Abstract:Subjected to complex internal and external environment, the degradation of concrete lining in urban metro tunnels seems inevitable. It is difficult to repair it by traditional methods. Concretes with microencapsulated healing agents are very appealing due to the advantage of self healing and potentiality of controllable healing on a large scale with little initial damage. Based on Taylor’s model, a 2D self healing micromechanical model of microcapsule enabled self healing concrete in underground structures subjected to tensile load is proposed. The kinetic equations of damage healing evolution and the formulations of compliance after healing are developed. In the end, the comparison between the theoretical and experimental results of microcapsule enabled self healing mortars verifies that with the model, the phenomenon of damage and healing of microcapsule enabled self healing concrete in underground structures can be simulated, and rational results can be obtained.

Abstract:The numerical manifold method (NMM) provides a uniform framework for analyzing both continuum and discontinuum. Incorporating the advantages of the NMM formulations and the well known Goodman element, a novel method for modeling the rock discontinuities is developed. The method which is particularly suitable for modelling joint or weak layer in rock, is proved to greatly simplify the preprocessing and analysis of the jointed rock mass, as a result, it is generally applicable for rock mechanics and rock engineering. Several test examples illustrate the correctness and effectiveness of the proposed method.

Abstract:Based on the similarity principle and the conservation of mass, the microscopic fraction disintegration and macro distribution of rock particles are discussed separately, and the correlation fractal dimension calculation formula about rock disintegration is also presented. On this basis, the fractal evolution law of clay rock disintegration under different pH conditions is investigated. The results show that, the smaller the pH value, the greater the fractal dimensions in the preliminary stage and the fewer the cycle times to obtain the stable fractal dimension. In addition, the acid solution accelerates the growth of particle fractal dimension, but the alkaline solution plays a role of reverse. It needs more cycle times that the fractal dimension curves become stable in the alkaline conditions. However, the fractal dimension under different pH conditions should tend to be equal ultimately.

Abstract:Because of harsh environment on the lunar surface，the conventional terrestrial excavation equipments on the earth can’t perform perfectly on the moon. On the contrary, the utilization of high pressure gas which will expand sharply on the condition of vacuum eliminate the mechanical friction of terrestrial equipment and use the hard vacuum environment intelligently at the same time. The frequency of high pressure gas injection, burial depth of excavation tube and pressure of high pressure gas will make a difference in the mass efficiency（the quality of lunar regolith simulant excavated by 1 g gas），in order to analyze the affection of these three factors to mass efficiency，we invent a test device which work under the vacuum circumstance based on the utilization of high pressure gas. Results of orthogonal test on the factors affecting the efficiency show that the maximum mass efficiency occurs when the frequency of high pressure gas injection was 0.5 s open and 0.5 s closed; the mass efficiency is in direct proportion to burial depth of excavation tube; a reasonable pressure value is in need for maximum quality efficiency.

Abstract:Condition assessment method for temporary structure is established based on system reliability analysis method. Failure models of temporary structures are established by the combined method with finite element analysis and series parallel model. Values of resistances, loads, and human errors of temporary structure in construction stage are discussed, and reasonable reliability models are proposed. Effects of wind loads and human errors on the temporary structure are considered, and component level and system level reliability assessment are analyzed respectively. Finally, performance of a triangle traveler is analyzed with the system reliability method. Results show that, using system reliability analysis method for temporary assessment can not only solve the uncertainties of resistance and load well, but also ensure the whole structure to have the same reliability.

Abstract:Fatigue performance of orthotropic steel decks with U rib was investigated based on the specific constructional detailing of the steel railway decks. Two full scale specimens, DECK1 which had the inner diaphragms in the U ribs, and DECK2 which did not have the inner diaphragms were tested under the static loading and the high cycled loading. Test results show that inner diaphragms in the U ribs help to redistribute stress in web of the rib and stress in diaphragm of the crossbeam, and hence to improve the fatigue strength of rib to diaphragm detail in the orthotropic steel railway decks. Fatigue cracks initiates very likely from the toe of the rib to diaphragm welds, and both specimens develop horizontal cracks in the web of rib at the position close to the rib to diaphragm connections. Finite element (FE) model of the decks is developed and the results agree well with the test results. Influences of the inner diaphragms in the U ribs on the stress state and the fatigue performance of the deck were analyzed.

