Growing Self Organizing Map with an Imposed Binary Search Tree for Discovering Temporal Input Patterns

In this paper the Binary Search Tree Imposed Growing Self Organizing Map (BSTGSOM) is presented as an extended version of the Growing Self Organizing Map (GSOM), which has proven advantages in knowledge discovery applications. A Binary Search Tree imposed on the GSOM is mainly used to investigate the dynamic perspectives of the GSOM based on the inputs and these generated temporal patterns are stored to further analyze the behavior of the GSOM based on the input sequence. Also, the performance advantages are discussed and compared with that of the original GSOM

Growing Self Organising Map based Exploratory Analysis of Text Data

Textual data plays an important role in the modern world. The possibilities of applying data mining techniques to uncover hidden information present in large volumes of text collections is immense. The Growing Self Organizing Map (GSOM) is a highly successful member of the Self Organising Map family and has been used as a clustering and visualisation tool across wide range of disciplines to discover hidden patterns present in the data. A comprehensive analysis of the GSOM's capabilities as a text clustering and visualisation tool has so far not been published. These functionalities, namely map visualisation capabilities, automatic cluster identification and hierarchical clustering capabilities are presented in this paper and are further demonstrated with experiments on a benchmark text corpus

Growing Self Organising Map based Exploratory Analysis of Text Data

Textual data plays an important role in the modern world. The possibilities of applying data mining techniques to uncover hidden information present in large volumes of text collections is immense. The Growing Self Organizing Map (GSOM) is a highly successful member of the Self Organising Map family and has been used as a clustering and visualisation tool across wide range of disciplines to discover hidden patterns present in the data. A comprehensive analysis of the GSOM's capabilities as a text clustering and visualisation tool has so far not been published. These functionalities, namely map visualisation capabilities, automatic cluster identification and hierarchical clustering capabilities are presented in this paper and are further demonstrated with experiments on a benchmark text corpus

Molecular Dynamic Simulation of the Effect of Initial Surface Temperature on Arc Erosion Due to Ion Bombardment

This study focuses on the effects of initial surface temperature on arc erosion caused by ion bombardment. The simulation results show that higher surface temperature leads to a greater number of lost Cu atoms and an increased size of the erosion crater. This is due to the ability of the incident ions to have a greater sputtering yield at higher temperatures. Moreover, the Cu atoms tend to agglomerate and form clusters after ion bombardment while leaving the surface

Effect of Paper Type and Water Content in Paper on the Partitioning of 2-FAL between Liquid and Paper Insulations

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordFor nearly four decades 2-furfural (2-FAL) in transformer oil has been used as a chemical marker to indicate the ageing state of transformer paper insulation. Nevertheless, it has always been a challenge to define an acceptable limit for 2-FAL due to issues related to non-uniform temperature distribution in transformers, stability of 2-FAL in oil and its partitioning between liquid and solid insulation. Therefore, transformer users try to combine the laboratory findings, the operational experience and post-mortem analyses together for predicting ageing state of paper insulation through 2-FAL content in oil. Due to increase in the use of ester liquids in transformers, there is a need to investigate the ability to use 2-FAL as a paper ageing indicator for ester based insulation systems. Laboratory ageing studies have shown that 2-FAL is indeed generated in ester based insulation systems. However, there is a lack of understanding related to the partitioning of 2-FAL in ester based insulation systems. This paper studies the partitioning of 2-FAL in synthetic ester based insulation systems and compares to that in mineral oil based insulation systems with the focus on the effect of paper type and water content in paper. Under the investigated conditions the synthetic ester had higher partitioning coefficients (ratio between the 2-FAL content in oil and paper) than the mineral oil. Partitioning coefficients in both oil types decreased with the increase of the water content in paper. However, change in paper type did not significantly affect the partitioning coefficients in this study

Electrical Erosion Resistance of Graphene Reinforced Cu-W Circuit Breaker Contact Materials under 5 kA Arc

This work integrates experimental and MD simulation approaches to study the role of graphene in G-Cu-W composites. Arcing tests were conducted on G-Cu-W and Cu-W contact samples under a 5kA peak current. Experimental results show that adding graphene leads to a lower surface roughness of the sample following arcing. MD simulation results indicate that the G-Cu-W model exhibits a smoother surface and fewer lost metal atoms than the Cu-W model due to the protective effect of graphene layer

Effect of Waiting Time on Concentration of Chemical Markers measured on Laboratory Ageing Samples

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordLaboratory scale thermal ageing experiments have been used not only to study the degradation of the insulation materials but also to understand the variation of chemical markers in liquid during the ageing process. However, trends obtained from different experiments often disagree with each other due to experimental variations such as material type, material ratio and ageing temperature. In addition to these well-known factors, there are lesser-known factors such as the duration for which samples are left at room temperature after an ageing experiment, which could affect the concentration of chemical markers in liquid. It is known that temperature could affect the partitioning of chemical markers among the liquid, solid and gas phase. Hence the concentration of certain chemical-markers in liquid could vary depending on the duration for which samples are left at room temperature prior to the sampling of oil for the measurements. This paper investigates the effect of this sampling period on the variation of chemical markers including water, methanol and ethanol in liquid after a laboratory scale ageing experiment conducted at 150 °C. Results showed that the concentration of the investigated chemical markers in liquid decrease continuously when the sample is left at room temperature, with water having the highest reduction followed by methanol and ethanol

Frequency Domain Measurements for Diagnosis of Power Transformers: Experiences from Australia, Malaysia, Sri Lanka and UK

