In order to reveal the influence of anisotropic stiffness on tire mechanical properties and vehicle handling characteristics under combined slip situations. Firstly, the direction factor is introduced to describe the direction of resultant shear force in the contact patch, which improves the modeling accuracy of UniTire for combined slip tire forces; Secondly, the influence of anisotropy degree on tire mechanical properties is analyzed based on test data, and the expression of effective cornering stiffness considering the influence of tire anisotropy is constructed; Then a vehicle handling analysis model considering the influence of tire anisotropy is established, and the influence of longitudinal acceleration on vehicle handling characteristics is analyzed with different anisotropy values; Finally, the analysis results are simulated and validated with CarSim. The results show that with the strong anisotropy value, different braking/driving torque distribution modes have little effect on vehicle handling characteristics under combined slip situations. However, with the weak anisotropy value, the vehicle handling characteristics under combined slip situations are significantly affected by different braking/driving torque distribution modes.

A winglet can use the three-dimensional flow, generated by the wingtip, to provide the wing with additional lift and forward thrust. Its unique mechanism of action is also suitable for the application to a car empennage. However, because the wake of a vehicle has many differences with an aircraft, traditional airfoils of an aircraft are difficult to satisfy the design requirements of a winglet that is installed on the car empennage. Meanwhile, adding a winglet will create new aerodynamic load distribution due to the additional elastic deformation. Therefore, the design and optimization of a car-use winglet is needed. Firstly, quasi-uniform B-spline curve was applied to fit the airfoil, then the fitting airfoil was employed in building the three-dimensional model of the winglet. After that, the Bi-directional fluid-structure interaction was used to add the actual influence of static aeroelasticity on the car empennage with the winglet. Finally, the airfoil shape and shape parameters of the winglet were optimized with the three-dimensional numerical simulations. Wind tunnel tests were performed to validate and compare the results of numerical optimization, showing that the numerical simulations have high fidelity. The results of wind tunnel tests and numerical simulations indicate that, through design and optimization, a winglet can reduce drag and produce additional downforce for a vehicle with an ordinary car empennage. Compared with a rigid winglet, the optimal solution set of the new car empennage, under the influence of static aeroelasticity, have the trend to increase the lift coefficient and reduce the drag coefficient of the car model.

Diesel engines have been widely applied in the fields of transportation and manufacturing due to their advantages such as good power, economy and reliability, but the subsequent pollutant emissions are increasingly serious. Among them, the particular emissions seriously pollute the environment and endanger human health. As emission regulations are becoming gradually stricter, the after-treatment technology to control particulate emission has been a hot spot for research. Diesel Particulate Filter (DPF) has been proved to be the most effective after-treatment equipment to control diesel particulate emission, but the regeneration method and strategy of DPF are the key technical questions. DPF regeneration technology generally includes active regeneration and passive regeneration. Active regeneration has become the mainstream of DPF regeneration method due to its completeness and safety. The precise control of DPF regeneration temperature is the key to its thoroughness and safety. In order to study the influence of exhaust thermal management measures on the heating characteristics of Diesel Oxidation Catalyst (DOC) and other engine performances during DPF regeneration of diesel engine, two typical working condition modes at low speed and medium-light load (working condition 1 was 1 250 r/min and 25% load, working condition 2 was 1 250 r/min and 40% load), which had low exhaust temperature, were selected to research. The test results show that increasing late post injection quantity has little effect on the exhaust temperature at the entrance of DOC. The heating rate inside DOC is increased and the time of peak heating rate is shortened, and the heavier the load the more obvious the effect. The conversion efficiency of hydrocarbon (HC) is improved but HC emissions deterioration is obvious, Brake Specific Fuel Consumption (BSFC) and oil dilution are worsened. Therefore, the late post injection quantity should be controlled reasonably. When the intake throttle opening is reduced, the air intake mass flow is decreased, the exhaust temperature at DOC inlet is increased, the heating response is slowed but the peak of heating rate is higher. The peak temperature appeares at middle and posterior of DOC during heating process. The experimental results and conclusion lay experimental foundation for DPF active regeneration method and strategy.

In this study, carbon fiber and glass fiber reinforced materials and epoxy resin matrix materials were used to design the layer structure of automobile engine hood. Sample of automobile engine hood is manufactured and comparative analysis of its performance is conducted. The results show that the fiber reinforced engine hood can not only meet the requirements of stiffness and modal, but also effectively reduce the weight of the engine hood. Under different working conditions, the simulation results of the free modal, transverse bending stiffness and torsional stiffness of the engine hood were compared with the experimental results and the performance of the original steel engine hood, which verified the effectiveness of the design. The optimization design of the composite engine hood was further studied. Compared with the initial design, the weight of the engine hood was further reduced by 9.7% through optimization. The design gives full play to the advantages of the fiber composite material in automobile lightweight.

