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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Innovative Features of NASA's Celestial Mapping System to Support Exploration in the Lunar South Pole

Introduction: NASA's Celestial Mapping System (CMS) is developed to address the need for 3D tools for planetary science investigations, mission planning, in-situ operations, in a 3D-first design constructed around a unified view of a planetary globe. At present CMS provides many critical functionalities that include 1) Equipment planning and optimized placement on Lunar surface 2) Line of sight (visibility ) analysis 3) Powerful measurement tools based on 3D terrain with realistic 3D models to represent rovers, astronauts and equipment 4) Visualization of de-rived mapping products (e.g. resource maps), and 5) Data engine for hosting new observations that are not available in other contemporary lunar data tools. CMS is built on the foundation of powerful NASA WorldWind globe engines. In near future, users will be able to simultaneously deploy CMS onto multiple hardware configurations and platforms such as Windows, Linux, iOS and Android. The users will also have the flexibility to update to the latest imagery and terrain datasets as they are being acquired (in real time) before and/or during the exploration mission. CMS is also capable of consumption and analysis of data from locally hosted and external sources. It supports Open Geospatial Consorti-um (OGC) data and file standards, with current integrations of datasets from the Astrogeology Science Center of USGS which include global and local data acquired from NASA (LRO, Clementine, Lunar Orbiter) and JAXA (SELENE/Kaguya) with the capability of integrating more datasets. With development experience in both the end-user application and planetary engine side, CMS is also able to adapt to newer Lunar cartography standards as they develop and become recognized by international geospatial panels. Overcoming Polar Distortions: 3D geospatial applications traditionally suffer from significant distortion of imagery at the poles due to following reasons – 1) distortions in the source imagery 2) Incompatible tessellation algorithm on the poles 3) map projections. In the lunar context, with the focus on the South pole, this is not acceptable. The CMS team is researching ways to address polar distortion of imagery with new tessellation algorithms and by reprojecting the data using projections that are more accurate in polar scenarios. Figure1 shows the potential error introduced by different tessellation methods, represented by the red and green circles for Shoemaker crater. There is ~2 Km difference in the placement of the crater. Line of Sight Analysis and Traverse Planning: We have developed a built-in line of sight analysis (LOS) tool in CMS that analyzes the terrain profile and obstructions and provides the visibility of a given terrain for a remote observer. Figure 2 shows the viewshed analysis on the PSR in Nobile region. The PSR was created with help of HORUS generated images. The yellow pin shows the observer location outside the PSR. The yellow area shows the visible part of PSR. The obstructed area with no visibility for the observer is shown in red. This analysis was ex-tended further to set different heights for various observers and then perform the viewshed analysis. Combining the different visibility profiles can help designing improved traverses within the crater.

