Abstract:
We used ultraviolet spectra from HST/STIS (R=30,000), together with optical spectra from Keck/HIRES (R=45,000), to study the three MgII-selected absorption systems at z=0.9254, 0.9276, and 0.9342 toward the quasar PG 1206+459. A multi-phase gaseous structure, with low-ionization components produced in small condensations and high-ionization ones in diffuse clouds, is indicated in all three systems. Each system is likely to represent a different galaxy with absorption due to some combination of interstellar medium, coronal gas, halo gas, and high-velocity clouds. Even with the improved sensitivity of HST/COS, we will only be able to obtain high-resolution ultraviolet spectra of the brightest quasars in the sky. A larger telescope with ultraviolet coverage will enable quasar absorption line studies of hundreds of galaxies, including a wide range of galaxy types and environments at low and intermediate redshifts.

Abstract:
Fine particles play an important role in the atmosphere. Research on heterogeneous reactions on the surface of fine particles is one of the frontier areas of atmospheric science. In this paper, physical and chemical characteristics of fine particles in the atmosphere and the interactions between trace gases and fine particles are described, methods used in heterogeneous reactions research are discussed in detail, progress in the study of heterogeneous reactions on the surface of fine particles in the atmosphere is summarized, existing important questions are pointed out and future research directions are suggested.

Abstract:
We prove a multiplication theorem of a quantum Caldero-Chapoton map associated to valued quivers which extends the results in \cite{DX}\cite{D}. As an application, when $Q$ is a valued quiver of finite type or rank 2, we obtain that the algebra $\mathcal{AH}_{|k|}(Q)$ generated by all cluster characters (see Definition \ref{def}) is exactly the quantum cluster algebra $\mathcal{EH}_{|k|}(Q)$ and various bases of the quantum cluster algebras of rank 2 can naturally be deduced.

Abstract:
In order to avoid the state space explosion problem encountered in the quantitative analysis of large scale PEPA models, a fluid approximation approach has recently been proposed, which results in a set of ordinary differential equations (ODEs) to approximate the underlying continuous time Markov chain (CTMC). This paper presents a mapping semantics from PEPA to ODEs based on a numerical representation scheme, which extends the class of PEPA models that can be subjected to fluid approximation. Furthermore, we have established the fundamental characteristics of the derived ODEs, such as the existence, uniqueness, boundedness and nonnegativeness of the solution. The convergence of the solution as time tends to infinity for several classes of PEPA models, has been proved under some mild conditions. For general PEPA models, the convergence is proved under a particular condition, which has been revealed to relate to some famous constants of Markov chains such as the spectral gap and the Log-Sobolev constant. This thesis has established the consistency between the fluid approximation and the underlying CTMCs for PEPA, i.e. the limit of the solution is consistent with the equilibrium probability distribution corresponding to a family of underlying density dependent CTMCs.

Abstract:
The syntactic nature and compositionality characteristic of stochastic process algebras make models to be easily understood by human beings, but not convenient for machines as well as people to directly carry out mathematical analysis and stochastic simulation. This paper presents a numerical representation schema for the stochastic process algebra PEPA, which can provide a platform to directly and conveniently employ a variety of computational approaches to both qualitatively and quantitatively analyse the models. Moreover, these approaches developed on the basis of the schema are demonstrated and discussed. In particular, algorithms for automatically deriving the schema from a general PEPA model and simulating the model based on the derived schema to derive performance measures are presented.

Abstract:
A novel organic polymeric flocculant was synthesized by grafting cationic etherifying monomer (3-chloro-2-hydroxypropyl) trimethyl ammonium chloride (CHPTAC) onto the backbone of corncob powder (CP,F≤ 30mm). The synthetic reaction between CP and CHPTAC was initiated by hydroxyl radical made from Fenton reagent(H_{2}O_{2}-FeSO_{4}). The alkalization process andsynthetic reaction conditions were optimized byva- rying several parameters affecting grafting efficiency, such as NaOH dose, monomer concentration, reaction temperature and time and distilled water dose. The synthesized cationicflocculant was characterized by elemental analysis,Fourier-transform infrared spectrometer andscanning electron microscope techniques. Itwas concluded that the backbone of CP have been grafted cationic etherifying monomer. The flocculation characteristics in 0.25% (w/v) kaolin suspensions was compared with some of thecommercial flocculants available in markets,and the results demonstrated the synthesized cationic flocculation has superiority as a novel flocculant.

Abstract:
Parallel and orthogonal tests are used to explore the influence law of the dosage and age of curing agent on the strength of solidified sludge. The test results show that: 1) The strength of solidified sludge is mainly related to the cement content and dry soil content, and presents a good linear relationship. The influence of gypsum content is not significant. As the age increases, the strength is greatly affected by the cement content. 2) At different ages, the unconfined compression strength of solidified sludge presents a linear relationship, and the change law of later strength can be predicted by early strength. 3) Degree of influence of curing agent dosage: cement dosage > gypsum dosage > dry soil dosage. The optimal mixture ratio is 8% of cement content, 30% of gypsum content (proportion of cement content), and 4 times of dry soil content (multiple of cement content).

Abstract:
Let ？ be a family of meromorphic functions defined in , let (？？？0), 0,1,...,？1 be holomorphic functions in , and let be a positive integer. Suppose that, for every function ∈？, ≠0, ()=()

Abstract:
The Sharma-Tasso-Olver (STO) equation is investigated. The Painlevé analysis is efficiently used for analytic study of this equation. The Bäcklund transformations and some new exact solutions are formally derived.