This is the author accepted manuscript. The final version is available from CIGRE via the link in this recordPower transformers and their performance and reliability in electric power networks are important research issues of power systems. Much information has already been collected and reported; however, it is rare to report comparisons of transformer service performance under different geographical locations and working conditions. CIGRE Working Group A2.37 collected information on 964 transformer failures from 58 utilities and 21 countries covering the period from 1996 to 2009. The main failure modes included failures in windings, tap changers, bushings, insulation, and core. As estimated, based on available literature, nearly 50% of the failures could be related to transformer windings and insulation. This collective paper summarizes experiences from the use of diagnostic tools based on frequency domain measurements at different geographical regions of the world. It starts with a short introduction to response measurements in frequency domain for condition assessment of transformers; then theoretical backgrounds of the two widely used response measurements, namely Frequency Dielectric Spectroscopy (FDS) and Frequency Response Analysis (FRA), are presented. Afterward details of tested transformers and measurement procedures are described for which selected set of FDS and FRA measurement results are analysed for respectively elucidating their potential in assessment of moisture content, ageing degree and fault identi cation

Modelling vertical drains with vacuum preloading considering the soil structure characteristics

Vertical drains accelerate consolidation and as such they are a very effective and popular ground improvement method. When vacuum preloading is applied with vertical drains, consolidation increases even more and the stability of an embankment is enhanced due to the inward lateral movement exerted by vacuum preloading. Previous analytical models developed to predict consolidation when vacuum preloading is used with vertical drains assumed average compressibility and permeability values within the applied stress range. Even though the smear effects were incorporated into the solution by considering a reduced but constant permeability inside the smear zone, the actual variation of permeability was ignored in the vacuum preloading models developed. More importantly, compressibility of the in-situ clay structure due to the installation of a mandrel driven drain was often ignored as well. The aim of this study is to develop an analytical solution for vacuum preloading which accurately represents the variations in compressibility and permeability in actual ground conditions as a result of drain installations. The disturbed zone created by drain installation can be characterised by using the extent of the smear zone and the ratio of the horizontal coefficient of permeability in the undisturbed zone and in the smear zone. These parameters were obtained using laboratory experiments performed on large-scale tests of samples of remoulded clay. Laboratory tests performed on samples extracted around an actual drain installed in field conditions indicated that soil was subjected to more smear under field conditions than was previously anticipated. Furthermore, this study revealed that the compressibility of soil was also adversely affected by the changes to the soil structure, and therefore it was deemed imperative to capture these changes in the analytical models developed for radial consolidation with vacuum pressure. A novel mathematical model was developed to incorporate soil destructuring due to drain installation and the associated changes in compressibility as the soil is improved using vertical drains and vacuum preloading. A more realistic distribution of permeability was assumed within the smear zone and the variation in permeability with the void ratio was also considered in the analysis. The predictions of average excess pore water pressure, degree of consolidation and resultant settlement, and the consolidation responses obtained using this analytical model were compared with other existing models. The importance of this model is illustrated via the case study simulations of two embankments in Australia and China that were stabilised with vertical drains; the proposed model gave more accurate predictions than the previous models. To model more realistic soil behaviour, variations in soil compressibility and permeability were incorporated into the latest edition of the PLAXIS finite element package which enabled the application of vacuum pressure, and very good agreement was observed between simulated results and the field data. Laboratory tests were conducted on reconstituted and in-situ soil samples obtained from a soft clay site at Ballina, using the newly designed consolidation apparatus that can enable radial consolidation with vacuum pressure. These experiment results enabled the empirical relationship between the vacuum surcharge ratio and lateral strain to be postulated, and they can also be used as a design tool in initial embankment planning

p53-Mediated Oxidative Stress Enhances Indirubin-3′-Monoxime-Induced Apoptosis in HCT116 Colon Cancer Cells by Upregulating Death Receptor 5 and TNF-Related Apoptosis-Inducing Ligand Expression

Indirubin-3′-monoxime (I3M) exhibits anti-proliferative activity in various cancer cells; however, its anti-cancer mechanism remains incompletely elucidated. This study revealed that I3M promotes the expression of death receptor 5 (DR5) and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) in HCT116 p53+/+ cells, resulting in caspase-mediated apoptosis. However, this study demonstrated that HCT116 p53−/− cells were insensitive to I3M-mediated apoptosis, indicating that I3M-induced apoptosis depends on the p53 status of HCT116 cells. Additionally, in HCT116 p53-/- cells, I3M significantly increased Ras expression, while in HCT116 p53+/+ cells, it reduced Ras expression. Furthermore, I3M remarkably increased the production of reactive oxygen species (ROS), which were reduced in transient p53 knockdown, indicating that I3M-mediated apoptosis was promoted by p53-mediated ROS production. Our results also showed that I3M enhanced transcription factor C/EBP homologous protein (CHOP) expression, resulted in endoplasmic reticulum (ER) stress-mediated DR5 expression, which was upregulated by ROS production in HCT116 p53+/+ cells. Moreover, co-treatment with I3M and TRAIL enhanced DR5 expression, thereby triggering TRAIL-induced apoptosis of HCT116 p53+/+ cells, which was interfered by a DR5-specific blocking chimeric antibody. In summary, I3M potently enhances TRAIL-induced apoptosis by upregulating DR5 expression via p53-mediated ROS production in HCT116 p53+/+ cells. However, HCT116 p53−/− cells were less sensitive to I3M-mediated apoptosis, suggesting that I3M could be a promising anti-cancer candidate against TRAIL-resistant p53+/+ cancer cells. Additionally, this study also revealed that I3M sensitizes colorectal cancer cells such as HT29 and SW480 to TRAIL-mediated apoptosis