bluuebunny/crossref_metadata_2025 huggingface dataset:
GEOMETRIC KNOT SPACES AND POLYGONAL ISOTOPY
Authors: CALVO JORGE ALBERTO
Published: July 2002

The space of n-sided polygons embedded in three-space consists of a smooth manifold in which points correspond to piecewise linear or "geometric" knots, while paths correspond to isotopies which preserve the geometric structure of these knots. The topology of these spaces for the case n=6 and n=7 is described. In both of these cases, each knot space consists of five components,but contains only three (when n=6) or four (when n=7) topological knot types. Therefore "geometric knot equivalence" is strictly stronger than topological equivalence. This point is demonstrated by the hexagonal trefoils and heptagonal figure-eight knots, which, unlike their topological counterparts, are not reversible. Extending these results to the cases n≥8 will also be discussed.
QUANTUM NONDEMOLITION MEASUREMENTS OF A PARTICLE IN ELECTRIC AND GRAVITATIONAL FIELDS
Authors: CAMACHO A. , CAMACHO-GALVÁN A.
Published: July 2002

In this work we obtain a nondemolition variable for the case in which a charged particle moves in the electric and gravitational fields of a spherical body. Afterwards we consider the continuous monitoring of this nondemolition parameter, and calculate, along the ideas of the so called restricted path integral formalism, the corresponding propagator. Using these results the probabilities associated with the possible measurement outputs are evaluated. The limit of our results, as the resolution of the measuring device goes to zero, is analyzed, and the dependence of the corresponding propagator upon the strength of the electric and gravitational fields is commented. The role that mass plays in the corresponding results, and its possible connection with the equivalence principle at quantum level, are studied.
THE RÖSSLER EQUATIONS REVISITED IN TERMS OF FEEDBACK CIRCUITS
Authors: THOMAS R.
Published: July 2002

We would like to show that complex dynamics can be deciphered and at least partly understood in terms of its underlying logical structure, more specifically in terms of the feedback circuits built in the differential equations. This approach has permitted to build a number of new three- and four-variable systems displaying chaotic dynamics.

Starting from the well-known Rössler equations for deterministic chaos, one asks how systems with the same types of steady states can be synthesized ab initio from appropriate feedback circuits (= appropriate logical structure). It is found that, granted an appropriate logical structure, the existence of a domain of chaotic dynamics is remarkably robust towards changes in the nature of the nonlinearity used, and towards those sign changes which respect the nature (positive vs negative) of the feedback circuits. Using logical arguments, it was also easy to find related systems with a single steady state. A variety of 3- and 4-d systems based on other combinations of feedback circuits and generating chaotic dynamics are described.

The aim of this work is to contribute to a better understanding of the respective roles of feedback circuits and nonlinearity — both essential — in so-called "non trivial behavior", including deterministic chaos. Special emphasis is put on the interest of using the Jacobian matrix and its by-products (characteristic equation, eigenvalues, …) not only close to steady states (where linear stability analysis can be performed) but also elsewhere in phase space, where precious indications about the global behavior can be collected.
STRUCTURE OF A SINGLE ATOMIC LAYER OF NICKEL DEPOSITED ON THE Pt(111) SURFACE DETERMINED BY LOW ENERGY ELECTRON DIFFRACTION
Authors: ATREI A. , BARDI U. , ZANAZZI E. , ROVIDA G. , SAMBI M. , GRANOZZI G.
Published: July 2002

The structure of ultrathin films of Ni deposited at room temperature on the Pt (111) surface has been determined by low energy electron diffraction (LEED) intensity analysis. The first monolayer of Ni grows pseudomorphically on Pt (111) despite the 11% mismatch between the lattice parameters of nickel and platinum. The results of the analysis also show that the Ni atoms occupy face-centered-cubic sites on the substrate surface. These results in part confirm previous data obtained by X-ray photoelectron diffraction, but also provide more reliable data on the site assignment.
GROWTH OF OXIDE LAYER ON GERMANIUM (011) SUBSTRATE UNDER DRY AND WET ATMOSPHERES
Authors: TABET N. , AL-SADAH J. , SALIM M.
Published: July 2002

X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the oxidation of (011) Ge substrates. The sample surfaces were CP4-etched, then annealed in situ, at different temperatures, for various durations. Dry and wet atmospheres were used. The oxidation rate during the early stage was increased by the presence of moisture in the atmosphere. A simple model was used to define and determine an apparent thickness of the oxide film from XPS measurements. The time dependence of the apparent thickness is consistent with a partial coverage of the surface by oxide islands. The growth kinetics of the oxide islands obeys a nearly cubic law.
DUPUYTREN's DISEASE OF THE WRIST
Authors: Dalton P. A. , Chamberlain S. T. , Stabler D.
Published: July 2002

The authors present the case of a 47-year-old female who presents with bilateral Dupuytren's disease of the wrist. To date, three English language papers reporting on the occurrence of Dupuytren's disease at the wrist have been presented. These reports represent cases in males with unilateral involvement of their wrists where there has been primary Dupuytren's disease of the palm apparently spreading to the wrist in continuity. Our case demonstrates isolated bilateral Dupuytren's disease of the wrist in a female.

