve the computational efficiency while keeping the accuracy. Thus, the DCERSM is verified to be feasible and effective in the dynamic assembly reliability (DAR) analysis of complex machinery. Moreover, this method offers an useful insight for designing and optimizing the dynamic reliability of complex machinery.

Respiratory monitoring is increasingly used in clinical and healthcare practices to diagnose chronic cardio-pulmonary functional diseases during various routine activities. Wearable medical devices have realized the possibilities of ubiquitous respiratory monitoring, however, relatively little attention is paid to accuracy and reliability. In previous study, a wearable respiration biofeedback system was designed. In this work, three kinds of signals were mixed to extract respiratory rate, i.e., respiration inductive plethysmography (RIP), 3D-acceleration and ECG. In-situ experiments with twelve subjects indicate that the method significantly improves the accuracy and reliability over a dynamic range of respiration rate. It is possible to derive respiration rate from three signals within mean absolute percentage error 4.37% of a reference gold standard. Similarly studies derive respiratory rate from single-lead ECG within mean absolute percentage error 17% of a reference gold standard.

An unmanned aerial vehicle (UAV) is arranged to explore an unknown environment and to map the features it finds when GPS is denied. It navigates using a statistical estimation technique known as simultaneous localization and mapping (SLAM) which allows for the simultaneous estimation of the location of the UAV as well as the location of the features it sees. Observability is a key aspect of the state estimation problem of SLAM. However, the dimension and variables of SLAM system might be changed with new features. To solve this issue, a unified approach of observability analysis for SLAM system is provided, through reorganizing the system model. The dimension and variables of SLAM system keep steady, then the PWCS theory can be used to analyze the local or total observability, and under special maneuver, some system states, such as the yaw angle, become observable. Simulation results validate the proposed method.

Similarity measure design on non-overlapped data was carried out and compared with the case of overlapped data. Unconsistant feature of similarity on overlapped data to non-overlapped data was provided by example. By the artificial data illustration, it was proved that the conventional similarity measure was not proper to calculate the similarity measure of the non-overlapped case. To overcome the unbalance problem, similarity measure on non-overlapped data was obtained by considering neighbor information. Hence, different approaches to design similarity measure were proposed and proved by consideration of neighbor information. With the example of artificial data, similarity measure calculation was carried out. Similarity measure extension to intuitionistic fuzzy sets (IFSs) containing uncertainty named hesitance was also followed.

It is a complicated nonlinear controlling problem to conduct a two-dimensional trajectory correction of rockets. By establishing the aerodynamic correction force mathematical model of rockets on nose cone swinging, the linear control is realized by the dynamic inverse nonlinear controlling theory and the three-time-scale separation method. The control ability and the simulation results are also tested and verified. The results show that the output responses of system track the expected curve well and the error is controlled in a given margin. The maximum correction is about ±314 m in the lengthwise direction and ±1 212 m in the crosswise direction from the moment of 5 s to the drop-point time when the angle of fire is 55°. Thus, based on the dynamic inverse control of feedback linearization, the trajectory correction capability of nose cone swinging can satisfy the requirements of two-dimensional ballistic correction, and the validity and effectiveness of the method are proved.

The occurrence of liquid condensation in natural gas accounts for new challenges during the interoperability between transmission networks, where condensation would lead to higher pressure drops, lower line capacity and may cause safety problem. A successful case of hydrocarbon dew point (HCDP) analysis is demonstrated during the mixing of natural gases in the transmission pipeline. Methods used to predict the HCDP are combined with equations of state (EOS) and characterization of C₆₊ heavy components. Predictions are compared with measured HCDP with different concentrations of mixed gases at a wide range of pressure and temperature scopes. Software named “PipeGasAnalysis” is developed and helps to systematic analyze the condensation problem, which will provide the guidance for the design and operation of the network.

