6?10 GHz ultra-wideband CMOS LNA

A two-stage matched ultra-wideband CMOS low noise amplifier (LNA) is presented. The LNA is designed to achieve a low noise figure with high voltage gain. The LNA fabricated in a 0.13 mum CMOS process shows a 3.9 dB average noise figure with a 27 dB voltage gain in the 6-10 GHz frequency band with a power consumption of 14 mW.     

Globally stabilizing control of fed-batch processes with Haldane kinetics using growth rate estimation feedback

The regulation of the biomass specific growth rate is an important goal in many biotechnological applications. To achieve this goal in fed-batch processes, several control strategies have been developed employing a closed loop version of the exponential feeding law, an estimation of the controlled variable and some error feedback term. In the case of non-monotonic kinetics, the specified growth rate can be achieved at two different substrate concentration values. Because of the inherent unstable properties of the system in the decreasing portion of the kinetics function, stabilization becomes a crucial problem in this high-substrate operating region. In this context, the dynamic behavior of fed-batch processes with Haldane kinetics is further investigated. In particular, some conditions for global stability and performance improvement are derived. Then, a stabilizing control law based on a partial state feedback with gain dependent on the output error feedback and gain saturation is proposed. Although particular emphasis is put on the critical case of high-substrate operation, low-substrate regulation is also treated.     

MPEG-4: a multimedia standard for the third millennium. 2

MPEG-4 defines a multimedia system for interoperable communication of complex scenes containing audio, video, synthetic audio, and graphics material. In part 1 of this two-part article (Battista et al., 1999) we provided a comprehensive overview of the technical elements. In part 2 we describe an application scenario based on digital satellite television broadcasting, discuss the standard's envisaged evolution, and compare it to other activities in forums addressing multimedia specifications     

Dynamical variable structure controller for power regulation of wind energy conversion systems

The paper addresses the problem of output power regulation of fixed-pitch variable-speed wind energy conversion systems. Operation is constrained by practical reasons to the low-speed side of the turbine power-speed curve. Unfortunately, this region is characterized by a nonminimum phase dynamics which is an obstacle to perform the regulation task. A dynamical variable structure controller is developed that accomplishes the control objective despite this limitation. The proposed control strategy presents attractive features such as robustness to parametric uncertainties of the turbine and generator as well as to electric grid disturbances.     

Second-order sliding mode observer for biomass concentration and growth rate estimation in batch photo-bioreactors

In this work the problem of estimating some variables of interest for monitoring and control of photo-fermentation processes is addressed. The focus is on a batch cultivation of Rhodobacter capsulatus where biohydrogen production rate is represented by a Luedeking–Piret expression. The use of second-order sliding mode algorithms to estimate biomass concentration and bacterial specific growth rate is explored. It is concluded that the proposed observer does not require a kinetic model, thus eliminating a source of uncertainty. Also, it is shown that the error dynamics converges exponentially with short time constant determined by process parameters. Numerical simulations corroborate the convergence properties of the algorithm in the nominal case, as well as its robustness against parametric uncertainty and its performance under noisy measurement.     

Hydrogen production from idle generation capacity of wind turbines

This paper is concerned with the hydrogen production from wind energy. It is motivated by the new regulations for wind farms that compel them to operate normally with idle generation capacity. The idea is to use the excess wind power to produce hydrogen. The operation of a proposed system configuration, which essentially consists in incorporating an electrolyzer between the electronic converters of a conventional wind turbine, is analyzed. In particular, the control requirements to simultaneously achieve the grid and electrolyzer specifications are investigated. In this context, a control strategy for the different operating modes of the system is developed.     

Optimal gain-scheduled control of fixed-speed active stall wind turbines

For a smooth integration of large wind farms into the utility grids, the individual wind turbines must be able to achieve various power control objectives. In this context, the authors focus their attention on the control of fixed-speed active stall wind turbines. This sort of turbine includes a pitch servomechanism to induce stall on the blades, thereby having control on the output power. The authors develop a methodology to design optimal gain-scheduled pitch controllers valid for the whole operating region of the wind turbine. The proposed solution uses concepts of linear parameter-varying system theory. In addition to providing a formal framework for the control design, this theory guarantees stability and performance. Further, because of the similarities with Hαcontrol, the tools developed for the controller design are very familiar to the control community. The main features of the proposed controller are assessed by means of numerical simulations obtained for realistic wind speed profiles and power production demands.     

Design and implementation of UWB CMOS LC filters LNA for carrier less impulse radio receivers

The design and the implementation of Ultra-wide-band (UWB) CMOS LC filter LNA for Ultra Wide Band carrier less Impulse Radio receivers is presented. Architectures for both single ended and differential ended LNA are proposed for small fractional bandwidths such as the ECC frequency band and for large fractional bandwidths such as FCC frequency band. Simple guidelines to achieve large voltage gain and low noise figure are given. The implementation in standard CMOS technologies in the context of integrated receivers is discussed and simple layout rules allowing reliable designs are proposed. Several LNA prototypes for different fractional bandwidths have been fabricated in a 0.13 μm CMOS technology. Measurement results agree well with the simulations.     

Derivatives of apomorphine and of other N-substituted norapomorphines

Derivatives of apomorphine and of N-n-propylnorapomorphine were prepared to obtain modified pharmacological activity and enhanced chemical stability. Mouse profile and dog emesis screens were performed, and the activity of various N-substituted derivatives and their esters was evaluated and compared to the parent compounds. The N-n-propyl diacetate derivative and N-methyl and N-n-propyl ascorbate salts were remarkably stable to air: apomorphine etherate was no more stable than the free base. The dimers, the major products formed during the acid-catalyzed rearrangement of morphines to apomorphines, were all potent emetics. Additionally, two showed a significant antagonism to morphine in mice and dogs.