An adaptive CFAR embedded system architecture for target detection

This paper presents field-programmable gate array (FPGA)-based novel forward and backward automatic censored cell algorithms using a Nios II core processor embedded on a Stratix II FPGA programmable device. These algorithms were recently presented for target detection in a nonhomogeneous environment, and they operate in a complementary manner to allow for high-resolution target detection with a time constraint fixed below 0.5 μs. The ACOSD-based constant false alarm rate detector does not require any prior information regarding the background environment and employs statistical analysis to dynamically calculate the threshold at which the ordered cells under investigation are accepted or rejected. The advantages of the proposed system lie in its simplicity and short processing time while maintaining a low development cost. For a reference window of 16 range cells, the experimental results obtained using the Stratix II development kit demonstrate that the proposed architecture works properly with a processing speed of 100 MHz and an overall detector execution time of 0.11 μs for each range cell. The designed hardware, which is an example of system-on-chip architecture, was physically realized in a Stratix II FPGA device, and the results are presented and discussed.     

In situ-based assessment of soil liquefaction potential–Case study of an earth dam in Tunisia

The present paper examines the evaluation of liquefaction potential of an earth dam foundation in Tunisia. The assessment of soil liquefaction was made using deterministic and probabilistic simplified procedures developed from several case histories. The data collected from the field investigation performed before and after the vibrocompaction are analyzed and the results are reported. The obtained results show that after vibrocompaction, a significant improvement of the soil resistance reduces the liquefaction potential of the sandy foundation. Indeed, in the untreated layers, the factor of safety FS drops below 1 which means that the soil is susceptible for liquefaction. However, in the compacted horizons, the values of FS exceed the unit which justifies the absence of liquefaction hazard of the foundation.     

Taguching the Atmospheric Plasma Spraying Process: Influence of Processing Factors on Droplet Impact Properties Obtained on Dense ZrO₂ and H₂Ar75% Plasma Gas

In this paper a study of the atmospheric plasma spraying process was conducted. The Jets&Poudres code was used to solve the partial differential equations for the conservation of mass, momentum and energy involved in the problem together with the K-e turbulent model. The Taguchi technique was used to study the influence of processing factors on droplet impact properties obtained on dense zirconia (ZrO₂) under H₂Ar75% plasma gas that allow optimal functioning condition. The test of the operating parameters for the studied ranges showed that the "thermal power" factor plays a key role on the state of sprayed powder. It was found also that the carrier gas flow rate and the powder size do not influence the dispersion of the impact behavior of droplets/particles. The validation of the chosen levels combination was conducted on the Jets&Poudres code and showed good agreement with the results predicted by the Taguchi technique.     

Extension of the anaerobic digestion model No. 1 (ADM1) to include phenolic compounds biodegradation processes for the simulation of anaerobic co-digestion of olive mill wastes at thermophilic temperature

This paper describes for the first time the extension of the anaerobic digestion model No. 1 (ADM1) to handle and simulate the anaerobic degradation processes of phenol compounds and homologues in olive mill wastewater (OMW) and olive mill solid waste (OMSW) at thermophilic temperature (55 degrees C). The general structure of the ADM1 was not changed except for the modifications related to the inclusion of phenolic compounds degradation processes into acetate and further into methane and CO(2). The effect of soluble phenolic compounds upon pH was taken into account in the pH simulation equations. The inhibitory effect of phenolic compounds on the fermenting process and methanogenic sub-populations was accounted for by the use of non-competitive inhibition functions. The most sensitive and new phenolic parameters were calibrated and validated using experimental data from our previous study dealing with the thermophilic anaerobic co-digestion of OMW with OMSW in semi-continuous tubular digesters. The simulation results indicated that the extended ADM1 was able to predict with reasonable accuracy effluent phenol concentrations and gas flow rates and effluent pH of various influent concentrations digested at hydraulic retention times (HRTs) of 36 and 24 days.     

Opportunistic Routing Protocols in Wireless Sensor Networks

Wireless Personal Communications - Research on wireless sensor network (WSN) has mainly involved the use of a portable and limited power source, namely batteries, to power the sensors. Without...     

