A. James Clark School of Engineering

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

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13C and 15N Metabolic Flux Analysis on the Marine Diatom Phaeodactylum tricornutum to Investigate Efficient Unicellular Carbon and Nitrogen Assimilation Mechanisms
(2013) Zheng, Yuting; Sriram, Ganesh; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Photosynthesis is indispensable in carbon cycling and obtaining renewable carbon. Operated by cyanobacteria, algae and plants, this process provides reduced carbon and molecular oxygen, consumes atmospheric CO₂ and harnesses solar energy. Photosynthesis is also central to the production of biofuels. Diatoms, a class of marine algae, contribute 20% to 40% of global photosynthetic productivity despite surviving in CO₂-depleted and nitrogen-limited environments. This makes diatoms ideal models to study efficient photosynthetic, specifically carbon concentrating mechanisms (CCM). It has been long debated that whether the unicellular marine diatom Phaeodactylum tricornutum operates a CCM, and whether the CCM is biophysical or biochemical (C4) in nature, with existing (circumstantial) experimental evidence divided amongst the two possibilities. Through isotope labeling experiments (ILE) and metabolic flux analysis (MFA), we provide for the first time significant, direct evidence for a biochemical CCM and the potential combined operation of a biochemical and a biophysical CCM. Additionally, we shed light on how genes regulating this complex process respond to critical environmental variables. Furthermore, we report the use of isotope-assisted metabolic flux analysis to study organic carbon (especially glucose) assimilation in P. tricornutum. Our steady state ILEs reveal glucose assimilation under light and potentially which genes may be responsible for glucose metabolism. We then studied nitrogen (mainly urea) assimilation through instationary 15N and 13C labeling experiments, to find indications of an unusual pathway of urea assimilation. Gene expression trends under various environmental conditions suggest the possible participation of the urea cycle in assimilating nitrogen in P. tricornutum, and how this metabolically differs from nitrate and ammonium assimilation. We anticipate that this work will not only improve understanding of unicellular C4 CCMs, but provide insights to explain the ecological success of diatoms in adapting to challenging environments.
2-DIMENSIONAL ZEOLITES FOR ADSORPTIVE DESULFURIZATION
(2018) Fang, Jingyu; Liu, Dongxia; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The removal of sulfur-containing compounds from transportation fuels is of growing urgency due to the increasingly government stringent regulations. Adsorptive desulfurization at ambient conditions is a promising strategy for sulfur-containing compound removal compared to traditional hydrodesulfurization (HDS) that requires high temperature and pressure. In this thesis, we studied zeolite adsorbents for adsorptive desulfurization of model fuels. Three zeolite frameworks (MFI, MWW and FAU) in both 2-dimensional (2D) and 3D structures were synthesized and ion-exchanged to both proton-form and Ag+-form. The adsorption of thiophene and benzothiophene, respectively, in n-octane was done using both H+- and Ag+-form zeolites in both 2D and 3D structures. The results show that 2D zeolites have high adsorption capacity than 3D analogues in removal of benzothiophene. The Ag+-form zeolites increase the adsorption capacity compared with that of H+-form. In terms of zeolite framework effects, MWW zeolites possesses the highest adsorption capacity.
2021 Annual Report - Center for Engineering Concepts Development
(2021-10-01) Anand, Davinder; Hazelwood, Dylan
CECD is twenty-one years old and continues to be a platform for experimenting with new ideas in engineering research and education with special attention to the impact of engineering on society. I’m pleased to report that we continue to be supported by ARL, NSWC-IHEODTD, the State of Maryland, and the Neilom Foundation. One hundred guests helped us celebrate our twenty years of activities highlighting innovative activities of contemporary interest that benefit the economic welfare of the State of Maryland and the Nation. This report provides a brief overview of those accomplishments as well as ongoing activities that bring great credit to our faculty and students that comprise CECD.
A 2D Nondestructive Inspection Method to Detect a Through Crack by, Electrostatic Boundary Measurements
(1996) Berenstein, Carlos A.; Chang, Der-Chen; Wang, Emei; ISR
A detailed procedure is proposed to find the position and length of a linear crack originating at the boundary of a 2-d object by means of electrostatic boundary measurements.
