Phase transition behavior and electrical properties of lead-free (1-x)KNLNS-xBNKZ piezoelectric ceramics

Lead-free (1-x)(K_0,48Na_0,48Li_0,04)(Nb_0,95Sb_0,05)O₃-xBi_0.5(Na_0.82K_0.18)_0.5ZrO₃ (KNLNS-xBNKZ) piezoelectric ceramics (x?=?0, 0.02, 0.04, 0.06, 0.08, and 0.1) were successfully prepared by the two-step sintering method. The effects of different BNKZ contents on the crystal structure, ferroelectric phase transition, and electrical properties of the as-prepared ceramics were systematically researched. The ceramics with a perovskite structure possessed an orthorhombic phase (space group?=?Amm2) at x?=?0, a mixed orthorhombic-tetragonal phase (Amm2?+?P4/mbm) at x?=?0.02, a mixed rhombohedral-tetragonal (R-T) phase (R3m?+?P4/mbm) at x?=?0.04–0.06, and a rhombohedral phase (R3m) at x>0.06. At x?=?0.04 (rhombohedral and tetragonal (R-T) phases coexisted), the ceramics manifested the best electrical properties with d₃₃?=?224 pC/N, k_p = 0.44, k_t = 0.47, T_C = 218^oC, and remanent polarization (P_r)?=?11.5µC/cm². The improvement of the electrical properties of KNLNS-BNKZ ceramics was achieved by controlling their phase compositions and microstructures.

     

The roles of artificial intelligence in information systems

By classifying information processing tasks which are suitable for artificial intelligence approaches we determine an architectural structure for large systems. We visualize a three-layer architecture of private applications, mediating information servers, and an infrastructure which provides information resources.The base information resources are likely to use algorithmic techniques, since they will deal with many similar base objects. Their results are at higher level of abstraction, diverse, and fewer in number. The information servers must consider the scope, assumptions, and meaning of those intermediate results. Such processing will require techniques grounded in artificial intelligence concepts. Applications will need artificial intelligence techniques to augment the human interface and provide high-level decision support.Information processing in the intermediate layer is domain-specific and a module is constrained to a single ontology. Processing here is comprised of search and control of search, focusing, pruning, fusion, and other means of data reduction. There are also control tasks associated with effective resource management. Their results are then composable by higher-level applications, which have to solve problems involving multiple subtasks.The architecture presented here is a generalization of a server-client model. The mediating server modules will need a machine-friendly interface to support the application layer. The partitioning enhances maintainability, but raises questions of effectiveness and efficiency.Without new and composable structures we will be stuck with a mixture of obsolete large systems and isolated new applications. A formal partitioning provides a model where subproblems become accessible to research. Interoperation is now a distinct source of research problems. We identify some of these issues, and hope that composability of solutions will permit progress in building effective large systems.This paper is substantially based on [50] and [51]. I thank both the original and recent reviewers and listeners for feedback received on this material. Further comments were given by Marianne Siroker and Maria Zemankova.     

Efficiently instantiating view-objects from remote relational databases

View-objects are complex objects that are instantiated by delivering a query to a database and converting the query result into a nested structure. In relational databases, query results are conventionally retrieved as a single flat relation, which contains duplicate subtuples in its composite tuples. These duplicate subtuples increase the amount of data to be handled and thus degrade performance. In this article, we describe two new methods that retrieve a query result in structures other than a single flat relation. One method retrieves a set of relation fragments, and the other retrieves a single-nested relation. We first describe their algorithms and cost models, and then present the cost comparison results in a client-server architecture with a relational main memory database residing on a server.     

Engineering Information Service Infrastructure for Ubiquitous Computing

This paper describes a software framework for the development of a ubiquitous computing environment for distributed engineering information services. Two fundamental issues are addressed: universal accessibility of devices to information services, and collaboration among the parties accessing the information services. The first calls for the development of device-independent information services that have the flexibility to support a wide range of client devices. We introduce a mediation-based framework that enables information clients to calibrate the source information services to the clients’ characteristics. The second requires effective integration of information services, which we address in two ways: (1) we sketch an ontology standard and describe how such a standard can be effectively applied for exchanging project scheduling and resource information; and (2) we illustrate an infrastructure that is particularly suitable for the integration of engineering services. A prototype for the ubiquitous computing environment has been developed that incorporates a variety of project management software as well as different devices ranging from PDAs to Web browsers, desktop computers, and servers.     

Management of complex structural engineering objects in a relational framework

To structure the development of an integrated building design environment, the global representation of the design data may best be organized in terms of hierarchies of objects. In structural engineering design we deal with large sets of independent but interrelated objects. These objects are specified by data. For an engineering design data base the system must be able to model the objects composing the design as well as to manage effectively the design data. The data base management system therefore needs to have some knowledge of the intended use of the data, and must provide an abstraction mechanism to represent and manipulate objects. Much recent research in engineering data bases focuses on object management for specific tasks but gives little attention to the shareability of the underlying information. This paper describes an architecture for the management of complex engineering objects in a sharable, relational framework. Potential application of this approach to object management for structural engineering analysis and design is discussed.     

Content-based image indexing and searching using Daubechies' wavelets

This paper describes WBIIS (Wavelet-Based Image Indexing and Searching), a new image indexing and retrieval algorithm with partial sketch image searching capability for large image databases. The algorithm characterizes the color variations over the spatial extent of the image in a manner that provides semantically meaningful image comparisons. The indexing algorithm applies a Daubechies' wavelet transform for each of the three opponent color components. The wavelet coefficients in the lowest few frequency bands, and their variances, are stored as feature vectors. To speed up retrieval, a two-step procedure is used that first does a crude selection based on the variances, and then refines the search by performing a feature vector match between the selected images and the query. For better accuracy in searching, two-level multiresolution matching may also be used. Masks are used for partial-sketch queries. This technique performs much better in capturing coherence of image, object granularity, local color/texture, and bias avoidance than traditional color layout algorithms. WBIIS is much faster and more accurate than traditional algorithms. When tested on a database of more than 10 000 general-purpose images, the best 100 matches were found in 3.3 seconds.     

Information Systems that Really Support Decision-Making

Decision makers are expected to make decisions which have a positive effect on the future of their enterprises. We expect that intelligent information systems support their activities. Today, databases and web-based resources, accessed through effective communications, make information about the past rapidly available. To project the future the decision makers either have to use intuition or employ tool for prediction, and initialize such tools with information obtained from an information system to such tools. An effective information system should integrate forecasting the future, and because there choices have been made, such a system must also support the comparative assessment of the effects of alternate decisions. The complexity of an information system handling the past, and multiple futures will be great, and must be modularized with effective interfaces. We recommend the use of an SQL-like interface language to access existing tools to assess the future, as spreadsheets and simulations. Making results of simulations accessible as another contribution to integrated information systems has the potential of greatly augmenting their effectiveness and really support decision-making.     

A branch, bound, and remember algorithm for the 1|r i |∑t i scheduling problem

This paper presents a modified Branch and Bound (B&B) algorithm called, the Branch, Bound, and Remember (BB&R) algorithm, which uses the Distributed Best First Search (DBFS) exploration strategy for solving the 1|r _i |∑t _i scheduling problem, a single machine scheduling problem where the objective is to find a schedule with the minimum total tardiness. Memory-based dominance strategies are incorporated into the BB&R algorithm. In addition, a modified memory-based dynamic programming algorithm is also introduced to efficiently compute lower bounds for the 1|r _i |∑t _i scheduling problem. Computational results are reported, which shows that the BB&R algorithm with the DBFS exploration strategy outperforms the best known algorithms reported in the literature.