Emerging applications for robotic data collection include ocean monitoring, emergency response and urban search and rescue. At the core of these applications is a robot's ability to make informed decisions on incomplete data. This dissertation addresses this problem by developing novel techniques for modeling and estimating structured environments using deep...
As robotic systems become increasingly prevalent in our lives (e.g., by harvesting food, assisting with disaster response and defense, and transporting persons and our goods around the world) there is a growing need to ensure that they can cooperate to achieve their intended goals. Robotic cooperation in the real-world is...
This thesis presents a decentralized communication planning algorithm for cooperative terrain-based navigation (dec-TBN) with autonomous underwater vehicles. The proposed algorithm uses forward simulation to approximate the value of communicating at each time step. The simulations are used to build a directed acyclic graph that can be searched to provide a...
Multi-robot systems are versatile and extremely capable of exploration tasks in complex environments. Increasingly sophisticated planners, which incorporate new features of a multi-robot system, are necessary for the operation of the systems. Marsupial robots are multi-robot systems consisting of a carrier robot (e.g., a ground vehicle), which is highly capable...
In shared autonomy, a robot and human user both have some level of control in order to achieve a shared goal. Choosing the balance of control given to the user and the robot can be a challenging problem since different users have different preferences and vary in skill levels when...
Underwater robots beneath ocean waves can benefit from feedforward control to reduce position error. This thesis proposes a method using Model Predictive Control (MPC) to predict and counteract future disturbances from an ocean wave field. The MPC state estimator employs a Linear Wave Theory (LWT) solver to approximate the component...
Information gathering tasks, such as terrestrial search and rescue, aerial inspection, and marine monitoring, require robotic unmanned systems to make decisions on how to travel within an environment to maximize or minimize a path-dependent information objective function. The distribution of information throughout the environment is the result of various processes,...
Human-robot teams are invaluable for mapping unknown environments, exploring difficult-to-reach areas, and manipulating inaccessible equipment. However, guiding autonomous robots requires dealing with these dynamic domains while synthesizing a significant amount of data and balancing competing objectives. Current mission planning methods often involve manually specifying low-level parameters of the mission, such...
We present a method for decentralized, multi-robot exploration in adverse environments where communication is minimal. A key conceptual feature of our method is enabling implicit coordination between robots by training a Convolutional Neural Network (CNN) as a heuristic for planning using Monte Carlo Tree Search (MCTS). Our method consists of...
Motion planning is a cornerstone of autonomous robots, enabling robots to safely and efficiently perform tasks such as package delivery, infrastructure inspection, and manipulation. However, as the field of robotics matures, robotic systems are being developed that (1) are challenging to analytically model, (2) require computationally expensive model-based controllers, and...
Unmanned aerial vehicle (UAV) technology has grown out of traditional research and military applications and has captivated the commercial and consumer markets, showing the ability to perform a spectrum of autonomous functions. This technology has the capability of saving lives in search and rescue, fighting wildfires in environmental monitoring, and...
While robotic systems may have once been relegated to structured environments and automation style tasks, in recent years these boundaries have begun to erode. As robots begin to operate in largely unstructured environments, it becomes more difficult for them to effectively interpret their surroundings. As sensor technology improves, the amount...
Deep learning has recently revolutionized robot perception in many canonical robotic applications, such as autonomous driving. However, a similar transformation has yet to occur in more harsh environments including underwater and underground. This is due in part to the difficulty in deploying robots in these environments, which lack large real...
There is growing commercial interest in the use of unmanned aerial vehicles (UAVs) in urban environments, specifically for package delivery applications. However, the size, complexity and sheer numbers of expected UAVs makes conventional air traffic management that relies on human air traffic controllers infeasible. To enable UAVs to safely and...
Tensegrity structures are composed of pure compressional elements that are connected via a network of pure tensional elements. The concept of tensegrity promises numerous advantages to the field of robotics. Tensegrity robots are, however, notoriously difficult to control due to their oscillatory nature and nonlinear interaction between the components. Multiagent...
