bluuebunny/crossref_metadata_2025 huggingface dataset:
ChemInform Abstract: Raman Spectroscopic Studies of Metal‐Metal Halide Molten Mixtures: The Mercury‐Mercury(II) Halide Systems.
Authors: VOYIATZIS G. A. , PAPATHEODOROU G. N.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Cervical cancer screening and management practices among providers in the National Breast and Cervical Cancer Early Detection Program (NBCCEDP)
Authors: Saraiya Mona , Irwin Kathleen L. , Carlin Linda , Chen Xiao , Jain Nidhi , Benard Vicki , Montano Daniel E.
Published: July 2007

BACKGROUND.

This study was conducted to describe clinicians serving women in the National Breast and Cervical Cancer Early Detection Program (NBCCEDP) with regard to demographic and practice characteristics and their usual practices in cervical cancer screening and abnormal cytology management, as well as human papillomavirus (HPV) test use.

METHODS.

The authors analyzed data from a nationally representative survey conducted in 2004 of providers practicing 7 specialties that commonly offer cervical cancer screening. The program providers were compared with nonprogram providers.

RESULTS.

Program providers were found to be significantly more likely than nonprogram providers to be midlevel providers and to serve low‐income, racial/ethnic minorities who are insured by Medicaid. In addition, they had significantly more patients with abnormal Papanicolaou tests and were more likely to offer onsite colposcopy (57% vs 40%). Program providers were less likely to use liquid‐based cytology (LBC) as their sole method for cytology. Approximately 20% of program and nonprogram providers used HPV DNA testing as an adjunct to screening cytology and two‐thirds used HPV tests to manage patients with abnormal cytology results. However, many also used HPV testing for reasons not approved by the U.S. Food and Drug Administration (FDA), such as for screening women age <30 years.

CONCLUSIONS.

As of mid‐2004, program providers served racially and ethnically diverse, low‐income patients who are at high risk for cervical cancer compared with nonprogram providers, as intended by this program. Because many providers offered on‐site colposcopy, used LBC, and used HPV tests for patients with abnormal cytology results, they are well equipped to reduce the risk of cervical cancer. Many program providers used the HPV test for reasons that were not approved of by the FDA or reimbursed by the NBCCEDP. The results of this survey have informed training materials for program providers, reimbursement policies for LBC and HPV tests, and interventions to discourage inappropriate HPV testing. (See editorial on pages 000–000, this issue.) Cancer 2007. Published 2007 by the American Cancer Society.
Parallel computation on multilayer cluster grids
Authors: Zarrelli R. , Petrone M.
Published: July 2007

Cluster architectures are increasingly used to solve high‐performance computing applications. To build more computational power, sets of clusters, interconnected by high‐speed networks, can be used in an elaboration to form a cluster grid. In this type of architecture, it is difficult to exploit all the internal resources of a cluster, because each one can be shielded by a firewall and is usually configured with machines where there is only one visible IP front‐end node that hides all its internal nodes from the external world. The exploitation of resources is even more complicated if we consider the general case where each internal node of a cluster can be a front‐end node of an another cluster. This type of architecture has been defined as a multilayer cluster grid. In this paper, a Parallel Virtual Machine (PVM) extension is presented which, through a middleware solution based on the H2O distributed metacomputing framework, permits the building of a parallel virtual machine in a multilayer cluster grid environment. In addition, the existing code written for PVM can be executed into this environment without modifications. Copyright © 2007 John Wiley & Sons, Ltd.
On transient behaviours of slotted CSMA protocols
Authors: Jereb L. , Marsan M. Ajmone
Published: July 2007

CSMA protocols have been extensively studied under the assumption of an equilibrium condition. The results obtained in this manner provided useful insight for the development of packet radio and local area networks for the transmission of bursty data. The integration of isochronous and bursty traffic in the same network may, however, make the equilibrium assumption unrealistic, for example when fixed‐length frames are defined, only a portion of which is devoted to the transmission of bursty data according to a CSMA protocol. In such cases, it is necessary to study the protocol behaviours in fixed‐length time segments. This paper presents a technique for the analysis of slotted CSMA protocols in such an environment. Definitions for the transient throughput and transient average packet delay are introduced, and closed form expressions are derived for non‐persistent and 1‐persistent CSMA and CSMA/CD protocols with arbitrary distribution of the packet length. Numerical results help in the visualization of some interesting phenomena, peculiar to the CSMA operations in finite‐length intervals.
A methodological approach to BISDN signalling performance
Authors: Hou X. , Kalogeropoulos N. D. , Lekkou M. E. , Niemegeers I. G. , Venieris I. S.
Published: July 2007

