Analysis of Sample Acquisition Dynamics Using Discrete Element Method

The analysis presented in this paper is conducted in the framework of the Ocean Worlds Autonomy Testbed for Exploration Research and Simulation (OceanWATERS) project, currently under development at NASA Ames Research Center. OceanWATERS aims at designing a simulation environment which allows for testing autonomy of scientific lander missions to the icy moons of our solar system. Mainly focused on reproducing the end effector interaction with the inherent terrain, this paper introduces a novel discrete element method (DEM)-based approach to determine forces and torques acting on the landers scoop during the sample acquisition process. An accurate force feedback from the terrain on the scoop is required by fault-detection and autonomous decision-making algorithms to identify when the requested torque on the robotic arms joints exceeds the maximum available torque. Knowledge of the terrain force feedback significantly helps evaluating the arms links structural properties and properly selecting actuators for the joints. Models available in literature constitute a partial representation of the dynamics of the interaction. As an example, Balovnev derived an analytical expression of the vertical and horizontal force acting on a bucket while collecting a sample as a function of its geometry and velocity, soil parameters and reached depth. Although the model represents an adequate approximation of the two force components, it ignores the direction orthogonal to the scoop motion and neglects the torque. This work relies on DEM analysis to compensate for analytical models deficiencies and inaccuracies, i. e. provide force and torque 3D vectors, defined in the moving reference (body) frame attached to the scoop, at each instant of the sample collection process. Results from the first presented analysis relate to the specific OceanWATERS sampling strategy, which consists of collecting the sample through five consecutive passes with increasing depth, each pass following the same circularlinear- circular trajectory. Data is collected given a specific scoop design interacting with two types of bulk materials, which may characterize the surface of icy planetary bodies: snow and ice. Although specifically concerned with the OceanWATERS design, this first analysis provides the expected force trends for similar sampling strategies and allows to deduce phenomenological information about the general scooping process. In order to further instruct the community on the use of DEM tools as a solution to the sampling collection problem, two more analyses have been carried out, mainly focused on reducing the DEM computation time, which increases with a decrease in particle size. After running a set of identical simulations, where the only changing parameter is the size of the spherical particle, it is observed that the resulting force trajectories, starting from a given particle size, converge to the true trend. It is deducible that a further decrease in size yields negligible improvements in the accuracy, while it sensibly increases computation time. A final analysis aims at discussing limitations of approximating bulk material particles having a complex shape, e. g. ice fragments, with spheres, by comparing force trends resulting in the two cases for the same simulation scenario

Validation of Sustainability Instrument for Developing and Maintaining Effective Information Systems Programs

Program sustainability has received considerable research attention in many fields. Buck (2015) describes a general framework for program sustainability. Although initially designed to address the long-term viability of non-profits, public agencies, and foundations, the model is general enough to be applicable to a wide range of program types. A sustainable program is essentially one that has a recognized identity, and the resources and support needed to carry out its mission and serve its constituents across time. Buck asserts that programs with such characteristics can attract and retain supporters, achieve mission-related outcomes, and attract persistent funding and resources. An alternative framework for program sustainability (the Sustainability Framework) has been proposed by Schell et al. (2013). This framework was developed to describe factors related the sustainability of public health programs. It identifies a set of organizational and contextual domains with a program’s sustainability capacity - its ability to maintain programming and its benefits over time. The organizational and contextual domains identified by the Sustainability Framework include environmental support, funding stability, partnerships, organizational capacity, program evaluation, program adaptation, communications, and strategic planning. In combination, Buck’s sustainability model and Schell et al.’s sustainability framework help to delineate what program sustainability encompasses. Both provide a system-oriented perspective on programs that stress the importance of program goals, stakeholders, and resources

The Impact of a Project Management Course on Student Perceptions of the Importance of Expertise Needed by Project Managers: An Empirical Assessment

