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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.
1

MODELING, DESIGN, AND FABRICATION OF MAGNETIC HYDROGEL MICROROBOTS FOR ADVANCED FUNCTIONALITIES

Liyuan Tan (17850158) 01 February 2024 (has links)
<p dir="ltr">In the past decade, magnetic microrobots have gain lots of attention because of their potentials in biomedical applications, such as cell/tissue manipulation, biopsy, and drug delivery. Recent development on materials and microfabrication techniques also provide more opportunities for microrobots. Especially, the emergence of smart polymers that are responsive to environments like hydrogels has given microrobots an additional degree-of-freedom. In the meantime, the two-photon polymerization (TPP) microscale 3D printing technique has enable fabrication process that cannot be achieved easily by traditional microfabrication techniques. In general, the goal of the research presented in this dissertation is to use both hydrogels and TPP to realize novel microrobots with multiple advanced functionalities, including adaptive locomotion and micromanipulation, and modular microrobots capable of changing end-effectors for different modes of micromanipulation to facilitate the development of the field. </p><p dir="ltr">This dissertation can be divided into four main parts: (i) a proof-of-concept study on adaptive helical microrobots with finite element analysis (FEA) and dynamic calculation, (ii) material calibrations and property testing, (iii) a helical adaptive multi-material microrobot (HAMMR), and (iv) a modular microrobot achieved by a responsive mating component. A environment-responsive hydrogel is adopted here to realize the adaptive locomotion for helical microrobot and the responsive mating component for the modular microrobot. All microrobots fabricated in this dissertation are achieved by the combination of TPP and traditional photolithography techniques. </p><p dir="ltr">In part (i), FEA is applied with classic parameters for a proof-of-concept study of helical microrobot made of the classic hydrogel upon the stimulation of temperature. At different temperature, the hydrogel is going to deform and therefore the microrobot. Based on the geometrical parameters predicted by FEA before and after stimulations, dynamic calculations are then applied to predict the change of swimming performance accordingly. In part (ii), material calibrations have been done in order to realize a homogeneous material for testing (for oil-immersion mode). However, due to the limitation of the custom-built testing system, a different approach (dip-in mode) is adopted and the material properties are successfully obtained. In part (iii), two generations of HAMMRs are investigated. The first generation of HAMMR is prepared by the oil-immersion mode which shows a record-breaking swimmering velocity with the capability of adaptive locomotion. The second generation is obtained by the dip-in mode which provides the opportunities for combining FEA, dynamic calculation, and experiment to realize a comprehensive studied for such microrobot. Moveover, advances have been made to the microrobot with a functional end-effector for micromanipulation tasks. In part (iv), a modular microrobot is proposed and realized by the introduction of a responsive mating component. The responsive mating component provides a locking mechanism between different modules of the microrobot. The microrobot is able to change its end-effector to perform different types of tasks. </p><p dir="ltr">By using TPP to pattern microscale hydrogel structures, microrobots are able to be implemented with advanced functional structures. The helical microrobots capable of adaptive locomotion and micromanipulation, and the modular microrobot that can switch end-effectors for different applications are advances toward the next generation of microrobots. Moreover, a standardized method is proposed for adaptive helical microrobots towards future biomedical applications. Both the proposed helical microrobot and the modular microrobot show great potential for future application and we believe the development of these microrobots will facilitate the development of the field of microrobot.</p>
2

A phone application to provide advanced remote control functionality to an embedded systems product

