Abstract:To understand the performance of high strength weathering steel (HSWS) and its technical application in bridge engineering, this paper first summarizes the research progress and achievement of weathering steel (WS) applied to bridge engineering at home and abroad, and reviews the development history of the WS technology. Then, the corrosion mechanism, corrosive environment, and corrosion resistance of HSWS, as well as the corrosion evaluation methods are analyzed. Moreover, the weld performance of HSWS, and the corrosion-fatigue (C-F) performance and evaluation methods of WS are summarized. Finally, the application of HSWS to bridge engineering and the test situations of Chinese HSWS are elaborated. Analysis result indicates that although the technology of Chinese WS has achieved great improvement, the technology of Chinese WS bridges is still in an embryonic stage. Study on strength, stabilization, and fatigue of WS bridges under corrosion effect will be the future research orientation. The fatigue strength of WS bridges can be promoted by utilizing new weld technology to critical part. The fatigue and mechanics performance of Chinese HSWS can meet the requirement of bridge construction, and those of corroded HSWS are worth in-depth study. In addition, C-F model based on electrochemistry corrosion and fracture mechanics can be utilized to evaluate the C-F life of HSWS.

Abstract:To predict residents’ preference for travel modes more precisely, a comprehensive conversion cost model considering psychological factors is introduced in this paper. By taking the travel behaviors of Hangzhou residents as an example, online and offline surveys using questionnaire were conducted with the aid of the contingent valuation method to obtain travelers’ personal information, choice for travel mode chain, and the maximum cost quantified by the expense that they are willing to pay for avoiding mode conversion. Results show that the variable conversion cost increased with the increase of conversion series and had a positive exponential correlation with conversion time. Meanwhile, the results demarcated fixed conversion cost matrix among all the modes in different conversion series. The establishment of the comprehensive conversion cost calculation model can predict the travel demands of residents based on the travel mode chain.

Abstract:In order to study the thermal deflection of cable-stayed bridges and obtain the response components of signals, the Nanjing No.3 Yangtze River Bridge was taken as the research object to analyze the multiple time scale characteristics of long-term deflection monitoring signals. The deflection signal was reconstructed on two time scales (diurnal and annual) by using wavelet multi-scale analysis method to realize separation of thermal deflection. The characteristics of diurnal thermal deflection under solar radiation were studied based on long-term monitoring data. Results show that the diurnal thermal deflection had seasonal differences in annual cycle, and it lagged behind the solar radiation in diurnal cycle. There was a strong positive correlation between the diurnal thermal deflection and the solar radiation excluding the lag effect. Considering the influence of season, ambient temperature, and solar radiation, a multi-fold line model of diurnal thermal deflection with prediction error less than 2 cm was proposed, which could predict diurnal thermal deflection at any time in diurnal cycle.

Abstract:To investigate the shear performance, bonding performance, and low temperature performance of the composite waterproof cohesive layer of cement concrete bridge deck, the Jianhua Bridge on Beian-Fuyu highway was taken as the research object. Composite specimens were prepared using cement concrete, SBS modified asphalt waterproof cohesive layer, and AC-5 asphalt sand, and the amount of waterproof cohesive layer was taken as a variable to carry out direct shear and pull-out tests. Meanwhile, asphalt sand AC-5 beam specimens were prepared to conduct low temperature cracking and low temperature shrinkage tests. Results show that when the amount of waterproof cohesive layer was 0.6 kg/m², the interlayer shear strength was the best, reached 3.45 MPa. With the increase of the amount of waterproof cohesive layer, the pull-out strength first increased and then decreased. When the amount of waterproof cohesive layer was 0.8 kg/m², the pull-out strength was the highest. The maximum bending strain at the bottom of asphalt sand beams decreased with the decrease of temperature, while the flexural stiffness modulus was gradually increased, and the bituminous mixture had the severest deformation in the temperature range of -5--10 ℃.