The aerodynamic noise in the front window area mainly originates from the exterior rearview mirrors. To reduce the aerodynamic noise in this area, numerical simulations of five rearview mirrors were carried out based on the rearview mirror-plate wind tunnel experiment. The realizable k-ε model was used for steady-state analysis, and the separation vortex simulation was based on the realizable k-ε model for transient analysis. The noise data monitored by this numerical simulation method was basically consistent with the wind tunnel experiment results. The plane streamline diagrams, surface acoustic power diagrams and pressure cloud diagrams of the 5 rear-view mirrors are analyzed and compared. The shape factors that affect the aerodynamic noise of the front window area, such as mirror cover, base shape and installation angle are summarize. Results suggest that adjusting and combining these modeling factors properly can effectively reduce the influence of the rearview mirror on the aerodynamic noise of the front side window, which provides a good reference for the optimal design of the rearview mirror.

This paper took a 50-type wheel loader as the research object. Considering the driving, working and structural characteristics of the wheel loader, a loader simulation model containing the loaded material information was established using RecurDyn and EDEM. Based on the driver's experience, the process of shoveling bulk materials was analyzed, and the shovel performance indexes reflecting the comprehensive performance of the bucket filling rate and fuel consumption were constructed. On the above basis, the shovel performance under different working conditions and different trajectory parameters was analyzed. The approximate response relationship between the shovel performance and the trajectory parameters under different working conditions was established using Kriging method. The theoretical trajectory parameters of the shovel under different working conditions were obtained by using Particle Swarm Optimization (PSO). The results show that the shovel performance is significantly improved with the optimized trajectory parameters.

To solve the problem that it is difficult for commander on the ground and driver to operate cranes cooperatively, an intelligent control method of the crane based on BiLSTM model was proposed, which realizes single-person control of crane, thus, reducing manpower cost. Firstly, Kinect sensors were used to collect the coordinates of human joints from the commander's instructions. Then, the vectors of human joints were constructed using the coordinates, and two kinds of characteristic matrices that distinguish different instructions were constructed by calculating the angles and modulus ratios between the vectors. After that, the feature matrix of angle was input into the instruction recognition network based on BiLSTM model, and the recognition results were compared with those of support vector machine (SVM) and back propagation (BP) neural networks. Finally, the feature matrices of angle and modulus ratio were fused to improve the accuracy. The experimental results show that the instruction recognition network designed in this paper achieves the highest accuracy rate and the proposed fusion recognition method utilizes the information of multiple features effectively. For the training set, the recognition rate can reach 99.13%, and for the test set, this rate can reach 96.75%.

In order to recharge pure electric Load-Haul-Dump (LHD), a pantograph-catenary continuous energy charging system is proposed. The pantograph-catenary continuous energy system parameters, such as pantograph-catenary structure, bow head trajectory, bow angle and balance bar angle, are designed according to the pantograph dynamic characteristics and working conditions between pantograph and roadway. Based on the established pantograph dynamics calculation model, combined with the multi-objective optimization algorithm, the 10t pure electric LHD pantograph is designed. Based on the nonlinear finite element theory, the finite element model of the pure pantograph-catenary system of LHD is established. The dynamic simulation and verification analysis of pantograph-catenary current were carried out through MARC software. The results show that the pantograph-catenary continuous system can complete the pure electric LHD continuous charge in only 12.5 s under the premise of ensuring the safe operation of the LHD, which improves the efficiency of LHD operation and can be widely generalized.

To drive the robotic manipulator tracking the desired trajectory, a novel modern control method based on the nonsingular terminal sliding mode is designed in this paper. Combining the traditional fast terminal sliding mode and the nonsingular terminal sliding mode, the proposed control method possesses the characteristics of rapidity, nonsingularity, finite-time convergence and strong robustness. The chattering from sliding mode controller can also be suppressed effectively. Here, the mathematical model of robotic manipulator structure which can be simplified as a 2-DOF rigid linkage system is built, firstly. Next, a robust controller is designed. Then, the Lyapunov function is constructed to verify its stability. Finally, detailed simulations with some comparisons demonstrate the effectiveness of the proposed method.

According to the structures and functions of the hexapod robot, this paper explores a method to complete turning with constant radius based on the triangle gait and center of gravity trajectory tracking. The gravity trajectory model of hexapod robot in the rotation process is reversely established with predefined rotation angle and turning radius by tracking the center of gravity of the robot. Then the gravity trajectories of the hexapod robot are simulated and the deviation errors between the ideal trajectories and planed trajectories of the center of gravity are investigated. Also, the maximum gait rotation angle model is established according to the static stability margin model. The experiments on turning performance with fixed point or constant radius of the hexapod robot are performed and the turning performance of hexapod robot is studied with different gait rotation angle and turning radius by analyzing the work space of foot of robot. The simulation and experiment results prove the reasonability and validity of turning gait planning method. The hexapod robot is flexible to turn at any radius and it moves more smoothly and steadily when the planning gait angle is smaller than the maximum gait angle.

