ppxscal/embedding_network huggingface dataset:
Flexural stress waves responses on human femoral cortical bone
Authors: Fotis G. Katsamanis, Demetrios D. Raftopoulos
Venue: Technology and Health Care (2000)

The response of human femoral cortical bone to lateral impact were investigated both analytically and experimentally. In the analytical part of this investigation the Timoshenko beam theory was used for predicting the propagation of flexural stress waves along the specimens. The final solution was given in integral form and the results were obtained with the aid of a digital computer. In the experimental part of this investigation the employed specimens were obtained by cutting a human femur shaft along its length and the specimens were machined to have a uniform rectangular cross-section. Flexural stress waves in cortical bone were generated by impacting transversely 4.8 mm diameter spherical projectiles, fired from an air gun with the appropriate velocities. Stress waves were detected at two stations (positions) on the beam specimens by means of foil strain gages. These gages were suitably connected with a digital storage oscilloscope to detect the flexural stress waves produced by the lateral impact. Force history was recorded also on a storage oscilloscope by means of a sandwiched quartz crystal arrangement, of high frequency response, placed at the impact point of the specimen. A comparison was made between the corresponding analytical results and experimental data. Significant agreement was observed between them, as shown in the figures of this article.
Organizational power and the information services department
Authors: Henry C. Lucas,  Jr.
Venue: Communications of the ACM (1984)

A theory of intraorganizational power is discussed and applied to the information services department. The results of a study of the power of five departments in 40 manufacturing plants is presented. Hypotheses about the levels of power of information processing are not supported by the findings; however, the power theory in general does receive support.The information-services department is perceived as having low levels of power and influence in the organization: Reasons for this unexpected finding are discussed. The paper suggests several explanations for the results and possible problems in the organization. Recommendations to senior management and the information-services department are offered.
Software system risk management and assurance
Authors: Sharon K. Fletcher, Roxana M. Jansma, Judy J. Lim, Ron Halbgewachs, Martin D. Murphy, Gregory D. Wyss
Venue: Proceedings of the 1995 workshop on New security paradigms (1995)

Security, assurance, and risk management in software sytems are viewed in terms of three historical generations, with significant paradigm shifts occurring in each generation. The software community is currently on the brink of the third generation, and needs advances in modeling, risk theory, tools, and assurance methods. The third generation is characterized by a broader, more integrative perspective on risk, and by modeling and measurement. This paper presents a third generation framework which demonstrates the viability of an integrative and quantitive approach.
CODAS: a data display system
Authors: R. H. Day, M. K. Mansfield, M. E. Ellis
Venue: Communications of the ACM (1969)

CODAS, a Customer Oriented Data System, is a user-oriented data retrieval and display system. The command language of the system provides the user with an easy means for specifying data retrieval and display requests. Data is displayed as tables and graphs produced in a format ready for publication. In this paper the statements of the request language and the general system design are described.
Design and implementation of the parallel multimedia file system based on message distribution
Authors: Seung-Ho Park, Si-Yong Park Gwang Moon Kim, Ki Dong Chung
Venue: Proceedings of the eighth ACM international conference on Multimedia (2000)

The two-layered distributed clustered server architecture consisting of a control server and a group of storage servers has been widely used to support multimedia file systems. With this kind of the server architecture, it is easy to sustain disk load balancing and scalable disk bandwidth. However, it brings about the communication overhead between the control server and storage servers. Therefore, to reduce such overhead, media data should be transmitted from the storage servers to the users directly without the intervention of the control server. In addition, the file system must support the effective data placement and disk scheduling policies and should be designed to sustain portability and flexibility in any hardware or software environment to cope with rapidly developed hardware and software technologies. So, to fulfill such requirements described in the above statements, we designed and implemented a parallel file system named PMFS(Parallel Multimedia File System) and analyzed its performance by comparing it with PVFS(Parallel Virtual File System). As a result of our experimental simulation, we came to conclusion that the PMFS shows better performance than the PVFS does in real time data processing.
Parallel unsteady turbo-pump simulations for liquid rocket engines
Authors: Cetin C. Kiris, Dochan Kwak, William Chan
Venue: Proceedings of the 2000 ACM/IEEE conference on Supercomputing (CDROM) (2000)

