19,016 research outputs found
ALSEP termination report
The Apollo Lunar Surface Experiments Package (ALSEP) final report was prepared when support operations were terminated September 30, 1977, and NASA discontinued the receiving and processing of scientific data transmitted from equipment deployed on the lunar surface. The ALSEP experiments (Apollo 11 to Apollo 17) are described and pertinent operational history is given for each experiment. The ALSEP data processing and distribution are described together with an extensive discussion on archiving. Engineering closeout tests and results are given, and the status and configuration of the experiments at termination are documented. Significant science findings are summarized by selected investigators. Significant operational data and recommendations are also included
Insight into Resonant Activation in Discrete Systems
The resonant activation phenomenon (RAP) in a discrete system is studied
using the master equation formalism. We show that the RAP corresponds to a
non-monotonic behavior of the frequency dependent first passage time
probability density function (pdf). An analytical expression for the resonant
frequency is introduced, which, together with numerical results, helps
understand the RAP behavior in the space spanned by the transition rates for
the case of reflecting and absorbing boundary conditions. The limited range of
system parameters for which the RAP occurs is discussed. We show that a minimum
and a maximum in the mean first passage time (MFPT) can be obtained when both
boundaries are absorbing. Relationships to some biological systems are
suggested.Comment: 5 pages, 5 figures, Phys. Rev. E., in pres
Cedar River at Cedar Rapids, Iowa
For thirty-seven years we have noted with regret the gradual increase in the pollution of our river, in fact the increase has been quite rapid during recent years. During that time the inhabitants on the banks have increased three-fold while the amount of pollution that is put into the river has increased probably three-thousand-fold. A third of a century ago the Chlorine as Chlorides was three parts per million, the normal amount for unpolluted water in this region; now it is ten. A half a century ago when the Cedar Rapids water works were first built, raw water was put into the mains and for twelve years used for drinking water by a large per cent of the inhabitants
Case-control study of arsenic in drinking water and lung cancer in California and Nevada.
Millions of people are exposed to arsenic in drinking water, which at high concentrations is known to cause lung cancer in humans. At lower concentrations, the risks are unknown. We enrolled 196 lung cancer cases and 359 controls matched on age and gender from western Nevada and Kings County, California in 2002-2005. After adjusting for age, sex, education, smoking and occupational exposures, odds ratios for arsenic concentrations ≥85 µg/L (median = 110 µg/L, mean = 173 µg/L, maximum = 1,460 µg/L) more than 40 years before enrollment were 1.39 (95% CI = 0.55-3.53) in all subjects and 1.61 (95% CI = 0.59-4.38) in smokers. Although odds ratios were greater than 1.0, these increases may have been due to chance given the small number of subjects exposed more than 40 years before enrollment. This study, designed before research in Chile suggested arsenic-related cancer latencies of 40 years or more, illustrates the enormous sample sizes needed to identify arsenic-related health effects in low-exposure countries with mobile populations like the U.S. Nonetheless, our findings suggest that concentrations near 100 µg/L are not associated with markedly high relative risks
Inversion of the Diffraction Pattern from an Inhomogeneously Strained Crystal using an Iterative Algorithm
The displacement field in highly non uniformly strained crystals is obtained
by addition of constraints to an iterative phase retrieval algorithm. These
constraints include direct space density uniformity and also constraints to the
sign and derivatives of the different components of the displacement field.
This algorithm is applied to an experimental reciprocal space map measured
using high resolution X-ray diffraction from an array of silicon lines and the
obtained component of the displacement field is in very good agreement with the
one calculated using a finite element model.Comment: 5 pages, 4 figure
A finite element based formulation for sensitivity studies of piezoelectric systems
Sensitivity Analysis is a branch of numerical analysis which aims to quantify the affects that variability in the parameters of a numerical model have on the model output. A finite element based sensitivity analysis formulation for piezoelectric media is developed here and implemented to simulate the operational and sensitivity characteristics of a piezoelectric based distributed mode actuator (DMA). The work acts as a starting point for robustness analysis in the DMA technology
Book Reviews
Stace: Chancery Forms and Precedents. Annotated with Reference to the Practice in Michigan.; Tiffany: Handbook of the Law of Sales, (2nd ed., rev.); Taylor: The Science of Jurisprudence. A Treatise in which the Growth of Positive Law is Unfolded by the Historical Method and its Elements Classified and Defined by the Analytical
Multi-objective evolutionary–fuzzy augmented flight control for an F16 aircraft
In this article, the multi-objective design of a fuzzy logic augmented flight controller for a high performance fighter jet (the Lockheed-Martin F16) is described. A fuzzy logic controller is designed and its membership functions tuned by genetic algorithms in order to design a roll, pitch, and yaw flight controller with enhanced manoeuverability which still retains safety critical operation when combined with a standard inner-loop stabilizing controller. The controller is assessed in terms of pilot effort and thus reduction of pilot fatigue. The controller is incorporated into a six degree of freedom motion base real-time flight simulator, and flight tested by a qualified pilot instructor
A unified evaluation of iterative projection algorithms for phase retrieval
Iterative projection algorithms are successfully being used as a substitute
of lenses to recombine, numerically rather than optically, light scattered by
illuminated objects. Images obtained computationally allow aberration-free
diffraction-limited imaging and the possibility of using radiation for which no
lenses exist. The challenge of this imaging technique is transfered from the
lenses to the algorithms. We evaluate these new computational ``instruments''
developed for the phase retrieval problem, and discuss acceleration strategies.Comment: 12 pages, 9 figures, revte
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