Abstract:In order to evaluate the risk in the process of natural driving, Bayesian network was used to carry out quantitative research on driving risk. First, natural driving test was conducted to obtain the vehicle control data of vehicle spacing, acceleration, and steering entropy, as well as the eye movement data, including the driver’s sight transfer time, saccade speed, and blink frequency. Then, the risk rule of each index data was analyzed, and the risk level threshold of each index was determined. Finally, a vehicle operation risk assessment model based on Bayesian network was constructed, and the risk quantification classification method was proposed. The risk level of vehicle operation was determined, and the sensitivity of the model was analyzed. Results show that the Bayesian network model based on vehicle control and eye movement characterization could effectively conduct quantitative evaluation of driving risk in the driving process. The research results can provide theoretical and technical support for driving risk assessment and early warning in the natural driving process.

Abstract:To study the structure of asphalt concrete and enrich the characterization of asphalt concrete structure parameters, common volume parameters were summarized to analyze the composition and structural characteristics ofz asphalt concrete. Then, new volume parameters were constructed from different angles, and the parameters were classified and analyzed. Finally, within the scope of the AC-16 grading, five different gradations were obtained by changing the proportion of fine aggregate. Meanwhile, three different dosages of asphalt: 4.2%, 4.7%, and 5.2% (the percentage of asphalt by mass in asphalt mixture) were set to investigate the influence of asphalt content on parameters. Standard Marshall specimens were made according to the existing asphalt mixture production test code requirements, and the volume index was determined. The constructed parameters were obtained by calculation, and the variation of the parameters with gradation and asphalt content was analyzed. Results show that the volume parameters changed obviously with the gradation of asphalt mixture and the change of asphalt content. The asphalt parameters VA, VM, and d_b had obvious linear relationship with the amount of asphalt in the mixture, and VM was related to V_f. The void parameters VMA, V_K, and VV decreased first and then increased with the increase of V_f. When only changed the asphalt content, parameters VMA, V_K, and VV decreased with the increase of the asphalt content. The aggregate parameters G, V_c, V_f, Vf /(1-c), F_BV, F₁, F₂, and V_c/fwere related to the proportion of coarse and fine aggregate and mineral powder in the mixture.

Abstract:To further understand the impact factor (IF) of bridges under moving vehicular loads, key problems such as the basic concept of IF, IF for different responses and positions were discussed in detail by combining theoretical derivation and numerical simulation and considering the physical significance of IF. Results show that the IF in the current specification was only a median parameter for convenient design, which had no actual physical meanings. IFs of different responses were not the same, and IF of moment was smaller than that of deflection in most cases. Moreover, IF in various sections were different, where the IF of pier-top section was the largest, followed by that of abutment span, and then that of center span. For two sections located symmetrically, the IF of the latter section in the direction of moving vehicles was bigger. Due to different principles, a more conservative value of IF can be used for design, but it cannot be directly utilized in evaluation. In the end, recommendations of IF for design and evaluation of dynamic performance of bridges subjected to moving vehicular loads were proposed, respectively.

Abstract:It is a big problem to reasonably formulate the control standard for settlements of pavement caused by tunnel construction. To address this problem, this study proposed a complete solution based on strict theoretical deduction, which took the driving comfort control standard as the starting point, and considered both the roughness of existing highway and the morphological characteristics of pavement settlement trough caused by tunnel construction. First, the vertical vibration acceleration was selected as the comfort index. Second, the ideal sinusoidal function was used to depict the longitudinal curve of highway pavement, and the relationship between the characteristic parameters of the existing highway longitudinal curve and the vertical vibration acceleration was revealed by derivation. Third, the Peck formula was applied to describe the morphological characteristics of pavement settlement trough induced by tunneling, and the relationship between the morphological characteristic parameters and the vertical vibration acceleration was obtained by derivation. Fourth, the formula for calculating the maximum vertical vibration acceleration was established by incorporating the overlapping effect of the existing highway roughness and the pavement settlement induced by tunneling. Finally, based on the relationship between the acceleration value and the subjective feeling of human body, the formula for determining the control standard of pavement settlement was proposed. Results show that the driving comfort was directly proportional to the wave length of the existing highway longitudinal curve and inversely proportional to its amplitude; the driving comfort was directly proportional to the width coefficient of the settlement trough and inversely proportional to the maximum settlement value of the pavement at the tunnel center line; and the driving comfort was inversely proportional to the square of the driving speed. Therefore, an effective way to relax the settlement control standard is to reduce the driving speed properly.

