Wavelength division multiplexed (WDM) routed optical networks represent the direction towards future high-capacity wide-area network applications. A serious issue in WDM-routed networks, though, is light-path allocation which requires a combination of optical routing and wavelength assignment. While near-optimal-routing and wavelength-assignment algorithms aimed at minimizing network wavelength requirements have been reported, the practicability of wavelength-routed optical networks depends on the number of wavelengths required to satisfy a given traffic demand. In this paper, we proposed two symmetrical routing and wavelength-assignment methods for optical networks with a Grid or ShuffleNet physical topology. Here, we consider the case of non-adaptive wavelength routing systems, where the operations performed in nodes are independent of the network traffic load. In this case, the routing differs somewhat from that in adaptive routing networks where the routing function may produce different results at different times. The path followed by a wavelength never changes in non-adaptive wavelength-routing networks. When all N(N-1) node-pairs are to be connected, our methods lower the wavelength requirement to (or close to) its calculated minimum. Symmetry is a basic feature of both these regular topologies, but there are differences in the features within the topologies. Our goal has been to try to make use of the symmetry, and the differences in the native symmetry features, of these regular topologies to yield a lower wavelength requirement.

The main objective of vehicle suspensions is to improve ride comfort and road holding ability. Though passive suspensions consist of spring and damper, active suspensions adopt an actuator in addition to passive suspensions. In this paper, a quarter car model with an asymmetric hydraulic actuator is used. Moreover, the damping coefficient of the damper, which is changed according to the actuator velocity, is considered. The LPV (Linear Parameter Varying) model is obtained by applying feedback linearization technique. Next, a gain-scheduled controller, based on LQ regulator with different weighting factor, is designed according to the actuator velocity and the stability of the proposed controller is also proved. The effectiveness of the proposed controller is shown by numerical simulations.

We describe the width conversion of an optical signal by using an erbium-doped fiber and an asymmetric optical circuit. The width of an optical signal was measured to be a respective 350 nsec and 200 nsec for a 70 m and 40 m fiber (Lf). The width of the pumping pulse was 5 nsec and the length of erbium-doped fiber was 3 m. We also extended the optical signals to a respective 300 nsec and 150 nsec wide at a pumping pulse 10 nsec by inserting a 60 m and a 30 m fiber (Lf) inside a circuit.

Two planar asymmetric coupled waveguides were fabricated by using different materials (InGaAsP and TiO2/Si) and tested as dispersion compensators (or pulse compressors). Compression of a more-than-10-ps chirped pulse is experimentally demonstrated by using an InGaAsP planar asymmetric coupled waveguide whose group velocity dispersion (GVD) is enhanced by structural optimization and is spectrally tuned to an input pulse as precisely as possible. A large polarization dependence of the pulse compression was also observed and indicates that the observed pulse compression results from dispersion compensation due to the GVD associated with supermodes. A new planar, asymmetric coupled waveguide with a large difference in refractive indices of the two waveguides was fabricated by using a combination of dielectric (TiO2) and semiconductor (Si) materials in order to obtain better GVD characteristics than semiconductor (for example, InGaAsP) asymmetric coupled waveguides. A preliminary experiment on pulse compression using the TiO2/Si planar asymmetric coupled waveguide was conducted. A 2.8-ps blue chirped pulse was compressed down to about 1 ps by a 1-mm-long waveguide (compression ratio: 0.375, which is better than those of the previous InGaAsP planar asymmetric coupled waveguides). This compression ratio agrees well with a theoretical result obtained by a numerical model based on a supermode's GVD.

LiNbO3 optical modulators for band-operation with a resonant modulating electrode are investigated in this paper. We propose an asymmetric resonant structure consisting of two arms of modulating electrodes, where one arm is open-ended and the other arm is short-ended. The voltage standingwave was enhanced by the resonance of the electrodes, so that effective optical modulation was achieved, while the length of the modulating electrode was much shorter than the conventional travelingwave-type electrodes. The optical response at 6.2 GHz of a resonant modulator designed by maximizing the normalized induced phase was 4.94 of the response at dc with a non-resonant modulator.

A power combining technique using a Fabry-Perot resonator with many more active devices is investigated. The Fabry-Perot power combiner consists of two mirrors with a circular groove mounted with the active devices. The power combiner has an axially symmetrical structure and operates at an axially symmetrical TEM01n mode so that uniform device-field coupling required for perfect power combining can be realized. By numerical calculation using the boundary element method, it was shown that high combining efficiency can be obtained when the active devices are mounted in the circular groove of larger radius on either of the two mirrors. In experiments at X-band, power combining efficiency over 90% was obtained for the case of twelve devices on either of the mirrors and the output powers of the twenty or twenty-four devices on both the mirrors were almost perfectly combined.

