bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionization Equilibrium and Equation of State of Hydrogen Plasmas in Strong Magnetic Fields
Authors: Potekhin A. Y. , Chabrier G. , Shibanov Yu. A. , Ventura J.
Published: July 2007

We study hydrogen plasmas at magnetic fields B ∼ 1012 – 1013 G, densities pH ∼ 10−3 – 103 g cm−3 and temperatures T ∼ 105.5 –106.5 K, typical of photospheres of middle‐aged cooling neutron stars. We construct an analytical free energy model of the partially ionized plasma, including into consideration the decentred atomic states, which arise due to the thermal motion across the strong field. We show that these states, neglected in previous studies, may contribute appreciably into thermodynamics of the outer atmospheric layers at pH ≲ 1 g cm−3 and typical B and T. We take into account Coulomb non‐ideality of the ionized component of the plasma affected by intense magnetic field. Ionization degree, occupancies and equation of state are calculated, and their dependences on the temperature, density and magnetic field are studied.
Remarks on Luttinger's Derivation of Kubo's Conductivity Formula
Authors: Lee M. H.
Published: July 2007

Luttinger has given a derivation of Kubo's static conductivity formula in a famous paper some thirty years ago. In a subsequent analysis to obtain the Einstein relation, he introduced an assumption. We show that this assumption is not consistent with linear response theory, on the basis of which the conductivity formula is derived. This inconsistency can be removed. At the same time, one can extend Luttinger's treatment to include the dynamic conductivity. This generalization is allowed by the recurrence relations method, which solves the Heisenberg equation of motion formally as well as explicitly.
Characterization of the State of Hydrogen at High Temperature and Density
Authors: Militzer B. , Magro W. , Ceperley D.
Published: July 2007

Fermionic path integral Monte Carlo simulations have been applied to study the equilibrium properties of the hydrogen and deuterium in the density and temperature range of 1.6 < r3 < 14.0 and 5000K < T < 167000K. We use this technique to determine the phase diagram by identifying the the plasma, the molecular, atomic and metallic regime. We explain how one can identify the phases in the path integral formalism and discuss the state of hydrogen for 5 points in the temperature‐density plane. Further we will provide arguments for the nature of the transitions between the regimes.
Diagnostics of a Chemically Active, Pulsed Microwave Plasma for Deposition of Quartz‐like Films
Authors: Brockhaus A. , Behle St. , Georg A. , Schwabedissen A. , Soll Ch. , Engemann J.
Published: July 2007

A remote microwave plasma has been used for the deposition of scratch‐resistant quartz‐like films. Process gases are argon, oxygen, and hexamethyl‐disiloxane. Input power is modulated and the effects on the plasma as well as on the deposition process are studied by means of various diagnostic methods. The film deposition rate is slightly reduced under most conditions but film quality (i.e., cluster size, roughness, scratch resistance) may be improved. A precursor has been identified by mass spectrometric measurements. Its relation to volatile oxides is discussed. The atomic oxygen density and the electron density are determined temporally‐resolved. By a suitable choice of the pulse frequency the time‐averaged densities of both species can be significantly enhanced as compared to the continuous case. Consideration of the plasma power balance explains how electron density and temperature are influenced by pulsing. It is concluded that the optimum pulse frequency has to be matched to the electron loss rate which mainly depends on the geometrical dimensions of the process chamber.
Architecture for delivery of broadband services to the residence
Authors: Coathup L. , Goddard G. W. , McEachern J. , Bears J.
Published: July 2007

This paper presents a technology and architecture perspective on the cost of evolving today's copper access network, optimized for POTS, to a fibre access network providing both narrowband and broadband services. Architectures are assessed using application studies based on cost models for actual routes in North America. This study identifies three architectures as serious candidates (i.e. close to copper in cost) for providing POTS service in 1992: the double star, the active pedestal and the star‐bus.

The active pedestal and the star‐bus architectures were similar in first costs and were the least expensive, costing between 5 and 15 per cent more than the copper reference depending on the number of subscribers subtending a given optical fibre. The double star is 20 per cent more expensive than the copper reference.

All three architectures are potentially attractive for broadband service upgrade depending on the bandwidth required per subscriber. The star‐bus is most bandwidth sensitive. Moderate video bandwidths, nominally 150 Mb/s/subscriber, favour the active pedestal architecture. Conversely, service environments requiring much greater than 150 Mb/s/subscriber favour the double star architecture.
The realization of integrated services in a digital distributed star local network
Authors: Brady Jon D.
Published: July 2007

The BIDS system will go on trial in early 1990 and it will be a unique system for combining broadband, telephony and data services. The present design uses analogue and digital transmission techniques, but a design for a completely digital system may be required. A study of future requirements had to be undertaken to ensure that the system would adequately serve the customer of the year 2000 and onwards. A design for a digital secondary link is presented employing a modular optical dual‐wavelength diplex system.
A fiber‐optic system for deployment of pots and CATV services in the FRG
Authors: Romans Claude , Large David
Published: July 2007

An optical system architecture intended to provide subscriber access for future network sevices must also support existing services at a cost equivalent to copper. An integrated optical‐fiber system which meets this criterion and provides both CATV and telephone service has been designed under contract to the Deutsche Bundespost and is planned for pilot installation early in 1990 in Köln, Federal Republic of Germany.

