23 research outputs found
Adding Vision to a Quadrotor: A Design-Build-Test Adventure
Quadrotors are small and exceptionally agile vehicles with maneuverability that permits both indoor and outdoor flight. The vast majority of quadrotors are flown autonomously as drones or remotely by a human-operator. Applications of quadrotors range from commercial deliveries, to military and law reconnaissance as well as research tools for various fields. Our lab at Western Kentucky University built a quadrotor in 2013, and we have been exploring various modifications to refine its performance and various applications in which it could be productively employed. Recently, research has focused on the addition of a camera to add capabilities for first person view (FPV) piloting, photogrammetry, and real-time visual inspection.
The new camera system was to be designed, built, and tested as part of a Faculty-Undergraduate Student Engagement (FUSE) grant. The system consists of a gimbal with pan/tilt capabilities has been designed and built via a Stratasys rapid prototyping machine
The camera mount has met not only sizing and weight requirements, but also video transmission, recording, and live-viewing requirements. The design process has been successful in developing a pan/tilt camera mount for our lab’s quadrotor, and in creating countless learning outcomes as it produced multiple areas of research involving a variety of students with differing interests
Where do "red and dead" early-type void galaxies come from?
Void regions of the Universe offer a special environment for studying
cosmology and galaxy formation, which may expose weaknesses in our
understanding of these phenomena. Although galaxies in voids are observed to be
predominately gas rich, star forming and blue, a sub-population of bright red
void galaxies can also be found, whose star formation was shut down long ago.
Are the same processes that quench star formation in denser regions of the
Universe also at work in voids?
We compare the luminosity function of void galaxies in the 2dF Galaxy
Redshift Survey, to those from a galaxy formation model built on the Millennium
Simulation. We show that a global star formation suppression mechanism in the
form of low luminosity "radio mode" AGN heating is sufficient to reproduce the
observed population of void early-types. Radio mode heating is environment
independent other than its dependence on dark matter halo mass, where, above a
critical mass threshold of approximately M_vir~10^12.5 M_sun, gas cooling onto
the galaxy is suppressed and star formation subsequently fades. In the
Millennium Simulation, the void halo mass function is shifted with respect to
denser environments, but still maintains a high mass tail above this critical
threshold. In such void halos, radio mode heating remains efficient and red
galaxies are found; collectively these galaxies match the observed space
density without any modification to the model. Consequently, galaxies living in
vastly different large-scale environments but hosted by halos of similar mass
are predicted to have similar properties, consistent with observations.Comment: 6 pages, 3 figures, accepted MNRA
Examination of Annular-Electrode Spark Discharges in Flowing Oxygen - An Overview
A parametric study of annular spark gaps, pressures, and spark discharges in flowing oxygen gas was performed with a Champion spark exciter. The range of the pressure-distance product for the experiment is from approximately 50 torr-cm to 2500 torr-cm. Measurements of breakdown voltage qualitatively trend with Paschen's curve. Spark duration remained constant until the pressure-distance product exceeded 200 torr-cm, and then steadily increased. The mean spark energy increases linearly with the pressure-distance on a log-log plot indicating that a definite power relationship exists. The distribution of sparks at low energies and low pressures is not Gaussian and has no dominant peaks. Moderate and high spark energies are bimodal, with the dominant mode near 80 mJ. As pressure increases, dominant and secondary modes approach the same probability
Examination of Annular-Electrode Spark Discharges in Flowing Oxygen Experimental Nuances
Microsecond sparks and the resulting plume of hot gas/plasma were examined against a parametric pressure-distance matrix. Schlieren imaging is used to capture the spatial and temporal location of spark discharge exhaust for two milliseconds. Low pressure and larger gap widths created the largest size and intensity signal for the spark-affected plumes. Experimental exit-plume velocities trend well with analytic predictions using a mean pressure between the chamber and atmospheric conditions. Due to the quadratic relation of the annulus area and gap width, larger gap width velocities are more accurately represented by analytic predictions using atmospheric pressure as the larger exit area restricts the flow less. The same pressure adjustment, when applied to breakdown voltages, improves data alignment with Paschens Curve
The Structure of Halos: Implications for Group and Cluster Cosmology
The dark matter halo mass function is a key repository of cosmological
information over a wide range of mass scales, from individual galaxies to