Sophisticated signalling protocols are required to properly handle the complex multimedia, multiparty services supported by the forthcoming BISDN. The implementation feasibility of these protocols should be evaluated during their design phase, so that possible performance bottlenecks are identified and removed. In this paper we present a methodology for evaluating the performance of BISDN signalling systems under design. New performance parameters are introduced and their network‐dependent values are extracted through a message flow model which has the capability to describe the impact of call and bearer control separation on the signalling performance. Signalling protocols are modelled through a modular decomposition of the seven OSI layers including the service user to three submodels. The workload model is user descriptive in the sense that it does not approximate the direct input traffic required for evaluating the performance of a layer protocol; instead, through a multi‐level approach, it describes the actual implications of user signalling activity for the general signalling traffic. The signalling protocol model is derived from the global functional model of the signalling protocols and information flows using a network of queues incorporating synchronization and dependency functions. The same queueing approach is followed for the signalling transfer network which is used to define processing speed and signalling bandwidth requirements and to identify possible performance bottlenecks stemming from the realization of the related protocols.
An object‐oriented analysis of a BISDN control system with a focus on the UNI protocol object
Authors: Ouibrahim H. , Pattenier F. J.
Published: July 2007

The control system of a BISDN network will undoubtedly be very complex to design, implement and maintain. Its complexity has led researchers to look for ways of breaking down the problem into smaller and manageable parts. This has motivated the use of an object‐oriented approach to analyse and comprehend the BISDN control system.

This paper thus presents an object‐oriented analysis (OOA) of a BISDN control system. This analysis is based on a method introduced by Coad and Yourdon and comprises five steps. All five steps, namely identifying subjects, identifying objects, identifying structures, defining attributes, and defining operations, will be worked out in detail with an emphasis on the user network interface (UNI) signalling protocol object. Four subjects, nine objects, and three structures are identified in the problem space at hand. This structuring offers a framework to analyse in detail the three aspects, data, structure and dynamic behaviour, of the UNI signalling protocol.

A parallel between this approach and the well known approach used by the International Telecommunication Union (ITU) for specifying signalling protocols and contained in Recommendation I.130 is drawn.

The Coad and Yourdon OOA approach applied to a BISDN control system can be used for the analysis of different aspects of such systems. This paper focuses on the UNI signalling protocol object which leads to a complete specification. Any protocol resulting from such analysis can be claimed to be object‐oriented protocol. This approach offers modularity and thus offers a way of structuring the problem space into identifiable objects and data. Full benefits of object orientation can be gained only in the consistent use of object orientation throughout all steps in the development process. The proposed approach allows one to create libraries of generic procedures which can be reused in specific implementations.
A distributed media access protocol for packet radio networks and performance analysis. Part 1: Network capacity
Authors: Pond Lawrence C. , Li Victor O. K.
Published: July 2007

A distributed time‐slot assignment protocol is developed for a mobile multi‐hop broadcast packet radio network, using time division multiple access channel access and virtual circuit switching. The protocol eliminates the single point failure mode of centralized network management and the delays of centralized processing. It is applicable to the user‐to‐user communications functions of such systems as the U. S. Army's enhanced position location and reporting system (EPLRS). The important functions of the distributed protocol, including time‐slot assignment, virtual circuit set‐up, and network synthesis, are identified, and implementing algorithms are presented and verified. The performance analysis of the protocol is divided into two parts. In this paper, Part 1 of the performance analysis, the capacity of a network using this protocol is studied and a tool is developed to design the network capacity by trading off among the network area, the transmission range, and the number of packet radio units. Since these results are not in closed form, numerical results provide insight into these parameters. In Part 2 the network set‐up time and network data rate are analysed and a hierarchical architecture for the distributed protocol is proposed and analysed.
Analysis and design of a DPSK optical heterodyne receiver in the presence of laser phase noise and frequency detuning
Authors: Gini Fulvio , Luise Marco , Reggiannini Ruggero
Published: July 2007

This paper is concerned with the analysis and design of an improved differential heterodyne optical receiver for differentially‐encoded binary PSK (briefly, DPSK) signals in a coherent lightwave communication system. In the first part of the paper, we discuss the relevant design criteria to be employed when dealing with asynchronous heterodyne receivers for ASK, FSK or DPSK optical signals. In particular, we introduce a convenient definition of the signal‐to‐noise ratio at the data detector input to be assumed as the system performance measure when the non‐negligible linewidth of the transmit/receive laser sources are to be taken into account. Following this design approach, we show that by properly modifying the traditional delay‐and‐multiply DPSK receiver, i. e. by allowing the delay to be a fraction of the symbol interval, we can considerably reduce the performance degradation caused by laser phase noise. We show thus that the superior power‐efficiency of DPSK can be traded in favour of a decreased sensitivity to phase noise through a proper choice of the differential detector delay. In this respect, our results reveal that DPSK may still be competitive with other modulation formats even with non‐negligible linewidth sources. In the last part of the paper, the behaviour of the optimized DPSK, ASK and large‐deviation FSK data demodulators in the presence of a quasistationary frequency detuning of the local laser is also discussed under the same set of conditions as in the previous analysis. The results can be employed to derive accurate design requirements for the AFC loop of the receiver.
Medium access control for asynchronous traffic in the AMNET lan
Authors: Goodall D. S. , Burston A. K.
Published: July 2007