As valuable energy in iron- and steel-making process, by-product gas is widely used in heating and technical processes in steel plant. After being used according to the technical requirements, the surplus by-product gas is usually used for buffer boilers to produce steam. With the rapid development of energy conservation technology and energy consumption level, surplus gas in steel plant continues to get larger. Therefore, it is significant to organize surplus gas among buffer boilers. A dynamic programming model of that issue was established in this work, considering the ramp rate constraint of boilers and the influences of setting gasholders. Then a case study was done. It is shown that dynamic programming dispatch gets more steam generation and less specific gas consumption compared with current proportionate dispatch depending on nominal capacities of boilers. The ignored boiler ramp rate constraint was considered and its contribution to the result validity was pointed out. Finally, the significance of setting gasholders was studied.

Thermogravimetric study of rubber compositions (operating glove and catheter) in medical waste was carried out using the thermogravimetric analyser (TGA), at the heating rate of 20 °C/min in a stream of N₂. The results indicate that the decomposition process of operating glove appears an obvious mass loss stage at 250–485 °C, while catheter has two obvious stages at 240–510 °C and 655–800 °C, respectively; both samples present endothermic pyrolysis reaction; the decomposition of operating glove and the first mass loss stage of catheter are in agreement with natural rubber pyrolysis; the second mass loss stage of catheter corresponds to CaCO₃ decomposition. Based on the experimental results, a novel two-step four-reaction model was established to simulate the whole continuous processes, which could more satisfactorily describe and predict the pyrolysis processes of rubber compositions, being more mechanistic and conveniently serving for the engineering.

Lysozyme reaction was developed as a novel technique for minimizing the amount of excess sludge in the sequential batch reactor (SBR). In the present work, excess sludge taken from a SBR system was treated by lysozyme reaction and then returned to the reactor. The quality of the effluent water and characteristics of the activated sludge in the SBR were analyzed to determine the effectiveness of the reduction process. The results show that excess sludge production could be reduced to almost 100% in the first 30 d of operation and could be reduced to further by 40% in the succeeding 20 d or so. In these time periods, the average removal efficiencies of the chemical oxygen demand and total nitrogen are 87.38% and 52.78%, respectively, whereas the average total phosphorous in the effluent is nearly 17.18% greater than that of the effluent of the reference system. After 50 d of operation, the sludge floc size is in the range of 20 to 80 μm, which was smaller than the size prior to the start of the hydrolysis and the ratio of mixed liquor volatile suspended solids/mixed liquor suspended solids increases from 86% to 90%.

To establish a theoretical foundation for simultaneous removal of multi-heavy metals, the adsorption of Cu(II) and Pb(II) ions from their single and binary systems by Ca-alginate immobilized activated carbon and Saccharomyces cerevisiae (CAS) was investigated. The CAS beads were characterized by Scanning electron microscope (SEM) and Fourier transformed infrared spectroscopy (FTTR). The effect of initial pH, adsorbent dosage, contact time and initial metal ions concentration on the adsorption process was systematically investigated. The experimental maximum contents of Cu(II) and Pb(II) uptake capacity were determined as 64.90 and 166.31 mg/g, respectively. The pseudo-second-order rate equation and Langmuir isotherm model could explain respectively the kinetic and isotherm experimental data of Cu(II) and Pb(II) ions in single-component systems with much satisfaction. The experimental adsorption data of Cu(II) and Pb(II) ions in binary system were best described by the extended Freundlich isotherm and the extended Langmuir isotherm, respectively. The removal of Cu(II) ions was more significantly influenced by the presence of the coexistent Pb(II) species, while the Pb(II) removal was affected slightly by varying the initial concentration of Cu(II). The CAS was successfully regenerated using 1 mol/L HNO₃ solution.

