Planar p-on-n HgCdTe FPAs by Arsenic Ion Implantation

This paper reviews recent developments in the characterization of planar p-on-n photodiodes fabricated from long- and mid-wavelength Hg_1−x Cd _x Te at␣the Electronics and Information Technology Laboratory (LETI). The Hg_1−x Cd _x Te epitaxial layers were grown by both liquid-phase and molecular-beam epitaxy. Planar p-on-n photodiodes were fabricated by arsenic implantation into an indium-doped Hg_1−x Cd _x Te base layer. Electro-optical characterization on these p-on-n photodiodes showed low leakage currents (shunt resistance > 10 GΩ) and mean R ₀ A values comparable to the state of the art, i.e., equal to 5000 Ω cm² at λ _c = 9.3 μm (λ _c: cutoff wavelength). Results of focal-plane arrays operating in both the long-wavelength infrared (IR) and middle-wavelength IR bands are reported, with noise equivalent delta temperature and responsivity values at λ _c = 9.3 μm in excess of 99.64%. These results demonstrate the viability and technological maturity of both material growth and device processing.     

Wet Etching of HgCdTe in Aqueous Bromine Solutions: a Quantitative Chemical Approach

The ability to pattern HgCdTe surfaces using a wet etching solution is an important challenge for processing of third-generation infrared detectors. The reduction of pixel size, the increase of pixel density, and two-color array technology require perfectly mastered etching to remove very thin layers and to control the state of the surface. To perform this process, a new quantitative chemical approach was developed to carry out very accurate wet etching in aqueous HBr/Br₂ solutions. This approach was established to identify the key parameters that govern the etching process and to understand the etching mechanism.     

Foundations of a new software engineering method for real-time systems

The design of a fault-tolerant distributed, real-time, embedded system with safety-critical concerns requires the use of formal languages. In this paper, we present the foundations of a new software engineering method for real-time systems that enables the integration of semiformal and formal notations. This new software engineering method is mostly based upon the ”COntinuuM” co-modeling methodology that we have used to integrate architecture models of real-time systems (Perseil and Pautet in 12th International conference on engineering of complex computer systems, ICECCS, IEEE Computer Society, Auckland, pp 371–376, 2007) (so we call it “Method C”), and a model-driven development process (ISBN 978-0-387-39361-2 in: From model-driven design to resource management for distributed embedded systems, Springer, chap. MDE benefits for distributed, real time and embedded systems, 2006). The method will be tested in the design and development of integrated modular avionics (IMA) frameworks, with DO178, DO254, DO297, and MILS-CC requirements.     

Toward nex-generation middleware?

A large range of application domains, from real-time embedded systems to grid-computing applications, now requires distribution. This trend implies definitions of new or tailored distribution mechanisms dedicated to specific applications and puts a strain on current middleware architectures and development. Middleware intends to separate an application from variations in hardware and operating systems. This new interoperability problem itself is serious industrial issue. We call this the middleware paradox. Next-generation middleware should be versatile enough to instantiate the exact required mechanisms of different distribution models. Middleware components that depend on a specific distribution model should be limited to application-level components or to protocol-level components.     

Formal methods integration in software engineering

This paper presents an extract from our works on a software engineering method for avionic real-time systems [3], the C-Method, which covers the whole software lifecycle thanks to a seamless process, and integrates formal methods in its process. Because distributed, real-time and embedded (DRE) systems have safety critical concerns, they require the use of formal languages (that allow non-ambiguous and rigorous specifications) in order to be able to prove their non-functional properties. Therefore, the “C-Method” relies on the use of formal languages in the earliest steps of the system specification and on the use of semi-formal languages in the analysis, design and programming steps. The fundamental question is how to integrate several languages with different levels of formalization and abstraction. The previous software engineering methods were based on a single language or notation, so they did not address this issue. In order to make the transitions more continuous between semi-formal and formal specifications, we have introduced in the development process what we call “intermediate” languages (+CAL and Why), that are easy to manipulate but directly linked to a formal language (TLA+ for +CAL, Why for PVS).     

Competition between isomerization and addition in the Sonication of Vinyl Sulfones in the presence of bromotrichloromethane

(E)- and (Z)-vinyl sulfones isomerise under ultrasound irradiation in carbon tetrachloride in the presence of bromoform or bromotrichloromethane to give an E/Z equilibrium mixture via bromine radicals. Furthermore, the bromine radicals formed add to the CC double bond (presumably of the Z isomer) to form vic-dibromo compounds. In pure CBrCl₃ this addition reaction reaches a 99% yield. In tetrahydrofurane/CBr₄ (or CBrCl₃) no isomerization is observed since the bromine radicals react probably with the THF. The addition is also favoured by highly efficient energy transmission.     

Multi-objective exploration of architectural designs by composition of model transformations

Software and Systems Modeling - Designing software architectures and optimizing them based on extra-functional properties (EFPs) require to identify appropriate design decisions and to apply them...     

Work-conserving dynamic time-division multiplexing for multi-criticality systems

Real-Time Systems - Multi-core architectures pose many challenges in real-time systems, which arise from contention between concurrent accesses to shared memory. Among the available memory...     

Three-dimensional tomographic reconstruction of mesospheric airglow structures using two-station ground-based image measurements

A new methodology is presented to create two-dimensional (2D) and three-dimensional (3D) tomographic reconstructions of mesospheric airglow layer structure using two-station all-sky image measurements. A fanning technique is presented that produces a series of cross-sectional 2D reconstructions, which are combined to create a 3D mapping of the airglow volume. The imaging configuration is discussed and the inherent challenges of using limited-angle data in tomographic reconstructions have been analyzed using artificially generated imaging objects. An iterative reconstruction method, the partially constrained algebraic reconstruction technique (PCART), was used in conjunction with a priori information of the airglow emission profile to constrain the height of the imaged region, thereby reducing the indeterminacy of the inverse problem. Synthetic projection data were acquired from the imaging objects and the forward problem to validate the tomographic method and to demonstrate the ability of this technique to accurately reconstruct information using only two ground-based sites. Reconstructions of the OH airglow layer were created using data recorded by all-sky CCD cameras located at Bear Lake Observatory, Utah, and at Star Valley, Wyoming, with an optimal site separation of ~100 km. The ability to extend powerful 2D and 3D tomographic methods to two-station ground-based measurements offers obvious practical advantages for new measurement programs. The importance and applications of mesospheric tomographic reconstructions in airglow studies, as well as the need for future measurements and continued development of techniques of this type, are discussed.