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<p> Many manual tasks such as those in surgical applications require a high degree of motor skills that can only be gained through extensive training. This thesis is concerned with the design and control of collaborative training virtual environments with haptic feedback for skills training. The term "collaborative training" refers to a scheme in which the trainee and the trainer operate in a shared virtual environment. They collaboratively carry out the intended tasks using a shared "virtual tool". In order to enhance the trainee's motor skills, the conventional visual feedback will be augmented by force feedback providing the feel of the task environment as well as active guidance by the expert trainer.</p> <p> First, a set of psychophysics experiments are designed to investigate the usefulness of haptic-enabled collaborative virtual environments for motor skills training. Eighteen volunteers randomly divided between two training and control groups have participated in the experiments. The training group would undergo a number of collaborative training sessions with active help from the trainer whereas the control group would try the task on their own to achieve a set of stated goals. Each of the experiments is designed with specific performance objectives in mind, including trajectory tracking and task completion time. The results of the psychophysics experiments confirm that, when visual feedback is partially impaired, haptic-enabled collaborative training improves learning of a trajectory tracking task. In all the experimental scenarios tested, the results showed improvements in temporal response after receiving training.</p> <p> The second part of the thesis is devoted to the development of a general control framework for the coordination of the users in haptic-enabled collaborative virtual environments. The haptic interface control design is separated from the virtual environment simulation in order to provide more versatility in control strategies for both impedance and admittance-type virtual environments. Adaptive nonlinear controllers are proposed that establish desired linear-time-invariant and/or nonlinear static mappings amongst the users and the virtual task environment positions and forces. These controllers account for the nonlinear model of haptic devices and can handle uncertainties in the haptic devices, the users, and the virtual environment dynamics. First, the tracking behavior of the system is shown via a Lyapunov analysis. Then using a priori known bounds on user and environment parameters, the robust stability of the system is analyzed by employing the Nyquist envelops of interval plants and an off-axis circle criterion. The robust stability analysis provides bounds on the parameter of the linear and nonlinear mappings within which the stability of the system is guaranteed, for all possible system parameters with their a priori given bounds. Experiments carried out with two similar Quanser twin-pantograph haptic devices confirm the effectiveness of the proposed controllers in achieving the performance and stability objectives.</p> / Thesis / Master of Applied Science (MASc)

Yes / Purpose- Research on entrepreneurial orientation (EO) has concluded a positive link between EO and firm performance and that relationship depends on several contingencies. The paper derives insights from the absorptive capacity and contingency perspectives to introduce extraorganizational advice as a moderator of the relationship between EO and firm performance in a dynamic environment. Design/methodology/approach-Using survey data from 340 small and medium-sized enterprises (SMEs) in Ghana, the study examines the moderating influence of extraorganizational advice on the EO-firm performance relationship in dynamic environments. Findings-The study’s empirical findings suggest that extra-organizational advice amplifies the EO-performance relationship in dynamic environments. Research limitations/implications-The cross-sectional design of the study does not permit causal inferences to be made regarding the variables examined. Future studies may use longitudinal design to examine the causal links of the variables. Limitations aside, the study helps to answer how extra-organizational advice translates EO into improved performance in an environment characterised by constant flux. Practical implications- The results of this paper can assist entrepreneurs and policy-makers in understanding the dynamics and processes involved in implementing a strategic orientation to achieve higher performance. For SME managers, firm performance is determined by high levels of EO and extra-organizational advice in dynamic environments. The understanding of this issue can promote the development and maintenance of entrepreneurial ventures. Originality/value-The paper examines an important, but under-researched issue-the moderating effect of extra-organizational advice on the EO-performance relationship in dynamic environments. To the best of the authors’ knowledge, the present study pioneers research in this area.

To fulfill the objective of providing robust and reliable fiber optic pressure sensors capable of operating in harsh environments, this dissertation presents the detailed research work on the design, modeling, implementation, analysis, and performance evaluation of the novel fiber optic self-calibrated interferometric/intensity-based (SCIIB) pressure sensor system. By self-referencing its two channels outputs, for the first time to our knowledge, the developed SCIIB technology can fully compensate for the fluctuation of source power and the variations of fiber losses. Based on the SCIIB principle, both multimode and single-mode fiber-based SCIIB sensor systems were designed and successfully implemented. To achieve all the potential advantages of the SCIIB technology, the novel controlled thermal bonding method was proposed, designed, and developed to fabricate high performance fiber optic Fabry-Perot sensor probes with excellent mechanical strength and temperature stability. Mathematical models of the sensor in response to the pressure and temperature are studied to provide a guideline for optimal design of the sensor probe. The solid and detailed noise analysis is also presented to provide a better understanding of the performance limitation of the SCIIB system. Based on the system noise analysis results, optimization measures are proposed to improve the system performance. Extensive experiments have also been conducted to systematically evaluate the performance of the instrumentation systems and the sensor probes. The major test results give us the confidence to believe that the development of the fiber optic SCIIB pressure sensor system provides a reliable pressure measurement tool capable of operating in high pressure, high temperature harsh environments. / Ph. D.

