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Flexibility in power systems with high penetration of wind power is the most important factor required for maintaining generation capacity and load balance. Generating reserves play a key role in this new scenario. These must be available not only in terms of quantity, but particularly in their ability to provide a suitable response rate compatible with variations in wind generation, as well as with the phenomenon of wind ramps. The generating units responsible for the AGC may not be able to compensate this variation in generating power. Taking into account, reserves must be redispatched to keep the power balance. However, since reserves have different costs and response ramps, our problem is to find out which reserves have to be redispatched at minimum cost. This paper addresses the question of the optimal dispatch of reserves against wind power ramp events by taking account of operational constraints including interruptible load contracts.

Nowadays the metal ions detection and classification in-site and in real time in river and like environment are very important task for environmental control. In this sense, the present work proposed a portable multispectral spectrometer based in the multispectral photodetector eliminating in this way the complex and expensive conventional monochromator system. The acquisition, control and processing of signals are performed based on FPGA technology, which was developed based on virtual instrumentation software (NI LabView ®), manufactured by National Instruments, NI model myRIO-1900. This portable spectrometer showed to have the same performance than to bench spectrophotometer when these are applied to metal ions detection and classification by using the PAN molecules as active indicator. The metal ions detection and classification with bench spectrometer and portable spectrometer showed to be efficient when it was used three-dimensional chromaticity diagrams. These results pointed out that the proposed portable spectrometer will be used successfully for in-situ and real time metal ions monitoring in river and like environment.

Nanowire networks are promising memristive architectures for neuromorphic applications due to their connectivity and neurosynaptic-like behaviors. Here, we demonstrate a self-similar scaling of the conductance of networks and the junctions that comprise them. A particular class of junctions naturally leads to the emergence of conductance plateaus and a “winner-takes-all” conducting path which corresponds to the lowest-energy connectivity path. These results point to the possibility of independently addressing memory or conductance states in complex systems and is expected to have important implications for nanoelectronics and neuromorphic devices.

The real time monitoring of biological microorganism growth dynamics without enter any interference is a challenging problems of nowadays. The present work report a portable multispectral system for monitoring the bacterial microorganism growth dynamics. The portable multispectral system proposed in this work is based in the optoelectronic integrated photodetector and the acquisition, control and processing of the signals based on FPGA technology, with hardware manufactured by National Instruments, NI model myRIO-1900. The results obtained with this system showed to have the same performance to the commercial biophotometer bench system.

The uncertainty associated with the increasingly wind power penetration in power systems must be considered when performing the traditional day-ahead scheduling of conventional thermal units. This uncertainty can be represented through a set of representative wind power scenarios that take into account the time-dependency between forecasting errors. To create robust Unit Commitment (UC) schedules, it is widely seen that all possible wind power scenarios must be used. However, using all realizations of wind power might be a poor approach and important savings in computational effort can be achieved if only the most representative subset is used. In this paper, the new hybrid metaheuristic DEEPSO and clustering techniques are used in the traditional stochastic formulation of the UC problem to investigate the robustness of the UC schedules with increasing number of wind power scenarios. For this purpose, expected values for operational costs, wind spill, and load curtailment for the UC solutions are compared for a didactic 10 generator test system. The obtained results shown that it is possible to reduce the computation burden of the stochastic UC by using a small set of representative wind power scenarios previously selected from a high number of scenarios covering the entire probability distribution function of the forecasting uncertainty.

