Showing papers by "Albion College published in 1987"

Consumption and Politics at Aztec Huexotla

Abstract: Les changements politiques survenus dans le petit royaume d'Huexotla, dans la vallee de Mexico, avec son integration a l'Empire azteque, vus a travers la transformation des biens consommes par les edites locales. Les biens de l'elite sont le signe de leur statut social et l'empire azteque a utilise son tribut pour faire circuler une grande quantite de biens de prestige afin d'asseoir sa domination

The Symbolic Growth Experience Paradigm for a Humanistic-Existential Learning Theory

Abstract: The Symbolic Growth Experience (SGE) refers to those significant moments in life when we create personal meaning by symbolizing our immediate experience in the interest of heightened awareness and ...

Navigation Planning Using Quadtrees

Abstract: An algorithm is presented for planning a 2-D collision-free path for a mobile robot in an unstructured work environment. The algorithm assumes the existence of a pixel map of all or part of the environment, where each pixel is either on (implying blocked) or off (implying clear). The goal is to compute a "reasonable path" between two points in a minimal amount of time, and this is achieved through a "compressed" representation of the pixel map using a modified quadtree data structure and a procedure for smoothing the resulting path. The algorithm has been coded in the C programming language to facilitate portability, and the results of tests made on "realistic" indoor environments are presented. A discussion on how the environmental maps were obtained is also included.

Outer and Inner Confidence Intervals for Finite Population Quantile Intervals

Abstract: Let π N be a finite population of size N whose elements have distinct X values X (1) < … < X (N). Let x (1) < … < x (n) denote the order statistics of a simple random sample of size n taken from π N without replacement. An outer confidence interval is formed for the quantile interval [X (t), X (u)] (1 ≤ t < u ≤ N) of the form [x (r),x(s)], where 1 ≤ r < s ≤ n and r ≤ t, and an exact expression is derived for the associated confidence coefficient as Pr[x (r) ≤ X (t) < X (u) ≤ x (s)]. A brief table (see Table 1) of confidence coefficients is included, along with several extensions. For example, consider a population of size N = 399 distinct elements. Suppose that we want a 95% or greater confidence interval for the interval in which the middle half of the population lies: [X (100), X (300) Table 1 shows that, based on a simple random sample of size n = 20, the second and nineteenth order statistics of the sample yield a confidence interval [x (2), x (19)] with confidence coefficient 95.7%. In a sim...

A Real-Time Expert System For Control Of An Autonomous Mobile Robot Including Diagnosis Of Unexpected Occurrences

Abstract: An autonomous mobile robot deals with the empirical world which is never fully predictable, hence it must continually monitor its performance by comparing the actual responses of sensors to their expected responses. Where a discrepancy occurs, the source of the discrepancy must be diagnosed and on-line corrective actions or replanning may be required. The use of a production system for the control of an autonomous robot presents several attractive features: the explicitness and homogeneity of the knowledge representation facilitates explaining, verifying and modifying the rules which determine the robot's behavior; it also permits the incremental extension of the domain of competence. However, real-time operation poses a number of challenges due to the dynamic nature of the data and because the system must frequently deal with a large knowledge base in a limited time. An implementation of a control system is discussed where a large commercial real-time expert system originally designed for industrial process diagnostics was adapted to the control of an autonomous mobile robot for planning, executing and monitoring a set of navigational tasks. One of the essential components of the problem domain is the occurrence of an "unexpected" happening e.g., as new obstacles are moved into the domain during the robot traverse, or when an obstacle undetectable by the long-range sonar sensors is suddenly observed by a proximity sensor. In a recent demonstration of the system, the detection of a problem generated an interrupt alarm, a diagnostic procedure, and a new plan, which was successfully executed in real time.