In order to obtain the vibration law of elliptic gear pair and realize its stable and efficient transmission, the nonlinear dynamic characteristics of elliptic gear were studied based on the analysis of the inherent characteristics of elliptic gear. Based on the theory of gear dynamics, a nonlinear dynamic model of elliptic gear with time-varying meshing stiffness, backlash, static transmission error and viscoelastic damping is established. The nonlinear dynamic equation of elliptic gear transmission system is solved by the fourth-order variable step Runge-Kutta numerical method, and the displacement response, phase trajectory and Poincaré mapping of the system are plotted. The effects of excitation frequency, damping ratio, time-varying mesh stiffness, and internal excitation parameters on the dynamic response of the transmission system are obtained. The establishment, solution and parameter analysis of dynamic model of elliptic gear pair can provide a theoretical basis for subsequent dynamic design, vibration response trend prediction and noise reduction under different parameters.

In gear transmission mechanism, stiffness is undoubtedly an important parameter, and considering the ubiquitous lubricant in mechanical system, it is necessary to study the contact stiffness under the condition of mixed lubrication. It is certain that the gear contact stiffness considering lubrication is the result of a multi-factor combination. In real working conditions, the gear contact stiffness is time-varying due to the variation of meshing force，the influence of rough interface and the presence of lubricant. In fact, the mixed lubrication solution is crucial. Once the film thickness and pressure distribution under mixed lubrication are known, the final result can be obtained by substituting the obtained results into the calculation expression. In order to study the contact stiffness of gears under mixed lubrication conditions, a calculation method is proposed. First, the motion parameters and normal contact force during the gear meshing process are determined. Second, the mixed elastohydrodynamic lubrication method is used to obtain the film thickness and pressure distribution on the meshing rough tooth surface at different moment. Finally, the obtained film thickness and pressure distribution are brought into the contact stiffness calculation formula to get the contact stiffness of gear at different times. The influence of different working conditions on the contact stiffness of gear is further discussed, and the contact stiffness of smooth surface is compared with that of rough surface. The results show that the speed and load have obvious influences on the contact stiffness. The higher the gear speed, the smaller the contact stiffness, and the smaller the applied load, the greater the contact stiffness of the gear.

The forming process of some reinforcement plates below the windows of railway vehicles was stimulated and analyzed using the general finite element software Autoform. The influences of the process parameters such as drawbead, blankholder force and die-clearance were investigated. The results show that the split defect of sheet is caused by uneven material flow, and the wrinkle defect is caused by the assembly of materials in corners, which can be eliminated through decorating additional drawbeads in the corners. The optimal combination of parameters was found by orthogonal experiments, which could further control the split and the wrinkle defects. The optimized parameters are force factor of drawbead 0.35, constant force of the blankholder 800 kN and the single-side die clearance 0.20 mm. Compensation to the die face based on springback can significantly control the contour accuracy. The most optimal coefficient is 1.1 times of the springback amount. Forming experiments were conducted according to the simulation results and the qualified product was obtained, which proves validity of the proposed defect controlling methods.

The double-sided of friction stir butt welding was carried out on the 6082-T4 aluminum alloys with thickness of 84 mm , and artificial aging (180 ℃×5 h) was applied after welding. The microstructure and mechanical properties of welded joints along the thickness direction were studied. The results indicate that the microstructure of the Welding Nugget Zone (WNZ) is fine equiaxed grains. From the surface of the plate to the center of welding seam, the grain sizes are 16 μm, 13 μm, and 5 μm, respectively, and the proportions of high angle grain boundaries are 77.2%, 76.3%, and 72.5%, respectively. The strengthening phase of WNZ is mainly "GP zone" and β″. The grain of the Thermo-Mechanically Affected Zone (TMAZ) is elongated and there is a high density dislocation. The microhardness in the thickness direction indicates that the hardness curve of the center overlap area of the weld is "V" type, the lowest hardness value appears in the double-sided welding overlap area, while the hardness curve of the other area is "W" type,. The samples are all broken in the area where TMAZ and Heat Affected Zone (HAZ) meet. The tensile strengths from the surface to the center overlap in the thickness direction are 211 MPa, 201 MPa, and 180 MPa, which gradually decrease. The center overlap zone has the lowest tensile strength, but its elongation is the highest, which is about 69% of the base metal. The fracture surfaces were distributed with dimples of different sizes, and fractures in all tensile specimens were ductile fracture.

In order to study the super-bainite structure transformation of 70Si2Mn2CrMo steel after isothermal heat treatment at different temperatures, the precipitation of carbide and its mechanical properties were studied. The temperature and type of carbide precipitation were determined by the analysis of the microstructure and mechanical properties of the sample. It is shown that the precipitation of carbide reduces the carbon content in the overcooling austenite, resulting in low stability of the steel and the volume fraction of retained austenite in super-bainite is reduced. Compared with the sample of no carbide precipitation at 220 °C isothermal heat treatment, the tensile strength of the sample steel decreased by 11%, the strong plastic product decreased by 16%, and the fatigue cycle fracture times decreased by 55%, at 245 ° C isothermal heat treatment.