Underwater monitoring and manipulation with autonomous underwater vehicles (AUVs) are active avenues of research in the Field Robotics Community. The purpose of this document is to briefly summarize some of the more promising research applications as well as provide information from four companies working in the area of marine renewable...
We propose three sampling-based motion planning algorithms for generating informative mobile robot trajectories. The goal is to find a trajectory that maximizes an information quality metric (e.g. variance reduction, information gain, or mutual information) and also falls within a pre-specified budget constraint (e.g. fuel, energy, or time). Prior algorithms have...
This work proposes a technique for distributed multi-robot exploration that leverages novel methods of map inference. The inference technique uses observed map structure to infer unobserved map features. The team then coordinates to explore both the inferred and observed portions of the map. Individual robots select exploration poses by accounting...
Mountain search and rescue is a vital form of emergency response to assist people in austere environments (e.g., extreme terrain, poor weather). Volunteer mountain search and rescue teams in the United States have begun adopting consumer- grade unmanned aerial vehicles to assist a variety of tasks (e.g., search, resource delivery);...
Building Information Modeling (BIM) offers a variety of tools to help a wide range of stakeholders in the construction industry. There has been substantial research on the advantages and challenges of implementing BIM for large and medium-sized construction companies; however, there is a dearth of research on the benefits and...
Robots have the potential to protect health care workers, provide patient care, and ultimately save lives in infectious disease outbreaks. Nevertheless, infectious disease outbreak scenarios present unique technological and social challenges for robotics. This work explores what robots can and should do in the fight against infectious diseases. We present...
In this paper, we introduce a novel algorithm for incorporating uncertainty into lookahead planning. Our algorithm searches through connected graphs with uncertain edge costs represented by known probability distributions. As a robot moves through the graph, the true edge costs of adjacent edges are revealed to the planner prior to...
Performing autonomous robotic tasks in the field, such as ocean monitoring and aerial surveillance, requires planning and executing paths in dynamic environments. In these uncertain and changing environments, it is not uncommon to see a large difference between the path planned by the robotic vehicle and the path that the...
The effectiveness of robot autonomy is governed by the ability to make decisions based on online sensor measurements and a prior belief of the environment. Uncertainty in the environment introduces challenges to robotic decision making. This thesis address two key robot decision making problems: exploration and navigation. The robotic exploration...
State-of-the-art personal robots need to perform complex manipulation tasks to be viable in complex scenarios. However, many of these robots, like the PR2, use manipulators with high degrees of freedom. High degrees of freedom are desirable from a functionality standpoint, but make the learning task more difficult by adding a...
Multiagent coordination has many real-world applications such as self-driving cars, inventory management, search and rescue, package delivery, traffic management, warehouse management, and transportation. These tasks are generally character-ized by a global team objective that is often temporally sparse - realized only upon completing an episode. The sparsity of the shared...
Current research into path planning for Unmanned Aerial Vehicles (UAVs) has placed a major focus on accomplishing the goals of various agents while avoiding collisions between each other. However, there has been little focus on whether the planned trajectories are fair for each agent.
This work provides an answer to...
Cephalopod-inspired soft robot arms have been studied as a new type of manipulator. These arms have been proposed for reach and grab tasks, underwater locomotion via swimming and walking, and robotic surgery. However, the capabilities of existing soft arms are limited to simple motions and light loads. Arm design has...
Operating autonomous underwater vehicles (AUVs) near shore is challenging—heavy shipping traffic and other hazards threaten AUV safety at the surface, and strong ocean currents impede navigation when underwater. Predictive models of ocean currents have been shown to improve navigation accuracy, but these forecasts are typically noisy, making it challenging to...
Numerous diseases and injuries can limit a person's ability to perform everyday tasks -- things like getting dressed, bathing, and eating. Anything that requires physical activity can be affected; even simple things like turning on the lights can become difficult or impossible. Until recently, the only way for a person...
