Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “FLEXIBILITY”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Lattice expansion and ligand twist during CO2 adsorption in flexible Cu bipyridine metal–organic frameworks

Flexible metal–organic frameworks (MOFs) can show exceptional selectivity and capacity for adsorption of CO 2 . The incorporation of CO 2 into flexible MOFs that have Cu 2+ coordination centers and organic pillar ligands is accompanied by a distortion of the framework lattice arising from chemical interactions between these components and CO 2 molecules. CO 2 adsorption yields a reproducible lattice expansion that is enabled by the rotation of the pillar ligands. The structures of Cu 2 (pzdc) 2 (bpy) and Cu 2 (pzdc) 2 (bpe), CPL-2 and CPL-5, were evaluated using in situ synchrotron X-ray powder diffraction at room temperature at CO 2 gas pressures up to 50 atm. The structural parameters exhibit hysteresis between pressurization and depressurization. The pore volume within CPL-2 and CPL-5 increases at elevated CO 2 pressure due to a combination of the pillar ligand rotation and the overall expansion of the lattice. Volumetric CO 2 adsorption measurements up to 50 atm reveal adsorption behavior consistent with the structural results, including a rapid uptake of CO 2 at low pressure, saturation above 20 atm, and hysteresis evident as a retention of CO 2 during depressurization. Finally, a significantly greater CO 2 uptake is observed in CPL-5 in comparison with predictions based on CO 2 pressure-induced expansion of the pore volume available for adsorption, indicating that the flexibility of the CPL structures is a key factor in enhancing adsorption capacity.

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

Plasma jet printing for flexible substrates

Recent interest in flexible electronics and wearable devices has created a demand for fast and highly repeatable printing processes suitable for device manufacturing. Robust printing technology is critical for the integration of sensors and other devices on flexible substrates such as paper and textile. An atmospheric pressure plasma-based printing process has been developed to deposit different types of nanomaterials on flexible substrates. Multiwalled carbon nanotubes were deposited on paper to demonstrate site-selective deposition as well as direct printing without any type of patterning. Plasma-printed nanotubes were compared with non-plasma-printed samples under similar gas flow and other experimental conditions and found to be denser with higher conductivity. The utility of the nanotubes on the paper substrate as a biosensor and chemical sensor was demonstrated by the detection of dopamine, a neurotransmitter, and ammonia, respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1972

Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations. Phase 6-A: Effects of blade torsion, of blade flap bending flexibility and of rotor support flexibility on rotor stability and random response

The effects of lifting rotor blade torsion, blade flap bending flexibility and rotor support flexibility on rotor stability and random response are described. The subjects discussed are: (1) blade representation and method of analysis, (2) random gust response statistics for coupled torsion-flapping rotor blade vibrations, (3) flap bending corrections to the rigid blade analysis of lifting rotors, and (4) effects of rotor support flexibility. The response of linear periodically time varying systems to random excitation is examined.

Hohenemser, K. H.↗
NASA NTRS1991

Control of a small working robot on a large flexible manipulator for suppressing vibrations: Development of a robust control law for flexible robot and it's stability analysis

Researchers developed a robust control law for slow motions for the accurate trajectory control of a flexible robot. The control law does not need larger velocity gains than position gains, which some researchers need to ensure the stability of a rigid robot. Initial experimentation for the Small Articulated Manipulator (SAM) shows that control laws that use smaller velocity gains are more robust to signal noise than the control laws that use larger velocity gains. Researchers analyzed the stability of the composite control law, the robust control for the slow motion, and the strain rate feedback for the fast control. The stability analysis was done by using a quadratic Liapunov function. Researchers found that the flexible motion of links could be controlled by relating the input force to the flexible signals which are sensed at the near tip of each link. The signals are contaminated by the time delayed input force. However, the effect of the time delayed input force can be reduced by giving a certain configuration to the SAM.

Soo, Han Lee↗
NASA NTRS2001

The Evolution of Flexible Insulation as Thermal Protection Systems for Reusable Launch Vehicles: AFRSI (Advanced Flexible Reusable Surface Insulation) to CRI (Conformal Reusable Insulation)

This viewgraph presentation gives an overview of the evolution of flexible insulation as a thermal protection system for reusable launch vehicles, Advanced Flexible Reusable Surface Insulation (AFRSI) to Conformal Reusable Insulation (CRI). Details are given on the approved use of AFRIS on the Shuttle Orbiter in June 1980, the first flight of AFRIS on STS-6, windward blanket development, composite flexible blanket insulation, and flight demonstrations.