Michel, Larry Ashley 05 January 2011 (has links)
With the increasing popularity of phone application development, a number of features have surfaced that enable users to utilize extended functionalities with their phone. With a single device, a user is now able to have access to the latest trends. As a result, functionalities from various products such as personal computers or GPS devices can now be accessible in one place. While this technology is evolving at a fast rate, it is the embedded technology and hardware that drive it which facilitate the innovative designs and solutions. At the other end of the spectrum of embedded systems, companies continue to maintain legacy products that use embedded chips programmed through their flash memory. With this perceived commitment to stay loyal to their older product designs, it has become rather cumbersome for such companies to stay current with the latest hardware and software trends. The result is higher costs to the customers for their high-end products. While the average user invests in newer and faster Google phones or iPhones, it is unlikely that the same can be said for commercial products such as a refrigerator or a ball machine. What if a development framework existed that allowed customers to have access to better user interfaces and functionalities over the lifetime of their product? In this Masters report, an innovative approach is discussed which demonstrates the latest mobile phone technology combined with an existing embedded device being applied to the conversion of a low-end tennis ball machine into an affordable high-end one. / text
3

Characterization of Electrode Materials for Aqueous-Based Electrochemical Capacitors Using Spectroscopy, the Boehm Titration and Spectroelectrochemistry

Goertzen, Sarah L. 26 July 2010 (has links)
In this research various techniques were used to study surface groups on carbon electrodes, including the spectroscopic techniques UV-Vis-NIR, FTIR, PAS, XPS and XAS, as well as the Boehm titration. The methods determined to give the best insight to the surface functionalities on the carbon were XPS, XAS and the Boehm titration. The Boehm titration methodology was standardized before use. An in situ method of examining surface groups using spectroscopy during electrochemistry was attempted. Spectroelectrochemistry is a useful way to gain information on how electrochemistry affects electrodes during experimentation; however, it was unsuccessful for the carbon used and remains to be developed. Polymerization of the copolymer of PANI and PPy as a potential electrode material for ECs was achieved by electrochemical cycling and was studied through spectroelectrochemical measurements. Overall, the research completed included the initial stages to studying electrodes for electrochemical capacitors using analytical, non-electrochemistry techniques in conjunction with electrochemistry.
4

Alternative rownstream roles for Ste2p and an α-arrestin in sacccharomyces cerevisiae mating

2014 November 1900 (has links)
Ste2p and Ste3p are well-characterized yeast pheromone G-protein Coupled Receptors (GPCR) those are involved in the signaling of mating responses that lead to cell fusion. Their signaling–associated interactions with G-protein/MAPK signal transduction machinery are well established, homologous to those in mammalian systems, and serve as a simplified model system in GPCR research. While the arrestin- mediated biased signaling mechanism of mammalian GPCR has not been discovered for the pheromone receptors, a recent demonstration of α-arrestins being involved in the internalization of the pheromone GPCR, Ste2p was reported. The present study was designed to reevaluate and extend the alternate functionality for pheromone receptors and to determine the role of yeast arrestins in the yeast mating. Specific residues in the TM6 of Ste2p exhibiting strong mating and constitutive MAPK signaling were combined and investigated in terms of their effect on MAPK signal transduction leading to cell cycle arrest as well as their impact on downstream mating projection formation and zygote formation events. Our findings indicate that Ste2p possess as specific residues that govern its relative bias for mediating MAPK signaling or mating events. Relative dose response experiments accounting for systemic and observation bias for these mutations yielded evidence of mutational-derived functional biases for Ste2p and further validated the alternate pheromone dependent functionalities for Ste2p. Further, arrestin knockout and knock-in studies showed that Art1 (Ldb19) is selectively involved in the regulation of zygote formation but not MAPK signal transduction following the binding of ligand to Ste2p receptors. In addition, ligand stimulated selective localization of Art1 (Ldb19) to the mating projection, implicating it in the regulation of downstream mating functionalities. Overall, while leaving the full mechanism of alternate/biased Ste2p signaling to be elucidated, these results highlight the possibility of continued relevance of the yeast pheromone-mating pathway as a simplified model for GPCR research in the context of arrestin-mediated biased GPCR signaling.
5

Reducing redundant functionalities of an application portfolio : Case study Swedish municipality

