Bipolar querying of valid-time intervals subject to uncertainty

Databases model parts of reality by containing data representing properties of real-world objects or concepts. Often, some of these properties are time-related. Thus, databases often contain data representing time-related information. However, as they may be produced by humans, such data or information may contain imperfections like uncertainties. An important purpose of databases is to allow their data to be queried, to allow access to the information these data represent. Users may do this using queries, in which they describe their preferences concerning the data they are (not) interested in. Because users may have both positive and negative such preferences, they may want to query databases in a bipolar way. Such preferences may also have a temporal nature, but, traditionally, temporal query conditions are handled specifically. In this paper, a novel technique is presented to query a valid-time relation containing uncertain valid-time data in a bipolar way, which allows the query to have a single bipolar temporal query condition

Ketterien menetelmien käyttö tietovarastoinnissa

Tämän opinnäytetyön tavoitteena on selvittää, miten hyvin toimeksiantajayrityksessä hyödynnetään ketteriä menetelmiä osana tietovarastointia. Toisena tavoitteena on löytää mahdollisia kehityskohteita toimeksiantajan käyttämissä menetelmissä. Opinnäytetyön toimeksiantajayritys on ottanut ketterät menetelmät käyttöön osana tietovarastointia kuusi kuukautta ennen opinnäytetyön aloittamista. Työn teoriaosa käsittelee tietovarastointia ja keskittyy ketteristä menetelmistä Scrumviitekehykseen ja tietovarastoinnin tuomiin haasteisiin menetelmien käytössä. Teoriaosuuden lähteinä on käytetty laajasti ketteriä menetelmiä ja tietovarastointia käsitteleviä teoksia, sekä erityisesti tietovarastoinnin kannalta ketteriin menetelmiin keskittyneitä teoksia. Empiirinen osa koostui tietovarastointiprosessiin osallistumisesta kehittäjän roolissa. Tutkimuksessa toteutettiin ETL-prosessi käyttäen ketteriä menetelmiä ja kuvataan yrityksessä käytettyjä menetelmiä. Tutkimuksessa saatuja kokemuksia peilataan teoreettiseen viitekehykseen kehityskohteiden löytämiseksi. Tutkimuksen aikana toteutettiin ETL-prosessi asetetuissa aikataulutavoitteissa käyttäen ketteriä menetelmiä. Tutkimuksen pohjalta saatiin kattavasti tuloksia ketterien menetelmien sopivuudesta tietovarastointiin. Tulosten pohjalta pystyttiin esittämään toimeksiantajayritykselle kehitysideoita ja asioita, joihin tulisi kiinnittää erityisesti huomiota.The aim of this bachelor’s thesis is to find out how agile methods have been adapted to this thesis client’s data warehousing process. The second aim is to find out possible ways to improve the used agile methods. The client of the thesis has started using agile methods in the autumn of 2015. The theoretical part of the thesis introduces the concept of data warehousing and agile methods. In addition, the theoretical section of the thesis concentrates on the Scrum framework and introduces characteristics of agile data warehousing. The empirical section of this thesis is based on taking part in the client’s data warehousing process as a developer. The empirical section includes the description of the Extract – Transform – Load (ETL) process carried out with using agile methods and common description of client’s agile methods. Findings made during study are used along with the theoretical framework to find out possible areas for improvement. The ETL -process was completed successfully achieving the given goals. The case study provided good evidence about how agile methods are suitable for data warehousing projects. Several areas for improvement possibilities were came up in the client’s agile methods

Capturing Uncertainty in Spatial Queries over Imprecise Data

Emerging applications using miniature electronic devices (e.g., tracking mobile objects using sensors) generate very large amounts of highly dynamic data that poses very high overhead on databases both in terms of processing and communication costs. A promising approach to alleviate the resulting problems is to exploit the application's tolerance to bounded error in data in order to reduce the overheads. In this paper, we consider imprecise spatial data and the correlation between the data quality and precision requirements given in user queries. We first provide an approach to answer spatial range queries over imprecise data by associating a probability value with each returned object. Then, we present a novel technique to set the data precision constraints for the data collecting process, so that a probabilistic guarantee on the uncertainty in answers to user queries could be provided. The algorithms exploit the fact that objects in two-dimensional space are distributed under certain distribution function. Experimental results are also included

A comparative evaluation of dimensional stability of three types of interocclusal recording materials-an in-vitro multi-centre study

<p>Abstract</p> <p>Background</p> <p>The introduction of different interocclusal recording materials has put clinicians in dilemma that which material should be used in routine clinical practice for precise recording and transferring of accurate existing occlusal records for articulation of patient’s diagnostic or working casts in the fabrication of good satisfactory prosthesis. In the era of developing world of dentistry the different materials are introduced for interocclusal record with different brand names because of this; the utility of the material is confusing for successful delivery of prosthesis with lack of in vitro or in vivo studies which will predict the property of the material with utility recommendations.</p> <p>Purpose of the study</p> <p>The aim of this multicenter research is to evaluate the time dependent linear dimensional stability of three types of interocclusal recording materials; which gives very clear idea to clinicians in regard to its usage in routine practice and recommendations for usage of the different materials. Also to find out ideal time for articulation of three types of interocclusal recording materials with accuracy.</p> <p>Materials and method</p> <p>Commercially available and ADA approved Polyether bite registration paste (Ramitec), Poly vinyl siloxane bite registration paste (Jetbite) and Zinc oxide eugenol (ZOE) bite registration paste (Super bite) were used in the study.</p> <p>A stainless steel die was made according to modified American dental Associations (ADA) specification no. 19. Each one of the tested materials were manipulated according to manufacturers’ instructions. The materials separated from die, 3-mins after their respective setting time, resulted in disks of standard diameter. Two parallel lines and three perpendicular lines reproduced on the surface. The distance between two parallel lines was measured at different time intervals i.e. 1 hour, 24, 48 and 72 hours by using travelling microscope (magnus) and compared with standard die measurements made according to ADA specification no.19 to find out the dimensional stability of these interocclusal recording materials. Total 120 samples were made for observation and results were subjected to statistical analysis. Statistical analysis was performed using analysis of variance (ANOVA) and then Tukey’s Honestly Significant Difference (HSD) test for comparison among groups at the 0.05 level of significance. After statistical analysis of the data, results were obtained and analyzed for interpretation.</p> <p>Results</p> <p>The results shows significant difference between the dimensional stability of all three material at different intervals with p-value <0.05. Comparatively the polyether bite registration material showed less distortion with good dimensional stability compared to Poly vinyl siloxane bite (Jetbite), Zinc oxide eugenol(ZOE) bite (Super bite) at 1 hour, 24, 48, and 72 hours.</p> <p>Conclusion</p> <p>The dimensional stability decreased with increase in time and is influenced by both material factor and time factor. Polyether was found to be more dimensionally stable interocclusal recording material, which was followed by Silicone and Zinc oxide eugenol (ZOE). The dimensional stability of Polyether was good. Zinc oxide eugenol is dimensionally more unstable when compared with polyether and polyvinyl siloxane. We recommend that the polyether interocclusal records must be articulated within 48 hours and Polyvinylsiloxane interocclusal records must be articulated within 24 hours and the ZOE should be articulated within 1 hour to get a correct restoration to have very minimum distortion and maximum satisfaction without failure of prosthesis.</p