Papers by tuan anh Nguyen
Sensors and Actuators B: Chemical, 2011
Anti-Corrosion Methods and Materials, 2011
Purpose -This work seeks to present a systematic study that aimed to provide quantitative underst... more Purpose -This work seeks to present a systematic study that aimed to provide quantitative understanding of the fundamental factors that influence the chloride threshold of pitting corrosion of steel in concrete, by conducting a set of laboratory tests to assess the corrosion potential (E corr ) and pitting potential (E pit ) of steel coupons in simulated concrete pore solutions. Design/methodology/approach -With the aid of artificial neural network, the laboratory data were used to establish a phenomenological model correlating the influential factors (total chloride concentration, chloride binding, solution pH, and dissolved oxygen (DO) concentration) with the pitting risk (characterized by E corr 2 E pit ). Three-dimensional response surfaces were then constructed to illustrate such predicted correlations and to shed light on the complex interactions between various influential factors. Findings -The results indicate that the threshold [Cl 2 ]/[OH 2 ] of steel rebar in simulated concrete pore solutions is a function of DO concentration, pH and chloride binding, instead of a unique value. Research limitations/implications -The limitations and implications of the research findings were also discussed. Practical implications -This research could have significant practical implications in predicting the service life of new or existing reinforced concrete in chloride-laden environments. Originality/value -This study further advances the knowledge base relevant to the chloride-induced corrosion of steel rebar in concrete.
Lecture Notes in Computer Science, 2003
Solving time constraint problems in wide area distributed computing environment is a challenge. W... more Solving time constraint problems in wide area distributed computing environment is a challenge. We address this challenge by providing programmers a method to express their problems based on a parallelization scheme. The scheme consists of a decomposition ...
Proceedings International Parallel and Distributed Processing Symposium, 2003
Efficient data access is important to achieve high performance in data intensive computing. This ... more Efficient data access is important to achieve high performance in data intensive computing. This paper presents a method of passive data access in the framework of ParoC++-a parallel object-oriented programming environment. ParoC++ extends C++ to distributed environments with the integration of user requirements into parallel objects. Passive data access enables the data source to initiate and store data directly to a user-specified address space. This ability allows better overlapping between computation and communication by data prediction, partial data processing and auto-data aggregation from multiple sources. Some experiments have been done, showing the scalability and the efficiency of passive data access in ParoC++ compared to direct data access methods.
Future Generation Computer Systems, 2007
Despite the fact that Grid computing is the main theme of distributed computing research during t... more Despite the fact that Grid computing is the main theme of distributed computing research during the last few years, programming on the Grid is still a huge difficulty to normal users. The POP-C++ programming system has been built to provide Grid programming facilities which greatly ease the development and the deployment of parallel applications on the Grid. The original parallel object model used in POP-C++ is a combination of powerful features of object-oriented programming and of high-level distributed programming capabilities. The model is based on the simple idea that objects are suitable structures to encapsulate and to distribute heterogeneous data and computing elements over the Grid. Programmers can guide the resource allocation for each object through the high-level resource descriptions. The object creation process, supported by the POP-C++ runtime system, is transparent to programmers. Both inter-object and intra-object parallelism are supported through various method invocation semantics. The POP-C++ programming language extends C++ to support the parallel object model with just a few new keywords. In this paper, we present the Grid programming aspects of POP-C++. With POP-C++, writing a Grid-enabled application becomes as simple as writing a sequential C++ application.
Proceedings of the 2014 conference ICT for Sustainability, 2014
Lecture Notes in Computer Science, 2003
Adaptive utilization of resources in a highly heterogeneous computational environment such as the... more Adaptive utilization of resources in a highly heterogeneous computational environment such as the Grid is a difficult question. In this paper, we address an object-oriented approach to the solution using requirement-driven parallel objects. Each parallel object is a self-described, shareable and passive object that resides in a separate memory address space. The allocation of the parallel object is driven by the constraints on the resource on which the object will live. A new parallel programming paradigm is presented in the context of ParoC++ -a new parallel objectoriented programming environment for high performance distributed computing. ParoC++ extends C++ for supporting requirement-driven parallel objects and a runtime system that provides services to run ParoC++ programs in distributed environments. An industrial application on realtime image processing is used as a test case to the system. The experimental results show that the ParoC++ model is efficient and scalable and that it makes easier to adapt parallel applications to dynamic environments.
