Complex Data Objects Research Articles

Ultrasound synthetic aperture imaging: monostatic approach

An ultrasound synthetic aperture imaging method based on a monostatic approach was studied experimentally. The proposed synthetic aperture method offers good dynamical resolution along with fast numerical reconstruction. In this study complex object data were recorded coherently in a two-dimensional hologram using a 3.5 MHz single transducer with a fairly wide-angle beam. Image reconstruction which applies the wavefront backward propagation method and the near-field curvature compensation was performed numerically in a microcomputer using the spatial frequency domain. This approach allows an efficient use of the FFT-algorithms. Because of the simple and fast scanning scheme and the efficient reconstruction algorithms the method can be made real-time. The image quality of the proposed method was studied by evaluating the spatial and dynamical resolution in a waterbath and in a typical tissue-mimicking phantom. The lateral as well as the range resolution (-6 dB) were approximately 1 mm in the depth range of 30-100 mm. The dynamical resolution could be improved considerably when the beam width was made narrower. Although it resulted in a slightly reduced spatial resolution this compromise has to be done for better resolution of low-contrast targets such as cysts. The study showed that cysts as small as 2 mm by diameter could be resolved. >

Object store with Navigation accelerator

In any database system, storage management is the crucial issue in determining the overall system performance. In this paper, the requirements for the storage and management of complex data objects are analyzed and the main design issues are discussed. Then, an abstract model of the object store is defined, in terms of structures, views and operations. The architecture of a High Performance Object Store (HIPOS), is presented. It consists of three components: the File Manager, the Collection Manager and the Navigation Manager. The Navigation Manager is identified as the key component for efficiency of the object store. A new organization, called Navigation Index, is proposed in which the navigation is performed by computations based on the theory of simple continued fractions. The performance is studied thoroughly both in terms of the retrieval navigation and update. An analytical system is designed in order to quantify the advantages of the navigation index for a specific object store.

Transaction management in design databases

Conventional data base systems are not suitable for handling advanced applications encountered in engineering, such as CAD/CAM, CASE, CAE, and VLSI design. The data bases in such environments, also called design data bases, are characterized by the presence of many complex data objects denoted by a large number of small tables, as opposed to a few large tables encountered in conventional data bases. The transaction model used in tracking data bases for banking, inventory control, and other such applications use view serializability as the correctness criterion. While view serializability is appropriate for tracking data bases, it is unnecessarily restrictive for engineering data bases. We propose a transaction model that is suitable for accessing shared design data based on coserializability. The transaction model supports long-duration transactions with intermediate commit points. In addition to the conventional nested transaction hierarchy, the model allows for cooperation between nested design transactions needed in a design environment.

An Object‐Oriented Data Management Model for Numerical Analysis in Computer‐Aided Engineering

Abstract: This paper presents an object‐oriented data management model for numerical analysis in computer‐aided engineering. A data storage structure and an index system have been developed for complex data objects encountered in numerical analysis. As an example, the model is applied to the finite element analysis.

Equality testing for complex objects based on hashing

An important characteristic of many new data models is the capability of constructing complex data objects. These complex data objects usually include set valued attributes. The efficiency of the implementation of sets heavily depends on the efficiency of the equality operator. In this paper we present algorithms for testing equality of complex objects based on hashing. To evaluate the performance of the two proposed algorithms we made simulations varying the different parameters involved. The first algorithm is based on hash functions and the second is based on a linear ordering. Equality testing based on hashing is considerably better, expecially for large objects. Furthermore, equality testing based on a linear ordering requires preprocessing for maintaining the linear order, whereas in the other case the preprocessing consists solely of calculating the hash values.