3D ENGINEERING OF VIRUS-BASED PROTEIN NANOTUBES AND RODS: A TOOLKIT FOR GENERATING NOVEL NANOSTRUCTURED MATERIALS
(2018) Brown, Adam Degen; Culver, James N; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Technological innovation at the nanometer scale has the potential to improve a wide range of applications, including energy storage, sensing of environmental and medical signals, and targeted drug delivery. A key challenge in this area is the ability to create complex structures at the nanometer scale. Difficulties in meeting this challenge using traditional fabrication methods have prompted interest in biological processes, which provide inspiration for complex structural organization at nanometer to micrometer length scales from self-assembling components produced inexpensively from common materials. From that perspective, a system of targeted modifications to the primary amino acid structure of Tobacco mosaic virus (TMV) capsid protein (CP) has been developed that induces new self-assembling behaviors to produce nanometer-scale particles with novel architectures. TMV CPs contain several negatively charged carboxylate residues which interact repulsively with those of adjacent CP subunits to destabilize the assembled TMV particle. Here, the replacement of these negatively charged carboxylate residues with neutrally charged or positively charged residues results in the spontaneous assembly of bacterially expressed CP into TMV virus-like particles (VLPs) with a range of environmental stabilities and morphologies and which can be engineered to attach perpendicularly to surfaces and to display functional molecular patterns such as target-binding peptide chains or chemical groups for attachment of functional targets. In addition, the distinct electrostatic surface charges of these CP variants enable the higher-level coassembly of TMV and VLP into continuous rod-shaped nanoparticles with longitudinally segregated distribution of functionalities and surface properties. Furthermore, the unique, novel, environmentally responsive assembly and disassembly behaviors of the modified CPs are shown to act as simple mechanisms to control the fabrication of these hierarchically structured functional nanoparticles.
3D Fast Geometric Collision Avoidance Algorithm (FGA) and Decision-Making Approach based on the Balance of Safety and Cost for UAS
(2021) lin, zijie; Xu, Mumu; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Unmanned Aircraft System (UAS) is a fast-growing industry with extensive economic implications and would be integrated into the national airspace system (NAS), which requires UAS to have the efficient sense and avoidance capability. This thesis develops a fast geometry-based algorithm FGA which shortens the collision avoidance computation time, path length and balances the probability of safety and energy cost by calculating and giving UAS proper selective avoidance starting time tc, meaning the last possible point for the UAS to avoiding the potential threaten and itis based on the UAS kinematic, conflicts likelihood map, and navigation constraints. This operation enables the update path to be as close as possible to the UAVs resume designed path, decreasing the length of path variation and the corresponding time cost. In comparison to a current geometry method, the sampling-based method and the search algorithm, the FGA algorithm shows 40% to 90% of reduction in computational time and length of path for the same obstacle avoidance scenarios. Quantitative analysis of the efficiency by different avoiding trigger times is also provided. FGA with critical avoidance time tc not only could improve the geometry methods, but also could be used for (1) research on the bounds of general geometry based collision avoidance, and (2) solving the multiple obstacles avoidance problem.For a scenarios with crowded obstacles which cannot be avoided at the same time, an applicable algorithm for obstacles classification is provided. It divides the obstacles into small groups with different urgent levels by their critical avoidance trigger time tc, and then avoids them in sequence. Simulation validates the efficiency of this application. Extremely difficult obstacle avoidance such as the UAV working under maneuver limitation and the obstacles are time-variant are discussed and solved in the following chapters. Monte Carlo simulation, statistical method and Machine learning algorithms especially the supervised logistic learning methods are implemented later to analyze the weight of the factors such as sensor detection distance, ratio of the speed, number of obstacles, which have impacts on the geometric based obstacle avoidance methods. Finally, flight missions in an aircraft simulator and the hardware fixed-wing aircraft experiments validate the algorithm effectiveness with successful results.
3D IMAGE ANALYSIS OF CT DATA OF CONCRETE CYLINDER SUNDERGOING DELAYED ETTRINGTIE FORMATION
(2019) Shi, Kuo; Amde, Amde M; Livingston, Richard A; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The strains in a concrete caused by delayed ettringite formation (DEF) are conventionally expressed in terms of the one-dimensional linear expansion. However, concrete is not a homogeneous material, and differences in the volume change between the inert aggregates and the reactive cement paste will produce variations in local displacements that cannot be detected by the linear expansion variable. With CT slices offered by Simultaneous neutron and X-ray computed tomography (SNXCT), this thesis applies image analysis algorithms to quantify the distortion of cylinder over time due to delayed ettringite formation. The research reported in this thesis concerned the development of several MATLAB programs to apply image analysis algorithms to quantify the distortion of cylinder over time in terms of summary variables. These included mean radial expansion, deviation from circularity, vertical tilt angle and rotation, void area fraction and the displacement of microbead internal reference points.
