bluuebunny/crossref_metadata_2025 huggingface dataset:
COMMERCIAL MAGNETO-RHEOLOGICAL FLUID DEVICES
Authors: Carlson J.D. , Catanzarite D.M. , St. Clair K.A.
Published: October 2004

Controllable magnetorheological (MR) fluid devices have reached the stage where they are in commercial production. Such devices are finding application in a variety of real world situations ranging from active vibration control to aerobic exercise equipment. Examples of several, commercial MR fluid devices are described and the comparative ability of MR and ER fluids to meet the needs of practical devices is discussed.
Finite Element Analysis of Electrorheological Fluids
Authors: Tao R. , Jiang Qi , Sim H.K.
Published: October 2004

The Laplace equation for an infinite chain of dielectric particles in an electrorheological fluid is solved with the finite element analysis (FEA) method. The FEA results reveal that the dipole model gives a good approximation in calculating energy, even if neighbor particles are very close and the mismatch is moderate. However, the dipole model underestimates the pair attractive force when the particles are in or near contact. The conductor model is a good approximation when the two particles are near contact and the mismatch is very big. A formula to calculate the neighbor pair attractive force for the whole range is proposed. The FEA results agree with this formula reasonably well.
STEADY-STATE SOLUTION OF AN ER CLUTCH AT HARMONIC LOAD
Authors: ORAVSKÝ VLADIMÍR , KRČ-JEDINÝ VLADIMÍR
Published: October 2004

A concentric electrorheological clutch (ERC) constituting the central part of a broader system: electro-hydro-aggregate (EHA) with an electrodrive on one side and a loading machine on the other side is considered. Harmonic loading moment is taken into account. Dynamic model of EHA is presented in a dimensionless form and linearized in the vicinity of mean values of the sought steady-state solution. Due to limited extent of the paper further course of solution is described only briefly whereby averaging of variable viscosity of ER fluid is performed. As solution special Bessel, i. e., Kelvin functions and matrix calculus are utilized. Methodology of 3-level analysis is briefly described. Some results of preliminary analysis are presented. Lastly some open problems are pointed out.
STUDIES OF ER FLUIDS FEATURING RODLIKE PARTICLES
Authors: KANU REX C. , SHAW MONTGOMERY T.
Published: October 2004

Chaining of micron-sized polarizable particles in ER fluids is generally accepted to be responsible for the liquid-to-solid transitions on the application of an external electric field. It has been hypothesized that the strength of the particle-particle interactions solely determines the rheological properties of ER fluids. In our work, the particle’s structure has been used to control interactions; for example, we have developed systems featuring rodlike particles. With such particles it should be possible to enhance the dielectric interaction of the particles as well as their mechanical interaction. The main goal of our effort has been to distinguish between these two mechanisms through measurements of the dielectric properties in conjunction with the rheological responses. Based on the experimental evidence thus far gathered, we can state that most, but not all, of the rheological effects are explainable in terms of the dielectric changes in the fluid.
Dynamics of an Electrorheological Valve
Authors: Whittle M. , Atkin R.J. , Bullough W.A.
Published: October 2004

Time dependent solutions to the equations of motion for flow in an electro-rheological valve are developed and discussed in relation to the limiting speed of operation. The fluid is considered to be a homogeneous continuum obeying the Bingham plastic constitutive equation incorporating a yield stress and viscous component. The results show that the speed of response is determined principally by the plastic viscosity and electrode gap irrespective of the yield stress and corroborates earlier work.
COMPARISON OF FREQUENCY CHARACTERISTICS IN A DAMPER USING MAGNETIC FLUID, ER FLUID DISPERSING SMECTITE, AND MIXED ER MAGNETIC FLUID
Authors: FUJITA TOYOHISA , WADA YASUHISA , OBINATA GORO , AKAGAMI YOICHI , NISHIMURA SHINZO , OGASAWARA YUJI
Published: October 2004

This paper presents a new type of damper using electro-rheological (ER) magnetic fluid for improving magnetic fluid damper and ER fluid damper. Silicone oil based magnetic fluid dispersing 10 nm size of magnetite, silicone oil based ER fluid dispersing 2 nm to 50 nm size of smectite and a mixture, that is, ER magnetic fluid have been used in a piston type damper. Dynamic visco-elasticities of these fluids have been measured by considering chain (cluster) formations. Next, frequency characteristics of transmissibility (magnification factor) and phase in damper have been compared with those fluids under magnetic field, electric field and both fields. The Voigt or Maxwell model can be applied in those dampers depending on amplitude. ER magnetic fluid has showed the decrease of amplitude ratios at resonance point and higher frequency at any amplitude under both magnetic and electric fields as low-pass filter.
STATIC AND DYNAMIC LIGHT SCATTERING OF DILUTE MAGNETORHEOLGICAL EMULSIONS
Authors: HAGENBÜCHLE M. , SHEAFFER P. , ZHU Y. , LIU J.
Published: October 2004

