Abstract:To further improve the analysis methods of structural robustness, redundancy, and vulnerability, and to obtain the relationship between structural resistance and external load effect, optimization and reinforcement measures can be implemented for the weak or vulnerable parts of a structure to reduce the loss caused by damage or even safety accident due to the lack of structural resistance. Firstly, by reviewing the research progress of structural robustness, redundancy, and vulnerability and comparing different expressions of the current evaluation indexes, the essence of structural robustness, redundancy, and vulnerability were pointed out, and a new evaluation index based on strain energy was proposed. A further study on the relationship between structural robustness, redundancy, and vulnerability, as well as the basic influencing factors was also performed. Results have shown that structural robustness, redundancy, and vulnerability are from different fields and periods, which can reflect the resistance capacity of a structure, especially that of a damaged structure. The evaluation indexes are mostly subjectively defined by a complicated calculation process based on different levels of understanding. A widely accepted analysis method has not been established so far. Specifically, structural robustness and redundancy share similar evaluation index expression, both of which can represent the safety capacity or the remaining tolerance capacity of a structure. Structural vulnerability can directly reflect the structural failure extent, and it is inversely proportional to structural robustness and redundancy in the physical sense. Moreover, the increase in the material strength, the section size, and the structural restraint, together with the optimization of the load path, can increase structural robustness and redundancy and reduce structural vulnerability. The optimization and reinforcement measures can be implemented for the weak or vulnerable parts, thus structural damage, safety accident, as well as the loss cause by them, can be further reduced.

Abstract:To address the issue that the traffic load effects on bridges are neither independent nor identically distributed due to the influence of multiple events, the predictive method of composite generalized Pareto distribution (CGPD) was improved using joint threshold, which is robust to predict the extrema of mixture peaks over threshold (POT) using any tail approximation function. The autocorrelation coefficient informed sampling interval method, K-S test based threshold selection, and probability weight moment method were proposed to resolve the time-independent test of POTs, threshold selection, and parameter estimation in CGPD, respectively. Theoretical solutions were conducted to verify the accuracy of the improved CGPD model and its critical techniques, and the CGPD method was implemented in the extrema prediction of realistic traffic load effects on short to long span bridges. Results indicated the proposed practical techniques showed good application effect and generated accurate results, which provide strong support for the implementation of CGPD. Numerical examples showed the CGPD could precisely predict extreme values of multi-event driven samples with relative error below 3%. In contrast, the conventional single generalized Pareto distribution (SGPD) exhibits a significant deviations compared with CGPD. The realistic traffic load effects on short and medium span bridges can be categorized based on the events of number of trucks involved, but that on long span bridges can be categorized based on events in rush hours or normal hours according to the ratio of hourly traffic volume to hourly truck. The CGPD method is convenient to predict extreme load effect in any return period, whereas the SGPD method would produce significant deviation in extrema with a maximal relative error of 13.7% compared to that of CGPD.

Abstract:To investigate the complex wind environment around the tower of long span railway-highway combined cable-stayed bridge, the computational fluid dynamics (CFD) was employed to simulate the wind field above the highway deck around the tower. Based on the wind tunnel test of large scale local rigid tower-girder model the wind speed measurements at the center height of three typical highway vehicles and train were conducted, respectively, and the wind speed coefficient λ, wind speed mutation rate ξ and the wind speed fluctuation rate η were introduced to analyze the average wind speed variation and the instantaneous wind speed fluctuation. Results showed that a certain wind speed acceleration effect was observed in the flow field near the tower. The degree of wind speed variation at different heights above the deck was different, and the change of flow at center height of the medium-sized coach was more intense. Wind speed at upwind side was greater than that at downwind side, but the wind speed gradient at downwind side was larger. Due to the wind shield effect of the tower, the influenced area of the average wind speed was about 3 times the width of the tower windward surface, and that of the instantaneous wind speed fluctuation was slightly less than 4 times the width of the tower windward surface on the highway deck, whereas it was slightly larger than 4 times the width of the tower windward surface on the railway deck.

