A Low-Power Integrated Bioamplifier With Active Low-Frequency Suppression

We present in this paper a low-power bioamplifier suitable for massive integration in dense multichannel recording devices. This bioamplifier achieves reduced-size compared to previous designs by means of active low-frequency suppression. An active integrator located in the feedback path of a low-noise amplifier is employed for placing a highpass cutoff frequency within the transfer function. A very long integrating time constant is achieved using a small integrated capacitor and a MOS-bipolar equivalent resistor. This configuration rejects unwanted low-frequency contents without the need for input RC networks or large feedback capacitors. Therefore, the bioamplifier high-input impedance and small size are preserved. The bioamplifier, implemented in a 0.18-mum CMOS process, has been designed for neural recording of action potentials, and optimised through a transconductance-ef-ficiency design methodology for micropower operation. Measured performance and results obtained from in vivo recordings are presented. The integrated bioamplifier provides a midband gain of 50 dB, and achieves an input-referred noise of 5.6 muVrms. It occupies less than 0.050 mm² of chip area and dissipates 8.6 muW.     

Differential diagnosis of spall vs. cracks in the gear tooth fillet region: Experimental validation

This paper presents a technique to differentially diagnose two types of localized gear tooth faults: a spall and a crack in the gear tooth fillet region. These faults could have very different prognoses, but existing diagnostic techniques only detect the presence of localized tooth faults without being able to differentiate between a spall and a crack. The effects of spalls and cracks on the behaviour of gear assemblies were studied using static and dynamic simulation models. Changes in the kinematics of a pair of meshing gears due to a gear tooth fillet crack (TFC) and a tooth flank spall were compared using a static analysis model. The difference in the variation of the transmission error (TE) caused by the two faults reveals their characteristics. The effect of a tooth crack depends on the change in stiffness of the tooth while the effect of a spall is dominantly determined by the geometry of the fault. A technique has previously been proposed to detect spalls [M. EL Badaoui, J. Antoni, F. Guillet, J. Daniere, Use of the moving cepstrum integral to detect and localize tooth spalls in gears, Mechanical System and Signal Processing, 15 (5) (2001) 873–885; M. EL Badaoui, V. Cahouet, F. Guillet, J. Daniere P. Velex, Modelling and detection of localized tooth defects in geared systems, Transaction of ASME, 123 (2001) 422–430], using the cepstrum to detect a negative echo in the signal (from entry into and exit from the spall) and successfully performed differential diagnosis on the simulated vibration signals. While the result of the experimental study showed some differences from the result of the simulation study, the differential diagnosis was successfully performed based on the technique presented in this paper. Further investigation revealed non-linear gearmesh behaviour which was causing differences in the experimental and simulation model results.     

Amino‐functionalised mesoporous silica microspheres for immobilisation of Candida antarctica lipase B – application towards greener production of 2,5‐furandicarboxylic acid

In the present study, amino‐functionalised mesoporous silica microspheres were utilised as support for the covalent immobilisation of Candida antarctica lipase B (CaLB) for the subsequent production of 2,5‐furandicarboxylic acid (FDCA) from 2,5‐diformylfuran (DFF). Under the optimised operating conditions of pH 6.5, particle/enzyme ratio of 1.25:1.0 and glutaraldehyde concentration of 4 mM, a maximum CaLB immobilisation yield of 82.4% on silica microspheres was obtained in 12.25 h. The immobilised CaLB was used for the synthesis of alkyl esters, which were utilised along with hydrogen peroxide for FDCA synthesis. The biocatalytic conversion of 30 mM DFF dictated a 77–79% FDCA in 48 h at 30°C; where the turnover number and turnover frequency of immobilised CaLB were 6220.73 mol mol⁻¹ and 129.59 h⁻¹, respectively, for ethyl acetate, against 6297.65 mol mol⁻¹ and 131.2 h⁻¹, respectively, for ethyl butyrate. Upon examining the operational stability, the immobilised CaLB exhibited high stability till five cycles of FDCA production.Inspec keywords: mesoporous materials, organic compounds, biotechnology, silicon compounds, renewable materials, catalysis, catalysts, enzymes, thermal stability, biofuelOther keywords: FDCA production, amino‐functionalised mesoporous silica microspheres, greener production, 2,5‐furandicarboxylic acid, covalent immobilisation, 2,5‐diformylfuran, CaLB immobilisation, Candida antarctica lipase B immobilisation, ethyl butyrate, time 48.0 hour, temperature 30.0 degC, time 12.25 hour     