Realizing a temporal complex-object data model

Support for temporal data continues to be a requirement posed by many applications such as VLSI design and CAD, but also in conventional applications like banking and sales. Furthermore, the strong demand for complex-object support is known as an inherent fact in design applications, and also emerges for advance “conventional” applications. Thus, new advanced database management systems should include both features, i.e. should support temporal complex-objects . In this paper, we present such a temporal complex-object data model. The central notion of our temporal complex-object data model is a time slice , representing one state of a complex object. We explain the mapping of time slices onto the complex objects supported by the MAD model (which we use for an example of a non-temporal complex-object data model) as well as the transformation process of operations on temporal complex-objects into MAD model operations. Thereby, the basic properties of the MAD model are a prerequisite for our approach. For example, time slices can only be directly stored, if non-disjunct (i.e. over-lapping) complex objects are easily handled in the underlying complex-object data model.

Deductive-ER: deductive entity-relationship data model and its data language

The entity-relationship (ER) data model is a well known semantic data model in database design. The paper develops a deductive-ER data model, Deductive-ER, which applies the ER approach to the design of deductive databases. Based on such a model, a deductive-ER data language, called Deductive-ER, is constructed, which provides capabilities of definition and manipulation of extensional database components, intensional database components (including virtual entities, virtual relationships, and virtual attributes), hybrid components, generalization hierarchies, and integrity constraints. It supports complex data objects, including tuple-valued, list-valued, text-valued, set-valued, and null-valued attributes. Moreover, it allows recursive definitions. Deductive-ER integrates two different flavoured languages: an ER-based conventional data language and a Horn-clause-based logic data language. It takes advantage of both and provides a simple and powerful interface. The implementation of Deductive-ER is also discussed.

Object-oriented databases and their impact on future business database applications

The relational data model cannot handle the increasingly complex data management requirements imposed by many of today's applications. The object-oriented database concept provides greater capabilities through the support of user defined abstract data types, complex data objects that may contain other objects, procedural attachment to attributes, inheritance, and a more flexible means of deriving values and representing constraints. Existing object-oriented development projects, besides developing systems from scratch, are extending relational systems to include user defined data types or expanding object-oriented languages to allow storage of complex objects on mass storage devices. They are, however, still evolving. An application involving product configuration and sales quotation generation is presented. It illustrates the advantages of using the object-oriented approach.

Data‐Base Management System Technology and Geographic Information Systems

Current operational data-base management system technology is restrictive in its capacity to clearly model and efficiently manage complex data objects, in general, and spatial data objects, such as those handled by geographic information system (GIS) software, in particular. This has led to the prevalence of hybrid GIS software architectures, in which the lexical and geometric components of spatial data are managed in a disintegrated fashion. However, recent developments in object-oriented DBMS technology suggest approaches for the unified management of spatial data. The need for distributed management of spatial data poses further technological challenges. Structure transfer protocols must be further developed to support real-time interchanges of subsets of spatial database on a query-by-query basis. Distributed crash recovery, concurrency control, and multiple copy updated capabilities as developed for distributed relational data bases must also be provided for distributed object-oriented data bases. Also, the technology to support physical and semantic integration needs to be further developed to allow distributed GISs to be built from pre-existing single-site components.

Recursive functions in a data base language for complex objects

The work presented in this paper demonstrates a new method for recursive queries in a complex object data base system. The method is called functional recursion. Most previous approaches express recursive queries by set oriented recursion, i.e. they allow us to define a set M recursively by an equation M = ƒ(M). In contrast to set oriented recursion, functional recursion as defined in this paper allows the user to define a function ƒ recursively by an equation ƒ = F(ƒ). As opposed to recursive functions written in a conventional programming language, the termination criterion which sometimes is rather complex does not have to be programmed by the user but is given implicitly. By providing appropriate parameters to a function, the user can integrate a selection into the recursion in a convenient and natural way. This is not the case for set oriented recursion. When using set recursion, the user is forced to formulate a query which computes more than really needed. It is the task of the optimizer then to push the subsequent selection into the recursion. This means that the user cannot write the query in a natural way and the system then has to figure out what the user wanted. All these problems are avoided when using recursive functions as defined in this paper. Moreover, a solution based on key oriented duplicate elimination is presented which solves the problem of lists and arithmetics in the context of recursive functions. The method is illustrated by bill-of-materials examples and by a railroad example.

