Superconducting gravity gradiometer mission. Volume 1: Study team executive summary

An executive summary is presented based upon the scientific and engineering studies and developments performed or directed by a Study Team composed of various Federal and University activities involved with the development of a three-axis Superconducting Gravity Gradiometer integrated with a six-axis superconducting accelerometer. This instrument is being developed for a future orbital mission to make precise global gravity measurements. The scientific justification and requirements for such a mission are discussed. This includes geophysics, the primary mission objective, as well as secondary objectives, such as navigation and tests of fundamental laws of physics, i.e., a null test of the inverse square law of gravitation and tests of general relativity. The instrument design and status along with mission analysis, engineering assessments, and preliminary spacecraft concepts are discussed. In addition, critical spacecraft systems and required technology advancements are examined. The mission requirements and an engineering assessment of a precursor flight test of the instrument are discussed

Numerical simulations and experimental results of the deployment of thin-walled bistable composite booms

For advanced space missions, meeting the concurrent requirements of increasing payload size while minimizing spacecraft volume can be achieved through the utilization of deployable structures. In a previous study, we conducted a characterization of a thin/walled boom in terms of its interaction between attitude and elastic dynamics when fully deployed. In this current work, we have developed a numerical model to analyze the critical phase of the deployment process. We compared the model's predictions with theoretical expectations and experimental data, and found a strong agreement between them. Additionally, we investigated the effects of bistability on the deployment process by conducting experiments on both a bistable and a monostable boom. Lastly, we performed deployment tests on a free-floating platform, which emulates a small satellite, to quantitatively measure the attitude perturbations caused by the rapid deployment of the boom

TECHNICAL EVALUATION OF FLOATING OFFSHORE WIND PLANTS AND INSTALLATION OPERATIONS

Offshore wind energy is witnessing remarkable growth, driven by the global shift towards sustainable and renewable energy sources. A pivotal innovation in this domain is floating offshore wind technology, which represents a transformative opportunity in harnessing wind energy from deep waters, where conventional fixed-bottom offshore wind systems face limitations due to depth constraints and escalating costs. In light of regional commitments to lower carbon emissions in energy generation, the accessibility of deep-water zones, rich in offshore wind resources, becomes increasingly critical. Despite the promising prospects, the floating offshore wind turbine (FOWT) developments present intricate challenges encompassing design, installation, and operational logistics. This study adopts a two-pronged approach, beginning with a technical review of the current state-of-the-art FOWT technology, drawing from a wide range of literature, industry reports, and guidelines. Building upon this foundation, the research introduces a simulation tool tailored for floating offshore wind deployment operations, designed to analyze and navigate the various phases of FOWT construction. The tool pre-simulates planned installations, factoring in design specifications, weather conditions, and unique location attributes. The simulation aids in task scheduling, long-term installation potential projections, and determining project pacing needs, thereby informing future FOWT and infrastructure developments. The analysis delves into the nuanced interplay of FOWT design, scale, and environmental variables, highlighting the impact of location-specific metocean patterns on bottleneck installation tasks. The resulting vii analysis provides strategic insights for enhancing FOWT technology, emphasizing innovation and standardization in addressing dynamic installation challenges. This thesis aims to increase the commercial viability and contribute to advancing FOWT projects

On the Kite-Platform Interactions in Offshore Airborne Wind Energy Systems: Frequency Analysis and Control Approach

This study investigates deep offshore, pumping Airborne Wind Energy systems, focusing on the kite-platform interaction. The considered system includes a 360 m2 soft-wing kite, connected by a tether to a winch installed on a 10-meter-deep spar with four mooring lines. Wind power is converted into electricity with a feedback controlled periodic trajectory of the kite and corresponding reeling motion of the tether. An analysis of the mutual influence between the platform and the kite dynamics, with different wave regimes, reveals a rather small sensitivity of the flight pattern to the platform oscillations; on the other hand, the frequency of tether force oscillations can be close to the platform resonance peaks, resulting in possible increased fatigue loads and damage of the floating and submerged components. A control design procedure is then proposed to avoid this problem, acting on the kite path planner. Simulation results confirm the effectiveness of the approach

Energy Harvesters and Self-powered Sensors for Smart Electronics

This book is a printed edition of the Special Issue “Energy Harvesters and Self-Powered Sensors for Smart Electronics” that was published in Micromachines, which showcases the rapid development of various energy harvesting technologies and novel devices. In the current 5G and Internet of Things (IoT) era, energy demand for numerous and widely distributed IoT nodes has greatly driven the innovation of various energy harvesting technologies, providing key functionalities as energy harvesters (i.e., sustainable power supplies) and/or self-powered sensors for diverse IoT systems. Accordingly, this book includes one editorial and nine research articles to explore different aspects of energy harvesting technologies such as electromagnetic energy harvesters, piezoelectric energy harvesters, and hybrid energy harvesters. The mechanism design, structural optimization, performance improvement, and a wide range of energy harvesting and self-powered monitoring applications have been involved. This book can serve as a guidance for researchers and students who would like to know more about the device design, optimization, and applications of different energy harvesting technologies