Abstract:The critical flutter wind speed of bridges is a random variable due to the characteristics of the bridge structure and the uncertainties of the external environment (such as stiffness, mass, damping ratio, and aerodynamic derivative), which makes it difficult to investigate the flutter stability of bridges. In this study, by taking the Jiangyin Yangtze River Bridge as an example, the probability density evolution method was combined with the bridge flutter multi-modal coupling analysis method to analyze the probability density evolution process of different modal damping ratios and frequencies considering the uncertainties of the bridge structure and the aerodynamic derivative. The research show that the probability density distribution of the damping ratio and frequency obeyed normal or lognormal distribution at low wind speed, while that at high wind speed could not be described by a single probability distribution since conditions of bimodal or even multi-peak would occur. Compared with the traditional deterministic method, the critical flutter wind speed obtained by the proposed probability density evolution method was smaller.

Abstract:To simplify the process of selecting ground motion intensity measures and further reduce the variability of probability seismic demand models without significantly increasing computational cost, a vector-valued intensity measure selection model for specific site conditions and structure types was established. First, based on 20 scalar-valued intensity measures (IMs) candidates, the variance inflation factor method was used to eliminate the unimportant IM which can be linearly represented by other IMs, thereby eliminating the collinearity among IMs. Then, non-collinearity IMs which have significant correlation with engineering demand parameters were picked out as components of vector-valued intensity measure based on partial determination coefficient. Meanwhile, a three-span prestressed concrete continuous girder bridge, located on the east Nanhuan Road of Handan city, was taken as an example to verify the validity of the proposed method. Results of 6-fold cross-validation show that the variability of the regression model established by vector-valued IM [S_a(0.2),S_a(1.0),T_m] on training dataset and test dataset was reduced by 13.67% and 17.07% respectively, compared with the regression model established by scalar-valued IM[S_a(1.0)], and no overfitting phenomenon was observed. The research results can be utilized to select appropriate vector-valued intensity measures for continuous girder bridges under specific site conditions.

Abstract:To solve the problem of fixed local rule control precision caused by frequent traffic flow phase transition and complex road network topology in self-organizing control of urban traffic signals, this paper proposes a reconstruction method of urban traffic signal self-organizing control rule neighborhood. First, neighborhood was defined as the associated adjacent intersections combination which is constructed by the current intersection with its self-organizing control rules. Next, based on the set of the adjacent intersections of the current intersection, with the combination of the methods such as factor analysis and cross-correlation, the relative spatial expression of location as well as the relative temporal expression of traffic flow transmission between current intersection and any adjacent intersection was constructed so as to realize the time-space quantitative expression between the current intersection and all of its adjacent intersections. In the end, the signal switching rules for the current intersection were established based on the fluid dynamic equation. With the established quantitative relationship, the self-organizing control rule neighborhood of the current intersection was reconstructed in its associated adjacent intersection set. Simulation results show that the maximum capacity and the overall capacity of the current intersection increased with the expansion of the neighborhood. Neighborhood reconstruction can solve the problem of control precision caused by fixed rule neighborhood, and the expansion of the neighborhood can affect the stability of traffic flow release.