Within a research programme dealing with the development of a 5.8 GHz link to be used as redundancy for a 26 GHz terrestrial point-to-point microwave link in the equatorial region, two problems are discussed in this paper. a) Drop size distribution (DSD) and the associated specific rain attenuation and b) Frequency scaling of rain attenuation statistics. Measurements were carried out in a 1.3 km long radio link located in the Skudai campus of Universiti Teknologi Malaysia (UTM). Simultaneous rainfall rate measurements were carried out in the same site with a Casella tiping bucket size of 0.5 mm rain gauge along with one minute interval. Both measurements cover the period from June 2011 to May 2012. The specific attenuation due to rain As(dB/km) is obtained from the rainfal rate R(mm/h) using the power relationship, As = kRα where k and α are functions of frequency, rain drop size distribution (DSD), temperature e polarization of the radio wave. The most common DSD model used in temperate climate is the Marshall and Palmer negative exponential function, while the log-normal distribution applies to tropical and equatorial climates. In this paper the specific attenuation has been determined directly from the collected rain attenuation. Since the path length of the experimental link is 1.3 km, the distribution of rainfall has been assumed to be uniform along the propagation path. The nonlinear relationship between specific attenuation and the rainfall intensity given in the above equation was transformed into a linear form based on a logarithmic transformation. Then a linear regression model was fitted to the measured specific attenuation and the measured rainfall rate. Based on one year of rain attenuation measurements at both frequencies, the following values of k and α were estimated, f = 5.8 GHz k = 0.138 ; α = 0.63 f = 26 GHz k = 0.389 ; α = 0.89 On the other hand, scaling of rain attenuation statistics in frequency is a useful technique if attenuation data are available at the desired locality. Many scaling models have been developed from various propagation experiments. In this paper the Rain Attenuation Statistics (RAS) is modeled according to a simple power law model given by, RAS=(F 2 /F 1 )N where f 1 is the lower frequency and f 2 the higher one. Three pair of frequencies, 5.8 GHz, 15 GHz and 26 GHz have been analysed and compared. The rain attenuation data for 5.8 GHz and 26 GHz were taken from the same link used before for the specific attenuation study, while the 15 GHz data has used previous rain attenuation information from another radio link located also in UTM. This intermediate frequency has been also used as a check for the results derived from 5.8 and 26 GHz. In summary, the analysis of the rain attenuation data has indicated the value of n = 1.57 for the power law model to be used in the frequency range from 5 to 26 GHz. In the final paper the results presented here will be compared to data from several other tropical and equatorial countries, such as Brazil, India, Nigeria, Singapore and South Africa.

Wireless Sensor Networks (WSNs) can be used to monitor large agricultural areas, as the Sao Francisco Valley region in the northeast of Brazil. The main economic activity is grape growing for export which demands high quality production in order to attend the market requirements. This work presents an experimental study of path loss in grape plantations located in this region performed based on a measurement campaign. The research will aid the deployment of WSNs in Sao Francisco Valley region.

Photoluminescence quenching-based sensors for oxygen detection are generally made with organic dyes molecules that act as active molecules. These molecules are normally immobilized into polymeric host substrate that doesn't have any compatibility with silicon technology. In this work we report a photoluminescence (PL) quenching based oxygen sensor using oxidized porous silicon layer as a host matrix for platinum-octaethylporphyrin (PtOEP) dye molecules. The device in this substrate is high sensitivity because its high surface area and it may have high compatibility with silicon technology since porous silicon is obtained on silicon substrate. The sensitivity to O2 detection of this sensor was 13 times higher than to conventional devices based on polystyrene layer and its response time was 3 times slower than polymeric based devices. In the present work, the detection mechanism and the response time of these sensors are discussed.

The present work aims the standardization of 68Ga, a positron emitter of short half-life used in PET (Positron Emission Tomography). The 68Ga standardization was performed in a triple 4πβ-γ coincidence system that consists of a thin window gas-flow proportional counter (PC) in 4π geometry coupled to a NaI(TI) scintillator and a HPGe crystal, for gamma-ray detection. The data acquisition was carried out by means of a Software Coincidence System (SCS) developed at the Nuclear Metrology Laboratory (Laboratorio de Metrologia Nuclear - LMN) at the IPEN-CNEN/SP. The final results were obtained from a multiple curve fitting applying a covariance matrix methodology combining experimental results with those determined by the Monte Carlo simulation.

Nanowire networks (NWNs) are promising candidates for a range of material and device applications. Although much is known about the percolation behaviour of nanowire systems especially in polymer composites, the inherent connectivity in high density NWNs is not at all understood. Such networks are comprised of wires that are well connected but individual wires are frequently separated by surface passivation layers that control conduction. We begin by visualising the connectivity in NWNs and show that the voltage, spatial and thickness dependences can be understood in terms of a distribution of junction properties. We introduce a universal scaling relationship that is a fundamental property of NWNs and show it is consistent with the presence of locally connected regions or pockets within the network that ultimately lead to conduction. We demonstrate that network connectivity evolves in response to an applied electric field to create materials whose conductivity can be arbitrarily controlled. This intrinsic property of NWNs can be further modulated by the changing the wire coating or surface passivation to create families of evolutionary materials and devices that exhibit novel behaviours, i.e. their properties are non-static but rather evolve and adapt in response to external stimuli.

