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Geomagnetically induced current (GIC) is known to be closely related to the rate of change of local horizontal magnetic field (dBx/dt); and their spectra can give better insight into the relationship. We study the spectral characteristics of GIC measured in Finland and dBx/dt measured 30 km away during the 17 March 2013 intense geomagnetic storm (SymHMin = -132 nT). Two bursts of large GIC (up to 32A) and dBx/dt occurred at ~ 16 UT and 18 UT during the storm main phase, though their values were generally small. For the first time, the Cross Wavelet Transform (XWT) and Wavelet Coherence (WTC) techniques are used to investigate the correlation and phase relationship of GIC and dBx/dt in time-frequency domain. Their WTC correlation is strong (over 0.9) over the entire storm period, indicating dBx/dt is the main factor causing GIC and dBx/dt leading GIC. Their XWT spectra show two enclosed periods (8–42 min and 2–42 min) in the high energy region corresponding to the two bursts of activity in GIC and dBx/dt. Moreover, we use continuous wavelet transform (CWT) and discrete wavelet transform (DWT) to analyze the spectral characteristics of GIC and dBx/dt. It is found that the CWT and DWT spectra of the two are very similar, especially in the low frequency characteristics, without continuous periodicity. Wavelet coefficients become large when GIC and dBx/dT are large; and the third-order coefficient, which corresponds to low-frequency part, best reflects the disturbance of GIC and dBx/dt.

Thederived parameters of the geomagnetic storms in Kyoto Dst and USGS Dst

This study is aimed at reducing NOx, Smoke, HC, CO emissions from single-cylinder, four-stroke, and water cooled diesel engine. The research engine is fueled with diesel and two blends of butanol a...

Aim: Haller’s cells are developmental variants of anterior ethmoidal sinus which are also known as infraorbital ethmoidal cells or orbito ethmoidal cells or maxilla ethmoidal cells. These anatomic variants of sinonasal regions pneumatize inferiorly and medial to the orbital floor and towards the inferior of maxillary sinus. Hence, the present study was to determine the prevalence of Haller's cells using CT PNS images. Objectives: The purpose of the study is to determine the prevalence of Haller’s cells according to age and gender, to evaluate the relationship between Haller’s cells and maxillary sinusitis and to correlate between Haller’s cells and ipsilateral orbital floor dehiscence. Methods: CT PNS images of 60 patients within the age group of 16-75 years were retrieved, screened by a radiologist and analyzed. The data collected were subjected to statistical analysis analyzed with statistical software package, SPSS version 16.0. and p value < 0.05 was considered to be statistically significant. Results: The prevalence of Haller's cells in the present study was found to be 48%. There was no statistically significant association between the presence of Haller cells with respect to age and gender. There was a significant association between Haller cells with maxillary sinusitis and orbital floor dehiscence. Conclusion: This study has attempted to find the prevalence of Haller’s cells which will be helpful for dentists in specifying the differential diagnosis for Oro facial pain and maxillary sinusitis.

This study focuses on the effect of particle size of Titanium oxide (TiO2) nanoparticle on the emissions characteristics of diesel engine fuelled with neat honge biodiesel (HBD100). Titanium oxide ...

This work examines the effect of butanol (higher alcohol) on the emission pattern of neat neem oil biodiesel (NBD100) fueled diesel engine. Single-cylinder, 4-stroke, research diesel engine was emp...

The first example of a polar cap arc producing clear amplitude and phase scintillations in the GPS L-band is presented using observations from an all-sky imager and a GPS receiver at Resolute Bay and the SuperDARN Inuvik radar. The polar cap arc moved quickly from the dusk-side to the midnight auroral oval at a speed of ~700 m/s, as revealed by all-sky 557.7 nm and 630.0 nm images. When it intersected the ray path of GPS signals, both amplitude and phase scintillations appeared, which is very different from previous results. Moreover, the scintillations were precisely determined through power spectral analysis. We propose that the strong total electron content (TEC) enhancement (~6 TECU) and flow shears in association with the polar cap arc were causing the scintillations. It provides instructive evidence for the existence of polar cap arc scintillations that may be harmful for satellite applications even through L-band signals.

