Instability and fragmentation of expanding liquid systems

This analysis pursues the underlying physics governing the expansion, dispersal and breakup of a thin walled steel right circular cylinder filled with liquid after being impacted by a high velocity aluminum sphere. The impact generates a radially expanding coherent thin shell of liquid which stays together to at least a diameter 8 times that of the original cylinder. An instability criterion is proposed and developed based on the opposing forces of stabilizing inertial pressures and destabilizing viscous resistance. This criterion is compared to test data where possible in order to ascertain its ability to predict liquid breakup of the shell. The breakup theory developed here predicts the extensive expansion of the unthickened liquid prior to fragmentation as observed in the experiments. This result lends some credence to the underlying physics pursued here and its ability to predict the onset of liquid fragmentation.     

Strengthening of a Steel Bridge Girder Using CFRP Plates

For bridge owners faced with a rising number of structurally deficient steel bridges, the rehabilitation of steel girders using advanced composite materials offers an attractive solution for short-term retrofit or long-term rehabilitation. Several laboratory studies conducted at the University of Delaware have shown that carbon fiber-reinforced polymer (CFRP) plates can be used to effectively strengthen steel bridge girders. Initial studies focused on several issues including the effect on global stiffness and strength, bond force transfer and development, and environmental and fatigue durability of the CFRP∕steel bond. Once the feasibility of the strengthening procedure had been thoroughly examined, strengthening of an existing steel bridge girder was performed. This paper reviews the research conducted to date, and presents details of a demonstration of this technology performed on a bridge located on Interstate 95 in Newark, Del.     

INFRASTRUCTURE PRODUCTIVITY ESTIMATION AND ITS UNDERLYING ECONOMETRIC SPECIFICATIONS: A SENSITIVITY ANALYSIS

ABSTRACT In recent years researchers have considered a variety of regional models relating to infrastructure productivity. These models are often based upon overly simple econometric specifications and are typically formulated as if spatial interactions are absent. In this paper, we try to account for some of these shortcomings. We do this by considering spatial lags of certain independent variables, as well as of the dependent variable. We also consider spatial correlation of the error terms, general patterns of heteroscedasticity and of time series autocorrelation, and systems problems. Our results strongly suggest that regional infrastructure productivity involves spatial spillovers relating to both observable variables and error terms. They also suggest that corresponding coefficient estimates are very sensitive to model specifications.     

The effect of pulsed reverse current on the polarization behaviour of acid copper plating solutions containing organic additives

The polarization behaviour of acid copper solutions containing polyethers, sulphopropyl sulphides and chloride ions was studied using both direct and pulsed reverse current. The effect of these additives on the rest potentials of copper foils immersed in the electrolyte was also studied. Polyethers were found to have an inhibiting effect on the deposition of copper whereas the sulphopropyl sulphides produced a stimulating (i.e. depolarizing) effect. Chloride ion concentration was found to have an influence on the adsorption characteristics of the polyether. The use of pulsed reverse current in solutions containing both polyether and sulphopropyl sulphide was found to inhibit the adsorption/diffusion of the sulphopropyl sulphide at the cathode surface. Thus at higher current densities, above 2 A dm^–2, the inihibiting effect of the polyether produced a shift in the cathodic polarization potential to more negative values as compared with an equivalent current density using direct current. At lower current densities, below 2 A dm^–2, the depolarization effect of the sulphopropyl sulphide was still effective. This effect of pulsed current on additive containing solutions can improve dramatically the metal distribution in low current density areas on plated items. This was illustrated by plating Hull cell panels using both pulsed and direct current.     

Application of generic risk assessment software to radioactive waste disposal

Monte Carlo methods are used in a variety of applications such as risk assessment, probabilistic safety assessment and reliability analysis. While Monte Carlo methods are simple to use, their application can be laborious. A new microcomputer software package has been developed that substantially reduces the effort required to conduct Monte Carlo analyses. The Sensitivity and Uncertainty Analysis Shell (SUNS) is a software shell in the sense that a wide variety of application models can be incorporated into it. SUNS offers several useful features including a menu-driven environment, a flexible input editor, both Monte Carlo and Latin Hypercube sampling, the ability to perform both repeated trials and parametric studies in a single run, and both statistical and graphical output. SUNS also performs all required file management functions.     

The formation and occurrence of amino acid pyrolysates and related mutagens in cooked foods

The classes of cooked foods that contain detectable levels of mutagenic activity are discussed together with the effects of different cooking procedures on the extent of mutagen formation. Analytical procedures that have so far been devised to quantify the concentrations of specific mutagenic compounds are described and the levels of these species that have been detected in cooked foods are detailed.