Geospatial Mapping↗
NASA NTRS2018

Payload Utilization in NASA's Space Launch System

A revitalized National Space Council has directed NASA to return to the moon, with a series of preparatory missions paving the way for eventual human exploration. NASA's new deep space exploration system -- the heavy-lift Space Launch System (SLS), the Orion crew spacecraft and revitalized launch facilities at Kennedy Space Center -- will enable NASA and its commercial and international partners to meet these goals for human deep space exploration. SLS will be the most capable launch vehicle for these efforts, with an initial Block 1 capability of at least 26 metric tons (t) to trans-lunar injection (TLI). A more powerful Block 1B, available in crew and cargo configurations, with have the power to loft more than 37 t to TLI; the ultimate Block 2 variant will lift more than 45 t to TLI. For payload utilization, the Block 1 vehicle will carry 13 6U CubeSats as secondary payloads while the Block 1B crew vehicle will provide as much volume as the space shuttle payload bay in a Universal Stage Adapter (USA). Block 1B cargo vehicles will offer 8.4 m fairings in 19.1 m and 27.4 m lengths, with enough volume to accommodate habitat modules and landers. For missions beyond the Earth-moon system, SLS offers greater characteristic energy (C3), enabling faster transit or heavier payloads to the outer planets. The first mission of SLS and Orion, launching no earlier than December 2019, will send Orion into lunar distant retrograde orbit (DRO) on an approximately 25-day shakedown cruise known as Exploration Mission-1 (EM-1), enabling NASA to verify and validate new systems before sending astronauts to deep space on the next exploration mission. The SLS program and its prime contractors have made significant progress toward first launch, with several major components of the vehicle completed and delivered to the Exploration Ground Systems (EGS) Program at Kennedy Space Center. Major forward work includes integrating tanks, engines and other major sections into the EM-1 core stage at Michoud Assembly Facility and then shipping the entire core stage assembly to Stennis Space Center. There, it will be installed in the refurbished B-2 test stand for a series of integrated stage tests culminating in a green run hotfire test. The Program's Spacecraft Payload Integration and Evolution (SPIE) Office, responsible for the in-space stage, adapters and payload interfaces, has largely completed its effort on the Block 1 vehicle and is supporting manufacture of the first Block 1B vehicle. This paper will provide an overview of the Block 1 vehicle, its expected capabilities, secondary payload accommodations and manufacturing status, including structural testing and the challenges of developing a new launch vehicle. A lookahead to the Block 1B vehicle and the payload utilization opportunities it will provide in the 2020s will also be discussed, including the unique capabilities of the vehicle.

Creech, Stephen D.↗
NASA NTRS1994

Applications of automatic differentiation in computational fluid dynamics

Automatic differentiation (AD) is a powerful computational method that provides for computing exact sensitivity derivatives (SD) from existing computer programs for multidisciplinary design optimization (MDO) or in sensitivity analysis. A pre-compiler AD tool for FORTRAN programs called ADIFOR has been developed. The ADIFOR tool has been easily and quickly applied by NASA Langley researchers to assess the feasibility and computational impact of AD in MDO with several different FORTRAN programs. These include a state-of-the-art three dimensional multigrid Navier-Stokes flow solver for wings or aircraft configurations in transonic turbulent flow. With ADIFOR the user specifies sets of independent and dependent variables with an existing computer code. ADIFOR then traces the dependency path throughout the code, applies the chain rule to formulate derivative expressions, and generates new code to compute the required SD matrix. The resulting codes have been verified to compute exact non-geometric and geometric SD for a variety of cases. in less time than is required to compute the SD matrix using centered divided differences.

Green, Lawrence L.↗
DOE OSTI2025

Plasmon-enhanced ultralow-threshold solid-state triplet fusion upconversion

Triplet fusion upconversion has potential applications in solar cells, photoredox catalysis, additive manufacturing and bioimaging. However, solid-state upconversion systems have struggled to measure up to their solution-phase counterparts, often requiring enormous optical power densities to operate at the maximum efficiency. Here we substantially improve the performance of upconversion films through excitation with surface plasmons that propagate along a planar silver-film interface, leading to an absorption enhancement that reduces the intensity threshold I th by a factor of 19 and enhances the external quantum efficiency by a factor of 17. From this, we achieve I th values as low as 3.4 mW cm −2 and an external quantum efficiency up to 0.094%. To demonstrate real-world viability, we couple the upconversion film to plasmons generated by the near-field of excitons in an organic light-emitting diode. As a result, this scheme is then used to fabricate a white-emitting organic light-emitting diode where blue emission sources from plasmon-excited upconversion, achieving a high colour rendering index of 86.2 and setting precedent for blue emission in the absence of high-energy polarons or triplets.

36 MATERIALS SCIENCE↗
DOE OSTI2023

MiGRIDS

MiGRIDS is a software that models islanded microgrid power systems with different controls and components. For example, using load and resource data from a microgrid, you could model it with additional wind turbines, battery etc. You could also try out different dispatch schemes to see which one worked best. MiGRIDS is designed to help optimize the size and dispatch of grid components in a microgrid. While a grid connect feature is expected to be added in the future, islanded operation is the focus. Note that this is a basic implementation and more features and functionality (such as a GUI) are coming! MiGRIDS runs time-step energy balance simulations for different grid components and controls. In smaller microgrid environments, dispatch decisions are being made on the order of seconds. In order to fully capture their effect, this tool lets you run simulations on the order of seconds. The end result is a more realistic representation of what can be achieved by integrating different components and control strategies in a grid.

