bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relaxing Phenomena in Negative Corona Discharge: New Aspects
Authors: Rahel J. , Pavlik M. , Holubcik L. , Sobek V. , Skalny J. D. 
Published: July 2007

AbstractTwo theories, explaining the time dependence of the negative corona discharge current in air, are confronted with new experimental results. The influence of the ozone concentration on the discharge current was experimentally confirmed in dry air and in mixtures of nitrogen with oxygen. Assuming that only the dissociative electron attachment to ozone molecule is a process being responsible for a reduction of the electron component in the total mean discharge current, the mean value of the electron attachment rate constant k = (3 ‐ 5.5) × 10−9 cm−3 s−1 was derived from the measured dependence of the discharge current on the ozone concentration. The calculated value of the rate constant k corresponds to the dissociative attachment of electron to ozone molecule via process e + O3 → products (O− or O−2 negative ions).
Density Measurements from the Asymmetry of the Lyman ζ Line in a Vacuum Spark Lithium Discharge
Authors: Podder N. K. , Clothiaux E. J. , Oks E. 
Published: July 2007

AbstractA lithium spectrum is obtained form vacuum spark discharges using a grazing‐incidence flat‐field spectrometer. Hydrogen‐like lines up to Lyman η are identified in the spectrum. The spectrum is analyzed, and it is found that the experimental line widths increase along the Lyman series. An asymmetry between the blue and red wings appears in the profile of the Lyman ζ line, and becomes significant in the profile of the Lyman ϵ line. A relatively new method is used to estimate an electron density of 1 ± 0.4 × 1018cm−3 from the experimental degree of asymmetry between the blue and the red wings of the Lyman ζ line. This result is compared with an analysis of the experimental widths of two optically thin lines, namely, Lyman δ and Lyman ζ. In this analysis an electron density of 1.2±0.5 × 1018cm−3 is deduced. The principal quantum number of Lyman η (n=8) is used in the Inglis‐Teller formula for the last line seen before the merging of the lines with the continuum, and the estimated electron density is found to be 2.0 × 1018cm−3 for the lithium plasma. Thus, it is demonstrated that the new method employing the asymmetry of the lineshapes in dense plasmas yields results consistent with the analysis of the widths of the lines. However, it requires obtaining the profile of just one spectral line, which is a great advantage. The reference data on the Stark broadening of the Lyman ζ line is also tabulated, which was previously unavailable in the literature.
An Experimental Study of Noble Gas Isotope Separation by DC ArcDischarge
Authors: Akatsuka H. , Ohtsuki N. , Ezoubtchenko A. N. , Suzuki M. 
Published: July 2007

AbstractExperiments are undertaken on the isotope separation by DC discharge through a narrow capillary of gaseous neon, argon and krypton of natural isotopic abundance. It is confirmed that the heavier isotopes become enriched in the region of cathode, and the lighter isotopes in that of anode. The effect on the obtainable separation factor brought by differences in experimental conditions is examined by changing the capillary tube diameter, tube length, discharge current and discharge pressure. The separation factor improves with increasing the tube length and the discharge current, and with decreasing the discharge pressure and the tube diameter. Ion density and electron temperature are measured in the positive column to compare the present experimental results with existing theories. The order of the isotope enrichment factor is well explained by the theory of the ion diffusive friction force onto isotopically different neutral molecules, together with the theory of the ionization degree of the different isotopic species.
The ‘leaky bucket’ policing method in the ATM (asynchronous transfer mode) network
Authors: Niestegge Gerd 
Published: July 2007

