Ultra-Reliable Low-Latency Vehicular Networks: Taming the Age of Information Tail

While the notion of age of information (AoI) has recently emerged as an important concept for analyzing ultra-reliable low-latency communications (URLLC), the majority of the existing works have focused on the average AoI measure. However, an average AoI based design falls short in properly characterizing the performance of URLLC systems as it cannot account for extreme events that occur with very low probabilities. In contrast, in this paper, the main objective is to go beyond the traditional notion of average AoI by characterizing and optimizing a URLLC system while capturing the AoI tail distribution. In particular, the problem of vehicles' power minimization while ensuring stringent latency and reliability constraints in terms of probabilistic AoI is studied. To this end, a novel and efficient mapping between both AoI and queue length distributions is proposed. Subsequently, extreme value theory (EVT) and Lyapunov optimization techniques are adopted to formulate and solve the problem. Simulation results shows a nearly two-fold improvement in terms of shortening the tail of the AoI distribution compared to a baseline whose design is based on the maximum queue length among vehicles, when the number of vehicular user equipment (VUE) pairs is 80. The results also show that this performance gain increases significantly as the number of VUE pairs increases.Comment: Accepted in IEEE GLOBECOM 2018 with 7 pages, 6 figure

Utilization of Industrial By-Products/Waste to Manufacture Geopolymer Cement/Concrete

There has been a significant movement in the past decades to develop alternative sustainable building material such as geopolymer cement/concrete to control CO2 emission. Industrial waste contains pozzolanic minerals that fulfil requirements to develop the sustainable material such as alumino-silicate based geopolymer. For example, industrial waste such as red mud, fly ash, GBFS/GGBS (granulated blast furnace slag/ground granulated blast furnace slag), rice husk ash (RHA), and bagasse ash consist of minerals that contribute to the manufacturing of geopolymer cement/concrete. A literature review was carried out to study the different industrial waste/by-products and their chemical composition, which is vital for producing geopolymer cement, and to discuss the mechanical properties of geopolymer cement/concrete manufactured using different industrial waste/by-products. The durability, financial benefits and sustainability aspects of geopolymer cement/concrete have been highlighted. As per the experimental results from the literature, the cited industrial waste has been successfully utilized for the synthesis of dry or wet geopolymers. The review revealed that that the use of fly ash, GBFS/GGBS and RHA in geopolymer concrete resulted high compressive strength (i.e., 50 MPa–70 MPa). For high strength (>70 MPa) achievement, most of the slag and ash-based geopolymer cement/concrete in synergy with nano processed waste have shown good mechanical properties and environmental resistant. The alkali-activated geopolymer slag, red mud and fly ash based geopolymer binders give a better durability performance compared with other industrial waste. Based on the sustainability indicators, most of the geopolymers developed using the industrial waste have a positive impact on the environment, society and economy.publishedVersio

Application of generative design for structural optimization at the conceptual design phase

Optimization of structural components leads to higher performing designs, by reducing unnecessary cost and increasing the efficient use of material. The structural optimization process is a rigorous iterative time-consuming process. Developments within algorithmic aided design (AAD) tools have made it easier for structural engineers to achieve automation of optimization routines. Generative design (GD) provides optimization routines which can aid in the pursuit of optimal solutions, given a set of criteria. The use of GD in combination with finite element analysis (FEA), to optimize structural design, has yet to see noticeable adoption within the structural engineering community. This paper discusses two illustrative cases to demonstrate how GD tools have been applied to optimize structures at the conceptual phase. The results have been validated using FEM-design software. A workflow has been proposed, based on the lessons learnt from the cases. This workflow inherits characteristics that, when followed, yielded consistent and reliable results.publishedVersio

Stock Price Reaction to the Stock Splits Announcement of Listed Companies in the Colombo Stock Exchange

A stock split is a corporate event that directly impacts the number of a company’s shares and indirectly on stock prices. This study tests the effect of the stock splits on the share price of companies listed in the Colombo Stock Exchange during the periods of pre and post stock split announcement in accordance with the Efficient Market Hypothesis. The main objective of this paper is to identify the overall impact of a stock split announcement on stock prices. This study analyses 88 annual stock splits during the ten (10) year period from 2009 to 2019 by taking the listed companies in the Colombo Stock Exchange into consideration. It uses the event study methodology to test the market efficiency of the Colombo Stock Exchange, and the market model is run with the aid of abnormal returns, which are calculated based on daily closing stock prices and the All-Share Price Index. For analysing the results, the graphical analysis and t statistics have been utilized. According to the event day average abnormal return, the majority of stock splits were more negative than positive with a significant t value at 5% by indicating that investors were taking the stock split announcement as bad news just after the split announcement was released. Each day with a significant Average Abnormal Return shows more positives than negatives. Graphical results have shown both Average Abnormal Return, and Cumulative Average Abnormal Return has remained continuously negative up to 18 and 25 days, respectively, by implicating that stock splits have made a deleterious impact on stock return. This study finally concludes that the information regarding the stock splits has not been absorbed efficiently by the market because the market reactions before and after the date of the split announcement were significant at 5%, although the Average Abnormal Return got a quick reaction to the announcement. Furthermore, results had not provided evidence for Semi-Strong Form efficiency of the Colombo Stock Exchange since the significant stock price adjustments before and after the event day was noticed. By this study, the policymakers and investors are convinced that all information has not been incorporated into stock prices in making their decisions. Keywords: Efficient market hypothesis; Event study methodology; Signalling theory; Sri Lanka; Stock split

