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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Peppytides: Interactive Models of Polypeptide Chains

Peppytides are scaled, 3D-printed models of polypeptide chains that can be folded into accurate protein structures. Designed and created by Berkeley Lab Researcher, Promita Chakraborty, and Berkeley Lab Senior Scientist, Dr. Ron Zuckermann, Peppytides are accurate physical models of polypeptide chains that anyone can interact with and fold intro various protein structures - proving to be a great educational tool, resulting in a deeper understanding of these fascinating structures and how they function. Build your own Peppytide model and learn about how nature's machines fold into their intricate architectures!

3D PRINTING↗
DOE OSTI2022

Modeling and implementation of vertical excursion FFA in the Zgoubi ray-tracing code

Vertical Fixed Field Accelerators (vFFAs) feature complex and highly non-linear magnetic fields, which require simulation codes allowing step-wise particle tracking. Methods to model the 3D magnetic field of scaling vFFAs have been developed in the ray-tracing code Zgoubi. The field modeling and particle tracking methods include the field non-linearities, the fringe fields, and the field superposition of neighboring magnets. The procedure implements the vFFA analytical field expressions, allowing design studies and parameter optimizations using the Zgoubi built-in fit method. The vFFA procedure has been applied to a ten-fold symmetry ring with a triplet focusing structure designed to accelerate protons from 3 MeV to 12 MeV and studied under the ISIS-II proton driver prototype project. Results from particle tracking in externally generated 3D semi-analytical field maps and the developed vFFA analytical model are shown to be in excellent agreement.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Photonic density of states of two-dimensional quasicrystalline photonic structures

A large photonic band gap (PBG) is highly favorable for photonic crystal devices. One of the most important goals of PBG materials research is identifying structural design strategies for maximizing the gap size. We provide a comprehensive analysis of the PBG properties of two-dimensional (2D) quasicrystals (QCs), where rotational symmetry, dielectric fill factor, and structural morphology were varied systematically in order to identify correlations between structure and PBG width at a given dielectric contrast (13:1, Si:air). The transverse electric (TE) and transverse magnetic (TM) PBGs of 12 types of QCs are investigated (588 structures). We discovered a 12mm QC with a 56.5% TE PBG, the largest reported TE PBG for an aperiodic crystal to date. We also report here a QC morphology comprising ''throwing star''-like dielectric domains, with near-circular air cores and interconnecting veins emanating radially around the core. This interesting morphology leads to a complete PBG of {approx}20% , which is the largest reported complete PBG for aperiodic crystals.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Designing and transforming yield-stress fluids

We review progress in designing and transforming multi-functional yield-stress fluids and give a perspective on the current state of knowledge that supports each step in the design process. We focus mainly on the rheological properties that make yield-stress fluids so useful and the trade-offs which need to be considered when working with these materials. Thinking in terms of "design with" and "design of' yield-stress fluids motivates how we can organize our scientific understanding of this field. "Design with" involves identification of rheological property requirements independent of the chemical formulation, e.g. for 3D direct-write printing which needs to accommodate a wide range of chemistry and material structures. "Design of includes microstructural considerations: conceptual models relating formulation to properties, quantitative models of formulation-structureproperty relations, and chemical transformation strategies for converting effective yield-stress fluids to be more useful solid engineering materials. Finally, future research directions are suggested at the intersection of chemistry, soft-matter physics, and material science in the context of our desire to design useful Theologically-complex functional materials.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Forced diffusion via electrically induced crystallization for fabricating ZnO–Ti–Si structures

Highlights: • ZnO–Ti–Si system is very important for the structural design. • The electrically induced crystallization method is useful to diffusion process. • Intermetallic compound characteristics have been presented using electrically induced crystallization. • Interface mechanism about diffusion of TZO–TiSi{sub x}–Si structure is presented. - Abstract: Electrically induced crystallization (EIC) is a recently developed process for material modification. This study is applied to EIC to fabricate ZnO–Ti–Si multi-layer structures of various thicknesses to dope Ti into ZnO thin film and to form TiSi{sub x} intermetallic compound (IMC) in a single step. The IMC layer was confirmed using transmission electron microscopy images. The Ti layer thickness was more than 40 nm, which enhanced electron transmission and decreased the total electrical resistance in the structure. Finally, the diffusion mechanisms of EIC and the annealing process were investigated. This study shows that the EIC process has potential for industrial applications.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Reconfigurable and writable magnetic charge crystals

Artificial ices enable the study of geometrical frustration by design and through direct observation. It has, however, proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. An artificial spin structure design is described that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. A technique is also developed to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multi-functionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice provides a setting for designing magnetic monopole defects, tailoring magnetics and controlling the properties of other two-dimensional materials.