This paper describes a proposed medium access control (MAC) protocol for managing asynchronous traffic within the AMNET LAN. We have called the protocol the buffered access cycle (BAC) since it employs a centrally controlled access cycle in combination with an insertion buffer. The resulting mechanism allows asynchronous traffic to co‐exist with higher priority synchronous traffic, which is managed separately, and make best use of any available bandwidth. The protocol produces utilization figures superior to those of a centrally controlled access cycle scheme without an insertion buffer. Included in the paper are a description of the proposed scheme, a description of the AMNET protocol for managing synchronous traffic, and the results of various simulations.
Optimum frequency reuse in mobile telephony systems
Authors: Kazantzakis M. G. , Demestichas P. P. , Anagnostou M. E.
Published: July 2007

The reason whycellularmobile telephony systems exist is that they allowfrequency reuse.Dynamic allocation algorithms improve the network efficiency and the service quality. Dynamic allocation is closely related to the followinginstantaneous allocationproblem: given a number of channels (frequencies), a cell structure and the number of calls to be accommodated in each cell, find the optimum allocation of channels to cells subject to restrictions concerning the distance of cells, where the same frequency can be reused. In this paper we formulate and solve this problem by showing that it can be reduced to a 0–1 programming problem. Finally we present results, and draw subsequent conclusions.
The split‐switching network (SSN): A high‐performance multicast ATM switch
Authors: Awdeh Ra'Ed Y. , Mouftah H. T.
Published: July 2007

This paper proposes a new high‐performance multicast ATM switch architecture. The switch, called thesplit‐switching network(SSN), is based on banyan networks. The SSN achieves multicasting in a way that is non‐typical for banyan‐based switches: copying and routeing of multicast cells are carried out simultaneously and within the same fabric. Thus, cells are copied only when needed as they traverse the switch towards the appropriate output ports. The SSN consists of successive spliting stages, and buffering is provided in front of each stage. The SSN is non‐blocking with complexity of order Nlog2/2N for a switch of sizeN, and is characterized by distributed and parallel control. The throughput‐delay performance of the SSN is shown to be similar to that of a non‐blocking output‐buffering switch under different mixtures of unicast/multicast traffic. In particular, the SSN achieves a maximum throughput of 100 per cent and the cell delay and delay variation remain small for loads just below the maximum throughput.
Performance of adaptive token allocation in the leaky bucket
Authors: Yang Oliver W. W. , Mouftah H. T. , Ko C. P.
Published: July 2007

The leaky bucket is a popular method that can regulate traffic into an ATM broadband network. This paper examines a simple but innovative modification that would also provide priority to access the network. This is done by requiring cells of different classes to obtain different numbers of tokens before receiving their services. As a step further, a dynamic scheme can be used in which the tokens allocated to each class are changed according to the traffic load. Performance evaluations of mean cell delays and cell loss probabilities are obtained to provide insight into the behaviour of the system and to provide guideline for furture design.
ISDN loop extension using a mid span amplifier
Authors: Erker Greg J. , Dodds David E. , Krzymien Witold A.
Published: July 2007

The 5·5 km range of the basic rate ISDN loop has been extended by using a negative impedance amplifier and by using a 2 wire/4 wire (2w/4w) amplifier. The negative impedance amplifier extends the range of the loop by 1·0 km, whereas the 2w/4w amplifier extends the range by 1·5 km at the expense of increased complexity. As part of the amplifer design, a resistor/capacitor network has been developed which closely matches the characteristic impedance of telephone cable. Error rate tests have been conducted using various lengths of cable and an operating ISDN line.
Link failure detection for maintaining session continuity in packet data networks
Authors: Kumar Anurag
Published: July 2007

A link failure in the path of a virtual circuit in a packet data network will lead to premature disconnection of the circuit by the end‐points. A soft failure will result in degraded throughout over the virtual circuit. If these failures can be detected quickly and reliably, then appropriate rerouteing strategies can automatically reroute the virtual circuits that use the failed facility.

In this paper, we develop a methodology for analysing and designing failure detection schemes for digital facilites. Based on errored second data, we develop a Markov model for the error and failure behaviour of a T1

T1 carrier, the lowest level in the plesiochronous digital carrier hierarchy in the United States. AT1 carrier has a payload of 24 64Kbps PCM channels.

trunk. The performance of a detection scheme is characterized by its false alarm probability and the detection delay. Using the Markov model, we analyse the performance of detection schemes that use physical layer or link layer information. The schemes basically rely upon detecting the occurrence of severely errored seconds (SESs). A failure is declared when a counter, that is driven by the occurrence of SESs, reaches a certain threshold.