The structure formation and dynamics of a dilute, monodisperse ferrofluid emulsion under the influence of an external magnetic field have been investigated using static and dynamic light scattering techniques. In the absence of an external field, the spherical emulsion particles behave as a dilute system of hard spheres where the static light scattering is dominated by the droplet form factor and the dynamic light scattering provides the diffusion coefficient due to their Brownian motion. An applied magnetic field induces a magnetic dipole moment in each droplet. Static light scattering is used to study the time dependence of the structure formation caused by the dipole-dipole interaction as a function of the field strength. The change of the dynamic properties due to chain formation is studied by dynamic light scattering.
THE FREQUENCY DEPENDENCE AND NON-LINEAR DIELECTRIC PROPERTY OF ER FLUID
Authors: LU KUNQUAN , WEN WEIJIA , LI CHENXI
Published: October 2004

The frequency dependence of the shear stress in ac field and the non-linear dielectric property of ER fluid have been studied. We find that the shear stresses of some water-free ER fluids increase monotonously with the frequency and tend to reach saturated values at high frequency. The measurements on KNbO 3/silicone ER fluid show that the shear stresses under 103 Hz frequency a.c. field are several times or even an order larger than that under d.c. field for the same field strength. The studies of non-linear dielectric properties of ER fluids show that the permittivity of ER fluid increases linearly with increasing field strength when the electric field exceeds a threshold value E 1 and tends to a saturated constant beyond a high field strength E 2. Correspondingly the current density follows linear behavior no longer in the region between E 1 and E 2. A model based on the rearrangement of the particles under the electric field. which causes the variation of the dielectric property of the ER fluid, is proposed and the analysis is consistent with the measured results.
PROPERTIES OF ELECTRORHEOLOGICAL FLUIDS CONTAINING SULFONATED POLY(STYRENE-CO-DIVINYLBENZENE) PARTICLES
Authors: ASAKO YOSHINOBU , ONO SATORU , AIZAWA RYUJI , KAWAKAMI TOSHIHIRO
Published: October 2004

Two series of sulfonated poly(styrene-co-divinylbenzene) particles (SSD), different in average particle diameter and in sulfonic acid substitution level were synthesized. The vertical sectional views of the SSD particles showed that the sulfonic acid groups were uniformly distributed all over the SSD particles. The electrorheological behavior of the suspensions of the SSD particles in silicone oil was investigated. Induced shear stress under an electric field increased with the increase of average particle diameter and sulfonic acid substitution level. The sedimentation velocity of the dispersed particles was monotonous with the average particle diameter and the sulfonic acid substitution level. Another series of sulfonated poly(styrene-co-divinylbenzene) particles (SSDH), different in sulfonic acid substitution level, was separately prepared. The vertical sectional views of the SSDH particles showed that the particles had sulfonated surface layer and unsulfonated core. The suspensions of the SSDH particles having the sulfonated layer of not less than 1.4 microns induced similar shear stress at the same electric field strength. The sedimentation velocity of the dispersed particles was lowered with diminishing the thickness of the sulfonated layer.
MR FLUIDS WITH NANO-SIZED MAGNETIC PARTICLES
Authors: Kormann Cl. , Laun H.M. , Richter H.J.
Published: October 2004

Recently magnetorheological fluids with nanosized magnetic ferrite particles have become available. Their composition, rheological and magnetic properties are described. A comparison with conventional MR fluids based on micron-sized particles is given. The yield stress of nano-MR fluids can be increased by a moderate magnetic field (0,2 T) by 4000 Pa. It can be modulated by the magnetic field with a response time of less than 5 ms. Details are given on the long term thermal stability at 150 °C, on flow properties at elevated temperatures and at high shear rates. Design principles for MR fluid actuator design are outlined.
SIMULATIONS OF ELECTRORHEOLOGICAL FLUIDS WITH HYDRODYNAMIC LUBRICATION
Authors: MELROSE J.R. , ITOH S. , BALL R.C.
Published: October 2004

We report preliminary results for 3D simulations of a reduced model of electrorheological (ER) fluids. The hydrodynamic interactions are just squeeze flow lubrication and the electrostatic interactions that of point dipoles. In the low Mason number regime the same layer structure seen in earlier non-hydrodynamic simulations is found.
LIGHT SCATTERING STUDIES OF AN ELECTRORHEOLOGICAL FLUID IN OSCILLATORY SHEAR
Authors: MARTIN JAMES E. , ODINEK JUDY
Published: October 2004

We have conducted a real time, two-dimensional light scattering study of the nonlinear dynamics of field-induced structures in an electrorheological fluid subjected to oscillatory shear. We have developed a kinetic chain model of the observed dynamics by considering the response of a fragmenting/aggregating particle chain to the prevailing hydrodynamic and electrostatic forces. This structural theory is then used to describe the nonlinear rheology of ER fluids.
MODEL OF STRUCTURE AND CONDUCTION IN AN ELECTRORHEOLOGICAL FLUID UNDER FLOW
Authors: See H. , Sakurai R. , Saito T.
Published: October 2004