Abstract:Ticket price of high-speed railway in China is unitary and changeless, which cannot adjust passenger flow and improve revenue. Based on the analysis of passenger's sensitivity towards ticket price in different booking periods, a robust optimization model of multi-period dynamic pricing for high-speed railway was developed aiming to maximize the revenue on the basis of revenue management theory and the transportation organization characteristics of high-speed railway. Considering the uncertainty of demand function, the model was solved with a robust optimization method. Beijing-Shanghai high-speed train was taken as an example to test the effectiveness of the model. The results showed that compared with the seat allocation scheme under the unitary ticket fare, the proposed model can dynamically adjust ticket fare to regulate the passenger flow in different booking periods and improve revenue. In addition, the robustness of the model was verified by the simulation test. Compared with the nominal model, the proposed model can better adapt to the fluctuation of the demand and ensure that more tickets are sold at a higher price. The proposed model provides an optimization method for dynamic pricing of high-speed railway.

Abstract:To develop a high performance cement-based grouting materials and use it in complex stratum, the effects of sodium aluminate (SA), superplasticizer (Sp), super-absorbent polymer (SAP) and their dosage on rheological properties and bleeding of fresh cement paste were investigated. The hydration evolution of cement paste at early stage and suspension morphology of particles in different polymers system were also analyzed by heat monitoring and fluorescent inverted microscope. Results indicated that the flowability and bleeding of fresh cement paste negatively related to the dosage of SA and SAP, which were enhanced with the increase of Sp contents. The stage of hydration induction was delayed for about 1 h, then the rate of heat flow decreased significantly with the incorporation of Sp and SAP. Affected by the procoagulant of SA, the dispersion of Sp, and reservoir function of SAP, the period with high flowability (greater than 200 mm) of fresh cement paste could be controlled within 10 min, 20 min, and 30 min respectively with a bleeding ratio lower than 5% (stable slurry). Then the rheological parameters suddenly increased while the fluidity sharply decreased. Combined with microstructure test results, the evolution model was established to reveal the rheological mechanism of dispersion-absorption-rheological-hydration at early stage affected by the synergetic effects of polymers system.

Abstract:To investigate the comprehensive state of cable forces, an evaluation method considering the temporal and spatial characteristics of the cable forces was proposed. Using the bridge risk matrix decision-making method, the time index and spatial index were taken into a matrix for evaluation and policy decision. The spatial and temporal evaluation levels are divided into four levels: blue grade Ⅰ, yellow grade Ⅱ, orange grade Ⅲ and red grade Ⅳ. Time index considers both the change rate and the amplitude of the cable forces, in which the change rate of cable force was obtained by time series analysis, and the amplitude of cable force was obtained by absolute value of change rate of cable force. Spatial index mainly reflects the deviation degree of cable forces on both sides of cable-stayed bridge caused by unbalance loading and single cable damage, and was characterized by Canberra distance. Taking 7 years of monitoring data from Nanjing No.3 Yangtze River Bridge as an example, twenty long stay cables were evaluated by the temporal and spatial comprehensive evaluation method. The group cables evaluation grade table and evaluation grade distribution map were formed. Results show that monitoring cable forces conform to time series characteristics, and a linear regression model can be used to extract trend terms. The temporal and spatial evaluation levels of the cables are grade Ⅱ and above, and the main reasons are excessively fast change rate of cable force and great differences between the upstream and downstream cable forces. The evaluation distribution map provides more targeted guidance for the manual inspection of stay cables.

Abstract:To investigate the reasons of different performance of asphalt mixture, volume index and structural parameters were measured in asphalt mixtures with different flat and elongated particles content. Void ratio of asphalt mixture was calculated based on industrial CT scanning and image processing technology, and color scale was used to mark the void structure. The parameters such as area, aspect ratio-AR₁ and AR₂, mean value of spindle deflection angle, particle trend parameter-Δ and angularity were adopted to evaluate the structural characteristics of asphalt mixture. Results show that with the increase of flat and elongated particles, the volume density of asphalt mixture decreases and the porosity increases, and the void ratio calculated by industrial CT is larger than the measured. Macro-pore structure is mainly distributed in the middle and lower part of the specimens, but the voids at the top of the specimens are smaller. With the increase of the flat and elongated particles content in mixture, the aspect ratio expectation of particles-AR₁, AR₂ and angularity expectation increases, and the cross section area of coarse aggregate particle decreases, but the influences on the mean deviation of deflection angle and grain trend are not obvious.