Lecture Notes in Computer Science, 2007
A Virtual Organisation (VO) is a temporary alliance of autonomous, diverse, and geographically di... more A Virtual Organisation (VO) is a temporary alliance of autonomous, diverse, and geographically dispersed organisations, where the participants pool resources, information and knowledge in order to meet common objectives. This requires dynamic security policy management. We propose an authorisation policy management model called recognition of authority (ROA) which allows dynamically trusted authorities to adjust the authorisation policies for VO resources. The model supports dynamic delegation of authority, and the expansion and contraction of organizations in a VO, so that the underlying authorisation system is able to use existing user credentials issued by participating organisations to evaluate the user's access rights to VO resources.
2013 35th International Conference on Software Engineering (ICSE), 2013
Pharmaceutical Prices in the 21st Century, 2014
Infection Genetics and Evolution, 2010
Rotavirus is the main cause of acute viral gastroenteritis in infants and young children worldwid... more Rotavirus is the main cause of acute viral gastroenteritis in infants and young children worldwide. Surveillance of group A rotavirus has been conducted in Chiang Mai, Thailand since 1987 up to 2004 and those studies revealed that group A rotavirus was responsible for about 20-61% of diarrheal diseases in hospitalized cases. In this study, we reported the continuing surveillance of group A rotavirus in 2005 and found that group A rotavirus was detected in 43 out of 147 (29.3%) stool samples. Five different G and P genotype combinations were detected, G1P[8] (27 strains), G2P[4] (12 strains), G9P[8] (2 strains), G3P[8] (1 strain), and G3P[10] (1 strain). In addition, analysis of their genotypic linkages of G (VP7), P (VP4), I (VP6), E (NSP4), and H (NSP5) genotypes demonstrated that the rotaviruses circulating in Chiang Mai, Thailand carried 3 unique linkage patterns. The G1P[8], G3P[8], and G9P[8] strains carried their VP6, NSP4, NSP5 genotypes of I1, E1, H1, respectively. The G2P[4] strains were linked with I2, E2, H2 genotypes, while an uncommon G3P[10] genotype carried unique genotypes of I8, E3 and H6. These findings provide the overall picture of genotypic linkage data of rotavirus strains circulating in Chiang Mai, Thailand.
The present research evaluated the corrosion and inhibition performances of steel-mortar samples ... more The present research evaluated the corrosion and inhibition performances of steel-mortar samples with various levels of NaCl and corrosion inhibitors admixed in fresh mortar (0.05M DGP, 0.5M SN, and 0.05M DMEA). FESEM, EDX and XPS were used to analyze the fracture surfaces of the steel-mortar interfacial region for samples exposed to various time periods of ponding by 3% NaCl solution. The admixing of NaCl and the corrosion inhibitors in fresh mortar altered the morphology and microstructure of the hardened mortar at the steel-mortar interfacial region. The admixing of the corrosion inhibitors in fresh mortar increased the risk of carbonation of cement hydrates at the steel-mortar interfacial region, but partially displaced chloride ions. Chloride (either admixed or ingressed) and the admixed corrosion inhibitors facilitated the formation of different cement hydrates and affected chloride binding.at the steel-mortar interfacial region, all of which may affect the steel corrosion and its inhibition.
Journal of Computing Sciences in Colleges, 2000
Teaching Network Security course is a challenging task. One of the challenges is that networks ha... more Teaching Network Security course is a challenging task. One of the challenges is that networks have become more complicated and prone to attacks. In response to the challenge, the set of networking and security protocols and mechanisms continue to evolve, increasing the number of security technologies a network engineer needs to master in order to secure a network. This paper describes our experience of applying a network security development model to developing a network security lab. Developing network security is an iterative process, encompassing the analysis of vulnerabilities and threats, construction of policies, design of network architecture, integration plan of control measures, implementation of the design, and the operation and maintenance of a secure network. While Network Security has become an increasingly complicated topic to teach, we have learned from experiences the significance of a well-defined network security development process for teaching the development of secure networks.
Journal of Computing Sciences in Colleges, 2000
* Copyright © 2006 by the Consortium for Computing Sciences in Colleges. Permission to copy witho... more * Copyright © 2006 by the Consortium for Computing Sciences in Colleges. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the CCSC copyright notice and the title of the ...
