1,112 research outputs found
Investigations of high power problems in space shuttle antenna designs
A study program is discussed which includes a survey of industry and government laboratories and was undertaken to determine the state of the art in dealing with problems of high power levels in reentry antenna design. A laboratory program to develop techniques for testing dielectric materials for effects on RF transmission is also considered, with emphasis on high power applications in space and reentry flights. The study program resulted in a set of guidelines for avoiding breakdown in antenna design. A discussion of temperature effects on dielectric breakdown is also given. From the laboratory program, a description is presented of techniques for (1) heating with a carbon arc image furnace, (2) temperature measurement (using thermocouples and an infrared pyrometer), (3) mass spectrometric monitoring of outgassing, (4) testing for RF breakdown in both heated dielectrics and the dielectric/air and dielectric/plasma interfaces. Data and observations are reported from technique development using candidate shuttle materials falling into three categories: (1) lightweight refractory foams, (2) dense RF window materials, and (3) ablative materials
On the connection of Gamma-rays, Dark Matter and Higgs searches at LHC
Motivated by the upcoming Higgs analyzes we investigate the importance of the
complementarity of the Higgs boson chase on the low mass WIMP search in direct
detection experiments and the gamma-ray emission from the Galactic Center
measured by the Fermi-LAT telescope in the context of the . We obtain the relic abundance, thermal cross section,
the WIMP-nucleon cross section in the low mass regime and network them with the
branching ratios of the Higgs boson in the model. We conclude that the Higgs
boson search has a profound connection to the dark matter problem in our model,
in particular for the case that ( GeV) the BR(
WIMPs) . This scenario could explain this plateau of any mild
excess regarding the Higgs search as well as explain the gamma-ray emission
from the galactic center through the channel with a WIMP in the mass
range of 25-45 GeV, while still being consistent with the current limits from
XENON100 and CDMSII. However, if the recent modest excesses measured at LHC and
TEVATRON are confirmed and consistent with a standard model Higgs boson this
would imply that GeV, consequently ruling out any attempt to
explain the Fermi-LAT observations.Comment: 8 pages, 9 figure
A rule-based method for discovering trajectory profiles
The discovery of people profiles such as workers, students, families with kids, etc, is of interest for several application domains. For decades, such information has been extracted using census data, and more recently, from social networks, where people’s profile is clearly defined. A new type of data that has not been explored for discovering profiles, but which stores the real movement of people, are trajectories of moving objects. In this paper we propose a rule-based method to represent socio-demographic profiles, a moving object history model to summarize the daily movement of individuals, and define similarity functions for matching the profile model and the history model. We evaluate the method for single and multiple profile discovery.The discovery of people profiles such as workers, students, families with kids, etc, is of interest for several application domains. For decades, such information has been extracted using census data, and more recently, from social networks, where people's profile is clearly defined. A new type of data that has not been explored for discovering profiles, but which stores the real movement of people, are trajectories of moving objects. In this paper we propose a rule-based method to represent socio-demographic profiles, a moving object history model to summarize the daily movement of individuals, and define similarity functions for matching the profile model and the history model. We evaluate the method for single and multiple profile discovery
Estimation of genetic parameters and selection of high-yielding, upright common bean lines with slow seed-coat darkening.
Slow seed coat darkening is desirable in common bean cultivars and genetic parameters are important to define breeding strategies. The aims of this study were to estimate genetic parameters for plant architecture, grain yield, grain size, and seed-coat darkening in common bean; identify any genetic association among these traits; and select lines that associate desirable phenotypes for these traits. Three experiments were set up in the winter 2012 growing season, in Santo Antônio de Goiás and Brasília, Brazil, including 220 lines obtained from four segregating populations and five parents. A triple lattice 15 x 15 experimental design was used. The traits evaluated were plant architecture, grain yield, grain size, and seed-coat darkening. Analyses of variance were carried out and genetic parameters such as heritability, gain expected from selection, and correlations, were estimated. For selection of superior lines, a ?weight-free and parameter-free? index was used. The estimates of genetic variance, heritability, and gain expected from selection were high, indicating good possibility for success in selection of the four traits. The genotype x environment interaction was proportionally more important for yield than for the other traits. There was no strong genetic correlation observed among the four traits, which indicates the possibility of selection of superior lines with many traits. Considering simultaneous selection, it was not possible to join high genetic gains for the four traits. Forty-four lines that combined high yield, more upright plant architecture, slow darkening grains, and commercial grade size were selected
DeltaZ: An Accessible Compliant Delta Robot Manipulator for Research and Education
This paper presents the DeltaZ robot, a centimeter-scale, low-cost,
delta-style robot that allows for a broad range of capabilities and robust
functionalities. Current technologies allow DeltaZ to be 3D-printed from soft
and rigid materials so that it is easy to assemble and maintain, and lowers the
barriers to utilize. Functionality of the robot stems from its three
translational degrees of freedom and a closed form kinematic solution which
makes manipulation problems more intuitive compared to other manipulators.
Moreover, the low cost of the robot presents an opportunity to democratize
manipulators for a research setting. We also describe how the robot can be used
as a reinforcement learning benchmark. Open-source 3D-printable designs and
code are available to the public.Comment: IROS 2022, first two authors contributed equall
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