2,676 research outputs found
In-Situ absolute phase detection of a microwave field via incoherent fluorescence
Measuring the amplitude and the absolute phase of a monochromatic microwave
field at a specific point of space and time has many potential applications,
including precise qubit rotations and wavelength quantum teleportation. Here we
show how such a measurement can indeed be made using resonant atomic probes,
via detection of incoherent fluorescence induced by a laser beam. This
measurement is possible due to self-interference effects between the positive
and negative frequency components of the field. In effect, the small cluster of
atoms here act as a highly localized pick-up coil, and the fluorescence channel
acts as a transmission line.Comment: 13 pages, 5 figure
Multi-Disciplinary Capstone Project on Self-Replicating 3-D Printer
This paper explores the dynamics of a multi-semester multi-disciplinary team approach applied within a traditional senior capstone project that involves strong design and manufacturing components. In addition, the logistics of running a successful senior project will be discussed along with the associated problems of organization within a multi-program environment. The key drivers and motivators behind this paper are, most importantly, that multi-disciplinary teams are very common in industry and that our industrial advisory boards for Electrical Engineering Technology (EET) and Mechanical Engineering Technology (MET) suggested that we do more multi-disciplinary projects. Furthermore, this multi-disciplinary team approach will satisfy the proposed ABET/ETAC outcomes for 2016. The Proposed Revisions to the Program Criteria for Mechanical Engineering Technology and Similarly Named Programs ABET/ETAC outcomes say “The capstone experience, ideally multidisciplinary in nature, must be project based and include formal design, implementation and test processes.” (emphasis added) Faculty searched for a technology that would allow both EET and MET students to contribute equally to the success of the project, and decided upon additive manufacturing. Students have been exposed extensively through formal course material covering 3D printing technology and would be familiar with the operation of 3D printers in general. Therefore, it was reasoned a familiarity with the project goal of designing and constructing a self-replicating 3D printer would give students more confidence in tackling the difficult task of managing an extended project over both the design and manufacture phases, and mastering effective communicate across disciplines. The student team organization mirrors current industry standard operating procedures. First, the team is multidisciplinary, including EET students with programing and circuits skills and MET students with CAD, design, mechanical analysis skills. All students must demonstrate project process skills, utilizing current design for six-sigma procedures. The students learn a standard set of tools to manage the project, as well as synthesize those tools with their discipline specific knowledge. Because of the program curriculum plans, the EET students are involved in the project for two semesters. The MET students have a one semester project course; this enables one group of MET students to design the mechanical system, document their work, and pass it on to a second team for implementation. This was considered a positive based on what is typical in industry, where engineering groups are constantly interfacing. Results include observations of group member dynamics, quality of work, timeliness, budget management, and communication across disciplines. Rubrics to document student achievement of outcomes are used
Seawater Desalination for Municipal Water Production
This paper examines the optimal allocation of several inputs in the context of seawater desalination by reverse osmosis (RO) as a source of municipal (or commercial or industrial) water. A cost-minimization model is developed, a production function is estimated, and sensitivity analyses are conducted using the optimization model to investigate the effect of environmental conditions and economic factors on the optimal input portfolio and the cost of operating a modeled seawater desalination facility. The objectives of this paper are to better understand the effect on the seawater desalination facility’s costs and input portfolio from changes in water quality, membrane lifespan, daily operations schedule, and energy prices. Findings include that lower total facility costs are associated with warm-weather water quality parameters, longer membrane life, and mid-range daily operations schedule (14.265 hours/day). Under most conditions, an interruptible power supply regime reduces facility costs. Exceptions include when the interruptible power supply regime implies significant reductions in operating hours and the associated reduction in energy price is very small.water, production, seawater desalination, Resource /Energy Economics and Policy,
Determination of the phase of an electromagnetic field via incoherent detection of fluorescence
We show that the phase of a field can be determined by incoherent detection
of the population of one state of a two-level system if the Rabi frequency is
comparable to the Bohr frequency so that the rotating wave approximation is
inappropriate. This implies that a process employing the measurement of