Science China-technological Sciences, 2009
The present research brings new insights on the role of admixed corrosion inhibitors in the proce... more The present research brings new insights on the role of admixed corrosion inhibitors in the processes of cement hydration and rebar corrosion. The admixing of NaCl and the corrosion inhibitors in fresh mortar was found to alter the morphology and microstructure of the hardened mortar at the steel-mortar interfacial region. The admixing of the inhibitors increased the risk of carbonation of cement hydrates at the steel-mortar interfacial region, but partially displaced chloride ions. Chloride and the admixed inhibitors facilitated the formation of different cement hydrates and affected chloride binding at the steel-mortar interfacial region. The admixing of all three inhibitors was found to increase the polarization resistance of steel, indicating reduced corrosion rate of the steel over 48-day exposures to salt ponding
Accounting and Finance, 2004
The present study examines the impact of the announcement of special dividends for a sample of Au... more The present study examines the impact of the announcement of special dividends for a sample of Australian companies over the period July 1989 to June 2002. The risk-adjusted price reaction to special dividend announcements from the day before the announcement to the day after the announcement (day −1 to day 1) is positive and statistically significant, averaging 3.67 per cent. Initial special dividend announcements (4.68 per cent) led to stronger price reaction than special dividend announcements that follow an earlier special dividend (1.51 per cent) in the previous year. The magnitude of price reactions to special dividend announcements is statistically related to the size of the special dividend, the existence of prior special dividend announcements, abnormal cash flow for the year ended after the special dividend announcement, the existence of dividend reinvestment plans (DRP) versus non-DRP, and a preannouncement effect. Finally, we found strong support for the information content/signalling hypothesis for special dividend announcements that do not participate in DRP and limited support for those associated with DRP.
Surface & Coatings Technology, 2009
Homogeneous epoxy coatings containing nanoparticles of SiO2, Zn, Fe2O3 and halloysite clay were s... more Homogeneous epoxy coatings containing nanoparticles of SiO2, Zn, Fe2O3 and halloysite clay were successfully synthesized on steel substrates by room-temperature curing of a fully mixed epoxy slurry diluted by acetone. The surface morphology and mechanical properties of these coatings were characterized by scanning electron microscopy and atomic force microscopy, respectively. The effect of incorporating various nanoparticles on the corrosion resistance of epoxy-coated steel was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The electrochemical monitoring of the coated steel over 28 days of immersion in both 0.3 wt.% and 3 wt.% NaCl solutions suggested the beneficial role of nanoparticles in significantly improving the corrosion resistance of the coated steel, with the Fe2O3 and halloysite clay nanoparticles being the best. The SiO2 nanoparticles were found to significantly improve the microstructure of the coating matrix and thus enhanced both the anticorrosive performance and Young's modulus of the epoxy coating. In addition to enhancing the coating barrier performance, at least another mechanism was at work to account for the role of the nanoparticles in improving the anticorrosive performance of these epoxy coatings.
Authorization infrastructures manage privileges and render access control decisions, allowing app... more Authorization infrastructures manage privileges and render access control decisions, allowing applications to adjust their behavior according to the privileges allocated to users. This paper describes the PERMIS role based authorization infrastructure along with its conceptual authorisation, access control, and trust models. PERMIS has the novel concept of a credential validation service, which verifies a user's credentials prior to access control decision making and enables the distributed management of credentials. Details of the design and the implementation of PERMIS are presented along with details of its integration with Globus Toolkit, Shibboleth and GridShib. A comparison of PERMIS with other authorization and access control implementations is given, along with our plans for the future. Figure 1: High Level Conceptual Model of an Authorisation Infrastructure
Journal of Medical Virology, 2005
A total of 276 fecal specimens collected from infants and children admitted to hospital with acut... more A total of 276 fecal specimens collected from infants and children admitted to hospital with acute gastroenteritis in Ho Chi Minh City, Vietnam from October 2002 to September 2003, were tested for the presence of enteroviruses by RT-PCR and virus isolation. Enteroviruses were detected in 27 patients by RT-PCR corresponding to 9.8%. However, only four enterovirus strains could be isolated by cell culture with two different cell lines CaCo2 and Vero, showing specific cytopathic effect (CPE). The results clearly indicate that RT-PCR is a sensitive, specific assay to investigate the true burden of acute gastroenteritis due to enteroviruses in clinical fecal specimens. In the present study, enteroviruses were identified throughout the year except in May and the highest number was in December. Enteroviruses were subjected to molecular analysis by sequencing. It was found that enterovirus strains detected were classified further into two distinct genetic clusters (I, II) and demonstrated the great genetic diversity among them. Based on genetic analysis, 5′ noncoding region (5′ NCR) sequences suggested the predominant presence of Vietnamese enteroviruses with the greatest similarities to coxsakieviruses (51.9%) and echoviruses (29.6%). Interestingly, two of the sequenced specimens of enteroviruses were similar to a new strain called enterovirus 74. This report is the first detection of enteroviral infection in feces from infants and children admitted to hospital with acute gastroenteritis in Vietnam. J. Med. Virol. 77:257–264, 2005. © 2005 Wiley-Liss, Inc.
Uploads
Papers by tuan anh Nguyen