Dissertations / Theses on the topic 'Force based design (FBD)'

Seismic design of standard structures is typically based on a force-based design approach. Over the years, this approach has proven to be robust and easy to apply by design engineers and – in combination with capacity design principles – it provided a good protection against premature structural failures. However, it is also known that the force-based design approach as it is implemented in the current generation of seismic design codes suffers from some shortcomings. One of these relates to the fact that the base shear is computed using a pre-defined force reduction factor, which is constant for a certain type of structural system. As a result of this, for the same design input, structures of the same type but different geometry are subjected to different ductility demands and show therefore a different performance during an earthquake. The objective of this research is to present an approach for computing force reduction factors using simple analytical models. These analytical models describe the deformed shape at yield and ultimate displacement of the structure and only require input data that are available when starting the design process, such as geometry and general material properties. The displacement profiles are obtained from section dimensions and section ductility capacities that can be estimated at the beginning of the design process. The so computed displacement ductility is taken as proxy of the force reduction factor. Such analytical models allow to link global to local ductility demands and therefore to compute an estimate of the force ductility reduction factors for wall and frame structures. Finally, this research develops an approach for frame-wall structures as combination of results obtained for wall and frame systems. The proposed method is applied to a set of frame-wall structures and validated by means of nonlinear time history analyses. Obtained results show that the proposed method yields a more accurate seismic performance than the current code design approach. The presented work therefore contributes to the development of revised force-based design guidelines for the next generation of seismic design codes.<br>La progettazione sismica di strutture è tipicamente basato su un approccio progettuale basato sulle forze. Nel corso degli anni, questo approccio ha dimostrato di essere robusto e facile da applicare dai progettisti e, in combinazione con il principio di gerarchia delle resistenze, fornisce una buona protezione contro i meccanismi di collasso fragili. Tuttavia, è anche noto che l'approccio di progettazione in forze così come attuato nell’odierna generazione di normative soffre di alcune carenze. Uno di questi riguarda il fatto che il tagliante alla base è calcolato utilizzando un fattore di struttura predefinito, cioè costante per tipo di sistema strutturale. Di conseguenza, per lo stesso input di progettazione, strutture dello stesso tipo ma diversa geometria sono sottoposti ad una diversa domanda di duttilità e mostrano quindi una diversa prestazione durante un evento sismico. L'obiettivo di questo studio è quello di presentare un approccio per il calcolo fattori di struttura utilizzando modelli analitici semplici. Questi modelli analitici descrivono la deformata a snervamento e spostamento ultimo della struttura e richiedono solo dati di input disponibili all’inizio del processo di progettazione, quali dati geometrici e proprietà dei materiali. La deformata della struttura ottenuta dalle dimensioni delle sezioni e la capacità in termini di duttilità sezionale possono essere stimati all'inizio della progettazione. La duttilità è alla base della formulazione del fattore di struttura come proposto dai modelli analitici presentati. Tali modelli analitici permettono di collegare le duttilità sezionali alla duttilità strutturale e quindi calcolare una stima del fattore di struttura per struttura a pareti e a telaio. Infine, si sviluppa un approccio per strutture duali di tipo telaio-parete come combinazione di risultati ottenuti per i sistemi singoli. Il metodo proposto è applicato ad un insieme di strutture duali e validato con analisi dinamiche non lineari. Si dimostra che il metodo proposto produce una più accurata prestazione sismica rispetto all'approccio progettuale delle normative odierne. Il lavoro presentato contribuisce pertanto allo sviluppo di nuove linee guida per la progettazione sismica nella prossima generazione di normative.

A compliant force/torque sensor for robot force control has been developed. This thesis presents methods of designing, testing, and implementing the sensor on a robotic system. The sensor uses an orthoplanar spring equipped with Hall-effect sensors to measure one component of force and two moment components. Its unique design allows for simple and cost effective manufacturing, high reliability, and compactness. The device may be used in applications where a robot must control contact forces with its environment, such as in surface cleaning tasks, manipulating doors, and removing threaded fasteners. The compliant design of the sensor improves force control performance and reduces impact forces. Sensor design considerations are discussed, followed by a discussion of the proposed design concept. Theoretical compliance and stress analysis of the orthoplanar spring is presented that allows for rapid design calculations; these calculations are validated via finite element analysis. A mechanical design method is given which uses the results of the compliance and stress analysis. Transducer design is then addressed by developing a model of the sensor. The design methods are used to design a prototype sensor which is tested to determine its instrument uncertainty. Finally, the sensor is implemented on a robotic platform to test its performance in force control.

The continuum design sensitivity analysis (CDSA) has been applied to the magnetostatic and electrostatic force calculation. This method allows the computation of the net loading force on a body as well as the force distribution on the surface of the body. An algorithm for force calculation combined with a standard field analysis software package is presented. The efficiency and accuracy of the method is proved through the numerical implementation applied to a set of test examples. In addition, the new approach has several advantages over the traditional methods based on the Maxwell Stress Tensor, such as no air gap or artificial interference with the original model is required. Particularly, the performance analysis of a MEMS micro-mirror using CDSA torque calculation is conducted for the first time.

The scale of engineering problems has sharply increased over the last twenty years. Larger coupled systems, increasing complexity, and limited resources create a need for methods that automatically decompose problems into manageable sub-problems by discovering and leveraging problem structure. The ability to learn the coupling (inter-dependence) structure and reorganize the original problem could lead to large reductions in the time to analyze complex problems. Such decomposition methods could also provide engineering insight on the fundamental physics driving problem solution. This work forwards the current state of the art in engineering decomposition through the application of techniques originally developed within computer science and information theory. The work describes the current state of automatic problem decomposition in engineering and utilizes several promising ideas to advance the state of the practice. Mutual information is a novel metric for data dependence and works on both continuous and discrete data. Mutual information can measure both the linear and non-linear dependence between variables without the limitations of linear dependence measured through covariance. Mutual information is also able to handle data that does not have derivative information, unlike other metrics that require it. The value of mutual information to engineering design work is demonstrated on a planetary entry problem. This study utilizes a novel tool developed in this work for planetary entry system synthesis. A graphical method, force-based clustering, is used to discover related sub-graph structure as a function of problem structure and links ranked by their mutual information. This method does not require the stochastic use of neural networks and could be used with any link ranking method currently utilized in the field. Application of this method is demonstrated on a large, coupled low-thrust trajectory problem. Mutual information also serves as the basis for an alternative global optimizer, called MIMIC, which is unrelated to Genetic Algorithms. Advancement to the current practice demonstrates the use of MIMIC as a global method that explicitly models problem structure with mutual information, providing an alternate method for globally searching multi-modal domains. By leveraging discovered problem inter-dependencies, MIMIC may be appropriate for highly coupled problems or those with large function evaluation cost. This work introduces a useful addition to the MIMIC algorithm that enables its use on continuous input variables. By leveraging automatic decision tree generation methods from Machine Learning and a set of randomly generated test problems, decision trees for which method to apply are also created, quantifying decomposition performance over a large region of the design space.

Constant-force mechanisms are mechanical devices that provide a near-constant output force over a prescribed deflection range. This thesis develops various optimization-based methods for designing robust constant-force mechanisms. The configuration of the mechanisms that are the focus of this research comprises a cam and a compliant spring fixed at one end while making contact with the cam at the other end. This configuration has proven to be an innovative solution in several applications because of its simplicity in manufacturing and operation. In this work, several methods are introduced to design these mechanisms, and reduce the sensitivity of these mechanisms to manufacturing uncertainties and frictional effects. The mechanism's sensitivity to these factors is critical in small scale applications where manufacturing variations can be large relative to overall dimensions, and frictional forces can be large relative to the output force. The methods in this work are demonstrated on a small scale electrical contact on the order of millimeters in size. The method identifies a design whose output force is 98.20% constant over its operational deflection range. When this design is analyzed using a Monte Carlo simulation the standard deviation in constant force performance is 0.76%. When compared to a benchmark design from earlier research, this represents a 34% increase in constant-force performance, and a reduction from 1.68% in the standard deviation of performance. When this new optimal design is evaluated to reduce frictional effects a design is identifed that shows a 36% reduction in frictional energy loss while giving up, however, 18.63% in constant force.

<p>In this thesis, the problem of controlling a surgical masterand slave system with force reflection is studied. The problemof stiff contacts between the slave and the environment isgiven specific attention. The work has been carried out at KTHbased on an initial cooperation with Karolinska Sjukhuset. Theaim of the over all project is to study the possibilities forintroduction of a force reflective teleoperator in neurologicalskullbase operations for the particular task of bone millingand thereby, hopefully, increase patient safety, decreasesurgeon workload and cost forthe society.</p><p>The main contributions of this thesis are:</p><p>Derivation of a dynamical model of the master andoperator’s finger system and, experimental identificationof ranges on model parameter values. Based on this model, theinteraction channel controllers optimized for transparency arederived and modified to avoid the influence of the uncertainmodel parameters. This results in a three channel structure. Todecrease the influence of the uncertain parameters locally atthe master, a control loop is designed such that the frequencyresponse of the reflected force is relatively unaffected by theuncertainties, a result also confirmed in a transparencyanalysis based on the H-matrix. The developed teleoperatorcontrol structure is tested in experiments where the operatorcould alter the contact force without facing any problems aslong as the slave is in contact with the environment.</p><p>As a result of the severe difficulties for the teleoperatorto move from free space motion to in-contact manipulationwithout oscillative behaviour, a new detection algorithm basedon passivity theory is developed. The algorithm is able todetect the non-passive behaviour of the actual teleoperatorinduced by the discrete change in system dynamics occurring atthe contact instant. A stabilization controller to be activatedby the detection algorithm is designed and implemented on themaster side of the teleoperator. The detection algorithm andthe stabilization controller are shown highly effective in realexperiments.</p><p>All major research results presented in the thesis have beenverified experimentally.</p><p><b>Keywords</b>Teleoperator, Force Feedback, Passivity, StiffContacts, Control, Robustness, Transparency, Bone Milling,Uncertainty</p>

