We have proposed a novel educational system named the active textbook (hereafter A-txt) system. A-txt system consists of an ordinary paper-based textbook, a general portable electronic terminal with a camera like a smartphone and application software for the system. A normal textbook can be evolved into a digital one through the attachment of additional digital information and all kinds of digital contents such as movie, animation, 3D CG and so on will be available. The teachers who use the system can create contents for A-txt freely without expertise about information technology. The introduction cost is relatively low, because the mobile terminal for students may be their owned general-purpose type, not special-purpose type, and authored educational materials do not need particular software. For the reasons above, the system has a large possibility to spread in multiple educational fields and it can be easy for students to understand several subjects into which the system is introduced.

Photonic networks based on wavelength division multiplexing (WDM) and optical path technologies are expected to realize flexible, transparent, and cost-effective transport networks with a large transmission capacity. This paper explores the design framework of photonic transport networks taking into consideration the operation administration and maintenance (OA&M) functions required for the successful introduction of WDM systems based on the optical path concept. From the view point of network maintenance, clear distinction is made between the optical path layer and the optical section layer to facilitate accurate and smooth failure localization. The digital multiplexing span between physical multiplexing interfaces at the end-to-end digital nodes should have the same maintenance span as the corresponding optical path. We argue that cooperative maintenance by OA&M functions at both the digital and optical layers can be a practical way of network supervision. A supervisory (SV) signal transfer method and a configuration that is suitable for the terrestrial trunk network are also indicated. As an example, a practical SV system design methodology and an actual procedure developed for a single channel optical transmission system based on optical in-line amplifiers are introduced. Furthermore, application of the developed SV system and network restoration schemes is discussed for future WDM-based photonic networks. The OA&M aspects introduced will be valuable for creating future photonic network systems.

A computational scheme is presented for obtaining a characteristic description of a free-form curved surface from 3-D range images whose natural modes are in the form of level (equidistance) contours. The novelty in this scheme is that dense surface contours are used to directly estimate the surface curvatures in a systematic fashion without having to explicitly or implicitly compute any partial derivatives. The principle of the scheme is described, and the framework of computational paradigm is outlined for a shape description (shape from level contours) of the free-form curved object from its local surface properties. The objective is to obtain an invariant viewpoint and stable representation that is useful in 3-D object reconstruction and recognition. Although the scheme is based on analysis of level contours, the computation model for shape representation is general and applicable to any dense range image.>

In order to create a 3-D system with two images (right and left) that must be transmitted simultaneously, an efficient coding appropriate for stereoscopic images must be developed to reduce the large amount of information contained in the images. As an initial step in realizing such a coding scheme, the statistical characteristics of stereoscopic images and the possibility of stereoscopic image data compression utilizing the cross correlation between the right and left images are considered. The results indicate that data compression is possible by shifting one image horizontally and subtracting it from the corresponding area of the other. Experiments to compare the capability of generating disparity by stereoscopic TV images and human stereoscopic vision have been performed. The results indicate that data compressions without 3-D image deterioration is possible by reducing high-spatial-frequency disparity above 3 cycles/degree. It is concluded that efficient image coding for stereoscopic images can be achieved by utilizing the correlation between two images and human stereopsis characteristics, making possible low-cost, more realistic 3-D visual communication.>

Algorithms are presented for extracting clear deformed gratings and exact contour lines of an object, along with theoretical analysis and experimental results. The algorithm extracts of the exact contour lines and thins traces and matches of the original and the p/4 phase-shifted moire fringes at the same time, allowing a clear determination of convex and concave parts and their relative order. Experimental results for contour line extraction are shown. Compared with conventional algorithms, the present method shows much improved results.>

This paper presents the design and performance features of a successfully developed optical intraoffice transmission system operating at 100-400 Mbits/s. The keys to the commercial realization of this simple, highly reliable, and low-cost system are the employment of the 1.3 μm LED and graded-index multimode fiber. Additionally important, the system makes use of coded mark inversion (CMI) coding to ensure bit sequence independence (BSI) and good error-monitoring capability. Experimental results have clarified the optimum bandwidth of the low-pass filter at the receiver end and the commercially attainable transmission distance. Furthermore, an available system gain of 15.4 dB is demonstrated through 400 Mbit/s transmission experiments. This value enables transmission over distances in excess of 4 km through multimode fiber (900 MHz\cdotpkm, 0.8 dB/km).

This paper introduces a repeater fault location system for a repeated submarine optical fiber transmission system of 400 Mbits/ s at 1.3μm. The repeater fault location system is used in an out-of-service test. The fault locator transmits a test signal via a main optical fiber line, in order to make a loop-back path in one of the repeaters for returning the test signals via another main optical fiber line and to measure the bit error rate (BER) of the interrogated repeater. The test signal is a kind of pseudorandom signal that includes a low frequency component, which is assigned to the repeater as a supervisory frequency tone (SVT) signal. The BER is measured by counting the number of low frequency signal phase inversions in a time. This paper first describes the test signal generating method, SVT frequency allocation, and the filter design installed in a repeater. Next, there is a discussion of how the capability of the repeater fault locator has been experimentally verified by using two submarine repeaters, including four regenerative repeater units and three submarine optical fiber cables. As a result, a BER of less than5 \times 10^{-6}is accurately measured.

This paper introduces a correlation technique in order to accurately measure intermodulation products from repeaters within a short period of time. A pair of PN sequences, whose cross-correlation function has a zero sidelobe has been designed to reduce interference by other products, and to obtain the necessary signal-to-noise ratio (more than 50 dB). As an example, design objectives and results for a repeater fault locator in a 140 MHz submarine coaxial cable system are described.