19,157 research outputs found
Multiloop Manual Control of Dynamic Systems
Human interaction with a simple, multiloop dynamic system in which the human's activity was systematically varied by changing the levels of automation was studied. The control loop structure resulting from the task definition parallels that for any multiloop manual control system, is considered a sterotype. Simple models of the human in the task, and upon extending a technique for describing the manner in which the human subjectively quantifies his opinion of task difficulty were developed. A man in the loop simulation which provides data to support and direct the analytical effort is presented
Turbojet blade vibration data acquisition design and feasibility testing
A turbojet blade vibration data acquisition system was designed to allow the measurement of blade vibration. The data acquisition system utilizing 96 microprocessors to gather data from optical probes, store, sort and transmit to the central computer is described. Areas of high technical risk were identified and a two-microprocessor system was breadboarded and tested to investigate these areas. Results show that the system was feasible and that low technical risk would be involved in proceeding with the complete system fabrication
Passive propellant system
The system utilizes a spherical tank structure A separated into two equal volume compartments by a flat bulkhead B. Each compartment has four similar gallery channel legs located in the principal vehicle axes, ensuring that bulk propellant will contact at least one gallery leg during vehicle maneuvers. The forward compartment gallery channel legs collect propellant and feed it into the aft compartment through communication screens which protrude into the aft compartment. The propellant is then collected by the screened gallery channels in the aft compartment and supplied to the propellant outlet. The invention resides in the independent gallery assembly and screen structure by means of which propellant flow from forward to aft compartments is maintained. Liquid surface tension of the liquid on the screens is used to control liquid flow. The system provides gas-free propellants in low or zero-g environments regardless of axial accelerations and propellant orientation in bulk regions of the vessel
Excimer lasers
A theoretical and experimental investigation into the possibility of achieving CW discharge pumped excimer laser oscillation is reported. Detailed theoretical modeling of capillary discharge pumping of the XeF and KXe and K2 excimer systems was carried out which predicted the required discharge parameters for reaching laser threshold on these systems. Capillary discharge pumping of the XeF excimer system was investigated experimentally. The experiments revealed a lower excimer level population density than predicted theoretically by about an order of magnitude. The experiments also revealed a fluorine consumption problem in the discharge in agreement with theory
Comment on "Exclusion of time in the theorem of Bell" by K. Hess and W. Philipp
A recent Letter by Hess and Philipp claims that Bell's theorem neglects the
possibility of time-like dependence in local hidden variables, hence is not
conclusive. Moreover the authors claim that they have constructed, in an
earlier paper, a local realistic model of the EPR correlations. However, they
themselves have neglected the experimenter's freedom to choose settings, while
on the other hand, Bell's theorem can be formulated to cope with time-like
dependence. This in itself proves that their toy model cannot satisfy local
realism, but we also indicate where their proof of its local realistic nature
fails.Comment: Latex needs epl.cl
Excimer lasers
The results of a two-year investigation into the possibility of developing continuous wave excimer lasers are reported. The program included the evaluation and selection of candidate molecular systems and discharge pumping techniques. The K Ar/K2 excimer dimer molecules and the xenon fluoride excimer molecule were selected for study; each used a transverse and capillary discharges pumping technique. Experimental and theoretical studies of each of the two discharge techniques applied to each of the two molecular systems are reported. Discharge stability and fluorine consumption were found to be the principle impediments to extending the XeF excimer laser into the continuous wave regime. Potassium vapor handling problems were the principal difficulty in achieving laser action on the K Ar/K2 system. Of the four molecular systems and pumping techniques explored, the capillary discharge pumped K Ar/K2 system appears to be the most likely candidate for demonstrating continuous wave excimer laser action primarily because of its predicted lower pumping threshold and a demonstrated discharge stability advantage
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Seasonal changes in the transport of pollutants into the Arctic troposphere-model study
Hidden assumptions in the derivation of the Theorem of Bell
John Bell's inequalities have already been considered by Boole in 1862. Boole
established a one-to-one correspondence between experimental outcomes and
mathematical abstractions of his probability theory. His abstractions are
two-valued functions that permit the logical operations AND, OR and NOT and are
the elements of an algebra. Violation of the inequalities indicated to Boole an
inconsistency of definition of the abstractions and/or the necessity to revise
the algebra. It is demonstrated in this paper, that a violation of Bell's
inequality by Einstein-Podolsky-Rosen type of experiments can be explained by
Boole's ideas. Violations of Bell's inequality also call for a revision of the
mathematical abstractions and corresponding algebra. It will be shown that this
particular view of Bell's inequalities points toward an incompleteness of
quantum mechanics, rather than to any superluminal propagation or influences at
a distance
Theory of I-V Characteristics of Magnetic Josephson Junctions
We analyze the electrical characteristics of a circuit consisting of a free
thin-film magnetic layer and source and drain electrodes that have opposite
magnetization orientations along the free magnet's two hard directions. We find
that when the circuit's current exceeds a critical value there is a sudden
resistance increase which can be large in relative terms if the currents to
source or drain are strongly spin polarized and the free magnet is thin. This
behavior can be partly understood in terms of a close analogy between the
magnetic circuit and a Josephson junction
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