9,946 research outputs found
Mark 4A antenna control system data handling architecture study
A high-level review was conducted to provide an analysis of the existing architecture used to handle data and implement control algorithms for NASA's Deep Space Network (DSN) antennas and to make system-level recommendations for improving this architecture so that the DSN antennas can support the ever-tightening requirements of the next decade and beyond. It was found that the existing system is seriously overloaded, with processor utilization approaching 100 percent. A number of factors contribute to this overloading, including dated hardware, inefficient software, and a message-passing strategy that depends on serial connections between machines. At the same time, the system has shortcomings and idiosyncrasies that require extensive human intervention. A custom operating system kernel and an obscure programming language exacerbate the problems and should be modernized. A new architecture is presented that addresses these and other issues. Key features of the new architecture include a simplified message passing hierarchy that utilizes a high-speed local area network, redesign of particular processing function algorithms, consolidation of functions, and implementation of the architecture in modern hardware and software using mainstream computer languages and operating systems. The system would also allow incremental hardware improvements as better and faster hardware for such systems becomes available, and costs could potentially be low enough that redundancy would be provided economically. Such a system could support DSN requirements for the foreseeable future, though thorough consideration must be given to hard computational requirements, porting existing software functionality to the new system, and issues of fault tolerance and recovery
Quantum sensors based on weak-value amplification cannot overcome decoherence
Sensors that harness exclusively quantum phenomena (such as entanglement) can
achieve superior performance compared to those employing only classical
principles. Recently, a technique based on postselected, weakly-performed
measurements has emerged as a method of overcoming technical noise in the
detection and estimation of small interaction parameters, particularly in
optical systems. The question of which other types of noise may be combatted
remains open. We here analyze whether the effect can overcome decoherence in a
typical field sensing scenario. Benchmarking a weak, postselected measurement
strategy against a strong, direct strategy we conclude that no advantage is
achievable, and that even a small amount of decoherence proves catastrophic to
the weak-value amplification technique.Comment: Published version with improvements to presentation, including
clarifying our understanding of technical noise and quantum nois
Experimental study of solar cell performance at high solar intensities
Equilibrium temperatures for solar cell configurations bonded to, but thermally insulated from spinning spacecraf
Experimental study of coatings for temperature control of solar cells
Interference filters and highly reflective coatings for temperature control of solar cell
Electrically driven spin resonance in a bent disordered carbon nanotube
Resonant manipulation of carbon nanotube valley-spin qubits by an electric
field is investigated theoretically. We develop a new analysis of electrically
driven spin resonance exploiting fixed physical characteristics of the
nanotube: a bend and inhomogeneous disorder. The spectrum is simulated for an
electron valley-spin qubit coupled to a hole valley-spin qubit and an impurity
electron spin, and features that coincide with a recent measurement are
identified. We show that the same mechanism allows resonant control of the full
four-dimensional spin-valley space.Comment: 11 pages, 7 figure
Load programmer, static switches, and annunciator for inverters and converters
Load programmer, switches, and annunciator for static inverters and converters operating in paralle
Seeing opportunity in every difficulty: protecting information with weak value techniques
A weak value is an effective description of the influence of a pre and
post-selected 'principal' system on another 'meter' system to which it is
weakly coupled. Weak values can describe anomalously large deflections of the
meter, and deflections in otherwise unperturbed variables: this motivates
investigation of the potential benefits of the protocol in precision metrology.
We present a visual interpretation of weak value experiments in phase space,
enabling an evaluation of the effects of three types of detector noise as
'Fisher information efficiency' functions. These functions depend on the
marginal distribution of the Wigner function of the meter, and give a unified
view of the weak value protocol as a way of protecting Fisher information from
detector imperfections. This approach explains why weak value techniques are
more effective for avoiding detector saturation than for mitigating detector
jitter or pixelation.Comment: 17 pp, 4 figs, Quantum Stud.: Math. Found. (2018
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