Applying a Life-Cycle Costs Approach to Water

This working paper presents findings and recommendations from the application of a life-cycle costs approach (LCCA) to water supply services in rural communities and small towns1 in four countries -- Andhra Pradesh (India), Burkina Faso, Ghana and Mozambique

FOREIGN TOBACCO OUTLOOK

Production Economics,

Assessing Hygiene Cost-Effectiveness

This paper introduces "hygiene effectiveness levels" as a tool for standardized analysis of costs and outcomes of hygiene promotion interventions. At the time of publication, the framework was being tested in WASHCost focus countries

THE INTERNATIONAL OUTLOOK FOR U.S. TOBACCO

Crop Production/Industries,

USDA PERSPECTIVE ON THE OUTLOOK FOR COTTON

Crop Production/Industries,

Synthesis of cationic alkylated chitosans and an investigation of their rheological properties and interaction with anionic surfactant

Two methods were used to alkylate high MW chitosan with glycidyltrimethylammonium chloride (GTAC) in order to produce chitosan derivatives that are water-soluble throughout the pH range. In addition, a novel chitosan derivative was created by alkylating one of the products with the GTAC analogue Quab 342 containing C12 alkyl chains. The phase behaviour and rheological characteristics of the chitosan derivatives were studied in the presence of anionic surfactant. The derivatives were found to form soluble complexes at low and high SDS concentrations and that the Quab 342 derivative was able to form gels

Wave scattering by weakly non-uniform waveguides

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2001.Includes bibliographical references (p. 502-508).When waves propagate through a medium with small irregularities of the size of the order of many wavelengths, a number of interesting phenomena may happen such as wave localization and large sensitivity of the wave field behavior with respect to the medium irregularity variation. These phenomena occur due to the interaction of the incident wave field with the medium small irregularities, and open the possibility of designing the system irregularity to achieve a desired vibratory response. This has a variety of engineering applications, such as the the design of the sea bottom of coastal areas to provide protection against the incoming swells, or the design of the material and geometrical properties of the cross section of pipelines, risers and mooring lines such that vibration transmission is minimized. The objective of this thesis is to understand how to tune the medium small irregularity such that the interaction of the incident wave field with the medium irregularity generates a desired reflected wave field. A particular design problem of interest is the prediction of the minimum amount of changes in the medium irregularity needed to minimize wave transmission to a desired level for a given range of frequencies of interest. As a model problem, we considered disordered chains of repetitive systems with the size of the order of many wavelengths of the incident wave. We applied an asymptotic theory for wave propagation along the non-uniform chain. For weak coupling between subsystems, the asymptotic theory predicted new results, such as exponential small transmission due to wave tunneling and explained localization phenomena as a turning point problem. For strong coupling,(cont.) the asymptotic theory provided fundamental understanding of the effects of the irregularity on wave propagation. Pipelines and risers can be modeled as slender beams under tensile force. To describe well the effects of small irregularity in beams vibration, we derived asymptotically a simpler governing equation for the vibration problem. This new equation is asymptotic with respect to the beam irregularity steepness, but under the restriction of constant product of the flexural rigidity by the mass per unit length and constant tensile force, this new equation is an exact equation for the beam vibration and has a Helmholtz-like form. Inverse scattering methods for the Helmholtz-like equations can be applied to design the beam non-uniformity such that desired wave scattering properties are achieved. We also constructed a high order asymptotic solution for the scattering of mono-chromatic waves by the irregularity in slender beams. The asymptotic method used is the WKB method, which is basically a wave refraction theory, but we improved it such that wave reflection and wave mode conversion were captured. The asymptotic approach developed in the previous problems is extended and applied to the interaction of linear surface gravity waves with a bottom topography which varies slowly with respect to the length scale of the incident wave field. The asymptotic theory captured wave reflection and transmission and wave mode conversion, which leads to a more complete asymptotic representation of the wave field ...by Karl Peter Burr.Ph.D