9,499 research outputs found
Stochastic Data Clustering
In 1961 Herbert Simon and Albert Ando published the theory behind the
long-term behavior of a dynamical system that can be described by a nearly
uncoupled matrix. Over the past fifty years this theory has been used in a
variety of contexts, including queueing theory, brain organization, and
ecology. In all these applications, the structure of the system is known and
the point of interest is the various stages the system passes through on its
way to some long-term equilibrium.
This paper looks at this problem from the other direction. That is, we
develop a technique for using the evolution of the system to tell us about its
initial structure, and we use this technique to develop a new algorithm for
data clustering.Comment: 23 page
Orientation-dependent pseudomorphic growth of InAs for use in lattice-mismatched mid-infrared photonic structures
In this study, InAs was deposited on GaAs (100) and GaAs (111)B 2 degrees towardssubstrates for the purpose of differentiating the InAs growth mode stemming from strain and then analyzed using in-situ reflection high energy electron diffraction, scanning electron microscopy, Raman spectroscopy, reflectance spectroscopy, and atomic force microscopy. The procession of InAs deposition throughout a range of deposition conditions results in assorted forms of strain relief revealing that, despite lattice mismatch for InAs on GaAs (approximately 7%), InAs does not necessarily result in typical quantum dot/wire formation on (111) surfaces, but instead proceeds two-dimensionally due primarily to the surface orientation
Fast Bunch Integrators at Fermilab During Run II
The Fast Bunch Integrator is a bunch intensity monitor designed around the
measurements made from Resistive Wall Current Monitors. During the Run II
period these were used in both Tevatron and Main Injector for single and
multiple bunch intensity measurements. This paper presents an overview of the
design and use of these systems during this period.Comment: 6 p
Holographic Chern-Simons Defects
We study SU(N) Yang-Mills-Chern-Simons theory in the presence of defects that
shift the Chern-Simons level from a holographic point of view by embedding the
system in string theory. The model is a D3-D7 system in Type IIB string theory,
whose gravity dual is given by the AdS soliton background with probe D7-branes
attaching to the AdS boundary along the defects. We holographically renormalize
the free energy of the defect system with sources, from which we obtain the
correlation functions for certain operators naturally associated to these
defects. We find interesting phase transitions when the separation of the
defects as well as the temperature are varied. We also discuss some
implications for the Fractional Quantum Hall Effect and for two-dimensional
QCD.Comment: 56 pages, 19 figures, v2: sign convention for CS level in terms of
number of D7 branes switched, UV behavior of one and two point functions
added in sec. 5.4.1 and 5.4.3, references added, typos correcte
Lunar Sample Compendium
The purpose of the Lunar Sample Compendium will be to inform scientists, astronauts and the public about the various lunar samples that have been returned from the Moon. This Compendium will be organized rock by rock in the manor of a catalog, but will not be as comprehensive, nor as complete, as the various lunar sample catalogs that are available. Likewise, this Compendium will not duplicate the various excellent books and reviews on the subject of lunar samples (Cadogen 1981, Heiken et al. 1991, Papike et al. 1998, Warren 2003, Eugster 2003). However, it is thought that an online Compendium, such as this, will prove useful to scientists proposing to study individual lunar samples and should help provide backup information for lunar sample displays. This Compendium will allow easy access to the scientific literature by briefly summarizing the significant findings of each rock along with the documentation of where the detailed scientific data are to be found. In general, discussion and interpretation of the results is left to the formal reviews found in the scientific literature. An advantage of this Compendium will be that it can be updated, expanded and corrected as need be
Spectroscopy studies of straincompensated mid-infrared QCL active regions on misoriented substrates
In this work, we perform spectroscopic studies of AlGaAs/InGaAs quantum cascade laser structures that demonstrate frequency mixing using strain-compensated active regions. Using a three-quantum well design based on diagonal transitions, we incorporate strain in the active region using single and double well configurations on various surface planes (100) and (111). We observe the influence of piezoelectric properties in molecular beam epitaxy grown structures, where the addition of indium in the GaAs matrix increases the band bending in between injector regions and demonstrates a strong dependence on process conditions that include sample preparation, deposition rates, mole fraction, and enhanced surface diffusion lengths. We produced mid-infrared structures under identical deposition conditions that differentiate the role of indium(strain) in intracavity frequency mixing and show evidence that this design can potentially be implemented using other material systems
Equipment replacement: an integration view
Economic models for equipment replacement have been criticized for their inability to adequately capture the economic benefits of investments in modern technological equipment. In this paper, new models are developed that integrate the factors of machine utilization, interactions of equipment in a manufacturing system, and the manufacturing system\u27s influence on product demand into the economic analysis process
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