A Compositional Behavioral Modeling Framework for Embedded System Design and Conformance Checking

We propose a framework based on a synchronous multi-clocked model of computation to support the inductive and compositional construction of scalable behavioral models of embedded systems engineered with de facto standard design and programming languages. Behavioral modeling is seen under the paradigm of type inference. The aim of the proposed type system is to capture the behavior of a system under design and to re-factor it by performing global optimizing and architecture-sensitive transformations on it. It allows to modularly express a wide spectrum of static and dynamic behavioral properties and automatically or manually scale the desired degree of abstraction of these properties for efficient verification. The type system is presented using a generic and language-independent static single assignment intermediate representation.     

Ultrasonic ranging sensor using simultaneous emissions from different transducers

In recent applications based on ultrasound, several ultrasonic transducers have been geometrically and electronically associated to constitute a global sensor. There are several different methods used to process the ultrasonic signals obtained from these transducers. In this work, multimode techniques using Golay complementary sequences are proposed for processing the ultrasonic signal. The system increases scan rate, precision, and reliability. It is also capable of echo discrimination, allowing simultaneous measurements to be made and detection of the same obstacle by different transducers without cross-talk problems. The real-time implementation of the algorithm is presented on a field-programmable gate array (FPGA) device.     

Community-based school feeding during Indonesia's economic crisis: implementation, benefits, and sustainability

The Indonesian Government initiated a community-based national school-feeding program in 1996. Implementation was decentralized and involved multiple participants. In 1998 we evaluated the implementation of the program and the perceived benefits for community stakeholders using a survey of principals in 143 randomly selected schools and follow-up with in-depth interviews and observations in a subsample of 16 communities. The evaluation covered the period of the 1998 Asian economic crisis, affording the opportunity to assess its impact on the program. The program was implemented in all targeted schools, with excellent community participation. Feeding was sustained through the crisis, in spite of a dramatic escalation in food costs. The families of schoolchildren, farmers, and those who prepared food received economic benefits. The snacks replaced those sold at schools and were of better nutritional value. The children benefited because the snacks compensated for losses in the home diet resulting from the economic crisis. Characteristics of the program that may be important in explaining its success include the involvement of a range of community stakeholders, engagement with existing village administrative structures, scope for local community adaptation and innovation, and the use of local foods that dispersed benefits and ensured sustained implementation during the crisis.     

Tolerance and starvation induced cross-protection against different stresses in Aeromonas hydrophila

Aeromonas hydrophila is sometimes considered as a controversial human pathogen and reported to be susceptible to food processing procedures and environmental stresses. In this study, we have shown that early stationary phase cells of A. hydrophila were readily killed during up shifts in temperature (in the range 50-70 degrees C), the course of drying (at relative humidity, temperature and brightness of the laboratory) and after 5 min exposure to 20%, 30% and 40% v/v ethanol. However, this bacterium was found moderately susceptible to down shift to 4 degrees C in nutrient poor water, sodium chloride stresses (1.5 and 2 M) and to 12% and 15% v/v ethanol stresses. Tolerance against 1 M NaCl and 10% v/v ethanol was observed. At ambient temperature (24.5 degrees C), this microorganism exhibited a starvation survival state, which was largely independent of the initial cell concentrations (8.82, 7.71 and 6.76 log units). The cross-protection experiments showed that cells starved for short (1 day) or prolonged (50 days) periods developed increased resistance to down shift at 4 degrees C and ethanol stress. This may be of concern to the food-processing industry from the public health perspective.     