This paper deals with the problem of diffraction by terrain irregularities. It is well-known that this problem is quite complex, the general solution requiring an integral equation normally solved by numerical methods. To avoid the difficulties associated to this solution, simplified methods are available for the evaluation of radio wave attenuation in practical cases. However, the accuracy of these methods depends on restrictions imposed by frequency, link parameters (path distance and antenna heights) and terrain profile. Propagation mechanisms such as ground wave over a smooth spherical earth and multiple diffraction by isolated obstacles are examples where the accuracy is closely related to specific topographical features. In this paper emphasis is given to the work that is being carried out in the Study Group 3 of ITU-R (Radiocommunication Sector of the International Telecommunication Union). In the Recommendation ITU-R P.526–10 there are consolidated algorithms to solve the above limiting cases. Nevertheless, an important question remains, i.e., how to handle a situation where the variations of the relief are within the limits between smooth earth and isolated obstacles? Numerical results derived from the solution currently adopted by Recommendation 526–10 to this case do not fit well when compared to experimental data. In this context, the present paper discusses some fundamental points to be taken into account in the development of a possible solution to this problem. The analysis of interaction between the terrain and the propagating wave is based on the concept of penumbra region derived from a mathematical model consisting of a smooth spherical earth surmounted with a knife-edge obstacle. A preliminary conclusion indicates that an empirical hybrid model which considers the two limiting cases referred to in the above comments seems to be the best compromise to solve the problem.

This paper deals with an experimental study carried out in a long distance VHF tropospheric path located in the Brazilian Amazon region. Measurements of the received power in this path were registered for 170 hours and clearly indicate a diurnal variation characterized by the existence of two propagation mechanisms. Scatter propagation during the day and diffraction propagation in night hours. This information, together with the knowledge of the median values of the earth k-factor derived from these measurements are important input data for planning VHF and possibly UHF radio systems in low latitude areas.

In this paper the application of Monte Carlo simulation for standardizing 111In in a 4π(PC)-NaI(Tl) coincidence system is presented. The Monte Carlo simulation is applied using ESQUEMA code, which was developed by the Nuclear Metrology Laboratory (LMN) in IPEN, Sao Paulo, Brazil. The experimental results obtained by means a linear fitting were compared with those determined by the Monte Carlo prediction and they are in good agreement within the uncertainty.

The procedure followed by the Nuclear Metrology Laboratory (Laboratorio de Metrologia Nuclear — LMN) at the IPEN-CNEN/SP, in Sao Paulo, for the standardization in a 4πβ-γ coincidence system and the determination of gamma ray emission probabilities per decay of 166mHo are described. The standardization by means of a 4πβ-γ system was performed selecting two γ-ray windows: one set at the 184 keV total absorption peak and another one covering 700–830 keV energy range, both following β-decay processes. The 166mHo sources were also measured in a ReGe spectrometer previously calibrated with standard sources of 241Am, 133Ba, 57Co, 60Co, 152Eu and 54Mn standardized in the 4πβ-γ coincidence system. The experimental results were compared with data from literature.

The problem of search and rescue in a jungle environment is discussed in this paper. Depending on the relative position between the unknown radio station and the searcher equipment, three propagation mechanisms should be considered in the analysis of the radio path: (a) Both equipments immersed in the jungle; (b) The searcher equipment in a plane or helicopter (ground-to-air link); (c) The searcher equipment on the ground outside the jungle. Once the first two cases are well known, emphasis is given to case (c) where a mathematical model to evaluate the radio wave attenuation is proposed.

In this paper the procedure followed by the Nuclear Metrology Laboratory (Laboratorio de Metrologia Nuclear - LMN) at the IPEN, in Sao Paulo, for the standardization of the 186Re and determination of the gamma emission probabilities per decay of the main gamma-ray energies of 186Re, 137.15 keV from β− decay and 122.6 keV from EC are presented. The activity measurement was carried out in a 4π (PC) β-γ coincidence system. The contribution from electron capture events in the proportional counter has been estimated by means of additional 4π(PC)β-γ HPGe coincidence measurements. The activity of the solution was determined by the extrapolation technique. The events were registered using a Time to Amplitude Converter (TAC) associated with a Multichannel Analyzer. The gamma emission probabilities per decay were determined by means of an HPGe spectrometer calibrated in the 81 keV to 1408 keV energy range, by measuring sealed ampoules of 60Co, 133Ba, 137Cs and 152Eu, standardized at the LMN.

In the present work, a new data acquisition electronic system for 4π²-γ coincidence measurements is proposed which allows simultaneous recording of pulse height and time of occurrence for each nuclear event. The present paper work discusses the conceptual design of the Data acquisition System (DAQ)-based electronic unit that has been specifically developed for this system, focusing on reliability and low cost.