This paper reports the progress being made towards complete turbo-pump simulation capability for liquid rocket engines. The Space Shuttle Main Engine (SSME) turbo-pump impeller is used as a test case for the performance evaluation of the MPI, hybrid MPI/Open-MP, and MLP versions of the INS3D code. Then, a computational model of a turbo-pump has been developed for the shuttle upgrade program. Relative motion of the grid system for rotor-stator interaction was obtained by employing overset grid techniques. Unsteady computations for SSME turbo-pump, which contains 101 zones with 31 million grid points, are carried on Origin 2000 systems at NASA Ames Research Center. The approach taken for these simulations, and the performance of the parallel versions of the code are presented.
Decentralized extrema-finding in circular configurations of processors
Authors: D. S. Hirschberg, J. B. Sinclair
Venue: Communications of the ACM (1980)

This note presents an efficient algorithm, requiring O(n log n) message passes, for finding the largest (or smallest) of a set of n uniquely numbered processors arranged in a circle, in which no central controller exists and the number of processors is not known a priori.
Strand spaces: proving security protocols correct
Authors: F. Javier Thayer Fábrega
Venue: Journal of Computer Security (1999)

A strand is a sequence of events; it represents either an execution by a legitimate party in a security protocol or else a sequence of actions by a penetrator. A strand space is a collection of strands, equipped with a graph structure generated by causal interaction. In this framework, protocol correctness claims may be expressed in terms of the connections between strands of different kinds. Preparing for a first example, the Needham-Schroeder-Lowe protocol, we prove a lemma that gives a bound on the abilities of the penetrator in any protocol. Our analysis of the example gives a detailed view of the conditions under which it achieves authentication and protects the secrecy of the values exchanged. We also use our proof methods to explain why the original Needham-Schroeder protocol fails. Before turning to a second example, we introduce ideals as a method to prove additional bounds on the abilities of the penetrator. We can then prove a number of correctness properties of the Otway-Rees protocol, and we clarify its limitations. We believe that our approach is distinguished from other work by the simplicity of the model, the precision of the results it produces, and the ease of developing intelligible and reliable proofs even without automated support.
An automatic continuation strategy for the solution of singularly perturbed nonlinear boundary value problems
Authors: J. R. Cash, G. Moore, R. W. Wright
Venue: ACM Transactions on Mathematical Software (TOMS) (2001)

In a recent paper, the present authors derived an automatic continuation algorithm for the solution of linear singular perturbation problems. The algorithm was incorporated into two general-purpose codes for solving boundary value problems, and it was shown to deal effectively with a large test set of linear problems. The present paper describes how the conintuation algorithm for linear problems can be extended to deal with the nonlinear case. The results of exstensive numerical testing on a set of nonlinear singular perturbation problems are given, and these clearly demonstrate the efficacy of continuation for solving such problems.
Text categorization using hybrid (mined) terms (poster session)
Authors: C. K. P. Wong, R. W. P. Luk K. F. Wong K. L. Kwok
Venue: Proceedings of the fifth international workshop on on Information retrieval with Asian languages (2000)

This paper evaluated text categorization using charactes, bigrams, words and hybrid terms. These terms were also augmented with mined terms. Classifiers using hybrid terms did not achieve better classification performance. The use of data mining techniques to add new terms to the dictionary improves the performance of character-based classifiers. Our na&iuml;ve comparison between the Pat-tree classifier and our best classifier shows that the Pat-tree classifier has the best precision (77%) and our best classifier has the best recall (72%) and the lowest storage requirement (13%).
Oracle PL/SQL best practices
Authors: Steven Feuerstein
Venue:  (2001)

