NASA Scientific and Technical Aerospace Reports

The authors conducted research to study the implications of and provide statistical solutions to regression effects when
assessing the effectiveness of an intervention. The authors developed methods to estimate the intervention effect and adjust
for the regression effect in a nonrandomized study with a mismeasured binary response and a binary response outcome. The
extended the proposed methods to estimate the placebo and intervention effects in placebo-controlled studies and conducted
a number of simulation studies to mimic actual medical situations. The authors quantified regression effect in various probable
clinical scenarios, and proposed statistical methods to remove bias. The authors developed a statistical model for estimating
the treatment effect where the selection variable is continuous and the outcome is binary, but were unable to obtain a converged
estimation of treatment effect. The authors proposed four possible types of validation studied to be applied to single-armed,
non-controlled studies. Finally, the authors analyzed restenosis and otitis media data for illustration. The proposed research
is innovative and significant because current methods for adjustment for RTM have focused on normally distributed data, and
are no longer adequate to cope with the complexities of health services outcomes and clinical studies in the real world.
NTIS
Statistical Analysis; Mathematical Models
20040047043 Helsinki Univ. of Technology, Espoo, Finland
Delay Estimation in Long-Code Asynchronous DS/CDMA Systems Using Multiple Antennas
Sirbu, M.; Koivunen, V.; 2003; 32 pp.; In English
Report No.(s): PB2004-102806; Copyright; Avail: National Technical Information Service (NTIS)
This paper addresses the problem of propagation delay estimation in asynchronous long-code DS/CDMA multi-user
systems. Almost all the methods proposed so far in the literature for propagation delay estimation are derived for short codes
and the knowledge of the codes is exploited by the estimators. In long-code CDMA, the spreading code is aperiodic and the
methods developed for short codes may not be used or may increase the complexity significantly. For example, in the subspace
based estimators, the aperiodic nature of the code may require subspace tracking. We propose a method for joint channel and
delay estimation in uplink DS/CDMA using multiple antennas.
NTIS
Antennas; Code Division Multiple Access
20040047080 Swedish Defence Research Establishment, Stockholm, Sweden
The Information Flow in Network Based Defense
Falk, L.; 2003; 40 pp.; In English
Report No.(s): PB2004-102684; FOI-R-0658-SE; No Copyright; Avail: CASI; A03, Hardcopy
In order to clarify the concept of information warfare the flow of information is studied in network centric defense
systems. Several systems are suggested as suitable objects for further investigation in terms of information flow. This view
is pedagogically useful and tends to simplify discussions about future sensors systems by introducing information flow as a
common concept. The amount of available information is a convenient measure of performance if comparisons are based on
the principle that optimal decisions require that all available information is considered. This rule can be proved within the
context of Bayesiansk statistics and is illustrated by practical examples concerning the performance of radar systems. The
conclusion is that the ideas of information flow are best tested on existing sensor networks, e.g. STRIL, in order to study how
information flow measures the function. The goal is to describe the effect of jamming in quantitative terms and investigate the
effect of bottle necks on information flow.
NTIS
Information Flow; Electronic Warfare
20040047093 Helsinki Univ. of Technology, Espoo, Finland
Load Balancing by MPLS in Differentiated Services Networks
Susitaival, R.; Sep. 2002; 86 pp.; In English
Report No.(s): PB2004-104412; Copyright; Avail: National Technical Information Service (NTIS)
In IP routing, forwarding decisions are made independently in each router. Multi Protocol Label Switching (MPLS) as
a new technique assigns a short label to each packet at the ingress node of MPLS network and packets are forwarded according
to these labels. The most significant application of MPLS is the Traffic Engineering, which is used to optimize the performance
of networks. The capability of MPLS of explicit routing as well as of splitting of the traffic on several paths allows load
balancing. The goal of this thesis is to study a flow allocation that minimizes the mean delay of the network. The thesis
concentrates on the minimum-delay algorithm presented by Gallager and its two approximations. The first approximation
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