A novel Set Covering (SC) model with variable coverage radius was proposed to design maintenance network for urban rail transit system in the context of networked maintenance. Optimization Biogeography-based algorithm was exploited to solve the SC model as its combinatorial optimization programming is highly similar with covering rule and maintenance mechanism. Experimental example analysis showed that the proposed SC model and algorithm are effective to meet with network-wide requirements by a direct tradeoff between the covering radius and maintenance response time. Besides, maintenance capacity and variable coverage radius of each maintenance point affect both the maintenance timeliness and resource utilization of maintenance unit.

In order to solve the unidirectional traffic congestion due to uneven road traffic capacity, The tidal lane setting conditions and coefficient of direction uniformity were analyzed. The tidal lane of bi-level programming model is established from the perspective of network system. In the model, the upper-level is applied to optimize the sum of the system delay and tidal lane utilization ratio, and the lower-level is designed by user equilibrium allocation model whose path selection behavior conforms to the Wardrop principle. The iterative algorithm integrating a genetic algorithm and a Frank-Wolfe algorithm is used to solve the lower and upper models. A case study is implemented to test the efficiency of the model, the coefficient of direction uniformity and road saturation before and after optimization are compared. The results show that the model can reasonably alleviate the phenomenon of tidal traffic and reduce the total delay of the road network system.

In order to explore the influences of built environment characteristics on commuting mode choice, a multilevel binary logistic model considering spatial heterogeneity is establsihed, and Changchun is chosen as the empirical case in this study. The influences of the variables at individual level and traffic analysis zone level are considered simultaneously in the model. The model parameters are calibrated using HLM software. The result shows that the spatial heterogeneity of commuting mode choice significantly exists. At the individual level, gender, age, education, hukou, household income, household car ownership and commuting distance have significant influences on commuting mode choice. At the traffic analysis zone level, residents living in areas with higher land use mix, transit station and intersection density have a lower probability of commuting by car. Additionally, residents living farther from Central Business District (CBD) tend to have a higher probability of driving to work.

In order to investigate the personal characteristics in heterogeneous pedestrian crowds during evacuation, an optimization-based evacuation model is proposed. The concepts of visual area of each agent and personal sensitivity to the space availability are introduced. A side preference of each pedestrian is implemented based on traffic social norms. The criteria for the evaluating of space availability are established to depict the personal heterogeneity from the perspective of both behavior and decision-making. The model was employed to simulate overtaking behavior and lane formation and the phase change of pedestrian lanes in heterogeneous pedestrian crowds was observed experimentally. The model was validated by comparing the simulation results with experiment date and with the results obtained by other evacuation model. The fundamental diagram of heterogeneous crowds was also investigated. The results show that the proposed model could simulate reasonably the personal behavior as well as the self-organization phenomena in heterogeneous crowds, thus providing the reasonable and effective strategies for crowds management in emergent situation.

By using bridge inspection records in Shanghai urban bridge management system, this paper established a probabilistic prediction model of bridge performance deterioration based on survival analysis. At the same time, Weibull distribution functions are used to describe the performance decay behavior of various bridge components in different condition states. The results show that the current urban bridges in Shanghai have a relatively short duration at condition rating A and B, and the decay speed of the deck system and superstructure is higher than the substructure. Applied a practical example of network-level bridge decay prediction from 2016 to 2018, the differences between the regression analysis, Markov chain and survival analysis method are compared. It is verified that the survival analysis model has higher prediction accuracy.

In order to improve the health detection results of bridge structures, a health detection model of bridge structures based on data mining technology is designed to solve the problems of large error and poor detection efficiency in the current health detection model. Firstly, the health data of bridge structure is collected by wireless sensor network, and the data is processed by kernel principal component analysis, which eliminates the redundancy of bridge structure health data and reduces the detection scale of bridge structure health. Then, the support vector machine is used to learn the health data of bridge structure. The parameters of bridge structure health detection model determined by particle swarm optimization algorithm are introduced to establish the optimal bridge structure health detection model. Finally, the effectiveness and superiority of the bridge structure health model are tested on the platform of Matlab 2017. The results show that the model achieves high precision bridge structure health. The health detection results show that the time of bridge structure health modeling is reduced, and the efficiency of bridge structure health detection is improved. Moreover, the overall performance of the proposed bridge health detection model is obviously better than that of other bridge health detection models. The proposed model provides an effective tool for bridge structure health research.

To reasonably and dynamically predict the extreme stresses of service-bridge structure, the monitored extreme stress data is taken as a time series, a new data assimilation algorithm about bridge extreme stresses prediction is proposed. The dynamic nonlinear model is built with the monitored extreme stress data of bridges, and K-MEANS algorithm and Expectation Maximization (EM) algorithm are introduced and embedded in the Gaussian Mixed Particle Filter (GMPF), then the Improved Gaussian Mixed Particle Filter (IGMPF) prediction approach can be obtained. The structural stresses are dynamically predicted based on the monitored extreme stress data. The monitored stress data of an actual bridge is provided to illustrate the feasibility of the proposed method, which shows that the improved algorithm is more feasible and accurate than the other algorithms.