The authors feel that this clinical presentation is rare and that consideration should be given to the diagnosis of Dupuytren's disease when there is a painful lesion of the soft tissues adjacent to the wrist. The presence of bilateral lesions at the wrist should further heighten the suspicion of Dupuytren's disease even in the absence of associated disease in the palm or fingers. A discussion of the previous reports is included.
A FORMALISM FOR CONTEXT MEDIATION BASED ON FEATURE LOGIC
Authors: MOTT PETER , ROBERTS STUART
Published: July 2002

This paper describes a formalism for context mediation based on Feature Logic. The formalism enables a distinction to be drawn between integrity and translational aspects of mediation. It is independent of the relational model, though easily used within it. The formalism makes precise the concept of "context" and provides a framework for mediation between disparate data sources.
TREE METHOD FOR OPTION PRICING UNDER STOCHASTIC VARIANCE
Authors: ŠESTOVIĆ DRAGAN
Published: July 2002

We develop a recombining tree method for pricing of options by using a general two-factor stochastic-variance (SV) diffusion model for asset price dynamics. We show that it is possible to construct a riskless hedge by including additional short-term options in the hedging portfolio. This procedure gives us Partial Differential Equation (PDE) that can be solved by using standard numerical techniques giving us a unique option's price. We show that the option's price does not depend on the long run volatility forecast but only on the parameters of the model, which are related to the volatility of variance. We show one particular transformation of PDE to the Finite Difference Equation (FDE) that leads to the three-dimensional lattice method similar to the standard binomial-tree method. Our tree grows in the price-variance space and similarly to the binomial-tree, the coefficients of the FDE can be interpreted as risk neutral probabilities for jumping between the tree nodes. By investigating an error accumulation in the tree we found the stability criterion and the method that can be applied in order to achieve a stabile procedure. Our option pricing method can be used for European and American options and various payoffs. Since the procedure converges quickly and can be easily implemented, we believe that it could be useful for practitioners. The SV model we used here was shown earlier to be a diffusion limit of various GARCH-type models giving the possibility of using parameters obtained in the discrete-time GARCH framework as an input for our option pricing method.
EXPERIMENTAL INVESTIGATION OF THE 1/f AMPLITUDE NOISE OF VERTICAL-CAVITY SURFACE-EMITTING LASERS
Authors: SIGNORET P. , BELLEVILLE G. , ORSAL B.
Published: July 2002

The low and medium frequency - 1 Hz ≤ f ≤ 100 kHz - amplitude noise characteristics of 840 nm proton-implanted VCSELs (Vertical Cavity Surface Emitting Lasers) have been investigated. Experiments clearly show that the DBR (Distributed Bragg Reflector) structure represents the main electrical noise source of VCSELs. Furthermore, the electrical noise is somehow linked to the optical noise when the laser shows a "disturbed" optical spectrum with competition between very close modes.
AN APPROACH FOR THE CORRELATION OF EMG SIGNALS AND THE RECTIFICATION OF PTB SOCKETS
Authors: ABU OSMAN N. A. , WONG S. S. , OMAR Z.
Published: July 2002

Prosthesis is often used to restore the appearance and functional mobility to individuals following limb amputatio n. The purpose of this study is to investigate the correlation between the electromyogram (EMG) signals with the rectification of patellar tendon bearing (PTB) socket. Six PTB sockets are manufactured with different compression depths at the patellar tendon region. Experiments for the subject are carried out to obtain the EMG signals using EMG telemetry system. From this study, it is found that there exists some kinds of pattern as the depths of PTB rectification is changed. As the PTB rectification depth is increased, the EMG activity rises generally yet in an N pattern for the quadriceps group for both left and right legs of the amputee. The results of this case study will lead to an appropriate range of rectification depths for prosthetists in the manufacturing of PTB sockets, and perhaps the identification of the most suitable depth for optimum transtibial amputee ambulation.
LEARNING DELAYED RESPONSE TASKS THROUGH UNSUPERVISED EVENT EXTRACTION
Authors: LINÅKER FREDRIK , JACOBSSON HENRIK
Published: July 2002

We show how event extraction can be used for handling delayed response tasks with arbitrary delay periods between the stimulus and the cue for response. We use a simple recurrent network for solving the task. Our approach is based on a number of information processing levels, where the lowest level works on raw time-step based sensory data. This data is classified using an unsupervised clustering mechanism. The second level works on this classified data, but still on the individual time-step basis. An event extraction mechanism detects and signals transitions between classes; this forms the basis for the third level. As this level only is updated when events occur, it is independent of the time-scale of the lower level interaction. We also sketch how an event filtering mechanism could be constructed which discards irrelevant data from the event stream. Such a mechanism would output a fourth level representation which could be used for delayed response tasks where irrelevant, or distracting, events could occur during the delay.
ON THE CO-EVOLUTION OF EVOLVING EXPRESSIONS
Authors: GREENFIELD GARY R.
Published: July 2002

