To study the effect of air humidity on particle filtration performance, the Particle Flow Code (PFC) calculation program was used to numerically simulate the formation process of filter cake. The effects of relative air humidity on the deposition morphology, porosity and filtration resistance characteristics of the filter cake were revealed. The results show that relative humidity (RH) is mainly reflected in the density and surface viscosity of the particles. It was found that the higher the relative humidity, the higher the particle moisture content, the greater the density, and the greater the surface viscosity. With an increase in the particle density or with a decrease in the viscosity, the bridging phenomenon of particle deposition became more obvious; the dendritic deposition phenomenon became weaker; and, therefore, the filter cake structure became denser; the porosity decreased; and the total filtration resistance increased. As the humidity changed, the actual density and viscosity of the particles changed simultaneously with different degrees, which caused different variation trends of the filter cake characteristics. Three different types of particles, DM828 (Starch), PVA1788 (Polyvinyl Alcohol) and Polyacrylamide (Polyacrylic acid), were selected for comparison. For the studied PVA1788 and Polyacrylamide particles, with an increase in relative humidity, the porosity of the filter cake increased monotonously, while the total filtration resistance decreased monotonously. For DM828 particles, the cake porosity first decreased and then increased, and the total filtration resistance first increased and then decreased, with an inflection point at 30% RH. By combining these results with existing reports, three kinds of variations of the filtration performance with humidity could be determined: (1) as the humidity increased, the filtration resistance first increased and then decreased; (2) the filtration resistance decreased; and (3) the filtration resistance increased.

With the development of maritime transportation, oil spill accidents occur frequently. In this paper, a scientific and reasonable assessment of ship oil spills, offshore oil platform oil spills, and subsea pipeline oil spills is carried out, and a risk assessment method of an offshore oil spill based on an n-value neutrosophic set is proposed. First, the oil spill risk evaluation index systems of these three risk sources are constructed, respectively, and the entropy weight method is used to calculate the weight. Second, we establish a risk assessment model under the n-value neutrosophic environment. Furthermore, we use the n-value neutrosophic-weighted arithmetic average (NVNWAA) to calculate the risk levels of the following three risk sources: ship oil spills, offshore oil platform spills, and submarine pipeline spills. Finally, according to the results of the risk assessment, the countermeasures to strengthen the preventive measures of oil spill accidents are put forward.