Morgan, Tawna↗
NASA NTRS2008

System Engineering for J-2X Development: The Simpler, the Better

The Ares I and Ares V Vehicles will utilize the J-2X rocket engine developed for NASA by the Pratt and Whitney Rocketdyne Company (PWR) as the upper stage engine (USE). The J-2X is an improved higher power version of the original J-2 engine used for Apollo. System Engineering (SE) facilitates direct and open discussions of issues and problems. This simple idea is often overlooked in large, complex engineering development programs. Definition and distribution of requirements from the engine level to the component level is controlled by Allocation Reports which breaks down numerical design objectives (weight, reliability, etc.) into quanta goals for each component area. Linked databases of design and verification requirements help eliminate redundancy and potential mistakes inherent in separated systems. Another tool, the Architecture Design Description (ADD), is used to control J-2X system architecture and effectively communicate configuration changes to those involved in the design process. But the proof of an effective process is in successful program accomplishment. SE is the methodology being used to meet the challenge of completing J-2X engine certification 2 years ahead of any engine program ever developed at PWR. This paper describes the simple, better SE tools and techniques used to achieve this success.

Kelly, William M.↗
NASA NTRS2004

Radio Sounding Techniques for the Galilean Icy Moons and their Jovian Magnetospheric Environment

Radio sounding of the Earth's topside ionosphere and magnetosphere is a proven technique from geospace missions such as the International Satellites for Ionospheric Studies (ISIS) and the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). Application of this technique to Jupiter's icy moons and the surrounding Jovian magnetosphere will provide unique remote sensing observations of the plasma and magnetic field environments and the subsurface conductivities, of Europa, Ganymede, and Callisto. Spatial structures of ionospheric plasma above the surfaces of the moons vary in response to magnetic-field perturbations from (1) magnetospheric plasma flows, (2) ionospheric currents from ionization of sputtered surface material, and (3) induced electric currents in salty subsurface oceans and from the plasma flows and ionospheric currents themselves. Radio sounding from 3 kHz to 10 MHz can provide the global electron densities necessary for the extraction of the oceanic current signals and supplements in-situ plasma and magnetic field measurements. While radio sounding requires high transmitter power for subsurface sounding, little power is needed to probe the electron density and magnetic field intensity near the spacecraft. For subsurface sounding, reflections occur at changes in the dielectric index, e.g., at the interfaces between two different phases of water or between water and soil. Variations in sub-surface conductivity of the icy moons can be investigated by radio sounding in the frequency range from 10 MHz to 50 MHz, allowing the determination of the presence of density and solid-liquid phase boundaries associated with oceans and related structures in overlying ice crusts. The detection of subsurface oceans underneath the icy crusts of the Jovian moons is one of the primary objectives of the Jupiter Icy Moons Orbiter (JIMO) mission. Preliminary modeling results show that return signals are clearly distinguishable be&een an ice crust with a thickness of 7 km on 1) an ocean and 2) a layer of bedrock. Knowledge of the ionospheric contributions to the time delay of the low-frequency subsurface radar is shown to be important in obtaining accurate depth information.

Green, James L.↗
DOE OSTI2020

Challenges in the designing, planning and deployment of hydrogen refueling infrastructure for fuel cell electric vehicles

Hydrogen can power transportation with near zero greenhouse gas emissions. With government support, early market development is now underway in several nations thanks to technological advances in fuel cell vehicles and electricity generation from renewable energy. Deploying a sustainable hydrogen refueling infrastructure faces methodological and practical challenges ranging from the creation of appropriate codes to managing the co-evolution of the refueling network and growth of the stock of hydrogen fuel cell vehicles. Furthermore, this paper presents a comprehensive review of the challenges facing the designing, planning and deployment of hydrogen refueling infrastructure progress to date and outlook for the future. The design and costs of refueling infrastructure as well as the lifecycle environmental effects of hydrogen vehicles depend on how hydrogen is produced and delivered to refueling stations. In recent years, important advances have been made in methods for planning the numbers, sizes and location of hydrogen stations. Institutional barriers are also gradually being overcome. Co-evolving the deployment of stations and the demand for fuel cell vehicles remains a crucial subject for future research.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2023