This paper presents novel data fusion methods
that enable teams of vehicles to perform target search tasks
without guaranteed communication. Techniques are introduced
for merging estimates of a target’s position from vehicles that
regain contact after long periods of time, and a fully distributed
team planning algorithm is proposed that...
A wide variety of hydrodynamic theories are utilized to approximate a Wave Energy Converter’s (WEC) equation of motion. Numerous theories have been refined in order to improve numerical approximations of WEC dynamics. When incorporating refined hydrodynamic theories into numerical models, there are distinct impacts on WEC rigid body motions, cable...
Expressive motion has been found to be a highly effective tool in communicating intent and motivation in single robot human-robot interaction, but work in exploring how groups of robots can use motion in interactions with humans is relatively nascent. There are many additional complexities to consider expanding from single robot...
Multiagent learning offers a rich framework to address challenging real-world problems such as remote exploration and healthcare coordination, which require autonomous agents to express elaborate interactions. To be effective in such systems, agents must collectively reason about and pursue high-level, long-term, and possibly nebulous objectives while adapting their strategy to...
In this thesis, a new learning algorithm is introduced that is targeted towards individual fairness. In order to be individually fair, mispredictions need to be avoided as each such prediction means the learning algorithm was unfair towards some individual. Therefore, achieving individual fairness implies having a perfect classifier, which is...
The workshop was funded by the National Science Foundation (NSF), OCE Division of Ocean Sciences (Award # 1817257). This report summarizes the key findings, outcomes, and recommendations of the workshop and serves as a draft of the comprehensive roadmap.
The Buddhist discipline known as Yogacara can complement the practice of Psychotherapy by virtue of the former’s concepts that allow individuals to examine their minds in a way that produces beneficial insights regarding one’s mental health problems. Yogacara contains the idea of a storehouse consciousness that is similar to the...
The suffering of animals and the environment due to the advancement of anthropocentric endeavors is undeniable. There is no unitary cause that can account for the “why” of people’s belief in humanities exceptional status compared to animals: Some believe capitalism is the root of disparagement, others believe our scientific prowess...
In this thesis I explore the ways in which twenty-first century Americans have access
to Geoffrey Chaucer and his works. I look at issues surrounding Chaucer within the
canon debate, high school history and literature textbooks, and Chaucer in popular
culture, such as in movies like A Knight's Tale. I...
My thesis, entitled “The Clerk’s Tale: Literal Monstrosities and Allegorical Problems,” argues that Chaucer’s Clerk is engaging both sides of a binary system. The Clerk has situated himself in a precarious position between two major schools of thought in the medieval culture, Franciscan and Dominican; the former promotes the will...
Efficient coordination is desired for multi-robot systems in many scenarios. In this research, we first provide a multi-robot system to help human workers during tree fruit harvest. We present an auction-based method to coordinate a team of self-propelled bin carriers to retrieve fruit bins. Second, we propose a more general...
In this thesis, I aim to bring two ancient spiritual guides into dialogue with each other and with modern psychology: the Bodhisattvacaryāvatāra by Śāntideva of the Mahāyāna Buddhist tradition and The Ladder of Divine Ascent by St. John Climacus of the Christian tradition. I draw from Tibetan Buddhist commentaries on...
This project created a stand-alone unit capable of providing on-board sensing and processing for robotic vehicles. This unit was designed to be compact, lightweight, inexpensive, and adaptable. The goal of this project is to help advance robotics research in mapping and multi-agent coordination by making it easier to equip vehicles...
The Columbia River delivers the greatest amount of freshwater to the coastal ocean along the U.S. Pacific coast. This freshwater forms the Columbia River plume, a mesoscale plume with significant implications on coastal ocean physical, biological, chemical, and geological processes. The plume is transported south and offshore during the upwelling...
