Ocean Power Technologies (United States)

Abstract The experimental validation of algorithms depends strongly on the characteristics of the test set used. Ideally, such a set should exhibit diverse characteristics that challenge an algorithm and are present in real-world problems. An approach to examine the diversity and representativeness of a test set is Instance Space Analysis, which uses a 2D projection to visualise the test set while identifying the strengths and weaknesses of competing algorithms. However, this has the limitation of discarding potentially useful information while crowding out the space as more features and algorithms are considered. This paper describes an extension of Instance Space Analysis into 3D, which retains a higher degree of information while maintaining the explainability of the visualisation by finding the rotations that maximise the linear trends. In addition to the expansion to 3D, a new algorithm for identifying portfolio footprints is introduced, offering a more robust and reliable method for identifying footprints in both 2D and 3D instance spaces. As a case study, we present a performance analysis of unsupervised anomaly detection methods, subject to changes in the normalisation technique. The results demonstrate the advantages by identifying regions of strength of algorithms previously thought to be underpowered.

In this study, we diagnose the spatial variability in the energetics of tidally generated diurnal, semidiurnal, and supertidal internal wave vertical modes (up to mode 6) in a 30-day forward global ocean model simulation with a 4-km grid spacing and 41 layers. This simulation is forced with realistic tides and atmospheric fields. While diurnal modes are mostly generated in the western Pacific, semidiurnal modes are more ubiquitous in the global ocean. Supertidal modes are mostly generated at low latitudes. For all frequency bands, most of the energy is in mode 1. Diurnal modes are fully resolved beyond mode 6, semidiurnal modes are fully resolved up to mode 4, and supertidal modes are fully resolved up to mode 2, in agreement with a canonical horizontal resolution criterion. The meridional trends in the kinetic to available potential energy ratios of these resolved modes agree with an internal wave consistency relation. The supertidal band is dominated by the higher harmonics of the diurnal and semdiurnal tides, of which the terdiurnal and quarterdiurnal mode-1 waves have the most energy. Terdiurnal modes are mostly generated in the west Pacific, where diurnal internal tides are strong. In contrast, quarterdiurnal modes occur at all longitudes near strong semidiurnal generation sites. The consistency relation and frequency-wavenumber spectra show that the resolved supertidal modes are dispersive internal waves. These waves are likely generated by near-resonant interactions between tidal modes of the same mode number, which are enhanced in the tropics.

The National Centers for Environmental Prediction (NCEP) produces operational reanalysis products based on the Global Ocean Data Assimilation System (GODAS) with the Modular Ocean Model (MOM3/MOM4p0d) as a physical model and 3D-Var as the data assimilation method. The Indian National Center for Ocean Information Services (INCOIS) also produces operational ocean analysis with the same GODAS with MOM4p0d. In this study, GODAS is upgraded with MOM5. The improved reanalysis is compared with respect to the EN4 and Ocean ReAnalysis System 5 (ORAS5) for the subsurface temperature and salinity. The microwave-based satellite-derived sea surface temperature (SST) is employed for the independent evaluation of the reanalysis SST products. We have assimilated observed temperature and salinity profiles from all in situ platforms over the global ocean and also assimilated along-track sea level anomaly from altimeter (Jason1 and Jason2) to produce the improved reanalysis. There is a significant improvement in the SST with biases of temperatures reduced from 1.5 to ~ 0.2 °C as compared to without assimilation. Moreover, a significant improvement is found in the subsurface temperature and salinity fields over the northwest Atlantic and Pacific Ocean, Nino 3.4, and Indian Ocean thermocline ridge regions. The biases in this new, improved reanalysis are even lower than ORAS5 when compared with EN4 analysis. Thermocline depth also shows improvement in terms of better representation and capturing seasonal variability. Altimeter assimilation further reduces Root Mean Square Deviation (RMSD) in SST over the global ocean. We also show the improvement in the new reanalysis with respect to the reanalysis based on MOM4p0d.