Perhaps the best known example of user-guided evolution is furnished by evolving expressions, an image generation technique first introduced by Sims. In this version of artificial evolution, images are evolved for aesthetic purposes, hence any fitness measure used must be based on aesthetics. We consider the problem of guiding image evolution autonomously on the basis of computational, as opposed to user-assigned, aesthetic fitness. Due to the difficulty of formulating an absolute criterion for aesthetic fitness, we adopt a coevolutionary approach, relying on hosts and parasites to establish relative criteria for aesthetic fitness. To sustain the coevolutionary arms race, we allow coevolution to proceed in stages. This permits appropriate fitness levels to be maintained within the parasite populations we use to infect host image populations. Using staged coevolution produces two beneficial results: (1) longer survival times for subpopulations of host images, and (2) stable phenotypic lineages for host images.
Text categorization for multiple users based on semantic features from a machine-readable dictionary
Authors: Liddy Elizabeth D. , Paik Woojin , Yu Edmund S.
Published: July 2002

The text categorization module described here provides a front-end filtering function for the larger DR-LINK text retrieval system [Liddy and Myaeing 1993]. The model evaluates a large incoming stream of documents to determine which documents are sufficiently similar to a profile at the broad subject level to warrant more refined representation and matching. To accomplish this task, each substantive word in a text is first categorized using a feature set based on the semantic Subject Field Codes (SFCs) assigned to individual word senses in a machine-readable dictionary. When tested on 50 user profiles and 550 megabytes of documents, results indicate that the feature set that is the basis of the text categorization module and the algorithm that establishes the boundary of categories of potentially relevant documents accomplish their tasks with a high level of performance.

This means that the category of potentially relevant documents for most profiles would contain at least 80% of all documents later determined to be relevant to the profile. The number of documents in this set would be uniquely determined by the system's category-boundary predictor, and this set is likely to contain less than 5% of the incoming stream of documents.
To take arms against a sea of email
Authors: Arensburger Andrew , Rosenfeld Azriel
Published: July 2002

The rapid growth of the Internet means there is more email traffic now than ever before, and there will be still more in years to come. There was a time when only hard-core hackers had to deal with significant amounts of email. As email becomes a standard medium of communication, and more and more nonprogrammers join mailing lists, an increasing number of people find themselves receiving large amounts of email and must cope with it.
Strong deviations from randomness in
m
-sequences based on trinomials
Authors: Matsumoto Makoto , Kurita Yoshiharu
Published: July 2002

The fixed vector of any
m
-sequence based on a trinomial is explicitly obtained. Local nonrandomness around the fixed vector is analyzed through model-construction and experiments. We conclude that the initial vector near the fixed vector should be avoided.
Avoiding Cartesian products for multiple joins
Authors: Morishita Shinichi
Published: July 2002

Computing the natural join of a set of relations is an important operation in relational database systems. The ordering of joins determines to a large extent the computation time of the join. Since the number of possible orderings could be very large, query optimizers first reduce the search space by using various heuristics and then try to select an optimal ordering of joins. Avoiding Cartesian products is a common heuristic for reducing the search space, but it cannot guarantee optimal ordering in its search space, because the cheapest Cartesian-product-free (CPF for short) ordering could be significantly worse than an optimal non-CPF ordering by a factor of an arbitrarily large number. In this paper, we use
programs
consisting of joins, semijoins, and projections for computing the join of some relations, and we introduce a novel algorithm that derives programs from CPF orderings of joins. We show that there exists a CPF ordering from which our algorithm derives a program whose cost is within a constant factor of the cost of an optimal ordering. Thus, our result demonstrates the effectiveness of avoiding Cartesian products as a heuristic for restricting the search space of orderings of joins.
The bisector surface of rational space curves
Authors: Elber Gershon , Kim Myung-So
Published: July 2002

Given a point and a rational curve in the plane, their bisector curve is rational [Farouki and Johnston 1994a]. However, in general, the bisector of two rational curves in the plane is not rational [Farouki and Johnstone 1994b]. Given a point and a rational
space
curve, this art icle shows that the bisector surface is a rational ruled surface. Moreover, given two rational space curves, we show that the bisector surface is rational (except for the degenerate case in which the two curves are coplanar).
Frame memory
Authors: March Salvatore T. , Severance Dennis G. , Wilens Michael
Published: July 2002

