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Building structure and other factors lead to the performance deterioration of global postioning system (GPS) positioning systems indoors. An adaptive model for Bluetooth-based indoor positioning is proposed in this paper, targeting at the complex indoor environment, to improve the performance of Bluetooth-oriented indoor positioning systems. More accurate Received Signal Strength Indicator (RSSI) calibration which is optimized via Gaussian filtering, together with the environment-dependent attenuation coefficient optimization, results in a more precise hybrid model in the complicated indoor environment. Experiment results show that the difference between the estimated results and the measured samples is less than 0.25[Formula: see text]m as the target node and reference node is less than 1.5[Formula: see text]m far from each other. As the distance increases to more than 1.5[Formula: see text]m, the relative difference between the estimated values and the measured ones decreases to 7.8% at most, satisfying the requirements for indoor positioning applications.

This paper analyzes the influences of the factors in a capacitor-driven multi-stage synchronous induction coilgun (SICG) and optimal combination of the design parameters based on orthogonal experiment design (OED). Finite element transient solver is used to calculate the motion characteristics of a multi-stage SICG. The muzzle speed is set to be the target of the optimization. System parameters (factors), levels and orthogonal array (OA) are determined by the order. Three optimization schemes are compared, including stage-by-stage optimization, section optimization and full optimization. Optimal combination of the three-stage SICG is obtained, as well as important order of factors. It shows that a set of comparatively better parameters and relatively higher efficiency could be achieved through orthogonal optimum. Wire diameter and coil diameter are the most important factors that influence the system efficiency of the launcher. Besides them, length of coil, trigger position and number of turns have less influence for the system in the important order. Section optimization could reduce the amount of computations compared to full optimization and a set of comparatively better parameters and relatively higher efficiency could be achieved. It is suggested to optimize a multi-stage SICG. How to choose the factors from lots of parameters is according to the engineering practice. Improper choices of the value in levels may cause unable to reach an optimum. The conclusion will be useful for coilgun design.

With the development and increasing use of intelligent vacuum circuit breaker (VCB), the electromagnetic compatibility problem between VCBs and their low-voltage electronic equipment is becoming increasingly prominent. Switching operations of circuit breakers are known to be serious sources of electromagnetic interference (EMI) to their secondary equipment, which can lead to the control and protection devices display error and malfunction. Hence, it is very important to study the EMI problem of the secondary equipment (such as current transformer (CT), PT, and controller) caused by the operations of circuit breakers. This paper carried out the tests of a 10 kV medium-voltage outdoor polemounted switch by a synthetic test circuit with large current and high impulse voltage sources, and collected the current signals of the secondary circuit at the same time, then obtained the frequency and energy distributions of the disturbance signals, caused by the breaking operation of pole-mounted switch, by time and frequency characteristic analysis with the wavelet analysis. Results show that the secondary side of the CT and the feeder terminal unit (FTU) controller are bearing EMI when pole-mounted switch is in operation and the distribution of the frequency spectrum is wide. The most serious disturbance appears at the time of arc current passing zero and the frequency distribution is mainly in 7.81-15.63 MHz. The EMI caused by transient recovery voltage is mainly distribution in 31.25-125.0 MHz. The maximum amplitude of disturbance pulses is about 4.5 times as large as that of the normal case. The results can provide a reference to the measures against the EMI for the pole-mounted switch's FTU controller. Index Terms-Current transformer (CT), electromagnetic interference (EMI), feeder terminal unit (FTU), frequency distribution, pole-mounted switch, synthetic test, transient recovery voltage (TRV), wavelet analysis.