47 OTHER INSTRUMENTATION↗
DOE OSTI2015

Double Wall Framing Technique An Example of High Performance, Sustainable Building Envelope Technology

Double wall technologies utilizing wood framing have been well-known and used in North American buildings for decades. Most of double wall designs use only natural materials such as wood products, gypsum, and cellulose fiber insulation, being one of few building envelope technologies achieving high thermal performance without use of plastic foams or fiberglass. Today, after several material and structural design modifications, these technologies are considered as highly thermally efficient, sustainable option for new constructions and sometimes, for retrofit projects. Following earlier analysis performed for U.S. Department of Energy by Fraunhofer CSE, this paper discusses different ways to build double walls and to optimize their thermal performance to minimize the space conditioning energy consumption. Description of structural configuration alternatives and thermal performance analysis are presented as well. Laboratory tests to evaluate thermal properties of used insulation and whole wall system thermal performance are also discussed in this paper. Finally, the thermal loads generated in field conditions by double walls are discussed utilizing results from a joined project performed by Zero Energy Building Research Alliance and Oak Ridge National Laboratory (ORNL), which made possible evaluation of the market viability of low-energy homes built in the Tennessee Valley. Experimental data recorded in two of the test houses built during this field study is presented in this work.

Building Envelope↗
DOE OSTI2018

In-Situ Printing of Conductive Polylactic Acid (cPLA) Strain Sensors Embedded into Additively Manufactured Parts using Fused Deposition Modeling

Additive Manufacturing (AM) technology has been around for decades, but until recently, machines have been expensive, relatively large, and not available to most institutions. Increased technological advances in 3D printing and awareness throughout industry, universities, and even hobbyists has increased demand to substitute AM parts in place of traditionally manufactured (subtractive) designs; however, there is a large variability of part quality and mechanical behavior due to the inherent printing process, which must be understood before AM parts are used for load bearing and structural design.

42 ENGINEERING↗
DOE OSTI2020

Electro-mechanical Modeling of Wind Turbine and Energy Storage Systems with Enhanced Inertial Response

In this paper, a coordinated control scheme for wind turbine generator (WTG) and supercapacitor energy storage system (ESS) is proposed for temporary frequency supports. Inertial control is designed by using generator torque limit considering the security of WTG system, while ESS releases its energy to compensate the sudden active power deficit during the recovery process of turbine rotor. WTG is modeled using the fatigue, aerodynamic, structure, turbulence (FAST) code, which identifies the mechanical loadings of the turbine and addresses electro-mechanical interactions in the wind energy system. A damping controller is augmented to the inertial control to suppress severe mechanical oscillations in the shaft and tower of the turbine during frequency supports. Furthermore, the result of small-signal stability analysis shows that the WTG-ESS tends to improve the stability of the whole multi-energy power grid. The major contributions of this paper will be validated by utilizing the proposed control method that combines the grid support capability and maintaining the integrity of structural design of the turbine for normal operations.

17 WIND ENERGY↗
DOE OSTI2012

Effect of twinning on texture evolution of depleted uranium using a viscoplastic self-consistent model

Ductility and fracture toughness is a major stumbling block in using depleted uranium as a structural material. The ability to correctly model deformation of uranium can be used to create process path methods to improve its structural design ability. The textural evolution of depleted uranium was simulated using a visco-plastic self consistent model and analyzed by comparing pole figures of the simulations and experimental samples. Depleted uranium has the same structure as alpha uranium, which is an orthorhombic phase of uranium. Both deformation slip and twin systems were compared. The VPSC model was chosen to simulate this material because the model encompasses both low-symmetry materials as well as twinning in materials. This is of particular interest since depleted uranium has a high propensity for twinning, which dominates deformation and texture evolution. Simulated results were compared to experimental results to measure the validity of the model. One specific twin system, the {l_brace}176{r_brace}[512] twin, was of specific notice. The VPSC model was used to simulate the influence of this twin on depleted uranium and was compared with a mechanically shocked depleted uranium sample. Under high strain rate shock deformation conditions, the {l_brace}176{r_brace}[512] twin system appears to be a dominant deformation system. By simulating a compression process using the VPSC model with the {l_brace}176{r_brace}[512] twin as the dominant deformation mode, a favorable comparison could be made between the experimental and simulated textures. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Bird-Strike Analysis Using Eulerian Peridynamic Formulation

