3,226 research outputs found
Inconsistency of QED in the Presence of Dirac Monopoles
A precise formulation of local gauge invariance in QED is presented,
which clearly shows that the gauge coupling associated with the unphysical
longitudinal photon field is non-observable and actually has an arbitrary
value. We then re-examine the Dirac quantization condition and find that its
derivation involves solely the unphysical longitudinal coupling. Hence an
inconsistency inevitably arises in the presence of Dirac monopoles and this can
be considered as a theoretical evidence against their existence. An
alternative, independent proof of this conclusion is also presented.Comment: Extended and combined version, refinements added; 20 LaTex pages,
Published in Z. Phys. C65, pp.175-18
Design and Analysis of an Air Filter Sensor for a Residential Heating and Cooling System
This is a design project of an air-filter sensor to be used in home heating and cooling system. The project includes conceptual design, analysis, implementation, tests and modifications. First, the air quality and power consumption between a clean air filter and a dirty air filter is studied. Then, a photo sensor circuit with an ultra high brightness LED emitter and a phototransistor receiver is used to detect dust particles. A red warning LED lights up when a specified amount of dust is collected on the filter and blocks the light beam between the emitter and the receiver. The emitter and receiver are mounted on a simple fixture and can be easily fitted on any air filter. In addition, the cost analysis shows that this design can significantly reduce the electricity bill if the filters are properly replaced
Implementation of a closed-loop structural control system using wireless sensor networks
Wireless sensor networks have rapidly matured in recent years to offer data acquisition capabilities on par with those of traditional tethered data acquisition systems. Entire structural monitoring systems assembled from wireless sensors have proven to be low cost, easy to install, and accurate. However, the functionality of wireless sensors can be further extended to include actuation capabilities. Wireless sensors capable of actuating a structure could serve as building blocks of future generations of structural control systems. In this study, a wireless sensor prototype capable of data acquisition, computational analysis and actuation is proposed for use in a real-time structural control system. The performance of a wireless control system is illustrated using a full-scale structure controlled by a semi-active magnetorheological (MR) damper and a network of wireless sensors. One wireless sensor designated as a controller automates the task of collecting state data, calculating control forces, and issuing commands to the MR damper, all in real time. Additional wireless sensors are installed to measure the acceleration and velocity response of each system degree of freedom. Base motion is applied to the structure to simulate seismic excitations while the wireless control system mitigates inter-storey drift response of the structure. An optimal linear quadratic regulation solution is formulated for embedment within the computational cores of the wireless sensors. Copyright © 2007 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/60230/1/214_ftp.pd
Long-lived neutral-kaon flux measurement for the KOTO experiment
The KOTO ( at Tokai) experiment aims to observe the CP-violating rare
decay by using a long-lived neutral-kaon
beam produced by the 30 GeV proton beam at the Japan Proton Accelerator
Research Complex. The flux is an essential parameter for the measurement
of the branching fraction. Three neutral decay modes, , , and were used to
measure the flux in the beam line in the 2013 KOTO engineering run. A
Monte Carlo simulation was used to estimate the detector acceptance for these
decays. Agreement was found between the simulation model and the experimental
data, and the remaining systematic uncertainty was estimated at the 1.4\%
level. The flux was measured as per protons on a
66-mm-long Au target.Comment: 27 pages, 16 figures. To be appeared in Progress of Theoretical and
Experimental Physic
Holographic Gauge Theory with Maxwell Magnetic Field
We first apply the transformation of mixing azimuthal with wrapped coordinate
to the 11D M-theory with a stack N M5-branes to find the spacetime of a stack
of N D4-branes with magnetic field in 10D IIA string theory, after the
Kaluza-Klein reduction. In the near-horizon limit the background becomes the
Melvin magnetic field deformed . Although the solution
represents the D-branes under the Melvin RR one-form we use a simple
observation to see that it also describes the solution of D-branes under the
Maxwell magnetic field. As the magnetic field we consider is the part of the
background itself we have presented an alternative to previous literature,
because our method does not require the assumption of negligible back reaction.
Next, we use the found solution to investigate the meson property through D4/D8
system (Sakai-Sugimoto model) and compare it with those studied by other
authors. Finally, we present a detailed analysis about the Wilson loop therein
and results show that the external Maxwell magnetic field will enhance the
quark-antiquark potential.Comment: Latex 14 pp, add fi
Measurement of Cosmic-ray Muons and Muon-induced Neutrons in the Aberdeen Tunnel Underground Laboratory
We have measured the muon flux and production rate of muon-induced neutrons
at a depth of 611 m water equivalent. Our apparatus comprises three layers of
crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray
muons and 760 L of gadolinium-doped liquid scintillator for producing and
detecting neutrons. The vertical muon intensity was measured to be cmssr. The yield of
muon-induced neutrons in the liquid scintillator was determined to be
neutrons/(gcm). A fit to the recently measured neutron
yields at different depths gave a mean muon energy dependence of for liquid-scintillator targets.Comment: 14 pages, 17 figures, 3 table
STEM Initiatives: Stimulating Students to Improve Science and Mathematics Achievement
The article focuses on how concepts in science, technology education, and mathematics show powerful relationships when it comes to student learning. Learning theorists believe that, through designed learning environments (contexts) and learning with hands-on projects, new knowledge can not only be learned, but learned in such a way that the knowledge can be transferred for other applications. Scholars in the applied sciences (school science, technology, and mathematics) believe that these subjects have transfer among themselves and that engineering activities can establish the contexts to learn these subjects, plus aid in the transfer of knowledge. This collaborative movement is referred to as STEM — integrating instruction in science, technology education, engineering, and mathematics. For more information on the national standards, conduct a web search for National Science Education Standards (1996), Standards for Technological Literacy: Content for the Study of Technology (2000/2002), and Principles and Standards for School Mathematics, (2000)
Search for the decay
We performed a search for the decay with the
E391a detector at KEK. In the data accumulated in 2005, no event was observed
in the signal region. Based on the assumption of
proceeding via parity-violation, we obtained the single event sensitivity to be
, and set an upper limit on the branching ratio to
be at the 90% confidence level. This is a factor of 3.2
improvement compared to the previous results. The results of proceeding via parity-conservation were also presented in this paper
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