With the improvement of the economic level and the development of automobile technology, the vehicle interior noise control is required to reduce the sound pressure level. In addition, it is necessary to improve the sound quality by adjusting the sound characteristics. In order to meet this goal, many studies have focused on sound quality control objectives, control system modeling, algorithm improvement, algorithmsimulation analysis and experimental verification. Among them, the sound quality active control algorithm is the core of the control system, and it is also the key of research. To further improve the effectiveness, real-time and adaptability of control algorithms, three types sound quality active control algorithms of active noise equalizer (ANE), filtered error least mean square (FELMS), and neural networks were reviewed in detail. The implementation principle, development, advantages and disadvantages of each algorithm were described in detail. At the same time, the existing problems and future development prospects of sound quality active control algorithms were prospected, which could provide a theoretical basis for researchers.

Taking a 6-cylinder, four-stroke, two-stage turbocharged marine diesel engine as the research object, the coupled simulation model of Miller cycle and exhaust gas recirculation (EGR) of two-stage turbocharged diesel engine was established, and the influences of Miller cycle and EGR coupling on the fuel consumption rate and NO_x emissions of the two-stage turbocharged diesel engine were studied. The results show that when the Miller timing is −40°CA, compared with the original engine, the fuel consumption rate is reduced by 3.5%, and the NO_x emissions are reduced by 25.5%. When the EGR rate is 30%, the fuel consumption rate is increased by 5.0% and NO_x emissions are reduced by 98.7%. When the Miller timing is −30°CA and EGR rate is 20%, compared with the original engine, the fuel consumption rate is only increased by 0.1% and NO_x emissions are reduced by 92.7%.

Using the high-frequency fatigue dynamic stiffness test platform and combining with the actual operation conditions of high-speed railway, the stiffness characteristics of Vossloh W300 fastener system under assembly state were studied, and following results were obtained. 1) Under different preloading loads, the static and dynamic stiffness have the same growth trend, and the static stiffness under 20 kN (40 kN) preloading load is 17.7% (59.5%) higher than that without preloading load, the static stiffness corresponding to 40 kN obviously exceeds the design limit of the overall static stiffness of the fastener system. The dynamic stiffness under 20 KN (40 kN) preloading load is 4 dB (10 dB) greater than that under 0 kN. 2) Both the static and dynamic stiffness of the fastener system show low temperature sensitivity. When the temperature is lower than 20 ℃, the static stiffness increases with the decrease of temperature, especially the static stiffness increases sharply from −30 ℃ to −60 ℃, and the static stiffness at −50 ℃ (−60 ℃) is 1.4 (4.4) times that of 20 ℃. The dynamic stiffness at −30 ℃ is 8~10 dB greater than that at 30 ℃, and the elastic unit loses elasticity, which directly affects the vibration reduction effect of the fastener system. 3) The fastener system stiffness has obvious frequency variation characteristics within 5~1000 Hz. When the preload is certain, the dynamic stiffness increases with the increase of frequency, and the dynamic stiffness value at 1000 Hz is 15 dB higher than that at 5 Hz in the national standard.

In the carbon neutral target scenario, a calculation model for total cost of ownership (TCO) of fuel cell vehicles was developed, and the learning curve theory was applied to predict the cost trend of the key components of fuel cell vehicles. The future cost of hydrogen production for the current mainstream technology path was predicted. TCO was used to represent the future cost trend, competitiveness and key influencing factors of China’s fuel cell vehicles.

As a high-precision motion platform, the micro positioning platform driven by the voice coil motor is widely used in precision machining, micro-electromechanical and other fields. Aiming at the high-precision and stable tracking control problem of the micro positioning platform driven by the voice coil motor, combining normalization method with theoretical modeling parameters, a mathematical model of second-order differential equation with parameter uncertainties was established, and the actual displacement of the flexible mechanism was taken as input and the platform control rate was taken as output. In view of the uncertain characteristics of the model parameters, the second-order sliding mode surface of the error was established to propose tracking control of micro positioning platform based on dynamic sliding mode, and the conclusion of system stability through Lyapunov's stability theory was obtained. The proposed control algorithm was analyzed by platform test comparison, the results show that the proposed dynamic sliding mode control algorithm can complete the trajectory tracking with less chatter. The tracking accuracy of the algorithm has improved by 13.4% and 4% compared to traditional sliding mode control, which has a smoother tracking and a good engineering prospects.

