Storage of multiple holograms of equal diffraction efficiency in a phase-code multiplexing system

Computer simulations of 8-, 32-, and 128-bit phase-code multiplexing systems are presented, and exposure schedules are obtained numerically for equal diffraction efficiency. An analytic prediction of the exposure schedule is derived as a double exponential function that can be applied to the three different systems for variation of diffraction efficiency of less than +/- 13.5%. Eight holograms were experimentally recorded in a BaTiO3 crystal according to our exposure schedule and also to conventional schedules, which had originally been derived for an angle-multiplexing system. It is shown that the experimental data agree well with the computer simulations.     

A study on the student pilot's mental workload due to personality types of both instructor and student

The main purpose of this paper is to provide the ideal flight crew combination for instructor and student pilots in order to enhance the flight training effects based on Myers Briggs Type Indicator (MBTI) theory. In addition to personality, various levels of flight difficulty are considered in order to investigate their potential interaction effect in terms of student pilots' mental workload measured in heart rate, altitude deviation, NASA-TLX (Task Load Index) and subjective degree of personality harmony. Based on an experiment performed in a real flight situation, we found significant effects of personality combinations in terms of all four outcome measures. Both group C types of instructors and students who are concrete, realistic and have mechanical skills turn out to be the ideal flight crew combination. A structural equation model, fitted to analyse causality among the four response variables, implied that as the heart rate increased, the altitude deviation increased. In addition, as the altitude deviation and personality harmony increased, NASA-TLX increased. The results of this study are expected to provide a theoretical basis for manning the flight crew combinations and thereby enhancing the efficiency of flight training.     

Controlled crystallization and characterization of cordierite glass-ceramics for magnetic memory disk substrate

Glass-ceramics containing cordierite (2MgO-2Al₂O₃-5SiO₂) as a crystal phase based on the glasses in the system MgO-Al₂O₃-SiO₂ were investigated for the application to magnetic disk substrate for higher storage capacity. Parent glasses were prepared with CeO₂ addition as a flux and were crystallized by a controlled 2-step heat treatment The maximum nucleation and crystal growth rates were 2.4 × 10⁹/mm³ · hr at 800 °C and 0.3 m/hr at 915°C respectively. Only - cordierite was precipitated after heat-treatment. After nucleation at 800 °C for 5 hours prior to crystallization at 915 °C for 1 hour, the resulting crystal volume fraction and crystal size were 17.6% and 0.3 m, respectively. Heat-treated specimens through the above condition showed the optimum properties for magnetic memory disk substrates as follows.; Bending strength of 192 MPa, Vickers hardness of 642.1 kg/mm², thermal expansion coefficient of 39 × 10^–7/K and surface roughness of 27 Å.     

Experimental study for the comparison of classifier combination methods

In this paper, we compare the performances of classifier combination methods (bagging, modified random subspace method, classifier selection, parametric fusion) to logistic regression in consideration of various characteristics of input data. Four factors used to simulate the logistic model are: (a) combination function among input variables, (b) correlation between input variables, (c) variance of observation, and (d) training data set size. In view of typically unknown combination function among input variables, we use a Taguchi design to improve the practicality of our study results by letting it as an uncontrollable factor. Our experimental study results indicate the following: when training set size is large, performances of logistic regression and bagging are not significantly different. However, when training set size is small, the performance of logistic regression is worse than bagging. When training data set size is small and correlation is strong, both modified random subspace method and bagging perform better than the other three methods. When correlation is weak and variance is small, both parametric fusion and classifier selection algorithm appear to be the worst at our disappointment.     

Patterns of self-disclosure in psychotherapy and marriage.

This study compared patterns of self-disclosure in psychotherapy and marriage. Participants (48 married, current psychotherapy patients, mean age = 42) completed a 101-item Disclosure to Therapist Inventory and a companion measure, a 101-item Disclosure to Spouse Inventory. Results indicated a pattern of greater disclosure to one's therapist in regard to issues involving despair (e.g., feelings of depression), and to one's spouse in regard to procreation and body concerns (e.g., birth control) and values (e.g., feelings about religion, race, or politics). Issues involving sex were infrequently discussed in either context. Discrepancy scores (differences between extent of disclosure and perceived importance) were greater in the spouse condition. Outcome predictors varied by situation, with overall disclosure predicting therapeutic outcome and both overall disclosure and discrepancy scores predicting marital satisfaction. Findings suggest that although there is substantial overlap in issues discussed in these two contexts, certain intimate disclosures are perceived as situation-specific. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modified Notch Filter-based Instantaneous Phasor Estimation for High-speed Distance Protection

