The effects of intertemporal demand dependencies on optimal electrical energy pricing: An extension

The principal issue addressed in this paper deals with the price profile for a regulated public utility when demand and supply vary spatially and temporally and when demands are temporally interdependent. No simple cost based solution proves possible. Price is determined as a weighted average of marginal operating costs in all periods, capital costs in all periods, and delivery costs.The views expressed are those of the author and do not necessarily represent the policies of the Department of Energy or the views of other Department of Energy staff members.     

A chemical profile of recycled irrigation water in North-East Israel

The use of recycled water for irrigation purposes in agriculture is probably the most effective response to the scarcity of water resources in Israel.Base-line studies of the quality of recycled irrigation water in the Beith Alpha basin (more than 1.2 million cubic meters of recycled water) have been carried out recently.The pH, conductivity and the concentration of the ions K⁺, Na⁺, Mg²⁺, Ca²⁺, PO₄^3?, NO₃^? and Cl^? have been determined. Relationships have been established between the concentrations determined, the conductivity and the sodium adsorption ratio (S.A.R.), these being the well-established criteria for irrigation water quality.Both the chloride content and the conductivity have been demonstrated to be far above the permitted standards for irrigation water in agriculture. Similarly, the S.A.R. was found to be approaching the “red line”.Clearly, these findings reflect the man-made changes in the natural level and distribution of chemical elements in the environment studied.This study should be considered not only as an illustrative case study for the crucial importance of on-going control and assessment of man-made systems in relation to environmental consequences, but also as scientific evidence that the re-use of untreated recycled water for flood-irrigation has its long-term environmental “trade offs”.     

Tilted cellulose arrangement as a novel mechanism for hygroscopic coiling in the stork's bill awn

The sessile nature of plants demands the development of seed-dispersal mechanisms to establish new growing loci. Dispersal strategies of many species involve drying of the dispersal unit, which induces directed contraction and movement based on changing environmental humidity. The majority of researched hygroscopic dispersal mechanisms are based on a bilayered structure. Here, we investigate the motility of the stork''s bill (Erodium) seeds that relies on the tightening and loosening of a helical awn to propel itself across the surface into a safe germination place. We show that this movement is based on a specialized single layer consisting of a mechanically uniform tissue. A cell wall structure with cellulose microfibrils arranged in an unusually tilted helix causes each cell to spiral. These cells generate a macroscopic coil by spiralling collectively. A simple model made from a thread embedded in an isotropic foam matrix shows that this cellulose arrangement is indeed sufficient to induce the spiralling of the cells.     

X-ray categorization and retrieval on the organ and pathology level, using patch-based visual words

In this study we present an efficient image categorization and retrieval system applied to medical image databases, in particular large radiograph archives. The methodology is based on local patch representation of the image content, using a "bag of visual words" approach. We explore the effects of various parameters on system performance, and show best results using dense sampling of simple features with spatial content, and a nonlinear kernel-based support vector machine (SVM) classifier. In a recent international competition the system was ranked first in discriminating orientation and body regions in X-ray images. In addition to organ-level discrimination, we show an application to pathology-level categorization of chest X-ray data, the most popular examination in radiology. The system discriminates between healthy and pathological cases, and is also shown to successfully identify specific pathologies in a set of chest radiographs taken from a routine hospital examination. This is a first step towards similarity-based categorization, which has a major clinical implications for computer-assisted diagnostics.     

On forecasting electric utility fossil fuel consumption

The objective of the analysis is to develop a model to forecast the consumption of fossil fuels by electric utilities on a month-to-month basis. A scheme is devised and implemented that shares out for fossil fuel generation (net of coal), the consumption of residual fuel oil, distillate fuel oil, crude oil and natural gas. A multinomial logit specification is used whereby the share of each of these fuels is a function of relative prices, weather, time, seasonal factors and extraneous influences (e.g. a coal strike). The results, when compared to actual shares, prove to be most acceptable.     

Highly emissive nano rod-in-rod heterostructures with strong linear polarization

We report the synthesis of CdSe/CdS rod in rod core/shell heterostructures. These rods, synthesized using a seeded-growth approach, show narrow distributions of rod diameters and lengths and exhibit high emission quantum efficiencies and highly polarized emission. The degree of polarization is controlled by the inner core rod dimensions, and it is equal or up to 1.5 times higher than the polarization of equivalent sphere in rod systems. Using the method of photoselection we measure the polarization anisotropy at different excitation wavelengths and study the interplay between electronic contribution and dielectric effects in determining the absorption and emission polarization.