A theoretical model of moderately concentrated ERF suspensions under shear flow is proposed which explicitly takes into account the effects of conductivity. Under an electric field a layered structure will form between the electrodes, with the solvent flow restricted to a central free-flowing region, and this gives rise to the field-induced viscosity increase. Using this model, the effect on the ERF properties of inhomogeneities of the particle conductivity can also be estimated. It is predicted that the addition of even small amounts of highly conductive particles to an ERF will dramatically reduce the field-induced viscosity increment, a phenomenon that has been observed in recent experiments.
RHEOLOGY OF MAGNETORHEOLOGICAL FLUIDS: MODELS AND MEASUREMENTS
Authors: GINDER J.M. , DAVIS L.C. , ELIE L.D.
Published: October 2004

Numerical and analytical models of magnetorheological fluid phenomena that account explicitly for the effects of magnetic nonlinearity and saturation are described. Finite-element analysis was used to calculate the field distribution in chains of magnetizable particles. The field-dependent stress required to shear the chains was then obtained using the Maxwell stress tensor. Three regimes are identified: at low applied fields, the stress increase quadratically, as expected from linear magnetostatics. In intermediate fields, the contact or polar regions of each particle saturate, reducing the rate of increase of the stress with increasing field. At high fields, the particles saturate completely, and the stress reaches its limiting value. Approximate analytical expressions for the yield stress and shear modulus in these regimes are also derived. The predictions of these models are compared to magnetorheological experiments in the literature and from our laboratory. These models predict successfully the magnitude of the stresses as well as their field dependence. They also suggest that particles comprised of materials with higher saturation magnetizations will exhibit the largest magnetorheological effects.
MAGNETORHEOLOGICAL MATERIALS BASED ON IRON ALLOY PARTICLES
Authors: Margida Anthony J. , Weiss Keith D. , Carlson J. David
Published: October 2004

A magnetorheological material containing iron alloy particles demonstrates magnetorheological strength dependent upon the elements of the alloy and relative concentration of the alloy elements. Selected iron/cobalt alloys demonstrate improved yield strength over traditional carbonyl iron based MR materials when the iron-cobalt alloy has an iron-cobalt ratio ranging from about 30:70 to 95:5. The iron-nickel alloys which have an iron-nickel ratio ranging from about 90:10 to 99:1 maintains superior strength over iron-nickel alloys outside that range.
ELECTRON PARAMAGNETIC RESONANCE DETECTION OF SOLITONS IN TWO-DIMENSIONAL MAGNETS
Authors: ZASPEL C.E. , DRUMHELLER JOHN E.
Published: October 2004

It has previously been assumed that spin waves were the dominant excitations in lower-dimensional magnets. Recently, however, it has been shown that nonlinear excitations or solitons rather than spin waves influence the dynamic thermal quantities such as the spin correlation function which can be investigated experimentally through the electron paramagnetic resonance linewidth. In this review the influence of both spin waves and solitons on the temperature-dependent linewidth in the fluctuation region immediately above the ordering temperature is discussed. It is seen that both excitations result in a theoretical Arrhenius temperature-dependence, (∆H~ exp (E/T) where E=6πJs2 for spin waves and E=4πJs2 for solitons, J is the nearest neighbor exchange constant, and s is the value of the spin. In experiments, quantum (s=1/2) layered copper compounds exhibit the temperature dependence expected from spin waves even though nonlinear excitations have been shown to exist in these systems. On the other hand nearly classical (s=5/2) manganese compounds have the temperature dependence expected from solitons. The calculation of the linewidth from both spin waves and solitons is reviewed and compared with experimental data to show that solitons dominate the dynamics of the layered, nearly classical magnet.
DISCRETE SCALE INVARIANCE IN STOCK MARKETS BEFORE CRASHES
Authors: FEIGENBAUM JAMES A. , FREUND PETER G.O.
Published: October 2004

We propose a picture of stock market crashes as critical points in a system with discrete scale invariance. The critical exponent is then complex, leading to log-periodic fluctuations in stock market indexes. We present “experimental” evidence in favor of this prediction. This picture is in the spirit of the known earthquake-stock market analogy and of recent work on log-periodic fluctuations associated with earthquakes.
From the chair
Authors: Sipior Janice C. , Schatzberg Laurie , Leidner Dorothy , Niederman Fred , Lending Diane
Published: October 2004

