Diffusion field in coal stratum

IPKON, Academy of Sciences of the USSR, Moscow. Translated form Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 109–111, July–August 1991.     

On the using of modal curves for radar waveforms classification

Recent advances in nonparametric functional data analysis allow to define the notion of mode for a sample of curves. A kernel-type estimator is proposed for estimating this modal curve. In addition, other centrality curves can be easily extended to the functional case, namely mean and median curves. A nonparametric unsupervised classification method which is also a cluster analysis is investigated. This is based on the comparison between the modal curve with another centrality curve for measuring some heterogeneity index. The main point is to show the good practical behaviour of this hierarchical classification on a sample of radar waveforms registered from the satellite Topex/Poseidon upon the Amazonian basin. In addition, a few theoretical advances are provided.     

Silicon technologies for applications up to millimetre-waves: Some design guidelines

This paper presents some guidelines for the design of silicon circuits, which are able to achieve state of the art performances in the microwave frequency range despite their integration with a standard technology. Firstly, we point out the benefits which may be expected from the large number of available metallic layers, and which make possible the implementation of highly integrated and low loss interconnects and passives. Next, we emphasize the advantages of microwave differential structures: without any increase of the circuit complexity, a very well balanced behaviour can be reached leading to a strong attenuation of common mode parasitic signals. Finally, the interest and the feasibility of mixed-mode circuits (analog with digital) are demonstrated through dedicated designs for microwave frequency synthesis. Christophe Viallon received the M.S. degree and the Ph.D. degree in electrical engineering from Paul Sabatier University, Toulouse, France in 1999 and 2003 respectively. From 2000 to 2004 he was with the Laboratory of Analysis and Architecture of Systems (LAAS), Toulouse, France, where he was conducting research on the optimization of differential circuit topologies for millimeter-wave applications using SiGe BiCMOS technologies. Since 2005, he is an associate professor at Paul Sabatier University, and his researches at the LAAS laboratory are mainly focused on nonlinear microwave integrated circuit design and above-IC passive elements development. éric Tournier was born in Saint-Jean d’Angely, France, in 1970. He received the Engineer degree and the Ph.D. degree both from the Institut National des Sciences Appliqu, Toulouse, France, in 1993 and 1998 respectively. Since September 1998, he has been an associate professor of electrical engineering at the university of Toulouse, and a researcher at the Laboratoire d’Analyse et d’Architecture des Systèmes (LAAS). He has worked on low frequency analog, digital and smart-power integrated circuits design, and is now involved in microwave circuits design methodologies on silicon technologies for telecommunication ICs. He currently works on digital design applied to high frequency synthesis (frequency dividers, phase/frequency detectors and direct digital synthesis (DDS)), and analog design using BAW devices. Thierry Parra was born in August 1964. He received the Ph.D. degree in electronics engineering and the accreditation to supervise research in 1991 and 1999, respectively, both from the Paul Sabatier University (UPS), Toulouse, France. He joined the LAAS-CNRS in 1991, and since 2002 he is Professor of electrical engineering. His research interests are currently on microwave components and new materials characterisation and modelling, and on optimisation and design of microwave integrated circuits, up to the millimeter wave frequency range.     

High-frequency capacitance-voltage characteristic of GaAs-based, thin-film structures

An analytical calculation of the high-frequency capacitance-voltage characteristic of a GaAs thin-film structure is carried out. It is shown that the peculiarities of this characteristic, namely an abrupt drop followed by a falloff to zero, are due to the merging of the depletion regions of the Schottky barrier and the film-substrate junction and to a lag in the recharging of deep centers in the substrate. Fiz. Tekh. Poluprovodn. 31, 96–99 (January 1997)     

Material and electrical characteristics of iron doped Pt-lnAIAs schottky diodes grown by LP-MOCVD

InAlAs lattice-matched to InP is of great importance as a large bandgap material for various InP-based heterostructures device applications. However, growth of good quality InAlAs using metalorganic chemical vapor deposition (MOCVD) is relatively difficult due to the reactive nature of its aluminum sources. In this paper, we present the use of iron as a possible dopant to improve the electrical properties of MOCVD grown InAlAs. Time resolved photoreflectance was used to confirm the increase in trap levels with increased iron doping. The impact of iron doping on the electrical properties of devices was investigated using Pt-Schottky diodes fabricated on undoped and iron doped InAlAs materials. Low frequency noise measurements were also carried out to investigate the impact of iron incorporation on the noise characteristics of the devices. Although noise levels showed marginal difference between undoped and iron doped materials, iron doped InAlAs showed a Lorentzian component in the noise spectra which is not found in undoped materials. An activation energy of ∼0.77 eV was evaluated for traps introduced by iron incorporation using temperature dependent low frequency noise measurements.     

