Rangasami L. Kashyap

Information integration and synchronization in distributed sensor networks

The computational, i.e. architectural, algorithmic, and synchronization, issues related to competitive information integration in a distributed sensor network (DSN) are addressed. The proposed DSN architecture consists of a set of binary trees whose roots are fully connected. Each node of the tree has a processing element and one or more sensors associated with it. The information from each of the sensors has to be integrated in such a manner that the communication costs are low and that the real time needs are met. An information integration algorithm that has a low message cost (linear in the number of nodes of the network) and a low distributed computation cost is presented. The problems associated with synchronizing information to be integrated in the presence of imperfect clocks is considered. The fault tolerant features of the network and the integration algorithm are discussed. >

A visual query language for graphical interaction with schema-intensive databases

This paper presents a visual query language called VQL for interacting with an object-oriented schema-intensive data model. VQL allows convenient access to the various types of knowledge captured by the semantic model. It consists of a set of graphical primitives along with a combination grammar for creating graphical queries. The visual language is internally supported by a prolog-like predicate based query language. The formal grammar underlying the predicate based language is also presented. Apart from being able to create simple queries that can be specified in SQL or QBE, VQL can be used for making queries on any object-oriented data model including the generalization of the E-R model. VQL also handles complicated, indirect queries, specially those that require a reasoning system for query interpretation and response generation. Further, recursive queries on graph structures such as finding transitive closures of graphs may be easily specified. Perhaps the most powerful feature of VQL is its ability to provide high semantic expressibility (in being able to specify highly complex queries) while maintaining simplicity in the users query formulation process. VQL is embedded in an object-oriented graphical database interaction environment that supports schema creation and manipulation in addition to database querying and updation. The prototype has been implemented in Smalltalk-80 running on a Sun 3/60 workstation. All the illustrations of visual interaction presented are taken from actual interaction sessions. >

Belief combination and propagation in a lattice-structured interference network

Belief propagation and belief combination procedures based on the Dempster-Shafer belief function for inference in rule-based systems is proposed. The belief combination procedure yields results identical to those of Dempsters rule when pieces of evidence are independent. Dempsters rule is shown to be nonrobust for combining evidence with a high degree of conflict. The cause of the nonrobustness is discussed, and an alternative belief combination procedure to remedy the deficiency is proposed. Although the proposed procedure yields results that are dependent on the interpretations of the rule, it is shown to be an interpolation between total ignorance and the uncertainty associated with the rule regardless of the interpretations. When the rule interpretation yields an associative belief propagation procedure, a corresponding chaining syllogism for it can be derived. The proposed inference procedures are applied to a lattice-structured inference network. >

IDENTIFYING OVERLAPPED OBJECTS FOR VIDEO INDEXING AND MODELING IN MULTIMEDIA DATABASE SYSTEMS

The identification of the overlapped objects is a great challenge in object tracking and video data indexing. For this purpose, a backtrack-chain-updation split algorithm is proposed to assist an unsupervised video segmentation method called the simultaneous partition and class parameter estimation (SPCPE) algorithm to identify the overlapped objects in the video sequence. The backtrack-chain-updation split algorithm can identify the split segment (object) and use the information in the current frame to update the previous frames in a backtrack-chain manner. The split algorithm provides more accurate temporal and spatial information of the semantic objects so that the semantic objects can be indexed and modeled by multimedia input strings and the multimedia augmented transition network (MATN) model. The MATN model is based on the ATN model that has been used in artificial intelligence (AI) areas for natural language understanding systems, and its inputs are modeled by the multimedia input strings. In this paper, we will show that the SPCPE algorithm together with the backtrack-chain-updation split algorithm can significantly enhance the efficiency of spatio-temporal video indexing by improving the accuracy of multimedia database queries related to semantic objects.

