bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficient massively parallel simulation of dynamic channel assignment schemes for wireless cellular communications
Authors: Greenberg Albert G. , Lubachevsky Boris D. , Nicol David M. , Wright Paul E. 
Published: January 2007

Fast, efficient parallel algorithms are presented for discrete event simulations of dynamic channel assignment schemes for wireless cellular communication networks. The driving events are called arrivals and departures, in continuous time, to cells geographically distributed across the service area. A dynamic channel assignment scheme decides which call arrivals to accept, and which channels to allocate to the accepted calls, attempting to minimize call blocking while ensuring co-channel interference is tolerably low. Specifically, the scheme ensures that the same channel is used concurrently at different cells only if the pairwise distances between those cells are sufficiently large. Much of the complexity of the system comes from ensuring this separation.The network is modeled as a system of interacting continuous time automata, each corresponding to a cell. To simulate the model, we use conservative methods; i.e., methods in which no errors occur in the course of the simulation and so no rollback or relaxation is needed. Implemented on a 16K processor MasPar MP-1, an elegant and simple technique provides speedups of about 15x over an optimized serial simulation running on a high speed workstation. A drawback of this technique, typical of conservative methods, is that processor utilization is rather low. To overcome this, we developed new methods that exploitslacknessin event dependencies over short intervals of time, thereby raising the utilization to above 50% and the speedup over the optimized serial code to about 120x with respect to the workstation simulation.
URPR—An extension of URCR for software pipelining
Authors: Su B. , Ding S. , Xia J. 
Published: January 2007

The software pipeline technique is an effective approach to optimizing loops in array processor programs, but existing methods are of high complexity and the results may not be satisfactory.
This paper introduces the URPR algorithm, an extension of the microcode loop compaction algorithm URCR. Firstly, unroll the loop(the number of unrolled loop bodies relies on the inter-body data dependency); secondly, pipeline the unrolled loop bodies one by one; and finally, a new optimized loop body is obtained after rerolling. Preliminary tests indicate that URPR produces favorable results with lower complexity.
Design and realization of MLM: a multilingual machine
Authors: Franca F. M G , Vasconcelos N. Q. , Fernandes E. S T 
Published: January 2007

This paper describes the design and realization of MLM, a Multi-Lingual machine whose main goal is to provide support for teaching and research in Microprogramming and Computer Architecture. MLM is based on a standard (non-microprogrammable) minicomputer whose microarchitecture has been modified in order to satisfy the requirements of a multi-lingual environment.
The resulting machine is microprogrammable, offers facilities for interpreting different target repertoires, and has means to switch from one instruction set to another. MLM implements the concept of dynamic microprogramming, and in its current version there are two control stores defining two conventional levels at any time: the first is the conventional level fixed by the host manufacturer (in PROM); the second may be specified by the user.
In addition to the design and implementation issues, the paper also outlines the research potential of MLM and describes the current stage of the work.
Clustered time warp and logic simulation
Authors: Avril Hervé , Tropper Carl 
Published: January 2007

We present, in this paper, a hybrid algorithm which makes use of Time Warp between clusters of LPs and a sequential algorithm within the cluster. Time Warp is, of course, traditionally implemented between individual LPs. The algorithm was implemented in a digital logic simulator, and its performance compared to that of Time Warp.
Resting upon this platform we develop a family of three checkpointing algorithms, each of which occupies a different point in the spectrum of possible trade-offs between memory usage and execution time. The algorithms were implemented on several digital logic circuits and their speed, number of states saved and maximal memory consumption were compared to those of Time Warp. One of the algorithms saved between 35 and 50% of the maximal memory consumed by Time Warp (depending upon the number of processors used), while the other two decreased the maximal usage up to 30%. The latter two algorithms exhibited a speed comparable to Time Warp, while the first algorithm was 30-60% slower.
These algorithms are also simpler to implement than optimal checkpointing algorithms.
A fast asynchronous GVT algorithm for shared memory multiprocessor architectures
Authors: Gomes Z. Xiao F. , Unger B. , Cleary J. 
Published: January 2007

The computation of Global Virtual Time is of fundamental importance in Time Warp based Parallel Discrete Event Simulation Systems. Shared memory multiprocessor architectures can support interprocess communication with much smaller overheads than distributed memory systems. This paper presents a new, completely asynchronous, Gvt algorithm which provides very fast and accurate Gvt estimation with significantly lower overhead than previous approaches. The algorithm presented is able to support more efficient memory management, termination, and other global control mechanisms.
The Gvt algorithm described enables any Time Warp entity to compute Gvt at any time without slowing down other entities, in particular, those executing on the critical path. Experimental results are presented for a shared memory Time Warp system that employs a two tiered distributed memory management scheme.
The proof of the correctness and the accuracy of the algorithm are also presented. Finally, some suggestions on possible further optimization of the implementation are given.
Control of structure and evaluation
Authors: Benkard J. Philip 
Published: January 2007

