30,558 research outputs found
Pattern Identification - A Foundation for Research in the Emphasis of Design Patterns in Systems Engineering and Knowledge Capture
Pattern Language describes the morphology and functionality of a system in the absence of design particulars. Harnessing this capability will provide the Systems Engineering discipline a means of managing the development of increasingly complex systems with increasingly distributed design teams while capturing and retaining knowledge for future generations. Pattern Language is a syntax for describing, and structurally relating, design patterns. Design patterns contextually describe the application of domain knowledge in the engineered solution to the force balance problem. The parallels between pattern recognition and application, as a fundamental stage of human learning, and pattern observation within a complex system, suggests pattern language may be a valuable tool in the capture and dissemination of knowledge. Pattern application has enjoyed considerable study over the last several decades, however much of this work has focused on the replication of design particulars. This work returns to the roots of Pattern Language and explores the utility of patterns as an architectural description and guide, and knowledge capture method, for complex system development beginning with the identification of a time proven design pattern
Strong and Weak Optimizations in Classical and Quantum Models of Stochastic Processes
Among the predictive hidden Markov models that describe a given stochastic
process, the {\epsilon}-machine is strongly minimal in that it minimizes every
R\'enyi-based memory measure. Quantum models can be smaller still. In contrast
with the {\epsilon}-machine's unique role in the classical setting, however,
among the class of processes described by pure-state hidden quantum Markov
models, there are those for which there does not exist any strongly minimal
model. Quantum memory optimization then depends on which memory measure best
matches a given problem circumstance.Comment: 14 pages, 14 figures;
http://csc.ucdavis.edu/~cmg/compmech/pubs/uemum.ht
GPS antenna designs
Application of the current GPS NAVSTAR system to civilian service requires that a right hand, circularly polarized, -160 dBW spread spectrum signal be received from an orbiting satellite, where the antenna environment is also moving. This presents a design challenge when inexpensive antennas are desired. The intent of this survey is to provide information on the antennas mentioned and to construct and test prototypes to determine whether the choice made by the industry, the quadrifilar helix, is the best. The helix antenna is currently the low cost standard for GPS. Prototype versions were constructed using 12 gauge wire and subminiature coaxial hardline. The constructed antennas were tested using a signal generator and a reference turnstile. A spectrum analyzer was used to measure the level of the received signal
GPS experiments
A method of collecting positional data has been devised using the Federal Aviation Administration (FAA) receiver built by Lincoln Labs which was originally designed for service as a long-term monitoring station. Modification of the receiver continues and this will allow its use as an aircraft navigator. Additional effort has been spent on the development of an experimental receiver or test bed receiver that would allow modification and implementation of new Global Positioning System (GPS) receiver design concepts
Generating Macroscopic Superpositions with Interacting Bose-Einstein Condensates: Multi-Mode Speed-Ups and Speed Limits
We theoretically investigate the effect of multi-mode dynamics on the
creation of macroscopic superposition states (spin-cat states) in Bose-Einstein
condensates via one-axis twisting. A two-component Bose-Einstein condensate
naturally realises an effective one-axis twisting interaction, under which an
initially separable state will evolve toward a spin-cat state. However, the
large evolution times necessary to realise these states is beyond the scope of
current experiments. This evolution time is proportional to the degree of
asymmetry in the relative scattering lengths of the system, which results in
the following trade-off; faster evolution times are associated with an increase
in multi-mode dynamics, and we find that generally multi-mode dynamics reduce
the degree of entanglement present in the final state. However, we find that
highly entangled cat-like states are still possible in the presence of
significant multi-mode dynamics, and that these dynamics impose a speed-limit
on the evolution such states
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