Abstract:In order to improve the applicability of back-calculation methods of rigid pavement parameters, this research presents comprehensive analysis of three representative derived indicators of deflection basin for back-calculation of rigid pavement parameters. By systematic analysis and modelling of AREA, intertial point (IP) and Barycentric Horizontal Distance (BHD) method in the ILLI-BACK, the distribution laws of these three methods were investigated quantitatively using numerical analysis, and the nomograph of IP and regression formulas of AREA and BHD were developed respectively to improve the applicability in the practice. Taking typical rigid pavement structure as an example, the accuracy and robustness of three comparative back-calculation methods were verified. Results showed that the back-calculation were greatly simplified using the nomograph and regression formulas. The back-calculation results based on three comparative methods exhibited remarkable difference. BHD significantly improved the accuracy and robustness in back-calculation of rigid pavement parameters by making full use of measurement information at all the sensors and minimizing the fitting error.

Abstract:To investigate the adsorption mechanism of cement on emulsified asphalt and superplasticizer in cement-asphalt mortar (CA mortar), the retardation effects of superplasticizer and emulsified asphalt on cement hydration were analyzed by the result of hydration heat measured by microcalorimetry. The effects of the type and adding sequence of superplasticizer on the adsorption of cement-emulsified asphalt were studied. In addition, the in-situ observation of the adsorption between cement and emulsified asphalt under the function of superplasticizer was conducted by using the polarizing microscope. Results showed that both emulsified asphalt and superplasticizer could retard the cement hydration and evidently extend the induction, while the co-adding of superplasticizer and emulsified asphalt resulted in evident synergistic effect in respect of the induction's extension. Competitive relationship obviously existed between the adsorption of polycarboxylate superplasticizer and emulsified asphalt on cement. In the case of coexistence of superplasticizer and emulsified asphalt, the cement was adsorbed by the former in priority. When the superplasticizer was added after emulsified asphalt, the adsorbed emulsified asphalt particles could be substituted by superplasticizer.

Abstract:In order to provide reference for urban road planning and design, a traffic survey was conducted under the interruption of roadside bicycles. The influences of the number of roadside bicycles on average travel speed and cars' saturated headway of adjacent lane were analyzed, and the models between them were established respectively by regression method. Based on established models, suggested adjustment factors were given to calculate possible capacity of urban arterial road segment, and case study was conducted. Thresholds of the number of roadside bicycles were presented to evaluate LOS (level of service) and set separate facilities on urban arterial road segment. Results show that average travel speed decrease and cars' saturated headway increases with the increasing of the number of roadside bicycles, and the quadratic function relations between them is observed. The greater the number of roadside bicycle, the higher road design speed, the smaller the adjustment factor, indicating that the influence of roadside bicycle on road capacity is greater. The higher the design speed, and the lower the threshold of the number of roadside bicycles when LOS is the same, showing that the effects of roadside bicycle on traffic operation is greater for urban road segment with higher design speed.

Abstract:The paper is intended to reveal the basic laws of temperature field, water field and amount of frost heave inside the pavement structure, and to provide the theoretical basis for the prevention and cure of uneven frost heave. The test chamber of uneven frost heave of pavement structure was originally designed. The model tests of external water infiltration and uneven frost heave of pavement structure were conducted. The numerical simulation of the three-stage coupling of hydro-thermal-stress was realized on the basis of the targeted secondary exploitation of ABAQUS. The comparison of numerical simulation results and model test results were discussed from three aspects, i.e. temperature field, water field and amount of frost heave. The results showed that: the model test intuitively simulated the phenomenon of faulting of slab ends between runway and the shoulder. It illustrated that the cause of faulting of slab ends is the uneven frost heave of the runway and the shoulder. The basic development laws of uneven frost heave of pavement structure were revealed objectively. The external water infiltration has a great impact on water field redistribution. Uneven frost heave of pavement structure is the result of the coupling of temperature field and water field inside pavement structure. The cooling rate and temperature gradient impact on the water migration and accumulation, and in turn, the water field redistribution affects the delivery of temperature. The numerical simulation results were in good agreement with the model test results, both of which were consistent with the actual. The correctness and applicability of the numerical model were verified. The combination of the objective advantages of model test and the comprehensive advantage of numerical simulation contributes to in-depth research on the uneven frost heave of other structures in cold region.