Abstract:To improve the stress and deformation of long span CFST arch bridge during concrete pouring, a self-regulating loading pouring method was proposed based on the stress and deformation influence line of arch rib. The theoretical formulas between weighted bending moment energy and concrete age of arch ring were deduced, and a method of optimizing perfusion interval was introduced to minimize the difference of weighted bending moment energy between staged and primary bridge constructions, which can avoid early bearing of filled concrete. A perfusion simulation program for New Longmen bridge was developed using the APDL of ANSYS, and the optimization analysis of segmental pouring for CFST arch bridge was performed. Results show that the proposed self-regulating loading pouring method could be applied to CFST arch bridge, and the self-control of deformation and stress during construction could be realized with the pouring scheme based on the stress and deformation influence line. The optimization method aiming at minimizing the difference of the weighted bending moment energy between staged and primary bridge constructions could reasonably determine the staged perfusion time for long span CFST arch bridge. Comparing with the methods such as temporary cable and water tank, the self-regulating loading pouring method could reduce auxiliary process and decrease the total cost of the construction.

Abstract:To continuously test the bearing capacity of pavement structure under actual traffic loads, the continuous impact load of a vibration equipment with vibrating drum jumping on a pavement structure was used to simulate actual vehicle loads, and a dynamic model of “machine-ground” system was established considering the vibration mass of pavement structure and the change of initial phase angle in each movement stage. Then, a multi-layer elastic system of the pavement structure was equivalent to an elastic half-space body which uses the composite modulus of multi-layer structure to represent the bearing capacity of the pavement structure. By comparing and analyzing the mean and root-mean-square values of the negative acceleration extreme value of the vibrating drum in different statistical durations, the mean value in the statistical duration of 4 s was proposed as the index for evaluating the acceleration signal of the vibration drum. The regression relation between the acceleration signal of the vibration drum and the composite modulus of the pavement structure was obtained when different types of vibration device continuously impacted the pavement structure with different bearing capacities, and the feasibility of the method was proved by field test. Research results show that there was a good regression relationship between the acceleration signal of vibration drum and the composite modulus of road structure under jumping condition. With the changes of the pavement structural composite modulus, the smaller the mass of the vibration equipment was, the more obvious the change of the acceleration signal index of the vibration drum was, and the better the detection effect was. Therefore, a vibration equipment with the weight of 2 t and excitation force of 100 kN could be used to continuously test the bearing capacity of pavement structure under actual traffic loads.

Abstract:This paper aims to determine the corrosion expansive pressure and its change rule, study the process of concrete cover cracking under corrosion expansive pressure, and improve the service life of concrete structure. Considering the concrete strain softening and concrete damage, finite element simulation and analysis of the process of concrete cracking caused by rebar corrosion and the distribution and variation of corrosion expansive pressure were carried out by changing the parameters such as cover thickness, diameter of steel bar, and concrete strength. Results show that the expansive pressure of uniform corroded steel bar was nonuniform, which was influenced by crack. The expansive pressure reached its peak before the crack penetrated the cover, then it decreased quickly, and finally remained stable. The influence of cover thickness c and bar diameter d on expansive pressure was linear, and parameters c and d could be described with a unified c/d value. Furthermore, the larger the c/d value was, the larger the expansive pressure and corrosion rate were, which means the concrete cover cracking was delayed. Finally, a simplified formula was proposed to estimate the maximum expansive pressure, and the validity and precision of the formula were validated by experimental data.