This paper presents a review of the progress in the understanding of an additional layer in the low latitude ionosphere, the F3 layer. A brief introduction to the daytime equatorial electrodynamics required for understanding the formation of F3 layer and formation of the usual ionospheric regions and layers are also included for continuity. Numerous papers on various aspects of F3 layer and topside ledge (F3 layer in the topside ionosphere) were published by different research groups using observations and modelling. The first time observations and important new aspects are highlighted and areas for further studies are suggested in this review. The important new aspects include an automated procedure for identifying F3 layer, global map of F3 layer and its longitudinal wave structure, solar activity variation of F3 layer and its long term trend, F3 layer in TEC, F3 layer at sunrise and sunset hours, simultaneous observations of F3 layer and upward ExB drift velocity, simultaneous observations of F3 layer in conjugate summer and winter locations, rapid ascend of F3 layer during geomagnetic storms as an indicator of eastward prompt penetration electric field and mechanism of F4 layer. Main points are summarized at the end.

The present study analyzes the emission pattern of Decanol combined Jatropha biodiesel (JBD100) fueled diesel engine and compared with conventional diesel fuel (D100). Experiments were conducted in...

A brief review of the recent developments in the understanding of the equatorial plasma fountain (EPF) and equatorial ionization anomaly (EIA) under quiet and active conditions is presented. It is clarified that (1) the EPF is not upward ExB plasma drift at the equator followed by downward plasma diffusion, but it is field perpendicular ExB plasma drift and field-aligned plasma diffusion acting together all along the field lines at all altitudes and plasma flowing in the direction of the resultant. (2) The EIA is formed not from the accumulation of plasma at the crests but mainly from the removal of plasma from around the equator by the upward ExB drift with small accumulations when the crests are within approximately ±20° magnetic latitude. The accumulations reduce with increasing latitude and become zero by approximately ±25°. (3) An asymmetric neutral wind makes EPF and EIA asymmetric with stronger fountain and stronger crest usually occurring in opposite hemispheres especially at equinoxes when winter anomaly is absent. (4) During the early stages of daytime main phase of major geomagnetic storms, the plasma fountain becomes a super fountain and the EIA becomes strong not due to the eastward prompt penetration electric field (PPEF) alone but due to the combined effect of eastward PPEF and storm-time equatorward winds (SEW). (5) During the later stages of the storms when EIA gets inhibited a peak sometimes occurs around the equator not due to westward electric fields but mainly due to the convergence of plasma from both hemispheres due to SEW.

This article deals with the energy audit in the residential building in OMR, Chennai (latitude and longitude are: 13.067439, 80.237617), India. The present article aims to identify the inefficient ...

The exhaust manifold is used to collect and deliver waste toxic gases through a single pipe. During this process, the exhaust manifold suffers from the thermal stresses causes blowholes on the mani...

Following a brief history and progress of ionospheric research, this paper presents a brief review of the recent developments in the understanding of two major phenomena in low and mid latitude ionosphere—the equatorial ionization anomaly (EIA) and involved equatorial plasma fountain (EPF) and ionospheric irregularities. Unlike the easy-to-understand misinterpretations, the EPF involves field perpendicularE×B plasma drift and field-aligned plasma diffusion acting together and plasma flowing in the direction of the resultant at all points along the field lines at all altitudes. The EIA is formed mainly from the removal of plasma from around the equator by the upward E×B drift creating the trough and consequently the crests with small accumulation of plasma at the crests when the crests are within ~±20° magnetic latitudes and no accumulation when they are beyond ~±25° magnetic latitudes. The strong EIA under magnetically active conditions arises from the simultaneous impulsive action of eastward prompt penetration electric field and equatorward neutral wind. Intense ionospheric irregularities develop in the post-sunset bottom-side equatorial ionosphere when it rises to high altitudes, and evolve nonlinearly into the topside. Pre-reversal enhancement (PRE) of the vertical upward E×B drift and its fluctuations amplified during PRE provide the driving force and seed, with neutral wind and gravity waves being the primary sources. At low solar activity especially in summer when fast varying PRE is absent, the slow varying gravity waves including large scale waves (LSW) seem to act as both driver and seed for weak irregularities. At mid latitudes, the irregularities are weak and associated with medium scale traveling ionospheric disturbances (MSTIDs). A low latitude minimum in the occurrence of the irregularities at March equinox predicted by theoretical models is identified. The minimum occurs on the poleward side of the EIA crest and shifts equatorward from ~25° magnetic latitudes at high solar activity to below 17° at low solar activity.