Oracle PL/SQL Best Practices is a concise, easy-to-use summary of best practices in the program development process. It covers coding style, writing SQL in PL/SQL, data structures, control structures, exception handling, program and package construction, and built-in packages. Complementary code examples are available on the O'Reilly web site. Includes a pull-out quick-reference card.
Fixpoint approach to the theory of computation
Authors: Zohar Manna, Jean Vuillemin
Venue: Communications of the ACM (1972)

Following the fixpoint theory of Scott, the semantics of computer programs are defined in terms of the least fixpoints of recursive programs. This allows not only the justification of all existing verification techniques, but also their extension to the handling, in a uniform manner of various properties of computer programs, including correctness, termination, and equivalence.
Information flow inference for free
Authors: François Pottier, Sylvain Conchon
Venue: Proceedings of the fifth ACM SIGPLAN international conference on Functional programming (2000)

This paper shows how to systematically extend an arbitrary type system with dependency information, and how soundness and non-interference proofs for the new system may rely upon, rather than duplicate, the soundness proof of the original system. This allows enriching virtually any of the type systems known today with information flow analysis, while requiring only a minimal proof effort.Our approach is based on an untyped operational semantics for a labelled calculus akin to core ML. Thus, it is simple, and should be applicable to other computing paradigms, such as object or process calculi.The paper also discusses access control, and shows it may be viewed as entirely independent of information flow control. Letting the two mechanisms coexist, without interacting, yields a simple and expressive type system, which allows, in particular, "selective" declassification.
Counting large numbers of events in small registers
Authors: Robert Morris
Venue: Communications of the ACM (1978)

It is possible to use a small counter to keep approximate counts of large numbers. The resulting expected error can be rather precisely controlled. An example is given in which 8-bit counters (bytes) are used to keep track of as many as 130,000 events with a relative error which is substantially independent of the number n of events. This relative error can be expected to be 24 percent or less 95 percent of the time (i.e. &sgr; = n/8). The techniques could be used to advantage in multichannel counting hardware or software used for the monitoring of experiments or processes.
Accurate floating-point summation
Authors: Peter Linz
Venue: Communications of the ACM (1970)

This paper describes an alternate method for summing a set of floating-point numbers. Comparison of the error bound for this method with that of the standard summation method shows that it is considerably less sensitive to propagation of round-off error.
Chaotic Oscillators Derived from Sinusoidal Oscillators Based on the Current Feedback Op Amp
Authors: A. S. Elwakil, M. P. Kennedy
Venue: Analog Integrated Circuits and Signal Processing (2000)

A collection of novel chaotic oscillators displaying behavior similar to that of the chaotic Colpitts oscillator and requiring the same number and type of energy storage elements is proposed. The oscillators use as an active element the current feedback op amp (CFOA) mostly employed as a current negative impedance converter (INIC). Nonlinearity is introduced through a two-terminal voltage-controlled nonlinear device with an antisymmetric driving-point characteristic. The chaos generators are designed based on sinusoidal oscillators that have been modified for chaos in a semi-systematic manner. By using CFOAs, several attractive features are attained, in particular suitability for high frequency operation. Systems of third- and fourth-order ordinary differential equations describing the chaotic behaviors are derived. Experimental results, PSpice circuit simulations and numerical simulations of the derived mathematical models are included.
Learning and Classification of Complex Dynamics
Authors: Ben North, Andrew Blake, Michael Isard, Jens Rittscher
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2000)