Frame memory is a virtual view of secondary storage that can be implemented with reasonable overhead to support database record storage and accessing requirements. Frame memory is designed so that its operating characteristics can be easily manipulated by either designers or design algorithms, while performance effects of such changes can be accurately predicted. Automated design procedures exist to generate and evaluate alternative database designs built upon frame memory, and the existence of these procedures establishes frames as an attractive memory management architecture for future database management systems.
Linear queries in statistical databases
Authors: Schwartz M. D. , Denning D. E. , Denning P. J.
Published: July 2002

A database is compromised if a user can determine the data elements associated with keys which he did not know previously. If it is possible, compromise can be achieved by posing a finite set of queries over sets of data elements and employing initial information to solve the resulting system of equations. Assuming the allowable queries are linear, that is, weighted sums of data elements, we show how compromise can be achieved and we characterize the maximal initial information permitted of a user in a secure system. When compromise is possible, the initial information and the number of queries required to achieve it is surprisingly small.
On the Syntax of Algorithmic Languages
Authors: Gilbert Philip
Published: July 2002

The
analytic grammar
(a model which provides a rigorous description of syntactic analysis) is presented, and some of its fundamental properties are shown. Various submodels are discussed and equivalences among these are noted.

An analytic grammar incorporates a set
P
of syntactic productions, and also a
scan
@@@@. At each successive “rewriting” in the analysis of a string
x
, @@@@ computes a subset of productions applicable to
x
(i.e., which may be used to “rewrite”
x
) from the set of productions which are potentially applicable to
x
. Thus each scan determines a class of grammars.

It is shown that all
analytic languages
are recursive, and conversely, all recursive sets are analytic languages. All phrase structure grammars are analytic grammars. A simple sufficient condition is shown under which an analytic grammar provides unique analyses for all strings.

Particularly relevant to syntactic analysis of
algorithmic languages
(i.e., languages which are used to specify computing algorithms) are the “leftmost” scans, each of which chooses a certain “leftmost” production. Conditions which provide equivalences among these scans are noted.
Models of Computations and Systems—Evaluation of Vertex Probabilities in Graph Models of Computations
Authors: Martin David , Estrin Gerald
Published: July 2002

This paper concerns itself with the modeling of computations and systems and the generation of a priori estimates of expected computation time for given problems on given processing systems. In particular, methods are discussed for determining the probabilities of reaching vertices in a graph model of computations.
Experiments With a Multipurpose, Theorem-Proving Heuristic Program
Authors: Slagle James R. , Bursky Philip
Published: July 2002

The heuristic program discussed searches for a constructive proof or disproof of a given proposition. It uses a search procedure which efficiently selects the seemingly best proposition to work on next. This program is multipurpose in that the domains it can handle are varied.

As an initial experiment, the program was given the task of searching for proofs and disproofs of propositions about kalah end games. Kalah is a two-person game. In another experiment the program, after some modifications,
played
the game of kalah. This program was compared with another tree-searching procedure, the Alpha-Beta minimax procedure; the results have been encouraging since the program is fast and efficient. Its greatest usefulness is in solving large problems. It is hoped that this program has added one more step toward the goal of eventually obtaining computer programs which can solve intellectually difficult problems.
A Combinatorial Problem Related to Interleaved Memory Systems
Authors: Burnett G. J. , Coffman E. G.
Published: July 2002

A combinatorial problem arising from the analysis of a model of interleaved memory systems is studied. The performance measure whose calculation defines this problem is based on the distribution of the number of modules in operation during a memory cycle, assuming saturated demand and an arbitrary but fixed number of modules.

In general terms the problem is as follows. Suppose we have a Markov chain of
n
states numbered 0, 1, ···,
n
- 1. For each
i
assume that the one-step transition probability from state
i
to state (
i
+ 1) mod
n
is given by the parameter
α
and from state
i
to any other state is
β
= (1 -
α
)/(
n
- 1). Given an initial state, the problem is to find the expected number of states through which the system passes before returning to a state previously entered. The principal result of the paper is a recursive procedure for computing this expected number of states. The complexity of the procedure is seen to be small enough to enable practical numerical studies of interleaved memory systems.
A Generalized Multi-Entrance Time-Sharing Priority Queue
Authors: Babad Jair M.
Published: July 2002

A generalized multi-entrance and multipriority M/G/1
time-sharing system is dealt with. The system maintains many
separate queues, each identified by two integers, the priority
level and the entry level The arrival process of users is a
homogenous Poisson process, while service requirements are
identically distributed and have a finite second moment. Upon
arrival a user joins one of the levels, through the entry queue of
this level. In the
(n, k)
-th queue, where
n
is the
priority level and
k
is the entry level, a user is eligible
to a (finite or infinite) quantum of service. If the service
requirements of the user are satisfied during the quantum, the user
departs, and otherwise he is trans- ferred to the end of the
(n
+ 1, k)
-th queue for additional service. When a quantum of
service is completed, the highest priority nonempty level is chosen
to be served next; within this level the queues are scanned
according to the priority of their entry level, and the user at the
head of the highest priority nonempty queue is chosen to be served.
In such a priority discipline, preferred users always get an
improved service, though the service of all users is degraded in
proportion to their service requirements. Expected flow times and
expected number of waiting users are derived and then specialized
to the head-of-the-line M/G/1 priority discipline (in which quanta
have infinite length and service is uninterrupted) and to the
FB
n
time-sharing system. Finally, the generalized
multientrance and multipriority time-sharing discipline is
(numerically) compared with several other time-sharing systems.
Investigation of a new analytical method for numerical derivative evaluation
Authors: Wilkins R. D.
Published: July 2002

