In recent years Stewart platforms have been increasingly studied and developed. These parallel manipulators offer a number of advantages over traditional serial manipulators including high rigidity, good positioning accuracy and high load to weight ratio. The main disadvantage associated with parallel manipulators is that they have relatively limited workspaces. Numerous researchers have thus emphasized the need to develop refined methods for the determination of workspaces of such manipulators. This study is primarily concerned with extensions to a novel optimization approach for the determination of manipulator accessible output sets. The optimization approach provides a general method for the determination of workspaces of both serial and parallel manipulators and has the considerable advantage that it may easily be automated. Furthermore, the approach allows for the easy and systematic implementation of various physical constraints acting on manipulators. Established methods for workspace determination are reviewed and illustrated by application to a simple two degree of freedom example. The original optimization approach is extended and generalize< to enable the determination of non-convex workspaces. Simply stated, the approach consists of finding the points of intersection of the workspace boundary with a number of successive search elements. The points of intersection are determined by means of optimization techniques in which a dynamic constrained optimization algorithm is used. Two new methodologies, the modified ray method and the chord method, are proposed. Differences between these methods are illustrated using a simple example. The optimization approach, embodied in the proposed methodologies, is applied to the determination of workspaces of planar Stewart platforms of varied designs. A formulation for all constraints acting on planar Stewart platforms is introduced and implemented in the optimization approach. A special case of manipulator geometry, where the orientation of the platform is effectively redundant in determining the extreme reach of the manipulat'1r, is identified and studied. A slight modification to the optimization methodologies is introduced to allow for the determination of workspaces of such redundant manipulators. The modified ray and chord methods proposed in this study have proven capable of determining convex and non-convex manipulator workspaces. Of the two new methods, the chord approach is the most reliable in determining non-convex workspaces. Both optimization methodologies have been implemented in practical interactive computer systems, which allow for the easy determination of workspaces of planar Stewart pla1 forms of arbitrary geometry. / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted

The thesis deals with the contamination of the workspace with a liquid aerosol, which is generated by scattering and evaporation of the cooling fluid. Cooling fluid are primarily intended to lubricate, cool and clean the tool and the workpiece, but the unwanted side effect is the formation of a liquid aerosol that holds in the air of the workspace. In such a contaminated work environment, the operator is exposed to a certain dose of a liquid aerosol that causes dermatological and respiratory problems. The topic of the thesis was to find out the number of particles of liquid aerosol that arises under varying working conditions and its dispersion in space. This amount was determined by image analysis using a high-speed camera.

This thesis reports on a pilot project which was developed to meet the needs of specific research groups for a collaborative workspace. The main components of the project include a digital library, online discussion forum, adaptive hypermedia engine and a statement database. Such a system was deemed necessary because of today's global network of researchers who are divided by both location and time. The need therefore exists for a system which allows researchers to work on a project without the need to be in the same physical location. Such a system is called an online collaborative workspace. An online collaborative workspace allows researchers to work together on projects by providing various means of sharing information and resources. The main research question addressed in this study is:  What are the user requirements and design specifications of an online collaborative workspace developed in open source software? In order to answer this main question, the following sub-questions need to be addressed:  What are the main design principles and functionalities of such a collaborative workspace?  How can they be integrated in developing a modular open source framework?  To what extent can such a framework be customised for implementation in new or existing collaborative projects?  What are the usability requirements of such an online collaborative workspace and how should one go about to test the usability of such a framework? Before being able to accurately determine the user requirements of an online collaborative workspace, we first need to determine which features exist in current systems. The main question driving the literature survey therefore is:  What are the main components of current online collaborative workspaces as reported in the literature? Chapter 2 of this report is devoted to identifying and researching the various components that define an online collaborative workspace. Each of these components are investigated in detail by means of informal interviews as well as a literature survey. The components that were identified include a digital library, online discussion forum and collaborative workspace. In addition to identifying the various components, this chapter also addresses the motivation for the use of open source software and the importance of usability. With the information obtained in chapter 2, chapter 3 sets out to develop a framework which addresses each of the components that were identified. The various features and properties of each component were identified and decisions were made with regard to the best method of implementation. In addition to the components that were developed, this chapter also focuses on various design implications such as modularity and the use of open source software. Chapter 4 describes the various projects where the framework was implemented. For each of the projects the user requirements, customisations and usability issues are addressed. This chapter highlights the framework's ability to be customised to suit the diverse needs of research projects. The final chapter provides a set of conclusions summarising how the main objectives of the study were addressed. Moreover, the limitations of the study are addressed and an outline is provided as to how these limitations are to be addressed in future work. / Dissertation (MIS (Multimedia))--University of Pretoria, 2008. / Information Science / unrestricted

Online consolidation fiber placement is emerging as an automated manufacturing process for the fabrication of large composite material complex structures. While traditional composite manufacturing techniques limited the products' size, geometrical shapes and laminate patterns, robotic automation of the fiber placement process allows the manufacture of complex bodies with any desired surface pattern or towpreg's direction. Therefore, a complete understanding of the robot kinematic capabilities should be made to accurately position the structure's substrate in the workcell and to compute the feasible product dimensions and sizes. A Matlab algorithm is developed to verify the feasibility of straight-line trajectory paths and to locate all valid towpreg segments in the workspace, with no focus on optimization. The algorithm is applied preliminary to a three-link planar arm; and a 6-dof Merlin robot is subsequently considered to verify the towpreg layouts in the three-dimensional space. The workspace is represented by the longest feasible segments and plotted on parallel two-dimensional planes. The analysis is extended to locate valid square areas with predetermined dimensions. The fabrication of isotropic circular coupons is then tested with two different compaction heads. The results allow the formulation of a geometric correlation between the end-effector dimensional measures and the orientation of the end-effector with respect to the towpreg segments. / Master of Science

