2,961 research outputs found
Numerical analysis of the operation of a water cannon
This study was designed to investigate the operational process of a launcher for generation of high speed water projectiles, and it involved the optimization of the geometry of a launcher body. The objective of the optimization of the internal geometry was to increase the effective momentum of the projectile while the optimization of the external geometry resulted in the reduction of the mass of the launcher.
In the course of the optimization of the internal geometry the exit velocity variation was determined, and used to compute an effective projectile momentum, which actually affects a workpiece. In this research, it was assumed that the effective momentum is generated if the velocity of the impacting fluid exceeds the critical velocity. A cutoff factor was introduced in order to separate a part of projectile which generates an effective momentum. A numerical model of the process developed by G. Atanov was used to determine the exit water velocity while a C++ program was developed in order to determine the effective momentum of the projectile at various launcher geometries. The optimization involved the approximation of the internal launcher geometry by a combination of a cylinder (barrel) and two cones (nozzle), the length and diameters of which constituted the process. The near optimal values of these variables were determined and have shown that the optimization of the nozzle geometry enables an increase in the effective momentum of a projectile by 40%.
The second problem surveyed the effect of the variation of the external geometry of the water cannon on its weight. An array of the cannon geometries, which assured the sufficient strength of the construction, was investigated and a shape minimizing the mass of the device was found. The Atanov model was used to determine the pressure distribution within the water cannon, and the computation package Pro-MECHANICA was applied to determine the stresses in the cannon body. The external geometry was selected so that at each cross section the actual stresses, static, and dynamic did not exceed the critical stresses determined by the use of the von Mises criterion. The analysis was carried out at the external geometry of the existing cannon prototype and had shown that the geometry optimization enables a reduction of the cannon mass by 15 %.
The third part of the experiment was devoted to investigate water slug-target interaction. It was carried out through an assimilation of a demining and a concrete demolition processes with a high-speed water projectile. The experiment has shown the importance of stand-off distance with different types of targets
Thermo-dynamical measurements for ATLAS Inner Detector (evaporative cooling system)
During the construction, installation and initial operation of the Evaporative
Cooling System for the ATLAS Inner Detector SCT Barrel Sub-detector, some
performance characteristics were observed to be inconsistent with the original design
specifications, therefore the assumptions made in the ATLAS Inner Detector
TDR were revisited. The main concern arose because of unexpected pressure
drops in the piping system from the end of the detector structure to the distribution
racks. The author of this theses made a series of measurements of these
pressure drops and the thermal behavior of SCT-Barrel cooling Stave. Tests were
performed on the installed detector in the pit, and using a specially assembled
full scale replica in the SR1 laboratory at CERN. This test setup has been used
to perform extensive tests of the cooling performance of the system including
measurements of pressure drops in different parts of system, studies of the thermal
profile along the stave pipe for different running conditions / parameters and
coolant flow measurements in the system. The pressure drops in the system and
the associated temperatures in the barrel cooling loops have been studied as a
function of the system variables, for example; input liquid pressure, vapour back
pressure, module power load and input liquid temperature. Measurements were
performed with 10, 11, 12, 13 barabs inlet liquid pressure in system, 1.2, 1.6, 2.0,
2.5, 3.0, 4.0, 5.0, 6.0 barabs vapour back pressure in system, and 0 W, 3 W, 6 W,
9 W, 10.5W power applied per silicon module. The measurements clearly show
that the cooling system can not achieve the design evaporation temperature of -25C in every part of the detector (SCT Barrel loops) in case of 13 barabs nominal inlet liquid pressure, 1.2 barabs minimum possible back pressure and 6W nominal
power per SCT Barrel silicon module and especially at the end of the ATLAS ID
operation period when modules will work on full power of 10.5 W. This will lead
to the problem of thermal run-away of the ATLAS SCT, especially near the end
of the operational period after significant radiation exposure has occurred. The
LHC luminosity profile, depletion voltage and leakage current values and the total
power dissipated from the modules were revised. Thermal runaway limits for the
ATLAS SCT sub-detector were also revised. Results show that coolants evaporation
temperature necessary for the sub-detector's safe operation over the full
lifetime (10 years) is -15C with a safety factor of 2. Laboratory measurements
clearly show that the cooling system can not achieve even this necessary evaporation
temperature of -15C. It is now impossible to make mechanical modifications
to the cooling system, for example; changing the diameter of the cooling pipes, or
the thermal performance of the in-system heat exchanger or reducing the vapour
back pressure. It was therefore decided to investigate changes to the cooling
fluid and to test mixtures of Hexafluoroethane (R116) C2F6 and Octafluoropropane(R218) C3F8 at differing ratios instead of just pure C3F8 coolant presently used.
For this purpose, a new "blending" machine was assembled in the SR1 laboratory,
with a new device an "on-line acoustic flow meter and fluorocarbon coolant
mixture analyzer" (Sonar Analyzer) attached to it. The Machines were connected
to the already existing laboratory test station and new extensive tests were performed
to investigate different proportion of C3F8/C2F6 blends to find the mixture
ratio which resulted in the best operational performance as measured by: the
temperature distribution, pressure drops and
flow parameters over the system,
to ensure best cooling performance of SCT Barrel cooling loops for long term
ATLAS SCT operation. Measurements were performed with different percentage
of C2F6 (1%, 2%, 3%, 5%, 10%, 20%, 25%) coolant in the C3F8/C2F6 mixture,
for different power (0 W, 3 W, 6 W, 9 W, 10.5W) applied to dummy modules on the SCT cooling stave, with 13 barabs inlet liquid pressure and for different vapour back pressures (1.2, 1.6, 2.0, 2.5, 3.0 barabs) in the system.