Abstract:Through model tests, an analysis was made of the stress characteristics of partially grouted anchors in soil slope under surface load with a focus on the stress characteristics of each row anchor and its changes with the load time under the loads, the stress histories of anchor with surface load’s increase, as well as time of anchors’ maximum and stable stress states under different loads. Comparison was done about stress differences between partially grouted anchor and fully grouted anchor. Results show that the strain of top partially grouted is the largest and that of bottom anchors is the lowest under ground loads; the strain of top and middle partially grouted anchors is larger than the bottom anchors’ under lower loads, but the strain of bottom fully grouted anchor is the largest and that of top fully grouted anchor is the lowest; under larger loads, the strain of top grouted anchors are the largest and that of bottom anchors is the lowest, which is similar to the fully grouted anchors; under the same load, the strain of partially grouted anchor increases under a sustained load, and then decreases; with the increase of loads, the peak strain increases to the maximum at first, and then decreases gradually, but increases at last. So, when a structure of anchors is designed to support a man made soil slope, all level loads should be considered in order to make the slope safe.

Abstract:A series of model tests on static and cyclic axial response of the single pile in sandy soils are described. The accumulated settlement and cyclic amplitude of settlement of piles are investigated for different scour depths. The results indicate that the increase of scour depth can induce the increase of accumulated settlement of piles under cyclic loading. For smaller scour depths, the accumulated settlement and average rate of settlement tend to stable at less cycles. However, for larger scour depths, the accumulated settlement is large and develops very fast and needs longer time to reach stable, which even causes the sustainable development of accumulated settlement to lead to failure of piles. The effect of long term accumulated settlement on bearing capacity should be considered in engineering practices.

Abstract:The sediment deposition problem of Huanghua Port is a key factor to influence the navigation capacity and investment in construction. After the regulation project in 2011, the navigation capacity of Huanghua Port was greatly improved, the sediment siltation was mitigated, and a steady water area was, therefore, provided for harbour basin. On the basis of the verified tidal current and sediment transport mathematical model from MIKE 21 software, the responses of the tidal current field and sediment concentration field to the engineering area of Huanghua Port in 2011 were analyzed. Besides, the changes of sediment concentration in the whole field whether the normal wave being considered or not were compared. The results indicate that the extension of breakwater divides Huanghua Port into two relatively separate regions, and the resistance induced by breakwaters forces the sediment carried by tidal current to transport along the dike seaward; the average sediment concentration in Huanghua Port is about 0.02 kg·m-3 without the effect of wave, however, the sediment concentration increases drastically and forms high sediment concentration zone in offshore water when considering the effect of normal wave; Breakwaters, which can block high concentration of sediment across the channel, improve the service life of the navigation channel.

Abstract:For researching the discipline of passenger flow in urban public transportation corridor, this paper focuses on the problem about passenger departure time and mode choice behavior along this corridor. A dynamic passenger flow analysis model is presented, which is composed of two parts. First, dynamic passenger flow equilibrium assignment sub model, which refers to departure time and path/mode choice of passenger, is established. Then, the paper proposes passenger travel disutility sub model. And a heuristic solution algorithm is developed to solve these two sub models. The paper chooses a real numerical example to illustrate the application of the dynamic passenger flow analysis model and solution algorithm. Based on the analysis result, this model can simulate the time space distribution of passenger flow in urban public transportation corridor with a consideration of some factors which influence travel disutility on the departure time and mode choice behavior of passenger, such as travel time, in vehicle crowding and so on. Obviously, this dynamic passenger flow analysis model can provide important support for improving the service level and efficiency of urban public transportation corridors.

Abstract:Two echelon vehicle routing problem(2E VRP) is a novel kind of vehicle routing problem in which freight from depot to customers is compulsorily delivered through intermediate depots (named satellites). The first echelon is from depot to satellites, while the second from satellites to customers. This paper proposes a multi start variable neighborhood descent algorithm to solve 2E VRP according to the characteristics of this problem. First, an improved Split algorithm continuously splits random permutations of all customers until a feasible second echelon distribution scheme appears. Then, a complete initial feasible solution is obtained by solving the first echelon problem and then further improved by a variable neighborhood descent (VND). When no improvements can be found by VND, the preceding process is repeated by multi start skills until the algorithm is terminated. Computational results show that the proposed algorithm is easy to implement and it outperforms the best two existing heuristics for 2E VRP.