For hard failures, the design problem reduces to a proper choice of the threshold at which failure is declared, and on the connection. reattempt parameters of the virtual circuit end‐point session recovery procedures. For soft failures, the performance of a detection scheme depends, in addition, on how long and how frequent the error bursts are in a given failure mode.

We also propose and analyse a novel Level 2 detection scheme that relies only upon anomalies observable at Level 2, i.e. CRC failures and idle‐fill flag errors. Our results suggest that Level 2 schemes that perform as well as Level 1 schemes are possible.
On the reachability of discrete‐time compartmental systems with nonnegative input constraints
Authors: Kusuoka Hideo , Maeda Hajime , Kodamas Shinzo
Published: July 2007

This paper investigates the properties of reachable sets of discrete‐time compartmental systems. The discrete‐time compartmental system is characterized by the non‐negativeness of all coefficients of its system state equations and its inputs.

The paper first deals with the properties of reachable sets at finite sampling times of general ordinary linear discrete‐time systems with simple non‐negative input, and the n.a.s.c. under which the reachable set coincides with the maximal reachable set at finite sampling times. Then, it deals with the characteristic polynomial representation of state transition matrix and the properties of the maximal reachable set. After showing the properties of reachable sets of compartmental systems, the paper discusses the drug kinetics problem as an example of the analysis of reachable sets.
A new iterative method in numerical pattern synthesis
Authors: Tokumaru Shinobu , Yoshimura Hitoshi
Published: July 2007

In general, in the problem of directivity synthesis, the objective function for optimizing the gain and conditions for constraining the fields of the sidelobe levels must be taken into account together. These kinds of problems had been solved by the so‐called quadratic programming method among other mathematical programming methods, but when the element number becomes large, so must the sidelobe constraint condition number. Thus this method becomes rather difficult in practice.

In this paper such a directivity synthesis problem will be formulated as an optimization problem in which Lagrange multipliers will be employed for the objective function which is in quadratic form. Thus, the problem will be solved approximately by introducing Lemez' best‐approximation concept; the solutions will be obtained by use of an extremely simple and rapidly converging iteration‐numerical approach.

Although this approach may occasionally yield solutions which are not optimized, its results will be sufficiently close to the optimized solution that it is a practical one. Since, especially, the iteration calculations can be attained by merely considering simultaneous equations, as a computer‐oriented method, this approach can yield solutions more rapidly than the quadratic programming method for a large number of elements.
Contactless measurement of sheet conductivity and mobility of semiconductor wafer by using eddy curent
Authors: Horiguchi Fumio , Furukawas Seijiro , Sugii Toshihiro
Published: July 2007

This paper describes a contactless method for measuring sheet conductivity and mobility of the semiconductor wafer. In comparison with the conventional 4‐probe and van der Pauw methods, no ohmic contacts are needed and therefore no nondestructive measurement error exists. Previously, the quantitative relations of the conductivity and mobility with the distributions of eddy current to be measured and Hall voltage, as well as the voltage for eddy current detection were not clear. In this paper, by considering the mutual inductances between the coil and wafer, these have been clarified. The proposed theory and experimental results are compared and their agreement confirmed. The dependence of the voltage for eddy current detection on frequency is also investigated and optimum frequency for measurement derived. The equivalent circuit is used for Hall voltage detection. Optimized electrode dimensions are shown to exist for maximizing the detection voltage and are verified by experiment. Consequently, this method enables absolute measurements and, concerning the mobility measurement, it has clarified the relationship between the measurement sensitivity and resolving power.
A magnetooptic video disk readout method using a pair of polarized laser beams
Authors: Ishii Akira
Published: July 2007

A new symbol readout method employing two readout laser beams that intersect at a specified angle on the magnetic medium surface and are orthogonally polarized with respect to each other is proposed. The diffracted light signal is detected in reproducing the FM video signal, that is, it is recorded thermomagnetically on a magnetic film as recording medium (e.g., a rotating disk memory) using magnetooptic effects. The effects of the readout frequency characteristic, and the readout beam defocus are analyzed. The diffracted light of the high‐frequency signal generated by the signal recording track overlaps the zero‐order diffracted light. By adjusting the intersecting angle of the readout laser beams in such a way that sufficient overlapped light is obtained, the higher‐frequency limit of the readout frequency characteristic can be emphasized. Further, in order to obtain flat FM demodulator characteristic, the needed readout frequency characteristic that attenuates linearly in the neighborhood of FM carrier frequency is realized easily by optical means. As a result of greater emphasis on the larger limit the signal‐to‐noise ratio is improved. It is possible to reduce the output of the readout laser light source to less than half, when compared to the conventional magnetooptic readout methods employing a single beam.
Nonreciprocity of saw velocity on a magnetized ferrite substrate
Authors: Shimizu Yasutaka , Hasegawas Ken , Yamada Takashi
Published: July 2007

