Commercial Case Study on Processing Tahe Medium Gravity Crude

Based on the petroleum processing units of a certain domestic refinery, the authors studied the appropriate cases for processing of Tahe medium gravity crude. The influence of three crude processing cases, including the case for processing of crude slate blended with Tahe medium gravity crude, the case for separate processing and storing of individual crude oils, and the case for flash distillation of Tahe medium gravity crude coupled with separated processing of crude oils, on the products quality, stability of production operation and the overall techno-economic parameters was investigated. The study results have shown that the case for processing crude slate blended with Tahe medium gravity crude could lead to deterioration of the FCC products distribution, dramatic reduction of light distillates, significant surge of sulfur content in FCC naphtha, and increased specific consumption of FCC catalyst, indicating that this case was obviously not suited for processing the Tahe medium gravity crude. The case for separate processing and storing of individual crude oils, however, could increase the aggregate salable products ratio, but the frequent switchover of process streams could cause difficulty and hazards to the stabilization of refining operations, which could not be an ideal processing case. The case for flash distillation of Tahe medium gravity crude coupled with separate processing of crude oils featured the simplicity of process scheme, easiness for modification of process units, easy operation and a slight increase in the aggregate salable products ratio, making itself a suitable case for processing the Tahe medium gravity crude.

Existence and Uniqueness of Positive Solutions for a System of Multi-order Fractional Differential Equations

In this paper, we study a class of ruin problems, in which premiums and claims are dependent. Under the assumption that premium income is a stochastic process, we raise the model that premiums and claims are dependent, give its numerical characteristics and the ruin probability of the individual risk model in the surplus process. In addition, we promote the number of insurance policies to a Poisson process with parameter λ, using martingale methods to obtain the upper bound of the ultimate ruin probability.

Broadband spectral fitting of blazars using XSPEC

The broadband spectral energy distribution（SED） of blazars is generally interpreted as radiation arising from synchrotron and inverse Compton mechanisms. Traditionally,the underlying source parameters responsible for these emission processes,like particle energy density,magnetic field,etc.,are obtained through simple visual reproduction of the observed fluxes. However,this procedure is incapable of providing confidence ranges for the estimated parameters. In this work,we propose an efficient algorithm to perform a statistical fit of the observed broadband spectrum of blazars using different emission models. Moreover,we use the observable quantities as the fit parameters,rather than the direct source parameters which govern the resultant SED. This significantly improves the convergence time and eliminates the uncertainty regarding initial guess parameters. This approach also has an added advantage of identifying the degenerate parameters,which can be removed by including more observable information and/or additional constraints. A computer code developed based on this algorithm is implemented as a user-defined routine in the standard X-ray spectral fitting package,XSPEC. Further,we demonstrate the efficacy of the algorithm by fitting the well sampled SED of blazar 3 C 279 during its gamma ray flare in 2014.