In order to accurately analyze the frequency and mode shape of steel-concrete composite beam considering the shear-slip effect, the displacement function of the steel-concrete composite beam is proposed according to the basic idea of classical dynamics and the bond slip theory. Based on the energy method, the free vibration equation of composite beam considering shear-slip effect is derived and the natural frequency and its mode shape are obtained, which solves the problem of considering shear-slip at the interface of steel-concrete composite beam. The frequency and mode shape of the testing beam are measured by laboratory test, and the simulation analysis of steel-concrete composite beams is carried out based on ANSYS. The measured value and simulation value are compared with the theoretical solution. The results show that the theoretical solution of the frequency and mode shape of the steel-concrete composite beam is correct and reasonable considering the shear-slip effect. It is very necessary to take the shear-slip effect into consideration in the practical composite beam engineering.

In order to investigate solidification effect to coarse-grained soil in Changchun by sisal fiber and ionic soil stabilizer with cement, Sisal fiber cement reinforced soil sample was prepared in which the fiber content is 0.6%, fiber length is 1 cm, stabilizer content is 0.03%, and cement content is 5%. The tests on the road performance indexes, such as the unconfined compressive strength, indirect tensile strength, frost stability, etc., are carried out systematically. Experimental results indicate that the soil stabilized by sisal fiber and ionic soil stabilizer with cement has high early stage strength, well flexure-tension resistant performance and well frost stability. Such sisal fiber cement reinforced soil is especially suitable for Changchun and any other regions where the climate and sorts of soil are similar.

In order to provide reference for the anti-shear design and construction of asphalt pavement layer, the mechanical frictional strength between layers of asphalt pavements with different grades of structural layers was studied based on the structural layer combination of existing asphalt pavements in this study. Firstly, the theoretical model of mechanical frictional resistance between asphalt pavement layers is established based on the fractal theory, and the mechanical frictional strength characteristics of asphalt pavement with different grading structural layers combinations are analyzed. Furthermore, the shear tests of asphalt pavement with different grading structural layer combinations were carried out in order to verify the reliability of the theoretical model. The results show that the interlayer surface morphology is greatly affected by the gradation of asphalt mixture. Among them, the gradation combination type AC-13/AC-16 has the largest contact area, followed by AC-13/AC-20 and AC-16/AC-20. The mechanical frictional strength between layers is greatly affected by the combination of upper and lower gradation structure layers under the same load, and the gradation structure layer combination type AC-13/AC-20 has the largest interlayer mechanical friction strength, followed by AC-16/AC-20 and AC-13/AC-16. The theoretical value of the mechanical frictional strength among the interlayers is fitting to the experimental value at the temperature of 20 °C, which indicates that the theoretical model of the mechanical frictional strength among the asphalt pavement interlayers has certain reliability and applicability under this condition.

In this paper, based on the experiment conducted previously, failure mechanism and bearing capacity of strengthened specimens were analyzed theoretically. The relationship between the average crack spacing and the circumference of steel wire mesh was established, which can be used for quantitative analysis of the layers of steel wire mesh and the average crack spacing; The equation of transverse deflection curve of specimens with different layers of wire mesh was well fitted by half-wave curve; It was analyzed and verified that the reinforced specimens meet the plane section assumption during the deformation process for different load levels; Based on the strip method, the MATLAB program was used to calculate the bearing capacity of the HTRCS-reinforced RC eccentric column. The error was less than 5% compared with the experimental value. Therefore, it is reasonable and feasible to calculate the bearing capacity by the strip method.

The resilient modulus (MR) is an important parameter to characterize the elastic support performance of subgrade. MR is significantly affected by subgrade limited moisture content fluctuation after traffic opening. Soil-water characteristic curve (SWCC) tests were conducted to investigate the relationship between MR and degree of saturation of the compacted and unsaturated clay soils. Repeated load triaxial (RLT) tests were carried out to obtain MR under three moisture conditions: different moisture contents, drying or wetting path and different moisture fluctuations, to investigate the correlation between MR and matric suction. The prediction model of MR under moisture fluctuation was proposed based on the matric suction. Test results show that the MR has a good non-linear relationship with matric suction. The MR of the drying path is greater than that of wetting path under the same moisture content. With the number of moisture fluctuations increases, the dynamic MR can be firstly decreased by 23%~37% when the moisture fluctuation is 1~2 times, then MR gradually stabilizes. The influence of the frequency and amplitude of moisture fluctuation on the dynamic MR can be considered simultaneously in the proposed prediction model, and the model has higher predicting accuracy compared with the models depend on degree of saturation.

