VictorJuiz/thesis huggingface dataset:
Boundary layer dynamic soaring for autonomous aircraft [electronic resource] : design and validation
Keywords: Aeronautics and Astronautics

Dynamic soaring is a flight technique used by albatrosses and other large seabirds to extract energy from wind gradients in the atmospheric boundary layer over the ocean. This technique enables them to fly for extended periods without flapping their wings, in some documented cases circumnavigating the globe. This work examines the application of dynamic soaring to propulsion of small unmanned aerial vehicles (UAVs). First, the equations of motion were derived and the energy transfer mechanisms were explained for a vehicle flying in a spatially and temporally varying wind field. Next, a robust and efficient dynamic soaring trajectory optimization method that forms the foundation for the remainder of the research was outlined. This method was used to solve for optimal periodic trajectories through a number of different wind fields. It was also used to investigate UAV designs that have the ability to extract electrical energy from their environment and store it on-board, allowing operations during lulls in the wind. Vehicle speed polars were generated that show the maximum cross-country speed achievable as the a function of the wind speed and the cross-country flight direction. The method of isochrones was applied to the long-range routing of dynamic soaring vehicles across the ocean by combining vehicle speed polars with satellite based ocean wind measurements. As part of this work, a small UAV, dubbed Mariner, was designed to demonstrate autonomous boundary layer dynamic soaring over water. The objective of the UAV design problem was to minimize the required reference wind speed. Constraints were imposed on vehicle size and weight, and careful attention was paid to stability and control requirements imposed by the optimal trajectories. Sensors and sub-systems were specified to allow for accurate state estimation in close proximity to the water surface. Experimentally, a small off-the-shelf airframe was flown to aid development of Mariner's flight control hardware and software. An extended Kalman filter (EKF) was implemented for vehicle state and wind estimation and tuned through flight testing. In addition, a novel GPS tracking tag was designed and tested to improve our understanding of albatross dynamic soaring.
Breaking boundaries [electronic resource] : a study of human-mobile interaction
Keywords: Communication

Based on providing visual representation of all functions and key pieces of content, What You See Is What You Get (WYSIWYG) is the current interface design paradigm primarily used in personal computing machines. As we move into a world where computing power continues to increase, and we choose to decrease the physical size of our machines so that they will fit into our pockets, WYSIWYG will break. This research agenda explores a paradigm shift, asking whether users of computing machines can effectively complete tasks without this reliance on visual representation of all functions and information. The two experiments described in this dissertation seek to answer these questions: 1) do visual cues of information and function continue to be required by users in order to complete tasks using mobile devices? 2) are users moving beyond a reliance on recall and recognition memory in human-computer interaction? Furthermore, if these experiments are successful in showing that users no longer need to rely on visual cues in ways similar to the WYSIWYG interactions, can we then describe human-mobile interaction within a memory framework beyond standard recall and recognition? We built two distinct task-based protocols in which participants were asked to work through multi-step tasks, enacting functions and locating pieces of information that we described as being located outside of the physical space of the screen. These functions and pieces of information were not visually represented on the screen. Rather, the participants were primed to understand that the functions and information existed in this non-visual form and could be enacted through particular interaction techniques that referenced the particular, specific space outside of the screen where these items "lived." In the two experiments, participants worked through tasks, either in a WYSIWYG or in a YUMYS paradigm. We took a series of behavioral measurements, including time on task, total number of interactions between the user and the machine in order to complete the task, and successful, correct completion of the tasks. The outcome of this research agenda indicate that the YUMYS interface paradigm will provide a better design framework for mobile designers that will allow mobile users to perceive a decreased workload and increased success as they complete tasks within a YUMYS interface.
Building a learning community [electronic resource] : examining the factors associated with the implementation of professional learning communities
Keywords: Education.

