Extraction des lésions dans des images de scanner cérébral pour système de télédiagnostic

Cancer is one of the most widespread diseases in the world. Researchers thought of carrying out systems that will be the assistance tools for the decision and diagnosis to the doctors. The setting on network of such systems permits to have an application of tele-diagnosis, the goal is to bring « a second opinion » by a distant specialist to validate or invalidate the diagnosis established by the local expert, or to help this latter in making a correct diagnosis. To design such systems, several aspects are to dealt with. One of the most significant aspects is the problem of the big size of the medical images compared to the transmission flow. For that, in the case of the cerebral cancer, we propose to design a stage for extracting the lesions, its role is extracting the lesion with the respect of its size, its shape and its position. Since, the size of images to be sent decreases, because they are in two grey levels (black and white). The second goal of this stage is to simplify the image for the doctor with preserve all morphological characteristics of the lesions. For that, we can proceed by two manners, by extracting the edges of the lesion, or extracted all its areas. We use algorithms based on mathematical morphology operators, promising results were obtained, that permits to the doctor to begin the diagnosis step in a sure manner in local or distant areas. In this paper, we present mainly our tele-diagnosis system and the various algorithms used for designing the stage of lesion extraction.     

Simulation of PV-Wind-hybrid systems combined with hydrogen storage for rural electrification

Since many years, engineering, research and development of hybrid systems for rural electrification are strongly supported by computer simulations. Different software packages have been used according to the required level of details along with the progress of the project HYRESS. For the development of optimal system control and load/energy management strategy, different simulation models from APL (Alternative Power Library) have been used for a Hybrid PV-wind-hydrogen system that will be installed in the Essaouira region in Morocco. This library provides models developed by IWES for the simulation of regenerative power supply systems and it is used to investigate the integration of a hydrogen storage path in hybrid system operation.     

Recent seismicity of Central High Atlas and Ouarzazate basin (Morocco)

The paper describes the tectonic evolution of the Central High Atlas and the Ouarzazate basin in Morocco, noting that many of the tectonic phenomena follow the previous structural lines. Although the area is one of relatively low seismicity, its location in an intra plate part of the African Plate and its high morphology, the effects of an earthquake could be considerable. This study combines seismic records from 1900 to 2007 with the integration of existing tectonic and structural information to better define the seismogenic zones. A newly identified cluster of epicenters in a NNW-SSE linear zone may be related to the Imilchil fault, where the earthquakes with magnitudes of 4–5 at depths of 5–20 km have been identified. Recent work in the Ouarzazate basin indicated that the Amekchoud fault ramp could generate seismic events with magnitudes as large as 6.4 Mw.     

Physical and analytical modelling of geosynthetic strip pull-out behaviour

The design methods used for soil mass structures, such as mechanically stabilised earth (MSE) structures, are based on soil/reinforcement anchorage models which require the knowledge of the soil/reinforcement interface friction capacity. However, different types of reinforcements are used in these structures and present different behaviour. This study concerns two types of strips reinforcements. The first one is metallic and is classically designed using elasto-plastic models (21 and 22). The second type is geosynthetic. The classical anchorage models do not take into account the extensibility of this materiel and do not reproduce its complex behaviour.     

Characterization of oil including astaxanthin extracted from krill (Euphausia superba) using supercritical carbon dioxide and organic solvent as comparative method

Krill oil including astaxanthin was extracted using supercritical CO₂ and hexane. The effects of different parameters such as pressure (15 to 25MPa), temperature (35 to 45 °C), and extraction time, were investigated. The flow rate of CO₂ (22 gmin⁻¹) was constant for the entire extraction period of 2.5 h. The maximum oil yield was found at higher extraction temperature and pressure. The oil obtained by SC-CO₂ extraction contained a high percentage of polyunsaturated fatty acids, especially EPA and DHA. The acidity and peroxide value of krill oil obtained by SC-CO₂ extraction were lower than that of the oil obtained by hexane. The SC-CO₂ extracted oil showed more stability than the oil obtained by hexane extraction. The amount of astaxanthin in krill oil was determined by HPLC and compared at different extraction conditions. The maximum yield of astaxanthin was found in krill oil extracted at 25 MPa and 45 °C.     