Detection and control of humidity is very important in our everyday life.Humidity sensors are used in many areas, such as meteorology,environmental protection, medicine, food industry, agriculture, etc.Various transduction techniques, such as capacitive, resistive, acoustic,optical and mechanical, have been adopted for the design of humiditysensors.In the last two decades, carbon nanomaterials materials,especially graphene, are taking their place in the production of humiditysensors. In addition to graphene, graphene oxide (Graphene-oxide-GO)is involved in many areas from electronics to sensors. Printed electronicsincreasingly becomes the leading technology in the fabrication ofsensors. In addition to inexpensive manufacturing and additive processeswith reduced infrastructure, the benefits of printed technology are lowpowercomponents, flexible, transparent, thin, components that can beembedded in/on clothes, as well as the production of a large number ofcomponents. In the last few years, robots are more involved in human&rsquo;slife, which has led to the need for advanced research in the field ofrobotics. People communicate with the environment using four senses:touch, hearing, sight and taste. The sense of touch allows people to grabvarious objects, lift them, perform various tasks, etc. For this reason, it isvery important to develop touch sensors, that is, the sensors that will beincorporated into robotic fingers. As one type of such sensor, ForceSensing Resistors (FSR) are used. In these sensors, there is a change inresistance if the sensor is affected by a certain force.<br>Детекција и контрола влажности су од суштинског значаја у нашемсвакодневном животу. Сензори влаге се користе у многим областима,као што су метеорологија, заштита животне средине, медицина,прехрамбена индустрија, пољопривреда, итд. За дизајн сензора влагеуглавном се користе капацитивне, резистивне, акустичне, механичкеили оптичке структуре. У посљедње двије деценије све више се користенаноструктурни угљенични материјали, посебно графен. Поред графенавелику пажњу у многим областима од електронике до сензора јепривукао графен-оксид (Graphene-oxide - GO). Штампана електроникасве више постаје водећа технологија у изради сензора. Поред јефтинеизраде и адитивних процеса са смањеном инфраструктуром, предностиштампане технологије су компоненте мале масе, савитљиве,транспарентне, танке, компоненте које се могу уградити у/на гардеробуи носити, као и производња великог броја компоненти. У последњихнеколико година роботи се све више укључују у људски живот, што једовело до потребе за усавршавањем у области роботике. Људи саокружењем комуницирају помоћу четири чула: додира, слуха, вида иукуса. Чуло додира људима омогућава да дохвате различите предмете,подигну их, обављају различите задатке, итд. Из тог разлога је развојсензора додира, односно сензора који би се уградили у роботске прсте,од веома великог значаја. Као једна врста таквих сензора су отпорничкисензори силе (Force Sensing Resistors - FSR). Код ових сензора долазидо промјене отпорности уколико се на сенсор дјелује одређеном силом.<br>Detekcija i kontrola vlažnosti su od suštinskog značaja u našemsvakodnevnom životu. Senzori vlage se koriste u mnogim oblastima,kao što su meteorologija, zaštita životne sredine, medicina,prehrambena industrija, poljoprivreda, itd. Za dizajn senzora vlageuglavnom se koriste kapacitivne, rezistivne, akustične, mehaničkeili optičke strukture. U posljednje dvije decenije sve više se koristenanostrukturni ugljenični materijali, posebno grafen. Pored grafenaveliku pažnju u mnogim oblastima od elektronike do senzora jeprivukao grafen-oksid (Graphene-oxide - GO). Štampana elektronikasve više postaje vodeća tehnologija u izradi senzora. Pored jeftineizrade i aditivnih procesa sa smanjenom infrastrukturom, prednostištampane tehnologije su komponente male mase, savitljive,transparentne, tanke, komponente koje se mogu ugraditi u/na garderobui nositi, kao i proizvodnja velikog broja komponenti. U poslednjihnekoliko godina roboti se sve više uključuju u ljudski život, što jedovelo do potrebe za usavršavanjem u oblasti robotike. LJudi saokruženjem komuniciraju pomoću četiri čula: dodira, sluha, vida iukusa. Čulo dodira ljudima omogućava da dohvate različite predmete,podignu ih, obavljaju različite zadatke, itd. Iz tog razloga je razvojsenzora dodira, odnosno senzora koji bi se ugradili u robotske prste,od veoma velikog značaja. Kao jedna vrsta takvih senzora su otporničkisenzori sile (Force Sensing Resistors - FSR). Kod ovih senzora dolazido promjene otpornosti ukoliko se na sensor djeluje određenom silom.

Esta dissertação apresenta MagnetViz, uma técnica para visualização de grafos. Enquanto a maior parte das técnicas visualizam um layout de grafo estático pre-computado, MagnetViz permite que usuários dinamicamente alterem o layout de um grafo de forma a melhor satisfazer suas necessidades. Isso é feito ao construir em cima da metáfora de física de algoritmos dirigidos à força para proporcionar aos usuários imãs virtuais, que podem atrair nodos que satisfazem um conjunto de critérios associados a eles. Critérios podem ser baseados na topologia ou semântica do grafo. Através de boundary shapes, que são simples formas geométricas que podem ser colocadas ao redor de imãs, usuários podem também definir regiões na cena onde os nodos atraídos devem permanecer. Grafos são descritos usando GraphML, uma linguagem baseada em XML, que permite a especificação dos nodos e arestas e de atributos para essas entidades. Após a submissão de um grafo como entrada, MagnetViz o exibe utilizando uma versão modificada do algoritmo clássico de Fruchterman and Rheingold, e permite que usuário, a seguir, insira imãs na cena. Usuários podem construir as condições associadas aos imãs utilizando os atributos dos nodos e arestas, além de atributos topológicos próprios de grafos. Para a avaliação de MagnetViz, foi primeiro analisado o desempenho da técnica ao ajudar usuários a executarem tarefas definidas por uma taxonomia de tarefas de visualização de grafos encontrada na literatura. Então, MagnetViz foi testada em um contexto prático através de um estudo de caso. Uma rede de co-autorias foi escolhida como conjunto de dados e o protótipo de MagnetViz foi inicialmente usado para responder questões relevantes a esses dados e então testado por um grupo de potenciais usuários, que tinham de usa-lo para responder essas mesmas perguntas. Após testar a aplicação, os sujeiotos receberam questionários sobre usas opiniões quanto a usabilidade, aplicabilidade, relevância e resultados visuais da técnica. Enquanto alguns aspectos da técnica ainda podem ser melhorados, os resultados da avaliação provaram que MagnetViz é uma abordagem válida para interação com visualizações de grafos.<br>This dissertation presents MagnetViz, a technique for the visualization of graphs. While most techniques visualize a static pre-computed graph layout, MagnetViz allows users to dynamically alter the layout of a graph to better satisfy their needs. This is done by building on the physics metaphor of force-directed algorithms to provide users with virtual magnets, which can attract nodes that fulfill a set of criteria associated with them. Criteria can be based on either the topology or semantics of the graph. Through boundary shapes, which are simple geometric shapes that can be placed around magnets, users can also define regions within the scene where the attracted nodes should remain. Graphs are described in GraphML, a XML-like description language which allows the specification of nodes and edges between nodes as well as attributes associated to nodes and edges. After loading a graph, Magnetviz displays it using a slightly modified version of the classical Fruchterman and Reingold' algorithm, and allows the user to insert magnets. Users can build the criteria associated with the magnets using the attributes of nodes and/or edges, besides the common graphs' topological attributes. For MagnetViz's evaluation, it was first analyzed how the technique fared in aiding users to perform tasks defined by a graph visualization task taxonomy described in the literature. Then, MagnetViz was tested within a practical context by means of a case study. A co-authorship network was chosen as the target dataset. The MagnetViz prototype was initially used to answer questions relevant to this dataset and then tested by a group of potential users, who had to use it to answer these same questions. After trying the application, subjects answered questionnaires about their opinion on the technique's usability, applicability, relevance and visual results. While some aspects of the technique should still be refined, results of the evaluation proved MagnetViz to be a valid approach when it comes to interaction with graph visualizations.

Faire directement usage de nos mains pour explorer des environnements virtuels et interagir avec leur contenu permet une interaction à la fois naturelle et convaincante. Dans ce manuscrit de thèse, nous visons à améliorer l’interaction avec les mains dans le contexte de la Réalité Virtuelle en abordant deux défis majeurs : (1) faciliter le contrôle de modèles de mains articulées et (2) fournir des sensations haptiques au travers d’interfaces accessibles. Nous abordons tout d’abord l’interaction au travers de mains virtuelles articulées et proposons deux méthodes pour faciliter leur contrôle. Premièrement, nous réduisons leurs nombreux degrés de liberté de façon à pouvoir exploiter des interfaces tactiles courantes. Le système qui en résulte permet aux utilisateurs de contrôler une main virtuelle en réalisant des gestes sur la surface de la tablette. Ensuite, nous adoptons une autre approche et séparons les degrés de liberté des mains virtuelles entre deux interfaces haptiques contrôlées en parallèle. Par cette distribution des contrôles et des retours de force, les utilisateurs sont exposés à des effets haptiques variés, autrement réservés à des interfaces haptiques coûteuses. Nous abordons ensuite le sujet du retour haptique pour différents types d’interaction avec les mains. Pour cela, nous combinons des retours passifs à des retours pseudo-haptiques en tant qu’alternative à l’usage d’interfaces actives complexes et encombrantes. Dans un premier temps, nous considérons l’interaction avec les bras et proposons une armature élastique attachés à l’utilisateur qui fournit un retour de force égocentrique tout en conservant sa mobilité. Nous abordons ensuite le sujet de la saisie d’objets virtuels et proposons un nouveau paradigme d’interaction basé sur une interface élastique qui reproduit les mouvements de préhension et fournit un retour adapté et modulable par un effet pseudo-haptique. Finalement, nous considérons la manipulation fine avec les doigts et proposons un exosquelette passif qui les contraint séparément, associé à un retour pseudo-haptique multi-doigt simulant l’interaction avec des matériaux hétérogènes<br>Directly using our hands to explore virtual environments and interact with their contents produces a natural and compelling interaction. In this thesis, we propose contributions to improve hand-based interaction in the context of Virtual Reality by considering two main challenges: (1) improving the control of articulated hand models, and (2) providing haptic sensations with accessible techniques. We first address the challenge of interacting through realistic, articulated virtual hands and propose two methods for easing their control. As a first step, we reduce the degrees of freedom of complex hand models in order to make multi-finger interaction possible with common multi-touch interfaces. The resulting system allows users to control a virtual hand by performing gestures over a tactile tablet. Then, we take another approach and separate the degrees of freedom of one virtual hand between two haptic interfaces handled in parallel. Through this distribution of controls and feedback, users are exposed to a variety of haptic effects, otherwise restricted to complex haptic workstations. We then address the challenge of providing haptic sensations during hand-based interaction. To do so, we introduce different techniques that combine passive haptic feedback and pseudo-haptics as an alternative to complex and cumbersome active interfaces. We consider various types of interaction at different scales, starting with coarse interaction with the arm through an elastic armature that provides an egocentric and mobile haptic feedback. We then focus on object grasping and manipulation and propose an interaction paradigm that relies on elastic input devices for reproducing grasping gestures and perceiving modulable haptic properties through crossmodal feedback. Finally, we consider fine multi-finger manipulation and we propose a passive exoskeleton that constrains the digits individually, associated to a multi-finger pseudo-haptic feedback for simulating complex interaction with heterogeneous materials

