A dynamic filtration model of the gasoline particulate filter(GPF) was developed，considering both pore and wall scales，with the addition of radial porosity heterogeneity in the porous media. The impact of internal structural changes in the GPF on particle filtration performance was investigated from the perspectives of filtration mechanisms and microscopic size. It is found that the primary filtration mechanisms in the GPF are Brownian diffusion and interception，which correspond to the filtration of small particles(<30nm) and large particles(>200nm)，respectively. When the mean pore size in the GPF decreases or the pore size variance increases，the proportion of collectors with diameters smaller than 10μm increases. This results in a higher number of collectors achieving more than 50% filtration efficiency for particles in the range of 10—300nm，thereby enhancing the total filtration efficiency of the GPF. After 20minutes of particle filtration，the filtration efficiency of GPF increases and the particles adhere to the area of the lowest porosity，where the porosity reduces. However，the efficiency of Brownian diffusion and interception slightly decreases，indicating that porosity plays a dominant role in influencing filtration efficiency during the dynamic filtration process.

The mechanisms of N₂O formation during NO_x reduction over close-coupled selective catalytic reduction(cc-SCR) catalysts for diesel engine exhaust were investigated by small-sample catalysts test combined with numerical simulations. Research results indicate that N₂O is formed at both low(170—300℃) and high(>300℃) temperatures over cc-SCR catalysts. At high temperatures，N₂O is formed as a byproduct through the oxidation of NH₃. However，at low temperatures，the N₂O formation pathway differs from the ammonium nitrate(NH₄NO₃) decomposition pathway observed in conventional SCR systems commonly used in China Ⅵ diesel vehicles. Considering the absence of upstream diesel oxidation catalyst(DOC) for NO oxidation and the inhibitory effect of water vapor(vaporous state) on NH₄NO₃ formation in the cc-SCR system，a low-temperature N₂O formation mechanism via the non-ammonium nitrate pathway was introduced and the single-site kinetic model was utilized during the simulation. The modified reaction mechanisms incorporate temperature-dependent N₂O formation，enabling accurate prediction of N₂O volume fractions at a space velocity of 40000h^-1 across the temperature range of 170℃ to 450℃. Furthermore，the impact of NH₃ coverage on N₂O formation was also studied. Results demonstrate that N₂O formation rates increase with higher NH₃ coverage. Additionally，O₂ enhances N₂O production at elevated NH₃ coverage by promoting NH₃ dehydrogenation.

This study investigated the dominant factors and patterns of change in heat flow variations of diesel engine with respect to altitude and intercooler temperature，with the aim of addressing the issue of efficient thermal management of diesel engine in high-altitude environments. The results indicate that the dominant factors for the heat removed by the intercooler and coolant are temperature differences，while the heat removed by the exhaust is mainly affected by intake/exhaust temperature difference during intercooler temperature changes，and by exhaust mass flow during altitude changes. At a constant altitude，for every 10℃ increase in intercooler temperature，the effective power of the diesel engine，the heat removed by intercooler，and the proportion of miscellaneous heat losses decrease by an average of 0.08%，0.79%，and 0.23%，respectively. Conversely，the proportion of heat removed by the exhaust and the coolant increases by an average of 0.48% and 0.62%，respectively，indicating the more fuel heat is transferred to exhaust and coolant，increasing the cooling load. At a constant intercooler temperature，for every 1000m increase in altitude，the effective power of the diesel engine and the proportion of heat removed by exhaust decrease by an average of 0.44% and 1.37%，respectively. Meanwhile，the proportion of heat removed by intercooler，coolant，and miscellaneous heat losses increases by an average of 0.93%，0.25%，and 0.62%，respectively. This indicates a greater heat transfer toward the intercooler and coolant，suggesting that the intercooler and cooling systems should provide sufficient thermal margin for diesel engine operation at high altitudes.

Thermal conductivity characteristics of the diesel particulate filter(DPF) substrate significantly impact the parking regeneration of diesel engines under plateau conditions. The heat transfer patterns within DPF/catalyzed diesel particulate filter(CDPF) with two substrates with different thermal conductivity characteristics were investigated under steady flow fields，and the effect of thermal conductivity characteristics on bed temperature variations and regeneration efficiency during the parking regeneration was examined. Results show that as the DPF inlet temperature uniformly increases，bed temperatures at all positions rise linearly at faster rates in substrates with higher thermal conductivity. Substrates with higher conductivity exhibit a higher temperature rise rate. During parking regeneration，substrates with higher thermal conductivity exhibit greater regeneration efficiency in DPF and CDPF. Extending regeneration duration gives more regeneration efficiency improvement. Effective active coatings can substantially mitigate the decease in regeneration efficiency caused by substrate thermal conductivity differences in the plateau environments. When the optimized high-conductivity substrate is used with a carbon load of 6g/L and an inlet temperature of 580℃，the CDPF achieves a regeneration efficiency of 95.4% after a 1800s of parking regeneration，meeting the plateau regeneration requirements.

The pulse-jet air-assisted atomization nozzle has the advantages of good atomization characteristics and minimal influence of fuel physical properties on atomization performance，and therefore has good application prospects in ignited aviation heavy fuel engines. In order to investigate the atomization characteristics of multi-fuel used on the pulse-jet air-assisted nozzle，four pure alkanes of n-octane，n-decane，n-dodecane and n-tetradecane were selected to conduct comparative experiments. A phase Doppler particle analyzer(PDPA) technology was used to measure the particle size and axial velocity of spray droplets under the fuel injection pressure of 1.0MPa，the air injection pressure of 0.8MPa and the backpressure equivalent to standard atmospheric pressure. More attention was paid to the processes of the micro-atomization characteristics of different fuel jets from near-field to far-field. It is found that although the atomization performance of the four types of fuel droplets varies due to differences in physical properties，the Sauter mean diameter(SMD) at all sampling points remains below 20µm. With the development of the jets，it exhibits a non-monotonic characteristic of first breaking and then coalescing，and the axial average velocity shows a monotonic increase. Further analysis reveals that the physical mechanism of droplets behind this phenomenon is the interaction between two competitions：Separation-coalescence and coalescence-bouncing-evaporation.