Splitting photons: Singlet fission in nanocrystal-molecule hybrid structures

The goal of this research is to enable all the energy contained in sunlight to be harvested by making full use of the energy contained in the blue and green wavelengths of light. Current systems are unable to extract all of the energy available from photons in this wavelength range due to rapid relaxation processes that dissipate a fraction of the energy as heat. In this work, inexpensive, earth-abundant components capable of supporting multi-excitonic processes involving more than one tightly bound excited state are investigated as a way to exceed the Shockley-Queisser limit. This research will examine hybrid organic-inorganic nanostructures capable of singlet fission, a process by which one high-energy spin-singlet state is converted into two lower-energy spin-triplet states, and subsequent triplet exciton transfer. Specifically, the organic molecules diphenylhexatriene and tetracene that maximally absorb blue light and are known to exhibit singlet fission will be bound to lead chalcogenide nanocrystals. A variety of steady-state and time-resolved spectroscopic techniques will be used to study the transfer of energy from spin-triplet excitons that are created in the organic molecules to the nanoparticle acceptors. The hybrid nanostructures here will be fully characterized both in solution or thin film via electronic absorption and photoluminescence spectroscopy, nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, transmission electron microscopy, photoelectron spectroscopy, time correlated single photon counting and transient absorption experiments. The effect of molecular and nanocrystal structure on the electronic coupling between the hybrid components will be examined to establish fundamental relationships between structure and triplet energy transfer efficiency. The findings will be directly applicable to a potential tetracene-silicon platform that may ultimately enhance the power conversion efficiency of silicon solar cells.

30 DIRECT ENERGY CONVERSION↗
NASA NTRS2019

Evaluation Studies of a 800W Solid Oxide-Based Fuel Cells Stack for Electrical Power in Aviation

As both NASA and the aeronautics industry recognize the need for higher fuel efficiency and lower carbon emissions in both commercial airline and private aviation applications, development of all-electric or hybrid electric aircraft have garnered renewed interest in the aviation community. For the particular example of the hybrid-electric option, the solid oxide fuel cell (SOFC) is an attractive option for the power source, due to its potential to utilize aviation fuels thereby having minimal impact to aviation infrastructure. SOFC stack performance depends upon many factors, one of the most important is the way the oxidant and fuel gases are delivered to the fuel cells. System modeling of various aircraft configurations for FUELEAP (Fostering Ultra-Efficient, Low-Emitting Aviation Power) point to the need to operate SOFC stacks at high current densities. This creates challenges in the thermal profile of the stacks with potential to create large thermal gradients and hot spots. This study investigates two types of commercial solid oxide fuel cell stacks, the cross flow and co-flow gas designs, both convectively cooled with cathode air. High fuel utilization factors were also employed under varying electrical loads expected from the demands of flight. In addition, performance, range of operation and endurance were investigated under conditions of high current loads and thermal cycling. Evaluations include the study of gas kinetic using electrochemical spectroscopy. Testing took place at the facilities of NASA Glenn using a commercial test system (FuelCon AG, Magdeburg Germany). These studies are crucial to the Glenn Research Center's ability to conduct research, evaluation and development of the next-generation SOFC based stacks for cutting-edge energy technologies for aerospace applications. This study supports NASA's Convergent Aeronautics Solutions' (CAS) FUELEAP project.

