Fundamentals of parametric processing in highly nonlinear optical fiber are reviewed. Experimental procedures necessary for construction of one- and two-pump parametric amplifier architectures are described. Pump phase broadening, dispersion fluctuation and birefringence form basic impairment mechanisms in fiber parametric devices and are analyzed in two-pump parametric devices. Parametric signal processing is introduced with specific applications in all-optical regeneration, band conjugation, multicasting, packet switching and signal distortion reversal.

Most of commercial websites provide customers with menu-driven navigation and keyword search. However, these inconvenient interfaces increase the number of mouse clicks and decrease customers' interest in surfing the websites. To resolve the problem, we propose an information retrieval assistant using a natural language interface in online sales domains. The information retrieval assistant has a client-server structure; a system connector and a NLP (natural language processing) server. The NLP server performs a linguistic analysis of users' queries with the help of coordinated NLP agents that are based on shallow NLP techniques. After receiving the results of the linguistic analysis from the NLP server, the system connector interacts with outer information provision systems such as conventional information retrieval systems and relational database management systems according to the analysis results. Owing to the client-server structure, we can easily add other information provision systems to the information retrieval assistant with trivial modifications of the NLP server. In addition, the information retrieval assistant guarantees fast responses because it uses shallow NLP techniques. In the preliminary experiment, as compared to the menu-driven system, we found that the information retrieval assistant could reduce the bothersome tasks such as menu selecting and mouse clicking because it provides a convenient natural language interface.

This paper demonstrates an on-chip di/dt detector circuit. The di/dt detector circuit consists of a power supply line, an underlying spiral inductor and an amplifier. The mutual inductor induces a di/dt proportional voltage, and the amplifier amplifies and outputs the value. The measurement results show that the di/dt detector output and the voltage difference between a resistor have good agreement. The di/dt reduction by a decoupling capacitor is also measured using the di/dt detector.

A compromising technique is proposed for deterring clients from cheating by robot players in skill-based real-time network games. This technique is to inject a fair random noise into the manual input for a real-time game modeled as a chaotic dynamical system. The fair random noise is determined by means of the bit commitment protocol so that neither host nor client can control the noise in their favor. A scenario possibly plotted by a robot player for its victory may be spoiled by slight noise injection because of the sensitivity of chaotic systems to the input. The noise injection brings a luck-based factor into a skill-based game. In this sense, the technique proposed in this paper is not a solution but a compromise for the inherent problem of robot players with the skill-based network games. An example implementation of pinball is presented.

A new inductance extraction technique of spiral inductor from measurement fixture is presented. We propose a scalable expression of parasitic inductance for interconnects, and design consideration of test structure accommodating spiral inductor. The simple expression includes mutual inductance between the interconnects with high accuracy. The formula matches a commercial field solver inductance values within 1.4%. The layout of the test structure to reduce magnetic coupling between the spiral and the interconnects allows us to extract the intrinsic inductance of spiral more accurately. The proposed technique requires neither special fixture used for measurement-based method nor skilled worker for precise extraction with the analytical technique used.

This paper describes improvement of the gain in the Er-doped lithium niobate waveguide optical amplifiers. A new configuration is proposed, which is loaded with a high-index cladding for the purpose of realizing a larger overlap between the guided light fields and doped Er ion-concentration. It is shown by theoretical simulations and also by experiments that the clad is advantageous to shifts of the light fields toward the substrate surface, and that the overlap between the light field and Er ion-concentration becomes large. Improved optical gains are measured for a fabricated device with a thin-TiO2 clad in the LiNbO3 substrate.

The frequent and time-independent packet loss due to signal noise in the wireless network has been a major obstacle in providing a persistent end-to-end bandwidth in the integrated environment of wired and wireless networks. One approach to cope with this is to develop an efficient transport mechanism which appropriately adapts to the dynamics of the wireless part of the network so that the end-to-end throughput is maximised. The success of new transport mechanisms depends on the quality of information obtained, in particular, from the wireless network. This paper presents a novel mechanism to assess accurately the transmission quality of the wireless part of the integrated CDMA2000 1X networks using the NAK rate obtained from the underlying RLP protocol stack. The experiment results show that the proposed mechanism correctly measures the wireless transmission quality of the CDMA2000 1X network.

We present and demonstrate a novel method of generating a π phase-alternated return-to-zero (RZ) signal together with pulse-amplitude equalization in a rational harmonic mode-locked fiber ring laser, by using a dual-drive Mach-Zehnder modulator. By adjusting the voltages applied to both arms of the modulator, amplitude-equalization and π phase shift can be achieved successfully at a 9.95 GHz repetition rate. The generated alternate-phase RZ signals show enhanced transmission performance in the single-mode fiber (SMF) links without dispersion compensation.

