Doctor of Philosophy

dissertationMedical knowledge learned in medical school can become quickly outdated given the tremendous growth of the biomedical literature. It is the responsibility of medical practitioners to continuously update their knowledge with recent, best available clinical evidence to make informed decisions about patient care. However, clinicians often have little time to spend on reading the primary literature even within their narrow specialty. As a result, they often rely on systematic evidence reviews developed by medical experts to fulfill their information needs. At the present, systematic reviews of clinical research are manually created and updated, which is expensive, slow, and unable to keep up with the rapidly growing pace of medical literature. This dissertation research aims to enhance the traditional systematic review development process using computer-aided solutions. The first study investigates query expansion and scientific quality ranking approaches to enhance literature search on clinical guideline topics. The study showed that unsupervised methods can improve retrieval performance of a popular biomedical search engine (PubMed). The proposed methods improve the comprehensiveness of literature search and increase the ratio of finding relevant studies with reduced screening effort. The second and third studies aim to enhance the traditional manual data extraction process. The second study developed a framework to extract and classify texts from PDF reports. This study demonstrated that a rule-based multipass sieve approach is more effective than a machine-learning approach in categorizing document-level structures and iv that classifying and filtering publication metadata and semistructured texts enhances the performance of an information extraction system. The proposed method could serve as a document processing step in any text mining research on PDF documents. The third study proposed a solution for the computer-aided data extraction by recommending relevant sentences and key phrases extracted from publication reports. This study demonstrated that using a machine-learning classifier to prioritize sentences for specific data elements performs equally or better than an abstract screening approach, and might save time and reduce errors in the full-text screening process. In summary, this dissertation showed that there are promising opportunities for technology enhancement to assist in the development of systematic reviews. In this modern age when computing resources are getting cheaper and more powerful, the failure to apply computer technologies to assist and optimize the manual processes is a lost opportunity to improve the timeliness of systematic reviews. This research provides methodologies and tests hypotheses, which can serve as the basis for further large-scale software engineering projects aimed at fully realizing the prospect of computer-aided systematic reviews

Covert movement in English probing wh-questions

Besides fronted information-seeking questions, English also allows for two types of wh-in-situ ones: echo questions, which are used to request a repetition or a clarification of a previous utterance, and probing questions, which are often used in quiz shows, classroom settings, and child-directed speech to "prompt" the addressee for an answer. An acceptability judgment task shows that PQs with multiple wh-phrases get a significantly lower acceptability score than echo questions with multiple wh-phrases despite their similarity in surface structure, which suggests a syntactic difference below the surface. Independent syntactic evidence confirms the result and further suggests that while echo questions involve no syntactic movement (Dayal, 1996), probing questions involve covert wh-movement

IMPROVING AIR QUALITY IN HANOI, VIETNAM : STUDY OF FINE AND COARSE PARTICLES

Joint Research on Environmental Science and Technology for the Eart

Experimental study of short concrete columns reinforced with GFRP bars under monotonic loading

The glass fiber reinforced polymer (GFRP) bars are considered as an alternative reinforcement to steel in concrete structures subjected to chloride environment because of their non- corrosive and non-magnetic properties. To examine the applicability of GFRP bars to performance of concrete columns, this work was conducted. The effect of the compressive reinforcement ratio and stirrup spacing on the load carrying capacity of concrete columns reinforced with GFRP bars is experimentally investigated. Nine short concrete columns with dimensions of 150 × 150 × 600 mm were cast and tested until failure under displacement-controlled concentric loading. The experimental results demonstrated that by increasing the reinforcement ratio from 0.37% to 3.24%, the load-bearing capacity of GFRP RC columns was found to increase by an average of 28%. Moreover, the tested results confirmed that the GFRP stirrup spacing had a significant influence on the load-carrying capacity of the columns

Experimental study of short concrete columns reinforced with GFRP bars under monotonic loading

