A novel depth perception control method for a monocular head-up display (HUD) in a car has been developed, which is called the dynamic perspective method. The method changes a size and a position of the HUD image such as arrow for depth perception and achieves a depth perception position of 120 [m] within an error of 30% in a simulation. However, it is difficult to achieve an accurate depth perception in the real world because of car vibration. To solve this problem, we focus on a property, namely, that people complement hidden images by previous continuously observed images. We hide the image on the HUD when the car is vibrated very much. We aim to point at the accurate depth position by using see-through HUD images while having users complement the hidden image positions based on the continuous images before car vibration. We developed a car that detects big vibration by an acceleration sensor and is equipped with our monocular HUD. Our new method pointed at the depth position more accurately than the previous method, which was confirmed by t-test.

The stochastic behavior of inter-core crosstalk in multi-core fiber is discussed based on a theoretical model validated by measurements, and the effect of the crosstalk on the Q-factor in transmission systems, using multi-core fiber is investigated theoretically. The measurements show that the crosstalk rapidly changes with wavelength, and gradually changes with time, in obedience to the Gaussian distribution in I-Q planes. Therefore, the behavior of the crosstalk as a noise may depend on the bandwidth of the signal light. If the bandwidth is adequately broad, the crosstalk may behave as a virtual additive white Gaussian noise on I-Q planes, and the Q-penalty at the Q-factor of 9.8dB is less than 1dB when the statistical mean of the crosstalk from other cores is less than -16.7dB for PDM-QPSK, -23.7dB for PDM-16QAM, and -29.9dB for PDM-64QAM. If the bandwidth is adequately narrow, the crosstalk may behave as virtually static coupling that changes very gradually with time and heavily depends on the wavelength. To cope with a static crosstalk much higher than its statistical mean, a margin of several decibels from the mean crosstalk may be necessary for suppressing Q-penalty in the case of adequately narrow bandwidth.

This study investigated the distribution of attention to frontal space in augmented reality (AR). We conducted two experiments to compare binocular and monocular observation when an AR image was presented. According to a previous study, when participants observed an AR image in monocular presentation, they perceived the AR image as more distant than in binocular vision. Therefore, we predicted that attention would need to be shifted between the AR image and the background in not the monocular observation but the binocular one. This would enable an observer to distribute his/her visual attention across a wider space in the monocular observation. In the experiments, participants performed two tasks concurrently to measure the size of the useful field of view (UFOV). One task was letter/number discrimination in which an AR image was presented in the central field of view (the central task). The other task was luminance change detection in which dots were presented in the peripheral field of view (the peripheral task). Depth difference existed between the AR image and the location of the peripheral task in Experiment 1 but not in Experiment 2. The results of Experiment 1 indicated that the UFOV became wider in the monocular observation than in the binocular observation. In Experiment 2, the size of the UFOV in the monocular observation was equivalent to that in the binocular observation. It becomes difficult for a participant to observe the stimuli on the background in the binocular observation when there is depth difference between the AR image and the background. These results indicate that the monocular presentation in AR is superior to binocular presentation, and even in the best condition for the binocular condition the monocular presentation is equivalent to the binocular presentation in terms of the UFOV.

A number of Tonpilz piezoelectric transducers generally form a large matrix array. They may be required to be only light in weight, or both miniaturized and light in weight as well as to have high-power capability, according to their use. This paper describes the results obtained in an investigation of miniaturized, light-weight Tonpilz piezoelectric transducers with high-power capability. An electromechanical energy conversion system and mechanical vibration system for the transducer are theoretically investigated on transducer configuration, using a Martin equivalent circuit and distributed-constant equivalent mechanical circuits. For simplification of the theoretical analysis, the transducer was considered as being divided into a front-half section, from the head mass end to the vibration nodal section, and a rear-half section, from the vibration nodal section to the tail mass end. Figures of merits, FMm for the front-half section and FM'm for the rear-half section, are calculated to achieve lightening as well as high-power capability. In addition, figures of merits FMml for the front-half section and FM'ml for the rear-half section are calculated to achieve miniaturization and lightening as well as high-power capability. To corroborate the theoretical results obtained, three kinds of Tonpilz transducers having the same 30 kHz resonant frequency but different configurations were built. Then, three kinds of 33 matrix arrays composed of nine Tonpilz transducers with the same configuration were fabricated. To evaluate the high-power characteristics for the arrays, a water tank to which high hydraulic pressure can be applied was adopted and a high-power test was carried out. As a result, it was found that transducers with high FMm and FM'm figures of merits are light in weight and exhibit high performance in high-power handling capability. Also, it was found that transducers with high FMml and FM'ml figures of merits are miniaturized and light in weight and exhibit high performance in high-power handling capability.

Tonpilz piezoelectric transducers are one style of transducers for high-power sound generation. However, the transducers have mainly been designed by the trial-and-error method. The object of this paper is to precisely estimate the transducer performances beforehand by a equivalent circuit analysis. The precise electro-mechano-acoustical equivalent circuit is derived for the transducer, including housing, an acoustic rubber layer and a bolt, and its transmission matrix is presented. To improve the calculation accuracy, the effects of adhesive layers in a piezoelectric ceramic stack part and compressive stress by bolting them together are included into the electrical and mechanical equivalent constants for the ceramic stack. Also, to accurately evaluate any errors between theoretical values and measured values, transducer performances are expressed as absolute values by MKS units. Then, based on this analysis, a Tonpilz transducer has been built. Transmitting and receiving voltage sensitivities for the transducer, as well as the respective resonant frequencies, mechanical quality factors and free admittance loci in air and in water, have been measured. As a result, a good agreement between theoretical values and experimental results has been achieved.

This paper focuses on the power of comments to predict fault-prone programs. In general, comments along with executable statements enhance the understandability of programs. However, comments may also be used to mask the lack of readability in the program, therefore well-written comments are referred to as “deodorant to mask code smells” in the field of code refactoring. This paper conducts an empirical analysis to examine whether Lines of Comments (LCM) written inside a method's body is a noteworthy metric for analyzing fault-proneness in Java methods. The empirical results show the following two findings: (1) more-commented methods (the methods having more comments than the amount estimated by size and complexity of the methods) are about 1.6 - 2.8 times more likely to be faulty than the others, and (2) LCM can be a useful factor in fault-prone method prediction models along with the method size and the method complexity.

In this paper we report on an approach inspired by Ant Colony Optimization (ACO) to provide a fault tolerant and efficient means of transferring data in dynamic environments. We investigate the problem of distributing data between a client and server by using pheromone equations. Ants choose the best source of food by selecting the strongest pheromone trail leaving the nest. The pheromone decays over-time and needs to be continually reinforced to define the optimum route in a dynamic environment. This resembles the dynamic environment for the distribution of data between clients and servers. Our approach uses readily available network and server information to construct a pheromone that determines the best server from which to download data. We demonstrate that the approach is self-optimizing and capable of adapting to dynamic changes in the environment.