Optimization configuration strategy of sensors in lubrication system monitoring of marine diesel engines offers significant benefits. It facilitates efficient acquisition of operational status data and enables accurate analysis of system characteristics. These improvements deliver reliable data support for maintenance research and engineering applications. A comprehensive evaluation index for optimizing configuration strategy of sensors was constructed based on fault mode recognition，sensor failure tolerance，and sensor quantity. A fault mode correlation matrix was also constructed based on the improved grey relational analysis(IGRA) method，and then the evaluation index was calculated by using rough set theory. A Pareto-optimal sensor configuration was finally achieved by using the non-dominated sorting genetic algorithm Ⅱ(NSGA-Ⅱ). Experimental results demonstrate that the initial configuration with nine sensors monitoring temperature and pressure parameters，including the lubricating oil pump，filters，main engine oil inlet，and oil cooler，can be optimized to that with five sensors while maintaining equivalent fault identification capabilities. The optimized configuration exhibits a robust fault tolerance，sustaining a fault isolation rate from 81.14% to 96.00% during single-sensor failure scenarios.

Fault diagnosis methods for traditional distributed aero piston engines require manual involvement，and the diagnostic process is also discontinuous. Fault diagnosis based on one-dimensional convolutional neural networks(1D-CNN) tends to overfit easily and exhibits a single-scale feature extraction issue. In response to the above issues，a modified residual multi-scale convolution block combined with a convolutional attention mechanism and a multi-scale feature fusion classification layer were designed. Based on this，a residual multi-scale convolutional neural network(RMSCNN) was constructed for fault diagnosis of the ignition and fuel injection systems of an aero piston engine. Initially，multi-scale feature information from raw time-domain data was extracted by improving the residual multi-scale convolution block. Subsequently，the network structure with parallel outputs was dimensionally reduced and fused to form a multi-scale feature fusion layer. Finally，Softmax was used for classification recognition. Experimental results show that for a dataset of 16 fault categories of the aero piston engine，including abnormal ignition advance angle and abnormal fuel injection quantity，RMSCNN achieves a fault diagnosis accuracy of 91.44%. Compared to common networks such as 1D-CNN，GoogLeNet，and ResNet50，it demonstrates superior fault diagnosis performance.

The extensive emission of carbon dioxide，leading to global warming，has attracted widespread attention. Excessive energy consumption for regeneration has become the main reason limiting the application of carbon capture systems(CCS) on ships. In this study，tailored to the specific needs of marine diesel engines，a novel two-phase absorption system，3-methylaminopropylamine-sulfolane-water(MAPA-SFL-H₂O) was constructed. Experiments were conducted using simulated ship exhaust with a gas flow rate of 1000mL/min. The absorption，desorption，and cycling performance of the two-phase absorbent were investigated under various conditions，including different absorbent composition ratios，absorption temperatures(30—60℃)，CO₂ volume fraction(3%—5%)，and impurity gases(SO₂ and NO)，using a bubbling device and titration setup. The results indicate that the absorption rate of the MAPA-SFL-H₂O two-phase absorbent under the different CO₂ volume fraction conditions of ship exhaust is higher than that of monoethanolamine(MEA). When the mass ratio of the absorbents is 3: 3:4，the system exhibites its optimal performance. Compared to MEA of equal mass，the cyclic load is increased by 72.3%，while the energy consumption for regeneration is reduced by 28.4 %. Carbon-13 nuclear magnetic resonance(¹³CNMR) detection results show that the primary amine groups in MAPA are the main CO₂ carrier，and the secondary amine groups are involved in proton transfer. The phase change of the absorbent is influenced by the CO₂ load. An increase in CO₂ load promotes the precipitation of SFL to form a lean phase，which facilitates two-phase separation and significantly reduces the energy consumption for regeneration.

In order to investigate the abnormal collision fault of piecewise stiffness spring-damper coupling in the transmission system of a diesel generator set during the startup，a dynamic model of the transmission system considering coupling collision was established. Based on the model，the fault mechanism and diagnosis method were studied，and the scheme to eliminate the fault was proposed. First，the frequency characteristics of measured torsional vibration signals of the transmission system during the startup of the unit were analyzed. Combined with the torsional vibration modal characteristics calculated by the free vibration of the transmission system，it was confirmed that the collision occured between the driving and driven ends of the coupling when the unit passes the critical speed during the startup. Next，the stress of the key part(intermediate plate) of the coupling during the collision between the driving end and the driven end of the coupling was further studied. It is found that the maximum stress of the intermediate plate of the coupling reaches 325MPa，which exceeds the fatigue limit of 225MPa for the intermediate plate material，resulting in the fracture of the intermediate plate of the coupling. Then，a dynamic model of the transmission system considering coupling collision was established，the mechanism of abnormal coupling collision fault during the startup of the diesel generator set was studied，and the influencing factors such as stiffness and damping were analyzed. Finally，a scheme of replacing the original coupling was proposed and verified by experiments，and the problem of abnormal collision fault of coupling was solved.