Wear Testing and Analysis of Ion Engine Discharge Cathode Keeper

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77116/1/AIAA-4441-635.pd

Application of extended numerical approximation of fractional order derivatives in adaptive control

In a novel branch of soft computing developed in the past few years the desired and the expected response of the system is mapped to each other. In the case of mechanical systems the compared values are the second time-derivatives of the joint coordinates for the estimation of which certain finite element approximations are used in a digital control. This may result in a kind of noise and estimation sensivity. In the present paper these integer order derivatives are replaced by discrete numerical estimations of fractional order derivatives near the order of two to make the control more stable and accurate. For this purpose Caputo's form is considered the numerical approximation of which can be extended over the limits of the original definition. In this view differentiation seems to be an operation with some time-invariant Green function. Simulation results obtaind for the adaptive control of an inaccurately modeled electromechanical system containing an unmodeled and undriven internal degree of freedom illustrate that the quality of the control can be improved if the order of derivation in the signals used for comparison are increased form 2 to 2.25.info:eu-repo/semantics/publishedVersio

Hippocampal Network Dynamics during Rearing Episodes

Animals build a model of their surroundings on the basis of information gathered during exploration. Rearing on the hindlimbs changes the vantage point of the animal, increasing the sampled area of the environment. This environmental knowledge is suggested to be integrated into a cognitive map stored by the hippocampus. Previous studies have found that damage to the hippocampus impairs rearing. Here, we characterize the operational state of the hippocampus during rearing episodes. We observe an increase of theta frequency paralleled by a sink in the dentate gyrus and a prominent theta-modulated fast gamma transient in the middle molecular layer. On the descending phase of rearing, a decrease of theta power is detected. Place cells stop firing during rearing, while a different subset of putative pyramidal cells is activated. Our results suggest that the hippocampus switches to a different operational state during rearing, possibly to update spatial representation with information from distant sources

Measurement of 30-Centimeter Ion Thruster Discharge Cathode Erosion

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76209/1/AIAA-22982-649.pd

Particle Simulation of Plume Flows from an Anode-Layer Hall Thruster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76848/1/AIAA-28384-370.pd

A rescued dataset of sub-daily meteorological observations for Europe and the southern Mediterranean region, 1877–2012

Sub-daily meteorological observations are needed for input to and assessment of high-resolution reanalysis products to improve understanding of weather and climate variability. While there are millions of such weather observations that have been collected by various organisations, many are yet to be transcribed into a useable format. Under the auspices of the Uncertainties in Ensembles of Regional ReAnalyses (UERRA) project, we describe the compilation and development of a digital dataset of 8.8 million meteorological observations of essential climate variables (ECVs) rescued across the European and southern Mediterranean region. By presenting the entire chain of data preparation, from the identification of regions lacking in digitised sub-daily data and the location of original sources, through the digitisation of the observations to the quality control procedures applied, we provide a rescued dataset that is as traceable as possible for use by the research community. Data from 127 stations and of 15 climate variables in the northern African and European sectors have been prepared for the period 1877 to 2012. Quality control of the data using a two-step semi-automatic statistical approach identified 3.5 % of observations that required correction or removal, on par with previous data rescue efforts. In addition to providing a new sub-daily meteorological dataset for the research community, our experience in the development of this sub-daily dataset gives us an opportunity to share some suggestions for future data rescue projects. All versions of the dataset, from the raw digitised data to data that have been quality controlled and converted to standard units, are available on PANGAEA: https://doi.org/10.1594/PANGAEA.886511 (Ashcroft et al., 2018)

Homogenization of tropospheric data: evaluating the algorithms under the presence of autoregressive process

Presentación realizada en: IX Hotine-Marussi Symposium celebrado en Roma del 18 al 22 de junio de 2018.This research was supported by the Polish National Science Centre, grant No. UMO-2016/21/B/ST10/02353

Relationship between weather conditions and admissions for ischemic stroke and subarachnoid hemorrhage

AIM: To assess impacts of different weather conditions on hospitalizations of patients with ischemic strokes and subarachnoid hemorrhages (SAH) in South Florida. METHODS: Diagnostic data of patients with spontaneous SAH and strokes were recorded between June 2010 and July 2013. Daily synchronous forecast charts were collected from the National Weather Service and the whole data were matched prospectively. The incidence rate ratio (IRR) was calculated. RESULTS: Increased incidence rate of ischemic stroke was consistent with the daily lowest and highest air pressure (IRR 1.03, P=0.128 and IRR 0.98, P=0.380, respectively), highest air temperature (IRR 0.99, P=0.375), and presence of hurricanes or storms (IRR 0.65, P=0.054). Increased incidence of SAH cases was consistent with daily lowest and highest air pressure (IRR 0.87, P<0.001 and IRR 1.08, P=0.019, respectively) and highest air temperature (IRR 0.98, P<0.001). Presence of hurricanes and/or tropical storms did not influence the frequency of SAH. We found no relationship between the presence of fronts and the admissions for ischemic stroke or SAH. CONCLUSION: Higher number of ischemic stroke and SAH cases can be expected with the daily lowest and highest air pressure, highest air temperature. Presence of hurricanes or tropical storms increased the risk of ischemic stroke but not the SAH. These findings can help to develop preventive health plans for cerebrovascular diseases