281 research outputs found
PROGRAMMING LANGUAGES À LA CARTE
Code reuse in computer language development is an open research problem. Feature-oriented programming is a vision of computer programming in which features can be implemented separately, and then combined to build a variety of software products; the idea of combining feature orientation and language development is relatively recent. Many frameworks for modular language development have been proposed during the years, but, although there is a strong connection between modularity and feature-orientation development, only few of these frameworks provide primitives to combine these two concepts. This work presents a model of modular language development that is directed towards feature orientation. We describe its implementation in the Neverlang framework. The model has been evaluated through several experiences: among the others, we present a code generator for a state machine language, that we use as a means to compare to other state-of-the-art frameworks, and a JavaScript interpreter implementation that further illustrates the capabilities of our solution
Control of cracking in concrete by steel reinforcement : an examination of some of the mechanisms involved
The techniques tried up till now to model the problem of cracking in reinforced concrete have been largely empirical. Many relationships have been identified between certain parameters and the occurrence and size of cracks. This thesis reviews these, reports on the current state of knowledge, and discusses some of the theories proposed. Because of the great variation and complexity of the materials and stress interactions involved, the problem has to date defied completely objective theoretical modelling. The finite element method provides a powerful new modelling tool for theoretical simulation of complex real problems. Recent developments on constitutive models for concrete make this method extremely attractive for use in this case. This thesis attempts to make use of these tools by carrying out some analyses of the cracking of reinforced concrete prisms stressed in tension. The method is found to be a viable way of examining mechanisms and effects which are not ordinarily visible in laboratory experiments. These mechanisms are discussed in the light of the experimental findings recorded in the literature
Choosy and Picky: Configuration of Language Product Lines
Although most programming languages naturally share several language features, they are typically implemented as a monolithic product. Language features cannot be plugged and unplugged from a language and reused in another language. Some modular approaches to language construction do exist but composing language features requires a deep understanding of its implementation hampering their use. The choose and pick approach from software product lines provides an easy way to compose a language out of a set of language features. However, current approaches to language product lines are not sufficient enough to cope with the complexity and evolution of real world programming languages. In this work, we propose a general light-weight bottom-up approach to automatically extract a feature model from a set of tagged language components. We applied this approach to the Neverlang language development framework and developed the AiDE tool to guide language developers towards a valid language composition. The approach has been evaluated on a decomposed version of Javascript to highlight the benefits of such a language product line
Research Reports: 1984 NASA/ASEE Summer Faculty Fellowship Program
A NASA/ASEE Summer Faulty Fellowship Program was conducted at the Marshall Space Flight Center (MSFC). The basic objectives of the programs are: (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA Centers. The Faculty Fellows spent ten weeks at MSFC engaged in a research project compatible with their interests and background and worked in collaboration with a NASA/MSFC colleague. This document is a compilation of Fellows' reports on their research during the summer of 1984. Topics covered include: (1) data base management; (2) computational fluid dynamics; (3) space debris; (4) X-ray gratings; (5) atomic oxygen exposure; (6) protective coatings for SSME; (7) cryogenics; (8) thermal analysis measurements; (9) solar wind modelling; and (10) binary systems
Research reports: 1985 NASA/ASEE Summer Faculty Fellowship Program
A compilation of 40 technical reports on research conducted by participants in the 1985 NASA/ASEE Summer Faculty Fellowship Program at Marshall Space Flight Center (MSFC) is given. Weibull density functions, reliability analysis, directional solidification, space stations, jet stream, fracture mechanics, composite materials, orbital maneuvering vehicles, stellar winds and gamma ray bursts are among the topics discussed
Angiogenic imbalance in preeclampsia: Pathogenic, diagnostic and prognostic implications
Preeclampsia is a major cause of maternal and fetal/neonatal morbidity and mortality worldwide.
The disorder has been dubbed the “disease of theories” because of the multiple plausible hypotheses proposed to explain its occurrence. This thesis focuses on an altered angiogenic imbalance in pregnancy reflected by elevated placenta-derived sFlt-1 and decreased PlGF levels weeks before the onset of the phenotypes of preeclampsia. The incremental value of the biomarkers on top of the current standard of diagnosis are investigated, and a well-discriminating prediction model is developed to predict the risk of maternal and fetal/neonatal complications in individual pregnant women
Understanding pathways
The challenge with todays microarray experiments is to infer biological conclusions
from them. There are two crucial difficulties to be surmounted in this challenge:(1)
A lack of suitable biological repository that can be easily integrated into computational
algorithms. (2) Contemporary algorithms used to analyze microarray data are unable to
draw consistent biological results from diverse datasets of the same disease.
To deal with the first difficulty, we believe a core database that unifies available
biological repositories is important. Towards this end, we create a unified biological
database from three popular biological repositories (KEGG, Ingenuity and Wikipathways).
This database provides computer scientists the flexibility of easily integrating
biological information using simple API calls or SQL queries.
