Modeling residential demand for natural gas as a function of the coldness of the month

A simple two-parameter model of the monthly demand for natural gas for space heating is developed. First, a simple indicator of the coldness of the month labeled “modified degree days” is presented. Both aggregate monthly demand and monthly demand for a single unit are modeled as a function of this indicator. The model has two parameters, a reference temperature which reflects the internal temperature and free heat contribution and a slope parameter which reflects the thermal behavior of the dwelling. Variation in these two parameters is related to characteristics of the dwelling. Finally, the effect of the onset of the energy crisis on the two parameters is assessed.     

Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003)

Large quantities of phosphate present in wastewater is one of the main causes of eutrophication that negatively affects many natural water bodies, both fresh water and marine. It is desirable that water treatment facilities remove phosphorus from the wastewater before they are returned to the environment. Total removal or at least a significant reduction of phosphorus is obligatory, if not always fulfilled, in most countries. This comprehensive review summarizes the current status in phosphorus-removal technologies from the most common approaches, like metal precipitation, constructed wetland systems, adsorption by various microorganisms either in a free state or immobilized in polysaccharide gels, to enhanced biological phosphorus removal using activated sludge systems, and several innovative engineering solutions. As chemical precipitation renders the precipitates difficult, if not impossible, to recycle in an economical industrial manner, biological removal opens opportunities for recovering most of the phosphorus and beneficial applications of the product. This review includes the options of struvite (ammonium-magnesium-phosphate) and hydroxyapatite formation and other feasible options using, the now largely regarded contaminant, phosphorus in wastewater, as a raw material for the fertilizer industry. Besides updating our knowledge, this review critically evaluates the advantage and difficulties behind each treatment and indicates some of the most relevant open questions for future research.     

Removal of ammonium and phosphorus ions from synthetic wastewater by the microalgae Chlorella vulgaris coimmobilized in alginate beads with the microalgae growth-promoting bacterium Azospirillum brasilense

Coimmobilization of the freshwater microalga Chlorella vulgaris in alginate beads with the microalgae growth-promoting bacterium Azospirillum brasilense under semi-continuous synthetic wastewater culture conditions significantly increased the removal of ammonium and soluble phosphorus ions compared to immobilization of the microalgae alone. In continuous or batch cultures removal of these ions followed a similar trend but was less efficient than in semi-continuous culture. It is proposed that coimmobilization of a microalgae with microalgae growth-promoting bacteria can serve as a tool in devising novel wastewater treatments.     

Mood and global–local focus: Priming a local focus reverses the link between mood and global–local processing.

Positive moods promote a focus on the forest (global focus) and negative moods, a focus on the trees (local focus). Is this well-established link fixed or variable? Does it reflect a direct influence of affect, as usually assumed, or is it frequently observed simply because a global perspective is often dominant? If affect serves as information about the value of currently accessible inclinations, and a global focus is generally the default perspective, then the global focus of positive affect and local focus of negative affect might be variable rather than fixed. Two experiments tested this hypothesis using different mood inductions, different tests of global–local focus, and different methods of inducing global and local perspectives. In each, we discovered that positive affect empowered whatever focus was momentarily dominant. Thus, whether individuals in happy moods saw the forest or the trees depended only on which of the two had been primed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maximum Likelihood Localization of a Diffusive Point Source Using Binary Observations

In this paper, we investigate the problem of localization of a diffusive point source of gas based on binary observations provided by a distributed chemical sensor network. We motivate the use of the maximum likelihood (ML) estimator for this scenario by proving that it is consistent and asymptotically efficient, when the density of the sensors becomes infinite. We utilize two different estimation approaches, ML estimation based on all the observations (i.e., batch processing) and approximate ML estimation using only new observations and the previous estimate (i.e., real time processing). The performance of these estimators is compared with theoretical bounds and is shown to achieve excellent performance, even with a finite number of sensors     

Fault tolerant mechanism design

We introduce the notion of fault tolerant mechanism design, which extends the standard game theoretic framework of mechanism design to allow for uncertainty about execution. Specifically, we define the problem of task allocation in which the private information of the agents is not only their costs of attempting the tasks but also their probabilities of failure. For several different instances of this setting we present both, positive results in the form of mechanisms that are incentive compatible, individually rational, and efficient, and negative results in the form of impossibility theorems.