A recently proposed analytical approach to numerical derivative evaluation is discussed. The technique is shown to be both accurate and easy to apply, though certain indicated modifications are required. Its use should greatly facilitate the writing and debugging of programs requiring derivatives of highly complex functions.
Compact representation of contour plots for phone line transmission
Authors: Adams John , Gary John
Published: July 2002

Methods for the compact representation of contour plots are described and tested. These are intended to reduce the cost of transmitting contour plots over phone lines. We feel some of these methods could be used to transmit contour plots over voice grade phone lines.
A general purpose data entry program
Authors: Jacky Jonathan P. , Kalet Ira J.
Published: July 2002

Simulations constitute an important family of computer applications in science and engineering. To perform each simulation run, it is usually necessary to provide extensive data specifying the parameters of the simulation as well as data which support the calculation models involved. We have designed a program and a file structure that provides a method for convenient data entry, and creates and edits data files according to specifications contained in a separate file that serves as a template. By providing different templates, the same program can be made to serve numerous applications. The structure of the data files allows a degree of flexibility difficult to achieve using conventional database systems.
Pass-algorithms
Authors: Haskett James A.
Published: July 2002

A superset of the secondary passwords technique, pass-algorithms provide enormous flexibility and ease of implementation and represent an attractive alternative to more costly systems security features and equipment. The method validates users who demonstrate knowledge of a secret algorithm rather than a password.
New sufficient optimality conditions for integer programming and their application
Authors: Fleisher J. M. , Meyer R. R.
Published: July 2002

The purpose of this report is to present a new class of sufficient optimality conditions for pure and mixed integer programming problems. Some of the sets of sufficient conditions presented can be thought of as generalizations of optimality conditions based on primal-dual complementarity in linear programming. These sufficient conditions are particularly useful for the construction of difficult integer programming problems with known optimal solutions. These problems may then be used to test and/or “benchmark” integer programming codes.
The programmer's workbench—a machine for software development
Authors: Ivie Evan L.
Published: July 2002

On almost all software development projects the assumption is made that the program development function will be done on the same machine on which the eventual system will run. It is only when this production machine is unavailable or when its programming environment is totally inadequate that alternatives are considered. In this paper it is suggested that there are many other situations where it would be advantageous to separate the program development and maintenance function onto a specialized computer which is dedicated to that purpose. Such a computer is here called a Programmer's Workbench. The four basic sections of the paper introduce the subject, outline the general concept, discuss areas where such an approach may prove beneficial, and describe an operational system utilizing this concept.
Professionalism in the computing field
Authors: Finerman Aaron
Published: July 2002

The term professional means different things to different people; nevertheless, there are certain general technical and social standards normally associated with a professional. Further, the term is more generally applied to the practitioner rather than to the researcher. But within the rather broad definition specified, the computing practitioner is, as yet, not regarded as a professional.

Each of the four types of institutions—academic, industry, government, and the professional society—that educate, employ, regulate, and mold the practitioner contributes to the “nonprofessional” status of the computing practitioner. The roles of these institutions are examined, various shortcomings are noted, and recommended changes are suggested.

In the last analysis, professional status is not bestowed; it is earned. However, universities and industry, specifically, can make certain improvements to help the computing practitioner achieve professional status.
Algorithm 489: the algorithm SELECT—for finding the
i
th smallest of
n
elements [M1]
Authors: Floyd Robert W. , Rivest Ronald L.
Published: July 2002

SELECT
will rearrange the values of array segment
X
[
L
:
R
] so that
X
[
K
] (for some given
K
;
L
≤
K
≤
R
) will contain the (
K
-
L
+1)-th smallest value,
L
≤
I
≤
K
will imply
X
[
I
] ≤
X
[
K
], and
K
≤
I
≤
R
will imply
X
[
I
] ≥
X
[
K
. While
SELECT
is thus functionally equivalent to Hoare's algorithm
FIND
[1], it is significantly faster on the average due to the effective use of sampling to determine the element
T
about which to partition
X
. The average time over 25 trials required by
SELECT
and
FIND
to determine the median of
n
elements was found experimentally to be:
n
500 1000 5000 10000
SELECT
89 ms. 141 ms. 493 ms. 877 ms.
FIND
104 ms. 197 ms. 1029 ms. 1964 ms. The arbitrary constants 600, .5, and .5 appearing in the algorithm minimize execution time on the particular machine used.
SELECT
has been shown to run in time asymptotically proportional to
N
+ min (
I
,
N
-
I
), where
N
=
L
-
R
+ 1 and
I
=
K
-
L
+ 1. A lower bound on the running time within 9 percent of this value has also been proved [2]. Sites [3] has proved
SELECT
terminates.
On Lion's counter example for Gotlieb's method for the construction of school timetables
Authors: Smith Graham , Sefton Ian M.
Published: July 2002