A spatio-temporal semantic model for multimedia database systems and multimedia information systems

As more information sources become available in multimedia systems, the development of abstract semantic models for video, audio, text, and image data is becoming very important. An abstract semantic model has two requirements: it should be rich enough to provide a friendly interface of multimedia presentation synchronization schedules to the users and it should be a good programming data structure for implementation in order to control multimedia playback. An abstract semantic model based on an augmented transition network (ATN) is presented. The inputs for ATNs are modeled by multimedia input strings. Multimedia input strings provide an efficient means for iconic indexing of the temporal/spatial relations of media streams and semantic objects. An ATN and its subnetworks are used to represent the appearing sequence of media streams and semantic objects. The arc label is a substring of a multimedia input string. In this design, a presentation is driven by a multimedia input string. Each subnetwork has its own multimedia input string. Database queries relative to text, image, and video can be answered via substring matching at subnetworks. Multimedia browsing allows users the flexibility to select any part of the presentation they prefer to see. This means that the ATN and its subnetworks can be included in multimedia database systems which are controlled by a database management system (DBMS). User interactions and loops are also provided in an ATN. Therefore, ATNs provide three major capabilities: multimedia presentations, temporal/spatial multimedia database searching, and multimedia browsing.

Case-based reasoning and learning in manufacturing with the TOLTEC planner

The research presented concentrates on bringing together case-based reasoning and expert knowledge-based reasoning in a planner called TOLTEC. The experts domain-specific knowledge is modelled as dynamic memory structures and this representation is used to help the planner reason and control its planning process. TOLTEC uses a complex indexing of its cases, so as to allow incremental retrieval. The TOLTEC planner is applied to a highly constrained domain, and it is shown how the final plan is created by adding memory- and situation-selected chunks of subtask expansion to each subtask, until the problem is reduced to primitive (nonexpandable) tasks. It is also shown how the use of dynamic memory structures and dynamic, user-directed backtracking allows the planner to predict and discover failures, recover from them, and modify its knowledge according to them. Finally, it is shown how in a domain of multiple possible solutions for each goal the methodology developed allows the planner to slowly model itself to the preferences of the user. The paper also discusses some of the application domains where TOLTEC has been used, including process planning of cylindrical and prismatic parts, design checking, material selection, and design of communications systems. >

Augmented transition networks as video browsing models for multimedia databases and multimedia information systems

In an interactive multimedia information system, users should have the flexibility to browse and choose various scenarios they want to see. This means that two-way communications should be captured by the conceptual model. Digital video has gained increasing popularity in many multimedia applications. Instead of sequential access to the video contents, the structuring and modeling of video data so that users can quickly and easily browse and retrieve interesting materials has become an important issue in designing multimedia information systems. An abstract semantic model called the augmented transition network (ATN), which can model video data and user interactions, is proposed in this paper. An ATN and its subnetworks can model video data based on different granularities, such as scenes, shots and key frames. Multimedia input strings are used as inputs for ATNs. The details of how to use multimedia input strings to model video data are also discussed. Key frame selection is based on the temporal and spatial relations of semantic objects in each shot. These relations are captured from our proposed unsupervised video segmentation method, which considers the problem of partitioning each frame as a joint estimation of the partition and class parameter variables. Unlike existing semantic models, which only model multimedia presentation, multimedia database searching or browsing, ATNs together with multimedia input strings can model these three in one framework.

On the robustness of Dempster's rule of combination

It is demonstrated by example that Dempsters rule of combination is not robust when combining highly conflicting belief functions. It is shown that Shafers (1983) discounted belief functions also suffer from this lack of robustness with respect to small perturbations in the discount factor. A modified version of Dempsters rule is proposed to remedy this difficulty.<<ETX>>

Study of interval-valued belief combination with conflicting evidence

A novel mathematical procedure for combining conflicting evidence which is represented in the interval form is presented. A methodology to construct combination rules which obey a set of essential properties is proposed. The method is based on a geometric model. The authors compare results obtained from Dempsters rule, the interval Bayes rule, and the proposed combination rule with both conflicting and nonconflicting data, and show that the values generated by the proposed combining rule are in tune with the authors intuition.<<ETX>>