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The need for online remote working from home significantly increased due to the COVID-19 pandemic. This unexpected crisis forced individuals and organizations to rapidly transition from face-to-face training to remote learning at home. This switch happened overnight and was not optional but necessary. Employees had to adapt to new online learning techniques, seeking to preserve the same level of learning as working from the office. The study participants were male and female remote workers in the United States aged 18 and over. A questionnaire focused on evaluating online training in the workplace and a survey measuring two types of attitudes related to the transfer of training and technology integration while taking online training courses that were distributed online. The study collected a total of 50 responses from participants for analysis. According to the study results, employees noted some positive features of remote learning, such as flexibility, self-paced learning opportunities, and faster content absorption. Areas employees identified for improvement were closely related to the causes of complaints, such as network and technology issues, using a learning management system (LMS), instructions for using an LMS or course management system (CMS), face-to-face tech support, distractions, and suitable workspace at home. The study's results revealed a need to design and improve an effective emergency remote training system that maintains remote learning similar to traditional classroom training and opportunities for non-co-located workers to prepare for future emergencies.

The Multi-Appendage Robotic System (MARS) built for this research is a hexapod robotic platform capable of walking and performing manipulation tasks. Each of the six limbs of MARS incorporates a three-degree of freedom (DOF), kinematically spherical proximal joint, similar to a shoulder or hip joint; and a 1-DOF distal joint, similar to an elbow or knee joint. Designing walking gaits for such multi-limb robots requires a thorough understanding of the kinematics of the limbs, including their workspace. The specic abilities of a walking algorithm dictate the usable workspace for the limbs. Generally speaking, the more general the walking algorithm is, the less constricted the workspace becomes. However, the entire limb workspace cannot be used in a continuous, statically stable, alternating tripedal gait for such a robot; therefore a subset of the limb workspace is dened for walking algorithms. This thesis develops MARS limb workspaces in the knee up conguration, and analyzes its limitations for walking on planar surfaces. The workspaces range from simple 2D geometry to complex 3D volumes. While MARS is a hexapedal robot, the tasks of dening the workspace and walking agorthm for all six limbs can be abstracted to a single limb using the constraint of a tripedal, statically stable gait. Based on understanding the behavior of an individual limb, a walking algorithm was developed to allow MARS to walk on level terrain. The algorithm is adaptive in that it continously updates based on control inputs. Open Tech developed a similar algorithm, based on a 2D workspace. This simpler algorithm developed resulted in smooth gait generation, with near-instantaneous response to control input. This accomplishment demonstrated the feasibility of implementing a more sophisticated algorithm, allowing for inputs of all six DOF: x and y velocity, z velocity or walking height, yaw, pitch and roll. This latter algorithm uses a 3D workspace developed to aord near-maximum step length. The workspace analysis and walking algorithm development in this thesis can be applied to the further advancement of walking gait generation algorithms. / Master of Science

Organizations strategically design the physical work environment to enhance employees' creativity. Understanding the impact of workspace layout on individual perceptions of creativity across generational cohorts can be vital to sustaining organizational competitiveness. Researchers have theorized that workspace layout affects employees' perceptions of creativity; however, few studies have looked at the effect of generational cohort on this relationship. A quantitative study was conducted to examine the effect of workspace layout on individual perceptions of creativity across generational cohorts. A sample of 162 participants completed an online demographics questionnaire as well as aKEYS, a modified version of the KEYS to Creativity and Innovation instrument. An ANOVA was used to determine whether generational cohort and workspace layouts affected the participants' individual perceptions of creativity. Results did not support the theory that workspace layout and generational cohort affected individual perceptions of creativity. However, these nonsignificant results can be used strategically by organizations to design physical workspaces that foster individual perceptions of creativity in order to attract and retain a diverse workforce by accommodating employees equally rather than on generational cohort membership. Social change implications are that the results can provide organizations with an understanding of ways in which they can effectively treat and meet the needs of the workforce as a whole, rather than develop strategies based on generational cohort membership.

Corporate Real Estate (CRE) investors are often confronted with a need for flexibility in buildings. They often embark on costly renovations to accommodate changing use requirements. When new needs arise, landlords and tenants often risk loss due to inability to easily switch to configurations that can meet those needs. The main cause for this problem is lack of a planning model that can allow buildings to easily evolve over time allowing decision-makers to hedge investment positions against risk due to uncertainty. The emergence of Real Options (RO) theory in the 1970's has led to debates in search of a better planning model for real projects. The success of RO application in building construction (BC) hinges on the development of models that can be used to assess economic performance of flexible design options (FDO) in building systems. For building interior spaces, there is currently no model that can value flexibility of partition systems. The purpose of this study is to present a model that can be used to value flexibility in mutually exclusive partition systems over a project's life span. The proposed model uses decision tree representation, stochastic forecasting and random sampling of decision-path scenarios to generate cumulative risk profiles of partition systems' life cycle costs with expected median value, standard deviation and variance to inform decision making under uncertainty. The research processes include: assumptions, decision-making structure for identification of uncertain variable, model representation, spreadsheet programming, Monte Carlo simulation, and validation. The model will enable application of RO "in" BC projects.