Browsing by Subject "devices"
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Item Addressing the Consensus Problem in Real-time Using Lightweight Middleware on Distributed Devices(2012-10-19) Hall, Keith AntonWith the advent of the modern technological age, a plethora of electronic tools and devices are available in numbers as never before. While beneficial and ex-ceedingly useful, these electronic devices require users to operate them. When designing systems capable of observing and acting upon an environment, the number of devices can become unmanageable. Previously, middleware sys-tems were designed for large-scale computational systems. However, by apply-ing similar concepts and distributing logic to autonomous agents residing on the devices, a new paradigm in distributed systems research on lightweight de-vices is conceivable. Therefore, this research focuses upon the development of a lightweight middleware that can reside on small devices enabling the capabil-ity for these devices to act autonomously. In this research, analyses determined the most advantageous methods for solving this problem. Defining a set of requirements for the necessary middle-ware as well as assumptions for the environment and system in which it would operate achieved a proper research focus. By utilizing concepts already in ex-istence such as peer-to-peer networking and distributed hash tables, devices in this system could communicate effectively and efficiently. Furthermore, creat-ing custom algorithms for communicating with other devices, and collaborating on task assignments achieved an approach to solving the consensus problem in real time. The resulting middleware solution allowed a demonstration to prove the effi-cacy. Using three devices capable of observing the environment and acting up-on it, two tests highlighted the capabilities of the consensus-finding mechanism as well as the ability of the devices to respond to changes in the environment autonomously.Item Computational Study of the Development of Graphene Based Devices(2012-02-14) Bellido Sosa, EdsonGraphene is a promising material for many technological applications. To realize these applications, new fabrication techniques that allow precise control of the physical properties, as well as large scale integration between single devices are needed. In this work, a series of studies are performed in order to develop graphene based devices. First, using MD simulations we study the effects of irradiating graphene with a carbon ion atom at several positions and energies from 0.1 eV to 100 keV. The simulations show four types of processes adsorption, reflection, transmission, and vacancy formation. At energies below 10 eV the dominant process is reflection, between 10 and 100 eV is adsorption, and between 100 eV and 100 keV the dominant process is transmission. Vacancy formation is a low rate process that takes place at energies above 30 eV. Three types of defects were found: adatom, single vacancy, and 5-8-5 defect formed from a double vacancy defect. Also a bottom-up fabrication method is studied, in this method, the controlled folding of graphene structures, driven by molecular interactions with water nanodroplets, is analyzed considering the interactions with substrates such as SiO2, HMDS and IPA on SiO2. When the graphene is supported on SiO2, the attraction between graphene and the substrate prevents graphene from folding but if the substrate has HMDS or IPA, the interaction between graphene and the substrate is weak, and depending on the geometry of the graphene structure, folding is possible. Finally, to evaluate the characteristics of graphene based devices, we model the vibrational bending modes of graphene ribbons with different dimensions. The resonant frequencies of the ribbons and relations between the size of the ribbon and their resonant frequencies are calculated. The interaction of a graphene vibronic device with water and IPA molecules are simulated and demonstrate that this device can be used as a sensitive vibronic molecular sensor that is able to distinguish the chemical nature of the detected molecule. Also, the electrical properties of the graphene vibronic with armchair and zigzag border are calculated; the latter has the potential to generate THz electrical signals as demonstrated in this work.Item Critical components for novel direct cardiac compression device(2009-05-15) Harrison, Jr., Lewis D.According to the American Heart Association, there are currently 5 million Americans diagnosed with congestive heart failure and that number is steadily increasing (AHA, 2003). The alarming problem of congestive heart failure and other related medical complications has created a need for devices that not only assist the heart but also help the heart to grow and remodel back to its normal configuration. Currently, there are several direct cardiac compression devices (DCCDs) that do assist the heart, however, they do not help the heart to grow and remodel correctly. Dr. John C. Criscione of Texas A&M University has proposed a novel DCCD, in which the compression of the device reinforces the natural curvature of the heart, helping it to grow and remodel correctly. It is hypothesized that with the support of the device, the cells of the heart will be stimulated to grow and remodel back to their normal size and return to their proper function. Two key components necessary to the novel DCCD were designed and constructed for this study. The first component was an adjustable outer shell which enabled the device to become smaller as the failing heart returned to normal size. The second component was an inflatable inner membrane that applies direct pressure to the outer wall of the heart in a way that promotes physiological stress and strain patterns.