Rezin, Marc↗
DOE OSTI2020

Flexible Electronics: Flexible Electrochemical Bioelectronics: The Rise of In Situ Bioanalysis (Adv. Mater. 15/2020)

Flexible electrochemical bioelectronics enables in situ quantification of a variety of chemical constituents present in the human body. It holds great promise for personalized health monitoring owing to its inherent wearability, high performance, and low cost. In article number 1902083, Wei Gao, Ali Javey, and co-authors summarize recent key innovations in flexible electrochemical bioelectronics from electrochemical sensing modalities, materials, systems, fabrication, to applications and discuss the challenges and opportunities in this field moving forward toward future preventive and personalized medicine devices.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Simulating Enhanced Methane Deliverable Capacity of Guest Responsive Pores in Intrinsically Flexible MOFs

In this work, a novel computational procedure, based on the principles of flat-histogram Monte Carlo, is developed for facile prediction of the adsorption thermodynamics of intrinsically flexible adsorbents. We then demonstrate how an accurate prediction of methane deliverable capacity in a metal–organic framework (MOF) with significant intrinsic flexibility requires use of such a method. Dynamic side chains in the framework respond to methane adsorbates and reorganize to exhibit a more conducive pore space at high adsorbate densities while simultaneously providing a less conducive pore space at low adsorbate densities. This “responsive pore” MOF achieves ~20% higher deliverable capacity than if the framework were rigid and elucidates a strategy for designing high deliverable capacity MOFs in the future.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Flexible Financial Credit Agreements: NREL Low- and Moderate-Income Solar Flexible Financing Credit Agreement Rubric

Flexible Financial Credit Agreements is a broad term used to describe a suite of solar products with innovative features not currently offered in traditional solar financing programs. The NREL Low- and Moderate-Income Solar Flexible Financing Credit Agreement Rubric brief document is designed to help evaluate innovative strategies for increasing the accessibility of solar and increasing adoption among LMI households. The rubric is modeled after a version developed to support plug-in electric vehicle policy adoption (NASEO and Cadmus).

ENERGY PLANNING, POLICY, AND ECONOMY,SOLAR ENERGY↗
DOE OSTI2016

Flexible Zirconium Metal‐Organic Frameworks as Bioinspired Switchable Catalysts

Abstract Flexible metal–organic frameworks (MOFs) are highly desirable in host–guest chemistry owing to their almost unlimited structural/functional diversities and stimuli‐responsive pore architectures. Herein, we designed a flexible Zr‐MOF system, namely PCN‐700 series, for the realization of switchable catalysis in cycloaddition reactions of CO 2 with epoxides. Their breathing behaviors were studied by successive single‐crystal X‐ray diffraction analyses. The breathing amplitudes of the PCN‐700 series were modulated through pre‐functionalization of organic linkers and post‐synthetic linker installation. Experiments and molecular simulations confirm that the catalytic activities of the PCN‐700 series can be switched on and off upon reversible structural transformation, which is reminiscent of sophisticated biological systems such as allosteric enzymes.

Yuan, Shuai↗
DOE OSTI2017

Freestanding NiFe Oxyfluoride Holey Film with Ultrahigh Volumetric Capacitance for Flexible Asymmetric Supercapacitors

In this work, a freestanding NiFe oxyfluoride (NiFeOF) holey film was prepared by electrochemical deposition and anodic treatments. With the combination of good electrical conductivity and holey structure, the NiFeOF holey film offers superior electrochemical performance, due to the following reasons: (i) The residual metal alloy framework can be used as the current collector to improve electrode conductivity. Moreover, the as-prepared freestanding NiFeOF holey film can be used as a supercapacitor electrode without reliance on binders and other additives. The residual metal alloy framework and binder-free electrode effectively reduces electrode resistance, thus improving electron transport. (ii) The highly interconnected holey structure and hierarchical pore distribution provides a high specific surface area to improve electron transport, enhancing rapid ion transport and mitigating diffusion limitations throughout the holey film. (iii) The excellent mechanical characteristics facilitate flexibility and cyclability related performance. Additionally, the NiFeOF holey film presents exceptional electrochemical performance, showing that it is a promising alternative for small/micro-size electronic devices.

holey film↗