Greetings!I am pleased to report that the ACM-SIGMIS CPR (Computer Personnel Research) 2004 Conference held at the Tucson Marriott University Park in Tucson, Arizona, April 22-24, 2004, was a great success! This year's conference was co-sponsored by the Arizona Center for Information Science and Technology (ACIST) and the University of Arizona's MIS Department. Please join me in extending our sincere appreciation to the members of the Conference Committee for all their efforts: Conference Chair, Mohan Tanniru, University of Arizona; Program Chair, Suzanne Weisband, University of Arizona; Conference Treasurer, Laurie Schatzberg, University of New Mexico; Publicity Chair, Sue Brown, Indiana University; and Arrangements Chair: Sherry Thatcher, University of Arizona.The first recipients of the "Magid Igbaria Outstanding Conference Paper of the Year Award" are Dr. Maren Simonsen, University of Bergen, and Dr. Maung Sein, University of Bergen and Agder University College, Norway, for their paper, "Conceptual Frameworks in Practice: Evaluating EU Training Strategy in Organizations." Congratulations to you both!The annual SIGMIS Business Meeting was held by Laurie Schatzberg, SIGMIS Vice Chair, directly after the close of the conference. A report on the improved status of our financial position, due in large part to proceeds from ACM's Digital Library, was presented. Please continue to consider Data Base and the ACM-SIGMIS CPR Conference as an outlet for your research and a source of information.A Preliminary Outcome Report for the CPR 2004 Conference was presented by Mohan Tanniru, CPR 2004 Conference Chair. A Progress Report for the CPR 2005 Conference was given by Mike Gallivan and Eph McLean, both of Georgia State University. Plans for next year's CPR 2005 Conference, to be held in Atlanta, Georgia, are underway. All members are welcome. Please contact Mike Gallivan, mgalliva@gsu.edu, or Eph McLean, emclean@gsu.edu, for more information.Finally, please join me in extending a warm welcome to our new Information Director: Susan Vowels, Washington College, svowels2@washcoll.eduIn response to a call for volunteers sent to the SIGMIS email distribution list (SIGMIS-members@acm.org), we received expressions of interest from eight members. After careful consideration by the SIGMIS Executive Committee, Susan was appointed, mid-term, to this 2 year position (July 2003 to July 2005). She replaces Diane Lending of James Madison University, who has graciously agreed to serve as the next CPR (Computer Personnel Research) Committee Chair. We would like to thank to Diane for her superior service as Information Director. We would like to take this opportunity to thank Fred Niederman of Saint Louis University for his outstanding contributions as the first CPR Committee Chair.As always, we encourage and welcome your suggestions. Please feel free to contact any one of us with your input or ideas. Have a nice summer!
Consumer acceptance of virtual stores
Authors: Chen Lei-da , Gillenson Mark L. , Sherrell Daniel L.
Published: October 2004

Virtual stores provide great efficiency in the retail value chain, and their existence has tremendously paved the way for the diffusion of electronic commerce. Understanding the determinants of consumer acceptance of virtual stores will provide important theoretical contributions to the area of business-to-consumer (B-to-C) electronic commerce and lead to the development of more effective and meaningful strategies for virtual stores. By expanding the Technology Acceptance Model and the Innovation Diffusion Theory, this study aims to provide an integral theoretical paradigm that can successfully support a wide array of technical, business, and consumer issues involved in online retailing. The results from a Web-based survey of 253 online consumers indicate that the proposed theoretical model is able to explain and predict consumer acceptance of virtual stores substantially well. The resulting theoretical model explains a large portion of the factors that lead to a user's behavioral intention to use and actual use of a virtual store. In addition to providing new theoretical grounds for studying the virtual store phenomenon, this article also supplies virtual stores with a number of operative critical success factors to remain competitive in the volatile electronic marketplace.
Independence results in computer science
Authors: Hartmanis J. , Hopcroft J. E.
Published: October 2004

In this note we show that instances of problems which appear naturally in computer science cannot be answered in formalized set theory. We show, for example, that some relativized versions of the famous P = NP problem cannot be answered in formalized set theory, that explicit algorithms can be given whose running time is independent of the axioms of set theory, and that one can exhibit a specific context-free grammar G for which it cannot be proven in set theory that L(G) = Σ* or L(G) ≠ Σ*.
A general method for solving divide-and-conquer recurrences
Authors: Bentley Jon Louis , Haken Dorothea , Saxe James B.
Published: October 2004

The approximate complexity of divide-and-conquer algorithms is often described by recurrence relations of the formT(n) = kT(n/c) + f(n).The only well-defined method currently used for solving such recurrences consists of solution tables for fixed functions f and varying k and c. In this note we describe a unifying method for solving these recurrences that is both general in applicability and easy to apply. This method is appropriate both as a classroom technique and as a tool for practicing algorithm designers.
On the necessity of cryptanalytic exhaustive search
Authors: Hellman Martin E. , Karnin Ehud D. , Reyneri Justin
Published: October 2004

