Browsing by Subject "Sensing"
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Item Analysis and Implementation of an Orientation-Aware Source Localization System with Smart Devices(2014-05-29) Tunon Coronado, Daniel AntonioTarget localization in wireless systems has experienced a great improvement during recent years given the increasing demand for location services by mobile users. Particularly, localization methods based on received signal strength indicator (RSSI) are highly attractive because hardware is readily available and cost-effective. The RSSI-based localization literature generally focuses on the propagation environment sensitivity and overlooks a major factor in signal strength variability: the relative orientation between the source and the receiver. With current advancements in hardware, especially low-cost microelectromechanical sensors, most wireless devices are orientation-aware. This offers an opportunity to enhance the performance of multi-agent localization systems. We propose to include orientation knowledge and the typical antenna radiation pattern asymmetries of the sensing devices into the inference task. We will gather experimental data using Android? smartphones as sensing devices, implement the new orientation-aware algorithm and asses the improvements of our approach in simulations and real-world scenarios. We compare the new scheme with the standard setting where the orientation is unknown. The orientation-aware implementation performs significantly better than the traditional systems in terms of accuracy. These results show that orientation-awareness capabilities should be accounted for whenever possible in tasks of statistical inference. Furthermore, this idea is likely to find applications beyond source localization.Item Cognitive radios : fundamental limits and applications to cellular and wireless local networks(2012-05) Chung, Goochul; Vishwanath, Sriram; Shakkottai, Sanjay; Andrews, Jeffrey; Caramanis, Constantine; Choi, JihwanAn ever increasing number of wirelessly-enabled applications places a very high demand on stringent spectral resources. Cognitive radios have the potential of enhancing spectral efficiency by improving the usage of channels that are already licensed for a specific purpose. Research on cognitive radios involves answering questions such as: how can a cognitive radio transmit at a high data rate while maintaining the same quality of service for the licensed user? There are multiple forms of cognition studied in literature, and each of these models must be studied in detail to understand its impact on the overall system performance. Specifically, the information-theoretic capacity of such systems is of great interest. Also, the design of cognitive radio is necessary to achieve those capacities in real applications. In this dissertation, we formulate different problems that relate to the performance of such systems and methods to increase their efficiency. This dissertation discusses, firstly, the means of "sensing" in cognitive systems, secondly, the optimal resource allocation algorithms for interweave cognitive radio, and finally, the fundamental limits of partially and overly cognitive overlay systems.Item Detecting single-particle insulating collisions in microfluidics as a function of flow rate(2012-12) Nettleton, Elizabeth Grace; Crooks, Richard M. (Richard McConnell); Bard, Allen JThis work presents the first electrochemical observation of single polystyrene microbead collisions with an electrode within a microchannel. We have observed that detecting single microbead collisions is facile with this system. Additionally, we have shown that by increasing flow within the channel, one can increase both the frequency and magnitude of collision signals. This technique may provide a means of signal amplification in future sensing work.Item History and Analysis of Distributed Acoustic Sensing (DAS) for Oilfield Applications(2013-05-15) Kimbell, JeremiahThe inherent nature of distributed acoustic sensing technology is a direct result of two key components: optical fiber and the speed of light. Because the speed of light is constant and optical fiber is an isolated medium, combining the two creates a mechanism insulated from environmental interference that effectively ?moves? at the speed of light. This process is most visible in the telecommunications industry where the technology transports large amounts of data over significant distances at very high speeds. The same factors that make optical fiber excellent for transporting data (high speed and low environmental interference) also make the technology very applicable for precise measuring applications. Because optical fiber is insulated, a change to the fiber will have a pronounced (measurable) effect. These measurable effects manifest themselves as changes in the amount of light that is reflected within the optical fiber. This change in reflected light can be measured and quantified to indicate both the specific location along the fiber where the change in reflection occurred and the magnitude of the change in reflection. Knowing both the location of the affected area and the extent to which the reflection changed allows for precise measuring and subsequently, educated inferences about what caused the changes initially. The ability of optical fiber to detect changes at myriad intervals over long distances has particular appeal for functions involving remote and hard to get to environments. Both of these conditions are inherent to the petroleum industry and provide substantial incentive for investigating DAS for oilfield applications.Item Studies of multicomponent assemblies(2012-12) Long, Samuel Reid; Anslyn, Eric V., 1960-; Iverson, Brent L.This dissertation is divided into three major sections (one on dendrimers, one on tripodal metal ligands and one on a research oriented chemistry curricula) with a primary focus on different types of multicomponent assemblies. In the first chapter, a system is described that used a multicomponent assembly of AT-PAMAM dendrimers and an indicator, carboxyfluorescein, to detect and identify various polyanions at a low micromolar concentration. The system was able to successfully differentiate twelve anions, many of biological interest, including three tricarboxylates. The tricarboxylates were differentiated based primarily on the regiochemistry of the anionic groups. In the second chapter, further studies with AT-PAMAM dendrimers were carried out to provide some understanding of the thermodynamic origins of binding. Utilizing isothermal titration calorimetry, the binding of the dendrimers to large polyanionic dendrons with increasing numbers of charges was studied. Through these studies, the thermodynamic values of the binding events were obtained allowing us to explore the properties of the dendrimers. The cooperativity of the system was measured, and primarily negative cooperativity determined by the entropic contributions was uncovered. As the dendrimers increased in size, the thermodynamic origins of binding were determined to a greater extent by the entropy of binding. In the third chapter, a novel dynamic ligand system for metal binding is described. In the presence of a metal salt, a heterocyclic aldehyde and a secondary amine with two heterocyclic arms reversibly condense to form a hemiaminal with a tripodal metal binding site. This chapter describes studies on the metal binding ability, the variety of metals that will lead to this formation, the effects of anions and the range of aldehydes that can be used are described. Furthermore, the system’s reversibility was explored. Finally, the use of a bistriazole secondary amine was explored. The modular nature of triazole formation could lead to the introduction of additional functionalities. The fourth chapter discusses how the novel ligand system could be used to study the enantiomeric excess (ee) of chiral thiols. Based upon the system’s ability to form a stable hemiaminal thioether, a CD signal could be generated that is proportional to the amount of a particular enantiomer in solution. Using this system, a calibration curve relating CD signal and ee can be generated giving the ee of an unknown solution. In the final chapter, a look at the Freshman Research Initiative will be carried out with a focus on the ability to teach basic skills in an introductory laboratory through research. Four different skills or techniques will be explored through three different FRI streams,x and how they teach the four skills. Finally, analysis of the success of the program, particularly students’ success in the next laboratory course in the sequence, is discussed, and a model for adopting this type of teaching at other universities is given.