6,332 research outputs found
Lunar rovers and local positioning system
Telerobotic rovers equipped with adequate actuators and sensors are clearly necessary for extraterrestrial construction. They will be employed as substitutes for humans, to perform jobs like surveying, sensing, signaling, manipulating, and the handling of small materials. Important design criteria for these rovers include versatility and robustness. They must be easily programmed and reprogrammed to perform a wide variety of different functions, and they must be robust so that construction work will not be jeopardized by parts failures. The key qualities and functions necessary for these rovers to achieve the required versatility and robustness are modularity, redundancy, and coordination. Three robotic rovers are being built by CSC as a test bed to implement the concepts of modularity and coordination. The specific goal of the design and construction of these robots is to demonstrate the software modularity and multirobot control algorithms required for the physical manipulation of constructible elements. Each rover consists of a transporter platform, bus manager, simple manipulator, and positioning receivers. These robots will be controlled from a central control console via a radio-frequency local area network (LAN). To date, one prototype transporter platform frame was built with batteries, motors, a prototype single-motor controller, and two prototype internal LAN boards. Software modules were developed in C language for monitor functions, i/o, and parallel port usage in each computer board. Also completed are the fabrication of half of the required number of computer boards, the procurement of 19.2 Kbaud RF modems for inter-robot communications, and the simulation of processing requirements for positioning receivers. In addition to the robotic platform, the fabrication of a local positioning system based on infrared signals is nearly completed. This positioning system will make the rovers into a moving reference system capable of performing site surveys. In addition, a four degree mechanical manipulator especially suited for coordinated teleoperation was conceptually designed and is currently being analyzed. This manipulator will be integrated into the rovers as their end effector. Twenty internal LAN cards fabricated by a commercial firm are being used, a prototype manipulator and a range finder for a positioning system were built, a prototype two-motor controller was designed, and one of the robots is performing its first telerobotic motion. In addition, the robots' internal LAN's were coordinated and tested, hardware design upgrades based on fabrication and fit experience were completed, and the positioning system is running. The rover system is able to perform simple tasks such as sensing and signaling; coordination systems which allow construction tasks to begin were established, and soon coordinated teams of robots in the laboratory will be able to manipulate common objects
Radiative transfer through the Intergalactic Medium
We use a probabilistic method to compute the propagation of an ionization
front corresponding to the re-ionization of the intergalactic medium in a LCDM
cosmology, including both hydrogen and helium. The effects of radiative
transfer substantially boost the temperature of the ionized gas over the case
of uniform re-ionization. The resulting temperature-density relation of the
ionized gas is both non-monotonic and multiple-valued, reflecting the non-local
character of radiative transfer and suggesting that a single polytropic
relation between local gas density and temperatue is a poor description of the
thermodynamic state of baryons in the post-reionization universe.Comment: 5 pages, 7 figures, letter accepted for publication in MNRA
Towards quantum-chemical method development for arbitrary basis functions
We present the design of a flexible quantum-chemical method development
framework, which supports employing any type of basis function. This design has
been implemented in the light-weight program package molsturm, yielding a
basis-function-independent self-consistent field scheme. Versatile interfaces,
making use of open standards like python, mediate the integration of molsturm
with existing third-party packages. In this way both rapid extension of the
present set of methods for electronic structure calculations as well as adding
new basis function types can be readily achieved. This makes molsturm
well-suitable for testing novel approaches for discretising the electronic wave
function and allows comparing them to existing methods using the same software
stack. This is illustrated by two examples, an implementation of
coupled-cluster doubles as well as a gradient-free geometry optimisation, where
in both cases, an arbitrary basis functions could be used. molsturm is
open-source and can be obtained from https://molsturm.org.Comment: 15 pages and 7 figure
President-Elect's Message: Internationalization of the International Association for Dental Research
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68087/2/10.1177_00220345740530054901.pd
Greetings and Opening Remarks
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67223/2/10.1177_00220345750540022201.pd
Inclusion and Equity Committee Diverse Recruitment Task Force 3 âQualitative/Community-Specific Data Gatheringâ
The Diverse Recruitment Task Force 3 was charged to âfocus on a qualitative environmental scan of UNLV University Librariesâ current hiring practicesâ with the goal of understanding the staff perceptions of current cultural climate and recommending potential areas of focus for future changes. Task Force 3 initially planned a formal qualitative research project with IRB approval around interviewing Librariesâ staff on their experiences with the hiring process. However, this was changed to an informal town hall-style information sharing meeting after reviewing the timeline. Two meetings were held: one on November 19th, 2019 which focused on attendeesâ reflections and experiences with the hiring process, and one on December 9th, 2019 which focused on attendeesâ feedback on the recommendations of the other two task forces. Both meetings were approximately an hour long with about 20 attendees broken into four or five small groups at each meeting; a five minute recap of the Diverse Recruitment project was provided at the beginning with the rest of the time devoted to discussion. Notes were taken by task force members and then grouped by topic. See appendix for pre-prepared questions for each meeting
Chains, Antichains, and Complements in Infinite Partition Lattices
We consider the partition lattice on any set of transfinite
cardinality and properties of whose analogues do not hold
for finite cardinalities. Assuming the Axiom of Choice we prove: (I) the
cardinality of any maximal well-ordered chain is always exactly ; (II)
there are maximal chains in of cardinality ; (III) if,
for every cardinal , we have , there
exists a maximal chain of cardinality (but ) in
; (IV) every non-trivial maximal antichain in has
cardinality between and , and these bounds are realized.
Moreover we can construct maximal antichains of cardinality for any ; (V) all cardinals of the form
with occur as the number of
complements to some partition , and only these
cardinalities appear. Moreover, we give a direct formula for the number of
complements to a given partition; (VI) Under the Generalized Continuum
Hypothesis, the cardinalities of maximal chains, maximal antichains, and
numbers of complements are fully determined, and we provide a complete
characterization.Comment: 24 pages, 2 figures. Submitted to Algebra Universalis on 27/11/201
Eggpreneur Poultry Farming Workshop Slides
These workshop slides are used during training workshops as the foundation for Eggpreneurâs poultry farming and business management curriculum
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