It is shown that the amount of computation required for a general cryptanalytic method is equivalent to an exhaustive search over the key space. In particular, any general time-memory tradeoff must do an exhaustive search as a part of the pre- or post-computation.
On the feasibility of computing discrete logarithms using Adleman's subexponential algorithm
Authors: Herlestam Tore
Published: October 2004

Some public key distribution systems, based on the difficulties in computing logarithms modulo a large prime, have been alleged to be insecure because of a statement that any logarithm modulo a 200 bit prime can be computed within a reasonable time by means of a subexponential algorithm due to Adleman.In this commentary said algorithm is examined from an algebraic and number-theoretical point of view. The scrutiny shows that the algebraic model for the algorithm contains several traps which seem to be hard to circumvent, and also, not least, that the presupposed abundance of so called round numbers will not be at hand in the computationally interesting cases.Hence it is concluded that the algorithm cannot be a serious threat to the mentioned public key distribution systems.
A note on the functional estimation of values of hidden variables
Authors: Findler Nicholas V. , Lo Ron
Published: October 2004

The paper describes an extension of our work on the Generalized Production Rules System. In its original form, it could estimate at a given point of time or space the value of hidden variables---variables that can be measured only intermittently or periodically. In contrast, open variables are readily measurable any time. The system establishes stochastic, causal relations, generalized production rules, between known values of hidden variables and certain mathematical properties of the open variables' behavior. These rules are then used to make the point estimates.We have now provided the system with the additional ability to estimate the functional behavior of the hidden variables. The system can serve as a domain-independent module to a knowledge-based expert system in need of such numerical estimates.
On the general graph embedding problem with applications to circuit layout
Authors: Turner Jonathan S.
Published: October 2004

This paper addresses a class of graph embeding problems in which the object is to map the vertices of one graph to the vertices of another, so that the images of vertices that are adjacent in the source graph are close together in the target graph. An important special case is the bandwidth minimization problem in which the target graph is a simple line graph. In a previous paper, this author showed that for random graphs having bandwidth at most k, a well-known heuristic produces solutions having cost not more than 3k with high probability. This paper ger ralizes these results to the general graph embedding problem. A class of heuristics is described that can be applied to many families of target graphs. Certain aspects of these heuristics depend on properties of the target graphs. These properties are characterized and used to state several metatheorems. Typical of the results is a theorem showing that there exists an efficient heuristic that for random graphs having a cost k embedding in a rectangular grid, will produce an embedding having cost not more than 3k with high probability.
Ada tasking as a tool for ecological modelling
Authors: Murray A. G.
Published: October 2004

Ada [1] has many advantages for writing programs of ecological models. Tasks are the most novel and enable programs to be written in a way that is closer to the structure of such models. As the flows for ecological models are usually unconditional, deadlock of tasks can be detected by simple diagrams. Tasks aid debugging of ecological programs.
Error handling in large, object-based Ada systems
Authors: Kruchten Philippe
Published: October 2004

The purpose of this paper is to show the kind of problems that appear while using a "schoolbook" error-handling strategy based on Ada exceptions in large, object-based systems.' The paper will show that the common solutions used to alleviate those problems are inadequate, and it will suggest two alternative strategies.
Anonymous (special topic)
Authors: Wengelin D. , Carlsson Goethe M. , Asplund L.
Published: October 2004

Using a source code transformation approach to Ada in a distributed environment will give some implementation difficulties. This paper presents an all Ada, portable, solution to the problem of suspending a caller on one node during a call to a remote node. The solution is based on two sets of tasks on each node, making it possible for a caller to hang on an entry during the call. Algorithms are presented in pseudo-Ada.
Protocol conversion—correctness problems
Authors: Lam Simon S
Published: October 2004

Consider the problem of providing a logical channel for message exchange between two user processes in a network environment. When is protocol conversion needed? To answer this question, we first define a model of layered architectures. Specifically, three stepwise refinement rules are given. Any architecture that can be obtained by a sequence of applications of the stepwise refinement rules is said to be well-structured. We show that this class of well-structured architectures has several correctness properties. It is also very general and includes many well-known networking and internetworking architectures in the literature. Logical connectivity in such an architecture is defined recursively. As a result, to determine if a logical channel can be provided between two user processes, it is sufficient to examine peer protocols specified for each level of the architecture's hierarchy of processes one at a time. Thus the original problem reduces to the problem of determining if a set of processes will interoperate.

When protocol conversion is needed to achieve interoperability between processes that implement different protocols, how should it be done? How does one prove that a conversion is correct? What is meant by a correct conversion? We propose the use of projections and image protocols (previously developed by Lam and Shankar for protocol verification [10]) for specifying conversions and for reasoning about the correctness of conversions. Given two processes implementing different protocols P and Q, our objective is to find the largest protocol that is an image protocol of P as well as Q. The correctness of the conversion is a consequence of the correctness properties of image protocols.