Education research says that collegial work is connected to teachers' sense of efficacy, professional growth and positive student outcomes, but for various social, psychological as well as organizational reasons teachers often face challenges to working together. As a result, efforts to bring teachers together have had uneven success. There is a good deal of research about what effective professional learning communities (PLCs) look like, but less has been done to examine the implementation process. This study combines survey data of 33 New Jersey public schools involved in a state-sponsored PLC training program and case studies of two of those schools in order to trace the factors associated with the implementation of PLCs. The data suggest that a set of predicted variables—vision, community, resources (including time to meet and expertise) and processes —were associated with the development of collegial professional practice, and all of these factors were mediated by principal leadership and the wider distributed leadership structures at the schools. These qualitative findings were corroborated by the survey data from the two case study schools and the larger pool of schools in the program. Other factors such as the state and local contexts of the two case study schools and the leaders' judicious use of their means of control while also supporting teacher autonomy proved to be important factors for these schools as well. While both schools saw even reluctant teachers notice greater depth to their collegial work, there were challenges that remained in terms of scheduling equity and the use of data to support high quality teaching as opposed to state testing preparation.
Capacitive micromachined ultrasonic transducer (CMUT) for chemical detection in air [electronic resource]
Keywords: Mechanical Engineering

Demand for a highly sensitive, accurate, and portable chemical sensor system has been increasing over the recent years for a wide range of applications. For these applications; resonant chemical sensors based on the mass-loading effect (i.e., gravimetric sensors) with chemical functionalization layers are promising candidates. Among them, a capacitive micromachined ultrasonic transducer (CMUT) is a strong candidate with key advantages: 1) it utilizes a thin resonator backed by a vacuum cavity which results in a high quality factor, 2) it has the ability to apply massive parallelism, thereby, increasing its reliability and lowering the motional impedance, and 3) consistent repeatability and reliability in the fabrication process. The development of a CMUT-based chemical sensor encompasses device selection and characterization, oscillation circuit design and implementation, chemical functionalization, and a chemical test. CMUTs with a resonant frequency ranging from 6 MHz to 50 MHz are selected. An oscillation circuit is designed to track the parallel resonant frequency of the CMUT. The CMUT is chemically activated by thin polymer layers (e.g., Polyisobutylene or synthesized polymer) to absorb an analyte of interest. Chemical experimentation reveals that the CMUT-based chemical sensor has a high sensitivity, the capability of analyte identification, and a reliable operation. In order to improve the performance of the CMUT as a mass-loading sensor, the device should have the following elements: a thin plate with a high frequency, low parasitic capacitance, low operating voltage, and a high breakdown voltage. The local oxidation of silicon/wafer-bonding (LOCOS/wafer-bonding) process meets this criteria. The process realizes a CMUT with a quality factor of 400 in air, a resonant frequency up to 50 MHz, and an unprecedented small gap of 40-nm. This thesis presents a highly sensitive chemical sensor based on the CMUT technology with theoretical mass sensitivities of 54.4 zg/Hz/um^2 for the devices operating at 50 MHz. The multi-resonator configuration is more reliable in operation and makes the oscillator circuit easier to design. Since the oscillator circuit was designed with low-frequency (0.2 Hz) noise and an equivalent volume resolution of 21 ppt of Dimethyl methylphosphonate (DMMP); a simulant of Sarin (GB) was achieved. This work thus demonstrates that CMUT technology has great potential for the implementation of chemical sensing systems that are sensitive; yet reliable and portable.
Capacity investment strategies for environmentally responsible firms [electronic resource]
Keywords: Business.

This thesis consists of three essays that analyze the capacity investment strategies for environmentally responsible firms, firms that introduce products into the market which have less impact on the environment or are less harmful to human health than their traditional equivalents, or firms that operate with conventional methods but switch to less carbon-intensive technologies in their new capacity investments due to the climate regulations. In the first essay (co-authored with Erica L. Plambeck), we examine capacity leadership, in which a manufacturer adjusts the timing and level of her own capacity investment in order to motivate noncontractible capacity investment by a supplier. When the firms have common information about the demand distribution and their capacities are complements, the manufacturer can increase the supplier's incentive for capacity investment by building her own capacity early. When the supplier's bargaining strength is moderately high, early capacity investment by the manufacturer strictly increases both firms' expected profits. The manufacturer's optimal level of early capacity increases as the selling price and demand for the end product increase, capacity costs decrease, or she obtains private information that demand is likely to be high. If the supplier's capacity investment is contractible, the manufacturer may still achieve greater expected profit through early capacity investment than a contract. When the firms' capacities are substitutes, early capacity investment by the manufacturer reduces her eventual payment to the supplier and thus the supplier's incentive for capacity investment. Nevertheless, the supplier's capacity cost is sufficiently lower than that of the manufacturer, the manufacturer optimally builds early capacity to signal a high demand forecast. These results may help to explain why several manufacturers of renewable energy and energy-efficient products have built capacity early, before it could be utilized. In the second essay (co-authored with Stefan Reichelstein), we investigate the carbon capture and storage (CCS) technologies for fossil fuel power plants, which offer the potential for significant reductions in carbon dioxide emissions. We examine the break-even value for CCS adoptions, that is, the critical value in the charge for carbon dioxide emissions that would justify investment in CCS capabilities. Our analysis takes explicitly into account that the supply of electricity at the wholesale level (generation) is organized competitively in some U.S. jurisdictions, while in others a regulated utility provides integrated generation and distribution services. For either market structure, we find that emissions charges near 0 per tonne of carbon dioxide would be the break-even value for adopting CCS capabilities at new coal-fired power plants. The corresponding break-even values for natural gas plants are substantially higher, near
Carbon nanotube electronics [electronic resource]
Keywords: Electrical Engineering