Scalar conformance controls the structure phase of expression evaluation. Program control of this phase is achieved through insertion and deletion of scalar levels of structure. The basic functions to do this are ENCLOSE and DISCLOSE with axis. Their application in some common cases is made easier with proposed extensions to BRACKET INDEX and INTERVAL. This approach provides the function of a RANK operator with greater flexibility while keeping data structure information with the data.
A number of simple expression transformations have proved useful experimentally. Two operators are defined which in their several invocations provide full and partial currying and commutation of left and right arguments; composition, power, and dual of functions; composition, conversion between dyadic and monadic function syntax.
The variations in the definitions of partitions have led to suggestions that more than one primitive operation may be needed. Extensions to EACH and ENCLOSE are proposed which provide a wide range of function while satisfying numerous identities. Since these two operations are each used in APL2 to create a level of structure, the extensions are appropriate.
On the parameters of human visual performance: an investigation of the benefits of antialiasing
Authors: Booth Kellogg S. , Bryden M. Philip , Cowan Wiliam B. , Morgan Michael F. , Plante Brian L. 
Published: January 2007

A two-part experiment was conducted to investigate the effects of aliasing artifacts and screen resolution on a simple visual recognition task. The results indicate that in many cases far less realism may be necessary in synthetic computer-generated imagery than is often assumed in the literature. The first part of the experiment comprised a subjective rating of image quality, the second part measured task effectiveness of image quality. In the second part subjects were asked to discriminate between images of two types of objects built from cubes, similar to objects used in experiments involving mental rotation.At higher resolutions the elimination of aliasing artifacts did not significantly improve subjects' performance. At intermediate and low resolutions, comparable to what might be used for iconic menus, the reduction in aliasing artifacts resulted in improved performance. The subjective ratings indicate that for both high and low resolution the elimination of aliasing artifacts does not improve “quality,” whereas images rendered at intermediate resolutions are significantly degraded by aliasing artifacts to the extent that antialiasing improves the subjective rating.An interpretation of these results is given in the context of an ongoing research program aimed at identifying the parameters of real-time human performance for graphics workstations.
The analysis and performance of batching arbiters
Authors: Kleeman Lindsay , Cantoni Antonio 
Published: January 2007

A class of arbiters, known as batching arbiters, is introduced and defined. A particularly simple decentralised example of a batching arbiter is described, with motivation given for the batching arbiter model adopted. It is shown that under reasonable assumptions, batching arbiters can be described by a finite state Markov chain. The key steps in the analysis of the arbiter performance are the method of assigning states, evaluation of state transition probabilities and showing that the Markov chain is irreducible. Arbiter performance parameters are defined, such as proportion of time allocated to each requester and mean waiting time for each requester. Apart from results describing the steady state behavior of the arbiter for general system parameters, a number of limiting results are also obtained corresponding to light and heavy request loading.
Finally, numerical results of practical interest are presented, showing the performance parameters of the arbiter versus request rates for various configurations.
An axiomatization of low-level parallelism in microarchitectures
Authors: Damm Werner 
Published: January 2007

This paper presents the heart of a universal syntax-directed proof system for the verification of horizontal computer architectures.
The system is based on the axiomatic architecture description language AADL, which incorporates a comcise model of clocked microarchitectures. For a given description A of a host architecture, we show how to axiomatize A's microoperations and present powerful proof-rules dealing with the inherent low-level parallelism of horizontal architectures. They allow for a complete axiomatic treatment of the timing behaviour and dynamic conflicts of microprograms written in an A-dependent high-level microprogramming language based on S*.
System development methodology using LOGOS
Authors: Allen David B. , Dempsey Mark R. , Goldsmith Leslie H. 
Published: January 2007

The development of applications written in APL has traditionally both benefited by and suffered from the freedom offered by the environment. A consequence of this freedom is that few applications are designed from the perspectives of consistency, modularity, and structure. This paper describes how LOGOS, a programming environment for APL, helps improve the development and maintenance of APL applications. Through the use of basic support facilities and integrated tools, LOGOS encourages a modular design within applications and a greater consistency among them. The support facilities provide such functionality as the paging of large applications, or the parallel testing of multiple versions of software, with minimal effort.
Specific examples of system design and development are given in the paper. Programming methodologies in widespread practice are examined, and their application to APL with LOGOS is described. The use of LOGOS in top-down design and in application prototyping is also discussed.
A second generation DOMINO for statisticians
Authors: Sykes Alan 
Published: January 2007

