bluuebunny/crossref_metadata_2025_split huggingface dataset:
RADIAL MATRIX ELEMENTS WITH DIRAC’S FUNCTIONS IN THE THEORY OF FINE AND HYPERFINE STRUCTURES OF HYDROGEN-LIKE SYSTEMS
Authors: TARASOV V.F. 
Published: October 2004

Investigating the effects of fine and hyperfine structures of hydrogen spectrum there arises practical necessity to evaluate the different matrix elements with Dirac’s radial functions f and g; usually such matrix elements being evaluted approximately. The article deals with the study of relativistic matrix elements by a new method, i.e. with the help of Appell’s hypergeometrical functions F2(x, y) and their new properties. Such approach allows: (1) to get exact analytical expressions for these matrix elements by means of Appell’s F2 (and Clausen’s 3F2) functions; (2) to reveal “latent” symmetry of diagonal matrix elements of such types as 〈rk〉njl and 〈g|rk|f〉njl with respect to points k0=–3/2 and k0=–1/2, respectively, the above symmetry is connected with the property of Appell’s function F2(1, 1) mirror-like symmetry; (3) to prove that the diagonal and off-diagonal matrix elements in a “pole-domain” of Euler’s gamma-function are given exactly analytically by means of “nonorientable” series of type Ḟ2(x, y). The examples for the evaluation of diagonal matrix elements for the K- and L-shells and also of dipole matrix elements for Lyman’s series are obtained.
EFFECT OF DIELECTRIC PROPERTY OF HYDROUS DISPERSOID ON ELECTRORHEOLOGY
Authors: KAWAI Akiko , UCHIDA Kunio , KAMIYA Kunio , GOTOH Akihiro , YODA Satoshi , URABE Kei , IKAZAKI Fumikazu 
Published: October 2004

The effect of the dielectric property was investigated of titania and microcrystalline cellulose particles dispersed in a silicon oil on Electrorheology(ER). A commom understanding of the mechanism of ER is the electrical interaction by the interfacial polarization of dispersed particles. Block et al. reported the relaxation frequency of ER fluids, i. e. the rate of polarization, was very important to have an appreciable ER effect. We found that the free water on the cellulose and the titania particles dispersed in the silicon oil, which is respectively dehydrated below the temperature of ca. 110 and 300 degree centigrade, was necessary for an appreciable ER effect. The relation was measured between the water content and the dielectric properties such as dielectric constant ε ’ and dielectric loss factor ε ", as the water adsorbed on the particles was estimated to alter the dielectric properties of the ER fluid. Both the dielectric constant and the relaxation frequency, which is defined by the applied frequency for a peak of the dielectric loss factor, increased with the increase of the water content The relation was discussed between the ER effect and the dielectric properties.
TOWARDS UNDERSTANDING ER FLUIDS USING SALS/RHEOMETRY
Authors: Crosby Bryan J. , McLeish Tom , Block Harry 
Published: October 2004

This paper details work in Cranfield and Leeds Universities of making a stock of transparent ER fluids, which could later be utilised in a new optical electro rheometer (OER) to be assembled at Leeds University. Two basic routes were attempted. One was to use glass microspheres and the other was to use polymer spheres. In order to increase the strength of the ER effect, it was necessary to increase the volume loading while still maintaining sufficient transmission (about 75% over 2 mm). It was found to be possible to increase the ER effect quite substantially in some instances, and in others it was possible to get a near perfect refractive index match. It was not possible to combine both requirements in one fluid such that a high static yield stress was apparent in a transparent ER fluid. However one fluid was made which gave acceptable diffraction losses at high volume fractions, remained in suspension for extended periods and provide about 700 Pa yield stress at 4kV/mm and about 30% volume fraction viz: untreated poly(ethylene vinyl acetate) microspheres in Cereclor/bromonaphthalene/polystyrene solution. The OER being assembled at Leeds University is intended to record small angle light scattering (SALS) profiles, electrical and mechanical properties of ER fluids simultaneously. The OER is based around a DSR 500 machine purchased from Rheometric Scientific with quartz tools coated with transparent indium tin oxide(ITO), which is capable of measuring both steady state (DC) and oscillatory (AC) material parameters.
ERF Based Precision Linear Drive System
Authors: Tönshoff Hans Kurt , Stegmann Axel 
Published: October 2004