In this paper, a cycle-based network recovery method for optical mesh networks is studied. The study in this paper concentrates on improving two performance requirements on network recovery: efficient spare resource utilization, and robustness for multiple failures. The proposed method uses multiple ring-covers and performs distributed link restoration using preplanned logical cycles embedded in physical mesh topologies. This method provides fast and simple recovery operation by exploiting the characteristics of ring topology and also provides efficient resource utilization by using multiple backup paths per link to improve the sharability of overall spare resources in the networks. With this method, layered reliability can be provided to network services by enabling priority-based robustness against multiple failures. The performance results reveal the trade-off between the resource efficiency for single failure and the robustness for multiple failures, and show the preconfiguration of a few logical cycles per link can provide enhanced resource efficiency and priority-based hierarchical robustness.

Among recent trends in Quality of Service (QoS) provisioning in the Internet is the Differentiated Services Architecture, termed DiffServ. The successful deployment of Diffserv to provide a premium QoS guarantees to network traffic requires an effective admission control mechanism, which needs to be scalable and relatively simple to implement. In this paper we present a QoS network framework with novel and effective measurement-based resource management and admission control mechanisms. The mechanism is based on the characteristics of measured arrival and departure traffic. Those characteristics are captured via a passive monitoring. We implement the mechanism at the edge routers of a DiffServ Domain. The admission control mechanism is only executed at the edge routers and doesn't require any signaling between inner routers. The mechanism does not depend on the underlying network topology or any specifications of the cross traffic present in the domain. Therefore the mechanism is scalable. In addition, the proposed approach does not require any traffic policing mechanism at the entrance of the network. This approach can provide the statistical QoS guarantees to a variety of service classes within a DiffServ domain. We show that the proposed framework can provide a high degree of network resource sharing among multiple traffic classes while satisfying their QoS requirements. To evaluate the effectiveness of the proposed framework, we perform a set of simulations on a number of bursty video traffic sources.

In medical education, many of computerized Problem-Based Learning (PBL) systems are used into their training curricula. But these systems do not truly reflect the situations which practitioners may actually encounter in a real medical environment, and hence their effectiveness as learning tools is somewhat limited. Therefore, the present study analyzes the computerized PBL teaching case, and considers how a clinical teaching case can best be presented to the student. Specifically, this paper attempts to develop a web-based PBL system which emulates the real clinical situation by introducing the concept of a "time sequence" within each teaching case. The proposed system has been installed in the medical center of National Cheng Kung University in Taiwan for testing purposes. The participants in this study were 50 of 5th grade (equivalent to 1st grade students in a medical school of the American medical education system) students for the evaluation process. Some experiments are conducted to verify the advantages of designing teaching cases with the concept of the "time sequence."

Currently, space division multiplexing (SDM), where individual data streams are transmitted from different antennas simultaneously, is expected to be a promising technology for achieving a high data rate within a limited frequency band in a multiple-input multiple-output channel. In this paper, transmitter and receiver architectures of SDM applications are described, and performance improvement with the increase of data streams is shown referring to results of computer simulations. In addition, channel coded systems are also evaluated.

We implemented all-fiber delay line using linearly chirped fiber Bragg gratings (CFBG), which can be applicable for reflectometry or optical coherence tomography (OCT). Compared with the previously reported delay lines, the proposed fiber-based optical delay line has in principle novel advantages such as automatic dispersion cancellations without additional treatment and a gain in optical delay that is dependent on parameters of used CFBGs. Dispersion compensation in optical delay line (ODL), which is the indispensable problem in bulk optics based ODL, is demonstrated in fiber by using two identical but reversely ordered CFBGs. Amplified variable optical delay of around 2.5 mm can be obtained by applying small physical stretching of one of CFBGs in the proposed scheme. The operational principles of the all-fiber variable optical delay line, which are based on the distributed reflection characteristic of a CFBG employed, are described. Especially properties such as in-line automatic dispersion cancellation and amplified optical delay under strain are dealt. To demonstrate the properties of the proposed scheme, which is theoretical consequences under assumptions, an all-fiber optical delay line have been implemented using fiber optic components such as fiber couplers and fiber circulators. With the implanted ODL, the group delay and amplified optical delay length was measured with/without strain. The wavelength independent group delay measured within reflection bandwidth of the CFBG has proved the property of automatic dispersion cancellations in the proposed fiber delay line. Optical delay length of 2.5 mm was obtained when we apply small physical stretching to the CFBG by 100 µm and this is expressed by the amplification factor of 25. Amplification factor 25, which is less than theoretical value of 34 due to slipping of fiber in the fiber holder, shows that the proposed scheme can provide large optical delay with applying small physical stretching to the CFBG. We measure slide glass thickness to check the performance of the fiber delay line and the good agreement in measured and physical thickness of slide glass (1 mm thick) validates the potential of proposed delay line in the applications of optical reflectometry and OCT. We also discuss the problem and the solution to improve the performance.

