A compact model of MOSFET mismatch for circuit design

This paper presents a compact model for MOS transistor mismatch. The mismatch model uses the carrier number fluctuation theory to account for the effects of local doping fluctuations along with an accurate and compact dc MOSFET model. The resulting matching model is valid for any operation condition, from weak to strong inversion, from the linear to the saturation region, and allows the assessment of mismatch from process and geometric parameters. Experimental results from a set of transistors integrated on a 0.35 /spl mu/m technology confirm the accuracy of our mismatch model under various bias conditions.     

Failure and scaling properties of a softening interface connected to an elastic block

The damage growth in a softening interface connected to an elastic block is analysed. The elastic block, assumed to be infinite, is modelled as a two-dimensional continuum and the interface is one-dimensional with a constitutive response which follows a scalar damage model. The solution technique is based on the equilibrium of the interfacial forces resulting from the deformation of the elastic block and from the interface constitutive response. The interface failure process is compared to that of a hierarchical model which was obtained analytically (Delaplace et al., 1998). The two are found to be similar, without an internal length scaling the distribution of damage at the inception of macro-cracking. Finally, scale effects on the occurrence of bifurcation and instability are considered. It is shown that bifurcation may occur prior to or after the limit point under displacement control, depending on the elastic block height or stiffness. This revised version was published online in July 2006 with corrections to the Cover Date.     

Control of nonlinear chained systems: from the Routh-Hurwitzstability criterion to time-varying exponential stabilizers

We show how any linear feedback that stabilizes the origin of a linear chain of integrators induces a simple, continuous time-varying feedback that exponentially stabilizes the origin of a nonlinear chained-form system. The design method is related to a method developed by M'Closkey and Murray (1997) to transform smooth feedback yielding slow polynomial convergence into continuous homogeneous ones that give exponential convergence     

2,7‐Carbazolenevinylene‐Based Oligomer Thin‐Film Transistors: High Mobility Through Structural Ordering

We have fabricated organic field‐effect transistors based on thin films of 2,7‐carbazole oligomeric semiconductors 1,4‐bis(vinylene‐(N‐hexyl‐2‐carbazole))phenylene (CPC), 1,4‐bis(vinylene‐(N′‐methyl‐7′‐hexyl‐2′‐carbazole))benzene (RCPCR), N‐hexyl‐2,7‐bis(vinylene‐(N‐hexyl‐2‐carbazole))carbazole (CCC), and N‐methyl‐2,7‐bis(vinylene‐(7‐hexyl‐N‐methyl‐2‐carbazole))carbazole (RCCCR). The organic semiconductors are deposited by thermal evaporation on bare and chemically modified silicon dioxide surfaces (SiO₂/Si) held at different temperatures varying from 25 to 200 °C during deposition. The resulting thin films have been characterized using UV‐vis and Fourier‐transform infrared spectroscopies, scanning electron microscopy, and X‐ray diffraction, and the observed top‐contact transistor performances have been correlated with thin‐film properties. We found that these new π‐conjugated oligomers can form highly ordered structures and reach high hole mobilities. Devices using CPC as the active semiconductor have exhibited mobilities as high as 0.3 cm² V^–1 s^–1 with on/off current ratios of up to 10⁷. These features make CPC and 2,7‐carbazolenevinylene‐based oligomers attractive candidates for device applications.     

Traduction et validation canadienne-fran?aise du Nisonger Child Behavior Rating Form.

The authors have translated the Nisonger Child Behavior Rating Form (Nisonger CBRF) into French. The resulting Grillee d'évaluation comportementale pour enfants Nisonger (GéCEN) was completed by 383 parents and 328 teachers. The congruence coefficients between the factor structure obtained from the Québec data and that obtained from the American data are also presented. Except for the congruence coefficient for the irritability scale from the GéCEN-teacher, the congruence coefficients for the parent and teacher profiles exhibit a good level of factor stability between the Nisonger CBRF, and the GéCEN. The internal consistency indicators are good to excellent for the GéCEN-parent and the GéCEN-teacher. The clinical applications of this dual diagnosis assessment tool (mental retardation and psychopathology) among children and teenagers are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Compact MMIC CPW and asymmetric CPS branch-line couplers and Wilkinson dividers using shunt and series stub loading

Circuit size may be reduced by up to 60% by embedding series and shunt uniplanar stubs inside the main uniplanar line since this reuses physical space in the longitudinal direction. This size-efficient stub loading of the main uniplanar line results in robust options for designing compact K-band 90/spl deg/ hybrid couplers and Wilkinson dividers. The approach is confirmed by experimental results that agree well with theory up to at least 30 GHz using both coplanar waveguide (CPW) and asymmetric coplanar stripline (ACPS). Furthermore, these couplers and dividers do not use lumped inductors or capacitors and, consequently, have excellent design accuracy even at millimeter-wave frequencies. Additionally, it is shown that it is possible to design an ACPS 90/spl deg/ branch-line coupler without the conventional CPW quarter wavelength transformers used to match the input and output port characteristic impedances.     