Relationship Between the Likelihood of Reporting Adverse Events Among Nursing Officers and Their Perceptions on Identified Barriers and Enablers for Reporting

In order to improve patient safety in hospital setups, learning from previous errors is important. Therefore the institute should have adequate data on adverse events which have occurred in their settings. The way of gathering those data is Adverse Event Reporting. The objective of this study was to measure the relationship between the likelihood of reporting adverse events by Nursing Officers in Medical, Surgical, Paediatric, Gynaecology and Obstetrics wards in the Teaching Hospital, Kandy and their perception on selected barriers and enablers, as identified in literature, for adverse event reporting. This was a quantitative study, and the study instrument was a validated self-administered questionnaire with a six point likert scale. Nursing officers working in Medical, Surgical, Paediatric, Gynaecology and Obstetrics wards in the Teaching Hospital, Kandy were the study population. The whole population was taken to this study as it is below the calculated sample size. Correlations between the likelihood of reporting adverse events was measured with the participants’ perceptions on  their training on adverse event reporting, leadership, feedback received for reported adverse events, knowledge on adverse event reporting, presence of culture of blame and the existing process of adverse event reporting. The response rate for the questionnaire was 69% (n=277).There was statistically significant positive moderate correlation between the participants’ likelihood of incident reporting and their perception on the process of reporting an adverse event (r = 0.591). Their perceptions on leadership (r = 0.472), perceived knowledge on incident reporting (r = 0.462), perception on feedback received for reported incidents (r = 0.438), perceived training received for incident reporting (r = 0.378) and the perception of the presence of culture of blame (r = 0.164) showed weak positive correlations with their likelihood of reporting adverse events. Simplification of the process of adverse event reporting can be recommended to improve incident reporting in these selected wards in the Teaching Hospital, Kandy

STUDY ON FLOOD INUNDATION IN PEKALONGAN, CENTRAL JAVA

Tidal flood or ‘rob’ is a serious problem in many coastal areas in Indonesia, including Pekalongan in the northern coast of Java island. This study aimed to simulate the flood inundation area for different scenarios of sea level rise, also to investigate the possibility of land subsidence that may further aggravate the problem of flooding in Pekalongan. In this study, the MIKE-21 model was used to simulate and predict the flood inundation area. Tidal data were generated from the Tide Model Drive (TMD). The tidal flood simulations were carried out for three different scenarios of sea level rise: 1) current situation, 2) next 50 years, assuming no sea level rise, and 3) next 50 years, assuming 50 cm of sea level rise. Based on the results, the ranges of water level rise in Pekalongan for each scenario were 0.23-1.27 m, 0.36-1.38 m, and 0.65-1.53 m, respectively. Meanwhile, ground displacement maps were derived from the ALOS/PALSAR data using Differential Interferometric Synthetic Aperture Radar (D-InSAR) technique. Twelve level 1.0 images of ALOS/PALSAR data acquired in ascending mode during 2008 to 2009 were collected and processed in time-series analyses. In total, 11 pairs of interferogram were produced by taking the first image in 2008 as the master image. The results showed that the average of land subsidence rate in Pekalongan city was 3 cm/year, and the subsidence mainly occurred in the western part of the city

Improvements for the workflow interoperability between BIM and FEM tools

Transferring models, developed using Building Information Modelling (BIM), to Finite Element Method (FEM) tools is an important task in the integration of structural engineering into the open BIM workflow. Such integration saves the time spent by a structural engineer modelling a structure from scratch. There are various problems that can arise while transferring from BIM to FEM tools. A common problem in transferring the geometry and data from the BIM model into an FEM tool is the question of where to place nodes. Each column, beam or slab is defined as a volume in the BIM model and must be interpreted as lines and areas in the FEM analysis. This can be problematic, as transfer of forces must happen at a singular point in the FEM analysis, while the BIM model may be ambiguous regarding where these points are to be placed. This paper discusses the problems that occur when transferring a model from BIM to FEM tools and how to reduce some common mistakes by improving the existing workflow. Based on the needs of local Norwegian industries, the study mainly focuses on the transference of analytical models from Revit software to FEM tools such as Focus Konstruksjon, Robot Structural Analysis and SOFiSTiK. Then, improvements for the existing workflow are proposed for the aforementioned interoperability between BIM and FEM tools and verified using a case study.publishedVersio