A bus network was chosen for implementation of the trial system because of the advantages it provides over a point‐to‐point star network. Economies result from using much less fiber per subscriber, and from the sharing of optical transmitter and receiver costs among many subscribers.

The telephony portion of the system initially provides existing telephone service based on digital transmission technology yet is configured to support the development of new services. The CATV portion of the network is designed to be functionally equivalent to the coaxial system now being deployed, but offers advantages in reliability and future expansion possibilities.

The implementation of a system using a bus architecture to provide network access for telephone and broadband CATV services over optical fiber cables is described.
A star‐configured fiber‐to‐the‐curb system
Authors: Menendez R. C. , Vogel M. O.
Published: July 2007

Fiber‐to‐the‐curb (FTTC) system proposals have arisen because of the present high cost of fiber‐to‐the‐home (FTTH) systems. With FTTC systems, fiber is brought only as far as the service access point (SAP). From there, copper drops carry signals from the SAP to several residences. Owing to the extensive sharing of optical sources and the fibers running to the SAP, the per‐subscriber system cost is greatly reduced relative to the per‐subscriber cost of a FTTH system. In addition, elimination of the optical network unit (ONU) at the home may offer new options for powering and battery back‐up.

This paper presents an analysis of a star‐configured, fiber‐to‐the‐curb distribution network that serves up to ninety‐six customers, initially providing two plain old telephone service (POTS) channels to each customer. Three system variations, serving either four, six, or eight customers per SAP, are examined. We also estimate the installed first costs (IFC) of the distribution link (remote node to customer) for the three FTTC scenarios and compare them to the IFC of a FTTH system with similar capabilities. Star‐configured FTTC architectures can be installed for substantially less ($1180‐$825/customer for four to eight customers per SAP) than the estimated $2920 per subscriber cost associated with FTTH systems. Finally, we propose an upgrade strategy, consistent with the passive photonic loop (PPL) network, to support future high bandwidth services.
Priority cell discarding for overload control in BISDN/ATM networks: An analysis framework
Authors: Petr David W. , Frost Victor S.
Published: July 2007

The broadband integrated services digital networks (BISDNs) of the future will use asynchronous transfer mode (ATM) for switching and transport of basic transport units called cells. These networks are likely to exhibit extremely bursty traffic characteristics which could cause significant queue overload conditions. This paper suggests that priority cell discarding, in which a delivery priority (also known as a loss priority) is assigned to each cell, is a viable alternative for controlling this overload. We also present a framework for the analysis and comparison of the performance of such priority discarding systems. The framework consists of a general analysis model appropriate for BISDNs using ATM, a two‐dimensional structural classification of priority discarding algorithms and suggestions for performance measures, one of which is a generalization of the often‐used throughput measure. We illustrate how this framework can be useful in systems analysis by introducing a specific discarding optimization problem.
Fibre optics in cable television
Authors: Chiddix James A.
Published: July 2007

An invited contribution from a member of the editorial board, or another respected figure in the profession, in which a particular viewpoint is put forward giving an informed, but not necessarily conventional, opinion on a major topic in the field of communication systems.
New microwave and fibre‐optic supertrunking system configurations
Authors: Straus T. M. , Hsu R. T. , Kaufman L. A.
Published: July 2007

Rapidly changing fibre‐optic and AML microwave technologies have opened up a new range of possibilities in implementing CATV supertrunks. These considerations apply not only to new builds, but also to many existing AML microwave systems whose reach could be extended. The same technologies can be applied to improve system reliability either through redundancy configurations or by dividing overly long microwave paths into smaller segments. Combinations of the two technologies are explored. System performance improvements possible with higher power transmitters and on‐frequency repeaters are delineated. Advantages of configurations employing fibre to AML, AML to fibre, ‘low power’ channelized AML with high power microwave repeaters, and fibre in parallel with AML are set forth.
Standardization of a multi‐configuration medium access protocol for broadband ISDN
Authors: Woloszynski Charles H.
Published: July 2007

This paper examines the current work within various standards bodies to define a multi‐configuration medium access control (MAC) protocol for operation between broadband ISDN terminals. To begin, the configurations in which the MAC protocol is expected to operate are introduced. The relation between the MAC protocol and the broadband ISDN resource allocation schemes is then discussed. Several MAC protocol proposals currently being discussed in various standards bodies, each with unique assumptions regarding resource allocation in broadband ISDN, are then described and compared. Finally, areas for future work on this topic are identified.
Queueing behaviour of two interconnected buffers of a packet network with application to the evaluation of packet routeing policies
Authors: Stavrakakis Ioannis
Published: July 2007