Make arc erosion and welding in the automotive area

A make arc has been investigated using a new testing apparatus. This apparatus which includes a piezo-translator, enables controlled bouncing to be studied at make under mechanical conditions similar to those encountered in automotive relays. Material transfer and welding tendency of silver, silver alloys and silver metal oxide contact materials have been studied under inductive, resistive and lamp loads at 14 V dc and 10-70 A. With all loads, anode to cathode material transfer has been observed. AgCdO, Ag and AgNi under lamp and resistive loads show the highest material transfer, as opposed to non doped and doped AgSnO₂ under inductive loads. This well known transfer is due to the anodic arc, which occurs during bounces when the gap between the contacts is shorter than ~5 μm, at the beginning and the end of the bounce. We have demonstrated that welding occurs at the beginning of the bounce, i.e. when the contacts begin to separate under arc, and not when the contacts close under arc at the end of the bounce. It was found that welding occurs mainly with Ag, AgCdO, AgZnO, AgFeRe, and AgFeO_x contact materials, and under high inrush current produced by lamp loads     

Experimental investigation of a new type of interfacial instability in a reactive coextrusion process

This paper deals with the study of new interfacial instabilities, called “grainy” defects, in coextrusion process of reactive multilayer polymers. The main objective was to better understand this phenomenon since no help can be found in the literature. The fundamental approach from a micro‐scale to a macro‐scale involves the study of relationships between polymer structure, processing, and interfacial properties. The influence of these parameters on the generation of “grainy” defects during coextrusion has been assessed in correlation with physicochemical properties. Through this work, rheological properties and the interfacial morphology between tie and barrier layers have been investigated by shear stress relaxation experiments and transmission electronic microscopy, respectively. Depending on the reactive polymers, the interfacial coupling was found to significantly alter the stress relaxation behavior by extending the relaxation time and generating an interfacial roughness. Hence, relations between the copolymer architecture, the relaxation process, and the interfacial morphology were established in correlation with the generation of grainy defects in coextrusion process. POLYM. ENG. SCI., 55:2542–2552, 2015. © 2015 Society of Plastics Engineers     

Assessing the Antimicrobial Activity of Polyisoprene Based Surfaces

There has been an intense research effort in the last decades in the field of biofouling prevention as it concerns many aspects of everyday life and causes problems to devices, the environment, and human health. Many different antifouling and antimicrobial materials have been developed to struggle against bacteria and other micro- and macro-organism attachment to different surfaces. However the “miracle solution” has still to be found. The research presented here concerns the synthesis of bio-based polymeric materials and the biological tests that showed their antifouling and, at the same time, antibacterial activity. The raw material used for the coating synthesis was natural rubber. The polyisoprene chains were fragmented to obtain oligomers, which had reactive chemical groups at their chain ends, therefore they could be modified to insert polymerizable and biocidal groups. Films were obtained by radical photopolymerization of the natural rubber derived oligomers and their structure was altered, in order to understand the mechanism of attachment inhibition and to increase the efficiency of the anti-biofouling action. The adhesion of three species of pathogenic bacteria and six strains of marine bacteria was studied. The coatings were able to inhibit bacterial attachment by contact, as it was verified that no detectable leaching of toxic molecules occurred.     

On the Issue of Incomplete and Missing Water-Quality Data in Mine Site Databases: Comparing Three Imputation Methods

Large water-quality databases are valuable for predicting mine drainage chemistry, identifying optimal measures for mitigation and remediation, and refuting/refining models and theories. However, such databases often have missing values due to periodic lack of sampling and analysis or input errors. These missing values lead to problems in machine learning and statistical analysis of water-quality data from mine sites. Using water-quality data collected from 1971 to 1994 from many locations at a copper-molybdenum-gold-silver-rhenium mine site, we compared three imputation methods to estimate missing water-quality data: iterative robust model-based imputation (IRMI), multiple imputations of incomplete multivariate data (AMELIA), and sequential imputation for missing values (IMPSEQ). These methods were evaluated based on mean absolute error, relative absolute error, and percent bias techniques. The results showed that IMPSEQ and IRMI are suitable to impute missing values in water-quality databases at mine sites, whereas AMELIA is not.