4,453 research outputs found
Some system considerations in configuring a digital flight control - navigation system
A trade study was conducted with the objective of providing a technical guideline for selection of the most appropriate computer technology for the automatic flight control system of a civil subsonic jet transport. The trade study considers aspects of using either an analog, incremental type special purpose computer or a general purpose computer to perform critical autopilot computation functions. It also considers aspects of integration of noncritical autopilot and autothrottle modes into the computer performing the critical autoland functions, as compared to the federation of the noncritical modes into either a separate computer or with a R-Nav computer. The study is accomplished by establishing the relative advantages and/or risks associated with each of the computer configurations
Personality Characteristics and Labour Market Entry an exploration
In an explorative study, the value of four personality constructs in predicting success in the labour market entry has been analysed with a sample of graduates in economics from Maastricht University. The research question is: do personality characteristics predict labour market entry success and how much weight do these âsoftâ factors have compared to the traditional âhardâ human capital factors like study results? Two out of the four constructs, i.e. (internal) Locus of control and Type A behaviour appear to have a positive effect on labour market success. The effects are independent of the effects of study results and other traditional human capital variables. Locus of control affects getting a job soon after graduation and having tenure, whereas Type A behaviour affects having tenure and wages. Study results merely affect job quality indicators. For obtaining an academic job, the human capital factors have a positive effect while personality has no effect at all. The findings underline the relevance of further labour market research with respect to the importance and role of the so called âsoftâ factors like personality characteristics. At the same time, the role of âhardâ human capital factors is not to be neglected. Both types of factors seem to have their own and independent effects. Future research directions are given and implications of the study are discussed.labour market entry;
The Implications of Galaxy Formation Models for the TeV Observations of Current Detectors
This paper represents a step toward constraining galaxy formation models via
TeV gamm a ray observations. We use semi-analytic models of galaxy formation to
predict a spectral distribution for the intergalactic infrared photon field,
which in turn yields information about the absorption of TeV gamma rays from
extra-galactic sources. By making predictions for integral flux observations at
>200 GeV for several known EGRE T sources, we directly compare our models with
current observational upper limits obtained by Whipple. In addition, our
predictions may offer a guide to the observing programs for the current
population of TeV gamma ray observatories.Comment: 6 pages, 11 figures, to appear in the proceedings of the 6th TeV
Workshop at Snowbird, U
Application of the techniques for evaluating the acoustic sources of background noise in wind tunnel facilities
Techniques for evaluating acoustic sources of background noise in wind tunnel
The Effects of CCA Preservative Treatment and Redrying on the Bending Properties of 2 X 6 Southern Pine Lumber
Southern pine dimension lumber (commercially graded No. 2 loblolly pine 2 x 6s) was treated with chromated copper arsenate (CCA) preservative (0.4 or 0.6 pcf) and then air-dried or kiln-dried (160, 190, or 240 F). CCA treatment significantly reduced average bending strength, but no discernible differences were found between controls and CCA-treated groups in the extreme lower portions (< 10th percentile) of the bending-strength distributions. When these same specimens were then considered solely on the basis of strength-reducing characteristics, there were obvious differences in how the CCA treatments and subsequent redrying affected these various strength-ratio grades of 2 x 6 lumber; higher grades appeared to be less affected than lower grades. Similar to the trend shown when commercially graded, the middle and upper portion of each strength-ratio grade bending-strength distribution than did drying at 240 F affected a broader range of the bending-srength distribution than did drying at 160 F. The broadened range of significant effects noted after high-temperature redrying indicates that posttreatment kiln-drying temperatures higher than 190 F should be avoided.The effects of CCA treatment and redrying were highly interactive with strength-ratio grade and the presence or absence of pith. CCA treatment reduced the strength of lumber containing pith and having a strength ratio of 0.65 and containing pith was not affected by CCA treatment. The magnitude of this pith-related interaction demands recognition
Carbon Free Boston: Transportation Technical Report
Part of a series of reports that includes:
Carbon Free Boston: Summary Report;
Carbon Free Boston: Social Equity Report;
Carbon Free Boston: Technical Summary;
Carbon Free Boston: Buildings Technical Report;
Carbon Free Boston: Waste Technical Report;
Carbon Free Boston: Energy Technical Report;
Carbon Free Boston: Offsets Technical ReportOVERVIEW:
Transportation connects Bostonâs workers, residents and tourists to their livelihoods, health care, education,
recreation, culture, and other aspects of life quality. In cities, transit access is a critical factor determining
upward mobility. Yet many urban transportation systems, including Bostonâs, underserve some populations
along one or more of those dimensions. Boston has the opportunity and means to expand mobility access to
all residents, and at the same time reduce GHG emissions from transportation. This requires the
transformation of the automobile-centric system that is fueled predominantly by gasoline and diesel fuel.