The components of urban surface cover are diversified, and component temperature has greater physical significance and application values in the studies on urban thermal environment. Although the multi-angle retrieval algorithm of component temperature has been matured gradually, its application in the studies on urban thermal environment is restricted due to the difficulty in acquiring urban-scale multi-angle thermal infrared data. Therefore, based on the existing multi-source multi-band remote sensing data, access to appropriate urban-scale component temperature is an urgent issue to be solved in current studies on urban thermal infrared remote sensing. Then, a retrieval algorithm of urban component temperature by multi-source multi-band remote sensing data on the basis of MODIS and Landsat TM images was proposed with expectations achieved in this work, which was finally validated by the experiment on urban images of Changsha, China. The results show that: 1) Mean temperatures of impervious surface components and vegetation components are the maximum and minimum, respectively, which are in accordance with the distribution laws of actual surface temperature; 2) High-accuracy retrieval results are obtained in vegetation component temperature. Moreover, through a contrast between retrieval results and measured data, it is found that the retrieval temperature of impervious surface component has the maximum deviation from measured temperature and its deviation is greater than 1 °C, while the deviation in vegetation component temperature is relatively low at 0.5 °C.

The subsidence of the mining area was monitored by analyzing the phase of permanent scatters (PS) which maintained high coherence in magnitude of SAR images. A new method of spatial unwrapping was presented which used the subsidence rates calculated on corner reflector (CR) points as constraints for PS network to perform the spatial unwrapping using the parametric adjustment method. The algorithm achieved the integration of CR data and PSInSAR algorithm. The colliery dense distributed area around Baisha reservoir was chosen as the study area in the experiment. The time series of subsidence from February in 2007 to February in 2010 is successfully inversed by using the periodic function to simulate the linear and nonlinear components of the deformation. The simulation results show that the accuracy can be ± 2.1 mm with the leveling data being used as the external validation data.

The pile-soil system interaction computational model in liquefaction-induced lateral spreading ground was established by the finite difference numerical method. Considering an elastic-plastic subgrade reaction method, numerical methods involving finite difference approach of pile in liquefaction-induced lateral spreading ground were derived and implemented into a finite difference program. Based on the monotonic loading tests on saturated sand after liquefaction, the liquefaction lateral deformation of the site where group piles are located was predicted. The effects of lateral ground deformation after liquefaction on a group of pile foundations were studied using the finite difference program mentioned above, and the failure mechanism of group piles in liquefaction-induced lateral spreading ground was obtained. The applicability of the program was preliminarily verified. The results show that the bending moments at the interfaces between liquefied and non-liquefied soil layers are larger than those at the pile’s top when the pile’s top is embedded. The value of the additional static bending moment is larger than the peak dynamic bending moment during the earthquake, so in the pile foundation design, more than the superstructure’s dynamics should be considered and the effect of lateral ground deformation on pile foundations cannot be neglected.

Rainfall infiltration depth and mode can severely influence slope stability. With the sustained rainfall, the influenced region of slope gradually expands. By using the Green-Ampt model to the soil slope, infiltration regulation was discussed under sustained and small intensity rainfall. And the infiltration rate of unsaturated soil was proposed according to the saturated infiltration theory. Because of the changing of initial moisture content in depth of slope, the saturated or unsaturated infiltration rate and depth could also be changeable with the sustained rainfall infiltration. Based on the principle of strength reduction, the calculation model of slope safety factor was established under different initial moisture contents and infiltration modes. Then, the slope stability was quantitatively analyzed through software FLAC^3D. The calculation results of soil slope engineering show that there is a shorter period for slope stability under different initial moisture contents and unsaturated infiltration ways at the slope wetting front. The stability period of slope is 33.3% according to different initial moisture contents of wetting front less than that of the same initial moisture content of wetting front. And the slope is easier to fail under the unsaturated infiltration. The results agree well with the actual situation under sustained and small intensity rainfall.

