High‐pixel‐rate grating‐light‐valve laser projector

Abstract— A high‐pixel‐rate, high‐contrast (30,000:1) wide‐color‐gamut grating‐light‐valve laser projector is reported. A new optical engine enabling high‐frame‐rate (240 Hz) scan projection is employed. Panoramic wide‐angle‐scan projection with a 64:9 aspect ratio was also developed. Speckle noise is eliminated using a simple but highly efficient technique. The optical throughput efficiency of the grating‐light‐valve laser projector is reviewed.     

An Extension of the Receiver Operating Characteristic Curve and AUC-Optimal Classification

While most proposed methods for solving classification problems focus on minimization of the classification error rate, we are interested in the receiver operating characteristic (ROC) curve, which provides more information about classification performance than the error rate does. The area under the ROC curve (AUC) is a natural measure for overall assessment of a classifier based on the ROC curve. We discuss a class of concave functions for AUC maximization in which a boosting-type algorithm including RankBoost is considered, and the Bayesian risk consistency and the lower bound of the optimum function are discussed. A procedure derived by maximizing a specific optimum function has high robustness, based on gross error sensitivity. Additionally, we focus on the partial AUC, which is the partial area under the ROC curve. For example, in medical screening, a high true-positive rate to the fixed lower false-positive rate is preferable and thus the partial AUC corresponding to lower false-positive rates is much more important than the remaining AUC. We extend the class of concave optimum functions for partial AUC optimality with the boosting algorithm. We investigated the validity of the proposed method through several experiments with data sets in the UCI repository.     

Improvement of component mode synthesis model for vibration analysis of hard disk drives using attachment modes

I improved the component mode synthesis (CMS) model for free and forced-vibration analyses of hard disk drives using attachment modes. The convergence and the accuracy of the proposed CMS model was improved substantially by applying an attachment mode to a FDB shaft and a pivot shaft in the stationary part model. Different formulations were used for the FDBs and the pivot bearings because of their different damping properties. In the proposed formulation, additional general coordinates corresponding to the attachment modes of the FDB shaft are introduced into the system coordinates; on the other hand, the attachment modes of the pivot shaft moderate the stiffness and damping properties of the pivot bearings. To check the improvement of the convergence and the accuracy, I performed the free and forced-vibration analyses using the previous and proposed CMS models and a full finite element (FE) model. The convergence of the natural frequencies and the frequency response function (FRF) of the disk/spindle system were extremely improved. Moreover, the FRF of the head actuator better matched the full FE model than the previous CMS model when the same number of component modes are used.     

A novel spacer‐free panel structure and glass for FEDs

Abstract— A new design for an FED envelope, composed of box‐shaped front glass, sheet‐like rear glass, and metal members, has been devised. This design structure is effective in reducing tensile stress induced by vacuum at the sealing points. Also, a new glass composition, a new physical tempering method, and a lead‐free hermetic sealing material have been developed. As a result, a novel lightweight spacer‐free panel structure for FEDs has been developed by integrating these new technologies. It will assist in maximizing the essential advantages of FED such as high image quality, high reliability, and low cost.     

Core loss in amorphous cut cores with air gaps

The effects of air gaps on the high-frequency core loss in cut cores made of amorphous ribbons are discussed and methods to reduce the core loss in them are proposed. It has been found that the high-frequency core loss in amorphous cut cores with air gaps increases strikingly with increasing air-gap length. The increase in the core loss due to air gaps is remarkable in high-frequency and low-induction range. Measurement of leakage magnetic flux as well as analysis of the flux distribution and the eddy current in an amorphous core with the finite-element method suggests that the increase in the core loss due to air gaps observed in the amorphous cores can be attributed to the in-plane eddy current loss generated by the leakage flux perpendicular to ribbon surfaces. Suppression of the leakage flux normal to ribbon surfaces by using semicircular cores and reduction in width of ribbons of which cores are made decreases the high-frequency core loss in amorphous cut cores with air gaps     

Density estimation with minimization of U-divergence

This paper is concerned with density estimation based on the stagewise minimization of the U-divergence. The U-divergence is a general divergence measure involving a convex function U which includes the Kullback-Leibler divergence and the L ₂ norm as special cases. The algorithm to yield the density estimator is closely related to the boosting algorithm and it is shown that the usual kernel density estimator can also be seen as a special case of the proposed estimator. Non-asymptotic error bounds of the proposed estimators are developed and numerical experiments show that the proposed estimators often perform better than several existing methods for density estimation.     

Development of a high‐resolution RGBW flexible display using a white organic light‐emitting diode with microcavity structure and that of a side‐roll touch panel

In this study, white organic electroluminescent devices with microcavity structures were developed. A flexible high‐resolution active‐matrix organic light‐emitting diode display with low power consumption using red, green, blue, and white sub‐pixels formed by a color‐filter method was fabricated. In addition, a side‐roll touch display was developed in combination with a capacitive flexible touch screen.     

Shock response analysis on thermal stick–slip phenomenon in hard disk drive

We measured and calculated shock responses due to the thermal stick–slip phenomenon in hard disk drives. We first measured the stress wave propagation and found that a stress wave travels over the entire top cover of the drive in 30?μs at two velocities: 4.66 and 2.97?km/s. These are the velocities of longitudinal and distortional waves in a plate, respectively. The position error signal responded in 55?μs after the thermal stick–slip phenomenon happened. We then conducted a numerical analysis of wave propagation. The resultant stress wave propagation and the position error corresponded well to the measured ones. We found that the propagation path which leads overwriting on adjacent tracks is through the actuator to the head, not through the spindle motor to the disk. We concluded that stress waves can be detected with a shock sensor before they arrive at the head if the sensor is located at the pivot bearing or the actuator, which are on the propagation path.     

Robust loss functions for boosting

Boosting is known as a gradient descent algorithm over loss functions. It is often pointed out that the typical boosting algorithm, Adaboost, is highly affected by outliers. In this letter, loss functions for robust boosting are studied. Based on the concept of robust statistics, we propose a transformation of loss functions that makes boosting algorithms robust against extreme outliers. Next, the truncation of loss functions is applied to contamination models that describe the occurrence of mislabels near decision boundaries. Numerical experiments illustrate that the proposed loss functions derived from the contamination models are useful for handling highly noisy data in comparison with other loss functions.