La plupart de sondes oscillantes pour microscope à force atomique (AFM) commerciale sont basées sur des micro- cantilevers qui peuvent donner la mesure avec une résolution pico-Newton. Toutefois, ces résonateurs de flexion souffrent de faible fréquence de résonance et de facteur de qualité lors de l'utilisation dans un liquide. En outre, la détection optique limite également l'intégration du système et la miniaturisation de la sonde. Par conséquent, l’objectif principal des travaux présentés dans cette thèse est de remplacer le cantilever standard de l’AFM par un microsystème résonant à haute fréquence, présentant un facteur de qualité élevé et dont l’actionnement comme la détection seront intégrés. Plusieurs structures oscillantes sont proposées comme les anneaux vibrant en mode elliptique, les plaques rectangulaires vibrant en mode extension et les «dog-bone » résonateurs vibrant en mode extension. Les méthodes d’excitation et de détection intégrés sont étudiées et comparées, par exemple: excitation électrostatique/détection piézo-résistif, excitation/détection piézo-électrique et excitation thermique/détection piezo-résistif. Le procédé de fabrication de ces nouvelles sondes AFM sont définies et effectuées et les caractéristiques électriques et mécaniques sont mesurées telles que la fréquence de résonance, le facteur de qualité et l'amplitude des vibrations. En général, ces sondes résonnent entre 1 et 5 MHz avec un facteur de qualité de plusieurs milliers dans l'air. Plusieurs sondes sont ensuite monté sur un microscope AFM commercial et une imagerie sur les échantillons PMMA sont obtenus. La résolution de force la plus élevée déduite est d'environ 10 pN/Hz0.5<br>Most of commercial Atomic Force Microscope (AFM) oscillating probes are based on micrometric cantilevers which can make measurement with pico-Newton force resolution. However, these flexural vibrating cantilever resonators suffer from low quality factor when operating in liquids and the laser-based vibration sensing unit limits the integration and miniaturization. The major objective of this thesis is thus studying alternative MEMS-based AFM probe with high resonance frequency and quality factor as well as integrated driving and sensing transduction. Several in-plane oscillating structure is proposed such as flexural vibration ring resonators, extensional vibration rectangular plates and extensional vibration dog-bone resonators. Variety kinds of integrated driving and sensing methods are investigated and compared, for example: electrostatic excitation/piezoresistive detection, piezoelectric excitation/detection, and thermal excitation/piezo-resistive detection. The fabrication process of these new AFM probes are defined and carried out and both the electrical and mechanical properties are measured such as the resonance frequency, the quality factor and the vibration amplitude. In general, these probes resonate between 1 to 5 MHz with a quality factor of several thousands in air. Well-performing probes are then mounted onto a commercial AFM microscope and topographic images of patterned sample surfaces are obtained. The highest force resolution deduced from the measurement is about 10 pN/Hz0.5

Patients suffering from brachial plexus injury or other spinal cord related injuries often lose their hand functionality. They need a device which can help them to perform day to day activities by restoring some form of functionality to their hands. A popular solution to this problem are robotic exoskeletons, mechanical devices that help in actuating the fingers of the patients, enabling them to grasp objects and perform other daily life activities. This thesis presents the design of a novel exoskeleton glove which is controlled by a neural network-based controller. The novel design of the glove consists of rigid double four-bar linkage mechanisms actuated through series elastic actuators (SEAs) by DC motors. It also contains a novel rotary series elastic actuator (RSEA) which uses a torsion spring to measure torque, passive abduction and adduction mechanisms, and an adjustable base. To make the exoskeleton glove grasp objects, it also needs to have a robust controller which can compute forces that needs to be applied through each finger to successfully grasp an object. The neural network is inspired from the way human hands can grasp a wide variety of objects with ease. Fingertip forces were recorded from a normal human grasping objects at different orientations. This data was used to train the neural network with a R2 value of 0.81. Once the grasp is initiated by the user, the neural network takes inputs like orientation, weight, and size of the object to estimate the force required in each of the five digits to grasp an object. These forces are then applied by the motors through the SEA and linkage mechanisms to successfully grasp an object autonomously.<br>Master of Science<br>Humans are one of the few species to have an opposable thumb which allows them to not only perform tasks which require power, but also tasks which require precision. However, unfortunately, thousands of people in the United States suffer from hand disabilities which hinder them in performing basic tasks. The RML glove v3 is a robotic exoskeleton glove which can help these patients in performing day to day activities like grasping semi-autonomously. The glove is lightweight and comfortable to use. The RML glove v3 uses a neural network based controller to predict the grasp force required to successfully grasp objects. After the user provides the required input, the glove estimates the object size and uses other inputs like object orientation and weight to estimate the grasp force in each finger linkage mechanism. The motors then drive the linkages till the required force is achieved on the fingertips and the grasp is completed.

The main topic of this research is modelling and design of high-speed, large-force and long life-time electromagnetic actuators based on Magnetic Shape Memory (MSM) alloys. These relatively new “smart” alloys that change shape in magnetic fields possess very promising properties such as large strain, considerable output stress and potentially very long fatigue life. However, there is still lack of a consistent design methodology for MSM-based devices which can be implemented using techniques common for engineering design. In order to bridge this gap, a modelling approach for MSM element in actuators is developed in which the complete magnetic circuit of MSM actuator is included into a single finite element (FE) model. This approach also allows accurate representation of MSM permeability change during the shape change capturing its effects on total reluctance of the magnetic circuit. Moreover, this approach allows studying the magnetic field distribution in the MSM element in single, two and multi-variant states in magnetic fields of varying strength. The modelling results show striking non-homogeneity of the magnetic field distribution, providing new insights on the magneto-mechanical behaviour of the MSM element. The modelling approach is verified through comparing the calculated MSM permeability change with previously reported results obtained by measurement. Using this modelling approach, electromagnetic analysis is conducted for eleven MSM actuators. The actuators are designed and optimised for a particular 0.1mm strain (displacement) and 10N force output for implementation in food-sorting machines. The conducted analysis also ensures robustness of the designs and stable multi-billion cycle operation. The very long lifetime is achieved through careful analysis of the magnetic circuit and the behaviour of the MSM element during operation. Finally, thermal analysis is conducted for the designed actuators in order to ensure their thermal stability. In order to overcome challenges associated with a very low operating temperature limit of the MSM element in actuators, different available cooling conditions are studied. Moreover, an energy-efficient operation cycle is developed that takes advantage of the shape memory effect of the MSM element also taking into account the pressure change in the pneumatic valve of a sorting machine. The analysis shows multiple regimes which allow thermal stability in a 300Hz pulsed excitation cycle. Implementation of the developed operating cycle also leads to the considerable increase in overall efficiency.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 151-163).<br>Our ability to purposefully move across varied terrain requires us to have knowledge of the interactions our feet have with the external environment. However, existing sensing methods are inadequate to address the many unique demands of legged locomotion (i.e. fragile structures, incapable of handling large impact forces and noise caused by inertial loads during stride). This research is a study of how best to replicate the role of skin mechanoreceptors that enable our biological counterparts to perform dynamic maneuvers, and to develop innovative sensors that would empower the next generation of agile robots and smart shoes. The thesis introduces new design principles and methodologies for developing multi-axis, large magnitude force sensors based on stress fields to achieve these goals. Fabrication methods are presented for a monolithic elastomeric footpad that is biologically inspired, allowing it to measure large magnitude forces in both normal and shear axes while being compact, lightweight, impact robust, dust tight, and waterproof. The key principle that enables this is termed Stress Field (SF) based force sensing. Instead of funneling the load path directly through a few sensors in traditional force sensing methods, SF based force sensing allows the sampling of the stress distribution over the entire footpad surface through an array of piezoresistive sensor elements. The force estimator is constructed in two steps. First, linear regression fits the sensor readings to normal and shear forces. Then, machine learning is used as a nonlinear function approximator on the residual to further refine the force estimator to achieve greater accuracy. To enable these SF force sensor to be reproduced or customized for different needs, guidelines are provided in the form of simple design principles based on biological receptive fields, as well as an analytical model for cylindrical sensor types. For more complex sensor geometries, a material model of the elastomer is experimentally characterized, and Finite Element Analysis (FEA) can be used to determine the optimal configurations of these sensor arrays for different sensing needs. To show the feasibility of these SF force sensors, they have been validated for both robotic and human locomotion. For robotic locomotion, a hemispherical design was developed and implemented on the MIT Cheetah, a quadrupedal running robot, as well as on Little HERMES, a bipedal robot. For human locomotion, two prototypes of force sensing shoes have been fabricated based on cylindrical SF force sensors as a proof of concept. In the future, these lightweight, low-cost, multi-axis force sensors can be customized for different applications and fully integrated into smart shoes, prosthetic devices, and robotic exoskeletons to provide the real-time ground reaction force data. This data would enable new capabilities in various fields such as healthcare, sports analytics, virtual reality, and robotics.<br>by Meng Yee (Michael) Chuah.<br>Ph. D.

This thesis presents a multi-physics-based approach to the design and analysis of smart cutting tools for emerging industrial requirements, within an innovative design process. The design process is in stages according to design specifications and requires analysis, conceptual design, detailed design, prototype production and service testing. The research presented in the thesis follows the design process but focuses on the detailed design of the smart turning tool, including mechanical design, electrical wiring and sensor circuitry, embedded algorithms development, and multi-physics-based simulation for the tool system integration, design analysis and optimisation. The thesis includes the introduction of the research background, a critical literature review of the research topic, a multi-physics-based design and analysis of the smart cutting tool, a mechanical structural detail design of the prototype smart turning tool, the electrical system design focusing on cutting force measurement and embedded wireless communication features, and the final experimental testing and calibration of the smart cutting tool. The contributions to knowledge are highlighted in the conclusions chapter towards the end of the thesis. The research proposes multi-physics-based design and analysis concepts for a smart turning tool, which can measure the cutting forces on a 0.1 N scale and can also be used to monitor the tool condition, particularly for ultraprecision and micro-machining purposes. The smart turning tool is a sensored tool, constructed with wireless and plug-and-produce features. The tool design modelling and simulation was undertaken within a multi-physics modelling and analysis environment-based on COMSOL. This integrates the piezoelectric physics with mechanical structural design and radio frequency electronic communications of cutting force signals. The multi-physics simulation method takes account of all design-mechanics-physics-electronics analysis and transformations simultaneously within one computational environment, including FEA analysis, modal analysis, structural deformation, lead piezoelectric effect and wireless data/signal simulation. With the multi-physics simulation developed, the integrated design of the smart turning tool and its performance can be physically analysed and optimised in a virtual environment. The tool design process follows the total design methodology, which can be strictly executed in several design stages. Both mechanical and electrical design of the smart cutting tool are embodied into the tool detail design. The tool mechanical structure is systematically built from the selection of the tool material, through the structure analysis and further progressed with static force – strain/stress transformation, equivalent force measurement and calibration. The electrical circuitry was systematically developed from developing the customised charge amplifier, detail design of the main circuitry and coding development procedure, preliminary PCB fabrication and multi-sensor port PCB development, as well as the real-time cutting force monitoring programming and interface coding. The experiment calibrations and cutting trials with the tool system are also designed in light of the total design methodology. The experiment procedure for using the smart turning tool is further presented in two different sections. The thesis concludes with a further discussion on the main research findings, which are further supported by the highlighted contributions to knowledge and recommendations for future work.

