As an asphalt modifier, diatomite could improve the road performance of asphalt. The adsorption property of diatomite was varied with different compositions of asphalt. The result suggested that diatomite with a developed mesoporous structure could effectively adsorb the lower molecular group and lower polar aromatic molecules, whereas it could not adsorb the asphaltene and resins. In addition, the adsorption amount was related to the curing time. The anchorage was formed after certain molecules in asphalt were adsorbed by diatomite and improved the property of asphalt mastic.

No abstract

The present study considers the results of a structural risk analysis for a 170 000 m 3 vessel with Ice Class IA classification operating from the Baltic Sea to Quebec, Canada. The target vessel is characterized by a Gaz Transport/Technigas (GTT) NO96 containment system for liquified natural gas (LNG) cargo. The capacity of the double-hull structure has been assessed considering inner hull deflection as the critical factor for the safety of the containment system. This capacity is compared with accidental ice load, termed as 'demand' to the LNG carrier, from ice hazards that can occur during Baltic Sea operation in winter or while operating on the Canadian east coast. Risk analysis has been performed to evaluate the risks of the considered ice features in the operation route, based on the study of capacity and demand.

Particle fracture can influence material failure and removal mechanisms in high velocity impact progress. In this paper, a coupled finite element method-smooth particle hydrodynamics numerical model of a single irregularly shaped particle erode metal surface was established to investigate the particle fracture and metal surface erosion. The Johnson–Cook model and Johnson–Holmquist-II model were introduced to describe the deformation of ductile materials and the fracture of brittle materials, respectively. Subsequently, the erosion process of a single irregularly shaped particle impacting different material properties of metal was studied. The results showed the following: (1) The JH-2 constitutive model can simulate the fracture of brittle particles accurately, and the results between simulations and experiments were in reasonable agreement. (2) The extent of particle fracture was lower on softer substrates than on the harder ones. (3) The orientation angle was a key factor affecting secondary impacts of brittle particles. (4) The rigid particle made more damage on the substrate than the brittle one under the same condition.

No abstract

No abstract

No abstract

Nylon cord rubber has the advantages of small residual deformation and is easy to lift and lower the tubing string in low-permeability oil and gas reservoirs. However, it is associated with low-pressure resistance and poor sealing performance. To enhance the performance of nylon cord rubber, a three-dimensional numerical model of the nylon cord rubber was established and its accuracy experimentally determined. The Plackett–Burman test, the Steepest climbing test and the Response surface method were used to acquire the polynomial response surface model connecting structural parameters with bearing and sealing pressure. Using genetic algorithms, optimal structural parameters of nylon cord rubber were determined depending on field operation. The reliability of the optimized results was verified by laboratory tests. It was shown that after optimization, the bearing capacity of the expandable packer increased by 25% while the sealing performance increased by 66%. In addition, the bearing pressure was 70 MPa while the sealing pressure was 50 MPa. These measurements effectively met the on-site requirements of high-pressure and fine fracturing in low-permeability oil and gas reservoirs.