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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

NEW ENTERPRISE RESOURCE PLANNING IMPLEMENTATION IN THE SWEDISH LANDSCAPE : An explorative study of employees’ perspectives on Organizational Support and its barriers

Reis Siribeli, Rafael, Saval Sanchez, Andoni January 2023 (has links)
Date: 2024-01-04 Level: Bachelor thesis in Business Administration, 15 cr Institution: School of Business, Society and Engineering, Mälardalen University  Authors: Andoni Saval Sanchez Rafael Reis Siribeli  Title: New Enterprise Resource Planning Implementation in the Swedish Landscape.  Supervisor: Emre Yildiz  Keywords: Organization Support, Organizational Inertia, Enterprise Resource Planning, Information Systems  Research question: What are the primary organizational support actions that employees from different firms in Sweden claim to impact the most when adopting new technologies?  Purpose: The purpose is to explore how organizational support actions affect employees' adoption of Enterprise Resource Planning (ERP) systems in Sweden, analyzing their adaptation, behavioral intentions and firm’s actions, and providing recommendations for firms in the edge of implementing such systems.  Method: Qualitive research by using semi-structured interviews and Thematic Analysis.  Conclusion: The study was conducted by collecting primary data in two organizations located in Sweden who had recently experienced an ERP system implementation, guided by literature on Organizational Inertia and Organizational Support theories with a strong focus in employee perceptions. A thematic analysis of the data resulted in the following findings, 7 primary organizational support actions and 8 barriers were identified within 7 employees in the 2 firms. These were, in terms of Organizational Support, Teamwork, Words of Appreciation, Open Communication, Recognition, Trust and Honesty, Hyper Care Workshops with Stakeholders, and Roles and Responsibility. In term of barriers, Language, Time Constraint, Gap of Knowledge of Own Operations, Lack of Knowledge Transfer, Lack of Clarity in Roles, Unpreparedness, Lack of Human Resources, and Underwhelming Contractors. The authors hope these results can function as an aid to organizations experiencing a technological transformation and shade some light to the struggles employees face in the process.
142

Using Deep Neural Networks and Industry-Friendly Standards to Create a Robot Follower for Human Leaders

Gilliam, Austin Taylor 27 August 2018 (has links)
No description available.
143

Utilizing the Subfossil Record of Seagrass-Associated Mollusks to Reveal Recent Changes in Coastal Marine Environments

Feser, Kelsey M. 19 October 2015 (has links)
No description available.
144

Inertia Friction Welded Ni-Base Superalloys: Process Examination, Modeling and Microstructure

Mahaffey, David 30 September 2016 (has links)
No description available.
145

Human-Robot Interactive Control

Jou, Yung-Tsan January 2003 (has links)
No description available.
146

Vehicle Inertia Impact on Fuel Consumption of Conventional and Hybrid Electric Vehicles Using Acceleration and Coast Driving Strategy

Lee, Jeongwoo 15 October 2009 (has links)
In the past few years, the price of petroleum based fuels, especially vehicle fuels such as gasoline and diesel, has been increasing at a significant rate. Consequently, there is much more consumer interest related to reducing fuel consumption for conventional vehicles and hybrid electric vehicles (HEVs) than in the past. The goal of many competitions and challenges held in North America and Europe is to achieve extremely low fuel consumption. A possible strategy to reduce fuel consumption is to use the vehicle's fuel converter such as an engine to accelerate the vehicle to a high speed and coast to a lower speed with the engine off. This method will reduce fuel flow to zero during the coast phase. Also, the vehicle uses higher power engine load to accelerate to the upper vehicle speed in a limited time, thus increasing the engine brake thermal efficiency. This strategy is known as "pulse and glide" or "burn and coast" in some references. In this study, the "pulse and glide" (PnG) method is first applied to a conventional vehicle to quantify the fuel consumption benefits when compared to steady speed conditions over the same distance. After that, an HEV is used as well to investigate if a hybrid system can further reduce fuel consumption with the proposed strategy. Note that the HEV used in this study has the advantage that the engine can be automatically shut off below a certain speed (~40 mph) at low loads, however a driver must shut off the engine manually in a conventional vehicle to apply this driving strategy. In this document, three preliminary results of the PnG driving strategy are presented; (1) improved fuel economy for a conventional vehicle from a simple spread sheet model, (2) improved fuel economy for an HEV from a dynamic vehicle simulation model (the Powertrain Analysis Toolkit (PSAT)) and (3) improved fuel economy for an HEV from vehicle testing at Argonne National Laboratory (ANL), all compared to steady speed conditions. The preliminary results show that the impact of engine load and kinetic energy stored in vehicle inertia is significant for fuel consumption using a PnG driving strategy compared to steady speed driving at the same average speed case. Especially, fuel economy can be improved at low speed range and higher acceleration because the aerodynamic drag force is smaller at low speed and the engine is running in a more efficient region for a short period of time respectively. In the last section, proposed directions of research are addressed based on the preliminary results. / Ph. D.
147

