The Team Balancing Act - Enhancing Knowledge - Building Activity in On-Line Learning Communities

Online learning in the university sector is a given. Constructivist views of learning (often team based) and the notion of knowledge-building, mediated through the use of ICTs seemingly address many of the imperatives to equip individuals for emergent knowledge-age work practice. While teamwork has many perceived advantages, teams also inexplicably fail despite the apparent quality of the participants. Teams are successful when members address what is a relatively narrow range of actions. However, even within this limited range of actions individuals demonstrate definite preferences towards certain activities and roles. This paper reports on the findings from a study that investigated if knowledge-building activity can be enhanced in tertiary education CSCL environments through the use of groups balanced by Team Role Preference (Margerison & McCann, 1995, 1998). The study found that higher quality knowledge-building activity was more likely to occur in balanced groups than in random groups. The analysis of data revealed that a diversity of ideas was more likely to emerge from within balanced groups than from within random groups particularly when the random groups were heavily skewed towards one team role preference. This provided a compelling reason for explaining why balanced groups may lead to better knowledge-building activity

Tightly Coupled GNSS and Vision Navigation for Unmanned Air Vehicle Applications

This paper explores the unique benefits that can be obtained from a tight integration of a GNSS sensor and a forward-looking vision sensor. The motivation of this research is the belief that both GNSS and vision will be integral features of future UAV avionics architectures, GNSS for basic aircraft navigation and vision for obstacle-aircraft collision avoidance. The paper will show that utilising basic single-antenna GNSS measurements and observables, along with aircraft information derived from optical flow techniques creates unique synergies. Results of the accuracy of attitude estimates will be presented, based a comprehensive Matlab® Simulink® model which re-creates an optical flow stream based on the flight of an aircraft. This paper establishes the viability of this novel integrated GNSS/Vision approach for use as the complete UAV sensor package, or as a backup sensor for an inertial navigation system

Dissent and Fallay in Dickerson v. United States

In his dissent from the majority in Dickerson, Justice Scalia (joined by Justice Thomas) argues that the Court acts in plain violation of the Constitution when it denies effect to this Act of Congress. This Essay aims to show that an important part of the reasoning in his dissent is fallacious, and insofar as the dissent is influenced by this reasoning, it is without value. Because dissenting opinions generally, and those of the Supreme Court especially, can become valuable in subsequent legal opinions and analyses, and because logic has a clear and important role to play in legal reasoning, it is important to recognize when fallacies occur in dissenting Supreme Court opinions and to understand the precise nature of any such fallacy

Race, Family, and Obligation

The Martin Luther King Jr. Day Lecture Presented to the WMU Center for the Study of Ethics in Society, January 16, 1995

Ignition and combustion of lunar propellants

The ignition and combustion of Al, Mg, and Al/Mg alloy particles in 99 percent O2/1 percent N2 mixtures is investigated at high temperatures and pressures for rocket engine applications. The 20 micron particles contain 0, 5, 10, 20, 40, 60, 80, and 100 weight percent Mg alloyed with Al, and are ignited in oxygen using the reflected shock in a shock tube near the endwall. Using this technique, the ignition delay and combustion times of the particles are measured at temperatures up to 3250 K as a function of Mg content for oxygen pressures of 8.5, 17, and 34 atm. An ignition model is developed which employs a simple lumped capacitance energy equation and temperature and pressure dependent particle and gas properties. Good agreement is achieved between the measured and predicted trends in the ignition delay times. For the particles investigated, the contribution of heterogeneous reaction to the heating of the particle is found to be significant at lower temperatures, but may be neglected as gas temperatures above 3000 K. As little as 10 percent Mg reduces the ignition delay time substantially at all pressures tested. The particle ignition delay times decrease with increasing Mg content, and this reduction becomes less pronounced as oxidizer temperature and pressure are increased

Measuring the Cognitive Domain of the Quality of Student Life: An Instrument for Faculties of Education

