1,011 research outputs found
Exact Relativistic 'Antigravity' Propulsion
The Schwarzschild solution is used to find the exact relativistic motion of a
payload in the gravitational field of a mass moving with constant velocity. At
radial approach or recession speeds faster than 3^-1/2 times the speed of
light, even a small mass gravitationally repels a payload. At relativistic
speeds, a suitable mass can quickly propel a heavy payload from rest nearly to
the speed of light with negligible stresses on the payload.Comment: 4 pages, 3 figures, changed format only, attached 5 AVI files
(animated exact solutions of black holes incident on initially stationary
payloads
An Innovative Approach to Achieve Compositionality Efficiently using Multi-Version Object Based Transactional Systems
In the modern era of multicore processors, utilizing cores is a tedious job.
Synchronization and communication among processors involve high cost. Software
transaction memory systems (STMs) addresses this issues and provide better
concurrency in which programmer need not have to worry about consistency
issues. Another advantage of STMs is that they facilitate compositionality of
concurrent programs with great ease. Different concurrent operations that need
to be composed to form a single atomic unit is achieved by encapsulating them
in a single transaction. In this paper, we introduce a new STM system as
multi-version object based STM (MVOSTM) which is the combination of both of
these ideas for harnessing greater concurrency in STMs. As the name suggests
MVOSTM, works on a higher level and maintains multiple versions corresponding
to each key. We have developed MVOSTM with the unlimited number of versions
corresponding to each key. In addition to that, we have developed garbage
collection for MVOSTM (MVOSTM-GC) to delete unwanted versions corresponding to
the keys to reduce traversal overhead. MVOSTM provides greater concurrency
while reducing the number of aborts and it ensures compositionality by making
the transactions atomic. Here, we have used MVOSTM for the list and hash-table
data structure as list-MVOSTM and HT- MVOSTM. Experimental results of
list-MVOSTM outperform almost two to twenty fold speedup than existing
state-of-the-art list based STMs (Trans-list, Boosting-list, NOrec-list,
list-MVTO, and list-OSTM). HT-MVOSTM shows a significant performance gain of
almost two to nineteen times better than existing state-of-the-art hash-table
based STMs (ESTM, RWSTMs, HT-MVTO, and HT-OSTM). MVOSTM with list and
hash-table shows the least number of aborts among all the existing STM
algorithms. MVOSTM satisfies correctness-criteria as opacity.Comment: 35 pages, 23 figure
Dipole radio-frequency power from laser plasmas with no dipole moment
The radio-frequency power radiated from laser-target plasmas in a vacuum can
be orders of magnitude greater than expected from such sources that have a
negligible electric dipole moment. A model combining the Tidman-Stamper circuit
model of a laser-target plasma with the theory of radiation from currents
immersed in plasmas, however, predicts scaling of electric-dipole power
radiated from laser plasmas in agreement with experiments.Comment: 3 pages, 2 figures, as published in Applied Physics Letter
First generation of optical fiber phase reference distribution system for TESLA
This report describes the design of a phase stable Fiber Optic (FO) link for the TESLA technology based projects. The concept of this long optical link, with a feedback system suppressing long term drifts of the RF signal phase is described. Stability requirements are given and most important design issues affecting the system performance are discussed. The technical design issues of system components like laser transmitter and optical phase shifter are described in detail. Last sections depict the software developed for system control and experimental results obtained after system was assembled
Bouncing Neutrons and the Neutron Centrifuge
The recent observation of the quantum state of the neutron bouncing freely
under gravity allows some novel experiments. A method of purifying the ground
state is given, and possible applications to the measurement of the electric
dipole moment of the neutron and the short distance behaviour of gravity are
discussed.Comment: 7 pages, 7 figure
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