The use of 'domino' (⊞) is one of the many attractive features of APL. To a statistician, it is particularly useful in its dyadic form, returning least-squares estimates Y⊞D necessary to predict data in the 'Y' vector using as prediction variables, the columns of the “design matrix” D.
Second generation APL interpreters supporting nested array structures present a unique opportunity to make such dyadic uses of domino even more attractive. The householder algorithm employed by domino provides much information that is lost to the user. This paper discusses how this information can be captured by Y⊞D returning a nested array. The essential ideas are presented using APL functions. An auxiliary processor written in C for the Dyalog interpreter demonstrates an implementation of these ideas.
APL thinking: examples
Authors: Eisenberg Murray , Peelle Howard A. 
Published: January 2007

In an effort to understand “APL thinking”, we examine a few selected examples of using APL to solve specific problems, namely: compute the median of a numerical vector; simulate the Replicate function; string search; carry forward work-to-be-done in excess of capacity; rotate concentric rectangular rings in a matrix; find column indices of pivots in an echelon matrix.
These examples are drawn from our teaching experience as well as from APL literature. We are particularly interested in studying thinking processes underlying alternative solutions to such problems — i.e., our goal is to “get inside the head” of the APL programmer. Analyses include reconstructing thoughts, comparing alternative approaches, and, in general, scrutinizing supposed characteristics of APL thinking.
Teaching social studies concepts using concrete models expressed in APL
Authors: Traberman Tama 
Published: January 2007

Concepts routinely used in middle and secondary social studies classes are often too abstract for students to comprehend. To fully understand the concept of nation, for example, students must first visualize and comprehend the notions of territory, boundaries, governments, cultures, history and shared goals and dreams for the future as well as other abstractions that may be subsumed in the word.
The problem becomes more complex when the teacher works with social studies concepts that are expressed numerically. When students work with familiar numbers in the tens and hundreds, they often have difficulty conceptualizing such ideas as population density and per capita income, which are expressed in terms or a single unit. When the numbers are in the billions or trillions, they are difficult to visualize and to comprehend. When the large numbers are used in social studies concepts such as gross national product, the problem compounds. Students may also lack skill in using mathematical functions involving these large numbers.
Teachers want students to understand rich and powerful ideas and they search for classroom activities to enhance student learning. Instructional techniques which provide students with concrete experiences and which allow for manipulation of the environment help students master such concepts. These strategies help students develop the ability to do abstract and formal thinking.

This paper focuses on concepts in global studies and presents some techniques for teaching these abstract ideas using computer models expressed in
APL.
Students manipulate these models in a variety of ways in class. Students learn to do research, store information and access and use data to comprehend their world more fully.
The engineering computer library (ENGLIB) an APL system for increased engineering productivity
Authors: Ward Harold R. 
Published: January 2007

Choosing APL as the primary environment for engineering computer usage requires careful consideration of the extremes of computer usage sophistication, amounts of computation and storage, and types of computer programs. A system of APL workspaces is described which enables a small group of engineering technicians to provide appropriate computing support to a large group of users in and outside the Engineering Department.
ENGLIB is developed as a working model for a practical, conceptually simple environment for engineering data processing with facilities for handling and expediting all phases of engineering computer usage. Computer support ranging from routine job production to highly technical engineering programming to computer education is accomplished using APL as the background for man-machine synergy and interpersonal communication. Featured are interfaces to non-APL software and data storage/retrieval systems and a general description of the major sub-systems and key peripheral functions which enable ENGLIB to fit and increase engineering productivity.
Extending APL
Authors: Bozinovic Dragan 
Published: January 2007

This paper explores certain underdeveloped parts of APL which ought to grow if APL is to qualify as implementation language for large and maintainable software systems. Following specific problems are discussed:
* Integrating APL with other parts of information processing environment.
• Operating systems.
• Programs written in other languages.
• Data bases.
* Using independently developed functions and subsystems.
• Problems with names.
• Problems with space.
* Execution control of object attributes.
* Communications among functions.
• Passing parameters.
• Returning values.
• Transferring control.
* Information hiding modules.
• Packaging related functions.
• Packaging data with functions.
• Local functions.
Experimental mathematics using APL and graphics
Authors: Haspel Charles , Vasquez Alphonse 
Published: January 2007