The lithology of fracture zone which was developed at the dam foundation of a hydropower station is weak sandstone with poor integrity and pore cementation contact. Its creep properties have a significant impact on the deformation and stability of the dam. Based on the characteristics of loose organizational structure, high moisture content and poor mechanical properties, the triaxial compression tests and creep tests were carried out, respectively. The results show significant non-linear, low strength and no obvious strength peaks. Both axial and lateral strains are achieved more than 3% when the tests are failed. The weak sandstone has a significant creep property, but only transient and steady state appear under low stress. Increased stress causes creep intensified and lateral strain gradually exceeds axial strain. In the failure stage, it has characteristics of large axial plastic deformation, obvious volumetric ductility dilation and large steady creep rate. The accelerated creep appears shortly after transient loading under confining of pressures 1.0 MPa and 1.5 MPa. Therefore, an improved Burgers creep model considering the non-linear characteristics of weak sandstone is built based on hyperbolic equation and the creep parameters are identified. This model can well describe the creep properties of weak sandstone.

The extreme temperature differences in flat steel box girder of a cable-stayed bridge were studied. Firstly, by using the long-term measurement data collected by the structural health monitoring system installed on the Runyang Cable-stayed Bridge, the daily variations as well as seasonal ones of measured temperature differences in the box girder cross-section area were summarized. The probability distribution models of temperature differences were further established and the extreme temperature differences were estimated with a return period of 100 years. Finally, the temperature difference models in cross-section area were proposed for bridge thermal design. The results show that horizontal temperature differences in top plate and vertical temperature differences between top plate and bottom plate are considerable. All the positive and negative temperature differences can be described by the weighted sum of two Weibull distributions. The maximum positive and negative horizontal temperature differences in top plate are 10.30 °C and −13.80 °C, respectively. And the maximum positive and negative vertical temperature differences between top plate and bottom plate are 17.30 °C and −3.70 °C, respectively. For bridge thermal design, there are two vertical temperature difference models between top plate and bottom plate, and six horizontal temperature difference models in top plate.

The nonlinear analysis of pounding between bridge deck segments subjected to multi-support excitations and multi-dimensional earthquake motion was performed. A novel bottom rigid element (BRE) method of the current displacement input model for structural seismic analysis under the multi-support excitations was used to calculate structural dynamic response. In the analysis, pounding between adjacent deck segments was considered. The seismic response of a multi-span bridge subjected to the multi-support excitation, considering not only the traveling-wave effect and partial coherence effect, but also the seismic non-stationary characteristics of multi-support earthquake motion, was simulated using finite element method (FEM). Meanwhile, the seismic response of the bridge under uniform earthquake was also analyzed. Finally, comparative analysis was conducted and some calculation results were shown for pounding effect, under multi-dimensional and multi-support earthquake motion, when performing seismic response analysis of multi-span bridge. Compared with the case of uniform/multi-support/multi-support and multi-dimensional earthquake input, the maximum values of pounding force in the case of multi-support and multi-dimensional earthquake input increase by about 5–8 times; the absolute value of bottom moment and shear force of piers increase by about 50%–600% and 23.1%–900%, respectively. A conclusion can be given that it is very necessary to consider the pounding effect under multi-dimensional and multi-support earthquake motion while performing seismic response analysis of multi-span bridge.

In the traditional strength reduction method, the cohesion and the friction angle adopt the same reduction parameter, resulting in equivalent proportional reduction. This method does not consider the different effects of the cohesion and friction angle on the stability of the same slope and is defective to some extent. Regarding this defect, a strength reduction method based on double reduction parameters, which adopts different reduction parameters, is proposed. The core of the double-parameter reduction method is the matching reduction principle of the slope with different angles. This principle is represented by the ratio of the reduction parameter of the cohesion to that of the friction angle, described as η. With the increase in the slope angle, η increases; in particular, when the slope angle is 45°, η is 1.0. Through the matching reduction principle, different safety margin factors can be calculated for the cohesion and friction angle. In combination with these two safety margin factors, a formula for calculating the overall safety factor of the slope is proposed, reflecting the different contributions of the cohesion and friction angle to the slope stability. Finally, it is shown that the strength reduction method based on double reduction parameters acquires a larger safety factor than the classic limit equilibrium method, but the calculation results are very close to those obtained by the limit equilibrium method.

