Branch-and-bound processing of ranked queries

Despite the importance of ranked queries in numerous applications involving multi-criteria decision making, they are not efficiently supported by traditional database systems. In this paper, we propose a simple yet powerful technique for processing such queries based on multi-dimensional access methods and branch-and-bound search. The advantages of the proposed methodology are: (i) it is space efficient, requiring only a single index on the given relation (storing each tuple at most once), (ii) it achieves significant (i.e., orders of magnitude) performance gains with respect to the current state-of-the-art, (iii) it can efficiently handle data updates, and (iv) it is applicable to other important variations of ranked search (including the support for non-monotone preference functions), at no extra space overhead. We confirm the superiority of the proposed methods with a detailed experimental study.     

Significance of formation factor in sand structure characterization

The formation factor F, obtained by electrical conductivity measurements of saturated sand samples, has been recently correlated with the liquefaction behavior of sands (2). The significance of F as a parameter obtained by nondestructive technique is discussed here, showing its capability to characterize the structure of anisotropic sand aggregates.     

Multi-Way Distance Join Queries in Spatial Databases

Let a tuple of n objects obeying a query graph (QG) be called the n-tuple. The D_{_distance}-value of this n-tuple is the value of a linear function of distances of the n objects that make up this n-tuple, according to the edges of the QG. This paper addresses the problem of finding the K n-tuples between n spatial datasets that have the smallest D_{_distance}-values, the so-called K-multi-way distance join query (K-MWDJQ), where each set is indexed by an R-tree-based structure. This query can be viewed as an extension of K-closest-pairs query (K-CPQ) [8] for n inputs. In addition, a recursive non-incremental branch-and-bound algorithm following a depth-first search for processing synchronously all inputs without producing any intermediate result is proposed. Enhanced pruning techniques are also applied to n R-trees nodes in order to reduce the total response time and the number of distance computations of the query. Due to the exponential nature of the problem, we also propose a time-based approximate version of the recursive algorithm that combines approximation techniques to adjust the quality of the result and the global processing time. Finally, we give a detailed experimental study of the proposed algorithms using real spatial datasets, highlighting their performance and the quality of the approximate results.     

Rule-based query personalization in digital libraries

Searching a digital library is typically a tedious task. A system can improve information access by building on knowledge about a user acquired in a user profile in order to customize information access both in terms of the information returned in response to a query (query personalization) as well as in terms of the presentation of the results (presentation personalization). In this paper, we focus on query personalization in digital libraries; in particular, we address structured queries involving metadata stored in relational databases. We describe the specification of user preferences at the level of a user profile and the process of query personalization with the use of query-rewriting rules.     

A unified interaction scheme for information sources

Commonly, for retrieving the desired information from an information source (knowledge base or information base), the user has to use the query language that is provided by the system. This is a big barrier for many ordinary users and the resulting interaction style is rather inflexible. In this paper we give the theoretical foundations of an interaction scheme that allows users to retrieve the objects of interest without having to be familiar with the conceptual schema of the source or with the supported query language. Specifically, we describe an interaction manager that provides a quite flexible interaction scheme by unifying several well-known interaction schemes. Furthermore, we show how this scheme can be applied to taxonomy-based sources by providing all needed algorithms and reporting their computational complexity.     

Thermal effects on the enhanced ductility in non-monotonic uniaxial tension of DP780 steel sheet

To understand the material behavior during non-monotonic loading, uniaxial tension tests were conducted in three modes, namely, the monotonic loading, loading with periodic relaxation and periodic loading-unloadingreloading, at different strain rates (0.001/s to 0.01/s). In this study, the temperature gradient developing during each test and its contribution to increasing the apparent ductility of DP780 steel sheets were considered. In order to assess the influence of temperature, isothermal uniaxial tension tests were also performed at three temperatures (298 K, 313 K and 328 K (25 °C, 40 °C and 55 °C)). A digital image correlation system coupled with an infrared thermography was used in the experiments. The results show that the non-monotonic loading modes increased the apparent ductility of the specimens. It was observed that compared with the monotonic loading, the temperature gradient became more uniform when a non-monotonic loading was applied.     

