In eastern boundary current upwelling ecosystems, mesoscale circulation features such as eddies and upwelling filaments play a prominent role in the transfer of water and the associated plankton from the productive nearshore to the oligotrophic deep sea. The relationship between mesoscale circulation, zooplankton distributions, and the across-shelf transport of coastal...
We used wavelet analyses of sea surface height (SSH) from >13 years of satellite
altimeter data to characterize the variability in mesoscale circulation in the northern
California Current (35°N–49°N) and explore the mechanisms of variability. We defined
‘‘mesoscale’’ circulation as features, such as eddies and filaments, which have 50- to...
Unusual collections of several euphausiid, chaetognath, and copepod species help elucidate
the effects of the strong 1997/1998 El Niño off the central Oregon, USA, coast. Furcilia of Nyctiphanes simplex, a euphausiid typically found only as far north as central California, were collected in bi-weekly nearshore samples between December 1997 and...
New low enriched uranium (LEU) fuels are being developed for replacement of high enriched uranium (HEU) fuels in high power research reactors. U-Mo LEU plate fuels have been identified as a candidate for replacement of current HEU fuels. However, U-Mo fuels tend to exhibit accelerated swelling typically at fission densities...
A pair of hydrographic sections, one north and one south of Cape Blanco at 42.9N, was sampled in five summers (1998–2000 and 2002–2003). The NH line at 44.6N lies about 130 km south of the Columbia River, and spans a relatively wide shelf off Newport, Oregon. The CR line at...
The thermal degradation of structural materials is considered to be a key factor for evaluating the lifetime of current nuclear power plants. Ni-based and Fe-based alloys, such as 690, 625, 304, and 316, are widely used in nuclear industry as structural components due to the extraordinary corrosion resistance and mechanical...
The corrosion behaviors of carbon and stainless steels were investigated in supercritical CO₂ (sCO₂ ) containing H₂O and O₂ simulating conditions that exist in direct sCO₂ power cycle heat exchangers. Thermodynamic properties of CO₂-H₂O-O₂ systems related to the corrosion phenomena were determined using NIST software. The exposure tests of the...
Using supercritical CO₂ (sCO₂) as a working fluid has increasingly gained attention in the energy industry. sCO₂ power cycles has various advantages, such as high cycle efficiency, compact turbomachinery, and potential zero CO₂ emission. Along with these benefits, materials degradation issues have also been emphasized in the last decade. Aqueous...
Mechanical property degradation due to isothermal ageing is of potential concern for alloys based on the Ni-Cr binary system (e.g., Inconel 690, 625), particularly in nuclear power applications where component lifetimes can exceed 40 years. In the present research, the disorder-order phase transformation, which is the primary mechanism of ageing,...
The corrosion resistances of several alloys were investigated to optimize performance and cost in seawater and supercritical CO2 environments. Many alloys are prone to corrosion in seawater and/or supercritical CO2 containing impurity environments. Exposure and electrochemical experiments were conducted in both environments to evaluate alloys’ corrosion resistance. In seawater corrosion...
Glioblastoma is a malignant brain tumor that has extremely poor prognoses with a 5 year survival rate of less than 5%. The low survival rates of glioblastoma patients is attributed to glioblastoma cells being extremely resistant to radiotherapy and chemotherapy as well as being very invasive. We previously identified calpain...
This work explores the hypothesis that proton irradiation is a feasible alternative to simulate accelerated thermal aging for Ni2Cr long-range ordered phase formation within NiCr and NiCrFe alloys. In this study, various model alloys and commercial alloys 690 and 690+P (0.01 wt.% P) were subject to 2 MeV proton irradiation...
The goal of the Pacific Ocean Boundary Ecosystem and Climate Study
(POBEX) was to diagnose the large-scale climate controls on regional transport
dynamics and lower trophic marine ecosystem variability in Pacific Ocean boundary
systems. An international team of collaborators shared observational and eddy-resolving
modeling data sets collected in the Northeast...
Seeding is a vital tool to facilitate recovery of degraded ecosystems, but low seedling recruitment rates limit the utility of this practice in a range of ecosystems across the globe. Plant functional traits impact individual fitness through effects on growth, reproduction and survival. Consequently, seed and seedling trait variation among...
In 1987, Congress authorized a 5 year $150 million dollar research program called
the Strategic Highway Research Program (SHRP). SHRP was divided into four major
areas, including the asphalt research program. The asphalt research program was divided
into six major research contracts, one such contract, SHRP-003A was called Performance
Related...
Acculturation, defined as the process of adopting the behaviors and beliefs of the dominant host culture, is often associated with dietary change and negative health outcomes, such as increased risk for obesity and diet-related diseases. The large and rising immigrant population in the U.S. necessitates a better understanding of the...
The use of the triaxial test to characterize the strength of soils for civil engineering applications is widespread. These tests are typically conducted with confining stresses in excess of 5 psi. To characterize the
strength of a soil located in the upper layers of the subgrade of an aggregate
surfaced...
An effort was made to determine what factors are responsible for differences in color quality between preserves commercially manufactured from Hood and Tioga strawberry varieties. Color analyses made on Hood and Tioga preserves, during a 26 week storage period, included spectral measurements of aqueous extracts from the preserve samples. In...
The purpose of this study was to analyze and compare the women's festival costumes of the two areas surrounding Skopje, Jugoslavia. It was also intended to preserve pertinent information for these costumes, which are disappearing. A trip was made to Macedonia, and villages were visited in search of old, traditional...
The Beat Generation was an American counter-culture movement in the 1950's. Comprised of nomadic writers, poets, actors, musicians, and artists, the Beat movement represented no systematic philosophy and its most distinguishing characteristic was its apolitical disengagement from society. The Beats offered no substantive alternatives to the existing social order, but...
