Simulink behavioral modeling of a 10-bit pipelined ADC

The increasing architecture complexity of data converters makes it necessary to use behavioral models to simulate their electrical performance and to determine their relevant data features. For this purpose, a specific data converter simulation environment has been developed which allows designers to perform time-domain behavioral simulations of pipelined analog to digital converters (ADCs). All the necessary blocks of this specific simulation environment have been implemented using the popular Matlab simulink environment. The purpose of this paper is to present the behavioral models of these blocks taking into account most of the pipelined ADC non-idealities, such as sampling jitter, noise, and operational amplifier parameters (white noise, finite DC gain, finite bandwidth, slew rate, and saturation voltages). Simulations, using a 10-bit pipelined ADC as a design example, show that in addition to the limits analysis and the electrical features extraction, designers can determine the specifications of the basic blocks in order to meet the given data converter requirements.     

Mechanical and interfacial properties of wood and bio-based thermoplastic composite

The aim of this investigation was to study a new family of wood polymer composites with thermoplastic elastomer matrix (pebax® copolymers) instead of commonly used WPC matrices. These copolymers are polyether-b-amide thermoplastic elastomers which present an important elongation at break and a melting point below 200 °C to prevent wood fibers degradation during processing. Moreover these polymers are synthesized from renewable resources and they present a hydrophilic character which allow them to interact with wood fibers. We have used two pebax® grade with different hardness and three types of wood fibers, so the influence of the matrix and wood fibers characteristics were evaluated. Composites were produced using a laboratory-size twin screw extruder to obtain composite pellets prior to injection moulding into tensile test samples. We have evaluated fibers/matrix interaction by differential scanning calorimetry (DSC), infrared spectroscopy (IRTF) and scanning electron microscopy (SEM). Then, the mechanical properties, through tensile test, were assessed. We also observed fibers dispersion into the matrix by tomography X. DSC, IRTF and SEM measurements confirmed the presence of strong interface interactions between polymer and wood. These interactions lead to good mechanical properties of the composites with a reinforcement effect of wood fibers due also to a good dispersion of fibers into the matrix without agglomerate.     

Indoor Mobile Robot Local Path Planner with Trajectory Tracking

This paper deals with the design and implementation of an indoor mobile robot local path planner. This latter is based essentially on an ultrasonic perception system, where the covered region of sight is widened and the apparent distance between any two adjacent sensors can be adjusted. So, good resolution can be obtained and laterally positioned obstacles with respect to the robot line of sight are well identified. Furthermore, we propose a technique to improve the odometric method, to reduce the systematic errors and to detect floor irregularities. Following a predefined trajectory is provided by the control of the trailing wheel deviation angle.     

Analog design-for-testability technique for first-order sigma delta ADC

In this paper, a design for testability of 10 bits continuous time sigma delta ADC is presented. This new full test technique provides: simple way, 2 external lines and high testability for the circuit’s performances. This test is used for different sub-circuits evaluation and characterization to determine the contribution of each part in the total ADC error thus the ADC design can be improved. Using standard CMOS 0.24 μm technology this technique is implemented, the obtained results confirm that the presented technique ensures a high ADC testability, and the suitability for use with integrated circuit (IC) post development design is demonstrated.     

Contribution to the modeling of a non-ideal Sigma-Delta modulator

One major issue facing the design and the simulation of complex circuits, such as Sigma-Delta modulators (ΣΔM), is the relatively large computing-time; required when using transistor level based simulators. Hence, high-level system modeling is suitable to achieve a time-efficient IC design. In this scope, the aim of the present work is to develop an enhanced model for a switched-capacitor second order sigma delta modulator. Besides the numerous effects, already included in the standard models, many additional non-idealities aspects have been taken into consideration. Namely, the DC nonlinearity behavior of both: the operational amplifier (OP-AMP) and the switches ON-resistance. The obtained model permits, thus, more accurate prediction of the relative signal-to-noise ratio (SNR), compared to the standard one.     

Lignin-based wood panel adhesives without formaldehyde

Lignin-based wood adhesives prepared without formaldehyde substituted by non-volatile non-toxic aldehyde, namely glyoxal, were prepared and tested for application to wood panels such as particleboard. The adhesives yielded good IB strength results of the panels, enough to comfortably pass relevant international standard specifications for exterior-grade panels. The adhesives also showed sufficient reactivity to yield panels in press times comparable to those of formaldehyde-based commercial adhesives.     

Peptide immobilisation on porous silicon surface for metal ions detection

In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis) peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization.The property of peptides to form stable complexes with metal ions is exploited to achieve metal-ion recognition by the peptide-modified PSi-based biosensor. An electrochemical study of the GlyHisGlyHis-modified PSi electrode is achieved in the presence of copper ions. The recorded cyclic voltammograms show a quasi-irreversible process corresponding to the Cu(II)/Cu(I) couple. The kinetic factors (the heterogeneous rate constant and the transfer coefficient) and the stability constant of the complex formed on the porous silicon surface are determined. These results demonstrate the potential role of peptides grafted on porous silicon in developing strategies for simple and fast detection of metal ions in solution.     

ON THE SWELLING OF SUBMERGED JETS OF DILUTE AND SEMI-DILUTE POLYMER SOLUTIONS

Profound jet swelling is shown to exist when a dilute or semi-dilute solution of PEO (POLYOX WSR 301) is ejected from a capillary tube into a stagnant fluid. The jet swells up to ten times the diameter of the capillary tube depending on the shear rate in the tube and on the density difference between the ejected and the stagnant fluid. The diameter ratio (jet/tube) grows as the 1/3 power of the shear rate, regardless of the density difference, tube diameter and polymer concentration and provided the tube is long enough for the development of the flow profile. For SEPARAN AP 45 solutions, displaying a non-Newtonian behaviour in shear, it is shown that the 1/3 power law holds between the diameter ratio and the shear stress, instead of the shear rate. The analogy between the swelling behaviour of these dilute and semi-dilute polymer solutions and the one observed in concentrated solutions and melts is discussed. The possibility of utilizing the submerged jet technique to compute the polymer solution normal stresses is considered.