13,466 research outputs found
Investigation of the effects of Extra Vehicular Activity (EVA) and Launch and Entry (LES) gloves on performance
Human capabilities such as dexterity, manipulability, and tactile perception are unique and render the hand as a very versatile, effective and a multipurpose tool. This is especially true for unknown environments such as the EVA environment. In the microgravity environment interfaces, procedures, and activities are too complex, diverse, and defy advance definition. Under these conditions the hand becomes the primary means of locomotion, restraint, and material handling. Facilitation of these activities, with simultaneous protection from the cruel EVA environment are the two, often conflicting, objectives of glove design. The objectives of this study was (1) to assess the effects of EVA gloves at different pressures on human hand capabilities, (2) to devise a protocol for evaluating EVA gloves, (3) to develop force time relations for a number of EVA glove pressure combinations, and (4) to evaluate two types of launch and entry suit gloves. The objectives were achieved through three experiments. The experiments for achieving objectives 1, 2, and 3 were performed in the glove box in building 34. In experiment 1 three types of EVA gloves were tested at five pressure differentials. A number of performance measures were recorded. In experiment 2 the same gloves as in experiment 1 were evaluated in a reduced number of pressure conditions. The performance measure was endurance time. Six subjects participated in both the experiments. In experiment 3 two types of launch and entry suit gloves were evaluated using a paradigm similar to experiment 1. Currently the data is being analyzed. However for this report some summary analyses have been performed. The results indicate that a) With EVA gloves strength is reduced by nearly 50 percent, b) performance decrements increase with increasing pressure differential, c) TMG effects are not consistent across the three gloves tested, d) some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand, and e) differences in performance exist between partial pressure suit glove and full pressure suit glove, especially in the unpressurized condition
Arithmetic Progressions in a Unique Factorization Domain
Pillai showed that any sequence of consecutive integers with at most 16 terms
possesses one term that is relatively prime to all the others. We give a new
proof of a slight generalization of this result to arithmetic progressions of
integers and further extend it to arithmetic progressions in unique
factorization domains of characteristic zero.Comment: Version 2 (to appear in Acta Arithmetica) with minor typos correcte
UBVRI CCD photometry of the OB associations Bochum 1 and Bochum 6
We report the first deep CCD photometry of 2460 stars in the field of
two poorly studied OB associations Bochum 1 and Bochum 6. We selected 15 and 14
probable members in Bochum 1 and Bochum 6 respectively using photometric
criteria and proper motion data of Tycho 2. Our analysis indicates variable
reddening having mean value of 0.470.10 and 0.710.13 mag
for Bochum 1 and Bochum 6 respectively. Using the zero-age main-sequence
fitting method, we derive a distance of 2.80.4 and 2.50.4 Kpc for
Bochum 1 and Bochum 6 respectively. We obtain an age of 105 Myrs for both
the associations from isochrone fitting. In both associations high and low mass
stars have probably formed together. Within the observational uncertainties,
mass spectrum of the both associations appears to be similar to the Salpeter's
one.Comment: 14 pages, 7 figures, 6 tables. Accepted for Bull. Astr. Soc. Indi
Non-uniform extinction in young open star clusters
The extinction law and the variation of colour excess with position,
luminosity as well as spectral class in young open star clusters NGC 663,
NGC869, NGC 884, NGC 1502, NGC 1893, NGC 2244, NGC 2264, NGC 6611, Tr 14, Tr
15,Tr 16, Coll 228, Tr 37 and Be 86 have been studied. The difference in the
minimum and maximum values of E(B-V) of cluster members has been considered as
a measure of the presence of non-uniform gas and dust inside the clusters. Its
value ranges from 0.22 to 1.03 mag in clusters under study, which indicates
that non-uniform extinction is present in all the clusters. It has been noticed
for the first time in NGC 1502 and Tr 37. It is also found that the
differential colour excess in open clusters, which may be due to the presence
of gas and dust, decreases systematically with the age of clusters indicating
that matter is used either in star formation or blown away by hot stars or
both. There is no uniformity in the variation of E(B-V) with either position or
spectral class or luminosity.Comment: 11 pages, 8 figures, 4 tables; accepted for publication in MNRAS,
typos adde
Effect of Irrigation and Potash Levels on Keeping Quality of Potato
Irrigation and fertilizer are the most dominating factors, in deciding the keeping quality of potato. It is, therefore, essential to formulate the efficient, reliable and economically viable irrigation management strategy with the use of potassium nutrient in order to produce better keeping quality. The investigation comprising four levels of irrigation (25, 30, 35 and 40 mm CPE (Cumulative pan evaporation) and four levels of potash (0, 100, 125 and 150 kg/ha) was carried out at Research Farm of the Department of Vegetable Science, CCS Haryana Agricultural University, (Haryana) Hisar, India during two years to find out the optimum level of irrigation and potash for obtaining higher yield of potatoes with better keeping quality at ambient room temperature. The potato variety used for the investigation was Kufri Bahar. The treatments were laid out in a split plot design with three replications. The increasing levels of irrigation and potash showed significant improvement in keeping quality parameters of potato. Likewise, the values for physiological loss in weight and decay loss of potato tubers (%) at 15, 30, 45 and 60 days after harvest were the lowest with irrigation level 40 mm CPE and application of potash @ 150 kg/ha. The two years results suggest that the irrigation level 40 mm CPE along with potash @ 150 kg/ha has shown the best treatment combination for the storage of potato at ambient room temperature under semiarid conditions of Hisar (Haryana)
Moving from Data-Constrained to Data-Enabled Research: Experiences and Challenges in Collecting, Validating and Analyzing Large-Scale e-Commerce Data
Widespread e-commerce activity on the Internet has led to new opportunities
to collect vast amounts of micro-level market and nonmarket data. In this paper
we share our experiences in collecting, validating, storing and analyzing large
Internet-based data sets in the area of online auctions, music file sharing and
online retailer pricing. We demonstrate how such data can advance knowledge by
facilitating sharper and more extensive tests of existing theories and by
offering observational underpinnings for the development of new theories. Just
as experimental economics pushed the frontiers of economic thought by enabling
the testing of numerous theories of economic behavior in the environment of a
controlled laboratory, we believe that observing, often over extended periods
of time, real-world agents participating in market and nonmarket activity on
the Internet can lead us to develop and test a variety of new theories.