The shaft is deformed with the action of load. The misalignment due to deformation caused by the action of load is considered. The fluid-structure interaction method was used. Navier-Stokes equation was solved directly. The three-dimensional transient analysis of shaft and oil film in journal bearing system was carried out. The flow field and solid domain were solved at the same time. Transient film pressure distribution, trajectory of journal center and minimum oil film thickness under different rotate speeds were solved. The results show that the oil film pressure distribution and thickness of oil film change obviously. The minimum oil film thickness decreases, the peak oil film pressure increased when misalignment was considered. The real-time trajectory of journal center, oil film thickness and transient film pressure distribution can be predicted by the transient analysis, which is very significant for the optimal design of journal bearing.

During the process of machine tool precision optimization design, it often regards the error as constant and ignores error distribution in the traditional precision allocation. Based on the analysis of traditional precision allocation method, a precision allocation optimization design of five axis machine tool based on second-order moment error model was proposed to this. The second-order matrix operation rules were defined and the machine tool accuracy index was expressed by the second-order matrix, the error model of five axis machine tool with distribution was established and the multi-objective optimization of the accuracy index was solved by genetic algorithm to obtain the Pareto optimal solution set. Taking C100P five axis machine tool as an example, the feasibility of this optimization design method was verified. Compared with the traditional accuracy allocation method, it can reduce the assembly cost on the premise of ensuring the accuracy requirements of the machine tool.

Accurate acquisition and distortion compensation of point cloud model was the key to 3D laser scanning technology for inspection of parts. A method of obtaining high-precision 3D point cloud model by distortion compensation is proposed. The 3D point cloud model of parts was reconstructed by using a line laser, and the distortion compensation was applied to the included angle error in the model to achieve high-precision point cloud data acquisition. The test platform was established, and the test objects with different materials and structures were selected such as instrument parts, double-layer hole parts and grid components. Through comparative analysis, it has been found that the root-mean-square differences after the distortion compensation were reduced by 0.009, 0.036 and 0.024 mm respectively. The results verified the effectiveness of the distortion compensation method for the point cloud model and its good generality.

To improve the deficiency that the traditional filter-x least mean square (FxLMS) algorithm can not take into account the steady-state error and convergence speed, a variable step size FxLMS (Cosh-FxLMS, ChFxLMS) algorithm based on cosh function was proposed. The relationship between the error signal and the step factor was established by using the cosh function, so that step factor could adjust continuously according to the characteristics of the cosh function. The influence of different parameters on the performance of ChFxLMS algorithm was analyzed to provide guidance for the selection of algorithm parameters. And the sinusoidal signal and measured loom signal were used as input signals to verify the performance of ChFxLMS algorithm. It was compared with FxLMS algorithm and variable step size FxLMS algorithm based on sigmoid function (Sigmoid-FXLMS, SFFxLMS algorithm). The simulation results show that the performance of ChFxLMS algorithm has achieved good control results in time domain and frequency domain. Through comparative analysis, the algorithm can greatly reduce the steady-state error and improve the convergence speed. The research results will provide a new idea for active noise control in workspace.

Aluminum and steel were welded by laser keyhole spot welding technology. The laser keyhole spot welding of Al/steel was tested by orthogonal experiment, influences of time, laser power and defocusing amount on mechanical properties of the joint were studied. The results show that the influence of laser power on the mechanical properties of Al/steel laser keyhole spot welding joints is the greatest, then defocusing amount, welding time affect the minimum. The optimal parameters are laser power 2.85 kW, defocusing amount 22 mm, duration 3 s, and tensile load is 1470 N. The cone-like fusion zone was formed at the weld seam and there was no crack, intermetallic compounds (IMCs) containing Fe₃Al, FeAl and FeAl₂ were formed at the interface. The maximum microhardness (HV) of the joint is 810.