A novel method for estimating the instantaneous phasor of a fault current signal is proposed for high-speed distance protection immune to a DC-offset. The method uses a modified notch filter in order to eliminate the fundamental frequency component from the fault current signal. Since the output of the modified notch filter is the delayed DC-offset, delay compensation results in the same waveform as the original DC-offset. Subtracting the obtained DC-offset from the fault current signal yields a sinusoidal waveform, which becomes the real part of the instantaneous phasor. The imaginary part of the instantaneous phasor is based on the first difference of the fault current signal. Since a DC-offset also appears in the first difference, the DC-offset is removed from the first difference using the results of the delay compensation. The performance of the proposed method was evaluated for a–phase to ground faults on a 345 kV 100 km overhead transmission line. The Electromagnetic Transient Program was used to generate fault current signals for different fault locations and fault inception angles. The performance evaluation showed that the proposed method can estimate the instantaneous phasor of a fault current signal with high speed and high accuracy. The paper concludes by describing the hardware implementation of the proposed method on a prototype unit based on a digital signal processor.     

Parametric GLRT for Multichannel Adaptive Signal Detection

This paper considers the problem of detecting a multichannel signal in the presence of spatially and temporally colored disturbance. A parametric generalized likelihood ratio test (GLRT) is developed by modeling the disturbance as a multichannel autoregressive (AR) process. Maximum likelihood (ML) parameter estimation underlying the parametric GLRT is examined. It is shown that the ML estimator for the alternative hypothesis is nonlinear and there exists no closed-form expression. To address this issue, an asymptotic ML (AML) estimator is presented, which yields asymptotically optimum parameter estimates at reduced complexity. The performance of the parametric GLRT is studied by considering challenging cases with limited or no training signals for parameter estimation. Such cases (especially when training is unavailable) are of great interest in detecting signals in heterogeneous, fast changing, or dense-target environments, but generally cannot be handled by most existing multichannel detectors which rely more heavily on training at an adequate level. Compared with the recently introduced parametric adaptive matched filter (PAMF) and parametric Rao detectors, the parametric GLRT achieves higher data efficiency, offering improved detection performance in general.     

A Structural Solution to Communication Dilemmas in a Virtual Community

In a many-to-many communication setting like a virtual community, individuals may be strongly tempted to free-ride on others' contributions, which would eventually lead to the collapse of the community. To find a structural solution to the "communication dilemma," this study compared the performances of 2 communication structures—one based on the interpersonal networks (network-generalized exchange: N_EX; e.g., blogs) and the other based on a public electronic bulletin board (group-generalized exchange: G_EX). In a 2 × 2 × 2 longitudinal between-subject experiment, it was found that changing G_EX to N_EX could increase the contributions made by individuals. Furthermore, N_EX was found to be an effective structure for N-person communication particularly when a large number of individuals were involved. The findings imply that an individual's cooperative motivation is a function of the incentive structure of a particular form of information exchange, which means that altering the exchange form may be a possible solution to the communication dilemmas in virtual communities.     

Evaluating the calibration of MTSAT‐1R infrared channels using collocated Terra MODIS measurements

The calibration of four MTSAT‐1R infrared channels was evaluated by comparing MTSAT measurements with Terra/MODIS inferred MTSAT‐equivalent brightness temperatures during August 2005 and August 2006. Theoretical relationships converting MODIS brightness temperatures to MTSAT‐equivalent values were obtained and used for the comparison. Results indicate that MTSAT two split window channels are well calibrated, and no serious systematic errors or biases are found; and the MTSAT water‐vapour channel shows a good linear relationship but with a warm bias up to 2 K. The significant cold bias of MTSAT 3.7 µm channel about ?6.7 K in August 2005 is found to be much removed in August 2006, after correction of the electrical crosstalk between MTSAT‐1R SWIR channel and WV channel starting from March 2006. Since then, calibration performances of MTSAT‐1R split window channels and shortwave IR channel seem to be comparable with MODIS calibration, while the water‐vapour channel shows more uncertainties up to 2 K of bias.     

Bayesian network analysis for the dynamic prediction of early stage entrepreneurial activity index

Entrepreneurship plays a critical role for the development and well-being of society. Illustration of its dynamic relationship with entrepreneurial attitudes and aspirations can provide a guideline for the cause of such activities. However, a time-lagged causal relationship among these concepts has not yet been established. In this study, we examine a dynamic relationship among early stage entrepreneurial attitudes, activities, and aspirations using Bayesian network (BN) analysis. In addition, we propose an early stage entrepreneurial activity index that can predict the percentage of both nascent entrepreneur and new business owner using the variables related to entrepreneurial attitudes of the previous year. This index, in turn, can be used to predict various aspects of entrepreneurial aspiration of the following year. The proposed index turns out to have very high prediction accuracy and is expected to provide effective policies to boost future entrepreneurial activity and aspiration.