1,901 research outputs found
SAE Small Vehicle Lifts
The SAE (Society for Automotive Engineers) vehicle teams at Cal Poly need an easy way to access the undersides of their vehicles to facilitate maintenance and servicing. The purpose of this project was to provide a solution that could lift the vehicles effectively and safely from above so that the underside of the vehicles can be accessed, as well as elevating the vehicles to an ergonomic working height. Design specifications were determined based off each vehicle’s requirements in addition to what the team intends to do with their suspended vehicle. After several concept iterations, the team decided to purchase an engine hoist and replace the hydraulic cylinder with a fixed tube and construct a custom transmission thereby turning the engine hoist into a crane mechanism that can be operated easily without concerns of reliability. The team constructed a total of three lifts, each with different specifications, for the Baja, Formula, and F2000 cars. Material testing was done to verify that the unknown material of the purchased lifts was strong enough to support the loading, as well as final load testing by lifting a vehicle to its designed height
Regge Calculus in Teleparallel Gravity
In the context of the teleparallel equivalent of general relativity, the
Weitzenbock manifold is considered as the limit of a suitable sequence of
discrete lattices composed of an increasing number of smaller an smaller
simplices, where the interior of each simplex (Delaunay lattice) is assumed to
be flat. The link lengths between any pair of vertices serve as independent
variables, so that torsion turns out to be localized in the two dimensional
hypersurfaces (dislocation triangle, or hinge) of the lattice. Assuming that a
vector undergoes a dislocation in relation to its initial position as it is
parallel transported along the perimeter of the dual lattice (Voronoi polygon),
we obtain the discrete analogue of the teleparallel action, as well as the
corresponding simplicial vacuum field equations.Comment: Latex, 10 pages, 2 eps figures, to appear in Class. Quant. Gra
Close Pairs as Proxies for Galaxy Cluster Mergers
Galaxy cluster merger statistics are an important component in understanding
the formation of large-scale structure. Unfortunately, it is difficult to study
merger properties and evolution directly because the identification of cluster
mergers in observations is problematic. We use large N-body simulations to
study the statistical properties of massive halo mergers, specifically
investigating the utility of close halo pairs as proxies for mergers. We
examine the relationship between pairs and mergers for a wide range of merger
timescales, halo masses, and redshifts (0<z<1). We also quantify the utility of
pairs in measuring merger bias. While pairs at very small separations will
reliably merge, these constitute a small fraction of the total merger
population. Thus, pairs do not provide a reliable direct proxy to the total
merger population. We do find an intriguing universality in the relation
between close pairs and mergers, which in principle could allow for an estimate
of the statistical merger rate from the pair fraction within a scaled
separation, but including the effects of redshift space distortions strongly
degrades this relation. We find similar behavior for galaxy-mass halos, making
our results applicable to field galaxy mergers at high redshift. We investigate
how the halo merger rate can be statistically described by the halo mass
function via the merger kernel (coagulation), finding an interesting
environmental dependence of merging: halos within the mass resolution of our
simulations merge less efficiently in overdense environments. Specifically,
halo pairs with separations less than a few Mpc/h are more likely to merge in
underdense environments; at larger separations, pairs are more likely to merge
in overdense environments.Comment: 12 pages, 9 figures; Accepted for publication in ApJ. Significant
additions to text and two figures changed. Added new findings on the
universality of pair mergers and added analysis of the effect of FoF linking
length on halo merger
The Clustering of Massive Halos