Phenolic composition, isolation, and structure of a new deoxyloganic acid derivative from Dhokar and Gemri-Dhokar olive cultivars

Two rare olive cultivars, Dhokar and Gemri-Dhokar, growing in the south of Tunisia were investigated to identify their phenolic profile and evaluate their sugar content and antioxidant activity. The highest value of phenolic content was detected in Gemri-Dhokar cultivar extract (6.97 g gallic acid equivalents/kg of fresh olive). In addition, sugar content was quantified; glucose (45.17 g/kg of fresh olive) was the predominant sugar in Dhokar cultivar, followed by fructose (40.83 g/kg of fresh olive). The identification of phenolic compounds was based on separation by high-performance liquid chromatography equipped with a diode array detector followed by liquid chromatography-mass spectrometry analysis. In both cultivars, Oleuropein aglycon derivatives and elenolic acid were the main phenolic components. Oleuropeins were the major compounds quantified in the Gemri-Dhokar drupes olives (61.04 mg/100 g of fresh olive), while 0.25 mg/100 g were found in fresh Dhokar. A new iridoid compound, isolated as pure compound, was not previously reported in the literature. Its structure was established by spectroscopic analyses (NMR, UV, MS, and IR). DPPH, ABTS, and FRAP assays showed that the most important antioxidant capacity of olive extracts was found in with Gemri-Dhokar cultivar.     

Catalyse redox homogene de reduction des p-toluenesulfonamides. Determination des parametres cinetiques et thermodynamiques

The redox catalysis of the reduction of tertiary p-toluenesulfonamides and gem-N-di-p-toluenesulfonamides by electrogenerated organic anion radicals, on mercury cathode, was studied by cyclic voltammetry and controlled-potential electrolysis in aprotic DMF. Tertiary tosylamides, not directly reducible by electrochemical means in presence of LiClO₄ as a supporting electrolyte, were cleaved by electrogenerated pyren anion radical. The new theoretical treatments, recently developed by Savéant and coworkers and extended to a SET-type mechanism and cyclic voltammetry results, allowed us to determine the rate controlling step of the catalytic process and to calculate the standard rate constant of the homogeneous electron transfer reaction and the standard potential in respect to the tosylamide anion radical formation.     

An optimization strategy based on a metamodel applied for the prediction of the initial blank shape in a deep drawing process

The transformation of the sheet into a product without failure and excess of material in a deep drawing operation means that the initial blanks should be correctly designed. Therefore, the initial blank design is a critical step in deep drawing design procedure. Consequently, an easy approach for engineers in predicting the initial blank shape is necessary to reduce wastage in material and to overcome the large time consumed in the classical approaches. Thus, the aim of the present investigation is to propose an automatic procedure for the quick sheet metal forming optimization. In fact, a metamodel will be build based on artificial neural networks which will be coupled then with an optimization procedure in order to predict the initial blank shape in a rectangular cup deep drawing operation. The metamodel is built from the finite element simulations using ABAQUS commercial code. This procedure allows a significant reduce of the CPU time compared to classical optimization one. The results show that the desired shape is in good agreement with the one calculated using the optimized blank shape.     

Sliding wear transition for the CW614 brass alloy

Dry sliding wear tests were performed on a CW614 brass alloy using a pin-on-ring configuration. Wear kinetics were measured within a load range of 20–80 N and sliding velocity ranging from 1 to 7 m/s. Chemical compositions, morphologies and microstructures of worn surfaces and wear debris were characterised by scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS). Two main wear regimes have been observed: severe wear and mild wear. The results of wear tests and metallographic investigations on worn surfaces have been summarised in a wear mechanism map. It was found that the wear transition is controlled by a critical temperature at the contact surface.     

Effects of cyclic torsional prestraining and overstrain on fatigue life and damage behavior of brass alloy

Many practical structural members and parts may be subjected to fluctuating plastic deformation by prestraining due to manufacturing and machining process (forming operation, straightening, etc.) and unintentional overstrains (misuse, accidents, under design, etc.). For this reason, the effect of the prestrain and periodic overstrains on fatigue life and damage behavior was being necessary considered for reasonable fatigue design. In this context, an experimental program was conducted to study the effects of overstrain and prestraining on fatigue life and damage behavior of brass alloy subjected to cyclic torsional loading. To establish baseline fatigue behavior, several virgin specimens were tested under fully-reversed strain control and constant amplitude fatigue torsional loading up to failure. The obtained experimental results showed that the fatigue life depends strongly on the strain amplitude and prestraining type (monotonic or cyclic). In addition, a beneficial effect in the fatigue life was observed for all tests with periodic overstrain. Cyclic fatigue fracture on a macroscopic scale revealed features reminiscent of locally ductile and brittle mechanisms. At the same time, microscopic analysis indicated a difference on fatigue fracture surface morphology between the conducted tests and those performed under constant amplitude loading.