Results prove that with 25% of C2F6 in the blend mixture, it is possible to
lower the evaporation temperature by ~10C in the case of nominal operation
parameters of the system. The ATLAS Inner Detector Evaporative Cooling System
can therefore reach the necessary evaporation temperature and therefore can
guarantee thermal stability of the SCT, even at the end of the operation period
A Combine On-Line Acoustic Flowmeter and Fluorocarbon Coolant Mixture Analyzer for The ATLAS Silicon Tracker
An upgrade to the ATLAS silicon tracker cooling control system may require a
change from C3F8 (octafluoro-propane) to a blend containing 10-30% of C2F6
(hexafluoro-ethane) to reduce the evaporation temperature and better protect
the silicon from cumulative radiation damage with increasing LHC luminosity.
Central to this upgrade is a new acoustic instrument for the real-time
measurement of the C3F8/C2F6 mixture ratio and flow. The instrument and its
Supervisory, Control and Data Acquisition (SCADA) software are described in
this paper. The instrument has demonstrated a resolution of 3.10-3 for
C3F8/C2F6 mixtures with ~20%C2F6, and flow resolution of 2% of full scale for
mass flows up to 30gs-1. In mixtures of widely-differing molecular weight (mw),
higher mixture precision is possible: a sensitivity of < 5.10-4 to leaks of
C3F8 into the ATLAS pixel detector nitrogen envelope (mw difference 160) has
been seen. The instrument has many potential applications, including the
analysis of mixtures of hydrocarbons, vapours for semi-conductor manufacture
and anaesthesia
Development of a custom on-line ultrasonic vapour analyzer/flowmeter for the ATLAS inner detector, with application to gaseous tracking and Cherenkov detectors
Precision sound velocity measurements can simultaneously determine binary gas
composition and flow. We have developed an analyzer with custom electronics,
currently in use in the ATLAS inner detector, with numerous potential
applications. The instrument has demonstrated ~0.3% mixture precision for
C3F8/C2F6 mixtures and < 10-4 resolution for N2/C3F8 mixtures. Moderate and
high flow versions of the instrument have demonstrated flow resolutions of +/-
2% F.S. for flows up to 250 l.min-1, and +/- 1.9% F.S. for linear flow
velocities up to 15 ms-1; the latter flow approaching that expected in the
vapour return of the thermosiphon fluorocarbon coolant recirculator being built
for the ATLAS silicon tracker.Comment: Paper submitted to TWEPP2012; Topical Workshop on Electronics for
Particle Physics, Oxford, UK, September 17-21, 2012. KEYWORDS: Sonar;
Saturated fluorocarbons; Flowmetry; Sound velocity, Gas mixture analysis. 8
pages, 7 figure
Implementation of ultrasonic sensing for high resolution measurement of binary gas mixture fractions
We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10−5 is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions
A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam
A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors
located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This
new SBN Program will deliver a rich and compelling physics opportunity,
including the ability to resolve a class of experimental anomalies in neutrino
physics and to perform the most sensitive search to date for sterile neutrinos
at the eV mass-scale through both appearance and disappearance oscillation
channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND
and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we
estimate that a search for muon neutrino to electron neutrino appearance can be
performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter
region. In this proposal for the SBN Program, we describe the physics analysis,
the conceptual design of the LAr1-ND detector, the design and refurbishment of
the T600 detector, the necessary infrastructure required to execute the
program, and a possible reconfiguration of the BNB target and horn system to
improve its performance for oscillation searches.Comment: 209 pages, 129 figure
Model-independent evidence for contributions to decays
The data sample of decays acquired with the
LHCb detector from 7 and 8~TeV collisions, corresponding to an integrated
luminosity of 3 fb, is inspected for the presence of or
contributions with minimal assumptions about
contributions. It is demonstrated at more than 9 standard deviations that
decays cannot be described with
contributions alone, and that contributions play a dominant role in
this incompatibility. These model-independent results support the previously
obtained model-dependent evidence for charmonium-pentaquark
states in the same data sample.Comment: 21 pages, 12 figures (including the supplemental section added at the
end
Study of decays to the final state and evidence for the decay
A study of decays is performed for the first time
using data corresponding to an integrated luminosity of 3.0
collected by the LHCb experiment in collisions at centre-of-mass energies
of and TeV. Evidence for the decay
is reported with a significance of 4.0 standard deviations, resulting in the
measurement of
to
be .
Here denotes a branching fraction while and
are the production cross-sections for and mesons.
An indication of weak annihilation is found for the region
, with a significance of
2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html,
link to supplemental material inserted in the reference
Measurement of the lifetime
Using a data set corresponding to an integrated luminosity of ,
collected by the LHCb experiment in collisions at centre-of-mass energies
of 7 and 8 TeV, the effective lifetime in the
decay mode, , is measured to be ps. Assuming
conservation, corresponds to the lifetime of the light
mass eigenstate. This is the first measurement of the effective
lifetime in this decay mode.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-017.htm
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