The clustering properties of dark matter halos are a firm prediction of
modern theories of structure formation. We use two large volume,
high-resolution N-body simulations to study how the correlation function of
massive dark matter halos depends upon their mass and formation history. We
find that halos with the lowest concentrations are presently more clustered
than those of higher concentration, the size of the effect increasing with halo
mass; this agrees with trends found in studies of lower mass halos. The
clustering dependence on other characterizations of the full mass accretion
history appears weaker than the effect with concentration. Using the integrated
correlation function, marked correlation functions, and a power-law fit to the
correlation function, we find evidence that halos which have recently undergone
a major merger or a large mass gain have slightly enhanced clustering relative
to a randomly chosen population with the same mass distribution.Comment: 10 pages, 8 figures; text improved, references and one figure added;
accepted for publication in Ap
Hillslope and stream connectivity: simulation of concentration-discharge patterns using the HYDRUS model
Abstract: Nutrient concentrations and loads in streamflow are sensitive to rapidly changing stream chemistry and discharge during storms. Mechanistic models that can simulate water and solute movement at hillslope scales could be useful for predicting concentration-discharge (C-Q) patterns and thereby improve our quantitative understanding of terrestrial-aquatic linkages for targeted catchment management. Our objective was to use the HYDRUS model to represent hydro-biogeochemical processes in soils that drive seepage of water and solutes from soil profiles into streams. Specifically we compared measurements in the literature with HYDRUS outputs using two methods for simulating runoff. This model predicts runoff (R) as rainfall that is instantaneously in excess of infiltration, but it is not designed to route runoff as overland flow. Post-HYDRUS addition of seepage to runoff was used to simulate the delivery of dissolved or particulate constituents to a stream (method A). Alternatively, we demonstrated how simulations using HYDRUS could include a hypothetical layer at the top of the soil profile with extremely high porosity and hydraulic conductivity that enabled overland flow and down-slope infiltration, but in this case only dissolved constituents could be considered (method B). These methods were evaluated by comparing the simulated temporal patterns of discharge and concentration with observed patterns. The catchments considered were in Slovenia (4210 ha) and in Australia (11.9 ha). Methods A and B were shown to adequately simulate some aspects of published discharge-concentration patterns, e.g. runoff dilution or concentration effects, but the temporal patterns of discharge for both methods did not precisely match those measured at small time-steps (e.g. 15 minutes). This limitation was due mainly to inadequate simulation of the down-slope movement of runoff and down-slope infiltration of a portion of this runoff. Method A was generally more useful than method B. Despite this limitation, both methods, if used carefully, should be adequate for many purposes, especially when simulating longer time-steps. Additional hypothetical simulations illustrated the significance of soil hydraulic conductivity, soil water content, and vertical gradients in solute concentrations in soil. Two temporal types of dischargeconcentration patterns were observed; short-term hysteresis caused by runoff during and shortly after a rainfall event, and longer-term trends associated with infiltration and seepage. Clockwise and anti-clockwise hysteresis was demonstrated to be potentially due to the temporal asynchrony of peak discharge and peak concentration in runoff. Simulations also demonstrated advantages over using the more common approach of a 2-or 3-component mixing model. Our results suggest that the HYDRUS model will be useful for the mechanistic simulation of within-soil processes that are needed to predict discharge-concentration patterns at hillslope scales
Efficacy and Safety of Biosimilar FYB201 Compared with Ranibizumab in Neovascular Age-Related Macular Degeneration.