A scheme is suggested and tested for forecasting severe space weather (SvSW) using solar wind velocity (V) and the north-south component (Bz) of the interplanetary magnetic field (IMF) measured using the ACE (Advanced Composition Explorer) satellite from 1998 to 2016. SvSW has caused all known electric power outages and telegraph system failures. Earlier SvSW events such as the Carrington event of 1859, Quebec event of 1989 and an event in 1958 are included with information from the literature. Dst storms are used as references to identify 89 major space weather events (DstMin ≤ -100 nT) in 1998-2016. The coincidence of high CME front (or CME shock) velocity ΔV (sudden increase in V over the background by over 275 km/s) and sufficiently large Bz southward at the time of the ΔV increase is associated with SvSW; and their product (ΔV x Bz) is found to exhibit a large negative spike at the speed increase. Such a product (ΔV x Bz) exceeding a threshold seems suitable for forecasting SvSW. However, the coincidence of high V (not containing ΔV) and large Bz southward does not correspond to SvSW, indicating the importance of the impulsive action of large Bz southward and high ΔV coming through when they coincide. The need for the coincidence is verified using the CRCM (Comprehensive Ring Current Model) model, that produces extreme Dst storms (

In this paper we carry out a comparative study of the daytime (7–18 LT) behavior of the near-equatorial ionospheric F region at the end of the long deep solar minimum (2009) with respect to that of the previous normal solar minimum (1995) in the Indian longitude sector using ionosonde observations of F layer parameters, radar observations of E × B drift, and the IRI-2012 (International Reference Ionosphere-2012) model. We investigate the F2 and F3 layer behaviors separately. The results reveal that the peak frequencies of the F layer (fpeak), F2 layer (foF2), and F3 layer (foF3) in 2009 are consistently lower than those in 1995. Maximum difference in fpeak/foF2/foF3 between 2009 and 1995 observations is found in the equinoxes followed by winter and summer. The annual mean, seasonal mean, and 10 day mean peak electron density (corresponding to fpeak) in 2009 were lower than those in 1995 by as much as 34%, 46%, and 65%, respectively. Solar rotation effect is less conspicuous in 2009 than in 1995, consistent with the solar rotation signature in F10.7. Observations also show considerable amount of equinoctial asymmetry in electron density, which is found to be closely linked with the corresponding asymmetry in the vertical E × B drift. Seasonal mean peak electron densities of the F layer (corresponding to fpeak) and the F2 layer (corresponding to foF2) observed during the deep solar minimum of 2009 were smaller than those corresponding to IRI-2012 model foF2 by as much as 45% and 50%, respectively, underlining the need to incorporate the data collected during the long deep minimum in the IRI model. The unusually weak ionosphere observed in 2009 is discussed in terms of the direct effect of the low solar EUV flux in 2009 as compared to 1995 and its indirect effects on ionospheric electric field, thermospheric composition (or O/N2 ratio), and thermospheric neutral winds.

Background: Forensic science, also known as Criminalistics is a field of science that uses science for investigation and its application in civil and criminal proceedings. One of the main challenges is to identify the dead during criminal and mass disaster investigations. Aim: The study aims to evaluate the morphometry of the orbital aperture and to verify its relationship with biological sex discrimination using three-dimensional Computed Tomography (3D CT). Study Design: This retrospective study involves 100 3D CT images of 50 males and 50 females (age 18-60 years). Materials and Methods: The exclusion criteria were congenital anomalies affecting the head and neck region, orbital fracture, systemic diseases affecting bone and head and neck tumor. Eight orbital parameters such as Orbital width, orbital height, orbital roof length, orbital floor-length, lateral orbital wall length, medial orbital wall length, intraorbital distance, and extra orbital distance were measured for all the 3D CT images using RadiAnt DICOM Viewer (64 bit). Statistical Analysis: Descriptive statistics including mean, standard deviation, and percentage distribution were calculated. Mann Whitney U-test assessed the comparison between groups. The linear regression equation and Wilk's lambda were also calculated for every parameter. Results: All the orbital measurements except for intraorbital distance were statistically significant between male and female subjects. Totally, 92.0% of the individuals were correctly classified. Conclusions: Orbital measurements were significantly larger in males than in females. Orbits exhibit the least dimensional change throughout one's life. Hence, it could be used as an adjunct in biological sex determination.

In the present study, H12 tool steel is machined with copper and copper–tungsten electrode using the EDM process. Taguchi L9 OA, ANOVA, and S/N ratio are used to study the parameter’s effects on roughness. The effect of peak current is more in machining with a copper electrode, whereas the gap voltage is found to be more effective with copper–tungsten electrode. The addition of tungsten minimizes the surface roughness of steel.