Internet data gathering is not controlled experimentation. We cannot randomly
assign participants to treatments or determine event orderings. Internet data
gathering does offer potentially large data sets with repeated observation of
individual choices and action. In addition, the automated data collection holds
promise for greatly reduced cost per observation. Our methods rely on
technological advances in automated data collection agents. Significant
challenges remain in developing appropriate sampling techniques integrating
data from heterogeneous sources in a variety of formats, constructing
generalizable processes and understanding legal constraints. Despite these
challenges, the early evidence from those who have harvested and analyzed large
amounts of e-commerce data points toward a significant leap in our ability to
understand the functioning of electronic commerce.Comment: Published at http://dx.doi.org/10.1214/088342306000000231 in the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org
DeepFuse: A Deep Unsupervised Approach for Exposure Fusion with Extreme Exposure Image Pairs
We present a novel deep learning architecture for fusing static
multi-exposure images. Current multi-exposure fusion (MEF) approaches use
hand-crafted features to fuse input sequence. However, the weak hand-crafted
representations are not robust to varying input conditions. Moreover, they
perform poorly for extreme exposure image pairs. Thus, it is highly desirable
to have a method that is robust to varying input conditions and capable of
handling extreme exposure without artifacts. Deep representations have known to
be robust to input conditions and have shown phenomenal performance in a
supervised setting. However, the stumbling block in using deep learning for MEF
was the lack of sufficient training data and an oracle to provide the
ground-truth for supervision. To address the above issues, we have gathered a
large dataset of multi-exposure image stacks for training and to circumvent the
need for ground truth images, we propose an unsupervised deep learning
framework for MEF utilizing a no-reference quality metric as loss function. The
proposed approach uses a novel CNN architecture trained to learn the fusion
operation without reference ground truth image. The model fuses a set of common
low level features extracted from each image to generate artifact-free
perceptually pleasing results. We perform extensive quantitative and
qualitative evaluation and show that the proposed technique outperforms
existing state-of-the-art approaches for a variety of natural images.Comment: ICCV 201
The Stellar Initial Mass Function at the Epoch of Reionization
I provide estimates of the ultraviolet and visible light luminosity density
at z~6 after accounting for the contribution from faint galaxies below the
detection limit of deep Hubble and Spitzer surveys. I find the rest-frame
V-band luminosity density is a factor of ~2-3 below the ultraviolet luminosity
density at z~6. This implies that the maximal age of the stellar population at
z~6, for a Salpeter initial mass function, and a single, passively evolving
burst, must be <100 Myr. If the stars in z~6 galaxies are remnants of the
star-formation that was responsible for ionizing the intergalactic medium,
reionization must have been a brief process that was completed at z<7. This
assumes the most current estimates of the clumping factor and escape fraction
and a Salpeter slope extending up to 200 M_{\sun} for the stellar initial mass
function (IMF; dN/dM \propto M^{\alpha}, \alpha=-2.3). Unless the ratio of the
clumping factor to escape fraction is less than 60, a Salpeter slope for the
stellar IMF and reionization redshift higher than 7 is ruled out. In order to
maintain an ionized intergalactic medium from redshift 9 onwards, the stellar
IMF must have a slope of \alpha=-1.65 even if stars as massive as ~200 M_{\sun}
are formed. Correspondingly, if the intergalactic medium was ionized from
redshift 11 onwards, the IMF must have \alpha~-1.5. The range of stellar mass
densities at z~6 straddled by IMFs which result in reionization at z>7 is
1.3+/-0.4\times10^{7} Msun/Mpc^3.Comment: 25 pages, 2 tables, 6 figures, ApJ, in press, v680 n
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