Kara, Vikesh, Paidi, Vijay Pratap January 2011 (has links)
Many government organizations consist of complex application portfolios with significant redundant functionalities and in order to run this portfolio, 80% of the IT budget is consumed by maintenance cost. Eliminating redundant functionalities improves efficiency, operational performance and decreases maintenance costs. A midsized Swedish municipality has a complex application portfolio with redundant functionalities, and this study aims to suggest actions for reducing redundant functionalities of citizen related applications. In order to identify redundant functionalities in a complex organization such as the government, all surrounding complexities need to be identified. Therefore, by performing a literature study, Application Portfolio Rationalization has been selected as an approach for reducing redundant functionalities. An online survey was conducted for gathering data about applications and the total response rate was 46.5%. The collected data was analyzed to identify complexities and applications with similar purpose and functions. Finally, actions were suggested for reducing redundant functionalities of applications by consolidating them with the “best-in-class” application, and implementing a central database for reducing redundant storage of data by the applications.
6

Simultaneous Energy Harvesting and Vibration Control via Piezoelectric Materials

Wang, Ya 20 March 2012 (has links)
This work examines a novel concept and design of simultaneous energy harvesting and vibration control on the same host structure. The motivating application is a multifunctional composite sandwich wing spar for a small Unmanned Aerial Vehicle (UAV) with the goal of providing self-contained gust alleviation. The basic idea is that the wing itself is able to harvest energy from the ambient vibrations along with available sunlight during normal flight. If the wing experiences any strong wind gust, it will sense the increased vibration levels and provide vibration control to maintain its stability. This work holds promise for improving performance of small UAVs in wind gusts. The proposed multifunctional wing spar integrates a flexible solar cell array, flexible piezoelectric wafers, a thin film battery and an electronic module into a composite sandwich structure. The basic design factors are discussed for a beam-like multifunctional wing spar with load-bearing energy harvesting, strain sensing and self-controlling functions. Three-point bending tests are performed on the composite sandwich structure for bending strength analysis and bending stiffness prediction under a given safety factor. Additional design factors such as the configuration, location and actuation type of each piezoelectric transducer are investigated for optimal power generation. The equivalent electromechanical representations of a multifunctional wing spar is derived theoretically, simulated numerically and validated experimentally. Special attention is given to the development of a reduced energy control (REC) law, aiming to minimize the actuation energy and the dissipated heat. The REC law integrates a nonlinear switching algorithm with a positive strain feedback controller, and is represented by a positive feedback operation amplifier (op-amp) and a voltage buffer op-amp for each mode. Experimental results exhibit that the use of nonlinear REC law requires 67.3 % less power than a conventional nonlinear controller to have the same settling time under free vibrations. Nonlinearity in the electromechanical coupling coefficient of the piezoelectric transducer is also observed, arising from the piezoelectric hysteresis in the constitutive equations coupling the strain field and the electric field. If a constant and voltage-independent electromechanical coupling coefficient is assumed, this nonlinearity results in considerable discrepancies between experimental measurements and simulation results. The voltage-dependent coupling coefficient function is identified experimentally, and a real time adaptive control algorithm is developed to account for the nonlinear coupling behavior, allowing for more accurate numerical simulations. Experimental validations build upon recent advances in harvester, sensor and actuator technology that have resulted in thin, light-weight multilayered composite sandwich wing spars. These multifunctional wing spars are designed and validated to able to alleviate wind gust of small UAVs using the harvested energy. Experimental results are presented for cantilever wing spars with micro-fiber composite transducers controlled by reduced energy controllers with a focus on two vibration modes. A reduction of 11dB and 7dB is obtained for the first and the second mode using the harvested ambient energy. This work demonstrates the use of reduced energy control laws for solving gust alleviation problems in small UAVs, provides the experimental verification details, and focuses on applications to autonomous light-weight aerospace systems. / Ph. D.
7