Large-scale effects of locally interacting agents are called emergent properties of the system. Emergent properties are often surprising because they can be hard to anticipate the full consequences of even simple forms of interaction. In this paper we address the following questions: how do heterogeneous agents generate emergent coordination, and how do they manage and self-organize macroscopic orders from bottom up without any central authority? These questions will depend crucially on how they interact and adapt their behavior. Agents myopically evolve their behavior based on the threshold rules, which are obtained as the functions of the collective behavior and their idiosyncratic utilities. We obtain the micro-macro dynamics that relate the aggregate behavior with the underlying individual behavior. We show agents' rational behavior combined with the behavior of others produce stable macro behavior, and sometimes unanticipated cyclic behavior. We also consider the roles of conformists and nonconformists to manage emergent macro behavior. As a specific example, we address an emergent and evolutionary approach for designing the efficient network routings.

A completely symmetric dual-level spiral inductor structure is proposed. The symmetry, area efficiency, the size dependence of the coupling factor, and the quality factors of the dual-level inductors are evaluated and compared with that of the single-level. This work demonstrates that, with most RF applications, the dual-level inductors are the better choice than the single-level.

The inter-cell interference between uplinks and downlinks in CDMA packet communication systems, employing a shared-TDD scheme, is evaluated under cellular environments. It is found that interference between base stations rarely degrades uplink throughput, but interference between mobile stations substantially degrades downlink throughput. A transmission power control scheme is proposed to improve the downlink throughput. The proposed scheme increases the transmission power of downlink packets when they are re-transmitted, and thus, improves the signal-to-interference ratio of the downlink re-transmission packets. Computer simulation shows that this scheme increases downlink throughput without sacrificing the uplink throughput until the uplink throughput reaches a maximum value.

By the growth of the Internet, the client's access to the Internet have been increasing. In order to meet those demands, asymmetric networks have become a great attraction. However, asymmetric networks composed of satellite and terrestrial links have not been enough investigated. Therefore, this paper proposes a new formula for TCP performance evaluation for the asymmetric networks. Using this evaluation formula, we calculate the throughput of TCP Reno over the asymmetric networks taking Slow Start into account. The calculation results are compared with the following: (1) the value based on an existing theoretical formula, (2) the outputs of simulation by NS (Network Simulator), and (3) the experimental results using VSAT (Very Small Aperture Terminal) satellite communication system for satellite links and the Internet for terrestrial links. As a result, it is shown that the new formula is more precise than the one already proposed.

This is a study on a certain group theoretic property of the set of encryption functions of a block cipher. We have shown how to construct a subset which has this property in a given symmetric group by a computer algebra software GAP4.2 (Groups, Algorithms, and Programming, Version 4.2). These observations on group structures of block ciphers suggest us that we may be able to set a trapdoor based on meet-in-the-middle attack on block ciphers.

The performance of a twisted-pair channel under ADSL environment is assumed to be dominated by far end crosstalk (FEXT) and additive white Gaussian noise (AWGN). In this paper, we study the channel capacity of the copper twisted pair and the optimum input power spectral density distribution at this channel capacity in the presence of ADSL environment. The channel capacity under different loop length and different input power will also be given. The simulation results show that the distribution of the optimum input power spectral density in the presence of AWGN and FEXT is not uniform. This is different from the situation where AWGN is the only interference, where the input power distribution is approximately uniform.

A novel residue arithmetic algorithm using radix-2 signed-digit (SD) number representation is presented. By this representation, memoryless residue arithmetic circuits using SD adders can be implemented. Conventional residue arithmetic circuits have been designed using binary number arithmetic system, but the carry propagation arises which limits the speed of arithmetic operations in residue modules. In this paper, a p-digit radix-2 SD number system is introduced to simplify the residue operation. For a modulus m, 2p-1 m 2p+2p-1-1, in a residue number system (RNS), the modulo m addition is performed by using two p-digit SD adders, one for the addition and one for the residue operation. Thus, the modulo m addition time is independent of the word length of operands. When m=2p or m= 2p 1, the modulo m addition is implemented by using only one SD adder. Moreover, a modulo m multiplier is constructed using a binary modulo m SD adder tree, and the modulo m multiplication can be performed in a time proportional to log 2 p. The VHDL implementation method for the presented algorithm is also discussed. The design and simulation results of some residue arithmetic circuits show that high speed residue arithmetic circuits can be obtained by the presented algorithms.