Abstract:To improve the performance of garbage cleaning, a dust collector was designed based on the tornado principle and its structure parameters and extended domain were analyzed. The flow field of the dust collector was calculated using finite volume method, RNG k-ε model, and ANSYS FLUENT 16.0, and the influences of each structure parameter and extended domain parameters on the formation and dust suction effect of tornado were analyzed. The principle and the design scheme of the new type of dust collector were proposed. Results show that the upper part of the tornado was completely developed and the structure was stable, when the ratio of the height of the dust outlet to the diameter of the nozzle was 1.6. The tornado produced by the device had a distinct single vortex structure, and the wind speed near the surface of the nozzle was the largest and the dust suction effect was the best, when the ratio of the height between the nozzle inlet and the ground to the diameter of the cylinder was 0.2. When the inclination angle of diversion orifice was 45° or -45°, the structure of the tornado generated by the device was the most stable and the intensity was the largest. With the increase of the swirl ratio in a certain range, the intensity of the wind field structure in the proposed device was increased, which was beneficial to the improvement of dust collection efficiency. Moreover, the height and the diameter of the extended domain had threshold values, and when the extended domain parameter was greater than the corresponding threshold, its impact was negligible. By setting appropriate structure parameters, the proposed dust collector can form a tornado-like flow field with strong stability and good dust suction effect, and can achieve an efficient cleaning effect.

Abstract:Aiming at the problem that the existing evaluation methods of water seepage and accumulation of bridge deck pavement waterproof interlayer are not perfect, digital image processing technique was used to quantify the pore distribution of interlayer, and the evaluation method of water seepage and accumulation was proposed based on indexes of porosity, pore number, and equivalent pore diameter. Then, a three-dimensional reconstruction model of pores in bridge waterproof interlayers was established and the structure of the pores was visually presented. At last, combining with the transverse permeation tests of 5 typical interlayers, the reliability of the digital image analysis technique in evaluating water seepage and accumulation of interlayers was verified. Test results show that synchronous surface dressing had rich pore distribution and large pore size, which is easy to permeate water and can supply sufficient space for water accumulation. The pores of AC-5 and slurry seals were dense and small, making the seepage resistance of AC-5 better than that of synchronous surface dressing. The porosity of the SBS modified emulsified asphalt as interlayer was small, and there was little connectivity between pores due to the dispersion of pores. Therefore, the waterproof performance of SBS modified emulsified asphalt used as bridge waterproof interlayer was the best.

Abstract:To solve the problems such as lack of advance guide signs of small spacing segment exits on urban expressway, this study proposed five kinds of advance sign setting schemes and conducted a driving simulation experiment. Nine types of evaluation indicators were extracted and analyzed by repeated ANOVA, and six indicators were selected which were significantly affected by different schemes. TOPSIS method combined with entropy weight coefficient was used to evaluate the effectiveness of the five schemes. Results showed that it had the best effect on the driving behavior when setting advance guide signs at 1 km, 0.5 km, and 0 km before the starting point of the deceleration lane. It was followed by the scheme with four advance guide signs according to China standard (GB 5768.2—2009), and the scheme with four advance guide signs according to Japan related standards. K-means cluster and LSD comparison analysis revealed that the effectiveness of setting one advance guide sign was poor. Since the scheme of three advance guide signs had the best effectiveness, it is recommended to be adopted. When road conditions are limited, at least two advance guide signs should be set.

Abstract:To measure the impact load of moving vehicles on bridge expansion joint and avoid the early damage of bridge expansion joint under such impact, models of vehicle and bridge were constructed with a scale of 1/30, and the experimental study of the model vehicle passing through the model bridge was carried out. Considering the change of the contact length between the tire and the road when the wheel passes through the bridge expansion joint, two improved calculation methods for the impact load on the expansion joint were proposed, namely improved calculation method with hypothetical trajectory of tire bottom and improved calculation method based on the distributed spring-damper element. Then the numerical calculation was compared with the experimental results of the scale model. Finally, based on the improved distributed spring-damper element, the numerical simulation and parameter analysis of the impact load induced by three-axle heavy vehicle at single-gap expansion joint were carried out. Results show that compared with the previous method, the impact load of the expansion joint obtained by the improved calculation methods was closer to the measured value. Therefore, it is necessary to consider the change of the contact length between the tire and the road for the calculation of impact load. The maximum impact factor of the wheel load of heavy vehicle exceeded the allowable value of the bridge design specification, which can be controlled within the allowable range by adjusting the opening width of the expansion joint.

