2816368
Mobile, dexterous, social robots for mobile manipulation and human-robot interaction
A tractor 10 is disclosed for engaging and advancing a web of paper 20 by engaging a series of holes 21 along an edge of the paper 20. The tractor 10 includes a pair of parallel side plates 12, 14 and an elongated guide member 32 defining a continuous guide track 34. The guide member 32 is positioned between the side plates 12, 14 so as to define a continuous guide channel 36 in cooperation with the guide plates 12, 14. The tractor 10 also includes a drive belt assembly 22 comprising a continuous belt 62 carrying a plurality of spaced drive members 38 adapted to engage the holes 21 along the edge of the paper 20. A drive sprocket 33 located at one end of the guide channel 36 engages the drive members 38. Each guide member 38 has a hemicylindrically shaped base 64 with a notch 66 therein, thereby defining two parallel edges 67 which ride along the guide track 34. Additionally, each drive member 38 includes a drive pin 80, the profile of the surface of the drive pin 80 has the shape of a segment of an involute.
2677077
Context interchange: new features and formalisms for the intelligent integration of information
The Context Interchange strategy presents a novel perspective for mediated data access in which semantic conflicts among heterogeneous systems are not identified a priori, but are detected and reconciled by a context mediator through comparison of contexts axioms corresponding to the systems engaged in data exchange. In this article, we show that queries formulated on shared views, export schema, and shared “ontologies” can be mediated in the same way using the Context Interchange framework. The proposed framework provides a logic-based object-oriented formalsim for representing and reasoning about data semantics in disparate systems, and has been validated in a prototype implementation providing mediated data access to both traditional and web-based information sources.
5563723
Data Integration Using Web Services
In this paper we examine the opportunities for data integration in the context of the emerging Web Services systems development paradigm. The paper introduces the programming standards associated with Web Services and provides an example of how Web Services can be used to unlock heterogeneous business systems to extract and integrate business data. We provide an introduction to the problems and research issues encountered when applying Web Services to data integration. We provide a formal definition of aggregation (as a type of data integration) and discuss the impact of Web Services on aggregation. We show that Web Services will make the development of systems for aggregation both faster and less expensive to develop. A system architecture for Web Services based aggregation is presented that is representative of products available from software vendors today. Finally, we highlight some of the challenges facing Web Services that are not currently being addressed by standards bodies or software vendors. These include context mediation, trusted intermediaries, quality and source selection, licensing and payment mechanisms, and systems development tools. We suggest some research directions for each of these challenges.
9033123
Process Aggregation Using Web Services
This paper examines the opportunities and challenges related to data and process integration architectures in the context of Web Services. A primary goal of most enterprises in today's economic environment is to improve productivity by streamlining and aggregating business processes. This paper illustrates how integration architectures based on Web Services offer new opportunities to improve productivity that are expedient and economical. First, the paper introduces the technical standards associated with Web Services and provides business example for illustration. Abstracting from this example, we introduce a concept we call Process Aggregation that incorporates data aggregation and workflow to improve productivity. We show that Web Services will have a major impact on Process Aggregation, making it both faster and less expensive to implement. Finally, we suggest some research directions relating to the Process Aggregation challenges facing Web Services that are not currently being addressed by standards bodies or software vendors. These include context mediation, trusted intermediaries, quality and source selection, licensing and payment mechanisms, and systems development tools.
17041428
Context interchange in a client-server architecture
Abstract Many organizations today require information from diverse information systems, and government efforts are moving toward a national information infrastructure for sharing information. However, the systems used by these organizations lack the capabilities to meaningfully translate information among semantically heterogeneous environments. Because the meaning of data acquired from a source environment is usually different from that needed or expected in the receiver's environment, the effectiveness of information exchange is dependent on the system's capability for context interchange, i.e., the representation, exchange, comparison, and transformation of context knowledge. We show here a practical means for developing context interchange capabilities in a client-server architecture by use of semantic values (i.e., data and their context(as the unit of data exchange. The key components in this architecture are the context mediator server, whose job is to identify and construct the semantic values being sent, determine when the exchange is meaningful, and convert the semantic values to the form required by the client (i.e., receiver), and the data environment server, whose job is to assist in the location, access, development, and maintenance of the context knowledge for all clients and servers.
3110757
Context Knowledge Representation and Reasoning in the Context Interchange System
The Context Interchange Project presents a unique approach to the problem of semantic conflict resolution among multiple heterogeneous data sources. The system presents a semantically meaningful view of the data to the receivers (e.g. user applications) for all the available data sources. The semantic conflicts are automatically detected and reconciled by a Context Mediator using the context knowledge associated with both the data sources and the data receivers. The results are collated and presented in the receiver context. The current implementation of the system provides access to flat files, classical relational databases, on-line databases, and web services. An example application, using actual financial information sources, is described along with a detailed description of the operation of the system for an example query.
