Modeling ring current ion and electron dynamics and plasma instabilities during a high‐speed stream driven storm

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94593/1/jgra21840.pd

Optimized refractive surgery in keratoconus

Purpose: The aim of the study is to compare the refractive results after simultaneous TransPRK and Cross-linking procedure for treatment of keratoconus with optimized and non-optimized customized ablation profiles; to introduce the concept of optimization in keratoconus and discuss its clinical significance; to find predictive factors for better refractive outcomes in simultaneous combined procedures and to propose therapeutic algorithm.Methods: Syrius schimpflug aberrometer (Schwind) was used to create non-optimized custom and optimized custom ablation profiles in keratoconic corneas. TransPRK ablation was performed with Schwind Amaris Eximer Laser (500 Hz). Cross-linking was done with Avedro cross-linking suit. Analysis of preoperative and postoperative refraction, visual acuity, keratometric and aberometric data was done for both groups. Correlative analysis of the preoperative and postoperative variables was done with Pierson statistical analysis.Results: 44 patients (70 eyes), age 19-67, 29 eyes with optimization, 41 eyes without optimization were followed for 18 months. A positive correlation was found between CCT and the amount of postoperative flattening in patients over 40 years of age. No correlation was found with Kavg.Conclusions: Long term results after simultaneous TransPRK + Cross linking show stability and safety. Optimization of refraction brings better refractive results compared to non-optimized procedure. It can be safely performed in thinner corneas and compensates for the hypermetropic shift generated by the cross-linking procedure

Application and testing of the L neural network with the self-consistent magnetic field model of RAM-SCB

Abstract We expanded our previous work on L neural networks that used empirical magnetic field models as the underlying models by applying and extending our technique to drift shells calculated from a physics-based magnetic field model. While empirical magnetic field models represent an average, statistical magnetospheric state, the RAM-SCB model, a first-principles magnetically self-consistent code, computes magnetic fields based on fundamental equations of plasma physics. Unlike the previous L neural networks that include McIlwain L and mirror point magnetic field as part of the inputs, the new L neural network only requires solar wind conditions and the Dst index, allowing for an easier preparation of input parameters. This new neural network is compared against those previously trained networks and validated by the tracing method in the International Radiation Belt Environment Modeling (IRBEM) library. The accuracy of all L neural networks with different underlying magnetic field models is evaluated by applying the electron phase space density (PSD)-matching technique derived from the Liouville\u27s theorem to the Van Allen Probes observations. Results indicate that the uncertainty in the predicted L is statistically (75%) below 0.7 with a median value mostly below 0.2 and the median absolute deviation around 0.15, regardless of the underlying magnetic field model. We found that such an uncertainty in the calculated L value can shift the peak location of electron phase space density (PSD) profile by 0.2 RE radially but with its shape nearly preserved. Key Points L* neural network based on RAM-SCB model is developed L* calculation accuracy is estimated by PSD matching using RBSP data L* uncertainty causes a radial shift in the electron phase space density profile

The effects of dynamic ionospheric outflow on the ring current

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94583/1/jgra20739.pd

The two‐way relationship between ionospheric outflow and the ring current

It is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first‐principles‐based numerical models to test the dependence of ionospheric outflow on ring current‐driven region 2 field‐aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptive Tree Solar wind Roe‐type Upwind Scheme, BATS‐R‐US), a polar wind model (Polar Wind Outflow Model), and a bounce‐averaged kinetic ring current model (ring current atmosphere interaction model with self‐consistent magnetic field, RAM‐SCB). Initially, each code is two‐way coupled to all others except for RAM‐SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS‐R‐US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the noncoupled results. The additional outflow further energizes the ring current, establishing an ionosphere‐magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere‐magnetosphere‐ring current system.Key PointsRegion 2 field‐aligned currents drive additional ionospheric O+ outflowThis additional outflow feeds the ring current, creating a feedback systemIonospheric outflow is a tightly coupled piece of the M‐I systemPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112284/1/jgra51836.pd