Phospholipase PLA2G1B is closely related to diet-induced obesity and related metabolic disorders. Studies have shown that some natural flavonoid compounds can inhibit phospholipase. An integrated molecular docking and pharmacophore strategy was used to screen PLA2G1B-targeted small molecule inhibitors. Molecular docking of five flavonoid compounds with PLA2G1B were possessed, and their interaction patterns were analyzed. A pharmacophore model based on common ligand molecular characteristics (HipHop) was established, which was used to screen small molecular compounds from ZINC database. The drug-likeness and pharmacokinetic properties (ADME) of the compounds with good fit values were predicted. The results show that kaempferol, luteolin, quercetin, myricetin and epigallocatechin gallate can bind PLA2G1B well, with the binding energies of −7.17~−6.17 kJ/mol. The pharmacophore model consisted of three hydrogen bond donors and one hydrogen bond receptor. By screening 10 897 small molecules in ZINC database, a total of 722 molecules with a hit rate of 6.6% were obtained. The 29 compounds with fit values higher than 2.5 are all meeting Lipinski's rule, and most of the compounds have good ADME parameters. These results can provide reference data for the design of PLA2G1B inhibitors and discovery of lead compounds.

Aggregation-induced emission (AIE)-active materials show important applications in organic photoelectric functional materials. By introducing a phenyl ring, a deplanarization core into the 4-site of naphthalimide chromophore through the typical Suzuki coupling reaction, two new AIE molecules (NIRF2 and NIRF6) based on the common ACQ-active naphthalimide dye were designed and synthesized. Their structures were fine characterized by ¹H & ¹³C NMR and HRMS spectra. The structure-properties relationships were discussed by UV-vis and fluorescent spectra and dynamic laser scattering tests. Finally, both NIRF2 and NIRF6 were successfully applied to image the cytoplasm of the Hela cells. The study results show that the optimized designing strategy can achive the naphthalimide-based AIE-active molecules.

The 2UPR/UPS/UP redundant parallel mechanism (PM) with three degrees of freedom was taken as the research object. According to constraint conditions of this PM, the inverse solution of position and the Jacobian matrix were solved by establishing closed-loop vector equation of each branch. Based on kinematics analysis, the regular pattern of three driving branches was obtained to be convenient to achieve the position and orientation control of this PM. Based on the above conditions, the dynamics of this PM was developed by using the virtual work principle, and the dynamics model was established. Finally, the simulation of mechanism kinematics and dynamics were implemented by applying Matlab and Adams software under typical working conditions. The simulation results can testify the validity of the kinematics and dynamics model. The method lays a theoretical foundation for the design and control of this PM and is fit for the research and analysis of similar mechanisms.

Considering the regional differences of the Yangtze River Delta urban agglomeration, the ecological environment vulnerability assessment differences index system of the Yangtze River Delta urban agglomeration was constructed based on the sustainable development pressure-state-response (PSR) model, and then the maximum relevance and minimum redundancy (mRMR) algorithm, set pair analysis, entropy weight method and so on were comprehensively used. Meanwhile, the vulnerability level of the ecological environment was comprehensively measured and analyzed. The empirical results show that: 1) The index system contains key basic indexes and regional characteristic indexes can reflect the vulnerability of the Yangtze River Delta urban agglomeration. 2) The overall level distribution of the ecological environment vulnerability index of the Yangtze River Delta urban agglomeration is relatively balanced. 3) There are obvious differences in air pollution, population pressure and environmental protection among provinces and cities in the region, among which Shanghai and Hefei have the largest population pressure; Anhui province has the worst air pollution; Environmental protection is the weakest in Jiangsu.

The emergence of virtual fitting system provides consumers with a new shopping experience. To study the relationship between mobile virtual fitting system and purchase behavior, the relationship between sensory experience, perceived service quality, perceived technology and purchase behavior were tested, and a theoretical model with attitude loyalty as mediate variable was constructed. Factor analysis, correlation analysis, regression analysis and process intermediary test were adopted to analyze statistically, and hypothesis were also tested. The results show that sensory experience, perceived service quality and perceived technology have significantly positive effects on purchase behavior. Attitude loyalty plays a mediating role in the relationship between sensory experience, perceived service quality and perceived technology affecting purchase behavior. The research results can provide theoretical reference and practical basis for sensory experience, service quality and technological innovation on mobile virtual fitting system.