There are several open problems. Most importantly, heuristics are used for finding the necessary image protocol for conversion. Although, an image protocol common to both P and Q can always be found, it may not be easy to find one with useful functionality. There are also some implementation and design issues to be addressed, such as: the construction of converters that are transparent and converters that add functionality to an image protocol common to P and Q.
Prediction of transport protocol performance through simulation
Authors: Mills K , Wheatley M , Heatley S
Published: October 2004

A five-layer simulation model of OSI protocols is described and applied to predict transport performance on a local area network (LAN). Emphasis is placed on time-critical applications typical of a small, flexible manufacturing system. The results predict that, with current technology, OSI protocols can provide 1.5 Mbps throughput, one-way delays between 6 and 10 ms, and response times between 15 and 25 ms. The results also indicate that CSMA/CD is a reasonable access method for time-critical applications on small, factory LANS, if loads of less than 40% are anticipated. For loads between 40% and 70%, a token passing access method provides better performance for time-critical applications.
Voice and data performance measurements in L-express net
Authors: Borgonovo F , Cadorin E , Fratta L , Pezze M
Published: October 2004

L-Express is a protocol for Local Area Networks based on a single bus topology. It utilizes a simple and efficient virtual token access scheme which provides ordered and collision-free transmission.

This paper presents results of measurements performed to investigate in details the behavior of the L-Express protocol under different network speeds, configurations and traffic environments. The measurements are obtained using a mix of simulation and field tests on a network prototype. Voice and integration of voice and data are also taken into account.

The results indicate a good behavior (compared with Ethernet) for small size networks (500 m) and Low data rates (10 Mb/s) as well as for Large size networks (5000 m) and high data rates (100 Mb/s).
Conformity analysis for communication protocols
Authors: Liu N , Liu M T
Published: October 2004

In this paper we propose a methodology for conformity analysis of communication protocols. By conformity analysis it is meant to demonstrate that a protocol does indeed provide the service for which it is intended. We specify both a protocol and its service by a CSP (Communicating Sequential Processes) based language. To perform the conformity analysis we develop a transformation system to extract from a CSP process the communication sequences that may arise during its execution, and to express these sequences in terms of behavior expressions in CCS (Calculus of Communicating Systems). By performing algebraic manipulations and the equivalence proof on these expressions, we can show that the external behavior of a protocol conforms to its intended service. A version of the Alternating Bit Protocol is used to demonstrate the feasibility of the methodology.
Local distributed deadlock detection by knot detection
Authors: Cidon I , Jaffe J M
Published: October 2004

A distributed algorithm for the detection of deadlocks in store-and-forward communication networks is presented. At first, we focus on a static environment and develop an efficient knot detection algorithm for general graphs. The knot detection algorithm uses at most Ο(

n
2

+
m
) messages and Ο(
log
(
n
)) bits of memory to detect all deadlocked nodes in the static network. Using the knot detection algorithm as a building block, a deadlock detection algorithm in a dynamic environment is developed. This algorithm has the following properties: It detects all the nodes which cause the deadlock. The algorithm is triggered only when there is a potential for deadlock and only those nodes which are potentially deadlocked perform the algorithm. The algorithm does not affect other processes at the nodes.
Why TCP timers don't work well
Authors: Zhang L
Published: October 2004

Repeated observation of TCP retransmission timer problems stimulated investigation into the roles and limitations of timers. Timers are indispensable tools in building up reliable distributed systems. However, as the experience with the TCP retransmission timer has shown, timers have intrinsic limitations in offering optimal performance. Any timeout based action is a guess based on incomplete information, and as such is bound to be non-optimal. We conclude that, if we aim at high performance, we should use external events as a first line of defense against failures, and depend on timers only in cases where external notification has failed.
Description of a planned federal information processing standard for transport protocol
Authors: Heafner John F. , Blanc Robert P.
Published: October 2004

The National Bureau of Standards has developed service and design specifications for transport and session protocols for use in computer system and network procurements. These protocols reside in layers four and five of the International Organization for Standardization's (ISO) Reference Model for Open Systems Interconnection. This paper describes the services, interfaces, and internal behavior of the transport protocol. The transport (and session) protocol specifications were derived from the most recent developments within ISO on these protocols. Specific features were selected based on the needs of the agencies of the Federal Government within the United States, but they are consistent with the needs of any large organization engaged in the procurement or development of networks of heterogeneous computer systems.
The great debate over telematics and employment
Authors: Rivera Eduardo , Briceño Lilia
Published: October 2004

This paper presents a comprehensive survey of different positions around the problematique of how the Telematics will influence the employment. It is concluded with some comments that open new questions specifically for Mexico.
Local area networks for the automated office - a survey
Authors: Braun Arthur R.
Published: October 2004

