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With the Global Positioning System (GPS), it is possible to estimate the baseline vectors between several GPS antennas (with fixed positions on a vehicle) and so, the attitude can be determined. To achieve this, the precise carrier phase measurements are used, however, these measurements have the so called phase ambiguities (integer number of cycles) that need to be solved. When only single-frequency measurements (L1 band) are used, the method known as Ambiguity Filter is employed, after the search method LAMBDA, to stabilize the obtained solution. The leverage of the Ambiguity Filter, relatively to the alternative of using only the LAMBDA method, comes from using a prior knowledge of the baseline length in the ambiguity resolution problem, which the LAMBDA does not. Preliminary tests with the implementation of the Ambiguity Filter have shown that its performance is very sensitive to the precision with which the baseline length is known. This was the main motivation for the work here presented. The results presented in this paper are based on field tests, conducted at the university campus, with two GPS receivers in a static, fixed length, baseline configuration.

The Global Positioning System (GPS) can be used to estimate the attitude of a vehicle. To do this, multiple receivers should be used with the antennas in known fixed positions in the vehicle body frame. Since the estimation of the attitude angles needs high precision, the carrier phase measurements (with millimeter precision) are used in combination with the pseudorange measurements. Nevertheless, the phase measurements have the disadvantage of having an unknown integer number of cycles, known as phase ambiguities. When low-cost receivers with single-frequency measurements (L1 band) are used, the method called Ambiguity Filter must be applied to stabilize the solution given by the LAMBDA method. This filter makes use of the prior knowledge of the distance between the antennas. If the Ambiguity Filter fixes an incorrect set of ambiguities, the solution for the baseline (and attitude angles) starts to degrade, which may not be immediately visible. This paper proposes a new implementation within the Ambiguity Filter in order to improve the detection of false locks for the solution of the phase ambiguities. This implementation also decreases the Ambiguity Filter sensitivity to the value of the baseline length that is given as input to this method. The results presented in this paper were based on field tests performed in static conditions with a single-baseline setup in the university campus, allowing the estimation of heading and pitch.

High resolution γ-ray spectroscopy measurements at MHz counting rates were carried out at nuclear accelerators, combining a LaBr 3 (Ce) detector with dedicated hardware and software solutions based on digitization and post-mortem analysis. Spectra were reconstructed at counting rates up to 4 MHz, with little or no degradation of the energy resolution. The reported results represent a step forward towards the final goal of γ-ray spectroscopy measurements on a burning plasma device.

In this paper, the Model Reference Adaptive Control (MRAC) with dead-zone compensation is proposed to improve two MRAC variations: MRAC with fixed adaptive gain (γ) and MRAC with variable γ based on η-adaptive optimization algorithm. The proposed MRAC is often used to compensate the dead-zone effect on valve that is not taken into consideration in the usual MRAC. It was also implemented a compensation in inverse dynamic on dead-zone. The nonlinearity inverse model is estimated by method of Recursive Least Squares (RLS). All comparisons and validations were made based on results collected from a simulation and developed in accordance with two models: a simplified Hammerstein model and a phenomenological model of Wiener. To verify the proposed controllers with inverse compensation performance we applied to a pH neutralization process. Simulations have been presented to confirm the effectiveness of the technique.