Attitude Control of a Satellite in Circular Orbit
Fuel optimal control conditions in attitude correction of satellite in circular orbit determined using maximum principle, solving resulting boundary value problem
FUEL CONSUMPTION↗
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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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Magnetically induced circular dichroism and birefringence in single lines of the electronic spectrum of ICl.
Magnetically induced circular dichroism and birefringence in ICl electronic spectrum, noting frequency dependence and molecular rotation effect
ELECTRON SPECTRUM↗
Some problems of thin circular cylindrical shells. I.
Simplified equations for thin circular cylindrical shells under loading investigated for possible elimination of inconsistencies
THIN WALLED SHELL↗
Bending Tests of Circular Cylinders of Corrugated Aluminum-alloy Sheet
Bending tests were made of two circular cylinders of corrugated aluminum-alloy sheet. In each test failure occurred by bending of the corrugations in a plane normal to the skin. It was found, after analysis of the effect of short end bays, that the computed stress on the extreme fiber of a corrugated cylinder is in excess of that for a flat panel of the same basic pattern and panel length tested as a pin-ended column. It is concluded that this increased strength was due to the effects of curvature of the pitch line. It is also concluded from the tests that light bulkheads closely spaced strengthen corrugated cylinders very materially.
STRESSED SKIN - CYLINDERS, CIRCULAR - BENDING↗
On the circulatory subsonic flow of a compressible fluid past a circular cylinder
The circulatory subsonic flow around an infinite circular cylinder is computed using the linearized pressure-volume relation, by a method developed in a previous report. Formulas and graphs are given for the velocity and pressure distributions, the circulation, the lift, and the dependence of the critical Mach number upon the position of the stagnation point.
FLOW, COMPRESSIBLE-MEASUREMENT↗
Measurements in Flight of the Lateral-Control Characteristics of an Airplane Equipped with Full-Span Zap Flaps and Simple Circular-Arc-Type Ailerons
Flight tests were conducted on the OS2U-2 seaplane with simple circular-arc-type ailerons directly connected to the actuating torque tube. Two aileron test installations were made, differing only in the inclination of the projecting surface with the wing's upper surface. The lateral-control characteristics of the airplane were determined from data obtained in stalls and rudder-fixed aileron rolls. The revised ailerons were deficient in maximum rolling effectiveness, but were capable of controlling the rolling tendencies of the airplane near the stall.
AILERON CONTROLS - VOUGHT OS2U-2↗
On the mechanism of buckling of a circular cylindrical shell under axial compression
The present paper deals with the buckling of a circular cylindrical shell under axial compression from the viewpoint of energy and the characteristics of deformation. It is shown first, both theoretically and experimentally, that the reason why the buckling of a cylindrical shell is quite different from that of a flat plate is attributable to the existence of a nearly developable surface far apart from the original cylindrical surface. Based upon this result, the experimental fact that the buckling is really not general but local, that is, that the buckled region is limited axially to a range of 1.5 times the wave length of the lobe, is explained by the theoretical result that the minimum buckling load is smaller in the local buckling than in the general buckling case. The occurrence of local buckling is affirmed also from the viewpoint of the energy barrier to be jumped over during buckling, and from a comparison of the theoretical post-buckling state with the experimental results. Finally, the local buckling with the load applied by a spring is analyzed, and it is proved that the minimum buckling load increased with an increase of rigidity of the spring.
SHELLS, STRUCTURAL↗
On the Existence of Subharmonic Screech in Choked Circular Jets from a Sharp-Edged Orifice
Experiments are performed in choked circular hot and cold nitrogen jets issuing from a 2.44 cm diameter sharp-edged orifice at a fully expanded jet Mach number of 1.85 in an effort to investigate the character of screech phenomenon. The stagnation temperature of the cold and the hot jets are 299 K and 319 K respectively. The axial distribution of the centerline Mach number was obtained with a pitot tube, while the screech data (frequency and amplitude) at different axial and radial stations were measured with the aid of microphones. The fundamental screech frequency of the hot jet is slightly increased relative to that of the cold jet. It is concluded that temperature effects on the screech amplitude are manifested with regard to the fundamental and the subharmonic even at relatively small temperature range considered.
Circular Jets↗
The Solar Poynting-Robertson Effect On Particles Orbiting Solar System Bodies: Circular Orbits
The Poynting-Robertson effect from sunlight impinging directly on a particle which orbits a Solar System body (planet, asteroid, comet) is considered from the Sun's rest frame. There appear to be no significant first-order terms in V(sub b)/c for circular orbits, where V(sub b) is the body's speed in its orbit about the Sun and c is the speed of light, when the particle's orbital semimajor axis is much smaller than the body's orbital semimajor axis about the Sun as is mainly the case in the Solar System.
circular orbits↗
Closing the Loop on Space Trash / Is a Circular Economy Possible?
A crew member will nominally consume 2.5 kg of water per crew-member per day, rejectapproximately 0.032 kg of dry fecal solid waste per crew member per day (dry basis)and generate approximately 2,122 kg of logistical waste per year on a long-durationcrewed mission. This topic seeks to push the conversation towards completing a closedloop system and circular economy for all materials and recoverable resources withregard to waste management, regenerative water use, and recycling. In all aspects,reduction of crew maintenance time, mass, power and volume are at the forefront oftechnology development. In addition, the longevity and hardware robustness is important(lasting >3 years). Overall water recovery of >98% is desired, as well as, condensingheat exchangers that remove water from air with collection rates up to 1.45 kg of waterper hour. There are many technologies on the ground being developed for recycling andtrash management or regenerative water use that have yet to introduce themselves forspace development and infusion. Here we look to open the conversation and cross cutthese platforms to bring out some innovation and exposure into the hidden crevasses ofthe waste that humans create and how to minimize it/repurpose it, for all of humanity.