The problem of rough surface scattering and propagation over rough terrain in ducting environments has been receiving considerable attention in the literature. One popular method of modeling this problem is the parabolic wave equation (PWE) method. In this method, the Helmholtz wave equation is replaced by a PWE under the assumption of predominant forward propagation and scattering. The resulting PWE subjected to the appropriate boundary condition(s) is then solved, given an initial field distribution, using marching techniques such as the split-step Fourier algorithm. As is obvious from the assumption on which it is based, the accuracy of the PWE approximation deteriorates in situations involving appreciable scattering away from the near-forward direction, i.e. when the terrain under consideration is considerably rough. The backscattered field is neglected in all PWE-based models. An alternative and more rigorous method for modeling the problem under consideration is the boundary integral equation (BIE) method, which is formulated in two steps. The first step involves setting up an integral equation (the magnetic field integral equation, MFIE, or the electric field integral equation EFIE) governing currents induced on the rough surface by the incident field and solving for these currents numerically. The resulting currents are then used in the appropriate radiation integrals to calculate the field scattered by the surface everywhere in space. The BIE method accounts for all orders of multiple scattering on the rough surface and predicts the scattered field in all directions in space (including the backscattering direction) in an exact manner. In homogeneous media, the implementation of the BIE approach is straightforward since the kernel (Green's function or its normal derivative) which appears in the integral equation and the radiation integrals is well known. This is not the case, however, in inhomogeneous media (ducting environments) where the Green's function is not readily known. Due to this fact, there has been no attempt, up to our knowledge, at using the BIE (except under the parabolic approximation) to model the problem under consideration prior to the work presented in this thesis. In this thesis, a closed-form approximation of the Green's function for a two-dimensional ducting environment formed by the presence of a linear-square refractivity profile is derived using the asymptotic methods of stationary phase and steepest descents. This Green's function is then modified to more closely model the one associated with a physical ducting medium, in which the refractivity profile decreases up to a certain height, beyond which it becomes constant. This modified Green's function is then used in the BIE approach to study low grazing angle (LGA) propagation over rough surfaces in the aforementioned ducting environment. The numerical method used to solve the MFIE governing the surface currents is MOMI, which is a very robust and efficient method that does not require matrix storage or inversion. The proposed method is meant as a benchmark for people studying forward propagation over rough surfaces using the parabolic wave equation (PWE). Rough surface scattering results obtained via the PWE/split-step approach are compared to those obtained via the BIE/MOMI approach in ducting environments. These comparisons clearly show the shortcomings of the PWE/split-step approach. / Ph. D.

The unequal distribution of gains from technology between favorable and unfavorable rice environments in Asia can widen if future transgenic rice varieties cannot be adopted in less favored regions. This study investigates the potential economic impacts of three transgenic rice technologies: stemborer resistance, for favorable irrigated environments; drought resistance, for unfavorable non-irrigated environments; and herbicide resistance, which can potentially benefit any of the environments but can only be adopted in areas under direct seeding. Specifying individual technologies contributes to a better comparative assessment of impacts from transgenic rice. The simulation uses a modified version of the Global Trade Analysis Project (GTAP) model with several innovative features: the database and code represent the distinct rice environments for both paddy and seed sectors; monopoly power is included in the model as a markup tax instrument when private firms sell herbicide resistant rice seed; and private rents can be transferred between regions and change income computation in the model. Equivalent variation measures obtained from simulations are similar at 2.3 billion, 2.5 billion and 2.2 billion dollars for stemborer, drought and herbicide resistance respectively. All technologies increase global rice output and reduce rice prices, while keeping labor wages at stable levels. Private provision of herbicide resistance rice generates benefits of 2.05 billion dollars while creating 122 million dollars in private profits. Although profits increase with higher markups, there are still large social benefits to realize from herbicide resistance technology. However, producers' response to reduced profitability is not accounted for and adoption is an exogenous variable in the model. The results suggest that the large expected impact from drought resistant rice supports public research investment on this technology. Joint efforts between public and private research sectors can increase the probability of success, and mechanisms to promote private research for unfavorable environments should be developed. Public policies should also remove obstacles that prevent firms from undertaking joint research with the public sector. Outcomes from public research, such as improved germplasm and spread of direct seeding techniques, also benefit the private sector and should act as an incentive for firms to build strategic alliances. / Ph. D.