The timetable problem is an essentially discrete problem. Although the discrete problem may have no feasible solution, there may exist a solution to the equivalent continuous problem. An example, is given, for which the nondiscrete solution can be interpreted as a set of timetables, differing from week to week, which together satisfy the long-term requirements of the timetable problem.
Supporting large-scale distributed simulation using HLA
Authors: Lu Tainchi , Lee Chungnan , Hsia Wenyang , Lin Mingtang
Published: July 2002

This article describes the design of a Web-based environment to support large-scale distributed simulation using Java and IEEE standard P1516 high level architecture (HLA) framework and rules. Based on the run-time infrastructure (RTI) services within the HLA and Java application programmer's interfaces (APIs) of the RTI, the proposed HLA-based environment provides an architectural foundation to enhance interactivity, portability, and interoperability for Web-based simulations. In addition, the proposed architectural design not only provides a client/server mechanism for simulation on the Web, but also supports a distributed federation execution over the network. A 3-level control mechanism (3LCM) was implemented to HLA-based middleware federateServer, in order to adaptively maintain information consistency and minimize message traffic for distributing information among client hosts and the federateServers. A dynamic filtering strategy (DFS), associated with the data distribution management (DDM) in the HLA RTI, is proposed to minimize false positive updates and enhance the filtering efficiency of subscription regions within an HLA federation. To verify the feasibility of this prototype, a distributed discrete event simulation application in Java was developed and performance of the proposed modeling design and Java RMI's distributed object model presented. From the experimental results, we show that the proposed environment based on HLA using 3LCM and DFS is workable and practical for supporting a large-scale distributed simulation.
Gauss harmonic interpolation formulas
Authors: Stroud A. H.
Published: July 2002

Let
R
be an open, bounded, simply connected region in the (
x,y
)-plane and let (
x
*
,
y
*
) be a point in
R
. Assuming
R
is starlike with respect to (
x
*
,
y
*
), we discuss a method for computing Gauss harmonic interpolation formulas for
R
and the point (
x
*
,
y
*
). Such formulas approximate a harmonic function at (
x
*
,
y
*
) in terms of a linear combination of its values at certain selected points on the boundary of
R
. Such formulas are useful for approximating the solution of the Dirichlet problem for
R
.
A Boolean matrix method for the computation of linear precedence functions
Authors: Martin David F.
Published: July 2002

A modified version of Bell's Boolean matrix method for the computation of linear precedence functions associated with a conflict-free matrix of precedence relations is given. This algorithm not only detects when the precedence functions do not exist, but also provides an indication of why they do not exist, so that corrective action can be taken if possible. Necessary and sufficient conditions for the existence of precedence functions are given. The use of Boolean matrices to prove the existence of precedence functions associated with classes of conflict-free grammars is illustrated through an example.
A comparison of floating point summation methods
Authors: Gregory James
Published: July 2002

In the June 1970 issue of Communications, Linz [1] proposed a method of pairwise summing of numbers to reduce accumulated roundoff error. Linz compared his method with only a simple recursive summation. The Linz method should have also been compared with a method published in the January 1965 issue by Kahan [2], which is more accurate.

This note compares the schemes by Linz and Kahan with the straight recursive summation. Comparisons of accuracy, speed and storage were carried out on an IBM 360/75 with various compiler optimization levels. (Linz' restriction to a binary exponent is not essential to his method.)
An analytic model of the HASP execution task monitor
Authors: Strauss J. C.
Published: July 2002

The HASP Execution Task Monitor periodically rearranges the OS/360 dispatching chain to give tasks preemptive execution priority in inverse order to that of their cpu utilization history. The effect is to keep the I/O bound tasks active and to prevent cpu bound tasks from locking out other tasks. This paper develops a simple model of the Execution Task Monitor and employs it to study the effectiveness of the monitor in improving system performance. A modified strategy for monitor control is investigated for the case of task execution in a memory heirarchy of varying speeds.
A queuing model of a multiprogrammed computer with a two-level storage system
Authors: Shedler G. S.
Published: July 2002

The results are presented of an analysis of a probabilistic model of a multiprogrammed computer system with a two-level storage system in which there is sequential dependency of accesses between the devices. Expressions are obtained for the long-run probability that both the CPU and each of the storage devices are busy. Some numerical results are given which quantify the gains in CPU utilization obtainable by multiprogramming in the presence of this type of storage system.
Variable-precision exponentiation
Authors: Richman P. L.
Published: July 2002

A previous paper presented an efficient algorithm, called the Recomputation Algorithm, for evaluating a rational expression to within any desired tolerance on a computer which performs variable-precision arithmetic operations. The Recomputation Algorithm can be applied to expressions involving any variable-precision operations having
O
(10

-
p

+ ∑ |
ε

i

|) error bounds, where
p
denotes the operation's precision and
ε

i

denotes the error in the operation's
i
th argument.