From Oscillating Flat Plate to Maneuvering Bat Flight – Role of Kinematics, Aerodynamics, and Inertia

Rahman, Aevelina 01 February 2022 (has links)
With the aim to understand the synergistic roles played by kinematics, aerodynamics, and inertia in flapping wing maneuvers, this thesis first investigates the plunging motion of a simple flat plate as it is a fundamental motion in the kinematics of many flying animals. A wide range of frequency (k) and amplitude (h) is investigated to account for a robust kinematic characterization in the form of plunge velocity (kh). Leading Edge Vortices (LEVs) are found to be responsible for producing thrust while Trailing Edge Vortices (TEVs) produce drag. The vortex dynamics becomes nonlinear for higher kh and three main vortex-vortex interactions (VVI) are identified in the flow-field. To estimate the sole effect of LEVs on thrust coefficient, TEVs are eliminated by introducing a splitter plate. This resulted in reduced non-linearity in VVI and facilitated a parametrization of aerodynamic thrust coefficient with key kinematic features, frequency (k) and amplitude (h) [C_T= A.k^1.4 h-B where A and B are constants]. This is followed by investigating the more direct problem of bio-inspired MAV research – the interplay of kinematics, aerodynamics, and inertia on maneuvering bat flights. At first, an ascending right turn of a H. pratti bat is investigated to elucidate on the kinematic features and aerodynamic mechanisms used to effectuate the maneuver. Deceleration in flight speed, an increase in flapping frequency, shortening of the upstroke, and thrust generation at the end of the upstroke is observed during this maneuver. The turn is initiated by the synergisytic implementation of roll and yaw rotation where the turning moments are generated by drawing the inside wing closer to the body, by introducing phase lags in force generation between the two wings and by redirecting force production to the outer part of the wing outside of the turn. Upon comparison with a similar maneuver by a H. armiger bat, some commonalities as well as differences were observed. This analysis was followed by a comparative study among different maneuvering flights (a straight flight, two ascending right turns, and a U-turn) in order to establish the complete motion dynamics of a maneuver in action. The individual effects of aerodynamics and wing inertia for maneuvering flights of a H. armiger and H. pratti are investigated. It is found that for both, translation and rotation the overall trajectory trend is mostly driven by the aerodynamic forces and moments, whereas inertial effects drive the intricate intra-cycle fluctuations as well as the vertical velocity and altitude gain during ascent. Additionally, inertial moments play a dominant role for effecting yaw rotations where the importance of the Coriolis and centrifugal moments increase with increasing acuteness of the maneuver, with the largest effect of centrifugal moments being evidenced in the U-turn. / Doctor of Philosophy / The study of flapping wing is of paramount interest in the field of small aerial and aquatic vehicle propulsion. The intricate mechanisms acting behind a flapping wing maneuver can be explained by the synergistic roles played by 3 main components; details of the wing motion or the kinematics, how the air reacts to the wing motion or the aerodynamics, and the effort or force required to move the wings or wing inertia. This dissertation systematically reports the contribution of these components to a flapping flight maneuver. At first, the plunging motion of a simple flat plate is investigated as it is a fundamental motion in the flapping flight of many flying animals. A wide range of frequency and amplitude is investigated and their effect is characterized by a single parameter called "plunge velocity". It is found that, the resultant flow field becomes disorderly for higher plunge velocities which can be characterized by three different types of vortex interactions. The observed results facilitated a robust parametrization of aerodynamic thrust production with key kinematic features, frequency and amplitude. After this, the dissertation focuses on the bio-inspiration aspect of flapping flight by investigating the interplay of kinematics, aerodynamics, and inertia of maneuvering bat flights. At first, an ascending right turn of one species (H. pratti) is investigated to elucidate on the kinematic features and aerodynamic mechanisms used to effectuate the maneuver. Some characteristic features observed are – lowering of flight speed, increase in flapping rate, shortening of upstrokes, and generation of a forward force at the end of the upstroke. It is observed, that the bat turns by using synergistic body rotations in multiple directions which are effected by various techniques such as - drawing the wing inside the turn closer to the body, and changing the timing and location of the forces produced between the two wings. Upon comparison with a similar maneuver by a H. armiger bat, some commonalities as well as differences were observed in the maneuver mechanisms. This analysis was followed by a comparative study among different maneuvering flights (a straight flight, two ascending right turns, and a U-turn) to establish the complete motion dynamics of a maneuver. The individual contributions of aerodynamics and wing inertia for maneuvering flights of a H. armiger and H. pratti are investigated. It is found that for both, translation and rotation the overall trajectory is mostly influenced by the aerodynamic forces and moments, whereas inertial effects are responsible for trajectory fluctuations during a flapping cycle as well contributing to altitude gain during ascent for the H. armiger bat.
148

