Anomaly of the geomagnetic Sq variation in Japan: effect from 3-D subterranean structure or the ocean effect?

Many years ago Rikitake et al. described the anomalous behaviour of the vertical component Z of the geomagnetic solar quiet (Sq) daily variation field at observatories in central and northern Japan - namely about 2 hr shift of the local noontime peak towards morning hours. They suggested that this anomaly is associated with the anomalous distribution of electrical conductivity in the mantle beneath central Japan. Although a few works have been done to confirm or argue this explanation, no clear answer has been obtained so far. The goal of this work is to understand the nature of this anomaly using our 3-D forward solution. The conductivity model of the Earth includes oceans of laterally variable conductance and conducting mantle either spherically symmetric or 3-D underneath. Data from six Japanese observatories at four seasons for two different years of the solar cycle are analysed. As an inducing ionospheric (Sq) current system, we use those provided by the Comprehensive Model (CM4) of Sabaka et al. Our analysis clearly demonstrates that 3-D induction in the ocean is responsible for the anomalous behaviour of Z daily variations in this region. We also show that the effects from a suite of 3-D mantle models that include mantle wedge and subducting slab are minor compared with the ocean effec

Prediction and control of drop formation modes in microfluidic generation of double emulsions by single-step emulsification

Hypothesis Predicting formation mode of double emulsion drops in microfluidic emulsification is crucial for controlling the drop size and morphology. Experiments and modelling A three-phase Volume of Fluid-Continuum Surface Force (VOF–CSF) model was developed, validated with analytical solutions, and used to investigate drop formation in different regimes. Experimental investigations were done using a glue-free demountable glass capillary device with a true axisymmetric geometry, capable of readjusting the distance between the two inner capillaries during operation. Findings A non-dimensional parameter (ζ) for prediction of double emulsion formation mode as a function of the capillary numbers of all fluids and device geometry was developed and its critical values were determined using simulation and experimental data. At logζ > 5.7, drops were formed in dripping mode; the widening jetting occurred at 5 < logζ < 5.7; while the narrowing jetting was observed at logζ < 5. The ζ criterion was correlated with the ratio of the break-up length to drop diameter. The transition from widening to narrowing jetting was achieved by increasing the outer fluid flow rate at the high capillary number of the inner fluid. The drop size was reduced by reducing the distance between the two inner capillaries and the minimum drop size was achieved when the distance between the capillaries was zero

<i style="">In-Situ</i> Monitoring of Phase Transition and Microstructure Evolution in Ni-Based Superalloys by Electrical Resistivity:Direct Comparison With Differential Scanning Calorimetry and Application to Case Studies

In this study, resistivity measurements are made during continuous heating and cooling on four different Ni-based superalloys of different grain structures and with different phases (i.e., γ′ and carbide). The results are directly compared with differential scanning calorimetry (DSC) profiles to identify the material’s resistivity response. The resistivity measurements have been performed using an electro-thermal mechanical testing (ETMT) system having a capability of heating and cooling a sample at a rate of up to 100 K/s by Joule heating, which is not possible with standard heating methods used in previous in-situ microstructure analysis approaches. By comparing different precipitate variations and thermal histories, γ′ volume fraction and precipitate number density are found to be the most important factors determining the resistivity of the materials. In-situ resistivity measurement was applied to several case studies to show that it can provide microstructural information in complex high temperature experiments.<br/

<i style="">In-Situ</i> Monitoring of Phase Transition and Microstructure Evolution in Ni-Based Superalloys by Electrical Resistivity:Direct Comparison With Differential Scanning Calorimetry and Application to Case Studies

In this study, resistivity measurements are made during continuous heating and cooling on four different Ni-based superalloys of different grain structures and with different phases (i.e., γ′ and carbide). The results are directly compared with differential scanning calorimetry (DSC) profiles to identify the material’s resistivity response. The resistivity measurements have been performed using an electro-thermal mechanical testing (ETMT) system having a capability of heating and cooling a sample at a rate of up to 100 K/s by Joule heating, which is not possible with standard heating methods used in previous in-situ microstructure analysis approaches. By comparing different precipitate variations and thermal histories, γ′ volume fraction and precipitate number density are found to be the most important factors determining the resistivity of the materials. In-situ resistivity measurement was applied to several case studies to show that it can provide microstructural information in complex high temperature experiments.<br/