Beam-based Compliant Mechanisms (CMs) are increasingly studied and implemented in precision engineering due to their advantages over the classic rigid-body mechanisms, such as scalability and reduced need for maintenance. Straight beams with uniform cross section are the basic modules in several concepts, and can be analyzed with a large variety of techniques, such as Euler-Bernoulli beam theory, Pseudo-Rigid Body (PRB) method, chain algorithms (e.g.~the Chained Beam-Constraint Model, CBCM) and Finite Element Analysis (FEA). This variety is unquestionably reduced for problems involving special geometries, such as curved or spline beams, variable section beams, nontrivial shapes and, eventually, contacts between bodies. 3D FEA (solid elements) can provide excellent results but the solutions require high computational times. This work compares the characteristics of modern and computationally efficient modeling techniques (1D FEA, PRB method and CBCM), focusing on their applicability in nonstandard problems. In parallel, as an attempt to provide an easy-to-use environment for CM analysis and design, a multi-purpose tool comprising Matlab and modern Computer-Aided Design/Engineering (CAD/CAE) packages is presented. The framework can implement different solvers depending on the adopted behavioral models. Summary tables are reported to guide the designers in the selection of the most appropriate technique and software architecture. The second part of this work reports demonstrative case studies involving either complex shapes of the flexible members or contacts between the members. To improve the clarity, each example has been accurately defined so as to present a specific set of features, which leads in the choice of a technique rather than others. When available, theoretical models are provided for supporting the design studies, which are solved using optimization approaches. Software implementations are discussed throughout the thesis. Starting from previous works found in the literature, this research introduces novel concepts in the fields of constant force CMs and statically balanced CMs. Finally, it provides a first formulation for modeling mutual contacts with the CBCM. For validation purposes, the majority of the computed behaviors are compared with experimental data, obtained from purposely designed test rigs.

This thesis presents an investigation of braking system characteristics, brake system performance and brake system component design parameters that influence brake pedal force / displacement characteristics as ‘felt’ by the driver in a passenger car. It includes detailed studies of individual brake system component design parameters, operation, and the linear and nonlinear characteristics of internal components through experimental study and simulation modelling. The prediction of brake pedal ‘feel’ in brake system simulation has been achieved using the simulation modelling package AMESim. Each individual brake system component was modelled individually before combining them into the whole brake system in order to identify the parameters and the internal components characteristics that influence the brake pedal ‘feel’. The simulation predictions were validated by experimentally measured data and demonstrated the accuracy of simulation modelling. Axisymmetric Finite Element Analysis (using the ABAQUS software) was used to predict the behaviour of nonlinear elastomeric internal components such as the piston seal and the booster reaction disc which was then included in the AMESim simulation model. The seal model FEA highlighted the effects of master cylinder and caliper seal deformation on the brake pedal ‘feel’. The characteristics of the brake booster reaction disc were predicted by the FEA and AMESim simulation modelling and these results highlighted the importance of the nonlinear material characteristics, and their potential contribution to brake pedal ‘feel’ improvement. A full brake system simulation model was designed, prepared, and used to predict brake system performance and to design a system with better brake pedal ‘feel’. Each of the brake system component design parameters was validated to ensure that the braking system performance was accurately predicted. The critical parameter of brake booster air valve spring stiffness was identified to improve the brake ‘pedal ‘feel’. This research has contributed to the advancement of automotive engineering by providing a method for brake system engineers to design a braking system with improved pedal ‘feel’. The simulation model can be used in the future to provide an accurate prediction of brake system performance at the design stage thereby saving time and cost.

Cette thèse a pour but de développer le pendant in silico des étapes clés du Fragment-Based Drug Design (FBDD), et ce dans le cadre plus général du développement de l'outil S4MPLE. Le FBDD génère des ligands drug-like à partir de petites molécules (fragments). Après une étape de validation de S4MPLE et de sa fonction d'énergie, un recentrage autour du FBDD est réalisé, à travers le docking puis l'optimisation virtuelle de fragments par growing ou linking (G/L). Cette stratégie reposesur 1) la création d'une chimiothèque focalisée en connectant un ou deux fragment(s) avec des linkers pré-générés, et 2) l'échantillonnage avec S4MPLE des composés chimères dans le site avec des contraintes. Des simulations de G/L plus ou moins ambitieuses (site flexible, ajout de H2O libres) permettent de valider cette approche avec des études rétrospectives basées sur des données expérimentales. La dernière phase de la thèse a consisté à appliquer ce protocole in silico à un projet de l'entreprise.

Carefree handling refers to the ability of a pilot to operate an aircraft without the need to continuously monitor aircraft operating limits. At the heart of all carefree handling or maneuvering systems, also referred to as envelope protection systems, are algorithms and methods for predicting future limit violations. Recently, envelope protection methods that have gained more acceptance, translate limit proximity information to its equivalent in the control channel. Envelope protection algorithms either use very small prediction horizon or are static methods with no capability to adapt to changes in system configurations. Adaptive approaches maximizing prediction horizon such as dynamic trim, are only applicable to steady-state-response critical limit parameters. In this thesis, a new adaptive envelope protection method is developed that is applicable to steady-state and transient response critical limit parameters. The approach is based upon devising the most aggressive optimal control profile to the limit boundary and using it to compute control limits. Pilot-in-the-loop evaluations of the proposed approach are conducted at the Georgia Tech Carefree Maneuver lab for transient longitudinal hub moment limit protection. Carefree maneuvering is the dual of carefree handling in the realm of autonomous Uninhabited Aerial Vehicles (UAVs). Designing a flight control system to fully and effectively utilize the operational flight envelope is very difficult. With the increasing role and demands for extreme maneuverability there is a need for developing envelope protection methods for autonomous UAVs. In this thesis, a full-authority automatic envelope protection method is proposed for limit protection in UAVs. The approach uses adaptive estimate of limit parameter dynamics and finite-time horizon predictions to detect impending limit boundary violations. Limit violations are prevented by treating the limit boundary as an obstacle and by correcting nominal control/command inputs to track a limit parameter safe-response profile near the limit boundary. The method is evaluated using software-in-the-loop and flight evaluations on the Georgia Tech unmanned rotorcraft platform- GTMax. The thesis also develops and evaluates an extension for calculating control margins based on restricting limit parameter response aggressiveness near the limit boundary.

Several sensor technologies have been developed and experimented over the last few decades to cater various needs of medical diagnostics. Among these, fiber optic sensors, in particular, Fiber Bragg Grating (FBG) based sensors have attracted considerable attention due to their inherent advantages such electrical passiveness, immunity to Electro Magnetic Interference (EMI), chemical inertness, etc. The present research work focuses on design, development and validation of FBG sensor based devices for measurement of certain healthcare parameters in the context of foot function/gait cycle, cardiac and breathing activity, nostril dominance, hand grip/wrist angle force function, etc. The experimental work presented here emphasizes on the effectiveness and competitiveness of the FBG devices developed, in comparison with standard tools such as Accelerometer, Load cell, Electronic Stethoscope, Electromyogram and Dynamometer. In the field of human balance, stability and geriatrics, two independent FBG devices namely, Fiber Bragg Grating based Stability Assessment Device (FBGSAD) and Optical Sensor Ground Reaction Force measurement Platform (OSGRFP) have been designed, developed and experimented for postural stability assessment and gait analysis respectively. The result of these studies have significant implications in understanding of the mechanism of plantar strain distribution, identifying issues in gait cycles, detecting foot function discrepancies, identifying individuals who are susceptible to falls and to qualify subjects for balance and stability. In the field of ergonomic assessment, Fiber Braggs Grating based Hand Grip Device (FBGHGD) is designed and developed for the measurement of hand grip force which helps in the understanding of several important biomechanical aspects such as neuromuscular system function, overall upper-limb strength, vertebral fracture, skeletal muscle function, prediction of disability, incapacity, mortality and bone mass density (forearm, skeletal sites, spine, hip etc.). Further as an extension of this work, the FBGHGD is used for measurement of force generated by the wrist in different positions of the flexion and extension which relates to the wrist muscle activity and its enactment. In the field of cardiac activity monitoring, a novel, in-vivo, non-invasive and portable device named Fiber Bragg Grating based Heart Beat Device (FBGHBD) is developed for the simultaneous measurement of respiratory and cardiac activities. The work involves designing FBGHBD, validating its performance against traditional diagnostic systems like electronic stethoscope, exploration of its clinical relevance and the usage of FBGHBD in studies involving normal persons and patients with myocardial infarction. The unique design of FBGHBD provides critical information such as nascent morphology of cardiac and breathing activity, heart rate variability, heart beat rhythm, etc., which can assist in early clinical diagnosis of many conditions associated to heart and lung malfunctioning. Further, the scope of this work extends towards evaluating several signal processing algorithms and demonstrating a suitable signal processing architecture for real-time extraction of heart beat and respiratory rates along with its nascent morphologies for critical health care application. In the area of breath monitoring, a Nostril Pressure and Temperature Device (NPTD) is designed and developed which aims at simultaneous, accurate and real-time measurement of nostril air flow pressure and temperature to aid in clinical diagnosis of nasal dysfunction and associated nose disorders. The results of NPTD can offer certain vital features like breathing pattern, respiratory rate, changes in individual nostril temperature/pressure, nostrils dominance, body core temperature etc., which can assist in early clinical diagnosis of breathing problems associated with heart, brain and lung malfunctioning. Since the research work in this thesis involve experiments engaging human subjects, necessary approvals from the ethical committee is obtained before the experiments and required ethical procedures are followed during all the experimental trials.

Several sensor technologies have been developed and experimented over the last few decades to cater various needs of medical diagnostics. Among these, fiber optic sensors, in particular, Fiber Bragg Grating (FBG) based sensors have attracted considerable attention due to their inherent advantages such electrical passiveness, immunity to Electro Magnetic Interference (EMI), chemical inertness, etc. The present research work focuses on design, development and validation of FBG sensor based devices for measurement of certain healthcare parameters in the context of foot function/gait cycle, cardiac and breathing activity, nostril dominance, hand grip/wrist angle force function, etc. The experimental work presented here emphasizes on the effectiveness and competitiveness of the FBG devices developed, in comparison with standard tools such as Accelerometer, Load cell, Electronic Stethoscope, Electromyogram and Dynamometer. In the field of human balance, stability and geriatrics, two independent FBG devices namely, Fiber Bragg Grating based Stability Assessment Device (FBGSAD) and Optical Sensor Ground Reaction Force measurement Platform (OSGRFP) have been designed, developed and experimented for postural stability assessment and gait analysis respectively. The result of these studies have significant implications in understanding of the mechanism of plantar strain distribution, identifying issues in gait cycles, detecting foot function discrepancies, identifying individuals who are susceptible to falls and to qualify subjects for balance and stability. In the field of ergonomic assessment, Fiber Braggs Grating based Hand Grip Device (FBGHGD) is designed and developed for the measurement of hand grip force which helps in the understanding of several important biomechanical aspects such as neuromuscular system function, overall upper-limb strength, vertebral fracture, skeletal muscle function, prediction of disability, incapacity, mortality and bone mass density (forearm, skeletal sites, spine, hip etc.). Further as an extension of this work, the FBGHGD is used for measurement of force generated by the wrist in different positions of the flexion and extension which relates to the wrist muscle activity and its enactment. In the field of cardiac activity monitoring, a novel, in-vivo, non-invasive and portable device named Fiber Bragg Grating based Heart Beat Device (FBGHBD) is developed for the simultaneous measurement of respiratory and cardiac activities. The work involves designing FBGHBD, validating its performance against traditional diagnostic systems like electronic stethoscope, exploration of its clinical relevance and the usage of FBGHBD in studies involving normal persons and patients with myocardial infarction. The unique design of FBGHBD provides critical information such as nascent morphology of cardiac and breathing activity, heart rate variability, heart beat rhythm, etc., which can assist in early clinical diagnosis of many conditions associated to heart and lung malfunctioning. Further, the scope of this work extends towards evaluating several signal processing algorithms and demonstrating a suitable signal processing architecture for real-time extraction of heart beat and respiratory rates along with its nascent morphologies for critical health care application. In the area of breath monitoring, a Nostril Pressure and Temperature Device (NPTD) is designed and developed which aims at simultaneous, accurate and real-time measurement of nostril air flow pressure and temperature to aid in clinical diagnosis of nasal dysfunction and associated nose disorders. The results of NPTD can offer certain vital features like breathing pattern, respiratory rate, changes in individual nostril temperature/pressure, nostrils dominance, body core temperature etc., which can assist in early clinical diagnosis of breathing problems associated with heart, brain and lung malfunctioning. Since the research work in this thesis involve experiments engaging human subjects, necessary approvals from the ethical committee is obtained before the experiments and required ethical procedures are followed during all the experimental trials.

