139,372 research outputs found
Lithic economies and community organization at La Laguna, Tlaxcala
Site-wide, assemblage-based lithic analyses help to elucidate community dynamics including variability in domestic economies, technological skill and decision making, exchange networks, and ritual practices. In this study we present the results of an analysis of over 36,000 lithic artifacts from the site of La Laguna, Tlaxcala. We compare Middle to Late Formative period (ca. 600β400 b.c.) and Terminal Formative period (ca. 100 b.c.βa.d. 150) deposits to examine transformations associated with urbanization and state formation during this interval. The residents of La Laguna had relatively equal and ample access to obsidian, and most production was organized independently by households. We identify blade production zones and variability in consumption patterns suggestive of different domestic, communal, and ceremonial activities. The introduction of bloodletters, elaborate large bifacial knives, and zoomorphic eccentrics to the Terminal Formative assemblage may indicate the emergence of higher statuses, new social roles, and militaristic symbolism during this period
Some comments on Monte Carlo and molecular dynamics methods
We highlight some links between molecular dynamics and Monte Carlo algorithms used to simulate condensed matter systems. Special attention is paid to the question of sampling the desired statistical ensemble
Development of an automated aircraft subsystem architecture generation and analysis tool
Purpose β The purpose of this paper is to present a new computational framework to address future
preliminary design needs for aircraft subsystems. The ability to investigate multiple candidate
technologies forming subsystem architectures is enabled with the provision of automated architecture
generation, analysis and optimization. Main focus lies with a demonstration of the frameworks
workings, as well as the optimizers performance with a typical form of application problem.
Design/methodology/approach β The core aspects involve a functional decomposition, coupled
with a synergistic mission performance analysis on the aircraft, architecture and component levels.
This may be followed by a complete enumeration of architectures, combined with a user defined
technology filtering and concept ranking procedure. In addition, a hybrid heuristic optimizer, based on
ant systems optimization and a genetic algorithm, is employed to produce optimal architectures in both
component composition and design parameters. The optimizer is tested on a generic architecture
design problem combined with modified Griewank and parabolic functions for the continuous space.
Findings β Insights from the generalized application problem show consistent rediscovery of the
optimal architectures with the optimizer, as compared to a full problem enumeration. In addition
multi-objective optimization reveals a Pareto front with differences in component composition as well
as continuous parameters.
Research limitations/implications β This paper demonstrates the frameworks application on a
generalized test problem only. Further publication will consider real engineering design problems.
Originality/value β The paper addresses the need for future conceptual design methods of complex
systems to consider a mixed concept space of both discrete and continuous nature via automated methods
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