Abstract Purpose This trial was conducted to investigate the clinical equivalence of the proposed biosimilar FYB201 and reference ranibizumab in patients with treatment-naive, subfoveal choroidal neovascularization caused by neovascular age-related macular degeneration (nAMD). Design This was a prospective, multicenter, evaluation-masked, parallel-group, 48-week, phase III randomized study. Participants A total of 477 patients were randomly assigned to receive FYB201 (n = 238) or reference ranibizumab (n = 239). Methods Patients received FYB201 or ranibizumab 0.5 mg by intravitreal injection in the study eye every four weeks. Main Outcome Measures The primary end point was change from baseline in best corrected visual acuity (BCVA) by Early Treatment Diabetic Retinopathy Study (ETDRS) letters at 8 weeks prior to the third monthly intravitreal injection. Biosimilarity of FYB201 to its originator was assessed via a two-sided equivalence test, with an equivalence margin in BCVA of 3 ETDRS letters. Results BCVA improved in both groups, with a mean improvement of +5.1 (FYB201) and +5.6 (reference ranibizumab) ETDRS letters at week 8. The analysis of covariance (ANCOVA) least squares mean difference for the change from baseline between FYB201 and reference ranibizumab was –0.4 ETDRS letters with a 90% confidence interval (CI) of –1.6 to 0.9. Primary end point was met as the 90% CI was within the predefined equivalence margin. Adverse events were comparable between treatment groups. Conclusions FYB201 is biosimilar to reference ranibizumab in terms of clinical efficacy and ocular and systemic safety in the treatment of patients with nAMD
Gauge theory of disclinations on fluctuating elastic surfaces
A variant of a gauge theory is formulated to describe disclinations on
Riemannian surfaces that may change both the Gaussian (intrinsic) and mean
(extrinsic) curvatures, which implies that both internal strains and a location
of the surface in R^3 may vary. Besides, originally distributed disclinations
are taken into account. For the flat surface, an extended variant of the
Edelen-Kadic gauge theory is obtained. Within the linear scheme our model
recovers the von Karman equations for membranes, with a disclination-induced
source being generated by gauge fields. For a single disclination on an
arbitrary elastic surface a covariant generalization of the von Karman
equations is derived.Comment: 13 page
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. V. Rising X-ray Emission from an Off-Axis Jet
We report the discovery of rising X-ray emission from the binary neutron star
(BNS) merger event GW170817. This is the first detection of X-ray emission from
a gravitational-wave source. Observations acquired with the Chandra X-ray
Observatory (CXO) at t~2.3 days post merger reveal no significant emission,
with L_x<=3.2x10^38 erg/s (isotropic-equivalent). Continued monitoring revealed
the presence of an X-ray source that brightened with time, reaching L_x\sim
9x10^39 erg/s at ~15.1 days post merger. We interpret these findings in the
context of isotropic and collimated relativistic outflows (both on- and
off-axis). We find that the broad-band X-ray to radio observations are
consistent with emission from a relativistic jet with kinetic energy
E_k~10^49-10^50 erg, viewed off-axis with theta_obs~ 20-40 deg. Our models
favor a circumbinary density n~ 0.0001-0.01 cm-3, depending on the value of the
microphysical parameter epsilon_B=10^{-4}-10^{-2}. A central-engine origin of
the X-ray emission is unlikely. Future X-ray observations at
days, when the target will be observable again with the CXO, will provide
additional constraints to solve the model degeneracies and test our
predictions. Our inferences on theta_obs are testable with gravitational wave
information on GW170817 from Advanced LIGO/Virgo on the binary inclination.Comment: 7 Pages, 4 Figures, ApJL, In Press. Keywords: GW170817, LV
Potencial de aproveitamento de resĂduos agroindustriais atravĂ©s da minhocultura.
bitstream/item/106185/1/Boletim-180-web.pd
A Theoretical Framework for Rural Knowledge Centers
Exponential growth in ICTs (Information and Communication Technologies) and establishment of RKCs (Rural
Knowledge Centers) have been fast spreading across the globe. In the continuous process, there are tens of
thousands of RKCs are being established by various agencies, to provide shared public access to ICTs for meeting
educational, social, personal, economic and entertainment needs of the rural community. As most of these
initiatives are relatively new, there are mixed opinions on the social and economic impacts of RKCs. There is also
lack of good understanding on the conceptual and theoretical framework for planning and designing of RKCs. The
authors conducted a study to fill this information gap by assessing selected ICT4D (ICT for development) project
sites in rural India. Through the systemic analysis of the data and continuous interpretation of the observations, the
study proposes a framework for planning and designing of RKCs. In this paper, the authors present the study
results, and discuss the evolution process of RKCs and factors that influences planning and designing of RKCs
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