Previous investigations of ionospheric storm-enhanced density (SED) and tongue of ionization (TOI) focused mostly on the behavior of TOI during intense geomagnetic storms. Little attention has been paid to the spatial and temporal variations of TOI during weak to moderate geomagnetic disturbed conditions. In this paper we investigate the source and development of TOI during a moderate geomagnetic storm on 14 October 2012. Multi-instrumental observations including GPS total electron content (TEC), Defense Meteorological Satellite Program (DMSP) in situ measured total ion concentration and ion drift velocity, SuperDARN measured polar ion convection patterns, and electron density profiles from the Poker Flat Incoherent Scatter Radar (PFISR) have been utilized in the current analysis. GPS TEC maps show salient TOI structures persisting for about 5 h over high latitudes of North America on 14 October 2012 in the later recovery phase of the storm when the magnitudes of IMF By and Bz were less than 5 nT. The PFISR electron density profiles indicate that the extra ionization for TEC enhancements mainly occurred in the topside ionosphere with no obvious changes in the bottomside ionosphere and vertical plasma drifts. Additionally, there were no signatures of penetration electric fields in the equatorial electrojet data and upward ion drifts at high latitudes. At the same time, strong subauroral polarization streams with ion drift speeds exceeding 2.5 km/s carried sunward fluxes and migrated toward lower latitudes for about 5° based on the DMSP cross-track drift measurements. Based on those measurements, we postulate that the combined effects of initial build-up of ionization at midlatitudes through daytime production of ionization and equatorward (or less poleward than normal daytime) neutral wind reducing downward diffusion along the inclined filed lines, and an expanded polar ion convection pattern and its associated horizontal plasma transport are important in the formation of the TOI.

There are several methods to improve surface characteristics. Detonation Gun coating (D-Spray) is one of the popular method in thermal spray coating technique. Generally, to enhance the surface properties like wear and corrosion resistance, microhardness, surface finish etc.. D-Spray process was preferred. In this present study, the property of surface finish was considered for the coating powders of WC 14Co and WC 14Co+CNT. The Powder WC 14Co+CNT was prepared in a systematic way and coating process was carried out by using detonation gun coating technique. Scanning Electron Microscopy (SEM) had been done on the powders of with and without CNT and Atomic force Microscopy (AFM) analysis on the surface was done for various places on the surface. A significant effect on the surface finish was exhibited.

This thematic series contains 4 papers mostly presented at the 2016 AOGS meeting in Beijing. The four papers investigate four key regions in the magnetosphere–ionosphere coupling process: mid-tail magnetosphere, near-Earth magnetosphere, inner magnetosphere, and the polar ground region. Guo et al. (Geosci Lett 4:18, 2017) study the current system in reconnection region using 2.5D particle-in-cell simulations. Yao et al. (Geosci Lett 4:8, 2017) use conjugate measurements from ground auroral imagers and in situ THEMIS spacecraft to reveal the mechanism for the wave-like auroral structures prior to substorm onset. Zhang et al. (Geosci Lett 4:20, 2017) investigate the profiles of resonance zone and resonant frequency in the Landau resonance between radiation belt electrons and magnetosonic waves and between protons and cyclotron waves. Rae et al. (Geosci Lett 4:23, 2017) determine the relative timing between sudden increases in amplitude, or onsets, of different ultra-low-frequency wave bands during substorms.

A computer program is developed to automatically identify the geomagnetic storms in Dst index by applying four selection criteria that minimize non-storm-like fluctuations. The program is used to identify the storms in Kyoto Dst and USGS Dst in 50 years (1958–2007). The identified storms (DstMin ≤ −50 nT) are used to investigate their seasonal variations. It is found that the overall seasonal variations of the storm parameters such as occurrence, average intensity (average DstMin) and average strength (average ⟨DstMP⟩) in both versions of Dst exhibit clear semiannual variations with equinoctial maxima and solstice minima; and the maxima and minima in intensity and strength (~±17% each) are less than those in occurrence (~±28%). Wavelet spectra of the storms reveal the existence of distinct semiannual component in four solar cycles (SCs 20–23) and weak longer and shorter-period components in some SCs. The semiannual variation observed also in the mean energy input during the main phase (MP) of the storms estimated from Dst is interpreted in terms of the (1) equinoctial mechanism based on the varying angle between the Earth–Sun line and Earth’s dipole axis and (2) Russell–Mcpherron effect based on the varying angle between the GSM Z-axis and GSE Y-axis; and the yearly range of the dipole tilt angle µ (23.2°) involved in the equinoctial mechanism is found larger than the title angle θ (16.3°) involved in the RM effect. Graphical Abstract .

