Vitaly A. Semenov

Visualization in string theory

Abstract The tools for visualization of relativistic string dynamics in various topological classes are developed. New theoretical results, obtained with the aid of these tools, are described.

On complementary principles of object-oriented constraint programming

The paper is devoted to the implementation of the paradigm of the object-oriented constraint programming (OOCP), which combines complementary ideas and principles of the object-oriented programming (OOP) and constraint logical programming (CLP). Although the idea looks attractive and there have been attempts to implement it with the use of logical and functional languages, its future outline is still not clear. In the paper, a survey of the existing technologies of the constraint programming is given, and a new systematic approach to the implementation of the object-oriented constraint programming based on the use of declarative data modeling languages is discussed. The advantages of the approach related to the expressiveness and generality of the constraint problem declarations are demonstrated on the example of the classical mathematical queen problem. A general algorithmic strategy of solving the constraint problems is also discussed.

Semantics-based Reconciliation of Divergent Replicas in Advanced Concurrent Engineering Environments

A novel method for semantics-based reconciliation of long-lived transactions in concurrent engineering environments is described. The reconciliation is a key element of recent optimistic replication technologies facing the challenges of diverging replicas, conflicts between concurrent operations and disturbing consistency. The research presented addresses the general problem of semantically consistent and functionally meaningful reconciliation and enables significant simplification and formalization of its solution. The advantages of the method are strong guarantees of semantic consistency of the convergent representation, capabilities to use it in autonomous and user interactive modes as well as avoidance of combinatorial explosion peculiar to many other methods. The particular application is presented to illustrate how the method can be effectively applied for collaborative software engineering in the scope of the emerging UML-driven methodology.

An object-oriented architecture for applications of scientific visualization and mathematical modeling

Issues of the general architecture design for integrated applications of mathematical modeling and scientific visualization are considered. In line with the object-oriented methodologies of Bailin and Booch, a novel model for a visualization scene is described. The scene is a composition of interrelated, typed scientific data and algorithms. A systematic approach to developing applications based on the model is presented. Theoretical analysis is illustrated by various examples related to geometric modeling, numerical solution of ordinary differential equations, visualization, and rendering.

Methods of spatial indexing of dynamic scenes based on regular octrees

The paper is devoted to study and development of spatial indexing methods as applied to three dimensional scenes arising in computer graphics, CAD/CAM systems, robotics, virtual and augmented reality applications, nD-modeling systems, and in project planning. Such scenes are compositions of a great number of extended geometrical objects exhibiting individual dynamic behaviors. The main focus is placed on algorithms for executing typical spatial queries with the use of regular dynamic octrees. In particular, algorithms for determining collisions, region search and nearest neighbor search are studied. For the model datasets introduced, average complexity estimates of index construction and execution of typical queries are derived based on probabilistic analysis. The estimates obtained significantly improve known pessimistic results and justify the suitability of regular octrees to spatial indexing of large-scale dynamic scenes. Results of computational experiments substantiate theoretical results and demonstrate possibilities of creating efficient computer graphics applications under the condition of permanently growing complexity of visual models.

Indexing of Hierarchically Organized Spatial-Temporal Data Using Dynamic Regular Octrees

The paper is devoted to theoretical and experimental study of indexing methods as applied to spatial-temporal datasets appearing in different science and industry domains. For this purpose a general spatial-temporal data model is presented as a scene that admits hierarchically organized, heterogeneous spatial objects with individual temporal behaviors. For the model presented we argue the relevance of dynamic event-driven regular octrees as an underlying spatial-temporal indexing structure to a wide class of applications and prove its effectiveness for queries such as scene reconstruction, region search, and collision detection.

Concurrent Planning Using Semantics-driven Reconciliation

Concurrent planning, scheduling, and monitoring are challenging problems relating to effective communication and collaboration among key project participants like managers, planners, designers, cost analysts, and production engineers. Commercially available planning systems provide for a wide range of traditional network techniques such as Gantt chart, Critical Path Method (CPM), and the Program Evaluation and Review Technique (PERT), but have significant limitations for large-scale projects which have to be managed concurrently due to complexity and short deadlines. Being oriented on synchronously working users, such systems usually adopt client-server architectures, centralized data stores and pessimistic transaction models that create well-known performance, availability and productivity shortcomings. The research presented follows alternative approach to collaborative planning based on optimistic replication of project data and use of all-embracing, semantics-driven reconciliation method (SRM). The method enables to identify and to resolve conflicts in concurrently elaborated plans and bring them to semantically correct representation. Being implemented as a data exchange bridge between project management and 4D modelling systems, it supports effective collaboration through synchronizing the project plans and consolidating the results of individual work.