Multilayered Distributed Routing for Power Efficient MANET Performance

In this paper a new power efficient routing algorithm for MANETs with self-organizing and self-routing features is described and its performance analyzed in different simulation scenarios. The algorithm has the logic of a non-cooperative routing algorithm based on the evaluation of a weight parameter, the latter being a function of properties of the MANET nodes related to the nominal available power and the transmission range. A self-estimation of this weight parameter for each node is introduced in the routing process based on the status and functional history of the node. The routing is based on network layering, formation of service areas in each layer and choice of nodes from these areas to have the functionality of default gateways. The proposed algorithm, named service zone gateway prediction (SZGP), is a hybrid type of routing mechanism, incorporating pre-computed multipath hop-by-hop distributed routing, with a periodically updated hierarchical multilayered structure. The results from the simulation experiments show that the performance of the proposed SZGP algorithm in relation to the basic performance parameters such as packet delivery ratio, delay and throughput are similar to those of the well-known AODV algorithm, but in relation to power efficiency the proposed algorithm outperforms AODV significantly. This is due to the fact that such an approach reduces the overall number of broadcasts in the network and ensures a reliable and energy efficient connection by balancing the load among the nodes.     

Modulation spectroscopy study of a strained layer GaAs/GaAsP multiple quantum well structure

Using contactless electroreflectance (CER) and piezoreflectance at 300 K we have characterized a GaAs/GaAs_1?xP_x multiple quantum well (MQW) structure, “GaAs” (nominal) and GaAsP epilayers grown by chloride transport chemical vapor deposition on GaAs (001) substrates. From a detailed lineshape fit to the CER data from the epilayers we have determined the energies of the fundamental band gap and hence the phosphorous composition. The nominal “GaAs” epilayers were found to have phosphorous compositions of about 2.5–3.2%, a result of the phosphorous diffusion between growth chambers in the reactor. The GaAs_1?xP_x epilayer had x=0.29. For the GaAs_0.97P_0.03/GaAs_0.71P_0.29MQW comparison between the experimentally observed energies of a number of quantum transitions with a theoretical envelope function calculation, including the effects of strain in the barriers, made it possible to evaluate the unstrained conduction band offset parameter Q_c=0.50±0.05. Our value for this parameter is discussed in relation to other works. Atomic force microscopy was employed to investigate the surface morphology of the 230 Å GaAsP top layer of the MQW in addition to a 2000 Å GaAsP epilayer. From the absence of any cross-hatch pattern associated with misfit dislocations on the former we concluded that the GaAsP in the MQW is pseudomorphic. On the other hand the 2000 Å epilayer exhibited signs of strain relaxation.     

Compact Modules for Wireless Communication Systems in the E-Band (71–76 GHz)

The millimeter-wave spectrum above 70 GHz provides a cost-effective solution to increase the wireless communications data rates by increasing the carrier wave frequencies. We report on the development of two key components of a wireless transmission system, a high-speed photodiode (HS-PD) and a Schottky Barrier Diode (SBD). Both components operate uncooled, a key issue in the development of compact modules. On the transmitter side, an improved design of the HS-PD allows it to deliver an output RF power exceeding 0 dBm (1 mW). On the receiver side, we present the design process and achieved results on the development of a compact direct envelope detection receiver based on a quasi-optical SDB module. Different resonant (meander dipole) and broadband (Log-Spiral and Log-Periodic) planar antenna solutions are designed, matching the antenna and Schottky diode impedances at high frequency. Impedance matching at baseband is also provided by means of an impedance transition to a 50 Ohm output. From this comparison, we demonstrate the excellent performance of the broadband antennas over the entire E-band by setting up a short-range wireless link transmitting a 1 Gbps data signal.     