In this paper, the behaviour of two interconnected nodes of a packet communication network is analysed. The packet arrival process to the first node is described by an i.i.d. discrete time process. The packet arrival process to the second node consists of two mutually independent streams; one stream carries the packet output process from node 1; the other stream carries a packet traffic described by a dependent discrete time process. For this system, the following quantities are derived: (a) the first two moments of the buffer occupancy and the mean packet delay in the first node; (b) a description of the packet output process of the first node; (c) the first two moments of the buffer occupancy and the mean packet delay in the second node.

In the sequel, the behaviour of the buffers is investigated under some simple routeing policies in node 1. The objective at this point is to evaluate the queueing behaviour of both buffers under some routeing policies and it is not to seek for the optimal packet routeing policy in the first node. It is shown how the routeing policy in node 1 can be incorporated in the description of the packet output process of node 1 and, then, the behaviour of buffer 2 be accurately evaluated.

The numerical results show that the queueing behaviour of buffer 2 cannot be accurately evaluated by incorporating a Bernoulli approximation on the output process of node 1. Furthermore, it is shown that different routeing policies in the first node result in different intensities of the queueing problems in the second node, although the packet output rate from the first node is constant for all routeing policies considered. It turns out that a routeing policy which best randomizes the packet output process results in the least significant queueing problems in the second node. The latter implies that routeing decisions should be based not only on the desired packet traffic rates (which achieve optimality in the load distribution among the nodes), but also on the packet randomization affect of the routeing policy considered.
Analysis of the self‐framing performance of mBnB line codes
Authors: Fair I. J. , Krzymien W. A.
Published: July 2007

This paper introduces a method to analyse the self‐framing properties of mBnB line codes. Consideration of correlation in the received bit stream yields a three step analysis technique: (1) evaluation of the probability that any n‐bit sequence in the received bit stream simulates a codeword, (2) development of a mathematical description of the desired lock entry and lock exit algorithms, and (3) the derivation and evaluation of equations which give framing performance for the frame search strategy of interest. Following discussion of the analysis technique, the framing performance of a 7B8B code is investigated. The results of the analysis are compared with those obtained by simulation to confirm the validity of the analysis technique.
Hierarchical NTSC compatible HDTV system architecture — A North American perspective
Authors: Toth Arpad G. , Tsinberg Mikhail , Rhodes Charles W.
Published: July 2007

High definition television (HDTV) has become a major world‐wide event in the television arena. Since the early 1980s, when HDTV was first demonstrated by Japan, a number of alternative systems have emerged. These systems clearly reflect the business and political objectives of the particular countries or organizations. In North America, which is the largest single consumer market in the world, technical, business and political considerations are shaping the evolution of HDTV.

This paper describes a possible advanced television (ATV) architecture for North America and defines its functional modules and corresponding interfaces. The developed model is recommended as a design tool for standardizing ATV in North America and analysing interrelationships of the functional modules on the economic basis. The paper proposes an ‘hierarchical’ ATV emission system with full NTSC compatibility and HDTV quality. Solutions are recommended for terrestrial broadcast, CATV and satellite. This work describes a total systems approach to HDTV called HDS‐NA (high definition system for North America). The two emission signals of HDS‐NA: HDMAC‐60 and HDNTSC are characterized. RF alternatives for the terrestrial broadcast of HDTV are also discussed.
A broadband switching experiment
Authors: Briley B. E. , Tokar J. V.
Published: July 2007

A broadband switching experiment was presented at the ISS'87 and Telecom'87 conferences in Phoenix, Arizona, and Geneva, Switzerland, respectively and at the March 1988 Fair in Hanover, West Germany. This experiment was significant in that it illustrated techniques for switching broadband signals with a wide range of frequencies, formats and ultimate purposes. In particular, simultaneous switching (within the same switch fabric) of 30 MHz PFM, 45 Mb/s PCM, and 140 Mb/s PCM was demonstrated. These signals carried full‐motion, full‐colour NTSC video for desk‐to‐desk video teleconferencing, off‐the‐air broadcast video programming, and surveillance camera video. They also carried RGB video, digitized stored video images, and computer‐computer communications. Software features afforded a friendly human interface, allowing multiple, flexible service capabilities. Further, the experimental system, when deployed in Phoenix, demonstrated control of its capabilities via a narrowband ISDN link to an optically remoted 5ESS® switch module one km distant, which homed on a 5ESS host switch about 32 km further away. The technologies employed in the switch and the surrounding equipment are detailed, and the significance of this experiment relative to the broadband ISDN (BISDN) thinking is discussed.
A broadband central office for ATM
Authors: De Prycker M. , Bauwens J.
Published: July 2007

Recently, a growing interest has been shown towards fast packet switching, ATD (asynchronous time division), or the more general term ATM (asynchronous transfer mode) in a number of companies and organizations such as CCITT and RACE. In Belgium a broadband experiment is planned using this technique. This paper focuses its attention on the central office (switching exchange).