Power electronic devices plays major role in controlling and improving the drive system. because of the robustness, good performance and solidness of an induction motor it is highly recommended for the industrial application. In order to obtain better performance from this kind of motors we use converters to control the motor with input parameters. But when we use the power electronic elements there is high chance of failure of this elements. This failure may lead to short-circuit fault, open-circuit fault and many other which may occur in DC link in converter of drive system. Short-circuit faults in converters will make big differences in every parameter and we have our normal conventional methods to deal with it. But open-circuit faults make system run at low efficiency and these faults are unable to find immediately. Neglecting these kinds of faults may lead to damage the other elements in the system. So, in this paper diagnosis models for the open-circuit faults in inverter fed induction motor using machine learning models and multilayer perceptron classifier is presented. In this model RMS currents and RMS voltages of each phase have been considered as a feature by which models have been trained and also valid simulation test results provided.

Abstract Strongly coupled data assimilation (SCDA), such as using atmospheric observations to update ocean analyses, is critical for properly initializing Earth System models to predict subseasonal to decadal timescales. We show that a Kalman filter with a linear emulator of the coupled dynamics can be used to efficiently assimilate observations with SCDA. A linear inverse model (LIM), trained on 25 years of Climate Forecast System Reanalysis gridded data, is used to assimilate observations daily during an independent 7‐year period. SCDA sea‐surface temperature (SST) analysis errors are reduced over 20% in global‐mean mean‐squared error relative to a control experiment where only SST observations are assimilated with an SST LIM. The analysis improvements enhance forecast skill for leads of at least 50 days. In contrast, extratropical Northern Hemisphere 2 m air temperature forecast errors increase for coupled data assimilation in these experiments, despite reduction during the training period.

Abstract Due to rig availability and costs, operators can face significant delays in well decommissioning before plug and abandonment (P&A), during which temperature and pressure monitoring is required. If an umbilical connected to these wells fails, then it must be replaced, adding additional costs to a field with nonproducing wells. This study addresses a solution to replacing a faulty umbilical in a small field where hydraulics are already supplied to the wells, but power and communications are failing. Ocean Power Technologies, Inc. (OPT) has developed the PB3 PowerBuoy® that converts wave energy into local electric power. The PB3 can provide power and communications for many applications, including subsea well monitoring. OPT partnered with a prominent North Sea-based subsea controls original equipment manufacturer (OEM) and engineering company to perform a preliminary front-end engineering and design study to evaluate the use of a PB3 PowerBuoy to provide power and communications for two subsea trees (XTs) located in the North Sea. The Subsea Control Modules (SCMs) for these two XTs are powered by an umbilical from a production platform, providing power, communications, and hydraulics. Given the government regulations for well monitoring until P&A, having a plan for an independent backup power source is critical. In this study, the PB3, umbilical cable, and OPT's subsea battery module (SSB) are added to the existing subsea infrastructure to provide power to the subsea XTs and relay data back to the production platform via a Tampnet 4G node on the PB3. These requirements have been compared with the PB3's expected power generation capabilities in this location to develop a preliminary system configuration. As a part of this study, OPT has also completed a preliminary mooring and umbilical cable analysis. In addition, OPT worked with our partners to develop a preliminary communications plan to integrate their legacy frequency shift keying (FSK) communications into the PB3 network by use of a modified downhole interface unit (DIU) containing a terminal server to network the master control station (MCS) on the production platform to the SCMs. This study shows that OPT's PB3 can provide power and communications to subsea wells requiring monitoring through renewable wave-powered energy. Such a development will provide proof-of-concept for using the PB3 as a remote power and well control solution on future all-electric developments.

Abstract The inner shelf, the transition zone between the surfzone and the midshelf, is a dynamically complex region with the evolution of circulation and stratification driven by multiple physical processes. Cross-shelf exchange through the inner shelf has important implications for coastal water quality, ecological connectivity, and lateral movement of sediment and heat. The Inner-Shelf Dynamics Experiment (ISDE) was an intensive, coordinated, multi-institution field experiment from September–October 2017, conducted from the midshelf, through the inner shelf, and into the surfzone near Point Sal, California. Satellite, airborne, shore- and ship-based remote sensing, in-water moorings and ship-based sampling, and numerical ocean circulation models forced by winds, waves, and tides were used to investigate the dynamics governing the circulation and transport in the inner shelf and the role of coastline variability on regional circulation dynamics. Here, the following physical processes are highlighted: internal wave dynamics from the midshelf to the inner shelf; flow separation and eddy shedding off Point Sal; offshore ejection of surfzone waters from rip currents; and wind-driven subtidal circulation dynamics. The extensive dataset from ISDE allows for unprecedented investigations into the role of physical processes in creating spatial heterogeneity, and nonlinear interactions between various inner-shelf physical processes. Overall, the highly spatially and temporally resolved oceanographic measurements and numerical simulations of ISDE provide a central framework for studies exploring this complex and fascinating region of the ocean.

