Steganography is a technique that conceals the very existence of communication by means of hiding secret messages in innocuous cover objects. We previously developed a steganographic method that uses standard MIDI files (SMFs) as cover objects. Our method could conceal the secret messages in SMFs without changing their sound. We also investigated the effectiveness of our method against steganalysis. This steganalytic research revealed that files embedded using our method are vulnerable to detection, because stego SMFs lose the imprints borne by sequencers. In this study, we describe two improved methods of steganography that enable even stego SMFs to keep the sequencer's imprint. As a result, we improved the resistance of SMFs against steganalysis but there was a slight reduction in the embedding rate.

The new hybrid antenna structures having external high-impedance-plane (HIP) shield are proposed. These antennas consist of normal patch or dipole antenna, working as a radiator, and HIP shield working as a reflector. The external HIP shield helps to reduce the undesired backward radiation. Generally, metal shield should be placed a quarter wavelengths apart from the antenna, but HIP shield can be placed close to the antenna and low profile structure can be obtained. In addition, compared with single-layer HIP antennas, having a patch surrounded by HIP structure, these hybrid antennas have the advantage of installation because the shielding effect can be obtained by attaching the external shield under the existing antenna. We fabricated HIP boards and combined with a microstrip patch or a regular dipole. The hybrid patch antenna with HIP shield improves the front-to-back radiation ratio (F/B ratio) similar to the single-layer HIP antenna or the hybrid patch with metal shield. But the dipole antenna with HIP shield, the F/B ratio is worse than the dipole with metal shield. These results indicate the TM mode antenna is suitable for the HIP shield in terms of the F/B ratio improvement.

In this paper, a joint adaptive interference canceller (AIC) and maximum likelihood (ML) decoder scheme is proposed for a space-time coded DS-CDMA system with the difference between arrival times from transmit antennas. As the arrival time difference causes not only ISI and MAI, but also inter-antenna interference, performance degradation in the space-time coded DS-CDMA system is more severe than that of a regular DS-CDMA system with single transmit antenna. To mitigate the effect of the interference during space-time decoding, a joint algorithm for the proposed scheme merges adaptation process of the AIC into a ML decoding algorithm. Performance of the proposed scheme is evaluated for QPSK space-time trellis codes with two transmit antennas. It is shown that the proposed scheme achieves better performance than the conventional ML decoding scheme.

This paper proposes a technique for indexing, clustering and retrieving images based on their edge features. In this technique, images are decomposed into several frequency bands using the Haar wavelet transform. From the one-level decomposition sub-bands an edge image is formed. Next, the higher order auto-correlation function is applied on the edge image to extract the edge features. These higher order autocorrelation features are normalized to generate a compact feature vector, which is invariant to shift, image size. We used direction cosine as measure of distance not to be influenced by difference of each image's luminance. Then, these feature vectors are clustered by a self-organizing map (SOM) based on their edge feature similarity. The performed experiments show higher precision and recall of this technique than traditional ways in clustering and retrieving images in a large image database environment.

An adaptive backstepping and high order sliding modes control algorithm is proposed for output tracking of mobile robots. The controller can greatly reduce the chattering due to conventional sliding modes technique. The proposed algorithm has certain robustness with respect to the external random disturbances and good adaptability with respect to the parametric uncertainty. The effectiveness of the proposed control strategy is demonstrated by simulations studies.

Future electric lights will be comprised of white LEDs (Light Emitting Diodes). White LEDs with a high power output are expected to serve in the next generation of lamps. In this paper, an indoor visible data transmission system utilizing white LED lights is proposed. In the proposed system, these devices are used not only for illuminating rooms but also for an optical wireless communication system. This system is suitable for private networks such as consumer communication networks. However, it remains necessary to investigate the properties of white LEDs when they are used as optical transmitters. Based on numerical analyses and computer simulations, it was confirmed that the proposed system could be used for indoor optical transmission.

In this paper a digital frequency domain RFI (Radio Frequency Interference) cancellation scheme for DMT (Discrete Multitone) based VDSL (Very high speed Digital Subscriber Line) systems is presented. The proposed algorithm has been optimized and characterized in terms of complexity and performance. Optimizations were also performed from an implementation point of view by deducing key dependencies among our RFI model coefficients that let us drastically reduce the size of the memories involved. System simulations showed the effectiveness of the canceller: in terms of VDSL performance parameters such as bit rate, the optimized cancellation scheme recovers almost totally the performance degradation due to RFI.