We present a detailed investigation of the solar rotation effects on the Martian high-latitude (~63°N–81°N) ionosphere using the electron density (Ne) data measured by Mars Global Surveyor and solar XUV and EUV fluxes measured by SOHO under high (2000–2001), medium (2003), and low (2005) solar activity conditions. A fast Fourier transform spectral analysis method is used to estimate the amplitude of the rotation period in these parameters. This method clearly reveals the presence of solar rotation effects in the Martian ionospheric Ne at all altitudes (90–220 km), peak electron density (NmM2), and total electron content under the three solar activity conditions. These effects are in phase with the solar UV fluxes (corrected for the Martian orbit). The period of rotation effect (~26 days) is the same at all altitudes, though its amplitude is strongest at the ionospheric M2 peak (~135–140 km, ~3.5–6% of the mean values) and has a secondary enhancement at the M1 peak (~110–115 km). The effect of solar rotation on the M2 peak is larger during medium solar activity (2003) than during high solar activity (2000–2001). The effect, however, is absent in the ionospheric peak height (hmM2). The rotation effects on Mars are also compared with those on the Earth. Unlike at Mars, the Earth's high-latitude ionosphere shows no clear solar rotation effect, though the effect is observed clearly at lower latitudes.

Detonation gun spray coating method (D-Spray) is an effective method of coating process [4]. The surface property of material will be enhanced by deposition of coating powders such as metal oxides and ceramics like aluminium oxides, tungsten carbide, nickel chromium etc. which improves micro hardness, corrosion and wear resistant resistance property. This coating process is applicable in different engineering sectors such as aviation industry, marine industry, biomedical industry etc., In this Experimental study the Process parameter optimization of D-spray coating process with different coating powder was done by Taguchi design of experiment [2] and interrelationships among multiple response was analysed with Grey relation Analysis [2] in order to find the optimized processing conditions and to get higher quality of coating. Micro hardness Wear resistant, Surface roughness are the multiple responses estimated for various combinations of parameters and the optimum process parameters were obtained.

Detonation gun spray coating method (D-Spray) [1] is one of the effective method of thermal spray coating process. The surface of material or substrate will be enhanced by deposition of coating powders such as metal oxides and ceramics like aluminium oxides, tungsten carbide ,nickel chromium etc by D-spray method that prevents the metal from corrosion and to increase the wear resistance. This coating process had wide applications in different engineering sectors such as aviation industry, marine industry, biomedical industry etc., In this Experimental study the Process parameter optimization of D-spray coating process which is one of the Thermal spray Coating process was done by Taguchi method, [3] in order to find the best processing conditions and to get higher quality of coating. [6] Microhardness was estimated for various combinations of parameters and the optimum process parameters were obtained. Best combination of process parameters has been predicted which results that the thickness of the coating has got a major effect.

The life in our body is as long the blood is flowing, the moment the circulation of blood is stopped (stagnant) the body becomes dead. The message is anything stagnant become dead or useless. The same mantra of the business organization also. In an organization the larger portion of the current assets is inventories. As long as the inventories are converted to finished goods and the cash realization is happening without any delay with the prescribed time frame the organization is moving forward. The movement the inventories are stagnated for a long period the inventory cost will kill the organization. There are many different inventories controlling techniques are used by different company depending upon their situation. Mainly automotive, FMCG, Pharmaceuticals companies adopted many different techniques. I have not come across any such research paper for wind turbine companies. The objective of this paper is to study the entire raw material inventory of a wind turbine company and give the solution for the optimization of inventory.The organization where I did the study is an assembly of Nacelle, Hub, and manufacturing of Blade. All other components are outsourced. The entire inventory system to be studied, and establish the ABC & VED analysis and merge both VED& ABC matrix analysis, Establish critical inventories to be focused by the top management for optimization of inventories. Such study will give a major focus by the management and control the inventories based on sales order and project installation. This will give major benefit to the organization.