The purpose of this project between Sandia National Laboratories (SNL) and The Boeing Company (Boeing) was to develop an analysis capability for predicting the loads on aircraft structures due to the inflight impact of birds. The main technical accomplishment was the development and delivery to Boeing of a new software tool that predicts the pressure over a structure's surface area, as a function of time and impact conditions, during the impact. The benefit to Boeing, and to government agencies such as NASA and the FAA, is an accurate tool to help design structures to withstand potentially catastrophic damage due to bird strike.

42 ENGINEERING↗
DOE OSTI2023

Superior Capacitive Energy-Storage Performance in Pb-Free Relaxors with a Simple Chemical Composition

Chemical design of lead-free relaxors with simultaneously high energy density (W rec ) and high efficiency (η) for capacitive energy-storage has been a big challenge for advanced electronic systems. The current situation indicates that realizing such superior energy-storage properties requires highly complex chemical components. Herein, we demonstrate that, via local structure design, an ultrahigh W rec of 10.1 J/cm 3 , concurrent with a high η of 90%, as well as excellent thermal and frequency stabilities can be achieved in a relaxor with a very simple chemical composition. By introducing 6s 2 lone pair stereochemical active Bi into the classical BaTiO 3 ferroelectric to generate a mismatch between A- and B-site polar displacements, a relaxor state with strong local polar fluctuations can be formed. Through advanced atomic-resolution displacement mapping and 3D reconstructing the nanoscale structure from neutron/X-ray total scattering, it is revealed that the localized Bi enhances the polar length largely at several perovskite unit cells and disrupts the long-range coherent Ti polar displacements, resulting in a slush-like structure with extremely small size polar clusters and strong local polar fluctuations. This favorable relaxor state exhibits substantially enhanced polarization, and minimized hysteresis at a high breakdown strength. This work offers a feasible avenue to chemically design new relaxors with a simple composition for high-performance capacitive energy-storage.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Large-deformation and high-strength amorphous porous carbon nanospheres

Carbon is one of the most important materials extensively used in industry and our daily life. Crystalline carbon materials such as carbon nanotubes and graphene possess ultrahigh strength and toughness. In contrast, amorphous carbon is known to be very brittle and can sustain little compressive deformation. Inspired by biological shells and honeycomb-like cellular structures in nature, we introduce a class of hybrid structural designs and demonstrate that amorphous porous carbon nanospheres with a thin outer shell can simultaneously achieve high strength and sustain large deformation. The amorphous carbon nanospheres were synthesized via a low-cost, scalable and structure-controllable ultrasonic spray pyrolysis approach using energetic carbon precursors. In situ compression experiments on individual nanospheres show that the amorphous carbon nanospheres with an optimized structure can sustain beyond 50% compressive strain. Both experiments and finite element analyses reveal that the buckling deformation of the outer spherical shell dominates the improvement of strength while the collapse of inner nanoscale pores driven by twisting, rotation, buckling and bending of pore walls contributes to the large deformation.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Semiconductor activated terahertz metamaterials

Metamaterials have been developed as a new class of artificial effective media realizing many exotic phenomena and unique properties not normally found in nature. Metamaterials enable functionality through structure design, facilitating applications by addressing the severe material issues in the terahertz frequency range. Consequently, prototype functional terahertz devices have been demonstrated, including filters, antireflection coatings, perfect absorbers, polarization converters, and arbitrary wavefront shaping devices. Further integration of functional materials into metamaterial structures have enabled actively and dynamically switchable and frequency tunable terahertz metamaterials through the application of external stimuli. The enhanced light-matter interactions in active terahertz metamaterials may result in unprecedented control and manipulation of terahertz radiation, forming the foundation of many terahertz applications. In this paper, we review the progress during the past few years in this rapidly growing research field. We particularly focus on the design principles and realization of functionalities using single-layer and few-layer terahertz planar metamaterials, and active terahertz metamaterials through the integration of semiconductors to achieve switchable and frequency-tunable response.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Specifying structural constraints of architectural patterns in the ARCHERY language