In this dissertation, new theory and its applications are developed to predict three properties of complex ecological communities: stability, equilibrium response, and non-equilibrium dynamics. First, a graph-theoretic analysis identifies the interconnections in a complex ecosystem that promote or diminish stability (Chapter 2). The hierarchy of interactions that influences stability and...
The data presented in this report demonstrate significant improvements
in the ability to constrain trace element and Sr isotopic
concentrations in sediments overlying ridge-flank hydrothermal
systems. Improved sampling methods orchestrated by the Integrated
Ocean Drilling Program (i.e., advanced piston coring and
anoxic sample processing) enabled the collection of reactive pore...
Commercially bottled, vitamin C-fortified, cranberry
juice cocktail and cranberry-apple (cranapple) juice
drinks were stored at 5°C under simulated home-use
conditions. Ascorbic acid (AA) and dehydroascorbic acid
(DHA) levels were evaluated over a period of seven days by
high performance liquid chromatography (HPLC). Total
vitamin C content was also determined by...
Dynamic modeling of the atmospheric flight mechanics of a projectile equipped with an uncontrolled internal rotating disk is investigated and a modified projectile linear theory is established. It is shown through modeling of this type of projectile that several coefficients of the epicyclic dynamics are altered, leading to changes in...
Reinforcement learning has made impressive strides in solving problems in challenging domains, but problems are increasingly being described with sparse rewards. Sparse rewards directly reduce the rate at which useful feedback is provided to the learner and make it difficult to distinguish between what specific actions led to the reception...
This study investigates the atmospheric flight dynamics of a munition system and the effect of a tether reel resistance mechanism for limiting the impact that the unreeling process has on the munition system. The munition system consisting of two projectiles connected by a tether line is released from an aircraft...
Overcapacity in the form of excess fishing vessels or effort allocation often arises out of improved economic conditions and/or innovation in fishing methods and is generally associated with species overexploitation. With many fisheries fully or over-exploited, stakeholders are advocating product enhancement to add value to the fishery. A recent innovation...
The dissertation introduces community-based adaptive watershed management (CAWM) as a holistic conservation framework. The CAWM
framework integrates social and ecological suitability to achieve conservation outcomes. The core theoretical concepts consist of adaptive management, adoption-diffusion,
symbolic interactionism, community-based conservation, spatial analysis and watershed management. The CAWM framework is applied to the...
Two light sensitive mutants of the green alga Scenedesmus obliquus strain D₃ have been characterized. The photodynamic nature of their sensitivity has been established, the subchloroplast site of photodamage has been investigated, and their noncarotenogenic character has been verified. The two mutants possess several similarities, although mutant L. S. -41...
Levels of activity of glucose-6-phosphate- , 6-phosphogluconate- , and isocitric- dehydrogenase were measured in the
soluble and particulate fractions of heart, brain and liver at
several ages throughout the development of the chick embryo.
Compared to isocitric dehydrogenase, levels of glucosesphosphate-
, and 6-phosphogluconate- dehydrogenase are generally
low. This suggests...
The population genetic structure of ponderosa pine (Pinus ponderosa Dougi.) in the Willamette Valley of Oregon was investigated. Cones were collected from native stands of ponderosa pine from the Willamette Valley, eastern Oregon, southwest Oregon and the Puget Sound Basin of Washington. Seeds were subjected to isozyme analysis of 12...
Imbalanced deoxyribonucleoside triphosphate (dNTP) pools are mutagenic for DNA synthesis in both intact cells and cell-free replication systems. Almost certainly, such mutagenesis involves competition between correctly and incorrectly base-paired precursors at replication sites. However, there are certain differences between the intact cell and cell-free systems that do not always allow...
Breeding ecology of long-billed curlews in Umatilla and Morrow Counties, Oregon, was studied during the spring and summer of 1978
and 1979. The first curlews were observed in the study areas on 16 and 19 March of 1978 and 1979, respectively. Earliest clutch completion and onset of incubation was on...