Surface acoustic waves (SAW) propagating on piezoelectric materials are now utilized in practical devices such as filters and signal processing. However, only a few papers were reported on SAW propagation on magnetic materials. In this paper, the propagation characteristics of magnetoelastic Rayleigh waves on the YIG substrate are treated experimentally for the bias configuration where dc magnetic bias field is tangential to the substrate surface and oblique to the direction of propagation. The saturation magnetization of the YIG ferrite used for the experiment is 250 and the Rayleigh waves were excited and received by using ZnO thin‐film transducers. In this configuration, the nonreciprocity of surface wave was observed. Its velocity to the forward direction was found to be different from that in the reverse direction. The maximum amount of nonreciprocity obtained experimentally in this paper was approximately 150 ppm. This value is too small for the application, but the unidirectional transducer, the isolator and the device similar to the circulator may be constructed by using the nonreciprocal characteristics of surface wave velocities.
Characteristics of an optical branching waveguide in linbo3
Authors: Mitsunaga Kazumasa , Masuda Masamitsu , Koyamas Jiro
Published: July 2007

This paper describes a theoretical analysis of branching losses in planar branching waveguides with optical switching is achieved by the optoelectronic effect of Ti‐diffused LiNbO3. An experimental study of the characteristics of the above element shows that, although the guided optical waves are subjected to losses due to various causes, the major loss can be suppressed effectively by taking the branching angle at 1 or less; the major loss is caused by the tilt of the optical equiphase surface and the “blunting” of the branching fork tip. It is possible to obtain an optical switching extinction ratio of ‐20 dB or more. In addition, it becomes obvious that the blunting on the branch front may result in loss increase where no voltage is applied. Furthermore, an experimental element was manufactured to study the practical characteristics of the hereby proposed branching waveguide. The result obtained by the measurement agrees with the estimated characteristics by the analysis.
Design theory of a distortionless nonreflective all‐pass impedance transformer using a nonuniform transmission line
Authors: Ito Chiaki , Kasais Hisashi , Sato Risaburo
Published: July 2007

Traditionally, the use of nonuniform transmission lines has been suggested for designing a wideband impedance transformer. However, no rigorous design method has been found. This paper proposes two rigorous methods each for designing distortionless, nonreflective all‐high‐ and low‐impedance transformers which are simple and of minimum attenuation, based on the distortionless conditions of the voltage and current waveforms in a nonuniform transmission line. The methods make only C(x) or L(x) of the primary constants of the transmission line uniform. It was found sufficient that these distributions be of square or inverse square. According to the design method, we designed a 50 to 75 ω transformer which is subsequently modeled by a 100‐stage ladder network. We performed experiments in the dc ‐ 10 MHz frequency domain as well as in the time domain. The experiment has been proceeded in accordance with the theory and the effectiveness of the proposed design method and the validity of the distortionless theory of nonuniform transmission line are proved.
Evidence for the existence of the craik–o'brien effect in human color vision
Authors: Isono Haruo
Published: July 2007

In human vision there occurs an interesting illusion called the Craik‐O'Brien effect. When a counter line has an appropriate distribution of brightness, even though there is no physical contrast, from the contour information a contrast is produced and an object can be seen. It is hoped that this visual phenomenon can be utilized by an engineering application to improve the quality of TV pictures and condensation of the transmission signals In the past, this phenomenon was studied as an illusion of brightness (no color), and the Craik‐O'Brien effect was not found in the case of color. Hence, its characteristics were unclear . Using an electric edge pattern generator and a color CRT, the author has in this case generated monochromatic colors (R, G, B) and hue edge patterns whose luminance is constant but of different colors and hues. The response of the subjects was measured by psychophysical methods. The results proved the existence of the Craik‐O'Brien effect in the case of chromatic counter information and the author elucidated its characteristics. In the case of monochromatic edge patterns, the effect is significant and its basic characteristic is close to that of the brightness Craik‐O'Brien effect. On the other hand, in the case of chromatic edge patterns, although the pattern existed, the contrast produced by the color was less significant when compared with the contrast produced by the brightness and was only a fraction of the contrast produced by the brightness Craik‐O'Brien effect.
Evaluation on dynamic steps of path hunting in t‐s‐t types of switching networks
Authors: Saito Tadao , Inose Hiroshi , Oginos Nagao
Published: July 2007

