A new optical path cross-connect system architecture (OPXC) based on delivery and coupling matrix switches is described. This OPXC provides the maximum compatibility for a wavelength path (WP) network and a virtual wavelength path (VWP) network. In other words, the proposed architecture easily evolves from WP-OPXC to VWP-OPXC. This salient feature can not been achieved with conventional OPXCs. Another attractive feature of this OPXC is its high modularity for OPXC capacity expansion.

A radial line slot antenna (RLSA) is a slotted waveguide planar array for the direct broadcast from satellite (DBS) subscriber antennas. A single-layered RLSA (SL-RLSA) is excited by a radially outward traveling wave. The antenna efficiency of more than 85% has already been realized. These antennas are designed on the assumption of perfectly rotationally symmetrical traveling wave excitation; the slot design is based upon the analysis of a slot pair on the rectangular waveguide model with periodic boundary walls. However, the slots perturb the inner field and the actual antenna operation is not perfectly symmetrical. This causes the efficiency reduction especially for very small size antenna. This paper presents a fundamental analysis of the inner field of the radial waveguide. It is impossible to analyze all the slot pairs in the aperture as it is and only the slots in the inner few turns are considered since these provide dominant perturbation. The calculated results are verified by the experiments and reasonable agreement is demonstrated. Some design policies are suggested for enhancing the rotational symmetry.

The sidelobe canceler in radar systems is a highly computational demanding problem. It can be efficiently tackled by resorting to the QR decomposition mapped onto a systolic array processor. The paper reports several mapping strategies by using massive parallel computers available on the market. MIMD as well as SIMD machines have been used, specifically MEIKO Computing Surface, nCUBE2, Connection Machine CM-200, and MasPar MP-1. The achieved data throughput values have been measured for a number of operational situations of practical interest.

Different signature codes in an optical code division multiple access (CDMA) network have been known to demonstrate different performances. The performance of different signature codes in an optical CDMA network was analyzed here in this paper by including the performance evaluation for the synchronization process which was not considered previously. Both auto- and cross-correlation properties of the signature codes were found to be important. In addition, the performance comparison of (n, w1, 1, 1), (n, w2, 2, 1) optical orthogonal codes (OOC's), and (n, w3, w3, 1) extended prime code demonstrated that an (n, w2, 2, 1) OOC could accommodate more users than the other two.

This paper describes the optical characteristics and static fatigue reliability of a zirconia alignment sleeve, which is a component part of an optical connector with zirconia ferrules. This combination of sleeve and ferrules hardly generates any wear debris during connector insertion and removal cycles. This has reduced the cleaning frequency of the ferrule endface during cycles and greatly improved the return loss stability of the optical connectors. The zirconia alignment sleeve enables stable return loss characteristics to be achieved over a wide temperature range as it has the same thermal expansion coefficient as the zirconia ferrule. Furthermore, the gauge retention force for the zirconia alignment sleeve is defined with a view to its practical use. This force must be between 2.0 and 3.9 N to allow stable optical connections to be made under various mechanical and environmental conditions. We also clarify the conditions for a proof test by which to prevent the occurrence of static fatigue fractures in the sleeve, and we confirm the validity of the test. The static fatigue parameters for zirconia ceramics and derived from the static fatigue theory for brittle materials and fracture testing. We use these static fatigue parameters to predict the lifetime of a zirconia sleeve under working stress. An appropriate stress level for the proof test which eliminates weak sleeves, is about 3 times greater than working stress. The strength of the sleeve as demonstrated in the proof test is confirmed by accelerative stress aging. The performance of this sleeve is superior to that of a conventional copper alloy sleeve and the proof test confirms its reliability; under 0.1 FIT for 20 years of use.

High-speed pulse propagation, up to several hundred Mbps or higher, will play an important role in telecommunication systems for B-ISDN. High-performance packaging, especially high-speed, high-throughput interconnection, is strongly required. For advanced telecommunication systems, giga-bit signal transmission has been developed at the multi-chip module level, and 300 to 600 Mbps signal transmission has been reached at the printed circuit board level. Electrical inter-cabinet interconnections of 150 to 300 Mbps have been achieved for up to several tens of meters. High-speed, high-throughput connectors are the key to achieving high-performance telecommunication packaging systems. Two technologies are extremely important. One is for high-density, high-pin-count connectors, and the other is for high-speed signal transmission connectors. The requirements for the connectors needed for advanced high-performance telecommunication systems are described. Several high-density, high-bandwidth connectors developed for high-performance packaging system are introduced.

A magneto-optical head lens actuator was developed for use at a high information bit rate and high density recording. A high bit rate at the outer diameter of a 300 mm disk (velocity = 27.3 m/s) was attained by mounting an aspherical plastic lens and optimizing the shape of lens holder for achieving higher spurious frequency over 30 kHz, utilizing the finite element method (FEM). Another approach was focused on reducing gain peak at the natural frequnecy by adopting "multi-wire" and a silicone "gel box" damping system for stabilizing the pull-in characteristic for focusing and tracking. By the actuator realization, a high density recording of 0.34 µm/bit and high information bit rate 80 Mbps (1, 7 code modulation) recording were attained.