Goldsby, Jon C.↗
NASA NTRSDate not supplied

Hydrogen Peroxide-Water-Ethanol Monopropellant Blend for CubeSat Propulsion

Monopropellant propulsion that provides high performance and low hazards compared to state-of-art hydrazine are being investigated under NASA, DOD and commercially sponsored green propellant research and development programs. This NASA effort looks at phosphate stabilized 50% hydrogen peroxide/water –ethanol blends to evaluate their stability and combustion behavior in submillimeter diameter microtube combustion apparatus for cubesat propulsion applications. Exploratory 7-day stability tests find no pressure rise in a sealed test tube environment at room temperature indicating at least short term stability of the mixture. Temperature rise during combustion testing in resistively heated nickel microtube apparatus shows that micro-combustion is achieved in the tube. Propellant density is approximately 1.2 g/cu.cm compared to 1.0 g/cu.cm for hydrazine. Theoretical specific impulse of the stoichiometric blend is 219 s at a chamber pressure of 20 psia and an area ratio of 30:1. Density-specific impulse of this blend is 263 s while hydrazine is only about 215-220 s in small reaction control system thrusters. This provides about 20-22% more density-specific impulse for the cube sat compared to hydrazine. The the oretical combustion temperature is 2168°F, which is thermally compatible with stainless steel materials of construction and the nickel catalyst used in the tests. Combustion test results are given for stoichiometric, as well as fuel-lean and fuel-rich propellant formulations. These tests focus on thermally and catalytically supported combustion in the microtube, which requires a microtube preheat temperature of about 900°F and sufficient residence time to achieve combustion that is stable and anchored in the tube without blowing through the tube unreacted. Thrust class is expected to be in the 10 m N range based on flow rate and estimated specific impulse. Power requirements are generally below 25 W to heat the tube. Steady state combustion testing is typically conducted for 3 minutes and shows little degradation of the hardware over multiple test cycles indicating that there is little catalyst degradation over time and little catalyst deactivation due to the phosphate stabilizer in the hydrogen peroxide.

Monopropellant↗
DOE OSTI2020

Stabilization of Liner Implosions via a Dynamic Screw Pinch

Magnetically driven implosions are susceptible to magnetohydrodynamic instabilities, including the magneto-Rayleigh-Taylor instability (MRTI). To reduce MRTI growth in solid-metal liner implo-sions, the use of a dynamic screw pinch (DSP) has been proposed [P. F. Schmit et al., Phys. Rev. Lett. 117, 205001 (2016)]. In a DSP con guration, a helical return-current structure surrounds the liner, resulting in a helical magnetic eld that drives the implosion. Here, we present the rst experimental tests of a solid-metal liner implosion driven by a DSP. Using the 1-MA, 100{200-ns COBRA pulsed-power driver, we tested three DSP cases (with peak axial magnetic elds of 2 T, 14 T, and 20 T) and a standard z-pinch (SZP) case (with a straight return-current structure and thus zero axial eld). The liners had an initial radius of 3.2 mm and were made from 650-nm-thick aluminum foil. Images collected during the experiments reveal that helical MRTI modes developed in the DSP cases, while non-helical (azimuthally symmetric) MRTI modes developed in the SZP case. Additionally, the MRTI amplitudes for the 14-T and 20-T DSP cases were smaller than in the SZP case. Speci cally, when the liner had imploded to half of its initial radius, the MRTI amplitudes for the SZP case and for the 14-T and 20-T DSP cases were, respectively, 1.1-0.3 mm, 0.7-0.2 mm, and 0.3-0.1 mm. Relative to the SZP, the stabilization obtained using the DSP agrees reasonably well with theoretical estimates.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Continued Validation Studies using the MOOSE Framework for Plasma Simulation with Electromagnetics

