1,299 research outputs found
The Blackhole-Dark Matter Halo Connection
We explore the connection between the central supermassive blackholes (SMBH)
in galaxies and the dark matter halo through the relation between the masses of
the SMBHs and the maximum circular velocities of the host galaxies, as well as
the relationship between stellar velocity dispersion of the spheroidal
component and the circular velocity. Our assumption here is that the circular
velocity is a proxy for the mass of the dark matter halo. We rely on a
heterogeneous sample containing galaxies of all types. The only requirement is
that the galaxy has a direct measurement of the mass of its SMBH and a direct
measurement of its circular velocity and its velocity dispersion. Previous
studies have analyzed the connection between the SMBH and dark matter halo
through the relationship between the circular velocity and the bulge velocity
dispersion, with the assumption that the bulge velocity dispersion stands in
for the mass of the SMBH, via the well{}-established SMBH mass{}-bulge velocity
dispersion relation. Using intermediate relations may be misleading when one is
studying them to decipher the active ingredients of galaxy formation and
evolution. We believe that our approach will provide a more direct probe of the
SMBH and the dark matter halo connection. We find that the correlation between
the mass of supermassive blackholes and the circular velocities of the host
galaxies is extremely weak, leading us to state the dark matter halo may not
play a major role in regulating the blackhole growth in the present Universe.Comment: Accepted for publication in the Ap
Transfer and Development Length of Prestressing Tendons in Full-Scale AASHTO Prestressed Concrete Girders Using Self-Consolidating Concrete
Self-consolidating concrete (SCC) is a highly workable concrete that flows through densely reinforced or
complex structural elements under its own weight. The benefits of using SCC include: a) Reducing labor costs
by eliminating the need for mechanical vibration, b) Improving constructability, c) Providing a virtually flawless
finish, d) Providing uniform and homogenous concrete, and e) Easily filling a complex shape formwork. Even
though SCC is comparable to conventional concrete in terms of strength, the comparability of its bond to steel is
less well-defined. This disparity of knowledge becomes more critical when using SCC in prestressed members
due to the impact that bond strength has on the transfer and development lengths of prestressing tendons.
The increasing interest among Illinois precasters in using SCC in bridge girders has motivated the Illinois
Department of Transportation (IDOT) and the Illinois Center for Transportation (ICT) to sponsor this synthesis
study, which reviews and combines information from literature discussing the impact of using SCC on the
transfer and development lengths of prestressing tendons in AASHTO bridge girders. The primary objectives of
this study include: (1) Utilizing the results of previous research to evaluate the effect of using SCC on the
transfer and development lengths of prestressing tendons and evaluate how SCC compares with conventional
concrete, (2) Investigating the feasibility of using SCC in AASHTO bridge girders without the need for changing
current design provisions recommended by the ACI and AASHTO, and (3) Providing IDOT with
recommendations regarding the application of SCC in prestressed bridge girders.
17. KeyICT-R27-36published or submitted for publicationis peer reviewe
Energy Efficiency Prediction using Artificial Neural Network
Buildings energy consumption is growing gradually and put away around 40% of total energy use. Predicting heating and cooling loads of a building in the initial phase of the design to find out optimal solutions amongst different designs is very important, as ell as in the operating phase after the building has been finished for efficient energy. In this study, an artificial neural network model was designed and developed for predicting heating and cooling loads of a building based on a dataset for building energy performance. The main factors for input variables are: relative compactness, roof area, overall height, surface area, glazing are a, wall area, glazing area distribution of a building, orientation, and the output variables: heating and cooling loads of the building. The dataset used for training are the data published in the literature for various 768 residential buildings. The model was trained and validated, most important factors affecting heating load and cooling load are identified, and the accuracy for the validation was 99.60%
The Nature of the UV/X-Ray Absorber in PG 2302+029
We present Chandra X-ray observations of the radio-quiet QSO PG 2302+029.
This quasar has a rare system of ultra-high velocity (-56,000 km/s) UV
absorption lines that form in an outflow from the active nucleus (Jannuzi et
al. 2003). The Chandra data indicate that soft X-ray absorption is also
present. We perform a joint UV and X-ray analysis, using photoionization
calculations, to detemine the nature of the absorbing gas. The UV and X-ray
datasets were not obtained simultaneously. Nonetheless, our analysis suggests
that the X-ray absorption occurs at high velocities in the same general region
as the UV absorber. There are not enough constraints to rule out multi-zone
models. In fact, the distinct broad and narrow UV line profiles clearly
indicate that multiple zones are present. Our preferred estimates of the
ionization and total column density in the X-ray absorber (log U=1.6,
N_H=10^22.4 cm^-2) over predict the O VI 1032, 1038 absorption unless the X-ray
absorber is also outflowing at ~56,000 km/s, but they over predict the Ne VIII
770, 780 absorption at all velocities. If we assume that the X-ray absorbing
gas is outflowing at the same velocity of the UV-absorbing wind and that the
wind is radiatively accelerated, then the outflow must be launched at a radius
of < 10^15 cm from the central continuum source. The smallness of this radius
casts doubts on the assumption of radiative acceleration.Comment: Accepted for Publication in Ap
Handwritten Signature Verification using Deep Learning
Every person has his/her own unique signature that is used mainly for the purposes of personal
identification and verification of important documents or legal transactions. There are two kinds of signature
verification: static and dynamic. Static(off-line) verification is the process of verifying an electronic or document
signature after it has been made, while dynamic(on-line) verification takes place as a person creates his/her
signature on a digital tablet or a similar device. Offline signature verification is not efficient and slow for a large
number of documents. To overcome the drawbacks of offline signature verification, we have seen a growth in
online biometric personal verification such as fingerprints, eye scan etc. In this paper we created CNN model
using python for offline signature and after training and validating, the accuracy of testing was 99.70%
Treatment of metastatic spinal lesions with a navigational bipolar radiofrequency ablation device: A multicenter retrospective study
- …