Comparing the growth of a molecular semiconductor on amorphous and semi-crystalline polycarbonate substrates

Polymeric substrates are of importance in plastic electronics. However, polymeric surfaces can exhibit different morphologies depending on whether they are amorphous or semi-crystalline. This work focuses on the impact of the surface structure of bisphenol A polycarbonate substrates on the nucleation and growth of a p-type semi-conductor, namely zinc phthalocyanine (ZnPc). ZnPc films were deposited under high vacuum at different substrate temperatures on oriented semi-crystalline as well as amorphous substrates of PC. The oriented substrates of PC were prepared by a method combining mechanical rubbing and solvent induced crystallization: the substrates show a periodic and regular alternation of oriented crystalline lamellae. Grazing incidence X-ray diffraction shows that the crystalline lamellae of PC have a preferential (a, c) contact plane. Moreover, the substrates show a bilayer structure made of a 60 nm-thick semi-crystalline overlayer atop an amorphous underlayer. UV–vis spectroscopy shows that the polymorphism of the ZnPc films is not modified by the surface structure of the PC substrate (amorphous versus semi-crystalline). However, the statistical analysis of domain size and density versus substrate temperature T_s evidences different apparent activation energies of the growth mechanism. High Resolution Transmission Electron Microscopy suggests that twinning along a (2 ?1 0) plane accounts for the bifurcations of the in-plane b-axis direction of the ZnPc nanocrystals. On oriented substrates of PC, such bifurcations are partly suppressed by the nanocorrugation of the surface, resulting in larger apparent domain sizes and unidirectional in-plane orientation.     

Synthesis of Multilayered Star‐Shaped B6O Particles Using the Seed‐Mediated Growth Method

In this study, we introduce a simple and effective seed‐mediated growth method (SMGM) for the controlled synthesis of boron suboxide powder. By employing starting powders with different concentrations and adding boron suboxide seeds with a star‐like morphology, we demonstrate that B₆O ceramics that exhibit high‐level crystallinity can be synthesized using SMGM at ambient pressure conditions. The formation of multilayered star‐shaped B₆O particles via SMGM is reported for the first time.     

Effect of Al2O3/(B2O3 + Na2O) Ratio on CaO-Al2O3-Based Mold Fluxes: Melting Property,Viscosity, Heat Transfer,and Structure

Metallurgical and Materials Transactions B - CaO-Al2O3-based mold fluxes, which are under development for the continuous casting of high-Al steel, contain fluxing compounds, such as Na2O and B2O3....     

Study on thermolysis process of a new hydrated and protonated perovskite-like oxides H2K0.5Bi2.5Ti4O13·yH2O

A protonated form of the n?=?4 layered bismuth containing perovskite-like titanate K_2.5Bi_2.5Ti₄O₁₃ belonging to Ruddlesden-Popper phases was prepared via ion exchange reaction of interlayer K⁺ with protons. Its composition was investigated by TG ICP and EDX analysis was found to be H₂K_0.5Bi_2.5Ti₄O₁₃·H₂O. The thermal behavior of the obtained phase was investigated by STA coupled with mass-spectrometry, the structural changes, happening with the sample during heating, were examined by XRD. It was shown that the as-prepared hydrated phase undergoes two-stage dehydration at low temperatures (up to 160?°C). The further heating leads to the gradual decomposition and crystallization of new phases, notably Bi₂Ti₂O₇, Bi₄Ti₃O₁₂ and Bi₂Ti₄O₁₁. The morphology of the as-prepared sample and samples after heat treatment was examined using SEM.     

Density functional modelling in multiphase compositional hydrodynamics

This work is essentially a review of a density functional approach in multiphase hydrodynamics developed by the authors during the last 15 years [Dinariev, J Appl Math Mech 1995;59(5):745–752; Dinariev, J Appl Math Mech 1998;62(3):397–405; Demyanov and Dinariev, Fluid Dynam 2004;39(6):933–944; Demianov et al., “Basics of the Density Functional Theory in Hydrodynamics,” Fizmatlit, Moscow; 2009 (in Russian); Dinariev and Evseev, Fluid Dynam 2010;45(1):85–95]. The basic assumption is a representation of the entropy or the Helmholtz energy of the mixture as a functional that is dependent upon chemical component densities. The hydrodynamic system of equations (local conservation laws for chemical components, momentum, and energy) is used to describe multiphase processes, and the constitutive relations (expressions for stresses, diffusion, and heat fluxes) are derived from entropy growth requirement. The authors present the results of numerical simulations describing static and dynamic multiphase systems.