Das seitliche Kraftwiderstandssystem, in diesem Fall Stahlbetonkernwände eines 10-stöckigen Gebäudes, das aus Schwerkraftstützen und Scherwänden besteht, wurde linear (unter der Annahme eines linearen elastischen Materialverhaltens von Beton) und nichtlinear gerissen (unter Berücksichtigung des Materialverhaltens von Beton) unter seismische Belastung analysiert. Erst wurde die grundlegenden Methode der äquivalenten Seitenkraft zur Schätzung der seismischen Belastungen benutzt, später wurde die aktuelle Methode The Performance Based Seismic Design verwendet, bei der reale seismische Aufzeichnungen verwendet werden und die Beschleunigungen mithilfe der Software ETABS auf das Gebäude angewendet werden. Nach dem Anwenden der Beschleunigungen wurden die maximal resultierenden Kräfte und Verformungen bewertet. Das Gebäude wurde dann für die maximal resultierenden Kräfte ausgelegt.Der Inhalt des Hauptberichts ist: - Allgemeine Beschreibung des Gebäudes, seismische Standortinformationen, Standortantwortspektren, Belastung und seismische Kräfte einschließlich Analyse des modalen Antwortspektrums. - Lineares Design des Modells für Schwerkraft und seismische Belastungen, P-M-Wechselwirkungsdiagramme für den U-Querschnitt aus Stahlbeton, Entwurf einer Längs- und Schubbewehrung der Scherwände und des Koppelbalkens. - Zwei Varianten des nichtlinearen Modells, bei denen die Kernwand (Scherwände) gemäß jeder Variante entworfen wird, wobei der Einfluss des Dämpfungsmodells auf das nichtlineare dynamische Verhalten sowie der Einfluss des Kopplungsstrahlmodells auf das nichtlineare dynamische Verhalten untersucht werden. - Entwurfsüberprüfung, erst mit der Definition der Leistungsobjekte und Modell für die Zeitverlaufsanalyse. Es wurden zwei Leistungsziele untersucht: Vollbetriebs- und Lebenssicherheitsprüfungen. - In zwei Fällen wurde eine zusätzliche Studie zur Reaktion von nicht strukturellen Elementen aufgrund seismischer Belastung durchgeführt: Überprüfung des Vollbetriebs und der Lebenssicherheit. - Die Durchsetzungszeichnungen wurden fertiggestellt und dem Bericht beigefügt. Schlussfolgerung und Empfehlungen waren am Ende des Berichts. Dies ist wichtig für die Gesellschaft, da die verwendete Methode für die seismische Planung jedes Gebäudes verwendet werden kann. Es könnte ein Holzbau oder ein Mauerwerk sein. Die Gestaltung eines Mauerwerksgehäuses wird Gegenstand eines zukünftigen Forschungsprojekts sein. Allgemeine Ziele: Lineare und nichtlineare seismische Bemessung von Stahlbetongebäuden unter Verwendung der 'seismischen Bemessung der Leistungsgrundlagen:Acknowledgement 4 PART I: General Information, Site and Loading 5 1. General Information About the Building 5 1.1. Specified Material Properties: 6 1.2. Site Information: 6 1.3. Geometry (Figure I.1): 7 2. Site Seismicity and Design Coefficients 7 2.1. USGS Results 7 2.2. Site Response Spectra 8 2.3. Design Coefficients And Factors For Seismic Force-Resisting Systems 8 3. Loading 9 3.1. Determination Of Seismic Forces 9 3.2. Modal Response Spectrum Analysis 9 3.3. Seismic Load Effects And Combinations 11 PART II: Core Wall Design - Linear Model 12 4. Model of ETABS 12 4.1. Geometry 12 4.2. Gravity Loads 13 4.3. Seismic Loads 15 4.4. Tabulated Selected Results From ETABS Analysis 16 5. P-M Interaction Diagrams 17 5.1. N-S Direction 17 5.2. E-W Direction 19 6. Lateral Force Resisting System, Linear 20 6.1. Longitudinal Reinforcement 20 6.2. Shear Reinforcement 22 6.3. Boundary Elements 24 6.3.1. Transverse Reinforcement Of Boundary Elements 26 6.4. Coupling Beams 27 7. Detailing 30 PART III: Site Response Spectra and Input Ground Motions 31 8. Performance Levels 31 8.1. ASCE 7-16 Target Spectra 31 8.2. Site Response Spectra 34 8.2.1. Ground Motion Conditioning 34 8.2.2. Amplitude Scaling 37 8.2.3. Pseudo Acceleration and Displacement Response Spectra 38 PART IV: Non-Linear Model 40 9. Variant 1 of Non-Linear Model 40 9.1. Complete Core Wall Design for Combined Axial-Flexure 40 9.2. Modal Analysis 43 9.3. Influence of the Damping Model on the Nonlinear Dynamic Response 49 10. Variant 2 of Non-Linear Model 57 10.1. Influence of the Coupling Beam Model on the Nonlinear Dynamic Response 57 10.2. Estimated Roof Displacement 68 PART V: Design Verification 70 11. General 70 11.1. Performance Objectives 70 11.2. Model For Time-History Analyses 71 11.3. Performance Level Verification 71 11.4. Fully Operational Performance Level Verification 71 11.5. Life Safety Performance Level Verification 78 PART VI: Capacity Design of Force Controlled Elements and Regions and Design of Acceleration-Sensitive Nonstructural Elements 87 12. General 87 12.1. Design Verification 87 12.1.1. Full Occupancy Case 87 12.1.2. Life Safety Case 91 12.1.3. Observations on Plots 93 12.2. Acceleration response spectra at roof level 94 12.2.1. Observations on Plots 95 12.3. Core Wall 97 12.4. Design Detail Comparison 103 12.5. Detailed Drawing 103 12.6. Diaphragm 104 12.7. Fire Sprinkler System 117 12.8. Overhanging Projector 119 PART VII: Conclusion 122<br>Lateral Force Resisting System, in this case reinforced concrete core walls of a 10 story building consists of gravity columns and shear walls, has been analyzed in linear (assuming linear elastic material behavior of concrete) and nonlinear cracked (considering plastic material behavior of concrete) case, for seismic loading. Starting with the basic method of equivalent lateral force to estimate the seismic loads, then using the up to date method, The Performance Based Seismic Design, which uses real seismic records and apply the accelerations on the building using the software ETABS. After applying the accelerations, maximum resulted forces and deformations have been evaluated. The building then have been designed for the maximum resulted forces. The contents of the main report are: - General description of the building, site seismic information, site response spectra, loading and seismic forces including modal response spectrum analysis. - Linear design of the model for gravity and seismic loads, P-M interaction diagrams developed for U cross section from reinforced concrete, designing longitudinal and shear reinforcement of the shear walls and coupling beam. - Two variants of Nonlinear model, designing the core wall (shear walls) according to each variant, studying the influence of damping model on the nonlinear dynamic response, as well as the influence of the coupling beam model on the nonlinear dynamic response. - Design verification, starting with defining the performance objects, and model for time history analysis. Two performance objectives have been studied: Fully operational and Life safety level verifications. - Additional study was performed for the response of non-structural elements due to seismic loading in two cases: Fully operational and Life safety level verifications. - Reinforcement Drawings have been finalized and attached to the report. - Conclusion and recommendations was at the end of the report. It is important for the society, because the used method could be used for the seismic design of any building. It could be wood building or masonry building. Designing a masonry building case will be the subject of future research project. Overall objectives: Linear and Nonlinear seismic design of reinforced concrete building using the performance bases seismic design.:Acknowledgement 4 PART I: General Information, Site and Loading 5 1. General Information About the Building 5 1.1. Specified Material Properties: 6 1.2. Site Information: 6 1.3. Geometry (Figure I.1): 7 2. Site Seismicity and Design Coefficients 7 2.1. USGS Results 7 2.2. Site Response Spectra 8 2.3. Design Coefficients And Factors For Seismic Force-Resisting Systems 8 3. Loading 9 3.1. Determination Of Seismic Forces 9 3.2. Modal Response Spectrum Analysis 9 3.3. Seismic Load Effects And Combinations 11 PART II: Core Wall Design - Linear Model 12 4. Model of ETABS 12 4.1. Geometry 12 4.2. Gravity Loads 13 4.3. Seismic Loads 15 4.4. Tabulated Selected Results From ETABS Analysis 16 5. P-M Interaction Diagrams 17 5.1. N-S Direction 17 5.2. E-W Direction 19 6. Lateral Force Resisting System, Linear 20 6.1. Longitudinal Reinforcement 20 6.2. Shear Reinforcement 22 6.3. Boundary Elements 24 6.3.1. Transverse Reinforcement Of Boundary Elements 26 6.4. Coupling Beams 27 7. Detailing 30 PART III: Site Response Spectra and Input Ground Motions 31 8. Performance Levels 31 8.1. ASCE 7-16 Target Spectra 31 8.2. Site Response Spectra 34 8.2.1. Ground Motion Conditioning 34 8.2.2. Amplitude Scaling 37 8.2.3. Pseudo Acceleration and Displacement Response Spectra 38 PART IV: Non-Linear Model 40 9. Variant 1 of Non-Linear Model 40 9.1. Complete Core Wall Design for Combined Axial-Flexure 40 9.2. Modal Analysis 43 9.3. Influence of the Damping Model on the Nonlinear Dynamic Response 49 10. Variant 2 of Non-Linear Model 57 10.1. Influence of the Coupling Beam Model on the Nonlinear Dynamic Response 57 10.2. Estimated Roof Displacement 68 PART V: Design Verification 70 11. General 70 11.1. Performance Objectives 70 11.2. Model For Time-History Analyses 71 11.3. Performance Level Verification 71 11.4. Fully Operational Performance Level Verification 71 11.5. Life Safety Performance Level Verification 78 PART VI: Capacity Design of Force Controlled Elements and Regions and Design of Acceleration-Sensitive Nonstructural Elements 87 12. General 87 12.1. Design Verification 87 12.1.1. Full Occupancy Case 87 12.1.2. Life Safety Case 91 12.1.3. Observations on Plots 93 12.2. Acceleration response spectra at roof level 94 12.2.1. Observations on Plots 95 12.3. Core Wall 97 12.4. Design Detail Comparison 103 12.5. Detailed Drawing 103 12.6. Diaphragm 104 12.7. Fire Sprinkler System 117 12.8. Overhanging Projector 119 PART VII: Conclusion 122

