in a novel dual bed reactor fischer-tropsch synthesis was studied by using two diffrent cobalt catalysts. an alkali-promoted cobalt catalyst was used in the first bed of a fixed-bed reactor followed by a rutenuim promoted cobalt catalyst in the second bed. the activity, product selectivity and accelerated deactivation of the system were assessed and compared with a conventional single bed react...

Flow hindrance by salt-marsh vegetation is manifested in the structure of the tidal current; it has a significant impact on sediment transport and causes increased sediment accretion. The flow characteristics in 3 different vegetation types (Spartina maritima, Sp. anglica and Salicornia/Suaeda maritima) were measured on 3 salt-marshes in Portugal and England. Skimming flow develops above the Sp...

Water flow affects settlement of marine larvae on several scales. At the smallest scale local flow regime may control the probability of adhesion to the substrate. Our aim was to mechanistically understand the transition from suspended to attached larvae in turbulent flow. Recently it was proposed that opportunities for larval settlement in turbulent boundary layers depend on time windows with ...

................................................................................................................ ii List of Figures ..................................................................................................... viii List of Tables ....................................................................................................... xi CHAPTER 1: INTRODUCTION ...............

This paper presents a mathematical model coupling water flow and sediment transport dynamics that enables calculating the changing surface morphology through time and space. The model is based on the shallow water equations for flow, conservation of sediment concentration, and empirical functions for bed friction, substrate erosion and deposition. The sediment transport model is a non-capacity ...

The injection of gas in a liquid-saturated granular bed gives rise to a wide variety of invasion patterns. Many studies have focused on constrained porous media, in which the grains are fixed in the bed and only the interstitial fluid flows when the gas invades the system. With a free upper boundary, however, the grains can be entrained by the ascending gas or fluid motion, and the competition ...

channel flows have three components of velocity, 1component in flow direction and 2components in spanwise of channel. because of heterogeneity of velocity undulations, in the channel section the vortices are formed that are nominated “secondary current cells”. these cells cause the lateral shear stress in the channel walls and introduce the erosion and scour of the channel walls. heterogeneity ...

This manuscript presents a novel formulation for linear elastic model of heterogeneous arterial section undergoing uniform pressure in quasi-static regime. The novelties are twofold. First, an bed support on the external boundary (elastic condition) replaces classical Dirichlet condition (i.e., blocking displacements at arbitrarily selected nodes) solids to ensure solvable problem. In addition,...