Effects of parturition and maternal experience on noradrenaline and acetylcholine release in the olfactory bulb of sheep.

Acetylcholine (ACh) and noradrenaline (NA) release in the olfactory bulb (OB) of ewes was monitored using microdialysis. Both ACh and NA release increased at parturition in multiparous but not in primiparous ewes. However, vaginocervical stimulation performed 6 hrs postpartum induced an increase of ACh and NA release in both primiparous and multiparous ewes, indicating that a maturation process had occurred. Finally, pharmacological challenges to the ACh and NA inputs revealed differential responsiveness between nulliparous and multiparous nongestant ewes. These results suggest that the 1st parturition induces changes in neural circuitry involving ACh and NA inputs to the OB. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessing the biomass dynamics of Andean bofedal and totora high-protein wetland grasses from NOAA/AVHRR

Biomass measurements of totora and bofedal Andean wetland grasses in the Bolivian Northern Altiplano were correlated over a growing season to vegetation indices derived from 1-km visible and near-infrared bands of the advanced very high resolution radiometer (AVHRR) instrument flown on the NOAA-14 polar-orbiting meteorological satellite. This article discusses the potential and limits of these indices for the assessment of the spatial and temporal variation of biomass and of the fraction of the photosynthetic active radiation absorbed by these herbaceous native forages growing in water-saturated environments. Bidirectional reflectance distribution function (BRDF) normalization was also investigated based on simple kernel-driven models. BRDF normalized difference vegetation index (NDVI) performed the best for both totorales and bofedales vegetation associations, followed by the uncorrected maximum-value composite NDVI. BRDF normalized NDVI was shown to be sensitive to the green leaf or photosynthetically active biomass.Estimation of biomass production after Kumar and Monteith (1982) was used to determine the efficiency of solar energy conversion into biomass (ε_b) for the main phenological periods, corresponding to the rainy and dry seasons. Two approaches were investigated for the biomass production estimation: the first one is based on monthly field biomass measurements; the second one is based on estimates from the regression computed previously using Roujean's BRDF normalized NDVI. The values found for these efficiencies for the rainy season agree with those of the literature for grasslands of temperate regions. For the dry season, more accurate information on totora and bofedal senescence and on animal consumption is required to get a reasonable efficiency value. This is not surprising, as other workers have reported biomass estimation with remotely sensed data to be most relevant to the growing season.     

Optimal bandwidth selection for multivariate kernel deconvolution density estimation

Assume we have i.i.d. replications from the mismeasured random vector Y=X+ε, where X and ε are mutually independent. We consider a data-driven bandwidth, based on a cross-validation ideas, for multivariate kernel deconvolution estimator of the density of X. The proposed data-driven bandwidth selection method is shown to be asymptotically optimal. As a by-product of the proof of this result, we show that the average squared error, the integrated squared error, and the mean integrated squared error are asymptotically equivalent error measures.      

The declining scientific impact of theses: Implications for electronic thesis and dissertation repositories and graduate studies

Although the writing of a thesis is a very important step for scientists undertaking a career in research, little information exists on the impact of theses as a source of scientific information. Knowing the impact of theses is relevant not only for students undertaking graduate studies, but also for the building of repositories of electronic theses and dissertations (ETD) and the substantial investment this involves. This paper shows that the impact of theses as information sources has been generally declining over the last century, apart from during the period of the ‘golden years’ of research, 1945 to 1975. There is no evidence of ETDs having a positive impact; on the contrary, since their introduction the impact of theses has actually declined more rapidly. This raises questions about the justification for ETDs and the appropriateness of writing monograph style theses as opposed to publication of a series of peer-reviewed papers as the requirement for fulfilment of graduate studies.     

Haptic feedback in mixed-reality environment

The training process in industries is assisted with computer solutions to reduce costs. Normally, computer systems created to simulate assembly or machine manipulation are implemented with traditional Human-Computer interfaces (keyboard, mouse, etc). But, this usually leads to systems that are far from the real procedures, and thus not efficient in term of training. Two techniques could improve this procedure: mixed-reality and haptic feedback. We propose in this paper to investigate the integration of both of them inside a single framework. We present the hardware used to design our training system. A feasibility study allows one to establish testing protocol. The results of these tests convince us that such system should not try to simulate realistically the interaction between real and virtual objects as if it was only real objects.