Inverter-based Control to Enhance the Resiliency of a Distribution System

Shrestha, Pratigya 18 September 2019 (has links)
Due to the increase in the integration of renewable energy to the grid, there is a critical need for varying the existing methods and techniques for grid operation. With increased renewable energy, mainly wind and photovoltaics, there is a reduction in inertia as the percentage of inverter-based resources is increasing. This can bring about an issue with the maintenance and operation of the grid with respect to frequency and voltage. Thus, the ability of inverters to regulate the voltage and frequency becomes significant. Under normal operation of the system, the ability of the inverters to support the grid frequency and voltage while following the grid is sufficient. However, the operation of the inverters during a resiliency mode, under which there is an extended outage of the utility system, will require the inverter functionality to go beyond support and actually maintain the voltage and frequency as done by synchronous machines, acting as the grid-forming inverter. This project focuses on the operation of grid forming sources based on the virtual synchronous generator to regulate the voltage and frequency in the absence of the grid voltage through decentralized control of the inverters in the distribution feeder. With the most recent interconnection standard for the distributed generation, IEEE-1547 2018, the inverter-based generation can be used for this purpose. The simulations are performed in the Simulink environment and the case studies are done on the IEEE 13 node test-feeder. / Master of Science / With the increase in the renewable energy sources in the present grid, the established methods for the operation of the grid needs to be updated due to the changes that the large amount of renewable energy sources bring to the system. Due to the While the conventional resources in the power system was mainly synchronous generators that had an inherent characteristic for frequency support and regulation due to the inertia this characteristic can be lacking in many of the renewable energy sources that are usually inverter-based. At present, the commonly adapted function for the inverters is to follow the grid which is suitable in case of normal operation of the power system. However, during emergency scenarios when the utility is disconnected and a part of the system has to operate independently the inverters need to be able to regulate both the voltage and frequency on their own. In this project the inverter-based control, termed as the virtual synchronous generator, has been studied such that it mimics the well-established controls for the conventional generators so that the inverter-based renewable resource appears similar to the conventional generator from the point of view of the grid in terms of the electrical quantities. The utilization of this type of control for operation of a part of the feeder with each inverter-based resource controlling its output in a decentralized manner is studied. The controls try to mimic the established controls for conventional synchronous machine and use it for maintain operation of the system with inverters.
149

Floor Vibrations: Girder Effective Moment of Inertia and Cost Study

Warmoth, Francis James 14 February 2002 (has links)
Studies on the effective moment of inertia of girders that support concrete slabs using joist seats as the horizontal shear connections, and a cost efficiency analysis comparing composite and non-composite floor systems that meet vibrations design standards, were conducted. The first study was undertaken because over-prediction of girder effective moment of inertia was the suspected cause of several recent vibration problems in floors supported by widely spaced LH-series joists. Eight purpose-built floors of the type in question were subjected to experimental tests of girder effective moment of inertia and girder frequency. Frequencies were tested for two live loading cases. Three separate test configurations were made with each floor by changing the seat-to-girder connections between bolted, welded, and reinforced. In the study, 1) the accuracy of the current design practice is assessed, 2) a new relationship was proposed, and 3) suggestions for finite element modeling are made. In recent years, composite construction has been used to improve cost efficiency by reducing structural weight and in some cases by reducing story height. However, vibration problems are a design consideration in composite floors because lighter floors tend to be more lively. It is not clear if cost savings can be made with composite construction if vibrations are considered in the design. To compare the cost of composite and non-composite floors that satisfy AISC/CISC Design Guide criterion for walking excitation, four typical size bays were analyzed using commercial design software that finds the least expensive member configuration for a given bay size. All acceptable bay configurations of member sizes and spacing were evaluated for least non-composite and composite costs, then these results were compared. The findings show that composite construction can be more economical when initial dead load deflections do not control the design. / Master of Science
150

Power System Parameter Estimation for Enhanced Grid Stability Assessment in Systems with Renewable Energy Sources

Schmitt, Andreas Joachim 05 June 2018 (has links)
The modern day power grid is a highly complex system; as such, maintaining stable operations of the grid relies on many factors. Additionally, the increased usage of renewable energy sources significantly complicates matters. Attempts to assess the current stability of the grid make use of several key parameters, however obtaining these parameters to make an assessment has its own challenges. Due to the limited number of measurements and the unavailability of information, it is often difficult to accurately know the current value of these parameters needed for stability assessment. This work attempts to estimate three of these parameters: the Inertia, Topology, and Voltage Phasors. Without these parameters, it is no longer possible to determine the current stability of the grid. Through the use of machine learning, empirical studies, and mathematical optimization it is possible to estimate these three parameters when previously this was not the case. These three methodologies perform estimations through measurement-based approaches. This allows for the obtaining of these parameters without required system knowledge, while improving results when systems information is known. / Ph. D. / Stable grid operations means that electricity is supplied to all customers at any given time regardless of changes in the system. As the power grid grows and develops, the number of ways in which a grid can lose stability also grows. As a result, the metrics that are used to determine if a grid is stable at any given time have grown increasingly complex and rely on significantly more amounts of information. This information required in order to obtain the metrics which determine grid stability often has key limitations in when and how it can be obtained. The work presented details several methods for obtaining this information in situations were it was previously not possible to do so. The methods are all measurement based, which means that no prior knowledge about the grid is required in order to compute the values.

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