Momentum flux, energy flux and pressure drag associated with mountain wave across western ghat

An attempt has been made to parameterize the wave momentum flux wave energy flux and pressure drag associated with mountain wave across the Mumbai-Pune section of western ghat mountain in India. A two dimensional frictionless, adiabatic, hydrostatic, Boussinesq flow with constant basic flow (U) and constant Brunt Vaisala frequency (N) across a mesoscale mountain with infinite extension in the Cross wind direction, has been considered here. It has been shown that for a vertically propagating (or decaying) waves the wave momentum flux is downward (or upward) and the wave energy flux is upward (or downward). It has also been shown that both the fluxes are independent of the half width of the bell shaped part of the western ghat. The analytically derived formula have been used to compute the pressure drag and to find out the vertical profile of wave momentum flux and wave energy flux for different cases of mountain wave across western ghat, as reported by earlier workers.

Energy Flux and Conductance from Meso-Scale Auroral Features Observed by All-Sky-Imagers

<p>Earth’s Magnetosphere-Ionosphere-Thermosphere system is inseparably coupled, with driving from above and below by various terrestrial and space weather phenomena. Global models have done well at capturing large-scale effects, but currently do not capture the meso-scale (~10s-500 km) phenomena which often are locally more intense. As computing power improves, and modeling meso-scales now becomes possible, it is vital to provide data-informed inputs of the relevant drivers. In this presentation, we focus on the energy flux deposited into the ionosphere from the magnetosphere by precipitating particles that result in the aurora, specifically at meso-scales, and the resulting conductance. Thanks to NASA’s THEMIS mission, an array of all-sky-imagers (ASIs) across Canada monitors the majority of the nightside auroral oval at a 3 second cadence, providing a global view at temporal & spatial resolutions required to study the aurora on meso-scales. Thus, we present 2-D maps over time of the energy flux, energy, and conductance that result from the aurora during solar storms and substorms, including those features at meso-scales. We determine conductance using the ASI-determined eflux and energy as inputs to the Boltzman Three Constituent (B3C) auroral transport code, compare values with Poker Flat ISR observations, and find a good comparison. We find that meso-scale aurora contributes at least 60-70% of the total precipitated energy flux during the first ten minutes of a substorm. Our results can be utilized by the broad community, for example, as inputs to atmospheric models or as the resulting conductance from precipitation inferred by magnetospheric models or satellite observations.</p>

EVALUATION OF THE DOSE LEVELS IN THE IRRADIATION CHANNELS OF PU-BE NEUTRON SOURCES STORAGE DEVICE BY USING NEUTRON ACTIVATION ANALYSIS AND MCNP6 MODELLING

PuBeneutrons sources of Educational Neutron Laboratory in the Center for Physical Sciences and Technology are used in several activities including neutron activation for educational purposes and laboratory irradiation experiments. In this work we address the dose rate estimation in the irradiation channels of reconstructed PuBe neutron sources storage device in the particular positions dedicated for neutron irradiation experiments using neutron activation analysis (NAA) and MCNP6 modelling.The results on neutron activation of V2O5, MnO2, Al and Na2CO3were analyzed and compared with MCNP6 model prediction results. The conclusions on the actual neutron flux energy distribution and model corrections are drawn. The absolute neutron intensity at dedicated irradiation points as well as neutron and gamma dose rates are obtained.

A Statistical Analysis of Radar Blackouts at Mars: MARSIS, SHARAD and MAVEN Observations

<p>We present an analysis of radar blackouts observed by MARSIS on Mars Express and SHARAD on Mars Reconnaissance Orbiter for the interval 2006 – 2017.  The period of interest encompasses the extended solar minimum between solar cycles 23 and 24 as well as the solar maximum of cycle 24.  Blackouts have been identified by eye through scanning daily plots of the surface reflection for both radars.  A blackout occurs when, for no apparent instrumental reason, the surface reflection normally expected is either not observed (total) or when the surface reflection is seen for only part of the orbit or the surface reflection is both weaker and spread over a significant time delay (partial).  Such blackouts are caused by enhanced ionisation at altitudes below the main ionospheric electron density peak resulting in increased absorption of the radar signal.  There are more occurrences observed by MARSIS than SHARAD, which is expected due to the lower absorption at the higher operating frequency of SHARAD.  We also observe more blackouts during solar maximum than solar minimum.  Indeed, there are no total blackouts during the extended solar minimum, although both radars do have partial blackouts.  There is no apparent relationship between blackout occurrence and crustal magnetic fields.  Following previous work, which has indicated that solar energetic particles, specifically electrons are responsible for the enhanced ionisation in the atmosphere, we also present the analysis of the MAVEN SEP electrons between 20 keV and 2 MeV during events when all three spacecraft were operational.  We find that the SEP electron flux-energy relationship is much enhanced during the total blackouts, in particular where both radars are impacted, while for partial blackouts the flux-energy spectrum is closer to those from orbits where no blackout occurs.  We also find that for certain events, the average spectrum which result in a blackout is particularly enhanced at the higher energy end of the spectrum, above 50 keV. The average spectra from each condition is presented.  We conclude that there is a higher probability of a radar blackout during solar maximum, that crustal magnetic fields play no apparent role in the their observational occurrence, that the higher energy (< 50 keV) electrons are responsible, and that for events where both radars observe a radar blackout the SEP electron fluxes are at their highest.</p>