3D Integration, Temperature Effects, and Modeling
(2005-05-02) Parker, Latise; Goldsman, Neil; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Practical limits to device scaling are threatening the growth of integrated circuit (IC) technology. A breakthrough architecture is needed in order to realize the increased device density and circuit functionality that future high performance ICs demand. 3D integration is being considered as this breakthrough architecture. In this thesis, the limits to scaling are noted and the feasibility of overcoming these limits using 3D integration is presented. The challenges and considerations, most notably dangerously high chip temperatures, are provided. To address the temperature concern, a mixed-mode simulator that calculates temperature as a function of position on chip is detailed. The simulator captures the important link between individual device and full chip heating. Lastly, circuit simulations and lab experiments are performed to experimentally validate the claims that differences in device activity on chip leads to dangerously high local and overall chip temperatures.
3D Multimodal Image Registration: Application to equine PET and CT images
(2017) Regani, Sai Deepika; Chellappa, Rama; Beylin, David; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Positron Emission Tomography (PET) is being widely used in veterinary medicine in recent years. Although it was limited to small animals because of its classical design and the large amount of radionuclide doses required, PET imaging in horses became possible with the introduction of a portable PET scanner developed by Brain Biosciences Inc. It was observed that this new modality could capture abnormalities like lesions that Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and other modalities could not. Since 2016, PET imaging in horses is being studied and analysed. While PET provides functional information characterizing the activity of lesions, it is useful to combine information from other modalities like CT and match the structural information to develop an accurate spatial representation of the data. Since biochemical changes occur much earlier than structural changes, this helps detect lesions and tumours during the early stages. Multimodal image registration is used to achieve this goal. A series of steps are proposed to automate the process of registration of equine PET and CT images. Multimodal image registration using landmark-based and intensity-based techniques are studied. It is observed that a few tissues are not imaged in the PET, which makes image segmentation, an important preprocessing step in the registration process. A study of the segmentation algorithms relevant to the field of medical imaging is presented. The performance of segmentation algorithms improved with the extent of manual interaction and intensity-based registration gave the smallest time complexity with reasonable accuracy.
3D PRINTED MULTILAYERED / INTERFACIAL SCAFFOLDS FOR OSTEOCHONDRAL REGENERATION
(2021) choe, Robert; Fisher, John P; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Osteoarthritis is a highly prevalent rheumatic musculoskeletal disorder that primarily affects the knee joint. This disease is characterized by the progressive breakdown of the articular cartilage and remodeling of the subchondral bone in the synovial joint. Repetitive overloading perpetuates the damage to the affected cartilage and undermines the structural integrity of the osteochondral unit. Despite much research in osteochondral tissue engineering, no particular strategy has stood out as a potential alternative to conventional treatment options. One major issue that arises during osteochondral regeneration is that the defect site is exposed to a significant physiological load. To overcome these challenges, various tissue engineering strategies have been employed to design multiphasic osteochondral scaffolds that recapitulate layer-specific biomechanical properties. However, multilayered scaffolds have failed to fully satisfy the mechanical requirements to persists within the osteochondral defect. Through the use of extrusion-based bioprinting, we attempt to fabricate a biphasic osteochondral scaffold with improved load-bearing properties and a mechanically strong interface.
3D Wavelet-Based Video Codec with Human Perceptual Model
(1999) Gu, Junfeng; Baras, John S.; ISR; CSHCN
This thesis explores the use of a human perceptual model in video compression, channel coding, error concealment and subjective image quality measurement.
The perceptual distortion model just-noticeable-distortion (JND) is investigated. A video encoding/decoding scheme based on 3D wavelet decomposition and the human perceptual model is implemented. It provides a prior compression quality control which is distinct from the conventional video coding system. JND is applied in quantizer design to improve the subjective quality ofcompressed video.