The design of clutches using electrorheological fluids (ERF) or magnetorheological suspensions (MRS) offers a new approach to precision linear drive systems based on the ‘inch-worm’ principle. This principle needs two clutches or controllable clamps and one (or more) elements to vary the distance between these clamps. To perform a caterpillar-like motion the actuators are controlled in a cyclic mode. This paper presents design elements, system structure and first results of motion performance of a prototype drive system. The presented linear drive combines the high resolution of piezo actuators, the unlimited travel of the ‘inch-worm’ principle and the clutch effect of ERF without a substantial mechanical excitation. The motion of the two clamps is controlled to move a stage in point to point mode or to follow a given velocity profile. Using two piezo actuators the stage can move continuously. Pre-loaded piezo actuators control the distances between the two clamps and the central slide. Each ERF clamp is designed as a set of thin parallel steel plate electrodes which interlock with a set of ground plates. Drive force limits are given by the maximum yield force of the clamps as well as by the relation of the actuator expansion and the ERF/MRS shear stiffness in “solid” mode.
Command execution in a heterogeneous environment
Authors: Korb J T , Wills C E 
Published: October 2004

As a user's computing environment grows from a single time-shared host to a network of specialized and general-purpose machines, the capability for the user to access all of these resources in a consistent and transparent manner becomes desirable. Instead of viewing commands as binary files, we expect the user to view commands as services provided by servers in the network. The user interacts with a personal workstation that locates and executes services on his behalf.
Executing a single service provided by any server in the network is useful, but the user would also like to combine services from different machines to perform complex computations. To provide this facility we expand on the UNIX notion of pipes to a generalized pipeline mechanism containing services from a variety of servers. In this paper we explain the merits of a multi-machine pipeline for solving problems of accessing services in a heterogeneous environment. We also give a design and performance evaluation of a general mechanism for multi-machine pipes using the DARPA UDP and TCP protocols.
An interactive test sequence generator
Authors: Ural H , Short R 
Published: October 2004

The interactive test sequence generator (ITSG) is a software tool which provides the capability of generating test sequences from logic specifications in an interactive manner. A logic specification is a collection of Horn clauses coded in Prolog describing the externally observable behaviour of a system. ITSG facilitates a controlled traversal of the execution paths described by a logic specification and is written in C_Prolog running under UNIX 4.2 on Vax 750.
In this paper, first the form of logic specifications is described and an outline of a logic specification for a protocol entity (i.e., protocol specification) is presented. Then, ITSG is introduced and its functionality is explained. As well, the possible usage of ITSG in constructing conformance test suites for protocol implementation testing is discussed and a simple scenario for developing a conformance test suite is presented.
Inter-organization networks: implications of access control: requirements for interconnection protocol
Authors: Estrin D 
Published: October 2004

When two or more distinct organizations interconnect their internal computer networks they form an
Inter-Organization Network(ION)
. IONs support the exchange of cad/cam data between manufacturers and subcontractors, software distribution from vendors to users, customer input to suppliers' order-entry systems, and the shared use of expensive computational resources by research laboratories, as examples. This paper analyzes the technical implications of interconnecting networks across organization boundaries.

After analyzing the organization context in which IONs are used, we demonstrate that such interconnections are not satisfied by traditional network design criteria of connectivity and transparency. To the contrary, a primary high-level requirement is access control, and participating organizations must be able to limit connectivity and make network boundaries visible. We describe a scheme based on non-discretionary control which allows interconnecting organizations to combine gateway, network, and system-level mechanisms to enforce cross-boundary control over invocation and information flow, while minimizing interference with internal operations.
Access control requirements such as these impose new requirements on the underlying interconnection protocols. We demonstrate such alternative interconnection protocols that support loose coupling across administrative boundaries and that accommodate the necessary control mechanisms. Message-based gateways that support non-real-time invocation of services (e.g., file and print servers, financial transactions, VLSI design tools, etc.) are a promising basis for such loose couplings.
VMTP: a transport protocol for the next generation of communication systems
Authors: Cheriton D 
Published: October 2004

The Versatile Message Transaction Protocol (VMTP) is a transport-level protocol designed to support remote procedure call, multicast and real-time communication. The protocol is optimized for efficient page-level network file access in particular.
In this paper, we describe the significant aspects of the VMTP design, including the VMTP treatment of sessions, addressing, duplicate suppression, flow control and retransmissions plus its provision for multicast. The VMTP design reflects a change in the use of computer communication as well as a change in the underlying hardware base for the next generation of communication systems. It also challenges certain established notions in the design of protocols.
TORNET
Authors: Vranesic Z. G. , Hamacher V. C. , Loucks W. M. , Zaky S. G. 
Published: October 2004