population is not a square-law detector in this limit. We discuss how the
sensitivity of the degree of excitation to the phase of the field may pose
severe constraints on precise rotations of quantum bits involving low-frequency
transitions. We present a scheme for observing this effect in an atomic beam,
despite the spread in the interaction time.Comment: 4 pages, 2 fig
Fault Models for Quantum Mechanical Switching Networks
The difference between faults and errors is that, unlike faults, errors can
be corrected using control codes. In classical test and verification one
develops a test set separating a correct circuit from a circuit containing any
considered fault. Classical faults are modelled at the logical level by fault
models that act on classical states. The stuck fault model, thought of as a
lead connected to a power rail or to a ground, is most typically considered. A
classical test set complete for the stuck fault model propagates both binary
basis states, 0 and 1, through all nodes in a network and is known to detect
many physical faults. A classical test set complete for the stuck fault model
allows all circuit nodes to be completely tested and verifies the function of
many gates. It is natural to ask if one may adapt any of the known classical
methods to test quantum circuits. Of course, classical fault models do not
capture all the logical failures found in quantum circuits. The first obstacle
faced when using methods from classical test is developing a set of realistic
quantum-logical fault models. Developing fault models to abstract the test
problem away from the device level motivated our study. Several results are
established. First, we describe typical modes of failure present in the
physical design of quantum circuits. From this we develop fault models for
quantum binary circuits that enable testing at the logical level. The
application of these fault models is shown by adapting the classical test set
generation technique known as constructing a fault table to generate quantum
test sets. A test set developed using this method is shown to detect each of
the considered faults.Comment: (almost) Forgotten rewrite from 200
The 21-SPONGE HI Absorption Survey I: Techniques and Initial Results
We present methods and results from "21-cm Spectral Line Observations of
Neutral Gas with the EVLA" (21-SPONGE), a large survey for Galactic neutral
hydrogen (HI) absorption with the Karl G. Jansky Very Large Array (VLA). With
the upgraded capabilities of the VLA, we reach median root-mean-square (RMS)
noise in optical depth of per
channel for the 31 sources presented here. Upon
completion, 21-SPONGE will be the largest HI absorption survey with this high
sensitivity. We discuss the observations and data reduction strategies, as well
as line fitting techniques. We prove that the VLA bandpass is stable enough to
detect broad, shallow lines associated with warm HI, and show that bandpass
observations can be combined in time to reduce spectral noise. In combination
with matching HI emission profiles from the Arecibo Observatory (
angular resolution), we estimate excitation (or spin) temperatures ()
and column densities for Gaussian components fitted to sightlines along which
we detect HI absorption (30/31). We measure temperatures up to for individual lines, showing that we can probe the
thermally unstable interstellar medium (ISM) directly. However, we detect fewer
of these thermally unstable components than expected from previous
observational studies. We probe a wide range in column density between
and for individual HI clouds. In addition,
we reproduce the trend between cold gas fraction and average found by
synthetic observations of a hydrodynamic ISM simulation by Kim et al. (2014).
Finally, we investigate methods for estimating HI and discuss their
biases.Comment: Accepted for publication in ApJ; 24 pages, 14 figure
Space-charge-limited current density for nonplanar diodes with monoenergetic emission using Lie-point symmetries
Understanding space-charge limited current density (SCLCD) is fundamentally
and practically important for characterizing many high-power and high-current
vacuum devices. Despite this, no analytic equations for SCLCD with nonzero
monoenergetic initial velocity have been derived for nonplanar diodes from
first principles. Obtaining analytic equations for SCLCD for nonplanar
geometries is often complicated by the nonlinearity of the problem and over
constrained boundary conditions. In this letter, we use the canonical
coordinates obtained by identifying Lie-point symmetries to linearize the
governing differential equations to derive SCLCD for any orthogonal diode.
Using this method, we derive exact analytic equations for SCLCD with a
monoenergetic injection velocity for one-dimensional cylindrical, spherical,
tip-to-tip (t-t), and tip-to-plate (t-p) diodes. We specifically demonstrate
that the correction factor from zero initial velocity to monoenergetic emission
depends only on the initial kinetic and electric potential energies and not on
the diode geometry and that SCLCD is universal when plotted as a function of
the canonical gap size. We also show that SCLCD for a t-p diode is a factor of
four larger than a t-t diode independent of injection velocity. The results
reduce to previously derived results for zero initial velocity using
variational calculus and conformal mapping.Comment: 18 pages, 3 figure
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