Droplet Breakup in Flow Past an Obstacle: A Capillary Instability Due to Permeability Variations

In multiphase flow in confined geometries an elementary event concerns the interaction of a droplet with an obstacle. As a model of this configuration we study the collision of a droplet with a circular post that spans a significant fraction of the cross-section of a microfluidic channel. We demonstrate that there exist conditions for which a drop moves completely around the obstacle without breaking, while for the same geometry but higher speeds the drop breaks. Therefore, we identify a critical value of the capillary number above which a drop will break. We explain the results with a one-dimensional model characterizing the flow in the narrow gaps on either side of the obstacle, which identifies a surface-tension–driven instability associated with a variation in the permeability in the flow direction. The model captures the major features of the experimental observations.Harvard University (MRSEC (DMR-0820484))Schlumberger-Doll Research Cente

Evolution of the current system during solar wind pressure pulses based on aurora and magnetometer observations

Additional file 2: Figure S2. Same as Additional file 1 but for the July 14, 2012, event

A Comparative Study of High Temperature Tensile and Creep Testing Between Standard and Miniature Specimens:Applicability and Limits

This study concerns the quasi-static and time-dependent mechanical behavior obtained via the miniaturized electro-thermal mechanical testing (ETMT) approach for single crystal (SX) and conventional cast Mar-M-247 superalloy. The experimental outcome was benchmarked against standardized testing procedures. It is found that tensile yielding behavior can be captured accurately by the ETMT approach up to 1100 ºC, provided the appropriate type of thermocouple (T/C) is chosen. Furthermore, creep rupture behavior is underestimated by the miniaturized set-up. High repeatability of the rupture time was obtained for the SX case, whereas a significant scatter was observed for the conventional cast case. The discrepancies are assessed in detail; discussion centers around analytical and practical considerations, such as temperature uncertainty due to parasitic voltage and the choice of T/C, microstructural change as a result of the Joule heating, representative gauge volume, and strain rate non-linearity. Consequently, the applicability and limits of the miniaturized approach are examined critically, and improvements were suggested where appropriate

Deformation Mechanisms Rationalisation to Design for Creep Resistance in Polycrystalline Ni-Based Superalloys

Creep strength in polycrystalline Ni-based superalloys is influenced by the formation of a rich variety of planar faults forming within the strengthening γ' phase. The lengthening and thickening rate of these faults – and therefore the creep rate – depends on an intriguing combination of dislocation interactions at the γ-γ' interface and diffusional processes of the alloying elements at the core of the fault tip. The effect of alloy composition on this process is not fully understood. In this work we use correlative high resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy to study the deformation faults in two different Ni-based superalloys with carefully designed ratios of disordering-to-ordering-promoting elements (Co-Cr against Nb-Ta-Ti). The results show that the additions of ordering-promoting elements reduce the diffusional processes required for the faults to lengthen and thicken thus reducing the creep rates found for the higher Nb-Ta-Ti alloy. These insights provide a path to follow in the design of improved grades of creep-resistant polycrystalline alloys beyond 700 C

F2SD: A dataset for end-to-end group detection algorithms

The lack of large-scale datasets has been impeding the advance of deep learning approaches to the problem of F-formation detection. Moreover, most research works on this problem rely on input sensor signals of object location and orientation rather than image signals. To address this, we develop a new, large-scale dataset of simulated images for F-formation detection, called F-formation Simulation Dataset (F2SD). F2SD contains nearly 60,000 images simulated from GTA-5, with bounding boxes and orientation information on images, making it useful for a wide variety of modelling approaches. It is also closer to practical scenarios, where three-dimensional location and orientation information are costly to record. It is challenging to construct such a large-scale simulated dataset while keeping it realistic. Furthermore, the available research utilizes conventional methods to detect groups. They do not detect groups directly from the image. In this work, we propose (1) a large-scale simulation dataset F2SD and a pipeline for F-formation simulation, (2) a first-ever end-to-end baseline model for the task, and experiments on our simulation dataset.Comment: Accepted at ICMV 202