1,233 research outputs found
Computer modeling of arc drivers
Model is generated from description of element connections involved in complete arc network, list of corresponding circuit element values, description of circuit current excitation, and list of out-puts desired. Waveform of current is determined by structure of capacitor storage system, driver geometry, and preset driver conditions
Exploding wire initiation and electrical operation of a 40-kV system for arc-heated drivers up to 10 feet long
Exploding wire initiation and electrical operation of 40 kV system for arc heated drivers up to 10 feet lon
Arc driver operation for either efficient energy transfer or high-current generator
An investigation is made to establish predictable electric arcs along triggered paths for research purposes, the intended application being the heating of the driver gas of a 1 MJ electrically driven shock tube. Trigger conductors consisting of wires, open tubes, and tubes pressurized with different gases were investigated either on the axis of the arc chamber or spiraled along the chamber walls. Design criteria are presented for successful arc initiation with reproducible voltage-current characteristics. Results are compared with other facilities and several application areas are discussed
The Intelligent Music Editor: Towards an Automated Platform for Music Analysis and Editing
Abstract. Digital music editing is a standard process in music production for correcting mistakes and enhancing quality, but this is tedious and time-consuming. The Intelligent Music Editor, or IMED, automates routine music editing tasks using advanced techniques for music transcription (especially score alignment), and signal processing. The IMED starts with multiple recorded tracks and a detailed score that specifies all of the notes to be played. A transcription algorithm locates notes in the recording and identifies their pitch. A scheduling model tracks instantaneous tempo of the recorded performance and determines adjusted timings for output tracks. A time-domain pitch modification/time stretching algorithm performs pitch correction and time adjustment. An empirical evaluation on a multi-track recording illustrates the proposed algorithms achieve an onset detection accuracy of 87 % and a detailed subjective evaluation shows that the IMED improves pitch and timing accuracy while retaining the expressive nuance of the original recording
A Laboratory Investigation of Supersonic Clumpy Flows: Experimental Design and Theoretical Analysis
We present a design for high energy density laboratory experiments studying
the interaction of hypersonic shocks with a large number of inhomogeneities.
These ``clumpy'' flows are relevant to a wide variety of astrophysical
environments including the evolution of molecular clouds, outflows from young
stars, Planetary Nebulae and Active Galactic Nuclei. The experiment consists of
a strong shock (driven by a pulsed power machine or a high intensity laser)
impinging on a region of randomly placed plastic rods. We discuss the goals of
the specific design and how they are met by specific choices of target
components. An adaptive mesh refinement hydrodynamic code is used to analyze
the design and establish a predictive baseline for the experiments. The
simulations confirm the effectiveness of the design in terms of articulating
the differences between shocks propagating through smooth and clumpy
environments. In particular, we find significant differences between the shock
propagation speeds in a clumpy medium compared to a smooth one with the same
average density. The simulation results are of general interest for foams in
both inertial confinement fusion and laboratory astrophysics studies. Our
results highlight the danger of using average properties of inhomogeneous
astrophysical environments when comparing timescales for critical processes
such as shock crossing and gravitational collapse times.Comment: 7 pages, 6 figures. Submitted to the Astrophysical Journal. For
additional information, including simulation animations and the pdf and ps
files of the paper with embedded high-quality images, see
http://pas.rochester.edu/~wm
Can the Renormalization Group Improved Effective Potential be used to estimate the Higgs Mass in the Conformal Limit of the Standard Model?
We consider the effective potential in the standard model with a single
Higgs doublet in the limit that the only mass scale present is
radiatively generated. Using a technique that has been shown to determine
completely in terms of the renormalization group (RG) functions when using the
Coleman-Weinberg (CW) renormalization scheme, we first sum leading-log (LL)
contributions to using the one loop RG functions, associated with five
couplings (the top quark Yukawa coupling , the quartic coupling of the Higgs
field , the SU(3) gauge coupling , and the couplings
and ). We then employ the two loop RG functions with the three couplings
, , to sum the next-to-leading-log (NLL) contributions to and
then the three to five loop RG functions with one coupling to sum all the
contributions to . In order to compute these sums, it is
necessary to convert those RG functions that have been originally computed
explicitly in the minimal subtraction (MS) scheme to their form in the CW
scheme. The Higgs mass can then be determined from the effective potential: the
result is decreases to at
order and at order. No reasonable
estimate of can be made at orders or . This is taken
to be an indication that this mechanism for spontaneous symmetry breaking is in
fact viable, though one in which there is slow convergence towards the actual
value of . The mass is argued to be an upper bound on
.Comment: 24 pages, 5 figures. Updated version contains new discussion,
references, figures, and corrects errors in reference
A Subsumption Agent for Collaborative Free Improvisation
This paper discusses the design and evaluation of an artificial agent for collaborative musical free improvisation. The agent provides a means to investigate the underpinnings of improvisational interaction. In connection with this general goal, the system is also used here to explore the implementation of a collaborative musical agent using a specific robotics architecture, Subsumption. The architecture of the system is explained, and its evaluation in an empirical study with expert improvisors is discussed. A follow-up study using a second iteration of the system is also presented. The system design and connected studies bring together Subsumption robotics, ecological psychology, and musical improvisation, and contribute to an empirical grounding of an ecological theory of improvisation
Human-Computer Music Performance: From Synchronized Accompaniment to Musical Partner
Live music performance with computers has motivated many research projects in science, engineering, and the arts. In spite of decades of work, it is surprising that there is not more technology for, and a better understanding of the computer as music performer. We review the development of techniques for live music performance and outline our efforts to establish a new direction, Human-Computer Music Performance (HCMP), as a framework for a variety of coordinated studies. Our work in this area spans performance analysis, synchronization techniques, and interactive performance systems. Our goal is to enable musicians to ncorporate computers into performances easily and effectively through a better understanding of requirements, new techniques, and practical, performance-worthy implementations. We conclude with directions for future work
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