This paper describes a trial coaxial surface mounted connector for PGA-type high-speed multichip modules (MCM). An MCM connector is needed to ensure testability and connection reliability of MCMs mounted on a printed circuit board. Our connector consists of a coaxial elements, a common ground housing made of conductive resin, and a ground contact spring plate. It has 68 signal contacts. We investigated the performance of this connector by experiment and simulation. Its insertion force is only about 53 gf per signal pin. The characteristic impedance is from 45.6 Ω to 61.4 Ω. The average resistance between two contacts is 28 mΩ with a deviation of less than plus or minus 5 mΩ. The insertion is -0.4 dB at 1.0 GHz. Crosstalk noise is less than 1.2%. This prototype connector can transmit pulses of up to 1.2 Gb/s, showing that it is applicable to high-speed MCMs.

This paper describes a newly developed 22 liquid crystal optical switch for 1.3µm single-mode fiber use. This switch state can be freely set at either the cross or the bar state. The measured performance of two prototype 22 liquid crystal optical switches is given. Tests confirm that the 3 values are a maximum insertion loss of 1.5dB, a crosstalk attenuation of more than 26.1dB, and a return loss of more than 28.9dB. Requirements for optical switches for fault isolation are theoretically clarified from a LAN system view point.

It is shown that for a class of interval matrices we can estimate the location of eigenvalues in a very simple way. This class is characterized by the property that eigenvalues of any real linear combination of member matrices are all real and thus includes symmetric interval matrices as a subclass. Upper and lower bounds for each eigenvalue of such a class of interval matrices are provided. This enables us to obtain Hurwitz stability conditions and Schur ones for the class of interval matrices and positive definiteness conditions for symmetric interval matrices.

A new self-holding optical switch that consists of an optical matrix board and a precision robot is proposed. Fabrication and evaluation of 33 optical matrix boards confirm the feasibility of large-size optical switching. Suppressing deviations in the groove position will realize lower loss optical matrix boards in the near future. The apparent roughness of the groove walls can be evaluated simply and effectively by measuring return loss with an interferometric optical-time-domain reflectometer.

In this paper, the relationship between contact materials and sticking characteristics, and stability of contact resistance to obtain excellent contacts for telecommunication relays, is studied. The contact switching current for telecommunication relay is low. Moreover, contact force and opening force in these relay are respectively several mN. Nine kinds of contact materials are selected as a experimental factor. They are Ag, Ag-Ni (Ni: 0.03 to 20%), Ag-Cu 10%, Ag-Pd 60% and Pd-Ru 10%, and are overlaid with gold except Pd-Ru 10%. In this study, contact life tests on a commercial ultra-miniature telecommunication relay by mounting above-mentioned contacts are conducted. The sticking and the contact resistance are monitored at each switching operation in the contact life test. After the life test, the contact surfaces are observed, and the depth of crater, the height of pip and projected concave area are measured, then the relationship between the sticking morphologies and the composition of each material are studied. As the result of this study, the contact sticking of telecommunication rely is assumed to be the result of mechanical locking, and the effects of the Ni content in the Ag-Ni contacts is clarified. Moreover, it is confirmed that the effects of opening force on the sticking characteristics are remarkable.

Recognizable series is a model of a sequential machine. A recognizable series S is represented by a triple (λ,µ,γ), called a linear representation of S, where λ is a row vector of dimension n specifying the initial state, γ is a column vector of dimension n specifying the output at a state, and µ is a morphism from input words to nn matrices specifying the state transition. The output for an input word w is defined as λ(µw) γ, called the coefficient of w in S, and written as (S,w). We present an algorithm which constructs a reduced linear representation of an unknown recognizable series S, with coefficients in a commutative field, using coefficient queries and equivalence queries. The answer to a coefficient query, with a word w, is the coefficient (S, w) of w in S. When one asks an equivalence query with a linear representation (λ,µ,γ), if (λ,µ,γ) is a linear representation of S, yes is returned, and otherwise a word c such that λ (µc) γ(S, c) and the coefficient (S, c) are returned: Such a word c is called a counterexample for the query. For each execution step of the algorithm, the execution time consumed from the initial step to the current step is O(mN 4M), where N is the dimension of a reduced linear representation of S, M is the maximum time consumed by a single fundamental operation (addition, subtraction, multiplication or division), and m is the maximum length of counterexamples as answers to equivalence queries returned until that step.

A technique for pulse code modulation (PCM) encoding using a T-Model neural network is described. Performance evaluation on both the T-Model and the Hopfield model neural-based PCM encoders is carried out with PSpice simulations. The PSpice simulations also show that the T-Model neural-based PCM encoder computes to a global minimum much more effectively and more quickly than the Hopfield one.

