1,048 research outputs found
A robust subspace based approach to feedforward control of broadband disturbances on a six-degrees-of-freedom vibration isolation set-up
The contribution of this paper is twofold. First, the paper introduces a novel hybrid vibration isolation approach which uses a combination of passive and active vibration control techniques to provide additional design freedom. The approach can be used to meet higher design requirements with respect to vibration isolation. To illustrate the feasibility of the approach, a stiff hybrid sixdegrees-of-freedom vibration isolation set-up will be presented. The objective of the set-up is to investigate if the receiver structure can be isolated from the source structure by six hybrid vibration isolation mounts, such that disturbances induced by the source structure are isolated from the receiver structure. Vibration isolation is established by minimizing signals from six acceleration sensor outputs and by steering six piezo-electric actuator inputs. Our second contribution is that a state space based fixed gain H2 controller is designed, implemented and validated. Real-time broadband feedforward control results are presented (between 0 - 1 kHz) which show that an average reduction of 8.0 dB is achieved in the error sensor outputs in real-time
Neutrino mixing and CP violation from Dirac-Majorana bimaximal mixture and quark-lepton unification
We demonstrate that only two ansatz can produce the features of the neutrino
mixing angles. The first ansatz comes from the quark-lepton grand unification;
is satisfied for left-handed neutrinos, where
are the Dirac mass eigenstates and are the flavour
eigenstates. The second ansatz comes from the assumption; is satisfied between the Dirac mass eigenstates
and the light Majorana neutrino mass eigenstates , where
is the bimaximal mixing matrix. By these two ansatz, the
Maki-Nakagawa-Sakata matrix is given by . We find that in this model the novel relation is satisfied, where and are
solar and CHOOZ angle respectively. This "Solar-CHOOZ Complementarity" relation
indicates that only if the CHOOZ angle is sizable, the solar
angle can deviate from the maximal mixing. We also infer the CP
violation in neutrino oscillations. The leptonic Dirac CP phase
is predicted as , where are the CKM parameters in Wolfenstein parametrization. Furthermore, we
remark that the ratio of the Jarlskog CP violation factor for quarks and
leptons is important, because the large uncertainty on is cancelled out
in the ratio, .Comment: 9 pages, no figures; v2 references added, v3 references adde
The Feasibility of Enhacing Streamflow in the Sevier River Basin of Utah by Seeding Winter Mountain Clouds
The Bureau of Reclamation conducted a feasibility study of seeding winter mountain clouds as a possible means of enhancing the water supplies of the Sevier River Basin of Utah. A considerable body of pertinent meteorological observations from in or near the basin is examined. The evidence indicates that Utah winter mountain clouds often have more supercooled liquid water available than is naturally converted to snowfall. Thus, the needed raw material for cloud seeding to be effective is frequently available. Much of the excess liquid water has been found in the lowest kilometer or less over the mountain barriers, a region that can be seeded with properly located ground generators. This zone is too warm for silver iodide seeding during some storms and other agents, such as propane, should also be considered. Past operational and experimental seeding projects in the region are examined. There are suggestions from some analyses that seeding has produced about 10 percent more precipitation on a seasonal basis. However, other analyses have disputed these suggestions and it is concluded that the question of the effectiveness of current seeding practices is still an open one. It is recommended that a two phase demonstration program be conducted to place the emerging technology of winter cloud seeding on a firm scientific foundation. Physical experiments should be emphasized which document all key links in the chain of physical processes following seeding. Benefit-cost ratios for an operational seeding program are estimated with the caveat that a number of assumptions need further testing. However, if seeding could produce additional snowfall even approaching 10 percent per winter, the value of the additional water would likely exceed, and perhaps far exceed, the cost of seeding operations
Dynamics of chiral oscillations - A comparative analysis with spin-flipping
Chiral oscillation as well as spin flipping effects correspond to quantum
phenomena of fundamental importance in the context of particle physics and, in
particular, of neutrino physics. From the point of view of first quantized
theories, we are specifically interested in appointing the differences between
chirality and helicity by obtaining their dynamic equations for a fermionic
Dirac-type particle (neutrino). We also identify both effects when the
non-minimal coupling with an external (electro)magnetic field in the neutrino
interacting Lagrangian is taken into account. We demonstrate that, however,
there is no constraint between chiral oscillations, when it takes place in
vacuum, and the process of spin flipping related to the helicity quantum
number, which does not take place in vacuum. To conclude, we show that the
origin of chiral oscillations (in vacuum) can be interpreted as position very
rapid oscillation projections onto the longitudinal direction of momentum.Comment: 14 pages, no figure
The Noncommutative Standard Model and Forbidden Decays
In this contribution we discuss the Noncommutative Standard Model and the
associated Standard Model-forbidden decays that can possibly serve as an
experimental signature of space-time noncommutativity.Comment: 15 pages, 1 figure, Invited talk at 9th Adriatic Meeting and Central
European Symposia on Particle Physics and The Universe, Dubrovnik, Croatia,
4-14 Sep 200
Signature of sterile species in atmospheric neutrino data at neutrino telescopes
The MiniBooNE results have still not been able to comprehensively rule out
the oscillation interpretation of the LSND experiment. So far the so-called
short baseline experiments with energy in the MeV range and baseline of few
meters have been probing the existence of sterile neutrinos. We show how
signatures of these extra sterile states could be obtained in TeV energy range
atmospheric neutrinos travelling distances of thousands of kilometers.
Atmospheric neutrinos in the TeV range would be detected by the upcoming
neutrino telescopes. Of course vacuum oscillations of these neutrinos would be
very small. However, we show that resonant matter effects inside the Earth
could enhance these very tiny oscillations into near-maximal transitions, which
should be hard to miss. We show that imprint of sterile neutrinos could be
unambiguously obtained in this high energy atmospheric neutrino event sample.
Not only would neutrino telescopes tell the presence of sterile neutrinos, it
should also be possible for them to distinguish between the different possible
mass and mixing scenarios with additional sterile states.Comment: 26 pages, 11 figures, Version to appear in JHE
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