The 3D wavelet decomposition helps to remove spatial and temporal redundancy and provides scalability of video quality. In order to conceal the errors that may occur under bad wireless channel conditions, a slicing method and a joint source channel coding scenario that combines RCPC with CRC and uses the distortion information toallocate convolutional coding rates are proposed. A new subjective quality index based on JND is proposed and used to evaluate the overall performance at different signal to noise ratios (SNR) and at different compression ratios.
Due to the wide use of arithmetic coding (AC) in data compression, we consider it as a readily available unit in the video codec system for broadcasting. A new scheme for conditional access (CA) sub-system is designed based on the cryptographic property of arithmetic coding. Itsperformance is analyzed along with its application in a multi-resolution video compression system. This scheme simplifies the conditional access sub-system and provides satisfactory system reliability.
3D-PRINTED POLYSTYRENE FOR CELL CULTURE
(2019) Lerman, Max Jonah; Fisher, John P; Gillen, Greg; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Efficient methods to expand stem cells ex vivo hold significant promise in many clinical applications. For example, hematological malignancies account for nearly 10% of cancer related deaths in the United States of America and frequently require a transplant to successfully treat the disease. Ex vivo expanded hematopoietic stem cells (HSCs) could help narrow treatment gaps; however, generating viable dosages of HSCs currently fall short of expectations with difficulties in expanding HSCs and the loss of cellular multipotency. Coculture with mesenchymal stem cells (MSCs) aims to provide the necessary intercellular signaling to counteract monoculture deficiencies. Typically, achieving these and other clinical goals have relied on 2D polystyrene (PS) as the fundamental substrate for cell culture. With the emergence of 3D printing, improved biomimicry with 3D culture models are becoming widely available. In this dissertation, we develop a 3D PS culture substrate for adherent and non-adherent cells, working towards a model for the bone marrow niche. To achieve this goal, the objectives of the work were to: (1) develop a 3D printing method for PS and surface functionalization strategy to facilitate extracellular matrix protein and MSC adhesion, (2) assess the effects of the underlying surface functionality on osteogenic differentiation under static and dynamic conditions, and (3) validate the culture model successfully cultures multiple cell types with a model non-adherent cell line, demonstrating validity and translatability as a bone marrow niche model. In converting PS from a 2D culture platform to a 3D printed one, we take steps to increase the biomimicry of in vitro cell culture without sacrificing fundamental PS properties (e.g. optical clarity, cost-effectiveness, disposability). Continued development and of the model would see an efficient method for studying the complex bone marrow niche with applications in pharmacology and cancer diagnostics.
Ab initio determination of kinetics for atomic layer deposition modeling
(2014) Remmers, Elizabeth; Adomaitis, Raymond A; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
A first principles model is developed to describe the kinetics of atomic layer deposition (ALD) systems. This model requires no fitting parameters, as it is based on the reaction pathways, structures, and energetics obtained from quantum-chemical studies. Using transition state theory and partition functions from statistical mechanics, equilibrium constants and reaction rates can be calculated. Several tools were created in Python to aid in the calculation of these quantities, and this procedure was applied to two systems- zinc oxide deposition from diethyl zinc (DEZ) and water, and alumina deposition from trimethyl aluminum (TMA) and water. A Gauss-Jordan factorization is used to decompose the system dynamics, and the resulting systems of equations are solved numerically to obtain the temporal concentration profiles of these two deposition systems.
