Model-based implementation of distributed systems with priorities

Model-based application development aims at increasing the application’s integrity by using models employed in clearly defined transformation steps leading to correct-by-construction artifacts. In this paper, we introduce a novel model-based approach for constructing correct distributed implementation of component-based models constrained by priorities. We argue that model-based methods are especially of interest in the context of distributed embedded systems due to their inherent complexity (e.g., caused by non-deterministic nature of distributed systems). Our method is designed based on three phases of transformation. The input is a model specified in terms of a set of behavioral components that interact through a set of high-level synchronization primitives (e.g., rendezvous and broadcasts) and priority rules for scheduling purposes. The first phase transforms the input model into a model that has no priorities. Then, the second phase transforms the deprioritized model into another model that resolves distributed conflicts by incorporating a solution to the committee coordination problem. Finally, the third phase generates distributed code using asynchronous point-to-point message passing primitives (e.g., TCP sockets). All transformations preserve the properties of their input model by ensuring observational equivalence. All the transformations are implemented and our experiments validate their effectiveness.     

A New Criteria Decision Applied on the Primary Synchronization in the DS-WCDMA Interface of the UMTS System

In DS-WCDMA mobile systems such the UMTS, asynchronous cell site operation,assigning different long spreading code to each cell, yields the advantageof flexible system deployment. We can design an indoor system basedon an outdoor one. However, in general, much longer search time isrequired in asynchronous operation than in synchronous. This paperproposes three techniques to take decisions about synchronizationbased on observation of correlated signals. Classical decision criterialike maximum and threshold criterion are presented. A new decisioncriteria that we call Threshold&Max combined decision criteriais analyzed. The results of this new introduced technique is comparedwith the classical ones.     

Tailoring Electron‐Transfer Barriers for Zinc Oxide/C60 Fullerene Interfaces

The interfacial electronic structure between oxide thin films and organic semiconductors remains a key parameter for optimum functionality and performance of next‐generation organic/hybrid electronics. By tailoring defect concentrations in transparent conductive ZnO films, we demonstrate the importance of controlling the electron transfer barrier at the interface with organic acceptor molecules such as C₆₀. A combination of electron spectroscopy, density functional theory computations, and device characterization is used to determine band alignment and electron injection barriers. Extensive experimental and first principles calculations reveal the controllable formation of hybridized interface states and charge transfer between shallow donor defects in the oxide layer and the molecular adsorbate. Importantly, it is shown that removal of shallow donor intragap states causes a larger barrier for electron injection. Thus, hybrid interface states constitute an important gateway for nearly barrier‐free charge carrier injection. These findings open new avenues to understand and tailor interfaces between organic semiconductors and transparent oxides, of critical importance for novel optoelectronic devices and applications in energy‐conversion and sensor technologies.     

Optical communication and fiber design

Optical fiber has evolved from a not-so-transparent glass tube to an extraordinarily efficient transmission medium. It is now acknowledged as a central element of modern telecommunication being part of the whole optimization process to further improve transmission system performance and cost. In this paper, we briefly introduce transmission system optimization problematics as well as key fiber characteristics. We then review the elements of fiber design for optimized optical communication networks, including metropolitan, long and ultra-long haul applications and show how fibers have evolved over the last ten years to keep pace with more and more demanding requirement of transmission system.     

Articulated hybrid mobile robot mechanism with compounded mobility and manipulation and on-board wireless sensor/actuator control interfaces

This paper presents the development of a remotely operated mobile robot system with a hybrid mechanism whereby the locomotion platform and manipulator arm are designed as one entity to support both locomotion and manipulation interchangeably. The mechanical design is briefly described as well as the dynamic simulations used to analyze the robot mobility and functionality. As part of the development, this paper mainly focuses on a new generalized control hardware architecture based on embedded on-board wireless communication network between the robot’s subsystems. This approach results in a modular control hardware architecture since no wire connections are used between the actuators and sensors in each of the mobile robot subsystems and also provides operational fault-tolerance. The effectiveness of this approach is experimentally demonstrated and validated by implementing it in the hybrid mobile robot system. The new control hardware architecture and mechanical design demonstrate the qualitative and quantitative performance improvements of the mobile robot in terms of the new locomotion and manipulation capabilities it provides. Experimental results are presented to demonstrate new operative tasks that the robot was able to accomplish, such as traversing challenging obstacles, and manipulating objects of various capacities; functions often required in various challenging applications, such as search and rescue missions, hazardous site inspections, and planetary explorations.     

Ultrathin PECVD epitaxial Si solar cells on glass via low‐temperature transfer process

Fabrication of high‐quality ultrathin monocrystalline silicon layers and their transfer to low‐cost substrates are key steps for flexible electronics and photovoltaics. In this work, we demonstrate a low‐temperature and low‐cost process for ultrathin silicon solar cells. By using standard plasma‐enhanced chemical vapor deposition (PECVD), we grow high‐quality epitaxial silicon layers (epi‐PECVD) from SiH₄/H₂ gas mixtures at 175 °C. Using secondary ion mass spectrometry and transmission electron microscopy, we show that the porosity of the epi‐PECVD/crystalline silicon interface can be tuned by controlling the hydrogen accumulation there. Moreover, we demonstrate that 13–14% porosity is a threshold above which the interface becomes fragile and can easily be cleaved. Taking advantage of the H‐rich interface fragility, we demonstrate the transfer of large areas (∽10 cm²) ultrathin epi‐PECVD layers (0.5–5.5 µm) onto glass substrates by anodic bonding and moderate annealing (275–350 °C). The structural properties of transferred layers are assessed, and the first PECVD epitaxial silicon solar cells transferred on glass are characterized. Copyright © 2016 John Wiley & Sons, Ltd.     

Nanoparticle probes and mid-infrared chemical imaging for DNA microarray detection

To date most mid-infrared spectroscopic studies have been limited, due to lack of sensitivity, to the structural characterization of a single oligonucleotide probe immobilized over the entire surface of a gold-coated slide or other infrared substrate. By contrast, widely used and commercially available glass slides and a microarray spotter that prints approximately 120-μm-diameter DNA spots were employed in the present work. To our knowledge, mid-infrared chemical imaging (IRCI) in the external reflection mode has been applied in the present study for the first time to the detection of nanostructure-based DNA microarrays spotted on glass slides. Alkyl amine-modified oligonucleotide probes were immobilized on glass slides that had been prefunctionalized with succinimidyl ester groups. This molecular fluorophore-free method entailed the binding of gold-nanoparticle-streptavidin conjugates to biotinylated DNA targets. Hybridization was visualized by the silver enhancement of gold nanoparticles. The adlayer of silver, selectively bound only to hybridized spots in a microarray, formed the external reflective infrared substrate that was necessary for the detection of DNA hybridization by IRCI in the present proof-of-concept study. IRCI made it possible to discriminate between diffuse and specular external reflection modes. The promising qualitative results are presented herein, and the implications for quantitative determination of DNA microarrays are discussed.