Three dimensional (3D) modeling of some complex pile composite foundations in high speed railway can be very complicated and time-consuming. So it is a common way to simplify 3D models into two dimensional (2D) models in current research, however, the applicability of different 2D modeling methods remains unclear. In this research, taking Ji'nanxi station in Beijng-Shanghai high speed railway as an example, five different 2D models are established to study their applicability by comparing the results of 2D models with that of 3D models and site measurement data. The study shows that 2D models can provide acceptable results for the development of settlements, stress of pile and soil, as well as lateral displacements. The method which remains the same elastic module and area replacement ratio yields the best results out of all 2D models. But a 3D model is necessary for the generation and dissipation of excess pore water pressures in foundation and bending moments of pile close to the toe of embankment, because 2D models give incorrect results.

To solve the problems of uneven overall force, low shear bearing capacity and inadaptability to large deformation of anchor bolt in deep roadway supported by lengthened or full-length anchor bolt, a Full-length Anchorage (FLA) support method with High Pretension Post-tensioning (HP-PT) is proposed in this paper. By establishing the mechanical model of FLA support with HP-PT method, the mechanical characteristics and bearing capacity of the anchorage section of FLA support with HP-PT method are calculated and analyzed theoretically, and compared with the traditional lengthened and FLA support method. The results show that the FLA support with HP-PT method has the advantages of both high pretension support and FLA support. Compared with the traditional lengthening and support method, the FLA with HP-PT support method makes the distribution of shear stress more gentle; it is conducive to the diffusion of pre-tightening force in confining pressure, enlarges the range of compressive stress zone of surrounding rock, improves the characteristics of anchored surrounding rock; and using high Pre-tightening Force pallet can form a more effective supporting structure of anchored surrounding rock.

The research was conducted to comprehensively study the efficiency and effectiveness of bacteria-based concrete repair technology. In the research, Sporosarcina pasteurii were applied as working bacteria in healing agent, the calcium source was selected by analysis of product crystalline phases. The prepared healing agent was used to repair cracked concrete specimens. After repair computed tomography was applied to evaluate the physical sealing. Specimens with and without cracking and specimens with crack-sealing were processed, and a series of durability tests were conducted to study the sealing caused rejuvenation, including water absorption, chloride penetration resistance, frost resistance and sulfate attack resistance. Results show that calcium nitrate is suitable as calcium source, which reacts with hydrolysed urea to entirely seal the crack surface and can fill more than half of the crack space. The impermeability of the cracked concrete is greatly rejuvenated after repair, and both frost resistance and sulfate attack resistance are compensated in certain scale. This research has recommended calcium nitrate as calcium source for bacteria-based mineralization, evaluated sealing efficiency, and importantly, confirmed a good rejuvenation in concrete durability.

The corrosion of glass fiber and time-dependent change of mechanical properties of glass fiber reinforced Portland cement (GRC) with or without admixture were studied by accelerated aging method with 80 ℃ hydrothermal curing. The results show that the time-dependent change of GRC mechanical properties is caused by the combined effect of cement mortar strength growth and glass fiber corrosion damage. With the extension of curing time, on the one hand, the strength of cement mortar with fly ash keeps increasing; on the other hand, fly ash inhibits the corrosion of glass fiber. As a result, the bending strength of GRC with fly ash keeps rising despite the corrosion of glass fiber. Accelerated aging test showed that the inhibition effect of fly ash on glass fiber corrosion is better than slag. It exhibited a brittle behaviour with slight corrosion of glass fiber. Hydrating phases within and around glass fibers will lead to the loss of toughening effect. So, it is more effective to evaluate degradation of GRC by the change of GRC toughness than by the change of strength.

In order to study the mechanical characteristics of the laminated slab with shear keys, a static test with 7 slabs was carried out and an supplementary analysis was made by finite element method. The results show that different types of shear keys can ensure the reliability of the interface of the laminated slab to enable its mechanical characteristics close to the cast-in-place slab. The concrete is firmly bonded between cast-in-place layer and precast layer, and between shear key and precast layer, which has a good integrity. The simply supported laminated slab with shear keys can be approximately calculated according to the once force bearing component when the span is less than 3.2 m. When the contact between the precast base plate and the cast-in-place layer is made in a friction manner, the yield load of the laminated slab increases and the yield displacement decreases with the increases in the number of rows of shear key, the number of columns of shear key and the cross-sectional area. The number of columns of shear key has a more obvious influence. When the above three factors increase to a certain extent, the influence is no longer obvious. After a certain number of shear keys are arranged, the strength grade of the concrete of shear key, the strength grade of the concrete of cast-in-place layer, and the friction coefficient have little influence on the bearing capacity of the laminated slab and the yield displacement. Finally, the stiffness formula of the laminated slab with shear keys is established.