8004380
A Well-Posed Numerical Method to Track Isolated Conformal Map Singularities in Hele-Shaw Flow
We present a new numerical method for calculating an evolving 2D Hele-Shaw interface when surface tension effects are neglected. In the case where the flow is directed from the less viscous fluid into the more viscous fluid, the motion of the interface is ill-posed; small deviations in the initial condition will produce significant changes in the ensuing motion. This situation is disastrous for numerical computation, as small roundoff errors can quickly lead to large inaccuracies in the computed solution. Our method of computation is most easily formulated using a conformal map from the fluid domain into a unit disk. The method relies on analytically continuing the initial data and equations of motion into the region exterior to the disk, where the evolution problem becomes well-posed. The equations are then numerically solved in the extended domain. The presence of singularities in the conformal map outside of the disk introduces specific structures along the fluid interface. Our method can explicitly track the location of isolated pole and branch point singularities, allowing us to draw connections between the development of interfacial patterns and the motion of singularities as they approach the unit disk. In particular, we are able to relate physical features such as finger shape, side-branch formation, and competition between fingers to the nature and location of the singularities. The usefulness of this method in studying the formation of topological singularities (self intersections of the interface) is also pointed out.
1155385
Implementing statecharts in PROMELA/SPIN
We translate statecharts into PROMELA, the input language of the SPIN verification system, using extended hierarchical automata as an intermediate format. We discuss two possible frameworks for this translation, leading to either sequential or parallel code. We show that in this context the sequential code can be verified more efficiently than the parallel code. We conclude with a discussion of an application of the resulting translator to a well-known case study, which demonstrates the feasibility of linear temporal logic model checking of statecharts.
37254437
Exact Solutions for the Evolution of a Bubble in Stokes Flow: A Cauchy Transform Approach
A Cauchy transform approach to the problem of determining the free surface evolution of a single bubble in Stokes flow is developed. A number of exact solutions to a class of problems have been derived in the literature using conformal mapping theory, and these solutions are retrieved and further generalized using the new formulation. Certain quantities which are conserved by the dynamics are also identified, the existence of which had not previously been pointed out. A principal purpose of this paper is to use the new formulation to understand when it is possible to externally specify the evolution of the bubble area in such classes of exact solution. It is found to be possible only for certain types of far-field boundary conditions.
6090717
From Testing Theory to Test Driver Implementation
In this article we describe the theoretical foundations for the VVT-RT test system (Verification, Validation and Test for Reactive Real-Time Systems) which supports automated test generation, test execution and test evaluation for reactive systems. VVT-RT constructs and evaluates tests based on formal CSP specifications [6], making use of their representation as labelled transition systems generated by the CSP model checker FDR [3]. The present article provides a sound formal basis for the development and verification of high-quality test tools: Since, due to the high degree of automation offered by VVT-RT, human interaction becomes superfluous during critical phases of the test process, the trustworthiness of the test tool is an issue of great importance. The VVT-RT system will therefore be formally verified so that it can be certified for testing safety-critical systems. The present article represents the starting point of this verification suite, where the basic strategies for test generation and test evaluation used by the system are formally described and verified. VVT-RT has been designed to support automation of both untimed and real-time tests. The present article describes the underlying theory for the untimed case. Exploiting these results, the concepts and high-level algorithms used for the automation of real-time tests are described in a second report which is currently prepared [14]. At present, VVT-RT is applied for hardware-in-the-loop tests of railway and tramway control computers.
30791016
Extending the Limits of Sequentially Phased Reasoning
Verification via abstraction is the topic of concluding correctness of a complicated program from correctness of an abstraction of this program. Principles for sequentially phased reasoning are examples of verification via abstraction. They use permutation equivalences to abstract concurrent programs which logically work in phases to considerably simpler variants which perform these phases sequentially. It is shown in this paper that there are classes of concurrent programs, such as self-stabilizing ones, which logically work in phases but cannot be abstracted to a sequentialized version using permutation equivalence. A new class of so-called Ω-equivalences is defined which generalizes permutation equivalence and stutter equivalence. It is proved that both equivalences are indeed special cases of Ω-equivalences. A verification strategy based on Ω-equivalences is formulated and compared with existing approaches for sequentially phased reasoning. The strategy is applied to a self-stabilizing coloring program that can neither be abstracted by permutation nor by stutter equivalences to a sequentialized version.