The fuel consumption meter measurement method and bench test are generally used to analyze the economy and power performance of vehicles, but the two measurement methods have high costs and complex structures. In response to this problem, back propagation (BP) neural network and regression model were selected to calculate and predict the economy and power performance of explosion-proof rubber tire vehicle diesel engines. Through comparison with experiments, the accuracy of BP neural network and regression model prediction was studied. The results show that the error between BP neural network and regression model is less than 5% when predicting fuel consumption rate and evaluating power performance, and both can be used to predict the economy and power performance of rubber tire vehicles.

The paper introduces mechanical character of boom for luffing jib crane, structural form and construction type of the inverted-Y boom are explained. A conversion section is arranged in the middle of the boom, the hoisting or luffing wire rope enters the boom head after bypassing the conversion section, the load of the boom is reduced by the pull of the wire rope. The example of derrick crane with maximum rated lifting capacity of 500 t is given, calculation of the boom shaft pressure, boom dead weight bending moment, wire rope tension and other loads on the boom chord of the magnitude of the axial force exerted, and analyze its proportion. It shows that the effect of hoisting or luffing wire rope can effectively reduce the dead weight bending moment of the boom, and offset part of the boom chord and belly rod axial force, improve the overall stability and bearing capacity of the boom, thus the design of the boom is optimized.

In order to solve the problems of incomplete balance equation, inaccurate balance equation and large error of cam contour caused by the influence of piston deflection on cam dynamic moment in existing cam construction of pedal brake unit, the structure of pedal brake cam and output force stability were studied. Firstly, the concept of optimum compensation angle is introduced, and the rotating moment of the thrust caused by piston deflection in two directions to the cam articulation point is included in the new balance equation, which makes the balance equation more complete, accurate and has less error. Based on this, a new cam mechanism is designed and constructed. Then, on the pedal brake unit routine tester, a comparative experiment is carried out on the stability of output force value between the original cam mechanism and the newly constructed cam mechanism with optimized compensation angle. Finally, the above data and the curves of action travel and output force are comprehensively compared and analyzed. The results show that the output force value stability of cam with compensation angle is better than that of cam without compensation angle. In actual operating stroke, the maximum difference of output force between two times is (-0.8, +0.6) kN with compensation angle cam error, and (-1.2, +1.2) kN without compensation angle cam error. The error with compensation angle cam is also less than that without compensation angle cam error.

Middle outrigger is the main support leg of tunnel erecting machine, and hydraulic system plays an important role in the erection process of prefabricated utility tunnel sections. To solve the problems of slow action and low positioning accuracy of hydraulic cylinder of middle outrigger, the hydraulic system of tunnel erecting machine is optimized through on-site experiments and AMESim simulation analysis. According to the erection process and hydraulic system principle of tunnel erecting machine, a preliminary analysis and on-site measurements of original middle outrigger hydraulic system are conducted, and an optimized system scheme applying high-frequency response proportional valve and accumulator is proposed. Then, the reasonable accumulator working parameters of optimized hydraulic system are explored, and the high-frequency response proportional valve control strategy based on feedforward compensation is studied. Finally, the optimized hydraulic system is simulated and compared with measurement data. The results show that the combination of high-frequency response proportional valve and accumulator can significantly improve the response characteristics and position control accuracy of hydraulic system. The hydraulic cylinder displacement of optimized system is increased by 82.2% within 0.5 s of system startup, and the maximum hoisting positioning error is ±2.0 mm, which can meet the erection and installation requirements of utility tunnels.

To achieve rapid prediction of aerodynamic noise in the rearview mirror area of vehicles, an stochastic noise generation and propagation (SNGR) method is adopted. Unlike general aerodynamic noise simulation methods, this method is based on the reynolds-averaged navier-stokes (RANS) equation to solve the steady flow field, reconstructing the sound source term through a velocity random model, and finally using the finite interpolation method to solve the acoustic analogy equation, greatly reducing the computational period of aerodynamic noise simulation. Based on actual vehicle data, a wind tunnel model is established, with a speed of 120 km/h as the simulation condition. Under the same conditions, the SNGR method and the general unsteady method using large eddy simulation as the flow field calculation model are respectively used for simulation. The results show that the calculation time of the SNGR method is greatly reduced, and the calculation results are consistent in the frequency range of 500-5 000 Hz, proving the efficiency of this method. On this basis, the flow field results in the rearview mirror area are analyzed, and the design of the car rearview mirror is optimized based on the principle of aerodynamic noise generation. Install the rearview mirrors before and after optimization on the entire vehicle for wind tunnel experiments, and verify the accuracy of the SNGR method calculation results by comparing the sound pressure level reduction before and after rearview mirror optimization. The simulation and experimental error of this method is between 4%-5%, proving that this method can be used in the optimization stage of aerodynamic noise performance of vehicle rearview mirrors.