Middeck Active Control Experiment (MACE), phase A

A rationale to determine which structural experiments are sufficient to verify the design of structures employing Controlled Structures Technology was derived. A survey of proposed NASA missions was undertaken to identify candidate test articles for use in the Middeck Active Control Experiment (MACE). The survey revealed that potential test articles could be classified into one of three roles: development, demonstration, and qualification, depending on the maturity of the technology and the mission the structure must fulfill. A set of criteria was derived that allowed determination of which role a potential test article must fulfill. A review of the capabilities and limitations of the STS middeck was conducted. A reference design for the MACE test article was presented. Computing requirements for running typical closed-loop controllers was determined, and various computer configurations were studied. The various components required to manufacture the structure were identified. A management plan was established for the remainder of the program experiment development, flight and ground systems development, and integration to the carrier. Procedures for configuration control, fiscal control, and safety, reliabilty, and quality assurance were developed

Hydrodynamic performance optimization of semi-submersible floaters for offshore wind turbines

Floating structures have become viable alternatives for supporting wind turbines as offshore wind projects move deeper into the water. The wind is prevalent in deep water (depths > 60 m) all around the world. Because of the amount of potential at these depths, wind turbines will require the design of a floating platform, as current wind turbines are usually fixed at the bottom and rely on ordinary concrete with a gravity base, which is not practical at these depths. Floating offshore wind offers a huge potential for green energy production offshore and the overall energy transition to zero carbon emission in general. With the development of even larger wind turbines in the range beyond 15 MW, the floating concepts become more attractive and competitive from a cost perspective. However, larger turbines and cost optimization also require a re-thinking of established solutions and concepts. New ideas and innovations are required to optimize floating offshore wind farms further. An approach for the optimization of semi-submersible floaters using different surrogate models has been developed in this thesis. A semi-submersible floater is selected and designed to support a 15-MW wind turbine in the North Sea. The optimization framework consists of automatic modeling and numerical simulations in open-source tools as well as obtaining the Pareto fronts using surrogate models and the Genetic Algorithm in CEASES software. A Python-SALOME-NEMOH interface is used to obtain the hydrodynamic properties for geometries defined by various variables. The geometries are subjected to three performance constraints: the static platform pitch, metacentric height, nacelle acceleration, and wind. Loads in operating and parked conditions are considered. Finally, the geometries are optimized using two objective functions related to material cost and nacelle acceleration, and the results are discussed. This work contributes to developing efficient design optimization methods for floating structures

Ion engine thrust vector study Final report

Thrust vector misalignment in ion engin

Superconducting gravity gradiometer mission. Volume 2: Study team technical report

Scientific and engineering studies and developments performed or directed by a Study Team composed of various Federal and University activities involved with the development of a three-axis superconducting gravity gradiometer integrated with a six-axis superconducting accelerometer are examined. This instrument is being developed for a future orbital mission to make precise global gravity measurements. The scientific justification and requirements for such a mission are discussed. This includes geophysics, the primary mission objective, as well as secondary objective, such as navigation and feats of fundamental laws of physics, i.e., a null test of the inverse square law of gravitation and tests of general relativity. The instrument design and status along with mission analysis, engineering assessments, and preliminary spacecraft concepts are discussed. In addition, critical spacecraft systems and required technology advancements are examined. The mission requirements and an engineering assessment of a precursor flight test of the instrument are discussed

Design and testing of a magnetic suspension and damping system for a space telescope

The basic equations of motion are derived for a two dimensional, three degree of freedom simulation of a space telescope coupled to a spacecraft by means of a magnetic suspension and isolation system. The system consists of paramagnetic or ferromagnetic discs confined to the magnetic field between two Helmholtz coils. Damping is introduced by varying the magnetic field in proportion to a velocity signal derived from the telescope. The equations of motion are nonlinear, similar in behavior to the one-dimensional Van der Pol equation. The computer simulation was verified by testing a 264-kilogram air bearing platform which simulates the telescope in a frictionless environment. The simulation demonstrated effective isolation capabilities for disturbance frequencies above resonance. Damping in the system improved the response near resonance and prevented the build-up of large oscillatory amplitudes