The general method to sharp the underwater video image is vulnerable to provoking issues such as image distortion, noise amplification, and the flicker and jump of adjacent frames in video playback. To overcome these disadvantages, a single color method based on color space as well as the underwater image sharpening method and an underwater video sharpening method based on spatiotemporal information fusion are proposed. In the process of clearing the single underwater image, the phenomenon that the transmittance is estimated to be large in traditional method is polished, and the combination of dark channel prior and color saturation is adopted in order to polish the background light. For the phenomenon of flicker and jump in adjacent frames in video playback, the time and space information are fused, and the more stable transmittance is estimated by interpolation and averaging. The experimental results show that the proposed underwater video sharpening method works effectively in the clearing of underwater video images, resulting in well-processed continuity and smoothness of the video.

In order to manual localization and quantitative analysis of stroke lesions is time-consuming and lacks consistency. This paper proposes a multi-scale U-Net deep network method to segment high density sign of ischemic stroke from non-enhanced Computed Tomography (CT), and use the Dice loss to train the model to combat the class imbalance in the image. Experiments show that the model can automatically learn salient features of high density sign in an end-to-end data-driven manner, effectively segmenting small lesions.

Due to the imbalance of KG data and the difficulty of training, that random sampling of training data may make it difficult for embedded models to converge rapidly. Therefore, in this paper, an adaptive method for sampling of training data is proposed. The training data are grouped according to the different relationships. In the sampling process, a group is determined according to the probability, and then an instance is randomly selected from the determined group for training. At the same time, according to the training effect, the probability of each selected instance is adjusted adaptively. Experimental results show that adaptive grouping filter achieves better results in link prediction tasks, and enables the embedded model to converge faster and better.

A sensor cloud intrusion detection algorithm based on parallel discrete optimization feature extraction and machine learning is proposed in the fog computing model to overcome the large-scale, high dimensional data and variable intrusion behavior of sensor cloud. First, on the basis of defining the optimal feature evaluation index, the parallel discrete optimization feature extraction framework is constructed to effectively reduce the data dimensionality and improve the robustness of the feature extraction process. Second, a new discrete optimization algorithm (DOA) is designed, and the DOA implementation process is given according to the characteristics of engineering optimization problem. As DOA is proved to converge to the global optimal solution, the best feature combination is extracted. Finally, sensor cloud intrusion detection is carried out by using the best feature subset and the distributed fuzzy clustering technology. The intelligent iterative evolution method and adaptive clustering strategy are introduced to improve the performance of fuzzy clustering algorithm. Experimental results show that the proposed algorithm can effectively give intrusion detection results. Compared with other detection algorithms, the anomaly detection accuracy and missed detection rate of the proposed algorithm are significantly improved, and it has strong anti-noise ability.

Most of the state-of-the-art Toeplitz matrix reconstruction algorithms for direction-of-arrival (DOA) estimation of coherent signals use partial correction or covariance matrix information from the received signals, which leads to the incomplete information utilization, and denoising preprocessing is needed in some methods. To overcome this disadvantage, a modified algorithm is presented by adopting the entire correlation information of the received data from all array sensors to reconstruct a set of Toeplitz matrices. After Hermitian transpositing and forward/backward averaging, the equivalent full rank covariance matrix is utilized for coherent signals DOA estimation combined the ESPRIT algorithm with low computation. The presented method avoids denoising processing and the simulation results show the effectiveness of the proposed method.

Traditional leader-follower formation controller can hardly obtain the data of the leader vehicle accurately and its parameters may be uncertain due to the influence of external interference. To solving this problem, this paper designed an adaptive feedback linear controller based on variable estimation and proposed an improved method based on Vehicle to Vehicle communication (V2V). Firstly, the accuracy of relative distance is improved by variable estimation. Then, the information accuracy of leader vehicle is guaranteed by using V2V technology. In order to verify the effectiveness of the algorithm, a co-simulation experiment is made using VS2010 and Simulink. The results show that the formation method based on V2V and adaptive control principle can effectively complete the formation task with small errors and convergence. This method provides certain application value for the development of intelligent connected vehicles.

This paper addresses the detection and tracking of pedestrians in indoor environments by using distributed Two-dimensional Laser Range Finders (2D-LRFs). We first proposed a novel algorithm to calibrate multiple 2D-LRFs based on a virtual dihedron such that all the 2D laser data from different 2D-LRFs can be mapped into a reference coordinate system. Then, based on the integrated 2D laser data, we proposed Laser Gaussian Model (LGM) to model the background and the Density-based Spatial Clustering of Applications with Noise (DBSCAN) for pedestrian detection. Finally, the detected pedestrians were tracked across different views of the multiple LRFs by Kalman filter. The proposed methods were tested and validated by using different 2D-LRFs in real indoor environments, and compared with existing algorithms in terms of the view angles and the recognition rate among different illumination conditions. The results demonstrate that the proposed distributed 2D-LRFs can monitor the indoor environments with very large view angles and unaffected by lighting conditions. The proposed methods can detect and track moving pedestrians accurately and reliably for indoor surveillance.