This paper presents the bit error rate (BER) upper bounds for trellis coded asymmetric 8PSK (TC-A8PSK) system using the Ka-band satellite in the rain fading environment. The probability density function (PDF) for the rain fading random variable can be theoretically derived by assuming that the rain attenuation can be approximated to a log-normal distribution and the rain fading parameters are calculated by using the rain precipitation data from the Crane global model. Furthermore, we analyze the BER upper bounds of TC-A8PSK system according to the number of states in the trellis diagram and the availability of channel state information (CSI). In the past, Divsalar and Simon has analyzed the BER upper bounds of 2-state TCM system in Rician fading channels; however, this paper is the first to analyze the BER upper bounds of TCM system in the rain fading channels. Finally, we summarize the dominant six factors which are closely related to the BER upper bounds of TC-A8PSK satellite system in the rain fading channel as follows: (1) frequency band, (2) rain intensity, (3) elevation angle, (4) bit energy to noise ratio, (5) asymmetric angle, and (6) availability of CSI.

The applications of reactance-loaded beam tilting dipole antennas have been reported by many researchers. The reactance elements loaded on the applications reported up to date have been used only for the purpose of beam tilting. This paper presents the basic characteristics of the beam tilting dipole antenna element in which one reactance element is used for the impedance matching at the feed point. The radiation pattern is tilted by the properly determined driving point position, and the loading reactance is used to obtain forced resonance without great changes in tilt angle. The numerical results demonstrate that the reactance element should be loaded in the region where the driving point is placed to obtain forced resonance of the antenna with little changes in beam tilt angle. In case the proposed forced resonant beam tilting antenna with 0.8λ length is driven at 0.2λ from the center, the main beam tilt angle of 57.7 degrees, the highest power gain of 8.6 dB, and VSWR=2.2 are obtained.

In order to guarantee pairwise independence of codewords in an ensemble of convolutional codes it is necessary to consider time-varying codes. However, Seguin has shown that the pairwise independence property is not strictly necessary when applying the random coding argument and on this basis he derives a new random coding bound for rate 1/n fixed convolutional codes. In this paper we show that a similar random coding bound can be obtained for rate k/n fixed convolutional codes.

This paper presents the several bifurcation phenomena generated in nonlinear three-phase circuit with symmetry. The circuit consists of delta-connected nonlinear inductors, capacitors and three-phase symmetrical voltage sources. Particular attention is paid to the subharmonic oscillations of order 1/2. We analyze the bifurcations of the oscillations from both theoretical and experimental points. As a tool of analysis, we use the homotopy method. Additionally, by comparing with single-phase and single-phase-like circuits, the special feature of the three-phase circuit is revealed.

If a four-port network is terminated by arbitrary impedances, the conventional methods for even- and/or odd-mode excitation analyses are not available because no symmetry planes exist. Under these conditions, two types of new design equations for asymmetric 3-dB branch-line hybrids are reported. To make sure that the derived design equations are correct and adaptable, simulations were performed under assumed ideal conditions for one type of asymmetric 3-dB branch-line hybrid and a uniplanar branch-line hybrid terminated by 50 Ω, 41.6 Ω, 55.6 Ω and 62.5 Ω was fabricated and measured for another type of asymmetric 3-dB branch-line hybrid.

The conductor-backed asymmetrical coplanar waveguide or micro-coplanar strip (MCS) line has been analyzed. The conformal mapping method is used to calculate the quasi-static effective permittivity εeff and characteristic impedance Z0. The computed results of the present work are found to be in good agreement when compared with the results obtained using the method reported by Yamashita et al. [1] and experimental values reported in [2]. A novel MCS end-coupled half-wavelength long resonator filter is designed to illustrate an application of the present work. The designed filter has 4% bandwidth at a center frequency of 10.5 GHz. The measured insertion loss is approximately 3.4 dB. One of the main advantages of the MCS filter compared to the CPW filter is that bond wires do not have to be used to maintain both coplanar ground at the same potential. The MCS filter is also easily integrable with other planar components and does not require a complicated transition to microstrip.

We propose an H-plane manifold-type triplexer with closely arranged junctions. Broadband characteristics for each bands are obtained by arranging filters closely near the end of the common waveguide. Three fundamental and sufficient parameters are introduced for numerical optimizations to determine the configuration of the broadband triplexer. The configuration including closely arranged junctions requires an generalized scattering matrix (GS matrix) of an asymmetric cross junction to simulate and design. We expand the mode matching technique (MMT) to be able to analyze this kind of discontinuities by joining two asymmetric steps discontinuities to a symmetric cross junction. This is suitable expressions for numerical calculations. The characteristics of the whole triplexer are obtained by cascading GS matrices of the corresponding discontinuities. The experimental results of the fabricated triplexer were compared with the simulated data, and the results agree well with the simulated one. The characteristics of the fabricated triplexer satisfy the request of the broad band operation and high power-handling capability.