ARCHERY is an architectural description language for modelling and reasoning about distributed, heterogeneous and dynamically reconfigurable systems in terms of architectural patterns. The language supports the specification of architectures and their reconfiguration. This paper introduces a language extension for precisely describing the structural design decisions that pattern instances must respect in their (re)configurations. The extension is a propositional modal logic with recursion and nominals referencing components, i.e., a hybrid µ-calculus. Its expressiveness allows specifying safety and liveness constraints, as well as paths and cycles over structures. Refinements of classic architectural patterns are specified.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

3D TiO{sub 2} submicrostructures decorated by silver nanoparticles as SERS substrate for organic pollutants detection and degradation

Graphical abstract: - Highlights: • Contrive a multifunctional SERS substrate with 3D sub-micrometer structure and multicomponent. • The blue wing of butterfly (Euploea mulciber) is used as template for Ag/TiO{sub 2} nanocomposites. • The 3D submicrostructures Ag/TiO{sub 2} presents superior SERS effect and photocatalytic activity. • Pave a facile route to prepare multifunctional material by utilizing smart structural designs in nature. - Abstract: The blue wing of butterfly Euploea mulciber is used as a template to generate Ag/TiO{sub 2} nanocomposites. Thereinto, Ag nanoparticles are deposited uniformly onto TiO{sub 2} substrate with three dimensional (3D) submicrometer structures. This unique 3D sub-micrometer structures featured with ridges, ribs and struts can provide a large number of active “hot spots” for enhanced Raman signal. Meanwhile, depositing Ag onto the TiO{sub 2} surface can greatly boost its SERS effect and photocatalytic activity by bringing additional electrons into the molecules and inhibiting electrons–holes recombination. Thus, the as-prepared 3D Ag/TiO{sub 2} submicrostructures can not only offer sensitive and reproducible SERS signals, but also present superior photocatalytic activity, which can be utilized to detect and eliminate organic pollutants.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Additive manufacturing of continuous carbon fiber-reinforced SiC ceramic composite with multiple fiber bundles by an extrusion-based technique

Due to the high cost, complex preparation process and difficulty in structural design, the traditional methods for carbon fiber-reinforced SiC ceramic composite preparation have great limitations. This paper presents a technique for the additive manufacturing multiple continuous carbon fiber bundle-reinforced SiC ceramic composite with core-shell structure using an extrusion-based technique. A conventional nozzle system was modified to print simultaneously a water-based SiC paste with continuous carbon fibers. Different levels of binder contents were investigated to optimize the stickiness, viscosity, thixotropy and viscoelasticity of the paste. After sintering, SiC whiskers were generated on the surface of fiber, which is conjectured to be due to the reaction between SiO and carbon fiber at high temperature. The continuous carbon fiber-reinforced SiC ceramic composite exhibited non-brittle fracture. In conclusion, the flexural strength of the additively manufactured Cf/SiC composites improved from 162 MPa with no fiber bundles to a maximum of 219 MPa with three fiber bundles.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Characterization of 2.3 μm GaInAsSb-based vertical-cavity surface-emitting laser structures using photo-modulated reflectance

We report angle dependent and temperature dependent (9 K–300 K) photo-modulated reflectance (PR) studies on vertical-cavity surface-emitting laser (VCSEL) structures, designed for 2.3 μm mid-infrared gas sensing applications. Changing the temperature allows us to tune the energies of the quantum well (QW) transitions relative to the VCSEL cavity mode (CM) energy. These studies show that this VCSEL structure has a QW-CM offset of 21 meV at room temperature. Consequently the QW ground-state transition comes into resonance with the CM at 220 ± 2 K. The results from these PR studies are closely compared with those obtained in a separate study of actual operating devices and show how the PR technique may be useful for device optimisation without the necessity of having first to process the wafers into working devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