This paper looks at the characteristics of the three types of information that can be expected to exist in the Automated Office of the Future:. voice, data and video. Then, it presents the three technologies (or methods), known as Local Area Networks, to support these types of information. The Local Area Networks considered here are: Central Switches, Rings and Buses. Two classes of Central Switches are considered: Circuit and Packet. Furthermore, two classes of Bus structures are also considered: Baseband and Broadband. Finally, this paper discusses the implications of each technology upon supporting each of the three types of information.
Incorporation of service classes into a network architecture
Authors: Perlman Radia
Published: October 2004

This paper defines a service class and describes how a completely general service class structure can be provided by a packet switched network. It describes the difference between a handling directive and a routing metric, and defines a service class as an arbitrary collection of handling directives and routing metrics. It describes what types of distributed routing algorithms make it possible to provide for a completely general service class concept in a network, and describes the special problems to be encountered when providing for a general service class capability in a hierarchical network.
Optimal loop topologies for distributed systems
Authors: Raghavendra C. S. , Gerla M.
Published: October 2004

Double loop network architectures offer higher performance and reliability than single loop networks. In this paper, a double loop network which is optimal among all double loops is described. This network topology consists of a loop in the forward direction connecting all the neighboring nodes, and a backward loop connecting nodes that are separated by a distance @@@@@@@@
N
@@@@, where N is the number of nodes in the network. We show that this network is optimal in terms of hop distance between nodes, delay, throughput, and terminal reliability. The paper includes derivation of closed form expressions for the maximum and average hop distance between nodes, number of distinct routes between two farthest nodes, and throughput. The effect of node and link failures on network performance is also considered.
Isolated word recognition based upon source coding techniques
Authors: Buzo Andrès , Martìnez Horacio , Rivera Carlos , Jazcilevich Aron
Published: October 2004

We describe an application of a recently developed speech compression technique to automatic recognition of isolated words (from a given dictionary). The scheme maps sampled speech, from a given word, into a finite codebook (of the same size as the dictionary) using linear predictive coding (LPC) all-pole models and a minimum distortion or nearest neighbor rule between all samples from the given word and the codewords from the codebook. Standard LPC techniques are used to design the codebook, but the final system requires no on-line LPC analysis.
Bifurcated routing in computer networks
Authors: Lai Wai Sum
Published: October 2004

This paper presents a characterization and a survey of multiple path routing in computer networks. It also develops a routing protocol that achieves load sharing and combines the strengths of both virtual circuit and datagram networks.
Turnover of information technology professionals
Authors: Ang Soon , Slaughter Sandra
Published: October 2004

Retaining information technology (IT) professionals is important for organizations, given the challenges in sourcing for IT talent. Prior research has largely focused on understanding employee turnover from an intra-individual perspective. In this study we examine employee turnover from a structural perspective. We investigate the impact on IT turnover of organizations' Internal Labor Market (ILM) strategies. ILM strategies include human resource rules, practices, and policies including hiring and promotion criteria, job ladders, wage systems and training procedures. We collect data on ILM strategies and turnover rates for eight major IT jobs across forty-one organizations and analyze the data using confirmatory agglomerative hierarchical clustering techniques. Our results show that organizations adopt distinct ILM strategies for different IT jobs, and that these strategies relate to differential turnover rates. Specifically, technically-oriented IT jobs cluster in craft ILM strategies that are associated with higher turnover, whereas managerially-oriented IT jobs cluster in industrial ILM strategies that are associated with lower turnover. Further, depending on their contingencies of goal orientation (not-for-profit versus for-profit), IT focus (IT producer versus user), and information intensity (IT critical versus support), organizations adopt an industrial ILM strategy for their technically-oriented IT jobs to dampen turnover. Not-for-profit and IT user organizations where IT is critical adopt industrial ILM strategies for their technically-oriented IT jobs to attenuate turnover and improve the predictability of their IT workforce. IT producers and IT users where IT plays a supporting role adopt craft ILM strategies that engender higher turnover to remain timely and flexible in IT skills acquisition.
Miscellany
Authors: Kaufman Felix
Published: October 2004

The miscellany column is introducing a new element in this issue. We have asked leading business executive to offer their thoughts on the role of business data processing.In this issue, we are devoting the column to excerpts from the keynote address. "
The Sixties: Prologue to Tomorrow
" presented before the American Bankers Association National Automation Conference in Chicago on May 19, 1969 by Mr. A. R. Zipf, Executive Vice President of Bank of America NT&SA.
A DSS for management of patients with a chronic illness
Authors: Starmer C. Frank , Rosati Robert A.
Published: October 2004

There is uncertainty in the management of an individual with a chronic illness. The uncertainty results from lack of information about groups of similar patients. A feedback model for patient care is presented and its implementation discussed. The model requires characterization of patients at the time of entry into the health-care system, cataloging the methods of management used and assessing the response to treatments by following the patient over long periods of time.With a computer-based data management system, the doctor can select a subgroup of like patients and review their management and their responses. Using the experiences of other patients, the doctor and patient can map out the most appropriate treatment. By following the patient over time, his treatment response can be compared with those in the subgroup. If the responses are not equivalent, the subgroup definition can be modified and another treatment selected. An example of the use of this strategy in determining time of discharge for patients on a coronary care unit is presented.
The MIS area
Authors: Dickson G. W. , Benbasat Izak , King William R.
Published: October 2004