ABNORMAL GRAIN GROWTH IN MAGNETOSTRICTIVE GALFENOL ROLLED SHEET
(2011) Chun, Hyunsuk; Flatau, Alison B; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Highly textured Fe-Ga (Galfenol) rolled sheet with Cube (100)<100> or Goss (110)<100> preferred orientation is under investigation to provide easy magnetization, enhanced magnetostrictive performance and a cost-effective option for production of these alloys for use in applications as sensors and actuators. In this study, 1-2.5% NbC added Galfenol rolled sheet was used because NbC particles enhance the rollability of and abnormal grain growth (AGG) in polycrystalline Galfenol rolled sheet. Driving forces, due to grain boundary energy, surface energy, deformation energy and magnetic fields are generally considered to explain grain growth phenomena. In this dissertation, the effect on grain boundary energy for influencing AGG was studied for the case of high temperature annealing at 1200°C. Both Coincident Site Lattice (CSL) and High Energy Grain Boundary (HEGB) models were investigated as possible mechanisms to explain the contribution of grain boundary energy to Goss-textured AGG. Results support the HEGB model as a suitable model for the observed development of Goss-textured AGG in Galfenol rolled sheet. Next, the effect of deformation energy on AGG was studied by using tension annealing and strain annealing methods in the temperature range of 900°C to 1100°C. This study was built on results from studies of grain boundary energy on other alloys. For the tension annealing investigation, Galfenol rolled sheet was simultaneously subjected to tensile loading during high temperature annealing. No AGG was observed from the tension annealing method. For the strain-annealing investigation, homogeneously recrystallized Galfenol rolled sheet with a taper was subjected to tensile loading under different strain rates and post-strain high temperature anneal conditions to investigate the resultant grain growth phenomena. Different grain growth modes, including Cube- and Goss-textured AGG, were observed in this study. Assessment of the extent of AGG resulting from these was conducted using Electron Backscattering Diffraction (EBSD) patterns that were captured and analyzed using Orientation Imaging Microscope (OIM) software to obtain Inverse Pole Figures (IPF) and Orientation Distribution Function (ODF). Additionally, Ga loss, which lowers the magnetostrictive properties, under different conditions was investigated by Electron Probe Micro Analyzer (EPMA). No significant Ga loss was observed during the annealing process at 1000°C, however, about 2% Ga loss was observed during the annealing process at 1100°C and 1200°C in the areas with a high density of grain boundaries.
Abort Trajectories for Manned Lunar Missions
(2007-01-22) Beksinski Jr, Edward David; Lewis, Mark; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
With NASA's renewed focus towards a permanent human presence on the moon, comes the development of the Crew Exploration Vehicle. Unforeseen circumstances can induce emergency situations necessitating contingency plans to ensure crew safety. It is therefore desirable to define the feasibility of a direct abort from an outbound translunar trajectory. Thus an astrodynamic model for lunar transfer has been developed to allow for characterization of the abort feasibility envelope for conceivable transfer orbits. In addition the model allows for several trade studies involving differently executed abort options, factoring in fuel margins. Two optimization schemes were utilized; one to expedite return via any fuel in excess of that required for the abort, and one to explore the boundary region of direct abort infeasibility envelope searching for plausible abort trajectories. The characterization and optimization of translunar abort trajectories for the Crew Exploration Vehicle can ensure increased crew survivability in emergency situations.
Absolute Stability Theory, Theory, and State-Space Verification of Frequency-Domain Conditions: Connections and Implications for Computation
(1997) Chou, Y.S.; Tits, A.L.; Balakrishnan, V.; ISR
The main contribution of the paper is to show the equivalence between the following two approaches for obtaining sufficient conditions for the robust stability of systems with structured uncertainties: (i) apply the classical absolute stability theory with multipliers; (ii) use the modern theory, specifically, the upper bound obtained by Fan, Tits and Doyle [IEEE TAC, Vol. 36, 25-38]. In particular, the relationship between the stability multipliers used in absolute stability theory and the scaling matrices used in the cited reference is explicitly characterized. The development hinges on the derivation of certain properties of a parameterized family of complex LMIs (linear matrix inequalities), a result of independent interest. The derivation also suggests a general computational framework for checking the feasibility of a broad class of frequency- dependent conditions, and in particular, yields a sequence of computable ﲭixed- -norm upper bounds , defined with guaranteed convergence from above to the supremum over frequency of the aforementioned upper bound.
Accelerated Imaging Using Partial Fourier Compressed Sensing Reconstruction
(2016) Chou, Chia-Chu; Babadi, Behtash; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Accelerated imaging is an active research area in medical imaging. The most intuitive way of image acceleration is to reconstruct images from only a subset of the whole raw data space, so that the acquisition time can be shortened. This concept has been formalized in recent years, and is known as Compressed Sensing (CS). In this dissertation, we developed a new image reconstruction method, Partial Fourier Compressed Sensing (PFCS), which combines the advantages of partial Fourier transform and compressed sensing techniques. Then, we explore its application on two imaging modalities. First, we apply PFCS to Electron Paramagnetic Resonance Imaging (EPRI) reconstruction for the purpose of imaging the cycling hypoxia phenomenon. We begin with validating PFCS with the prevailing medical acceleration techniques using CS. Then, we further explore its capability of imaging the oxygen distribution in the tumor tissue. Our results show that PFCS is able to accelerate the imaging process by at least 4 times with-out losing too much image resolution in comparison to conventional CS. Further, the ox-ygen map given by PFCS precisely captures the oxygen change inside the tumor tissue. In the second part, we apply PFCS to 3D diffusion tensor image (DTI) acquisition. We develop a new sampling strategy specified to diffusion weighted images and optimize the reconstruction cost function for PFCS. The results show that PFCS can reconstruct the accurate color FA map using only 30% of the k-space data. Moreover, PFCS can be further combined with Echo-Planar Imaging (EPI) to achieve an even faster acquisition speed. In summary, PFCS is shown to be a promising image acceleration method in medical imaging which can potentially benefit many clinical applications.