This paper will address Oregon's ability to regulate and manage its wetland resources as a means for protecting and enhancing salmon habitat. After identifying the importance of wetland environments the paper will look into OWRF to assess its effectiveness. Ultimately the paper will conclude that OWRF's design is an effective...
This dissertation incorporates coalition formation and probabilistic planning towards a domain-independent automated planning solution scalable to multiple heterogeneous robots in complex domains. The first research direction investigates the effectiveness of Task Fusion and introduces heuristics that improve task allocation and result in better quality plans, while requiring lower computational cost...
Tribal water rights and instream flows for species listed under the Endangered Species Act (ESA) have been a source of tensions in the western United States, particularly when tribes have undetermined water rights to support tribal fisheries listed under the ESA. Understanding the mechanics of past tribal settlements and their...
Commercial and public safety usage of Unmanned Aerial Vehicles in the National Airspace is currently restricted by federal regulation. The Federal Aeronautics Association is interested in modifying the restrictions; however, research is needed to study the human factor and required aptitude for a single human operating multiple UAVs. This Master’s...
This thesis includes a satirical novel and a short analytical reflection on the writing process and the general themes and takeaways from the novel itself. While the analytical reflection appears before the novel in the paper, they can be read in either order. The novel satirizes how people respond to...
This thesis argues for the importance of justice of recognition not only for humans, but the entire non-human world in the face of environmental destruction and climate crisis. The common response to the degradation of the world’s ecological sphere is to act with technological, scientific, and material based responses. However,...
Modern walking robots have shown that dynamic gaits can be achieved without ankle motors. It seems logical that the additional control authority that they provide can be used to improve the stability of the walking gait against foot placement errors caused by low level control. This thesis develops and compares...
Market chain analysis can provide information on distribution of costs and profits to intermediaries and aid in identifying concentrations of market power. There is a paucity of research and limited empirical data on market chains in developing country fisheries, especially small-scale fisheries. With these fisheries dominated by artisanal and subsistence...
This thesis analyzes the ways in which the practices of yoga, mindfulness and meditation can be of benefit to hospice and palliative care practitioners in addressing job-related stress. The research suggests that these contemplative practices can be effective in addressing compassion fatigue among hospice and palliative care professionals. The thesis...
We present concentrations of germanium and silicon in sediment pore waters, basaltic formation fluids,
and bulk sediment from three ridge flank hydrothermal systems (RFHS). Basaltic formation fluids from
warm (>30°C) RFHS have much higher Ge concentrations and Ge:Si molar ratios than overlying sediment
pore waters, requiring seawater-basalt reactions to dominate...
Wave energy is emerging as a new potential source for renewable energy generation. However, wave energy technology is not currently cost competitive with other more mature renewable energy sources such as wind and solar. One approach that researchers and developers are taking to reduce the cost of wave energy is...
Collective migration in animal groups is often guided by distributed leader agents that influence their peers by modulating their motion behaviors. Distributed leadership is a promising navigation strategy for artificial swarms, but designing the leaders’ controllers is difficult due to the swarm’s collective emergent behaviors. The presented research formulates a...
Controllers for robotic systems can be complex and difficult to write by hand. Learning offers an approach to improve a controller through direct feedback. Learning is not trivial, as the feedback does not tell the agent how to improve, only how well its current actions solve the given task. Learning...
Mystical experiences are ineffable, thus defining mysticism itself is a difficult feat. To aid in the construction of a definition of mysticism it is imperative to break down the unique elements of a mystical experience and try to give examples of where we can see all of these elements interacting....
Among the suite of water resources management strategies, water banking can be a tool for water resource management in areas with high water demands or localized water scarcity. This research aims to further the understanding of water banking by conducting a review and analysis of relevant state legislation. This research...
