A Novel (DDCC-SFG)-Based Systematic Design Technique of Active Filters

This paper proposes a novel idea for the synthesis of active filters that is based on the use of signal-flow graph (SFG) stamps of differential difference current conveyors (DDCCs). On the basis of an RLC passive network or a filter symbolic transfer function, an equivalent SFG is constructed. DDCCs’ SFGs are identified inside the constructed ‘active’ graph, and thus the equivalent circuit can be easily synthesized. We show that the DDCC and its ‘derivatives’, i.e. differential voltage current conveyors and the conventional current conveyors, are the main basic building blocks in such design. The practicability of the proposed technique is showcased via three application examples. Spice simulations are given to show the viability of the proposed technique

A novel design of active inductors based on current controlled voltage sources

This brief presents a new structure of active inductors. These synthetic inductors are designed using current controlled voltage sources. The signal flow graph method is used for this purpose. For the practical realization, operational transresistance amplifiers (OTRAs) are replicated using current conveyors. The proposed inductors have very interesting properties because the value of its inductance is proportional to the product of the parameter of the OTRAs (rm1rm2) and thus, small capacitor values can be used. Current conveyor based simulated inductors are presented and SPICE simulations are given to show the viability of the proposed synthesis technique. ©2010 IEEE

Process diagnosis with timed observation

International audienceIn this paper we propose the use of the Timed Observation theory as a powerful frameworks for model-based diagnosis. In fact, they provide a global formalism for modelling a dynamic system (TOM4D), for characterizing and computing diagnoses of the system under investigation

Toward a decompositional and incremental approach to diagnosis of dynamic systems from timed observations

International audienceIt is now well-known that the size of the model is the bottleneck when using model-based approaches to diagnose complex systems. To answer this problem, decompositional and multi modelling approaches have been proposed. In this paper, we propose a multi-modelling method called TOM4D (Timed Observations Modelling for Diagnosis) able to cope with dynamic aspects. It relies on four models: perception, structural, functional and behaviour models. The behaviour model is described through system component models as a set of component behaviour models and the global diagnosis is computed from the component diagnoses (also called local diagnoses). Another problem, which is far less considered, is the size of the diagnosis itself. However, it can also be huge enough, especially when dealing with dynamic system. To solve this problem, we propose in this paper to use The Timed Observation Theory. In this context, we characterize the diagnosis using TOM4D and the timed observation theory. We show their relevance to get a tractable representation of diagnosis. To illustrate the impact on the diagnosis size, experimental results on a hydraulic example are given

Modelling and diagnosis of dynamic systems from timed observations

International audienceThis paper proposes the use of the Timed Observation theory as a powerful framework for model-based diagnosis. In fact, this theory provides a global formalism for modelling a dynamic system (TOM4D), for characterizing and computing diagnoses of the system under investigation

Pathotypic diversity of Rhynchosporium secalis (Oudem) in Tunisia

Scald, caused by Rhynchosporium secalis (Oudem), is an important disease of barley in Tunisia particularly in northern, northwestern and central parts of the country where the climate is usually cold and wet during most of the barley growing season. Pathogenic variability of the barley scald pathogen in Tunisia was determined by testing the pathogenicity of 100 isolates from 5 different regions on 19 host differentials. Pathotypic diversity was high, with 93 R. secalis pathotypes identified on two differential sets (one comprising 9 and the other 10 barley lines) containing known resistance genes. A few pathotypes comprised 2% of the isolates; however, the majorities were represented by a single isolate. None of the differential lines was resistant to all isolates. The differential cultivar “Astrix” was the least compatible with the scald pathotypes followed by the differential cultivars “Atlas” and “Abyssinia”. Compatibility of the pathotypes on “Rihane” (69%) was close to that on “Osiris” (73%) and “La Mesita” (61%). None of the pathotypes was found in all the five regions of Tunisia surveyed. Some pathotypes were specific to a single region while others were found in several regions. The incidence of pathotypes varied considerably among regions, with region 3 (northwestern Tunisia) comprising the largest number of pathotypes. Virulent pathotypes were recovered in all regions but more pathotypic variability (44%) was observed in the semi-arid region 3. Differential cultivars allowed classification of R. secalis in four virulence groups. Canonical discriminant analysis showed no apparent association between virulence and geographical origin of the populations. Pathogenic variability in R. secalis in Tunisia was found not to be associated with geographical region, hence, the necessity for deployment of different resistance sources in major barley growing areas.Key words: Rhynchosporium secalis, barley, virulence groups, pathotypic variation

Analyzing Recent Coronary Heart Disease Mortality Trends in Tunisia between 1997 and 2009.

BACKGROUND: In Tunisia, Cardiovascular Diseases are the leading causes of death (30%), 70% of those are coronary heart disease (CHD) deaths and population studies have demonstrated that major risk factor levels are increasing. OBJECTIVE: To explain recent CHD trends in Tunisia between 1997 and 2009. METHODS: DATA SOURCES: Published and unpublished data were identified by extensive searches, complemented with specifically designed surveys. ANALYSIS: Data were integrated and analyzed using the previously validated IMPACT CHD policy model. Data items included: (i)number of CHD patients in specific groups (including acute coronary syndromes, congestive heart failure and chronic angina)(ii) uptake of specific medical and surgical treatments, and(iii) population trends in major cardiovascular risk factors (smoking, total cholesterol, systolic blood pressure (SBP), body mass index (BMI), diabetes and physical inactivity). RESULTS: CHD mortality rates increased by 11.8% for men and 23.8% for women, resulting in 680 additional CHD deaths in 2009 compared with the 1997 baseline, after adjusting for population change. Almost all (98%) of this rise was explained by risk factor increases, though men and women differed. A large rise in total cholesterol level in men (0.73 mmol/L) generated 440 additional deaths. In women, a fall (-0.43 mmol/L), apparently avoided about 95 deaths. For SBP a rise in men (4 mmHg) generated 270 additional deaths. In women, a 2 mmHg fall avoided 65 deaths. BMI and diabetes increased substantially resulting respectively in 105 and 75 additional deaths. Increased treatment uptake prevented about 450 deaths in 2009. The most important contributions came from secondary prevention following Acute Myocardial Infarction (AMI) (95 fewer deaths), initial AMI treatments (90), antihypertensive medications (80) and unstable angina (75). CONCLUSIONS: Recent trends in CHD mortality mainly reflected increases in major modifiable risk factors, notably SBP and cholesterol, BMI and diabetes. Current prevention strategies are mainly focused on treatments but should become more comprehensive

INTERFACIAL RELAXATION IN SEMI-CRYSTALLINE POLYMER

Abstract The semi-crystalline morphology of a series of poly(ether ether ketone) (PEEK) has been investigated as a function of crystallization condition by dielectric relaxation spectroscopy. An interfacial polarization effect, known as the Maxwell-Wagner-Sillars polarization, is clearly evident taking place at the interface between the crystalline inclusions and the amorphous matrix. The intensity of the relaxation is presented in relation to the morphology of the crystalline part which is known to depend on annealing conditions