To determine the absorption, distribution, metabolism and excretion of abivertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor, in patients with advanced non-small cell lung cancer (NSCLC). Seven patients with advanced NSCLC were given a single 200 mg/83 μCi oral suspension of [14 C]-abivertinib. Blood, urine and faeces were collected. Mass balance of radioactivity, the pharmacokinetics of abivertinib, and the total radioactivity were determined. Metabolite profiling and characterisation were performed. The mean recovery was 82.16%, with 2.38 and 79.78% of the radioactive dose excreted in urine and faeces, respectively. The unchanged abivertinib was the major radioactive component detected in plasma within the first 24 hours after dosing, accounting for 59.17% of the total drug-related radioactivity. Abivertinib in urine accounted for only 0.96% of the administered dose, whereas in faeces it accounted for 33.36%. Eight metabolites were detected and characterised in plasma, among which MII-7, a product of cysteine glycine conjugate, was the only circulating metabolite, accounting for approximate 10.6% of the total drug-related exposure. MII-2 (an abivertinib cysteine-glycine adduct) and M7 (a reduced product of abivertinib) were the 2 major metabolites in the excreta, accounting for 20.0 and 12.4%, respectively, of the drug-related radioactivity in faeces. Following a single oral administration, the unchanged abivertinib was the predominant drug-related material in plasma, urine and faeces. The drug-related materials were primarily eliminated via the faecal route. Direct glutathione conjugation of abivertinib played a significant role in the metabolic clearance and metabolite exposure of abivertinib.

A 2-layer non-hydrostatic model with improved dispersive behaviour is presented. Due to the assumption of a constant non-hydrostatic pressure distribution in the lower layer, the dispersive behaviour is improved without much additional computational time. A comparison with linear wave theory showed that this 2-layer model gives a better result for the dispersion relation and shoaling of waves in intermediate water. This means that the 2-layer model is applicable in shallow and intermediate water depths (up to relative depths kh equals 4), whereas the 1-layer model is only applicable in shallow water depths (kh smaller than 1). Three laboratory experiments, including a fringing reef and a barred beach, were used to validate the presented mode for different hydrodynamic conditions. Based on these results, it can be concluded that the 2-layer model can be applied to accurately simulate the bulk wave height and spectral properties. The low frequency wave height, the setup and in particular the second order statistics contain more scatter, but the model accurately captured the general trend. Furthermore, the model showed good results for complex bathymetries in shallow to intermediate water.

Abstract New innovative services and goods based on artificial intelligence, next-generation robotics, autonomy, digitization, and electrification are taking root in the ocean economy. More typical competitive forces, such as value enhancement and safety improvement, are also present, as suppliers constantly strive to improve their competitive positioning. Concurrently, the Oil and Gas sector is experiencing mounting pressure to decrease its operational carbon emissions, forcing efforts to reduce or eliminate liquid fuel consumption offshore. Companies in the ocean economy are having to react to this combination of macro- and micro-level drivers and innovate at an ever more rapid pace. However, before many of these new capabilities can be implemented, new, clean, reliable power sources are needed, especially as liquid fuel grows increasingly out of favor. For many of these loads—both old and new and ranging from watts to megawatts—wave energy systems provide the best solution for remote power generation. As such, research, development and demonstration activities are underway to prove wave energy's ability to provide reliable, consistent energy supplies for certain offshore Oil and Gas activities, paving the way for near term commercialization. This paper outlines these drivers, competitive reaction to them, and why and how wave energy can be a preferable choice for power at sea.