Digital Cities: Towards an integrated decision support methodology

This paper deals with the problem of the low ICT adoption rate by many cities or urban regions. The consequences of the poor ICT environment in these authorities may be summarized into (i) the cutback of local business competitiveness, (ii) the incapability of attracting new business investments, (iii) the poor service of citizens needs (living in the local area or abroad – a foreign country or another city, namely emigrants), (iv) the poor service of visitors that have or want to have transactions in the local area. The main shortcomings of local authorities refer to lack of capabilities and expertise, negligence of local needs and urban characteristics, absence of ICT adoption models to local needs, ignorance of development and exploitation models etc. These regions need support so as to select the most appropriate ICT best practices, integrated them into their strategic plans and implement them with success. This procedure is particularly complex, since many factors and restrictions have to be considered. The overall objective of this paper is to illustrate the Digital City concept and to propose an integrated methodology for Digital City development that will act in a supportive way for the regions or cities that have low rates in ICT penetration and try to adopt ICT best practices into their core functions and services.     

Numerical evaluation of droplet sizing based on the ratio of fluorescent and scattered light intensities (LIF/Mie technique)

The dependence of fluorescent and scattered light intensities from spherical droplets on droplet diameter was evaluated using Mie theory. The emphasis is on the evaluation of droplet sizing, based on the ratio of laser-induced fluorescence and scattered light intensities (LIF/Mie technique). A parametric study is presented, which includes the effects of scattering angle, the real part of the refractive index and the dye concentration in the liquid (determining the imaginary part of the refractive index). The assumption that the fluorescent and scattered light intensities are proportional to the volume and surface area of the droplets for accurate sizing measurements is not generally valid. More accurate sizing measurements can be performed with minimal dye concentration in the liquid and by collecting light at a scattering angle of 60° rather than the commonly used angle of 90°. Unfavorable to the sizing accuracy are oscillations of the scattered light intensity with droplet diameter that are profound at the sidescatter direction (90°) and for droplets with refractive indices around 1.4.     

Method to reduce errors of droplet sizing based on the ratio of fluorescent and scattered light intensities (laser-induced fluorescence/Mie technique)

The droplet sizing accuracy of the laser technique, based on the ratio of laser-induced fluorescence (LIF) and scattered light (Mie) intensities from droplets, is examined. We develop an analytical model of the ratio of fluorescent to scattered light intensities of droplets, which shows that the LIF/Mie technique is susceptible to sizing errors that depend on the mean droplet size and the spread of the droplet size distribution. The sizing uncertainty due to the oscillations of the scattered light intensity as a function of droplet size is first quantified. Then, a new data processing method is proposed that can improve the sizing uncertainty of the technique for the sprays that were examined in this study by more than 5% by accounting for the size spread of the measured droplets, while improvements of 25% are possible when accounting for the mean droplet size. The sizing accuracy of the technique is evaluated in terms of the refractive index of liquid, scattering angle, and dye concentration in the liquid. It is found that the proposed approach leads to sizing uncertainty of less than 14% when combined with light collection at forward scattering angles close to 60° and the lowest fluorescent dye concentration in the liquid for all refractive indices.     

CRITICAL REVIEW ON THE ANALYTICAL METHODS FOR THE DETERMINATION OF ZWITTERIONIC ANTIEPILEPTIC DRUGS—VIGABATRIN,PREGABALIN, AND GABAPENTIN—IN BULK AND FORMULATIONS

Drugs with antiepileptic activity constitute a group of heterogeneous compounds and therefore their determination cannot follow a universal procedure. Among them, vigabatrin, pregabalin, and gabapentin are of similar nature, due to their zwitterionic structure. This structure enables similar approaches for their determination, including derivatization protocols. This article presents a thorough survey on published methods for the determination of this subgroup of antiepileptic compounds in bulk and pharmaceutical preparations. Spectrophotometric and spectrofluorimetric methods, with or without derivatization reagents, as thin-layer chromatography, high-performance liquid chromatography with various detectors, gas chromatography, capillary electrophoresis, infrared, and potentiometric methods, have been extensively applied for these compounds, providing reliable results. Additionally, the number of citations and purpose for each method were discussed with critical commentary.