This exchange is a multistage network constructed with independent switching elements based on the self‐routing principle. The load control in the exchange is provided by a static load control mechanism applied to the logical connections granted on these links. Simulation results show that this load control mechanism can work perfectly if used in the proper environment.
World‐wide standardization of broadband ISDN
Authors: Byrne W. R. , Papanicolaou A. , Ransom M. N.
Published: July 2007

A growing market demand for high‐performance voice, data, image and video networks, coupled with advances in high‐speed technologies has heightened interest in broadband ISDN (BISDN) throughout the world. Network providers, equipment manufacturers and standards bodies are working jointly to accelerate the definition of BISDN interfaces in anticipation of emerging market opportunities. BISDN is being designed as the foundation upon which to implement very flexible, high‐bandwidth, high‐performance networks. A multiplexing concept called asynchronous transfer mode (ATM), which can offer bandwidth on demand at rates exceeding 150 Mb/s, high‐speed packet switching, and an efficient protocol which adapts existing information streams into the ATM format are key attributes of the emerging BISDN network standards. This paper reviews the motivations behind BISDN, explains its key attributes and challenges and discusses possible strategies for evolving today's network toward BISDN.
Experimentation on asynchronous switching techniques for broadband ISDN
Authors: Melen R. , Giorcelli S. , Garetti E. , Demichelis C. , Perardi F.
Published: July 2007

This paper deals with a proposed implementation exploiting the new asynchronous transfer mode (ATM) multiplexing and switching techniques. In particular, the basic architectural and functional choices are outlined and various aspects are examined regarding the implementation of a switching arrangement using ATM switching techniques, giving some indication about its hardware and software architecture and the foreseeable system performance.
An ATM self‐routeing switch architecture
Authors: Imagawa Hitoshi , Urushidani Shigeo , Hagishima Koichi
Published: July 2007

This paper describes a new ATM self‐routeing switch architecture for integrated voice, video and data communications. The proposed switch consists of multi‐stage circulated shift registers and output buffers and uses the difference between incoming and outgoing line numbers as a routeing header. Every cell with a routeing header is easily, routed to its destination line with no contention in the switch. Point‐to‐multipoint connections can also be provided without additional complicated hardware. The routeing algorithm, switching mechanism and applications of the proposed switch are discussed.
Integrated BISDN access connection
Authors: Nilsson Gunnar , Westin Tommy
Published: July 2007

The broadband ISDN (BISDN) or integrated broadband communication (IBC) customer access connection (CAC) must meet a wide variety of technical and economic requirements in order to be competitive with dedicated network accesses and cope with the evolution of future services. Many proposals for broadband implementations are based on various service scenarios. Such scenarios may very well be applicable to certain user categories or at certain points in time. The CAC to be defined, however, has not to be based ononesuch scenario–but has to be able efficiently to support all the varying and evolving customer needs during a long period of time. In this paper the requirements are analysed and a CAC system concept fulfilling the basic requirements is put forward bearing in mind the interaction with relevant basic technology. A step‐by‐step evolution scenario for the BISDN/IBC network with emphasis on the CAC system introduction is outlined and finally some standardization issues are highlighted.
Fibre backbone for cable TV using multi‐channel am video trunking
Authors: Chiddix James A.
Published: July 2007

This paper updates a scenario for the evolutionary integration of optical fibre transmission technology into existing cable television networks first presented in 1988. The resulting ‘fibre backbone’ yields a hybrid fibre/coaxial network with significantly better reliability and transmission quality than present systems. System and electro‐optical component advances in the last year are reviewed, and the merits of various modulation techniques are examined. The fibre backbone approach emphasizes continuing the broadband delivery of a large number of video signals to the consumer.
Multiservice CATV—from the viewpoint of the IBCN
Authors: Stefler S.
Published: July 2007

In countries where basic telecommunication services cannot satisfy all demands, as in Hungary and some other countries, the function of CATV may be different from that in the developed countries. While maintaining the primary, program distribution function it is expedient to use the cable TV as a local, autonomous data network too. From this viewpoint the up‐to‐date CATV network is a forerunner of the integrated broadband communication networks (IBCNs). Surveying these possibilities, and their economical implementation, is in the interest of many telecommunications administrations. The Research Institute of the Hungarian PTT (the PKI) has for some time been dealing with the multi‐purpose application possibilities of cable TV systems too. In the framework of this research work, PKI has recently established an experimental cable TV network which is suitable for examining other functions as well.
Remarks on standard fibre‐optic LANs
Authors: Beale N. C. L.
Published: July 2007