The paper investigates the capability of geomagnetic storm parameters in the disturbance storm-time (Dst), Kp, and AE indices to distinguish between severe space weather (SvSW) that causes the reported electric power outages and/or telecommunication failures and normal space weather (NSW) that does not cause these severe effects in a 50 yr period (1958–2007). The parameters include the storm intensities DstMin (minimum Dst during the main phase, MP, of the storm), (dDst/dt)MPmax, Kpmax, and AEmax. In addition, the impulsive parameter $\mathrm{IpsDst}=(-1/{T}_{\mathrm{MP}}){\int }_{\mathrm{TMP}}| {\mathrm{Dst}}_{\mathrm{MP}}| {dt}$ is derived for the storms that are automatically identified in the Kyoto Dst and USGS $\mathrm{Dst}.{\int }_{\mathrm{TMP}}| {\mathrm{Dst}}_{\mathrm{MP}}| {dt}$ is the integral of the modulus of the Dst from onset of the MP (MPO) to the DstMin. T MP is the MP duration from MPO to DstMin. The corresponding mean values $\langle {\mathrm{Kp}}_{\mathrm{MP}}\rangle $ and $\langle {\mathrm{AE}}_{\mathrm{MP}}\rangle $ are also calculated. Regardless of the significant differences in the storm parameters between the two Dst indices, the IpsDst in both indices seems to identify four of the five SvSW events (and the Carrington event) in more than 750 NSW events that have been reported to have occurred in 1958–2007, while all other parameters separate one or two SvSWs from the NSWs. Using the Kyoto IpsDst threshold of −250 nT, we demonstrate a 100% true SvSW identification rate with only one false NSW. Using the false NSW event (1972 August 4), we investigate whether using a higher resolution Dst might result in a more accurate identification of SvSWs. The mechanism of the impulsive action leading to large IpsDst and SvSW involves the coincidence that the fast interplanetary coronal mass ejection velocity V contains its shock (or front) velocity $\bigtriangleup V$ and large interplanetary magnetic field Bz southward covering $\bigtriangleup V$.

[1] Indian scientists got the unique opportunity to study the near-Earth environment during a long annular solar eclipse at the end of the last long deep solar minimum, on 15 January 2010. Continuous high time resolution records of the atmospheric electric parameters and meteorological parameters were made at Tirunelveli (8.07°N, 77.08°E, 35 m Above Mean Sea Level (AMSL) and Braemore Hill (8.41°N, 76.59°E, 460 m AMSL) stations where the eclipse was during 11:07:57–15:06:52 IST with maximum obscuration (~90%) at 13:17:09 Indian Standard Time (IST). The recorded values of the parameters show marked deviations from those normally observed on control fair-weather days. The ambient electric field underwent a large drop by up to 65% during the eclipse, and potential gradient showed epochs of enhancements during and after the eclipse until postsunset. The data also seem to reveal the long lasting paradox of conductivity enhancement during eclipse, which may be due to the eclipse induced upsurge of low winds or waves that brings high density of free space charges embedded in air parcels.

[1] Although the basic mechanism of an additional stratification of the daytime equatorial F region, called the F3 layer, has been explained, two observational aspects that remain not so clear are its summer-winter differences and simultaneous occurrences on either side of the geomagnetic equator. In this paper, we address these two aspects using simultaneous observations of the F3 layer and vertical E×B drift velocity made for the first time in an Indian station Gadanki (6.5°N mag. lat) during the low solar activity period 2008–2009, and making model computations using the Sheffield University Plasmasphere Ionosphere Model. The observations confirm the frequent occurrence of the F3 layer in summer months compared to winter months; the observations also reveal the occasional occurrence of clear and distinct F3 layer in winter although such a layer is frequent in summer. In addition, a threshold vertical plasma velocity (involving the E×B drift and neutral wind) and its time integrated value are found to be important for the formation of the F3 layer. The model results qualitatively reproduce the observations; and show that irrespective of season the formation of the F3 layer is centered on that side of the equator where the equatorward neutral wind reduces the downward field-aligned flow of plasma, and the latitude band of the layer can extend to the opposite hemisphere, especially when the vertical plasma velocity is large.

