680 research outputs found
RF model of the distribution system as a communication channel, phase 2. Volume 4: Sofware source program and illustrations ASCII database listings
Listings of source programs and some illustrative examples of various ASCII data base files are presented. The listings are grouped into the following categories: main programs, subroutine programs, illustrative ASCII data base files. Within each category files are listed alphabetically
RF model of the distribution system as a communication channel, phase 2. Volume 3: Appendices
Program documentation concerning the design, implementation, and verification of a computerized model for predicting the steady-state sinusoidal response of radial configured distribution feeders is presented in these appendices
Pleistocene population X-plosion?
Journal ArticleIn two recent papers, Kaessmann et al. presented DNA sequence data from the X chromosome (Xq13.3) of 30 chimpanzees and 69 humans (Kaessmann et al. 1999a; Kaessmann et al. 1999b). These data bear on two longstanding questions involving late Pleistocene demographic history: (1) whether the long-term demography of humans is characterized by explosive population growth, and (2) whether chimps show population growth coinciding temporally with growth in humans
Data-Driven Abstraction-Based Control Synthesis
This paper studies formal synthesis of controllers for continuous-spacesystems with unknown dynamics to satisfy requirements expressed as lineartemporal logic formulas. Formal abstraction-based synthesis schemes rely on aprecise mathematical model of the system to build a finite abstract model,which is then used to design a controller. The abstraction-based schemes arenot applicable when the dynamics of the system are unknown. We propose adata-driven approach that computes the growth bound of the system using afinite number of trajectories. The growth bound together with the sampledtrajectories are then used to construct the abstraction and synthesise acontroller. Our approach casts the computation of the growth bound as a robust convexoptimisation program (RCP). Since the unknown dynamics appear in theoptimisation, we formulate a scenario convex program (SCP) corresponding to theRCP using a finite number of sampled trajectories. We establish a samplecomplexity result that gives a lower bound for the number of sampledtrajectories to guarantee the correctness of the growth bound computed from theSCP with a given confidence. We also provide a sample complexity result for thesatisfaction of the specification on the system in closed loop with thedesigned controller for a given confidence. Our results are founded onestimating a bound on the Lipschitz constant of the system and provideguarantees on satisfaction of both finite and infinite-horizon specifications.We show that our data-driven approach can be readily used as a model-freeabstraction refinement scheme by modifying the formulation of the growth boundand providing similar sample complexity results. The performance of ourapproach is shown on three case studies.<br
Gulf Stream recirculation experiment - Part II
This report presents trajectories and time series of velocity, pressure, and
temperature for twelve neutrally-buoyant floats launched during the Gulf Stream
Recirculation EXperiment (GUSREX) and two from earlier experiments, that
continued to operate after May 1982. These float data were obtained from
Autonomous Listening Stations (ALSs) deployed from May 1982 to August 1985.Funding was provided by the national Science Foundation under Grant Numbers OCE 81-09145 and OCE 81-1746
Assessing the impact of health technology assessment in the Netherlands
Copyright © Cambridge University Press 2008Objectives: Investments in health research should lead to improvements in health and health care. This is also the remit of the main HTA program in the Netherlands. The aims of this study were to assess whether the results of this program have led to such improvements and to analyze how best to assess the impact from health research.Methods: We assessed the impact of individual HTA projects by adapting the "payback framework" developed in the United Kingdom. We conducted dossier reviews and sent a survey to principal investigators of forty-three projects awarded between 2000 and 2003. We then provided an overview of documented output and outcome that was assessed by ten HTA experts using a scoring method. Finally, we conducted five case studies using information from additional dossier review and semistructured key informant interviews.Results: The findings confirm that the payback framework is a useful approach to assess the impact of HTA projects. We identified over 101 peer reviewed papers, more than twenty-five PhDs, citations of research in guidelines (six projects), and implementation of new treatment strategies (eleven projects). The case studies provided greater depth and understanding about the levels of impact that arise and why and how they have been achieved.Conclusions: It is generally too early to determine whether the HTA program led to actual changes in healthcare policy and practice. However, the results can be used as a baseline measurement for future evaluation and can help funding organizations or HTA agencies consider how to assess impact, possibly routinely. This, in turn, could help inform research strategies and justify expenditure for health research.This research is funded by ZonMw, the Netherlands organization for health research and development (project 945-15-001)
A simple ocean bottom hydrophone with 200 megabyte data capacity
The Woods Hole Ocean Bottom Hydrophone instrument records the digitized output of a single hydrophone sensor at rates
between 250 and 1200 samples per second with a dynamic range of 98 dB and can be deployed at depths to 600 meters. The unit's
200 megabyte disk recorder allows operation for periods up to 5 days. Designed for typical marine seismic refraction operations the
unit is reliable and simple to deploy and recover. A detailed description is provided of the instrument design and application including
transfer function, clock accuracy, data format, sample data and power requirements.Funding provided by the National Science Foundation under Grant
Nos. OCE-9019918 and OCE-8917628
RF model of the distribution system as a communication channel, phase 2. Volume 2: Task reports
Based on the established feasibility of predicting, via a model, the propagation of Power Line Frequency on radial type distribution feeders, verification studies comparing model predictions against measurements were undertaken using more complicated feeder circuits and situations. Detailed accounts of the major tasks are presented. These include: (1) verification of model; (2) extension, implementation, and verification of perturbation theory; (3) parameter sensitivity; (4) transformer modeling; and (5) compensation of power distribution systems for enhancement of power line carrier communication reliability
Dynamics of precipitation pattern formation at geothermal hot springs
We formulate and model the dynamics of spatial patterns arising during the
precipitation of calcium carbonate from a supersaturated shallow water flow.
The model describes the formation of travertine deposits at geothermal hot
springs and rimstone dams of calcite in caves. We find explicit solutions for
travertine domes at low flow rates, identify the linear instabilities which
generate dam and pond formation on sloped substrates, and present simulations
of statistical landscape evolution
- …