Two-wavelength, passive self-injection-controlled operation of diode-pumped cw Yb-doped crystal lasers

We demonstrate and investigate a peculiar mode of cw Yb3+-doped crystal laser operation when two emissions, at two independently tunable wavelengths, are simultaneously produced. Both emissions are generated from a single pumped volume and take place in either a single beam or spatially separated beams. The laser employs original two-channel cavities that use a passive self-injection-locking (PSIL) control to reduce intracavity loss. The advantages of the application of the PSIL technique and some limitations are shown. The conditions for two-wavelength multimode operation of the cw quasi-three-level diode-pumped Yb3+ lasers and the peculiarity of such an operation are carried out both theoretically and experimentally. The results reported are based on the example of a Yb3+:GGG laser but similar results are also obtained with a Yb3+:YAG laser. The laser operates in the 1023-1033-nm (1030-1040-nm) range with a total output power of 0.4 W. A two-wavelength, single longitudinal mode generation is also obtained.     

Comparison of 127I2-stabilized frequency-doubled Nd:YAG lasers at the Bureau International des Poids et Mesures

A frequency comparison was carried out between iodine-stabilized Nd:YAG lasers at 532 nm from the Bureau International des Poids et Mesures, the Centre for Metrology and Accreditation, the Czech Metrology Institute, and the Bureau National de Métrologie-Institut National de Métrologie. The frequency differences between lasers, as well as the frequency reproducibility of each system,were investigated. Pressure-, modulation-, and power-induced shifts were studied. A frequency dispersion (1 sigma) of 3.5 kHz (6.2 x 10(-12) in relative terms) with an average reproducibility for each laser of the order of 0.4 kHz (7.1 x 10(-13) in relative terms) was observed over the duration of the comparison. Relative stabilities better than 1 x 10(13) at 1 s were demonstrated for the third-harmonic systems.     

Thermoelectric microdevice fabricated by a MEMS-like electrochemical process

Microelectromechanical systems (MEMS) are the basis of many rapidly growing technologies, because they combine miniature sensors and actuators with communications and electronics at low cost. Commercial MEMS fabrication processes are limited to silicon-based materials or two-dimensional structures. Here we show an inexpensive, electrochemical technique to build MEMS-like structures that contain several different metals and semiconductors with three-dimensional bridging structures. We demonstrate this technique by building a working microthermoelectric device. Using repeated exposure and development of multiple photoresist layers, several different metals and thermoelectric materials are fabricated in a three-dimensional structure. A device containing 126 n-type and p-type (Bi, Sb)2Te3 thermoelectric elements, 20 microm tall and 60 microm in diameter with bridging metal interconnects, was fabricated and cooling demonstrated. Such a device should be of technological importance for precise thermal control when operating as a cooler, and for portable power when operating as a micro power generator.     

Photo-oxydation d'elastomères EPDM et EPM en présence de systèmes photosensibles, 3. Rôle de la benzophénone à l'etat greffé

Quantitative measurements and calculation of quantum yields have been achieved about photo-oxidation at λ = 313 nm of a poly[ethylene-co-propene-co(1,4-hexadiene)] (EPDM) grafted with low amounts of benzophenone groups. First, an appropriate comparison with blended systems reveals that grafting of photosensitizer enhanced preferentially the extend of formation of oxidation products and chain scissions with respect to crosslinking. From a second comparison with another grafted system, i.e. a phenylated EPDM, it is deduced that propagation of inactive hydroperoxides depends strongly on the nature of involved photosensitive groups.     

Bistabilité, multistabilité et chaos en longueur d’onde

Unstable and chaotic phenomena have lead to a number of studies in the area of optics which allows easy experimental verifications owing to the use of optical sources and feedback, and optically-induced non linearities. Most of those studies have dealt with hybrid or all-optical systems working in monochromatic light and whose dynamic variable of concern was the energy. The work presented here deals with chaotic phenomena linked to the wavelength variable. The latter opens up new possibilities inherent to the high flexibility in inducing wavelength non linearities and their control, and to the greater dynamic excursion of the signals. Wavelength bistable and multistable devices are presented, together with a discussion of the various routes to chaos they can generate. The prospects given in the conclusion deal with the use of the wavelength variable in a chaos generator, the multivalued coding in wavelength of signals, and the chaos that would be generated by a system with a feedback featuring a signal-dependent optical delay.