Deep neural networks currently comprise the backbone of many applications where safety is a critical concern, for example: autonomous driving and medical diagnostics. Unfortunately these systems currently fail to detect out-of-distribution (OOD) inputs and can be prone to making dangerous errors when exposed to them. In addition, these same systems...
The ability to extract uncertainties from predictions is crucial for the adoption of deep learning systems to safety-critical applications. Uncertainty estimates can be used as a failure signal, which is necessary for automating complex tasks where safety is a concern. Furthermore, current deep learning systems do not provide uncertainty estimates,...
Reef fish traded alive for table food is a high value-to-volume fishery, with demand centred in luxury markets in Hong Kong and southern mainland China. Approximately twenty countries in the Asia-Pacific region supply these markets. A number of economic, environmental and social issues have arisen from the trade; including the...
The Oregon Coast's small water systems, like the vast number of small water systems across the U.S., are greatly vulnerable. Failing infrastructure, limited financial capital, and inadequate staff combined with future changes in climate, population size, and regulatory stringency spell out a potentially dire future for the region's water supply...
Meditation research in recent decades has disproportionately focused on the Buddhist derived practice of “mindfulness” meditation while leaving most other Buddhist meditation practices unstudied. The current study seeks to remedy this homogeneity through the adaptation of a novel meditation practice used in Tibetan Buddhism to affect motivation. We explored traditional...
Unmanned Aerial System (UAS) technology is a rapidly developing technological marketspace. This thesis focuses on micro, tethered, coaxial UASs and the development of an electrically-tethered observation platform (ETOP). The thesis details the current status of the technology as well as current products on the market. Stability considerations, critical when adding...
Influenza A and Respiratory Syncytial Virus (RSV) are both enveloped, negative strand
RNA viruses which infect the respiratory mucosa of animals and humans. Despite
decades of research and development of antivirals and vaccines, both of these viruses
continue to be a major health concern throughout the world. The focus of...
Structured estuarine habitats, such as salt marshes, seagrass beds, and oyster reefs, are recognized as critical nurseries for juvenile fish and crustaceans. Estuarine habitat usage by fish, including juvenile Pacific salmon Oncorhynchus spp., was characterized by sampling with a modified tow net in Willapa Bay, Washington, where 20% of the...
Multiagent approaches are well suited to designing autonomous solutions for systems that feature complex interactions between many individuals such as in autonomous traffic systems and multi-robot exploration systems. However, creating autonomous agents that function effectively in these systems is a challenging task. In these complex environments, agents need informative reward...
Multi-robot teams offer promising solutions for many long term deployments in remote and dangerous domains, such as extraterrestrial or underseas exploration. However, long term deployments present many problems preventing robot teams from operating effectively. Learning over long time scales is makes it difficult to assign credit to robots' actions, as...
Autonomous agents that sense, decide, act, and coordinate effectively with each other are critical in many real-world domains such as autonomous driving, search and rescue missions, air traffic management, and underwater or deep space exploration. All such domains share a key difficulty: though high-level mission goals are clear to system...
In this thesis, we introduce alignment-based algorithms for improving the performance of reinforcement learning solutions for problems where the reward signal cannot be collapsed into a single number. Many real world problems require an agent to balance performance, longevity, and safety, and do so across different timelines. The key to...
A wave-by-wave forecasting system is desired for optimization of wave energy conversion devices and for improving safety of vessel-based marine operations. This study outlines the first validation attempts of a recently developed forecasting system called Wavecast. The forecasting approach uses X-Band marine radar images for data assimilation, then reconstructs and...
In recent years there have been many improvements in the reliability of critical infrastructure systems. Despite these improvements and despite targeted efforts to improve the operation and control of the electric grid, the power systems industry has seen relatively small advances in this regard. For instance, today's power system is...
Design and control of legged robots is a popular field in the pursuit of building robots that can be as mobile as humans. While much effort is put into understanding how to control the dynamics of these legs, less effort is focused on designing and controlling robot ankles. Ankles on...