Abstract:In order to evaluate the damage of steel structures induced by earthquake, this research investigated the coupling relation between the ultimate plastic deformation and low-cycle fatigue life as well as the cyclic softening behavior of structural steel. The repeated high strain loading experiments were carried out on low carbon steel Q345qC, and the low-cycle fatigue life and cyclic softening behavior were studied. By analyzing the relationships between the bearing capacity deterioration and the dissipating energy density, the modification of the bounding surface radius and center and cyclic softening were introduced to the two-surface constitutive model. On this basis, the mechanical behaviors of a steel bridge pier under cyclic loading were investigated by employing the modified two-surface constitutive model, and the effects of material cyclic softening on the bearing capacity of the steel bridge pier were analyzed and discussed. Results show that the structural steel Q345 has good ductility and anti-low-cycle fatigue property. No evident coupling relation between ultimate plastic deformation and low cycle fatigue life of the steel was observed in the experiments. Cyclic softening is more apparent at a larger plastic strain state. The modified two-surface constitutive model is capable of simulating the cyclic softening behavior of the steel in a very satisfactory manner. The bearing capacity of the steel bridge pier under cyclic loading or in earthquake decreases slightly when material cyclic softening is considered.

Abstract:To introduce the green traffic idea and the bus priority idea into the modeling strategy of signal timing optimization for intersections, a multi-objective signal timing optimization model varying with the phase effective green light time was proposed by considering the per capita delay and per capita CO emissions as the indexes. The bus deduction coefficient was introduced into the delay per capita to overcome the negative effect of absolute priority on private car. The fuzzy compromise method was used to transform the two objective functions of different dimensions into a single objective function, and to determine the values of two dimensions lie in (0, l). Fuzzy preference method was used to determine the membership function weights in the single objective function. The improved PSO (particle swarm optimization) which combines the SAPSO (self-adaptive particle swarm optimization) and the AsyLnCPSO (asynchronous learning-factor changing particle swarm optimization) were used to solve the single objective function based on the MATLAB software platform. Finally, the model was applied to an actual case and the target values were compared and analyzed. Results showed that the per capita delay reduced by 0.94s and decreased by 3.87% after optimization. The per capita CO emission reduced by 1.25g and decreased by 12.74%. The optimized signal timing scheme has an optimal effect on delay and emission, and the validity of the model was observed.

Abstract:To effectively grasp the dynamic information of key regional population aggregation, guarantee timely dispatching of regional population, and prevent group security accident, this paper took Guangzhou Railway Station hub area as an example, and obtained real-time statistics of its regional population by carrying out information processing based on massive mobile phone signaling data and mapping the data to the study area using geographic information system. Meanwhile, it analyzed the change of the population in this area during Spring Festival, and summarized the periodic variation characteristics of the regional population. Based on this, this paper constructed the k value adaptive calculation model with minimum absolute percentage error, and built the k-Nearest Neighborhood algorithm based on the mobile communication data to predict urban hub traffic. The algorithm was tested under the traffic conditions on weekends and weekdays near Guangzhou Railway Station. The results showed that the average absolute percentage error (MAPE) of the prediction algorithm was around 5%. It is more accurate to effectively predict regional population.

Abstract:To investigate the relation between people's travel behavior and urban traffic congestion, and provide technical support to alleviate urban traffic congestion, a data-driven source localization approach was constructed based on high-coverage-rate low-precision mobile phone data and high-precision taxi GPS data. Travel demand and traffic condition information was obtained by personal mobile phone data and taxi GPS data, respectively. Mobile phone data and taxi GPS data were combined to estimate origin-destination matrix, conduct traffic assignment, and dynamically locate traffic sources of road segments and the congestion sources of the city. Result showed that a majority of traffic flow was generated by a few sources, and the sources became more concentrated when traffic jam occurred. Urban congested sources were affected by commuting behaviors, and exhibited different characteristics during morning and evening peak hours. Traffic source location by data fusion can uncover the internal mechanism and evolution law of traffic congestion, and help in making target policies dealing with traffic congestion.