碩士<br>國立高雄應用科技大學<br>機械工程系<br>105<br>A wearable lower-limb exoskeleton with force-based interface is developed for augmenting the load-carrying capability of users. Each limb of the exoskeleton has six degrees of freedom, however only the two joints at hip and knee are equipped with actuators. In order to control the exoskeleton such that its motion is almost synchronous with the user, force measuring modules are designed to measure the interaction forces between the exoskeleton and the user at waist, ankles, and foot soles. One of the interaction forces at waist is used to generate the stoop motion, while the others are used to generate the motions of ankles with respective to the waist by using the impedance control strategy. The desired angles of hip joints and knee joints can then be determined from the numerical integration method and inverse kinematic method. Finally, the position control method is applied to drive the exoskeleton to achieve the desired posture and motion of the user. Preliminary experiments of the prototype show that the exoskeleton and the control method can successfully transfer its weight and load to the ground, and the user almost does not feel the existence of the load. Besides, the prototype is also verified to be very helpful for those activities such as squatting, stooping, walking, and climbing stairs.

碩士<br>國立彰化師範大學<br>電機工程學系<br>102<br>Abstract The rehabilitation demand, caused by aging population, sports injuries, apoplexy and accidents, is rapidly increasing in recent years. Based on the principle of controlling circuit to provide a variable resistance, the study develops a rehabilitation system for hands, arms, feeds and legs by integrating microcomputer processor with designed mechanics. The consumer group and environmental factors are also investigated in the study to propose a customized system according to patients’ demand and statistic data. The rehabilitation system, including paddles, connecting sets, chairs, seatbacks, spring controllers etc, with the function of leg and hand rehabilitation, provides sufficient information of users’ exercising records for doctors and better practicability of rehabilitation system. The designed system contains seat cushion, armrests and provides enough space, adjustable power for safety consideration. Also, the rehabilitation information, recorded by microcomputer processor, appears on LED monitor for medical staff to understand users’ condition. With the designed mechanics, 44 percent of the system volume is reduced for easy storage by equiping paddles and roping stick into connecting sets. The experiment result shows that the paddling power can reach up to 6 kg while the rehabilitation system provides 12V, 0.9A, 10.8W power to the electromagnet. After discussing with doctors of orthopedics and neurosurgery, it is proved the proposed system is very suitable for patients with partial injuries or aging people with repeating rehabilitation. Keywords: Rehabilitation system, Microcomputer processor, Electromagnet.

碩士<br>國立中興大學<br>機械工程學系所<br>104<br>In practical uses, the parameters of robot manipulator and stiffness coefficient are not exactly known. Designing the controller is difficult when the robot manipulator with external disturbance and uncertainties. For machining applications, the force control strategy is needed to avoid the damage on working-space. Thus, we utilize the impedance force control to achieve design the proposed control approach. However, the traditional impedance force control is unavailable when the robot manipulator has uncertainties, and the researches of recent years are focused on static response rather than transient response in function approximation. Herein, we proposed the fuzzy neural system based adaptive impedance force controller design for robot manipulator to overcome this problem. Chapter 2, the fuzzy neural system (FNS) is adopted to estimate the dynamic model of robot manipulator and the stiffness coefficient of environment is estimated by gradient method to achieve the adaptive force control. The corresponding update laws of FNS and stability of close-loop system can be obtained by Lyapunov stability theorem. Chapter 3, we consider the system dynamic of robot manipulator and actuator to redesign the controller, and the corresponding update laws and stability analysis can be obtained based on Lyapunov stability theorem. In the robot control task space, the singularity problem may lead robot manipulator to loss control. Therefore, we propose a simple method to solve this problem. Finally, we employ our proposed control scheme on two-link robot manipulator and Mitsubishi RV2SDB 6 degree of freedom (DOF) robot manipulator to illustrate the performance and effectiveness.

碩士<br>國立高雄應用科技大學<br>模具工程系碩士班<br>102<br>This paper proposed a jig structure design optimization method based on the cutting froce prediction and the modal analysis of structure. The robustness and natural mode shape of jig were analyzed using different jig topology designs. Coefficients of cutting froce were found using cutting experiments. The natural mode shape, frequency, and mangnitute of the jig vibraiton were predicted using FEM simulation. Relationship of the cutting conditions and the structure vibration mode was established. Maximum deformations of jig under diferent cutting parameters were predicted and applied to improve the accuracy of cutting parts. The simulation results showed the proposed topology deisgns of jig were able to reduce deformation based on the suitable cutting condition selection.

碩士<br>國立高雄第一科技大學<br>電機工程研究所碩士班<br>103<br>Many pipes are used under the ground for transporting gas, liquid and protecting wire. These pipe systems usually become aging due to natural factors and so on. Furthermore, the pipe systems are prone to crack or corrosion, it will cause serious problem such as leakage, and pollution of field or underground water, even destroy the foundation or construction of buildings. Therefore, the　pipe systems need regular check to keep it to operate normally. We presented a pipe robot with flexible movements including forward, backward, rotation and helix motion. In special, the pipe robot is installed by inferred sensors and force sensors for adaptive size autonomously. The motion of above lets robot be able to estimate the forces on the inner surface of the pipes and pass obstacle easily. This robot is designed for moving into complex pipe systems such as horizontal pipe, vertical pipe, and curve pipe. Robot has a flexible mechanism design which autonomous fit to the pipes within a diameter range of 250-300 millimeters. Various aspects of the robot including its mechanical design, the control system as well as the adaptive diameter system will be discussed in detail. This thesis described a pipe inspection robot with multiple movements. The experiment result proved that this robot can move into horizontal and vertical pipe smoothly. In the future, we will set camera to detect obstacle and any kind of changing of different pipe.

博士<br>國立臺灣大學<br>機械工程學研究所<br>103<br>Recent years have seen increased attention being given to atomic force microscopy (AFM) in nano-scale measurement. In this dissertation, a holographic optical element (HOE) based AFM is designed and developed for operation in air and water. Unlike the bulk size and cumbersome procedures of laser beam deflection method, holographic pickup head has the advantages of easy control and simpler optical adjustment. The features of compact configuration, small size, and high sensitivity let HOE enhance the performance of AFM. Through theoretical analysis and software simulation, the translational S-curve between the light spot on photodiode and reflective plane displacement is deduced. According to the simulation results, the relevance of light spot shape, translational displacement, bending angle, and torsional angle are revealed. The detection functions of translational and angular displacements of the cantilever are demonstrated. The experiment of thermal noise spectrum verifies the stable performance and high sensitivity of holographic pickup head. The spring constant calibration of a micro cantilever is also derivative by thermal fluctuation method. AFM images of graphite display the single layer step (0.34 nm) in both air and water. The nanometer scale resolution by track error signal is also divided, thus verifying the resolution and stability of HOE-based AFM system. The images of non-contact optical profiler mode for microcircuit and tuberose epidermis tissue exemplify the feasibility and applicability of HOE-based profiler system in micron scale.

<p>This study is focused on designing and characterizing protein-based building blocks in order to construct self-assembled nano-structured biomaterials. In detail, this research aims to: (1) investigate a new class of proteins that possess nanospring behaviors at a single-molecule level, and utilize these proteins along with currently characterized elastomeric proteins as building blocks for nano-structured biomaterials; (2) develop a new method to accurately measure intermolecular interactions of self-assembling two or more arbitrary (poly)peptides, and select some of them which have appropriate tensile strength for crosslinking the proteins to construct elastomeric biomaterials; (3) construct well-defined protein building blocks which are composed of elastomeric proteins terminated with self-oligomerizing crosslinkers, and characterize self-assembled structures created by the building blocks to determine whether the elasticity of proteins at single-molecule level can be maintained.</p><p>Primary experimental methods of this research are (1) atomic force microscope (AFM) based single-molecule force spectroscopy (SMFS) that allows us to manipulate single molecules and to obtain their mechanical properties such as elasticity, unfolding and refolding properties, and force-induced conformational changes, (2) AFM imaging that permits us to identify topology of single molecules and supramolecular structures, and (3) protein engineering that allows us to genetically connect elastomeric proteins and self-assembling linkers together to construct well-defined protein building blocks.</p><p>Nanospring behavior of á-helical repeat proteins: We revealed that á-helical repeat proteins, composed of tightly packed á-helical repeats that form spiral-shaped protein structures, unfold and refold in near equilibrium, while they are stretched and relaxed during AFM based SMFS measurements. In addition to minimal energy dissipation by the equilibrium process, we also found that these proteins can yield high stretch ratios (>10 times) due to their packed initial forms. Therefore, we, for the first time, recognized a new class of polypeptides with nanospring behaviors. </p><p>Protein-based force probes for gauging molecular interactions: We developed protein-based force probes for simple, robust and general AFM assays to accurately measure intermolecular forces between self-oligomerization of two or more arbitrary polypeptides that potentially can serve as molecular crosslinkers. For demonstration, we genetically connected the force probe to the Strep-tag II and mixed it with its molecular self-assembling partner, the Strep-Tactin. Clearly characterized force fingerprints by the force probe allowed identification of molecular interactions of the single Strep-tag II and Strep-Tactin complex when the complex is stretched by AFM. We found a single energy barrier exists between Strep-tag II and Strep-Tactin in our given loading rates. Based upon our demonstration, the use of the force probe can be expanded to investigate the strength of interactions within many protein complexes composed of homo- and hetero-dimers, and even higher oligomeric forms. Obtained information can be used to choose potential self-assembling crosslinkers which can connect elastomeric proteins with appropriate strength in higher-order structures. </p><p>Self-assembled nano-structured biomaterials with well-defined protein-based building blocks: We constructed well-defined protein building blocks with tailored mechanical properties for self-assembled nano-structured materials. We engineered protein constructs composed of tandem repeats of either a I27-SNase dimer or a I27 domain alone and terminated them with a monomeric streptavidin which is known to form extremely stable tetramers naturally. By using molecular biology and AFM imaging techniques, we found that these protein building blocks transformed into stable tetrameric complexes. By using AFM based SMFS, we measured, to our knowledge for the first time, the mechanical strength of the streptavidin tetramer at a single-molecule level and captured its mechanical anisotropy. Using streptavidin tetramers as crosslinkers offers a unique opportunity to create well-defined protein based self-assembled materials that preserve the molecular properties of their building blocks.</p><br>Dissertation

碩士<br>逢甲大學<br>電機工程所<br>95<br>The main objective of this paper is to design and implement a force measurement device based on a personal computer for a cervical traction equipment. The force measurement device is based on a microcontroller. Firstly, the force signal is retrieved by a force sensor and convented into a digital signal. After the amplification and regulation. The measured digital signal and then feeds to the microcontroller for calculation and conversion. Then, the screen of the PC will show the results of force being measured on a patient. Finally, the prototype of force measurement device will be implemented and demonstrated.