ACCELERATED SELF-ASSEMBLY OF PEPTIDE-BASED NANOFIBERS USING NANOMECHANICAL STIMULUS
(2010) Chang, Jonathan Paul; Seog, Joonil; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
One-dimensional nanostructures are ideal building blocks for functional nanoscale assembly. Peptide-based nanofibers have great potential for building smart hierarchical structures due to their tunable structures at a single residue level and their ability to reconfigure themselves in response to environmental stimuli. In this study, it was observed that a pre-adsorbed silk-elastin-based protein polymer self-assembled into nanofibers through a conformational change on the mica substrate. Furthermore, using atomic force microscopy, it was shown that the rate of the self-assembling process was significantly enhanced by applying a nanomechanical stimulus. The orientation of the newly grown nanofiber was mostly perpendicular to the scanning direction, implying that the new nanofiber assembly was locally activated with a directional control. The method developed as a part of this study provides a novel way to prepare a nanofiber patterned substrate using a bottom-up approach.
Access Scheduling and Controller Design in Networked Control Systems
(2005-10-05) Zhang, Lei; Hristu-Varsakelis, Dimitrios; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
A Networked Control System (NCS) is a control system in which the sensors and actuators are connected to a feedback controller via a shared communication medium. In an NCS, the shared medium can only provide a limited number of simultaneous connections for the sensors and actuators to communicate with the controller. As a consequence, the design of an NCS involves not only the specification of a feedback controller but also that of a communication policy that schedules access to the shared communication medium. Up to now, this task has posed a significant challenge, due in large part to the modeling complexity of existing NCS architectures, under which the control and communication design problems are tightly intertwined. This thesis proposes an alternative NCS architecture, whereby the plant and controller choose to ``ignore'' the actuators and sensors that are not actively communicating. This new architecture leads to simpler NCS models in which the design of feedback controller and communication polices can be effectively decoupled. In that setting, we propose a set of medium access scheduling strategies and accompanying controller design methods that address a broad range of stabilization, estimation, and optimization problems for a general class of NCSs. The performance of the proposed methods is illustrated through a set of simulations and hardware experiments.
ACCESSIBILITY BASED EVALUATION OF COASTAL RURAL COMMUNITIES’ VULNERABILITY TO COASTAL FLOODING AND THEIR ADAPTATION OPTIONS
(2022) Yahyazadeh Jasour, Zeinab; Reilly, Allison C; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Global climate change and sea-level rise will cause significant risks to coastal communities. To make inclusive and cost-effective adaptation planning decisions, we need to understand who may be impacted and when. Currently, planning literature generally focuses on housing impacts; when will a house be inundated, and what adaptation strategies are useful to keep a house habitable? Housing, though, is only one of many types of infrastructures people need to reside in an area. Reliable roads are another. This dissertation conducts an analysis of parcel-level impacts of SLR on local residents’ ability to reach key amenities such as emergency services, grocery stores, and schools. Furthermore, it strategically evaluates where road protection should be implemented so that access is maintained in an equitable manner. Next, I use the accessibility analysis to identify the important roads for gathering high-resolution flood data to improve the accuracy of the analysis. I use Dorchester County, Maryland, U.S., as a case study. It is an extremely low-lying rural county and is expected to shrink in half by the end of the century due to SLR. The results from the case study indicate that some parcels are not expected to be inundated by SLR but are expected to experience accessibility impacts. Road protection appears to be a temporary strategy that can buy time for long-term adaptation strategies such as relocation. However, the protection strategies should be cautiously selected based on decision-makers priorities. The insight obtained by this dissertation highlights that when policy and decision-makers are deciding among adaptation strategies, they need to reach some level of consensus about assumptions for which a possible future is planned, and also the trade-off between increasing accessibility levels and balancing the distribution of accessibility among different demographic groups.

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