IFMIF suitability for evaluation of fusion functional materials

The International FusionMaterials Irradiation Facility (IFMIF) is a future neutron source based on the D-Li stripping reaction, planned to test candidate fusionmaterials at relevant fusion irradiation conditions. During the design of IFMIF special attention was paid to the structural materials for the blanket and first wall, because they will be exposed to the most severe irradiation conditions in a fusion reactor. Also the irradiation of candidate materials for solid breeder blankets is planned in the IFMIF reference design. This paper focuses on the assessment of the suitability of IFMIF irradiation conditions for testing functionalmaterials to be used in liquid blankets and diagnostics systems, since they are been also considered within IFMIF objectives. The study has been based on the analysis and comparison of the main expected irradiation parameters in IFMIF and DEMO reactor

REVISING THE THEORY OF SOCIALLY INCLUSIVE SYSTEMS ENGINEERING SOCIAL IMPACT CONSIDERATIONS IN DISTRIBUTED ASSISTIVE SYSTEMS FOR THE LEARNING DISABLED

the relationship between humans and advanced technology can be viewed as a network of interests of technical and non-technical agents. Drawing upon instrumental realist approaches as set out in agent network theory the paper describes a project currently underway in Ireland and Bulgaria which delivers comprehensive, assistive systems for people with learning disabilities. These systems address many of the difficulties associated with current assistive technology (AT) programmes, problems typically associated with the narrow focus of AT upon technology solutions. Whilst limited, it delivers a sound ethical basis for technology-centred programmes, and new trajectories for engineering research

An improved empirical model of electron and ion fluxes at geosynchronous orbit based on upstream solar wind conditions

A new empirical model of the electron fluxes and ion fluxes at geosynchronous orbit (GEO) is introduced, based on observations by Los Alamos National Laboratory (LANL) satellites. The model provides flux predictions in the energy range ~1 eV to ~40 keV, as a function of local time, energy, and the strength of the solar wind electric field (the negative product of the solar wind speed and the z component of the magnetic field). Given appropriate upstream solar wind measurements, the model provides a forecast of the fluxes at GEO with a ~1 h lead time. Model predictions are tested against in‐sample observations from LANL satellites and also against out‐of‐sample observations from the Compact Environmental Anomaly Sensor II detector on the AMC‐12 satellite. The model does not reproduce all structure seen in the observations. However, for the intervals studied here (quiet and storm times) the normalized root‐mean‐square deviation < ~0.3. It is intended that the model will improve forecasting of the spacecraft environment at GEO and also provide improved boundary/input conditions for physical models of the magnetosphere.Key PointsNew model of electron and ion fluxes at GEO (driven by ‐vBz) provides a ~1 h forecast of fluxes in the energy range ~1 eV to ~40 keVThe main benefit from the new model is the ability to predict the fluxes at GEO in advanceForecasts are a good match to observations during quiet times and storm timesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134149/1/swe20339_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134149/2/swe20339.pd

Energy Content of the Stormtime Ring Current

Given the important role the ring current plays in magnetospheric energetics, it is essential to understand its strength and evolution in disturbed times. There are currently three main methods for deducing the strength of the ring current: measuring ground magnetic perturbations, measuring high-altitude magnetic perturbations, or directly measuring ring current particles. The use of ground magnetometers is the most convenient, and many use the ground magnetometer-derived Dst index as a proxy for the ring current. Recent work suggests, however, that a substantial portion of Dst may not be caused only by the ring current but also by local induction effects or other magnetospheric currents, so simply using the Dst index may yield inaccurate results. This study uses direct particle measurements to calculate the strength of the ring current and compares this to the measured Dst values. We investigate several magnetic storm intervals, using the Polar Charge and Mass Magnetospheric Ion Composition Experiment (CAMMICE) to measure ring current ions. We then use the Dessler-Parker-Sckopke relation to compare this to the measured Dst. This analysis is used both to understand the general behavior of the ring current compared to Dst as well as to compare the usefulness of the Dst proxy for different types of storms. Ring current ions are shown in this analysis to contribute, on average, half of the Dst depression, with a large variation among individual events

Self‐consistent inner magnetosphere simulation driven by a global MHD model

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95243/1/jgra20909.pd