Uma estratégia para otimizar a geração de arranjos em subestações virtuais de energia elétrica

The Virtual Reality techniques applied in Electricity Environments provide a new supervisory control paradigm. The fact of existing a virtual environment (VE), geometrically similar to a real substation, reduces the difference of mental models built by field operators compared with those built by system center operation improving the communication. Beside this, those systems can be used as visualization interfaces for electricity system simulators, training systems for professors and undergraduate students, field operators and maintenance professionals. However, the development process of these systems is quite complex, combining several activities such as implementation, 3D modeling, virtual sceneries construction, usability assessment and management project techniques. In this context, this work present a GUI strategy to build field arrangements based on scene graphs, to reduce time in Virtual Electricity Substations Arrangement development. Through this, mistakes during the VE building can be avoided making this process more reliable. As an concept proof, all toolkits developed in this work were applied in the virtualization of the substations from a Brazilian power concessionary named CEMIG.

Avaliação das condições de precipitação do azul da Prússia sobre pó de grafite visando o desenvolvimento de eletrodos de pasta de carbono para a quantificação de nitrito

An amperometric FIA method for nitrite quantification based on nitrite electroreduction and employing a carbon paste electrode (CPE) chemically modified with iron hexacyanoferrate (HCF) as an amperometric detector was developed. The influence of experimental conditions on the preparation of the electrode materials was evaluated and the materials obtained in each study were used for the development of modified electrodes. The electrochemical sensors were prepared by a fast, simple, and inexpensive procedure, and the long-term performance of the electrodes were quite satisfactory as the stability was maintained over one year. HCF was an effective redox mediator for nitrite electroreduction in acidic media, allowing nitrite detection at +0.2 V vs. Ag/AgClsat, which is a potential free of possible interfering species that are normally present in food and water samples. The electrochemical cell used in the FIA system was similar to a batch injection analysis cell, enabling recirculation of the carrier solution. This is an attractive feature because it allows the use of a high flow rate (6 mL min-1) leading to high sensitivity and analysis speed, while keeping reagent consumption low. The proposed method had a detection limit of 9 μmol L-1 and was successfully employed for nitrite quantification in spiked water and sausage samples. The obtained results were in good agreement with those provided by the spectrophotometric official method. At a 95 % confidence level it was not observed statistical differences neither in nitrite content nor in the precision provided by both methods. The experimental conditions for the synthesis of HCF were optimized and the best electrode material was prepared by mixing FeCl3, K4[Fe(CN)6] and carbon powder subjected to an acid and thermal treatment (400 ºC), followed by ultrasonic agitation at 4 °C. This material was used to construct an electrode with improved analytical performance to reduce nitrite, which presented greater stability compared to HCF film electrodeposited on the EPC, showing that the preparation procedure of the electrode material is an effective strategy for the development of HCF modified electrodes.

Desenvolvimento de um exoesqueleto para movimentação/reabilita-ção de paraplégicos

People bedridden by paralysis/motor disability are subject to several problems due to lack of movement. Then, it is necessary to use equipments that enable the people bedridden stand up and walk, so as to reduce the problems due to lack of movement and the time of rehabilitation, impacting directly on its quality of life. The aim of this work is the development of an exoskeleton to make the movement of people with paralysis / motor impairment in the lower limbs, without help of third parties, to be activated by the user. To provide support, stability and security to the deficient, it was decided to use a structure formed by four legs, being each leg consisting of a parallel chain. The gait was obtained by combining the movement of two mechanisms: crank/rocker, responsible for oscillatory motion of the leg, and cam/follower, responsible for the foot motion on the desired trajectory. To achieve the aim of this work was conducted a study about the types of exoskeletons for locomotion/rehabilitation of people with lower limb paralysis and presented a study on the movement of the lower limb joints. It also presented a mathematical model to obtain the desired path to the foot of the exoskeleton, the static model and the design of the structure elements. In the sequence is presented the simulation of movements of a people during the human gait, experimental tests and the comparison with the human gait developed by a people without disabilities.

Desenvolvimento do capim-marandu com altura fixa ou variável durante as estações do ano

Aimed to identify, for assessing the tillering dynamics and morphogenesis , strategy (s ) suitable ( s) defoliation management to optimize the appearance of tillers and biomass of Urochloa Brizantha syn. Brachiaria brizantha cv. Marandu ( marandugrass ) throughout the year. The experiment was conducted from January 2013 to May 2014 were studied three strategies defoliation: Marandugrass with 30 cm throughout the experimental period (constant height); Marandugrass 15 cm in winter, the spring 30 cm and 45 cm in summer (increasing height); and Marandugrass 45 cm in winter, the spring 30 cm and 15 cm in summer (descending height). The experimental design was completely randomized in a split plot in time, with four replications. In winter, in the spring and summer, the following variables were calculated: appearance rate (TApP), mortality (TMoP) and survival (TSoP) of tillers, balance (BAL) between TApP and TMoP, stability index (IE) numbers of tillers and leaf elongation rates and stem, length of leaf blade and stem, leaf senescence rate, phyllochron and duration of life of the sheet. The TAPP was higher in the early spring and summer. For TMoP, the highest values were in the late spring and summer. The balance between TApP and TMoP was negative in winter and late spring, regardless of defoliation strategy. There was no difference in IE between the heights of the canopy during winter and late spring .. The number of tillers was higher in early spring and summer and lower in winter and late spring. The defoliation strategies have not changed phyllochron, leaf elongation rate. In spring and summer, there were increases in the rates of appearance, elongation and leaf senescence and, furthermore, decreased life span and phyllochron sheet. The plant height with increasing showed a lower rate of senescence and lower culm length in the spring. To increase the number of tillers marandu, it is advantageous to handle the plant with increasing height, ie, 15 cm in autumn and winter, the spring 30 cm and 45 cm in summer.The maintaining of B. brizantha cv. Marandu with fixed height of 30 cm or with variations between 15 and 45cm from the fall/winter to summer, does not influence the appearance and the growth of leaves per tiller, which indicates great flexibility on management defoliation in this forage plant.