ISRU↗
Waste Management, Circular Economy and Life Cycle Assessment
This presentation covers analysis research strategies and approaches for life cycle assessment, circular economy and waste management.
circular economy↗
A Circular and Tacticity‐Independent Crystalline Mono‐Substituted Nylon‐6 Platform: Unexpected Large Positional Effects on Crystallizability and Performance
Seeking recyclable, more sustainable alternatives to nylon 6 has drawn much attention, but achieving its variants with both crystallinity and enhanced recyclability still remains a challenge. Here, by utilizing bio-derivable mono-substituted racemic lactam monomers, we reveal surprisingly large effects of methyl substitution positions on the nylon-6 backbone on crystallizability, thermomechanical performance, and recyclability of the resulting atactic nylon-6 variants. While γ-methyl substitution gives an amorphous nylon, all other four methyl-substitution positions (α, β, δ, and ε) afford, unexpectedly, crystalline nylons with melting temperatures ranging from 145°C to 200°C and tunable mechanical performance from being stiff and strong (α, ε) to ductile (β, δ). Investigations reveal that the crystallinity of atactic nylons arises independently of stereoregularity, which is driven by the amide backbone with robust hydrogen-bonding interactions and countered by the chain flexibility regulated by the substitution position. These nylons can be chemically recycled back to their parent monomers with high isolated yields up to 92%, enabling a circular, tacticity-independent crystalline nylon platform.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Magnetic Weyl semimetals as a source of circularly polarized THz radiation
We propose to use the electromagnetic radiation induced by a few MeV electron beam in magnetic Weyl semimetals as a source of the circularly polarized photons in the THz frequency range.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Thermal Oxo-degradation and Catalytic Upgrading of Plastic Waste to Light Olefins for a Circular Economy
The commercialization of conventional pyrolysis of plastic in an inert atmosphere has been hindered by large thermal requirements stemming from long reaction rates. The rate of thermal depolymerization of waste plastics can be accelerated by the addition of oxygen in a process known as thermal oxo-degradation (TOD). This study offers the prospect of TOD to upcycle postconsumer waste rapidly and efficiently. Using moderate temperatures and small amounts of air in a fluidized bed reactor, we demonstrated that waste high-density polyethylene and polypropylene are rapidly deconstructed to condensable products. These condensable products were catalytically upgraded in a micropyrolysis reactor using commercially available zeolite (HZSM-5) to monomeric olefins. The olefin yields proved to be greater than those achieved through the catalytic upgrading of condensable products from (nonoxidative) the pyrolysis of the same plastic wastes. The coupling of TOD with catalytic upgrading proves to be an energy-efficient pathway in a plastics circular economy for the production of light olefins from wastes.
Enthalpy↗
Exact-Two-Component Complete Active Space Method with Variational Treatment of Magnetic Field and Spin–Orbit Coupling: Application to X-ray Magnetic Circular Dichroism Spectroscopy
We introduce an exact-two-component complete active space self-consistent-field (X2C-CASSCF) method formulated under the restricted-magnetic-balance condition. This framework allows for the nonperturbative treatment of static magnetic fields using gauge-including atomic orbitals (GIAOs). The GIAO-X2C-CASSCF methodology effectively captures all microstates within the same 2J + 1-degenerate manifold and their splitting in a static magnetic field, which are not accessible through single-reference-based methods. We also present mathematical recursive expressions for evaluating one-electron relativistic integrals by using GIAOs in the presence of a finite magnetic field. Benchmark studies include oxygen and nitrogen K-edge X-ray magnetic circular dichroism spectroscopy (XMCD) for closed-shell organic compounds, as well as L-edge XMCD spectroscopy for the high-spin open-shell transition metal ion Mn 2+ and the tetrahedral Mn(II)O 4 6– complex.
Chemical calculations↗
Optically Addressing Circularly Polarized Vibrations in Molecules
Circularly polarized (CP) vibrations are the nuclear-motion analog of CP light, emerging in molecules with non-Abelian point-group symmetry that support orthogonal and degenerate vibrational normal modes. Here, in this work, we theoretically explore the optical addressability of CP vibrations, motivated by their potential as nanoscale angular momentum states suitable for information storage and manipulation. We investigate how symmetry-breaking chemical modifications affect a molecule’s capacity to support CP vibrations. Notably, we find cases where modes retain their orthogonality and degeneracy in spite of such modifications, broadening the opportunities afforded by CP vibrations beyond non-Abelian point-group molecules. Prospects for experimental implementations using CP pump–probe techniques are briefly discussed.
group theory↗
Spin Polarization from Circularly Polarized Light Induced Charge Transfer
Here, we show how a spin polarization can be generated through the photoinduced electron transfer of an achiral donor–acceptor complex following chiral light excitation. In particular, we illustrate the basic energetic and symmetry requirements for chirality induced spin selectivity where the chirality emerges from the electronic degrees of freedom following excitation with circularly polarized light. We study this effect in a simple model of a metalloporphyrin complex with an axial acceptor ligand using quantum mechanical rate theories and numerical simulations. We find that the spin polarization emerges due to the selective excitation of a ring current within the porphryin, breaking the degeneracy of the two degenerate spin states. The resultant spin polarization increases with the spin orbit coupling between the metal in the porphyrin and the axial ligand, and is transient, with a lifetime dependent on the rate of dephasing from the Jahn–Teller distortion mode. This proposed effect should be observable in spin-resolved photoemission spectroscopy.
charge transfer↗
Correction to “Toward a Circular Bioeconomy: Designing Microbes and Polymers for Biodegradation”
Correction to “Toward a Circular Bioeconomy: Designing Microbes and Polymers for Biodegradation”
59 BASIC BIOLOGICAL SCIENCES↗