The near elimination of fossil fuelsâcombined with more transit, walking, and bikingâwill curtail air
pollution and crashes, and dramatically reduce the public health impact of transportation. The City embarks
on this transition from a position of strength. Boston is consistently ranked as one of the most walkable and
bikeable cities in the nation, and one in three commuters already take public transportation.
There are three general strategies to reaching a carbon-neutral transportation system:
âą Shift trips out of automobiles to transit, biking, and walking;1
âą Reduce automobile trips via land use planning that encourages denser development and affordable
housing in transit-rich neighborhoods;
âą Shift most automobiles, trucks, buses, and trains to zero-GHG electricity.
Even with Bostonâs strong transit foundation, a carbon-neutral transportation system requires a wholesale
change in Bostonâs transportation culture. Success depends on the intelligent adoption of new technologies,
influencing behavior with strong, equitable, and clearly articulated planning and investment, and effective
collaboration with state and regional partners.Published versio
EROs found behind lensing clusters: II.Empirical properties, classification, and SED modelling based on multi-wavelength observations
We study the properties and nature of extremely red galaxies (ERO, R-K>5.6)
found behind two lensing clusters and compare them with other known galaxy
populations. New HST/ACS observations, Spitzer IRAC and MIPS, and Chandra/ACIS
observations of the two lensing clusters Abell 1835 and AC114 contemplate our
earlier optical and near-IR observations and have been used to study extremely
red objects (EROs) in these deep fields. We have found 6 and 9 EROs in Abell
1835 and AC114. Several (7) of these objects are undetected up to the I and/or
z band, and are hence ``optical'' drop-out sources. The photometric redshifts
of most of our sources (80%) are z~0.7-1.5. According to simple colour-colour
diagrams the majority of our objects would be classified as hosting old stellar
populations. However, there are clear signs of dusty starbursts for several
among them. These objects correspond to the most extreme ones in R-K colour. We
estimate a surface density of (0.97+-0.31) arcmin-2 for EROs with (R-K>5.6) at
K<20.5. Among our 15 EROs 6 (40 %) also classify as distant red galaxies
(DRGs). 11 of 13 EROs with available IRAC photometry also fulfil the selection
criteria for IRAC selected EROs (IEROs) of Yan et al. (2004). SED modelling
shows that ~ 36 % of the IEROs in our sample are luminous or ultra-luminous
infrared galaxies ((U)LIRG). Some very red DRGs are found to be very dusty
starbursts, even (U)LIRGs, as also supported by their mid-IR photometry. No
indication for AGNs is found, although faint activity cannot be excluded for
all objects. From mid-IR and X-ray data 5 objects are clearly classified as
starbursts. The derived properties are quite similar to those of DRGs and
IEROs, except for 5 extreme objects in terms of colours, for which a very high
extinction (Av>3) is found.Comment: 20 pages, 10 figures, accepted for publication in A&
The first Frontier Fields cluster: 4.5{\mu}m excess in a z~8 galaxy candidate in Abell 2744
We present in this letter the first analysis of a z~8 galaxy candidate found
in the Hubble and Spitzer imaging data of Abell 2744, as part of the Hubble
Frontier Fields legacy program. We applied the most commonly-used methods to
select exceptionally high-z galaxies by combining non-detection and
color-criteria using seven HST bands. We used GALFIT on IRAC images for fitting
and subtracting contamination of bright nearby sources. The physical properties
have been inferred from SED-fitting using templates with and without nebular
emission. This letter is focussed on the brightest candidate we found
(m=26.2) over the 4.9 arcmin field of view covered by the WFC3.
It shows a non-detection in the ACS bands and at 3.6{\mu}m whereas it is
clearly detected at 4.5{\mu}m with rather similar depths. This break in the
IRAC data could be explained by strong [OIII]+H{\beta} lines at z~8 which
contribute to the 4.5{\mu}m photometry. The best photo-z is found at
z~8.0, although solutions at low-redshift (z~1.9) cannot be
completely excluded, but they are strongly disfavoured by the SED-fitting work.
The amplification factor is relatively small at {\mu}=1.490.02. The Star
Formation Rate in this object is ranging from 8 to 60 Mo/yr, the stellar mass
is in the order of M=(2.5-10) x 10Mo and the size is
r~0.350.15 kpc. This object is one of the first z~8 LBG candidates showing
a clear break between 3.6{\mu}m and 4.5{\mu}m which is consistent with the IRAC
properties of the first spectroscopically confirmed galaxy at a similar
redshift. Due to its brightness, the redshift of this object could potentially
be confirmed by near infrared spectroscopy with current 8-10m telescopes. The
nature of this candidate will be revealed in the coming months with the arrival
of new ACS and Spitzer data, increasing the depth at optical and near-IR
wavelengths.Comment: 4 pages, 2 figures, Accepted for publication in Astronomy and
Astrophysics Letter
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