161,655 research outputs found
IPS Observation System for Miyun 50m Radio Telescope and Its Acceptance Observation
Ground-based observation of Interplanetary Scintillation(IPS) is an important
approach of monitoring solar wind. A ground-based IPS observation system is
newly implemented on 50m radio telescope, Miyun station, National Astronomical
Observatories, Chinese Academy of Sciences(NAOC). This observation system is
constructed for purpose of observing the solar wind speed and scintillation
index by using the normalized cross-spectrum of simultaneous dual-frequency IPS
measurement. The system consists of a universal dual-frequency front-end and a
dual-channel multi-function back-end specially designed for IPS. After careful
calibration and testing, IPS observations on source 3C273B and 3C279 are
successfully carried out. The preliminary observation results show that this
newly developed observation system is capable of doing IPS observation.The
system sensitivity for IPS observation can reach over 0.3Jy in terms of IPS
polarization correlator with 4MHz bandwidth and 2s integration time.Comment: 8 pages, 7 figure
A simulation of the instrument pointing system for the Astro-1 mission
NASA has recently completed a shuttle-borne stellar ultraviolet astronomy mission known as Astro-1. A three axis instrument pointing system (IPS) was employed to accurately point the science instruments. In order to analyze the pointing control system and verify pointing performance, a simulation of the IPS was developed using the multibody dynamics software TREETOPS. The TREETOPS IPS simulation is capable of accurately modeling the multibody IPS system undergoing large angle, nonlinear motion. The simulation is documented and example cases are presented demonstrating disturbance rejection, fine pointing operations, and multiple target pointing and slewing of the IPS
Development of a coronal mass ejection arrival time forecasting system using interplanetary scintillation observations
Coronal mass ejections (CMEs) cause disturbances in the environment of the
Earth when they arrive at the Earth. However, the prediction of the arrival of
CMEs still remains a challenge. We have developed an interplanetary
scintillation (IPS) estimation system based on a global magnetohydrodynamic
(MHD) simulation of the inner heliosphere to predict the arrival time of CMEs.
In this system, the initial speed of a CME is roughly derived from white light
coronagraph observations. Then, the propagation of the CME is calculated by a
global MHD simulation. The IPS response is estimated by the three-dimensional
density distribution of the inner heliosphere derived from the MHD simulation.
The simulated IPS response is compared with the actual IPS observations made by
the Institute for Space-Earth Environmental Research, Nagoya University, and
shows good agreement with that observed. We demonstrated how the simulation
system works using a halo CME event generated by a X9.3 flare observed on
September 5, 2017. We find that the CME simulation that best estimates the IPS
observation can more accurately predict the time of arrival of the CME at the
Earth. These results suggest that the accuracy of the CME arrival time can be
improved if our current MHD simulations include IPS data.Comment: 39 pages, 6 figures, accepted for publication in Earth, Planets and
Spac
Equilibrium Sampling From Nonequilibrium Dynamics
We present some applications of an Interacting Particle System (IPS)
methodology to the field of Molecular Dynamics. This IPS method allows several
simulations of a switched random process to keep closer to equilibrium at each
time, thanks to a selection mechanism based on the relative virtual work
induced on the system. It is therefore an efficient improvement of usual
non-equilibrium simulations, which can be used to compute canonical averages,
free energy differences, and typical transitions paths
Actuator development for the Instrument Pointing System (IPS)
The mechanisms of the instrument pointing system (IPS) are described. Particular emphasis is placed on the actuators which are necessary for operating the IPS. The actuators are described as follows: (1) two linear actuators that clamp the gimbals down during ascent and descent; (2) two linear actuators that attach the payload to the IPS during the mission, and release it into the payload clamps; (3) one rotational actuator that opens and closes the payload clamps; and (4) three identical drive units that represent the three orthogonal gimbal axes and are the prime movers for pointing. Design features, manufacturing problems, test performance, and results are presented
EOS image data processing system definition study
The Image Processing System (IPS) requirements and configuration are defined for NASA-sponsored advanced technology Earth Observatory System (EOS). The scope included investigation and definition of IPS operational, functional, and product requirements considering overall system constraints and interfaces (sensor, etc.) The scope also included investigation of the technical feasibility and definition of a point design reflecting system requirements. The design phase required a survey of present and projected technology related to general and special-purpose processors, high-density digital tape recorders, and image recorders
Design and analysis of collision reduction algorithms for LED-based indoor positioning with simulation and experimental validation
In this paper, we develop a low complexity indoor positioning system (IPS) and design a lightweight, low-cost, and wearable receiver for it. The accuracy of proximity-based LED IPS has been improved using overlap between LED beams but LED packets in the overlap region are subject to collisions. In this paper, we design collision handling algorithms for the IPS that considers building and lighting infrastructures. Mathematical analyses of the proposed algorithms are done and models for the probability of collisions are developed. The models, which are verified using simulations, are used to calculate the time required for position update called positioning time. Analysis of the positioning time is done for single and multiple receivers systems and validated with experimental measurements. Results show positioning error as low as 56 cm with a positioning time of about 300 ms for slotted unsynchronized systems and 500 ms for unslotted unsynchronized systems which makes the developed system pragmatic and appropriate for human positioning
The Influence of Medicare Home Health Payment Incentives: Does Payer Source Matter?
During the late 1990s, an interim payment system (IPS) was instituted to constrain Medicare home health care expenditures. Previous research has largely focused on the implications of the IPS for Medicare patients, but our study broadens the analysis to consider patients with other payer sources. Using the National Home and Hospice Care Survey, we found similar effects of the IPS across payer types. Specifically, the IPS was associated with a decrease in access to care for the sickest patients, less agency assistance with activities of daily living, and shorter length-of-use. However, these changes did not translate into worse discharge outcomes.Medicare, health, incentives
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