Abstract:To investigate the relationship of surface energy between mineral filler and its chemical compositions, the grey correlation method and principal component analysis method were employed to quantitatively analyze the relationship model measured by capillary rise method. Results showed that measured surface energy parameters of mineral filler agreed with the value calculated on the basis of chemical composition surface energy parameters. A quantitative model related to the changing mineral filler surface energy parameter, chemical composition content and the unchanging chemical composition surface energy parameter was proposed. The surface energy of mineral filler can be determined by this model when the chemical compositions are given. All of the results can provide theoretical direction to further study on mineral filler surface energy for road engineering.

Abstract:To make the most of control accuracy and fast response of in-wheel motors and improve the stability of anti-lock brake system (ABS) of in-wheel motor driven electric vehicle, a design method of anti-lock controller based on the improved linear quadratic optimal control algorithm was proposed. A vehicle longitudinal dynamics model was established. The coordinated control strategy of composite braking system was applied in examining the reason for the failure of the general linear quadratic optimal control algorithm in the design of anti-lock controller. An improved linear quadratic optimal control algorithm was proposed to design the anti-lock controller through adding some virtual damping and infinitely small terms in the design process of Riccati function, based on which a anti-lock brake was subsequently designed. The control result of the proposed controller was compared with the control result of general sliding mode controller under three different road conditions with low, middle and high adhesive coefficients. Results showed that the proposed improved linear quadratic optimal control algorithm can achieve not only outstanding control accuracy but also fast response.

Abstract:The effect of organic carbon source on the granulation of anaerobic ammonium oxidation (Anammox) sludge was tested in two parallel SBRs by gradually increasing the concentration of organic carbon source (R1) and by adding no organic carbon (R2). Results showed that appropriate concentration of organic carbon source (< 130 mg/L) increased the amount of extracellular polymer (EPS) in the reactor and consequently accelerated the formation of granular sludge and enhanced sludge settling performance. Sludge in the two groups was granulated at 28 and 35 days and the particle sizes were 450 μm and 409 μm, respectively. However, excessive organic carbon sources (> 230 mg/L) disintegrated sludge, reduced particle size, and worsened sludge settling performance significantly. Organic carbon source with a concentration lower than 110 mg/L promoted the anaerobic ammonia oxidation by denitrification, thereby improving N-removal efficiency. In contrast, when the concentration of organic carbon source was higher than 110 mg/L, anaerobic ammonia oxidation was inhibited and N-removal efficiency was decreased. Therefore, the concentration of organic carbon source should be equal to or lower than 110 mg/L during the operation of Anammox reactor.

Abstract:In machine vision-based industrial inspections, due to changes in conveyor speed or underexposure, the resulting image may produce motion blur, affecting the detection effect. In order to remove the motion blur, a fast linear motion blur method based on RL guided filter was proposed to evaluate the blur parameters of the image first, and the image blurring direction was evaluated using the spectral map integral of the image. Using auto-correlation method to obtain the blur kernel size; then through the proposed RL-guided filtering method to quickly remove the motion blur and suppress the ringing effect, to get a clear image, proved the accuracy of fuzzy kernel estimation Compared with TPKE and HQ, the proposed deblurring method is better for noise robustness and ringing suppression. Through the experiments of real-shot images under different speeds and different workpieces, the objective difference between the objective and the deblurred dimension measurements and the speed of operation were used to prove the superiority of this method in industrial inspection. The results show that the R_PSNR and R_SIMM is superior to the contrast method, which suppresses ringing while maintaining the sharpness of the edges. At the same time, the proposed method has a smaller influence on the measurement of the size and has an advantage over a small-sized workpiece. The maximum error is 0.31 pixels.

Abstract:To solve the problems of estimation accuracy restricted by large initial estimation error and unknown noise statistics in bearings-only tracking, a divided differential filter with intelligent statistical noise estimator was proposed. An S-H intelligent noise statistical estimator was proposed according to statistical linear regression theories, and was used for optimizing measurement update step of traditional divided differential filter, thus unknown state and noise measurement were intelligently and statistically calculated. The ability of the filter to adapt to complex nonlinear functions was further improved by iteration updating. Results showed that for typical passive tracking problem in linear state function and nonlinear measurement function with relative large initial estimation errors, the proposed filter provided better performance of nonlinear estimation task compared to several mainstream adaptive filters when the statistical characteristics of the system noise and measurement noise were unknown, and it effectively enhanced tracking and guidance accuracy and guaranteed moderate level of computation load at the same time.

