42,774 research outputs found
The H1 Forward Track Detector at HERA II
In order to maintain efficient tracking in the forward region of H1 after the
luminosity upgrade of the HERA machine, the H1 Forward Track Detector was also
upgraded. While much of the original software and techniques used for the HERA
I phase could be reused, the software for pattern recognition was completely
rewritten. This, along with several other improvements in hit finding and
high-level track reconstruction, are described in detail together with a
summary of the performance of the detector.Comment: Minor revision requested by journal (JINST) edito
Aerodynamic data banks for Clark-Y, NACA 4-digit and NACA 16-series airfoil families
With the renewed interest in propellers as means of obtaining thrust and fuel efficiency in addition to the increased utilization of the computer, a significant amount of progress was made in the development of theoretical models to predict the performance of propeller systems. Inherent in the majority of the theoretical performance models to date is the need for airfoil data banks which provide lift, drag, and moment coefficient values as a function of Mach number, angle-of-attack, maximum thickness to chord ratio, and Reynolds number. Realizing the need for such data, a study was initiated to provide airfoil data banks for three commonly used airfoil families in propeller design and analysis. The families chosen consisted of the Clark-Y, NACA 16 series, and NACA 4 digit series airfoils. The various component of each computer code, the source of the data used to create the airfoil data bank, the limitations of each data bank, program listing, and a sample case with its associated input-output are described. Each airfoil data bank computer code was written to be used on the Amdahl Computer system, which is IBM compatible and uses Fortran
An experimental and theoretical investigation of deposition patterns from an agricultural airplane
A flight test program has been conducted with a representative agricultural airplane to provide data for validating a computer program model which predicts aerially applied particle deposition. Test procedures and the data from this test are presented and discussed. The computer program features are summarized, and comparisons of predicted and measured particle deposition are presented. Applications of the computer program for spray pattern improvement are illustrated
X-Ray Diffraction and Reflectance Spectroscopy of Murchison Powders (CM2) After Thermal Analysis Under Reducing Conditions to Final Temperatures Between 300 and 1300c
The asteroids Ryugu and Bennu have spectral characteristics in common with CI/CM type carbonaceous chondrites and are target bodies for JAXAs Hayabusa2 and NASAs OSIRIS-Rex missions, respectively. Analog studies, based primarily on the Murchison CM2 chondrite, provide a pathway to separate spectral properties resulting space weathering from those inherent to parent-body, mineralogy, chemistry, and processes. Ryugu shares spectral properties with thermally metamorphosed and partly dehydrated CI/CM chondrites. We have undertaken a multidisciplinary study of the thermal decomposition of Murchison powder samples as an analog to metamorphic process that may have occurred on Ryugu. Bulk analyses include thermal And evolved gas analysis, X-ray diffraction (XRD), and VIS-NIR and Mssbauer spectroscopy; micro- to nanoscale analyses included scanning and transmission electron microscopy and electron probe micro analysisWe report here XRD and VIS-NIR analyses of pre- and post-heated Murchison powders, and in a companion paper report results from multiple electron beam techniques
Transition to turbulence in particulate pipe flow
We investigate experimentally the influence of suspended particles on the
transition to turbulence. The particles are monodisperse and neutrally-buoyant
with the liquid. The role of the particles on the transition depends both upon
the pipe to particle diameter ratios and the concentration. For large
pipe-to-particle diameter ratios the transition is delayed while it is lowered
for small ratios. A scaling is proposed to collapse the departure from the
critical Reynolds number for pure fluid as a function of concentration into a
single master curve.Comment: 4 pages, 4 figure
High-resolution Observations of OH(1720 MHz) Masers Toward the Galactic Center
High-resolution VLA observations of 1720 MHz OH maser emission from Sgr A
East and the circumnuclear disk with spatial and spectral resolutions of
2\dasec5 1\dasec3 and 0.27 \kms are reported. This follow-up
observational study focuses on the recent discovery of a number of such OH
maser features and their intense circularly polarized maser lines detected
toward these Galactic center sources. The 1720 MHz maser line of OH arises from
collisionally excited gas behind a C-type shock and is an important diagnostic
of the interaction process that may occur between molecular clouds and
associated X-ray emitting shell-type supernova remnants. The present
observations have confirmed that the observed Stokes signal is due to
Zeeman splitting and that the OH masers are angularly broadened by the
scattering medium toward the Galactic center. The scale length of the magnetic
field fluctuations in the scattering medium toward the Galactic center is
estimated to be greater than 0.1-0.2 pc using the correlation of the position
angles of the scatter-broadened maser spots. In addition, the kinematics of the
maser spots associated with Sgr A East are used to place a 5 pc displacement
between this extended radio structure and the Galactic center.Comment: 13 pages, 2 Tables and 2 figures, to be published in Ap
- …