[1] This study examines the seasonal and interannual variation of the major migrating tidal components in midlatitude to low-latitude total electron content (TEC) observations from the FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellite constellation from 2007 to 2011. Although the absolute amplitudes of the TEC zonal mean and migrating tidal components show a strong positive relation to the increasing and decreasing phases of the solar cycle, the relative tidal amplitudes following normalization by maximum background values show a more varied response to solar activity levels. Features of ionospheric local time variation produced by individual migrating tidal components are consistent from year to year, with DW1 forming the equatorial daytime peak in TEC, SW2 corresponding to the generation of the equatorial ionization anomaly (EIA) crests, and TW3 contributing to the TEC trough between the EIA crests. Numerical experiments using Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) are also performed to determine the sensitivity of the ionospheric migrating tides to upward propagating migrating tidal components from the neutral mesosphere and lower thermosphere (MLT). Zonal mean TECs decrease when MLT tidal forcing is applied and are particularly sensitive to the MLT DW1. Most of the ionospheric SW2 response is attributable to MLT SW2 forcing, enhancing the EIA crests by amplifying the equatorial fountain. TW3 in the model is generated through both in situ photoionization and nonlinear interaction between DW1 and SW2.

[1] The paper studies the physical mechanisms of the ionospheric storms at equatorial and higher latitudes, which are generally opposite both during the main phase (MP) and recovery phase (RP) of geomagnetic storms. The mechanisms are based on the natural tendency of physical systems to occupy minimum energy state which is most stable. The paper first illustrates the recent developments in the understanding of the mechanisms during daytime MPs when generally negative ionospheric storms (in Nmax and TEC) develop at equatorial latitudes and positive storms occur at higher latitudes, including why the storms are severe only in some cases. The paper then investigates the relative importance of the physical mechanisms of the positive ionospheric storms observed at equatorial latitudes (within ±15°) during daytime RPs when negative storms occur at higher latitudes using CHAMP Ne and GPS-TEC data and Sheffield University Plasmasphere Ionosphere Model. The results indicate that the mechanical effect of the storm-time equatorward neutral winds that causes plasma convergence at equatorial F region could be a major source for the positive storms, with the downwelling effect of the winds and zero or westward electric field, if present, acting as minor sources.

Various researches are being conducted in many parts of the world, to improve the surface characteristics of the materials. Thermal spray coating is one of the methods used for enhancing the surface property of the material. Our experiment deals with the study of detonation gun spray coating of WC-12Co, WC-10Co-4Cr and Cr2C3-25NiCr powders. The coating was done on SS316 substrate by varying the process parameters. The process parameters were optimized using Taguchi method to obtain greater hardness.

Solar terrestrial (ST) sciences started centuries ago and branched into different disciplines. Starting with naked eye to highly sophisticated novel experimental techniques, observations have revealed the secrets of the Sun, heliosphere, magnetosphere, plasmasphere, and ionosphere-atmosphere components of the ST system. Theories and theoretical models have been developed for the different components independently and together. World-wide efforts under different umbrella are being persuaded to understand the challenges of the ST system. The onset problem and role of O+ ions in sub-storm physics are two issues that are hotly debated. The onset problem is whether sub-storm is triggered by magnetic reconnection in the tail region at 15–20 Re or by a current disruption at ~12 Re. The issue on O+ role is whether O+ ions affect the dynamics of sub-storms under magnetic storm and non-storm conditions differently. This special issue of Geoscience Letters contains a collection of 15 papers on the history and development of solar terrestrial sciences including auroral sub-storms. Over half of the papers are based on the presentations in a session on the same topic organized at the AOGS (Asia Oceania geosciences Society) General Assembly held in Singapore during 02–07 August 2015. The rest of the papers from outside the assembly also falls within the theme of the special issue. The papers are organized in the order of history and development of ST coupling, sub-storms, and outer heliosphere.

The paper studies the relative importance of penetrating eastward electric field (PEEF) and direct effects of equatorward neutral wind in leading to positive ionospheric storms at low-mid latitudes using observations and modeling. The observations show strong positive ionospheric storms in total electron content (TEC) and peak electron density (N max) at low-mid latitudes in Japan longitudes (≈125°E–145°E) during the first main phase (started at sunrise on 08 November) of a super double geomagnetic storm during 07–11 November 2004. The model results obtained using the Sheffield University Plasmashpere Ionosphere Model (SUPIM) show that the direct effects of storm-time equatorward neutral wind (that reduce poleward plasma flow and raise the ionosphere to high altitudes of reduced chemical loss) can be the main driver of positive ionospheric storms at low-mid latitudes except in N max around the equator. The equatorward wind without PEEF can also result in stronger positive ionospheric storms than with PEEF. Though PEEF on its own is unlikely to cause positive ionospheric storms, it can lead to positive ionospheric storms in the presence of an equatorward wind.

