Investigation of traveling ionospheric disturbances

Maximum entropy power spectra of the ionospheric electron density were constructed to enable PINY to compare them with the power independently obtained by PINY with in situ measurements of ionospheric electron density and neutral species performed with instrumentation carried by the Atmospheric Explorer (AE) satellite. This comparison corroborated evidence on the geophysical reality of the alleged electron density irregularities detected by the ASTP dual frequency Doppler link. Roughly half of the localized wave structures which are confined to dimensions of 1800 km or less (as seen by an orbiting Doppler baseline) were found to be associated with the larger crest of the geomagnetic anomaly in the Southern (winter) Hemisphere in the morning. The observed nighttime structures are also associated with local peaks in the electron density

Doppler measurements of the ionosphere on the occasion of the Apollo-Soyuz test project. Part 2: Inversion of differential and rotating Doppler shifts

The preparation of the analytical approach and of the related software used in the inversion of the differential and rotating Doppler data obtained from the ionospheric experiment of the Apollo-Soyuz Test Project (ASTP) is discussed. These data were collected in space-to-space paths (between the ASTP Docking Module (DM) and the Apollo Command Service Module and in space-to-ground paths (between the DM and ground). The Doppler links operated at 162 and 324 MHz and have an accuracy better than 3 MHz over 10-sec integration time. The inversion approach was tested with dummy data obtained with a computer simulation. It was found that a measurement accuracy of 1 to 10% in the value of the horizontal electron density gradient at 221-km altitude can be achieved, in space-to-space paths. For space-to-ground paths near the orbital plane, possible effects of the horizontal gradients on the received differential Doppler shifts were identified. It was possible to reduce the gradient-associated errors in the inversion that leads to the columnar electron content by approximately one-half. Accuracies of 5 to 10% in columnar electron content are achievable, with this gradient-compensation technique

Epistemic Protocols for Distributed Gossiping

Gossip protocols aim at arriving, by means of point-to-point or group communications, at a situation in which all the agents know each other's secrets. We consider distributed gossip protocols which are expressed by means of epistemic logic. We provide an operational semantics of such protocols and set up an appropriate framework to argue about their correctness. Then we analyze specific protocols for complete graphs and for directed rings.Comment: In Proceedings TARK 2015, arXiv:1606.0729

System engineering study of electrodynamic tether as a spaceborne generator and radiator of electromagnetic waves in the ULF/ELF frequency band

The transmission and generation by orbiting tethered satellite systems of information carrying electromagnetic waves in the ULF/ELF frequency band to the Earth at suitably high signal intensities was examined and the system maintaining these intensities in their orbits for long periods of time without excessive onboard power requirements was investigated. The injection quantity power into electromagnetic waves as a function of system parameters such as tether length and orbital height was estimated. The basic equations needed to evaluate alternataing current tethered systems for external energy requirements are presented. The energy equations to tethered systems with various lengths, tether resistances, and radiation resistances, operating at different current values are applied. Radiation resistance as a function of tether length and orbital height is discussed. It is found that ULF/ELF continuously radiating systems could be maintained in orbit with moderate power requirements. The effect of tether length on the power going into electromagnetic waves and whether a single or dual tether system is preferable for the self-driven mode is discussed. It is concluded that the single tether system is preferable over the dual system