AbstractThe new asynchronous transfer mode (ATM) will be used for the information transport in the future broadband network. An important function of the ATM network is bandwidth enforcement or policing. The so‐called ‘leaky bucket’ algorithm can be used to monitor and enforce the bit rate of a constant bit rate (CBR) connection. The parameters of the ‘leaky bucket’ algorithm depend on the bit rate of the connection and on the cell delay jitter. Sugestions for setting the parameters of the ‘leaky bucket’ algorithm are provided in this paper. Furthermore, a ‘dual leaky bucket’ algorithm is proposed to police the traffic parameters of a variable bit rate (VBR) connection. The ‘dual leaky bucket’ approach could also be used to define a VBR bearer service in the future broadband network.
An architecture for integrated networks that guarantees quality of service
Authors: Lazar Aurel A. , Temple Adam , Gidron Rafael 
Published: July 2007

AbstractA generic architecture for integrated networks that guarantees quality of service is described. The network has a mesh topology and a switching architecture structured according to the concept of asynchronous time sharing. This concept is based on a multiclass network model and asynchronous algorithms for allocating network resources. There are three traffic classes for transporting user information and a fourth class for network management and control. Resource allocation is resolved through time‐sharing and space‐partitioning algorithms.
Subscriber premises' network architectures in a broadband ATM environment
Authors: de Vleeschouwer A. 
Published: July 2007

AbstractIn future broadband networks residential and business users will be distinguished, each with their own characteristic requirements. Whereas business users almost exclusively need interactive switched services, the huge number of residential users, on the country, mainly aim at entertainment services, either switched or distributed, at a low, possibly fixed, price. Based on the user requirements a twotier SPN architecture is derived, consisting of a TDN (terminal distribution network) and a BBN (broadband backbone network).Alternative structures for TDN are analysed and compared. A passive tree solution is found to be most suitable for the above‐mentioned needs. Although the physical appearance may be quite different, all the given examples have a number of elements in common. This enables common components to be developed.Inside the SPN, especially the residential SPN, the absence of any channel aggregate in ATM is of great advantage. Only the total available bandwidth imposes a restriction on the set up of new calls. This is very important, because SPN encounters a wide variety of user needs, together with a relatively small amount of users. In order to preserve the advantages of ATM in the subscriber area, it is essential to bring ATM down to the terminal.
R‐net: A high speed fibre optics network with reservation access protocol
Authors: Al‐Wakeel Sami S. , Ilyas Mohammad 
Published: July 2007

AbstractThis paper proposes and describes R‐net, a network with a new reservation access protocol that is very suitable for implementation with optical fibre in high speed local area networks. In the operation of R‐net, a framing structure with variable length is superimposed on the network bus to bound the network medium access delay which is a highly desirable feature for real time applications. As long as the frame length constraint is not violated, the performance of R‐net network is not limited by operating data rate, and the utilization can be set to unity by choosing the appropriate network parameters. The proposed network has the advantage of efficient throughput approaching unity for most practical configurations, bounded delay, and at normal load, the network protocol has fair access for all nodes and allows dynamic bandwidth allocation between the nodes connected to the network bus. A performance (delay and utilization) comparison between R‐net and Expressnet is also presented.
Implementation of multipoint connections in an ATM switching network
Authors: Knorr Rudi , Wild Thomas 
Published: July 2007

AbstractThis paper presents the problems in the implementation of multipoint connections at switching level using the example of an ATM switching network. By choosing the proper routeing mechanism and the appropriate architecture of the switching element, a switching network can gradually be adapted to an increasing share of multipoint traffic. The first section describes the problems with the handling of multipoint connections within a multiple stage connection oriented switching network. In particular this refers to the routeing of the cells through the switching network. Several alternatives on this issue are discussed. Both, the selected approach based on a differentiated self‐routeing mechanism and the corresponding cell format are introduced. In the second part of this article several switch architectures are compared in respect of their multipoint capability. It is demonstrated that at present the most promising solution are switching elements based on the principle of central buffering. A single chip solution using this concept is employed in the presented switching network.
Initial deployment of fibre in the local network for narrowband use in Spain: Technology, engineering and cost
Authors: de la Iglesia R. Diaz 
Published: July 2007

