Modelling Fast-Alfv\'en Mode Conversion Using SPARC

We successfully utilise the SPARC code to model fast-Alfv\'en mode conversion in the region $c_A \gg c_S$ via 3-D MHD numerical simulations of helioseismic waves within constant inclined magnetic field configurations. This was achieved only after empirically modifying the background density and gravitational stratifications in the upper layers of our computational box, as opposed to imposing a traditional Lorentz Force limiter, to ensure a manageable timestep. We found that the latter approach inhibits the fast-Alfv\'en mode conversion process by severely damping the magnetic flux above the surface.Comment: Proceedings of GONG 2012 / LWS/SDO-5 / SOHO 27 (Eclipse on the Coral Sea: Cycle 24 Ascending) Conference, November 12 -16, 2012, Palm Cove, Australi

Directional Time-Distance Probing of Model Sunspot Atmospheres

A crucial feature not widely accounted for in local helioseismology is that surface magnetic regions actually open a window from the interior into the solar atmosphere, and that the seismic waves leak through this window, reflect high in the atmosphere, and then re-enter the interior to rejoin the seismic wave field normally confined there. In a series of recent numerical studies using translation invariant atmospheres, we utilised a "directional time-distance helioseismology" measurement scheme to study the implications of the returning fast and Alfv\'en waves higher up in the solar atmosphere on the seismology at the photosphere (Cally & Moradi 2013; Moradi & Cally 2014). In this study, we extend our directional time-distance analysis to more realistic sunspot-like atmospheres to better understand the direct effects of the magnetic field on helioseismic travel-time measurements in sunspots. In line with our previous findings, we uncover a distinct frequency-dependant directional behaviour in the travel-time measurements, consistent with the signatures of MHD mode conversion. We found this to be the case regardless of the sunspot field strength or depth of its Wilson depression. We also isolated and analysed the direct contribution from purely thermal perturbations to the measured travel times, finding that waves propagating in the umbra are much more sensitive to the underlying thermal effects of the sunspot.Comment: 9 pages, 8 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journa

Helioseismic analysis of the solar flare-induced sunquake of 2005 January 15

We report the discovery of one of the most powerful sunquakes detected to date, produced by an X1.2-class solar flare in active region 10720 on 2005 January 15. We used helioseismic holography to image the source of seismic waves emitted into the solar interior from the site of the flare. Acoustic egression power maps at 3 and 6 mHz with a 2 mHz bandpass reveal a compact acoustic source strongly correlated with impulsive hard X-ray and visible-continuum emission along the penumbral neutral line separating the two major opposing umbrae in the $\delta$-configuration sunspot that predominates AR10720. The acoustic emission signatures were directly aligned with both hard X-ray and visible continuum emission that emanated during the flare. The visible continuum emission is estimated at $2.0 \times 10^{23}$ J, approximately 500 times the seismic emission of $\sim 4 \times 10^{20}$ J. The flare of 2005 January 15 exhibits the same close spatial alignment between the sources of the seismic emission and impulsive visible continuum emission as previous flares, reinforcing the hypothesis that the acoustic emission may be driven by heating of the low photosphere. However, it is a major exception in that there was no signature to indicate the inclusion of protons in the particle beams thought to supply the energy radiated by the flare. The continued strong coincidence between the sources of seismic emission and impulsive visible continuum emission in the case of a proton-deficient white-light flare lends substantial support to the ``back -- warming'' hypothesis, that the low photosphere is significantly heated by intense Balmer and Paschen continuum-edge radiation from the overlying chromosphere in white-light flares.Comment: 12 pages, 7 figures, published in MNRA

Implementation and Evaluation of a Cooperative Vehicle-to-Pedestrian Safety Application

