Approaches to implementing deterministic models in a probabilistic framework

The increasing use of results from probabilistic risk assessments in the decision-making process makes it ever more important to eliminate simplifications in probabilistic models that might lead to conservative results. One area in which conservative simplifications are often made is modeling the physical interactions that occur during the progression of an accident sequence. This paper demonstrates and compares different approaches for incorporating deterministic models of physical parameters into probabilistic models; parameter range binning, response curves, and integral deterministic models. An example that combines all three approaches in a probabilistic model for the handling of an energetic material (i.e. high explosive, rocket propellant,...) is then presented using a directed graph model

Improving nurse staffing measures: Discharge day measurement in adjusted patient days of care

Previous research cannot account for the discrepancy between registered nurse (RN) reports of understaffing and studies showing slight improvement. One reason may be that adjusted patient days of care (APDC) underestimates patient load. Using data from all Pennsylvania acute care general hospitals for the years 1994 through 1997, we found that APDC is underestimated by two hours. After adjusting APDC, we examined the difference in nurse staffing over the period 1991-2000 before and after the adjustment. We found a significant difference between unadjusted and adjusted measures. However, when applied to the changes in nurse staffing between 1991 and 2000, the difference was not enough to account for the discrepancy between reports and data. Other measurement and conceptual problems may exist in terms of patients\u27 increasing acuity levels, patients\u27 declining lengths of stay and the associated greater proportion of nurse time devoted to admission and discharge, and lack of recent data in some empirical studies

Streaming birefringence in extensional flow of polymer solutions

The stress and birefringence in liquid filaments undergoing an extensional flow were measured in an isothermal filament-spinning apparatus. In conjunction with these measurements, an experimental arrangement is described which, as subsequent analyses show, overcomes the difficulties associated with the measurement of birefringence in this geometry. The fluids studied were 1 1/2% and 2 1/2% solutions of two polyacrylamides (Separan AP 30 and Separan AP 273) in a 1 : 1 water/glycerol mixture and a 5% solution of polystyrene (Styron 686) in Aroclor 1254. For all solutions studied, the measured birefringence exhibited a non-linear relation to the principal stress difference. In addition, for the polystyrene/Aroclor solution, the birefringence measured in extension was nearly two orders of magnitude higher than the birefringence in shear at comparable deformation rates. These observations imply a greater degree of molecular orientation is produced by the extensional flow than the shear flow and suggest that birefringence data obtained in shear and extension are useful complements to depict a wider range of stress-optical behavior. On a mesuré l'éffet Maxwell, c'est-à-dire la biréfringence en fonction de la tension, dans des filaments liquides de solution polymérique soumise a un écoulement extensionel. Au moyen d'un appareil spécial, on a réussi a resoudre les problèmes d'optique provenant de cette configuration expérimentale. Avec cet appareil, on a étudié plusieurs solutions aqueuses des polyacrylamides en glycérine aussi bien q'une solution du polystyrene en Arochlor 1254 (polychlor biphenyl).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47202/1/397_2005_Article_BF01736956.pd

Mapping Physical Formats to Logical Models to Extract Data and Metadata: The Defuddle Parsing Engine

Scientists, fueled by the desire for systems-level understanding of phenomena, increasingly need to share their results across multiple disciplines. Accomplishing this requires data to be annotated, contextualized, and readily searchable and translated into other formats. While these requirements can be addressed by custom programming or obviated by community standardization, neither approach has ‘solved’ the problem. In this paper, we describe a complementary approach – a general capability for articulating the format of arbitrary textual and binary data using a logical data model, expressed in XML-Schema, which can be used to provide annotation and context, extract metadata, and enable translation. This work is based on the draft specification for the Data Format Description Language and our open source “Defuddle” parser. We present an overview of the specification, detail the design of Defuddle, and discuss the benefits and challenges of this general approach to enabling discovery and sharing of diverse data sets

ARSENIC REMOVAL IN WATER TREATMENT FACILITIES: SURVEY OF GEOCHEMICAL FACTORS AND PILOT PLANT EXPERIMENTS

Midwest Technology Assistance Center for Small Community Water Supplies (MTAC)Ope