碩士<br>國立清華大學<br>動力機械工程學系<br>96<br>This thesis presents a scanning mirror which is made of single crystal silicon structure with perfect reflective mirror plate, high quality factor, and high reliability. The driving force can be applied on the scanning mirror through the ferromagnetic material under the magnetic field. The design eliminates complicated coil routing and insulation layer deposition, and magnets. The rib structure on backside of mirror is designed to reduce the mass/stiffness ratio of the mirror plate. This study designs the “lever arm” structure and covered with ferromagnetic material to enhance the torque applied on the mirror. Beside, the magnetization of the ferromagnetic material is influenced by its planar geometry shape. Thus, this study also varying the geometric pattern of the ferromagnetic material covered on the “lever arm” to further increase the magneto-static force. The static measures of the scanning mirror include curvature and roughness of the mirror plate and thickness of ferromagnetic material. The dynamic measurement of the scanning mirror include frequency response, optical scanning angle versus driving power, affect by magnetization, and scanning pattern. The concept of magneto-static scanner is possible to apply to display refer to above measurements and testing.

碩士<br>義守大學<br>資訊工程學系碩士班<br>97<br>Reserve Force Five-day Muster-calls are carried out in Taiwan more than 10 times a year, each time 500 to 2000 people called. When the policy of picked troops is adopted and then the manpower is reduced, the current management system for Muster-call will suffer some training operation and equipment security problems. This paper uses radio frequency identification (RFID) and wireless network technologies to design a new management system for solving some of the problems. A prototype system has also been implemented. Our new management system has six distinct design chooses and corresponding improvements. First, in order to prevent substitute for another, the personal fingerprint is written into the RFID tag. Second, a RFID reader is placed along the barrack doorway for shortening the registration processing time. Third, a tag location system is implemented in the classroom for easy writing some location-aware or training-related programs. The fourth, gun parts are imbedded with several RFID tags. Those tags use the secret sharing ability to prevent gun parts from being stolen. The fifth, bullet head, bullet body and bullet tail all contain tags, some are heat resistant. Those tags can be used to detect the bullet abnormal usages. And the six, we write an I-phone interface program. The superior can use I-phone to do inquiry or updating operation remotely. Our prototype system has a registration processing, a gun parts security and a remote control subsystem. The Shamir secret sharing mechanism is implemented on a Cimtrac CU501R Reader and some low cost RFID tags. Visual Basic 2008 and Visual Web Developer 2008 are the main programming tools. The source codes are included at the end of this paper.

碩士<br>國立成功大學<br>電機工程學系<br>105<br>Impedance control is an important research topic in human-robot interaction be-cause it can increase the safety and the variety of interactions. The thesis realizes an impedance control system by mounting a 6-axis force sensor on the wrist of the home service robot. When the robot and a person are walking hand on hand, the robot detects the handing force from the person and generates a suitable pose of its end-effector and a moving path of its mobile platform to accomplish the leading and the guiding missions. The proposed impedance control system treats the end-effector of the robot arm as a point mass with physical property and detects the force from the environment to calcu-late the next pose which it should move to. Therefore, the arm can move following the force imposed by the person. For further improving the performance, we add a fuzzy controller to real-time adjust three parameters of the impedance control system and to plan the moving direction and velocity of the robot. In this thesis, we implement the impendence control system in leading and guiding missions. In the leading mission, the person leads the robot to go through a specific path. Whereas, the robot can guide a blind person by handing on her/his hand in the guiding mission. All the real experiments demonstrate the efficiency of the proposed system and the robot successfully accom-plishes these two missions.

Keratinocyte traction forces play a crucial role in wound healing. The aim of this study was to develop a novel cell traction force (CTF) transducer system based on cholesteryl ester liquid crystals (LC). Keratinocytes cultured on LC induced linear and isolated deformation lines in the LC surface. As suggested by the fluorescence staining, the deformation lines appeared to correlate with the forces generated by the contraction of circumferential actin filaments which were transmitted to the LC surface via the focal adhesions. Due to the linear viscoelastic behavior of the LC, Hooke's equation was used to quantify the CTFs by associating Young's modulus of LC to the cell induced stresses and biaxial strain in forming the LC deformation. Young's modulus of the LC was profiled by using spherical indentation and determined at approximately 87.1+/-17.2kPa. A new technique involving cytochalasin-B treatment was used to disrupt the intracellular force generating actin fibers, and consequently the biaxial strain in the LC induced by the cells was determined. Due to the improved sensitivity and spatial resolution ( approximately 1mum) of the LC based CTF transducer, a wide range of CTFs was determined (10-120nN). These were found to be linearly proportional to the length of the deformations. The linear relationship of CTF-deformations was then applied in a bespoke CTF mapping software to estimate CTFs and to map CTF fields. The generated CTF map highlighted distinct distributions and different magnitude of CTFs were revealed for polarized and non-polarized keratinocytes.

碩士<br>國立臺灣科技大學<br>電機工程系<br>94<br>Abstract A DC brushless motor has the characteristics of high torque and high power density. With proper electronic commutation, it can achieve comparable performance of a dc motor and has become a dominant drive in servo application. Common application of dc brushless motor uses hall sensors and the associated logic circuits to drive the motor. This thesis proposes a method of sensorless control which can achieve comparable driving performance without using hall sensors and, thus, increases economic benefit. Aiming at dc brushless motor control, this thesis uses the Mircochip dsPIC30F4012 as the control kernel, and combines peripheral circuits to develop a DC brushless motor control structure with current, velocity and position close-loops by using rotor position sensors. Apply to DC brushless motor sensorless control, this thesis using Y-connection resistances to obtain back electromagentic force. Utilizing low-passed filter to get its fundamental harmonic and estimate commutation sequence, and then developing a DC brushless motor sensorless drive method without current sensor and AD converter of controller . At last, using rotor velocity calculation to achieve velocity close-loop control . Analyzing results to verify the purpose of the sensorless control method in this thesis.

This study concerns the identification of the particular competences required by education, training and development practitioners (ETD practitioners) in the South African National Defence Force to develop suitable and appropriate career and training strategies. An applied research approach and a primarily quantitative approach were used. Questionnaires were completed by the commanding officers or the training managers, as well as the ETD practitioners at the education, training and development providers in the South African National Defence Force to determine the actual utilisation of ETD practitioners. Descriptive statistics were used to determine the roles, core competences, levels of competences and clusters of competences required by ETD practitioners in the South African National Defence Force. In addition, the actual utilisation of ETD practitioners was compared with a proposed competence profile that was based on the literature study in order to determine the competence gap that has to be addressed by means of career and training strategies.<br>Educational Studies<br>M.Ed.(Didactics)

Pervaporation (PV), a non-porous membrane separation process, is gaining considerable attention for solvent separation in a variety of industries ranging from chemical to food and pharmaceutical to petrochemicals. The most successful application has been the dehydration of organic liquids, for which hydrophilic membranes are used. However, during pervaporation, excessive affinity of water towards hydrophilic membranes leads to undesirable swelling (water absorption) of the membrane matrix. To control swelling, often hydrophilic membranes are crosslinked to modify physicochemical (surface and bulk) properties. Since the transport of species in pervaporation is governed by sorption (affected by surface and bulk properties) and diffusion (affected by bulk properties), it is essential to study the effect of crosslinking on the surface and bulk physicochemical properties and their effects on separation performance. This thesis focuses on the effect of crosslinking on the physicochemical properties (e.g., crystallinity, hydrophilicity, surface roughness) of hydrophilic polymeric membranes and their dehydration performance alcohol-water mixtures. Poly(vinyl alcohol), PVA was used as the base polymer to prepare membranes with various morphologies such as homogeneous, blended (with Chitosan, CS) and composite (with poly(sulfone), PSf) structures. Before applying the crosslinked membranes for the PV dehydration of alcohols, the physicochemical characterization were carried out using Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), tensile testing, contact angle and swelling experiments. The crosslinked membranes showed an increase in surface hydrophobicity from the contact angle measurements as compared to the uncrosslinked membranes. AFM surface topography showed that the membrane surfaces have nodular structures and are rough at the nanometer scale and affected by the crosslinking conditions such as concentration and reaction time. Surface hydrophobicity and roughness was found to increase with increasing degree of crosslinking. DSC measurements showed an increase in melting temperature of the polymer membranes after crosslinking. For the PV dehydration of ethanol, a decrease in flux and an increase in selectivity were observed with increase in the degree of crosslinking. Effects of membrane thickness (of PVA layer) for crosslinked PVA-PSf composite membranes were studied on PV dehydration of ethanol. Total flux and selectivity were statistically analyzed as a function of the membrane thickness. In general, the outcome agrees with the solution-diffusion (S-D) theory: the total flux was found to be significantly affected by the PVA layer thickness, while the selectivity remains nearly unaffected. Using the S-D theory, the mass transfer resistance of the selective layers was calculated and found to increase with thickness. The relatively small change observed for selectivity has been related to the crosslinking of the PVA layer that increases the surface hydrophobicity of the membrane. Chitosan-Poly(vinyl alcohol), or CS-PVA, blended membranes were prepared by varying the blending ratio to control membrane crystallinity and its effect on the PV dehydration of ethylene glycol. The blended membranes were crosslinked interfacially with trimesoyl chloride (TMC)/hexane. The crystallinity of the membrane was found to decrease with increasing CS wt% in the blend. Although the crosslinked CS-PVA blend membranes showed improved mechanical strength, they became less flexible as detected in tensile testing. The resulting crosslinked CS-PVA blended membranes showed high flux and selectivity simultaneously, for 70-80wt% CS in the blend. The effect of feed flow-rate was studied to find the presence of concentration polarization for 90wt% EG in feed mixture as well. The crosslinked blend membrane with 75wt% CS showed a highest total flux of 0.46 kg/m2/h and highest selectivity of 663 when operating at 70oC with 90wt% EG in the feed mixture. Effects of crosslinking concentration and reaction time of trimesoyl chloride (TMC) were studied on poly(vinyl alcohol)-poly(sulfone) or PVA-PSf composite membranes. Results showed a consistent trend of changes in the physicochemical properties: the degree of crosslinking, crystallinity, surface roughness, hydrophilicity and swelling degree all decrease with increasing crosslinking agent (TMC) concentration and reaction time. The crosslinked membrane performance was assessed with PV dehydration of ethylene glycol-water mixtures at a range of concentrations (30 to 90wt% EG). The total flux of permeation was found to decrease, while the selectivity to increase, with increasing TMC concentration and reaction time. The decrease in flux was most prominent at low EG concentrations in the feed mixtures. A central composite rotatable design (CCRD) of response surface methodology was used to analyze PV dehydration performance of crosslinked poly(vinyl alcohol) (PVA) membranes. Regression models were developed for the flux and selectivity as a function of operating conditions such as, temperature, feed alcohol concentration, and flow-rate. Dehydration experiments were performed on two different alcohol-water systems: isopropanol-water (IPA-water) and ethanol-water (Et-water) mixtures around the azeotrope concentrations. Judged by the lack-of-fit criterion, the analysis of variance (ANOVA) showed the regression model to be adequate. The predicted flux and selectivity from the regression models were presented in 3-D surface plots over the whole ranges of operating variables. For both alcohol-water systems, quadratic effect of temperature and feed alcohol concentration showed significant (p < 0.0001) influence on the flux and selectivity. A strong interaction effect of temperature and concentration was observed on the selectivity for the Et-water system. For the dehydration of azeotropic IPA-water mixture (87.5wt% IPA), the optimized dehydration variables were found to be 50.5oC and 93.7 L/hr for temperature and flow-rate, respectively. On the other hand for azeotropic Et-water mixture (95.5wt% Et), the optimized temperature and flow-rate were found to be 57oC and 89.2 L/hr, respectively. Compared with experiments performed at optimized temperature and feed flow-rate, the predicted flux and selectivity of the azeotropic mixtures showed errors to be within 3-6 %.