The glass fiber reinforced polymer (GFRP) bars are considered as an alternative reinforcement to steel in concrete structures subjected to chloride environment because of their non- corrosive and non-magnetic properties. To examine the applicability of GFRP bars to performance of concrete columns, this work was conducted. The effect of the compressive reinforcement ratio and stirrup spacing on the load carrying capacity of concrete columns reinforced with GFRP bars is experimentally investigated. Nine short concrete columns with dimensions of 150 × 150 × 600 mm were cast and tested until failure under displacement-controlled concentric loading. The experimental results demonstrated that by increasing the reinforcement ratio from 0.37% to 3.24%, the load-bearing capacity of GFRP RC columns was found to increase by an average of 28%. Moreover, the tested results confirmed that the GFRP stirrup spacing had a significant influence on the load-carrying capacity of the columns

A generalised finite difference scheme based on compact integrated radial basis function for flow in heterogeneous soils

In the present paper, we develop a generalised finite difference approach based on compact integrated radial basis function (CIRBF) stencils for solving highly nonlinear Richards equation governing fluid movement in heterogeneous soils. The proposed CIRBF scheme enjoys a high level of accuracy and a fast convergence rate with grid refinement owing to the combination of the integrated RBF approximation and compact approximation where the spatial derivatives are discretised in terms of the information of neighbouring nodes in a stencil. The CIRBF method is first verified through the solution of ordinary differential equations, 2-D Poisson equations and a Taylor-Green vortex. Numerical comparisons show that the CIRBF method outperforms some other methods in the literature. The CIRBF method in conjunction with a rational function transformation method and an adaptive time-stepping scheme is then applied to simulate 1-D and 2-D soil infiltrations effectively. The proposed solutions are more accurate and converge faster than those of the finite different method employed with a second-order central difference scheme. Additionally, the present scheme also takes less time to achieve target accuracy in comparison with the 1D-IRBF and HOC schemes

Concrete beams using seawater and sea sand reinforced with steel and GFRP rebars exposed to marine environment: An experimental study

Using fresh water and river sand in concrete mix composition makes a lot of negative impacts on resources and the environment while the source of sea sand and sea water is abundant and less harmful to the environment. However, sea sand and seawater in concrete can cause severe corrosion of the reinforcement, reducing the durability and bearing capacity of the structure. This paper illustrates the results of a comparative study on the flexural behavior of six corroded seawater sea-sand concrete (SWSSC) beams. The corrosion process of two concrete beams reinforced with traditional steel bars and four concrete beams reinforced with a combination of glass fiber reinforced polymer (GFRP) and steel bars was coupled by the effect of seawater exposure and sustained load. It was found that after exposure to a marine environment during the period of 60 months the GFRP bar retains surface integrity, meanwhile, the steel bars were significantly corroded with a cross-sectional area loss of approximately 13.93%. The decrease in bending stiffness, yield load, and ultimate load of the RC beams was found due to the deterioration of SWSSC and corrosion of steel bars.

Concrete beams using seawater and sea sand reinforced with steel and GFRP rebars exposed to marine environment: An experimental study

Using fresh water and river sand in concrete mix composition makes a lot of negative impacts on resources and the environment while the source of sea sand and sea water is abundant and less harmful to the environment. However, sea sand and seawater in concrete can cause severe corrosion of the reinforcement, reducing the durability and bearing capacity of the structure. This paper illustrates the results of a comparative study on the flexural behavior of six corroded seawater sea-sand concrete (SWSSC) beams. The corrosion process of two concrete beams reinforced with traditional steel bars and four concrete beams reinforced with a combination of glass fiber reinforced polymer (GFRP) and steel bars was coupled by the effect of seawater exposure and sustained load. It was found that after exposure to a marine environment during the period of 60 months the GFRP bar retains surface integrity, meanwhile, the steel bars were significantly corroded with a cross-sectional area loss of approximately 13.93%. The decrease in bending stiffness, yield load, and ultimate load of the RC beams was found due to the deterioration of SWSSC and corrosion of steel bars.