Resources and tools for the modeling and simulation of low-temperature plasma (LTP) discharges are increasingly vital to progress in the field in order to properly characterize and study complex source designs and plasma chemistries beyond the scope of traditional diagnostics. Open-source software provides powerful platforms for this work and can enable community-driven LTP R&D. Within the Multiphysics Object-Oriented Simulation Environment (MOOSE) open-source framework [1], capabilities have been demonstrated in the areas of plasma fluids (Zapdos [2]), plasma chemistry (CRANE [3]), and general electromagnetic wave theory (Electromagnetic Library for Kinetics & fluids [ELK] [4]). ELK has since been coupled to Zapdos/CRANE to enable fully coupled electromagnetic plasma simulations. This talk will detail the continued validation efforts and discuss Zapdos-ELK-CRANE code coupling with various-low temperature plasma sources. The impact of fully coupled electromagnetics on process parameters (e.g., temperature and electron/ion energy) versus an electrostatic description will also be discussed. [1] Permann et al., SoftwareX, 11 (2020) 100430. [2] Lindsay et al., J. Phys. D: Appl. Phys. 49 (2016) 235204. [3] Keniley et al., Talk, GEC Session DT3.00002 (2019). [4] Icenhour et al., Talk, GEC Session RR1.00006 (2019). Acknowledgements: INL Graduate Fellowship Program, NSF SI2 Grant 1740300, U.S. Dept. of Energy Office of Science Graduate Student Research Program

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2001

A Radiation-Tolerant, Low-Power Non-Volatile Memory Based on Silicon Nanocrystal Quantum Dots

Nanocrystal nonvolatile floating-gate memories are a good candidate for space applications - initial results suggest they are fast, more reliable and consume less power than conventional floating gate memories. In the nanocrystal based NVM device, charge is not stored on a continuous polysilicon layer (so-called floating gate), but instead on a layer of discrete nanocrystals. Charge injection and storage in dense arrays of silicon nanocrystals in SiO2 is a critical aspect of the performance of potential nanocrystal flash memory structures. The ultimate goal for this class of devices is few- or single-electron storage in a small number of nanocrystal elements. In addition, the nanocrystal layer fabrication technique should be simple, 8-inch wafer compatible and well controlled in program/erase threshold voltage swing was seen during 100,000 program and erase cycles. Additional near-term goals for this project include extensive testing for radiation hardness and the development of artificial layered tunnel barrier heterostructures which have the potential for large speed enhancements for read/write of nanocrystal memory elements, compared with conventional flash devices. Additional information is contained in the original extended abstract.

Bell, L. D.↗
DOE OSTI2020

An Overview of Behind-the-Meter Solar-Plus-Storage Regulatory Design: Approaches and Case Studies to Inform International Applications

Behind-the-meter energy storage systems paired with distributed photovoltaic (DPV) - with the capability to act as both generation and load - represent a unique and disruptive power sector technology capable of providing a range of important services to customers, utilities, and the broader power system. How should regulators, utilities, and policymakers manage the range of challenges and opportunities that increased behind-the-meter energy storage deployment will bring to the power system, in particular when these systems are paired with DPV? This report is intended to offer key regulatory considerations for facilitating DPV-plus-storage programs for retail customers; relevant cases from U.S. states are provided as examples of how novel regulatory issues related to behind-the-meter energy storage systems paired with DPV are being addressed in practice. At a high level, designing a regulatory framework that aligns DPV-plus-storage deployment with larger policy objectives requires thoughtful deliberation across a range of technical and economic issues. While this report attempts to segment many of these issues into distinct topics to enhance reader understanding, in reality, DPV-plus-storage regulatory issues are all closely integrated, and design decisions on a single aspect often have broader implications. With that in mind, this report outlines a series of steps that can be employed by regulators to approach DPV-plus-storage regulatory design.