The relative importance of the main drivers of positive ionospheric storms at low-mid latitudes is studied using observations and modeling for the first time. In response to a rare super double geomagnetic storm during 07–11 November 2004, the low-mid latitude (17°–48°N geomag. lat.) ionosphere produced positive ionospheric storms in peak electron density (NmF2) in Japan longitudes (≈125°–145°E) on the day of main phase (MP1) onset (06:30 LT) and negative ionospheric storms in American longitudes (≈65°–120°W) on the following day of MP1 onset (13:00–16:00 LT). The relative effects of the main drivers of the positive ionospheric storms (penetrating daytime eastward electric field, and direct and indirect effects of equatorward neutral wind) are studied using the Sheffield University Plasmasphere Ionosphere Model (SUPIM). The model results show that the penetrating daytime (morning–noon) eastward electric field shifts the equatorial ionisation anomaly crests in NmF2 and TEC (total electron content) to higher than normal latitudes and reduces their values at latitudes at and within the anomaly crests while the direct effects of the equatorward wind (that reduce poleward plasma flow and raise the ionosphere to high altitudes of reduced chemical loss) combined with daytime production of ionisation increase NmF2 and TEC at latitudes poleward of the equatorial region; the later effects can be major causes of positive ionospheric storms at mid latitudes. The downwelling (indirect) effect of the wind increases NmF2 and TEC at low latitudes while its upwelling (indirect) effect reduces NmF2 and TEC at mid latitudes. The net effect of all main drivers is positive ionospheric storms at low-mid latitudes in Japan longitude, which qualitatively agrees with the observations.

The St. Petersburg State Electrotechnical University «LETI» is one of the leading technical higher education institutions in Russia. The present article takes it as an example of a technical school to review problems faced by technical higher education institutions which train personnel and carry out researches in the fields of Electric Power and Electric Engineering, Control in Engineering Systems, Mechatronics and Robotics. The article presents a classification of enterprises which are potential partners of the higher education institution. It also presents suggestions how to overcome the situation.

Vertical total electron content (GPS-TEC) data obtained from the dual-frequency GPS receiver network (GEONET) in Japan are compared with those calculated using the Sheffield University plasmasphere-ionosphere model (SUPIM). The model is also used to estimate the electron content in the plasmaspheric sections of GPS ray paths for the three seasons of high solar activity (F10.7 = 165) under magnetically quiet conditions. According to the estimates, the plasmaspheric sections of vertical GPS ray paths over Japan at altitudes above the O+ to H+ transition height and above the upper altitude (2500 km) of Faraday rotation contain up to 11 and 9 TEC units (1 TEC unit = 1016 electrons m−2) of free electrons, respectively. The free electrons present above the Faraday rotation altitude can cause propagation errors of up to 4.9 ns in time delay and 1.6 m in range at the GPS L1 (1.57542 GHz) frequency. The plasmaspheric electron content, PEC, changes appreciably with season and latitude and very little with the time of the day. However, the percentage contribution of PEC to GPS-TEC changes most significantly with the time of the day; the contribution varies from a minimum of about 12% during daytime at equinox to a maximum of about 60% at night in winter.

Southwestward-propagating medium-scale traveling ionospheric disturbances (MSTIDs) observed over Shigaraki (34.85°N, 136.10°E) in Japan on the night of May 22, 1998 are analyzed in detail. The MSTIDs were detected with a 630.0 nm (OI) all-sky imager at Shigaraki and a large number of GPS (Global Positioning System) receivers distributed around Shigaraki. Each GPS receiver provided total electron content (TEC) between the GPS altitude (20,200 km) and the ground. MSTID amplitudes varied in space and time, and showed decay and enhancement during the southwestward propagation, suggesting that amplitudes of atmospheric gravity waves and the interaction process between gravity waves and F region plasma were highly variable. It is found that spatial and temporal fluctuations of the 630 nm intensity are well correlated with those of GPS-TEC except for a certain period of time. The Scheffield University Plasmasphere Ionosphere Model (SUPIM) is used to obtain theoretical relationships between the 630 nm airglow intensity and GPS-TEC and between their fluctuation amplitudes. The results indicate that the fluctuation amplitudes observed in weak airglow regions are caused by an electron density fluctuation of about ±20% occurring around an altitude of 250 km, where the 630 nm emission rate reaches a maximum, below the F layer peak altitude. Highly enhanced 630 nm intensity and GPS-TEC within a bright airglow region are due to an electron density enhancement of about 150% occurring at altitudes below 300 km.