Development of Controlled Ring-Opening Polymerization of  O-Carboxyanhydrides

Zhong, Yongliang 27 October 2020 (has links)
The aim of my Ph.D. thesis is to summarize my research on the development of ring-opening polymerization (ROP) of O-carboxyanhydrides (OCAs) to synthesize functionalized, degradable polyesters. Biodegradable polyesters are promising alternatives to conventional petroleum-based non-degradable polyolefins and they are widely used in everyday applications ranging from clothing and packaging to agriculture and biomedicine. Commercially available polyesters, such as poly(lactic-co-glycolic acid), poly(lactic acid), and polycaprolactone, hydrolyze in physicochemical media. They have been approved by FDA and widely used for medical applications. However, the lack of side-chain functionality in polyesters and in corresponding monomers greatly plagues their utility for applications that demand physicochemical properties such as high stiffness, tensile strength and elasticity. Increasing efforts have been devoted to the introduction of pendant groups along the polymer chain in order to modify and modulate the physicochemical properties of polyesters and thereby to expand their applications. Over the last decade, OCAs have emerged as an alternative class of highly active monomers for polyester polymerization. OCAs are prepared from amino acids and thus have a richer range of side chain functionalities than lactone or lactide. Like lactones, OCAs can undergo ROP to obtain polyesters. Unfortunately, current ROP methods, especially those involving organocatalysts, result in uncontrolled polymerization including epimerization for OCAs bearing electron-withdrawing groups, unpredictable molecular weights (MWs), or slow polymerization kinetics. Based on our recent success of Ni/Ir photoredox catalysis allowing for rapid synthesis of high-MWs polyesters, we further explore new polymerization chemistry to use earth-abundant metal complexes to replace expensive rare-earth metal photocatalysts, and practice the polymerization in moderate and energy-efficient reaction conditions. This thesis introduces novel photoredox and electrochemical earth-abundant metal catalysts that overcome above difficulties in the ROP chemistry of OCAs, and allow for the preparation of stereoregular polyesters bearing abundant side-chain functionalities in a highly controlled manner. Specifically, various highly active metal complexes have been developed for stereoselective ROP of OCAs, either using light or electricity, to synthesize syndiotactic or stereoblock copolymers with different thermal properties. Additionally, simple purification protocols of OCAs have also been initially studied, which potentially paves the way to bulk production of functional monomers. In this thesis, I first describe newly-developed photoredox Co/Zn catalysts to achieve a controlled ROP of enantiopure OCAs under mild reaction conditions (Chapter 2). Such discovery is extended to the combination use of Co catalysts with various Zn/Hf complexes that enable stereoselective controlled ROP of racemic OCAs for the preparation of stereoregular polyesters (Chapter 3). The mechanistic studies of the aforementioned developments lead to the application of such a catalytic system in controlled electrochemical ROP of OCAs (Chapter 4). Such chemistry can also be translated to stereoselectively electrochemical ROP of racemic OCAs to either syndiotactic or stereoblock polyesters, allowing precise control of polyester's tacticity and sequence (Chapter 5). An overview future work has been summarized (Chapter 6). / Doctor of Philosophy / Polyesters are widely used in everyday applications ranging from clothing and packaging to agriculture and biomedicine. Different from conventional unrecyclable plastics, polyesters are usually biocompatible and biodegradable, and can be synthesized from renewable resources. A few commercially available polyesters have been approved by FDA and widely used for medical applications. However, their utility for applications that demand various mechanical and chemical properties is greatly limited by the lack of side-chain functional groups in polyesters and in their monomers—lactones. Increasing efforts have been devoted to the introduction of pendant groups along the polymer chain in order to modify and modulate the desired properties of polyesters and thereby to expand their applications. Over the last decade, O-carboxyanhydrides (OCAs) have emerged as an alternative class of highly active monomers for polyester polymerization. OCAs can be prepared from renewable source amino acids and thus have a richer range of side chain functional groups. Like lactones, OCAs can undergo ring-opening polymerization (ROP). Unfortunately, current ROP methods usually result in uncontrolled polymerization of OCAs including loss of stereoregularity, unpredictable molecular weights, or slow polymerization rate. To address the above-described polymer chemistry and materials challenges, I have been motivated to develop a new polymer chemistry knowledge base when starting my Ph.D. program. I was first involved in the development of a controlled photoredox polymerization of OCAs produces polyesters with various side chain functional groups. By using photoredox Ni/Zn/Ir catalysts, stereoregular high molecular weight polyesters can be synthesized from racemic OCAs in a rapid, controlled manner. However, this catalytic system has to be used at -20 °C despite so successful in preparing stereoblock polyesters. Encouraged by our recent success in this area, I started to work on the discovery of other transition metal complexes such as the Co complexes used in N-carboxyanhydride polymerization. Ultimately, innovative photoredox Co/Zn catalysts has been successfully developed, and applied to our protocol to achieve the controlled ROP of enantiopure OCAs under mild reaction condition (Chapter 2). The Co catalyst can replace both Ni and Ir in aforementioned photoredox system. Meanwhile, the combination of Co catalysts and various Zn/Hf complexes has also been developed to undergo photoredox ROP of racemic OCAs to efficiently produce polyesters with different microstructures (Chapter 3). Although photoredox ROP is an efficient method for synthesizing degradable polyesters, great decrease in photonic flux with the depth of the reaction medium makes it less energy efficient compared to electricity. Therefore, we then extended our protocol to electrochemical reaction, which is one of the most energy-efficient chemical reactions. The newly identified Co/Zn catalytic system can be activated by electric current to mediate rapid electrochemical ROP (eROP) of enantiopure OCAs, allowing for the synthesis of isotactic polyesters in a highly controlled manner (Chapter 4). Additionally, stereoselective eROP of racemic OCAs has been firstly achieved by using various combinations of Co and Zn/Hf complexes (Chapter 5). In summary, my research produces unique and transformative insights into the innovative photoredox and electrochemical ROP mediated by metal catalysts. Given the importance and versatility of biodegradable and biocompatible polyester materials, the chemistry invented by our team can be expected to serve as a new platform for various applications in material and biomedical engineering.
8

