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The transport and vortex pinning properties of nanocomposite YBa2Cu3O7-x (YBCO) film grown by pulsed laser deposition with addition of Ba2 Y(Nb/Ta)O6 (BYNTO) were compared with BaZrO3 added YBCO by DC (long-range vortex motion) and microwave (small-displacement vortex motion) measurement techniques. A high efficiency of BYNTO was observed in the field dependence and in the angular dependence of the critical current density Jc at 77 K, as well as in the field dependence of the complex surface impedance ΔZ. Based on the field dependence of the pinning parameters, such as the pinning parameter r and the pinning constant kp, the vortex pinning regimes were discussed. [ABSTRACT FROM AUTHOR]

A light weight and low-cost active magnetic shield system is proposed for a single channel SQUID-based magnetocardiography system equipped for operating at liquid nitrogen temperature without passive magnetic shield. The developed active shield, using coils around the sensors, is a two-stage magnetic shielding system, each stage of which has been designed to compensate different frequency and dynamic ranges. The sensor part contains two high-Tc rf-SQUID magnetometers, capable of working stably under earth magnetic field, placed in an axial gradiometric arrangement with a baseline of 10 cm. The active shield setup is driven using two correlated proportional-integral-derivative closed loop systems. In the designed system, the coils are in the vicinity of the SQUIDs, resulting in coupling the coils to the SQUIDs as well as to the resonators. Hence, the impedance of the coils along with the phase of the feedback current is affected based on the configuration. In this paper, investigation of the shielding performance of our bi-stage magnetic shield as the active compensation, fed by the optimal feedback control system with all the above considerations, is reported. Using the designed shielding system, the disturbing magnetic signals could be attenuated such that the pico-Tesla signals could be obtained. [ABSTRACT FROM AUTHOR]

The concept of information fusion has gained a widespread interest in many fields due to its complementary properties. It makes systems more robust against uncertainty. This paper presents a new approach for the well-logging estimation problem by using a fusion methodology. The natural gammaray tool (NGT) is considered as an important instrument in the well logging. The NGT detects changes in natural radioactivity emerging from the variations in concentrations of micronutrients as uranium (U), thorium (Th), and potassium (K). The main goal of this paper is to have precise estimation of the concentrations of U, Th, and K. Four types of Kalman filters are designed to estimate the elements using the NGT sensor. Then, a fusion of the Kalman filters is utilized into an integrated framework by an ordered weighted averaging (OWA) operator to enhance the quality of the estimations. A real covariance of the output error based on the innovation matrix is utilized to design weighting factors for the OWA operator. The simulation studies indicate not only a reliable performance of the proposed method compared with the individual Kalman filters but also a better response in contrast with previous fusion methodologies. [ABSTRACT FROM AUTHOR]

A novel multi-mode resonator is presented to design compact tunable balanced bandpass filters (BPFs). From the theoretical analysis, the common-mode (CM) resonant frequencies are different from that of the differential-mode (DM) response, so the CM suppression can be achieved without adding any extra lumped elements. For the DM response, the modal frequencies of odd and even modes can be adjusted simultaneously by varying the varactors. This helps to design the DM response with tunable passband center frequency. Moreover, the even-mode resonant frequency can be tuned independently, leading to controllable passband bandwidth of the DM. To verify the design method, a compact tunable balanced BPF is developed, fabricated and measured. Good agreement can be attained between the measurement and simulation. [ABSTRACT FROM PUBLISHER]