1,091 research outputs found
Lunar base launch and landing facilities conceptual design
The purpose of this study was to perform a first look at the requirements for launch and landing facilities for early lunar bases and to prepared conceptual designs for some of these facilities. The emphasis of the study is on the facilities needed from the first manned landing until permanent occupancy, the Phase 2 lunar base. Factors including surface characteristics, navigation system, engine blast effects, and expected surface operations are used to develop landing pad designs, and definitions fo various other elements of the launch and landing facilities. Finally, the dependence of the use of these elements and the evolution of the facilities are established
Employee Receptivity to Three Hundred Sixty Degree Feedback Systems as a Function of Employee Trust and Employee Commitment: An Exploratory Study
The purpose of this quantitative exploratory study was to determine what affect, if any, employee trust, employee commitment, psychological androgyny (an employee sex-role inventory), and various demographic variables have on employee receptivity to 360-degree feedback (R360). Two organizations participated in the study. The first is a large university located in New York; the second is a small consulting firm located in California. A total of 62 participants responded to the 77-item Internet-based survey. The survey was composed of psychometrically adequate constructs developed in earlier studies. Employee trust, a 12-item construct, consisted of 8 items that measured trust in supervisor and 4 items that measured trust in the organization. Employee commitment and R360 used a 7-item construct and 5-item construct, respectively. Four independent variables were found to be statistically linked to R360. Employee commitment, employee trust, income, and level of education accounted for 37.5% of the variance in R360 (p = .044, .027, .028, and .008, respectively). The research findings could have consequential implications, particularly if broader studies find similar results. Specifically, organizational leaders and managers would be able to make informed decisions about possible implementation of 360-degree feedback systems depending on the organizational climate
Termination Casts: A Flexible Approach to Termination with General Recursion
This paper proposes a type-and-effect system called Teqt, which distinguishes
terminating terms and total functions from possibly diverging terms and partial
functions, for a lambda calculus with general recursion and equality types. The
central idea is to include a primitive type-form "Terminates t", expressing
that term t is terminating; and then allow terms t to be coerced from possibly
diverging to total, using a proof of Terminates t. We call such coercions
termination casts, and show how to implement terminating recursion using them.
For the meta-theory of the system, we describe a translation from Teqt to a
logical theory of termination for general recursive, simply typed functions.
Every typing judgment of Teqt is translated to a theorem expressing the
appropriate termination property of the computational part of the Teqt term.Comment: In Proceedings PAR 2010, arXiv:1012.455
A new numerical method for obtaining gluon distribution functions , from the proton structure function
An exact expression for the leading-order (LO) gluon distribution function
from the DGLAP evolution equation for the proton structure
function for deep inelastic scattering has
recently been obtained [M. M. Block, L. Durand and D. W. McKay, Phys. Rev.
D{\bf 79}, 014031, (2009)] for massless quarks, using Laplace transformation
techniques. Here, we develop a fast and accurate numerical inverse Laplace
transformation algorithm, required to invert the Laplace transforms needed to
evaluate , and compare it to the exact solution. We obtain accuracies
of less than 1 part in 1000 over the entire and spectrum. Since no
analytic Laplace inversion is possible for next-to-leading order (NLO) and
higher orders, this numerical algorithm will enable one to obtain accurate NLO
(and NNLO) gluon distributions, using only experimental measurements of
.Comment: 9 pages, 2 figure
Lunar and Martian hardware commonality
A number of different hardware elements were examined for possible Moon/Mars program commonality. These include manned landers; cargo landers, a trans-Mars injection (TMI) stage, traverse vehicles, unmanned surface rovers, habitation modules, and power supplies. Preliminary analysis indicates that it is possible to build a common two-stage manned lander. A single-stage, reusable lander may be practical for the lunar cast, but much less so for the Martian case, and commonality may therefore exist only at the subsystem level. A modified orbit transfer vehicle was examined as a potential cargo lander. Potential cargoes to various destinations were calculated for a Shuttle external tank sized TMI stage. A nuclear powered, long range traverse vehicle was conceptually designed and commonality is considered feasible. Short range, unmanned rovers can be made common without great effort. A surface habitation module may be difficult to make common due to difficulties in landing certain shapes on the Martian surface with aerobraking landers. Common nuclear power sources appear feasible. High temperature radiators appear easy to make common. Low temperature radiators may be difficult to make common. In most of these cases, Martian requirements determine the design
Comparing introductory and beyond-introductory students' reasoning about uncertainty
Uncertainty is an important concept in physics laboratory instruction.