TORNET is an experimental local area computer network presently being designed and built in the Computer Group Laboratory of the Department of Electrical Engineering at the University of Toronto. The network consists of a number of local rings, each attached to a central ring. The local rings employ a variation on the slotted-ring format that uses a limited insertion technique to achieve reasonable response times for character traffic among many devices and small computers. Two fixed-length packet formats (one byte or 128 bytes of data) are used on the local rings. Only the longer format is used on the central ring which generally provides record level access to shared specialized equipment.
The main objective in the local ring design is a low-cost port for inexpensive terminals, sensors, etc. The paper concentrates on the functional characteristics of the local rings, including delay-throughput comparisons with other well-known ring schemes.
The cost of data replication
Authors: Garcia-Holina Hector , Barbara Daniel 
Published: October 2004

With the advent of data communication networks, researchers have been looking at the possibility of placing copies of a database at two or more nodes of a network. Such data replication is interesting because it makes the database accessible even when some of the nodes in the system fail. Furthermore, transactions which only read data may get faster access to the data when multiple copies exist.
Due to the complex and time consuming update protocols, and due to the additional required hardware, data replication has a definite cost. This cost factor is often overlooked in discussions on replicated data, so in this paper we examine some of the cost issues involved. We argue that the cost of replicating data is so high that only in very special cases will data be replicated at different nodes of a computer communication network and kept in a consistent state. We also discuss some alternate approaches to data replication (like data replication at a single node and shadow copies).
Distributed communications
Authors: Kamrad M. , Cross J. 
Published: October 2004

Communications among multiple Ada programs is a must, either as an explicit link or as an invisible link hidden beneath a distributed Ada veneer. Unisys has defined two Ada package specifications for inter-program communications, that are derived from the requirements developed at the Third International Workshop on Real-Time Ada Issues (RTAW3). Unisys is implementing these packages on several embedded real-time testbeds, both as standalone capabilities for application developers and as the communication layer supporting a distributed Ada system. These specifications are proposed as a basis for a secondary standard for inter-program communication for Ada9X.
This paper describes how these specifications match the RTAW3 requirements and the motivation for their features. Some details of the specifications are interspersed throughout the text, with a full specification contained in the appendix.
Basic elements of a network data link control procedure (NDLC)
Authors: Pouzin L. 
Published: October 2004

Existing transmission procedures have been devised to control transmission over wire-like channels, since it was the only widely available medium, usually telephone lines. New proposals discussed in ECMA or ISO are somehow ambiguous, as they give no hint as to which transmission medium is assumed. In fact, the proposed schemes assume a wire-like medium, although this is not mentioned.
New technologies, such as satellite links, or packet switching, present somewhat different characteristics, which are not taken into account in the present proposals for standardization. Since these technologies are on the verge of commercial applications, it seems desirable to investigate whether their specific requirements can be reasonably met by future standards. If it were not, then other standards would become necessary. On the other hand, it seems that procedures applicable to packet switching networks links are also satisfactory when used over wirelike links. Then it would make sense not to miss the opportunity to work out a single set of standards.
The present paper examines some characteristics of new transmission technologies, and puts forth some proposals.
A restructuring of X25 into HDLC
Authors: Pouzin Louis 
Published: October 2004

A major achievement of the standardization process has been the definition of a universal circuit interface (X21 or X21 bis) together with a universal transmission procedure (HDLC). This allows a large degree of compatibility between terminal equipments, regardless of configuration or communication media.
X25 departs from this approach as it requires specialized DTE's that could no longer operate in conjunction with other simple DTE's using an HDLC interface. DTE's and procedures operating on private or public circuits would not be able to communicate with DTE's operating on public virtual circuits. This situation would be chaotic and detrimental to the user interest.
Simple DTE's with single access have no need for an X25 interface. They can certainly establish a call using the X21 or X21 bis interface, and operate in packet mode with an HDLC procedure. In particular, DTE's operating in half-duplex mode, or in a multipoint configuration, cannot use X25.
An analysis of X25 shows that its packet level is redundant with other level. Its functions could be performed in taking advantage of the facilities already present in HDLC. On the other hand X25 contains undesirable functions which should be eliminated or made user options, as they are generating incompatibilities.
The proposal described in this paper has major advantages over the present X25 in providing compatibility between "real" and "virtual" circuits while using a standard HDLC interface for all DTE's.
Protocols for intelligent terminals
Authors: Barber D. L. A. 
Published: October 2004