In a high‐speed PCM switching system, it is possible to achieve low blocking probability and high switching efficiency due to the large number of available time‐division paths between a given inlet and outlet pair. However, in order to achieve high efficiency, the central control processor of the system must perform more intensive path hunting. In conventional switching network design, the efficiency of the network is a prime concern while the control procedure for path hunting is often overlooked. Depending on the type of switching network, the trade‐off between the efficiency of the network and the complexity of the control procedure should be considered. The main purpose of this paper is to evaluate the path hunting procedures for T‐S‐T type of time‐division switching networks. The path hunting procedure will be evaluated on the basis of theoretical analysis and simulation of typical switching networks. It will be shown that there is a trade‐off between the efficiency of the network and the complexity of the control procedure.
Registration techniques on warpage wafer for eb direct writing
Authors: Sugiyama Naoshi , Otsukas Hideo
Published: July 2007

In the manufacture of integrated circuits by electron‐beam direct writing technique, the pattern shift caused by wafer warpage has been corrected by placing the reference mark on entire chips on the wafer and registration has been made for each chip. In the model experiment proposed in this paper, the number of registrations can be reduced significantly if model points are defined on the wafer. The pattern shift can be estimated for the entire wafer surface by the cubic interpolation method using model points and registration results.

A high‐voltage, high‐current MOSFET has been realized as a new type of power transistor. Major problems in the development were how to increase the breakdown voltage and how to reduce the on‐resistance. The latter arises from the series resistance in the gate offset region, which is employed to obtain a high breakdown voltage. A structure with a “field‐plate” overhanging the gate electrode is proposed to reduce the series resistance and to increase the breakdown voltage. A one‐dimensional analysis of this structure is given.

Important consequences of the field‐plate are that the ion‐implemented region underneath it is pinched‐off and that the pinch‐off voltage can be kept low even at ion‐implementation dosage high enough to reduce the series resistance. Both p‐channel and n‐channel power MOSFET's have been fabricated. Maximum current of 10 A, a drain breakdown voltage of 200 V, and a transconductance of 1 S have been obtained.

A theoretical consideration has been given to the performance comparison between the MOSFET and bipolar transistor as power devices based on their operation principles. It is shown that the MOSFET has good prospects in high‐power, high‐speed applications due to its inherent thermal stability and better switching characteristics, but there is still room for technological improvement in its transconductance and on‐resistance.
Computer‐aided design of the norton transformation on reactance bandpass ladder filters
Authors: Hibino Masao , Matsushimas Toshiaki
Published: July 2007

The CAD method for Norton transformation is presented. Norton transformation has been considered as an important process in the reactance bandpass filter design. It is an equivalence transformation process for easy realization of the element of practical filter. The previous method requires certain designer experience and determines the optional element values by iteration and human interaction. This paper presents a method in which the research method is done by random number and no designer experience is ever required. This method conducts Norton transformation automatically. It has made it possible to automate the complete engineering design of the filter. First, the Norton transformation is outlined, the method giving the circuit topology convenient for program is discussed, and based on the method for topology the algorithm is presented. Finally, how to choose several parameters will be investigated for the search method for several examples. Also given is the design example presented in the computer output.
A study of branching phenomena in nonautonomous piecewise‐linear systems with asymmetrical restoring force in the case of the external force with a sum of several harmonics
Authors: Shirao Yoshiaki , Kido Masao , Kaji Nobuyuki , Moritani Takao
Published: July 2007

In the study of nonlinear oscillations, it is well known that, in general, the fundamental harmonic solutions are either in phase with the external force or in opposite phase with it in a lossless system represented by a second‐order differential equation for a single external force. This paper considers a system with asymmetrical restoring force for several external forces. In the following steps, it is shown that there exist solutions in this system which are neither in‐phase nor in opposite phase with the external forces. First, we consider a second‐order system with an asymmetrical restoring force composed of two line segments as an asymmetrical system, and obtain a periodic solution in the same way as in the case of a single external force. The stability of the obtained periodic solution is studied by using Hill's equation and the boundary conditions of the stable and unstable regions are shown clearly. Moreover, the branching phenomena in the boundary are analyzed in four cases. In three of these four cases, there are branching or jump phenomena of the harmonic solutions of fractional orders (2n + 1) /2 (n = 0, 1, 2) due to asymmetry as in the case of a single external force. However, the fourth case shows the branching phenomena of periodic solutions which are neither in‐phase nor in opposite phase with the external forces. The results of numerical analysis and the appropriateness of the analysis are shown.
An analysis of shielded pair cable for tight coupling by conformal mapping and its application to directional couplers
Authors: Kami Yoshio , Nagasawa Yoji , Sato Risaburo , Arakawa Teruaki
Published: July 2007

The shielded cable with close inner conductors is different from the conventional local cable and can be applied to directional couplers. In this paper, for the purpose of obtaining tight coupling, we investigated the cable in which two inner conductors are very close. In particular, we consider the finishing with very fine conductors for small power application. In this case, it is necessary to use a second dielectric in order to maintain the space between the inner conductors, resulting in an inhomogeneous media. For the solution of such a shielded cable pair by quasi‐TEM mode approximation, we use the method of conformal mapping. Also, the measurements of the cable constants and the restrictions of a directional coupler by TEM approximation are described. The approximate equations obtained are applicable to the design of a cable with tight coupling below about 10 dB and the trial production of 3 dB‐ and 5 dB‐cables was proved to be satisfactory. The directional couplers using these cables are possible in practice and we expect to see their application in the VHF and UHF bands.
Microwave transmission‐type dielectric resonator transistor oscillator
Authors: Hayasaka Takeshi , Shinozaki Satoru , Sakamoto Kazuo
Published: July 2007

