Research on the Recovery of Irregular Flights under Uncertain Conditions

This paper mainly studies the problem of irregular flights recovery under uncertain conditions. Based on the analysis of the uncertain factors affecting the flight, taking the total delay time and the total cost of flight delay as the objective function, and considering the constraints of flight plan and passenger journey, an uncertain objective programming model is constructed. Finally, taking OVS airport temporarily closed due to bad weather as an example, the results show that better quality optimization scheme can be obtained by integrating passenger recovery with narrow sense flight recovery stage and implementing integrated recovery.

Association of Sandstone-Type Uranium Mineralization in the Northern China with Tectonic Movements and Hydrocarbons

In the continental basins of Northern China(NC),a series of energy resources commonly co-exist in the same basin.As the three typical superimposed basins of different genesis in the NC,the Junggar,Ordos,and Songliao basins were chosen as the research objects.The favorable uraniumbearing structures are generally shown as a basin-margin slope or transition belt of uplifts with the development of faults,which are conducive to a fluid circulation system.The Hercynian,Indosinian,and Yanshanian movements resulted in the development of uranium-rich intrusions which acted as the significant uranium sources.The main hydrocarbon source rocks are developed in the Carboniferous,Permian,Jurassic and Cretaceous.The mature stage of source rocks is concentrated in the Jurassic–Cretaceous,followed by the multi-stage expulsion events.Influenced by the India-Eurasian collision and the subduction of the Pacific Plate,the tectonic transformation in the Late Yanshanian and Himalayan periods significantly influenced the sandstone-type uranium mineralization.The hydrocarbon reservoirs are spatially consistent with sandstone-type uranium deposits,while the hydrocarbon expulsion events occur in sequence with sandstone-type uranium mineralization.In the periphery of the faults or the uplifts,both fluids met and formed uranium concentration.The regional tectonic movements motivate the migration of hydrocarbon fluids and uranium mineralization,especially the Himalayan movement.

Characteristics of Altered Ilmenite in Uranium-Bearing Sandstone and Its Relationship with Uranium Minerals in the Northeastern Ordos Basin

In recent years,the close relationship between uranium and Ti-Fe oxides in the sandstonetype uranium deposits has been extensively recognized.However,the altered characteristics of ilmenite and its relationship with uranium enrichment still remain unclear.With this paper based on heavymineral sorting of uranium ore selected from the Tarangaole-Nalinggou deposit in the northeastern Ordos Basin,electron probe,backscattering image,energy spectrum and scanning electron microscopy were systematically performed.The ilmenite in the sandstone can be divided into four groups,including unaltered,weakly altered,moderately altered,and strongly altered ilmenite.The alteration of ilmenite in uranium ores is notably more intense than that of the surrounding rocks.In addition,weakly,moderately,and strongly altered ilmenite associated with uranium minerals in uranium ores demonstrate that the more intensity ilmenite altered,the closer its relationship with uranium minerals is.The ilmenite has likely been somewhat altered before mineralization,and the alteration intensifies by later exposure related to an oxygencontaining fluid.The alteration mechanism comprises a process of competitive diffusion between Fe^(2+)and O_(2)-ions.In the early stage,Fe ions was mainly diffused on the particle surface.Subsequently,diffusion of O ions into the particles began to be dominate.Most of the leached iron is stripped or carried away by fluid.In an alkaline and reductive environment,the remaining iron is reduced to form the surrounding pyrite,and TiO_(2)in a form of titanium sol recrystallizes(i.e.,anatase).Backscattering images show that uranium and altered ilmenite are close in space.Coffinite is often distributed along the edges of altered ilmenite as burrs in shape.Colloidal or knitted coffinite associated with anatase is formed in the voids of altered ilmenite.The chemical composition of altered ilmenite varies considerably from the core to edge,and the mineral assemblage sequence is from girdle with ilmenite,to leucosphenite,to anatase,and to coffinite.There is no brannerite that is symbiotic with altered ilmenite.It is considered to be a uranium-containing titanium mineral aggregate caused by the reduction and adsorption of uranium.As the altered product of ilmenite,TiO_(2)is an aggregation agent,increasing the concentration of uranium by adsorption.Together with Fe^(2+)and S_(2)-in secondary pyrite,this aggregate creates a uranium-rich environment in the microzone for the formation of coffinite.Therefore,the alteration of ilmenite plays a geochemical role in the processes of sedimentary,diagenesis and mineralization,in which Fe is removed,Ti is enriched,and U is adsorbed and reduced.