This paper explains the importance of standard fibre‐optic LANs, and gives an overview of the state of development of the main emerging fibre‐optic LAN standards. Fibre‐optic enhancements to 802·3, 802·4 and 802·5 are discussed, as well as FDDI and FDDI‐2. A brief mention is made of 802·6 and SONET, which are not LANs but are relevant to the discussion. The need for a rational cabling infrastructure is mentioned, as is the need for conformance tests. Some of the practical reasons why it makes sense to have fibre available at the end stations are discussed.
QAM and QPRS digital broadband cable systems
Authors: Sreenath K. , Feher Kamilo , Sasase Iwao
Published: July 2007

The performance of high‐level modulation schemes in non‐linear broadband digital communication systems is investigated. The tolerance of 16‐, 64‐, 256‐QAM and 49‐, 225‐QPRS schemes to these non‐linearities is given in terms of their phase margins. Our research results show that high level QAM schemes are less sensitive to non‐linearities when operated in offset mode. Comparison of non‐linearly amplified broadband QAM and QPRS schemes reveals that QPRS schemes need less carrier‐to‐noise ratio (CNR) than corresponding QAM schemes for identical operating conditions. Also, when the non‐linearities are not severe, the degradation in performance is controlled by AM/PM characteristic of the broadband amplifier.
A BISDN customer access architecture optimized in relation to network implementation technology
Authors: Trondoli Alberto , Vago Gian Angelo
Published: July 2007

This paper aims at identifying an architecture model for a fibre‐optic‐based customer access network optimized at the minimum cost for the implementation technology and passive components inserted between the distribution centre and the subscriber premises. The optimization has been carried out on the basis of technical and economic considerations by taking into account the technology and market trends foreseen in this field. Moreover, a prediction of the cost reduction trend in the short‐and medium‐term scenario (up to 1995) has been derived for both the various passive components and the overall network implementation costs.
ATM switches—basic architectures and their performance
Authors: Rathgeb Erwin P. , Theimer Thomas H. , Huber Manfred N.
Published: July 2007

The prospect of a broadband ISDN based on the ATM principle has stimulated the development of new, high‐performance switching node architectures. In this paper different options for the switching networks used in such a node will be discussed in some detail. First, some generic architectures for the individual switching elements will be presented including the aspects of buffering and collision resolution, followed by a short classification of different types of switching networks and some performance figures for delta networks, a class of multi‐stage, single‐path interconnection networks. In the last section, the sensitivity of the performance results with respect to the traffic assumptions will be discussed.
A multistage ATM switch with interstage buffers
Authors: Kim Hyong Sok , Leon‐Garcia Alberto
Published: July 2007

Asynchronous transfer mode (ATM) is the transport technique for the broadband ISDN recommended by CCITT (I.121). Many switches have been proposed to accommodate the ATM that requires fast packet switching capability.1‐8 The proposed switches for the broadband ISDN can be classified as being of input queueing or output queueing type. Those of the input queueing type have a throughput performance which is approximately 58 per cent that of the output queueing type. However, output queueing networks require larger amounts of hardware than input queueing networks. In this paper, we propose a new multistage switch with internal buffering that approaches a maximum throughput of 100 per cent as the buffering is increased. The switch is capable of broadcasting and self‐routeing. It consists of two switching planes which consist of packet processors, 2 x 2 switching elements, distributors and buffers located between stages and in the output ports. The internal data rate of the proposed switch is the same as that of the arriving information stream. In this sense, the switch does not require speed‐up. The switch has log2 N stages that forward packets in a store‐and‐forward fashion, thus incurring a latency of log2 N time periods. Performance analysis shows that the additional delay is small.
A three‐stage architecture for very large packet switches
Authors: Liew Soung C. , Lu Kevin W.
Published: July 2007

This paper proposes a three‐stage broadband packet switch architecture with more than 16,000 ports for a future central office. The switch is constructed by interconnecting many independent switch modules of small size which can be implemented using modifications of various well‐studied switch fabric designs. Channel grouping is used to provide multiple paths for each input‐output pair in order to decrease delay and increase throughput. We show that, for a given size, switch modules with channel grouping are simpler to realize than those without channel grouping. A datagram packet routeing approach is adopted in order to avoid table look‐up that would be required by virtual‐circuit routeing. Ways of preserving the sequence integrity of packets under this situation are presented. Performance analyses show that a 32,768 x 32,768 switch with acceptable performance can be constructed based on switch fabrics of no more than 128 ports.
Development of murine hepatic sinusoidal endothelial cells characterized by the expression of hyaluronan receptors
Authors: Nonaka Hidenori , Tanaka Minoru , Suzuki Kaori , Miyajima Atsushi
Published: July 2007

