High resolution processing techniques for ultrasound doppler velocimetry in the presence of colored noise. Part I: Nonstationary methods

Real-time flow velocity measurement is a practical issue in industrial and biomedical applications. Because their good frequency resolution, parametric methods such as autoregressive (AR) modeling and time-frequency distributions (TFD) are generally preferred to Fourier analysis. However, these methods become highly inaccurate in the presence of colored noise. We review here the principal parametric and nonparametric techniques and show their limitations in the estimation of Doppler frequency in the presence of strong colored noise. Different solutions to overcome these limitations are then proposed and compared using synthetic Doppler signals with colored noise.     

High resolution processing techniques for ultrasound doppler velocimetry in the presence of colored noise. Part II: Multiplephase pipe-flow velocity measurement

For pt.I see ibid., vol.50, no.3, p.267-78 (2003). This paper presents an application of continuous wave ultrasound Doppler velocity measurements to two-phase flow in pipes. In many petroleum wells, the multiphase flow is separated into two phases: the first is a liquid phase and the second is a gas phase with small scatterers. The problem of multiphase velocity profile measurements has not been satisfactorily solved by classical approaches due to the multiphase nature of the fluid and the presence of colored noise, which introduces a significant bias in classical frequency estimators. We propose the use of resolution frequency techniques to overcome the classical limitations. Direct estimation of Doppler frequency then obtained using either time frequency maximum frequency or arguments of poles of the parametric model that identifies the Doppler part of the signal is discussed. The tests made with synthetic Doppler signals and two-phase flow have demonstrated the excellent performance of the high resolution techniques based on reassignment and parametric techniques.     

Regular Languages Defined by Generalized First-Order Formulas with a Bounded Number of Bound Variables

Abstract. We consider generalized first-order sentences over < using both ordinary and modular quantifiers. It is known that the languages definable by such sentences are exactly the regular languages whose syntactic monoids contain only solvable groups. We show that any sentence in this logic is equivalent to one using three variables only, and we prove that the languages expressible with two variables are those whose syntactic monoids belong to a particular pseudovariety of finite monoids, namely the wreath product of the pseudovariety DA (which corresponds to the languages definable by ordinary first-order two-variable sentences) with the pseudovariety of finite solvable groups. This generalizes earlier work of Thérien and Wilke on the expressive power of two-variable formulas in which only ordinary quantifiers are present. If all modular quantifiers in the sentence are of the same prime modulus, this provides an algorithm to decide if a regular language has such a two-variable definition.     

Dirty RF: A New Paradigm

The implementation challenge for new low-cost low-power wireless modem transceivers has continuously been growing with increased modem performance, bandwidth, and carrier frequency. Up to now we have been designing transceivers in a way that we are able to keep the analog (RF) problem domain widely separated from the digital signal processing design. However, with today’s deep sub-micron technology, analog impairments – “dirt effects” – are reaching a new problem level which requires a paradigm shift in the design of transceivers. Examples of these impairments are phase noise, non-linearities, I/Q imbalance, ADC impairments, etc. In the world of “Dirty RF” we assume to design digital signal processing such that we can cope with a new level of impairments, allowing lee-way in the requirements set on future RF sub-systems. This paper gives an overview of the topic and presents analytical evaluations of the performance losses due to RF impairments as well as algorithms that allow to live with imperfect RF by compensating the resulting error effects using digital baseband processing.     

High pass filter with above IC integrated SrTiO3 high K MIM capacitors

This paper describes realization and characterization of SrTiO₃ (STO) high K MIM capacitors above BiCMOS integrated circuit (IC). These capacitances are connected to IC and are used as coupling capacitors in order to realize a high pass filter. Surface capacitance achieved is 10 nF/mm² with capacitance value of 1.2 nF. The process for STO MIM fabrication does not exceed 400 °C, which is compatible with interconnections. Typical K and dielectric losses values obtained are, respectively 110% and 2%. Yield obtained reaches 83% for capacitors. A functional high pass filter using these STO capacitors was realized in this study. It exhibits a cut-off frequency at 6.5 kHz and a constant gain at higher frequencies of −1.3 dB.     