Virtual environments are visually dominant systems. It seems that individuals" visual perception abilities would have an effect on their performance in a virtual environment. One such visual perception ability that seems a logical fit for study in virtual environments is that of disembedding ability. Disembedding ability is one part of a greater psychological construct known as field dependence. This research investigates how the learner characteristic of field dependence affects learning outcomes in virtual environments In order to examine the effect of virtual environments on recall among learners of differing levels of field dependence, the following specific questions and hypotheses were formed: 1) Does the use of virtual environments affect participants" performance in a task of recall? 2) Do participants of different levels of field dependence perform differently on a task of recall when presented with virtual environments versus static images? 3) Do field-dependent participants score higher on a test of recall when presented with a virtual environment? An experimental design using a sample of Virginia Tech students was employed in this study. The analysis consisted of a 2 X 2 factorial design with main effects for two levels of field dependence (field dependent and field independent), two levels of image representation (virtual environment versus static images), and interaction effects between the two factors. The factorial analysis showed no significant difference in recall test scores for the two treatments. Likewise, there was no significant difference in test scores for field dependent participants who received the virtual-environment treatment versus the static-image treatment. However, a significant interaction existed between field dependence and treatment type, favoring the field-independent participants who received the virtual-environment treatment. It can be concluded from this study that virtual environments have no effect on the recall ability of field-dependent learners. Further research might focus on other individual differences, such as spatial ability, that may have an effect on field-dependent learners" strategies for working in a virtual environment. / Ph. D.

Based upon the principles of equality, respect, and dignity for an organization and its community, Robert K. Greenleaf (1977) dedicated his life to conceptualizing and defining the humanistic philosophy of "servant leadership." With service and leadership sometimes seen as opposites, servant leaders are often misunderstood and perhaps underestimated. The purpose of this study was to create a well-defined comprehensive portrait of a servant leader by identifying key descriptors of the characteristics and behaviors of servant leaders and the work environments where they are effective. The research procedure consisted of a three-round Delphi to gain consensus on responses to four key research questions. From your experience and observation, what are the key words or phrases that describe (1) the characteristics that distinguish servant leaders, (2) the behaviors that distinguish servant leaders, (3) the work environments in which servant leaders are effective, and (4) the work environments in which servant leaders are ineffective? The following groups were represented on the panel of experts: (a) appointed and elected officials, (b) authors, (c) business leaders, (d) clergy, (e) educators, (f) leaders of associations, and (g) leaders of volunteer organizations. The first round Delphi instrument was open-ended. The second round gained opinion by adding a Likert scale to the results of the first round. The third round Delphi instrument was used to gather opinions from each panel member using a revised Likert scale instrument. In the third round each panelist received the statistical information calculated from the second round. The characteristics, behaviors, and effective work environments, as agreed upon consensually by the panel of experts in the third round, were reported. Twenty-eight panelists participated in each of the three rounds of the Delphi study. The characteristics, behaviors, and effective work environments of servant leaders, as determined by the panel of experts, are presented and discussed. A Servant Leadership Inventory was created from the data. The self-rating inventory is offered as an instrument to create discussion and increase awareness about leadership based on service to others. / Ed. D.