This paper describes a simple system of measuring the spatial distributions of spectral intensities with AgI-421 nm and AgI-546 nm among many optical spectrums emitted from an arc discharge between separating Ag contacts. In order to detect the intensities of two optical spectrums, the prototype equipment has two sets assembled with a CCD color linear image sensor, a lens and optical filters, which are arranged on rectangularity. The intensities of two spectrums can be recorded with 2 ms time-resolution within a long arc duration on a digital memory. The recorded digital signals are processed by using a personal computer in order to reconstruct two spatial distributions of spectral intensities in a cross section of arc column with the Algebraic Reconstruction Technique.

This paper describes a noise resistant algorithm for estimating 3-D rigid motion from optical flow. We first discuss the problem of constructing the objective function to be minimized. If a Gaussian distribution is assumed for the niose, it is well-known that the least-squares minimization becomes the maximum likelihood estimation. However, the use of this objective function makes the minimization procedure more expensive because the program has to go through all the points in the image at each iteration. We therefore introduce an objective function that provides unbiased estimators. Using this function reduces computational costs. Furthermore, since good approximations can be analytically obtained for the function, using them as an initial guess we can apply an iterative minimization method to the function, which is expected to be stable. The effectiveness of this method is demonstrated by computer simulation.

Electromechanical devices such as relays, switches, connectors and printed wiring boards have shown quick growth along with remarkable progress of electronic products in a recent few decades. For the present, outstanding tasks common to these devices are further downsizing, higher density and broading of bandwidth, on the assumption of keeping high performance and high reliability. These tasks are realized by part production improvement for higher precision and automatic assemblies, development of constituent materials and development of breakthrough structural technologies such as a surface mount technology and an active assembly ferrule technology in optical connectors and so on. In this paper, the technical trends as well as the motive technologies are overviewed for each device.

Creating a bandwidth abundant B-ISDN requires the further development of path technologies. Optical path cross-connect nodes (OXCs) will be required that offer very high levels of expandability. The present limited traffic demands must be efficiently supported while permitting easy step-wise expansion in capacity. This paper proposes two OXC architectures that offer high modularity with regard to incoming/outgoing links or the number of multiplexed wavelengths in each link. This paper briefly reviews, for optical path realization, the wavelength path (WP) and the virtual wavelength path (VWP) techniques. The proposed OXC architectures provide flexibility and minimum investment to encourage introduction but support incremental network growth and investment to match traffic demand. The architectures make it easy to upgrade a WP network to a VWP network, simply by replacing some optical components. It is also shown that the proposed OXC architectures ensure effective optical signal detection after a long-haul optical fiber transmission because they minimizes signal power losses within the OXC. Therefore, the proposed OXC architecture can be applied to global area networks. The proposed OXC architectures will play a key role in realizing the optical path infrastructure for the future bandwidth abundant B-ISDN.

Lexical-functional grammars (lfg's) were introduced to define the syntax of natural languages. In lfg's, a finite set of attribute-value pairs called an f-structure is associated with each internal node in a derivation tree. For efficient parsing, some subclasses of lfg's were proposed. However, these subclasses have been shown to generate at least one -complete language. In this paper, we introduce a subclass of lfg's called pd-lfg's. In pd-lfg's, an f-structure forms a pushdown stack. For a node v in a derivation tree and at most one specified child vi of v, the f-structure of vi is obtained by performing a specified pushdown stack operation on the f-structure of v. We prove the equivalence of the generative capacity of modified head grammars (mhg's) and that of pd-lfg's. Since the languages generated by mhg's are known to be recognizable in O(n6) time, the languages generated by pd-lfg's can be recognized in O(n6) time.

This paper presents a novel and successful optimization algorithm for optimizing Multiple-valued Logic (MVL) functions based on Petri net theory. Mathematical properties and Petri net modeling tools to implement MVL systems are introduced. On the basis of these properties and modeling tools, the optimization algorithm can synthesize, analyze and minimize an arbitrary quaternary logic function of n-input variables. The analysis technique of optimization algorithm is a well-established concept from both theories of MVL and Petri nets, and this can be applied to specify and optimize any MVL Petri net system. In this paper, Petri nets of Galois field have been proposed in order to form a complete system, which can be used to realize and construct VLSI circuit of any MVL function. Based on the Petri nets of Galois field and the proposed algorithm, the quaternary minimum and maximum functions have been analyzed, minimized, and designed. These applications have demonstrated the usefulness of optimization algorithm. Based on Petri net theory, the analysis revealed important information about MVL Petri net modeled systems, where this information has been used to evaluate the modeled system and suggest improvements or changes. For evaluation, advantages of the proposed method over a conventional logic minimization method are presented. Also, we have observed that the MVL Petri nets have the following advantages: Designers can exhibit clearly, simply and systematically any complex MVL Petri net nodel, number of concurrent operations is increased, number of places and transitions that are needed to realize a MVL model is very small, and the interconnection problems can be greatly reduced.