Project management is an increasingly important subject in both practical and academic circles. Good project managers are in high demand and short supply. Pressure has been increasingly placed on universities to better prepare students for project management positions. The short supply of project managers has also motivated companies to take advantage of project management training and certification programs offered by the Project Management Institute (PMI). This paper assesses the impact of a project management course on student perceptions of the extent to which numerous areas of expertise contribute to project manager effectiveness. Perceptions of the importance of change management, PERT, CPM, and function point analysis demonstrated the greatest modification as the result of taking the course. Other areas of expertise that increased in experience as well as areas of expertise that decreased in importance in the minds of project management students are also identified

Computer Literacy and the Introductory Student: An Analysis of Perceived and Actual Knowledge of Computers and Computer Applications

This study was designed to address the perennial issue of the degree of computer knowledge acquired by students prior to enrolling in an introductory Computer Concepts course. High school students often take a computer course that includes computer applications (word processing, spreadsheets, database management systems and presentation software); for some students, formal instruction in such computer applications begins in middle school and informal instruction may begin much earlier. Despite the increasing prevalence of students who enter universities having completed at least one computing course, instructors of university-level introductory computer courses typically observe wide differences in the computing background and knowledge of students enrolled in their courses. To better assess these differences, 82 students enrolled in a Spring Semester 2003 Computer Concepts course voluntarily completed a computer literacy assessment test in an attempt to earn a high enough score to “test out” of the course. This paper provides an analysis of the students’ perceptions of their proficiency with software applications, prior course completed, their frequency and longevity of computer and Internet use, and their results on the “test out” exam

The University Pages Game: Gamified Use of the Linkedin Student & Alumni Tool to Enhance Student Understanding of the Role of Social Media in Building Social Capital

Like many other academic disciplines, gamified learning environments are increasing in IS education. Creating and using gamified learning experiences contributes to “flipped classrooms” and is widely viewed as a mechanism for increasing course engagement among millennial students. This paper describes the creation and use of a social media module for a MIS course that uses game elements to introduce students to LinkedIn’s Student and Alumni Tool and how it can be used to build social capital. Because LinkedIn Student & Alumni tool is relatively unknown among students, the social media module, which we call the University Pages Game, also provides instructors with a vehicle for illustrating precepts of the Unified Theory of Acceptance and Use of Technology (UTAUT)

Student Perceptions of Project Management: Comparing students’ start and end of course Perceptions of the importance of PM, PMBOK Categories, and Contributing Subject Areas

Institutions of higher education are receiving steady pressure to better prepare students for project management (PM) positions and therefore the value being placed on project management courses is increasing in higher education, especially in computing disciplines. IS curricula models specifically address PM courses and concepts. The need for appropriately skilled project managers has also motivated industries to take advantage of PM training and certification programs offered by the Project Management Institute (PMI, 2000). The Standish group indicates that CIOs believe that having an experienced project manager is a key factor in IT projects success. This investigation focuses on the perception of students on the overall importance of PM, the Project Management Body of Knowledge Areas (PMBOK), and knowledge of specific subject areas that contribute to the preparation of students for PM positions. Graduate and undergraduate PM students at a regional institution in the southeast were survey at both the start and end of their courses

Variations in the dynamic properties of structures: the Wigner-Ville distribution

The Wigner-Ville Distribution (WVD) is a promising method for analyzing frequency variations in seismic signals, including those of interest for structural monitoring. Nonlinearities in the force displacement relationship will temporarily decrease the apparent natural frequencies of structures during strong to moderate excitation, and earthquake damage can permanently change building stiffnesses. A Fourier Transform of a building record contains information regarding frequency content, but it can not resolve the exact onset of changes in natural frequency – all temporal resolution is contained in the phase of the transform. The spectrogram is better able to resolve temporal evolution of frequency content, but has a trade-off in time resolution versus frequency resolution in accordance with the uncertainty principle. Time-frequency transformations such as the WVD allow for instantaneous frequency estimation at each data point, for a typical temporal resolution of fractions of a second. We develop a mathematical foundation for analyzing the evolution of frequency content in a signal, and apply these techniques to synthetic records from linear and nonlinear FEM analysis (including plastic rotation and weld fractures). Our analysis techniques are then applied to earthquake records from damaged buildings