Endothelial cells (ECs) display distinct structural and functional characteristics depending on the tissue and developmental stage; however, the development of tissue‐specific ECs remains poorly understood. Here, we describe the development of hepatic sinusoids in mice based on the expression of hyaluronan receptors Stab2 and Lyve‐1. Flk‐1+ cells in and around the liver bud begin to express Stab2 at embryonic day (E) 9.5, before the formation of vascular lumen. Hepatic sinusoidal endothelial cells (HSECs) begin to express Lyve‐1 at E10.5, and both markers continue to be expressed in HSECs thereafter. Although HSECs and lymphatic ECs (LECs) are known to share functional and phenotypic characteristics, we clearly show that HSECs can be distinguished from LECs by the expression of molecular markers and higher endocytotic activity. Our results provide new insight into the development of tissue‐specific ECs and phenotypic criteria to distinguish HSECs from other types of ECs, including LECs. Developmental Dynamics 236:2258–2267, 2007. © 2007 Wiley‐Liss, Inc.
Analysis and synthesis of continuous‐time hysteretic neural networks
Authors: Jin'no Kenya , Saito Toshimichi
Published: July 2007

In this article the authors propose a continuous‐time neural network which includes bipolar hysteretic elements. They then consider the problem of synthesis in order to satisfy the following conditions: I) the system has no oscillating solutions; II) any desired patterns are stored as stable output vectors; and III) the total number of false stable output vectors is made as small as possible. The authors then prove a sufficient condition for I) and the necessary and sufficient conditions for II). Based on these results, they propose a synthesis procedure which is also effective for III). The domain of attraction of stable outputs may be easily calculated using a fast algorithm using exact solutions. The efficiency of the procedure is confirmed through experimental results.
Several properties of permissive feedbacks in petri nets with external input places
Authors: Takai Shigemasa , Kodama Shinzo , Ushio Toshimitsu
Published: July 2007

This paper considers the controlled discrete event systems modeled by Petri nets with external input places. A maximal element in the set of permissive feedbacks is called a maximally permissive feedback. First, a simpler condition is derived for its unique existence which does not require constructing the set of permissive feedbacks.

Next, a necessary and sufficient condition is derived for the reachable set under the unique maximally permissive feedback to be equal to the set of markings which satisfy the given predicate. Moreover, synthesis of the unique maximally permissive feedback is demonstrated for a simple manufacturing system.
II‐cascade wave digital filters that have zero sensitivity at each matching point and realize arbitrary transfer functions
Authors: Ishiwata Shunichi , Nishihara Akinori , Fujii Nobuo
Published: July 2007

The circuit with zero sensitivity at the matching points is desirable in the sense that a very low sensitivity can be expected in the passband. It should also be noted that the wave digital filter (WDF) with a II‐cascade structure has the advantage that the sensitivity in the stopband is lower than WDF with a T‐cascade structure. However, the synthesis method has not been known for WDF with a II‐cascade structure with the zero amplitude sensitivity at the matching points which can realize an arbitrary transfer function. This paper is an attempt to realize such a WDF.

First, it is shown what type of sections should be used as the reference section of a doubly resistor‐terminated reactance filter. The two terminating resistances are set equal to avoid the situation where the sensitivity at the matching point turns out to be nonzero because of the effect of the terminating resistance ratio. Then the replacement of the multiplier is shown so that the forementioned state is maintained, even if the multiplier coefficients are quantized.

It is shown that WDF exists corresponding to each section, where the forementioned replacement can be applied and the structural boundedness is retained even after the coefficients are quantized. As a result, it is shown that WDF actually exists with a II‐cascade structure with the zero amplitude sensitivity at the matching points which can realize an arbitrary transfer function.
Relation between generalized radial basis function (GRBF) networks and neural networks
Authors: Miyazaki Akio , Yamada Tsuyoshi
Published: July 2007

The problem of learning an input‐output mapping from a given set of samples can be handled by applying the theory of approximation, e.g., the spline approximation and regularization. It is well known that by formulating this kind of learning problem based on the regularization theory, generalized radial basis function (GRBF) networks are derived.

The GRBF network has a three‐layered structure (input layer–intermediate layer–output layer). This suggests that the network is related closely to the multilayer neural network.