用于敞开式变电站的特高压开关设备

作为1 100 kV的UHV(特高压)输电,面临技术--生态环境的巨大挑战.变电站的UHV开关装置模块,需要的是可靠、成本/效益比好、环境友好、可维护的方案.对于这些所需的参数以及技术规范的验证,采用AIS(空气隔离变电所)技术能完全满足这些需要.介绍由瓷柱式断路器、隔离开关和NCIT(非传统互感器)所组成的UHV模块.这些装置是根据模块原理预先设计好的,其中的设备间的连接肯定允许快速安装.在变电站设备控制和检测方面,模块是预制标准化.加拿大和德国的试验站对断路器、隔离开关等独立的开关元件,在1 100 kV上做BIL、SIL和工频等绝缘试验,性能表现非常优越.因为对于特高压电压等级,IEC标准至今尚未规定,所以将根据外推法和现场数据作合理解释.瓷柱式断路器采用了最新复合绝缘体技术,在安全方面有所改进.AIS方案其他的关键技术,例如环境保护和成本,在可比的功能间,根据市场估计价值,与GIS解决方法作了比较.     

Anisotropic nanowire growth via a self-confined amorphous template process: A reconsideration on the role of amorphous calcium carbonate

Calcium carbonate crystals with various morphologies have been found in a variety of biospecimens and artificially synthesized structures. Usually, the diversity in morphology can be attributed to different types of interactions between the specific crystal faces and the environment or the templates used for the growth of CaCO₃ crystals. On the other hand, isotropic amorphous calcium carbonate (ACC) has been recognized as the precursor of other crystalline calcium carbonate forms for both in vivo and in vitro systems. However, here we propose a self-confined amorphous template process leading to the anisotropic growth of single-crystalline calcite nanowires. Initiated by the assembly of precipitated nanoparticles, the calcite nanowires grew via the continuous precipitation of partly crystallized ACC nanodroplets onto their tips. Then, the crystalline domains in the tip, which were generated from the partly crystallized nanodroplets, coalesced in the interior of the nanowire to form a single-crystalline core. The ACC domains were left outside and spontaneously formed a protective shell to retard the precipitation of CaCO₃ onto the side surface of the nanowire and thus guided the highly anisotropic growth of nanowires as a template.

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A METHODOLOGY FOR PROVISION OF SUSTAINABLE INFORMATION SYSTEMS SECURITY

Information represents one of the most important factors in the success of any enterprise today. Moreover, confidential information is becoming increasingly integrated into complex info-innovation solutions and is accordingly exposed to novel means of manipulation and theft. The legal requirements concerning information security (IS) policies in organizations are mainly based on reactive approaches that follow the standards applied in this area and are regularly updated every few years. However, a complementary approach that takes into account a fast-changing information/innovation security threats landscape and that is of proactive nature is required. Such an approach is presented in this article by linking the information security field with the field of innovation management.     

Quad‐Mesh Generation and Processing: A Survey

Triangle meshes have been nearly ubiquitous in computer graphics, and a large body of data structures and geometry processing algorithms based on them has been developed in the literature. At the same time, quadrilateral meshes, especially semi‐regular ones, have advantages for many applications, and significant progress was made in quadrilateral mesh generation and processing during the last several years. In this survey we discuss the advantages and problems of techniques operating on quadrilateral meshes, including surface analysis and mesh quality, simplification, adaptive refinement, alignment with features, parametrisation and remeshing.     

The 2008 Anti‐French Demonstrations in China: Learning from a Social Media Crisis

In this article, we propose to revisit the China of April 2008 and ponder on one major event that happened that year: the boycott of the Carrefour stores, which resulted in an unprecedented display of demonstrations and protests. After having proposed an original theoretical framework (the information cascade), we move on to carry out a detailed reading of this case in order to learn from it and have a better understanding of current crises.