Design and evaluation of an integrated GPS/INS system for shallow-water AUV Navigation

The major problem addressed by this research is the large and/or expensive equipment required by a conventional navigation system to accurately determine the position of an Autonomous Underwater Vehicle (AUV) during all phases of an underwater search or mapping mission. The approach taken was to prototype an integrated navigation system which combines Global Positioning System (OPS) and Inertial Measurement Unit (IMU), waterspeed and heading information using Kalman filtering techniques. Actual implementation was preceded by a computer simulation to test where the unit would fit into a larger hardware and software hierarchy of an AUV. The system was then evaluated in experiments which began with land based cart tests and progressed to open water trials where the unit was placed in a towed body behind a boat and alternately submerged and surfaced to provide periodic OPS updates to the Inertial Navigation System (INS). Test results and qualitative error estimates indicate that submerged navigation accuracy comparable to that of differential OPS may be attainable for periods of 30 seconds or more with low cost components of a small physical size.http://archive.org/details/designndevaluati1094535102NANAU.S. Navy (U.S.N.) authors

Confidence and the Transmission of Government Spending Shocks

There seems to be a widespread belief among economists, policy-makers, and members of the media that the "confidence'" of households and businesses is a critical component in the transmission of fiscal policy shocks into economic activity. We take this proposition to the data using standard structural VARs with government spending and aggregate output augmented to include empirical measures of consumer or business confidence. We also estimate non-linear VAR specifications to allow for differential impacts of government spending in "normal'' times versus recessions. In normal times confidence does not react significantly to unexpected increases in government spending and spending multipliers are in the neighborhood of one; during recessions confidence rises and spending multipliers are significantly larger. We then quantify the importance of the systematic response of confidence to spending shocks for the spending multiplier and find that, in normal times, confidence is irrelevant for the transmission of government spending shocks to output, but during periods of economic slack it is important. We argue and present evidence that it is not confidence per se – in the sense of pure sentiment – that matters for the transmission of spending shocks during downturns, but rather that the composition of spending during a downtown is different. In particular, spending shocks during downturns predict future productivity improvements through a persistent increase in government investment relative to consumption, which is in turn reflected in higher measured confidence.

Comparison of methods for sampling particulate emissions from tires under different test environments

Traffic-related emissions are strongly criticised by the public because they contribute to climate change and are classified as hazardous to health. Combustion engine emissions have been regulated by limit values for almost three decades. There is currently no legal limit for non-exhaust emissions, which include tire wear particle emissions and resuspension. As a result, the percentage of total vehicle emissions has risen continuously. Some of the particles emitted can be assigned to the size classes of particulate matter (≤10 µm) and are therefore of particular relevance to human health. The literature describes a wide range of concepts for sampling and measuring tire wear particle emissions. Because of the limited number of studies, the mechanisms involved in on-road tests and their influence on the particle formation process, particle transport and the measuring ability can only be described incompletely. The aim of this study is to compare test bench and on-road tests and to assess the influence of selected parameters. The first part describes the processes of particle injection and particle distribution. Based on this, novel concepts for sampling and measurement in the laboratory and in the field are presented. The functionality and the mechanisms acting in each test environment are evaluated on the basis of selected test scenarios. For example, emissions from external sources, the condition of the road surface and the influence of the driver are identified as influencing factors. These analyzes are used to illustrate the complexity and limited reproducibility of on-road measurements, which must be taken into account for future regulations

Inertial Motion Tracking for Inserting Humans into a Networked Synthetic Environment

Inertial/Magnetic tracking is based on the use of sensors containing three orthogonally mounted angular rate sensors, three orthogonal linear accelerometers and three orthogonal magnetometers to determine independently the orientation of each link of an articulated rigid body. Inertial/magnetic orientation tracking could be applied to a broad range of problems which require real-time tracking of an articulated structure without being continuously dependent upon an artificially generated source. This research focuses on the goal of developing and demonstrating wireless full body tracking using MARG sensor modules.U.S. Army Research OfficeW911NF-04-1-030

Rigid Body Dynamics, Inertial Reference Frames, and Graphics Coordinate Systems: A Resolution of Conflicting Conventions and Terminology

Prepared for: NPS MOVES Academic GroupApproved for public release; distribution is unlimited

Uncertainty and Economic Activity: Evidence from Business Survey Data

What is the impact of time-varying business uncertainty on economic activity? Using partly confidential business survey data from the U.S. and Germany in structural VARs, we find that positive innovations to business uncertainty lead to prolonged declines in economic activity. In contrast, their high-frequency impact is small. We find no evidence of the "wait-and-see"-effect – large declines of economic activity on impact and subsequent fast rebounds – that the recent literature associates with positive uncertainty shocks. Rather, positive innovations to business uncertainty have effects similar to negative business confidence innovations. Once we control for their low-frequency effect, we find little statistically or economically significant impact of uncertainty innovations on activity. We argue that high uncertainty events are a mere epiphenomenon of bad economic times: recessions breed uncertainty.

Inertial and Magnetic Posture Tracking for Inserting Humans Into Networked Virtual Environments

Proceedings of ACM Symposium on Virtual Reality Software & Technology (VRST 2001), Banff, Alberta, Canada, 15 - 17 November 2001, pp.9-16.Accepted/Published Conference Pape

Generation and characterization of a mitotane-resistant adrenocortical cell line

Mitotane is the only drug approved for the therapy of adrenocortical carcinoma (ACC). Its clinical use is limited by the occurrence of relapse during therapy. To investigate the underlying mechanisms in vitro, we here generated mitotane-resistant cell lines. After long-term pulsed treatment of HAC-15 human adrenocortical carcinoma cells with 70 µM mitotane, we isolated monoclonal cell populations of treated cells and controls and assessed their respective mitotane sensitivities by MTT assay. We performed exome sequencing and electron microscopy, conducted gene expression microarray analysis and determined intracellular lipid concentrations in the presence and absence of mitotane. Clonal cell lines established after pulsed treatment were resistant to mitotane (IC50 of 102.2 ± 7.3 µM (n = 12) vs 39.4 ± 6.2 µM (n = 6) in controls (biological replicates, mean ± s.d., P = 0.0001)). Unlike nonresistant clones, resistant clones maintained normal mitochondrial and nucleolar morphology during mitotane treatment. Resistant clones largely shared structural and single nucleotide variants, suggesting a common cell of origin. Resistance depended, in part, on extracellular lipoproteins and was associated with alterations in intracellular lipid homeostasis, including levels of free cholesterol, as well as decreased steroid production. By gene expression analysis, resistant cells showed profound alterations in pathways including steroid metabolism and transport, apoptosis, cell growth and Wnt signaling. These studies establish an in vitro model of mitotane resistance in ACC and point to underlying molecular mechanisms. They may enable future studies to overcome resistance in vitro and improve ACC treatment in vivo