This paper discusses the relation between the GRBF network and the neural network, and it is shown that the three‐layered neural network can be derived approximately from the GRBF network using the projection transform and the inverse projection transform. Based on this result, a construction method for the neural network is presented and the method is applied to the pattern class discrimination problem.
Effect of generation method of modulated‐noise reference signal on speech quality evaluation
Authors: Ogawa Mineyoshi , Irii Hiroshi
Published: July 2007

This paper discusses the modulated‐noise reference unit (MNRU), which is used to represent quantitatively the effect of the quantization distortion due to voice coding on the voice quality. The noise generation method, which has only implicitly been discussed, is formulated; and the effect of various generation parameters on the voice quality evaluation is examined. The following results are obtained. The noise source has a uniform amplitude distribution which simplifies the digital processing compared to the generation of noise with a Gaussian distribution. The effect on the quality is small even if the noise‐generation cycle is short. The simplified method proposed by Bellcore Co., U.S.A., is examined for comparison. It is shown through an international evaluation experiment that there is no significant difference in the result of quality measurement even if the simplified generation method is adopted.
Decomposition algorithms for live and safe free choice nets
Authors: Nishimura Tadaaki , Lee Dong‐Ik , Kodama Shinzo , Kumagai Sadatoshi
Published: July 2007

The free‐choice net is a subclass of the Petri net. It is a class which can explicitly represent both the essential concurrency and the nondeterministic aspects of the concurrent system. the class can be considered as an extension of the state machine where concurrency is included. It can also be considered as an extension of the marked graph where the nondeterministic aspect is included. There have been a number of studies on the free choice net with the dynamic constraint that it should be live and safe (LSFC). This LSFC net has a structural feature: it can be decomposed into a set of strongly connected state machines (called S components). If the minimal set of S components (S decomposition set) covering the given LSFC net can be efficiently determined, it will be possible to derive powerful methods in the analysis and performance evaluation of the parallel system. This paper discusses the polynomial‐order algorithm that determines the S‐decomposition set for the LSFC net.
Parallel adaptive infinite impulse response digital filters using Kalman filters
Authors: Cao Jianting , Yahagi Takashi , Lu Jianming
Published: July 2007

This paper presents a new design method for parallel adaptive infinite impulse response (112) digital filters using Kalman filters in the time domain. the parallel Kalman filter (PKF) and the improved parallel Kalman filter (IPKF) based on the divided estimation of an unknown system's impulse response are extended to parallel adaptive IIR digital filters. the finite impulse response (FIR) digital filters can be replaced by reduced order IIR digital filters. This is particularly useful when high‐order FIR digital filters are necessary. A method is presented that ensures the stability of IIR digital filters with little extra computational effort.
Reliability evaluations of microprocessor system with watchdog timer
Authors: Yasui Kazumi , Nakagawa Toshio , Harata Yoshihisa
Published: July 2007

A watchdog timer has been used in many practical fields as a simple method of monitoring the behavior of a microprocessor. However, it is impossible at present to detect any errors that occur in a microprocessor using a watchdog timer. It would be necessary to develop a watchdog timer with more advanced capabilities and to improve the reliability of the entire system, including a microprocessor. This paper considers a microprocessor which has a watchdog timer with self‐checking. Assuming that a microprocessor and a watchdog timer fail mutually independently, we formulate the following stochastic model: when errors of a microprocessor have occurred, a watchdog timer detects them with a certain probability and resets a microprocessor to an initial state. Otherwise, a microprocessor goes to a fault state. We derive reliability measures such as mean operating times and cost effectiveness until the fault of a microprocessor is reached. Further, we evaluate how much more reliable the system with a watchdog timer becomes.
Solution of nonlinear vision problem based on forward and approximated inverse optics models
Authors: Hayakawa Hideki , Wada Yasuhiro , Kawato Mitsuo
Published: July 2007

A solution of the nonlinear vision problem based on forward and approximated inverse optics models is proposed. In the solution, the geometrical structure modification in the three‐dimensional (3‐D) world required due to the 2‐D brightness error is separated from that required due to the smoothness constraint. Therefore, a simple and fast algorithm for each modification can be used.

First, the optimality of the converged solution in the algorithm and the convergence of the algorithm is proved. In the proof, an optimal solution of the linear optimization problem is used for the approximated inverse optics. Next, the proposed algorithm is applied to the shape‐from‐shading problem. In the problem, a Newton‐like method is used that quickly gives the approximated optimal solution of the linear optimization problem. In computer simulations, it is demonstrated that the proposed algorithm can estimate the shape of an object within a small number of iterations in comparison with the Ikeuchi‐Horn algorithm.
An algorithm for making a correspondence of zero‐crossing points in a wavelet transform domain with second‐order derivative property
Authors: Watanabe Shinji , Saito Takahiro , Cheong Chakeon , Aizawa Kiyoharu
Published: July 2007

