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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 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Mechanisms Underlying a Quantum Superposition Microscope Based on THz-Driven Coherent Oscillations in a Two-Level Molecular Sensor

Here we report pump-probe measurements of a hydrogen molecule (H 2 ) in the tunnel junction of a scanning tunneling microscope (STM) coupled to ultrashort terahertz (THz) pulses. The coherent oscillation of the THz induced DC tunneling current at a frequency of ~0.5 THz fingerprints the absorption by H 2 as a two-level system (TLS). Two components of the oscillatory signal are observed and point to both photon and field aspects of the THz pulses. A few loosely bound states with similar energies for the upper state of the TLS are evidenced by the coherent revival of oscillatory signal. Furthermore, the comparison of spectroscopic features of H 2 with different tips provides an understanding of the TLS for H 2 .

36 MATERIALS SCIENCE↗
DOE OSTI2018

Dirac particle in Riemann-Cartan spacetimes

Dynamics of a Dirac particle in general Riemann-Cartan spacetimes is considered. The Hermitian Dirac Hamiltonian is derived and is transformed to the Foldy-Wouthuysen representation for an arbitrary spacetime geometry. The contribution of the torsion field to the Foldy-Wouthuysen Hamiltonian is found. The new bounds on Cartan’s spacetime torsion are obtained.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Visible and Dark Groups of Spacetime

A remarkable correspondence exists between lattices generated by discrete Jordan algebras and symmetries of superstrings, strongly suggesting that all known superstring theories are related and descend from a more general theory related to the Conway–Sloane transhyperbolic group. Cartan tori has visible spaces and G/ H Cartan generators as dark builders of G and determined by root lattices. E{sub 10} is shown as the dark group of the visible (9 + 1) space time with the Lorentz group O(9+1). Embedding of the higher exceptional groups will also be presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Finite Mathematics, Finite Quantum Theory and a Conjecture on the Nature of Time

We first give a rigorous mathematical proof that classical mathematics (involving such notions as infinitely small/large, continuity etc.) is a special degenerate case of finite one in the formal limit when the characteristic p of the field or ring in finite mathematics goes to infinity. We consider a finite quantum theory (FQT) based on finite mathematics and prove that standard continuous quantum theory is a special case of FQT in the formal limit p→∞. The description of states in standard quantum theory contains a big redundancy of elements: the theory is based on real numbers while with any desired accuracy the states can be described by using only integers, i.e. rational and real numbers play only auxiliary role. Therefore, in FQT infinities cannot exist in principle, FQT is based on a more fundamental mathematics than standard quantum theory and the description of states in FQT is much more thrifty than in standard quantum theory. Space and time are purely classical notions and are not present in FQT at all. In the present paper we discuss how classical equations of motions arise as a consequence of the fact that p changes, i.e. p is the evolution parameter. It is shown that there exist scenarios when classical equations of motion for cosmological acceleration and gravity can be formulated exclusively in terms of quantum quantities without using space, time and standard semiclassical approximation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Inverse problem: What can we tell about the matter and energy in our Universe from its dimensionality and evolution

The most well-known theories of everything are assorted versions of the superstring theory. The theories require existence of additional space dimensions, vibrations of which create the material particles in 3D space. The additional space dimensions are understood as being currently smaller than the Planck Length and due to this not directly observable. We search for multidimensional models of the Universe (one time dimension; three isotropic, flat external dimensions, and n-internal dimensions), which satisfy the multidimensional Einstein equations and which started from the same radius of all of the internal and external dimensions, with an anisotropic energy–momentum tensor. Analytical solution of (N+1)-dimensional Einstein equation in a reparameterized time is reminded and discussed. The energy–momentum tensor is solely responsible for expansion of the external dimensions and shrinking of the internal ones; and to obtain this behavior of the space the tensor needs to fulfill some conditions i.e. the energy–momentum tensor cannot include only radiation, vacuum and baryonic matter. For the behavior of the physical space consistent with the one observed in our Universe, the dark energy and/or dark matter have to exist.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Decomposing the Train-Scheduling Problem into Integer-Optimal Polytopes

This paper presents conditions for which the linear relaxation for the train-scheduling problem is integer optimal. These conditions are then used to identify how to partition a general problem’s feasible region into integer-optimal polytopes. Such an approach yields an extended formulation that contains far fewer binary variables. Our computational experiments show that this approach results in significant computational savings. Moreover, this approach scales well when the train-scheduling problem is modeled using smaller time increments, allowing for higher fidelity models to be solved without significantly increasing the required computational time.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1965

Experiment m-3, inflight exerciser on gemini iv

Evaluation of general physical condition of Gemini IV flight crew with increasing time under space flight conditions - response of cardiovascular system to calibrated workload

CARDIOVASCULAR SYSTEM↗
NASA NTRS2015

2nd-Order CESE Results For C1.1: Transonic Ringleb Flow

The Conservation Element and Solution Element (CESE) method was used as implemented in the NASA research code ez4d (an unstructured Navier-Stokes solver coded in C++ with serial and parallel versions available.) The CESE method is a time-accurate formulation with flux-conservation in both space and time. The method treats the discretized derivatives of space and time identically and while the 2nd-order accurate version was used, high-order versions exist.

Numerical Analysis↗