Game Audio in Audio Games : Towards a Theory on the Roles and Functions of Sound in Audio Games

Åsén, Rickard January 2013 (has links)
For the past few decades, researchers have increased our understanding of how sound functions within various audio–visual media formats. With a different focus in mind, this study aims to identify the roles and functions of sound in relation to the game form Audio Games, in order to explore the potential of sound when acting as an autonomous narrative form. Because this is still a relatively unexplored research field, the main purpose of this study is to help establish a theoretical ground and stimulate further research within the field of audio games. By adopting an interdisciplinary approach to the topic, this research relies on theoretical studies, examinations of audio games and contact with the audio game community. In order to reveal the roles of sound, the gathered data is analyzed according to both a contextual and a functional perspective. The research shows that a distinction between the terms ‘function’ and ‘role’ is important when analyzing sound in digital games. The analysis therefore results in the identification of two analytical levels that help define the functions and roles of an entity within a social context, named the Functional and the Interfunctional levels. In addition to successfully identifying three main roles of sound within audio games—each describing the relationship between sound and the entities game system, player and virtual environment—many other issues are also addressed. Consequently, and in accordance with its purpose, this study provides a broad foundation for further research of sound in both audio games and video games.
9

Functionality assessment of inventory management software for SME / Utvärdering av funktionaliteter i lagerstyrningssystem för SMF