Abstract:To investigate metal limit damping device suitable for long-span railway bridges, formulas for calculating the mechanical properties of a metal limit damping device were established, and a simplified design method for the device was proposed. Meanwhile, the device design analysis software was developed with the combination of related design codes and the simplified design method. By taking a typical half-through arch bridge in Zhengzhou-Wanzhou high speed railway in China as the research object, the design parameters of the bridge limit damping device and three connection structural schemes were proposed. The proposed formulas were used to calculate the mechanical properties of the device, the solid finite element model of the device was established, and the influence on the seismic performance of the bridge was analyzed. Results show that the proposed design method of metal limit damping device had strong adaptability and high calculation precision, which met the accuracy requirement of engineering applications. The device could fulfill the driving comfort and safety demands of high speed railway bridges with good effects of seismicity mitigation and energy dissipation, and it reduced the displacement of the beam end for the long-span bridge by about 20%.

Abstract:Aiming at the reentry trajectory reconstruction problem of reusable launch vehicle (RLV), a fast solving method based on variable trust region sequential convex programming (SCP) was proposed. First, the non-convex trajectory optimization problem was convexified by discretization and linearizing the non-convex constraints. Then the convex optimization problem was solved using the SCP method. In the initial iteration of SCP, a predictor corrector algorithm was applied to design the initial guessing trajectory and determine the terminal time. In the subsequent iteration, a variable trust region strategy was proposed based on optimization performance indexes, which improved the convergence performance of the algorithm. On the basis of the fast solving method, considering the unexpected events that may occur during the RLV reentry process, such as large deviation and target point changing, the trajectory was reconstructed online taking the changed initial and terminal conditions into account and was tracked effectively using LQR (Linear quadratic regulator) method. Finally, the designed method was compared with the Gauss pseudospectral method and traditional SCP algorithm. Simulation results show that compared with the pseudo-spectrum method and the traditional SCP method, the variable trust region SCP method greatly improved the real-time and convergence of the trajectory solution, and has the ability to be applied to online trajectory reconstruction. Besides, the proposed online trajectory reconstruction method has good robustness and immunity.

Abstract:In order to study the function and application of partial least squares (PLS) combined with key performance indicators (KPI) in system fault diagnosis, a simulation model was established to simulate wastewater treatment based on the mathematical model of activated sludge (BSM1) and combined with PLS. By collecting the input and output of the system under normal conditions and establishing a relationship matrix, the determination of whether a fault occurs in actual application could be achieved simply by input. Based on the simulation model, the performance of PLS in system fault diagnosis could be verified through changing the conditions of weather, input, and prior knowledge, as well as introducing a multiplication coefficient which can be manually triggered to the simulation system to simulate the fault. Results show that the PLS method had the function of judging the location of the fault, and the sensitivity and accuracy of the function could be improved by combining with KPI. The sensitivity and accuracy of fault diagnosis were affected by the weather factors simulated in the model and the prior knowledge in the algorithm.

Abstract:In Global Navigation Satellite System (GNSS) receiver, the prior information of navigation filter can be used to aid signal acquisition in order to increase acquisition speed and improve sensitivity. By taking the BDS B1I signal as the research object, studies on the estimation of pseudo-random code phase, carrier Doppler, and NH code phase aided by navigation filter in GNSS receiver were carried out. First, the concept of “virtual route” was introduced to derive the computing method of pseudo-random code phase by directly using navigation filter. Then, the error sources and propagation characteristics of pseudo-random code phase and Doppler frequency were analyzed thoroughly. Finally, the theoretical simulation analysis of acquisition performance was conducted. Results show that when estimating pseudo-random code phase and Doppler frequency aided by navigation filter, the acquisition sensitivity was improved by 1.1 dB, and the mean acquisition time was 1 ms. By further aiding the estimation of the NH code phase, the coherent time was extended to 20 ms, the additional acquisition sensitivity improvement of 12.8 dB was achieved, and the corresponding mean acquisition time was 20 ms. The performance of signal acquisition could be improved by utilizing the prior information of navigation filter. Meanwhile, the power consumption caused by frequently running of unaided acquisition engine could be decreased. The algorithms proposed in this paper can be directly applied in GNSS receiver or GNSS/INS deep integration system.