AbstractThis paper covers: (1) the field trials, with fibre in the local network systems, being conducted in Spain and intended for delivery telephone‐based services to residential customers; (2) the technical and functional requirements of these types of system intended for commercial (regular) deployment to be started around late 1993/early 1994, and (3) the most relevant initial deployment scenarios and persubscriber investment aspects.The field trials are located in Madrid and in Barcelona: their rationale, technical characteristics and the lessons learned so far are described.Such trials are providing insight into what requirements and objectives are anticipated to be needed should such new technology be an actual alternative to copper‐based subscriber loops. The requirement for such fibre in the local network systems intended for regular deployment in the near term are indicated, including technical and functional requirements of the optical line terminals (OLTs) (at local exchanges) and optical network units (ONUs) (located near customer premises); transmission requirements and optical distribution network (ODN) requirements and design aspects. For starting regular deployment, three preferred scenarios are identified. The chief parameters affecting persubscriber investments are illustrated including the number of fibres per ONU, and the number of users being served from each ONU. It is shown that in order to achieve cost parity with copper loop (which requires an initial investment of between $600 and $800) a capacity of some 60 narrowband (64 kb/s) channels per ONU should be required.
Out of band signalling technique for passive optical networks
Authors: Eldering Charles A. , Alonso Antonio Martínez 
Published: July 2007

AbstractIn this communication we present a novel means of signalling between an out‐of‐service RT and the CO when connected via a passive optical network which contains other RTs in‐service using a TDMA protocol. A simple experiment using a non‐coherent receiver is used to demonstrate the technique.
Priority shaping of traffic streams sharing a policed virtual path in an ATM network
Authors: Reiss Leszek K. , Merakos Lazaros F. 
Published: July 2007

AbstractTraffic streams with differing service requirements, sharing a single contract for use of a policed virtual path in an ATM network, may be jointly shaped to make the best use of bandwidth available in the path. The shaper may use the information about the network policer to perform self‐policing with a form of priority service to ensure satisfactory levels of cell loss and delay for both real‐time and non‐real‐time traffic. Two such shapers are considered assuming a mean bit‐rate contract with the network in which a leaky‐bucket mechanism performs the policing function. The performance of the shapers is analysed using Markov‐modulated models of bursty traffic sources and stochastic fluid methods, and the analytical results are corroborated by simulations. The choice of the shaper type and optimization of the shaper design parameters are discussed using correlated and non‐correlated source models.
Transmission algorithms for a multi‐channel packet radio system with priority users
Authors: Papantoni‐Kazakos P. , Delic Hakan , Paterakis Michael , Liu Ming 
Published: July 2007

AbstractIn multi‐channel systems such as multi‐station packet radio networks or cellular radio, various user categories arise. In this paper, we propose that one portion of the users, named low‐priority, each be assigned a specific channel for their transmissions, whereas another portion, named high‐priority, may transmit through any of the channels via some channel selection policy. The main objective is to reduce delays of the high‐priority users without imposing heavy penalties on the delays of the low‐priority group. For the described system, we adopt a previously studied limited sensing random access algorithm and introduce two dynamic channel selection policies. We study the stability region and the delays induced by the system. The selection policies present the high‐priority users with a significant delay advantage and induce fair utilization of the transmission channels, without requiring any knowledge about the system state by the users. One of the selection policies induces high system throughput at the expense of implementation complexity and increased delays for the low‐priority users. The second policy is easier to implement but, although it does not penalize the delays of the low‐priority users, it reduces the system thoughput.
Satellite constellations for a multiple LEO satellite network
Authors: Usui Tomonori , Kawabata Tsutomu , Onozato Yoshikuni , Oka Ikuo 
Published: July 2007