The multiscale wavelet transform (MWT) is the method of multiple resolution analysis using the wavelet transform. In MWT with the property of the second‐order derivative, the position of the zero‐crossing point of the transform signal corresponds to the position of the edge of the original signal. the edge has an important role in image information. If the correspondence of the zero‐crossing points related to the edges can be established between scanning lines or between frames by some means, the correspondence can be utilized in the sophistication of image processing (such as motion analysis, stereo matching, interpolation, and noise reduction). From such a viewpoint, this paper discusses the correspondence between the zero‐crossing points in MWT, i.e., the correspondence of scales and the correspondence between two similar signals, and presents a method that provides visually plausible correspondence as a result. Especially for the correspondence between signals, the accuracy of the correspondence of zero‐crossing points is improved by introducing the cost function. Computational complexity is kept within a practical range, by applying the dynamic programming and utilizing the branch structure of the zero‐crossing points among various scales. the idea of cross‐validation is applied to the correspondence of signals between the scanning lines of the image, and a method is composed that evaluates visually the quality of the signal correspondence method by the naked‐eye observation of this image. With this evaluation method, the usefulness of the proposed algorithm for the signal correspondence and its problems are indicated. It is shown that a visually reasonable result is obtained by adjusting the weight coefficient of the multiplication factor of the cost function in the signal correspondence process.
Design of digital allpass functions with specified phase tolerances
Authors: Zhang Xi , Iwakura Hiroshi
Published: July 2007

In this paper, a new method is introduced for designing IIR digital allpass functions with specified phase tolerances. Since the phase error characteristics subject to the desired phase response have been specified in the interest bands, the phase design of digital allpass functions in the form of a linear programming problem can be formulated by using the Remez exchange algorithm. Then the linear equations are solved to obtain a set of filter coefficients and the optimal coefficients in the Chebyshev sense can easily be obtained through a few iterations. By appropriately selecting the initial extremal frequencies, the proposed design algorithm always converges, and the phase error characteristics can be arbitrarily specified. Finally, some design examples are presented to demonstrate the effectiveness of the proposed method.
Transform coding of images based on fractal functional set
Authors: Ogawa Hidenori , Nakagawa Masahiro
Published: July 2007

Orthogonal fractal basis functional sets are proposed for the compression of images with long‐tail power distributions. These functional sets are generated by the method of midpoint displacements from deterministic theory and are orthogonalized by the method of Schmidt. From computer simulations of transform data compression coding that uses a transform based on these functional sets and a nonuniform quantizer, the functional sets proposed in this paper are shown to better preserve the self‐similarity of fractal image data when compared to conventional methods that use the discrete cosine function (DCF). Also, for standard images that possess local and approximate self‐similarity fractal characteristics, although the measured SNR performance is lower, the proposed functional sets are shown to provide excellent subjective performance and to preserve the fractal properties of the images. On the other hand, for standard images that do not possess these fractal properties, compression errors are apparent in blocks from both smooth and edge regions of the images.
An estimation of acoustic parameters of piezoelectric telephone by Monte Carlo method
Authors: Kajikawa Yoshinobu , Nomura Yasuo , Ohga Juro
Published: July 2007

A problem in the telephone handset is that there is no design formula that can relate the values of the parameters in the acoustic equivalent circuit (acoustic parameters) of the earphone system directly to the shape (dimensions) of the actual handset. As a result, the design of the handset has been made very difficult. to derive such a formula, the values of the acoustic parameters must be estimated accurately from the actual measurement of the handset.

Previously, the authors have estimated that acoustic parameters, using the nonlinear optimizatoin technique, but a problem is still left that the number of parameters that can be simultaneously estimated is limited. This paper tries to solve this problem and proposes and estimation technique using the Monte Carlo method, which can also realize a high estimation accuracy. In the proposed method, an allowable range for the actual response is defined and the acoustic parameters are estimated by modifying the upper and the lower limits of each acoustic parameter so that the response stays within the allowable range.

The proposed method has the advantages that the number of parameters to be estimated is not limited, a good agreement can be realized with the actual response, and the decision can be made without intuition. the approach also provides a useful means for the design of the whole system. Although this paper discusses the estimation for the piezoelectric telephone handset, the proposed method can be applied effectively to any type of telephone handset.
An equivalent model for subband adaptive system and analysis of its performance
Authors: Ono Yoshihiro , Nishikawa Kiyoshi , Kiya Hitoshi
Published: July 2007

It is well known that the subband adaptive system is useful; however, the study of the theoretical analysis of the system does not seem sufficient. the theoretical analysis is problematic because of the structural constraint in which the input to the unknown system is not the same as the input to the adaptive filter. This paper attempts theoretical analysis of the subband adaptive system and proposes a new equivalent model that removes the foregoing constraint. Then the theory of the Wiener filter is applied to the equivalent model. the optimal ADF coefficient and the least‐mean‐square error (LMSE) in the subband adaptive system are theoretically derived. Lastly, the derived theoretical value is compared to the results of the experiment and the effectiveness of the proposed model and the theoretical expression are demonstated.
Acceptance and generation of general wave by a natural observation filter
Authors: Iijima Taizo
Published: July 2007

During the past few years, there has been a series of papers published on the theory of the natural observation method. As one of the important applications of this theory, the problems of acceptance and generation of a general waveform are discussed here. The case of polynomial waveforms and its corresponding theory was published previously. A great extension of that theory which covers general waveforms is presented here and its full picture is clarified.