Abstract:In order to study the sensor of atomic interference magnetometer based on coherent population trapping principle and analyze its control variables, a mathematical model was proposed to formulate the relationship between system input variables and output signals. A mathematical model of the key variables of frequency discrimination signal contrast was also established and signal contrast experiments were performed to observe the atomic gas chamber temperature and laser input current, which are the key factors in this system. Experimental results showed that the average contrast of frequency discrimination signal was about 3%, which was in agreement with the order of magnitude of the model. The influence of the atomic gas chamber temperature and the laser current on the signal contrast was also in accordance with the results of the model. Moreover, the experiments also determined the range of dynamic operation points for an optimal signal contrast.

Abstract:In order to realize the three-axis attitude control of solar sail, this paper employed a new type of actuator, rotating panel-sliding mass, to study its control strategy. A strong robust attitude controller was proposed based on the sliding mode control theory to reduce the influence of the variable inertia moment of the spacecraft on the attitude system. In addition, the adaptive law was introduced and an adaptive disturbance-rejection control law was proposed to suppress the disturbances caused by the solar radiation pressure torque and gravitational gradient torque. Lastly, a steering law was designed for the actuator based on its dynamics to supply the control torque required by the controller, then the rotation angles of rotating panels and sliding displacements of sliding masses were calculated using the steering law. The simulation results showed that the proposed control law and the actuator steering law drove the attitude of solar sail maneuver to desired position quickly, and well resisted the influences of the variation of the inertia moment and the disturbances from solar radiation pressure torque and the gravitational gradient torque. The control torques, the angles of the rotating panels, and the displacements of the sliding masses were kept in proper amplitude range as well. The proposed control strategy effectively realized the three-axis attitude control of solar sail.

Abstract:Adaptive super-twisting sliding mode observer and controller are proposed for velocity and attitude control of fixed-wing unmanned aerial vehicle (UAV) which has been challenged by the presence of uncertainty and external disturbance. Firstly, the velocity model and quaternion-based attitude error model of fixed-wing unmanned aerial vehicle were established. Then the adaptive super-twisting sliding mode disturbance observer was designed to approximate system disturbance and uncertainty. On this basis, a super-twisting sliding control scheme was proposed to track desired commands of velocity and attitude of UVA. Finally, the stability of the system was proven by Lyapunov theory. The simulation results verified that the integrated control scheme made the UVA track desired commands fast and accurate, and had the excellent robust adaptive ability. The control strategy could also be used to quickly and steadily achieve the expected goal of unmanned aerial vehicles for different flight commands.

Abstract:To improve localization accuracy and reduce communication energy for mobile nodes of underwater wireless sensor networks (UWSNs), the localization prediction method with mobility pattern for nodes was proposed. Considering that tidal motion is the main factor to generate movement of sea water in seashore monitoring network, Gauss radial basis function was exploited as the spatial basis function to construct the node mobility pattern. Then K-medoids method was utilized to cluster and optimize the center of Gauss radial basis function and the extended Kalman filtering algorithm was adopted to predict model coefficients. Moreover, weight coefficients related to distance were designed based on the spatial correlation between the anchor node and ordinary node. The ordinary node estimated the model coefficients based on anchor node coefficients and weight coefficients, and achieved localization with estimated speed and last location. The simulation results of UWSNs in the region from 117.25°E to 132.2°E and from 24°N to 43.45°N showed that predictable localization method with mobility pattern for nodes of UWSNs (PLM_MP) had better performances. The localization coverage rate and the localization accuracy were higher than that in SLMP scheme and MP-PSO scheme, and the average communication cost was lower. It also showed that PLM_MP scheme is suitable for localization in large mobile underwater wireless sensor networks.