Abstract:In order to deal with the confliction between the safety of the pedestrian crossing and the efficiency of the vehicle traffic on urban arterial, this paper proposes a method for signal designing of mid block pedestrian crossing, which provides an appropriative signal phase for the pedestrian by using the red time of the vehicle at downstream intersection. The method is formulated as a mixed integer linear programming. The control objective is to maximize the duration of green for pedestrian on the basis of ensuring the safety of the pedestrian crossing and maintaining the efficiency of the vehicle traffic in status quo. The effect and the maneuverability of the control method are tested by VISSIM simulation and case study. Results show that in the case of successive crossings, the pedestrian crossing can be located at anywhere of the road section and the suitable signal timing can always be made. And in the case of non stop crossing, the designing of the location of pedestrian crossing and signal control should be considered synchronously.

Abstract:The fatigue performance of terminal blend rubberized asphalt mixture was researched by BFA which was selected to do four point bending beam fatigue tests. The fatigue performance considering self healing between Terminal Blend AC13 and SBS AC13 was compared which had the same air voids. Further research was done on fatigue performance and high temperature performance of the compound modified asphalt mixture though mixing SBS into terminal blend rubberized asphalt. The results show that NfNM is more suitable than Nf50 to be the fatigue damage standard for terminal blend asphalt mixtures. The correlation of terminal blend asphalt mixture’s fatigue performance and three factors which are strain, asphalt content and air void ratio is researched. Terminal blend asphalt mixture AC13’s fatigue equations is regressed. Regardless of whether the self healing is considered, when the air voids of mixture is 4%, SBS AC13 has longer fatigue life than TB AC13, but TB AC13 gets better self healing capability. Regardless of whether the self healing is considered, when the air voids of mixture is 4%, the fatigue life of TB+SBS AC13 is twice as much as the fatigue life of SBS AC13, and also TB+SBS AC13 gets better self healing capability than SBS AC13. The high temperature performance of TB+SBS AC13 can far exceed the SBS AC13.

Abstract:Pavement strain and deflection of Denver International Airport runway are analyzed to study dynamic response of the airport runway when Boeing777 taxiing on it. The results show that the closer the wheel loads from the sensor, the greater the strain and deflection. There are three peak points for the deflection curve of location near the transverse joint, corresponding to the aircraft’s three axles, while deflection curves for location near central slab and mid longitudinal joint are semi sinusoidal shaped, with only one peak point. When loading at transverse joint edge, void occurs between slab and base for neighboring slab without loading. Settlement of foundation takes up the main part of total settlement amount of pavement, inelastic deformation occurring in depth of 3.05~6.10 m range is very small, which implies that the ground below 3.05 m depth can be regarded as elastic foundation. Transverse strain of slab shows three times fluctuating after reaching a certain level, while longitudinal strain displays twice transforming between tension and compression, and strain recovery between wheel loads at longitudinal joint edge is significant, which means more prone to fatigue damage. Offset of neutral plane due to bonding effect is greater at central slab than at the edge, so the interface between slab and base at the edge can be considered as separated, while bound state is employed at the center. These conclusions are useful as guidance for the optimum design and scientific construction of airport runways.

Abstract:In order to study the vibration effect generated by rail vehicles transiting on the adjacent buildings of Hu Hang railway passenger dedicated line in Xinzhuang Station pivotal project, Xinzhuang Station half space integration finite element model was established. According to loading analysis model for the train vibration and mathematical expression, wheel rail force was calculated through field test rail acceleration data of Hu Hang railway passenger dedicated line. Simulating and analysis vibration level of Hu Hang railway passenger dedicated line adjacent buildings, under ballast track and with additional isolation base working condition. The result shows that in the case of ballast track, vibration influence on T17 adjacent serviced apartment, at a distance of 10m from track, generated during Hu Hang railway passenger dedicated line operation is significant, and the VLzmaxis 79.68 dB; vibration influence on T17 adjacent residential building, at a distance of 97 m from track, is small, and the VLzmaxis 59.1 dB. Under the condition of addition isolation base structure, the VLzmax of T17 adjacent serviced apartment is 62.96 dB, reducing 16 dB relating to ballast track condition, and the vibration isolation effect is significant. By applying additional isolation base structures, the VLzmax values of different floors in the two building decreased effectively, national and local standards were satisfied.