In this letter, a new blind anti-jammer pre-processor is proposed for GPS receivers to alleviate performance degradation due to strong jammers. Since strong jammers have been successfully removed before despreading, the proposed scheme can effectively extract the signals-of-interest, leading to significant performance enhancement as compared with conventional methods.

A novel optical header extraction scheme based on optical differential phase shift keying--DPSK--decoding is examined analytically and experimentally. The header is applied in front of the payload, on the phase of a pulsed optical level introduced for the duration of the header. The proposed scheme offers maximized header extraction efficiency, required by the electronics to identify the header bits and control the switch. At the same time, the payload is transmitted at maximum extinction ratio. Analytical results prove the enhanced performance of the decoding scheme with respect to the extinction ratio and in comparison to other DPSK based schemes. Moreover, the utilised scheme is cost efficient and easily upgradeable to any bit rates and adds minimum complexity at the transmitter and detector parts of the system. Finally, the implementation of the developed technique in a real optical packet switch is demonstrated, where header extraction, reading, processing and switch control using field programmable gate array--FPGA--technology is successfully demonstrated.

This paper describes pixel-parallel image-matching circuit schemes that provide the optimal binarization, the high-speed low-power comparison, and the accurate matching of fingerprint images needed for fingerprint verification. Image binarizing is adjusted adaptively during the fingerprint sensing operation. The obtained image is compared with the template in the pixel array, and the results from all of the pixels are totaled by a variable-delay circuit at high speed and low power. For accurate matching, the image is scanned by shifting it in the pixel array while maintaining whole image. The experimental results demonstrate that the proposed schemes provide optimal binary images of most fingers under any condition and environment, 11-µs 147-µW totaling of results from 20,584 pixels, and wide-range image scanning and accurate matching for fingerprint images. These schemes are effective for fast and low-power fingerprint verification for a single-chip fingerprint sensor and identifier.

A new edge-coloring algorithm for bipartite graphs is presented. This algorithm, based on the framework of the O(m log d + (m/d) log (m/d) log d) algorithm by Makino-Takabatake-Fujishige and the O(m log m) one by Alon, finds an optimal edge-coloring of a bipartite graph with m edges and maximum degree d in O(m log d + (m/d) log (m/d)) time. This algorithm does not require elaborate data structures, which the best known O(m log d) algorithm due to Cole-Ost-Schirra depends on.

In this paper we give an algorithm to generates all series-parallel graphs with at most m edges. This algorithm generate each series-parallel graph in constant time on average.

In this paper, firstly, effects of third order dispersion (TOD) on coupled pulses are analyzed. Then, averaging method is modified and proved to be an effective way for obtaining non-radiative bi-soliton solution of the TOD perturbed nonlinear Schrodinger equation (NLSE), which models a dispersion managed (DM) optical transmission system. Finally, the obtained bi-soliton evolution behavior is studied, and compared with that of uni-soliton. With the increase of average TOD, pulse velocity of bi-soliton largely deviates from that of uni-soliton. Thus, even though TOD cannot be exactly vanished in fabrication, it is suggested to compensate average TOD as low as possible.

We have implemented a distributed sensor system based on an array of fiber Bragg gratings (FBGs), which can measure up to 1000 points with a single piece of fiber. The system consists of FBGs having the same resonant wavelengths and small reflectivities (0.1 dB), and a wavelength tunable optical time-domain reflectometer (OTDR). To interrogate the distributed grating sensors and to address the event locations simultaneously, we have utilized the tunable OTDR. A thermoelectric temperature controller was used to tune the emission wavelength of the OTDR. The operating temperature of the laser diode was changed. By tuning the pulse wavelength of the OTDR, we could identify the FBGs whose resonant wavelengths were under change within the operating wavelength range of the DFB LD. A novel sensor cable with dry core structure and tensile cable was fabricated to realize significant construction savings at an industrial field and in-door and out-door applications. For experiments, a sensor cable having 52 gratings with 10 m separations was fabricated. To prevent confusion with unexpected signals from the front-panel connector zone of the OTDR, a 1 km buffer cable was installed in front of the OTDR. The proposed system could distinguish and locate the gratings that were under temperature variation from 20 to 70.