For some time now most people associated with research computer networks have championed the concept of layered protocols. These are uniform rules of procedure that are intended to be obeyed by each of the different computer systems, connected by a network, in order to disguise their differences and so allow them to intercommunicate freely with each other. The concept is an attractive one and has now been taken up in various standards bodies with a view to agreeing standards for 'open networking' through the public data networks. In principle, if a suitable set of standards can be agreed, any computer system will be able to call any other one and interact with it to conduct a variety of transactions. however, the extent to which this will be true in practice has yet to be established.
The layered protocol approach has proved very effective at the lower levels, but could become cumbersome if it is pushed too far. If this happens, and clumsy standards emerge, large software packages will be required to implement them in each of the cooperating computers. Such packages will be more complex than is desirable for many of the simpler applications, and will add unnecessarily to operational overheads in the smaller systems. This note suggests an alternative approach that seems worthy of consideration in the light of recent advances in micro-electronics and the likely requirements of future systems.
In particular, for intelligent terminals with only one user active there will be less need for the multi-threaded protocols of today, but a greater emphasis must be given to simplicity, so that implementation and subsequent maintenance will be easy and cheap. Accordingly, free-form protocols are introduced, and advocated as a means of harnessing the intelligence of terminals together with the intelligence of their users to greater effect than has hitherto been common.
Computer communication standards
Authors: Chapin A. Lyman 
Published: October 2004

This is one of a series of reports on the state of affairs in the communication standards arena. The development of high-quality standards for networking services, protocols, and interfaces has taken on a new urgency in the past few years with the rapid evolution of communication technologies and system architectures that are uniquely suited, both technically and economically, to the construction of distributed application environments. Unfortunately, despite the growing importance of these standards to a very large community of computer system builders and users, the standards-making process is not widely understood; it has a language of its own, and its metabolism is extremely confusing to those who are not actively involved. These reports are motivated by the belief that better standards - timelier, more relevant, and closer to the state of the art - will result from a more widely informed community of interest.
Communication standards are produced by a large number of domestic and international organizations, most of which have meaningless, unpronounceable names that look like something out of the Dewey Decimal system. As a further complication, the organizations and their relationships to one another change as the standards-making process evolves. The most important telecommunications standards organization, the International Telephone and Telegraph Consultative Committee (CCITT), disbands its study groups every four years, holds a plenary meeting (the 8th CCITT Plenary Assembly was held on October 8-19, 1984), and creates new study groups for the next four-year period. The other major communications standards body, Technical Committee 97 of the International Organization for Standardization (ISO), has just completed a major reorganization of its subcommittees, which particularly affects the groups working on Open Systems Interconnection (OSI) standards. This report contains a new ISO TC97 organization chart, which supercedes the corresponding chart in the first of these reports (CCR 13:1, January, 1983). A new CCITT organization chart will appear in the next issue of CCR.
Summary descriptions of what some of the standards groups are doing, arranged by subject, begin below. Needless to say, there are many other standards activities that for reasons of limited space are not mentioned.
Problems in the design of control procedures for computer networks
Authors: Opderbeck Holger 
Published: October 2004

This paper is one in a series of short papers highlighting research problems in the area of computer communication. Two previous papers have described problems in the design of data communication networks [CHOU 74] and selected research areas in computer communication [KLEI 74a]. In this paper, we will concentrate on problems which arise in the design of control procedures for computer networks. While some of the problems we are going to describe refer explicitly to packet - switched computer communication networks, others apply to packet-switched as well as line-switched systems. We will consider the following six problems:
1. Flow control and routing
2. Design and implementation of efficient protocols
3. Definition of network performance
4. Portability of communications software
5. Distribution of intelligence
6. Process synchronization with unrealiable components
The CCITT studies packet switching as part of public data network development
Authors: Bothner H. 
Published: October 2004

One main body within the UN affiliated International Telecommunications Organisation is the "Comite consultatif international télégraphique et téléphonique" or the CCITT to the whole of the telecommunications world. This grand committee meet in plenary about every four years to adopt recommendations in the areas of tariffs, operations and technical principles, to ensure and improve international telecommunications services between the many networks of all the countries in the world. The committee also decides the questions to be considered in the following study period.
The recommendations of the CCITT has very strong standing internationally, and to a large extent they are being used also as guidelines for national network development. In the field of data transmission the well established cooperation with bodies representing computer users and manufacturers has made it possible to develop widely recognized interface specifications between telecommunications/computing equipment and functions.
Between the plenary meetings of the CCITT the detailed work is being carried out in a number of Study Groups. There is one special group for data transmission techniques over the existing telegraph and telephone networks "SG Special A" (they make all the modem specifications), and one younger one for new digital data transmission networks, the "SG VII". Members of these study groupes are the telecommunications administrations and operating companies ("carriers"), manufacturers of equipment and cooperating international organisations. These groups meet once or twice a year.