Abstract:The Peck empirical equation is the most common method in the calculation of upper railway settlement at shield tunnel cross section. However, due to the shield tunnel oblique crossing upper railway, shield tunnel cross section is no more parallel to the upper railway direction and the settlement cannot be expressed as Gaussian distribution. The shield angle coefficients are proposed to modify the Peck equation with consideration of oblique angle, tunnel gradient and upheaval. The modified Peck equation is verified by finite element numerical analysis, which is applicable for settlement expression in different sections. And with the different settlement and composite irregularity being obtained by the modified Peck method, the rail surface irregularity is affected. With dynamic simulated analysis, the influence on derail coefficient and wheel load reduction rate is researched.

Abstract:In order to eliminate the interference between steering linkage and suspension guiding mechanism and to achieve accurate independent steering motion as well as to improve system integrated level and use the same independent suspension / in wheel motor module on both front and rear wheels of four wheels steering electric vehicles without axle shafts, an integrated system of the independent steer by wire system and the suspension guiding mechanism is presented. The formulas for the kinematic analysis of the suspension are derived based on the theory of spatial mechanism, and a sensitivity analysis of the single variables to the suspension kinematic parameters is done by using MATLAB. The virtual prototype model of the suspension guiding mechanism is established by using ADAMS/Car. The optimization variables are selected out according to the analysis results on MATLAB. A sensitivity analysis of the suspension guiding mechanism is made in the ADAMS/Insight, then the critical optimization design variables are found out. The suspension guiding mechanism is optimized according to the analysis results above. The kinematic performance of the suspension is improved.

Abstract:In order to improve the ride comfort and stability of one light bus with two level variable stiffness rear suspension, a virtual combined optimal model was composed of the multi objective immune system algorithm（MISA) program composition by MATLAB and a virtual dynamic optimal model of the light bus in Adams Car. The parameters of the front and rear suspension were reasonably optimized. To ensure the accuracy of the model, the tire mechanical characteristics were tested, then the Magic Formula tire model was obtained by parameter identification method. An optimal method for the light bus’s suspension systems was put forward. In the proposed method, the torsion stiffness of front torsion bar, the front and rear damping curve coefficients, the torsional stiffness of front and rear stabilizer bars and the two level stiffness of rear suspension were taken as the optimal antibodies(variables). The max lateral acceleration of steady static circular simulation, the yaw rate and roll angle of the body of slalom simulation, and the Z direction acceleration root mean square(RMS) of the frame on B class road(80 km·h-1) were selected as the optimal antigen target. By using MISA to conduct optimization, the optimized suspension parameters were obtained. Finally, the suspension samples were manufactured and the comparative trials of vehicle ride comfort, handling and stability and subjective evaluation test were respectively carried out in an automotive proving ground to evaluate the optimization results. The results show that the proposed optimization method can be used for improving the vehicle’s ride comfort and stability and it has become a development trend of automotive computer aided optimization(CAO) technology. Therefore, it will provide guiding significance for the virtual development and optimization of automotive chassis.

Abstract:The rigid ring coupling model of electric wheel with the consideration of the flexible connection between rim and drive motor was established to analyze the vibration responses of the electric wheel with the high frequency torque input. And the main stiffness parameters were identified through the operating modal analysis of the electric wheel. With the calculated tread parameters, the inherent characteristic of the established tire model was analyzed. The electric wheel model had the ability to represent the first order modal of both the radial and rotational directions exactly. And the flexible connection between the rim and motor changed the inherent frequencies of the tire ring and the rim. The torque excitation of the frequencies acquired from the drum test was brought to the electric wheel model. The responses show that the flexible connection between the rim and the motor could decrease the vibration response of the tire and car body at the frequencies nearby the first order radial frequency. This research offers the theoretical guide for the structural design of the electric wheel.