The step electrode transistor or GaAs Schottky‐barrier field‐effect transistor can oscillate above 6 GHz. A high Q and good temperature‐property dielectric resonator has been developed. Due to the microwave transistor and the dielectric‐resonator, the frequency stability can be made superior and noise characteristics better in the microwave oscillator, and integrable oscillator can be obtained. For the microwave oscillator design, the output power, stability, tunability and noise characteristics must be known. Therefore on using the negative‐resistance of the microwave transistor and transmission type of dielectric resonator, operation is analyzed for the oscillator using the transmission‐type dielectric‐resonator taken as an out‐of‐band resistive termination. First, changes of the oscillation power and frequency at the center frequency due to the negative resistance property are clarified; the frequency stability and oscillation power variations with the resonance frequency spread are considered; also clarified is the relation between the frequency stability and tunability. Finally, the noise comparisons among the above transistors and other solid‐state devices in the 7‐GHz band are presented.
Asymptotic solutions for the two‐dimensional diffracted field
Authors: Hongo Kohei , Nakajima Eiji
Published: July 2007

A simple formula is derived to estimate the asymptotic field diffracted by an infinitely long cylindrical object with an arbitrary cross section when an arbitrary cylindrical wave with directivity is incident. In the analysis, the problem of diffraction of a cylindrical wave by an infinitely long slit is formulated by means of the Kobayashi‐Nomura method, and an asymptotic series solution is derived with respect to the distances between the source and the scatterer and between the scatterer and the observation point. The solution is given in the form of a diffraction pattern function for the plane wave incidence and its derivative. The method is applicable to any diffraction (or scattering) problems of the object for which the pattern function is known. The result is applied to the problems of diffraction by a half‐plane and a wedge and of scattering by a circular cylinder, and practical representations are derived. For the half‐plane problem, the results are compared with those derived by other methods and complete agreement is confirmed. Numerical calculations for the slit diffraction problem and scatterings from the cylinder result in accurate results even when the distance between the object and the source is extremely small, as long as the second or the third term is taken into consideration. The method is believed to be an effective one.
Time domain and realization of a class of digital hybrid filter
Authors: Shinnaka Shinji
Published: July 2007

This paper describes a time‐domain design and realization of a digital hybrid filter with a specific cutoff frequency. The proposed realization is obtained by adding a single multiplier in a feedback loop to the low‐pass or high‐pass FIR filters with linear phase. The resulting hybrid filters can have the following improved frequency response: (1) Increased attenuation in the stop‐band (compared to that obtainable with a Kaiser windowed FIR filter of the same order) for the same transition bandwidth; (2) almost constant amplitude response in the stopband and no zero‐cross ripple; (3) no degradation of phase linearity in the pass‐band; and (4) almost constant phase response in the stopband. Also the hybrid filter designed and realized in this way is always stable and does not generate limit cycles. The time‐domain design and realization of digital hybrid filters of this class are introduced and a design example of a low‐pass hybrid filter is given.
Lumped‐element representations of lossy multi‐wire lines
Authors: Kunieda Hiroaki
Published: July 2007

Lumped‐element representations are derived for lossy multiwire lines using simple circuit matrix with the assumptions that (1) phase constants of all transmission modes are identical, and (2) their attenuation constants are independent of frequencies. Since these assumptions are valid in the limited frequency range, simplified representations of lossy multiwire lines are derived in the vicinity of a quarter‐wavelength frequency. As an application of narrowband equivalent representations, analysis and design of lossy interdigital‐line filters of narrow‐band are investigated.
Optimized interpolation of discrete picture signals
Authors: Kinuhata Kouji
Published: July 2007

This paper describes the optimization of linear interpolation of picture elements in terms of least mean square error for pictures of a square array of elements. Two kinds of models are assumed for autocorrelation function m, n which is defined as the correlation of two elements separated m picture elements in a horizontal direction and n picture elements in a vertical direction. One is a homogeneous model in which m, n is given by the equation m, n

In the interpolation of the picture element at the point not sampled, the optimum interpolation can be achieved by the linear combination of the four picture elements nearest to the point to be interpolated. This is strictly true in the case of an inhomogeneous correlation function and approximately true in the case of a homogeneous correlation function. On the other hand, in the interpolation of the picture element at the sampling point, the interpolation can be optimized by the linear combination of eight picture elements around the point to be interpolated. This is strictly true in the case of an inhomogeneous correlation function and approximately true in the case of a homogeneous correlation function.

