2,262 research outputs found
Space-Based Thermal Infrared Studies of Asteroids
Large-area surveys operating at mid-infrared wavelengths have proven to be a
valuable means of discovering and characterizing minor planets. Through the use
of radiometric models, it is possible to derive physical properties such as
diameters, albedos, and thermal inertia for large numbers of objects. Modern
detector array technology has resulted in a significant improvement in spatial
resolution and sensitivity compared with previous generations of space-based
infrared telescopes, giving rise to a commensurate increase in the number of
objects that have been observed at these wavelengths. Space-based infrared
surveys of asteroids therefore offer an effective means of rapidly gathering
information about small body populations' orbital and physical properties. The
AKARI, WISE/NEOWISE, Spitzer, and Herschel missions have significantly
increased the number of minor planets with well-determined diameters and
albedos.Comment: Chapter for Asteroids IV book (accepted for publication
Aerodynamic investigation of an air-cooled axial-flow turbine. Part 2: Rotor blade tip-clearance effects on overall turbine performance and internal gas flow conditions: Experimental results and prediction methods
Total turbine blade performance was investigated while changing the blade tip clearance in three ways. The internal flow at the moving blade outlet point was measured. Experimental results were compared with various theoretical methods. Increased blade clearance leads to decreased turbine efficiency
Pupillometry, a bioengineering overview
The pupillary control system is examined using a microprocessor based integrative pupillometer. The real time software functions of the microprocessor include: data collection, stimulus generation and area to diameter conversion. Results of an analysis of linear and nonlinear phenomena are presented
EFFECT OF COAL UPGRADING ON RHEOLOGY OF COAL WATER MIXTURE
Coal water mixture (CWM) is coal-water slurry in which particles of coal with a certain particle size distribution are suspended in water. CWM is required to have the highest possible coal concentration and a moderate viscosity in order to make handling easy. The main purpose of this study is to obtain the effect of coal upgrading on the rheology of CWM in terms of finding the most suitable dispersing additive in producing CWM with highest coal concentration. Two kinds of coal, raw and upgraded coal, from three areas in Indonesia have been used. Three kinds dispersing additives, i.e. formalin conden- sation product of naphthalene sulfuric acid (NSF), polystyrene sulfonic acid (PSS) and poly (meth) acrylate (PMA) were tested to produce CWM with good flow characteristics. The rheology of CWM was prepared, measured by a stress control type rheometer (Rheometric Scientific Co. Ltd., SR-5) in steady shear mode at 25ºC. The apparent viscosity of upgraded coals showed a better slurry-ability of CWM as a function of coal concentration for every dispersing additive compared to the raw coal
THE EFFECT OF DISPERSING AND STABILIZING ADDITIVE ON THE STABILITY OF UPGRADED COAL WATER MIXTURE
The upgraded brown coal water mixture (UBCWM) stability with several dispersing and stabilizing additives was studied based on coal sedimentation time history. UBCWM was filled up in a settling column; which has four holes in the upper, upper middle, bottom middle and middle side to take samples. Results indicate that the addition of Naphthalene sulfonate formaldehyde condensate (NSF) as dispersant together with S-194 some kinds of bio polysacharide with long branches produced by Dainippon Pharmaceutical Co. Ltd. as stabilizer, produces UBCWM with the best stability compare with that by using polystyrene sulfonate (PSS) and polymethacrylate (PMA) together with carboxyl methyl cellulose (CMC) and S-60 also some kinds of bio polysacharide, but without branches pro- duced by Dainippon Pharmaceutical Co. Ltd . Even the addition of S-194 results UBCWM with good stability, from the economical point of view, the addition of S-194 is a problem. The price of S-194 is expensive, whereas CMC is abundant and cheap. Therefore, the use of CMC as stabilizing additive was also effective in preparing stable UBCWM according to the stability of the UBCWM by using S- 194 and CMC is not significantly different
Photometric Observations of Star Formation Activity in Early Type Spirals
We observationally study the current star formation activities of early type
spiral galaxies. We construct a complete sample of 15 early type spirals having
far-infrared (FIR) to optical B band luminosity ratios, L(FIR)/L(B), larger
than the average of the type, and make their CCD imaging of the R and H-alpha
bands. The equivalent widths of H-alpha emission increase with increasing
L(FIR)/L(B), indicating that L(FIR)/L(B) can be an indicator of star formation
for such early type spirals with star formation activities higher than the
average. For all of the observed early type spirals, the extended HII regions
exist at the central regions with some asymmetric features. H-alpha emission is
more concentrated to the galactic center than the R band light, and the degree
of the concentration increases with the star formation activity. We also
analyze the relation between the star formation activities and the existence of
companion galaxies in the sample galaxies and other bright early type spirals.
No correlation is found and this suggests that the interaction is not
responsible for all of the star formation activities of early type spirals.Comment: LaTex, 23 pages (2 tables included), plus 9 Postscript figures & 1
table. To be published in AJ (November issue
CHEMICAL AND PHYSICAL PROPERTIES OF UPGRADED BROWN COAL
Results of proximate analyses indicate that inherent moisture of the upgraded coals decrease signifi- cantly compared to that of the raw coals. Hence, the calorific value of the upgraded coals increases. The ash content of the upgraded coals did not change obviously due to the UBC process which was conducted at low temperature. However, the volatile matter content increase slightly due to the residue plugs over coal pores to prevent re-absorb of moisture. From ultimate analyses, carbon content of the upgraded coals increases, whereas the hydrogen and oxygen contents decrease. The UBC process hardly effects to the sulfur and nitrogen contents. The equilibrium moisture of the upgraded coals was determined by using ASTM Standard method, most of them were less than 9%. The functional group of C-H and C=O of the upgraded coals were slightly less than that of the raw coals. The aromaticity of coal, all of the upgraded coals was increase. The petrography of both the raw and the upgraded coals indicates that the mean vitrinite reflectance was slightly higher in the upgraded coal compared to that of the raw coal. There was no significant quantity and textural differences of maceral in both coals. The specific surface area of the upgraded coals was lower than that of the raw coals due to the plugging of pore structure and shrinkage by residual oil addition. The briquettability of Upgraded coal briquette according to drop shatter test and compressive strength indicates good characteristics of briquette
Boson-fermion mappings for odd systems from supercoherent states
We extend the formalism whereby boson mappings can be derived from
generalized coherent states to boson-fermion mappings for systems with an odd
number of fermions. This is accomplished by constructing supercoherent states
in terms of both complex and Grassmann variables. In addition to a known
mapping for the full so(2+1) algebra, we also uncover some other formal
mappings, together with mappings relevant to collective subspaces.Comment: 40 pages, REVTE
First-principles study on the origin of large thermopower in hole-doped LaRhO3 and CuRhO2
Based on first-principles calculations, we study the origin of the large
thermopower in Ni-doped LaRhO3 and Mg-doped CuRhO2. We calculate the band
structure and construct the maximally localized Wannier functions from which a
tight binding Hamiltonian is obtained. The Seebeck coefficient is calculated
within the Boltzmann's equation approach using this effective Hamiltonian. For
LaRhO3, we find that the Seebeck coefficient remains nearly constant within a
large hole concentration range, which is consistent with the experimental
observation. For CuRhO2, the overall temperature dependence of the calculated
Seebeck coefficient is in excellent agreement with the experiment. The origin
of the large thermopower is discussed.Comment: 7 pages, to be published J. Phys.: Cond. Matt., Proc. QSD 200
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