To deal with the second difficulty of deriving consistent biological results from the
experiments, we first conceptualize the notion of “subnetworks”, which refers to a
connected portion in a biological pathway. Then we propose a method that identifies
subnetworks that are consistently expressed by patients of he same disease phenotype.
We test our technique on independent datasets of several diseases, including ALL,
DMD and lung cancer. For each of these diseases, we obtain two independent microarray
datasets produced by distinct labs on distinct platforms. In each case, our technique
consistently produces overlapping lists of significant nontrivial subnetworks from two
independent sets of microarray data. The gene-level agreement of these significant
subnetworks is between 66.67% to 91.87%. In contrast, when the same pairs of
microarray datasets were analysed using GSEA and t-test, this percentage fell between
37% to 55.75% (GSEA) and between 2.55% to 19.23% (t-test). Furthermore, the genes
selected using GSEA and t-test do not form subnetworks of substantial size. Thus
it is more probable that the subnetworks selected by our technique can provide the
researcher with more descriptive information on the portions of the pathway which
actually associates with the disease.
Keywords: pathway analysis, microarra
Movement of solutes in structured soils during intermittent leaching : a theoretical and laboratory study
PhD ThesisSoil salinity is one of the major problems in and and semi-arid zones, affecting
up to 50% of arable land in Syria. Salt-affected soils are usually desalinized by
leaching the excess salts out of the soil profile. Some studies have shown that
applying the leaching water intermittently instead of continuously may result in
more efficient leaching. This thesis aims to investigate, theoretically and
experimentally, the benefits and limitations of intermittent leaching and to
develop mathematical models able to simulate solute transport through
structured soils under such conditions.
Laboratory leaching experiments were conducted on bi-continuum
media, as an analogue of structured soils, created by packing porous aggregates
(ceramic spheres or soil aggregates of uni- or multi- diameters) in glass
columns. The columns were either leached continuously or intermittently and
with different pore-water velocities. Intermittent leaching was undertaken
either under saturated or drained conditions. Under "saturated conditions" the
column remained saturated throughout the experiment, while under "drained
conditions" the column was allowed to drain at the beginning of each rest
period and remained like this until being saturated again for the next leaching
period. The solute concentration in the leachate was monitored continuously
(either using a flow-through conductivity cell, or by using ion-selective
electrodes for Ký and Br' ) to produce breakthrough curves. These curves were
used to investigate solute transport through such media and validate the
developed models.
The experiments showed that water savings of up to 22% under intermittent
leaching from a soil aggregate column were possible under saturated conditions.
Such saving increased with aggregate size, flow velocity and duration of rest
period. Under drained conditions, for ceramic spheres, 12% more solute was
leached with the same amount of water under intermittent leaching.
Two models were developed, the SIL (Saturated Intermittent Leaching)
and the DIL (Drained Intermittent Leaching) models, for saturated and drained
conditions respectively. The SIL model simulated solute transport in structured
soils under intermittent leaching. The governing equations during displacement
period were the mobile-immobile convection-dispersione quations. During the
rest period the flow is stopped, and the solute transfers only by diff-usion
between immobile and mobile water regions. The DIL model simulated solute
transport when the soil drained. Here, during the displacement period, the
mobile water was drained. The model simulated this using the equations of the
SIL model by assuming that air displaced the solution in a piston-type
displacement. During the rest periods the solute difluses within the aggregates
establishing a more uniform concentration in the immobile water across the
aggregate.
The models can be used with a wide range of column conditions and for
both sorbed and non-sorbed solutes. Both models were verified against
experimentarel sults.Al-Baath University, Syri
The Mechanical Properties of Carbon Fibre With Glass Fibre Hybrid Reinforced Plastics
Merged with duplicate record 10026.1/2475 on 15.03.2017 by CS (TIS)Fibre composite hybrid materials are generally plastics reinforced with two different
fibre species. The combination of these three materials (in this thesis they are carbon
fibres, glass fibres and polyester resin) allows a balance to be achieved between the properties
of the two monofibre composites. Over the fifteen years since the introduction of
continuous carbon fibre as a reinforcement, there has been considerable speculation
about the "hybrid effect", a synergistic strengthening of reinforced plastics with two
fibres when compared with the strength predicted from a weighted average from the component
composites.
A new equation is presented which predicts the extent of the hybrid effect. Experiments
with a variety of carbon-glass hybrids were undertaken to examine the validity of
the theory and the effect of the degree of inter-mixing of the fibres. The classification
and quantification of the hybrid microstructures was examined with a view to crosscorrelation
of the intimacy of mixing and the strength.
Mechanical tests were monitored with acoustic emission counting and acoustic emission
amplitude distribution equipment. Some specimens were subjected to one thermal cycle
to liquid nitrogen temperature prior to testing. Fracture surfaces were examined in the
scanning electron microscope.
Numerical analysis by finite element methods was attempted. A constant strain triangular
element was used initially, but in the later analyses the PAFEC anisotropic
isoparametric quadrilateral elements were used. The system was adapted so that a \Ir
singularity could be modelled, and post processor software was written to allow nodal
averaging of the stresses and the presentation of this data graphically as stress contour
maps
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