galaxy clusters. N-body simulations have established that the
friends-of-friends (FOF) mass function has a universal form to a surprising
level of accuracy (< 10%). The high-mass tail of the mass function is
exponentially sensitive to the amplitude of the initial density perturbations,
the mean matter density parameter, Omega_m, and to the dark energy controlled
late-time evolution of the density field. Observed group and cluster masses,
however, are usually stated in terms of a spherical overdensity (SO) mass which
does not map simply to the FOF mass. Additionally, the widely used halo models
of structure formation -- and halo occupancy distribution descriptions of
galaxies within halos -- are often constructed exploiting the universal form of
the FOF mass function. This again raises the question of whether FOF halos can
be simply related to the notion of a spherical overdensity mass. By employing
results from Monte Carlo realizations of ideal Navarro-Frenk-White (NFW) halos
and N-body simulations, we study the relationship between the two definitions
of halo mass. We find that the vast majority of halos (80-85%) in the
mass-range 10^{12.5}-10^{15.5} M_sun/h indeed allow for an accurate mapping
between the two definitions (~ 5%), but only if the halo concentrations are
known. Nonisolated halos fall into two broad classes: those with complex
substructure that are poor fits to NFW profiles and those ``bridged'' by the
(isodensity-based)FOF algorithm. A closer investigation of the bridged halos
reveals that the fraction of these halos and their satellite mass distribution
is cosmology dependent. (abridged)Comment: Submitted to Ap
Deployment of autonomous IoT drones for precision farming in an automated manner
Precision farming (PF), as described by European Commission, is a management approach that focuses on (near real-time) observation, measurement, and responses to variability in crops, fields and animals; it can help increase crop yields and animal performance, reduce costs, including labour costs, and optimise process inputs; all of these can help increase profitability; at the same time, PF can increase work safety and reduce the environmental impacts of agriculture and farming practices, thus contributing to the sustainability of agricultural production. Vehicles are becoming increasingly automated by taking on more and more tasks under improving intelligent control systems equipped with enhancing low-power monitoring sensor technologies and Artificial Intelligence (AI) techniques. Autonomous Unmanned Aerial Vehicles (UAVs) (A-UAVs), as flying autonomous robots, with self-learning and self-decision-making abilities by executing non-trivial sequences of events with decimetre-level accuracy based on a set of rules, control loops and constraints using dynamic flight plans involving autonomous take-off and landing are taking their indispensable parts with little or no human in the loop to accomplish various automated tasks. PF is one of the most promising applications showing the benefits of using drones where a lack of human element in the farming industry is becoming evident. For instance, remote monitoring using Internet of Things (IoT) UAVs is safe, cost-effective and could be easily and frequently repeated, providing prompt information about livestock's population size and their instant location and health-related issues. The University of Central Lancashire (UCLan) has been developing intelligent IoT drones to execute numerous tasks in various disciplines (https://www.uclan.ac.uk/business/archive/lidz) for a decade within the concept of Automation of Everything (AoE) and Internet of Everything (IoE) using several supervised and unsupervised AI techniques. This research demonstrates how highly integrated technologies with drones can help the farming industry overcome challenging issues. Intelligent UAVs can overtake some of the labour-intensive tasks to execute PF. The integration of UAVs embedded with IoT and sensor-driven technologies into farming can improve productivity with substantial cost savings. IoT technologies instilled with AI techniques can lead to automated ways of performing daily routines in large farms. Within this perspective, in this event, several examples of PF-based IoT drones and their equipment, developed by UCLan, are demonstrated
Non-Invasive Detection of Landmines, Unexploded Ordnances and Improvised Explosive Devices Using Bespoke Unmanned Aerial Vehicles
Finding and removing legacy landmines, Unexploded Ordnances (UXO), and Improvised Explosive Devices (IED) with a team of people or animals is very dangerous and requires a lot of effort and time. A small-scale customised drone was created in this research to automate the processes of cleaning explosive devices. Field tests were conducted to evaluate its performance. The outcomes of the benchmark evaluations and open-air minefields confirm the feasibility of the technologies, procedures, and strategies used in this study to identify landmines/UXO/IDE effectively
Mergers in Lambda-CDM: Uncertainties in Theoretical Predictions and Interpretations of the Merger Rate
Different methodologies lead to order-of-magnitude variations in predicted
galaxy merger rates. We examine and quantify the dominant uncertainties.