14 SOLAR ENERGY↗
DOE OSTI2020

Inflation and Dark Energy from spectroscopy at $\mathcal{z} > 2$

The expansion of the Universe is understood to have accelerated during two epochs: in its very first moments during a period of Inflation and much more recently, at $\mathcal{z} < 1$, when Dark Energy is hypothesized to drive cosmic acceleration. The undiscovered mechanisms behind these two epochs represent some of the most important open problems in fundamental physics. Most of the processes involved during Inflation impact observations on the very largest spatial scales. Traditionally, these have been accessed through observations of the Cosmic Microwave Background (CMB). While very powerful, the CMB originates from a 2D surface and the finite number of modes that it contains will largely be measured by experiments over the next decade. Observations of large 3D volumes with large-scale structure (LSS) access similar scales and will dramatically increase the number of available modes. For example, LSS observations in the range $2 \lesssim z \lesssim 5$ can more than triple the volume surveyed at $z \lesssim 2$, and, together with the sufficiently high galaxy number in this interval, strongly motivates a future spectroscopic survey that exploits this opportunity. In addition, tomography allows mapping the growth of structure with redshift, which provides robust constraints on Dark Energy and neutrino masses while relaxing restrictive assumptions such as a power-law primordial power spectrum. Finally, cross-correlation with external tracers, such as CMB lensing, Intensity Mapping or the Lyman-$\alpha$ forest, immunises the constraints to the systematics that make measurement challenging and further improves the precision through ‘sample variance cancellation’ and degeneracy breaking.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Potential for large-scale deployment of offshore wind-to-hydrogen systems in the United States

This study explores the role of producing low-carbon hydrogen using water electrolysis powered by offshore wind in facilitating the United States’ transition to a net-zero emissions economy by 2050. This research introduces an open-source scenario analysis tool for offshore wind-to-hydrogen systems, aiming to assess the impact of technology, regional considerations, and policy incentives on the cost of producing low-carbon hydrogen through offshore wind. Conducting a regional techno-economic analysis at four U.S. coastal sites, the study evaluates two energy transmission configurations and examines associated costs for the years 2025, 2030, and 2035. The results highlight that locations using fixed-bottom technology may achieve cost-competitive water electrolysis hydrogen production by 2030 through leveraging geologic hydrogen storage and federal policy incentives. Furthermore, floating technology locations are expected to see an average 38% reduction in the levelized cost of hydrogen from 2025 to 2035.

17 WIND ENERGY↗
NASA NTRS2005

Advanced Three-Dimensional Display System

A desktop-scale, computer-controlled display system, initially developed for NASA and now known as the VolumeViewer(TradeMark), generates three-dimensional (3D) images of 3D objects in a display volume. This system differs fundamentally from stereoscopic and holographic display systems: The images generated by this system are truly 3D in that they can be viewed from almost any angle, without the aid of special eyeglasses. It is possible to walk around the system while gazing at its display volume to see a displayed object from a changing perspective, and multiple observers standing at different positions around the display can view the object simultaneously from their individual perspectives, as though the displayed object were a real 3D object. At the time of writing this article, only partial information on the design and principle of operation of the system was available. It is known that the system includes a high-speed, silicon-backplane, ferroelectric-liquid-crystal spatial light modulator (SLM), multiple high-power lasers for projecting images in multiple colors, a rotating helix that serves as a moving screen for displaying voxels [volume cells or volume elements, in analogy to pixels (picture cells or picture elements) in two-dimensional (2D) images], and a host computer. The rotating helix and its motor drive are the only moving parts. Under control by the host computer, a stream of 2D image patterns is generated on the SLM and projected through optics onto the surface of the rotating helix. The system utilizes a parallel pixel/voxel-addressing scheme: All the pixels of the 2D pattern on the SLM are addressed simultaneously by laser beams. This parallel addressing scheme overcomes the difficulty of achieving both high resolution and a high frame rate in a raster scanning or serial addressing scheme. It has been reported that the structure of the system is simple and easy to build, that the optical design and alignment are not difficult, and that the system can be built by use of commercial off-the-shelf products. A prototype of the system displays an image of 1,024 by 768 by 170 (=133,693,440) voxels. In future designs, the resolution could be increased. The maximum number of voxels that can be generated depends upon the spatial resolution of SLM and the speed of rotation of the helix. For example, one could use an available SLM that has 1,024 by 1,024 pixels. Incidentally, this SLM is capable of operation at a switching speed of 300,000 frames per second. Implementation of full-color displays in future versions of the system would be straightforward: One could use three SLMs for red, green, and blue, respectively, and the colors of the voxels could be automatically controlled. An optically simpler alternative would be to use a single red/green/ blue light projector and synchronize the projection of each color with the generation of patterns for that color on a single SLM.

Geng, Jason↗