Standard, exact techniques based on likelihood maximization are available for learning Auto-Regressive Process models of dynamical processes. The uncertainty of observations obtained from real sensors means that dynamics can be observed only approximately. Learning can still be achieved via ¿EM-K¿¿Expectation-Maximization (EM) based on Kalman Filtering. This cannot handle more complex dynamics, however, involving multiple classes of motion. A problem arises also in the case of dynamical processes observed visually: background clutter arising for example, in camouflage, produces non-Gaussian observation noise. Even with a single dynamical class, non-Gaussian observations put the learning problem beyond the scope of EM-K. For those cases, we show here how ¿EM-C¿¿based on the Condensation algorithm which propagates random ¿particle-sets,¿ can solve the learning problem. Here, learning in clutter is studied experimentally using visual observations of a hand moving over a desktop. The resulting learned dynamical model is shown to have considerable predictive value: When used as a prior for estimation of motion, the burden of computation in visual observation is significantly reduced. Multiclass dynamics are studied via visually observed juggling; plausible dynamical models have been found to emerge from the learning process, and accurate classification of motion has resulted. In practice, EM-C learning is computationally burdensome and the paper concludes with some discussion of computational complexity.
Creating tangible interfaces by augmenting physical objects with multimodal language
Authors: David R. McGee, Philip R. Cohen
Venue: Proceedings of the 6th international conference on Intelligent user interfaces (2001)

Rasa is a tangible augmented reality environment that digitally enhances the existing paper-based command and control capability in a military command post. By observing and understanding the users' speech, pen, and touch-based multimodal language, Rasa computationally augments the physical objects on a command post map, linking these items to digital representations of the same-for example, linking a paper map to the world and Post-itâ notes to military units. Herein, we give a thorough account of Rasa's underlying multiagent framework, and its recognition, understanding, and multimodal integration components. Moreover, we examine five properties of language-generativity, comprehensibility, compositionality, referentiality, and, at times, persistence-that render it suitable as an augmentation approach, contrasting these properties to those of other augmentation methods. It is these properties of language that allow users of Rasa to augment physical objects, transforming them into tangible interfaces.
A Differentiation Index for Partial Differential-Algebraic Equations
Authors: Wade S. Martinson, Paul I. Barton
Venue: SIAM Journal on Scientific Computing (1999)

A differentiation index for nonlinear partial differential-algebraic equations is presented. Determination of the differentiation index with respect to a direction in the space of independent variables uncovers all equations that must be satisfied by Cauchy data on the hyperplane orthogonal to that direction. This index is thus a generalization of the differentiation index of differential-algebraic equations. The motivation for this work is consistent initialization of partial differential-algebraic systems. The analysis is demonstrated through several examples, including some taken from fluid dynamics and chemical engineering.
Dynamic computation migration in DSM systems
Authors: Wilson C. Hsieh, M. Frans Kaashoek, William E. Weihl
Venue: Proceedings of the 1996 ACM/IEEE conference on Supercomputing (CDROM) (1996)

We describe dynamic computation migration, the runtime choice between computation and data migration. Dynamic computation migration is useful for concurrent data structures with unpredictable read/write patterns. We implemented it in MCRL, a multithreaded DSM system that runs on the MIT Alewife machine and Thinking Machines' CM-5. We evaluate two dynamic migration heuristics relative to data migration. On a concurrent, distributed B-tree with 50% lookups and 50% inserts, the STATIC heuristic improves performance by about 17%, on both Alewife and the CM-5. The REPEAT heuristic generally performs better than the STATIC heuristic. On Alewife, with 80% lookups and 20% inserts, the REPEAT heuristic improves performance by 23%; on the CM-5, it improves performance by 46%. Our results apply to concurrent, dynamic data structures whose access patterns are only known at runtime. For regularly accessed data structures, static methods will always be applicable, but we expect future applications to be more dynamic.
Randomized Initialization Protocols for Ad Hoc Networks
Authors: Koji Nakano, Stephan Olariu
Venue: IEEE Transactions on Parallel and Distributed Systems (2000)