Mathematics is ordinarily done by examining computations to extract likely conjectures. Only later are the conjectures proved, and, in traditional practice, the computations and motivations suppressed. We describe a computational investigation of the geometry of fundamental domains and units in totally real algebraic number fields. Our approach requires the finding of convex hulls in three dimensional space and their display and manipulation. APL and graphics are used for this purpose and appear to be essential for any practical pursuit of this approach.
This paper presents a definition of the problem, an example solution including drawings and portions of the APL code, and a sample of the results so far obtained. In addition, lessons learned from our own mistakes and fumblings are drawn to help and encourage other experimental mathematics explorations.
AP19 - a shared variable terminal I/O interface for APL systems
Authors: Hartigan Bruce J. 
Published: January 2007

AP19 is an auxiliary processor which provides access, through the medium of shared variables, to the terminal input/output processor of an APL system. It allows the user to bring the power of APL to bear upon the management of subordinate and deferred sessions. This paper presents an overview of the design and development of AP19, describes its characteristics from a user's point of view, and gives some examples of how it has been used.
Insofar as AP19 is a component of an IBM internal version of APLSV, it is not available to customers. This paper does not constitute a commitment by IBM to provide such a facility, nor is it to be construed as an indication of future product direction.
Expert systems—a technology for intelligent assistance
Authors: Reinstein Harry C. 
Published: January 2007

Researchers in artificial intelligence have developed several systems capable of providing an expert level of assistance in solving complex problems. Areas addressed have included medical diagnosis and therapy, determination of molecular structure, design of experiments in molecular genetics, and application definition. These systems are generating interest in both the industrial and academic communities, and widespread development is beginning to emerge.
Expert systems share a common architecture and this presentation will describe this architecture and contrast it with classical problem solving techniques. Several examples of these systems will be discussed, including a new expert system developed at the IBM Scientific Center in Palo Alto. While most expert systems have been programmed in LISP, this one was built using APL, and the experience has illuminated both strengths and weaknesses of APL as a language for this area of artificial intelligence.
Nested arrays as an extension for APL
Authors: Jenkins Michael A. 
Published: January 2007

This workshop will be held to inform interested members of the APL community about current research on adding nested arrays to APL.
The Chairman will present a brief summary of current research in the area, indicating the issues that are yet unresolved, and presenting a set of criteria for deciding them. Each panel member will speak briefly to the issues and then an open discussion will follow.
APL and LISP—should they be combined, and if so how?
Authors: Burge William H. , Moses Joel , Pratt Vaughan R. , Perlis Alan J. 
Published: January 2007

APL and LISP are very similar languages—both manipulate a complex data structure and the functional structure of the languages has been ideally chosen for convenient manipulation of these structures. Proposals have been made to combine them by embedding one within the other. Another approach is generalization of each into a common superior. This paper will argue that a superior language probably won't work and will then treat the issues by which the proper embedding choice should be made.
The talk will be followed by a panel discussion about the relationship between APL and LISP.
Smalltalk and generic concepts in programming languages
Authors: Kay Alan C. 
Published: January 2007

Early generic concepts in programming languages were mixed-type arithmetic (e.g., “+” used with any combination of fixed-and floating-point numbers) and “print” functions which could be applied to any of a language's objects. Generic concepts reduce the number of terms which must be remembered and permit considerable condensation of language design. Three different paths in the development of generic-concept languages have been followed by APL, Algol 68, and object-oriented languages such as SIMULA 67 and Smalltalk. APL was the earliest and one of the most interesting applications of generic-concept methods, but now makes the weakest use of these ideas.
My talk will use slides and movies to show how the message-object programming system Smalltalk makes use of generic concepts embedded in class descriptions to give rise to a wide variety of simply programmed dynamic simulations including graphic animation, music synthesis, document layout and retrieval, and APL-like calculation features. Many of these systems have been brought to life by child and adult novice programmers.
A short list of references is given for those wishing more introductory information about Smalltalk.
User-interface design for a clinical neurophysiological intensive monitoring system
Authors: Collura T. F. , Jacobs E. C. , Burgess R. C. , Klem G. H. 
Published: January 2007

We describe the functional requirements and design reasoning leading to a user-interface for an automated clinical neurophysiological monitoring system. The design provides a versatile, high-performance system in which computer-naive users have access to functions typically requiring dedicated training.
The system provides real-time data acquisition, signal processing, and graphical output, specifically tailored for the diagnosis and characterization of cases of epilepsy. The development of a user-interface was based on a collaborative effort, in which designers and users worked with a common functional model, and developed working metaphors for system operations. In addition, an interactive screen was designed to facilitate the management of multiple concurrent operations in an intuitive and easy to learn fashion.