However, little work has examined how students reason about uncertainty beyond
the introductory (intro) level. In this work we aimed to compare intro and
beyond-intro students' ideas about uncertainty. We administered a survey to
students at 10 different universities with questions probing procedural
reasoning about measurement, student-identified sources of uncertainty, and
predictive reasoning about data distributions. We found that intro and
beyond-intro students answered similarly on questions where intro students
already exhibited expert-level reasoning, such as in comparing two data sets
with the same mean but different spreads, identifying limitations in an
experimental setup, and predicting how a data distribution would change if more
data were collected. For other questions, beyond-intro students generally
exhibited more expert-like reasoning than intro students, such as when
determining whether two sets of data agree, identifying principles of
measurement that contribute to spread, and predicting how a data distribution
would change if better data were collected. Neither differences in student
populations, lab courses taken, nor research experience were able to fully
explain the variability between intro and beyond-intro student responses. These
results call for further research to better understand how students' ideas
about uncertainty develop beyond the intro level.Comment: 19 pages, 12 figure
A rewriting view of simple typing
This paper shows how a recently developed view of typing as small-step abstract reduction, due to Kuan, MacQueen, and Findler, can be used to recast the development of simple type theory from a rewriting perspective. We show how standard meta-theoretic results can be proved in a completely new way, using the rewriting view of simple typing. These meta-theoretic results include standard type preservation and progress properties for simply typed lambda calculus, as well as generalized versions where typing is taken to include both abstract and concrete reduction. We show how automated analysis tools developed in the term-rewriting community can be used to help automate the proofs for this meta-theory. Finally, we show how to adapt a standard proof of normalization of simply typed lambda calculus, for the rewriting approach to typing
Context affects student thinking about sources of uncertainty in classical and quantum mechanics
Measurement uncertainty is an important topic in the undergraduate laboratory
curriculum. Previous research on student thinking about experimental
measurement uncertainty has focused primarily on introductory-level students'
procedural reasoning about data collection and interpretation. In this paper,
we extended this prior work to study upper-level students' thinking about
sources of measurement uncertainty across experimental contexts, with a
particular focus on classical and quantum mechanics contexts. We developed a
survey to probe students' thinking in the generic question ``What comes to mind
when you think about measurement uncertainty in [classical/quantum]
mechanics?'' as well as in a range of specific experimental scenarios. We found
that students primarily focused on limitations of the experimental setup in
classical mechanics and principles of the underlying physics theory in quantum
mechanics. Our results suggest that students need careful scaffolding to
identify principles in appropriate classical experimental contexts and
limitations in appropriate quantum experimental contexts. We recommend that
future research probe how instruction in both classical and quantum contexts
can help students better understand the range of sources of uncertainty present
in classical and quantum experiments.Comment: 15 pages, 8 figure
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Ground penetrating radar mini-CRADA final report
The purpose of this project was to determine the feasibility of using ground penetrating radar (GPR) to assess the ease of excavability prior to and during trenching operations. The project partners were EnTech Engineering Inc., Vermeer Manufacturing Co., and AlliedSignal Federal Manufacturing & Technology (FM&T)/Kansas City Plant (KCP). Commercial GPRs were field tested as well as a system developed at AlliedSignal FM&T. The AlliedSignal GPR was centered around a HP8753 Network Analyzer instrument. Commercial GPR antennas were connected to the analyzer and data was collected under control of software written for a notebook PC. Images of sub-surface features were generated for varied system parameters including: frequency, bandwidth, FFT windowing, gain, antenna orientation, and surface roughness conditions. Depths to 10 feet were of primary interest in this project. Although further development is required, this project has demonstrated that GPR can be used to identify transitions between different sub-surface conditions, as in going from one rock type to another. Additionally, the average relative dielectric constant of the material can be estimated which can be used to help identify the material. This information can be used to characterize an excavation site for use in budgeting a job. A real-time GPR would provide the operator with sub-surface images that could help with setting the optimum feed and speed rates of the trenching machine
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