Key Issues in Expansion of End-User Mobile Communication in China

China’s mobile communications market presents unique market challenges. With a high subscriber growth rate but polarized and stratified consumer adoption trends, an investigation into the current status of this market will improve our understanding on how adoption of mobile communications is evolving. In this descriptive paper we analyze key issues relating to market characteristics of mobile communications with an objective to better comprehend the dynamics of this largest mobile subscribers market. Using secondary data we identify mobile industry and end-user related trends to infer our conclusions for the industry.China;mobile communication;mobile subscribers market

Tidal disruptions in circumbinary disks. II: Observational signatures in the reverberation spectra

Supermassive Binary Black Holes (SMBBHs) with sub-pc separations form in the course of galaxy mergers, if both galaxies harbour massive black holes. Clear observational evidence for them however still eludes us. We propose a novel method of identifying these systems by means of reverberation mapping their circumbinary disk after a tidal disruption event has ionized it. The tidal disruption of a star at the secondary leads to strong asymmetries in the disk response. We model the shape of the velocity--delay maps for various toy disk models and more realistic gas distributions obtained by SPH simulations. The emissivity of the ionized disk is calculated with {\em Cloudy}. We find peculiar asymmetries in the maps for off center ionizing sources that may help us constrain geometrical parameters of a circumbinary disk such as semi-major axis and orbital phase of the secondary, as well as help strengthen the observational evidence for sub-parsec SMBBHs as such.Comment: 10 pages, 5 figures. Accepted for publication in Ap

A comparative assessment of different deviation strategies for dangerous NEO

In this paper a number of deviation strategies for dangerous Near Earth Objects (NEO) have been compared. For each strategy (i.e. Solar Collector, Nuclear Blast, Kinetic Impactor, Low-thrust Propulsion, Mass Driver) a multi criteria optimisation method has been used to reconstruct the set of Pareto optimal solutions minimising the mass of the spacecraft and the warning time, and maximising the deviation. Then, a dominance criterion has been defined and used to compare all the Pareto sets. The achievable deviation at the MOID, either for a low-thrust or for an impulsive variation of the orbit of the NEO, has been computed through a set of analytical formulas. The variation of the orbit of the NEO has been estimated through a deviation action model that takes into account the wet mass of the spacecraft at the Earth. Finally the technology readiness level of each strategy has been used to compute a more realistic value for the required warning time

Auctioning Bulk Mobile Messages

The search for enablers of continued growth of SMS traffic, as well asthe take-off of the more diversified MMS message contents, open up forenterprises the potential of bulk use of mobile messaging , instead ofessentially one-by-one use. In parallel, such enterprises or valueadded services needing mobile messaging in bulk - for spot use or foruse over a prescribed period of time - want to minimize totalacquisition costs, from a set of technically approved providers ofmessaging capacity.This leads naturally to the evaluation of auctioning for bulk SMS orMMS messaging capacity, with the intrinsic advantages therein such asreduction in acquisition costs, allocation efficiency, and optimality.The paper shows, with extensive results as evidence from simulationscarried out in the Rotterdam School of Management e-Auction room, howmulti-attribute reverse auctions perform for the enterprise-buyer, aswell as for the messaging capacity-sellers. We compare 1- and 5-roundauctions, to show the learning effect and the benefits thereof to thevarious parties. The sensitivity will be reported to changes in theenterprise's and the capacity providers utilities and prioritiesbetween message attributes (such as price, size, security, anddelivery delay). At the organizational level, the paper also considersalternate organizational deployment schemes and properties for anoff-line or spot bulk messaging capacity market, subject to technicaland regulatory constraints.MMS;EMS;Mobile commerce;SMS;multi-attribute auctions

A match coefficient approach for damage imaging in structural components by ultrasonic synthetic aperture focus

Ultrasonic Synthetic Aperture Focus (SAF) techniques are commonly used to image structural defects. In this paper, a variation of SAF based on ideas borrowed from Matched Field Processing (MFP) is evaluated to reduce artifacts and sidelobes of the resulting images. In particular, instead of considering the full RF ultrasonic waveforms for the SAF time backpropagation, only selected features from the waveforms are utilized to form a “data vector” and a “replica” (expected) vector of MFP. These vectors are adaptive for the pair of transmitter-receiver and the focus point. The image is created as a matched filter between these two vectors. Experimental results are shown for an isotropic and homogenous metallic plate with simulated defects, probed by six piezoelectric patches used as receivers or transmitters

Investment-specific technology shocks and international business cycles: an empirical assessment

In this paper, we first introduce investment-specific technology (IST) shocks into an otherwise standard international real business cycle model and show that a thoughtful calibration of them along the lines of Raffo (2009) successfully addresses several of the existing puzzles in the literature. In particular, we obtain a negative correlation of relative consumption and the terms of trade (Backus-Smith puzzle), as well as a more volatile real exchange rate, and cross-country output correlations that are higher than consumption correlations (price and quantity puzzles). Then we use data from the Organisation for Economic Co-operation and Development for the relative price of investment to build and estimate these IST processes across the United States and a "rest of the world" aggregate, showing that they are cointegrated and well represented by a vector error–correction model. Finally, we demonstrate that, when we fit such estimated IST processes into the model, the shocks are actually powerless to explain any of the existing puzzles.

A Dynamical System for Plant Pattern Formation: A Rigorous Analysis

We present a rigorous mathematical analysis of a discrete dynamical system modeling plant pattern formation. In this model, based on the work of physicists Douady and Couder, fixed points are the spiral or helical lattices often occurring in plants. The frequent occurrence of the Fibonacci sequence in the number of visible spirals is explained by the stability of the fixed points in this system, as well as by the structure of their bifurcation diagram. We provide a detailed study of this diagram

High-resolution neutron depolarization microscopy of the ferromagnetic transitions in Ni3_3Al and HgCr2_2Se4_4 under pressure

We performed neutron imaging of ferromagnetic transitions in Ni$_3$Al and HgCr$_2$Se$_4$ crystals. These neutron depolarization measurements revealed bulk magnetic inhomogeneities in the ferromagnetic transition temperature with spatial resolution of about 100~$\mu$m. To obtain such spatial resolution, we employed a novel neutron microscope equipped with Wolter mirrors as a neutron image-forming lens and a focusing neutron guide as a neutron condenser lens. The images of Ni$_3$Al show that the sample does not homogeneously go through the ferromagnetic transition; the improved resolution allowed us to identify a distribution of small grains with slightly off-stoichiometric composition. Additionally, neutron depolarization imaging experiments on the chrome spinel, HgCr$_2$Se$_4$, under pressures up to 15~kbar highlight the advantages of the new technique especially for small samples or sample environments with restricted sample space. The improved spatial resolution enables one to observe domain formation in the sample while decreasing the acquisition time despite having a bulky pressure cell in the beam

La ionosfera: comunicare... naturalmente!

La ionosfera è la parte della media-alta atmosfera compresa tra i 60 e i 1000 km di quota. Essa è caratterizzata da una concentrazione di elettroni tale da modificare la propagazione delle onde radio che la attraversano