Modeling and Analysis of UAV-Assisted Mobile Network with Imperfect Beam Alignment

With the rapid development of emerging 5G and beyond (B5G), Unmanned Aerial Vehicles (UAVs) are increasingly important to improve the performance of dense cellular networks. As a conventional metric, coverage probability has been widely studied in communication systems due to the increasing density of users and complexity of the heterogeneous environment. In recent years, stochastic geometry has attracted more attention as a mathematical tool for modeling mobile network systems. In this paper, an analytical approach to the coverage probability analysis of UAV-assisted cellular networks with imperfect beam alignment has been proposed. An assumption was considered that all users are distributed according to Poisson Cluster Process (PCP) around base stations, in particular, Thomas Cluster Process (TCP). Using this model, the impact of beam alignment errors on the coverage probability was investigated. Initially, the Probability Density Function (PDF) of directional antenna gain between the user and its serving base station was obtained. Then, association probability with each tier was achieved. A tractable expression was derived for coverage probability in both Line-of-Sight (LoS) and Non-Line-of-Sight (NLoS) condition links. Numerical results demonstrated that at low UAVs altitude, beam alignment errors significantly degrade coverage performance. Moreover, for a small cluster size, alignment errors do not necessarily affect the coverage performance.     

Development of a 3D HUD using a tunable bandpass filter for wavelength multiplexing

A 3D stereoscopic head‐up display using a tunable bandpass filter to perform left and right image spectral separation is presented. Using a single filter reduces the size and the cost of the head‐up display optical engine and enables each spectral band to be accurately tuned. Experiments performed on the first prototype demonstrate the ability to continuously tune the bandpass frequency on 30‐nm range while keeping a 20‐nm bandwidth. Such a system avoids the use of a bulky and costly rotating wheel and enables the use of holographic optical elements known to be wavelength selective.     

Dislocations interfaciales et cohérence dans le système épitaxique fer-or

Iron was deposited in ultrahigh vacuum onto thin single-crystal films of gold oriented with (111) parallel to the surface plane. Study by electron diffraction and electron microscopy has shown that the initial growth of iron occurs by successive monolayers. Three stages in the deposit growth have been found: first the deposited film of iron is strained to match the gold substrate exactly; then interfacial dislocations appear at the gold-iron interface; and finally iron nuclei of b.c.c. structure are formed. The interfacial dislocations are in mixed orientation with their Burgers vectors $\text{1}\text{2}$a 〈110〉 inclined to the gold-iron interface; it is found that they have a poor efficiency for accommodating the misfit between the substrate and the deposit, so that for deposits of average thickness greater than 8 Å the interface is mostly incoherent.     

Relationship between blood pressure and weight characteristics in childhood and adolescence. II.--Blood pressure, fatness, lean body mass and non lean body mass (author's transl)

The relationship between adiposity and blood pressure has been studied among 17,067 healthy children aged 4 to 18 years old. The correlation of blood pressure with fatness, expressed as non lean body mass, is smaller than the correlation with lean body mass, especially in boys. Blood pressure association with lean body mass strongly increases during puberty growth in boys. These data suggest that during adolescence blood pressure association with weight is mainly due to growth and physical-maturation and that fatness has less influence. A careful analysis of somatic features of adolescents with high blood pressure seems necessary before advocating and improved system of weight control. Preference of blood pressure reference to height is again strengthened.     

A Similarity Metric for Retrieval of Compressed Objects: Application for Mining Satellite Image Time Series

This paper addresses the problem of building an index of compressed object databases. We introduce an informational similarity measure based on the coding length of two part codes. Then, we present a methodology for compressing the database by taking into account interobject redundancies and by using the informational similarity measure. The method produces an index included in the code of the data volume. This index is built such that it contains the minimal sufficient information to discriminate the data-volume objects. Then, we present an optimal two-part coder for compressing spatio-temporal events contained in satellite image time series (SITS). The two-part coder allows us to measure similarity and then to derive an optimal index of SITS spatio-temporal events. The resulting index is representative of the SITS information content and enables queries based on information content.     

Stress and plastic deformation of MEA in running fuel cell

Numerical modelling of mechanical stresses in running fuel cell is provided. The evolution of stresses and plastic deformations in the membrane has been obtained during the turn-on phase. The operating conditions have been taken into account by imposing the heating sources and the humidity field. The results have been presented on two scales: the global scale reflects the stress evolution in the entire fuel cell and the local one corresponds to the tooth/channel structure. It has been shown that the stresses are strongly heterogeneous on the both scales and time dependent. From the mechanical point of view, the most sensible zone is under the GDL/seal joint interface. In the running fuel cell the heterogeneity decreases while it rises in the fuel cell just after the assembly. The stresses reach the maximum values during the humidification step, the magnitude of these stresses is sufficient for initiation of the plastic deformations in the Nafion membrane.     

The borders of mobile handset ecosystems: Is coopetition inevitable?

Today, the mobile phone industry witnesses important changes, shifting from a value chain to a burgeoning business ecosystem. This paper deals with the relationships that are at the very core of mobile OS ecosystems for IMTs (smartphones and PDA): Microsoft-OS, Symbian-OS, Palm-OS and RIM-OS over the period 1998–2006. Our study confirms that an ecosystem’s borders are unclear. More than half of our sample’ relationships are shared by at least two different ecosystems. The ecosystems we studied do not differ in terms of exclusive relationship which suggests that coopetitive strategies are particularly relevant in mobile platforms war.     

High prevalence of antibodies to Mycoplasma penetrans in human immunodeficiency virus-seronegative and -seropositive populations in Brazzaville, Congo

In industrialized countries, the prevalence of antibodies to Mycoplasma penetrans is higher among human immunodeficiency virus (HIV)-seropositive homosexuals than other HIV-seropositive and HIV-seronegative groups. In an African heterosexual population, we found a higher prevalence of M. penetrans antibodies in HIV-seronegative blood donors (15.5%) than in France (0.9%) or the United States (0.3%) and a prevalence of 13.4% in HIV-seropositive individuals. HIV-seropositive individuals with less than 5% CD4 cells had a higher prevalence of M. penetrans antibodies than individuals with 5% or more CD4 cells (25.0 versus 8.5%).     

Functional properties of the α-chain of a major legumin subunit of Pisum sativum legumin

The constituting polypeptides of a heavy pea legumin subunit were separated. The interfacial and emulsifying properties of the α-chains were studied and compared with those of the respective subunit and the native legumin molecules. The α-polypeptides show modified interface behaviour as compared to the legumin. Faster diffusion and higher adsorption barriers during the phase of rearrangement, higher interface coverage in the equilibrium state and improved emulsifying properties were measured.