Bridge inspections are vital for monitoring the health and serviceability of transportation infrastructure throughout the world. However, inspections can be logistically-challenging, expensive, and dangerous. For example, inspections may require climbing, as well as the use of scaffolding, ladders, rescue boats, bucket trucks, and/or under-bridge inspection vehicles. Small, multirotor unmanned aircraft...
Traditional robots have a long history in nuclear-related work because their integration decreases risk to humans in dangerous environments. Soft robotics is one promising new branch of traditional robotics with proposed applications in industry, medicine, and society. Collaborators from the Robotics mLab at Oregon State University (OSU) are currently working...
Creative nonfiction is a genre replete with contradictions--the name itself shows that: nonfiction writing is true and factual, but creative writing is imaginative and inventive. Because of fundamental contradictions like this, there is no standardized or even most common definition of the genre. This creates confusion for both critics and...
Oregon has already experienced the impacts of climate change, and these impacts are expected to become increasingly severe and varied. In response, the State of Oregon has taken a number of actions to adapt to changing conditions, including coordinated planning approaches to climate change adaptation. However, climate change adaptation actions...
Bipedal locomotion is a complex phenomenon to understand and control, making it difficult for legged robots to achieve the speed, agility, efficiency, and robustness of their animal counterparts. This thesis argues for the use of numerical optimization to investigate and implement bipedal control as it applies to biology, dynamical models,...
Impact of reproductive processes upon female health has yielded conflicting results; particularly in relation to the role of
reproduction-associated stress. We used the viviparous tsetse fly to determine if lactation, birth and involution lead to
damage from oxidative stress (OS) that impairs subsequent reproductive cycles. Tsetse females carry an intrauterine...
The defect mechanisms that underpin the high energy density dielectric 0.8BaTiO₃–0.2Bi(Zn₁/₂Ti₁/₂) O₃
were investigated. Characterization of the nominally stoichiometric composition revealed the
presence of a Ti³⁺-related defect center, which is correlated with lower resistivities and an
electrically heterogeneous microstructure. In compositions with 2 mol. % Ba-deficiency, a barium
vacancy-oxygen vacancy...
Full Text:
. DeRose,2 Geoffrey L. Brennecka,3 and David P. Cann1
1Materials Science, School of Mechanical, Industrial
The defect mechanisms that underpin the high energy density dielectric 0.8BaTiO₃–0.2Bi(Zn₁/₂Ti₁/₂) O₃
were investigated. Characterization of the nominally stoichiometric composition revealed the
presence of a Ti³⁺-related defect center, which is correlated with lower resistivities and an
electrically heterogeneous microstructure. In compositions with 2 mol. % Ba-deficiency, a barium
vacancy-oxygen vacancy...
Full Text:
ceramics
Natthaphon Raengthon,1 Victoria J. DeRose,2 Geoffrey L. Brennecka,3 and David P. Cann1
1Materials
The defect mechanisms that underpin the high energy density dielectric 0.8BaTiO₃–0.2Bi(Zn₁/₂Ti₁/₂) O₃ were investigated. Characterization of the nominally stoichiometric composition revealed the presence of a Ti³⁺-related defect center, which is correlated with lower resistivities and an electrically heterogeneous microstructure. In compositions with 2 mol. % Ba-deficiency, a barium vacancy-oxygen vacancy...
Whole ecosystem carbon dioxide (CO₂) exchange estimated with the eddy covariance (EC) technique has been central to studies on the responses of terrestrial ecosystems to disturbance and intra‐annual and interannual variations in climate, but challenges exist in understanding and reducing the uncertainty in estimates of net ecosystem exchange (NEE) of...
We present a new estimate for the crustal phosphorous sink that results from reactions among seawater, basalt, and sediment blanketing low temperature mid-ocean ridge flank hydrothermal systems. New estimates for global hydrothermal power output, sediment thickness, and the dissolved phosphate concentrations in basement formation fluids indicate that fluid flow through...
