14,850 research outputs found
Noncontact torque measurement using stroboscopic techniques
Noncontact torquemeter measures torsional deflection of rotating shaft and results are viewed on vernier scale. Magnitude of torque must be calculated from measured deflection. Device has no electric connections with the rotating member and is easy to use
The Filical Flora of Minnesota
I have the pleasure of reporting the following list of Ferns, with accompanying specimens, as observed by Miss E. W. Cathcart, of St. Paul. There are 30 species and 3 varieties
Investigation of the Damping of Liquids in Right-Circular Cylindrical Tanks, Including the Effects of a Time-Variant Liquid Depth
An experimental investigation was conducted to determine the effects of several basic variables upon the damping of the fundamental antisymmetric mode of liquids in right-circular cylindrical tanks without baffles. The variables examined include liquid depth, efflux rate, liquid amplitude, kinematic viscosity, and tank size. The data are presented in dimensionless form and compared with available theory. For the range of variables examined, variations of efflux rate and liquid amplitude were found to have no significant effects on the liquid damping. The following theoretical relationship was found to be adequate for the prediction of the variation of damping with liquid depth, kinematic viscosity, and tank size: [for equation see full text] where v is the kinematic viscosity, R is the cylinder radius, g is the acceleration due to gravity, and h is the liquid depth. However, the constant K was experimentally found in this investigation to have the value 5.23, which is 50 percent higher than the theoretically predicted value
A "partitioned leaping" approach for multiscale modeling of chemical reaction dynamics
We present a novel multiscale simulation approach for modeling stochasticity
in chemical reaction networks. The approach seamlessly integrates
exact-stochastic and "leaping" methodologies into a single "partitioned
leaping" algorithmic framework. The technique correctly accounts for stochastic
noise at significantly reduced computational cost, requires the definition of
only three model-independent parameters and is particularly well-suited for
simulating systems containing widely disparate species populations. We present
the theoretical foundations of partitioned leaping, discuss various options for
its practical implementation and demonstrate the utility of the method via
illustrative examples.Comment: v4: 12 pages, 5 figures, final accepted version. Error found and
fixed in Appendi
A nonparametric point estimation technique using the m-out-of-n bootstrap
We investigate a method which can be used to improve an existing point estimator by a modification of the estimator and by using the m-out-of-n bootstrap. The estimation method used, known as bootstrap robust aggregating (or BRAGGing) in the literature, will be applied in general to the estimators that satisfy the smooth function model (for example, a mean, a variance, a ratio of means or variances, or a correlation coefficient), and then specifically to an estimator for the population mean. BRAGGing estimators based on both a naive and corrected version of them-out-of-n bootstrap will be considered. We conclude with proposed data-based choices of the resample size, m, as well as Monte-Carlo studies illustrating the performance of the estimators when estimating the population mean for various distributions
Investigation of a direction sensitive sapphire detector stack at the 5 GeV electron beam at DESY-II
Extremely radiation hard sensors are needed in particle physics experiments
to instrument the region near the beam pipe. Examples are beam halo and beam
loss monitors at the Large Hadron Collider, FLASH or XFEL. Currently artificial
diamond sensors are widely used. In this paper single crystal sapphire sensors
are considered as a promising alternative. Industrially grown sapphire wafers
are available in large sizes, are of low cost and, like diamond sensors, can be
operated without cooling. Here we present results of an irradiation study done
with sapphire sensors in a high intensity low energy electron beam. Then, a
multichannel direction-sensitive sapphire detector stack is described. It
comprises 8 sapphire plates of 1 cm^2 size and 525 micro m thickness,
metallized on both sides, and apposed to form a stack. Each second metal layer
is supplied with a bias voltage, and the layers in between are connected to
charge-sensitive preamplifiers. The performance of the detector was studied in
a 5 GeV electron beam. The charge collection efficiency measured as a function
of the bias voltage rises with the voltage, reaching about 10 % at 950 V. The
signal size obtained from electrons crossing the stack at this voltage is about
22000 e, where e is the unit charge.
The signal size is measured as a function of the hit position, showing
variations of up to 20 % in the direction perpendicular to the beam and to the
electric field. The measurement of the signal size as a function of the
coordinate parallel to the electric field confirms the prediction that mainly
electrons contribute to the signal. Also evidence for the presence of a
polarisation field was observed.Comment: 13 pages, 7 figures, 3 table
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