Object identity as a query language primitive

We demonstrate the power of object identities (oid's) as a database query language primitive. We develop an object-based data model, whose structural part generalizes most of the known complex-object data models: cyclicity is allowed in both its schemas and instances. Our main contribution is the operational part of the data model, the query language IQL, which uses oid's for three critical purposes: (1) to represent data-structures with sharing and cycles, (2) to manipulate sets and (3) to express any computable database query. IQL can be statically type checked, can be evaluated bottom-up and naturally generalizes most popular rule-based database languages. The model can also be extended to incorporate type inheritance, without changes to IQL. Finally, we investigate an analogous value-based data model, whose structural part is founded on regular infinite trees and whose operational part is IQL.

An input/output primitive for object-oriented systems

This paper describes an input/output primitive based on the concept of region hierarchies, which allows highly-structures images of simple or complex data objects to be constructed in a straightforward fashion. In addition, any image of a data object may represent a hierarchical menu which provides access to the operations associated with the object. The programmer is not required to manage the details of an image at the level of the coordinates of the image elements and support is naturally provided for a screen/mouse pair as a fundamental input/output device. Keyboards, clocks and other devices can be supported as special cases. The primitive may be extended to support multidimensional representations and time-ordered sequences. Applications of the latter facility include animation and speech generation.

A recursive approach to office object modelling

Office modelling aims at providing abstract, conceptual tools for describing office semantics in order to ease high-level and are more likely to correct application programming. Advanced office systems are complex organizations of objects, procedures, activities, locations, etc., incorporating independent user workstations with which people cooperate in executing complicated office tasks. Office information systems support the representation, storage, access and maintenance of complex data objects occurring frequently in office environments. Based on the structural aspects of such office objects, we provide language constructs to model office procedures which are perceived as being based on the following semantic primitives: complex data object constructors that accept object components (e.g., addresses, dates, text-fragments) and return office objects of composite type (e.g., letters, forms, memos), component selectors that select specific object components from composite data objects, and operations for recognizing the type of a given complex data object. We gain our language constructs by generalizing the corresponding solutions provided by conventional, record-based database models. This leads us from the ‘flat structures’ of traditional database models to ‘recursive structures’ allowing for flexible representations of non-formatted and highly related data as required for advanced office object modelling.

A Framework for data structurest†

In this paper we outline a framework for data structures in the spirit of the Vienna Definition Language but extended to the most general class of objects, namely arbitrary directed rooted graphs in which the information asociated with each node is either empty or elementrary or an object in the general class. Since many data structures cannot be modelled by tree structures in a natural way, such a generalisation to graphs is desirable. Furthermore, the concept of hierarchy in which a node may serve for a arbitrary complex substructure supports a structured view of complex data objects.

On an improvement in the art of galvanizing

Data mining is the discovery of knowledge and useful information from the large amounts of data stored in databases. With the increasing popularity of object-oriented database systems in advanced database applications, it is important to study the data mining methods for object-oriented databases because mining knowledge from such databases may improve understanding, organization, and utilization of the data stored there. In this paper, issues on generalization-based data mining in object-oriented databases are investigated in three aspects: (1) generalization of complex objects, (2) class-based generalization, and (3) extraction of different kinds of rules. An object cube model is proposed for class-based generalization, on-line analytical processing, and data mining. The study shows that (i) a set of sophisticated generalization operators can be constructed for generalization of complex data objects, (ii) a dimension-based class generalization mechanism can be developed for object cube construction, and (iii) sophisticated rule formation methods can be developed for extraction of different kinds of knowledge from data, including characteristic rules, discriminant rules, association rules, and classification rules. Furthermore, the application of such discovered knowledge may substantially enhance the power and flexibility of browsing databases, organizing databases and querying data and knowledge in object-oriented databases.