In recent years, carbon-based electronics have surfaced as potential candidates for substituting silicon-based logic as scaling continues into the new decade and beyond 20nm technology node. In particular, carbon nanotubes (CNTs) and graphene nanoribbons have received significant attention from the academia as well the industry. Ideal electronic and structural properties of these materials make them suitable for electronic applications. In this work we discuss the basics of CNT growth and device fabrication, explore performance and contact resistance for CNT Field Effect Transistors (CNFETs) based on horizontally-aligned grown CNTs. We provide a physics-based compact model for simulation of CNFETs in a) quantum ballistic and b) semiclassical diffusive regimes. Measuring channel carrier density is essential for extracting key device parameters such as mobility while it can also provide a detailed picture of the underlying quantum mechanics. Since CNTs and nanostructures in general are limited by quantum capacitance, will also provide an Integrated Capacitance Bridge (ICB) for wide temperature-range, high resolution measurements of quantum capacitance in nanostructures with an excitation amplitude smaller than kBT/q.
Carbon nanotube films and microjet cooling devices for thermal management [electronic resource]
Keywords: Mechanical Engineering

The downsizing of electronic devices and the consequent increasing power densities pose thermal management challenges for the semiconductor industry. Since the present thermal solutions limit their cooling capacity, developing new cooling methods for electronic devices has become important. This dissertation presents two types of novel methods for heat dissipation from integrated circuits: One is the use of advanced thermal interface materials, such as carbon nanotubes (CNTs), to increase heat dissipation between the solid and solid surface, such as a chip and heat sink. The second method is the use of a microjet impingement device to improve heat transfer between a liquid and solid in a heat sink. As advanced interface materials, vertically aligned carbon nanotube films are promising because of their unique mechanical and thermal properties. The first part of the dissertation describes the design, fabrication, and testing of CNTs using resonators to characterize their mechanical properties. Discussed in detail is the preparation of carbon nanotubes using different recipes, resulting in varied thicknesses of single-walled carbon nanotube films and multi-walled carbon nanotube films. The measurements of the resonant frequency shifts due to the presence of the CNT films using a laser Doppler vibrometer system result in extracted moduli of 0.5-220 [Mu]m-thick nanotube films varying from 1 to 370 MPa. To show how the physics between the effective modulus and thickness are connected, an analysis for the height dependence of the modulus is provided. After an image analysis is presented, a nanotube dynamics simulation based on tube properties and film morphology is introduced to predict mechanical properties. In addition to discussing the proposed interface materials, the second part of the dissertation describes the design, fabrication and testing of microjet impingement cooling, which display high heat capacities, as an advanced thermal management solution. The design of single-jet and multi-jet arrays with different numbers of diameters, locations, and spacing is discussed. Specifically, this part demonstrates how the microjet hydrodynamics are quantified using two-dimensional images by [Mu]PIV techniques, enabling the reconstruction of the three-dimensional flow field. The results indicate that CNT films offer a mechanical compliance that is suitable for TIM applications and that the microscale liquid jet devices provide quantified flow physics for heat sink applications.
Carbon nanotube transparent electrodes for photovoltaic applications [electronic resource]
Keywords: Materials Science and Engineering

