The Design of Very Fast Portable Compilers

The Amsterdam Compiler Kit is a widely used compiler building system. Up until now, the emphasis has been on producing good object code. In this paper we describe recent work that has focused on reducing compile time. The techniques described in this paper have resulted in C compilers for the Sun-3 and VAX that are 3 to 4 times faster than the native compilers provided by the manufacturers. 1

DynamiTE: Parallel Materialization of Dynamic RDF Data

One of the main advantages of using semantically annotated data is that machines can reason on it, deriving implicit knowledge from explicit information. In this context, materializing every possible implicit derivation from a given input can be computationally expensive, especially when considering large data volumes. Most of the solutions that address this problem rely on the assumption that the information is static, i.e., that it does not change, or changes very infrequently. However, the Web is extremely dynamic: online newspapers, blogs, social networks, etc., are frequently changed so that outdated information is removed and replaced with fresh data. This demands for a materialization that is not only scalable, but also reactive to changes. In this paper, we consider the problem of incremental materialization, that is, how to update the materialized derivations when new data is added or removed. To this purpose, we consider the ρdf RDFS fragment [12], and present a parallel system that implements a number of algorithms to quickly recalculate the derivation. In case new data is added, our system uses a parallel version of the well-known semi-naive evaluation of Datalog. In case of removals, we have implemented two algorithms, one based on previous theoretical work, and another one that is more efficient since it does not require a complete scan of the input. We have evaluated the performance using a prototype system called DynamiTE, which organizes the knowledge bases with a number of indices to facilitate the query process and exploits parallelism to improve the performance. The results show that our methods are indeed capable to recalculate the derivation in a short time, opening the door to reasoning on much more dynamic data than is currently possible. © 2013 Springer-Verlag

Веб-ресурс для перегляду 3D моделей з використанням технології WebGL

У першому розділі досліджується актуальність проблеми, проводиться аналіз існуючих аналогів. Другий розділ присвячений формування мети дипломної роботи та задач проекту, вибору засобів реалізації та плануванню робіт. У третьому розділі виконується проектування веб-ресурсу, де наведені діаграми у нотації IDF0 та Use Case.Останній розділ присвячений детальному опису практичної реалізації проекту: виконання прототипування веб-сторінки, розмітка та форматування веб-ресурсу, налаштування та перевірка працездатності веб-браузера з WebGL, опис реакції на дії користувача, розробка функцій маніпуляцій над моделлю. Результатом проведеної роботи є розроблений веб-ресурс, який дозволяє користувачу обирати одну із чотирьох моделей для візуалізації на веб-сторінці та виконувати базові маніпуляції з нею

The distributed ASCI supercomputer project

The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most interesting research results obtained so far in the DAS project

Less than meets the eye: the functional relevance of early visual cortex across the visual domain

In a series of areas in the human brains, among which the cerebral cortex, the visual perception is processed. The ‘early visual cortex’ is the area in the cerebral cortex where the visual information first enters. This dissertation reports a study in which the normal brain activity in the early visual cortex is temporarily and locally suppressed by means of Transcranial Magnetic Stimulation (TMS). This temporary suppression turns out to limit the recognition and awareness of visual information, the visual short-term memory and the influencing of behaviour on the basis of visual perception. This proves that the early virtual cortex does not play a specific role in visual perception, but that it is involved in several aspects of visual perception

Mixing Parallel and Sequential Computation for Top-down OWL RL Inference

The size and growth rate of the Semantic Web call for querying and reasoning methods that can be applied over very large amounts of data. In this paper, we discuss how we can enrich the results of queries by performing rule-based reasoning in a top-down fashion over large RDF knowledge bases. This paper focuses on the technical challenges involved in the topdown evaluation of the reasoning rules. First, we discuss the application of well-known algorithms in the QSQ family, and analyze their advantages and drawbacks. Then, we present a new algorithm, called RDF-SQ, which re-uses different features of the QSQ algorithms and introduces some novelties that target the execution of the OWL-RL rules. We implemented our algorithm inside the QueryPIE prototype and tested its performance against QSQ-R, which is the most popular QSQ algorithm, and a parallel variant of it, which is the current state-of-theart in terms of scalability.We used a large LUBM dataset with ten billion triples, and our tests show that RDF-SQ is significantly faster and more efficient than the competitors in almost all cases