Operating systems maintain and manipulate objects that represent resources such as processes, files and I/O devices. In an operating system distributed across multiple nodes, management of object state and object refe...
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Operating systems maintain and manipulate objects that represent resources such as processes, files and I/O devices. In an operating system distributed across multiple nodes, management of object state and object references is a critical factor affecting the system's architecture, performance and complexity. this paper discusses object state management and caching in AD 2, a distributed, single-system-image UNIX operating system that runs on multicomputers and clusters. AD 2 maintains the coherency of distributed objects via token abstraction; support for tokens is implemented by the Token Module, a generic state-management facility that enables AD 2 services to efficiently control access to object state that is distributed across multiple nodes. the paper details the Token Module's architecture and functionality, including the features supporting scalability, piggybacking of tokens to avoid messages, and flexibility with respect to maintaining cache coherency and resolving conflicting accesses. Also described is how AD 2 services use tokens and the associated Token Module features to implement distributed access to UNIX files, mounted file systems and shared open file structures.
the evaluation of distance learning models has become commonplace in many academic institutions. Two models tend to dominate current offerings-An expensive audio/video real time interaction place dependent model and a...
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We present a new cooperative transaction model. the model has been developed using a data-driven approach, where we have not considered constraints specific to one application class, but only data-specific constraints...
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We present a new cooperative transaction model. the model has been developed using a data-driven approach, where we have not considered constraints specific to one application class, but only data-specific constraints. this approach is more general than the application-driven approach adopted in other cooperative transaction models. the notion of a set of complementary objects is intrinsic here. Two objects belong to a set of complementary objects if they are connected by dependency relations, directly or transitively. A set of users, represented by cooperative transactions within a cooperative unit, shares the consistency preservation of a set of complementary objects (global consistency). Responsibilities are separated: the set of complementary objects is divided into disjointed subsets, each being manipulated by at most one user. Global consistency is achieved by selective cooperation between users in order to take into account the dependency relations between the respective objects that they manipulate. the model enforces two grades of selective cooperation. In weak cooperation, a user makes his final effects visible to another (one-way cooperation). In strong cooperation users make their intermediate effects symmetrically visible (two-way cooperation). Global consistency is ensured when there are concurrent transactions external to the cooperative unit, and in case of failure.
the evaluation of distance learning models has become commonplace in many academic institutions. Two models tend to dominate current offerings-an expensive audio/video real time interaction place dependent model and a...
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the evaluation of distance learning models has become commonplace in many academic institutions. Two models tend to dominate current offerings-an expensive audio/video real time interaction place dependent model and an inexpensive Internet based delayed interaction place independent model. By combining the most favorable elements of these models with technology prevalent in the MOO/MUD culture, a new MDU model was developed and field tested. this was a text based inexpensive distance learning model that offered real time interaction and place independent accessibility. the key element of this MDU or virtual learning environment (VLE) model was Diversity University-an experimental object oriented virtual reality college that enables same time different place text based interaction over the Internet. During the spring 1995 semester, it served as a platform for conducting an entire information systems (IS) seminar style graduate capping course field study. A comparative analysis was done between the VLE course and the PLE (physical learning environment) courses. the replicatable strategy and results of this successful field study are presented. It was found that the MDU model developed was able to satisfactorily replicate the real learning environment for the chosen course. Further it did so conveniently, inexpensively and without compromising the target course learning objectives. A summary of findings and recommendations is presented.
this paper describes an intelligent robotics simulation system. It acts either as an interactive robot modeling and simulation tool, or as an execution environment for robotics task plans generated by higher-level pla...
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this paper describes an intelligent robotics simulation system. It acts either as an interactive robot modeling and simulation tool, or as an execution environment for robotics task plans generated by higher-level planners. It provides features for modeling of manipulators, environment configuration, manipulator control and status reporting. It also provides an interactive simulation environment where every command entered by the user is immediately executed and the results are displayed on a graphics screen. through this interactive environment, users can change the simulation scenario and operate the robot manipulator models in the system.
the authors apply fuzzy reasoning to the placement of sea-of-gate arrays. Fuzzy logic is used to optimize a process of decision making in physical design. Multiple objectives such as utilization of area, routability, ...