A single specimen test using the three point single edge notched beam configuration at low temperatures for obtaining hot mix asphalt (HMA) resistance curves is developed. Resistance curves are obtained for mixtures at six temperature levels of +5, 0, −5, −10, −15, and −20 °C and three binder contents of 4%, 4.5%, and 5%. Crack extension increments during the test are measured by means of an image processing technique using Radon transform and feature extraction. All the specimens exhibit a rising R-curve, indicating ductility and toughening mechanisms in the ductile-quasi brittle fracture of the mixture. It is observed that the reduction of temperature results in a further tendency of the mixture for unstable crack growth and less subcritical crack length. It is also shown that using the binarization process, an automatic index can be developed that can represent the extent of brittleness and extent of the low temperature in which the cracking has occurred.

Based on Hamilton principle, the governing differential equations and the corresponding boundary conditions of steel-concrete composite box girder with consideration of the shear lag effect meeting self equilibrated stress, shear deformation, slip, as well as rotational inertia were induced. Therefore, natural frequency equations were obtained for the boundary types, such as simple support, cantilever, continuous girder and fixed support at two ends. The ANSYS finite element solutions were compared with the analytical solutions by calculation examples and the validity of the proposed approach was verified, which also shows the correctness of longitudinal warping displacement functions. Some meaningful conclusions for engineering design were obtained. The decrease extent of each order natural frequency of the steel-concrete composite box-girder is great under action of the shear lag effect. The shear-lag effect of steel-concrete composite box girder increases when frequency order rises, and increases while span-width ratio decreases. The proposed approach provides theoretical basis for further research of free vibration characteristics of steel-concrete composite box-girder.

The joint of clay core-wall and concrete cut-off wall is one of the weakest parts in high earth and rockfill dams. A kind of highly plastic clay is always fixed on the joint to fit the large shear deformation between clay core-wall and concrete cut-off wall, so the hydro-mechanical coupling mechanisms on the joint under high stress, high hydraulic gradient, and large shear deformation are of great importance for the evaluation of dam safety. The hydro-mechanical coupling characteristics of the joint of the highly plastic clay and the concrete cut-off wall in a high earth and rockfill dam in China were studied by using a newly designed soil-structure contact erosion apparatus. The experimental results indicate that: 1) Shear failure on the joint is due to the hydro-mechanical coupling effect of stress and seepage failure. The seepage failure will induce the final shear failure when the ratio of deviatoric stress to confining pressure is within 1.0–1.2; 2) A negative exponential permeability empirical model for the joint denoted by a newly defined principal stress function, which considers the coupling effect of confining pressure and axial pressure on the permeability, is established based on hydro-mechanical coupling experiments. 3) The variation of the settlement before and after seepage failure is very different. The settlement before seepage failure changes very slowly, while it increases significantly after the seepage failure. 4) The stress-strain relationship is of a strain softening type. 5) Flow along the joint still follows Darcian flow rule. The results will provide an important theoretical basis for the further evaluation on the safety of the high earth and rockfill dam.

The elasto-plastic damage model for concrete under static loading, previously proposed, was extended to account for the concrete strain-rate through viscous regularization of the evolution of the damage variables. In order to describe the energy dissipation by the motion of the structure under dynamic loading, a damping model which only includes stiffness damp stress was proposed and incorporated into the proposed rate dependent model to consider the energy dissipation at the material scale. The proposed model was developed in ABAQUS via UMAT and was verified by the simulations of concrete specimens under both tension and compression uniaxial loading at different strain rates. The nonlinear analysis of Koyna concrete dam under earthquake motions indicates that adding stiffness damp into the constitutive model can significantly enhance the calculation efficiency of the dynamic implicit analysis for greatly improving the numerical stability of the model. Considering strain rate effect in the model can affect the displacement reflection of this structure for slightly enhancing the displacement of the top, and can improve the calculation efficiency for greatly reducing the cost time.