Abstract:A transient dynamic finite element model of disc pin system was established with finite element analysis(FEA) software ABAQUS. The transient dynamics FEA model successfully predicted the disc and pin motion state, the frictional contact state and feed in energy of the system as well as nonlinear frequency coupling phenomenon of the disc pin frictional self excited vibration system. Results showed that, there existed simultaneously warp caused by mechanical action and high frequency normal vibration on disc. Vibration mode of the pin rod was bent based, supplemented by torsional vibration, and had pure sliding limit cycle. The contact pressure distribution had periodic variation characteristic, and the normal and friction force influenced the frequency. There existed simultaneously feed in and feed out energy in the system, and the feed in energy which was dominant in the system caused friction squeal.

Abstract:Robot technology is widely applicated in fields such as industral manufacture, medical service, exploration and exploitation, bio engineering, rescue, etc. Traditional robots have rigid underlying structures that limit their ability to interact with their environment. Soft robots are the novel bionic continuum robots, which can change their own size and shape in large range and have great potentials in the unstructured enviroment. This paper presents a review about the bionic mechaism, driving mode, modeling and control strategy for soft bodied robots. Some bottlenecks constraints and feasible solutions of soft robot technology are also summarized by means of analysis and classification. Finally, the trends in robot technology are investigated.

Abstract:Cabled seafloor observatory networks (CSONs) can provide a large amount of undersea scientific instruments with sustained and abundant power. According to the principles of reliability and economy, the paper illustrates why the power system of CSONs is suitable to adopt the negative monopole DC transmission scheme with the seawater as the current returning path by parallel connecting undersea loads, and employing the cascaded high frequency DC DC conversion system, and then the CSONs’ physical structure is established based on the analysis. According to the CSON’s characteristics, several typical undersea power system topologies are summarized. With the average power feeding reliability of the undersea stations as the reliability index, the reliability indexes of these typical topologies are calculated and compared. This method can provide a basis for the CSONs’ topology planning. Furthermore, the operation mode of the undersea power system is designed to enhance the CSONs’ fault tolerance capability. The study can be a reference for the future construction of large scale national CSONs.

Abstract:An insulator contamination grades measurement method based on feature level fusion of visible image information in red green blue (RGB) and hue saturation intensity (HSI) color spaces is proposed. Optimal entropic threshold (OET) segmentation algorithm is adopted to segment insulator surface. Features of RGB and HSI color spaces are calculated separately. Meanwhile, feature selection based on Fisher criterion is applied to obtain features which have the ability to represent the contamination grades efficiently. Kernel principal component analysis (KPCA) is adopted to carry out dimensionality reduction fusion of the combination of features and obtain three dimensional fused features. Probabilistic neural network (PNN) is used to identify the contamination grades. The experimental results indicate that the feature level fusion of image information based on KPCA has capability to characterize the contamination grades comprehensively. Compared with recognition using RGB or HSI features solely, the proposed method can obtain higher recognition accuracy and realize the contamination grades recognition effectively. A new method for the prevention of pollution flashover is presented.

Abstract:According to the reciprocal preference theory, the knowledge sharing incentive model of project team with two agents was established by introducing the conflicts of the effort of work and knowledge sharing. Thus an analysis was made of the influence of reciprocal preference on effort of knowledge sharing, effort of working, team expected utility and the incentive level of knowledge sharing, and then the related digital simulation was presented to prove the model theoretical analysis conclusions. The results show that when considering the influence of the work conflict, the role of reciprocal preference on effort of working, knowledge sharing incentive, team expected utility and soon are not absolutely active. However, it may improve the effort level of knowledge sharing.

Abstract:Represented by owner contractor conflict, project conflict influences cost performance diversely in different project delivery systems, due to their differences in source of conflict, project attributes, and the internal/external environment of organization. Based on the interactionist view of conflict, this paper tested the relationship between the owner contractor conflict and cost performance in design bid build (DBB) and design build (DB) projects with 187 valid questionnaires. Hypotheses were tested by using correlation analysis and regression analysis. Results indicate that the owner contractor conflict in DBB projects influences the project cost performance with an inversed U shape, which means a moderate level of conflict can improve cost performance until a certain point beyond which the cost performance diminishes. However, the owner contractor conflict in DB projects mainly produces negative impact on the project cost performance rather than the functional outcomes.