Using the above results, interpolation techniques in “standard conversion in broadcasting television signals” and “system conversion from video phone signal to broadcasting television signal” are reviewed, and the pictures processed with the interpolation techniques are evaluated.
Theoretical analysis of distortion of simultaneous transmission systems for picture and narrowband signals
Authors: Morimoto Sei
Published: July 2007

This paper presents formulas for calculation of the distortion noise in picture and subcarrier FM transmission. The distortion is calculated from the transmission channel characteristics at the sideband of the FM wave which is expanded in Bessel function. FM and PSK are considered as the subcarrier modulation. The spectral models for the picture brightness signals and color signals are approximated by e‐aΔ at frequency Δ.

The main results include: (1) the calculation of the distortion due to the differential gain (DG); (2) the calculation of 16 different kinds of distortions; and (3) the application to TV‐speech multibroadcasting, two‐picture simultaneous transmission, and picture‐telephone simultaneous transmission.
16‐qam carrier recovery with selective gated phase‐locked loop
Authors: Horikawa Izumi , Saitos Yoichi
Published: July 2007

It is important for the 16QAM carrier recovery circuit to have low phase jitter as well as only four stable phase points. In this paper, a novel carrier recovery with selective gated phase‐locked loop (PLL) is proposed which uses only the error information of the 4PSK signal and an identical phase signal; its construction and noise characteristics are also described. First, a concrete construction based on a working priciple and digitalized circuitry is given. Next, the phase jitter due to additive white Gaussian noise in a carrier tracking loop with binary phase comparator (PC) characteristic is analyzed using an equivalent linearization technique; also, it is shown that the carrier recovery loop can be described in a linear model of the past by introducing equivalent linear gain, equivalent input noise and the degradation factor caused by the symbol error. From this study, we conclude that with the selective gated PLL, the phase jitter performance of the carrier recovery can be improved by about 6 dB over that of the carrier recovery without the selective gated PLL. This has enabled us to improve the phase noise, power density, locking characteristic, tracking characteristic, etc., by about 100%. The noise characteristics are almost the same as that of 4PSK carrier recovery. The numerical calculations have been done for the equivalent PC. This recovery system does not have false lock points.
Recursive realizations of n‐th order fir filters with linear phase designed by (n‐1) point frequency sampling technique
Authors: Shinnaka Shinji
Published: July 2007

In determining approximately impulse responses of linear‐phase Nth‐order FIR filters by the N‐point frequency sampling method, the approximated impulse response is expressed as a sum of cosine or sine function series with phase shift corresponding to half series time width having sampled values as coefficients. On the other hand, the (N‐1) point frequency sampling method enables one to obtain the approximated impulse response in a form of a sum of cosine or sine function series without phase shift having sampled values as coefficients. In the recursive realization of triangular function series, the triangular function series without phase shift can be realized using a smaller number of multipliers than the triangular function series with phase shift. The (N‐1) point frequency sampling provides more effective recursive realization than the N‐point frequency sampling. If the normal form is used, the number of multipliers can be reduced by 33% and the processing speed and round‐off noise can be improved considerably.
Minimization of sensitivities in digital filters by coefficient conversion
Authors: Nishihara Akinori , Moriyama Yoshiaki
Published: July 2007

In digital filters, the response involves the error due to the finiteness of coefficient word lengths. This error is related to the coefficient sensitivity. In this paper, low‐sensitivity transfer functions are derived. With the smallest number of multipliers, the coefficients of the transfer function are derived as functions of multiplier coefficients using constant mij. Then the sensitivity of the amplitude characteristics for the multiplier coefficients is obtained as functions of real frequencients and constant mij and multiplier coefficients are determined by minimizing this sensitivity. Several low‐sensitivity transfer functions are derived and their circuits are presented.
Stability analysis of large‐scale composite systems using positivity condition of bilinear forms
Authors: Mori Takehiro , Kuwaharas Michiyoshi
Published: July 2007

This paper considers the positive definite conditions for bilinear forms, as obtained in the discussion of stability of discrete‐time feedback systems by Williams and Brockett, and derives several stability conditions for large‐scale systems with composite structures. Since the bilinear form includes the quadratic form as a special case, the result obtained includes typical traditional results derived from the definiteness condition for the quadratic forms. As a result of utilizing the bilinear form, the theorems in this paper can sometimes handle cases where the coupling among subsystems contains higher‐order terms, which could not be treated by most of the traditional theorems. Proofs for the theorems are given, including arbitrary parameters, but it is shown for some of the theorems that the conditions including arbitrary parameters can equivalently be replaced by algebraic conditions without such parameters. From these properties, the traditional conditions for stability including arbitrary parameters can be transformed into conditions without parameters. Several examples are shown in relation to the traditional results.