Mycobacterium avium cause disseminated disease in immunocompromised people such as AIDS patients. Subsequent to crossing the intestinal epithelium, M. avium thrive within vacuoles in macrophages. The bacteria exhibit a different, more invasive, phenotype after being in macrophages compared to M. avium from laboratory conditions. We hypothesized that this intracellular phenotype...
The influence of vesicular-arbuscular mycorrhizae (VAM) on
populations of general taxonomic and functional groups of naturally-occurring
rhizosphere bacteria and actinomycetes associated with
roots of sweet corn (Zea mays var. rugosa) and subterranean clover
(Trifolium subterraneum L.) was assayed using selective media.
Sporangial production by Phytophthora cinnamomi was also used as...
Artificial collectives are useful for accomplishing tasks that require teamwork from multiple simple robots. Multiple robot and collective testbeds have been developed, yet none stay committed to leverage the local interactions, group size, and imperfect information assumptions that strengthen biological collectives. A review of the collective and multiple robot literature,...
This study examines dissolved rhenium (Re) as a function of water runoff using river samples from two contrasting watersheds, the Eel and Umpqua Rivers in the Pacific Northwest, USA. These watersheds share many key characteristics in terms of size, discharge, climate, and vegetation, but they have a 10-fold difference in...
The corrosion resistance of steels and nickel based alloys was investigated in supercritical CO2 (sCO2). Two types of experiments were conducted. The first set of experiments were conducted in a low temperature aqueous environment to simulate conditions that would exist in direct sCO2 power cycle low temperature heat exchangers. The...
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...
This dissertation works towards determining the mechanisms driving the Mo isotopic composition of soils, and how these signals may be used to refine the use of Mo as a proxy of biogeochemical processes. The first step towards quantifying Mo fractionation in soils is to determine the mechanisms controlling Mo accumulation,...
Dust deposition on ecosystems with highly weathered soils may provide vital rock-derived nutrients that maintain ecosystem productivity. Because of the difficulties in measuring temporally and spatially heterogeneous dust deposition over ecologically meaningful timescales, evaluations of the spatial variability in dust deposition are extremely rare. In the Luquillo Mountains of Puerto...
Directed energy deposition and laser cladding technologies are suitable advanced manufacturing techniques for applying corrosion-resistant claddings to large carbon steel components. In this work, we clad 309L stainless steel wire onto carbon steel substrates and examine the effects of cladding parameters (laser power and travel speed) on metallurgical bonding, composition,...
High purity niobium metal is used in the construction of superconducting radio frequency (SRF) cavities in superconducting particle accelerators, such as the Large Hadron Collider (LHC) at CERN or the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. The usual method for characterizing the impurities in this niobium, the...
Disaster response and surveillance operations will increasingly incorporate Unmanned Aerial Vehicles (UAV)s due to their cost-effectiveness and maneuverability. This trend has driven the research on small-sized quadcopters for varying indoor applications. Small-sized quadcopters' payload and computational capacity limit the usage of complex vision-based collision avoidance algorithms that are employed by...
Duplex stainless steels (DSS) are an attractive potential material in nuclear power generation systems due to an excellent combination of corrosion resistance, strength, toughness, and affordability. Thermal embrittlement caused by phase instability in the temperature range of ~300-550°C severely limits the service temperature of DSS. The rate of embrittlement varies...
Demanding task environments (e.g., supervising a remotely piloted aircraft) require performing tasks quickly and accurately; however, periods of low and high operator workload can decrease task performance. Intelligent modulation of the system’s demands and interaction modality in response to changes in operator workload state may increase performance by avoiding undesirable...
This work explores the mechanical properties of single-phase niobium alloy C103 from room temperature to 600°C for the purpose of expanding safe uses of the material into new applications. The study utilizes a symmetrically notched triaxial tensile specimens to manipulate the internal stress field in order to observe the changes...
Human-robot teams involve humans and robots collaborating to achieve tasks under various environmental conditions. Successful teaming requires robots to adapt autonomously in real-time to a human teammate's state. An important element of such adaptation is the ability for the robot to infer the tasks performed by their human teammates. Human-robot...
Variations in heat treatments have significant effects on the microstructure of tool steels. For CPM-M4 tool steel, the changes in microstructure and mechanical properties were observed based off of variations in temperature. Five heat treatments with constant exposure time and variable austenitizing and tempering temperatures were performed on samples of...
Nickel (Ni)-based alloys with a high chromium (Cr) content are frequently employed in applications where elevated temperatures and/or corrosive environments are present due to their excellent corrosion resistance and mechanical properties. However, a gap exists around the formation, and kinetics of long-range order (LRO) Ni2Cr phase in both model binary...
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...
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...
The advent of supercritical CO2 as a new heat-exchange medium has seen strong interest from the power industry and the energy research field recently. It is advan- tageous in comparison with other heat-exchange cycles, as it can be operated safely at much higher temperatures and pressures, thus increasing the thermal...
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);...
Seasonal emergent wetlands in the Pacific Northwest have not been regarded traditionally as fish rearing habitat, despite access to such habitat when river flows overtop riverbanks and connect to the floodplain. As a result, restoration and enhancement projects to remediate for the loss of such wetland habitat are being implemented...
In this paper, we derive the fundamental solution to the heat equation with a discontinuous diffusion coefficient in the free space, with an absorbing boundary, and with a reflecting boundary. We use the fundamental solution with an absorbing boundary to make connections with the transition probability density of absorbed Skew...
In transboundary water resources policy and management situations, such as the governance of the Columbia River Basin, complex social, ecological, and economic factors seem to be in irreconcilable competition with one another. However, cooperative negotiation provides an outlet for entities and stakeholders to "expand the pie" and develop creative alternatives...