This paper presents an efficient variable-precision exponential operation with an error bound of the above order. Other operations, such as log, sin, and cos, which have simple series expansions, can be handled similarly.
An interactive computer system using graphical flowchart input
Authors: Robbins M. F. , Beyer J. D.
Published: July 2002

An interactive computer system operational on a graphical computer terminal is described. This system was designed to demonstrate a method of programming by computer interpretation of a flowchart. The user draws a description of a sampled-data system and specifies an original input signal on a display oscilloscope. This graphical description is transmitted to a large scale computer. The design is simulated, and a graphic representation of the processed signal is returned to the scope. A successful design may require numerous modifications of the original design. A graphical interactive system provides an environment to perform this iterative process efficiently and effectively.
A programming system for the on-line analysis of biomedical images
Authors: Hodes Louis
Published: July 2002

A preliminary description of the software for a computer-display system is given with special emphasis on the man-machine interaction. This system is intended for a wide variety of biomedical applications. As an example, the methods are applied to the karyotyping of chromosomes. The system is separated into four programming tasks: picture transformations, file maintenance, picture structuring, and display management. Picture structuring is considered as the vehicle for man-machine communication. A prototype data format for pictures, called a picture-form, is developed. Structure operators are defined which manipulate picture-forms to produce new picture-forms. Many of the ideas are taken from the symbolic mathematical laboratory at MIT conceived by Marvin Minsky.
Operations on generalized arrays with the genie compiler
Authors: Sitton G. A.
Published: July 2002

Operations on vectors, matrices, and higher dimensional storage arrays are standard features of most compilers today. The elements of such structures are usually restricted to be scalars. For many sophisticated applications this restriction can impose cumbersome data representations. An efficient system has been devised and implemented which allows the elements of multi-dimensional arrays to themselves be multidimensional arrays. This system was developed from a storage structure in which the location, length, and content of each array is described by a codeword which can be interpreted by the system. Codewords may describe arrays containing more codewords, thus providing all needed descriptive information for hyperstructures of any form.
Conversion of limited-entry decision tables to computer programs—a proposed modification to Pollack's algorithm
Authors: Shwayder Keith
Published: July 2002

Pollack has proposed an algorithm for converting decision tables into flowcharts which minimize subsequent execution time when compiled into a computer program. Two modifications
o
this algorithm are proposed. The first relies on Shannon's noiseless coding theorem and the communications concept of entropy but does not completely test the ELSE Rule. The second modification completely tests the ELSE Rule but results in more executions than the first modification. Both modifications result in lower execution time than Pollack's algorithm. However, neither modification guarantees a globally optimal solution.
A note on compiling fixed point binary multiplications
Authors: Gladwin H. Tim
Published: July 2002

An algorithm is developed for compiling, as a sequence of shifts, additions, and subtractions, many fixed point binary multiplications involving a constant. The most significant characteristics of the algorithm are the simplicity of the test which determines if the algorithm should be applied and the degree to which it “suggests” efficient object code.
A code for non-numeric information processing applications in online systems
Authors: Morenoff Edward , McLean John B.
Published: July 2002

A code has been specifically designed to simplify the internal information processing operations within an online computer system with respect to non-numeric applications, and to maximize the transfer rate of the information channel linking the system and the system user. The code has direct application to problems in areas such as information retrieval, document classification, computer-aided teaching and text editing.

This code, called IPC (Information Processing Code), is an 8-bit code set constructed so that 7, 6, 5 and 4-bit subsets can be easily derived from the basic set. The code set is organized so that simple binary operations can distinguish between the numeric alphabetic, special symbol and control character codes. The number of useable characters within the basic set size may be expanded either by use of escape codes included in the set, or by suitable interpretation of otherwise unassigned codes on the basis of the requirements of local environments.
A unifying computational method for the analysis of complete factorial experiments
Authors: Cooper B. E.
Published: July 2002

A computational method which may be used for the calculation of sums of squares in the analysis of variance of complete factorial experiments and in the computation of main effect or interaction means is described. The method is elucidated as unifying since one method can be used for a variety of purposes each previously requiring different methods. The programming advantages of such a method are obvious. The following variants are discussed: (1) the standard analysis of variance; (2) analyses omitting certain levels of one or more factors; (3) separate analyses for some levels of a factor or for combinations of levels of more than one factor. These are performed simultaneously; (4) the calculation of main effect or interaction means.