Johansson, Markus, Harding, Robin January 2013 (has links)
For numerous companies today, one of the key elements for successful competing in the market is an optimized inventory management. Inventory management is about satisfying the customer need, while keeping the inventory costs as low as possible. This report discusses the functionality assessment of inventory management software for small to medium sized enterprises (SME). It is an investigation motivated by the fact that high-end inventory management solutions are becoming financially available for SME via the SaaS technology. The main question that this study aims to answer is therefore what functionalities and functionality characteristics in external high-end inventory management solutions enable competitive advantage for SME’s. A survey complimented by a number of interviews was conducted in order to gain a broad picture of what the SME’s need from these solutions. The answers obtained from the SME respondents were compared to relevant literature, and from that the conclusions were drawn. Furthermore, a QFD analysis was made to evaluate how well an existing high-end-solution matches the SME requests. The result of the study shows that there are many similarities between what the SME need and what the large companies need in terms of functionalities in these systems. However, the study also shows that, for optimal use, these functionalities must be delivered by the system developers in a way that is better suited for SME’s. / För många företag idag är en av nyckelkomponenterna för framgångsrik konkurrens på marknaden en optimerad lagerstyrning. Lagerstyrning handlar om att tillfredsställa kundernas behov samtidigt som lagerkostnaderna hålls så låga som möjligt. Den här studien utvärderar funktionaliteter i lagerstyrningsmjukvaror för små till medelstora företag. Det är en undersökning som är motiverad av det faktum att avancerade lagerstyrningssystem blir mer och mer finansiellt tillgängliga för små till medelstora företag via den så kallade molnteknologin. Huvudfrågan som detta examensarbete ämnar besvara är därför vilka funktionaliteter och funktionaliteters egenskaper i avancerade externa lagerstyrningssystem som möjliggör konkurrenskraft för små till medelstora företag. En enkät kompletterad av ett antal intervjuer genomfördes för att skapa en bred bild av vad de små till medelstora företagen behöver från dessa system. Svaren som erhölls från de undersökta företagen jämfördes med relevant litteratur och från detta har slutsatser dragits. Dessutom har en så kallad QFD-analys gjorts för att utvärdera hur bra en existerande system stämmer överens med vad de små och medelstora företagen efterfrågar. Resultatet av detta examensarbete är att det finns många likheter mellan vad de små till medelstora företagen behöver och vad de stora företagen behöver angående funktionaliteter i dessa system. Emellertid visar denna undersökning att, för optimal nytta av dessa system, måste dessa funktionaliteter anpassas för de små och medelstora företagen.
10

An analysis of new functionalities enabled by the second generation of smart meters in Sweden / Analys av nya funktioner möjliggjort av andra generationen smarta mätare i Sverige

Drummond, Jose January 2021 (has links)
It is commonly agreed among energy experts that smart meters (SMs) are the key component that will facilitate the transition towards the smart grid. Fast-peace innovations in the smart metering infrastructure (AMI) are exposing countless benefits that network operators can obtain when they integrate SMs applications into their daily operations.  Following the amendment in 2017, where the Swedish government dictated that all SMs should now include new features such as remote control, higher time resolution for the energy readings and a friendly interface for customers to access their own data; network operators in Sweden are currently replacing their SMs for a new model, also called the second generation of SMs. While the replacement of meters is in progress, many utilities like Hemab are trying to reveal which technical and financial benefits the new generation of SMs will bring to their operations.    As a first step, this thesis presents the results of a series of interviews carried out with different network operators in Sweden. It is studied which functionalities have the potential to succeed in the near future, as well as those functionalities that are already being tested or fully implemeneted by some utilities in Sweden. Furthermore, this thesis analyses those obstacles and barriers that utilities encounter when trying to implement new applications using the new SMs. In a second stage, an alarm system for power interruptions and voltage-quality events (e.g., overvoltage and undervoltage) using VisionAir software and OMNIPOWER 3-phase meters is evaluated. The results from the evaluation are divided into three sections: a description of the settings and functionalities of the alarm, the outcomes from the test, and a final discussion of potential applications. This study has revealed that alarm functions, data analytics (including several methods such as load forecasting, customer segmentation and non-technical losses analysis), power quality monitoring, dynamic pricing, and load shedding have the biggest potential to succeed in Sweden in the coming years. Furthermore, it can be stated that the lack of time, prioritization of other projects in the grid and the integration of those new applications into the current system seem to be the main barrier for Swedish utilities nowadays. Regarding the alarm system, it was found that the real benefits for network operators arrive when the information coming from an alarm system is combined with a topology interface of the network and a customer notifications server. Both applications could improve customer satisfaction by significantly reducing outage time and providing customers with real-time and precise information about the problems in the grid.

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