Abstract:To illustrate the electromagnetic scattering characteristics of ultra-high-voltage power transmission line when it is illuminated by high-resolution synthetic aperture radar satellite working at X-band frequencies, the geometric structure and the material properties of ultra-high-voltage power transmission lines were first analyzed, and a physical model was developed for power lines based on the catenary equation. Then, the electromagnetic scattering characteristics of ultra-high-voltage power transmission line at X-band frequencies were analyzed, where the Helmholtz equation in cylindrical coordinates was solved to obtain the two-dimensional diffraction coefficient and, subsequently, the incremental length diffraction coefficient method was employed to acquire the three-dimensional diffraction coefficient and the radar cross section (RCS). Finally, taking into account different polarization modes and diameters of power line, the calculation results of the RCS of power line were compared with the measured anechoic chamber data. Analysis results show that a maximum mean error of 8.1% could be achieved for different diameters of power line, which preliminarily confirms the correctness of the proposed method when it is used for analyzing the electromagnetic scattering characteristics of ultra-high-voltage power transmission line at X-band frequencies.

Abstract:To enhance the efficiency of optimization-based algorithms for detecting community structures in networks, a novel algorithm was designed by utilizing the small-world effects to accelerate biogeography-based optimization process for community detection. First, based on matrix random coding, the problems of detecting community structures in networks were embedded into the framework of biogeography-based optimization. Community structures were searched evolutionarily and globally corresponding to the maximal modularity in habitat. Then, a migration evolutionary strategy was introduced based on the small-world effects, which can accelerate the information exchange process of the proposed evolutionary algorithm. Finally, tests on real-world and computer-generated networks were conducted using the proposed algorithm. Results show that the small-world effects reduced the convergence time of the algorithm for community detection, and the values of the modularity and the normalized mutual information were both high when applying the proposed algorithm to the real-world and the computer-generated networks. The topology structures of information exchanges could optimize the efficiency of the evolutionary algorithm. Therefore, the algorithm adopting small-world effects to accelerate biogeography-based optimization for network community detection was proved feasible and effective.

Abstract:In order to improve the reliability of the motor and the drive system, a mathematical model of stator tooth flux under eccentricity fault was established. Based on the space and time distribution of the tooth fluxes under eccentricity, a fault indicator was proposed which can comprehensively reflect the eccentricity fault and the corresponding parameters. On the basis of real-time tooth fluxes measuring, the extraction method of the fault indicator and the diagnosis method for the eccentricity fault and its type, orientation, and severity were proposed. Simulation and experimental results show that the proposed method can diagnose eccentricity fault accurately and effectively in the full range of operation. It can monitor eccentricity in real-time, effectively reduce the loss caused by the fault, and improve the reliability of permanent magnet synchronous motor and the drive system.

Abstract:In view of the problems existing in the measuring process of thermal conductivity of vacuum insulated panel(VIP), such as long test time and high cost, an embedded heat flow meter method for the thermal conductivity measurement of VIP was proposed. First, the feasibility of the measuring principle was verified by ANSYS, and the measurement systems for the thermal conductivity of VIP were established to obtain the output signal frequency change of VIP with different internal pressures. Then, the quality and service life of VIP was evaluated based on the relationship between output signal frequency change of oscillating circuit caused by temperature change and thermal conductivity. Finally, rigid regression was utilized to improve the extreme learning machine model (RRELM) and the generalization ability of extreme learning machine (ELM). Experiments show that the embedded heat flow meter method could realize the rapid thermal conductivity measurement of VIP. Compared with the traditional ELM, the proposed RRELM model could effectively amend the relationship between the thermal conductivity and output signal frequency change with higher precision.