AbstractRecently, research has been very active in communication networks that could service the entire globe by using multiple, low, earth‐orbiting satellites. This has been spurred on by progress in the field of digital communication technique, technical advances of satellite launching, and a decrease in the costs of small‐sized satellites.In this paper, the construction of low, earth‐orbiting satellite communication networks is discussed from the viewpoint of the design of orbits and satellite positions. First, a symmetric orbit model derived from the idea of regular dodecahedron is proposed. Next, two evaluation methods of satellite distribution are shown. One is the method of summing the squares of distances between satellites and their earth stations. This is a general evaluation method based on the satellite orbits and satellite positions. The other is an evaluation method of the coverage based on the altitude of satellites and the antenna angles of the earth station. This method is applied to the proposed symmetric orbit, and characteristics of different satellite deployments are discussed comparatively.
Systematic construction algorithm of fixed block‐length (d, k) codes
Authors: Tanaka Hatsukazu 
Published: July 2007

AbstractThis paper proposes a systematic construction algorithm for the fixed block‐length (d, k) code, which is important as the code for magnetic recording. The coding rate (coding efficiency) and the encoding/decoding algorithms are discussed. As a result of numerical calculation for the coding rate of the finite block‐length (d, k) code, it is very close to the capacity limit even for a relatively short block‐length code.It is shown also that the coding rate for the infinite block length agrees with the capacity. A systematic encoding/decoding algorithm for the finite block‐length (d, k) code is proposed, and it is shown that the algebraic encoding/decoding can be realized.By introducing the concept of state, the coding efficiency of (d, k) code can be improved drastically and the coding rate approaches very close to the capacity while observing the constraint for the (d, k) code. Although it can be applied for the peak‐shift error correcting (d, k) code, it is left for future study.
Number of degrees of freedom, fisher information, and frequency‐time products of a random process
Authors: Kikkawa Sho 
Published: July 2007

AbstractFirst, the number of n‐th order degrees of freedom (n‐th order NDF) of stationary random process is defined in terms of the sample moment of order n of a finite length sample. Correlation times and equivalent band‐widths are derived from the NDFs. It is shown that the second‐order NDF asymptotically approaches the degrees of freedom of a gamma distribution by which the distribution of the ample variance is approximated.It is shown also for the case of a Gaussian process that the first‐order NDF is the same as the standardized Fisher information about the mean; and, furthermore, the second‐order NDF of a Gaussian AR process is the same as the standardized Fisher information about the variance. A problem with the Fisher information is that it cannot always be calculated, which is not convenient from the practical viewpoint. Since the NDF defined in this paper is based on the sample moments, it can easily be calculated from the observed data. Further, from the NDF, useful features can be derived such as the correlation time and the equivalent bandwidth. Therefore, it is of practical use.Finally, for a Gaussian process, the significance of the approximation of the NDF by 2 WT, where W denotes the equivalent bandwidth and T is time duration, is discussed. It is shown, in particular, that the approximation error for the second‐order NDF decreases only slowly, depending on the logarithm of 2 WT. This result is interesting in examining the dimension of the signal space for each moment of a random process since the situation is the same as in the case where the dimension of the signal space for the deterministic signal is approximated by 2 WT.
Bifurcations of periodic solutions in nonlinear nonautonomous system with symmetry
Authors: Katsuta Yuuji , Kawakami Hiroshi 
Published: July 2007

AbstractSome of the engineering systems and physical systems described by a lumped element system have certain symmetries in the system configuration and nonlinear characteristics. In such systems, these symmetries are reflected to the state equations which become invariant with respect to the symmetric transformation of the state variables. The authors have reported symmetries in autonomous equations [1]. Similar discussions are possible to the nonautonomous system with a periodic external force. However, the discussion has to be extended due to the periodic external force.In this paper, the symmetry of the nonautonomous system with periodic external force and the symmetry of the periodic solution are discussed. It is shown that two types of symmetry should be defined for the analysis of a nonautonomous system. It is demonstrated also that, aside from certain exceptions, the symmetry of the autonomous systems can be discussed systematically. Further, a mapping representing the symmetry of the solution is defined and the quasi‐periodic solutions and chaos are classified according to the symmetry.
Coherent‐state representations for functionals of the wiener process and the poisson process
Authors: Ogura Hisanao 
Published: July 2007