Thermal-Hydraulic Characteristics of Helical Baffle Shell-and-Tube Heat Exchangers

Abstract

Shell-and-tube heat exchangers are frequently used in several industrial applications. A model was developed using engineering equations solver software to predict the performance of various baffle configurations of shell-and-tube heat exchangers. The model is based on the Bell-Delaware method for the segmental baffle, while mathematical correlations for the helical baffle are provided for design and analysis purpose. The accuracy of the present model is validated against the experimental data available in the literature. The results showed that helical baffles offer much higher performance compared to the segmental baffled heat exchanger. It was found that the performance of the helical baffle increases with increasing baffle angle until it reaches an optimum value; it then starts to decrease at an angle of 42°.     

Analysis of sliding and pressure distribution during arepositioning of persons in a simulator chair

This study was undertaken to investigate the effect of system tilt and back recline angles on sliding and pressure distribution of seated subjects. Ten able-bodied subjects adopted successively 12 postures on a multiadjustable simulator chair. The system tilt angle was varied from 0° to 45° posterior tilt, while the seat to back angle varied from 90° to 120°. A maximum of 40.2% of weight shift was found when combining a system tilt angle of 45° to a seat to back angle of 120°. Maximum value of 74 mm of sliding was observed for the acromion marker during repositioning. Significant weight shift at the level of the seat is obtained only when the system tilt angle exceeds 15° in a posterior direction. We can put forward here that a small tilt ⩽15° can be used to adjust back pressure distribution, whereas large posterior tilts are used for an effective weight shift at the seat level. The peak pressure gradient remains in general in the interval of ±30% from the neutral posture for the able-bodied subjects and is fairly constant at 15° of tilt. A significant amount of displacement along the back and seat reference plane were found for the shoulder and hip markers, but this displacement does not necessarily correspond to a pure translation motion of the pelvic segment     

Degradation assessment of LDPE multilayer films used as a greenhouse cover: Natural and artificial aging impacts

This article focuses on the assessment and understanding of the mechanism of natural and artificial aging processes of a triple‐layer film made of low‐density polyethylene (LDPE) used as greenhouse cover. The film material contains color dye and ultraviolet–A (UV–A) and infrared (IR) stabilizers and antioxidant. The combined effect of temperature variations and UV–A radiations, of the natural and artificial aging, on the physical properties (free surface energy and yellow color measurements), mechanical behavior (tensile tests), thermal stability (TGA and DSC analysis), and structural stability (FTIR analysis) was investigated. The natural aging was conducted on a greenhouse, located in northern Algeria, over a period of 7 months. However, the artificial aging was performed at four different agricultural greenhouse simulating conditions of temperature and UV–A radiation (namely, at 40°C, 40°C with UV–A, 50°C, and 50°C with UV–A) for periods of aging up to 5486 h (7.6 months). The results revealed that, the maximum loss of the yellow color additives occurs at 2981 h under the natural aging process and at 2440, 1096, 1340, and 121 h under the four artificial aging conditions, respectively. There was an observed increase in the films free surface energy and a significant degradation in the mechanical properties with aging time. This can be correlated with the film material structural changes. The natural aging of the film in North Africa is almost equivalent to artificial aging at 40°C. The concurrent effect of temperature and UV–A radiations induced polymer chains scission leading to faster degradation in the film material and consequently a reduction in its durability and service lifetime. The results show also that the measured parameters are directly related to the limit of use criterion for evaluating the lifespan of agricultural greenhouse LDPE covers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Short Palm Tree Fibers Polyolefin Composites: Effect of Filler Content and Coupling Agent on Physical Properties

Short date palm tree lignocellulosic fibers have been used as a reinforcing phase in commodity thermoplastic matrices [poly(propylene) and low density polyethylene]. Compatibilization of the fibers was carried out with the use of maleic anhydride copolymers. The morphology, thermal and mechanical properties of the resulting composites were characterized using SEM, DSC and tensile tests. The reinforcing capability of the unmodified fibers was found to depend on the nature of the matrix and the main parameter governing the composite behavior was the degree of crystallinity of the matrix. Compatibilization was reported to enhance the mechanical performances for both sets of composites up to a critical amount of compatibilizer beyond which the degree of crystallinity of the matrix decreases.