Shadows of Relic Neutrino Masses and Spectra on Highest Energy GZK Cosmic Rays

The Ultra High Energy (UHE) neutrino scattering onto relic cosmic neutrinos in galactic and local halos offers an unique way to overcome GZK cut-off. The UHE nu secondary of UHE photo-pion decays may escape the GZK cut-off and travel on cosmic distances hitting local light relic neutrinos clustered in dark halos. The Z resonant production and the competitive W^+W^-, ZZ pair production define a characteristic imprint on hadronic consequent UHECR spectra. This imprint keeps memory both of the primary UHE nu spectra as well as of the possible relic neutrino masses values, energy spectra and relic densities. Such an hadronic showering imprint should reflect into spectra morphology of cosmic rays near and above GZK 10^{19}-10^{21}eV cut-off energies. A possible neutrino degenerate masses at eVs or a more complex and significant neutrino mass split below or near Super-Kamiokande \triangle m_{\nu_{SK}}= 0.1 eV masses might be reflected after each corresponding Z peak showering, into new twin unexpected UHECR flux modulation behind GZK energies: E_{p} sim 3(frac{triangle m_{\nu_{SK}}}/m_{\nu}10^{21}),eV. Other shadowsof lightest, nearly massless, neutrinos m_{nu_{2K} simeq 0.001eV simeq kT_{\nu}, their lowest relic temperatures, energies and densities might be also reflected at even higher energies edges near Grand Unification: E_{p} \sim 2.2(m_{\nu_{2K}/E_{\nu}})10^{23}, eV .Comment: 14 pages, 6 Figures,Invited Talk Heidelberg DARK 200

Hydrologic vulnerability to climate change of the Mandrone glacier (Adamello-Presanella group, Italian Alps)

In order to assess the annual mass balance of the Mandrone glacier in the Central Alps an energy-balance model was applied, supported by snowpack, meteorological and glaciological observations, together with satellite measurements of snow covered areas and albedo. The Physically based Distributed Snow Land and Ice Model (PDSLIM), a distributed multi-layer model for temperate glaciers, which was previously tested on both basin and point scales, was applied. Verification was performed with a network of ablation stakes over two summer periods. Satellite images processed within the Global Land Ice Measurements from Space (GLIMS) project were used to estimate the ice albedo and to verify the position of the simulated transient snowline on specific dates. The energy balance was estimated for the Mandrone and Presena glaciers in the Central Italian Alps. Their modeled balances (−1439 and −1503 mm w.e. year−1, respectively), estimated over a 15 year period, are in good agreement with those obtained with the glaciological method for the Caresèr glacier, a WGMS (World Glacier Monitoring Service) reference located in the nearby Ortles-Cevedale group. Projections according to the regional climate model COSMO-CLM (standing for COnsortium for Small-scale MOdeling model in CLimate Mode) indicate that the Mandrone glacier might not survive the current century and might be halved in size by 2050

Potential climate change effects on the meteorological forcing and the design efficiency of urban drainage systems

Urban drainage systems design and management are strictly connected to meteorological forcing. For design purposes synthetic forms (e.g. depth duration frequency curves) are usually adopted to represent the meteorological solicitation, while a stochastic representation could be more promptly used to investigate the effects of potential climate change both on the design and on the efficiency of urban drainage devices. A simplified semi-probabilistic approach, relying on simple models of the stochastic rainfall process and of the rainfall-runoff (hydrological) transformation, is expected to be a sound tool. Since the rainfall process is described through the definition of three random variables and their probability distribution, the main advantage is the possibility of changing one, two or more characteristics of the rainfall model at a time. The effect of the change can then be easily evaluated through the application of the hydrological model. The semi-probabilistic approach is applied to study some aspects of the drainage system design for locations in the Italian territory. Potential effects of climate change on fictitious urban basins are evaluated through a rainfall stochastic model calibrated on the basis of long series observations recorded at site. Precipitation climate change scenarios were defined on the basis of both international climate studies report and local meteorological observation analysis. The effects on the urban drainage system are evaluated with respect to specific urban drainage devices and the efficiency of the design procedure in the hypothesis of climate change is finally discussed

Large-scale clique cover of real-world networks

The edge clique cover (ECC ) problem deals with discovering a set of (possibly overlapping) cliques in a given graph that covers each of the graph's edges. This problem finds applications ranging from social networks to compiler optimization and stringology. We consider several variants of the ECC problem, using classical quality measures (like the number of cliques) and new ones. We describe efficient heuristic algorithms, the fastest one taking O(mdG) time for a graph with m edges, degeneracy dG (also known as k-core number). For large real-world networks with millions of nodes, like social networks, an algorithm should have (almost) linear running time to be practical: Our algorithm for finding ECCs of large networks has linear-time performance in practice because dG is small, as our experiments show, on real-world networks with thousands to several million nodes