Virtually all solar cells require a transparent and conductive (TC) layer on the top surface that allows sunlight to enter the cell and photoexcited charge to be conducted laterally across the top surface. The impact on power conversion efficiency due to reflection, absorption, resistive losses and lost active area is a reduction by 10 -- 25 %, relative. Historically, doped metal oxides such as tin doped indium oxide (ITO) have been used. In the last several years, however, there has been renewed interest in this area with the development of several new nanostructured materials, many of which have the potential for performance, processing, and cost advantages. In the first portion of this work, we describe TC related efficiency losses in detail for the two major categories of solar cells. For thin film monolithically integrated modules, TC related losses can be as high as 25 % and for standard modules of cell strung together losses are typically 10 -- 15 %. For the purpose of developing new TC materials, we specify the material performance requirements for a competitive TC material and show the expected TC related efficiency losses in photovoltaic (PV) modules for any material of known electrical and optical properties. We then provide an overview of the leading nanostructured materials and show that carbon nanotubes (CNT) have basic optoelectronic material properties that are superior to traditional metal oxides. We exhibit the first demonstration of a highly flexible organic solar cell using carbon nanotube films as the TC. The achieved power conversion efficiency of 2.5 % is comparable to the 3.0 % efficiency of the control device using ITO and the flexibility of the CNT device is far greater. Finally, we detail an in-depth investigation of the electrical properties of carbon nanotube networks in order to determine and understand the performance limitations. For this, we develop a novel method of atomic force microscope (AFM) scratch lithography in order to isolate individual CNT bundles and a novel method of electric force microscopy (EFM) in order to quantitatively measure local contact resistances on the nanoscale between CNT bundles. We measure bundle-to-bundle junction resistance for a range of bundle diameters which reveals a previously unobserved inverse scaling of contact resistance with diameter. Values range from 1 kOhm to 200 kOhm for bundle diameters typical of CNT TC networks. We also measure the resistivity of ropes of bundles and we find that this resistance is very high and limits the conductivity of the CNT TC films studied in this work. The structure property relationships revealed from these measurements clearly show what type of morphology control is necessary for high performance CNT TCs and that increasing tube length and/or decreasing junction resistance are the primary routes for further increases in performance.
Cationic, random-coil protein polymers for free-solution conjugate electrophoresis (FSCE) in microchannels [electronic resource]
Keywords: Bioengineering.

Access to an individual's genetic data, often for a small set of genes, will offer increasing value in medical practice; e.g., in cancer treatment it may be useful to track sequence alterations in oncogenes over time, or even spatially within a tumor. Such applications create a need for rapid, low-cost, scalable technologies for high-accuracy sequencing of human DNA. Some regions of the human genome, particularly repeat-rich loci, are challenging to analyze accurately with short-read, next-gen DNA sequencing technologies. Long-read, high-accuracy sequencing is done now by capillary array electrophoresis (CE), but DNA separations on microdevices are at least 10 times faster and deliver equally long, accurate reads. Free-Solution Conjugate Electrophoresis (FSCE) is a novel method of DNA sequencing ideal for implementation on microfluidic devices, as it obviates the need for viscous polymer solutions to separate DNA. FSCE uses a monodisperse protein "drag-tag", tethered end-on to one terminus of ssDNA fragments, to enable sequencing in free solution. The most difficult aspect of developing FSCE is the creation of long (> 500-amino acid (aa)), totally monodisperse protein drag-tags needed for long reads. Recent studies in FSCE indicated that introducing positive charges in a drag-tag would help to achieve higher hydrodynamic drag without requirements of significantly increasing the size of the drag-tag. In this dissertation, a new family of de novo-designed proteins with intentionally included cationic (Arg) amino acids was designed. A faster and easier purification method combining affinity chromatography and tag-removal was established to create protein polymers with improved monodispersity required for FSCE applications. After rigorous characterization, these novel protein drag-tags were analyzed by free-solution separations and FSCE sequencing. Through these studies, I investigated critical biophysical attributes of positively charged drag-tags important to FSCE performance and identified the limits for inclusion of positive charges in sequences of protein polymer drag-tags for successful FSCE applications. The investigations of two post-Sanger conjugation strategies were also initiated and were proven to enable the utilization of previously unusable larger/higher charged protein drag-tags that suppressed the enzymatic extension when attached to sequencing primers prior to the Sanger reaction.