When a client submits a set of XPath queries to a XML database on a network, the set of answer sets sent back by the database may include redundancy in two ways: some elements may appear in more than one answer set, and some elements in some answer sets may be subelements of other elements in other (or the same) answer sets. Even when a client submits a single query, the answer can be self-redundant because some elements may be subelements of other elements in that answer. Therefore, sending those answers as they are is not optimal with respect to communication costs. In this paper, we propose a method of minimizing communication costs in XPath processing over networks. Given a single or a set of queries, we compute a minimal-size view set that can answer all the original queries. The database sends this view set to the client, and the client produces answers from it. We show algorithms for computing such a minimal view set for given queries. This view set is optimal; it only includes elements that appear in some of the final answers, and each element appears only once.
When a client submits a set of XPath queries to a XML database on a network, the set of answer sets sent back by the database may include redundancy in two ways: some elements may appear in more than one answer set, and some elements in some answer sets may be subelements of other elements in other (or the same) answer sets. Even when a client submits a single query, the answer can be self-redundant because some elements may be subelements of other elements in that answer. Therefore, sending those answers as they are is not optimal with respect to communication costs. In this paper, we propose a method of minimizing communication costs in XPath processing over networks. Given a single or a set of queries, we compute a minimal-size view set that can answer all the original queries. The database sends this view set to the client, and the client produces answers from it. We show algorithms for computing such a minimal view set for given queries. This view set is optimal; it only includes elements that appear in some of the final answers, and each element appears only once.
Construction materials in a shutdown nuclear power plant contain radio activated nickel and cobalt in iron alloys such as stainless steel. The separation of nickel and cobalt from the alloy is required to reduce storage volume of the activated materials. In order to obtain fundamental information on the separation of nickel and cobalt from the stainless steel, the extraction method by using metallic tin as a solvent was studied at 1,673 K. The following results have been obtained.By addition of tin and silicon to the stainless steel, phase separation to the metallic tin phase and the stainless steel phase dissolving silicon occurs, and the minimum mutual solubility between the two phases was obtained at 23 mass % Si in the stainless steel phase at 1,673 K. The distribution ratio of nickel in the tin to stainless steel phases decreases extremely from 0.5 to 0.05 with increasing silicon content from 10 to 23 mass% in the stainless steel phase while the distribution ratios of cobalt and iron represent almost 1/10 of the nickel value. The separation coefficient of nickel shows the minimum value of 8 at 23 mass % Si in the Fe-Si phase while cobalt exhibits almost 2 in the experimental composition region. Based on the experimental results, the extraction and separation process for nickel and cobalt by using metallic tin as a solvent is evaluated at 1,673 K.
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