This study presents an instrument for measuring the cognitive domain of the quality of student life in faculties of education, developed using a representative sample of undergraduate and graduate students at a major Canadian university. The findings suggest there are three dimensions of the cognitive domain of the quality of student life: Development of Pupils, Subject Expertise, and the Methodology of Teaching. Alpha reliability coefficients for these scales ranged from 0.72 to 0.75. Cette étude présente un instrument servant à évaluer la facette cognitive de la qualité de la vie étudiante dans les facultés de sciences de l’éducation, instrument mis au point à l’aide d’un échantillon représentatif d’étudiants des premier, deuxième et troisième cycles dans une grande université canadienne. Les conclu- sions semblent indiquer que la facette cognitive de la qualité de la vie étudiante comprend trois dimensions: le développement des étudiants, la maîtrise du sujet d’étude et la méthodologie pédagogique. Les coefficients de fidélité alpha pour ces échelles variaient entre 0,72 et 0,75.

Comparison of two methods for choosing repeatable control strategies for kinematically redundant manipulators, A

Includes bibliographical references.A kinematically redundant manipulator is a robotic system that has more than the minimum number of degrees of freedom that are required for a specified task. Due to this additional freedom, control strategies may yield solutions which are not repeatable in the sense that the manipulator may not return to its initial joint configuration for closed end effector paths. This paper presents two methods for choosing repeatable control strategies which minimize their distance from a non-repeatable inverse with desirable properties. The first method minimizes the integral norm of the difference of the desired inverse and a repeatable inverse. While this is the more appropriate criterion, it results in a difficult optimization. The second method, which minimizes the distance of the null vectors associated with the desired and the repeatable inverses, is somewhat easier to implement. As an illustrative example the pseudoinverse is approximated in a region of the joint space using both techniques.This work was supported by Sandia National Laboratories under contract number I8-4379B. Additional support was provided by the NEC Corporation and the TRW Foundation

Near-pseudoinverse control of kinematically redundant manipulators with the constraint of repeatability

Includes bibliographical references (pages 119-120).The issue of repeatability is addressed for a particular redundant manipulator. This particular manipulator is a planar three-link manipulator with two orthogonal, prismatic joints and a third revolute joint. This manipulator can be thought of as a mobile robot with one revolute joint. It is shown that pseudoinverse control has no stable surfaces for this robotic manipulator. A class of repeatable inverses is then derived. Finally the repeatable inverse which is closest in an integral norm sense to the pseudoinverse is found from this class

Calculation of repeatable control strategies for kinematically redundant manipulators

Includes bibliographical references (page 130).A kinematically redundant manipulator is a robotic system that has more than the minimum number of degrees of freedom that are required for a specified task. Due to this additional freedom, control strategies may yield solutions which are not repeatable in the sense that the manipulator may not return to its initial joint configuration for closed end-effector paths. This paper compares two methods for choosing repeatable control strategies which minimize their distance from a nonrepeatable inverse with desirable properties. The first method minimizes the integral norm of the difference of the desired inverse and a repeatable inverse while the second method minimizes the distance of the null vectors associated with the desired and the repeatable inverses. It is then shown how the two techniques can be combined in order to obtain the advantages of both methods. As an illustrative example the pseudoinverse is approximated in a region of the joint space for a seven-degree-of-freedom manipulator

A Feasibility Study on a Parallel Mechanism for Examining the Space Shuttle Orbiter Payload Bay Radiators

The goal of the project was to develop the necessary analysis tools for a feasibility study of a cable suspended robot system for examining the space shuttle orbiter payload bay radiators These tools were developed to address design issues such as workspace size, tension requirements on the cable, the necessary accuracy and resolution requirements and the stiffness and movement requirements of the system. This report describes the mathematical models for studying the inverse kinematics, statics, and stiffness of the robot. Each model is described by a matrix. The manipulator Jacobian was also related to the stiffness matrix, which characterized the stiffness of the system. Analysis tools were then developed based on the singular value decomposition (SVD) of the corresponding matrices. It was demonstrated how the SVD can be used to quantify the robot's performance and to provide insight into different design issues