Ad hoc networks are self-organizing entities that are deployed on demand in support of various events including collaborative computing, multimedia classroom, disaster-relief, search-and-rescue, interactive mission planning, and law enforcement operations. One of the fundamental tasks that have to be addressed when setting up an ad hoc network (AHN, for short) is initialization. This involves assigning each of the $n$ stations in the AHN a distinct ID number (e.g., a local IP address) in the range from $1$ to $n$. Our main contribution is to propose efficient randomized initialization protocols for AHNs. We begin by showing that if the number $n$ of stations is known beforehand, an $n$-station, single-channel AHN can be initialized with probability exceeding $1-{1\over n}$, in $en + O( \sqrt {n \log n})$ time slots, regardless of whether the AHN has collision detection capability. We then go on to show that even if $n$ is not known in advance, an $n$-station, single-channel AHN with collision detection can be initialized with probability exceeding $1-{1\over n}$, in ${\frac{10n}{3}} + O(\sqrt { n \ln n})$ time slots. Using this protocol as a stepping stone, we then present an initialization protocol for the $n$-station, $k$-channel AHN with collision detection that terminates with probability exceeding $1-{1\over n}$, in ${\frac{10n}{3k}} + O \left( \sqrt { {\frac{n \ln n}{k}}}\right )$ time slots. Finally, we look at the case where the collision detection capability is not present. Our first result in this direction is to show that the task of electing a leader in an $n$-station, single-channel AHN can be completed with probability exceeding $1-{1\over n}$, in fewer than $11.37(\log n)^2 + 2.39 \log n$ time slots. This leader election protocol allows us to design an initialization protocol for the $n$-station, single-channel AHN with no collision detection that terminates with probability exceeding $1-{1\over n}$, in fewer than $5.67n + O(\sqrt {n \ln n})$ time slots, even if $n$ is not known beforehand. We then discuss an initialization protocol for the $n$-station, $k$-channel AHN with no collision detection that terminates with probability exceeding $1-{1\over n}$, in fewer than $5.67{\frac{n}{k}} + O \left (\sqrt {\frac{n \ln n}{k}} \right )$ time slots, whenever $k \leq {\frac{n}{(\log n)^3}}$.
How to vectorize the algebraic multilevel iteration
Authors: Lutz Grosz
Venue: ACM Transactions on Mathematical Software (TOMS) (2000)

We consider the algebraic multilevel iteration (AMLI) for the solution of systems of linear equations as they arise form a finite-difference discretization on a rectangular grid. Key operation is the matrix-vector product, which can efficiently be executed on vector and parallel-vector computer architectures if the nonzero entries of the matrix are concentrated in a few diagonals. In order to maintain this structure for all matrices on all levels coarsening in alternating directions is used. In some cases it is necessary to introduce additional dummy grid hyperplanes. The data movements in the restriction and prolongation are crucial, as they produce massive memory conflicts on vector architectures. By using a simple performance model the best of the possible vectorization strategies is automatically selected at runtime. Examples show that on a Fujitsu VPP300 the presented implementation of AMLI reaches about 85% of the useful performance, and scalability with respect to computing time can be achieved.
Editorial: on the ACM publications
Authors: C. C. Gotlieb
Venue: Communications of the ACM (1969)

It is proper that a professional organization periodically review its publication policy to ensure that it is fully meeting its responsibilities to its members To this purpose the President of ACM has asked the Editorial Board to formulate a five-year policy for recommendation to the Council and an ad hoc commitee of the Editorial Board is examining the question. Professor Gotlieb, through his distinguished editorial service over the past years as Editor-as-Chief of the Journal and also of Communications, has helped shape the development of ACM publications, and we are pleased to present his views in this invited editorial &mdash;M. Stuart Lynn, Editor-in-Chief
Evolution of the meta-assembly program
Authors: David E. Ferguson
Venue: Communications of the ACM (1966)

A generalized assembler called a &ldquo;meta-assembler&rdquo; is described. The meta-assembler is defined and factors which contributed to its evolution are presented. How a meta-assembler is made to function as an assembly program is described. Finally, the implication of meta-assemblers on compiler design is discussed.
Algorithms for detailed placement of standard cells
Authors: J. Vygen
Venue: Proceedings of the conference on Design, automation and test in Europe (1998)

The state-of-the-art methods for the placement of large-scale standard cell designs work in a top-down fashion. After some iterations, where more and more detailed placement information is obtained, a final procedure for finding a legal placement is needed. This paper presents a new method for this final task, based on efficient algorithms from combinatorial optimization.