AbstractBy an analogy between the theories of the Wiener functional and photon quantum field, such as the Wiener‐Itô expansion and the Fock‐space representation, a “coherent‐state” representation is introduced as a functional integral of nonorthogonal, overcomplete basis, corresponding to the coherent‐state representation of a photon field. A discrete‐state version is given to the “coherent‐state” representation in a form convenient for practical application.Analogously, a “coherent‐state” representation is established for functional of the Poisson process, where a remarkable analogy exists between the two. The Wiener‐Itô representation is derived from the coherent‐state representation by interpreting the coherent state as a generating functional of the orthogonal functionals.
Computer search of the best convolutional codes on the basis of weight distribution
Authors: Sakai Ryuichi , Kasahara Masao , Sasano Hiroshi 
Published: July 2007

AbstractAs the efficient methods to determine the weight distribution of the convolutional code, there have been proposed the high‐speed algorithm based on the tree search on the trellis [1] and the variational method based on the variation of the weight of the code word [2]. This paper proposes a method to determine the weight distribution of the convolutional code with the coding ratio 1:2 where an algorithm (called modified variational method), which is efficient and can easily be realized on the computer, is derived by modifying the variational method. It is shown that the modified algorithm has a better performance than the conventional method.Then an efficient method is proposed which searches the best nonsystematic convolutional code with the coding ratio 1 : 2, assuming the maximum likelihood decoding. The best codes are sought for the constraint length from 6 to 19 using the proposed method, and a large number of the best codes is shown which heretofore have not been known.
A theoretical study on the orthonormal discriminant vector method for pattern recognition
Authors: Hamamoto Yoshihiko , Kanaoka Taiho , Tomita Shingo 
Published: July 2007

AbstractDiscriminant analysis has a serious shortcoming, namely, that in the m‐class problems the maximum number of features is m ‐ 1. To overcome this shortcoming, Okada and Tomita proposed the orthonormal discriminant vector (ODV) method. In the two‐class problem, the ODV method is equivalent to the method of Foley and Sammon. Experimental results show that the ODV method is more powerful than discriminant analysis. However, no attempt has been made to investigate the properties of the ODV method theoretically.In this paper the properties of the ODV method are studied from a theoretical viewpoint. In particular, the condition that discriminant analysis produces an ortho‐normal coordinate system is discussed. Based on this condition, the ODV method is compared with discriminant analysis.
Realization of a monolithic integrator with improved high‐frequency response using a miller integrator and its application to filters
Authors: Ishibashi Yukio , Matsumoto Fujihiko 
Published: July 2007

AbstractRecently, various electronic devices have become smaller in size while being required to process signals at higher speed. Especially, monolithic integration of a high‐frequency active RC filter is expected.In this paper, a method is proposed for the design of a novel variable integrator in which a Miller integrator is introduced. It is demonstrated that, even though lateral PNP transistors are used, the high‐frequency characteristics are excellent.Next, the effect of the parasitic capacitance of the integration capacitor on the integration characteristics is investigated. It is shown that such an effect can be made negligibly small by an appropriate layout of the integration capacitor.Finally, by means of a circuit simulator PSPICE, the integrator and the third‐order Chebyshev lowpass filter designed with the integrators are simulated and the results are presented. Even though PNP transistors with a transition frequency of 7 MHz are used, good characteristics are obtained in a filter with a cutoff frequency of 2 MHz. In the case of a power supply voltage of 3.2 V and a cutoff frequency of 2 MHz. In the case of a power supply voltage of 3.2 V and a cutoff frequency of 2 MHz, the total harmonic distortion of the output voltage of the filter is less than 0.1 percent for the input signal voltage of 1 Vp‐p. Hence, the effectiveness of the proposed circuit is confirmed.