Smart homes, equipped with sensing, actuation, communication, and computation capabilities, enable automation and adaptation according to the occupants' needs. These capabilities work together to build holistic spatial and living experiences for the occupants. Smart technologies significantly impact spatial experiences, making smart home design an architectural problem along with a technological problem. Nevertheless, smart home research focuses primarily on standalone technological solutions, where the spatial/architectural aspect is largely absent. We argue that addressing the technological aspects isolated from the spatial context leads to reduced experiences for the users/occupants, as this practice blocks the pathways to develop holistic and innovative smart home solutions. Hence, we focus on bridging the gap between architectural and technological components in smart home research. To this end, we studied the design of smart homes from related disciplines, i.e., architecture, human-computer interaction, human--building interaction, industrial manufacturing, and modular assembly. Our research used the triangulation technique to consult with subject matter experts (researchers, practitioners, and professors of related disciplines) to understand current design processes. We conducted ethnographic studies, focus group studies, and in-depth interviews and identified challenges and best practices for smart home design process. Our investigation recognizes a nascent research problem where the technological and architectural aspects come together in the design thinking of smart home designers. We expanded the scope of design thinking to include three primary elements of smart homes- embedded technology, architectural elements, and occupants' needs. This multidisciplinary and complex process requires a well-defined design framework to methodically address all the issues associated with it. Hence, we developed a user-centered design framework, ArTSE, through an iterative Delphi study to guide the smart home design process. ArTSE stands for "Architecture and Technology in Smart Home DEsign". This framework guides user requirements collection using HCI models, technology decision making, interaction modalities selection, the decision support system for schematic design, technology infrastructure development, and production of the necessary documentation. This framework is an evolution of the normative theory in the architectural design process that caters to the needs of smart home design. For defining implementation strategies, we applied the framework to a case study-- a smart reconfigurable space design project. Overall, we document different aspects of the smart home design process and provide a comprehensive guideline for designers, researchers, and practitioners in this area. / Doctor of Philosophy / Smart homes have automation systems so that occupants can monitor and control lighting, heating, electronic devices, etc. remotely using phones/computers. Smart home devices and components are equipped with sensing, actuation, communication, and computation capabilities, to enable automation and adaptation according to the occupants' needs. These capabilities work together to build holistic spatial and living experiences for the occupants. Smart technologies significantly impact spatial experiences, making smart home design an architectural problem along with a technological problem. Nevertheless, smart home research focuses primarily on standalone technological solutions, where the spatial/architectural aspect is largely absent. We argue that addressing the technological aspects isolated from the spatial context leads to reduced experiences for the occupants, as this practice blocks the pathways to develop innovative smart home solutions. Hence, we focus on bridging the gap between architectural and technological components in smart home research. To this end, we studied the design of smart homes from related disciplines, i.e., architecture, human-computer interaction, human--building interaction, industrial manufacturing, and modular construction. We consulted with subject matter experts (researchers, practitioners, and professors of related disciplines) to understand current design processes. We conducted ethnographic studies, focus group studies, and in-depth interviews and identified challenges and best practices for smart home design process. Our investigation recognizes a nascent research problem where the technological and architectural aspects come together in the design thinking of smart home designers. We expanded the scope of design thinking to include three primary elements of smart homes- embedded technology, architectural elements, and occupants' needs. This multidisciplinary and complex process requires a well-defined design framework to methodically address all the issues associated with it. Hence, we developed a user-centered design framework, ArTSE, through an iterative procedure to guide the smart home design process. ArTSE stands for "Architecture and Technology in Smart Home DEsign". This framework guides user requirements collection using HCI models, technology decision making, interaction modalities selection, the decision support system for schematic design, technology infrastructure development, and production of the necessary documentation. For defining implementation strategies, we applied the framework to a case study-- a smart reconfigurable space design project. Overall, we document different aspects of the smart home design process and provide a comprehensive guideline for designers, researchers, and practitioners in this area.

Extended Reality (XR) is an upcoming field of technology that has garnered interest from researchers in the last few decades. This increased interest is largely due to the development of powerful hardware like the Microsoft HoloLens, Oculus Quest and the Magic Leap. Several companies like Microsoft, Meta Platforms, Apple and Nvidia are touting the rise of a new "metaverse'' - the next generation of the internet, that will blur the lines between physical and virtual presence. This thesis explores the use of web-based XR platforms in Computer-Supported Cooperative Work (CSCW) as an alternative to contemporary video conferencing tools. We conducted a user study with 15 subjects to evaluate web-based XR platforms (Mozilla Hubs) with video conferencing (Zoom) and examined subject attention and success in remote collaborative tasks. We also proposed a new system design to support embodied interactions in XR. This system was tested by measuring the communication latency between two collaborators separated by varying distances. Our system performance evaluation suggests the feasibility of support embodied interactions, with a minimal latency of 120ms across a distance of 4700 miles. / Master of Science / Extended Reality (XR) is changing the way we interact with digital content. In 2021, several companies like Microsoft, Meta Platforms, Apple and Nvidia are developing devices that allow users to physically interact with virtual content in 3-dimensional space. These technologies bring with them the promise of better remote communication and collaboration. Users will be able to enter these 3d virtual spaces as avatars and will be able to interact with digital media just like they would with real world objects. This thesis explores the use of web-based XR platforms in supporting remote collaboration as an alternative to contemporary video conferencing tools. We conducted a user study with 15 subjects to compare differences in web-based XR platforms (Mozilla Hubs) with video conferencing (Zoom). We proposed and evaluated a new system design to support more natural and intuitive interactions in XR. This system was tested by measuring the communication latency between two collaborators separated by varying distances. Our system performance evaluation suggests the feasibility of support embodied interactions, with a minimal latency of 120ms across a distance of 4700 miles.