Management Information Systems has evolved as an area in which teaching and research is common. In order to consolidate advances made to date in this area and to meet new and significant challenges, a number of problems must be overcome. This paper identifies and discusses the problems, suggests methods for their solution, and concludes by looking toward future opportunities for the area.
Contributions of the management sciences to the evolution of management information systems
Authors: Kendall Kenneth E. , Kriebel Charles H.
Published: October 2004

The "management sciences" concern disciplines that identify, extend, or unify scientific knowledge pertaining to the process and substance of management. The field of management science is often closely allied with the area called operations research through common analytical methods and models. The application and implementation of management science recognizes well the behavioral and economic realities of management practice in organizations. During the past twenty-five years, the management sciences and management's use of information systems technology have evolved together. In this survey we highlight three aspects of this mutual evolution: first, as a basis for enunciating and understanding issues involved in theory and practice; second, as providing tools and techniques to solve managerial and technical problems related to MIS design and development; and third, as a component of "MIS technology" available for application and use.
MIS and the behavioral sciences
Authors: Bariff Martin L. , Ginzberg Michael J.
Published: October 2004

Many of the questions of concern to information system (IS) researchers and practitioners are, in essence, behavioral questions. Behavioral considerations in the design and implementation of information systems and in the management of IS professionals are crucial to the successful development and delivery of quality services to users. Implementation of IS may provide a beneficial means to facilitate changes in task design, organizational structure, and social relations. Guidance for interpreting past MIS behavioral research and suggestions for future studies are provided by a proposed research framework. The importance of adopting behavioral science research standards, e.g., theory-based research questions and appropriate methodology, is stressed.
Economics and management information systems
Authors: Kriebel Charles H. , Moore Jeffrey H.
Published: October 2004

Without exaggeration, the basic challenge of management is economics: how to choose to employ scarce productive resources to accomplish limited objectives effectively. It is well recognized today, and increasingly so in post-industrial societies, that information, broadly defined, is a strategic economic resource that must be managed if it is to be productive. A comprehensive literature has developed in the discipline of economics which concerns information, information systems, and information-related phenomena of import to management and the development of management information systems (MIS). Although this literature is vast, this overview attempts to relate some of this work to MIS and MIS research.We highlight results in three general areas: (1) those which concern the effect of information upon economic markets external to the firm, (2) those which concern issues of information and its relation to decision making and the internal organization of the firm, and (3) those which concern questions of allocation and control of information resources within the firm. In particular, attention will be directed to interpretation of the major results related to the effect of information upon markets and upon individual decision making, team theory, agency theory, decomposition theory, resource allocation and pricing, incentives, and information evaluation.
SOS
Authors: Bracchi G. , Pernici B.
Published: October 2004

Analysis and design of office information systems require the development of conceptual models for representing the different aspects of office work in an integrated way, independently of implementation details. This paper discusses the requirements for office conceptual models, showing their main distinguishing features with respect to conventional information systems models. On the basis of these requirements, the design criteria and the main features of the Semantic Office System model (SOS) are illustrated. Modeling of static, dynamic and evolutive aspects of the office work in SOS is discussed.
A method for speeding up text retrieval
Authors: Larson Per-Ake
Published: October 2004

A simple method for speeding up the term detection phase of retrieval from a full-text document database is presented. The method makes use of a surrogate database, in which a document is represented as a sequence of hash signatures. Each signature represents a term occurring in the original document. The size of the surrogate database is expected to be only 5-10% of the original database. The major part of the work involved in term detection can be done utilizing this smaller database. It can either be scanned or inverted and used as an index. The term detection phase is speeded up significantly at a cost of increased processing when filing a document.
Design of a document filing and retrieval system
Authors: King Richard P. , Korth Henry K. , Willner Barry E.
Published: October 2004

This paper describes a scheme for secondary-key-based data retrieval. The scheme is designed for a document filing and retrieval system in which documents are filed under a large number of keys, but queries specify only a few keys. As this work is based on microcomputers with virtual memory, the primary objective was minimization of page faults, with processing speed and simplicity of code also of critical importance. Initial experiments with the scheme indicate good performance with respect to both processing time and paging.
A framework of reference for database design
Authors: Agosti Maristella , Johnson Roger G.
Published: October 2004

This work introduces a framework of reference for database design.Database (DB) design is presented as a part of information system (IS) design, because the DB design process is concerned with the construction of a database as a subsystem of an IS. Then the DB design process is related to the general system development process and all existing connections are stated.The actions which are necessary to implement a database are divided in two categories: data system design and management design. The utility of a reference model for the data system design is shown.