1,604 research outputs found
F-8C digital CCV flight control laws
A set of digital flight control laws were designed for the NASA F-8C digital fly-by-wire aircraft. The control laws emphasize Control Configured Vehicle (CCV) benefits. Specific pitch axis objectives were improved handling qualities, angle-of-attack limiting, gust alleviation, drag reduction in steady and maneuvering flight, and a capability to fly with reduced static stability. The lateral-directional design objectives were improved Dutch roll damping and turn coordination over a wide range in angle-of-attack. An overall program objective was to explore the use of modern control design methodilogy to achieve these specific CCV benefits. Tests for verifying system integrity, an experimental design for handling qualities evaluation, and recommended flight test investigations were specified
Control networks for the Galilean satellites, November 1979
Pictures of the four Galilean satellites taken as the two Voyager spacecraft approached Jupiter during March and July 1979 are presented. Control nets of the Galilean satellites, computed photogrammetrically, and measurements of the mean radii are presented. The pictures in the control nets are identified, the coordinates of the control points are given, and identifications of some of the control points are shown on figures. The use of star field pictures to compute the focal lengths of the camera is discussed and the geometric relationship between the narrow and wide and angle cameras is reported. A description of the coordinate systems of the Galilean satellites is presented and the status of the control net computations is reported
Demand-Side Programs to Stimulate Adoption of Broadband: What Works?
We examine the evidence available on the efficacy of demand-side programs intended to stimulate broadband adoption. We review studies that attempt to measure results. Our suggestions for future program evaluations are to include cost-benefit analysis as a standard part of program review and to make clear that the purpose of evaluation is to assess progress made toward the ultimate policy goals rather than the program’s proximate implementation goals. Appropriate data must be collected to draw conclusions, and appropriate statistical methods must be used to determine the causal impacts of a program. This has rarely been done to date
Evaluating the Impact of the American Recovery and Reinvestment Act’s BTOP Program on Broadband Adoption
The American Recovery and Reinvestment Act’s Broadband Technology Opportunities Program (BTOP) spent $4.7B during 2009-2013 to, int. al, increase broadband adoption in underserved communities. We characterize the BTOP grants and examine the impact of the awards on broadband adoption. Econometric specifications controlling for award endogeneity related to observed and unobserved county-level factors find that spending is apparently associated with increased broadband adoption. Further investigation, however, reveals that the impacts of spending are nonlinear and even nonmonotonic over the range of county-level BTOP spending in the data. Controlling for trends to reduce the potential for spurious correlation between spending and outcomes removes most of the significance of the results. We conclude with three lessons for policymakers derived from the uncertain outcomes of BTOP spending found in our exploration
Number-of-Particle Fluctuations and Stability of Bose-Condensed Systems
In this paper we show that a normal total number-of-particle fluctuation can
be obtained consistently from the static thermodynamic relation and dynamic
compressibility sum rule. In models using the broken U(1) gauge symmetry, in
order to keep the consistency between statics and dynamics, it is important to
identify the equilibrium state of the system with which the density response
function is calculated, so that the condensate particle number , the
number of thermal depletion particles , and the number of
non-condensate particles can be unambiguously defined. We also show
that the chemical potential determined from the Hugenholtz-Pines theorem should
be consistent with that determined from the equilibrium equation of state. The
anomalous fluctuation of the number of non-condensate particles is an
intrinsic feature of the broken U(1) gauge symmetry. However, this anomalous
fluctuation does not imply the instability of the system. Using the random
phase approximation, which preserves the U(1) gauge symmetry, such an anomalous
fluctuation of the number of non-condensate particles is completely absentComment: 9 pages, submitted to PR
Oust the Louse: Does Political Pressure Discipline Regulators?
We consider a possible determinant of regulatory decisions by public utility commissioners: the desire to remain in office. We examine regulatory exit, where a regulator leaves a commission during a term or is not re-appointed/re-elected. With data from US states, we empirically investigate several hypotheses motivated by a political agency model of regulatory decision-making. Our empirical results generally support the hypotheses, including that higher electricity prices lead to ousting, that ousting is less common where it is more costly for the principal to whom the regulator reports, and that ousting is more likely where regulators are more accountable or are more likely to share the principal‘s preferences. Furthermore, the results provide limited evidence that regulatory exit is not due mainly to the revolving door. Ousting also appears to lower future electricity prices
Prime Example Ingress Reframing the Pervasive Game Design Framework (PGDF)
The growing availability of mobile communication infrastructure over the last decade has contributed significantly to the maturity of Pervasive Gaming. The massive suc-cess of games such as Ingress and Pokémon Go made pervasive gaming a viable op-tion for transforming learning. By its adaptability to location and context, pervasive technology is a valuable support for the design of engaging learning experiences. De-spite profound examples of pervasive gaming as learning tool, there is still a lack of reliable methodologies to construct purposeful pervasive learning experiences. The Pervasive Game Design Framework (PGDF) is intended to fill this gap. In this article, we present the PGDF using the example of Ingress. Ingress is a prominent pervasive game, as it has received huge attention since its appearance in 2012. A large commu-nity of players and third-party-tool suppliers has created a rich set of experiences since then. In this research, we examine Ingress according to PGDF’s categories based on a survey among long-term Ingress players (N=133). Founded on this analysis we identify three main benefits for Ingress players. Furthermore, we discuss the conse-quences of these findings on the PGDF. Summarizing, this work strengthens the ap-plicability of the PGDF, in order to enable the construction of enriched pervasive learn-ing experiences
Collective Antenna Effects in the Terahertz and Infrared Response of Highly Aligned Carbon Nanotube Arrays
We study macroscopically-aligned single-wall carbon nanotube arrays with
uniform lengths via polarization-dependent terahertz and infrared transmission
spectroscopy. Polarization anisotropy is extreme at frequencies less than
3 THz with no sign of attenuation when the polarization is perpendicular
to the alignment direction. The attenuation for both parallel and perpendicular
polarizations increases with increasing frequency, exhibiting a pronounced and
broad peak around 10 THz in the parallel case. We model the electromagnetic
response of the sample by taking into account both radiative scattering and
absorption losses. We show that our sample acts as an effective antenna due to
the high degree of alignment, exhibiting much larger radiative scattering than
absorption in the mid/far-infrared range. Our calculated attenuation spectrum
clearly shows a non-Drude peak at 10 THz in agreement with the
experiment.Comment: 5 pages, 5 figure
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