Search

Take the data processing of the volt-ampere characteristic of diode experiments and the single slit Fresnel diffraction for example, this paper gives an introduction to Matlab in physical experiment processing. Compared with traditional experiment methods, the application of Matlab in experiment data processing can avoid the error effectively which caused by manual handling, and the Matlab method is simple to operate. While the simulation to single slit Fresnel diffraction gives a more precise study on the diffraction phenomenon of light.

Crawling the deep web often requires the selection of an appropriate set of queries so that they can cover most of the documents in the data source with low cost. This can be modeled as a set covering problem which has been extensively studied. The conventional set covering algorithms, however, do not work well when applied to deep web crawling due to various special features of this application domain. Typically, most set covering algorithms assume the uniform distribution of the elements being covered, while for deep web crawling, neither the sizes of documents nor the document frequencies of the queries is distributed uniformly. Instead, they follow the power law distribution. Hence, we have developed a new set covering algorithm that targets at web crawling. Compared to our previous deep web crawling method that uses a straightforward greedy set covering algorithm, it introduces weights into the greedy strategy. Our experiment carried out on a variety of corpora shows that this new method consistently outperforms its un-weighted version.

Query rewriting using views is a technique for answering a query that exploits a set of views instead of accessing the database relations directly. There are two categories of rewritings, i.e., equivalent rewritings using materialized views applied in query optimization, and maximally contained rewritings used mainly in data integration. Although maximally contained rewritings are acceptable in data integration, there are cases where an equivalent rewriting is desired. More importantly, the maximally contained rewriting is a union of contained queries, many of which are redundant. This paper gives an efficient algorithm to find a complete and equivalent rewriting that is a single conjunctive query. We prove that the algorithm is guaranteed to find all the complete and equivalent rewritings, and that the resulting rewriting is guaranteed to be an equivalent one without additional containment checking. We also show that our algorithm is much faster than others through complexity analysis and experimentation.

Web service search is an important problem in service oriented architecture that has attracted widespread attention from academia as well as industry. Web service searching can be performed by various stakeholders, in different situations, using different forms of queries. All those combinations result in radically different ways of implementation. Using a real world web service composition example, this paper describes when, what, and how to search web services from service assemblers’ point of view, where the semantics of web services are not explicitly described. This example outlines the approach to implement a web service broker that can recommend useful services to service assemblers.

Automated web service composition is one of the major promises of service-oriented architecture, where services can be discovered and composed dynamically and automatically. To investigate the methods for composite web service construction, we conducted an experiment on creating useful composite web services from real existing web services where semantic annotations are not available. The empirical study reveals the difficulties and research challenges in the discovery, invocation, and composition of web services. The automation of web service composition requires the inputs from both services providers and service consumers. Service providers need to develop high quality services in a disciplined and collaborative way, and service consumers need to be equipped with tools providing helps such as service discovery and matching.

XML Schema is becoming an indispensable component in developing web applications. With its widespread adoption and its web accessibility, XML Schema reuse is becoming imperative. To support XML Schema reuse, the first step is to develop mechanism to search for relevant XML Schemas over the web. This paper describes a XML Schema matching system that compares two XML Schemas. Our matching system can find accurate matches and scales to large XML Schemas with hundreds of elements. In this system, XML Schemas are modelled as labeled, unordered and rooted trees, and a new tree matching algorithm is developed. Compared with the tree edit-distance algorithm and other schema matching systems, it is faster and more suitable for XML Schema matching.

This paper describes a matching algorithm that can find accurate matches and scales to large XML Schemas with hundreds of nodes. We model XML Schemas as labeled, unordered and rooted trees, and turn the schema matching problem into a tree matching problem. We develop a tree matching algorithm based on the concept of Approximate Common Structures. Compared with the tree edit-distance algorithm and other Schema matching systems, our algorithm is faster and more suitable for large XML Schema matching.

Generalization is a fundamental operation of inductive inference. While first order syntactic generalization (anti-unification) is well understood, its various extensions are needed in applications. This paper discusses syntactic higher order generalization in a higher order language λ2[1]. Based on the application ordering, we proved the least general generalization exists and is unique up to renaming. An algorithm to compute the least general generalization is presented.

This paper discusses the generalization of definite Horn programs beyond the ordering of logical implication. Since the seminal paper on generalization of clauses based on θ subsumption, there are various extensions in this area. Especially in inductive logic programming(ILP), people are using various methods that approximate logical implication, such as inverse resolution(IR), relative least general generalization(RLGG), and inverse implication(II), to generalize clauses. However, a program is more general than another program does not necessarily mean that the former should logically imply the latter. At least in the context of inductive synthesis of logic programs, we observe that the set inclusion ordering on the success set of logic programs is a more useful notion of generalization.