In this paper we describe the investigation of design methodology of a planar duplexer consisting of BPFs using mixed tapped resonators. Firstly, we propose the planar duplexer consisting of bandpass filters (BPFs) using a tapped open-ended λ/2 resonator and a tapped λ/4 resonator. The duplexer is designed based on the general filter theory with narrow band approximation and tap-coupling technique. The actual duplexer is fabricated using a coplanar waveguide (CPW). Secondly, downsizing of the planar duplexer is carried out based on the BPF using stepped impedance resonators (SIRs). Lastly, another type of duplexer consisting of different BPFs using mixed tapped resonators is investigated in the same manner. The results of this study lead us to the conclusion that the design methodology is useful for realizing the high-performance planar duplexer fabricated without increasing the number of elements.

The first implementations of X-band AlGaN/GaN HEMT single-ended frequency doublers are presented in this paper. Two types of fundamental frequency signal reflector schemes have been demonstrated for the frequency doubler application. Open-circuited quarter-wavelength microstrip line at the fundamental frequency is utilized for the reflector in a conventional way. In the other architecture a printed antenna is employed as a radiator as well as a novel fundamental frequency reflector. A microstrip rectangular patch antenna operating at the second harmonic frequency of the doubler was designed and integrated with AlGaN/GaN HEMT based on active integrated antenna design concept. Using AlGaN/GaN HEMT with 1 mm gate periphery, two 4 to 8 GHz frequency doublers were designed by the described design methodologies, fabricated, and tested. For the conventional frequency doubler, a conversion gain of 0.6 dB and with an output power of 15 dBm was observed. A conversion gain of 5 dB and an output power of 25 dBm with embedded antenna gain were achieved at a drain voltage of 12 V for the doubler integrated with the patch antenna.

Integration of the IP/MPLS network and the WDM optical mesh network is a promising approach to realizing an efficient backbone network. Because of the great volumes of traffic carried, the social cost incurred by a failure will be extremely high, so survivability is very important in the backbone network. In survivable IP/MPLS over WDM backbone networks, cooperation of the optical level fault recovery and the IP/MPLS level fault recovery is essential. This paper analyzes cost characteristics of the optical level fault recovery and the IP/MPLS level fault recovery. A mathematical programming method is proposed to minimize the initial network cost when the IP/MPLS level fault recovery is utilized in the survivable IP/MPLS over WDM networks. Using this method, the initial network cost needed for the IP/MPLS level fault recovery is compared with that for the optical level fault recovery. The initial network cost for the LSP (Label Switched Path) protection scheme is smaller than that for the shared light-path protection scheme and larger than that for the pre-plan type light-path restoration scheme. The LSP protection scheme is suitable for the best-effort type traffic while the shared light-path protection scheme may be suitable for the bandwidth guaranteed type traffic.

In this paper, we propose a scalable Extended Differentiated-Services (EDS) architecture to guarantee edge-to-edge explicit rate allocation. In presence of flows with explicit rate allocation, to share bandwidth fairly, a new fairness definition is proposed. Based on EDS and the proposed fairness definition, a scalable fair Edge-to-Edge Congestion Control Algorithm with Explicit Rate Allocation (ECC-ERA) is presented to solve the bandwidth assurance problem facing Differentiated Service architecture, where EDS uses congestion control packets to carry the flow-related states and congestion control information. By designing efficiency control and fairness control separately, the ECC-ERA can achieve good scalability to link capacity, round-trip time and number of flows. It will be shown that EDS plus ECC-ERA outperforms the general Diff-Serv bandwidth guarantee approaches. The main advantages of EDS+ECC-ERA are as follows: (1) it not only can guarantee explicit rate allocation, but also can guarantee near-zero packet loss in core routers, high utilization, lower and smoother queueing delay, better fairness and better protection from unresponsive traffic. (2) Neither resource pre-reservation nor sophisticated scheduling mechanisms are required. The simple FIFO at core routers is enough. (3) EDS plus EC-ERA is very efficient and can be used as end-to-end QoS building block.

The forbidden state problem is to synthesize a control policy for preventing a Petri net from reaching any state in its forbidden set. In this paper, we address a liveness preserving version of the forbidden state problem for lossy Petri nets. During the process of keeping Petri nets out of the set of their forbidden states, a control policy does not disable a live marking. We present a method to solve the above problem based on fixed point computations. We show that for lossy Petri nets, the problem is decidable. From a practical viewpoint, the problem associated with our fixed point approach is 'state explosion. ' In order to overcome this problem, we propose a symbolic approach, which uses Boolean functions for implicitly representing the set of states. We use Boolean functions for representing reachable markings. Thus OBDDs, compact representations of Boolean functions, can reduce the time and space involved in solving the forbidden state problem described in this paper.

Immune system protects living body from an extraordinarily large variety of bacteria, viruses, and other pathogenic organisms. Based on immunological principles, new computational techniques are being developed, aiming not only at a better understanding of the system, but also at solving engineering problems. Our overall goal for this paper is twofold: to understand the real immune system from the information processing perspective, and to use idea generated from the immune system to construct new engineering application. As one example of the latter, we propose an artificial immune system architecture inspired by the human immune system and apply it to pattern recognition. We test the proposed architecture by the simulations on arbitrary sequences of analog input pattern classification and binary input pattern recognition. The simulation results illustrate that the proposed architecture is effective at clustering arbitrary sequences of analog input patterns into stable categories and it can produce stronger noise immunity than the binary network .