The method expects the data in standard order and it leaves the data in that order so that many analyses of the same data can be performed without rearrangement. The total sum of squares, excluding a replication sum of squares, is partitioned into all polynomial partitions and their interactions each with one degree of freedom. This is so even if factors have unequally spaced factor levels.
On the computation of least squares polynomials
Authors: Goldberg Morton
Published: July 2002

Rounding error accumulated during digital computation of a least squares polynomial makes the computed polynomial only an approximation to the true least squares polynomial. A simple method for adjusting the constant term of the computed polynomial to get a better approximation to the true least squares polynomial is described.
Writing an online debugging program for the experienced user
Authors: Brady Paul T.
Published: July 2002

Presently available online debugging routines are often unsatisfactory for the experienced user because they require unnecessarily rigid and complicated typing formats, make it difficult for the user to correct typing errors, and consume excessive memory with intricate features. In a debugging program it is of prime importance that the program be simple, flexible, and highly efficient to use. Communication between the user and the debugging program can be improved by using certain techniques applicable to most online debugging programs.

These techniques are presented and are illustrated by their use in OPAK (octal package), a debugging program coded for the PDP-5/8 and the SDS-930.

The compromise between economy of utility program core storage and incorporation of elegant debugging features is discussed.
A user-oriented time-shared online system
Authors: Betyar Laszlo
Published: July 2002

An existing system and planned additions within the Data Processing Laboratory of the Brain Research Institute at UCLA is described. The system represents an attempt to provide research workers of the Institute with the ability to interact directly with a highly sophisticated digital computing complex in the most direct and simple fashion possible. It is anticipated that, with the accumulation of experience using the present system, significant advances will be possible in the system design through determination of interface parameters between the biological scientist and the digital computer.
A method for finding Hamilton paths and Knight's tours
Authors: Pohl Ira
Published: July 2002

The use of Warnsdorff's rule for finding a knight's tour is generalized and applied to the problem of finding a Hamilton path in a graph. A graph-theoretic justification for the method is given.
Advanced cryptographic techniques for computer
Authors: Van Tassel Dennie
Published: July 2002

Cryptographic techniques which can be used to maintain the confidentiality of information processed by computers are dealt with. Special emphasis is paid to the unique characteristics of computer files that make many cryptographic methods of little use. Relative security, costs, and preferred methods are included in this paper.
PLEXUS—an on-line system for modeling neural networks
Authors: Dill J. C. , Randall D. L. , Richer I.
Published: July 2002

A description is presented of PLEXUS, a system which enables a user to construct and specify a neural network, to analyze the output data produced by the network, and to store and retrieve networks and data from a library. The system, operated entirely from a digital display unit, interacts directly with the user and permits easy and rapid transitions between the various phases of the modeling process. PLEXUS is designed to complement neurophysiological research so that the systematic development of neural models can be coordinated with experimental work.

PLEXUS networks are built up from components representing individual neurons, external stimuli, and interconnecting fibers, each component being of a relatively detailed nature. Provision is also made for the use of experimental data as input to a network. Convenient means for specification and modification of a network and extensive error-checking capabilities are provided. Data resulting from the simulation of a network may be analyzed by a variety of techniques ranging from examinations of the gross characteristics of the data to the determination of detailed statistical properties.
Storage organization in programming systems
Authors: Jodeit Jane G.
Published: July 2002

The system of program and data representation that has been in use on the Rice University computer for five years is described. Each logical entity in storage occupies a block of consecutive memory locations. Each block is labeled by a
codeword
and may contain a program, a data vector, or codewords which in turn label blocks to form arrays. This storage arrangement is discussed with its realized advantages in programming systems: simplicity of programmed addressing, flexibility of data structures, efficiency of memory utilization, variability of system composition during execution, means of linkage between programs and from programs to data, and basis for storage protection. The application of labeled blocks may be extended to areas of time-sharing and multi-media storage control. On the basis of experience at Rice, some ideas on such extensions are presented.
An automatic loader for subroutine nests
Authors: Kanner Herbert
Published: July 2002

A method for automatic loading of library subroutines, which can be adapted to operate in conjunction with any conventional two-pass assembler is described. The method is specifically designed to cope with a nested library structure.
Autosate
Authors: Gatto O. T.
Published: July 2002

An automated data system analysis technique is described. The technique is designed to alleviate some of the principal problems that beset current analysis—large data workloads, long span of time between project inception and system operational date, the lack of explicit directions for conducting data system analysis and using the results, and the lack of a technique to control data system changes throughout its lifetime. The analysis is geared to determining workload, relationships and storage characteristics of documents in the information network automatically.
A graphical service system with variable syntax
Authors: Roberts Lawrence G.
Published: July 2002

Man-machine interaction in many fields of endeavor should be greatly facilitated in the near future through the use of interactive graphical languages. To provide a variety of display scope communication procedures, a Graphic Service System which functions as a generalized graphical language translator, is being developed to aid the definition as well as the use of new graphical languages.