While the development of Vehicle-to-Vehicle (V2V) safety applications based on Dedicated Short-Range Communications (DSRC) has been extensively undergoing standardization for more than a decade, such applications are extremely missing for Vulnerable Road Users (VRUs). Nonexistence of collaborative systems between VRUs and vehicles was the main reason for this lack of attention. Recent developments in Wi-Fi Direct and DSRC-enabled smartphones are changing this perspective. Leveraging the existing V2V platforms, we propose a new framework using a DSRC-enabled smartphone to extend safety benefits to VRUs. The interoperability of applications between vehicles and portable DSRC enabled devices is achieved through the SAE J2735 Personal Safety Message (PSM). However, considering the fact that VRU movement dynamics, response times, and crash scenarios are fundamentally different from vehicles, a specific framework should be designed for VRU safety applications to study their performance. In this article, we first propose an end-to-end Vehicle-to-Pedestrian (V2P) framework to provide situational awareness and hazard detection based on the most common and injury-prone crash scenarios. The details of our VRU safety module, including target classification and collision detection algorithms, are explained next. Furthermore, we propose and evaluate a mitigating solution for congestion and power consumption issues in such systems. Finally, the whole system is implemented and analyzed for realistic crash scenarios

The Effect of Acupressure at GB-21 and SP-6 Acupoints on Anxiety Level and Maternal-Fetal Attachment in Primiparous Women: a Randomized Controlled Clinical Trial

Background: Delivery is one of the most stressful events in women’s life. Excessive anxiety, in turn, increases delivery and pregnancy complications. Mother’s positive experience of delivery leads to more effective maternal-fetal attachment in the first few hours of birth. Objectives: The present study aimed to compare the effects of acupressure at two different acupoints on anxiety level and maternal-fetal attachment in primiparous women. Materials and Methods: In this study, 150 primiparous women were allocated to acupressure at GB-21 acupoint, acupressure at SP-6 acupoint, and control group. The women in their active phase of delivery were enrolled in the study and pressure was applied to the acupoints for 20 minutes. Mother’s anxiety level was assessed using Spielberger’s questionnaire before and one hour after the intervention. In addition, maternal-fetal attachment behaviors were evaluated using Avant’s questionnaire during the first breastfeeding. Then the data were introduced to the SPSS (v. 13) and were analyzed using t test and one way ANOVA. Results: The results revealed no significant difference among the three groups regarding the anxiety level before the intervention (P > 0.05). One hour after the intervention, this measure was significantly lower in the intervention groups in comparison to the control group (P 0.05). Moreover, maternal-fetal attachment was higher in the intervention groups in comparison with the control group (P < 0.001). Conclusions: Acupressure at both acupoints reduced anxiety level and increased maternal-fetal attachment. This method can be easily used in the delivery room

A theory of non-local linear drift wave transport

Transport events in turbulent tokamak plasmas often exhibit non-local or non-diffusive action at a distance features that so far have eluded a conclusive theoretical description. In this paper a theory of non-local transport is investigated through a Fokker-Planck equation with fractional velocity derivatives. A dispersion relation for density gradient driven linear drift modes is derived including the effects of the fractional velocity derivative in the Fokker-Planck equation. It is found that a small deviation (a few percent) from the Maxwellian distribution function alters the dispersion relation such that the growth rates are substantially increased and thereby may cause enhanced levels of transport.Comment: 22 pages, 2 figures. Manuscript submitted to Physics of Plasma

A Fractional Fokker-Planck Model for Anomalous Diffusion

In this paper we present a study of anomalous diffusion using a Fokker-Planck description with fractional velocity derivatives. The distribution functions are found using numerical means for varying degree of fractionality observing the transition from a Gaussian distribution to a L\'evy distribution. The statistical properties of the distribution functions are assessed by a generalized expectation measure and entropy in terms of Tsallis statistical mechanics. We find that the ratio of the generalized entropy and expectation is increasing with decreasing fractionality towards the well known so-called sub-diffusive domain, indicating a self-organising behavior.Comment: 22 pages, 14 figure

A comparative study between codes of spectrum for a single degree of freedom (sdof) system in two different hazardous regions.

Since in structure and earthquake engineering design of structures using response spectrum method (RSM) is very important, this study has been performed for a single degree of freedom (SDOF) system. Firstly the concept and the way of construction of response spectrum has been briefly explained. Then the records of some strong earthquakes in USA and Iran as two hazardous regions have been plotted, after that selected response spectrums (RS) of each country has been compared with each other and finally with standard response code of its own country. It was concluded:1) For a given ground motion the response of a SDOF system only depends on its natural vibration period (T) and damping ratio(ζ).2) When the effective damping ratio of a structure increases, its dynamic responses will decrease which demands the use of higher value of damping ratio in the structure. Also the FORTRAN computer programme for solving the Duhamel's Integral has been improved in this paper