In order to evaluate the seismic stability of reinforced soil walls against bearing capacity failure, the seismic safety factor of reinforced soil walls was determined by using pseudo-dynamic method, and calculated by considering different parameters, such as horizontal and vertical seismic acceleration coefficients, ratio of reinforcement length to wall height, back fill friction angle, foundation soil friction angle, soil-reinforcement interface friction angle and surcharge. The parametric study shows that the seismic safety factor increases by 24-fold when the foundation soil friction angle varies from 25° to 45°, and increases by 2-fold when the soil-reinforcement interface friction angle varies from 0 to 30°. That is to say, the bigger values the foundation soil and/or soil-reinforcement interface friction angles have, the safer the reinforced soil walls become in the seismic design. The results were also compared with those obtained from pseudo-static method. It is found that there is a higher value of the safety factor by the present work.

The objective of this work is to develop a novel methodology for determining real resistivity of conductive asphalt concrete based on two-electrode method. Due to an influence of contact resistance, the measured resistivity is always not equal to the real resistivity. To determine the real resistivity, a linear relationship of the measured resistivity, contact resistance and the real resistivity was established. Then experiments for six specimens with varying graphite contents were designed and performed to validate the formulation. Results of experiments demonstrate that the slope of the line represents contact resistance, and the intercept indicates the real resistivity. The effects of graphite content on contact resistance and real resistivity are also revealed. Finally, results show that the influence of contact resistance on accuracy of resisitvity measurement becomes more serious if graphite content is beyond 3%. Hence, it is the time to choose this novel methodology to determine the real resistivity of asphalt concrete by taking account of contact resistance.

With the digital image technology, a crack detection method of reinforced concrete bridge was studied for the performance assessment. The effects including the image gray level, pixel rate, noise filter, and edge detection were analyzed considering cracks qualities. A computer program was developed by visual C++6.0 programming language to detect the cracks, which was tested by 15 cases of bridge video images. The results indicate that the relative error is within 6% for cracks larger than 0.3 mm cracks and it is less than 10% for crack width between 0.2 mm and 0.3 mm. In addition, for the crack below 0.1 mm, the relative error is more than 30% because the bridge is in safe stage and it is very difficult to detect the actual width of crack.

In many Chinese cities, motorized vehicles (M-vehicles) move slowly at intersections due to the interference of a large number of non-motorized vehicles (NM-vehicles). The slow movement makes a part of M-vehicles fail to leave intersections timely after the traffic signal turns red, and thereby conflicts between vehicles from two directions occur. The phenomenon was analyzed graphically by using the cumulative vehicle curve. Delays in three cases were modeled and compared: NM-vehicle priorities and M-vehicle priorities with all-red intervals unable to release all vehicles, and longer all-red intervals ensuring release all vehicles. Marginal delays caused by two illegal behaviors that occasionally happened in mixed traffic intersections were also investigated. It is concluded that increasing the speed of M-vehicles leaving intersections and postponing the entering of NM-vehicles are the keys in mathematics, although they are uneasy in disordered mixed traffic intersections due to a dilemma between efficiency and orders in reality. The results could provide implications for the traffic management in the cities maintaining a large number of M- and NM-vehicles.

Aimed at the uncertain characteristics of discrete logistics network design, an interval hierarchical triangular uncertain OD demand model based on interval demand and network flow is presented. Under consideration of the system profit, the uncertain demand of logistics network is measured by interval variables and interval parameters, and an interval planning model of discrete logistics network is established. The risk coefficient and maximum constrained deviation are defined to realize the certain transformation of the model. By integrating interval algorithm and genetic algorithm, an interval hierarchical optimal genetic algorithm is proposed to solve the model. It is shown by a tested example that in the same scenario condition an interval solution [3 275.3, 3 603.7] can be obtained by the model and algorithm which is obviously better than the single precise optimal solution by stochastic or fuzzy algorithm, so it can be reflected that the model and algorithm have more stronger operability and the solution result has superiority to scenario decision.