Different halo merger rates and subhalo 'destruction' rates agree to within a
factor ~2 given proper care in definitions. If however (sub)halo masses are not
appropriately defined or are under-resolved, the major merger rate can be
dramatically suppressed. The dominant differences in galaxy merger rates owe to
baryonic physics. Hydrodynamic simulations without feedback and older models
that do not agree with the observed galaxy mass function propagate factor ~5
bias in the resulting merger rates. However, if the model matches the galaxy
mass function, properties of central galaxies are sufficiently converged to
give small differences in merger rates. But variations in baryonic physics of
satellites also have dramatic effects. The known problem of satellite
'over-quenching' in most semi-analytic models (SAMs), whereby SAM satellites
are too efficiently stripped of gas, could lead to order-of-magnitude
under-estimates of merger rates for low-mass, gas-rich galaxies. Fixing the
satellite properties to observations tends to predict higher merger rates, but
with factor ~2 empirical uncertainties. Choice of mass ratio definition
matters: at low masses, most true major mergers (in baryonic/dynamical galaxy
mass) will appear to be minor mergers in their stellar or luminosity mass
ratio. Observations and models using these criteria may underestimate major
merger rates by factors ~5. Orbital parameters and gas fractions also introduce
factor ~3 differences in amount of bulge formed by mergers, even for fixed mass
ratio encounters.Comment: 32 Pages, 15 figures, accepted to ApJ (revised to match accepted
version and correct Fig. 12
The clustering of the first galaxy halos
We explore the clustering properties of high redshift dark matter halos,
focusing on halos massive enough to host early generations of stars or galaxies
at redshift 10 and greater. Halos are extracted from an array of dark matter
simulations able to resolve down to the "mini-halo" mass scale at redshifts as
high as 30, thus encompassing the expected full mass range of halos capable of
hosting luminous objects and sources of reionization. Halo clustering on
large-scales agrees with the Sheth, Mo & Tormen halo bias relation within all
our simulations, greatly extending the regime where large-scale clustering is
confirmed to be "universal" at the 10-20% level (which means, for example, that
3sigma halos of cluster mass at z=0 have the same large-scale bias with respect
to the mass distribution as 3sigma halos of galaxy mass at z=10). However, on
small-scales, the clustering of our massive halos (> ~10^9 Msun/h) at these
high redshifts is stronger than expected from comparisons with small-scale halo
clustering extrapolated from lower redshifts. This implies "non-universality"
in the scale-dependence of halo clustering, at least for the commonly used
parameterizations of the scale-dependence of bias that we consider. We provide
a fit for the scale-dependence of bias in our results. This study provides a
basis for using extraordinarily high redshift galaxies (redshift ~10) as a
probe of cosmology and galaxy formation at its earliest stages. We show also
that mass and halo kinematics are strongly affected by finite simulation
volumes. This suggests the potential for adverse affects on gas dynamics in
hydrodynamic simulations of limited volumes, such as is typical in simulations
of the formation of the "first stars", though further study is warranted.Comment: MNRAS accepte