Abstract:To avoid the poor effect of spammer detection in traditional methods based on content and user behavior due to the increase of data and spammers' updated strategy, a spammer detection method based on sentiment analysis and quality control in microblog was proposed. In the method, the pre-processed comments in microblog were quantified by sentiment analysis. Then in the process of quality control of microblog commentary, the suspicious interval was detected according to different distribution between spammers and normal users for hotspot in varying time. Then a model for spammer recognition was established by cluster analysis. The experimental results showed that the method used the emotion score to make the emotion classification more accurately for the comment text, and then adjusted the boundary value range and time threshold range to limit the anomaly detection level. When the boundary value range increased, the anomaly detection range of the abnormal comment was increased, the tolerance was reduced and the detection sensitivity was improved. When the time threshold was expanded, the tolerance was improved and the detection sensitivity was reduced. Therefore, the appropriate choice of the boundary value and time threshold can effectively improve the accuracy of anomaly recognition which is similar to the normal commentary behavior.

Abstract:To solve the problem that the propulsion mechanism of amphibious platform is complicated and the navigation velocity is low, the first step was to study the bionic mechanism of the vector propeller and design a new type of water platform and amphibious platform based on the kinematics of basilisk lizard's feet. The bionic effects that the propeller rotates in air cavity and the platform sails in hydroplaning state with pitch10.6° angle were realized. Then, the dynamic mechanics model of water-surface platform's hydroplaning sailing was analyzed with the ЦАГИ theory, and the model of flow fluid of plan rotation was set up. Based on the analysis of the force characteristics of one blade and output of the propeller, the optimum axle height of the output and the comprehensive influence of navigation velocity and rotation velocity on driving output were obtained, and numerical calculation was validated by the test system. The results indicate that periodic output of the propeller can be deduced from the three-dimensional driving output of one blade. As the axle height rose from the water surface, the amplitudes of the lift and moment firstly increased and then decreased. The thrust decreased monotonically and the maximum values of three-dimensional driving output corresponded to different axle heights. As a whole, the thrust and the moment decreased with the increase of navigation velocity and increased with the increase of rotation velocity, and the changing trend of the lifting force was different.

Abstract:In order to deeply study the failure mechanism of sealed relay contact, it is necessary to investigate the correlation analysis between corrosion topography and type. The contact DEAX SEM diagram of sealed relay was selected as the analysis sample. Based on the analysis of possible types of corrosion reaction, it extracted irregular contours on the extraction distribution of corresponding elements, thereby eliminating the non-corrosive part and restoring the 3D shape of the corrosion area. The eigenvalues of the corrosion morphology were analyzed quantitatively and matched the possible corrosion type. Finally, BP neural network algorithm was used to verify the relevance. The results showed that the percentage of Ag and Cl atoms in the contact of sealed relay was approximately 1:1, so it was highly possible to produce AgCl compounds in certain areas. At the same time, the mapping relationship between contact topography and corrosion type was determined. It is concluded that the corrosion topography characteristics of each reaction still exist under the combined action of various corrosion reactions, and this paper provides a method to explore the relationship between corrosion types and corrosion morphology characteristics.

Abstract:To solve the problem of long training time and over-fitting of small sample EEG signal processing, this paper proposes a DBN based on random retreat algorithm, which can classify and identify the left and right hand motion imaginary EEG signals. Firstly, the original EEG data were processed by dimension reduction, and the random DBN model was used to train the reduced EEG data, then the optimal parameter values for classification and recognition were obtained. The experimental results show that compared with CSP, PCA and single DBN network, the DBN algorithm based on random retreat can maintain the high recognition rate and reduces the training time, which proves the effectiveness of the method. Finally, the feasibility of the algorithm was verified on the intelligent wheelchair platform.

Abstract:The wide-range change of inertia on the motor shaft in permanent magnet synchronous motor (PMSM) elevator door system results in difficulties in PI controller parameters design. This paper presents an improved linear active disturbance rejection control (LADRC) strategy for PMSM to solve this problem. ADRC was designed to observe and compensate the disturbance caused by rotational inertia and changing load, to improve the control performance, and to avoid the real-time parameter calibration process of controller. The parallel linear extended state observers (LESO) were proposed to improve LADRC's tracking precision and anti-disturbance ability under the condition of limited bandwidth value, while maintain the simple parameter tuning characteristic at the same time. Both simulation and engineering verification showed that the proposed improved automatic disturbance rejection control system achieved better control performance and simplified the calibration process of the controller parameters. The system also has wide applicability to different types of door machine systems. The improved control system can reduce application cost and improve its industrial competitiveness.