Connection between deriving bridges and radial parts from multidimensional Ornstein-Uhlenbeck processes

Summary First we give a construction of bridges derived from a general Markov process using only its transition densities. We give sufficient conditions for their existence and uniqueness (in law). Then we prove that the law of the radial part of the bridge with endpoints zero derived from a special multidimensional Ornstein--Uhlenbeck process equals the law of the bridge with endpoints zero derived from the radial part of the same Ornstein--Uhlenbeck process. We also construct bridges derived from general multidimensional Ornstein--Uhlenbeck processes.     

Gaseous Chloride Complexes with Halogen Bridges—Homo-Complexes and Hetero-Complexes

The chemistry of the gaseous halide complexes which have been observed in large numbers in recent years is discussed for the example of chlorides. Homo-complexes—dimeric or polymeric chloride molecules containing chlorine-bridge linkages [e.g.(NaCl)_n, n = 2—4; (CuCl)_n, n = 2—5; (BeCl₂)_n, n = 2—4; Pd₆Cl₁₂]—occur through broad areas of the Periodic Table. Comparison of the dissociation enthalpy of such molecules with the vaporization enthalpy of the liquid chlorides is particularly informative. Hetero-complexes are formed from different chloride molecules by linkage through Cl bridges. Not only 1:1 complexes (e.g. NaAlCl₄, TIPbCl₃, KThCl₅, CdPbCl₄, AlUCl₈) but also larger molecules (e.g. CoAl₂Cl₈, CrAl₃Cl₁₂, Cu₂UCl₆, In₂UCl₁₀) are known. Types of formulas, structures, and above all the formation enthalpies of such complexes are discussed critically. Hetero-complexes are useful in chemical transport reactions, as aids in syntheses, and in gas-chromatographic separations (lanthanoids, actinoids). They also play a part in many industrial processes (chlorination of ores) and in recently developed types of high-pressure discharge tubes.     

A Mathematical Model of Suspension Bridges

We prove the existence of weak T-periodic solutions for a nonlinear mathematical model associated with suspension bridges. Under further assumptions a regularity result is also given.     

Nonlinear models of suspension bridges

Nonlinear variational equations describing one type of suspension bridges are proposed and studied. The variational equations describe the behaviour of road bed, main cables and cable stays. The road bed is described by two functions connected with vertical and horizontal deformation of any cross section. The main cable is considered to be perfectly flexible and inextensible. The cable stays only resist tensile forces. The variational equations are derived from the principle of minimum potential energy. The existence of solution is based on the Brouwer Fixed Point Theorem. The local uniqueness and continuous dependence on the data represented by gravitational forces acting on the road bed are studied. The local results are based on the Implicit Function Theorem for Banach spaces. A certain stability criterion for suspension bridges is formulated and this criterion indicates how to influence the stability of suspension bridges.     

Aplicación de métodos computacionales en la evaluación de la respuesta aeroelástica de puentes soportados por cables

The possibilities of computational methods for assessing the response of cable supported bridges under wind action are considered in this work. The main objective is to study the possibilities of substituting wind tunnel campaigns by computer based analyses, particularly at the early design stage. The preliminary proposed design for a continuous cable-stayed bridge with two main spans of 650 m and a single box girder deck has been considered as a case study. The force coefficients of the deck cross-section have been computed and the unsteady response associated to vortex-shedding has been simulated using CFD commercial software. Furthermore, an in-house piece of software has been employed to obtain the response for flutter and buffeting phenomena adopting the hybrid approach; with that purpose the experimental flutter functions of a similar box girder deck were adopted. The computational results have been validated by comparison with similar experimental results published by other researchers. It has been verified that the set of adopted methods offers reliable results with moderate costs; therefore, the proposed approach is very suitable at the early design stage of long span bridges or at conceptual design works.