A Study on Contribution of the Advective Heat Flux to the Energy Closure near the Land Surface in the Zoige Alpine Wetland

<p>The energy non-closure near the land surface has been a key topic in the land surface processes research.  The energy closure rate is still not high even after considering heat storage and photosynthesis energy consumption, while the contribution of advective energy to the closure rate needs to be considered further under the non-uniform underlying surface. In this paper, the advective energy caused by thermal heterogeneity of underlying surface is calculated by using the energy budget data collected from the Flower-Lake observation site in the Zoige Alpine Wetland in 2017, and the contribution of thermal advection to energy closure near the ground is estimated. The result shows: In summer of 2017, the maximum value of the advective heat flux was 23.8w/m2 at the Zoige alpine wetland. When the contribution of advective heat flux is introduced into the energy balance equation, the energy closure rate increases from 72.0% to 79.4%. With considering the contribution of horizontal heat transfer, it has a certain effect on improving energy closure rate for the flat terrain and thermal inhomogeneous underlying surface. The near surface thermal inhomogeneity leads to the accumulation of heat, which is the basic reason for the heat advection to affect the energy closure rate, and also an important reason for the difference between the wetland characteristics of water and heat exchange of the wetland with the other regions.</p><p><strong>Key </strong><strong>words</strong><strong>：</strong>Alpine wetland; eddy correlation; advective heat flux; energy closure rate; inhomogeneous land surface</p>

Mobility Edges in One-dimensional Disordered Aharonov-Bohm Rings

We study numerically the localization properties of the eigenstates of a tight-binding Hamiltonian model for noninteracting electrons moving in a one-dimensional disordered ring pierced by an Aharonov-Bohm flux. By analyzing the dependence of the inverse participation ratio on Aharonov-Bohm flux, energy, disorder strength and system size, we find that all states in the ring are delocalized in the weak disorder limit. The states lying deeply in the band tails will undergo a continuous delocalization-localization transition as the disorder strength in the ring sweeps from the weak to the strong disorder regime.

The LISA beamline at ESRF

This contribution provides a description of LISA, the new Italian Collaborating Research Group beamline operative at the European Synchrotron Radiation Facility. A presentation of the instruments available and optical devices is given as well as the main X-ray parameters (flux, energy resolution, focal spot dimensions, etc.) and comparison with theoretical calculations. The beamline has been open to users since April 2018 and will be ready at the opening of the Extremely Brilliant Source in late-2020.

Membrane desalination technologies in water treatment: A review

One of the most pressing problems worldwide is inadequate access to potable water. Many technologies have been applied to address this through research to find robust but inexpensive methods of desalination that offer high fluxes and use less energy, while reducing chemical use and environmental impact. Membrane desalination technology is universally considered to solve water shortage problems due to its high efficiency and lower energy consumption than distillation methods. This review focuses on the desalination performance of membrane technologies with consideration of the effect of driving force, potential technologies, membrane types, flux, energy consumption and operating temperature, etc. Pressure driven membrane processes (MF, UF, NF, RO), and their fouling propensity and major drawbacks are discussed briefly. Membrane characteristics and the effects of operating conditions on desalination are also covered. Organic-hybrid and inorganic membrane materials can offer advantages, with high flux, good selectivity, and useful chemical and thermal resistance.

Predicting data quality in biological X-ray solution scattering

Biological small-angle X-ray solution scattering (BioSAXS) is now widely used to gain information on biomolecules in the solution state. Often, however, it is not obvious in advance whether a particular sample will scatter strongly enough to give useful data to draw conclusions under practically achievable solution conditions. Conformational changes that appear to be large may not always produce scattering curves that are distinguishable from each other at realistic concentrations and exposure times. Emerging technologies such as time-resolved SAXS (TR-SAXS) pose additional challenges owing to small beams and short sample path lengths. Beamline optics vary in brilliance and degree of background scatter, and major upgrades and improvements to sources promise to expand the reach of these methods. Computations are developed to estimate BioSAXS sample intensity at a more detailed level than previous approaches, taking into account flux, energy, sample thickness, window material, instrumental background, detector efficiency, solution conditions and other parameters. The results are validated with calibrated experiments using standard proteins on four different beamlines with various fluxes, energies and configurations. The ability of BioSAXS to statistically distinguish a variety of conformational movements under continuous-flow time-resolved conditions is then computed on a set of matched structure pairs drawn from the Database of Macromolecular Motions (http://molmovdb.org). The feasibility of experiments is ranked according to sample consumption, a quantity that varies by over two orders of magnitude for the set of structures. In addition to photon flux, the calculations suggest that window scattering and choice of wavelength are also important factors given the short sample path lengths common in such setups.