A clustering scheme for ad hoc networks is aimed at managing a number of mobile devices by utilizing hierarchical structure of the networks. In order to construct and maintain an effective hierarchical structure in ad hoc networks where mobile devices may move at high mobility, the following requirements must be satisfied. (1) The role of each mobile device for the hierarchical structure is adaptive to dynamic change of the topology of the ad hoc networks. The role of each mobile device should thus change autonomously based on local information in each mobile device. (2) The overhead for management of the hierarchical structure is small. The number of mobile devices in each cluster should thus be almost equivalent. This paper proposes an adaptive multihop clustering scheme for highly mobile ad hoc networks. The results obtained by extensive simulation experiments show that the proposed scheme does not depend on mobility and node degree of mobile devices in the network, which satisfy the above requirements.

A "rooted" plane triangulation is a plane triangulation with one designated vertex r and one designated edge incident to r on the outer face. In this paper we give a simple algorithm to generate all connected rooted plane triangulations with at most m edges. The algorithm uses O(m) space and generates such triangulations in O(1) time per triangulation without duplications. The algorithm does not output entire triangulations but the difference from the previous triangulation. By modifying the algorithm we can generate all connected (non-rooted) plane triangulations with at most m edges in O(m3) time per triangulation.

An optical FM system using an optical FM LD (laser diode) and an optical frequency discriminator (OFD), in which a nonlinear compensation scheme based on the interaction between its nonlinearities can minimize intermodulation distortion. This paper theoretically investigates the minimization influence for 3rd plus 5th order intermodulation distortion power for an optical FM radio-on-fiber system. The carrier to noise-plus-distortion power ratio (CNDR) is theoretically analyzed in employing the OFD whose transmission characteristic is controlled by a phase shifter. The results show that the designed receiver can achieve higher CNDR in the application of multicarrier transmission.

The dense wavelength division multiplexing (DWDM) technique is very attractive for effectively increasing the channel capability, even for access networks. Some DWDM radio-on-fiber (ROF) systems have been studied recently. In those systems, fiber Bragg gratings (FBG) or arrayed waveguide gratings (AWG) were used to demultiplex DWDM ROF signals. In this report, an alternative channel-selection scheme of DWDM millimeter-wave-band ROF signals by optical heterodyne detection with dual-mode local light is newly proposed. Error-free demultiplexing and transmission over a 25-km-long SMF of the DWDM signal, which consists of two 60-GHz-band, 155-Mb/s-DPSK ROF signals, are demonstrated.

A new technique for optical generation of high-purity millimeter-wave (mm-wave) signals--namely, by synthesizing the outputs from cascadingly phase-locked multiple semiconductor lasers--was developed. Firstly, a high-spectral-purity mm-wave signal was optically generated by heterodyning the outputs from two phase-locked external-cavity semiconductor lasers. The beat signal was detected by a p-i-n photodiode whose output was directly coupled to a coax-waveguide converter followed by a W-band harmonic mixer. By constructing an optical phase-locked loop (OPLL), a high-spectral-purity mm-wave signal with an electrical power of 2.3 µW was successfully generated at 110 GHz with an rms phase fluctuation of 57 mrad. Secondly, the frequency of the mm-wave signal was extended by use of three cascadingly phase-locked semiconductor lasers. This technique uses a semiconductor optical amplifier (SOA) to generate four-wave-mixing (FWM) signals as well as to amplify the input signals. When the three lasers were appropriately tuned, two pairs of FWM signals were nearly degenerated. By phase-locking the offset frequency in one of the nearly degenerated pairs, the frequency separations among the three lasers were kept at a ratio of 1:2. Thus, we successfully generated high-purity millimeter-wave optical-beat signals at frequencies at 330.566 GHz with an rms phase fluctuation of 0.38 rad. A detailed analysis of the phase fluctuations was carried out on the basis of measured power spectral densities. The possibility of extending the mm-wave frequency up to 1 THz by using four cascadingly phase-locked lasers was also discussed.

A novel RF CMOS high Q-value active inductor is proposed in this work by using simple cascode RC feedback compensation technique. The performance of this active inductor has maximum Q-value about 1.2E6, inductance value from 3.5 nH to 4.5 nH and 3E-5Ω of minimum total equivalent loss, in the range of 1.2 GHz to 2 GHz.

One of the most basic characteristics of the image is accompanied by its blur. It was 1962 that I had discovered for the first time in the world that the blur was a Gaussian type. In this paper the outline is described about historical details concerning this circumstances.