A computational method for calculating heat transfer and airflow through a dual-airflow window

An airflow window has great potential for conserving energy and improving indoor air quality in residential buildings. Existing airflow windows use a single airflow path, and their energy performance can be studied using several computational models. A dual-airflow window with triple glazing can conserve more energy than a single-airflow window, because the former works like a cross-counterflow heat exchanger. However, no suitable computer programs can be used to evaluate the energy performance of the dual-airflow window. This paper proposes a four-step computational method that uses both computational fluid dynamics (CFD) and coded radiation calculations to determine airflow and heat transfer through the window. Experimental tests on a full-scale dual-airflow window system were used to obtain various indoor and outdoor air and window surface temperatures for validating the computer method. The agreement between the computed and measured temperatures is very good.     

Low salt petroleum produced water reuse: a farming alternative outside the food chain.

Oil and gas production gives rise to water production depending on the state of maturation of the Field. This means large volumes of water available. Today, this water is partly re-injected into the reservoir. Totalfinaelf's sustainable contribution to preserve water resources is to propose an alternative utilization: the reuse of produced waters from petroleum activities, outside the food chain. The aim of the first part of this study is to demonstrate the feasibility of utilizing low-salt water (<20 g/l) cleaned of hydrocarbons, for agricultural or forest irrigation. Rudimentary technologies such as artificial wetlands were tested to remove hydrocarbon substances and preliminary tests were performed with cotton (Gossypium hirsutum) and hemp (Cannabis sativa). Among the species tested in real conditions (greenhouse), hemp was affected by saline water whereas the results obtained for cotton were representative of the average worldwide production. These results validate the reuse of low-salt produced water in climatic conditions with expected temperatures of up to 37 degrees C in summer and 25 degrees C in winter. Following these results, field pilots are planned. Further research is planned to focus, taking into account local needs and environmental and production constraints.     

160-Gb/s optical networking: a prospective techno-economical analysis

This paper reports on a network dimensioning analysis of N /spl times/ 160-Gb/s wavelength-division-multiplexed (WDM) networks based on the optical time-division-multiplexing (OTDM) technique. The need for different transmission and networking functions based on innovative circuit-switched scenarios for optical core networks is quantified, and the economical interest of such high-wavelength channel bit rates in the chosen scenarios is evaluated.     

Why do we SLIP to the basic level? Computational constraints and their implementation.

The authors introduce a new measure of basic-level performance (strategy length and internal practicability; SLIP). SLIP implements 2 computational constraints on the organization of categories in a taxonomy: the minimum number of feature tests required to place the input in a category (strategy length) and the ease with which these tests are performed (internal practicability). The predictive power of SLIP is compared with that of 4 other basic-level measures: context model, category feature possession, category utility, and compression measure, drawing data from other empirical work, and 3 new experiments testing the validity of the computational constraints of SLIP using computer-synthesized 3-dimensional artificial objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Natural cement and monumental restoration

Natural cement, called “Roman” cement, was invented at the end of the 19th century and played an important role in the development of civil engineering works until the 1860s. More surprisingly, it was also used to restore historic buildings, such as gothic cathedrals. This paper deals with the mineralogy and the durability of natural cement in the particular case of the Bourges Cathedral in France. This study illustrates the interest of this material particularly adapted in stone repair or substitution. Contrary to traditional mortars, the present samples are made of neat cement paste, revealed by the absence of mineral additions as quartz or carbonate sand. Several combined techniques (SEM-EDS, TGA, XRD) were carried out to determine the composition of the hydraulic binder rich in calcium aluminate hydrates. The raw marl at the origin of the cement production contains oxidized pyrites which consist in a potential source of sulphate pollution of the surrounding limestone. The exposition of the cement in urban environment leads to some weathering features as atmospheric sulfation. Finally a petrophysical approach, based on water porosity, capillary sorption and compressive strength, has been performed to demonstrate the durability and the compatibility of natural cement applied as an historical building restoration mortar.