Miniature compliant grippers are designed and developed to manipulate biological cells and characterize them. Apart from grippers, other compliant mechanisms are also demonstrated to be effective in manipulation and characterization. Although scalability and force-sensing capability are inherent to a compliant mechanism, it is important to design a compliant mechanism for a given application. Two techniques based on Spring-lever models and kinetoelastostatic maps are developed and used for designing compliant devices. The kinetoelastostatic maps-based technique is a novel approach in designing a mechanism of a given topology and shape. It is also demonstrated that these techniques can be used to tune the stiffness of a mechanism for a given application. In situations where any single mechanism is incapable of executing a specific task, two or more mechanisms are combined into a single continuum with enhanced functionality. This has led to designs of composite compliant mechanisms. Biological cells are manipulated using compliant grippers in order to study their mechanical responses. Biological cells whose size varies from 1 mm (a large zebrafish embryo) to 10 µm (human liver cells), and which require the grippers to resolve forces ranging from 1 mN (zebrafish embryo) to 10 nN (human cells), are manipulated. In addition to biological cells, in some special cases such as tissue-cutting and cement-testing, inanimate specimens are used to highlight specific features of compliant mechanisms. Two extreme cases of manipulation are carried out to demonstrate the efficacy of the design techniques. They are: (i) breaking a stiff cement specimen of stiffness 250 kN/m (ii) gentle grasping of a soft zebrafish embryo of stiffness 10 N/m. Apart from manipulation, wherever it is viable, the mechanisms are interfaced with a haptic device such that the user’s experience of manipulation is enriched with force feedback. An auxiliary study on the characterization of cells is carried out using a micro¬pipette based aspiration technique. Using this technique, cells existing in different conditions such as perfusion, therapeutic medicines, etc., are mechanically characterized. This study is to qualitatively compare aspiration-based techniques with compliant gripper-based manipulation techniques. A compliant gripper-based manipulation technique is beneficial in estimating the bulk stiffness of the cells and can be extended to estimate the distribution of Young’s modulus in the interior. This estimation is carried out by solving an inverse problem. A previously reported scheme to solve over specified boundary conditions of an elastic object—in this case a cell—is improved, and the improved scheme is validated with the help of macro-scale specimens.

Miniature compliant grippers are designed and developed to manipulate biological cells and characterize them. Apart from grippers, other compliant mechanisms are also demonstrated to be effective in manipulation and characterization. Although scalability and force-sensing capability are inherent to a compliant mechanism, it is important to design a compliant mechanism for a given application. Two techniques based on Spring-lever models and kinetoelastostatic maps are developed and used for designing compliant devices. The kinetoelastostatic maps-based technique is a novel approach in designing a mechanism of a given topology and shape. It is also demonstrated that these techniques can be used to tune the stiffness of a mechanism for a given application. In situations where any single mechanism is incapable of executing a specific task, two or more mechanisms are combined into a single continuum with enhanced functionality. This has led to designs of composite compliant mechanisms. Biological cells are manipulated using compliant grippers in order to study their mechanical responses. Biological cells whose size varies from 1 mm (a large zebrafish embryo) to 10 µm (human liver cells), and which require the grippers to resolve forces ranging from 1 mN (zebrafish embryo) to 10 nN (human cells), are manipulated. In addition to biological cells, in some special cases such as tissue-cutting and cement-testing, inanimate specimens are used to highlight specific features of compliant mechanisms. Two extreme cases of manipulation are carried out to demonstrate the efficacy of the design techniques. They are: (i) breaking a stiff cement specimen of stiffness 250 kN/m (ii) gentle grasping of a soft zebrafish embryo of stiffness 10 N/m. Apart from manipulation, wherever it is viable, the mechanisms are interfaced with a haptic device such that the user’s experience of manipulation is enriched with force feedback. An auxiliary study on the characterization of cells is carried out using a micro¬pipette based aspiration technique. Using this technique, cells existing in different conditions such as perfusion, therapeutic medicines, etc., are mechanically characterized. This study is to qualitatively compare aspiration-based techniques with compliant gripper-based manipulation techniques. A compliant gripper-based manipulation technique is beneficial in estimating the bulk stiffness of the cells and can be extended to estimate the distribution of Young’s modulus in the interior. This estimation is carried out by solving an inverse problem. A previously reported scheme to solve over specified boundary conditions of an elastic object—in this case a cell—is improved, and the improved scheme is validated with the help of macro-scale specimens.

<div>Adsorbent technology is widely used in many industrial applications including waste heat recovery, water purification, and atmospheric revitalization in confined habitations. Astronauts depend on adsorbent-based systems to remove metabolic carbon dioxide (CO₂) from the cabin atmosphere; as NASA prepares for the journey to Mars, engineers are redesigning the adsorbent-based system for reduced weight and optimal efficiency. These efforts hinge upon the development of accurate, predictive models, as simulations are increasingly relied upon to save cost and time over the traditional design-build-test approach. Engineers rely on simplified models to reduce computational cost and enable parametric optimizations. Amongst these simplified models is the axially dispersed plug-flow model for predicting the adsorbate concentration during flow through an adsorbent bed. This model is ubiquitously used in designing fixed-bed adsorption systems. The current work aims to improve the accuracy of the axially dispersed plug-flow model because of its wide-spread use. This dissertation identifies the critical model inputs that drive the overall uncertainty in important output quantities then systematically improves the measurement and prediction of these input parameters. Limitations of the axially dispersed plug-flow model are also discussed, and recommendations made for identifying failure of the plug-flow assumption.</div><div><br></div><div>An uncertainty and sensitivity analysis of an axially disperse plug-flow model is first presented. Upper and lower uncertainty bounds for each of the model inputs are found by comparing empirical correlations against experimental data from the literature. Model uncertainty is then investigated by independently varying each model input between its individual upper and lower uncertainty bounds then observing the relative change in predicted effluent concentration and temperature (<i>e.g.</i>, breakthrough time, bed capacity, and effluent temperature). This analysis showed that the LDF mass transfer coefficient is the largest source of uncertainty. Furthermore, the uncertainty analysis reveals that ignoring the effect of wall-channeling on apparent axial dispersion can cause significant error in the predicted breakthrough times of small-diameter beds.</div><div><br></div><div>In addition to LDF mass transfer coefficient and axial-dispersion, equilibrium isotherms are known to be strong lever arms and a potentially dominant source of model error. As such, detailed analysis of the equilibrium adsorption isotherms for zeolite 13X was conducted to improve the fidelity of CO₂ and H₂O on equilibrium isotherms compared to extant data. These two adsorbent/adsorbate pairs are of great interest as NASA plans to use zeolite 13X in the next generation atmospheric revitalization system. Equilibrium isotherms describe a sorbent’s maximum capacity at a given temperature and adsorbate (<i>e.g.</i>, CO₂ or H₂O) partial pressure. New isotherm data from NASA Ames Research Center and NASA Marshall Space Flight Center for CO₂ and H₂O adsorption on zeolite 13X are presented. These measurements were carefully collected to eliminate sources of bias in previous data from the literature, where incomplete activation resulted in a reduced capacity. Several models are fit to the new equilibrium isotherm data and recommendations of the best model fit are made. The best-fit isotherm models from this analysis are used in all subsequent modeling efforts discussed in this dissertation.</div><div><br></div><div>The last two chapters examine the limitations of the axially disperse plug-flow model for predicting breakthrough in confined geometries. When a bed of pellets is confined in a rigid container, packing heterogeneities near the wall lead to faster flow around the periphery of the bed (<i>i.e.</i>, wall channeling). Wall-channeling effects have long been considered negligible for beds which hold more than 20 pellets across; however, the present work shows that neglecting wall-channeling effects on dispersion can yield significant errors in model predictions. There is a fundamental gap in understanding the mechanisms which control wall-channeling driven dispersion. Furthermore, there is currently no way to predict wall channeling effects a priori or even to identify what systems will be impacted by it. This dissertation aims to fill this gap using both experimental measurements and simulations to identify mechanisms which cause the plug-flow assumption to fail.</div><div><br></div><div>First, experimental evidence of wall-channeling in beds, even at large bed-to-pellet diameter ratios (<i>d</i>_bed/<i>d</i>_p=48) is presented. These experiments are then used to validate a method for accurately extracting mass transfer coefficients from data affected by significant wall channeling. The relative magnitudes of wall-channeling effects are shown to be a function of the adsorption/adsorbate pair and geometric confinement (<i>i.e.</i>, bed size). Ultimately, the axially disperse plug-flow model fails to capture the physics of breakthrough when nonplug-flow conditions prevail in the bed.</div><div><br></div><div>The final chapter of this dissertation develops a two-dimensional (2-D) adsorption model to examine the interplay of wall-channeling and adsorption kinetics and the adsorbent equilibrium capacity on breakthrough in confined geometries. The 2-D model incorporates the effect of radial variations in porosity on the velocity profile and is shown to accurately capture the effect of wall-channeling on adsorption behavior. The 2-D model is validated against experimental data, and then used to investigate whether capacity or adsorption kinetics cause certain adsorbates to exhibit more significant radial variations in concentration compared than others. This work explains channeling effects can vary for different adsorbate and/or adsorbent pairs—even under otherwise identical conditions—and highlights the importance of considering adsorption kinetics in addition to the traditional <i>d</i>_bed/<i>d</i>_p criteria.</div><div><br></div><div>This dissertation investigates key gaps in our understanding of fixed-bed adsorption. It will deliver insight into how these missing pieces impact the accuracy of predictive models and provide a means for reconciling these errors. The culmination of this work will be an accurate, predictive model that assists in the simulation-based design of the next-generation atmospheric revitalization system for humans’ journey to Mars.</div>