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the authors apply fuzzy reasoning to the placement of sea-of-gate arrays. Fuzzy logic is used to optimize a process of decision making in physical design. Multiple objectives such as utilization of area, routability, and timing were considered simultaneously and balanced by fuzzy logic algorithms. the experiments demonstrated that solutions obtained by fuzzy logic were of much better quality than those achieved by standard techniques.< >
Synthesis of systems containing application-specific as well as reprogrammable components, such as off-the-shelf microprocessors, provides a promising approach to realization of complex systems using a minimal amount ...
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ISBN:
(纸本)0818628227
Synthesis of systems containing application-specific as well as reprogrammable components, such as off-the-shelf microprocessors, provides a promising approach to realization of complex systems using a minimal amount of application-specific hardware while still meeting the required performance constraints. We describe an approach to synthesis of such hardware-software systems starting from a behavioral description as input. the input system model is partitioned into hardware and software components based on imposed performance constraints. Synchronization between various elements of a mixed system design is one of the key issues that any synthesis system must address. In this paper, we consider software and interface synchronization schemes that facilitate communication between system components. We present tools to perform synthesis and simulation of a system description into hardware and software components. In particular, we describe a program, Poseidon, that performs concurrent event-driven simulation of multiple functional modules implemented either as a program or as behavioral or structural hardware models. Input to Poseidon consists of description of interacting functional models withtheir respective clock cycle times and the interface synchronization scheme chosen by the partitioner. the resulting software component is assumed to be implemented for the DLX machine, a load/store microprocessor. we present simulation examples and design of a graphics controller demonstrate the feasibility of mixed system synthesis.
Stochastic robustness is a simple technique used to estimate the stability and performance robustness of linear, time-invariant systems. the use of high-speed graphics workstations and control system design software i...
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Stochastic robustness is a simple technique used to estimate the stability and performance robustness of linear, time-invariant systems. the use of high-speed graphics workstations and control system design software in stochastic robustness analysis is discussed and demonstrated. It is shown that stochastic robustness makes good use of modern computational and graphic tools, and it is easily implemented using commercial control system design and analysis software.
作者:
Heyer, B.A.Walther, M.K.Abex Corp
Foundry Research & Development Mahwah NJ USA Abex Corp Foundry Research & Development Mahwah NJ USA
A computer simulation of the solidification process is described. the derivation of the mathematical model and the method of computation is described. Examples of simple shapes are used to explain the simulation and t...
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A computer simulation of the solidification process is described. the derivation of the mathematical model and the method of computation is described. Examples of simple shapes are used to explain the simulation and to establish the value of the full colour visual display used in the analysis of the model. Several practical examples of axisymmetrical two-dimensional and three-dimensional models are given. these are based on actual analyses of castings done at the request of foundry engineers in the authors' company.
thIS conferenceproceedings CONTAINS 142 PAPERS ORGANIZED AS FOLLOWS: COMMUNICATION MANAGEMENT, EDUCATION AND RESEARCH,graphics, WRITING AND EDITING AND computer TECHNOLOGY APPLICATION TECHNICAL COMMUNICATION, INCLUDI...
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thIS conferenceproceedings CONTAINS 142 PAPERS ORGANIZED AS FOLLOWS: COMMUNICATION MANAGEMENT, EDUCATION AND RESEARCH,graphics, WRITING AND EDITING AND computer TECHNOLOGY APPLICATION TECHNICAL COMMUNICATION, INCLUDING WRITING, EDITING AND INFORMATION DOCUMENTATION, VARIOUS GRAPHIC MEthODS, ILLUSTRATION, PHOTOGRAPHY, PRINTING AND computergraphics, COLLEGE AND UNIVERSITY EDUCATIONAL PROGRAMS AND WORKSHOPS, ORGANIZATIONAL WRITING, TECHNICAL PUBLICATION, AND MANUAL PREPARATION, computer SYSTEM DOCUMENTATION, WORD AND TEXT PROCESSING,AND OthER FIELDS OF INFORMATION SCIENCE ARE PRESENTED. TECHNICAL AND PROFESSIONAL PAPERS FROM thIS conference ARE INDEXED WIththE conference CODE NO. 01398 IN thE EI ENGINEERING MEETINGS (TM) DATABASE PRODUCED BY ENGINEERING INFORMATION, INC.
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