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Pulse width-modulated dc–dc converters are widely used in the renewable power systems. In practice, their reliability is of major concern. To identify the converter system, the Walsh–Hadamard transformation and recursive least square (RLS) methods are used in some previous works. However, the accuracy of the identified parameters is degraded under measurement noise. In this paper, a new approach for the full parameter estimation of a dc–dc buck converter is proposed. The new approach is realized using the biogeography-based optimization. Unlike the traditional RLS method, the proposed method is based on a state-space model with full-state observation. Therefore, the performance of parameter estimation under different measurement noise levels is improved. Both simulation and experimental results are presented to validate the effectiveness of the new estimation scheme. [ABSTRACT FROM PUBLISHER]

A wireless system consisting of a finite number of heterogeneous users transmitting packets over a slotted ALOHA Rayleigh-fading channel is investigated in this paper. In this system, each user tries to minimize its number of transmission attempts while meeting the throughput demand. The user interaction in such an ALOHA network is modeled as a random access game. A novel technique to better exploit the channel state information (CSI) named adaptive CSI transmission method is proposed. Benchmarking with the no-CSI method and threshold-based CSI method, it is revealed that the proposed adaptive CSI method can yield up to 9.9% more throughput and 12.3% power reduction. Two simple yet effective guidelines on selecting among these CSI-related methods are formulated for systems with different SNRs and capture ratios. A distributed algorithm is proposed to find the optimal transmission probability. Both analytical and simulation results show that the algorithm exhibits fast convergence speed and is robustness against changes on the number of active nodes in the network. [ABSTRACT FROM AUTHOR]

The extended Kalman filter (EKF) has been widely used for attitude determination in various satellite missions. However, it requires an extensive computational power that is not suitable for nanosatellite application. This paper proposes a gain-scheduled EKF (GSEKF) to reduce the computational requirement in the nanosatellite attitude determination process. The proposed GSEKF eliminates the online recursive Kalman gain computation by analytically determining the Kalman gain based on the sensor parameters, such as the gyroscope noise variance, the quaternion variance, the observation matrix, and the satellite rotational speed. Two GSEKF Kalman gains for two satellite operating modes are presented: the Sun-pointing and nadir-pointing modes. The simulation and experimental results show that the proposed method has comparable attitude estimation accuracy to the conventional EKF. In addition, the proposed GSEKF reduces 86.29% and 89.45% of the computation load compared with the multiplicative EKF and Murrell?s version. [ABSTRACT FROM AUTHOR]

The present research examined the experiences of individuals who witnessed or knew about ethnic harassment of their coworkers. Through 3 studies, we found that knowledge of other people's harassment was differentiated from personal experiences as a target and was associated with deleterious occupational, health-related, and psychological consequences beyond those accounted for by direct harassment and affective disposition. Ethnicity and gender did not moderate these relationships. Knowledge of others' ethnic harassment can therefore be construed as bystander harassment. Results also indicated that bystander and direct harassment were relatively common occurrences. Both harassment types contributed to how ethnic conflict is experienced. The consequences of ethnic harassment are not restricted to ethnic minority employees. Rather, everyone is at risk from such behaviors. [ABSTRACT FROM AUTHOR]

The present meta-analysis examined the stability of vocational interests from early adolescence (age 12) to middle adulthood (age 40). Stability was represented by rank-order and profile correlations. Interest stability remained unchanged during much of adolescence and increased dramatically during the college years (age 18-21.9), where it remained for the next 2 decades. Analyses of potential moderators showed that retest time interval was negatively related to interest stability and that rank-order stability was less stable than profile stability. Although cohort standings did not moderate stability, interests of the 1940s birth cohort were less stable than those of other cohorts. Furthermore, interests reflecting hands-on physical activities and self-expressive/artistic activities were more stable than scientific, social, enterprising, and clerical interests. Vocational interests showed substantial continuity over time, as evidenced by their higher longitudinal stability when compared with rank-order stability of personality traits, The findings are discussed in the context of psychosocial development. [ABSTRACT FROM AUTHOR]

Investigates the potential of the biomass of non-living water hyacinth roots Eichhornia crassipes as a biosorbent for chromium [Cr(VI)] from synthetic solution and electroplating waste under batch conditions. Factors affecting sorption of chromium; Optimum pH for the sorption.

The performance of a pulsed CO2 laser using the capacitor transfer circuit is generally known to improve with an optimum peaking-to-storage capacitor ratio Cp/Cs which varies from around 0.1 to almost 0.5. There has been no reported attempt to account for precisely the origin of this optimum ratio and the large difference amongst them with different experimental setups. In this paper, the optimum capacitor ratio is shown to depend uniquely on the distributed circuit inductances. This may be understood from a simple consideration of the impedance matching for achieving an optimum power transfer at a quasiconstant E/N ratio into the main discharge. [ABSTRACT FROM AUTHOR]

A simple trigatron spark-gap chamber is modified to accommodate two cascading highvoltage breakdowns, separated by the time lag of the second spark formation. The time lag is employed as a temporal delay for synchronizing the ultraviolet preionization and the main discharge in the transversely excited atmospheric CO[sub 2] laser. Owing to prompt triggering and in situ preionization of the second breakdown, reliable delay up to 500 ns is possible by simply varying the separation of the second spark-gap electrode to that of the first spark gap. [ABSTRACT FROM AUTHOR]

A scheme of pulse based neural circuits for object tracking is proposed. Different from the conventional frame-based methodology, the proposed design utilises parallel arrays of circuits to extract pixels with significant temporal contrast, which are indicators of moving objects. It can be implemented on an FPGA chip in full parallelism and improves the tracking performance dramatically. Moreover, its integrate-and-fire neural model can cluster concave data sets. Experimental results show that the proposed scheme outperforms conventional methods. [ABSTRACT FROM AUTHOR]