In order to solve the problems of low threshing rate and high damage rate in wheat threshing, standard bow teeth for wheat threshing were designed Innovatively, and the threshing interface was analyzed. The new rigid flexible coupling bow teeth wheat threshing test bed was designed. The quadratic regression orthogonal tests were carried out to compare the performance of the new bow teeth with that of traditional wheat threshing bow teeth. The results show that the damage rate using the rigid flexible coupling bow teeth is significantly reduced, and the maximum reduction is 1.04%, the threshing rate using the rigid flexible coupling bow teeth was significantly increased, and its maximum increase is 4.64%. The influence degree of test factors on the damage rate of the rigid flexible coupling bow teeth is successively from large to small: drum speed, feeding amount and threshing clearance. Regression model of damage rate of rigid flexible coupling bow teeth was established. The optimal operation parameter combination for minimal damage rate is obtained by response surface analysis, which drum speed is 350 r/min, threshing clearance is 30 mm, and feeding amount is 6 kg/s. The influence degree of test factors on threshing rate of rigid flexible coupling bow teeth was successively from large to small: drum speed, threshing clearance and feeding amount. Regression model of threshing rate of rigid flexible coupling bow teeth was established. The optimal operation parameter combination for maximal threshing rate is obtained by response surface analysis, which drum speed is 600 r/min, threshing clearance is 10 mm, and feeding amount is 3.5 kg/s.

Chopping is one of the most important working processes of forage maize harvester. However, high energy consumption and poor mincing quality seriously restrict the effect of chopping process. The specific energy consumption and the standard grass length were directly affected by working parameters of chopping devices. Therefore, working parameters optimization test was carried out on chopping devices of forage maize harvester. The cutter head speed, feeding speed and feeding inclination angle were selected as the test factors. The better levels of the three test factors were obtained by single factor experiment. The better levels of cutter head speed ranged from 1 000 to 1 200 r/min. The better levels of feeding speed ranged from 3 to 4 m/s. The better levels of feeding inclination angle ranged from 8° to 10°. Based on single factor test results, the optimal combination of three test factors and regression model were obtained by orthogonal test. The optimal factor combination for minimum specific energy consumption was cutter head speed 1 005 r/min, feeding speed 4 m/s, feeding angle 8.4°. The optimal factor combination of maximum standard grass rate was the cutter head speed 1 200 r/min, the feeding speed 3.5 m/s, and the feeding angle 8.5°. The optimal factor combination of chopping comprehensive weighted index was the cutter head speed 1 200 r/min, the feeding speed 4 m/s, and the feeding angle 8°. The regression models were verified by field test. The relative error of regression model of specific energy consumption was 5.23%. The relative error of regression model of standard grass rate was 3.15%.The results show that the regression models were reliable.

To increase the soil temperature to ensure that the production of potato, the straw was used to cover the soil when planting potato in the south of China in winter. When the straw-covered winter potato is harvested, there exist several problems such as big digging resistance, easy blocking, difficult separation of straw, and low excavation rate and high injury rate of potato. In order to solve these problems, a harvester for winter planting potato with a straw separation device is developed. The harvester is composed of divided shovel, rod elevating chain, straw separating mechanism and oscillating screen which can finish potato digging, separate potato from soil and straws , orderly placement of potato in one step. This article described the main structure and working principle of the machine. In addition , according to theorem of vector projection, kinetic energy and kinematics, the structure of key parts were designed and the parameters were determined. To evaluate the performance of the harvester, field experiment was carried out, in which the obvious rate of potato, injury rate of potato and reliability were taken as the indexes and the machine forward speed, tilt angle of sieve plate and number of lifting lever were taken as the factors. The multi-objective optimization method was adopted to analyze the experimental data. The results show that when the machine forward speed was 0.4 m?s ^-1, working finger speed was 3 m?s ^-1, and the number of working pole was 6, the obvious rate of potato was 99.5%, injury rate of potato was 4.2%, the reliability was 80.4%. The comprehensive performance index was better and meet the using requirements of potato harvester.

To solve the problem of poor impact resistance of robot leg and foot system, a bionic tensegrity mechanical leg was developed based on the principle of biological tensegrity. Flexible materials were employed to simulate the biological joint ligament and tendon, instead of using rigid hinge joint. Finite element simulation results show that the bionic tensegrity mechanical leg has better impact resistance than the traditional mechanical leg. The material sensitivity analysis results show that during impact, the flexible member in the bionic tensegrity leg absorbs the impact energy effectively through deformation, reduces the impact strength, and improves the stress distribution state of the rigid member. Within the scope of the study, keeping the elastic modulus of bionic tendon material as constant, the smaller the elastic modulus of the bionic ligament, the stronger the anti-impact and anti-bending resistance of the bionic leg. Similarly, when the bionic ligament is kept constant, the larger the elastic modulus of the bionic tendon, the better the anti-impact and anti-bending resistance of the bionic leg. Furthermore, this project provides important theoretical basis for the innovative design of robot leg-foot system.